1 files changed, 6 insertions, 0 deletions
diff --git a/spec/ruby/core/queue/enq_spec.rb b/spec/ruby/core/queue/enq_spec.rb
new file mode 100644
index 0000000000..c69c496fbc
--- /dev/null
+++ b/spec/ruby/core/queue/enq_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/queue/enque'
+
+describe "Queue#enq" do
+  it_behaves_like :queue_enq, :enq, -> { Queue.new }
+end
diff --git a/spec/ruby/.mspec.constants b/spec/ruby/.mspec.constants
index e88e58989f..4da3633715 100644
--- a/spec/ruby/.mspec.constants
+++ b/spec/ruby/.mspec.constants
@@ -39,8 +39,11 @@ CodingUS_ASCII
 CodingUTF_8
 ComparisonTest
 ConstantSpecsIncludedModule
+ConstantSpecsTwo
+ConstantSpecsThree
 ConstantVisibility
 Coverage
+CoverageSpecs
 CustomArgumentError
 DRb
 DRbIdConv
@@ -55,6 +58,7 @@ DefSpecsLambdaVisibility
 DefineMethodByProcClass
 DefineMethodSpecClass
 DefineSingletonMethodSpecClass
+Delegator
 DescArray
 DescObjectTest
 Digest
@@ -71,6 +75,7 @@ EvalBindingProcA
 Exception2MessageMapper
 ExceptionForMatrix
 Fcntl
+Fiddle
 FileStat
 FileUtils
 Find
@@ -141,6 +146,7 @@ Prime
 Private
 ProcFromMethod
 Psych
+RactorLocalSingleton
 REXML
 RUBY_SIGNALS
 RbReadline
@@ -148,8 +154,10 @@ Readline
 ReceiverClass
 RegexpSpecsSubclass
 RegexpSpecsSubclassTwo
+Reline
 RescueInClassExample
 Resolv
+Ripper
 SHA1Constants
 SHA256Constants
 SHA384Constants
@@ -161,6 +169,7 @@ SecondClass
 SecureRandom
 Set
 Shellwords
+SimpleDelegator
 SingleForwardable
 Singleton
 Socket
@@ -188,6 +197,7 @@ TimeoutError
 UDPSocket
 UNIXServer
 UNIXSocket
+URI
 UnaryMinusTest
 UnicodeNormalize
 UnloadableDumpableDir
@@ -195,6 +205,7 @@ UserArray
 UserCustomConstructorString
 UserDefined
 UserDefinedImmediate
+UserDefinedString
 UserDefinedWithIvar
 UserHash
 UserHashInitParams
diff --git a/spec/ruby/.rubocop.yml b/spec/ruby/.rubocop.yml
index cc31ff50b3..0b5dcb80a2 100644
--- a/spec/ruby/.rubocop.yml
+++ b/spec/ruby/.rubocop.yml
@@ -1,20 +1,29 @@
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 3.2
   DisplayCopNames: true
   Exclude:
     - command_line/fixtures/bad_syntax.rb
+    - core/exception/fixtures/syntax_error.rb
   DisabledByDefault: true
+  NewCops: disable
+
+Layout/IndentationConsistency:
+  Enabled: true
 
 Layout/TrailingWhitespace:
   Enabled: true
 
-Layout/TrailingBlankLines:
+Layout/TrailingEmptyLines:
   Enabled: true
   Exclude:
     - library/coverage/fixtures/some_class.rb
 
+Layout/SpaceInLambdaLiteral:
+  Enabled: true
+  EnforcedStyle: require_space
+
 Lint:
   Enabled: true
 
@@ -28,16 +37,27 @@ Lint/AssignmentInCondition:
 Lint/BooleanSymbol:
   Enabled: false
 
+Lint/DeprecatedOpenSSLConstant:
+  Exclude:
+    - library/openssl/digest/**/*.rb
+
 Lint/InterpolationCheck:
   Enabled: false
 
 Lint/LiteralAsCondition:
   Enabled: false
 
-Lint/UnneededRequireStatement:
+# Required to support Ruby 3.0
+Lint/RedundantRequireStatement:
+  Exclude:
+    - core/fiber/**/*.rb
+    - library/fiber/**/*.rb
+    - optional/capi/fiber_spec.rb
+
+Lint/RedundantSplatExpansion:
   Enabled: false
 
-Lint/UnneededSplatExpansion:
+Lint/RescueException:
   Enabled: false
 
 Lint/UnifiedInteger:
@@ -52,12 +72,58 @@ Lint/UnusedMethodArgument:
 Lint/UselessAssignment:
   Enabled: false
 
-Lint/UselessComparison:
+Lint/BinaryOperatorWithIdenticalOperands:
   Enabled: false
 
+Lint/EmptyConditionalBody:
+  Enabled: false # buggy
+
 Lint/Void:
   Enabled: false
 
+Lint/ConstantDefinitionInBlock:
+  Enabled: false
+
+Lint/RaiseException:
+  Enabled: false
+
+Lint/FloatComparison:
+  Enabled: false
+
+Lint/DeprecatedClassMethods:
+  Enabled: false
+
+Lint/UnreachableLoop:
+  Enabled: false
+
+Lint/MissingSuper:
+  Enabled: false
+
+Lint/UselessMethodDefinition:
+  Enabled: false
+
+Lint/UselessTimes:
+  Enabled: false
+
+Lint/MixedRegexpCaptureTypes:
+  Enabled: false
+
+Lint/DuplicateElsifCondition:
+  Enabled: false
+
+Lint/OutOfRangeRegexpRef:
+  Enabled: false
+
+Lint/InheritException:
+  Enabled: false
+
+Lint/SafeNavigationChain:
+  Enabled: false
+
+Lint/ElseLayout:
+  Exclude:
+    - 'language/if_spec.rb'
+
 Lint/EmptyExpression:
   Exclude:
     - 'language/**/*.rb'
@@ -67,6 +133,10 @@ Lint/EmptyWhen:
     - language/case_spec.rb
     - optional/capi/spec_helper.rb
 
+Lint/ErbNewArguments:
+  Exclude:
+    - 'library/erb/new_spec.rb'
+
 Lint/FormatParameterMismatch:
   Exclude:
     - 'core/kernel/shared/sprintf.rb'
@@ -77,12 +147,21 @@ Lint/NestedMethodDefinition:
     - language/def_spec.rb
     - language/fixtures/def.rb
 
+Lint/ShadowingOuterLocalVariable:
+  Exclude:
+    - 'core/binding/local_variables_spec.rb'
+    - 'core/kernel/local_variables_spec.rb'
+    - 'language/block_spec.rb'
+    - 'language/proc_spec.rb'
+
 Lint/UnreachableCode:
   Exclude:
     - 'core/enumerator/lazy/fixtures/classes.rb'
     - 'core/kernel/catch_spec.rb'
+    - 'core/kernel/raise_spec.rb'
     - 'core/kernel/throw_spec.rb'
     - 'language/break_spec.rb'
+    - 'language/optional_assignments_spec.rb'
     - 'language/fixtures/break.rb'
     - 'language/fixtures/break_lambda_toplevel.rb'
     - 'language/fixtures/break_lambda_toplevel_block.rb'
@@ -101,12 +180,20 @@ Lint/Debugger:
   Exclude:
     - 'core/binding/fixtures/irb.rb'
 
+Lint/Loop:
+  Enabled: false
+
+Style/BlockComments:
+  Enabled: true
+
 Style/Lambda:
   Enabled: true
   EnforcedStyle: literal
   Exclude:
     - 'language/lambda_spec.rb'
     - 'language/proc_spec.rb'
+    - 'language/numbered_parameters_spec.rb'
+    - 'language/it_parameter_spec.rb'
     - 'core/kernel/lambda_spec.rb'
 
 Style/EmptyLambdaParameter:
diff --git a/spec/ruby/.rubocop_todo.yml b/spec/ruby/.rubocop_todo.yml
index 261fde9e47..f998002c6d 100644
--- a/spec/ruby/.rubocop_todo.yml
+++ b/spec/ruby/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2018-04-03 22:23:59 +0900 using RuboCop version 0.54.0.
+# on 2026-05-29 08:10:07 UTC using RuboCop version 1.86.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -11,16 +11,22 @@ Lint/DuplicateCaseCondition:
   Exclude:
     - 'language/case_spec.rb'
 
-# Offense count: 6
+# Offense count: 20
 Lint/DuplicateMethods:
   Exclude:
     - 'core/array/fixtures/encoded_strings.rb'
     - 'core/method/fixtures/classes.rb'
+    - 'core/module/const_added_spec.rb'
+    - 'core/module/define_method_spec.rb'
     - 'core/module/fixtures/classes.rb'
+    - 'core/module/method_added_spec.rb'
+    - 'core/module/name_spec.rb'
+    - 'core/proc/new_spec.rb'
     - 'core/unboundmethod/fixtures/classes.rb'
     - 'fixtures/class.rb'
+    - 'language/assignments_spec.rb'
 
-# Offense count: 5
+# Offense count: 8
 Lint/EnsureReturn:
   Exclude:
     - 'language/fixtures/ensure.rb'
@@ -28,17 +34,21 @@ Lint/EnsureReturn:
     - 'language/return_spec.rb'
 
 # Offense count: 10
+Lint/FlipFlop:
+  Exclude:
+    - 'language/if_spec.rb'
+    - 'language/precedence_spec.rb'
+
+# Offense count: 10
 Lint/FloatOutOfRange:
   Exclude:
     - 'core/string/modulo_spec.rb'
 
-# Offense count: 29
-Lint/HandleExceptions:
-  Enabled: false
-
-# Offense count: 2
+# Offense count: 3
+# This cop supports safe autocorrection (--autocorrect).
 Lint/ImplicitStringConcatenation:
   Exclude:
+    - 'core/string/chilled_string_spec.rb'
     - 'language/string_spec.rb'
 
 # Offense count: 4
@@ -48,95 +58,75 @@ Lint/IneffectiveAccessModifier:
     - 'core/module/fixtures/classes.rb'
     - 'language/fixtures/private.rb'
 
-# Offense count: 6
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: runtime_error, standard_error
-Lint/InheritException:
-  Exclude:
-    - 'core/enumerator/lazy/fixtures/classes.rb'
-    - 'core/exception/fixtures/common.rb'
-    - 'core/module/fixtures/autoload_ex1.rb'
-
-# Offense count: 5
-# Cop supports --auto-correct.
+# Offense count: 12
+# This cop supports safe autocorrection (--autocorrect).
 Lint/LiteralInInterpolation:
   Exclude:
     - 'core/module/refine_spec.rb'
+    - 'core/string/shared/to_sym.rb'
+    - 'language/alias_spec.rb'
     - 'language/defined_spec.rb'
     - 'language/fixtures/squiggly_heredoc.rb'
-
-# Offense count: 16
-Lint/Loop:
-  Exclude:
-    - 'language/until_spec.rb'
-    - 'language/while_spec.rb'
+    - 'language/string_spec.rb'
+    - 'language/symbol_spec.rb'
+    - 'language/undef_spec.rb'
 
 # Offense count: 8
-# Cop supports --auto-correct.
-Lint/MultipleCompare:
+# This cop supports safe autocorrection (--autocorrect).
+Lint/MultipleComparison:
   Exclude:
     - 'language/precedence_spec.rb'
 
-# Offense count: 12
+# Offense count: 9
+# This cop supports safe autocorrection (--autocorrect).
 Lint/ParenthesesAsGroupedExpression:
   Exclude:
-    - 'core/string/fixtures/freeze_magic_comment.rb'
     - 'language/block_spec.rb'
-    - 'language/fixtures/send.rb'
     - 'language/method_spec.rb'
 
 # Offense count: 1
-# Cop supports --auto-correct.
-Lint/RedundantWithIndex:
-  Exclude:
-    - 'core/enumerator/with_index_spec.rb'
-
-# Offense count: 26
-Lint/RescueException:
-  Exclude:
-    - 'command_line/fixtures/debug_info.rb'
-    - 'core/dir/fileno_spec.rb'
-    - 'core/exception/cause_spec.rb'
-    - 'core/exception/no_method_error_spec.rb'
-    - 'core/kernel/fixtures/autoload_frozen.rb'
-    - 'core/module/autoload_spec.rb'
-    - 'core/mutex/sleep_spec.rb'
-    - 'core/process/euid_spec.rb'
-    - 'core/process/setsid_spec.rb'
-    - 'core/process/uid_spec.rb'
-    - 'core/thread/abort_on_exception_spec.rb'
-    - 'core/thread/shared/exit.rb'
-    - 'language/rescue_spec.rb'
-    - 'library/erb/filename_spec.rb'
+# This cop supports unsafe autocorrection (--autocorrect-all).
+# Configuration parameters: AllowedMethods, InferNonNilReceiver, AdditionalNilMethods.
+# AllowedMethods: instance_of?, kind_of?, is_a?, eql?, respond_to?, equal?
+# AdditionalNilMethods: present?, blank?, try, try!
+Lint/RedundantSafeNavigation:
+  Exclude:
+    - 'language/safe_navigator_spec.rb'
+    - 'language/fixtures/rescue_captures.rb'
 
 # Offense count: 2
-# Configuration parameters: IgnoreImplicitReferences.
-Lint/ShadowedArgument:
+# This cop supports safe autocorrection (--autocorrect).
+Lint/RedundantStringCoercion:
   Exclude:
-    - 'language/fixtures/super.rb'
+    - 'core/io/print_spec.rb'
 
-# Offense count: 10
-Lint/ShadowingOuterLocalVariable:
+# Offense count: 1
+# Configuration parameters: AllowRBSInlineAnnotation.
+Lint/SelfAssignment:
   Exclude:
-    - 'core/binding/local_variables_spec.rb'
-    - 'language/block_spec.rb'
-    - 'language/proc_spec.rb'
+    - 'core/gc/auto_compact_spec.rb'
 
-# Offense count: 2
-# Cop supports --auto-correct.
-Lint/StringConversionInInterpolation:
+# Offense count: 4
+# Configuration parameters: IgnoreImplicitReferences.
+Lint/ShadowedArgument:
   Exclude:
-    - 'core/io/print_spec.rb'
+    - 'language/fixtures/super.rb'
+
+# Offense count: 49
+# Configuration parameters: AllowComments, AllowNil.
+Lint/SuppressedException:
+  Enabled: false
 
 # Offense count: 9
+# Configuration parameters: AllowKeywordBlockArguments.
 Lint/UnderscorePrefixedVariableName:
   Exclude:
     - 'core/io/pipe_spec.rb'
     - 'core/io/popen_spec.rb'
     - 'language/block_spec.rb'
 
-# Offense count: 7
+# Offense count: 9
+# This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: ContextCreatingMethods, MethodCreatingMethods.
 Lint/UselessAccessModifier:
   Exclude:
@@ -144,13 +134,5 @@ Lint/UselessAccessModifier:
     - 'core/module/fixtures/classes.rb'
     - 'core/module/module_function_spec.rb'
     - 'core/module/private_class_method_spec.rb'
-    - 'core/module/private_spec.rb'
-    - 'core/module/protected_spec.rb'
-    - 'core/module/public_spec.rb'
+    - 'language/fixtures/def.rb'
     - 'language/fixtures/send.rb'
-
-# Offense count: 6186
-# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
-# URISchemes: http, https
-Metrics/LineLength:
-  Max: 588
diff --git a/spec/ruby/CONTRIBUTING.md b/spec/ruby/CONTRIBUTING.md
index 2f9b138372..a474e205f0 100644
--- a/spec/ruby/CONTRIBUTING.md
+++ b/spec/ruby/CONTRIBUTING.md
@@ -8,17 +8,19 @@ Spec are grouped in 5 separate top-level groups:
 
 * `command_line`: for the ruby executable command-line flags (`-v`, `-e`, etc)
 * `language`: for the language keywords and syntax constructs (`if`, `def`, `A::B`, etc)
-* `core`: for the core methods (`Fixnum#+`, `String#upcase`, no need to require anything)
+* `core`: for the core methods (`Integer#+`, `String#upcase`, no need to require anything)
 * `library`: for the standard libraries methods (`CSV.new`, `YAML.parse`, need to require the stdlib)
 * `optional/capi`: for functions available to the Ruby C-extension API
 
 The exact file for methods is decided by the `#owner` of a method, for instance for `#group_by`:
+
 ```ruby
 > [].method(:group_by)
 => #<Method: Array(Enumerable)#group_by>
 > [].method(:group_by).owner
 => Enumerable
 ```
+
 Which should therefore be specified in `core/enumerable/group_by_spec.rb`.
 
 ### MkSpec - a tool to generate the spec structure
@@ -53,12 +55,19 @@ which indicates the file was generated but the method unspecified.
 Here is a list of frequently-used matchers, which should be enough for most specs.
 There are a few extra specific matchers used in the couple specs that need it.
 
+The general idea is: add `.should` just before the predicate you expect to be truthy, and done!
+This works for most needs and provides a great error when it fails.
+It's immediately clear which method is used and there no need to remember a mapping like in RSpec between e.g. `eq` and `==`.
+See [this blog post](https://eregon.me/blog/2019/10/07/a-new-should-syntax.html) for the motivation behind that syntax.
+
+#### Comparison matchers
+
 ```ruby
 (1 + 2).should == 3 # Calls #==
 (1 + 2).should_not == 5
 
-File.should equal(File) # Calls #equal? (tests identity)
-(1 + 2).should eql(3) # Calls #eql? (Hash equality)
+File.should.equal?(File) # Calls #equal? (tests identity)
+(1 + 2).should.eql?(3) # Calls #eql? (Hash equality)
 
 1.should < 2
 2.should <= 2
@@ -66,32 +75,55 @@ File.should equal(File) # Calls #equal? (tests identity)
 4.should > 3
 
 "Hello".should =~ /l{2}/ # Calls #=~ (Regexp match)
+```
 
-[].should be_empty # Calls #empty?
-[1,2,3].should include(2) # Calls #include?
+#### Predicate matchers
+
+```ruby
+[].should.empty?
+[1,2,3].should.include?(2)
+
+"hello".should.start_with?("h")
+"hello".should.end_with?("o")
 
 (0.1 + 0.2).should be_close(0.3, TOLERANCE) # (0.2-0.1).abs < TOLERANCE
-(0.0/0.0).should be_nan # Calls Float#nan?
-(1.0/0.0).should be_positive_infinity
-(-1.0/0.0).should be_negative_infinity
+(0.0/0.0).should.nan?
+
+3.14.should.instance_of?(Float) # Calls #instance_of?
+3.14.should.is_a?(Numeric) # Calls #is_a?
 
-3.14.should be_an_instance_of(Float) # Calls #instance_of?
-3.14.should be_kind_of(Numeric) # Calls #is_a?
-Numeric.should be_ancestor_of(Float) # Float.ancestors.include?(Numeric)
+3.14.should.respond_to?(:to_i)
+Integer.should.method_defined?(:+, false)
+```
+
+#### Exception matchers
 
-3.14.should respond_to(:to_i) # Calls #respond_to?
-Fixnum.should have_instance_method(:+)
-Array.should have_method(:new)
-# Also have_constant, have_private_instance_method, have_singleton_method, etc
+```ruby
+-> {
+  raise "oops"
+}.should.raise(RuntimeError, /oops/)
 
 -> {
   raise "oops"
-}.should raise_error(RuntimeError, /oops/)
+}.should.raise(RuntimeError) { |e|
+  # Custom checks on the Exception object
+  e.message.should.include?("oops")
+  e.cause.should == nil
+}
+```
+
+##### `should_not.raise`
+
+**Avoid this!** Instead, use an expectation testing what the code in the lambda does.
+If an exception is raised, it will fail the example anyway.
+
+```ruby
+-> { ... }.should_not.raise
+```
 
-# To avoid! Instead, use an expectation testing what the code in the lambda does.
-# If an exception is raised, it will fail the example anyway.
--> { ... }.should_not raise_error
+#### Warning matcher
 
+```ruby
 -> {
   Fixnum
 }.should complain(/constant ::Fixnum is deprecated/) # Expect a warning
@@ -102,15 +134,21 @@ Array.should have_method(:new)
 Different guards are available as defined by mspec.
 Here is a list of the most commonly-used guards:
 
+#### Version guards
+
 ```ruby
-ruby_version_is ""..."2.4" do
-  # Specs for RUBY_VERSION < 2.4
+ruby_version_is ""..."3.2" do
+  # Specs for RUBY_VERSION < 3.2
 end
 
-ruby_version_is "2.4" do
-  # Specs for RUBY_VERSION >= 2.4
+ruby_version_is "3.2" do
+  # Specs for RUBY_VERSION >= 3.2
 end
+```
 
+#### Platform guards
+
+```ruby
 platform_is :windows do
   # Specs only valid on Windows
 end
@@ -125,34 +163,48 @@ end
 platform_is_not :linux, :darwin do # Not Linux and not Darwin
 end
 
-platform_is wordsize: 64 do
+platform_is pointer_size: 64 do
   # 64-bit platform
 end
 
 big_endian do
   # Big-endian platform
 end
+```
+
+#### Guard for bug
 
-# In case there is a bug in MRI but the expected behavior is obvious
-# First file a bug at https://bugs.ruby-lang.org/
-# It is better to use a ruby_version_is guard if there was a release with the fix
-ruby_bug '#13669', ''...'2.5' do
+In case there is a bug in MRI and the fix will be backported to previous versions.
+If it is not backported or not likely, use `ruby_version_is` instead.
+First, file a bug at https://bugs.ruby-lang.org/.
+The problem is `ruby_bug` would make non-MRI implementations fail this spec while MRI itself does not pass it, so it should only be used if the bug is/will be fixed and backported.
+Otherwise, non-MRI implementations would have to choose between being incompatible with the latest release of MRI (which has the bug) to pass the spec, or behave the same as the latest release of MRI (which has the bug) and fail the spec, both which make no sense.
+
+IOW, `ruby_bug '#NN', ''...'X.Y' do` is equivalent to `guard_not { RUBY_ENGINE == "ruby" && ruby_version_is ''...'X.Y' } do`. So it skips tests on MRI on specified versions (where a bug is present) and runs tests on alternative implementations only.
+
+```ruby
+ruby_bug '#13669', ''...'3.2' do
   it "works like this" do
     # Specify the expected behavior here, not the bug
   end
 end
+```
 
+#### Combining guards
 
-# Combining guards
-guard -> { platform_is :windows and ruby_version_is ""..."2.5" } do
-  # Windows and RUBY_VERSION < 2.5
+```ruby
+guard -> { platform_is :windows and ruby_version_is ""..."3.2" } do
+  # Windows and RUBY_VERSION < 3.2
 end
 
-guard_not -> { platform_is :windows and ruby_version_is ""..."2.5" } do
+guard_not -> { platform_is :windows and ruby_version_is ""..."3.2" } do
   # The opposite
 end
+```
+
+#### Custom guard
 
-# Custom guard
+```ruby
 max_uint = (1 << 32) - 1
 guard -> { max_uint <= fixnum_max } do
 end
@@ -160,6 +212,8 @@ end
 
 Custom guards are better than a simple `if` as they allow [mspec commands](https://github.com/ruby/mspec/issues/30#issuecomment-312487779) to work properly.
 
+#### Implementation-specific behaviors
+
 In general, the usage of guards should be minimized as possible.
 
 There are no guards to define implementation-specific behavior because
@@ -171,11 +225,11 @@ If an implementation does not support some feature, simply tag the related specs
 ### Shared Specs
 
 Often throughout Ruby, identical functionality is used by different methods and modules. In order
-to avoid duplication of specs, we have shared specs that are re-used in other specs.  The use is a
+to avoid duplication of specs, we have shared specs that are re-used in other specs. The use is a
 bit tricky however, so let's go over it.
 
 Commonly, if a shared spec is only reused within its own module, the shared spec will live within a
-shared directory inside that module's directory. For example, the `core/hash/shared/key.rb` spec is
+shared directory inside that module's directory. For example, the `core/hash/shared/iteration.rb` spec is
 only used by `Hash` specs, and so it lives inside `core/hash/shared/`.
 
 When a shared spec is used across multiple modules or classes, it lives within the `shared/` directory.
@@ -183,54 +237,54 @@ An example of this is the `shared/file/socket.rb` which is used by `core/file/so
 `core/filetest/socket_spec.rb`, and `core/file/state/socket_spec.rb` and so it lives in the root `shared/`.
 
 Defining a shared spec involves adding a `shared: true` option to the top-level `describe` block. This
-will signal not to run the specs directly by the runner.  Shared specs have access to two instance
+will signal not to run the specs directly by the runner. Shared specs have access to two instance
 variables from the implementor spec: `@method` and `@object`, which the implementor spec will pass in.
 
 Here's an example of a snippet of a shared spec and two specs which integrates it:
 
 ```ruby
-# core/hash/shared/key.rb
-describe :hash_key_p, shared: true do
-  it "returns true if the key's matching value was false" do
-    { xyz: false }.send(@method, :xyz).should == true
+# core/hash/shared/iteration.rb
+describe :hash_iteration_no_block, shared: true do
+  it "returns an Enumerator if called on a non-empty hash without a block" do
+    { 1 => 2 }.send(@method).should.instance_of?(Enumerator)
   end
 end
 
-# core/hash/key_spec.rb
-describe "Hash#key?" do
-  it_behaves_like :hash_key_p, :key?
+# core/hash/select_spec.rb
+describe "Hash#select" do
+  it_behaves_like :hash_iteration_no_block, :select
 end
 
-# core/hash/include_spec.rb
-describe "Hash#include?" do
-  it_behaves_like :hash_key_p, :include?
+# core/hash/reject_spec.rb
+describe "Hash#reject" do
+  it_behaves_like :hash_iteration_no_block, :reject
 end
 ```
 
-In the example, the first `describe` defines the shared spec `:hash_key_p`, which defines a spec that
-calls the `@method` method with an expectation.  In the implementor spec, we use `it_behaves_like` to
-integrate the shared spec.  `it_behaves_like` takes 3 parameters: the key of the shared spec, a method,
-and an object.  These last two parameters are accessible via `@method` and `@object` in the shared spec.
+In the example, the first `describe` defines the shared spec `:hash_iteration_no_block`, which defines a spec that
+calls the `@method` method with an expectation. In the implementor spec, we use `it_behaves_like` to
+integrate the shared spec. `it_behaves_like` takes 3 parameters: the key of the shared spec, a method,
+and an object. These last two parameters are accessible via `@method` and `@object` in the shared spec.
 
 Sometimes, shared specs require more context from the implementor class than a simple object. We can address
-this by passing a lambda as the method, which will have the scope of the implementor.  Here's an example of
+this by passing a lambda as the method, which will have the scope of the implementor. Here's an example of
 how this is used currently:
 
 ```ruby
 describe :kernel_sprintf, shared: true do
   it "raises TypeError exception if cannot convert to Integer" do
-    -> { @method.call("%b", Object.new) }.should raise_error(TypeError)
+    -> { @method.call("%b", Object.new) }.should.raise(TypeError)
   end
 end
 
 describe "Kernel#sprintf" do
-  it_behaves_like :kernel_sprintf, -> (format, *args) {
+  it_behaves_like :kernel_sprintf, -> format, *args {
     sprintf(format, *args)
   }
 end
 
 describe "Kernel.sprintf" do
-  it_behaves_like :kernel_sprintf, -> (format, *args) {
+  it_behaves_like :kernel_sprintf, -> format, *args {
     Kernel.sprintf(format, *args)
   }
 end
diff --git a/spec/ruby/README.md b/spec/ruby/README.md
index 980eaf034f..b259a97e21 100644
--- a/spec/ruby/README.md
+++ b/spec/ruby/README.md
@@ -1,11 +1,11 @@
 # The Ruby Spec Suite
 
-[![Build Status](https://travis-ci.org/ruby/spec.svg)](https://travis-ci.org/ruby/spec)
-[![Build Status](https://ci.appveyor.com/api/projects/status/1gs6f399320o44b1?svg=true)](https://ci.appveyor.com/project/eregon/spec-x948i)
-[![Gitter](https://badges.gitter.im/ruby/spec.svg)](https://gitter.im/ruby/spec)
+[![Actions Build Status](https://github.com/ruby/spec/workflows/CI/badge.svg)](https://github.com/ruby/spec/actions)
 
 The Ruby Spec Suite, abbreviated `ruby/spec`, is a test suite for the behavior of the Ruby programming language.
 
+### Description and Motivation
+
 It is not a standardized specification like the ISO one, and does not aim to become one.
 Instead, it is a practical tool to describe and test the behavior of Ruby with code.
 
@@ -17,39 +17,54 @@ Every example code has a textual description, which presents several advantages:
 
 The specs are written with syntax similar to RSpec 2.
 They are run with MSpec, the purpose-built framework for running the Ruby Spec Suite.
-For more information, see the [MSpec](http://github.com/ruby/mspec) project.
+For more information, see the [MSpec](https://github.com/ruby/mspec) project.
 
 The specs describe the [language syntax](language/), the [core library](core/), the [standard library](library/), the [C API for extensions](optional/capi) and the [command line flags](command_line/).
 The language specs are grouped by keyword while the core and standard library specs are grouped by class and method.
 
 ruby/spec is known to be tested in these implementations for every commit:
-* [MRI](http://rubyci.org/) on 30 platforms and 4 versions
+
+* [MRI](https://rubyci.org/) on 30 platforms and 4 versions
 * [JRuby](https://github.com/jruby/jruby/tree/master/spec/ruby) for both 1.7 and 9.x
-* [TruffleRuby](https://github.com/oracle/truffleruby/tree/master/spec/ruby)
+* [TruffleRuby](https://github.com/truffleruby/truffleruby/tree/master/spec/ruby)
 * [Opal](https://github.com/opal/opal/tree/master/spec)
+* [Artichoke](https://github.com/artichoke/spec/tree/artichoke-vendor)
 
-ruby/spec describes the behavior of Ruby 2.4 and more recent Ruby versions.
-More precisely, every latest stable MRI release should [pass](https://travis-ci.org/ruby/spec) all specs of ruby/spec (2.4.x, 2.5.x, 2.6.x, etc), and those are tested in TravisCI.
+ruby/spec describes the behavior of Ruby 3.3 and more recent Ruby versions.
+More precisely, every latest stable MRI release should [pass](https://github.com/ruby/spec/actions/workflows/ci.yml) all specs of ruby/spec (3.3.x, 3.4.x, etc), and those are tested in CI.
 
-The specs are synchronized both ways around once a month by @eregon between ruby/spec, MRI, JRuby and TruffleRuby.
+### Synchronization with Ruby Implementations
+
+The specs are synchronized both ways around once a month by @andrykonchin between ruby/spec, MRI, JRuby and TruffleRuby,
+using [this script](https://github.com/ruby/mspec/blob/master/tool/sync/sync-rubyspec.rb).
 Each of these repositories has a full copy of the specs under `spec/ruby` to ease editing specs.
 Any of these repositories can be used to add or edit specs, use what is most convenient for you.
 
-For *testing* a Ruby implementation, one should always test against the implementation's copy of the specs under `spec/ruby`, as that's what the Ruby implementation tests against in their CI.
+For *testing* the development version of a Ruby implementation, one should always test against that implementation's copy of the specs under `spec/ruby`, as that's what the Ruby implementation tests against in their CI.
 Also, this repository doesn't always contain the latest spec changes from MRI (it's synchronized monthly), and does not contain tags (specs marked as failing on that Ruby implementation).
-Running specs in a Ruby implementation can be done with:
+Running specs on a Ruby implementation can be done with:
 
-```
+```console
 $ cd ruby_implementation/spec/ruby
 # Add ../ruby_implementation/bin in PATH, or pass -t /path/to/bin/ruby
 $ ../mspec/bin/mspec
 ```
 
+### Specs for old Ruby versions
+
 For older specs try these commits:
+
 * Ruby 2.0.0-p647 - [Suite](https://github.com/ruby/spec/commit/245862558761d5abc676843ef74f86c9bcc8ea8d) using [MSpec](https://github.com/ruby/mspec/commit/f90efa068791064f955de7a843e96e2d7d3041c2) (may encounter 2 failures)
 * Ruby 2.1.9 - [Suite](https://github.com/ruby/spec/commit/f029e65241374386077ac500add557ae65069b55) using [MSpec](https://github.com/ruby/mspec/commit/55568ea3918c6380e64db8c567d732fa5781efed)
 * Ruby 2.2.10 - [Suite](https://github.com/ruby/spec/commit/cbaa0e412270c944df0c2532fc500c920dba0e92) using [MSpec](https://github.com/ruby/mspec/commit/d84d7668449e96856c5f6bac8cb1526b6d357ce3)
 * Ruby 2.3.8 - [Suite](https://github.com/ruby/spec/commit/dc733114d8ae66a3368ba3a98422c50147a76ba5) using [MSpec](https://github.com/ruby/mspec/commit/4599bc195fb109f2a482a01c32a7d659518369ea)
+* Ruby 2.4.10 - [Suite](https://github.com/ruby/spec/commit/bce4f2b81d6c31db67cf4d023a0625ceadde59bd) using [MSpec](https://github.com/ruby/mspec/commit/e7eb8aa4c26495b7b461e687d950b96eb08b3ff2)
+* Ruby 2.5.9 - [Suite](https://github.com/ruby/spec/commit/c503335d3d9f6ec6ef24de60a0716c34af69b64f) using [MSpec](https://github.com/ruby/mspec/commit/0091e8a62e954717cd54641f935eaf1403692041)
+* Ruby 2.6.10 - [Suite](https://github.com/ruby/spec/commit/aaf998fb8c92c4e63ad423a2e7ca6e6921818c6e) using [MSpec](https://github.com/ruby/mspec/commit/5e36c684e9e2b92b1187589bba1df22c640a8661)
+* Ruby 2.7.8 - [Suite](https://github.com/ruby/spec/commit/93787e6035c925b593a9c0c6fb0e7e07a6f1df1f) using [MSpec](https://github.com/ruby/mspec/commit/1d8cf64722d8a7529f7cd205be5f16a89b7a67fd)
+* Ruby 3.0.7 - [Suite](https://github.com/ruby/spec/commit/affef93d9940f615e4836f64b011da211f570913) using [MSpec](https://github.com/ruby/mspec/commit/0aabb3e548eb5ea6cad0125f8f46cee34542b6b7)
+* Ruby 3.1.6 - [Suite](https://github.com/ruby/spec/commit/ec960f2389d1c2265d32397fa8afa6d462014efc) using [MSpec](https://github.com/ruby/mspec/commit/484310dbed35b84c74484fd674602f88c42d063a)
+* Ruby 3.2.9 - [Suite](https://github.com/ruby/spec/commit/97f076242b7fc6e60703e6a6053365065cd6fc30) using [MSpec](https://github.com/ruby/mspec/commit/54704795e21128a930af2021c72c49cb87065134)
 
 ### Running the specs
 
@@ -61,7 +76,7 @@ Then move to it:
 
     $ cd spec
 
-Clone [MSpec](http://github.com/ruby/mspec):
+Clone [MSpec](https://github.com/ruby/mspec):
 
     $ git clone https://github.com/ruby/mspec.git ../mspec
 
@@ -116,16 +131,31 @@ MSpec can automatically add new top-level constants in this file with:
 
     $ CHECK_LEAKS=save mspec ../mspec/bin/mspec file
 
+### Running Specs on S390x CPU Architecture
+
+Run the specs with `DFLTCC=0` if you see failing specs related to the zlib library on s390x CPU architecture. The failures can happen with the zlib library applying the patch madler/zlib#410 to enable the deflate algorithm producing a different compressed byte stream.
+
+    $ DFLTCC=0 ../mspec/bin/mspec
+
 ### Contributing and Writing Specs
 
 See [CONTRIBUTING.md](https://github.com/ruby/spec/blob/master/CONTRIBUTING.md) for documentation about contributing and writing specs (guards, matchers, etc).
 
+### Dependencies
+
+These command-line executables are needed to run the specs.
+
+* `echo`
+* `stat` for `core/file/*time_spec.rb`
+* `find` for `core/file/fixtures/file_types.rb` (package `findutils`, not needed on Windows)
+
+The file `/etc/services` is required for socket specs (package `netbase` on Debian, not needed on Windows).
+
 ### Socket specs from rubysl-socket
 
-Most specs under `library/socket` were imported from [the rubysl-socket project](https://github.com/rubysl/rubysl-socket).
+Most specs under `library/socket` were imported from the rubysl-socket project (which is no longer on GitHub).
 The 3 copyright holders of rubysl-socket, Yorick Peterse, Chuck Remes and
-Brian Shirai, [agreed to relicense those specs](https://github.com/rubysl/rubysl-socket/issues/15)
-under the MIT license in ruby/spec.
+Brian Shirai, agreed to relicense those specs under the MIT license in ruby/spec.
 
 ### History and RubySpec
 
@@ -133,5 +163,5 @@ This project was originally born from [Rubinius](https://github.com/rubinius/rub
 The revision history of these specs is available [here](https://github.com/ruby/spec/blob/2b886623/CHANGES.before-2008-05-10).
 These specs were later extracted to their own project, RubySpec, with a specific vision and principles.
 At the end of 2014, Brian Shirai, the creator of RubySpec, decided to [end RubySpec](http://rubinius.com/2014/12/31/matz-s-ruby-developers-don-t-use-rubyspec/).
-A couple months later, the different repositories were merged and [the project was revived](http://eregon.github.io/rubyspec/2015/07/29/rubyspec-is-reborn.html).
+A couple months later, the different repositories were merged and [the project was revived](https://eregon.github.io/rubyspec/2015/07/29/rubyspec-is-reborn.html).
 On 12 January 2016, the name was changed to "The Ruby Spec Suite" for clarity and to let the RubySpec ideology rest in peace.
diff --git a/spec/ruby/bin/rubocop b/spec/ruby/bin/rubocop
new file mode 100755
index 0000000000..0937c47906
--- /dev/null
+++ b/spec/ruby/bin/rubocop
@@ -0,0 +1,12 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile do
+  source 'https://rubygems.org'
+
+  gem 'rubocop', '1.86.2'
+end
+
+exec(Gem.bin_path('rubocop', 'rubocop'), *ARGV)
diff --git a/spec/ruby/command_line/backtrace_limit_spec.rb b/spec/ruby/command_line/backtrace_limit_spec.rb
new file mode 100644
index 0000000000..4d57bc268b
--- /dev/null
+++ b/spec/ruby/command_line/backtrace_limit_spec.rb
@@ -0,0 +1,93 @@
+require_relative '../spec_helper'
+
+describe "The --backtrace-limit command line option" do
+  ruby_version_is ""..."3.4" do
+    it "limits top-level backtraces to a given number of entries" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "top 2>&1", exit_status: 1)
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+top
+/fixtures/backtrace.rb:2:in `a': oops (RuntimeError)
+\tfrom /fixtures/backtrace.rb:6:in `b'
+\tfrom /fixtures/backtrace.rb:10:in `c'
+\t ... 2 levels...
+      MSG
+    end
+
+    it "affects Exception#full_message" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "full_message 2>&1")
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+full_message
+/fixtures/backtrace.rb:2:in `a': oops (RuntimeError)
+\tfrom /fixtures/backtrace.rb:6:in `b'
+\tfrom /fixtures/backtrace.rb:10:in `c'
+\t ... 2 levels...
+      MSG
+    end
+
+    it "does not affect Exception#backtrace" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "backtrace 2>&1")
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+backtrace
+/fixtures/backtrace.rb:2:in `a'
+/fixtures/backtrace.rb:6:in `b'
+/fixtures/backtrace.rb:10:in `c'
+/fixtures/backtrace.rb:14:in `d'
+/fixtures/backtrace.rb:29:in `<main>'
+      MSG
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "limits top-level backtraces to a given number of entries" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "top 2>&1", exit_status: 1)
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+top
+/fixtures/backtrace.rb:2:in 'Object#a': oops (RuntimeError)
+\tfrom /fixtures/backtrace.rb:6:in 'Object#b'
+\tfrom /fixtures/backtrace.rb:10:in 'Object#c'
+\t ... 2 levels...
+      MSG
+    end
+
+    it "affects Exception#full_message" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "full_message 2>&1")
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+full_message
+/fixtures/backtrace.rb:2:in 'Object#a': oops (RuntimeError)
+\tfrom /fixtures/backtrace.rb:6:in 'Object#b'
+\tfrom /fixtures/backtrace.rb:10:in 'Object#c'
+\t ... 2 levels...
+      MSG
+    end
+
+    it "does not affect Exception#backtrace" do
+      file = fixture(__FILE__ , "backtrace.rb")
+      out = ruby_exe(file, options: "--backtrace-limit=2", args: "backtrace 2>&1")
+      out = out.gsub(__dir__, '')
+
+      out.should == <<-MSG
+backtrace
+/fixtures/backtrace.rb:2:in 'Object#a'
+/fixtures/backtrace.rb:6:in 'Object#b'
+/fixtures/backtrace.rb:10:in 'Object#c'
+/fixtures/backtrace.rb:14:in 'Object#d'
+/fixtures/backtrace.rb:29:in '<main>'
+      MSG
+    end
+  end
+end
diff --git a/spec/ruby/command_line/dash_0_spec.rb b/spec/ruby/command_line/dash_0_spec.rb
new file mode 100755
index 0000000000..2ce4f49b5e
--- /dev/null
+++ b/spec/ruby/command_line/dash_0_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../spec_helper'
+
+describe "The -0 command line option" do
+  it "sets $/ and $-0" do
+    ruby_exe("puts $/, $-0", options: "-072").should == ":\n:\n"
+  end
+
+  ruby_version_is "4.0" do
+    it "sets $/ and $-0 as a frozen string" do
+      ruby_exe("puts $/.frozen?, $-0.frozen?", options: "-072").should == "true\ntrue\n"
+    end
+  end
+end
diff --git a/spec/ruby/command_line/dash_a_spec.rb b/spec/ruby/command_line/dash_a_spec.rb
index 9ea135dc76..43d923ce16 100644
--- a/spec/ruby/command_line/dash_a_spec.rb
+++ b/spec/ruby/command_line/dash_a_spec.rb
@@ -6,13 +6,13 @@ describe "The -a command line option" do
   end
 
   it "runs the code in loop conditional on Kernel.gets()" do
-    ruby_exe("puts $F.last", options: "-n -a", escape: true,
+    ruby_exe("puts $F.last", options: "-n -a",
                              args: " < #{@names}").should ==
       "jones\nfield\ngrey\n"
   end
 
   it "sets $-a" do
-    ruby_exe("puts $-a", options: "-n -a", escape: true,
+    ruby_exe("puts $-a", options: "-n -a",
                          args: " < #{@names}").should ==
       "true\ntrue\ntrue\n"
   end
diff --git a/spec/ruby/command_line/dash_e_spec.rb b/spec/ruby/command_line/dash_e_spec.rb
index 9f600eb414..24ed34376d 100644
--- a/spec/ruby/command_line/dash_e_spec.rb
+++ b/spec/ruby/command_line/dash_e_spec.rb
@@ -23,7 +23,7 @@ describe "The -e command line option" do
 
   #needs to test return => LocalJumpError
 
-  describe "with -n and a Fixnum range" do
+  describe "with -n and an Integer range" do
     before :each do
       @script = "-ne 'print if %s' #{fixture(__FILE__, "conditional_range.txt")}"
     end
diff --git a/spec/ruby/command_line/dash_encoding_spec.rb b/spec/ruby/command_line/dash_encoding_spec.rb
index 36ce55af5f..5803d328c1 100644
--- a/spec/ruby/command_line/dash_encoding_spec.rb
+++ b/spec/ruby/command_line/dash_encoding_spec.rb
@@ -25,6 +25,12 @@ describe "The --encoding command line option" do
   end
 
   it "does not accept a third encoding" do
-    ruby_exe(@test_string, options: "--disable-gems --encoding big5:#{@enc2}:utf-32le", args: "2>&1").should =~ /extra argument for --encoding: utf-32le/
+    options = {
+      options: "--disable-gems --encoding big5:#{@enc2}:utf-32le",
+      args: "2>&1",
+      exit_status: 1
+    }
+
+    ruby_exe(@test_string, options).should =~ /extra argument for --encoding: utf-32le/
   end
 end
diff --git a/spec/ruby/command_line/dash_l_spec.rb b/spec/ruby/command_line/dash_l_spec.rb
new file mode 100644
index 0000000000..44a98445f3
--- /dev/null
+++ b/spec/ruby/command_line/dash_l_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../spec_helper'
+
+describe "The -l command line option" do
+  before :each do
+    @names  = fixture __FILE__, "full_names.txt"
+  end
+
+  it "chomps lines with default separator" do
+    ruby_exe('puts $_.end_with?("\n")', options: "-n -l",
+             args: " < #{@names}").should ==
+        "false\nfalse\nfalse\n"
+  end
+
+  it "chomps last line based on $/" do
+    ruby_exe('BEGIN { $/ = "ones\n" }; puts $_', options: "-W0 -n -l",
+             args: " < #{@names}").should ==
+        "alice j\nbob field\njames grey\n"
+  end
+
+  it "sets $\\ to the value of $/" do
+    ruby_exe("puts $\\ == $/", options: "-W0 -n -l",
+             args: " < #{@names}").should ==
+        "true\ntrue\ntrue\n"
+  end
+
+  it "sets $-l" do
+    ruby_exe("puts $-l", options: "-n -l",
+                         args: " < #{@names}").should ==
+      "true\ntrue\ntrue\n"
+  end
+end
diff --git a/spec/ruby/command_line/dash_n_spec.rb b/spec/ruby/command_line/dash_n_spec.rb
index 9d331d6065..1dd9379259 100644
--- a/spec/ruby/command_line/dash_n_spec.rb
+++ b/spec/ruby/command_line/dash_n_spec.rb
@@ -6,19 +6,19 @@ describe "The -n command line option" do
   end
 
   it "runs the code in loop conditional on Kernel.gets()" do
-    ruby_exe("puts $_", options: "-n", escape: true,
+    ruby_exe("puts $_", options: "-n",
                         args: " < #{@names}").should ==
       "alice\nbob\njames\n"
   end
 
   it "only evaluates BEGIN blocks once" do
-    ruby_exe("BEGIN { puts \"hi\" }; puts $_", options: "-n", escape: true,
+    ruby_exe("BEGIN { puts \"hi\" }; puts $_", options: "-n",
                                                args: " < #{@names}").should ==
       "hi\nalice\nbob\njames\n"
   end
 
   it "only evaluates END blocks once" do
-    ruby_exe("puts $_; END {puts \"bye\"}", options: "-n", escape: true,
+    ruby_exe("puts $_; END {puts \"bye\"}", options: "-n",
                                             args: " < #{@names}").should ==
       "alice\nbob\njames\nbye\n"
   end
@@ -29,7 +29,7 @@ describe "The -n command line option" do
     $total += 1
     END { puts $total }
     script
-    ruby_exe(script, options: "-n", escape: true,
+    ruby_exe(script, options: "-n",
                      args: " < #{@names}").should ==
       "3\n"
   end
diff --git a/spec/ruby/command_line/dash_p_spec.rb b/spec/ruby/command_line/dash_p_spec.rb
index 39827c3868..967e3796de 100644
--- a/spec/ruby/command_line/dash_p_spec.rb
+++ b/spec/ruby/command_line/dash_p_spec.rb
@@ -6,13 +6,13 @@ describe "The -p command line option" do
   end
 
   it "runs the code in loop conditional on Kernel.gets() and prints $_" do
-    ruby_exe("$_ = $_.upcase", options: "-p", escape: true,
+    ruby_exe("$_ = $_.upcase", options: "-p",
                                args: " < #{@names}").should ==
       "ALICE\nBOB\nJAMES\n"
   end
 
   it "sets $-p" do
-    ruby_exe("$_ = $-p", options: "-p", escape: true,
+    ruby_exe("$_ = $-p", options: "-p",
                          args: " < #{@names}").should ==
       "truetruetrue"
   end
diff --git a/spec/ruby/command_line/dash_r_spec.rb b/spec/ruby/command_line/dash_r_spec.rb
index b29895bd26..0de9ba2e24 100644
--- a/spec/ruby/command_line/dash_r_spec.rb
+++ b/spec/ruby/command_line/dash_r_spec.rb
@@ -7,7 +7,22 @@ describe "The -r command line option" do
   end
 
   it "requires the specified file" do
-    result = ruby_exe(@script, options: "-r #{@test_file}")
-    result.should include(@test_file + ".rb")
+    out = ruby_exe(@script, options: "-r #{@test_file}")
+    out.should.include?("REQUIRED")
+    out.should.include?(@test_file + ".rb")
+  end
+
+  it "requires the file before parsing the main script" do
+    out = ruby_exe(fixture(__FILE__, "bad_syntax.rb"), options: "-r #{@test_file}", args: "2>&1", exit_status: 1)
+    $?.should_not.success?
+    out.should.include?("REQUIRED")
+    out.should.include?("SyntaxError")
+  end
+
+  it "does not require the file if the main script file does not exist" do
+    out = `#{ruby_exe.to_a.join(' ')} -r #{@test_file} #{fixture(__FILE__, "does_not_exist.rb")} 2>&1`
+    $?.should_not.success?
+    out.should_not.include?("REQUIRED")
+    out.should.include?("No such file or directory")
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_e_spec.rb b/spec/ruby/command_line/dash_upper_e_spec.rb
index b3c6ce262b..5a83962583 100644
--- a/spec/ruby/command_line/dash_upper_e_spec.rb
+++ b/spec/ruby/command_line/dash_upper_e_spec.rb
@@ -31,6 +31,7 @@ describe "ruby -E" do
   it "raises a RuntimeError if used with -U" do
     ruby_exe("p 1",
              options: '-Eascii:ascii -U',
-             args: '2>&1').should =~ /RuntimeError/
+             args: '2>&1',
+             exit_status: 1).should =~ /RuntimeError/
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_f_spec.rb b/spec/ruby/command_line/dash_upper_f_spec.rb
index 967acc2ece..5c10a7140d 100644
--- a/spec/ruby/command_line/dash_upper_f_spec.rb
+++ b/spec/ruby/command_line/dash_upper_f_spec.rb
@@ -6,7 +6,7 @@ describe "the -F command line option" do
   end
 
   it "specifies the field separator pattern for -a" do
-    ruby_exe("puts $F[0]", options: "-naF:", escape: true,
+    ruby_exe("puts $F[0]", options: "-naF:",
                            args: " < #{@passwd}").should ==
       "nobody\nroot\ndaemon\n"
   end
diff --git a/spec/ruby/command_line/dash_upper_i_spec.rb b/spec/ruby/command_line/dash_upper_i_spec.rb
index 4cafb724e3..4005a27d23 100644
--- a/spec/ruby/command_line/dash_upper_i_spec.rb
+++ b/spec/ruby/command_line/dash_upper_i_spec.rb
@@ -6,7 +6,7 @@ describe "The -I command line option" do
   end
 
   it "adds the path to the load path ($:)" do
-    ruby_exe(@script, options: "-I fixtures").should include("fixtures")
+    ruby_exe(@script, options: "-I fixtures").should.include?("fixtures")
   end
 
   it "adds the path at the front of $LOAD_PATH" do
@@ -18,16 +18,16 @@ describe "The -I command line option" do
       idx.should < 2
       idx.should < lines.size-1
     else
-      lines[0].should include("fixtures")
+      lines[0].should.include?("fixtures")
     end
   end
 
   it "adds the path expanded from CWD to $LOAD_PATH" do
-    ruby_exe(@script, options: "-I fixtures").lines.should include "#{Dir.pwd}/fixtures\n"
+    ruby_exe(@script, options: "-I fixtures").lines.should.include? "#{Dir.pwd}/fixtures\n"
   end
 
   it "expands a path from CWD even if it does not exist" do
-    ruby_exe(@script, options: "-I not_exist/not_exist").lines.should include "#{Dir.pwd}/not_exist/not_exist\n"
+    ruby_exe(@script, options: "-I not_exist/not_exist").lines.should.include? "#{Dir.pwd}/not_exist/not_exist\n"
   end
 end
 
@@ -45,7 +45,7 @@ platform_is_not :windows do
     end
 
     it "does not expand symlinks" do
-      ruby_exe(@script, options: "-I #{@symlink}").lines.should include "#{@symlink}\n"
+      ruby_exe(@script, options: "-I #{@symlink}").lines.should.include? "#{@symlink}\n"
     end
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_k_spec.rb b/spec/ruby/command_line/dash_upper_k_spec.rb
index a060eab793..7e71532295 100644
--- a/spec/ruby/command_line/dash_upper_k_spec.rb
+++ b/spec/ruby/command_line/dash_upper_k_spec.rb
@@ -58,8 +58,8 @@ describe 'The -K command line option' do
   end
 
   it "ignores unknown codes" do
-    locale = Encoding.find('locale')
+    external = Encoding.find('external')
     ruby_exe(@test_string, options: '-KZ').should ==
-      [Encoding::UTF_8.name, locale.name, nil].inspect
+      [Encoding::UTF_8.name, external.name, nil].inspect
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_s_spec.rb b/spec/ruby/command_line/dash_upper_s_spec.rb
index 3a28fa2ad2..71c6016659 100644
--- a/spec/ruby/command_line/dash_upper_s_spec.rb
+++ b/spec/ruby/command_line/dash_upper_s_spec.rb
@@ -2,7 +2,8 @@ require_relative '../spec_helper'
 
 describe 'The -S command line option' do
   before :each do
-    @path = [ENV['PATH'], fixture(__FILE__, "bin")].join(':')
+    @bin = fixture(__FILE__, "bin")
+    @path = [ENV['PATH'], @bin].join(File::PATH_SEPARATOR)
   end
 
   platform_is_not :windows do
@@ -10,20 +11,57 @@ describe 'The -S command line option' do
     # and MRI shows warning when including world writable path in ENV['PATH'].
     # This is why we are using /success$/ matching in the following cases.
 
+    it "runs launcher found in RUBYPATH, but only code after the first /\#!.*ruby.*/-ish line in target file" do
+      result = ruby_exe(nil, options: '-S hybrid_launcher.sh', env: { 'RUBYPATH' => @bin }, args: '2>&1')
+      result.should =~ /success$/
+    end
+
     it "runs launcher found in PATH, but only code after the first /\#!.*ruby.*/-ish line in target file" do
       result = ruby_exe(nil, options: '-S hybrid_launcher.sh', env: { 'PATH' => @path }, args: '2>&1')
       result.should =~ /success$/
     end
 
+    it "runs launcher found in RUBYPATH" do
+      result = ruby_exe(nil, options: '-S launcher.rb', env: { 'RUBYPATH' => @bin }, args: '2>&1')
+      result.should =~ /success$/
+    end
+
     it "runs launcher found in PATH" do
       result = ruby_exe(nil, options: '-S launcher.rb', env: { 'PATH' => @path }, args: '2>&1')
       result.should =~ /success$/
     end
 
+    it "runs launcher found in RUBYPATH and sets the exit status to 1 if it fails" do
+      result = ruby_exe(nil, options: '-S dash_s_fail', env: { 'RUBYPATH' => @bin }, args: '2>&1', exit_status: 1)
+      result.should =~ /\bdie\b/
+      $?.exitstatus.should == 1
+    end
+
     it "runs launcher found in PATH and sets the exit status to 1 if it fails" do
-      result = ruby_exe(nil, options: '-S dash_s_fail', env: { 'PATH' => @path }, args: '2>&1')
+      result = ruby_exe(nil, options: '-S dash_s_fail', env: { 'PATH' => @path }, args: '2>&1', exit_status: 1)
       result.should =~ /\bdie\b/
       $?.exitstatus.should == 1
     end
+
+    ruby_version_is "4.1" do
+      describe "if the script name contains separator" do
+        before(:each) do
+          @bin = File.dirname(@bin)
+          @path = [ENV['PATH'], @bin].join(File::PATH_SEPARATOR)
+        end
+
+        it "does not search launcher in RUBYPATH" do
+          result = ruby_exe(nil, options: '-S bin/launcher.rb', env: { 'RUBYPATH' => @bin }, args: '2>&1', exit_status: 1)
+          result.should =~ /LoadError/
+          $?.should_not.success?
+        end
+
+        it "does not search launcher in PATH" do
+          result = ruby_exe(nil, options: '-S bin/launcher.rb', env: { 'PATH' => @path }, args: '2>&1', exit_status: 1)
+          result.should =~ /LoadError/
+          $?.should_not.success?
+        end
+      end
+    end
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_u_spec.rb b/spec/ruby/command_line/dash_upper_u_spec.rb
index 2546b5b9f4..2c210eb603 100644
--- a/spec/ruby/command_line/dash_upper_u_spec.rb
+++ b/spec/ruby/command_line/dash_upper_u_spec.rb
@@ -2,42 +2,51 @@ require_relative '../spec_helper'
 
 describe "ruby -U" do
   it "sets Encoding.default_internal to UTF-8" do
-     ruby_exe('print Encoding.default_internal.name',
-              options: '-U').should == 'UTF-8'
+    ruby_exe('print Encoding.default_internal.name',
+             options: '-U').should == 'UTF-8'
+  end
+
+  it "sets Encoding.default_internal to UTF-8 when RUBYOPT is empty or only spaces" do
+    ruby_exe('p Encoding.default_internal',
+             options: '-U', env: { 'RUBYOPT' => '' }).should == "#<Encoding:UTF-8>\n"
+    ruby_exe('p Encoding.default_internal',
+             options: '-U', env: { 'RUBYOPT' => '  ' }).should == "#<Encoding:UTF-8>\n"
   end
 
   it "does nothing different if specified multiple times" do
-     ruby_exe('print Encoding.default_internal.name',
-              options: '-U -U').should == 'UTF-8'
+    ruby_exe('print Encoding.default_internal.name',
+             options: '-U -U').should == 'UTF-8'
   end
 
   it "is overruled by Encoding.default_internal=" do
-     ruby_exe('Encoding.default_internal="ascii"; print Encoding.default_internal.name',
-              options: '-U').should == 'US-ASCII'
+    ruby_exe('Encoding.default_internal="ascii"; print Encoding.default_internal.name',
+             options: '-U').should == 'US-ASCII'
   end
 
   it "does not affect the default external encoding" do
-     ruby_exe('Encoding.default_external="ascii"; print Encoding.default_external.name',
-              options: '-U').should == 'US-ASCII'
+    ruby_exe('Encoding.default_external="ascii"; print Encoding.default_external.name',
+             options: '-U').should == 'US-ASCII'
   end
 
   it "does not affect the source encoding" do
-     ruby_exe("print __ENCODING__.name",
-              options: '-U -KE').should == 'EUC-JP'
-     ruby_exe("print __ENCODING__.name",
-              options: '-KE -U').should == 'EUC-JP'
+    ruby_exe("print __ENCODING__.name",
+             options: '-U -KE').should == 'EUC-JP'
+    ruby_exe("print __ENCODING__.name",
+             options: '-KE -U').should == 'EUC-JP'
   end
 
   # I assume IO redirection will break on Windows...
   it "raises a RuntimeError if used with -Eext:int" do
     ruby_exe("p 1",
              options: '-U -Eascii:ascii',
-             args: '2>&1').should =~ /RuntimeError/
+             args: '2>&1',
+             exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError if used with -E:int" do
     ruby_exe("p 1",
              options: '-U -E:ascii',
-             args: '2>&1').should =~ /RuntimeError/
+             args: '2>&1',
+             exit_status: 1).should =~ /RuntimeError/
   end
 end
diff --git a/spec/ruby/command_line/dash_upper_w_spec.rb b/spec/ruby/command_line/dash_upper_w_spec.rb
index 31bb976ad2..4019510d42 100644
--- a/spec/ruby/command_line/dash_upper_w_spec.rb
+++ b/spec/ruby/command_line/dash_upper_w_spec.rb
@@ -18,3 +18,27 @@ end
 describe "The -W command line option with 2" do
   it_behaves_like :command_line_verbose, "-W2"
 end
+
+describe "The -W command line option with :deprecated" do
+  it "enables deprecation warnings" do
+    ruby_exe('p Warning[:deprecated]', options: '-W:deprecated').should == "true\n"
+  end
+end
+
+describe "The -W command line option with :no-deprecated" do
+  it "suppresses deprecation warnings" do
+    ruby_exe('p Warning[:deprecated]', options: '-w -W:no-deprecated').should == "false\n"
+  end
+end
+
+describe "The -W command line option with :experimental" do
+  it "enables experimental warnings" do
+    ruby_exe('p Warning[:experimental]', options: '-W:experimental').should == "true\n"
+  end
+end
+
+describe "The -W command line option with :no-experimental" do
+  it "suppresses experimental warnings" do
+    ruby_exe('p Warning[:experimental]', options: '-w -W:no-experimental').should == "false\n"
+  end
+end
diff --git a/spec/ruby/command_line/dash_v_spec.rb b/spec/ruby/command_line/dash_v_spec.rb
index 04d684fdad..6a4f7d3a15 100644
--- a/spec/ruby/command_line/dash_v_spec.rb
+++ b/spec/ruby/command_line/dash_v_spec.rb
@@ -6,7 +6,10 @@ describe "The -v command line option" do
 
   describe "when used alone" do
     it "prints version and ends" do
-      ruby_exe(nil, args: '-v').should include(RUBY_DESCRIPTION)
-    end
+      ruby_exe(nil, args: '-v').gsub("+PRISM ", "").should.include?(RUBY_DESCRIPTION.gsub("+PRISM ", ""))
+    end unless (defined?(RubyVM::YJIT) && RubyVM::YJIT.enabled?) ||
+               (defined?(RubyVM::RJIT) && RubyVM::RJIT.enabled?) ||
+               (ENV['RUBY_GC_LIBRARY'] && ENV['RUBY_GC_LIBRARY'].length > 0) ||
+               (ENV['RUBY_MN_THREADS'] == '1')
   end
 end
diff --git a/spec/ruby/command_line/dash_w_spec.rb b/spec/ruby/command_line/dash_w_spec.rb
index 1d93e0347b..f310dca3ed 100644
--- a/spec/ruby/command_line/dash_w_spec.rb
+++ b/spec/ruby/command_line/dash_w_spec.rb
@@ -3,4 +3,8 @@ require_relative 'shared/verbose'
 
 describe "The -w command line option" do
   it_behaves_like :command_line_verbose, "-w"
+
+  it "enables both deprecated and experimental warnings" do
+    ruby_exe('p Warning[:deprecated]; p Warning[:experimental]', options: '-w').should == "true\ntrue\n"
+  end
 end
diff --git a/spec/ruby/command_line/dash_x_spec.rb b/spec/ruby/command_line/dash_x_spec.rb
index eb89db0144..38f97a5ab1 100644
--- a/spec/ruby/command_line/dash_x_spec.rb
+++ b/spec/ruby/command_line/dash_x_spec.rb
@@ -9,8 +9,8 @@ describe "The -x command line option" do
 
   it "fails when /\#!.*ruby.*/-ish line in target file is not found" do
     bad_embedded_ruby = fixture __FILE__, "bin/bad_embedded_ruby.txt"
-    result = ruby_exe(bad_embedded_ruby, options: '-x', args: '2>&1')
-    result.should include "no Ruby script found in input"
+    result = ruby_exe(bad_embedded_ruby, options: '-x', args: '2>&1', exit_status: 1)
+    result.should.include? "no Ruby script found in input"
   end
 
   it "behaves as -x was set when non-ruby shebang is encountered on first line" do
diff --git a/spec/ruby/command_line/error_message_spec.rb b/spec/ruby/command_line/error_message_spec.rb
index 5fee3ead44..157cb8969c 100644
--- a/spec/ruby/command_line/error_message_spec.rb
+++ b/spec/ruby/command_line/error_message_spec.rb
@@ -2,10 +2,15 @@ require_relative '../spec_helper'
 
 describe "The error message caused by an exception" do
   it "is not printed to stdout" do
-    out = ruby_exe("this_does_not_exist", args: "2> #{File::NULL}")
-    out.chomp.empty?.should == true
+    out = ruby_exe("this_does_not_exist", args: "2> #{File::NULL}", exit_status: 1)
+    out.chomp.should.empty?
 
-    out = ruby_exe("end #syntax error", args: "2> #{File::NULL}")
-    out.chomp.empty?.should == true
+    out = ruby_exe("end #syntax error", args: "2> #{File::NULL}", exit_status: 1)
+    out.chomp.should.empty?
+  end
+
+  it "is not modified with extra escaping of control characters and backslashes" do
+    out = ruby_exe('raise "\e[31mRed\e[0m error\\\\message"', args: "2>&1", exit_status: 1)
+    out.chomp.should.include?("\e[31mRed\e[0m error\\message")
   end
 end
diff --git a/spec/ruby/command_line/feature_spec.rb b/spec/ruby/command_line/feature_spec.rb
index 02571ee8c6..0a3252b88d 100644
--- a/spec/ruby/command_line/feature_spec.rb
+++ b/spec/ruby/command_line/feature_spec.rb
@@ -1,6 +1,12 @@
 require_relative '../spec_helper'
 
 describe "The --enable and --disable flags" do
+  before :all do
+    # Since some specs disable reading RUBYOPT, we instead pass its contents as :options for those specs
+    rubyopt = [ENV["RUBYOPT"]]
+    rubyopt << ENV["#{RUBY_ENGINE.upcase}OPT"] unless RUBY_ENGINE == 'ruby'
+    @rubyopt = RUBY_ENGINE == "ruby" ? "" : rubyopt.compact.join(" ")
+  end
 
   it "can be used with gems" do
     ruby_exe("p defined?(Gem)", options: "--enable=gems").chomp.should == "\"constant\""
@@ -25,9 +31,9 @@ describe "The --enable and --disable flags" do
 
   it "can be used with rubyopt" do
     ruby_exe("p $VERBOSE", options: "--enable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
-    ruby_exe("p $VERBOSE", options: "--disable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+    ruby_exe("p $VERBOSE", options: "#{@rubyopt} --disable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
     ruby_exe("p $VERBOSE", options: "--enable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
-    ruby_exe("p $VERBOSE", options: "--disable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+    ruby_exe("p $VERBOSE", options: "#{@rubyopt} --disable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
   end
 
   it "can be used with frozen-string-literal" do
@@ -37,20 +43,29 @@ describe "The --enable and --disable flags" do
     ruby_exe("p 'foo'.frozen?", options: "--disable-frozen-string-literal").chomp.should == "false"
   end
 
-  it "can be used with all" do
+  # frequently hangs for >60s on GitHub Actions macos-latest
+  # MinGW's YJIT support seems broken
+  platform_is_not :darwin, :mingw do
+    it "can be used with all for enable" do
+      e = "p [defined?(Gem), defined?(DidYouMean), $VERBOSE, 'foo'.frozen?]"
+      env = {'RUBYOPT' => '-w'}
+      # Use a single variant here because it can be quite slow as it might enable jit, etc
+      ruby_exe(e, options: "--enable-all", env: env).chomp.should == "[\"constant\", \"constant\", true, true]"
+    end unless defined?(RubyVM::YJIT) && defined?(RubyVM::ZJIT) && RubyVM::ZJIT.enabled? # You're not supposed to enable YJIT with --enable-all when ZJIT options are passed.
+  end
+
+  it "can be used with all for disable" do
     e = "p [defined?(Gem), defined?(DidYouMean), $VERBOSE, 'foo'.frozen?]"
     env = {'RUBYOPT' => '-w'}
-    ruby_exe(e, options: "--enable=all", env: env).chomp.should == "[\"constant\", \"constant\", true, true]"
-    ruby_exe(e, options: "--enable-all", env: env).chomp.should == "[\"constant\", \"constant\", true, true]"
-    ruby_exe(e, options: "--disable=all", env: env).chomp.should == "[nil, nil, false, false]"
-    ruby_exe(e, options: "--disable-all", env: env).chomp.should == "[nil, nil, false, false]"
+    ruby_exe(e, options: "#{@rubyopt} --disable=all", env: env).chomp.should == "[nil, nil, false, false]"
+    ruby_exe(e, options: "#{@rubyopt} --disable-all", env: env).chomp.should == "[nil, nil, false, false]"
   end
 
   it "prints a warning for unknown features" do
-    ruby_exe("p 14", options: "--enable=ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --enable')
-    ruby_exe("p 14", options: "--disable=ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --disable')
-    ruby_exe("p 14", options: "--enable-ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --enable')
-    ruby_exe("p 14", options: "--disable-ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --disable')
+    ruby_exe("p 14", options: "--enable=ruby-spec-feature-does-not-exist 2>&1").chomp.should.include?('warning: unknown argument for --enable')
+    ruby_exe("p 14", options: "--disable=ruby-spec-feature-does-not-exist 2>&1").chomp.should.include?('warning: unknown argument for --disable')
+    ruby_exe("p 14", options: "--enable-ruby-spec-feature-does-not-exist 2>&1").chomp.should.include?('warning: unknown argument for --enable')
+    ruby_exe("p 14", options: "--disable-ruby-spec-feature-does-not-exist 2>&1").chomp.should.include?('warning: unknown argument for --disable')
   end
 
 end
diff --git a/spec/ruby/command_line/fixtures/backtrace.rb b/spec/ruby/command_line/fixtures/backtrace.rb
new file mode 100644
index 0000000000..99acae95c8
--- /dev/null
+++ b/spec/ruby/command_line/fixtures/backtrace.rb
@@ -0,0 +1,35 @@
+def a
+  raise 'oops'
+end
+
+def b
+  a
+end
+
+def c
+  b
+end
+
+def d
+  c
+end
+
+arg = ARGV.first
+$stderr.puts arg
+
+case arg
+when 'full_message'
+  begin
+    d
+  rescue => exc
+    puts exc.full_message
+  end
+when 'backtrace'
+  begin
+    d
+  rescue => exc
+    puts exc.backtrace
+  end
+else
+  d
+end
diff --git a/spec/ruby/command_line/fixtures/bin/bad_embedded_ruby.txt b/spec/ruby/command_line/fixtures/bin/bad_embedded_ruby.txt
index a2b7ad085f..61b946977a 100644
--- a/spec/ruby/command_line/fixtures/bin/bad_embedded_ruby.txt
+++ b/spec/ruby/command_line/fixtures/bin/bad_embedded_ruby.txt
@@ -1,3 +1,3 @@
-@@@This line is not value Ruby
+@@@This line is not valid Ruby
 #!rub_y
 puts 'success'
diff --git a/spec/ruby/command_line/fixtures/bin/embedded_ruby.txt b/spec/ruby/command_line/fixtures/bin/embedded_ruby.txt
index c556bf0b71..0ec0f358db 100644
--- a/spec/ruby/command_line/fixtures/bin/embedded_ruby.txt
+++ b/spec/ruby/command_line/fixtures/bin/embedded_ruby.txt
@@ -1,3 +1,3 @@
-@@@This line is not value Ruby
+@@@This line is not valid Ruby
 #!ruby
-puts 'success'
-\ No newline at end of file
+puts 'success'
diff --git a/spec/ruby/command_line/fixtures/bin/hybrid_launcher.sh b/spec/ruby/command_line/fixtures/bin/hybrid_launcher.sh
index 0eede2a99f..fd3249f0e5 100644
--- a/spec/ruby/command_line/fixtures/bin/hybrid_launcher.sh
+++ b/spec/ruby/command_line/fixtures/bin/hybrid_launcher.sh
@@ -1,4 +1,4 @@
 #!/usr/bin/env bash
-exec somehow this file
+echo 'error' && exit 1
 #!ruby
 puts 'success'
diff --git a/spec/ruby/command_line/fixtures/debug_info.rb b/spec/ruby/command_line/fixtures/debug_info.rb
index ee607910c0..f02b041920 100644
--- a/spec/ruby/command_line/fixtures/debug_info.rb
+++ b/spec/ruby/command_line/fixtures/debug_info.rb
@@ -1,4 +1,3 @@
-# frozen_string_literal: true
 a = 'string'
 b = a
 c = b
diff --git a/spec/ruby/command_line/fixtures/freeze_flag_required_diff_enc.rb b/spec/ruby/command_line/fixtures/freeze_flag_required_diff_enc.rb
index fa348d59e7..df4b952c46 100644
--- a/spec/ruby/command_line/fixtures/freeze_flag_required_diff_enc.rb
+++ b/spec/ruby/command_line/fixtures/freeze_flag_required_diff_enc.rb
diff --git a/spec/ruby/command_line/fixtures/freeze_flag_two_literals.rb b/spec/ruby/command_line/fixtures/freeze_flag_two_literals.rb
index 074092c9d9..f5547a5bae 100644
--- a/spec/ruby/command_line/fixtures/freeze_flag_two_literals.rb
+++ b/spec/ruby/command_line/fixtures/freeze_flag_two_literals.rb
@@ -1 +1 @@
-p "abc".object_id == "abc".object_id
+p "abc".equal?("abc")
diff --git a/spec/ruby/command_line/fixtures/string_literal_frozen_comment.rb b/spec/ruby/command_line/fixtures/string_literal_frozen_comment.rb
new file mode 100644
index 0000000000..fb84b546c0
--- /dev/null
+++ b/spec/ruby/command_line/fixtures/string_literal_frozen_comment.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+frozen = "test".frozen?
+interned = "test".equal?("test")
+puts "frozen:#{frozen} interned:#{interned}"
diff --git a/spec/ruby/command_line/fixtures/string_literal_mutable_comment.rb b/spec/ruby/command_line/fixtures/string_literal_mutable_comment.rb
new file mode 100644
index 0000000000..381a742001
--- /dev/null
+++ b/spec/ruby/command_line/fixtures/string_literal_mutable_comment.rb
@@ -0,0 +1,4 @@
+# frozen_string_literal: false
+frozen = "test".frozen?
+interned = "test".equal?("test")
+puts "frozen:#{frozen} interned:#{interned}"
diff --git a/spec/ruby/command_line/fixtures/string_literal_raw.rb b/spec/ruby/command_line/fixtures/string_literal_raw.rb
new file mode 100644
index 0000000000..56b1841296
--- /dev/null
+++ b/spec/ruby/command_line/fixtures/string_literal_raw.rb
@@ -0,0 +1,3 @@
+frozen = "test".frozen?
+interned = "test".equal?("test")
+puts "frozen:#{frozen} interned:#{interned}"
diff --git a/spec/ruby/command_line/fixtures/test_file.rb b/spec/ruby/command_line/fixtures/test_file.rb
index 961e3c0b0c..30a832299e 100644
--- a/spec/ruby/command_line/fixtures/test_file.rb
+++ b/spec/ruby/command_line/fixtures/test_file.rb
@@ -1 +1 @@
-"test file"
+puts "REQUIRED"
diff --git a/spec/ruby/command_line/frozen_strings_spec.rb b/spec/ruby/command_line/frozen_strings_spec.rb
index 647b69daed..32ff7d0371 100644
--- a/spec/ruby/command_line/frozen_strings_spec.rb
+++ b/spec/ruby/command_line/frozen_strings_spec.rb
@@ -19,11 +19,76 @@ describe "The --enable-frozen-string-literal flag causes string literals to" do
   end
 end
 
+describe "The --disable-frozen-string-literal flag causes string literals to" do
+
+  it "produce a different object each time" do
+    ruby_exe(fixture(__FILE__, "freeze_flag_one_literal.rb"), options: "--disable-frozen-string-literal").chomp.should == "false"
+  end
+
+end
+
+describe "With neither --enable-frozen-string-literal nor --disable-frozen-string-literal flag set" do
+  before do
+    # disable --enable-frozen-string-literal and --disable-frozen-string-literal passed in $RUBYOPT
+    @rubyopt = ENV["RUBYOPT"]
+    ENV["RUBYOPT"] = ""
+  end
+
+  after do
+    ENV["RUBYOPT"] = @rubyopt
+  end
+
+  it "produce a different object each time" do
+    ruby_exe(fixture(__FILE__, "freeze_flag_one_literal.rb")).chomp.should == "false"
+  end
+
+  context "if file has no frozen_string_literal comment" do
+    it "produce different mutable strings each time" do
+      ruby_exe(fixture(__FILE__, "string_literal_raw.rb")).chomp.should == "frozen:false interned:false"
+    end
+
+    guard -> { ruby_version_is "3.4" and !"test".frozen? } do
+      it "complain about modification of produced mutable strings" do
+        -> { eval(<<~RUBY) }.should complain(/warning: literal string will be frozen in the future \(run with --debug-frozen-string-literal for more information\)/)
+          "test" << "!"
+        RUBY
+      end
+
+      it "does not complain about modification if Warning[:deprecated] is false" do
+        deprecated = Warning[:deprecated]
+        Warning[:deprecated] = false
+        -> { eval(<<~RUBY) }.should_not complain
+          "test" << "!"
+        RUBY
+      ensure
+        Warning[:deprecated] = deprecated
+      end
+    end
+  end
+
+  it "if file has frozen_string_literal:true comment produce same frozen strings each time" do
+    ruby_exe(fixture(__FILE__, "string_literal_frozen_comment.rb")).chomp.should == "frozen:true interned:true"
+  end
+
+  it "if file has frozen_string_literal:false comment produce different mutable strings each time" do
+    ruby_exe(fixture(__FILE__, "string_literal_mutable_comment.rb")).chomp.should == "frozen:false interned:false"
+  end
+end
+
 describe "The --debug flag produces" do
   it "debugging info on attempted frozen string modification" do
-    error_str = ruby_exe(fixture(__FILE__, 'debug_info.rb'), options: '--debug',  args: "2>&1")
-    error_str.should include("can't modify frozen String")
-    error_str.should include("created at")
-    error_str.should include("command_line/fixtures/debug_info.rb:2")
+    error_str = ruby_exe(fixture(__FILE__, 'debug_info.rb'), options: '--enable-frozen-string-literal --debug',  args: "2>&1")
+    error_str.should.include?("can't modify frozen String")
+    error_str.should.include?("created at")
+    error_str.should.include?("command_line/fixtures/debug_info.rb:1")
+  end
+
+  guard -> { ruby_version_is "3.4" and !"test".frozen? } do
+    it "debugging info on mutating chilled string" do
+      error_str = ruby_exe(fixture(__FILE__, 'debug_info.rb'), options: '-w --debug',  args: "2>&1")
+      error_str.should.include?("literal string will be frozen in the future")
+      error_str.should.include?("the string was created here")
+      error_str.should.include?("command_line/fixtures/debug_info.rb:1")
+    end
   end
 end
diff --git a/spec/ruby/command_line/rubylib_spec.rb b/spec/ruby/command_line/rubylib_spec.rb
index b45919b997..1bedd146e3 100644
--- a/spec/ruby/command_line/rubylib_spec.rb
+++ b/spec/ruby/command_line/rubylib_spec.rb
@@ -14,15 +14,15 @@ describe "The RUBYLIB environment variable" do
     dir = tmp("rubylib/incl")
     ENV["RUBYLIB"] = @pre + dir
     paths = ruby_exe("puts $LOAD_PATH").lines.map(&:chomp)
-    paths.should include(dir)
+    paths.should.include?(dir)
   end
 
   it "adds a File::PATH_SEPARATOR-separated list of directories to $LOAD_PATH" do
     dir1, dir2 = tmp("rubylib/incl1"), tmp("rubylib/incl2")
     ENV["RUBYLIB"] = @pre + "#{dir1}#{File::PATH_SEPARATOR}#{dir2}"
     paths = ruby_exe("puts $LOAD_PATH").lines.map(&:chomp)
-    paths.should include(dir1)
-    paths.should include(dir2)
+    paths.should.include?(dir1)
+    paths.should.include?(dir2)
     paths.index(dir1).should < paths.index(dir2)
   end
 
@@ -46,8 +46,8 @@ describe "The RUBYLIB environment variable" do
     rubylib_dir = tmp("rubylib_include")
     ENV["RUBYLIB"] = @pre + rubylib_dir
     paths = ruby_exe("puts $LOAD_PATH", options: "-I #{dash_i_dir}").lines.map(&:chomp)
-    paths.should include(dash_i_dir)
-    paths.should include(rubylib_dir)
+    paths.should.include?(dash_i_dir)
+    paths.should.include?(rubylib_dir)
     paths.index(dash_i_dir).should < paths.index(rubylib_dir)
   end
 
@@ -56,14 +56,14 @@ describe "The RUBYLIB environment variable" do
     rubylib_dir = tmp("rubylib_include")
     ENV["RUBYLIB"] = @pre + rubylib_dir
     paths = ruby_exe("puts $LOAD_PATH", env: { "RUBYOPT" => "-I#{rubyopt_dir}" }).lines.map(&:chomp)
-    paths.should include(rubyopt_dir)
-    paths.should include(rubylib_dir)
+    paths.should.include?(rubyopt_dir)
+    paths.should.include?(rubylib_dir)
     paths.index(rubyopt_dir).should < paths.index(rubylib_dir)
   end
 
   it "keeps spaces in the value" do
     ENV["RUBYLIB"] = @pre + " rubylib/incl "
     out = ruby_exe("puts $LOAD_PATH")
-    out.should include(" rubylib/incl ")
+    out.should.include?(" rubylib/incl ")
   end
 end
diff --git a/spec/ruby/command_line/rubyopt_spec.rb b/spec/ruby/command_line/rubyopt_spec.rb
index 2db42f77ef..eb297cd6fe 100644
--- a/spec/ruby/command_line/rubyopt_spec.rb
+++ b/spec/ruby/command_line/rubyopt_spec.rb
@@ -11,52 +11,70 @@ describe "Processing RUBYOPT" do
 
   it "adds the -I path to $LOAD_PATH" do
     ENV["RUBYOPT"] = "-Ioptrubyspecincl"
-    result = ruby_exe("puts $LOAD_PATH.grep(/byspecin/)", escape: true)
+    result = ruby_exe("puts $LOAD_PATH.grep(/byspecin/)")
     result.chomp[-15..-1].should == "optrubyspecincl"
   end
 
   it "sets $DEBUG to true for '-d'" do
     ENV["RUBYOPT"] = '-d'
     command = %[puts "value of $DEBUG is \#{$DEBUG}"]
-    result = ruby_exe(command, escape: true, args: "2>&1")
+    result = ruby_exe(command, args: "2>&1")
     result.should =~ /value of \$DEBUG is true/
   end
 
-  guard -> { not CROSS_COMPILING } do
+  guard -> { RbConfig::CONFIG["CROSS_COMPILING"] != "yes" } do
     it "prints the version number for '-v'" do
       ENV["RUBYOPT"] = '-v'
-      ruby_exe("")[/\A.*/].should == RUBY_DESCRIPTION
+      ruby_exe("")[/\A.*/].gsub(/\s\+(YJIT( \w+)?|ZJIT( \w+)?|PRISM|GC(\[\w+\])?)(?=\s)/, "").should == RUBY_DESCRIPTION.gsub(/\s\+(YJIT( \w+)?|ZJIT( \w+)?|PRISM|GC(\[\w+\])?)(?=\s)/, "")
     end
 
     it "ignores whitespace around the option" do
       ENV["RUBYOPT"] = ' -v '
-      ruby_exe("")[/\A.*/].should == RUBY_DESCRIPTION
+      ruby_exe("")[/\A.*/].gsub(/\s\+(YJIT( \w+)?|ZJIT( \w+)?|PRISM|GC(\[\w+\])?)(?=\s)/, "").should == RUBY_DESCRIPTION.gsub(/\s\+(YJIT( \w+)?|ZJIT( \w+)?|PRISM|GC(\[\w+\])?)(?=\s)/, "")
     end
   end
 
   it "sets $VERBOSE to true for '-w'" do
     ENV["RUBYOPT"] = '-w'
-    ruby_exe("p $VERBOSE", escape: true).chomp.should == "true"
+    ruby_exe("p $VERBOSE").chomp.should == "true"
   end
 
   it "sets $VERBOSE to true for '-W'" do
     ENV["RUBYOPT"] = '-W'
-    ruby_exe("p $VERBOSE", escape: true).chomp.should == "true"
+    ruby_exe("p $VERBOSE").chomp.should == "true"
   end
 
   it "sets $VERBOSE to nil for '-W0'" do
     ENV["RUBYOPT"] = '-W0'
-    ruby_exe("p $VERBOSE", escape: true).chomp.should == "nil"
+    ruby_exe("p $VERBOSE").chomp.should == "nil"
   end
 
   it "sets $VERBOSE to false for '-W1'" do
     ENV["RUBYOPT"] = '-W1'
-    ruby_exe("p $VERBOSE", escape: true).chomp.should == "false"
+    ruby_exe("p $VERBOSE").chomp.should == "false"
   end
 
   it "sets $VERBOSE to true for '-W2'" do
     ENV["RUBYOPT"] = '-W2'
-    ruby_exe("p $VERBOSE", escape: true).chomp.should == "true"
+    ruby_exe("p $VERBOSE").chomp.should == "true"
+  end
+
+  it "suppresses deprecation warnings for '-W:no-deprecated'" do
+    ENV["RUBYOPT"] = '-W:no-deprecated'
+    result = ruby_exe('$; = ""', args: '2>&1')
+    result.should == ""
+  end
+
+  it "suppresses experimental warnings for '-W:no-experimental'" do
+    ENV["RUBYOPT"] = '-W:no-experimental'
+    result = ruby_exe('case 0; in a; end', args: '2>&1')
+    result.should == ""
+  end
+
+  it "suppresses deprecation and experimental warnings for '-W:no-deprecated -W:no-experimental'" do
+    ENV["RUBYOPT"] = '-W:no-deprecated -W:no-experimental'
+    result = ruby_exe('case ($; = ""); in a; end', args: '2>&1')
+    result.should == ""
   end
 
   it "requires the file for '-r'" do
@@ -67,101 +85,101 @@ describe "Processing RUBYOPT" do
 
   it "raises a RuntimeError for '-a'" do
     ENV["RUBYOPT"] = '-a'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-p'" do
     ENV["RUBYOPT"] = '-p'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-n'" do
     ENV["RUBYOPT"] = '-n'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-y'" do
     ENV["RUBYOPT"] = '-y'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-c'" do
     ENV["RUBYOPT"] = '-c'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-s'" do
     ENV["RUBYOPT"] = '-s'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-h'" do
     ENV["RUBYOPT"] = '-h'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '--help'" do
     ENV["RUBYOPT"] = '--help'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-l'" do
     ENV["RUBYOPT"] = '-l'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-S'" do
     ENV["RUBYOPT"] = '-S irb'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-e'" do
     ENV["RUBYOPT"] = '-e0'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-i'" do
     ENV["RUBYOPT"] = '-i.bak'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-x'" do
     ENV["RUBYOPT"] = '-x'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-C'" do
     ENV["RUBYOPT"] = '-C'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-X'" do
     ENV["RUBYOPT"] = '-X.'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-F'" do
     ENV["RUBYOPT"] = '-F'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '-0'" do
     ENV["RUBYOPT"] = '-0'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '--copyright'" do
     ENV["RUBYOPT"] = '--copyright'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '--version'" do
     ENV["RUBYOPT"] = '--version'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 
   it "raises a RuntimeError for '--yydebug'" do
     ENV["RUBYOPT"] = '--yydebug'
-    ruby_exe("", args: '2>&1').should =~ /RuntimeError/
+    ruby_exe("", args: '2>&1', exit_status: 1).should =~ /RuntimeError/
   end
 end
diff --git a/spec/ruby/command_line/syntax_error_spec.rb b/spec/ruby/command_line/syntax_error_spec.rb
index f61cfe928d..88864c048e 100644
--- a/spec/ruby/command_line/syntax_error_spec.rb
+++ b/spec/ruby/command_line/syntax_error_spec.rb
@@ -2,12 +2,12 @@ require_relative '../spec_helper'
 
 describe "The interpreter" do
   it "prints an error when given a file with invalid syntax" do
-    out = ruby_exe(fixture(__FILE__, "bad_syntax.rb"), args: "2>&1")
-    out.should include "syntax error"
+    out = ruby_exe(fixture(__FILE__, "bad_syntax.rb"), args: "2>&1", exit_status: 1)
+    out.should.include?("SyntaxError")
   end
 
   it "prints an error when given code via -e with invalid syntax" do
-    out = ruby_exe(nil, args: "-e 'a{' 2>&1")
-    out.should include "syntax error"
+    out = ruby_exe(nil, args: "-e 'a{' 2>&1", exit_status: 1)
+    out.should.include?("SyntaxError")
   end
 end
diff --git a/spec/ruby/core/argf/argf_spec.rb b/spec/ruby/core/argf/argf_spec.rb
index af67170b98..f9468539bb 100644
--- a/spec/ruby/core/argf/argf_spec.rb
+++ b/spec/ruby/core/argf/argf_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "ARGF" do
   it "is extended by the Enumerable module" do
-    ARGF.should be_kind_of(Enumerable)
+    ARGF.should.is_a?(Enumerable)
   end
 
   it "is an instance of ARGF.class" do
-    ARGF.should be_an_instance_of(ARGF.class)
+    ARGF.should.instance_of?(ARGF.class)
   end
 end
diff --git a/spec/ruby/core/argf/argv_spec.rb b/spec/ruby/core/argf/argv_spec.rb
index eab03c450f..77dfe78c21 100644
--- a/spec/ruby/core/argf/argv_spec.rb
+++ b/spec/ruby/core/argf/argv_spec.rb
@@ -7,7 +7,7 @@ describe "ARGF.argv" do
   end
 
   it "returns ARGV for the initial ARGF" do
-    ARGF.argv.should equal ARGV
+    ARGF.argv.should.equal? ARGV
   end
 
   it "returns the remaining arguments to treat" do
diff --git a/spec/ruby/core/argf/binmode_spec.rb b/spec/ruby/core/argf/binmode_spec.rb
index c2dd578d95..5288e3199d 100644
--- a/spec/ruby/core/argf/binmode_spec.rb
+++ b/spec/ruby/core/argf/binmode_spec.rb
@@ -9,7 +9,7 @@ describe "ARGF.binmode" do
 
   it "returns self" do
     argf [@bin_file] do
-      @argf.binmode.should equal @argf
+      @argf.binmode.should.equal? @argf
     end
   end
 
@@ -22,7 +22,7 @@ describe "ARGF.binmode" do
       end
     end
 
-    it "puts alls subsequent stream reading through ARGF into binmode" do
+    it "puts all subsequent streams reading through ARGF into binmode" do
       argf [@bin_file, @bin_file] do
         @argf.binmode
         @argf.gets.should == "test\r\n"
@@ -34,7 +34,7 @@ describe "ARGF.binmode" do
   it "sets the file's encoding to BINARY" do
     argf [@bin_file, @file1] do
       @argf.binmode
-      @argf.binmode?.should == true
+      @argf.should.binmode?
       @argf.gets.encoding.should == Encoding::BINARY
       @argf.skip
       @argf.read.encoding.should == Encoding::BINARY
diff --git a/spec/ruby/core/argf/bytes_spec.rb b/spec/ruby/core/argf/bytes_spec.rb
deleted file mode 100644
index 71d07fabcb..0000000000
--- a/spec/ruby/core/argf/bytes_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/each_byte'
-
-describe "ARGF.bytes" do
-  it_behaves_like :argf_each_byte, :bytes
-end
diff --git a/spec/ruby/core/argf/chars_spec.rb b/spec/ruby/core/argf/chars_spec.rb
deleted file mode 100644
index ee79ea763b..0000000000
--- a/spec/ruby/core/argf/chars_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/each_char'
-
-describe "ARGF.chars" do
-  it_behaves_like :argf_each_char, :chars
-end
diff --git a/spec/ruby/core/argf/close_spec.rb b/spec/ruby/core/argf/close_spec.rb
index d4d6a51e72..8ca7d71dc2 100644
--- a/spec/ruby/core/argf/close_spec.rb
+++ b/spec/ruby/core/argf/close_spec.rb
@@ -10,20 +10,20 @@ describe "ARGF.close" do
     argf [@file1_name, @file2_name] do
       io = @argf.to_io
       @argf.close
-      io.closed?.should be_true
+      io.closed?.should == true
     end
   end
 
   it "returns self" do
     argf [@file1_name, @file2_name] do
-      @argf.close.should equal(@argf)
+      @argf.close.should.equal?(@argf)
     end
   end
 
   it "doesn't raise an IOError if called on a closed stream" do
     argf [@file1_name] do
-      -> { @argf.close }.should_not raise_error
-      -> { @argf.close }.should_not raise_error
+      -> { @argf.close }.should_not.raise
+      -> { @argf.close }.should_not.raise
     end
   end
 end
diff --git a/spec/ruby/core/argf/closed_spec.rb b/spec/ruby/core/argf/closed_spec.rb
index e2dd6134e5..769381e8c3 100644
--- a/spec/ruby/core/argf/closed_spec.rb
+++ b/spec/ruby/core/argf/closed_spec.rb
@@ -11,7 +11,7 @@ describe "ARGF.closed?" do
       stream = @argf.to_io
       stream.close
 
-      @argf.closed?.should be_true
+      @argf.closed?.should == true
       stream.reopen(@argf.filename, 'r')
     end
   end
diff --git a/spec/ruby/core/argf/codepoints_spec.rb b/spec/ruby/core/argf/codepoints_spec.rb
deleted file mode 100644
index 7aa8a761fe..0000000000
--- a/spec/ruby/core/argf/codepoints_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/each_codepoint'
-
-describe "ARGF.codepoints" do
-  it_behaves_like :argf_each_codepoint, :codepoints
-end
diff --git a/spec/ruby/core/argf/each_byte_spec.rb b/spec/ruby/core/argf/each_byte_spec.rb
index c5cce9f250..d9e4e7fe5b 100644
--- a/spec/ruby/core/argf/each_byte_spec.rb
+++ b/spec/ruby/core/argf/each_byte_spec.rb
@@ -1,6 +1,60 @@
 require_relative '../../spec_helper'
-require_relative 'shared/each_byte'
 
 describe "ARGF.each_byte" do
-  it_behaves_like :argf_each_byte, :each_byte
+  before :each do
+    @file1_name = fixture __FILE__, "file1.txt"
+    @file2_name = fixture __FILE__, "file2.txt"
+
+    @bytes = []
+    File.read(@file1_name).each_byte { |b| @bytes << b }
+    File.read(@file2_name).each_byte { |b| @bytes << b }
+  end
+
+  it "yields each byte of all streams to the passed block" do
+    argf [@file1_name, @file2_name] do
+      bytes = []
+      @argf.each_byte { |b| bytes << b }
+      bytes.should == @bytes
+    end
+  end
+
+  it "returns self when passed a block" do
+    argf [@file1_name, @file2_name] do
+      @argf.each_byte {}.should.equal?(@argf)
+    end
+  end
+
+  it "returns an Enumerator when passed no block" do
+    argf [@file1_name, @file2_name] do
+      enum = @argf.each_byte
+      enum.should.instance_of?(Enumerator)
+
+      bytes = []
+      enum.each { |b| bytes << b }
+      bytes.should == @bytes
+    end
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      argf [@file1_name, @file2_name] do
+        enum = @argf.each_byte
+        enum.should.instance_of?(Enumerator)
+
+        bytes = []
+        enum.each { |b| bytes << b }
+        bytes.should == @bytes
+      end
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          argf [@file1_name, @file2_name] do
+            @argf.each_byte.size.should == nil
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/each_char_spec.rb b/spec/ruby/core/argf/each_char_spec.rb
index 724e5e6e3e..62d19b6574 100644
--- a/spec/ruby/core/argf/each_char_spec.rb
+++ b/spec/ruby/core/argf/each_char_spec.rb
@@ -1,6 +1,60 @@
 require_relative '../../spec_helper'
-require_relative 'shared/each_char'
 
 describe "ARGF.each_char" do
-  it_behaves_like :argf_each_char, :each_char
+  before :each do
+    @file1_name = fixture __FILE__, "file1.txt"
+    @file2_name = fixture __FILE__, "file2.txt"
+
+    @chars = []
+    File.read(@file1_name).each_char { |c| @chars << c }
+    File.read(@file2_name).each_char { |c| @chars << c }
+  end
+
+  it "yields each char of all streams to the passed block" do
+    argf [@file1_name, @file2_name] do
+      chars = []
+      @argf.each_char { |c| chars << c }
+      chars.should == @chars
+    end
+  end
+
+  it "returns self when passed a block" do
+    argf [@file1_name, @file2_name] do
+      @argf.each_char {}.should.equal?(@argf)
+    end
+  end
+
+  it "returns an Enumerator when passed no block" do
+    argf [@file1_name, @file2_name] do
+      enum = @argf.each_char
+      enum.should.instance_of?(Enumerator)
+
+      chars = []
+      enum.each { |c| chars << c }
+      chars.should == @chars
+    end
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      argf [@file1_name, @file2_name] do
+        enum = @argf.each_char
+        enum.should.instance_of?(Enumerator)
+
+        chars = []
+        enum.each { |c| chars << c }
+        chars.should == @chars
+      end
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          argf [@file1_name, @file2_name] do
+            @argf.each_char.size.should == nil
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/each_codepoint_spec.rb b/spec/ruby/core/argf/each_codepoint_spec.rb
index 0bf8bf9764..ad55785cba 100644
--- a/spec/ruby/core/argf/each_codepoint_spec.rb
+++ b/spec/ruby/core/argf/each_codepoint_spec.rb
@@ -1,6 +1,60 @@
 require_relative '../../spec_helper'
-require_relative 'shared/each_codepoint'
 
 describe "ARGF.each_codepoint" do
-  it_behaves_like :argf_each_codepoint, :each_codepoint
+  before :each do
+    file1_name = fixture __FILE__, "file1.txt"
+    file2_name = fixture __FILE__, "file2.txt"
+    @filenames = [file1_name, file2_name]
+
+    @codepoints = File.read(file1_name).codepoints
+    @codepoints.concat File.read(file2_name).codepoints
+  end
+
+  it "is a public method" do
+    argf @filenames do
+      @argf.public_methods(false).should.include?(:each_codepoint)
+    end
+  end
+
+  it "does not require arguments" do
+    argf @filenames do
+      @argf.method(:each_codepoint).arity.should == 0
+    end
+  end
+
+  it "returns self when passed a block" do
+    argf @filenames do
+      @argf.each_codepoint {}.should.equal?(@argf)
+    end
+  end
+
+  it "returns an Enumerator when passed no block" do
+    argf @filenames do
+      @argf.each_codepoint.should.instance_of?(Enumerator)
+    end
+  end
+
+  it "yields each codepoint of all streams" do
+    argf @filenames do
+      @argf.each_codepoint.to_a.should == @codepoints
+    end
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      argf @filenames do
+        @argf.each_codepoint.should.instance_of?(Enumerator)
+      end
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          argf @filenames do
+            @argf.each_codepoint.size.should == nil
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/each_line_spec.rb b/spec/ruby/core/argf/each_line_spec.rb
index 52a7e5c411..fc4d6433b8 100644
--- a/spec/ruby/core/argf/each_line_spec.rb
+++ b/spec/ruby/core/argf/each_line_spec.rb
@@ -1,6 +1,64 @@
 require_relative '../../spec_helper'
-require_relative 'shared/each_line'
 
 describe "ARGF.each_line" do
-  it_behaves_like :argf_each_line, :each_line
+  before :each do
+    @file1_name = fixture __FILE__, "file1.txt"
+    @file2_name = fixture __FILE__, "file2.txt"
+
+    @lines  = File.readlines @file1_name
+    @lines += File.readlines @file2_name
+  end
+
+  it "is a public method" do
+    argf [@file1_name, @file2_name] do
+      @argf.public_methods(false).should.include?(:each_line)
+    end
+  end
+
+  it "requires multiple arguments" do
+    argf [@file1_name, @file2_name] do
+      @argf.method(:each_line).arity.should < 0
+    end
+  end
+
+  it "reads each line of files" do
+    argf [@file1_name, @file2_name] do
+      lines = []
+      @argf.each_line { |b| lines << b }
+      lines.should == @lines
+    end
+  end
+
+  it "returns self when passed a block" do
+    argf [@file1_name, @file2_name] do
+      @argf.each_line {}.should.equal?(@argf)
+    end
+  end
+
+  describe "with a separator" do
+    it "yields each separated section of all streams" do
+      argf [@file1_name, @file2_name] do
+        @argf.send(:each_line, '.').to_a.should ==
+          (File.readlines(@file1_name, '.') + File.readlines(@file2_name, '.'))
+      end
+    end
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      argf [@file1_name, @file2_name] do
+        @argf.each_line.should.instance_of?(Enumerator)
+      end
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          argf [@file1_name, @file2_name] do
+            @argf.each_line.size.should == nil
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/each_spec.rb b/spec/ruby/core/argf/each_spec.rb
index 5742ba43bd..25f60b31d2 100644
--- a/spec/ruby/core/argf/each_spec.rb
+++ b/spec/ruby/core/argf/each_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/each_line'
 
 describe "ARGF.each" do
-  it_behaves_like :argf_each_line, :each
+  it "is an alias of ARGF.each_line" do
+    ARGF.method(:each).should == ARGF.method(:each_line)
+  end
 end
diff --git a/spec/ruby/core/argf/eof_spec.rb b/spec/ruby/core/argf/eof_spec.rb
index 518f6e566e..940d104d69 100644
--- a/spec/ruby/core/argf/eof_spec.rb
+++ b/spec/ruby/core/argf/eof_spec.rb
@@ -1,10 +1,32 @@
 require_relative '../../spec_helper'
-require_relative 'shared/eof'
 
 describe "ARGF.eof" do
-  it_behaves_like :argf_eof, :eof
+  it "is an alias of ARGF.eof?" do
+    ARGF.method(:eof).should == ARGF.method(:eof?)
+  end
 end
 
 describe "ARGF.eof?" do
-  it_behaves_like :argf_eof, :eof?
+  before :each do
+    @file1 = fixture __FILE__, "file1.txt"
+    @file2 = fixture __FILE__, "file2.txt"
+  end
+
+  # NOTE: this test assumes that fixtures files have two lines each
+  it "returns true when reaching the end of a file" do
+    argf [@file1, @file2] do
+      result = []
+      while @argf.gets
+        result << @argf.eof?
+      end
+      result.should == [false, true, false, true]
+    end
+  end
+
+  it "raises IOError when called on a closed stream" do
+    argf [@file1] do
+      @argf.read
+      -> { @argf.eof? }.should.raise(IOError)
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/filename_spec.rb b/spec/ruby/core/argf/filename_spec.rb
index 7c0446269d..f4b6e922c6 100644
--- a/spec/ruby/core/argf/filename_spec.rb
+++ b/spec/ruby/core/argf/filename_spec.rb
@@ -1,6 +1,30 @@
 require_relative '../../spec_helper'
-require_relative 'shared/filename'
 
 describe "ARGF.filename" do
-  it_behaves_like :argf_filename, :filename
+  before :each do
+    @file1 = fixture __FILE__, "file1.txt"
+    @file2 = fixture __FILE__, "file2.txt"
+  end
+
+  # NOTE: this test assumes that fixtures files have two lines each
+  it "returns the current file name on each file" do
+    argf [@file1, @file2] do
+      result = []
+      # returns first current file even when not yet open
+      result << @argf.filename
+      result << @argf.filename while @argf.gets
+      # returns last current file even when closed
+      result << @argf.filename
+
+      result.map! { |f| File.expand_path(f) }
+      result.should == [@file1, @file1, @file1, @file2, @file2, @file2]
+    end
+  end
+
+  # NOTE: this test assumes that fixtures files have two lines each
+  it "sets the $FILENAME global variable with the current file name on each file" do
+    script = fixture __FILE__, "filename.rb"
+    out = ruby_exe(script, args: [@file1, @file2])
+    out.should == "#{@file1}\n#{@file1}\n#{@file2}\n#{@file2}\n#{@file2}\n"
+  end
 end
diff --git a/spec/ruby/core/argf/fileno_spec.rb b/spec/ruby/core/argf/fileno_spec.rb
index 29d50c3582..99245f043c 100644
--- a/spec/ruby/core/argf/fileno_spec.rb
+++ b/spec/ruby/core/argf/fileno_spec.rb
@@ -1,6 +1,26 @@
 require_relative '../../spec_helper'
-require_relative 'shared/fileno'
 
 describe "ARGF.fileno" do
-  it_behaves_like :argf_fileno, :fileno
+  before :each do
+    @file1 = fixture __FILE__, "file1.txt"
+    @file2 = fixture __FILE__, "file2.txt"
+  end
+
+  # NOTE: this test assumes that fixtures files have two lines each
+  it "returns the current file number on each file" do
+    argf [@file1, @file2] do
+      result = []
+      # returns first current file even when not yet open
+      result << @argf.fileno while @argf.gets
+      # returns last current file even when closed
+      result.map { |d| d.class }.should == [Integer, Integer, Integer, Integer]
+    end
+  end
+
+  it "raises an ArgumentError when called on a closed stream" do
+    argf [@file1] do
+      @argf.read
+      -> { @argf.fileno }.should.raise(ArgumentError)
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/inspect_spec.rb b/spec/ruby/core/argf/inspect_spec.rb
new file mode 100644
index 0000000000..df0e3ba8dc
--- /dev/null
+++ b/spec/ruby/core/argf/inspect_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../spec_helper'
+
+describe "ARGF.inspect" do
+  it "is an alias of ARGF.to_s" do
+    ARGF.method(:inspect).should == ARGF.method(:to_s)
+  end
+end
diff --git a/spec/ruby/core/argf/lines_spec.rb b/spec/ruby/core/argf/lines_spec.rb
deleted file mode 100644
index 6ca6ff1256..0000000000
--- a/spec/ruby/core/argf/lines_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/each_line'
-
-describe "ARGF.lines" do
-  it_behaves_like :argf_each_line, :lines
-end
diff --git a/spec/ruby/core/argf/path_spec.rb b/spec/ruby/core/argf/path_spec.rb
index 7120f7d0e3..2f7b91999f 100644
--- a/spec/ruby/core/argf/path_spec.rb
+++ b/spec/ruby/core/argf/path_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/filename'
 
 describe "ARGF.path" do
-  it_behaves_like :argf_filename, :path
+  it "is an alias of ARGF.filename" do
+    ARGF.method(:path).should == ARGF.method(:filename)
+  end
 end
diff --git a/spec/ruby/core/argf/pos_spec.rb b/spec/ruby/core/argf/pos_spec.rb
index fb3f25b945..1ff16e4f17 100644
--- a/spec/ruby/core/argf/pos_spec.rb
+++ b/spec/ruby/core/argf/pos_spec.rb
@@ -1,8 +1,35 @@
 require_relative '../../spec_helper'
-require_relative 'shared/pos'
 
 describe "ARGF.pos" do
-  it_behaves_like :argf_pos, :pos
+  before :each do
+    @file1 = fixture __FILE__, "file1.txt"
+    @file2 = fixture __FILE__, "file2.txt"
+  end
+
+  it "gives the correct position for each read operation" do
+    argf [@file1, @file2] do
+      size1 = File.size(@file1)
+      size2 = File.size(@file2)
+
+      @argf.read(2)
+      @argf.pos.should == 2
+      @argf.read(size1-2)
+      @argf.pos.should == size1
+      @argf.read(6)
+      @argf.pos.should == 6
+      @argf.rewind
+      @argf.pos.should == 0
+      @argf.read(size2)
+      @argf.pos.should == size2
+    end
+  end
+
+  it "raises an ArgumentError when called on a closed stream" do
+    argf [@file1] do
+      @argf.read
+      -> { @argf.pos }.should.raise(ArgumentError)
+    end
+  end
 end
 
 describe "ARGF.pos=" do
diff --git a/spec/ruby/core/argf/read_nonblock_spec.rb b/spec/ruby/core/argf/read_nonblock_spec.rb
index 804a459a62..5c6bd52d80 100644
--- a/spec/ruby/core/argf/read_nonblock_spec.rb
+++ b/spec/ruby/core/argf/read_nonblock_spec.rb
@@ -66,7 +66,7 @@ platform_is_not :windows do
         argf ['-'] do
           -> {
             @argf.read_nonblock(4)
-          }.should raise_error(IO::EAGAINWaitReadable)
+          }.should.raise(IO::EAGAINWaitReadable)
         end
       end
 
diff --git a/spec/ruby/core/argf/readchar_spec.rb b/spec/ruby/core/argf/readchar_spec.rb
index 4eca2efcf7..63632721ec 100644
--- a/spec/ruby/core/argf/readchar_spec.rb
+++ b/spec/ruby/core/argf/readchar_spec.rb
@@ -13,7 +13,7 @@ describe "ARGF.readchar" do
 
   it "raises EOFError when end of stream reached" do
     argf [@file1, @file2] do
-      -> { while @argf.readchar; end }.should raise_error(EOFError)
+      -> { while @argf.readchar; end }.should.raise(EOFError)
     end
   end
 end
diff --git a/spec/ruby/core/argf/readline_spec.rb b/spec/ruby/core/argf/readline_spec.rb
index db53c499e9..8c23549b1b 100644
--- a/spec/ruby/core/argf/readline_spec.rb
+++ b/spec/ruby/core/argf/readline_spec.rb
@@ -17,7 +17,7 @@ describe "ARGF.readline" do
 
   it "raises an EOFError when reaching end of files" do
     argf [@file1, @file2] do
-      -> { while @argf.readline; end }.should raise_error(EOFError)
+      -> { while @argf.readline; end }.should.raise(EOFError)
     end
   end
 end
diff --git a/spec/ruby/core/argf/readlines_spec.rb b/spec/ruby/core/argf/readlines_spec.rb
index 30be936dab..156bb6a33f 100644
--- a/spec/ruby/core/argf/readlines_spec.rb
+++ b/spec/ruby/core/argf/readlines_spec.rb
@@ -1,6 +1,24 @@
 require_relative '../../spec_helper'
-require_relative 'shared/readlines'
 
 describe "ARGF.readlines" do
-  it_behaves_like :argf_readlines, :readlines
+  before :each do
+    @file1 = fixture __FILE__, "file1.txt"
+    @file2 = fixture __FILE__, "file2.txt"
+
+    @lines  = File.readlines(@file1)
+    @lines += File.readlines(@file2)
+  end
+
+  it "reads all lines of all files" do
+    argf [@file1, @file2] do
+      @argf.readlines.should == @lines
+    end
+  end
+
+  it "returns an empty Array when end of stream reached" do
+    argf [@file1, @file2] do
+      @argf.read
+      @argf.readlines.should == []
+    end
+  end
 end
diff --git a/spec/ruby/core/argf/readpartial_spec.rb b/spec/ruby/core/argf/readpartial_spec.rb
index 5e284b3423..9f04e72cc2 100644
--- a/spec/ruby/core/argf/readpartial_spec.rb
+++ b/spec/ruby/core/argf/readpartial_spec.rb
@@ -16,7 +16,7 @@ describe "ARGF.readpartial" do
 
   it "raises an ArgumentError if called without a maximum read length" do
     argf [@file1_name] do
-      -> { @argf.readpartial }.should raise_error(ArgumentError)
+      -> { @argf.readpartial }.should.raise(ArgumentError)
     end
   end
 
@@ -29,7 +29,7 @@ describe "ARGF.readpartial" do
 
   it "clears output buffer even if EOFError is raised because @argf is at end" do
     begin
-      output = "to be cleared"
+      output = +"to be cleared"
 
       argf [@file1_name] do
         @argf.read
@@ -59,8 +59,8 @@ describe "ARGF.readpartial" do
       @argf.readpartial(@file1.size)
       @argf.readpartial(1)
       @argf.readpartial(@file2.size)
-      -> { @argf.readpartial(1) }.should raise_error(EOFError)
-      -> { @argf.readpartial(1) }.should raise_error(EOFError)
+      -> { @argf.readpartial(1) }.should.raise(EOFError)
+      -> { @argf.readpartial(1) }.should.raise(EOFError)
     end
   end
 
@@ -69,7 +69,7 @@ describe "ARGF.readpartial" do
       print ARGF.readpartial(#{@stdin.size})
       ARGF.readpartial(1) rescue print $!.class
     STR
-    stdin = ruby_exe(ruby_str, args: "< #{@stdin_name}", escape: true)
+    stdin = ruby_exe(ruby_str, args: "< #{@stdin_name}")
     stdin.should == @stdin + "EOFError"
   end
 end
diff --git a/spec/ruby/core/argf/rewind_spec.rb b/spec/ruby/core/argf/rewind_spec.rb
index b29f0b75b7..9255f790fe 100644
--- a/spec/ruby/core/argf/rewind_spec.rb
+++ b/spec/ruby/core/argf/rewind_spec.rb
@@ -33,7 +33,7 @@ describe "ARGF.rewind" do
   it "raises an ArgumentError when end of stream reached" do
     argf [@file1_name, @file2_name] do
       @argf.read
-      -> { @argf.rewind }.should raise_error(ArgumentError)
+      -> { @argf.rewind }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/argf/seek_spec.rb b/spec/ruby/core/argf/seek_spec.rb
index 2b73bd46fb..c1ea1ea438 100644
--- a/spec/ruby/core/argf/seek_spec.rb
+++ b/spec/ruby/core/argf/seek_spec.rb
@@ -57,7 +57,7 @@ describe "ARGF.seek" do
 
   it "takes at least one argument (offset)" do
     argf [@file1_name] do
-      -> { @argf.seek }.should raise_error(ArgumentError)
+      -> { @argf.seek }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/argf/shared/each_byte.rb b/spec/ruby/core/argf/shared/each_byte.rb
deleted file mode 100644
index 6b1dc1dae2..0000000000
--- a/spec/ruby/core/argf/shared/each_byte.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-describe :argf_each_byte, shared: true do
-  before :each do
-    @file1_name = fixture __FILE__, "file1.txt"
-    @file2_name = fixture __FILE__, "file2.txt"
-
-    @bytes = []
-    File.read(@file1_name).each_byte { |b| @bytes << b }
-    File.read(@file2_name).each_byte { |b| @bytes << b }
-  end
-
-  it "yields each byte of all streams to the passed block" do
-    argf [@file1_name, @file2_name] do
-      bytes = []
-      @argf.send(@method) { |b| bytes << b }
-      bytes.should == @bytes
-    end
-  end
-
-  it "returns self when passed a block" do
-    argf [@file1_name, @file2_name] do
-      @argf.send(@method) {}.should equal(@argf)
-    end
-  end
-
-  it "returns an Enumerator when passed no block" do
-    argf [@file1_name, @file2_name] do
-      enum = @argf.send(@method)
-      enum.should be_an_instance_of(Enumerator)
-
-      bytes = []
-      enum.each { |b| bytes << b }
-      bytes.should == @bytes
-    end
-  end
-
-  describe "when no block is given" do
-    it "returns an Enumerator" do
-      argf [@file1_name, @file2_name] do
-        enum = @argf.send(@method)
-        enum.should be_an_instance_of(Enumerator)
-
-        bytes = []
-        enum.each { |b| bytes << b }
-        bytes.should == @bytes
-      end
-    end
-
-    describe "returned Enumerator" do
-      describe "size" do
-        it "should return nil" do
-          argf [@file1_name, @file2_name] do
-            @argf.send(@method).size.should == nil
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/each_char.rb b/spec/ruby/core/argf/shared/each_char.rb
deleted file mode 100644
index 9e333ecc5b..0000000000
--- a/spec/ruby/core/argf/shared/each_char.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-describe :argf_each_char, shared: true do
-  before :each do
-    @file1_name = fixture __FILE__, "file1.txt"
-    @file2_name = fixture __FILE__, "file2.txt"
-
-    @chars = []
-    File.read(@file1_name).each_char { |c| @chars << c }
-    File.read(@file2_name).each_char { |c| @chars << c }
-  end
-
-  it "yields each char of all streams to the passed block" do
-    argf [@file1_name, @file2_name] do
-      chars = []
-      @argf.send(@method) { |c| chars << c }
-      chars.should == @chars
-    end
-  end
-
-  it "returns self when passed a block" do
-    argf [@file1_name, @file2_name] do
-      @argf.send(@method) {}.should equal(@argf)
-    end
-  end
-
-  it "returns an Enumerator when passed no block" do
-    argf [@file1_name, @file2_name] do
-      enum = @argf.send(@method)
-      enum.should be_an_instance_of(Enumerator)
-
-      chars = []
-      enum.each { |c| chars << c }
-      chars.should == @chars
-    end
-  end
-
-  describe "when no block is given" do
-    it "returns an Enumerator" do
-      argf [@file1_name, @file2_name] do
-        enum = @argf.send(@method)
-        enum.should be_an_instance_of(Enumerator)
-
-        chars = []
-        enum.each { |c| chars << c }
-        chars.should == @chars
-      end
-    end
-
-    describe "returned Enumerator" do
-      describe "size" do
-        it "should return nil" do
-          argf [@file1_name, @file2_name] do
-            @argf.send(@method).size.should == nil
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/each_codepoint.rb b/spec/ruby/core/argf/shared/each_codepoint.rb
deleted file mode 100644
index e2a2dfff46..0000000000
--- a/spec/ruby/core/argf/shared/each_codepoint.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-describe :argf_each_codepoint, shared: true do
-  before :each do
-    file1_name = fixture __FILE__, "file1.txt"
-    file2_name = fixture __FILE__, "file2.txt"
-    @filenames = [file1_name, file2_name]
-
-    @codepoints = File.read(file1_name).codepoints
-    @codepoints.concat File.read(file2_name).codepoints
-  end
-
-  it "is a public method" do
-    argf @filenames do
-      @argf.public_methods(false).should include(@method)
-    end
-  end
-
-  it "does not require arguments" do
-    argf @filenames do
-      @argf.method(@method).arity.should == 0
-    end
-  end
-
-  it "returns self when passed a block" do
-    argf @filenames do
-      @argf.send(@method) {}.should equal(@argf)
-    end
-  end
-
-  it "returns an Enumerator when passed no block" do
-    argf @filenames do
-      @argf.send(@method).should be_an_instance_of(Enumerator)
-    end
-  end
-
-  it "yields each codepoint of all streams" do
-    argf @filenames do
-      @argf.send(@method).to_a.should == @codepoints
-    end
-  end
-
-  describe "when no block is given" do
-    it "returns an Enumerator" do
-      argf @filenames do
-        @argf.send(@method).should be_an_instance_of(Enumerator)
-      end
-    end
-
-    describe "returned Enumerator" do
-      describe "size" do
-        it "should return nil" do
-          argf @filenames do
-            @argf.send(@method).size.should == nil
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/each_line.rb b/spec/ruby/core/argf/shared/each_line.rb
deleted file mode 100644
index c0ef77dc54..0000000000
--- a/spec/ruby/core/argf/shared/each_line.rb
+++ /dev/null
@@ -1,62 +0,0 @@
-describe :argf_each_line, shared: true do
-  before :each do
-    @file1_name = fixture __FILE__, "file1.txt"
-    @file2_name = fixture __FILE__, "file2.txt"
-
-    @lines  = File.readlines @file1_name
-    @lines += File.readlines @file2_name
-  end
-
-  it "is a public method" do
-    argf [@file1_name, @file2_name] do
-      @argf.public_methods(false).should include(@method)
-    end
-  end
-
-  it "requires multiple arguments" do
-    argf [@file1_name, @file2_name] do
-      @argf.method(@method).arity.should < 0
-    end
-  end
-
-  it "reads each line of files" do
-    argf [@file1_name, @file2_name] do
-      lines = []
-      @argf.send(@method) { |b| lines << b }
-      lines.should == @lines
-    end
-  end
-
-  it "returns self when passed a block" do
-    argf [@file1_name, @file2_name] do
-      @argf.send(@method) {}.should equal(@argf)
-    end
-  end
-
-  describe "with a separator" do
-    it "yields each separated section of all streams" do
-      argf [@file1_name, @file2_name] do
-        @argf.send(@method, '.').to_a.should ==
-          (File.readlines(@file1_name, '.') + File.readlines(@file2_name, '.'))
-      end
-    end
-  end
-
-  describe "when no block is given" do
-    it "returns an Enumerator" do
-      argf [@file1_name, @file2_name] do
-        @argf.send(@method).should be_an_instance_of(Enumerator)
-      end
-    end
-
-    describe "returned Enumerator" do
-      describe "size" do
-        it "should return nil" do
-          argf [@file1_name, @file2_name] do
-            @argf.send(@method).size.should == nil
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/eof.rb b/spec/ruby/core/argf/shared/eof.rb
deleted file mode 100644
index 0e684f943f..0000000000
--- a/spec/ruby/core/argf/shared/eof.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-describe :argf_eof, shared: true do
-  before :each do
-    @file1 = fixture __FILE__, "file1.txt"
-    @file2 = fixture __FILE__, "file2.txt"
-  end
-
-  # NOTE: this test assumes that fixtures files have two lines each
-  it "returns true when reaching the end of a file" do
-    argf [@file1, @file2] do
-      result = []
-      while @argf.gets
-        result << @argf.send(@method)
-      end
-      result.should == [false, true, false, true]
-    end
-  end
-
-  it "raises IOError when called on a closed stream" do
-    argf [@file1] do
-      @argf.read
-      -> { @argf.send(@method) }.should raise_error(IOError)
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/filename.rb b/spec/ruby/core/argf/shared/filename.rb
deleted file mode 100644
index f47c673dc0..0000000000
--- a/spec/ruby/core/argf/shared/filename.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-describe :argf_filename, shared: true do
-  before :each do
-    @file1 = fixture __FILE__, "file1.txt"
-    @file2 = fixture __FILE__, "file2.txt"
-  end
-
-  # NOTE: this test assumes that fixtures files have two lines each
-  it "returns the current file name on each file" do
-    argf [@file1, @file2] do
-      result = []
-      # returns first current file even when not yet open
-      result << @argf.send(@method)
-      result << @argf.send(@method) while @argf.gets
-      # returns last current file even when closed
-      result << @argf.send(@method)
-
-      result.map! { |f| File.expand_path(f) }
-      result.should == [@file1, @file1, @file1, @file2, @file2, @file2]
-    end
-  end
-
-  # NOTE: this test assumes that fixtures files have two lines each
-  it "sets the $FILENAME global variable with the current file name on each file" do
-    script = fixture __FILE__, "filename.rb"
-    out = ruby_exe(script, args: [@file1, @file2])
-    out.should == "#{@file1}\n#{@file1}\n#{@file2}\n#{@file2}\n#{@file2}\n"
-  end
-end
diff --git a/spec/ruby/core/argf/shared/fileno.rb b/spec/ruby/core/argf/shared/fileno.rb
deleted file mode 100644
index 5d674048e2..0000000000
--- a/spec/ruby/core/argf/shared/fileno.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-describe :argf_fileno, shared: true do
-  before :each do
-    @file1 = fixture __FILE__, "file1.txt"
-    @file2 = fixture __FILE__, "file2.txt"
-  end
-
-  # NOTE: this test assumes that fixtures files have two lines each
-  it "returns the current file number on each file" do
-    argf [@file1, @file2] do
-      result = []
-      # returns first current file even when not yet open
-      result << @argf.send(@method) while @argf.gets
-      # returns last current file even when closed
-      result.map { |d| d.class }.should == [Fixnum, Fixnum, Fixnum, Fixnum]
-    end
-  end
-
-  it "raises an ArgumentError when called on a closed stream" do
-    argf [@file1] do
-      @argf.read
-      -> { @argf.send(@method) }.should raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/getc.rb b/spec/ruby/core/argf/shared/getc.rb
index 8be39c60b6..d63372d9d7 100644
--- a/spec/ruby/core/argf/shared/getc.rb
+++ b/spec/ruby/core/argf/shared/getc.rb
@@ -9,7 +9,7 @@ describe :argf_getc, shared: true do
 
   it "reads each char of files" do
     argf [@file1, @file2] do
-      chars = ""
+      chars = +""
       @chars.size.times { chars << @argf.send(@method) }
       chars.should == @chars
     end
diff --git a/spec/ruby/core/argf/shared/pos.rb b/spec/ruby/core/argf/shared/pos.rb
deleted file mode 100644
index 9836d5f1e4..0000000000
--- a/spec/ruby/core/argf/shared/pos.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-describe :argf_pos, shared: true do
-  before :each do
-    @file1 = fixture __FILE__, "file1.txt"
-    @file2 = fixture __FILE__, "file2.txt"
-  end
-
-  it "gives the correct position for each read operation" do
-    argf [@file1, @file2] do
-      size1 = File.size(@file1)
-      size2 = File.size(@file2)
-
-      @argf.read(2)
-      @argf.send(@method).should == 2
-      @argf.read(size1-2)
-      @argf.send(@method).should == size1
-      @argf.read(6)
-      @argf.send(@method).should == 6
-      @argf.rewind
-      @argf.send(@method).should == 0
-      @argf.read(size2)
-      @argf.send(@method).should == size2
-    end
-  end
-
-  it "raises an ArgumentError when called on a closed stream" do
-    argf [@file1] do
-      @argf.read
-      -> { @argf.send(@method) }.should raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/shared/read.rb b/spec/ruby/core/argf/shared/read.rb
index fe903983c0..e76d022139 100644
--- a/spec/ruby/core/argf/shared/read.rb
+++ b/spec/ruby/core/argf/shared/read.rb
@@ -15,7 +15,7 @@ describe :argf_read, shared: true do
 
   it "treats second argument as an output buffer" do
     argf [@file1_name] do
-      buffer = ""
+      buffer = +""
       @argf.send(@method, @file1.size, buffer)
       buffer.should == @file1
     end
@@ -23,7 +23,7 @@ describe :argf_read, shared: true do
 
   it "clears output buffer before appending to it" do
     argf [@file1_name] do
-      buffer = "to be cleared"
+      buffer = +"to be cleared"
       @argf.send(@method, @file1.size, buffer)
       buffer.should == @file1
     end
diff --git a/spec/ruby/core/argf/shared/readlines.rb b/spec/ruby/core/argf/shared/readlines.rb
deleted file mode 100644
index 505fa94acb..0000000000
--- a/spec/ruby/core/argf/shared/readlines.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-describe :argf_readlines, shared: true do
-  before :each do
-    @file1 = fixture __FILE__, "file1.txt"
-    @file2 = fixture __FILE__, "file2.txt"
-
-    @lines  = File.readlines(@file1)
-    @lines += File.readlines(@file2)
-  end
-
-  it "reads all lines of all files" do
-    argf [@file1, @file2] do
-      @argf.send(@method).should == @lines
-    end
-  end
-
-  it "returns an empty Array when end of stream reached" do
-    argf [@file1, @file2] do
-      @argf.read
-      @argf.send(@method).should == []
-    end
-  end
-end
diff --git a/spec/ruby/core/argf/skip_spec.rb b/spec/ruby/core/argf/skip_spec.rb
index 0181801c2d..bb1c0ae110 100644
--- a/spec/ruby/core/argf/skip_spec.rb
+++ b/spec/ruby/core/argf/skip_spec.rb
@@ -37,6 +37,6 @@ describe "ARGF.skip" do
   # which as a side-effect calls argf.file which will initialize
   # internals of ARGF enough for this to work.
   it "has no effect when nothing has been processed yet" do
-    -> { ARGF.class.new(@file1_name).skip }.should_not raise_error
+    -> { ARGF.class.new(@file1_name).skip }.should_not.raise
   end
 end
diff --git a/spec/ruby/core/argf/tell_spec.rb b/spec/ruby/core/argf/tell_spec.rb
index 16d9f29920..bb28df74a2 100644
--- a/spec/ruby/core/argf/tell_spec.rb
+++ b/spec/ruby/core/argf/tell_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/pos'
 
 describe "ARGF.tell" do
-  it_behaves_like :argf_pos, :tell
+  it "is an alias of ARGF.pos" do
+    ARGF.method(:tell).should == ARGF.method(:pos)
+  end
 end
diff --git a/spec/ruby/core/argf/to_a_spec.rb b/spec/ruby/core/argf/to_a_spec.rb
index b17a93db33..d95dc732ec 100644
--- a/spec/ruby/core/argf/to_a_spec.rb
+++ b/spec/ruby/core/argf/to_a_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/readlines'
 
 describe "ARGF.to_a" do
-  it_behaves_like :argf_readlines, :to_a
+  it "is an alias of ARGF.readlines" do
+    ARGF.method(:to_a).should == ARGF.method(:readlines)
+  end
 end
diff --git a/spec/ruby/core/argf/to_i_spec.rb b/spec/ruby/core/argf/to_i_spec.rb
index 2183de6cd4..e8df378f4e 100644
--- a/spec/ruby/core/argf/to_i_spec.rb
+++ b/spec/ruby/core/argf/to_i_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/fileno'
 
 describe "ARGF.to_i" do
-  it_behaves_like :argf_fileno, :to_i
+  it "is an alias of ARGF.fileno" do
+    ARGF.method(:to_i).should == ARGF.method(:fileno)
+  end
 end
diff --git a/spec/ruby/core/argf/to_io_spec.rb b/spec/ruby/core/argf/to_io_spec.rb
index 062383d291..ab5de58bcf 100644
--- a/spec/ruby/core/argf/to_io_spec.rb
+++ b/spec/ruby/core/argf/to_io_spec.rb
@@ -15,7 +15,7 @@ describe "ARGF.to_io" do
         result << @argf.to_io
       end
 
-      result.each { |io| io.should be_kind_of(IO) }
+      result.each { |io| io.should.is_a?(IO) }
       result[0].should == result[1]
       result[2].should == result[3]
     end
diff --git a/spec/ruby/core/array/all_spec.rb b/spec/ruby/core/array/all_spec.rb
new file mode 100644
index 0000000000..680e8c26fa
--- /dev/null
+++ b/spec/ruby/core/array/all_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
+
+describe "Array#all?" do
+  @value_to_return = -> _ { true }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :all?
+
+  it "ignores the block if there is an argument" do
+    -> {
+      ['bar', 'foobar'].all?(/bar/) { false }.should == true
+    }.should complain(/given block not used/)
+  end
+end
diff --git a/spec/ruby/core/array/allocate_spec.rb b/spec/ruby/core/array/allocate_spec.rb
index 04f7c0d0ad..c9eceef590 100644
--- a/spec/ruby/core/array/allocate_spec.rb
+++ b/spec/ruby/core/array/allocate_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Array.allocate" do
   it "returns an instance of Array" do
     ary = Array.allocate
-    ary.should be_an_instance_of(Array)
+    ary.should.instance_of?(Array)
   end
 
   it "returns a fully-formed instance of Array" do
@@ -14,6 +14,6 @@ describe "Array.allocate" do
   end
 
   it "does not accept any arguments" do
-    -> { Array.allocate(1) }.should raise_error(ArgumentError)
+    -> { Array.allocate(1) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/array/any_spec.rb b/spec/ruby/core/array/any_spec.rb
index 2fa5353e99..b51ce62f0f 100644
--- a/spec/ruby/core/array/any_spec.rb
+++ b/spec/ruby/core/array/any_spec.rb
@@ -1,24 +1,28 @@
 require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#any?" do
   describe 'with no block given (a default block of { |x| x } is implicit)' do
     it "is false if the array is empty" do
       empty_array = []
-      empty_array.any?.should == false
+      empty_array.should_not.any?
     end
 
     it "is false if the array is not empty, but all the members of the array are falsy" do
       falsy_array = [false, nil, false]
-      falsy_array.any?.should == false
+      falsy_array.should_not.any?
     end
 
     it "is true if the array has any truthy members" do
       not_empty_array = ['anything', nil]
-      not_empty_array.any?.should == true
+      not_empty_array.should.any?
     end
   end
 
   describe 'with a block given' do
+    @value_to_return = -> _ { false }
+    it_behaves_like :array_iterable_and_tolerating_size_increasing, :any?
+
     it 'is false if the array is empty' do
       empty_array = []
       empty_array.any? {|v| 1 == 1 }.should == false
@@ -34,4 +38,12 @@ describe "Array#any?" do
       array_with_members.any? {|v| v == 42 }.should == false
     end
   end
+
+  describe 'when given a pattern argument' do
+    it "ignores the block if there is an argument" do
+      -> {
+        ['bar', 'foobar'].any?(/bar/) { false }.should == true
+      }.should complain(/given block not used/)
+    end
+  end
 end
diff --git a/spec/ruby/core/array/append_spec.rb b/spec/ruby/core/array/append_spec.rb
index 302dc4a901..5480d9f65e 100644
--- a/spec/ruby/core/array/append_spec.rb
+++ b/spec/ruby/core/array/append_spec.rb
@@ -1,6 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/push'
 
 describe "Array#<<" do
   it "pushes the object onto the end of the array" do
@@ -10,8 +9,8 @@ describe "Array#<<" do
   it "returns self to allow chaining" do
     a = []
     b = a
-    (a << 1).should equal(b)
-    (a << 2 << 3).should equal(b)
+    (a << 1).should.equal?(b)
+    (a << 2 << 3).should.equal?(b)
   end
 
   it "correctly resizes the Array" do
@@ -30,13 +29,13 @@ describe "Array#<<" do
     a.should == [:foo]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array << 5 }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array << 5 }.should.raise(FrozenError)
   end
 end
 
-ruby_version_is "2.5" do
-  describe "Array#append" do
-    it_behaves_like :array_push, :append
+describe "Array#append" do
+  it "is an alias of Array#push" do
+    Array.instance_method(:append).should == Array.instance_method(:push)
   end
 end
diff --git a/spec/ruby/core/array/assoc_spec.rb b/spec/ruby/core/array/assoc_spec.rb
index f8479d763c..a5026cf5d4 100644
--- a/spec/ruby/core/array/assoc_spec.rb
+++ b/spec/ruby/core/array/assoc_spec.rb
@@ -6,18 +6,18 @@ describe "Array#assoc" do
     s1 = ["colors", "red", "blue", "green"]
     s2 = [:letters, "a", "b", "c"]
     s3 = [4]
-    s4 = ["colors", "cyan", "yellow", "magenda"]
+    s4 = ["colors", "cyan", "yellow", "magenta"]
     s5 = [:letters, "a", "i", "u"]
     s_nil = [nil, nil]
     a = [s1, s2, s3, s4, s5, s_nil]
-    a.assoc(s1.first).should equal(s1)
-    a.assoc(s2.first).should equal(s2)
-    a.assoc(s3.first).should equal(s3)
-    a.assoc(s4.first).should equal(s1)
-    a.assoc(s5.first).should equal(s2)
-    a.assoc(s_nil.first).should equal(s_nil)
-    a.assoc(4).should equal(s3)
-    a.assoc("key not in array").should be_nil
+    a.assoc(s1.first).should.equal?(s1)
+    a.assoc(s2.first).should.equal?(s2)
+    a.assoc(s3.first).should.equal?(s3)
+    a.assoc(s4.first).should.equal?(s1)
+    a.assoc(s5.first).should.equal?(s2)
+    a.assoc(s_nil.first).should.equal?(s_nil)
+    a.assoc(4).should.equal?(s3)
+    a.assoc("key not in array").should == nil
   end
 
   it "calls == on first element of each array" do
@@ -25,16 +25,28 @@ describe "Array#assoc" do
     key2 = mock('key2')
     items = [['not it', 1], [ArraySpecs::AssocKey.new, 2], ['na', 3]]
 
-    items.assoc(key1).should equal(items[1])
-    items.assoc(key2).should be_nil
+    items.assoc(key1).should.equal?(items[1])
+    items.assoc(key2).should == nil
   end
 
   it "ignores any non-Array elements" do
-    [1, 2, 3].assoc(2).should be_nil
+    [1, 2, 3].assoc(2).should == nil
     s1 = [4]
     s2 = [5, 4, 3]
     a = ["foo", [], s1, s2, nil, []]
-    a.assoc(s1.first).should equal(s1)
-    a.assoc(s2.first).should equal(s2)
+    a.assoc(s1.first).should.equal?(s1)
+    a.assoc(s2.first).should.equal?(s2)
+  end
+
+  it "calls to_ary on non-array elements" do
+    s1 = [1, 2]
+    s2 = ArraySpecs::ArrayConvertible.new(2, 3)
+    a = [s1, s2]
+
+    s1.should_not_receive(:to_ary)
+    a.assoc(s1.first).should.equal?(s1)
+
+    a.assoc(2).should == [2, 3]
+    s2.called.should.equal?(:to_ary)
   end
 end
diff --git a/spec/ruby/core/array/at_spec.rb b/spec/ruby/core/array/at_spec.rb
index 8bc789fef7..3c7c99fdff 100644
--- a/spec/ruby/core/array/at_spec.rb
+++ b/spec/ruby/core/array/at_spec.rb
@@ -47,10 +47,10 @@ describe "Array#at" do
   end
 
   it "raises a TypeError when the passed argument can't be coerced to Integer" do
-    -> { [].at("cat") }.should raise_error(TypeError)
+    -> { [].at("cat") }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when 2 or more arguments are passed" do
-    -> { [:a, :b].at(0,1) }.should raise_error(ArgumentError)
+    -> { [:a, :b].at(0,1) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/array/bsearch_index_spec.rb b/spec/ruby/core/array/bsearch_index_spec.rb
index aafded178d..e1d5eb66bb 100644
--- a/spec/ruby/core/array/bsearch_index_spec.rb
+++ b/spec/ruby/core/array/bsearch_index_spec.rb
@@ -8,11 +8,11 @@ describe "Array#bsearch_index" do
     end
 
     it "returns an Enumerator" do
-      @enum.should be_an_instance_of(Enumerator)
+      @enum.should.instance_of?(Enumerator)
     end
 
     it "returns an Enumerator with unknown size" do
-      @enum.size.should be_nil
+      @enum.size.should == nil
     end
 
     it "returns index of element when block condition is satisfied" do
@@ -21,11 +21,11 @@ describe "Array#bsearch_index" do
   end
 
   it "raises a TypeError when block returns a String" do
-    -> { [1, 2, 3].bsearch_index { "not ok" } }.should raise_error(TypeError)
+    -> { [1, 2, 3].bsearch_index { "not ok" } }.should.raise(TypeError)
   end
 
   it "returns nil when block is empty" do
-    [1, 2, 3].bsearch_index {}.should be_nil
+    [1, 2, 3].bsearch_index {}.should == nil
   end
 
   context "minimum mode" do
@@ -40,8 +40,8 @@ describe "Array#bsearch_index" do
     end
 
     it "returns nil when block condition is never satisfied" do
-      @array.bsearch_index { false }.should be_nil
-      @array.bsearch_index { |x| x >= 100 }.should be_nil
+      @array.bsearch_index { false }.should == nil
+      @array.bsearch_index { |x| x >= 100 }.should == nil
     end
   end
 
@@ -51,34 +51,30 @@ describe "Array#bsearch_index" do
     end
 
     it "returns the index of any matched elements where element is between 4 <= x < 8" do
-      [1, 2].should include(@array.bsearch_index { |x| 1 - x / 4 })
+      [1, 2].should.include?(@array.bsearch_index { |x| 1 - x / 4 })
     end
 
     it "returns the index of any matched elements where element is between 8 <= x < 10" do
-      @array.bsearch_index { |x| 4 - x / 2 }.should be_nil
+      @array.bsearch_index { |x| 4 - x / 2 }.should == nil
     end
 
     it "returns nil when block never returns 0" do
-      @array.bsearch_index { |x| 1 }.should be_nil
-      @array.bsearch_index { |x| -1 }.should be_nil
-    end
-
-    it "returns the middle element when block always returns zero" do
-      @array.bsearch_index { |x| 0 }.should == 2
+      @array.bsearch_index { |x| 1 }.should == nil
+      @array.bsearch_index { |x| -1 }.should == nil
     end
 
     context "magnitude does not effect the result" do
       it "returns the index of any matched elements where element is between 4n <= xn < 8n" do
-        [1, 2].should include(@array.bsearch_index { |x| (1 - x / 4) * (2**100) })
+        [1, 2].should.include?(@array.bsearch_index { |x| (1 - x / 4) * (2**100) })
       end
 
       it "returns nil when block never returns 0" do
-        @array.bsearch_index { |x| 1 * (2**100) }.should be_nil
-        @array.bsearch_index { |x| (-1) * (2**100) }.should be_nil
+        @array.bsearch_index { |x| 1 * (2**100) }.should == nil
+        @array.bsearch_index { |x| (-1) * (2**100) }.should == nil
       end
 
-      it "handles values from Bignum#coerce" do
-        [1, 2].should include(@array.bsearch_index { |x| (2**100).coerce((1 - x / 4) * (2**100)).first })
+      it "handles values from Integer#coerce" do
+        [1, 2].should.include?(@array.bsearch_index { |x| (2**100).coerce((1 - x / 4) * (2**100)).first })
       end
     end
   end
diff --git a/spec/ruby/core/array/bsearch_spec.rb b/spec/ruby/core/array/bsearch_spec.rb
index 8fa6245dbf..12aec60654 100644
--- a/spec/ruby/core/array/bsearch_spec.rb
+++ b/spec/ruby/core/array/bsearch_spec.rb
@@ -3,26 +3,26 @@ require_relative '../enumerable/shared/enumeratorized'
 
 describe "Array#bsearch" do
   it "returns an Enumerator when not passed a block" do
-    [1].bsearch.should be_an_instance_of(Enumerator)
+    [1].bsearch.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :enumeratorized_with_unknown_size, :bsearch, [1,2,3]
 
   it "raises a TypeError if the block returns an Object" do
-    -> { [1].bsearch { Object.new } }.should raise_error(TypeError)
+    -> { [1].bsearch { Object.new } }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the block returns a String" do
-    -> { [1].bsearch { "1" } }.should raise_error(TypeError)
+    -> { [1].bsearch { "1" } }.should.raise(TypeError)
   end
 
   context "with a block returning true or false" do
     it "returns nil if the block returns false for every element" do
-      [0, 1, 2, 3].bsearch { |x| x > 3 }.should be_nil
+      [0, 1, 2, 3].bsearch { |x| x > 3 }.should == nil
     end
 
     it "returns nil if the block returns nil for every element" do
-      [0, 1, 2, 3].bsearch { |x| nil }.should be_nil
+      [0, 1, 2, 3].bsearch { |x| nil }.should == nil
     end
 
     it "returns element at zero if the block returns true for every element" do
@@ -38,21 +38,21 @@ describe "Array#bsearch" do
 
   context "with a block returning negative, zero, positive numbers" do
     it "returns nil if the block returns less than zero for every element" do
-      [0, 1, 2, 3].bsearch { |x| x <=> 5 }.should be_nil
+      [0, 1, 2, 3].bsearch { |x| x <=> 5 }.should == nil
     end
 
     it "returns nil if the block returns greater than zero for every element" do
-      [0, 1, 2, 3].bsearch { |x| x <=> -1 }.should be_nil
+      [0, 1, 2, 3].bsearch { |x| x <=> -1 }.should == nil
 
     end
 
     it "returns nil if the block never returns zero" do
-      [0, 1, 3, 4].bsearch { |x| x <=> 2 }.should be_nil
+      [0, 1, 3, 4].bsearch { |x| x <=> 2 }.should == nil
     end
 
     it "accepts (+/-)Float::INFINITY from the block" do
-      [0, 1, 3, 4].bsearch { |x| Float::INFINITY }.should be_nil
-      [0, 1, 3, 4].bsearch { |x| -Float::INFINITY }.should be_nil
+      [0, 1, 3, 4].bsearch { |x| Float::INFINITY }.should == nil
+      [0, 1, 3, 4].bsearch { |x| -Float::INFINITY }.should == nil
     end
 
     it "returns an element at an index for which block returns 0.0" do
@@ -62,17 +62,17 @@ describe "Array#bsearch" do
 
     it "returns an element at an index for which block returns 0" do
       result = [0, 1, 2, 3, 4].bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
-      [1, 2].should include(result)
+      [1, 2].should.include?(result)
     end
   end
 
   context "with a block that calls break" do
     it "returns nil if break is called without a value" do
-      ['a', 'b', 'c'].bsearch { |v| break }.should be_nil
+      ['a', 'b', 'c'].bsearch { |v| break }.should == nil
     end
 
     it "returns nil if break is called with a nil value" do
-      ['a', 'b', 'c'].bsearch { |v| break nil }.should be_nil
+      ['a', 'b', 'c'].bsearch { |v| break nil }.should == nil
     end
 
     it "returns object if break is called with an object" do
diff --git a/spec/ruby/core/array/clear_spec.rb b/spec/ruby/core/array/clear_spec.rb
index 8f83a012b7..15778f864f 100644
--- a/spec/ruby/core/array/clear_spec.rb
+++ b/spec/ruby/core/array/clear_spec.rb
@@ -4,45 +4,29 @@ require_relative 'fixtures/classes'
 describe "Array#clear" do
   it "removes all elements" do
     a = [1, 2, 3, 4]
-    a.clear.should equal(a)
+    a.clear.should.equal?(a)
     a.should == []
   end
 
   it "returns self" do
     a = [1]
-    a.should equal a.clear
+    a.should.equal? a.clear
   end
 
   it "leaves the Array empty" do
     a = [1]
     a.clear
-    a.empty?.should == true
+    a.should.empty?
     a.size.should == 0
   end
 
-  it "keeps tainted status" do
-    a = [1]
-    a.taint
-    a.tainted?.should be_true
-    a.clear
-    a.tainted?.should be_true
-  end
-
   it "does not accept any arguments" do
-    -> { [1].clear(true) }.should raise_error(ArgumentError)
-  end
-
-  it "keeps untrusted status" do
-    a = [1]
-    a.untrust
-    a.untrusted?.should be_true
-    a.clear
-    a.untrusted?.should be_true
+    -> { [1].clear(true) }.should.raise(ArgumentError)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
+  it "raises a FrozenError on a frozen array" do
     a = [1]
     a.freeze
-    -> { a.clear }.should raise_error(frozen_error_class)
+    -> { a.clear }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/clone_spec.rb b/spec/ruby/core/array/clone_spec.rb
index 803e746e02..7ce9d40a81 100644
--- a/spec/ruby/core/array/clone_spec.rb
+++ b/spec/ruby/core/array/clone_spec.rb
@@ -12,8 +12,8 @@ describe "Array#clone" do
     aa = a.clone
     bb = b.clone
 
-    aa.frozen?.should == true
-    bb.frozen?.should == false
+    aa.should.frozen?
+    bb.should_not.frozen?
   end
 
   it "copies singleton methods" do
@@ -23,9 +23,9 @@ describe "Array#clone" do
     aa = a.clone
     bb = b.clone
 
-    a.respond_to?(:a_singleton_method).should be_true
-    b.respond_to?(:a_singleton_method).should be_false
-    aa.respond_to?(:a_singleton_method).should be_true
-    bb.respond_to?(:a_singleton_method).should be_false
+    a.respond_to?(:a_singleton_method).should == true
+    b.respond_to?(:a_singleton_method).should == false
+    aa.respond_to?(:a_singleton_method).should == true
+    bb.respond_to?(:a_singleton_method).should == false
   end
 end
diff --git a/spec/ruby/core/array/collect_spec.rb b/spec/ruby/core/array/collect_spec.rb
index 0ad4c283b1..43a539f805 100644
--- a/spec/ruby/core/array/collect_spec.rb
+++ b/spec/ruby/core/array/collect_spec.rb
@@ -1,11 +1,143 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/collect'
+require_relative '../enumerable/shared/enumeratorized'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#collect" do
-  it_behaves_like :array_collect, :collect
+  it "returns a copy of array with each element replaced by the value returned by block" do
+    a = ['a', 'b', 'c', 'd']
+    b = a.collect { |i| i + '!' }
+    b.should == ["a!", "b!", "c!", "d!"]
+    b.should_not.equal? a
+  end
+
+  it "does not return subclass instance" do
+    ArraySpecs::MyArray[1, 2, 3].collect { |x| x + 1 }.should.instance_of?(Array)
+  end
+
+  it "does not change self" do
+    a = ['a', 'b', 'c', 'd']
+    a.collect { |i| i + '!' }
+    a.should == ['a', 'b', 'c', 'd']
+  end
+
+  it "returns the evaluated value of block if it broke in the block" do
+    a = ['a', 'b', 'c', 'd']
+    b = a.collect {|i|
+      if i == 'c'
+        break 0
+      else
+        i + '!'
+      end
+    }
+    b.should == 0
+  end
+
+  it "returns an Enumerator when no block given" do
+    a = [1, 2, 3]
+    a.collect.should.instance_of?(Enumerator)
+  end
+
+  it "raises an ArgumentError when no block and with arguments" do
+    a = [1, 2, 3]
+    -> {
+      a.collect(:foo)
+    }.should.raise(ArgumentError)
+  end
+
+  before :each do
+    @object = [1, 2, 3, 4]
+  end
+  it_behaves_like :enumeratorized_with_origin_size, :collect
+
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :collect
 end
 
 describe "Array#collect!" do
-  it_behaves_like :array_collect_b, :collect!
+  it "replaces each element with the value returned by block" do
+    a = [7, 9, 3, 5]
+    a.collect! { |i| i - 1 }.should.equal?(a)
+    a.should == [6, 8, 2, 4]
+  end
+
+  it "returns self" do
+    a = [1, 2, 3, 4, 5]
+    b = a.collect! {|i| i+1 }
+    a.should.equal? b
+  end
+
+  it "returns the evaluated value of block but its contents is partially modified, if it broke in the block" do
+    a = ['a', 'b', 'c', 'd']
+    b = a.collect! {|i|
+      if i == 'c'
+        break 0
+      else
+        i + '!'
+      end
+    }
+    b.should == 0
+    a.should == ['a!', 'b!', 'c', 'd']
+  end
+
+  it "returns an Enumerator when no block given, and the enumerator can modify the original array" do
+    a = [1, 2, 3]
+    enum = a.collect!
+    enum.should.instance_of?(Enumerator)
+    enum.each{|i| "#{i}!" }
+    a.should == ["1!", "2!", "3!"]
+  end
+
+  describe "when frozen" do
+    it "raises a FrozenError" do
+      -> { ArraySpecs.frozen_array.collect! {} }.should.raise(FrozenError)
+    end
+
+    it "raises a FrozenError when empty" do
+      -> { ArraySpecs.empty_frozen_array.collect! {} }.should.raise(FrozenError)
+    end
+
+    it "raises a FrozenError when calling #each on the returned Enumerator" do
+      enumerator = ArraySpecs.frozen_array.collect!
+      -> { enumerator.each {|x| x } }.should.raise(FrozenError)
+    end
+
+    it "raises a FrozenError when calling #each on the returned Enumerator when empty" do
+      enumerator = ArraySpecs.empty_frozen_array.collect!
+      -> { enumerator.each {|x| x } }.should.raise(FrozenError)
+    end
+  end
+
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.collect! { raise StandardError, 'Oops' }
+    rescue
+    end
+
+    a.should == [1, 2, 3]
+  end
+
+  it "only changes elements before error is raised, keeping the element which raised an error." do
+    a = [1, 2, 3, 4]
+    begin
+      a.collect! do |e|
+        case e
+        when 1 then -1
+        when 2 then -2
+        when 3 then raise StandardError, 'Oops'
+        else 0
+        end
+      end
+    rescue StandardError
+    end
+
+    a.should == [-1, -2, 3, 4]
+  end
+
+  before :each do
+    @object = [1, 2, 3, 4]
+  end
+  it_behaves_like :enumeratorized_with_origin_size, :collect!
+
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :collect!
 end
diff --git a/spec/ruby/core/array/combination_spec.rb b/spec/ruby/core/array/combination_spec.rb
index f16d6f98fc..ac570687ca 100644
--- a/spec/ruby/core/array/combination_spec.rb
+++ b/spec/ruby/core/array/combination_spec.rb
@@ -6,11 +6,11 @@ describe "Array#combination" do
   end
 
   it "returns an enumerator when no block is provided" do
-    @array.combination(2).should be_an_instance_of(Enumerator)
+    @array.combination(2).should.instance_of?(Enumerator)
   end
 
   it "returns self when a block is given" do
-    @array.combination(2){}.should equal(@array)
+    @array.combination(2){}.should.equal?(@array)
   end
 
   it "yields nothing for out of bounds length and return self" do
@@ -30,7 +30,7 @@ describe "Array#combination" do
   it "yields a copy of self if the argument is the size of the receiver" do
     r = @array.combination(4).to_a
     r.should == [@array]
-    r[0].should_not equal(@array)
+    r[0].should_not.equal?(@array)
   end
 
   it "yields [] when length is 0" do
diff --git a/spec/ruby/core/array/compact_spec.rb b/spec/ruby/core/array/compact_spec.rb
index ecccddeb9f..dbcd16da35 100644
--- a/spec/ruby/core/array/compact_spec.rb
+++ b/spec/ruby/core/array/compact_spec.rb
@@ -15,63 +15,37 @@ describe "Array#compact" do
 
   it "does not return self" do
     a = [1, 2, 3]
-    a.compact.should_not equal(a)
+    a.compact.should_not.equal?(a)
   end
 
   it "does not return subclass instance for Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3, nil].compact.should be_an_instance_of(Array)
-  end
-
-  it "does not keep tainted status even if all elements are removed" do
-    a = [nil, nil]
-    a.taint
-    a.compact.tainted?.should be_false
-  end
-
-  it "does not keep untrusted status even if all elements are removed" do
-    a = [nil, nil]
-    a.untrust
-    a.compact.untrusted?.should be_false
+    ArraySpecs::MyArray[1, 2, 3, nil].compact.should.instance_of?(Array)
   end
 end
 
 describe "Array#compact!" do
   it "removes all nil elements" do
     a = ['a', nil, 'b', false, 'c']
-    a.compact!.should equal(a)
+    a.compact!.should.equal?(a)
     a.should == ["a", "b", false, "c"]
     a = [nil, 'a', 'b', false, 'c']
-    a.compact!.should equal(a)
+    a.compact!.should.equal?(a)
     a.should == ["a", "b", false, "c"]
     a = ['a', 'b', false, 'c', nil]
-    a.compact!.should equal(a)
+    a.compact!.should.equal?(a)
     a.should == ["a", "b", false, "c"]
   end
 
   it "returns self if some nil elements are removed" do
     a = ['a', nil, 'b', false, 'c']
-    a.compact!.should equal a
+    a.compact!.should.equal? a
   end
 
   it "returns nil if there are no nil elements to remove" do
     [1, 2, false, 3].compact!.should == nil
   end
 
-  it "keeps tainted status even if all elements are removed" do
-    a = [nil, nil]
-    a.taint
-    a.compact!
-    a.tainted?.should be_true
-  end
-
-  it "keeps untrusted status even if all elements are removed" do
-    a = [nil, nil]
-    a.untrust
-    a.compact!
-    a.untrusted?.should be_true
-  end
-
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.compact! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.compact! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/comparison_spec.rb b/spec/ruby/core/array/comparison_spec.rb
index 5d1c3265f1..14e8931e5a 100644
--- a/spec/ruby/core/array/comparison_spec.rb
+++ b/spec/ruby/core/array/comparison_spec.rb
@@ -92,6 +92,6 @@ describe "Array#<=>" do
   end
 
   it "returns nil when the argument is not array-like" do
-    ([] <=> false).should be_nil
+    ([] <=> false).should == nil
   end
 end
diff --git a/spec/ruby/core/array/concat_spec.rb b/spec/ruby/core/array/concat_spec.rb
index cc707d9948..1e8d20c36c 100644
--- a/spec/ruby/core/array/concat_spec.rb
+++ b/spec/ruby/core/array/concat_spec.rb
@@ -4,12 +4,12 @@ require_relative 'fixtures/classes'
 describe "Array#concat" do
   it "returns the array itself" do
     ary = [1,2,3]
-    ary.concat([4,5,6]).equal?(ary).should be_true
+    ary.concat([4,5,6]).equal?(ary).should == true
   end
 
   it "appends the elements in the other array" do
     ary = [1, 2, 3]
-    ary.concat([9, 10, 11]).should equal(ary)
+    ary.concat([9, 10, 11]).should.equal?(ary)
     ary.should == [1, 2, 3, 9, 10, 11]
     ary.concat([])
     ary.should == [1, 2, 3, 9, 10, 11]
@@ -32,69 +32,13 @@ describe "Array#concat" do
     [].concat(obj).should == [5, 6, 7]
   end
 
-  it "raises a #{frozen_error_class} when Array is frozen and modification occurs" do
-    -> { ArraySpecs.frozen_array.concat [1] }.should raise_error(frozen_error_class)
+  it "raises a FrozenError when Array is frozen and modification occurs" do
+    -> { ArraySpecs.frozen_array.concat [1] }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} when Array is frozen and no modification occurs" do
-    -> { ArraySpecs.frozen_array.concat([]) }.should raise_error(frozen_error_class)
-  end
-
-  it "keeps tainted status" do
-    ary = [1, 2]
-    ary.taint
-    ary.concat([3])
-    ary.tainted?.should be_true
-    ary.concat([])
-    ary.tainted?.should be_true
-  end
-
-  it "is not infected by the other" do
-    ary = [1,2]
-    other = [3]; other.taint
-    ary.tainted?.should be_false
-    ary.concat(other)
-    ary.tainted?.should be_false
-  end
-
-  it "keeps the tainted status of elements" do
-    ary = [ Object.new, Object.new, Object.new ]
-    ary.each {|x| x.taint }
-
-    ary.concat([ Object.new ])
-    ary[0].tainted?.should be_true
-    ary[1].tainted?.should be_true
-    ary[2].tainted?.should be_true
-    ary[3].tainted?.should be_false
-  end
-
-  it "keeps untrusted status" do
-    ary = [1, 2]
-    ary.untrust
-    ary.concat([3])
-    ary.untrusted?.should be_true
-    ary.concat([])
-    ary.untrusted?.should be_true
-  end
-
-  it "is not infected untrustedness by the other" do
-    ary = [1,2]
-    other = [3]; other.untrust
-    ary.untrusted?.should be_false
-    ary.concat(other)
-    ary.untrusted?.should be_false
-  end
-
-  it "keeps the untrusted status of elements" do
-    ary = [ Object.new, Object.new, Object.new ]
-    ary.each {|x| x.untrust }
-
-    ary.concat([ Object.new ])
-    ary[0].untrusted?.should be_true
-    ary[1].untrusted?.should be_true
-    ary[2].untrusted?.should be_true
-    ary[3].untrusted?.should be_false
+  it "raises a FrozenError when Array is frozen and no modification occurs" do
+    -> { ArraySpecs.frozen_array.concat([]) }.should.raise(FrozenError)
   end
 
   it "appends elements to an Array with enough capacity that has been shifted" do
@@ -124,7 +68,7 @@ describe "Array#concat" do
 
   it "returns self when given no arguments" do
     ary = [1, 2]
-    ary.concat.should equal(ary)
+    ary.concat.should.equal?(ary)
     ary.should == [1, 2]
   end
 end
diff --git a/spec/ruby/core/array/constructor_spec.rb b/spec/ruby/core/array/constructor_spec.rb
index 6f36074c45..c4398c535d 100644
--- a/spec/ruby/core/array/constructor_spec.rb
+++ b/spec/ruby/core/array/constructor_spec.rb
@@ -7,7 +7,7 @@ describe "Array.[]" do
     Array.[](5, true, nil, 'a', "Ruby", obj).should == [5, true, nil, "a", "Ruby", obj]
 
     a = ArraySpecs::MyArray.[](5, true, nil, 'a', "Ruby", obj)
-    a.should be_an_instance_of(ArraySpecs::MyArray)
+    a.should.instance_of?(ArraySpecs::MyArray)
     a.inspect.should == [5, true, nil, "a", "Ruby", obj].inspect
   end
 end
@@ -18,7 +18,7 @@ describe "Array[]" do
     Array[5, true, nil, 'a', "Ruby", obj].should == Array.[](5, true, nil, "a", "Ruby", obj)
 
     a = ArraySpecs::MyArray[5, true, nil, 'a', "Ruby", obj]
-    a.should be_an_instance_of(ArraySpecs::MyArray)
+    a.should.instance_of?(ArraySpecs::MyArray)
     a.inspect.should == [5, true, nil, "a", "Ruby", obj].inspect
   end
 end
diff --git a/spec/ruby/core/array/count_spec.rb b/spec/ruby/core/array/count_spec.rb
index eaf275aeb7..e778233c16 100644
--- a/spec/ruby/core/array/count_spec.rb
+++ b/spec/ruby/core/array/count_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#count" do
   it "returns the number of elements" do
@@ -12,4 +13,14 @@ describe "Array#count" do
   it "returns the number of element for which the block evaluates to true" do
     [:a, :b, :c].count { |s| s != :b }.should == 2
   end
+
+  it "ignores the block if there is an argument" do
+    -> {
+      [:a, :b, :b, :c].count(:b) { |e| e.size > 10 }.should == 2
+    }.should complain(/given block not used/)
+  end
+
+  context "when a block argument given" do
+    it_behaves_like :array_iterable_and_tolerating_size_increasing, :count
+  end
 end
diff --git a/spec/ruby/core/array/cycle_spec.rb b/spec/ruby/core/array/cycle_spec.rb
index 7219b49883..29284257e9 100644
--- a/spec/ruby/core/array/cycle_spec.rb
+++ b/spec/ruby/core/array/cycle_spec.rb
@@ -10,17 +10,17 @@ describe "Array#cycle" do
   end
 
   it "does not yield and returns nil when the array is empty and passed value is an integer" do
-    [].cycle(6, &@prc).should be_nil
+    [].cycle(6, &@prc).should == nil
     ScratchPad.recorded.should == []
   end
 
   it "does not yield and returns nil when the array is empty and passed value is nil" do
-    [].cycle(nil, &@prc).should be_nil
+    [].cycle(nil, &@prc).should == nil
     ScratchPad.recorded.should == []
   end
 
   it "does not yield and returns nil when passed 0" do
-    @array.cycle(0, &@prc).should be_nil
+    @array.cycle(0, &@prc).should == nil
     ScratchPad.recorded.should == []
   end
 
@@ -48,13 +48,13 @@ describe "Array#cycle" do
   it "does not rescue StopIteration when not passed a count" do
     -> do
       @array.cycle { raise StopIteration }
-    end.should raise_error(StopIteration)
+    end.should.raise(StopIteration)
   end
 
   it "does not rescue StopIteration when passed a count" do
     -> do
       @array.cycle(3) { raise StopIteration }
-    end.should raise_error(StopIteration)
+    end.should.raise(StopIteration)
   end
 
   it "iterates the array Integer(count) times when passed a Float count" do
@@ -74,23 +74,23 @@ describe "Array#cycle" do
     count = mock("cycle count 2")
     count.should_receive(:to_int).and_return("2")
 
-    -> { @array.cycle(count, &@prc) }.should raise_error(TypeError)
+    -> { @array.cycle(count, &@prc) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed a String" do
-    -> { @array.cycle("4") { } }.should raise_error(TypeError)
+    -> { @array.cycle("4") { } }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an Object" do
-    -> { @array.cycle(mock("cycle count")) { } }.should raise_error(TypeError)
+    -> { @array.cycle(mock("cycle count")) { } }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed true" do
-    -> { @array.cycle(true) { } }.should raise_error(TypeError)
+    -> { @array.cycle(true) { } }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false" do
-    -> { @array.cycle(false) { } }.should raise_error(TypeError)
+    -> { @array.cycle(false) { } }.should.raise(TypeError)
   end
 
   before :all do
diff --git a/spec/ruby/core/array/deconstruct_spec.rb b/spec/ruby/core/array/deconstruct_spec.rb
new file mode 100644
index 0000000000..11bb8e72c4
--- /dev/null
+++ b/spec/ruby/core/array/deconstruct_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+
+describe "Array#deconstruct" do
+  it "returns self" do
+    array = [1]
+
+    array.deconstruct.should.equal? array
+  end
+end
diff --git a/spec/ruby/core/array/delete_at_spec.rb b/spec/ruby/core/array/delete_at_spec.rb
index c3111fe3d8..1e298b6730 100644
--- a/spec/ruby/core/array/delete_at_spec.rb
+++ b/spec/ruby/core/array/delete_at_spec.rb
@@ -35,27 +35,7 @@ describe "Array#delete_at" do
     a.delete_at(-2).should == 1
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { [1,2,3].freeze.delete_at(0) }.should raise_error(frozen_error_class)
-  end
-
-  it "keeps tainted status" do
-    ary = [1, 2]
-    ary.taint
-    ary.tainted?.should be_true
-    ary.delete_at(0)
-    ary.tainted?.should be_true
-    ary.delete_at(0) # now empty
-    ary.tainted?.should be_true
-  end
-
-  it "keeps untrusted status" do
-    ary = [1, 2]
-    ary.untrust
-    ary.untrusted?.should be_true
-    ary.delete_at(0)
-    ary.untrusted?.should be_true
-    ary.delete_at(0) # now empty
-    ary.untrusted?.should be_true
+  it "raises a FrozenError on a frozen array" do
+    -> { [1,2,3].freeze.delete_at(0) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/delete_if_spec.rb b/spec/ruby/core/array/delete_if_spec.rb
index 9f22f7e086..701a612395 100644
--- a/spec/ruby/core/array/delete_if_spec.rb
+++ b/spec/ruby/core/array/delete_if_spec.rb
@@ -2,6 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/enumeratorize'
 require_relative 'shared/delete_if'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Array#delete_if" do
@@ -16,7 +17,7 @@ describe "Array#delete_if" do
   end
 
   it "returns self" do
-    @a.delete_if{ true }.equal?(@a).should be_true
+    @a.delete_if{ true }.equal?(@a).should == true
   end
 
   it_behaves_like :enumeratorize, :delete_if
@@ -24,43 +25,58 @@ describe "Array#delete_if" do
   it "returns self when called on an Array emptied with #shift" do
     array = [1]
     array.shift
-    array.delete_if { |x| true }.should equal(array)
+    array.delete_if { |x| true }.should.equal?(array)
   end
 
   it "returns an Enumerator if no block given, and the enumerator can modify the original array" do
     enum = @a.delete_if
-    enum.should be_an_instance_of(Enumerator)
-    @a.should_not be_empty
+    enum.should.instance_of?(Enumerator)
+    @a.should_not.empty?
     enum.each { true }
-    @a.should be_empty
+    @a.should.empty?
   end
 
   it "returns an Enumerator if no block given, and the array is frozen" do
-    @a.freeze.delete_if.should be_an_instance_of(Enumerator)
+    @a.freeze.delete_if.should.instance_of?(Enumerator)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.delete_if {} }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.delete_if {} }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.delete_if {} }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.delete_if {} }.should.raise(FrozenError)
   end
 
-  it "keeps tainted status" do
-    @a.taint
-    @a.tainted?.should be_true
-    @a.delete_if{ true }
-    @a.tainted?.should be_true
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.delete_if { raise StandardError, 'Oops' }
+    rescue
+    end
+
+    a.should == [1, 2, 3]
   end
 
-  it "keeps untrusted status" do
-    @a.untrust
-    @a.untrusted?.should be_true
-    @a.delete_if{ true }
-    @a.untrusted?.should be_true
+  it "only removes elements for which the block returns true, keeping the element which raised an error." do
+    a = [1, 2, 3, 4]
+    begin
+      a.delete_if do |e|
+        case e
+        when 2 then true
+        when 3 then raise StandardError, 'Oops'
+        else false
+        end
+      end
+    rescue StandardError
+    end
+
+    a.should == [1, 3, 4]
   end
 
   it_behaves_like :enumeratorized_with_origin_size, :delete_if, [1,2,3]
   it_behaves_like :delete_if, :delete_if
+
+  @value_to_return = -> _ { false }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :delete_if
 end
diff --git a/spec/ruby/core/array/delete_spec.rb b/spec/ruby/core/array/delete_spec.rb
index c55f4ad672..0d80b2839d 100644
--- a/spec/ruby/core/array/delete_spec.rb
+++ b/spec/ruby/core/array/delete_spec.rb
@@ -40,27 +40,7 @@ describe "Array#delete" do
     [1, 2, 3].freeze.delete(0).should == nil
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { [1, 2, 3].freeze.delete(1) }.should raise_error(frozen_error_class)
-  end
-
-  it "keeps tainted status" do
-    a = [1, 2]
-    a.taint
-    a.tainted?.should be_true
-    a.delete(2)
-    a.tainted?.should be_true
-    a.delete(1) # now empty
-    a.tainted?.should be_true
-  end
-
-  it "keeps untrusted status" do
-    a = [1, 2]
-    a.untrust
-    a.untrusted?.should be_true
-    a.delete(2)
-    a.untrusted?.should be_true
-    a.delete(1) # now empty
-    a.untrusted?.should be_true
+  it "raises a FrozenError on a frozen array" do
+    -> { [1, 2, 3].freeze.delete(1) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/difference_spec.rb b/spec/ruby/core/array/difference_spec.rb
index a357657967..63e32feca0 100644
--- a/spec/ruby/core/array/difference_spec.rb
+++ b/spec/ruby/core/array/difference_spec.rb
@@ -2,23 +2,21 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/difference'
 
-ruby_version_is "2.6" do
-  describe "Array#difference" do
-    it_behaves_like :array_binary_difference, :difference
+describe "Array#difference" do
+  it_behaves_like :array_binary_difference, :difference
 
-    it "returns a copy when called without any parameter" do
-      x = [1, 2, 3, 2]
-      x.difference.should == x
-      x.difference.should_not equal x
-    end
+  it "returns a copy when called without any parameter" do
+    x = [1, 2, 3, 2]
+    x.difference.should == x
+    x.difference.should_not.equal? x
+  end
 
-    it "does not return subclass instances for Array subclasses" do
-      ArraySpecs::MyArray[1, 2, 3].difference.should be_an_instance_of(Array)
-    end
+  it "does not return subclass instances for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].difference.should.instance_of?(Array)
+  end
 
-    it "accepts multiple arguments" do
-      x = [1, 2, 3, 1]
-      x.difference([], [0, 1], [3, 4], [3]).should == [2]
-    end
+  it "accepts multiple arguments" do
+    x = [1, 2, 3, 1]
+    x.difference([], [0, 1], [3, 4], [3]).should == [2]
   end
 end
diff --git a/spec/ruby/core/array/dig_spec.rb b/spec/ruby/core/array/dig_spec.rb
index f2d8ff47fd..4166ff9f1f 100644
--- a/spec/ruby/core/array/dig_spec.rb
+++ b/spec/ruby/core/array/dig_spec.rb
@@ -4,7 +4,7 @@ describe "Array#dig" do
 
   it "returns #at with one arg" do
     ['a'].dig(0).should == 'a'
-    ['a'].dig(1).should be_nil
+    ['a'].dig(1).should == nil
   end
 
   it "recurses array elements" do
@@ -22,20 +22,20 @@ describe "Array#dig" do
   it "raises a TypeError for a non-numeric index" do
     -> {
       ['a'].dig(:first)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError if any intermediate step does not respond to #dig" do
     a = [1, 2]
     -> {
       a.dig(0, 1)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if no arguments provided" do
     -> {
       [10].dig()
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "returns nil if any intermediate step is nil" do
diff --git a/spec/ruby/core/array/drop_spec.rb b/spec/ruby/core/array/drop_spec.rb
index 89b8534af4..c0e1c9edce 100644
--- a/spec/ruby/core/array/drop_spec.rb
+++ b/spec/ruby/core/array/drop_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#drop" do
   it "removes the specified number of elements from the start of the array" do
@@ -6,7 +7,7 @@ describe "Array#drop" do
   end
 
   it "raises an ArgumentError if the number of elements specified is negative" do
-   -> { [1, 2].drop(-3) }.should raise_error(ArgumentError)
+    -> { [1, 2].drop(-3) }.should.raise(ArgumentError)
   end
 
   it "returns an empty Array if all elements are dropped" do
@@ -30,4 +31,26 @@ describe "Array#drop" do
     ary.shift
     ary.drop(1).should == [2]
   end
+
+  it "tries to convert the passed argument to an Integer using #to_int" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(2)
+
+    [1, 2, 3].drop(obj).should == [3]
+  end
+
+  it "raises a TypeError when the passed argument can't be coerced to Integer" do
+    -> { [1, 2].drop("cat") }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the passed argument isn't an integer and #to_int returns non-Integer" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return("cat")
+
+    -> { [1, 2].drop(obj) }.should.raise(TypeError)
+  end
+
+  it 'returns a Array instance for Array subclasses' do
+    ArraySpecs::MyArray[1, 2, 3, 4, 5].drop(1).should.instance_of?(Array)
+  end
 end
diff --git a/spec/ruby/core/array/drop_while_spec.rb b/spec/ruby/core/array/drop_while_spec.rb
index cfb6b1e267..4fead3ff06 100644
--- a/spec/ruby/core/array/drop_while_spec.rb
+++ b/spec/ruby/core/array/drop_while_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#drop_while" do
+  @value_to_return = -> _ { true }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :drop_while
+
   it "removes elements from the start of the array while the block evaluates to true" do
     [1, 2, 3, 4].drop_while { |n| n < 4 }.should == [4]
   end
@@ -12,4 +17,8 @@ describe "Array#drop_while" do
   it "removes elements from the start of the array until the block returns false" do
     [1, 2, 3, false, 5].drop_while { |n| n }.should == [false, 5]
   end
+
+  it 'returns a Array instance for Array subclasses' do
+    ArraySpecs::MyArray[1, 2, 3, 4, 5].drop_while { |n| n < 4 }.should.instance_of?(Array)
+  end
 end
diff --git a/spec/ruby/core/array/dup_spec.rb b/spec/ruby/core/array/dup_spec.rb
index 17f467d5fc..f14aeca3b5 100644
--- a/spec/ruby/core/array/dup_spec.rb
+++ b/spec/ruby/core/array/dup_spec.rb
@@ -12,8 +12,8 @@ describe "Array#dup" do
     aa = a.dup
     bb = b.dup
 
-    aa.frozen?.should be_false
-    bb.frozen?.should be_false
+    aa.frozen?.should == false
+    bb.frozen?.should == false
   end
 
   it "does not copy singleton methods" do
@@ -23,9 +23,9 @@ describe "Array#dup" do
     aa = a.dup
     bb = b.dup
 
-    a.respond_to?(:a_singleton_method).should be_true
-    b.respond_to?(:a_singleton_method).should be_false
-    aa.respond_to?(:a_singleton_method).should be_false
-    bb.respond_to?(:a_singleton_method).should be_false
+    a.respond_to?(:a_singleton_method).should == true
+    b.respond_to?(:a_singleton_method).should == false
+    aa.respond_to?(:a_singleton_method).should == false
+    bb.respond_to?(:a_singleton_method).should == false
   end
 end
diff --git a/spec/ruby/core/array/each_index_spec.rb b/spec/ruby/core/array/each_index_spec.rb
index 51af5842c4..b238a89d8a 100644
--- a/spec/ruby/core/array/each_index_spec.rb
+++ b/spec/ruby/core/array/each_index_spec.rb
@@ -5,7 +5,7 @@ require_relative '../enumerable/shared/enumeratorized'
 
 # Modifying a collection while the contents are being iterated
 # gives undefined behavior. See
-# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/23633
+# https://blade.ruby-lang.org/ruby-core/23633
 
 describe "Array#each_index" do
   before :each do
@@ -20,7 +20,7 @@ describe "Array#each_index" do
 
   it "returns self" do
     a = [:a, :b, :c]
-    a.each_index { |i| }.should equal(a)
+    a.each_index { |i| }.should.equal?(a)
   end
 
   it "is not confused by removing elements from the front" do
@@ -40,3 +40,19 @@ describe "Array#each_index" do
   it_behaves_like :enumeratorize, :each_index
   it_behaves_like :enumeratorized_with_origin_size, :each_index, [1,2,3]
 end
+
+describe "Array#each_index" do
+  it "tolerates increasing an array size during iteration" do
+    array = [:a, :b, :c]
+    ScratchPad.record []
+    i = 0
+
+    array.each_index do |index|
+      ScratchPad << index
+      array << i if i < 100
+      i += 1
+    end
+
+    ScratchPad.recorded.should == (0..102).to_a # element indices
+  end
+end
diff --git a/spec/ruby/core/array/each_spec.rb b/spec/ruby/core/array/each_spec.rb
index 256647d61e..73a4c36b17 100644
--- a/spec/ruby/core/array/each_spec.rb
+++ b/spec/ruby/core/array/each_spec.rb
@@ -1,20 +1,50 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/enumeratorize'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 require_relative '../enumerable/shared/enumeratorized'
 
-# Modifying a collection while the contents are being iterated
-# gives undefined behavior. See
-# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/23633
+# Mutating the array while it is being iterated is discouraged as it can result in confusing behavior.
+# Yet a Ruby implementation must not crash in such a case, and following the simple CRuby behavior makes sense.
+# CRuby simply reads the array storage and checks the size for every iteration;
+# like `i = 0; while i < size; yield self[i]; i += 1; end`
 
 describe "Array#each" do
   it "yields each element to the block" do
     a = []
     x = [1, 2, 3]
-    x.each { |item| a << item }.should equal(x)
+    x.each { |item| a << item }.should.equal?(x)
     a.should == [1, 2, 3]
   end
 
+  it "yields each element to the block even if the array is changed during iteration" do
+    a = [1, 2, 3, 4, 5]
+    iterated = []
+    a.each { |x| iterated << x; a << x+5 if x.even? }
+    iterated.should == [1, 2, 3, 4, 5, 7, 9]
+  end
+
+  it "yields only elements that are still in the array" do
+    a = [0, 1, 2, 3, 4]
+    iterated = []
+    a.each { |x| iterated << x; a.pop if x.even? }
+    iterated.should == [0, 1, 2]
+  end
+
+  it "yields elements based on an internal index" do
+    a = [0, 1, 2, 3, 4]
+    iterated = []
+    a.each { |x| iterated << x; a.shift if x.even? }
+    iterated.should == [0, 2, 4]
+  end
+
+  it "yields the same element multiple times if inserting while iterating" do
+    a = [1, 2]
+    iterated = []
+    a.each { |x| iterated << x; a.unshift(0) if a.size == 2 }
+    iterated.should == [1, 1, 2]
+  end
+
   it "yields each element to a block that takes multiple arguments" do
     a = [[1, 2], :a, [3, 4]]
     b = []
@@ -46,3 +76,7 @@ describe "Array#each" do
   it_behaves_like :enumeratorize, :each
   it_behaves_like :enumeratorized_with_origin_size, :each, [1,2,3]
 end
+
+describe "Array#each" do
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :each
+end
diff --git a/spec/ruby/core/array/element_reference_spec.rb b/spec/ruby/core/array/element_reference_spec.rb
index 31e5578a09..d5f4b54961 100644
--- a/spec/ruby/core/array/element_reference_spec.rb
+++ b/spec/ruby/core/array/element_reference_spec.rb
@@ -1,9 +1,862 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/slice'
 
 describe "Array#[]" do
-  it_behaves_like :array_slice, :[]
+  it "returns the element at index with [index]" do
+    [ "a", "b", "c", "d", "e" ][1].should == "b"
+
+    a = [1, 2, 3, 4]
+
+    a[0].should == 1
+    a[1].should == 2
+    a[2].should == 3
+    a[3].should == 4
+    a[4].should == nil
+    a[10].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns the element at index from the end of the array with [-index]" do
+    [ "a", "b", "c", "d", "e" ][-2].should == "d"
+
+    a = [1, 2, 3, 4]
+
+    a[-1].should == 4
+    a[-2].should == 3
+    a[-3].should == 2
+    a[-4].should == 1
+    a[-5].should == nil
+    a[-10].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns count elements starting from index with [index, count]" do
+    [ "a", "b", "c", "d", "e" ][2, 3].should == ["c", "d", "e"]
+
+    a = [1, 2, 3, 4]
+
+    a[0, 0].should == []
+    a[0, 1].should == [1]
+    a[0, 2].should == [1, 2]
+    a[0, 4].should == [1, 2, 3, 4]
+    a[0, 6].should == [1, 2, 3, 4]
+    a[0, -1].should == nil
+    a[0, -2].should == nil
+    a[0, -4].should == nil
+
+    a[2, 0].should == []
+    a[2, 1].should == [3]
+    a[2, 2].should == [3, 4]
+    a[2, 4].should == [3, 4]
+    a[2, -1].should == nil
+
+    a[4, 0].should == []
+    a[4, 2].should == []
+    a[4, -1].should == nil
+
+    a[5, 0].should == nil
+    a[5, 2].should == nil
+    a[5, -1].should == nil
+
+    a[6, 0].should == nil
+    a[6, 2].should == nil
+    a[6, -1].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns count elements starting at index from the end of array with [-index, count]" do
+    [ "a", "b", "c", "d", "e" ][-2, 2].should == ["d", "e"]
+
+    a = [1, 2, 3, 4]
+
+    a[-1, 0].should == []
+    a[-1, 1].should == [4]
+    a[-1, 2].should == [4]
+    a[-1, -1].should == nil
+
+    a[-2, 0].should == []
+    a[-2, 1].should == [3]
+    a[-2, 2].should == [3, 4]
+    a[-2, 4].should == [3, 4]
+    a[-2, -1].should == nil
+
+    a[-4, 0].should == []
+    a[-4, 1].should == [1]
+    a[-4, 2].should == [1, 2]
+    a[-4, 4].should == [1, 2, 3, 4]
+    a[-4, 6].should == [1, 2, 3, 4]
+    a[-4, -1].should == nil
+
+    a[-5, 0].should == nil
+    a[-5, 1].should == nil
+    a[-5, 10].should == nil
+    a[-5, -1].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns the first count elements with [0, count]" do
+    [ "a", "b", "c", "d", "e" ][0, 3].should == ["a", "b", "c"]
+  end
+
+  it "returns the subarray which is independent to self with [index,count]" do
+    a = [1, 2, 3]
+    sub = a[1, 2]
+    sub.replace([:a, :b])
+    a.should == [1, 2, 3]
+  end
+
+  it "tries to convert the passed argument to an Integer using #to_int" do
+    obj = mock('to_int')
+    obj.stub!(:to_int).and_return(2)
+
+    a = [1, 2, 3, 4]
+    a[obj].should == 3
+    a[obj, 1].should == [3]
+    a[obj, obj].should == [3, 4]
+    a[0, obj].should == [1, 2]
+  end
+
+  it "raises TypeError if to_int returns non-integer" do
+    from = mock('from')
+    to = mock('to')
+
+    # So we can construct a range out of them...
+    def from.<=>(o) 0 end
+    def to.<=>(o) 0 end
+
+    a = [1, 2, 3, 4, 5]
+
+    def from.to_int() 'cat' end
+    def to.to_int() -2 end
+
+    -> { a[from..to] }.should.raise(TypeError)
+
+    def from.to_int() 1 end
+    def to.to_int() 'cat' end
+
+    -> { a[from..to] }.should.raise(TypeError)
+  end
+
+  it "returns the elements specified by Range indexes with [m..n]" do
+    [ "a", "b", "c", "d", "e" ][1..3].should == ["b", "c", "d"]
+    [ "a", "b", "c", "d", "e" ][4..-1].should == ['e']
+    [ "a", "b", "c", "d", "e" ][3..3].should == ['d']
+    [ "a", "b", "c", "d", "e" ][3..-2].should == ['d']
+    ['a'][0..-1].should == ['a']
+
+    a = [1, 2, 3, 4]
+
+    a[0..-10].should == []
+    a[0..0].should == [1]
+    a[0..1].should == [1, 2]
+    a[0..2].should == [1, 2, 3]
+    a[0..3].should == [1, 2, 3, 4]
+    a[0..4].should == [1, 2, 3, 4]
+    a[0..10].should == [1, 2, 3, 4]
+
+    a[2..-10].should == []
+    a[2..0].should == []
+    a[2..2].should == [3]
+    a[2..3].should == [3, 4]
+    a[2..4].should == [3, 4]
+
+    a[3..0].should == []
+    a[3..3].should == [4]
+    a[3..4].should == [4]
+
+    a[4..0].should == []
+    a[4..4].should == []
+    a[4..5].should == []
+
+    a[5..0].should == nil
+    a[5..5].should == nil
+    a[5..6].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns elements specified by Range indexes except the element at index n with [m...n]" do
+    [ "a", "b", "c", "d", "e" ][1...3].should == ["b", "c"]
+
+    a = [1, 2, 3, 4]
+
+    a[0...-10].should == []
+    a[0...0].should == []
+    a[0...1].should == [1]
+    a[0...2].should == [1, 2]
+    a[0...3].should == [1, 2, 3]
+    a[0...4].should == [1, 2, 3, 4]
+    a[0...10].should == [1, 2, 3, 4]
+
+    a[2...-10].should == []
+    a[2...0].should == []
+    a[2...2].should == []
+    a[2...3].should == [3]
+    a[2...4].should == [3, 4]
+
+    a[3...0].should == []
+    a[3...3].should == []
+    a[3...4].should == [4]
+
+    a[4...0].should == []
+    a[4...4].should == []
+    a[4...5].should == []
+
+    a[5...0].should == nil
+    a[5...5].should == nil
+    a[5...6].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns elements that exist if range start is in the array but range end is not with [m..n]" do
+    [ "a", "b", "c", "d", "e" ][4..7].should == ["e"]
+  end
+
+  it "accepts Range instances having a negative m and both signs for n with [m..n] and [m...n]" do
+    a = [1, 2, 3, 4]
+
+    a[-1..-1].should == [4]
+    a[-1...-1].should == []
+    a[-1..3].should == [4]
+    a[-1...3].should == []
+    a[-1..4].should == [4]
+    a[-1...4].should == [4]
+    a[-1..10].should == [4]
+    a[-1...10].should == [4]
+    a[-1..0].should == []
+    a[-1..-4].should == []
+    a[-1...-4].should == []
+    a[-1..-6].should == []
+    a[-1...-6].should == []
+
+    a[-2..-2].should == [3]
+    a[-2...-2].should == []
+    a[-2..-1].should == [3, 4]
+    a[-2...-1].should == [3]
+    a[-2..10].should == [3, 4]
+    a[-2...10].should == [3, 4]
+
+    a[-4..-4].should == [1]
+    a[-4..-2].should == [1, 2, 3]
+    a[-4...-2].should == [1, 2]
+    a[-4..-1].should == [1, 2, 3, 4]
+    a[-4...-1].should == [1, 2, 3]
+    a[-4..3].should == [1, 2, 3, 4]
+    a[-4...3].should == [1, 2, 3]
+    a[-4..4].should == [1, 2, 3, 4]
+    a[-4...4].should == [1, 2, 3, 4]
+    a[-4...4].should == [1, 2, 3, 4]
+    a[-4..0].should == [1]
+    a[-4...0].should == []
+    a[-4..1].should == [1, 2]
+    a[-4...1].should == [1]
+
+    a[-5..-5].should == nil
+    a[-5...-5].should == nil
+    a[-5..-4].should == nil
+    a[-5..-1].should == nil
+    a[-5..10].should == nil
+
+    a.should == [1, 2, 3, 4]
+  end
+
+  it "returns the subarray which is independent to self with [m..n]" do
+    a = [1, 2, 3]
+    sub = a[1..2]
+    sub.replace([:a, :b])
+    a.should == [1, 2, 3]
+  end
+
+  it "tries to convert Range elements to Integers using #to_int with [m..n] and [m...n]" do
+    from = mock('from')
+    to = mock('to')
+
+    # So we can construct a range out of them...
+    def from.<=>(o) 0 end
+    def to.<=>(o) 0 end
+
+    def from.to_int() 1 end
+    def to.to_int() -2 end
+
+    a = [1, 2, 3, 4]
+
+    a[from..to].should == [2, 3]
+    a[from...to].should == [2]
+    a[1..0].should == []
+    a[1...0].should == []
+
+    -> { a["a" .. "b"] }.should.raise(TypeError)
+    -> { a["a" ... "b"] }.should.raise(TypeError)
+    -> { a[from .. "b"] }.should.raise(TypeError)
+    -> { a[from ... "b"] }.should.raise(TypeError)
+  end
+
+  it "returns the same elements as [m..n] and [m...n] with Range subclasses" do
+    a = [1, 2, 3, 4]
+    range_incl = ArraySpecs::MyRange.new(1, 2)
+    range_excl = ArraySpecs::MyRange.new(-3, -1, true)
+
+    a[range_incl].should == [2, 3]
+    a[range_excl].should == [2, 3]
+  end
+
+  it "returns nil for a requested index not in the array with [index]" do
+    [ "a", "b", "c", "d", "e" ][5].should == nil
+  end
+
+  it "returns [] if the index is valid but length is zero with [index, length]" do
+    [ "a", "b", "c", "d", "e" ][0, 0].should == []
+    [ "a", "b", "c", "d", "e" ][2, 0].should == []
+  end
+
+  it "returns nil if length is zero but index is invalid with [index, length]" do
+    [ "a", "b", "c", "d", "e" ][100, 0].should == nil
+    [ "a", "b", "c", "d", "e" ][-50, 0].should == nil
+  end
+
+  # This is by design. It is in the official documentation.
+  it "returns [] if index == array.size with [index, length]" do
+    %w|a b c d e|[5, 2].should == []
+  end
+
+  it "returns nil if index > array.size with [index, length]" do
+    %w|a b c d e|[6, 2].should == nil
+  end
+
+  it "returns nil if length is negative with [index, length]" do
+    %w|a b c d e|[3, -1].should == nil
+    %w|a b c d e|[2, -2].should == nil
+    %w|a b c d e|[1, -100].should == nil
+  end
+
+  it "returns nil if no requested index is in the array with [m..n]" do
+    [ "a", "b", "c", "d", "e" ][6..10].should == nil
+  end
+
+  it "returns nil if range start is not in the array with [m..n]" do
+    [ "a", "b", "c", "d", "e" ][-10..2].should == nil
+    [ "a", "b", "c", "d", "e" ][10..12].should == nil
+  end
+
+  it "returns an empty array when m == n with [m...n]" do
+    [1, 2, 3, 4, 5][1...1].should == []
+  end
+
+  it "returns an empty array with [0...0]" do
+    [1, 2, 3, 4, 5][0...0].should == []
+  end
+
+  it "returns a subarray where m, n negatives and m < n with [m..n]" do
+    [ "a", "b", "c", "d", "e" ][-3..-2].should == ["c", "d"]
+  end
+
+  it "returns an array containing the first element with [0..0]" do
+    [1, 2, 3, 4, 5][0..0].should == [1]
+  end
+
+  it "returns the entire array with [0..-1]" do
+    [1, 2, 3, 4, 5][0..-1].should == [1, 2, 3, 4, 5]
+  end
+
+  it "returns all but the last element with [0...-1]" do
+    [1, 2, 3, 4, 5][0...-1].should == [1, 2, 3, 4]
+  end
+
+  it "returns [3] for [2..-1] out of [1, 2, 3]" do
+    [1,2,3][2..-1].should == [3]
+  end
+
+  it "returns an empty array when m > n and m, n are positive with [m..n]" do
+    [1, 2, 3, 4, 5][3..2].should == []
+  end
+
+  it "returns an empty array when m > n and m, n are negative with [m..n]" do
+    [1, 2, 3, 4, 5][-2..-3].should == []
+  end
+
+  it "does not expand array when the indices are outside of the array bounds" do
+    a = [1, 2]
+    a[4].should == nil
+    a.should == [1, 2]
+    a[4, 0].should == nil
+    a.should == [1, 2]
+    a[6, 1].should == nil
+    a.should == [1, 2]
+    a[8...8].should == nil
+    a.should == [1, 2]
+    a[10..10].should == nil
+    a.should == [1, 2]
+  end
+
+  describe "with a subclass of Array" do
+    before :each do
+      ScratchPad.clear
+
+      @array = ArraySpecs::MyArray[1, 2, 3, 4, 5]
+    end
+
+    it "returns a Array instance with [n, m]" do
+      @array[0, 2].should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n, m]" do
+      @array[-3, 2].should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [n..m]" do
+      @array[1..3].should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [n...m]" do
+      @array[1...3].should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n..-m]" do
+      @array[-3..-1].should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n...-m]" do
+      @array[-3...-1].should.instance_of?(Array)
+    end
+
+    it "returns an empty array when m == n with [m...n]" do
+      @array[1...1].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "returns an empty array with [0...0]" do
+      @array[0...0].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "returns an empty array when m > n and m, n are positive with [m..n]" do
+      @array[3..2].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "returns an empty array when m > n and m, n are negative with [m..n]" do
+      @array[-2..-3].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "returns [] if index == array.size with [index, length]" do
+      @array[5, 2].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "returns [] if the index is valid but length is zero with [index, length]" do
+      @array[0, 0].should == []
+      @array[2, 0].should == []
+      ScratchPad.recorded.should == nil
+    end
+
+    it "does not call #initialize on the subclass instance" do
+      @array[0, 3].should == [1, 2, 3]
+      ScratchPad.recorded.should == nil
+    end
+  end
+
+  it "raises a RangeError when the start index is out of range of Fixnum" do
+    array = [1, 2, 3, 4, 5, 6]
+    obj = mock('large value')
+    obj.should_receive(:to_int).and_return(bignum_value)
+    -> { array[obj] }.should.raise(RangeError)
+
+    obj = 8e19
+    -> { array[obj] }.should.raise(RangeError)
+
+    # boundary value when longs are 64 bits
+    -> { array[2.0**63] }.should.raise(RangeError)
+
+    # just under the boundary value when longs are 64 bits
+    array[max_long.to_f.prev_float].should == nil
+  end
+
+  it "raises a RangeError when the length is out of range of Fixnum" do
+    array = [1, 2, 3, 4, 5, 6]
+    obj = mock('large value')
+    obj.should_receive(:to_int).and_return(bignum_value)
+    -> { array[1, obj] }.should.raise(RangeError)
+
+    obj = 8e19
+    -> { array[1, obj] }.should.raise(RangeError)
+  end
+
+  it "raises a type error if a range is passed with a length" do
+    ->{ [1, 2, 3][1..2, 1] }.should.raise(TypeError)
+  end
+
+  it "raises a RangeError if passed a range with a bound that is too large" do
+    array = [1, 2, 3, 4, 5, 6]
+    -> { array[bignum_value..(bignum_value + 1)] }.should.raise(RangeError)
+    -> { array[0..bignum_value] }.should.raise(RangeError)
+  end
+
+  it "can accept endless ranges" do
+    a = [0, 1, 2, 3, 4, 5]
+    a[eval("(2..)")].should == [2, 3, 4, 5]
+    a[eval("(2...)")].should == [2, 3, 4, 5]
+    a[eval("(-2..)")].should == [4, 5]
+    a[eval("(-2...)")].should == [4, 5]
+    a[eval("(9..)")].should == nil
+    a[eval("(9...)")].should == nil
+    a[eval("(-9..)")].should == nil
+    a[eval("(-9...)")].should == nil
+  end
+
+  describe "can be sliced with Enumerator::ArithmeticSequence" do
+    before :each do
+      @array = [0, 1, 2, 3, 4, 5]
+    end
+
+    it "has endless range and positive steps" do
+      @array[eval("(0..).step(1)")].should == [0, 1, 2, 3, 4, 5]
+      @array[eval("(0..).step(2)")].should == [0, 2, 4]
+      @array[eval("(0..).step(10)")].should == [0]
+
+      @array[eval("(2..).step(1)")].should == [2, 3, 4, 5]
+      @array[eval("(2..).step(2)")].should == [2, 4]
+      @array[eval("(2..).step(10)")].should == [2]
+
+      @array[eval("(-3..).step(1)")].should == [3, 4, 5]
+      @array[eval("(-3..).step(2)")].should == [3, 5]
+      @array[eval("(-3..).step(10)")].should == [3]
+    end
+
+    it "has beginless range and positive steps" do
+      # end with zero index
+      @array[(..0).step(1)].should == [0]
+      @array[(...0).step(1)].should == []
+
+      @array[(..0).step(2)].should == [0]
+      @array[(...0).step(2)].should == []
+
+      @array[(..0).step(10)].should == [0]
+      @array[(...0).step(10)].should == []
+
+      # end with positive index
+      @array[(..3).step(1)].should == [0, 1, 2, 3]
+      @array[(...3).step(1)].should == [0, 1, 2]
+
+      @array[(..3).step(2)].should == [0, 2]
+      @array[(...3).step(2)].should == [0, 2]
+
+      @array[(..3).step(10)].should == [0]
+      @array[(...3).step(10)].should == [0]
+
+      # end with negative index
+      @array[(..-2).step(1)].should == [0, 1, 2, 3, 4,]
+      @array[(...-2).step(1)].should == [0, 1, 2, 3]
+
+      @array[(..-2).step(2)].should == [0, 2, 4]
+      @array[(...-2).step(2)].should == [0, 2]
+
+      @array[(..-2).step(10)].should == [0]
+      @array[(...-2).step(10)].should == [0]
+    end
+
+    it "has endless range and negative steps" do
+      @array[eval("(0..).step(-1)")].should == [0]
+      @array[eval("(0..).step(-2)")].should == [0]
+      @array[eval("(0..).step(-10)")].should == [0]
+
+      @array[eval("(2..).step(-1)")].should == [2, 1, 0]
+      @array[eval("(2..).step(-2)")].should == [2, 0]
+
+      @array[eval("(-3..).step(-1)")].should == [3, 2, 1, 0]
+      @array[eval("(-3..).step(-2)")].should == [3, 1]
+    end
+
+    it "has closed range and positive steps" do
+      # start and end with 0
+      @array[eval("(0..0).step(1)")].should == [0]
+      @array[eval("(0...0).step(1)")].should == []
+
+      @array[eval("(0..0).step(2)")].should == [0]
+      @array[eval("(0...0).step(2)")].should == []
+
+      @array[eval("(0..0).step(10)")].should == [0]
+      @array[eval("(0...0).step(10)")].should == []
+
+      # start and end with positive index
+      @array[eval("(1..3).step(1)")].should == [1, 2, 3]
+      @array[eval("(1...3).step(1)")].should == [1, 2]
+
+      @array[eval("(1..3).step(2)")].should == [1, 3]
+      @array[eval("(1...3).step(2)")].should == [1]
+
+      @array[eval("(1..3).step(10)")].should == [1]
+      @array[eval("(1...3).step(10)")].should == [1]
+
+      # start with positive index, end with negative index
+      @array[eval("(1..-2).step(1)")].should == [1, 2, 3, 4]
+      @array[eval("(1...-2).step(1)")].should == [1, 2, 3]
+
+      @array[eval("(1..-2).step(2)")].should ==  [1, 3]
+      @array[eval("(1...-2).step(2)")].should ==  [1, 3]
+
+      @array[eval("(1..-2).step(10)")].should == [1]
+      @array[eval("(1...-2).step(10)")].should == [1]
+
+      # start with negative index, end with positive index
+      @array[eval("(-4..4).step(1)")].should == [2, 3, 4]
+      @array[eval("(-4...4).step(1)")].should == [2, 3]
+
+      @array[eval("(-4..4).step(2)")].should == [2, 4]
+      @array[eval("(-4...4).step(2)")].should == [2]
+
+      @array[eval("(-4..4).step(10)")].should == [2]
+      @array[eval("(-4...4).step(10)")].should == [2]
+
+      # start with negative index, end with negative index
+      @array[eval("(-4..-2).step(1)")].should == [2, 3, 4]
+      @array[eval("(-4...-2).step(1)")].should == [2, 3]
+
+      @array[eval("(-4..-2).step(2)")].should == [2, 4]
+      @array[eval("(-4...-2).step(2)")].should == [2]
+
+      @array[eval("(-4..-2).step(10)")].should == [2]
+      @array[eval("(-4...-2).step(10)")].should == [2]
+    end
+
+    it "has closed range and negative steps" do
+      # start and end with 0
+      @array[eval("(0..0).step(-1)")].should == [0]
+      @array[eval("(0...0).step(-1)")].should == []
+
+      @array[eval("(0..0).step(-2)")].should == [0]
+      @array[eval("(0...0).step(-2)")].should == []
+
+      @array[eval("(0..0).step(-10)")].should == [0]
+      @array[eval("(0...0).step(-10)")].should == []
+
+      # start and end with positive index
+      @array[eval("(1..3).step(-1)")].should == []
+      @array[eval("(1...3).step(-1)")].should == []
+
+      @array[eval("(1..3).step(-2)")].should == []
+      @array[eval("(1...3).step(-2)")].should == []
+
+      @array[eval("(1..3).step(-10)")].should == []
+      @array[eval("(1...3).step(-10)")].should == []
+
+      # start with positive index, end with negative index
+      @array[eval("(1..-2).step(-1)")].should == []
+      @array[eval("(1...-2).step(-1)")].should == []
+
+      @array[eval("(1..-2).step(-2)")].should ==  []
+      @array[eval("(1...-2).step(-2)")].should ==  []
+
+      @array[eval("(1..-2).step(-10)")].should == []
+      @array[eval("(1...-2).step(-10)")].should == []
+
+      # start with negative index, end with positive index
+      @array[eval("(-4..4).step(-1)")].should == []
+      @array[eval("(-4...4).step(-1)")].should == []
+
+      @array[eval("(-4..4).step(-2)")].should == []
+      @array[eval("(-4...4).step(-2)")].should == []
+
+      @array[eval("(-4..4).step(-10)")].should == []
+      @array[eval("(-4...4).step(-10)")].should == []
+
+      # start with negative index, end with negative index
+      @array[eval("(-4..-2).step(-1)")].should == []
+      @array[eval("(-4...-2).step(-1)")].should == []
+
+      @array[eval("(-4..-2).step(-2)")].should == []
+      @array[eval("(-4...-2).step(-2)")].should == []
+
+      @array[eval("(-4..-2).step(-10)")].should == []
+      @array[eval("(-4...-2).step(-10)")].should == []
+    end
+
+    it "has inverted closed range and positive steps" do
+      # start and end with positive index
+      @array[eval("(3..1).step(1)")].should == []
+      @array[eval("(3...1).step(1)")].should == []
+
+      @array[eval("(3..1).step(2)")].should == []
+      @array[eval("(3...1).step(2)")].should == []
+
+      @array[eval("(3..1).step(10)")].should == []
+      @array[eval("(3...1).step(10)")].should == []
+
+      # start with negative index, end with positive index
+      @array[eval("(-2..1).step(1)")].should == []
+      @array[eval("(-2...1).step(1)")].should == []
+
+      @array[eval("(-2..1).step(2)")].should ==  []
+      @array[eval("(-2...1).step(2)")].should ==  []
+
+      @array[eval("(-2..1).step(10)")].should == []
+      @array[eval("(-2...1).step(10)")].should == []
+
+      # start with positive index, end with negative index
+      @array[eval("(4..-4).step(1)")].should == []
+      @array[eval("(4...-4).step(1)")].should == []
+
+      @array[eval("(4..-4).step(2)")].should == []
+      @array[eval("(4...-4).step(2)")].should == []
+
+      @array[eval("(4..-4).step(10)")].should == []
+      @array[eval("(4...-4).step(10)")].should == []
+
+      # start with negative index, end with negative index
+      @array[eval("(-2..-4).step(1)")].should == []
+      @array[eval("(-2...-4).step(1)")].should == []
+
+      @array[eval("(-2..-4).step(2)")].should == []
+      @array[eval("(-2...-4).step(2)")].should == []
+
+      @array[eval("(-2..-4).step(10)")].should == []
+      @array[eval("(-2...-4).step(10)")].should == []
+    end
+
+    it "has range with bounds outside of array" do
+      # end is equal to array's length
+      @array[(0..6).step(1)].should == [0, 1, 2, 3, 4, 5]
+      -> { @array[(0..6).step(2)] }.should.raise(RangeError)
+
+      # end is greater than length with positive steps
+      @array[(1..6).step(2)].should == [1, 3, 5]
+      @array[(2..7).step(2)].should == [2, 4]
+      -> { @array[(2..8).step(2)] }.should.raise(RangeError)
+
+      # begin is greater than length with negative steps
+      @array[(6..1).step(-2)].should == [5, 3, 1]
+      @array[(7..2).step(-2)].should == [5, 3]
+      -> { @array[(8..2).step(-2)] }.should.raise(RangeError)
+    end
+
+    it "has endless range with start outside of array's bounds" do
+      @array[eval("(6..).step(1)")].should == []
+      @array[eval("(7..).step(1)")].should == nil
+
+      @array[eval("(6..).step(2)")].should == []
+      -> { @array[eval("(7..).step(2)")] }.should.raise(RangeError)
+    end
+  end
+
+  it "can accept beginless ranges" do
+    a = [0, 1, 2, 3, 4, 5]
+    a[(..3)].should == [0, 1, 2, 3]
+    a[(...3)].should == [0, 1, 2]
+    a[(..-3)].should == [0, 1, 2, 3]
+    a[(...-3)].should == [0, 1, 2]
+    a[(..0)].should == [0]
+    a[(...0)].should == []
+    a[(..9)].should == [0, 1, 2, 3, 4, 5]
+    a[(...9)].should == [0, 1, 2, 3, 4, 5]
+    a[(..-9)].should == []
+    a[(...-9)].should == []
+  end
+
+  describe "can be sliced with Enumerator::ArithmeticSequence" do
+    it "with infinite/inverted ranges and negative steps" do
+      array = [0, 1, 2, 3, 4, 5]
+      array[(2..).step(-1)].should == [2, 1, 0]
+      array[(2..).step(-2)].should == [2, 0]
+      array[(2..).step(-3)].should == [2]
+      array[(2..).step(-4)].should == [2]
+
+      array[(-3..).step(-1)].should == [3, 2, 1, 0]
+      array[(-3..).step(-2)].should == [3, 1]
+      array[(-3..).step(-3)].should == [3, 0]
+      array[(-3..).step(-4)].should == [3]
+      array[(-3..).step(-5)].should == [3]
+
+      array[(..0).step(-1)].should == [5, 4, 3, 2, 1, 0]
+      array[(..0).step(-2)].should == [5, 3, 1]
+      array[(..0).step(-3)].should == [5, 2]
+      array[(..0).step(-4)].should == [5, 1]
+      array[(..0).step(-5)].should == [5, 0]
+      array[(..0).step(-6)].should == [5]
+      array[(..0).step(-7)].should == [5]
+
+      array[(...0).step(-1)].should == [5, 4, 3, 2, 1]
+      array[(...0).step(-2)].should == [5, 3, 1]
+      array[(...0).step(-3)].should == [5, 2]
+      array[(...0).step(-4)].should == [5, 1]
+      array[(...0).step(-5)].should == [5]
+      array[(...0).step(-6)].should == [5]
+
+      array[(...1).step(-1)].should == [5, 4, 3, 2]
+      array[(...1).step(-2)].should == [5, 3]
+      array[(...1).step(-3)].should == [5, 2]
+      array[(...1).step(-4)].should == [5]
+      array[(...1).step(-5)].should == [5]
+
+      array[(..-5).step(-1)].should == [5, 4, 3, 2, 1]
+      array[(..-5).step(-2)].should == [5, 3, 1]
+      array[(..-5).step(-3)].should == [5, 2]
+      array[(..-5).step(-4)].should == [5, 1]
+      array[(..-5).step(-5)].should == [5]
+      array[(..-5).step(-6)].should == [5]
+
+      array[(...-5).step(-1)].should == [5, 4, 3, 2]
+      array[(...-5).step(-2)].should == [5, 3]
+      array[(...-5).step(-3)].should == [5, 2]
+      array[(...-5).step(-4)].should == [5]
+      array[(...-5).step(-5)].should == [5]
+
+      array[(4..1).step(-1)].should == [4, 3, 2, 1]
+      array[(4..1).step(-2)].should == [4, 2]
+      array[(4..1).step(-3)].should == [4, 1]
+      array[(4..1).step(-4)].should == [4]
+      array[(4..1).step(-5)].should == [4]
+
+      array[(4...1).step(-1)].should == [4, 3, 2]
+      array[(4...1).step(-2)].should == [4, 2]
+      array[(4...1).step(-3)].should == [4]
+      array[(4...1).step(-4)].should == [4]
+
+      array[(-2..1).step(-1)].should == [4, 3, 2, 1]
+      array[(-2..1).step(-2)].should == [4, 2]
+      array[(-2..1).step(-3)].should == [4, 1]
+      array[(-2..1).step(-4)].should == [4]
+      array[(-2..1).step(-5)].should == [4]
+
+      array[(-2...1).step(-1)].should == [4, 3, 2]
+      array[(-2...1).step(-2)].should == [4, 2]
+      array[(-2...1).step(-3)].should == [4]
+      array[(-2...1).step(-4)].should == [4]
+
+      array[(4..-5).step(-1)].should == [4, 3, 2, 1]
+      array[(4..-5).step(-2)].should == [4, 2]
+      array[(4..-5).step(-3)].should == [4, 1]
+      array[(4..-5).step(-4)].should == [4]
+      array[(4..-5).step(-5)].should == [4]
+
+      array[(4...-5).step(-1)].should == [4, 3, 2]
+      array[(4...-5).step(-2)].should == [4, 2]
+      array[(4...-5).step(-3)].should == [4]
+      array[(4...-5).step(-4)].should == [4]
+
+      array[(-2..-5).step(-1)].should == [4, 3, 2, 1]
+      array[(-2..-5).step(-2)].should == [4, 2]
+      array[(-2..-5).step(-3)].should == [4, 1]
+      array[(-2..-5).step(-4)].should == [4]
+      array[(-2..-5).step(-5)].should == [4]
+
+      array[(-2...-5).step(-1)].should == [4, 3, 2]
+      array[(-2...-5).step(-2)].should == [4, 2]
+      array[(-2...-5).step(-3)].should == [4]
+      array[(-2...-5).step(-4)].should == [4]
+    end
+  end
+
+  it "can accept nil...nil ranges" do
+    a = [0, 1, 2, 3, 4, 5]
+    a[eval("(nil...nil)")].should == a
+    a[(...nil)].should == a
+    a[eval("(nil..)")].should == a
+  end
 end
 
 describe "Array.[]" do
@@ -39,12 +892,12 @@ describe "Array.[]" do
     end
 
     it "returns an instance of the subclass" do
-      ArraySpecs::MyArray[1, 2, 3].should be_an_instance_of(ArraySpecs::MyArray)
+      ArraySpecs::MyArray[1, 2, 3].should.instance_of?(ArraySpecs::MyArray)
     end
 
     it "does not call #initialize on the subclass instance" do
       ArraySpecs::MyArray[1, 2, 3].should == [1, 2, 3]
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/array/element_set_spec.rb b/spec/ruby/core/array/element_set_spec.rb
index 9375ff9b80..671e4338de 100644
--- a/spec/ruby/core/array/element_set_spec.rb
+++ b/spec/ruby/core/array/element_set_spec.rb
@@ -36,6 +36,7 @@ describe "Array#[]=" do
     a[3, 2] = ['a', 'b', 'c', 'd']
     a.should == [2, 2, 3, "a", "b", "c", "d", 6]
   end
+
   it "replaces the section defined by [start,length] with the given values" do
     a = [1, 2, 3, 4, 5, 6]
     a[3, 2] = 'a', 'b', 'c', 'd'
@@ -94,8 +95,8 @@ describe "Array#[]=" do
 
   it "checks frozen before attempting to coerce arguments" do
     a = [1,2,3,4].freeze
-    -> {a[:foo] = 1}.should raise_error(frozen_error_class)
-    -> {a[:foo, :bar] = 1}.should raise_error(frozen_error_class)
+    -> {a[:foo] = 1}.should.raise(FrozenError)
+    -> {a[:foo, :bar] = 1}.should.raise(FrozenError)
   end
 
   it "sets elements in the range arguments when passed ranges" do
@@ -169,6 +170,7 @@ describe "Array#[]=" do
     ary[1...1] = []
     ary.should == [1, 2, 3]
   end
+
   it "does nothing if the section defined by range has negative width and the rhs is an empty array" do
     ary = [1, 2, 3, 4, 5]
     ary[1...0] = []
@@ -195,25 +197,25 @@ describe "Array#[]=" do
 
     a[to .. from] = ["x"]
     a.should == [1, "a", "b", "x", "c", 4]
-    -> { a["a" .. "b"] = []  }.should raise_error(TypeError)
-    -> { a[from .. "b"] = [] }.should raise_error(TypeError)
+    -> { a["a" .. "b"] = []  }.should.raise(TypeError)
+    -> { a[from .. "b"] = [] }.should.raise(TypeError)
   end
 
   it "raises an IndexError when passed indexes out of bounds" do
     a = [1, 2, 3, 4]
-    -> { a[-5] = ""      }.should raise_error(IndexError)
-    -> { a[-5, -1] = ""  }.should raise_error(IndexError)
-    -> { a[-5, 0] = ""   }.should raise_error(IndexError)
-    -> { a[-5, 1] = ""   }.should raise_error(IndexError)
-    -> { a[-5, 2] = ""   }.should raise_error(IndexError)
-    -> { a[-5, 10] = ""  }.should raise_error(IndexError)
-
-    -> { a[-5..-5] = ""  }.should raise_error(RangeError)
-    -> { a[-5...-5] = "" }.should raise_error(RangeError)
-    -> { a[-5..-4] = ""  }.should raise_error(RangeError)
-    -> { a[-5...-4] = "" }.should raise_error(RangeError)
-    -> { a[-5..10] = ""  }.should raise_error(RangeError)
-    -> { a[-5...10] = "" }.should raise_error(RangeError)
+    -> { a[-5] = ""      }.should.raise(IndexError)
+    -> { a[-5, -1] = ""  }.should.raise(IndexError)
+    -> { a[-5, 0] = ""   }.should.raise(IndexError)
+    -> { a[-5, 1] = ""   }.should.raise(IndexError)
+    -> { a[-5, 2] = ""   }.should.raise(IndexError)
+    -> { a[-5, 10] = ""  }.should.raise(IndexError)
+
+    -> { a[-5..-5] = ""  }.should.raise(RangeError)
+    -> { a[-5...-5] = "" }.should.raise(RangeError)
+    -> { a[-5..-4] = ""  }.should.raise(RangeError)
+    -> { a[-5...-4] = "" }.should.raise(RangeError)
+    -> { a[-5..10] = ""  }.should.raise(RangeError)
+    -> { a[-5...10] = "" }.should.raise(RangeError)
 
     # ok
     a[0..-9] = [1]
@@ -236,8 +238,8 @@ describe "Array#[]=" do
     ary.should == [5, 6, 7]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array[0, 0] = [] }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array[0, 0] = [] }.should.raise(FrozenError)
   end
 end
 
@@ -284,6 +286,12 @@ describe "Array#[]= with [index, count]" do
     (a[2, 3] = [4, 5]).should == [4, 5]
   end
 
+  it "accepts a frozen String literal as RHS" do
+    a = ['a', 'b', 'c']
+    a[0, 2] = 'd'.freeze
+    a.should == ['d', 'c']
+  end
+
   it "just sets the section defined by [start,length] to nil even if the rhs is nil" do
     a = ['a', 'b', 'c', 'd', 'e']
     a[1, 3] = nil
@@ -323,6 +331,10 @@ describe "Array#[]= with [index, count]" do
     b = [1, 2, 3, 4, 5]
     b[10, 0] = [1]
     a.should == [1, 2, 3, 4, 5, nil, nil, nil, nil, nil, 1]
+
+    c = [1, 2, 3, 4, 5]
+    c[10, 0] = []
+    c.should == [1, 2, 3, 4, 5, nil, nil, nil, nil, nil]
   end
 
   it "inserts other section in place defined by idx" do
@@ -337,12 +349,12 @@ describe "Array#[]= with [index, count]" do
 
   it "raises an IndexError when passed start and negative length" do
     a = [1, 2, 3, 4]
-    -> { a[-2, -1] = "" }.should raise_error(IndexError)
-    -> { a[0, -1] = ""  }.should raise_error(IndexError)
-    -> { a[2, -1] = ""  }.should raise_error(IndexError)
-    -> { a[4, -1] = ""  }.should raise_error(IndexError)
-    -> { a[10, -1] = "" }.should raise_error(IndexError)
-    -> { [1, 2, 3, 4,  5][2, -1] = [7, 8] }.should raise_error(IndexError)
+    -> { a[-2, -1] = "" }.should.raise(IndexError)
+    -> { a[0, -1] = ""  }.should.raise(IndexError)
+    -> { a[2, -1] = ""  }.should.raise(IndexError)
+    -> { a[4, -1] = ""  }.should.raise(IndexError)
+    -> { a[10, -1] = "" }.should.raise(IndexError)
+    -> { [1, 2, 3, 4,  5][2, -1] = [7, 8] }.should.raise(IndexError)
   end
 end
 
@@ -396,6 +408,14 @@ describe "Array#[]= with [m..n]" do
     a.should == [1, 2, 3, 8, 4, 5]
   end
 
+  it "inserts at the end if m > the array size" do
+    a = [1, 2, 3]
+    a[3..3] = [4]
+    a.should == [1, 2, 3, 4]
+    a[5..7] = [6]
+    a.should == [1, 2, 3, 4, nil, 6]
+  end
+
   describe "Range subclasses" do
     before :each do
       @range_incl = ArraySpecs::MyRange.new(1, 2)
@@ -425,6 +445,87 @@ describe "Array#[]= with [m..n]" do
   end
 end
 
+describe "Array#[]= with [m..]" do
+  it "just sets the section defined by range to nil even if the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(2..)")] = nil
+    a.should == [1, 2, nil]
+  end
+
+  it "just sets the section defined by range to nil if m and n < 0 and the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(-3..)")] = nil
+    a.should == [1, 2, nil]
+  end
+
+  it "replaces the section defined by range" do
+    a = [6, 5, 4, 3, 2, 1]
+    a[eval("(3...)")] = 9
+    a.should == [6, 5, 4, 9]
+    a[eval("(2..)")] = [7, 7, 7]
+    a.should == [6, 5, 7, 7, 7]
+  end
+
+  it "replaces the section if m and n < 0" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(-3..)")] = [7, 8, 9]
+    a.should == [1, 2, 7, 8, 9]
+  end
+
+  it "inserts at the end if m > the array size" do
+    a = [1, 2, 3]
+    a[eval("(3..)")] = [4]
+    a.should == [1, 2, 3, 4]
+    a[eval("(5..)")] = [6]
+    a.should == [1, 2, 3, 4, nil, 6]
+  end
+end
+
+describe "Array#[]= with [..n] and [...n]" do
+  it "just sets the section defined by range to nil even if the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[(..2)] = nil
+    a.should == [nil, 4, 5]
+    a[(...2)] = nil
+    a.should == [nil, 5]
+  end
+
+  it "just sets the section defined by range to nil if n < 0 and the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[(..-3)] = nil
+    a.should == [nil, 4, 5]
+    a[(...-1)] = [nil, 5]
+  end
+
+  it "replaces the section defined by range" do
+    a = [6, 5, 4, 3, 2, 1]
+    a[(...3)] = 9
+    a.should == [9, 3, 2, 1]
+    a[(..2)] = [7, 7, 7, 7, 7]
+    a.should == [7, 7, 7, 7, 7, 1]
+  end
+
+  it "replaces the section if n < 0" do
+    a = [1, 2, 3, 4, 5]
+    a[(..-2)] = [7, 8, 9]
+    a.should == [7, 8, 9, 5]
+  end
+
+  it "replaces everything if n > the array size" do
+    a = [1, 2, 3]
+    a[(...7)] = [4]
+    a.should == [4]
+  end
+
+  it "inserts at the beginning if n < negative the array size" do
+    a = [1, 2, 3]
+    a[(..-7)] = [4]
+    a.should == [4, 1, 2, 3]
+    a[(...-10)] = [6]
+    a.should == [6, 4, 1, 2, 3]
+  end
+end
+
 describe "Array#[] after a shift" do
   it "works for insertion" do
     a = [1,2]
diff --git a/spec/ruby/core/array/empty_spec.rb b/spec/ruby/core/array/empty_spec.rb
index b5f3e8ed48..f70b1b6ebe 100644
--- a/spec/ruby/core/array/empty_spec.rb
+++ b/spec/ruby/core/array/empty_spec.rb
@@ -3,8 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "Array#empty?" do
   it "returns true if the array has no elements" do
-    [].empty?.should == true
-    [1].empty?.should == false
-    [1, 2].empty?.should == false
+    [].should.empty?
+    [1].should_not.empty?
+    [1, 2].should_not.empty?
   end
 end
diff --git a/spec/ruby/core/array/eql_spec.rb b/spec/ruby/core/array/eql_spec.rb
index 8565b94c60..9a7447c2e8 100644
--- a/spec/ruby/core/array/eql_spec.rb
+++ b/spec/ruby/core/array/eql_spec.rb
@@ -6,7 +6,7 @@ describe "Array#eql?" do
   it_behaves_like :array_eql, :eql?
 
   it "returns false if any corresponding elements are not #eql?" do
-    [1, 2, 3, 4].should_not eql([1, 2, 3, 4.0])
+    [1, 2, 3, 4].should_not.eql?([1, 2, 3, 4.0])
   end
 
   it "returns false if other is not a kind of Array" do
@@ -14,6 +14,6 @@ describe "Array#eql?" do
     obj.should_not_receive(:to_ary)
     obj.should_not_receive(:eql?)
 
-    [1, 2, 3].should_not eql(obj)
+    [1, 2, 3].should_not.eql?(obj)
   end
 end
diff --git a/spec/ruby/core/array/equal_value_spec.rb b/spec/ruby/core/array/equal_value_spec.rb
index a82e07b218..4f7c0ce5e3 100644
--- a/spec/ruby/core/array/equal_value_spec.rb
+++ b/spec/ruby/core/array/equal_value_spec.rb
@@ -10,17 +10,17 @@ describe "Array#==" do
     obj.should_receive(:respond_to?).at_least(1).with(:to_ary).and_return(true)
     obj.should_receive(:==).with([1]).at_least(1).and_return(true)
 
-    ([1] == obj).should be_true
-    ([[1]] == [obj]).should be_true
-    ([[[1], 3], 2] == [[obj, 3], 2]).should be_true
+    ([1] == obj).should == true
+    ([[1]] == [obj]).should == true
+    ([[[1], 3], 2] == [[obj, 3], 2]).should == true
 
     # recursive arrays
     arr1 = [[1]]
     arr1 << arr1
     arr2 = [obj]
     arr2 << arr2
-    (arr1 == arr2).should be_true
-    (arr2 == arr1).should be_true
+    (arr1 == arr2).should == true
+    (arr2 == arr1).should == true
   end
 
   it "returns false if any corresponding elements are not #==" do
diff --git a/spec/ruby/core/array/fetch_spec.rb b/spec/ruby/core/array/fetch_spec.rb
index b81c0b48d7..ee94cfcbb2 100644
--- a/spec/ruby/core/array/fetch_spec.rb
+++ b/spec/ruby/core/array/fetch_spec.rb
@@ -12,9 +12,9 @@ describe "Array#fetch" do
   end
 
   it "raises an IndexError if there is no element at index" do
-    -> { [1, 2, 3].fetch(3) }.should raise_error(IndexError)
-    -> { [1, 2, 3].fetch(-4) }.should raise_error(IndexError)
-    -> { [].fetch(0) }.should raise_error(IndexError)
+    -> { [1, 2, 3].fetch(3) }.should.raise(IndexError, "index 3 outside of array bounds: -3...3")
+    -> { [1, 2, 3].fetch(-4) }.should.raise(IndexError, "index -4 outside of array bounds: -3...3")
+    -> { [].fetch(0) }.should.raise(IndexError, "index 0 outside of array bounds: 0...0")
   end
 
   it "returns default if there is no element at index if passed a default value" do
@@ -33,7 +33,7 @@ describe "Array#fetch" do
     o = mock('5')
     def o.to_int(); 5; end
 
-    [1, 2, 3].fetch(o) { |i| i }.should equal(o)
+    [1, 2, 3].fetch(o) { |i| i }.should.equal?(o)
   end
 
   it "gives precedence to the default block over the default argument" do
@@ -50,6 +50,6 @@ describe "Array#fetch" do
   end
 
   it "raises a TypeError when the passed argument can't be coerced to Integer" do
-    -> { [].fetch("cat") }.should raise_error(TypeError)
+    -> { [].fetch("cat") }.should.raise(TypeError, "no implicit conversion of String into Integer")
   end
 end
diff --git a/spec/ruby/core/array/fetch_values_spec.rb b/spec/ruby/core/array/fetch_values_spec.rb
new file mode 100644
index 0000000000..237d6ad7f7
--- /dev/null
+++ b/spec/ruby/core/array/fetch_values_spec.rb
@@ -0,0 +1,55 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Array#fetch_values" do
+  before :each do
+    @array = [:a, :b, :c]
+  end
+
+  ruby_version_is "3.4" do
+    describe "with matched indexes" do
+      it "returns the values for indexes" do
+        @array.fetch_values(0).should == [:a]
+        @array.fetch_values(0, 2).should == [:a, :c]
+        @array.fetch_values(-1).should == [:c]
+      end
+
+      it "returns the values for indexes ordered in the order of the requested indexes" do
+        @array.fetch_values(2, 0).should == [:c, :a]
+      end
+    end
+
+    describe "with unmatched indexes" do
+      it "raises a index error if no block is provided" do
+        -> { @array.fetch_values(0, 1, 44) }.should.raise(IndexError, "index 44 outside of array bounds: -3...3")
+      end
+
+      it "returns the default value from block" do
+        @array.fetch_values(44) { |index| "`#{index}' is not found" }.should == ["`44' is not found"]
+        @array.fetch_values(0, 44) { |index| "`#{index}' is not found" }.should == [:a, "`44' is not found"]
+      end
+    end
+
+    describe "without keys" do
+      it "returns an empty Array" do
+        @array.fetch_values.should == []
+      end
+    end
+
+    it "tries to convert the passed argument to an Integer using #to_int" do
+      obj = mock('to_int')
+      obj.should_receive(:to_int).and_return(2)
+      @array.fetch_values(obj).should == [:c]
+    end
+
+    it "does not support a Range object as argument" do
+      -> {
+        @array.fetch_values(1..2)
+      }.should.raise(TypeError, "no implicit conversion of Range into Integer")
+    end
+
+    it "raises a TypeError when the passed argument can't be coerced to Integer" do
+      -> { [].fetch_values("cat") }.should.raise(TypeError, "no implicit conversion of String into Integer")
+    end
+  end
+end
diff --git a/spec/ruby/core/array/fill_spec.rb b/spec/ruby/core/array/fill_spec.rb
index 1c1beef25e..e4d51bd998 100644
--- a/spec/ruby/core/array/fill_spec.rb
+++ b/spec/ruby/core/array/fill_spec.rb
@@ -10,7 +10,7 @@ describe "Array#fill" do
 
   it "returns self" do
     ary = [1, 2, 3]
-    ary.fill(:a).should equal(ary)
+    ary.fill(:a).should.equal?(ary)
   end
 
   it "is destructive" do
@@ -21,14 +21,14 @@ describe "Array#fill" do
 
   it "does not replicate the filler" do
     ary = [1, 2, 3, 4]
-    str = "x"
+    str = +"x"
     ary.fill(str).should == [str, str, str, str]
     str << "y"
     ary.should == [str, str, str, str]
-    ary[0].should equal(str)
-    ary[1].should equal(str)
-    ary[2].should equal(str)
-    ary[3].should equal(str)
+    ary[0].should.equal?(str)
+    ary[1].should.equal?(str)
+    ary[2].should.equal?(str)
+    ary[3].should.equal?(str)
   end
 
   it "replaces all elements in the array with the filler if not given a index nor a length" do
@@ -43,34 +43,72 @@ describe "Array#fill" do
     [nil, nil, nil, nil].fill { |i| i * 2 }.should == [0, 2, 4, 6]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.fill('x') }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.fill('x') }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.fill('x') }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.fill('x') }.should.raise(FrozenError)
   end
 
   it "raises an ArgumentError if 4 or more arguments are passed when no block given" do
-    -> { [].fill('a') }.should_not raise_error(ArgumentError)
-
-    -> { [].fill('a', 1) }.should_not raise_error(ArgumentError)
-
-    -> { [].fill('a', 1, 2) }.should_not raise_error(ArgumentError)
-    -> { [].fill('a', 1, 2, true) }.should raise_error(ArgumentError)
+    [].fill('a').should == []
+    [].fill('a', 1).should == []
+    [].fill('a', 1, 2).should == [nil, 'a', 'a']
+    -> { [].fill('a', 1, 2, true) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if no argument passed and no block given" do
-    -> { [].fill }.should raise_error(ArgumentError)
+    -> { [].fill }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if 3 or more arguments are passed when a block given" do
-    -> { [].fill() {|i|} }.should_not raise_error(ArgumentError)
+    [].fill() {|i|}.should == []
+    [].fill(1) {|i|}.should == []
+    [].fill(1, 2) {|i|}.should == [nil, nil, nil]
+    -> { [].fill(1, 2, true) {|i|} }.should.raise(ArgumentError)
+  end
+
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.fill { raise StandardError, 'Oops' }
+    rescue
+    end
 
-    -> { [].fill(1) {|i|} }.should_not raise_error(ArgumentError)
+    a.should == [1, 2, 3]
+  end
+
+  it "only changes elements before error is raised, keeping the element which raised an error." do
+    a = [1, 2, 3, 4]
+    begin
+      a.fill do |i|
+        case i
+        when 0 then -1
+        when 1 then -2
+        when 2 then raise StandardError, 'Oops'
+        else 0
+        end
+      end
+    rescue StandardError
+    end
 
-    -> { [].fill(1, 2) {|i|} }.should_not raise_error(ArgumentError)
-    -> { [].fill(1, 2, true) {|i|} }.should raise_error(ArgumentError)
+    a.should == [-1, -2, 3, 4]
+  end
+
+  it "tolerates increasing an array size during iteration" do
+    array = [:a, :b, :c]
+    ScratchPad.record []
+    i = 0
+
+    array.fill do |index|
+      ScratchPad << index
+      array << i if i < 100
+      i++
+      index
+    end
+
+    ScratchPad.recorded.should == [0, 1, 2]
   end
 end
 
@@ -169,25 +207,25 @@ describe "Array#fill with (filler, index, length)" do
     [1, 2, 3, 4, 5].fill(-2, -2, &@never_passed).should == [1, 2, 3, 4, 5]
   end
 
-  # See: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/17481
+  # See: https://blade.ruby-lang.org/ruby-core/17481
   it "does not raise an exception if the given length is negative and its absolute value does not exceed the index" do
-    -> { [1, 2, 3, 4].fill('a', 3, -1)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill('a', 3, -2)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill('a', 3, -3)}.should_not raise_error(ArgumentError)
+    [1, 2, 3, 4].fill('a', 3, -1).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill('a', 3, -2).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill('a', 3, -3).should == [1, 2, 3, 4]
 
-    -> { [1, 2, 3, 4].fill(3, -1, &@never_passed)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill(3, -2, &@never_passed)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill(3, -3, &@never_passed)}.should_not raise_error(ArgumentError)
+    [1, 2, 3, 4].fill(3, -1, &@never_passed).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill(3, -2, &@never_passed).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill(3, -3, &@never_passed).should == [1, 2, 3, 4]
   end
 
   it "does not raise an exception even if the given length is negative and its absolute value exceeds the index" do
-    -> { [1, 2, 3, 4].fill('a', 3, -4)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill('a', 3, -5)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill('a', 3, -10000)}.should_not raise_error(ArgumentError)
+    [1, 2, 3, 4].fill('a', 3, -4).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill('a', 3, -5).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill('a', 3, -10000).should == [1, 2, 3, 4]
 
-    -> { [1, 2, 3, 4].fill(3, -4, &@never_passed)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill(3, -5, &@never_passed)}.should_not raise_error(ArgumentError)
-    -> { [1, 2, 3, 4].fill(3, -10000, &@never_passed)}.should_not raise_error(ArgumentError)
+    [1, 2, 3, 4].fill(3, -4, &@never_passed).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill(3, -5, &@never_passed).should == [1, 2, 3, 4]
+    [1, 2, 3, 4].fill(3, -10000, &@never_passed).should == [1, 2, 3, 4]
   end
 
   it "tries to convert the second and third arguments to Integers using #to_int" do
@@ -199,17 +237,24 @@ describe "Array#fill with (filler, index, length)" do
   end
 
   it "raises a TypeError if the index is not numeric" do
-    -> { [].fill 'a', true }.should raise_error(TypeError)
+    -> { [].fill 'a', true }.should.raise(TypeError)
 
     obj = mock('nonnumeric')
-    -> { [].fill('a', obj) }.should raise_error(TypeError)
+    -> { [].fill('a', obj) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the length is not numeric" do
+    -> { [1, 2, 3].fill("x", 1, "foo") }.should.raise(TypeError, /no implicit conversion of String into Integer/)
+    -> { [1, 2, 3].fill("x", 1, :"foo") }.should.raise(TypeError, /no implicit conversion of Symbol into Integer/)
+    -> { [1, 2, 3].fill("x", 1, Object.new) }.should.raise(TypeError, /no implicit conversion of Object into Integer/)
   end
 
   not_supported_on :opal do
     it "raises an ArgumentError or RangeError for too-large sizes" do
+      error_types = [RangeError, ArgumentError]
       arr = [1, 2, 3]
-      -> { arr.fill(10, 1, fixnum_max) }.should raise_error(ArgumentError)
-      -> { arr.fill(10, 1, bignum_value) }.should raise_error(RangeError)
+      -> { arr.fill(10, 1, fixnum_max) }.should.raise { |err| error_types.should.include?(err.class) }
+      -> { arr.fill(10, 1, bignum_value) }.should.raise(RangeError)
     end
   end
 end
@@ -239,7 +284,7 @@ describe "Array#fill with (filler, range)" do
   end
 
   it "raises a TypeError with range and length argument" do
-    -> { [].fill('x', 0 .. 2, 5) }.should raise_error(TypeError)
+    -> { [].fill('x', 0 .. 2, 5) }.should.raise(TypeError)
   end
 
   it "replaces elements between the (-m)th to the last and the (n+1)th from the first if given an range m..n where m < 0 and n >= 0" do
@@ -291,13 +336,13 @@ describe "Array#fill with (filler, range)" do
   end
 
   it "raises an exception if some of the given range lies before the first of the array" do
-    -> { [1, 2, 3].fill('x', -5..-3) }.should raise_error(RangeError)
-    -> { [1, 2, 3].fill('x', -5...-3) }.should raise_error(RangeError)
-    -> { [1, 2, 3].fill('x', -5..-4) }.should raise_error(RangeError)
+    -> { [1, 2, 3].fill('x', -5..-3) }.should.raise(RangeError)
+    -> { [1, 2, 3].fill('x', -5...-3) }.should.raise(RangeError)
+    -> { [1, 2, 3].fill('x', -5..-4) }.should.raise(RangeError)
 
-    -> { [1, 2, 3].fill(-5..-3, &@never_passed) }.should raise_error(RangeError)
-    -> { [1, 2, 3].fill(-5...-3, &@never_passed) }.should raise_error(RangeError)
-    -> { [1, 2, 3].fill(-5..-4, &@never_passed) }.should raise_error(RangeError)
+    -> { [1, 2, 3].fill(-5..-3, &@never_passed) }.should.raise(RangeError)
+    -> { [1, 2, 3].fill(-5...-3, &@never_passed) }.should.raise(RangeError)
+    -> { [1, 2, 3].fill(-5..-4, &@never_passed) }.should.raise(RangeError)
   end
 
   it "tries to convert the start and end of the passed range to Integers using #to_int" do
@@ -312,6 +357,18 @@ describe "Array#fill with (filler, range)" do
   it "raises a TypeError if the start or end of the passed range is not numeric" do
     obj = mock('nonnumeric')
     def obj.<=>(rhs); rhs == self ? 0 : nil end
-    -> { [].fill('a', obj..obj) }.should raise_error(TypeError)
+    -> { [].fill('a', obj..obj) }.should.raise(TypeError)
+  end
+
+  it "works with endless ranges" do
+    [1, 2, 3, 4].fill('x', eval("(1..)")).should == [1, 'x', 'x', 'x']
+    [1, 2, 3, 4].fill('x', eval("(3...)")).should == [1, 2, 3, 'x']
+    [1, 2, 3, 4].fill(eval("(1..)")) { |x| x + 2 }.should == [1, 3, 4, 5]
+    [1, 2, 3, 4].fill(eval("(3...)")) { |x| x + 2 }.should == [1, 2, 3, 5]
+  end
+
+  it "works with beginless ranges" do
+    [1, 2, 3, 4].fill('x', (..2)).should == ["x", "x", "x", 4]
+    [1, 2, 3, 4].fill((...2)) { |x| x + 2 }.should == [2, 3, 3, 4]
   end
 end
diff --git a/spec/ruby/core/array/filter_spec.rb b/spec/ruby/core/array/filter_spec.rb
index ee4f71ca28..6ebda61069 100644
--- a/spec/ruby/core/array/filter_spec.rb
+++ b/spec/ruby/core/array/filter_spec.rb
@@ -1,16 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Array#filter" do
-    it_behaves_like :array_select, :filter
+describe "Array#filter" do
+  it "is an alias of Array#select" do
+    Array.instance_method(:filter).should == Array.instance_method(:select)
   end
+end
 
-  describe "Array#filter!" do
-    it "returns nil if no changes were made in the array" do
-      [1, 2, 3].filter! { true }.should be_nil
-    end
-
-    it_behaves_like :keep_if, :filter!
+describe "Array#filter!" do
+  it "is an alias of Array#select!" do
+    Array.instance_method(:filter!).should == Array.instance_method(:select!)
   end
 end
diff --git a/spec/ruby/core/array/find_index_spec.rb b/spec/ruby/core/array/find_index_spec.rb
index 759472024a..17ff6c04a7 100644
--- a/spec/ruby/core/array/find_index_spec.rb
+++ b/spec/ruby/core/array/find_index_spec.rb
@@ -1,6 +1,42 @@
 require_relative '../../spec_helper'
-require_relative 'shared/index'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#find_index" do
-  it_behaves_like :array_index, :find_index
+  it "returns the index of the first element == to object" do
+    x = mock('3')
+    def x.==(obj) 3 == obj; end
+
+    [2, x, 3, 1, 3, 1].find_index(3).should == 1
+    [2, 3.0, 3, x, 1, 3, 1].find_index(x).should == 1
+  end
+
+  it "returns 0 if first element == to object" do
+    [2, 1, 3, 2, 5].find_index(2).should == 0
+  end
+
+  it "returns size-1 if only last element == to object" do
+    [2, 1, 3, 1, 5].find_index(5).should == 4
+  end
+
+  it "returns nil if no element == to object" do
+    [2, 1, 1, 1, 1].find_index(3).should == nil
+  end
+
+  it "accepts a block instead of an argument" do
+    [4, 2, 1, 5, 1, 3].find_index {|x| x < 2}.should == 2
+  end
+
+  it "ignores the block if there is an argument" do
+    -> {
+      [4, 2, 1, 5, 1, 3].find_index(5) {|x| x < 2}.should == 3
+    }.should complain(/given block not used/)
+  end
+
+  describe "given no argument and no block" do
+    it "produces an Enumerator" do
+      [].find_index.should.instance_of?(Enumerator)
+    end
+  end
+
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :find_index
 end
diff --git a/spec/ruby/core/array/first_spec.rb b/spec/ruby/core/array/first_spec.rb
index 66eeba6565..2c343ac8f6 100644
--- a/spec/ruby/core/array/first_spec.rb
+++ b/spec/ruby/core/array/first_spec.rb
@@ -30,11 +30,11 @@ describe "Array#first" do
   end
 
   it "raises an ArgumentError when count is negative" do
-    -> { [1, 2].first(-1) }.should raise_error(ArgumentError)
+    -> { [1, 2].first(-1) }.should.raise(ArgumentError)
   end
 
   it "raises a RangeError when count is a Bignum" do
-    -> { [].first(bignum_value) }.should raise_error(RangeError)
+    -> { [].first(bignum_value) }.should.raise(RangeError)
   end
 
   it "returns the entire array when count > length" do
@@ -53,10 +53,10 @@ describe "Array#first" do
 
   it "properly handles recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
-    empty.first.should equal(empty)
+    empty.first.should.equal?(empty)
 
     ary = ArraySpecs.head_recursive_array
-    ary.first.should equal(ary)
+    ary.first.should.equal?(ary)
   end
 
   it "tries to convert the passed argument to an Integer using #to_int" do
@@ -66,19 +66,19 @@ describe "Array#first" do
   end
 
   it "raises a TypeError if the passed argument is not numeric" do
-    -> { [1,2].first(nil) }.should raise_error(TypeError)
-    -> { [1,2].first("a") }.should raise_error(TypeError)
+    -> { [1,2].first(nil) }.should.raise(TypeError)
+    -> { [1,2].first("a") }.should.raise(TypeError)
 
     obj = mock("nonnumeric")
-    -> { [1,2].first(obj) }.should raise_error(TypeError)
+    -> { [1,2].first(obj) }.should.raise(TypeError)
   end
 
   it "does not return subclass instance when passed count on Array subclasses" do
-    ArraySpecs::MyArray[].first(0).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[].first(2).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].first(0).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].first(1).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].first(2).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[].first(0).should.instance_of?(Array)
+    ArraySpecs::MyArray[].first(2).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].first(0).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].first(1).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].first(2).should.instance_of?(Array)
   end
 
   it "is not destructive" do
diff --git a/spec/ruby/core/array/fixtures/classes.rb b/spec/ruby/core/array/fixtures/classes.rb
index 42071ed0cd..05283c0f74 100644
--- a/spec/ruby/core/array/fixtures/classes.rb
+++ b/spec/ruby/core/array/fixtures/classes.rb
@@ -40,6 +40,62 @@ module ArraySpecs
     a
   end
 
+  # Chi squared critical values for tests with n degrees of freedom at 99% confidence.
+  # Values obtained from NIST Engineering Statistic Handbook at
+  # https://www.itl.nist.gov/div898/handbook/eda/section3/eda3674.htm
+
+  CHI_SQUARED_CRITICAL_VALUES = [
+    0,
+    6.635, 9.210, 11.345, 13.277, 15.086, 16.812, 18.475, 20.090, 21.666, 23.209,
+    24.725, 26.217, 27.688, 29.141, 30.578, 32.000, 33.409, 34.805, 36.191, 37.566,
+    38.932, 40.289, 41.638, 42.980, 44.314, 45.642, 46.963, 48.278, 49.588, 50.892,
+    52.191, 53.486, 54.776, 56.061, 57.342, 58.619, 59.893, 61.162, 62.428, 63.691,
+    64.950, 66.206, 67.459, 68.710, 69.957, 71.201, 72.443, 73.683, 74.919, 76.154,
+    77.386, 78.616, 79.843, 81.069, 82.292, 83.513, 84.733, 85.950, 87.166, 88.379,
+    89.591, 90.802, 92.010, 93.217, 94.422, 95.626, 96.828, 98.028, 99.228, 100.425,
+    101.621, 102.816, 104.010, 105.202, 106.393, 107.583, 108.771, 109.958, 111.144, 112.329,
+    113.512, 114.695, 115.876, 117.057, 118.236, 119.414, 120.591, 121.767, 122.942, 124.116,
+    125.289, 126.462, 127.633, 128.803, 129.973, 131.141, 132.309, 133.476, 134.642, 135.807,
+  ]
+
+  def self.measure_sample_fairness(size, samples, iters)
+    ary = Array.new(size) { |x| x }
+    expected = iters.fdiv size
+    (samples).times do |i|
+      chi_results = []
+      3.times do
+        counts = Array.new(size, 0)
+        iters.times do
+          x = ary.sample(samples)[i]
+          counts[x] += 1
+        end
+        chi_squared = counts.sum {|count| (count - expected) ** 2} / expected
+        chi_results << chi_squared
+        break if chi_squared <= CHI_SQUARED_CRITICAL_VALUES[size]
+      end
+
+      chi_results.min.should <= CHI_SQUARED_CRITICAL_VALUES[size]
+    end
+  end
+
+  def self.measure_sample_fairness_large_sample_size(size, samples, iters)
+    ary = Array.new(size) { |x| x }
+    counts = Array.new(size, 0)
+    expected = (iters * samples).fdiv size
+    iters.times do
+      ary.sample(samples).each do |sample|
+        counts[sample] += 1
+      end
+    end
+    chi_squared = counts.sum {|count| (count - expected) ** 2} / expected
+
+    # Chi squared critical values for tests with 4 degrees of freedom
+    # Values obtained from NIST Engineering Statistic Handbook at
+    # https://www.itl.nist.gov/div898/handbook/eda/section3/eda3674.htm
+
+    chi_squared.should <= CHI_SQUARED_CRITICAL_VALUES[size]
+  end
+
   class MyArray < Array
     # The #initialize method has a different signature than Array to help
     # catch places in the specs that do not assert the #initialize is not
@@ -98,6 +154,16 @@ module ArraySpecs
     end
   end
 
+  class ArrayMethodMissing
+    def initialize(*values, &block)
+      @values = values;
+    end
+
+    def method_missing(name, *args)
+      @values
+    end
+  end
+
   class SortSame
     def <=>(other); 0; end
     def ==(other); true; end
@@ -126,7 +192,7 @@ module ArraySpecs
     attr_accessor :order
   end
 
-  class ComparableWithFixnum
+  class ComparableWithInteger
     include Comparable
     def initialize(num)
       @num = num
@@ -144,373 +210,377 @@ module ArraySpecs
   end
 
   def self.universal_pack_object
-    obj = mock("string float int")
+    obj = mock("string float int".freeze)
     obj.stub!(:to_int).and_return(1)
     obj.stub!(:to_str).and_return("1")
     obj.stub!(:to_f).and_return(1.0)
     obj
   end
 
-  LargeArray = ["test_create_table_with_force_true_does_not_drop_nonexisting_table",
- "test_add_table",
- "assert_difference",
- "assert_operator",
- "instance_variables",
- "class",
- "instance_variable_get",
- "__class__",
- "expects",
- "assert_no_difference",
- "name",
- "assert_blank",
- "assert_not_same",
- "is_a?",
- "test_add_table_with_decimals",
- "test_create_table_with_timestamps_should_create_datetime_columns",
- "assert_present",
- "assert_no_match",
- "__instance_of__",
- "assert_deprecated",
- "assert",
- "assert_throws",
- "kind_of?",
- "try",
- "__instance_variable_get__",
- "object_id",
- "timeout",
- "instance_variable_set",
- "assert_nothing_thrown",
- "__instance_variable_set__",
- "copy_object",
- "test_create_table_with_timestamps_should_create_datetime_columns_with_options",
- "assert_not_deprecated",
- "assert_in_delta",
- "id",
- "copy_metaclass",
- "test_create_table_without_a_block",
- "dup",
- "assert_not_nil",
- "send",
- "__instance_variables__",
- "to_sql",
- "mock",
- "assert_send",
- "instance_variable_defined?",
- "clone",
- "require",
- "test_migrator",
- "__instance_variable_defined_eh__",
- "frozen?",
- "test_add_column_not_null_with_default",
- "freeze",
- "test_migrator_one_up",
- "test_migrator_one_down",
- "singleton_methods",
- "method_exists?",
- "create_fixtures",
- "test_migrator_one_up_one_down",
- "test_native_decimal_insert_manual_vs_automatic",
- "instance_exec",
- "__is_a__",
- "test_migrator_double_up",
- "stub",
- "private_methods",
- "stubs",
- "test_migrator_double_down",
- "fixture_path",
- "private_singleton_methods",
- "stub_everything",
- "test_migrator_one_up_with_exception_and_rollback",
- "sequence",
- "protected_methods",
- "enum_for",
- "test_finds_migrations",
- "run_before_mocha",
- "states",
- "protected_singleton_methods",
- "to_json",
- "instance_values",
- "==",
- "mocha_setup",
- "public_methods",
- "test_finds_pending_migrations",
- "mocha_verify",
- "assert_kind_of",
- "===",
- "=~",
- "test_relative_migrations",
- "mocha_teardown",
- "gem",
- "mocha",
- "test_only_loads_pending_migrations",
- "test_add_column_with_precision_and_scale",
- "require_or_load",
- "eql?",
- "require_dependency",
- "test_native_types",
- "test_target_version_zero_should_run_only_once",
- "extend",
- "to_matcher",
- "unloadable",
- "require_association",
- "hash",
- "__id__",
- "load_dependency",
- "equals",
- "test_migrator_db_has_no_schema_migrations_table",
- "test_migrator_verbosity",
- "kind_of",
- "to_yaml",
- "to_bool",
- "test_migrator_verbosity_off",
- "taint",
- "test_migrator_going_down_due_to_version_target",
- "tainted?",
- "mocha_inspect",
- "test_migrator_rollback",
- "vim",
- "untaint",
- "taguri=",
- "test_migrator_forward",
- "test_schema_migrations_table_name",
- "test_proper_table_name",
- "all_of",
- "test_add_drop_table_with_prefix_and_suffix",
- "_setup_callbacks",
- "setup",
- "Not",
- "test_create_table_with_binary_column",
- "assert_not_equal",
- "enable_warnings",
- "acts_like?",
- "Rational",
- "_removed_setup_callbacks",
- "Table",
- "bind",
- "any_of",
- "__method__",
- "test_migrator_with_duplicates",
- "_teardown_callbacks",
- "method",
- "test_migrator_with_duplicate_names",
- "_removed_teardown_callbacks",
- "any_parameters",
- "test_migrator_with_missing_version_numbers",
- "test_add_remove_single_field_using_string_arguments",
- "test_create_table_with_custom_sequence_name",
- "test_add_remove_single_field_using_symbol_arguments",
- "_one_time_conditions_valid_14?",
- "_one_time_conditions_valid_16?",
- "run_callbacks",
- "anything",
- "silence_warnings",
- "instance_variable_names",
- "_fixture_path",
- "copy_instance_variables_from",
- "fixture_path?",
- "has_entry",
- "__marshal__",
- "_fixture_table_names",
- "__kind_of__",
- "fixture_table_names?",
- "test_add_rename",
- "assert_equal",
- "_fixture_class_names",
- "fixture_class_names?",
- "has_entries",
- "_use_transactional_fixtures",
- "people",
- "test_rename_column_using_symbol_arguments",
- "use_transactional_fixtures?",
- "instance_eval",
- "blank?",
- "with_warnings",
- "__nil__",
- "load",
- "metaclass",
- "_use_instantiated_fixtures",
- "has_key",
- "class_eval",
- "present?",
- "test_rename_column",
- "teardown",
- "use_instantiated_fixtures?",
- "method_name",
- "silence_stderr",
- "presence",
- "test_rename_column_preserves_default_value_not_null",
- "silence_stream",
- "_pre_loaded_fixtures",
- "__metaclass__",
- "__fixnum__",
- "pre_loaded_fixtures?",
- "has_value",
- "suppress",
- "to_yaml_properties",
- "test_rename_nonexistent_column",
- "test_add_index",
- "includes",
- "find_correlate_in",
- "equality_predicate_sql",
- "assert_nothing_raised",
- "let",
- "not_predicate_sql",
- "test_rename_column_with_sql_reserved_word",
- "singleton_class",
- "test_rename_column_with_an_index",
- "display",
- "taguri",
- "to_yaml_style",
- "test_remove_column_with_index",
- "size",
- "current_adapter?",
- "test_remove_column_with_multi_column_index",
- "respond_to?",
- "test_change_type_of_not_null_column",
- "is_a",
- "to_a",
- "test_rename_table_for_sqlite_should_work_with_reserved_words",
- "require_library_or_gem",
- "setup_fixtures",
- "equal?",
- "teardown_fixtures",
- "nil?",
- "fixture_table_names",
- "fixture_class_names",
- "test_create_table_without_id",
- "use_transactional_fixtures",
- "test_add_column_with_primary_key_attribute",
- "repair_validations",
- "use_instantiated_fixtures",
- "instance_of?",
- "test_create_table_adds_id",
- "test_rename_table",
- "pre_loaded_fixtures",
- "to_enum",
- "test_create_table_with_not_null_column",
- "instance_of",
- "test_change_column_nullability",
- "optionally",
- "test_rename_table_with_an_index",
- "run",
- "test_change_column",
- "default_test",
- "assert_raise",
- "test_create_table_with_defaults",
- "assert_nil",
- "flunk",
- "regexp_matches",
- "duplicable?",
- "reset_mocha",
- "stubba_method",
- "filter_backtrace",
- "test_create_table_with_limits",
- "responds_with",
- "stubba_object",
- "test_change_column_with_nil_default",
- "assert_block",
- "__show__",
- "assert_date_from_db",
- "__respond_to_eh__",
- "run_in_transaction?",
- "inspect",
- "assert_sql",
- "test_change_column_with_new_default",
- "yaml_equivalent",
- "build_message",
- "to_s",
- "test_change_column_default",
- "assert_queries",
- "pending",
- "as_json",
- "assert_no_queries",
- "test_change_column_quotes_column_names",
- "assert_match",
- "test_keeping_default_and_notnull_constraint_on_change",
- "methods",
- "connection_allow_concurrency_setup",
- "connection_allow_concurrency_teardown",
- "test_create_table_with_primary_key_prefix_as_table_name_with_underscore",
- "__send__",
- "make_connection",
- "assert_raises",
- "tap",
- "with_kcode",
- "assert_instance_of",
- "test_create_table_with_primary_key_prefix_as_table_name",
- "assert_respond_to",
- "test_change_column_default_to_null",
- "assert_same",
- "__extend__"]
-
-  LargeTestArraySorted = ["test_add_column_not_null_with_default",
- "test_add_column_with_precision_and_scale",
- "test_add_column_with_primary_key_attribute",
- "test_add_drop_table_with_prefix_and_suffix",
- "test_add_index",
- "test_add_remove_single_field_using_string_arguments",
- "test_add_remove_single_field_using_symbol_arguments",
- "test_add_rename",
- "test_add_table",
- "test_add_table_with_decimals",
- "test_change_column",
- "test_change_column_default",
- "test_change_column_default_to_null",
- "test_change_column_nullability",
- "test_change_column_quotes_column_names",
- "test_change_column_with_new_default",
- "test_change_column_with_nil_default",
- "test_change_type_of_not_null_column",
- "test_create_table_adds_id",
- "test_create_table_with_binary_column",
- "test_create_table_with_custom_sequence_name",
- "test_create_table_with_defaults",
- "test_create_table_with_force_true_does_not_drop_nonexisting_table",
- "test_create_table_with_limits",
- "test_create_table_with_not_null_column",
- "test_create_table_with_primary_key_prefix_as_table_name",
- "test_create_table_with_primary_key_prefix_as_table_name_with_underscore",
- "test_create_table_with_timestamps_should_create_datetime_columns",
- "test_create_table_with_timestamps_should_create_datetime_columns_with_options",
- "test_create_table_without_a_block",
- "test_create_table_without_id",
- "test_finds_migrations",
- "test_finds_pending_migrations",
- "test_keeping_default_and_notnull_constraint_on_change",
- "test_migrator",
- "test_migrator_db_has_no_schema_migrations_table",
- "test_migrator_double_down",
- "test_migrator_double_up",
- "test_migrator_forward",
- "test_migrator_going_down_due_to_version_target",
- "test_migrator_one_down",
- "test_migrator_one_up",
- "test_migrator_one_up_one_down",
- "test_migrator_one_up_with_exception_and_rollback",
- "test_migrator_rollback",
- "test_migrator_verbosity",
- "test_migrator_verbosity_off",
- "test_migrator_with_duplicate_names",
- "test_migrator_with_duplicates",
- "test_migrator_with_missing_version_numbers",
- "test_native_decimal_insert_manual_vs_automatic",
- "test_native_types",
- "test_only_loads_pending_migrations",
- "test_proper_table_name",
- "test_relative_migrations",
- "test_remove_column_with_index",
- "test_remove_column_with_multi_column_index",
- "test_rename_column",
- "test_rename_column_preserves_default_value_not_null",
- "test_rename_column_using_symbol_arguments",
- "test_rename_column_with_an_index",
- "test_rename_column_with_sql_reserved_word",
- "test_rename_nonexistent_column",
- "test_rename_table",
- "test_rename_table_for_sqlite_should_work_with_reserved_words",
- "test_rename_table_with_an_index",
- "test_schema_migrations_table_name",
- "test_target_version_zero_should_run_only_once"]
+  LargeArray = [
+    "test_create_table_with_force_true_does_not_drop_nonexisting_table",
+    "test_add_table",
+    "assert_difference",
+    "assert_operator",
+    "instance_variables",
+    "class",
+    "instance_variable_get",
+    "__class__",
+    "expects",
+    "assert_no_difference",
+    "name",
+    "assert_blank",
+    "assert_not_same",
+    "is_a?",
+    "test_add_table_with_decimals",
+    "test_create_table_with_timestamps_should_create_datetime_columns",
+    "assert_present",
+    "assert_no_match",
+    "__instance_of__",
+    "assert_deprecated",
+    "assert",
+    "assert_throws",
+    "kind_of?",
+    "try",
+    "__instance_variable_get__",
+    "object_id",
+    "timeout",
+    "instance_variable_set",
+    "assert_nothing_thrown",
+    "__instance_variable_set__",
+    "copy_object",
+    "test_create_table_with_timestamps_should_create_datetime_columns_with_options",
+    "assert_not_deprecated",
+    "assert_in_delta",
+    "id",
+    "copy_metaclass",
+    "test_create_table_without_a_block",
+    "dup",
+    "assert_not_nil",
+    "send",
+    "__instance_variables__",
+    "to_sql",
+    "mock",
+    "assert_send",
+    "instance_variable_defined?",
+    "clone",
+    "require",
+    "test_migrator",
+    "__instance_variable_defined_eh__",
+    "frozen?",
+    "test_add_column_not_null_with_default",
+    "freeze",
+    "test_migrator_one_up",
+    "test_migrator_one_down",
+    "singleton_methods",
+    "method_exists?",
+    "create_fixtures",
+    "test_migrator_one_up_one_down",
+    "test_native_decimal_insert_manual_vs_automatic",
+    "instance_exec",
+    "__is_a__",
+    "test_migrator_double_up",
+    "stub",
+    "private_methods",
+    "stubs",
+    "test_migrator_double_down",
+    "fixture_path",
+    "private_singleton_methods",
+    "stub_everything",
+    "test_migrator_one_up_with_exception_and_rollback",
+    "sequence",
+    "protected_methods",
+    "enum_for",
+    "test_finds_migrations",
+    "run_before_mocha",
+    "states",
+    "protected_singleton_methods",
+    "to_json",
+    "instance_values",
+    "==",
+    "mocha_setup",
+    "public_methods",
+    "test_finds_pending_migrations",
+    "mocha_verify",
+    "assert_kind_of",
+    "===",
+    "=~",
+    "test_relative_migrations",
+    "mocha_teardown",
+    "gem",
+    "mocha",
+    "test_only_loads_pending_migrations",
+    "test_add_column_with_precision_and_scale",
+    "require_or_load",
+    "eql?",
+    "require_dependency",
+    "test_native_types",
+    "test_target_version_zero_should_run_only_once",
+    "extend",
+    "to_matcher",
+    "unloadable",
+    "require_association",
+    "hash",
+    "__id__",
+    "load_dependency",
+    "equals",
+    "test_migrator_db_has_no_schema_migrations_table",
+    "test_migrator_verbosity",
+    "kind_of",
+    "to_yaml",
+    "to_bool",
+    "test_migrator_verbosity_off",
+    "taint",
+    "test_migrator_going_down_due_to_version_target",
+    "tainted?",
+    "mocha_inspect",
+    "test_migrator_rollback",
+    "vim",
+    "untaint",
+    "taguri=",
+    "test_migrator_forward",
+    "test_schema_migrations_table_name",
+    "test_proper_table_name",
+    "all_of",
+    "test_add_drop_table_with_prefix_and_suffix",
+    "_setup_callbacks",
+    "setup",
+    "Not",
+    "test_create_table_with_binary_column",
+    "assert_not_equal",
+    "enable_warnings",
+    "acts_like?",
+    "Rational",
+    "_removed_setup_callbacks",
+    "Table",
+    "bind",
+    "any_of",
+    "__method__",
+    "test_migrator_with_duplicates",
+    "_teardown_callbacks",
+    "method",
+    "test_migrator_with_duplicate_names",
+    "_removed_teardown_callbacks",
+    "any_parameters",
+    "test_migrator_with_missing_version_numbers",
+    "test_add_remove_single_field_using_string_arguments",
+    "test_create_table_with_custom_sequence_name",
+    "test_add_remove_single_field_using_symbol_arguments",
+    "_one_time_conditions_valid_14?",
+    "_one_time_conditions_valid_16?",
+    "run_callbacks",
+    "anything",
+    "silence_warnings",
+    "instance_variable_names",
+    "_fixture_path",
+    "copy_instance_variables_from",
+    "fixture_path?",
+    "has_entry",
+    "__marshal__",
+    "_fixture_table_names",
+    "__kind_of__",
+    "fixture_table_names?",
+    "test_add_rename",
+    "assert_equal",
+    "_fixture_class_names",
+    "fixture_class_names?",
+    "has_entries",
+    "_use_transactional_fixtures",
+    "people",
+    "test_rename_column_using_symbol_arguments",
+    "use_transactional_fixtures?",
+    "instance_eval",
+    "blank?",
+    "with_warnings",
+    "__nil__",
+    "load",
+    "metaclass",
+    "_use_instantiated_fixtures",
+    "has_key",
+    "class_eval",
+    "present?",
+    "test_rename_column",
+    "teardown",
+    "use_instantiated_fixtures?",
+    "method_name",
+    "silence_stderr",
+    "presence",
+    "test_rename_column_preserves_default_value_not_null",
+    "silence_stream",
+    "_pre_loaded_fixtures",
+    "__metaclass__",
+    "__fixnum__",
+    "pre_loaded_fixtures?",
+    "has_value",
+    "suppress",
+    "to_yaml_properties",
+    "test_rename_nonexistent_column",
+    "test_add_index",
+    "includes",
+    "find_correlate_in",
+    "equality_predicate_sql",
+    "assert_nothing_raised",
+    "let",
+    "not_predicate_sql",
+    "test_rename_column_with_sql_reserved_word",
+    "singleton_class",
+    "test_rename_column_with_an_index",
+    "display",
+    "taguri",
+    "to_yaml_style",
+    "test_remove_column_with_index",
+    "size",
+    "current_adapter?",
+    "test_remove_column_with_multi_column_index",
+    "respond_to?",
+    "test_change_type_of_not_null_column",
+    "is_a",
+    "to_a",
+    "test_rename_table_for_sqlite_should_work_with_reserved_words",
+    "require_library_or_gem",
+    "setup_fixtures",
+    "equal?",
+    "teardown_fixtures",
+    "nil?",
+    "fixture_table_names",
+    "fixture_class_names",
+    "test_create_table_without_id",
+    "use_transactional_fixtures",
+    "test_add_column_with_primary_key_attribute",
+    "repair_validations",
+    "use_instantiated_fixtures",
+    "instance_of?",
+    "test_create_table_adds_id",
+    "test_rename_table",
+    "pre_loaded_fixtures",
+    "to_enum",
+    "test_create_table_with_not_null_column",
+    "instance_of",
+    "test_change_column_nullability",
+    "optionally",
+    "test_rename_table_with_an_index",
+    "run",
+    "test_change_column",
+    "default_test",
+    "assert_raise",
+    "test_create_table_with_defaults",
+    "assert_nil",
+    "flunk",
+    "regexp_matches",
+    "duplicable?",
+    "reset_mocha",
+    "stubba_method",
+    "filter_backtrace",
+    "test_create_table_with_limits",
+    "responds_with",
+    "stubba_object",
+    "test_change_column_with_nil_default",
+    "assert_block",
+    "__show__",
+    "assert_date_from_db",
+    "__respond_to_eh__",
+    "run_in_transaction?",
+    "inspect",
+    "assert_sql",
+    "test_change_column_with_new_default",
+    "yaml_equivalent",
+    "build_message",
+    "to_s",
+    "test_change_column_default",
+    "assert_queries",
+    "pending",
+    "as_json",
+    "assert_no_queries",
+    "test_change_column_quotes_column_names",
+    "assert_match",
+    "test_keeping_default_and_notnull_constraint_on_change",
+    "methods",
+    "connection_allow_concurrency_setup",
+    "connection_allow_concurrency_teardown",
+    "test_create_table_with_primary_key_prefix_as_table_name_with_underscore",
+    "__send__",
+    "make_connection",
+    "assert_raises",
+    "tap",
+    "with_kcode",
+    "assert_instance_of",
+    "test_create_table_with_primary_key_prefix_as_table_name",
+    "assert_respond_to",
+    "test_change_column_default_to_null",
+    "assert_same",
+    "__extend__",
+  ]
+
+  LargeTestArraySorted = [
+    "test_add_column_not_null_with_default",
+    "test_add_column_with_precision_and_scale",
+    "test_add_column_with_primary_key_attribute",
+    "test_add_drop_table_with_prefix_and_suffix",
+    "test_add_index",
+    "test_add_remove_single_field_using_string_arguments",
+    "test_add_remove_single_field_using_symbol_arguments",
+    "test_add_rename",
+    "test_add_table",
+    "test_add_table_with_decimals",
+    "test_change_column",
+    "test_change_column_default",
+    "test_change_column_default_to_null",
+    "test_change_column_nullability",
+    "test_change_column_quotes_column_names",
+    "test_change_column_with_new_default",
+    "test_change_column_with_nil_default",
+    "test_change_type_of_not_null_column",
+    "test_create_table_adds_id",
+    "test_create_table_with_binary_column",
+    "test_create_table_with_custom_sequence_name",
+    "test_create_table_with_defaults",
+    "test_create_table_with_force_true_does_not_drop_nonexisting_table",
+    "test_create_table_with_limits",
+    "test_create_table_with_not_null_column",
+    "test_create_table_with_primary_key_prefix_as_table_name",
+    "test_create_table_with_primary_key_prefix_as_table_name_with_underscore",
+    "test_create_table_with_timestamps_should_create_datetime_columns",
+    "test_create_table_with_timestamps_should_create_datetime_columns_with_options",
+    "test_create_table_without_a_block",
+    "test_create_table_without_id",
+    "test_finds_migrations",
+    "test_finds_pending_migrations",
+    "test_keeping_default_and_notnull_constraint_on_change",
+    "test_migrator",
+    "test_migrator_db_has_no_schema_migrations_table",
+    "test_migrator_double_down",
+    "test_migrator_double_up",
+    "test_migrator_forward",
+    "test_migrator_going_down_due_to_version_target",
+    "test_migrator_one_down",
+    "test_migrator_one_up",
+    "test_migrator_one_up_one_down",
+    "test_migrator_one_up_with_exception_and_rollback",
+    "test_migrator_rollback",
+    "test_migrator_verbosity",
+    "test_migrator_verbosity_off",
+    "test_migrator_with_duplicate_names",
+    "test_migrator_with_duplicates",
+    "test_migrator_with_missing_version_numbers",
+    "test_native_decimal_insert_manual_vs_automatic",
+    "test_native_types",
+    "test_only_loads_pending_migrations",
+    "test_proper_table_name",
+    "test_relative_migrations",
+    "test_remove_column_with_index",
+    "test_remove_column_with_multi_column_index",
+    "test_rename_column",
+    "test_rename_column_preserves_default_value_not_null",
+    "test_rename_column_using_symbol_arguments",
+    "test_rename_column_with_an_index",
+    "test_rename_column_with_sql_reserved_word",
+    "test_rename_nonexistent_column",
+    "test_rename_table",
+    "test_rename_table_for_sqlite_should_work_with_reserved_words",
+    "test_rename_table_with_an_index",
+    "test_schema_migrations_table_name",
+    "test_target_version_zero_should_run_only_once",
+  ]
 
   class PrivateToAry
     private
diff --git a/spec/ruby/core/array/fixtures/encoded_strings.rb b/spec/ruby/core/array/fixtures/encoded_strings.rb
index 5b85bd0e06..b5888d86ae 100644
--- a/spec/ruby/core/array/fixtures/encoded_strings.rb
+++ b/spec/ruby/core/array/fixtures/encoded_strings.rb
@@ -2,14 +2,14 @@
 module ArraySpecs
   def self.array_with_usascii_and_7bit_utf8_strings
     [
-      'foo'.force_encoding('US-ASCII'),
+      'foo'.dup.force_encoding('US-ASCII'),
       'bar'
     ]
   end
 
   def self.array_with_usascii_and_utf8_strings
     [
-      'foo'.force_encoding('US-ASCII'),
+      'foo'.dup.force_encoding('US-ASCII'),
       'báz'
     ]
   end
@@ -17,7 +17,7 @@ module ArraySpecs
   def self.array_with_7bit_utf8_and_usascii_strings
     [
       'bar',
-      'foo'.force_encoding('US-ASCII')
+      'foo'.dup.force_encoding('US-ASCII')
     ]
   end
 
@@ -25,13 +25,13 @@ module ArraySpecs
     [
       'báz',
       'bar',
-      'foo'.force_encoding('US-ASCII')
+      'foo'.dup.force_encoding('US-ASCII')
     ]
   end
 
   def self.array_with_usascii_and_utf8_strings
     [
-      'foo'.force_encoding('US-ASCII'),
+      'foo'.dup.force_encoding('US-ASCII'),
       'bar',
       'báz'
     ]
@@ -41,7 +41,7 @@ module ArraySpecs
     [
       'bar',
       'báz',
-      'foo'.force_encoding('BINARY')
+      'foo'.dup.force_encoding('BINARY')
     ]
   end
 
@@ -55,14 +55,14 @@ module ArraySpecs
 
   def self.array_with_usascii_and_7bit_binary_strings
     [
-      'bar'.force_encoding('US-ASCII'),
-      'foo'.force_encoding('BINARY')
+      'bar'.dup.force_encoding('US-ASCII'),
+      'foo'.dup.force_encoding('BINARY')
     ]
   end
 
   def self.array_with_usascii_and_binary_strings
     [
-      'bar'.force_encoding('US-ASCII'),
+      'bar'.dup.force_encoding('US-ASCII'),
       [255].pack('C').force_encoding('BINARY')
     ]
   end
diff --git a/spec/ruby/core/array/flatten_spec.rb b/spec/ruby/core/array/flatten_spec.rb
index b506f899b4..272406b8f9 100644
--- a/spec/ruby/core/array/flatten_spec.rb
+++ b/spec/ruby/core/array/flatten_spec.rb
@@ -13,7 +13,7 @@ describe "Array#flatten" do
   it "returns dup when the level of recursion is 0" do
     a = [ 1, 2, [3, [4, 5] ] ]
     a.flatten(0).should == a
-    a.flatten(0).should_not equal(a)
+    a.flatten(0).should_not.equal?(a)
   end
 
   it "ignores negative levels" do
@@ -30,7 +30,7 @@ describe "Array#flatten" do
 
   it "raises a TypeError when the passed Object can't be converted to an Integer" do
     obj = mock("Not converted")
-    -> { [ 1, 2, [3, [4, 5] ] ].flatten(obj) }.should raise_error(TypeError)
+    -> { [ 1, 2, [3, [4, 5] ] ].flatten(obj) }.should.raise(TypeError)
   end
 
   it "does not call flatten on elements" do
@@ -46,13 +46,13 @@ describe "Array#flatten" do
   it "raises an ArgumentError on recursive arrays" do
     x = []
     x << x
-    -> { x.flatten }.should raise_error(ArgumentError)
+    -> { x.flatten }.should.raise(ArgumentError)
 
     x = []
     y = []
     x << y
     y << x
-    -> { x.flatten }.should raise_error(ArgumentError)
+    -> { x.flatten }.should.raise(ArgumentError)
   end
 
   it "flattens any element which responds to #to_ary, using the return value of said method" do
@@ -75,12 +75,12 @@ describe "Array#flatten" do
     [[obj]].flatten(1)
   end
 
-  it "returns subclass instance for Array subclasses" do
-    ArraySpecs::MyArray[].flatten.should be_an_instance_of(ArraySpecs::MyArray)
-    ArraySpecs::MyArray[1, 2, 3].flatten.should be_an_instance_of(ArraySpecs::MyArray)
-    ArraySpecs::MyArray[1, [2], 3].flatten.should be_an_instance_of(ArraySpecs::MyArray)
-    ArraySpecs::MyArray[1, [2, 3], 4].flatten.should == ArraySpecs::MyArray[1, 2, 3, 4]
-    [ArraySpecs::MyArray[1, 2, 3]].flatten.should be_an_instance_of(Array)
+  it "returns Array instance for Array subclasses" do
+    ArraySpecs::MyArray[].flatten.should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].flatten.should.instance_of?(Array)
+    ArraySpecs::MyArray[1, [2], 3].flatten.should.instance_of?(Array)
+    ArraySpecs::MyArray[1, [2, 3], 4].flatten.should == [1, 2, 3, 4]
+    [ArraySpecs::MyArray[1, 2, 3]].flatten.should.instance_of?(Array)
   end
 
   it "is not destructive" do
@@ -106,23 +106,13 @@ describe "Array#flatten" do
 
     it "raises a TypeError if #to_ary does not return an Array" do
       @obj.should_receive(:to_ary).and_return(1)
-      -> { [@obj].flatten }.should raise_error(TypeError)
+      -> { [@obj].flatten }.should.raise(TypeError)
     end
 
-    ruby_version_is ""..."2.5" do
-      it "calls respond_to_missing?(:to_ary, false) to try coercing" do
-        def @obj.respond_to_missing?(*args) ScratchPad << args; false end
-        [@obj].flatten.should == [@obj]
-        ScratchPad.recorded.should == [[:to_ary, false]]
-      end
-    end
-
-    ruby_version_is "2.5" do
-      it "calls respond_to_missing?(:to_ary, true) to try coercing" do
-        def @obj.respond_to_missing?(*args) ScratchPad << args; false end
-        [@obj].flatten.should == [@obj]
-        ScratchPad.recorded.should == [[:to_ary, true]]
-      end
+    it "calls respond_to_missing?(:to_ary, true) to try coercing" do
+      def @obj.respond_to_missing?(*args) ScratchPad << args; false end
+      [@obj].flatten.should == [@obj]
+      ScratchPad.recorded.should == [[:to_ary, true]]
     end
 
     it "does not call #to_ary if not defined when #respond_to_missing? returns false" do
@@ -135,7 +125,7 @@ describe "Array#flatten" do
     it "calls #to_ary if not defined when #respond_to_missing? returns true" do
       def @obj.respond_to_missing?(name, priv) ScratchPad << name; true end
 
-      -> { [@obj].flatten }.should raise_error(NoMethodError)
+      -> { [@obj].flatten }.should.raise(NoMethodError)
       ScratchPad.recorded.should == [:to_ary]
     end
 
@@ -145,14 +135,6 @@ describe "Array#flatten" do
     end
   end
 
-  it "returns a tainted array if self is tainted" do
-    [].taint.flatten.tainted?.should be_true
-  end
-
-  it "returns an untrusted array if self is untrusted" do
-    [].untrust.flatten.untrusted?.should be_true
-  end
-
   it "performs respond_to? and method_missing-aware checks when coercing elements to array" do
     bo = BasicObject.new
     [bo].flatten.should == [bo]
@@ -186,7 +168,7 @@ describe "Array#flatten!" do
 
   it "returns self if made some modifications" do
     a = [[[1, [2, 3]],[2, 3, [4, [4, [5, 5]], [1, 2, 3]]], [4]], []]
-    a.flatten!.should equal(a)
+    a.flatten!.should.equal?(a)
   end
 
   it "returns nil if no modifications took place" do
@@ -226,7 +208,7 @@ describe "Array#flatten!" do
 
   it "raises a TypeError when the passed Object can't be converted to an Integer" do
     obj = mock("Not converted")
-    -> { [ 1, 2, [3, [4, 5] ] ].flatten!(obj) }.should raise_error(TypeError)
+    -> { [ 1, 2, [3, [4, 5] ] ].flatten!(obj) }.should.raise(TypeError)
   end
 
   it "does not call flatten! on elements" do
@@ -242,13 +224,13 @@ describe "Array#flatten!" do
   it "raises an ArgumentError on recursive arrays" do
     x = []
     x << x
-    -> { x.flatten! }.should raise_error(ArgumentError)
+    -> { x.flatten! }.should.raise(ArgumentError)
 
     x = []
     y = []
     x << y
     y << x
-    -> { x.flatten! }.should raise_error(ArgumentError)
+    -> { x.flatten! }.should.raise(ArgumentError)
   end
 
   it "flattens any elements which responds to #to_ary, using the return value of said method" do
@@ -266,19 +248,19 @@ describe "Array#flatten!" do
 
     ary = [ArraySpecs::MyArray[1, 2, 3]]
     ary.flatten!
-    ary.should be_an_instance_of(Array)
+    ary.should.instance_of?(Array)
     ary.should == [1, 2, 3]
   end
 
-  it "raises a #{frozen_error_class} on frozen arrays when the array is modified" do
+  it "raises a FrozenError on frozen arrays when the array is modified" do
     nested_ary = [1, 2, []]
     nested_ary.freeze
-    -> { nested_ary.flatten! }.should raise_error(frozen_error_class)
+    -> { nested_ary.flatten! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23663]
-  it "raises a #{frozen_error_class} on frozen arrays when the array would not be modified" do
-    -> { ArraySpecs.frozen_array.flatten! }.should raise_error(frozen_error_class)
-    -> { ArraySpecs.empty_frozen_array.flatten! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on frozen arrays when the array would not be modified" do
+    -> { ArraySpecs.frozen_array.flatten! }.should.raise(FrozenError)
+    -> { ArraySpecs.empty_frozen_array.flatten! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/frozen_spec.rb b/spec/ruby/core/array/frozen_spec.rb
index bb4b2b4067..3ba54be46b 100644
--- a/spec/ruby/core/array/frozen_spec.rb
+++ b/spec/ruby/core/array/frozen_spec.rb
@@ -4,13 +4,13 @@ require_relative 'fixtures/classes'
 describe "Array#frozen?" do
   it "returns true if array is frozen" do
     a = [1, 2, 3]
-    a.frozen?.should == false
+    a.should_not.frozen?
     a.freeze
-    a.frozen?.should == true
+    a.should.frozen?
   end
 
   it "returns false for an array being sorted by #sort" do
     a = [1, 2, 3]
-    a.sort { |x,y| a.frozen?.should == false; x <=> y }
+    a.sort { |x,y| a.should_not.frozen?; x <=> y }
   end
 end
diff --git a/spec/ruby/core/array/hash_spec.rb b/spec/ruby/core/array/hash_spec.rb
index 8392253ae4..3b7b6d5bed 100644
--- a/spec/ruby/core/array/hash_spec.rb
+++ b/spec/ruby/core/array/hash_spec.rb
@@ -7,16 +7,16 @@ describe "Array#hash" do
 
     [[], [1, 2, 3]].each do |ary|
       ary.hash.should == ary.dup.hash
-      ary.hash.should be_an_instance_of(Fixnum)
+      ary.hash.should.instance_of?(Integer)
     end
   end
 
   it "properly handles recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
-    -> { empty.hash }.should_not raise_error
+    -> { empty.hash }.should_not.raise
 
     array = ArraySpecs.recursive_array
-    -> { array.hash }.should_not raise_error
+    -> { array.hash }.should_not.raise
   end
 
   it "returns the same hash for equal recursive arrays" do
@@ -74,7 +74,7 @@ describe "Array#hash" do
     a.fill 'a', 0..3
     b = %w|a a a a|
     a.hash.should == b.hash
-    a.should eql(b)
+    a.should.eql?(b)
   end
 
   it "produces different hashes for nested arrays with different values and empty terminator" do
diff --git a/spec/ruby/core/array/index_spec.rb b/spec/ruby/core/array/index_spec.rb
index 3acb7d0ef3..b66cb6eb53 100644
--- a/spec/ruby/core/array/index_spec.rb
+++ b/spec/ruby/core/array/index_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/index'
 
 describe "Array#index" do
-  it_behaves_like :array_index, :index
+  it "is an alias of Array#find_index" do
+    Array.instance_method(:index).should == Array.instance_method(:find_index)
+  end
 end
diff --git a/spec/ruby/core/array/initialize_spec.rb b/spec/ruby/core/array/initialize_spec.rb
index dfc2ae3518..19ee37825e 100644
--- a/spec/ruby/core/array/initialize_spec.rb
+++ b/spec/ruby/core/array/initialize_spec.rb
@@ -7,7 +7,7 @@ describe "Array#initialize" do
   end
 
   it "is private" do
-    Array.should have_private_instance_method("initialize")
+    Array.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "is called on subclasses" do
@@ -19,26 +19,26 @@ describe "Array#initialize" do
 
   it "preserves the object's identity even when changing its value" do
     a = [1, 2, 3]
-    a.send(:initialize).should equal(a)
+    a.send(:initialize).should.equal?(a)
     a.should_not == [1, 2, 3]
   end
 
   it "raises an ArgumentError if passed 3 or more arguments" do
     -> do
       [1, 2].send :initialize, 1, 'x', true
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       [1, 2].send(:initialize, 1, 'x', true) {}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
-  it "raises a #{frozen_error_class} on frozen arrays" do
+  it "raises a FrozenError on frozen arrays" do
     -> do
       ArraySpecs.frozen_array.send :initialize
-    end.should raise_error(frozen_error_class)
+    end.should.raise(FrozenError)
     -> do
       ArraySpecs.frozen_array.send :initialize, ArraySpecs.frozen_array
-    end.should raise_error(frozen_error_class)
+    end.should.raise(FrozenError)
   end
 
   it "calls #to_ary to convert the value to an array, even if it's private" do
@@ -49,11 +49,13 @@ end
 
 describe "Array#initialize with no arguments" do
   it "makes the array empty" do
-    [1, 2, 3].send(:initialize).should be_empty
+    [1, 2, 3].send(:initialize).should.empty?
   end
 
   it "does not use the given block" do
-    ->{ [1, 2, 3].send(:initialize) { raise } }.should_not raise_error
+    -> {
+      -> { [1, 2, 3].send(:initialize) { raise } }.should_not.raise
+    }.should complain(/#{__FILE__}:#{__LINE__-1}: warning: given block not used/, verbose: true)
   end
 end
 
@@ -64,7 +66,7 @@ describe "Array#initialize with (array)" do
   end
 
   it "does not use the given block" do
-    ->{ [1, 2, 3].send(:initialize) { raise } }.should_not raise_error
+    ->{ [1, 2, 3].send(:initialize) { raise } }.should_not.raise
   end
 
   it "calls #to_ary to convert the value to an array" do
@@ -81,7 +83,7 @@ describe "Array#initialize with (array)" do
   end
 
   it "raises a TypeError if an Array type argument and a default object" do
-    -> { [].send(:initialize, [1, 2], 1) }.should raise_error(TypeError)
+    -> { [].send(:initialize, [1, 2], 1) }.should.raise(TypeError)
   end
 end
 
@@ -90,8 +92,8 @@ describe "Array#initialize with (size, object=nil)" do
     a = []
     obj = [3]
     a.send(:initialize, 2, obj).should == [obj, obj]
-    a[0].should equal(obj)
-    a[1].should equal(obj)
+    a[0].should.equal?(obj)
+    a[1].should.equal?(obj)
 
     b = []
     b.send(:initialize, 3, 14).should == [14, 14, 14]
@@ -103,12 +105,12 @@ describe "Array#initialize with (size, object=nil)" do
   end
 
   it "raises an ArgumentError if size is negative" do
-    -> { [].send(:initialize, -1, :a) }.should raise_error(ArgumentError)
-    -> { [].send(:initialize, -1) }.should raise_error(ArgumentError)
+    -> { [].send(:initialize, -1, :a) }.should.raise(ArgumentError)
+    -> { [].send(:initialize, -1) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if size is too large" do
-    -> { [].send(:initialize, fixnum_max+1) }.should raise_error(ArgumentError)
+    -> { [].send(:initialize, fixnum_max+1) }.should.raise(ArgumentError)
   end
 
   it "calls #to_int to convert the size argument to an Integer when object is given" do
@@ -126,7 +128,7 @@ describe "Array#initialize with (size, object=nil)" do
   it "raises a TypeError if the size argument is not an Integer type" do
     obj = mock('nonnumeric')
     obj.stub!(:to_ary).and_return([1, 2])
-    ->{ [].send(:initialize, obj, :a) }.should raise_error(TypeError)
+    ->{ [].send(:initialize, obj, :a) }.should.raise(TypeError)
   end
 
   it "yields the index of the element and sets the element to the value of the block" do
diff --git a/spec/ruby/core/array/insert_spec.rb b/spec/ruby/core/array/insert_spec.rb
index 7577a8f743..38e132fd25 100644
--- a/spec/ruby/core/array/insert_spec.rb
+++ b/spec/ruby/core/array/insert_spec.rb
@@ -4,8 +4,8 @@ require_relative 'fixtures/classes'
 describe "Array#insert" do
   it "returns self" do
     ary = []
-    ary.insert(0).should equal(ary)
-    ary.insert(0, :a).should equal(ary)
+    ary.insert(0).should.equal?(ary)
+    ary.insert(0, :a).should.equal?(ary)
   end
 
   it "inserts objects before the element at index for non-negative index" do
@@ -46,8 +46,8 @@ describe "Array#insert" do
   end
 
   it "raises an IndexError if the negative index is out of bounds" do
-    -> { [].insert(-2, 1)  }.should raise_error(IndexError)
-    -> { [1].insert(-3, 2) }.should raise_error(IndexError)
+    -> { [].insert(-2, 1)  }.should.raise(IndexError)
+    -> { [1].insert(-3, 2) }.should.raise(IndexError)
   end
 
   it "does nothing of no object is passed" do
@@ -64,15 +64,15 @@ describe "Array#insert" do
   end
 
   it "raises an ArgumentError if no argument passed" do
-    -> { [].insert() }.should raise_error(ArgumentError)
+    -> { [].insert() }.should.raise(ArgumentError)
   end
 
-  it "raises a #{frozen_error_class} on frozen arrays when the array is modified" do
-    -> { ArraySpecs.frozen_array.insert(0, 'x') }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on frozen arrays when the array is modified" do
+    -> { ArraySpecs.frozen_array.insert(0, 'x') }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on frozen arrays when the array would not be modified" do
-    -> { ArraySpecs.frozen_array.insert(0) }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on frozen arrays when the array would not be modified" do
+    -> { ArraySpecs.frozen_array.insert(0) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/inspect_spec.rb b/spec/ruby/core/array/inspect_spec.rb
index 0832224f5a..e5dca82889 100644
--- a/spec/ruby/core/array/inspect_spec.rb
+++ b/spec/ruby/core/array/inspect_spec.rb
@@ -1,7 +1,108 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/inspect'
 
 describe "Array#inspect" do
-  it_behaves_like :array_inspect, :inspect
+  it "returns a string" do
+    [1, 2, 3].inspect.should.instance_of?(String)
+  end
+
+  it "returns '[]' for an empty Array" do
+    [].inspect.should == "[]"
+  end
+
+  it "calls inspect on its elements and joins the results with commas" do
+    items = Array.new(3) do |i|
+      obj = mock(i.to_s)
+      obj.should_receive(:inspect).and_return(i.to_s)
+      obj
+    end
+    items.inspect.should == "[0, 1, 2]"
+  end
+
+  it "does not call #to_s on a String returned from #inspect" do
+    str = +"abc"
+    str.should_not_receive(:to_s)
+
+    [str].inspect.should == '["abc"]'
+  end
+
+  it "calls #to_s on the object returned from #inspect if the Object isn't a String" do
+    obj = mock("Array#inspect/to_s calls #to_s")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_return("abc")
+
+    [obj].inspect.should == "[abc]"
+  end
+
+  it "does not call #to_str on the object returned from #inspect when it is not a String" do
+    obj = mock("Array#inspect/to_s does not call #to_str")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_not_receive(:to_str)
+
+    [obj].inspect.should =~ /^\[#<MockObject:0x[0-9a-f]+>\]$/
+  end
+
+  it "does not call #to_str on the object returned from #to_s when it is not a String" do
+    obj = mock("Array#inspect/to_s does not call #to_str on #to_s result")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_return(obj)
+    obj.should_not_receive(:to_str)
+
+    [obj].inspect.should =~ /^\[#<MockObject:0x[0-9a-f]+>\]$/
+  end
+
+  it "does not swallow exceptions raised by #to_s" do
+    obj = mock("Array#inspect/to_s does not swallow #to_s exceptions")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_raise(Exception)
+
+    -> { [obj].inspect }.should.raise(Exception)
+  end
+
+  it "represents a recursive element with '[...]'" do
+    ArraySpecs.recursive_array.inspect.should == "[1, \"two\", 3.0, [...], [...], [...], [...], [...]]"
+    ArraySpecs.head_recursive_array.inspect.should == "[[...], [...], [...], [...], [...], 1, \"two\", 3.0]"
+    ArraySpecs.empty_recursive_array.inspect.should == "[[...]]"
+  end
+
+  describe "with encoding" do
+    before :each do
+      @default_external_encoding = Encoding.default_external
+    end
+
+    after :each do
+      Encoding.default_external = @default_external_encoding
+    end
+
+    it "returns a US-ASCII string for an empty Array" do
+      [].inspect.encoding.should == Encoding::US_ASCII
+    end
+
+    it "use the default external encoding if it is ascii compatible" do
+      Encoding.default_external = Encoding.find('UTF-8')
+
+      utf8 = "utf8".encode("UTF-8")
+      jp   = "jp".encode("EUC-JP")
+      array = [jp, utf8]
+
+      array.inspect.encoding.name.should == "UTF-8"
+    end
+
+    it "use US-ASCII encoding if the default external encoding is not ascii compatible" do
+      Encoding.default_external = Encoding.find('UTF-32')
+
+      utf8 = "utf8".encode("UTF-8")
+      jp   = "jp".encode("EUC-JP")
+      array = [jp, utf8]
+
+      array.inspect.encoding.name.should == "US-ASCII"
+    end
+
+    it "does not raise if inspected result is not default external encoding" do
+      utf_16be = mock(+"utf_16be")
+      utf_16be.should_receive(:inspect).and_return(%<"utf_16be \u3042">.encode(Encoding::UTF_16BE))
+
+      [utf_16be].inspect.should == '["utf_16be \u3042"]'
+    end
+  end
 end
diff --git a/spec/ruby/core/array/intersect_spec.rb b/spec/ruby/core/array/intersect_spec.rb
new file mode 100644
index 0000000000..456aa26c6e
--- /dev/null
+++ b/spec/ruby/core/array/intersect_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe 'Array#intersect?' do
+  describe 'when at least one element in two Arrays is the same' do
+    it 'returns true' do
+      [1, 2].intersect?([2, 3, 4]).should == true
+      [2, 3, 4].intersect?([1, 2]).should == true
+    end
+  end
+
+  describe 'when there are no elements in common between two Arrays' do
+    it 'returns false' do
+      [0, 1, 2].intersect?([3, 4]).should == false
+      [3, 4].intersect?([0, 1, 2]).should == false
+      [3, 4].intersect?([]).should == false
+      [].intersect?([0, 1, 2]).should == false
+    end
+  end
+
+  it "tries to convert the passed argument to an Array using #to_ary" do
+    obj = mock('[1,2,3]')
+    obj.should_receive(:to_ary).and_return([1, 2, 3])
+
+    [1, 2].intersect?(obj).should == true
+  end
+
+  it "determines equivalence between elements in the sense of eql?" do
+    obj1 = mock('1')
+    obj2 = mock('2')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.stub!(:eql?).and_return(true)
+    obj2.stub!(:eql?).and_return(true)
+
+    [obj1].intersect?([obj2]).should == true
+
+    obj1 = mock('3')
+    obj2 = mock('4')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.stub!(:eql?).and_return(false)
+    obj2.stub!(:eql?).and_return(false)
+
+    [obj1].intersect?([obj2]).should == false
+  end
+
+  it "does not call to_ary on array subclasses" do
+    [5, 6].intersect?(ArraySpecs::ToAryArray[1, 2, 5, 6]).should == true
+  end
+
+  it "properly handles an identical item even when its #eql? isn't reflexive" do
+    x = mock('x')
+    x.stub!(:hash).and_return(42)
+    x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
+
+    [x].intersect?([x]).should == true
+  end
+
+  it "has semantic of !(a & b).empty?" do
+    [].intersect?([]).should == false
+    [nil].intersect?([nil]).should == true
+  end
+end
diff --git a/spec/ruby/core/array/intersection_spec.rb b/spec/ruby/core/array/intersection_spec.rb
index 7bf2ec4dbe..e01a68d389 100644
--- a/spec/ruby/core/array/intersection_spec.rb
+++ b/spec/ruby/core/array/intersection_spec.rb
@@ -1,87 +1,19 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/intersection'
 
 describe "Array#&" do
-  it "creates an array with elements common to both arrays (intersection)" do
-    ([] & []).should == []
-    ([1, 2] & []).should == []
-    ([] & [1, 2]).should == []
-    ([ 1, 3, 5 ] & [ 1, 2, 3 ]).should == [1, 3]
-  end
-
-  it "creates an array with no duplicates" do
-    ([ 1, 1, 3, 5 ] & [ 1, 2, 3 ]).uniq!.should == nil
-  end
-
-  it "creates an array with elements in order they are first encountered" do
-    ([ 1, 2, 3, 2, 5 ] & [ 5, 2, 3, 4 ]).should == [2, 3, 5]
-  end
-
-  it "does not modify the original Array" do
-    a = [1, 1, 3, 5]
-    (a & [1, 2, 3]).should == [1, 3]
-    a.should == [1, 1, 3, 5]
-  end
-
-  it "properly handles recursive arrays" do
-    empty = ArraySpecs.empty_recursive_array
-    (empty & empty).should == empty
-
-    (ArraySpecs.recursive_array & []).should == []
-    ([] & ArraySpecs.recursive_array).should == []
-
-    (ArraySpecs.recursive_array & ArraySpecs.recursive_array).should == [1, 'two', 3.0, ArraySpecs.recursive_array]
-  end
-
-  it "tries to convert the passed argument to an Array using #to_ary" do
-    obj = mock('[1,2,3]')
-    obj.should_receive(:to_ary).and_return([1, 2, 3])
-    ([1, 2] & obj).should == ([1, 2])
-  end
-
-  it "determines equivalence between elements in the sense of eql?" do
-    not_supported_on :opal do
-      ([5.0, 4.0] & [5, 4]).should == []
-    end
-
-    str = "x"
-    ([str] & [str.dup]).should == [str]
-
-    obj1 = mock('1')
-    obj2 = mock('2')
-    obj1.stub!(:hash).and_return(0)
-    obj2.stub!(:hash).and_return(0)
-    obj1.should_receive(:eql?).at_least(1).and_return(true)
-    obj2.stub!(:eql?).and_return(true)
-
-    ([obj1] & [obj2]).should == [obj1]
-    ([obj1, obj1, obj2, obj2] & [obj2]).should == [obj1]
-
-    obj1 = mock('3')
-    obj2 = mock('4')
-    obj1.stub!(:hash).and_return(0)
-    obj2.stub!(:hash).and_return(0)
-    obj1.should_receive(:eql?).at_least(1).and_return(false)
+  it_behaves_like :array_intersection, :&
+end
 
-    ([obj1] & [obj2]).should == []
-    ([obj1, obj1, obj2, obj2] & [obj2]).should == [obj2]
-  end
+describe "Array#intersection" do
+  it_behaves_like :array_intersection, :intersection
 
-  it "does return subclass instances for Array subclasses" do
-    (ArraySpecs::MyArray[1, 2, 3] & []).should be_an_instance_of(Array)
-    (ArraySpecs::MyArray[1, 2, 3] & ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
-    ([] & ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
+  it "accepts multiple arguments" do
+    [1, 2, 3, 4].intersection([1, 2, 3], [2, 3, 4]).should == [2, 3]
   end
 
-  it "does not call to_ary on array subclasses" do
-    ([5, 6] & ArraySpecs::ToAryArray[1, 2, 5, 6]).should == [5, 6]
-  end
-
-  it "properly handles an identical item even when its #eql? isn't reflexive" do
-    x = mock('x')
-    x.stub!(:hash).and_return(42)
-    x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
-
-    ([x] & [x]).should == [x]
+  it "preserves elements order from original array" do
+    [1, 2, 3, 4].intersection([3, 2, 1]).should == [1, 2, 3]
   end
 end
diff --git a/spec/ruby/core/array/join_spec.rb b/spec/ruby/core/array/join_spec.rb
index e78ea6f9e1..3b4946a99f 100644
--- a/spec/ruby/core/array/join_spec.rb
+++ b/spec/ruby/core/array/join_spec.rb
@@ -4,7 +4,6 @@ require_relative 'shared/join'
 
 describe "Array#join" do
   it_behaves_like :array_join_with_string_separator,  :join
-  it_behaves_like :array_join_with_default_separator, :join
 
   it "does not separate elements when the passed separator is nil" do
     [1, 2, 3].join(nil).should == '123'
@@ -24,11 +23,108 @@ describe "Array#join" do
 
   it "raises a TypeError if the separator cannot be coerced to a String by calling #to_str" do
     obj = mock("not a string")
-    -> { [1, 2].join(obj) }.should raise_error(TypeError)
+    -> { [1, 2].join(obj) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false as the separator" do
-    -> { [1, 2].join(false) }.should raise_error(TypeError)
+    -> { [1, 2].join(false) }.should.raise(TypeError)
+  end
+end
+
+describe "Array#join with default separator" do
+  before :each do
+    @separator = $,
+  end
+
+  after :each do
+    $, = @separator
+  end
+
+  it "returns an empty string if the Array is empty" do
+    [].join.should == ''
+  end
+
+  it "returns a US-ASCII string for an empty Array" do
+    [].join.encoding.should == Encoding::US_ASCII
+  end
+
+  it "returns a string formed by concatenating each String element separated by $," do
+    suppress_warning {
+      $, = " | "
+      ["1", "2", "3"].join.should == "1 | 2 | 3"
+    }
+  end
+
+  it "attempts coercion via #to_str first" do
+    obj = mock('foo')
+    obj.should_receive(:to_str).any_number_of_times.and_return("foo")
+    [obj].join.should == "foo"
+  end
+
+  it "attempts coercion via #to_ary second" do
+    obj = mock('foo')
+    obj.should_receive(:to_str).any_number_of_times.and_return(nil)
+    obj.should_receive(:to_ary).any_number_of_times.and_return(["foo"])
+    [obj].join.should == "foo"
+  end
+
+  it "attempts coercion via #to_s third" do
+    obj = mock('foo')
+    obj.should_receive(:to_str).any_number_of_times.and_return(nil)
+    obj.should_receive(:to_ary).any_number_of_times.and_return(nil)
+    obj.should_receive(:to_s).any_number_of_times.and_return("foo")
+    [obj].join.should == "foo"
+  end
+
+  it "raises a NoMethodError if an element does not respond to #to_str, #to_ary, or #to_s" do
+    obj = mock('o')
+    class << obj; undef :to_s; end
+    -> { [1, obj].join }.should.raise(NoMethodError)
+  end
+
+  it "raises an ArgumentError when the Array is recursive" do
+    -> { ArraySpecs.recursive_array.join }.should.raise(ArgumentError)
+    -> { ArraySpecs.head_recursive_array.join }.should.raise(ArgumentError)
+    -> { ArraySpecs.empty_recursive_array.join }.should.raise(ArgumentError)
+  end
+
+  it "uses the first encoding when other strings are compatible" do
+    ary1 = ArraySpecs.array_with_7bit_utf8_and_usascii_strings
+    ary2 = ArraySpecs.array_with_usascii_and_7bit_utf8_strings
+    ary3 = ArraySpecs.array_with_utf8_and_7bit_binary_strings
+    ary4 = ArraySpecs.array_with_usascii_and_7bit_binary_strings
+
+    ary1.join.encoding.should == Encoding::UTF_8
+    ary2.join.encoding.should == Encoding::US_ASCII
+    ary3.join.encoding.should == Encoding::UTF_8
+    ary4.join.encoding.should == Encoding::US_ASCII
+  end
+
+  it "uses the widest common encoding when other strings are incompatible" do
+    ary1 = ArraySpecs.array_with_utf8_and_usascii_strings
+    ary2 = ArraySpecs.array_with_usascii_and_utf8_strings
+
+    ary1.join.encoding.should == Encoding::UTF_8
+    ary2.join.encoding.should == Encoding::UTF_8
+  end
+
+  it "fails for arrays with incompatibly-encoded strings" do
+    ary_utf8_bad_binary = ArraySpecs.array_with_utf8_and_binary_strings
+
+    -> { ary_utf8_bad_binary.join }.should.raise(EncodingError)
+  end
+
+  context "when $, is not nil" do
+    before do
+      suppress_warning do
+        $, = '*'
+      end
+    end
+
+    it "warns" do
+      -> { [].join }.should complain(/warning: \$, is set to non-nil value/)
+      -> { [].join(nil) }.should complain(/warning: \$, is set to non-nil value/)
+    end
   end
 end
 
diff --git a/spec/ruby/core/array/keep_if_spec.rb b/spec/ruby/core/array/keep_if_spec.rb
index bf2bdeaf91..62a65a04e8 100644
--- a/spec/ruby/core/array/keep_if_spec.rb
+++ b/spec/ruby/core/array/keep_if_spec.rb
@@ -1,9 +1,10 @@
+require_relative '../../spec_helper'
 require_relative 'shared/keep_if'
 
 describe "Array#keep_if" do
   it "returns the same array if no changes were made" do
     array = [1, 2, 3]
-    array.keep_if { true }.should equal(array)
+    array.keep_if { true }.should.equal?(array)
   end
 
   it_behaves_like :keep_if, :keep_if
diff --git a/spec/ruby/core/array/last_spec.rb b/spec/ruby/core/array/last_spec.rb
index d6fefada09..ed417bcd2a 100644
--- a/spec/ruby/core/array/last_spec.rb
+++ b/spec/ruby/core/array/last_spec.rb
@@ -28,7 +28,7 @@ describe "Array#last" do
   end
 
   it "raises an ArgumentError when count is negative" do
-    -> { [1, 2].last(-1) }.should raise_error(ArgumentError)
+    -> { [1, 2].last(-1) }.should.raise(ArgumentError)
   end
 
   it "returns the entire array when count > length" do
@@ -47,10 +47,10 @@ describe "Array#last" do
 
   it "properly handles recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
-    empty.last.should equal(empty)
+    empty.last.should.equal?(empty)
 
     array = ArraySpecs.recursive_array
-    array.last.should equal(array)
+    array.last.should.equal?(array)
   end
 
   it "tries to convert the passed argument to an Integer using #to_int" do
@@ -60,19 +60,19 @@ describe "Array#last" do
   end
 
   it "raises a TypeError if the passed argument is not numeric" do
-    -> { [1,2].last(nil) }.should raise_error(TypeError)
-    -> { [1,2].last("a") }.should raise_error(TypeError)
+    -> { [1,2].last(nil) }.should.raise(TypeError)
+    -> { [1,2].last("a") }.should.raise(TypeError)
 
     obj = mock("nonnumeric")
-    -> { [1,2].last(obj) }.should raise_error(TypeError)
+    -> { [1,2].last(obj) }.should.raise(TypeError)
   end
 
   it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[].last(0).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[].last(2).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].last(0).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].last(1).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].last(2).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[].last(0).should.instance_of?(Array)
+    ArraySpecs::MyArray[].last(2).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].last(0).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].last(1).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].last(2).should.instance_of?(Array)
   end
 
   it "is not destructive" do
diff --git a/spec/ruby/core/array/length_spec.rb b/spec/ruby/core/array/length_spec.rb
index a90c001300..74b2eb3a08 100644
--- a/spec/ruby/core/array/length_spec.rb
+++ b/spec/ruby/core/array/length_spec.rb
@@ -1,7 +1,14 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/length'
 
 describe "Array#length" do
-  it_behaves_like :array_length, :length
+  it "returns the number of elements" do
+    [].length.should == 0
+    [1, 2, 3].length.should == 3
+  end
+
+  it "properly handles recursive arrays" do
+    ArraySpecs.empty_recursive_array.length.should == 1
+    ArraySpecs.recursive_array.length.should == 8
+  end
 end
diff --git a/spec/ruby/core/array/map_spec.rb b/spec/ruby/core/array/map_spec.rb
index 0c7f3afa8c..f5e88c8624 100644
--- a/spec/ruby/core/array/map_spec.rb
+++ b/spec/ruby/core/array/map_spec.rb
@@ -1,11 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/collect'
 
 describe "Array#map" do
-  it_behaves_like :array_collect, :map
+  it "is an alias of Array#collect" do
+    Array.instance_method(:map).should == Array.instance_method(:collect)
+  end
 end
 
 describe "Array#map!" do
-  it_behaves_like :array_collect_b, :map!
+  it "is an alias of Array#collect!" do
+    Array.instance_method(:map!).should == Array.instance_method(:collect!)
+  end
 end
diff --git a/spec/ruby/core/array/max_spec.rb b/spec/ruby/core/array/max_spec.rb
index d1c64519d0..868275a748 100644
--- a/spec/ruby/core/array/max_spec.rb
+++ b/spec/ruby/core/array/max_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Array#max" do
   it "is defined on Array" do
-    [1].method(:max).owner.should equal Array
+    [1].method(:max).owner.should.equal? Array
   end
 
   it "returns nil with no values" do
@@ -70,16 +70,16 @@ describe "Array#max" do
   it "raises a NoMethodError for elements without #<=>" do
     -> do
       [BasicObject.new, BasicObject.new].max
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "raises an ArgumentError for incomparable elements" do
     -> do
       [11,"22"].max
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       [11,12,22,33].max{|a, b| nil}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "returns the maximum element (with block)" do
diff --git a/spec/ruby/core/array/min_spec.rb b/spec/ruby/core/array/min_spec.rb
index 3bdef0dd00..5913e08cf8 100644
--- a/spec/ruby/core/array/min_spec.rb
+++ b/spec/ruby/core/array/min_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Array#min" do
   it "is defined on Array" do
-    [1].method(:max).owner.should equal Array
+    [1].method(:max).owner.should.equal? Array
   end
 
   it "returns nil with no values" do
@@ -64,22 +64,22 @@ describe "Array#min" do
   end
 
   it "returns nil for an empty Enumerable" do
-    [].min.should be_nil
+    [].min.should == nil
   end
 
   it "raises a NoMethodError for elements without #<=>" do
     -> do
       [BasicObject.new, BasicObject.new].min
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "raises an ArgumentError for incomparable elements" do
     -> do
       [11,"22"].min
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       [11,12,22,33].min{|a, b| nil}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "returns the minimum when using a block rule" do
diff --git a/spec/ruby/core/array/minmax_spec.rb b/spec/ruby/core/array/minmax_spec.rb
new file mode 100644
index 0000000000..e11fe63347
--- /dev/null
+++ b/spec/ruby/core/array/minmax_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/enumerable/minmax'
+
+describe "Array#minmax" do
+  before :each do
+    @enum = [6, 4, 5, 10, 8]
+    @empty_enum = []
+    @incomparable_enum = [BasicObject.new, BasicObject.new]
+    @incompatible_enum = [11, "22"]
+    @strs = ["333", "2", "60", "55555", "1010", "111"]
+  end
+
+  it_behaves_like :enumerable_minmax, :minmax
+end
diff --git a/spec/ruby/core/array/multiply_spec.rb b/spec/ruby/core/array/multiply_spec.rb
index ab654ce489..1ac14e1b09 100644
--- a/spec/ruby/core/array/multiply_spec.rb
+++ b/spec/ruby/core/array/multiply_spec.rb
@@ -17,7 +17,7 @@ describe "Array#*" do
 
   it "raises a TypeError if the argument can neither be converted to a string nor an integer" do
     obj = mock('not a string or integer')
-    ->{ [1,2] * obj }.should raise_error(TypeError)
+    ->{ [1,2] * obj }.should.raise(TypeError)
   end
 
   it "converts the passed argument to a String rather than an Integer" do
@@ -28,15 +28,15 @@ describe "Array#*" do
   end
 
   it "raises a TypeError is the passed argument is nil" do
-    ->{ [1,2] * nil }.should raise_error(TypeError)
+    ->{ [1,2] * nil }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when passed 2 or more arguments" do
-    ->{ [1,2].send(:*, 1, 2) }.should raise_error(ArgumentError)
+    ->{ [1,2].send(:*, 1, 2) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when passed no arguments" do
-    ->{ [1,2].send(:*) }.should raise_error(ArgumentError)
+    ->{ [1,2].send(:*) }.should.raise(ArgumentError)
   end
 end
 
@@ -50,7 +50,7 @@ describe "Array#* with an integer" do
 
   it "does not return self even if the passed integer is 1" do
     ary = [1, 2, 3]
-    (ary * 1).should_not equal(ary)
+    (ary * 1).should_not.equal?(ary)
   end
 
   it "properly handles recursive arrays" do
@@ -65,8 +65,8 @@ describe "Array#* with an integer" do
   end
 
   it "raises an ArgumentError when passed a negative integer" do
-    -> { [ 1, 2, 3 ] * -1 }.should raise_error(ArgumentError)
-    -> { [] * -1 }.should raise_error(ArgumentError)
+    -> { [ 1, 2, 3 ] * -1 }.should.raise(ArgumentError)
+    -> { [] * -1 }.should.raise(ArgumentError)
   end
 
   describe "with a subclass of Array" do
@@ -76,55 +76,17 @@ describe "Array#* with an integer" do
       @array = ArraySpecs::MyArray[1, 2, 3, 4, 5]
     end
 
-    it "returns a subclass instance" do
-      (@array * 0).should be_an_instance_of(ArraySpecs::MyArray)
-      (@array * 1).should be_an_instance_of(ArraySpecs::MyArray)
-      (@array * 2).should be_an_instance_of(ArraySpecs::MyArray)
+    it "returns an Array instance" do
+      (@array * 0).should.instance_of?(Array)
+      (@array * 1).should.instance_of?(Array)
+      (@array * 2).should.instance_of?(Array)
     end
 
     it "does not call #initialize on the subclass instance" do
       (@array * 2).should == [1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
   end
-
-  it "copies the taint status of the original array even if the passed count is 0" do
-    ary = [1, 2, 3]
-    ary.taint
-    (ary * 0).tainted?.should == true
-  end
-
-  it "copies the taint status of the original array even if the array is empty" do
-    ary = []
-    ary.taint
-    (ary * 3).tainted?.should == true
-  end
-
-  it "copies the taint status of the original array if the passed count is not 0" do
-    ary = [1, 2, 3]
-    ary.taint
-    (ary * 1).tainted?.should == true
-    (ary * 2).tainted?.should == true
-  end
-
-  it "copies the untrusted status of the original array even if the passed count is 0" do
-    ary = [1, 2, 3]
-    ary.untrust
-    (ary * 0).untrusted?.should == true
-  end
-
-  it "copies the untrusted status of the original array even if the array is empty" do
-    ary = []
-    ary.untrust
-    (ary * 3).untrusted?.should == true
-  end
-
-  it "copies the untrusted status of the original array if the passed count is not 0" do
-    ary = [1, 2, 3]
-    ary.untrust
-    (ary * 1).untrusted?.should == true
-    (ary * 2).untrusted?.should == true
-  end
 end
 
 describe "Array#* with a string" do
diff --git a/spec/ruby/core/array/new_spec.rb b/spec/ruby/core/array/new_spec.rb
index 96ec6b8198..b2f23e2f6b 100644
--- a/spec/ruby/core/array/new_spec.rb
+++ b/spec/ruby/core/array/new_spec.rb
@@ -3,30 +3,32 @@ require_relative 'fixtures/classes'
 
 describe "Array.new" do
   it "returns an instance of Array" do
-    Array.new.should be_an_instance_of(Array)
+    Array.new.should.instance_of?(Array)
   end
 
   it "returns an instance of a subclass" do
-    ArraySpecs::MyArray.new(1, 2).should be_an_instance_of(ArraySpecs::MyArray)
+    ArraySpecs::MyArray.new(1, 2).should.instance_of?(ArraySpecs::MyArray)
   end
 
   it "raises an ArgumentError if passed 3 or more arguments" do
     -> do
       [1, 2].send :initialize, 1, 'x', true
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       [1, 2].send(:initialize, 1, 'x', true) {}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 end
 
 describe "Array.new with no arguments" do
   it "returns an empty array" do
-    Array.new.should be_empty
+    Array.new.should.empty?
   end
 
   it "does not use the given block" do
-    ->{ Array.new { raise } }.should_not raise_error
+    -> {
+      -> { Array.new { raise } }.should_not.raise
+    }.should complain(/warning: given block not used/, verbose: true)
   end
 end
 
@@ -37,7 +39,7 @@ describe "Array.new with (array)" do
   end
 
   it "does not use the given block" do
-    ->{ Array.new([1, 2]) { raise } }.should_not raise_error
+    ->{ Array.new([1, 2]) { raise } }.should_not.raise
   end
 
   it "calls #to_ary to convert the value to an array" do
@@ -54,7 +56,7 @@ describe "Array.new with (array)" do
   end
 
   it "raises a TypeError if an Array type argument and a default object" do
-    -> { Array.new([1, 2], 1) }.should raise_error(TypeError)
+    -> { Array.new([1, 2], 1) }.should.raise(TypeError)
   end
 end
 
@@ -63,8 +65,8 @@ describe "Array.new with (size, object=nil)" do
     obj = [3]
     a = Array.new(2, obj)
     a.should == [obj, obj]
-    a[0].should equal(obj)
-    a[1].should equal(obj)
+    a[0].should.equal?(obj)
+    a[1].should.equal?(obj)
 
     Array.new(3, 14).should == [14, 14, 14]
   end
@@ -74,12 +76,12 @@ describe "Array.new with (size, object=nil)" do
   end
 
   it "raises an ArgumentError if size is negative" do
-    -> { Array.new(-1, :a) }.should raise_error(ArgumentError)
-    -> { Array.new(-1) }.should raise_error(ArgumentError)
+    -> { Array.new(-1, :a) }.should.raise(ArgumentError)
+    -> { Array.new(-1) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if size is too large" do
-    -> { Array.new(fixnum_max+1) }.should raise_error(ArgumentError)
+    -> { Array.new(fixnum_max+1) }.should.raise(ArgumentError)
   end
 
   it "calls #to_int to convert the size argument to an Integer when object is given" do
@@ -97,7 +99,7 @@ describe "Array.new with (size, object=nil)" do
   it "raises a TypeError if the size argument is not an Integer type" do
     obj = mock('nonnumeric')
     obj.stub!(:to_ary).and_return([1, 2])
-    ->{ Array.new(obj, :a) }.should raise_error(TypeError)
+    ->{ Array.new(obj, :a) }.should.raise(TypeError)
   end
 
   it "yields the index of the element and sets the element to the value of the block" do
diff --git a/spec/ruby/core/array/none_spec.rb b/spec/ruby/core/array/none_spec.rb
new file mode 100644
index 0000000000..31cd8c46d6
--- /dev/null
+++ b/spec/ruby/core/array/none_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
+
+describe "Array#none?" do
+  @value_to_return = -> _ { false }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :none?
+
+  it "ignores the block if there is an argument" do
+    -> {
+      ['bar', 'foobar'].none?(/baz/) { true }.should == true
+    }.should complain(/given block not used/)
+  end
+end
diff --git a/spec/ruby/core/array/one_spec.rb b/spec/ruby/core/array/one_spec.rb
new file mode 100644
index 0000000000..0c61907881
--- /dev/null
+++ b/spec/ruby/core/array/one_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
+
+describe "Array#one?" do
+  @value_to_return = -> _ { false }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :one?
+
+  it "ignores the block if there is an argument" do
+    -> {
+      ['bar', 'foobar'].one?(/foo/) { false }.should == true
+    }.should complain(/given block not used/)
+  end
+end
diff --git a/spec/ruby/core/array/pack/a_spec.rb b/spec/ruby/core/array/pack/a_spec.rb
index 7af7a16c68..03bfd8214c 100644
--- a/spec/ruby/core/array/pack/a_spec.rb
+++ b/spec/ruby/core/array/pack/a_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -12,11 +12,22 @@ describe "Array#pack with format 'A'" do
   it_behaves_like :array_pack_string, 'A'
   it_behaves_like :array_pack_taint, 'A'
 
+  it "calls #to_str to convert an Object to a String" do
+    obj = mock("pack A string")
+    obj.should_receive(:to_str).and_return("``abcdef")
+    [obj].pack("A*").should == "``abcdef"
+  end
+
+  it "will not implicitly convert a number to a string" do
+    -> { [0].pack('A') }.should.raise(TypeError)
+    -> { [0].pack('a') }.should.raise(TypeError)
+  end
+
   it "adds all the bytes to the output when passed the '*' modifier" do
     ["abc"].pack("A*").should == "abc"
   end
 
-  it "padds the output with spaces when the count exceeds the size of the String" do
+  it "pads the output with spaces when the count exceeds the size of the String" do
     ["abc"].pack("A6").should == "abc   "
   end
 
@@ -44,7 +55,7 @@ describe "Array#pack with format 'a'" do
     ["abc"].pack("a*").should == "abc"
   end
 
-  it "padds the output with NULL bytes when the count exceeds the size of the String" do
+  it "pads the output with NULL bytes when the count exceeds the size of the String" do
     ["abc"].pack("a6").should == "abc\x00\x00\x00"
   end
 
diff --git a/spec/ruby/core/array/pack/at_spec.rb b/spec/ruby/core/array/pack/at_spec.rb
index 3942677913..bb9801440a 100644
--- a/spec/ruby/core/array/pack/at_spec.rb
+++ b/spec/ruby/core/array/pack/at_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
diff --git a/spec/ruby/core/array/pack/b_spec.rb b/spec/ruby/core/array/pack/b_spec.rb
index 872c1b88d5..f7576846ef 100644
--- a/spec/ruby/core/array/pack/b_spec.rb
+++ b/spec/ruby/core/array/pack/b_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -13,11 +13,16 @@ describe "Array#pack with format 'B'" do
   it_behaves_like :array_pack_taint, 'B'
 
   it "calls #to_str to convert an Object to a String" do
-    obj = mock("pack H string")
+    obj = mock("pack B string")
     obj.should_receive(:to_str).and_return("``abcdef")
     [obj].pack("B*").should == "\x2a"
   end
 
+  it "will not implicitly convert a number to a string" do
+    -> { [0].pack('B') }.should.raise(TypeError)
+    -> { [0].pack('b') }.should.raise(TypeError)
+  end
+
   it "encodes one bit for each character starting with the most significant bit" do
     [ [["0"], "\x00"],
       [["1"], "\x80"]
diff --git a/spec/ruby/core/array/pack/buffer_spec.rb b/spec/ruby/core/array/pack/buffer_spec.rb
index ecb40bfd06..d104c80186 100644
--- a/spec/ruby/core/array/pack/buffer_spec.rb
+++ b/spec/ruby/core/array/pack/buffer_spec.rb
@@ -7,43 +7,53 @@ describe "Array#pack with :buffer option" do
     n = [ 65, 66, 67 ]
     buffer = " "*3
     result = n.pack("ccc", buffer: buffer)      #=> "ABC"
-    result.should equal(buffer)
+    result.should.equal?(buffer)
   end
 
   it "adds result at the end of buffer content" do
     n = [ 65, 66, 67 ] # result without buffer is "ABC"
 
-    buffer = ""
+    buffer = +""
     n.pack("ccc", buffer: buffer).should == "ABC"
 
-    buffer = "123"
+    buffer = +"123"
     n.pack("ccc", buffer: buffer).should == "123ABC"
 
-    buffer = "12345"
+    buffer = +"12345"
     n.pack("ccc", buffer: buffer).should == "12345ABC"
   end
 
   it "raises TypeError exception if buffer is not String" do
-    -> { [65].pack("ccc", buffer: []) }.should raise_error(
+    -> { [65].pack("ccc", buffer: []) }.should.raise(
       TypeError, "buffer must be String, not Array")
   end
 
+  it "raise FrozenError if buffer is frozen" do
+    -> { [65].pack("c", buffer: "frozen-string".freeze) }.should.raise(FrozenError)
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    [65, 66, 67].pack("ccc", buffer: buffer)
+    buffer.encoding.should == Encoding::ISO_8859_1
+  end
+
   context "offset (@) is specified" do
     it 'keeps buffer content if it is longer than offset' do
       n = [ 65, 66, 67 ]
-      buffer = "123456"
+      buffer = +"123456"
       n.pack("@3ccc", buffer: buffer).should == "123ABC"
     end
 
     it "fills the gap with \\0 if buffer content is shorter than offset" do
       n = [ 65, 66, 67 ]
-      buffer = "123"
+      buffer = +"123"
       n.pack("@6ccc", buffer: buffer).should == "123\0\0\0ABC"
     end
 
     it 'does not keep buffer content if it is longer than offset + result' do
       n = [ 65, 66, 67 ]
-      buffer = "1234567890"
+      buffer = +"1234567890"
       n.pack("@3ccc", buffer: buffer).should == "123ABC"
     end
   end
diff --git a/spec/ruby/core/array/pack/c_spec.rb b/spec/ruby/core/array/pack/c_spec.rb
index 7200830331..de06207a23 100644
--- a/spec/ruby/core/array/pack/c_spec.rb
+++ b/spec/ruby/core/array/pack/c_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
@@ -45,8 +45,10 @@ describe :array_pack_8bit, shared: true do
     [1, 2, 3, 4, 5].pack(pack_format('*')).should == "\x01\x02\x03\x04\x05"
   end
 
-  it "ignores NULL bytes between directives" do
-    [1, 2, 3].pack(pack_format("\000", 2)).should == "\x01\x02"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [1, 2, 3].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/array/pack/comment_spec.rb b/spec/ruby/core/array/pack/comment_spec.rb
index 254c827ccc..daf1cff06a 100644
--- a/spec/ruby/core/array/pack/comment_spec.rb
+++ b/spec/ruby/core/array/pack/comment_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
diff --git a/spec/ruby/core/array/pack/h_spec.rb b/spec/ruby/core/array/pack/h_spec.rb
index 85a875fc8b..1492d02b1f 100644
--- a/spec/ruby/core/array/pack/h_spec.rb
+++ b/spec/ruby/core/array/pack/h_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -18,6 +18,11 @@ describe "Array#pack with format 'H'" do
     [obj].pack("H").should == "\xa0"
   end
 
+  it "will not implicitly convert a number to a string" do
+    -> { [0].pack('H') }.should.raise(TypeError)
+    -> { [0].pack('h') }.should.raise(TypeError)
+  end
+
   it "encodes the first character as the most significant nibble when passed no count modifier" do
     ["ab"].pack("H").should == "\xa0"
   end
diff --git a/spec/ruby/core/array/pack/l_spec.rb b/spec/ruby/core/array/pack/l_spec.rb
index b446a7a36a..f6dfb1da83 100644
--- a/spec/ruby/core/array/pack/l_spec.rb
+++ b/spec/ruby/core/array/pack/l_spec.rb
@@ -29,7 +29,7 @@ describe "Array#pack with format 'L'" do
     it_behaves_like :array_pack_32bit_be, 'L>'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :array_pack_32bit_le, 'L<_'
       it_behaves_like :array_pack_32bit_le, 'L_<'
@@ -51,7 +51,7 @@ describe "Array#pack with format 'L'" do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :array_pack_64bit_le, 'L<_'
       it_behaves_like :array_pack_64bit_le, 'L_<'
@@ -83,7 +83,7 @@ describe "Array#pack with format 'l'" do
     it_behaves_like :array_pack_32bit_be, 'l>'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :array_pack_32bit_le, 'l<_'
       it_behaves_like :array_pack_32bit_le, 'l_<'
@@ -105,7 +105,7 @@ describe "Array#pack with format 'l'" do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :array_pack_64bit_le, 'l<_'
       it_behaves_like :array_pack_64bit_le, 'l_<'
@@ -137,7 +137,7 @@ little_endian do
     it_behaves_like :array_pack_32bit_le, 'l'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "Array#pack with format 'L' with modifier '_'" do
       it_behaves_like :array_pack_32bit_le, 'L_'
     end
@@ -155,7 +155,7 @@ little_endian do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "Array#pack with format 'L' with modifier '_'" do
       it_behaves_like :array_pack_64bit_le, 'L_'
     end
@@ -183,7 +183,7 @@ big_endian do
     it_behaves_like :array_pack_32bit_be, 'l'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "Array#pack with format 'L' with modifier '_'" do
       it_behaves_like :array_pack_32bit_be, 'L_'
     end
@@ -201,7 +201,7 @@ big_endian do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "Array#pack with format 'L' with modifier '_'" do
       it_behaves_like :array_pack_64bit_be, 'L_'
     end
diff --git a/spec/ruby/core/array/pack/m_spec.rb b/spec/ruby/core/array/pack/m_spec.rb
index 2b1a84abca..fb670d120e 100644
--- a/spec/ruby/core/array/pack/m_spec.rb
+++ b/spec/ruby/core/array/pack/m_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -80,8 +80,16 @@ describe "Array#pack with format 'M'" do
     ].should be_computed_by(:pack, "M")
   end
 
-  it "encodes a tab followed by a newline with an encoded newline" do
+  it "encodes a tab at the end of a line with an encoded newline" do
+    ["\t"].pack("M").should == "\t=\n"
     ["\t\n"].pack("M").should == "\t=\n\n"
+    ["abc\t\nxyz"].pack("M").should == "abc\t=\n\nxyz=\n"
+  end
+
+  it "encodes a space at the end of a line with an encoded newline" do
+    [" "].pack("M").should == " =\n"
+    [" \n"].pack("M").should == " =\n\n"
+    ["abc \nxyz"].pack("M").should == "abc =\n\nxyz=\n"
   end
 
   it "encodes 127..255 in hex format" do
@@ -147,7 +155,7 @@ describe "Array#pack with format 'M'" do
 
   it "encodes a recursive array" do
     empty = ArraySpecs.empty_recursive_array
-    empty.pack('M').should be_an_instance_of(String)
+    empty.pack('M').should.instance_of?(String)
 
     array = ArraySpecs.recursive_array
     array.pack('M').should == "1=\n"
@@ -164,7 +172,7 @@ describe "Array#pack with format 'M'" do
     obj = mock("pack M non-string")
     obj.should_receive(:to_s).and_return(2)
 
-    [obj].pack("M").should be_an_instance_of(String)
+    [obj].pack("M").should.instance_of?(String)
   end
 
   it "encodes a Symbol as a String" do
@@ -285,16 +293,16 @@ describe "Array#pack with format 'm'" do
 
   it "raises a TypeError if #to_str does not return a String" do
     obj = mock("pack m non-string")
-    -> { [obj].pack("m") }.should raise_error(TypeError)
+    -> { [obj].pack("m") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
-    -> { [nil].pack("m") }.should raise_error(TypeError)
+    -> { [nil].pack("m") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an Integer" do
-    -> { [0].pack("m") }.should raise_error(TypeError)
-    -> { [bignum_value].pack("m") }.should raise_error(TypeError)
+    -> { [0].pack("m") }.should.raise(TypeError)
+    -> { [bignum_value].pack("m") }.should.raise(TypeError)
   end
 
   it "does not emit a newline if passed zero as the count modifier" do
diff --git a/spec/ruby/core/array/pack/p_spec.rb b/spec/ruby/core/array/pack/p_spec.rb
index 857d403313..b023bf9110 100644
--- a/spec/ruby/core/array/pack/p_spec.rb
+++ b/spec/ruby/core/array/pack/p_spec.rb
@@ -15,16 +15,6 @@ describe "Array#pack with format 'P'" do
     ["hello"].pack("P").unpack("P5").should == ["hello"]
   end
 
-  it "taints the input string" do
-    input_string = "hello"
-    [input_string].pack("P")
-    input_string.tainted?.should be_true
-  end
-
-  it "does not taint the output string in normal cases" do
-    ["hello"].pack("P").tainted?.should be_false
-  end
-
   it "with nil gives a null pointer" do
     [nil].pack("P").unpack("J").should == [0]
   end
@@ -42,16 +32,6 @@ describe "Array#pack with format 'p'" do
     ["hello"].pack("p").unpack("p").should == ["hello"]
   end
 
-  it "taints the input string" do
-    input_string = "hello"
-    [input_string].pack("p")
-    input_string.tainted?.should be_true
-  end
-
-  it "does not taint the output string in normal cases" do
-    ["hello"].pack("p").tainted?.should be_false
-  end
-
   it "with nil gives a null pointer" do
     [nil].pack("p").unpack("J").should == [0]
   end
diff --git a/spec/ruby/core/array/pack/percent_spec.rb b/spec/ruby/core/array/pack/percent_spec.rb
index 5d56dea5fe..29b119732a 100644
--- a/spec/ruby/core/array/pack/percent_spec.rb
+++ b/spec/ruby/core/array/pack/percent_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../../spec_helper'
 
 describe "Array#pack with format '%'" do
   it "raises an Argument Error" do
-    -> { [1].pack("%") }.should raise_error(ArgumentError)
+    -> { [1].pack("%") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/array/pack/r_spec.rb b/spec/ruby/core/array/pack/r_spec.rb
new file mode 100644
index 0000000000..cefe1388d2
--- /dev/null
+++ b/spec/ruby/core/array/pack/r_spec.rb
@@ -0,0 +1,89 @@
+# encoding: binary
+require_relative '../../../spec_helper'
+require_relative '../fixtures/classes'
+require_relative 'shared/basic'
+require_relative 'shared/numeric_basic'
+require_relative 'shared/integer'
+
+ruby_version_is "4.1" do
+  describe "Array#pack with format 'R'" do
+    it_behaves_like :array_pack_basic, 'R'
+    it_behaves_like :array_pack_basic_non_float, 'R'
+    it_behaves_like :array_pack_arguments, 'R'
+    it_behaves_like :array_pack_numeric_basic, 'R'
+    it_behaves_like :array_pack_integer, 'R'
+
+    it "encodes a ULEB128 integer" do
+      [ [[0],            "\x00"],
+        [[1],            "\x01"],
+        [[127],          "\x7f"],
+        [[128],          "\x80\x01"],
+        [[0x3fff],       "\xff\x7f"],
+        [[0x4000],       "\x80\x80\x01"],
+        [[0xffffffff],   "\xff\xff\xff\xff\x0f"],
+        [[0x100000000],  "\x80\x80\x80\x80\x10"],
+        [[0xffff_ffff_ffff_ffff], "\xff\xff\xff\xff\xff\xff\xff\xff\xff\x01"],
+        [[0xffff_ffff_ffff_ffff_ffff_ffff], "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x1f"],
+      ].should be_computed_by(:pack, "R")
+    end
+
+    it "encodes multiple values with '*' modifier" do
+      [1, 2].pack("R*").should == "\x01\x02"
+      [127, 128].pack("R*").should == "\x7f\x80\x01"
+    end
+
+    it "raises an ArgumentError when passed a negative value" do
+      -> { [-1].pack("R") }.should.raise(ArgumentError)
+      -> { [-100].pack("R") }.should.raise(ArgumentError)
+    end
+
+    it "round-trips values through pack and unpack" do
+      values = [0, 1, 127, 128, 0x3fff, 0x4000, 0xffffffff, 0x100000000]
+      values.pack("R*").unpack("R*").should == values
+    end
+  end
+
+  describe "Array#pack with format 'r'" do
+    it_behaves_like :array_pack_basic, 'r'
+    it_behaves_like :array_pack_basic_non_float, 'r'
+    it_behaves_like :array_pack_arguments, 'r'
+    it_behaves_like :array_pack_numeric_basic, 'r'
+    it_behaves_like :array_pack_integer, 'r'
+
+    it "encodes a SLEB128 integer" do
+      [ [[0],     "\x00"],
+        [[1],     "\x01"],
+        [[-1],    "\x7f"],
+        [[-2],    "\x7e"],
+        [[127],   "\xff\x00"],
+        [[128],   "\x80\x01"],
+        [[-127],  "\x81\x7f"],
+        [[-128],  "\x80\x7f"],
+      ].should be_computed_by(:pack, "r")
+    end
+
+    it "encodes larger positive numbers" do
+      [0x3fff].pack("r").should == "\xff\xff\x00"
+      [0x4000].pack("r").should == "\x80\x80\x01"
+    end
+
+    it "encodes larger negative numbers" do
+      [-0x3fff].pack("r").should == "\x81\x80\x7f"
+      [-0x4000].pack("r").should == "\x80\x80\x7f"
+    end
+
+    it "encodes very large numbers" do
+      [0xffff_ffff_ffff_ffff_ffff_ffff].pack("r").should == "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\x1F"
+      [-0xffff_ffff_ffff_ffff_ffff_ffff].pack("r").should == "\x81\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x60"
+    end
+
+    it "encodes multiple values with '*' modifier" do
+      [0, 1, -1].pack("r*").should == "\x00\x01\x7f"
+    end
+
+    it "round-trips values through pack and unpack" do
+      values = [0, 1, -1, 127, -127, 128, -128, 0x3fff, -0x3fff, 0x4000, -0x4000]
+      values.pack("r*").unpack("r*").should == values
+    end
+  end
+end
diff --git a/spec/ruby/core/array/pack/shared/basic.rb b/spec/ruby/core/array/pack/shared/basic.rb
index bc366987c8..2894369c71 100644
--- a/spec/ruby/core/array/pack/shared/basic.rb
+++ b/spec/ruby/core/array/pack/shared/basic.rb
@@ -1,6 +1,6 @@
 describe :array_pack_arguments, shared: true do
   it "raises an ArgumentError if there are fewer elements than the format requires" do
-    -> { [].pack(pack_format(1)) }.should raise_error(ArgumentError)
+    -> { [].pack(pack_format(1)) }.should.raise(ArgumentError)
   end
 end
 
@@ -10,11 +10,11 @@ describe :array_pack_basic, shared: true do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { [@obj].pack(nil) }.should raise_error(TypeError)
+    -> { [@obj].pack(nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed an Integer" do
-    -> { [@obj].pack(1) }.should raise_error(TypeError)
+    -> { [@obj].pack(1) }.should.raise(TypeError)
   end
 end
 
@@ -24,42 +24,50 @@ describe :array_pack_basic_non_float, shared: true do
   end
 
   it "ignores whitespace in the format string" do
-    [@obj, @obj].pack("a \t\n\v\f\r"+pack_format).should be_an_instance_of(String)
+    [@obj, @obj].pack("a \t\n\v\f\r"+pack_format).should.instance_of?(String)
+  end
+
+  it "ignores comments in the format string" do
+    # 2 additional directives ('a') are required for the X directive
+    [@obj, @obj, @obj, @obj].pack("aa #{pack_format} # some comment \n#{pack_format}").should.instance_of?(String)
+  end
+
+  it "raise ArgumentError when a directive is unknown" do
+    # additional directive ('a') is required for the X directive
+    -> { [@obj, @obj].pack("a K" + pack_format) }.should.raise(ArgumentError, /unknown pack directive 'K'/)
+    -> { [@obj, @obj].pack("a 0" + pack_format) }.should.raise(ArgumentError, /unknown pack directive '0'/)
+    -> { [@obj, @obj].pack("a :" + pack_format) }.should.raise(ArgumentError, /unknown pack directive ':'/)
   end
 
   it "calls #to_str to coerce the directives string" do
     d = mock("pack directive")
     d.should_receive(:to_str).and_return("x"+pack_format)
-    [@obj, @obj].pack(d).should be_an_instance_of(String)
-  end
-
-  it "taints the output string if the format string is tainted" do
-    [@obj, @obj].pack("x"+pack_format.taint).tainted?.should be_true
+    [@obj, @obj].pack(d).should.instance_of?(String)
   end
 end
 
 describe :array_pack_basic_float, shared: true do
   it "ignores whitespace in the format string" do
-    [9.3, 4.7].pack(" \t\n\v\f\r"+pack_format).should be_an_instance_of(String)
+    [9.3, 4.7].pack(" \t\n\v\f\r"+pack_format).should.instance_of?(String)
+  end
+
+  it "ignores comments in the format string" do
+    [9.3, 4.7].pack(pack_format + "# some comment \n" + pack_format).should.instance_of?(String)
   end
 
   it "calls #to_str to coerce the directives string" do
     d = mock("pack directive")
     d.should_receive(:to_str).and_return("x"+pack_format)
-    [1.2, 4.7].pack(d).should be_an_instance_of(String)
-  end
-
-  it "taints the output string if the format string is tainted" do
-    [3.2, 2.8].pack("x"+pack_format.taint).tainted?.should be_true
+    [1.2, 4.7].pack(d).should.instance_of?(String)
   end
 end
 
 describe :array_pack_no_platform, shared: true do
   it "raises ArgumentError when the format modifier is '_'" do
-    ->{ [1].pack(pack_format("_")) }.should raise_error(ArgumentError)
+    ->{ [1].pack(pack_format("_")) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError when the format modifier is '!'" do
-    ->{ [1].pack(pack_format("!")) }.should raise_error(ArgumentError)
+    ->{ [1].pack(pack_format("!")) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/array/pack/shared/encodings.rb b/spec/ruby/core/array/pack/shared/encodings.rb
index 6b7ffac764..0b5a5cc8a0 100644
--- a/spec/ruby/core/array/pack/shared/encodings.rb
+++ b/spec/ruby/core/array/pack/shared/encodings.rb
@@ -5,12 +5,12 @@ describe :array_pack_hex, shared: true do
 
   it "raises a TypeError if the object does not respond to #to_str" do
     obj = mock("pack hex non-string")
-    -> { [obj].pack(pack_format) }.should raise_error(TypeError)
+    -> { [obj].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_str does not return a String" do
     obj = mock("pack hex non-string")
     obj.should_receive(:to_str).and_return(1)
-    -> { [obj].pack(pack_format) }.should raise_error(TypeError)
+    -> { [obj].pack(pack_format) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/array/pack/shared/float.rb b/spec/ruby/core/array/pack/shared/float.rb
index c6b194007f..c1efcd7677 100644
--- a/spec/ruby/core/array/pack/shared/float.rb
+++ b/spec/ruby/core/array/pack/shared/float.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :array_pack_float_le, shared: true do
   it "encodes a positive Float" do
@@ -14,7 +14,7 @@ describe :array_pack_float_le, shared: true do
   end
 
   it "raises a TypeError if passed a String representation of a floating point number" do
-    -> { ["13"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["13"].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "encodes the number of array elements specified by the count modifier" do
@@ -25,8 +25,10 @@ describe :array_pack_float_le, shared: true do
     [2.9, 1.4, 8.2].pack(pack_format("*")).should == "\x9a\x999@33\xb3?33\x03A"
   end
 
-  it "ignores NULL bytes between directives" do
-    [5.3, 9.2].pack(pack_format("\000", 2)).should == "\x9a\x99\xa9@33\x13A"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [5.3, 9.2].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -43,7 +45,7 @@ describe :array_pack_float_le, shared: true do
 
   it "encodes NaN" do
     nans = ["\x00\x00\xc0\xff", "\x00\x00\xc0\x7f", "\xFF\xFF\xFF\x7F"]
-    nans.should include([nan_value].pack(pack_format))
+    nans.should.include?([nan_value].pack(pack_format))
   end
 
   it "encodes a positive Float outside the range of a single precision float" do
@@ -53,6 +55,14 @@ describe :array_pack_float_le, shared: true do
   it "encodes a negative Float outside the range of a single precision float" do
     [-1e150].pack(pack_format).should == "\x00\x00\x80\xff"
   end
+
+  it "encodes a bignum as a float" do
+    [2 ** 65].pack(pack_format).should == [(2 ** 65).to_f].pack(pack_format)
+  end
+
+  it "encodes a rational as a float" do
+    [Rational(3, 4)].pack(pack_format).should == [Rational(3, 4).to_f].pack(pack_format)
+  end
 end
 
 describe :array_pack_float_be, shared: true do
@@ -66,10 +76,15 @@ describe :array_pack_float_be, shared: true do
 
   it "converts an Integer to a Float" do
     [8].pack(pack_format).should == "A\x00\x00\x00"
+    [bignum_value].pack(pack_format).should == "_\x80\x00\x00"
+  end
+
+  it "converts a Rational to a Float" do
+    [Rational(8)].pack(pack_format).should == "A\x00\x00\x00"
   end
 
   it "raises a TypeError if passed a String representation of a floating point number" do
-    -> { ["13"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["13"].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "encodes the number of array elements specified by the count modifier" do
@@ -80,8 +95,10 @@ describe :array_pack_float_be, shared: true do
     [2.9, 1.4, 8.2].pack(pack_format("*")).should == "@9\x99\x9a?\xb333A\x0333"
   end
 
-  it "ignores NULL bytes between directives" do
-    [5.3, 9.2].pack(pack_format("\000", 2)).should == "@\xa9\x99\x9aA\x1333"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [5.3, 9.2].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -98,7 +115,7 @@ describe :array_pack_float_be, shared: true do
 
   it "encodes NaN" do
     nans = ["\xff\xc0\x00\x00", "\x7f\xc0\x00\x00", "\x7F\xFF\xFF\xFF"]
-    nans.should include([nan_value].pack(pack_format))
+    nans.should.include?([nan_value].pack(pack_format))
   end
 
   it "encodes a positive Float outside the range of a single precision float" do
@@ -121,10 +138,15 @@ describe :array_pack_double_le, shared: true do
 
   it "converts an Integer to a Float" do
     [8].pack(pack_format).should == "\x00\x00\x00\x00\x00\x00\x20@"
+    [bignum_value].pack(pack_format).should == "\x00\x00\x00\x00\x00\x00\xF0C"
+  end
+
+  it "converts a Rational to a Float" do
+    [Rational(8)].pack(pack_format).should == "\x00\x00\x00\x00\x00\x00 @"
   end
 
   it "raises a TypeError if passed a String representation of a floating point number" do
-    -> { ["13"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["13"].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "encodes the number of array elements specified by the count modifier" do
@@ -135,8 +157,10 @@ describe :array_pack_double_le, shared: true do
     [2.9, 1.4, 8.2].pack(pack_format("*")).should == "333333\x07@ffffff\xf6?ffffff\x20@"
   end
 
-  it "ignores NULL bytes between directives" do
-    [5.3, 9.2].pack(pack_format("\000", 2)).should == "333333\x15@ffffff\x22@"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [5.3, 9.2].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -157,7 +181,7 @@ describe :array_pack_double_le, shared: true do
       "\x00\x00\x00\x00\x00\x00\xf8\x7f",
       "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\x7F"
     ]
-    nans.should include([nan_value].pack(pack_format))
+    nans.should.include?([nan_value].pack(pack_format))
   end
 
   it "encodes a positive Float outside the range of a single precision float" do
@@ -183,7 +207,7 @@ describe :array_pack_double_be, shared: true do
   end
 
   it "raises a TypeError if passed a String representation of a floating point number" do
-    -> { ["13"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["13"].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "encodes the number of array elements specified by the count modifier" do
@@ -194,8 +218,10 @@ describe :array_pack_double_be, shared: true do
     [2.9, 1.4, 8.2].pack(pack_format("*")).should == "@\x07333333?\xf6ffffff@\x20ffffff"
   end
 
-  it "ignores NULL bytes between directives" do
-    [5.3, 9.2].pack(pack_format("\000", 2)).should == "@\x15333333@\x22ffffff"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [5.3, 9.2].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -216,7 +242,7 @@ describe :array_pack_double_be, shared: true do
       "\x7f\xf8\x00\x00\x00\x00\x00\x00",
       "\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF"
     ]
-    nans.should include([nan_value].pack(pack_format))
+    nans.should.include?([nan_value].pack(pack_format))
   end
 
   it "encodes a positive Float outside the range of a single precision float" do
diff --git a/spec/ruby/core/array/pack/shared/integer.rb b/spec/ruby/core/array/pack/shared/integer.rb
index 6592f85022..1cdd386cc1 100644
--- a/spec/ruby/core/array/pack/shared/integer.rb
+++ b/spec/ruby/core/array/pack/shared/integer.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :array_pack_16bit_le, shared: true do
   it "encodes the least significant 16 bits of a positive number" do
@@ -41,9 +41,10 @@ describe :array_pack_16bit_le, shared: true do
     str.should == "\x78\x65\xcd\xab\x21\x43"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
-    str.should == "\x78\x65\xcd\xab"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -93,9 +94,10 @@ describe :array_pack_16bit_be, shared: true do
     str.should == "\x65\x78\xab\xcd\x43\x21"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
-    str.should == "\x65\x78\xab\xcd"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -145,9 +147,10 @@ describe :array_pack_32bit_le, shared: true do
     str.should == "\x78\x65\x43\x12\xcd\xab\xf0\xde\x21\x43\x65\x78"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
-    str.should == "\x78\x65\x43\x12\xcd\xab\xf0\xde"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -197,9 +200,10 @@ describe :array_pack_32bit_be, shared: true do
     str.should == "\x12\x43\x65\x78\xde\xf0\xab\xcd\x78\x65\x43\x21"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
-    str.should == "\x12\x43\x65\x78\xde\xf0\xab\xcd"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0x1243_6578, 0xdef0_abcd].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -225,7 +229,7 @@ describe :array_pack_32bit_le_platform, shared: true do
     str.should == "\x78\x65\x43\x12\xcd\xab\xf0\xde\x21\x43\x65\x78"
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     it "encodes the least significant 32 bits of a number that is greater than 32 bits" do
       [ [[0xff_7865_4321],  "\x21\x43\x65\x78"],
         [[-0xff_7865_4321], "\xdf\xbc\x9a\x87"]
@@ -251,7 +255,7 @@ describe :array_pack_32bit_be_platform, shared: true do
     str.should == "\x12\x43\x65\x78\xde\xf0\xab\xcd\x78\x65\x43\x21"
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     it "encodes the least significant 32 bits of a number that is greater than 32 bits" do
       [ [[0xff_7865_4321],  "\x78\x65\x43\x21"],
         [[-0xff_7865_4321], "\x87\x9a\xbc\xdf"]
@@ -309,9 +313,10 @@ describe :array_pack_64bit_le, shared: true do
     str.should == "\x56\x78\x12\x34\xcd\xab\xf0\xde\xf0\xde\xba\xdc\x21\x43\x65\x78"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0xdef0_abcd_3412_7856, 0x7865_4321_dcba_def0].pack(pack_format("\000", 2))
-    str.should == "\x56\x78\x12\x34\xcd\xab\xf0\xde\xf0\xde\xba\xdc\x21\x43\x65\x78"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0xdef0_abcd_3412_7856, 0x7865_4321_dcba_def0].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -369,9 +374,10 @@ describe :array_pack_64bit_be, shared: true do
     str.should == "\xde\xf0\xab\xcd\x34\x12\x78\x56\x78\x65\x43\x21\xdc\xba\xde\xf0"
   end
 
-  it "ignores NULL bytes between directives" do
-    str = [0xdef0_abcd_3412_7856, 0x7865_4321_dcba_def0].pack(pack_format("\000", 2))
-    str.should == "\xde\xf0\xab\xcd\x34\x12\x78\x56\x78\x65\x43\x21\xdc\xba\xde\xf0"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [0xdef0_abcd_3412_7856, 0x7865_4321_dcba_def0].pack(pack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/array/pack/shared/numeric_basic.rb b/spec/ruby/core/array/pack/shared/numeric_basic.rb
index 7c36ba4a32..6594914933 100644
--- a/spec/ruby/core/array/pack/shared/numeric_basic.rb
+++ b/spec/ruby/core/array/pack/shared/numeric_basic.rb
@@ -4,15 +4,15 @@ describe :array_pack_numeric_basic, shared: true do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { [nil].pack(pack_format) }.should raise_error(TypeError)
+    -> { [nil].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed true" do
-    -> { [true].pack(pack_format) }.should raise_error(TypeError)
+    -> { [true].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed false" do
-    -> { [false].pack(pack_format) }.should raise_error(TypeError)
+    -> { [false].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "returns a binary string" do
@@ -24,21 +24,27 @@ end
 describe :array_pack_integer, shared: true do
   it "raises a TypeError when the object does not respond to #to_int" do
     obj = mock('not an integer')
-    -> { [obj].pack(pack_format) }.should raise_error(TypeError)
+    -> { [obj].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { ["5"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["5"].pack(pack_format) }.should.raise(TypeError)
   end
 end
 
 describe :array_pack_float, shared: true do
   it "raises a TypeError if a String does not represent a floating point number" do
-    -> { ["a"].pack(pack_format) }.should raise_error(TypeError)
+    -> { ["a"].pack(pack_format) }.should.raise(TypeError)
   end
 
-  it "raises a TypeError when the object does not respond to #to_f" do
-    obj = mock('not an float')
-    -> { [obj].pack(pack_format) }.should raise_error(TypeError)
+  it "raises a TypeError when the object is not Numeric" do
+    obj = Object.new
+    -> { [obj].pack(pack_format) }.should.raise(TypeError, /can't convert Object into Float/)
+  end
+
+  it "raises a TypeError when the Numeric object does not respond to #to_f" do
+    klass = Class.new(Numeric)
+    obj = klass.new
+    -> { [obj].pack(pack_format) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/array/pack/shared/string.rb b/spec/ruby/core/array/pack/shared/string.rb
index 8c82e8c617..b02257059f 100644
--- a/spec/ruby/core/array/pack/shared/string.rb
+++ b/spec/ruby/core/array/pack/shared/string.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 describe :array_pack_string, shared: true do
   it "adds count bytes of a String to the output" do
     ["abc"].pack(pack_format(2)).should == "ab"
@@ -17,11 +17,11 @@ describe :array_pack_string, shared: true do
   end
 
   it "raises an ArgumentError when the Array is empty" do
-    -> { [].pack(pack_format) }.should raise_error(ArgumentError)
+    -> { [].pack(pack_format) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the Array has too few elements" do
-    -> { ["a"].pack(pack_format(nil, 2)) }.should raise_error(ArgumentError)
+    -> { ["a"].pack(pack_format(nil, 2)) }.should.raise(ArgumentError)
   end
 
   it "calls #to_str to convert the element to a String" do
@@ -33,14 +33,14 @@ describe :array_pack_string, shared: true do
 
   it "raises a TypeError when the object does not respond to #to_str" do
     obj = mock("not a string")
-    -> { [obj].pack(pack_format) }.should raise_error(TypeError)
+    -> { [obj].pack(pack_format) }.should.raise(TypeError)
   end
 
   it "returns a string in encoding of common to the concatenated results" do
     f = pack_format("*")
     [ [["\u{3042 3044 3046 3048}", 0x2000B].pack(f+"U"),       Encoding::BINARY],
       [["abcde\xd1", "\xFF\xFe\x81\x82"].pack(f+"u"),          Encoding::BINARY],
-      [["a".force_encoding("ascii"), "\xFF\xFe\x81\x82"].pack(f+"u"), Encoding::BINARY],
+      [["a".dup.force_encoding("ascii"), "\xFF\xFe\x81\x82"].pack(f+"u"), Encoding::BINARY],
       # under discussion [ruby-dev:37294]
       [["\u{3042 3044 3046 3048}", 1].pack(f+"N"),             Encoding::BINARY]
     ].should be_computed_by(:encoding)
diff --git a/spec/ruby/core/array/pack/shared/taint.rb b/spec/ruby/core/array/pack/shared/taint.rb
index 88f349cb24..2c2b011c34 100644
--- a/spec/ruby/core/array/pack/shared/taint.rb
+++ b/spec/ruby/core/array/pack/shared/taint.rb
@@ -1,33 +1,2 @@
 describe :array_pack_taint, shared: true do
-  it "returns a tainted string when a pack argument is tainted" do
-    ["abcd".taint, 0x20].pack(pack_format("3C")).tainted?.should be_true
-  end
-
-  it "does not return a tainted string when the array is tainted" do
-    ["abcd", 0x20].taint.pack(pack_format("3C")).tainted?.should be_false
-  end
-
-  it "returns a tainted string when the format is tainted" do
-    ["abcd", 0x20].pack(pack_format("3C").taint).tainted?.should be_true
-  end
-
-  it "returns a tainted string when an empty format is tainted" do
-    ["abcd", 0x20].pack("".taint).tainted?.should be_true
-  end
-
-  it "returns a untrusted string when the format is untrusted" do
-    ["abcd", 0x20].pack(pack_format("3C").untrust).untrusted?.should be_true
-  end
-
-  it "returns a untrusted string when the empty format is untrusted" do
-    ["abcd", 0x20].pack("".untrust).untrusted?.should be_true
-  end
-
-  it "returns a untrusted string when a pack argument is untrusted" do
-    ["abcd".untrust, 0x20].pack(pack_format("3C")).untrusted?.should be_true
-  end
-
-  it "returns a trusted string when the array is untrusted" do
-    ["abcd", 0x20].untrust.pack(pack_format("3C")).untrusted?.should be_false
-  end
 end
diff --git a/spec/ruby/core/array/pack/shared/unicode.rb b/spec/ruby/core/array/pack/shared/unicode.rb
index dd0f8b38aa..58ba8a8b23 100644
--- a/spec/ruby/core/array/pack/shared/unicode.rb
+++ b/spec/ruby/core/array/pack/shared/unicode.rb
@@ -26,7 +26,7 @@ describe :array_pack_unicode, shared: true do
   it "constructs strings with valid encodings" do
     str = [0x85].pack("U*")
     str.should == "\xc2\x85"
-    str.valid_encoding?.should be_true
+    str.valid_encoding?.should == true
   end
 
   it "encodes values larger than UTF-8 max codepoints" do
@@ -64,11 +64,13 @@ describe :array_pack_unicode, shared: true do
   it "raises a TypeError if #to_int does not return an Integer" do
     obj = mock('to_int')
     obj.should_receive(:to_int).and_return("5")
-    -> { [obj].pack("U") }.should raise_error(TypeError)
+    -> { [obj].pack("U") }.should.raise(TypeError)
   end
 
-  it "ignores NULL bytes between directives" do
-    [1, 2, 3].pack("U\x00U").should == "\x01\x02"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [1, 2, 3].pack("U\x00U")
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -76,11 +78,11 @@ describe :array_pack_unicode, shared: true do
   end
 
   it "raises a RangeError if passed a negative number" do
-    -> { [-1].pack("U") }.should raise_error(RangeError)
+    -> { [-1].pack("U") }.should.raise(RangeError)
   end
 
   it "raises a RangeError if passed a number larger than an unsigned 32-bit integer" do
-    -> { [2**32].pack("U") }.should raise_error(RangeError)
+    -> { [2**32].pack("U") }.should.raise(RangeError)
   end
 
   it "sets the output string to UTF-8 encoding" do
diff --git a/spec/ruby/core/array/pack/u_spec.rb b/spec/ruby/core/array/pack/u_spec.rb
index fe969cbb2d..c6a0d77eb2 100644
--- a/spec/ruby/core/array/pack/u_spec.rb
+++ b/spec/ruby/core/array/pack/u_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -18,6 +18,16 @@ describe "Array#pack with format 'u'" do
   it_behaves_like :array_pack_arguments, 'u'
   it_behaves_like :array_pack_taint, 'u'
 
+  it "calls #to_str to convert an Object to a String" do
+    obj = mock("pack u string")
+    obj.should_receive(:to_str).and_return("``abcdef")
+    [obj].pack("u*").should == "(8&!A8F-D968`\n"
+  end
+
+  it "will not implicitly convert a number to a string" do
+    -> { [0].pack('u') }.should.raise(TypeError)
+  end
+
   it "encodes an empty string as an empty string" do
     [""].pack("u").should == ""
   end
@@ -112,16 +122,16 @@ describe "Array#pack with format 'u'" do
 
   it "raises a TypeError if #to_str does not return a String" do
     obj = mock("pack m non-string")
-    -> { [obj].pack("u") }.should raise_error(TypeError)
+    -> { [obj].pack("u") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
-    -> { [nil].pack("u") }.should raise_error(TypeError)
+    -> { [nil].pack("u") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an Integer" do
-    -> { [0].pack("u") }.should raise_error(TypeError)
-    -> { [bignum_value].pack("u") }.should raise_error(TypeError)
+    -> { [0].pack("u") }.should.raise(TypeError)
+    -> { [bignum_value].pack("u") }.should.raise(TypeError)
   end
 
   it "sets the output string to US-ASCII encoding" do
diff --git a/spec/ruby/core/array/pack/w_spec.rb b/spec/ruby/core/array/pack/w_spec.rb
index 439fa02198..263e2a2288 100644
--- a/spec/ruby/core/array/pack/w_spec.rb
+++ b/spec/ruby/core/array/pack/w_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -24,8 +24,10 @@ describe "Array#pack with format 'w'" do
     [obj].pack("w").should == "\x05"
   end
 
-  it "ignores NULL bytes between directives" do
-    [1, 2, 3].pack("w\x00w").should == "\x01\x02"
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      [1, 2, 3].pack("w\x00w")
+    }.should.raise(ArgumentError, /unknown pack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -33,7 +35,7 @@ describe "Array#pack with format 'w'" do
   end
 
   it "raises an ArgumentError when passed a negative value" do
-    -> { [-1].pack("w") }.should raise_error(ArgumentError)
+    -> { [-1].pack("w") }.should.raise(ArgumentError)
   end
 
   it "returns a binary string" do
diff --git a/spec/ruby/core/array/pack/x_spec.rb b/spec/ruby/core/array/pack/x_spec.rb
index a28dd0bf21..7ff587a01e 100644
--- a/spec/ruby/core/array/pack/x_spec.rb
+++ b/spec/ruby/core/array/pack/x_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -30,6 +30,7 @@ describe "Array#pack with format 'x'" do
 
   it "does not add a NULL byte when passed the '*' modifier" do
     [].pack("x*").should == ""
+    [1, 2].pack("Cx*C").should == "\x01\x02"
   end
 end
 
@@ -55,10 +56,10 @@ describe "Array#pack with format 'X'" do
   end
 
   it "raises an ArgumentError if the output string is empty" do
-    -> { [1, 2, 3].pack("XC") }.should raise_error(ArgumentError)
+    -> { [1, 2, 3].pack("XC") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the count modifier is greater than the bytes in the string" do
-    -> { [1, 2, 3].pack("C2X3") }.should raise_error(ArgumentError)
+    -> { [1, 2, 3].pack("C2X3") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/array/pack/z_spec.rb b/spec/ruby/core/array/pack/z_spec.rb
index 82ce7b4a1c..5cd084c825 100644
--- a/spec/ruby/core/array/pack/z_spec.rb
+++ b/spec/ruby/core/array/pack/z_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -12,11 +12,21 @@ describe "Array#pack with format 'Z'" do
   it_behaves_like :array_pack_string, 'Z'
   it_behaves_like :array_pack_taint, 'Z'
 
+  it "calls #to_str to convert an Object to a String" do
+    obj = mock("pack Z string")
+    obj.should_receive(:to_str).and_return("``abcdef")
+    [obj].pack("Z*").should == "``abcdef\x00"
+  end
+
+  it "will not implicitly convert a number to a string" do
+    -> { [0].pack('Z') }.should.raise(TypeError)
+  end
+
   it "adds all the bytes and appends a NULL byte when passed the '*' modifier" do
     ["abc"].pack("Z*").should == "abc\x00"
   end
 
-  it "padds the output with NULL bytes when the count exceeds the size of the String" do
+  it "pads the output with NULL bytes when the count exceeds the size of the String" do
     ["abc"].pack("Z6").should == "abc\x00\x00\x00"
   end
 
diff --git a/spec/ruby/core/array/partition_spec.rb b/spec/ruby/core/array/partition_spec.rb
index be36fffcab..bd3f3a6b6f 100644
--- a/spec/ruby/core/array/partition_spec.rb
+++ b/spec/ruby/core/array/partition_spec.rb
@@ -36,8 +36,8 @@ describe "Array#partition" do
 
   it "does not return subclass instances on Array subclasses" do
     result = ArraySpecs::MyArray[1, 2, 3].partition { |x| x % 2 == 0 }
-    result.should be_an_instance_of(Array)
-    result[0].should be_an_instance_of(Array)
-    result[1].should be_an_instance_of(Array)
+    result.should.instance_of?(Array)
+    result[0].should.instance_of?(Array)
+    result[1].should.instance_of?(Array)
   end
 end
diff --git a/spec/ruby/core/array/permutation_spec.rb b/spec/ruby/core/array/permutation_spec.rb
index f15bd76639..b5df84b52b 100644
--- a/spec/ruby/core/array/permutation_spec.rb
+++ b/spec/ruby/core/array/permutation_spec.rb
@@ -11,7 +11,7 @@ describe "Array#permutation" do
 
   it "returns an Enumerator of all permutations when called without a block or arguments" do
     enum = @numbers.permutation
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.sort.should == [
       [1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]
     ].sort
@@ -19,13 +19,13 @@ describe "Array#permutation" do
 
   it "returns an Enumerator of permutations of given length when called with an argument but no block" do
     enum = @numbers.permutation(1)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.sort.should == [[1],[2],[3]]
   end
 
   it "yields all permutations to the block then returns self when called with block but no arguments" do
     array = @numbers.permutation {|n| @yielded << n}
-    array.should be_an_instance_of(Array)
+    array.should.instance_of?(Array)
     array.sort.should == @numbers.sort
     @yielded.sort.should == [
       [1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]
@@ -34,7 +34,7 @@ describe "Array#permutation" do
 
   it "yields all permutations of given length to the block then returns self when called with block and argument" do
     array = @numbers.permutation(2) {|n| @yielded << n}
-    array.should be_an_instance_of(Array)
+    array.should.instance_of?(Array)
     array.sort.should == @numbers.sort
     @yielded.sort.should == [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]].sort
   end
@@ -78,7 +78,7 @@ describe "Array#permutation" do
        [3, 1],      [3, 2],      [3, [4, 5]],
       [[4, 5], 1], [[4, 5], 2], [[4, 5], 3]
     ]
-    expected.each {|e| got.include?(e).should be_true}
+    expected.each {|e| got.include?(e).should == true}
     got.size.should == expected.size
   end
 
diff --git a/spec/ruby/core/array/plus_spec.rb b/spec/ruby/core/array/plus_spec.rb
index 7692163980..7ead927fc0 100644
--- a/spec/ruby/core/array/plus_spec.rb
+++ b/spec/ruby/core/array/plus_spec.rb
@@ -14,10 +14,23 @@ describe "Array#+" do
     (ary + ary).should == [1, 2, 3, 1, 2, 3]
   end
 
-  it "tries to convert the passed argument to an Array using #to_ary" do
-    obj = mock('["x", "y"]')
-    obj.should_receive(:to_ary).and_return(["x", "y"])
-    ([1, 2, 3] + obj).should == [1, 2, 3, "x", "y"]
+  describe "converts the passed argument to an Array using #to_ary" do
+    it "successfully concatenates the resulting array from the #to_ary call" do
+      obj = mock('["x", "y"]')
+      obj.should_receive(:to_ary).and_return(["x", "y"])
+      ([1, 2, 3] + obj).should == [1, 2, 3, "x", "y"]
+    end
+
+    it "raises a TypeError if the given argument can't be converted to an array" do
+      -> { [1, 2, 3] + nil }.should.raise(TypeError)
+      -> { [1, 2, 3] + "abc" }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to an Array" do
+      obj = mock("hello")
+      obj.should_receive(:to_ary).and_raise(NoMethodError)
+      -> { [1, 2, 3] + obj }.should.raise(NoMethodError)
+    end
   end
 
   it "properly handles recursive arrays" do
@@ -32,26 +45,12 @@ describe "Array#+" do
   end
 
   it "does return subclass instances with Array subclasses" do
-    (ArraySpecs::MyArray[1, 2, 3] + []).should be_an_instance_of(Array)
-    (ArraySpecs::MyArray[1, 2, 3] + ArraySpecs::MyArray[]).should be_an_instance_of(Array)
-    ([1, 2, 3] + ArraySpecs::MyArray[]).should be_an_instance_of(Array)
+    (ArraySpecs::MyArray[1, 2, 3] + []).should.instance_of?(Array)
+    (ArraySpecs::MyArray[1, 2, 3] + ArraySpecs::MyArray[]).should.instance_of?(Array)
+    ([1, 2, 3] + ArraySpecs::MyArray[]).should.instance_of?(Array)
   end
 
   it "does not call to_ary on array subclasses" do
     ([5, 6] + ArraySpecs::ToAryArray[1, 2]).should == [5, 6, 1, 2]
   end
-
-  it "does not get infected even if an original array is tainted" do
-    ([1, 2] + [3, 4]).tainted?.should be_false
-    ([1, 2].taint + [3, 4]).tainted?.should be_false
-    ([1, 2] + [3, 4].taint).tainted?.should be_false
-    ([1, 2].taint + [3, 4].taint).tainted?.should be_false
-  end
-
-  it "does not infected even if an original array is untrusted" do
-    ([1, 2] + [3, 4]).untrusted?.should be_false
-    ([1, 2].untrust + [3, 4]).untrusted?.should be_false
-    ([1, 2] + [3, 4].untrust).untrusted?.should be_false
-    ([1, 2].untrust + [3, 4].untrust).untrusted?.should be_false
-  end
 end
diff --git a/spec/ruby/core/array/pop_spec.rb b/spec/ruby/core/array/pop_spec.rb
index 7dbd6cb3cc..069083331c 100644
--- a/spec/ruby/core/array/pop_spec.rb
+++ b/spec/ruby/core/array/pop_spec.rb
@@ -30,28 +30,12 @@ describe "Array#pop" do
     array.pop.should == [1, 'two', 3.0, array, array, array, array]
   end
 
-  it "keeps taint status" do
-    a = [1, 2].taint
-    a.pop
-    a.tainted?.should be_true
-    a.pop
-    a.tainted?.should be_true
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.pop }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.pop }.should raise_error(frozen_error_class)
-  end
-
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.pop }.should raise_error(frozen_error_class)
-  end
-
-  it "keeps untrusted status" do
-    a = [1, 2].untrust
-    a.pop
-    a.untrusted?.should be_true
-    a.pop
-    a.untrusted?.should be_true
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.pop }.should.raise(FrozenError)
   end
 
   describe "passed a number n as an argument" do
@@ -87,7 +71,7 @@ describe "Array#pop" do
       popped2.should == []
       a.should == []
 
-      popped1.should_not equal(popped2)
+      popped1.should_not.equal?(popped2)
     end
 
     it "returns whole elements if n exceeds size of the array" do
@@ -98,14 +82,14 @@ describe "Array#pop" do
 
     it "does not return self even when it returns whole elements" do
       a = [1, 2, 3, 4, 5]
-      a.pop(5).should_not equal(a)
+      a.pop(5).should_not.equal?(a)
 
       a = [1, 2, 3, 4, 5]
-      a.pop(6).should_not equal(a)
+      a.pop(6).should_not.equal?(a)
     end
 
     it "raises an ArgumentError if n is negative" do
-      ->{ [1, 2, 3].pop(-1) }.should raise_error(ArgumentError)
+      ->{ [1, 2, 3].pop(-1) }.should.raise(ArgumentError)
     end
 
     it "tries to convert n to an Integer using #to_int" do
@@ -120,49 +104,21 @@ describe "Array#pop" do
     end
 
     it "raises a TypeError when the passed n cannot be coerced to Integer" do
-      ->{ [1, 2].pop("cat") }.should raise_error(TypeError)
-      ->{ [1, 2].pop(nil) }.should raise_error(TypeError)
+      ->{ [1, 2].pop("cat") }.should.raise(TypeError)
+      ->{ [1, 2].pop(nil) }.should.raise(TypeError)
     end
 
     it "raises an ArgumentError if more arguments are passed" do
-      ->{ [1, 2].pop(1, 2) }.should raise_error(ArgumentError)
+      ->{ [1, 2].pop(1, 2) }.should.raise(ArgumentError)
     end
 
     it "does not return subclass instances with Array subclass" do
-      ArraySpecs::MyArray[1, 2, 3].pop(2).should be_an_instance_of(Array)
-    end
-
-    it "returns an untainted array even if the array is tainted" do
-      ary = [1, 2].taint
-      ary.pop(2).tainted?.should be_false
-      ary.pop(0).tainted?.should be_false
-    end
-
-    it "keeps taint status" do
-      a = [1, 2].taint
-      a.pop(2)
-      a.tainted?.should be_true
-      a.pop(2)
-      a.tainted?.should be_true
-    end
-
-    it "returns a trusted array even if the array is untrusted" do
-      ary = [1, 2].untrust
-      ary.pop(2).untrusted?.should be_false
-      ary.pop(0).untrusted?.should be_false
-    end
-
-    it "raises a #{frozen_error_class} on a frozen array" do
-      -> { ArraySpecs.frozen_array.pop(2) }.should raise_error(frozen_error_class)
-      -> { ArraySpecs.frozen_array.pop(0) }.should raise_error(frozen_error_class)
+      ArraySpecs::MyArray[1, 2, 3].pop(2).should.instance_of?(Array)
     end
 
-    it "keeps untrusted status" do
-      a = [1, 2].untrust
-      a.pop(2)
-      a.untrusted?.should be_true
-      a.pop(2)
-      a.untrusted?.should be_true
+    it "raises a FrozenError on a frozen array" do
+      -> { ArraySpecs.frozen_array.pop(2) }.should.raise(FrozenError)
+      -> { ArraySpecs.frozen_array.pop(0) }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/array/prepend_spec.rb b/spec/ruby/core/array/prepend_spec.rb
index 22230ec300..2d0ce31c71 100644
--- a/spec/ruby/core/array/prepend_spec.rb
+++ b/spec/ruby/core/array/prepend_spec.rb
@@ -1,9 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/unshift'
 
-ruby_version_is "2.5" do
-  describe "Array#prepend" do
-    it_behaves_like :array_unshift, :prepend
+describe "Array#prepend" do
+  it "is an alias of Array#unshift" do
+    Array.instance_method(:prepend).should == Array.instance_method(:unshift)
   end
 end
diff --git a/spec/ruby/core/array/product_spec.rb b/spec/ruby/core/array/product_spec.rb
index 07d2880a96..837f0eaf34 100644
--- a/spec/ruby/core/array/product_spec.rb
+++ b/spec/ruby/core/array/product_spec.rb
@@ -3,12 +3,17 @@ require_relative 'fixtures/classes'
 
 describe "Array#product" do
   it "returns converted arguments using :to_ary" do
-    ->{ [1].product(2..3) }.should raise_error(TypeError)
+    ->{ [1].product(2..3) }.should.raise(TypeError)
     ar = ArraySpecs::ArrayConvertible.new(2,3)
     [1].product(ar).should == [[1,2],[1,3]]
     ar.called.should == :to_ary
   end
 
+  it "returns converted arguments using :method_missing" do
+    ar = ArraySpecs::ArrayMethodMissing.new(2,3)
+    [1].product(ar).should == [[1,2],[1,3]]
+  end
+
   it "returns the expected result" do
     [1,2].product([3,4,5],[6,8]).should == [[1, 3, 6], [1, 3, 8], [1, 4, 6], [1, 4, 8], [1, 5, 6], [1, 5, 8],
                                             [2, 3, 6], [2, 3, 8], [2, 4, 6], [2, 4, 8], [2, 5, 6], [2, 5, 8]]
@@ -26,7 +31,7 @@ describe "Array#product" do
     a = (0..100).to_a
     -> do
       a.product(a, a, a, a, a, a, a, a, a, a)
-    end.should raise_error(RangeError)
+    end.should.raise(RangeError)
   end
 
   describe "when given a block" do
@@ -38,7 +43,7 @@ describe "Array#product" do
 
       acc = []
       [1,2].product([3,4,5],[],[6,8]){|array| acc << array}
-      acc.should be_empty
+      acc.should.empty?
     end
 
     it "returns self" do
@@ -51,18 +56,18 @@ describe "Array#product" do
       a = (0..100).to_a
       -> do
         a.product(a, a, a, a, a, a, a, a, a, a)
-      end.should raise_error(RangeError)
+      end.should.raise(RangeError)
     end
   end
 
   describe "when given an empty block" do
     it "returns self" do
       arr = [1,2]
-      arr.product([3,4,5],[6,8]){}.should equal(arr)
+      arr.product([3,4,5],[6,8]){}.should.equal?(arr)
       arr = []
-      arr.product([3,4,5],[6,8]){}.should equal(arr)
+      arr.product([3,4,5],[6,8]){}.should.equal?(arr)
       arr = [1,2]
-      arr.product([]){}.should equal(arr)
+      arr.product([]){}.should.equal?(arr)
     end
   end
 end
diff --git a/spec/ruby/core/array/push_spec.rb b/spec/ruby/core/array/push_spec.rb
index 607cbc7b4d..6255a84371 100644
--- a/spec/ruby/core/array/push_spec.rb
+++ b/spec/ruby/core/array/push_spec.rb
@@ -1,7 +1,36 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/push'
 
 describe "Array#push" do
-  it_behaves_like :array_push, :push
+  it "appends the arguments to the array" do
+    a = [ "a", "b", "c" ]
+    a.push("d", "e", "f").should.equal?(a)
+    a.push.should == ["a", "b", "c", "d", "e", "f"]
+    a.push(5)
+    a.should == ["a", "b", "c", "d", "e", "f", 5]
+
+    a = [0, 1]
+    a.push(2)
+    a.should == [0, 1, 2]
+  end
+
+  it "isn't confused by previous shift" do
+    a = [ "a", "b", "c" ]
+    a.shift
+    a.push("foo")
+    a.should == ["b", "c", "foo"]
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.push(:last).should == [empty, :last]
+
+    array = ArraySpecs.recursive_array
+    array.push(:last).should == [1, 'two', 3.0, array, array, array, array, array, :last]
+  end
+
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.push(1) }.should.raise(FrozenError)
+    -> { ArraySpecs.frozen_array.push }.should.raise(FrozenError)
+  end
 end
diff --git a/spec/ruby/core/array/rassoc_spec.rb b/spec/ruby/core/array/rassoc_spec.rb
index 62fbd40611..95e4ed1892 100644
--- a/spec/ruby/core/array/rassoc_spec.rb
+++ b/spec/ruby/core/array/rassoc_spec.rb
@@ -12,11 +12,11 @@ describe "Array#rassoc" do
 
   it "properly handles recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
-    empty.rassoc([]).should be_nil
+    empty.rassoc([]).should == nil
     [[empty, empty]].rassoc(empty).should == [empty, empty]
 
     array = ArraySpecs.recursive_array
-    array.rassoc(array).should be_nil
+    array.rassoc(array).should == nil
     [[empty, array]].rassoc(array).should == [empty, array]
   end
 
@@ -35,4 +35,16 @@ describe "Array#rassoc" do
 
     [[1, :foobar, o], [2, o, 1], [3, mock('foo')]].rassoc(key).should == [2, o, 1]
   end
+
+  it "calls to_ary on non-array elements" do
+    s1 = [1, 2]
+    s2 = ArraySpecs::ArrayConvertible.new(2, 3)
+    a = [s1, s2]
+
+    s1.should_not_receive(:to_ary)
+    a.rassoc(2).should.equal?(s1)
+
+    a.rassoc(3).should == [2, 3]
+    s2.called.should.equal?(:to_ary)
+  end
 end
diff --git a/spec/ruby/core/array/reject_spec.rb b/spec/ruby/core/array/reject_spec.rb
index 1e9c296c8d..8d237b3a75 100644
--- a/spec/ruby/core/array/reject_spec.rb
+++ b/spec/ruby/core/array/reject_spec.rb
@@ -2,6 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/enumeratorize'
 require_relative 'shared/delete_if'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Array#reject" do
@@ -9,9 +10,9 @@ describe "Array#reject" do
     ary = [1, 2, 3, 4, 5]
     ary.reject { true }.should == []
     ary.reject { false }.should == ary
-    ary.reject { false }.should_not equal ary
+    ary.reject { false }.should_not.equal? ary
     ary.reject { nil }.should == ary
-    ary.reject { nil }.should_not equal ary
+    ary.reject { nil }.should_not.equal? ary
     ary.reject { 5 }.should == []
     ary.reject { |i| i < 3 }.should == [3, 4, 5]
     ary.reject { |i| i % 2 == 0 }.should == [1, 3, 5]
@@ -34,7 +35,7 @@ describe "Array#reject" do
   end
 
   it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].reject { |x| x % 2 == 0 }.should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].reject { |x| x % 2 == 0 }.should.instance_of?(Array)
   end
 
   it "does not retain instance variables" do
@@ -47,10 +48,14 @@ describe "Array#reject" do
   it_behaves_like :enumeratorized_with_origin_size, :reject, [1,2,3]
 end
 
+describe "Array#reject" do
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :reject
+end
+
 describe "Array#reject!" do
   it "removes elements for which block is true" do
     a = [3, 4, 5, 6, 7, 8, 9, 10, 11]
-    a.reject! { |i| i % 2 == 0 }.should equal(a)
+    a.reject! { |i| i % 2 == 0 }.should.equal?(a)
     a.should == [3, 5, 7, 9, 11]
     a.reject! { |i| i > 8 }
     a.should == [3, 5, 7]
@@ -100,15 +105,20 @@ describe "Array#reject!" do
   end
 
   it "returns an Enumerator if no block given, and the array is frozen" do
-    ArraySpecs.frozen_array.reject!.should be_an_instance_of(Enumerator)
+    ArraySpecs.frozen_array.reject!.should.instance_of?(Enumerator)
+  end
+
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.reject! {} }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.reject! {} }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.reject! {} }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.reject! {} }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+    enum = ArraySpecs.frozen_array.reject!
+    -> { enum.each {} }.should.raise(FrozenError)
   end
 
   it "does not truncate the array is the block raises an exception" do
@@ -141,3 +151,8 @@ describe "Array#reject!" do
   it_behaves_like :enumeratorized_with_origin_size, :reject!, [1,2,3]
   it_behaves_like :delete_if, :reject!
 end
+
+describe "Array#reject!" do
+  @value_to_return = -> _ { false }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :reject!
+end
diff --git a/spec/ruby/core/array/repeated_combination_spec.rb b/spec/ruby/core/array/repeated_combination_spec.rb
index b62382024a..a714f05f54 100644
--- a/spec/ruby/core/array/repeated_combination_spec.rb
+++ b/spec/ruby/core/array/repeated_combination_spec.rb
@@ -6,16 +6,16 @@ describe "Array#repeated_combination" do
   end
 
   it "returns an enumerator when no block is provided" do
-    @array.repeated_combination(2).should be_an_instance_of(Enumerator)
+    @array.repeated_combination(2).should.instance_of?(Enumerator)
   end
 
   it "returns self when a block is given" do
-    @array.repeated_combination(2){}.should equal(@array)
+    @array.repeated_combination(2){}.should.equal?(@array)
   end
 
   it "yields nothing for negative length and return self" do
-    @array.repeated_combination(-1){ fail }.should equal(@array)
-    @array.repeated_combination(-10){ fail }.should equal(@array)
+    @array.repeated_combination(-1){ fail }.should.equal?(@array)
+    @array.repeated_combination(-10){ fail }.should.equal?(@array)
   end
 
   it "yields the expected repeated_combinations" do
diff --git a/spec/ruby/core/array/repeated_permutation_spec.rb b/spec/ruby/core/array/repeated_permutation_spec.rb
index a165fda09e..c54a8c0c2b 100644
--- a/spec/ruby/core/array/repeated_permutation_spec.rb
+++ b/spec/ruby/core/array/repeated_permutation_spec.rb
@@ -10,13 +10,13 @@ describe "Array#repeated_permutation" do
 
   it "returns an Enumerator of all repeated permutations of given length when called without a block" do
     enum = @numbers.repeated_permutation(2)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.sort.should == @permutations
   end
 
   it "yields all repeated_permutations to the block then returns self when called with block but no arguments" do
     yielded = []
-    @numbers.repeated_permutation(2) {|n| yielded << n}.should equal(@numbers)
+    @numbers.repeated_permutation(2) {|n| yielded << n}.should.equal?(@numbers)
     yielded.sort.should == @permutations
   end
 
diff --git a/spec/ruby/core/array/replace_spec.rb b/spec/ruby/core/array/replace_spec.rb
index 2f53338f5e..ee6a98a646 100644
--- a/spec/ruby/core/array/replace_spec.rb
+++ b/spec/ruby/core/array/replace_spec.rb
@@ -1,7 +1,63 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/replace'
 
 describe "Array#replace" do
-  it_behaves_like :array_replace, :replace
+  it "replaces the elements with elements from other array" do
+    a = [1, 2, 3, 4, 5]
+    b = ['a', 'b', 'c']
+    a.replace(b).should.equal?(a)
+    a.should == b
+    a.should_not.equal?(b)
+
+    a.replace([4] * 10)
+    a.should == [4] * 10
+
+    a.replace([])
+    a.should == []
+  end
+
+  it "properly handles recursive arrays" do
+    orig = [1, 2, 3]
+    empty = ArraySpecs.empty_recursive_array
+    orig.replace(empty)
+    orig.should == empty
+
+    array = ArraySpecs.recursive_array
+    orig.replace(array)
+    orig.should == array
+  end
+
+  it "returns self" do
+    ary = [1, 2, 3]
+    other = [:a, :b, :c]
+    ary.replace(other).should.equal?(ary)
+  end
+
+  it "does not make self dependent to the original array" do
+    ary = [1, 2, 3]
+    other = [:a, :b, :c]
+    ary.replace(other)
+    ary.should == [:a, :b, :c]
+    ary << :d
+    ary.should == [:a, :b, :c, :d]
+    other.should == [:a, :b, :c]
+  end
+
+  it "tries to convert the passed argument to an Array using #to_ary" do
+    obj = mock('to_ary')
+    obj.stub!(:to_ary).and_return([1, 2, 3])
+    [].replace(obj).should == [1, 2, 3]
+  end
+
+  it "does not call #to_ary on Array subclasses" do
+    obj = ArraySpecs::ToAryArray[5, 6, 7]
+    obj.should_not_receive(:to_ary)
+    [].replace(ArraySpecs::ToAryArray[5, 6, 7]).should == [5, 6, 7]
+  end
+
+  it "raises a FrozenError on a frozen array" do
+    -> {
+      ArraySpecs.frozen_array.replace(ArraySpecs.frozen_array)
+    }.should.raise(FrozenError)
+  end
 end
diff --git a/spec/ruby/core/array/reverse_each_spec.rb b/spec/ruby/core/array/reverse_each_spec.rb
index 28b8bfcb34..8fa5ce6da1 100644
--- a/spec/ruby/core/array/reverse_each_spec.rb
+++ b/spec/ruby/core/array/reverse_each_spec.rb
@@ -5,7 +5,7 @@ require_relative '../enumerable/shared/enumeratorized'
 
 # Modifying a collection while the contents are being iterated
 # gives undefined behavior. See
-# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/23633
+# https://blade.ruby-lang.org/ruby-core/23633
 
 describe "Array#reverse_each" do
   before :each do
@@ -19,7 +19,7 @@ describe "Array#reverse_each" do
 
   it "returns self" do
     a = [:a, :b, :c]
-    a.reverse_each { |x| }.should equal(a)
+    a.reverse_each { |x| }.should.equal?(a)
   end
 
   it "yields only the top level element of an empty recursive arrays" do
@@ -38,6 +38,20 @@ describe "Array#reverse_each" do
     [1, 2, 3].reverse_each.size.should == 3
   end
 
+  it "tolerates increasing an array size during iteration" do
+    array = [:a, :b, :c]
+    ScratchPad.record []
+    i = 0
+
+    array.reverse_each do |e|
+      ScratchPad << e
+      array.prepend i if i < 100
+      i += 1
+    end
+
+    ScratchPad.recorded.should == [:c, :a, 1]
+  end
+
   it_behaves_like :enumeratorize, :reverse_each
   it_behaves_like :enumeratorized_with_origin_size, :reverse_each, [1,2,3]
 end
diff --git a/spec/ruby/core/array/reverse_spec.rb b/spec/ruby/core/array/reverse_spec.rb
index e738be6fe7..f25a484be8 100644
--- a/spec/ruby/core/array/reverse_spec.rb
+++ b/spec/ruby/core/array/reverse_spec.rb
@@ -16,14 +16,14 @@ describe "Array#reverse" do
   end
 
   it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].reverse.should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].reverse.should.instance_of?(Array)
   end
 end
 
 describe "Array#reverse!" do
   it "reverses the elements in place" do
     a = [6, 3, 4, 2, 1]
-    a.reverse!.should equal(a)
+    a.reverse!.should.equal?(a)
     a.should == [1, 2, 4, 3, 6]
     [].reverse!.should == []
   end
@@ -36,7 +36,7 @@ describe "Array#reverse!" do
     array.reverse!.should == [array, array, array, array, array, 3.0, 'two', 1]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.reverse! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.reverse! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/rindex_spec.rb b/spec/ruby/core/array/rindex_spec.rb
index 175c7bcfe2..858c39dc92 100644
--- a/spec/ruby/core/array/rindex_spec.rb
+++ b/spec/ruby/core/array/rindex_spec.rb
@@ -4,7 +4,7 @@ require_relative '../enumerable/shared/enumeratorized'
 
 # Modifying a collection while the contents are being iterated
 # gives undefined behavior. See
-# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/23633
+# https://blade.ruby-lang.org/ruby-core/23633
 
 describe "Array#rindex" do
   it "returns the first index backwards from the end where element == to object" do
@@ -41,7 +41,7 @@ describe "Array#rindex" do
   it "properly handles empty recursive arrays" do
     empty = ArraySpecs.empty_recursive_array
     empty.rindex(empty).should == 0
-    empty.rindex(1).should be_nil
+    empty.rindex(1).should == nil
   end
 
   it "properly handles recursive arrays" do
@@ -68,10 +68,25 @@ describe "Array#rindex" do
     seen.should == [3]
   end
 
+  it "tolerates increasing an array size during iteration" do
+    array = [:a, :b, :c]
+    ScratchPad.record []
+    i = 0
+
+    array.rindex do |e|
+      ScratchPad << e
+      array.prepend i if i < 100
+      i += 1
+      false
+    end
+
+    ScratchPad.recorded.should == [:c, :a, 1]
+  end
+
   describe "given no argument and no block" do
     it "produces an Enumerator" do
       enum = [4, 2, 1, 5, 1, 3].rindex
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.each { |x| x < 2 }.should == 4
     end
   end
diff --git a/spec/ruby/core/array/rotate_spec.rb b/spec/ruby/core/array/rotate_spec.rb
index cc1aabf986..009ce5ed49 100644
--- a/spec/ruby/core/array/rotate_spec.rb
+++ b/spec/ruby/core/array/rotate_spec.rb
@@ -29,10 +29,10 @@ describe "Array#rotate" do
     it "raises a TypeError if not passed an integer-like argument" do
       -> {
         [1, 2].rotate(nil)
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
       -> {
         [1, 2].rotate("4")
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 
@@ -50,18 +50,18 @@ describe "Array#rotate" do
       [].freeze.rotate
       [2].freeze.rotate(2)
       [1,2,3].freeze.rotate(-3)
-    }.should_not raise_error
+    }.should_not.raise
   end
 
   it "does not return self" do
     a = [1, 2, 3]
-    a.rotate.should_not equal(a)
+    a.rotate.should_not.equal?(a)
     a = []
-    a.rotate(0).should_not equal(a)
+    a.rotate(0).should_not.equal?(a)
   end
 
   it "does not return subclass instance for Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].rotate.should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].rotate.should.instance_of?(Array)
   end
 end
 
@@ -69,7 +69,7 @@ describe "Array#rotate!" do
   describe "when passed no argument" do
     it "moves the first element to the end and returns self" do
       a = [1, 2, 3, 4, 5]
-      a.rotate!.should equal(a)
+      a.rotate!.should.equal?(a)
       a.should == [2, 3, 4, 5, 1]
     end
   end
@@ -77,11 +77,11 @@ describe "Array#rotate!" do
   describe "with an argument n" do
     it "moves the first (n % size) elements at the end and returns self" do
       a = [1, 2, 3, 4, 5]
-      a.rotate!(2).should equal(a)
+      a.rotate!(2).should.equal?(a)
       a.should == [3, 4, 5, 1, 2]
-      a.rotate!(-12).should equal(a)
+      a.rotate!(-12).should.equal?(a)
       a.should == [1, 2, 3, 4, 5]
-      a.rotate!(13).should equal(a)
+      a.rotate!(13).should.equal?(a)
       a.should == [4, 5, 1, 2, 3]
     end
 
@@ -96,34 +96,34 @@ describe "Array#rotate!" do
     it "raises a TypeError if not passed an integer-like argument" do
       -> {
         [1, 2].rotate!(nil)
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
       -> {
         [1, 2].rotate!("4")
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 
   it "does nothing and returns self when the length is zero or one" do
     a = [1]
-    a.rotate!.should equal(a)
+    a.rotate!.should.equal?(a)
     a.should == [1]
-    a.rotate!(2).should equal(a)
+    a.rotate!(2).should.equal?(a)
     a.should == [1]
-    a.rotate!(-21).should equal(a)
+    a.rotate!(-21).should.equal?(a)
     a.should == [1]
 
     a = []
-    a.rotate!.should equal(a)
+    a.rotate!.should.equal?(a)
     a.should == []
-    a.rotate!(2).should equal(a)
+    a.rotate!(2).should.equal?(a)
     a.should == []
-    a.rotate!(-21).should equal(a)
+    a.rotate!(-21).should.equal?(a)
     a.should == []
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { [1, 2, 3].freeze.rotate!(0) }.should raise_error(frozen_error_class)
-    -> { [1].freeze.rotate!(42) }.should raise_error(frozen_error_class)
-    -> { [].freeze.rotate! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { [1, 2, 3].freeze.rotate!(0) }.should.raise(FrozenError)
+    -> { [1].freeze.rotate!(42) }.should.raise(FrozenError)
+    -> { [].freeze.rotate! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/array/sample_spec.rb b/spec/ruby/core/array/sample_spec.rb
index 44be91ba18..fd443b47de 100644
--- a/spec/ruby/core/array/sample_spec.rb
+++ b/spec/ruby/core/array/sample_spec.rb
@@ -3,24 +3,34 @@ require_relative 'fixtures/classes'
 
 describe "Array#sample" do
   it "samples evenly" do
-    ary = [0, 1, 2, 3]
-    3.times do |i|
-      counts = [0, 0, 0, 0]
-      4000.times do
-        counts[ary.sample(3)[i]] += 1
-      end
-      counts.each do |count|
-        (800..1200).should include(count)
-      end
-    end
+    ArraySpecs.measure_sample_fairness(4, 1, 400)
+    ArraySpecs.measure_sample_fairness(4, 2, 400)
+    ArraySpecs.measure_sample_fairness(4, 3, 400)
+    ArraySpecs.measure_sample_fairness(40, 3, 400)
+    ArraySpecs.measure_sample_fairness(40, 4, 400)
+    ArraySpecs.measure_sample_fairness(40, 8, 400)
+    ArraySpecs.measure_sample_fairness(40, 16, 400)
+    ArraySpecs.measure_sample_fairness_large_sample_size(100, 80, 4000)
   end
 
   it "returns nil for an empty Array" do
-    [].sample.should be_nil
+    [].sample.should == nil
+  end
+
+  it "returns nil for an empty array when called without n and a Random is given" do
+    [].sample(random: Random.new(42)).should == nil
   end
 
   it "returns a single value when not passed a count" do
-    [4].sample.should equal(4)
+    [4].sample.should.equal?(4)
+  end
+
+  it "returns a single value when not passed a count and a Random is given" do
+    [4].sample(random: Random.new(42)).should.equal?(4)
+  end
+
+  it "returns a single value when not passed a count and a Random class is given" do
+    [4].sample(random: Random).should.equal?(4)
   end
 
   it "returns an empty Array when passed zero" do
@@ -28,12 +38,12 @@ describe "Array#sample" do
   end
 
   it "returns an Array of elements when passed a count" do
-    [1, 2, 3, 4].sample(3).should be_an_instance_of(Array)
+    [1, 2, 3, 4].sample(3).should.instance_of?(Array)
   end
 
   it "returns elements from the Array" do
     array = [1, 2, 3, 4]
-    array.sample(3).all? { |x| array.should include(x) }
+    array.sample(3).all? { |x| array.should.include?(x) }
   end
 
   it "returns at most the number of elements in the Array" do
@@ -57,46 +67,29 @@ describe "Array#sample" do
   end
 
   it "raises ArgumentError when passed a negative count" do
-    -> { [1, 2].sample(-1) }.should raise_error(ArgumentError)
+    -> { [1, 2].sample(-1) }.should.raise(ArgumentError)
   end
 
   it "does not return subclass instances with Array subclass" do
-    ArraySpecs::MyArray[1, 2, 3].sample(2).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].sample(2).should.instance_of?(Array)
   end
 
   describe "with options" do
-    it "calls #to_hash to convert the passed Object" do
-      obj = mock("array_sample")
-      obj.should_receive(:to_hash).and_return({})
-      obj.should_not_receive(:to_int)
-
-      [1, 2].sample(obj).should be_an_instance_of(Fixnum)
-    end
-
-    it "calls #to_int on the first argument and #to_hash on the second when passed Objects" do
-      count = mock("array_sample_count")
-      count.should_receive(:to_int).and_return(2)
-      options = mock("array_sample_options")
-      options.should_receive(:to_hash).and_return({})
-
-      [1, 2].sample(count, options).size.should == 2
-    end
-
     it "calls #rand on the Object passed by the :random key in the arguments Hash" do
       obj = mock("array_sample_random")
       obj.should_receive(:rand).and_return(0.5)
 
-      [1, 2].sample(random: obj).should be_an_instance_of(Fixnum)
+      [1, 2].sample(random: obj).should.instance_of?(Integer)
     end
 
     it "raises a NoMethodError if an object passed for the RNG does not define #rand" do
       obj = BasicObject.new
 
-      -> { [1, 2].sample(random: obj) }.should raise_error(NoMethodError)
+      -> { [1, 2].sample(random: obj) }.should.raise(NoMethodError)
     end
 
-    describe "when the object returned by #rand is a Fixnum" do
-      it "uses the fixnum as index" do
+    describe "when the object returned by #rand is an Integer" do
+      it "uses the integer as index" do
         random = mock("array_sample_random_ret")
         random.should_receive(:rand).and_return(0)
 
@@ -112,19 +105,26 @@ describe "Array#sample" do
         random = mock("array_sample_random")
         random.should_receive(:rand).and_return(-1)
 
-        -> { [1, 2].sample(random: random) }.should raise_error(RangeError)
+        -> { [1, 2].sample(random: random) }.should.raise(RangeError)
       end
 
       it "raises a RangeError if the value is equal to the Array size" do
         random = mock("array_sample_random")
         random.should_receive(:rand).and_return(2)
 
-        -> { [1, 2].sample(random: random) }.should raise_error(RangeError)
+        -> { [1, 2].sample(random: random) }.should.raise(RangeError)
+      end
+
+      it "raises a RangeError if the value is greater than the Array size" do
+        random = mock("array_sample_random")
+        random.should_receive(:rand).and_return(3)
+
+        -> { [1, 2].sample(random: random) }.should.raise(RangeError)
       end
     end
   end
 
-  describe "when the object returned by #rand is not a Fixnum but responds to #to_int" do
+  describe "when the object returned by #rand is not an Integer but responds to #to_int" do
     it "calls #to_int on the Object" do
       value = mock("array_sample_random_value")
       value.should_receive(:to_int).and_return(1)
@@ -140,7 +140,7 @@ describe "Array#sample" do
       random = mock("array_sample_random")
       random.should_receive(:rand).and_return(value)
 
-      -> { [1, 2].sample(random: random) }.should raise_error(RangeError)
+      -> { [1, 2].sample(random: random) }.should.raise(RangeError)
     end
 
     it "raises a RangeError if the value is equal to the Array size" do
@@ -149,7 +149,7 @@ describe "Array#sample" do
       random = mock("array_sample_random")
       random.should_receive(:rand).and_return(value)
 
-      -> { [1, 2].sample(random: random) }.should raise_error(RangeError)
+      -> { [1, 2].sample(random: random) }.should.raise(RangeError)
     end
   end
 end
diff --git a/spec/ruby/core/array/select_spec.rb b/spec/ruby/core/array/select_spec.rb
index 298b591744..57ec0b2540 100644
--- a/spec/ruby/core/array/select_spec.rb
+++ b/spec/ruby/core/array/select_spec.rb
@@ -1,13 +1,42 @@
 require_relative '../../spec_helper'
-require_relative 'shared/select'
+require_relative '../enumerable/shared/enumeratorized'
+require_relative 'fixtures/classes'
+require_relative 'shared/enumeratorize'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
+require_relative 'shared/keep_if'
 
 describe "Array#select" do
-  it_behaves_like :array_select, :select
+  it_behaves_like :enumeratorize, :select
+
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :select
+
+  before :each do
+    @object = [1,2,3]
+  end
+  it_behaves_like :enumeratorized_with_origin_size, :select
+
+  it "returns a new array of elements for which block is true" do
+    [1, 3, 4, 5, 6, 9].select { |i| i % ((i + 1) / 2) == 0}.should == [1, 4, 6]
+  end
+
+  it "does not return subclass instance on Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].select { true }.should.instance_of?(Array)
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.select { true }.should == empty
+    empty.select { false }.should == []
+
+    array = ArraySpecs.recursive_array
+    array.select { true }.should == [1, 'two', 3.0, array, array, array, array, array]
+    array.select { false }.should == []
+  end
 end
 
 describe "Array#select!" do
   it "returns nil if no changes were made in the array" do
-    [1, 2, 3].select! { true }.should be_nil
+    [1, 2, 3].select! { true }.should == nil
   end
 
   it_behaves_like :keep_if, :select!
diff --git a/spec/ruby/core/array/shared/clone.rb b/spec/ruby/core/array/shared/clone.rb
index 95d0d0a3d5..1a45c2fe2c 100644
--- a/spec/ruby/core/array/shared/clone.rb
+++ b/spec/ruby/core/array/shared/clone.rb
@@ -1,14 +1,14 @@
 describe :array_clone, shared: true do
   it "returns an Array or a subclass instance" do
-    [].send(@method).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2].send(@method).should be_an_instance_of(ArraySpecs::MyArray)
+    [].send(@method).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2].send(@method).should.instance_of?(ArraySpecs::MyArray)
   end
 
   it "produces a shallow copy where the references are directly copied" do
     a = [mock('1'), mock('2')]
     b = a.send @method
-    b.first.should equal a.first
-    b.last.should equal a.last
+    b.first.should.equal? a.first
+    b.last.should.equal? a.last
   end
 
   it "creates a new array containing all elements or the original" do
@@ -17,26 +17,4 @@ describe :array_clone, shared: true do
     b.should == a
     b.__id__.should_not == a.__id__
   end
-
-  it "copies taint status from the original" do
-    a = [1, 2, 3, 4]
-    b = [1, 2, 3, 4]
-    a.taint
-    aa = a.send @method
-    bb = b.send @method
-
-    aa.tainted?.should == true
-    bb.tainted?.should == false
-  end
-
-  it "copies untrusted status from the original" do
-    a = [1, 2, 3, 4]
-    b = [1, 2, 3, 4]
-    a.untrust
-    aa = a.send @method
-    bb = b.send @method
-
-    aa.untrusted?.should == true
-    bb.untrusted?.should == false
-  end
 end
diff --git a/spec/ruby/core/array/shared/collect.rb b/spec/ruby/core/array/shared/collect.rb
deleted file mode 100644
index 80e2739893..0000000000
--- a/spec/ruby/core/array/shared/collect.rb
+++ /dev/null
@@ -1,136 +0,0 @@
-require_relative '../../enumerable/shared/enumeratorized'
-
-describe :array_collect, shared: true do
-  it "returns a copy of array with each element replaced by the value returned by block" do
-    a = ['a', 'b', 'c', 'd']
-    b = a.send(@method) { |i| i + '!' }
-    b.should == ["a!", "b!", "c!", "d!"]
-    b.should_not equal a
-  end
-
-  it "does not return subclass instance" do
-    ArraySpecs::MyArray[1, 2, 3].send(@method) { |x| x + 1 }.should be_an_instance_of(Array)
-  end
-
-  it "does not change self" do
-    a = ['a', 'b', 'c', 'd']
-    a.send(@method) { |i| i + '!' }
-    a.should == ['a', 'b', 'c', 'd']
-  end
-
-  it "returns the evaluated value of block if it broke in the block" do
-    a = ['a', 'b', 'c', 'd']
-    b = a.send(@method) {|i|
-      if i == 'c'
-        break 0
-      else
-        i + '!'
-      end
-    }
-    b.should == 0
-  end
-
-  it "returns an Enumerator when no block given" do
-    a = [1, 2, 3]
-    a.send(@method).should be_an_instance_of(Enumerator)
-  end
-
-  it "raises an ArgumentError when no block and with arguments" do
-    a = [1, 2, 3]
-    -> {
-      a.send(@method, :foo)
-    }.should raise_error(ArgumentError)
-  end
-
-  it "does not copy tainted status" do
-    a = [1, 2, 3]
-    a.taint
-    a.send(@method){|x| x}.tainted?.should be_false
-  end
-
-  it "does not copy untrusted status" do
-    a = [1, 2, 3]
-    a.untrust
-    a.send(@method){|x| x}.untrusted?.should be_false
-  end
-
-  before :all do
-    @object = [1, 2, 3, 4]
-  end
-  it_should_behave_like :enumeratorized_with_origin_size
-end
-
-describe :array_collect_b, shared: true do
-  it "replaces each element with the value returned by block" do
-    a = [7, 9, 3, 5]
-    a.send(@method) { |i| i - 1 }.should equal(a)
-    a.should == [6, 8, 2, 4]
-  end
-
-  it "returns self" do
-    a = [1, 2, 3, 4, 5]
-    b = a.send(@method) {|i| i+1 }
-    a.should equal b
-  end
-
-  it "returns the evaluated value of block but its contents is partially modified, if it broke in the block" do
-    a = ['a', 'b', 'c', 'd']
-    b = a.send(@method) {|i|
-      if i == 'c'
-        break 0
-      else
-        i + '!'
-      end
-    }
-    b.should == 0
-    a.should == ['a!', 'b!', 'c', 'd']
-  end
-
-  it "returns an Enumerator when no block given, and the enumerator can modify the original array" do
-    a = [1, 2, 3]
-    enum = a.send(@method)
-    enum.should be_an_instance_of(Enumerator)
-    enum.each{|i| "#{i}!" }
-    a.should == ["1!", "2!", "3!"]
-  end
-
-  it "keeps tainted status" do
-    a = [1, 2, 3]
-    a.taint
-    a.tainted?.should be_true
-    a.send(@method){|x| x}
-    a.tainted?.should be_true
-  end
-
-  it "keeps untrusted status" do
-    a = [1, 2, 3]
-    a.untrust
-    a.send(@method){|x| x}
-    a.untrusted?.should be_true
-  end
-
-  describe "when frozen" do
-    it "raises a #{frozen_error_class}" do
-      -> { ArraySpecs.frozen_array.send(@method) {} }.should raise_error(frozen_error_class)
-    end
-
-    it "raises a #{frozen_error_class} when empty" do
-      -> { ArraySpecs.empty_frozen_array.send(@method) {} }.should raise_error(frozen_error_class)
-    end
-
-    it "raises a #{frozen_error_class} when calling #each on the returned Enumerator" do
-      enumerator = ArraySpecs.frozen_array.send(@method)
-      -> { enumerator.each {|x| x } }.should raise_error(frozen_error_class)
-    end
-
-    it "raises a #{frozen_error_class} when calling #each on the returned Enumerator when empty" do
-      enumerator = ArraySpecs.empty_frozen_array.send(@method)
-      -> { enumerator.each {|x| x } }.should raise_error(frozen_error_class)
-    end
-  end
-
-  before :all do
-    @object = [1, 2, 3, 4]
-  end
-  it_should_behave_like :enumeratorized_with_origin_size
-end
diff --git a/spec/ruby/core/array/shared/difference.rb b/spec/ruby/core/array/shared/difference.rb
index 3e69050d82..3fe22331bd 100644
--- a/spec/ruby/core/array/shared/difference.rb
+++ b/spec/ruby/core/array/shared/difference.rb
@@ -27,13 +27,13 @@ describe :array_binary_difference, shared: true do
 
   it "raises a TypeError if the argument cannot be coerced to an Array by calling #to_ary" do
     obj = mock('not an array')
-    -> { [1, 2, 3].send(@method, obj) }.should raise_error(TypeError)
+    -> { [1, 2, 3].send(@method, obj) }.should.raise(TypeError)
   end
 
   it "does not return subclass instance for Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[]).should be_an_instance_of(Array)
-    [1, 2, 3].send(@method, ArraySpecs::MyArray[]).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[]).should.instance_of?(Array)
+    [1, 2, 3].send(@method, ArraySpecs::MyArray[]).should.instance_of?(Array)
   end
 
   it "does not call to_ary on array subclasses" do
diff --git a/spec/ruby/core/array/shared/enumeratorize.rb b/spec/ruby/core/array/shared/enumeratorize.rb
index a19a5d3b9b..5beab5c4c4 100644
--- a/spec/ruby/core/array/shared/enumeratorize.rb
+++ b/spec/ruby/core/array/shared/enumeratorize.rb
@@ -1,5 +1,5 @@
 describe :enumeratorize, shared: true do
   it "returns an Enumerator if no block given" do
-    [1,2].send(@method).should be_an_instance_of(Enumerator)
+    [1,2].send(@method).should.instance_of?(Enumerator)
   end
 end
diff --git a/spec/ruby/core/array/shared/eql.rb b/spec/ruby/core/array/shared/eql.rb
index b5d9128434..5e770bf167 100644
--- a/spec/ruby/core/array/shared/eql.rb
+++ b/spec/ruby/core/array/shared/eql.rb
@@ -1,59 +1,59 @@
 describe :array_eql, shared: true do
   it "returns true if other is the same array" do
     a = [1]
-    a.send(@method, a).should be_true
+    a.send(@method, a).should == true
   end
 
   it "returns true if corresponding elements are #eql?" do
-    [].send(@method, []).should be_true
-    [1, 2, 3, 4].send(@method, [1, 2, 3, 4]).should be_true
+    [].send(@method, []).should == true
+    [1, 2, 3, 4].send(@method, [1, 2, 3, 4]).should == true
   end
 
   it "returns false if other is shorter than self" do
-    [1, 2, 3, 4].send(@method, [1, 2, 3]).should be_false
+    [1, 2, 3, 4].send(@method, [1, 2, 3]).should == false
   end
 
   it "returns false if other is longer than self" do
-    [1, 2, 3, 4].send(@method, [1, 2, 3, 4, 5]).should be_false
+    [1, 2, 3, 4].send(@method, [1, 2, 3, 4, 5]).should == false
   end
 
   it "returns false immediately when sizes of the arrays differ" do
     obj = mock('1')
     obj.should_not_receive(@method)
 
-    []        .send(@method,    [obj]  ).should be_false
-    [obj]     .send(@method,    []     ).should be_false
+    []        .send(@method,    [obj]  ).should == false
+    [obj]     .send(@method,    []     ).should == false
   end
 
   it "handles well recursive arrays" do
     a = ArraySpecs.empty_recursive_array
-    a       .send(@method,    [a]    ).should be_true
-    a       .send(@method,    [[a]]  ).should be_true
-    [a]     .send(@method,    a      ).should be_true
-    [[a]]   .send(@method,    a      ).should be_true
+    a       .send(@method,    [a]    ).should == true
+    a       .send(@method,    [[a]]  ).should == true
+    [a]     .send(@method,    a      ).should == true
+    [[a]]   .send(@method,    a      ).should == true
     # These may be surprising, but no difference can be
     # found between these arrays, so they are ==.
     # There is no "path" that will lead to a difference
     # (contrary to other examples below)
 
     a2 = ArraySpecs.empty_recursive_array
-    a       .send(@method,    a2     ).should be_true
-    a       .send(@method,    [a2]   ).should be_true
-    a       .send(@method,    [[a2]] ).should be_true
-    [a]     .send(@method,    a2     ).should be_true
-    [[a]]   .send(@method,    a2     ).should be_true
+    a       .send(@method,    a2     ).should == true
+    a       .send(@method,    [a2]   ).should == true
+    a       .send(@method,    [[a2]] ).should == true
+    [a]     .send(@method,    a2     ).should == true
+    [[a]]   .send(@method,    a2     ).should == true
 
     back = []
     forth = [back]; back << forth;
-    back   .send(@method,  a  ).should be_true
+    back   .send(@method,  a  ).should == true
 
     x = []; x << x << x
-    x       .send(@method,    a                ).should be_false  # since x.size != a.size
-    x       .send(@method,    [a, a]           ).should be_false  # since x[0].size != [a, a][0].size
-    x       .send(@method,    [x, a]           ).should be_false  # since x[1].size != [x, a][1].size
-    [x, a]  .send(@method,    [a, x]           ).should be_false  # etc...
-    x       .send(@method,    [x, x]           ).should be_true
-    x       .send(@method,    [[x, x], [x, x]] ).should be_true
+    x       .send(@method,    a                ).should == false  # since x.size != a.size
+    x       .send(@method,    [a, a]           ).should == false  # since x[0].size != [a, a][0].size
+    x       .send(@method,    [x, a]           ).should == false  # since x[1].size != [x, a][1].size
+    [x, a]  .send(@method,    [a, x]           ).should == false  # etc...
+    x       .send(@method,    [x, x]           ).should == true
+    x       .send(@method,    [[x, x], [x, x]] ).should == true
 
     tree = [];
     branch = []; branch << tree << tree; tree << branch
@@ -62,31 +62,31 @@ describe :array_eql, shared: true do
     forest = [tree, branch, :bird, a]; forest << forest
     forest2 = [tree2, branch2, :bird, a2]; forest2 << forest2
 
-    forest .send(@method,     forest2         ).should be_true
-    forest .send(@method,     [tree2, branch, :bird, a, forest2]).should be_true
+    forest .send(@method,     forest2         ).should == true
+    forest .send(@method,     [tree2, branch, :bird, a, forest2]).should == true
 
     diffforest = [branch2, tree2, :bird, a2]; diffforest << forest2
-    forest .send(@method,     diffforest      ).should be_false # since forest[0].size == 1 != 3 == diffforest[0]
-    forest .send(@method,     [nil]           ).should be_false
-    forest .send(@method,     [forest]        ).should be_false
+    forest .send(@method,     diffforest      ).should == false # since forest[0].size == 1 != 3 == diffforest[0]
+    forest .send(@method,     [nil]           ).should == false
+    forest .send(@method,     [forest]        ).should == false
   end
 
   it "does not call #to_ary on its argument" do
     obj = mock('to_ary')
     obj.should_not_receive(:to_ary)
 
-    [1, 2, 3].send(@method, obj).should be_false
+    [1, 2, 3].send(@method, obj).should == false
   end
 
   it "does not call #to_ary on Array subclasses" do
     ary = ArraySpecs::ToAryArray[5, 6, 7]
     ary.should_not_receive(:to_ary)
-    [5, 6, 7].send(@method, ary).should be_true
+    [5, 6, 7].send(@method, ary).should == true
   end
 
   it "ignores array class differences" do
-    ArraySpecs::MyArray[1, 2, 3].send(@method, [1, 2, 3]).should be_true
-    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should be_true
-    [1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should be_true
+    ArraySpecs::MyArray[1, 2, 3].send(@method, [1, 2, 3]).should == true
+    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should == true
+    [1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should == true
   end
 end
diff --git a/spec/ruby/core/array/shared/index.rb b/spec/ruby/core/array/shared/index.rb
deleted file mode 100644
index a9896554f2..0000000000
--- a/spec/ruby/core/array/shared/index.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-describe :array_index, shared: true do
-  it "returns the index of the first element == to object" do
-    x = mock('3')
-    def x.==(obj) 3 == obj; end
-
-    [2, x, 3, 1, 3, 1].send(@method, 3).should == 1
-    [2, 3.0, 3, x, 1, 3, 1].send(@method, x).should == 1
-  end
-
-  it "returns 0 if first element == to object" do
-    [2, 1, 3, 2, 5].send(@method, 2).should == 0
-  end
-
-  it "returns size-1 if only last element == to object" do
-    [2, 1, 3, 1, 5].send(@method, 5).should == 4
-  end
-
-  it "returns nil if no element == to object" do
-    [2, 1, 1, 1, 1].send(@method, 3).should == nil
-  end
-
-  it "accepts a block instead of an argument" do
-    [4, 2, 1, 5, 1, 3].send(@method) {|x| x < 2}.should == 2
-  end
-
-  it "ignores the block if there is an argument" do
-    -> {
-      [4, 2, 1, 5, 1, 3].send(@method, 5) {|x| x < 2}.should == 3
-    }.should complain(/given block not used/)
-  end
-
-  describe "given no argument and no block" do
-    it "produces an Enumerator" do
-      [].send(@method).should be_an_instance_of(Enumerator)
-    end
-  end
-end
diff --git a/spec/ruby/core/array/shared/inspect.rb b/spec/ruby/core/array/shared/inspect.rb
deleted file mode 100644
index 434440c25b..0000000000
--- a/spec/ruby/core/array/shared/inspect.rb
+++ /dev/null
@@ -1,131 +0,0 @@
-require_relative '../fixtures/encoded_strings'
-
-describe :array_inspect, shared: true do
-  it "returns a string" do
-    [1, 2, 3].send(@method).should be_an_instance_of(String)
-  end
-
-  it "returns '[]' for an empty Array" do
-    [].send(@method).should == "[]"
-  end
-
-  it "calls inspect on its elements and joins the results with commas" do
-    items = Array.new(3) do |i|
-      obj = mock(i.to_s)
-      obj.should_receive(:inspect).and_return(i.to_s)
-      obj
-    end
-    items.send(@method).should == "[0, 1, 2]"
-  end
-
-  it "does not call #to_s on a String returned from #inspect" do
-    str = "abc"
-    str.should_not_receive(:to_s)
-
-    [str].send(@method).should == '["abc"]'
-  end
-
-  it "calls #to_s on the object returned from #inspect if the Object isn't a String" do
-    obj = mock("Array#inspect/to_s calls #to_s")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_return("abc")
-
-    [obj].send(@method).should == "[abc]"
-  end
-
-  it "does not call #to_str on the object returned from #inspect when it is not a String" do
-    obj = mock("Array#inspect/to_s does not call #to_str")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_not_receive(:to_str)
-
-    [obj].send(@method).should =~ /^\[#<MockObject:0x[0-9a-f]+>\]$/
-  end
-
-  it "does not call #to_str on the object returned from #to_s when it is not a String" do
-    obj = mock("Array#inspect/to_s does not call #to_str on #to_s result")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_return(obj)
-    obj.should_not_receive(:to_str)
-
-    [obj].send(@method).should =~ /^\[#<MockObject:0x[0-9a-f]+>\]$/
-  end
-
-  it "does not swallow exceptions raised by #to_s" do
-    obj = mock("Array#inspect/to_s does not swallow #to_s exceptions")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_raise(Exception)
-
-    -> { [obj].send(@method) }.should raise_error(Exception)
-  end
-
-  it "represents a recursive element with '[...]'" do
-    ArraySpecs.recursive_array.send(@method).should == "[1, \"two\", 3.0, [...], [...], [...], [...], [...]]"
-    ArraySpecs.head_recursive_array.send(@method).should == "[[...], [...], [...], [...], [...], 1, \"two\", 3.0]"
-    ArraySpecs.empty_recursive_array.send(@method).should == "[[...]]"
-  end
-
-  it "taints the result if the Array is non-empty and tainted" do
-    [1, 2].taint.send(@method).tainted?.should be_true
-  end
-
-  it "does not taint the result if the Array is tainted but empty" do
-    [].taint.send(@method).tainted?.should be_false
-  end
-
-  it "taints the result if an element is tainted" do
-    ["str".taint].send(@method).tainted?.should be_true
-  end
-
-  it "untrusts the result if the Array is untrusted" do
-    [1, 2].untrust.send(@method).untrusted?.should be_true
-  end
-
-  it "does not untrust the result if the Array is untrusted but empty" do
-    [].untrust.send(@method).untrusted?.should be_false
-  end
-
-  it "untrusts the result if an element is untrusted" do
-    ["str".untrust].send(@method).untrusted?.should be_true
-  end
-
-  describe "with encoding" do
-    before :each do
-      @default_external_encoding = Encoding.default_external
-    end
-
-    after :each do
-      Encoding.default_external = @default_external_encoding
-    end
-
-    it "returns a US-ASCII string for an empty Array" do
-      [].send(@method).encoding.should == Encoding::US_ASCII
-    end
-
-    it "use the default external encoding if it is ascii compatible" do
-      Encoding.default_external = Encoding.find('UTF-8')
-
-      utf8 = "utf8".encode("UTF-8")
-      jp   = "jp".encode("EUC-JP")
-      array = [jp, utf8]
-
-      array.send(@method).encoding.name.should == "UTF-8"
-    end
-
-    it "use US-ASCII encoding if the default external encoding is not ascii compatible" do
-      Encoding.default_external = Encoding.find('UTF-32')
-
-      utf8 = "utf8".encode("UTF-8")
-      jp   = "jp".encode("EUC-JP")
-      array = [jp, utf8]
-
-      array.send(@method).encoding.name.should == "US-ASCII"
-    end
-
-    it "does not raise if inspected result is not default external encoding" do
-      utf_16be = mock("utf_16be")
-      utf_16be.should_receive(:inspect).and_return(%<"utf_16be \u3042">.encode!(Encoding::UTF_16BE))
-
-      [utf_16be].send(@method).should == '["utf_16be \u3042"]'
-    end
-  end
-end
diff --git a/spec/ruby/core/array/shared/intersection.rb b/spec/ruby/core/array/shared/intersection.rb
new file mode 100644
index 0000000000..dda72e8bd7
--- /dev/null
+++ b/spec/ruby/core/array/shared/intersection.rb
@@ -0,0 +1,85 @@
+describe :array_intersection, shared: true do
+  it "creates an array with elements common to both arrays (intersection)" do
+    [].send(@method, []).should == []
+    [1, 2].send(@method, []).should == []
+    [].send(@method, [1, 2]).should == []
+    [ 1, 3, 5 ].send(@method, [ 1, 2, 3 ]).should == [1, 3]
+  end
+
+  it "creates an array with no duplicates" do
+    [ 1, 1, 3, 5 ].send(@method, [ 1, 2, 3 ]).uniq!.should == nil
+  end
+
+  it "creates an array with elements in order they are first encountered" do
+    [ 1, 2, 3, 2, 5, 6, 7, 8 ].send(@method, [ 5, 2, 3, 4 ]).should == [2, 3, 5] # array > other
+    [ 5, 2, 3, 4 ].send(@method, [ 1, 2, 3, 2, 5, 6, 7, 8 ]).should == [5, 2, 3] # array < other
+  end
+
+  it "does not modify the original Array" do
+    a = [1, 1, 3, 5]
+    a.send(@method, [1, 2, 3]).should == [1, 3]
+    a.should == [1, 1, 3, 5]
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.send(@method, empty).should == empty
+
+    ArraySpecs.recursive_array.send(@method, []).should == []
+    [].send(@method, ArraySpecs.recursive_array).should == []
+
+    ArraySpecs.recursive_array.send(@method, ArraySpecs.recursive_array).should == [1, 'two', 3.0, ArraySpecs.recursive_array]
+  end
+
+  it "tries to convert the passed argument to an Array using #to_ary" do
+    obj = mock('[1,2,3]')
+    obj.should_receive(:to_ary).and_return([1, 2, 3])
+    [1, 2].send(@method, obj).should == ([1, 2])
+  end
+
+  it "determines equivalence between elements in the sense of eql?" do
+    not_supported_on :opal do
+      [5.0, 4.0].send(@method, [5, 4]).should == []
+    end
+
+    str = "x"
+    [str].send(@method, [str.dup]).should == [str]
+
+    obj1 = mock('1')
+    obj2 = mock('2')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.should_receive(:eql?).at_least(1).and_return(true)
+    obj2.stub!(:eql?).and_return(true)
+
+    [obj1].send(@method, [obj2]).should == [obj1]
+    [obj1, obj1, obj2, obj2].send(@method, [obj2]).should == [obj1]
+
+    obj1 = mock('3')
+    obj2 = mock('4')
+    obj1.stub!(:hash).and_return(0)
+    obj2.stub!(:hash).and_return(0)
+    obj1.should_receive(:eql?).at_least(1).and_return(false)
+
+    [obj1].send(@method, [obj2]).should == []
+    [obj1, obj1, obj2, obj2].send(@method, [obj2]).should == [obj2]
+  end
+
+  it "does return subclass instances for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should.instance_of?(Array)
+    [].send(@method, ArraySpecs::MyArray[1, 2, 3]).should.instance_of?(Array)
+  end
+
+  it "does not call to_ary on array subclasses" do
+    [5, 6].send(@method, ArraySpecs::ToAryArray[1, 2, 5, 6]).should == [5, 6]
+  end
+
+  it "properly handles an identical item even when its #eql? isn't reflexive" do
+    x = mock('x')
+    x.stub!(:hash).and_return(42)
+    x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
+
+    [x].send(@method, [x]).should == [x]
+  end
+end
diff --git a/spec/ruby/core/array/shared/iterable_and_tolerating_size_increasing.rb b/spec/ruby/core/array/shared/iterable_and_tolerating_size_increasing.rb
new file mode 100644
index 0000000000..3e73bad44b
--- /dev/null
+++ b/spec/ruby/core/array/shared/iterable_and_tolerating_size_increasing.rb
@@ -0,0 +1,25 @@
+describe :array_iterable_and_tolerating_size_increasing, shared: true do
+  before do
+    @value_to_return ||= -> _ { nil }
+  end
+
+  it "tolerates increasing an array size during iteration" do
+    # The goal is to trigger potential reallocation of internal array storage, so we:
+    # - use elements of different types, starting with the less generic (Integer)
+    # - add reasonably big number of new elements (~ 100)
+    array = [1, 2, 3] # to test some methods we need several uniq elements
+    array_to_join = [:a, :b, :c] + (4..100).to_a
+
+    ScratchPad.record []
+    i = 0
+
+    array.send(@method) do |e|
+      ScratchPad << e
+      array << array_to_join[i] if i < array_to_join.size
+      i += 1
+      @value_to_return.call(e)
+    end
+
+    ScratchPad.recorded.should == [1, 2, 3] + array_to_join
+  end
+end
diff --git a/spec/ruby/core/array/shared/join.rb b/spec/ruby/core/array/shared/join.rb
index 38bdde9502..93d5329ee3 100644
--- a/spec/ruby/core/array/shared/join.rb
+++ b/spec/ruby/core/array/shared/join.rb
@@ -1,118 +1,6 @@
 require_relative '../fixtures/classes'
 require_relative '../fixtures/encoded_strings'
 
-describe :array_join_with_default_separator, shared: true do
-  before :each do
-    @separator = $,
-  end
-
-  after :each do
-    $, = @separator
-  end
-
-  it "returns an empty string if the Array is empty" do
-    [].send(@method).should == ''
-  end
-
-  it "returns a US-ASCII string for an empty Array" do
-    [].send(@method).encoding.should == Encoding::US_ASCII
-  end
-
-  it "returns a string formed by concatenating each String element separated by $," do
-    suppress_warning {
-      $, = " | "
-      ["1", "2", "3"].send(@method).should == "1 | 2 | 3"
-    }
-  end
-
-  it "attempts coercion via #to_str first" do
-    obj = mock('foo')
-    obj.should_receive(:to_str).any_number_of_times.and_return("foo")
-    [obj].send(@method).should == "foo"
-  end
-
-  it "attempts coercion via #to_ary second" do
-    obj = mock('foo')
-    obj.should_receive(:to_str).any_number_of_times.and_return(nil)
-    obj.should_receive(:to_ary).any_number_of_times.and_return(["foo"])
-    [obj].send(@method).should == "foo"
-  end
-
-  it "attempts coercion via #to_s third" do
-    obj = mock('foo')
-    obj.should_receive(:to_str).any_number_of_times.and_return(nil)
-    obj.should_receive(:to_ary).any_number_of_times.and_return(nil)
-    obj.should_receive(:to_s).any_number_of_times.and_return("foo")
-    [obj].send(@method).should == "foo"
-  end
-
-  it "raises a NoMethodError if an element does not respond to #to_str, #to_ary, or #to_s" do
-    obj = mock('o')
-    class << obj; undef :to_s; end
-    -> { [1, obj].send(@method) }.should raise_error(NoMethodError)
-  end
-
-  it "raises an ArgumentError when the Array is recursive" do
-    -> { ArraySpecs.recursive_array.send(@method) }.should raise_error(ArgumentError)
-    -> { ArraySpecs.head_recursive_array.send(@method) }.should raise_error(ArgumentError)
-    -> { ArraySpecs.empty_recursive_array.send(@method) }.should raise_error(ArgumentError)
-  end
-
-  it "taints the result if the Array is tainted and non-empty" do
-    [1, 2].taint.send(@method).tainted?.should be_true
-  end
-
-  it "does not taint the result if the Array is tainted but empty" do
-    [].taint.send(@method).tainted?.should be_false
-  end
-
-  it "taints the result if the result of coercing an element is tainted" do
-    s = mock("taint")
-    s.should_receive(:to_s).and_return("str".taint)
-    [s].send(@method).tainted?.should be_true
-  end
-
-  it "untrusts the result if the Array is untrusted and non-empty" do
-    [1, 2].untrust.send(@method).untrusted?.should be_true
-  end
-
-  it "does not untrust the result if the Array is untrusted but empty" do
-    [].untrust.send(@method).untrusted?.should be_false
-  end
-
-  it "untrusts the result if the result of coercing an element is untrusted" do
-    s = mock("untrust")
-    s.should_receive(:to_s).and_return("str".untrust)
-    [s].send(@method).untrusted?.should be_true
-  end
-
-  it "uses the first encoding when other strings are compatible" do
-    ary1 = ArraySpecs.array_with_7bit_utf8_and_usascii_strings
-    ary2 = ArraySpecs.array_with_usascii_and_7bit_utf8_strings
-    ary3 = ArraySpecs.array_with_utf8_and_7bit_binary_strings
-    ary4 = ArraySpecs.array_with_usascii_and_7bit_binary_strings
-
-    ary1.send(@method).encoding.should == Encoding::UTF_8
-    ary2.send(@method).encoding.should == Encoding::US_ASCII
-    ary3.send(@method).encoding.should == Encoding::UTF_8
-    ary4.send(@method).encoding.should == Encoding::US_ASCII
-  end
-
-  it "uses the widest common encoding when other strings are incompatible" do
-    ary1 = ArraySpecs.array_with_utf8_and_usascii_strings
-    ary2 = ArraySpecs.array_with_usascii_and_utf8_strings
-
-    ary1.send(@method).encoding.should == Encoding::UTF_8
-    ary2.send(@method).encoding.should == Encoding::UTF_8
-  end
-
-  it "fails for arrays with incompatibly-encoded strings" do
-    ary_utf8_bad_binary = ArraySpecs.array_with_utf8_and_binary_strings
-
-    -> { ary_utf8_bad_binary.send(@method) }.should raise_error(EncodingError)
-  end
-end
-
 describe :array_join_with_string_separator, shared: true do
   it "returns a string formed by concatenating each element.to_str separated by separator" do
     obj = mock('foo')
@@ -124,40 +12,4 @@ describe :array_join_with_string_separator, shared: true do
     [1, [2, [3, 4], 5], 6].send(@method, ":").should == "1:2:3:4:5:6"
     [1, [2, ArraySpecs::MyArray[3, 4], 5], 6].send(@method, ":").should == "1:2:3:4:5:6"
   end
-
-  describe "with a tainted separator" do
-    before :each do
-      @sep = ":".taint
-    end
-
-    it "does not taint the result if the array is empty" do
-      [].send(@method, @sep).tainted?.should be_false
-    end
-
-    it "does not taint the result if the array has only one element" do
-      [1].send(@method, @sep).tainted?.should be_false
-    end
-
-    it "taints the result if the array has two or more elements" do
-      [1, 2].send(@method, @sep).tainted?.should be_true
-    end
-  end
-
-  describe "with an untrusted separator" do
-    before :each do
-      @sep = ":".untrust
-    end
-
-    it "does not untrust the result if the array is empty" do
-      [].send(@method, @sep).untrusted?.should be_false
-    end
-
-    it "does not untrust the result if the array has only one element" do
-      [1].send(@method, @sep).untrusted?.should be_false
-    end
-
-    it "untrusts the result if the array has two or more elements" do
-      [1, 2].send(@method, @sep).untrusted?.should be_true
-    end
-  end
 end
diff --git a/spec/ruby/core/array/shared/keep_if.rb b/spec/ruby/core/array/shared/keep_if.rb
index 2f1299c2b3..44625eebd1 100644
--- a/spec/ruby/core/array/shared/keep_if.rb
+++ b/spec/ruby/core/array/shared/keep_if.rb
@@ -1,14 +1,15 @@
 require_relative '../../enumerable/shared/enumeratorized'
+require_relative '../shared/iterable_and_tolerating_size_increasing'
 
 describe :keep_if, shared: true do
   it "deletes elements for which the block returns a false value" do
     array = [1, 2, 3, 4, 5]
-    array.send(@method) {|item| item > 3 }.should equal(array)
+    array.send(@method) {|item| item > 3 }.should.equal?(array)
     array.should == [4, 5]
   end
 
   it "returns an enumerator if no block is given" do
-    [1, 2, 3].send(@method).should be_an_instance_of(Enumerator)
+    [1, 2, 3].send(@method).should.instance_of?(Enumerator)
   end
 
   it "updates the receiver after all blocks" do
@@ -32,29 +33,63 @@ describe :keep_if, shared: true do
     end
 
     it "returns an Enumerator if no block is given" do
-      @frozen.send(@method).should be_an_instance_of(Enumerator)
+      @frozen.send(@method).should.instance_of?(Enumerator)
     end
 
     describe "with truthy block" do
       it "keeps elements after any exception" do
-        -> { @frozen.send(@method) { true } }.should raise_error(Exception)
+        -> { @frozen.send(@method) { true } }.should.raise(Exception)
         @frozen.should == @origin
       end
 
-      it "raises a #{frozen_error_class}" do
-        -> { @frozen.send(@method) { true } }.should raise_error(frozen_error_class)
+      it "raises a FrozenError" do
+        -> { @frozen.send(@method) { true } }.should.raise(FrozenError)
       end
     end
 
     describe "with falsy block" do
       it "keeps elements after any exception" do
-        -> { @frozen.send(@method) { false } }.should raise_error(Exception)
+        -> { @frozen.send(@method) { false } }.should.raise(Exception)
         @frozen.should == @origin
       end
 
-      it "raises a #{frozen_error_class}" do
-        -> { @frozen.send(@method) { false } }.should raise_error(frozen_error_class)
+      it "raises a FrozenError" do
+        -> { @frozen.send(@method) { false } }.should.raise(FrozenError)
       end
     end
+
+    it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+      enum = @frozen.send(@method)
+      -> { enum.each {} }.should.raise(FrozenError)
+    end
+  end
+
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.send(@method) { raise StandardError, 'Oops' }
+    rescue
+    end
+
+    a.should == [1, 2, 3]
   end
+
+  it "only changes elements before error is raised, keeping the element which raised an error." do
+    a = [1, 2, 3, 4]
+    begin
+      a.send(@method) do |e|
+        case e
+        when 2 then false
+        when 3 then raise StandardError, 'Oops'
+        else true
+        end
+      end
+    rescue StandardError
+    end
+
+    a.should == [1, 3, 4]
+  end
+
+  @value_to_return = -> _ { true }
+  it_should_behave_like :array_iterable_and_tolerating_size_increasing
 end
diff --git a/spec/ruby/core/array/shared/length.rb b/spec/ruby/core/array/shared/length.rb
deleted file mode 100644
index f84966d0ba..0000000000
--- a/spec/ruby/core/array/shared/length.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-describe :array_length, shared: true do
-  it "returns the number of elements" do
-    [].send(@method).should == 0
-    [1, 2, 3].send(@method).should == 3
-  end
-
-  it "properly handles recursive arrays" do
-    ArraySpecs.empty_recursive_array.send(@method).should == 1
-    ArraySpecs.recursive_array.send(@method).should == 8
-  end
-end
diff --git a/spec/ruby/core/array/shared/push.rb b/spec/ruby/core/array/shared/push.rb
deleted file mode 100644
index df307073cd..0000000000
--- a/spec/ruby/core/array/shared/push.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-describe :array_push, shared: true do
-  it "appends the arguments to the array" do
-    a = [ "a", "b", "c" ]
-    a.send(@method, "d", "e", "f").should equal(a)
-    a.send(@method).should == ["a", "b", "c", "d", "e", "f"]
-    a.send(@method, 5)
-    a.should == ["a", "b", "c", "d", "e", "f", 5]
-
-    a = [0, 1]
-    a.send(@method, 2)
-    a.should == [0, 1, 2]
-  end
-
-  it "isn't confused by previous shift" do
-    a = [ "a", "b", "c" ]
-    a.shift
-    a.send(@method, "foo")
-    a.should == ["b", "c", "foo"]
-  end
-
-  it "properly handles recursive arrays" do
-    empty = ArraySpecs.empty_recursive_array
-    empty.send(@method, :last).should == [empty, :last]
-
-    array = ArraySpecs.recursive_array
-    array.send(@method, :last).should == [1, 'two', 3.0, array, array, array, array, array, :last]
-  end
-
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.send(@method, 1) }.should raise_error(frozen_error_class)
-    -> { ArraySpecs.frozen_array.send(@method) }.should raise_error(frozen_error_class)
-  end
-end
diff --git a/spec/ruby/core/array/shared/replace.rb b/spec/ruby/core/array/shared/replace.rb
deleted file mode 100644
index b3474fad09..0000000000
--- a/spec/ruby/core/array/shared/replace.rb
+++ /dev/null
@@ -1,60 +0,0 @@
-describe :array_replace, shared: true do
-  it "replaces the elements with elements from other array" do
-    a = [1, 2, 3, 4, 5]
-    b = ['a', 'b', 'c']
-    a.send(@method, b).should equal(a)
-    a.should == b
-    a.should_not equal(b)
-
-    a.send(@method, [4] * 10)
-    a.should == [4] * 10
-
-    a.send(@method, [])
-    a.should == []
-  end
-
-  it "properly handles recursive arrays" do
-    orig = [1, 2, 3]
-    empty = ArraySpecs.empty_recursive_array
-    orig.send(@method, empty)
-    orig.should == empty
-
-    array = ArraySpecs.recursive_array
-    orig.send(@method, array)
-    orig.should == array
-  end
-
-  it "returns self" do
-    ary = [1, 2, 3]
-    other = [:a, :b, :c]
-    ary.send(@method, other).should equal(ary)
-  end
-
-  it "does not make self dependent to the original array" do
-    ary = [1, 2, 3]
-    other = [:a, :b, :c]
-    ary.send(@method, other)
-    ary.should == [:a, :b, :c]
-    ary << :d
-    ary.should == [:a, :b, :c, :d]
-    other.should == [:a, :b, :c]
-  end
-
-  it "tries to convert the passed argument to an Array using #to_ary" do
-    obj = mock('to_ary')
-    obj.stub!(:to_ary).and_return([1, 2, 3])
-    [].send(@method, obj).should == [1, 2, 3]
-  end
-
-  it "does not call #to_ary on Array subclasses" do
-    obj = ArraySpecs::ToAryArray[5, 6, 7]
-    obj.should_not_receive(:to_ary)
-    [].send(@method, ArraySpecs::ToAryArray[5, 6, 7]).should == [5, 6, 7]
-  end
-
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> {
-      ArraySpecs.frozen_array.send(@method, ArraySpecs.frozen_array)
-    }.should raise_error(frozen_error_class)
-  end
-end
diff --git a/spec/ruby/core/array/shared/select.rb b/spec/ruby/core/array/shared/select.rb
deleted file mode 100644
index 09101e8ab5..0000000000
--- a/spec/ruby/core/array/shared/select.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../fixtures/classes'
-require_relative '../shared/enumeratorize'
-require_relative '../shared/keep_if'
-require_relative '../../enumerable/shared/enumeratorized'
-
-describe :array_select, shared: true do
-  it_should_behave_like :enumeratorize
-
-  before :each do
-    @object = [1,2,3]
-  end
-  it_should_behave_like :enumeratorized_with_origin_size
-
-  it "returns a new array of elements for which block is true" do
-    [1, 3, 4, 5, 6, 9].send(@method) { |i| i % ((i + 1) / 2) == 0}.should == [1, 4, 6]
-  end
-
-  it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].send(@method) { true }.should be_an_instance_of(Array)
-  end
-
-  it "properly handles recursive arrays" do
-    empty = ArraySpecs.empty_recursive_array
-    empty.send(@method) { true }.should == empty
-    empty.send(@method) { false }.should == []
-
-    array = ArraySpecs.recursive_array
-    array.send(@method) { true }.should == [1, 'two', 3.0, array, array, array, array, array]
-    array.send(@method) { false }.should == []
-  end
-end
diff --git a/spec/ruby/core/array/shared/slice.rb b/spec/ruby/core/array/shared/slice.rb
deleted file mode 100644
index 73456eb297..0000000000
--- a/spec/ruby/core/array/shared/slice.rb
+++ /dev/null
@@ -1,459 +0,0 @@
-describe :array_slice, shared: true do
-  it "returns the element at index with [index]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 1).should == "b"
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, 0).should == 1
-    a.send(@method, 1).should == 2
-    a.send(@method, 2).should == 3
-    a.send(@method, 3).should == 4
-    a.send(@method, 4).should == nil
-    a.send(@method, 10).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns the element at index from the end of the array with [-index]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, -2).should == "d"
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, -1).should == 4
-    a.send(@method, -2).should == 3
-    a.send(@method, -3).should == 2
-    a.send(@method, -4).should == 1
-    a.send(@method, -5).should == nil
-    a.send(@method, -10).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns count elements starting from index with [index, count]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 2, 3).should == ["c", "d", "e"]
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, 0, 0).should == []
-    a.send(@method, 0, 1).should == [1]
-    a.send(@method, 0, 2).should == [1, 2]
-    a.send(@method, 0, 4).should == [1, 2, 3, 4]
-    a.send(@method, 0, 6).should == [1, 2, 3, 4]
-    a.send(@method, 0, -1).should == nil
-    a.send(@method, 0, -2).should == nil
-    a.send(@method, 0, -4).should == nil
-
-    a.send(@method, 2, 0).should == []
-    a.send(@method, 2, 1).should == [3]
-    a.send(@method, 2, 2).should == [3, 4]
-    a.send(@method, 2, 4).should == [3, 4]
-    a.send(@method, 2, -1).should == nil
-
-    a.send(@method, 4, 0).should == []
-    a.send(@method, 4, 2).should == []
-    a.send(@method, 4, -1).should == nil
-
-    a.send(@method, 5, 0).should == nil
-    a.send(@method, 5, 2).should == nil
-    a.send(@method, 5, -1).should == nil
-
-    a.send(@method, 6, 0).should == nil
-    a.send(@method, 6, 2).should == nil
-    a.send(@method, 6, -1).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns count elements starting at index from the end of array with [-index, count]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, -2, 2).should == ["d", "e"]
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, -1, 0).should == []
-    a.send(@method, -1, 1).should == [4]
-    a.send(@method, -1, 2).should == [4]
-    a.send(@method, -1, -1).should == nil
-
-    a.send(@method, -2, 0).should == []
-    a.send(@method, -2, 1).should == [3]
-    a.send(@method, -2, 2).should == [3, 4]
-    a.send(@method, -2, 4).should == [3, 4]
-    a.send(@method, -2, -1).should == nil
-
-    a.send(@method, -4, 0).should == []
-    a.send(@method, -4, 1).should == [1]
-    a.send(@method, -4, 2).should == [1, 2]
-    a.send(@method, -4, 4).should == [1, 2, 3, 4]
-    a.send(@method, -4, 6).should == [1, 2, 3, 4]
-    a.send(@method, -4, -1).should == nil
-
-    a.send(@method, -5, 0).should == nil
-    a.send(@method, -5, 1).should == nil
-    a.send(@method, -5, 10).should == nil
-    a.send(@method, -5, -1).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns the first count elements with [0, count]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 0, 3).should == ["a", "b", "c"]
-  end
-
-  it "returns the subarray which is independent to self with [index,count]" do
-    a = [1, 2, 3]
-    sub = a.send(@method, 1,2)
-    sub.replace([:a, :b])
-    a.should == [1, 2, 3]
-  end
-
-  it "tries to convert the passed argument to an Integer using #to_int" do
-    obj = mock('to_int')
-    obj.stub!(:to_int).and_return(2)
-
-    a = [1, 2, 3, 4]
-    a.send(@method, obj).should == 3
-    a.send(@method, obj, 1).should == [3]
-    a.send(@method, obj, obj).should == [3, 4]
-    a.send(@method, 0, obj).should == [1, 2]
-  end
-
-  it "returns the elements specified by Range indexes with [m..n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 1..3).should == ["b", "c", "d"]
-    [ "a", "b", "c", "d", "e" ].send(@method, 4..-1).should == ['e']
-    [ "a", "b", "c", "d", "e" ].send(@method, 3..3).should == ['d']
-    [ "a", "b", "c", "d", "e" ].send(@method, 3..-2).should == ['d']
-    ['a'].send(@method, 0..-1).should == ['a']
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, 0..-10).should == []
-    a.send(@method, 0..0).should == [1]
-    a.send(@method, 0..1).should == [1, 2]
-    a.send(@method, 0..2).should == [1, 2, 3]
-    a.send(@method, 0..3).should == [1, 2, 3, 4]
-    a.send(@method, 0..4).should == [1, 2, 3, 4]
-    a.send(@method, 0..10).should == [1, 2, 3, 4]
-
-    a.send(@method, 2..-10).should == []
-    a.send(@method, 2..0).should == []
-    a.send(@method, 2..2).should == [3]
-    a.send(@method, 2..3).should == [3, 4]
-    a.send(@method, 2..4).should == [3, 4]
-
-    a.send(@method, 3..0).should == []
-    a.send(@method, 3..3).should == [4]
-    a.send(@method, 3..4).should == [4]
-
-    a.send(@method, 4..0).should == []
-    a.send(@method, 4..4).should == []
-    a.send(@method, 4..5).should == []
-
-    a.send(@method, 5..0).should == nil
-    a.send(@method, 5..5).should == nil
-    a.send(@method, 5..6).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns elements specified by Range indexes except the element at index n with [m...n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 1...3).should == ["b", "c"]
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, 0...-10).should == []
-    a.send(@method, 0...0).should == []
-    a.send(@method, 0...1).should == [1]
-    a.send(@method, 0...2).should == [1, 2]
-    a.send(@method, 0...3).should == [1, 2, 3]
-    a.send(@method, 0...4).should == [1, 2, 3, 4]
-    a.send(@method, 0...10).should == [1, 2, 3, 4]
-
-    a.send(@method, 2...-10).should == []
-    a.send(@method, 2...0).should == []
-    a.send(@method, 2...2).should == []
-    a.send(@method, 2...3).should == [3]
-    a.send(@method, 2...4).should == [3, 4]
-
-    a.send(@method, 3...0).should == []
-    a.send(@method, 3...3).should == []
-    a.send(@method, 3...4).should == [4]
-
-    a.send(@method, 4...0).should == []
-    a.send(@method, 4...4).should == []
-    a.send(@method, 4...5).should == []
-
-    a.send(@method, 5...0).should == nil
-    a.send(@method, 5...5).should == nil
-    a.send(@method, 5...6).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns elements that exist if range start is in the array but range end is not with [m..n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 4..7).should == ["e"]
-  end
-
-  it "accepts Range instances having a negative m and both signs for n with [m..n] and [m...n]" do
-    a = [1, 2, 3, 4]
-
-    a.send(@method, -1..-1).should == [4]
-    a.send(@method, -1...-1).should == []
-    a.send(@method, -1..3).should == [4]
-    a.send(@method, -1...3).should == []
-    a.send(@method, -1..4).should == [4]
-    a.send(@method, -1...4).should == [4]
-    a.send(@method, -1..10).should == [4]
-    a.send(@method, -1...10).should == [4]
-    a.send(@method, -1..0).should == []
-    a.send(@method, -1..-4).should == []
-    a.send(@method, -1...-4).should == []
-    a.send(@method, -1..-6).should == []
-    a.send(@method, -1...-6).should == []
-
-    a.send(@method, -2..-2).should == [3]
-    a.send(@method, -2...-2).should == []
-    a.send(@method, -2..-1).should == [3, 4]
-    a.send(@method, -2...-1).should == [3]
-    a.send(@method, -2..10).should == [3, 4]
-    a.send(@method, -2...10).should == [3, 4]
-
-    a.send(@method, -4..-4).should == [1]
-    a.send(@method, -4..-2).should == [1, 2, 3]
-    a.send(@method, -4...-2).should == [1, 2]
-    a.send(@method, -4..-1).should == [1, 2, 3, 4]
-    a.send(@method, -4...-1).should == [1, 2, 3]
-    a.send(@method, -4..3).should == [1, 2, 3, 4]
-    a.send(@method, -4...3).should == [1, 2, 3]
-    a.send(@method, -4..4).should == [1, 2, 3, 4]
-    a.send(@method, -4...4).should == [1, 2, 3, 4]
-    a.send(@method, -4...4).should == [1, 2, 3, 4]
-    a.send(@method, -4..0).should == [1]
-    a.send(@method, -4...0).should == []
-    a.send(@method, -4..1).should == [1, 2]
-    a.send(@method, -4...1).should == [1]
-
-    a.send(@method, -5..-5).should == nil
-    a.send(@method, -5...-5).should == nil
-    a.send(@method, -5..-4).should == nil
-    a.send(@method, -5..-1).should == nil
-    a.send(@method, -5..10).should == nil
-
-    a.should == [1, 2, 3, 4]
-  end
-
-  it "returns the subarray which is independent to self with [m..n]" do
-    a = [1, 2, 3]
-    sub = a.send(@method, 1..2)
-    sub.replace([:a, :b])
-    a.should == [1, 2, 3]
-  end
-
-  it "tries to convert Range elements to Integers using #to_int with [m..n] and [m...n]" do
-    from = mock('from')
-    to = mock('to')
-
-    # So we can construct a range out of them...
-    def from.<=>(o) 0 end
-    def to.<=>(o) 0 end
-
-    def from.to_int() 1 end
-    def to.to_int() -2 end
-
-    a = [1, 2, 3, 4]
-
-    a.send(@method, from..to).should == [2, 3]
-    a.send(@method, from...to).should == [2]
-    a.send(@method, 1..0).should == []
-    a.send(@method, 1...0).should == []
-
-    -> { a.send(@method, "a" .. "b") }.should raise_error(TypeError)
-    -> { a.send(@method, "a" ... "b") }.should raise_error(TypeError)
-    -> { a.send(@method, from .. "b") }.should raise_error(TypeError)
-    -> { a.send(@method, from ... "b") }.should raise_error(TypeError)
-  end
-
-  it "returns the same elements as [m..n] and [m...n] with Range subclasses" do
-    a = [1, 2, 3, 4]
-    range_incl = ArraySpecs::MyRange.new(1, 2)
-    range_excl = ArraySpecs::MyRange.new(-3, -1, true)
-
-    a.send(@method, range_incl).should == [2, 3]
-    a.send(@method, range_excl).should == [2, 3]
-  end
-
-  it "returns nil for a requested index not in the array with [index]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 5).should == nil
-  end
-
-  it "returns [] if the index is valid but length is zero with [index, length]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 0, 0).should == []
-    [ "a", "b", "c", "d", "e" ].send(@method, 2, 0).should == []
-  end
-
-  it "returns nil if length is zero but index is invalid with [index, length]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 100, 0).should == nil
-    [ "a", "b", "c", "d", "e" ].send(@method, -50, 0).should == nil
-  end
-
-  # This is by design. It is in the official documentation.
-  it "returns [] if index == array.size with [index, length]" do
-    %w|a b c d e|.send(@method, 5, 2).should == []
-  end
-
-  it "returns nil if index > array.size with [index, length]" do
-    %w|a b c d e|.send(@method, 6, 2).should == nil
-  end
-
-  it "returns nil if length is negative with [index, length]" do
-    %w|a b c d e|.send(@method, 3, -1).should == nil
-    %w|a b c d e|.send(@method, 2, -2).should == nil
-    %w|a b c d e|.send(@method, 1, -100).should == nil
-  end
-
-  it "returns nil if no requested index is in the array with [m..n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, 6..10).should == nil
-  end
-
-  it "returns nil if range start is not in the array with [m..n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, -10..2).should == nil
-    [ "a", "b", "c", "d", "e" ].send(@method, 10..12).should == nil
-  end
-
-  it "returns an empty array when m == n with [m...n]" do
-    [1, 2, 3, 4, 5].send(@method, 1...1).should == []
-  end
-
-  it "returns an empty array with [0...0]" do
-    [1, 2, 3, 4, 5].send(@method, 0...0).should == []
-  end
-
-  it "returns a subarray where m, n negatives and m < n with [m..n]" do
-    [ "a", "b", "c", "d", "e" ].send(@method, -3..-2).should == ["c", "d"]
-  end
-
-  it "returns an array containing the first element with [0..0]" do
-    [1, 2, 3, 4, 5].send(@method, 0..0).should == [1]
-  end
-
-  it "returns the entire array with [0..-1]" do
-    [1, 2, 3, 4, 5].send(@method, 0..-1).should == [1, 2, 3, 4, 5]
-  end
-
-  it "returns all but the last element with [0...-1]" do
-    [1, 2, 3, 4, 5].send(@method, 0...-1).should == [1, 2, 3, 4]
-  end
-
-  it "returns [3] for [2..-1] out of [1, 2, 3]" do
-    [1,2,3].send(@method, 2..-1).should == [3]
-  end
-
-  it "returns an empty array when m > n and m, n are positive with [m..n]" do
-    [1, 2, 3, 4, 5].send(@method, 3..2).should == []
-  end
-
-  it "returns an empty array when m > n and m, n are negative with [m..n]" do
-    [1, 2, 3, 4, 5].send(@method, -2..-3).should == []
-  end
-
-  it "does not expand array when the indices are outside of the array bounds" do
-    a = [1, 2]
-    a.send(@method, 4).should == nil
-    a.should == [1, 2]
-    a.send(@method, 4, 0).should == nil
-    a.should == [1, 2]
-    a.send(@method, 6, 1).should == nil
-    a.should == [1, 2]
-    a.send(@method, 8...8).should == nil
-    a.should == [1, 2]
-    a.send(@method, 10..10).should == nil
-    a.should == [1, 2]
-  end
-
-  describe "with a subclass of Array" do
-    before :each do
-      ScratchPad.clear
-
-      @array = ArraySpecs::MyArray[1, 2, 3, 4, 5]
-    end
-
-    it "returns a subclass instance with [n, m]" do
-      @array.send(@method, 0, 2).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns a subclass instance with [-n, m]" do
-      @array.send(@method, -3, 2).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns a subclass instance with [n..m]" do
-      @array.send(@method, 1..3).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns a subclass instance with [n...m]" do
-      @array.send(@method, 1...3).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns a subclass instance with [-n..-m]" do
-      @array.send(@method, -3..-1).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns a subclass instance with [-n...-m]" do
-      @array.send(@method, -3...-1).should be_an_instance_of(ArraySpecs::MyArray)
-    end
-
-    it "returns an empty array when m == n with [m...n]" do
-      @array.send(@method, 1...1).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "returns an empty array with [0...0]" do
-      @array.send(@method, 0...0).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "returns an empty array when m > n and m, n are positive with [m..n]" do
-      @array.send(@method, 3..2).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "returns an empty array when m > n and m, n are negative with [m..n]" do
-      @array.send(@method, -2..-3).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "returns [] if index == array.size with [index, length]" do
-      @array.send(@method, 5, 2).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "returns [] if the index is valid but length is zero with [index, length]" do
-      @array.send(@method, 0, 0).should == []
-      @array.send(@method, 2, 0).should == []
-      ScratchPad.recorded.should be_nil
-    end
-
-    it "does not call #initialize on the subclass instance" do
-      @array.send(@method, 0, 3).should == [1, 2, 3]
-      ScratchPad.recorded.should be_nil
-    end
-  end
-
-  it "raises a RangeError when the start index is out of range of Fixnum" do
-    array = [1, 2, 3, 4, 5, 6]
-    obj = mock('large value')
-    obj.should_receive(:to_int).and_return(0x8000_0000_0000_0000_0000)
-    -> { array.send(@method, obj) }.should raise_error(RangeError)
-
-    obj = 8e19
-    -> { array.send(@method, obj) }.should raise_error(RangeError)
-  end
-
-  it "raises a RangeError when the length is out of range of Fixnum" do
-    array = [1, 2, 3, 4, 5, 6]
-    obj = mock('large value')
-    obj.should_receive(:to_int).and_return(0x8000_0000_0000_0000_0000)
-    -> { array.send(@method, 1, obj) }.should raise_error(RangeError)
-
-    obj = 8e19
-    -> { array.send(@method, 1, obj) }.should raise_error(RangeError)
-  end
-end
diff --git a/spec/ruby/core/array/shared/union.rb b/spec/ruby/core/array/shared/union.rb
index 12a98cc9fe..0b225b9a31 100644
--- a/spec/ruby/core/array/shared/union.rb
+++ b/spec/ruby/core/array/shared/union.rb
@@ -31,7 +31,7 @@ describe :array_binary_union, shared: true do
     [0].send(@method, obj).should == ([0] | [1, 2, 3])
   end
 
-  # MRI follows hashing semantics here, so doesn't actually call eql?/hash for Fixnum/Symbol
+  # MRI follows hashing semantics here, so doesn't actually call eql?/hash for Integer/Symbol
   it "acts as if using an intermediate hash to collect values" do
     not_supported_on :opal do
       [5.0, 4.0].send(@method, [5, 4]).should == [5.0, 4.0, 5, 4]
@@ -60,9 +60,9 @@ describe :array_binary_union, shared: true do
   end
 
   it "does not return subclass instances for Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should be_an_instance_of(Array)
-    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
-    [].send(@method, ArraySpecs::MyArray[1, 2, 3]).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, []).should.instance_of?(Array)
+    ArraySpecs::MyArray[1, 2, 3].send(@method, ArraySpecs::MyArray[1, 2, 3]).should.instance_of?(Array)
+    [].send(@method, ArraySpecs::MyArray[1, 2, 3]).should.instance_of?(Array)
   end
 
   it "does not call to_ary on array subclasses" do
diff --git a/spec/ruby/core/array/shared/unshift.rb b/spec/ruby/core/array/shared/unshift.rb
deleted file mode 100644
index be62084e95..0000000000
--- a/spec/ruby/core/array/shared/unshift.rb
+++ /dev/null
@@ -1,46 +0,0 @@
-describe :array_unshift, shared: true do
-  it "prepends object to the original array" do
-    a = [1, 2, 3]
-    a.send(@method, "a").should equal(a)
-    a.should == ['a', 1, 2, 3]
-    a.send(@method).should equal(a)
-    a.should == ['a', 1, 2, 3]
-    a.send(@method, 5, 4, 3)
-    a.should == [5, 4, 3, 'a', 1, 2, 3]
-
-    # shift all but one element
-    a = [1, 2]
-    a.shift
-    a.send(@method, 3, 4)
-    a.should == [3, 4, 2]
-
-    # now shift all elements
-    a.shift
-    a.shift
-    a.shift
-    a.send(@method, 3, 4)
-    a.should == [3, 4]
-  end
-
-  it "quietly ignores unshifting nothing" do
-    [].send(@method).should == []
-  end
-
-  it "properly handles recursive arrays" do
-    empty = ArraySpecs.empty_recursive_array
-    empty.send(@method, :new).should == [:new, empty]
-
-    array = ArraySpecs.recursive_array
-    array.send(@method, :new)
-    array[0..5].should == [:new, 1, 'two', 3.0, array, array]
-  end
-
-  it "raises a #{frozen_error_class} on a frozen array when the array is modified" do
-    -> { ArraySpecs.frozen_array.send(@method, 1) }.should raise_error(frozen_error_class)
-  end
-
-  # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen array when the array would not be modified" do
-    -> { ArraySpecs.frozen_array.send(@method) }.should raise_error(frozen_error_class)
-  end
-end
diff --git a/spec/ruby/core/array/shift_spec.rb b/spec/ruby/core/array/shift_spec.rb
index ef3c9fe1cd..09dfa79c45 100644
--- a/spec/ruby/core/array/shift_spec.rb
+++ b/spec/ruby/core/array/shift_spec.rb
@@ -30,11 +30,11 @@ describe "Array#shift" do
     array[0..2].should == ['two', 3.0, array]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.shift }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.shift }.should.raise(FrozenError)
   end
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.shift }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.shift }.should.raise(FrozenError)
   end
 
   describe "passed a number n as an argument" do
@@ -72,7 +72,7 @@ describe "Array#shift" do
       popped2.should == []
       a.should == []
 
-      popped1.should_not equal(popped2)
+      popped1.should_not.equal?(popped2)
     end
 
     it "returns whole elements if n exceeds size of the array" do
@@ -83,14 +83,14 @@ describe "Array#shift" do
 
     it "does not return self even when it returns whole elements" do
       a = [1, 2, 3, 4, 5]
-      a.shift(5).should_not equal(a)
+      a.shift(5).should_not.equal?(a)
 
       a = [1, 2, 3, 4, 5]
-      a.shift(6).should_not equal(a)
+      a.shift(6).should_not.equal?(a)
     end
 
     it "raises an ArgumentError if n is negative" do
-      ->{ [1, 2, 3].shift(-1) }.should raise_error(ArgumentError)
+      ->{ [1, 2, 3].shift(-1) }.should.raise(ArgumentError)
     end
 
     it "tries to convert n to an Integer using #to_int" do
@@ -105,30 +105,16 @@ describe "Array#shift" do
     end
 
     it "raises a TypeError when the passed n cannot be coerced to Integer" do
-      ->{ [1, 2].shift("cat") }.should raise_error(TypeError)
-      ->{ [1, 2].shift(nil) }.should raise_error(TypeError)
+      ->{ [1, 2].shift("cat") }.should.raise(TypeError)
+      ->{ [1, 2].shift(nil) }.should.raise(TypeError)
     end
 
     it "raises an ArgumentError if more arguments are passed" do
-      ->{ [1, 2].shift(1, 2) }.should raise_error(ArgumentError)
+      ->{ [1, 2].shift(1, 2) }.should.raise(ArgumentError)
     end
 
     it "does not return subclass instances with Array subclass" do
-      ArraySpecs::MyArray[1, 2, 3].shift(2).should be_an_instance_of(Array)
-    end
-
-    it "returns an untainted array even if the array is tainted" do
-      ary = [1, 2].taint
-      ary.shift(2).tainted?.should be_false
-      ary.shift(0).tainted?.should be_false
-    end
-
-    it "keeps taint status" do
-      a = [1, 2].taint
-      a.shift(2)
-      a.tainted?.should be_true
-      a.shift(2)
-      a.tainted?.should be_true
+      ArraySpecs::MyArray[1, 2, 3].shift(2).should.instance_of?(Array)
     end
   end
 end
diff --git a/spec/ruby/core/array/shuffle_spec.rb b/spec/ruby/core/array/shuffle_spec.rb
index 7a2fed7d50..9bc9df73ac 100644
--- a/spec/ruby/core/array/shuffle_spec.rb
+++ b/spec/ruby/core/array/shuffle_spec.rb
@@ -10,7 +10,7 @@ describe "Array#shuffle" do
       s.sort.should == a
       different ||= (a != s)
     end
-    different.should be_true # Will fail once in a blue moon (4!^10)
+    different.should == true # Will fail once in a blue moon (4!^10)
   end
 
   it "is not destructive" do
@@ -22,13 +22,7 @@ describe "Array#shuffle" do
   end
 
   it "does not return subclass instances with Array subclass" do
-    ArraySpecs::MyArray[1, 2, 3].shuffle.should be_an_instance_of(Array)
-  end
-
-  it "attempts coercion via #to_hash" do
-    obj = mock('hash')
-    obj.should_receive(:to_hash).once.and_return({})
-    [2, 3].shuffle(obj)
+    ArraySpecs::MyArray[1, 2, 3].shuffle.should.instance_of?(Array)
   end
 
   it "calls #rand on the Object passed by the :random key in the arguments Hash" do
@@ -37,20 +31,24 @@ describe "Array#shuffle" do
 
     result = [1, 2].shuffle(random: obj)
     result.size.should == 2
-    result.should include(1, 2)
+    result.sort.should == [1, 2]
   end
 
   it "raises a NoMethodError if an object passed for the RNG does not define #rand" do
     obj = BasicObject.new
 
-    -> { [1, 2].shuffle(random: obj) }.should raise_error(NoMethodError)
+    -> { [1, 2].shuffle(random: obj) }.should.raise(NoMethodError)
   end
 
   it "accepts a Float for the value returned by #rand" do
     random = mock("array_shuffle_random")
     random.should_receive(:rand).at_least(1).times.and_return(0.3)
 
-    [1, 2].shuffle(random: random).should be_an_instance_of(Array)
+    [1, 2].shuffle(random: random).should.instance_of?(Array)
+  end
+
+  it "accepts a Random class for the value for random: argument" do
+    [1, 2].shuffle(random: Random).should.instance_of?(Array)
   end
 
   it "calls #to_int on the Object returned by #rand" do
@@ -59,7 +57,7 @@ describe "Array#shuffle" do
     random = mock("array_shuffle_random")
     random.should_receive(:rand).at_least(1).times.and_return(value)
 
-    [1, 2].shuffle(random: random).should be_an_instance_of(Array)
+    [1, 2].shuffle(random: random).should.instance_of?(Array)
   end
 
   it "raises a RangeError if the value is less than zero" do
@@ -68,16 +66,25 @@ describe "Array#shuffle" do
     random = mock("array_shuffle_random")
     random.should_receive(:rand).and_return(value)
 
-    -> { [1, 2].shuffle(random: random) }.should raise_error(RangeError)
+    -> { [1, 2].shuffle(random: random) }.should.raise(RangeError)
+  end
+
+  it "raises a RangeError if the value is equal to the Array size" do
+    value = mock("array_shuffle_random_value")
+    value.should_receive(:to_int).at_least(1).times.and_return(2)
+    random = mock("array_shuffle_random")
+    random.should_receive(:rand).at_least(1).times.and_return(value)
+
+    -> { [1, 2].shuffle(random: random) }.should.raise(RangeError)
   end
 
-  it "raises a RangeError if the value is equal to one" do
+  it "raises a RangeError if the value is greater than the Array size" do
     value = mock("array_shuffle_random_value")
-    value.should_receive(:to_int).at_least(1).times.and_return(1)
+    value.should_receive(:to_int).at_least(1).times.and_return(3)
     random = mock("array_shuffle_random")
     random.should_receive(:rand).at_least(1).times.and_return(value)
 
-    -> { [1, 2].shuffle(random: random) }.should raise_error(RangeError)
+    -> { [1, 2].shuffle(random: random) }.should.raise(RangeError)
   end
 end
 
@@ -91,12 +98,22 @@ describe "Array#shuffle!" do
       a.sort.should == [1, 2, 3, 4]
       different ||= (a != [1, 2, 3, 4])
     end
-    different.should be_true # Will fail once in a blue moon (4!^10)
-    a.should equal(original)
+    different.should == true # Will fail once in a blue moon (4!^10)
+    a.should.equal?(original)
+  end
+
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.shuffle! }.should.raise(FrozenError)
+    -> { ArraySpecs.empty_frozen_array.shuffle! }.should.raise(FrozenError)
+  end
+
+  it "matches CRuby with random:" do
+    %w[a b c].shuffle(random: Random.new(1)).should == %w[a c b]
+    (0..10).to_a.shuffle(random: Random.new(10)).should == [2, 6, 8, 5, 7, 10, 3, 1, 0, 4, 9]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.shuffle! }.should raise_error(frozen_error_class)
-    -> { ArraySpecs.empty_frozen_array.shuffle! }.should raise_error(frozen_error_class)
+  it "matches CRuby with srand" do
+    srand(123)
+    %w[a b c d e f g h i j k].shuffle.should == %w[a e f h i j d b g k c]
   end
 end
diff --git a/spec/ruby/core/array/size_spec.rb b/spec/ruby/core/array/size_spec.rb
index d68f956a83..83e8969012 100644
--- a/spec/ruby/core/array/size_spec.rb
+++ b/spec/ruby/core/array/size_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/length'
 
 describe "Array#size" do
-  it_behaves_like :array_length, :size
+  it "is an alias of Array#length" do
+    Array.instance_method(:size).should == Array.instance_method(:length)
+  end
 end
diff --git a/spec/ruby/core/array/slice_spec.rb b/spec/ruby/core/array/slice_spec.rb
index 16220bdf0d..230d1dc5d1 100644
--- a/spec/ruby/core/array/slice_spec.rb
+++ b/spec/ruby/core/array/slice_spec.rb
@@ -1,6 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/slice'
 
 describe "Array#slice!" do
   it "removes and return the element at index" do
@@ -116,8 +115,8 @@ describe "Array#slice!" do
     a.slice!(from .. to).should == [2, 3, 4]
     a.should == [1, 5]
 
-    -> { a.slice!("a" .. "b")  }.should raise_error(TypeError)
-    -> { a.slice!(from .. "b") }.should raise_error(TypeError)
+    -> { a.slice!("a" .. "b")  }.should.raise(TypeError)
+    -> { a.slice!(from .. "b") }.should.raise(TypeError)
   end
 
   it "returns last element for consecutive calls at zero index" do
@@ -150,11 +149,71 @@ describe "Array#slice!" do
     a.should == [1, 2]
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.slice!(0, 0) }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.slice!(0, 0) }.should.raise(FrozenError)
+  end
+
+  it "works with endless ranges" do
+    a = [1, 2, 3]
+    a.slice!(eval("(1..)")).should == [2, 3]
+    a.should == [1]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(2...)")).should == [3]
+    a.should == [1, 2]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(-2..)")).should == [2, 3]
+    a.should == [1]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(-1...)")).should == [3]
+    a.should == [1, 2]
+  end
+
+  it "works with beginless ranges" do
+    a = [0,1,2,3,4]
+    a.slice!((..3)).should == [0, 1, 2, 3]
+    a.should == [4]
+
+    a = [0,1,2,3,4]
+    a.slice!((...-2)).should == [0, 1, 2]
+    a.should == [3, 4]
+  end
+
+  describe "with a subclass of Array" do
+    before :each do
+      @array = ArraySpecs::MyArray[1, 2, 3, 4, 5]
+    end
+
+    it "returns a Array instance with [n, m]" do
+      @array.slice!(0, 2).should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n, m]" do
+      @array.slice!(-3, 2).should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [n..m]" do
+      @array.slice!(1..3).should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [n...m]" do
+      @array.slice!(1...3).should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n..-m]" do
+      @array.slice!(-3..-1).should.instance_of?(Array)
+    end
+
+    it "returns a Array instance with [-n...-m]" do
+      @array.slice!(-3...-1).should.instance_of?(Array)
+    end
   end
 end
 
 describe "Array#slice" do
-  it_behaves_like :array_slice, :slice
+  it "is an alias of Array#[]" do
+    Array.instance_method(:slice).should == Array.instance_method(:[])
+  end
 end
diff --git a/spec/ruby/core/array/sort_by_spec.rb b/spec/ruby/core/array/sort_by_spec.rb
index 045051d307..132abb028a 100644
--- a/spec/ruby/core/array/sort_by_spec.rb
+++ b/spec/ruby/core/array/sort_by_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Array#sort_by!" do
@@ -10,25 +11,30 @@ describe "Array#sort_by!" do
   end
 
   it "returns an Enumerator if not given a block" do
-    (1..10).to_a.sort_by!.should be_an_instance_of(Enumerator)
+    (1..10).to_a.sort_by!.should.instance_of?(Enumerator)
   end
 
   it "completes when supplied a block that always returns the same result" do
     a = [2, 3, 5, 1, 4]
     a.sort_by!{  1 }
-    a.should be_an_instance_of(Array)
+    a.should.instance_of?(Array)
     a.sort_by!{  0 }
-    a.should be_an_instance_of(Array)
+    a.should.instance_of?(Array)
     a.sort_by!{ -1 }
-    a.should be_an_instance_of(Array)
+    a.should.instance_of?(Array)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.sort_by! {}}.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.sort_by! {}}.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on an empty frozen array" do
-    -> { ArraySpecs.empty_frozen_array.sort_by! {}}.should raise_error(frozen_error_class)
+  it "raises a FrozenError on an empty frozen array" do
+    -> { ArraySpecs.empty_frozen_array.sort_by! {}}.should.raise(FrozenError)
+  end
+
+  it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+    enum = ArraySpecs.frozen_array.sort_by!
+    -> { enum.each {} }.should.raise(FrozenError)
   end
 
   it "returns the specified value when it would break in the given block" do
@@ -41,12 +47,39 @@ describe "Array#sort_by!" do
       ary.sort_by!{|x,y| break if x==i; x<=>y}
       ary
     }
-    partially_sorted.any?{|ary| ary != [1, 2, 3, 4, 5]}.should be_true
+    partially_sorted.any?{|ary| ary != [1, 2, 3, 4, 5]}.should == true
   end
 
   it "changes nothing when called on a single element array" do
     [1].sort_by!(&:to_s).should == [1]
   end
 
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.sort_by! { raise StandardError, 'Oops' }
+    rescue
+    end
+
+    a.should == [1, 2, 3]
+  end
+
+  it "doesn't change array if error is raised" do
+    a = [4, 3, 2, 1]
+    begin
+      a.sort_by! do |e|
+        raise StandardError, 'Oops' if e == 1
+        e
+      end
+    rescue StandardError
+    end
+
+    a.should == [4, 3, 2, 1]
+  end
+
   it_behaves_like :enumeratorized_with_origin_size, :sort_by!, [1,2,3]
 end
+
+describe "Array#sort_by!" do
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :sort_by!
+end
diff --git a/spec/ruby/core/array/sort_spec.rb b/spec/ruby/core/array/sort_spec.rb
index 6b84a82a48..27300c3385 100644
--- a/spec/ruby/core/array/sort_spec.rb
+++ b/spec/ruby/core/array/sort_spec.rb
@@ -42,7 +42,7 @@ describe "Array#sort" do
     a = [1, 2, 3]
     sorted = a.sort
     sorted.should == a
-    sorted.should_not equal(a)
+    sorted.should_not.equal?(a)
   end
 
   it "properly handles recursive arrays" do
@@ -58,9 +58,9 @@ describe "Array#sort" do
     b = ArraySpecs::MockForCompared.new
     c = ArraySpecs::MockForCompared.new
 
-    ArraySpecs::MockForCompared.compared?.should == false
+    ArraySpecs::MockForCompared.should_not.compared?
     [a, b, c].sort.should == [c, b, a]
-    ArraySpecs::MockForCompared.compared?.should == true
+    ArraySpecs::MockForCompared.should.compared?
   end
 
   it "does not deal with exceptions raised by unimplemented or incorrect #<=>" do
@@ -68,7 +68,7 @@ describe "Array#sort" do
 
     -> {
       [o, 1].sort
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "may take a block which is used to determine the order of objects a and b described as -1, 0 or +1" do
@@ -78,43 +78,43 @@ describe "Array#sort" do
   end
 
   it "raises an error when a given block returns nil" do
-    -> { [1, 2].sort {} }.should raise_error(ArgumentError)
+    -> { [1, 2].sort {} }.should.raise(ArgumentError)
   end
 
   it "does not call #<=> on contained objects when invoked with a block" do
     a = Array.new(25)
     (0...25).each {|i| a[i] = ArraySpecs::UFOSceptic.new }
 
-    a.sort { -1 }.should be_an_instance_of(Array)
+    a.sort { -1 }.should.instance_of?(Array)
   end
 
   it "does not call #<=> on elements when invoked with a block even if Array is large (Rubinius #412)" do
     a = Array.new(1500)
     (0...1500).each {|i| a[i] = ArraySpecs::UFOSceptic.new }
 
-    a.sort { -1 }.should be_an_instance_of(Array)
+    a.sort { -1 }.should.instance_of?(Array)
   end
 
   it "completes when supplied a block that always returns the same result" do
     a = [2, 3, 5, 1, 4]
-    a.sort {  1 }.should be_an_instance_of(Array)
-    a.sort {  0 }.should be_an_instance_of(Array)
-    a.sort { -1 }.should be_an_instance_of(Array)
+    a.sort {  1 }.should.instance_of?(Array)
+    a.sort {  0 }.should.instance_of?(Array)
+    a.sort { -1 }.should.instance_of?(Array)
   end
 
   it "does not freezes self during being sorted" do
     a = [1, 2, 3]
-    a.sort { |x,y| a.frozen?.should == false; x <=> y }
+    a.sort { |x,y| a.should_not.frozen?; x <=> y }
   end
 
   it "returns the specified value when it would break in the given block" do
     [1, 2, 3].sort{ break :a }.should == :a
   end
 
-  it "uses the sign of Bignum block results as the sort result" do
+  it "uses the sign of Integer block results as the sort result" do
     a = [1, 2, 5, 10, 7, -4, 12]
     begin
-      class Bignum;
+      class Integer
         alias old_spaceship <=>
         def <=>(other)
           raise
@@ -122,7 +122,7 @@ describe "Array#sort" do
       end
       a.sort {|n, m| (n - m) * (2 ** 200)}.should == [-4, 1, 2, 5, 7, 10, 12]
     ensure
-      class Bignum
+      class Integer
         alias <=> old_spaceship
       end
     end
@@ -132,11 +132,11 @@ describe "Array#sort" do
     a = [1, 2, 5, 10, 7, -4, 12]
     a.sort { |n, m| n - m }.should == [-4, 1, 2, 5, 7, 10, 12]
     a.sort { |n, m|
-      ArraySpecs::ComparableWithFixnum.new(n-m)
+      ArraySpecs::ComparableWithInteger.new(n-m)
     }.should == [-4, 1, 2, 5, 7, 10, 12]
     -> {
       a.sort { |n, m| (n - m).to_s }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "sorts an array that has a value shifted off without a block" do
@@ -155,7 +155,7 @@ describe "Array#sort" do
 
   it "raises an error if objects can't be compared" do
     a=[ArraySpecs::Uncomparable.new, ArraySpecs::Uncomparable.new]
-    -> {a.sort}.should raise_error(ArgumentError)
+    -> {a.sort}.should.raise(ArgumentError)
   end
 
   # From a strange Rubinius bug
@@ -166,7 +166,7 @@ describe "Array#sort" do
 
   it "does not return subclass instance on Array subclasses" do
     ary = ArraySpecs::MyArray[1, 2, 3]
-    ary.sort.should be_an_instance_of(Array)
+    ary.sort.should.instance_of?(Array)
   end
 end
 
@@ -184,13 +184,13 @@ describe "Array#sort!" do
 
   it "returns self if the order of elements changed" do
     a = [6, 7, 2, 3, 7]
-    a.sort!.should equal(a)
+    a.sort!.should.equal?(a)
     a.should == [2, 3, 6, 7, 7]
   end
 
   it "returns self even if makes no modification" do
     a = [1, 2, 3, 4, 5]
-    a.sort!.should equal(a)
+    a.sort!.should.equal?(a)
     a.should == [1, 2, 3, 4, 5]
   end
 
@@ -207,34 +207,34 @@ describe "Array#sort!" do
     b = ArraySpecs::MockForCompared.new
     c = ArraySpecs::MockForCompared.new
 
-    ArraySpecs::MockForCompared.compared?.should == false
+    ArraySpecs::MockForCompared.should_not.compared?
     [a, b, c].sort!.should == [c, b, a]
-    ArraySpecs::MockForCompared.compared?.should == true
+    ArraySpecs::MockForCompared.should.compared?
   end
 
   it "does not call #<=> on contained objects when invoked with a block" do
     a = Array.new(25)
     (0...25).each {|i| a[i] = ArraySpecs::UFOSceptic.new }
 
-    a.sort! { -1 }.should be_an_instance_of(Array)
+    a.sort! { -1 }.should.instance_of?(Array)
   end
 
   it "does not call #<=> on elements when invoked with a block even if Array is large (Rubinius #412)" do
     a = Array.new(1500)
     (0...1500).each {|i| a[i] = ArraySpecs::UFOSceptic.new }
 
-    a.sort! { -1 }.should be_an_instance_of(Array)
+    a.sort! { -1 }.should.instance_of?(Array)
   end
 
   it "completes when supplied a block that always returns the same result" do
     a = [2, 3, 5, 1, 4]
-    a.sort!{  1 }.should be_an_instance_of(Array)
-    a.sort!{  0 }.should be_an_instance_of(Array)
-    a.sort!{ -1 }.should be_an_instance_of(Array)
+    a.sort!{  1 }.should.instance_of?(Array)
+    a.sort!{  0 }.should.instance_of?(Array)
+    a.sort!{ -1 }.should.instance_of?(Array)
   end
 
-  it "raises a #{frozen_error_class} on a frozen array" do
-    -> { ArraySpecs.frozen_array.sort! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array" do
+    -> { ArraySpecs.frozen_array.sort! }.should.raise(FrozenError)
   end
 
   it "returns the specified value when it would break in the given block" do
@@ -247,6 +247,6 @@ describe "Array#sort!" do
       ary.sort!{|x,y| break if x==i; x<=>y}
       ary
     }
-    partially_sorted.any?{|ary| ary != [1, 2, 3, 4, 5]}.should be_true
+    partially_sorted.any?{|ary| ary != [1, 2, 3, 4, 5]}.should == true
   end
 end
diff --git a/spec/ruby/core/array/sum_spec.rb b/spec/ruby/core/array/sum_spec.rb
index 39c769d328..cd4ba4c2d8 100644
--- a/spec/ruby/core/array/sum_spec.rb
+++ b/spec/ruby/core/array/sum_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#sum" do
   it "returns the sum of elements" do
@@ -9,6 +10,39 @@ describe "Array#sum" do
     [1, 2, 3].sum { |i| i * 10 }.should == 60
   end
 
+  it "doesn't apply the block init" do
+    [1, 2, 3].sum(1) { |i| i * 10 }.should == 61
+  end
+
+  # https://bugs.ruby-lang.org/issues/12217
+  # https://github.com/ruby/ruby/blob/master/doc/ChangeLog/ChangeLog-2.4.0#L6208-L6214
+  it "uses Kahan's compensated summation algorithm for precise sum of float numbers" do
+    floats = [2.7800000000000002, 5.0, 2.5, 4.44, 3.89, 3.89, 4.44, 7.78, 5.0, 2.7800000000000002, 5.0, 2.5]
+    naive_sum = floats.reduce { |sum, e| sum + e }
+    naive_sum.should == 50.00000000000001
+    floats.sum.should == 50.0
+  end
+
+  it "handles infinite values and NaN" do
+    [1.0, Float::INFINITY].sum.should == Float::INFINITY
+    [1.0, -Float::INFINITY].sum.should == -Float::INFINITY
+    [1.0, Float::NAN].sum.should.nan?
+
+    [Float::INFINITY, 1.0].sum.should == Float::INFINITY
+    [-Float::INFINITY, 1.0].sum.should == -Float::INFINITY
+    [Float::NAN, 1.0].sum.should.nan?
+
+    [Float::NAN, Float::INFINITY].sum.should.nan?
+    [Float::INFINITY, Float::NAN].sum.should.nan?
+
+    [Float::INFINITY, -Float::INFINITY].sum.should.nan?
+    [-Float::INFINITY, Float::INFINITY].sum.should.nan?
+
+    [Float::INFINITY, Float::INFINITY].sum.should == Float::INFINITY
+    [-Float::INFINITY, -Float::INFINITY].sum.should == -Float::INFINITY
+    [Float::NAN, Float::NAN].sum.should.nan?
+  end
+
   it "returns init value if array is empty" do
     [].sum(-1).should == -1
   end
@@ -26,11 +60,11 @@ describe "Array#sum" do
   end
 
   it 'raises TypeError if any element are not numeric' do
-    -> { ["a"].sum }.should raise_error(TypeError)
+    -> { ["a"].sum }.should.raise(TypeError)
   end
 
   it 'raises TypeError if any element cannot be added to init value' do
-    -> { [1].sum([]) }.should raise_error(TypeError)
+    -> { [1].sum([]) }.should.raise(TypeError)
   end
 
   it "calls + to sum the elements" do
@@ -39,4 +73,16 @@ describe "Array#sum" do
     a.should_receive(:+).with(b).and_return(42)
     [b].sum(a).should == 42
   end
+
+  it "calls + on the init value" do
+    a = mock("a")
+    b = mock("b")
+    a.should_receive(:+).with(42).and_return(b)
+    [42].sum(a).should == b
+  end
+end
+
+describe "Array#sum" do
+  @value_to_return = -> _ { 1 }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :sum
 end
diff --git a/spec/ruby/core/array/take_spec.rb b/spec/ruby/core/array/take_spec.rb
index 0de99b0a7e..837c734b77 100644
--- a/spec/ruby/core/array/take_spec.rb
+++ b/spec/ruby/core/array/take_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#take" do
   it "returns the first specified number of elements" do
@@ -22,6 +23,10 @@ describe "Array#take" do
   end
 
   it "raises an ArgumentError when the argument is negative" do
-    ->{ [1].take(-3) }.should raise_error(ArgumentError)
+    ->{ [1].take(-3) }.should.raise(ArgumentError)
+  end
+
+  it 'returns a Array instance for Array subclasses' do
+    ArraySpecs::MyArray[1, 2, 3, 4, 5].take(1).should.instance_of?(Array)
   end
 end
diff --git a/spec/ruby/core/array/take_while_spec.rb b/spec/ruby/core/array/take_while_spec.rb
index f159e6f251..7811edab9e 100644
--- a/spec/ruby/core/array/take_while_spec.rb
+++ b/spec/ruby/core/array/take_while_spec.rb
@@ -1,4 +1,6 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#take_while" do
   it "returns all elements until the block returns false" do
@@ -12,4 +14,13 @@ describe "Array#take_while" do
   it "returns all elements until the block returns false" do
     [1, 2, false, 4].take_while{ |element| element }.should == [1, 2]
   end
+
+  it 'returns a Array instance for Array subclasses' do
+    ArraySpecs::MyArray[1, 2, 3, 4, 5].take_while { |n| n < 4 }.should.instance_of?(Array)
+  end
+end
+
+describe "Array#take_while" do
+  @value_to_return = -> _ { true }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :take_while
 end
diff --git a/spec/ruby/core/array/to_a_spec.rb b/spec/ruby/core/array/to_a_spec.rb
index 49d0a4782e..078de1638a 100644
--- a/spec/ruby/core/array/to_a_spec.rb
+++ b/spec/ruby/core/array/to_a_spec.rb
@@ -5,12 +5,12 @@ describe "Array#to_a" do
   it "returns self" do
     a = [1, 2, 3]
     a.to_a.should == [1, 2, 3]
-    a.should equal(a.to_a)
+    a.should.equal?(a.to_a)
   end
 
   it "does not return subclass instance on Array subclasses" do
     e = ArraySpecs::MyArray.new(1, 2)
-    e.to_a.should be_an_instance_of(Array)
+    e.to_a.should.instance_of?(Array)
     e.to_a.should == [1, 2]
   end
 
diff --git a/spec/ruby/core/array/to_ary_spec.rb b/spec/ruby/core/array/to_ary_spec.rb
index 314699b709..dc5193158d 100644
--- a/spec/ruby/core/array/to_ary_spec.rb
+++ b/spec/ruby/core/array/to_ary_spec.rb
@@ -4,9 +4,9 @@ require_relative 'fixtures/classes'
 describe "Array#to_ary" do
   it "returns self" do
     a = [1, 2, 3]
-    a.should equal(a.to_ary)
+    a.should.equal?(a.to_ary)
     a = ArraySpecs::MyArray[1, 2, 3]
-    a.should equal(a.to_ary)
+    a.should.equal?(a.to_ary)
   end
 
   it "properly handles recursive arrays" do
diff --git a/spec/ruby/core/array/to_h_spec.rb b/spec/ruby/core/array/to_h_spec.rb
index 46a79ba58b..1d626763c2 100644
--- a/spec/ruby/core/array/to_h_spec.rb
+++ b/spec/ruby/core/array/to_h_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#to_h" do
   it "converts empty array to empty hash" do
@@ -24,58 +25,67 @@ describe "Array#to_h" do
   end
 
   it "raises TypeError if an element is not an array" do
-    -> { [:x].to_h }.should raise_error(TypeError)
+    -> { [:x].to_h }.should.raise(TypeError)
   end
 
   it "raises ArgumentError if an element is not a [key, value] pair" do
-    -> { [[:x]].to_h }.should raise_error(ArgumentError)
+    -> { [[:x]].to_h }.should.raise(ArgumentError)
   end
 
   it "does not accept arguments" do
-    -> { [].to_h(:a, :b) }.should raise_error(ArgumentError)
+    -> { [].to_h(:a, :b) }.should.raise(ArgumentError)
   end
 
   it "produces a hash that returns nil for a missing element" do
-    [[:a, 1], [:b, 2]].to_h[:c].should be_nil
+    [[:a, 1], [:b, 2]].to_h[:c].should == nil
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a Hash" do
-        [:a, :b].to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          [:a, :b].to_h { |k| [k, k.to_s, 1] }
-        end.should raise_error(ArgumentError, /wrong array length at 0/)
-
-        -> do
-          [:a, :b].to_h { |k| [k] }
-        end.should raise_error(ArgumentError, /wrong array length at 0/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          [:a, :b].to_h { |k| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String at 0/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        [:a].to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          [:a].to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject at 0/)
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a Hash" do
+      [:a, :b].to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
+    end
+
+    it "passes to a block each element as a single argument" do
+      ScratchPad.record []
+      [[:a, 1], [:b, 2]].to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[[:a, 1]], [[:b, 2]]]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        [:a, :b].to_h { |k| [k, k.to_s, 1] }
+      end.should.raise(ArgumentError, /wrong array length at 0/)
+
+      -> do
+        [:a, :b].to_h { |k| [k] }
+      end.should.raise(ArgumentError, /wrong array length at 0/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        [:a, :b].to_h { |k| "not-array" }
+      end.should.raise(TypeError, /wrong element type String at 0/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      [:a].to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        [:a].to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject at 0/)
     end
   end
 end
+
+describe "Array#to_h" do
+  @value_to_return = -> e { [e, e.to_s] }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :to_h
+end
diff --git a/spec/ruby/core/array/to_s_spec.rb b/spec/ruby/core/array/to_s_spec.rb
index e8476702ec..483e14f902 100644
--- a/spec/ruby/core/array/to_s_spec.rb
+++ b/spec/ruby/core/array/to_s_spec.rb
@@ -1,8 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/join'
-require_relative 'shared/inspect'
 
 describe "Array#to_s" do
-  it_behaves_like :array_inspect, :to_s
+  it "is an alias of Array#inspect" do
+    Array.instance_method(:to_s).should == Array.instance_method(:inspect)
+  end
 end
diff --git a/spec/ruby/core/array/transpose_spec.rb b/spec/ruby/core/array/transpose_spec.rb
index b39077f4c9..d45e9c351c 100644
--- a/spec/ruby/core/array/transpose_spec.rb
+++ b/spec/ruby/core/array/transpose_spec.rb
@@ -32,7 +32,7 @@ describe "Array#transpose" do
   end
 
   it "raises a TypeError if the passed Argument does not respond to #to_ary" do
-    -> { [Object.new, [:a, :b]].transpose }.should raise_error(TypeError)
+    -> { [Object.new, [:a, :b]].transpose }.should.raise(TypeError)
   end
 
   it "does not call to_ary on array subclass elements" do
@@ -41,13 +41,13 @@ describe "Array#transpose" do
   end
 
   it "raises an IndexError if the arrays are not of the same length" do
-    -> { [[1, 2], [:a]].transpose }.should raise_error(IndexError)
+    -> { [[1, 2], [:a]].transpose }.should.raise(IndexError)
   end
 
   it "does not return subclass instance on Array subclasses" do
     result = ArraySpecs::MyArray[ArraySpecs::MyArray[1, 2, 3], ArraySpecs::MyArray[4, 5, 6]].transpose
-    result.should be_an_instance_of(Array)
-    result[0].should be_an_instance_of(Array)
-    result[1].should be_an_instance_of(Array)
+    result.should.instance_of?(Array)
+    result[0].should.instance_of?(Array)
+    result[1].should.instance_of?(Array)
   end
 end
diff --git a/spec/ruby/core/array/try_convert_spec.rb b/spec/ruby/core/array/try_convert_spec.rb
index 47b4722d80..3eaa0f4b7c 100644
--- a/spec/ruby/core/array/try_convert_spec.rb
+++ b/spec/ruby/core/array/try_convert_spec.rb
@@ -4,47 +4,47 @@ require_relative 'fixtures/classes'
 describe "Array.try_convert" do
   it "returns the argument if it's an Array" do
     x = Array.new
-    Array.try_convert(x).should equal(x)
+    Array.try_convert(x).should.equal?(x)
   end
 
   it "returns the argument if it's a kind of Array" do
     x = ArraySpecs::MyArray[]
-    Array.try_convert(x).should equal(x)
+    Array.try_convert(x).should.equal?(x)
   end
 
   it "returns nil when the argument does not respond to #to_ary" do
-    Array.try_convert(Object.new).should be_nil
+    Array.try_convert(Object.new).should == nil
   end
 
   it "sends #to_ary to the argument and returns the result if it's nil" do
     obj = mock("to_ary")
     obj.should_receive(:to_ary).and_return(nil)
-    Array.try_convert(obj).should be_nil
+    Array.try_convert(obj).should == nil
   end
 
   it "sends #to_ary to the argument and returns the result if it's an Array" do
     x = Array.new
     obj = mock("to_ary")
     obj.should_receive(:to_ary).and_return(x)
-    Array.try_convert(obj).should equal(x)
+    Array.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_ary to the argument and returns the result if it's a kind of Array" do
     x = ArraySpecs::MyArray[]
     obj = mock("to_ary")
     obj.should_receive(:to_ary).and_return(x)
-    Array.try_convert(obj).should equal(x)
+    Array.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_ary to the argument and raises TypeError if it's not a kind of Array" do
     obj = mock("to_ary")
     obj.should_receive(:to_ary).and_return(Object.new)
-    -> { Array.try_convert obj }.should raise_error(TypeError)
+    -> { Array.try_convert obj }.should raise_consistent_error(TypeError, "can't convert MockObject into Array (MockObject#to_ary gives Object)")
   end
 
   it "does not rescue exceptions raised by #to_ary" do
     obj = mock("to_ary")
     obj.should_receive(:to_ary).and_raise(RuntimeError)
-    -> { Array.try_convert obj }.should raise_error(RuntimeError)
+    -> { Array.try_convert obj }.should.raise(RuntimeError)
   end
 end
diff --git a/spec/ruby/core/array/union_spec.rb b/spec/ruby/core/array/union_spec.rb
index 1dca47696d..110894e83d 100644
--- a/spec/ruby/core/array/union_spec.rb
+++ b/spec/ruby/core/array/union_spec.rb
@@ -6,22 +6,20 @@ describe "Array#|" do
   it_behaves_like :array_binary_union, :|
 end
 
-ruby_version_is "2.6" do
-  describe "Array#union" do
-    it_behaves_like :array_binary_union, :union
+describe "Array#union" do
+  it_behaves_like :array_binary_union, :union
 
-    it "returns unique elements when given no argument" do
-      x = [1, 2, 3, 2]
-      x.union.should == [1, 2, 3]
-    end
+  it "returns unique elements when given no argument" do
+    x = [1, 2, 3, 2]
+    x.union.should == [1, 2, 3]
+  end
 
-    it "does not return subclass instances for Array subclasses" do
-      ArraySpecs::MyArray[1, 2, 3].union.should be_an_instance_of(Array)
-    end
+  it "does not return subclass instances for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].union.should.instance_of?(Array)
+  end
 
-    it "accepts multiple arguments" do
-      x = [1, 2, 3]
-      x.union(x, x, x, x, [3, 4], x).should == [1, 2, 3, 4]
-    end
+  it "accepts multiple arguments" do
+    x = [1, 2, 3]
+    x.union(x, x, x, x, [3, 4], x).should == [1, 2, 3, 4]
   end
 end
diff --git a/spec/ruby/core/array/uniq_spec.rb b/spec/ruby/core/array/uniq_spec.rb
index c9bdd3dacd..0289bee7c2 100644
--- a/spec/ruby/core/array/uniq_spec.rb
+++ b/spec/ruby/core/array/uniq_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/iterable_and_tolerating_size_increasing'
 
 describe "Array#uniq" do
   it "returns an array with no duplicates" do
@@ -45,10 +46,6 @@ describe "Array#uniq" do
       obj.should_receive(:hash).at_least(1).and_return(0)
 
       def obj.eql?(o)
-        # It's undefined whether the impl does a[0].eql?(a[1]) or
-        # a[1].eql?(a[0]) so we taint both.
-        taint
-        o.taint
         false
       end
 
@@ -56,18 +53,12 @@ describe "Array#uniq" do
     end
 
     a.uniq.should == a
-    a[0].tainted?.should == true
-    a[1].tainted?.should == true
 
     a = Array.new(2) do
       obj = mock('0')
       obj.should_receive(:hash).at_least(1).and_return(0)
 
       def obj.eql?(o)
-        # It's undefined whether the impl does a[0].eql?(a[1]) or
-        # a[1].eql?(a[0]) so we taint both.
-        taint
-        o.taint
         true
       end
 
@@ -75,8 +66,6 @@ describe "Array#uniq" do
     end
 
     a.uniq.size.should == 1
-    a[0].tainted?.should == true
-    a[1].tainted?.should == true
   end
 
   it "compares elements based on the value returned from the block" do
@@ -96,8 +85,8 @@ describe "Array#uniq" do
     [false, nil, 42].uniq { :bar }.should == [false]
   end
 
-  it "returns subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].uniq.should be_an_instance_of(ArraySpecs::MyArray)
+  it "returns Array instance on Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].uniq.should.instance_of?(Array)
   end
 
   it "properly handles an identical item even when its #eql? isn't reflexive" do
@@ -135,6 +124,11 @@ describe "Array#uniq" do
   end
 end
 
+describe "Array#uniq" do
+  @value_to_return = -> e { e }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :uniq
+end
+
 describe "Array#uniq!" do
   it "modifies the array in place" do
     a = [ "a", "a", "b", "b", "c" ]
@@ -144,7 +138,7 @@ describe "Array#uniq!" do
 
   it "returns self" do
     a = [ "a", "a", "b", "b", "c" ]
-    a.should equal(a.uniq!)
+    a.should.equal?(a.uniq!)
   end
 
   it "properly handles recursive arrays" do
@@ -188,20 +182,20 @@ describe "Array#uniq!" do
     [ "a", "b", "c" ].uniq!.should == nil
   end
 
-  it "raises a #{frozen_error_class} on a frozen array when the array is modified" do
+  it "raises a FrozenError on a frozen array when the array is modified" do
     dup_ary = [1, 1, 2]
     dup_ary.freeze
-    -> { dup_ary.uniq! }.should raise_error(frozen_error_class)
+    -> { dup_ary.uniq! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen array when the array would not be modified" do
-    -> { ArraySpecs.frozen_array.uniq!}.should raise_error(frozen_error_class)
-    -> { ArraySpecs.empty_frozen_array.uniq!}.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen array when the array would not be modified" do
+    -> { ArraySpecs.frozen_array.uniq!}.should.raise(FrozenError)
+    -> { ArraySpecs.empty_frozen_array.uniq!}.should.raise(FrozenError)
   end
 
   it "doesn't yield to the block on a frozen array" do
-    -> { ArraySpecs.frozen_array.uniq!{ raise RangeError, "shouldn't yield"}}.should raise_error(frozen_error_class)
+    -> { ArraySpecs.frozen_array.uniq!{ raise RangeError, "shouldn't yield"}}.should.raise(FrozenError)
   end
 
   it "compares elements based on the value returned from the block" do
@@ -218,4 +212,32 @@ describe "Array#uniq!" do
     a.uniq!
     a.should == [x]
   end
+
+  it "does not truncate the array is the block raises an exception" do
+    a = [1, 2, 3]
+    begin
+      a.send(@method) { raise StandardError, 'Oops' }
+    rescue
+    end
+
+    a.should == [1, 2, 3]
+  end
+
+  it "doesn't change array if error is raised" do
+    a = [1, 1, 2, 2, 3, 3, 4, 4]
+    begin
+      a.send(@method) do |e|
+        raise StandardError, 'Oops' if e == 3
+        e
+      end
+    rescue StandardError
+    end
+
+    a.should == [1, 1, 2, 2, 3, 3, 4, 4]
+  end
+end
+
+describe "Array#uniq!" do
+  @value_to_return = -> e { e }
+  it_behaves_like :array_iterable_and_tolerating_size_increasing, :uniq!
 end
diff --git a/spec/ruby/core/array/unshift_spec.rb b/spec/ruby/core/array/unshift_spec.rb
index b8b675e5f8..c190db4d02 100644
--- a/spec/ruby/core/array/unshift_spec.rb
+++ b/spec/ruby/core/array/unshift_spec.rb
@@ -1,7 +1,67 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/unshift'
 
 describe "Array#unshift" do
-  it_behaves_like :array_unshift, :unshift
+  it "prepends object to the original array" do
+    a = [1, 2, 3]
+    a.unshift("a").should.equal?(a)
+    a.should == ['a', 1, 2, 3]
+    a.unshift.should.equal?(a)
+    a.should == ['a', 1, 2, 3]
+    a.unshift(5, 4, 3)
+    a.should == [5, 4, 3, 'a', 1, 2, 3]
+
+    # shift all but one element
+    a = [1, 2]
+    a.shift
+    a.unshift(3, 4)
+    a.should == [3, 4, 2]
+
+    # now shift all elements
+    a.shift
+    a.shift
+    a.shift
+    a.unshift(3, 4)
+    a.should == [3, 4]
+  end
+
+  it "returns self" do
+    a = [1, 2, 3]
+    a.unshift("a").should.equal?(a)
+  end
+
+  it "quietly ignores unshifting nothing" do
+    [].unshift.should == []
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.unshift(:new).should == [:new, empty]
+
+    array = ArraySpecs.recursive_array
+    array.unshift(:new)
+    array[0..5].should == [:new, 1, 'two', 3.0, array, array]
+  end
+
+  it "raises a FrozenError on a frozen array when the array is modified" do
+    -> { ArraySpecs.frozen_array.unshift(1) }.should.raise(FrozenError)
+  end
+
+  # see [ruby-core:23666]
+  it "raises a FrozenError on a frozen array when the array would not be modified" do
+    -> { ArraySpecs.frozen_array.unshift }.should.raise(FrozenError)
+  end
+
+  # https://github.com/truffleruby/truffleruby/issues/2772
+  it "doesn't rely on Array#[]= so it can be overridden" do
+    subclass = Class.new(Array) do
+      def []=(*)
+        raise "[]= is called"
+      end
+    end
+
+    array = subclass.new
+    array.unshift(1)
+    array.should == [1]
+  end
 end
diff --git a/spec/ruby/core/array/values_at_spec.rb b/spec/ruby/core/array/values_at_spec.rb
index 13860150bb..e11e7e4451 100644
--- a/spec/ruby/core/array/values_at_spec.rb
+++ b/spec/ruby/core/array/values_at_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
+# Should be synchronized with core/struct/values_at_spec.rb
 describe "Array#values_at" do
   it "returns an array of elements at the indexes when passed indexes" do
     [1, 2, 3, 4, 5].values_at().should == []
@@ -58,6 +59,16 @@ describe "Array#values_at" do
   end
 
   it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].values_at(0, 1..2, 1).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].values_at(0, 1..2, 1).should.instance_of?(Array)
+  end
+
+  it "works when given endless ranges" do
+    [1, 2, 3, 4].values_at(eval("(1..)")).should == [2, 3, 4]
+    [1, 2, 3, 4].values_at(eval("(3...)")).should == [4]
+  end
+
+  it "works when given beginless ranges" do
+    [1, 2, 3, 4].values_at((..2)).should == [1, 2, 3]
+    [1, 2, 3, 4].values_at((...2)).should == [1, 2]
   end
 end
diff --git a/spec/ruby/core/array/zip_spec.rb b/spec/ruby/core/array/zip_spec.rb
index af4013debe..3ccdf143d6 100644
--- a/spec/ruby/core/array/zip_spec.rb
+++ b/spec/ruby/core/array/zip_spec.rb
@@ -60,6 +60,12 @@ describe "Array#zip" do
   end
 
   it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].zip(["a", "b"]).should be_an_instance_of(Array)
+    ArraySpecs::MyArray[1, 2, 3].zip(["a", "b"]).should.instance_of?(Array)
+  end
+
+  it "raises TypeError when some argument isn't Array and doesn't respond to #to_ary and #to_enum" do
+    -> { [1, 2, 3].zip(Object.new) }.should.raise(TypeError, "wrong argument type Object (must respond to :each)")
+    -> { [1, 2, 3].zip(1) }.should.raise(TypeError, "wrong argument type Integer (must respond to :each)")
+    -> { [1, 2, 3].zip(true) }.should.raise(TypeError, "wrong argument type TrueClass (must respond to :each)")
   end
 end
diff --git a/spec/ruby/core/basicobject/__send___spec.rb b/spec/ruby/core/basicobject/__send___spec.rb
index 005b1d0d90..2f814e448c 100644
--- a/spec/ruby/core/basicobject/__send___spec.rb
+++ b/spec/ruby/core/basicobject/__send___spec.rb
@@ -3,7 +3,7 @@ require_relative '../../shared/basicobject/send'
 
 describe "BasicObject#__send__" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:__send__)
+    BasicObject.public_instance_methods(false).should.include?(:__send__)
   end
 
   it_behaves_like :basicobject_send, :__send__
diff --git a/spec/ruby/core/basicobject/basicobject_spec.rb b/spec/ruby/core/basicobject/basicobject_spec.rb
index 27a322e72c..af28de0687 100644
--- a/spec/ruby/core/basicobject/basicobject_spec.rb
+++ b/spec/ruby/core/basicobject/basicobject_spec.rb
@@ -8,23 +8,23 @@ describe "BasicObject" do
   end
 
   it "raises NameError when referencing built-in constants" do
-    -> { class BasicObjectSpecs::BOSubclass; Kernel; end }.should raise_error(NameError)
+    -> { class BasicObjectSpecs::BOSubclass; Kernel; end }.should.raise(NameError)
   end
 
   it "does not define built-in constants (according to const_defined?)" do
-    BasicObject.const_defined?(:Kernel).should be_false
+    BasicObject.const_defined?(:Kernel).should == false
   end
 
   it "does not define built-in constants (according to defined?)" do
-    BasicObjectSpecs::BOSubclass.kernel_defined?.should be_nil
+    BasicObjectSpecs::BOSubclass.kernel_defined?.should == nil
   end
 
   it "is included in Object's list of constants" do
-    Object.constants(false).should include(:BasicObject)
+    Object.constants(false).should.include?(:BasicObject)
   end
 
   it "includes itself in its list of constants" do
-    BasicObject.constants(false).should include(:BasicObject)
+    BasicObject.constants(false).should.include?(:BasicObject)
   end
 end
 
@@ -34,11 +34,11 @@ describe "BasicObject metaclass" do
   end
 
   it "is an instance of Class" do
-    @meta.should be_an_instance_of(Class)
+    @meta.should.instance_of?(Class)
   end
 
   it "has Class as superclass" do
-    @meta.superclass.should equal(Class)
+    @meta.superclass.should.equal?(Class)
   end
 
   it "contains methods for the BasicObject class" do
@@ -57,11 +57,11 @@ describe "BasicObject instance metaclass" do
   end
 
   it "is an instance of Class" do
-    @meta.should be_an_instance_of(Class)
+    @meta.should.instance_of?(Class)
   end
 
   it "has BasicObject as superclass" do
-    @meta.superclass.should equal(BasicObject)
+    @meta.superclass.should.equal?(BasicObject)
   end
 
   it "contains methods defined for the BasicObject instance" do
@@ -85,7 +85,7 @@ describe "BasicObject subclass" do
 
   describe "BasicObject references" do
     it "can refer to BasicObject from within itself" do
-      -> { BasicObject::BasicObject }.should_not raise_error
+      -> { BasicObject::BasicObject }.should_not.raise
     end
   end
 end
diff --git a/spec/ruby/core/basicobject/equal_spec.rb b/spec/ruby/core/basicobject/equal_spec.rb
index 3c1ad56d4a..c0f41dc0c0 100644
--- a/spec/ruby/core/basicobject/equal_spec.rb
+++ b/spec/ruby/core/basicobject/equal_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../shared/kernel/equal'
 
 describe "BasicObject#equal?" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:equal?)
+    BasicObject.public_instance_methods(false).should.include?(:equal?)
   end
 
   it_behaves_like :object_equal, :equal?
@@ -11,9 +11,11 @@ describe "BasicObject#equal?" do
   it "is unaffected by overriding __id__" do
     o1 = mock("object")
     o2 = mock("object")
-    def o1.__id__; 10; end
-    def o2.__id__; 10; end
-    o1.equal?(o2).should be_false
+    suppress_warning {
+      def o1.__id__; 10; end
+      def o2.__id__; 10; end
+    }
+    o1.equal?(o2).should == false
   end
 
   it "is unaffected by overriding object_id" do
@@ -21,7 +23,7 @@ describe "BasicObject#equal?" do
     o1.stub!(:object_id).and_return(10)
     o2 = mock("object")
     o2.stub!(:object_id).and_return(10)
-    o1.equal?(o2).should be_false
+    o1.equal?(o2).should == false
   end
 
   it "is unaffected by overriding ==" do
@@ -29,12 +31,12 @@ describe "BasicObject#equal?" do
     o1 = mock("object")
     o1.stub!(:==).and_return(true)
     o2 = mock("object")
-    o1.equal?(o2).should be_false
+    o1.equal?(o2).should == false
 
     # same objects, overriding == to return false
     o3 = mock("object")
     o3.stub!(:==).and_return(false)
-    o3.equal?(o3).should be_true
+    o3.equal?(o3).should == true
   end
 
   it "is unaffected by overriding eql?" do
@@ -42,11 +44,11 @@ describe "BasicObject#equal?" do
     o1 = mock("object")
     o1.stub!(:eql?).and_return(true)
     o2 = mock("object")
-    o1.equal?(o2).should be_false
+    o1.equal?(o2).should == false
 
     # same objects, overriding eql? to return false
     o3 = mock("object")
     o3.stub!(:eql?).and_return(false)
-    o3.equal?(o3).should be_true
+    o3.equal?(o3).should == true
   end
 end
diff --git a/spec/ruby/core/basicobject/equal_value_spec.rb b/spec/ruby/core/basicobject/equal_value_spec.rb
index 6c825513c1..eb951a8305 100644
--- a/spec/ruby/core/basicobject/equal_value_spec.rb
+++ b/spec/ruby/core/basicobject/equal_value_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../shared/kernel/equal'
 
 describe "BasicObject#==" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:==)
+    BasicObject.public_instance_methods(false).should.include?(:==)
   end
 
   it_behaves_like :object_equal, :==
diff --git a/spec/ruby/core/basicobject/fixtures/classes.rb b/spec/ruby/core/basicobject/fixtures/classes.rb
index d1785afe31..ed5a2dda17 100644
--- a/spec/ruby/core/basicobject/fixtures/classes.rb
+++ b/spec/ruby/core/basicobject/fixtures/classes.rb
@@ -15,8 +15,231 @@ module BasicObjectSpecs
     include InstExec
   end
 
-  module InstEvalCVar
-    instance_eval { @@count = 2 }
+  module InstEval
+    module CVar
+      module Get
+        class ReceiverScope
+          @@cvar = :value_defined_in_receiver_scope
+        end
+
+        class BlockDefinitionScope
+          @@cvar = :value_defined_in_block_definition_scope
+
+          def block
+            -> * { @@cvar }
+          end
+        end
+
+        class CallerScope
+          @@cvar = :value_defined_in_caller_scope
+
+          def get_class_variable_with_string(obj)
+            obj.instance_eval("@@cvar")
+          end
+
+          def get_class_variable_with_block(obj, block)
+            obj.instance_eval(&block)
+          end
+        end
+
+        class CallerWithoutCVarScope
+          def get_class_variable_with_string(obj)
+            obj.instance_eval("@@cvar")
+          end
+        end
+
+        ReceiverWithCVarDefinedInSingletonClass = Class.new.new.tap do |obj|
+          obj.singleton_class.class_variable_set(:@@cvar, :value_defined_in_receiver_singleton_class)
+        end
+      end
+
+      module Set
+        class ReceiverScope
+        end
+
+        class BlockDefinitionScope
+          def self.get_class_variable
+            @@cvar
+          end
+
+          def block_to_assign(value)
+            -> * { @@cvar = value }
+          end
+        end
+
+        class CallerScope
+          def self.get_class_variable
+            @@cvar
+          end
+
+          def set_class_variable_with_string(obj, value)
+            obj.instance_eval("@@cvar=#{value.inspect}")
+          end
+
+          def set_class_variable_with_block(obj, block)
+            obj.instance_eval(&block)
+          end
+        end
+      end
+    end
+  end
+
+  module InstEval
+    module Constants
+      module ConstantInReceiverSingletonClass
+        module ReceiverScope
+          FOO = :ReceiverScope
+
+          class ReceiverParent
+            FOO = :ReceiverParent
+          end
+
+          class Receiver < ReceiverParent
+            FOO = :Receiver
+
+            def initialize
+              self.singleton_class.const_set(:FOO, :singleton_class)
+            end
+          end
+        end
+
+        module CallerScope
+          FOO = :CallerScope
+
+          class CallerParent
+            FOO = :CallerParent
+          end
+
+          class Caller < CallerParent
+            FOO = :Caller
+
+            def get_constant_with_string(receiver)
+              receiver.instance_eval("FOO")
+            end
+          end
+        end
+      end
+
+      module ConstantInReceiverClass
+        module ReceiverScope
+          FOO = :ReceiverScope
+
+          class ReceiverParent
+            FOO = :ReceiverParent
+          end
+
+          class Receiver < ReceiverParent
+            FOO = :Receiver
+          end
+        end
+
+        module CallerScope
+          FOO = :CallerScope
+
+          class CallerParent
+            FOO = :CallerParent
+          end
+
+          class Caller < CallerParent
+            FOO = :Caller
+
+            def get_constant_with_string(receiver)
+              receiver.instance_eval("FOO")
+            end
+          end
+        end
+      end
+
+      module ConstantInCallerClass
+        module ReceiverScope
+          FOO = :ReceiverScope
+
+          class ReceiverParent
+            FOO = :ReceiverParent
+          end
+
+          class Receiver < ReceiverParent
+            # FOO is not declared in a receiver class
+          end
+        end
+
+        module CallerScope
+          FOO = :CallerScope
+
+          class CallerParent
+            FOO = :CallerParent
+          end
+
+          class Caller < CallerParent
+            FOO = :Caller
+
+            def get_constant_with_string(receiver)
+              receiver.instance_eval("FOO")
+            end
+          end
+        end
+      end
+
+      module ConstantInCallerOuterScopes
+        module ReceiverScope
+          FOO = :ReceiverScope
+
+          class ReceiverParent
+            FOO = :ReceiverParent
+          end
+
+          class Receiver < ReceiverParent
+            # FOO is not declared in a receiver class
+          end
+        end
+
+        module CallerScope
+          FOO = :CallerScope
+
+          class CallerParent
+            FOO = :CallerParent
+          end
+
+          class Caller < CallerParent
+            # FOO is not declared in a caller class
+
+            def get_constant_with_string(receiver)
+              receiver.instance_eval("FOO")
+            end
+          end
+        end
+      end
+
+      module ConstantInReceiverParentClass
+        module ReceiverScope
+          FOO = :ReceiverScope
+
+          class ReceiverParent
+            FOO = :ReceiverParent
+          end
+
+          class Receiver < ReceiverParent
+            # FOO is not declared in a receiver class
+          end
+        end
+
+        module CallerScope
+          # FOO is not declared in a caller outer scopes
+
+          class CallerParent
+            FOO = :CallerParent
+          end
+
+          class Caller < CallerParent
+            # FOO is not declared in a caller class
+
+            def get_constant_with_string(receiver)
+              receiver.instance_eval("FOO")
+            end
+          end
+        end
+      end
+    end
   end
 
   class InstEvalConst
@@ -26,7 +249,6 @@ module BasicObjectSpecs
   module InstEvalOuter
     module Inner
       obj = InstEvalConst.new
-      X_BY_STR = obj.instance_eval("INST_EVAL_CONST_X") rescue nil
       X_BY_BLOCK = obj.instance_eval { INST_EVAL_CONST_X } rescue nil
     end
   end
diff --git a/spec/ruby/core/basicobject/initialize_spec.rb b/spec/ruby/core/basicobject/initialize_spec.rb
index b7ce73ffd5..09e86676b6 100644
--- a/spec/ruby/core/basicobject/initialize_spec.rb
+++ b/spec/ruby/core/basicobject/initialize_spec.rb
@@ -2,12 +2,12 @@ require_relative '../../spec_helper'
 
 describe "BasicObject#initialize" do
   it "is a private instance method" do
-    BasicObject.should have_private_instance_method(:initialize)
+    BasicObject.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "does not accept arguments" do
     -> {
       BasicObject.new("This", "makes it easier", "to call super", "from other constructors")
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/basicobject/instance_eval_spec.rb b/spec/ruby/core/basicobject/instance_eval_spec.rb
index d3dd05b745..124d179b5a 100644
--- a/spec/ruby/core/basicobject/instance_eval_spec.rb
+++ b/spec/ruby/core/basicobject/instance_eval_spec.rb
@@ -7,25 +7,31 @@ describe "BasicObject#instance_eval" do
   end
 
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:instance_eval)
+    BasicObject.public_instance_methods(false).should.include?(:instance_eval)
   end
 
   it "sets self to the receiver in the context of the passed block" do
     a = BasicObject.new
-    a.instance_eval { self }.equal?(a).should be_true
+    a.instance_eval { self }.equal?(a).should == true
   end
 
   it "evaluates strings" do
     a = BasicObject.new
-    a.instance_eval('self').equal?(a).should be_true
+    a.instance_eval('self').equal?(a).should == true
   end
 
-  it "expects a block with no arguments" do
-    -> { "hola".instance_eval }.should raise_error(ArgumentError)
+  it "raises an ArgumentError when no arguments and no block are given" do
+    -> { "hola".instance_eval }.should.raise(ArgumentError, "wrong number of arguments (given 0, expected 1..3)")
   end
 
-  it "takes no arguments with a block" do
-    -> { "hola".instance_eval(4, 5) {|a,b| a + b } }.should raise_error(ArgumentError)
+  it "raises an ArgumentError when a block and normal arguments are given" do
+    -> { "hola".instance_eval(4, 5) {|a,b| a + b } }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 0)")
+  end
+
+  it "raises an ArgumentError when more than 3 arguments are given" do
+    -> {
+      "hola".instance_eval("1 + 1", "some file", 0, "bogus")
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 1..3)")
   end
 
   it "yields the object to the block" do
@@ -45,7 +51,7 @@ describe "BasicObject#instance_eval" do
       end
     end
     f.foo.should == 1
-    -> { Object.new.foo }.should raise_error(NoMethodError)
+    -> { Object.new.foo }.should.raise(NoMethodError)
   end
 
   it "preserves self in the original block when passed a block argument" do
@@ -65,9 +71,9 @@ describe "BasicObject#instance_eval" do
 
   it "binds self to the receiver" do
     s = "hola"
-    (s == s.instance_eval { self }).should be_true
+    (s == s.instance_eval { self }).should == true
     o = mock('o')
-    (o == o.instance_eval("self")).should be_true
+    (o == o.instance_eval("self")).should == true
   end
 
   it "executes in the context of the receiver" do
@@ -78,11 +84,28 @@ describe "BasicObject#instance_eval" do
 
   end
 
+  it "uses the caller location as default location" do
+    f = Object.new
+    f.instance_eval("[__FILE__, __LINE__]").should == ["(eval at #{__FILE__}:#{__LINE__})", 1]
+  end
+
   it "has access to receiver's instance variables" do
     BasicObjectSpecs::IVars.new.instance_eval { @secret }.should == 99
     BasicObjectSpecs::IVars.new.instance_eval("@secret").should == 99
   end
 
+  it "raises TypeError for frozen objects when tries to set receiver's instance variables" do
+    -> { nil.instance_eval { @foo = 42 } }.should.raise(FrozenError, "can't modify frozen NilClass: nil")
+    -> { true.instance_eval { @foo = 42 } }.should.raise(FrozenError, "can't modify frozen TrueClass: true")
+    -> { false.instance_eval { @foo = 42 } }.should.raise(FrozenError, "can't modify frozen FalseClass: false")
+    -> { 1.instance_eval { @foo = 42 } }.should.raise(FrozenError, "can't modify frozen Integer: 1")
+    -> { :symbol.instance_eval { @foo = 42 } }.should.raise(FrozenError, "can't modify frozen Symbol: :symbol")
+
+    obj = Object.new
+    obj.freeze
+    -> { obj.instance_eval { @foo = 42 } }.should.raise(FrozenError)
+  end
+
   it "treats block-local variables as local to the block" do
     prc = instance_eval <<-CODE
       proc do |x, prc|
@@ -99,56 +122,118 @@ describe "BasicObject#instance_eval" do
     prc.call(false, prc).should == 1
   end
 
-  it "sets class variables in the receiver" do
-    BasicObjectSpecs::InstEvalCVar.class_variables.should include(:@@count)
-    BasicObjectSpecs::InstEvalCVar.send(:class_variable_get, :@@count).should == 2
-  end
-
   it "makes the receiver metaclass the scoped class when used with a string" do
     obj = Object.new
     obj.instance_eval %{
       class B; end
       B
     }
-    obj.singleton_class.const_get(:B).should be_an_instance_of(Class)
+    obj.singleton_class.const_get(:B).should.instance_of?(Class)
   end
 
-  it "gets constants in the receiver if a string given" do
-    BasicObjectSpecs::InstEvalOuter::Inner::X_BY_STR.should == 2
+  describe "constants lookup when a String given" do
+    it "looks in the receiver singleton class first" do
+      receiver = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverSingletonClass::ReceiverScope::Receiver.new
+      caller = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverSingletonClass::CallerScope::Caller.new
+
+      caller.get_constant_with_string(receiver).should == :singleton_class
+    end
+
+    it "looks in the receiver class next" do
+      receiver = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverClass::ReceiverScope::Receiver.new
+      caller = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverClass::CallerScope::Caller.new
+
+      caller.get_constant_with_string(receiver).should == :Receiver
+    end
+
+    it "looks in the caller class next" do
+      receiver = BasicObjectSpecs::InstEval::Constants::ConstantInCallerClass::ReceiverScope::Receiver.new
+      caller = BasicObjectSpecs::InstEval::Constants::ConstantInCallerClass::CallerScope::Caller.new
+
+      caller.get_constant_with_string(receiver).should == :Caller
+    end
+
+    it "looks in the caller outer scopes next" do
+      receiver = BasicObjectSpecs::InstEval::Constants::ConstantInCallerOuterScopes::ReceiverScope::Receiver.new
+      caller = BasicObjectSpecs::InstEval::Constants::ConstantInCallerOuterScopes::CallerScope::Caller.new
+
+      caller.get_constant_with_string(receiver).should == :CallerScope
+    end
+
+    it "looks in the receiver class hierarchy next" do
+      receiver = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverParentClass::ReceiverScope::Receiver.new
+      caller = BasicObjectSpecs::InstEval::Constants::ConstantInReceiverParentClass::CallerScope::Caller.new
+
+      caller.get_constant_with_string(receiver).should == :ReceiverParent
+    end
   end
 
   it "doesn't get constants in the receiver if a block given" do
-    BasicObjectSpecs::InstEvalOuter::Inner::X_BY_BLOCK.should be_nil
+    BasicObjectSpecs::InstEvalOuter::Inner::X_BY_BLOCK.should == nil
   end
 
   it "raises a TypeError when defining methods on an immediate" do
     -> do
       1.instance_eval { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
     -> do
       :foo.instance_eval { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
-quarantine! do # Not clean, leaves cvars lying around to break other specs
-  it "scopes class var accesses in the caller when called on a Fixnum" do
-    # Fixnum can take instance vars
-    Fixnum.class_eval "@@__tmp_instance_eval_spec = 1"
-    (defined? @@__tmp_instance_eval_spec).should be_nil
+  describe "class variables lookup" do
+    it "gets class variables in the caller class when called with a String" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Get::ReceiverScope.new
+      caller = BasicObjectSpecs::InstEval::CVar::Get::CallerScope.new
+
+      caller.get_class_variable_with_string(receiver).should == :value_defined_in_caller_scope
+    end
+
+    it "gets class variables in the block definition scope when called with a block" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Get::ReceiverScope.new
+      caller = BasicObjectSpecs::InstEval::CVar::Get::CallerScope.new
+      block = BasicObjectSpecs::InstEval::CVar::Get::BlockDefinitionScope.new.block
+
+      caller.get_class_variable_with_block(receiver, block).should == :value_defined_in_block_definition_scope
+    end
+
+    it "sets class variables in the caller class when called with a String" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Set::ReceiverScope.new
+      caller = BasicObjectSpecs::InstEval::CVar::Set::CallerScope.new
 
-    @@__tmp_instance_eval_spec = 2
-    1.instance_eval { @@__tmp_instance_eval_spec }.should == 2
-    Fixnum.__send__(:remove_class_variable, :@@__tmp_instance_eval_spec)
+      caller.set_class_variable_with_string(receiver, 1)
+      BasicObjectSpecs::InstEval::CVar::Set::CallerScope.get_class_variable.should == 1
+    end
+
+    it "sets class variables in the block definition scope when called with a block" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Set::ReceiverScope.new
+      caller = BasicObjectSpecs::InstEval::CVar::Set::CallerScope.new
+      block = BasicObjectSpecs::InstEval::CVar::Set::BlockDefinitionScope.new.block_to_assign(1)
+
+      caller.set_class_variable_with_block(receiver, block)
+      BasicObjectSpecs::InstEval::CVar::Set::BlockDefinitionScope.get_class_variable.should == 1
+    end
+
+    it "does not have access to class variables in the receiver class when called with a String" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Get::ReceiverScope.new
+      caller = BasicObjectSpecs::InstEval::CVar::Get::CallerWithoutCVarScope.new
+      -> { caller.get_class_variable_with_string(receiver) }.should.raise(NameError, /uninitialized class variable @@cvar/)
+    end
+
+    it "does not have access to class variables in the receiver's singleton class when called with a String" do
+      receiver = BasicObjectSpecs::InstEval::CVar::Get::ReceiverWithCVarDefinedInSingletonClass
+      caller = BasicObjectSpecs::InstEval::CVar::Get::CallerWithoutCVarScope.new
+      -> { caller.get_class_variable_with_string(receiver) }.should.raise(NameError, /uninitialized class variable @@cvar/)
+    end
   end
-end
 
   it "raises a TypeError when defining methods on numerics" do
     -> do
       (1.0).instance_eval { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
     -> do
       (1 << 64).instance_eval { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "evaluates procs originating from methods" do
@@ -185,4 +270,58 @@ end
 
     x.should == :value
   end
+
+  it "converts string argument with #to_str method" do
+    source_code = Object.new
+    def source_code.to_str() "1" end
+
+    a = BasicObject.new
+    a.instance_eval(source_code).should == 1
+  end
+
+  it "raises ArgumentError if returned value is not String" do
+    source_code = Object.new
+    def source_code.to_str() :symbol end
+
+    a = BasicObject.new
+    -> { a.instance_eval(source_code) }.should raise_consistent_error(TypeError, /can't convert Object into String/)
+  end
+
+  it "converts filename argument with #to_str method" do
+    filename = Object.new
+    def filename.to_str() "file.rb" end
+
+    err = begin
+            Object.new.instance_eval("raise", filename)
+          rescue => e
+            e
+          end
+    err.backtrace.first.split(":")[0].should == "file.rb"
+  end
+
+  it "raises ArgumentError if returned value is not String" do
+    filename = Object.new
+    def filename.to_str() :symbol end
+
+    -> { Object.new.instance_eval("raise", filename) }.should raise_consistent_error(TypeError, /can't convert Object into String/)
+  end
+
+  it "converts lineno argument with #to_int method" do
+    lineno = Object.new
+    def lineno.to_int() 15 end
+
+    err = begin
+            Object.new.instance_eval("raise", "file.rb", lineno)
+          rescue => e
+            e
+          end
+    err.backtrace.first.split(":")[1].should == "15"
+  end
+
+  it "raises ArgumentError if returned value is not Integer" do
+    lineno = Object.new
+    def lineno.to_int() :symbol end
+
+    -> { Object.new.instance_eval("raise", "file.rb", lineno) }.should raise_consistent_error(TypeError, /can't convert Object into Integer/)
+  end
 end
diff --git a/spec/ruby/core/basicobject/instance_exec_spec.rb b/spec/ruby/core/basicobject/instance_exec_spec.rb
index e25482d58a..cfce9a65ad 100644
--- a/spec/ruby/core/basicobject/instance_exec_spec.rb
+++ b/spec/ruby/core/basicobject/instance_exec_spec.rb
@@ -3,21 +3,21 @@ require_relative 'fixtures/classes'
 
 describe "BasicObject#instance_exec" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:instance_exec)
+    BasicObject.public_instance_methods(false).should.include?(:instance_exec)
   end
 
   it "sets self to the receiver in the context of the passed block" do
     a = BasicObject.new
-    a.instance_exec { self }.equal?(a).should be_true
+    a.instance_exec { self }.equal?(a).should == true
   end
 
   it "passes arguments to the block" do
     a = BasicObject.new
-    a.instance_exec(1) { |b| b }.should equal(1)
+    a.instance_exec(1) { |b| b }.should.equal?(1)
   end
 
   it "raises a LocalJumpError unless given a block" do
-    -> { "hola".instance_exec }.should raise_error(LocalJumpError)
+    -> { "hola".instance_exec }.should.raise(LocalJumpError)
   end
 
   it "has an arity of -1" do
@@ -25,17 +25,23 @@ describe "BasicObject#instance_exec" do
   end
 
   it "accepts arguments with a block" do
-    -> { "hola".instance_exec(4, 5) { |a,b| a + b } }.should_not raise_error
+    -> { "hola".instance_exec(4, 5) { |a,b| a + b } }.should_not.raise
   end
 
   it "doesn't pass self to the block as an argument" do
-    "hola".instance_exec { |o| o }.should be_nil
+    "hola".instance_exec { |o| o }.should == nil
   end
 
   it "passes any arguments to the block" do
     Object.new.instance_exec(1,2) {|one, two| one + two}.should == 3
   end
 
+  describe "with optional argument" do
+    it "does not destructure a single array argument" do
+      Object.new.instance_exec([1, 2, 3]) { |a = 99| a }.should == [1, 2, 3]
+    end
+  end
+
   it "only binds the exec to the receiver" do
     f = Object.new
     f.instance_exec do
@@ -44,7 +50,7 @@ describe "BasicObject#instance_exec" do
       end
     end
     f.foo.should == 1
-    -> { Object.new.foo }.should raise_error(NoMethodError)
+    -> { Object.new.foo }.should.raise(NoMethodError)
   end
 
   # TODO: This should probably be replaced with a "should behave like" that uses
@@ -71,37 +77,37 @@ describe "BasicObject#instance_exec" do
   end
 
   it "sets class variables in the receiver" do
-    BasicObjectSpecs::InstExec.class_variables.should include(:@@count)
+    BasicObjectSpecs::InstExec.class_variables.should.include?(:@@count)
     BasicObjectSpecs::InstExec.send(:class_variable_get, :@@count).should == 2
   end
 
   it "raises a TypeError when defining methods on an immediate" do
     -> do
       1.instance_exec { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
     -> do
       :foo.instance_exec { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
-quarantine! do # Not clean, leaves cvars lying around to break other specs
-  it "scopes class var accesses in the caller when called on a Fixnum" do
-    # Fixnum can take instance vars
-    Fixnum.class_eval "@@__tmp_instance_exec_spec = 1"
-    (defined? @@__tmp_instance_exec_spec).should == nil
+  quarantine! do # Not clean, leaves cvars lying around to break other specs
+    it "scopes class var accesses in the caller when called on an Integer" do
+      # Integer can take instance vars
+      Integer.class_eval "@@__tmp_instance_exec_spec = 1"
+      (defined? @@__tmp_instance_exec_spec).should == nil
 
-    @@__tmp_instance_exec_spec = 2
-    1.instance_exec { @@__tmp_instance_exec_spec }.should == 2
-    Fixnum.__send__(:remove_class_variable, :@@__tmp_instance_exec_spec)
+      @@__tmp_instance_exec_spec = 2
+      1.instance_exec { @@__tmp_instance_exec_spec }.should == 2
+      Integer.__send__(:remove_class_variable, :@@__tmp_instance_exec_spec)
+    end
   end
-end
 
   it "raises a TypeError when defining methods on numerics" do
     -> do
       (1.0).instance_exec { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
     -> do
       (1 << 64).instance_exec { def foo; end }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/basicobject/method_missing_spec.rb b/spec/ruby/core/basicobject/method_missing_spec.rb
index b048780ee8..8785b41b21 100644
--- a/spec/ruby/core/basicobject/method_missing_spec.rb
+++ b/spec/ruby/core/basicobject/method_missing_spec.rb
@@ -1,8 +1,9 @@
+require_relative "../../spec_helper"
 require_relative '../../shared/basicobject/method_missing'
 
 describe "BasicObject#method_missing" do
   it "is a private method" do
-    BasicObject.should have_private_instance_method(:method_missing)
+    BasicObject.private_instance_methods(false).should.include?(:method_missing)
   end
 end
 
diff --git a/spec/ruby/core/basicobject/not_equal_spec.rb b/spec/ruby/core/basicobject/not_equal_spec.rb
index 9329128c43..29b14b0fff 100644
--- a/spec/ruby/core/basicobject/not_equal_spec.rb
+++ b/spec/ruby/core/basicobject/not_equal_spec.rb
@@ -2,24 +2,24 @@ require_relative '../../spec_helper'
 
 describe "BasicObject#!=" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:'!=')
+    BasicObject.public_instance_methods(false).should.include?(:'!=')
   end
 
   it "returns true if other is not identical to self" do
     a = BasicObject.new
     b = BasicObject.new
-    (a != b).should be_true
+    (a != b).should == true
   end
 
   it "returns true if other is an Object" do
     a = BasicObject.new
     b = Object.new
-    (a != b).should be_true
+    (a != b).should == true
   end
 
   it "returns false if other is identical to self" do
     a = BasicObject.new
-    (a != a).should be_false
+    (a != a).should == false
   end
 
   it "dispatches to #==" do
@@ -27,19 +27,19 @@ describe "BasicObject#!=" do
     b = BasicObject.new
     a.should_receive(:==).and_return(true)
 
-    (a != b).should be_false
+    (a != b).should == false
   end
 
   describe "when invoked using Kernel#send" do
     it "returns true if other is not identical to self" do
       a = Object.new
       b = Object.new
-      a.send(:!=, b).should be_true
+      a.send(:!=, b).should == true
     end
 
     it "returns false if other is identical to self" do
       a = Object.new
-      a.send(:!=, a).should be_false
+      a.send(:!=, a).should == false
     end
 
     it "dispatches to #==" do
@@ -47,7 +47,7 @@ describe "BasicObject#!=" do
       b = Object.new
       a.should_receive(:==).and_return(true)
 
-      a.send(:!=, b).should be_false
+      a.send(:!=, b).should == false
     end
   end
 end
diff --git a/spec/ruby/core/basicobject/not_spec.rb b/spec/ruby/core/basicobject/not_spec.rb
index ca4cb6f5ff..a6f58ae6f5 100644
--- a/spec/ruby/core/basicobject/not_spec.rb
+++ b/spec/ruby/core/basicobject/not_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "BasicObject#!" do
   it "is a public instance method" do
-    BasicObject.should have_public_instance_method(:'!')
+    BasicObject.public_instance_methods(false).should.include?(:'!')
   end
 
   it "returns false" do
-    (!BasicObject.new).should be_false
+    (!BasicObject.new).should == false
   end
 end
diff --git a/spec/ruby/core/basicobject/singleton_method_added_spec.rb b/spec/ruby/core/basicobject/singleton_method_added_spec.rb
index 8d256e22db..f39b91768c 100644
--- a/spec/ruby/core/basicobject/singleton_method_added_spec.rb
+++ b/spec/ruby/core/basicobject/singleton_method_added_spec.rb
@@ -7,7 +7,7 @@ describe "BasicObject#singleton_method_added" do
   end
 
   it "is a private method" do
-    BasicObject.should have_private_instance_method(:singleton_method_added)
+    BasicObject.private_instance_methods(false).should.include?(:singleton_method_added)
   end
 
   it "is called when a singleton method is defined on an object" do
@@ -35,7 +35,7 @@ describe "BasicObject#singleton_method_added" do
       end
     end
 
-    ScratchPad.recorded.should_not include(:new_instance_method)
+    ScratchPad.recorded.should_not.include?(:new_instance_method)
   end
 
   it "is called when a singleton method is defined on a module" do
@@ -83,4 +83,65 @@ describe "BasicObject#singleton_method_added" do
     end
     ScratchPad.recorded.should == [:singleton_method_added, :new_method_with_define_method]
   end
+
+  describe "when singleton_method_added is undefined" do
+    it "raises NoMethodError for a metaclass" do
+      class BasicObjectSpecs::NoSingletonMethodAdded
+        class << self
+          undef_method :singleton_method_added
+        end
+
+        -> {
+          def self.foo
+          end
+        }.should.raise(NoMethodError, /undefined method [`']singleton_method_added' for/)
+      end
+    ensure
+      BasicObjectSpecs.send(:remove_const, :NoSingletonMethodAdded)
+    end
+
+    it "raises NoMethodError for a singleton instance" do
+      object = Object.new
+      class << object
+        undef_method :singleton_method_added
+
+        -> {
+          def foo
+          end
+        }.should.raise(NoMethodError, /undefined method [`']singleton_method_added' for #<Object:/)
+
+        -> {
+          define_method(:bar) {}
+        }.should.raise(NoMethodError, /undefined method [`']singleton_method_added' for #<Object:/)
+      end
+
+      -> {
+        object.define_singleton_method(:baz) {}
+      }.should.raise(NoMethodError, /undefined method [`']singleton_method_added' for #<Object:/)
+    end
+
+    it "calls #method_missing" do
+      ScratchPad.record []
+      object = Object.new
+      class << object
+        def method_missing(*args)
+          ScratchPad << args
+        end
+
+        undef_method :singleton_method_added
+
+        def foo
+        end
+
+        define_method(:bar) {}
+      end
+      object.define_singleton_method(:baz) {}
+
+      ScratchPad.recorded.should == [
+        [:singleton_method_added, :foo],
+        [:singleton_method_added, :bar],
+        [:singleton_method_added, :baz],
+      ]
+    end
+  end
 end
diff --git a/spec/ruby/core/basicobject/singleton_method_removed_spec.rb b/spec/ruby/core/basicobject/singleton_method_removed_spec.rb
index 46f9a6894c..1831e3c070 100644
--- a/spec/ruby/core/basicobject/singleton_method_removed_spec.rb
+++ b/spec/ruby/core/basicobject/singleton_method_removed_spec.rb
@@ -6,7 +6,7 @@ describe "BasicObject#singleton_method_removed" do
   end
 
   it "is a private method" do
-    BasicObject.should have_private_instance_method(:singleton_method_removed)
+    BasicObject.private_instance_methods(false).should.include?(:singleton_method_removed)
   end
 
   it "is called when a method is removed on self" do
diff --git a/spec/ruby/core/basicobject/singleton_method_undefined_spec.rb b/spec/ruby/core/basicobject/singleton_method_undefined_spec.rb
index 7d6c7207db..cc47341878 100644
--- a/spec/ruby/core/basicobject/singleton_method_undefined_spec.rb
+++ b/spec/ruby/core/basicobject/singleton_method_undefined_spec.rb
@@ -6,7 +6,7 @@ describe "BasicObject#singleton_method_undefined" do
   end
 
   it "is a private method" do
-    BasicObject.should have_private_instance_method(:singleton_method_undefined)
+    BasicObject.private_instance_methods(false).should.include?(:singleton_method_undefined)
   end
 
   it "is called when a method is removed on self" do
diff --git a/spec/ruby/core/binding/clone_spec.rb b/spec/ruby/core/binding/clone_spec.rb
index ebd40f5377..f1769ac6de 100644
--- a/spec/ruby/core/binding/clone_spec.rb
+++ b/spec/ruby/core/binding/clone_spec.rb
@@ -4,4 +4,10 @@ require_relative 'shared/clone'
 
 describe "Binding#clone" do
   it_behaves_like :binding_clone, :clone
+
+  it "preserves frozen status" do
+    bind = binding.freeze
+    bind.frozen?.should == true
+    bind.clone.frozen?.should == true
+  end
 end
diff --git a/spec/ruby/core/binding/dup_spec.rb b/spec/ruby/core/binding/dup_spec.rb
index 43968213c8..f5f0c72d5d 100644
--- a/spec/ruby/core/binding/dup_spec.rb
+++ b/spec/ruby/core/binding/dup_spec.rb
@@ -4,4 +4,27 @@ require_relative 'shared/clone'
 
 describe "Binding#dup" do
   it_behaves_like :binding_clone, :dup
+
+  it "resets frozen status" do
+    bind = binding.freeze
+    bind.frozen?.should == true
+    bind.dup.frozen?.should == false
+  end
+
+  it "retains original binding variables but the list is distinct" do
+    bind1 = binding
+    eval "a = 1", bind1
+
+    bind2 = bind1.dup
+    eval("a = 2", bind2)
+    eval("a", bind1).should == 2
+    eval("a", bind2).should == 2
+
+    eval("b = 2", bind2)
+    -> { eval("b", bind1) }.should.raise(NameError)
+    eval("b", bind2).should == 2
+
+    bind1.local_variables.sort.should == [:a, :bind1, :bind2]
+    bind2.local_variables.sort.should == [:a, :b, :bind1, :bind2]
+  end
 end
diff --git a/spec/ruby/core/binding/eval_spec.rb b/spec/ruby/core/binding/eval_spec.rb
index fff8c9cf44..f1d8591320 100644
--- a/spec/ruby/core/binding/eval_spec.rb
+++ b/spec/ruby/core/binding/eval_spec.rb
@@ -7,7 +7,7 @@ describe "Binding#eval" do
     bind = obj.get_binding
 
     bind.eval("@secret += square(3)").should == 10
-    bind.eval("a").should be_true
+    bind.eval("a").should == true
 
     bind.eval("class Inside; end")
     bind.eval("Inside.name").should == "BindingSpecs::Demo::Inside"
@@ -23,29 +23,29 @@ describe "Binding#eval" do
     bind2.local_variables.should == []
   end
 
-  it "inherits __LINE__ from the enclosing scope" do
+  it "starts with line 1 if single argument is given" do
     obj = BindingSpecs::Demo.new(1)
     bind = obj.get_binding
-    suppress_warning {bind.eval("__LINE__")}.should == obj.get_line_of_binding
+    bind.eval("__LINE__").should == 1
   end
 
   it "preserves __LINE__ across multiple calls to eval" do
     obj = BindingSpecs::Demo.new(1)
     bind = obj.get_binding
-    suppress_warning {bind.eval("__LINE__")}.should == obj.get_line_of_binding
-    suppress_warning {bind.eval("__LINE__")}.should == obj.get_line_of_binding
+    bind.eval("__LINE__").should == 1
+    bind.eval("__LINE__").should == 1
   end
 
   it "increments __LINE__ on each line of a multiline eval" do
     obj = BindingSpecs::Demo.new(1)
     bind = obj.get_binding
-    suppress_warning {bind.eval("#foo\n__LINE__")}.should == obj.get_line_of_binding + 1
+    bind.eval("#foo\n__LINE__").should == 2
   end
 
-  it "inherits __LINE__ from the enclosing scope even if the Binding is created with #send" do
+  it "starts with line 1 if the Binding is created with #send" do
     obj = BindingSpecs::Demo.new(1)
     bind, line = obj.get_binding_with_send_and_line
-    suppress_warning {bind.eval("__LINE__")}.should == line
+    bind.eval("__LINE__").should == 1
   end
 
   it "starts with a __LINE__ of 1 if a filename is passed" do
@@ -60,10 +60,10 @@ describe "Binding#eval" do
     bind.eval("#foo\n__LINE__", "(test)", 88).should == 89
   end
 
-  it "inherits __FILE__ from the enclosing scope" do
+  it "uses 1 as __LINE__" do
     obj = BindingSpecs::Demo.new(1)
     bind = obj.get_binding
-    suppress_warning {bind.eval("__FILE__")}.should == obj.get_file_of_binding
+    suppress_warning { bind.eval("__LINE__") }.should == 1
   end
 
   it "uses the __FILE__ that is passed in" do
@@ -92,4 +92,14 @@ describe "Binding#eval" do
     bind, meth = obj.get_binding_with_send_and_method
     bind.eval("__method__").should == meth
   end
+
+  it "reflects refinements activated in the binding scope" do
+    bind = BindingSpecs::Refined.refined_binding
+
+    bind.eval("'bar'.foo").should == "foo"
+  end
+
+  it "uses the caller location as default filename" do
+    binding.eval("[__FILE__, __LINE__]").should == ["(eval at #{__FILE__}:#{__LINE__})", 1]
+  end
 end
diff --git a/spec/ruby/core/binding/fixtures/classes.rb b/spec/ruby/core/binding/fixtures/classes.rb
index 43e32cacf6..b5f3ce9008 100644
--- a/spec/ruby/core/binding/fixtures/classes.rb
+++ b/spec/ruby/core/binding/fixtures/classes.rb
@@ -49,4 +49,18 @@ module BindingSpecs
       end
     end
   end
+
+  module AddFooToString
+    refine(String) do
+      def foo
+        "foo"
+      end
+    end
+  end
+  class Refined
+    using AddFooToString
+    def self.refined_binding
+      binding
+    end
+  end
 end
diff --git a/spec/ruby/core/binding/fixtures/irb.rb b/spec/ruby/core/binding/fixtures/irb.rb
deleted file mode 100644
index 5f305f2d5d..0000000000
--- a/spec/ruby/core/binding/fixtures/irb.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-a = 10
-
-binding.irb
diff --git a/spec/ruby/core/binding/fixtures/irbrc b/spec/ruby/core/binding/fixtures/irbrc
deleted file mode 100644
index 2bc12af2f7..0000000000
--- a/spec/ruby/core/binding/fixtures/irbrc
+++ /dev/null
@@ -1 +0,0 @@
-# empty configuration
diff --git a/spec/ruby/core/binding/irb_spec.rb b/spec/ruby/core/binding/irb_spec.rb
deleted file mode 100644
index bd37b419f9..0000000000
--- a/spec/ruby/core/binding/irb_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../spec_helper'
-
-ruby_version_is "2.5" do
-  describe "Binding#irb" do
-    it "creates an IRB session with the binding in scope" do
-      irb_fixture = fixture __FILE__, "irb.rb"
-      irbrc_fixture = fixture __FILE__, "irbrc"
-
-      out = IO.popen([{"IRBRC"=>irbrc_fixture}, *ruby_exe, irb_fixture], "r+") do |pipe|
-        pipe.puts "a ** 2"
-        pipe.puts "exit"
-        pipe.readlines.map(&:chomp)
-      end
-
-      out[-3..-1].should == ["a ** 2", "100", "exit"]
-    end
-  end
-end
diff --git a/spec/ruby/core/binding/local_variable_get_spec.rb b/spec/ruby/core/binding/local_variable_get_spec.rb
index 005670becc..d97100deda 100644
--- a/spec/ruby/core/binding/local_variable_get_spec.rb
+++ b/spec/ruby/core/binding/local_variable_get_spec.rb
@@ -13,7 +13,7 @@ describe "Binding#local_variable_get" do
 
     -> {
       bind.local_variable_get(:no_such_variable)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "reads variables added later to the binding" do
@@ -21,7 +21,7 @@ describe "Binding#local_variable_get" do
 
     -> {
       bind.local_variable_get(:a)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
 
     bind.local_variable_set(:a, 42)
 
@@ -45,12 +45,12 @@ describe "Binding#local_variable_get" do
 
   it "raises a NameError on global access" do
     bind = binding
-    -> { bind.local_variable_get(:$0) }.should raise_error(NameError)
+    -> { bind.local_variable_get(:$0) }.should.raise(NameError)
   end
 
   it "raises a NameError on special variable access" do
     bind = binding
-    -> { bind.local_variable_get(:$~) }.should raise_error(NameError)
-    -> { bind.local_variable_get(:$_) }.should raise_error(NameError)
+    -> { bind.local_variable_get(:$~) }.should.raise(NameError)
+    -> { bind.local_variable_get(:$_) }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/binding/local_variable_set_spec.rb b/spec/ruby/core/binding/local_variable_set_spec.rb
index 1456c6dda1..3e4f407fc3 100644
--- a/spec/ruby/core/binding/local_variable_set_spec.rb
+++ b/spec/ruby/core/binding/local_variable_set_spec.rb
@@ -38,7 +38,7 @@ describe "Binding#local_variable_set" do
     bind = binding
     bind.local_variable_set(:number, 10)
 
-    -> { number }.should raise_error(NameError)
+    -> { number }.should.raise(NameError)
   end
 
   it 'overwrites an existing local variable defined before a Binding' do
@@ -59,13 +59,13 @@ describe "Binding#local_variable_set" do
 
   it "raises a NameError on global access" do
     bind = binding
-    -> { bind.local_variable_set(:$0, "") }.should raise_error(NameError)
+    -> { bind.local_variable_set(:$0, "") }.should.raise(NameError)
   end
 
   it "raises a NameError on special variable access" do
     bind = binding
-    -> { bind.local_variable_set(:$~, "") }.should raise_error(NameError)
-    -> { bind.local_variable_set(:$_, "") }.should raise_error(NameError)
+    -> { bind.local_variable_set(:$~, "") }.should.raise(NameError)
+    -> { bind.local_variable_set(:$_, "") }.should.raise(NameError)
   end
 
 end
diff --git a/spec/ruby/core/binding/local_variables_spec.rb b/spec/ruby/core/binding/local_variables_spec.rb
index 92c817b9a8..0f59681342 100644
--- a/spec/ruby/core/binding/local_variables_spec.rb
+++ b/spec/ruby/core/binding/local_variables_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Binding#local_variables" do
   it "returns an Array" do
-    binding.local_variables.should be_kind_of(Array)
+    binding.local_variables.should.is_a?(Array)
   end
 
   it "includes local variables in the current scope" do
diff --git a/spec/ruby/core/binding/shared/clone.rb b/spec/ruby/core/binding/shared/clone.rb
index 0e934ac1b5..2d854fce96 100644
--- a/spec/ruby/core/binding/shared/clone.rb
+++ b/spec/ruby/core/binding/shared/clone.rb
@@ -31,4 +31,26 @@ describe :binding_clone, shared: true do
       b2.local_variable_defined?(:x).should == false
     end
   end
+
+  ruby_version_is "3.4" do
+    it "copies instance variables" do
+      @b1.instance_variable_set(:@ivar, 1)
+      cl = @b1.send(@method)
+      cl.instance_variables.should == [:@ivar]
+    end
+
+    it "copies the finalizer" do
+      code = <<-'RUBY'
+        obj = binding
+
+        ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized\n" })
+
+        obj.clone
+
+        exit 0
+      RUBY
+
+      ruby_exe(code).lines.sort.should == ["finalized\n", "finalized\n"]
+    end
+  end
 end
diff --git a/spec/ruby/core/binding/source_location_spec.rb b/spec/ruby/core/binding/source_location_spec.rb
index e562bc65c8..d1c8191ea8 100644
--- a/spec/ruby/core/binding/source_location_spec.rb
+++ b/spec/ruby/core/binding/source_location_spec.rb
@@ -1,11 +1,14 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/location'
 
-ruby_version_is "2.6" do
-  describe "Binding#source_location" do
-    it "returns an [file, line] pair" do
-      b = BindingSpecs::LocationMethod::TEST_BINDING
-      b.source_location.should == [BindingSpecs::LocationMethod::FILE_PATH, 4]
-    end
+describe "Binding#source_location" do
+  it "returns an [file, line] pair" do
+    b = BindingSpecs::LocationMethod::TEST_BINDING
+    b.source_location.should == [BindingSpecs::LocationMethod::FILE_PATH, 4]
+  end
+
+  it "works for eval with a given line" do
+    b = eval('binding', nil, "foo", 100)
+    b.source_location.should == ["foo", 100]
   end
 end
diff --git a/spec/ruby/core/builtin_constants/builtin_constants_spec.rb b/spec/ruby/core/builtin_constants/builtin_constants_spec.rb
index a5141c3008..67b3339aa6 100644
--- a/spec/ruby/core/builtin_constants/builtin_constants_spec.rb
+++ b/spec/ruby/core/builtin_constants/builtin_constants_spec.rb
@@ -2,56 +2,148 @@ require_relative '../../spec_helper'
 
 describe "RUBY_VERSION" do
   it "is a String" do
-    RUBY_VERSION.should be_kind_of(String)
+    RUBY_VERSION.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_VERSION.should.frozen?
   end
 end
 
 describe "RUBY_PATCHLEVEL" do
-  it "is a Fixnum" do
-    RUBY_PATCHLEVEL.should be_kind_of(Fixnum)
+  it "is an Integer" do
+    RUBY_PATCHLEVEL.should.is_a?(Integer)
   end
 end
 
 describe "RUBY_COPYRIGHT" do
   it "is a String" do
-    RUBY_COPYRIGHT.should be_kind_of(String)
+    RUBY_COPYRIGHT.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_COPYRIGHT.should.frozen?
   end
 end
 
 describe "RUBY_DESCRIPTION" do
   it "is a String" do
-    RUBY_DESCRIPTION.should be_kind_of(String)
+    RUBY_DESCRIPTION.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_DESCRIPTION.should.frozen?
   end
 end
 
 describe "RUBY_ENGINE" do
   it "is a String" do
-    RUBY_ENGINE.should be_kind_of(String)
+    RUBY_ENGINE.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_ENGINE.should.frozen?
+  end
+end
+
+describe "RUBY_ENGINE_VERSION" do
+  it "is a String" do
+    RUBY_ENGINE_VERSION.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_ENGINE_VERSION.should.frozen?
   end
 end
 
 describe "RUBY_PLATFORM" do
   it "is a String" do
-    RUBY_PLATFORM.should be_kind_of(String)
+    RUBY_PLATFORM.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_PLATFORM.should.frozen?
   end
 end
 
 describe "RUBY_RELEASE_DATE" do
   it "is a String" do
-    RUBY_RELEASE_DATE.should be_kind_of(String)
+    RUBY_RELEASE_DATE.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_RELEASE_DATE.should.frozen?
   end
 end
 
 describe "RUBY_REVISION" do
-  ruby_version_is ""..."2.7" do
-    it "is an Integer" do
-      RUBY_REVISION.should be_kind_of(Fixnum)
+  it "is a String" do
+    RUBY_REVISION.should.is_a?(String)
+  end
+
+  it "is frozen" do
+    RUBY_REVISION.should.frozen?
+  end
+end
+
+ruby_version_is "4.0" do
+  describe "Ruby" do
+    it "is a Module" do
+      Ruby.should.instance_of?(Module)
+    end
+  end
+
+  describe "Ruby::VERSION" do
+    it "is equal to RUBY_VERSION" do
+      Ruby::VERSION.should.equal?(RUBY_VERSION)
+    end
+  end
+
+  describe "RUBY::PATCHLEVEL" do
+    it "is equal to RUBY_PATCHLEVEL" do
+      Ruby::PATCHLEVEL.should.equal?(RUBY_PATCHLEVEL)
+    end
+  end
+
+  describe "Ruby::COPYRIGHT" do
+    it "is equal to RUBY_COPYRIGHT" do
+      Ruby::COPYRIGHT.should.equal?(RUBY_COPYRIGHT)
+    end
+  end
+
+  describe "Ruby::DESCRIPTION" do
+    it "is equal to RUBY_DESCRIPTION" do
+      Ruby::DESCRIPTION.should.equal?(RUBY_DESCRIPTION)
+    end
+  end
+
+  describe "Ruby::ENGINE" do
+    it "is equal to RUBY_ENGINE" do
+      Ruby::ENGINE.should.equal?(RUBY_ENGINE)
+    end
+  end
+
+  describe "Ruby::ENGINE_VERSION" do
+    it "is equal to RUBY_ENGINE_VERSION" do
+      Ruby::ENGINE_VERSION.should.equal?(RUBY_ENGINE_VERSION)
+    end
+  end
+
+  describe "Ruby::PLATFORM" do
+    it "is equal to RUBY_PLATFORM" do
+      Ruby::PLATFORM.should.equal?(RUBY_PLATFORM)
+    end
+  end
+
+  describe "Ruby::RELEASE_DATE" do
+    it "is equal to RUBY_RELEASE_DATE" do
+      Ruby::RELEASE_DATE.should.equal?(RUBY_RELEASE_DATE)
     end
   end
 
-  ruby_version_is "2.7" do
-    it "is a String" do
-      RUBY_REVISION.should be_kind_of(String)
+  describe "Ruby::REVISION" do
+    it "is equal to RUBY_REVISION" do
+      Ruby::REVISION.should.equal?(RUBY_REVISION)
     end
   end
 end
diff --git a/spec/ruby/core/class/allocate_spec.rb b/spec/ruby/core/class/allocate_spec.rb
index c426c38ff9..b8950a678e 100644
--- a/spec/ruby/core/class/allocate_spec.rb
+++ b/spec/ruby/core/class/allocate_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Class#allocate" do
   it "returns an instance of self" do
     klass = Class.new
-    klass.allocate.should be_an_instance_of(klass)
+    klass.allocate.should.instance_of?(klass)
   end
 
   it "returns a fully-formed instance of Module" do
@@ -16,7 +16,7 @@ describe "Class#allocate" do
     klass = Class.allocate
     -> do
       klass.new
-    end.should raise_error(Exception)
+    end.should.raise(Exception)
   end
 
   it "does not call initialize on the new instance" do
@@ -30,12 +30,12 @@ describe "Class#allocate" do
       end
     end
 
-    klass.allocate.initialized?.should == false
+    klass.allocate.should_not.initialized?
   end
 
   it "raises TypeError for #superclass" do
     -> do
       Class.allocate.superclass
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/class/attached_object_spec.rb b/spec/ruby/core/class/attached_object_spec.rb
new file mode 100644
index 0000000000..b75e61ca07
--- /dev/null
+++ b/spec/ruby/core/class/attached_object_spec.rb
@@ -0,0 +1,29 @@
+require_relative '../../spec_helper'
+
+describe "Class#attached_object" do
+  it "returns the object that is attached to a singleton class" do
+    a = Class.new
+
+    a_obj = a.new
+    a_obj.singleton_class.attached_object.should == a_obj
+  end
+
+  it "returns the class object that is attached to a class's singleton class" do
+    a = Class.new
+    singleton_class = (class << a; self; end)
+
+    singleton_class.attached_object.should == a
+  end
+
+  it "raises TypeError if the class is not a singleton class" do
+    a = Class.new
+
+    -> { a.attached_object }.should.raise(TypeError, /is not a singleton class/)
+  end
+
+  it "raises TypeError for special singleton classes" do
+    -> { nil.singleton_class.attached_object }.should.raise(TypeError, /[`']NilClass' is not a singleton class/)
+    -> { true.singleton_class.attached_object }.should.raise(TypeError, /[`']TrueClass' is not a singleton class/)
+    -> { false.singleton_class.attached_object }.should.raise(TypeError, /[`']FalseClass' is not a singleton class/)
+  end
+end
diff --git a/spec/ruby/core/class/dup_spec.rb b/spec/ruby/core/class/dup_spec.rb
index 701fd72e19..17c0171ceb 100644
--- a/spec/ruby/core/class/dup_spec.rb
+++ b/spec/ruby/core/class/dup_spec.rb
@@ -53,12 +53,17 @@ describe "Class#dup" do
 
   it "sets the name from the class to nil if not assigned to a constant" do
     copy = CoreClassSpecs::Record.dup
-    copy.name.should be_nil
+    copy.name.should == nil
   end
 
   it "stores the new name if assigned to a constant" do
     CoreClassSpecs::RecordCopy = CoreClassSpecs::Record.dup
     CoreClassSpecs::RecordCopy.name.should == "CoreClassSpecs::RecordCopy"
+  ensure
+    CoreClassSpecs.send(:remove_const, :RecordCopy)
   end
 
+  it "raises TypeError if called on BasicObject" do
+    -> { BasicObject.dup }.should.raise(TypeError, "can't copy the root class")
+  end
 end
diff --git a/spec/ruby/core/class/inherited_spec.rb b/spec/ruby/core/class/inherited_spec.rb
index 8ef8bb8c35..c9acc740a1 100644
--- a/spec/ruby/core/class/inherited_spec.rb
+++ b/spec/ruby/core/class/inherited_spec.rb
@@ -92,10 +92,27 @@ describe "Class.inherited" do
     end
 
     class << top; private :inherited; end
-    -> { Class.new(top) }.should_not raise_error
+    -> { Class.new(top) }.should_not.raise
 
     class << top; protected :inherited; end
-    -> { Class.new(top) }.should_not raise_error
+    -> { Class.new(top) }.should_not.raise
   end
 
+  it "if the subclass is assigned to a constant, it is all set" do
+    ScratchPad.record []
+
+    parent = Class.new do
+      def self.inherited(subclass)
+        ScratchPad << defined?(self::C)
+        ScratchPad << const_defined?(:C)
+        ScratchPad << constants
+        ScratchPad << const_get(:C)
+        ScratchPad << subclass.name.match?(/\A#<Class:0x\w+>::C\z/)
+      end
+    end
+
+    class parent::C < parent; end
+
+    ScratchPad.recorded.should == ["constant", true, [:C], parent::C, true]
+  end
 end
diff --git a/spec/ruby/core/class/initialize_spec.rb b/spec/ruby/core/class/initialize_spec.rb
index 9678d7b373..ab8f0a157e 100644
--- a/spec/ruby/core/class/initialize_spec.rb
+++ b/spec/ruby/core/class/initialize_spec.rb
@@ -2,24 +2,24 @@ require_relative '../../spec_helper'
 
 describe "Class#initialize" do
   it "is private" do
-    Class.should have_private_method(:initialize)
+    Class.private_methods(false).should.include?(:initialize)
   end
 
   it "raises a TypeError when called on already initialized classes" do
     ->{
-      Fixnum.send :initialize
-    }.should raise_error(TypeError)
+      Integer.send :initialize
+    }.should.raise(TypeError)
 
     ->{
       Object.send :initialize
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   # See [redmine:2601]
   it "raises a TypeError when called on BasicObject" do
     ->{
       BasicObject.send :initialize
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   describe "when given the Class" do
@@ -28,7 +28,7 @@ describe "Class#initialize" do
     end
 
     it "raises a TypeError" do
-      ->{@uninitialized.send(:initialize, Class)}.should raise_error(TypeError)
+      ->{@uninitialized.send(:initialize, Class)}.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/class/new_spec.rb b/spec/ruby/core/class/new_spec.rb
index 8191ce6a37..111e31252e 100644
--- a/spec/ruby/core/class/new_spec.rb
+++ b/spec/ruby/core/class/new_spec.rb
@@ -7,7 +7,7 @@ describe "Class.new with a block given" do
     klass = Class.new do
       self_in_block = self
     end
-    self_in_block.should equal klass
+    self_in_block.should.equal? klass
   end
 
   it "uses the given block as the class' body" do
@@ -70,11 +70,11 @@ describe "Class.new" do
   it "raises a TypeError if passed a metaclass" do
     obj = mock("Class.new metaclass")
     meta = obj.singleton_class
-    -> { Class.new meta }.should raise_error(TypeError)
+    -> { Class.new meta }.should.raise(TypeError)
   end
 
   it "creates a class without a name" do
-    Class.new.name.should be_nil
+    Class.new.name.should == nil
   end
 
   it "creates a class that can be given a name by assigning it to a constant" do
@@ -83,6 +83,8 @@ describe "Class.new" do
     a = Class.new
     MyClass::NestedClass = a
     MyClass::NestedClass.name.should == "MyClass::NestedClass"
+  ensure
+    Object.send(:remove_const, :MyClass)
   end
 
   it "sets the new class' superclass to the given class" do
@@ -95,12 +97,13 @@ describe "Class.new" do
   end
 
   it "raises a TypeError when given a non-Class" do
-    error_msg = /superclass must be a Class/
-    -> { Class.new("")         }.should raise_error(TypeError, error_msg)
-    -> { Class.new(1)          }.should raise_error(TypeError, error_msg)
-    -> { Class.new(:symbol)    }.should raise_error(TypeError, error_msg)
-    -> { Class.new(mock('o'))  }.should raise_error(TypeError, error_msg)
-    -> { Class.new(Module.new) }.should raise_error(TypeError, error_msg)
+    error_msg = /superclass must be a.*Class/
+    -> { Class.new("")              }.should.raise(TypeError, error_msg)
+    -> { Class.new(1)               }.should.raise(TypeError, error_msg)
+    -> { Class.new(:symbol)         }.should.raise(TypeError, error_msg)
+    -> { Class.new(mock('o'))       }.should.raise(TypeError, error_msg)
+    -> { Class.new(Module.new)      }.should.raise(TypeError, error_msg)
+    -> { Class.new(BasicObject.new) }.should.raise(TypeError, error_msg)
   end
 end
 
@@ -126,7 +129,7 @@ describe "Class#new" do
       end
     end
 
-    klass.new.initialized?.should == true
+    klass.new.should.initialized?
     klass.new(1, 2, 3).args.should == [1, 2, 3]
   end
 
@@ -138,8 +141,8 @@ describe "Class#new" do
     end
 
     instance = klass.new
-    instance.should be_kind_of klass
-    instance.class.should equal klass
+    instance.should.is_a? klass
+    instance.class.should.equal? klass
   end
 
   it "passes the block to #initialize" do
diff --git a/spec/ruby/core/class/subclasses_spec.rb b/spec/ruby/core/class/subclasses_spec.rb
new file mode 100644
index 0000000000..c3d7b07e12
--- /dev/null
+++ b/spec/ruby/core/class/subclasses_spec.rb
@@ -0,0 +1,85 @@
+require_relative '../../spec_helper'
+require_relative '../module/fixtures/classes'
+
+describe "Class#subclasses" do
+  it "returns a list of classes directly inheriting from self" do
+    assert_subclasses(ModuleSpecs::Parent, [ModuleSpecs::Child, ModuleSpecs::Child2])
+  end
+
+  it "does not return included modules from the parent" do
+    parent = Class.new
+    child = Class.new(parent)
+    mod = Module.new
+    parent.include(mod)
+
+    assert_subclasses(parent, [child])
+  end
+
+  it "does not return included modules from the child" do
+    parent = Class.new
+    child = Class.new(parent)
+    mod = Module.new
+    parent.include(mod)
+
+    assert_subclasses(parent, [child])
+  end
+
+  it "does not return prepended modules from the parent" do
+    parent = Class.new
+    child = Class.new(parent)
+    mod = Module.new
+    parent.prepend(mod)
+
+    assert_subclasses(parent, [child])
+  end
+
+  it "does not return prepended modules from the child" do
+    parent = Class.new
+    child = Class.new(parent)
+    mod = Module.new
+    child.prepend(mod)
+
+    assert_subclasses(parent, [child])
+  end
+
+  it "does not return singleton classes" do
+    a = Class.new
+
+    a_obj = a.new
+    def a_obj.force_singleton_class
+      42
+    end
+
+    a.subclasses.should_not.include?(a_obj.singleton_class)
+  end
+
+  it "has 1 entry per module or class" do
+    ModuleSpecs::Parent.subclasses.should == ModuleSpecs::Parent.subclasses.uniq
+  end
+
+  it "works when creating subclasses concurrently" do
+    t = 16
+    n = 1000
+    go = false
+    superclass = Class.new
+
+    threads = t.times.map do
+      Thread.new do
+        Thread.pass until go
+        n.times.map do
+          Class.new(superclass)
+        end
+      end
+    end
+
+    go = true
+    classes = threads.map(&:value)
+
+    superclass.subclasses.size.should == t * n
+    superclass.subclasses.each { |c| c.should.is_a?(Class) }
+  end
+
+  def assert_subclasses(mod,subclasses)
+    mod.subclasses.sort_by(&:inspect).should == subclasses.sort_by(&:inspect)
+  end
+end
diff --git a/spec/ruby/core/class/superclass_spec.rb b/spec/ruby/core/class/superclass_spec.rb
index deb5a45336..87d9b20490 100644
--- a/spec/ruby/core/class/superclass_spec.rb
+++ b/spec/ruby/core/class/superclass_spec.rb
@@ -3,12 +3,12 @@ require_relative 'fixtures/classes'
 
 describe "Class#superclass" do
   it "returns the superclass of self" do
-    BasicObject.superclass.should be_nil
+    BasicObject.superclass.should == nil
     Object.superclass.should == BasicObject
     Class.superclass.should == Module
     Class.new.superclass.should == Object
     Class.new(String).superclass.should == String
-    Class.new(Fixnum).superclass.should == Fixnum
+    Class.new(Integer).superclass.should == Integer
   end
 
   # redmine:567
diff --git a/spec/ruby/core/class/to_s_spec.rb b/spec/ruby/core/class/to_s_spec.rb
deleted file mode 100644
index 2055593a03..0000000000
--- a/spec/ruby/core/class/to_s_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-
-describe "Class#to_s" do
-  it 'regular class returns same name as Module#to_s' do
-    String.to_s.should == 'String'
-  end
-
-  describe 'singleton class' do
-    it 'for modules includes module name' do
-      CoreClassSpecs.singleton_class.to_s.should == '#<Class:CoreClassSpecs>'
-    end
-
-    it 'for classes includes class name' do
-      CoreClassSpecs::Record.singleton_class.to_s.should == '#<Class:CoreClassSpecs::Record>'
-    end
-
-    it 'for objects includes class name and object ID' do
-      obj = CoreClassSpecs::Record.new
-      obj.singleton_class.to_s.should =~ /#<Class:#<CoreClassSpecs::Record:0x[0-9a-f]+>>/
-    end
-  end
-end
diff --git a/spec/ruby/core/comparable/clamp_spec.rb b/spec/ruby/core/comparable/clamp_spec.rb
index 6d216220d4..eb1dc1ff98 100644
--- a/spec/ruby/core/comparable/clamp_spec.rb
+++ b/spec/ruby/core/comparable/clamp_spec.rb
@@ -2,20 +2,14 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe 'Comparable#clamp' do
-  it 'raises an Argument error unless given 2 parameters' do
-    c = ComparableSpecs::Weird.new(0)
-    -> { c.clamp(c) }.should raise_error(ArgumentError)
-    -> { c.clamp(c, c, c) }.should raise_error(ArgumentError)
-  end
-
   it 'raises an Argument error unless the 2 parameters are correctly ordered' do
     one = ComparableSpecs::WithOnlyCompareDefined.new(1)
     two = ComparableSpecs::WithOnlyCompareDefined.new(2)
     c = ComparableSpecs::Weird.new(3)
 
-    -> { c.clamp(two, one) }.should raise_error(ArgumentError)
+    -> { c.clamp(two, one) }.should.raise(ArgumentError)
     one.should_receive(:<=>).any_number_of_times.and_return(nil)
-    -> { c.clamp(one, two) }.should raise_error(ArgumentError)
+    -> { c.clamp(one, two) }.should.raise(ArgumentError)
   end
 
   it 'returns self if within the given parameters' do
@@ -24,18 +18,18 @@ describe 'Comparable#clamp' do
     three = ComparableSpecs::WithOnlyCompareDefined.new(3)
     c = ComparableSpecs::Weird.new(2)
 
-    c.clamp(one, two).should equal(c)
-    c.clamp(two, two).should equal(c)
-    c.clamp(one, three).should equal(c)
-    c.clamp(two, three).should equal(c)
+    c.clamp(one, two).should.equal?(c)
+    c.clamp(two, two).should.equal?(c)
+    c.clamp(one, three).should.equal?(c)
+    c.clamp(two, three).should.equal?(c)
   end
 
-  it 'returns the min parameter if smaller than it' do
+  it 'returns the min parameter if less than it' do
     one = ComparableSpecs::WithOnlyCompareDefined.new(1)
     two = ComparableSpecs::WithOnlyCompareDefined.new(2)
     c = ComparableSpecs::Weird.new(0)
 
-    c.clamp(one, two).should equal(one)
+    c.clamp(one, two).should.equal?(one)
   end
 
   it 'returns the max parameter if greater than it' do
@@ -43,6 +37,187 @@ describe 'Comparable#clamp' do
     two = ComparableSpecs::WithOnlyCompareDefined.new(2)
     c = ComparableSpecs::Weird.new(3)
 
-    c.clamp(one, two).should equal(two)
+    c.clamp(one, two).should.equal?(two)
+  end
+
+  context 'max is nil' do
+    it 'returns min if less than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(0)
+      c.clamp(one, nil).should.equal?(one)
+    end
+
+    it 'always returns self if greater than min' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(2)
+      c.clamp(one, nil).should.equal?(c)
+    end
+  end
+
+  context 'min is nil' do
+    it 'returns max if greater than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(2)
+      c.clamp(nil, one).should.equal?(one)
+    end
+
+    it 'always returns self if less than max' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(0)
+      c.clamp(nil, one).should.equal?(c)
+    end
+  end
+
+  it 'always returns self when min is nil and max is nil' do
+    c = ComparableSpecs::Weird.new(1)
+    c.clamp(nil, nil).should.equal?(c)
+  end
+
+  it 'returns self if within the given range parameters' do
+    one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+    two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+    three = ComparableSpecs::WithOnlyCompareDefined.new(3)
+    c = ComparableSpecs::Weird.new(2)
+
+    c.clamp(one..two).should.equal?(c)
+    c.clamp(two..two).should.equal?(c)
+    c.clamp(one..three).should.equal?(c)
+    c.clamp(two..three).should.equal?(c)
+  end
+
+  it 'returns the minimum value of the range parameters if less than it' do
+    one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+    two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+    c = ComparableSpecs::Weird.new(0)
+
+    c.clamp(one..two).should.equal?(one)
+  end
+
+  it 'returns the maximum value of the range parameters if greater than it' do
+    one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+    two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+    c = ComparableSpecs::Weird.new(3)
+
+    c.clamp(one..two).should.equal?(two)
+  end
+
+  it 'raises an Argument error if the range parameter is exclusive' do
+    one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+    two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+    c = ComparableSpecs::Weird.new(3)
+
+    -> { c.clamp(one...two) }.should.raise(ArgumentError)
+  end
+
+  context 'with nil as the max argument' do
+    it 'returns min argument if less than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      zero = ComparableSpecs::WithOnlyCompareDefined.new(0)
+      c = ComparableSpecs::Weird.new(0)
+
+      c.clamp(one, nil).should.equal?(one)
+      c.clamp(zero, nil).should.equal?(c)
+    end
+
+    it 'always returns self if greater than min argument' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(one, nil).should.equal?(c)
+      c.clamp(two, nil).should.equal?(c)
+    end
+  end
+
+  context 'with endless range' do
+    it 'returns minimum value of the range parameters if less than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      zero = ComparableSpecs::WithOnlyCompareDefined.new(0)
+      c = ComparableSpecs::Weird.new(0)
+
+      c.clamp(one..).should.equal?(one)
+      c.clamp(zero..).should.equal?(c)
+    end
+
+    it 'always returns self if greater than minimum value of the range parameters' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      two = ComparableSpecs::WithOnlyCompareDefined.new(2)
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(one..).should.equal?(c)
+      c.clamp(two..).should.equal?(c)
+    end
+
+    it 'works with exclusive range' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(one...).should.equal?(c)
+    end
+  end
+
+  context 'with nil as the min argument' do
+    it 'returns max argument if greater than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(nil, one).should.equal?(one)
+    end
+
+    it 'always returns self if less than max argument' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      zero = ComparableSpecs::WithOnlyCompareDefined.new(0)
+      c = ComparableSpecs::Weird.new(0)
+
+      c.clamp(nil, one).should.equal?(c)
+      c.clamp(nil, zero).should.equal?(c)
+    end
+  end
+
+  context 'with beginless range' do
+    it 'returns maximum value of the range parameters if greater than it' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(..one).should.equal?(one)
+    end
+
+    it 'always returns self if less than maximum value of the range parameters' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      zero = ComparableSpecs::WithOnlyCompareDefined.new(0)
+      c = ComparableSpecs::Weird.new(0)
+
+      c.clamp(..one).should.equal?(c)
+      c.clamp(..zero).should.equal?(c)
+    end
+
+    it 'raises an Argument error if the range parameter is exclusive' do
+      one = ComparableSpecs::WithOnlyCompareDefined.new(1)
+      c = ComparableSpecs::Weird.new(0)
+
+      -> { c.clamp(...one) }.should.raise(ArgumentError)
+    end
+  end
+
+  context 'with nil as the min and the max argument' do
+    it 'always returns self' do
+      c = ComparableSpecs::Weird.new(1)
+
+      c.clamp(nil, nil).should.equal?(c)
+    end
+  end
+
+  context 'with beginless-and-endless range' do
+    it 'always returns self' do
+      c = ComparableSpecs::Weird.new(1)
+
+      c.clamp(nil..nil).should.equal?(c)
+    end
+
+    it 'works with exclusive range' do
+      c = ComparableSpecs::Weird.new(2)
+
+      c.clamp(nil...nil).should.equal?(c)
+    end
   end
 end
diff --git a/spec/ruby/core/comparable/equal_value_spec.rb b/spec/ruby/core/comparable/equal_value_spec.rb
index ddcc03cb41..3af40d1c7e 100644
--- a/spec/ruby/core/comparable/equal_value_spec.rb
+++ b/spec/ruby/core/comparable/equal_value_spec.rb
@@ -39,7 +39,7 @@ describe "Comparable#==" do
     end
 
     it "returns false" do
-      (a == b).should be_false
+      (a == b).should == false
     end
   end
 
@@ -49,7 +49,7 @@ describe "Comparable#==" do
     end
 
     it "raises an ArgumentError" do
-      -> { (a == b) }.should raise_error(ArgumentError)
+      -> { (a == b) }.should.raise(ArgumentError)
     end
   end
 
@@ -60,7 +60,7 @@ describe "Comparable#==" do
       end
 
       it "lets it go through" do
-        -> { (a == b) }.should raise_error(StandardError)
+        -> { (a == b) }.should.raise(StandardError)
       end
     end
 
@@ -71,13 +71,13 @@ describe "Comparable#==" do
       end
 
       it "lets it go through" do
-        -> { (a == b) }.should raise_error(TypeError)
+        -> { (a == b) }.should.raise(TypeError)
       end
     end
 
     it "lets it go through if it is not a StandardError" do
       a.should_receive(:<=>).once.and_raise(Exception)
-      -> { (a == b) }.should raise_error(Exception)
+      -> { (a == b) }.should.raise(Exception)
     end
   end
 
diff --git a/spec/ruby/core/comparable/fixtures/classes.rb b/spec/ruby/core/comparable/fixtures/classes.rb
index 4239a47d2f..2bdabbf014 100644
--- a/spec/ruby/core/comparable/fixtures/classes.rb
+++ b/spec/ruby/core/comparable/fixtures/classes.rb
@@ -7,6 +7,7 @@ module ComparableSpecs
     end
 
     def <=>(other)
+      return nil if other.nil?
       self.value <=> other.value
     end
   end
diff --git a/spec/ruby/core/comparable/gt_spec.rb b/spec/ruby/core/comparable/gt_spec.rb
index 150e653dc7..cebb5464ad 100644
--- a/spec/ruby/core/comparable/gt_spec.rb
+++ b/spec/ruby/core/comparable/gt_spec.rb
@@ -38,6 +38,6 @@ describe "Comparable#>" do
     b = ComparableSpecs::Weird.new(20)
 
     a.should_receive(:<=>).any_number_of_times.and_return(nil)
-    -> { (a > b) }.should raise_error(ArgumentError)
+    -> { (a > b) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/comparable/gte_spec.rb b/spec/ruby/core/comparable/gte_spec.rb
index 328f58c66c..16da81b3ea 100644
--- a/spec/ruby/core/comparable/gte_spec.rb
+++ b/spec/ruby/core/comparable/gte_spec.rb
@@ -42,6 +42,6 @@ describe "Comparable#>=" do
     b = ComparableSpecs::Weird.new(20)
 
     a.should_receive(:<=>).any_number_of_times.and_return(nil)
-    -> { (a >= b) }.should raise_error(ArgumentError)
+    -> { (a >= b) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/comparable/lt_spec.rb b/spec/ruby/core/comparable/lt_spec.rb
index 4db92719e2..175646d0d7 100644
--- a/spec/ruby/core/comparable/lt_spec.rb
+++ b/spec/ruby/core/comparable/lt_spec.rb
@@ -38,6 +38,12 @@ describe "Comparable#<" do
     b = ComparableSpecs::Weird.new(20)
 
     a.should_receive(:<=>).any_number_of_times.and_return(nil)
-    -> { (a < b) }.should raise_error(ArgumentError)
+    -> { (a < b) }.should.raise(ArgumentError)
+  end
+
+  it "raises an argument error with a message containing the value" do
+    -> { ("foo" < 7) }.should.raise(ArgumentError) { |e|
+      e.message.should.include? "String with 7 failed"
+    }
   end
 end
diff --git a/spec/ruby/core/comparable/lte_spec.rb b/spec/ruby/core/comparable/lte_spec.rb
index b5cb9cc4e7..8cbbd5ebb4 100644
--- a/spec/ruby/core/comparable/lte_spec.rb
+++ b/spec/ruby/core/comparable/lte_spec.rb
@@ -41,6 +41,6 @@ describe "Comparable#<=" do
     b = ComparableSpecs::Weird.new(20)
 
     a.should_receive(:<=>).any_number_of_times.and_return(nil)
-    -> { (a <= b) }.should raise_error(ArgumentError)
+    -> { (a <= b) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/complex/abs_spec.rb b/spec/ruby/core/complex/abs_spec.rb
index 43912c517f..ed5aebb11d 100644
--- a/spec/ruby/core/complex/abs_spec.rb
+++ b/spec/ruby/core/complex/abs_spec.rb
@@ -1,6 +1,12 @@
 require_relative '../../spec_helper'
-require_relative 'shared/abs'
 
 describe "Complex#abs" do
-  it_behaves_like :complex_abs, :abs
+  it "returns the modulus: |a + bi| = sqrt((a ^ 2) + (b ^ 2))" do
+    Complex(0, 0).abs.should == 0
+    Complex(3, 4).abs.should == 5 # well-known integer case
+    Complex(-3, 4).abs.should == 5
+    Complex(1, -1).abs.should be_close(Math.sqrt(2), TOLERANCE)
+    Complex(6.5, 0).abs.should be_close(6.5, TOLERANCE)
+    Complex(0, -7.2).abs.should be_close(7.2, TOLERANCE)
+  end
 end
diff --git a/spec/ruby/core/complex/angle_spec.rb b/spec/ruby/core/complex/angle_spec.rb
index 4aa176956f..7551214d2b 100644
--- a/spec/ruby/core/complex/angle_spec.rb
+++ b/spec/ruby/core/complex/angle_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/arg'
 
 describe "Complex#angle" do
-  it_behaves_like :complex_arg, :angle
+  it "is an alias of Complex#arg" do
+    Complex.instance_method(:angle).should == Complex.instance_method(:arg)
+  end
 end
diff --git a/spec/ruby/core/complex/arg_spec.rb b/spec/ruby/core/complex/arg_spec.rb
index 009f19429f..dd64102d77 100644
--- a/spec/ruby/core/complex/arg_spec.rb
+++ b/spec/ruby/core/complex/arg_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
-require_relative 'shared/arg'
 
 describe "Complex#arg" do
-  it_behaves_like :complex_arg, :arg
+  it "returns the argument -- i.e., the angle from (1, 0) in the complex plane" do
+    two_pi = 2 * Math::PI
+    (Complex(1, 0).arg % two_pi).should be_close(0, TOLERANCE)
+    (Complex(0, 2).arg % two_pi).should be_close(Math::PI * 0.5, TOLERANCE)
+    (Complex(-100, 0).arg % two_pi).should be_close(Math::PI, TOLERANCE)
+    (Complex(0, -75.3).arg % two_pi).should be_close(Math::PI * 1.5, TOLERANCE)
+  end
 end
diff --git a/spec/ruby/core/complex/coerce_spec.rb b/spec/ruby/core/complex/coerce_spec.rb
index a30a6c1d5f..d4ea85a713 100644
--- a/spec/ruby/core/complex/coerce_spec.rb
+++ b/spec/ruby/core/complex/coerce_spec.rb
@@ -8,37 +8,37 @@ describe "Complex#coerce" do
   it "returns an array containing other and self as Complex when other is an Integer" do
     result = @one.coerce(2)
     result.should == [2, 1]
-    result.first.should be_kind_of(Complex)
-    result.last.should be_kind_of(Complex)
+    result.first.should.is_a?(Complex)
+    result.last.should.is_a?(Complex)
   end
 
   it "returns an array containing other and self as Complex when other is a Float" do
     result = @one.coerce(20.5)
     result.should == [20.5, 1]
-    result.first.should be_kind_of(Complex)
-    result.last.should be_kind_of(Complex)
+    result.first.should.is_a?(Complex)
+    result.last.should.is_a?(Complex)
   end
 
   it "returns an array containing other and self as Complex when other is a Bignum" do
     result = @one.coerce(4294967296)
     result.should == [4294967296, 1]
-    result.first.should be_kind_of(Complex)
-    result.last.should be_kind_of(Complex)
+    result.first.should.is_a?(Complex)
+    result.last.should.is_a?(Complex)
   end
 
   it "returns an array containing other and self as Complex when other is a Rational" do
     result = @one.coerce(Rational(5,6))
     result.should == [Rational(5,6), 1]
-    result.first.should be_kind_of(Complex)
-    result.last.should be_kind_of(Complex)
+    result.first.should.is_a?(Complex)
+    result.last.should.is_a?(Complex)
   end
 
   it "returns an array containing other and self when other is a Complex" do
     other = Complex(2)
     result = @one.coerce(other)
     result.should == [other, @one]
-    result.first.should equal(other)
-    result.last.should equal(@one)
+    result.first.should.equal?(other)
+    result.last.should.equal?(@one)
   end
 
   it "returns an array containing other as Complex and self when other is a Numeric which responds to #real? with true" do
@@ -46,25 +46,25 @@ describe "Complex#coerce" do
     other.should_receive(:real?).any_number_of_times.and_return(true)
     result = @one.coerce(other)
     result.should == [other, @one]
-    result.first.should eql(Complex(other))
-    result.last.should equal(@one)
+    result.first.should.eql?(Complex(other))
+    result.last.should.equal?(@one)
   end
 
   it "raises TypeError when other is a Numeric which responds to #real? with false" do
     other = mock_numeric('other')
     other.should_receive(:real?).any_number_of_times.and_return(false)
-    -> { @one.coerce(other) }.should raise_error(TypeError)
+    -> { @one.coerce(other) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when other is a String" do
-    -> { @one.coerce("20") }.should raise_error(TypeError)
+    -> { @one.coerce("20") }.should.raise(TypeError)
   end
 
   it "raises a TypeError when other is nil" do
-    -> { @one.coerce(nil) }.should raise_error(TypeError)
+    -> { @one.coerce(nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when other is false" do
-    -> { @one.coerce(false) }.should raise_error(TypeError)
+    -> { @one.coerce(false) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/complex/comparison_spec.rb b/spec/ruby/core/complex/comparison_spec.rb
new file mode 100644
index 0000000000..3115f4e205
--- /dev/null
+++ b/spec/ruby/core/complex/comparison_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+
+describe "Complex#<=>" do
+  it "returns nil if either self or argument has imaginary part" do
+    (Complex(5, 1) <=> Complex(2)).should == nil
+    (Complex(1) <=> Complex(2, 1)).should == nil
+    (5 <=> Complex(2, 1)).should == nil
+  end
+
+  it "returns nil if argument is not numeric" do
+    (Complex(5, 1) <=> "cmp").should == nil
+    (Complex(1) <=> "cmp").should == nil
+    (Complex(1) <=> Object.new).should == nil
+  end
+
+  it "returns 0, 1, or -1 if self and argument do not have imaginary part" do
+    (Complex(5) <=> Complex(2)).should == 1
+    (Complex(2) <=> Complex(3)).should == -1
+    (Complex(2) <=> Complex(2)).should == 0
+
+    (Complex(5) <=> 2).should == 1
+    (Complex(2) <=> 3).should == -1
+    (Complex(2) <=> 2).should == 0
+  end
+end
diff --git a/spec/ruby/core/complex/conj_spec.rb b/spec/ruby/core/complex/conj_spec.rb
index 5e3bc1acb8..063c85faec 100644
--- a/spec/ruby/core/complex/conj_spec.rb
+++ b/spec/ruby/core/complex/conj_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/conjugate'
 
 describe "Complex#conj" do
-  it_behaves_like :complex_conjugate, :conj
+  it "is an alias of Complex#conjugate" do
+    Complex.instance_method(:conj).should == Complex.instance_method(:conjugate)
+  end
 end
diff --git a/spec/ruby/core/complex/conjugate_spec.rb b/spec/ruby/core/complex/conjugate_spec.rb
index f658bab4da..256fe4b3be 100644
--- a/spec/ruby/core/complex/conjugate_spec.rb
+++ b/spec/ruby/core/complex/conjugate_spec.rb
@@ -1,6 +1,10 @@
 require_relative '../../spec_helper'
-require_relative 'shared/conjugate'
 
 describe "Complex#conjugate" do
-  it_behaves_like :complex_conjugate, :conjugate
+  it "returns the complex conjugate: conj a + bi = a - bi" do
+    Complex(3, 5).conjugate.should == Complex(3, -5)
+    Complex(3, -5).conjugate.should == Complex(3, 5)
+    Complex(-3.0, 5.2).conjugate.should be_close(Complex(-3.0, -5.2), TOLERANCE)
+    Complex(3.0, -5.2).conjugate.should be_close(Complex(3.0, 5.2), TOLERANCE)
+  end
 end
diff --git a/spec/ruby/core/complex/constants_spec.rb b/spec/ruby/core/complex/constants_spec.rb
index 50303de16c..200e97731a 100644
--- a/spec/ruby/core/complex/constants_spec.rb
+++ b/spec/ruby/core/complex/constants_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "Complex::I" do
   it "is Complex(0, 1)" do
-    Complex::I.should eql(Complex(0, 1))
+    Complex::I.should.eql?(Complex(0, 1))
   end
 end
diff --git a/spec/ruby/core/complex/divide_spec.rb b/spec/ruby/core/complex/divide_spec.rb
index bebf862312..d5b4aa3885 100644
--- a/spec/ruby/core/complex/divide_spec.rb
+++ b/spec/ruby/core/complex/divide_spec.rb
@@ -1,6 +1,84 @@
 require_relative '../../spec_helper'
-require_relative 'shared/divide'
 
 describe "Complex#/" do
-  it_behaves_like :complex_divide, :/
+  describe "with Complex" do
+    it "divides according to the usual rule for complex numbers" do
+      a = Complex((1 * 10) - (2 * 20), (1 * 20) + (2 * 10))
+      b = Complex(1, 2)
+      (a / b).should == Complex(10, 20)
+
+      c = Complex((1.5 * 100.2) - (2.1 * -30.3), (1.5 * -30.3) + (2.1 * 100.2))
+      d = Complex(1.5, 2.1)
+      # remember the floating-point arithmetic
+      (c / d).should be_close(Complex(100.2, -30.3), TOLERANCE)
+    end
+  end
+
+  describe "with Fixnum" do
+    it "divides both parts of the Complex number" do
+      (Complex(20, 40) / 2).should == Complex(10, 20)
+      (Complex(30, 30) / 10).should == Complex(3, 3)
+    end
+
+    it "raises a ZeroDivisionError when given zero" do
+      -> { Complex(20, 40) / 0 }.should.raise(ZeroDivisionError)
+    end
+
+    it "produces Rational parts" do
+      (Complex(5, 9) / 2).should.eql?(Complex(Rational(5,2), Rational(9,2)))
+    end
+  end
+
+  describe "with Bignum" do
+    it "divides both parts of the Complex number" do
+      (Complex(20, 40) / 2).should == Complex(10, 20)
+      (Complex(15, 16) / 2.0).should be_close(Complex(7.5, 8), TOLERANCE)
+    end
+  end
+
+  describe "with Float" do
+    it "divides both parts of the Complex number" do
+      (Complex(3, 9) / 1.5).should == Complex(2, 6)
+      (Complex(15, 16) / 2.0).should be_close(Complex(7.5, 8), TOLERANCE)
+    end
+
+    it "returns Complex(Infinity, Infinity) when given zero" do
+      (Complex(20, 40) / 0.0).real.infinite?.should == 1
+      (Complex(20, 40) / 0.0).imag.infinite?.should == 1
+      (Complex(-20, 40) / 0.0).real.infinite?.should == -1
+      (Complex(-20, 40) / 0.0).imag.infinite?.should == 1
+    end
+  end
+
+  describe "with Object" do
+    it "tries to coerce self into other" do
+      value = Complex(3, 9)
+
+      obj = mock("Object")
+      obj.should_receive(:coerce).with(value).and_return([4, 2])
+      (value / obj).should == 2
+    end
+  end
+
+  describe "with a Numeric which responds to #real? with true" do
+    it "returns Complex(real.quo(other), imag.quo(other))" do
+      other = mock_numeric('other')
+      real = mock_numeric('real')
+      imag = mock_numeric('imag')
+      other.should_receive(:real?).and_return(true)
+      real.should_receive(:quo).with(other).and_return(1)
+      imag.should_receive(:quo).with(other).and_return(2)
+      (Complex(real, imag) / other).should == Complex(1, 2)
+    end
+  end
+
+  describe "with a Numeric which responds to #real? with false" do
+    it "coerces the passed argument to Complex and divides the resulting elements" do
+      complex = Complex(3, 0)
+      other = mock_numeric('other')
+      other.should_receive(:real?).any_number_of_times.and_return(false)
+      other.should_receive(:coerce).with(complex).and_return([5, 2])
+      (complex / other).should.eql?(Rational(5, 2))
+    end
+  end
 end
diff --git a/spec/ruby/core/complex/eql_spec.rb b/spec/ruby/core/complex/eql_spec.rb
index 9194efc074..2082a22feb 100644
--- a/spec/ruby/core/complex/eql_spec.rb
+++ b/spec/ruby/core/complex/eql_spec.rb
@@ -2,23 +2,23 @@ require_relative '../../spec_helper'
 
 describe "Complex#eql?" do
   it "returns false if other is not Complex" do
-    Complex(1).eql?(1).should be_false
+    Complex(1).eql?(1).should == false
   end
 
   it "returns true when the respective parts are of the same classes and self == other" do
-    Complex(1, 2).eql?(Complex(1, 2)).should be_true
+    Complex(1, 2).eql?(Complex(1, 2)).should == true
   end
 
   it "returns false when the real parts are of different classes" do
-    Complex(1).eql?(Complex(1.0)).should be_false
+    Complex(1).eql?(Complex(1.0)).should == false
   end
 
   it "returns false when the imaginary parts are of different classes" do
-    Complex(1, 2).eql?(Complex(1, 2.0)).should be_false
+    Complex(1, 2).eql?(Complex(1, 2.0)).should == false
   end
 
   it "returns false when self == other is false" do
-    Complex(1, 2).eql?(Complex(2, 3)).should be_false
+    Complex(1, 2).eql?(Complex(2, 3)).should == false
   end
 
   it "does NOT send #eql? to real or imaginary parts" do
@@ -26,6 +26,6 @@ describe "Complex#eql?" do
     imag = mock_numeric('imag')
     real.should_not_receive(:eql?)
     imag.should_not_receive(:eql?)
-    Complex(real, imag).eql?(Complex(real, imag)).should be_true
+    Complex(real, imag).eql?(Complex(real, imag)).should == true
   end
 end
diff --git a/spec/ruby/core/complex/equal_value_spec.rb b/spec/ruby/core/complex/equal_value_spec.rb
index b1e4f9cfcd..b3562ff3fb 100644
--- a/spec/ruby/core/complex/equal_value_spec.rb
+++ b/spec/ruby/core/complex/equal_value_spec.rb
@@ -53,14 +53,14 @@ describe "Complex#==" do
   end
 
   describe "with Object" do
-    # Fixnum#==, Float#== and Bignum#== only return booleans - Bug?
+    # Integer#== and Float#== only return booleans - Bug?
     it "calls other#== with self" do
       value = Complex(3, 0)
 
       obj = mock("Object")
       obj.should_receive(:==).with(value).and_return(:expected)
 
-      (value == obj).should_not be_false
+      (value == obj).should_not == false
     end
   end
 
@@ -73,11 +73,11 @@ describe "Complex#==" do
     it "returns real == other when the imaginary part is zero" do
       real = mock_numeric('real')
       real.should_receive(:==).with(@other).and_return(true)
-      (Complex(real, 0) == @other).should be_true
+      (Complex(real, 0) == @other).should == true
     end
 
-    it "returns false when when the imaginary part is not zero" do
-      (Complex(3, 1) == @other).should be_false
+    it "returns false when the imaginary part is not zero" do
+      (Complex(3, 1) == @other).should == false
     end
   end
 
@@ -87,7 +87,7 @@ describe "Complex#==" do
       other = mock_numeric('other')
       other.should_receive(:real?).any_number_of_times.and_return(false)
       other.should_receive(:==).with(complex).and_return(true)
-      (complex == other).should be_true
+      (complex == other).should == true
     end
   end
 end
diff --git a/spec/ruby/core/complex/exponent_spec.rb b/spec/ruby/core/complex/exponent_spec.rb
index bf07c90038..d0db0a40c2 100644
--- a/spec/ruby/core/complex/exponent_spec.rb
+++ b/spec/ruby/core/complex/exponent_spec.rb
@@ -1,15 +1,15 @@
 require_relative '../../spec_helper'
 
 describe "Complex#**" do
-  describe "with Fixnum 0" do
+  describe "with Integer 0" do
     it "returns Complex(1)" do
-      (Complex(3, 4) ** 0).should eql(Complex(1))
+      (Complex(3, 4) ** 0).should.eql?(Complex(1))
     end
   end
 
   describe "with Float 0.0" do
     it "returns Complex(1.0, 0.0)" do
-      (Complex(3, 4) ** 0.0).should eql(Complex(1.0, 0.0))
+      (Complex(3, 4) ** 0.0).should.eql?(Complex(1.0, 0.0))
     end
   end
 
diff --git a/spec/ruby/core/complex/fdiv_spec.rb b/spec/ruby/core/complex/fdiv_spec.rb
index 68f7d1b309..fdcbc6a95d 100644
--- a/spec/ruby/core/complex/fdiv_spec.rb
+++ b/spec/ruby/core/complex/fdiv_spec.rb
@@ -2,44 +2,44 @@ require_relative '../../spec_helper'
 
 describe "Complex#fdiv" do
   it "accepts a numeric argument" do
-    -> { Complex(20).fdiv(2) }.should_not raise_error(TypeError)
-    -> { Complex(20).fdiv(2.0) }.should_not raise_error(TypeError)
-    -> { Complex(20).fdiv(bignum_value) }.should_not raise_error(TypeError)
+    -> { Complex(20).fdiv(2) }.should_not.raise(TypeError)
+    -> { Complex(20).fdiv(2.0) }.should_not.raise(TypeError)
+    -> { Complex(20).fdiv(bignum_value) }.should_not.raise(TypeError)
   end
 
   it "accepts a negative numeric argument" do
-    -> { Complex(20).fdiv(-2) }.should_not raise_error(TypeError)
-    -> { Complex(20).fdiv(-2.0) }.should_not raise_error(TypeError)
-    -> { Complex(20).fdiv(-bignum_value) }.should_not raise_error(TypeError)
+    -> { Complex(20).fdiv(-2) }.should_not.raise(TypeError)
+    -> { Complex(20).fdiv(-2.0) }.should_not.raise(TypeError)
+    -> { Complex(20).fdiv(-bignum_value) }.should_not.raise(TypeError)
   end
 
   it "raises a TypeError if passed a non-numeric argument" do
-    -> { Complex(20).fdiv([]) }.should raise_error(TypeError)
-    -> { Complex(20).fdiv(:sym) }.should raise_error(TypeError)
-    -> { Complex(20).fdiv('s') }.should raise_error(TypeError)
+    -> { Complex(20).fdiv([]) }.should.raise(TypeError)
+    -> { Complex(20).fdiv(:sym) }.should.raise(TypeError)
+    -> { Complex(20).fdiv('s') }.should.raise(TypeError)
   end
 
   it "sets the real part to NaN if self's real part is NaN" do
-    Complex(nan_value).fdiv(2).real.nan?.should be_true
+    Complex(nan_value).fdiv(2).real.nan?.should == true
   end
 
   it "sets the imaginary part to NaN if self's imaginary part is NaN" do
-    Complex(2, nan_value).fdiv(2).imag.nan?.should be_true
+    Complex(2, nan_value).fdiv(2).imag.nan?.should == true
   end
 
   it "sets the real and imaginary part to NaN if self's real and imaginary parts are NaN" do
-    Complex(nan_value, nan_value).fdiv(2).imag.nan?.should be_true
-    Complex(nan_value, nan_value).fdiv(2).real.nan?.should be_true
+    Complex(nan_value, nan_value).fdiv(2).imag.nan?.should == true
+    Complex(nan_value, nan_value).fdiv(2).real.nan?.should == true
   end
 
   it "sets the real and imaginary part to NaN if self's real part and the argument are both NaN" do
-    Complex(nan_value, 2).fdiv(nan_value).imag.nan?.should be_true
-    Complex(nan_value, 2).fdiv(nan_value).real.nan?.should be_true
+    Complex(nan_value, 2).fdiv(nan_value).imag.nan?.should == true
+    Complex(nan_value, 2).fdiv(nan_value).real.nan?.should == true
   end
 
   it "sets the real and imaginary part to NaN if self's real part, self's imaginary part, and the argument are NaN" do
-    Complex(nan_value, nan_value).fdiv(nan_value).imag.nan?.should be_true
-    Complex(nan_value, nan_value).fdiv(nan_value).real.nan?.should be_true
+    Complex(nan_value, nan_value).fdiv(nan_value).imag.nan?.should == true
+    Complex(nan_value, nan_value).fdiv(nan_value).real.nan?.should == true
   end
 
   it "sets the real part to Infinity if self's real part is Infinity" do
@@ -58,8 +58,8 @@ describe "Complex#fdiv" do
   end
 
   it "sets the real part to NaN and the imaginary part to NaN if self's imaginary part, self's real part, and the argument are Infinity" do
-    Complex(infinity_value, infinity_value).fdiv(infinity_value).real.nan?.should be_true
-    Complex(infinity_value, infinity_value).fdiv(infinity_value).imag.nan?.should be_true
+    Complex(infinity_value, infinity_value).fdiv(infinity_value).real.nan?.should == true
+    Complex(infinity_value, infinity_value).fdiv(infinity_value).imag.nan?.should == true
   end
 end
 
@@ -71,7 +71,7 @@ describe "Complex#fdiv with no imaginary part" do
   it "returns a Complex number" do
     @numbers.each do |real|
       @numbers.each do |other|
-        Complex(real).fdiv(other).should be_an_instance_of(Complex)
+        Complex(real).fdiv(other).should.instance_of?(Complex)
       end
     end
   end
@@ -103,7 +103,7 @@ describe "Complex#fdiv with an imaginary part" do
       @numbers.each_with_index do |other,idx|
         Complex(
           real,@numbers[idx == 0 ? -1 : idx-1]
-        ).fdiv(other).should be_an_instance_of(Complex)
+        ).fdiv(other).should.instance_of?(Complex)
       end
     end
   end
diff --git a/spec/ruby/core/complex/finite_spec.rb b/spec/ruby/core/complex/finite_spec.rb
index 718848390c..7d9f82404e 100644
--- a/spec/ruby/core/complex/finite_spec.rb
+++ b/spec/ruby/core/complex/finite_spec.rb
@@ -2,31 +2,31 @@ require_relative '../../spec_helper'
 
 describe "Complex#finite?" do
   it "returns true if magnitude is finite" do
-    (1+1i).finite?.should == true
+    (1+1i).should.finite?
   end
 
   it "returns false for positive infinity" do
     value = Complex(Float::INFINITY, 42)
-    value.finite?.should == false
+    value.should_not.finite?
   end
 
   it "returns false for positive complex with infinite imaginary" do
     value = Complex(1, Float::INFINITY)
-    value.finite?.should == false
+    value.should_not.finite?
   end
 
   it "returns false for negative infinity" do
     value = -Complex(Float::INFINITY, 42)
-    value.finite?.should == false
+    value.should_not.finite?
   end
 
   it "returns false for negative complex with infinite imaginary" do
     value = -Complex(1, Float::INFINITY)
-    value.finite?.should == false
+    value.should_not.finite?
   end
 
   it "returns false for NaN" do
     value = Complex(Float::NAN, Float::NAN)
-    value.finite?.should == false
+    value.should_not.finite?
   end
 end
diff --git a/spec/ruby/core/complex/imag_spec.rb b/spec/ruby/core/complex/imag_spec.rb
index 2bafd1ab54..225f168e78 100644
--- a/spec/ruby/core/complex/imag_spec.rb
+++ b/spec/ruby/core/complex/imag_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/image'
 
 describe "Complex#imag" do
-  it_behaves_like :complex_image, :imag
+  it "is an alias of Complex#imaginary" do
+    Complex.instance_method(:imag).should == Complex.instance_method(:imaginary)
+  end
 end
diff --git a/spec/ruby/core/complex/imaginary_spec.rb b/spec/ruby/core/complex/imaginary_spec.rb
index a8a1bfea90..ac9284e934 100644
--- a/spec/ruby/core/complex/imaginary_spec.rb
+++ b/spec/ruby/core/complex/imaginary_spec.rb
@@ -1,6 +1,10 @@
 require_relative '../../spec_helper'
-require_relative 'shared/image'
 
 describe "Complex#imaginary" do
-  it_behaves_like :complex_image, :imaginary
+  it "returns the imaginary part of self" do
+    Complex(1, 0).imaginary.should == 0
+    Complex(2, 1).imaginary.should == 1
+    Complex(6.7, 8.9).imaginary.should == 8.9
+    Complex(1, bignum_value).imaginary.should == bignum_value
+  end
 end
diff --git a/spec/ruby/core/complex/inspect_spec.rb b/spec/ruby/core/complex/inspect_spec.rb
index 71aabde5be..045be94b22 100644
--- a/spec/ruby/core/complex/inspect_spec.rb
+++ b/spec/ruby/core/complex/inspect_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative '../numeric/fixtures/classes'
 
 describe "Complex#inspect" do
   it "returns (${real}+${image}i) for positive imaginary parts" do
@@ -13,4 +14,24 @@ describe "Complex#inspect" do
     Complex(-1, -4).inspect.should == "(-1-4i)"
     Complex(-7, -6.7).inspect.should == "(-7-6.7i)"
   end
+
+  it "calls #inspect on real and imaginary" do
+    real = NumericSpecs::Subclass.new
+    # + because of https://bugs.ruby-lang.org/issues/20337
+    real.should_receive(:inspect).and_return(+"1")
+    imaginary = NumericSpecs::Subclass.new
+    imaginary.should_receive(:inspect).and_return("2")
+    imaginary.should_receive(:<).any_number_of_times.and_return(false)
+    Complex(real, imaginary).inspect.should == "(1+2i)"
+  end
+
+  it "adds an `*' before the `i' if the last character of the imaginary part is not numeric" do
+    real = NumericSpecs::Subclass.new
+    # + because of https://bugs.ruby-lang.org/issues/20337
+    real.should_receive(:inspect).and_return(+"(1)")
+    imaginary = NumericSpecs::Subclass.new
+    imaginary.should_receive(:inspect).and_return("(2)")
+    imaginary.should_receive(:<).any_number_of_times.and_return(false)
+    Complex(real, imaginary).inspect.should == "((1)+(2)*i)"
+  end
 end
diff --git a/spec/ruby/core/complex/integer_spec.rb b/spec/ruby/core/complex/integer_spec.rb
index 0957accb70..559bfbccfd 100644
--- a/spec/ruby/core/complex/integer_spec.rb
+++ b/spec/ruby/core/complex/integer_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Complex#integer?" do
   it "returns false for a Complex with no imaginary part" do
-    Complex(20).integer?.should be_false
+    Complex(20).integer?.should == false
   end
 
   it "returns false for a Complex with an imaginary part" do
-    Complex(20,3).integer?.should be_false
+    Complex(20,3).integer?.should == false
   end
 end
diff --git a/spec/ruby/core/complex/magnitude_spec.rb b/spec/ruby/core/complex/magnitude_spec.rb
index 86f3b29868..6341b4eec8 100644
--- a/spec/ruby/core/complex/magnitude_spec.rb
+++ b/spec/ruby/core/complex/magnitude_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/abs'
 
 describe "Complex#magnitude" do
-  it_behaves_like :complex_abs, :magnitude
+  it "is an alias of Complex#abs" do
+    Complex.instance_method(:magnitude).should == Complex.instance_method(:abs)
+  end
 end
diff --git a/spec/ruby/core/complex/marshal_dump_spec.rb b/spec/ruby/core/complex/marshal_dump_spec.rb
index 116899b0ad..201d55e9e5 100644
--- a/spec/ruby/core/complex/marshal_dump_spec.rb
+++ b/spec/ruby/core/complex/marshal_dump_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Complex#marshal_dump" do
   it "is a private method" do
-    Complex.should have_private_instance_method(:marshal_dump, false)
+    Complex.private_instance_methods(false).should.include?(:marshal_dump)
   end
 
   it "dumps real and imaginary parts" do
diff --git a/spec/ruby/core/complex/negative_spec.rb b/spec/ruby/core/complex/negative_spec.rb
index 62ab89c04a..566975b8e1 100644
--- a/spec/ruby/core/complex/negative_spec.rb
+++ b/spec/ruby/core/complex/negative_spec.rb
@@ -4,10 +4,10 @@ describe "Complex#negative?" do
   it "is undefined" do
     c = Complex(1)
 
-    c.methods.should_not include(:negative?)
+    c.methods.should_not.include?(:negative?)
 
     -> {
       c.negative?
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/complex/phase_spec.rb b/spec/ruby/core/complex/phase_spec.rb
index 89574bf533..2ab90989e1 100644
--- a/spec/ruby/core/complex/phase_spec.rb
+++ b/spec/ruby/core/complex/phase_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/arg'
 
 describe "Complex#phase" do
-  it_behaves_like :complex_arg, :phase
+  it "is an alias of Complex#arg" do
+    Complex.instance_method(:phase).should == Complex.instance_method(:arg)
+  end
 end
diff --git a/spec/ruby/core/complex/polar_spec.rb b/spec/ruby/core/complex/polar_spec.rb
index 2a5d8ebd69..824211fcd0 100644
--- a/spec/ruby/core/complex/polar_spec.rb
+++ b/spec/ruby/core/complex/polar_spec.rb
@@ -7,8 +7,22 @@ describe "Complex.polar" do
   end
 
   it "raises a TypeError when given non real arguments" do
-    ->{ Complex.polar(nil)      }.should raise_error(TypeError)
-    ->{ Complex.polar(nil, nil) }.should raise_error(TypeError)
+    ->{ Complex.polar(nil)      }.should.raise(TypeError)
+    ->{ Complex.polar(nil, nil) }.should.raise(TypeError)
+  end
+
+  it "computes the real values of the real & imaginary parts from the polar form" do
+    a = Complex.polar(1.0+0.0i, Math::PI/2+0.0i)
+    a.real.should be_close(0.0, TOLERANCE)
+    a.imag.should be_close(1.0, TOLERANCE)
+    a.real.real?.should == true
+    a.imag.real?.should == true
+
+    b = Complex.polar(1+0.0i)
+    b.real.should be_close(1.0, TOLERANCE)
+    b.imag.should be_close(0.0, TOLERANCE)
+    b.real.real?.should == true
+    b.imag.real?.should == true
   end
 end
 
diff --git a/spec/ruby/core/complex/positive_spec.rb b/spec/ruby/core/complex/positive_spec.rb
index f1bad8608c..d2fb256538 100644
--- a/spec/ruby/core/complex/positive_spec.rb
+++ b/spec/ruby/core/complex/positive_spec.rb
@@ -4,10 +4,10 @@ describe "Complex#positive?" do
   it "is undefined" do
     c = Complex(1)
 
-    c.methods.should_not include(:positive?)
+    c.methods.should_not.include?(:positive?)
 
     -> {
       c.positive?
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/complex/quo_spec.rb b/spec/ruby/core/complex/quo_spec.rb
index ee6fd65c79..be0a44d532 100644
--- a/spec/ruby/core/complex/quo_spec.rb
+++ b/spec/ruby/core/complex/quo_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'shared/divide'
 
 describe "Complex#quo" do
-  it_behaves_like :complex_divide, :quo
+  it "is an alias of Complex#/" do
+    Complex.instance_method(:quo).should == Complex.instance_method(:/)
+  end
 end
diff --git a/spec/ruby/core/complex/rationalize_spec.rb b/spec/ruby/core/complex/rationalize_spec.rb
index 043b8ddf2a..d49bb52def 100644
--- a/spec/ruby/core/complex/rationalize_spec.rb
+++ b/spec/ruby/core/complex/rationalize_spec.rb
@@ -2,11 +2,11 @@ require_relative '../../spec_helper'
 
 describe "Complex#rationalize" do
   it "raises RangeError if self has non-zero imaginary part" do
-    -> { Complex(1,5).rationalize }.should raise_error(RangeError)
+    -> { Complex(1,5).rationalize }.should.raise(RangeError)
   end
 
   it "raises RangeError if self has 0.0 imaginary part" do
-    -> { Complex(1,0.0).rationalize }.should raise_error(RangeError)
+    -> { Complex(1,0.0).rationalize }.should.raise(RangeError)
   end
 
   it "returns a Rational if self has zero imaginary part" do
@@ -25,7 +25,7 @@ describe "Complex#rationalize" do
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { Complex(1,0).rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { Complex(1,0).rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { Complex(1,0).rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { Complex(1,0).rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/complex/real_spec.rb b/spec/ruby/core/complex/real_spec.rb
index 2ea791c005..41734b23f0 100644
--- a/spec/ruby/core/complex/real_spec.rb
+++ b/spec/ruby/core/complex/real_spec.rb
@@ -11,18 +11,18 @@ end
 
 describe "Complex#real?" do
   it "returns false if there is an imaginary part" do
-    Complex(2,3).real?.should be_false
+    Complex(2,3).real?.should == false
   end
 
   it "returns false if there is not an imaginary part" do
-    Complex(2).real?.should be_false
+    Complex(2).real?.should == false
   end
 
   it "returns false if the real part is Infinity" do
-    Complex(infinity_value).real?.should be_false
+    Complex(infinity_value).real?.should == false
   end
 
   it "returns false if the real part is NaN" do
-    Complex(nan_value).real?.should be_false
+    Complex(nan_value).real?.should == false
   end
 end
diff --git a/spec/ruby/core/complex/rect_spec.rb b/spec/ruby/core/complex/rect_spec.rb
index 9e95f3efc2..72f2bf9930 100644
--- a/spec/ruby/core/complex/rect_spec.rb
+++ b/spec/ruby/core/complex/rect_spec.rb
@@ -1,10 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'shared/rect'
 
 describe "Complex#rect" do
-  it_behaves_like :complex_rect, :rect
+  it "is an alias of Complex#rectangular" do
+    Complex.instance_method(:rect).should == Complex.instance_method(:rectangular)
+  end
 end
 
 describe "Complex.rect" do
-  it_behaves_like :complex_rect_class, :rect
+  it "is an alias of Complex#rectangular" do
+    Complex.method(:rect).should == Complex.method(:rectangular)
+  end
 end
diff --git a/spec/ruby/core/complex/rectangular_spec.rb b/spec/ruby/core/complex/rectangular_spec.rb
index d4b8ad9782..7789bf925e 100644
--- a/spec/ruby/core/complex/rectangular_spec.rb
+++ b/spec/ruby/core/complex/rectangular_spec.rb
@@ -1,10 +1,114 @@
 require_relative '../../spec_helper'
-require_relative 'shared/rect'
 
 describe "Complex#rectangular" do
-  it_behaves_like :complex_rect, :rectangular
+  before :each do
+    @numbers = [
+      Complex(1),
+      Complex(0, 20),
+      Complex(0, 0),
+      Complex(0.0),
+      Complex(9999999**99),
+      Complex(-20),
+      Complex.polar(76, 10)
+    ]
+  end
+
+  it "returns an Array" do
+    @numbers.each do |number|
+      number.rectangular.should.instance_of?(Array)
+    end
+  end
+
+  it "returns a two-element Array" do
+    @numbers.each do |number|
+      number.rectangular.size.should == 2
+    end
+  end
+
+  it "returns the real part of self as the first element" do
+    @numbers.each do |number|
+      number.rectangular.first.should == number.real
+    end
+  end
+
+  it "returns the imaginary part of self as the last element" do
+    @numbers.each do |number|
+      number.rectangular.last.should == number.imaginary
+    end
+  end
+
+  it "raises an ArgumentError if given any arguments" do
+    @numbers.each do |number|
+      -> { number.rectangular(number) }.should.raise(ArgumentError)
+    end
+  end
 end
 
 describe "Complex.rectangular" do
-  it_behaves_like :complex_rect_class, :rectangular
+  describe "passed a Numeric n which responds to #real? with true" do
+    it "returns a Complex with real part n and imaginary part 0" do
+      n = mock_numeric('n')
+      n.should_receive(:real?).any_number_of_times.and_return(true)
+      result = Complex.rectangular(n)
+      result.real.should == n
+      result.imag.should == 0
+    end
+  end
+
+  describe "passed a Numeric which responds to #real? with false" do
+    it "raises TypeError" do
+      n = mock_numeric('n')
+      n.should_receive(:real?).any_number_of_times.and_return(false)
+      -> { Complex.rectangular(n) }.should.raise(TypeError)
+    end
+  end
+
+  describe "passed Numerics n1 and n2 and at least one responds to #real? with false" do
+    [[false, false], [false, true], [true, false]].each do |r1, r2|
+      it "raises TypeError" do
+        n1 = mock_numeric('n1')
+        n2 = mock_numeric('n2')
+        n1.should_receive(:real?).any_number_of_times.and_return(r1)
+        n2.should_receive(:real?).any_number_of_times.and_return(r2)
+        -> { Complex.rectangular(n1, n2) }.should.raise(TypeError)
+      end
+    end
+  end
+
+  describe "passed Numerics n1 and n2 and both respond to #real? with true" do
+    it "returns a Complex with real part n1 and imaginary part n2" do
+      n1 = mock_numeric('n1')
+      n2 = mock_numeric('n2')
+      n1.should_receive(:real?).any_number_of_times.and_return(true)
+      n2.should_receive(:real?).any_number_of_times.and_return(true)
+      result = Complex.rectangular(n1, n2)
+      result.real.should == n1
+      result.imag.should == n2
+    end
+  end
+
+  describe "when passed a Complex" do
+    it "raises a TypeError when the imaginary part is not zero" do
+      -> {
+        Complex.rectangular(1.0+1i, 2)
+      }.should.raise(TypeError)
+
+      -> {
+        Complex.rectangular(1.0, 2i)
+      }.should.raise(TypeError)
+    end
+
+    it "ignores the imaginary part if it is zero" do
+      result = Complex.rectangular(1.0+0i, 2+0.0i)
+      result.real.should == 1.0
+      result.imag.should == 2
+    end
+  end
+
+  describe "passed a non-Numeric" do
+    it "raises TypeError" do
+      -> { Complex.rectangular(:sym) }.should.raise(TypeError)
+      -> { Complex.rectangular(0, :sym) }.should.raise(TypeError)
+    end
+  end
 end
diff --git a/spec/ruby/core/complex/shared/abs.rb b/spec/ruby/core/complex/shared/abs.rb
deleted file mode 100644
index 2299479341..0000000000
--- a/spec/ruby/core/complex/shared/abs.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-describe :complex_abs, shared: true do
-  it "returns the modulus: |a + bi| = sqrt((a ^ 2) + (b ^ 2))" do
-    Complex(0, 0).send(@method).should == 0
-    Complex(3, 4).send(@method).should == 5 # well-known integer case
-    Complex(-3, 4).send(@method).should == 5
-    Complex(1, -1).send(@method).should be_close(Math.sqrt(2), TOLERANCE)
-    Complex(6.5, 0).send(@method).should be_close(6.5, TOLERANCE)
-    Complex(0, -7.2).send(@method).should be_close(7.2, TOLERANCE)
-  end
-end
diff --git a/spec/ruby/core/complex/shared/arg.rb b/spec/ruby/core/complex/shared/arg.rb
deleted file mode 100644
index c81f197433..0000000000
--- a/spec/ruby/core/complex/shared/arg.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-describe :complex_arg, shared: true do
-  it "returns the argument -- i.e., the angle from (1, 0) in the complex plane" do
-    two_pi = 2 * Math::PI
-    (Complex(1, 0).send(@method) % two_pi).should be_close(0, TOLERANCE)
-    (Complex(0, 2).send(@method) % two_pi).should be_close(Math::PI * 0.5, TOLERANCE)
-    (Complex(-100, 0).send(@method) % two_pi).should be_close(Math::PI, TOLERANCE)
-    (Complex(0, -75.3).send(@method) % two_pi).should be_close(Math::PI * 1.5, TOLERANCE)
-  end
-end
diff --git a/spec/ruby/core/complex/shared/conjugate.rb b/spec/ruby/core/complex/shared/conjugate.rb
deleted file mode 100644
index d1ae47bcb6..0000000000
--- a/spec/ruby/core/complex/shared/conjugate.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-describe :complex_conjugate, shared: true do
-  it "returns the complex conjugate: conj a + bi = a - bi" do
-    Complex(3, 5).send(@method).should == Complex(3, -5)
-    Complex(3, -5).send(@method).should == Complex(3, 5)
-    Complex(-3.0, 5.2).send(@method).should be_close(Complex(-3.0, -5.2), TOLERANCE)
-    Complex(3.0, -5.2).send(@method).should be_close(Complex(3.0, 5.2), TOLERANCE)
-  end
-end
diff --git a/spec/ruby/core/complex/shared/divide.rb b/spec/ruby/core/complex/shared/divide.rb
deleted file mode 100644
index a60802c74c..0000000000
--- a/spec/ruby/core/complex/shared/divide.rb
+++ /dev/null
@@ -1,82 +0,0 @@
-describe :complex_divide, shared: true do
-  describe "with Complex" do
-    it "divides according to the usual rule for complex numbers" do
-      a = Complex((1 * 10) - (2 * 20), (1 * 20) + (2 * 10))
-      b = Complex(1, 2)
-      a.send(@method, b).should == Complex(10, 20)
-
-      c = Complex((1.5 * 100.2) - (2.1 * -30.3), (1.5 * -30.3) + (2.1 * 100.2))
-      d = Complex(1.5, 2.1)
-      # remember the floating-point arithmetic
-      c.send(@method, d).should be_close(Complex(100.2, -30.3), TOLERANCE)
-    end
-  end
-
-  describe "with Fixnum" do
-    it "divides both parts of the Complex number" do
-      Complex(20, 40).send(@method, 2).should == Complex(10, 20)
-      Complex(30, 30).send(@method, 10).should == Complex(3, 3)
-    end
-
-    it "raises a ZeroDivisionError when given zero" do
-      -> { Complex(20, 40).send(@method, 0) }.should raise_error(ZeroDivisionError)
-    end
-
-    it "produces Rational parts" do
-      Complex(5, 9).send(@method, 2).should eql(Complex(Rational(5,2), Rational(9,2)))
-    end
-  end
-
-  describe "with Bignum" do
-    it "divides both parts of the Complex number" do
-      Complex(20, 40).send(@method, 2).should == Complex(10, 20)
-      Complex(15, 16).send(@method, 2.0).should be_close(Complex(7.5, 8), TOLERANCE)
-    end
-  end
-
-  describe "with Float" do
-    it "divides both parts of the Complex number" do
-      Complex(3, 9).send(@method, 1.5).should == Complex(2, 6)
-      Complex(15, 16).send(@method, 2.0).should be_close(Complex(7.5, 8), TOLERANCE)
-    end
-
-    it "returns Complex(Infinity, Infinity) when given zero" do
-      Complex(20, 40).send(@method, 0.0).real.infinite?.should == 1
-      Complex(20, 40).send(@method, 0.0).imag.infinite?.should == 1
-      Complex(-20, 40).send(@method, 0.0).real.infinite?.should == -1
-      Complex(-20, 40).send(@method, 0.0).imag.infinite?.should == 1
-    end
-  end
-
-  describe "with Object" do
-    it "tries to coerce self into other" do
-      value = Complex(3, 9)
-
-      obj = mock("Object")
-      obj.should_receive(:coerce).with(value).and_return([4, 2])
-      value.send(@method, obj).should == 2
-    end
-  end
-
-  describe "with a Numeric which responds to #real? with true" do
-    it "returns Complex(real.quo(other), imag.quo(other))" do
-      other = mock_numeric('other')
-      real = mock_numeric('real')
-      imag = mock_numeric('imag')
-      other.should_receive(:real?).and_return(true)
-      real.should_receive(:quo).with(other).and_return(1)
-      imag.should_receive(:quo).with(other).and_return(2)
-      Complex(real, imag).send(@method, other).should == Complex(1, 2)
-    end
-  end
-
-  describe "with a Numeric which responds to #real? with false" do
-    it "coerces the passed argument to Complex and divides the resulting elements" do
-      complex = Complex(3, 0)
-      other = mock_numeric('other')
-      other.should_receive(:real?).any_number_of_times.and_return(false)
-      other.should_receive(:coerce).with(complex).and_return([5, 2])
-      complex.send(@method, other).should eql(Rational(5, 2))
-    end
-  end
-end
diff --git a/spec/ruby/core/complex/shared/image.rb b/spec/ruby/core/complex/shared/image.rb
deleted file mode 100644
index f839dbcaf9..0000000000
--- a/spec/ruby/core/complex/shared/image.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-describe :complex_image, shared: true do
-  it "returns the imaginary part of self" do
-    Complex(1, 0).send(@method).should == 0
-    Complex(2, 1).send(@method).should == 1
-    Complex(6.7, 8.9).send(@method).should == 8.9
-    Complex(1, bignum_value).send(@method).should == bignum_value
-  end
-end
diff --git a/spec/ruby/core/complex/shared/rect.rb b/spec/ruby/core/complex/shared/rect.rb
deleted file mode 100644
index 9f5de1ffeb..0000000000
--- a/spec/ruby/core/complex/shared/rect.rb
+++ /dev/null
@@ -1,94 +0,0 @@
-describe :complex_rect, shared: true do
-  before :each do
-    @numbers = [
-      Complex(1),
-      Complex(0, 20),
-      Complex(0, 0),
-      Complex(0.0),
-      Complex(9999999**99),
-      Complex(-20),
-      Complex.polar(76, 10)
-    ]
-  end
-
-  it "returns an Array" do
-    @numbers.each do |number|
-      number.send(@method).should be_an_instance_of(Array)
-    end
-  end
-
-  it "returns a two-element Array" do
-    @numbers.each do |number|
-      number.send(@method).size.should == 2
-    end
-  end
-
-  it "returns the real part of self as the first element" do
-   @numbers.each do |number|
-     number.send(@method).first.should == number.real
-   end
-  end
-
-  it "returns the imaginary part of self as the last element" do
-     @numbers.each do |number|
-       number.send(@method).last.should == number.imaginary
-     end
-  end
-
-  it "raises an ArgumentError if given any arguments" do
-    @numbers.each do |number|
-      -> { number.send(@method, number) }.should raise_error(ArgumentError)
-    end
-  end
-end
-
-describe :complex_rect_class, shared: true do
-  describe "passed a Numeric n which responds to #real? with true" do
-    it "returns a Complex with real part n and imaginary part 0" do
-      n = mock_numeric('n')
-      n.should_receive(:real?).any_number_of_times.and_return(true)
-      result = Complex.send(@method, n)
-      result.real.should == n
-      result.imag.should == 0
-    end
-  end
-
-  describe "passed a Numeric which responds to #real? with false" do
-    it "raises TypeError" do
-      n = mock_numeric('n')
-      n.should_receive(:real?).any_number_of_times.and_return(false)
-      -> { Complex.send(@method, n) }.should raise_error(TypeError)
-    end
-  end
-
-  describe "passed Numerics n1 and n2 and at least one responds to #real? with false" do
-    [[false, false], [false, true], [true, false]].each do |r1, r2|
-      it "raises TypeError" do
-        n1 = mock_numeric('n1')
-        n2 = mock_numeric('n2')
-        n1.should_receive(:real?).any_number_of_times.and_return(r1)
-        n2.should_receive(:real?).any_number_of_times.and_return(r2)
-        -> { Complex.send(@method, n1, n2) }.should raise_error(TypeError)
-      end
-    end
-  end
-
-  describe "passed Numerics n1 and n2 and both respond to #real? with true" do
-    it "returns a Complex with real part n1 and imaginary part n2" do
-      n1 = mock_numeric('n1')
-      n2 = mock_numeric('n2')
-      n1.should_receive(:real?).any_number_of_times.and_return(true)
-      n2.should_receive(:real?).any_number_of_times.and_return(true)
-      result = Complex.send(@method, n1, n2)
-      result.real.should == n1
-      result.imag.should == n2
-    end
-  end
-
-  describe "passed a non-Numeric" do
-    it "raises TypeError" do
-      -> { Complex.send(@method, :sym) }.should raise_error(TypeError)
-      -> { Complex.send(@method, 0, :sym) }.should raise_error(TypeError)
-    end
-  end
-end
diff --git a/spec/ruby/core/complex/spaceship_spec.rb b/spec/ruby/core/complex/spaceship_spec.rb
deleted file mode 100644
index 7b2849a86a..0000000000
--- a/spec/ruby/core/complex/spaceship_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Complex#<=>" do
-  ruby_version_is '2.7' do
-    it "returns nil if either self or argument has imaginary part" do
-      (Complex(5, 1) <=> Complex(2)).should be_nil
-      (Complex(1) <=> Complex(2, 1)).should be_nil
-      (5 <=> Complex(2, 1)).should be_nil
-    end
-
-    it "returns nil if argument is not numeric" do
-      (Complex(5, 1) <=> "cmp").should be_nil
-      (Complex(1) <=> "cmp").should be_nil
-      (Complex(1) <=> Object.new).should be_nil
-    end
-
-    it "returns 0, 1, or -1 if self and argument do not have imaginary part" do
-      (Complex(5) <=> Complex(2)).should == 1
-      (Complex(2) <=> Complex(3)).should == -1
-      (Complex(2) <=> Complex(2)).should == 0
-
-      (Complex(5) <=> 2).should == 1
-      (Complex(2) <=> 3).should == -1
-      (Complex(2) <=> 2).should == 0
-    end
-  end
-end
diff --git a/spec/ruby/core/complex/to_c_spec.rb b/spec/ruby/core/complex/to_c_spec.rb
new file mode 100644
index 0000000000..cd7195556c
--- /dev/null
+++ b/spec/ruby/core/complex/to_c_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+
+describe "Complex#to_c" do
+  it "returns self" do
+    value = Complex(1, 5)
+    value.to_c.should.equal?(value)
+  end
+
+  it 'returns the same value' do
+    Complex(1, 5).to_c.should == Complex(1, 5)
+  end
+end
diff --git a/spec/ruby/core/complex/to_f_spec.rb b/spec/ruby/core/complex/to_f_spec.rb
index 78e6526491..9f3265cdb9 100644
--- a/spec/ruby/core/complex/to_f_spec.rb
+++ b/spec/ruby/core/complex/to_f_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Complex#to_f" do
-  describe "when the imaginary part is Fixnum 0" do
+  describe "when the imaginary part is Integer 0" do
     it "returns the result of sending #to_f to the real part" do
       real = mock_numeric('real')
       real.should_receive(:to_f).and_return(:f)
@@ -29,13 +29,13 @@ describe "Complex#to_f" do
 
   describe "when the imaginary part is non-zero" do
     it "raises RangeError" do
-      -> { Complex(0, 1).to_f }.should raise_error(RangeError)
+      -> { Complex(0, 1).to_f }.should.raise(RangeError)
     end
   end
 
   describe "when the imaginary part is Float 0.0" do
     it "raises RangeError" do
-      -> { Complex(0, 0.0).to_f }.should raise_error(RangeError)
+      -> { Complex(0, 0.0).to_f }.should.raise(RangeError)
     end
   end
 end
diff --git a/spec/ruby/core/complex/to_i_spec.rb b/spec/ruby/core/complex/to_i_spec.rb
index 23134705ba..9149ffbbaa 100644
--- a/spec/ruby/core/complex/to_i_spec.rb
+++ b/spec/ruby/core/complex/to_i_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Complex#to_i" do
-  describe "when the imaginary part is Fixnum 0" do
+  describe "when the imaginary part is Integer 0" do
     it "returns the result of sending #to_i to the real part" do
       real = mock_numeric('real')
       real.should_receive(:to_i).and_return(:i)
@@ -29,13 +29,13 @@ describe "Complex#to_i" do
 
   describe "when the imaginary part is non-zero" do
     it "raises RangeError" do
-      -> { Complex(0, 1).to_i }.should raise_error(RangeError)
+      -> { Complex(0, 1).to_i }.should.raise(RangeError)
     end
   end
 
   describe "when the imaginary part is Float 0.0" do
     it "raises RangeError" do
-      -> { Complex(0, 0.0).to_i }.should raise_error(RangeError)
+      -> { Complex(0, 0.0).to_i }.should.raise(RangeError)
     end
   end
 end
diff --git a/spec/ruby/core/complex/to_r_spec.rb b/spec/ruby/core/complex/to_r_spec.rb
index 76a69a0b93..6587ae9e2e 100644
--- a/spec/ruby/core/complex/to_r_spec.rb
+++ b/spec/ruby/core/complex/to_r_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Complex#to_r" do
-  describe "when the imaginary part is Fixnum 0" do
+  describe "when the imaginary part is Integer 0" do
     it "returns the result of sending #to_r to the real part" do
       real = mock_numeric('real')
       real.should_receive(:to_r).and_return(:r)
@@ -29,13 +29,21 @@ describe "Complex#to_r" do
 
   describe "when the imaginary part is non-zero" do
     it "raises RangeError" do
-      -> { Complex(0, 1).to_r }.should raise_error(RangeError)
+      -> { Complex(0, 1).to_r }.should.raise(RangeError)
     end
   end
 
   describe "when the imaginary part is Float 0.0" do
-    it "raises RangeError" do
-      -> { Complex(0, 0.0).to_r }.should raise_error(RangeError)
+    ruby_version_is ''...'3.4' do
+      it "raises RangeError" do
+        -> { Complex(0, 0.0).to_r }.should.raise(RangeError)
+      end
+    end
+
+    ruby_version_is '3.4' do
+      it "returns a Rational" do
+        Complex(0, 0.0).to_r.should == 0r
+      end
     end
   end
 end
diff --git a/spec/ruby/core/complex/to_s_spec.rb b/spec/ruby/core/complex/to_s_spec.rb
index 989a7ae0b7..ceccffe470 100644
--- a/spec/ruby/core/complex/to_s_spec.rb
+++ b/spec/ruby/core/complex/to_s_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative '../numeric/fixtures/classes'
 
 describe "Complex#to_s" do
   describe "when self's real component is 0" do
@@ -41,4 +42,14 @@ describe "Complex#to_s" do
   it "returns 1+NaN*i for Complex(1, NaN)" do
     Complex(1, nan_value).to_s.should == "1+NaN*i"
   end
+
+  it "treats real and imaginary parts as strings" do
+    real = NumericSpecs::Subclass.new
+    # + because of https://bugs.ruby-lang.org/issues/20337
+    real.should_receive(:to_s).and_return(+"1")
+    imaginary = NumericSpecs::Subclass.new
+    imaginary.should_receive(:to_s).and_return("2")
+    imaginary.should_receive(:<).any_number_of_times.and_return(false)
+    Complex(real, imaginary).to_s.should == "1+2i"
+  end
 end
diff --git a/spec/ruby/core/conditionvariable/broadcast_spec.rb b/spec/ruby/core/conditionvariable/broadcast_spec.rb
new file mode 100644
index 0000000000..16c7b4cc8d
--- /dev/null
+++ b/spec/ruby/core/conditionvariable/broadcast_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../spec_helper'
+
+describe "ConditionVariable#broadcast" do
+  it "releases all threads waiting in line for this resource" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    threads = []
+    r1 = []
+    r2 = []
+
+    # large number to attempt to cause race conditions
+    100.times do |i|
+      threads << Thread.new(i) do |tid|
+        m.synchronize do
+          r1 << tid
+          cv.wait(m)
+          r2 << tid
+        end
+      end
+    end
+
+    # wait for all threads to acquire the mutex the first time
+    Thread.pass until m.synchronize { r1.size == threads.size }
+    # wait until all threads are sleeping (ie waiting)
+    Thread.pass until threads.all?(&:stop?)
+
+    r2.should.empty?
+    m.synchronize do
+      cv.broadcast
+    end
+
+    threads.each {|t| t.join }
+
+    # ensure that all threads that enter cv.wait are released
+    r2.sort.should == r1.sort
+    # note that order is not specified as broadcast results in a race
+    # condition on regaining the lock m
+  end
+end
diff --git a/spec/ruby/core/conditionvariable/marshal_dump_spec.rb b/spec/ruby/core/conditionvariable/marshal_dump_spec.rb
new file mode 100644
index 0000000000..594c178e88
--- /dev/null
+++ b/spec/ruby/core/conditionvariable/marshal_dump_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+
+describe "ConditionVariable#marshal_dump" do
+  it "raises a TypeError" do
+    cv = ConditionVariable.new
+    -> { cv.marshal_dump }.should.raise(TypeError, /can't dump/)
+  end
+end
diff --git a/spec/ruby/core/conditionvariable/signal_spec.rb b/spec/ruby/core/conditionvariable/signal_spec.rb
new file mode 100644
index 0000000000..3b266cf8c6
--- /dev/null
+++ b/spec/ruby/core/conditionvariable/signal_spec.rb
@@ -0,0 +1,76 @@
+require_relative '../../spec_helper'
+
+describe "ConditionVariable#signal" do
+  it "releases the first thread waiting in line for this resource" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    threads = []
+    r1 = []
+    r2 = []
+
+    # large number to attempt to cause race conditions
+    100.times do |i|
+      threads << Thread.new(i) do |tid|
+        m.synchronize do
+          r1 << tid
+          cv.wait(m)
+          r2 << tid
+        end
+      end
+    end
+
+    # wait for all threads to acquire the mutex the first time
+    Thread.pass until m.synchronize { r1.size == threads.size }
+    # wait until all threads are sleeping (ie waiting)
+    Thread.pass until threads.all?(&:stop?)
+
+    r2.should.empty?
+    100.times do |i|
+      m.synchronize do
+        cv.signal
+      end
+      Thread.pass until r2.size == i+1
+    end
+
+    threads.each {|t| t.join }
+
+    # ensure that all the threads that went into the cv.wait are
+    # released in the same order
+    r2.should == r1
+  end
+
+  it "allows control to be passed between a pair of threads" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    repeats = 100
+    in_synchronize = false
+
+    t1 = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        repeats.times do
+          cv.wait(m)
+          cv.signal
+        end
+      end
+    end
+
+    # Make sure t1 is waiting for a signal before launching t2.
+    Thread.pass until in_synchronize
+    Thread.pass until t1.stop?
+
+    t2 = Thread.new do
+      m.synchronize do
+        repeats.times do
+          cv.signal
+          cv.wait(m)
+        end
+      end
+    end
+
+    # Check that both threads terminated without exception
+    t1.join
+    t2.join
+    m.should_not.locked?
+  end
+end
diff --git a/spec/ruby/core/conditionvariable/wait_spec.rb b/spec/ruby/core/conditionvariable/wait_spec.rb
new file mode 100644
index 0000000000..1af53a15a2
--- /dev/null
+++ b/spec/ruby/core/conditionvariable/wait_spec.rb
@@ -0,0 +1,174 @@
+require_relative '../../spec_helper'
+
+describe "ConditionVariable#wait" do
+  it "calls #sleep on the given object" do
+    o = Object.new
+    o.should_receive(:sleep).with(1234)
+
+    cv = ConditionVariable.new
+
+    cv.wait(o, 1234)
+  end
+
+  it "can be woken up by ConditionVariable#signal" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        cv.wait(m)
+      end
+      :success
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass until th.stop?
+
+    m.synchronize { cv.signal }
+    th.value.should == :success
+  end
+
+  it "can be interrupted by Thread#run" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        cv.wait(m)
+      end
+      :success
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass until th.stop?
+
+    th.run
+    th.value.should == :success
+  end
+
+  it "can be interrupted by Thread#wakeup" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        cv.wait(m)
+      end
+      :success
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass until th.stop?
+
+    th.wakeup
+    th.value.should == :success
+  end
+
+  it "reacquires the lock even if the thread is killed" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+    owned = nil
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        begin
+          cv.wait(m)
+        ensure
+          owned = m.owned?
+          $stderr.puts "\nThe Thread doesn't own the Mutex!" unless owned
+        end
+      end
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass until th.stop?
+
+    th.kill
+    th.join
+
+    owned.should == true
+  end
+
+  it "reacquires the lock even if the thread is killed after being signaled" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+    owned = nil
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        begin
+          cv.wait(m)
+        ensure
+          owned = m.owned?
+          $stderr.puts "\nThe Thread doesn't own the Mutex!" unless owned
+        end
+      end
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass until th.stop?
+
+    m.synchronize {
+      cv.signal
+      # Wait that the thread is blocked on acquiring the Mutex
+      sleep 0.001
+      # Kill the thread, yet the thread should first acquire the Mutex before going on
+      th.kill
+    }
+
+    th.join
+    owned.should == true
+  end
+
+  it "supports multiple Threads waiting on the same ConditionVariable and Mutex" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    n_threads = 4
+    events = []
+
+    threads = n_threads.times.map {
+      Thread.new {
+        m.synchronize {
+          events << :t_in_synchronize
+          cv.wait(m)
+        }
+      }
+    }
+
+    Thread.pass until m.synchronize { events.size } == n_threads
+    Thread.pass until threads.any?(&:stop?)
+    m.synchronize do
+      threads.each { |t|
+        # Cause interactions with the waiting threads.
+        # On TruffleRuby, this causes a safepoint which has interesting
+        # interactions with the ConditionVariable.
+        bt = t.backtrace
+        bt.should.is_a?(Array)
+        bt.size.should >= 2
+      }
+    end
+
+    cv.broadcast
+    threads.each(&:join)
+  end
+end
diff --git a/spec/ruby/core/data/constants_spec.rb b/spec/ruby/core/data/constants_spec.rb
new file mode 100644
index 0000000000..ad0b1ddea7
--- /dev/null
+++ b/spec/ruby/core/data/constants_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+describe "Data" do
+  it "is a new constant" do
+    Data.superclass.should == Object
+  end
+
+  it "is not deprecated" do
+    -> { Data }.should_not complain
+  end
+end
diff --git a/spec/ruby/core/data/deconstruct_keys_spec.rb b/spec/ruby/core/data/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..7e81f966ea
--- /dev/null
+++ b/spec/ruby/core/data/deconstruct_keys_spec.rb
@@ -0,0 +1,110 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#deconstruct_keys" do
+  it "returns a hash of attributes" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys([:x, :y]).should == {x: 1, y: 2}
+  end
+
+  it "requires one argument" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    -> {
+      d.deconstruct_keys
+    }.should.raise(ArgumentError, /wrong number of arguments \(given 0, expected 1\)/)
+  end
+
+  it "returns only specified keys" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys([:x, :y]).should == {x: 1, y: 2}
+    d.deconstruct_keys([:x]    ).should == {x: 1}
+    d.deconstruct_keys([]      ).should == {}
+  end
+
+  it "accepts string attribute names" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys(['x', 'y']).should == {'x' => 1, 'y' => 2}
+  end
+
+  it "returns an empty hash when there are more keys than attributes" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys([:x, :y, :x]).should == {}
+  end
+
+  it "returns at first not existing attribute name" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys([:a, :x]).should == {}
+    d.deconstruct_keys([:x, :a]).should == {x: 1}
+  end
+
+  it "accepts nil argument and return all the attributes" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    d.deconstruct_keys(nil).should == {x: 1, y: 2}
+  end
+
+  ruby_version_is "4.0" do # https://bugs.ruby-lang.org/issues/21844
+    it "tries to convert a key with #to_str if index is not a String nor a Symbol, but responds to #to_str" do
+      klass = Data.define(:x, :y)
+      d = klass.new(1, 2)
+
+      key = mock("to_str")
+      key.should_receive(:to_str).and_return("y")
+
+      d.deconstruct_keys([key]).should == { "y" => 2 }
+    end
+
+    it "raise an error on argument position number" do
+      klass = Data.define(:x, :y)
+      d = klass.new(1, 2)
+
+      -> {
+        d.deconstruct_keys([0, 1])
+      }.should.raise(TypeError, "0 is not a symbol nor a string")
+    end
+
+    it "raises a TypeError if the conversion with #to_str does not return a String" do
+      klass = Data.define(:x, :y)
+      d = klass.new(1, 2)
+
+      key = mock("to_str")
+      key.should_receive(:to_str).and_return(0)
+
+      -> {
+        d.deconstruct_keys([key])
+      }.should raise_consistent_error(TypeError, /can't convert MockObject into String/)
+    end
+
+    it "raises TypeError if index is not a Symbol and not convertible to String" do
+      klass = Data.define(:x, :y)
+      d = klass.new(1, 2)
+
+      -> {
+        d.deconstruct_keys([0, []])
+      }.should.raise(TypeError, "0 is not a symbol nor a string")
+    end
+  end
+
+  it "raise TypeError if passed anything except nil or array" do
+    klass = Data.define(:x, :y)
+    d = klass.new(1, 2)
+
+    -> { d.deconstruct_keys('x') }.should.raise(TypeError, /expected Array or nil/)
+    -> { d.deconstruct_keys(1)   }.should.raise(TypeError, /expected Array or nil/)
+    -> { d.deconstruct_keys(:x)  }.should.raise(TypeError, /expected Array or nil/)
+    -> { d.deconstruct_keys({})  }.should.raise(TypeError, /expected Array or nil/)
+  end
+end
diff --git a/spec/ruby/core/data/deconstruct_spec.rb b/spec/ruby/core/data/deconstruct_spec.rb
new file mode 100644
index 0000000000..4ca0b87039
--- /dev/null
+++ b/spec/ruby/core/data/deconstruct_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#deconstruct" do
+  it "returns an array of attribute values" do
+    DataSpecs::Measure.new(42, "km").deconstruct.should == [42, "km"]
+  end
+end
diff --git a/spec/ruby/core/data/define_spec.rb b/spec/ruby/core/data/define_spec.rb
new file mode 100644
index 0000000000..c0b4671e39
--- /dev/null
+++ b/spec/ruby/core/data/define_spec.rb
@@ -0,0 +1,34 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data.define" do
+  it "accepts no arguments" do
+    empty_data = Data.define
+    empty_data.members.should == []
+  end
+
+  it "accepts symbols" do
+    movie = Data.define(:title, :year)
+    movie.members.should == [:title, :year]
+  end
+
+  it "accepts strings" do
+    movie = Data.define("title", "year")
+    movie.members.should == [:title, :year]
+  end
+
+  it "accepts a mix of strings and symbols" do
+    movie = Data.define("title", :year, "genre")
+    movie.members.should == [:title, :year, :genre]
+  end
+
+  it "accepts a block" do
+    movie = Data.define(:title, :year) do
+      def title_with_year
+        "#{title} (#{year})"
+      end
+    end
+    movie.members.should == [:title, :year]
+    movie.new("Matrix", 1999).title_with_year.should == "Matrix (1999)"
+  end
+end
diff --git a/spec/ruby/core/data/eql_spec.rb b/spec/ruby/core/data/eql_spec.rb
new file mode 100644
index 0000000000..6958d5de4a
--- /dev/null
+++ b/spec/ruby/core/data/eql_spec.rb
@@ -0,0 +1,63 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#eql?" do
+  it "returns true if the other is the same object" do
+    a = DataSpecs::Measure.new(42, "km")
+    a.should.eql?(a)
+  end
+
+  it "returns true if the other has all the same fields" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "km")
+    a.should.eql?(b)
+  end
+
+  it "returns false if the other is a different object or has different fields" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "mi")
+    a.should_not.eql?(b)
+  end
+
+  it "returns false if other is of a different class" do
+    a = DataSpecs::Measure.new(42, "km")
+    klass = Data.define(*DataSpecs::Measure.members)
+    b = klass.new(42, "km")
+    a.should_not.eql?(b)
+  end
+
+  it "returns false if any corresponding elements are not equal with #eql?" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42.0, "mi")
+    a.should_not.eql?(b)
+  end
+
+  context "recursive structure" do
+    it "returns true the other is the same object" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      a.should.eql?(a)
+    end
+
+    it "returns true if the other has all the same fields" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      b = DataSpecs::Measure.allocate
+      b.send(:initialize, amount: 42, unit: b)
+
+      a.should.eql?(b)
+    end
+
+    it "returns false if any corresponding elements are not equal with #eql?" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: a, unit: "km")
+
+      b = DataSpecs::Measure.allocate
+      b.send(:initialize, amount: b, unit: "mi")
+
+      a.should_not.eql?(b)
+    end
+  end
+end
diff --git a/spec/ruby/core/data/equal_value_spec.rb b/spec/ruby/core/data/equal_value_spec.rb
new file mode 100644
index 0000000000..d9a0dcff3e
--- /dev/null
+++ b/spec/ruby/core/data/equal_value_spec.rb
@@ -0,0 +1,63 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#==" do
+  it "returns true if the other is the same object" do
+    a = DataSpecs::Measure.new(42, "km")
+    a.should == a
+  end
+
+  it "returns true if the other has all the same fields" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "km")
+    a.should == b
+  end
+
+  it "returns false if the other is a different object or has different fields" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "mi")
+    a.should_not == b
+  end
+
+  it "returns false if other is of a different class" do
+    a = DataSpecs::Measure.new(42, "km")
+    klass = Data.define(*DataSpecs::Measure.members)
+    b = klass.new(42, "km")
+    a.should_not == b
+  end
+
+  it "returns false if any corresponding elements are not equal with #==" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42.0, "mi")
+    a.should_not == b
+  end
+
+  context "recursive structure" do
+    it "returns true the other is the same object" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      a.should == a
+    end
+
+    it "returns true if the other has all the same fields" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      b = DataSpecs::Measure.allocate
+      b.send(:initialize, amount: 42, unit: b)
+
+      a.should == b
+    end
+
+    it "returns false if any corresponding elements are not equal with #==" do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: a, unit: "km")
+
+      b = DataSpecs::Measure.allocate
+      b.send(:initialize, amount: b, unit: "mi")
+
+      a.should_not == b
+    end
+  end
+end
diff --git a/spec/ruby/core/data/fixtures/classes.rb b/spec/ruby/core/data/fixtures/classes.rb
new file mode 100644
index 0000000000..147293ee45
--- /dev/null
+++ b/spec/ruby/core/data/fixtures/classes.rb
@@ -0,0 +1,41 @@
+module DataSpecs
+  if Data.respond_to?(:define)
+    Measure = Data.define(:amount, :unit)
+    Single = Data.define(:value)
+
+    class MeasureWithOverriddenName < Measure
+      def self.name
+        "A"
+      end
+    end
+
+    class SingleWithOverriddenName < Single
+      def self.name
+        "A"
+      end
+    end
+
+    class DataSubclass < Data; end
+
+    MeasureSubclass = Class.new(Measure) do
+      def initialize(amount:, unit:)
+        super
+      end
+    end
+
+    Empty = Data.define()
+
+    DataWithOverriddenInitialize = Data.define(:amount, :unit) do
+      def initialize(*rest, **kw)
+        super
+        ScratchPad.record [:initialize, rest, kw]
+      end
+    end
+
+    Area = Data.define(:width, :height, :area) do
+      def initialize(width:, height:)
+        super(width: width, height: height, area: width * height)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/data/hash_spec.rb b/spec/ruby/core/data/hash_spec.rb
new file mode 100644
index 0000000000..bab146c92e
--- /dev/null
+++ b/spec/ruby/core/data/hash_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#hash" do
+  it "returns the same integer for objects with the same content" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "km")
+    a.hash.should == b.hash
+    a.hash.should.instance_of?(Integer)
+  end
+
+  it "returns different hashes for objects with different values" do
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(42, "ml")
+    a.hash.should_not == b.hash
+
+    a = DataSpecs::Measure.new(42, "km")
+    b = DataSpecs::Measure.new(13, "km")
+    a.hash.should_not == b.hash
+  end
+
+  it "returns different hashes for different classes" do
+    Data.define(:x).new(1).hash.should != Data.define(:x).new(1).hash
+  end
+end
diff --git a/spec/ruby/core/data/initialize_spec.rb b/spec/ruby/core/data/initialize_spec.rb
new file mode 100644
index 0000000000..0320ca880c
--- /dev/null
+++ b/spec/ruby/core/data/initialize_spec.rb
@@ -0,0 +1,204 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#initialize" do
+  context "with no members" do
+    ruby_bug "#21819", ""..."4.0.1" do
+      it "is frozen" do
+        data = Data.define
+
+        data.new.should.frozen?
+      end
+    end
+  end
+
+  it "accepts positional arguments" do
+    data = DataSpecs::Measure.new(42, "km")
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "accepts alternative positional arguments" do
+    data = DataSpecs::Measure[42, "km"]
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "accepts keyword arguments" do
+    data = DataSpecs::Measure.new(amount: 42, unit: "km")
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "accepts alternative keyword arguments" do
+    data = DataSpecs::Measure[amount: 42, unit: "km"]
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "accepts String keyword arguments" do
+    data = DataSpecs::Measure.new("amount" => 42, "unit" => "km")
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "accepts the last entry when a keyword is given as both String and Symbol" do
+    data = DataSpecs::Single.new("value" => -1, value: 42)
+
+    data.value.should == 42
+  end
+
+  it "accepts positional arguments with empty keyword arguments" do
+    data = DataSpecs::Single.new(42, **{})
+
+    data.value.should == 42
+
+    data = DataSpecs::Measure.new(42, "km", **{})
+
+    data.amount.should == 42
+    data.unit.should == "km"
+  end
+
+  it "raises ArgumentError if no arguments are given" do
+    -> {
+      DataSpecs::Measure.new
+    }.should.raise(ArgumentError) { |e|
+      e.message.should.include?("missing keywords: :amount, :unit")
+    }
+  end
+
+  it "raises ArgumentError if at least one argument is missing" do
+    -> {
+      DataSpecs::Measure.new(unit: "km")
+    }.should.raise(ArgumentError) { |e|
+      e.message.should.include?("missing keyword: :amount")
+    }
+  end
+
+  ruby_version_is "4.0" do # https://bugs.ruby-lang.org/issues/21844
+    it "raises ArgumentError if at least one argument is missing and other is provided as both String and Symbol" do
+      -> {
+        DataSpecs::Measure.new(unit: "km", "unit" => "km")
+      }.should.raise(ArgumentError) { |e|
+        e.message.should.include?("missing keyword: :amount")
+      }
+    end
+  end
+
+  it "raises ArgumentError if unknown keyword is given" do
+    -> {
+      DataSpecs::Measure.new(amount: 42, unit: "km", system: "metric")
+    }.should.raise(ArgumentError) { |e|
+      e.message.should.include?("unknown keyword: :system")
+    }
+  end
+
+  ruby_version_is "4.0" do # https://bugs.ruby-lang.org/issues/21844
+    it "raises ArgumentError if unknown keyword is given which is convertable to String" do
+      key = mock("to_str")
+      key.should_receive(:to_str).and_return("system")
+
+      -> {
+        DataSpecs::Measure.new(amount: 42, unit: "km", key => "metric")
+      }.should.raise(ArgumentError) { |e|
+        e.message.should.include?('unknown keyword: "system"')
+      }
+    end
+
+    it "raises TypeError when the keyword is not convertable to String" do
+      -> {
+        DataSpecs::Measure.new(1 => 2)
+      }.should.raise(TypeError) { |e|
+        e.message.should == "1 is not a symbol nor a string"
+      }
+    end
+
+    it "raises TypeError if the conversion with #to_str does not return a String" do
+      klass = Data.define(:x, :y)
+
+      key = mock("to_str")
+      key.should_receive(:to_str).and_return(0)
+
+      -> {
+        klass.new(key => 2)
+      }.should raise_consistent_error(TypeError, /can't convert MockObject into String/)
+    end
+  end
+
+  it "supports super from a subclass" do
+    ms = DataSpecs::MeasureSubclass.new(amount: 1, unit: "km")
+
+    ms.amount.should == 1
+    ms.unit.should == "km"
+  end
+
+  it "supports Data with no fields" do
+    -> { DataSpecs::Empty.new }.should_not.raise
+  end
+
+  it "can be overridden" do
+    ScratchPad.record []
+
+    measure_class = Data.define(:amount, :unit) do
+      def initialize(*, **)
+        super
+        ScratchPad << :initialize
+      end
+    end
+
+    measure_class.new(42, "m")
+    ScratchPad.recorded.should == [:initialize]
+  end
+
+  context "when it is overridden" do
+    it "is called with keyword arguments when given positional arguments" do
+      ScratchPad.clear
+      DataSpecs::DataWithOverriddenInitialize.new(42, "m")
+      ScratchPad.recorded.should == [:initialize, [], {amount: 42, unit: "m"}]
+    end
+
+    it "is called with keyword arguments when given keyword arguments" do
+      ScratchPad.clear
+      DataSpecs::DataWithOverriddenInitialize.new(amount: 42, unit: "m")
+      ScratchPad.recorded.should == [:initialize, [], {amount: 42, unit: "m"}]
+    end
+
+    it "is called with keyword arguments when given alternative positional arguments" do
+      ScratchPad.clear
+      DataSpecs::DataWithOverriddenInitialize[42, "m"]
+      ScratchPad.recorded.should == [:initialize, [], {amount: 42, unit: "m"}]
+    end
+
+    it "is called with keyword arguments when given alternative keyword arguments" do
+      ScratchPad.clear
+      DataSpecs::DataWithOverriddenInitialize[amount: 42, unit: "m"]
+      ScratchPad.recorded.should == [:initialize, [], {amount: 42, unit: "m"}]
+    end
+
+    it "accepts positional arguments with empty keyword arguments" do
+      data = DataSpecs::SingleWithOverriddenName.new(42, **{})
+
+      data.value.should == 42
+
+      data = DataSpecs::MeasureWithOverriddenName.new(42, "km", **{})
+
+      data.amount.should == 42
+      data.unit.should == "km"
+    end
+
+    # See https://github.com/ruby/psych/pull/765
+    it "can be deserialized by calling Data.instance_method(:initialize)" do
+      d1 = DataSpecs::Area.new(width: 2, height: 3)
+      d1.area.should == 6
+
+      d2 = DataSpecs::Area.allocate
+      Data.instance_method(:initialize).bind_call(d2, **d1.to_h)
+      d2.should == d1
+    end
+  end
+end
diff --git a/spec/ruby/core/data/inspect_spec.rb b/spec/ruby/core/data/inspect_spec.rb
new file mode 100644
index 0000000000..6c97a719e3
--- /dev/null
+++ b/spec/ruby/core/data/inspect_spec.rb
@@ -0,0 +1,63 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#inspect" do
+  it "returns a string representation showing members and values" do
+    a = DataSpecs::Measure.new(42, "km")
+    a.inspect.should == '#<data DataSpecs::Measure amount=42, unit="km">'
+  end
+
+  it "returns a string representation without the class name for anonymous structs" do
+    Data.define(:a).new("").inspect.should == '#<data a="">'
+  end
+
+  it "returns a string representation without the class name for structs nested in anonymous classes" do
+    c = Class.new
+    c.class_eval <<~DOC
+        Foo = Data.define(:a)
+      DOC
+
+    c::Foo.new("").inspect.should == '#<data a="">'
+  end
+
+  it "returns a string representation without the class name for structs nested in anonymous modules" do
+    m = Module.new
+    m.class_eval <<~DOC
+        Foo = Data.define(:a)
+      DOC
+
+    m::Foo.new("").inspect.should == '#<data a="">'
+  end
+
+  it "does not call #name method" do
+    struct = DataSpecs::MeasureWithOverriddenName.new(42, "km")
+    struct.inspect.should == '#<data DataSpecs::MeasureWithOverriddenName amount=42, unit="km">'
+  end
+
+  it "does not call #name method when struct is anonymous" do
+    klass = Class.new(DataSpecs::Measure) do
+      def self.name
+        "A"
+      end
+    end
+    struct = klass.new(42, "km")
+    struct.inspect.should == '#<data amount=42, unit="km">'
+  end
+
+  context "recursive structure" do
+    it "returns string representation with recursive attribute replaced with ..." do
+      a = DataSpecs::Measure.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      a.inspect.should == "#<data DataSpecs::Measure amount=42, unit=#<data DataSpecs::Measure:...>>"
+    end
+
+    it "returns string representation with recursive attribute replaced with ... when an anonymous class" do
+      klass = Class.new(DataSpecs::Measure)
+      a = klass.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      a.inspect.should =~ /#<data amount=42, unit=#<data #<Class:0x.+?>:\.\.\.>>/
+    end
+  end
+end
diff --git a/spec/ruby/core/data/members_spec.rb b/spec/ruby/core/data/members_spec.rb
new file mode 100644
index 0000000000..457a90a0d6
--- /dev/null
+++ b/spec/ruby/core/data/members_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#members" do
+  it "returns an array of attribute names" do
+    measure = DataSpecs::Measure.new(amount: 42, unit: 'km')
+    measure.members.should == [:amount, :unit]
+  end
+end
+
+describe "DataClass#members" do
+  it "returns an array of attribute names" do
+    DataSpecs::Measure.members.should == [:amount, :unit]
+  end
+
+  context "class inheriting Data" do
+    it "isn't available in a subclass" do
+      DataSpecs::DataSubclass.should_not.respond_to?(:members)
+    end
+  end
+end
diff --git a/spec/ruby/core/data/to_h_spec.rb b/spec/ruby/core/data/to_h_spec.rb
new file mode 100644
index 0000000000..41925cf3b2
--- /dev/null
+++ b/spec/ruby/core/data/to_h_spec.rb
@@ -0,0 +1,63 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#to_h" do
+  it "transforms the data object into a hash" do
+    data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+    data.to_h.should == { amount: 42, unit: 'km' }
+  end
+
+  context "with block" do
+    it "transforms [key, value] pairs returned by the block into a hash" do
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+      data.to_h { |key, value| [value, key] }.should == { 42 => :amount, 'km' => :unit }
+    end
+
+    it "passes to a block each pair's key and value as separate arguments" do
+      ScratchPad.record []
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+      data.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [[:amount, 42], [:unit, 'km']]
+
+      ScratchPad.record []
+      data.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[:amount, 42], [:unit, 'km']]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+      -> do
+        data.to_h { |k, v| [k.to_s, v*v, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        data.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+      -> do
+        data.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+
+      data.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+      data = DataSpecs::Measure.new(amount: 42, unit: 'km')
+
+      -> do
+        data.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
+    end
+  end
+end
diff --git a/spec/ruby/core/data/to_s_spec.rb b/spec/ruby/core/data/to_s_spec.rb
new file mode 100644
index 0000000000..a552e4659b
--- /dev/null
+++ b/spec/ruby/core/data/to_s_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#to_s" do
+  it "is an alias of Data#inspect" do
+    a = DataSpecs::Measure.new(42, "km")
+    a.method(:to_s).should == a.method(:inspect)
+  end
+end
diff --git a/spec/ruby/core/data/with_spec.rb b/spec/ruby/core/data/with_spec.rb
new file mode 100644
index 0000000000..b74df185c7
--- /dev/null
+++ b/spec/ruby/core/data/with_spec.rb
@@ -0,0 +1,55 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Data#with" do
+  it "returns self if given no arguments" do
+    data = DataSpecs::Measure.new(amount: 42, unit: "km")
+    data = data.with.should.equal?(data)
+  end
+
+  it "accepts keyword arguments" do
+    data = DataSpecs::Measure.new(amount: 42, unit: "km")
+    data = data.with(amount: 4, unit: "m")
+
+    data.amount.should == 4
+    data.unit.should == "m"
+  end
+
+  it "accepts String keyword arguments" do
+    data = DataSpecs::Measure.new(amount: 42, unit: "km")
+    data = data.with("amount" => 4, "unit" => "m")
+
+    data.amount.should == 4
+    data.unit.should == "m"
+  end
+
+  it "raises ArgumentError if no keyword arguments are given" do
+    data = DataSpecs::Measure.new(amount: 42, unit: "km")
+
+    -> {
+      data.with(4, "m")
+    }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 0)")
+  end
+
+  it "does not depend on the Data.new method" do
+    subclass = Class.new(DataSpecs::Measure)
+    data = subclass.new(amount: 42, unit: "km")
+
+    def subclass.new(*)
+      raise "Data.new is called"
+    end
+
+    data_copy = data.with(unit: "m")
+    data_copy.amount.should == 42
+    data_copy.unit.should == "m"
+  end
+
+  it "calls #initialize" do
+    data = DataSpecs::DataWithOverriddenInitialize.new(42, "m")
+    ScratchPad.clear
+
+    data.with(amount: 0)
+
+    ScratchPad.recorded.should == [:initialize, [], {amount: 0, unit: "m"}]
+  end
+end
diff --git a/spec/ruby/core/dir/chdir_spec.rb b/spec/ruby/core/dir/chdir_spec.rb
index 729ac403e3..2dc598e2a9 100644
--- a/spec/ruby/core/dir/chdir_spec.rb
+++ b/spec/ruby/core/dir/chdir_spec.rb
@@ -19,14 +19,14 @@ describe "Dir.chdir" do
   end
 
   it "defaults to $HOME with no arguments" do
-    if ENV['HOME']
-      Dir.chdir
-      current_dir = Dir.pwd
+    skip "$HOME not valid directory" unless ENV['HOME'] && File.directory?(ENV['HOME'])
 
-      Dir.chdir(ENV['HOME'])
-      home = Dir.pwd
-      current_dir.should == home
-    end
+    Dir.chdir
+    current_dir = Dir.pwd
+
+    Dir.chdir(ENV['HOME'])
+    home = Dir.pwd
+    current_dir.should == home
   end
 
   it "changes to the specified directory" do
@@ -70,6 +70,8 @@ describe "Dir.chdir" do
   end
 
   it "defaults to the home directory when given a block but no argument" do
+    skip "$HOME not valid directory" unless ENV['HOME'] && File.directory?(ENV['HOME'])
+
     # Windows will return a path with forward slashes for ENV["HOME"] so we have
     # to compare the route representations returned by Dir.chdir.
     current_dir = ""
@@ -88,15 +90,15 @@ describe "Dir.chdir" do
   end
 
   it "raises an Errno::ENOENT if the directory does not exist" do
-    -> { Dir.chdir DirSpecs.nonexistent }.should raise_error(Errno::ENOENT)
-    -> { Dir.chdir(DirSpecs.nonexistent) { } }.should raise_error(Errno::ENOENT)
+    -> { Dir.chdir DirSpecs.nonexistent }.should.raise(Errno::ENOENT)
+    -> { Dir.chdir(DirSpecs.nonexistent) { } }.should.raise(Errno::ENOENT)
   end
 
   it "raises an Errno::ENOENT if the original directory no longer exists" do
-    dir1 = tmp('/testdir1')
-    dir2 = tmp('/testdir2')
-    File.should_not.exist?(dir1)
-    File.should_not.exist?(dir2)
+    dir1 = tmp('testdir1')
+    dir2 = tmp('testdir2')
+    Dir.should_not.exist?(dir1)
+    Dir.should_not.exist?(dir2)
     Dir.mkdir dir1
     Dir.mkdir dir2
     begin
@@ -104,10 +106,10 @@ describe "Dir.chdir" do
         Dir.chdir dir1 do
           Dir.chdir(dir2) { Dir.unlink dir1 }
         end
-      }.should raise_error(Errno::ENOENT)
+      }.should.raise(Errno::ENOENT)
     ensure
-      Dir.unlink dir1 if File.exist?(dir1)
-      Dir.unlink dir2 if File.exist?(dir2)
+      Dir.unlink dir1 if Dir.exist?(dir1)
+      Dir.unlink dir2 if Dir.exist?(dir2)
     end
   end
 
@@ -122,3 +124,95 @@ describe "Dir.chdir" do
     Dir.pwd.should == @original
   end
 end
+
+describe "Dir#chdir" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
+
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
+
+  before :each do
+    @original = Dir.pwd
+  end
+
+  after :each do
+    Dir.chdir(@original)
+  end
+
+  it "changes the current working directory to self" do
+    dir = Dir.new(DirSpecs.mock_dir)
+    dir.chdir
+    Dir.pwd.should == DirSpecs.mock_dir
+  ensure
+    dir.close
+  end
+
+  it "changes the current working directory to self for duration of the block when a block is given" do
+    dir = Dir.new(DirSpecs.mock_dir)
+    pwd_in_block = nil
+
+    dir.chdir { pwd_in_block = Dir.pwd }
+
+    pwd_in_block.should == DirSpecs.mock_dir
+    Dir.pwd.should == @original
+  ensure
+    dir.close
+  end
+
+  it "returns 0 when successfully changing directory" do
+    dir = Dir.new(DirSpecs.mock_dir)
+    dir.chdir.should == 0
+  ensure
+    dir.close
+  end
+
+  it "returns the value of the block when a block is given" do
+    dir = Dir.new(DirSpecs.mock_dir)
+    dir.chdir { :block_value }.should == :block_value
+  ensure
+    dir.close
+  end
+
+  platform_is_not :windows do
+    it "does not raise an Errno::ENOENT if the original directory no longer exists" do
+      dir_name1 = tmp('testdir1')
+      dir_name2 = tmp('testdir2')
+      Dir.should_not.exist?(dir_name1)
+      Dir.should_not.exist?(dir_name2)
+      Dir.mkdir dir_name1
+      Dir.mkdir dir_name2
+
+      dir2 = Dir.new(dir_name2)
+
+      begin
+        Dir.chdir(dir_name1) do
+          dir2.chdir { Dir.unlink dir_name1 }
+        end
+        Dir.pwd.should == @original
+      ensure
+        Dir.unlink dir_name1 if Dir.exist?(dir_name1)
+        Dir.unlink dir_name2 if Dir.exist?(dir_name2)
+      end
+    ensure
+      dir2.close
+    end
+  end
+
+  it "always returns to the original directory when given a block" do
+    dir = Dir.new(DirSpecs.mock_dir)
+
+    begin
+      dir.chdir do
+        raise StandardError, "something bad happened"
+      end
+    rescue StandardError
+    end
+
+    Dir.pwd.should == @original
+  ensure
+    dir.close
+  end
+end
diff --git a/spec/ruby/core/dir/children_spec.rb b/spec/ruby/core/dir/children_spec.rb
index 8f6e62b463..6e6da1dd44 100644
--- a/spec/ruby/core/dir/children_spec.rb
+++ b/spec/ruby/core/dir/children_spec.rb
@@ -3,136 +3,145 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
-ruby_version_is "2.5" do
-  describe "Dir.children" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir.children" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    before :each do
-      @internal = Encoding.default_internal
-    end
+  before :each do
+    @internal = Encoding.default_internal
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    after :each do
-      Encoding.default_internal = @internal
-    end
+  after :each do
+    Encoding.default_internal = @internal
+  end
 
-    it "returns an Array of filenames in an existing directory including dotfiles" do
-      a = Dir.children(DirSpecs.mock_dir).sort
+  it "returns an Array of filenames in an existing directory including dotfiles" do
+    a = Dir.children(DirSpecs.mock_dir).sort
 
-      a.should == DirSpecs.expected_paths - %w[. ..]
+    a.should == DirSpecs.expected_paths - %w[. ..]
 
-      a = Dir.children("#{DirSpecs.mock_dir}/deeply/nested").sort
-      a.should == %w|.dotfile.ext directory|
-    end
+    a = Dir.children("#{DirSpecs.mock_dir}/deeply/nested").sort
+    a.should == %w|.dotfile.ext directory|
+  end
 
-    it "calls #to_path on non-String arguments" do
-      p = mock('path')
-      p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
-      Dir.children(p)
-    end
+  it "calls #to_path on non-String arguments" do
+    p = mock('path')
+    p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
+    Dir.children(p)
+  end
 
-    it "accepts an options Hash" do
-      a = Dir.children("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").sort
-      a.should == %w|.dotfile.ext directory|
-    end
+  it "accepts an options Hash" do
+    a = Dir.children("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").sort
+    a.should == %w|.dotfile.ext directory|
+  end
 
-    it "returns children encoded with the filesystem encoding by default" do
-      # This spec depends on the locale not being US-ASCII because if it is, the
-      # children that are not ascii_only? will be BINARY encoded.
-      children = Dir.children(File.join(DirSpecs.mock_dir, 'special')).sort
-      encoding = Encoding.find("filesystem")
-      encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
-      platform_is_not :windows do
-        children.should include("こんにちは.txt".force_encoding(encoding))
-      end
-      children.first.encoding.should equal(Encoding.find("filesystem"))
+  it "returns children encoded with the filesystem encoding by default" do
+    # This spec depends on the locale not being US-ASCII because if it is, the
+    # children that are not ascii_only? will be BINARY encoded.
+    children = Dir.children(File.join(DirSpecs.mock_dir, 'special')).sort
+    encoding = Encoding.find("filesystem")
+    encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
+    platform_is_not :windows do
+      children.should.include?("こんにちは.txt".dup.force_encoding(encoding))
     end
+    children.first.encoding.should.equal?(Encoding.find("filesystem"))
+  end
 
-    it "returns children encoded with the specified encoding" do
-      dir = File.join(DirSpecs.mock_dir, 'special')
-      children = Dir.children(dir, encoding: "euc-jp").sort
-      children.first.encoding.should equal(Encoding::EUC_JP)
-    end
+  it "returns children encoded with the specified encoding" do
+    dir = File.join(DirSpecs.mock_dir, 'special')
+    children = Dir.children(dir, encoding: "euc-jp").sort
+    children.first.encoding.should.equal?(Encoding::EUC_JP)
+  end
 
-    it "returns children transcoded to the default internal encoding" do
-      Encoding.default_internal = Encoding::EUC_KR
-      children = Dir.children(File.join(DirSpecs.mock_dir, 'special')).sort
-      children.first.encoding.should equal(Encoding::EUC_KR)
-    end
+  it "returns children transcoded to the default internal encoding" do
+    Encoding.default_internal = Encoding::EUC_KR
+    children = Dir.children(File.join(DirSpecs.mock_dir, 'special')).sort
+    children.first.encoding.should.equal?(Encoding::EUC_KR)
+  end
 
-    it "raises a SystemCallError if called with a nonexistent directory" do
-      -> { Dir.children DirSpecs.nonexistent }.should raise_error(SystemCallError)
-    end
+  it "raises a SystemCallError if called with a nonexistent directory" do
+    -> { Dir.children DirSpecs.nonexistent }.should.raise(SystemCallError)
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Dir#children" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir#children" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    before :each do
-      @internal = Encoding.default_internal
-    end
+  before :each do
+    @internal = Encoding.default_internal
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    after :each do
-      Encoding.default_internal = @internal
-      @dir.close if @dir
-    end
+  after :each do
+    Encoding.default_internal = @internal
+    @dir.close if @dir
+  end
 
-    it "returns an Array of filenames in an existing directory including dotfiles" do
-      @dir = Dir.new(DirSpecs.mock_dir)
-      a = @dir.children.sort
-      @dir.close
+  it "returns an Array of filenames in an existing directory including dotfiles" do
+    @dir = Dir.new(DirSpecs.mock_dir)
+    a = @dir.children.sort
+    @dir.close
 
-      a.should == DirSpecs.expected_paths - %w[. ..]
+    a.should == DirSpecs.expected_paths - %w[. ..]
 
-      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
-      a = @dir.children.sort
-      a.should == %w|.dotfile.ext directory|
-    end
+    @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+    a = @dir.children.sort
+    a.should == %w|.dotfile.ext directory|
+  end
 
-    it "accepts an options Hash" do
-      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
-      a = @dir.children.sort
-      a.should == %w|.dotfile.ext directory|
-    end
+  it "accepts an encoding keyword for the encoding of the entries" do
+    @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
+    dirs = @dir.to_a.sort
+    dirs.each { |d| d.encoding.should == Encoding::UTF_8 }
+  end
 
-    it "returns children encoded with the filesystem encoding by default" do
-      # This spec depends on the locale not being US-ASCII because if it is, the
-      # children that are not ascii_only? will be BINARY encoded.
-      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
-      children = @dir.children.sort
-      encoding = Encoding.find("filesystem")
-      encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
-      platform_is_not :windows do
-        children.should include("こんにちは.txt".force_encoding(encoding))
-      end
-      children.first.encoding.should equal(Encoding.find("filesystem"))
-    end
+  it "returns children encoded with the filesystem encoding by default" do
+    # This spec depends on the locale not being US-ASCII because if it is, the
+    # children that are not ascii_only? will be BINARY encoded.
+    @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+    children = @dir.children.sort
+    encoding = Encoding.find("filesystem")
+    encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
+    platform_is_not :windows do
+      children.should.include?("こんにちは.txt".dup.force_encoding(encoding))
+    end
+    children.first.encoding.should.equal?(Encoding.find("filesystem"))
+  end
 
-    it "returns children encoded with the specified encoding" do
-      path = File.join(DirSpecs.mock_dir, 'special')
-      @dir = Dir.new(path, encoding: "euc-jp")
-      children = @dir.children.sort
-      children.first.encoding.should equal(Encoding::EUC_JP)
-    end
+  it "returns children encoded with the specified encoding" do
+    path = File.join(DirSpecs.mock_dir, 'special')
+    @dir = Dir.new(path, encoding: "euc-jp")
+    children = @dir.children.sort
+    children.first.encoding.should.equal?(Encoding::EUC_JP)
+  end
 
-    it "returns children transcoded to the default internal encoding" do
-      Encoding.default_internal = Encoding::EUC_KR
-      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
-      children = @dir.children.sort
-      children.first.encoding.should equal(Encoding::EUC_KR)
-    end
+  it "returns children transcoded to the default internal encoding" do
+    Encoding.default_internal = Encoding::EUC_KR
+    @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+    children = @dir.children.sort
+    children.first.encoding.should.equal?(Encoding::EUC_KR)
+  end
+
+  it "returns the same result when called repeatedly" do
+    @dir = Dir.open DirSpecs.mock_dir
+
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
   end
 end
diff --git a/spec/ruby/core/dir/chroot_spec.rb b/spec/ruby/core/dir/chroot_spec.rb
index a5ca8943fc..79ad9759b0 100644
--- a/spec/ruby/core/dir/chroot_spec.rb
+++ b/spec/ruby/core/dir/chroot_spec.rb
@@ -21,17 +21,17 @@ platform_is_not :windows do
         end
 
         it "raises an Errno::EPERM exception if the directory exists" do
-          -> { Dir.chroot('.') }.should raise_error(Errno::EPERM)
+          -> { Dir.chroot('.') }.should.raise(Errno::EPERM)
         end
 
         it "raises a SystemCallError if the directory doesn't exist" do
-          -> { Dir.chroot('xgwhwhsjai2222jg') }.should raise_error(SystemCallError)
+          -> { Dir.chroot('xgwhwhsjai2222jg') }.should.raise(SystemCallError)
         end
 
         it "calls #to_path on non-String argument" do
           p = mock('path')
           p.should_receive(:to_path).and_return('.')
-          -> { Dir.chroot(p) }.should raise_error(Errno::EPERM)
+          -> { Dir.chroot(p) }.should.raise(Errno::EPERM)
         end
       end
     end
diff --git a/spec/ruby/core/dir/close_spec.rb b/spec/ruby/core/dir/close_spec.rb
index 5fad5eecfb..9902d98934 100644
--- a/spec/ruby/core/dir/close_spec.rb
+++ b/spec/ruby/core/dir/close_spec.rb
@@ -11,9 +11,43 @@ describe "Dir#close" do
 
   it "does not raise an IOError even if the Dir instance is closed" do
     dir = Dir.open DirSpecs.mock_dir
-    dir.close
-    -> {
-      dir.close
-    }.should_not raise_error(IOError)
+    dir.close.should == nil
+    dir.close.should == nil
+
+    platform_is_not :windows do
+      -> { dir.fileno }.should.raise(IOError, /closed directory/)
+    end
+  end
+
+  it "returns nil" do
+    dir = Dir.open DirSpecs.mock_dir
+    dir.close.should == nil
+  end
+
+  ruby_version_is ''...'3.4' do
+    platform_is_not :windows do
+      it "does not raise an error even if the file descriptor is closed with another Dir instance" do
+        dir = Dir.open DirSpecs.mock_dir
+        dir_new = Dir.for_fd(dir.fileno)
+
+        dir.close
+        dir_new.close
+
+        -> { dir.fileno }.should.raise(IOError, /closed directory/)
+        -> { dir_new.fileno }.should.raise(IOError, /closed directory/)
+      end
+    end
+  end
+
+  ruby_version_is '3.4' do
+    platform_is_not :windows do
+      it "raises an error if the file descriptor is closed with another Dir instance" do
+        dir = Dir.open DirSpecs.mock_dir
+        dir_new = Dir.for_fd(dir.fileno)
+        dir.close
+
+        -> { dir_new.close }.should.raise(Errno::EBADF, 'Bad file descriptor - closedir')
+      end
+    end
   end
 end
diff --git a/spec/ruby/core/dir/each_child_spec.rb b/spec/ruby/core/dir/each_child_spec.rb
index dcc9a456c7..4d6575df39 100644
--- a/spec/ruby/core/dir/each_child_spec.rb
+++ b/spec/ruby/core/dir/each_child_spec.rb
@@ -1,103 +1,117 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
-ruby_version_is "2.5" do
-  describe "Dir.each_child" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir.each_child" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    it "yields all names in an existing directory to the provided block" do
-      a, b = [], []
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.each_child("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each {|dir| dir.encoding.should == Encoding::UTF_8}
+  end
 
-      Dir.each_child(DirSpecs.mock_dir) {|f| a << f}
-      Dir.each_child("#{DirSpecs.mock_dir}/deeply/nested") {|f| b << f}
+  it "yields all names in an existing directory to the provided block" do
+    a, b = [], []
 
-      a.sort.should == DirSpecs.expected_paths -  %w[. ..]
-      b.sort.should == %w|.dotfile.ext directory|
-    end
+    Dir.each_child(DirSpecs.mock_dir) {|f| a << f}
+    Dir.each_child("#{DirSpecs.mock_dir}/deeply/nested") {|f| b << f}
 
-    it "returns nil when successful" do
-      Dir.each_child(DirSpecs.mock_dir) {|f| f}.should == nil
-    end
+    a.sort.should == DirSpecs.expected_paths -  %w[. ..]
+    b.sort.should == %w|.dotfile.ext directory|
+  end
 
-    it "calls #to_path on non-String arguments" do
-      p = mock('path')
-      p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
-      Dir.each_child(p).to_a
-    end
+  it "returns nil when successful" do
+    Dir.each_child(DirSpecs.mock_dir) {|f| f}.should == nil
+  end
 
-    it "raises a SystemCallError if passed a nonexistent directory" do
-      -> { Dir.each_child(DirSpecs.nonexistent) {} }.should raise_error(SystemCallError)
-    end
+  it "calls #to_path on non-String arguments" do
+    p = mock('path')
+    p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
+    Dir.each_child(p).to_a
+  end
 
-    describe "when no block is given" do
-      it "returns an Enumerator" do
-        Dir.each_child(DirSpecs.mock_dir).should be_an_instance_of(Enumerator)
-        Dir.each_child(DirSpecs.mock_dir).to_a.sort.should == DirSpecs.expected_paths - %w[. ..]
-      end
+  it "raises a SystemCallError if passed a nonexistent directory" do
+    -> { Dir.each_child(DirSpecs.nonexistent) {} }.should.raise(SystemCallError)
+  end
 
-      describe "returned Enumerator" do
-        describe "size" do
-          it "should return nil" do
-            Dir.each_child(DirSpecs.mock_dir).size.should == nil
-          end
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      Dir.each_child(DirSpecs.mock_dir).should.instance_of?(Enumerator)
+      Dir.each_child(DirSpecs.mock_dir).to_a.sort.should == DirSpecs.expected_paths - %w[. ..]
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          Dir.each_child(DirSpecs.mock_dir).size.should == nil
         end
       end
     end
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Dir#each_child" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir#each_child" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    after :each do
-      @dir.close if @dir
-    end
+  after :each do
+    @dir.close if @dir
+  end
 
-    it "yields all names in an existing directory to the provided block" do
-      a, b = [], []
-      @dir = Dir.new(DirSpecs.mock_dir)
-      @dir2 = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+  it "yields all names in an existing directory to the provided block" do
+    a, b = [], []
+    @dir = Dir.new(DirSpecs.mock_dir)
+    @dir2 = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
 
-      @dir.each_child { |f| a << f }
-      @dir2.each_child { |f| b << f }
-      @dir2.close
+    @dir.each_child { |f| a << f }
+    @dir2.each_child { |f| b << f }
+    @dir2.close
 
-      a.sort.should == DirSpecs.expected_paths - %w|. ..|
-      b.sort.should == %w|.dotfile.ext directory|
-    end
+    a.sort.should == DirSpecs.expected_paths - %w|. ..|
+    b.sort.should == %w|.dotfile.ext directory|
+  end
 
-    it "returns self when successful" do
-      @dir = Dir.new(DirSpecs.mock_dir)
-      @dir.each_child { |f| f }.should == @dir
-    end
+  it "returns self when successful" do
+    @dir = Dir.new(DirSpecs.mock_dir)
+    @dir.each_child { |f| f }.should == @dir
+  end
 
-    describe "when no block is given" do
-      it "returns an Enumerator" do
-        @dir = Dir.new(DirSpecs.mock_dir)
+  it "returns the same result when called repeatedly" do
+    @dir = Dir.open DirSpecs.mock_dir
 
-        @dir.each_child.should be_an_instance_of(Enumerator)
-        @dir.each_child.to_a.sort.should == DirSpecs.expected_paths - %w|. ..|
-      end
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      @dir = Dir.new(DirSpecs.mock_dir)
+
+      @dir.each_child.should.instance_of?(Enumerator)
+      @dir.each_child.to_a.sort.should == DirSpecs.expected_paths - %w|. ..|
+    end
 
-      describe "returned Enumerator" do
-        describe "size" do
-          it "should return nil" do
-            @dir = Dir.new(DirSpecs.mock_dir)
-            @dir.each_child.size.should == nil
-          end
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          @dir = Dir.new(DirSpecs.mock_dir)
+          @dir.each_child.size.should == nil
         end
       end
     end
diff --git a/spec/ruby/core/dir/each_spec.rb b/spec/ruby/core/dir/each_spec.rb
index 8c69a7212b..e997e340b1 100644
--- a/spec/ruby/core/dir/each_spec.rb
+++ b/spec/ruby/core/dir/each_spec.rb
@@ -32,12 +32,23 @@ describe "Dir#each" do
     @dir.each {}.should == @dir
     @dir.read.should == nil
     @dir.rewind
-    ls.should include(@dir.read)
+    ls.should.include?(@dir.read)
+  end
+
+  it "returns the same result when called repeatedly" do
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
   end
 
   describe "when no block is given" do
     it "returns an Enumerator" do
-      @dir.each.should be_an_instance_of(Enumerator)
+      @dir.each.should.instance_of?(Enumerator)
       @dir.each.to_a.sort.should == DirSpecs.expected_paths
     end
 
diff --git a/spec/ruby/core/dir/empty_spec.rb b/spec/ruby/core/dir/empty_spec.rb
index 8cc8757798..3b6b2bac85 100644
--- a/spec/ruby/core/dir/empty_spec.rb
+++ b/spec/ruby/core/dir/empty_spec.rb
@@ -12,20 +12,20 @@ describe "Dir.empty?" do
 
   it "returns true for empty directories" do
     result = Dir.empty? @empty_dir
-    result.should be_true
+    result.should == true
   end
 
   it "returns false for non-empty directories" do
     result = Dir.empty? __dir__
-    result.should be_false
+    result.should == false
   end
 
   it "returns false for a non-directory" do
     result = Dir.empty? __FILE__
-    result.should be_false
+    result.should == false
   end
 
   it "raises ENOENT for nonexistent directories" do
-    -> { Dir.empty? tmp("nonexistent") }.should raise_error(Errno::ENOENT)
+    -> { Dir.empty? tmp("nonexistent") }.should.raise(Errno::ENOENT)
   end
 end
diff --git a/spec/ruby/core/dir/entries_spec.rb b/spec/ruby/core/dir/entries_spec.rb
index 33568b6fc4..f3ca49b26d 100644
--- a/spec/ruby/core/dir/entries_spec.rb
+++ b/spec/ruby/core/dir/entries_spec.rb
@@ -35,9 +35,9 @@ describe "Dir.entries" do
     Dir.entries(p)
   end
 
-  it "accepts an options Hash" do
-    a = Dir.entries("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").sort
-    a.should == %w|. .. .dotfile.ext directory|
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.entries("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each {|dir| dir.encoding.should == Encoding::UTF_8}
   end
 
   it "returns entries encoded with the filesystem encoding by default" do
@@ -47,24 +47,24 @@ describe "Dir.entries" do
     encoding = Encoding.find("filesystem")
     encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
     platform_is_not :windows do
-      entries.should include("こんにちは.txt".force_encoding(encoding))
+      entries.should.include?("こんにちは.txt".dup.force_encoding(encoding))
     end
-    entries.first.encoding.should equal(Encoding.find("filesystem"))
+    entries.first.encoding.should.equal?(Encoding.find("filesystem"))
   end
 
   it "returns entries encoded with the specified encoding" do
     dir = File.join(DirSpecs.mock_dir, 'special')
     entries = Dir.entries(dir, encoding: "euc-jp").sort
-    entries.first.encoding.should equal(Encoding::EUC_JP)
+    entries.first.encoding.should.equal?(Encoding::EUC_JP)
   end
 
   it "returns entries transcoded to the default internal encoding" do
     Encoding.default_internal = Encoding::EUC_KR
     entries = Dir.entries(File.join(DirSpecs.mock_dir, 'special')).sort
-    entries.first.encoding.should equal(Encoding::EUC_KR)
+    entries.first.encoding.should.equal?(Encoding::EUC_KR)
   end
 
   it "raises a SystemCallError if called with a nonexistent directory" do
-    -> { Dir.entries DirSpecs.nonexistent }.should raise_error(SystemCallError)
+    -> { Dir.entries DirSpecs.nonexistent }.should.raise(SystemCallError)
   end
 end
diff --git a/spec/ruby/core/dir/exist_spec.rb b/spec/ruby/core/dir/exist_spec.rb
index 43987b0f32..05ad67dd03 100644
--- a/spec/ruby/core/dir/exist_spec.rb
+++ b/spec/ruby/core/dir/exist_spec.rb
@@ -1,6 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
-require_relative 'shared/exist'
 
 describe "Dir.exist?" do
   before :all do
@@ -11,5 +10,65 @@ describe "Dir.exist?" do
     DirSpecs.delete_mock_dirs
   end
 
-  it_behaves_like :dir_exist, :exist?
+  it "returns true if the given directory exists" do
+    Dir.exist?(__dir__).should == true
+  end
+
+  it "returns true for '.'" do
+    Dir.exist?('.').should == true
+  end
+
+  it "returns true for '..'" do
+    Dir.exist?('..').should == true
+  end
+
+  it "understands non-ASCII paths" do
+    subdir = File.join(tmp("\u{9876}\u{665}"))
+    Dir.exist?(subdir).should == false
+    Dir.mkdir(subdir)
+    Dir.exist?(subdir).should == true
+    Dir.rmdir(subdir)
+  end
+
+  it "understands relative paths" do
+    Dir.exist?(__dir__ + '/../').should == true
+  end
+
+  it "returns false if the given directory doesn't exist" do
+    Dir.exist?('y26dg27n2nwjs8a/').should == false
+  end
+
+  it "doesn't require the name to have a trailing slash" do
+    dir = __dir__
+    dir.sub!(/\/$/,'')
+    Dir.exist?(dir).should == true
+  end
+
+  it "doesn't expand paths" do
+    skip "$HOME not valid directory" unless ENV['HOME'] && File.directory?(ENV['HOME'])
+    Dir.exist?(File.expand_path('~')).should == true
+    Dir.exist?('~').should == false
+  end
+
+  it "returns false if the argument exists but is a file" do
+    File.should.exist?(__FILE__)
+    Dir.exist?(__FILE__).should == false
+  end
+
+  it "doesn't set $! when file doesn't exist" do
+    Dir.exist?("/path/to/non/existent/dir")
+    $!.should == nil
+  end
+
+  it "calls #to_path on non String arguments" do
+    p = mock('path')
+    p.should_receive(:to_path).and_return(__dir__)
+    Dir.exist?(p)
+  end
+end
+
+describe "Dir.exists?" do
+  it "has been removed" do
+    Dir.should_not.respond_to?(:exists?)
+  end
 end
diff --git a/spec/ruby/core/dir/exists_spec.rb b/spec/ruby/core/dir/exists_spec.rb
deleted file mode 100644
index 2c6f145db2..0000000000
--- a/spec/ruby/core/dir/exists_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/common'
-require_relative 'shared/exist'
-
-describe "Dir.exists?" do
-  before :all do
-    DirSpecs.create_mock_dirs
-  end
-
-  after :all do
-    DirSpecs.delete_mock_dirs
-  end
-
-  it_behaves_like :dir_exist, :exists?
-end
diff --git a/spec/ruby/core/dir/fchdir_spec.rb b/spec/ruby/core/dir/fchdir_spec.rb
new file mode 100644
index 0000000000..bd1a92b05e
--- /dev/null
+++ b/spec/ruby/core/dir/fchdir_spec.rb
@@ -0,0 +1,71 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+
+platform_is_not :windows do
+  describe "Dir.fchdir" do
+    before :all do
+      DirSpecs.create_mock_dirs
+    end
+
+    after :all do
+      DirSpecs.delete_mock_dirs
+    end
+
+    before :each do
+      @original = Dir.pwd
+    end
+
+    after :each do
+      Dir.chdir(@original)
+    end
+
+    it "changes the current working directory to the directory specified by the integer file descriptor" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      Dir.fchdir dir.fileno
+      Dir.pwd.should == DirSpecs.mock_dir
+    ensure
+      dir.close
+    end
+
+    it "returns 0 when successfully changing directory" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      Dir.fchdir(dir.fileno).should == 0
+    ensure
+      dir.close
+    end
+
+    it "returns the value of the block when a block is given" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      Dir.fchdir(dir.fileno) { :block_value }.should == :block_value
+    ensure
+      dir.close
+    end
+
+    it "changes to the specified directory for the duration of the block" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      Dir.fchdir(dir.fileno) { Dir.pwd }.should == DirSpecs.mock_dir
+      Dir.pwd.should == @original
+    ensure
+      dir.close
+    end
+
+    it "raises a SystemCallError if the file descriptor given is not valid" do
+      -> { Dir.fchdir(-1) }.should.raise(SystemCallError, "Bad file descriptor - fchdir")
+      -> { Dir.fchdir(-1) { } }.should.raise(SystemCallError, "Bad file descriptor - fchdir")
+    end
+
+    it "raises a SystemCallError if the file descriptor given is not for a directory" do
+      -> { Dir.fchdir $stdout.fileno }.should.raise(SystemCallError, /(Not a directory|Invalid argument) - fchdir/)
+      -> { Dir.fchdir($stdout.fileno) { } }.should.raise(SystemCallError, /(Not a directory|Invalid argument) - fchdir/)
+    end
+  end
+end
+
+platform_is :windows do
+  describe "Dir.fchdir" do
+    it "raises NotImplementedError" do
+      -> { Dir.fchdir 1 }.should.raise(NotImplementedError)
+      -> { Dir.fchdir(1) { } }.should.raise(NotImplementedError)
+    end
+  end
+end
diff --git a/spec/ruby/core/dir/fileno_spec.rb b/spec/ruby/core/dir/fileno_spec.rb
index 504e36d44b..3b563eb18f 100644
--- a/spec/ruby/core/dir/fileno_spec.rb
+++ b/spec/ruby/core/dir/fileno_spec.rb
@@ -27,11 +27,11 @@ describe "Dir#fileno" do
 
   if has_dir_fileno
     it "returns the file descriptor of the dir" do
-      @dir.fileno.should be_kind_of(Fixnum)
+      @dir.fileno.should.is_a?(Integer)
     end
   else
     it "raises an error when not implemented on the platform" do
-      -> { @dir.fileno }.should raise_error(NotImplementedError)
+      -> { @dir.fileno }.should.raise(NotImplementedError)
     end
   end
 end
diff --git a/spec/ruby/core/dir/fixtures/common.rb b/spec/ruby/core/dir/fixtures/common.rb
index f6708b04f7..cfec91f68f 100644
--- a/spec/ruby/core/dir/fixtures/common.rb
+++ b/spec/ruby/core/dir/fixtures/common.rb
@@ -22,7 +22,7 @@ module DirSpecs
       [0xe9].pack('U')
     ].each do |dir|
       begin
-        Dir.rmdir dir
+        Dir.rmdir mock_dir(dir)
       rescue
       end
     end
@@ -36,6 +36,8 @@ module DirSpecs
         .dotfile
         .dotsubdir/.dotfile
         .dotsubdir/nondotfile
+        nested/.dotsubir/.dotfile
+        nested/.dotsubir/nondotfile
 
         deeply/.dotfile
         deeply/nested/.dotfile.ext
@@ -79,6 +81,8 @@ module DirSpecs
         special/}
 
         special/test{1}/file[1]
+        special/{}/special
+        special/test\ +()[]{}/hello_world.erb
       ]
 
       platform_is_not :windows do
@@ -89,19 +93,40 @@ module DirSpecs
           special/|
 
           special/こんにちは.txt
+          special/\a
         ]
+        @mock_dir_files << "special/_\u{1f60e}.erb"
       end
     end
 
     @mock_dir_files
   end
 
+  def self.mock_dir_links
+    unless @mock_dir_links
+      @mock_dir_links = []
+      platform_is_not :windows do
+        @mock_dir_links += [
+          ['special/ln', 'subdir_one']
+        ]
+      end
+    end
+    @mock_dir_links
+  end
+
   def self.create_mock_dirs
+    delete_mock_dirs
     mock_dir_files.each do |name|
       file = File.join mock_dir, name
       mkdir_p File.dirname(file)
       touch file
     end
+    mock_dir_links.each do |link, target|
+      full_link = File.join mock_dir, link
+      full_target = File.join mock_dir, target
+
+      File.symlink full_target, full_link
+    end
   end
 
   def self.delete_mock_dirs
@@ -148,22 +173,31 @@ module DirSpecs
     end
   end
 
+  def self.expected_paths_with_type
+    [
+      [".", :directory],
+      ["..", :directory],
+      [".dotfile", :file],
+      [".dotsubdir", :directory],
+      ["brace", :directory],
+      ["deeply", :directory],
+      ["dir", :directory],
+      ["dir_filename_ordering", :file],
+      ["file_one.ext", :file],
+      ["file_two.ext", :file],
+      ["nested", :directory],
+      ["nondotfile", :file],
+      ["special", :directory],
+      ["subdir_one", :directory],
+      ["subdir_two", :directory],
+   ]
+  end
+
   def self.expected_paths
-    %w[
-      .
-      ..
-      .dotfile
-      .dotsubdir
-      brace
-      deeply
-      dir
-      dir_filename_ordering
-      file_one.ext
-      file_two.ext
-      nondotfile
-      special
-      subdir_one
-      subdir_two
-    ]
+    expected_paths_with_type.map(&:first)
+  end
+
+  def self.expected_glob_paths
+    expected_paths - ['..']
   end
 end
diff --git a/spec/ruby/core/dir/for_fd_spec.rb b/spec/ruby/core/dir/for_fd_spec.rb
new file mode 100644
index 0000000000..bbc75e0f8f
--- /dev/null
+++ b/spec/ruby/core/dir/for_fd_spec.rb
@@ -0,0 +1,77 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+
+quarantine! do # leads to "Errno::EBADF: Bad file descriptor - closedir" in DirSpecs.delete_mock_dirs
+platform_is_not :windows do
+  describe "Dir.for_fd" do
+    before :all do
+      DirSpecs.create_mock_dirs
+    end
+
+    after :all do
+      DirSpecs.delete_mock_dirs
+    end
+
+    before :each do
+      @original = Dir.pwd
+    end
+
+    after :each do
+      Dir.chdir(@original)
+    end
+
+    it "returns a new Dir object representing the directory specified by the given integer directory file descriptor" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      dir_new = Dir.for_fd(dir.fileno)
+
+      dir_new.should.instance_of?(Dir)
+      dir_new.children.should == dir.children
+      dir_new.fileno.should == dir.fileno
+    ensure
+      dir.close
+    end
+
+    it "returns a new Dir object without associated path" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      dir_new = Dir.for_fd(dir.fileno)
+
+      dir_new.path.should == nil
+    ensure
+      dir.close
+    end
+
+    it "calls #to_int to convert a value to an Integer" do
+      dir = Dir.new(DirSpecs.mock_dir)
+      obj = mock("fd")
+      obj.should_receive(:to_int).and_return(dir.fileno)
+
+      dir_new = Dir.for_fd(obj)
+      dir_new.fileno.should == dir.fileno
+    ensure
+      dir.close
+    end
+
+    it "raises TypeError when value cannot be converted to Integer" do
+      -> {
+        Dir.for_fd(nil)
+      }.should raise_consistent_error(TypeError, "no implicit conversion of nil into Integer")
+    end
+
+    it "raises a SystemCallError if the file descriptor given is not valid" do
+      -> { Dir.for_fd(-1) }.should.raise(SystemCallError, "Bad file descriptor - fdopendir")
+    end
+
+    it "raises a SystemCallError if the file descriptor given is not for a directory" do
+      -> { Dir.for_fd $stdout.fileno }.should.raise(SystemCallError, "Not a directory - fdopendir")
+    end
+  end
+end
+
+platform_is :windows do
+  describe "Dir.for_fd" do
+    it "raises NotImplementedError" do
+      -> { Dir.for_fd 1 }.should.raise(NotImplementedError)
+    end
+  end
+end
+end
diff --git a/spec/ruby/core/dir/foreach_spec.rb b/spec/ruby/core/dir/foreach_spec.rb
index 1560b85f8a..2a2265a029 100644
--- a/spec/ruby/core/dir/foreach_spec.rb
+++ b/spec/ruby/core/dir/foreach_spec.rb
@@ -31,17 +31,29 @@ describe "Dir.foreach" do
   end
 
   it "raises a SystemCallError if passed a nonexistent directory" do
-    -> { Dir.foreach(DirSpecs.nonexistent) {} }.should raise_error(SystemCallError)
+    -> { Dir.foreach(DirSpecs.nonexistent) {} }.should.raise(SystemCallError)
   end
 
   it "returns an Enumerator if no block given" do
-    Dir.foreach(DirSpecs.mock_dir).should be_an_instance_of(Enumerator)
+    Dir.foreach(DirSpecs.mock_dir).should.instance_of?(Enumerator)
     Dir.foreach(DirSpecs.mock_dir).to_a.sort.should == DirSpecs.expected_paths
   end
 
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.foreach("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each { |dir| dir.encoding.should == Encoding::UTF_8 }
+
+    dirs = Dir.foreach("#{DirSpecs.mock_dir}/deeply/nested", encoding: Encoding::ISO_8859_1).to_a.sort
+    dirs.each { |dir| dir.encoding.should == Encoding::ISO_8859_1 }
+
+    Dir.foreach("#{DirSpecs.mock_dir}/deeply/nested", encoding: Encoding::ISO_8859_1) do |f|
+      f.encoding.should == Encoding::ISO_8859_1
+    end
+  end
+
   describe "when no block is given" do
     it "returns an Enumerator" do
-      Dir.foreach(DirSpecs.mock_dir).should be_an_instance_of(Enumerator)
+      Dir.foreach(DirSpecs.mock_dir).should.instance_of?(Enumerator)
       Dir.foreach(DirSpecs.mock_dir).to_a.sort.should == DirSpecs.expected_paths
     end
 
diff --git a/spec/ruby/core/dir/getwd_spec.rb b/spec/ruby/core/dir/getwd_spec.rb
index 132634347c..138481821f 100644
--- a/spec/ruby/core/dir/getwd_spec.rb
+++ b/spec/ruby/core/dir/getwd_spec.rb
@@ -1,15 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/common'
-require_relative 'shared/pwd'
 
 describe "Dir.getwd" do
-  before :all do
-    DirSpecs.create_mock_dirs
+  it "is an alias of Dir.pwd" do
+    Dir.method(:getwd).should == Dir.method(:pwd)
   end
-
-  after :all do
-    DirSpecs.delete_mock_dirs
-  end
-
-  it_behaves_like :dir_pwd, :getwd
 end
diff --git a/spec/ruby/core/dir/glob_spec.rb b/spec/ruby/core/dir/glob_spec.rb
index 4b437b0e24..9e81feb15f 100644
--- a/spec/ruby/core/dir/glob_spec.rb
+++ b/spec/ruby/core/dir/glob_spec.rb
@@ -29,6 +29,23 @@ describe "Dir.glob" do
                %w!file_one.ext file_two.ext!
   end
 
+  it 'returns matching file paths when supplied :base keyword argument' do
+    dir = tmp('dir_glob_base')
+    file_1 = "#{dir}/lib/bloop.rb"
+    file_2 = "#{dir}/lib/soup.rb"
+    file_3 = "#{dir}/lib/mismatched_file_type.txt"
+    file_4 = "#{dir}/mismatched_directory.rb"
+
+    touch file_1
+    touch file_2
+    touch file_3
+    touch file_4
+
+    Dir.glob('**/*.rb', base: "#{dir}/lib").sort.should == ["bloop.rb", "soup.rb"].sort
+  ensure
+    rm_r dir
+  end
+
   it "calls #to_path to convert multiple patterns" do
     pat1 = mock('file_one.ext')
     pat1.should_receive(:to_path).and_return('file_one.ext')
@@ -39,7 +56,7 @@ describe "Dir.glob" do
   end
 
   it "matches both dot and non-dotfiles with '*' and option File::FNM_DOTMATCH" do
-    Dir.glob('*', File::FNM_DOTMATCH).sort.should == DirSpecs.expected_paths
+    Dir.glob('*', File::FNM_DOTMATCH).sort.should == DirSpecs.expected_glob_paths
   end
 
   it "matches files with any beginning with '*<non-special characters>' and option File::FNM_DOTMATCH" do
@@ -47,7 +64,7 @@ describe "Dir.glob" do
   end
 
   it "matches any files in the current directory with '**' and option File::FNM_DOTMATCH" do
-    Dir.glob('**', File::FNM_DOTMATCH).sort.should == DirSpecs.expected_paths
+    Dir.glob('**', File::FNM_DOTMATCH).sort.should == DirSpecs.expected_glob_paths
   end
 
   it "recursively matches any subdirectories except './' or '../' with '**/' from the current directory and option File::FNM_DOTMATCH" do
@@ -59,8 +76,12 @@ describe "Dir.glob" do
       deeply/nested/directory/
       deeply/nested/directory/structure/
       dir/
+      nested/
+      nested/.dotsubir/
       special/
+      special/test\ +()[]{}/
       special/test{1}/
+      special/{}/
       subdir_one/
       subdir_two/
     ]
@@ -68,6 +89,17 @@ describe "Dir.glob" do
     Dir.glob('**/', File::FNM_DOTMATCH).sort.should == expected
   end
 
+  it "recursively matches files and directories in nested dot subdirectory except . with 'nested/**/*' from the current directory and option File::FNM_DOTMATCH" do
+    expected = %w[
+      nested/.
+      nested/.dotsubir
+      nested/.dotsubir/.dotfile
+      nested/.dotsubir/nondotfile
+    ]
+
+    Dir.glob('nested/**/*', File::FNM_DOTMATCH).sort.should == expected.sort
+  end
+
   # This is a separate case to check **/ coming after a constant
   # directory as well.
   it "recursively matches any subdirectories except './' or '../' with '**/' and option File::FNM_DOTMATCH" do
@@ -80,8 +112,12 @@ describe "Dir.glob" do
       ./deeply/nested/directory/
       ./deeply/nested/directory/structure/
       ./dir/
+      ./nested/
+      ./nested/.dotsubir/
       ./special/
+      ./special/test\ +()[]{}/
       ./special/test{1}/
+      ./special/{}/
       ./subdir_one/
       ./subdir_two/
     ]
@@ -102,10 +138,18 @@ describe "Dir.glob" do
     Dir.glob('{deeply/**/,subdir_two/*}').sort.should == expected
   end
 
+  it "preserves multiple /s before a **" do
+    expected = %w[
+      deeply//nested/directory/structure
+    ]
+
+    Dir.glob('{deeply//**/structure}').sort.should == expected
+  end
+
   it "accepts a block and yields it with each elements" do
     ary = []
     ret = Dir.glob(["file_o*", "file_t*"]) { |t| ary << t }
-    ret.should be_nil
+    ret.should == nil
     ary.should == %w!file_one.ext file_two.ext!
   end
 
@@ -119,7 +163,132 @@ describe "Dir.glob" do
   end
 
   it "handles infinite directory wildcards" do
-    Dir.glob('**/**/**').empty?.should == false
+    Dir.glob('**/**/**').should_not.empty?
+  end
+
+  it "handles **/** with base keyword argument" do
+    Dir.glob('**/**', base: "dir").should == ["filename_ordering"]
+
+    expected = %w[
+      nested
+      nested/directory
+      nested/directory/structure
+      nested/directory/structure/bar
+      nested/directory/structure/baz
+      nested/directory/structure/file_one
+      nested/directory/structure/file_one.ext
+      nested/directory/structure/foo
+      nondotfile
+    ].sort
+
+    Dir.glob('**/**', base: "deeply").sort.should == expected
+  end
+
+  it "handles **/ with base keyword argument" do
+    expected = %w[
+      /
+      directory/
+      directory/structure/
+    ]
+    Dir.glob('**/', base: "deeply/nested").sort.should == expected
+  end
+
+  it "handles **/nondotfile with base keyword argument" do
+    expected = %w[
+      deeply/nondotfile
+      nondotfile
+      subdir_one/nondotfile
+      subdir_two/nondotfile
+    ]
+    Dir.glob('**/nondotfile', base: ".").sort.should == expected
+  end
+
+  it "handles **/nondotfile with base keyword argument and FNM_DOTMATCH" do
+    expected = %w[
+      .dotsubdir/nondotfile
+      deeply/nondotfile
+      nested/.dotsubir/nondotfile
+      nondotfile
+      subdir_one/nondotfile
+      subdir_two/nondotfile
+    ]
+    Dir.glob('**/nondotfile', File::FNM_DOTMATCH, base: ".").sort.should == expected
+  end
+
+  it "handles **/.dotfile with base keyword argument" do
+    expected = %w[
+      .dotfile
+      deeply/.dotfile
+      subdir_one/.dotfile
+    ]
+    Dir.glob('**/.dotfile', base: ".").sort.should == expected
+  end
+
+  it "handles **/.dotfile with base keyword argument and FNM_DOTMATCH" do
+    expected = %w[
+      .dotfile
+      .dotsubdir/.dotfile
+      deeply/.dotfile
+      nested/.dotsubir/.dotfile
+      subdir_one/.dotfile
+    ]
+    Dir.glob('**/.dotfile', File::FNM_DOTMATCH, base: ".").sort.should == expected
+  end
+
+  it "handles **/.* with base keyword argument" do
+    expected = %w[
+      .dotfile.ext
+      directory/structure/.ext
+    ].sort
+
+    Dir.glob('**/.*', base: "deeply/nested").sort.should == expected
+  end
+
+  it "handles **/.* with base keyword argument and FNM_DOTMATCH" do
+    expected = %w[
+      .
+      .dotfile.ext
+      directory/structure/.ext
+    ].sort
+
+    Dir.glob('**/.*', File::FNM_DOTMATCH, base: "deeply/nested").sort.should == expected
+  end
+
+  it "handles **/** with base keyword argument and FNM_DOTMATCH" do
+    expected = %w[
+      .
+      .dotfile.ext
+      directory
+      directory/structure
+      directory/structure/.ext
+      directory/structure/bar
+      directory/structure/baz
+      directory/structure/file_one
+      directory/structure/file_one.ext
+      directory/structure/foo
+    ].sort
+
+    Dir.glob('**/**', File::FNM_DOTMATCH, base: "deeply/nested").sort.should == expected
+  end
+
+  it "handles **/*pattern* with base keyword argument and FNM_DOTMATCH" do
+    expected = %w[
+      .dotfile.ext
+      directory/structure/file_one
+      directory/structure/file_one.ext
+    ]
+
+    Dir.glob('**/*file*', File::FNM_DOTMATCH, base: "deeply/nested").sort.should == expected
+  end
+
+  it "handles **/glob with base keyword argument and FNM_EXTGLOB" do
+    expected = %w[
+      directory/structure/bar
+      directory/structure/file_one
+      directory/structure/file_one.ext
+    ]
+
+    Dir.glob('**/*{file,bar}*', File::FNM_EXTGLOB, base: "deeply/nested").sort.should == expected
   end
 
   it "handles simple filename patterns" do
@@ -164,5 +333,30 @@ describe "Dir.glob" do
         Dir.rmdir('no_permission')
       end
     end
+
+    it "will follow symlinks when processing a `*/` pattern." do
+      expected = ['special/ln/nondotfile']
+      Dir.glob('special/*/nondotfile').should == expected
+    end
+
+    it "will not follow symlinks when recursively traversing directories" do
+      expected = %w[
+        deeply/nondotfile
+        nondotfile
+        subdir_one/nondotfile
+        subdir_two/nondotfile
+      ]
+      Dir.glob('**/nondotfile').sort.should == expected
+    end
+
+    it "will follow symlinks when testing directory after recursive directory in pattern" do
+      expected = %w[
+        deeply/nondotfile
+        special/ln/nondotfile
+        subdir_one/nondotfile
+        subdir_two/nondotfile
+      ]
+      Dir.glob('**/*/nondotfile').sort.should == expected
+    end
   end
 end
diff --git a/spec/ruby/core/dir/home_spec.rb b/spec/ruby/core/dir/home_spec.rb
index cdfc9346dc..f0b20e0687 100644
--- a/spec/ruby/core/dir/home_spec.rb
+++ b/spec/ruby/core/dir/home_spec.rb
@@ -17,29 +17,69 @@ describe "Dir.home" do
     end
 
     it "returns a non-frozen string" do
-      Dir.home.frozen?.should == false
+      Dir.home.should_not.frozen?
     end
-  end
 
-  describe "when called with the current user name" do
-    platform_is :solaris do
-      it "returns the named user's home directory from the user database" do
-        Dir.home(ENV['USER']).should == `getent passwd #{ENV['USER']}|cut -d: -f6`.chomp
+    it "returns a string with the filesystem encoding" do
+      Dir.home.encoding.should == Encoding.find("filesystem")
+    end
+
+    platform_is_not :windows do
+      it "works even if HOME is unset" do
+        ENV.delete('HOME')
+        Dir.home.should.start_with?('/')
+        Dir.home.encoding.should == Encoding.find("filesystem")
+      end
+    end
+
+    platform_is :windows do
+      it "returns the home directory with forward slashs and as UTF-8" do
+        ENV['HOME'] = "C:\\rubyspäc\\home"
+        home = Dir.home
+        home.should == "C:/rubyspäc/home"
+        home.encoding.should == Encoding::UTF_8
+      end
+
+      it "retrieves the directory from HOME, USERPROFILE, HOMEDRIVE/HOMEPATH and the WinAPI in that order" do
+        old_dirs = [ENV.delete('HOME'), ENV.delete('USERPROFILE'), ENV.delete('HOMEDRIVE'), ENV.delete('HOMEPATH')]
+
+        Dir.home.should == old_dirs[1].gsub("\\", "/")
+        ENV['HOMEDRIVE'] = "C:"
+        ENV['HOMEPATH'] = "\\rubyspec\\home1"
+        Dir.home.should == "C:/rubyspec/home1"
+        ENV['USERPROFILE'] = "C:\\rubyspec\\home2"
+        Dir.home.should == "C:/rubyspec/home2"
+        ENV['HOME'] = "C:\\rubyspec\\home3"
+        Dir.home.should == "C:/rubyspec/home3"
+      ensure
+        ENV['HOME'], ENV['USERPROFILE'], ENV['HOMEDRIVE'], ENV['HOMEPATH'] = *old_dirs
       end
     end
+  end
 
-    platform_is_not :windows, :solaris do
+  describe "when called with the current user name" do
+    platform_is_not :windows, :android, :wasi do
       it "returns the named user's home directory, from the user database" do
         Dir.home(ENV['USER']).should == `echo ~#{ENV['USER']}`.chomp
       end
     end
 
     it "returns a non-frozen string" do
-      Dir.home(ENV['USER']).frozen?.should == false
+      Dir.home(ENV['USER']).should_not.frozen?
+    end
+
+    it "returns a string with the filesystem encoding" do
+      Dir.home(ENV['USER']).encoding.should == Encoding.find("filesystem")
     end
   end
 
   it "raises an ArgumentError if the named user doesn't exist" do
-    -> { Dir.home('geuw2n288dh2k') }.should raise_error(ArgumentError)
+    -> { Dir.home('geuw2n288dh2k') }.should.raise(ArgumentError)
+  end
+
+  describe "when called with a nil user name" do
+    it "returns the current user's home directory, reading $HOME first" do
+      Dir.home(nil).should == "/rubyspec_home"
+    end
   end
 end
diff --git a/spec/ruby/core/dir/inspect_spec.rb b/spec/ruby/core/dir/inspect_spec.rb
index 37338a97d4..eabaa54ce0 100644
--- a/spec/ruby/core/dir/inspect_spec.rb
+++ b/spec/ruby/core/dir/inspect_spec.rb
@@ -11,7 +11,7 @@ describe "Dir#inspect" do
   end
 
   it "returns a String" do
-    @dir.inspect.should be_an_instance_of(String)
+    @dir.inspect.should.instance_of?(String)
   end
 
   it "includes the class name" do
@@ -19,6 +19,6 @@ describe "Dir#inspect" do
   end
 
   it "includes the directory name" do
-    @dir.inspect.should include(Dir.getwd)
+    @dir.inspect.should.include?(Dir.getwd)
   end
 end
diff --git a/spec/ruby/core/dir/mkdir_spec.rb b/spec/ruby/core/dir/mkdir_spec.rb
index c6e2f164e2..37513e417a 100644
--- a/spec/ruby/core/dir/mkdir_spec.rb
+++ b/spec/ruby/core/dir/mkdir_spec.rb
@@ -13,53 +13,73 @@ describe "Dir.mkdir" do
   it "creates the named directory with the given permissions" do
     DirSpecs.clear_dirs
 
+    nonexisting = DirSpecs.mock_dir('nonexisting')
+    default_perms = DirSpecs.mock_dir('default_perms')
+    reduced = DirSpecs.mock_dir('reduced')
     begin
-      File.should_not.exist?('nonexisting')
-      Dir.mkdir 'nonexisting'
-      File.should.exist?('nonexisting')
+      File.should_not.exist?(nonexisting)
+      Dir.mkdir nonexisting
+      File.should.exist?(nonexisting)
       platform_is_not :windows do
-        Dir.mkdir 'default_perms'
-        a = File.stat('default_perms').mode
-        Dir.mkdir 'reduced', (a - 1)
-        File.stat('reduced').mode.should_not == a
+        Dir.mkdir default_perms
+        a = File.stat(default_perms).mode
+        Dir.mkdir reduced, (a - 1)
+        File.stat(reduced).mode.should_not == a
       end
       platform_is :windows do
-        Dir.mkdir 'default_perms', 0666
-        a = File.stat('default_perms').mode
-        Dir.mkdir 'reduced', 0444
-        File.stat('reduced').mode.should_not == a
+        Dir.mkdir default_perms, 0666
+        a = File.stat(default_perms).mode
+        Dir.mkdir reduced, 0444
+        File.stat(reduced).mode.should_not == a
       end
 
-      Dir.mkdir('always_returns_0').should == 0
+      always_returns_0 = DirSpecs.mock_dir('always_returns_0')
+      Dir.mkdir(always_returns_0).should == 0
       platform_is_not(:windows) do
-        File.chmod(0777, "nonexisting","default_perms","reduced","always_returns_0")
+        File.chmod(0777, nonexisting, default_perms, reduced, always_returns_0)
       end
       platform_is_not(:windows) do
-        File.chmod(0644, "nonexisting","default_perms","reduced","always_returns_0")
+        File.chmod(0644, nonexisting, default_perms, reduced, always_returns_0)
       end
     ensure
       DirSpecs.clear_dirs
     end
   end
 
-  it "calls #to_path on non-String arguments" do
+  it "calls #to_path on non-String path arguments" do
     DirSpecs.clear_dirs
     p = mock('path')
-    p.should_receive(:to_path).and_return('nonexisting')
+    p.should_receive(:to_path).and_return(DirSpecs.mock_dir('nonexisting'))
     Dir.mkdir(p)
     DirSpecs.clear_dirs
   end
 
+  it "calls #to_int on non-Integer permissions argument" do
+    DirSpecs.clear_dirs
+    path = DirSpecs.mock_dir('nonexisting')
+    permissions = mock('permissions')
+    permissions.should_receive(:to_int).and_return(0666)
+    Dir.mkdir(path, permissions)
+    DirSpecs.clear_dirs
+  end
+
+  it "raises TypeError if non-Integer permissions argument does not have #to_int method" do
+    path = DirSpecs.mock_dir('nonexisting')
+    permissions = Object.new
+
+    -> { Dir.mkdir(path, permissions) }.should.raise(TypeError, 'no implicit conversion of Object into Integer')
+  end
+
   it "raises a SystemCallError if any of the directories in the path before the last does not exist" do
-    -> { Dir.mkdir "#{DirSpecs.nonexistent}/subdir" }.should raise_error(SystemCallError)
+    -> { Dir.mkdir "#{DirSpecs.nonexistent}/subdir" }.should.raise(SystemCallError)
   end
 
   it "raises Errno::EEXIST if the specified directory already exists" do
-    -> { Dir.mkdir("#{DirSpecs.mock_dir}/dir") }.should raise_error(Errno::EEXIST)
+    -> { Dir.mkdir("#{DirSpecs.mock_dir}/dir") }.should.raise(Errno::EEXIST)
   end
 
   it "raises Errno::EEXIST if the argument points to the existing file" do
-    -> { Dir.mkdir("#{DirSpecs.mock_dir}/file_one.ext") }.should raise_error(Errno::EEXIST)
+    -> { Dir.mkdir("#{DirSpecs.mock_dir}/file_one.ext") }.should.raise(Errno::EEXIST)
   end
 end
 
@@ -80,7 +100,7 @@ platform_is_not :windows do
       it "raises a SystemCallError when lacking adequate permissions in the parent dir" do
         Dir.mkdir @dir, 0000
 
-        -> { Dir.mkdir "#{@dir}/subdir" }.should raise_error(SystemCallError)
+        -> { Dir.mkdir "#{@dir}/subdir" }.should.raise(SystemCallError)
       end
     end
   end
diff --git a/spec/ruby/core/dir/open_spec.rb b/spec/ruby/core/dir/open_spec.rb
index 27f362320b..be01638fbc 100644
--- a/spec/ruby/core/dir/open_spec.rb
+++ b/spec/ruby/core/dir/open_spec.rb
@@ -1,6 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
-require_relative 'shared/open'
 
 describe "Dir.open" do
   before :all do
@@ -11,5 +10,75 @@ describe "Dir.open" do
     DirSpecs.delete_mock_dirs
   end
 
-  it_behaves_like :dir_open, :open
+  it "returns a Dir instance representing the specified directory" do
+    dir = Dir.open(DirSpecs.mock_dir)
+    dir.should.is_a?(Dir)
+    dir.close
+  end
+
+  it "raises a SystemCallError if the directory does not exist" do
+    -> do
+      Dir.open(DirSpecs.nonexistent)
+    end.should.raise(SystemCallError)
+  end
+
+  it "may take a block which is yielded to with the Dir instance" do
+    Dir.open(DirSpecs.mock_dir) {|dir| dir.should.is_a?(Dir)}
+  end
+
+  it "returns the value of the block if a block is given" do
+    Dir.open(DirSpecs.mock_dir) {|dir| :value }.should == :value
+  end
+
+  it "closes the Dir instance when the block exits if given a block" do
+    closed_dir = Dir.open(DirSpecs.mock_dir) { |dir| dir }
+    -> { closed_dir.read }.should.raise(IOError)
+  end
+
+  it "closes the Dir instance when the block exits the block even due to an exception" do
+    closed_dir = nil
+
+    -> do
+      Dir.open(DirSpecs.mock_dir) do |dir|
+        closed_dir = dir
+        raise "dir specs"
+      end
+    end.should.raise(RuntimeError, "dir specs")
+
+    -> { closed_dir.read }.should.raise(IOError)
+  end
+
+  it "calls #to_path on non-String arguments" do
+    p = mock('path')
+    p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
+    Dir.open(p) { true }
+  end
+
+  it "accepts an options Hash" do
+    dir = Dir.open(DirSpecs.mock_dir, encoding: "utf-8") {|d| d }
+    dir.should.is_a?(Dir)
+  end
+
+  it "calls #to_hash to convert the options object" do
+    options = mock("dir_open")
+    options.should_receive(:to_hash).and_return({ encoding: Encoding::UTF_8 })
+
+    dir = Dir.open(DirSpecs.mock_dir, **options) {|d| d }
+    dir.should.is_a?(Dir)
+  end
+
+  it "ignores the :encoding option if it is nil" do
+    dir = Dir.open(DirSpecs.mock_dir, encoding: nil) {|d| d }
+    dir.should.is_a?(Dir)
+  end
+
+  platform_is_not :windows do
+    it 'sets the close-on-exec flag for the directory file descriptor' do
+      Dir.open(DirSpecs.mock_dir) do |dir|
+        io = IO.for_fd(dir.fileno)
+        io.autoclose = false
+        io.should.close_on_exec?
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/dir/path_spec.rb b/spec/ruby/core/dir/path_spec.rb
index b1c24c406b..02ddd2cd42 100644
--- a/spec/ruby/core/dir/path_spec.rb
+++ b/spec/ruby/core/dir/path_spec.rb
@@ -1,6 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
-require_relative 'shared/path'
 
 describe "Dir#path" do
   before :all do
@@ -11,5 +10,28 @@ describe "Dir#path" do
     DirSpecs.delete_mock_dirs
   end
 
-  it_behaves_like :dir_path, :path
+  it "returns the path that was supplied to .new or .open" do
+    dir = Dir.open DirSpecs.mock_dir
+    begin
+      dir.path.should == DirSpecs.mock_dir
+    ensure
+      dir.close rescue nil
+    end
+  end
+
+  it "returns the path even when called on a closed Dir instance" do
+    dir = Dir.open DirSpecs.mock_dir
+    dir.close
+    dir.path.should == DirSpecs.mock_dir
+  end
+
+  it "returns a String with the same encoding as the argument to .open" do
+    path = DirSpecs.mock_dir.force_encoding Encoding::IBM866
+    dir = Dir.open path
+    begin
+      dir.path.encoding.should.equal?(Encoding::IBM866)
+    ensure
+      dir.close
+    end
+  end
 end
diff --git a/spec/ruby/core/dir/pos_spec.rb b/spec/ruby/core/dir/pos_spec.rb
index b382bff81f..f8ca06d778 100644
--- a/spec/ruby/core/dir/pos_spec.rb
+++ b/spec/ruby/core/dir/pos_spec.rb
@@ -1,30 +1,11 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
-require_relative 'shared/closed'
 require_relative 'shared/pos'
 
 describe "Dir#pos" do
-  before :all do
-    DirSpecs.create_mock_dirs
-  end
-
-  after :all do
-    DirSpecs.delete_mock_dirs
-  end
-
-  it_behaves_like :dir_pos, :pos
-end
-
-describe "Dir#pos" do
-  before :all do
-    DirSpecs.create_mock_dirs
+  it "is an alias of Dir#tell" do
+    Dir.instance_method(:pos).should == Dir.instance_method(:tell)
   end
-
-  after :all do
-    DirSpecs.delete_mock_dirs
-  end
-
-  it_behaves_like :dir_closed, :pos
 end
 
 describe "Dir#pos=" do
diff --git a/spec/ruby/core/dir/pwd_spec.rb b/spec/ruby/core/dir/pwd_spec.rb
index ad01286c90..70208b03d6 100644
--- a/spec/ruby/core/dir/pwd_spec.rb
+++ b/spec/ruby/core/dir/pwd_spec.rb
@@ -1,7 +1,6 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
-require_relative 'shared/pwd'
 
 describe "Dir.pwd" do
   before :all do
@@ -12,7 +11,49 @@ describe "Dir.pwd" do
     DirSpecs.delete_mock_dirs
   end
 
-  it_behaves_like :dir_pwd, :pwd
+  before :each do
+    @fs_encoding = Encoding.find('filesystem')
+  end
+
+  it "returns the current working directory" do
+    pwd = Dir.pwd
+
+    File.directory?(pwd).should == true
+
+    # On ubuntu gutsy, for example, /bin/pwd does not
+    # understand -P. With just `pwd -P`, /bin/pwd is run.
+
+    # The following uses inode rather than file names to account for
+    # case insensitive file systems like default OS/X file systems
+    platform_is_not :windows do
+      File.stat(pwd).ino.should == File.stat(`/bin/sh -c "pwd -P"`.chomp).ino
+    end
+    platform_is :windows do
+      File.stat(pwd).ino.should == File.stat(File.expand_path(`cd`.chomp)).ino
+    end
+  end
+
+  it "returns an absolute path" do
+    pwd = Dir.pwd
+    pwd.should == File.expand_path(pwd)
+  end
+
+  it "returns an absolute path even when chdir to a relative path" do
+    Dir.chdir(".") do
+      pwd = Dir.pwd
+      File.directory?(pwd).should == true
+      pwd.should == File.expand_path(pwd)
+    end
+  end
+
+  it "returns a String with the filesystem encoding" do
+    enc = Dir.pwd.encoding
+    if @fs_encoding == Encoding::US_ASCII
+      [Encoding::US_ASCII, Encoding::BINARY].should.include?(enc)
+    else
+      enc.should.equal?(@fs_encoding)
+    end
+  end
 end
 
 describe "Dir.pwd" do
diff --git a/spec/ruby/core/dir/read_spec.rb b/spec/ruby/core/dir/read_spec.rb
index 59de2e81cf..3f842457f4 100644
--- a/spec/ruby/core/dir/read_spec.rb
+++ b/spec/ruby/core/dir/read_spec.rb
@@ -15,7 +15,7 @@ describe "Dir#read" do
     # an FS does not necessarily impose order
     ls = Dir.entries DirSpecs.mock_dir
     dir = Dir.open DirSpecs.mock_dir
-    ls.should include(dir.read)
+    ls.should.include?(dir.read)
     dir.close
   end
 
@@ -39,5 +39,38 @@ describe "Dir#read" do
     entries.sort.should == DirSpecs.expected_paths
   end
 
+  platform_is_not :windows do
+    it "returns all directory entries even when encoding conversion will fail" do
+      dir = Dir.open(File.join(DirSpecs.mock_dir, 'special'))
+      utf8_entries = []
+      begin
+        while entry = dir.read
+          utf8_entries << entry
+        end
+      ensure
+        dir.close
+      end
+      old_internal_encoding = Encoding::default_internal
+      old_external_encoding = Encoding::default_external
+      Encoding.default_internal = Encoding::UTF_8
+      Encoding.default_external = Encoding::SHIFT_JIS
+      shift_jis_entries = []
+      begin
+        Dir.open(File.join(DirSpecs.mock_dir, 'special')) do |d|
+          -> {
+            while entry = d.read
+              shift_jis_entries << entry
+            end
+          }.should_not.raise
+        end
+      ensure
+        Encoding.default_internal = old_internal_encoding
+        Encoding.default_external = old_external_encoding
+      end
+      shift_jis_entries.size.should == utf8_entries.size
+      shift_jis_entries.filter { |f| f.encoding == Encoding::SHIFT_JIS }.size.should == 1
+    end
+  end
+
   it_behaves_like :dir_closed, :read
 end
diff --git a/spec/ruby/core/dir/scan_spec.rb b/spec/ruby/core/dir/scan_spec.rb
new file mode 100644
index 0000000000..3aa071337b
--- /dev/null
+++ b/spec/ruby/core/dir/scan_spec.rb
@@ -0,0 +1,224 @@
+# encoding: utf-8
+
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+require_relative '../file/fixtures/file_types'
+
+ruby_version_is "4.1" do
+  describe "Dir.scan" do
+    before :all do
+      FileSpecs.configure_types
+    end
+
+    before :all do
+      DirSpecs.create_mock_dirs
+    end
+
+    after :all do
+      DirSpecs.delete_mock_dirs
+    end
+
+    before :each do
+      @internal = Encoding.default_internal
+    end
+
+    after :each do
+      Encoding.default_internal = @internal
+    end
+
+    it "returns an Array of filename and type pairs in an existing directory including dotfiles" do
+      a = Dir.scan(DirSpecs.mock_dir).sort
+
+      a.should == DirSpecs.expected_paths_with_type - [[".", :directory], ["..", :directory]]
+
+      a = Dir.scan("#{DirSpecs.mock_dir}/deeply/nested").sort
+      a.should == [[".dotfile.ext", :file], ["directory", :directory]]
+    end
+
+    it "yields filename and type in an existing directory including dotfiles" do
+      a = []
+      Dir.scan(DirSpecs.mock_dir) do |n, t|
+        a << [n, t]
+      end
+      a.sort!
+      a.should == DirSpecs.expected_paths_with_type - [[".", :directory], ["..", :directory]]
+
+      a = []
+      Dir.scan("#{DirSpecs.mock_dir}/deeply/nested") do |n, t|
+        a << [n, t]
+      end
+      a.sort!
+      a.should == [[".dotfile.ext", :file], ["directory", :directory]]
+    end
+
+    it "calls #to_path on non-String arguments" do
+      p = mock('path')
+      p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
+      Dir.scan(p)
+    end
+
+    it "accepts an options Hash" do
+      a = Dir.scan("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").sort
+      a.should == [[".dotfile.ext", :file], ["directory", :directory]]
+    end
+
+    it "returns children names encoded with the filesystem encoding by default" do
+      # This spec depends on the locale not being US-ASCII because if it is, the
+      # children that are not ascii_only? will be BINARY encoded.
+      children = Dir.scan(File.join(DirSpecs.mock_dir, 'special')).sort
+      encoding = Encoding.find("filesystem")
+      encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
+      platform_is_not :windows do
+        children.should.include?(["こんにちは.txt".dup.force_encoding(encoding), :file])
+      end
+      children.first.first.encoding.should.equal?(Encoding.find("filesystem"))
+    end
+
+    it "returns children names encoded with the specified encoding" do
+      dir = File.join(DirSpecs.mock_dir, 'special')
+      children = Dir.scan(dir, encoding: "euc-jp").sort
+      children.first.first.encoding.should.equal?(Encoding::EUC_JP)
+    end
+
+    it "returns children names transcoded to the default internal encoding" do
+      Encoding.default_internal = Encoding::EUC_KR
+      children = Dir.scan(File.join(DirSpecs.mock_dir, 'special')).sort
+      children.first.first.encoding.should.equal?(Encoding::EUC_KR)
+    end
+
+    it "raises a SystemCallError if called with a nonexistent directory" do
+      -> { Dir.scan DirSpecs.nonexistent }.should.raise(SystemCallError)
+    end
+
+    it "handles symlink" do
+      FileSpecs.symlink do |path|
+        Dir.scan(File.dirname(path)).map(&:last).should.include?(:link)
+      end
+    end
+
+    platform_is_not :windows do
+      it "handles socket" do
+        FileSpecs.socket do |path|
+          Dir.scan(File.dirname(path)).map(&:last).should.include?(:socket)
+        end
+      end
+
+      it "handles FIFO" do
+        FileSpecs.fifo do |path|
+          Dir.scan(File.dirname(path)).map(&:last).should.include?(:fifo)
+        end
+      end
+
+      it "handles character devices" do
+        FileSpecs.character_device do |path|
+          Dir.scan(File.dirname(path)).map(&:last).should.include?(:characterSpecial)
+        end
+      end
+    end
+
+    platform_is_not :freebsd, :windows do
+      with_block_device do
+        it "handles block devices" do
+          FileSpecs.block_device do |path|
+            Dir.scan(File.dirname(path)).map(&:last).should.include?(:blockSpecial)
+          end
+        end
+      end
+    end
+  end
+
+  describe "Dir#scan" do
+    before :all do
+      DirSpecs.create_mock_dirs
+    end
+
+    after :all do
+      DirSpecs.delete_mock_dirs
+    end
+
+    before :each do
+      @internal = Encoding.default_internal
+    end
+
+    after :each do
+      Encoding.default_internal = @internal
+      @dir.close if @dir
+    end
+
+    it "returns an Array of filenames in an existing directory including dotfiles" do
+      @dir = Dir.new(DirSpecs.mock_dir)
+      a = @dir.scan.sort
+      @dir.close
+
+      a.should == DirSpecs.expected_paths_with_type - [[".", :directory], ["..", :directory]]
+
+      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+      a = @dir.scan.sort
+      a.should == [[".dotfile.ext", :file], ["directory", :directory]]
+    end
+
+    it "yields filename and type in an existing directory including dotfiles" do
+      @dir = Dir.new(DirSpecs.mock_dir)
+      a = []
+      @dir.scan do |n, t|
+        a << [n, t]
+      end
+      a.sort!
+      a.should == DirSpecs.expected_paths_with_type - [[".", :directory], ["..", :directory]]
+
+      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+      a = []
+      @dir.scan do |n, t|
+        a << [n, t]
+      end
+      a.sort!
+      a.should == [[".dotfile.ext", :file], ["directory", :directory]]
+    end
+
+    it "accepts an encoding keyword for the encoding of the entries" do
+      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
+      dirs = @dir.to_a.sort
+      dirs.each { |d| d.encoding.should == Encoding::UTF_8 }
+    end
+
+    it "returns children names encoded with the filesystem encoding by default" do
+      # This spec depends on the locale not being US-ASCII because if it is, the
+      # children that are not ascii_only? will be BINARY encoded.
+      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+      children = @dir.scan.sort
+      encoding = Encoding.find("filesystem")
+      encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
+      platform_is_not :windows do
+        children.should.include?(["こんにちは.txt".dup.force_encoding(encoding), :file])
+      end
+      children.first.first.encoding.should.equal?(Encoding.find("filesystem"))
+    end
+
+    it "returns children names encoded with the specified encoding" do
+      path = File.join(DirSpecs.mock_dir, 'special')
+      @dir = Dir.new(path, encoding: "euc-jp")
+      children = @dir.children.sort
+      children.first.encoding.should.equal?(Encoding::EUC_JP)
+    end
+
+    it "returns children names transcoded to the default internal encoding" do
+      Encoding.default_internal = Encoding::EUC_KR
+      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+      children = @dir.scan.sort
+      children.first.first.encoding.should.equal?(Encoding::EUC_KR)
+    end
+
+    it "returns the same result when called repeatedly" do
+      @dir = Dir.open DirSpecs.mock_dir
+
+      a = []
+      @dir.each {|dir| a << dir}
+
+      b = []
+      @dir.each {|dir| b << dir}
+
+      a.sort.should == b.sort
+      a.sort.should == DirSpecs.expected_paths
+    end
+  end
+end
diff --git a/spec/ruby/core/dir/shared/chroot.rb b/spec/ruby/core/dir/shared/chroot.rb
index b14a433670..e4e6103799 100644
--- a/spec/ruby/core/dir/shared/chroot.rb
+++ b/spec/ruby/core/dir/shared/chroot.rb
@@ -2,8 +2,8 @@ describe :dir_chroot_as_root, shared: true do
   before :all do
     DirSpecs.create_mock_dirs
 
-    @real_root = "../" * (File.dirname(__FILE__).count('/') - 1)
-    @ref_dir = File.join("/", Dir.new('/').entries.first)
+    @real_root = "../" * (__dir__.count('/') - 1)
+    @ref_dir = File.join("/", File.basename(Dir["/*"].first))
   end
 
   after :all do
@@ -14,24 +14,27 @@ describe :dir_chroot_as_root, shared: true do
     DirSpecs.delete_mock_dirs
   end
 
+  # Pending until https://github.com/ruby/ruby/runs/8075149420 is fixed
+  compilations_ci = ENV["GITHUB_WORKFLOW"] == "Compilations"
+
   it "can be used to change the process' root directory" do
-    -> { Dir.send(@method, File.dirname(__FILE__)) }.should_not raise_error
+    -> { Dir.send(@method, __dir__) }.should_not.raise
     File.should.exist?("/#{File.basename(__FILE__)}")
-  end
+  end unless compilations_ci
 
   it "returns 0 if successful" do
     Dir.send(@method, '/').should == 0
   end
 
   it "raises an Errno::ENOENT exception if the directory doesn't exist" do
-    -> { Dir.send(@method, 'xgwhwhsjai2222jg') }.should raise_error(Errno::ENOENT)
+    -> { Dir.send(@method, 'xgwhwhsjai2222jg') }.should.raise(Errno::ENOENT)
   end
 
   it "can be escaped from with ../" do
     Dir.send(@method, @real_root)
     File.should.exist?(@ref_dir)
     File.should_not.exist?("/#{File.basename(__FILE__)}")
-  end
+  end unless compilations_ci
 
   it "calls #to_path on non-String argument" do
     p = mock('path')
diff --git a/spec/ruby/core/dir/shared/closed.rb b/spec/ruby/core/dir/shared/closed.rb
index 17d8332c2a..c868fd6e6d 100644
--- a/spec/ruby/core/dir/shared/closed.rb
+++ b/spec/ruby/core/dir/shared/closed.rb
@@ -4,6 +4,6 @@ describe :dir_closed, shared: true do
       dir = Dir.open DirSpecs.mock_dir
       dir.close
       dir.send(@method) {}
-    }.should raise_error(IOError)
+    }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/dir/shared/delete.rb b/spec/ruby/core/dir/shared/delete.rb
index 49e88360e8..ba013e8615 100644
--- a/spec/ruby/core/dir/shared/delete.rb
+++ b/spec/ruby/core/dir/shared/delete.rb
@@ -17,26 +17,16 @@ describe :dir_delete, shared: true do
     Dir.send(@method, p)
   end
 
-  platform_is_not :solaris do
-    it "raises an Errno::ENOTEMPTY when trying to remove a nonempty directory" do
-      -> do
-        Dir.send @method, DirSpecs.mock_rmdir("nonempty")
-      end.should raise_error(Errno::ENOTEMPTY)
-    end
-  end
-
-  platform_is :solaris do
-    it "raises an Errno::EEXIST when trying to remove a nonempty directory" do
-      -> do
-        Dir.send @method, DirSpecs.mock_rmdir("nonempty")
-      end.should raise_error(Errno::EEXIST)
-    end
+  it "raises an Errno::ENOTEMPTY when trying to remove a nonempty directory" do
+    -> do
+      Dir.send @method, DirSpecs.mock_rmdir("nonempty")
+    end.should.raise(Errno::ENOTEMPTY)
   end
 
   it "raises an Errno::ENOENT when trying to remove a non-existing directory" do
     -> do
       Dir.send @method, DirSpecs.nonexistent
-    end.should raise_error(Errno::ENOENT)
+    end.should.raise(Errno::ENOENT)
   end
 
   it "raises an Errno::ENOTDIR when trying to remove a non-directory" do
@@ -44,7 +34,7 @@ describe :dir_delete, shared: true do
     touch(file)
     -> do
       Dir.send @method, file
-    end.should raise_error(Errno::ENOTDIR)
+    end.should.raise(Errno::ENOTDIR)
   end
 
   # this won't work on Windows, since chmod(0000) does not remove all permissions
@@ -56,7 +46,7 @@ describe :dir_delete, shared: true do
         File.chmod(0000, parent)
         -> do
           Dir.send @method, child
-        end.should raise_error(Errno::EACCES)
+        end.should.raise(Errno::EACCES)
       end
     end
   end
diff --git a/spec/ruby/core/dir/shared/exist.rb b/spec/ruby/core/dir/shared/exist.rb
deleted file mode 100644
index 765d1b656c..0000000000
--- a/spec/ruby/core/dir/shared/exist.rb
+++ /dev/null
@@ -1,56 +0,0 @@
-describe :dir_exist, shared: true do
-  it "returns true if the given directory exists" do
-    Dir.send(@method, File.dirname(__FILE__)).should be_true
-  end
-
-  it "returns true for '.'" do
-    Dir.send(@method, '.').should be_true
-  end
-
-  it "returns true for '..'" do
-    Dir.send(@method, '..').should be_true
-  end
-
-  it "understands non-ASCII paths" do
-    subdir = File.join(tmp("\u{9876}\u{665}"))
-    Dir.send(@method, subdir).should be_false
-    Dir.mkdir(subdir)
-    Dir.send(@method, subdir).should be_true
-    Dir.rmdir(subdir)
-  end
-
-  it "understands relative paths" do
-    Dir.send(@method, File.dirname(__FILE__) + '/../').should be_true
-  end
-
-  it "returns false if the given directory doesn't exist" do
-    Dir.send(@method, 'y26dg27n2nwjs8a/').should be_false
-  end
-
-  it "doesn't require the name to have a trailing slash" do
-    dir = File.dirname(__FILE__)
-    dir.sub!(/\/$/,'')
-    Dir.send(@method, dir).should be_true
-  end
-
-  it "doesn't expand paths" do
-    Dir.send(@method, File.expand_path('~')).should be_true
-    Dir.send(@method, '~').should be_false
-  end
-
-  it "returns false if the argument exists but is a file" do
-    File.should.exist?(__FILE__)
-    Dir.send(@method, __FILE__).should be_false
-  end
-
-  it "doesn't set $! when file doesn't exist" do
-    Dir.send(@method, "/path/to/non/existent/dir")
-    $!.should be_nil
-  end
-
-  it "calls #to_path on non String arguments" do
-    p = mock('path')
-    p.should_receive(:to_path).and_return(File.dirname(__FILE__))
-    Dir.send(@method, p)
-  end
-end
diff --git a/spec/ruby/core/dir/shared/glob.rb b/spec/ruby/core/dir/shared/glob.rb
index b47e23b41c..86aa105259 100644
--- a/spec/ruby/core/dir/shared/glob.rb
+++ b/spec/ruby/core/dir/shared/glob.rb
@@ -12,8 +12,8 @@ describe :dir_glob, shared: true do
   end
 
   it "raises an Encoding::CompatibilityError if the argument encoding is not compatible with US-ASCII" do
-    pattern = "file*".force_encoding Encoding::UTF_16BE
-    -> { Dir.send(@method, pattern) }.should raise_error(Encoding::CompatibilityError)
+    pattern = "files*".dup.force_encoding Encoding::UTF_16BE
+    -> { Dir.send(@method, pattern) }.should.raise(Encoding::CompatibilityError)
   end
 
   it "calls #to_path to convert a pattern" do
@@ -23,26 +23,29 @@ describe :dir_glob, shared: true do
     Dir.send(@method, obj).should == %w[file_one.ext]
   end
 
-  ruby_version_is ""..."2.6" do
-    it "splits the string on \\0 if there is only one string given" do
-      Dir.send(@method, "file_o*\0file_t*").should ==
-        %w!file_one.ext file_two.ext!
-    end
+  it "raises an ArgumentError if the string contains \\0" do
+    -> {Dir.send(@method, "file_o*\0file_t*")}.should.raise ArgumentError, /nul-separated/
   end
 
-  ruby_version_is "2.6"..."2.7" do
-    it "splits the string on \\0 if there is only one string given and warns" do
-      -> {
-        Dir.send(@method, "file_o*\0file_t*").should ==
-          %w!file_one.ext file_two.ext!
-      }.should complain(/warning: use glob patterns list instead of nul-separated patterns/)
-    end
+  it "result is sorted by default" do
+    result = Dir.send(@method, '*')
+    result.should == result.sort
   end
 
-  ruby_version_is "2.7" do
-    it "raises an ArgumentError if the string contains \\0" do
-      -> {Dir.send(@method, "file_o*\0file_t*")}.should raise_error ArgumentError, /nul-separated/
-    end
+  it "result is sorted with sort: true" do
+    result = Dir.send(@method, '*', sort: true)
+    result.should == result.sort
+  end
+
+  it "sort: false returns same files" do
+    result = Dir.send(@method,'*', sort: false)
+    result.sort.should == Dir.send(@method, '*').sort
+  end
+
+  it "raises an ArgumentError if sort: is not true or false" do
+    -> { Dir.send(@method, '*', sort: 0) }.should.raise ArgumentError, /expected true or false/
+    -> { Dir.send(@method, '*', sort: nil) }.should.raise ArgumentError, /expected true or false/
+    -> { Dir.send(@method, '*', sort: 'false') }.should.raise ArgumentError, /expected true or false/
   end
 
   it "matches non-dotfiles with '*'" do
@@ -53,6 +56,7 @@ describe :dir_glob, shared: true do
       dir_filename_ordering
       file_one.ext
       file_two.ext
+      nested
       nondotfile
       special
       subdir_one
@@ -70,6 +74,10 @@ describe :dir_glob, shared: true do
     Dir.send(@method, 'special/+').should == ['special/+']
   end
 
+  it "matches directories with special characters when escaped" do
+    Dir.send(@method, 'special/\{}/special').should == ["special/{}/special"]
+  end
+
   platform_is_not :windows do
     it "matches regexp special *" do
       Dir.send(@method, 'special/\*').should == ['special/*']
@@ -82,6 +90,14 @@ describe :dir_glob, shared: true do
     it "matches regexp special |" do
       Dir.send(@method, 'special/|').should == ['special/|']
     end
+
+    it "matches files with backslashes in their name" do
+      Dir.glob('special/\\\\{a,b}').should == ['special/\a']
+    end
+
+    it "matches directory with special characters in their name in complex patterns" do
+      Dir.glob("special/test +()\\[\\]\\{\\}/hello_world{.{en},}{.{html},}{+{phone},}{.{erb},}").should == ['special/test +()[]{}/hello_world.erb']
+    end
   end
 
   it "matches regexp special ^" do
@@ -120,8 +136,8 @@ describe :dir_glob, shared: true do
     Dir.send(@method, 'special/test\{1\}/*').should == ['special/test{1}/file[1]']
   end
 
-  it "matches dotfiles with '.*'" do
-    Dir.send(@method, '.*').sort.should == %w|. .. .dotfile .dotsubdir|.sort
+  it "matches dotfiles except .. with '.*'" do
+    Dir.send(@method, '.*').sort.should == %w|. .dotfile .dotsubdir|.sort
   end
 
   it "matches non-dotfiles with '*<non-special characters>'" do
@@ -156,6 +172,7 @@ describe :dir_glob, shared: true do
       dir_filename_ordering
       file_one.ext
       file_two.ext
+      nested
       nondotfile
       special
       subdir_one
@@ -165,8 +182,8 @@ describe :dir_glob, shared: true do
     Dir.send(@method, '**').sort.should == expected
   end
 
-  it "matches dotfiles in the current directory with '.**'" do
-    Dir.send(@method, '.**').sort.should == %w|. .. .dotsubdir .dotfile|.sort
+  it "matches dotfiles in the current directory except .. with '.**'" do
+    Dir.send(@method, '.**').sort.should == %w|. .dotsubdir .dotfile|.sort
   end
 
   it "recursively matches any nondot subdirectories with '**/'" do
@@ -177,8 +194,11 @@ describe :dir_glob, shared: true do
       deeply/nested/directory/
       deeply/nested/directory/structure/
       dir/
+      nested/
       special/
+      special/test\ +()[]{}/
       special/test{1}/
+      special/{}/
       subdir_one/
       subdir_two/
     ]
@@ -186,9 +206,17 @@ describe :dir_glob, shared: true do
     Dir.send(@method, '**/').sort.should == expected
   end
 
-  it "recursively matches any subdirectories including ./ and ../ with '.**/'" do
+  it "recursively matches any subdirectories except './' or '../' with '**/' from the base directory if that is specified" do
+    expected = %w[
+      nested/directory
+    ]
+
+    Dir.send(@method, '**/*ory', base: 'deeply').sort.should == expected
+  end
+
+  it "recursively matches any subdirectories including ./ with '.**/'" do
     Dir.chdir("#{DirSpecs.mock_dir}/subdir_one") do
-      Dir.send(@method, '.**/').sort.should == %w|./ ../|.sort
+      Dir.send(@method, '.**/').should == ['./']
     end
   end
 
@@ -231,7 +259,7 @@ describe :dir_glob, shared: true do
   end
 
   it "matches dot or non-dotfiles with '{,.}*'" do
-    Dir.send(@method, '{,.}*').sort.should == DirSpecs.expected_paths
+    Dir.send(@method, '{,.}*').sort.should == DirSpecs.expected_glob_paths
   end
 
   it "respects the order of {} expressions, expanding left most first" do
@@ -291,74 +319,72 @@ describe :dir_glob, shared: true do
     end
   end
 
-  ruby_version_is "2.5" do
-    context ":base option passed" do
-      before :each do
-        @mock_dir = File.expand_path tmp('dir_glob_mock')
-
-        %w[
-          a/b/x
-          a/b/c/y
-          a/b/c/d/z
-        ].each do |path|
-          file = File.join @mock_dir, path
-          mkdir_p File.dirname(file)
-          touch file
-        end
-      end
+  context ":base option passed" do
+    before :each do
+      @mock_dir = File.expand_path tmp('dir_glob_mock')
 
-      after :each do
-        rm_r @mock_dir
+      %w[
+        a/b/x
+        a/b/c/y
+        a/b/c/d/z
+      ].each do |path|
+        file = File.join @mock_dir, path
+        mkdir_p File.dirname(file)
+        touch file
       end
+    end
 
-      it "matches entries only from within the specified directory" do
-        path = File.join(@mock_dir, "a/b/c")
-        Dir.send(@method, "*", base: path).sort.should == %w( d y )
-      end
+    after :each do
+      rm_r @mock_dir
+    end
 
-      it "accepts both relative and absolute paths" do
-        require 'pathname'
+    it "matches entries only from within the specified directory" do
+      path = File.join(@mock_dir, "a/b/c")
+      Dir.send(@method, "*", base: path).sort.should == %w( d y )
+    end
 
-        path_abs = File.join(@mock_dir, "a/b/c")
-        path_rel = Pathname.new(path_abs).relative_path_from(Pathname.new(Dir.pwd))
+    it "accepts both relative and absolute paths" do
+      require 'pathname'
 
-        result_abs = Dir.send(@method, "*", base: path_abs).sort
-        result_rel = Dir.send(@method, "*", base: path_rel).sort
+      path_abs = File.join(@mock_dir, "a/b/c")
+      path_rel = Pathname.new(path_abs).relative_path_from(Pathname.new(Dir.pwd))
 
-        result_abs.should == %w( d y )
-        result_rel.should == %w( d y )
-      end
+      result_abs = Dir.send(@method, "*", base: path_abs).sort
+      result_rel = Dir.send(@method, "*", base: path_rel).sort
 
-      it "returns [] if specified path does not exist" do
-        path = File.join(@mock_dir, "fake-name")
-        File.should_not.exist?(path)
+      result_abs.should == %w( d y )
+      result_rel.should == %w( d y )
+    end
 
-        Dir.send(@method, "*", base: path).should == []
-      end
+    it "returns [] if specified path does not exist" do
+      path = File.join(@mock_dir, "fake-name")
+      File.should_not.exist?(path)
 
-      it "returns [] if specified path is a file" do
-        path = File.join(@mock_dir, "a/b/x")
-        File.should.exist?(path)
+      Dir.send(@method, "*", base: path).should == []
+    end
 
-        Dir.send(@method, "*", base: path).should == []
-      end
+    it "returns [] if specified path is a file" do
+      path = File.join(@mock_dir, "a/b/x")
+      File.should.exist?(path)
 
-      it "raises TypeError when cannot convert value to string" do
-        -> {
-          Dir.send(@method, "*", base: [])
-        }.should raise_error(TypeError)
-      end
+      Dir.send(@method, "*", base: path).should == []
+    end
 
-      it "handles '' as current directory path" do
-        Dir.chdir @mock_dir do
-          Dir.send(@method, "*", base: "").should == %w( a )
-        end
+    it "raises TypeError when cannot convert value to string" do
+      -> {
+        Dir.send(@method, "*", base: [])
+      }.should.raise(TypeError)
+    end
+
+    it "handles '' as current directory path" do
+      Dir.chdir @mock_dir do
+        Dir.send(@method, "*", base: "").should == %w( a )
       end
+    end
 
-      it "handles nil as current directory path" do
-        Dir.chdir @mock_dir do
-          Dir.send(@method, "*", base: nil).should == %w( a )
-        end
+    it "handles nil as current directory path" do
+      Dir.chdir @mock_dir do
+        Dir.send(@method, "*", base: nil).should == %w( a )
       end
     end
   end
diff --git a/spec/ruby/core/dir/shared/open.rb b/spec/ruby/core/dir/shared/open.rb
deleted file mode 100644
index 76b08dc288..0000000000
--- a/spec/ruby/core/dir/shared/open.rb
+++ /dev/null
@@ -1,73 +0,0 @@
-describe :dir_open, shared: true do
-  it "returns a Dir instance representing the specified directory" do
-    dir = Dir.send(@method, DirSpecs.mock_dir)
-    dir.should be_kind_of(Dir)
-    dir.close
-  end
-
-  it "raises a SystemCallError if the directory does not exist" do
-    -> do
-      Dir.send @method, DirSpecs.nonexistent
-    end.should raise_error(SystemCallError)
-  end
-
-  it "may take a block which is yielded to with the Dir instance" do
-    Dir.send(@method, DirSpecs.mock_dir) {|dir| dir.should be_kind_of(Dir)}
-  end
-
-  it "returns the value of the block if a block is given" do
-    Dir.send(@method, DirSpecs.mock_dir) {|dir| :value }.should == :value
-  end
-
-  it "closes the Dir instance when the block exits if given a block" do
-    closed_dir = Dir.send(@method, DirSpecs.mock_dir) { |dir| dir }
-    -> { closed_dir.read }.should raise_error(IOError)
-  end
-
-  it "closes the Dir instance when the block exits the block even due to an exception" do
-    closed_dir = nil
-
-    -> do
-      Dir.send(@method, DirSpecs.mock_dir) do |dir|
-        closed_dir = dir
-        raise "dir specs"
-      end
-    end.should raise_error(RuntimeError, "dir specs")
-
-    -> { closed_dir.read }.should raise_error(IOError)
-  end
-
-  it "calls #to_path on non-String arguments" do
-    p = mock('path')
-    p.should_receive(:to_path).and_return(DirSpecs.mock_dir)
-    Dir.send(@method, p) { true }
-  end
-
-  it "accepts an options Hash" do
-    dir = Dir.send(@method, DirSpecs.mock_dir, encoding: "utf-8") {|d| d }
-    dir.should be_kind_of(Dir)
-  end
-
-  it "calls #to_hash to convert the options object" do
-    options = mock("dir_open")
-    options.should_receive(:to_hash).and_return({ encoding: Encoding::UTF_8 })
-
-    dir = Dir.send(@method, DirSpecs.mock_dir, **options) {|d| d }
-    dir.should be_kind_of(Dir)
-  end
-
-  it "ignores the :encoding option if it is nil" do
-    dir = Dir.send(@method, DirSpecs.mock_dir, encoding: nil) {|d| d }
-    dir.should be_kind_of(Dir)
-  end
-
-  platform_is_not :windows do
-    it 'sets the close-on-exec flag for the directory file descriptor' do
-      Dir.send(@method, DirSpecs.mock_dir) do |dir|
-        io = IO.for_fd(dir.fileno)
-        io.autoclose = false
-        io.close_on_exec?.should == true
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/dir/shared/path.rb b/spec/ruby/core/dir/shared/path.rb
deleted file mode 100644
index 494dcca775..0000000000
--- a/spec/ruby/core/dir/shared/path.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../fixtures/common'
-require_relative 'closed'
-
-describe :dir_path, shared: true do
-  it "returns the path that was supplied to .new or .open" do
-    dir = Dir.open DirSpecs.mock_dir
-    begin
-      dir.send(@method).should == DirSpecs.mock_dir
-    ensure
-      dir.close rescue nil
-    end
-  end
-
-  it "returns the path even when called on a closed Dir instance" do
-    dir = Dir.open DirSpecs.mock_dir
-    dir.close
-    dir.send(@method).should == DirSpecs.mock_dir
-  end
-
-  it "returns a String with the same encoding as the argument to .open" do
-    path = DirSpecs.mock_dir.force_encoding Encoding::IBM866
-    dir = Dir.open path
-    begin
-      dir.send(@method).encoding.should equal(Encoding::IBM866)
-    ensure
-      dir.close
-    end
-  end
-end
diff --git a/spec/ruby/core/dir/shared/pos.rb b/spec/ruby/core/dir/shared/pos.rb
index 2165932d99..741de8918c 100644
--- a/spec/ruby/core/dir/shared/pos.rb
+++ b/spec/ruby/core/dir/shared/pos.rb
@@ -1,30 +1,3 @@
-describe :dir_pos, shared: true do
-  before :each do
-    @dir = Dir.open DirSpecs.mock_dir
-  end
-
-  after :each do
-    @dir.close rescue nil
-  end
-
-  it "returns an Integer representing the current position in the directory" do
-    @dir.send(@method).should be_kind_of(Integer)
-    @dir.send(@method).should be_kind_of(Integer)
-    @dir.send(@method).should be_kind_of(Integer)
-  end
-
-  it "returns a different Integer if moved from previous position" do
-    a = @dir.send(@method)
-    @dir.read
-    b = @dir.send(@method)
-
-    a.should be_kind_of(Integer)
-    b.should be_kind_of(Integer)
-
-    a.should_not == b
-  end
-end
-
 describe :dir_pos_set, shared: true do
   before :each do
     @dir = Dir.open DirSpecs.mock_dir
diff --git a/spec/ruby/core/dir/shared/pwd.rb b/spec/ruby/core/dir/shared/pwd.rb
deleted file mode 100644
index 2a8d7fe790..0000000000
--- a/spec/ruby/core/dir/shared/pwd.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-describe :dir_pwd, shared: true do
-  before :each do
-    @fs_encoding = Encoding.find('filesystem')
-  end
-
-  it "returns the current working directory" do
-    pwd = Dir.send(@method)
-
-    File.directory?(pwd).should == true
-
-    # On ubuntu gutsy, for example, /bin/pwd does not
-    # understand -P. With just `pwd -P`, /bin/pwd is run.
-
-    # The following uses inode rather than file names to account for
-    # case insensitive file systems like default OS/X file systems
-    platform_is_not :windows do
-      File.stat(pwd).ino.should == File.stat(`/bin/sh -c "pwd -P"`.chomp).ino
-    end
-    platform_is :windows do
-      File.stat(pwd).ino.should == File.stat(File.expand_path(`cd`.chomp)).ino
-    end
-  end
-
-  it "returns an absolute path" do
-    pwd = Dir.send(@method)
-    pwd.should == File.expand_path(pwd)
-  end
-
-  it "returns an absolute path even when chdir to a relative path" do
-    Dir.chdir(".") do
-      pwd = Dir.send(@method)
-      File.directory?(pwd).should == true
-      pwd.should == File.expand_path(pwd)
-    end
-  end
-
-  it "returns a String with the filesystem encoding" do
-    enc = Dir.send(@method).encoding
-    if @fs_encoding == Encoding::US_ASCII
-      [Encoding::US_ASCII, Encoding::BINARY].should include(enc)
-    else
-      enc.should equal(@fs_encoding)
-    end
-  end
-end
diff --git a/spec/ruby/core/dir/tell_spec.rb b/spec/ruby/core/dir/tell_spec.rb
index af86dc1598..dcbb40438f 100644
--- a/spec/ruby/core/dir/tell_spec.rb
+++ b/spec/ruby/core/dir/tell_spec.rb
@@ -12,7 +12,30 @@ describe "Dir#tell" do
     DirSpecs.delete_mock_dirs
   end
 
-  it_behaves_like :dir_pos, :tell
-
   it_behaves_like :dir_closed, :tell
+
+  before :each do
+    @dir = Dir.open DirSpecs.mock_dir
+  end
+
+  after :each do
+    @dir.close rescue nil
+  end
+
+  it "returns an Integer representing the current position in the directory" do
+    @dir.tell.should.is_a?(Integer)
+    @dir.tell.should.is_a?(Integer)
+    @dir.tell.should.is_a?(Integer)
+  end
+
+  it "returns a different Integer if moved from previous position" do
+    a = @dir.tell
+    @dir.read
+    b = @dir.tell
+
+    a.should.is_a?(Integer)
+    b.should.is_a?(Integer)
+
+    a.should_not == b
+  end
 end
diff --git a/spec/ruby/core/dir/to_path_spec.rb b/spec/ruby/core/dir/to_path_spec.rb
index 77404a3dc8..2ed533e757 100644
--- a/spec/ruby/core/dir/to_path_spec.rb
+++ b/spec/ruby/core/dir/to_path_spec.rb
@@ -1,15 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/common'
-require_relative 'shared/path'
 
 describe "Dir#to_path" do
-  before :all do
-    DirSpecs.create_mock_dirs
+  it "is an alias of Dir#path" do
+    Dir.instance_method(:to_path).should == Dir.instance_method(:path)
   end
-
-  after :all do
-    DirSpecs.delete_mock_dirs
-  end
-
-  it_behaves_like :dir_path, :to_path
 end
diff --git a/spec/ruby/core/encoding/aliases_spec.rb b/spec/ruby/core/encoding/aliases_spec.rb
index 786157981a..12c6c6cf85 100644
--- a/spec/ruby/core/encoding/aliases_spec.rb
+++ b/spec/ruby/core/encoding/aliases_spec.rb
@@ -2,24 +2,24 @@ require_relative '../../spec_helper'
 
 describe "Encoding.aliases" do
   it "returns a Hash" do
-    Encoding.aliases.should be_an_instance_of(Hash)
+    Encoding.aliases.should.instance_of?(Hash)
   end
 
   it "has Strings as keys" do
     Encoding.aliases.keys.each do |key|
-      key.should be_an_instance_of(String)
+      key.should.instance_of?(String)
     end
   end
 
   it "has Strings as values" do
     Encoding.aliases.values.each do |value|
-      value.should be_an_instance_of(String)
+      value.should.instance_of?(String)
     end
   end
 
   it "has alias names as its keys" do
-    Encoding.aliases.key?('BINARY').should be_true
-    Encoding.aliases.key?('ASCII').should be_true
+    Encoding.aliases.key?('BINARY').should == true
+    Encoding.aliases.key?('ASCII').should == true
   end
 
   it "has the names of the aliased encoding as its values" do
diff --git a/spec/ruby/core/encoding/ascii_compatible_spec.rb b/spec/ruby/core/encoding/ascii_compatible_spec.rb
index 4804300e85..04fc159bb8 100644
--- a/spec/ruby/core/encoding/ascii_compatible_spec.rb
+++ b/spec/ruby/core/encoding/ascii_compatible_spec.rb
@@ -2,10 +2,21 @@ require_relative '../../spec_helper'
 
 describe "Encoding#ascii_compatible?" do
   it "returns true if self represents an ASCII-compatible encoding" do
-    Encoding::UTF_8.ascii_compatible?.should be_true
+    Encoding::UTF_8.ascii_compatible?.should == true
   end
 
   it "returns false if self does not represent an ASCII-compatible encoding" do
-    Encoding::UTF_16LE.ascii_compatible?.should be_false
+    Encoding::UTF_16LE.ascii_compatible?.should == false
+  end
+
+  it "returns false for UTF_16 and UTF_32" do
+    Encoding::UTF_16.should_not.ascii_compatible?
+    Encoding::UTF_32.should_not.ascii_compatible?
+  end
+
+  it "is always false for dummy encodings" do
+    Encoding.list.select(&:dummy?).each do |encoding|
+      encoding.should_not.ascii_compatible?
+    end
   end
 end
diff --git a/spec/ruby/core/encoding/compatible_spec.rb b/spec/ruby/core/encoding/compatible_spec.rb
index dc47a6553a..0d620e5bf3 100644
--- a/spec/ruby/core/encoding/compatible_spec.rb
+++ b/spec/ruby/core/encoding/compatible_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require_relative '../../spec_helper'
 
@@ -7,7 +7,7 @@ require_relative '../../spec_helper'
 describe "Encoding.compatible? String, String" do
   describe "when the first's Encoding is valid US-ASCII" do
     before :each do
-      @str = "abc".force_encoding Encoding::US_ASCII
+      @str = "abc".dup.force_encoding Encoding::US_ASCII
     end
 
     it "returns US-ASCII when the second's is US-ASCII" do
@@ -33,29 +33,29 @@ describe "Encoding.compatible? String, String" do
 
   describe "when the first's Encoding is ASCII compatible and ASCII only" do
     it "returns the first's Encoding if the second is ASCII compatible and ASCII only" do
-      [ [Encoding, "abc".force_encoding("UTF-8"), "123".force_encoding("Shift_JIS"), Encoding::UTF_8],
-        [Encoding, "123".force_encoding("Shift_JIS"), "abc".force_encoding("UTF-8"), Encoding::Shift_JIS]
+      [ [Encoding, "abc".dup.force_encoding("UTF-8"), "123".dup.force_encoding("Shift_JIS"), Encoding::UTF_8],
+        [Encoding, "123".dup.force_encoding("Shift_JIS"), "abc".dup.force_encoding("UTF-8"), Encoding::Shift_JIS]
       ].should be_computed_by(:compatible?)
     end
 
     it "returns the first's Encoding if the second is ASCII compatible and ASCII only" do
-      [ [Encoding, "abc".force_encoding("BINARY"), "123".force_encoding("US-ASCII"), Encoding::BINARY],
-        [Encoding, "123".force_encoding("US-ASCII"), "abc".force_encoding("BINARY"), Encoding::US_ASCII]
+      [ [Encoding, "abc".dup.force_encoding("BINARY"), "123".dup.force_encoding("US-ASCII"), Encoding::BINARY],
+        [Encoding, "123".dup.force_encoding("US-ASCII"), "abc".dup.force_encoding("BINARY"), Encoding::US_ASCII]
       ].should be_computed_by(:compatible?)
     end
 
     it "returns the second's Encoding if the second is ASCII compatible but not ASCII only" do
-      [ [Encoding, "abc".force_encoding("UTF-8"), "\xff".force_encoding("Shift_JIS"), Encoding::Shift_JIS],
-        [Encoding, "123".force_encoding("Shift_JIS"), "\xff".force_encoding("UTF-8"), Encoding::UTF_8],
-        [Encoding, "abc".force_encoding("BINARY"), "\xff".force_encoding("US-ASCII"), Encoding::US_ASCII],
-        [Encoding, "123".force_encoding("US-ASCII"), "\xff".force_encoding("BINARY"), Encoding::BINARY],
+      [ [Encoding, "abc".dup.force_encoding("UTF-8"), "\xff".dup.force_encoding("Shift_JIS"), Encoding::Shift_JIS],
+        [Encoding, "123".dup.force_encoding("Shift_JIS"), "\xff".dup.force_encoding("UTF-8"), Encoding::UTF_8],
+        [Encoding, "abc".dup.force_encoding("BINARY"), "\xff".dup.force_encoding("US-ASCII"), Encoding::US_ASCII],
+        [Encoding, "123".dup.force_encoding("US-ASCII"), "\xff".dup.force_encoding("BINARY"), Encoding::BINARY],
       ].should be_computed_by(:compatible?)
     end
 
     it "returns nil if the second's Encoding is not ASCII compatible" do
-      a = "abc".force_encoding("UTF-8")
-      b = "123".force_encoding("UTF-16LE")
-      Encoding.compatible?(a, b).should be_nil
+      a = "abc".dup.force_encoding("UTF-8")
+      b = "1234".dup.force_encoding("UTF-16LE")
+      Encoding.compatible?(a, b).should == nil
     end
   end
 
@@ -69,36 +69,36 @@ describe "Encoding.compatible? String, String" do
     end
 
     it "returns nil if the second encoding is ASCII compatible but neither String's encoding is ASCII only" do
-      Encoding.compatible?("\xff", "\u3042".encode("utf-8")).should be_nil
+      Encoding.compatible?("\xff", "\u3042".encode("utf-8")).should == nil
     end
   end
 
   describe "when the first's Encoding is not ASCII compatible" do
     before :each do
-      @str = "abc".force_encoding Encoding::UTF_7
+      @str = "abc".dup.force_encoding Encoding::UTF_7
     end
 
     it "returns nil when the second String is US-ASCII" do
-      Encoding.compatible?(@str, "def".encode("us-ascii")).should be_nil
+      Encoding.compatible?(@str, "def".encode("us-ascii")).should == nil
     end
 
     it "returns nil when the second String is BINARY and ASCII only" do
-      Encoding.compatible?(@str, "\x7f").should be_nil
+      Encoding.compatible?(@str, "\x7f").should == nil
     end
 
     it "returns nil when the second String is BINARY but not ASCII only" do
-      Encoding.compatible?(@str, "\xff").should be_nil
+      Encoding.compatible?(@str, "\xff").should == nil
     end
 
     it "returns the Encoding when the second's Encoding is not ASCII compatible but the same as the first's Encoding" do
-      encoding = Encoding.compatible?(@str, "def".force_encoding("utf-7"))
+      encoding = Encoding.compatible?(@str, "def".dup.force_encoding("utf-7"))
       encoding.should == Encoding::UTF_7
     end
   end
 
   describe "when the first's Encoding is invalid" do
     before :each do
-      @str = "\xff".force_encoding Encoding::UTF_8
+      @str = "\xff".dup.force_encoding Encoding::UTF_8
     end
 
     it "returns the first's Encoding when the second's Encoding is US-ASCII" do
@@ -110,15 +110,15 @@ describe "Encoding.compatible? String, String" do
     end
 
     it "returns nil when the second's Encoding is BINARY but not ASCII only" do
-      Encoding.compatible?(@str, "\xff").should be_nil
+      Encoding.compatible?(@str, "\xff").should == nil
     end
 
     it "returns nil when the second's Encoding is invalid and ASCII only" do
-      Encoding.compatible?(@str, "\x7f".force_encoding("utf-16be")).should be_nil
+      Encoding.compatible?(@str, "\x7f\x7f".dup.force_encoding("utf-16be")).should == nil
     end
 
     it "returns nil when the second's Encoding is invalid and not ASCII only" do
-      Encoding.compatible?(@str, "\xff".force_encoding("utf-16be")).should be_nil
+      Encoding.compatible?(@str, "\xff\xff".dup.force_encoding("utf-16be")).should == nil
     end
 
     it "returns the Encoding when the second's Encoding is invalid but the same as the first" do
@@ -129,7 +129,7 @@ describe "Encoding.compatible? String, String" do
   describe "when the first String is empty and the second is not" do
     describe "and the first's Encoding is ASCII compatible" do
       before :each do
-        @str = "".force_encoding("utf-8")
+        @str = "".dup.force_encoding("utf-8")
       end
 
       it "returns the first's encoding when the second String is ASCII only" do
@@ -143,7 +143,7 @@ describe "Encoding.compatible? String, String" do
 
     describe "when the first's Encoding is not ASCII compatible" do
       before :each do
-        @str = "".force_encoding Encoding::UTF_7
+        @str = "".dup.force_encoding Encoding::UTF_7
       end
 
       it "returns the second string's encoding" do
@@ -154,18 +154,391 @@ describe "Encoding.compatible? String, String" do
 
   describe "when the second String is empty" do
     before :each do
-      @str = "abc".force_encoding("utf-7")
+      @str = "abc".dup.force_encoding("utf-7")
     end
 
     it "returns the first Encoding" do
       Encoding.compatible?(@str, "").should == Encoding::UTF_7
     end
   end
+
+  # Encoding negotiation depends on whether encodings are ASCII-compatible, empty
+  # and contain only ASCII characters (that take 7 bits). Check US-ASCII, UTF-8 and
+  # BINARY encodings (as most common) as well as an ASCII-compatible, a non-ASCII-compatible and a dummy
+  # encodings in all possible combinations.
+  describe "compatibility matrix" do
+
+#     Use the following script to regenerate the matrix:
+#
+#     ```
+#       # encoding: binary
+#
+#       ENCODINGS = [
+#         "US-ASCII",
+#         "UTF-8",
+#         "ASCII-8BIT",
+#         "ISO-8859-1",  # ASCII-compatible
+#         "UTF-16BE",    # non-ASCII-compatible
+#         "ISO-2022-JP"  # dummy
+#       ]
+#
+#       TYPES = [:empty, :"7bits", :non7bits]
+#
+#       VALUES = {
+#         empty: "",
+#         :"7bits" => "\x01\x01",
+#         non7bits: "\x01\x81"
+#       }
+#
+#       ENCODINGS.product(TYPES, ENCODINGS, TYPES).each do |encoding1, type1, encoding2, type2|
+#         value1 = VALUES[type1].dup.force_encoding(encoding1)
+#         value2 = VALUES[type2].dup.force_encoding(encoding2)
+#
+#         result_encoding = Encoding.compatible?(value1, value2)
+#
+#         puts "[#{encoding1.inspect}, #{value1.inspect}, #{encoding2.inspect}, #{value2.inspect}, #{result_encoding&.name.inspect}],"
+#       end
+#     ```
+
+    matrix = [
+      ["US-ASCII", "", "US-ASCII", "", "US-ASCII"],
+      ["US-ASCII", "", "US-ASCII", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["US-ASCII", "", "UTF-8", "", "US-ASCII"],
+      ["US-ASCII", "", "UTF-8", "\u0001\u0001", "US-ASCII"],
+      ["US-ASCII", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["US-ASCII", "", "ASCII-8BIT", "", "US-ASCII"],
+      ["US-ASCII", "", "ASCII-8BIT", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["US-ASCII", "", "ISO-8859-1", "", "US-ASCII"],
+      ["US-ASCII", "", "ISO-8859-1", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["US-ASCII", "", "UTF-16BE", "", "US-ASCII"],
+      ["US-ASCII", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["US-ASCII", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["US-ASCII", "", "ISO-2022-JP", "", "US-ASCII"],
+      ["US-ASCII", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["US-ASCII", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["US-ASCII", "\x01\x01", "US-ASCII", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "US-ASCII", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "UTF-8", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "UTF-8", "\u0001\u0001", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["US-ASCII", "\x01\x01", "ASCII-8BIT", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "ASCII-8BIT", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["US-ASCII", "\x01\x01", "ISO-8859-1", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "ISO-8859-1", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["US-ASCII", "\x01\x01", "UTF-16BE", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "UTF-16BE", "\u0101", nil],
+      ["US-ASCII", "\x01\x01", "UTF-16BE", "\u0181", nil],
+      ["US-ASCII", "\x01\x01", "ISO-2022-JP", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x01", "ISO-2022-JP", "\x01\x01", nil],
+      ["US-ASCII", "\x01\x01", "ISO-2022-JP", "\x01\x81", nil],
+      ["US-ASCII", "\x01\x81", "US-ASCII", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "US-ASCII", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "UTF-8", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "UTF-8", "\u0001\u0001", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "UTF-8", "\u0001\x81", nil],
+      ["US-ASCII", "\x01\x81", "ASCII-8BIT", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "ASCII-8BIT", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "ASCII-8BIT", "\x01\x81", nil],
+      ["US-ASCII", "\x01\x81", "ISO-8859-1", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "ISO-8859-1", "\x01\x01", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "ISO-8859-1", "\x01\x81", nil],
+      ["US-ASCII", "\x01\x81", "UTF-16BE", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "UTF-16BE", "\u0101", nil],
+      ["US-ASCII", "\x01\x81", "UTF-16BE", "\u0181", nil],
+      ["US-ASCII", "\x01\x81", "ISO-2022-JP", "", "US-ASCII"],
+      ["US-ASCII", "\x01\x81", "ISO-2022-JP", "\x01\x01", nil],
+      ["US-ASCII", "\x01\x81", "ISO-2022-JP", "\x01\x81", nil],
+      ["UTF-8", "", "US-ASCII", "", "UTF-8"],
+      ["UTF-8", "", "US-ASCII", "\x01\x01", "UTF-8"],
+      ["UTF-8", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["UTF-8", "", "UTF-8", "", "UTF-8"],
+      ["UTF-8", "", "UTF-8", "\u0001\u0001", "UTF-8"],
+      ["UTF-8", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["UTF-8", "", "ASCII-8BIT", "", "UTF-8"],
+      ["UTF-8", "", "ASCII-8BIT", "\x01\x01", "UTF-8"],
+      ["UTF-8", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["UTF-8", "", "ISO-8859-1", "", "UTF-8"],
+      ["UTF-8", "", "ISO-8859-1", "\x01\x01", "UTF-8"],
+      ["UTF-8", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["UTF-8", "", "UTF-16BE", "", "UTF-8"],
+      ["UTF-8", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["UTF-8", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["UTF-8", "", "ISO-2022-JP", "", "UTF-8"],
+      ["UTF-8", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["UTF-8", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["UTF-8", "\u0001\u0001", "US-ASCII", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "US-ASCII", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["UTF-8", "\u0001\u0001", "UTF-8", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "UTF-8", "\u0001\u0001", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ASCII-8BIT", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ASCII-8BIT", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["UTF-8", "\u0001\u0001", "ISO-8859-1", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ISO-8859-1", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["UTF-8", "\u0001\u0001", "UTF-16BE", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "UTF-16BE", "\u0101", nil],
+      ["UTF-8", "\u0001\u0001", "UTF-16BE", "\u0181", nil],
+      ["UTF-8", "\u0001\u0001", "ISO-2022-JP", "", "UTF-8"],
+      ["UTF-8", "\u0001\u0001", "ISO-2022-JP", "\x01\x01", nil],
+      ["UTF-8", "\u0001\u0001", "ISO-2022-JP", "\x01\x81", nil],
+      ["UTF-8", "\u0001\x81", "US-ASCII", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "US-ASCII", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "US-ASCII", "\x01\x81", nil],
+      ["UTF-8", "\u0001\x81", "UTF-8", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "UTF-8", "\u0001\u0001", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ASCII-8BIT", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ASCII-8BIT", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ASCII-8BIT", "\x01\x81", nil],
+      ["UTF-8", "\u0001\x81", "ISO-8859-1", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ISO-8859-1", "\x01\x01", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ISO-8859-1", "\x01\x81", nil],
+      ["UTF-8", "\u0001\x81", "UTF-16BE", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "UTF-16BE", "\u0101", nil],
+      ["UTF-8", "\u0001\x81", "UTF-16BE", "\u0181", nil],
+      ["UTF-8", "\u0001\x81", "ISO-2022-JP", "", "UTF-8"],
+      ["UTF-8", "\u0001\x81", "ISO-2022-JP", "\x01\x01", nil],
+      ["UTF-8", "\u0001\x81", "ISO-2022-JP", "\x01\x81", nil],
+      ["ASCII-8BIT", "", "US-ASCII", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "US-ASCII", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["ASCII-8BIT", "", "UTF-8", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "UTF-8", "\u0001\u0001", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["ASCII-8BIT", "", "ASCII-8BIT", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ASCII-8BIT", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ISO-8859-1", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ISO-8859-1", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ASCII-8BIT", "", "UTF-16BE", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["ASCII-8BIT", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["ASCII-8BIT", "", "ISO-2022-JP", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["ASCII-8BIT", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["ASCII-8BIT", "\x01\x01", "US-ASCII", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "US-ASCII", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["ASCII-8BIT", "\x01\x01", "UTF-8", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "UTF-8", "\u0001\u0001", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["ASCII-8BIT", "\x01\x01", "ASCII-8BIT", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ASCII-8BIT", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ISO-8859-1", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ISO-8859-1", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ASCII-8BIT", "\x01\x01", "UTF-16BE", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "UTF-16BE", "\u0101", nil],
+      ["ASCII-8BIT", "\x01\x01", "UTF-16BE", "\u0181", nil],
+      ["ASCII-8BIT", "\x01\x01", "ISO-2022-JP", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x01", "ISO-2022-JP", "\x01\x01", nil],
+      ["ASCII-8BIT", "\x01\x01", "ISO-2022-JP", "\x01\x81", nil],
+      ["ASCII-8BIT", "\x01\x81", "US-ASCII", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "US-ASCII", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "US-ASCII", "\x01\x81", nil],
+      ["ASCII-8BIT", "\x01\x81", "UTF-8", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "UTF-8", "\u0001\u0001", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "UTF-8", "\u0001\x81", nil],
+      ["ASCII-8BIT", "\x01\x81", "ASCII-8BIT", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ASCII-8BIT", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ISO-8859-1", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ISO-8859-1", "\x01\x01", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ISO-8859-1", "\x01\x81", nil],
+      ["ASCII-8BIT", "\x01\x81", "UTF-16BE", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "UTF-16BE", "\u0101", nil],
+      ["ASCII-8BIT", "\x01\x81", "UTF-16BE", "\u0181", nil],
+      ["ASCII-8BIT", "\x01\x81", "ISO-2022-JP", "", "ASCII-8BIT"],
+      ["ASCII-8BIT", "\x01\x81", "ISO-2022-JP", "\x01\x01", nil],
+      ["ASCII-8BIT", "\x01\x81", "ISO-2022-JP", "\x01\x81", nil],
+      ["ISO-8859-1", "", "US-ASCII", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "US-ASCII", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["ISO-8859-1", "", "UTF-8", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "UTF-8", "\u0001\u0001", "ISO-8859-1"],
+      ["ISO-8859-1", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["ISO-8859-1", "", "ASCII-8BIT", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "ASCII-8BIT", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ISO-8859-1", "", "ISO-8859-1", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "ISO-8859-1", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ISO-8859-1", "", "UTF-16BE", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["ISO-8859-1", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["ISO-8859-1", "", "ISO-2022-JP", "", "ISO-8859-1"],
+      ["ISO-8859-1", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["ISO-8859-1", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["ISO-8859-1", "\x01\x01", "US-ASCII", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "US-ASCII", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["ISO-8859-1", "\x01\x01", "UTF-8", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "UTF-8", "\u0001\u0001", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["ISO-8859-1", "\x01\x01", "ASCII-8BIT", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "ASCII-8BIT", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ISO-8859-1", "\x01\x01", "ISO-8859-1", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "ISO-8859-1", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "UTF-16BE", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "UTF-16BE", "\u0101", nil],
+      ["ISO-8859-1", "\x01\x01", "UTF-16BE", "\u0181", nil],
+      ["ISO-8859-1", "\x01\x01", "ISO-2022-JP", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x01", "ISO-2022-JP", "\x01\x01", nil],
+      ["ISO-8859-1", "\x01\x01", "ISO-2022-JP", "\x01\x81", nil],
+      ["ISO-8859-1", "\x01\x81", "US-ASCII", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "US-ASCII", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "US-ASCII", "\x01\x81", nil],
+      ["ISO-8859-1", "\x01\x81", "UTF-8", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "UTF-8", "\u0001\u0001", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "UTF-8", "\u0001\x81", nil],
+      ["ISO-8859-1", "\x01\x81", "ASCII-8BIT", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "ASCII-8BIT", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "ASCII-8BIT", "\x01\x81", nil],
+      ["ISO-8859-1", "\x01\x81", "ISO-8859-1", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "ISO-8859-1", "\x01\x01", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "UTF-16BE", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "UTF-16BE", "\u0101", nil],
+      ["ISO-8859-1", "\x01\x81", "UTF-16BE", "\u0181", nil],
+      ["ISO-8859-1", "\x01\x81", "ISO-2022-JP", "", "ISO-8859-1"],
+      ["ISO-8859-1", "\x01\x81", "ISO-2022-JP", "\x01\x01", nil],
+      ["ISO-8859-1", "\x01\x81", "ISO-2022-JP", "\x01\x81", nil],
+      ["UTF-16BE", "", "US-ASCII", "", "UTF-16BE"],
+      ["UTF-16BE", "", "US-ASCII", "\x01\x01", "US-ASCII"],
+      ["UTF-16BE", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["UTF-16BE", "", "UTF-8", "", "UTF-16BE"],
+      ["UTF-16BE", "", "UTF-8", "\u0001\u0001", "UTF-8"],
+      ["UTF-16BE", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["UTF-16BE", "", "ASCII-8BIT", "", "UTF-16BE"],
+      ["UTF-16BE", "", "ASCII-8BIT", "\x01\x01", "ASCII-8BIT"],
+      ["UTF-16BE", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["UTF-16BE", "", "ISO-8859-1", "", "UTF-16BE"],
+      ["UTF-16BE", "", "ISO-8859-1", "\x01\x01", "ISO-8859-1"],
+      ["UTF-16BE", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["UTF-16BE", "", "UTF-16BE", "", "UTF-16BE"],
+      ["UTF-16BE", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["UTF-16BE", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["UTF-16BE", "", "ISO-2022-JP", "", "UTF-16BE"],
+      ["UTF-16BE", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["UTF-16BE", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["UTF-16BE", "\u0101", "US-ASCII", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "US-ASCII", "\x01\x01", nil],
+      ["UTF-16BE", "\u0101", "US-ASCII", "\x01\x81", nil],
+      ["UTF-16BE", "\u0101", "UTF-8", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "UTF-8", "\u0001\u0001", nil],
+      ["UTF-16BE", "\u0101", "UTF-8", "\u0001\x81", nil],
+      ["UTF-16BE", "\u0101", "ASCII-8BIT", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "ASCII-8BIT", "\x01\x01", nil],
+      ["UTF-16BE", "\u0101", "ASCII-8BIT", "\x01\x81", nil],
+      ["UTF-16BE", "\u0101", "ISO-8859-1", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "ISO-8859-1", "\x01\x01", nil],
+      ["UTF-16BE", "\u0101", "ISO-8859-1", "\x01\x81", nil],
+      ["UTF-16BE", "\u0101", "UTF-16BE", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "ISO-2022-JP", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0101", "ISO-2022-JP", "\x01\x01", nil],
+      ["UTF-16BE", "\u0101", "ISO-2022-JP", "\x01\x81", nil],
+      ["UTF-16BE", "\u0181", "US-ASCII", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "US-ASCII", "\x01\x01", nil],
+      ["UTF-16BE", "\u0181", "US-ASCII", "\x01\x81", nil],
+      ["UTF-16BE", "\u0181", "UTF-8", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "UTF-8", "\u0001\u0001", nil],
+      ["UTF-16BE", "\u0181", "UTF-8", "\u0001\x81", nil],
+      ["UTF-16BE", "\u0181", "ASCII-8BIT", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "ASCII-8BIT", "\x01\x01", nil],
+      ["UTF-16BE", "\u0181", "ASCII-8BIT", "\x01\x81", nil],
+      ["UTF-16BE", "\u0181", "ISO-8859-1", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "ISO-8859-1", "\x01\x01", nil],
+      ["UTF-16BE", "\u0181", "ISO-8859-1", "\x01\x81", nil],
+      ["UTF-16BE", "\u0181", "UTF-16BE", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "ISO-2022-JP", "", "UTF-16BE"],
+      ["UTF-16BE", "\u0181", "ISO-2022-JP", "\x01\x01", nil],
+      ["UTF-16BE", "\u0181", "ISO-2022-JP", "\x01\x81", nil],
+      ["ISO-2022-JP", "", "US-ASCII", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "US-ASCII", "\x01\x01", "US-ASCII"],
+      ["ISO-2022-JP", "", "US-ASCII", "\x01\x81", "US-ASCII"],
+      ["ISO-2022-JP", "", "UTF-8", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "UTF-8", "\u0001\u0001", "UTF-8"],
+      ["ISO-2022-JP", "", "UTF-8", "\u0001\x81", "UTF-8"],
+      ["ISO-2022-JP", "", "ASCII-8BIT", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "ASCII-8BIT", "\x01\x01", "ASCII-8BIT"],
+      ["ISO-2022-JP", "", "ASCII-8BIT", "\x01\x81", "ASCII-8BIT"],
+      ["ISO-2022-JP", "", "ISO-8859-1", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "ISO-8859-1", "\x01\x01", "ISO-8859-1"],
+      ["ISO-2022-JP", "", "ISO-8859-1", "\x01\x81", "ISO-8859-1"],
+      ["ISO-2022-JP", "", "UTF-16BE", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "UTF-16BE", "\u0101", "UTF-16BE"],
+      ["ISO-2022-JP", "", "UTF-16BE", "\u0181", "UTF-16BE"],
+      ["ISO-2022-JP", "", "ISO-2022-JP", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["ISO-2022-JP", "", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "US-ASCII", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "US-ASCII", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x01", "US-ASCII", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x01", "UTF-8", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "UTF-8", "\u0001\u0001", nil],
+      ["ISO-2022-JP", "\x01\x01", "UTF-8", "\u0001\x81", nil],
+      ["ISO-2022-JP", "\x01\x01", "ASCII-8BIT", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "ASCII-8BIT", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x01", "ASCII-8BIT", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x01", "ISO-8859-1", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "ISO-8859-1", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x01", "ISO-8859-1", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x01", "UTF-16BE", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "UTF-16BE", "\u0101", nil],
+      ["ISO-2022-JP", "\x01\x01", "UTF-16BE", "\u0181", nil],
+      ["ISO-2022-JP", "\x01\x01", "ISO-2022-JP", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x01", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "US-ASCII", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "US-ASCII", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x81", "US-ASCII", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x81", "UTF-8", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "UTF-8", "\u0001\u0001", nil],
+      ["ISO-2022-JP", "\x01\x81", "UTF-8", "\u0001\x81", nil],
+      ["ISO-2022-JP", "\x01\x81", "ASCII-8BIT", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "ASCII-8BIT", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x81", "ASCII-8BIT", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x81", "ISO-8859-1", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "ISO-8859-1", "\x01\x01", nil],
+      ["ISO-2022-JP", "\x01\x81", "ISO-8859-1", "\x01\x81", nil],
+      ["ISO-2022-JP", "\x01\x81", "UTF-16BE", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "UTF-16BE", "\u0101", nil],
+      ["ISO-2022-JP", "\x01\x81", "UTF-16BE", "\u0181", nil],
+      ["ISO-2022-JP", "\x01\x81", "ISO-2022-JP", "", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "ISO-2022-JP", "\x01\x01", "ISO-2022-JP"],
+      ["ISO-2022-JP", "\x01\x81", "ISO-2022-JP", "\x01\x81", "ISO-2022-JP"],
+    ]
+
+    matrix.each do |encoding1, value1, encoding2, value2, compatible_encoding|
+      it "returns #{compatible_encoding} for #{value1.inspect} in #{encoding1} and #{value2.inspect} in #{encoding2}" do
+        actual_encoding = Encoding.compatible?(value1.dup.force_encoding(encoding1), value2.dup.force_encoding(encoding2))
+        actual_encoding&.name.should == compatible_encoding
+      end
+    end
+  end
 end
 
 describe "Encoding.compatible? String, Regexp" do
   it "returns US-ASCII if both are US-ASCII" do
-    str = "abc".force_encoding("us-ascii")
+    str = "abc".dup.force_encoding("us-ascii")
     Encoding.compatible?(str, /abc/).should == Encoding::US_ASCII
   end
 
@@ -180,15 +553,20 @@ describe "Encoding.compatible? String, Regexp" do
   it "returns the String's Encoding if the String is not ASCII only" do
     [ [Encoding, "\xff",                                  Encoding::BINARY],
       [Encoding, "\u3042".encode("utf-8"),                Encoding::UTF_8],
-      [Encoding, "\xa4\xa2".force_encoding("euc-jp"),     Encoding::EUC_JP],
-      [Encoding, "\x82\xa0".force_encoding("shift_jis"),  Encoding::Shift_JIS],
+      [Encoding, "\xa4\xa2".dup.force_encoding("euc-jp"),     Encoding::EUC_JP],
+      [Encoding, "\x82\xa0".dup.force_encoding("shift_jis"),  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, /abc/)
   end
+
+  it "returns the Regexp's Encoding if the String is ASCII only and the Regexp is not" do
+    r = Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp"))
+    Encoding.compatible?("hello".dup.force_encoding("utf-8"), r).should == Encoding::EUC_JP
+  end
 end
 
 describe "Encoding.compatible? String, Symbol" do
   it "returns US-ASCII if both are ASCII only" do
-    str = "abc".force_encoding("us-ascii")
+    str = "abc".dup.force_encoding("us-ascii")
     Encoding.compatible?(str, :abc).should == Encoding::US_ASCII
   end
 
@@ -203,26 +581,26 @@ describe "Encoding.compatible? String, Symbol" do
   it "returns the String's Encoding if the String is not ASCII only" do
     [ [Encoding, "\xff",                                  Encoding::BINARY],
       [Encoding, "\u3042".encode("utf-8"),                Encoding::UTF_8],
-      [Encoding, "\xa4\xa2".force_encoding("euc-jp"),     Encoding::EUC_JP],
-      [Encoding, "\x82\xa0".force_encoding("shift_jis"),  Encoding::Shift_JIS],
+      [Encoding, "\xa4\xa2".dup.force_encoding("euc-jp"),     Encoding::EUC_JP],
+      [Encoding, "\x82\xa0".dup.force_encoding("shift_jis"),  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, :abc)
   end
 end
 
 describe "Encoding.compatible? String, Encoding" do
   it "returns nil if the String's encoding is not ASCII compatible" do
-    Encoding.compatible?("abc".encode("utf-32le"), Encoding::US_ASCII).should be_nil
+    Encoding.compatible?("abc".encode("utf-32le"), Encoding::US_ASCII).should == nil
   end
 
   it "returns nil if the Encoding is not ASCII compatible" do
-    Encoding.compatible?("abc".encode("us-ascii"), Encoding::UTF_32LE).should be_nil
+    Encoding.compatible?("abc".encode("us-ascii"), Encoding::UTF_32LE).should == nil
   end
 
   it "returns the String's encoding if the Encoding is US-ASCII" do
     [ [Encoding, "\xff",                                  Encoding::BINARY],
       [Encoding, "\u3042".encode("utf-8"),                Encoding::UTF_8],
-      [Encoding, "\xa4\xa2".force_encoding("euc-jp"),     Encoding::EUC_JP],
-      [Encoding, "\x82\xa0".force_encoding("shift_jis"),  Encoding::Shift_JIS],
+      [Encoding, "\xa4\xa2".dup.force_encoding("euc-jp"),     Encoding::EUC_JP],
+      [Encoding, "\x82\xa0".dup.force_encoding("shift_jis"),  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, Encoding::US_ASCII)
   end
 
@@ -236,16 +614,25 @@ describe "Encoding.compatible? String, Encoding" do
   end
 
   it "returns nil if the String's encoding is ASCII compatible but the string is not ASCII only" do
-    Encoding.compatible?("\u3042".encode("utf-8"), Encoding::BINARY).should be_nil
+    Encoding.compatible?("\u3042".encode("utf-8"), Encoding::BINARY).should == nil
   end
 end
 
 describe "Encoding.compatible? Regexp, String" do
   it "returns US-ASCII if both are US-ASCII" do
-    str = "abc".force_encoding("us-ascii")
+    str = "abc".dup.force_encoding("us-ascii")
     Encoding.compatible?(/abc/, str).should == Encoding::US_ASCII
   end
 
+  it "returns the String's Encoding when the String is ASCII only with a different encoding" do
+    r = Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp"))
+    Encoding.compatible?(r, "hello".dup.force_encoding("utf-8")).should == Encoding::UTF_8
+  end
+
+  it "returns the Regexp's Encoding if the String has the same non-ASCII encoding" do
+    r = Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp"))
+    Encoding.compatible?(r, "hello".dup.force_encoding("euc-jp")).should == Encoding::EUC_JP
+  end
 end
 
 describe "Encoding.compatible? Regexp, Regexp" do
@@ -256,8 +643,8 @@ describe "Encoding.compatible? Regexp, Regexp" do
   it "returns the first's Encoding if it is not US-ASCII and not ASCII only" do
     [ [Encoding, Regexp.new("\xff"),                                  Encoding::BINARY],
       [Encoding, Regexp.new("\u3042".encode("utf-8")),                Encoding::UTF_8],
-      [Encoding, Regexp.new("\xa4\xa2".force_encoding("euc-jp")),     Encoding::EUC_JP],
-      [Encoding, Regexp.new("\x82\xa0".force_encoding("shift_jis")),  Encoding::Shift_JIS],
+      [Encoding, Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp")),     Encoding::EUC_JP],
+      [Encoding, Regexp.new("\x82\xa0".dup.force_encoding("shift_jis")),  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, /abc/)
   end
 end
@@ -270,15 +657,15 @@ describe "Encoding.compatible? Regexp, Symbol" do
   it "returns the first's Encoding if it is not US-ASCII and not ASCII only" do
     [ [Encoding, Regexp.new("\xff"),                                  Encoding::BINARY],
       [Encoding, Regexp.new("\u3042".encode("utf-8")),                Encoding::UTF_8],
-      [Encoding, Regexp.new("\xa4\xa2".force_encoding("euc-jp")),     Encoding::EUC_JP],
-      [Encoding, Regexp.new("\x82\xa0".force_encoding("shift_jis")),  Encoding::Shift_JIS],
+      [Encoding, Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp")),     Encoding::EUC_JP],
+      [Encoding, Regexp.new("\x82\xa0".dup.force_encoding("shift_jis")),  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, /abc/)
   end
 end
 
 describe "Encoding.compatible? Symbol, String" do
   it "returns US-ASCII if both are ASCII only" do
-    str = "abc".force_encoding("us-ascii")
+    str = "abc".dup.force_encoding("us-ascii")
     Encoding.compatible?(str, :abc).should == Encoding::US_ASCII
   end
 end
@@ -291,8 +678,8 @@ describe "Encoding.compatible? Symbol, Regexp" do
   it "returns the Regexp's Encoding if it is not US-ASCII and not ASCII only" do
     a = Regexp.new("\xff")
     b = Regexp.new("\u3042".encode("utf-8"))
-    c = Regexp.new("\xa4\xa2".force_encoding("euc-jp"))
-    d = Regexp.new("\x82\xa0".force_encoding("shift_jis"))
+    c = Regexp.new("\xa4\xa2".dup.force_encoding("euc-jp"))
+    d = Regexp.new("\x82\xa0".dup.force_encoding("shift_jis"))
 
     [ [Encoding, :abc, a, Encoding::BINARY],
       [Encoding, :abc, b, Encoding::UTF_8],
@@ -310,8 +697,8 @@ describe "Encoding.compatible? Symbol, Symbol" do
   it "returns the first's Encoding if it is not ASCII only" do
     [ [Encoding, "\xff".to_sym,                                  Encoding::BINARY],
       [Encoding, "\u3042".encode("utf-8").to_sym,                Encoding::UTF_8],
-      [Encoding, "\xa4\xa2".force_encoding("euc-jp").to_sym,     Encoding::EUC_JP],
-      [Encoding, "\x82\xa0".force_encoding("shift_jis").to_sym,  Encoding::Shift_JIS],
+      [Encoding, "\xa4\xa2".dup.force_encoding("euc-jp").to_sym,     Encoding::EUC_JP],
+      [Encoding, "\x82\xa0".dup.force_encoding("shift_jis").to_sym,  Encoding::Shift_JIS],
     ].should be_computed_by(:compatible?, :abc)
   end
 end
@@ -354,26 +741,32 @@ end
 
 describe "Encoding.compatible? Object, Object" do
   it "returns nil for Object, String" do
-    Encoding.compatible?(Object.new, "abc").should be_nil
+    Encoding.compatible?(Object.new, "abc").should == nil
   end
 
   it "returns nil for Object, Regexp" do
-    Encoding.compatible?(Object.new, /./).should be_nil
+    Encoding.compatible?(Object.new, /./).should == nil
   end
 
   it "returns nil for Object, Symbol" do
-    Encoding.compatible?(Object.new, :sym).should be_nil
+    Encoding.compatible?(Object.new, :sym).should == nil
   end
 
   it "returns nil for String, Object" do
-    Encoding.compatible?("abc", Object.new).should be_nil
+    Encoding.compatible?("abc", Object.new).should == nil
   end
 
   it "returns nil for Regexp, Object" do
-    Encoding.compatible?(/./, Object.new).should be_nil
+    Encoding.compatible?(/./, Object.new).should == nil
   end
 
   it "returns nil for Symbol, Object" do
-    Encoding.compatible?(:sym, Object.new).should be_nil
+    Encoding.compatible?(:sym, Object.new).should == nil
+  end
+end
+
+describe "Encoding.compatible? nil, nil" do
+  it "returns nil" do
+    Encoding.compatible?(nil, nil).should == nil
   end
 end
diff --git a/spec/ruby/core/encoding/converter/asciicompat_encoding_spec.rb b/spec/ruby/core/encoding/converter/asciicompat_encoding_spec.rb
index 1beb40af3f..07c7a88356 100644
--- a/spec/ruby/core/encoding/converter/asciicompat_encoding_spec.rb
+++ b/spec/ruby/core/encoding/converter/asciicompat_encoding_spec.rb
@@ -24,14 +24,14 @@ describe "Encoding::Converter.asciicompat_encoding" do
   end
 
   it "returns nil when the given encoding is ASCII compatible" do
-    Encoding::Converter.asciicompat_encoding('ASCII').should be_nil
-    Encoding::Converter.asciicompat_encoding('UTF-8').should be_nil
+    Encoding::Converter.asciicompat_encoding('ASCII').should == nil
+    Encoding::Converter.asciicompat_encoding('UTF-8').should == nil
   end
 
   it "handles encoding names who resolve to nil encodings" do
     internal = Encoding.default_internal
     Encoding.default_internal = nil
-    Encoding::Converter.asciicompat_encoding('internal').should be_nil
+    Encoding::Converter.asciicompat_encoding('internal').should == nil
     Encoding.default_internal = internal
   end
 end
diff --git a/spec/ruby/core/encoding/converter/constants_spec.rb b/spec/ruby/core/encoding/converter/constants_spec.rb
index 57b6a4d4e7..e2d21b5429 100644
--- a/spec/ruby/core/encoding/converter/constants_spec.rb
+++ b/spec/ruby/core/encoding/converter/constants_spec.rb
@@ -2,130 +2,130 @@ require_relative '../../../spec_helper'
 
 describe "Encoding::Converter::INVALID_MASK" do
   it "exists" do
-    Encoding::Converter.should have_constant(:INVALID_MASK)
+    Encoding::Converter.should.const_defined?(:INVALID_MASK, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::INVALID_MASK.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::INVALID_MASK.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::INVALID_REPLACE" do
   it "exists" do
-    Encoding::Converter.should have_constant(:INVALID_REPLACE)
+    Encoding::Converter.should.const_defined?(:INVALID_REPLACE, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::INVALID_REPLACE.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::INVALID_REPLACE.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::UNDEF_MASK" do
   it "exists" do
-    Encoding::Converter.should have_constant(:UNDEF_MASK)
+    Encoding::Converter.should.const_defined?(:UNDEF_MASK, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::UNDEF_MASK.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::UNDEF_MASK.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::UNDEF_REPLACE" do
   it "exists" do
-    Encoding::Converter.should have_constant(:UNDEF_REPLACE)
+    Encoding::Converter.should.const_defined?(:UNDEF_REPLACE, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::UNDEF_REPLACE.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::UNDEF_REPLACE.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::UNDEF_HEX_CHARREF" do
   it "exists" do
-    Encoding::Converter.should have_constant(:UNDEF_HEX_CHARREF)
+    Encoding::Converter.should.const_defined?(:UNDEF_HEX_CHARREF, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::UNDEF_HEX_CHARREF.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::UNDEF_HEX_CHARREF.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::PARTIAL_INPUT" do
   it "exists" do
-    Encoding::Converter.should have_constant(:PARTIAL_INPUT)
+    Encoding::Converter.should.const_defined?(:PARTIAL_INPUT, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::PARTIAL_INPUT.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::PARTIAL_INPUT.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::AFTER_OUTPUT" do
   it "exists" do
-    Encoding::Converter.should have_constant(:AFTER_OUTPUT)
+    Encoding::Converter.should.const_defined?(:AFTER_OUTPUT, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::AFTER_OUTPUT.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::AFTER_OUTPUT.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::UNIVERSAL_NEWLINE_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:UNIVERSAL_NEWLINE_DECORATOR)
+    Encoding::Converter.should.const_defined?(:UNIVERSAL_NEWLINE_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::UNIVERSAL_NEWLINE_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::UNIVERSAL_NEWLINE_DECORATOR.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::CRLF_NEWLINE_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:CRLF_NEWLINE_DECORATOR)
+    Encoding::Converter.should.const_defined?(:CRLF_NEWLINE_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::CRLF_NEWLINE_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::CRLF_NEWLINE_DECORATOR.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::CR_NEWLINE_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:CR_NEWLINE_DECORATOR)
+    Encoding::Converter.should.const_defined?(:CR_NEWLINE_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::CR_NEWLINE_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::CR_NEWLINE_DECORATOR.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::XML_TEXT_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:XML_TEXT_DECORATOR)
+    Encoding::Converter.should.const_defined?(:XML_TEXT_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::XML_TEXT_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::XML_TEXT_DECORATOR.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::XML_ATTR_CONTENT_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:XML_ATTR_CONTENT_DECORATOR)
+    Encoding::Converter.should.const_defined?(:XML_ATTR_CONTENT_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::XML_ATTR_CONTENT_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::XML_ATTR_CONTENT_DECORATOR.should.instance_of?(Integer)
   end
 end
 
 describe "Encoding::Converter::XML_ATTR_QUOTE_DECORATOR" do
   it "exists" do
-    Encoding::Converter.should have_constant(:XML_ATTR_QUOTE_DECORATOR)
+    Encoding::Converter.should.const_defined?(:XML_ATTR_QUOTE_DECORATOR, false)
   end
 
-  it "has a Fixnum value" do
-    Encoding::Converter::XML_ATTR_QUOTE_DECORATOR.should be_an_instance_of(Fixnum)
+  it "has an Integer value" do
+    Encoding::Converter::XML_ATTR_QUOTE_DECORATOR.should.instance_of?(Integer)
   end
 end
diff --git a/spec/ruby/core/encoding/converter/convert_spec.rb b/spec/ruby/core/encoding/converter/convert_spec.rb
index 95a9e0b758..c95e88a491 100644
--- a/spec/ruby/core/encoding/converter/convert_spec.rb
+++ b/spec/ruby/core/encoding/converter/convert_spec.rb
@@ -1,45 +1,45 @@
-# -*- encoding: binary -*-
+# encoding: binary
+# frozen_string_literal: true
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter#convert" do
   it "returns a String" do
     ec = Encoding::Converter.new('ascii', 'utf-8')
-    ec.convert('glark').should be_an_instance_of(String)
+    ec.convert('glark').should.instance_of?(String)
   end
 
   it "sets the encoding of the result to the target encoding" do
     ec = Encoding::Converter.new('ascii', 'utf-8')
-    str = 'glark'.force_encoding('ascii')
+    str = 'glark'.dup.force_encoding('ascii')
     ec.convert(str).encoding.should == Encoding::UTF_8
   end
 
   it "transcodes the given String to the target encoding" do
     ec = Encoding::Converter.new("utf-8", "euc-jp")
-    ec.convert("\u3042".force_encoding('UTF-8')).should == \
-      "\xA4\xA2".force_encoding('EUC-JP')
+    ec.convert("\u3042".dup.force_encoding('UTF-8')).should == \
+      "\xA4\xA2".dup.force_encoding('EUC-JP')
   end
 
   it "allows Strings of different encodings to the source encoding" do
     ec = Encoding::Converter.new('ascii', 'utf-8')
-    str = 'glark'.force_encoding('SJIS')
+    str = 'glark'.dup.force_encoding('SJIS')
     ec.convert(str).encoding.should == Encoding::UTF_8
   end
 
   it "reuses the given encoding pair if called multiple times" do
     ec = Encoding::Converter.new('ascii', 'SJIS')
-    ec.convert('a'.force_encoding('ASCII')).should == 'a'.force_encoding('SJIS')
-    ec.convert('b'.force_encoding('ASCII')).should == 'b'.force_encoding('SJIS')
+    ec.convert('a'.dup.force_encoding('ASCII')).should == 'a'.dup.force_encoding('SJIS')
+    ec.convert('b'.dup.force_encoding('ASCII')).should == 'b'.dup.force_encoding('SJIS')
   end
 
   it "raises UndefinedConversionError if the String contains characters invalid for the target encoding" do
     ec = Encoding::Converter.new('UTF-8', Encoding.find('macCyrillic'))
-    -> { ec.convert("\u{6543}".force_encoding('UTF-8')) }.should \
-      raise_error(Encoding::UndefinedConversionError)
+    -> { ec.convert("\u{6543}".dup.force_encoding('UTF-8')) }.should.raise(Encoding::UndefinedConversionError)
   end
 
   it "raises an ArgumentError if called on a finished stream" do
     ec = Encoding::Converter.new('UTF-8', Encoding.find('macCyrillic'))
     ec.finish
-    -> { ec.convert("\u{65}") }.should raise_error(ArgumentError)
+    -> { ec.convert("\u{65}") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/encoding/converter/finish_spec.rb b/spec/ruby/core/encoding/converter/finish_spec.rb
index 11ca7e8510..e13b7415f8 100644
--- a/spec/ruby/core/encoding/converter/finish_spec.rb
+++ b/spec/ruby/core/encoding/converter/finish_spec.rb
@@ -7,7 +7,7 @@ describe "Encoding::Converter#finish" do
 
   it "returns a String" do
     @ec.convert('foo')
-    @ec.finish.should be_an_instance_of(String)
+    @ec.finish.should.instance_of?(String)
   end
 
   it "returns an empty String if there is nothing more to convert" do
@@ -16,8 +16,8 @@ describe "Encoding::Converter#finish" do
   end
 
   it "returns the last part of the converted String if it hasn't already" do
-     @ec.convert("\u{9999}").should == "\e$B9a".force_encoding('iso-2022-jp')
-     @ec.finish.should == "\e(B".force_encoding('iso-2022-jp')
+    @ec.convert("\u{9999}").should == "\e$B9a".dup.force_encoding('iso-2022-jp')
+    @ec.finish.should == "\e(B".dup.force_encoding('iso-2022-jp')
   end
 
   it "returns a String in the destination encoding" do
diff --git a/spec/ruby/core/encoding/converter/last_error_spec.rb b/spec/ruby/core/encoding/converter/last_error_spec.rb
index 68567737b7..3984a628f5 100644
--- a/spec/ruby/core/encoding/converter/last_error_spec.rb
+++ b/spec/ruby/core/encoding/converter/last_error_spec.rb
@@ -1,54 +1,54 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter#last_error" do
   it "returns nil when the no conversion has been attempted" do
     ec = Encoding::Converter.new('ascii','utf-8')
-    ec.last_error.should be_nil
+    ec.last_error.should == nil
   end
 
   it "returns nil when the last conversion did not produce an error" do
     ec = Encoding::Converter.new('ascii','utf-8')
-    ec.convert('a'.force_encoding('ascii'))
-    ec.last_error.should be_nil
+    ec.convert('a'.dup.force_encoding('ascii'))
+    ec.last_error.should == nil
   end
 
   it "returns nil when #primitive_convert last returned :destination_buffer_full" do
     ec = Encoding::Converter.new("utf-8", "iso-2022-jp")
-    ec.primitive_convert("\u{9999}", "", 0, 0, partial_input: false) \
+    ec.primitive_convert(+"\u{9999}", +"", 0, 0, partial_input: false) \
       .should == :destination_buffer_full
-    ec.last_error.should be_nil
+    ec.last_error.should == nil
   end
 
   it "returns nil when #primitive_convert last returned :finished" do
     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
-    ec.primitive_convert("glark".force_encoding('utf-8'),"").should == :finished
-    ec.last_error.should be_nil
+    ec.primitive_convert("glark".dup.force_encoding('utf-8'), +"").should == :finished
+    ec.last_error.should == nil
   end
 
   it "returns nil if the last conversion succeeded but the penultimate failed" do
     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
-    ec.primitive_convert("\xf1abcd","").should == :invalid_byte_sequence
-    ec.primitive_convert("glark".force_encoding('utf-8'),"").should == :finished
-    ec.last_error.should be_nil
+    ec.primitive_convert(+"\xf1abcd", +"").should == :invalid_byte_sequence
+    ec.primitive_convert("glark".dup.force_encoding('utf-8'), +"").should == :finished
+    ec.last_error.should == nil
   end
 
   it "returns an Encoding::InvalidByteSequenceError when #primitive_convert last returned :invalid_byte_sequence" do
     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
-    ec.primitive_convert("\xf1abcd","").should == :invalid_byte_sequence
-    ec.last_error.should be_an_instance_of(Encoding::InvalidByteSequenceError)
+    ec.primitive_convert(+"\xf1abcd", +"").should == :invalid_byte_sequence
+    ec.last_error.should.instance_of?(Encoding::InvalidByteSequenceError)
   end
 
   it "returns an Encoding::UndefinedConversionError when #primitive_convert last returned :undefined_conversion" do
     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
-    ec.primitive_convert("\u{9876}","").should == :undefined_conversion
-    ec.last_error.should be_an_instance_of(Encoding::UndefinedConversionError)
+    ec.primitive_convert(+"\u{9876}", +"").should == :undefined_conversion
+    ec.last_error.should.instance_of?(Encoding::UndefinedConversionError)
   end
 
   it "returns an Encoding::InvalidByteSequenceError when #primitive_convert last returned :incomplete_input" do
     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
-    ec.primitive_convert("\xa4", "", nil, 10).should == :incomplete_input
-    ec.last_error.should be_an_instance_of(Encoding::InvalidByteSequenceError)
+    ec.primitive_convert(+"\xa4", +"", nil, 10).should == :incomplete_input
+    ec.last_error.should.instance_of?(Encoding::InvalidByteSequenceError)
   end
 
   it "returns an Encoding::InvalidByteSequenceError when the last call to #convert produced one" do
@@ -56,10 +56,10 @@ describe "Encoding::Converter#last_error" do
     exception = nil
     -> {
       ec.convert("\xf1abcd")
-    }.should raise_error(Encoding::InvalidByteSequenceError) { |e|
+    }.should.raise(Encoding::InvalidByteSequenceError) { |e|
       exception = e
     }
-    ec.last_error.should be_an_instance_of(Encoding::InvalidByteSequenceError)
+    ec.last_error.should.instance_of?(Encoding::InvalidByteSequenceError)
     ec.last_error.message.should == exception.message
   end
 
@@ -68,12 +68,12 @@ describe "Encoding::Converter#last_error" do
     exception = nil
     -> {
       ec.convert("\u{9899}")
-    }.should raise_error(Encoding::UndefinedConversionError) { |e|
+    }.should.raise(Encoding::UndefinedConversionError) { |e|
       exception = e
     }
-    ec.last_error.should be_an_instance_of(Encoding::UndefinedConversionError)
+    ec.last_error.should.instance_of?(Encoding::UndefinedConversionError)
     ec.last_error.message.should == exception.message
-    ec.last_error.message.should include "from UTF-8 to ISO-8859-1"
+    ec.last_error.message.should.include? "from UTF-8 to ISO-8859-1"
   end
 
   it "returns the last error of #convert with a message showing the transcoding path" do
@@ -81,11 +81,11 @@ describe "Encoding::Converter#last_error" do
     exception = nil
     -> {
       ec.convert("\xE9") # é in ISO-8859-1
-    }.should raise_error(Encoding::UndefinedConversionError) { |e|
+    }.should.raise(Encoding::UndefinedConversionError) { |e|
       exception = e
     }
-    ec.last_error.should be_an_instance_of(Encoding::UndefinedConversionError)
+    ec.last_error.should.instance_of?(Encoding::UndefinedConversionError)
     ec.last_error.message.should == exception.message
-    ec.last_error.message.should include "from ISO-8859-1 to UTF-8 to Big5"
+    ec.last_error.message.should.include? "from ISO-8859-1 to UTF-8 to Big5"
   end
 end
diff --git a/spec/ruby/core/encoding/converter/new_spec.rb b/spec/ruby/core/encoding/converter/new_spec.rb
index 9fc97263fe..bbdfb48bce 100644
--- a/spec/ruby/core/encoding/converter/new_spec.rb
+++ b/spec/ruby/core/encoding/converter/new_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter.new" do
@@ -25,7 +25,7 @@ describe "Encoding::Converter.new" do
   it "raises an Encoding::ConverterNotFoundError if both encodings are the same" do
     -> do
       Encoding::Converter.new "utf-8", "utf-8"
-    end.should raise_error(Encoding::ConverterNotFoundError)
+    end.should.raise(Encoding::ConverterNotFoundError)
   end
 
   it "calls #to_str to convert the source encoding argument to an encoding name" do
@@ -47,7 +47,7 @@ describe "Encoding::Converter.new" do
     conv.replacement.should == "fubar"
   end
 
-  it "calls #to_hash to convert the options argument to a Hash if not a Fixnum" do
+  it "calls #to_hash to convert the options argument to a Hash if not an Integer" do
     opts = mock("encoding converter options")
     opts.should_receive(:to_hash).and_return({ replace: "fubar" })
     conv = Encoding::Converter.new("us-ascii", "utf-8", **opts)
@@ -67,25 +67,25 @@ describe "Encoding::Converter.new" do
 
     -> do
       Encoding::Converter.new("us-ascii", "utf-8", replace: obj)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed true for the replacement object" do
     -> do
       Encoding::Converter.new("us-ascii", "utf-8", replace: true)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false for the replacement object" do
     -> do
       Encoding::Converter.new("us-ascii", "utf-8", replace: false)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
-  it "raises a TypeError if passed a Fixnum for the replacement object" do
+  it "raises a TypeError if passed an Integer for the replacement object" do
     -> do
       Encoding::Converter.new("us-ascii", "utf-8", replace: 1)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "accepts an empty String for the replacement object" do
@@ -107,7 +107,7 @@ describe "Encoding::Converter.new" do
 
       it "sets the replacement String to '\\uFFFD'" do
         conv = Encoding::Converter.new("us-ascii", "utf-8", replace: nil)
-        conv.replacement.should == "\u{fffd}".force_encoding("utf-8")
+        conv.replacement.should == "\u{fffd}".dup.force_encoding("utf-8")
       end
 
       it "sets the replacement String encoding to UTF-8" do
diff --git a/spec/ruby/core/encoding/converter/primitive_convert_spec.rb b/spec/ruby/core/encoding/converter/primitive_convert_spec.rb
index 802d8e7cb1..ab9ce6a992 100644
--- a/spec/ruby/core/encoding/converter/primitive_convert_spec.rb
+++ b/spec/ruby/core/encoding/converter/primitive_convert_spec.rb
@@ -1,4 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
+# frozen_string_literal: false
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter#primitive_convert" do
@@ -7,19 +8,23 @@ describe "Encoding::Converter#primitive_convert" do
   end
 
   it "accepts a nil source buffer" do
-    -> { @ec.primitive_convert(nil,"") }.should_not raise_error
+    -> { @ec.primitive_convert(nil,"") }.should_not.raise
   end
 
   it "accepts a String as the source buffer" do
-    -> { @ec.primitive_convert("","") }.should_not raise_error
+    -> { @ec.primitive_convert("","") }.should_not.raise
+  end
+
+  it "raises FrozenError when the destination buffer is a frozen String" do
+    -> { @ec.primitive_convert("", "".freeze) }.should.raise(FrozenError)
   end
 
   it "accepts nil for the destination byte offset" do
-    -> { @ec.primitive_convert("","", nil) }.should_not raise_error
+    -> { @ec.primitive_convert("","", nil) }.should_not.raise
   end
 
   it "accepts an integer for the destination byte offset" do
-    -> { @ec.primitive_convert("","a", 1) }.should_not raise_error
+    -> { @ec.primitive_convert("","a", 1) }.should_not.raise
   end
 
   it "calls #to_int to convert the destination byte offset" do
@@ -30,10 +35,10 @@ describe "Encoding::Converter#primitive_convert" do
   end
 
   it "raises an ArgumentError if the destination byte offset is greater than the bytesize of the destination buffer" do
-    -> { @ec.primitive_convert("","am", 0) }.should_not raise_error
-    -> { @ec.primitive_convert("","am", 1) }.should_not raise_error
-    -> { @ec.primitive_convert("","am", 2) }.should_not raise_error
-    -> { @ec.primitive_convert("","am", 3) }.should raise_error(ArgumentError)
+    -> { @ec.primitive_convert("","am", 0) }.should_not.raise
+    -> { @ec.primitive_convert("","am", 1) }.should_not.raise
+    -> { @ec.primitive_convert("","am", 2) }.should_not.raise
+    -> { @ec.primitive_convert("","am", 3) }.should.raise(ArgumentError)
   end
 
   it "uses the destination byte offset to determine where to write the result in the destination buffer" do
@@ -49,19 +54,19 @@ describe "Encoding::Converter#primitive_convert" do
   end
 
   it "accepts nil for the destination bytesize" do
-    -> { @ec.primitive_convert("","", nil, nil) }.should_not raise_error
+    -> { @ec.primitive_convert("","", nil, nil) }.should_not.raise
   end
 
   it "accepts an integer for the destination bytesize" do
-    -> { @ec.primitive_convert("","", nil, 0) }.should_not raise_error
+    -> { @ec.primitive_convert("","", nil, 0) }.should_not.raise
   end
 
   it "allows a destination bytesize value greater than the bytesize of the source buffer" do
-    -> { @ec.primitive_convert("am","", nil, 3) }.should_not raise_error
+    -> { @ec.primitive_convert("am","", nil, 3) }.should_not.raise
   end
 
   it "allows a destination bytesize value less than the bytesize of the source buffer" do
-    -> { @ec.primitive_convert("am","", nil, 1) }.should_not raise_error
+    -> { @ec.primitive_convert("am","", nil, 1) }.should_not.raise
   end
 
   it "calls #to_int to convert the destination byte size" do
diff --git a/spec/ruby/core/encoding/converter/primitive_errinfo_spec.rb b/spec/ruby/core/encoding/converter/primitive_errinfo_spec.rb
index 1f836b259f..580e2e37e1 100644
--- a/spec/ruby/core/encoding/converter/primitive_errinfo_spec.rb
+++ b/spec/ruby/core/encoding/converter/primitive_errinfo_spec.rb
@@ -1,4 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
+# frozen_string_literal: false
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter#primitive_errinfo" do
@@ -54,7 +55,7 @@ describe "Encoding::Converter#primitive_errinfo" do
 
   it "returns the state, source encoding, target encoding, erroneous bytes, and the read-again bytes when #convert last raised InvalidByteSequenceError" do
     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
-    -> { ec.convert("\xf1abcd") }.should raise_error(Encoding::InvalidByteSequenceError)
+    -> { ec.convert("\xf1abcd") }.should.raise(Encoding::InvalidByteSequenceError)
     ec.primitive_errinfo.should ==
       [:invalid_byte_sequence, "UTF-8", "ISO-8859-1", "\xF1", "a"]
   end
@@ -62,7 +63,7 @@ describe "Encoding::Converter#primitive_errinfo" do
   it "returns the state, source encoding, target encoding, erroneous bytes, and the read-again bytes when #finish last raised InvalidByteSequenceError" do
     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
     ec.convert("\xa4")
-    -> { ec.finish }.should raise_error(Encoding::InvalidByteSequenceError)
+    -> { ec.finish }.should.raise(Encoding::InvalidByteSequenceError)
     ec.primitive_errinfo.should == [:incomplete_input, "EUC-JP", "UTF-8", "\xA4", ""]
   end
 end
diff --git a/spec/ruby/core/encoding/converter/putback_spec.rb b/spec/ruby/core/encoding/converter/putback_spec.rb
index 87495eaf3f..a85cec5145 100644
--- a/spec/ruby/core/encoding/converter/putback_spec.rb
+++ b/spec/ruby/core/encoding/converter/putback_spec.rb
@@ -1,14 +1,14 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 
 describe "Encoding::Converter#putback" do
   before :each do
     @ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
-    @ret = @ec.primitive_convert(@src="abc\xa1def", @dst="", nil, 10)
+    @ret = @ec.primitive_convert(@src=+"abc\xa1def", @dst=+"", nil, 10)
   end
 
   it "returns a String" do
-    @ec.putback.should be_an_instance_of(String)
+    @ec.putback.should.instance_of?(String)
   end
 
   it "returns a String in the source encoding" do
@@ -34,14 +34,23 @@ describe "Encoding::Converter#putback" do
     @ec.putback.should == ""
   end
 
+  it "returns the problematic bytes for UTF-16LE" do
+    ec = Encoding::Converter.new("utf-16le", "iso-8859-1")
+    src = +"\x00\xd8\x61\x00"
+    dst = +""
+    ec.primitive_convert(src, dst).should == :invalid_byte_sequence
+    ec.primitive_errinfo.should == [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "a\x00"]
+    ec.putback.should == "a\x00".dup.force_encoding("utf-16le")
+    ec.putback.should == ""
+  end
+
   it "accepts an integer argument corresponding to the number of bytes to be put back" do
     ec = Encoding::Converter.new("utf-16le", "iso-8859-1")
-    src = "\x00\xd8\x61\x00"
-    dst = ""
+    src = +"\x00\xd8\x61\x00"
+    dst = +""
     ec.primitive_convert(src, dst).should == :invalid_byte_sequence
     ec.primitive_errinfo.should == [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "a\x00"]
-    ec.putback(1).should == "\x00".force_encoding("utf-16le")
-    ec.putback.should == "a".force_encoding("utf-16le")
+    ec.putback(2).should == "a\x00".dup.force_encoding("utf-16le")
     ec.putback.should == ""
   end
 end
diff --git a/spec/ruby/core/encoding/converter/replacement_spec.rb b/spec/ruby/core/encoding/converter/replacement_spec.rb
index 5ca42e7e5a..c25ec36517 100644
--- a/spec/ruby/core/encoding/converter/replacement_spec.rb
+++ b/spec/ruby/core/encoding/converter/replacement_spec.rb
@@ -13,7 +13,7 @@ describe "Encoding::Converter#replacement" do
 
   it "returns \\uFFFD when the destination encoding is UTF-8" do
     ec = Encoding::Converter.new("us-ascii", "utf-8")
-    ec.replacement.should == "\u{fffd}".force_encoding('utf-8')
+    ec.replacement.should == "\u{fffd}".dup.force_encoding('utf-8')
     ec.replacement.encoding.should == Encoding::UTF_8
   end
 end
@@ -33,38 +33,36 @@ describe "Encoding::Converter#replacement=" do
 
   it "raises a TypeError if assigned a non-String argument" do
     ec = Encoding::Converter.new("utf-8", "us-ascii")
-    -> { ec.replacement = nil }.should raise_error(TypeError)
+    -> { ec.replacement = nil }.should.raise(TypeError)
   end
 
   it "sets #replacement" do
     ec = Encoding::Converter.new("us-ascii", "utf-8")
-    ec.replacement.should == "\u{fffd}".force_encoding('utf-8')
+    ec.replacement.should == "\u{fffd}".dup.force_encoding('utf-8')
     ec.replacement = '?'.encode('utf-8')
-    ec.replacement.should == '?'.force_encoding('utf-8')
+    ec.replacement.should == '?'.dup.force_encoding('utf-8')
   end
 
   it "raises an UndefinedConversionError is the argument cannot be converted into the destination encoding" do
     ec = Encoding::Converter.new("sjis", "ascii")
-    utf8_q = "\u{986}".force_encoding('utf-8')
-    ec.primitive_convert(utf8_q.dup, "").should == :undefined_conversion
-    -> { ec.replacement = utf8_q }.should \
-      raise_error(Encoding::UndefinedConversionError)
+    utf8_q = "\u{986}".dup.force_encoding('utf-8')
+    ec.primitive_convert(utf8_q.dup, +"").should == :undefined_conversion
+    -> { ec.replacement = utf8_q }.should.raise(Encoding::UndefinedConversionError)
   end
 
   it "does not change the replacement character if the argument cannot be converted into the destination encoding" do
     ec = Encoding::Converter.new("sjis", "ascii")
-    utf8_q = "\u{986}".force_encoding('utf-8')
-    ec.primitive_convert(utf8_q.dup, "").should == :undefined_conversion
-    -> { ec.replacement = utf8_q }.should \
-      raise_error(Encoding::UndefinedConversionError)
-    ec.replacement.should == "?".force_encoding('us-ascii')
+    utf8_q = "\u{986}".dup.force_encoding('utf-8')
+    ec.primitive_convert(utf8_q.dup, +"").should == :undefined_conversion
+    -> { ec.replacement = utf8_q }.should.raise(Encoding::UndefinedConversionError)
+    ec.replacement.should == "?".dup.force_encoding('us-ascii')
   end
 
   it "uses the replacement character" do
     ec = Encoding::Converter.new("utf-8", "us-ascii", :invalid => :replace, :undef => :replace)
     ec.replacement = "!"
-    dest = ""
-    status = ec.primitive_convert "中文123", dest
+    dest = +""
+    status = ec.primitive_convert(+"中文123", dest)
 
     status.should == :finished
     dest.should == "!!123"
diff --git a/spec/ruby/core/encoding/converter/search_convpath_spec.rb b/spec/ruby/core/encoding/converter/search_convpath_spec.rb
index 0882af5539..cac44765f8 100644
--- a/spec/ruby/core/encoding/converter/search_convpath_spec.rb
+++ b/spec/ruby/core/encoding/converter/search_convpath_spec.rb
@@ -23,8 +23,8 @@ describe "Encoding::Converter.search_convpath" do
   end
 
   it "raises an Encoding::ConverterNotFoundError if no conversion path exists" do
-   -> do
-     Encoding::Converter.search_convpath(Encoding::BINARY, Encoding::Emacs_Mule)
-   end.should raise_error(Encoding::ConverterNotFoundError)
+    -> do
+      Encoding::Converter.search_convpath(Encoding::BINARY, Encoding::Emacs_Mule)
+    end.should.raise(Encoding::ConverterNotFoundError)
   end
 end
diff --git a/spec/ruby/core/encoding/default_external_spec.rb b/spec/ruby/core/encoding/default_external_spec.rb
index e2cb9b02f4..2a2bd7f6ae 100644
--- a/spec/ruby/core/encoding/default_external_spec.rb
+++ b/spec/ruby/core/encoding/default_external_spec.rb
@@ -10,13 +10,19 @@ describe "Encoding.default_external" do
   end
 
   it "returns an Encoding object" do
-    Encoding.default_external.should be_an_instance_of(Encoding)
+    Encoding.default_external.should.instance_of?(Encoding)
   end
 
   it "returns the default external encoding" do
     Encoding.default_external = Encoding::SHIFT_JIS
     Encoding.default_external.should == Encoding::SHIFT_JIS
   end
+
+  platform_is :windows do
+    it 'is UTF-8 by default on Windows' do
+      Encoding.default_external.should == Encoding::UTF_8
+    end
+  end
 end
 
 describe "Encoding.default_external=" do
@@ -54,10 +60,10 @@ describe "Encoding.default_external=" do
   end
 
   it "raises a TypeError unless the argument is an Encoding or convertible to a String" do
-    -> { Encoding.default_external = [] }.should raise_error(TypeError)
+    -> { Encoding.default_external = [] }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if the argument is nil" do
-    -> { Encoding.default_external = nil }.should raise_error(ArgumentError)
+    -> { Encoding.default_external = nil }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/encoding/default_internal_spec.rb b/spec/ruby/core/encoding/default_internal_spec.rb
index 855f4e9f32..38aef9dce9 100644
--- a/spec/ruby/core/encoding/default_internal_spec.rb
+++ b/spec/ruby/core/encoding/default_internal_spec.rb
@@ -10,17 +10,17 @@ describe "Encoding.default_internal" do
   end
 
   it "is nil by default" do
-    Encoding.default_internal.should be_nil
+    Encoding.default_internal.should == nil
   end
 
   it "returns an Encoding object if a default internal encoding is set" do
     Encoding.default_internal = Encoding::ASCII
-    Encoding.default_internal.should be_an_instance_of(Encoding)
+    Encoding.default_internal.should.instance_of?(Encoding)
   end
 
   it "returns nil if no default internal encoding is set" do
     Encoding.default_internal = nil
-    Encoding.default_internal.should be_nil
+    Encoding.default_internal.should == nil
   end
 
   it "returns the default internal encoding" do
@@ -60,15 +60,15 @@ describe "Encoding.default_internal=" do
     obj = mock('string')
     obj.should_receive(:to_str).at_least(1).times.and_return(1)
 
-    -> { Encoding.default_internal = obj }.should raise_error(TypeError)
+    -> { Encoding.default_internal = obj }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed an object not providing #to_str" do
-    -> { Encoding.default_internal = mock("encoding") }.should raise_error(TypeError)
+    -> { Encoding.default_internal = mock("encoding") }.should.raise(TypeError)
   end
 
   it "accepts an argument of nil to unset the default internal encoding" do
     Encoding.default_internal = nil
-    Encoding.default_internal.should be_nil
+    Encoding.default_internal.should == nil
   end
 end
diff --git a/spec/ruby/core/encoding/dummy_spec.rb b/spec/ruby/core/encoding/dummy_spec.rb
index 75ffcd5a4e..05530a8186 100644
--- a/spec/ruby/core/encoding/dummy_spec.rb
+++ b/spec/ruby/core/encoding/dummy_spec.rb
@@ -2,13 +2,24 @@ require_relative '../../spec_helper'
 
 describe "Encoding#dummy?" do
   it "returns false for proper encodings" do
-    Encoding::UTF_8.dummy?.should be_false
-    Encoding::ASCII.dummy?.should be_false
+    Encoding::UTF_8.dummy?.should == false
+    Encoding::ASCII.dummy?.should == false
   end
 
   it "returns true for dummy encodings" do
-    Encoding::ISO_2022_JP.dummy?.should be_true
-    Encoding::CP50221.dummy?.should be_true
-    Encoding::UTF_7.dummy?.should be_true
+    Encoding::ISO_2022_JP.dummy?.should == true
+    Encoding::CP50221.dummy?.should == true
+    Encoding::UTF_7.dummy?.should == true
+  end
+
+  it "returns true for UTF_16 and UTF_32" do
+    Encoding::UTF_16.should.dummy?
+    Encoding::UTF_32.should.dummy?
+  end
+
+  it "implies not #ascii_compatible?" do
+    Encoding.list.select(&:dummy?).each do |encoding|
+      encoding.should_not.ascii_compatible?
+    end
   end
 end
diff --git a/spec/ruby/core/encoding/find_spec.rb b/spec/ruby/core/encoding/find_spec.rb
index 8a0873070f..c5356560eb 100644
--- a/spec/ruby/core/encoding/find_spec.rb
+++ b/spec/ruby/core/encoding/find_spec.rb
@@ -7,18 +7,18 @@ describe "Encoding.find" do
 
   it "returns the corresponding Encoding object if given a valid encoding name" do
     @encodings.each do |enc|
-      Encoding.find(enc).should be_an_instance_of(Encoding)
+      Encoding.find(enc).should.instance_of?(Encoding)
     end
   end
 
   it "returns the corresponding Encoding object if given a valid alias name" do
     Encoding.aliases.keys.each do |enc_alias|
-      Encoding.find(enc_alias).should be_an_instance_of(Encoding)
+      Encoding.find(enc_alias).should.instance_of?(Encoding)
     end
   end
 
   it "raises a TypeError if passed a Symbol" do
-    -> { Encoding.find(:"utf-8") }.should raise_error(TypeError)
+    -> { Encoding.find(:"utf-8") }.should.raise(TypeError)
   end
 
   it "returns the passed Encoding object" do
@@ -50,7 +50,7 @@ describe "Encoding.find" do
   end
 
   it "raises an ArgumentError if the given encoding does not exist" do
-    -> { Encoding.find('dh2dh278d') }.should raise_error(ArgumentError)
+    -> { Encoding.find('dh2dh278d') }.should.raise(ArgumentError, 'unknown encoding name - dh2dh278d')
   end
 
   # Not sure how to do a better test, since locale depends on weird platform-specific stuff
diff --git a/spec/ruby/core/encoding/fixtures/classes.rb b/spec/ruby/core/encoding/fixtures/classes.rb
index 12e9a4f348..943865e8d8 100644
--- a/spec/ruby/core/encoding/fixtures/classes.rb
+++ b/spec/ruby/core/encoding/fixtures/classes.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 module EncodingSpecs
   class UndefinedConversionError
     def self.exception
diff --git a/spec/ruby/core/encoding/inspect_spec.rb b/spec/ruby/core/encoding/inspect_spec.rb
index 9a930b2a77..ab7f8cf9fc 100644
--- a/spec/ruby/core/encoding/inspect_spec.rb
+++ b/spec/ruby/core/encoding/inspect_spec.rb
@@ -2,12 +2,26 @@ require_relative '../../spec_helper'
 
 describe "Encoding#inspect" do
   it "returns a String" do
-    Encoding::UTF_8.inspect.should be_an_instance_of(String)
+    Encoding::UTF_8.inspect.should.instance_of?(String)
   end
 
-  it "returns #<Encoding:name> for a non-dummy encoding named 'name'" do
-    Encoding.list.to_a.reject {|e| e.dummy? }.each do |enc|
-      enc.inspect.should =~ /#<Encoding:#{enc.name}>/
+  ruby_version_is ""..."3.4" do
+    it "returns #<Encoding:name> for a non-dummy encoding named 'name'" do
+      Encoding.list.to_a.reject {|e| e.dummy? }.each do |enc|
+        enc.inspect.should =~ /#<Encoding:#{enc.name}>/
+      end
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "returns #<Encoding:name> for a non-dummy encoding named 'name'" do
+      Encoding.list.to_a.reject {|e| e.dummy? }.each do |enc|
+        if enc.name == "ASCII-8BIT"
+          enc.inspect.should == "#<Encoding:BINARY (ASCII-8BIT)>"
+        else
+          enc.inspect.should =~ /#<Encoding:#{enc.name}>/
+        end
+      end
     end
   end
 
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_name_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_name_spec.rb
index f5fa6f55e3..7d3cc77c0b 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_name_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_name_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::InvalidByteSequenceError#destination_encoding_name" do
@@ -7,8 +8,8 @@ describe "Encoding::InvalidByteSequenceError#destination_encoding_name" do
   end
 
   it "returns a String" do
-    @exception.destination_encoding_name.should be_an_instance_of(String)
-    @exception2.destination_encoding_name.should be_an_instance_of(String)
+    @exception.destination_encoding_name.should.instance_of?(String)
+    @exception2.destination_encoding_name.should.instance_of?(String)
   end
 
   it "is equal to the destination encoding name of the object that raised it" do
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_spec.rb
index 43be3ddd71..264c409b1c 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/destination_encoding_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::InvalidByteSequenceError#destination_encoding" do
@@ -7,8 +8,8 @@ describe "Encoding::InvalidByteSequenceError#destination_encoding" do
   end
 
   it "returns an Encoding object" do
-    @exception.destination_encoding.should be_an_instance_of(Encoding)
-    @exception2.destination_encoding.should be_an_instance_of(Encoding)
+    @exception.destination_encoding.should.instance_of?(Encoding)
+    @exception2.destination_encoding.should.instance_of?(Encoding)
   end
 
   it "is equal to the destination encoding of the object that raised it" do
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/error_bytes_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/error_bytes_spec.rb
index a8f7354b16..40a9a35caf 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/error_bytes_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/error_bytes_spec.rb
@@ -1,4 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::InvalidByteSequenceError#error_bytes" do
@@ -8,8 +9,8 @@ describe "Encoding::InvalidByteSequenceError#error_bytes" do
   end
 
   it "returns a String" do
-    @exception.error_bytes.should be_an_instance_of(String)
-    @exception2.error_bytes.should be_an_instance_of(String)
+    @exception.error_bytes.should.instance_of?(String)
+    @exception2.error_bytes.should.instance_of?(String)
   end
 
   it "returns the bytes that caused the exception" do
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/incomplete_input_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/incomplete_input_spec.rb
index e3ef3e4557..143db7b6da 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/incomplete_input_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/incomplete_input_spec.rb
@@ -1,29 +1,28 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 
 describe "Encoding::InvalidByteSequenceError#incomplete_input?" do
-
   it "returns nil by default" do
-    Encoding::InvalidByteSequenceError.new.incomplete_input?.should be_nil
+    Encoding::InvalidByteSequenceError.new.incomplete_input?.should == nil
   end
 
   it "returns true if #primitive_convert returned :incomplete_input for the same data" do
     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
-    ec.primitive_convert("\xA1",'').should == :incomplete_input
+    ec.primitive_convert(+"\xA1", +'').should == :incomplete_input
     begin
       ec.convert("\xA1")
     rescue Encoding::InvalidByteSequenceError => e
-      e.incomplete_input?.should be_true
+      e.incomplete_input?.should == true
     end
   end
 
   it "returns false if #primitive_convert returned :invalid_byte_sequence for the same data" do
     ec = Encoding::Converter.new("ascii", "utf-8")
-    ec.primitive_convert("\xfffffffff",'').should == :invalid_byte_sequence
+    ec.primitive_convert(+"\xfffffffff", +'').should == :invalid_byte_sequence
     begin
       ec.convert("\xfffffffff")
     rescue Encoding::InvalidByteSequenceError => e
-      e.incomplete_input?.should be_false
+      e.incomplete_input?.should == false
     end
   end
 end
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/readagain_bytes_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/readagain_bytes_spec.rb
index 93823b5db4..e4fc81aac6 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/readagain_bytes_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/readagain_bytes_spec.rb
@@ -1,4 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::InvalidByteSequenceError#readagain_bytes" do
@@ -8,17 +9,17 @@ describe "Encoding::InvalidByteSequenceError#readagain_bytes" do
   end
 
   it "returns a String" do
-    @exception.readagain_bytes.should be_an_instance_of(String)
-    @exception2.readagain_bytes.should be_an_instance_of(String)
+    @exception.readagain_bytes.should.instance_of?(String)
+    @exception2.readagain_bytes.should.instance_of?(String)
   end
 
   it "returns the bytes to be read again" do
     @exception.readagain_bytes.size.should == 1
-    @exception.readagain_bytes.should == "a".force_encoding('binary')
+    @exception.readagain_bytes.should == "a".dup.force_encoding('binary')
     @exception.readagain_bytes.should == @errinfo[-1]
 
     @exception2.readagain_bytes.size.should == 1
-    @exception2.readagain_bytes.should == "\xFF".force_encoding('binary')
+    @exception2.readagain_bytes.should == "\xFF".dup.force_encoding('binary')
     @exception2.readagain_bytes.should == @errinfo2[-1]
   end
 
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_name_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_name_spec.rb
index bd3a51cbc5..b00e1ad4e8 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_name_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_name_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#source_encoding_name" do
@@ -7,7 +8,7 @@ describe "Encoding::UndefinedConversionError#source_encoding_name" do
   end
 
   it "returns a String" do
-    @exception.source_encoding_name.should be_an_instance_of(String)
+    @exception.source_encoding_name.should.instance_of?(String)
   end
 
   it "is equal to the source encoding name of the object that raised it" do
diff --git a/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_spec.rb b/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_spec.rb
index f43d6d5830..32ad25dbb5 100644
--- a/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_spec.rb
+++ b/spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::InvalidByteSequenceError#source_encoding" do
@@ -7,8 +8,8 @@ describe "Encoding::InvalidByteSequenceError#source_encoding" do
   end
 
   it "returns an Encoding object" do
-    @exception.source_encoding.should be_an_instance_of(Encoding)
-    @exception2.source_encoding.should be_an_instance_of(Encoding)
+    @exception.source_encoding.should.instance_of?(Encoding)
+    @exception2.source_encoding.should.instance_of?(Encoding)
   end
 
   it "is equal to the source encoding of the object that raised it" do
diff --git a/spec/ruby/core/encoding/list_spec.rb b/spec/ruby/core/encoding/list_spec.rb
index 2a2078974e..9fe336c608 100644
--- a/spec/ruby/core/encoding/list_spec.rb
+++ b/spec/ruby/core/encoding/list_spec.rb
@@ -2,38 +2,46 @@ require_relative '../../spec_helper'
 
 describe "Encoding.list" do
   it "returns an Array" do
-    Encoding.list.should be_an_instance_of(Array)
+    Encoding.list.should.instance_of?(Array)
   end
 
   it "returns an Array of Encoding objects" do
     Encoding.list.each do |enc|
-      enc.should be_an_instance_of(Encoding)
+      enc.should.instance_of?(Encoding)
     end
   end
 
   it "returns each encoding only once" do
-    orig = Encoding.list.map {|e| e.name}
+    orig = Encoding.list.map { |e| e.name }
     orig.should == orig.uniq
   end
 
   it "includes the default external encoding" do
-    Encoding.list.include?(Encoding.default_external).should be_true
+    Encoding.list.include?(Encoding.default_external).should == true
   end
 
   it "does not include any alias names" do
     Encoding.aliases.keys.each do |enc_alias|
-      Encoding.list.include?(enc_alias).should be_false
+      Encoding.list.include?(enc_alias).should == false
     end
   end
 
   it "includes all aliased encodings" do
     Encoding.aliases.values.each do |enc_alias|
-      Encoding.list.include?(Encoding.find(enc_alias)).should be_true
+      Encoding.list.include?(Encoding.find(enc_alias)).should == true
     end
   end
 
   it "includes dummy encodings" do
-    Encoding.list.select {|e| e.dummy?}.should_not == []
+    Encoding.list.select { |e| e.dummy? }.should_not == []
+  end
+
+  it 'includes UTF-8 encoding' do
+    Encoding.list.should.include?(Encoding::UTF_8)
+  end
+
+  it 'includes CESU-8 encoding' do
+    Encoding.list.should.include?(Encoding::CESU_8)
   end
 
   # TODO: Find example that illustrates this
diff --git a/spec/ruby/core/encoding/locale_charmap_spec.rb b/spec/ruby/core/encoding/locale_charmap_spec.rb
index 5963a8beb5..0d77bf227b 100644
--- a/spec/ruby/core/encoding/locale_charmap_spec.rb
+++ b/spec/ruby/core/encoding/locale_charmap_spec.rb
@@ -2,44 +2,55 @@ require_relative '../../spec_helper'
 
 describe "Encoding.locale_charmap" do
   it "returns a String" do
-    Encoding.locale_charmap.should be_an_instance_of(String)
+    Encoding.locale_charmap.should.instance_of?(String)
   end
 
-  # FIXME: Get this working on Windows
-  platform_is :linux do
-    it "returns a value based on the LC_ALL environment variable" do
-      old_lc_all = ENV['LC_ALL']
-      ENV['LC_ALL'] = 'C'
-      ruby_exe("print Encoding.locale_charmap").should == 'ANSI_X3.4-1968'
-      ENV['LC_ALL'] = old_lc_all
+  describe "when setting LC_ALL=C" do
+    before :each do
+      @old_lc_all = ENV['LC_ALL']
     end
-  end
 
-  platform_is :freebsd, :openbsd, :darwin do
-    it "returns a value based on the LC_ALL environment variable" do
-      old_lc_all = ENV['LC_ALL']
-      ENV['LC_ALL'] = 'C'
-      ruby_exe("print Encoding.locale_charmap").should == 'US-ASCII'
-      ENV['LC_ALL'] = old_lc_all
+    after :each do
+      ENV['LC_ALL'] = @old_lc_all
     end
-  end
 
-  platform_is :netbsd do
-    it "returns a value based on the LC_ALL environment variable" do
-      old_lc_all = ENV['LC_ALL']
-      ENV['LC_ALL'] = 'C'
-      ruby_exe("print Encoding.locale_charmap").should == '646'
-      ENV['LC_ALL'] = old_lc_all
+    # FIXME: Get this working on Windows
+    platform_is :linux do
+      platform_is_not :android do
+        it "returns a value based on the LC_ALL environment variable" do
+          ENV['LC_ALL'] = 'C'
+          ruby_exe("print Encoding.locale_charmap").should == 'ANSI_X3.4-1968'
+        end
+      end
+    end
+
+    platform_is :freebsd, :openbsd, :darwin do
+      it "returns a value based on the LC_ALL environment variable" do
+        ENV['LC_ALL'] = 'C'
+        ruby_exe("print Encoding.locale_charmap").should == 'US-ASCII'
+      end
+    end
+
+    platform_is :netbsd do
+      it "returns a value based on the LC_ALL environment variable" do
+        ENV['LC_ALL'] = 'C'
+        ruby_exe("print Encoding.locale_charmap").should == '646'
+      end
+    end
+
+    platform_is :android do
+      it "always returns UTF-8" do
+        ENV['LC_ALL'] = 'C'
+        ruby_exe("print Encoding.locale_charmap").should == 'UTF-8'
+      end
     end
-  end
 
-  platform_is :bsd, :darwin, :linux do
-    it "is unaffected by assigning to ENV['LC_ALL'] in the same process" do
-      old_charmap = Encoding.locale_charmap
-      old_lc_all = ENV['LC_ALL']
-      ENV['LC_ALL'] = 'C'
-      Encoding.locale_charmap.should == old_charmap
-      ENV['LC_ALL'] = old_lc_all
+    platform_is :bsd, :darwin, :linux do
+      it "is unaffected by assigning to ENV['LC_ALL'] in the same process" do
+        old_charmap = Encoding.locale_charmap
+        ENV['LC_ALL'] = 'C'
+        Encoding.locale_charmap.should == old_charmap
+      end
     end
   end
 end
diff --git a/spec/ruby/core/encoding/name_list_spec.rb b/spec/ruby/core/encoding/name_list_spec.rb
index 836381c4d8..1ba8d383bc 100644
--- a/spec/ruby/core/encoding/name_list_spec.rb
+++ b/spec/ruby/core/encoding/name_list_spec.rb
@@ -2,22 +2,22 @@ require_relative '../../spec_helper'
 
 describe "Encoding.name_list" do
   it "returns an Array" do
-    Encoding.name_list.should be_an_instance_of(Array)
+    Encoding.name_list.should.instance_of?(Array)
   end
 
   it "returns encoding names as Strings" do
-    Encoding.name_list.each {|e| e.should be_an_instance_of(String) }
+    Encoding.name_list.each {|e| e.should.instance_of?(String) }
   end
 
   it "includes all aliases" do
     Encoding.aliases.keys.each do |enc_alias|
-      Encoding.name_list.include?(enc_alias).should be_true
+      Encoding.name_list.include?(enc_alias).should == true
     end
   end
 
   it "includes all non-dummy encodings" do
     Encoding.list.each do |enc|
-      Encoding.name_list.include?(enc.name).should be_true
+      Encoding.name_list.include?(enc.name).should == true
     end
   end
 end
diff --git a/spec/ruby/core/encoding/name_spec.rb b/spec/ruby/core/encoding/name_spec.rb
index 5eadb1d2f5..1d625c9379 100644
--- a/spec/ruby/core/encoding/name_spec.rb
+++ b/spec/ruby/core/encoding/name_spec.rb
@@ -1,5 +1,15 @@
-require_relative 'shared/name'
+require_relative "../../spec_helper"
 
 describe "Encoding#name" do
-  it_behaves_like :encoding_name, :name
+  it "returns a String" do
+    Encoding.list.each do |e|
+      e.name.should.instance_of?(String)
+    end
+  end
+
+  it "uniquely identifies an encoding" do
+    Encoding.list.each do |e|
+      e.should == Encoding.find(e.name)
+    end
+  end
 end
diff --git a/spec/ruby/core/encoding/names_spec.rb b/spec/ruby/core/encoding/names_spec.rb
index 9ded043bbb..e6bcbf474a 100644
--- a/spec/ruby/core/encoding/names_spec.rb
+++ b/spec/ruby/core/encoding/names_spec.rb
@@ -4,7 +4,7 @@ describe "Encoding#names" do
   it "returns an Array" do
     Encoding.name_list.each do |name|
       e = Encoding.find(name) or next
-      e.names.should be_an_instance_of(Array)
+      e.names.should.instance_of?(Array)
     end
   end
 
@@ -12,7 +12,7 @@ describe "Encoding#names" do
     Encoding.name_list.each do |name|
       e = Encoding.find(name) or next
       e.names.each do |this_name|
-        this_name.should be_an_instance_of(String)
+        this_name.should.instance_of?(String)
       end
     end
   end
@@ -29,7 +29,7 @@ describe "Encoding#names" do
       e = Encoding.find(name) or next
       aliases = Encoding.aliases.select{|a,n| n == name}.keys
       names = e.names
-      aliases.each {|a| names.include?(a).should be_true}
+      aliases.each {|a| names.include?(a).should == true}
     end
   end
 end
diff --git a/spec/ruby/core/encoding/replicate_spec.rb b/spec/ruby/core/encoding/replicate_spec.rb
index 717e9cea72..9fe0ba8747 100644
--- a/spec/ruby/core/encoding/replicate_spec.rb
+++ b/spec/ruby/core/encoding/replicate_spec.rb
@@ -1,46 +1,8 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 
 describe "Encoding#replicate" do
-  before :all do
-    @i = 0
-  end
-
-  before :each do
-    @i += 1
-    @prefix = "RS#{@i}"
-  end
-
-  it "returns a replica of ASCII" do
-    name = @prefix + '-ASCII'
-    e = Encoding::ASCII.replicate(name)
-    e.name.should == name
-    "a".force_encoding(e).valid_encoding?.should be_true
-    "\x80".force_encoding(e).valid_encoding?.should be_false
-  end
-
-  it "returns a replica of UTF-8" do
-    name = @prefix + 'UTF-8'
-    e = Encoding::UTF_8.replicate(name)
-    e.name.should == name
-    "a".force_encoding(e).valid_encoding?.should be_true
-    "\u3042".force_encoding(e).valid_encoding?.should be_true
-    "\x80".force_encoding(e).valid_encoding?.should be_false
-  end
-
-  it "returns a replica of UTF-16BE" do
-    name = @prefix + 'UTF-16-BE'
-    e = Encoding::UTF_16BE.replicate(name)
-    e.name.should == name
-    "a".force_encoding(e).valid_encoding?.should be_false
-    "\x30\x42".force_encoding(e).valid_encoding?.should be_true
-    "\x80".force_encoding(e).valid_encoding?.should be_false
-  end
-
-  it "returns a replica of ISO-2022-JP" do
-    name = @prefix + 'ISO-2022-JP'
-    e = Encoding::ISO_2022_JP.replicate(name)
-    e.name.should == name
-    e.dummy?.should be_true
+  it "has been removed" do
+    Encoding::US_ASCII.should_not.respond_to?(:replicate, true)
   end
 end
diff --git a/spec/ruby/core/encoding/shared/name.rb b/spec/ruby/core/encoding/shared/name.rb
deleted file mode 100644
index cd37ea06db..0000000000
--- a/spec/ruby/core/encoding/shared/name.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe :encoding_name, shared: true do
-  it "returns a String" do
-    Encoding.list.each do |e|
-      e.send(@method).should be_an_instance_of(String)
-    end
-  end
-
-  it "uniquely identifies an encoding" do
-    Encoding.list.each do |e|
-      e.should == Encoding.find(e.send(@method))
-    end
-  end
-end
diff --git a/spec/ruby/core/encoding/to_s_spec.rb b/spec/ruby/core/encoding/to_s_spec.rb
index 82d282386b..ee5e3b4abe 100644
--- a/spec/ruby/core/encoding/to_s_spec.rb
+++ b/spec/ruby/core/encoding/to_s_spec.rb
@@ -1,5 +1,7 @@
-require_relative 'shared/name'
+require_relative "../../spec_helper"
 
 describe "Encoding#to_s" do
-  it_behaves_like :encoding_name, :to_s
+  it "is an alias of Encoding#name" do
+    Encoding.instance_method(:to_s).should == Encoding.instance_method(:name)
+  end
 end
diff --git a/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_name_spec.rb b/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_name_spec.rb
index 106fc7ecac..bc36695ca7 100644
--- a/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_name_spec.rb
+++ b/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_name_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#destination_encoding_name" do
@@ -6,7 +7,7 @@ describe "Encoding::UndefinedConversionError#destination_encoding_name" do
   end
 
   it "returns a String" do
-    @exception.destination_encoding_name.should be_an_instance_of(String)
+    @exception.destination_encoding_name.should.instance_of?(String)
   end
 
   it "is equal to the destination encoding name of the object that raised it" do
diff --git a/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_spec.rb b/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_spec.rb
index c6e24732fd..c0fcf8de58 100644
--- a/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_spec.rb
+++ b/spec/ruby/core/encoding/undefined_conversion_error/destination_encoding_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#destination_encoding" do
@@ -6,7 +7,7 @@ describe "Encoding::UndefinedConversionError#destination_encoding" do
   end
 
   it "returns an Encoding object" do
-    @exception.destination_encoding.should be_an_instance_of(Encoding)
+    @exception.destination_encoding.should.instance_of?(Encoding)
   end
 
   it "is equal to the destination encoding of the object that raised it" do
diff --git a/spec/ruby/core/encoding/undefined_conversion_error/error_char_spec.rb b/spec/ruby/core/encoding/undefined_conversion_error/error_char_spec.rb
index 780d81c1ee..333acf5ee6 100644
--- a/spec/ruby/core/encoding/undefined_conversion_error/error_char_spec.rb
+++ b/spec/ruby/core/encoding/undefined_conversion_error/error_char_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#error_char" do
@@ -7,8 +8,8 @@ describe "Encoding::UndefinedConversionError#error_char" do
   end
 
   it "returns a String" do
-    @exception.error_char.should be_an_instance_of(String)
-    @exception2.error_char.should be_an_instance_of(String)
+    @exception.error_char.should.instance_of?(String)
+    @exception2.error_char.should.instance_of?(String)
   end
 
   it "returns the one-character String that caused the exception" do
diff --git a/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_name_spec.rb b/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_name_spec.rb
index 3b697cb82f..4932a25ed7 100644
--- a/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_name_spec.rb
+++ b/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_name_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#source_encoding_name" do
@@ -7,7 +8,7 @@ describe "Encoding::UndefinedConversionError#source_encoding_name" do
   end
 
   it "returns a String" do
-    @exception.source_encoding_name.should be_an_instance_of(String)
+    @exception.source_encoding_name.should.instance_of?(String)
   end
 
   it "is equal to the source encoding name of the object that raised it" do
diff --git a/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_spec.rb b/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_spec.rb
index 9101d51e11..cf12020ad2 100644
--- a/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_spec.rb
+++ b/spec/ruby/core/encoding/undefined_conversion_error/source_encoding_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative '../fixtures/classes'
 
 describe "Encoding::UndefinedConversionError#source_encoding" do
@@ -7,8 +8,8 @@ describe "Encoding::UndefinedConversionError#source_encoding" do
   end
 
   it "returns an Encoding object" do
-    @exception.source_encoding.should be_an_instance_of(Encoding)
-    @exception2.source_encoding.should be_an_instance_of(Encoding)
+    @exception.source_encoding.should.instance_of?(Encoding)
+    @exception2.source_encoding.should.instance_of?(Encoding)
   end
 
   it "is equal to the source encoding of the object that raised it" do
diff --git a/spec/ruby/core/enumerable/all_spec.rb b/spec/ruby/core/enumerable/all_spec.rb
index 8af80896a9..cbdd63f86a 100644
--- a/spec/ruby/core/enumerable/all_spec.rb
+++ b/spec/ruby/core/enumerable/all_spec.rb
@@ -10,66 +10,57 @@ describe "Enumerable#all?" do
   end
 
   it "always returns true on empty enumeration" do
-    @empty.all?.should == true
+    @empty.should.all?
     @empty.all? { nil }.should == true
 
-    [].all?.should == true
+    [].should.all?
     [].all? { false }.should == true
 
-    {}.all?.should == true
+    {}.should.all?
     {}.all? { nil }.should == true
   end
 
   it "raises an ArgumentError when more than 1 argument is provided" do
-    -> { @enum.all?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { [].all?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { {}.all?(1, 2, 3) }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is ""..."2.5" do
-    it "raises an ArgumentError when any arguments provided" do
-      -> { @enum.all?(Proc.new {}) }.should raise_error(ArgumentError)
-      -> { @enum.all?(nil) }.should raise_error(ArgumentError)
-      -> { @empty.all?(1) }.should raise_error(ArgumentError)
-      -> { @enum1.all?(1) {} }.should raise_error(ArgumentError)
-    end
+    -> { @enum.all?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { [].all?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { {}.all?(1, 2, 3) }.should.raise(ArgumentError)
   end
 
   it "does not hide exceptions out of #each" do
     -> {
       EnumerableSpecs::ThrowingEach.new.all?
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
 
     -> {
       EnumerableSpecs::ThrowingEach.new.all? { false }
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
   end
 
   describe "with no block" do
     it "returns true if no elements are false or nil" do
-      @enum.all?.should == true
-      @enum1.all?.should == true
-      @enum2.all?.should == false
+      @enum.should.all?
+      @enum1.should.all?
+      @enum2.should_not.all?
 
-      EnumerableSpecs::Numerous.new('a','b','c').all?.should == true
-      EnumerableSpecs::Numerous.new(0, "x", true).all?.should == true
+      EnumerableSpecs::Numerous.new('a','b','c').should.all?
+      EnumerableSpecs::Numerous.new(0, "x", true).should.all?
     end
 
     it "returns false if there are false or nil elements" do
-      EnumerableSpecs::Numerous.new(false).all?.should == false
-      EnumerableSpecs::Numerous.new(false, false).all?.should == false
+      EnumerableSpecs::Numerous.new(false).should_not.all?
+      EnumerableSpecs::Numerous.new(false, false).should_not.all?
 
-      EnumerableSpecs::Numerous.new(nil).all?.should == false
-      EnumerableSpecs::Numerous.new(nil, nil).all?.should == false
+      EnumerableSpecs::Numerous.new(nil).should_not.all?
+      EnumerableSpecs::Numerous.new(nil, nil).should_not.all?
 
-      EnumerableSpecs::Numerous.new(1, nil, 2).all?.should == false
-      EnumerableSpecs::Numerous.new(0, "x", false, true).all?.should == false
-      @enum2.all?.should == false
+      EnumerableSpecs::Numerous.new(1, nil, 2).should_not.all?
+      EnumerableSpecs::Numerous.new(0, "x", false, true).should_not.all?
+      @enum2.should_not.all?
     end
 
     it "gathers whole arrays as elements when each yields multiple" do
       multi = EnumerableSpecs::YieldsMultiWithFalse.new
-      multi.all?.should be_true
+      multi.all?.should == true
     end
   end
 
@@ -115,7 +106,7 @@ describe "Enumerable#all?" do
     it "does not hide exceptions out of the block" do
       -> {
         @enum.all? { raise "from block" }
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
 
     it "gathers initial args as elements when each yields multiple" do
@@ -133,69 +124,64 @@ describe "Enumerable#all?" do
     end
   end
 
-  ruby_version_is "2.5" do
-    describe 'when given a pattern argument' do
-      it "calls `===` on the pattern the return value " do
-        pattern = EnumerableSpecs::Pattern.new { |x| x >= 0 }
-        @enum1.all?(pattern).should == false
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-      end
-
-      # may raise an exception in future versions
-      ruby_version_is ""..."2.6" do
-        it "ignores block" do
-          @enum2.all?(NilClass) { raise }.should == false
-          [1, 2, nil].all?(NilClass) { raise }.should == false
-          {a: 1}.all?(Array) { raise }.should == true
-        end
-      end
-
-      it "always returns true on empty enumeration" do
-        @empty.all?(Integer).should == true
-        [].all?(Integer).should == true
-        {}.all?(NilClass).should == true
-      end
-
-      it "does not hide exceptions out of #each" do
-        -> {
-          EnumerableSpecs::ThrowingEach.new.all?(Integer)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "returns true if the pattern never returns false or nil" do
-        pattern = EnumerableSpecs::Pattern.new { |x| 42 }
-        @enum.all?(pattern).should == true
-
-        [1, 42, 3].all?(pattern).should == true
-
-        pattern = EnumerableSpecs::Pattern.new { |x| Array === x }
-        {a: 1, b: 2}.all?(pattern).should == true
-      end
-
-      it "returns false if the pattern ever returns false or nil" do
-        pattern = EnumerableSpecs::Pattern.new { |x| x >= 0 }
-        @enum1.all?(pattern).should == false
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-
-        [1, 2, 3, -1].all?(pattern).should == false
-
-        pattern = EnumerableSpecs::Pattern.new { |x| x[1] >= 0 }
-        {a: 1, b: -1}.all?(pattern).should == false
-      end
-
-      it "does not hide exceptions out of pattern#===" do
-        pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
-        -> {
-          @enum.all?(pattern)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "calls the pattern with gathered array when yielded with multiple arguments" do
-        multi = EnumerableSpecs::YieldsMulti.new
-        pattern = EnumerableSpecs::Pattern.new { true }
-        multi.all?(pattern).should == true
-        pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
-      end
+  describe 'when given a pattern argument' do
+    it "calls `===` on the pattern the return value" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x >= 0 }
+      @enum1.all?(pattern).should == false
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+    end
+
+    it "always returns true on empty enumeration" do
+      @empty.all?(Integer).should == true
+      [].all?(Integer).should == true
+      {}.all?(NilClass).should == true
+    end
+
+    it "does not hide exceptions out of #each" do
+      -> {
+        EnumerableSpecs::ThrowingEach.new.all?(Integer)
+      }.should.raise(RuntimeError)
+    end
+
+    it "returns true if the pattern never returns false or nil" do
+      pattern = EnumerableSpecs::Pattern.new { |x| 42 }
+      @enum.all?(pattern).should == true
+
+      [1, 42, 3].all?(pattern).should == true
+
+      pattern = EnumerableSpecs::Pattern.new { |x| Array === x }
+      {a: 1, b: 2}.all?(pattern).should == true
+    end
+
+    it "returns false if the pattern ever returns false or nil" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x >= 0 }
+      @enum1.all?(pattern).should == false
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+
+      [1, 2, 3, -1].all?(pattern).should == false
+
+      pattern = EnumerableSpecs::Pattern.new { |x| x[1] >= 0 }
+      {a: 1, b: -1}.all?(pattern).should == false
+    end
+
+    it "does not hide exceptions out of pattern#===" do
+      pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
+      -> {
+        @enum.all?(pattern)
+      }.should.raise(RuntimeError)
+    end
+
+    it "calls the pattern with gathered array when yielded with multiple arguments" do
+      multi = EnumerableSpecs::YieldsMulti.new
+      pattern = EnumerableSpecs::Pattern.new { true }
+      multi.all?(pattern).should == true
+      pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
+    end
+
+    it "ignores the block if there is an argument" do
+      -> {
+        EnumerableSpecs::Numerous.new(1, 2, 3, 4, 5).all?(String) { true }.should == false
+      }.should complain(/given block not used/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/any_spec.rb b/spec/ruby/core/enumerable/any_spec.rb
index c800fe2d4b..4405d4740a 100644
--- a/spec/ruby/core/enumerable/any_spec.rb
+++ b/spec/ruby/core/enumerable/any_spec.rb
@@ -10,66 +10,57 @@ describe "Enumerable#any?" do
   end
 
   it "always returns false on empty enumeration" do
-    @empty.any?.should == false
+    @empty.should_not.any?
     @empty.any? { nil }.should == false
 
-    [].any?.should == false
+    [].should_not.any?
     [].any? { false }.should == false
 
-    {}.any?.should == false
+    {}.should_not.any?
     {}.any? { nil }.should == false
   end
 
   it "raises an ArgumentError when more than 1 argument is provided" do
-    -> { @enum.any?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { [].any?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { {}.any?(1, 2, 3) }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is ""..."2.5" do
-    it "raises an ArgumentError when any arguments provided" do
-      -> { @enum.any?(Proc.new {}) }.should raise_error(ArgumentError)
-      -> { @enum.any?(nil) }.should raise_error(ArgumentError)
-      -> { @empty.any?(1) }.should raise_error(ArgumentError)
-      -> { @enum1.any?(1) {} }.should raise_error(ArgumentError)
-    end
+    -> { @enum.any?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { [].any?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { {}.any?(1, 2, 3) }.should.raise(ArgumentError)
   end
 
   it "does not hide exceptions out of #each" do
     -> {
       EnumerableSpecs::ThrowingEach.new.any?
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
 
     -> {
       EnumerableSpecs::ThrowingEach.new.any? { false }
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
   end
 
   describe "with no block" do
     it "returns true if any element is not false or nil" do
-      @enum.any?.should == true
-      @enum1.any?.should == true
-      @enum2.any?.should == true
-      EnumerableSpecs::Numerous.new(true).any?.should == true
-      EnumerableSpecs::Numerous.new('a','b','c').any?.should == true
-      EnumerableSpecs::Numerous.new('a','b','c', nil).any?.should == true
-      EnumerableSpecs::Numerous.new(1, nil, 2).any?.should == true
-      EnumerableSpecs::Numerous.new(1, false).any?.should == true
-      EnumerableSpecs::Numerous.new(false, nil, 1, false).any?.should == true
-      EnumerableSpecs::Numerous.new(false, 0, nil).any?.should == true
+      @enum.should.any?
+      @enum1.should.any?
+      @enum2.should.any?
+      EnumerableSpecs::Numerous.new(true).should.any?
+      EnumerableSpecs::Numerous.new('a','b','c').should.any?
+      EnumerableSpecs::Numerous.new('a','b','c', nil).should.any?
+      EnumerableSpecs::Numerous.new(1, nil, 2).should.any?
+      EnumerableSpecs::Numerous.new(1, false).should.any?
+      EnumerableSpecs::Numerous.new(false, nil, 1, false).should.any?
+      EnumerableSpecs::Numerous.new(false, 0, nil).should.any?
     end
 
     it "returns false if all elements are false or nil" do
-      EnumerableSpecs::Numerous.new(false).any?.should == false
-      EnumerableSpecs::Numerous.new(false, false).any?.should == false
-      EnumerableSpecs::Numerous.new(nil).any?.should == false
-      EnumerableSpecs::Numerous.new(nil, nil).any?.should == false
-      EnumerableSpecs::Numerous.new(nil, false, nil).any?.should == false
+      EnumerableSpecs::Numerous.new(false).should_not.any?
+      EnumerableSpecs::Numerous.new(false, false).should_not.any?
+      EnumerableSpecs::Numerous.new(nil).should_not.any?
+      EnumerableSpecs::Numerous.new(nil, nil).should_not.any?
+      EnumerableSpecs::Numerous.new(nil, false, nil).should_not.any?
     end
 
     it "gathers whole arrays as elements when each yields multiple" do
       multi = EnumerableSpecs::YieldsMultiWithFalse.new
-      multi.any?.should be_true
+      multi.any?.should == true
     end
   end
 
@@ -129,7 +120,7 @@ describe "Enumerable#any?" do
     it "does not hide exceptions out of the block" do
       -> {
         @enum.any? { raise "from block" }
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
 
     it "gathers initial args as elements when each yields multiple" do
@@ -147,68 +138,63 @@ describe "Enumerable#any?" do
     end
   end
 
-  ruby_version_is "2.5" do
-    describe 'when given a pattern argument' do
-      it "calls `===` on the pattern the return value " do
-        pattern = EnumerableSpecs::Pattern.new { |x| x == 2 }
-        @enum1.any?(pattern).should == true
-        pattern.yielded.should == [[0], [1], [2]]
-      end
-
-      # may raise an exception in future versions
-      ruby_version_is ""..."2.6" do
-        it "ignores block" do
-          @enum2.any?(NilClass) { raise }.should == true
-          [1, 2, nil].any?(NilClass) { raise }.should == true
-          {a: 1}.any?(Array) { raise }.should == true
-        end
-      end
-
-      it "always returns false on empty enumeration" do
-        @empty.any?(Integer).should == false
-        [].any?(Integer).should == false
-        {}.any?(NilClass).should == false
-      end
-
-      it "does not hide exceptions out of #each" do
-        -> {
-          EnumerableSpecs::ThrowingEach.new.any?(Integer)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "returns true if the pattern ever returns a truthy value" do
-        @enum2.any?(NilClass).should == true
-        pattern = EnumerableSpecs::Pattern.new { |x| 42 }
-        @enum.any?(pattern).should == true
-
-        [1, 42, 3].any?(pattern).should == true
-
-        pattern = EnumerableSpecs::Pattern.new { |x| x == [:b, 2] }
-        {a: 1, b: 2}.any?(pattern).should == true
-      end
-
-      it "returns false if the block never returns other than false or nil" do
-        pattern = EnumerableSpecs::Pattern.new { |x| nil }
-        @enum1.any?(pattern).should == false
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-
-        [1, 2, 3].any?(pattern).should == false
-        {a: 1}.any?(pattern).should == false
-      end
-
-      it "does not hide exceptions out of pattern#===" do
-        pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
-        -> {
-          @enum.any?(pattern)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "calls the pattern with gathered array when yielded with multiple arguments" do
-        multi = EnumerableSpecs::YieldsMulti.new
-        pattern = EnumerableSpecs::Pattern.new { false }
-        multi.any?(pattern).should == false
-        pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
-      end
+  describe 'when given a pattern argument' do
+    it "calls `===` on the pattern the return value" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x == 2 }
+      @enum1.any?(pattern).should == true
+      pattern.yielded.should == [[0], [1], [2]]
+    end
+
+    it "always returns false on empty enumeration" do
+      @empty.any?(Integer).should == false
+      [].any?(Integer).should == false
+      {}.any?(NilClass).should == false
+    end
+
+    it "does not hide exceptions out of #each" do
+      -> {
+        EnumerableSpecs::ThrowingEach.new.any?(Integer)
+      }.should.raise(RuntimeError)
+    end
+
+    it "returns true if the pattern ever returns a truthy value" do
+      @enum2.any?(NilClass).should == true
+      pattern = EnumerableSpecs::Pattern.new { |x| 42 }
+      @enum.any?(pattern).should == true
+
+      [1, 42, 3].any?(pattern).should == true
+
+      pattern = EnumerableSpecs::Pattern.new { |x| x == [:b, 2] }
+      {a: 1, b: 2}.any?(pattern).should == true
+    end
+
+    it "returns false if the block never returns other than false or nil" do
+      pattern = EnumerableSpecs::Pattern.new { |x| nil }
+      @enum1.any?(pattern).should == false
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+
+      [1, 2, 3].any?(pattern).should == false
+      {a: 1}.any?(pattern).should == false
+    end
+
+    it "does not hide exceptions out of pattern#===" do
+      pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
+      -> {
+        @enum.any?(pattern)
+      }.should.raise(RuntimeError)
+    end
+
+    it "calls the pattern with gathered array when yielded with multiple arguments" do
+      multi = EnumerableSpecs::YieldsMulti.new
+      pattern = EnumerableSpecs::Pattern.new { false }
+      multi.any?(pattern).should == false
+      pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
+    end
+
+    it "ignores the block if there is an argument" do
+      -> {
+        EnumerableSpecs::Numerous.new(1, 2, 3, 4, 5).any?(String) { true }.should == false
+      }.should complain(/given block not used/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/chain_spec.rb b/spec/ruby/core/enumerable/chain_spec.rb
index 85c0c03603..a0597e46a1 100644
--- a/spec/ruby/core/enumerable/chain_spec.rb
+++ b/spec/ruby/core/enumerable/chain_spec.rb
@@ -1,25 +1,23 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerable#chain" do
-    before :each do
-      ScratchPad.record []
-    end
+describe "Enumerable#chain" do
+  before :each do
+    ScratchPad.record []
+  end
 
-    it "returns a chain of self and provided enumerables" do
-      one = EnumerableSpecs::Numerous.new(1)
-      two = EnumerableSpecs::Numerous.new(2, 3)
-      three = EnumerableSpecs::Numerous.new(4, 5, 6)
+  it "returns a chain of self and provided enumerables" do
+    one = EnumerableSpecs::Numerous.new(1)
+    two = EnumerableSpecs::Numerous.new(2, 3)
+    three = EnumerableSpecs::Numerous.new(4, 5, 6)
 
-      chain = one.chain(two, three)
+    chain = one.chain(two, three)
 
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 2, 3, 4, 5, 6]
-    end
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 2, 3, 4, 5, 6]
+  end
 
-    it "returns an Enumerator::Chain if given a block" do
-      EnumerableSpecs::Numerous.new.chain.should be_an_instance_of(Enumerator::Chain)
-    end
+  it "returns an Enumerator::Chain if given a block" do
+    EnumerableSpecs::Numerous.new.chain.should.instance_of?(Enumerator::Chain)
   end
 end
diff --git a/spec/ruby/core/enumerable/chunk_spec.rb b/spec/ruby/core/enumerable/chunk_spec.rb
index 548544f4e8..7c9b31c991 100644
--- a/spec/ruby/core/enumerable/chunk_spec.rb
+++ b/spec/ruby/core/enumerable/chunk_spec.rb
@@ -8,13 +8,13 @@ describe "Enumerable#chunk" do
 
   it "returns an Enumerator if called without a block" do
     chunk = EnumerableSpecs::Numerous.new(1, 2, 3, 1, 2).chunk
-    chunk.should be_an_instance_of(Enumerator)
+    chunk.should.instance_of?(Enumerator)
     result = chunk.with_index {|elt, i| elt - i }.to_a
     result.should == [[1, [1, 2, 3]], [-2, [1, 2]]]
   end
 
   it "returns an Enumerator if given a block" do
-    EnumerableSpecs::Numerous.new.chunk {}.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new.chunk {}.should.instance_of?(Enumerator)
   end
 
   it "yields the current element and the current chunk to the block" do
@@ -29,12 +29,22 @@ describe "Enumerable#chunk" do
     result.should == [[1, [1, 2]], [0, [3]], [1, [2]], [0, [3]], [1, [2, 1]]]
   end
 
+  it "returns a partitioned Array of values" do
+    e = EnumerableSpecs::Numerous.new(1,2,3)
+    e.chunk { |x| x > 2 }.map(&:last).should == [[1, 2], [3]]
+  end
+
   it "returns elements for which the block returns :_alone in separate Arrays" do
     e = EnumerableSpecs::Numerous.new(1, 2, 3, 2, 1)
     result = e.chunk { |x| x < 2 && :_alone }.to_a
     result.should == [[:_alone, [1]], [false, [2, 3, 2]], [:_alone, [1]]]
   end
 
+  it "yields Arrays as a single argument to a rest argument" do
+    e = EnumerableSpecs::Numerous.new([1, 2])
+    result = e.chunk { |*x| x.should == [[1,2]] }.to_a
+  end
+
   it "does not return elements for which the block returns :_separator" do
     e = EnumerableSpecs::Numerous.new(1, 2, 3, 3, 2, 1)
     result = e.chunk { |x| x == 2 ? :_separator : 1 }.to_a
@@ -49,14 +59,14 @@ describe "Enumerable#chunk" do
 
   it "raises a RuntimeError if the block returns a Symbol starting with an underscore other than :_alone or :_separator" do
     e = EnumerableSpecs::Numerous.new(1, 2, 3, 2, 1)
-    -> { e.chunk { |x| :_arbitrary }.to_a }.should raise_error(RuntimeError)
+    -> { e.chunk { |x| :_arbitrary }.to_a }.should.raise(RuntimeError)
   end
 
   it "does not accept arguments" do
     e = EnumerableSpecs::Numerous.new(1, 2, 3)
     -> {
       e.chunk(1) {}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it 'returned Enumerator size returns nil' do
diff --git a/spec/ruby/core/enumerable/chunk_while_spec.rb b/spec/ruby/core/enumerable/chunk_while_spec.rb
index 26bcc983db..286f717442 100644
--- a/spec/ruby/core/enumerable/chunk_while_spec.rb
+++ b/spec/ruby/core/enumerable/chunk_while_spec.rb
@@ -11,7 +11,7 @@ describe "Enumerable#chunk_while" do
 
   context "when given a block" do
     it "returns an enumerator" do
-      @result.should be_an_instance_of(Enumerator)
+      @result.should.instance_of?(Enumerator)
     end
 
     it "splits chunks between adjacent elements i and j where the block returns false" do
@@ -30,7 +30,7 @@ describe "Enumerable#chunk_while" do
 
   context "when not given a block" do
     it "raises an ArgumentError" do
-      -> { @enum.chunk_while }.should raise_error(ArgumentError)
+      -> { @enum.chunk_while }.should.raise(ArgumentError)
     end
   end
 
diff --git a/spec/ruby/core/enumerable/collect_concat_spec.rb b/spec/ruby/core/enumerable/collect_concat_spec.rb
index 6e34c9eb93..59317cfe34 100644
--- a/spec/ruby/core/enumerable/collect_concat_spec.rb
+++ b/spec/ruby/core/enumerable/collect_concat_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/collect_concat'
 
 describe "Enumerable#collect_concat" do
-  it_behaves_like :enumerable_collect_concat , :collect_concat
+  it_behaves_like :enumerable_collect_concat, :collect_concat
 end
diff --git a/spec/ruby/core/enumerable/collect_spec.rb b/spec/ruby/core/enumerable/collect_spec.rb
index 1016b67798..cfa2895cce 100644
--- a/spec/ruby/core/enumerable/collect_spec.rb
+++ b/spec/ruby/core/enumerable/collect_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/collect'
 
 describe "Enumerable#collect" do
-  it_behaves_like :enumerable_collect , :collect
+  it_behaves_like :enumerable_collect, :collect
 end
diff --git a/spec/ruby/core/enumerable/compact_spec.rb b/spec/ruby/core/enumerable/compact_spec.rb
new file mode 100644
index 0000000000..1895430c4e
--- /dev/null
+++ b/spec/ruby/core/enumerable/compact_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Enumerable#compact" do
+  it 'returns array without nil elements' do
+    arr = EnumerableSpecs::Numerous.new(nil, 1, 2, nil, true)
+    arr.compact.should == [1, 2, true]
+  end
+end
diff --git a/spec/ruby/core/enumerable/cycle_spec.rb b/spec/ruby/core/enumerable/cycle_spec.rb
index 487086cba3..1fb3cc3d41 100644
--- a/spec/ruby/core/enumerable/cycle_spec.rb
+++ b/spec/ruby/core/enumerable/cycle_spec.rb
@@ -17,7 +17,7 @@ describe "Enumerable#cycle" do
 
     it "returns nil if there are no elements" do
       out = EnumerableSpecs::Empty.new.cycle { break :nope }
-      out.should be_nil
+      out.should == nil
     end
 
     it "yields successive elements of the array repeatedly" do
@@ -44,8 +44,8 @@ describe "Enumerable#cycle" do
 
   describe "passed a number n as an argument" do
     it "returns nil and does nothing for non positive n" do
-      EnumerableSpecs::ThrowingEach.new.cycle(0) {}.should be_nil
-      EnumerableSpecs::NoEach.new.cycle(-22) {}.should be_nil
+      EnumerableSpecs::ThrowingEach.new.cycle(0) {}.should == nil
+      EnumerableSpecs::NoEach.new.cycle(-22) {}.should == nil
     end
 
     it "calls each at most once" do
@@ -71,12 +71,12 @@ describe "Enumerable#cycle" do
 
     it "raises a TypeError when the passed n cannot be coerced to Integer" do
       enum = EnumerableSpecs::Numerous.new
-      ->{ enum.cycle("cat"){} }.should raise_error(TypeError)
+      ->{ enum.cycle("cat"){} }.should.raise(TypeError)
     end
 
     it "raises an ArgumentError if more arguments are passed" do
       enum = EnumerableSpecs::Numerous.new
-      ->{ enum.cycle(1, 2) {} }.should raise_error(ArgumentError)
+      ->{ enum.cycle(1, 2) {} }.should.raise(ArgumentError)
     end
 
     it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/detect_spec.rb b/spec/ruby/core/enumerable/detect_spec.rb
index e912134fed..6959aadc44 100644
--- a/spec/ruby/core/enumerable/detect_spec.rb
+++ b/spec/ruby/core/enumerable/detect_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/find'
 
 describe "Enumerable#detect" do
-  it_behaves_like :enumerable_find , :detect
+  it_behaves_like :enumerable_find, :detect
 end
diff --git a/spec/ruby/core/enumerable/drop_spec.rb b/spec/ruby/core/enumerable/drop_spec.rb
index 423cc0088b..8d95f464b3 100644
--- a/spec/ruby/core/enumerable/drop_spec.rb
+++ b/spec/ruby/core/enumerable/drop_spec.rb
@@ -7,13 +7,13 @@ describe "Enumerable#drop" do
   end
 
   it "requires exactly one argument" do
-    ->{ @enum.drop{} }.should raise_error(ArgumentError)
-    ->{ @enum.drop(1, 2){} }.should raise_error(ArgumentError)
+    ->{ @enum.drop{} }.should.raise(ArgumentError)
+    ->{ @enum.drop(1, 2){} }.should.raise(ArgumentError)
   end
 
   describe "passed a number n as an argument" do
     it "raises ArgumentError if n < 0" do
-      ->{ @enum.drop(-1) }.should raise_error(ArgumentError)
+      ->{ @enum.drop(-1) }.should.raise(ArgumentError)
     end
 
     it "tries to convert n to an Integer using #to_int" do
@@ -35,8 +35,8 @@ describe "Enumerable#drop" do
     end
 
     it "raises a TypeError when the passed n cannot be coerced to Integer" do
-      ->{ @enum.drop("hat") }.should raise_error(TypeError)
-      ->{ @enum.drop(nil) }.should raise_error(TypeError)
+      ->{ @enum.drop("hat") }.should.raise(TypeError)
+      ->{ @enum.drop(nil) }.should.raise(TypeError)
     end
 
   end
diff --git a/spec/ruby/core/enumerable/drop_while_spec.rb b/spec/ruby/core/enumerable/drop_while_spec.rb
index 636c3d284a..4b4fdf2d4f 100644
--- a/spec/ruby/core/enumerable/drop_while_spec.rb
+++ b/spec/ruby/core/enumerable/drop_while_spec.rb
@@ -8,7 +8,7 @@ describe "Enumerable#drop_while" do
   end
 
   it "returns an Enumerator if no block given" do
-    @enum.drop_while.should be_an_instance_of(Enumerator)
+    @enum.drop_while.should.instance_of?(Enumerator)
   end
 
   it "returns no/all elements for {true/false} block" do
@@ -38,7 +38,7 @@ describe "Enumerable#drop_while" do
 
   it "doesn't return self when it could" do
     a = [1,2,3]
-    a.drop_while{false}.should_not equal(a)
+    a.drop_while{false}.should_not.equal?(a)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/each_cons_spec.rb b/spec/ruby/core/enumerable/each_cons_spec.rb
index 7d44f54f74..c5e299fd00 100644
--- a/spec/ruby/core/enumerable/each_cons_spec.rb
+++ b/spec/ruby/core/enumerable/each_cons_spec.rb
@@ -10,24 +10,24 @@ describe "Enumerable#each_cons" do
 
   it "passes element groups to the block" do
     acc = []
-    @enum.each_cons(3){|g| acc << g}.should be_nil
+    @enum.each_cons(3){|g| acc << g}
     acc.should == @in_threes
   end
 
   it "raises an ArgumentError if there is not a single parameter > 0" do
-    ->{ @enum.each_cons(0){}    }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons(-2){}   }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons{}       }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons(2,2){}  }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons(0)      }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons(-2)     }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons         }.should raise_error(ArgumentError)
-    ->{ @enum.each_cons(2,2)    }.should raise_error(ArgumentError)
+    ->{ @enum.each_cons(0){}    }.should.raise(ArgumentError)
+    ->{ @enum.each_cons(-2){}   }.should.raise(ArgumentError)
+    ->{ @enum.each_cons{}       }.should.raise(ArgumentError)
+    ->{ @enum.each_cons(2,2){}  }.should.raise(ArgumentError)
+    ->{ @enum.each_cons(0)      }.should.raise(ArgumentError)
+    ->{ @enum.each_cons(-2)     }.should.raise(ArgumentError)
+    ->{ @enum.each_cons         }.should.raise(ArgumentError)
+    ->{ @enum.each_cons(2,2)    }.should.raise(ArgumentError)
   end
 
   it "tries to convert n to an Integer using #to_int" do
     acc = []
-    @enum.each_cons(3.3){|g| acc << g}.should == nil
+    @enum.each_cons(3.3){|g| acc << g}
     acc.should == @in_threes
 
     obj = mock('to_int')
@@ -56,10 +56,14 @@ describe "Enumerable#each_cons" do
     multi.each_cons(2).to_a.should == [[[1, 2], [3, 4, 5]], [[3, 4, 5], [6, 7, 8, 9]]]
   end
 
+  it "returns self when a block is given" do
+    @enum.each_cons(3){}.should == @enum
+  end
+
   describe "when no block is given" do
     it "returns an enumerator" do
       e = @enum.each_cons(3)
-      e.should be_an_instance_of(Enumerator)
+      e.should.instance_of?(Enumerator)
       e.to_a.should == @in_threes
     end
 
diff --git a/spec/ruby/core/enumerable/each_entry_spec.rb b/spec/ruby/core/enumerable/each_entry_spec.rb
index edf00f3137..9dc89ec28e 100644
--- a/spec/ruby/core/enumerable/each_entry_spec.rb
+++ b/spec/ruby/core/enumerable/each_entry_spec.rb
@@ -11,13 +11,13 @@ describe "Enumerable#each_entry" do
 
   it "yields multiple arguments as an array" do
     acc = []
-    @enum.each_entry {|g| acc << g}.should equal(@enum)
+    @enum.each_entry {|g| acc << g}.should.equal?(@enum)
     acc.should == @entries
   end
 
   it "returns an enumerator if no block" do
     e = @enum.each_entry
-    e.should be_an_instance_of(Enumerator)
+    e.should.instance_of?(Enumerator)
     e.to_a.should == @entries
   end
 
@@ -27,8 +27,8 @@ describe "Enumerable#each_entry" do
   end
 
   it "raises an ArgumentError when extra arguments" do
-    -> { @enum.each_entry("one").to_a   }.should raise_error(ArgumentError)
-    -> { @enum.each_entry("one"){}.to_a }.should raise_error(ArgumentError)
+    -> { @enum.each_entry("one").to_a   }.should.raise(ArgumentError)
+    -> { @enum.each_entry("one"){}.to_a }.should.raise(ArgumentError)
   end
 
   it "passes extra arguments to #each" do
diff --git a/spec/ruby/core/enumerable/each_slice_spec.rb b/spec/ruby/core/enumerable/each_slice_spec.rb
index ab3b79c344..d05abad1e9 100644
--- a/spec/ruby/core/enumerable/each_slice_spec.rb
+++ b/spec/ruby/core/enumerable/each_slice_spec.rb
@@ -10,24 +10,24 @@ describe "Enumerable#each_slice" do
 
   it "passes element groups to the block" do
     acc = []
-    @enum.each_slice(3){|g| acc << g}.should be_nil
+    @enum.each_slice(3){|g| acc << g}
     acc.should == @sliced
   end
 
   it "raises an ArgumentError if there is not a single parameter > 0" do
-    ->{ @enum.each_slice(0){}    }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice(-2){}   }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice{}       }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice(2,2){}  }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice(0)      }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice(-2)     }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice         }.should raise_error(ArgumentError)
-    ->{ @enum.each_slice(2,2)    }.should raise_error(ArgumentError)
+    ->{ @enum.each_slice(0){}    }.should.raise(ArgumentError)
+    ->{ @enum.each_slice(-2){}   }.should.raise(ArgumentError)
+    ->{ @enum.each_slice{}       }.should.raise(ArgumentError)
+    ->{ @enum.each_slice(2,2){}  }.should.raise(ArgumentError)
+    ->{ @enum.each_slice(0)      }.should.raise(ArgumentError)
+    ->{ @enum.each_slice(-2)     }.should.raise(ArgumentError)
+    ->{ @enum.each_slice         }.should.raise(ArgumentError)
+    ->{ @enum.each_slice(2,2)    }.should.raise(ArgumentError)
   end
 
   it "tries to convert n to an Integer using #to_int" do
     acc = []
-    @enum.each_slice(3.3){|g| acc << g}.should == nil
+    @enum.each_slice(3.3){|g| acc << g}
     acc.should == @sliced
 
     obj = mock('to_int')
@@ -53,10 +53,14 @@ describe "Enumerable#each_slice" do
 
   it "returns an enumerator if no block" do
     e = @enum.each_slice(3)
-    e.should be_an_instance_of(Enumerator)
+    e.should.instance_of?(Enumerator)
     e.to_a.should == @sliced
   end
 
+  it "returns self when a block is given" do
+    @enum.each_slice(3){}.should == @enum
+  end
+
   it "gathers whole arrays as elements when each yields multiple" do
     multi = EnumerableSpecs::YieldsMulti.new
     multi.each_slice(2).to_a.should == [[[1, 2], [3, 4, 5]], [[6, 7, 8, 9]]]
@@ -65,7 +69,7 @@ describe "Enumerable#each_slice" do
   describe "when no block is given" do
     it "returns an enumerator" do
       e = @enum.each_slice(3)
-      e.should be_an_instance_of(Enumerator)
+      e.should.instance_of?(Enumerator)
       e.to_a.should == @sliced
     end
 
diff --git a/spec/ruby/core/enumerable/each_with_index_spec.rb b/spec/ruby/core/enumerable/each_with_index_spec.rb
index 122e88eab7..fcb2f82f84 100644
--- a/spec/ruby/core/enumerable/each_with_index_spec.rb
+++ b/spec/ruby/core/enumerable/each_with_index_spec.rb
@@ -26,19 +26,19 @@ describe "Enumerable#each_with_index" do
     acc = []
     res = @b.each_with_index {|a,i| acc << [a,i]}
     [[2, 0], [5, 1], [3, 2], [6, 3], [1, 4], [4, 5]].should == acc
-    res.should eql(@b)
+    res.should.eql?(@b)
   end
 
   it "binds splat arguments properly" do
     acc = []
     res = @b.each_with_index { |*b| c,d = b; acc << c; acc << d }
     [2, 0, 5, 1, 3, 2, 6, 3, 1, 4, 4, 5].should == acc
-    res.should eql(@b)
+    res.should.eql?(@b)
   end
 
   it "returns an enumerator if no block" do
     e = @b.each_with_index
-    e.should be_an_instance_of(Enumerator)
+    e.should.instance_of?(Enumerator)
     e.to_a.should == [[2, 0], [5, 1], [3, 2], [6, 3], [1, 4], [4, 5]]
   end
 
diff --git a/spec/ruby/core/enumerable/each_with_object_spec.rb b/spec/ruby/core/enumerable/each_with_object_spec.rb
index 35665e7019..1760d3b267 100644
--- a/spec/ruby/core/enumerable/each_with_object_spec.rb
+++ b/spec/ruby/core/enumerable/each_with_object_spec.rb
@@ -12,10 +12,10 @@ describe "Enumerable#each_with_object" do
   it "passes each element and its argument to the block" do
     acc = []
     @enum.each_with_object(@initial) do |elem, obj|
-      obj.should equal(@initial)
+      obj.should.equal?(@initial)
       obj = 42
       acc << elem
-    end.should equal(@initial)
+    end.should.equal?(@initial)
     acc.should == @values
   end
 
@@ -23,10 +23,10 @@ describe "Enumerable#each_with_object" do
     acc = []
     e = @enum.each_with_object(@initial)
     e.each do |elem, obj|
-      obj.should equal(@initial)
+      obj.should.equal?(@initial)
       obj = 42
       acc << elem
-    end.should equal(@initial)
+    end.should.equal?(@initial)
     acc.should == @values
   end
 
diff --git a/spec/ruby/core/enumerable/entries_spec.rb b/spec/ruby/core/enumerable/entries_spec.rb
index 83232cfa06..2de4fc756a 100644
--- a/spec/ruby/core/enumerable/entries_spec.rb
+++ b/spec/ruby/core/enumerable/entries_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/entries'
 
 describe "Enumerable#entries" do
-  it_behaves_like :enumerable_entries , :entries
+  it_behaves_like :enumerable_entries, :entries
 end
diff --git a/spec/ruby/core/enumerable/filter_map_spec.rb b/spec/ruby/core/enumerable/filter_map_spec.rb
index 31acc277b4..1ed131a960 100644
--- a/spec/ruby/core/enumerable/filter_map_spec.rb
+++ b/spec/ruby/core/enumerable/filter_map_spec.rb
@@ -1,26 +1,24 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is '2.7' do
-  describe 'Enumerable#filter_map' do
-    before :each do
-      @numerous = EnumerableSpecs::Numerous.new(*(1..8).to_a)
-    end
+describe 'Enumerable#filter_map' do
+  before :each do
+    @numerous = EnumerableSpecs::Numerous.new(*(1..8).to_a)
+  end
 
-    it 'returns an empty array if there are no elements' do
-      EnumerableSpecs::Empty.new.filter_map { true }.should == []
-    end
+  it 'returns an empty array if there are no elements' do
+    EnumerableSpecs::Empty.new.filter_map { true }.should == []
+  end
 
-    it 'returns an array with truthy results of passing each element to block' do
-      @numerous.filter_map { |i| i * 2 if i.even? }.should == [4, 8, 12, 16]
-      @numerous.filter_map { |i| i * 2 }.should == [2, 4, 6, 8, 10, 12, 14, 16]
-      @numerous.filter_map { 0 }.should == [0, 0, 0, 0, 0, 0, 0, 0]
-      @numerous.filter_map { false }.should == []
-      @numerous.filter_map { nil }.should == []
-    end
+  it 'returns an array with truthy results of passing each element to block' do
+    @numerous.filter_map { |i| i * 2 if i.even? }.should == [4, 8, 12, 16]
+    @numerous.filter_map { |i| i * 2 }.should == [2, 4, 6, 8, 10, 12, 14, 16]
+    @numerous.filter_map { 0 }.should == [0, 0, 0, 0, 0, 0, 0, 0]
+    @numerous.filter_map { false }.should == []
+    @numerous.filter_map { nil }.should == []
+  end
 
-    it 'returns an enumerator when no block given' do
-      @numerous.filter_map.should be_an_instance_of(Enumerator)
-    end
+  it 'returns an enumerator when no block given' do
+    @numerous.filter_map.should.instance_of?(Enumerator)
   end
 end
diff --git a/spec/ruby/core/enumerable/filter_spec.rb b/spec/ruby/core/enumerable/filter_spec.rb
index f2dc7a7b71..1c3a7e9ff5 100644
--- a/spec/ruby/core/enumerable/filter_spec.rb
+++ b/spec/ruby/core/enumerable/filter_spec.rb
@@ -2,8 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/find_all'
 
-ruby_version_is "2.6" do
-  describe "Enumerable#filter" do
-    it_behaves_like(:enumerable_find_all , :filter)
-  end
+describe "Enumerable#filter" do
+  it_behaves_like :enumerable_find_all, :filter
 end
diff --git a/spec/ruby/core/enumerable/find_all_spec.rb b/spec/ruby/core/enumerable/find_all_spec.rb
index ce9058fe77..9cd635f247 100644
--- a/spec/ruby/core/enumerable/find_all_spec.rb
+++ b/spec/ruby/core/enumerable/find_all_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/find_all'
 
 describe "Enumerable#find_all" do
-  it_behaves_like :enumerable_find_all , :find_all
+  it_behaves_like :enumerable_find_all, :find_all
 end
diff --git a/spec/ruby/core/enumerable/find_index_spec.rb b/spec/ruby/core/enumerable/find_index_spec.rb
index 542660fe04..2e714367ba 100644
--- a/spec/ruby/core/enumerable/find_index_spec.rb
+++ b/spec/ruby/core/enumerable/find_index_spec.rb
@@ -47,7 +47,7 @@ describe "Enumerable#find_index" do
   end
 
   it "returns an Enumerator if no block given" do
-    @numerous.find_index.should be_an_instance_of(Enumerator)
+    @numerous.find_index.should.instance_of?(Enumerator)
   end
 
   it "uses #== for testing equality" do
diff --git a/spec/ruby/core/enumerable/find_spec.rb b/spec/ruby/core/enumerable/find_spec.rb
index 25aa3bf103..5ddebc05f8 100644
--- a/spec/ruby/core/enumerable/find_spec.rb
+++ b/spec/ruby/core/enumerable/find_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/find'
 
 describe "Enumerable#find" do
-  it_behaves_like :enumerable_find , :find
+  it_behaves_like :enumerable_find, :find
 end
diff --git a/spec/ruby/core/enumerable/first_spec.rb b/spec/ruby/core/enumerable/first_spec.rb
index ed1ba599b4..592dff1ebc 100644
--- a/spec/ruby/core/enumerable/first_spec.rb
+++ b/spec/ruby/core/enumerable/first_spec.rb
@@ -19,7 +19,7 @@ describe "Enumerable#first" do
 
   it "raises a RangeError when passed a Bignum" do
     enum = EnumerableSpecs::Empty.new
-    -> { enum.first(bignum_value) }.should raise_error(RangeError)
+    -> { enum.first(bignum_value) }.should.raise(RangeError)
   end
 
   describe "when passed an argument" do
diff --git a/spec/ruby/core/enumerable/fixtures/classes.rb b/spec/ruby/core/enumerable/fixtures/classes.rb
index 5051196742..b5feafcfb7 100644
--- a/spec/ruby/core/enumerable/fixtures/classes.rb
+++ b/spec/ruby/core/enumerable/fixtures/classes.rb
@@ -38,12 +38,14 @@ module EnumerableSpecs
   class Empty
     include Enumerable
     def each
+      self
     end
   end
 
   class EmptyWithSize
     include Enumerable
     def each
+      self
     end
     def size
       0
@@ -251,7 +253,7 @@ module EnumerableSpecs
     end
   end
 
-  class ComparableWithFixnum
+  class ComparableWithInteger
     include Comparable
     def initialize(num)
       @num = num
@@ -342,4 +344,7 @@ module EnumerableSpecs
       @block.call(*args)
     end
   end
+
+  class SetSubclass < Set
+  end
 end # EnumerableSpecs utility classes
diff --git a/spec/ruby/core/enumerable/flat_map_spec.rb b/spec/ruby/core/enumerable/flat_map_spec.rb
index a294b9ddad..bd07eab6c5 100644
--- a/spec/ruby/core/enumerable/flat_map_spec.rb
+++ b/spec/ruby/core/enumerable/flat_map_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/collect_concat'
 
 describe "Enumerable#flat_map" do
-  it_behaves_like :enumerable_collect_concat , :flat_map
+  it_behaves_like :enumerable_collect_concat, :flat_map
 end
diff --git a/spec/ruby/core/enumerable/grep_spec.rb b/spec/ruby/core/enumerable/grep_spec.rb
index c9c0f34e27..965e183766 100644
--- a/spec/ruby/core/enumerable/grep_spec.rb
+++ b/spec/ruby/core/enumerable/grep_spec.rb
@@ -40,15 +40,28 @@ describe "Enumerable#grep" do
     $~.should == nil
   end
 
-  it "sets $~ to the last match when given no block" do
+  it "does not set $~ when given no block" do
     "z" =~ /z/ # Reset $~
     ["abc", "def"].grep(/b/).should == ["abc"]
+    $&.should == "z"
+  end
 
-    # Set by the failed match of "def"
-    $~.should == nil
+  it "does not modify Regexp.last_match without block" do
+    "z" =~ /z/ # Reset last match
+    ["abc", "def"].grep(/b/).should == ["abc"]
+    Regexp.last_match[0].should == "z"
+  end
+
+  it "correctly handles non-string elements" do
+    'set last match' =~ /set last (.*)/
+    [:a, 'b', 'z', :c, 42, nil].grep(/[a-d]/).should == [:a, 'b', :c]
+    $1.should == 'match'
 
-    ["abc", "def"].grep(/e/)
-    $&.should == "e"
+    o = Object.new
+    def o.to_str
+      'hello'
+    end
+    [o].grep(/ll/).first.should.equal?(o)
   end
 
   describe "with a block" do
@@ -68,7 +81,7 @@ describe "Enumerable#grep" do
     end
 
     it "raises an ArgumentError when not given a pattern" do
-      -> { @numerous.grep { |e| e } }.should raise_error(ArgumentError)
+      -> { @numerous.grep { |e| e } }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/grep_v_spec.rb b/spec/ruby/core/enumerable/grep_v_spec.rb
index 6dec487065..ee99a77ac1 100644
--- a/spec/ruby/core/enumerable/grep_v_spec.rb
+++ b/spec/ruby/core/enumerable/grep_v_spec.rb
@@ -20,15 +20,28 @@ describe "Enumerable#grep_v" do
     $&.should == "e"
   end
 
-  it "sets $~ to the last match when given no block" do
+  it "does not set $~ when given no block" do
     "z" =~ /z/ # Reset $~
     ["abc", "def"].grep_v(/e/).should == ["abc"]
+    $&.should == "z"
+  end
 
-    # Set by the match of "def"
-    $&.should == "e"
+  it "does not modify Regexp.last_match without block" do
+    "z" =~ /z/ # Reset last match
+    ["abc", "def"].grep_v(/e/).should == ["abc"]
+    Regexp.last_match[0].should == "z"
+  end
+
+  it "correctly handles non-string elements" do
+    'set last match' =~ /set last (.*)/
+    [:a, 'b', 'z', :c, 42, nil].grep_v(/[a-d]/).should == ['z', 42, nil]
+    $1.should == 'match'
 
-    ["abc", "def"].grep_v(/b/)
-    $&.should == nil
+    o = Object.new
+    def o.to_str
+      'hello'
+    end
+    [o].grep_v(/mm/).first.should.equal?(o)
   end
 
   describe "without block" do
@@ -42,7 +55,7 @@ describe "Enumerable#grep_v" do
     end
 
     it "raises an ArgumentError when not given a pattern" do
-      -> { @numerous.grep_v }.should raise_error(ArgumentError)
+      -> { @numerous.grep_v }.should.raise(ArgumentError)
     end
   end
 
@@ -57,7 +70,7 @@ describe "Enumerable#grep_v" do
     end
 
     it "raises an ArgumentError when not given a pattern" do
-      -> { @numerous.grep_v { |e| e } }.should raise_error(ArgumentError)
+      -> { @numerous.grep_v { |e| e } }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/group_by_spec.rb b/spec/ruby/core/enumerable/group_by_spec.rb
index 580a90cf0c..904e5d6c68 100644
--- a/spec/ruby/core/enumerable/group_by_spec.rb
+++ b/spec/ruby/core/enumerable/group_by_spec.rb
@@ -16,13 +16,13 @@ describe "Enumerable#group_by" do
   it "returns a hash without default_proc" do
     e = EnumerableSpecs::Numerous.new("foo", "bar", "baz")
     h = e.group_by { |word| word[0..0].to_sym }
-    h[:some].should be_nil
-    h.default_proc.should be_nil
-    h.default.should be_nil
+    h[:some].should == nil
+    h.default_proc.should == nil
+    h.default.should == nil
   end
 
   it "returns an Enumerator if called without a block" do
-    EnumerableSpecs::Numerous.new.group_by.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new.group_by.should.instance_of?(Enumerator)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
@@ -33,13 +33,5 @@ describe "Enumerable#group_by" do
                   [3, 4, 5] => [[3, 4, 5]] }
   end
 
-  it "returns a tainted hash if self is tainted" do
-    EnumerableSpecs::Empty.new.taint.group_by {}.tainted?.should be_true
-  end
-
-  it "returns an untrusted hash if self is untrusted" do
-    EnumerableSpecs::Empty.new.untrust.group_by {}.untrusted?.should be_true
-  end
-
   it_behaves_like :enumerable_enumeratorized_with_origin_size, :group_by
 end
diff --git a/spec/ruby/core/enumerable/lazy_spec.rb b/spec/ruby/core/enumerable/lazy_spec.rb
index 9a9ead81a0..935e574067 100644
--- a/spec/ruby/core/enumerable/lazy_spec.rb
+++ b/spec/ruby/core/enumerable/lazy_spec.rb
@@ -5,6 +5,6 @@ require_relative 'fixtures/classes'
 
 describe "Enumerable#lazy" do
   it "returns an instance of Enumerator::Lazy" do
-    EnumerableSpecs::Numerous.new.lazy.should be_an_instance_of(Enumerator::Lazy)
+    EnumerableSpecs::Numerous.new.lazy.should.instance_of?(Enumerator::Lazy)
   end
 end
diff --git a/spec/ruby/core/enumerable/map_spec.rb b/spec/ruby/core/enumerable/map_spec.rb
index d65aec238c..98a70781cf 100644
--- a/spec/ruby/core/enumerable/map_spec.rb
+++ b/spec/ruby/core/enumerable/map_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/collect'
 
 describe "Enumerable#map" do
-  it_behaves_like :enumerable_collect , :map
+  it_behaves_like :enumerable_collect, :map
 end
diff --git a/spec/ruby/core/enumerable/max_by_spec.rb b/spec/ruby/core/enumerable/max_by_spec.rb
index ec1738ea3b..f67b5d15ea 100644
--- a/spec/ruby/core/enumerable/max_by_spec.rb
+++ b/spec/ruby/core/enumerable/max_by_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/enumerable_enumeratorized'
 
 describe "Enumerable#max_by" do
   it "returns an enumerator if no block" do
-    EnumerableSpecs::Numerous.new(42).max_by.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new(42).max_by.should.instance_of?(Enumerator)
   end
 
   it "returns nil if #each yields no objects" do
@@ -18,7 +18,7 @@ describe "Enumerable#max_by" do
 
   it "returns the object that appears first in #each in case of a tie" do
     a, b, c = '1', '2', '2'
-    EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj.to_i }.should equal(b)
+    EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj.to_i }.should.equal?(b)
   end
 
   it "uses max.<=>(current) to determine order" do
@@ -48,7 +48,7 @@ describe "Enumerable#max_by" do
 
     context "without a block" do
       it "returns an enumerator" do
-        @enum.max_by(2).should be_an_instance_of(Enumerator)
+        @enum.max_by(2).should.instance_of?(Enumerator)
       end
     end
 
@@ -67,7 +67,7 @@ describe "Enumerable#max_by" do
 
       context "when n is negative" do
         it "raises an ArgumentError" do
-          -> { @enum.max_by(-1) { |i| i.to_s } }.should raise_error(ArgumentError)
+          -> { @enum.max_by(-1) { |i| i.to_s } }.should.raise(ArgumentError)
         end
       end
     end
diff --git a/spec/ruby/core/enumerable/max_spec.rb b/spec/ruby/core/enumerable/max_spec.rb
index 0c11ca0969..d92700258b 100644
--- a/spec/ruby/core/enumerable/max_spec.rb
+++ b/spec/ruby/core/enumerable/max_spec.rb
@@ -38,16 +38,16 @@ describe "Enumerable#max" do
   it "raises a NoMethodError for elements without #<=>" do
     -> do
       EnumerableSpecs::EachDefiner.new(BasicObject.new, BasicObject.new).max
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "raises an ArgumentError for incomparable elements" do
     -> do
       EnumerableSpecs::EachDefiner.new(11,"22").max
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       EnumerableSpecs::EachDefiner.new(11,12,22,33).max{|a, b| nil}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   context "when passed a block" do
@@ -106,7 +106,7 @@ describe "Enumerable#max" do
 
     context "that is negative" do
       it "raises an ArgumentError" do
-        -> { @e_ints.max(-1) }.should raise_error(ArgumentError)
+        -> { @e_ints.max(-1) }.should.raise(ArgumentError)
       end
     end
   end
diff --git a/spec/ruby/core/enumerable/min_by_spec.rb b/spec/ruby/core/enumerable/min_by_spec.rb
index 3ff87e49d8..4f949e2130 100644
--- a/spec/ruby/core/enumerable/min_by_spec.rb
+++ b/spec/ruby/core/enumerable/min_by_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/enumerable_enumeratorized'
 
 describe "Enumerable#min_by" do
   it "returns an enumerator if no block" do
-    EnumerableSpecs::Numerous.new(42).min_by.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new(42).min_by.should.instance_of?(Enumerator)
   end
 
   it "returns nil if #each yields no objects" do
@@ -18,7 +18,7 @@ describe "Enumerable#min_by" do
 
   it "returns the object that appears first in #each in case of a tie" do
     a, b, c = '2', '1', '1'
-    EnumerableSpecs::Numerous.new(a, b, c).min_by {|obj| obj.to_i }.should equal(b)
+    EnumerableSpecs::Numerous.new(a, b, c).min_by {|obj| obj.to_i }.should.equal?(b)
   end
 
   it "uses min.<=>(current) to determine order" do
@@ -48,7 +48,7 @@ describe "Enumerable#min_by" do
 
     context "without a block" do
       it "returns an enumerator" do
-        @enum.min_by(2).should be_an_instance_of(Enumerator)
+        @enum.min_by(2).should.instance_of?(Enumerator)
       end
     end
 
@@ -67,7 +67,7 @@ describe "Enumerable#min_by" do
 
       context "when n is negative" do
         it "raises an ArgumentError" do
-          -> { @enum.min_by(-1) { |i| i.to_s } }.should raise_error(ArgumentError)
+          -> { @enum.min_by(-1) { |i| i.to_s } }.should.raise(ArgumentError)
         end
       end
     end
diff --git a/spec/ruby/core/enumerable/min_spec.rb b/spec/ruby/core/enumerable/min_spec.rb
index 4b6ae248fa..f05d59c2c9 100644
--- a/spec/ruby/core/enumerable/min_spec.rb
+++ b/spec/ruby/core/enumerable/min_spec.rb
@@ -32,22 +32,22 @@ describe "Enumerable#min" do
   end
 
   it "returns nil for an empty Enumerable" do
-    EnumerableSpecs::EachDefiner.new.min.should be_nil
+    EnumerableSpecs::EachDefiner.new.min.should == nil
   end
 
   it "raises a NoMethodError for elements without #<=>" do
     -> do
       EnumerableSpecs::EachDefiner.new(BasicObject.new, BasicObject.new).min
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "raises an ArgumentError for incomparable elements" do
     -> do
       EnumerableSpecs::EachDefiner.new(11,"22").min
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
     -> do
       EnumerableSpecs::EachDefiner.new(11,12,22,33).min{|a, b| nil}
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "returns the minimum when using a block rule" do
@@ -110,7 +110,7 @@ describe "Enumerable#min" do
 
     context "that is negative" do
       it "raises an ArgumentError" do
-        -> { @e_ints.min(-1) }.should raise_error(ArgumentError)
+        -> { @e_ints.min(-1) }.should.raise(ArgumentError)
       end
     end
   end
diff --git a/spec/ruby/core/enumerable/minmax_by_spec.rb b/spec/ruby/core/enumerable/minmax_by_spec.rb
index a6a9249270..30c88cfcfb 100644
--- a/spec/ruby/core/enumerable/minmax_by_spec.rb
+++ b/spec/ruby/core/enumerable/minmax_by_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/enumerable_enumeratorized'
 
 describe "Enumerable#minmax_by" do
   it "returns an enumerator if no block" do
-    EnumerableSpecs::Numerous.new(42).minmax_by.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new(42).minmax_by.should.instance_of?(Enumerator)
   end
 
   it "returns nil if #each yields no objects" do
@@ -19,8 +19,8 @@ describe "Enumerable#minmax_by" do
   it "returns the object that appears first in #each in case of a tie" do
     a, b, c, d = '1', '1', '2', '2'
     mm = EnumerableSpecs::Numerous.new(a, b, c, d).minmax_by {|obj| obj.to_i }
-    mm[0].should equal(a)
-    mm[1].should equal(c)
+    mm[0].should.equal?(a)
+    mm[1].should.equal?(c)
   end
 
   it "uses min/max.<=>(current) to determine order" do
diff --git a/spec/ruby/core/enumerable/minmax_spec.rb b/spec/ruby/core/enumerable/minmax_spec.rb
index 29f1ecf82c..f5f17ef079 100644
--- a/spec/ruby/core/enumerable/minmax_spec.rb
+++ b/spec/ruby/core/enumerable/minmax_spec.rb
@@ -1,41 +1,17 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../shared/enumerable/minmax'
 
 describe "Enumerable#minmax" do
   before :each do
     @enum = EnumerableSpecs::Numerous.new(6, 4, 5, 10, 8)
-
+    @empty_enum = EnumerableSpecs::Empty.new
+    @incomparable_enum = EnumerableSpecs::Numerous.new(BasicObject.new, BasicObject.new)
+    @incompatible_enum = EnumerableSpecs::Numerous.new(11,"22")
     @strs = EnumerableSpecs::Numerous.new("333", "2", "60", "55555", "1010", "111")
   end
 
-  it "min should return the minimum element" do
-    @enum.minmax.should == [4, 10]
-    @strs.minmax.should == ["1010", "60" ]
-  end
-
-  it "returns [nil, nil] for an empty Enumerable" do
-    EnumerableSpecs::Empty.new.minmax.should == [nil, nil]
-  end
-
-  it "raises an ArgumentError when elements are incomparable" do
-    -> do
-      EnumerableSpecs::Numerous.new(11,"22").minmax
-    end.should raise_error(ArgumentError)
-    -> do
-      EnumerableSpecs::Numerous.new(11,12,22,33).minmax{|a, b| nil}
-    end.should raise_error(ArgumentError)
-  end
-
-  it "raises a NoMethodError for elements without #<=>" do
-    -> do
-      EnumerableSpecs::Numerous.new(BasicObject.new, BasicObject.new).minmax
-    end.should raise_error(NoMethodError)
-  end
-
-  it "returns the minimum when using a block rule" do
-    @enum.minmax {|a,b| b <=> a }.should == [10, 4]
-    @strs.minmax {|a,b| a.length <=> b.length }.should == ["2", "55555"]
-  end
+  it_behaves_like :enumerable_minmax, :minmax
 
   it "gathers whole arrays as elements when each yields multiple" do
     multi = EnumerableSpecs::YieldsMulti.new
diff --git a/spec/ruby/core/enumerable/none_spec.rb b/spec/ruby/core/enumerable/none_spec.rb
index 7c17e58a13..d9ee0b441e 100644
--- a/spec/ruby/core/enumerable/none_spec.rb
+++ b/spec/ruby/core/enumerable/none_spec.rb
@@ -10,49 +10,40 @@ describe "Enumerable#none?" do
   end
 
   it "always returns true on empty enumeration" do
-    @empty.none?.should == true
+    @empty.should.none?
     @empty.none? { true }.should == true
   end
 
   it "raises an ArgumentError when more than 1 argument is provided" do
-    -> { @enum.none?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { [].none?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { {}.none?(1, 2, 3) }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is ""..."2.5" do
-    it "raises an ArgumentError when any arguments provided" do
-      -> { @enum.none?(Proc.new {}) }.should raise_error(ArgumentError)
-      -> { @enum.none?(nil) }.should raise_error(ArgumentError)
-      -> { @empty.none?(1) }.should raise_error(ArgumentError)
-      -> { @enum.none?(1) {} }.should raise_error(ArgumentError)
-    end
+    -> { @enum.none?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { [].none?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { {}.none?(1, 2, 3) }.should.raise(ArgumentError)
   end
 
   it "does not hide exceptions out of #each" do
     -> {
       EnumerableSpecs::ThrowingEach.new.none?
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
 
     -> {
       EnumerableSpecs::ThrowingEach.new.none? { false }
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
   end
 
   describe "with no block" do
     it "returns true if none of the elements in self are true" do
       e = EnumerableSpecs::Numerous.new(false, nil, false)
-      e.none?.should be_true
+      e.none?.should == true
     end
 
     it "returns false if at least one of the elements in self are true" do
       e = EnumerableSpecs::Numerous.new(false, nil, true, false)
-      e.none?.should be_false
+      e.none?.should == false
     end
 
     it "gathers whole arrays as elements when each yields multiple" do
       multi = EnumerableSpecs::YieldsMultiWithFalse.new
-      multi.none?.should be_false
+      multi.none?.should == false
     end
   end
 
@@ -74,17 +65,17 @@ describe "Enumerable#none?" do
     end
 
     it "returns true if the block never returns true" do
-      @e.none? {|e| false }.should be_true
+      @e.none? {|e| false }.should == true
     end
 
     it "returns false if the block ever returns true" do
-      @e.none? {|e| e == 3 ? true : false }.should be_false
+      @e.none? {|e| e == 3 ? true : false }.should == false
     end
 
     it "does not hide exceptions out of the block" do
       -> {
         @enum.none? { raise "from block" }
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
 
     it "gathers initial args as elements when each yields multiple" do
@@ -102,66 +93,61 @@ describe "Enumerable#none?" do
     end
   end
 
-  ruby_version_is "2.5" do
-    describe 'when given a pattern argument' do
-      it "calls `===` on the pattern the return value " do
-        pattern = EnumerableSpecs::Pattern.new { |x| x == 3 }
-        @enum1.none?(pattern).should == true
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-      end
-
-      # may raise an exception in future versions
-      ruby_version_is ""..."2.6" do
-        it "ignores block" do
-          @enum2.none?(Integer) { raise }.should == true
-          [1, 2, nil].none?(TrueClass) { raise }.should == true
-          {a: 1}.none?(Hash) { raise }.should == true
-        end
-      end
-
-      it "always returns true on empty enumeration" do
-        @empty.none?(Integer).should == true
-        [].none?(Integer).should == true
-        {}.none?(NilClass).should == true
-      end
-
-      it "does not hide exceptions out of #each" do
-        -> {
-          EnumerableSpecs::ThrowingEach.new.none?(Integer)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "returns true if the pattern never returns a truthy value" do
-        @enum2.none?(Integer).should == true
-        pattern = EnumerableSpecs::Pattern.new { |x| nil }
-        @enum.none?(pattern).should == true
-
-        [1, 42, 3].none?(pattern).should == true
-        {a: 1, b: 2}.none?(pattern).should == true
-      end
-
-      it "returns false if the pattern ever returns other than false or nil" do
-        pattern = EnumerableSpecs::Pattern.new { |x| x < 0 }
-        @enum1.none?(pattern).should == false
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-
-        [1, 2, 3, -1].none?(pattern).should == false
-        {a: 1}.none?(Array).should == false
-      end
-
-      it "does not hide exceptions out of pattern#===" do
-        pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
-        -> {
-          @enum.none?(pattern)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "calls the pattern with gathered array when yielded with multiple arguments" do
-        multi = EnumerableSpecs::YieldsMulti.new
-        pattern = EnumerableSpecs::Pattern.new { false }
-        multi.none?(pattern).should == true
-        pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
-      end
+  describe 'when given a pattern argument' do
+    it "calls `===` on the pattern the return value" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x == 3 }
+      @enum1.none?(pattern).should == true
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+    end
+
+    it "always returns true on empty enumeration" do
+      @empty.none?(Integer).should == true
+      [].none?(Integer).should == true
+      {}.none?(NilClass).should == true
+    end
+
+    it "does not hide exceptions out of #each" do
+      -> {
+        EnumerableSpecs::ThrowingEach.new.none?(Integer)
+      }.should.raise(RuntimeError)
+    end
+
+    it "returns true if the pattern never returns a truthy value" do
+      @enum2.none?(Integer).should == true
+      pattern = EnumerableSpecs::Pattern.new { |x| nil }
+      @enum.none?(pattern).should == true
+
+      [1, 42, 3].none?(pattern).should == true
+      {a: 1, b: 2}.none?(pattern).should == true
+    end
+
+    it "returns false if the pattern ever returns other than false or nil" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x < 0 }
+      @enum1.none?(pattern).should == false
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+
+      [1, 2, 3, -1].none?(pattern).should == false
+      {a: 1}.none?(Array).should == false
+    end
+
+    it "does not hide exceptions out of pattern#===" do
+      pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
+      -> {
+        @enum.none?(pattern)
+      }.should.raise(RuntimeError)
+    end
+
+    it "calls the pattern with gathered array when yielded with multiple arguments" do
+      multi = EnumerableSpecs::YieldsMulti.new
+      pattern = EnumerableSpecs::Pattern.new { false }
+      multi.none?(pattern).should == true
+      pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
+    end
+
+    it "ignores the block if there is an argument" do
+      -> {
+        EnumerableSpecs::Numerous.new(1, 2, 3, 4, 5).none?(String) { true }.should == true
+      }.should complain(/given block not used/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/one_spec.rb b/spec/ruby/core/enumerable/one_spec.rb
index 2ae8b3efa4..cf966d4a9b 100644
--- a/spec/ruby/core/enumerable/one_spec.rb
+++ b/spec/ruby/core/enumerable/one_spec.rb
@@ -10,71 +10,62 @@ describe "Enumerable#one?" do
   end
 
   it "always returns false on empty enumeration" do
-    @empty.one?.should == false
+    @empty.should_not.one?
     @empty.one? { true }.should == false
   end
 
   it "raises an ArgumentError when more than 1 argument is provided" do
-    -> { @enum.one?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { [].one?(1, 2, 3) }.should raise_error(ArgumentError)
-    -> { {}.one?(1, 2, 3) }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is ""..."2.5" do
-    it "raises an ArgumentError when any arguments provided" do
-      -> { @enum.one?(Proc.new {}) }.should raise_error(ArgumentError)
-      -> { @enum.one?(nil) }.should raise_error(ArgumentError)
-      -> { @empty.one?(1) }.should raise_error(ArgumentError)
-      -> { @enum.one?(1) {} }.should raise_error(ArgumentError)
-    end
+    -> { @enum.one?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { [].one?(1, 2, 3) }.should.raise(ArgumentError)
+    -> { {}.one?(1, 2, 3) }.should.raise(ArgumentError)
   end
 
   it "does not hide exceptions out of #each" do
     -> {
       EnumerableSpecs::ThrowingEach.new.one?
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
 
     -> {
       EnumerableSpecs::ThrowingEach.new.one? { false }
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
   end
 
   describe "with no block" do
     it "returns true if only one element evaluates to true" do
-      [false, nil, true].one?.should be_true
+      [false, nil, true].one?.should == true
     end
 
     it "returns false if two elements evaluate to true" do
-      [false, :value, nil, true].one?.should be_false
+      [false, :value, nil, true].one?.should == false
     end
 
     it "returns false if all elements evaluate to false" do
-      [false, nil, false].one?.should be_false
+      [false, nil, false].one?.should == false
     end
 
     it "gathers whole arrays as elements when each yields multiple" do
       multi = EnumerableSpecs::YieldsMultiWithSingleTrue.new
-      multi.one?.should be_false
+      multi.one?.should == false
     end
   end
 
   describe "with a block" do
     it "returns true if block returns true once" do
-      [:a, :b, :c].one? { |s| s == :a }.should be_true
+      [:a, :b, :c].one? { |s| s == :a }.should == true
     end
 
     it "returns false if the block returns true more than once" do
-      [:a, :b, :c].one? { |s| s == :a || s == :b }.should be_false
+      [:a, :b, :c].one? { |s| s == :a || s == :b }.should == false
     end
 
     it "returns false if the block only returns false" do
-      [:a, :b, :c].one? { |s| s == :d }.should be_false
+      [:a, :b, :c].one? { |s| s == :d }.should == false
     end
 
     it "does not hide exceptions out of the block" do
       -> {
         @enum.one? { raise "from block" }
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
 
     it "gathers initial args as elements when each yields multiple" do
@@ -92,78 +83,72 @@ describe "Enumerable#one?" do
     end
   end
 
+  describe 'when given a pattern argument' do
+    it "calls `===` on the pattern the return value" do
+      pattern = EnumerableSpecs::Pattern.new { |x| x == 1 }
+      @enum1.one?(pattern).should == true
+      pattern.yielded.should == [[0], [1], [2], [-1]]
+    end
+
+    it "always returns false on empty enumeration" do
+      @empty.one?(Integer).should == false
+      [].one?(Integer).should == false
+      {}.one?(NilClass).should == false
+    end
+
+    it "does not hide exceptions out of #each" do
+      -> {
+        EnumerableSpecs::ThrowingEach.new.one?(Integer)
+      }.should.raise(RuntimeError)
+    end
+
+    it "returns true if the pattern returns a truthy value only once" do
+      @enum2.one?(NilClass).should == true
+      pattern = EnumerableSpecs::Pattern.new { |x| x == 2 }
+      @enum1.one?(pattern).should == true
+
+      [1, 2, 42, 3].one?(pattern).should == true
+
+      pattern = EnumerableSpecs::Pattern.new { |x| x == [:b, 2] }
+      {a: 1, b: 2}.one?(pattern).should == true
+    end
+
+    it "returns false if the pattern returns a truthy value more than once" do
+      pattern = EnumerableSpecs::Pattern.new { |x| !x }
+      @enum2.one?(pattern).should == false
+      pattern.yielded.should == [[nil], [false]]
+
+      [1, 2, 3].one?(Integer).should == false
+      {a: 1, b: 2}.one?(Array).should == false
+    end
+
+    it "returns false if the pattern never returns a truthy value" do
+      pattern = EnumerableSpecs::Pattern.new { |x| nil }
+      @enum1.one?(pattern).should == false
+      pattern.yielded.should == [[0], [1], [2], [-1]]
 
-  ruby_version_is "2.5" do
-    describe 'when given a pattern argument' do
-      it "calls `===` on the pattern the return value " do
-        pattern = EnumerableSpecs::Pattern.new { |x| x == 1 }
-        @enum1.one?(pattern).should == true
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-      end
-
-      # may raise an exception in future versions
-      ruby_version_is ""..."2.6" do
-        it "ignores block" do
-          @enum2.one?(NilClass) { raise }.should == true
-          [1, 2, nil].one?(NilClass) { raise }.should == true
-          {a: 1}.one?(Array) { raise }.should == true
-        end
-      end
-
-      it "always returns false on empty enumeration" do
-        @empty.one?(Integer).should == false
-        [].one?(Integer).should == false
-        {}.one?(NilClass).should == false
-      end
-
-      it "does not hide exceptions out of #each" do
-        -> {
-          EnumerableSpecs::ThrowingEach.new.one?(Integer)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "returns true if the pattern returns a truthy value only once" do
-        @enum2.one?(NilClass).should == true
-        pattern = EnumerableSpecs::Pattern.new { |x| x == 2 }
-        @enum1.one?(pattern).should == true
-
-        [1, 2, 42, 3].one?(pattern).should == true
-
-        pattern = EnumerableSpecs::Pattern.new { |x| x == [:b, 2] }
-        {a: 1, b: 2}.one?(pattern).should == true
-      end
-
-      it "returns false if the pattern returns a truthy value more than once" do
-        pattern = EnumerableSpecs::Pattern.new { |x| !x }
-        @enum2.one?(pattern).should == false
-        pattern.yielded.should == [[nil], [false]]
-
-        [1, 2, 3].one?(Integer).should == false
-        {a: 1, b: 2}.one?(Array).should == false
-      end
-
-      it "returns false if the pattern never returns a truthy value" do
-        pattern = EnumerableSpecs::Pattern.new { |x| nil }
-        @enum1.one?(pattern).should == false
-        pattern.yielded.should == [[0], [1], [2], [-1]]
-
-        [1, 2, 3].one?(pattern).should == false
-        {a: 1}.one?(pattern).should == false
-      end
-
-      it "does not hide exceptions out of pattern#===" do
-        pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
-        -> {
-          @enum.one?(pattern)
-        }.should raise_error(RuntimeError)
-      end
-
-      it "calls the pattern with gathered array when yielded with multiple arguments" do
-        multi = EnumerableSpecs::YieldsMulti.new
-        pattern = EnumerableSpecs::Pattern.new { false }
-        multi.one?(pattern).should == false
-        pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
-      end
+      [1, 2, 3].one?(pattern).should == false
+      {a: 1}.one?(pattern).should == false
+    end
+
+    it "does not hide exceptions out of pattern#===" do
+      pattern = EnumerableSpecs::Pattern.new { raise "from pattern" }
+      -> {
+        @enum.one?(pattern)
+      }.should.raise(RuntimeError)
+    end
+
+    it "calls the pattern with gathered array when yielded with multiple arguments" do
+      multi = EnumerableSpecs::YieldsMulti.new
+      pattern = EnumerableSpecs::Pattern.new { false }
+      multi.one?(pattern).should == false
+      pattern.yielded.should == [[[1, 2]], [[3, 4, 5]], [[6, 7, 8, 9]]]
+    end
+
+    it "ignores the block if there is an argument" do
+      -> {
+        EnumerableSpecs::Numerous.new(1, 2, 3, 4, "5").one?(String) { false }.should == true
+      }.should complain(/given block not used/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/partition_spec.rb b/spec/ruby/core/enumerable/partition_spec.rb
index d3d220b4b4..8272ee189e 100644
--- a/spec/ruby/core/enumerable/partition_spec.rb
+++ b/spec/ruby/core/enumerable/partition_spec.rb
@@ -8,7 +8,7 @@ describe "Enumerable#partition" do
   end
 
   it "returns an Enumerator if called without a block" do
-    EnumerableSpecs::Numerous.new.partition.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new.partition.should.instance_of?(Enumerator)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/reject_spec.rb b/spec/ruby/core/enumerable/reject_spec.rb
index 0d86b49ea2..31e89f5b0e 100644
--- a/spec/ruby/core/enumerable/reject_spec.rb
+++ b/spec/ruby/core/enumerable/reject_spec.rb
@@ -13,7 +13,7 @@ describe "Enumerable#reject" do
   end
 
   it "returns an Enumerator if called without a block" do
-    EnumerableSpecs::Numerous.new.reject.should be_an_instance_of(Enumerator)
+    EnumerableSpecs::Numerous.new.reject.should.instance_of?(Enumerator)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/reverse_each_spec.rb b/spec/ruby/core/enumerable/reverse_each_spec.rb
index 2b1c233488..4753956724 100644
--- a/spec/ruby/core/enumerable/reverse_each_spec.rb
+++ b/spec/ruby/core/enumerable/reverse_each_spec.rb
@@ -11,7 +11,7 @@ describe "Enumerable#reverse_each" do
 
   it "returns an Enumerator if no block given" do
     enum = EnumerableSpecs::Numerous.new.reverse_each
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == [4, 1, 6, 3, 5, 2]
   end
 
diff --git a/spec/ruby/core/enumerable/select_spec.rb b/spec/ruby/core/enumerable/select_spec.rb
index 11168eb42e..7fc61926f9 100644
--- a/spec/ruby/core/enumerable/select_spec.rb
+++ b/spec/ruby/core/enumerable/select_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/find_all'
 
 describe "Enumerable#select" do
-  it_behaves_like :enumerable_find_all , :select
+  it_behaves_like :enumerable_find_all, :select
 end
diff --git a/spec/ruby/core/enumerable/shared/collect.rb b/spec/ruby/core/enumerable/shared/collect.rb
index 16bf3f0d35..4696d32454 100644
--- a/spec/ruby/core/enumerable/shared/collect.rb
+++ b/spec/ruby/core/enumerable/shared/collect.rb
@@ -22,11 +22,86 @@ describe :enumerable_collect, shared: true do
     multi.send(@method) {|e| e}.should == [1,3,6]
   end
 
+  it "only yields increasing values for a Range" do
+    (1..0).send(@method) { |x| x }.should == []
+    (1..1).send(@method) { |x| x }.should == [1]
+    (1..2).send(@method) { |x| x }.should == [1, 2]
+  end
+
   it "returns an enumerator when no block given" do
     enum = EnumerableSpecs::Numerous.new.send(@method)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.each { |i| -i }.should == [-2, -5, -3, -6, -1, -4]
   end
 
+  it "reports the same arity as the given block" do
+    entries = [0, 1, 3, 4, 5, 6]
+    numerous = EnumerableSpecs::Numerous.new(*entries)
+
+    def numerous.each(&block)
+      ScratchPad << block.arity
+      super
+    end
+
+    numerous.send(@method) { |a, b| a % 2 }.should == [0, 1, 1, 0, 1, 0]
+    ScratchPad.recorded.should == [2]
+    ScratchPad.clear
+    ScratchPad.record []
+    numerous.send(@method) { |i| i }.should == entries
+    ScratchPad.recorded.should == [1]
+  end
+
+  it "yields an Array of 2 elements for a Hash when block arity is 1" do
+    c = Class.new do
+      def register(a)
+        ScratchPad << a
+      end
+    end
+    m = c.new.method(:register)
+
+    ScratchPad.record []
+    { 1 => 'a', 2 => 'b' }.map(&m)
+    ScratchPad.recorded.should == [[1, 'a'], [2, 'b']]
+  end
+
+  it "yields 2 arguments for a Hash when block arity is 2" do
+    c = Class.new do
+      def register(a, b)
+        ScratchPad << [a, b]
+      end
+    end
+    m = c.new.method(:register)
+
+    ScratchPad.record []
+    { 1 => 'a', 2 => 'b' }.map(&m)
+    ScratchPad.recorded.should == [[1, 'a'], [2, 'b']]
+  end
+
+  it "raises an error for a Hash when an arity enforcing block of arity >2 is passed in" do
+    c = Class.new do
+      def register(a, b, c)
+      end
+    end
+    m = c.new.method(:register)
+
+    -> do
+      { 1 => 'a', 2 => 'b' }.map(&m)
+    end.should.raise(ArgumentError)
+  end
+
+  it "calls the each method on sub-classes" do
+    c = Class.new(Hash) do
+      def each
+        ScratchPad << 'in each'
+        super
+      end
+    end
+    h = c.new
+    h[1] = 'a'
+    ScratchPad.record []
+    h.send(@method) { |k,v| v }
+    ScratchPad.recorded.should == ['in each']
+  end
+
   it_should_behave_like :enumerable_enumeratorized_with_origin_size
 end
diff --git a/spec/ruby/core/enumerable/shared/collect_concat.rb b/spec/ruby/core/enumerable/shared/collect_concat.rb
index ddd431baeb..1694e3fdce 100644
--- a/spec/ruby/core/enumerable/shared/collect_concat.rb
+++ b/spec/ruby/core/enumerable/shared/collect_concat.rb
@@ -41,12 +41,12 @@ describe :enumerable_collect_concat, shared: true do
     obj = mock("to_ary defined")
     obj.should_receive(:to_ary).and_return("array")
 
-    -> { [1, obj, 3].send(@method) { |i| i } }.should raise_error(TypeError)
+    -> { [1, obj, 3].send(@method) { |i| i } }.should.raise(TypeError)
   end
 
   it "returns an enumerator when no block given" do
     enum = EnumerableSpecs::Numerous.new(1, 2).send(@method)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.each{ |i| [i] * i }.should == [1, 2, 2]
   end
 
diff --git a/spec/ruby/core/enumerable/shared/entries.rb b/spec/ruby/core/enumerable/shared/entries.rb
index f52844cb45..e32eb23d2a 100644
--- a/spec/ruby/core/enumerable/shared/entries.rb
+++ b/spec/ruby/core/enumerable/shared/entries.rb
@@ -13,12 +13,4 @@ describe :enumerable_entries, shared: true do
     count.send(@method, :hello, "world").should == [1, 2, 3]
     count.arguments_passed.should == [:hello, "world"]
   end
-
-  it "returns a tainted array if self is tainted" do
-    EnumerableSpecs::Empty.new.taint.send(@method).tainted?.should be_true
-  end
-
-  it "returns an untrusted array if self is untrusted" do
-    EnumerableSpecs::Empty.new.untrust.send(@method).untrusted?.should be_true
-  end
 end
diff --git a/spec/ruby/core/enumerable/shared/find.rb b/spec/ruby/core/enumerable/shared/find.rb
index 61d63ba3d5..cdff640415 100644
--- a/spec/ruby/core/enumerable/shared/find.rb
+++ b/spec/ruby/core/enumerable/shared/find.rb
@@ -59,7 +59,7 @@ describe :enumerable_find, shared: true do
   end
 
   it "returns an enumerator when no block given" do
-    @numerous.send(@method).should be_an_instance_of(Enumerator)
+    @numerous.send(@method).should.instance_of?(Enumerator)
   end
 
   it "passes the ifnone proc to the enumerator" do
diff --git a/spec/ruby/core/enumerable/shared/find_all.rb b/spec/ruby/core/enumerable/shared/find_all.rb
index 1bbe71f372..27f01de6e0 100644
--- a/spec/ruby/core/enumerable/shared/find_all.rb
+++ b/spec/ruby/core/enumerable/shared/find_all.rb
@@ -14,7 +14,7 @@ describe :enumerable_find_all, shared: true do
   end
 
   it "returns an enumerator when no block given" do
-    @numerous.send(@method).should be_an_instance_of(Enumerator)
+    @numerous.send(@method).should.instance_of?(Enumerator)
   end
 
   it "passes through the values yielded by #each_with_index" do
diff --git a/spec/ruby/core/enumerable/shared/include.rb b/spec/ruby/core/enumerable/shared/include.rb
index 569f350fd5..ea250f032b 100644
--- a/spec/ruby/core/enumerable/shared/include.rb
+++ b/spec/ruby/core/enumerable/shared/include.rb
@@ -28,7 +28,7 @@ describe :enumerable_include, shared: true do
 
   it "gathers whole arrays as elements when each yields multiple" do
     multi = EnumerableSpecs::YieldsMulti.new
-    multi.send(@method, [1,2]).should be_true
+    multi.send(@method, [1,2]).should == true
   end
 
 end
diff --git a/spec/ruby/core/enumerable/shared/inject.rb b/spec/ruby/core/enumerable/shared/inject.rb
index 12e0665dda..7da4f0ca99 100644
--- a/spec/ruby/core/enumerable/shared/inject.rb
+++ b/spec/ruby/core/enumerable/shared/inject.rb
@@ -1,3 +1,5 @@
+require_relative '../../array/shared/iterable_and_tolerating_size_increasing'
+
 describe :enumerable_inject, shared: true do
   it "with argument takes a block with an accumulator (with argument as initial value) and the current element. Value of block becomes new accumulator" do
     a = []
@@ -14,14 +16,65 @@ describe :enumerable_inject, shared: true do
 
   it "can take two argument" do
     EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, :-).should == 4
+    EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, "-").should == 4
+
+    [1, 2, 3].send(@method, 10, :-).should == 4
+    [1, 2, 3].send(@method, 10, "-").should == 4
+  end
+
+  it "converts non-Symbol method name argument to String with #to_str if two arguments" do
+    name = Object.new
+    def name.to_str; "-"; end
+
+    EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, name).should == 4
+    [1, 2, 3].send(@method, 10, name).should == 4
+  end
+
+  it "raises TypeError when the second argument is not Symbol or String and it cannot be converted to String if two arguments" do
+    -> { EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, Object.new) }.should.raise(TypeError, /is not a symbol nor a string/)
+    -> { [1, 2, 3].send(@method, 10, Object.new) }.should.raise(TypeError, /is not a symbol nor a string/)
   end
 
   it "ignores the block if two arguments" do
-    EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, :-){ raise "we never get here"}.should == 4
+    -> {
+      EnumerableSpecs::Numerous.new(1, 2, 3).send(@method, 10, :-) { raise "we never get here"}.should == 4
+    }.should complain(/#{__FILE__}:#{__LINE__-1}: warning: given block not used/, verbose: true)
+
+    -> {
+      [1, 2, 3].send(@method, 10, :-) { raise "we never get here"}.should == 4
+    }.should complain(/#{__FILE__}:#{__LINE__-1}: warning: given block not used/, verbose: true)
+  end
+
+  it "does not warn when given a Symbol with $VERBOSE true" do
+    -> {
+      [1, 2].send(@method, 0, :+)
+      [1, 2].send(@method, :+)
+      EnumerableSpecs::Numerous.new(1, 2).send(@method, 0, :+)
+      EnumerableSpecs::Numerous.new(1, 2).send(@method, :+)
+    }.should_not complain(verbose: true)
   end
 
   it "can take a symbol argument" do
     EnumerableSpecs::Numerous.new(10, 1, 2, 3).send(@method, :-).should == 4
+    [10, 1, 2, 3].send(@method, :-).should == 4
+  end
+
+  it "can take a String argument" do
+    EnumerableSpecs::Numerous.new(10, 1, 2, 3).send(@method, "-").should == 4
+    [10, 1, 2, 3].send(@method, "-").should == 4
+  end
+
+  it "converts non-Symbol method name argument to String with #to_str" do
+    name = Object.new
+    def name.to_str; "-"; end
+
+    EnumerableSpecs::Numerous.new(10, 1, 2, 3).send(@method, name).should == 4
+    [10, 1, 2, 3].send(@method, name).should == 4
+  end
+
+  it "raises TypeError when passed not Symbol or String method name argument and it cannot be converted to String" do
+    -> { EnumerableSpecs::Numerous.new(10, 1, 2, 3).send(@method, Object.new) }.should.raise(TypeError, /is not a symbol nor a string/)
+    -> { [10, 1, 2, 3].send(@method, Object.new) }.should.raise(TypeError, /is not a symbol nor a string/)
   end
 
   it "without argument takes a block with an accumulator (with first element as initial value) and the current element. Value of block becomes new accumulator" do
@@ -30,10 +83,10 @@ describe :enumerable_inject, shared: true do
     a.should == [[2, 5], [5, 3], [3, 6], [6, 1], [1, 4]]
   end
 
-   it "gathers whole arrays as elements when each yields multiple" do
-     multi = EnumerableSpecs::YieldsMulti.new
-     multi.send(@method, []) {|acc, e| acc << e }.should == [[1, 2], [3, 4, 5], [6, 7, 8, 9]]
-   end
+  it "gathers whole arrays as elements when each yields multiple" do
+    multi = EnumerableSpecs::YieldsMulti.new
+    multi.send(@method, []) {|acc, e| acc << e }.should == [[1, 2], [3, 4, 5], [6, 7, 8, 9]]
+  end
 
   it "with inject arguments(legacy rubycon)" do
     # with inject argument
@@ -50,7 +103,7 @@ describe :enumerable_inject, shared: true do
 
   it "without inject arguments(legacy rubycon)" do
     # no inject argument
-    EnumerableSpecs::EachDefiner.new(2).send(@method) {|acc,x| 999 } .should == 2
+    EnumerableSpecs::EachDefiner.new(2).send(@method) {|acc,x| 999 }.should == 2
     EnumerableSpecs::EachDefiner.new(2).send(@method) {|acc,x| acc }.should == 2
     EnumerableSpecs::EachDefiner.new(2).send(@method) {|acc,x| x }.should == 2
 
@@ -60,10 +113,30 @@ describe :enumerable_inject, shared: true do
     EnumerableSpecs::EachDefiner.new('a','b','c').send(@method) {|result, i| i+result}.should == "cba"
     EnumerableSpecs::EachDefiner.new(3, 4, 5).send(@method) {|result, i| result*i}.should == 60
     EnumerableSpecs::EachDefiner.new([1], 2, 'a','b').send(@method){|r,i| r<<i}.should == [1, 2, 'a', 'b']
-
   end
 
   it "returns nil when fails(legacy rubycon)" do
     EnumerableSpecs::EachDefiner.new().send(@method) {|acc,x| 999 }.should == nil
   end
+
+  it "tolerates increasing a collection size during iterating Array" do
+    array = [:a, :b, :c]
+    ScratchPad.record []
+    i = 0
+
+    array.send(@method, nil) do |_, e|
+      ScratchPad << e
+      array << i if i < 100
+      i += 1
+    end
+
+    actual = ScratchPad.recorded
+    expected = [:a, :b, :c] + (0..99).to_a
+    actual.sort_by(&:to_s).should == expected.sort_by(&:to_s)
+  end
+
+  it "raises an ArgumentError when no parameters or block is given" do
+    -> { [1,2].send(@method) }.should.raise(ArgumentError)
+    -> { {one: 1, two: 2}.send(@method) }.should.raise(ArgumentError)
+  end
 end
diff --git a/spec/ruby/core/enumerable/shared/take.rb b/spec/ruby/core/enumerable/shared/take.rb
index ce2ace20fa..a6da06325f 100644
--- a/spec/ruby/core/enumerable/shared/take.rb
+++ b/spec/ruby/core/enumerable/shared/take.rb
@@ -25,7 +25,7 @@ describe :enumerable_take, shared: true do
   end
 
   it "raises an ArgumentError when count is negative" do
-    -> { @enum.send(@method, -1) }.should raise_error(ArgumentError)
+    -> { @enum.send(@method, -1) }.should.raise(ArgumentError)
   end
 
   it "returns the entire array when count > length" do
@@ -40,11 +40,11 @@ describe :enumerable_take, shared: true do
   end
 
   it "raises a TypeError if the passed argument is not numeric" do
-    -> { @enum.send(@method, nil) }.should raise_error(TypeError)
-    -> { @enum.send(@method, "a") }.should raise_error(TypeError)
+    -> { @enum.send(@method, nil) }.should.raise(TypeError)
+    -> { @enum.send(@method, "a") }.should.raise(TypeError)
 
     obj = mock("nonnumeric")
-    -> { @enum.send(@method, obj) }.should raise_error(TypeError)
+    -> { @enum.send(@method, obj) }.should.raise(TypeError)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/shared/value_packing.rb b/spec/ruby/core/enumerable/shared/value_packing.rb
new file mode 100644
index 0000000000..ff77f45cdf
--- /dev/null
+++ b/spec/ruby/core/enumerable/shared/value_packing.rb
@@ -0,0 +1,26 @@
+# This is the behavior of rb_enum_values_pack() in CRuby
+describe :enumerable_value_packing, shared: true do
+  # @take must be set to a Proc that returns the take-result whose #each
+  # yields packed values (e.g. -> e { e.take(1) } or -> e { e.lazy.take(1) }).
+
+  it "yields a single nil for a zero-argument source yield" do
+    e = Enumerator.new { |y| y.yield }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [nil]
+  end
+
+  it "yields the value for a single-argument source yield" do
+    e = Enumerator.new { |y| y.yield :v }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [:v]
+  end
+
+  it "yields a packed Array for a multi-argument source yield" do
+    e = Enumerator.new { |y| y.yield 1, 2 }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [[1, 2]]
+  end
+end
diff --git a/spec/ruby/core/enumerable/slice_after_spec.rb b/spec/ruby/core/enumerable/slice_after_spec.rb
index 0e46688db1..1ef37195e5 100644
--- a/spec/ruby/core/enumerable/slice_after_spec.rb
+++ b/spec/ruby/core/enumerable/slice_after_spec.rb
@@ -11,7 +11,7 @@ describe "Enumerable#slice_after" do
       arg = mock("filter")
       arg.should_receive(:===).and_return(false, true, false, false, false, true, false)
       e = @enum.slice_after(arg)
-      e.should be_an_instance_of(Enumerator)
+      e.should.instance_of?(Enumerator)
       e.to_a.should == [[7, 6], [5, 4, 3, 2], [1]]
     end
 
@@ -34,21 +34,21 @@ describe "Enumerable#slice_after" do
     describe "and no argument" do
       it "calls the block to determine when to yield" do
         e = @enum.slice_after{ |i| i == 6 || i == 2 }
-        e.should be_an_instance_of(Enumerator)
+        e.should.instance_of?(Enumerator)
         e.to_a.should == [[7, 6], [5, 4, 3, 2], [1]]
       end
     end
 
     describe "and an argument" do
       it "raises an ArgumentError" do
-        -> { @enum.slice_after(42) { |i| i == 6 } }.should raise_error(ArgumentError)
+        -> { @enum.slice_after(42) { |i| i == 6 } }.should.raise(ArgumentError)
       end
     end
   end
 
   it "raises an ArgumentError when given an incorrect number of arguments" do
-    -> { @enum.slice_after("one", "two") }.should raise_error(ArgumentError)
-    -> { @enum.slice_after }.should raise_error(ArgumentError)
+    -> { @enum.slice_after("one", "two") }.should.raise(ArgumentError)
+    -> { @enum.slice_after }.should.raise(ArgumentError)
   end
 end
 
diff --git a/spec/ruby/core/enumerable/slice_before_spec.rb b/spec/ruby/core/enumerable/slice_before_spec.rb
index f9b33f7b28..7eb4410a25 100644
--- a/spec/ruby/core/enumerable/slice_before_spec.rb
+++ b/spec/ruby/core/enumerable/slice_before_spec.rb
@@ -12,7 +12,7 @@ describe "Enumerable#slice_before" do
       arg = mock "filter"
       arg.should_receive(:===).and_return(false, true, false, false, false, true, false)
       e = @enum.slice_before(arg)
-      e.should be_an_instance_of(Enumerator)
+      e.should.instance_of?(Enumerator)
       e.to_a.should == [[7], [6, 5, 4, 3], [2, 1]]
     end
 
@@ -35,7 +35,7 @@ describe "Enumerable#slice_before" do
     describe "and no argument" do
       it "calls the block to determine when to yield" do
         e = @enum.slice_before{|i| i == 6 || i == 2}
-        e.should be_an_instance_of(Enumerator)
+        e.should.instance_of?(Enumerator)
         e.to_a.should == [[7], [6, 5, 4, 3], [2, 1]]
       end
     end
@@ -43,13 +43,13 @@ describe "Enumerable#slice_before" do
     it "does not accept arguments" do
       -> {
         @enum.slice_before(1) {}
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
   it "raises an ArgumentError when given an incorrect number of arguments" do
-    -> { @enum.slice_before("one", "two") }.should raise_error(ArgumentError)
-    -> { @enum.slice_before }.should raise_error(ArgumentError)
+    -> { @enum.slice_before("one", "two") }.should.raise(ArgumentError)
+    -> { @enum.slice_before }.should.raise(ArgumentError)
   end
 
   describe "when an iterator method yields more than one value" do
diff --git a/spec/ruby/core/enumerable/slice_when_spec.rb b/spec/ruby/core/enumerable/slice_when_spec.rb
index 6b8ea0923e..fe1ecd31e2 100644
--- a/spec/ruby/core/enumerable/slice_when_spec.rb
+++ b/spec/ruby/core/enumerable/slice_when_spec.rb
@@ -11,7 +11,7 @@ describe "Enumerable#slice_when" do
 
   context "when given a block" do
     it "returns an enumerator" do
-      @result.should be_an_instance_of(Enumerator)
+      @result.should.instance_of?(Enumerator)
     end
 
     it "splits chunks between adjacent elements i and j where the block returns true" do
@@ -39,7 +39,7 @@ describe "Enumerable#slice_when" do
 
   context "when not given a block" do
     it "raises an ArgumentError" do
-      -> { @enum.slice_when }.should raise_error(ArgumentError)
+      -> { @enum.slice_when }.should.raise(ArgumentError)
     end
   end
 
diff --git a/spec/ruby/core/enumerable/sort_by_spec.rb b/spec/ruby/core/enumerable/sort_by_spec.rb
index 8fdd923fb4..62cf38ce3e 100644
--- a/spec/ruby/core/enumerable/sort_by_spec.rb
+++ b/spec/ruby/core/enumerable/sort_by_spec.rb
@@ -18,7 +18,7 @@ describe "Enumerable#sort_by" do
 
   it "returns an Enumerator when a block is not supplied" do
     a = EnumerableSpecs::Numerous.new("a","b")
-    a.sort_by.should be_an_instance_of(Enumerator)
+    a.sort_by.should.instance_of?(Enumerator)
     a.to_a.should == ["a", "b"]
   end
 
diff --git a/spec/ruby/core/enumerable/sort_spec.rb b/spec/ruby/core/enumerable/sort_spec.rb
index cff1a59986..427b1cd8f1 100644
--- a/spec/ruby/core/enumerable/sort_spec.rb
+++ b/spec/ruby/core/enumerable/sort_spec.rb
@@ -16,7 +16,7 @@ describe "Enumerable#sort" do
   it "raises a NoMethodError if elements do not define <=>" do
     -> do
       EnumerableSpecs::Numerous.new(BasicObject.new, BasicObject.new, BasicObject.new).sort
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "sorts enumerables that contain nils" do
@@ -31,16 +31,16 @@ describe "Enumerable#sort" do
   it "compare values returned by block with 0" do
     EnumerableSpecs::Numerous.new.sort { |n, m| -(n+m) * (n <=> m) }.should == [6, 5, 4, 3, 2, 1]
     EnumerableSpecs::Numerous.new.sort { |n, m|
-      EnumerableSpecs::ComparableWithFixnum.new(-(n+m) * (n <=> m))
+      EnumerableSpecs::ComparableWithInteger.new(-(n+m) * (n <=> m))
     }.should == [6, 5, 4, 3, 2, 1]
     -> {
       EnumerableSpecs::Numerous.new.sort { |n, m| (n <=> m).to_s }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if objects can't be compared" do
     a=EnumerableSpecs::Numerous.new(EnumerableSpecs::Uncomparable.new, EnumerableSpecs::Uncomparable.new)
-    -> {a.sort}.should raise_error(ArgumentError)
+    -> {a.sort}.should.raise(ArgumentError)
   end
 
   it "gathers whole arrays as elements when each yields multiple" do
diff --git a/spec/ruby/core/enumerable/sum_spec.rb b/spec/ruby/core/enumerable/sum_spec.rb
index c9d7017b45..2eb74db6ac 100644
--- a/spec/ruby/core/enumerable/sum_spec.rb
+++ b/spec/ruby/core/enumerable/sum_spec.rb
@@ -22,7 +22,29 @@ describe 'Enumerable#sum' do
     @enum.sum.should == 5/3r
   end
 
-  it 'takes a block to transform the elements' do
-    @enum.sum { |element| element * 2 }.should == 10/3r
+  context 'with a block' do
+    it 'transforms the elements' do
+      @enum.sum { |element| element * 2 }.should == 10/3r
+    end
+
+    it 'does not destructure array elements' do
+      class << @enum
+        def each
+          yield [1,2]
+          yield [3]
+        end
+      end
+
+      @enum.sum(&:last).should == 5
+    end
+  end
+
+  # https://bugs.ruby-lang.org/issues/12217
+  # https://github.com/ruby/ruby/blob/master/doc/ChangeLog/ChangeLog-2.4.0#L6208-L6214
+  it "uses Kahan's compensated summation algorithm for precise sum of float numbers" do
+    floats = [2.7800000000000002, 5.0, 2.5, 4.44, 3.89, 3.89, 4.44, 7.78, 5.0, 2.7800000000000002, 5.0, 2.5].to_enum
+    naive_sum = floats.reduce { |sum, e| sum + e }
+    naive_sum.should == 50.00000000000001
+    floats.sum.should == 50.0
   end
 end
diff --git a/spec/ruby/core/enumerable/take_spec.rb b/spec/ruby/core/enumerable/take_spec.rb
index 41a7438330..ca439b750d 100644
--- a/spec/ruby/core/enumerable/take_spec.rb
+++ b/spec/ruby/core/enumerable/take_spec.rb
@@ -1,13 +1,21 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/take'
+require_relative 'shared/value_packing'
 
 describe "Enumerable#take" do
   it "requires an argument" do
-    ->{ EnumerableSpecs::Numerous.new.take}.should raise_error(ArgumentError)
+    ->{ EnumerableSpecs::Numerous.new.take}.should.raise(ArgumentError)
   end
 
   describe "when passed an argument" do
     it_behaves_like :enumerable_take, :take
   end
+
+  describe "value packing of source yields" do
+    before :each do
+      @take = -> e { e.take(1) }
+    end
+    it_behaves_like :enumerable_value_packing, nil
+  end
 end
diff --git a/spec/ruby/core/enumerable/take_while_spec.rb b/spec/ruby/core/enumerable/take_while_spec.rb
index 26db39ac4b..918bfc897d 100644
--- a/spec/ruby/core/enumerable/take_while_spec.rb
+++ b/spec/ruby/core/enumerable/take_while_spec.rb
@@ -8,7 +8,7 @@ describe "Enumerable#take_while" do
   end
 
   it "returns an Enumerator if no block given" do
-    @enum.take_while.should be_an_instance_of(Enumerator)
+    @enum.take_while.should.instance_of?(Enumerator)
   end
 
   it "returns no/all elements for {true/false} block" do
@@ -38,7 +38,7 @@ describe "Enumerable#take_while" do
 
   it "doesn't return self when it could" do
     a = [1,2,3]
-    a.take_while{true}.should_not equal(a)
+    a.take_while{true}.should_not.equal?(a)
   end
 
   it "calls the block with initial args when yielded with multiple arguments" do
diff --git a/spec/ruby/core/enumerable/tally_spec.rb b/spec/ruby/core/enumerable/tally_spec.rb
index 363b3def21..deef741407 100644
--- a/spec/ruby/core/enumerable/tally_spec.rb
+++ b/spec/ruby/core/enumerable/tally_spec.rb
@@ -1,35 +1,91 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.7" do
-  describe "Enumerable#tally" do
-    before :each do
-      ScratchPad.record []
-    end
-
-    it "returns a hash with counts according to the value" do
-      enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
-      enum.tally.should == { 'foo' => 2, 'bar' => 1, 'baz' => 1}
-    end
-
-    it "returns a hash without default" do
-      hash = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz').tally
-      hash.default_proc.should be_nil
-      hash.default.should be_nil
-    end
-
-    it "returns an empty hash for empty enumerables" do
-      EnumerableSpecs::Empty.new.tally.should == {}
-    end
-
-    it "counts values as gathered array when yielded with multiple arguments" do
-      EnumerableSpecs::YieldsMixed2.new.tally.should == EnumerableSpecs::YieldsMixed2.gathered_yields.group_by(&:itself).transform_values(&:size)
-    end
-
-    it "does not call given block" do
-      enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
-      enum.tally { |v| ScratchPad << v }
-      ScratchPad.recorded.should == []
-    end
+describe "Enumerable#tally" do
+  before :each do
+    ScratchPad.record []
+  end
+
+  it "returns a hash with counts according to the value" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally.should == { 'foo' => 2, 'bar' => 1, 'baz' => 1}
+  end
+
+  it "returns a hash without default" do
+    hash = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz').tally
+    hash.default_proc.should == nil
+    hash.default.should == nil
+  end
+
+  it "returns an empty hash for empty enumerables" do
+    EnumerableSpecs::Empty.new.tally.should == {}
+  end
+
+  it "counts values as gathered array when yielded with multiple arguments" do
+    EnumerableSpecs::YieldsMixed2.new.tally.should == EnumerableSpecs::YieldsMixed2.gathered_yields.group_by(&:itself).transform_values(&:size)
+  end
+
+  it "does not call given block" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally { |v| ScratchPad << v }
+    ScratchPad.recorded.should == []
+  end
+end
+
+describe "Enumerable#tally with a hash" do
+  before :each do
+    ScratchPad.record []
+  end
+
+  it "returns a hash with counts according to the value" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally({ 'foo' => 1 }).should == { 'foo' => 3, 'bar' => 1, 'baz' => 1}
+  end
+
+  it "returns the given hash" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    hash = { 'foo' => 1 }
+    enum.tally(hash).should.equal?(hash)
+  end
+
+  it "calls #to_hash to convert argument to Hash implicitly if passed not a Hash" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    object = Object.new
+    def object.to_hash; { 'foo' => 1 }; end
+    enum.tally(object).should == { 'foo' => 3, 'bar' => 1, 'baz' => 1}
+  end
+
+  it "raises a FrozenError and does not update the given hash when the hash is frozen" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    hash = { 'foo' => 1 }.freeze
+    -> { enum.tally(hash) }.should.raise(FrozenError)
+    hash.should == { 'foo' => 1 }
+  end
+
+  it "raises a FrozenError even if enumerable is empty" do
+    enum = EnumerableSpecs::Numerous.new()
+    hash = { 'foo' => 1 }.freeze
+    -> { enum.tally(hash) }.should.raise(FrozenError)
+  end
+
+  it "does not call given block" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally({ 'foo' => 1 }) { |v| ScratchPad << v }
+    ScratchPad.recorded.should == []
+  end
+
+  it "ignores the default value" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally(Hash.new(100)).should == { 'foo' => 2, 'bar' => 1, 'baz' => 1}
+  end
+
+  it "ignores the default proc" do
+    enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+    enum.tally(Hash.new {100}).should == { 'foo' => 2, 'bar' => 1, 'baz' => 1}
+  end
+
+  it "needs the values counting each elements to be an integer" do
+    enum = EnumerableSpecs::Numerous.new('foo')
+    -> { enum.tally({ 'foo' => 'bar' }) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/enumerable/to_a_spec.rb b/spec/ruby/core/enumerable/to_a_spec.rb
index 0f3060dc48..723f922574 100644
--- a/spec/ruby/core/enumerable/to_a_spec.rb
+++ b/spec/ruby/core/enumerable/to_a_spec.rb
@@ -3,5 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/entries'
 
 describe "Enumerable#to_a" do
-  it_behaves_like :enumerable_entries , :to_a
+  it_behaves_like :enumerable_entries, :to_a
 end
diff --git a/spec/ruby/core/enumerable/to_h_spec.rb b/spec/ruby/core/enumerable/to_h_spec.rb
index 63bfdf19af..38847eccfb 100644
--- a/spec/ruby/core/enumerable/to_h_spec.rb
+++ b/spec/ruby/core/enumerable/to_h_spec.rb
@@ -36,55 +36,61 @@ describe "Enumerable#to_h" do
 
   it "raises TypeError if an element is not an array" do
     enum = EnumerableSpecs::EachDefiner.new(:x)
-    -> { enum.to_h }.should raise_error(TypeError)
+    -> { enum.to_h }.should.raise(TypeError)
   end
 
   it "raises ArgumentError if an element is not a [key, value] pair" do
     enum = EnumerableSpecs::EachDefiner.new([:x])
-    -> { enum.to_h }.should raise_error(ArgumentError)
+    -> { enum.to_h }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      before do
-        @enum = EnumerableSpecs::EachDefiner.new(:a, :b)
-      end
-
-      it "converts [key, value] pairs returned by the block to a hash" do
-        @enum.to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          @enum.to_h { |k| [k, k.to_s, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          @enum.to_h { |k| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          @enum.to_h { |k| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        @enum.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          @enum.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    before do
+      @enum = EnumerableSpecs::EachDefiner.new(:a, :b)
+    end
+
+    it "converts [key, value] pairs returned by the block to a hash" do
+      @enum.to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
+    end
+
+    it "passes to a block each element as a single argument" do
+      enum_of_arrays = EnumerableSpecs::EachDefiner.new([:a, 1], [:b, 2])
+
+      ScratchPad.record []
+      enum_of_arrays.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[[:a, 1]], [[:b, 2]]]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        @enum.to_h { |k| [k, k.to_s, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        @enum.to_h { |k| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        @enum.to_h { |k| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      @enum.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        @enum.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerable/to_set_spec.rb b/spec/ruby/core/enumerable/to_set_spec.rb
new file mode 100644
index 0000000000..7b04c72bce
--- /dev/null
+++ b/spec/ruby/core/enumerable/to_set_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Enumerable#to_set" do
+  it "returns a new Set created from self" do
+    [1, 2, 3].to_set.should == Set[1, 2, 3]
+    {a: 1, b: 2}.to_set.should == Set[[:b, 2], [:a, 1]]
+  end
+
+  it "passes down passed blocks" do
+    [1, 2, 3].to_set { |x| x * x }.should == Set[1, 4, 9]
+  end
+
+  ruby_version_is "4.0"..."4.1" do
+    it "instantiates an object of provided as the first argument set class" do
+      set = nil
+      proc{set = [1, 2, 3].to_set(EnumerableSpecs::SetSubclass)}.should complain(/Enumerable#to_set/)
+      set.should.is_a?(EnumerableSpecs::SetSubclass)
+      set.to_a.sort.should == [1, 2, 3]
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "instantiates an object of provided as the first argument set class" do
+      set = [1, 2, 3].to_set(EnumerableSpecs::SetSubclass)
+      set.should.is_a?(EnumerableSpecs::SetSubclass)
+      set.to_a.sort.should == [1, 2, 3]
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerable/uniq_spec.rb b/spec/ruby/core/enumerable/uniq_spec.rb
index c286882e92..a1ed44796f 100644
--- a/spec/ruby/core/enumerable/uniq_spec.rb
+++ b/spec/ruby/core/enumerable/uniq_spec.rb
@@ -37,10 +37,6 @@ describe 'Enumerable#uniq' do
       obj.should_receive(:hash).at_least(1).and_return(0)
 
       def obj.eql?(o)
-        # It's undefined whether the impl does a[0].eql?(a[1]) or
-        # a[1].eql?(a[0]) so we taint both.
-        taint
-        o.taint
         false
       end
 
@@ -48,18 +44,12 @@ describe 'Enumerable#uniq' do
     end
 
     a.uniq.should == a
-    a[0].tainted?.should == true
-    a[1].tainted?.should == true
 
     a = Array.new(2) do
       obj = mock('0')
       obj.should_receive(:hash).at_least(1).and_return(0)
 
       def obj.eql?(o)
-        # It's undefined whether the impl does a[0].eql?(a[1]) or
-        # a[1].eql?(a[0]) so we taint both.
-        taint
-        o.taint
         true
       end
 
@@ -67,8 +57,6 @@ describe 'Enumerable#uniq' do
     end
 
     a.to_enum.uniq.size.should == 1
-    a[0].tainted?.should == true
-    a[1].tainted?.should == true
   end
 
   context 'when yielded with multiple arguments' do
diff --git a/spec/ruby/core/enumerable/zip_spec.rb b/spec/ruby/core/enumerable/zip_spec.rb
index 9ec15aa030..c5f9a3e4d4 100644
--- a/spec/ruby/core/enumerable/zip_spec.rb
+++ b/spec/ruby/core/enumerable/zip_spec.rb
@@ -38,4 +38,9 @@ describe "Enumerable#zip" do
     multi.zip(multi).should == [[[1, 2], [1, 2]], [[3, 4, 5], [3, 4, 5]], [[6, 7, 8, 9], [6, 7, 8, 9]]]
   end
 
+  it "raises TypeError when some argument isn't Array and doesn't respond to #to_ary and #to_enum" do
+    -> { EnumerableSpecs::Numerous.new(1,2,3).zip(Object.new) }.should.raise(TypeError, "wrong argument type Object (must respond to :each)")
+    -> { EnumerableSpecs::Numerous.new(1,2,3).zip(1) }.should.raise(TypeError, "wrong argument type Integer (must respond to :each)")
+    -> { EnumerableSpecs::Numerous.new(1,2,3).zip(true) }.should.raise(TypeError, "wrong argument type TrueClass (must respond to :each)")
+  end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
index c8d91ebaec..bd243fa0b5 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
@@ -1,11 +1,16 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#begin" do
-    it "returns the begin of the sequence" do
-      1.step(10).begin.should == 1
-      (1..10).step.begin.should == 1
-      (1...10).step.begin.should == 1
+describe "Enumerator::ArithmeticSequence#begin" do
+  it "returns the begin of the sequence" do
+    1.step(10).begin.should == 1
+    (1..10).step.begin.should == 1
+    (1...10).step.begin.should == 1
+  end
+
+  context "with beginless" do
+    it "returns nil as begin of the sequence" do
+      (..10).step(1).begin.should == nil
+      (...10).step(1).begin.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
index d7edf3a21f..0a83019d49 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#each" do
-    before :each do
-      ScratchPad.record []
-      @seq = 1.step(10, 4)
-    end
+describe "Enumerator::ArithmeticSequence#each" do
+  before :each do
+    ScratchPad.record []
+    @seq = 1.step(10, 4)
+  end
 
-    it "calls given block on each item of the sequence" do
-      @seq.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 5, 9]
-    end
+  it "calls given block on each item of the sequence" do
+    @seq.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 5, 9]
+  end
 
-    it "returns self" do
-      @seq.each { |item| }.should equal(@seq)
-    end
+  it "returns self" do
+    @seq.each { |item| }.should.equal?(@seq)
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
index 5a436e8167..05429cac3e 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
@@ -1,11 +1,16 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#end" do
-    it "returns the end of the sequence" do
-      1.step(10).end.should == 10
-      (1..10).step.end.should == 10
-      (1...10).step(17).end.should == 10
+describe "Enumerator::ArithmeticSequence#end" do
+  it "returns the end of the sequence" do
+    1.step(10).end.should == 10
+    (1..10).step.end.should == 10
+    (1...10).step(17).end.should == 10
+  end
+
+  context "with endless" do
+    it "returns nil as end of the sequence" do
+      (1..).step(1).end.should == nil
+      (1...).step(1).end.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
index 7895f98047..77eed02d8b 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
@@ -1,20 +1,18 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#==" do
-    it "returns true if begin, end, step and exclude_end? are equal" do
-      1.step(10).should == 1.step(10)
-      1.step(10, 5).should == 1.step(10, 5)
+describe "Enumerator::ArithmeticSequence#==" do
+  it "returns true if begin, end, step and exclude_end? are equal" do
+    1.step(10).should == 1.step(10)
+    1.step(10, 5).should == 1.step(10, 5)
 
-      (1..10).step.should == (1..10).step
-      (1...10).step(8).should == (1...10).step(8)
+    (1..10).step.should == (1..10).step
+    (1...10).step(8).should == (1...10).step(8)
 
-      # both have exclude_end? == false
-      (1..10).step(100).should == 1.step(10, 100)
+    # both have exclude_end? == false
+    (1..10).step(100).should == 1.step(10, 100)
 
-      ((1..10).step == (1..11).step).should == false
-      ((1..10).step == (1...10).step).should == false
-      ((1..10).step == (1..10).step(2)).should == false
-    end
+    ((1..10).step == (1..11).step).should == false
+    ((1..10).step == (1...10).step).should == false
+    ((1..10).step == (1..10).step(2)).should == false
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
index 8ce0ce0cd9..021fe7d90f 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#exclude_end?" do
-    context "when created using Numeric#step" do
-      it "always returns false" do
-        1.step(10).exclude_end?.should == false
-        10.step(1).exclude_end?.should == false
-      end
+describe "Enumerator::ArithmeticSequence#exclude_end?" do
+  context "when created using Numeric#step" do
+    it "always returns false" do
+      1.step(10).should_not.exclude_end?
+      10.step(1).should_not.exclude_end?
     end
+  end
 
-    context "when created using Range#step" do
-      it "mirrors range.exclude_end?" do
-        (1...10).step.exclude_end?.should == true
-        (1..10).step.exclude_end?.should == false
-      end
+  context "when created using Range#step" do
+    it "mirrors range.exclude_end?" do
+      (1...10).step.should.exclude_end?
+      (1..10).step.should_not.exclude_end?
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
index 43c520d1f0..ccd02be020 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#first" do
-    it "returns the first element of the sequence" do
-      1.step(10).first.should == 1
-      (1..10).step.first.should == 1
-      (1...10).step.first.should == 1
-    end
+describe "Enumerator::ArithmeticSequence#first" do
+  it "returns the first element of the sequence" do
+    1.step(10).first.should == 1
+    (1..10).step.first.should == 1
+    (1...10).step.first.should == 1
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
index 236f845f41..a18c554fb3 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
@@ -1,22 +1,20 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#hash" do
-    it "is based on begin, end, step and exclude_end?" do
-      1.step(10).hash.should be_an_instance_of(Integer)
+describe "Enumerator::ArithmeticSequence#hash" do
+  it "is based on begin, end, step and exclude_end?" do
+    1.step(10).hash.should.instance_of?(Integer)
 
-      1.step(10).hash.should == 1.step(10).hash
-      1.step(10, 5).hash.should == 1.step(10, 5).hash
+    1.step(10).hash.should == 1.step(10).hash
+    1.step(10, 5).hash.should == 1.step(10, 5).hash
 
-      (1..10).step.hash.should == (1..10).step.hash
-      (1...10).step(8).hash.should == (1...10).step(8).hash
+    (1..10).step.hash.should == (1..10).step.hash
+    (1...10).step(8).hash.should == (1...10).step(8).hash
 
-      # both have exclude_end? == false
-      (1..10).step(100).hash.should == 1.step(10, 100).hash
+    # both have exclude_end? == false
+    (1..10).step(100).hash.should == 1.step(10, 100).hash
 
-      ((1..10).step.hash == (1..11).step.hash).should == false
-      ((1..10).step.hash == (1...10).step.hash).should == false
-      ((1..10).step.hash == (1..10).step(2).hash).should == false
-    end
+    ((1..10).step.hash == (1..11).step.hash).should == false
+    ((1..10).step.hash == (1...10).step.hash).should == false
+    ((1..10).step.hash == (1..10).step(2).hash).should == false
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
index 21e64a6b58..b73b49d272 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
@@ -1,22 +1,20 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#inspect" do
-    context 'when Numeric#step is used' do
-      it "returns '(begin.step(end{, step}))'" do
-        1.step(10).inspect.should == "(1.step(10))"
-        1.step(10, 3).inspect.should == "(1.step(10, 3))"
-      end
+describe "Enumerator::ArithmeticSequence#inspect" do
+  context 'when Numeric#step is used' do
+    it "returns '(begin.step(end{, step}))'" do
+      1.step(10).inspect.should == "(1.step(10))"
+      1.step(10, 3).inspect.should == "(1.step(10, 3))"
     end
+  end
 
-    context 'when Range#step is used' do
-      it "returns '((range).step{(step)})'" do
-        (1..10).step.inspect.should == "((1..10).step)"
-        (1..10).step(3).inspect.should == "((1..10).step(3))"
+  context 'when Range#step is used' do
+    it "returns '((range).step{(step)})'" do
+      (1..10).step.inspect.should == "((1..10).step)"
+      (1..10).step(3).inspect.should == "((1..10).step(3))"
 
-        (1...10).step.inspect.should == "((1...10).step)"
-        (1...10).step(3).inspect.should == "((1...10).step(3))"
-      end
+      (1...10).step.inspect.should == "((1...10).step)"
+      (1...10).step(3).inspect.should == "((1...10).step(3))"
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
index ebb20090fc..31f982b7c4 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#last" do
-    it "returns the last element of the sequence" do
-      1.step(10).last.should == 10
-      (1..10).step.last.should == 10
-      (1...10).step(4).last.should == 9
-    end
+describe "Enumerator::ArithmeticSequence#last" do
+  it "returns the last element of the sequence" do
+    1.step(10).last.should == 10
+    (1..10).step.last.should == 10
+    (1...10).step(4).last.should == 9
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
index 7227581fb9..1bd2f7f0f7 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence.new" do
-    it "is not defined" do
-      -> {
-        Enumerator::ArithmeticSequence.new
-      }.should raise_error(NoMethodError)
-    end
+describe "Enumerator::ArithmeticSequence.new" do
+  it "is not defined" do
+    -> {
+      Enumerator::ArithmeticSequence.new
+    }.should.raise(NoMethodError)
   end
+end
 
-  describe "Enumerator::ArithmeticSequence.allocate" do
-    it "is not defined" do
-      -> {
-        Enumerator::ArithmeticSequence.allocate
-      }.should raise_error(TypeError, 'allocator undefined for Enumerator::ArithmeticSequence')
-    end
+describe "Enumerator::ArithmeticSequence.allocate" do
+  it "is not defined" do
+    -> {
+      Enumerator::ArithmeticSequence.allocate
+    }.should.raise(TypeError, 'allocator undefined for Enumerator::ArithmeticSequence')
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
index 00403b0238..7e03edd961 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#size" do
-    context "for finite sequence" do
-      it "returns the number of elements in this arithmetic sequence" do
-        1.step(10).size.should == 10
-        (1...10).step.size.should == 9
-      end
+describe "Enumerator::ArithmeticSequence#size" do
+  context "for finite sequence" do
+    it "returns the number of elements in this arithmetic sequence" do
+      1.step(10).size.should == 10
+      (1...10).step.size.should == 9
     end
+  end
 
-    context "for infinite sequence" do
-      it "returns Infinity" do
-        1.step(Float::INFINITY).size.should == Float::INFINITY
-        (1..Float::INFINITY).step.size.should == Float::INFINITY
-      end
+  context "for infinite sequence" do
+    it "returns Infinity" do
+      1.step(Float::INFINITY).size.should == Float::INFINITY
+      (1..Float::INFINITY).step.size.should == Float::INFINITY
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
index 20a5cb6e7b..c1f2d9173f 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
@@ -1,15 +1,11 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#step" do
-    it "returns the original value given to step method" do
-      (1..10).step.step.should == 1
-      (1..10).step(3).step.should == 3
-      (1..10).step(0).step.should == 0
+describe "Enumerator::ArithmeticSequence#step" do
+  it "returns the original value given to step method" do
+    (1..10).step.step.should == 1
+    (1..10).step(3).step.should == 3
 
-      1.step(10).step.should == 1
-      1.step(10, 3).step.should == 3
-      1.step(10, 0).step.should == 0
-    end
+    1.step(10).step.should == 1
+    1.step(10, 3).step.should == 3
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/each_spec.rb b/spec/ruby/core/enumerator/chain/each_spec.rb
index ab4d355f22..cc93cbac60 100644
--- a/spec/ruby/core/enumerator/chain/each_spec.rb
+++ b/spec/ruby/core/enumerator/chain/each_spec.rb
@@ -1,17 +1,15 @@
 require_relative '../../../spec_helper'
 require_relative '../../enumerable/fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#each" do
-    it "calls each on its constituents as needed" do
-      a = EnumerableSpecs::EachCounter.new(:a, :b)
-      b = EnumerableSpecs::EachCounter.new(:c, :d)
+describe "Enumerator::Chain#each" do
+  it "calls each on its constituents as needed" do
+    a = EnumerableSpecs::EachCounter.new(:a, :b)
+    b = EnumerableSpecs::EachCounter.new(:c, :d)
 
-      ScratchPad.record []
-      Enumerator::Chain.new(a, b).each do |elem|
-        ScratchPad << elem << b.times_yielded
-      end
-      ScratchPad.recorded.should == [:a, 0, :b, 0, :c, 1, :d, 2]
+    ScratchPad.record []
+    Enumerator::Chain.new(a, b).each do |elem|
+      ScratchPad << elem << b.times_yielded
     end
+    ScratchPad.recorded.should == [:a, 0, :b, 0, :c, 1, :d, 2]
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/initialize_spec.rb b/spec/ruby/core/enumerator/chain/initialize_spec.rb
index e5aa32fd02..1df1dec5f8 100644
--- a/spec/ruby/core/enumerator/chain/initialize_spec.rb
+++ b/spec/ruby/core/enumerator/chain/initialize_spec.rb
@@ -1,33 +1,31 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#initialize" do
-    before :each do
-      @uninitialized = Enumerator::Chain.allocate
-    end
+describe "Enumerator::Chain#initialize" do
+  before :each do
+    @uninitialized = Enumerator::Chain.allocate
+  end
 
-    it "is a private method" do
-      Enumerator::Chain.should have_private_instance_method(:initialize, false)
-    end
+  it "is a private method" do
+    Enumerator::Chain.private_instance_methods(false).should.include?(:initialize)
+  end
 
-    it "returns self" do
-      @uninitialized.send(:initialize).should equal(@uninitialized)
-    end
+  it "returns self" do
+    @uninitialized.send(:initialize).should.equal?(@uninitialized)
+  end
 
-    it "accepts many arguments" do
-      @uninitialized.send(:initialize, 0..1, 2..3, 4..5).should equal(@uninitialized)
-    end
+  it "accepts many arguments" do
+    @uninitialized.send(:initialize, 0..1, 2..3, 4..5).should.equal?(@uninitialized)
+  end
 
-    it "accepts arguments that are not Enumerable nor responding to :each" do
-      @uninitialized.send(:initialize, Object.new).should equal(@uninitialized)
-    end
+  it "accepts arguments that are not Enumerable nor responding to :each" do
+    @uninitialized.send(:initialize, Object.new).should.equal?(@uninitialized)
+  end
 
-    describe "on frozen instance" do
-      it "raises a RuntimeError" do
-        -> {
-          @uninitialized.freeze.send(:initialize)
-        }.should raise_error(RuntimeError)
-      end
+  describe "on frozen instance" do
+    it "raises a FrozenError" do
+      -> {
+        @uninitialized.freeze.send(:initialize)
+      }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/inspect_spec.rb b/spec/ruby/core/enumerator/chain/inspect_spec.rb
index a644d88c6f..9b5a442b75 100644
--- a/spec/ruby/core/enumerator/chain/inspect_spec.rb
+++ b/spec/ruby/core/enumerator/chain/inspect_spec.rb
@@ -1,16 +1,18 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#inspect" do
-    it "shows a representation of the Enumerator" do
-      Enumerator::Chain.new.inspect.should == "#<Enumerator::Chain: []>"
-      Enumerator::Chain.new(1..2, 3..4).inspect.should == "#<Enumerator::Chain: [1..2, 3..4]>"
-    end
+describe "Enumerator::Chain#inspect" do
+  it "shows a representation of the Enumerator" do
+    Enumerator::Chain.new.inspect.should == "#<Enumerator::Chain: []>"
+    Enumerator::Chain.new(1..2, 3..4).inspect.should == "#<Enumerator::Chain: [1..2, 3..4]>"
+  end
+
+  it "calls inspect on its chain elements" do
+    obj = mock('inspect')
+    obj.should_receive(:inspect).and_return('some desc')
+    Enumerator::Chain.new(obj).inspect.should == "#<Enumerator::Chain: [some desc]>"
+  end
 
-    it "calls inspect on its chain elements" do
-      obj = mock('inspect')
-      obj.should_receive(:inspect).and_return('some desc')
-      Enumerator::Chain.new(obj).inspect.should == "#<Enumerator::Chain: [some desc]>"
-    end
+  it "returns a not initialized representation if #initialized is not called yet" do
+    Enumerator::Chain.allocate.inspect.should == "#<Enumerator::Chain: uninitialized>"
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/rewind_spec.rb b/spec/ruby/core/enumerator/chain/rewind_spec.rb
index 951b364f07..4525b82f7b 100644
--- a/spec/ruby/core/enumerator/chain/rewind_spec.rb
+++ b/spec/ruby/core/enumerator/chain/rewind_spec.rb
@@ -1,53 +1,51 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#rewind" do
-    before(:each) do
-      @obj = mock('obj')
-      @obj.should_receive(:each).any_number_of_times.and_yield
-      @second = mock('obj')
-      @second.should_receive(:each).any_number_of_times.and_yield
-      @enum = Enumerator::Chain.new(@obj, @second)
-    end
-
-    it "returns self" do
-      @enum.rewind.should equal @enum
-    end
-
-    it "does nothing if receiver has not been iterated" do
-      @obj.should_not_receive(:rewind)
-      @obj.respond_to?(:rewind).should == true # sanity check
-      @enum.rewind
-    end
-
-    it "does nothing on objects that don't respond_to rewind" do
-      @obj.respond_to?(:rewind).should == false # sanity check
-      @enum.each {}
-      @enum.rewind
-    end
-
-    it "calls_rewind its objects" do
-      @obj.should_receive(:rewind)
-      @enum.each {}
-      @enum.rewind
-    end
-
-    it "calls_rewind in reverse order" do
-      @obj.should_not_receive(:rewind)
-      @second.should_receive(:rewind).and_raise(RuntimeError)
-      @enum.each {}
-      -> { @enum.rewind }.should raise_error(RuntimeError)
-    end
-
-    it "calls rewind only for objects that have actually been iterated on" do
-      @obj = mock('obj')
-      @obj.should_receive(:each).any_number_of_times.and_raise(RuntimeError)
-      @enum = Enumerator::Chain.new(@obj, @second)
-
-      @obj.should_receive(:rewind)
-      @second.should_not_receive(:rewind)
-      -> { @enum.each {} }.should raise_error(RuntimeError)
-      @enum.rewind
-    end
+describe "Enumerator::Chain#rewind" do
+  before(:each) do
+    @obj = mock('obj')
+    @obj.should_receive(:each).any_number_of_times.and_yield
+    @second = mock('obj')
+    @second.should_receive(:each).any_number_of_times.and_yield
+    @enum = Enumerator::Chain.new(@obj, @second)
+  end
+
+  it "returns self" do
+    @enum.rewind.should.equal? @enum
+  end
+
+  it "does nothing if receiver has not been iterated" do
+    @obj.should_not_receive(:rewind)
+    @obj.respond_to?(:rewind).should == true # sanity check
+    @enum.rewind
+  end
+
+  it "does nothing on objects that don't respond_to rewind" do
+    @obj.respond_to?(:rewind).should == false # sanity check
+    @enum.each {}
+    @enum.rewind
+  end
+
+  it "calls_rewind its objects" do
+    @obj.should_receive(:rewind)
+    @enum.each {}
+    @enum.rewind
+  end
+
+  it "calls_rewind in reverse order" do
+    @obj.should_not_receive(:rewind)
+    @second.should_receive(:rewind).and_raise(RuntimeError)
+    @enum.each {}
+    -> { @enum.rewind }.should.raise(RuntimeError)
+  end
+
+  it "calls rewind only for objects that have actually been iterated on" do
+    @obj = mock('obj')
+    @obj.should_receive(:each).any_number_of_times.and_raise(RuntimeError)
+    @enum = Enumerator::Chain.new(@obj, @second)
+
+    @obj.should_receive(:rewind)
+    @second.should_not_receive(:rewind)
+    -> { @enum.each {} }.should.raise(RuntimeError)
+    @enum.rewind
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/size_spec.rb b/spec/ruby/core/enumerator/chain/size_spec.rb
index 42c31ac10b..d85b88ee8b 100644
--- a/spec/ruby/core/enumerator/chain/size_spec.rb
+++ b/spec/ruby/core/enumerator/chain/size_spec.rb
@@ -1,24 +1,22 @@
 require_relative '../../../spec_helper'
 require_relative '../../enumerable/fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#size" do
-    it "returns the sum of the sizes of the elements" do
+describe "Enumerator::Chain#size" do
+  it "returns the sum of the sizes of the elements" do
+    a = mock('size')
+    a.should_receive(:size).and_return(40)
+    Enumerator::Chain.new(a, [:a, :b]).size.should == 42
+  end
+
+  it "returns nil or Infinity for the first element of such a size" do
+    [nil, Float::INFINITY].each do |special|
       a = mock('size')
       a.should_receive(:size).and_return(40)
-      Enumerator::Chain.new(a, [:a, :b]).size.should == 42
-    end
-
-    it "returns nil or Infinity for the first element of such a size" do
-      [nil, Float::INFINITY].each do |special|
-        a = mock('size')
-        a.should_receive(:size).and_return(40)
-        b = mock('special')
-        b.should_receive(:size).and_return(special)
-        c = mock('not called')
-        c.should_not_receive(:size)
-        Enumerator::Chain.new(a, b, c).size.should == special
-      end
+      b = mock('special')
+      b.should_receive(:size).and_return(special)
+      c = mock('not called')
+      c.should_not_receive(:size)
+      Enumerator::Chain.new(a, b, c).size.should == special
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/each_spec.rb b/spec/ruby/core/enumerator/each_spec.rb
index d88c09cdb5..03be53fe05 100644
--- a/spec/ruby/core/enumerator/each_spec.rb
+++ b/spec/ruby/core/enumerator/each_spec.rb
@@ -10,58 +10,58 @@ describe "Enumerator#each" do
 
     @enum_with_arguments = object_each_with_arguments.to_enum(:each_with_arguments, :arg0, :arg1, :arg2)
 
-    @enum_with_yielder = Enumerator.new {|y| y.yield :ok}
+    @enum_with_yielder = Enumerator.new { |y| y.yield :ok }
   end
 
   it "yields each element of self to the given block" do
     acc = []
-    [1,2,3].to_enum.each {|e| acc << e }
-    acc.should == [1,2,3]
+    [1, 2, 3].to_enum.each { |e| acc << e }
+    acc.should == [1, 2, 3]
   end
 
   it "calls #each on the object given in the constructor by default" do
     each = mock('each')
     each.should_receive(:each)
-    each.to_enum.each {|e| e }
+    each.to_enum.each { |e| e }
   end
 
   it "calls #each on the underlying object until it's exhausted" do
     each = mock('each')
     each.should_receive(:each).and_yield(1).and_yield(2).and_yield(3)
     acc = []
-    each.to_enum.each {|e| acc << e }
-    acc.should == [1,2,3]
+    each.to_enum.each { |e| acc << e }
+    acc.should == [1, 2, 3]
   end
 
   it "calls the method given in the constructor instead of #each" do
     each = mock('peach')
     each.should_receive(:peach)
-    each.to_enum(:peach).each {|e| e }
+    each.to_enum(:peach).each { |e| e }
   end
 
   it "calls the method given in the constructor until it's exhausted" do
-    each = mock('each')
-    each.should_receive(:each).and_yield(1).and_yield(2).and_yield(3)
+    each = mock('peach')
+    each.should_receive(:peach).and_yield(1).and_yield(2).and_yield(3)
     acc = []
-    each.to_enum.each {|e| acc << e }
-    acc.should == [1,2,3]
+    each.to_enum(:peach).each { |e| acc << e }
+    acc.should == [1, 2, 3]
   end
 
   it "raises a NoMethodError if the object doesn't respond to #each" do
     enum = Object.new.to_enum
     -> do
       enum.each { |e| e }
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "returns self if not given arguments and not given a block" do
-    @enum_with_arguments.each.should equal(@enum_with_arguments)
+    @enum_with_arguments.each.should.equal?(@enum_with_arguments)
 
-    @enum_with_yielder.each.should equal(@enum_with_yielder)
+    @enum_with_yielder.each.should.equal?(@enum_with_yielder)
   end
 
   it "returns the same value from receiver.each if block is given" do
-    @enum_with_arguments.each {}.should equal(:method_returned)
+    @enum_with_arguments.each {}.should.equal?(:method_returned)
   end
 
   it "passes given arguments at initialized to receiver.each" do
@@ -78,12 +78,27 @@ describe "Enumerator#each" do
   end
 
   it "returns the same value from receiver.each if block and arguments are given" do
-    @enum_with_arguments.each(:each1, :each2) {}.should equal(:method_returned)
+    @enum_with_arguments.each(:each1, :each2) {}.should.equal?(:method_returned)
   end
 
   it "returns new Enumerator if given arguments but not given a block" do
     ret = @enum_with_arguments.each 1
-    ret.should be_an_instance_of(Enumerator)
-    ret.should_not equal(@enum_with_arguments)
+    ret.should.instance_of?(Enumerator)
+    ret.should_not.equal?(@enum_with_arguments)
+  end
+
+  it "does not destructure yielded array values when chaining each.map" do
+    result = [[[1]]].each.map { |a, b| [a, b] }
+    result.should == [[[1], nil]]
+  end
+
+  it "preserves array values yielded from the enumerator" do
+    result = [[1, 2]].each.map { |a| a }
+    result.should == [[1, 2]]
+  end
+
+  it "allows destructuring to occur in the block, not the enumerator" do
+    result = [[1, 2]].each.map { |a, b| a }
+    result.should == [1]
   end
 end
diff --git a/spec/ruby/core/enumerator/each_with_index_spec.rb b/spec/ruby/core/enumerator/each_with_index_spec.rb
index 96e53a2804..0630b7045e 100644
--- a/spec/ruby/core/enumerator/each_with_index_spec.rb
+++ b/spec/ruby/core/enumerator/each_with_index_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/with_index'
+require_relative 'shared/with_index'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Enumerator#each_with_index" do
@@ -9,28 +9,28 @@ describe "Enumerator#each_with_index" do
   it "returns a new Enumerator when no block is given" do
     enum1 = [1,2,3].select
     enum2 = enum1.each_with_index
-    enum2.should be_an_instance_of(Enumerator)
+    enum2.should.instance_of?(Enumerator)
     enum1.should_not == enum2
   end
 
   it "raises an ArgumentError if passed extra arguments" do
     -> do
       [1].to_enum.each_with_index(:glark)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "passes on the given block's return value" do
     arr = [1,2,3]
-    arr.delete_if.with_index { |a,b| false }
+    arr.delete_if.each_with_index { |a,b| false }
     arr.should == [1,2,3]
   end
 
   it "returns the iterator's return value" do
-    [1,2,3].select.with_index { |a,b| false }.should == []
+    [1,2,3].select.each_with_index { |a,b| false }.should == []
+    [1,2,3].select.each_with_index { |a,b| true }.should == [1,2,3]
   end
 
   it "returns the correct value if chained with itself" do
     [:a].each_with_index.each_with_index.to_a.should == [[[:a,0],0]]
-    [:a].each.with_index.with_index.to_a.should == [[[:a,0],0]]
   end
 end
diff --git a/spec/ruby/core/enumerator/each_with_object_spec.rb b/spec/ruby/core/enumerator/each_with_object_spec.rb
index 68524dc74a..84a45ae89d 100644
--- a/spec/ruby/core/enumerator/each_with_object_spec.rb
+++ b/spec/ruby/core/enumerator/each_with_object_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/with_object'
+require_relative 'shared/with_object'
 
 describe "Enumerator#each_with_object" do
   it_behaves_like :enum_with_object, :each_with_object
diff --git a/spec/ruby/core/enumerator/enum_for_spec.rb b/spec/ruby/core/enumerator/enum_for_spec.rb
index fd33f463bf..fbdf98545a 100644
--- a/spec/ruby/core/enumerator/enum_for_spec.rb
+++ b/spec/ruby/core/enumerator/enum_for_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/enum_for'
+require_relative 'shared/enum_for'
 
 describe "Enumerator#enum_for" do
   it_behaves_like :enum_for, :enum_for
diff --git a/spec/ruby/core/enumerator/feed_spec.rb b/spec/ruby/core/enumerator/feed_spec.rb
index e387c6cd39..781947a8c7 100644
--- a/spec/ruby/core/enumerator/feed_spec.rb
+++ b/spec/ruby/core/enumerator/feed_spec.rb
@@ -33,20 +33,20 @@ describe "Enumerator#feed" do
   end
 
   it "returns nil" do
-    @enum.feed(:a).should be_nil
+    @enum.feed(:a).should == nil
   end
 
   it "raises a TypeError if called more than once without advancing the enumerator" do
     @enum.feed :a
     @enum.next
-    -> { @enum.feed :b }.should raise_error(TypeError)
+    -> { @enum.feed :b }.should.raise(TypeError)
   end
 
   it "sets the return value of Yielder#yield" do
     enum = Enumerator.new { |y| ScratchPad << y.yield }
     enum.next
     enum.feed :a
-    -> { enum.next }.should raise_error(StopIteration)
+    -> { enum.next }.should.raise(StopIteration)
     ScratchPad.recorded.should == [:a]
   end
 end
diff --git a/spec/ruby/fixtures/enumerator/classes.rb b/spec/ruby/core/enumerator/fixtures/classes.rb
index 6f285b8efa..6f285b8efa 100644
--- a/spec/ruby/fixtures/enumerator/classes.rb
+++ b/spec/ruby/core/enumerator/fixtures/classes.rb
diff --git a/spec/ruby/core/enumerator/generator/each_spec.rb b/spec/ruby/core/enumerator/generator/each_spec.rb
deleted file mode 100644
index a43805dd16..0000000000
--- a/spec/ruby/core/enumerator/generator/each_spec.rb
+++ /dev/null
@@ -1,40 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Enumerator::Generator#each" do
-  before :each do
-    @generator = Enumerator::Generator.new do |y, *args|
-      y << 3 << 2 << 1
-      y << args unless args.empty?
-      :block_returned
-    end
-  end
-
-  it "is an enumerable" do
-    @generator.should be_kind_of(Enumerable)
-  end
-
-  it "supports enumeration with a block" do
-    r = []
-    @generator.each { |v| r << v }
-
-    r.should == [3, 2, 1]
-  end
-
-  it "raises a LocalJumpError if no block given" do
-    -> { @generator.each }.should raise_error(LocalJumpError)
-  end
-
-  it "returns the block returned value" do
-    @generator.each {}.should equal(:block_returned)
-  end
-
-  it "requires multiple arguments" do
-    Enumerator::Generator.instance_method(:each).arity.should < 0
-  end
-
-  it "appends given arguments to receiver.each" do
-    yields = []
-    @generator.each(:each0, :each1) { |yielded| yields << yielded }
-    yields.should == [3, 2, 1, [:each0, :each1]]
-  end
-end
diff --git a/spec/ruby/core/enumerator/generator/initialize_spec.rb b/spec/ruby/core/enumerator/generator/initialize_spec.rb
deleted file mode 100644
index f75c7d6f26..0000000000
--- a/spec/ruby/core/enumerator/generator/initialize_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-# -*- encoding: us-ascii -*-
-
-require_relative '../../../spec_helper'
-
-describe "Enumerator::Generator#initialize" do
-  before :each do
-    @class = Enumerator::Generator
-    @uninitialized = @class.allocate
-  end
-
-  it "is a private method" do
-    @class.should have_private_instance_method(:initialize, false)
-  end
-
-  it "returns self when given a block" do
-    @uninitialized.send(:initialize) {}.should equal(@uninitialized)
-  end
-
-  describe "on frozen instance" do
-    it "raises a RuntimeError" do
-      -> {
-        @uninitialized.freeze.send(:initialize) {}
-      }.should raise_error(RuntimeError)
-    end
-  end
-end
diff --git a/spec/ruby/core/enumerator/initialize_spec.rb b/spec/ruby/core/enumerator/initialize_spec.rb
index 53bf5d4ef2..9929494b5a 100644
--- a/spec/ruby/core/enumerator/initialize_spec.rb
+++ b/spec/ruby/core/enumerator/initialize_spec.rb
@@ -8,15 +8,11 @@ describe "Enumerator#initialize" do
   end
 
   it "is a private method" do
-    Enumerator.should have_private_instance_method(:initialize, false)
-  end
-
-  it "returns self when given an object" do
-    @uninitialized.send(:initialize, Object.new).should equal(@uninitialized)
+    Enumerator.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "returns self when given a block" do
-    @uninitialized.send(:initialize) {}.should equal(@uninitialized)
+    @uninitialized.send(:initialize) {}.should.equal?(@uninitialized)
   end
 
   # Maybe spec should be broken up?
@@ -25,25 +21,25 @@ describe "Enumerator#initialize" do
       r = yielder.yield 3
       yielder << r << 2 << 1
     end
-    @uninitialized.should be_an_instance_of(Enumerator)
+    @uninitialized.should.instance_of?(Enumerator)
     r = []
     @uninitialized.each{|x| r << x; x * 2}
     r.should == [3, 6, 2, 1]
   end
 
   it "sets size to nil if size is not given" do
-    @uninitialized.send(:initialize) {}.size.should be_nil
+    @uninitialized.send(:initialize) {}.size.should == nil
   end
 
   it "sets size to nil if the given size is nil" do
-    @uninitialized.send(:initialize, nil) {}.size.should be_nil
+    @uninitialized.send(:initialize, nil) {}.size.should == nil
   end
 
   it "sets size to the given size if the given size is Float::INFINITY" do
-    @uninitialized.send(:initialize, Float::INFINITY) {}.size.should equal(Float::INFINITY)
+    @uninitialized.send(:initialize, Float::INFINITY) {}.size.should.equal?(Float::INFINITY)
   end
 
-  it "sets size to the given size if the given size is a Fixnum" do
+  it "sets size to the given size if the given size is an Integer" do
     @uninitialized.send(:initialize, 100) {}.size.should == 100
   end
 
@@ -52,10 +48,10 @@ describe "Enumerator#initialize" do
   end
 
   describe "on frozen instance" do
-    it "raises a RuntimeError" do
+    it "raises a FrozenError" do
       -> {
         @uninitialized.freeze.send(:initialize) {}
-      }.should raise_error(RuntimeError)
+      }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/inspect_spec.rb b/spec/ruby/core/enumerator/inspect_spec.rb
index 3bcf07e754..7e97864246 100644
--- a/spec/ruby/core/enumerator/inspect_spec.rb
+++ b/spec/ruby/core/enumerator/inspect_spec.rb
@@ -14,4 +14,9 @@ describe "Enumerator#inspect" do
       (1..3).each.each_slice(2).inspect.should == "#<Enumerator: #<Enumerator: 1..3:each>:each_slice(2)>"
     end
   end
+
+  it "returns a not initialized representation if #initialized is not called yet" do
+    Enumerator.allocate.inspect.should == "#<Enumerator: uninitialized>"
+    Enumerator::Lazy.allocate.inspect.should == "#<Enumerator::Lazy: uninitialized>"
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/chunk_spec.rb b/spec/ruby/core/enumerator/lazy/chunk_spec.rb
index 87d2b0c206..d0179d32b6 100644
--- a/spec/ruby/core/enumerator/lazy/chunk_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/chunk_spec.rb
@@ -17,8 +17,8 @@ describe "Enumerator::Lazy#chunk" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.chunk {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -27,7 +27,7 @@ describe "Enumerator::Lazy#chunk" do
 
   it "returns an Enumerator if called without a block" do
     chunk = @yieldsmixed.chunk
-    chunk.should be_an_instance_of(Enumerator::Lazy)
+    chunk.should.instance_of?(Enumerator::Lazy)
 
     res = chunk.each { |v| true }.force
     res.should == [[true, EnumeratorLazySpecs::YieldsMixed.gathered_yields]]
diff --git a/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb b/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
index d555089872..edba8e1363 100644
--- a/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#chunk_while" do
     s.lazy.chunk_while { |a, b| false }.first(100).should ==
       s.first(100).chunk_while { |a, b| false }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.chunk_while { |a, b| false }.should.is_a?(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/compact_spec.rb b/spec/ruby/core/enumerator/lazy/compact_spec.rb
new file mode 100644
index 0000000000..7305e1c9c4
--- /dev/null
+++ b/spec/ruby/core/enumerator/lazy/compact_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Enumerator::Lazy#compact" do
+  it 'returns array without nil elements' do
+    arr = [1, nil, 3, false, 5].to_enum.lazy.compact
+    arr.should.instance_of?(Enumerator::Lazy)
+    arr.force.should == [1, 3, false, 5]
+  end
+
+  it "sets #size to nil" do
+    Enumerator::Lazy.new(Object.new, 100) {}.compact.size.should == nil
+  end
+end
diff --git a/spec/ruby/core/enumerator/lazy/drop_spec.rb b/spec/ruby/core/enumerator/lazy/drop_spec.rb
index 822b8034fb..95ac7e9ecc 100644
--- a/spec/ruby/core/enumerator/lazy/drop_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/drop_spec.rb
@@ -16,8 +16,8 @@ describe "Enumerator::Lazy#drop" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.drop(1)
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets difference of given count with old size to new size" do
diff --git a/spec/ruby/core/enumerator/lazy/drop_while_spec.rb b/spec/ruby/core/enumerator/lazy/drop_while_spec.rb
index 4f6e366f88..65f3007dec 100644
--- a/spec/ruby/core/enumerator/lazy/drop_while_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/drop_while_spec.rb
@@ -16,8 +16,8 @@ describe "Enumerator::Lazy#drop_while" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.drop_while {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -40,7 +40,7 @@ describe "Enumerator::Lazy#drop_while" do
   end
 
   it "raises an ArgumentError when not given a block" do
-    -> { @yieldsmixed.drop_while }.should raise_error(ArgumentError)
+    -> { @yieldsmixed.drop_while }.should.raise(ArgumentError)
   end
 
   describe "on a nested Lazy" do
diff --git a/spec/ruby/core/enumerator/lazy/eager_spec.rb b/spec/ruby/core/enumerator/lazy/eager_spec.rb
new file mode 100644
index 0000000000..592da4fd8c
--- /dev/null
+++ b/spec/ruby/core/enumerator/lazy/eager_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Lazy#eager" do
+  it "returns a non-lazy Enumerator converted from the lazy enumerator" do
+    enum = [1, 2, 3].lazy
+
+    enum.class.should == Enumerator::Lazy
+    enum.eager.class.should == Enumerator
+  end
+
+  it "does not enumerate an enumerator" do
+    ScratchPad.record []
+
+    sequence = [1, 2, 3]
+    enum_lazy = Enumerator::Lazy.new(sequence) do |yielder, value|
+      yielder << value
+      ScratchPad << value
+    end
+
+    ScratchPad.recorded.should == []
+    enum = enum_lazy.eager
+    ScratchPad.recorded.should == []
+
+    enum.map { |i| i }.should == [1, 2, 3]
+    ScratchPad.recorded.should == [1, 2, 3]
+  end
+end
diff --git a/spec/ruby/core/enumerator/lazy/filter_map_spec.rb b/spec/ruby/core/enumerator/lazy/filter_map_spec.rb
new file mode 100644
index 0000000000..99dd59cebe
--- /dev/null
+++ b/spec/ruby/core/enumerator/lazy/filter_map_spec.rb
@@ -0,0 +1,14 @@
+# -*- encoding: us-ascii -*-
+
+require_relative '../../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Enumerator::Lazy#filter_map" do
+  it "maps only truthy results" do
+    (1..Float::INFINITY).lazy.filter_map { |i| i if i.odd? }.first(4).should == [1, 3, 5, 7]
+  end
+
+  it "does not map false results" do
+    (1..Float::INFINITY).lazy.filter_map { |i| i.odd? ? i : false }.first(4).should == [1, 3, 5, 7]
+  end
+end
diff --git a/spec/ruby/core/enumerator/lazy/filter_spec.rb b/spec/ruby/core/enumerator/lazy/filter_spec.rb
index 2ababa69cc..43128241e0 100644
--- a/spec/ruby/core/enumerator/lazy/filter_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/filter_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../../spec_helper'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Lazy#filter" do
-    it_behaves_like :enumerator_lazy_select, :filter
-  end
+describe "Enumerator::Lazy#filter" do
+  it_behaves_like :enumerator_lazy_select, :filter
 end
diff --git a/spec/ruby/core/enumerator/lazy/grep_spec.rb b/spec/ruby/core/enumerator/lazy/grep_spec.rb
index e67686c9a3..383f80a918 100644
--- a/spec/ruby/core/enumerator/lazy/grep_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/grep_spec.rb
@@ -20,12 +20,12 @@ describe "Enumerator::Lazy#grep" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.grep(Object) {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
 
     ret = @yieldsmixed.grep(Object)
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
diff --git a/spec/ruby/core/enumerator/lazy/grep_v_spec.rb b/spec/ruby/core/enumerator/lazy/grep_v_spec.rb
index 67173021bb..19c917f254 100644
--- a/spec/ruby/core/enumerator/lazy/grep_v_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/grep_v_spec.rb
@@ -18,12 +18,12 @@ describe "Enumerator::Lazy#grep_v" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.grep_v(Object) {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
 
     ret = @yieldsmixed.grep_v(Object)
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
diff --git a/spec/ruby/core/enumerator/lazy/initialize_spec.rb b/spec/ruby/core/enumerator/lazy/initialize_spec.rb
index 88c66530b9..47765d32c3 100644
--- a/spec/ruby/core/enumerator/lazy/initialize_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/initialize_spec.rb
@@ -16,11 +16,11 @@ describe "Enumerator::Lazy#initialize" do
   end
 
   it "is a private method" do
-    Enumerator::Lazy.should have_private_instance_method(:initialize, false)
+    Enumerator::Lazy.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "returns self" do
-    @uninitialized.send(:initialize, @receiver) {}.should equal(@uninitialized)
+    @uninitialized.send(:initialize, @receiver) {}.should.equal?(@uninitialized)
   end
 
   describe "when the returned lazy enumerator is evaluated by Enumerable#first" do
@@ -32,18 +32,18 @@ describe "Enumerator::Lazy#initialize" do
   end
 
   it "sets #size to nil if not given a size" do
-    @uninitialized.send(:initialize, @receiver) {}.size.should be_nil
+    @uninitialized.send(:initialize, @receiver) {}.size.should == nil
   end
 
   it "sets #size to nil if given size is nil" do
-    @uninitialized.send(:initialize, @receiver, nil) {}.size.should be_nil
+    @uninitialized.send(:initialize, @receiver, nil) {}.size.should == nil
   end
 
   it "sets given size to own size if the given size is Float::INFINITY" do
-    @uninitialized.send(:initialize, @receiver, Float::INFINITY) {}.size.should equal(Float::INFINITY)
+    @uninitialized.send(:initialize, @receiver, Float::INFINITY) {}.size.should.equal?(Float::INFINITY)
   end
 
-  it "sets given size to own size if the given size is a Fixnum" do
+  it "sets given size to own size if the given size is an Integer" do
     @uninitialized.send(:initialize, @receiver, 100) {}.size.should == 100
   end
 
@@ -52,12 +52,12 @@ describe "Enumerator::Lazy#initialize" do
   end
 
   it "raises an ArgumentError when block is not given" do
-    -> {  @uninitialized.send :initialize, @receiver }.should raise_error(ArgumentError)
+    -> {  @uninitialized.send :initialize, @receiver }.should.raise(ArgumentError)
   end
 
   describe "on frozen instance" do
-    it "raises a RuntimeError" do
-      -> {  @uninitialized.freeze.send(:initialize, @receiver) {} }.should raise_error(RuntimeError)
+    it "raises a FrozenError" do
+      -> {  @uninitialized.freeze.send(:initialize, @receiver) {} }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/lazy/lazy_spec.rb b/spec/ruby/core/enumerator/lazy/lazy_spec.rb
index cde9b31066..12107383d6 100644
--- a/spec/ruby/core/enumerator/lazy/lazy_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/lazy_spec.rb
@@ -4,25 +4,24 @@ require_relative '../../../spec_helper'
 
 describe "Enumerator::Lazy" do
   it "is a subclass of Enumerator" do
-    Enumerator::Lazy.superclass.should equal(Enumerator)
+    Enumerator::Lazy.superclass.should.equal?(Enumerator)
   end
 
   it "defines lazy versions of a whitelist of Enumerator methods" do
-    lazy_methods = [
-      :chunk, :collect, :collect_concat, :drop, :drop_while, :enum_for,
+    lazy_methods = Set[
+      :chunk, :chunk_while, :collect, :collect_concat, :compact, :drop, :drop_while, :enum_for,
       :find_all, :flat_map, :force, :grep, :grep_v, :lazy, :map, :reject,
       :select, :slice_after, :slice_before, :slice_when, :take, :take_while,
-      :to_enum, :zip
+      :to_enum, :uniq, :zip
     ]
-    lazy_methods += [:chunk_while, :uniq]
 
-    Enumerator::Lazy.instance_methods(false).should include(*lazy_methods)
+    Enumerator::Lazy.instance_methods(false).to_set.should >= lazy_methods
   end
 end
 
 describe "Enumerator::Lazy#lazy" do
   it "returns self" do
     lazy = (1..3).to_enum.lazy
-    lazy.lazy.should equal(lazy)
+    lazy.lazy.should.equal?(lazy)
   end
 end
diff --git a/spec/ruby/core/enumerator/lazy/reject_spec.rb b/spec/ruby/core/enumerator/lazy/reject_spec.rb
index 0e1632d667..374d4df14e 100644
--- a/spec/ruby/core/enumerator/lazy/reject_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/reject_spec.rb
@@ -16,8 +16,8 @@ describe "Enumerator::Lazy#reject" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.reject {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -42,7 +42,7 @@ describe "Enumerator::Lazy#reject" do
 
     -> {
       lazy.first
-    }.should raise_error(RuntimeError, "foo")
+    }.should.raise(RuntimeError, "foo")
   end
 
   it "calls the block with a gathered array when yield with multiple arguments" do
@@ -52,7 +52,7 @@ describe "Enumerator::Lazy#reject" do
   end
 
   it "raises an ArgumentError when not given a block" do
-    -> { @yieldsmixed.reject }.should raise_error(ArgumentError)
+    -> { @yieldsmixed.reject }.should.raise(ArgumentError)
   end
 
   describe "on a nested Lazy" do
diff --git a/spec/ruby/core/enumerator/lazy/shared/collect.rb b/spec/ruby/core/enumerator/lazy/shared/collect.rb
index 5690255a0c..0ed04c8e02 100644
--- a/spec/ruby/core/enumerator/lazy/shared/collect.rb
+++ b/spec/ruby/core/enumerator/lazy/shared/collect.rb
@@ -16,8 +16,8 @@ describe :enumerator_lazy_collect, shared: true do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.send(@method) {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "keeps size" do
diff --git a/spec/ruby/core/enumerator/lazy/shared/collect_concat.rb b/spec/ruby/core/enumerator/lazy/shared/collect_concat.rb
index 00d7941a61..685e6d0594 100644
--- a/spec/ruby/core/enumerator/lazy/shared/collect_concat.rb
+++ b/spec/ruby/core/enumerator/lazy/shared/collect_concat.rb
@@ -16,8 +16,8 @@ describe :enumerator_lazy_collect_concat, shared: true do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.send(@method) {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -34,7 +34,7 @@ describe :enumerator_lazy_collect_concat, shared: true do
 
     it "flattens elements when the given block returned an array or responding to .each and .force" do
       (0..Float::INFINITY).lazy.send(@method) { |n| (n * 10).to_s.chars }.first(6).should == %w[0 1 0 2 0 3]
-      (0..Float::INFINITY).lazy.send(@method) { |n| (n * 10).to_s.each_char }.first(6).all? { |o| o.instance_of? Enumerator }.should be_true
+      (0..Float::INFINITY).lazy.send(@method) { |n| (n * 10).to_s.each_char }.first(6).all? { |o| o.instance_of? Enumerator }.should == true
       (0..Float::INFINITY).lazy.send(@method) { |n| (n * 10).to_s.each_char.lazy }.first(6).should == %w[0 1 0 2 0 3]
     end
   end
@@ -46,7 +46,7 @@ describe :enumerator_lazy_collect_concat, shared: true do
   end
 
   it "raises an ArgumentError when not given a block" do
-    -> { @yieldsmixed.send(@method) }.should raise_error(ArgumentError)
+    -> { @yieldsmixed.send(@method) }.should.raise(ArgumentError)
   end
 
   describe "on a nested Lazy" do
@@ -64,7 +64,7 @@ describe :enumerator_lazy_collect_concat, shared: true do
 
       it "flattens elements when the given block returned an array or responding to .each and .force" do
         (0..Float::INFINITY).lazy.map {|n| n * 10 }.send(@method) { |n| n.to_s.chars }.first(6).should == %w[0 1 0 2 0 3]
-        (0..Float::INFINITY).lazy.map {|n| n * 10 }.send(@method) { |n| n.to_s.each_char }.first(6).all? { |o| o.instance_of? Enumerator }.should be_true
+        (0..Float::INFINITY).lazy.map {|n| n * 10 }.send(@method) { |n| n.to_s.each_char }.first(6).all? { |o| o.instance_of? Enumerator }.should == true
         (0..Float::INFINITY).lazy.map {|n| n * 10 }.send(@method) { |n| n.to_s.each_char.lazy }.first(6).should == %w[0 1 0 2 0 3]
       end
     end
diff --git a/spec/ruby/core/enumerator/lazy/shared/select.rb b/spec/ruby/core/enumerator/lazy/shared/select.rb
index 50a00bcbf4..2d15176620 100644
--- a/spec/ruby/core/enumerator/lazy/shared/select.rb
+++ b/spec/ruby/core/enumerator/lazy/shared/select.rb
@@ -16,8 +16,8 @@ describe :enumerator_lazy_select, shared: true do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.send(@method) {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -40,7 +40,7 @@ describe :enumerator_lazy_select, shared: true do
   end
 
   it "raises an ArgumentError when not given a block" do
-    -> { @yieldsmixed.send(@method) }.should raise_error(ArgumentError)
+    -> { @yieldsmixed.send(@method) }.should.raise(ArgumentError)
   end
 
   describe "on a nested Lazy" do
diff --git a/spec/ruby/core/enumerator/lazy/shared/to_enum.rb b/spec/ruby/core/enumerator/lazy/shared/to_enum.rb
index 0c91ea55b9..75b9aefe8c 100644
--- a/spec/ruby/core/enumerator/lazy/shared/to_enum.rb
+++ b/spec/ruby/core/enumerator/lazy/shared/to_enum.rb
@@ -13,8 +13,8 @@ describe :enumerator_lazy_to_enum, shared: true do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @infinite.send @method
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@infinite)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@infinite)
   end
 
   it "sets #size to nil when not given a block" do
@@ -43,7 +43,7 @@ describe :enumerator_lazy_to_enum, shared: true do
       each_entry: [],
       each_cons: [2]
     }.each_pair do |method, args|
-      @infinite.send(method, *args).should be_an_instance_of(Enumerator::Lazy)
+      @infinite.send(method, *args).should.instance_of?(Enumerator::Lazy)
     end
   end
 
diff --git a/spec/ruby/core/enumerator/lazy/slice_after_spec.rb b/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
index 438df8d550..f8cd97178f 100644
--- a/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_after" do
     s.lazy.slice_after { |n| true }.first(100).should ==
       s.first(100).slice_after { |n| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_after { |n| true }.should.is_a?(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/slice_before_spec.rb b/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
index 6c8660c1a1..192e853343 100644
--- a/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_before" do
     s.lazy.slice_before { |n| true }.first(100).should ==
       s.first(100).slice_before { |n| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_before { |n| true }.should.is_a?(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/slice_when_spec.rb b/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
index e7673def47..fc9d5f5069 100644
--- a/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_when" do
     s.lazy.slice_when { |a, b| true }.first(100).should ==
       s.first(100).slice_when { |a, b| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_when { |a, b| true }.should.is_a?(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/take_spec.rb b/spec/ruby/core/enumerator/lazy/take_spec.rb
index 9fc17e969f..2dd5b939e2 100644
--- a/spec/ruby/core/enumerator/lazy/take_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/take_spec.rb
@@ -2,8 +2,16 @@
 
 require_relative '../../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../enumerable/shared/value_packing'
 
 describe "Enumerator::Lazy#take" do
+  describe "value packing of source yields (matches Enumerable#take)" do
+    before :each do
+      @take = -> e { e.lazy.take(1) }
+    end
+    it_behaves_like :enumerable_value_packing, nil
+  end
+
   before :each do
     @yieldsmixed = EnumeratorLazySpecs::YieldsMixed.new.to_enum.lazy
     @eventsmixed = EnumeratorLazySpecs::EventsMixed.new.to_enum.lazy
@@ -16,8 +24,8 @@ describe "Enumerator::Lazy#take" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.take(1)
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets given count to size if the given count is less than old size" do
diff --git a/spec/ruby/core/enumerator/lazy/take_while_spec.rb b/spec/ruby/core/enumerator/lazy/take_while_spec.rb
index bcea0b1419..c369712c56 100644
--- a/spec/ruby/core/enumerator/lazy/take_while_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/take_while_spec.rb
@@ -16,8 +16,8 @@ describe "Enumerator::Lazy#take_while" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.take_while {}
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "sets #size to nil" do
@@ -40,7 +40,7 @@ describe "Enumerator::Lazy#take_while" do
   end
 
   it "raises an ArgumentError when not given a block" do
-    -> { @yieldsmixed.take_while }.should raise_error(ArgumentError)
+    -> { @yieldsmixed.take_while }.should.raise(ArgumentError)
   end
 
   describe "on a nested Lazy" do
diff --git a/spec/ruby/core/enumerator/lazy/uniq_spec.rb b/spec/ruby/core/enumerator/lazy/uniq_spec.rb
index ce67ace5ab..d30ed8df2f 100644
--- a/spec/ruby/core/enumerator/lazy/uniq_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/uniq_spec.rb
@@ -8,7 +8,7 @@ describe 'Enumerator::Lazy#uniq' do
     end
 
     it 'returns a lazy enumerator' do
-      @lazy.should be_an_instance_of(Enumerator::Lazy)
+      @lazy.should.instance_of?(Enumerator::Lazy)
       @lazy.force.should == [0, 1]
     end
 
@@ -28,7 +28,7 @@ describe 'Enumerator::Lazy#uniq' do
     end
 
     it 'returns a lazy enumerator' do
-      @lazy.should be_an_instance_of(Enumerator::Lazy)
+      @lazy.should.instance_of?(Enumerator::Lazy)
       @lazy.force.should == [0, 1]
     end
 
diff --git a/spec/ruby/core/enumerator/lazy/with_index_spec.rb b/spec/ruby/core/enumerator/lazy/with_index_spec.rb
new file mode 100644
index 0000000000..2e983fd3b1
--- /dev/null
+++ b/spec/ruby/core/enumerator/lazy/with_index_spec.rb
@@ -0,0 +1,36 @@
+# -*- encoding: us-ascii -*-
+
+require_relative '../../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Enumerator::Lazy#with_index" do
+  it "enumerates with an index" do
+    (0..Float::INFINITY).lazy.with_index.map { |i, idx| [i, idx] }.first(3).should == [[0, 0], [1, 1], [2, 2]]
+  end
+
+  it "enumerates with an index starting at a given offset" do
+    (0..Float::INFINITY).lazy.with_index(3).map { |i, idx| [i, idx] }.first(3).should == [[0, 3], [1, 4], [2, 5]]
+  end
+
+  it "enumerates with an index starting at 0 when offset is nil" do
+    (0..Float::INFINITY).lazy.with_index(nil).map { |i, idx| [i, idx] }.first(3).should == [[0, 0], [1, 1], [2, 2]]
+  end
+
+  it "raises TypeError when offset does not convert to Integer" do
+    -> { (0..Float::INFINITY).lazy.with_index(false).map { |i, idx| i }.first(3) }.should.raise(TypeError)
+  end
+
+  it "enumerates with a given block" do
+    result = []
+    (0..Float::INFINITY).lazy.with_index { |i, idx| result << [i * 2, idx] }.first(3)
+    result.should == [[0,0],[2,1],[4,2]]
+  end
+
+  it "resets after a new call to each" do
+    enum = (0..2).lazy.with_index.map { |i, idx| [i, idx] }
+    result = []
+    enum.each { |i, idx| result << [i, idx] }
+    enum.each { |i, idx| result << [i, idx] }
+    result.should == [[0,0], [1,1], [2,2], [0,0], [1,1], [2,2]]
+  end
+end
diff --git a/spec/ruby/core/enumerator/lazy/zip_spec.rb b/spec/ruby/core/enumerator/lazy/zip_spec.rb
index 5a828c1dcc..9f612542d7 100644
--- a/spec/ruby/core/enumerator/lazy/zip_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/zip_spec.rb
@@ -16,8 +16,8 @@ describe "Enumerator::Lazy#zip" do
 
   it "returns a new instance of Enumerator::Lazy" do
     ret = @yieldsmixed.zip []
-    ret.should be_an_instance_of(Enumerator::Lazy)
-    ret.should_not equal(@yieldsmixed)
+    ret.should.instance_of?(Enumerator::Lazy)
+    ret.should_not.equal?(@yieldsmixed)
   end
 
   it "keeps size" do
@@ -40,11 +40,11 @@ describe "Enumerator::Lazy#zip" do
   end
 
   it "returns a Lazy when no arguments given" do
-    @yieldsmixed.zip.should be_an_instance_of(Enumerator::Lazy)
+    @yieldsmixed.zip.should.instance_of?(Enumerator::Lazy)
   end
 
   it "raises a TypeError if arguments contain non-list object" do
-    -> { @yieldsmixed.zip [], Object.new, [] }.should raise_error(TypeError)
+    -> { @yieldsmixed.zip [], Object.new, [] }.should.raise(TypeError)
   end
 
   describe "on a nested Lazy" do
diff --git a/spec/ruby/core/enumerator/new_spec.rb b/spec/ruby/core/enumerator/new_spec.rb
index 170809dbc1..eb6c13759e 100644
--- a/spec/ruby/core/enumerator/new_spec.rb
+++ b/spec/ruby/core/enumerator/new_spec.rb
@@ -1,41 +1,115 @@
 require_relative '../../spec_helper'
 
 describe "Enumerator.new" do
-  it "creates a new custom enumerator with the given object, iterator and arguments" do
-    enum = Enumerator.new(1, :upto, 3)
-    enum.should be_an_instance_of(Enumerator)
+  context "no block given" do
+    it "raises" do
+      -> { Enumerator.new(1, :upto, 3) }.should.raise(ArgumentError)
+    end
   end
 
-  it "creates a new custom enumerator that responds to #each" do
-    enum = Enumerator.new(1, :upto, 3)
-    enum.respond_to?(:each).should == true
-  end
+  context "when passed a block" do
+    it "defines iteration with block, yielder argument and calling << method" do
+      enum = Enumerator.new do |yielder|
+        a = 1
 
-  it "creates a new custom enumerator that runs correctly" do
-    Enumerator.new(1, :upto, 3).map{|x|x}.should == [1,2,3]
-  end
+        loop do
+          yielder << a
+          a = a + 1
+        end
+      end
 
-  it "aliases the second argument to :each" do
-    Enumerator.new(1..2).to_a.should == Enumerator.new(1..2, :each).to_a
-  end
+      enum.take(3).should == [1, 2, 3]
+    end
 
-  it "doesn't check for the presence of the iterator method" do
-    Enumerator.new(nil).should be_an_instance_of(Enumerator)
-  end
+    it "defines iteration with block, yielder argument and calling yield method" do
+      enum = Enumerator.new do |yielder|
+        a = 1
+
+        loop do
+          yielder.yield(a)
+          a = a + 1
+        end
+      end
+
+      enum.take(3).should == [1, 2, 3]
+    end
+
+    it "defines iteration with block, yielder argument and treating it as a proc" do
+      enum = Enumerator.new do |yielder|
+        "a\nb\nc".each_line(&yielder)
+      end
+
+      enum.to_a.should == ["a\n", "b\n", "c"]
+    end
+
+    describe '#yield' do
+      it 'accepts a single argument' do
+        Enumerator.new { |y| y.yield(1) }.to_a.should == [1]
+        Enumerator.new { |y| y.yield(1) }.first.should == 1
+      end
+
+      it 'accepts multiple arguments' do
+        Enumerator.new { |y| y.yield(1, 2) }.to_a.should == [[1, 2]]
+        Enumerator.new { |y| y.yield(1, 2) }.first.should == [1, 2]
+      end
+
+      it "doesn't double-wrap arrays" do
+        Enumerator.new { |y| y.yield([1]) }.to_a.should == [[1]]
+        Enumerator.new { |y| y.yield([1]) }.first.should == [1]
+
+        Enumerator.new { |y| y.yield([1, 2]) }.to_a.should == [[1, 2]]
+        Enumerator.new { |y| y.yield([1, 2]) }.first.should == [1, 2]
+      end
+
+      it 'returns nil' do
+        ScratchPad.record []
+        Enumerator.new do |y|
+          ScratchPad << y.yield(1)
+        end.to_a
 
-  it "uses the latest define iterator method" do
-    class StrangeEach
-      def each
-        yield :foo
+        ScratchPad.recorded.should == [nil]
+      end
+
+      it 'accepts keyword arguments and treats them as a positional hash' do
+        Enumerator.new { |y| y.yield(foo: 42) }.to_a.should == [{ foo: 42 }]
+        Enumerator.new { |y| y.yield(foo: 42) }.first.should == { foo: 42 }
+
+        Enumerator.new { |y| y.yield(123, foo: 42) }.to_a.should == [[123, { foo: 42 }]]
+        Enumerator.new { |y| y.yield(123, foo: 42) }.first.should == [123, { foo: 42 }]
       end
     end
-    enum = Enumerator.new(StrangeEach.new)
-    enum.to_a.should == [:foo]
-    class StrangeEach
-      def each
-        yield :bar
+
+    describe '#<<' do
+      it 'accepts a single argument' do
+        Enumerator.new { |y| y.<<(1) }.to_a.should == [1]
+        Enumerator.new { |y| y.<<(1) }.first.should == 1
+      end
+
+      it "doesn't double-wrap arrays" do
+        Enumerator.new { |y| y.<<([1]) }.to_a.should == [[1]]
+        Enumerator.new { |y| y.<<([1]) }.first.should == [1]
+
+        Enumerator.new { |y| y.<<([1, 2]) }.to_a.should == [[1, 2]]
+        Enumerator.new { |y| y.<<([1, 2]) }.first.should == [1, 2]
+      end
+
+      it 'accepts keyword arguments and treats them as a positional hash' do
+        Enumerator.new { |y| y.<<(foo: 42) }.to_a.should == [{ foo: 42 }]
+        Enumerator.new { |y| y.<<(foo: 42) }.first.should == { foo: 42 }
+      end
+
+      it 'can be chained' do
+        enum = Enumerator.new do |y|
+          y << 1 << 2
+        end
+        enum.to_a.should == [1, 2]
+      end
+
+      it 'raises ArgumentError when given more than one argument' do
+        -> {
+          Enumerator.new { |y| y.<<(1, 2) }.to_a
+        }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 1)")
       end
     end
-    enum.to_a.should == [:bar]
   end
 end
diff --git a/spec/ruby/core/enumerator/next_spec.rb b/spec/ruby/core/enumerator/next_spec.rb
index 3e9ed8b015..77e79185a9 100644
--- a/spec/ruby/core/enumerator/next_spec.rb
+++ b/spec/ruby/core/enumerator/next_spec.rb
@@ -13,15 +13,26 @@ describe "Enumerator#next" do
 
   it "raises a StopIteration exception at the end of the stream" do
     3.times { @enum.next }
-    -> { @enum.next }.should raise_error(StopIteration)
+    -> { @enum.next }.should.raise(StopIteration)
   end
 
   it "cannot be called again until the enumerator is rewound" do
     3.times { @enum.next }
-    -> { @enum.next }.should raise_error(StopIteration)
-    -> { @enum.next }.should raise_error(StopIteration)
-    -> { @enum.next }.should raise_error(StopIteration)
+    -> { @enum.next }.should.raise(StopIteration)
+    -> { @enum.next }.should.raise(StopIteration)
+    -> { @enum.next }.should.raise(StopIteration)
     @enum.rewind
     @enum.next.should == 1
   end
+
+  it "restarts the enumerator if an exception terminated a previous iteration" do
+    exception = StandardError.new
+    enum = Enumerator.new do
+      raise exception
+    end
+
+    result = 2.times.map { enum.next rescue $! }
+
+    result.should == [exception, exception]
+  end
 end
diff --git a/spec/ruby/core/enumerator/next_values_spec.rb b/spec/ruby/core/enumerator/next_values_spec.rb
index 201b5d323f..63e024e2b4 100644
--- a/spec/ruby/core/enumerator/next_values_spec.rb
+++ b/spec/ruby/core/enumerator/next_values_spec.rb
@@ -11,6 +11,7 @@ describe "Enumerator#next_values" do
       yield :e1, :e2, :e3
       yield nil
       yield
+      yield [:f1, :f2]
     end
 
     @e = o.to_enum
@@ -48,8 +49,13 @@ describe "Enumerator#next_values" do
     @e.next_values.should == []
   end
 
-  it "raises StopIteration if called on a finished enumerator" do
+  it "returns an array of array if yield is called with an array" do
     7.times { @e.next }
-    -> { @e.next_values }.should raise_error(StopIteration)
+    @e.next_values.should == [[:f1, :f2]]
+  end
+
+  it "raises StopIteration if called on a finished enumerator" do
+    8.times { @e.next }
+    -> { @e.next_values }.should.raise(StopIteration)
   end
 end
diff --git a/spec/ruby/core/enumerator/peek_spec.rb b/spec/ruby/core/enumerator/peek_spec.rb
index 2334385437..096fd2b10c 100644
--- a/spec/ruby/core/enumerator/peek_spec.rb
+++ b/spec/ruby/core/enumerator/peek_spec.rb
@@ -31,6 +31,6 @@ describe "Enumerator#peek" do
 
   it "raises StopIteration if called on a finished enumerator" do
     5.times { @e.next }
-    -> { @e.peek }.should raise_error(StopIteration)
+    -> { @e.peek }.should.raise(StopIteration)
   end
 end
diff --git a/spec/ruby/core/enumerator/peek_values_spec.rb b/spec/ruby/core/enumerator/peek_values_spec.rb
index 7865546515..63f7988bcd 100644
--- a/spec/ruby/core/enumerator/peek_values_spec.rb
+++ b/spec/ruby/core/enumerator/peek_values_spec.rb
@@ -11,6 +11,7 @@ describe "Enumerator#peek_values" do
       yield :e1, :e2, :e3
       yield nil
       yield
+      yield [:f1, :f2]
     end
 
     @e = o.to_enum
@@ -50,8 +51,13 @@ describe "Enumerator#peek_values" do
     @e.peek_values.should == []
   end
 
-  it "raises StopIteration if called on a finished enumerator" do
+  it "returns an array of array if yield is called with an array" do
     7.times { @e.next }
-    -> { @e.peek_values }.should raise_error(StopIteration)
+    @e.peek_values.should == [[:f1, :f2]]
+  end
+
+  it "raises StopIteration if called on a finished enumerator" do
+    8.times { @e.next }
+    -> { @e.peek_values }.should.raise(StopIteration)
   end
 end
diff --git a/spec/ruby/core/enumerator/plus_spec.rb b/spec/ruby/core/enumerator/plus_spec.rb
index c9bae08b04..d6c0fa93ac 100644
--- a/spec/ruby/core/enumerator/plus_spec.rb
+++ b/spec/ruby/core/enumerator/plus_spec.rb
@@ -1,35 +1,33 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator#+" do
-    before :each do
-      ScratchPad.record []
-    end
+describe "Enumerator#+" do
+  before :each do
+    ScratchPad.record []
+  end
 
-    it "returns a chain of self and provided enumerators" do
-      one   = Enumerator.new { |y| y << 1 }
-      two   = Enumerator.new { |y| y << 2 }
-      three = Enumerator.new { |y| y << 3 }
+  it "returns a chain of self and provided enumerators" do
+    one   = Enumerator.new { |y| y << 1 }
+    two   = Enumerator.new { |y| y << 2 }
+    three = Enumerator.new { |y| y << 3 }
 
-      chain = one + two + three
+    chain = one + two + three
 
-      chain.should be_an_instance_of(Enumerator::Chain)
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 2, 3]
-    end
+    chain.should.instance_of?(Enumerator::Chain)
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 2, 3]
+  end
 
-    it "calls #each on each argument" do
-      enum = Enumerator.new { |y| y << "one" }
+  it "calls #each on each argument" do
+    enum = Enumerator.new { |y| y << "one" }
 
-      obj1 = mock("obj1")
-      obj1.should_receive(:each).once.and_yield("two")
+    obj1 = mock("obj1")
+    obj1.should_receive(:each).once.and_yield("two")
 
-      obj2 = mock("obj2")
-      obj2.should_receive(:each).once.and_yield("three")
+    obj2 = mock("obj2")
+    obj2.should_receive(:each).once.and_yield("three")
 
-      chain = enum + obj1 + obj2
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == ["one", "two", "three"]
-    end
+    chain = enum + obj1 + obj2
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == ["one", "two", "three"]
   end
 end
diff --git a/spec/ruby/core/enumerator/produce_spec.rb b/spec/ruby/core/enumerator/produce_spec.rb
new file mode 100644
index 0000000000..eb1b09294e
--- /dev/null
+++ b/spec/ruby/core/enumerator/produce_spec.rb
@@ -0,0 +1,78 @@
+require_relative '../../spec_helper'
+
+describe "Enumerator.produce" do
+  it "creates an infinite enumerator" do
+    enum = Enumerator.produce(0) { |prev| prev + 1 }
+
+    enum.size.should == Float::INFINITY
+    enum.take(5).should == [0, 1, 2, 3, 4]
+  end
+
+  it "terminates iteration when block raises StopIteration exception" do
+    enum = Enumerator.produce(0) do | prev|
+      raise StopIteration if prev >= 2
+      prev + 1
+    end
+
+    enum.to_a.should == [0, 1, 2]
+  end
+
+  context "when initial value skipped" do
+    it "uses nil instead" do
+      ScratchPad.record []
+      enum = Enumerator.produce { |prev| ScratchPad << prev; (prev || 0) + 1 }
+
+      enum.take(3).should == [1, 2, 3]
+      ScratchPad.recorded.should == [nil, 1, 2]
+    end
+
+    it "starts enumerable from result of first block call" do
+      array = "a\nb\nc\nd".lines
+      lines = Enumerator.produce { array.shift }.take_while { |s| s }
+
+      lines.should == ["a\n", "b\n", "c\n", "d"]
+    end
+  end
+
+  it "raises ArgumentError when no block is given" do
+    -> { Enumerator.produce }.should.raise(ArgumentError, "no block given")
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "accepts keyword arguments as the initial value" do
+      enum = Enumerator.produce(a: 1, b: 1) {}
+      enum.take(1).should == [{a: 1, b: 1}]
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "raises ArgumentError for unknown keyword arguments" do
+      -> { Enumerator.produce(a: 1, b: 1) {} }.should.raise(ArgumentError, /unknown keywords/)
+    end
+  end
+
+  ruby_version_is "4.0" do
+    context "with size keyword argument" do
+      it "sets the size of the enumerator" do
+        enum = Enumerator.produce(0, size: 10) { |n| n + 1 }
+
+        enum.size.should == 10
+        enum.take(5).should == [0, 1, 2, 3, 4]
+      end
+
+      it "accepts a callable" do
+        enum = Enumerator.produce(0, size: -> { 5 * 5 }) { |n| n + 1 }
+
+        enum.size.should == 25
+        enum.take(5).should == [0, 1, 2, 3, 4]
+      end
+
+      it "accepts nil" do
+        enum = Enumerator.produce(0, size: nil) { |n| n + 1 }
+
+        enum.size.should == nil
+        enum.take(5).should == [0, 1, 2, 3, 4]
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/each_spec.rb b/spec/ruby/core/enumerator/product/each_spec.rb
new file mode 100644
index 0000000000..a5dced4db1
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/each_spec.rb
@@ -0,0 +1,85 @@
+require_relative '../../../spec_helper'
+require_relative '../../enumerable/shared/enumeratorized'
+
+describe "Enumerator::Product#each" do
+  it_behaves_like :enumeratorized_with_origin_size, :each, Enumerator::Product.new([1, 2], [:a, :b])
+
+  it "yields each element of Cartesian product of enumerators" do
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+    acc = []
+    enum.each { |e| acc << e }
+    acc.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "calls #each_entry method on enumerators" do
+    object1 = Object.new
+    def object1.each_entry
+      yield 1
+      yield 2
+    end
+
+    object2 = Object.new
+    def object2.each_entry
+      yield :a
+      yield :b
+    end
+
+    enum = Enumerator::Product.new(object1, object2)
+    acc = []
+    enum.each { |e| acc << e }
+    acc.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "raises a NoMethodError if the object doesn't respond to #each_entry" do
+    -> {
+      Enumerator::Product.new(Object.new).each {}
+    }.should.raise(NoMethodError, /undefined method [`']each_entry' for/)
+  end
+
+  it "returns enumerator if not given a block" do
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+    enum.each.should.kind_of?(Enumerator)
+
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+    enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "returns self if given a block" do
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+    enum.each {}.should.equal?(enum)
+  end
+
+  it "doesn't accept arguments" do
+    Enumerator::Product.instance_method(:each).arity.should == 0
+  end
+
+  it "yields each element to a block that takes multiple arguments" do
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+
+    acc = []
+    enum.each { |x, y| acc << x }
+    acc.should == [1, 1, 2, 2]
+
+    acc = []
+    enum.each { |x, y| acc << y }
+    acc.should == [:a, :b, :a, :b]
+
+    acc = []
+    enum.each { |x, y, z| acc << z }
+    acc.should == [nil, nil, nil, nil]
+  end
+
+  it "yields no element when any enumerable is empty" do
+    enum = Enumerator::Product.new([], [1])
+
+    acc = []
+    enum.each { |x| acc << x }
+    acc.should == []
+
+    enum = Enumerator::Product.new([1], [])
+
+    acc = []
+    enum.each { |x| acc << x }
+    acc.should == []
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/initialize_copy_spec.rb b/spec/ruby/core/enumerator/product/initialize_copy_spec.rb
new file mode 100644
index 0000000000..b5d2b345a9
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/initialize_copy_spec.rb
@@ -0,0 +1,52 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Product#initialize_copy" do
+  it "replaces content of the receiver with content of the other object" do
+    enum = Enumerator::Product.new([true, false])
+    enum2 = Enumerator::Product.new([1, 2], [:a, :b])
+
+    enum.send(:initialize_copy, enum2)
+    enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "returns self" do
+    enum = Enumerator::Product.new([true, false])
+    enum2 = Enumerator::Product.new([1, 2], [:a, :b])
+
+    enum.send(:initialize_copy, enum2).should.equal?(enum)
+  end
+
+  it "is a private method" do
+    Enumerator::Product.private_instance_methods(false).should.include?(:initialize_copy)
+  end
+
+  it "does nothing if the argument is the same as the receiver" do
+    enum = Enumerator::Product.new(1..2)
+    enum.send(:initialize_copy, enum).should.equal?(enum)
+
+    enum.freeze
+    enum.send(:initialize_copy, enum).should.equal?(enum)
+  end
+
+  it "raises FrozenError if the receiver is frozen" do
+    enum = Enumerator::Product.new(1..2)
+    enum2 = Enumerator::Product.new(3..4)
+
+    -> { enum.freeze.send(:initialize_copy, enum2) }.should.raise(FrozenError)
+  end
+
+  it "raises TypeError if the objects are of different class" do
+    enum = Enumerator::Product.new(1..2)
+    enum2 = Class.new(Enumerator::Product).new(3..4)
+
+    -> { enum.send(:initialize_copy, enum2) }.should.raise(TypeError, 'initialize_copy should take same class object')
+    -> { enum2.send(:initialize_copy, enum) }.should.raise(TypeError, 'initialize_copy should take same class object')
+  end
+
+  it "raises ArgumentError if the argument is not initialized yet" do
+    enum = Enumerator::Product.new(1..2)
+    enum2 = Enumerator::Product.allocate
+
+    -> { enum.send(:initialize_copy, enum2) }.should.raise(ArgumentError, 'uninitialized product')
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/initialize_spec.rb b/spec/ruby/core/enumerator/product/initialize_spec.rb
new file mode 100644
index 0000000000..8814f9d3c7
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/initialize_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Product#initialize" do
+  before :each do
+    @uninitialized = Enumerator::Product.allocate
+  end
+
+  it "is a private method" do
+    Enumerator::Product.private_instance_methods(false).should.include?(:initialize)
+  end
+
+  it "returns self" do
+    @uninitialized.send(:initialize).should.equal?(@uninitialized)
+  end
+
+  it "accepts many arguments" do
+    @uninitialized.send(:initialize, 0..1, 2..3, 4..5).should.equal?(@uninitialized)
+  end
+
+  it "accepts arguments that are not Enumerable nor responding to :each_entry" do
+    @uninitialized.send(:initialize, Object.new).should.equal?(@uninitialized)
+  end
+
+  describe "on frozen instance" do
+    it "raises a FrozenError" do
+      -> {
+        @uninitialized.freeze.send(:initialize, 0..1)
+      }.should.raise(FrozenError)
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/inspect_spec.rb b/spec/ruby/core/enumerator/product/inspect_spec.rb
new file mode 100644
index 0000000000..e0d7441f26
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/inspect_spec.rb
@@ -0,0 +1,20 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Product#inspect" do
+  it "returns a String including enumerators" do
+    enum = Enumerator::Product.new([1, 2], [:a, :b])
+    enum.inspect.should == "#<Enumerator::Product: [[1, 2], [:a, :b]]>"
+  end
+
+  it "represents a recursive element with '[...]'" do
+    enum = [1, 2]
+    enum_recursive = Enumerator::Product.new(enum)
+
+    enum << enum_recursive
+    enum_recursive.inspect.should == "#<Enumerator::Product: [[1, 2, #<Enumerator::Product: ...>]]>"
+  end
+
+  it "returns a not initialized representation if #initialized is not called yet" do
+    Enumerator::Product.allocate.inspect.should == "#<Enumerator::Product: uninitialized>"
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/rewind_spec.rb b/spec/ruby/core/enumerator/product/rewind_spec.rb
new file mode 100644
index 0000000000..2beffaf5c1
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/rewind_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Product#rewind" do
+  before :each do
+    @enum = Enumerator::Product.new([1, 2].each.to_enum, [:a, :b].each.to_enum)
+  end
+
+  it "resets the enumerator to its initial state" do
+    @enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+    @enum.rewind
+    @enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "returns self" do
+    @enum.rewind.should.equal? @enum
+  end
+
+  it "has no effect on a new enumerator" do
+    @enum.rewind
+    @enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "has no effect if called multiple, consecutive times" do
+    @enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+    @enum.rewind
+    @enum.rewind
+    @enum.each.to_a.should == [[1, :a], [1, :b], [2, :a], [2, :b]]
+  end
+
+  it "calls the enclosed object's rewind method if one exists" do
+    obj = mock('rewinder')
+    enum = Enumerator::Product.new(obj.to_enum)
+
+    obj.should_receive(:rewind)
+    enum.rewind
+  end
+
+  it "does nothing if the object doesn't have a #rewind method" do
+    obj = mock('rewinder')
+    enum = Enumerator::Product.new(obj.to_enum)
+
+    enum.rewind.should == enum
+  end
+
+  it "calls a rewind method on each enumerable in direct order" do
+    ScratchPad.record []
+
+    object1 = Object.new
+    def object1.rewind; ScratchPad << :object1; end
+
+    object2 = Object.new
+    def object2.rewind; ScratchPad << :object2; end
+
+    object3 = Object.new
+    def object3.rewind; ScratchPad << :object3; end
+
+    enum = Enumerator::Product.new(object1, object2, object3)
+    enum.rewind
+
+    ScratchPad.recorded.should == [:object1, :object2, :object3]
+  end
+end
diff --git a/spec/ruby/core/enumerator/product/size_spec.rb b/spec/ruby/core/enumerator/product/size_spec.rb
new file mode 100644
index 0000000000..0ba427af9a
--- /dev/null
+++ b/spec/ruby/core/enumerator/product/size_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerator::Product#size" do
+  it "returns the total size of the enumerator product calculated by multiplying the sizes of enumerables in the product" do
+    product = Enumerator::Product.new(1..2, 1..3, 1..4)
+    product.size.should == 24 # 2 * 3 * 4
+  end
+
+  it "returns nil if any enumerable reports its size as nil" do
+    enum = Object.new
+    def enum.size; nil; end
+
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == nil
+  end
+
+  it "returns Float::INFINITY if any enumerable reports its size as Float::INFINITY" do
+    enum = Object.new
+    def enum.size; Float::INFINITY; end
+
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == Float::INFINITY
+  end
+
+  it "returns nil if any enumerable reports its size as Float::NAN" do
+    enum = Object.new
+    def enum.size; Float::NAN; end
+
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == nil
+  end
+
+  it "returns nil if any enumerable doesn't respond to #size" do
+    enum = Object.new
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == nil
+  end
+
+  it "returns nil if any enumerable reports a not-convertible to Integer" do
+    enum = Object.new
+    def enum.size; :symbol; end
+
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == nil
+  end
+
+  it "returns nil if any enumerable reports a non-Integer but convertible to Integer size" do
+    enum = Object.new
+    def enum.size; 1.0; end
+
+    product = Enumerator::Product.new(1..2, enum)
+    product.size.should == nil
+  end
+
+  ruby_version_is "3.4" do
+    it "returns zero when any enumerable reports zero" do
+      enum = Enumerator::Product.new(1...1, ["A", "B"])
+      enum.size.should == 0
+
+      enum = Enumerator::Product.new(["A", "B"], 1...1)
+      enum.size.should == 0
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/product_spec.rb b/spec/ruby/core/enumerator/product_spec.rb
new file mode 100644
index 0000000000..0f37ef76e7
--- /dev/null
+++ b/spec/ruby/core/enumerator/product_spec.rb
@@ -0,0 +1,91 @@
+require_relative '../../spec_helper'
+
+describe "Enumerator.product" do
+  it "returns a Cartesian product of enumerators" do
+    enum = Enumerator.product(1..2, ["A", "B"])
+    enum.to_a.should == [[1, "A"], [1, "B"], [2, "A"], [2, "B"]]
+  end
+
+  it "accepts a list of enumerators of any length" do
+    enum = Enumerator.product(1..2)
+    enum.to_a.should == [[1], [2]]
+
+    enum = Enumerator.product(1..2, ["A"])
+    enum.to_a.should == [[1, "A"], [2, "A"]]
+
+    enum = Enumerator.product(1..2, ["A"], ["B"])
+    enum.to_a.should == [[1, "A", "B"], [2, "A", "B"]]
+
+    enum = Enumerator.product(2..3, ["A"], ["B"], ["C"])
+    enum.to_a.should == [[2, "A", "B", "C"], [3, "A", "B", "C"]]
+  end
+
+  it "returns an enumerator with an empty array when no arguments passed" do
+    enum = Enumerator.product
+    enum.to_a.should == [[]]
+  end
+
+  it "returns an instance of Enumerator::Product" do
+    enum = Enumerator.product
+    enum.class.should == Enumerator::Product
+  end
+
+  it "accepts infinite enumerators and returns infinite enumerator" do
+    enum = Enumerator.product(1.., ["A", "B"])
+    enum.take(5).should == [[1, "A"], [1, "B"], [2, "A"], [2, "B"], [3, "A"]]
+    enum.size.should == Float::INFINITY
+  end
+
+  it "accepts a block" do
+    elems = []
+    enum = Enumerator.product(1..2, ["X", "Y"]) { elems << _1 }
+
+    elems.should == [[1, "X"], [1, "Y"], [2, "X"], [2, "Y"]]
+  end
+
+  it "returns nil when a block passed" do
+    Enumerator.product(1..2) {}.should == nil
+  end
+
+  # https://bugs.ruby-lang.org/issues/19829
+  it "reject keyword arguments" do
+    -> {
+      Enumerator.product(1..3, foo: 1, bar: 2)
+    }.should.raise(ArgumentError, "unknown keywords: :foo, :bar")
+  end
+
+  it "calls only #each_entry method on arguments" do
+    object = Object.new
+    def object.each_entry
+      yield 1
+      yield 2
+    end
+
+    enum = Enumerator.product(object, ["A", "B"])
+    enum.to_a.should == [[1, "A"], [1, "B"], [2, "A"], [2, "B"]]
+  end
+
+  it "raises NoMethodError when argument doesn't respond to #each_entry" do
+    -> {
+      Enumerator.product(Object.new).to_a
+    }.should.raise(NoMethodError, /undefined method [`']each_entry' for/)
+  end
+
+  it "calls #each_entry lazily" do
+    Enumerator.product(Object.new).should.is_a?(Enumerator)
+  end
+
+  it "iterates through consuming enumerator elements only once" do
+    a = [1, 2, 3]
+    i = 0
+
+    enum = Enumerator.new do |y|
+      while i < a.size
+        y << a[i]
+        i += 1
+      end
+    end
+
+    Enumerator.product(['a', 'b'], enum).to_a.should == [["a", 1], ["a", 2], ["a", 3]]
+  end
+end
diff --git a/spec/ruby/core/enumerator/rewind_spec.rb b/spec/ruby/core/enumerator/rewind_spec.rb
index a105f2c619..6ba0edf174 100644
--- a/spec/ruby/core/enumerator/rewind_spec.rb
+++ b/spec/ruby/core/enumerator/rewind_spec.rb
@@ -14,7 +14,7 @@ describe "Enumerator#rewind" do
   end
 
   it "returns self" do
-    @enum.rewind.should == @enum
+    @enum.rewind.should.equal? @enum
   end
 
   it "has no effect on a new enumerator" do
@@ -49,7 +49,7 @@ describe "Enumerator#rewind" do
     obj = mock('rewinder')
     enum = obj.to_enum
     obj.should_receive(:each).at_most(1)
-    -> { enum.rewind.should == enum }.should_not raise_error
+    enum.rewind.should == enum
   end
 end
 
diff --git a/spec/ruby/core/enumerator/shared/enum_for.rb b/spec/ruby/core/enumerator/shared/enum_for.rb
new file mode 100644
index 0000000000..4388103ecf
--- /dev/null
+++ b/spec/ruby/core/enumerator/shared/enum_for.rb
@@ -0,0 +1,57 @@
+describe :enum_for, shared: true do
+  it "is defined in Kernel" do
+    Kernel.method_defined?(@method).should == true
+  end
+
+  it "returns a new enumerator" do
+    "abc".send(@method).should.instance_of?(Enumerator)
+  end
+
+  it "defaults the first argument to :each" do
+    enum = [1,2].send(@method)
+    enum.map { |v| v }.should == [1,2].each { |v| v }
+  end
+
+  it "sets regexp matches in the caller" do
+    "wawa".send(@method, :scan, /./).map {|o| $& }.should == ["w", "a", "w", "a"]
+    a = []
+    "wawa".send(@method, :scan, /./).each {|o| a << $& }
+    a.should == ["w", "a", "w", "a"]
+  end
+
+  it "exposes multi-arg yields as an array" do
+    o = Object.new
+    def o.each
+      yield :a
+      yield :b1, :b2
+      yield [:c]
+      yield :d1, :d2
+      yield :e1, :e2, :e3
+    end
+
+    enum = o.send(@method)
+    enum.next.should == :a
+    enum.next.should == [:b1, :b2]
+    enum.next.should == [:c]
+    enum.next.should == [:d1, :d2]
+    enum.next.should == [:e1, :e2, :e3]
+  end
+
+  it "uses the passed block's value to calculate the size of the enumerator" do
+    Object.new.enum_for { 100 }.size.should == 100
+  end
+
+  it "defers the evaluation of the passed block until #size is called" do
+    ScratchPad.record []
+
+    enum = Object.new.enum_for do
+      ScratchPad << :called
+      100
+    end
+
+    ScratchPad.recorded.should.empty?
+
+    enum.size
+    ScratchPad.recorded.should == [:called]
+  end
+end
diff --git a/spec/ruby/core/enumerator/shared/with_index.rb b/spec/ruby/core/enumerator/shared/with_index.rb
new file mode 100644
index 0000000000..0992397e95
--- /dev/null
+++ b/spec/ruby/core/enumerator/shared/with_index.rb
@@ -0,0 +1,33 @@
+require_relative '../../../spec_helper'
+
+describe :enum_with_index, shared: true do
+
+  require_relative '../fixtures/classes'
+
+  before :each do
+    @origin = [1, 2, 3, 4]
+    @enum = @origin.to_enum
+  end
+
+  it "passes each element and its index to block" do
+    a = []
+    @enum.send(@method) { |o, i| a << [o, i] }
+    a.should == [[1, 0], [2, 1], [3, 2], [4, 3]]
+  end
+
+  it "returns the object being enumerated when given a block" do
+    @enum.send(@method) { |o, i| :glark }.should.equal?(@origin)
+  end
+
+  it "binds splat arguments properly" do
+    acc = []
+    @enum.send(@method) { |*b| c,d = b; acc << c; acc << d }
+    [1, 0, 2, 1, 3, 2, 4, 3].should == acc
+  end
+
+  it "returns an enumerator if no block is supplied" do
+    ewi = @enum.send(@method)
+    ewi.should.instance_of?(Enumerator)
+    ewi.to_a.should == [[1, 0], [2, 1], [3, 2], [4, 3]]
+  end
+end
diff --git a/spec/ruby/core/enumerator/shared/with_object.rb b/spec/ruby/core/enumerator/shared/with_object.rb
new file mode 100644
index 0000000000..50d4f24eb3
--- /dev/null
+++ b/spec/ruby/core/enumerator/shared/with_object.rb
@@ -0,0 +1,42 @@
+require_relative '../../../spec_helper'
+
+describe :enum_with_object, shared: true do
+  before :each do
+    @enum = [:a, :b].to_enum
+    @memo = ''
+    @block_params = @enum.send(@method, @memo).to_a
+  end
+
+  it "receives an argument" do
+    @enum.method(@method).arity.should == 1
+  end
+
+  context "with block" do
+    it "returns the given object" do
+      ret = @enum.send(@method, @memo) do |elm, memo|
+        # nothing
+      end
+      ret.should.equal?(@memo)
+    end
+
+    context "the block parameter" do
+      it "passes each element to first parameter" do
+        @block_params[0][0].should.equal?(:a)
+        @block_params[1][0].should.equal?(:b)
+      end
+
+      it "passes the given object to last parameter" do
+        @block_params[0][1].should.equal?(@memo)
+        @block_params[1][1].should.equal?(@memo)
+      end
+    end
+  end
+
+  context "without block" do
+    it "returns new Enumerator" do
+      ret = @enum.send(@method, @memo)
+      ret.should.instance_of?(Enumerator)
+      ret.should_not.equal?(@enum)
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/size_spec.rb b/spec/ruby/core/enumerator/size_spec.rb
index 6accd26a4e..4b2beffbbe 100644
--- a/spec/ruby/core/enumerator/size_spec.rb
+++ b/spec/ruby/core/enumerator/size_spec.rb
@@ -6,7 +6,7 @@ describe "Enumerator#size" do
   end
 
   it "returns nil if set size is nil" do
-    Enumerator.new(nil) {}.size.should be_nil
+    Enumerator.new(nil) {}.size.should == nil
   end
 
   it "returns returning value from size.call if set size is a Proc" do
diff --git a/spec/ruby/core/enumerator/to_enum_spec.rb b/spec/ruby/core/enumerator/to_enum_spec.rb
index cadfcf6314..7fb73d0c3c 100644
--- a/spec/ruby/core/enumerator/to_enum_spec.rb
+++ b/spec/ruby/core/enumerator/to_enum_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/enum_for'
+require_relative 'shared/enum_for'
 
 describe "Enumerator#to_enum" do
-  it_behaves_like :enum_for, :enum_for
+  it_behaves_like :enum_for, :to_enum
 end
diff --git a/spec/ruby/core/enumerator/with_index_spec.rb b/spec/ruby/core/enumerator/with_index_spec.rb
index ac37cee508..ca90fd18f7 100644
--- a/spec/ruby/core/enumerator/with_index_spec.rb
+++ b/spec/ruby/core/enumerator/with_index_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/with_index'
+require_relative 'shared/with_index'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Enumerator#with_index" do
@@ -9,20 +9,20 @@ describe "Enumerator#with_index" do
   it "returns a new Enumerator when no block is given" do
     enum1 = [1,2,3].select
     enum2 = enum1.with_index
-    enum2.should be_an_instance_of(Enumerator)
+    enum2.should.instance_of?(Enumerator)
     enum1.should_not === enum2
   end
 
   it "accepts an optional argument when given a block" do
     -> do
       @enum.with_index(1) { |f| f}
-    end.should_not raise_error(ArgumentError)
+    end.should_not.raise(ArgumentError)
   end
 
   it "accepts an optional argument when not given a block" do
     -> do
       @enum.with_index(1)
-    end.should_not raise_error(ArgumentError)
+    end.should_not.raise(ArgumentError)
   end
 
   it "numbers indices from the given index when given an offset but no block" do
@@ -38,7 +38,7 @@ describe "Enumerator#with_index" do
   it "raises a TypeError when the argument cannot be converted to numeric" do
     -> do
       @enum.with_index('1') {|*i| i}
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "converts non-numeric arguments to Integer via #to_int" do
@@ -69,4 +69,21 @@ describe "Enumerator#with_index" do
     @enum.with_index(-1) { |*x| res << x}
     res.should == [[1,-1], [2,0], [3,1], [4,2]]
   end
+
+  it "passes on the given block's return value" do
+    arr = [1,2,3]
+    arr.delete_if.with_index { |a,b| false }
+    arr.should == [1,2,3]
+
+    arr.delete_if.with_index { |a,b| true }
+    arr.should == []
+  end
+
+  it "returns the iterator's return value" do
+    @enum.select.with_index { |a,b| false }.should == []
+  end
+
+  it "returns the correct value if chained with itself" do
+    [:a].each.with_index.with_index.to_a.should == [[[:a,0],0]]
+  end
 end
diff --git a/spec/ruby/core/enumerator/with_object_spec.rb b/spec/ruby/core/enumerator/with_object_spec.rb
index e7ba83fd9f..58031fd765 100644
--- a/spec/ruby/core/enumerator/with_object_spec.rb
+++ b/spec/ruby/core/enumerator/with_object_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/enumerator/with_object'
+require_relative 'shared/with_object'
 
 describe "Enumerator#with_object" do
   it_behaves_like :enum_with_object, :with_object
diff --git a/spec/ruby/core/enumerator/yielder/append_spec.rb b/spec/ruby/core/enumerator/yielder/append_spec.rb
deleted file mode 100644
index dac66585a5..0000000000
--- a/spec/ruby/core/enumerator/yielder/append_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Enumerator::Yielder#<<" do
-  # TODO: There's some common behavior between yield and <<; move to a shared spec
-  it "yields the value to the block" do
-    ary = []
-    y = Enumerator::Yielder.new {|x| ary << x}
-    y << 1
-
-    ary.should == [1]
-  end
-
-  it "doesn't double-wrap Arrays" do
-    yields = []
-    y = Enumerator::Yielder.new {|args| yields << args }
-    y << [1]
-    yields.should == [[1]]
-  end
-
-  it "returns self" do
-    y = Enumerator::Yielder.new {|x| x + 1}
-    (y << 1).should equal(y)
-  end
-end
diff --git a/spec/ruby/core/enumerator/yielder/initialize_spec.rb b/spec/ruby/core/enumerator/yielder/initialize_spec.rb
deleted file mode 100644
index 5a6eee2d0f..0000000000
--- a/spec/ruby/core/enumerator/yielder/initialize_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-# -*- encoding: us-ascii -*-
-
-require_relative '../../../spec_helper'
-
-describe "Enumerator::Yielder#initialize" do
-  before :each do
-    @class = Enumerator::Yielder
-    @uninitialized = @class.allocate
-  end
-
-  it "is a private method" do
-    @class.should have_private_instance_method(:initialize, false)
-  end
-
-  it "returns self when given a block" do
-    @uninitialized.send(:initialize) {}.should equal(@uninitialized)
-  end
-end
diff --git a/spec/ruby/core/enumerator/yielder/yield_spec.rb b/spec/ruby/core/enumerator/yielder/yield_spec.rb
deleted file mode 100644
index 58fc8e007a..0000000000
--- a/spec/ruby/core/enumerator/yielder/yield_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Enumerator::Yielder#yield" do
-  it "yields the value to the block" do
-    ary = []
-    y = Enumerator::Yielder.new {|x| ary << x}
-    y.yield 1
-
-    ary.should == [1]
-  end
-
-  it "yields with passed arguments" do
-    yields = []
-    y = Enumerator::Yielder.new {|*args| yields << args }
-    y.yield 1, 2
-    yields.should == [[1, 2]]
-  end
-
-  it "returns the result of the block for the given value" do
-    y = Enumerator::Yielder.new {|x| x + 1}
-    y.yield(1).should == 2
-  end
-end
diff --git a/spec/ruby/core/env/assoc_spec.rb b/spec/ruby/core/env/assoc_spec.rb
index 853eca79a5..b81be7ddf2 100644
--- a/spec/ruby/core/env/assoc_spec.rb
+++ b/spec/ruby/core/env/assoc_spec.rb
@@ -1,8 +1,12 @@
 require_relative '../../spec_helper'
 
 describe "ENV.assoc" do
+  before :each do
+    @foo = ENV["foo"]
+  end
+
   after :each do
-    ENV.delete("foo")
+    ENV["foo"] = @foo
   end
 
   it "returns an array of the key and value of the environment variable with the given key" do
@@ -20,4 +24,8 @@ describe "ENV.assoc" do
     k.should_receive(:to_str).and_return("foo")
     ENV.assoc(k).should == ["foo", "bar"]
   end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> { ENV.assoc(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
 end
diff --git a/spec/ruby/core/env/clear_spec.rb b/spec/ruby/core/env/clear_spec.rb
index fd0984a220..c0d20193ad 100644
--- a/spec/ruby/core/env/clear_spec.rb
+++ b/spec/ruby/core/env/clear_spec.rb
@@ -4,7 +4,7 @@ describe "ENV.clear" do
   it "deletes all environment variables" do
     orig = ENV.to_hash
     begin
-      ENV.clear
+      ENV.clear.should.equal?(ENV)
 
       # This used 'env' the helper before. That shells out to 'env' which
       # itself sets up certain environment variables before it runs, because
diff --git a/spec/ruby/core/env/clone_spec.rb b/spec/ruby/core/env/clone_spec.rb
new file mode 100644
index 0000000000..bb3c7ff2f8
--- /dev/null
+++ b/spec/ruby/core/env/clone_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../spec_helper'
+
+describe "ENV#clone" do
+  it "raises ArgumentError when keyword argument 'freeze' is neither nil nor boolean" do
+    -> {
+      ENV.clone(freeze: 1)
+    }.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError when keyword argument is not 'freeze'" do
+    -> {
+      ENV.clone(foo: nil)
+    }.should.raise(ArgumentError)
+  end
+
+  it "raises TypeError" do
+    -> {
+      ENV.clone
+    }.should.raise(TypeError, /Cannot clone ENV, use ENV.to_h to get a copy of ENV as a hash/)
+  end
+end
diff --git a/spec/ruby/core/env/delete_if_spec.rb b/spec/ruby/core/env/delete_if_spec.rb
index d64443194e..4b05064eba 100644
--- a/spec/ruby/core/env/delete_if_spec.rb
+++ b/spec/ruby/core/env/delete_if_spec.rb
@@ -2,25 +2,52 @@ require_relative '../../spec_helper'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "ENV.delete_if" do
+  before :each do
+    @foo = ENV["foo"]
+    @bar = ENV["bar"]
+
+    ENV["foo"] = "0"
+    ENV["bar"] = "1"
+  end
+
+  after :each do
+    ENV["foo"] = @foo
+    ENV["bar"] = @bar
+  end
+
   it "deletes pairs if the block returns true" do
-    ENV["foo"] = "bar"
-    ENV.delete_if { |k, v| k == "foo" }
+    ENV.delete_if { |k, v| ["foo", "bar"].include?(k) }
     ENV["foo"].should == nil
+    ENV["bar"].should == nil
+  end
+
+  it "returns ENV when block given" do
+    ENV.delete_if { |k, v| ["foo", "bar"].include?(k) }.should.equal?(ENV)
   end
 
   it "returns ENV even if nothing deleted" do
-    ENV.delete_if { false }.should_not == nil
+    ENV.delete_if { false }.should.equal?(ENV)
   end
 
   it "returns an Enumerator if no block given" do
-    ENV.delete_if.should be_an_instance_of(Enumerator)
+    ENV.delete_if.should.instance_of?(Enumerator)
   end
 
   it "deletes pairs through enumerator" do
-    ENV["foo"] = "bar"
     enum = ENV.delete_if
-    enum.each { |k, v| k == "foo" }
+    enum.each { |k, v| ["foo", "bar"].include?(k) }
     ENV["foo"].should == nil
+    ENV["bar"].should == nil
+  end
+
+  it "returns ENV from enumerator" do
+    enum = ENV.delete_if
+    enum.each { |k, v| ["foo", "bar"].include?(k) }.should.equal?(ENV)
+  end
+
+  it "returns ENV from enumerator even if nothing deleted" do
+    enum = ENV.delete_if
+    enum.each { false }.should.equal?(ENV)
   end
 
   it_behaves_like :enumeratorized_with_origin_size, :delete_if, ENV
diff --git a/spec/ruby/core/env/delete_spec.rb b/spec/ruby/core/env/delete_spec.rb
index 1e677fb252..db6d07b057 100644
--- a/spec/ruby/core/env/delete_spec.rb
+++ b/spec/ruby/core/env/delete_spec.rb
@@ -1,8 +1,11 @@
 require_relative '../../spec_helper'
 
 describe "ENV.delete" do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
   after :each do
-    ENV.delete("foo")
+    ENV["foo"] = @saved_foo
   end
 
   it "removes the variable from the environment" do
@@ -16,9 +19,37 @@ describe "ENV.delete" do
     ENV.delete("foo").should == "bar"
   end
 
+  it "returns nil if the named environment variable does not exist and no block given" do
+    ENV.delete("foo")
+    ENV.delete("foo").should == nil
+  end
+
   it "yields the name to the given block if the named environment variable does not exist" do
     ENV.delete("foo")
     ENV.delete("foo") { |name| ScratchPad.record name }
     ScratchPad.recorded.should == "foo"
   end
+
+  it "returns the result of given block if the named environment variable does not exist" do
+    ENV.delete("foo")
+    ENV.delete("foo") { |name| "bar" }.should == "bar"
+  end
+
+  it "does not evaluate the block if the environment variable exists" do
+    ENV["foo"] = "bar"
+    ENV.delete("foo") { |name| fail "Should not happen" }
+    ENV["foo"].should == nil
+  end
+
+  it "removes the variable coerced with #to_str" do
+    ENV["foo"] = "bar"
+    k = mock('key')
+    k.should_receive(:to_str).and_return("foo")
+    ENV.delete(k)
+    ENV["foo"].should == nil
+  end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> { ENV.delete(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
 end
diff --git a/spec/ruby/core/env/dup_spec.rb b/spec/ruby/core/env/dup_spec.rb
new file mode 100644
index 0000000000..d8cfac891d
--- /dev/null
+++ b/spec/ruby/core/env/dup_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+
+describe "ENV#dup" do
+  it "raises TypeError" do
+    -> {
+      ENV.dup
+    }.should.raise(TypeError, /Cannot dup ENV, use ENV.to_h to get a copy of ENV as a hash/)
+  end
+end
diff --git a/spec/ruby/core/env/each_key_spec.rb b/spec/ruby/core/env/each_key_spec.rb
index 294bf39912..ad2cb560a0 100644
--- a/spec/ruby/core/env/each_key_spec.rb
+++ b/spec/ruby/core/env/each_key_spec.rb
@@ -10,16 +10,18 @@ describe "ENV.each_key" do
       ENV.clear
       ENV["1"] = "3"
       ENV["2"] = "4"
-      ENV.each_key { |k| e << k }
-      e.should include("1")
-      e.should include("2")
+      ENV.each_key { |k| e << k }.should.equal?(ENV)
+      e.should.include?("1")
+      e.should.include?("2")
     ensure
       ENV.replace orig
     end
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.each_key.should be_an_instance_of(Enumerator)
+    enum = ENV.each_key
+    enum.should.instance_of?(Enumerator)
+    enum.to_a.should == ENV.keys
   end
 
   it "returns keys in the locale encoding" do
diff --git a/spec/ruby/core/env/each_pair_spec.rb b/spec/ruby/core/env/each_pair_spec.rb
index 01082dd419..2d7ed5faa0 100644
--- a/spec/ruby/core/env/each_pair_spec.rb
+++ b/spec/ruby/core/env/each_pair_spec.rb
@@ -1,4 +1,4 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 require_relative 'shared/each'
 
 describe "ENV.each_pair" do
diff --git a/spec/ruby/core/env/each_spec.rb b/spec/ruby/core/env/each_spec.rb
index 06d8be3124..d1e06f55b6 100644
--- a/spec/ruby/core/env/each_spec.rb
+++ b/spec/ruby/core/env/each_spec.rb
@@ -1,4 +1,4 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 require_relative 'shared/each'
 
 describe "ENV.each" do
diff --git a/spec/ruby/core/env/each_value_spec.rb b/spec/ruby/core/env/each_value_spec.rb
index 88f4bc49da..6f65e923e6 100644
--- a/spec/ruby/core/env/each_value_spec.rb
+++ b/spec/ruby/core/env/each_value_spec.rb
@@ -1,4 +1,4 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "ENV.each_value" do
@@ -10,21 +10,23 @@ describe "ENV.each_value" do
       ENV.clear
       ENV["1"] = "3"
       ENV["2"] = "4"
-      ENV.each_value { |v| e << v }
-      e.should include("3")
-      e.should include("4")
+      ENV.each_value { |v| e << v }.should.equal?(ENV)
+      e.should.include?("3")
+      e.should.include?("4")
     ensure
       ENV.replace orig
     end
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.each_value.should be_an_instance_of(Enumerator)
+    enum = ENV.each_value
+    enum.should.instance_of?(Enumerator)
+    enum.to_a.should == ENV.values
   end
 
   it "uses the locale encoding" do
     ENV.each_value do |value|
-      value.encoding.should == Encoding.find('locale')
+      value.should.be_locale_env
     end
   end
 
diff --git a/spec/ruby/core/env/element_reference_spec.rb b/spec/ruby/core/env/element_reference_spec.rb
index 59b53fc4b1..e3ac979418 100644
--- a/spec/ruby/core/env/element_reference_spec.rb
+++ b/spec/ruby/core/env/element_reference_spec.rb
@@ -1,5 +1,6 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 
 describe "ENV.[]" do
   before :each do
@@ -16,7 +17,18 @@ describe "ENV.[]" do
 
   it "returns only frozen values" do
     ENV[@variable] = "a non-frozen string"
-    ENV[@variable].frozen?.should == true
+    ENV[@variable].should.frozen?
+  end
+
+  it "coerces a non-string name with #to_str" do
+    ENV[@variable] = "bar"
+    k = mock('key')
+    k.should_receive(:to_str).and_return(@variable)
+    ENV[k].should == "bar"
+  end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> { ENV[Object.new] }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 
   platform_is :windows do
@@ -47,7 +59,7 @@ describe "ENV.[]" do
   it "uses the locale encoding if Encoding.default_internal is nil" do
     Encoding.default_internal = nil
 
-    locale = Encoding.find('locale')
+    locale = ENVSpecs.encoding
     locale = Encoding::BINARY if locale == Encoding::US_ASCII
     ENV[@variable] = "\xC3\xB8"
     ENV[@variable].encoding.should == locale
@@ -59,6 +71,6 @@ describe "ENV.[]" do
     ENV[@variable] = ""
     Encoding.default_internal = Encoding::IBM437
 
-    ENV[@variable].encoding.should equal(Encoding::IBM437)
+    ENV[@variable].encoding.should.equal?(Encoding::IBM437)
   end
 end
diff --git a/spec/ruby/core/env/empty_spec.rb b/spec/ruby/core/env/empty_spec.rb
index 7ef17d244f..afeb406a9e 100644
--- a/spec/ruby/core/env/empty_spec.rb
+++ b/spec/ruby/core/env/empty_spec.rb
@@ -4,12 +4,12 @@ describe "ENV.empty?" do
 
   it "returns true if the Environment is empty" do
     if ENV.keys.size > 0
-      ENV.empty?.should == false
+      ENV.should_not.empty?
     end
     orig = ENV.to_hash
     begin
       ENV.clear
-      ENV.empty?.should == true
+      ENV.should.empty?
     ensure
       ENV.replace orig
     end
@@ -17,7 +17,7 @@ describe "ENV.empty?" do
 
   it "returns false if not empty" do
     if ENV.keys.size > 0
-      ENV.empty?.should == false
+      ENV.should_not.empty?
     end
   end
 end
diff --git a/spec/ruby/core/env/except_spec.rb b/spec/ruby/core/env/except_spec.rb
new file mode 100644
index 0000000000..fb8f3b7536
--- /dev/null
+++ b/spec/ruby/core/env/except_spec.rb
@@ -0,0 +1,34 @@
+require_relative 'spec_helper'
+require_relative 'shared/to_hash'
+
+describe "ENV.except" do
+  before do
+    @orig_hash = ENV.to_hash
+  end
+
+  after do
+    ENV.replace @orig_hash
+  end
+
+  # Testing the method without arguments is covered via
+  it_behaves_like :env_to_hash, :except
+
+  it "returns a hash without the requested subset" do
+    ENV.clear
+
+    ENV['one'] = '1'
+    ENV['two'] = '2'
+    ENV['three'] = '3'
+
+    ENV.except('one', 'three').should == { 'two' => '2' }
+  end
+
+  it "ignores keys not present in the original hash" do
+    ENV.clear
+
+    ENV['one'] = '1'
+    ENV['two'] = '2'
+
+    ENV.except('one', 'three').should == { 'two' => '2' }
+  end
+end
diff --git a/spec/ruby/core/env/fetch_spec.rb b/spec/ruby/core/env/fetch_spec.rb
index eeaf290cf0..a2ec79c62b 100644
--- a/spec/ruby/core/env/fetch_spec.rb
+++ b/spec/ruby/core/env/fetch_spec.rb
@@ -1,15 +1,22 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/hash/key_error'
+require_relative 'fixtures/common'
 
 describe "ENV.fetch" do
+  before :each do
+    @foo_saved = ENV.delete("foo")
+  end
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
   it "returns a value" do
     ENV["foo"] = "bar"
     ENV.fetch("foo").should == "bar"
-    ENV.delete "foo"
   end
 
   it "raises a TypeError if the key is not a String" do
-    -> { ENV.fetch :should_never_be_set }.should raise_error(TypeError)
+    -> { ENV.fetch Object.new }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 
   context "when the key is not found" do
@@ -18,25 +25,39 @@ describe "ENV.fetch" do
     it "formats the object with #inspect in the KeyError message" do
       -> {
         ENV.fetch('foo')
-      }.should raise_error(KeyError, 'key not found: "foo"')
+      }.should.raise(KeyError, 'key not found: "foo"')
     end
   end
 
   it "provides the given default parameter" do
-    ENV.fetch("should_never_be_set", "default").should == "default"
+    ENV.fetch("foo", "default").should == "default"
+  end
+
+  it "does not insist that the default be a String" do
+    ENV.fetch("foo", :default).should == :default
   end
 
   it "provides a default value from a block" do
-    ENV.fetch("should_never_be_set") { |k| "wanted #{k}" }.should == "wanted should_never_be_set"
+    ENV.fetch("foo") { |k| "wanted #{k}" }.should == "wanted foo"
+  end
+
+  it "does not insist that the block return a String" do
+    ENV.fetch("foo") { |k| k.to_sym }.should == :foo
   end
 
   it "warns on block and default parameter given" do
     -> do
-       ENV.fetch("should_never_be_set", "default") { 1 }.should == 1
+      ENV.fetch("foo", "default") { "bar" }.should == "bar"
     end.should complain(/block supersedes default value argument/)
   end
 
+  it "does not evaluate the block when key found" do
+    ENV["foo"] = "bar"
+    ENV.fetch("foo") { fail "should not get here"}.should == "bar"
+  end
+
   it "uses the locale encoding" do
-    ENV.fetch(ENV.keys.first).encoding.should == Encoding.find('locale')
+    ENV["foo"] = "bar"
+    ENV.fetch("foo").encoding.should == ENVSpecs.encoding
   end
 end
diff --git a/spec/ruby/core/env/fetch_values_spec.rb b/spec/ruby/core/env/fetch_values_spec.rb
new file mode 100644
index 0000000000..302cde2fd1
--- /dev/null
+++ b/spec/ruby/core/env/fetch_values_spec.rb
@@ -0,0 +1,51 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+
+ruby_version_is "4.1" do
+  describe "ENV.fetch_values" do
+    before :each do
+      @saved_foo = ENV["foo"]
+      @saved_bar = ENV["bar"]
+      ENV.delete("foo")
+      ENV.delete("bar")
+    end
+
+    after :each do
+      ENV["foo"] = @saved_foo
+      ENV["bar"] = @saved_bar
+    end
+
+    it "returns an array of the values corresponding to the given keys" do
+      ENV["foo"] = "oof"
+      ENV["bar"] = "rab"
+      ENV.fetch_values("bar", "foo").should == ["rab", "oof"]
+    end
+
+    it "returns the default value from block" do
+      ENV["foo"] = "oof"
+      ENV.fetch_values("bar") { |key| "`#{key}' is not found" }.should == ["`bar' is not found"]
+      ENV.fetch_values("bar", "foo") { |key| "`#{key}' is not found" }.should == ["`bar' is not found", "oof"]
+    end
+
+    it "returns an empty array if no keys specified" do
+      ENV.fetch_values.should == []
+    end
+
+    it "raises KeyError when there is no matching key" do
+      ENV["foo"] = "oof"
+      ENV["bar"] = "rab"
+      -> {
+        ENV.fetch_values("bar", "y", "foo", "z")
+      }.should.raise(KeyError, 'key not found: "y"')
+    end
+
+    it "uses the locale encoding" do
+      ENV.fetch_values(ENV.keys.first).first.encoding.should == ENVSpecs.encoding
+    end
+
+    it "raises TypeError when a key is not coercible to String" do
+      ENV["foo"] = "oof"
+      -> { ENV.fetch_values("foo", Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+    end
+  end
+end
diff --git a/spec/ruby/core/env/filter_spec.rb b/spec/ruby/core/env/filter_spec.rb
index ba18a3b33b..52f8b79a0b 100644
--- a/spec/ruby/core/env/filter_spec.rb
+++ b/spec/ruby/core/env/filter_spec.rb
@@ -2,14 +2,12 @@ require_relative '../../spec_helper'
 require_relative '../enumerable/shared/enumeratorized'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "ENV.filter!" do
-    it_behaves_like :env_select!, :filter!
-    it_behaves_like :enumeratorized_with_origin_size, :filter!, ENV
-  end
+describe "ENV.filter!" do
+  it_behaves_like :env_select!, :filter!
+  it_behaves_like :enumeratorized_with_origin_size, :filter!, ENV
+end
 
-  describe "ENV.filter" do
-    it_behaves_like :env_select, :filter
-    it_behaves_like :enumeratorized_with_origin_size, :filter, ENV
-  end
+describe "ENV.filter" do
+  it_behaves_like :env_select, :filter
+  it_behaves_like :enumeratorized_with_origin_size, :filter, ENV
 end
diff --git a/spec/ruby/core/env/fixtures/common.rb b/spec/ruby/core/env/fixtures/common.rb
new file mode 100644
index 0000000000..8d5057614d
--- /dev/null
+++ b/spec/ruby/core/env/fixtures/common.rb
@@ -0,0 +1,9 @@
+module ENVSpecs
+  def self.encoding
+    locale = Encoding.find('locale')
+    if ruby_version_is '3' and platform_is :windows
+      locale = Encoding::UTF_8
+    end
+    locale
+  end
+end
diff --git a/spec/ruby/core/env/index_spec.rb b/spec/ruby/core/env/index_spec.rb
deleted file mode 100644
index 04986a0421..0000000000
--- a/spec/ruby/core/env/index_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/key'
-
-describe "ENV.index" do
-  it_behaves_like :env_key, :index
-end
diff --git a/spec/ruby/core/env/indexes_spec.rb b/spec/ruby/core/env/indexes_spec.rb
deleted file mode 100644
index e724feaa39..0000000000
--- a/spec/ruby/core/env/indexes_spec.rb
+++ /dev/null
@@ -1 +0,0 @@
-require_relative '../../spec_helper'
diff --git a/spec/ruby/core/env/indices_spec.rb b/spec/ruby/core/env/indices_spec.rb
deleted file mode 100644
index e724feaa39..0000000000
--- a/spec/ruby/core/env/indices_spec.rb
+++ /dev/null
@@ -1 +0,0 @@
-require_relative '../../spec_helper'
diff --git a/spec/ruby/core/env/inspect_spec.rb b/spec/ruby/core/env/inspect_spec.rb
index 3c611c24a1..7dd92b120f 100644
--- a/spec/ruby/core/env/inspect_spec.rb
+++ b/spec/ruby/core/env/inspect_spec.rb
@@ -4,7 +4,7 @@ describe "ENV.inspect" do
 
   it "returns a String that looks like a Hash with real data" do
     ENV["foo"] = "bar"
-    ENV.inspect.should =~ /\{.*"foo"=>"bar".*\}/
+    ENV.inspect.should =~ /\{.*"foo" *=> *"bar".*\}/
     ENV.delete "foo"
   end
 
diff --git a/spec/ruby/core/env/keep_if_spec.rb b/spec/ruby/core/env/keep_if_spec.rb
index cf8e27936e..f24981e216 100644
--- a/spec/ruby/core/env/keep_if_spec.rb
+++ b/spec/ruby/core/env/keep_if_spec.rb
@@ -3,30 +3,51 @@ require_relative '../enumerable/shared/enumeratorized'
 
 describe "ENV.keep_if" do
   before :each do
-    ENV["foo"] = "bar"
+    @foo = ENV["foo"]
+    @bar = ENV["bar"]
+
+    ENV["foo"] = "0"
+    ENV["bar"] = "1"
   end
 
   after :each do
-    ENV.delete "foo"
+    ENV["foo"] = @foo
+    ENV["bar"] = @bar
   end
 
   it "deletes pairs if the block returns false" do
-    ENV.keep_if { |k, v| k != "foo" }
+    ENV.keep_if { |k, v| !["foo", "bar"].include?(k) }
     ENV["foo"].should == nil
+    ENV["bar"].should == nil
+  end
+
+  it "returns ENV when block given" do
+    ENV.keep_if { |k, v| !["foo", "bar"].include?(k) }.should.equal?(ENV)
   end
 
   it "returns ENV even if nothing deleted" do
-    ENV.keep_if { true }.should_not == nil
+    ENV.keep_if { true }.should.equal?(ENV)
   end
 
   it "returns an Enumerator if no block given" do
-    ENV.keep_if.should be_an_instance_of(Enumerator)
+    ENV.keep_if.should.instance_of?(Enumerator)
   end
 
   it "deletes pairs through enumerator" do
     enum = ENV.keep_if
-    enum.each { |k, v| k != "foo" }
+    enum.each { |k, v| !["foo", "bar"].include?(k) }
     ENV["foo"].should == nil
+    ENV["bar"].should == nil
+  end
+
+  it "returns ENV from enumerator" do
+    enum = ENV.keep_if
+    enum.each { |k, v| !["foo", "bar"].include?(k) }.should.equal?(ENV)
+  end
+
+  it "returns ENV from enumerator even if nothing deleted" do
+    enum = ENV.keep_if
+    enum.each { true }.should.equal?(ENV)
   end
 
   it_behaves_like :enumeratorized_with_origin_size, :keep_if, ENV
diff --git a/spec/ruby/core/env/key_spec.rb b/spec/ruby/core/env/key_spec.rb
index 82cfbefa39..677cf35216 100644
--- a/spec/ruby/core/env/key_spec.rb
+++ b/spec/ruby/core/env/key_spec.rb
@@ -1,11 +1,39 @@
 require_relative '../../spec_helper'
 require_relative 'shared/include'
-require_relative 'shared/key'
 
 describe "ENV.key?" do
   it_behaves_like :env_include, :key?
 end
 
 describe "ENV.key" do
-  it_behaves_like :env_key, :key
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
+  it "returns the index associated with the passed value" do
+    ENV["foo"] = "bar"
+    ENV.key("bar").should == "foo"
+  end
+
+  it "returns nil if the passed value is not found" do
+    ENV.delete("foo")
+    ENV.key("foo").should == nil
+  end
+
+  it "coerces the key element with #to_str" do
+    ENV["foo"] = "bar"
+    k = mock('key')
+    k.should_receive(:to_str).and_return("bar")
+    ENV.key(k).should == "foo"
+  end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> {
+      ENV.key(Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
 end
diff --git a/spec/ruby/core/env/keys_spec.rb b/spec/ruby/core/env/keys_spec.rb
index 3699b2c225..b074a8f7c7 100644
--- a/spec/ruby/core/env/keys_spec.rb
+++ b/spec/ruby/core/env/keys_spec.rb
@@ -2,8 +2,8 @@ require_relative '../../spec_helper'
 
 describe "ENV.keys" do
 
-  it "returns all the keys" do
-    ENV.keys.sort.should == ENV.to_hash.keys.sort
+  it "returns an array of the keys" do
+    ENV.keys.should == ENV.to_hash.keys
   end
 
   it "returns the keys in the locale encoding" do
diff --git a/spec/ruby/core/env/length_spec.rb b/spec/ruby/core/env/length_spec.rb
index 536af9edf5..c6f9062892 100644
--- a/spec/ruby/core/env/length_spec.rb
+++ b/spec/ruby/core/env/length_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/length'
 
 describe "ENV.length" do
- it_behaves_like :env_length, :length
+  it_behaves_like :env_length, :length
 end
diff --git a/spec/ruby/core/env/merge_spec.rb b/spec/ruby/core/env/merge_spec.rb
index b418cd11f4..f10662cf79 100644
--- a/spec/ruby/core/env/merge_spec.rb
+++ b/spec/ruby/core/env/merge_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/update'
 
-ruby_version_is "2.7" do
-  describe "ENV.merge!" do
-    it_behaves_like :env_update, :merge!
-  end
+describe "ENV.merge!" do
+  it_behaves_like :env_update, :merge!
 end
diff --git a/spec/ruby/core/env/rassoc_spec.rb b/spec/ruby/core/env/rassoc_spec.rb
index 4b839c15c7..e4ac5ce5e2 100644
--- a/spec/ruby/core/env/rassoc_spec.rb
+++ b/spec/ruby/core/env/rassoc_spec.rb
@@ -1,8 +1,14 @@
 require_relative '../../spec_helper'
 
 describe "ENV.rassoc" do
+  before :each do
+    @foo = ENV["foo"]
+    @baz = ENV["baz"]
+  end
+
   after :each do
-    ENV.delete("foo")
+    ENV["foo"] = @foo
+    ENV["baz"] = @baz
   end
 
   it "returns an array of the key and value of the environment variable with the given value" do
@@ -10,6 +16,15 @@ describe "ENV.rassoc" do
     ENV.rassoc("bar").should == ["foo", "bar"]
   end
 
+  it "returns a single array even if there are multiple such environment variables" do
+    ENV["foo"] = "bar"
+    ENV["baz"] = "bar"
+    [
+        ["foo", "bar"],
+        ["baz", "bar"],
+    ].should.include?(ENV.rassoc("bar"))
+  end
+
   it "returns nil if no environment variable with the given value exists" do
     ENV.rassoc("bar").should == nil
   end
@@ -20,4 +35,8 @@ describe "ENV.rassoc" do
     v.should_receive(:to_str).and_return("bar")
     ENV.rassoc(v).should == ["foo", "bar"]
   end
+
+  it "returns nil if the argument is not a String and does not respond to #to_str" do
+    ENV.rassoc(Object.new).should == nil
+  end
 end
diff --git a/spec/ruby/core/env/rehash_spec.rb b/spec/ruby/core/env/rehash_spec.rb
index e724feaa39..3782e4b727 100644
--- a/spec/ruby/core/env/rehash_spec.rb
+++ b/spec/ruby/core/env/rehash_spec.rb
@@ -1 +1,7 @@
 require_relative '../../spec_helper'
+
+describe "ENV.rehash" do
+  it "returns nil" do
+    ENV.rehash.should == nil
+  end
+end
diff --git a/spec/ruby/core/env/reject_spec.rb b/spec/ruby/core/env/reject_spec.rb
index 1026c2f451..4df864493d 100644
--- a/spec/ruby/core/env/reject_spec.rb
+++ b/spec/ruby/core/env/reject_spec.rb
@@ -2,6 +2,14 @@ require_relative '../../spec_helper'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "ENV.reject!" do
+  before :each do
+    @foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @foo
+  end
+
   it "rejects entries based on key" do
     ENV["foo"] = "bar"
     ENV.reject! { |k, v| k == "foo" }
@@ -17,19 +25,23 @@ describe "ENV.reject!" do
   it "returns itself or nil" do
     ENV.reject! { false }.should == nil
     ENV["foo"] = "bar"
-    ENV.reject! { |k, v| k == "foo" }.should == ENV
+    ENV.reject! { |k, v| k == "foo" }.should.equal?(ENV)
     ENV["foo"].should == nil
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.reject!.should be_an_instance_of(Enumerator)
+    ENV["foo"] = "bar"
+    enum = ENV.reject!
+    enum.should.instance_of?(Enumerator)
+    enum.each { |k, v| k == "foo" }.should.equal?(ENV)
+    ENV["foo"].should == nil
   end
 
   it "doesn't raise if empty" do
     orig = ENV.to_hash
     begin
       ENV.clear
-      -> { ENV.reject! }.should_not raise_error(LocalJumpError)
+      -> { ENV.reject! }.should_not.raise(LocalJumpError)
     ensure
       ENV.replace orig
     end
@@ -39,6 +51,14 @@ describe "ENV.reject!" do
 end
 
 describe "ENV.reject" do
+  before :each do
+    @foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @foo
+  end
+
   it "rejects entries based on key" do
     ENV["foo"] = "bar"
     e = ENV.reject { |k, v| k == "foo" }
@@ -56,18 +76,22 @@ describe "ENV.reject" do
   end
 
   it "returns a Hash" do
-    ENV.reject { false }.should be_kind_of(Hash)
+    ENV.reject { false }.should.is_a?(Hash)
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.reject.should be_an_instance_of(Enumerator)
+    ENV["foo"] = "bar"
+    enum = ENV.reject
+    enum.should.instance_of?(Enumerator)
+    enum.each { |k, v| k == "foo"}
+    ENV["foo"] = nil
   end
 
   it "doesn't raise if empty" do
     orig = ENV.to_hash
     begin
       ENV.clear
-      -> { ENV.reject }.should_not raise_error(LocalJumpError)
+      -> { ENV.reject }.should_not.raise(LocalJumpError)
     ensure
       ENV.replace orig
     end
diff --git a/spec/ruby/core/env/replace_spec.rb b/spec/ruby/core/env/replace_spec.rb
index 8837deea4a..27eb3e45dd 100644
--- a/spec/ruby/core/env/replace_spec.rb
+++ b/spec/ruby/core/env/replace_spec.rb
@@ -1,15 +1,51 @@
 require_relative '../../spec_helper'
 
 describe "ENV.replace" do
+  before :each do
+    @orig = ENV.to_hash
+    ENV.delete("foo")
+  end
+
+  after :each do
+    ENV.replace(@orig)
+  end
 
   it "replaces ENV with a Hash" do
-    ENV["foo"] = "bar"
-    e = ENV.reject { |k, v| k == "foo" }
-    e["baz"] = "bam"
-    ENV.replace e
-    ENV["foo"].should == nil
-    ENV["baz"].should == "bam"
-    ENV.delete "baz"
+    ENV.replace("foo" => "0", "bar" => "1").should.equal?(ENV)
+    ENV.size.should == 2
+    ENV["foo"].should == "0"
+    ENV["bar"].should == "1"
+  end
+
+  it "raises TypeError if the argument is not a Hash" do
+    -> { ENV.replace(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into Hash")
+    ENV.to_hash.should == @orig
+  end
+
+  it "raises TypeError if a key is not a String" do
+    -> { ENV.replace(Object.new => "0") }.should.raise(TypeError, "no implicit conversion of Object into String")
+    ENV.to_hash.should == @orig
+  end
+
+  it "raises TypeError if a value is not a String" do
+    -> { ENV.replace("foo" => Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+    ENV.to_hash.should == @orig
+  end
+
+  it "raises Errno::EINVAL when the key contains the '=' character" do
+    -> { ENV.replace("foo=" =>"bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "raises Errno::EINVAL when the key is an empty string" do
+    -> { ENV.replace("" => "bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "does not accept good data preceding an error" do
+    -> { ENV.replace("foo" => "1", Object.new => Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 
+  it "does not accept good data following an error" do
+    -> { ENV.replace(Object.new => Object.new, "foo" => "0") }.should.raise(TypeError, "no implicit conversion of Object into String")
+    ENV.to_hash.should == @orig
+  end
 end
diff --git a/spec/ruby/core/env/shared/each.rb b/spec/ruby/core/env/shared/each.rb
index 261ad3a2a6..0661ca924c 100644
--- a/spec/ruby/core/env/shared/each.rb
+++ b/spec/ruby/core/env/shared/each.rb
@@ -8,16 +8,20 @@ describe :env_each, shared: true do
       ENV.clear
       ENV["foo"] = "bar"
       ENV["baz"] = "boo"
-      ENV.send(@method) { |k, v| e << [k, v] }.should equal(ENV)
-      e.should include(["foo", "bar"])
-      e.should include(["baz", "boo"])
+      ENV.send(@method) { |k, v| e << [k, v] }.should.equal?(ENV)
+      e.should.include?(["foo", "bar"])
+      e.should.include?(["baz", "boo"])
     ensure
       ENV.replace orig
     end
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.send(@method).should be_an_instance_of(Enumerator)
+    enum = ENV.send(@method)
+    enum.should.instance_of?(Enumerator)
+    enum.each do |name, value|
+      ENV[name].should == value
+    end
   end
 
   before :all do
@@ -31,8 +35,6 @@ describe :env_each, shared: true do
       @internal = Encoding.default_internal
 
       Encoding.default_external = Encoding::BINARY
-
-      @locale_encoding = Encoding.find "locale"
     end
 
     after :each do
@@ -44,8 +46,8 @@ describe :env_each, shared: true do
       Encoding.default_internal = nil
 
       ENV.send(@method) do |key, value|
-        key.encoding.should equal(@locale_encoding)
-        value.encoding.should equal(@locale_encoding)
+        key.should.be_locale_env
+        value.should.be_locale_env
       end
     end
 
@@ -53,9 +55,9 @@ describe :env_each, shared: true do
       Encoding.default_internal = internal = Encoding::IBM437
 
       ENV.send(@method) do |key, value|
-        key.encoding.should equal(internal)
+        key.encoding.should.equal?(internal)
         if value.ascii_only?
-          value.encoding.should equal(internal)
+          value.encoding.should.equal?(internal)
         end
       end
     end
diff --git a/spec/ruby/core/env/shared/include.rb b/spec/ruby/core/env/shared/include.rb
index 8d8311dcf2..ceca02e3eb 100644
--- a/spec/ruby/core/env/shared/include.rb
+++ b/spec/ruby/core/env/shared/include.rb
@@ -1,11 +1,30 @@
 describe :env_include, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
   it "returns true if ENV has the key" do
     ENV["foo"] = "bar"
     ENV.send(@method, "foo").should == true
-    ENV.delete "foo"
   end
 
   it "returns false if ENV doesn't include the key" do
-    ENV.send(@method, "should_never_be_set").should == false
+    ENV.delete("foo")
+    ENV.send(@method, "foo").should == false
+  end
+
+  it "coerces the key with #to_str" do
+    ENV["foo"] = "bar"
+    k = mock('key')
+    k.should_receive(:to_str).and_return("foo")
+    ENV.send(@method, k).should == true
+  end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> { ENV.send(@method, Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 end
diff --git a/spec/ruby/core/env/shared/key.rb b/spec/ruby/core/env/shared/key.rb
deleted file mode 100644
index 43299beadb..0000000000
--- a/spec/ruby/core/env/shared/key.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-describe :env_key, shared: true do
-  it "returns the index associated with the passed value" do
-    ENV["foo"] = "bar"
-    ENV.send(@method, "bar").should == "foo"
-    ENV.delete "foo"
-  end
-
-  it "returns nil if the passed value is not found" do
-    ENV.send(@method, "should_never_be_set").should be_nil
-  end
-end
diff --git a/spec/ruby/core/env/shared/select.rb b/spec/ruby/core/env/shared/select.rb
index a0b46a775a..8ec648a637 100644
--- a/spec/ruby/core/env/shared/select.rb
+++ b/spec/ruby/core/env/shared/select.rb
@@ -1,16 +1,38 @@
 describe :env_select, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
   it "returns a Hash of names and values for which block return true" do
     ENV["foo"] = "bar"
     (ENV.send(@method) { |k, v| k == "foo" }).should == { "foo" => "bar" }
-    ENV.delete "foo"
   end
 
   it "returns an Enumerator when no block is given" do
-    ENV.send(@method).should be_an_instance_of(Enumerator)
+    enum = ENV.send(@method)
+    enum.should.instance_of?(Enumerator)
+  end
+
+  it "selects via the enumerator" do
+    enum = ENV.send(@method)
+    ENV["foo"] = "bar"
+    enum.each { |k, v| k == "foo" }.should == { "foo" => "bar"}
   end
 end
 
 describe :env_select!, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
   it "removes environment variables for which the block returns true" do
     ENV["foo"] = "bar"
     ENV.send(@method) { |k, v| k != "foo" }
@@ -27,6 +49,13 @@ describe :env_select!, shared: true do
   end
 
   it "returns an Enumerator if called without a block" do
-    ENV.send(@method).should be_an_instance_of(Enumerator)
+    ENV.send(@method).should.instance_of?(Enumerator)
+  end
+
+  it "selects via the enumerator" do
+    enum = ENV.send(@method)
+    ENV["foo"] = "bar"
+    enum.each { |k, v| k != "foo" }
+    ENV["foo"].should == nil
   end
 end
diff --git a/spec/ruby/core/env/shared/store.rb b/spec/ruby/core/env/shared/store.rb
index 6ae91ef8fc..388208a8ac 100644
--- a/spec/ruby/core/env/shared/store.rb
+++ b/spec/ruby/core/env/shared/store.rb
@@ -1,6 +1,10 @@
 describe :env_store, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
   after :each do
-    ENV.delete("foo")
+    ENV["foo"] = @saved_foo
   end
 
   it "sets the environment variable to the given value" do
@@ -10,13 +14,13 @@ describe :env_store, shared: true do
 
   it "returns the value" do
     value = "bar"
-    ENV.send(@method, "foo", value).should equal(value)
+    ENV.send(@method, "foo", value).should.equal?(value)
   end
 
   it "deletes the environment variable when the value is nil" do
     ENV["foo"] = "bar"
     ENV.send(@method, "foo", nil)
-    ENV.key?("foo").should be_false
+    ENV.key?("foo").should == false
   end
 
   it "coerces the key argument with #to_str" do
@@ -34,23 +38,23 @@ describe :env_store, shared: true do
   end
 
   it "raises TypeError when the key is not coercible to String" do
-    -> { ENV.send(@method, Object.new, "bar") }.should raise_error(TypeError)
+    -> { ENV.send(@method, Object.new, "bar") }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 
   it "raises TypeError when the value is not coercible to String" do
-    -> { ENV.send(@method, "foo", Object.new) }.should raise_error(TypeError)
+    -> { ENV.send(@method, "foo", Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 
   it "raises Errno::EINVAL when the key contains the '=' character" do
-    -> { ENV.send(@method, "foo=", "bar") }.should raise_error(Errno::EINVAL)
+    -> { ENV.send(@method, "foo=", "bar") }.should.raise(Errno::EINVAL)
   end
 
   it "raises Errno::EINVAL when the key is an empty string" do
-    -> { ENV.send(@method, "", "bar") }.should raise_error(Errno::EINVAL)
+    -> { ENV.send(@method, "", "bar") }.should.raise(Errno::EINVAL)
   end
 
   it "does nothing when the key is not a valid environment variable key and the value is nil" do
     ENV.send(@method, "foo=", nil)
-    ENV.key?("foo=").should be_false
+    ENV.key?("foo=").should == false
   end
 end
diff --git a/spec/ruby/core/env/shared/to_hash.rb b/spec/ruby/core/env/shared/to_hash.rb
index 254054c14d..7868690c38 100644
--- a/spec/ruby/core/env/shared/to_hash.rb
+++ b/spec/ruby/core/env/shared/to_hash.rb
@@ -1,22 +1,33 @@
 describe :env_to_hash, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"]= @saved_foo
+  end
+
   it "returns the ENV as a hash" do
     ENV["foo"] = "bar"
     h = ENV.send(@method)
-    h.should be_an_instance_of(Hash)
+    h.should.instance_of?(Hash)
     h["foo"].should == "bar"
-    ENV.delete "foo"
   end
 
   it "uses the locale encoding for keys" do
-    ENV.send(@method).keys.all? {|k| k.encoding == Encoding.find('locale') }.should be_true
+    ENV.send(@method).keys.each {|k| k.should.be_locale_env }
   end
 
   it "uses the locale encoding for values" do
-    ENV.send(@method).values.all? {|v| v.encoding == Encoding.find('locale') }.should be_true
+    ENV.send(@method).values.each {|k| k.should.be_locale_env }
   end
 
   it "duplicates the ENV when converting to a Hash" do
     h = ENV.send(@method)
-    h.should_not equal ENV
+    h.should_not.equal? ENV
+    h.size.should == ENV.size
+    h.each_pair do |k, v|
+      ENV[k].should == v
+    end
   end
 end
diff --git a/spec/ruby/core/env/shared/update.rb b/spec/ruby/core/env/shared/update.rb
index cd09877243..112cc2505d 100644
--- a/spec/ruby/core/env/shared/update.rb
+++ b/spec/ruby/core/env/shared/update.rb
@@ -1,21 +1,104 @@
 describe :env_update, shared: true do
-  it "adds the parameter hash to ENV" do
-    ENV["foo"].should == nil
-    ENV.send @method, "foo" => "bar"
-    ENV["foo"].should == "bar"
-    ENV.delete "foo"
-  end
-
-  it "yields key, the old value and the new value when replacing entries" do
-    ENV.send @method, "foo" => "bar"
-    ENV["foo"].should == "bar"
-    ENV.send(@method, "foo" => "boo") do |key, old, new|
-      key.should == "foo"
-      old.should == "bar"
-      new.should == "boo"
-      "rab"
+  before :each do
+    @saved_foo = ENV["foo"]
+    @saved_bar = ENV["bar"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+    ENV["bar"] = @saved_bar
+  end
+
+  it "adds the parameter hash to ENV, returning ENV" do
+    ENV.send(@method, "foo" => "0", "bar" => "1").should.equal?(ENV)
+    ENV["foo"].should == "0"
+    ENV["bar"].should == "1"
+  end
+
+  it "adds the multiple parameter hashes to ENV, returning ENV" do
+    ENV.send(@method, {"foo" => "multi1"}, {"bar" => "multi2"}).should.equal?(ENV)
+    ENV["foo"].should == "multi1"
+    ENV["bar"].should == "multi2"
+  end
+
+  it "returns ENV when no block given" do
+    ENV.send(@method, {"foo" => "0", "bar" => "1"}).should.equal?(ENV)
+  end
+
+  it "yields key, the old value and the new value when replacing an entry" do
+    ENV.send @method, {"foo" => "0", "bar" => "3"}
+    a = []
+    ENV.send @method, {"foo" => "1", "bar" => "4"} do |key, old, new|
+      a << [key, old, new]
+      new
+    end
+    a[0].should == ["foo", "0", "1"]
+    a[1].should == ["bar", "3", "4"]
+  end
+
+  it "yields key, the old value and the new value when replacing an entry" do
+    ENV.send @method, {"foo" => "0", "bar" => "3"}
+    ENV.send @method, {"foo" => "1", "bar" => "4"} do |key, old, new|
+      (new.to_i + 1).to_s
+    end
+    ENV["foo"].should == "2"
+    ENV["bar"].should == "5"
+  end
+
+  # BUG: https://bugs.ruby-lang.org/issues/16192
+  it "does not evaluate the block when the name is new" do
+    ENV.delete("bar")
+    ENV.send @method, {"foo" => "0"}
+    ENV.send(@method, "bar" => "1") { |key, old, new| fail "Should not get here" }
+    ENV["bar"].should == "1"
+  end
+
+  # BUG: https://bugs.ruby-lang.org/issues/16192
+  it "does not use the block's return value as the value when the name is new" do
+    ENV.delete("bar")
+    ENV.send @method, {"foo" => "0"}
+    ENV.send(@method, "bar" => "1") { |key, old, new| "Should not use this value" }
+    ENV["foo"].should == "0"
+    ENV["bar"].should == "1"
+  end
+
+  it "returns ENV when block given" do
+    ENV.send(@method, {"foo" => "0", "bar" => "1"}){}.should.equal?(ENV)
+  end
+
+  it "raises TypeError when a name is not coercible to String" do
+    -> { ENV.send @method, Object.new => "0" }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises TypeError when a value is not coercible to String" do
+    -> { ENV.send @method, "foo" => Object.new }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises Errno::EINVAL when a name contains the '=' character" do
+    -> { ENV.send(@method, "foo=" => "bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "raises Errno::EINVAL when a name is an empty string" do
+    -> { ENV.send(@method, "" => "bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "updates good data preceding an error" do
+    ENV["foo"] = "0"
+    begin
+      ENV.send @method, {"foo" => "2", Object.new => "1"}
+    rescue TypeError
+    ensure
+      ENV["foo"].should == "2"
+    end
+  end
+
+  it "does not update good data following an error" do
+    ENV["foo"] = "0"
+    begin
+      ENV.send @method, {Object.new => "1", "foo" => "2"}
+    rescue TypeError
+    ensure
+      ENV["foo"].should == "0"
     end
-    ENV["foo"].should == "rab"
-    ENV.delete "foo"
   end
 end
diff --git a/spec/ruby/core/env/shared/value.rb b/spec/ruby/core/env/shared/value.rb
index d9ee90f12d..c2b5025465 100644
--- a/spec/ruby/core/env/shared/value.rb
+++ b/spec/ruby/core/env/shared/value.rb
@@ -1,11 +1,29 @@
 describe :env_value, shared: true do
+  before :each do
+    @saved_foo = ENV["foo"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+  end
+
   it "returns true if ENV has the value" do
     ENV["foo"] = "bar"
     ENV.send(@method, "bar").should == true
-    ENV["foo"] = nil
   end
 
   it "returns false if ENV doesn't have the value" do
-    ENV.send(@method, "this_value_should_never_exist").should == false
+    ENV.send(@method, "foo").should == false
+  end
+
+  it "coerces the value element with #to_str" do
+    ENV["foo"] = "bar"
+    v = mock('value')
+    v.should_receive(:to_str).and_return("bar")
+    ENV.send(@method, v).should == true
+  end
+
+  it "returns nil if the argument is not a String and does not respond to #to_str" do
+    ENV.send(@method, Object.new).should == nil
   end
 end
diff --git a/spec/ruby/core/env/shift_spec.rb b/spec/ruby/core/env/shift_spec.rb
index c03b5d50c5..52bd0f9139 100644
--- a/spec/ruby/core/env/shift_spec.rb
+++ b/spec/ruby/core/env/shift_spec.rb
@@ -1,28 +1,5 @@
 require_relative '../../spec_helper'
-
-describe "ENV.shift" do
-  it "returns a pair and deletes it" do
-    ENV.empty?.should == false
-    orig = ENV.to_hash
-    begin
-      pair = ENV.shift
-      ENV.has_key?(pair.first).should == false
-    ensure
-      ENV.replace orig
-    end
-    ENV.has_key?(pair.first).should == true
-  end
-
-  it "returns nil if ENV.empty?" do
-    orig = ENV.to_hash
-    begin
-      ENV.clear
-      ENV.shift.should == nil
-    ensure
-      ENV.replace orig
-    end
-  end
-end
+require_relative 'fixtures/common'
 
 describe "ENV.shift" do
   before :each do
@@ -31,6 +8,7 @@ describe "ENV.shift" do
     @internal = Encoding.default_internal
 
     Encoding.default_external = Encoding::BINARY
+    ENV.replace({"FOO"=>"BAR"})
   end
 
   after :each do
@@ -39,19 +17,31 @@ describe "ENV.shift" do
     ENV.replace @orig
   end
 
+  it "returns a pair and deletes it" do
+    ENV.should.has_key?("FOO")
+    pair = ENV.shift
+    pair.should == ["FOO", "BAR"]
+    ENV.should_not.has_key?("FOO")
+  end
+
+  it "returns nil if ENV.empty?" do
+    ENV.clear
+    ENV.shift.should == nil
+  end
+
   it "uses the locale encoding if Encoding.default_internal is nil" do
     Encoding.default_internal = nil
 
     pair = ENV.shift
-    pair.first.encoding.should equal(Encoding.find("locale"))
-    pair.last.encoding.should equal(Encoding.find("locale"))
+    pair.first.encoding.should.equal?(ENVSpecs.encoding)
+    pair.last.encoding.should.equal?(ENVSpecs.encoding)
   end
 
   it "transcodes from the locale encoding to Encoding.default_internal if set" do
     Encoding.default_internal = Encoding::IBM437
 
     pair = ENV.shift
-    pair.first.encoding.should equal(Encoding::IBM437)
-    pair.last.encoding.should equal(Encoding::IBM437)
+    pair.first.encoding.should.equal?(Encoding::IBM437)
+    pair.last.encoding.should.equal?(Encoding::IBM437)
   end
 end
diff --git a/spec/ruby/core/env/size_spec.rb b/spec/ruby/core/env/size_spec.rb
index f050e9e5a9..7c8072481e 100644
--- a/spec/ruby/core/env/size_spec.rb
+++ b/spec/ruby/core/env/size_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/length'
 
 describe "ENV.size" do
- it_behaves_like :env_length, :size
+  it_behaves_like :env_length, :size
 end
diff --git a/spec/ruby/core/env/slice_spec.rb b/spec/ruby/core/env/slice_spec.rb
new file mode 100644
index 0000000000..4c0416547d
--- /dev/null
+++ b/spec/ruby/core/env/slice_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+
+describe "ENV.slice" do
+  before :each do
+    @saved_foo = ENV["foo"]
+    @saved_bar = ENV["bar"]
+    ENV["foo"] = "0"
+    ENV["bar"] = "1"
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+    ENV["bar"] = @saved_bar
+  end
+
+  it "returns a hash of the given environment variable names and their values" do
+    ENV.slice("foo", "bar").should == {"foo" => "0", "bar" => "1"}
+  end
+
+  it "ignores each String that is not an environment variable name" do
+    ENV.slice("foo", "boo", "bar").should == {"foo" => "0", "bar" => "1"}
+  end
+
+  it "returns the values for the keys coerced with #to_str, but keeps the original objects as result keys" do
+    foo = mock('key 1')
+    foo.should_receive(:to_str).and_return("foo")
+    boo = mock('key 2')
+    boo.should_receive(:to_str).and_return("boo")
+    bar = mock('key 3')
+    bar.should_receive(:to_str).and_return("bar")
+    ENV.slice(foo, boo, bar).should == {foo => "0", bar => "1"}
+  end
+
+  it "raises TypeError if any argument is not a String and does not respond to #to_str" do
+    -> { ENV.slice(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+end
diff --git a/spec/ruby/core/env/spec_helper.rb b/spec/ruby/core/env/spec_helper.rb
new file mode 100644
index 0000000000..470ffa58bc
--- /dev/null
+++ b/spec/ruby/core/env/spec_helper.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+locale_env_matcher = Class.new do
+  def initialize(name = 'locale')
+    encoding = Encoding.find(name)
+    @encodings = (encoding = Encoding::US_ASCII) ?
+                   [encoding, Encoding::ASCII_8BIT] : [encoding]
+  end
+
+  def matches?(actual)
+    @actual = actual = actual.encoding
+    @encodings.include?(actual)
+  end
+
+  def failure_message
+    ["Expected #{@actual} to be #{@encodings.join(' or ')}"]
+  end
+
+  def negative_failure_message
+    ["Expected #{@actual} not to be #{@encodings.join(' or ')}"]
+  end
+end
+
+String.__send__(:define_method, :be_locale_env) do |expected = 'locale'|
+  locale_env_matcher.new(expected)
+end
diff --git a/spec/ruby/core/env/to_a_spec.rb b/spec/ruby/core/env/to_a_spec.rb
index ed290a48a5..2b1649281f 100644
--- a/spec/ruby/core/env/to_a_spec.rb
+++ b/spec/ruby/core/env/to_a_spec.rb
@@ -1,19 +1,21 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 
 describe "ENV.to_a" do
 
   it "returns the ENV as an array" do
-    ENV["foo"] = "bar"
     a = ENV.to_a
     a.is_a?(Array).should == true
-    a.find { |e| e.first == "foo" }.should == ["foo", "bar"]
-    ENV.delete "foo"
+    a.size.should == ENV.size
+    a.each { |k,v| ENV[k].should == v }
+
+    a.first.should.is_a?(Array)
+    a.first.size.should == 2
   end
 
   it "returns the entries in the locale encoding" do
     ENV.to_a.each do |key, value|
-      key.encoding.should == Encoding.find('locale')
-      value.encoding.should == Encoding.find('locale')
+      key.should.be_locale_env
+      value.should.be_locale_env
     end
   end
 end
diff --git a/spec/ruby/core/env/to_h_spec.rb b/spec/ruby/core/env/to_h_spec.rb
index 81a17700e9..7e0fef2120 100644
--- a/spec/ruby/core/env/to_h_spec.rb
+++ b/spec/ruby/core/env/to_h_spec.rb
@@ -1,55 +1,70 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 require_relative 'shared/to_hash'
 
 describe "ENV.to_h" do
   it_behaves_like :env_to_hash, :to_h
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      before do
-        @orig_hash = ENV.to_hash
-      end
-
-      after do
-        ENV.replace @orig_hash
-      end
-
-      it "converts [key, value] pairs returned by the block to a hash" do
-        ENV.replace("a" => "b", "c" => "d")
-        ENV.to_h { |k, v| [k, v.upcase] }.should == { 'a' => "B", 'c' => "D" }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          ENV.to_h { |k, v| [k, v.upcase, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          ENV.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          ENV.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        ENV.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          ENV.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    before do
+      @orig_hash = ENV.to_hash
+    end
+
+    after do
+      ENV.replace @orig_hash
+    end
+
+    it "converts [key, value] pairs returned by the block to a hash" do
+      ENV.replace("a" => "b", "c" => "d")
+      ENV.to_h { |k, v| [k, v.upcase] }.should == { 'a' => "B", 'c' => "D" }
+    end
+
+    it "passes to a block each pair's key and value as separate arguments" do
+      ENV.replace("a" => "b", "c" => "d")
+
+      ScratchPad.record []
+      ENV.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [["a", "b"], ["c", "d"]]
+
+      ScratchPad.record []
+      ENV.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [["a", "b"], ["c", "d"]]
+    end
+
+    it "does not require the array elements to be strings" do
+      ENV.replace("a" => "b", "c" => "d")
+      ENV.to_h { |k, v| [k.to_sym, v.to_sym] }.should == { :a => :b, :c => :d }
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        ENV.to_h { |k, v| [k, v.upcase, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        ENV.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        ENV.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      ENV.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        ENV.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/env/to_hash_spec.rb b/spec/ruby/core/env/to_hash_spec.rb
index 4de0e077bb..306572c353 100644
--- a/spec/ruby/core/env/to_hash_spec.rb
+++ b/spec/ruby/core/env/to_hash_spec.rb
@@ -1,4 +1,4 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 require_relative 'shared/to_hash'
 
 describe "ENV.to_hash" do
diff --git a/spec/ruby/core/env/values_at_spec.rb b/spec/ruby/core/env/values_at_spec.rb
index 906d8b01f2..4a733f4ed5 100644
--- a/spec/ruby/core/env/values_at_spec.rb
+++ b/spec/ruby/core/env/values_at_spec.rb
@@ -1,17 +1,38 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 
 describe "ENV.values_at" do
+  before :each do
+    @saved_foo = ENV["foo"]
+    @saved_bar = ENV["bar"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+    ENV["bar"] = @saved_bar
+  end
 
-  it "returns an array of the values referenced by the parameters as keys" do
+  it "returns an array of the values corresponding to the given keys" do
     ENV["foo"] = "oof"
     ENV["bar"] = "rab"
-    ENV.values_at.should == []
     ENV.values_at("bar", "foo").should == ["rab", "oof"]
-    ENV.delete "foo"
-    ENV.delete "bar"
+  end
+
+  it "returns an empty array if no keys specified" do
+    ENV.values_at.should == []
+  end
+
+  it "returns nil for each key that is not a name" do
+    ENV["foo"] = "oof"
+    ENV["bar"] = "rab"
+    ENV.values_at("x", "bar", "y", "foo", "z").should == [nil, "rab", nil, "oof", nil]
   end
 
   it "uses the locale encoding" do
-    ENV.values_at(ENV.keys.first).first.encoding.should == Encoding.find('locale')
+    ENV.values_at(ENV.keys.first).first.encoding.should == ENVSpecs.encoding
+  end
+
+  it "raises TypeError when a key is not coercible to String" do
+    -> { ENV.values_at("foo", Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
   end
 end
diff --git a/spec/ruby/core/env/values_spec.rb b/spec/ruby/core/env/values_spec.rb
index 2e4e69c23b..71bc877d31 100644
--- a/spec/ruby/core/env/values_spec.rb
+++ b/spec/ruby/core/env/values_spec.rb
@@ -1,21 +1,14 @@
-require_relative '../../spec_helper'
+require_relative 'spec_helper'
 
 describe "ENV.values" do
 
   it "returns an array of the values" do
-    orig = ENV.to_hash
-    begin
-      ENV.replace "a" => "b", "c" => "d"
-      a = ENV.values
-      a.sort.should == ["b", "d"]
-    ensure
-      ENV.replace orig
-    end
+    ENV.values.should == ENV.to_hash.values
   end
 
   it "uses the locale encoding" do
     ENV.values.each do |value|
-      value.encoding.should == Encoding.find('locale')
+      value.should.be_locale_env
     end
   end
 end
diff --git a/spec/ruby/core/exception/args_spec.rb b/spec/ruby/core/exception/args_spec.rb
deleted file mode 100644
index 005c2dd198..0000000000
--- a/spec/ruby/core/exception/args_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "NoMethodError#args" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/arguments_spec.rb b/spec/ruby/core/exception/arguments_spec.rb
deleted file mode 100644
index 0b283e9a54..0000000000
--- a/spec/ruby/core/exception/arguments_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ArgumentError" do
-  it "is a subclass of StandardError" do
-    StandardError.should be_ancestor_of(ArgumentError)
-  end
-
-  it "gives its own class name as message if it has no message" do
-    ArgumentError.new.message.should == "ArgumentError"
-  end
-end
diff --git a/spec/ruby/core/exception/backtrace_locations_spec.rb b/spec/ruby/core/exception/backtrace_locations_spec.rb
index 86eb9d3413..62eab8a0f3 100644
--- a/spec/ruby/core/exception/backtrace_locations_spec.rb
+++ b/spec/ruby/core/exception/backtrace_locations_spec.rb
@@ -7,15 +7,15 @@ describe "Exception#backtrace_locations" do
   end
 
   it "returns nil if no backtrace was set" do
-    Exception.new.backtrace_locations.should be_nil
+    Exception.new.backtrace_locations.should == nil
   end
 
   it "returns an Array" do
-    @backtrace.should be_an_instance_of(Array)
+    @backtrace.should.instance_of?(Array)
   end
 
   it "sets each element to a Thread::Backtrace::Location" do
-    @backtrace.each {|l| l.should be_an_instance_of(Thread::Backtrace::Location)}
+    @backtrace.each {|l| l.should.instance_of?(Thread::Backtrace::Location)}
   end
 
   it "produces a backtrace for an exception captured using $!" do
diff --git a/spec/ruby/core/exception/backtrace_spec.rb b/spec/ruby/core/exception/backtrace_spec.rb
index 5e140f8d9b..a4a8272030 100644
--- a/spec/ruby/core/exception/backtrace_spec.rb
+++ b/spec/ruby/core/exception/backtrace_spec.rb
@@ -7,15 +7,15 @@ describe "Exception#backtrace" do
   end
 
   it "returns nil if no backtrace was set" do
-    Exception.new.backtrace.should be_nil
+    Exception.new.backtrace.should == nil
   end
 
   it "returns an Array" do
-    @backtrace.should be_an_instance_of(Array)
+    @backtrace.should.instance_of?(Array)
   end
 
   it "sets each element to a String" do
-    @backtrace.each {|l| l.should be_an_instance_of(String)}
+    @backtrace.each {|l| l.should.instance_of?(String)}
   end
 
   it "includes the filename of the location where self raised in the first element" do
@@ -27,7 +27,7 @@ describe "Exception#backtrace" do
   end
 
   it "includes the name of the method from where self raised in the first element" do
-    @backtrace.first.should =~ /in `backtrace'/
+    @backtrace.first.should =~ /in [`'](?:ExceptionSpecs::Backtrace\.)?backtrace'/
   end
 
   it "includes the filename of the location immediately prior to where self raised in the second element" do
@@ -38,16 +38,29 @@ describe "Exception#backtrace" do
     @backtrace[1].should =~ /:6(:in )?/
   end
 
-  it "contains lines of the same format for each prior position in the stack" do
-    @backtrace[2..-1].each do |line|
-      # This regexp is deliberately imprecise to account for the need to abstract out
-      # the paths of the included mspec files and the desire to avoid specifying in any
-      # detail what the in `...' portion looks like.
-      line.should =~ /^[^ ]+\:\d+(:in `[^`]+')?$/
+  ruby_version_is ""..."3.4" do
+    it "contains lines of the same format for each prior position in the stack" do
+      @backtrace[2..-1].each do |line|
+        # This regexp is deliberately imprecise to account for the need to abstract out
+        # the paths of the included mspec files and the desire to avoid specifying in any
+        # detail what the in `...' portion looks like.
+        line.should =~ /^.+:\d+:in `[^`]+'$/
+      end
     end
   end
 
-  it "produces a backtrace for an exception captured using $!" do
+  ruby_version_is "3.4" do
+    it "contains lines of the same format for each prior position in the stack" do
+      @backtrace[2..-1].each do |line|
+        # This regexp is deliberately imprecise to account for the need to abstract out
+        # the paths of the included mspec files and the desire to avoid specifying in any
+        # detail what the in '...' portion looks like.
+        line.should =~ /^.+:\d+:in '[^`]+'$/
+      end
+    end
+  end
+
+  it "captures the backtrace for an exception into $!" do
     exception = begin
       raise
     rescue RuntimeError
@@ -57,6 +70,16 @@ describe "Exception#backtrace" do
     exception.backtrace.first.should =~ /backtrace_spec/
   end
 
+  it "captures the backtrace for an exception into $@" do
+    backtrace = begin
+      raise
+    rescue RuntimeError
+      $@
+    end
+
+    backtrace.first.should =~ /backtrace_spec/
+  end
+
   it "returns an Array that can be updated" do
     begin
       raise
@@ -71,13 +94,13 @@ describe "Exception#backtrace" do
       raise
     rescue RuntimeError => err
       bt = err.backtrace
-      err.dup.backtrace.should equal(bt)
+      err.dup.backtrace.should.equal?(bt)
 
       new_bt = ['hi']
       err.set_backtrace new_bt
 
       err.backtrace.should == new_bt
-      err.dup.backtrace.should equal(new_bt)
+      err.dup.backtrace.should.equal?(new_bt)
     end
   end
 end
diff --git a/spec/ruby/core/exception/case_compare_spec.rb b/spec/ruby/core/exception/case_compare_spec.rb
index a4c9eaa6bf..5fd11ae741 100644
--- a/spec/ruby/core/exception/case_compare_spec.rb
+++ b/spec/ruby/core/exception/case_compare_spec.rb
@@ -1,5 +1,37 @@
 require_relative '../../spec_helper'
 
 describe "SystemCallError.===" do
-  it "needs to be reviewed for spec completeness"
+  before :all do
+    @example_errno_class = Errno::EINVAL
+    @example_errno = @example_errno_class::Errno
+  end
+
+  it "returns true for an instance of the same class" do
+    Errno::EINVAL.should === Errno::EINVAL.new
+  end
+
+  it "returns true if errnos same" do
+    e = SystemCallError.new('foo', @example_errno)
+    @example_errno_class.===(e).should == true
+  end
+
+  it "returns false if errnos different" do
+    e = SystemCallError.new('foo', @example_errno + 1)
+    @example_errno_class.===(e).should == false
+  end
+
+  it "returns false if arg is not kind of SystemCallError" do
+    e = Object.new
+    @example_errno_class.===(e).should == false
+  end
+
+  it "returns true if receiver is generic and arg is kind of SystemCallError" do
+    e = SystemCallError.new('foo', @example_errno)
+    SystemCallError.===(e).should == true
+  end
+
+  it "returns false if receiver is generic and arg is not kind of SystemCallError" do
+    e = Object.new
+    SystemCallError.===(e).should == false
+  end
 end
diff --git a/spec/ruby/core/exception/cause_spec.rb b/spec/ruby/core/exception/cause_spec.rb
index cf4aaeb188..cfc15bdda3 100644
--- a/spec/ruby/core/exception/cause_spec.rb
+++ b/spec/ruby/core/exception/cause_spec.rb
@@ -4,53 +4,35 @@ describe "Exception#cause" do
   it "returns the active exception when an exception is raised" do
     begin
       raise Exception, "the cause"
-    rescue Exception
-      begin
+    rescue Exception => cause
+      -> {
         raise RuntimeError, "the consequence"
-      rescue RuntimeError => e
-        e.should be_an_instance_of(RuntimeError)
-        e.message.should == "the consequence"
-
-        e.cause.should be_an_instance_of(Exception)
-        e.cause.message.should == "the cause"
-      end
+      }.should.raise(RuntimeError, "the consequence", cause:)
     end
   end
 
   it "is set for user errors caused by internal errors" do
-    -> {
-      begin
-        1 / 0
-      rescue
-        raise "foo"
-      end
-    }.should raise_error(RuntimeError) { |e|
-      e.cause.should be_kind_of(ZeroDivisionError)
-    }
+    begin
+      1 / 0
+    rescue => cause
+      -> { raise "foo" }.should.raise(RuntimeError, cause:)
+    end
   end
 
   it "is set for internal errors caused by user errors" do
     cause = RuntimeError.new "cause"
-    -> {
-      begin
-        raise cause
-      rescue
-        1 / 0
-      end
-    }.should raise_error(ZeroDivisionError) { |e|
-      e.cause.should equal(cause)
-    }
+    begin
+      raise cause
+    rescue
+      -> { 1 / 0 }.should.raise(ZeroDivisionError, cause:)
+    end
   end
 
   it "is not set to the exception itself when it is re-raised" do
-    -> {
-      begin
-        raise RuntimeError
-      rescue RuntimeError => e
-        raise e
-      end
-    }.should raise_error(RuntimeError) { |e|
-      e.cause.should == nil
-    }
+    begin
+      raise RuntimeError
+    rescue RuntimeError => e
+      -> { raise e }.should.raise(RuntimeError, cause: nil)
+    end
   end
 end
diff --git a/spec/ruby/core/exception/destination_encoding_name_spec.rb b/spec/ruby/core/exception/destination_encoding_name_spec.rb
deleted file mode 100644
index b6ffff8c9c..0000000000
--- a/spec/ruby/core/exception/destination_encoding_name_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::UndefinedConversionError#destination_encoding_name" do
-  it "needs to be reviewed for spec completeness"
-end
-
-describe "Encoding::InvalidByteSequenceError#destination_encoding_name" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/destination_encoding_spec.rb b/spec/ruby/core/exception/destination_encoding_spec.rb
deleted file mode 100644
index c3ad0342a1..0000000000
--- a/spec/ruby/core/exception/destination_encoding_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::UndefinedConversionError#destination_encoding" do
-  it "needs to be reviewed for spec completeness"
-end
-
-describe "Encoding::InvalidByteSequenceError#destination_encoding" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/detailed_message_spec.rb b/spec/ruby/core/exception/detailed_message_spec.rb
new file mode 100644
index 0000000000..9df164a1cf
--- /dev/null
+++ b/spec/ruby/core/exception/detailed_message_spec.rb
@@ -0,0 +1,50 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+
+describe "Exception#detailed_message" do
+  it "returns decorated message" do
+    RuntimeError.new("new error").detailed_message.should == "new error (RuntimeError)"
+  end
+
+  it "is called by #full_message to allow message customization" do
+    exception = Exception.new("new error")
+    def exception.detailed_message(**)
+      "<prefix>#{message}<suffix>"
+    end
+    exception.full_message(highlight: false).should.include? "<prefix>new error<suffix>"
+  end
+
+  it "returns just a message if exception class is anonymous" do
+    Class.new(RuntimeError).new("message").detailed_message.should == "message"
+  end
+
+  it "returns 'unhandled exception' for an instance of RuntimeError with empty message" do
+    RuntimeError.new("").detailed_message.should == "unhandled exception"
+  end
+
+  it "returns just class name for an instance other than RuntimeError with empty message" do
+    DetailedMessageSpec::C.new("").detailed_message.should == "DetailedMessageSpec::C"
+    StandardError.new("").detailed_message.should == "StandardError"
+  end
+
+  it "returns a generated class name for an instance of RuntimeError anonymous subclass with empty message" do
+    klass = Class.new(RuntimeError)
+    klass.new("").detailed_message.should =~ /\A#<Class:0x\h+>\z/
+  end
+
+  it "accepts highlight keyword argument and adds escape control sequences" do
+    RuntimeError.new("new error").detailed_message(highlight: true).should == "\e[1mnew error (\e[1;4mRuntimeError\e[m\e[1m)\e[m"
+  end
+
+  it "accepts highlight keyword argument and adds escape control sequences for an instance of RuntimeError with empty message" do
+    RuntimeError.new("").detailed_message(highlight: true).should == "\e[1;4munhandled exception\e[m"
+  end
+
+  it "accepts highlight keyword argument and adds escape control sequences for an instance other than RuntimeError with empty message" do
+    StandardError.new("").detailed_message(highlight: true).should == "\e[1;4mStandardError\e[m"
+  end
+
+  it "allows and ignores other keyword arguments" do
+    RuntimeError.new("new error").detailed_message(foo: true).should == "new error (RuntimeError)"
+  end
+end
diff --git a/spec/ruby/core/exception/dup_spec.rb b/spec/ruby/core/exception/dup_spec.rb
index edd54bfb37..b53ad79bf3 100644
--- a/spec/ruby/core/exception/dup_spec.rb
+++ b/spec/ruby/core/exception/dup_spec.rb
@@ -20,7 +20,7 @@ describe "Exception#dup" do
   it "does not copy singleton methods" do
     def @obj.special() :the_one end
     dup = @obj.dup
-    -> { dup.special }.should raise_error(NameError)
+    -> { dup.special }.should.raise(NameError)
   end
 
   it "does not copy modules included in the singleton class" do
@@ -29,7 +29,7 @@ describe "Exception#dup" do
     end
 
     dup = @obj.dup
-    -> { dup.repr }.should raise_error(NameError)
+    -> { dup.repr }.should.raise(NameError)
   end
 
   it "does not copy constants defined in the singleton class" do
@@ -38,7 +38,7 @@ describe "Exception#dup" do
     end
 
     dup = @obj.dup
-    -> { class << dup; CLONE; end }.should raise_error(NameError)
+    -> { class << dup; CLONE; end }.should.raise(NameError)
   end
 
   it "does copy the message" do
@@ -61,13 +61,13 @@ describe "Exception#dup" do
 
   it "does copy the cause" do
     begin
-      raise StandardError, "the cause"
+      raise StandardError
     rescue StandardError => cause
       begin
-        raise RuntimeError, "the consequence"
+        raise RuntimeError
       rescue RuntimeError => e
-        e.cause.should equal(cause)
-        e.dup.cause.should equal(cause)
+        e.cause.should.equal?(cause)
+        e.dup.cause.should.equal?(cause)
       end
     end
   end
diff --git a/spec/ruby/core/exception/equal_value_spec.rb b/spec/ruby/core/exception/equal_value_spec.rb
index 7f2065511a..b76b3bcd4a 100644
--- a/spec/ruby/core/exception/equal_value_spec.rb
+++ b/spec/ruby/core/exception/equal_value_spec.rb
@@ -22,19 +22,19 @@ describe "Exception#==" do
 
   it "returns true if both exceptions have the same class, the same message, and the same backtrace" do
     one = TypeError.new("message")
-    one.set_backtrace [File.dirname(__FILE__)]
+    one.set_backtrace [__dir__]
     two = TypeError.new("message")
-    two.set_backtrace [File.dirname(__FILE__)]
+    two.set_backtrace [__dir__]
     one.should == two
   end
 
   it "returns false if the two exceptions inherit from Exception but have different classes" do
     one = RuntimeError.new("message")
-    one.set_backtrace [File.dirname(__FILE__)]
-    one.should be_kind_of(Exception)
+    one.set_backtrace [__dir__]
+    one.should.is_a?(Exception)
     two = TypeError.new("message")
-    two.set_backtrace [File.dirname(__FILE__)]
-    two.should be_kind_of(Exception)
+    two.set_backtrace [__dir__]
+    two.should.is_a?(Exception)
     one.should_not == two
   end
 
@@ -52,7 +52,7 @@ describe "Exception#==" do
 
   it "returns false if the two exceptions differ only in their backtrace" do
     one = RuntimeError.new("message")
-    one.set_backtrace [File.dirname(__FILE__)]
+    one.set_backtrace [__dir__]
     two = RuntimeError.new("message")
     two.set_backtrace nil
     one.should_not == two
@@ -60,9 +60,9 @@ describe "Exception#==" do
 
   it "returns false if the two exceptions differ only in their message" do
     one = RuntimeError.new("message")
-    one.set_backtrace [File.dirname(__FILE__)]
+    one.set_backtrace [__dir__]
     two = RuntimeError.new("message2")
-    two.set_backtrace [File.dirname(__FILE__)]
+    two.set_backtrace [__dir__]
     one.should_not == two
   end
 end
diff --git a/spec/ruby/core/exception/errno_spec.rb b/spec/ruby/core/exception/errno_spec.rb
index 9e0bf0086a..36beae9976 100644
--- a/spec/ruby/core/exception/errno_spec.rb
+++ b/spec/ruby/core/exception/errno_spec.rb
@@ -1,28 +1,24 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
-describe "SystemCallError#errno" do
-  it "needs to be reviewed for spec completeness"
-end
-
 describe "Errno::EINVAL.new" do
   it "can be called with no arguments" do
     exc = Errno::EINVAL.new
-    exc.should be_an_instance_of(Errno::EINVAL)
+    exc.should.instance_of?(Errno::EINVAL)
     exc.errno.should == Errno::EINVAL::Errno
     exc.message.should == "Invalid argument"
   end
 
   it "accepts an optional custom message" do
     exc = Errno::EINVAL.new('custom message')
-    exc.should be_an_instance_of(Errno::EINVAL)
+    exc.should.instance_of?(Errno::EINVAL)
     exc.errno.should == Errno::EINVAL::Errno
     exc.message.should == "Invalid argument - custom message"
   end
 
   it "accepts an optional custom message and location" do
     exc = Errno::EINVAL.new('custom message', 'location')
-    exc.should be_an_instance_of(Errno::EINVAL)
+    exc.should.instance_of?(Errno::EINVAL)
     exc.errno.should == Errno::EINVAL::Errno
     exc.message.should == "Invalid argument @ location - custom message"
   end
@@ -32,7 +28,9 @@ describe "Errno::EMFILE" do
   it "can be subclassed" do
     ExceptionSpecs::EMFILESub = Class.new(Errno::EMFILE)
     exc = ExceptionSpecs::EMFILESub.new
-    exc.should be_an_instance_of(ExceptionSpecs::EMFILESub)
+    exc.should.instance_of?(ExceptionSpecs::EMFILESub)
+  ensure
+    ExceptionSpecs.send(:remove_const, :EMFILESub)
   end
 end
 
@@ -46,3 +44,26 @@ describe "Errno::EAGAIN" do
     end
   end
 end
+
+describe "Errno::ENOTSUP" do
+  it "is defined" do
+    Errno.should.const_defined?(:ENOTSUP, false)
+  end
+
+  it "is the same class as Errno::EOPNOTSUPP if they represent the same errno value" do
+    if Errno::ENOTSUP::Errno == Errno::EOPNOTSUPP::Errno
+      Errno::ENOTSUP.should == Errno::EOPNOTSUPP
+    else
+      Errno::ENOTSUP.should_not == Errno::EOPNOTSUPP
+    end
+  end
+end
+
+describe "Errno::ENOENT" do
+  it "lets subclasses inherit the default error message" do
+    c = Class.new(Errno::ENOENT)
+    raise c, "custom message"
+  rescue => e
+    e.message.should == "No such file or directory - custom message"
+  end
+end
diff --git a/spec/ruby/core/exception/error_bytes_spec.rb b/spec/ruby/core/exception/error_bytes_spec.rb
deleted file mode 100644
index 2a95bcfdf4..0000000000
--- a/spec/ruby/core/exception/error_bytes_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::InvalidByteSequenceError#error_bytes" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/error_char_spec.rb b/spec/ruby/core/exception/error_char_spec.rb
deleted file mode 100644
index c0256af03a..0000000000
--- a/spec/ruby/core/exception/error_char_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::UndefinedConversionError#error_char" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/exception_spec.rb b/spec/ruby/core/exception/exception_spec.rb
index 3a01366920..f5424cdabd 100644
--- a/spec/ruby/core/exception/exception_spec.rb
+++ b/spec/ruby/core/exception/exception_spec.rb
@@ -6,48 +6,6 @@ describe "Exception.exception" do
   it_behaves_like :exception_new, :exception
 end
 
-describe "Exception" do
-  it "is a Class" do
-    Exception.should be_kind_of(Class)
-  end
-
-  it "is a superclass of NoMemoryError" do
-    Exception.should be_ancestor_of(NoMemoryError)
-  end
-
-  it "is a superclass of ScriptError" do
-    Exception.should be_ancestor_of(ScriptError)
-  end
-
-  it "is a superclass of SignalException" do
-    Exception.should be_ancestor_of(SignalException)
-  end
-
-  it "is a superclass of Interrupt" do
-    SignalException.should be_ancestor_of(Interrupt)
-  end
-
-  it "is a superclass of StandardError" do
-    Exception.should be_ancestor_of(StandardError)
-  end
-
-  it "is a superclass of SystemExit" do
-    Exception.should be_ancestor_of(SystemExit)
-  end
-
-  it "is a superclass of SystemStackError" do
-    Exception.should be_ancestor_of(SystemStackError)
-  end
-
-  it "is a superclass of SecurityError" do
-    Exception.should be_ancestor_of(SecurityError)
-  end
-
-  it "is a superclass of EncodingError" do
-    Exception.should be_ancestor_of(EncodingError)
-  end
-end
-
 describe "Exception#exception" do
   it "returns self when passed no argument" do
     e = RuntimeError.new
@@ -62,7 +20,7 @@ describe "Exception#exception" do
   it "returns an exception of the same class as self with the message given as argument" do
     e = RuntimeError.new
     e2 = e.exception("message")
-    e2.should be_an_instance_of(RuntimeError)
+    e2.should.instance_of?(RuntimeError)
     e2.message.should == "message"
   end
 
@@ -82,6 +40,18 @@ describe "Exception#exception" do
     raised_second.should == caught_second
   end
 
+  it "captures an exception into $!" do
+    exception = begin
+      raise
+    rescue RuntimeError
+      $!
+    end
+
+    exception.class.should == RuntimeError
+    exception.message.should == ""
+    exception.backtrace.first.should =~ /exception_spec/
+  end
+
   class CustomArgumentError < StandardError
     attr_reader :val
     def initialize(val)
@@ -92,7 +62,7 @@ describe "Exception#exception" do
   it "returns an exception of the same class as self with the message given as argument, but without reinitializing" do
     e = CustomArgumentError.new(:boom)
     e2 = e.exception("message")
-    e2.should be_an_instance_of(CustomArgumentError)
+    e2.should.instance_of?(CustomArgumentError)
     e2.val.should == :boom
     e2.message.should == "message"
   end
diff --git a/spec/ruby/core/exception/exit_value_spec.rb b/spec/ruby/core/exception/exit_value_spec.rb
index 43de56af8b..bb6cff1831 100644
--- a/spec/ruby/core/exception/exit_value_spec.rb
+++ b/spec/ruby/core/exception/exit_value_spec.rb
@@ -1,5 +1,13 @@
 require_relative '../../spec_helper'
 
 describe "LocalJumpError#exit_value" do
-  it "needs to be reviewed for spec completeness"
+  def get_me_a_return
+    Proc.new { return 42 }
+  end
+
+  it "returns the value given to return" do
+    -> { get_me_a_return.call }.should.raise(LocalJumpError) { |e|
+      e.exit_value.should == 42
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/fixtures/common.rb b/spec/ruby/core/exception/fixtures/common.rb
index 0ffb3ed855..3d8a3c3430 100644
--- a/spec/ruby/core/exception/fixtures/common.rb
+++ b/spec/ruby/core/exception/fixtures/common.rb
@@ -84,6 +84,9 @@ module NoMethodErrorSpecs
 
   class InstanceException < Exception
   end
+
+  class AClass; end
+  module AModule; end
 end
 
 class NameErrorSpecs
@@ -93,3 +96,7 @@ class NameErrorSpecs
     end
   end
 end
+
+module DetailedMessageSpec
+  C = Class.new(RuntimeError)
+end
diff --git a/spec/ruby/core/exception/fixtures/syntax_error.rb b/spec/ruby/core/exception/fixtures/syntax_error.rb
new file mode 100644
index 0000000000..ccec62f7a1
--- /dev/null
+++ b/spec/ruby/core/exception/fixtures/syntax_error.rb
@@ -0,0 +1,3 @@
+# rubocop:disable Lint/Syntax
+1+1=2
+# rubocop:enable Lint/Syntax
diff --git a/spec/ruby/core/exception/fixtures/thread_fiber_ensure.rb b/spec/ruby/core/exception/fixtures/thread_fiber_ensure.rb
new file mode 100644
index 0000000000..c109ec6247
--- /dev/null
+++ b/spec/ruby/core/exception/fixtures/thread_fiber_ensure.rb
@@ -0,0 +1,22 @@
+ready = false
+t = Thread.new do
+  f = Fiber.new do
+    begin
+      Fiber.yield
+    ensure
+      STDERR.puts "suspended fiber ensure"
+    end
+  end
+  f.resume
+
+  begin
+    ready = true
+    sleep
+  ensure
+    STDERR.puts "current fiber ensure"
+  end
+end
+
+Thread.pass until ready && t.stop?
+
+# let the program end, it's the same as #exit or an exception for this behavior
diff --git a/spec/ruby/core/exception/fixtures/thread_fiber_ensure_non_root_fiber.rb b/spec/ruby/core/exception/fixtures/thread_fiber_ensure_non_root_fiber.rb
new file mode 100644
index 0000000000..3364ed06d0
--- /dev/null
+++ b/spec/ruby/core/exception/fixtures/thread_fiber_ensure_non_root_fiber.rb
@@ -0,0 +1,25 @@
+ready = false
+t = Thread.new do
+  f = Fiber.new do
+    begin
+      Fiber.yield
+    ensure
+      STDERR.puts "suspended fiber ensure"
+    end
+  end
+  f.resume
+
+  f2 = Fiber.new do
+    begin
+      ready = true
+      sleep
+    ensure
+      STDERR.puts "current fiber ensure"
+    end
+  end
+  f2.resume
+end
+
+Thread.pass until ready && t.stop?
+
+# let the program end, it's the same as #exit or an exception for this behavior
diff --git a/spec/ruby/core/exception/frozen_error_spec.rb b/spec/ruby/core/exception/frozen_error_spec.rb
index 7b356253c4..a28f524b54 100644
--- a/spec/ruby/core/exception/frozen_error_spec.rb
+++ b/spec/ruby/core/exception/frozen_error_spec.rb
@@ -1,34 +1,54 @@
 require_relative '../../spec_helper'
 
-describe "FrozenError" do
-  ruby_version_is "2.5" do
-    it "is a subclass of RuntimeError" do
-      RuntimeError.should be_ancestor_of(FrozenError)
-    end
+describe "FrozenError.new" do
+  it "should take optional receiver argument" do
+    o = Object.new
+    FrozenError.new("msg", receiver: o).receiver.should.equal?(o)
   end
 end
 
-describe "FrozenError.new" do
-  ruby_version_is "2.7" do
-    it "should take optional receiver argument" do
-      o = Object.new
-      FrozenError.new("msg", o).receiver.should equal(o)
+describe "FrozenError#receiver" do
+  it "should return frozen object that modification was attempted on" do
+    o = Object.new.freeze
+    begin
+      def o.x; end
+    rescue => e
+      e.should.is_a?(FrozenError)
+      e.receiver.should.equal?(o)
+    else
+      raise
     end
   end
 end
 
-describe "FrozenError#receiver" do
-  ruby_version_is "2.7" do
-    it "should return frozen object that modification was attempted on" do
-      o = Object.new.freeze
-      begin
-        def o.x; end
-      rescue => e
-        e.should be_kind_of(FrozenError)
-        e.receiver.should equal(o)
-      else
-        raise
-      end
+describe "FrozenError#message" do
+  it "includes a receiver" do
+    object = Object.new
+    object.freeze
+
+    msg_class = ruby_version_is("4.0") ? "Object" : "object"
+
+    -> {
+      def object.x; end
+    }.should.raise(FrozenError, "can't modify frozen #{msg_class}: #{object}")
+
+    object = [].freeze
+    -> { object << nil }.should.raise(FrozenError, "can't modify frozen Array: []")
+  end
+end
+
+describe "Modifying a frozen object" do
+  context "#inspect is redefined and modifies the object" do
+    it "returns ... instead of String representation of object" do
+      object = Object.new
+      def object.inspect; @a = 1 end
+      def object.modify; @a = 2 end
+
+      object.freeze
+
+      # CRuby's message contains multiple whitespaces before '...'.
+      # So handle both multiple and single whitespace.
+      -> { object.modify }.should.raise(FrozenError, /can't modify frozen .*?: \s*.../)
     end
   end
 end
diff --git a/spec/ruby/core/exception/full_message_spec.rb b/spec/ruby/core/exception/full_message_spec.rb
index 3df2d47f61..5a5e0a2b3a 100644
--- a/spec/ruby/core/exception/full_message_spec.rb
+++ b/spec/ruby/core/exception/full_message_spec.rb
@@ -1,94 +1,226 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  describe "Exception#full_message" do
-    it "returns formatted string of exception using the same format that is used to print an uncaught exceptions to stderr" do
-      e = RuntimeError.new("Some runtime error")
-      e.set_backtrace(["a.rb:1", "b.rb:2"])
-
-      full_message = e.full_message
-      full_message.should include "RuntimeError"
-      full_message.should include "Some runtime error"
-      full_message.should include "a.rb:1"
-      full_message.should include "b.rb:2"
-    end
+describe "Exception#full_message" do
+  it "returns formatted string of exception using the same format that is used to print an uncaught exceptions to stderr" do
+    e = RuntimeError.new("Some runtime error")
+    e.set_backtrace(["a.rb:1", "b.rb:2"])
+
+    full_message = e.full_message
+    full_message.should.include? "RuntimeError"
+    full_message.should.include? "Some runtime error"
+    full_message.should.include? "a.rb:1"
+    full_message.should.include? "b.rb:2"
+  end
+
+  it "supports :highlight option and adds escape sequences to highlight some strings" do
+    e = RuntimeError.new("Some runtime error")
+
+    full_message = e.full_message(highlight: true, order: :top).lines
+    full_message[0].should.end_with? "\e[1mSome runtime error (\e[1;4mRuntimeError\e[m\e[1m)\e[m\n"
+
+    full_message = e.full_message(highlight: true, order: :bottom).lines
+    full_message[0].should == "\e[1mTraceback\e[m (most recent call last):\n"
+    full_message[-1].should.end_with? "\e[1mSome runtime error (\e[1;4mRuntimeError\e[m\e[1m)\e[m\n"
+
+    full_message = e.full_message(highlight: false, order: :top).lines
+    full_message[0].should.end_with? "Some runtime error (RuntimeError)\n"
+
+    full_message = e.full_message(highlight: false, order: :bottom).lines
+    full_message[0].should == "Traceback (most recent call last):\n"
+    full_message[-1].should.end_with? "Some runtime error (RuntimeError)\n"
+  end
+
+  it "supports :order option and places the error message and the backtrace at the top or the bottom" do
+    e = RuntimeError.new("Some runtime error")
+    e.set_backtrace(["a.rb:1", "b.rb:2"])
+
+    e.full_message(order: :top,    highlight: false).should =~ /a.rb:1.*b.rb:2/m
+    e.full_message(order: :bottom, highlight: false).should =~ /b.rb:2.*a.rb:1/m
+  end
 
-    ruby_version_is "2.5.1" do
-      it "supports :highlight option and adds escape sequences to highlight some strings" do
-        e = RuntimeError.new("Some runtime error")
+  it "shows the caller if the exception has no backtrace" do
+    e = RuntimeError.new("Some runtime error")
+    e.backtrace.should == nil
+    full_message = e.full_message(highlight: false, order: :top).lines
+    full_message[0].should.start_with?("#{__FILE__}:#{__LINE__-1}:in ")
+    full_message[0].should.end_with?("': Some runtime error (RuntimeError)\n")
+  end
 
-        full_message = e.full_message(highlight: true, order: :bottom)
-        full_message.should include "\e[1mTraceback\e[m (most recent call last)"
-        full_message.should include "\e[1mSome runtime error (\e[1;4mRuntimeError\e[m\e[1m)"
+  describe "includes details about whether an exception was handled" do
+    describe "RuntimeError" do
+      it "should report as unhandled if message is empty" do
+        err = RuntimeError.new("")
 
-        full_message = e.full_message(highlight: false, order: :bottom)
-        full_message.should include "Traceback (most recent call last)"
-        full_message.should include "Some runtime error (RuntimeError)"
+        err.full_message.should =~ /unhandled exception/
+        err.full_message(highlight: true).should =~ /unhandled exception/
+        err.full_message(highlight: false).should =~ /unhandled exception/
       end
 
-      it "supports :order option and places the error message and the backtrace at the top or the bottom" do
-        e = RuntimeError.new("Some runtime error")
-        e.set_backtrace(["a.rb:1", "b.rb:2"])
+      it "should not report as unhandled if the message is not empty" do
+        err = RuntimeError.new("non-empty")
 
-        e.full_message(order: :top,    highlight: false).should =~ /a.rb:1.*b.rb:2/m
-        e.full_message(order: :bottom, highlight: false).should =~ /b.rb:2.*a.rb:1/m
+        err.full_message.should !~ /unhandled exception/
+        err.full_message(highlight: true).should !~ /unhandled exception/
+        err.full_message(highlight: false).should !~ /unhandled exception/
       end
 
-      it "shows the caller if the exception has no backtrace" do
-        e = RuntimeError.new("Some runtime error")
-        e.backtrace.should == nil
-        full_message = e.full_message(highlight: false, order: :top)
-        full_message.should include("#{__FILE__}:#{__LINE__-1}:in `")
-        full_message.should include("': Some runtime error (RuntimeError)\n")
+      it "should not report as unhandled if the message is nil" do
+        err = RuntimeError.new(nil)
+
+        err.full_message.should !~ /unhandled exception/
+        err.full_message(highlight: true).should !~ /unhandled exception/
+        err.full_message(highlight: false).should !~ /unhandled exception/
       end
 
-      it "shows the exception class at the end of the first line of the message when the message contains multiple lines" do
-        begin
-          line = __LINE__; raise "first line\nsecond line"
-        rescue => e
-          full_message = e.full_message(highlight: false, order: :top).lines
-          full_message[0].should include("#{__FILE__}:#{line}:in `")
-          full_message[0].should include(": first line (RuntimeError)\n")
-          full_message[1].should == "second line\n"
-        end
+      it "should not report as unhandled if the message is not specified" do
+        err = RuntimeError.new()
+
+        err.full_message.should !~ /unhandled exception/
+        err.full_message(highlight: true).should !~ /unhandled exception/
+        err.full_message(highlight: false).should !~ /unhandled exception/
+      end
+
+      it "adds escape sequences to highlight some strings if the message is not specified and :highlight option is specified" do
+        e = RuntimeError.new("")
+
+        full_message = e.full_message(highlight: true, order: :top).lines
+        full_message[0].should.end_with? "\e[1;4munhandled exception\e[m\n"
+
+        full_message = e.full_message(highlight: true, order: :bottom).lines
+        full_message[0].should == "\e[1mTraceback\e[m (most recent call last):\n"
+        full_message[-1].should.end_with? "\e[1;4munhandled exception\e[m\n"
+
+        full_message = e.full_message(highlight: false, order: :top).lines
+        full_message[0].should.end_with? "unhandled exception\n"
+
+        full_message = e.full_message(highlight: false, order: :bottom).lines
+        full_message[0].should == "Traceback (most recent call last):\n"
+        full_message[-1].should.end_with? "unhandled exception\n"
       end
     end
 
-    ruby_version_is "2.6" do
-      it "contains cause of exception" do
-        begin
-          begin
-            raise 'the cause'
-          rescue
-            raise 'main exception'
-          end
-        rescue => e
-          exception = e
-        end
+    describe "generic Error" do
+      it "should not report as unhandled in any event" do
+        StandardError.new("").full_message.should !~ /unhandled exception/
+        StandardError.new("non-empty").full_message.should !~ /unhandled exception/
+      end
+    end
+  end
+
+  it "shows the exception class at the end of the first line of the message when the message contains multiple lines" do
+    begin
+      line = __LINE__; raise "first line\nsecond line"
+    rescue => e
+      full_message = e.full_message(highlight: false, order: :top).lines
+      full_message[0].should.start_with?("#{__FILE__}:#{line}:in ")
+      full_message[0].should.end_with?(": first line (RuntimeError)\n")
+      full_message[1].should == "second line\n"
+    end
+  end
 
-        exception.full_message.should include "main exception"
-        exception.full_message.should include "the cause"
+  it "highlights the entire message when the message contains multiple lines" do
+    begin
+      line = __LINE__; raise "first line\nsecond line\nthird line"
+    rescue => e
+      full_message = e.full_message(highlight: true, order: :top).lines
+      full_message[0].should.start_with?("#{__FILE__}:#{line}:in ")
+      full_message[0].should.end_with?(": \e[1mfirst line (\e[1;4mRuntimeError\e[m\e[1m)\e[m\n")
+      full_message[1].should == "\e[1msecond line\e[m\n"
+      full_message[2].should == "\e[1mthird line\e[m\n"
+    end
+  end
+
+  it "contains cause of exception" do
+    begin
+      begin
+        raise 'the cause'
+      rescue
+        raise 'main exception'
       end
+    rescue => e
+      exception = e
+    end
 
-      it 'contains all the chain of exceptions' do
+    exception.full_message.should.include? "main exception"
+    exception.full_message.should.include? "the cause"
+  end
+
+  it 'contains all the chain of exceptions' do
+    begin
+      begin
         begin
-          begin
-            begin
-              raise 'origin exception'
-            rescue
-              raise 'intermediate exception'
-            end
-          rescue
-            raise 'last exception'
-          end
-        rescue => e
-          exception = e
+          raise 'origin exception'
+        rescue
+          raise 'intermediate exception'
         end
-
-        exception.full_message.should include "last exception"
-        exception.full_message.should include "intermediate exception"
-        exception.full_message.should include "origin exception"
+      rescue
+        raise 'last exception'
       end
+    rescue => e
+      exception = e
+    end
+
+    exception.full_message.should.include? "last exception"
+    exception.full_message.should.include? "intermediate exception"
+    exception.full_message.should.include? "origin exception"
+  end
+
+  it "relies on #detailed_message" do
+    e = RuntimeError.new("new error")
+    e.define_singleton_method(:detailed_message) { |**| "DETAILED MESSAGE" }
+
+    e.full_message.lines.first.should =~ /DETAILED MESSAGE/
+  end
+
+  it "passes all its own keyword arguments (with :highlight default value and without :order default value) to #detailed_message" do
+    e = RuntimeError.new("new error")
+    options_passed = nil
+    e.define_singleton_method(:detailed_message) do |**options|
+      options_passed = options
+      "DETAILED MESSAGE"
+    end
+
+    e.full_message(foo: "bar")
+    options_passed.should == { foo: "bar", highlight: Exception.to_tty? }
+  end
+
+  it "converts #detailed_message returned value to String if it isn't a String" do
+    message = Object.new
+    def message.to_str; "DETAILED MESSAGE"; end
+
+    e = RuntimeError.new("new error")
+    e.define_singleton_method(:detailed_message) { |**| message }
+
+    e.full_message.lines.first.should =~ /DETAILED MESSAGE/
+  end
+
+  it "uses class name if #detailed_message returns nil" do
+    e = RuntimeError.new("new error")
+    e.define_singleton_method(:detailed_message) { |**| nil }
+
+    e.full_message(highlight: false).lines.first.should =~ /RuntimeError/
+    e.full_message(highlight: true).lines.first.should =~ /#{Regexp.escape("\e[1;4mRuntimeError\e[m")}/
+  end
+
+  it "uses class name if exception object doesn't respond to #detailed_message" do
+    e = RuntimeError.new("new error")
+    class << e
+      undef :detailed_message
     end
+
+    e.full_message(highlight: false).lines.first.should =~ /RuntimeError/
+    e.full_message(highlight: true).lines.first.should =~ /#{Regexp.escape("\e[1;4mRuntimeError\e[m")}/
+  end
+
+  it "allows cause with empty backtrace" do
+    begin
+      raise RuntimeError.new("Some runtime error"), cause: RuntimeError.new("Some other runtime error")
+    rescue => e
+    end
+
+    full_message = e.full_message
+    full_message.should.include? "RuntimeError"
+    full_message.should.include? "Some runtime error"
+    full_message.should.include? "Some other runtime error"
   end
 end
diff --git a/spec/ruby/core/exception/hierarchy_spec.rb b/spec/ruby/core/exception/hierarchy_spec.rb
new file mode 100644
index 0000000000..6514eb1994
--- /dev/null
+++ b/spec/ruby/core/exception/hierarchy_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../spec_helper'
+
+describe "Exception" do
+  it "has the right class hierarchy" do
+    hierarchy = {
+      Exception => {
+        NoMemoryError => nil,
+        ScriptError => {
+          LoadError => nil,
+          NotImplementedError => nil,
+          SyntaxError => nil,
+        },
+        SecurityError => nil,
+        SignalException => {
+          Interrupt => nil,
+        },
+        StandardError => {
+          ArgumentError => {
+            UncaughtThrowError => nil,
+          },
+          EncodingError => nil,
+          FiberError => nil,
+          IOError => {
+            EOFError => nil,
+          },
+          IndexError => {
+            KeyError => nil,
+            StopIteration => {
+              ClosedQueueError => nil,
+            },
+          },
+          LocalJumpError => nil,
+          NameError => {
+            NoMethodError => nil,
+          },
+          RangeError => {
+            FloatDomainError => nil,
+          },
+          RegexpError => nil,
+          RuntimeError => {
+            FrozenError => nil,
+          },
+          SystemCallError => nil,
+          ThreadError => nil,
+          TypeError => nil,
+          ZeroDivisionError => nil,
+        },
+        SystemExit => nil,
+        SystemStackError => nil,
+      },
+    }
+
+    traverse = -> parent_class, parent_subclass_hash {
+      parent_subclass_hash.each do |child_class, child_subclass_hash|
+        child_class.class.should == Class
+        child_class.superclass.should == parent_class
+        traverse.call(child_class, child_subclass_hash) if child_subclass_hash
+      end
+    }
+    traverse.call(Object, hierarchy)
+  end
+end
diff --git a/spec/ruby/core/exception/incomplete_input_spec.rb b/spec/ruby/core/exception/incomplete_input_spec.rb
deleted file mode 100644
index b033b33f56..0000000000
--- a/spec/ruby/core/exception/incomplete_input_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::InvalidByteSequenceError#incomplete_input?" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/initialize_spec.rb b/spec/ruby/core/exception/initialize_spec.rb
deleted file mode 100644
index e724feaa39..0000000000
--- a/spec/ruby/core/exception/initialize_spec.rb
+++ /dev/null
@@ -1 +0,0 @@
-require_relative '../../spec_helper'
diff --git a/spec/ruby/core/exception/inspect_spec.rb b/spec/ruby/core/exception/inspect_spec.rb
index 519ce574ae..6f380a36c7 100644
--- a/spec/ruby/core/exception/inspect_spec.rb
+++ b/spec/ruby/core/exception/inspect_spec.rb
@@ -6,6 +6,10 @@ describe "Exception#inspect" do
     Exception.new.inspect.should == "#<Exception: Exception>"
   end
 
+  it "keeps message encoding" do
+    Exception.new('å').inspect.should == "#<Exception: å>"
+  end
+
   it "includes #to_s when the result is non-empty" do
     ExceptionSpecs::OverrideToS.new.inspect.should == "#<ExceptionSpecs::OverrideToS: this is from #to_s>"
   end
diff --git a/spec/ruby/core/exception/interrupt_spec.rb b/spec/ruby/core/exception/interrupt_spec.rb
index bc01b7b703..90d261e470 100644
--- a/spec/ruby/core/exception/interrupt_spec.rb
+++ b/spec/ruby/core/exception/interrupt_spec.rb
@@ -1,11 +1,5 @@
 require_relative '../../spec_helper'
 
-describe "Interrupt" do
-  it "is a subclass of SignalException" do
-    Interrupt.superclass.should == SignalException
-  end
-end
-
 describe "Interrupt.new" do
   it "returns an instance of interrupt with no message given" do
     e = Interrupt.new
@@ -35,7 +29,32 @@ describe "rescuing Interrupt" do
       sleep
     rescue Interrupt => e
       e.signo.should == Signal.list["INT"]
-      e.signm.should == ""
+      ["", "Interrupt"].should.include?(e.message)
+    end
+  end
+end
+
+describe "Interrupt" do
+  # This spec is basically the same as above,
+  # but it does not rely on Signal.trap(:INT, :SIG_DFL) which can be tricky
+  it "is raised on the main Thread by the default SIGINT handler" do
+    out = ruby_exe(<<-'RUBY', args: "2>&1")
+    begin
+      Process.kill :INT, Process.pid
+      sleep
+    rescue Interrupt => e
+      puts "Interrupt: #{e.signo}"
+    end
+    RUBY
+    out.should == "Interrupt: #{Signal.list["INT"]}\n"
+  end
+
+  platform_is_not :windows do
+    it "shows the backtrace and has a signaled exit status" do
+      err = IO.popen([*ruby_exe, '-e', 'Process.kill :INT, Process.pid; sleep'], err: [:child, :out], &:read)
+      $?.termsig.should == Signal.list.fetch('INT')
+      err.should.include? ': Interrupt'
+      err.should =~ /from -e:1:in [`']<main>'/
     end
   end
 end
diff --git a/spec/ruby/core/exception/io_error_spec.rb b/spec/ruby/core/exception/io_error_spec.rb
index 8dc10cc6ce..940d5be876 100644
--- a/spec/ruby/core/exception/io_error_spec.rb
+++ b/spec/ruby/core/exception/io_error_spec.rb
@@ -1,22 +1,16 @@
 require_relative '../../spec_helper'
 
-describe "IOError" do
-  it "is a superclass of EOFError" do
-    IOError.should be_ancestor_of(EOFError)
-  end
-end
-
 describe "IO::EAGAINWaitReadable" do
   it "combines Errno::EAGAIN and IO::WaitReadable" do
     IO::EAGAINWaitReadable.superclass.should == Errno::EAGAIN
-    IO::EAGAINWaitReadable.ancestors.should include IO::WaitReadable
+    IO::EAGAINWaitReadable.ancestors.should.include? IO::WaitReadable
   end
 
   it "is the same as IO::EWOULDBLOCKWaitReadable if Errno::EAGAIN is the same as Errno::EWOULDBLOCK" do
     if Errno::EAGAIN.equal? Errno::EWOULDBLOCK
-      IO::EAGAINWaitReadable.should equal IO::EWOULDBLOCKWaitReadable
+      IO::EAGAINWaitReadable.should.equal? IO::EWOULDBLOCKWaitReadable
     else
-      IO::EAGAINWaitReadable.should_not equal IO::EWOULDBLOCKWaitReadable
+      IO::EAGAINWaitReadable.should_not.equal? IO::EWOULDBLOCKWaitReadable
     end
   end
 end
@@ -24,21 +18,21 @@ end
 describe "IO::EWOULDBLOCKWaitReadable" do
   it "combines Errno::EWOULDBLOCK and IO::WaitReadable" do
     IO::EWOULDBLOCKWaitReadable.superclass.should == Errno::EWOULDBLOCK
-    IO::EAGAINWaitReadable.ancestors.should include IO::WaitReadable
+    IO::EAGAINWaitReadable.ancestors.should.include? IO::WaitReadable
   end
 end
 
 describe "IO::EAGAINWaitWritable" do
   it "combines Errno::EAGAIN and IO::WaitWritable" do
     IO::EAGAINWaitWritable.superclass.should == Errno::EAGAIN
-    IO::EAGAINWaitWritable.ancestors.should include IO::WaitWritable
+    IO::EAGAINWaitWritable.ancestors.should.include? IO::WaitWritable
   end
 
   it "is the same as IO::EWOULDBLOCKWaitWritable if Errno::EAGAIN is the same as Errno::EWOULDBLOCK" do
     if Errno::EAGAIN.equal? Errno::EWOULDBLOCK
-      IO::EAGAINWaitWritable.should equal IO::EWOULDBLOCKWaitWritable
+      IO::EAGAINWaitWritable.should.equal? IO::EWOULDBLOCKWaitWritable
     else
-      IO::EAGAINWaitWritable.should_not equal IO::EWOULDBLOCKWaitWritable
+      IO::EAGAINWaitWritable.should_not.equal? IO::EWOULDBLOCKWaitWritable
     end
   end
 end
@@ -46,6 +40,6 @@ end
 describe "IO::EWOULDBLOCKWaitWritable" do
   it "combines Errno::EWOULDBLOCK and IO::WaitWritable" do
     IO::EWOULDBLOCKWaitWritable.superclass.should == Errno::EWOULDBLOCK
-    IO::EAGAINWaitWritable.ancestors.should include IO::WaitWritable
+    IO::EAGAINWaitWritable.ancestors.should.include? IO::WaitWritable
   end
 end
diff --git a/spec/ruby/core/exception/key_error_spec.rb b/spec/ruby/core/exception/key_error_spec.rb
index ad280279d8..c5e2b1efbc 100644
--- a/spec/ruby/core/exception/key_error_spec.rb
+++ b/spec/ruby/core/exception/key_error_spec.rb
@@ -1,15 +1,19 @@
 require_relative '../../spec_helper'
 
 describe "KeyError" do
-  ruby_version_is "2.6" do
-    it "accepts :receiver and :key options" do
-      receiver = mock("receiver")
-      key = mock("key")
+  it "accepts :receiver and :key options" do
+    receiver = mock("receiver")
+    key = mock("key")
 
-      error = KeyError.new(receiver: receiver, key: key)
+    error = KeyError.new(receiver: receiver, key: key)
 
-      error.receiver.should == receiver
-      error.key.should == key
-    end
+    error.receiver.should == receiver
+    error.key.should == key
+
+    error = KeyError.new("message", receiver: receiver, key: key)
+
+    error.message.should == "message"
+    error.receiver.should == receiver
+    error.key.should == key
   end
 end
diff --git a/spec/ruby/core/exception/name_error_spec.rb b/spec/ruby/core/exception/name_error_spec.rb
index d0a810029b..ddd51a92e5 100644
--- a/spec/ruby/core/exception/name_error_spec.rb
+++ b/spec/ruby/core/exception/name_error_spec.rb
@@ -1,24 +1,28 @@
 require_relative '../../spec_helper'
 
-describe "NameError" do
-  it "is a superclass of NoMethodError" do
-    NameError.should be_ancestor_of(NoMethodError)
-  end
-end
-
 describe "NameError.new" do
   it "should take optional name argument" do
     NameError.new("msg","name").name.should == "name"
   end
 
-  ruby_version_is "2.6" do
-    it "accepts a :receiver keyword argument" do
-      receiver = mock("receiver")
+  it "accepts a :receiver keyword argument" do
+    receiver = mock("receiver")
 
-      error = NameError.new("msg", :name, receiver: receiver)
+    error = NameError.new("msg", :name, receiver: receiver)
+
+    error.receiver.should == receiver
+    error.name.should == :name
+  end
+end
 
-      error.receiver.should == receiver
-      error.name.should == :name
+describe "NameError#dup" do
+  it "copies the name and receiver" do
+    begin
+      foo
+    rescue NameError => ne
+      name_error_dup = ne.dup
+      name_error_dup.name.should == :foo
+      name_error_dup.receiver.should == self
     end
   end
 end
diff --git a/spec/ruby/core/exception/name_spec.rb b/spec/ruby/core/exception/name_spec.rb
index d1def51f24..6e0e99d194 100644
--- a/spec/ruby/core/exception/name_spec.rb
+++ b/spec/ruby/core/exception/name_spec.rb
@@ -4,27 +4,25 @@ describe "NameError#name" do
   it "returns a method name as a symbol" do
     -> {
       doesnt_exist
-    }.should raise_error(NameError) {|e| e.name.should == :doesnt_exist }
+    }.should.raise(NameError) {|e| e.name.should == :doesnt_exist }
   end
 
   it "returns a constant name as a symbol" do
     -> {
       DoesntExist
-    }.should raise_error(NameError) {|e| e.name.should == :DoesntExist }
+    }.should.raise(NameError) {|e| e.name.should == :DoesntExist }
   end
 
   it "returns a constant name without namespace as a symbol" do
     -> {
       Object::DoesntExist
-    }.should raise_error(NameError) {|e| e.name.should == :DoesntExist }
+    }.should.raise(NameError) {|e| e.name.should == :DoesntExist }
   end
 
   it "returns a class variable name as a symbol" do
     -> {
-      -> {
-        @@doesnt_exist
-      }.should complain(/class variable access from toplevel/)
-    }.should raise_error(NameError) { |e| e.name.should == :@@doesnt_exist }
+      eval("class singleton_class::A; @@doesnt_exist end", binding, __FILE__, __LINE__)
+    }.should.raise(NameError) { |e| e.name.should == :@@doesnt_exist }
   end
 
   it "returns the first argument passed to the method when a NameError is raised from #instance_variable_get" do
@@ -32,7 +30,7 @@ describe "NameError#name" do
 
     -> {
       Object.new.instance_variable_get(invalid_ivar_name)
-    }.should raise_error(NameError) {|e| e.name.should equal(invalid_ivar_name) }
+    }.should.raise(NameError) {|e| e.name.should.equal?(invalid_ivar_name) }
   end
 
   it "returns the first argument passed to the method when a NameError is raised from #class_variable_get" do
@@ -40,6 +38,6 @@ describe "NameError#name" do
 
     -> {
       Object.class_variable_get(invalid_cvar_name)
-    }.should raise_error(NameError) {|e| e.name.should equal(invalid_cvar_name) }
+    }.should.raise(NameError) {|e| e.name.should.equal?(invalid_cvar_name) }
   end
 end
diff --git a/spec/ruby/core/exception/no_method_error_spec.rb b/spec/ruby/core/exception/no_method_error_spec.rb
index 28c3549562..9f92104082 100644
--- a/spec/ruby/core/exception/no_method_error_spec.rb
+++ b/spec/ruby/core/exception/no_method_error_spec.rb
@@ -10,15 +10,13 @@ describe "NoMethodError.new" do
     NoMethodError.new("msg").message.should == "msg"
   end
 
-  ruby_version_is "2.6" do
-    it "accepts a :receiver keyword argument" do
-      receiver = mock("receiver")
+  it "accepts a :receiver keyword argument" do
+    receiver = mock("receiver")
 
-      error = NoMethodError.new("msg", :name, receiver: receiver)
+    error = NoMethodError.new("msg", :name, receiver: receiver)
 
-      error.receiver.should == receiver
-      error.name.should == :name
-    end
+    error.receiver.should == receiver
+    error.name.should == :name
   end
 end
 
@@ -37,7 +35,7 @@ describe "NoMethodError#args" do
       NoMethodErrorSpecs::NoMethodErrorB.new.foo(1,a)
     rescue Exception => e
       e.args.should == [1,a]
-      e.args[1].should equal a
+      e.args[1].should.equal? a
     end
   end
 end
@@ -47,7 +45,7 @@ describe "NoMethodError#message" do
     begin
       NoMethodErrorSpecs::NoMethodErrorD.new.foo
     rescue Exception => e
-      e.should be_kind_of(NoMethodError)
+      e.should.is_a?(NoMethodError)
     end
   end
 
@@ -55,7 +53,7 @@ describe "NoMethodError#message" do
     begin
       NoMethodErrorSpecs::NoMethodErrorC.new.a_protected_method
     rescue Exception => e
-      e.should be_kind_of(NoMethodError)
+      e.should.is_a?(NoMethodError)
     end
   end
 
@@ -63,12 +61,120 @@ describe "NoMethodError#message" do
     begin
       NoMethodErrorSpecs::NoMethodErrorC.new.a_private_method
     rescue Exception => e
-      e.should be_kind_of(NoMethodError)
-      e.message.match(/private method/).should_not == nil
+      e.should.is_a?(NoMethodError)
+      e.message.lines[0].should =~ /private method [`']a_private_method' called for /
+    end
+  end
+
+  it "uses a literal name when receiver is nil" do
+    begin
+      nil.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for nil\Z/
+    end
+  end
+
+  it "uses a literal name when receiver is true" do
+    begin
+      true.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for true\Z/
+    end
+  end
+
+  it "uses a literal name when receiver is false" do
+    begin
+      false.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for false\Z/
+    end
+  end
+
+  it "uses #name when receiver is a class" do
+    klass = Class.new { def self.name; "MyClass"; end }
+
+    begin
+      klass.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for class MyClass\Z/
+    end
+  end
+
+  it "uses class' string representation when receiver is an anonymous class" do
+    klass = Class.new
+
+    begin
+      klass.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for class #<Class:0x\h+>\Z/
+    end
+  end
+
+  it "uses class' string representation when receiver is a singleton class" do
+    obj = Object.new
+    singleton_class = obj.singleton_class
+
+    begin
+      singleton_class.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for class #<Class:#<Object:0x\h+>>\Z/
+    end
+  end
+
+  it "uses #name when receiver is a module" do
+    mod = Module.new { def self.name; "MyModule"; end }
+
+    begin
+      mod.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for module MyModule\Z/
+    end
+  end
+
+  it "uses module's string representation when receiver is an anonymous module" do
+    m = Module.new
+
+    begin
+      m.foo
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for module #<Module:0x\h+>\Z/
+    end
+  end
+
+  it "uses class #name when receiver is an ordinary object" do
+    klass = Class.new { def self.name; "MyClass"; end }
+    instance = klass.new
+
+    begin
+      instance.bar
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']bar' for an instance of MyClass\Z/
     end
   end
 
-  it "calls receiver.inspect only when calling Exception#message" do
+  it "uses class string representation when receiver is an instance of anonymous class" do
+    klass = Class.new
+    instance = klass.new
+
+    begin
+      instance.bar
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']bar' for an instance of #<Class:0x\h+>\Z/
+    end
+  end
+
+  it "uses class name when receiver has a singleton class" do
+    instance = NoMethodErrorSpecs::NoMethodErrorA.new
+    def instance.foo; end
+
+    begin
+      instance.bar
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']bar' for #<NoMethodErrorSpecs::NoMethodErrorA:0x\h+>\Z/
+    end
+  end
+
+  it "does not call #inspect when calling Exception#message" do
     ScratchPad.record []
     test_class = Class.new do
       def inspect
@@ -77,30 +183,42 @@ describe "NoMethodError#message" do
       end
     end
     instance = test_class.new
+
     begin
       instance.bar
-    rescue Exception => e
-      e.name.should == :bar
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']bar' for an instance of #<Class:0x\h+>\Z/
       ScratchPad.recorded.should == []
-      e.message.should =~ /undefined method.+\bbar\b/
-      ScratchPad.recorded.should == [:inspect_called]
     end
   end
 
-  it "fallbacks to a simpler representation of the receiver when receiver.inspect raises an exception" do
-    test_class = Class.new do
-      def inspect
-        raise NoMethodErrorSpecs::InstanceException
-      end
+  it "does not truncate long class names" do
+    class_name = 'ExceptionSpecs::A' + 'a'*100
+
+    begin
+      eval <<~RUBY
+        class #{class_name}
+        end
+
+        obj = #{class_name}.new
+        obj.foo
+      RUBY
+    rescue NoMethodError => error
+      error.message.should =~ /\Aundefined method [`']foo' for an instance of #{class_name}\Z/
     end
-    instance = test_class.new
+  end
+end
+
+describe "NoMethodError#dup" do
+  it "copies the name, arguments and receiver" do
     begin
-      instance.bar
-    rescue Exception => e
-      e.name.should == :bar
-      message = e.message
-      message.should =~ /undefined method.+\bbar\b/
-      message.should include test_class.inspect
+      receiver = Object.new
+      receiver.foo(:one, :two)
+    rescue NoMethodError => nme
+      no_method_error_dup = nme.dup
+      no_method_error_dup.name.should == :foo
+      no_method_error_dup.receiver.should == receiver
+      no_method_error_dup.args.should == [:one, :two]
     end
   end
 end
diff --git a/spec/ruby/core/exception/range_error_spec.rb b/spec/ruby/core/exception/range_error_spec.rb
deleted file mode 100644
index 7cfbd0f1ec..0000000000
--- a/spec/ruby/core/exception/range_error_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "RangeError" do
-  it "is a superclass of FloatDomainError" do
-    RangeError.should be_ancestor_of(FloatDomainError)
-  end
-end
diff --git a/spec/ruby/core/exception/readagain_bytes_spec.rb b/spec/ruby/core/exception/readagain_bytes_spec.rb
deleted file mode 100644
index f7e8d9d1d3..0000000000
--- a/spec/ruby/core/exception/readagain_bytes_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::InvalidByteSequenceError#readagain_bytes" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/reason_spec.rb b/spec/ruby/core/exception/reason_spec.rb
index 6f18aaae13..d7022768b6 100644
--- a/spec/ruby/core/exception/reason_spec.rb
+++ b/spec/ruby/core/exception/reason_spec.rb
@@ -1,5 +1,13 @@
 require_relative '../../spec_helper'
 
 describe "LocalJumpError#reason" do
-  it "needs to be reviewed for spec completeness"
+  def get_me_a_return
+    Proc.new { return 42 }
+  end
+
+  it "returns 'return' for a return" do
+    -> { get_me_a_return.call }.should.raise(LocalJumpError) { |e|
+      e.reason.should == :return
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/receiver_spec.rb b/spec/ruby/core/exception/receiver_spec.rb
index 7c57d63c3e..6ecf640ad8 100644
--- a/spec/ruby/core/exception/receiver_spec.rb
+++ b/spec/ruby/core/exception/receiver_spec.rb
@@ -11,33 +11,31 @@ describe "NameError#receiver" do
 
     -> {
       receiver.doesnt_exist
-    }.should raise_error(NameError) {|e| e.receiver.should equal(receiver) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(receiver) }
   end
 
   it "returns the Object class when an undefined constant is called without namespace" do
     -> {
       DoesntExist
-    }.should raise_error(NameError) {|e| e.receiver.should equal(Object) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(Object) }
   end
 
   it "returns a class when an undefined constant is called" do
     -> {
       NameErrorSpecs::ReceiverClass::DoesntExist
-    }.should raise_error(NameError) {|e| e.receiver.should equal(NameErrorSpecs::ReceiverClass) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(NameErrorSpecs::ReceiverClass) }
   end
 
   it "returns the Object class when an undefined class variable is called" do
     -> {
-      -> {
-        @@doesnt_exist
-      }.should complain(/class variable access from toplevel/)
-    }.should raise_error(NameError) {|e| e.receiver.should equal(Object) }
+      eval("class singleton_class::A; @@doesnt_exist end", binding, __FILE__, __LINE__)
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(singleton_class::A) }
   end
 
   it "returns a class when an undefined class variable is called in a subclass' namespace" do
     -> {
       NameErrorSpecs::ReceiverClass.new.call_undefined_class_variable
-    }.should raise_error(NameError) {|e| e.receiver.should equal(NameErrorSpecs::ReceiverClass) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(NameErrorSpecs::ReceiverClass) }
   end
 
   it "returns the receiver when raised from #instance_variable_get" do
@@ -45,16 +43,16 @@ describe "NameError#receiver" do
 
     -> {
       receiver.instance_variable_get("invalid_ivar_name")
-    }.should raise_error(NameError) {|e| e.receiver.should equal(receiver) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(receiver) }
   end
 
   it "returns the receiver when raised from #class_variable_get" do
     -> {
       Object.class_variable_get("invalid_cvar_name")
-    }.should raise_error(NameError) {|e| e.receiver.should equal(Object) }
+    }.should.raise(NameError) {|e| e.receiver.should.equal?(Object) }
   end
 
   it "raises an ArgumentError when the receiver is none" do
-    -> { NameError.new.receiver }.should raise_error(ArgumentError)
+    -> { NameError.new.receiver }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/exception/result_spec.rb b/spec/ruby/core/exception/result_spec.rb
index 5ba26ebab1..451ff43af5 100644
--- a/spec/ruby/core/exception/result_spec.rb
+++ b/spec/ruby/core/exception/result_spec.rb
@@ -1,11 +1,5 @@
 require_relative '../../spec_helper'
 
-describe "StopIteration" do
-  it "is a subclass of IndexError" do
-    StopIteration.superclass.should equal(IndexError)
-  end
-end
-
 describe "StopIteration#result" do
   before :each do
     obj = Object.new
@@ -20,10 +14,8 @@ describe "StopIteration#result" do
   it "returns the method-returned-object from an Enumerator" do
     @enum.next
     @enum.next
-    -> { @enum.next }.should(
-      raise_error(StopIteration) do |error|
-        error.result.should equal(:method_returned)
-      end
-    )
+    -> { @enum.next }.should.raise(StopIteration) { |error|
+      error.result.should.equal?(:method_returned)
+    }
   end
 end
diff --git a/spec/ruby/core/exception/script_error_spec.rb b/spec/ruby/core/exception/script_error_spec.rb
deleted file mode 100644
index e33a5d3a58..0000000000
--- a/spec/ruby/core/exception/script_error_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ScriptError" do
-   it "is a superclass of LoadError" do
-     ScriptError.should be_ancestor_of(LoadError)
-   end
-
-   it "is a superclass of NotImplementedError" do
-     ScriptError.should be_ancestor_of(NotImplementedError)
-   end
-
-   it "is a superclass of SyntaxError" do
-     ScriptError.should be_ancestor_of(SyntaxError)
-   end
-end
diff --git a/spec/ruby/core/exception/set_backtrace_spec.rb b/spec/ruby/core/exception/set_backtrace_spec.rb
index ba2e1bf7aa..2cd93326ec 100644
--- a/spec/ruby/core/exception/set_backtrace_spec.rb
+++ b/spec/ruby/core/exception/set_backtrace_spec.rb
@@ -1,56 +1,23 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/common'
+require_relative 'shared/set_backtrace'
 
 describe "Exception#set_backtrace" do
-  it "accepts an Array of Strings" do
-    err = RuntimeError.new
-    err.set_backtrace ["unhappy"]
-    err.backtrace.should == ["unhappy"]
-  end
-
   it "allows the user to set the backtrace from a rescued exception" do
     bt  = ExceptionSpecs::Backtrace.backtrace
     err = RuntimeError.new
+    err.backtrace.should == nil
+    err.backtrace_locations.should == nil
 
     err.set_backtrace bt
-    err.backtrace.should == bt
-  end
-
-  it "accepts an empty Array" do
-    err = RuntimeError.new
-    err.set_backtrace []
-    err.backtrace.should == []
-  end
-
-  it "accepts a String" do
-    err = RuntimeError.new
-    err.set_backtrace "unhappy"
-    err.backtrace.should == ["unhappy"]
-  end
 
-  it "accepts nil" do
-    err = RuntimeError.new
-    err.set_backtrace nil
-    err.backtrace.should be_nil
-  end
-
-  it "raises a TypeError when passed a Symbol" do
-    err = RuntimeError.new
-    -> { err.set_backtrace :unhappy }.should raise_error(TypeError)
+    err.backtrace.should == bt
+    err.backtrace_locations.should == nil
   end
 
-  it "raises a TypeError when the Array contains a Symbol" do
+  it_behaves_like :exception_set_backtrace, -> backtrace {
     err = RuntimeError.new
-    -> { err.set_backtrace ["String", :unhappy] }.should raise_error(TypeError)
-  end
-
-  it "raises a TypeError when the array contains nil" do
-    err = Exception.new
-    -> { err.set_backtrace ["String", nil] }.should raise_error(TypeError)
-  end
-
-  it "raises a TypeError when the argument is a nested array" do
-    err = Exception.new
-    -> { err.set_backtrace ["String", ["String"]] }.should raise_error(TypeError)
-  end
+    err.set_backtrace(backtrace)
+    err
+  }
 end
diff --git a/spec/ruby/core/exception/shared/new.rb b/spec/ruby/core/exception/shared/new.rb
index bcde8ee4b2..048fd14dd2 100644
--- a/spec/ruby/core/exception/shared/new.rb
+++ b/spec/ruby/core/exception/shared/new.rb
@@ -1,6 +1,6 @@
 describe :exception_new, shared: true do
   it "creates a new instance of Exception" do
-    Exception.should be_ancestor_of(Exception.send(@method).class)
+    Exception.send(@method).class.ancestors.should.include?(Exception)
   end
 
   it "sets the message of the Exception when passes a message" do
@@ -12,7 +12,7 @@ describe :exception_new, shared: true do
   end
 
   it "returns the exception when it has a custom constructor" do
-    ExceptionSpecs::ConstructorException.send(@method).should be_kind_of(ExceptionSpecs::ConstructorException)
+    ExceptionSpecs::ConstructorException.send(@method).should.is_a?(ExceptionSpecs::ConstructorException)
   end
 
 end
diff --git a/spec/ruby/core/exception/shared/set_backtrace.rb b/spec/ruby/core/exception/shared/set_backtrace.rb
new file mode 100644
index 0000000000..934bf3dc5f
--- /dev/null
+++ b/spec/ruby/core/exception/shared/set_backtrace.rb
@@ -0,0 +1,64 @@
+require_relative '../fixtures/common'
+
+describe :exception_set_backtrace, shared: true do
+  it "accepts an Array of Strings" do
+    err = @method.call(["unhappy"])
+    err.backtrace.should == ["unhappy"]
+  end
+
+  it "allows the user to set the backtrace from a rescued exception" do
+    bt  = ExceptionSpecs::Backtrace.backtrace
+    err = @method.call(bt)
+    err.backtrace.should == bt
+  end
+
+  ruby_version_is "3.4" do
+    it "allows the user to set backtrace locations from a rescued exception" do
+      bt_locations = ExceptionSpecs::Backtrace.backtrace_locations
+      err = @method.call(bt_locations)
+      err.backtrace_locations.size.should == bt_locations.size
+      err.backtrace_locations.each_with_index do |loc, index|
+        other_loc = bt_locations[index]
+
+        loc.path.should == other_loc.path
+        loc.label.should == other_loc.label
+        loc.base_label.should == other_loc.base_label
+        loc.lineno.should == other_loc.lineno
+        loc.absolute_path.should == other_loc.absolute_path
+        loc.to_s.should == other_loc.to_s
+      end
+      err.backtrace.size.should == err.backtrace_locations.size
+    end
+  end
+
+  it "accepts an empty Array" do
+    err = @method.call([])
+    err.backtrace.should == []
+  end
+
+  it "accepts a String" do
+    err = @method.call("unhappy")
+    err.backtrace.should == ["unhappy"]
+  end
+
+  it "accepts nil" do
+    err = @method.call(nil)
+    err.backtrace.should == nil
+  end
+
+  it "raises a TypeError when passed a Symbol" do
+    -> { @method.call(:unhappy) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the Array contains a Symbol" do
+    -> { @method.call(["String", :unhappy]) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the array contains nil" do
+    -> { @method.call(["String", nil]) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the argument is a nested array" do
+    -> { @method.call(["String", ["String"]]) }.should.raise(TypeError)
+  end
+end
diff --git a/spec/ruby/core/exception/signal_exception_spec.rb b/spec/ruby/core/exception/signal_exception_spec.rb
index e0b30236f7..010181bc55 100644
--- a/spec/ruby/core/exception/signal_exception_spec.rb
+++ b/spec/ruby/core/exception/signal_exception_spec.rb
@@ -9,7 +9,7 @@ describe "SignalException.new" do
   end
 
   it "raises an exception with an invalid signal number" do
-    -> { SignalException.new(100000) }.should raise_error(ArgumentError)
+    -> { SignalException.new(100000) }.should.raise(ArgumentError)
   end
 
   it "takes a signal name without SIG prefix as the first argument" do
@@ -27,7 +27,11 @@ describe "SignalException.new" do
   end
 
   it "raises an exception with an invalid signal name" do
-    -> { SignalException.new("NONEXISTENT") }.should raise_error(ArgumentError)
+    -> { SignalException.new("NONEXISTENT") }.should.raise(ArgumentError)
+  end
+
+  it "raises an exception with an invalid first argument type" do
+    -> { SignalException.new(Object.new) }.should.raise(ArgumentError)
   end
 
   it "takes a signal symbol without SIG prefix as the first argument" do
@@ -45,7 +49,7 @@ describe "SignalException.new" do
   end
 
   it "raises an exception with an invalid signal name" do
-    -> { SignalException.new(:NONEXISTENT) }.should raise_error(ArgumentError)
+    -> { SignalException.new(:NONEXISTENT) }.should.raise(ArgumentError)
   end
 
   it "takes an optional message argument with a signal number" do
@@ -56,7 +60,7 @@ describe "SignalException.new" do
   end
 
   it "raises an exception for an optional argument with a signal name" do
-    -> { SignalException.new("INT","name") }.should raise_error(ArgumentError)
+    -> { SignalException.new("INT","name") }.should.raise(ArgumentError)
   end
 end
 
@@ -72,3 +76,48 @@ describe "rescuing SignalException" do
     end
   end
 end
+
+describe "SignalException" do
+  it "can be rescued" do
+    ruby_exe(<<-RUBY)
+      begin
+        raise SignalException, 'SIGKILL'
+      rescue SignalException
+        exit(0)
+      end
+      exit(1)
+    RUBY
+
+    $?.exitstatus.should == 0
+  end
+
+  platform_is_not :windows do
+    it "runs after at_exit" do
+      output = ruby_exe(<<-RUBY, exit_status: :SIGKILL)
+        at_exit do
+          puts "hello"
+          $stdout.flush
+        end
+
+        raise SignalException, 'SIGKILL'
+      RUBY
+
+      $?.termsig.should == Signal.list.fetch("KILL")
+      output.should == "hello\n"
+    end
+
+    it "cannot be trapped with Signal.trap" do
+      ruby_exe(<<-RUBY, exit_status: :SIGPROF)
+        Signal.trap("PROF") {}
+        raise(SignalException, "PROF")
+      RUBY
+
+      $?.termsig.should == Signal.list.fetch("PROF")
+    end
+
+    it "self-signals for USR1" do
+      ruby_exe("raise(SignalException, 'USR1')", exit_status: :SIGUSR1)
+      $?.termsig.should == Signal.list.fetch('USR1')
+    end
+  end
+end
diff --git a/spec/ruby/core/exception/signm_spec.rb b/spec/ruby/core/exception/signm_spec.rb
index 8e3adcddae..cabcc7ad58 100644
--- a/spec/ruby/core/exception/signm_spec.rb
+++ b/spec/ruby/core/exception/signm_spec.rb
@@ -1,5 +1,9 @@
 require_relative '../../spec_helper'
 
 describe "SignalException#signm" do
-  it "needs to be reviewed for spec completeness"
+  it "returns the signal name" do
+    -> { Process.kill(:TERM, Process.pid) }.should.raise(SignalException) { |e|
+      e.signm.should == 'SIGTERM'
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/signo_spec.rb b/spec/ruby/core/exception/signo_spec.rb
index 2d04cd7805..46e79a8daf 100644
--- a/spec/ruby/core/exception/signo_spec.rb
+++ b/spec/ruby/core/exception/signo_spec.rb
@@ -1,5 +1,9 @@
 require_relative '../../spec_helper'
 
 describe "SignalException#signo" do
-  it "needs to be reviewed for spec completeness"
+  it "returns the signal number" do
+    -> { Process.kill(:TERM, Process.pid) }.should.raise(SignalException) { |e|
+      e.signo.should == Signal.list['TERM']
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/source_encoding_name_spec.rb b/spec/ruby/core/exception/source_encoding_name_spec.rb
deleted file mode 100644
index bd8bc359b6..0000000000
--- a/spec/ruby/core/exception/source_encoding_name_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::UndefinedConversionError#source_encoding_name" do
-  it "needs to be reviewed for spec completeness"
-end
-
-describe "Encoding::InvalidByteSequenceError#source_encoding_name" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/source_encoding_spec.rb b/spec/ruby/core/exception/source_encoding_spec.rb
deleted file mode 100644
index 65ac98d791..0000000000
--- a/spec/ruby/core/exception/source_encoding_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Encoding::UndefinedConversionError#source_encoding" do
-  it "needs to be reviewed for spec completeness"
-end
-
-describe "Encoding::InvalidByteSequenceError#source_encoding" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/exception/standard_error_spec.rb b/spec/ruby/core/exception/standard_error_spec.rb
index 1b469b5090..b05d247f67 100644
--- a/spec/ruby/core/exception/standard_error_spec.rb
+++ b/spec/ruby/core/exception/standard_error_spec.rb
@@ -1,56 +1,23 @@
 require_relative '../../spec_helper'
 
 describe "StandardError" do
-  it "is a superclass of ArgumentError" do
-    StandardError.should be_ancestor_of(ArgumentError)
-  end
-
-  it "is a superclass of IOError" do
-    StandardError.should be_ancestor_of(IOError)
-  end
-
-  it "is a superclass of IndexError" do
-    StandardError.should be_ancestor_of(IndexError)
-  end
-
-  it "is a superclass of LocalJumpError" do
-    StandardError.should be_ancestor_of(LocalJumpError)
-  end
-
-  it "is a superclass of NameError" do
-    StandardError.should be_ancestor_of(NameError)
-  end
-
-  it "is a superclass of RangeError" do
-    StandardError.should be_ancestor_of(RangeError)
-  end
-
-  it "is a superclass of RegexpError" do
-    StandardError.should be_ancestor_of(RegexpError)
-  end
-
-  it "is a superclass of RuntimeError" do
-    StandardError.should be_ancestor_of(RuntimeError)
-  end
-
-  it "is a superclass of SystemCallError" do
-    StandardError.should be_ancestor_of(SystemCallError.new("").class)
-  end
-  it "is a superclass of ThreadError" do
-    StandardError.should be_ancestor_of(ThreadError)
-  end
-
-  it "is a superclass of TypeError" do
-    StandardError.should be_ancestor_of(TypeError)
+  it "rescues StandardError" do
+    begin
+      raise StandardError
+    rescue => exception
+      exception.class.should == StandardError
+    end
   end
 
-  it "is a superclass of ZeroDivisionError" do
-    StandardError.should be_ancestor_of(ZeroDivisionError)
+  it "rescues subclass of StandardError" do
+    begin
+      raise RuntimeError
+    rescue => exception
+      exception.class.should == RuntimeError
+    end
   end
 
-  ruby_version_is '2.5' do
-    it "is a superclass of FrozenError" do
-      StandardError.should be_ancestor_of(FrozenError)
-    end
+  it "does not rescue superclass of StandardError" do
+    -> { begin; raise Exception; rescue; end }.should.raise(Exception)
   end
 end
diff --git a/spec/ruby/core/exception/status_spec.rb b/spec/ruby/core/exception/status_spec.rb
index 1609bff3a5..7369b0815d 100644
--- a/spec/ruby/core/exception/status_spec.rb
+++ b/spec/ruby/core/exception/status_spec.rb
@@ -1,5 +1,9 @@
 require_relative '../../spec_helper'
 
 describe "SystemExit#status" do
-  it "needs to be reviewed for spec completeness"
+  it "returns the exit status" do
+    -> { exit 42 }.should.raise(SystemExit) { |e|
+      e.status.should == 42
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/success_spec.rb b/spec/ruby/core/exception/success_spec.rb
index 82e3df92c6..5ab8f94454 100644
--- a/spec/ruby/core/exception/success_spec.rb
+++ b/spec/ruby/core/exception/success_spec.rb
@@ -1,5 +1,15 @@
 require_relative '../../spec_helper'
 
 describe "SystemExit#success?" do
-  it "needs to be reviewed for spec completeness"
+  it "returns true if the process exited successfully" do
+    -> { exit 0 }.should.raise(SystemExit) { |e|
+      e.should.success?
+    }
+  end
+
+  it "returns false if the process exited unsuccessfully" do
+    -> { exit(-1) }.should.raise(SystemExit) { |e|
+      e.should_not.success?
+    }
+  end
 end
diff --git a/spec/ruby/core/exception/syntax_error_spec.rb b/spec/ruby/core/exception/syntax_error_spec.rb
new file mode 100644
index 0000000000..66eb5649aa
--- /dev/null
+++ b/spec/ruby/core/exception/syntax_error_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+
+describe "SyntaxError#path" do
+  it "returns the file path provided to eval" do
+    filename = "speccing.rb"
+
+    -> {
+      eval("if true", TOPLEVEL_BINDING, filename)
+    }.should.raise(SyntaxError) { |e|
+      e.path.should == filename
+    }
+  end
+
+  it "returns the file path that raised an exception" do
+    expected_path = fixture(__FILE__, "syntax_error.rb")
+
+    -> {
+      require_relative "fixtures/syntax_error"
+    }.should.raise(SyntaxError) { |e| e.path.should == expected_path }
+  end
+
+  it "returns nil when constructed directly" do
+    SyntaxError.new.path.should == nil
+  end
+end
diff --git a/spec/ruby/core/exception/system_call_error_spec.rb b/spec/ruby/core/exception/system_call_error_spec.rb
index c07c8af72c..da01c5b6b0 100644
--- a/spec/ruby/core/exception/system_call_error_spec.rb
+++ b/spec/ruby/core/exception/system_call_error_spec.rb
@@ -14,47 +14,113 @@ describe "SystemCallError" do
     end
 
     exc = ExceptionSpecs::SCESub.new
-    ScratchPad.recorded.should equal(:initialize)
-    exc.should be_an_instance_of(ExceptionSpecs::SCESub)
+    ScratchPad.recorded.should.equal?(:initialize)
+    exc.should.instance_of?(ExceptionSpecs::SCESub)
+  ensure
+    ExceptionSpecs.send(:remove_const, :SCESub)
   end
 end
 
 describe "SystemCallError.new" do
+  before :all do
+    @example_errno = Errno::EINVAL::Errno
+    @example_errno_class = Errno::EINVAL
+    @last_known_errno = Errno.constants.size - 1
+    @unknown_errno = Errno.constants.size
+    @some_human_readable = /[[:graph:]]+/
+  end
+
   it "requires at least one argument" do
-    -> { SystemCallError.new }.should raise_error(ArgumentError)
+    -> { SystemCallError.new }.should.raise(ArgumentError)
   end
 
-  it "accepts single Fixnum argument as errno" do
+  it "accepts single Integer argument as errno" do
     SystemCallError.new(-2**24).errno.should == -2**24
-    SystemCallError.new(42).errno.should == 42
+    SystemCallError.new(-1).errno.should == -1
+    SystemCallError.new(0).errno.should == 0
+    SystemCallError.new(@last_known_errno).errno.should == @last_known_errno
+    SystemCallError.new(@unknown_errno).errno.should == @unknown_errno
     SystemCallError.new(2**24).errno.should == 2**24
   end
 
+  it "constructs a SystemCallError for an unknown error number" do
+    SystemCallError.new(-2**24).should.instance_of?(SystemCallError)
+    SystemCallError.new(-1).should.instance_of?(SystemCallError)
+    SystemCallError.new(@unknown_errno).should.instance_of?(SystemCallError)
+    SystemCallError.new(2**24).should.instance_of?(SystemCallError)
+  end
+
   it "constructs the appropriate Errno class" do
-    # EINVAL should be more or less mortable across the platforms,
-    # so let's use it then.
-    SystemCallError.new(22).should be_kind_of(SystemCallError)
-    SystemCallError.new(22).should be_an_instance_of(Errno::EINVAL)
-    SystemCallError.new(2**28).should be_an_instance_of(SystemCallError)
+    e = SystemCallError.new(@example_errno)
+    e.should.is_a?(SystemCallError)
+    e.should.instance_of?(@example_errno_class)
+  end
+
+  it "sets an error message corresponding to an appropriate Errno class" do
+    e = SystemCallError.new(@example_errno)
+    e.message.should == 'Invalid argument'
   end
 
   it "accepts an optional custom message preceding the errno" do
-    exc = SystemCallError.new("custom message", 22)
-    exc.should be_an_instance_of(Errno::EINVAL)
-    exc.errno.should == 22
-    exc.message.should == "Invalid argument - custom message"
+    exc = SystemCallError.new("custom message", @example_errno)
+    exc.should.instance_of?(@example_errno_class)
+    exc.errno.should == @example_errno
+    exc.message.should == 'Invalid argument - custom message'
   end
 
   it "accepts an optional third argument specifying the location" do
-    exc = SystemCallError.new("custom message", 22, "location")
-    exc.should be_an_instance_of(Errno::EINVAL)
-    exc.errno.should == 22
-    exc.message.should == "Invalid argument @ location - custom message"
+    exc = SystemCallError.new("custom message", @example_errno, "location")
+    exc.should.instance_of?(@example_errno_class)
+    exc.errno.should == @example_errno
+    exc.message.should == 'Invalid argument @ location - custom message'
+  end
+
+  it "coerces location if it is not a String" do
+    e = SystemCallError.new('foo', 1, :not_a_string)
+    e.message.should =~ /@ not_a_string - foo/
   end
 
   it "returns an arity of -1 for the initialize method" do
     SystemCallError.instance_method(:initialize).arity.should == -1
   end
+
+  it "converts to Integer if errno is a Float" do
+    SystemCallError.new('foo', 2.0).should == SystemCallError.new('foo', 2)
+    SystemCallError.new('foo', 2.9).should == SystemCallError.new('foo', 2)
+  end
+
+  it "treats nil errno as unknown error value" do
+    SystemCallError.new(nil).should.instance_of?(SystemCallError)
+  end
+
+  it "treats nil custom message as if it is not passed at all" do
+    exc = SystemCallError.new(nil, @example_errno)
+    exc.message.should == 'Invalid argument'
+  end
+
+  it "sets an 'unknown error' message when an unknown error number" do
+    SystemCallError.new(-1).message.should =~ @some_human_readable
+  end
+
+  it "adds a custom error message to an 'unknown error' message when an unknown error number and a custom message specified" do
+    SystemCallError.new("custom message", -1).message.should =~ /#{@some_human_readable}.* - custom message/
+  end
+
+  it "converts to Integer if errno is a Complex convertible to Integer" do
+    SystemCallError.new('foo', Complex(2.9, 0)).should == SystemCallError.new('foo', 2)
+  end
+
+  it "raises TypeError if message is not a String" do
+    -> { SystemCallError.new(:foo, 1) }.should.raise(TypeError, /no implicit conversion of Symbol into String/)
+  end
+
+  it "raises TypeError if errno is not an Integer" do
+    -> { SystemCallError.new('foo', 'bar') }.should.raise(TypeError, /no implicit conversion of String into Integer/)
+  end
+
+  it "raises RangeError if errno is a Complex not convertible to Integer" do
+    -> { SystemCallError.new('foo', Complex(2.9, 1)) }.should.raise(RangeError, /can't convert/)
+  end
 end
 
 describe "SystemCallError#errno" do
@@ -74,12 +140,7 @@ end
 
 describe "SystemCallError#message" do
   it "returns the default message when no message is given" do
-    platform_is :aix do
-      SystemCallError.new(2**28).message.should =~ /Error .*occurred/i
-    end
-    platform_is_not :aix do
-      SystemCallError.new(2**28).message.should =~ /Unknown error/i
-    end
+    SystemCallError.new(2**28).message.should =~ @some_human_readable
   end
 
   it "returns the message given as an argument to new" do
@@ -87,3 +148,16 @@ describe "SystemCallError#message" do
     SystemCallError.new("XXX").message.should =~ /XXX/
   end
 end
+
+describe "SystemCallError#dup" do
+  it "copies the errno" do
+    dup_sce = SystemCallError.new("message", 42).dup
+    dup_sce.errno.should == 42
+  end
+end
+
+describe "SystemCallError#backtrace" do
+  it "is nil if not raised" do
+    SystemCallError.new("message", 42).backtrace.should == nil
+  end
+end
diff --git a/spec/ruby/core/exception/system_exit_spec.rb b/spec/ruby/core/exception/system_exit_spec.rb
new file mode 100644
index 0000000000..d899844c4e
--- /dev/null
+++ b/spec/ruby/core/exception/system_exit_spec.rb
@@ -0,0 +1,59 @@
+require_relative '../../spec_helper'
+
+describe "SystemExit" do
+  describe "#initialize" do
+    it "accepts a status and message" do
+      exc = SystemExit.new(42, "message")
+      exc.status.should == 42
+      exc.message.should == "message"
+
+      exc = SystemExit.new(true, "message")
+      exc.status.should == 0
+      exc.message.should == "message"
+
+      exc = SystemExit.new(false, "message")
+      exc.status.should == 1
+      exc.message.should == "message"
+    end
+
+    it "accepts a status only" do
+      exc = SystemExit.new(42)
+      exc.status.should == 42
+      exc.message.should == "SystemExit"
+
+      exc = SystemExit.new(true)
+      exc.status.should == 0
+      exc.message.should == "SystemExit"
+
+      exc = SystemExit.new(false)
+      exc.status.should == 1
+      exc.message.should == "SystemExit"
+    end
+
+    it "accepts a message only" do
+      exc = SystemExit.new("message")
+      exc.status.should == 0
+      exc.message.should == "message"
+    end
+
+    it "accepts no arguments" do
+      exc = SystemExit.new
+      exc.status.should == 0
+      exc.message.should == "SystemExit"
+    end
+  end
+
+  it "sets the exit status and exits silently when raised" do
+    code = 'raise SystemExit.new(7)'
+    result = ruby_exe(code, args: "2>&1", exit_status: 7)
+    result.should == ""
+    $?.exitstatus.should == 7
+  end
+
+  it "sets the exit status and exits silently when raised when subclassed" do
+    code = 'class CustomExit < SystemExit; end; raise CustomExit.new(8)'
+    result = ruby_exe(code, args: "2>&1", exit_status: 8)
+    result.should == ""
+    $?.exitstatus.should == 8
+  end
+end
diff --git a/spec/ruby/core/exception/system_stack_error_spec.rb b/spec/ruby/core/exception/system_stack_error_spec.rb
deleted file mode 100644
index 0343d2da59..0000000000
--- a/spec/ruby/core/exception/system_stack_error_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "SystemStackError" do
-  it "is a subclass of Exception" do
-    SystemStackError.superclass.should == Exception
-  end
-end
diff --git a/spec/ruby/core/exception/to_s_spec.rb b/spec/ruby/core/exception/to_s_spec.rb
index 8570b18cfd..65c0d73a98 100644
--- a/spec/ruby/core/exception/to_s_spec.rb
+++ b/spec/ruby/core/exception/to_s_spec.rb
@@ -19,5 +19,19 @@ describe "Exception#to_s" do
 end
 
 describe "NameError#to_s" do
-  it "needs to be reviewed for spec completeness"
+  it "raises its own message for an undefined variable" do
+    begin
+      puts not_defined
+    rescue => exception
+      exception.message.should =~ /undefined local variable or method [`']not_defined'/
+    end
+  end
+
+  it "raises its own message for an undefined constant" do
+    begin
+      puts NotDefined
+    rescue => exception
+      exception.message.should =~ /uninitialized constant NotDefined/
+    end
+  end
 end
diff --git a/spec/ruby/core/exception/top_level_spec.rb b/spec/ruby/core/exception/top_level_spec.rb
new file mode 100644
index 0000000000..cc961d06d5
--- /dev/null
+++ b/spec/ruby/core/exception/top_level_spec.rb
@@ -0,0 +1,65 @@
+require_relative '../../spec_helper'
+
+describe "An Exception reaching the top level" do
+  it "is printed on STDERR" do
+    ruby_exe('raise "foo"', args: "2>&1", exit_status: 1).should =~ /in [`']<main>': foo \(RuntimeError\)/
+  end
+
+  it "the Exception#cause is printed to STDERR with backtraces" do
+    code = <<-RUBY
+    def raise_cause
+      raise "the cause" # 2
+    end
+    def raise_wrapped
+      raise "wrapped" # 5
+    end
+    begin
+      raise_cause # 8
+    rescue
+      raise_wrapped # 10
+    end
+    RUBY
+    lines = ruby_exe(code, args: "2>&1", exit_status: 1).lines
+
+    lines.map! { |l| l.chomp[/:(\d+:in.+)/, 1] }
+    lines[0].should =~ /\A5:in [`'](?:Object#)?raise_wrapped': wrapped \(RuntimeError\)\z/
+    if lines[1].include? 'rescue in'
+      # CRuby < 3.4 has an extra 'rescue in' backtrace entry
+      lines[1].should =~ /\A10:in [`']rescue in <main>'\z/
+      lines.delete_at 1
+      lines[1].should =~ /\A7:in [`']<main>'\z/
+    else
+      lines[1].should =~ /\A10:in [`']<main>'\z/
+    end
+    lines[2].should =~ /\A2:in [`'](?:Object#)?raise_cause': the cause \(RuntimeError\)\z/
+    lines[3].should =~ /\A8:in [`']<main>'\z/
+    lines.size.should == 4
+  end
+
+  describe "with a custom backtrace" do
+    it "is printed on STDERR" do
+      code = <<-RUBY
+      raise RuntimeError, "foo", [
+        "/dir/foo.rb:10:in `raising'",
+        "/dir/bar.rb:20:in `caller'",
+      ]
+      RUBY
+      ruby_exe(code, args: "2>&1", exit_status: 1).should == <<-EOS
+/dir/foo.rb:10:in `raising': foo (RuntimeError)
+\tfrom /dir/bar.rb:20:in `caller'
+      EOS
+    end
+  end
+
+  describe "kills all threads and fibers, ensure clauses are only run for threads current fibers, not for suspended fibers" do
+    it "with ensure on the root fiber" do
+      file = fixture(__FILE__, "thread_fiber_ensure.rb")
+      ruby_exe(file, args: "2>&1", exit_status: 0).should == "current fiber ensure\n"
+    end
+
+    it "with ensure on non-root fiber" do
+      file = fixture(__FILE__, "thread_fiber_ensure_non_root_fiber.rb")
+      ruby_exe(file, args: "2>&1", exit_status: 0).should == "current fiber ensure\n"
+    end
+  end
+end
diff --git a/spec/ruby/core/exception/uncaught_throw_error_spec.rb b/spec/ruby/core/exception/uncaught_throw_error_spec.rb
index 57f391d755..9267df6670 100644
--- a/spec/ruby/core/exception/uncaught_throw_error_spec.rb
+++ b/spec/ruby/core/exception/uncaught_throw_error_spec.rb
@@ -1,11 +1,5 @@
 require_relative '../../spec_helper'
 
-describe "UncaughtThrowError" do
-  it "is a subclass of ArgumentError" do
-    ArgumentError.should be_ancestor_of(UncaughtThrowError)
-  end
-end
-
 describe "UncaughtThrowError#tag" do
   it "returns the object thrown" do
     begin
diff --git a/spec/ruby/core/false/case_compare_spec.rb b/spec/ruby/core/false/case_compare_spec.rb
new file mode 100644
index 0000000000..0bd0ab44ae
--- /dev/null
+++ b/spec/ruby/core/false/case_compare_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+describe "FalseClass#===" do
+  it "returns true for false" do
+    (false === false).should == true
+  end
+
+  it "returns false for non-false object" do
+    (false === 0).should == false
+    (false === "").should == false
+    (false === Object).should == false
+    (false === nil).should == false
+  end
+end
diff --git a/spec/ruby/core/false/dup_spec.rb b/spec/ruby/core/false/dup_spec.rb
index 1a569a2f4f..b0eb85529e 100644
--- a/spec/ruby/core/false/dup_spec.rb
+++ b/spec/ruby/core/false/dup_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "FalseClass#dup" do
   it "returns self" do
-    false.dup.should equal(false)
+    false.dup.should.equal?(false)
   end
 end
diff --git a/spec/ruby/core/false/falseclass_spec.rb b/spec/ruby/core/false/falseclass_spec.rb
index c018ef2421..8dfe5ae891 100644
--- a/spec/ruby/core/false/falseclass_spec.rb
+++ b/spec/ruby/core/false/falseclass_spec.rb
@@ -4,12 +4,12 @@ describe "FalseClass" do
   it ".allocate raises a TypeError" do
     -> do
       FalseClass.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       FalseClass.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/false/singleton_method_spec.rb b/spec/ruby/core/false/singleton_method_spec.rb
new file mode 100644
index 0000000000..72aee8609a
--- /dev/null
+++ b/spec/ruby/core/false/singleton_method_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "FalseClass#singleton_method" do
+  it "raises regardless of whether FalseClass defines the method" do
+    -> { false.singleton_method(:foo) }.should.raise(NameError)
+    begin
+      def (false).foo; end
+      -> { false.singleton_method(:foo) }.should.raise(NameError)
+    ensure
+      FalseClass.send(:remove_method, :foo)
+    end
+  end
+end
diff --git a/spec/ruby/core/false/to_s_spec.rb b/spec/ruby/core/false/to_s_spec.rb
index c996d87000..9e24be26a2 100644
--- a/spec/ruby/core/false/to_s_spec.rb
+++ b/spec/ruby/core/false/to_s_spec.rb
@@ -5,13 +5,11 @@ describe "FalseClass#to_s" do
     false.to_s.should == "false"
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen string" do
-      false.to_s.frozen?.should == true
-    end
+  it "returns a frozen string" do
+    false.to_s.should.frozen?
+  end
 
-    it "always returns the same string" do
-      false.to_s.should equal(false.to_s)
-    end
+  it "always returns the same string" do
+    false.to_s.should.equal?(false.to_s)
   end
 end
diff --git a/spec/ruby/core/fiber/alive_spec.rb b/spec/ruby/core/fiber/alive_spec.rb
new file mode 100644
index 0000000000..6fb1229d95
--- /dev/null
+++ b/spec/ruby/core/fiber/alive_spec.rb
@@ -0,0 +1,44 @@
+require_relative '../../spec_helper'
+
+describe "Fiber#alive?" do
+  it "returns true for a Fiber that hasn't had #resume called" do
+    fiber = Fiber.new { true }
+    fiber.alive?.should == true
+  end
+
+  # FIXME: Better description?
+  it "returns true for a Fiber that's yielded to the caller" do
+    fiber = Fiber.new { Fiber.yield }
+    fiber.resume
+    fiber.alive?.should == true
+  end
+
+  it "returns true when called from its Fiber" do
+    fiber = Fiber.new { fiber.alive?.should == true }
+    fiber.resume
+  end
+
+  it "doesn't invoke the block associated with the Fiber" do
+    offthehook = mock('do not call')
+    offthehook.should_not_receive(:ring)
+    fiber = Fiber.new { offthehook.ring }
+    fiber.alive?
+  end
+
+  it "returns false for a Fiber that's dead" do
+    fiber = Fiber.new { true }
+    fiber.resume
+    -> { fiber.resume }.should.raise(FiberError)
+    fiber.alive?.should == false
+  end
+
+  it "always returns false for a dead Fiber" do
+    fiber = Fiber.new { true }
+    fiber.resume
+    -> { fiber.resume }.should.raise(FiberError)
+    fiber.alive?.should == false
+    -> { fiber.resume }.should.raise(FiberError)
+    fiber.alive?.should == false
+    fiber.alive?.should == false
+  end
+end
diff --git a/spec/ruby/core/fiber/blocking_spec.rb b/spec/ruby/core/fiber/blocking_spec.rb
new file mode 100644
index 0000000000..d5caf81fbe
--- /dev/null
+++ b/spec/ruby/core/fiber/blocking_spec.rb
@@ -0,0 +1,73 @@
+require_relative '../../spec_helper'
+require_relative 'shared/blocking'
+
+describe "Fiber.blocking?" do
+  it_behaves_like :non_blocking_fiber, -> { Fiber.blocking? }
+
+  context "when fiber is blocking" do
+    context "root Fiber of the main thread" do
+      it "returns 1 for blocking: true" do
+        fiber = Fiber.new(blocking: true) { Fiber.blocking? }
+        blocking = fiber.resume
+
+        blocking.should == 1
+      end
+    end
+
+    context "root Fiber of a new thread" do
+      it "returns 1 for blocking: true" do
+        thread = Thread.new do
+          fiber = Fiber.new(blocking: true) { Fiber.blocking? }
+          blocking = fiber.resume
+
+          blocking.should == 1
+        end
+
+        thread.join
+      end
+    end
+  end
+end
+
+describe "Fiber#blocking?" do
+  it_behaves_like :non_blocking_fiber, -> { Fiber.current.blocking? }
+
+  context "when fiber is blocking" do
+    context "root Fiber of the main thread" do
+      it "returns true for blocking: true" do
+        fiber = Fiber.new(blocking: true) { Fiber.current.blocking? }
+        blocking = fiber.resume
+
+        blocking.should == true
+      end
+    end
+
+    context "root Fiber of a new thread" do
+      it "returns true for blocking: true" do
+        thread = Thread.new do
+          fiber = Fiber.new(blocking: true) { Fiber.current.blocking? }
+          blocking = fiber.resume
+
+          blocking.should == true
+        end
+
+        thread.join
+      end
+    end
+  end
+end
+
+describe "Fiber.blocking" do
+  context "when fiber is non-blocking" do
+    it "can become blocking" do
+      fiber = Fiber.new(blocking: false) do
+        Fiber.blocking do |f|
+          f.blocking? ? :blocking : :non_blocking
+        end
+      end
+
+      blocking = fiber.resume
+      blocking.should == :blocking
+    end
+  end
+end
diff --git a/spec/ruby/core/fiber/current_spec.rb b/spec/ruby/core/fiber/current_spec.rb
new file mode 100644
index 0000000000..cc5c9117b6
--- /dev/null
+++ b/spec/ruby/core/fiber/current_spec.rb
@@ -0,0 +1,50 @@
+require_relative '../../spec_helper'
+
+describe "Fiber.current" do
+  it "returns the root Fiber when called outside of a Fiber" do
+    root = Fiber.current
+    root.should.instance_of?(Fiber)
+    # We can always transfer to the root Fiber; it will never die
+    5.times do
+      root.transfer.should == nil
+      root.alive?.should == true
+    end
+  end
+
+  it "returns the current Fiber when called from a Fiber" do
+    fiber = Fiber.new do
+      this = Fiber.current
+      this.should.instance_of?(Fiber)
+      this.should == fiber
+      this.alive?.should == true
+    end
+    fiber.resume
+  end
+
+  it "returns the current Fiber when called from a Fiber that transferred to another" do
+    states = []
+    fiber = Fiber.new do
+      states << :fiber
+      this = Fiber.current
+      this.should.instance_of?(Fiber)
+      this.should == fiber
+      this.alive?.should == true
+    end
+
+    fiber2 = Fiber.new do
+      states << :fiber2
+      fiber.transfer
+      flunk
+    end
+
+    fiber3 = Fiber.new do
+      states << :fiber3
+      fiber2.transfer
+      states << :fiber3_terminated
+    end
+
+    fiber3.resume
+
+    states.should == [:fiber3, :fiber2, :fiber, :fiber3_terminated]
+  end
+end
diff --git a/spec/ruby/core/fiber/fixtures/classes.rb b/spec/ruby/core/fiber/fixtures/classes.rb
new file mode 100644
index 0000000000..6b0e0fbc42
--- /dev/null
+++ b/spec/ruby/core/fiber/fixtures/classes.rb
@@ -0,0 +1,22 @@
+module FiberSpecs
+
+  class NewFiberToRaise
+    def self.raise(*args, **kwargs, &block)
+      fiber = Fiber.new do
+        if block_given?
+          block.call do
+            Fiber.yield
+          end
+        else
+          Fiber.yield
+        end
+      end
+
+      fiber.resume
+
+      fiber.raise(*args, **kwargs)
+    end
+  end
+
+  class CustomError < StandardError; end
+end
diff --git a/spec/ruby/core/fiber/fixtures/scheduler.rb b/spec/ruby/core/fiber/fixtures/scheduler.rb
new file mode 100644
index 0000000000..16bd2f6b44
--- /dev/null
+++ b/spec/ruby/core/fiber/fixtures/scheduler.rb
@@ -0,0 +1,35 @@
+module FiberSpecs
+
+  class LoggingScheduler
+    attr_reader :events
+    def initialize
+      @events = []
+    end
+
+    def block(*args)
+      @events << { event: :block, fiber: Fiber.current, args: args }
+      Fiber.yield
+    end
+
+    def io_wait(*args)
+      @events << { event: :io_wait, fiber: Fiber.current, args: args }
+      Fiber.yield
+    end
+
+    def kernel_sleep(*args)
+      @events << { event: :kernel_sleep, fiber: Fiber.current, args: args }
+      Fiber.yield
+    end
+
+    def unblock(*args)
+      @events << { event: :unblock, fiber: Fiber.current, args: args }
+      Fiber.yield
+    end
+
+    def fiber_interrupt(*args)
+      @events << { event: :fiber_interrupt, fiber: Fiber.current, args: args }
+      Fiber.yield
+    end
+  end
+
+end
diff --git a/spec/ruby/core/fiber/inspect_spec.rb b/spec/ruby/core/fiber/inspect_spec.rb
new file mode 100644
index 0000000000..fcfef20716
--- /dev/null
+++ b/spec/ruby/core/fiber/inspect_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../spec_helper'
+
+describe "Fiber#inspect" do
+  describe "status" do
+    it "is resumed for the root Fiber of a Thread" do
+      inspected = Thread.new { Fiber.current.inspect }.value
+      inspected.should =~ /\A#<Fiber:0x\h+ .*\(resumed\)>\z/
+    end
+
+    it "is created for a Fiber which did not run yet" do
+      inspected = Fiber.new {}.inspect
+      inspected.should =~ /\A#<Fiber:0x\h+ .+ \(created\)>\z/
+    end
+
+    it "is resumed for a Fiber which was resumed" do
+      inspected = Fiber.new { Fiber.current.inspect }.resume
+      inspected.should =~ /\A#<Fiber:0x\h+ .+ \(resumed\)>\z/
+    end
+
+    it "is resumed for a Fiber which was transferred" do
+      inspected = Fiber.new { Fiber.current.inspect }.transfer
+      inspected.should =~ /\A#<Fiber:0x\h+ .+ \(resumed\)>\z/
+    end
+
+    it "is suspended for a Fiber which was resumed and yielded" do
+      inspected = Fiber.new { Fiber.yield }.tap(&:resume).inspect
+      inspected.should =~ /\A#<Fiber:0x\h+ .+ \(suspended\)>\z/
+    end
+
+    it "is terminated for a Fiber which has terminated" do
+      inspected = Fiber.new {}.tap(&:resume).inspect
+      inspected.should =~ /\A#<Fiber:0x\h+ .+ \(terminated\)>\z/
+    end
+  end
+end
diff --git a/spec/ruby/core/fiber/kill_spec.rb b/spec/ruby/core/fiber/kill_spec.rb
new file mode 100644
index 0000000000..abf23ff176
--- /dev/null
+++ b/spec/ruby/core/fiber/kill_spec.rb
@@ -0,0 +1,88 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative '../../shared/kernel/raise'
+
+describe "Fiber#kill" do
+  it "kills a non-resumed fiber" do
+    fiber = Fiber.new{}
+
+    fiber.alive?.should == true
+
+    fiber.kill
+    fiber.alive?.should == false
+  end
+
+  it "kills a resumed fiber" do
+    fiber = Fiber.new{while true; Fiber.yield; end}
+    fiber.resume
+
+    fiber.alive?.should == true
+
+    fiber.kill
+    fiber.alive?.should == false
+  end
+
+  it "can kill itself" do
+    fiber = Fiber.new do
+      Fiber.current.kill
+    end
+
+    fiber.alive?.should == true
+
+    fiber.resume
+    fiber.alive?.should == false
+  end
+
+  it "kills a resumed fiber from a child" do
+    parent = Fiber.new do
+      child = Fiber.new do
+        parent.kill
+        parent.alive?.should == true
+      end
+
+      child.resume
+    end
+
+    parent.resume
+    parent.alive?.should == false
+  end
+
+  it "executes the ensure block" do
+    ensure_executed = false
+
+    fiber = Fiber.new do
+      while true; Fiber.yield; end
+    ensure
+      ensure_executed = true
+    end
+
+    fiber.resume
+    fiber.kill
+    ensure_executed.should == true
+  end
+
+  it "does not execute rescue block" do
+    rescue_executed = false
+
+    fiber = Fiber.new do
+      while true; Fiber.yield; end
+    rescue Exception
+      rescue_executed = true
+    end
+
+    fiber.resume
+    fiber.kill
+    rescue_executed.should == false
+  end
+
+  it "repeatedly kills a fiber" do
+    fiber = Fiber.new do
+      while true; Fiber.yield; end
+    ensure
+      while true; Fiber.yield; end
+    end
+
+    fiber.kill
+    fiber.alive?.should == false
+  end
+end
diff --git a/spec/ruby/core/fiber/new_spec.rb b/spec/ruby/core/fiber/new_spec.rb
index b43c1386be..d31167496d 100644
--- a/spec/ruby/core/fiber/new_spec.rb
+++ b/spec/ruby/core/fiber/new_spec.rb
@@ -4,7 +4,7 @@ describe "Fiber.new" do
   it "creates a fiber from the given block" do
     fiber = Fiber.new {}
     fiber.resume
-    fiber.should be_an_instance_of(Fiber)
+    fiber.should.instance_of?(Fiber)
   end
 
   it "creates a fiber from a subclass" do
@@ -12,17 +12,17 @@ describe "Fiber.new" do
     end
     fiber = MyFiber.new {}
     fiber.resume
-    fiber.should be_an_instance_of(MyFiber)
+    fiber.should.instance_of?(MyFiber)
   end
 
   it "raises an ArgumentError if called without a block" do
-    -> { Fiber.new }.should raise_error(ArgumentError)
+    -> { Fiber.new }.should.raise(ArgumentError)
   end
 
   it "does not invoke the block" do
     invoked = false
     fiber = Fiber.new { invoked = true }
-    invoked.should be_false
+    invoked.should == false
     fiber.resume
   end
 
diff --git a/spec/ruby/core/fiber/raise_spec.rb b/spec/ruby/core/fiber/raise_spec.rb
new file mode 100644
index 0000000000..107e5bd4ce
--- /dev/null
+++ b/spec/ruby/core/fiber/raise_spec.rb
@@ -0,0 +1,141 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative '../../shared/kernel/raise'
+
+describe "Fiber#raise" do
+  it "is a public method" do
+    Fiber.public_instance_methods.should.include?(:raise)
+  end
+
+  it_behaves_like :kernel_raise, :raise, FiberSpecs::NewFiberToRaise
+  it_behaves_like :kernel_raise_across_contexts, :raise, FiberSpecs::NewFiberToRaise
+  ruby_version_is "4.0" do
+    it_behaves_like :kernel_raise_with_cause, :raise, FiberSpecs::NewFiberToRaise
+  end
+
+  it 'raises RuntimeError by default' do
+    -> { FiberSpecs::NewFiberToRaise.raise }.should.raise(RuntimeError)
+  end
+
+  it "raises FiberError if Fiber is not born" do
+    fiber = Fiber.new { true }
+    -> { fiber.raise }.should.raise(FiberError, "cannot raise exception on unborn fiber")
+  end
+
+  it "raises FiberError if Fiber is dead" do
+    fiber = Fiber.new { true }
+    fiber.resume
+    -> { fiber.raise }.should.raise(FiberError, /dead fiber called|attempt to resume a terminated fiber/)
+  end
+
+  it 'accepts error class' do
+    -> { FiberSpecs::NewFiberToRaise.raise FiberSpecs::CustomError }.should.raise(FiberSpecs::CustomError)
+  end
+
+  it 'accepts error message' do
+    -> { FiberSpecs::NewFiberToRaise.raise "error message" }.should.raise(RuntimeError, "error message")
+  end
+
+  it 'does not accept array of backtrace information only' do
+    -> { FiberSpecs::NewFiberToRaise.raise ['foo'] }.should.raise(TypeError)
+  end
+
+  it 'does not accept integer' do
+    -> { FiberSpecs::NewFiberToRaise.raise 100 }.should.raise(TypeError)
+  end
+
+  it 'accepts error class with error message' do
+    -> { FiberSpecs::NewFiberToRaise.raise FiberSpecs::CustomError, 'test error' }.should.raise(FiberSpecs::CustomError, 'test error')
+  end
+
+  it 'accepts error class with error message and backtrace information' do
+    -> {
+      FiberSpecs::NewFiberToRaise.raise FiberSpecs::CustomError, 'test error', ['foo', 'boo']
+    }.should.raise(FiberSpecs::CustomError) { |e|
+      e.message.should == 'test error'
+      e.backtrace.should == ['foo', 'boo']
+    }
+  end
+
+  it 'does not accept only error message and backtrace information' do
+    -> { FiberSpecs::NewFiberToRaise.raise 'test error', ['foo', 'boo'] }.should.raise(TypeError)
+  end
+
+  it "raises a FiberError if invoked from a different Thread" do
+    fiber = Fiber.new { Fiber.yield }
+    fiber.resume
+    Thread.new do
+      -> {
+        fiber.raise
+      }.should.raise(FiberError, "fiber called across threads")
+    end.join
+  end
+
+  it "kills Fiber" do
+    fiber = Fiber.new { Fiber.yield :first; :second }
+    fiber.resume
+    -> { fiber.raise }.should.raise
+    -> { fiber.resume }.should.raise(FiberError, /dead fiber called|attempt to resume a terminated fiber/)
+  end
+
+  it "returns to calling fiber after raise" do
+    fiber_one = Fiber.new do
+      Fiber.yield :yield_one
+      :unreachable
+    end
+
+    fiber_two = Fiber.new do
+      results = []
+      results << fiber_one.resume
+      begin
+        fiber_one.raise
+      rescue
+        results << :rescued
+      end
+      results
+    end
+
+    fiber_two.resume.should == [:yield_one, :rescued]
+  end
+
+  ruby_version_is "3.4" do
+    it "raises on the resumed fiber" do
+      root_fiber = Fiber.current
+      f1 = Fiber.new { root_fiber.transfer }
+      f2 = Fiber.new { f1.resume }
+      f2.transfer
+
+      -> do
+        f2.raise(RuntimeError, "Expected error")
+      end.should.raise(RuntimeError, "Expected error")
+    end
+
+    it "raises on itself" do
+      -> do
+        Fiber.current.raise(RuntimeError, "Expected error")
+      end.should.raise(RuntimeError, "Expected error")
+    end
+
+    it "should raise on parent fiber" do
+      f2 = nil
+      f1 = Fiber.new do
+        # This is equivalent to Kernel#raise:
+        f2.raise(RuntimeError, "Expected error")
+      end
+      f2 = Fiber.new do
+        f1.resume
+      end
+
+      -> do
+        f2.resume
+      end.should.raise(RuntimeError, "Expected error")
+    end
+  end
+
+  it "transfers and raises on a transferring fiber" do
+    root = Fiber.current
+    fiber = Fiber.new { root.transfer }
+    fiber.transfer
+    -> { fiber.raise "msg" }.should.raise(RuntimeError, "msg")
+  end
+end
diff --git a/spec/ruby/core/fiber/resume_spec.rb b/spec/ruby/core/fiber/resume_spec.rb
index 97495c5059..e183cc10d9 100644
--- a/spec/ruby/core/fiber/resume_spec.rb
+++ b/spec/ruby/core/fiber/resume_spec.rb
@@ -1,14 +1,36 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/fiber/resume'
+require_relative 'shared/resume'
 
 describe "Fiber#resume" do
   it_behaves_like :fiber_resume, :resume
 end
 
 describe "Fiber#resume" do
+  it "runs until Fiber.yield" do
+    obj = mock('obj')
+    obj.should_not_receive(:do)
+    fiber = Fiber.new { 1 + 2; Fiber.yield; obj.do }
+    fiber.resume
+  end
+
+  it "resumes from the last call to Fiber.yield on subsequent invocations" do
+    fiber = Fiber.new { Fiber.yield :first; :second }
+    fiber.resume.should == :first
+    fiber.resume.should == :second
+  end
+
+  it "sets the block parameters to its arguments on the first invocation" do
+    first = mock('first')
+    first.should_receive(:arg).with(:first).twice
+
+    fiber = Fiber.new { |arg| first.arg arg; Fiber.yield; first.arg arg; }
+    fiber.resume :first
+    fiber.resume :second
+  end
+
   it "raises a FiberError if the Fiber tries to resume itself" do
     fiber = Fiber.new { fiber.resume }
-    -> { fiber.resume }.should raise_error(FiberError, /double resume/)
+    -> { fiber.resume }.should.raise(FiberError, /current fiber/)
   end
 
   it "returns control to the calling Fiber if called from one" do
@@ -45,4 +67,17 @@ describe "Fiber#resume" do
 
     ruby_exe(code).should == "ensure executed\n"
   end
+
+  it "can work with Fiber#transfer" do
+    fiber1 = Fiber.new { true }
+    fiber2 = Fiber.new { fiber1.transfer; Fiber.yield 10 ; Fiber.yield 20; raise }
+    fiber2.resume.should == 10
+    fiber2.resume.should == 20
+  end
+
+  it "raises a FiberError if the Fiber attempts to resume a resuming fiber" do
+    root_fiber = Fiber.current
+    fiber1 = Fiber.new { root_fiber.resume }
+    -> { fiber1.resume }.should.raise(FiberError, /attempt to resume a resuming fiber/)
+  end
 end
diff --git a/spec/ruby/core/fiber/scheduler_spec.rb b/spec/ruby/core/fiber/scheduler_spec.rb
new file mode 100644
index 0000000000..15a03c1479
--- /dev/null
+++ b/spec/ruby/core/fiber/scheduler_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative 'shared/scheduler'
+
+require "fiber"
+
+describe "Fiber.scheduler" do
+  it_behaves_like :scheduler, :scheduler
+end
diff --git a/spec/ruby/core/fiber/set_scheduler_spec.rb b/spec/ruby/core/fiber/set_scheduler_spec.rb
new file mode 100644
index 0000000000..82f6acbe86
--- /dev/null
+++ b/spec/ruby/core/fiber/set_scheduler_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative 'shared/scheduler'
+
+require "fiber"
+
+describe "Fiber.scheduler" do
+  it_behaves_like :scheduler, :set_scheduler
+end
diff --git a/spec/ruby/core/fiber/shared/blocking.rb b/spec/ruby/core/fiber/shared/blocking.rb
new file mode 100644
index 0000000000..21707e1ea7
--- /dev/null
+++ b/spec/ruby/core/fiber/shared/blocking.rb
@@ -0,0 +1,41 @@
+describe :non_blocking_fiber, shared: true do
+  context "root Fiber of the main thread" do
+    it "returns false" do
+      fiber = Fiber.new { @method.call }
+      blocking = fiber.resume
+
+      blocking.should == false
+    end
+
+    it "returns false for blocking: false" do
+      fiber = Fiber.new(blocking: false) { @method.call }
+      blocking = fiber.resume
+
+      blocking.should == false
+    end
+  end
+
+  context "root Fiber of a new thread" do
+    it "returns false" do
+      thread = Thread.new do
+        fiber = Fiber.new { @method.call }
+        blocking = fiber.resume
+
+        blocking.should == false
+      end
+
+      thread.join
+    end
+
+    it "returns false for blocking: false" do
+      thread = Thread.new do
+        fiber = Fiber.new(blocking: false) { @method.call }
+        blocking = fiber.resume
+
+        blocking.should == false
+      end
+
+      thread.join
+    end
+  end
+end
diff --git a/spec/ruby/core/fiber/shared/resume.rb b/spec/ruby/core/fiber/shared/resume.rb
new file mode 100644
index 0000000000..ff4bb72c73
--- /dev/null
+++ b/spec/ruby/core/fiber/shared/resume.rb
@@ -0,0 +1,58 @@
+describe :fiber_resume, shared: true do
+  it "can be invoked from the root Fiber" do
+    fiber = Fiber.new { :fiber }
+    fiber.send(@method).should == :fiber
+  end
+
+  it "raises a FiberError if invoked from a different Thread" do
+    fiber = Fiber.new { 42 }
+    Thread.new do
+      -> {
+        fiber.send(@method)
+      }.should.raise(FiberError)
+    end.join
+
+    # Check the Fiber can still be used
+    fiber.send(@method).should == 42
+  end
+
+  it "passes control to the beginning of the block on first invocation" do
+    invoked = false
+    fiber = Fiber.new { invoked = true }
+    fiber.send(@method)
+    invoked.should == true
+  end
+
+  it "returns the last value encountered on first invocation" do
+    fiber = Fiber.new { 1+1; true }
+    fiber.send(@method).should == true
+  end
+
+  it "runs until the end of the block" do
+    obj = mock('obj')
+    obj.should_receive(:do).once
+    fiber = Fiber.new { 1 + 2; a = "glark"; obj.do }
+    fiber.send(@method)
+  end
+
+  it "accepts any number of arguments" do
+    fiber = Fiber.new { |a| }
+    -> { fiber.send(@method, *(1..10).to_a) }.should_not.raise
+  end
+
+  it "raises a FiberError if the Fiber is dead" do
+    fiber = Fiber.new { true }
+    fiber.send(@method)
+    -> { fiber.send(@method) }.should.raise(FiberError)
+  end
+
+  it "raises a LocalJumpError if the block includes a return statement" do
+    fiber = Fiber.new { return; }
+    -> { fiber.send(@method) }.should.raise(LocalJumpError)
+  end
+
+  it "raises a LocalJumpError if the block includes a break statement" do
+    fiber = Fiber.new { break; }
+    -> { fiber.send(@method) }.should.raise(LocalJumpError)
+  end
+end
diff --git a/spec/ruby/core/fiber/shared/scheduler.rb b/spec/ruby/core/fiber/shared/scheduler.rb
new file mode 100644
index 0000000000..04bdded53a
--- /dev/null
+++ b/spec/ruby/core/fiber/shared/scheduler.rb
@@ -0,0 +1,51 @@
+describe :scheduler, shared: true do
+  it "validates the scheduler for required methods" do
+    required_methods = [:block, :unblock, :kernel_sleep, :io_wait]
+    required_methods.each do |missing_method|
+      scheduler = Object.new
+      required_methods.difference([missing_method]).each do |method|
+        scheduler.define_singleton_method(method) {}
+      end
+      -> {
+        suppress_warning { Fiber.set_scheduler(scheduler) }
+      }.should.raise(ArgumentError, /Scheduler must implement ##{missing_method}/)
+    end
+  end
+
+  it "can set and get the scheduler" do
+    required_methods = [:block, :unblock, :kernel_sleep, :io_wait]
+    scheduler = Object.new
+    required_methods.each do |method|
+      scheduler.define_singleton_method(method) {}
+    end
+    suppress_warning { Fiber.set_scheduler(scheduler) }
+    Fiber.scheduler.should == scheduler
+  end
+
+  it "returns the scheduler after setting it" do
+    required_methods = [:block, :unblock, :kernel_sleep, :io_wait]
+    scheduler = Object.new
+    required_methods.each do |method|
+      scheduler.define_singleton_method(method) {}
+    end
+    result = suppress_warning { Fiber.set_scheduler(scheduler) }
+    result.should == scheduler
+  end
+
+  it "can remove the scheduler" do
+    required_methods = [:block, :unblock, :kernel_sleep, :io_wait]
+    scheduler = Object.new
+    required_methods.each do |method|
+      scheduler.define_singleton_method(method) {}
+    end
+    suppress_warning { Fiber.set_scheduler(scheduler) }
+    Fiber.set_scheduler(nil)
+    Fiber.scheduler.should == nil
+  end
+
+  it "can assign a nil scheduler multiple times" do
+    Fiber.set_scheduler(nil)
+    Fiber.set_scheduler(nil)
+    Fiber.scheduler.should == nil
+  end
+end
diff --git a/spec/ruby/core/fiber/storage_spec.rb b/spec/ruby/core/fiber/storage_spec.rb
new file mode 100644
index 0000000000..a3f6bf9cad
--- /dev/null
+++ b/spec/ruby/core/fiber/storage_spec.rb
@@ -0,0 +1,177 @@
+require_relative '../../spec_helper'
+
+describe "Fiber.new(storage:)" do
+  it "creates a Fiber with the given storage" do
+    storage = {life: 42}
+    fiber = Fiber.new(storage: storage) { Fiber.current.storage }
+    fiber.resume.should == storage
+  end
+
+  it "creates a fiber with lazily initialized storage" do
+    Fiber.new(storage: nil) { Fiber[:x] = 10; Fiber.current.storage }.resume.should == {x: 10}
+  end
+
+  it "creates a fiber by inheriting the storage of the parent fiber" do
+    fiber = Fiber.new(storage: {life: 42}) do
+      Fiber.new { Fiber.current.storage }.resume
+    end
+    fiber.resume.should == {life: 42}
+  end
+
+  it "cannot create a fiber with non-hash storage" do
+    -> { Fiber.new(storage: 42) {} }.should.raise(TypeError)
+  end
+
+  it "cannot create a fiber with a frozen hash as storage" do
+    -> { Fiber.new(storage: {life: 43}.freeze) {} }.should.raise(FrozenError)
+  end
+
+  it "cannot create a fiber with a storage hash with non-symbol keys" do
+    -> { Fiber.new(storage: {life: 43, Object.new => 44}) {} }.should.raise(TypeError)
+  end
+end
+
+describe "Fiber#storage" do
+  it "cannot be accessed from a different fiber" do
+    f = Fiber.new(storage: {life: 42}) { nil }
+    -> {
+      f.storage
+    }.should.raise(ArgumentError, /Fiber storage can only be accessed from the Fiber it belongs to/)
+  end
+end
+
+describe "Fiber#storage=" do
+  it "can clear the storage of the fiber" do
+    fiber = Fiber.new(storage: {life: 42}) do
+      Fiber.current.storage = nil
+      Fiber[:x] = 10
+      Fiber.current.storage
+    end
+    fiber.resume.should == {x: 10}
+  end
+
+  it "can set the storage of the fiber" do
+    fiber = Fiber.new(storage: {life: 42}) do
+      Fiber.current.storage = {life: 43}
+      Fiber.current.storage
+    end
+    fiber.resume.should == {life: 43}
+  end
+
+  it "can't set the storage of the fiber to non-hash" do
+    -> { Fiber.current.storage = 42 }.should.raise(TypeError)
+  end
+
+  it "can't set the storage of the fiber to a frozen hash" do
+    -> { Fiber.current.storage = {life: 43}.freeze }.should.raise(FrozenError)
+  end
+
+  it "can't set the storage of the fiber to a hash with non-symbol keys" do
+    -> { Fiber.current.storage = {life: 43, Object.new => 44} }.should.raise(TypeError)
+  end
+end
+
+describe "Fiber.[]" do
+  it "returns the value of the given key in the storage of the current fiber" do
+    Fiber.new(storage: {life: 42}) { Fiber[:life] }.resume.should == 42
+  end
+
+  it "returns nil if the key is not present in the storage of the current fiber" do
+    Fiber.new(storage: {life: 42}) { Fiber[:death] }.resume.should == nil
+  end
+
+  it "returns nil if the current fiber has no storage" do
+    Fiber.new { Fiber[:life] }.resume.should == nil
+  end
+
+  it "can use dynamically defined keys" do
+    key = :"#{self.class.name}#.#{self.object_id}"
+    Fiber.new { Fiber[key] = 42; Fiber[key] }.resume.should == 42
+  end
+
+  it "can't use invalid keys" do
+    invalid_keys = [Object.new, 12]
+    invalid_keys.each do |key|
+      -> { Fiber[key] }.should.raise(TypeError)
+    end
+  end
+
+  ruby_bug "#20978", ""..."3.4" do
+    it "can use keys as strings" do
+      key = Object.new
+      def key.to_str; "Foo"; end
+      Fiber.new { Fiber[key] = 42; Fiber["Foo"] }.resume.should == 42
+    end
+
+    it "converts a String key into a Symbol" do
+      Fiber.new { Fiber["key"] = 42; Fiber[:key] }.resume.should == 42
+      Fiber.new { Fiber[:key] = 42; Fiber["key"] }.resume.should == 42
+    end
+
+    it "can use any object that responds to #to_str as a key" do
+      key = mock("key")
+      key.should_receive(:to_str).twice.and_return("key")
+      Fiber.new { Fiber[key] = 42; Fiber[key] }.resume.should == 42
+    end
+  end
+
+  it "does not call #to_sym on the key" do
+    key = mock("key")
+    key.should_not_receive(:to_sym)
+    -> { Fiber[key] }.should.raise(TypeError)
+  end
+
+  it "can access the storage of the parent fiber" do
+    f = Fiber.new(storage: {life: 42}) do
+      Fiber.new { Fiber[:life] }.resume
+    end
+    f.resume.should == 42
+  end
+
+  it "can't access the storage of the fiber with non-symbol keys" do
+    -> { Fiber[Object.new] }.should.raise(TypeError)
+  end
+end
+
+describe "Fiber.[]=" do
+  it "sets the value of the given key in the storage of the current fiber" do
+    Fiber.new(storage: {life: 42}) { Fiber[:life] = 43; Fiber[:life] }.resume.should == 43
+  end
+
+  it "sets the value of the given key in the storage of the current fiber" do
+    Fiber.new(storage: {life: 42}) { Fiber[:death] = 43; Fiber[:death] }.resume.should == 43
+  end
+
+  it "sets the value of the given key in the storage of the current fiber" do
+    Fiber.new { Fiber[:life] = 43; Fiber[:life] }.resume.should == 43
+  end
+
+  it "does not overwrite the storage of the parent fiber" do
+    f = Fiber.new(storage: {life: 42}) do
+      Fiber.yield Fiber.new { Fiber[:life] = 43; Fiber[:life] }.resume
+      Fiber[:life]
+    end
+    f.resume.should == 43 # Value of the inner fiber
+    f.resume.should == 42 # Value of the outer fiber
+  end
+
+  it "can't access the storage of the fiber with non-symbol keys" do
+    -> { Fiber[Object.new] = 44 }.should.raise(TypeError)
+  end
+
+  it "deletes the fiber storage key when assigning nil" do
+    Fiber.new(storage: {life: 42}) {
+      Fiber[:life] = nil
+      Fiber.current.storage
+    }.resume.should == {}
+  end
+end
+
+describe "Thread.new" do
+  it "creates a thread with the storage of the current fiber" do
+    fiber = Fiber.new(storage: {life: 42}) do
+      Thread.new { Fiber.current.storage }.value
+    end
+    fiber.resume.should == {life: 42}
+  end
+end
diff --git a/spec/ruby/core/fiber/transfer_spec.rb b/spec/ruby/core/fiber/transfer_spec.rb
new file mode 100644
index 0000000000..d8737aeeb3
--- /dev/null
+++ b/spec/ruby/core/fiber/transfer_spec.rb
@@ -0,0 +1,84 @@
+require_relative '../../spec_helper'
+require_relative 'shared/resume'
+
+describe "Fiber#transfer" do
+  it_behaves_like :fiber_resume, :transfer
+end
+
+describe "Fiber#transfer" do
+  it "transfers control from one Fiber to another when called from a Fiber" do
+    fiber1 = Fiber.new { :fiber1 }
+    fiber2 = Fiber.new { fiber1.transfer; :fiber2 }
+    fiber2.resume.should == :fiber2
+  end
+
+  it "returns to the root Fiber when finished" do
+    f1 = Fiber.new { :fiber_1 }
+    f2 = Fiber.new { f1.transfer; :fiber_2 }
+
+    f2.transfer.should == :fiber_1
+    f2.transfer.should == :fiber_2
+  end
+
+  it "can be invoked from the same Fiber it transfers control to" do
+    states = []
+    fiber = Fiber.new { states << :start; fiber.transfer; states << :end }
+    fiber.transfer
+    states.should == [:start, :end]
+
+    states = []
+    fiber = Fiber.new { states << :start; fiber.transfer; states << :end }
+    fiber.resume
+    states.should == [:start, :end]
+  end
+
+  it "can not transfer control to a Fiber that has suspended by Fiber.yield" do
+    states = []
+    fiber1 = Fiber.new { states << :fiber1 }
+    fiber2 = Fiber.new { states << :fiber2_start; Fiber.yield fiber1.transfer; states << :fiber2_end}
+    fiber2.resume.should == [:fiber2_start, :fiber1]
+    -> { fiber2.transfer }.should.raise(FiberError)
+  end
+
+  it "raises a FiberError when transferring to a Fiber which resumes itself" do
+    fiber = Fiber.new { fiber.resume }
+    -> { fiber.transfer }.should.raise(FiberError)
+  end
+
+  it "works if Fibers in different Threads each transfer to a Fiber in the same Thread" do
+    # This catches a bug where Fibers are running on a thread-pool
+    # and Fibers from a different Ruby Thread reuse the same native thread.
+    # Caching the Ruby Thread based on the native thread is not correct in that case,
+    # and the check for "fiber called across threads" in Fiber#transfer
+    # might be incorrect based on that.
+    2.times do
+      Thread.new do
+        io_fiber = Fiber.new do |calling_fiber|
+          calling_fiber.transfer
+        end
+        io_fiber.transfer(Fiber.current)
+        value = Object.new
+        io_fiber.transfer(value).should.equal? value
+      end.join
+    end
+  end
+
+  it "transfers control between a non-main thread's root fiber to a child fiber and back again" do
+    states = []
+    thread = Thread.new do
+      f1 = Fiber.new do |f0|
+        states << 0
+        value2 = f0.transfer(1)
+        states << value2
+        3
+      end
+
+      value1 = f1.transfer(Fiber.current)
+      states << value1
+      value3 = f1.transfer(2)
+      states << value3
+    end
+    thread.join
+    states.should == [0, 1, 2, 3]
+  end
+end
diff --git a/spec/ruby/core/fiber/yield_spec.rb b/spec/ruby/core/fiber/yield_spec.rb
index b010912c87..12ec6ebcef 100644
--- a/spec/ruby/core/fiber/yield_spec.rb
+++ b/spec/ruby/core/fiber/yield_spec.rb
@@ -18,7 +18,7 @@ describe "Fiber.yield" do
 
   it "returns nil to the caller if given no arguments" do
     fiber = Fiber.new { true; Fiber.yield; true }
-    fiber.resume.should be_nil
+    fiber.resume.should == nil
     fiber.resume
   end
 
@@ -44,6 +44,6 @@ describe "Fiber.yield" do
   end
 
   it "raises a FiberError if called from the root Fiber" do
-    ->{ Fiber.yield }.should raise_error(FiberError)
+    ->{ Fiber.yield }.should.raise(FiberError)
   end
 end
diff --git a/spec/ruby/core/file/absolute_path_spec.rb b/spec/ruby/core/file/absolute_path_spec.rb
index 52839cf1cc..fc12985a75 100644
--- a/spec/ruby/core/file/absolute_path_spec.rb
+++ b/spec/ruby/core/file/absolute_path_spec.rb
@@ -1,54 +1,52 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.7" do
-  describe "File.absolute_path?" do
-    before :each do
-      @abs = File.expand_path(__FILE__)
-    end
+describe "File.absolute_path?" do
+  before :each do
+    @abs = File.expand_path(__FILE__)
+  end
 
-    it "returns true if it's an absolute pathname" do
-      File.absolute_path?(@abs).should be_true
-    end
+  it "returns true if it's an absolute pathname" do
+    File.absolute_path?(@abs).should == true
+  end
 
-    it "returns false if it's a relative path" do
-      File.absolute_path?(File.basename(__FILE__)).should be_false
-    end
+  it "returns false if it's a relative path" do
+    File.absolute_path?(File.basename(__FILE__)).should == false
+  end
 
-    it "returns false if it's a tricky relative path" do
-      File.absolute_path?("C:foo\\bar").should be_false
-    end
+  it "returns false if it's a tricky relative path" do
+    File.absolute_path?("C:foo\\bar").should == false
+  end
 
-    it "does not expand '~' to a home directory." do
-      File.absolute_path?('~').should be_false
-    end
+  it "does not expand '~' to a home directory." do
+    File.absolute_path?('~').should == false
+  end
 
-    it "does not expand '~user' to a home directory." do
-      path = File.dirname(@abs)
-      Dir.chdir(path) do
-        File.absolute_path?('~user').should be_false
-      end
+  it "does not expand '~user' to a home directory." do
+    path = File.dirname(@abs)
+    Dir.chdir(path) do
+      File.absolute_path?('~user').should == false
     end
+  end
 
-    it "calls #to_path on its argument" do
-      mock = mock_to_path(File.expand_path(__FILE__))
+  it "calls #to_path on its argument" do
+    mock = mock_to_path(File.expand_path(__FILE__))
 
-      File.absolute_path?(mock).should be_true
-    end
+    File.absolute_path?(mock).should == true
+  end
 
-    platform_is_not :windows do
-      it "takes into consideration the platform's root" do
-        File.absolute_path?("C:\\foo\\bar").should be_false
-        File.absolute_path?("C:/foo/bar").should be_false
-        File.absolute_path?("/foo/bar\\baz").should be_true
-      end
+  platform_is_not :windows do
+    it "takes into consideration the platform's root" do
+      File.absolute_path?("C:\\foo\\bar").should == false
+      File.absolute_path?("C:/foo/bar").should == false
+      File.absolute_path?("/foo/bar\\baz").should == true
     end
+  end
 
-    platform_is :windows do
-      it "takes into consideration the platform path separator(s)" do
-        File.absolute_path?("C:\\foo\\bar").should be_true
-        File.absolute_path?("C:/foo/bar").should be_true
-        File.absolute_path?("/foo/bar\\baz").should be_false
-      end
+  platform_is :windows do
+    it "takes into consideration the platform path separator(s)" do
+      File.absolute_path?("C:\\foo\\bar").should == true
+      File.absolute_path?("C:/foo/bar").should == true
+      File.absolute_path?("/foo/bar\\baz").should == false
     end
   end
 end
@@ -73,6 +71,12 @@ describe "File.absolute_path" do
     File.absolute_path('~').should_not == File.expand_path('~')
   end
 
+  platform_is_not :windows do
+    it "does not expand '~' when given dir argument" do
+      File.absolute_path('~', '/').should == '/~'
+    end
+  end
+
   it "does not expand '~user' to a home directory." do
     path = File.dirname(@abs)
     Dir.chdir(path) do
@@ -81,7 +85,7 @@ describe "File.absolute_path" do
   end
 
   it "accepts a second argument of a directory from which to resolve the path" do
-    File.absolute_path(__FILE__, File.dirname(__FILE__)).should == @abs
+    File.absolute_path(__FILE__, __dir__).should == @abs
   end
 
   it "calls #to_path on its argument" do
diff --git a/spec/ruby/core/file/atime_spec.rb b/spec/ruby/core/file/atime_spec.rb
index 02e8412722..5c6c110eec 100644
--- a/spec/ruby/core/file/atime_spec.rb
+++ b/spec/ruby/core/file/atime_spec.rb
@@ -12,25 +12,30 @@ describe "File.atime" do
 
   it "returns the last access time for the named file as a Time object" do
     File.atime(@file)
-    File.atime(@file).should be_kind_of(Time)
-  end
-
-  guard -> { platform_is :linux or (platform_is :windows and ruby_version_is '2.5') } do
-    ## NOTE also that some Linux systems disable atime (e.g. via mount params) for better filesystem speed.
-    it "returns the last access time for the named file with microseconds" do
-      supports_subseconds = Integer(`stat -c%x '#{__FILE__}'`[/\.(\d+)/, 1], 10)
-      if supports_subseconds != 0
-        expected_time = Time.at(Time.now.to_i + 0.123456)
-        File.utime expected_time, 0, @file
-        File.atime(@file).usec.should == expected_time.usec
-      else
-        File.atime(__FILE__).usec.should == 0
+    File.atime(@file).should.is_a?(Time)
+  end
+
+  platform_is :linux, :windows do
+    unless ENV.key?('TRAVIS') # https://bugs.ruby-lang.org/issues/17926
+      ## NOTE also that some Linux systems disable atime (e.g. via mount params) for better filesystem speed.
+      it "returns the last access time for the named file with microseconds" do
+        supports_subseconds = Integer(`stat -c%x '#{__FILE__}'`[/\.(\d{1,6})/, 1], 10)
+        if supports_subseconds != 0
+          expected_time = Time.at(Time.now.to_i + 0.123456)
+          File.utime expected_time, 0, @file
+          File.atime(@file).usec.should == expected_time.usec
+        else
+          File.atime(__FILE__).usec.should == 0
+        end
+      rescue Errno::ENOENT => e
+        # Native Windows don't have stat command.
+        skip e.message
       end
     end
   end
 
   it "raises an Errno::ENOENT exception if the file is not found" do
-    -> { File.atime('a_fake_file') }.should raise_error(Errno::ENOENT)
+    -> { File.atime('a_fake_file') }.should.raise(Errno::ENOENT)
   end
 
   it "accepts an object that has a #to_path method" do
@@ -50,6 +55,6 @@ describe "File#atime" do
 
   it "returns the last access time to self" do
     @file.atime
-    @file.atime.should be_kind_of(Time)
+    @file.atime.should.is_a?(Time)
   end
 end
diff --git a/spec/ruby/core/file/basename_spec.rb b/spec/ruby/core/file/basename_spec.rb
index 6d7e432086..77afe5c22f 100644
--- a/spec/ruby/core/file/basename_spec.rb
+++ b/spec/ruby/core/file/basename_spec.rb
@@ -42,7 +42,7 @@ describe "File.basename" do
   end
 
   it "returns an string" do
-    File.basename("foo").should be_kind_of(String)
+    File.basename("foo").should.is_a?(String)
   end
 
   it "returns the basename for unix format" do
@@ -105,10 +105,10 @@ describe "File.basename" do
   end
 
   it "raises a TypeError if the arguments are not String types" do
-    -> { File.basename(nil)          }.should raise_error(TypeError)
-    -> { File.basename(1)            }.should raise_error(TypeError)
-    -> { File.basename("bar.txt", 1) }.should raise_error(TypeError)
-    -> { File.basename(true)         }.should raise_error(TypeError)
+    -> { File.basename(nil)          }.should.raise(TypeError)
+    -> { File.basename(1)            }.should.raise(TypeError)
+    -> { File.basename("bar.txt", 1) }.should.raise(TypeError)
+    -> { File.basename(true)         }.should.raise(TypeError)
   end
 
   it "accepts an object that has a #to_path method" do
@@ -116,7 +116,7 @@ describe "File.basename" do
   end
 
   it "raises an ArgumentError if passed more than two arguments" do
-    -> { File.basename('bar.txt', '.txt', '.txt') }.should raise_error(ArgumentError)
+    -> { File.basename('bar.txt', '.txt', '.txt') }.should.raise(ArgumentError)
   end
 
   # specific to MS Windows
@@ -151,8 +151,30 @@ describe "File.basename" do
       File.basename("c:\\bar.txt", ".*").should == "bar"
       File.basename("c:\\bar.txt.exe", ".*").should == "bar.txt"
     end
+
+    it "handles Shift JIS 0x5C (\\) as second byte of a multi-byte sequence" do
+      # dir\fileソname.txt
+      path = "dir\\file\x83\x5cname.txt".b.force_encoding(Encoding::SHIFT_JIS)
+      path.valid_encoding?.should == true
+      File.basename(path).should == "file\x83\x5cname.txt".b.force_encoding(Encoding::SHIFT_JIS)
+    end
+  end
+
+  it "rejects strings encoded with non ASCII-compatible encodings" do
+    Encoding.list.reject(&:ascii_compatible?).reject(&:dummy?).each do |enc|
+      path = "/foo/bar".encode(enc)
+
+      -> {
+        File.basename(path)
+      }.should.raise(Encoding::CompatibilityError)
+    end
   end
 
+  it "works with all ASCII-compatible encodings" do
+    Encoding.list.select(&:ascii_compatible?).each do |enc|
+      File.basename("/foo/bar".encode(enc)).should == "bar".encode(enc)
+    end
+  end
 
   it "returns the extension for a multibyte filename" do
     File.basename('/path/Офис.m4a').should == "Офис.m4a"
@@ -164,5 +186,20 @@ describe "File.basename" do
     basename.encoding.should == Encoding::Windows_1250
   end
 
+  it "returns a new unfrozen String" do
+    exts = [nil, '.rb', '.*', '.txt']
+    ['foo.rb','//', '/test/', 'test'].each do |example|
+      exts.each do |ext|
+        original = example.freeze
+        result = if ext
+                   File.basename(original, ext)
+                 else
+                   File.basename(original)
+                 end
+        result.should_not.equal?(original)
+        result.frozen?.should == false
+      end
+    end
+  end
 
 end
diff --git a/spec/ruby/core/file/birthtime_spec.rb b/spec/ruby/core/file/birthtime_spec.rb
index 755601df64..039fd7572c 100644
--- a/spec/ruby/core/file/birthtime_spec.rb
+++ b/spec/ruby/core/file/birthtime_spec.rb
@@ -1,60 +1,56 @@
 require_relative '../../spec_helper'
 
-describe "File.birthtime" do
-  before :each do
-    @file = __FILE__
-  end
+platform_is :windows, :darwin, :freebsd, :netbsd, :linux do
+  not_implemented_messages = [
+    "birthtime() function is unimplemented", # unsupported OS/version
+    "birthtime is unimplemented",            # unsupported filesystem
+  ]
+
+  describe "File.birthtime" do
+    before :each do
+      @file = __FILE__
+    end
 
-  after :each do
-    @file = nil
-  end
+    after :each do
+      @file = nil
+    end
 
-  platform_is :windows, :darwin, :freebsd, :netbsd do
     it "returns the birth time for the named file as a Time object" do
       File.birthtime(@file)
-      File.birthtime(@file).should be_kind_of(Time)
+      File.birthtime(@file).should.is_a?(Time)
+    rescue NotImplementedError => e
+      e.message.should.start_with?(*not_implemented_messages)
     end
 
     it "accepts an object that has a #to_path method" do
+      File.birthtime(@file) # Avoid to failure of mock object with old Kernel and glibc
       File.birthtime(mock_to_path(@file))
+    rescue NotImplementedError => e
+      e.message.should.start_with?(*not_implemented_messages)
     end
 
     it "raises an Errno::ENOENT exception if the file is not found" do
-      -> { File.birthtime('bogus') }.should raise_error(Errno::ENOENT)
+      -> { File.birthtime('bogus') }.should.raise(Errno::ENOENT)
+    rescue NotImplementedError => e
+      e.message.should.start_with?(*not_implemented_messages)
     end
   end
 
-  platform_is :openbsd do
-    it "raises an NotImplementedError" do
-      -> { File.birthtime(@file) }.should raise_error(NotImplementedError)
+  describe "File#birthtime" do
+    before :each do
+      @file = File.open(__FILE__)
     end
-  end
-
-  # TODO: depends on Linux kernel version
-end
 
-describe "File#birthtime" do
-  before :each do
-    @file = File.open(__FILE__)
-  end
-
-  after :each do
-    @file.close
-    @file = nil
-  end
+    after :each do
+      @file.close
+      @file = nil
+    end
 
-  platform_is :windows, :darwin, :freebsd, :netbsd do
     it "returns the birth time for self" do
       @file.birthtime
-      @file.birthtime.should be_kind_of(Time)
+      @file.birthtime.should.is_a?(Time)
+    rescue NotImplementedError => e
+      e.message.should.start_with?(*not_implemented_messages)
     end
   end
-
-  platform_is :openbsd do
-    it "raises an NotImplementedError" do
-      -> { @file.birthtime }.should raise_error(NotImplementedError)
-    end
-  end
-
-  # TODO: depends on Linux kernel version
 end
diff --git a/spec/ruby/core/file/chmod_spec.rb b/spec/ruby/core/file/chmod_spec.rb
index 86171691f6..e0fd10ceb1 100644
--- a/spec/ruby/core/file/chmod_spec.rb
+++ b/spec/ruby/core/file/chmod_spec.rb
@@ -16,8 +16,8 @@ describe "File#chmod" do
   end
 
   it "raises RangeError with too large values" do
-    -> { @file.chmod(2**64) }.should raise_error(RangeError)
-    -> { @file.chmod(-2**63 - 1) }.should raise_error(RangeError)
+    -> { @file.chmod(2**64) }.should.raise(RangeError)
+    -> { @file.chmod(-2**63 - 1) }.should.raise(RangeError)
   end
 
   it "invokes to_int on non-integer argument" do
@@ -97,22 +97,22 @@ describe "File.chmod" do
   end
 
   it "raises RangeError with too large values" do
-    -> { File.chmod(2**64, @file) }.should raise_error(RangeError)
-    -> { File.chmod(-2**63 - 1, @file) }.should raise_error(RangeError)
+    -> { File.chmod(2**64, @file) }.should.raise(RangeError)
+    -> { File.chmod(-2**63 - 1, @file) }.should.raise(RangeError)
   end
 
   it "accepts an object that has a #to_path method" do
     File.chmod(0, mock_to_path(@file))
   end
 
-  it "throws a TypeError if the given path is not coercable into a string" do
-    -> { File.chmod(0, []) }.should raise_error(TypeError)
+  it "throws a TypeError if the given path is not coercible into a string" do
+    -> { File.chmod(0, []) }.should.raise(TypeError)
   end
 
   it "raises an error for a non existent path" do
     -> {
       File.chmod(0644, "#{@file}.not.existing")
-    }.should raise_error(Errno::ENOENT)
+    }.should.raise(Errno::ENOENT)
   end
 
   it "invokes to_int on non-integer argument" do
diff --git a/spec/ruby/core/file/chown_spec.rb b/spec/ruby/core/file/chown_spec.rb
index 8cc8f0d04b..3353aafc70 100644
--- a/spec/ruby/core/file/chown_spec.rb
+++ b/spec/ruby/core/file/chown_spec.rb
@@ -68,7 +68,7 @@ describe "File.chown" do
     it "raises an error for a non existent path" do
       -> {
         File.chown(nil, nil, "#{@fname}_not_existing")
-      }.should raise_error(Errno::ENOENT)
+      }.should.raise(Errno::ENOENT)
     end
   end
 
@@ -78,15 +78,15 @@ describe "File.chown" do
 end
 
 describe "File#chown" do
-    before :each do
-      @fname = tmp('file_chown_test')
-      @file = File.open(@fname, 'w')
-    end
+  before :each do
+    @fname = tmp('file_chown_test')
+    @file = File.open(@fname, 'w')
+  end
 
-    after :each do
-      @file.close unless @file.closed?
-      rm_r @fname
-    end
+  after :each do
+    @file.close unless @file.closed?
+    rm_r @fname
+  end
 
   as_superuser do
     platform_is :windows do
diff --git a/spec/ruby/core/file/constants/constants_spec.rb b/spec/ruby/core/file/constants/constants_spec.rb
index 86946822c5..9d9c1c3b25 100644
--- a/spec/ruby/core/file/constants/constants_spec.rb
+++ b/spec/ruby/core/file/constants/constants_spec.rb
@@ -4,10 +4,10 @@ require_relative '../../../spec_helper'
   "FNM_DOTMATCH", "FNM_EXTGLOB", "FNM_NOESCAPE", "FNM_PATHNAME",
   "FNM_SYSCASE", "LOCK_EX", "LOCK_NB", "LOCK_SH",
   "LOCK_UN", "NONBLOCK", "RDONLY",
-  "RDWR", "TRUNC", "WRONLY"].each do |const|
+  "RDWR", "TRUNC", "WRONLY", "SHARE_DELETE"].each do |const|
   describe "File::Constants::#{const}" do
     it "is defined" do
-      File::Constants.const_defined?(const).should be_true
+      File::Constants.const_defined?(const).should == true
     end
   end
 end
@@ -15,7 +15,7 @@ end
 platform_is :windows do
   describe "File::Constants::BINARY" do
     it "is defined" do
-      File::Constants.const_defined?(:BINARY).should be_true
+      File::Constants.const_defined?(:BINARY).should == true
     end
   end
 end
@@ -24,7 +24,7 @@ platform_is_not :windows do
   ["NOCTTY", "SYNC"].each do |const|
     describe "File::Constants::#{const}" do
       it "is defined" do
-        File::Constants.const_defined?(const).should be_true
+        File::Constants.const_defined?(const).should == true
       end
     end
   end
diff --git a/spec/ruby/core/file/ctime_spec.rb b/spec/ruby/core/file/ctime_spec.rb
index 68a9fa43cb..cf37d1f4ee 100644
--- a/spec/ruby/core/file/ctime_spec.rb
+++ b/spec/ruby/core/file/ctime_spec.rb
@@ -11,17 +11,20 @@ describe "File.ctime" do
 
   it "returns the change time for the named file (the time at which directory information about the file was changed, not the file itself)." do
     File.ctime(@file)
-    File.ctime(@file).should be_kind_of(Time)
+    File.ctime(@file).should.is_a?(Time)
   end
 
-  guard -> { platform_is :linux or (platform_is :windows and ruby_version_is '2.5') } do
+  platform_is :linux, :windows do
     it "returns the change time for the named file (the time at which directory information about the file was changed, not the file itself) with microseconds." do
-      supports_subseconds = Integer(`stat -c%z '#{__FILE__}'`[/\.(\d+)/, 1], 10)
+      supports_subseconds = Integer(`stat -c%z '#{__FILE__}'`[/\.(\d{1,6})/, 1], 10)
       if supports_subseconds != 0
         File.ctime(__FILE__).usec.should > 0
       else
         File.ctime(__FILE__).usec.should == 0
       end
+    rescue Errno::ENOENT => e
+      # Windows don't have stat command.
+      skip e.message
     end
   end
 
@@ -30,7 +33,7 @@ describe "File.ctime" do
   end
 
   it "raises an Errno::ENOENT exception if the file is not found" do
-    -> { File.ctime('bogus') }.should raise_error(Errno::ENOENT)
+    -> { File.ctime('bogus') }.should.raise(Errno::ENOENT)
   end
 end
 
@@ -46,6 +49,6 @@ describe "File#ctime" do
 
   it "returns the change time for the named file (the time at which directory information about the file was changed, not the file itself)." do
     @file.ctime
-    @file.ctime.should be_kind_of(Time)
+    @file.ctime.should.is_a?(Time)
   end
 end
diff --git a/spec/ruby/core/file/dirname_spec.rb b/spec/ruby/core/file/dirname_spec.rb
index 2ef04a7b64..855148a684 100644
--- a/spec/ruby/core/file/dirname_spec.rb
+++ b/spec/ruby/core/file/dirname_spec.rb
@@ -11,8 +11,37 @@ describe "File.dirname" do
     File.dirname('/foo/foo').should == '/foo'
   end
 
+  context "when level is passed" do
+    it "returns all the components of filename except the last parts by the level" do
+      File.dirname('/home/jason', 2).should == '/'
+      File.dirname('/home/jason/poot.txt', 2).should == '/home'
+    end
+
+    it "returns the same String if the level is 0" do
+      File.dirname('poot.txt', 0).should == 'poot.txt'
+      File.dirname('/', 0).should == '/'
+    end
+
+    it "raises ArgumentError if the level is negative" do
+      -> {
+        File.dirname('/home/jason', -1)
+      }.should.raise(ArgumentError, "negative level: -1")
+    end
+
+    it "returns '/' when level exceeds the number of segments in the path" do
+      File.dirname("/home/jason", 100).should == '/'
+    end
+
+    it "calls #to_int if passed not numeric value" do
+      object = Object.new
+      def object.to_int; 2; end
+
+      File.dirname("/a/b/c/d", object).should == '/a/b'
+    end
+  end
+
   it "returns a String" do
-    File.dirname("foo").should be_kind_of(String)
+    File.dirname("foo").should.is_a?(String)
   end
 
   it "does not modify its argument" do
@@ -34,22 +63,48 @@ describe "File.dirname" do
   end
 
   it "returns all the components of filename except the last one (edge cases on all platforms)" do
-      File.dirname("").should == "."
-      File.dirname(".").should == "."
-      File.dirname("./").should == "."
-      File.dirname("./b/./").should == "./b"
-      File.dirname("..").should == "."
-      File.dirname("../").should == "."
-      File.dirname("/").should == "/"
-      File.dirname("/.").should == "/"
-      File.dirname("/foo/").should == "/"
-      File.dirname("/foo/.").should == "/foo"
-      File.dirname("/foo/./").should == "/foo"
-      File.dirname("/foo/../.").should == "/foo/.."
-      File.dirname("foo/../").should == "foo"
+    File.dirname("").should == "."
+    File.dirname(".").should == "."
+    File.dirname("./").should == "."
+    File.dirname("./b/./").should == "./b"
+    File.dirname("..").should == "."
+    File.dirname("../").should == "."
+    File.dirname("/").should == "/"
+    File.dirname("/.").should == "/"
+    File.dirname("/foo/").should == "/"
+    File.dirname("/foo/.").should == "/foo"
+    File.dirname("/foo/./").should == "/foo"
+    File.dirname("/foo/../.").should == "/foo/.."
+    File.dirname("foo/../").should == "foo"
+  end
+
+  it "rejects strings encoded with non ASCII-compatible encodings" do
+    Encoding.list.reject(&:ascii_compatible?).reject(&:dummy?).each do |enc|
+      path = "/foo/bar".encode(enc)
+      -> {
+        File.dirname(path)
+      }.should.raise(Encoding::CompatibilityError)
+    end
+  end
+
+  it "works with all ASCII-compatible encodings" do
+    Encoding.list.select(&:ascii_compatible?).each do |enc|
+      File.dirname("/foo/bar".encode(enc)).should == "/foo".encode(enc)
+    end
+  end
+
+  it "handles Shift JIS 0x5C (\\) as second byte of a multi-byte sequence" do
+    # dir/fileソname.txt
+    path = "dir/file\x83\x5cname.txt".b.force_encoding(Encoding::SHIFT_JIS)
+    path.valid_encoding?.should == true
+    File.dirname(path).should == "dir"
   end
 
   platform_is_not :windows do
+    it "ignores repeated leading / (edge cases on non-windows)" do
+      File.dirname("/////foo/bar/").should == "/foo"
+    end
+
     it "returns all the components of filename except the last one (edge cases on non-windows)" do
       File.dirname('/////').should == '/'
       File.dirname("//foo//").should == "/"
@@ -65,6 +120,13 @@ describe "File.dirname" do
       File.dirname("//foo//").should == "//foo"
       File.dirname('/////').should == '//'
     end
+
+    it "handles Shift JIS 0x5C (\\) as second byte of a multi-byte sequence (windows)" do
+      # dir\fileソname.txt
+      path = "dir\\file\x83\x5cname.txt".b.force_encoding(Encoding::SHIFT_JIS)
+      path.valid_encoding?.should == true
+      File.dirname(path).should == "dir"
+    end
   end
 
   it "accepts an object that has a #to_path method" do
@@ -72,10 +134,10 @@ describe "File.dirname" do
   end
 
   it "raises a TypeError if not passed a String type" do
-    -> { File.dirname(nil)   }.should raise_error(TypeError)
-    -> { File.dirname(0)     }.should raise_error(TypeError)
-    -> { File.dirname(true)  }.should raise_error(TypeError)
-    -> { File.dirname(false) }.should raise_error(TypeError)
+    -> { File.dirname(nil)   }.should.raise(TypeError)
+    -> { File.dirname(0)     }.should.raise(TypeError)
+    -> { File.dirname(true)  }.should.raise(TypeError)
+    -> { File.dirname(false) }.should.raise(TypeError)
   end
 
   # Windows specific tests
diff --git a/spec/ruby/core/file/empty_spec.rb b/spec/ruby/core/file/empty_spec.rb
index 77f132303e..e8c9941676 100644
--- a/spec/ruby/core/file/empty_spec.rb
+++ b/spec/ruby/core/file/empty_spec.rb
@@ -4,10 +4,4 @@ require_relative '../../shared/file/zero'
 describe "File.empty?" do
   it_behaves_like :file_zero, :empty?, File
   it_behaves_like :file_zero_missing, :empty?, File
-
-  platform_is :solaris do
-    it "returns false for /dev/null" do
-      File.empty?('/dev/null').should == true
-    end
-  end
 end
diff --git a/spec/ruby/core/file/exist_spec.rb b/spec/ruby/core/file/exist_spec.rb
index ddb5febcba..b5600e5b07 100644
--- a/spec/ruby/core/file/exist_spec.rb
+++ b/spec/ruby/core/file/exist_spec.rb
@@ -4,3 +4,9 @@ require_relative '../../shared/file/exist'
 describe "File.exist?" do
   it_behaves_like :file_exist, :exist?, File
 end
+
+describe "File.exists?" do
+  it "has been removed" do
+    File.should_not.respond_to?(:exists?)
+  end
+end
diff --git a/spec/ruby/core/file/exists_spec.rb b/spec/ruby/core/file/exists_spec.rb
deleted file mode 100644
index 31d0e4dd1e..0000000000
--- a/spec/ruby/core/file/exists_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative '../../shared/file/exist'
-
-describe "File.exists?" do
-  it_behaves_like :file_exist, :exists?, File
-end
diff --git a/spec/ruby/core/file/expand_path_spec.rb b/spec/ruby/core/file/expand_path_spec.rb
index 88078645ab..160494f145 100644
--- a/spec/ruby/core/file/expand_path_spec.rb
+++ b/spec/ruby/core/file/expand_path_spec.rb
@@ -92,7 +92,7 @@ describe "File.expand_path" do
     end
 
     it "raises an ArgumentError if the path is not valid" do
-      -> { File.expand_path("~a_not_existing_user") }.should raise_error(ArgumentError)
+      -> { File.expand_path("~a_not_existing_user") }.should.raise(ArgumentError)
     end
 
     it "expands ~ENV['USER'] to the user's home directory" do
@@ -117,9 +117,9 @@ describe "File.expand_path" do
   end
 
   it "raises a TypeError if not passed a String type" do
-    -> { File.expand_path(1)    }.should raise_error(TypeError)
-    -> { File.expand_path(nil)  }.should raise_error(TypeError)
-    -> { File.expand_path(true) }.should raise_error(TypeError)
+    -> { File.expand_path(1)    }.should.raise(TypeError)
+    -> { File.expand_path(nil)  }.should.raise(TypeError)
+    -> { File.expand_path(true) }.should.raise(TypeError)
   end
 
   platform_is_not :windows do
@@ -137,11 +137,11 @@ describe "File.expand_path" do
   it "returns a String in the same encoding as the argument" do
     Encoding.default_external = Encoding::SHIFT_JIS
 
-    path = "./a".force_encoding Encoding::CP1251
-    File.expand_path(path).encoding.should equal(Encoding::CP1251)
+    path = "./a".dup.force_encoding Encoding::CP1251
+    File.expand_path(path).encoding.should.equal?(Encoding::CP1251)
 
     weird_path = [222, 173, 190, 175].pack('C*')
-    File.expand_path(weird_path).encoding.should equal(Encoding::BINARY)
+    File.expand_path(weird_path).encoding.should.equal?(Encoding::BINARY)
   end
 
   platform_is_not :windows do
@@ -159,7 +159,7 @@ describe "File.expand_path" do
   platform_is_not :windows do
     it "raises an Encoding::CompatibilityError if the external encoding is not compatible" do
       Encoding.default_external = Encoding::UTF_16BE
-      -> { File.expand_path("./a") }.should raise_error(Encoding::CompatibilityError)
+      -> { File.expand_path("./a") }.should.raise(Encoding::CompatibilityError)
     end
   end
 
@@ -179,7 +179,7 @@ describe "File.expand_path" do
     str = FileSpecs::SubString.new "./a/b/../c"
     path = File.expand_path(str, @base)
     path.should == "#{@base}/a/c"
-    path.should be_an_instance_of(String)
+    path.should.instance_of?(String)
   end
 end
 
@@ -203,9 +203,9 @@ platform_is_not :windows do
 
     it "does not return a frozen string" do
       home = "/rubyspec_home"
-      File.expand_path('~').frozen?.should == false
-      File.expand_path('~', '/tmp/gumby/ddd').frozen?.should == false
-      File.expand_path('~/a', '/tmp/gumby/ddd').frozen?.should == false
+      File.expand_path('~').should_not.frozen?
+      File.expand_path('~', '/tmp/gumby/ddd').should_not.frozen?
+      File.expand_path('~/a', '/tmp/gumby/ddd').should_not.frozen?
     end
   end
 
@@ -244,7 +244,7 @@ platform_is_not :windows do
 
     it "raises an ArgumentError when passed '~' if HOME == ''" do
       ENV["HOME"] = ""
-      -> { File.expand_path("~") }.should raise_error(ArgumentError)
+      -> { File.expand_path("~") }.should.raise(ArgumentError)
     end
   end
 
@@ -259,7 +259,7 @@ platform_is_not :windows do
 
     it "raises an ArgumentError" do
       ENV["HOME"] = "non-absolute"
-      -> { File.expand_path("~") }.should raise_error(ArgumentError, 'non-absolute home')
+      -> { File.expand_path("~") }.should.raise(ArgumentError, 'non-absolute home')
     end
   end
 end
diff --git a/spec/ruby/core/file/extname_spec.rb b/spec/ruby/core/file/extname_spec.rb
index 358690b44a..995d0ea31a 100644
--- a/spec/ruby/core/file/extname_spec.rb
+++ b/spec/ruby/core/file/extname_spec.rb
@@ -2,7 +2,7 @@
 require_relative '../../spec_helper'
 
 describe "File.extname" do
-  it "returns the extension (the portion of file name in path after the period)." do
+  it "returns the extension (the portion of file name in path after the period)" do
     File.extname("foo.rb").should == ".rb"
     File.extname("/foo/bar.rb").should == ".rb"
     File.extname("/foo.rb/bar.c").should == ".c"
@@ -12,7 +12,17 @@ describe "File.extname" do
     File.extname(".app.conf").should == ".conf"
   end
 
-  it "returns the extension (the portion of file name in path after the period).(edge cases)" do
+  it "returns unfrozen strings" do
+    File.extname("foo.rb").frozen?.should == false
+    File.extname("/foo/bar.rb").frozen?.should == false
+    File.extname("/foo.rb/bar.c").frozen?.should == false
+    File.extname("bar").frozen?.should == false
+    File.extname(".bashrc").frozen?.should == false
+    File.extname("/foo.bar/baz").frozen?.should == false
+    File.extname(".app.conf").frozen?.should == false
+  end
+
+  it "returns the extension for edge cases" do
     File.extname("").should ==  ""
     File.extname(".").should ==  ""
     File.extname("/").should ==  ""
@@ -20,8 +30,22 @@ describe "File.extname" do
     File.extname("..").should ==  ""
     File.extname("...").should ==  ""
     File.extname("....").should ==  ""
-    File.extname(".foo.").should ==  ""
-    File.extname("foo.").should ==  ""
+  end
+
+  describe "for a filename ending with a dot" do
+    platform_is :windows do
+      it "returns ''" do
+        File.extname(".foo.").should == ""
+        File.extname("foo.").should == ""
+      end
+    end
+
+    platform_is_not :windows do
+      it "returns '.'" do
+        File.extname(".foo.").should == "."
+        File.extname("foo.").should == "."
+      end
+    end
   end
 
   it "returns only the last extension of a file with several dots" do
@@ -33,15 +57,15 @@ describe "File.extname" do
   end
 
   it "raises a TypeError if not passed a String type" do
-    -> { File.extname(nil)   }.should raise_error(TypeError)
-    -> { File.extname(0)     }.should raise_error(TypeError)
-    -> { File.extname(true)  }.should raise_error(TypeError)
-    -> { File.extname(false) }.should raise_error(TypeError)
+    -> { File.extname(nil)   }.should.raise(TypeError)
+    -> { File.extname(0)     }.should.raise(TypeError)
+    -> { File.extname(true)  }.should.raise(TypeError)
+    -> { File.extname(false) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if not passed one argument" do
-    -> { File.extname }.should raise_error(ArgumentError)
-    -> { File.extname("foo.bar", "foo.baz") }.should raise_error(ArgumentError)
+    -> { File.extname }.should.raise(ArgumentError)
+    -> { File.extname("foo.bar", "foo.baz") }.should.raise(ArgumentError)
   end
 
 
diff --git a/spec/ruby/core/file/flock_spec.rb b/spec/ruby/core/file/flock_spec.rb
index 751e99d994..23ddf89ed8 100644
--- a/spec/ruby/core/file/flock_spec.rb
+++ b/spec/ruby/core/file/flock_spec.rb
@@ -30,7 +30,7 @@ describe "File#flock" do
   it "returns false if trying to lock an exclusively locked file" do
     @file.flock File::LOCK_EX
 
-    ruby_exe(<<-END_OF_CODE, escape: true).should == "false"
+    ruby_exe(<<-END_OF_CODE).should == "false"
       File.open('#{@name}', "w") do |f2|
         print f2.flock(File::LOCK_EX | File::LOCK_NB).to_s
       end
@@ -40,7 +40,7 @@ describe "File#flock" do
   it "blocks if trying to lock an exclusively locked file" do
     @file.flock File::LOCK_EX
 
-    out = ruby_exe(<<-END_OF_CODE, escape: true)
+    out = ruby_exe(<<-END_OF_CODE)
       running = false
 
       t = Thread.new do
@@ -72,35 +72,3 @@ describe "File#flock" do
     end
   end
 end
-
-platform_is :solaris do
-  describe "File#flock on Solaris" do
-    before :each do
-      @name = tmp("flock_test")
-      touch(@name)
-
-      @read_file = File.open @name, "r"
-      @write_file = File.open @name, "w"
-    end
-
-    after :each do
-      @read_file.flock File::LOCK_UN
-      @read_file.close
-      @write_file.flock File::LOCK_UN
-      @write_file.close
-      rm_r @name
-    end
-
-    it "fails with EBADF acquiring exclusive lock on read-only File" do
-      -> do
-        @read_file.flock File::LOCK_EX
-      end.should raise_error(Errno::EBADF)
-    end
-
-    it "fails with EBADF acquiring shared lock on read-only File" do
-      -> do
-        @write_file.flock File::LOCK_SH
-      end.should raise_error(Errno::EBADF)
-    end
-  end
-end
diff --git a/spec/ruby/core/file/ftype_spec.rb b/spec/ruby/core/file/ftype_spec.rb
index 20e9af7e5f..ab9f76b79b 100644
--- a/spec/ruby/core/file/ftype_spec.rb
+++ b/spec/ruby/core/file/ftype_spec.rb
@@ -7,18 +7,19 @@ describe "File.ftype" do
   end
 
   it "raises ArgumentError if not given exactly one filename" do
-    -> { File.ftype }.should raise_error(ArgumentError)
-    -> { File.ftype('blah', 'bleh') }.should raise_error(ArgumentError)
+    -> { File.ftype }.should.raise(ArgumentError)
+    -> { File.ftype('blah', 'bleh') }.should.raise(ArgumentError)
   end
 
   it "raises Errno::ENOENT if the file is not valid" do
-    l = -> { File.ftype("/#{$$}#{Time.now.to_f}") }
-    l.should raise_error(Errno::ENOENT)
+    -> {
+      File.ftype("/#{$$}#{Time.now.to_f}")
+    }.should.raise(Errno::ENOENT)
   end
 
   it "returns a String" do
     FileSpecs.normal_file do |file|
-      File.ftype(file).should be_kind_of(String)
+      File.ftype(file).should.is_a?(String)
     end
   end
 
@@ -34,6 +35,14 @@ describe "File.ftype" do
     end
   end
 
+  it "uses to_path to convert arguments" do
+    FileSpecs.normal_file do |file|
+      obj = mock('path')
+      obj.should_receive(:to_path).and_return(file)
+      File.ftype(obj).should == 'file'
+    end
+  end
+
   # Both FreeBSD and Windows does not have block devices
   platform_is_not :freebsd, :windows do
     with_block_device do
diff --git a/spec/ruby/core/file/inspect_spec.rb b/spec/ruby/core/file/inspect_spec.rb
index 148e789c62..fe87429e8d 100644
--- a/spec/ruby/core/file/inspect_spec.rb
+++ b/spec/ruby/core/file/inspect_spec.rb
@@ -12,6 +12,6 @@ describe "File#inspect" do
   end
 
   it "returns a String" do
-    @file.inspect.should be_an_instance_of(String)
+    @file.inspect.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/core/file/join_spec.rb b/spec/ruby/core/file/join_spec.rb
index f1eab02de0..0f0911ea31 100644
--- a/spec/ruby/core/file/join_spec.rb
+++ b/spec/ruby/core/file/join_spec.rb
@@ -52,7 +52,7 @@ describe "File.join" do
   it "returns a duplicate string when given a single argument" do
     str = "usr"
     File.join(str).should == str
-    File.join(str).should_not equal(str)
+    File.join(str).should_not.equal?(str)
   end
 
   it "supports any number of arguments" do
@@ -104,15 +104,15 @@ describe "File.join" do
   it "raises an ArgumentError if passed a recursive array" do
     a = ["a"]
     a << a
-    -> { File.join a }.should raise_error(ArgumentError)
+    -> { File.join a }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError exception when args are nil" do
-    -> { File.join nil }.should raise_error(TypeError)
+    -> { File.join nil }.should.raise(TypeError)
   end
 
   it "calls #to_str" do
-    -> { File.join(mock('x')) }.should raise_error(TypeError)
+    -> { File.join(mock('x')) }.should.raise(TypeError)
 
     bin = mock("bin")
     bin.should_receive(:to_str).exactly(:twice).and_return("bin")
@@ -129,11 +129,20 @@ describe "File.join" do
   end
 
   it "calls #to_path" do
-    -> { File.join(mock('x')) }.should raise_error(TypeError)
+    -> { File.join(mock('x')) }.should.raise(TypeError)
 
     bin = mock("bin")
     bin.should_receive(:to_path).exactly(:twice).and_return("bin")
     File.join(bin).should == "bin"
     File.join("usr", bin).should == "usr/bin"
   end
+
+  it "raises errors for null bytes" do
+    -> { File.join("\x00x", "metadata.gz") }.should.raise(ArgumentError) { |e|
+      e.message.should == 'string contains null byte'
+    }
+    -> { File.join("metadata.gz", "\x00x") }.should.raise(ArgumentError) { |e|
+      e.message.should == 'string contains null byte'
+    }
+  end
 end
diff --git a/spec/ruby/core/file/lchmod_spec.rb b/spec/ruby/core/file/lchmod_spec.rb
index 9490459a02..3c44374983 100644
--- a/spec/ruby/core/file/lchmod_spec.rb
+++ b/spec/ruby/core/file/lchmod_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "File.lchmod" do
-  platform_is_not :linux, :windows, :openbsd, :solaris, :aix do
+  platform_is_not :linux, :windows, :openbsd, :aix do
     before :each do
       @fname = tmp('file_chmod_test')
       @lname = @fname + '.lnk'
@@ -20,23 +20,13 @@ describe "File.lchmod" do
       File.chmod(0222, @lname).should == 1
       File.lchmod(0755, @lname).should == 1
 
-      File.lstat(@lname).executable?.should == true
-      File.lstat(@lname).readable?.should == true
-      File.lstat(@lname).writable?.should == true
+      File.lstat(@lname).should.executable?
+      File.lstat(@lname).should.readable?
+      File.lstat(@lname).should.writable?
 
-      File.stat(@lname).executable?.should == false
-      File.stat(@lname).readable?.should == false
-      File.stat(@lname).writable?.should == true
-    end
-  end
-
-  platform_is :linux, :openbsd, :aix do
-    it "returns false from #respond_to?" do
-      File.respond_to?(:lchmod).should be_false
-    end
-
-    it "raises a NotImplementedError when called" do
-      -> { File.lchmod 0 }.should raise_error(NotImplementedError)
+      File.stat(@lname).should_not.executable?
+      File.stat(@lname).should_not.readable?
+      File.stat(@lname).should.writable?
     end
   end
 end
diff --git a/spec/ruby/core/file/link_spec.rb b/spec/ruby/core/file/link_spec.rb
index cc63c76aa3..768ee4b0fa 100644
--- a/spec/ruby/core/file/link_spec.rb
+++ b/spec/ruby/core/file/link_spec.rb
@@ -13,7 +13,7 @@ describe "File.link" do
     rm_r @link, @file
   end
 
-  platform_is_not :windows do
+  platform_is_not :windows, :android do
     it "link a file with another" do
       File.link(@file, @link).should == 0
       File.should.exist?(@link)
@@ -22,18 +22,18 @@ describe "File.link" do
 
     it "raises an Errno::EEXIST if the target already exists" do
       File.link(@file, @link)
-      -> { File.link(@file, @link) }.should raise_error(Errno::EEXIST)
+      -> { File.link(@file, @link) }.should.raise(Errno::EEXIST)
     end
 
     it "raises an ArgumentError if not passed two arguments" do
-      -> { File.link                      }.should raise_error(ArgumentError)
-      -> { File.link(@file)               }.should raise_error(ArgumentError)
-      -> { File.link(@file, @link, @file) }.should raise_error(ArgumentError)
+      -> { File.link                      }.should.raise(ArgumentError)
+      -> { File.link(@file)               }.should.raise(ArgumentError)
+      -> { File.link(@file, @link, @file) }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if not passed String types" do
-      -> { File.link(@file, nil) }.should raise_error(TypeError)
-      -> { File.link(@file, 1)   }.should raise_error(TypeError)
+      -> { File.link(@file, nil) }.should.raise(TypeError)
+      -> { File.link(@file, 1)   }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/file/lstat_spec.rb b/spec/ruby/core/file/lstat_spec.rb
index 918ed02163..a5ea9d15a5 100644
--- a/spec/ruby/core/file/lstat_spec.rb
+++ b/spec/ruby/core/file/lstat_spec.rb
@@ -22,8 +22,8 @@ describe "File.lstat" do
     it "returns a File::Stat object with symlink properties for a symlink" do
       st = File.lstat(@link)
 
-      st.symlink?.should == true
-      st.file?.should == false
+      st.should.symlink?
+      st.should_not.file?
     end
   end
 end
diff --git a/spec/ruby/core/file/lutime_spec.rb b/spec/ruby/core/file/lutime_spec.rb
new file mode 100644
index 0000000000..0f6df42ea3
--- /dev/null
+++ b/spec/ruby/core/file/lutime_spec.rb
@@ -0,0 +1,43 @@
+require_relative '../../spec_helper'
+require_relative 'shared/update_time'
+
+platform_is_not :windows do
+  describe "File.lutime" do
+    it_behaves_like :update_time, :lutime
+  end
+
+  describe "File.lutime" do
+    before :each do
+      @atime = Time.utc(2000)
+      @mtime = Time.utc(2001)
+      @file = tmp("specs_lutime_file")
+      @symlink = tmp("specs_lutime_symlink")
+      touch @file
+      File.symlink(@file, @symlink)
+    end
+
+    after :each do
+      rm_r @file, @symlink
+    end
+
+    it "sets the access and modification time for a regular file" do
+      File.lutime(@atime, @mtime, @file)
+      stat = File.stat(@file)
+      stat.atime.should == @atime
+      stat.mtime.should === @mtime
+    end
+
+    it "sets the access and modification time for a symlink" do
+      original = File.stat(@file)
+
+      File.lutime(@atime, @mtime, @symlink)
+      stat = File.lstat(@symlink)
+      stat.atime.should == @atime
+      stat.mtime.should === @mtime
+
+      file = File.stat(@file)
+      file.atime.should == original.atime
+      file.mtime.should == original.mtime
+    end
+  end
+end
diff --git a/spec/ruby/core/file/mkfifo_spec.rb b/spec/ruby/core/file/mkfifo_spec.rb
index 19298c967c..ce4a67fe31 100644
--- a/spec/ruby/core/file/mkfifo_spec.rb
+++ b/spec/ruby/core/file/mkfifo_spec.rb
@@ -19,13 +19,13 @@ describe "File.mkfifo" do
 
     context "when path passed is not a String value" do
       it "raises a TypeError" do
-        -> { File.mkfifo(:"/tmp/fifo") }.should raise_error(TypeError)
+        -> { File.mkfifo(:"/tmp/fifo") }.should.raise(TypeError)
       end
     end
 
     context "when path does not exist" do
       it "raises an Errno::ENOENT exception" do
-        -> { File.mkfifo("/bogus/path") }.should raise_error(Errno::ENOENT)
+        -> { File.mkfifo("/bogus/path") }.should.raise(Errno::ENOENT)
       end
     end
 
diff --git a/spec/ruby/core/file/mtime_spec.rb b/spec/ruby/core/file/mtime_spec.rb
index 1941e2ff85..d83725e25d 100644
--- a/spec/ruby/core/file/mtime_spec.rb
+++ b/spec/ruby/core/file/mtime_spec.rb
@@ -11,25 +11,30 @@ describe "File.mtime" do
   end
 
   it "returns the modification Time of the file" do
-    File.mtime(@filename).should be_kind_of(Time)
+    File.mtime(@filename).should.is_a?(Time)
     File.mtime(@filename).should be_close(@mtime, TIME_TOLERANCE)
   end
 
-  guard -> { platform_is :linux or (platform_is :windows and ruby_version_is '2.5') } do
-    it "returns the modification Time of the file with microseconds" do
-      supports_subseconds = Integer(`stat -c%y '#{__FILE__}'`[/\.(\d+)/, 1], 10)
-      if supports_subseconds != 0
-        expected_time = Time.at(Time.now.to_i + 0.123456)
-        File.utime 0, expected_time, @filename
-        File.mtime(@filename).usec.should == expected_time.usec
-      else
-        File.mtime(__FILE__).usec.should == 0
+  platform_is :linux, :windows do
+    unless ENV.key?('TRAVIS') # https://bugs.ruby-lang.org/issues/17926
+      it "returns the modification Time of the file with microseconds" do
+        supports_subseconds = Integer(`stat -c%y '#{__FILE__}'`[/\.(\d{1,6})/, 1], 10)
+        if supports_subseconds != 0
+          expected_time = Time.at(Time.now.to_i + 0.123456)
+          File.utime 0, expected_time, @filename
+          File.mtime(@filename).usec.should == expected_time.usec
+        else
+          File.mtime(__FILE__).usec.should == 0
+        end
+      rescue Errno::ENOENT => e
+        # Windows don't have stat command.
+        skip e.message
       end
     end
   end
 
   it "raises an Errno::ENOENT exception if the file is not found" do
-    -> { File.mtime('bogus') }.should raise_error(Errno::ENOENT)
+    -> { File.mtime('bogus') }.should.raise(Errno::ENOENT)
   end
 end
 
@@ -45,7 +50,7 @@ describe "File#mtime" do
   end
 
   it "returns the modification Time of the file" do
-    @f.mtime.should be_kind_of(Time)
+    @f.mtime.should.is_a?(Time)
   end
 
 end
diff --git a/spec/ruby/core/file/new_spec.rb b/spec/ruby/core/file/new_spec.rb
index 004f78503a..4cd2cb5dcb 100644
--- a/spec/ruby/core/file/new_spec.rb
+++ b/spec/ruby/core/file/new_spec.rb
@@ -16,13 +16,13 @@ describe "File.new" do
 
   it "returns a new File with mode string" do
     @fh = File.new(@file, 'w')
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "returns a new File with mode num" do
     @fh = File.new(@file, @flags)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
@@ -30,7 +30,7 @@ describe "File.new" do
     rm_r @file
     File.umask(0011)
     @fh = File.new(@file, @flags, 0755)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     platform_is_not :windows do
       File.stat(@file).mode.to_s(8).should == "100744"
     end
@@ -44,7 +44,7 @@ describe "File.new" do
     rm_r @file
     begin
       f = File.new(@file, "w", 0444)
-      -> { f.puts("test") }.should_not raise_error(IOError)
+      -> { f.puts("test") }.should_not.raise(IOError)
     ensure
       f.close
     end
@@ -74,49 +74,84 @@ describe "File.new" do
     @fh = File.new(@file)
     fh_copy = File.new(@fh.fileno)
     fh_copy.autoclose = false
-    fh_copy.should be_kind_of(File)
+    fh_copy.should.is_a?(File)
+    File.should.exist?(@file)
+  end
+
+  it "returns a new read-only File when mode is not specified" do
+    @fh = File.new(@file)
+
+    -> { @fh.puts("test") }.should.raise(IOError)
+    @fh.read.should == ""
+    File.should.exist?(@file)
+  end
+
+  it "returns a new read-only File when mode is not specified but flags option is present" do
+    @fh = File.new(@file, flags: File::CREAT)
+
+    -> { @fh.puts("test") }.should.raise(IOError)
+    @fh.read.should == ""
     File.should.exist?(@file)
   end
 
   it "creates a new file when use File::EXCL mode" do
     @fh = File.new(@file, File::EXCL)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
-  it "raises an Errorno::EEXIST if the file exists when create a new file with File::CREAT|File::EXCL" do
-    -> { @fh = File.new(@file, File::CREAT|File::EXCL) }.should raise_error(Errno::EEXIST)
+  it "raises an Errno::EEXIST if the file exists when create a new file with File::CREAT|File::EXCL" do
+    -> { @fh = File.new(@file, File::CREAT|File::EXCL) }.should.raise(Errno::EEXIST)
   end
 
   it "creates a new file when use File::WRONLY|File::APPEND mode" do
     @fh = File.new(@file, File::WRONLY|File::APPEND)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "returns a new File when use File::APPEND mode" do
     @fh = File.new(@file, File::APPEND)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "returns a new File when use File::RDONLY|File::APPEND mode" do
     @fh = File.new(@file, File::RDONLY|File::APPEND)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "returns a new File when use File::RDONLY|File::WRONLY mode" do
     @fh = File.new(@file, File::RDONLY|File::WRONLY)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
-
   it "creates a new file when use File::WRONLY|File::TRUNC mode" do
     @fh = File.new(@file, File::WRONLY|File::TRUNC)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
+    File.should.exist?(@file)
+  end
+
+  it "returns a new read-only File when use File::RDONLY|File::CREAT mode" do
+    @fh = File.new(@file, File::RDONLY|File::CREAT)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
+
+    # it's read-only
+    -> { @fh.puts("test") }.should.raise(IOError)
+    @fh.read.should == ""
+  end
+
+  it "returns a new read-only File when use File::CREAT mode" do
+    @fh = File.new(@file, File::CREAT)
+    @fh.should.is_a?(File)
+    File.should.exist?(@file)
+
+    # it's read-only
+    -> { @fh.puts("test") }.should.raise(IOError)
+    @fh.read.should == ""
   end
 
   it "coerces filename using to_str" do
@@ -133,17 +168,43 @@ describe "File.new" do
     File.should.exist?(@file)
   end
 
+  it "accepts options as a keyword argument" do
+    @fh = File.new(@file, 'w', 0755, flags: @flags)
+    @fh.should.is_a?(File)
+    @fh.close
+
+    -> {
+      @fh = File.new(@file, 'w', 0755, {flags: @flags})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 1..3)")
+  end
+
+  it "bitwise-ORs mode and flags option" do
+    -> {
+      @fh = File.new(@file, 'w', flags: File::EXCL)
+    }.should.raise(Errno::EEXIST, /File exists/)
+
+    -> {
+      @fh = File.new(@file, mode: 'w', flags: File::EXCL)
+    }.should.raise(Errno::EEXIST, /File exists/)
+  end
+
+  it "does not use the given block and warns to use File::open" do
+    -> {
+      @fh = File.new(@file) { raise }
+    }.should complain(/warning: File::new\(\) does not take block; use File::open\(\) instead/)
+  end
+
   it "raises a TypeError if the first parameter can't be coerced to a string" do
-    -> { File.new(true) }.should raise_error(TypeError)
-    -> { File.new(false) }.should raise_error(TypeError)
+    -> { File.new(true) }.should.raise(TypeError)
+    -> { File.new(false) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the first parameter is nil" do
-    -> { File.new(nil) }.should raise_error(TypeError)
+    -> { File.new(nil) }.should.raise(TypeError)
   end
 
   it "raises an Errno::EBADF if the first parameter is an invalid file descriptor" do
-    -> { File.new(-1) }.should raise_error(Errno::EBADF)
+    -> { File.new(-1) }.should.raise(Errno::EBADF)
   end
 
   platform_is_not :windows do
@@ -152,7 +213,7 @@ describe "File.new" do
       -> {
         f = File.new(@fh.fileno, @flags)
         f.autoclose = false
-      }.should raise_error(Errno::EINVAL)
+      }.should.raise(Errno::EINVAL)
     end
   end
 
diff --git a/spec/ruby/core/file/open_spec.rb b/spec/ruby/core/file/open_spec.rb
index 93f1972ac6..7318c31636 100644
--- a/spec/ruby/core/file/open_spec.rb
+++ b/spec/ruby/core/file/open_spec.rb
@@ -28,7 +28,7 @@ describe "File.open" do
   describe "with a block" do
     it "does not raise error when file is closed inside the block" do
       @fh = File.open(@file) { |fh| fh.close; fh }
-      @fh.closed?.should == true
+      @fh.should.closed?
     end
 
     it "invokes close on an opened file when exiting the block" do
@@ -40,7 +40,7 @@ describe "File.open" do
     it "propagates non-StandardErrors produced by close" do
       -> {
         File.open(@file, 'r') { |f| FileSpecs.make_closer f, Exception }
-      }.should raise_error(Exception)
+      }.should.raise(Exception)
 
       ScratchPad.recorded.should == [:file_opened, :file_closed]
     end
@@ -48,7 +48,7 @@ describe "File.open" do
     it "propagates StandardErrors produced by close" do
       -> {
         File.open(@file, 'r') { |f| FileSpecs.make_closer f, StandardError }
-      }.should raise_error(StandardError)
+      }.should.raise(StandardError)
 
       ScratchPad.recorded.should == [:file_opened, :file_closed]
     end
@@ -62,13 +62,13 @@ describe "File.open" do
 
   it "opens the file (basic case)" do
     @fh = File.open(@file)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "opens the file with unicode characters" do
     @fh = File.open(@unicode_path, "w")
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@unicode_path)
   end
 
@@ -79,7 +79,7 @@ describe "File.open" do
 
   it "opens with mode string" do
     @fh = File.open(@file, 'w')
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
@@ -90,7 +90,7 @@ describe "File.open" do
 
   it "opens a file with mode num" do
     @fh = File.open(@file, @flags)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
@@ -101,7 +101,7 @@ describe "File.open" do
 
   it "opens a file with mode and permission as nil" do
     @fh = File.open(@file, nil, nil)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
   end
 
   # For this test we delete the file first to reset the perms
@@ -109,7 +109,7 @@ describe "File.open" do
     rm_r @file
     File.umask(0011)
     @fh = File.open(@file, @flags, 0755)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     platform_is_not :windows do
       @fh.lstat.mode.to_s(8).should == "100744"
     end
@@ -161,69 +161,69 @@ describe "File.open" do
     @fh = File.open(@file)
     fh_copy = File.open(@fh.fileno)
     fh_copy.autoclose = false
-    fh_copy.should be_kind_of(File)
+    fh_copy.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "opens a file that no exists when use File::WRONLY mode" do
-    -> { File.open(@nonexistent, File::WRONLY) }.should raise_error(Errno::ENOENT)
+    -> { File.open(@nonexistent, File::WRONLY) }.should.raise(Errno::ENOENT)
   end
 
   it "opens a file that no exists when use File::RDONLY mode" do
-    -> { File.open(@nonexistent, File::RDONLY) }.should raise_error(Errno::ENOENT)
+    -> { File.open(@nonexistent, File::RDONLY) }.should.raise(Errno::ENOENT)
   end
 
   it "opens a file that no exists when use 'r' mode" do
-    -> { File.open(@nonexistent, 'r') }.should raise_error(Errno::ENOENT)
+    -> { File.open(@nonexistent, 'r') }.should.raise(Errno::ENOENT)
   end
 
   it "opens a file that no exists when use File::EXCL mode" do
-    -> { File.open(@nonexistent, File::EXCL) }.should raise_error(Errno::ENOENT)
+    -> { File.open(@nonexistent, File::EXCL) }.should.raise(Errno::ENOENT)
   end
 
   it "opens a file that no exists when use File::NONBLOCK mode" do
-    -> { File.open(@nonexistent, File::NONBLOCK) }.should raise_error(Errno::ENOENT)
+    -> { File.open(@nonexistent, File::NONBLOCK) }.should.raise(Errno::ENOENT)
   end
 
   platform_is_not :openbsd, :windows do
     it "opens a file that no exists when use File::TRUNC mode" do
-      -> { File.open(@nonexistent, File::TRUNC) }.should raise_error(Errno::ENOENT)
+      -> { File.open(@nonexistent, File::TRUNC) }.should.raise(Errno::ENOENT)
     end
   end
 
   platform_is :openbsd, :windows do
     it "does not open a file that does no exists when using File::TRUNC mode" do
-      -> { File.open(@nonexistent, File::TRUNC) }.should raise_error(Errno::EINVAL)
+      -> { File.open(@nonexistent, File::TRUNC) }.should.raise(Errno::EINVAL)
     end
   end
 
   platform_is_not :windows do
     it "opens a file that no exists when use File::NOCTTY mode" do
-      -> { File.open(@nonexistent, File::NOCTTY) }.should raise_error(Errno::ENOENT)
+      -> { File.open(@nonexistent, File::NOCTTY) }.should.raise(Errno::ENOENT)
     end
   end
 
   it "opens a file that no exists when use File::CREAT mode" do
     @fh = File.open(@nonexistent, File::CREAT) { |f| f }
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "opens a file that no exists when use 'a' mode" do
     @fh = File.open(@nonexistent, 'a') { |f| f }
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "opens a file that no exists when use 'w' mode" do
     @fh = File.open(@nonexistent, 'w') { |f| f }
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   # Check the grants associated to the different open modes combinations.
   it "raises an ArgumentError exception when call with an unknown mode" do
-    -> { File.open(@file, "q") }.should raise_error(ArgumentError)
+    -> { File.open(@file, "q") }.should.raise(ArgumentError)
   end
 
   it "can read in a block when call open with RDONLY mode" do
@@ -240,13 +240,13 @@ describe "File.open" do
 
   it "raises an IO exception when write in a block opened with RDONLY mode" do
     File.open(@file, File::RDONLY) do |f|
-      -> { f.puts "writing ..." }.should raise_error(IOError)
+      -> { f.puts "writing ..." }.should.raise(IOError)
     end
   end
 
   it "raises an IO exception when write in a block opened with 'r' mode" do
     File.open(@file, "r") do |f|
-      -> { f.puts "writing ..." }.should raise_error(IOError)
+      -> { f.puts "writing ..." }.should.raise(IOError)
     end
   end
 
@@ -261,7 +261,7 @@ describe "File.open" do
       File.open(@file, File::WRONLY|File::RDONLY ) do |f|
         f.gets.should == nil
       end
-    }.should raise_error(IOError)
+    }.should.raise(IOError)
   end
 
   it "can write in a block when call open with WRONLY mode" do
@@ -278,48 +278,48 @@ describe "File.open" do
 
   it "raises an IOError when read in a block opened with WRONLY mode" do
     File.open(@file, File::WRONLY) do |f|
-      -> { f.gets  }.should raise_error(IOError)
+      -> { f.gets  }.should.raise(IOError)
     end
   end
 
   it "raises an IOError when read in a block opened with 'w' mode" do
     File.open(@file, "w") do |f|
-      -> { f.gets   }.should raise_error(IOError)
+      -> { f.gets   }.should.raise(IOError)
     end
   end
 
   it "raises an IOError when read in a block opened with 'a' mode" do
     File.open(@file, "a") do |f|
-      -> { f.gets  }.should raise_error(IOError)
+      -> { f.gets  }.should.raise(IOError)
     end
   end
 
   it "raises an IOError when read in a block opened with 'a' mode" do
     File.open(@file, "a") do |f|
       f.puts("writing").should == nil
-      -> { f.gets }.should raise_error(IOError)
+      -> { f.gets }.should.raise(IOError)
     end
   end
 
   it "raises an IOError when read in a block opened with 'a' mode" do
     File.open(@file, File::WRONLY|File::APPEND ) do |f|
-      -> { f.gets }.should raise_error(IOError)
+      -> { f.gets }.should.raise(IOError)
     end
   end
 
   it "raises an IOError when read in a block opened with File::WRONLY|File::APPEND mode" do
     File.open(@file, File::WRONLY|File::APPEND ) do |f|
       f.puts("writing").should == nil
-      -> { f.gets }.should raise_error(IOError)
+      -> { f.gets }.should.raise(IOError)
     end
   end
 
-  it "raises an IOError when read in a block opened with File::RDONLY|File::APPEND mode" do
+  it "raises an IOError when write in a block opened with File::RDONLY|File::APPEND mode" do
     -> {
       File.open(@file, File::RDONLY|File::APPEND ) do |f|
         f.puts("writing")
       end
-    }.should raise_error(IOError)
+    }.should.raise(IOError)
   end
 
   it "can read and write in a block when call open with RDWR mode" do
@@ -336,7 +336,7 @@ describe "File.open" do
       File.open(@file, File::EXCL) do |f|
         f.puts("writing").should == nil
       end
-    }.should raise_error(IOError)
+    }.should.raise(IOError)
   end
 
   it "can read in a block when call open with File::EXCL mode" do
@@ -354,17 +354,17 @@ describe "File.open" do
     end
   end
 
-  it "raises an Errorno::EEXIST if the file exists when open with File::CREAT|File::EXCL" do
+  it "raises an Errno::EEXIST if the file exists when open with File::CREAT|File::EXCL" do
     -> {
       File.open(@file, File::CREAT|File::EXCL) do |f|
         f.puts("writing")
       end
-    }.should raise_error(Errno::EEXIST)
+    }.should.raise(Errno::EEXIST)
   end
 
   it "creates a new file when use File::WRONLY|File::APPEND mode" do
     @fh = File.open(@file, File::WRONLY|File::APPEND)
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
@@ -386,7 +386,7 @@ describe "File.open" do
       File.open(@file, File::RDONLY|File::APPEND) do |f|
         f.puts("writing").should == nil
       end
-    }.should raise_error(IOError)
+    }.should.raise(IOError)
   end
 
   platform_is_not :openbsd, :windows do
@@ -407,7 +407,7 @@ describe "File.open" do
     fh1 = File.open(@file, "w")
     begin
       @fh = File.open(@file, File::WRONLY|File::TRUNC)
-      @fh.should be_kind_of(File)
+      @fh.should.is_a?(File)
       File.should.exist?(@file)
     ensure
       fh1.close
@@ -420,15 +420,15 @@ describe "File.open" do
         File.open(@file, File::TRUNC) do |f|
           f.puts("writing")
         end
-      }.should raise_error(IOError)
+      }.should.raise(IOError)
     end
 
-    it "raises an Errorno::EEXIST if the file exists when open with File::RDONLY|File::TRUNC" do
+    it "raises an Errno::EEXIST if the file exists when open with File::RDONLY|File::TRUNC" do
       -> {
         File.open(@file, File::RDONLY|File::TRUNC) do |f|
           f.puts("writing").should == nil
         end
-      }.should raise_error(IOError)
+      }.should.raise(IOError)
     end
   end
 
@@ -438,15 +438,15 @@ describe "File.open" do
         File.open(@file, File::TRUNC) do |f|
           f.puts("writing")
         end
-      }.should raise_error(Errno::EINVAL)
+      }.should.raise(Errno::EINVAL)
     end
 
-    it "raises an Errorno::EEXIST if the file exists when open with File::RDONLY|File::TRUNC" do
+    it "raises an Errno::EEXIST if the file exists when open with File::RDONLY|File::TRUNC" do
       -> {
         File.open(@file, File::RDONLY|File::TRUNC) do |f|
           f.puts("writing").should == nil
         end
-      }.should raise_error(Errno::EINVAL)
+      }.should.raise(Errno::EINVAL)
     end
   end
 
@@ -455,7 +455,7 @@ describe "File.open" do
       it "raises an Errno::EACCES when opening non-permitted file" do
         @fh = File.open(@file, "w")
         @fh.chmod(000)
-        -> { fh1 = File.open(@file); fh1.close }.should raise_error(Errno::EACCES)
+        -> { fh1 = File.open(@file); fh1.close }.should.raise(Errno::EACCES)
       end
     end
   end
@@ -464,19 +464,19 @@ describe "File.open" do
     it "raises an Errno::EACCES when opening read-only file" do
       @fh = File.open(@file, "w")
       @fh.chmod(0444)
-      -> { File.open(@file, "w") }.should raise_error(Errno::EACCES)
+      -> { File.open(@file, "w") }.should.raise(Errno::EACCES)
     end
   end
 
   it "opens a file for binary read" do
     @fh = File.open(@file, "rb")
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
   it "opens a file for binary write" do
     @fh = File.open(@file, "wb")
-    @fh.should be_kind_of(File)
+    @fh.should.is_a?(File)
     File.should.exist?(@file)
   end
 
@@ -485,7 +485,7 @@ describe "File.open" do
     File.size(@file).should > 0
     File.open(@file, "w+") do |f|
       f.pos.should == 0
-      f.eof?.should == true
+      f.should.eof?
     end
     File.size(@file).should == 0
   end
@@ -494,8 +494,16 @@ describe "File.open" do
     File.open(@file, "w") { |f| f.puts "testing" }
     File.size(@file).should > 0
     File.open(@file, "rb+") do |f|
+      f.binmode?.should == true
+      f.external_encoding.should == Encoding::ASCII_8BIT
       f.pos.should == 0
-      f.eof?.should == false
+      f.should_not.eof?
+    end
+    File.open(@file, "r+b") do |f|
+      f.binmode?.should == true
+      f.external_encoding.should == Encoding::ASCII_8BIT
+      f.pos.should == 0
+      f.should_not.eof?
     end
   end
 
@@ -504,7 +512,7 @@ describe "File.open" do
     File.size(@file).should > 0
     File.open(@file, "wb+") do |f|
       f.pos.should == 0
-      f.eof?.should == true
+      f.should.eof?
     end
     File.size(@file).should == 0
   end
@@ -535,21 +543,21 @@ describe "File.open" do
   end
 
   it "raises a TypeError if passed a filename that is not a String or Integer type" do
-    -> { File.open(true)  }.should raise_error(TypeError)
-    -> { File.open(false) }.should raise_error(TypeError)
-    -> { File.open(nil)   }.should raise_error(TypeError)
+    -> { File.open(true)  }.should.raise(TypeError)
+    -> { File.open(false) }.should.raise(TypeError)
+    -> { File.open(nil)   }.should.raise(TypeError)
   end
 
   it "raises a SystemCallError if passed an invalid Integer type" do
-    -> { File.open(-1)    }.should raise_error(SystemCallError)
+    -> { File.open(-1)    }.should.raise(SystemCallError)
   end
 
   it "raises an ArgumentError if passed the wrong number of arguments" do
-    -> { File.open(@file, File::CREAT, 0755, 'test') }.should raise_error(ArgumentError)
+    -> { File.open(@file, File::CREAT, 0755, 'test') }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed an invalid string for mode" do
-    -> { File.open(@file, 'fake') }.should raise_error(ArgumentError)
+    -> { File.open(@file, 'fake') }.should.raise(ArgumentError)
   end
 
   it "defaults external_encoding to BINARY for binary modes" do
@@ -557,9 +565,18 @@ describe "File.open" do
     File.open(@file, 'wb+') {|f| f.external_encoding.should == Encoding::BINARY}
   end
 
+  it "accepts options as a keyword argument" do
+    @fh = File.open(@file, 'w', 0755, flags: File::CREAT)
+    @fh.should.instance_of?(File)
+
+    -> {
+      File.open(@file, 'w', 0755, {flags: File::CREAT})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 1..3)")
+  end
+
   it "uses the second argument as an options Hash" do
     @fh = File.open(@file, mode: "r")
-    @fh.should be_an_instance_of(File)
+    @fh.should.instance_of?(File)
   end
 
   it "calls #to_hash to convert the second argument to a Hash" do
@@ -572,17 +589,17 @@ describe "File.open" do
   it "accepts extra flags as a keyword argument and combine with a string mode" do
     -> {
       File.open(@file, "w", flags: File::EXCL) { }
-    }.should raise_error(Errno::EEXIST)
+    }.should.raise(Errno::EEXIST)
 
     -> {
       File.open(@file, mode: "w", flags: File::EXCL) { }
-    }.should raise_error(Errno::EEXIST)
+    }.should.raise(Errno::EEXIST)
   end
 
   it "accepts extra flags as a keyword argument and combine with an integer mode" do
     -> {
       File.open(@file, File::WRONLY | File::CREAT, flags: File::EXCL) { }
-    }.should raise_error(Errno::EEXIST)
+    }.should.raise(Errno::EEXIST)
   end
 
   platform_is_not :windows do
@@ -623,31 +640,35 @@ describe "File.open" do
     end
   end
 
-  ruby_version_is "2.6" do
-    context "'x' flag" do
-      before :each do
-        @xfile = tmp("x-flag")
-        rm_r @xfile
-      end
+  it "raises ArgumentError if mixing :newline and binary mode" do
+    -> {
+      File.open(@file, "rb", newline: :universal) {}
+    }.should.raise(ArgumentError, "newline decorator with binary mode")
+  end
 
-      after :each do
-        rm_r @xfile
-      end
+  context "'x' flag" do
+    before :each do
+      @xfile = tmp("x-flag")
+      rm_r @xfile
+    end
 
-      it "does nothing if the file doesn't exist" do
-        File.open(@xfile, "wx") { |f| f.write("content") }
-        File.read(@xfile).should == "content"
-      end
+    after :each do
+      rm_r @xfile
+    end
 
-      it "throws a Errno::EEXIST error if the file exists" do
-        touch @xfile
-        -> { File.open(@xfile, "wx") }.should raise_error(Errno::EEXIST)
-      end
+    it "does nothing if the file doesn't exist" do
+      File.open(@xfile, "wx") { |f| f.write("content") }
+      File.read(@xfile).should == "content"
+    end
 
-      it "can't be used with 'r' and 'a' flags" do
-        -> { File.open(@xfile, "rx") }.should raise_error(ArgumentError, 'invalid access mode rx')
-        -> { File.open(@xfile, "ax") }.should raise_error(ArgumentError, 'invalid access mode ax')
-      end
+    it "throws a Errno::EEXIST error if the file exists" do
+      touch @xfile
+      -> { File.open(@xfile, "wx") }.should.raise(Errno::EEXIST)
+    end
+
+    it "can't be used with 'r' and 'a' flags" do
+      -> { File.open(@xfile, "rx") }.should.raise(ArgumentError, 'invalid access mode rx')
+      -> { File.open(@xfile, "ax") }.should.raise(ArgumentError, 'invalid access mode ax')
     end
   end
 end
@@ -667,8 +688,8 @@ describe "File.open when passed a file descriptor" do
 
   it "opens a file" do
     @file = File.open(@fd, "w")
-    @file.should be_an_instance_of(File)
-    @file.fileno.should equal(@fd)
+    @file.should.instance_of?(File)
+    @file.fileno.should.equal?(@fd)
     @file.write @content
     @file.flush
     File.read(@name).should == @content
@@ -676,8 +697,8 @@ describe "File.open when passed a file descriptor" do
 
   it "opens a file when passed a block" do
     @file = File.open(@fd, "w") do |f|
-      f.should be_an_instance_of(File)
-      f.fileno.should equal(@fd)
+      f.should.instance_of?(File)
+      f.fileno.should.equal?(@fd)
       f.write @content
       f
     end
diff --git a/spec/ruby/core/file/path_spec.rb b/spec/ruby/core/file/path_spec.rb
index dfa0c4ec02..ce78dbeede 100644
--- a/spec/ruby/core/file/path_spec.rb
+++ b/spec/ruby/core/file/path_spec.rb
@@ -37,4 +37,45 @@ describe "File.path" do
     path.should_receive(:to_path).and_return("abc")
     File.path(path).should == "abc"
   end
+
+  it "raises TypeError when #to_path result is not a string" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return(nil)
+    -> { File.path(path) }.should.raise TypeError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return(42)
+    -> { File.path(path) }.should.raise TypeError
+  end
+
+  it "raises ArgumentError for string argument contains NUL character" do
+    -> { File.path("\0") }.should.raise ArgumentError
+    -> { File.path("a\0") }.should.raise ArgumentError
+    -> { File.path("a\0c") }.should.raise ArgumentError
+  end
+
+  it "raises ArgumentError when #to_path result contains NUL character" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return("\0")
+    -> { File.path(path) }.should.raise ArgumentError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return("a\0")
+    -> { File.path(path) }.should.raise ArgumentError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return("a\0c")
+    -> { File.path(path) }.should.raise ArgumentError
+  end
+
+  it "raises Encoding::CompatibilityError for ASCII-incompatible string argument" do
+    path = "abc".encode(Encoding::UTF_32BE)
+    -> { File.path(path) }.should.raise Encoding::CompatibilityError
+  end
+
+  it "raises Encoding::CompatibilityError when #to_path result is ASCII-incompatible" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return("abc".encode(Encoding::UTF_32BE))
+    -> { File.path(path) }.should.raise Encoding::CompatibilityError
+  end
 end
diff --git a/spec/ruby/core/file/readlink_spec.rb b/spec/ruby/core/file/readlink_spec.rb
index eb3bfda30e..568692b9b6 100644
--- a/spec/ruby/core/file/readlink_spec.rb
+++ b/spec/ruby/core/file/readlink_spec.rb
@@ -26,12 +26,12 @@ describe "File.readlink" do
 
       it "raises an Errno::ENOENT if there is no such file" do
         # TODO: missing_file
-        -> { File.readlink("/this/surely/doesnt/exist") }.should raise_error(Errno::ENOENT)
+        -> { File.readlink("/this/surely/does/not/exist") }.should.raise(Errno::ENOENT)
       end
 
       it "raises an Errno::EINVAL if called with a normal file" do
         touch @file
-        -> { File.readlink(@file) }.should raise_error(Errno::EINVAL)
+        -> { File.readlink(@file) }.should.raise(Errno::EINVAL)
       end
     end
 
@@ -49,7 +49,7 @@ describe "File.readlink" do
       it "returns the name of the file referenced by the given link" do
         touch @file
         result = File.readlink(@link)
-        result.encoding.should equal Encoding.find('filesystem')
+        result.encoding.should.equal? Encoding.find('filesystem')
         result.should == @file.dup.force_encoding(Encoding.find('filesystem'))
       end
     end
diff --git a/spec/ruby/core/file/realdirpath_spec.rb b/spec/ruby/core/file/realdirpath_spec.rb
index 74053afce3..ecf1e0c6d9 100644
--- a/spec/ruby/core/file/realdirpath_spec.rb
+++ b/spec/ruby/core/file/realdirpath_spec.rb
@@ -61,7 +61,7 @@ platform_is_not :windows do
     it "raises an Errno::ELOOP if the symlink points to itself" do
       File.unlink @link
       File.symlink(@link, @link)
-      -> { File.realdirpath(@link) }.should raise_error(Errno::ELOOP)
+      -> { File.realdirpath(@link) }.should.raise(Errno::ELOOP)
     end
 
     it "returns the real (absolute) pathname if the file is absent" do
@@ -69,7 +69,7 @@ platform_is_not :windows do
     end
 
     it "raises Errno::ENOENT if the directory is absent" do
-      -> { File.realdirpath(@fake_file_in_fake_dir) }.should raise_error(Errno::ENOENT)
+      -> { File.realdirpath(@fake_file_in_fake_dir) }.should.raise(Errno::ENOENT)
     end
 
     it "returns the real (absolute) pathname if the symlink points to an absent file" do
@@ -77,7 +77,7 @@ platform_is_not :windows do
     end
 
     it "raises Errno::ENOENT if the symlink points to an absent directory" do
-      -> { File.realdirpath(@fake_link_to_fake_dir) }.should raise_error(Errno::ENOENT)
+      -> { File.realdirpath(@fake_link_to_fake_dir) }.should.raise(Errno::ENOENT)
     end
   end
 end
diff --git a/spec/ruby/core/file/realpath_spec.rb b/spec/ruby/core/file/realpath_spec.rb
index 0c5d19287a..ccb981eff1 100644
--- a/spec/ruby/core/file/realpath_spec.rb
+++ b/spec/ruby/core/file/realpath_spec.rb
@@ -54,18 +54,28 @@ platform_is_not :windows do
       File.realpath(@relative_symlink).should == @file
     end
 
+    it "removes the file element when going one level up" do
+      File.realpath('../', @file).should == @real_dir
+    end
+
     it "raises an Errno::ELOOP if the symlink points to itself" do
       File.unlink @link
       File.symlink(@link, @link)
-      -> { File.realpath(@link) }.should raise_error(Errno::ELOOP)
+      -> { File.realpath(@link) }.should.raise(Errno::ELOOP)
     end
 
     it "raises Errno::ENOENT if the file is absent" do
-      -> { File.realpath(@fake_file) }.should raise_error(Errno::ENOENT)
+      -> { File.realpath(@fake_file) }.should.raise(Errno::ENOENT)
     end
 
     it "raises Errno::ENOENT if the symlink points to an absent file" do
-      -> { File.realpath(@fake_link) }.should raise_error(Errno::ENOENT)
+      -> { File.realpath(@fake_link) }.should.raise(Errno::ENOENT)
+    end
+
+    it "converts the argument with #to_path" do
+      path = mock("path")
+      path.should_receive(:to_path).and_return(__FILE__)
+      File.realpath(path).should == File.realpath(__FILE__ )
     end
   end
 end
diff --git a/spec/ruby/core/file/rename_spec.rb b/spec/ruby/core/file/rename_spec.rb
index f2c18d4905..70ea669a68 100644
--- a/spec/ruby/core/file/rename_spec.rb
+++ b/spec/ruby/core/file/rename_spec.rb
@@ -23,15 +23,15 @@ describe "File.rename" do
 
   it "raises an Errno::ENOENT if the source does not exist" do
     rm_r @old
-    -> { File.rename(@old, @new) }.should raise_error(Errno::ENOENT)
+    -> { File.rename(@old, @new) }.should.raise(Errno::ENOENT)
   end
 
   it "raises an ArgumentError if not passed two arguments" do
-    -> { File.rename        }.should raise_error(ArgumentError)
-    -> { File.rename(@file) }.should raise_error(ArgumentError)
+    -> { File.rename        }.should.raise(ArgumentError)
+    -> { File.rename(@file) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError if not passed String types" do
-    -> { File.rename(1, 2)  }.should raise_error(TypeError)
+    -> { File.rename(1, 2)  }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/file/setuid_spec.rb b/spec/ruby/core/file/setuid_spec.rb
index 281ef01ab9..9e5e86df61 100644
--- a/spec/ruby/core/file/setuid_spec.rb
+++ b/spec/ruby/core/file/setuid_spec.rb
@@ -26,10 +26,6 @@ describe "File.setuid?" do
 
   platform_is_not :windows do
     it "returns true when the gid bit is set" do
-      platform_is :solaris do
-        # Solaris requires execute bit before setting suid
-        system "chmod u+x #{@name}"
-      end
       system "chmod u+s #{@name}"
 
       File.setuid?(@name).should == true
diff --git a/spec/ruby/core/file/shared/fnmatch.rb b/spec/ruby/core/file/shared/fnmatch.rb
index a8488fd30a..b9140d027d 100644
--- a/spec/ruby/core/file/shared/fnmatch.rb
+++ b/spec/ruby/core/file/shared/fnmatch.rb
@@ -75,6 +75,14 @@ describe :file_fnmatch, shared: true do
     File.send(@method, 'c*t', 'c/a/b/t').should == true
   end
 
+  it "does not match unterminated range of characters" do
+    File.send(@method, 'abc[de', 'abcd').should == false
+  end
+
+  it "does not match unterminated range of characters as a literal" do
+    File.send(@method, 'abc[de', 'abc[de').should == false
+  end
+
   it "matches ranges of characters using bracket expression (e.g. [a-z])" do
     File.send(@method, 'ca[a-z]', 'cat').should == true
   end
@@ -94,6 +102,7 @@ describe :file_fnmatch, shared: true do
 
   it "matches ranges of characters using exclusive bracket expression (e.g. [^t] or [!t])" do
     File.send(@method, 'ca[^t]', 'cat').should == false
+    File.send(@method, 'ca[^t]', 'cas').should == true
     File.send(@method, 'ca[!t]', 'cat').should == false
   end
 
@@ -117,6 +126,13 @@ describe :file_fnmatch, shared: true do
     end
   end
 
+  it "matches wildcard with characters when flags includes FNM_PATHNAME" do
+    File.send(@method, '*a', 'aa', File::FNM_PATHNAME).should == true
+    File.send(@method, 'a*', 'aa', File::FNM_PATHNAME).should == true
+    File.send(@method, 'a*', 'aaa', File::FNM_PATHNAME).should == true
+    File.send(@method, '*a', 'aaa', File::FNM_PATHNAME).should == true
+  end
+
   it "does not match '/' characters with ? or * when flags includes FNM_PATHNAME" do
     File.send(@method, '?', '/', File::FNM_PATHNAME).should == false
     File.send(@method, '*', '/', File::FNM_PATHNAME).should == false
@@ -151,15 +167,25 @@ describe :file_fnmatch, shared: true do
   end
 
   it "does not match leading periods in filenames with wildcards by default" do
-    File.send(@method, '*', '.profile').should == false
-    File.send(@method, '*', 'home/.profile').should == true
-    File.send(@method, '*/*', 'home/.profile').should == true
-    File.send(@method, '*/*', 'dave/.profile', File::FNM_PATHNAME).should == false
+    File.should_not.send(@method, '*', '.profile')
+    File.should.send(@method, '*', 'home/.profile')
+    File.should.send(@method, '*/*', 'home/.profile')
+    File.should_not.send(@method, '*/*', 'dave/.profile', File::FNM_PATHNAME)
   end
 
-  it "matches patterns with leading periods to dotfiles by default" do
+  it "matches patterns with leading periods to dotfiles" do
     File.send(@method, '.*', '.profile').should == true
+    File.send(@method, '.*', '.profile', File::FNM_PATHNAME).should == true
     File.send(@method, ".*file", "nondotfile").should == false
+    File.send(@method, ".*file", "nondotfile", File::FNM_PATHNAME).should == false
+  end
+
+  it "does not match directories with leading periods by default with FNM_PATHNAME" do
+    File.send(@method, '.*', '.directory/nondotfile', File::FNM_PATHNAME).should == false
+    File.send(@method, '.*', '.directory/.profile', File::FNM_PATHNAME).should == false
+    File.send(@method, '.*', 'foo/.directory/nondotfile', File::FNM_PATHNAME).should == false
+    File.send(@method, '.*', 'foo/.directory/.profile', File::FNM_PATHNAME).should == false
+    File.send(@method, '**/.dotfile', '.dotsubdir/.dotfile', File::FNM_PATHNAME).should == false
   end
 
   it "matches leading periods in filenames when flags includes FNM_DOTMATCH" do
@@ -196,21 +222,48 @@ describe :file_fnmatch, shared: true do
 
   it "returns false if '/' in pattern do not match '/' in path when flags includes FNM_PATHNAME" do
     pattern = '*/*'
-    File.send(@method, pattern, 'dave/.profile', File::FNM_PATHNAME).should be_false
+    File.send(@method, pattern, 'dave/.profile', File::FNM_PATHNAME).should == false
 
     pattern = '**/foo'
-    File.send(@method, pattern, 'a/.b/c/foo', File::FNM_PATHNAME).should be_false
+    File.send(@method, pattern, 'a/.b/c/foo', File::FNM_PATHNAME).should == false
   end
 
   it "returns true if '/' in pattern match '/' in path when flags includes FNM_PATHNAME" do
     pattern = '*/*'
-    File.send(@method, pattern, 'dave/.profile', File::FNM_PATHNAME | File::FNM_DOTMATCH).should be_true
+    File.send(@method, pattern, 'dave/.profile', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
 
     pattern = '**/foo'
-    File.send(@method, pattern, 'a/b/c/foo', File::FNM_PATHNAME).should be_true
-    File.send(@method, pattern, '/a/b/c/foo', File::FNM_PATHNAME).should be_true
-    File.send(@method, pattern, 'c:/a/b/c/foo', File::FNM_PATHNAME).should be_true
-    File.send(@method, pattern, 'a/.b/c/foo', File::FNM_PATHNAME | File::FNM_DOTMATCH).should be_true
+    File.send(@method, pattern, 'a/b/c/foo', File::FNM_PATHNAME).should == true
+    File.send(@method, pattern, '/a/b/c/foo', File::FNM_PATHNAME).should == true
+    File.send(@method, pattern, 'c:/a/b/c/foo', File::FNM_PATHNAME).should == true
+    File.send(@method, pattern, 'a/.b/c/foo', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+  end
+
+  it "has special handling for ./ when using * and FNM_PATHNAME" do
+    File.send(@method, './*', '.', File::FNM_PATHNAME).should == false
+    File.send(@method, './*', './', File::FNM_PATHNAME).should == true
+    File.send(@method, './*/', './', File::FNM_PATHNAME).should == false
+    File.send(@method, './**', './', File::FNM_PATHNAME).should == true
+    File.send(@method, './**/', './', File::FNM_PATHNAME).should == true
+    File.send(@method, './*', '.', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == false
+    File.send(@method, './*', './', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+    File.send(@method, './*/', './', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == false
+    File.send(@method, './**', './', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+    File.send(@method, './**/', './', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+  end
+
+  it "matches **/* with FNM_PATHNAME to recurse directories" do
+    File.send(@method, 'nested/**/*', 'nested/subdir', File::FNM_PATHNAME).should == true
+    File.send(@method, 'nested/**/*', 'nested/subdir/file', File::FNM_PATHNAME).should == true
+    File.send(@method, 'nested/**/*', 'nested/.dotsubdir', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+    File.send(@method, 'nested/**/*', 'nested/.dotsubir/.dotfile', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+  end
+
+  it "matches ** with FNM_PATHNAME only in current directory" do
+    File.send(@method, 'nested/**', 'nested/subdir', File::FNM_PATHNAME).should == true
+    File.send(@method, 'nested/**', 'nested/subdir/file', File::FNM_PATHNAME).should == false
+    File.send(@method, 'nested/**', 'nested/.dotsubdir', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == true
+    File.send(@method, 'nested/**', 'nested/.dotsubir/.dotfile', File::FNM_PATHNAME | File::FNM_DOTMATCH).should == false
   end
 
   it "accepts an object that has a #to_path method" do
@@ -218,21 +271,21 @@ describe :file_fnmatch, shared: true do
   end
 
   it "raises a TypeError if the first and second arguments are not string-like" do
-    -> { File.send(@method, nil, nil, 0, 0) }.should raise_error(ArgumentError)
-    -> { File.send(@method, 1, 'some/thing') }.should raise_error(TypeError)
-    -> { File.send(@method, 'some/thing', 1) }.should raise_error(TypeError)
-    -> { File.send(@method, 1, 1) }.should raise_error(TypeError)
+    -> { File.send(@method, nil, nil, 0, 0) }.should.raise(ArgumentError)
+    -> { File.send(@method, 1, 'some/thing') }.should.raise(TypeError)
+    -> { File.send(@method, 'some/thing', 1) }.should.raise(TypeError)
+    -> { File.send(@method, 1, 1) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the third argument is not an Integer" do
-    -> { File.send(@method, "*/place", "path/to/file", "flags") }.should raise_error(TypeError)
-    -> { File.send(@method, "*/place", "path/to/file", nil) }.should raise_error(TypeError)
+    -> { File.send(@method, "*/place", "path/to/file", "flags") }.should.raise(TypeError)
+    -> { File.send(@method, "*/place", "path/to/file", nil) }.should.raise(TypeError)
   end
 
   it "does not raise a TypeError if the third argument can be coerced to an Integer" do
     flags = mock("flags")
     flags.should_receive(:to_int).and_return(10)
-    -> { File.send(@method, "*/place", "path/to/file", flags) }.should_not raise_error
+    -> { File.send(@method, "*/place", "path/to/file", flags) }.should_not.raise
   end
 
   it "matches multibyte characters" do
diff --git a/spec/ruby/core/file/shared/open.rb b/spec/ruby/core/file/shared/open.rb
index 677a82a351..67149235ca 100644
--- a/spec/ruby/core/file/shared/open.rb
+++ b/spec/ruby/core/file/shared/open.rb
@@ -4,7 +4,7 @@ describe :open_directory, shared: true do
   it "opens directories" do
     file = File.send(@method, tmp(""))
     begin
-      file.should be_kind_of(File)
+      file.should.is_a?(File)
     ensure
       file.close
     end
diff --git a/spec/ruby/core/file/shared/path.rb b/spec/ruby/core/file/shared/path.rb
index cfd119f799..6c6f7d4234 100644
--- a/spec/ruby/core/file/shared/path.rb
+++ b/spec/ruby/core/file/shared/path.rb
@@ -1,7 +1,7 @@
 describe :file_path, shared: true do
   before :each do
-    @name = "file_to_path"
-    @path = tmp(@name)
+    @path = tmp("file_to_path")
+    @name = File.basename(@path)
     touch @path
   end
 
@@ -12,7 +12,24 @@ describe :file_path, shared: true do
 
   it "returns a String" do
     @file = File.new @path
-    @file.send(@method).should be_an_instance_of(String)
+    @file.send(@method).should.instance_of?(String)
+  end
+
+  it "returns a different String on every call" do
+    @file = File.new @path
+    path1 = @file.send(@method)
+    path2 = @file.send(@method)
+    path1.should == path2
+    path1.should_not.equal?(path2)
+  end
+
+  it "returns a mutable String" do
+    @file = File.new @path.dup.freeze
+    path = @file.send(@method)
+    path.should == @path
+    path.should_not.frozen?
+    path << "test"
+    @file.send(@method).should == @path
   end
 
   it "calls to_str on argument and returns exact value" do
@@ -50,27 +67,15 @@ describe :file_path, shared: true do
     @file.send(@method).encoding.should == Encoding.find("euc-jp")
   end
 
-  ruby_version_is "2.5" do
-    platform_is :linux do
-      guard -> { defined?(File::TMPFILE) } do
-        before :each do
-          @dir = tmp("tmpfilespec")
-          mkdir_p @dir
-        end
-
-        after :each do
-          rm_r @dir
-        end
+  platform_is :linux do
+    guard -> { defined?(File::TMPFILE) } do
+      before :each do
+        @dir = tmp("tmpfilespec")
+        mkdir_p @dir
+      end
 
-        it "raises IOError if file was opened with File::TMPFILE" do
-          begin
-            File.open(@dir, File::RDWR | File::TMPFILE) do |f|
-              -> { f.send(@method) }.should raise_error(IOError)
-            end
-          rescue Errno::EOPNOTSUPP, Errno::EINVAL, Errno::EISDIR
-            skip "no support from the filesystem"
-          end
-        end
+      after :each do
+        rm_r @dir
       end
     end
   end
diff --git a/spec/ruby/core/file/shared/read.rb b/spec/ruby/core/file/shared/read.rb
index a2d479966d..f60800bb2f 100644
--- a/spec/ruby/core/file/shared/read.rb
+++ b/spec/ruby/core/file/shared/read.rb
@@ -1,15 +1,15 @@
 require_relative '../../dir/fixtures/common'
 
 describe :file_read_directory, shared: true do
-  platform_is :darwin, :linux, :openbsd, :windows do
+  platform_is :darwin, :linux, :freebsd, :openbsd, :windows do
     it "raises an Errno::EISDIR when passed a path that is a directory" do
-      -> { @object.send(@method, ".") }.should raise_error(Errno::EISDIR)
+      -> { @object.send(@method, ".") }.should.raise(Errno::EISDIR)
     end
   end
 
-  platform_is :freebsd, :netbsd do
+  platform_is :netbsd do
     it "does not raises any exception when passed a path that is a directory" do
-      -> { @object.send(@method, ".") }.should_not raise_error
+      -> { @object.send(@method, ".") }.should_not.raise
     end
   end
 end
diff --git a/spec/ruby/core/file/shared/stat.rb b/spec/ruby/core/file/shared/stat.rb
index fdaf97ea61..879a7f11ff 100644
--- a/spec/ruby/core/file/shared/stat.rb
+++ b/spec/ruby/core/file/shared/stat.rb
@@ -10,13 +10,13 @@ describe :file_stat, shared: true do
 
   it "returns a File::Stat object if the given file exists" do
     st = File.send(@method, @file)
-    st.should be_an_instance_of(File::Stat)
+    st.should.instance_of?(File::Stat)
   end
 
   it "returns a File::Stat object when called on an instance of File" do
     File.open(@file) do |f|
       st = f.send(@method)
-      st.should be_an_instance_of(File::Stat)
+      st.should.instance_of?(File::Stat)
     end
   end
 
@@ -27,6 +27,6 @@ describe :file_stat, shared: true do
   it "raises an Errno::ENOENT if the file does not exist" do
     -> {
       File.send(@method, "fake_file")
-    }.should raise_error(Errno::ENOENT)
+    }.should.raise(Errno::ENOENT)
   end
 end
diff --git a/spec/ruby/core/file/shared/unlink.rb b/spec/ruby/core/file/shared/unlink.rb
index e339e93271..0032907ba2 100644
--- a/spec/ruby/core/file/shared/unlink.rb
+++ b/spec/ruby/core/file/shared/unlink.rb
@@ -31,11 +31,11 @@ describe :file_unlink, shared: true do
   end
 
   it "raises a TypeError if not passed a String type" do
-    -> { File.send(@method, 1) }.should raise_error(TypeError)
+    -> { File.send(@method, 1) }.should.raise(TypeError)
   end
 
   it "raises an Errno::ENOENT when the given file doesn't exist" do
-    -> { File.send(@method, 'bogus') }.should raise_error(Errno::ENOENT)
+    -> { File.send(@method, 'bogus') }.should.raise(Errno::ENOENT)
   end
 
   it "coerces a given parameter into a string if possible" do
diff --git a/spec/ruby/core/file/shared/update_time.rb b/spec/ruby/core/file/shared/update_time.rb
new file mode 100644
index 0000000000..3fe7266a00
--- /dev/null
+++ b/spec/ruby/core/file/shared/update_time.rb
@@ -0,0 +1,105 @@
+describe :update_time, shared: true do
+  before :all do
+    @time_is_float = platform_is :windows
+  end
+
+  before :each do
+    @atime = Time.now
+    @mtime = Time.now
+    @file1 = tmp("specs_file_utime1")
+    @file2 = tmp("specs_file_utime2")
+    touch @file1
+    touch @file2
+  end
+
+  after :each do
+    rm_r @file1, @file2
+  end
+
+  it "sets the access and modification time of each file" do
+    File.send(@method, @atime, @mtime, @file1, @file2)
+
+    if @time_is_float
+      File.atime(@file1).should be_close(@atime, 0.0001)
+      File.mtime(@file1).should be_close(@mtime, 0.0001)
+      File.atime(@file2).should be_close(@atime, 0.0001)
+      File.mtime(@file2).should be_close(@mtime, 0.0001)
+    else
+      File.atime(@file1).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
+      File.mtime(@file1).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
+      File.atime(@file2).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
+      File.mtime(@file2).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
+    end
+  end
+
+  it "uses the current times if two nil values are passed" do
+    tn = Time.now
+    File.send(@method, nil, nil, @file1, @file2)
+
+    if @time_is_float
+      File.atime(@file1).should be_close(tn, 0.050)
+      File.mtime(@file1).should be_close(tn, 0.050)
+      File.atime(@file2).should be_close(tn, 0.050)
+      File.mtime(@file2).should be_close(tn, 0.050)
+    else
+      File.atime(@file1).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
+      File.mtime(@file1).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
+      File.atime(@file2).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
+      File.mtime(@file2).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
+    end
+  end
+
+  it "accepts an object that has a #to_path method" do
+    File.send(@method, @atime, @mtime, mock_to_path(@file1), mock_to_path(@file2))
+  end
+
+  it "accepts numeric atime and mtime arguments" do
+    if @time_is_float
+      File.send(@method, @atime.to_f, @mtime.to_f, @file1, @file2)
+
+      File.atime(@file1).should be_close(@atime, 0.0001)
+      File.mtime(@file1).should be_close(@mtime, 0.0001)
+      File.atime(@file2).should be_close(@atime, 0.0001)
+      File.mtime(@file2).should be_close(@mtime, 0.0001)
+    else
+      File.send(@method, @atime.to_i, @mtime.to_i, @file1, @file2)
+
+      File.atime(@file1).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
+      File.mtime(@file1).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
+      File.atime(@file2).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
+      File.mtime(@file2).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
+    end
+  end
+
+  it "may set nanosecond precision" do
+    t = Time.utc(2007, 11, 1, 15, 25, 0, 123456.789r)
+    File.send(@method, t, t, @file1)
+
+    File.atime(@file1).nsec.should.between?(0, 123500000)
+    File.mtime(@file1).nsec.should.between?(0, 123500000)
+  end
+
+  it "returns the number of filenames in the arguments" do
+    File.send(@method, @atime.to_f, @mtime.to_f, @file1, @file2).should == 2
+  end
+
+  platform_is :linux do
+    platform_is pointer_size: 64 do
+      it "allows Time instances in the far future to set mtime and atime (but some filesystems limit it up to 2446-05-10 or 2038-01-19 or 2486-07-02)" do
+        # https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Inode_Timestamps
+        # "Therefore, timestamps should not overflow until May 2446."
+        # https://lwn.net/Articles/804382/
+        # "On-disk timestamps hitting the y2038 limit..."
+        # The problem seems to be being improved, but currently it actually fails on XFS on RHEL8
+        # https://rubyci.org/logs/rubyci.s3.amazonaws.com/rhel8/ruby-master/log/20201112T123004Z.fail.html.gz
+        # Amazon Linux 2023 returns 2486-07-02 in this example
+        # http://rubyci.s3.amazonaws.com/amazon2023/ruby-master/log/20230322T063004Z.fail.html.gz
+        time = Time.at(1<<44)
+        File.send(@method, time, time, @file1)
+
+        [559444, 2486, 2446, 2038].should.include? File.atime(@file1).year
+        [559444, 2486, 2446, 2038].should.include? File.mtime(@file1).year
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/file/size_spec.rb b/spec/ruby/core/file/size_spec.rb
index a2bf408da1..784c18c26e 100644
--- a/spec/ruby/core/file/size_spec.rb
+++ b/spec/ruby/core/file/size_spec.rb
@@ -56,11 +56,11 @@ describe "File#size" do
   end
 
   it "is an instance method" do
-    @file.respond_to?(:size).should be_true
+    @file.respond_to?(:size).should == true
   end
 
-  it "returns the file's size as a Fixnum" do
-    @file.size.should be_an_instance_of(Fixnum)
+  it "returns the file's size as an Integer" do
+    @file.size.should.instance_of?(Integer)
   end
 
   it "returns the file's size in bytes" do
@@ -81,7 +81,7 @@ describe "File#size" do
 
   it "raises an IOError on a closed file" do
     @file.close
-    -> { @file.size }.should raise_error(IOError)
+    -> { @file.size }.should.raise(IOError)
   end
 
   platform_is_not :windows do
diff --git a/spec/ruby/core/file/socket_spec.rb b/spec/ruby/core/file/socket_spec.rb
index 5d12e21f55..d3f4eb013a 100644
--- a/spec/ruby/core/file/socket_spec.rb
+++ b/spec/ruby/core/file/socket_spec.rb
@@ -1,42 +1,10 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/file/socket'
-require 'socket'
 
 describe "File.socket?" do
   it_behaves_like :file_socket, :socket?, File
-end
 
-describe "File.socket?" do
   it "returns false if file does not exist" do
     File.socket?("I_am_a_bogus_file").should == false
   end
-
-  it "returns false if the file is not a socket" do
-    filename = tmp("i_exist")
-    touch(filename)
-
-    File.socket?(filename).should == false
-
-    rm_r filename
-  end
-end
-
-platform_is_not :windows do
-  describe "File.socket?" do
-    before :each do
-      # We need a really short name here.
-      # On Linux the path length is limited to 107, see unix(7).
-      @name = tmp("s")
-      @server = UNIXServer.new @name
-    end
-
-    after :each do
-      @server.close
-      rm_r @name
-    end
-
-    it "returns true if the file is a socket" do
-      File.socket?(@name).should == true
-    end
-  end
 end
diff --git a/spec/ruby/core/file/split_spec.rb b/spec/ruby/core/file/split_spec.rb
index 7b958621b9..e989a6b86e 100644
--- a/spec/ruby/core/file/split_spec.rb
+++ b/spec/ruby/core/file/split_spec.rb
@@ -44,12 +44,12 @@ describe "File.split" do
   end
 
   it "raises an ArgumentError when not passed a single argument" do
-    -> { File.split }.should raise_error(ArgumentError)
-    -> { File.split('string', 'another string') }.should raise_error(ArgumentError)
+    -> { File.split }.should.raise(ArgumentError)
+    -> { File.split('string', 'another string') }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError if the argument is not a String type" do
-    -> { File.split(1) }.should raise_error(TypeError)
+    -> { File.split(1) }.should.raise(TypeError)
   end
 
   it "coerces the argument with to_str if it is not a String type" do
diff --git a/spec/ruby/core/file/stat/atime_spec.rb b/spec/ruby/core/file/stat/atime_spec.rb
index 9f1111ced1..2fecaed300 100644
--- a/spec/ruby/core/file/stat/atime_spec.rb
+++ b/spec/ruby/core/file/stat/atime_spec.rb
@@ -12,7 +12,7 @@ describe "File::Stat#atime" do
 
   it "returns the atime of a File::Stat object" do
     st = File.stat(@file)
-    st.atime.should be_kind_of(Time)
+    st.atime.should.is_a?(Time)
     st.atime.should <= Time.now
   end
 end
diff --git a/spec/ruby/core/file/stat/birthtime_spec.rb b/spec/ruby/core/file/stat/birthtime_spec.rb
index a727bbe566..728f635397 100644
--- a/spec/ruby/core/file/stat/birthtime_spec.rb
+++ b/spec/ruby/core/file/stat/birthtime_spec.rb
@@ -1,27 +1,29 @@
 require_relative '../../../spec_helper'
 
-describe "File::Stat#birthtime" do
-  before :each do
-    @file = tmp('i_exist')
-    touch(@file) { |f| f.write "rubinius" }
-  end
+platform_is(:windows, :darwin, :freebsd, :netbsd,
+            *ruby_version_is("4.0") { :linux },
+           ) do
+  not_implemented_messages = [
+    "birthtime() function is unimplemented", # unsupported OS/version
+    "birthtime is unimplemented",            # unsupported filesystem
+  ]
 
-  after :each do
-    rm_r @file
-  end
+  describe "File::Stat#birthtime" do
+    before :each do
+      @file = tmp('i_exist')
+      touch(@file) { |f| f.write "rubinius" }
+    end
 
-  platform_is :windows, :darwin, :freebsd, :netbsd do
-    it "returns the birthtime of a File::Stat object" do
-      st = File.stat(@file)
-      st.birthtime.should be_kind_of(Time)
-      st.birthtime.should <= Time.now
+    after :each do
+      rm_r @file
     end
-  end
 
-  platform_is :linux, :openbsd do
-    it "raises an NotImplementedError" do
+    it "returns the birthtime of a File::Stat object" do
       st = File.stat(@file)
-      -> { st.birthtime }.should raise_error(NotImplementedError)
+      st.birthtime.should.is_a?(Time)
+      st.birthtime.should <= Time.now
+    rescue NotImplementedError => e
+      e.message.should.start_with?(*not_implemented_messages)
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/blocks_spec.rb b/spec/ruby/core/file/stat/blocks_spec.rb
index f3f903d0f7..5e0efc8bc2 100644
--- a/spec/ruby/core/file/stat/blocks_spec.rb
+++ b/spec/ruby/core/file/stat/blocks_spec.rb
@@ -21,7 +21,7 @@ describe "File::Stat#blocks" do
   platform_is :windows do
     it "returns nil" do
       st = File.stat(@file)
-      st.blocks.should be_nil
+      st.blocks.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/ctime_spec.rb b/spec/ruby/core/file/stat/ctime_spec.rb
index fd50487a0a..dbf43a7453 100644
--- a/spec/ruby/core/file/stat/ctime_spec.rb
+++ b/spec/ruby/core/file/stat/ctime_spec.rb
@@ -12,7 +12,7 @@ describe "File::Stat#ctime" do
 
   it "returns the ctime of a File::Stat object" do
     st = File.stat(@file)
-    st.ctime.should be_kind_of(Time)
+    st.ctime.should.is_a?(Time)
     st.ctime.should <= Time.now
   end
 end
diff --git a/spec/ruby/core/file/stat/dev_major_spec.rb b/spec/ruby/core/file/stat/dev_major_spec.rb
index 4966d609e2..a199eaaa11 100644
--- a/spec/ruby/core/file/stat/dev_major_spec.rb
+++ b/spec/ruby/core/file/stat/dev_major_spec.rb
@@ -11,13 +11,13 @@ describe "File::Stat#dev_major" do
 
   platform_is_not :windows do
     it "returns the major part of File::Stat#dev" do
-      File.stat(@name).dev_major.should be_kind_of(Integer)
+      File.stat(@name).dev_major.should.is_a?(Integer)
     end
   end
 
   platform_is :windows do
     it "returns nil" do
-      File.stat(@name).dev_major.should be_nil
+      File.stat(@name).dev_major.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/dev_minor_spec.rb b/spec/ruby/core/file/stat/dev_minor_spec.rb
index ea79c12b99..8ce94778ca 100644
--- a/spec/ruby/core/file/stat/dev_minor_spec.rb
+++ b/spec/ruby/core/file/stat/dev_minor_spec.rb
@@ -11,13 +11,13 @@ describe "File::Stat#dev_minor" do
 
   platform_is_not :windows do
     it "returns the minor part of File::Stat#dev" do
-      File.stat(@name).dev_minor.should be_kind_of(Integer)
+      File.stat(@name).dev_minor.should.is_a?(Integer)
     end
   end
 
   platform_is :windows do
     it "returns nil" do
-      File.stat(@name).dev_minor.should be_nil
+      File.stat(@name).dev_minor.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/dev_spec.rb b/spec/ruby/core/file/stat/dev_spec.rb
index e953fcaa58..cd5e3d175e 100644
--- a/spec/ruby/core/file/stat/dev_spec.rb
+++ b/spec/ruby/core/file/stat/dev_spec.rb
@@ -10,6 +10,6 @@ describe "File::Stat#dev" do
   end
 
   it "returns the number of the device on which the file exists" do
-    File.stat(@name).dev.should be_kind_of(Integer)
+    File.stat(@name).dev.should.is_a?(Integer)
   end
 end
diff --git a/spec/ruby/core/file/stat/ftype_spec.rb b/spec/ruby/core/file/stat/ftype_spec.rb
index eb892eae5f..df2e3ada1e 100644
--- a/spec/ruby/core/file/stat/ftype_spec.rb
+++ b/spec/ruby/core/file/stat/ftype_spec.rb
@@ -8,7 +8,7 @@ describe "File::Stat#ftype" do
 
   it "returns a String" do
     FileSpecs.normal_file do |file|
-      File.lstat(file).ftype.should be_kind_of(String)
+      File.lstat(file).ftype.should.is_a?(String)
     end
   end
 
diff --git a/spec/ruby/core/file/stat/ino_spec.rb b/spec/ruby/core/file/stat/ino_spec.rb
index 42370aecb7..c09b6448c7 100644
--- a/spec/ruby/core/file/stat/ino_spec.rb
+++ b/spec/ruby/core/file/stat/ino_spec.rb
@@ -13,7 +13,7 @@ describe "File::Stat#ino" do
   platform_is_not :windows do
     it "returns the ino of a File::Stat object" do
       st = File.stat(@file)
-      st.ino.should be_kind_of(Integer)
+      st.ino.should.is_a?(Integer)
       st.ino.should > 0
     end
   end
@@ -21,7 +21,7 @@ describe "File::Stat#ino" do
   platform_is :windows do
     it "returns BY_HANDLE_FILE_INFORMATION.nFileIndexHigh/Low of a File::Stat object" do
       st = File.stat(@file)
-      st.ino.should be_kind_of(Integer)
+      st.ino.should.is_a?(Integer)
       st.ino.should > 0
     end
   end
diff --git a/spec/ruby/core/file/stat/mtime_spec.rb b/spec/ruby/core/file/stat/mtime_spec.rb
index 08a2b83463..7844491212 100644
--- a/spec/ruby/core/file/stat/mtime_spec.rb
+++ b/spec/ruby/core/file/stat/mtime_spec.rb
@@ -12,7 +12,7 @@ describe "File::Stat#mtime" do
 
   it "returns the mtime of a File::Stat object" do
     st = File.stat(@file)
-    st.mtime.should be_kind_of(Time)
+    st.mtime.should.is_a?(Time)
     st.mtime.should <= Time.now
   end
 end
diff --git a/spec/ruby/core/file/stat/new_spec.rb b/spec/ruby/core/file/stat/new_spec.rb
index c0d9432ac8..b8c3600028 100644
--- a/spec/ruby/core/file/stat/new_spec.rb
+++ b/spec/ruby/core/file/stat/new_spec.rb
@@ -15,12 +15,12 @@ describe "File::Stat#initialize" do
   it "raises an exception if the file doesn't exist" do
     -> {
       File::Stat.new(tmp("i_am_a_dummy_file_that_doesnt_exist"))
-    }.should raise_error(Errno::ENOENT)
+    }.should.raise(Errno::ENOENT)
   end
 
   it "creates a File::Stat object for the given file" do
     st = File::Stat.new(@file)
-    st.should be_kind_of(File::Stat)
+    st.should.is_a?(File::Stat)
     st.ftype.should == 'file'
   end
 
diff --git a/spec/ruby/core/file/stat/nlink_spec.rb b/spec/ruby/core/file/stat/nlink_spec.rb
index 2dd0bff124..7143923cfc 100644
--- a/spec/ruby/core/file/stat/nlink_spec.rb
+++ b/spec/ruby/core/file/stat/nlink_spec.rb
@@ -11,7 +11,7 @@ describe "File::Stat#nlink" do
     rm_r @link, @file
   end
 
-  platform_is_not :windows do
+  platform_is_not :windows, :android do
     it "returns the number of links to a file" do
       File::Stat.new(@file).nlink.should == 1
       File.link(@file, @link)
diff --git a/spec/ruby/core/file/stat/owned_spec.rb b/spec/ruby/core/file/stat/owned_spec.rb
index 6f0c250f88..a23ad850c5 100644
--- a/spec/ruby/core/file/stat/owned_spec.rb
+++ b/spec/ruby/core/file/stat/owned_spec.rb
@@ -18,15 +18,15 @@ describe "File::Stat#owned?" do
 
   it "returns true if the file is owned by the user" do
     st = File.stat(@file)
-    st.owned?.should == true
+    st.should.owned?
   end
 
-  platform_is_not :windows do
+  platform_is_not :windows, :android do
     as_user do
       it "returns false if the file is not owned by the user" do
         system_file = '/etc/passwd'
         st = File.stat(system_file)
-        st.owned?.should == false
+        st.should_not.owned?
       end
     end
   end
diff --git a/spec/ruby/core/file/stat/pipe_spec.rb b/spec/ruby/core/file/stat/pipe_spec.rb
index 7abb6c742a..692dfbf42a 100644
--- a/spec/ruby/core/file/stat/pipe_spec.rb
+++ b/spec/ruby/core/file/stat/pipe_spec.rb
@@ -12,7 +12,7 @@ describe "File::Stat#pipe?" do
     touch(filename)
 
     st = File.stat(filename)
-    st.pipe?.should == false
+    st.should_not.pipe?
 
     rm_r filename
   end
@@ -23,7 +23,7 @@ describe "File::Stat#pipe?" do
       File.mkfifo(filename)
 
       st = File.stat(filename)
-      st.pipe?.should == true
+      st.should.pipe?
 
       rm_r filename
     end
diff --git a/spec/ruby/core/file/stat/rdev_major_spec.rb b/spec/ruby/core/file/stat/rdev_major_spec.rb
index f8a8d1b107..e1b44fc2d0 100644
--- a/spec/ruby/core/file/stat/rdev_major_spec.rb
+++ b/spec/ruby/core/file/stat/rdev_major_spec.rb
@@ -2,30 +2,23 @@ require_relative '../../../spec_helper'
 
 describe "File::Stat#rdev_major" do
   before :each do
-    platform_is :solaris do
-      @name = "/dev/zfs"
-    end
-    platform_is_not :solaris do
-      @name = tmp("file.txt")
-      touch(@name)
-    end
+    @name = tmp("file.txt")
+    touch(@name)
   end
 
   after :each do
-    platform_is_not :solaris do
-      rm_r @name
-    end
+    rm_r @name
   end
 
   platform_is_not :windows do
     it "returns the major part of File::Stat#rdev" do
-      File.stat(@name).rdev_major.should be_kind_of(Integer)
+      File.stat(@name).rdev_major.should.is_a?(Integer)
     end
   end
 
   platform_is :windows do
     it "returns nil" do
-      File.stat(@name).rdev_major.should be_nil
+      File.stat(@name).rdev_major.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/rdev_minor_spec.rb b/spec/ruby/core/file/stat/rdev_minor_spec.rb
index dc30c1f56c..8af3b9f587 100644
--- a/spec/ruby/core/file/stat/rdev_minor_spec.rb
+++ b/spec/ruby/core/file/stat/rdev_minor_spec.rb
@@ -2,30 +2,23 @@ require_relative '../../../spec_helper'
 
 describe "File::Stat#rdev_minor" do
   before :each do
-    platform_is :solaris do
-      @name = "/dev/zfs"
-    end
-    platform_is_not :solaris do
-      @name = tmp("file.txt")
-      touch(@name)
-    end
+    @name = tmp("file.txt")
+    touch(@name)
   end
 
   after :each do
-    platform_is_not :solaris do
-      rm_r @name
-    end
+    rm_r @name
   end
 
   platform_is_not :windows do
     it "returns the minor part of File::Stat#rdev" do
-      File.stat(@name).rdev_minor.should be_kind_of(Integer)
+      File.stat(@name).rdev_minor.should.is_a?(Integer)
     end
   end
 
   platform_is :windows do
     it "returns nil" do
-      File.stat(@name).rdev_minor.should be_nil
+      File.stat(@name).rdev_minor.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/file/stat/rdev_spec.rb b/spec/ruby/core/file/stat/rdev_spec.rb
index 9e1aee692d..7e4252fcc6 100644
--- a/spec/ruby/core/file/stat/rdev_spec.rb
+++ b/spec/ruby/core/file/stat/rdev_spec.rb
@@ -10,6 +10,6 @@ describe "File::Stat#rdev" do
   end
 
   it "returns the number of the device this file represents which the file exists" do
-    File.stat(@name).rdev.should be_kind_of(Integer)
+    File.stat(@name).rdev.should.is_a?(Integer)
   end
 end
diff --git a/spec/ruby/core/file/stat_spec.rb b/spec/ruby/core/file/stat_spec.rb
index 31f9dc58af..d5238b6331 100644
--- a/spec/ruby/core/file/stat_spec.rb
+++ b/spec/ruby/core/file/stat_spec.rb
@@ -23,14 +23,14 @@ platform_is_not :windows do
 
         st = f.stat
 
-        st.file?.should == true
-        st.zero?.should == false
+        st.should.file?
+        st.should_not.zero?
         st.size.should == 8
         st.size?.should == 8
         st.blksize.should >= 0
-        st.atime.should be_kind_of(Time)
-        st.ctime.should be_kind_of(Time)
-        st.mtime.should be_kind_of(Time)
+        st.atime.should.is_a?(Time)
+        st.ctime.should.is_a?(Time)
+        st.mtime.should.is_a?(Time)
       end
     end
 
@@ -38,8 +38,18 @@ platform_is_not :windows do
       File.symlink(@file, @link)
       st = File.stat(@link)
 
-      st.file?.should == true
-      st.symlink?.should == false
+      st.should.file?
+      st.should_not.symlink?
+    end
+
+    it "returns an error when given missing non-ASCII path" do
+      missing_path = "/missingfilepath\xE3E4".b
+      -> {
+        File.stat(missing_path)
+      }.should.raise(SystemCallError) { |e|
+        [Errno::ENOENT, Errno::EILSEQ].should.include?(e.class)
+        e.message.should.include?(missing_path)
+      }
     end
   end
 end
diff --git a/spec/ruby/core/file/symlink_spec.rb b/spec/ruby/core/file/symlink_spec.rb
index 0e8b0a5a20..4ceeb28c84 100644
--- a/spec/ruby/core/file/symlink_spec.rb
+++ b/spec/ruby/core/file/symlink_spec.rb
@@ -32,18 +32,18 @@ describe "File.symlink" do
 
     it "raises an Errno::EEXIST if the target already exists" do
       File.symlink(@file, @link)
-      -> { File.symlink(@file, @link) }.should raise_error(Errno::EEXIST)
+      -> { File.symlink(@file, @link) }.should.raise(Errno::EEXIST)
     end
 
     it "raises an ArgumentError if not called with two arguments" do
-      -> { File.symlink        }.should raise_error(ArgumentError)
-      -> { File.symlink(@file) }.should raise_error(ArgumentError)
+      -> { File.symlink        }.should.raise(ArgumentError)
+      -> { File.symlink(@file) }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if not called with String types" do
-      -> { File.symlink(@file, nil) }.should raise_error(TypeError)
-      -> { File.symlink(@file, 1)   }.should raise_error(TypeError)
-      -> { File.symlink(1, 1)       }.should raise_error(TypeError)
+      -> { File.symlink(@file, nil) }.should.raise(TypeError)
+      -> { File.symlink(@file, 1)   }.should.raise(TypeError)
+      -> { File.symlink(1, 1)       }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/file/truncate_spec.rb b/spec/ruby/core/file/truncate_spec.rb
index 43b86b7382..5f37f34155 100644
--- a/spec/ruby/core/file/truncate_spec.rb
+++ b/spec/ruby/core/file/truncate_spec.rb
@@ -18,7 +18,7 @@ describe "File.truncate" do
 
     File.open(@name, "r") do |f|
       f.read(99).should == "12345"
-      f.eof?.should == true
+      f.should.eof?
     end
   end
 
@@ -54,29 +54,29 @@ describe "File.truncate" do
     rm_r not_existing_file
 
     begin
-      -> { File.truncate(not_existing_file, 5) }.should raise_error(Errno::ENOENT)
+      -> { File.truncate(not_existing_file, 5) }.should.raise(Errno::ENOENT)
     ensure
       rm_r not_existing_file
     end
   end
 
   it "raises an ArgumentError if not passed two arguments" do
-    -> { File.truncate        }.should raise_error(ArgumentError)
-    -> { File.truncate(@name) }.should raise_error(ArgumentError)
+    -> { File.truncate        }.should.raise(ArgumentError)
+    -> { File.truncate(@name) }.should.raise(ArgumentError)
   end
 
   platform_is_not :netbsd, :openbsd do
     it "raises an Errno::EINVAL if the length argument is not valid" do
-      -> { File.truncate(@name, -1)  }.should raise_error(Errno::EINVAL) # May fail
+      -> { File.truncate(@name, -1)  }.should.raise(Errno::EINVAL) # May fail
     end
   end
 
   it "raises a TypeError if not passed a String type for the first argument" do
-    -> { File.truncate(1, 1) }.should raise_error(TypeError)
+    -> { File.truncate(1, 1) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if not passed an Integer type for the second argument" do
-    -> { File.truncate(@name, nil) }.should raise_error(TypeError)
+    -> { File.truncate(@name, nil) }.should.raise(TypeError)
   end
 
   it "accepts an object that has a #to_path method" do
@@ -120,7 +120,7 @@ describe "File#truncate" do
     File.size(@name).should == 5
     File.open(@name, "r") do |f|
       f.read(99).should == "12345"
-      f.eof?.should == true
+      f.should.eof?
     end
   end
 
@@ -149,29 +149,29 @@ describe "File#truncate" do
   end
 
   it "raises an ArgumentError if not passed one argument" do
-    -> { @file.truncate        }.should raise_error(ArgumentError)
-    -> { @file.truncate(1) }.should_not raise_error(ArgumentError)
+    -> { @file.truncate        }.should.raise(ArgumentError)
+    -> { @file.truncate(1) }.should_not.raise(ArgumentError)
   end
 
   platform_is_not :netbsd do
     it "raises an Errno::EINVAL if the length argument is not valid" do
-      -> { @file.truncate(-1)  }.should raise_error(Errno::EINVAL) # May fail
+      -> { @file.truncate(-1)  }.should.raise(Errno::EINVAL) # May fail
     end
   end
 
   it "raises an IOError if file is closed" do
     @file.close
-    @file.closed?.should == true
-    -> { @file.truncate(42) }.should raise_error(IOError)
+    @file.should.closed?
+    -> { @file.truncate(42) }.should.raise(IOError)
   end
 
   it "raises an IOError if file is not opened for writing" do
     File.open(@name, 'r') do |file|
-      -> { file.truncate(42) }.should raise_error(IOError)
+      -> { file.truncate(42) }.should.raise(IOError)
     end
   end
 
   it "raises a TypeError if not passed an Integer type for the for the argument" do
-    -> { @file.truncate(nil) }.should raise_error(TypeError)
+    -> { @file.truncate(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/file/umask_spec.rb b/spec/ruby/core/file/umask_spec.rb
index 2640e3c316..fea8cf7633 100644
--- a/spec/ruby/core/file/umask_spec.rb
+++ b/spec/ruby/core/file/umask_spec.rb
@@ -12,8 +12,8 @@ describe "File.umask" do
     File.umask(@orig_umask)
   end
 
-  it "returns a Fixnum" do
-    File.umask.should be_kind_of(Fixnum)
+  it "returns an Integer" do
+    File.umask.should.is_a?(Integer)
   end
 
   platform_is_not :windows do
@@ -47,11 +47,11 @@ describe "File.umask" do
   end
 
   it "raises RangeError with too large values" do
-    -> { File.umask(2**64) }.should raise_error(RangeError)
-    -> { File.umask(-2**63 - 1) }.should raise_error(RangeError)
+    -> { File.umask(2**64) }.should.raise(RangeError)
+    -> { File.umask(-2**63 - 1) }.should.raise(RangeError)
   end
 
   it "raises ArgumentError when more than one argument is provided" do
-    -> { File.umask(022, 022) }.should raise_error(ArgumentError)
+    -> { File.umask(022, 022) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/file/utime_spec.rb b/spec/ruby/core/file/utime_spec.rb
index 03adc76efe..d87626be50 100644
--- a/spec/ruby/core/file/utime_spec.rb
+++ b/spec/ruby/core/file/utime_spec.rb
@@ -1,83 +1,6 @@
 require_relative '../../spec_helper'
+require_relative 'shared/update_time'
 
 describe "File.utime" do
-
-  before :all do
-    @time_is_float = /mswin|mingw/ =~ RUBY_PLATFORM && RUBY_VERSION >= '2.5'
-  end
-
-  before :each do
-    @atime = Time.now
-    @mtime = Time.now
-    @file1 = tmp("specs_file_utime1")
-    @file2 = tmp("specs_file_utime2")
-    touch @file1
-    touch @file2
-  end
-
-  after :each do
-    rm_r @file1, @file2
-  end
-
-  it "sets the access and modification time of each file" do
-    File.utime(@atime, @mtime, @file1, @file2)
-    if @time_is_float
-      File.atime(@file1).should be_close(@atime, 0.0001)
-      File.mtime(@file1).should be_close(@mtime, 0.0001)
-      File.atime(@file2).should be_close(@atime, 0.0001)
-      File.mtime(@file2).should be_close(@mtime, 0.0001)
-    else
-      File.atime(@file1).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
-      File.mtime(@file1).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
-      File.atime(@file2).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
-      File.mtime(@file2).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
-    end
-  end
-
-  it "uses the current times if two nil values are passed" do
-    tn = Time.now
-    File.utime(nil, nil, @file1, @file2)
-    if @time_is_float
-      File.atime(@file1).should be_close(tn, 0.050)
-      File.mtime(@file1).should be_close(tn, 0.050)
-      File.atime(@file2).should be_close(tn, 0.050)
-      File.mtime(@file2).should be_close(tn, 0.050)
-    else
-      File.atime(@file1).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
-      File.mtime(@file1).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
-      File.atime(@file2).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
-      File.mtime(@file2).to_i.should be_close(Time.now.to_i, TIME_TOLERANCE)
-    end
-  end
-
-  it "accepts an object that has a #to_path method" do
-    File.utime(@atime, @mtime, mock_to_path(@file1), mock_to_path(@file2))
-  end
-
-  it "accepts numeric atime and mtime arguments" do
-    if @time_is_float
-      File.utime(@atime.to_f, @mtime.to_f, @file1, @file2)
-      File.atime(@file1).should be_close(@atime, 0.0001)
-      File.mtime(@file1).should be_close(@mtime, 0.0001)
-      File.atime(@file2).should be_close(@atime, 0.0001)
-      File.mtime(@file2).should be_close(@mtime, 0.0001)
-    else
-      File.utime(@atime.to_i, @mtime.to_i, @file1, @file2)
-      File.atime(@file1).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
-      File.mtime(@file1).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
-      File.atime(@file2).to_i.should be_close(@atime.to_i, TIME_TOLERANCE)
-      File.mtime(@file2).to_i.should be_close(@mtime.to_i, TIME_TOLERANCE)
-    end
-  end
-
-  platform_is :linux do
-    platform_is wordsize: 64 do
-      it "allows Time instances in the far future to set mtime and atime" do
-        time = Time.at(1<<44)
-        File.utime(time, time, @file1)
-        File.atime(@file1).year.should == 559444
-        File.mtime(@file1).year.should == 559444
-      end
-    end
-  end
+  it_behaves_like :update_time, :utime
 end
diff --git a/spec/ruby/core/file/world_readable_spec.rb b/spec/ruby/core/file/world_readable_spec.rb
index 11b8e67d0b..0f5e0b13d7 100644
--- a/spec/ruby/core/file/world_readable_spec.rb
+++ b/spec/ruby/core/file/world_readable_spec.rb
@@ -7,6 +7,6 @@ describe "File.world_readable?" do
   it "returns nil if the file does not exist" do
     file = rand.to_s + $$.to_s
     File.should_not.exist?(file)
-    File.world_readable?(file).should be_nil
+    File.world_readable?(file).should == nil
   end
 end
diff --git a/spec/ruby/core/file/world_writable_spec.rb b/spec/ruby/core/file/world_writable_spec.rb
index d378cf2eb9..46ba6832f9 100644
--- a/spec/ruby/core/file/world_writable_spec.rb
+++ b/spec/ruby/core/file/world_writable_spec.rb
@@ -7,6 +7,6 @@ describe "File.world_writable?" do
   it "returns nil if the file does not exist" do
     file = rand.to_s + $$.to_s
     File.should_not.exist?(file)
-    File.world_writable?(file).should be_nil
+    File.world_writable?(file).should == nil
   end
 end
diff --git a/spec/ruby/core/file/zero_spec.rb b/spec/ruby/core/file/zero_spec.rb
index 63dd85ee46..01c7505ef2 100644
--- a/spec/ruby/core/file/zero_spec.rb
+++ b/spec/ruby/core/file/zero_spec.rb
@@ -4,10 +4,4 @@ require_relative '../../shared/file/zero'
 describe "File.zero?" do
   it_behaves_like :file_zero, :zero?, File
   it_behaves_like :file_zero_missing, :zero?, File
-
-  platform_is :solaris do
-    it "returns false for /dev/null" do
-      File.zero?('/dev/null').should == true
-    end
-  end
 end
diff --git a/spec/ruby/core/filetest/exist_spec.rb b/spec/ruby/core/filetest/exist_spec.rb
index 4d14bea231..612ffa9fcb 100644
--- a/spec/ruby/core/filetest/exist_spec.rb
+++ b/spec/ruby/core/filetest/exist_spec.rb
@@ -4,3 +4,9 @@ require_relative '../../shared/file/exist'
 describe "FileTest.exist?" do
   it_behaves_like :file_exist, :exist?, FileTest
 end
+
+describe "FileTest.exists?" do
+  it "has been removed" do
+    FileTest.should_not.respond_to?(:exists?)
+  end
+end
diff --git a/spec/ruby/core/filetest/exists_spec.rb b/spec/ruby/core/filetest/exists_spec.rb
deleted file mode 100644
index d090d7d740..0000000000
--- a/spec/ruby/core/filetest/exists_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../spec_helper'
-require_relative '../../shared/file/exist'
-
-describe "FileTest.exists?" do
-  it_behaves_like :file_exist, :exists?, FileTest
-end
diff --git a/spec/ruby/core/filetest/grpowned_spec.rb b/spec/ruby/core/filetest/grpowned_spec.rb
index d073cb9770..d6bd6abd71 100644
--- a/spec/ruby/core/filetest/grpowned_spec.rb
+++ b/spec/ruby/core/filetest/grpowned_spec.rb
@@ -5,6 +5,6 @@ describe "FileTest.grpowned?" do
   it_behaves_like :file_grpowned, :grpowned?, FileTest
 
   it "returns false if the file doesn't exist" do
-    FileTest.grpowned?("xxx-tmp-doesnt_exist-blah").should be_false
+    FileTest.grpowned?("xxx-tmp-doesnt_exist-blah").should == false
   end
 end
diff --git a/spec/ruby/core/filetest/socket_spec.rb b/spec/ruby/core/filetest/socket_spec.rb
index 63a6a31ecb..f274be6318 100644
--- a/spec/ruby/core/filetest/socket_spec.rb
+++ b/spec/ruby/core/filetest/socket_spec.rb
@@ -3,4 +3,8 @@ require_relative '../../shared/file/socket'
 
 describe "FileTest.socket?" do
   it_behaves_like :file_socket, :socket?, FileTest
+
+  it "returns false if file does not exist" do
+    FileTest.socket?("I_am_a_bogus_file").should == false
+  end
 end
diff --git a/spec/ruby/core/filetest/zero_spec.rb b/spec/ruby/core/filetest/zero_spec.rb
index dd6a164ec9..92cab67f1b 100644
--- a/spec/ruby/core/filetest/zero_spec.rb
+++ b/spec/ruby/core/filetest/zero_spec.rb
@@ -4,10 +4,4 @@ require_relative '../../shared/file/zero'
 describe "FileTest.zero?" do
   it_behaves_like :file_zero, :zero?, FileTest
   it_behaves_like :file_zero_missing, :zero?, FileTest
-
-  platform_is :solaris do
-    it "returns false for /dev/null" do
-      File.zero?('/dev/null').should == true
-    end
-  end
 end
diff --git a/spec/ruby/core/float/ceil_spec.rb b/spec/ruby/core/float/ceil_spec.rb
index 7fc18d304c..efd1e6feb2 100644
--- a/spec/ruby/core/float/ceil_spec.rb
+++ b/spec/ruby/core/float/ceil_spec.rb
@@ -1,21 +1,28 @@
 require_relative '../../spec_helper'
+require_relative '../integer/shared/integer_ceil_precision'
 
 describe "Float#ceil" do
+  context "with values equal to integers" do
+    it_behaves_like :integer_ceil_precision, :Float
+  end
+
   it "returns the smallest Integer greater than or equal to self" do
-    -1.2.ceil.should eql( -1)
-    -1.0.ceil.should eql( -1)
-    0.0.ceil.should  eql( 0 )
-    1.3.ceil.should  eql( 2 )
-    3.0.ceil.should  eql( 3 )
-    -9223372036854775808.1.ceil.should eql(-9223372036854775808)
-    +9223372036854775808.1.ceil.should eql(+9223372036854775808)
+    -1.2.ceil.should.eql?( -1)
+    -1.0.ceil.should.eql?( -1)
+    0.0.ceil.should.eql?( 0 )
+    1.3.ceil.should.eql?( 2 )
+    3.0.ceil.should.eql?( 3 )
+    -9223372036854775808.1.ceil.should.eql?(-9223372036854775808)
+    +9223372036854775808.1.ceil.should.eql?(+9223372036854775808)
   end
 
   it "returns the smallest number greater than or equal to self with an optionally given precision" do
-    2.1679.ceil(0).should   eql(3)
-    214.94.ceil(-1).should  eql(220)
-    7.0.ceil(1).should      eql(7.0)
-    -1.234.ceil(2).should   eql(-1.23)
-    5.123812.ceil(4).should eql(5.1239)
+    2.1679.ceil(0).should.eql?(3)
+    214.94.ceil(-1).should.eql?(220)
+    7.0.ceil(1).should.eql?(7.0)
+    200.0.ceil(-2).should.eql?(200)
+    -1.234.ceil(2).should.eql?(-1.23)
+    5.123812.ceil(4).should.eql?(5.1239)
+    10.00001.ceil(5).should.eql?(10.00001)
   end
 end
diff --git a/spec/ruby/core/float/coerce_spec.rb b/spec/ruby/core/float/coerce_spec.rb
index ea108f3303..baa831dcf6 100644
--- a/spec/ruby/core/float/coerce_spec.rb
+++ b/spec/ruby/core/float/coerce_spec.rb
@@ -9,10 +9,10 @@ describe "Float#coerce" do
     1.0.coerce(3.14).should == [3.14, 1.0]
 
     a, b = -0.0.coerce(bignum_value)
-    a.should be_close(9223372036854775808.0, TOLERANCE)
+    a.should be_close(18446744073709551616.0, TOLERANCE)
     b.should be_close(-0.0, TOLERANCE)
     a, b = 1.0.coerce(bignum_value)
-    a.should be_close(9223372036854775808.0, TOLERANCE)
+    a.should be_close(18446744073709551616.0, TOLERANCE)
     b.should be_close(1.0, TOLERANCE)
   end
 end
diff --git a/spec/ruby/core/float/comparison_spec.rb b/spec/ruby/core/float/comparison_spec.rb
index 4205d95c83..e9adf2fd6a 100644
--- a/spec/ruby/core/float/comparison_spec.rb
+++ b/spec/ruby/core/float/comparison_spec.rb
@@ -7,30 +7,107 @@ describe "Float#<=>" do
     ((bignum_value*1.1) <=> bignum_value).should == 1
   end
 
-  it "returns nil when either argument is NaN" do
-    (nan_value <=> 71.2).should be_nil
-    (1771.176 <=> nan_value).should be_nil
+  it "returns nil if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value <=> n).should == nil
+      (n <=> nan_value).should == nil
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value <=> n).should == 1
+      (n <=> infinity_value).should == -1
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (-infinity_value <=> n).should == -1
+      (n <=> -infinity_value).should == 1
+    }
   end
 
   it "returns nil when the given argument is not a Float" do
-    (1.0 <=> "1").should be_nil
+    (1.0 <=> "1").should == nil
+    (1.0 <=> "1".freeze).should == nil
+    (1.0 <=> :one).should == nil
+    (1.0 <=> true).should == nil
   end
 
-  # The 4 tests below are taken from matz's revision 23730 for Ruby trunk
-  #
-  it "returns 1 when self is Infinity and other is a Bignum" do
-    (infinity_value <=> Float::MAX.to_i*2).should == 1
+  it "compares using #coerce when argument is not a Float" do
+    klass = Class.new do
+      attr_reader :call_count
+      def coerce(other)
+        @call_count ||= 0
+        @call_count += 1
+        [other, 42.0]
+      end
+    end
+
+    coercible = klass.new
+    (2.33 <=> coercible).should == -1
+    (42.0 <=> coercible).should == 0
+    (43.0 <=> coercible).should == 1
+    coercible.call_count.should == 3
   end
 
-  it "returns -1 when self is negative and other is Infinity" do
-    (-Float::MAX.to_i*2 <=> infinity_value).should == -1
+  it "raises TypeError when #coerce misbehaves" do
+    klass = Class.new do
+      def coerce(other)
+        :incorrect
+      end
+    end
+
+    bad_coercible = klass.new
+    -> {
+      4.2 <=> bad_coercible
+    }.should.raise(TypeError, "coerce must return [x, y]")
   end
 
-  it "returns -1 when self is -Infinity and other is negative" do
+  it "returns the correct result when one side is infinite" do
+    (infinity_value <=> Float::MAX.to_i*2).should == 1
+    (-Float::MAX.to_i*2 <=> infinity_value).should == -1
     (-infinity_value <=> -Float::MAX.to_i*2).should == -1
+    (-Float::MAX.to_i*2 <=> -infinity_value).should == 1
   end
 
-  it "returns 1 when self is negative and other is -Infinity" do
-    (-Float::MAX.to_i*2 <=> -infinity_value).should == 1
+  it "returns 0 when self is Infinity and other is infinite?=1" do
+    obj = Object.new
+    def obj.infinite?
+      1
+    end
+    (infinity_value <=> obj).should == 0
+  end
+
+  it "returns 1 when self is Infinity and other is infinite?=-1" do
+    obj = Object.new
+    def obj.infinite?
+      -1
+    end
+    (infinity_value <=> obj).should == 1
+  end
+
+  it "returns 1 when self is Infinity and other is infinite?=nil (which means finite)" do
+    obj = Object.new
+    def obj.infinite?
+      nil
+    end
+    (infinity_value <=> obj).should == 1
+  end
+
+  it "returns 0 for -0.0 and 0.0" do
+    (-0.0 <=> 0.0).should == 0
+    (0.0 <=> -0.0).should == 0
+  end
+
+  it "returns 0 for -0.0 and 0" do
+    (-0.0 <=> 0).should == 0
+    (0 <=> -0.0).should == 0
+  end
+
+  it "returns 0 for 0.0 and 0" do
+    (0.0 <=> 0).should == 0
+    (0 <=> 0.0).should == 0
   end
 end
diff --git a/spec/ruby/core/float/constants_spec.rb b/spec/ruby/core/float/constants_spec.rb
index 497e0ae188..1b71ee8adf 100644
--- a/spec/ruby/core/float/constants_spec.rb
+++ b/spec/ruby/core/float/constants_spec.rb
@@ -50,6 +50,6 @@ describe "Float constant" do
   end
 
   it "NAN is 'not a number'" do
-    Float::NAN.nan?.should be_true
+    Float::NAN.nan?.should == true
   end
 end
diff --git a/spec/ruby/core/float/denominator_spec.rb b/spec/ruby/core/float/denominator_spec.rb
index 6f4fcfcf23..85beaa98cd 100644
--- a/spec/ruby/core/float/denominator_spec.rb
+++ b/spec/ruby/core/float/denominator_spec.rb
@@ -12,7 +12,7 @@ describe "Float#denominator" do
 
   it "returns an Integer" do
     @numbers.each do |number|
-      number.denominator.should be_kind_of(Integer)
+      number.denominator.should.is_a?(Integer)
     end
   end
 
diff --git a/spec/ruby/core/float/divide_spec.rb b/spec/ruby/core/float/divide_spec.rb
index d8f71a6b98..68a2c550a7 100644
--- a/spec/ruby/core/float/divide_spec.rb
+++ b/spec/ruby/core/float/divide_spec.rb
@@ -16,24 +16,28 @@ describe "Float#/" do
   end
 
   it "returns +Infinity when dividing non-zero by zero of the same sign" do
-    (1.0 / 0.0).should be_positive_infinity
-    (-1.0 / -0.0).should be_positive_infinity
+    (1.0 / 0.0).should.infinite? == 1
+    (-1.0 / -0.0).should.infinite? == 1
   end
 
   it "returns -Infinity when dividing non-zero by zero of opposite sign" do
-    (-1.0 / 0.0).should be_negative_infinity
-    (1.0 / -0.0).should be_negative_infinity
+    (-1.0 / 0.0).should.infinite? == -1
+    (1.0 / -0.0).should.infinite? == -1
   end
 
   it "returns NaN when dividing zero by zero" do
-    (0.0 / 0.0).should be_nan
-    (-0.0 / 0.0).should be_nan
-    (0.0 / -0.0).should be_nan
-    (-0.0 / -0.0).should be_nan
+    (0.0 / 0.0).should.nan?
+    (-0.0 / 0.0).should.nan?
+    (0.0 / -0.0).should.nan?
+    (-0.0 / -0.0).should.nan?
   end
 
   it "raises a TypeError when given a non-Numeric" do
-    -> { 13.0 / "10"    }.should raise_error(TypeError)
-    -> { 13.0 / :symbol }.should raise_error(TypeError)
+    -> { 13.0 / "10"    }.should.raise(TypeError)
+    -> { 13.0 / :symbol }.should.raise(TypeError)
+  end
+
+  it "divides correctly by Rational numbers" do
+    (1.2345678901234567 / Rational(1, 10000000000000000000)).should == 1.2345678901234567e+19
   end
 end
diff --git a/spec/ruby/core/float/divmod_spec.rb b/spec/ruby/core/float/divmod_spec.rb
index ec55dd3681..7ed6cd3487 100644
--- a/spec/ruby/core/float/divmod_spec.rb
+++ b/spec/ruby/core/float/divmod_spec.rb
@@ -3,41 +3,41 @@ require_relative '../../spec_helper'
 describe "Float#divmod" do
   it "returns an [quotient, modulus] from dividing self by other" do
     values = 3.14.divmod(2)
-    values[0].should eql(1)
+    values[0].should.eql?(1)
     values[1].should be_close(1.14, TOLERANCE)
     values = 2.8284.divmod(3.1415)
-    values[0].should eql(0)
+    values[0].should.eql?(0)
     values[1].should be_close(2.8284, TOLERANCE)
     values = -1.0.divmod(bignum_value)
-    values[0].should eql(-1)
-    values[1].should be_close(9223372036854775808.000, TOLERANCE)
+    values[0].should.eql?(-1)
+    values[1].should be_close(18446744073709551616.0, TOLERANCE)
     values = -1.0.divmod(1)
-    values[0].should eql(-1)
-    values[1].should eql(0.0)
+    values[0].should.eql?(-1)
+    values[1].should.eql?(0.0)
   end
 
   # Behaviour established as correct in r23953
   it "raises a FloatDomainError if self is NaN" do
-    -> { nan_value.divmod(1) }.should raise_error(FloatDomainError)
+    -> { nan_value.divmod(1) }.should.raise(FloatDomainError)
   end
 
   # Behaviour established as correct in r23953
   it "raises a FloatDomainError if other is NaN" do
-    -> { 1.divmod(nan_value) }.should raise_error(FloatDomainError)
+    -> { 1.0.divmod(nan_value) }.should.raise(FloatDomainError)
   end
 
   # Behaviour established as correct in r23953
   it "raises a FloatDomainError if self is Infinity" do
-    -> { infinity_value.divmod(1) }.should raise_error(FloatDomainError)
+    -> { infinity_value.divmod(1) }.should.raise(FloatDomainError)
   end
 
   it "raises a ZeroDivisionError if other is zero" do
-    -> { 1.0.divmod(0)   }.should raise_error(ZeroDivisionError)
-    -> { 1.0.divmod(0.0) }.should raise_error(ZeroDivisionError)
+    -> { 1.0.divmod(0)   }.should.raise(ZeroDivisionError)
+    -> { 1.0.divmod(0.0) }.should.raise(ZeroDivisionError)
   end
 
   # redmine #5276"
   it "returns the correct [quotient, modulus] even for large quotient" do
-    0.59.divmod(7.761021455128987e-11).first.should eql(7602092113)
+    0.59.divmod(7.761021455128987e-11).first.should.eql?(7602092113)
   end
 end
diff --git a/spec/ruby/core/float/dup_spec.rb b/spec/ruby/core/float/dup_spec.rb
index 294da8e2bc..b474e21325 100644
--- a/spec/ruby/core/float/dup_spec.rb
+++ b/spec/ruby/core/float/dup_spec.rb
@@ -3,6 +3,6 @@ require_relative '../../spec_helper'
 describe "Float#dup" do
   it "returns self" do
     float = 2.4
-    float.dup.should equal(float)
+    float.dup.should.equal?(float)
   end
 end
diff --git a/spec/ruby/core/float/eql_spec.rb b/spec/ruby/core/float/eql_spec.rb
index 6b5f91db33..cf1ad8416f 100644
--- a/spec/ruby/core/float/eql_spec.rb
+++ b/spec/ruby/core/float/eql_spec.rb
@@ -2,15 +2,15 @@ require_relative '../../spec_helper'
 
 describe "Float#eql?" do
   it "returns true if other is a Float equal to self" do
-    0.0.eql?(0.0).should be_true
+    0.0.eql?(0.0).should == true
   end
 
   it "returns false if other is a Float not equal to self" do
-    1.0.eql?(1.1).should be_false
+    1.0.eql?(1.1).should == false
   end
 
   it "returns false if other is not a Float" do
-    1.0.eql?(1).should be_false
-    1.0.eql?(:one).should be_false
+    1.0.eql?(1).should == false
+    1.0.eql?(:one).should == false
   end
 end
diff --git a/spec/ruby/core/float/finite_spec.rb b/spec/ruby/core/float/finite_spec.rb
index c5fb3df849..d839b30e32 100644
--- a/spec/ruby/core/float/finite_spec.rb
+++ b/spec/ruby/core/float/finite_spec.rb
@@ -2,18 +2,18 @@ require_relative '../../spec_helper'
 
 describe "Float#finite?" do
   it "returns true for finite values" do
-    3.14159.finite?.should == true
+    3.14159.should.finite?
   end
 
   it "returns false for positive infinity" do
-    infinity_value.finite?.should == false
+    infinity_value.should_not.finite?
   end
 
   it "returns false for negative infinity" do
-    (-infinity_value).finite?.should == false
+    (-infinity_value).should_not.finite?
   end
 
   it "returns false for NaN" do
-    nan_value.finite?.should == false
+    nan_value.should_not.finite?
   end
 end
diff --git a/spec/ruby/core/float/float_spec.rb b/spec/ruby/core/float/float_spec.rb
index 263ae82079..46b2eff372 100644
--- a/spec/ruby/core/float/float_spec.rb
+++ b/spec/ruby/core/float/float_spec.rb
@@ -8,12 +8,12 @@ describe "Float" do
   it ".allocate raises a TypeError" do
     -> do
       Float.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       Float.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/float/floor_spec.rb b/spec/ruby/core/float/floor_spec.rb
index 046216d36d..f77300eb04 100644
--- a/spec/ruby/core/float/floor_spec.rb
+++ b/spec/ruby/core/float/floor_spec.rb
@@ -1,21 +1,28 @@
 require_relative '../../spec_helper'
+require_relative '../integer/shared/integer_floor_precision'
 
 describe "Float#floor" do
+  context "with values equal to integers" do
+    it_behaves_like :integer_floor_precision, :Float
+  end
+
   it "returns the largest Integer less than or equal to self" do
-    -1.2.floor.should eql( -2)
-    -1.0.floor.should eql( -1)
-    0.0.floor.should  eql( 0 )
-    1.0.floor.should  eql( 1 )
-    5.9.floor.should  eql( 5 )
-    -9223372036854775808.1.floor.should eql(-9223372036854775808)
-    +9223372036854775808.1.floor.should eql(+9223372036854775808)
+    -1.2.floor.should.eql?( -2)
+    -1.0.floor.should.eql?( -1)
+    0.0.floor.should.eql?( 0 )
+    1.0.floor.should.eql?( 1 )
+    5.9.floor.should.eql?( 5 )
+    -9223372036854775808.1.floor.should.eql?(-9223372036854775808)
+    +9223372036854775808.1.floor.should.eql?(+9223372036854775808)
   end
 
   it "returns the largest number less than or equal to self with an optionally given precision" do
-    2.1679.floor(0).should   eql(2)
-    214.94.floor(-1).should  eql(210)
-    7.0.floor(1).should      eql(7.0)
-    -1.234.floor(2).should   eql(-1.24)
-    5.123812.floor(4).should eql(5.1238)
+    2.1679.floor(0).should.eql?(2)
+    214.94.floor(-1).should.eql?(210)
+    7.0.floor(1).should.eql?(7.0)
+    200.0.floor(-2).should.eql?(200)
+    -1.234.floor(2).should.eql?(-1.24)
+    5.123812.floor(4).should.eql?(5.1238)
+    10.00001.floor(5).should.eql?(10.00001)
   end
 end
diff --git a/spec/ruby/core/float/gt_spec.rb b/spec/ruby/core/float/gt_spec.rb
index 0d73f1c3df..5194796b46 100644
--- a/spec/ruby/core/float/gt_spec.rb
+++ b/spec/ruby/core/float/gt_spec.rb
@@ -11,7 +11,28 @@ describe "Float#>" do
   end
 
   it "raises an ArgumentError when given a non-Numeric" do
-    -> { 5.0 > "4"       }.should raise_error(ArgumentError)
-    -> { 5.0 > mock('x') }.should raise_error(ArgumentError)
+    -> { 5.0 > "4"       }.should.raise(ArgumentError)
+    -> { 5.0 > mock('x') }.should.raise(ArgumentError)
+  end
+
+  it "returns false if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value > n).should == false
+      (n > nan_value).should == false
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value > n).should == true
+      (n > infinity_value).should == false
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (-infinity_value > n).should == false
+      (n > -infinity_value).should == true
+    }
   end
 end
diff --git a/spec/ruby/core/float/gte_spec.rb b/spec/ruby/core/float/gte_spec.rb
index 98ec60b70b..4a62725d53 100644
--- a/spec/ruby/core/float/gte_spec.rb
+++ b/spec/ruby/core/float/gte_spec.rb
@@ -11,7 +11,28 @@ describe "Float#>=" do
   end
 
   it "raises an ArgumentError when given a non-Numeric" do
-    -> { 5.0 >= "4"       }.should raise_error(ArgumentError)
-    -> { 5.0 >= mock('x') }.should raise_error(ArgumentError)
+    -> { 5.0 >= "4"       }.should.raise(ArgumentError)
+    -> { 5.0 >= mock('x') }.should.raise(ArgumentError)
+  end
+
+  it "returns false if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value >= n).should == false
+      (n >= nan_value).should == false
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value >= n).should == true
+      (n >= infinity_value).should == false
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (-infinity_value >= n).should == false
+      (n >= -infinity_value).should == true
+    }
   end
 end
diff --git a/spec/ruby/core/float/inspect_spec.rb b/spec/ruby/core/float/inspect_spec.rb
new file mode 100644
index 0000000000..4be1927d84
--- /dev/null
+++ b/spec/ruby/core/float/inspect_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/to_s'
+
+describe "Float#inspect" do
+  it_behaves_like :float_to_s, :inspect
+end
diff --git a/spec/ruby/core/float/lt_spec.rb b/spec/ruby/core/float/lt_spec.rb
index c01b6e0e02..0f0e1752bd 100644
--- a/spec/ruby/core/float/lt_spec.rb
+++ b/spec/ruby/core/float/lt_spec.rb
@@ -11,7 +11,28 @@ describe "Float#<" do
   end
 
   it "raises an ArgumentError when given a non-Numeric" do
-    -> { 5.0 < "4"       }.should raise_error(ArgumentError)
-    -> { 5.0 < mock('x') }.should raise_error(ArgumentError)
+    -> { 5.0 < "4"       }.should.raise(ArgumentError)
+    -> { 5.0 < mock('x') }.should.raise(ArgumentError)
+  end
+
+  it "returns false if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value < n).should == false
+      (n < nan_value).should == false
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value < n).should == false
+      (n < infinity_value).should == true
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (-infinity_value < n).should == true
+      (n < -infinity_value).should == false
+    }
   end
 end
diff --git a/spec/ruby/core/float/lte_spec.rb b/spec/ruby/core/float/lte_spec.rb
index 66f2ddc2c7..afb64ade09 100644
--- a/spec/ruby/core/float/lte_spec.rb
+++ b/spec/ruby/core/float/lte_spec.rb
@@ -12,7 +12,28 @@ describe "Float#<=" do
   end
 
   it "raises an ArgumentError when given a non-Numeric" do
-    -> { 5.0 <= "4"       }.should raise_error(ArgumentError)
-    -> { 5.0 <= mock('x') }.should raise_error(ArgumentError)
+    -> { 5.0 <= "4"       }.should.raise(ArgumentError)
+    -> { 5.0 <= mock('x') }.should.raise(ArgumentError)
+  end
+
+  it "returns false if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value <= n).should == false
+      (n <= nan_value).should == false
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value <= n).should == false
+      (n <= infinity_value).should == true
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (-infinity_value <= n).should == true
+      (n <= -infinity_value).should == false
+    }
   end
 end
diff --git a/spec/ruby/core/float/magnitude_spec.rb b/spec/ruby/core/float/magnitude_spec.rb
index db577c15c5..7cdd8ef28a 100644
--- a/spec/ruby/core/float/magnitude_spec.rb
+++ b/spec/ruby/core/float/magnitude_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../spec_helper"
 require_relative 'shared/abs'
 
 describe "Float#magnitude" do
diff --git a/spec/ruby/core/float/minus_spec.rb b/spec/ruby/core/float/minus_spec.rb
index 5626cbdac2..a4281a397b 100644
--- a/spec/ruby/core/float/minus_spec.rb
+++ b/spec/ruby/core/float/minus_spec.rb
@@ -6,7 +6,7 @@ describe "Float#-" do
 
   it "returns self minus other" do
     (9_237_212.5280 - 5_280).should be_close(9231932.528, TOLERANCE)
-    (2_560_496.1691 - bignum_value).should be_close(-9223372036852215808.000, TOLERANCE)
+    (2_560_496.1691 - bignum_value).should be_close(-18446744073706991616.0, TOLERANCE)
     (5.5 - 5.5).should be_close(0.0,TOLERANCE)
   end
 end
diff --git a/spec/ruby/core/float/multiply_spec.rb b/spec/ruby/core/float/multiply_spec.rb
index eca0b52c4f..edaaba7e61 100644
--- a/spec/ruby/core/float/multiply_spec.rb
+++ b/spec/ruby/core/float/multiply_spec.rb
@@ -7,11 +7,11 @@ describe "Float#*" do
   it "returns self multiplied by other" do
     (4923.98221 * 2).should be_close(9847.96442, TOLERANCE)
     (6712.5 * 0.25).should be_close(1678.125, TOLERANCE)
-    (256.4096 * bignum_value).should be_close(2364961134621118431232.000, TOLERANCE)
+    (256.4096 * bignum_value).should be_close(4729922269242236862464.0, TOLERANCE)
   end
 
   it "raises a TypeError when given a non-Numeric" do
-    -> { 13.0 * "10"    }.should raise_error(TypeError)
-    -> { 13.0 * :symbol }.should raise_error(TypeError)
+    -> { 13.0 * "10"    }.should.raise(TypeError)
+    -> { 13.0 * :symbol }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/float/nan_spec.rb b/spec/ruby/core/float/nan_spec.rb
index d09d25153c..c1043ef21b 100644
--- a/spec/ruby/core/float/nan_spec.rb
+++ b/spec/ruby/core/float/nan_spec.rb
@@ -2,8 +2,8 @@ require_relative '../../spec_helper'
 
 describe "Float#nan?" do
   it "returns true if self is not a valid IEEE floating-point number" do
-    0.0.nan?.should == false
-    -1.5.nan?.should == false
-    nan_value.nan?.should == true
+    0.0.should_not.nan?
+    -1.5.should_not.nan?
+    nan_value.should.nan?
   end
 end
diff --git a/spec/ruby/core/float/negative_spec.rb b/spec/ruby/core/float/negative_spec.rb
new file mode 100644
index 0000000000..484e636adb
--- /dev/null
+++ b/spec/ruby/core/float/negative_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper'
+
+describe "Float#negative?" do
+  describe "on positive numbers" do
+    it "returns false" do
+      0.1.negative?.should == false
+    end
+  end
+
+  describe "on zero" do
+    it "returns false" do
+      0.0.negative?.should == false
+    end
+  end
+
+  describe "on negative zero" do
+    it "returns false" do
+      -0.0.negative?.should == false
+    end
+  end
+
+  describe "on negative numbers" do
+    it "returns true" do
+      -0.1.negative?.should == true
+    end
+  end
+
+  describe "on NaN" do
+    it "returns false" do
+      nan_value.negative?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/float/next_float_spec.rb b/spec/ruby/core/float/next_float_spec.rb
index 2f0eff605a..59892be343 100644
--- a/spec/ruby/core/float/next_float_spec.rb
+++ b/spec/ruby/core/float/next_float_spec.rb
@@ -9,7 +9,7 @@ describe "Float#next_float" do
     barely_positive.should < barely_positive.next_float
 
     midpoint = barely_positive / 2
-    [0.0, barely_positive].should include midpoint
+    [0.0, barely_positive].should.include? midpoint
   end
 
   it "returns Float::INFINITY for Float::INFINITY" do
@@ -44,6 +44,6 @@ describe "Float#next_float" do
   end
 
   it "returns NAN if NAN was the receiver" do
-    Float::NAN.next_float.nan?.should == true
+    Float::NAN.next_float.should.nan?
   end
 end
diff --git a/spec/ruby/core/float/numerator_spec.rb b/spec/ruby/core/float/numerator_spec.rb
index 7832e8f056..53b32fdd3d 100644
--- a/spec/ruby/core/float/numerator_spec.rb
+++ b/spec/ruby/core/float/numerator_spec.rb
@@ -15,7 +15,7 @@ describe "Float#numerator" do
 
   it "converts self to a Rational object then returns its numerator" do
     @numbers.each do |number|
-      number.infinite?.should be_nil
+      number.infinite?.should == nil
       number.numerator.should == Rational(number).numerator
     end
   end
@@ -25,7 +25,7 @@ describe "Float#numerator" do
   end
 
   it "returns NaN for NaN" do
-    nan_value.numerator.nan?.should be_true
+    nan_value.numerator.nan?.should == true
   end
 
   it "returns Infinity for Infinity" do
diff --git a/spec/ruby/core/float/plus_spec.rb b/spec/ruby/core/float/plus_spec.rb
index 06b136a06b..e3e19d7f39 100644
--- a/spec/ruby/core/float/plus_spec.rb
+++ b/spec/ruby/core/float/plus_spec.rb
@@ -6,7 +6,7 @@ describe "Float#+" do
 
   it "returns self plus other" do
     (491.213 + 2).should be_close(493.213, TOLERANCE)
-    (9.99 + bignum_value).should be_close(9223372036854775808.000, TOLERANCE)
+    (9.99 + bignum_value).should be_close(18446744073709551616.0, TOLERANCE)
     (1001.99 + 5.219).should be_close(1007.209, TOLERANCE)
   end
 end
diff --git a/spec/ruby/core/float/positive_spec.rb b/spec/ruby/core/float/positive_spec.rb
new file mode 100644
index 0000000000..aa87c03151
--- /dev/null
+++ b/spec/ruby/core/float/positive_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper'
+
+describe "Float#positive?" do
+  describe "on positive numbers" do
+    it "returns true" do
+      0.1.positive?.should == true
+    end
+  end
+
+  describe "on zero" do
+    it "returns false" do
+      0.0.positive?.should == false
+    end
+  end
+
+  describe "on negative zero" do
+    it "returns false" do
+      -0.0.positive?.should == false
+    end
+  end
+
+  describe "on negative numbers" do
+    it "returns false" do
+      -0.1.positive?.should == false
+    end
+  end
+
+  describe "on NaN" do
+    it "returns false" do
+      nan_value.positive?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/float/prev_float_spec.rb b/spec/ruby/core/float/prev_float_spec.rb
index 40fcc25a6d..2d1f136254 100644
--- a/spec/ruby/core/float/prev_float_spec.rb
+++ b/spec/ruby/core/float/prev_float_spec.rb
@@ -9,7 +9,7 @@ describe "Float#prev_float" do
     barely_negative.should > barely_negative.prev_float
 
     midpoint = barely_negative / 2
-    [0.0, barely_negative].should include midpoint
+    [0.0, barely_negative].should.include? midpoint
   end
 
   it "returns -Float::INFINITY for -Float::INFINITY" do
@@ -44,6 +44,6 @@ describe "Float#prev_float" do
   end
 
   it "returns NAN if NAN was the receiver" do
-    Float::NAN.prev_float.nan?.should == true
+    Float::NAN.prev_float.should.nan?
   end
 end
diff --git a/spec/ruby/core/float/rationalize_spec.rb b/spec/ruby/core/float/rationalize_spec.rb
index 0c5bef7ac4..fa8fb5c841 100644
--- a/spec/ruby/core/float/rationalize_spec.rb
+++ b/spec/ruby/core/float/rationalize_spec.rb
@@ -29,15 +29,15 @@ describe "Float#rationalize" do
   end
 
   it "raises a FloatDomainError for Infinity" do
-    -> {infinity_value.rationalize}.should raise_error(FloatDomainError)
+    -> {infinity_value.rationalize}.should.raise(FloatDomainError)
   end
 
   it "raises a FloatDomainError for NaN" do
-    -> { nan_value.rationalize }.should raise_error(FloatDomainError)
+    -> { nan_value.rationalize }.should.raise(FloatDomainError)
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { 0.3.rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { 0.3.rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { 0.3.rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { 0.3.rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/float/round_spec.rb b/spec/ruby/core/float/round_spec.rb
index e143682362..63c1d5689c 100644
--- a/spec/ruby/core/float/round_spec.rb
+++ b/spec/ruby/core/float/round_spec.rb
@@ -16,51 +16,57 @@ describe "Float#round" do
   end
 
   it "raises FloatDomainError for exceptional values" do
-    -> { (+infinity_value).round }.should raise_error(FloatDomainError)
-    -> { (-infinity_value).round }.should raise_error(FloatDomainError)
-    -> { nan_value.round }.should raise_error(FloatDomainError)
+    -> { (+infinity_value).round }.should.raise(FloatDomainError)
+    -> { (-infinity_value).round }.should.raise(FloatDomainError)
+    -> { nan_value.round }.should.raise(FloatDomainError)
   end
 
   it "rounds self to an optionally given precision" do
-    5.5.round(0).should eql(6)
-    5.7.round(1).should eql(5.7)
+    5.5.round(0).should.eql?(6)
+    5.7.round(1).should.eql?(5.7)
     1.2345678.round(2).should == 1.23
-    123456.78.round(-2).should eql(123500) # rounded up
-    -123456.78.round(-2).should eql(-123500)
+    123456.78.round(-2).should.eql?(123500) # rounded up
+    -123456.78.round(-2).should.eql?(-123500)
     12.345678.round(3.999).should == 12.346
   end
 
+  it "correctly rounds exact floats with a numerous digits in a fraction part" do
+    0.8241000000000004.round(10).should == 0.8241
+    0.8241000000000002.round(10).should == 0.8241
+  end
+
   it "returns zero when passed a negative argument with magnitude greater than magnitude of the whole number portion of the Float" do
-    0.8346268.round(-1).should eql(0)
+    0.8346268.round(-1).should.eql?(0)
   end
 
   it "raises a TypeError when its argument can not be converted to an Integer" do
-    -> { 1.0.round("4") }.should raise_error(TypeError)
-    -> { 1.0.round(nil) }.should raise_error(TypeError)
+    -> { 1.0.round("4") }.should.raise(TypeError)
+    -> { 1.0.round(nil) }.should.raise(TypeError)
   end
 
   it "raises FloatDomainError for exceptional values when passed a non-positive precision" do
-    -> { Float::INFINITY.round( 0) }.should raise_error(FloatDomainError)
-    -> { Float::INFINITY.round(-2) }.should raise_error(FloatDomainError)
-    -> { (-Float::INFINITY).round( 0) }.should raise_error(FloatDomainError)
-    -> { (-Float::INFINITY).round(-2) }.should raise_error(FloatDomainError)
+    -> { Float::INFINITY.round( 0) }.should.raise(FloatDomainError)
+    -> { Float::INFINITY.round(-2) }.should.raise(FloatDomainError)
+    -> { (-Float::INFINITY).round( 0) }.should.raise(FloatDomainError)
+    -> { (-Float::INFINITY).round(-2) }.should.raise(FloatDomainError)
   end
 
   it "raises RangeError for NAN when passed a non-positive precision" do
-    -> { Float::NAN.round(0) }.should raise_error(RangeError)
-    -> { Float::NAN.round(-2) }.should raise_error(RangeError)
+    -> { Float::NAN.round(0) }.should.raise(RangeError)
+    -> { Float::NAN.round(-2) }.should.raise(RangeError)
   end
 
   it "returns self for exceptional values when passed a non-negative precision" do
     Float::INFINITY.round(2).should == Float::INFINITY
     (-Float::INFINITY).round(2).should == -Float::INFINITY
-    Float::NAN.round(2).should be_nan
+    Float::NAN.round(2).should.nan?
   end
 
   # redmine:5227
   it "works for corner cases" do
-    42.0.round(308).should eql(42.0)
-    1.0e307.round(2).should eql(1.0e307)
+    42.0.round(308).should.eql?(42.0)
+    1.0e307.round(2).should.eql?(1.0e307)
+    120.0.round(-1).should.eql?(120)
   end
 
   # redmine:5271
@@ -68,50 +74,135 @@ describe "Float#round" do
     0.42.round(2.0**30).should == 0.42
   end
 
+  it "returns rounded values for not so big argument" do
+    0.42.round(2.0**23).should == 0.42
+  end
+
   it "returns big values rounded to nearest" do
-    +2.5e20.round(-20).should   eql( +3 * 10 ** 20  )
-    -2.5e20.round(-20).should   eql( -3 * 10 ** 20  )
+    +2.5e20.round(-20).should.eql?( +3 * 10 ** 20  )
+    -2.5e20.round(-20).should.eql?( -3 * 10 ** 20  )
   end
 
   # redmine #5272
   it "returns rounded values for big values" do
-    +2.4e20.round(-20).should   eql( +2 * 10 ** 20  )
-    -2.4e20.round(-20).should   eql( -2 * 10 ** 20  )
-    +2.5e200.round(-200).should eql( +3 * 10 ** 200 )
-    +2.4e200.round(-200).should eql( +2 * 10 ** 200 )
-    -2.5e200.round(-200).should eql( -3 * 10 ** 200 )
-    -2.4e200.round(-200).should eql( -2 * 10 ** 200 )
+    +2.4e20.round(-20).should.eql?( +2 * 10 ** 20  )
+    -2.4e20.round(-20).should.eql?( -2 * 10 ** 20  )
+    +2.5e200.round(-200).should.eql?( +3 * 10 ** 200 )
+    +2.4e200.round(-200).should.eql?( +2 * 10 ** 200 )
+    -2.5e200.round(-200).should.eql?( -3 * 10 ** 200 )
+    -2.4e200.round(-200).should.eql?( -2 * 10 ** 200 )
   end
 
   it "returns different rounded values depending on the half option" do
-    2.5.round(half: nil).should      eql(3)
-    2.5.round(half: :up).should      eql(3)
-    2.5.round(half: :down).should    eql(2)
-    2.5.round(half: :even).should    eql(2)
-    3.5.round(half: nil).should      eql(4)
-    3.5.round(half: :up).should      eql(4)
-    3.5.round(half: :down).should    eql(3)
-    3.5.round(half: :even).should    eql(4)
-    (-2.5).round(half: nil).should   eql(-3)
-    (-2.5).round(half: :up).should   eql(-3)
-    (-2.5).round(half: :down).should eql(-2)
-    (-2.5).round(half: :even).should eql(-2)
+    2.5.round(half: nil).should.eql?(3)
+    2.5.round(half: :up).should.eql?(3)
+    2.5.round(half: :down).should.eql?(2)
+    2.5.round(half: :even).should.eql?(2)
+    3.5.round(half: nil).should.eql?(4)
+    3.5.round(half: :up).should.eql?(4)
+    3.5.round(half: :down).should.eql?(3)
+    3.5.round(half: :even).should.eql?(4)
+    (-2.5).round(half: nil).should.eql?(-3)
+    (-2.5).round(half: :up).should.eql?(-3)
+    (-2.5).round(half: :down).should.eql?(-2)
+    (-2.5).round(half: :even).should.eql?(-2)
   end
 
   it "rounds self to an optionally given precision with a half option" do
-    5.55.round(1, half: nil).should eql(5.6)
-    5.55.round(1, half: :up).should eql(5.6)
-    5.55.round(1, half: :down).should eql(5.5)
-    5.55.round(1, half: :even).should eql(5.6)
+    5.55.round(1, half: nil).should.eql?(5.6)
+    5.55.round(1, half: :up).should.eql?(5.6)
+    5.55.round(1, half: :down).should.eql?(5.5)
+    5.55.round(1, half: :even).should.eql?(5.6)
+    -5.55.round(1, half: nil).should.eql?(-5.6)
+    -5.55.round(1, half: :up).should.eql?(-5.6)
+    -5.55.round(1, half: :down).should.eql?(-5.5)
+    -5.55.round(1, half: :even).should.eql?(-5.6)
+  end
+
+  it "preserves cases where neighbouring floating pointer number increase the decimal places" do
+    4.8100000000000005.round(5, half: nil).should.eql?(4.81)
+    4.8100000000000005.round(5, half: :up).should.eql?(4.81)
+    4.8100000000000005.round(5, half: :down).should.eql?(4.81)
+    4.8100000000000005.round(5, half: :even).should.eql?(4.81)
+    -4.8100000000000005.round(5, half: nil).should.eql?(-4.81)
+    -4.8100000000000005.round(5, half: :up).should.eql?(-4.81)
+    -4.8100000000000005.round(5, half: :down).should.eql?(-4.81)
+    -4.8100000000000005.round(5, half: :even).should.eql?(-4.81)
+    4.81.round(5, half: nil).should.eql?(4.81)
+    4.81.round(5, half: :up).should.eql?(4.81)
+    4.81.round(5, half: :down).should.eql?(4.81)
+    4.81.round(5, half: :even).should.eql?(4.81)
+    -4.81.round(5, half: nil).should.eql?(-4.81)
+    -4.81.round(5, half: :up).should.eql?(-4.81)
+    -4.81.round(5, half: :down).should.eql?(-4.81)
+    -4.81.round(5, half: :even).should.eql?(-4.81)
+    4.809999999999999.round(5, half: nil).should.eql?(4.81)
+    4.809999999999999.round(5, half: :up).should.eql?(4.81)
+    4.809999999999999.round(5, half: :down).should.eql?(4.81)
+    4.809999999999999.round(5, half: :even).should.eql?(4.81)
+    -4.809999999999999.round(5, half: nil).should.eql?(-4.81)
+    -4.809999999999999.round(5, half: :up).should.eql?(-4.81)
+    -4.809999999999999.round(5, half: :down).should.eql?(-4.81)
+    -4.809999999999999.round(5, half: :even).should.eql?(-4.81)
+  end
+
+  # These numbers are neighbouring floating point numbers round a
+  # precise value. They test that the rounding modes work correctly
+  # round that value and precision is not lost which might cause
+  # incorrect results.
+  it "does not lose precision during the rounding process" do
+    767573.1875850001.round(5, half: nil).should.eql?(767573.18759)
+    767573.1875850001.round(5, half: :up).should.eql?(767573.18759)
+    767573.1875850001.round(5, half: :down).should.eql?(767573.18759)
+    767573.1875850001.round(5, half: :even).should.eql?(767573.18759)
+    -767573.1875850001.round(5, half: nil).should.eql?(-767573.18759)
+    -767573.1875850001.round(5, half: :up).should.eql?(-767573.18759)
+    -767573.1875850001.round(5, half: :down).should.eql?(-767573.18759)
+    -767573.1875850001.round(5, half: :even).should.eql?(-767573.18759)
+    767573.187585.round(5, half: nil).should.eql?(767573.18759)
+    767573.187585.round(5, half: :up).should.eql?(767573.18759)
+    767573.187585.round(5, half: :down).should.eql?(767573.18758)
+    767573.187585.round(5, half: :even).should.eql?(767573.18758)
+    -767573.187585.round(5, half: nil).should.eql?(-767573.18759)
+    -767573.187585.round(5, half: :up).should.eql?(-767573.18759)
+    -767573.187585.round(5, half: :down).should.eql?(-767573.18758)
+    -767573.187585.round(5, half: :even).should.eql?(-767573.18758)
+    767573.1875849998.round(5, half: nil).should.eql?(767573.18758)
+    767573.1875849998.round(5, half: :up).should.eql?(767573.18758)
+    767573.1875849998.round(5, half: :down).should.eql?(767573.18758)
+    767573.1875849998.round(5, half: :even).should.eql?(767573.18758)
+    -767573.1875849998.round(5, half: nil).should.eql?(-767573.18758)
+    -767573.1875849998.round(5, half: :up).should.eql?(-767573.18758)
+    -767573.1875849998.round(5, half: :down).should.eql?(-767573.18758)
+    -767573.1875849998.round(5, half: :even).should.eql?(-767573.18758)
   end
 
   it "raises FloatDomainError for exceptional values with a half option" do
-    -> { (+infinity_value).round(half: :up) }.should raise_error(FloatDomainError)
-    -> { (-infinity_value).round(half: :down) }.should raise_error(FloatDomainError)
-    -> { nan_value.round(half: :even) }.should raise_error(FloatDomainError)
+    -> { (+infinity_value).round(half: :up) }.should.raise(FloatDomainError)
+    -> { (-infinity_value).round(half: :down) }.should.raise(FloatDomainError)
+    -> { nan_value.round(half: :even) }.should.raise(FloatDomainError)
   end
 
   it "raise for a non-existent round mode" do
-    -> { 14.2.round(half: :nonsense) }.should raise_error(ArgumentError, "invalid rounding mode: nonsense")
+    -> { 14.2.round(half: :nonsense) }.should.raise(ArgumentError, "invalid rounding mode: nonsense")
+  end
+
+  describe "when 0.0 is given" do
+    it "returns self for positive ndigits" do
+      (0.0).round(5).inspect.should == "0.0"
+      (-0.0).round(1).inspect.should == "-0.0"
+    end
+
+    it "returns 0 for 0 or undefined ndigits" do
+      (0.0).round.should == 0
+      (-0.0).round(0).should == 0
+      (0.0).round(half: :up).should == 0
+    end
+
+    it "returns 0 for negative ndigits" do
+      (0.0).round(-1).should == 0
+      (-0.0).round(-1).should == 0
+      (0.0).round(-1, half: :up).should == 0
+    end
   end
 end
diff --git a/spec/ruby/core/float/shared/abs.rb b/spec/ruby/core/float/shared/abs.rb
index 607983322d..ab21480e24 100644
--- a/spec/ruby/core/float/shared/abs.rb
+++ b/spec/ruby/core/float/shared/abs.rb
@@ -16,6 +16,6 @@ describe :float_abs, shared: true do
   end
 
   it "returns NaN if NaN" do
-    nan_value.send(@method).nan?.should be_true
+    nan_value.send(@method).nan?.should == true
   end
 end
diff --git a/spec/ruby/core/float/shared/arg.rb b/spec/ruby/core/float/shared/arg.rb
index 136cf19ec8..de0024313d 100644
--- a/spec/ruby/core/float/shared/arg.rb
+++ b/spec/ruby/core/float/shared/arg.rb
@@ -1,12 +1,12 @@
 describe :float_arg, shared: true do
   it "returns NaN if NaN" do
     f = nan_value
-    f.send(@method).nan?.should be_true
+    f.send(@method).nan?.should == true
   end
 
   it "returns self if NaN" do
     f = nan_value
-    f.send(@method).should equal(f)
+    f.send(@method).should.equal?(f)
   end
 
   it "returns 0 if positive" do
diff --git a/spec/ruby/core/float/shared/arithmetic_exception_in_coerce.rb b/spec/ruby/core/float/shared/arithmetic_exception_in_coerce.rb
index 19a02572d8..bd3bf9019f 100644
--- a/spec/ruby/core/float/shared/arithmetic_exception_in_coerce.rb
+++ b/spec/ruby/core/float/shared/arithmetic_exception_in_coerce.rb
@@ -1,33 +1,11 @@
 require_relative '../fixtures/classes'
 
 describe :float_arithmetic_exception_in_coerce, shared: true do
-  ruby_version_is ""..."2.5" do
-    it "rescues exception (StandardError and subclasses) raised in other#coerce and raises TypeError" do
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
+  it "does not rescue exception raised in other#coerce" do
+    b = mock("numeric with failed #coerce")
+    b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
 
-      # e.g. 1.0 > b
-      -> { 1.0.send(@method, b) }.should raise_error(TypeError, /MockObject can't be coerced into Float/)
-    end
-
-    it "does not rescue Exception and StandardError siblings raised in other#coerce" do
-      [Exception, NoMemoryError].each do |exception|
-        b = mock("numeric with failed #coerce")
-        b.should_receive(:coerce).and_raise(exception)
-
-        # e.g. 1.0 > b
-        -> { 1.0.send(@method, b) }.should raise_error(exception)
-      end
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "does not rescue exception raised in other#coerce" do
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
-
-      # e.g. 1.0 > b
-      -> { 1.0.send(@method, b) }.should raise_error(FloatSpecs::CoerceError)
-    end
+    # e.g. 1.0 > b
+    -> { 1.0.send(@method, b) }.should.raise(FloatSpecs::CoerceError)
   end
 end
diff --git a/spec/ruby/core/float/shared/comparison_exception_in_coerce.rb b/spec/ruby/core/float/shared/comparison_exception_in_coerce.rb
index f8ded53644..eec5d8daf9 100644
--- a/spec/ruby/core/float/shared/comparison_exception_in_coerce.rb
+++ b/spec/ruby/core/float/shared/comparison_exception_in_coerce.rb
@@ -1,35 +1,11 @@
 require_relative '../fixtures/classes'
 
 describe :float_comparison_exception_in_coerce, shared: true do
-  ruby_version_is ""..."2.5" do
-    it "rescues exception (StandardError and subclasses) raised in other#coerce and raises ArgumentError" do
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
+  it "does not rescue exception raised in other#coerce" do
+    b = mock("numeric with failed #coerce")
+    b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
 
-      # e.g. 1.0 > b
-      -> {
-        -> { 1.0.send(@method, b) }.should raise_error(ArgumentError, /comparison of Float with MockObject failed/)
-      }.should complain(/Numerical comparison operators will no more rescue exceptions of #coerce/)
-    end
-
-    it "does not rescue Exception and StandardError siblings raised in other#coerce" do
-      [Exception, NoMemoryError].each do |exception|
-        b = mock("numeric with failed #coerce")
-        b.should_receive(:coerce).and_raise(exception)
-
-        # e.g. 1.0 > b
-        -> { 1.0.send(@method, b) }.should raise_error(exception)
-      end
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "does not rescue exception raised in other#coerce" do
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(FloatSpecs::CoerceError)
-
-      # e.g. 1.0 > b
-      -> { 1.0.send(@method, b) }.should raise_error(FloatSpecs::CoerceError)
-    end
+    # e.g. 1.0 > b
+    -> { 1.0.send(@method, b) }.should.raise(FloatSpecs::CoerceError)
   end
 end
diff --git a/spec/ruby/core/float/shared/equal.rb b/spec/ruby/core/float/shared/equal.rb
index 668aa069b5..4d524e1cf2 100644
--- a/spec/ruby/core/float/shared/equal.rb
+++ b/spec/ruby/core/float/shared/equal.rb
@@ -14,4 +14,25 @@ describe :float_equal, shared: true do
     1.0.send(@method, x).should == false
     2.0.send(@method, x).should == true
   end
+
+  it "returns false if one side is NaN" do
+    [1.0, 42, bignum_value].each { |n|
+      (nan_value.send(@method, n)).should == false
+      (n.send(@method, nan_value)).should == false
+    }
+  end
+
+  it "handles positive infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      (infinity_value.send(@method, n)).should == false
+      (n.send(@method, infinity_value)).should == false
+    }
+  end
+
+  it "handles negative infinity" do
+    [1.0, 42, bignum_value].each { |n|
+      ((-infinity_value).send(@method, n)).should == false
+      (n.send(@method, -infinity_value)).should == false
+    }
+  end
 end
diff --git a/spec/ruby/core/float/shared/modulo.rb b/spec/ruby/core/float/shared/modulo.rb
index 6700bd4f4e..1efee1476d 100644
--- a/spec/ruby/core/float/shared/modulo.rb
+++ b/spec/ruby/core/float/shared/modulo.rb
@@ -16,13 +16,13 @@ describe :float_modulo, shared: true do
   end
 
   it "returns NaN when called on NaN or Infinities" do
-    Float::NAN.send(@method, 42).should be_nan
-    Float::INFINITY.send(@method, 42).should be_nan
-    (-Float::INFINITY).send(@method, 42).should be_nan
+    Float::NAN.send(@method, 42).should.nan?
+    Float::INFINITY.send(@method, 42).should.nan?
+    (-Float::INFINITY).send(@method, 42).should.nan?
   end
 
   it "returns NaN when modulus is NaN" do
-    4.2.send(@method, Float::NAN).should be_nan
+    4.2.send(@method, Float::NAN).should.nan?
   end
 
   it "returns -0.0 when called on -0.0 with a non zero modulus" do
@@ -42,7 +42,7 @@ describe :float_modulo, shared: true do
   end
 
   it "raises a ZeroDivisionError if other is zero" do
-    -> { 1.0.send(@method, 0) }.should raise_error(ZeroDivisionError)
-    -> { 1.0.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
+    -> { 1.0.send(@method, 0) }.should.raise(ZeroDivisionError)
+    -> { 1.0.send(@method, 0.0) }.should.raise(ZeroDivisionError)
   end
 end
diff --git a/spec/ruby/core/float/shared/quo.rb b/spec/ruby/core/float/shared/quo.rb
index 3487824f70..930187aaf7 100644
--- a/spec/ruby/core/float/shared/quo.rb
+++ b/spec/ruby/core/float/shared/quo.rb
@@ -1,9 +1,9 @@
 describe :float_quo, shared: true do
-  it "performs floating-point division between self and a Fixnum" do
+  it "performs floating-point division between self and an Integer" do
     8.9.send(@method, 7).should == 1.2714285714285716
   end
 
-  it "performs floating-point division between self and a Bignum" do
+  it "performs floating-point division between self and an Integer" do
     8.9.send(@method, 9999999999999**9).should == 8.900000000008011e-117
   end
 
@@ -12,8 +12,8 @@ describe :float_quo, shared: true do
   end
 
   it "returns NaN when the argument is NaN" do
-    -1819.999999.send(@method, nan_value).nan?.should be_true
-    11109.1981271.send(@method, nan_value).nan?.should be_true
+    -1819.999999.send(@method, nan_value).nan?.should == true
+    11109.1981271.send(@method, nan_value).nan?.should == true
   end
 
   it "returns Infinity when the argument is 0.0" do
@@ -50,10 +50,10 @@ describe :float_quo, shared: true do
   end
 
   it "raises a TypeError when argument isn't numeric" do
-    -> { 27292.2.send(@method, mock('non-numeric')) }.should raise_error(TypeError)
+    -> { 27292.2.send(@method, mock('non-numeric')) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when passed multiple arguments" do
-    -> { 272.221.send(@method, 6,0.2) }.should raise_error(ArgumentError)
+    -> { 272.221.send(@method, 6,0.2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/float/shared/to_i.rb b/spec/ruby/core/float/shared/to_i.rb
index 960295f095..1e6f941467 100644
--- a/spec/ruby/core/float/shared/to_i.rb
+++ b/spec/ruby/core/float/shared/to_i.rb
@@ -1,10 +1,14 @@
 describe :float_to_i, shared: true do
   it "returns self truncated to an Integer" do
-    899.2.send(@method).should eql(899)
-    -1.122256e-45.send(@method).should eql(0)
-    5_213_451.9201.send(@method).should eql(5213451)
-    1.233450999123389e+12.send(@method).should eql(1233450999123)
-    -9223372036854775808.1.send(@method).should eql(-9223372036854775808)
-    9223372036854775808.1.send(@method).should eql(9223372036854775808)
+    899.2.send(@method).should.eql?(899)
+    -1.122256e-45.send(@method).should.eql?(0)
+    5_213_451.9201.send(@method).should.eql?(5213451)
+    1.233450999123389e+12.send(@method).should.eql?(1233450999123)
+    -9223372036854775808.1.send(@method).should.eql?(-9223372036854775808)
+    9223372036854775808.1.send(@method).should.eql?(9223372036854775808)
+  end
+
+  it "raises a FloatDomainError for NaN" do
+    -> { nan_value.send(@method) }.should.raise(FloatDomainError)
   end
 end
diff --git a/spec/ruby/core/float/shared/to_s.rb b/spec/ruby/core/float/shared/to_s.rb
new file mode 100644
index 0000000000..81ffdd9e81
--- /dev/null
+++ b/spec/ruby/core/float/shared/to_s.rb
@@ -0,0 +1,308 @@
+describe :float_to_s, shared: true do
+  it "returns 'NaN' for NaN" do
+    nan_value().send(@method).should == 'NaN'
+  end
+
+  it "returns 'Infinity' for positive infinity" do
+    infinity_value().send(@method).should == 'Infinity'
+  end
+
+  it "returns '-Infinity' for negative infinity" do
+    (-infinity_value()).send(@method).should == '-Infinity'
+  end
+
+  it "returns '0.0' for 0.0" do
+    0.0.send(@method).should == "0.0"
+  end
+
+  platform_is_not :openbsd do
+    it "emits '-' for -0.0" do
+      -0.0.send(@method).should == "-0.0"
+    end
+  end
+
+  it "emits a '-' for negative values" do
+    -3.14.send(@method).should == "-3.14"
+  end
+
+  it "emits a trailing '.0' for a whole number" do
+    50.0.send(@method).should == "50.0"
+  end
+
+  it "emits a trailing '.0' for the mantissa in e format" do
+    1.0e20.send(@method).should == "1.0e+20"
+  end
+
+  it "uses non-e format for a positive value with fractional part having 5 significant figures" do
+    0.0001.send(@method).should == "0.0001"
+  end
+
+  it "uses non-e format for a negative value with fractional part having 5 significant figures" do
+    -0.0001.send(@method).should == "-0.0001"
+  end
+
+  it "uses e format for a positive value with fractional part having 6 significant figures" do
+    0.00001.send(@method).should == "1.0e-05"
+  end
+
+  it "uses e format for a negative value with fractional part having 6 significant figures" do
+    -0.00001.send(@method).should == "-1.0e-05"
+  end
+
+  it "uses non-e format for a positive value with whole part having 15 significant figures" do
+    10000000000000.0.send(@method).should == "10000000000000.0"
+  end
+
+  it "uses non-e format for a negative value with whole part having 15 significant figures" do
+    -10000000000000.0.send(@method).should == "-10000000000000.0"
+  end
+
+  it "uses non-e format for a positive value with whole part having 16 significant figures" do
+    100000000000000.0.send(@method).should == "100000000000000.0"
+  end
+
+  it "uses non-e format for a negative value with whole part having 16 significant figures" do
+    -100000000000000.0.send(@method).should == "-100000000000000.0"
+  end
+
+  it "uses e format for a positive value with whole part having 18 significant figures" do
+    10000000000000000.0.send(@method).should == "1.0e+16"
+  end
+
+  it "uses e format for a negative value with whole part having 18 significant figures" do
+    -10000000000000000.0.send(@method).should == "-1.0e+16"
+  end
+
+  it "uses e format for a positive value with whole part having 17 significant figures" do
+    1000000000000000.0.send(@method).should == "1.0e+15"
+  end
+
+  it "uses e format for a negative value with whole part having 17 significant figures" do
+    -1000000000000000.0.send(@method).should == "-1.0e+15"
+  end
+
+  # #3273
+  it "outputs the minimal, unique form necessary to recreate the value" do
+    value = 0.21611564636388508
+    string = "0.21611564636388508"
+
+    value.send(@method).should == string
+    string.to_f.should == value
+  end
+
+  it "outputs the minimal, unique form to represent the value" do
+    0.56.send(@method).should == "0.56"
+  end
+
+  describe "matches" do
+    it "random examples in all ranges" do
+      # 50.times do
+      #   bytes = (0...8).map { rand(256) }
+      #   string = bytes.pack('C8')
+      #   float = string.unpack('D').first
+      #   puts "#{'%.20g' % float}.send(@method).should == #{float.send(@method).inspect}"
+      # end
+
+      2.5540217314354050325e+163.send(@method).should == "2.554021731435405e+163"
+      2.5492588360356597544e-172.send(@method).should == "2.5492588360356598e-172"
+      1.742770260934704852e-82.send(@method).should == "1.7427702609347049e-82"
+      6.2108093676180883209e-104.send(@method).should == "6.210809367618088e-104"
+      -3.3448803488331067402e-143.send(@method).should == "-3.3448803488331067e-143"
+      -2.2740074343500832557e-168.send(@method).should == "-2.2740074343500833e-168"
+      7.0587971678048535732e+191.send(@method).should == "7.058797167804854e+191"
+      -284438.88327586348169.send(@method).should == "-284438.8832758635"
+      3.953272468476091301e+105.send(@method).should == "3.9532724684760913e+105"
+      -3.6361359552959847853e+100.send(@method).should == "-3.636135955295985e+100"
+      -1.3222325865575206185e-31.send(@method).should == "-1.3222325865575206e-31"
+      1.1440138916932761366e+130.send(@method).should == "1.1440138916932761e+130"
+      4.8750891560387561157e-286.send(@method).should == "4.875089156038756e-286"
+      5.6101113356591453525e-257.send(@method).should == "5.610111335659145e-257"
+      -3.829644279545809575e-100.send(@method).should == "-3.8296442795458096e-100"
+      1.5342839401396406117e-194.send(@method).should == "1.5342839401396406e-194"
+      2.2284972755169921402e-144.send(@method).should == "2.228497275516992e-144"
+      2.1825655917065601737e-61.send(@method).should == "2.1825655917065602e-61"
+      -2.6672271363524338322e-62.send(@method).should == "-2.667227136352434e-62"
+      -1.9257995160119059415e+21.send(@method).should == "-1.925799516011906e+21"
+      -8.9096732962887121718e-198.send(@method).should == "-8.909673296288712e-198"
+      2.0202075376548644959e-90.send(@method).should == "2.0202075376548645e-90"
+      -7.7341602581786258961e-266.send(@method).should == "-7.734160258178626e-266"
+      3.5134482598733635046e+98.send(@method).should == "3.5134482598733635e+98"
+      -2.124411722371029134e+154.send(@method).should == "-2.124411722371029e+154"
+      -4.573908787355718687e+110.send(@method).should == "-4.573908787355719e+110"
+      -1.9344425934170969879e-232.send(@method).should == "-1.934442593417097e-232"
+      -1.3274227399979271095e+171.send(@method).should == "-1.3274227399979271e+171"
+      9.3495270482104442383e-283.send(@method).should == "9.349527048210444e-283"
+      -4.2046059371986483233e+307.send(@method).should == "-4.2046059371986483e+307"
+      3.6133547278583543004e-117.send(@method).should == "3.613354727858354e-117"
+      4.9247416523566613499e-08.send(@method).should == "4.9247416523566613e-08"
+      1.6936145488250064007e-71.send(@method).should == "1.6936145488250064e-71"
+      2.4455483206829433098e+96.send(@method).should == "2.4455483206829433e+96"
+      7.9797449851436455384e+124.send(@method).should == "7.979744985143646e+124"
+      -1.3873689634457876774e-129.send(@method).should == "-1.3873689634457877e-129"
+      3.9761102037533483075e+284.send(@method).should == "3.976110203753348e+284"
+      -4.2819791952139402486e-303.send(@method).should == "-4.28197919521394e-303"
+      -5.7981017546689831298e-116.send(@method).should == "-5.798101754668983e-116"
+      -3.953266497860534199e-28.send(@method).should == "-3.953266497860534e-28"
+      -2.0659852720290440959e-243.send(@method).should == "-2.065985272029044e-243"
+      8.9670488995878688018e-05.send(@method).should == "8.967048899587869e-05"
+      -1.2317943708113061768e-98.send(@method).should == "-1.2317943708113062e-98"
+      -3.8930768307633080463e+248.send(@method).should == "-3.893076830763308e+248"
+      6.5854032671803925627e-239.send(@method).should == "6.5854032671803926e-239"
+      4.6257022188980878952e+177.send(@method).should == "4.625702218898088e+177"
+      -1.9397155125507235603e-187.send(@method).should == "-1.9397155125507236e-187"
+      8.5752156951245705056e+117.send(@method).should == "8.57521569512457e+117"
+      -2.4784875958162501671e-132.send(@method).should == "-2.4784875958162502e-132"
+      -4.4125691841230058457e-203.send(@method).should == "-4.412569184123006e-203"
+    end
+
+    it "random examples in human ranges" do
+      # 50.times do
+      #   formatted = ''
+      #   rand(1..3).times do
+      #     formatted << rand(10).to_s
+      #   end
+      #   formatted << '.'
+      #   rand(1..9).times do
+      #     formatted << rand(10).to_s
+      #   end
+      #   float = formatted.to_f
+      #   puts "#{'%.20f' % float}.send(@method).should == #{float.send(@method).inspect}"
+      # end
+
+      5.17869899999999994122.send(@method).should == "5.178699"
+      905.62695729999995819526.send(@method).should == "905.6269573"
+      62.75999999999999801048.send(@method).should == "62.76"
+      6.93856795800000014651.send(@method).should == "6.938567958"
+      4.95999999999999996447.send(@method).should == "4.96"
+      32.77993899999999882766.send(@method).should == "32.779939"
+      544.12756779999995160324.send(@method).should == "544.1275678"
+      66.25801119999999855281.send(@method).should == "66.2580112"
+      7.90000000000000035527.send(@method).should == "7.9"
+      5.93100000000000004974.send(@method).should == "5.931"
+      5.21229313600000043749.send(@method).should == "5.212293136"
+      503.44173809000000119340.send(@method).should == "503.44173809"
+      79.26000000000000511591.send(@method).should == "79.26"
+      8.51524999999999998579.send(@method).should == "8.51525"
+      174.00000000000000000000.send(@method).should == "174.0"
+      50.39580000000000126192.send(@method).should == "50.3958"
+      35.28999999999999914735.send(@method).should == "35.29"
+      5.43136675399999990788.send(@method).should == "5.431366754"
+      654.07680000000004838512.send(@method).should == "654.0768"
+      6.07423700000000010846.send(@method).should == "6.074237"
+      102.25779799999999397642.send(@method).should == "102.257798"
+      5.08129999999999970584.send(@method).should == "5.0813"
+      6.00000000000000000000.send(@method).should == "6.0"
+      8.30000000000000071054.send(@method).should == "8.3"
+      32.68345999999999662577.send(@method).should == "32.68346"
+      581.11170000000004165486.send(@method).should == "581.1117"
+      76.31342999999999676675.send(@method).should == "76.31343"
+      438.30826000000001840817.send(@method).should == "438.30826"
+      482.06631994000002805478.send(@method).should == "482.06631994"
+      55.92721026899999969828.send(@method).should == "55.927210269"
+      4.00000000000000000000.send(@method).should == "4.0"
+      55.86693999999999959982.send(@method).should == "55.86694"
+      787.98299999999994724931.send(@method).should == "787.983"
+      5.73810511000000023074.send(@method).should == "5.73810511"
+      74.51926810000000500622.send(@method).should == "74.5192681"
+      892.89999999999997726263.send(@method).should == "892.9"
+      68.27299999999999613465.send(@method).should == "68.273"
+      904.10000000000002273737.send(@method).should == "904.1"
+      5.23200000000000020606.send(@method).should == "5.232"
+      4.09628000000000014325.send(@method).should == "4.09628"
+      46.05152633699999853434.send(@method).should == "46.051526337"
+      142.12884990599999923688.send(@method).should == "142.128849906"
+      3.83057023500000015659.send(@method).should == "3.830570235"
+      11.81684594699999912848.send(@method).should == "11.816845947"
+      80.50000000000000000000.send(@method).should == "80.5"
+      382.18215010000000120272.send(@method).should == "382.1821501"
+      55.38444606899999911320.send(@method).should == "55.384446069"
+      5.78000000000000024869.send(@method).should == "5.78"
+      2.88244999999999995666.send(@method).should == "2.88245"
+      43.27709999999999723741.send(@method).should == "43.2771"
+    end
+
+    it "random values from divisions" do
+      (1.0 / 7).send(@method).should == "0.14285714285714285"
+
+      # 50.times do
+      #    a = rand(10)
+      #    b = rand(10)
+      #    c = rand(10)
+      #    d = rand(10)
+      #    expression = "#{a}.#{b} / #{c}.#{d}"
+      #    puts "      (#{expression}).send(@method).should == #{eval(expression).send(@method).inspect}"
+      #  end
+
+      (1.1 / 7.1).send(@method).should == "0.15492957746478875"
+      (6.5 / 8.8).send(@method).should == "0.7386363636363635"
+      (4.8 / 4.3).send(@method).should == "1.1162790697674418"
+      (4.0 / 1.9).send(@method).should == "2.1052631578947367"
+      (9.1 / 0.8).send(@method).should == "11.374999999999998"
+      (5.3 / 7.5).send(@method).should == "0.7066666666666667"
+      (2.8 / 1.8).send(@method).should == "1.5555555555555554"
+      (2.1 / 2.5).send(@method).should == "0.8400000000000001"
+      (3.5 / 6.0).send(@method).should == "0.5833333333333334"
+      (4.6 / 0.3).send(@method).should == "15.333333333333332"
+      (0.6 / 2.4).send(@method).should == "0.25"
+      (1.3 / 9.1).send(@method).should == "0.14285714285714288"
+      (0.3 / 5.0).send(@method).should == "0.06"
+      (5.0 / 4.2).send(@method).should == "1.1904761904761905"
+      (3.0 / 2.0).send(@method).should == "1.5"
+      (6.3 / 2.0).send(@method).should == "3.15"
+      (5.4 / 6.0).send(@method).should == "0.9"
+      (9.6 / 8.1).send(@method).should == "1.1851851851851851"
+      (8.7 / 1.6).send(@method).should == "5.437499999999999"
+      (1.9 / 7.8).send(@method).should == "0.24358974358974358"
+      (0.5 / 2.1).send(@method).should == "0.23809523809523808"
+      (9.3 / 5.8).send(@method).should == "1.6034482758620692"
+      (2.7 / 8.0).send(@method).should == "0.3375"
+      (9.7 / 7.8).send(@method).should == "1.2435897435897436"
+      (8.1 / 2.4).send(@method).should == "3.375"
+      (7.7 / 2.7).send(@method).should == "2.8518518518518516"
+      (7.9 / 1.7).send(@method).should == "4.647058823529412"
+      (6.5 / 8.2).send(@method).should == "0.7926829268292683"
+      (7.8 / 9.6).send(@method).should == "0.8125"
+      (2.2 / 4.6).send(@method).should == "0.47826086956521746"
+      (0.0 / 1.0).send(@method).should == "0.0"
+      (8.3 / 2.9).send(@method).should == "2.8620689655172415"
+      (3.1 / 6.1).send(@method).should == "0.5081967213114754"
+      (2.8 / 7.8).send(@method).should == "0.358974358974359"
+      (8.0 / 0.1).send(@method).should == "80.0"
+      (1.7 / 6.4).send(@method).should == "0.265625"
+      (1.8 / 5.4).send(@method).should == "0.3333333333333333"
+      (8.0 / 5.8).send(@method).should == "1.3793103448275863"
+      (5.2 / 4.1).send(@method).should == "1.2682926829268295"
+      (9.8 / 5.8).send(@method).should == "1.6896551724137934"
+      (5.4 / 9.5).send(@method).should == "0.5684210526315789"
+      (8.4 / 4.9).send(@method).should == "1.7142857142857142"
+      (1.7 / 3.5).send(@method).should == "0.4857142857142857"
+      (1.2 / 5.1).send(@method).should == "0.23529411764705882"
+      (1.4 / 2.0).send(@method).should == "0.7"
+      (4.8 / 8.0).send(@method).should == "0.6"
+      (9.0 / 2.5).send(@method).should == "3.6"
+      (0.2 / 0.6).send(@method).should == "0.33333333333333337"
+      (7.8 / 5.2).send(@method).should == "1.5"
+      (9.5 / 5.5).send(@method).should == "1.7272727272727273"
+    end
+  end
+
+  describe 'encoding' do
+    before :each do
+      @internal = Encoding.default_internal
+    end
+
+    after :each do
+      Encoding.default_internal = @internal
+    end
+
+    it "returns a String in US-ASCII encoding when Encoding.default_internal is nil" do
+      Encoding.default_internal = nil
+      1.23.send(@method).encoding.should.equal?(Encoding::US_ASCII)
+    end
+
+    it "returns a String in US-ASCII encoding when Encoding.default_internal is not nil" do
+      Encoding.default_internal = Encoding::IBM437
+      5.47.send(@method).encoding.should.equal?(Encoding::US_ASCII)
+    end
+  end
+end
diff --git a/spec/ruby/core/float/to_s_spec.rb b/spec/ruby/core/float/to_s_spec.rb
index ad04bc4fb6..6727a883f8 100644
--- a/spec/ruby/core/float/to_s_spec.rb
+++ b/spec/ruby/core/float/to_s_spec.rb
@@ -1,310 +1,6 @@
 require_relative '../../spec_helper'
+require_relative 'shared/to_s'
 
 describe "Float#to_s" do
-  it "returns 'NaN' for NaN" do
-    nan_value().to_s.should == 'NaN'
-  end
-
-  it "returns 'Infinity' for positive infinity" do
-    infinity_value().to_s.should == 'Infinity'
-  end
-
-  it "returns '-Infinity' for negative infinity" do
-    (-infinity_value()).to_s.should == '-Infinity'
-  end
-
-  it "returns '0.0' for 0.0" do
-    0.0.to_s.should == "0.0"
-  end
-
-  platform_is_not :openbsd do
-    it "emits '-' for -0.0" do
-      -0.0.to_s.should == "-0.0"
-    end
-  end
-
-  it "emits a '-' for negative values" do
-    -3.14.to_s.should == "-3.14"
-  end
-
-  it "emits a trailing '.0' for a whole number" do
-    50.0.to_s.should == "50.0"
-  end
-
-  it "emits a trailing '.0' for the mantissa in e format" do
-    1.0e20.to_s.should == "1.0e+20"
-  end
-
-  it "uses non-e format for a positive value with fractional part having 5 significant figures" do
-    0.0001.to_s.should == "0.0001"
-  end
-
-  it "uses non-e format for a negative value with fractional part having 5 significant figures" do
-    -0.0001.to_s.should == "-0.0001"
-  end
-
-  it "uses e format for a positive value with fractional part having 6 significant figures" do
-    0.00001.to_s.should == "1.0e-05"
-  end
-
-  it "uses e format for a negative value with fractional part having 6 significant figures" do
-    -0.00001.to_s.should == "-1.0e-05"
-  end
-
-  it "uses non-e format for a positive value with whole part having 15 significant figures" do
-    10000000000000.0.to_s.should == "10000000000000.0"
-  end
-
-  it "uses non-e format for a negative value with whole part having 15 significant figures" do
-    -10000000000000.0.to_s.should == "-10000000000000.0"
-  end
-
-  it "uses non-e format for a positive value with whole part having 16 significant figures" do
-    100000000000000.0.to_s.should == "100000000000000.0"
-  end
-
-  it "uses non-e format for a negative value with whole part having 16 significant figures" do
-    -100000000000000.0.to_s.should == "-100000000000000.0"
-  end
-
-  it "uses e format for a positive value with whole part having 18 significant figures" do
-    10000000000000000.0.to_s.should == "1.0e+16"
-  end
-
-  it "uses e format for a negative value with whole part having 18 significant figures" do
-    -10000000000000000.0.to_s.should == "-1.0e+16"
-  end
-
-  it "uses e format for a positive value with whole part having 17 significant figures" do
-    1000000000000000.0.to_s.should == "1.0e+15"
-  end
-
-  it "uses e format for a negative value with whole part having 17 significant figures" do
-    -1000000000000000.0.to_s.should == "-1.0e+15"
-  end
-
-  # #3273
-  it "outputs the minimal, unique form necessary to recreate the value" do
-    value = 0.21611564636388508
-    string = "0.21611564636388508"
-
-    value.to_s.should == string
-    string.to_f.should == value
-  end
-
-  it "outputs the minimal, unique form to represent the value" do
-    0.56.to_s.should == "0.56"
-  end
-
-  describe "matches" do
-    it "random examples in all ranges" do
-      # 50.times do
-      #   bytes = (0...8).map { rand(256) }
-      #   string = bytes.pack('C8')
-      #   float = string.unpack('D').first
-      #   puts "#{'%.20g' % float}.to_s.should == #{float.to_s.inspect}"
-      # end
-
-      2.5540217314354050325e+163.to_s.should == "2.554021731435405e+163"
-      2.5492588360356597544e-172.to_s.should == "2.5492588360356598e-172"
-      1.742770260934704852e-82.to_s.should == "1.7427702609347049e-82"
-      6.2108093676180883209e-104.to_s.should == "6.210809367618088e-104"
-      -3.3448803488331067402e-143.to_s.should == "-3.3448803488331067e-143"
-      -2.2740074343500832557e-168.to_s.should == "-2.2740074343500833e-168"
-      7.0587971678048535732e+191.to_s.should == "7.058797167804854e+191"
-      -284438.88327586348169.to_s.should == "-284438.8832758635"
-      3.953272468476091301e+105.to_s.should == "3.9532724684760913e+105"
-      -3.6361359552959847853e+100.to_s.should == "-3.636135955295985e+100"
-      -1.3222325865575206185e-31.to_s.should == "-1.3222325865575206e-31"
-      1.1440138916932761366e+130.to_s.should == "1.1440138916932761e+130"
-      4.8750891560387561157e-286.to_s.should == "4.875089156038756e-286"
-      5.6101113356591453525e-257.to_s.should == "5.610111335659145e-257"
-      -3.829644279545809575e-100.to_s.should == "-3.8296442795458096e-100"
-      1.5342839401396406117e-194.to_s.should == "1.5342839401396406e-194"
-      2.2284972755169921402e-144.to_s.should == "2.228497275516992e-144"
-      2.1825655917065601737e-61.to_s.should == "2.1825655917065602e-61"
-      -2.6672271363524338322e-62.to_s.should == "-2.667227136352434e-62"
-      -1.9257995160119059415e+21.to_s.should == "-1.925799516011906e+21"
-      -8.9096732962887121718e-198.to_s.should == "-8.909673296288712e-198"
-      2.0202075376548644959e-90.to_s.should == "2.0202075376548645e-90"
-      -7.7341602581786258961e-266.to_s.should == "-7.734160258178626e-266"
-      3.5134482598733635046e+98.to_s.should == "3.5134482598733635e+98"
-      -2.124411722371029134e+154.to_s.should == "-2.124411722371029e+154"
-      -4.573908787355718687e+110.to_s.should == "-4.573908787355719e+110"
-      -1.9344425934170969879e-232.to_s.should == "-1.934442593417097e-232"
-      -1.3274227399979271095e+171.to_s.should == "-1.3274227399979271e+171"
-      9.3495270482104442383e-283.to_s.should == "9.349527048210444e-283"
-      -4.2046059371986483233e+307.to_s.should == "-4.2046059371986483e+307"
-      3.6133547278583543004e-117.to_s.should == "3.613354727858354e-117"
-      4.9247416523566613499e-08.to_s.should == "4.9247416523566613e-08"
-      1.6936145488250064007e-71.to_s.should == "1.6936145488250064e-71"
-      2.4455483206829433098e+96.to_s.should == "2.4455483206829433e+96"
-      7.9797449851436455384e+124.to_s.should == "7.979744985143646e+124"
-      -1.3873689634457876774e-129.to_s.should == "-1.3873689634457877e-129"
-      3.9761102037533483075e+284.to_s.should == "3.976110203753348e+284"
-      -4.2819791952139402486e-303.to_s.should == "-4.28197919521394e-303"
-      -5.7981017546689831298e-116.to_s.should == "-5.798101754668983e-116"
-      -3.953266497860534199e-28.to_s.should == "-3.953266497860534e-28"
-      -2.0659852720290440959e-243.to_s.should == "-2.065985272029044e-243"
-      8.9670488995878688018e-05.to_s.should == "8.967048899587869e-05"
-      -1.2317943708113061768e-98.to_s.should == "-1.2317943708113062e-98"
-      -3.8930768307633080463e+248.to_s.should == "-3.893076830763308e+248"
-      6.5854032671803925627e-239.to_s.should == "6.5854032671803926e-239"
-      4.6257022188980878952e+177.to_s.should == "4.625702218898088e+177"
-      -1.9397155125507235603e-187.to_s.should == "-1.9397155125507236e-187"
-      8.5752156951245705056e+117.to_s.should == "8.57521569512457e+117"
-      -2.4784875958162501671e-132.to_s.should == "-2.4784875958162502e-132"
-      -4.4125691841230058457e-203.to_s.should == "-4.412569184123006e-203"
-    end
-
-    it "random examples in human ranges" do
-      # 50.times do
-      #   formatted = ''
-      #   rand(1..3).times do
-      #     formatted << rand(10).to_s
-      #   end
-      #   formatted << '.'
-      #   rand(1..9).times do
-      #     formatted << rand(10).to_s
-      #   end
-      #   float = formatted.to_f
-      #   puts "#{'%.20f' % float}.to_s.should == #{float.to_s.inspect}"
-      # end
-
-      5.17869899999999994122.to_s.should == "5.178699"
-      905.62695729999995819526.to_s.should == "905.6269573"
-      62.75999999999999801048.to_s.should == "62.76"
-      6.93856795800000014651.to_s.should == "6.938567958"
-      4.95999999999999996447.to_s.should == "4.96"
-      32.77993899999999882766.to_s.should == "32.779939"
-      544.12756779999995160324.to_s.should == "544.1275678"
-      66.25801119999999855281.to_s.should == "66.2580112"
-      7.90000000000000035527.to_s.should == "7.9"
-      5.93100000000000004974.to_s.should == "5.931"
-      5.21229313600000043749.to_s.should == "5.212293136"
-      503.44173809000000119340.to_s.should == "503.44173809"
-      79.26000000000000511591.to_s.should == "79.26"
-      8.51524999999999998579.to_s.should == "8.51525"
-      174.00000000000000000000.to_s.should == "174.0"
-      50.39580000000000126192.to_s.should == "50.3958"
-      35.28999999999999914735.to_s.should == "35.29"
-      5.43136675399999990788.to_s.should == "5.431366754"
-      654.07680000000004838512.to_s.should == "654.0768"
-      6.07423700000000010846.to_s.should == "6.074237"
-      102.25779799999999397642.to_s.should == "102.257798"
-      5.08129999999999970584.to_s.should == "5.0813"
-      6.00000000000000000000.to_s.should == "6.0"
-      8.30000000000000071054.to_s.should == "8.3"
-      32.68345999999999662577.to_s.should == "32.68346"
-      581.11170000000004165486.to_s.should == "581.1117"
-      76.31342999999999676675.to_s.should == "76.31343"
-      438.30826000000001840817.to_s.should == "438.30826"
-      482.06631994000002805478.to_s.should == "482.06631994"
-      55.92721026899999969828.to_s.should == "55.927210269"
-      4.00000000000000000000.to_s.should == "4.0"
-      55.86693999999999959982.to_s.should == "55.86694"
-      787.98299999999994724931.to_s.should == "787.983"
-      5.73810511000000023074.to_s.should == "5.73810511"
-      74.51926810000000500622.to_s.should == "74.5192681"
-      892.89999999999997726263.to_s.should == "892.9"
-      68.27299999999999613465.to_s.should == "68.273"
-      904.10000000000002273737.to_s.should == "904.1"
-      5.23200000000000020606.to_s.should == "5.232"
-      4.09628000000000014325.to_s.should == "4.09628"
-      46.05152633699999853434.to_s.should == "46.051526337"
-      142.12884990599999923688.to_s.should == "142.128849906"
-      3.83057023500000015659.to_s.should == "3.830570235"
-      11.81684594699999912848.to_s.should == "11.816845947"
-      80.50000000000000000000.to_s.should == "80.5"
-      382.18215010000000120272.to_s.should == "382.1821501"
-      55.38444606899999911320.to_s.should == "55.384446069"
-      5.78000000000000024869.to_s.should == "5.78"
-      2.88244999999999995666.to_s.should == "2.88245"
-      43.27709999999999723741.to_s.should == "43.2771"
-    end
-
-    it "random values from divisions" do
-      (1.0 / 7).to_s.should == "0.14285714285714285"
-
-      # 50.times do
-      #    a = rand(10)
-      #    b = rand(10)
-      #    c = rand(10)
-      #    d = rand(10)
-      #    expression = "#{a}.#{b} / #{c}.#{d}"
-      #    puts "      (#{expression}).to_s.should == #{eval(expression).to_s.inspect}"
-      #  end
-
-      (1.1 / 7.1).to_s.should == "0.15492957746478875"
-      (6.5 / 8.8).to_s.should == "0.7386363636363635"
-      (4.8 / 4.3).to_s.should == "1.1162790697674418"
-      (4.0 / 1.9).to_s.should == "2.1052631578947367"
-      (9.1 / 0.8).to_s.should == "11.374999999999998"
-      (5.3 / 7.5).to_s.should == "0.7066666666666667"
-      (2.8 / 1.8).to_s.should == "1.5555555555555554"
-      (2.1 / 2.5).to_s.should == "0.8400000000000001"
-      (3.5 / 6.0).to_s.should == "0.5833333333333334"
-      (4.6 / 0.3).to_s.should == "15.333333333333332"
-      (0.6 / 2.4).to_s.should == "0.25"
-      (1.3 / 9.1).to_s.should == "0.14285714285714288"
-      (0.3 / 5.0).to_s.should == "0.06"
-      (5.0 / 4.2).to_s.should == "1.1904761904761905"
-      (3.0 / 2.0).to_s.should == "1.5"
-      (6.3 / 2.0).to_s.should == "3.15"
-      (5.4 / 6.0).to_s.should == "0.9"
-      (9.6 / 8.1).to_s.should == "1.1851851851851851"
-      (8.7 / 1.6).to_s.should == "5.437499999999999"
-      (1.9 / 7.8).to_s.should == "0.24358974358974358"
-      (0.5 / 2.1).to_s.should == "0.23809523809523808"
-      (9.3 / 5.8).to_s.should == "1.6034482758620692"
-      (2.7 / 8.0).to_s.should == "0.3375"
-      (9.7 / 7.8).to_s.should == "1.2435897435897436"
-      (8.1 / 2.4).to_s.should == "3.375"
-      (7.7 / 2.7).to_s.should == "2.8518518518518516"
-      (7.9 / 1.7).to_s.should == "4.647058823529412"
-      (6.5 / 8.2).to_s.should == "0.7926829268292683"
-      (7.8 / 9.6).to_s.should == "0.8125"
-      (2.2 / 4.6).to_s.should == "0.47826086956521746"
-      (0.0 / 1.0).to_s.should == "0.0"
-      (8.3 / 2.9).to_s.should == "2.8620689655172415"
-      (3.1 / 6.1).to_s.should == "0.5081967213114754"
-      (2.8 / 7.8).to_s.should == "0.358974358974359"
-      (8.0 / 0.1).to_s.should == "80.0"
-      (1.7 / 6.4).to_s.should == "0.265625"
-      (1.8 / 5.4).to_s.should == "0.3333333333333333"
-      (8.0 / 5.8).to_s.should == "1.3793103448275863"
-      (5.2 / 4.1).to_s.should == "1.2682926829268295"
-      (9.8 / 5.8).to_s.should == "1.6896551724137934"
-      (5.4 / 9.5).to_s.should == "0.5684210526315789"
-      (8.4 / 4.9).to_s.should == "1.7142857142857142"
-      (1.7 / 3.5).to_s.should == "0.4857142857142857"
-      (1.2 / 5.1).to_s.should == "0.23529411764705882"
-      (1.4 / 2.0).to_s.should == "0.7"
-      (4.8 / 8.0).to_s.should == "0.6"
-      (9.0 / 2.5).to_s.should == "3.6"
-      (0.2 / 0.6).to_s.should == "0.33333333333333337"
-      (7.8 / 5.2).to_s.should == "1.5"
-      (9.5 / 5.5).to_s.should == "1.7272727272727273"
-    end
-  end
-end
-
-describe "Float#to_s" do
-  before :each do
-    @internal = Encoding.default_internal
-  end
-
-  after :each do
-    Encoding.default_internal = @internal
-  end
-
-  it "returns a String in US-ASCII encoding when Encoding.default_internal is nil" do
-    Encoding.default_internal = nil
-    1.23.to_s.encoding.should equal(Encoding::US_ASCII)
-  end
-
-  it "returns a String in US-ASCII encoding when Encoding.default_internal is not nil" do
-    Encoding.default_internal = Encoding::IBM437
-    5.47.to_s.encoding.should equal(Encoding::US_ASCII)
-  end
+  it_behaves_like :float_to_s, :to_s
 end
diff --git a/spec/ruby/core/float/truncate_spec.rb b/spec/ruby/core/float/truncate_spec.rb
index 2c80145f9f..1750e3fdbc 100644
--- a/spec/ruby/core/float/truncate_spec.rb
+++ b/spec/ruby/core/float/truncate_spec.rb
@@ -5,10 +5,10 @@ describe "Float#truncate" do
   it_behaves_like :float_to_i, :truncate
 
   it "returns self truncated to an optionally given precision" do
-    2.1679.truncate(0).should   eql(2)
-    7.1.truncate(1).should      eql(7.1)
-    214.94.truncate(-1).should  eql(210)
-    -1.234.truncate(2).should   eql(-1.23)
-    5.123812.truncate(4).should eql(5.1238)
+    2.1679.truncate(0).should.eql?(2)
+    7.1.truncate(1).should.eql?(7.1)
+    214.94.truncate(-1).should.eql?(210)
+    -1.234.truncate(2).should.eql?(-1.23)
+    5.123812.truncate(4).should.eql?(5.1238)
   end
 end
diff --git a/spec/ruby/core/float/uminus_spec.rb b/spec/ruby/core/float/uminus_spec.rb
index e676a26ada..57bae0fb4b 100644
--- a/spec/ruby/core/float/uminus_spec.rb
+++ b/spec/ruby/core/float/uminus_spec.rb
@@ -23,6 +23,6 @@ describe "Float#-@" do
   end
 
   it "returns NaN for NaN" do
-    nan_value.send(:-@).nan?.should == true
+    nan_value.send(:-@).should.nan?
   end
 end
diff --git a/spec/ruby/core/float/uplus_spec.rb b/spec/ruby/core/float/uplus_spec.rb
index 936123558c..b979b2717a 100644
--- a/spec/ruby/core/float/uplus_spec.rb
+++ b/spec/ruby/core/float/uplus_spec.rb
@@ -4,6 +4,6 @@ describe "Float#+@" do
   it "returns the same value with same sign (twos complement)" do
     34.56.send(:+@).should == 34.56
     -34.56.send(:+@).should == -34.56
-    0.0.send(:+@).should eql(0.0)
+    0.0.send(:+@).should.eql?(0.0)
   end
 end
diff --git a/spec/ruby/core/float/zero_spec.rb b/spec/ruby/core/float/zero_spec.rb
index e70edc422a..1f3de27793 100644
--- a/spec/ruby/core/float/zero_spec.rb
+++ b/spec/ruby/core/float/zero_spec.rb
@@ -2,8 +2,8 @@ require_relative '../../spec_helper'
 
 describe "Float#zero?" do
   it "returns true if self is 0.0" do
-    0.0.zero?.should == true
-    1.0.zero?.should == false
-    -1.0.zero?.should == false
+    0.0.should.zero?
+    1.0.should_not.zero?
+    -1.0.should_not.zero?
   end
 end
diff --git a/spec/ruby/core/gc/auto_compact_spec.rb b/spec/ruby/core/gc/auto_compact_spec.rb
new file mode 100644
index 0000000000..33ad1cb56c
--- /dev/null
+++ b/spec/ruby/core/gc/auto_compact_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+describe "GC.auto_compact" do
+  it "can set and get a boolean value" do
+    begin
+      GC.auto_compact = GC.auto_compact
+    rescue NotImplementedError # platform does not support autocompact
+      skip
+    end
+
+    original = GC.auto_compact
+    begin
+      GC.auto_compact = !original
+    rescue NotImplementedError # platform does not support autocompact
+      skip
+    end
+
+    begin
+      GC.auto_compact.should == !original
+    ensure
+      GC.auto_compact = original
+    end
+  end
+end
diff --git a/spec/ruby/core/gc/config_spec.rb b/spec/ruby/core/gc/config_spec.rb
new file mode 100644
index 0000000000..57160f122c
--- /dev/null
+++ b/spec/ruby/core/gc/config_spec.rb
@@ -0,0 +1,97 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "3.4" do
+  describe "GC.config" do
+    context "without arguments" do
+      it "returns a hash of current settings" do
+        GC.config.should.is_a?(Hash)
+      end
+
+      it "includes the name of currently loaded GC implementation as a global key" do
+        GC.config.should.include?(:implementation)
+        GC.config[:implementation].should.is_a?(String)
+      end
+    end
+
+    context "with a hash of options" do
+      it "allows to set GC implementation's options, returning the new config" do
+        config = GC.config({})
+        # Try to find a boolean setting to reliably test changing it.
+        key, _value = config.find { |_k, v| v == true }
+        skip unless key
+
+        GC.config(key => false).should == config.merge(key => false)
+        GC.config[key].should == false
+        GC.config(key => true).should == config
+        GC.config[key].should == true
+      ensure
+        GC.config(config.except(:implementation))
+      end
+
+      it "does not change settings that aren't present in the hash" do
+        previous = GC.config
+        GC.config({})
+        GC.config.should == previous
+      end
+
+      it "ignores unknown keys" do
+        previous = GC.config
+        GC.config(foo: "bar")
+        GC.config.should == previous
+      end
+
+      ruby_version_is ""..."4.0" do
+        it "returns the same as GC.config but without the :implementation key" do
+          previous = GC.config
+          GC.config({}).should == previous.except(:implementation)
+        end
+      end
+
+      ruby_version_is "4.0" do
+        it "returns the same as GC.config, including the :implementation key" do
+          previous = GC.config
+          GC.config({}).should == previous
+        end
+      end
+
+      it "raises an ArgumentError if options include global keys" do
+        -> { GC.config(implementation: "default") }.should.raise(ArgumentError, 'Attempting to set read-only key "Implementation"')
+      end
+    end
+
+    context "with a non-hash argument" do
+      it "returns current settings if argument is nil" do
+        GC.config(nil).should == GC.config
+      end
+
+      it "raises ArgumentError for all other arguments" do
+        -> { GC.config([]) }.should.raise(ArgumentError)
+        -> { GC.config("default") }.should.raise(ArgumentError)
+        -> { GC.config(1) }.should.raise(ArgumentError)
+      end
+    end
+
+    guard -> { PlatformGuard.standard? && GC.config[:implementation] == "default" } do
+      context "with default GC implementation on MRI" do
+        before do
+          @default_config = GC.config({})
+        end
+
+        after do
+          GC.config(@default_config.except(:implementation))
+        end
+
+        it "includes :rgengc_allow_full_mark option, true by default" do
+          GC.config.should.include?(:rgengc_allow_full_mark)
+          GC.config[:rgengc_allow_full_mark].should == true
+        end
+
+        it "allows to set :rgengc_allow_full_mark" do
+          # This key maps truthy and falsey values to true and false.
+          GC.config(rgengc_allow_full_mark: nil).should == @default_config.merge(rgengc_allow_full_mark: false)
+          GC.config(rgengc_allow_full_mark: 1.23).should == @default_config.merge(rgengc_allow_full_mark: true)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/gc/count_spec.rb b/spec/ruby/core/gc/count_spec.rb
index af2fbbe713..fe20c4ed2b 100644
--- a/spec/ruby/core/gc/count_spec.rb
+++ b/spec/ruby/core/gc/count_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "GC.count" do
   it "returns an integer" do
-    GC.count.should be_kind_of(Integer)
+    GC.count.should.is_a?(Integer)
   end
 
   it "increases as collections are run" do
diff --git a/spec/ruby/core/gc/disable_spec.rb b/spec/ruby/core/gc/disable_spec.rb
index b0221d8520..f89a9d2768 100644
--- a/spec/ruby/core/gc/disable_spec.rb
+++ b/spec/ruby/core/gc/disable_spec.rb
@@ -5,7 +5,7 @@ describe "GC.disable" do
     GC.enable
   end
 
-  it "returns true iff the garbage collection was previously disabled" do
+  it "returns true if and only if the garbage collection was previously disabled" do
     GC.enable
     GC.disable.should == false
     GC.disable.should == true
diff --git a/spec/ruby/core/gc/enable_spec.rb b/spec/ruby/core/gc/enable_spec.rb
index eb8d572f46..ca4488547a 100644
--- a/spec/ruby/core/gc/enable_spec.rb
+++ b/spec/ruby/core/gc/enable_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "GC.enable" do
 
-  it "returns true iff the garbage collection was already disabled" do
+  it "returns true if and only if the garbage collection was already disabled" do
     GC.enable
     GC.enable.should == false
     GC.disable
diff --git a/spec/ruby/core/gc/measure_total_time_spec.rb b/spec/ruby/core/gc/measure_total_time_spec.rb
new file mode 100644
index 0000000000..f5377c18fd
--- /dev/null
+++ b/spec/ruby/core/gc/measure_total_time_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+
+describe "GC.measure_total_time" do
+  before :each do
+    @default = GC.measure_total_time
+  end
+
+  after :each do
+    GC.measure_total_time = @default
+  end
+
+  it "can set and get a boolean value" do
+    original = GC.measure_total_time
+    GC.measure_total_time = !original
+    GC.measure_total_time.should == !original
+  end
+end
diff --git a/spec/ruby/core/gc/profiler/disable_spec.rb b/spec/ruby/core/gc/profiler/disable_spec.rb
index 321a207deb..74089693eb 100644
--- a/spec/ruby/core/gc/profiler/disable_spec.rb
+++ b/spec/ruby/core/gc/profiler/disable_spec.rb
@@ -11,6 +11,6 @@ describe "GC::Profiler.disable" do
 
   it "disables the profiler" do
     GC::Profiler.disable
-    GC::Profiler.enabled?.should == false
+    GC::Profiler.should_not.enabled?
   end
 end
diff --git a/spec/ruby/core/gc/profiler/enable_spec.rb b/spec/ruby/core/gc/profiler/enable_spec.rb
index 1594511675..313ca3d949 100644
--- a/spec/ruby/core/gc/profiler/enable_spec.rb
+++ b/spec/ruby/core/gc/profiler/enable_spec.rb
@@ -12,6 +12,6 @@ describe "GC::Profiler.enable" do
 
   it "enables the profiler" do
     GC::Profiler.enable
-    GC::Profiler.enabled?.should == true
+    GC::Profiler.should.enabled?
   end
 end
diff --git a/spec/ruby/core/gc/profiler/enabled_spec.rb b/spec/ruby/core/gc/profiler/enabled_spec.rb
index 23677be555..cfcd0951f0 100644
--- a/spec/ruby/core/gc/profiler/enabled_spec.rb
+++ b/spec/ruby/core/gc/profiler/enabled_spec.rb
@@ -11,11 +11,11 @@ describe "GC::Profiler.enabled?" do
 
   it "reports as enabled when enabled" do
     GC::Profiler.enable
-    GC::Profiler.enabled?.should be_true
+    GC::Profiler.enabled?.should == true
   end
 
   it "reports as disabled when disabled" do
     GC::Profiler.disable
-    GC::Profiler.enabled?.should be_false
+    GC::Profiler.enabled?.should == false
   end
 end
diff --git a/spec/ruby/core/gc/profiler/result_spec.rb b/spec/ruby/core/gc/profiler/result_spec.rb
index 2ab46a8371..e888f975dc 100644
--- a/spec/ruby/core/gc/profiler/result_spec.rb
+++ b/spec/ruby/core/gc/profiler/result_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../../spec_helper'
 
 describe "GC::Profiler.result" do
   it "returns a string" do
-    GC::Profiler.result.should be_kind_of(String)
+    GC::Profiler.result.should.is_a?(String)
   end
 end
diff --git a/spec/ruby/core/gc/profiler/total_time_spec.rb b/spec/ruby/core/gc/profiler/total_time_spec.rb
index 7709f168dd..a351e922af 100644
--- a/spec/ruby/core/gc/profiler/total_time_spec.rb
+++ b/spec/ruby/core/gc/profiler/total_time_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../../spec_helper'
 
 describe "GC::Profiler.total_time" do
   it "returns an float" do
-    GC::Profiler.total_time.should be_kind_of(Float)
+    GC::Profiler.total_time.should.is_a?(Float)
   end
 end
diff --git a/spec/ruby/core/gc/start_spec.rb b/spec/ruby/core/gc/start_spec.rb
index fb6820db14..c941058969 100644
--- a/spec/ruby/core/gc/start_spec.rb
+++ b/spec/ruby/core/gc/start_spec.rb
@@ -5,4 +5,8 @@ describe "GC.start" do
     GC.start.should == nil
     GC.start.should == nil
   end
+
+  it "accepts keyword arguments" do
+    GC.start(full_mark: true, immediate_sweep: true).should == nil
+  end
 end
diff --git a/spec/ruby/core/gc/stat_spec.rb b/spec/ruby/core/gc/stat_spec.rb
index 51bd00c7c7..6e4800b3e3 100644
--- a/spec/ruby/core/gc/stat_spec.rb
+++ b/spec/ruby/core/gc/stat_spec.rb
@@ -1,16 +1,62 @@
 require_relative '../../spec_helper'
 
 describe "GC.stat" do
-  it "supports access by key" do
-    keys = [:heap_free_slots, :total_allocated_objects, :count]
-    keys.each do |key|
-      GC.stat(key).should be_kind_of(Integer)
-    end
-  end
-
   it "returns hash of values" do
     stat = GC.stat
-    stat.should be_kind_of(Hash)
-    stat.keys.should include(:count)
+    stat.should.is_a?(Hash)
+    stat.keys.should.include?(:count)
+  end
+
+  it "updates the given hash values" do
+    hash = { count: "hello", __other__: "world" }
+    stat = GC.stat(hash)
+
+    stat.should.is_a?(Hash)
+    stat.should.equal? hash
+    stat[:count].should.is_a?(Integer)
+    stat[:__other__].should == "world"
+  end
+
+  it "the values are all Integer since rb_gc_stat() returns size_t" do
+    GC.stat.values.each { |value| value.should.is_a?(Integer) }
+  end
+
+  it "can return a single value" do
+    GC.stat(:count).should.is_a?(Integer)
+  end
+
+  it "increases count after GC is run" do
+    count = GC.stat(:count)
+    GC.start
+    GC.stat(:count).should > count
+  end
+
+  it "increases major_gc_count after GC is run" do
+    count = GC.stat(:major_gc_count)
+    GC.start
+    GC.stat(:major_gc_count).should > count
+  end
+
+  it "provides some number for count" do
+    GC.stat(:count).should.is_a?(Integer)
+    GC.stat[:count].should.is_a?(Integer)
+  end
+
+  it "provides some number for heap_free_slots" do
+    GC.stat(:heap_free_slots).should.is_a?(Integer)
+    GC.stat[:heap_free_slots].should.is_a?(Integer)
+  end
+
+  it "provides some number for total_allocated_objects" do
+    GC.stat(:total_allocated_objects).should.is_a?(Integer)
+    GC.stat[:total_allocated_objects].should.is_a?(Integer)
+  end
+
+  it "raises an error if argument is not nil, a symbol, or a hash" do
+    -> { GC.stat(7) }.should.raise(TypeError, "non-hash or symbol given")
+  end
+
+  it "raises an error if an unknown key is given" do
+    -> { GC.stat(:foo) }.should.raise(ArgumentError, "unknown key: foo")
   end
 end
diff --git a/spec/ruby/core/gc/stress_spec.rb b/spec/ruby/core/gc/stress_spec.rb
index ca62c0cb4e..227a795e7f 100644
--- a/spec/ruby/core/gc/stress_spec.rb
+++ b/spec/ruby/core/gc/stress_spec.rb
@@ -7,11 +7,11 @@ describe "GC.stress" do
   end
 
   it "returns current status of GC stress mode" do
-    GC.stress.should be_false
+    GC.stress.should == false
     GC.stress = true
-    GC.stress.should be_true
+    GC.stress.should == true
     GC.stress = false
-    GC.stress.should be_false
+    GC.stress.should == false
   end
 end
 
@@ -22,6 +22,6 @@ describe "GC.stress=" do
 
   it "sets the stress mode" do
     GC.stress = true
-    GC.stress.should be_true
+    GC.stress.should == true
   end
 end
diff --git a/spec/ruby/core/gc/total_time_spec.rb b/spec/ruby/core/gc/total_time_spec.rb
new file mode 100644
index 0000000000..f10e0ad742
--- /dev/null
+++ b/spec/ruby/core/gc/total_time_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "GC.total_time" do
+  it "returns an Integer" do
+    GC.total_time.should.is_a?(Integer)
+  end
+
+  it "increases as collections are run" do
+    time_before = GC.total_time
+    GC.start
+    GC.total_time.should >= time_before
+  end
+end
diff --git a/spec/ruby/core/hash/allocate_spec.rb b/spec/ruby/core/hash/allocate_spec.rb
index 93420de866..a92accc161 100644
--- a/spec/ruby/core/hash/allocate_spec.rb
+++ b/spec/ruby/core/hash/allocate_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Hash.allocate" do
   it "returns an instance of Hash" do
     hsh = Hash.allocate
-    hsh.should be_an_instance_of(Hash)
+    hsh.should.instance_of?(Hash)
   end
 
   it "returns a fully-formed instance of Hash" do
diff --git a/spec/ruby/core/hash/any_spec.rb b/spec/ruby/core/hash/any_spec.rb
index bd33e8cd8f..c26dfabde6 100644
--- a/spec/ruby/core/hash/any_spec.rb
+++ b/spec/ruby/core/hash/any_spec.rb
@@ -4,10 +4,10 @@ describe "Hash#any?" do
   describe 'with no block given' do
     it "checks if there are any members of a Hash" do
       empty_hash = {}
-      empty_hash.any?.should == false
+      empty_hash.should_not.any?
 
       hash_with_members = { 'key' => 'value' }
-      hash_with_members.any?.should == true
+      hash_with_members.should.any?
     end
   end
 
diff --git a/spec/ruby/core/hash/assoc_spec.rb b/spec/ruby/core/hash/assoc_spec.rb
index 64442918d1..51af51a20f 100644
--- a/spec/ruby/core/hash/assoc_spec.rb
+++ b/spec/ruby/core/hash/assoc_spec.rb
@@ -6,7 +6,7 @@ describe "Hash#assoc" do
   end
 
   it "returns an Array if the argument is == to a key of the Hash" do
-    @h.assoc(:apple).should be_an_instance_of(Array)
+    @h.assoc(:apple).should.instance_of?(Array)
   end
 
   it "returns a 2-element Array if the argument is == to a key of the Hash" do
@@ -22,11 +22,11 @@ describe "Hash#assoc" do
   end
 
   it "only returns the first matching key-value pair for identity hashes" do
-    # Avoid literal String keys in Hash#[]= due to https://bugs.ruby-lang.org/issues/12855
+    # Avoid literal String keys since string literals can be frozen and interned e.g. with --enable-frozen-string-literal
     h = {}.compare_by_identity
-    k1 = 'pear'
+    k1 = 'pear'.dup
     h[k1] = :red
-    k2 = 'pear'
+    k2 = 'pear'.dup
     h[k2] = :green
     h.size.should == 2
     h.keys.grep(/pear/).size.should == 2
@@ -40,11 +40,11 @@ describe "Hash#assoc" do
   end
 
   it "returns nil if the argument is not a key of the Hash" do
-    @h.assoc(:green).should be_nil
+    @h.assoc(:green).should == nil
   end
 
   it "returns nil if the argument is not a key of the Hash even when there is a default" do
-    Hash.new(42).merge!( foo: :bar ).assoc(42).should be_nil
-    Hash.new{|h, k| h[k] = 42}.merge!( foo: :bar ).assoc(42).should be_nil
+    Hash.new(42).merge!( foo: :bar ).assoc(42).should == nil
+    Hash.new{|h, k| h[k] = 42}.merge!( foo: :bar ).assoc(42).should == nil
   end
 end
diff --git a/spec/ruby/core/hash/clear_spec.rb b/spec/ruby/core/hash/clear_spec.rb
index e7816acbbc..beff925a63 100644
--- a/spec/ruby/core/hash/clear_spec.rb
+++ b/spec/ruby/core/hash/clear_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Hash#clear" do
   it "removes all key, value pairs" do
     h = { 1 => 2, 3 => 4 }
-    h.clear.should equal(h)
+    h.clear.should.equal?(h)
     h.should == {}
   end
 
@@ -25,8 +25,8 @@ describe "Hash#clear" do
     h.default_proc.should_not == nil
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.clear  }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.clear }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.clear  }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.clear }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/clone_spec.rb b/spec/ruby/core/hash/clone_spec.rb
index 6c96fc0c67..d135a84453 100644
--- a/spec/ruby/core/hash/clone_spec.rb
+++ b/spec/ruby/core/hash/clone_spec.rb
@@ -7,6 +7,6 @@ describe "Hash#clone" do
     clone = hash.clone
 
     clone.should == hash
-    clone.should_not equal hash
+    clone.should_not.equal? hash
   end
 end
diff --git a/spec/ruby/core/hash/compact_spec.rb b/spec/ruby/core/hash/compact_spec.rb
index ec9d4b5d79..de83dabed3 100644
--- a/spec/ruby/core/hash/compact_spec.rb
+++ b/spec/ruby/core/hash/compact_spec.rb
@@ -10,7 +10,7 @@ describe "Hash#compact" do
 
   it "returns new object that rejects pair has nil value" do
     ret = @hash.compact
-    ret.should_not equal(@hash)
+    ret.should_not.equal?(@hash)
     ret.should == @compact
   end
 
@@ -18,6 +18,28 @@ describe "Hash#compact" do
     @hash.compact
     @hash.should == @initial_pairs
   end
+
+  it "retains the default value" do
+    hash = Hash.new(1)
+    hash.compact.default.should == 1
+    hash[:a] = 1
+    hash.compact.default.should == 1
+  end
+
+  it "retains the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    hash = Hash.new(&pr)
+    hash.compact.default_proc.should == pr
+    hash[:a] = 1
+    hash.compact.default_proc.should == pr
+  end
+
+  it "retains compare_by_identity flag" do
+    hash = {}.compare_by_identity
+    hash.compact.compare_by_identity?.should == true
+    hash[:a] = 1
+    hash.compact.compare_by_identity?.should == true
+  end
 end
 
 describe "Hash#compact!" do
@@ -28,7 +50,7 @@ describe "Hash#compact!" do
   end
 
   it "returns self" do
-    @hash.compact!.should equal(@hash)
+    @hash.compact!.should.equal?(@hash)
   end
 
   it "rejects own pair has nil value" do
@@ -42,7 +64,7 @@ describe "Hash#compact!" do
     end
 
     it "returns nil" do
-      @hash.compact!.should be_nil
+      @hash.compact!.should == nil
     end
   end
 
@@ -51,8 +73,8 @@ describe "Hash#compact!" do
       @hash.freeze
     end
 
-    it "keeps pairs and raises a #{frozen_error_class}" do
-      ->{ @hash.compact! }.should raise_error(frozen_error_class)
+    it "keeps pairs and raises a FrozenError" do
+      ->{ @hash.compact! }.should.raise(FrozenError)
       @hash.should == @initial_pairs
     end
   end
diff --git a/spec/ruby/core/hash/compare_by_identity_spec.rb b/spec/ruby/core/hash/compare_by_identity_spec.rb
index 0658b4954a..1abf9d5666 100644
--- a/spec/ruby/core/hash/compare_by_identity_spec.rb
+++ b/spec/ruby/core/hash/compare_by_identity_spec.rb
@@ -11,7 +11,7 @@ describe "Hash#compare_by_identity" do
     @h[[1]] = :a
     @h[[1]].should == :a
     @h.compare_by_identity
-    @h[[1].dup].should be_nil
+    @h[[1].dup].should == nil
   end
 
   it "rehashes internally so that old keys can be looked up" do
@@ -27,21 +27,21 @@ describe "Hash#compare_by_identity" do
   it "returns self" do
     h = {}
     h[:foo] = :bar
-    h.compare_by_identity.should equal h
+    h.compare_by_identity.should.equal? h
   end
 
   it "has no effect on an already compare_by_identity hash" do
     @idh[:foo] = :bar
-    @idh.compare_by_identity.should equal @idh
-    @idh.compare_by_identity?.should == true
+    @idh.compare_by_identity.should.equal? @idh
+    @idh.should.compare_by_identity?
     @idh[:foo].should == :bar
   end
 
   it "uses the semantics of BasicObject#equal? to determine key identity" do
-    [1].should_not equal([1])
+    [1].should_not.equal?([1])
     @idh[[1]] = :c
     @idh[[1]] = :d
-    :bar.should equal(:bar)
+    :bar.should.equal?(:bar)
     @idh[:bar] = :e
     @idh[:bar] = :f
     @idh.values.should == [:c, :d, :f]
@@ -64,13 +64,13 @@ describe "Hash#compare_by_identity" do
   it "regards #dup'd objects as having different identities" do
     key = ['foo']
     @idh[key.dup] = :str
-    @idh[key].should be_nil
+    @idh[key].should == nil
   end
 
   it "regards #clone'd objects as having different identities" do
     key = ['foo']
     @idh[key.clone] = :str
-    @idh[key].should be_nil
+    @idh[key].should == nil
   end
 
   it "regards references to the same object as having the same identity" do
@@ -80,24 +80,26 @@ describe "Hash#compare_by_identity" do
     @h[o].should == :o
   end
 
-  it "raises a #{frozen_error_class} on frozen hashes" do
+  it "raises a FrozenError on frozen hashes" do
     @h = @h.freeze
-    -> { @h.compare_by_identity }.should raise_error(frozen_error_class)
+    -> { @h.compare_by_identity }.should.raise(FrozenError)
   end
 
-  # Behaviour confirmed in bug #1871
+  # Behaviour confirmed in https://bugs.ruby-lang.org/issues/1871
   it "persists over #dups" do
-    @idh['foo'] = :bar
-    @idh['foo'] = :glark
+    @idh['foo'.dup] = :bar
+    @idh['foo'.dup] = :glark
     @idh.dup.should == @idh
     @idh.dup.size.should == @idh.size
+    @idh.dup.should.compare_by_identity?
   end
 
   it "persists over #clones" do
-    @idh['foo'] = :bar
-    @idh['foo'] = :glark
+    @idh['foo'.dup] = :bar
+    @idh['foo'.dup] = :glark
     @idh.clone.should == @idh
     @idh.clone.size.should == @idh.size
+    @idh.dup.should.compare_by_identity?
   end
 
   it "does not copy string keys" do
@@ -105,12 +107,19 @@ describe "Hash#compare_by_identity" do
     @idh[foo] = true
     @idh[foo] = true
     @idh.size.should == 1
-    @idh.keys.first.should equal foo
+    @idh.keys.first.should.equal? foo
   end
 
+  # Check `#[]=` call with a String literal.
+  # Don't use `#+` because with `#+` it's no longer a String literal.
+  #
+  # See https://bugs.ruby-lang.org/issues/12855
   it "gives different identity for string literals" do
+    eval <<~RUBY
+    # frozen_string_literal: false
     @idh['foo'] = 1
     @idh['foo'] = 2
+    RUBY
     @idh.values.should == [1, 2]
     @idh.size.should == 2
   end
@@ -119,20 +128,20 @@ end
 describe "Hash#compare_by_identity?" do
   it "returns false by default" do
     h = {}
-    h.compare_by_identity?.should be_false
+    h.compare_by_identity?.should == false
   end
 
   it "returns true once #compare_by_identity has been invoked on self" do
     h = {}
     h.compare_by_identity
-    h.compare_by_identity?.should be_true
+    h.compare_by_identity?.should == true
   end
 
   it "returns true when called multiple times on the same ident hash" do
     h = {}
     h.compare_by_identity
-    h.compare_by_identity?.should be_true
-    h.compare_by_identity?.should be_true
-    h.compare_by_identity?.should be_true
+    h.compare_by_identity?.should == true
+    h.compare_by_identity?.should == true
+    h.compare_by_identity?.should == true
   end
 end
diff --git a/spec/ruby/core/hash/constructor_spec.rb b/spec/ruby/core/hash/constructor_spec.rb
index ad67274802..c16f373160 100644
--- a/spec/ruby/core/hash/constructor_spec.rb
+++ b/spec/ruby/core/hash/constructor_spec.rb
@@ -42,38 +42,25 @@ describe "Hash.[]" do
     Hash[ary].should == { a: :b }
   end
 
-  ruby_version_is "" ... "2.7" do
-    it "ignores elements that are not arrays" do
-      -> {
-        Hash[[:a]].should == {}
-      }.should complain(/ignoring wrong elements/)
-      -> {
-        Hash[[:nil]].should == {}
-      }.should complain(/ignoring wrong elements/)
-    end
-  end
-
-  ruby_version_is "2.7" do
-    it "raises for elements that are not arrays" do
-      -> {
-        Hash[[:a]].should == {}
-      }.should raise_error(ArgumentError)
-      -> {
-        Hash[[:nil]].should == {}
-      }.should raise_error(ArgumentError)
-    end
+  it "raises for elements that are not arrays" do
+    -> {
+      Hash[[:a]]
+    }.should.raise(ArgumentError, "wrong element type Symbol at 0 (expected array)")
+    -> {
+      Hash[[nil]]
+    }.should.raise(ArgumentError, "wrong element type nil at 0 (expected array)")
   end
 
   it "raises an ArgumentError for arrays of more than 2 elements" do
-    ->{ Hash[[[:a, :b, :c]]].should == {} }.should raise_error(ArgumentError)
+    ->{
+      Hash[[[:a, :b, :c]]]
+    }.should.raise(ArgumentError, "invalid number of elements (3 for 1..2)")
   end
 
   it "raises an ArgumentError when passed a list of value-invalid-pairs in an array" do
     -> {
-      -> {
-        Hash[[[:a, 1], [:b], 42, [:d, 2], [:e, 2, 3], []]]
-      }.should complain(/ignoring wrong elements/)
-    }.should raise_error(ArgumentError)
+      Hash[[[:a, 1], [:b], 42, [:d, 2], [:e, 2, 3], []]]
+    }.should.raise(ArgumentError, "wrong element type Integer at 2 (expected array)")
   end
 
   describe "passed a single argument which responds to #to_hash" do
@@ -84,13 +71,13 @@ describe "Hash.[]" do
 
       result = Hash[to_hash]
       result.should == h
-      result.should_not equal(h)
+      result.should_not.equal?(h)
     end
   end
 
   it "raises an ArgumentError when passed an odd number of arguments" do
-    -> { Hash[1, 2, 3] }.should raise_error(ArgumentError)
-    -> { Hash[1, 2, { 3 => 4 }] }.should raise_error(ArgumentError)
+    -> { Hash[1, 2, 3] }.should.raise(ArgumentError)
+    -> { Hash[1, 2, { 3 => 4 }] }.should.raise(ArgumentError)
   end
 
   it "calls to_hash" do
@@ -100,24 +87,41 @@ describe "Hash.[]" do
   end
 
   it "returns an instance of a subclass when passed an Array" do
-    HashSpecs::MyHash[1,2,3,4].should be_an_instance_of(HashSpecs::MyHash)
+    HashSpecs::MyHash[1,2,3,4].should.instance_of?(HashSpecs::MyHash)
   end
 
   it "returns instances of subclasses" do
-    HashSpecs::MyHash[].should be_an_instance_of(HashSpecs::MyHash)
+    HashSpecs::MyHash[].should.instance_of?(HashSpecs::MyHash)
   end
 
   it "returns an instance of the class it's called on" do
     Hash[HashSpecs::MyHash[1, 2]].class.should == Hash
-    HashSpecs::MyHash[Hash[1, 2]].should be_an_instance_of(HashSpecs::MyHash)
+    HashSpecs::MyHash[Hash[1, 2]].should.instance_of?(HashSpecs::MyHash)
   end
 
   it "does not call #initialize on the subclass instance" do
-    HashSpecs::MyInitializerHash[Hash[1, 2]].should be_an_instance_of(HashSpecs::MyInitializerHash)
+    HashSpecs::MyInitializerHash[Hash[1, 2]].should.instance_of?(HashSpecs::MyInitializerHash)
   end
 
-  it "removes the default_proc" do
+  it "does not retain the default value" do
+    hash = Hash.new(1)
+    Hash[hash].default.should == nil
+    hash[:a] = 1
+    Hash[hash].default.should == nil
+  end
+
+  it "does not retain the default_proc" do
     hash = Hash.new { |h, k| h[k] = [] }
-    Hash[hash].default_proc.should be_nil
+    Hash[hash].default_proc.should == nil
+    hash[:a] = 1
+    Hash[hash].default_proc.should == nil
+  end
+
+  it "does not retain compare_by_identity flag" do
+    hash = { a: 1 }.compare_by_identity
+    Hash[hash].compare_by_identity?.should == false
+
+    hash = {}.compare_by_identity
+    Hash[hash].compare_by_identity?.should == false
   end
 end
diff --git a/spec/ruby/core/hash/deconstruct_keys_spec.rb b/spec/ruby/core/hash/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..f6ff3a2818
--- /dev/null
+++ b/spec/ruby/core/hash/deconstruct_keys_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../spec_helper'
+
+describe "Hash#deconstruct_keys" do
+  it "returns self" do
+    hash = {a: 1, b: 2}
+
+    hash.deconstruct_keys([:a, :b]).should.equal? hash
+  end
+
+  it "requires one argument" do
+    -> {
+      {a: 1}.deconstruct_keys
+    }.should.raise(ArgumentError, /wrong number of arguments \(given 0, expected 1\)/)
+  end
+
+  it "ignores argument" do
+    hash = {a: 1, b: 2}
+
+    hash.deconstruct_keys([:a]).should == {a: 1, b: 2}
+    hash.deconstruct_keys(0   ).should == {a: 1, b: 2}
+    hash.deconstruct_keys(''  ).should == {a: 1, b: 2}
+  end
+end
diff --git a/spec/ruby/core/hash/default_proc_spec.rb b/spec/ruby/core/hash/default_proc_spec.rb
index 83ad98e5b6..4830e02acd 100644
--- a/spec/ruby/core/hash/default_proc_spec.rb
+++ b/spec/ruby/core/hash/default_proc_spec.rb
@@ -25,24 +25,24 @@ describe "Hash#default_proc=" do
     h = Hash.new { 'Paris' }
     obj = mock('to_proc')
     obj.should_receive(:to_proc).and_return(Proc.new { 'Montreal' })
-    (h.default_proc = obj).should equal(obj)
+    (h.default_proc = obj).should.equal?(obj)
     h[:cool_city].should == 'Montreal'
   end
 
   it "overrides the static default" do
     h = Hash.new(42)
     h.default_proc = Proc.new { 6 }
-    h.default.should be_nil
+    h.default.should == nil
     h.default_proc.call.should == 6
   end
 
   it "raises an error if passed stuff not convertible to procs" do
-    ->{{}.default_proc = 42}.should raise_error(TypeError)
+    ->{{}.default_proc = 42}.should.raise(TypeError)
   end
 
   it "returns the passed Proc" do
     new_proc = Proc.new {}
-    ({}.default_proc = new_proc).should equal(new_proc)
+    ({}.default_proc = new_proc).should.equal?(new_proc)
   end
 
   it "clears the default proc if passed nil" do
@@ -53,28 +53,28 @@ describe "Hash#default_proc=" do
   end
 
   it "returns nil if passed nil" do
-    ({}.default_proc = nil).should be_nil
+    ({}.default_proc = nil).should == nil
   end
 
   it "accepts a lambda with an arity of 2" do
     h = {}
     -> do
       h.default_proc = -> a, b { }
-    end.should_not raise_error(TypeError)
+    end.should_not.raise(TypeError)
   end
 
   it "raises a TypeError if passed a lambda with an arity other than 2" do
     h = {}
     -> do
       h.default_proc = -> a { }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
     -> do
       h.default_proc = -> a, b, c { }
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { {}.freeze.default_proc = Proc.new {} }.should raise_error(frozen_error_class)
-    -> { {}.freeze.default_proc = nil }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { {}.freeze.default_proc = Proc.new {} }.should.raise(FrozenError)
+    -> { {}.freeze.default_proc = nil }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/default_spec.rb b/spec/ruby/core/hash/default_spec.rb
index 6cad65bb62..17ee032e2b 100644
--- a/spec/ruby/core/hash/default_spec.rb
+++ b/spec/ruby/core/hash/default_spec.rb
@@ -39,8 +39,8 @@ describe "Hash#default=" do
     end
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.default = nil }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.default = nil }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.default = nil }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.default = nil }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/delete_if_spec.rb b/spec/ruby/core/hash/delete_if_spec.rb
index 345a24a726..3090633d88 100644
--- a/spec/ruby/core/hash/delete_if_spec.rb
+++ b/spec/ruby/core/hash/delete_if_spec.rb
@@ -12,13 +12,13 @@ describe "Hash#delete_if" do
 
   it "removes every entry for which block is true and returns self" do
     h = { a: 1, b: 2, c: 3, d: 4 }
-    h.delete_if { |k,v| v % 2 == 1 }.should equal(h)
+    h.delete_if { |k,v| v % 2 == 1 }.should.equal?(h)
     h.should == { b: 2, d: 4 }
   end
 
   it "removes all entries if the block is true" do
     h = { a: 1, b: 2, c: 3 }
-    h.delete_if { |k,v| true }.should equal(h)
+    h.delete_if { |k,v| true }.should.equal?(h)
     h.should == {}
   end
 
@@ -34,9 +34,9 @@ describe "Hash#delete_if" do
     each_pairs.should == delete_pairs
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.delete_if { false } }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.delete_if { true } }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.delete_if { false } }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.delete_if { true } }.should.raise(FrozenError)
   end
 
   it_behaves_like :hash_iteration_no_block, :delete_if
diff --git a/spec/ruby/core/hash/delete_spec.rb b/spec/ruby/core/hash/delete_spec.rb
index a69815c1d9..33ff01bf36 100644
--- a/spec/ruby/core/hash/delete_spec.rb
+++ b/spec/ruby/core/hash/delete_spec.rb
@@ -24,7 +24,7 @@ describe "Hash#delete" do
   it "allows removing a key while iterating" do
     h = { a: 1, b: 2 }
     visited = []
-    h.each_pair { |k,v|
+    h.each_pair { |k, v|
       visited << k
       h.delete(k)
     }
@@ -32,13 +32,27 @@ describe "Hash#delete" do
     h.should == {}
   end
 
+  it "allows removing a key while iterating for big hashes" do
+    h = { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9, j: 10,
+          k: 11, l: 12, m: 13, n: 14, o: 15, p: 16, q: 17, r: 18, s: 19, t: 20,
+          u: 21, v: 22, w: 23, x: 24, y: 25, z: 26 }
+    visited = []
+    h.each_pair { |k, v|
+      visited << k
+      h.delete(k)
+    }
+    visited.should == [:a, :b, :c, :d, :e, :f, :g, :h, :i, :j, :k, :l, :m,
+                       :n, :o, :p, :q, :r, :s, :t, :u, :v, :w, :x, :y, :z]
+    h.should == {}
+  end
+
   it "accepts keys with private #hash method" do
     key = HashSpecs::KeyWithPrivateHash.new
     { key => 5 }.delete(key).should == 5
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.delete("foo")  }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.delete("foo") }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.delete("foo") }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.delete("foo") }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/dig_spec.rb b/spec/ruby/core/hash/dig_spec.rb
index aa0ecadd2f..94ac94e850 100644
--- a/spec/ruby/core/hash/dig_spec.rb
+++ b/spec/ruby/core/hash/dig_spec.rb
@@ -5,16 +5,16 @@ describe "Hash#dig" do
   it "returns #[] with one arg" do
     h = { 0 => false, a: 1 }
     h.dig(:a).should == 1
-    h.dig(0).should be_false
-    h.dig(1).should be_nil
+    h.dig(0).should == false
+    h.dig(1).should == nil
   end
 
   it "returns the nested value specified by the sequence of keys" do
     h = { foo: { bar: { baz: 1 } } }
     h.dig(:foo, :bar, :baz).should == 1
-    h.dig(:foo, :bar, :nope).should be_nil
-    h.dig(:foo, :baz).should be_nil
-    h.dig(:bar, :baz, :foo).should be_nil
+    h.dig(:foo, :bar, :nope).should == nil
+    h.dig(:foo, :baz).should == nil
+    h.dig(:bar, :baz, :foo).should == nil
   end
 
   it "returns the nested value specified if the sequence includes an index" do
@@ -28,7 +28,7 @@ describe "Hash#dig" do
   end
 
   it "raises an ArgumentError if no arguments provided" do
-    -> { { the: 'borg' }.dig() }.should raise_error(ArgumentError)
+    -> { { the: 'borg' }.dig() }.should.raise(ArgumentError)
   end
 
   it "handles type-mixed deep digging" do
@@ -47,8 +47,8 @@ describe "Hash#dig" do
   it "raises TypeError if an intermediate element does not respond to #dig" do
     h = {}
     h[:foo] = [ { bar: [ 1 ] }, [ nil, 'str' ] ]
-    -> { h.dig(:foo, 0, :bar, 0, 0) }.should raise_error(TypeError)
-    -> { h.dig(:foo, 1, 1, 0) }.should raise_error(TypeError)
+    -> { h.dig(:foo, 0, :bar, 0, 0) }.should.raise(TypeError)
+    -> { h.dig(:foo, 1, 1, 0) }.should.raise(TypeError)
   end
 
   it "calls #dig on the result of #[] with the remaining arguments" do
@@ -60,7 +60,7 @@ describe "Hash#dig" do
   it "respects Hash's default" do
     default = {bar: 42}
     h = Hash.new(default)
-    h.dig(:foo).should equal default
+    h.dig(:foo).should.equal? default
     h.dig(:foo, :bar).should == 42
   end
 end
diff --git a/spec/ruby/core/hash/each_key_spec.rb b/spec/ruby/core/hash/each_key_spec.rb
index c84dd696d5..5b2e9deb63 100644
--- a/spec/ruby/core/hash/each_key_spec.rb
+++ b/spec/ruby/core/hash/each_key_spec.rb
@@ -7,7 +7,7 @@ describe "Hash#each_key" do
   it "calls block once for each key, passing key" do
     r = {}
     h = { 1 => -1, 2 => -2, 3 => -3, 4 => -4 }
-    h.each_key { |k| r[k] = k }.should equal(h)
+    h.each_key { |k| r[k] = k }.should.equal?(h)
     r.should == { 1 => 1, 2 => 2, 3 => 3, 4 => 4 }
   end
 
diff --git a/spec/ruby/core/hash/each_pair_spec.rb b/spec/ruby/core/hash/each_pair_spec.rb
index eb6656681d..01810c130c 100644
--- a/spec/ruby/core/hash/each_pair_spec.rb
+++ b/spec/ruby/core/hash/each_pair_spec.rb
@@ -1,11 +1,111 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
 require_relative 'shared/iteration'
-require_relative 'shared/each'
 require_relative '../enumerable/shared/enumeratorized'
 
 describe "Hash#each_pair" do
-  it_behaves_like :hash_each, :each_pair
   it_behaves_like :hash_iteration_no_block, :each_pair
   it_behaves_like :enumeratorized_with_origin_size, :each_pair, { 1 => 2, 3 => 4, 5 => 6 }
+
+  # This is inconsistent with below, MRI checks the block arity in rb_hash_each_pair()
+  it "yields a [[key, value]] Array for each pair to a block expecting |*args|" do
+    all_args = []
+    { 1 => 2, 3 => 4 }.each_pair { |*args| all_args << args }
+    all_args.sort.should == [[[1, 2]], [[3, 4]]]
+  end
+
+  it "yields the key and value of each pair to a block expecting |key, value|" do
+    r = {}
+    h = { a: 1, b: 2, c: 3, d: 5 }
+    h.each_pair { |k,v| r[k.to_s] = v.to_s }.should.equal?(h)
+    r.should == { "a" => "1", "b" => "2", "c" => "3", "d" => "5" }
+  end
+
+  it "yields the key only to a block expecting |key,|" do
+    ary = []
+    h = { "a" => 1, "b" => 2, "c" => 3 }
+    h.each_pair { |k,| ary << k }
+    ary.sort.should == ["a", "b", "c"]
+  end
+
+  it "always yields an Array of 2 elements, even when given a callable of arity 2" do
+    obj = Object.new
+    def obj.foo(key, value)
+    end
+
+    -> {
+      { "a" => 1 }.each_pair(&obj.method(:foo))
+    }.should.raise(ArgumentError)
+
+    -> {
+      { "a" => 1 }.each_pair(&-> key, value { })
+    }.should.raise(ArgumentError)
+  end
+
+  it "yields an Array of 2 elements when given a callable of arity 1" do
+    obj = Object.new
+    def obj.foo(key_value)
+      ScratchPad << key_value
+    end
+
+    ScratchPad.record([])
+    { "a" => 1 }.each_pair(&obj.method(:foo))
+    ScratchPad.recorded.should == [["a", 1]]
+  end
+
+  it "raises an error for a Hash when an arity enforcing callable of arity >2 is passed in" do
+    obj = Object.new
+    def obj.foo(key, value, extra)
+    end
+
+    -> {
+      { "a" => 1 }.each_pair(&obj.method(:foo))
+    }.should.raise(ArgumentError)
+  end
+
+  it "uses the same order as keys() and values()" do
+    h = { a: 1, b: 2, c: 3, d: 5 }
+    keys = []
+    values = []
+
+    h.each_pair do |k, v|
+      keys << k
+      values << v
+    end
+
+    keys.should == h.keys
+    values.should == h.values
+  end
+
+  # Confirming the argument-splatting works from child class for both k, v and [k, v]
+  it "properly expands (or not) child class's 'each'-yielded args" do
+    cls1 = Class.new(Hash) do
+      attr_accessor :k_v
+      def each
+        super do |k, v|
+          @k_v = [k, v]
+          yield k, v
+        end
+      end
+    end
+
+    cls2 = Class.new(Hash) do
+      attr_accessor :k_v
+      def each
+        super do |k, v|
+          @k_v = [k, v]
+          yield([k, v])
+        end
+      end
+    end
+
+    obj1 = cls1.new
+    obj1['a'] = 'b'
+    obj1.map {|k, v| [k, v]}.should == [['a', 'b']]
+    obj1.k_v.should == ['a', 'b']
+
+    obj2 = cls2.new
+    obj2['a'] = 'b'
+    obj2.map {|k, v| [k, v]}.should == [['a', 'b']]
+    obj2.k_v.should == ['a', 'b']
+  end
 end
diff --git a/spec/ruby/core/hash/each_spec.rb b/spec/ruby/core/hash/each_spec.rb
index f0de0bdee5..1644b63216 100644
--- a/spec/ruby/core/hash/each_spec.rb
+++ b/spec/ruby/core/hash/each_spec.rb
@@ -1,11 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/iteration'
-require_relative 'shared/each'
-require_relative '../enumerable/shared/enumeratorized'
 
 describe "Hash#each" do
-  it_behaves_like :hash_each, :each
-  it_behaves_like :hash_iteration_no_block, :each
-  it_behaves_like :enumeratorized_with_origin_size, :each, { 1 => 2, 3 => 4, 5 => 6 }
+  it "is an alias of Hash#each_pair" do
+    Hash.instance_method(:each).should == Hash.instance_method(:each_pair)
+  end
 end
diff --git a/spec/ruby/core/hash/each_value_spec.rb b/spec/ruby/core/hash/each_value_spec.rb
index 19b076730d..2df95a8789 100644
--- a/spec/ruby/core/hash/each_value_spec.rb
+++ b/spec/ruby/core/hash/each_value_spec.rb
@@ -7,7 +7,7 @@ describe "Hash#each_value" do
   it "calls block once for each key, passing value" do
     r = []
     h = { a: -5, b: -3, c: -2, d: -1, e: -1 }
-    h.each_value { |v| r << v }.should equal(h)
+    h.each_value { |v| r << v }.should.equal?(h)
     r.sort.should == [-5, -3, -2, -1, -1]
   end
 
diff --git a/spec/ruby/core/hash/element_reference_spec.rb b/spec/ruby/core/hash/element_reference_spec.rb
index 2eb65d3789..3d074b346d 100644
--- a/spec/ruby/core/hash/element_reference_spec.rb
+++ b/spec/ruby/core/hash/element_reference_spec.rb
@@ -12,7 +12,7 @@ describe "Hash#[]" do
     h[[]].should == "baz"
   end
 
-  it "returns nil as default default value" do
+  it "returns nil as default value" do
     { 0 => 0 }[5].should == nil
   end
 
@@ -30,13 +30,13 @@ describe "Hash#[]" do
   end
 
   it "does not create copies of the immediate default value" do
-    str = "foo"
+    str = +"foo"
     h = Hash.new(str)
     a = h[:a]
     b = h[:b]
     a << "bar"
 
-    a.should equal(b)
+    a.should.equal?(b)
     a.should == "foobar"
     b.should == "foobar"
   end
@@ -117,4 +117,18 @@ describe "Hash#[]" do
     key = HashSpecs::KeyWithPrivateHash.new
     { key => 42 }[key].should == 42
   end
+
+  it "does not dispatch to hash for Boolean, Integer, Float, String, or Symbol" do
+    code = <<-EOC
+      load '#{fixture __FILE__, "name.rb"}'
+      hash = { true => 42, false => 42, 1 => 42, 2.0 => 42, "hello" => 42, :ok => 42 }
+      [true, false, 1, 2.0, "hello", :ok].each do |value|
+        raise "incorrect value" unless hash[value] == 42
+      end
+      puts "Ok."
+    EOC
+    result = ruby_exe(code, args: "2>&1")
+    result.should == "Ok.\n"
+  end
+
 end
diff --git a/spec/ruby/core/hash/element_set_spec.rb b/spec/ruby/core/hash/element_set_spec.rb
index 67c5a04d73..bb805477ca 100644
--- a/spec/ruby/core/hash/element_set_spec.rb
+++ b/spec/ruby/core/hash/element_set_spec.rb
@@ -1,7 +1,121 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/store'
 
 describe "Hash#[]=" do
-  it_behaves_like :hash_store, :[]=
+  it "associates the key with the value" do
+    h = { a: 1 }
+    h[:b] = 2
+    h.should == { b:2, a:1 }
+  end
+
+  it "returns the assigned value" do
+    h = {}
+    h.send(:[]=, 1, 2).should == 2
+  end
+
+  it "duplicates string keys using dup semantics" do
+    # dup doesn't copy singleton methods
+    key = +"foo"
+    def key.reverse() "bar" end
+    h = {}
+    h[key] = 0
+    h.keys[0].reverse.should == "oof"
+  end
+
+  it "stores unequal keys that hash to the same value" do
+    h = {}
+    k1 = ["x"]
+    k2 = ["y"]
+    # So they end up in the same bucket
+    k1.should_receive(:hash).and_return(0)
+    k2.should_receive(:hash).and_return(0)
+
+    h[k1] = 1
+    h[k2] = 2
+    h.size.should == 2
+  end
+
+  it "accepts keys with private #hash method" do
+    key = HashSpecs::KeyWithPrivateHash.new
+    h = {}
+    h[key] = "foo"
+    h[key].should == "foo"
+  end
+
+  it " accepts keys with an Integer hash" do
+    o = mock(hash: 1 << 100)
+    h = {}
+    h[o] = 1
+    h[o].should == 1
+  end
+
+  it "duplicates and freezes string keys" do
+    key = +"foo"
+    h = {}
+    h[key] = 0
+    key << "bar"
+
+    h.should == { "foo" => 0 }
+    h.keys[0].should.frozen?
+  end
+
+  it "doesn't duplicate and freeze already frozen string keys" do
+    key = "foo".freeze
+    h = {}
+    h[key] = 0
+    h.keys[0].should.equal?(key)
+  end
+
+  it "keeps the existing key in the hash if there is a matching one" do
+    h = { "a" => 1, "b" => 2, "c" => 3, "d" => 4 }
+    key1 = HashSpecs::ByValueKey.new(13)
+    key2 = HashSpecs::ByValueKey.new(13)
+    h[key1] = 41
+    key_in_hash = h.keys.last
+    key_in_hash.should.equal?(key1)
+    h[key2] = 42
+    last_key = h.keys.last
+    last_key.should.equal?(key_in_hash)
+    last_key.should_not.equal?(key2)
+  end
+
+  it "keeps the existing String key in the hash if there is a matching one" do
+    h = { "a" => 1, "b" => 2, "c" => 3, "d" => 4 }
+    key1 = "foo".dup
+    key2 = "foo".dup
+    key1.should_not.equal?(key2)
+    h[key1] = 41
+    frozen_key = h.keys.last
+    frozen_key.should_not.equal?(key1)
+    h[key2] = 42
+    h.keys.last.should.equal?(frozen_key)
+    h.keys.last.should_not.equal?(key2)
+  end
+
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash[1] = 2 }.should.raise(FrozenError)
+  end
+
+  it "does not raise an exception if changing the value of an existing key during iteration" do
+    hash = {1 => 2, 3 => 4, 5 => 6}
+    hash.each { hash[1] = :foo }
+    hash.should == {1 => :foo, 3 => 4, 5 => 6}
+  end
+
+  it "does not dispatch to hash for Boolean, Integer, Float, String, or Symbol" do
+    code = <<-EOC
+      load '#{fixture __FILE__, "name.rb"}'
+      hash = {}
+      [true, false, 1, 2.0, "hello", :ok].each do |value|
+        hash[value] = 42
+        raise "incorrect value" unless hash[value] == 42
+        hash[value] = 43
+        raise "incorrect value" unless hash[value] == 43
+      end
+      puts "OK"
+      puts hash.size
+    EOC
+    result = ruby_exe(code, args: "2>&1")
+    result.should == "OK\n6\n"
+  end
 end
diff --git a/spec/ruby/core/hash/empty_spec.rb b/spec/ruby/core/hash/empty_spec.rb
index e9be44bab0..881e1cc34b 100644
--- a/spec/ruby/core/hash/empty_spec.rb
+++ b/spec/ruby/core/hash/empty_spec.rb
@@ -3,13 +3,13 @@ require_relative 'fixtures/classes'
 
 describe "Hash#empty?" do
   it "returns true if the hash has no entries" do
-    {}.empty?.should == true
-    { 1 => 1 }.empty?.should == false
+    {}.should.empty?
+    { 1 => 1 }.should_not.empty?
   end
 
   it "returns true if the hash has no entries and has a default value" do
-    Hash.new(5).empty?.should == true
-    Hash.new { 5 }.empty?.should == true
-    Hash.new { |hsh, k| hsh[k] = k }.empty?.should == true
+    Hash.new(5).should.empty?
+    Hash.new { 5 }.should.empty?
+    Hash.new { |hsh, k| hsh[k] = k }.should.empty?
   end
 end
diff --git a/spec/ruby/core/hash/equal_value_spec.rb b/spec/ruby/core/hash/equal_value_spec.rb
index ae13a42679..ab14f81489 100644
--- a/spec/ruby/core/hash/equal_value_spec.rb
+++ b/spec/ruby/core/hash/equal_value_spec.rb
@@ -13,6 +13,6 @@ describe "Hash#==" do
 
     l_val.should_receive(:==).with(r_val).and_return(true)
 
-    ({ 1 => l_val } == { 1 => r_val }).should be_true
+    ({ 1 => l_val } == { 1 => r_val }).should == true
   end
 end
diff --git a/spec/ruby/core/hash/except_spec.rb b/spec/ruby/core/hash/except_spec.rb
new file mode 100644
index 0000000000..77a020e9b7
--- /dev/null
+++ b/spec/ruby/core/hash/except_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+
+describe "Hash#except" do
+  before :each do
+    @hash = { a: 1, b: 2, c: 3 }
+  end
+
+  it "returns a new duplicate hash without arguments" do
+    ret = @hash.except
+    ret.should_not.equal?(@hash)
+    ret.should == @hash
+  end
+
+  it "returns a hash without the requested subset" do
+    @hash.except(:c, :a).should == { b: 2 }
+  end
+
+  it "ignores keys not present in the original hash" do
+    @hash.except(:a, :chunky_bacon).should == { b: 2, c: 3 }
+  end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.except(:a).default.should == nil
+    h[:a] = 1
+    h.except(:a).default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.except(:a).default_proc.should == nil
+    h[:a] = 1
+    h.except(:a).default_proc.should == nil
+  end
+
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.except(:a)
+    h2.compare_by_identity?.should == true
+  end
+end
diff --git a/spec/ruby/core/hash/fetch_spec.rb b/spec/ruby/core/hash/fetch_spec.rb
index 753167f709..f9b80b6c49 100644
--- a/spec/ruby/core/hash/fetch_spec.rb
+++ b/spec/ruby/core/hash/fetch_spec.rb
@@ -4,7 +4,7 @@ require_relative '../../shared/hash/key_error'
 
 describe "Hash#fetch" do
   context "when the key is not found" do
-    it_behaves_like :key_error, -> obj, key { obj.fetch(key) }, Hash.new(a: 5)
+    it_behaves_like :key_error, -> obj, key { obj.fetch(key) }, Hash.new({ a: 5 })
     it_behaves_like :key_error, -> obj, key { obj.fetch(key) }, {}
     it_behaves_like :key_error, -> obj, key { obj.fetch(key) }, Hash.new { 5 }
     it_behaves_like :key_error, -> obj, key { obj.fetch(key) }, Hash.new(5)
@@ -12,7 +12,7 @@ describe "Hash#fetch" do
     it "formats the object with #inspect in the KeyError message" do
       -> {
         {}.fetch('foo')
-      }.should raise_error(KeyError, 'key not found: "foo"')
+      }.should.raise(KeyError, 'key not found: "foo"')
     end
   end
 
@@ -38,7 +38,7 @@ describe "Hash#fetch" do
   end
 
   it "raises an ArgumentError when not passed one or two arguments" do
-    -> { {}.fetch()        }.should raise_error(ArgumentError)
-    -> { {}.fetch(1, 2, 3) }.should raise_error(ArgumentError)
+    -> { {}.fetch()        }.should.raise(ArgumentError)
+    -> { {}.fetch(1, 2, 3) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/hash/fetch_values_spec.rb b/spec/ruby/core/hash/fetch_values_spec.rb
index af3673f6ef..0cd48565af 100644
--- a/spec/ruby/core/hash/fetch_values_spec.rb
+++ b/spec/ruby/core/hash/fetch_values_spec.rb
@@ -19,7 +19,7 @@ describe "Hash#fetch_values" do
   end
 
   describe "with unmatched keys" do
-    it_behaves_like :key_error, -> obj, key { obj.fetch_values(key) }, Hash.new(a: 5)
+    it_behaves_like :key_error, -> obj, key { obj.fetch_values(key) }, Hash.new({ a: 5 })
 
     it "returns the default value from block" do
       @hash.fetch_values(:z) { |key| "`#{key}' is not found" }.should == ["`z' is not found"]
diff --git a/spec/ruby/core/hash/filter_spec.rb b/spec/ruby/core/hash/filter_spec.rb
index 4382c94e62..625a7feb90 100644
--- a/spec/ruby/core/hash/filter_spec.rb
+++ b/spec/ruby/core/hash/filter_spec.rb
@@ -1,12 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Hash#filter" do
-    it_behaves_like :hash_select, :filter
+describe "Hash#filter" do
+  it "is an alias of Hash#select" do
+    Hash.instance_method(:filter).should == Hash.instance_method(:select)
   end
+end
 
-  describe "Hash#filter!" do
-    it_behaves_like :hash_select!, :filter!
+describe "Hash#filter!" do
+  it "is an alias of Hash#select!" do
+    Hash.instance_method(:filter!).should == Hash.instance_method(:select!)
   end
 end
diff --git a/spec/ruby/core/hash/fixtures/name.rb b/spec/ruby/core/hash/fixtures/name.rb
new file mode 100644
index 0000000000..b203bf6ae4
--- /dev/null
+++ b/spec/ruby/core/hash/fixtures/name.rb
@@ -0,0 +1,30 @@
+class TrueClass
+  def hash
+    raise "TrueClass#hash should not be called"
+  end
+end
+class FalseClass
+  def hash
+    raise "FalseClass#hash should not be called"
+  end
+end
+class Integer
+  def hash
+    raise "Integer#hash should not be called"
+  end
+end
+class Float
+  def hash
+    raise "Float#hash should not be called"
+  end
+end
+class String
+  def hash
+    raise "String#hash should not be called"
+  end
+end
+class Symbol
+  def hash
+    raise "Symbol#hash should not be called"
+  end
+end
diff --git a/spec/ruby/core/hash/flatten_spec.rb b/spec/ruby/core/hash/flatten_spec.rb
index 825da15bfc..18e9a7b56a 100644
--- a/spec/ruby/core/hash/flatten_spec.rb
+++ b/spec/ruby/core/hash/flatten_spec.rb
@@ -9,7 +9,7 @@ describe "Hash#flatten" do
   end
 
   it "returns an Array" do
-    {}.flatten.should be_an_instance_of(Array)
+    {}.flatten.should.instance_of?(Array)
   end
 
   it "returns an empty Array for an empty Hash" do
@@ -57,6 +57,6 @@ describe "Hash#flatten" do
   it "raises a TypeError if given a non-Integer argument" do
     -> do
       @h.flatten(Object.new)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/hash/gt_spec.rb b/spec/ruby/core/hash/gt_spec.rb
index cd541d4d83..69d23b7d29 100644
--- a/spec/ruby/core/hash/gt_spec.rb
+++ b/spec/ruby/core/hash/gt_spec.rb
@@ -8,7 +8,7 @@ describe "Hash#>" do
 
   it "returns false if both hashes are identical" do
     h = { a: 1, b: 2 }
-    (h > h).should be_false
+    (h > h).should == false
   end
 end
 
diff --git a/spec/ruby/core/hash/gte_spec.rb b/spec/ruby/core/hash/gte_spec.rb
index 99b89e7217..be5060ea4f 100644
--- a/spec/ruby/core/hash/gte_spec.rb
+++ b/spec/ruby/core/hash/gte_spec.rb
@@ -8,7 +8,7 @@ describe "Hash#>=" do
 
   it "returns true if both hashes are identical" do
     h = { a: 1, b: 2 }
-    (h >= h).should be_true
+    (h >= h).should == true
   end
 end
 
diff --git a/spec/ruby/core/hash/has_key_spec.rb b/spec/ruby/core/hash/has_key_spec.rb
index 4af53579e5..9a6244c6f6 100644
--- a/spec/ruby/core/hash/has_key_spec.rb
+++ b/spec/ruby/core/hash/has_key_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/key'
 
 describe "Hash#has_key?" do
-  it_behaves_like :hash_key_p, :has_key?
+  it "is an alias of Hash#include?" do
+    Hash.instance_method(:has_key?).should == Hash.instance_method(:include?)
+  end
 end
diff --git a/spec/ruby/core/hash/has_value_spec.rb b/spec/ruby/core/hash/has_value_spec.rb
index 39f1627fd3..d40e52ebfd 100644
--- a/spec/ruby/core/hash/has_value_spec.rb
+++ b/spec/ruby/core/hash/has_value_spec.rb
@@ -1,7 +1,16 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/value'
 
 describe "Hash#has_value?" do
-  it_behaves_like :hash_value_p, :has_value?
+  it "returns true if the value exists in the hash" do
+    { a: :b }.has_value?(:a).should == false
+    { 1 => 2 }.has_value?(2).should == true
+    h = Hash.new(5)
+    h.has_value?(5).should == false
+    h = Hash.new { 5 }
+    h.has_value?(5).should == false
+  end
+
+  it "uses == semantics for comparing values" do
+    { 5 => 2.0 }.has_value?(2).should == true
+  end
 end
diff --git a/spec/ruby/core/hash/hash_spec.rb b/spec/ruby/core/hash/hash_spec.rb
index 3649d4d8de..cd67f7a652 100644
--- a/spec/ruby/core/hash/hash_spec.rb
+++ b/spec/ruby/core/hash/hash_spec.rb
@@ -41,4 +41,11 @@ describe "Hash#hash" do
     h.hash.should == {x: [h]}.hash
     # Like above, because h.eql?(x: [h])
   end
+
+  it "allows omitting values" do
+    a = 1
+    b = 2
+
+    {a:, b:}.should == { a: 1, b: 2 }
+  end
 end
diff --git a/spec/ruby/core/hash/include_spec.rb b/spec/ruby/core/hash/include_spec.rb
index f3959dc589..1c32e9fb23 100644
--- a/spec/ruby/core/hash/include_spec.rb
+++ b/spec/ruby/core/hash/include_spec.rb
@@ -1,7 +1,40 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/key'
 
 describe "Hash#include?" do
-  it_behaves_like :hash_key_p, :include?
+  it "returns true if argument is a key" do
+    h = { a: 1, b: 2, c: 3, 4 => 0 }
+    h.include?(:a).should == true
+    h.include?(:b).should == true
+    h.include?(2).should == false
+    h.include?(4).should == true
+
+    not_supported_on :opal do
+      h.include?('b').should == false
+      h.include?(4.0).should == false
+    end
+  end
+
+  it "returns true if the key's matching value was nil" do
+    { xyz: nil }.include?(:xyz).should == true
+  end
+
+  it "returns true if the key's matching value was false" do
+    { xyz: false }.include?(:xyz).should == true
+  end
+
+  it "returns true if the key is nil" do
+    { nil => 'b' }.include?(nil).should == true
+    { nil => nil }.include?(nil).should == true
+  end
+
+  it "compares keys with the same #hash value via #eql?" do
+    x = mock('x')
+    x.stub!(:hash).and_return(42)
+
+    y = mock('y')
+    y.stub!(:hash).and_return(42)
+    y.should_receive(:eql?).and_return(false)
+
+    { x => nil }.include?(y).should == false
+  end
 end
diff --git a/spec/ruby/core/hash/index_spec.rb b/spec/ruby/core/hash/index_spec.rb
deleted file mode 100644
index 2b52c69949..0000000000
--- a/spec/ruby/core/hash/index_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/index'
-
-describe "Hash#index" do
-  it_behaves_like :hash_index, :index
-end
diff --git a/spec/ruby/core/hash/initialize_spec.rb b/spec/ruby/core/hash/initialize_spec.rb
index 00e1174ec8..cdba598813 100644
--- a/spec/ruby/core/hash/initialize_spec.rb
+++ b/spec/ruby/core/hash/initialize_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Hash#initialize" do
   it "is private" do
-    Hash.should have_private_instance_method("initialize")
+    Hash.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "can be used to reset default_proc" do
@@ -42,20 +42,20 @@ describe "Hash#initialize" do
 
   it "returns self" do
     h = Hash.new
-    h.send(:initialize).should equal(h)
+    h.send(:initialize).should.equal?(h)
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
+  it "raises a FrozenError if called on a frozen instance" do
     block = -> { HashSpecs.frozen_hash.instance_eval { initialize() }}
-    block.should raise_error(frozen_error_class)
+    block.should.raise(FrozenError)
 
     block = -> { HashSpecs.frozen_hash.instance_eval { initialize(nil) }  }
-    block.should raise_error(frozen_error_class)
+    block.should.raise(FrozenError)
 
     block = -> { HashSpecs.frozen_hash.instance_eval { initialize(5) }    }
-    block.should raise_error(frozen_error_class)
+    block.should.raise(FrozenError)
 
     block = -> { HashSpecs.frozen_hash.instance_eval { initialize { 5 } } }
-    block.should raise_error(frozen_error_class)
+    block.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/inspect_spec.rb b/spec/ruby/core/hash/inspect_spec.rb
index f41ebb70a6..359b13360f 100644
--- a/spec/ruby/core/hash/inspect_spec.rb
+++ b/spec/ruby/core/hash/inspect_spec.rb
@@ -1,7 +1,123 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/to_s'
 
 describe "Hash#inspect" do
-  it_behaves_like :hash_to_s, :inspect
+  it "returns a string representation with same order as each()" do
+    h = { a: [1, 2], b: -2, d: -6, nil => nil }
+    expected = ruby_version_is("3.4") ? "{a: [1, 2], b: -2, d: -6, nil => nil}" : "{:a=>[1, 2], :b=>-2, :d=>-6, nil=>nil}"
+    h.inspect.should == expected
+  end
+
+  it "calls #inspect on keys and values" do
+    key = mock('key')
+    val = mock('val')
+    key.should_receive(:inspect).and_return('key')
+    val.should_receive(:inspect).and_return('val')
+    expected = ruby_version_is("3.4") ? "{key => val}" : "{key=>val}"
+    { key => val }.inspect.should == expected
+  end
+
+  it "does not call #to_s on a String returned from #inspect" do
+    str = +"abc"
+    str.should_not_receive(:to_s)
+    expected = ruby_version_is("3.4") ? '{a: "abc"}' : '{:a=>"abc"}'
+    { a: str }.inspect.should == expected
+  end
+
+  it "calls #to_s on the object returned from #inspect if the Object isn't a String" do
+    obj = mock("Hash#inspect/to_s calls #to_s")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_return("abc")
+    expected = ruby_version_is("3.4") ? "{a: abc}" : "{:a=>abc}"
+    { a: obj }.inspect.should == expected
+  end
+
+  it "does not call #to_str on the object returned from #inspect when it is not a String" do
+    obj = mock("Hash#inspect/to_s does not call #to_str")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_not_receive(:to_str)
+    expected_pattern = ruby_version_is("3.4") ? /^\{a: #<MockObject:0x[0-9a-f]+>\}$/ : /^\{:a=>#<MockObject:0x[0-9a-f]+>\}$/
+    { a: obj }.inspect.should =~ expected_pattern
+  end
+
+  it "does not call #to_str on the object returned from #to_s when it is not a String" do
+    obj = mock("Hash#inspect/to_s does not call #to_str on #to_s result")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_return(obj)
+    obj.should_not_receive(:to_str)
+    expected_pattern = ruby_version_is("3.4") ? /^\{a: #<MockObject:0x[0-9a-f]+>\}$/ : /^\{:a=>#<MockObject:0x[0-9a-f]+>\}$/
+    { a: obj }.inspect.should =~ expected_pattern
+  end
+
+  it "does not swallow exceptions raised by #to_s" do
+    obj = mock("Hash#inspect/to_s does not swallow #to_s exceptions")
+    obj.should_receive(:inspect).and_return(obj)
+    obj.should_receive(:to_s).and_raise(Exception)
+
+    -> { { a: obj }.inspect }.should.raise(Exception)
+  end
+
+  it "handles hashes with recursive values" do
+    x = {}
+    x[0] = x
+    expected = ruby_version_is("3.4") ? '{0 => {...}}' : '{0=>{...}}'
+    x.inspect.should == expected
+
+    x = {}
+    y = {}
+    x[0] = y
+    y[1] = x
+    expected_x = ruby_version_is("3.4") ? '{0 => {1 => {...}}}' : '{0=>{1=>{...}}}'
+    expected_y = ruby_version_is("3.4") ? '{1 => {0 => {...}}}' : '{1=>{0=>{...}}}'
+    x.inspect.should == expected_x
+    y.inspect.should == expected_y
+  end
+
+  it "does not raise if inspected result is not default external encoding" do
+    utf_16be = mock("utf_16be")
+    utf_16be.should_receive(:inspect).and_return(%<"utf_16be \u3042">.encode(Encoding::UTF_16BE))
+    expected = ruby_version_is("3.4") ? '{a: "utf_16be \u3042"}' : '{:a=>"utf_16be \u3042"}'
+    {a: utf_16be}.inspect.should == expected
+  end
+
+  it "works for keys and values whose #inspect return a frozen String" do
+    expected = ruby_version_is("3.4") ? "{true => false}" : "{true=>false}"
+    { true => false }.inspect.should == expected
+  end
+
+  ruby_version_is "3.4" do
+    it "adds quotes to symbol keys that are not valid symbol literals" do
+      { "needs-quotes": 1 }.inspect.should == '{"needs-quotes": 1}'
+    end
+
+    it "can be evaled" do
+      no_quote = '{a: 1, a!: 1, a?: 1}'
+      eval(no_quote).inspect.should == no_quote
+      [
+        '{"": 1}',
+        '{"0": 1, "!": 1, "%": 1, "&": 1, "*": 1, "+": 1, "-": 1, "/": 1, "<": 1, ">": 1, "^": 1, "`": 1, "|": 1, "~": 1}',
+        '{"@a": 1, "$a": 1, "+@": 1, "a=": 1, "[]": 1}',
+        '{"a\"b": 1, "@@a": 1, "<=>": 1, "===": 1, "[]=": 1}',
+      ].each do |quote|
+        eval(quote).inspect.should == quote
+      end
+    end
+
+    it "can be evaled when Encoding.default_external is changed" do
+      external = Encoding.default_external
+
+      Encoding.default_external = Encoding::ASCII
+      utf8_ascii_hash = '{"\\u3042": 1}'
+      eval(utf8_ascii_hash).inspect.should == utf8_ascii_hash
+
+      Encoding.default_external = Encoding::UTF_8
+      utf8_hash = "{\u3042: 1}"
+      eval(utf8_hash).inspect.should == utf8_hash
+
+      Encoding.default_external = Encoding::Windows_31J
+      sjis_hash = "{\x87]: 1}".dup.force_encoding('sjis')
+      eval(sjis_hash).inspect.should == sjis_hash
+    ensure
+      Encoding.default_external = external
+    end
+  end
 end
diff --git a/spec/ruby/core/hash/invert_spec.rb b/spec/ruby/core/hash/invert_spec.rb
index 73377a9e97..ea441751f2 100644
--- a/spec/ruby/core/hash/invert_spec.rb
+++ b/spec/ruby/core/hash/invert_spec.rb
@@ -24,4 +24,25 @@ describe "Hash#invert" do
     HashSpecs::MyHash[1 => 2, 3 => 4].invert.class.should == Hash
     HashSpecs::MyHash[].invert.class.should == Hash
   end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.invert.default.should == nil
+    h[:a] = 1
+    h.invert.default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.invert.default_proc.should == nil
+    h[:a] = 1
+    h.invert.default_proc.should == nil
+  end
+
+  it "does not retain compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.invert
+    h2.compare_by_identity?.should == false
+  end
 end
diff --git a/spec/ruby/core/hash/keep_if_spec.rb b/spec/ruby/core/hash/keep_if_spec.rb
index 278eafc969..c975efc5f8 100644
--- a/spec/ruby/core/hash/keep_if_spec.rb
+++ b/spec/ruby/core/hash/keep_if_spec.rb
@@ -12,24 +12,24 @@ describe "Hash#keep_if" do
 
   it "keeps every entry for which block is true and returns self" do
     h = { a: 1, b: 2, c: 3, d: 4 }
-    h.keep_if { |k,v| v % 2 == 0 }.should equal(h)
+    h.keep_if { |k,v| v % 2 == 0 }.should.equal?(h)
     h.should == { b: 2, d: 4 }
   end
 
   it "removes all entries if the block is false" do
     h = { a: 1, b: 2, c: 3 }
-    h.keep_if { |k,v| false }.should equal(h)
+    h.keep_if { |k,v| false }.should.equal?(h)
     h.should == {}
   end
 
   it "returns self even if unmodified" do
     h = { 1 => 2, 3 => 4 }
-    h.keep_if { true }.should equal(h)
+    h.keep_if { true }.should.equal?(h)
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.keep_if { true } }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.keep_if { false } }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.keep_if { true } }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.keep_if { false } }.should.raise(FrozenError)
   end
 
   it_behaves_like :hash_iteration_no_block, :keep_if
diff --git a/spec/ruby/core/hash/key_spec.rb b/spec/ruby/core/hash/key_spec.rb
index 73eecbc98e..c2d7049aed 100644
--- a/spec/ruby/core/hash/key_spec.rb
+++ b/spec/ruby/core/hash/key_spec.rb
@@ -1,12 +1,32 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/key'
-require_relative 'shared/index'
 
 describe "Hash#key?" do
-  it_behaves_like :hash_key_p, :key?
+  it "is an alias of Hash#include?" do
+    Hash.instance_method(:key?).should == Hash.instance_method(:include?)
+  end
 end
 
 describe "Hash#key" do
-  it_behaves_like :hash_index, :key
+  it "returns the corresponding key for value" do
+    { 2 => 'a', 1 => 'b' }.key('b').should == 1
+  end
+
+  it "returns nil if the value is not found" do
+    { a: -1, b: 3.14, c: 2.718 }.key(1).should == nil
+  end
+
+  it "doesn't return default value if the value is not found" do
+    Hash.new(5).key(5).should == nil
+  end
+
+  it "compares values using ==" do
+    { 1 => 0 }.key(0.0).should == 1
+    { 1 => 0.0 }.key(0).should == 1
+
+    needle = mock('needle')
+    inhash = mock('inhash')
+    inhash.should_receive(:==).with(needle).and_return(true)
+
+    { 1 => inhash }.key(needle).should == 1
+  end
 end
diff --git a/spec/ruby/core/hash/keys_spec.rb b/spec/ruby/core/hash/keys_spec.rb
index 9a067085e5..789c413bee 100644
--- a/spec/ruby/core/hash/keys_spec.rb
+++ b/spec/ruby/core/hash/keys_spec.rb
@@ -5,11 +5,11 @@ describe "Hash#keys" do
 
   it "returns an array with the keys in the order they were inserted" do
     {}.keys.should == []
-    {}.keys.should be_kind_of(Array)
+    {}.keys.should.is_a?(Array)
     Hash.new(5).keys.should == []
     Hash.new { 5 }.keys.should == []
     { 1 => 2, 4 => 8, 2 => 4 }.keys.should == [1, 4, 2]
-    { 1 => 2, 2 => 4, 4 => 8 }.keys.should be_kind_of(Array)
+    { 1 => 2, 2 => 4, 4 => 8 }.keys.should.is_a?(Array)
     { nil => nil }.keys.should == [nil]
   end
 
diff --git a/spec/ruby/core/hash/length_spec.rb b/spec/ruby/core/hash/length_spec.rb
index d0af0945df..325973306f 100644
--- a/spec/ruby/core/hash/length_spec.rb
+++ b/spec/ruby/core/hash/length_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/length'
 
 describe "Hash#length" do
-  it_behaves_like :hash_length, :length
+  it "is an alias of Hash#size" do
+    Hash.instance_method(:size).should == Hash.instance_method(:length)
+  end
 end
diff --git a/spec/ruby/core/hash/lt_spec.rb b/spec/ruby/core/hash/lt_spec.rb
index 2219615880..4ca326d077 100644
--- a/spec/ruby/core/hash/lt_spec.rb
+++ b/spec/ruby/core/hash/lt_spec.rb
@@ -8,7 +8,7 @@ describe "Hash#<" do
 
   it "returns false if both hashes are identical" do
     h = { a: 1, b: 2 }
-    (h < h).should be_false
+    (h < h).should == false
   end
 end
 
diff --git a/spec/ruby/core/hash/lte_spec.rb b/spec/ruby/core/hash/lte_spec.rb
index a166e5bca4..29e60273d1 100644
--- a/spec/ruby/core/hash/lte_spec.rb
+++ b/spec/ruby/core/hash/lte_spec.rb
@@ -8,7 +8,7 @@ describe "Hash#<=" do
 
   it "returns true if both hashes are identical" do
     h = { a: 1, b: 2 }
-    (h <= h).should be_true
+    (h <= h).should == true
   end
 end
 
diff --git a/spec/ruby/core/hash/member_spec.rb b/spec/ruby/core/hash/member_spec.rb
index 37c0414559..e7309c3f7d 100644
--- a/spec/ruby/core/hash/member_spec.rb
+++ b/spec/ruby/core/hash/member_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/key'
 
 describe "Hash#member?" do
-  it_behaves_like :hash_key_p, :member?
+  it "is an alias of Hash#include?" do
+    Hash.instance_method(:member?).should == Hash.instance_method(:include?)
+  end
 end
diff --git a/spec/ruby/core/hash/merge_spec.rb b/spec/ruby/core/hash/merge_spec.rb
index 91ded30eb7..9e566fcee9 100644
--- a/spec/ruby/core/hash/merge_spec.rb
+++ b/spec/ruby/core/hash/merge_spec.rb
@@ -1,7 +1,5 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/iteration'
-require_relative 'shared/update'
 
 describe "Hash#merge" do
   it "returns a new hash by combining self with the contents of other" do
@@ -30,7 +28,7 @@ describe "Hash#merge" do
 
     -> {
       h1.merge(h2) { |k, x, y| raise(IndexError) }
-    }.should raise_error(IndexError)
+    }.should.raise(IndexError)
 
     r = h1.merge(h1) { |k,x,y| :x }
     r.should == { a: :x, b: :x, d: :x }
@@ -47,8 +45,8 @@ describe "Hash#merge" do
   end
 
   it "returns subclass instance for subclasses" do
-    HashSpecs::MyHash[1 => 2, 3 => 4].merge({ 1 => 2 }).should be_an_instance_of(HashSpecs::MyHash)
-    HashSpecs::MyHash[].merge({ 1 => 2 }).should be_an_instance_of(HashSpecs::MyHash)
+    HashSpecs::MyHash[1 => 2, 3 => 4].merge({ 1 => 2 }).should.instance_of?(HashSpecs::MyHash)
+    HashSpecs::MyHash[].merge({ 1 => 2 }).should.instance_of?(HashSpecs::MyHash)
 
     { 1 => 2, 3 => 4 }.merge(HashSpecs::MyHash[1 => 2]).class.should == Hash
     {}.merge(HashSpecs::MyHash[1 => 2]).class.should == Hash
@@ -81,22 +79,45 @@ describe "Hash#merge" do
     merge_pairs.should == expected_pairs
   end
 
-  ruby_version_is "2.6" do
-    it "accepts multiple hashes" do
-      result = { a: 1 }.merge({ b: 2 }, { c: 3 }, { d: 4 })
-      result.should == { a: 1, b: 2, c: 3, d: 4 }
-    end
+  it "accepts multiple hashes" do
+    result = { a: 1 }.merge({ b: 2 }, { c: 3 }, { d: 4 })
+    result.should == { a: 1, b: 2, c: 3, d: 4 }
+  end
+
+  it "accepts zero arguments and returns a copy of self" do
+    hash = { a: 1 }
+    merged = hash.merge
+
+    merged.should.eql?(hash)
+    merged.should_not.equal?(hash)
+  end
+
+  it "retains the default value" do
+    h = Hash.new(1)
+    h.merge(b: 1, d: 2).default.should == 1
+  end
 
-    it "accepts zero arguments and returns a copy of self" do
-      hash = { a: 1 }
-      merged = hash.merge
+  it "retains the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.merge(b: 1, d: 2).default_proc.should == pr
+  end
 
-      merged.should eql(hash)
-      merged.should_not equal(hash)
-    end
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.merge(b: 1, d: 2)
+    h2.compare_by_identity?.should == true
+  end
+
+  it "ignores compare_by_identity flag of an argument" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = { b: 1, d: 2 }.merge(h)
+    h2.compare_by_identity?.should == false
   end
 end
 
 describe "Hash#merge!" do
-  it_behaves_like :hash_update, :merge!
+  it "is an alias of Hash#update" do
+    Hash.instance_method(:merge!).should == Hash.instance_method(:update)
+  end
 end
diff --git a/spec/ruby/core/hash/new_spec.rb b/spec/ruby/core/hash/new_spec.rb
index 6054b69bdd..207fc2931f 100644
--- a/spec/ruby/core/hash/new_spec.rb
+++ b/spec/ruby/core/hash/new_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
+# Actually these are specs of Hash#initialize, there is no Hash.new it's just Class.new.
 describe "Hash.new" do
   it "creates an empty Hash if passed no arguments" do
     Hash.new.should == {}
@@ -14,7 +15,7 @@ describe "Hash.new" do
 
   it "does not create a copy of the default argument" do
     str = "foo"
-    Hash.new(str).default.should equal(str)
+    Hash.new(str).default.should.equal?(str)
   end
 
   it "creates a Hash with a default_proc if passed a block" do
@@ -26,11 +27,42 @@ describe "Hash.new" do
   end
 
   it "raises an ArgumentError if more than one argument is passed" do
-    -> { Hash.new(5,6) }.should raise_error(ArgumentError)
+    -> { Hash.new(5,6) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed both default argument and default block" do
-    -> { Hash.new(5) { 0 }   }.should raise_error(ArgumentError)
-    -> { Hash.new(nil) { 0 } }.should raise_error(ArgumentError)
+    -> { Hash.new(5) { 0 }   }.should.raise(ArgumentError)
+    -> { Hash.new(nil) { 0 } }.should.raise(ArgumentError)
+  end
+
+  ruby_version_is ""..."3.4" do
+    it "emits a deprecation warning if keyword arguments are passed" do
+      -> { Hash.new(unknown: true) }.should complain(
+        Regexp.new(Regexp.escape("Calling Hash.new with keyword arguments is deprecated and will be removed in Ruby 3.4; use Hash.new({ key: value }) instead"))
+      )
+
+      -> { Hash.new(1, unknown: true) }.should.raise(ArgumentError)
+      -> { Hash.new(unknown: true) { 0 } }.should.raise(ArgumentError)
+
+      Hash.new({ unknown: true }).default.should == { unknown: true }
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "accepts a capacity: argument" do
+      Hash.new(5, capacity: 42).default.should == 5
+      Hash.new(capacity: 42).default.should == nil
+      (Hash.new(capacity: 42) { 1 }).default_proc.should_not == nil
+    end
+
+    it "ignores negative capacity" do
+      -> { Hash.new(capacity: -42) }.should_not.raise
+    end
+
+    it "raises an error if unknown keyword arguments are passed" do
+      -> { Hash.new(unknown: true) }.should.raise(ArgumentError)
+      -> { Hash.new(1, unknown: true) }.should.raise(ArgumentError)
+      -> { Hash.new(unknown: true) { 0 } }.should.raise(ArgumentError)
+    end
   end
 end
diff --git a/spec/ruby/core/hash/rassoc_spec.rb b/spec/ruby/core/hash/rassoc_spec.rb
index f3b2a6de20..73379f6867 100644
--- a/spec/ruby/core/hash/rassoc_spec.rb
+++ b/spec/ruby/core/hash/rassoc_spec.rb
@@ -6,7 +6,7 @@ describe "Hash#rassoc" do
   end
 
   it "returns an Array if the argument is a value of the Hash" do
-    @h.rassoc(:green).should be_an_instance_of(Array)
+    @h.rassoc(:green).should.instance_of?(Array)
   end
 
   it "returns a 2-element Array if the argument is a value of the Hash" do
@@ -28,15 +28,15 @@ describe "Hash#rassoc" do
   it "uses #== to compare the argument to the values" do
     @h[:key] = 1.0
     1.should == 1.0
-    @h.rassoc(1).should eql [:key, 1.0]
+    @h.rassoc(1).should.eql? [:key, 1.0]
   end
 
   it "returns nil if the argument is not a value of the Hash" do
-    @h.rassoc(:banana).should be_nil
+    @h.rassoc(:banana).should == nil
   end
 
   it "returns nil if the argument is not a value of the Hash even when there is a default" do
-    Hash.new(42).merge!( foo: :bar ).rassoc(42).should be_nil
-    Hash.new{|h, k| h[k] = 42}.merge!( foo: :bar ).rassoc(42).should be_nil
+    Hash.new(42).merge!( foo: :bar ).rassoc(42).should == nil
+    Hash.new{|h, k| h[k] = 42}.merge!( foo: :bar ).rassoc(42).should == nil
   end
 end
diff --git a/spec/ruby/core/hash/rehash_spec.rb b/spec/ruby/core/hash/rehash_spec.rb
index 587935fc43..fcd5a037bd 100644
--- a/spec/ruby/core/hash/rehash_spec.rb
+++ b/spec/ruby/core/hash/rehash_spec.rb
@@ -20,7 +20,7 @@ describe "Hash#rehash" do
 
     h.keys.include?(k1).should == true
 
-    h.rehash.should equal(h)
+    h.rehash.should.equal?(h)
     h.key?(k1).should == true
     h[k1].should == :v1
   end
@@ -59,8 +59,56 @@ describe "Hash#rehash" do
     h.keys.should == [a]
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.rehash  }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.rehash }.should raise_error(frozen_error_class)
+  it "removes duplicate keys for large hashes" do
+    a = [1,2]
+    b = [1]
+
+    h = {}
+    h[a] = true
+    h[b] = true
+    100.times { |n| h[n] = true }
+    b << 2
+    h.size.should == 102
+    h.keys.should.include? a
+    h.keys.should.include? b
+    h.rehash
+    h.size.should == 101
+    h.keys.should.include? a
+    h.keys.should_not.include? [1]
+  end
+
+  it "iterates keys in insertion order" do
+    key = Class.new do
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+      end
+
+      def hash
+        123
+      end
+    end
+
+    a, b, c, d = key.new('a'), key.new('b'), key.new('c'), key.new('d')
+    h = { a => 1, b => 2, c => 3, d => 4 }
+    h.size.should == 4
+
+    key.class_exec do
+      def eql?(other)
+        true
+      end
+    end
+
+    h.rehash
+    h.size.should == 1
+    k, v = h.first
+    k.name.should == 'a'
+    v.should == 4
+  end
+
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.rehash  }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.rehash }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/hash/reject_spec.rb b/spec/ruby/core/hash/reject_spec.rb
index 8016be5e83..aa1a074897 100644
--- a/spec/ruby/core/hash/reject_spec.rb
+++ b/spec/ruby/core/hash/reject_spec.rb
@@ -28,13 +28,8 @@ describe "Hash#reject" do
 
   context "with extra state" do
     it "returns Hash instance for subclasses" do
-      HashSpecs::MyHash[1 => 2, 3 => 4].reject { false }.should be_kind_of(Hash)
-      HashSpecs::MyHash[1 => 2, 3 => 4].reject { true }.should be_kind_of(Hash)
-    end
-
-    it "does not taint the resulting hash" do
-      h = { a: 1 }.taint
-      h.reject {false}.tainted?.should == false
+      HashSpecs::MyHash[1 => 2, 3 => 4].reject { false }.should.is_a?(Hash)
+      HashSpecs::MyHash[1 => 2, 3 => 4].reject { true }.should.is_a?(Hash)
     end
   end
 
@@ -49,6 +44,27 @@ describe "Hash#reject" do
     reject_pairs.should == reject_bang_pairs
   end
 
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.reject { false }.default.should == nil
+    h[:a] = 1
+    h.reject { false }.default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.reject { false }.default_proc.should == nil
+    h[:a] = 1
+    h.reject { false }.default_proc.should == nil
+  end
+
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.reject { |k, _| k == :a }
+    h2.compare_by_identity?.should == true
+  end
+
   it_behaves_like :hash_iteration_no_block, :reject
   it_behaves_like :enumeratorized_with_origin_size, :reject, { 1 => 2, 3 => 4, 5 => 6 }
 end
@@ -63,7 +79,7 @@ describe "Hash#reject!" do
 
   it "removes all entries if the block is true" do
     h = { a: 1, b: 2, c: 3 }
-    h.reject! { |k,v| true }.should equal(h)
+    h.reject! { |k,v| true }.should.equal?(h)
     h.should == {}
   end
 
@@ -87,12 +103,12 @@ describe "Hash#reject!" do
     reject_bang_pairs.should == delete_if_pairs
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance that is modified" do
-    -> { HashSpecs.empty_frozen_hash.reject! { true } }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance that is modified" do
+    -> { HashSpecs.empty_frozen_hash.reject! { true } }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance that would not be modified" do
-    -> { HashSpecs.frozen_hash.reject! { false } }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance that would not be modified" do
+    -> { HashSpecs.frozen_hash.reject! { false } }.should.raise(FrozenError)
   end
 
   it_behaves_like :hash_iteration_no_block, :reject!
diff --git a/spec/ruby/core/hash/replace_spec.rb b/spec/ruby/core/hash/replace_spec.rb
index 92b2118fd3..4dacbf9779 100644
--- a/spec/ruby/core/hash/replace_spec.rb
+++ b/spec/ruby/core/hash/replace_spec.rb
@@ -1,7 +1,79 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/replace'
 
 describe "Hash#replace" do
-  it_behaves_like :hash_replace, :replace
+  it "replaces the contents of self with other" do
+    h = { a: 1, b: 2 }
+    h.replace(c: -1, d: -2).should.equal?(h)
+    h.should == { c: -1, d: -2 }
+  end
+
+  it "tries to convert the passed argument to a hash using #to_hash" do
+    obj = mock('{1=>2,3=>4}')
+    obj.should_receive(:to_hash).and_return({ 1 => 2, 3 => 4 })
+
+    h = {}
+    h.replace(obj)
+    h.should == { 1 => 2, 3 => 4 }
+  end
+
+  it "calls to_hash on hash subclasses" do
+    h = {}
+    h.replace(HashSpecs::ToHashHash[1 => 2])
+    h.should == { 1 => 2 }
+  end
+
+  it "does not retain the default value" do
+    hash = Hash.new(1)
+    hash.replace(b: 2).default.should == nil
+  end
+
+  it "transfers the default value of an argument" do
+    hash = Hash.new(1)
+    { a: 1 }.replace(hash).default.should == 1
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    hash = Hash.new(&pr)
+    hash.replace(b: 2).default_proc.should == nil
+  end
+
+  it "transfers the default_proc of an argument" do
+    pr = proc { |h, k| h[k] = [] }
+    hash = Hash.new(&pr)
+    { a: 1 }.replace(hash).default_proc.should == pr
+  end
+
+  it "does not call the default_proc of an argument" do
+    hash_a = Hash.new { |h, k| k * 5 }
+    hash_b = Hash.new(-> { raise "Should not invoke lambda" })
+    hash_a.replace(hash_b)
+    hash_a.default.should == hash_b.default
+  end
+
+  it "transfers compare_by_identity flag of an argument" do
+    h = { a: 1, c: 3 }
+    h2 = { b: 2, d: 4 }.compare_by_identity
+    h.replace(h2)
+    h.compare_by_identity?.should == true
+  end
+
+  it "does not retain compare_by_identity flag" do
+    h = { a: 1, c: 3 }.compare_by_identity
+    h.replace(b: 2, d: 4)
+    h.compare_by_identity?.should == false
+  end
+
+  it "raises a FrozenError if called on a frozen instance that would not be modified" do
+    -> do
+      HashSpecs.frozen_hash.replace(HashSpecs.frozen_hash)
+    end.should.raise(FrozenError)
+  end
+
+  it "raises a FrozenError if called on a frozen instance that is modified" do
+    -> do
+      HashSpecs.frozen_hash.replace(HashSpecs.empty_frozen_hash)
+    end.should.raise(FrozenError)
+  end
 end
diff --git a/spec/ruby/core/hash/ruby2_keywords_hash_spec.rb b/spec/ruby/core/hash/ruby2_keywords_hash_spec.rb
new file mode 100644
index 0000000000..609a53f81f
--- /dev/null
+++ b/spec/ruby/core/hash/ruby2_keywords_hash_spec.rb
@@ -0,0 +1,81 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Hash.ruby2_keywords_hash?" do
+  it "returns false if the Hash is not a keywords Hash" do
+    Hash.ruby2_keywords_hash?({}).should == false
+  end
+
+  it "returns true if the Hash is a keywords Hash marked by Module#ruby2_keywords" do
+    obj = Class.new {
+      ruby2_keywords def m(*args)
+        args.last
+      end
+    }.new
+    Hash.ruby2_keywords_hash?(obj.m(a: 1)).should == true
+  end
+
+  it "raises TypeError for non-Hash" do
+    -> { Hash.ruby2_keywords_hash?(nil) }.should.raise(TypeError)
+  end
+end
+
+describe "Hash.ruby2_keywords_hash" do
+  it "returns a copy of a Hash and marks the copy as a keywords Hash" do
+    h = {a: 1}.freeze
+    kw = Hash.ruby2_keywords_hash(h)
+    Hash.ruby2_keywords_hash?(h).should == false
+    Hash.ruby2_keywords_hash?(kw).should == true
+    kw.should == h
+  end
+
+  it "returns an instance of the subclass if called on an instance of a subclass of Hash" do
+    h = HashSpecs::MyHash.new
+    h[:a] = 1
+    kw = Hash.ruby2_keywords_hash(h)
+    kw.class.should == HashSpecs::MyHash
+    Hash.ruby2_keywords_hash?(h).should == false
+    Hash.ruby2_keywords_hash?(kw).should == true
+    kw.should == h
+  end
+
+  it "copies instance variables" do
+    h = {a: 1}
+    h.instance_variable_set(:@foo, 42)
+    kw = Hash.ruby2_keywords_hash(h)
+    kw.instance_variable_get(:@foo).should == 42
+  end
+
+  it "copies the hash internals" do
+    h = {a: 1}
+    kw = Hash.ruby2_keywords_hash(h)
+    h[:a] = 2
+    kw[:a].should == 1
+  end
+
+  it "raises TypeError for non-Hash" do
+    -> { Hash.ruby2_keywords_hash(nil) }.should.raise(TypeError)
+  end
+
+  it "retains the default value" do
+    hash = Hash.new(1)
+    Hash.ruby2_keywords_hash(hash).default.should == 1
+    hash[:a] = 1
+    Hash.ruby2_keywords_hash(hash).default.should == 1
+  end
+
+  it "retains the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    hash = Hash.new(&pr)
+    Hash.ruby2_keywords_hash(hash).default_proc.should == pr
+    hash[:a] = 1
+    Hash.ruby2_keywords_hash(hash).default_proc.should == pr
+  end
+
+  it "retains compare_by_identity_flag" do
+    hash = {}.compare_by_identity
+    Hash.ruby2_keywords_hash(hash).compare_by_identity?.should == true
+    hash[:a] = 1
+    Hash.ruby2_keywords_hash(hash).compare_by_identity?.should == true
+  end
+end
diff --git a/spec/ruby/core/hash/select_spec.rb b/spec/ruby/core/hash/select_spec.rb
index 38b0180b0e..60b2ce67c1 100644
--- a/spec/ruby/core/hash/select_spec.rb
+++ b/spec/ruby/core/hash/select_spec.rb
@@ -1,10 +1,112 @@
 require_relative '../../spec_helper'
-require_relative 'shared/select'
+require_relative '../enumerable/shared/enumeratorized'
+require_relative 'fixtures/classes'
+require_relative 'shared/iteration'
 
 describe "Hash#select" do
-  it_behaves_like :hash_select, :select
+  before :each do
+    @hsh = { 1 => 2, 3 => 4, 5 => 6 }
+    @empty = {}
+  end
+
+  it "yields two arguments: key and value" do
+    all_args = []
+    { 1 => 2, 3 => 4 }.select { |*args| all_args << args }
+    all_args.sort.should == [[1, 2], [3, 4]]
+  end
+
+  it "returns a Hash of entries for which block is true" do
+    a_pairs = { 'a' => 9, 'c' => 4, 'b' => 5, 'd' => 2 }.select { |k,v| v % 2 == 0 }
+    a_pairs.should.instance_of?(Hash)
+    a_pairs.sort.should == [['c', 4], ['d', 2]]
+  end
+
+  it "processes entries with the same order as reject" do
+    h = { a: 9, c: 4, b: 5, d: 2 }
+
+    select_pairs = []
+    reject_pairs = []
+    h.dup.select{ |*pair| select_pairs << pair }
+    h.reject { |*pair| reject_pairs << pair }
+
+    select_pairs.should == reject_pairs
+  end
+
+  it "returns an Enumerator when called on a non-empty hash without a block" do
+    @hsh.select.should.instance_of?(Enumerator)
+  end
+
+  it "returns an Enumerator when called on an empty hash without a block" do
+    @empty.select.should.instance_of?(Enumerator)
+  end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.select { true }.default.should == nil
+    h[:a] = 1
+    h.select { true }.default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.select { true }.default_proc.should == nil
+    h[:a] = 1
+    h.select { true }.default_proc.should == nil
+  end
+
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.select { |k, _| k == :a }
+    h2.compare_by_identity?.should == true
+  end
+
+  it_behaves_like :hash_iteration_no_block, :select
+
+  before :each do
+    @object = { 1 => 2, 3 => 4, 5 => 6 }
+  end
+  it_behaves_like :enumeratorized_with_origin_size, :select
 end
 
 describe "Hash#select!" do
-  it_behaves_like :hash_select!, :select!
+  before :each do
+    @hsh = { 1 => 2, 3 => 4, 5 => 6 }
+    @empty = {}
+  end
+
+  it "is equivalent to keep_if if changes are made" do
+    h = { a: 2 }
+    h.select! { |k,v| v <= 1 }.should.equal? h
+
+    h = { 1 => 2, 3 => 4 }
+    all_args_select = []
+    h.dup.select! { |*args| all_args_select << args }
+    all_args_select.should == [[1, 2], [3, 4]]
+  end
+
+  it "removes all entries if the block is false" do
+    h = { a: 1, b: 2, c: 3 }
+    h.select! { |k,v| false }.should.equal?(h)
+    h.should == {}
+  end
+
+  it "returns nil if no changes were made" do
+    { a: 1 }.select! { |k,v| v <= 1 }.should == nil
+  end
+
+  it "raises a FrozenError if called on an empty frozen instance" do
+    -> { HashSpecs.empty_frozen_hash.select! { false } }.should.raise(FrozenError)
+  end
+
+  it "raises a FrozenError if called on a frozen instance that would not be modified" do
+    -> { HashSpecs.frozen_hash.select! { true } }.should.raise(FrozenError)
+  end
+
+  it_behaves_like :hash_iteration_no_block, :select!
+
+  before :each do
+    @object = { 1 => 2, 3 => 4, 5 => 6 }
+  end
+  it_behaves_like :enumeratorized_with_origin_size, :select!
 end
diff --git a/spec/ruby/core/hash/shared/comparison.rb b/spec/ruby/core/hash/shared/comparison.rb
index 07564e4cec..2b62837232 100644
--- a/spec/ruby/core/hash/shared/comparison.rb
+++ b/spec/ruby/core/hash/shared/comparison.rb
@@ -1,15 +1,15 @@
 describe :hash_comparison, shared: true do
   it "raises a TypeError if the right operand is not a hash" do
-    -> { { a: 1 }.send(@method, 1) }.should raise_error(TypeError)
-    -> { { a: 1 }.send(@method, nil) }.should raise_error(TypeError)
-    -> { { a: 1 }.send(@method, []) }.should raise_error(TypeError)
+    -> { { a: 1 }.send(@method, 1) }.should.raise(TypeError)
+    -> { { a: 1 }.send(@method, nil) }.should.raise(TypeError)
+    -> { { a: 1 }.send(@method, []) }.should.raise(TypeError)
   end
 
   it "returns false if both hashes have the same keys but different values" do
     h1 = { a: 1 }
     h2 = { a: 2 }
 
-    h1.send(@method, h2).should be_false
-    h2.send(@method, h1).should be_false
+    h1.send(@method, h2).should == false
+    h2.send(@method, h1).should == false
   end
 end
diff --git a/spec/ruby/core/hash/shared/each.rb b/spec/ruby/core/hash/shared/each.rb
deleted file mode 100644
index d1f2e5f672..0000000000
--- a/spec/ruby/core/hash/shared/each.rb
+++ /dev/null
@@ -1,85 +0,0 @@
-describe :hash_each, shared: true do
-
-  # This is inconsistent with below, MRI checks the block arity in rb_hash_each_pair()
-  it "yields a [[key, value]] Array for each pair to a block expecting |*args|" do
-    all_args = []
-    { 1 => 2, 3 => 4 }.send(@method) { |*args| all_args << args }
-    all_args.sort.should == [[[1, 2]], [[3, 4]]]
-  end
-
-  it "yields the key and value of each pair to a block expecting |key, value|" do
-    r = {}
-    h = { a: 1, b: 2, c: 3, d: 5 }
-    h.send(@method) { |k,v| r[k.to_s] = v.to_s }.should equal(h)
-    r.should == { "a" => "1", "b" => "2", "c" => "3", "d" => "5" }
-  end
-
-  it "yields the key only to a block expecting |key,|" do
-    ary = []
-    h = { "a" => 1, "b" => 2, "c" => 3 }
-    h.send(@method) { |k,| ary << k }
-    ary.sort.should == ["a", "b", "c"]
-  end
-
-  it "yields 2 values and not an Array of 2 elements when given a callable of arity 2" do
-    obj = Object.new
-    def obj.foo(key, value)
-      ScratchPad << key << value
-    end
-
-    ScratchPad.record([])
-    { "a" => 1 }.send(@method, &obj.method(:foo))
-    ScratchPad.recorded.should == ["a", 1]
-
-    ScratchPad.record([])
-    { "a" => 1 }.send(@method, &-> key, value { ScratchPad << key << value })
-    ScratchPad.recorded.should == ["a", 1]
-  end
-
-  it "uses the same order as keys() and values()" do
-    h = { a: 1, b: 2, c: 3, d: 5 }
-    keys = []
-    values = []
-
-    h.send(@method) do |k, v|
-      keys << k
-      values << v
-    end
-
-    keys.should == h.keys
-    values.should == h.values
-  end
-
-  # Confirming the argument-splatting works from child class for both k, v and [k, v]
-  it "properly expands (or not) child class's 'each'-yielded args" do
-    cls1 = Class.new(Hash) do
-      attr_accessor :k_v
-      def each
-        super do |k, v|
-          @k_v = [k, v]
-          yield k, v
-        end
-      end
-    end
-
-    cls2 = Class.new(Hash) do
-      attr_accessor :k_v
-      def each
-        super do |k, v|
-          @k_v = [k, v]
-          yield([k, v])
-        end
-      end
-    end
-
-    obj1 = cls1.new
-    obj1['a'] = 'b'
-    obj1.map {|k, v| [k, v]}.should == [['a', 'b']]
-    obj1.k_v.should == ['a', 'b']
-
-    obj2 = cls2.new
-    obj2['a'] = 'b'
-    obj2.map {|k, v| [k, v]}.should == [['a', 'b']]
-    obj2.k_v.should == ['a', 'b']
-  end
-end
diff --git a/spec/ruby/core/hash/shared/eql.rb b/spec/ruby/core/hash/shared/eql.rb
index 1aed5f51fb..512e1ad016 100644
--- a/spec/ruby/core/hash/shared/eql.rb
+++ b/spec/ruby/core/hash/shared/eql.rb
@@ -3,7 +3,7 @@ describe :hash_eql, shared: true do
     value = mock('x')
     value.should_not_receive(:==)
     value.should_not_receive(:eql?)
-    { 1 => value }.send(@method, { 2 => value }).should be_false
+    { 1 => value }.send(@method, { 2 => value }).should == false
   end
 
   it "returns false when the numbers of keys differ without comparing any elements" do
@@ -13,8 +13,8 @@ describe :hash_eql, shared: true do
     obj.should_not_receive(:==)
     obj.should_not_receive(:eql?)
 
-    {}.send(@method, h).should be_false
-    h.send(@method, {}).should be_false
+    {}.send(@method, h).should == false
+    h.send(@method, {}).should == false
   end
 
   it "first compares keys via hash" do
@@ -23,7 +23,7 @@ describe :hash_eql, shared: true do
     y = mock('y')
     y.should_receive(:hash).any_number_of_times.and_return(0)
 
-    { x => 1 }.send(@method, { y => 1 }).should be_false
+    { x => 1 }.send(@method, { y => 1 }).should == false
   end
 
   it "does not compare keys with different hash codes via eql?" do
@@ -35,39 +35,39 @@ describe :hash_eql, shared: true do
     x.should_receive(:hash).any_number_of_times.and_return(0)
     y.should_receive(:hash).any_number_of_times.and_return(1)
 
-    { x => 1 }.send(@method, { y => 1 }).should be_false
+    { x => 1 }.send(@method, { y => 1 }).should == false
   end
 
   it "computes equality for recursive hashes" do
     h = {}
     h[:a] = h
-    h.send(@method, h[:a]).should be_true
-    (h == h[:a]).should be_true
+    h.send(@method, h[:a]).should == true
+    (h == h[:a]).should == true
   end
 
   it "doesn't call to_hash on objects" do
     mock_hash = mock("fake hash")
     def mock_hash.to_hash() {} end
-    {}.send(@method, mock_hash).should be_false
+    {}.send(@method, mock_hash).should == false
   end
 
   it "computes equality for complex recursive hashes" do
     a, b = {}, {}
     a.merge! self: a, other: b
     b.merge! self: b, other: a
-    a.send(@method, b).should be_true # they both have the same structure!
+    a.send(@method, b).should == true # they both have the same structure!
 
     c = {}
     c.merge! other: c, self: c
-    c.send(@method, a).should be_true # subtle, but they both have the same structure!
+    c.send(@method, a).should == true # subtle, but they both have the same structure!
     a[:delta] = c[:delta] = a
-    c.send(@method, a).should be_false # not quite the same structure, as a[:other][:delta] = nil
+    c.send(@method, a).should == false # not quite the same structure, as a[:other][:delta] = nil
     c[:delta] = 42
-    c.send(@method, a).should be_false
+    c.send(@method, a).should == false
     a[:delta] = 42
-    c.send(@method, a).should be_false
+    c.send(@method, a).should == false
     b[:delta] = 42
-    c.send(@method, a).should be_true
+    c.send(@method, a).should == true
   end
 
   it "computes equality for recursive hashes & arrays" do
@@ -76,19 +76,19 @@ describe :hash_eql, shared: true do
     x << a
     y << c
     z << b
-    b.send(@method, c).should be_true # they clearly have the same structure!
-    y.send(@method, z).should be_true
-    a.send(@method, b).should be_true # subtle, but they both have the same structure!
-    x.send(@method, y).should be_true
+    b.send(@method, c).should == true # they clearly have the same structure!
+    y.send(@method, z).should == true
+    a.send(@method, b).should == true # subtle, but they both have the same structure!
+    x.send(@method, y).should == true
     y << x
-    y.send(@method, z).should be_false
+    y.send(@method, z).should == false
     z << x
-    y.send(@method, z).should be_true
+    y.send(@method, z).should == true
 
     a[:foo], a[:bar] = a[:bar], a[:foo]
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
     b[:bar] = b[:foo]
-    b.send(@method, c).should be_false
+    b.send(@method, c).should == false
   end
 end
 
@@ -100,7 +100,7 @@ describe :hash_eql_additional, shared: true do
     def y.==(o) false end
     def x.eql?(o) false end
     def y.eql?(o) false end
-    { 1 => x }.send(@method, { 1 => y }).should be_false
+    { 1 => x }.send(@method, { 1 => y }).should == false
 
     x = mock('x')
     y = mock('y')
@@ -108,45 +108,45 @@ describe :hash_eql_additional, shared: true do
     def y.==(o) true end
     def x.eql?(o) true end
     def y.eql?(o) true end
-    { 1 => x }.send(@method, { 1 => y }).should be_true
+    { 1 => x }.send(@method, { 1 => y }).should == true
   end
 
   it "compares keys with eql? semantics" do
-    { 1.0 => "x" }.send(@method, { 1.0 => "x" }).should be_true
-    { 1.0 => "x" }.send(@method, { 1.0 => "x" }).should be_true
-    { 1 => "x" }.send(@method, { 1.0 => "x" }).should be_false
-    { 1.0 => "x" }.send(@method, { 1 => "x" }).should be_false
+    { 1.0 => "x" }.send(@method, { 1.0 => "x" }).should == true
+    { 1.0 => "x" }.send(@method, { 1.0 => "x" }).should == true
+    { 1 => "x" }.send(@method, { 1.0 => "x" }).should == false
+    { 1.0 => "x" }.send(@method, { 1 => "x" }).should == false
   end
 
-  it "returns true iff other Hash has the same number of keys and each key-value pair matches" do
+  it "returns true if and only if other Hash has the same number of keys and each key-value pair matches" do
     a = { a: 5 }
     b = {}
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
 
     b[:a] = 5
-    a.send(@method, b).should be_true
+    a.send(@method, b).should == true
 
     not_supported_on :opal do
       c = { "a" => 5 }
-      a.send(@method, c).should be_false
+      a.send(@method, c).should == false
     end
 
     c = { "A" => 5 }
-    a.send(@method, c).should be_false
+    a.send(@method, c).should == false
 
     c = { a: 6 }
-    a.send(@method, c).should be_false
+    a.send(@method, c).should == false
   end
 
   it "does not call to_hash on hash subclasses" do
-    { 5 => 6 }.send(@method, HashSpecs::ToHashHash[5 => 6]).should be_true
+    { 5 => 6 }.send(@method, HashSpecs::ToHashHash[5 => 6]).should == true
   end
 
   it "ignores hash class differences" do
     h = { 1 => 2, 3 => 4 }
-    HashSpecs::MyHash[h].send(@method, h).should be_true
-    HashSpecs::MyHash[h].send(@method, HashSpecs::MyHash[h]).should be_true
-    h.send(@method, HashSpecs::MyHash[h]).should be_true
+    HashSpecs::MyHash[h].send(@method, h).should == true
+    HashSpecs::MyHash[h].send(@method, HashSpecs::MyHash[h]).should == true
+    h.send(@method, HashSpecs::MyHash[h]).should == true
   end
 
   # Why isn't this true of eql? too ?
@@ -155,40 +155,28 @@ describe :hash_eql_additional, shared: true do
       obj = mock('0')
       obj.should_receive(:hash).at_least(1).and_return(0)
 
-      # It's undefined whether the impl does a[0].eql?(a[1]) or
-      # a[1].eql?(a[0]) so we taint both.
       def obj.eql?(o)
         return true if self.equal?(o)
-        taint
-        o.taint
         false
       end
 
       obj
     end
 
-    { a[0] => 1 }.send(@method, { a[1] => 1 }).should be_false
-    a[0].tainted?.should be_true
-    a[1].tainted?.should be_true
+    { a[0] => 1 }.send(@method, { a[1] => 1 }).should == false
 
     a = Array.new(2) do
       obj = mock('0')
       obj.should_receive(:hash).at_least(1).and_return(0)
 
       def obj.eql?(o)
-        # It's undefined whether the impl does a[0].send(@method, a[1]) or
-        # a[1].send(@method, a[0]) so we taint both.
-        taint
-        o.taint
         true
       end
 
       obj
     end
 
-    { a[0] => 1 }.send(@method, { a[1] => 1 }).should be_true
-    a[0].tainted?.should be_true
-    a[1].tainted?.should be_true
+    { a[0] => 1 }.send(@method, { a[1] => 1 }).should == true
   end
 
   it "compares the values in self to values in other hash" do
@@ -197,20 +185,20 @@ describe :hash_eql_additional, shared: true do
 
     l_val.should_receive(:eql?).with(r_val).and_return(true)
 
-    { 1 => l_val }.eql?({ 1 => r_val }).should be_true
+    { 1 => l_val }.eql?({ 1 => r_val }).should == true
   end
 end
 
 describe :hash_eql_additional_more, shared: true do
   it "returns true if other Hash has the same number of keys and each key-value pair matches, even though the default-value are not same" do
-    Hash.new(5).send(@method, Hash.new(1)).should be_true
-    Hash.new {|h, k| 1}.send(@method, Hash.new {}).should be_true
-    Hash.new {|h, k| 1}.send(@method, Hash.new(2)).should be_true
+    Hash.new(5).send(@method, Hash.new(1)).should == true
+    Hash.new {|h, k| 1}.send(@method, Hash.new {}).should == true
+    Hash.new {|h, k| 1}.send(@method, Hash.new(2)).should == true
 
     d = Hash.new {|h, k| 1}
     e = Hash.new {}
     d[1] = 2
     e[1] = 2
-    d.send(@method, e).should be_true
+    d.send(@method, e).should == true
   end
 end
diff --git a/spec/ruby/core/hash/shared/equal.rb b/spec/ruby/core/hash/shared/equal.rb
deleted file mode 100644
index 43606437fe..0000000000
--- a/spec/ruby/core/hash/shared/equal.rb
+++ /dev/null
@@ -1,90 +0,0 @@
-describe :hash_equal, shared: true do
-  it "does not compare values when keys don't match" do
-    value = mock('x')
-    value.should_not_receive(:==)
-    value.should_not_receive(:eql?)
-    { 1 => value }.send(@method, { 2 => value }).should be_false
-  end
-
-  it "returns false when the numbers of keys differ without comparing any elements" do
-    obj = mock('x')
-    h = { obj => obj }
-
-    obj.should_not_receive(:==)
-    obj.should_not_receive(:eql?)
-
-    {}.send(@method, h).should be_false
-    h.send(@method, {}).should be_false
-  end
-
-  it "first compares keys via hash" do
-    x = mock('x')
-    x.should_receive(:hash).and_return(0)
-    y = mock('y')
-    y.should_receive(:hash).and_return(0)
-
-    { x => 1 }.send(@method, { y => 1 }).should be_false
-  end
-
-  it "does not compare keys with different hash codes via eql?" do
-    x = mock('x')
-    y = mock('y')
-    x.should_not_receive(:eql?)
-    y.should_not_receive(:eql?)
-
-    x.should_receive(:hash).and_return(0)
-    y.should_receive(:hash).and_return(1)
-
-    def x.hash() 0 end
-    def y.hash() 1 end
-
-    { x => 1 }.send(@method, { y => 1 }).should be_false
-  end
-
-  it "computes equality for recursive hashes" do
-    h = {}
-    h[:a] = h
-    h.send(@method, h[:a]).should be_true
-    (h == h[:a]).should be_true
-  end
-
-  it "computes equality for complex recursive hashes" do
-    a, b = {}, {}
-    a.merge! self: a, other: b
-    b.merge! self: b, other: a
-    a.send(@method, b).should be_true # they both have the same structure!
-
-    c = {}
-    c.merge! other: c, self: c
-    c.send(@method, a).should be_true # subtle, but they both have the same structure!
-    a[:delta] = c[:delta] = a
-    c.send(@method, a).should be_false # not quite the same structure, as a[:other][:delta] = nil
-    c[:delta] = 42
-    c.send(@method, a).should be_false
-    a[:delta] = 42
-    c.send(@method, a).should be_false
-    b[:delta] = 42
-    c.send(@method, a).should be_true
-  end
-
-  it "computes equality for recursive hashes & arrays" do
-    x, y, z = [], [], []
-    a, b, c = {foo: x, bar: 42}, {foo: y, bar: 42}, {foo: z, bar: 42}
-    x << a
-    y << c
-    z << b
-    b.send(@method, c).should be_true # they clearly have the same structure!
-    y.send(@method, z).should be_true
-    a.send(@method, b).should be_true # subtle, but they both have the same structure!
-    x.send(@method, y).should be_true
-    y << x
-    y.send(@method, z).should be_false
-    z << x
-    y.send(@method, z).should be_true
-
-    a[:foo], a[:bar] = a[:bar], a[:foo]
-    a.send(@method, b).should be_false
-    b[:bar] = b[:foo]
-    b.send(@method, c).should be_false
-  end
-end
diff --git a/spec/ruby/core/hash/shared/greater_than.rb b/spec/ruby/core/hash/shared/greater_than.rb
index 1f8b9fcfb7..dfe0b80250 100644
--- a/spec/ruby/core/hash/shared/greater_than.rb
+++ b/spec/ruby/core/hash/shared/greater_than.rb
@@ -5,11 +5,11 @@ describe :hash_greater_than, shared: true do
   end
 
   it "returns true if the other hash is a subset of self" do
-    @h1.send(@method, @h2).should be_true
+    @h1.send(@method, @h2).should == true
   end
 
   it "returns false if the other hash is not a subset of self" do
-    @h2.send(@method, @h1).should be_false
+    @h2.send(@method, @h1).should == false
   end
 
   it "converts the right operand to a hash before comparing" do
@@ -18,6 +18,6 @@ describe :hash_greater_than, shared: true do
       { a: 1, b: 2 }
     end
 
-    @h1.send(@method, o).should be_true
+    @h1.send(@method, o).should == true
   end
 end
diff --git a/spec/ruby/core/hash/shared/index.rb b/spec/ruby/core/hash/shared/index.rb
deleted file mode 100644
index 4858ba85f5..0000000000
--- a/spec/ruby/core/hash/shared/index.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../fixtures/classes'
-
-describe :hash_index, shared: true do
-  it "returns the corresponding key for value" do
-    { 2 => 'a', 1 => 'b' }.send(@method, 'b').should == 1
-  end
-
-  it "returns nil if the value is not found" do
-    { a: -1, b: 3.14, c: 2.718 }.send(@method, 1).should be_nil
-  end
-
-  it "doesn't return default value if the value is not found" do
-    Hash.new(5).send(@method, 5).should be_nil
-  end
-
-  it "compares values using ==" do
-    { 1 => 0 }.send(@method, 0.0).should == 1
-    { 1 => 0.0 }.send(@method, 0).should == 1
-
-    needle = mock('needle')
-    inhash = mock('inhash')
-    inhash.should_receive(:==).with(needle).and_return(true)
-
-    { 1 => inhash }.send(@method, needle).should == 1
-  end
-end
diff --git a/spec/ruby/core/hash/shared/iteration.rb b/spec/ruby/core/hash/shared/iteration.rb
index d27c2443f8..322e4b9a2f 100644
--- a/spec/ruby/core/hash/shared/iteration.rb
+++ b/spec/ruby/core/hash/shared/iteration.rb
@@ -5,15 +5,15 @@ describe :hash_iteration_no_block, shared: true do
   end
 
   it "returns an Enumerator if called on a non-empty hash without a block" do
-    @hsh.send(@method).should be_an_instance_of(Enumerator)
+    @hsh.send(@method).should.instance_of?(Enumerator)
   end
 
   it "returns an Enumerator if called on an empty hash without a block" do
-    @empty.send(@method).should be_an_instance_of(Enumerator)
+    @empty.send(@method).should.instance_of?(Enumerator)
   end
 
   it "returns an Enumerator if called on a frozen instance" do
     @hsh.freeze
-    @hsh.send(@method).should be_an_instance_of(Enumerator)
+    @hsh.send(@method).should.instance_of?(Enumerator)
   end
 end
diff --git a/spec/ruby/core/hash/shared/key.rb b/spec/ruby/core/hash/shared/key.rb
deleted file mode 100644
index 17f9f81457..0000000000
--- a/spec/ruby/core/hash/shared/key.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-describe :hash_key_p, shared: true do
-  it "returns true if argument is a key" do
-    h = { a: 1, b: 2, c: 3, 4 => 0 }
-    h.send(@method, :a).should == true
-    h.send(@method, :b).should == true
-    h.send(@method, 2).should == false
-    h.send(@method, 4).should == true
-
-    not_supported_on :opal do
-      h.send(@method, 'b').should == false
-      h.send(@method, 4.0).should == false
-    end
-  end
-
-  it "returns true if the key's matching value was nil" do
-    { xyz: nil }.send(@method, :xyz).should == true
-  end
-
-  it "returns true if the key's matching value was false" do
-    { xyz: false }.send(@method, :xyz).should == true
-  end
-
-  it "returns true if the key is nil" do
-    { nil => 'b' }.send(@method, nil).should == true
-    { nil => nil }.send(@method, nil).should == true
-  end
-
-  it "compares keys with the same #hash value via #eql?" do
-    x = mock('x')
-    x.stub!(:hash).and_return(42)
-
-    y = mock('y')
-    y.stub!(:hash).and_return(42)
-    y.should_receive(:eql?).and_return(false)
-
-    { x => nil }.send(@method, y).should == false
-  end
-end
diff --git a/spec/ruby/core/hash/shared/length.rb b/spec/ruby/core/hash/shared/length.rb
deleted file mode 100644
index 24f5563759..0000000000
--- a/spec/ruby/core/hash/shared/length.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-describe :hash_length, shared: true do
-  it "returns the number of entries" do
-    { a: 1, b: 'c' }.send(@method).should == 2
-    h = { a: 1, b: 2 }
-    h[:a] = 2
-    h.send(@method).should == 2
-    { a: 1, b: 1, c: 1 }.send(@method).should == 3
-    {}.send(@method).should == 0
-    Hash.new(5).send(@method).should == 0
-    Hash.new { 5 }.send(@method).should == 0
-  end
-end
diff --git a/spec/ruby/core/hash/shared/less_than.rb b/spec/ruby/core/hash/shared/less_than.rb
index cdc6f14546..071b3e97bb 100644
--- a/spec/ruby/core/hash/shared/less_than.rb
+++ b/spec/ruby/core/hash/shared/less_than.rb
@@ -5,11 +5,11 @@ describe :hash_less_than, shared: true do
   end
 
   it "returns true if self is a subset of the other hash" do
-    @h1.send(@method, @h2).should be_true
+    @h1.send(@method, @h2).should == true
   end
 
   it "returns false if self is not a subset of the other hash" do
-    @h2.send(@method, @h1).should be_false
+    @h2.send(@method, @h1).should == false
   end
 
   it "converts the right operand to a hash before comparing" do
@@ -18,6 +18,6 @@ describe :hash_less_than, shared: true do
       { a: 1, b: 2, c: 3 }
     end
 
-    @h1.send(@method, o).should be_true
+    @h1.send(@method, o).should == true
   end
 end
diff --git a/spec/ruby/core/hash/shared/replace.rb b/spec/ruby/core/hash/shared/replace.rb
deleted file mode 100644
index b3d098763b..0000000000
--- a/spec/ruby/core/hash/shared/replace.rb
+++ /dev/null
@@ -1,51 +0,0 @@
-describe :hash_replace, shared: true do
-  it "replaces the contents of self with other" do
-    h = { a: 1, b: 2 }
-    h.send(@method, c: -1, d: -2).should equal(h)
-    h.should == { c: -1, d: -2 }
-  end
-
-  it "tries to convert the passed argument to a hash using #to_hash" do
-    obj = mock('{1=>2,3=>4}')
-    obj.should_receive(:to_hash).and_return({ 1 => 2, 3 => 4 })
-
-    h = {}
-    h.send(@method, obj)
-    h.should == { 1 => 2, 3 => 4 }
-  end
-
-  it "calls to_hash on hash subclasses" do
-    h = {}
-    h.send(@method, HashSpecs::ToHashHash[1 => 2])
-    h.should == { 1 => 2 }
-  end
-
-  it "does not transfer default values" do
-    hash_a = {}
-    hash_b = Hash.new(5)
-    hash_a.send(@method, hash_b)
-    hash_a.default.should == 5
-
-    hash_a = {}
-    hash_b = Hash.new { |h, k| k * 2 }
-    hash_a.send(@method, hash_b)
-    hash_a.default(5).should == 10
-
-    hash_a = Hash.new { |h, k| k * 5 }
-    hash_b = Hash.new(-> { raise "Should not invoke lambda" })
-    hash_a.send(@method, hash_b)
-    hash_a.default.should == hash_b.default
-  end
-
-  it "raises a #{frozen_error_class} if called on a frozen instance that would not be modified" do
-    -> do
-      HashSpecs.frozen_hash.send(@method, HashSpecs.frozen_hash)
-    end.should raise_error(frozen_error_class)
-  end
-
-  it "raises a #{frozen_error_class} if called on a frozen instance that is modified" do
-    -> do
-      HashSpecs.frozen_hash.send(@method, HashSpecs.empty_frozen_hash)
-    end.should raise_error(frozen_error_class)
-  end
-end
diff --git a/spec/ruby/core/hash/shared/select.rb b/spec/ruby/core/hash/shared/select.rb
deleted file mode 100644
index bb781817cb..0000000000
--- a/spec/ruby/core/hash/shared/select.rb
+++ /dev/null
@@ -1,91 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../fixtures/classes'
-require_relative '../shared/iteration'
-require_relative '../../enumerable/shared/enumeratorized'
-
-describe :hash_select, shared: true do
-  before :each do
-    @hsh = { 1 => 2, 3 => 4, 5 => 6 }
-    @empty = {}
-  end
-
-  it "yields two arguments: key and value" do
-    all_args = []
-    { 1 => 2, 3 => 4 }.send(@method) { |*args| all_args << args }
-    all_args.sort.should == [[1, 2], [3, 4]]
-  end
-
-  it "returns a Hash of entries for which block is true" do
-    a_pairs = { 'a' => 9, 'c' => 4, 'b' => 5, 'd' => 2 }.send(@method) { |k,v| v % 2 == 0 }
-    a_pairs.should be_an_instance_of(Hash)
-    a_pairs.sort.should == [['c', 4], ['d', 2]]
-  end
-
-  it "processes entries with the same order as reject" do
-    h = { a: 9, c: 4, b: 5, d: 2 }
-
-    select_pairs = []
-    reject_pairs = []
-    h.dup.send(@method) { |*pair| select_pairs << pair }
-    h.reject { |*pair| reject_pairs << pair }
-
-    select_pairs.should == reject_pairs
-  end
-
-  it "returns an Enumerator when called on a non-empty hash without a block" do
-    @hsh.send(@method).should be_an_instance_of(Enumerator)
-  end
-
-  it "returns an Enumerator when called on an empty hash without a block" do
-    @empty.send(@method).should be_an_instance_of(Enumerator)
-  end
-
-  it_should_behave_like :hash_iteration_no_block
-
-  before :each do
-    @object = { 1 => 2, 3 => 4, 5 => 6 }
-  end
-  it_should_behave_like :enumeratorized_with_origin_size
-end
-
-describe :hash_select!, shared: true do
-  before :each do
-    @hsh = { 1 => 2, 3 => 4, 5 => 6 }
-    @empty = {}
-  end
-
-  it "is equivalent to keep_if if changes are made" do
-    h = { a: 2 }
-    h.send(@method) { |k,v| v <= 1 }.should equal h
-
-    h = { 1 => 2, 3 => 4 }
-    all_args_select = []
-    h.dup.send(@method) { |*args| all_args_select << args }
-    all_args_select.should == [[1, 2], [3, 4]]
-  end
-
-  it "removes all entries if the block is false" do
-    h = { a: 1, b: 2, c: 3 }
-    h.send(@method) { |k,v| false }.should equal(h)
-    h.should == {}
-  end
-
-  it "returns nil if no changes were made" do
-    { a: 1 }.send(@method) { |k,v| v <= 1 }.should == nil
-  end
-
-  it "raises a #{frozen_error_class} if called on an empty frozen instance" do
-    -> { HashSpecs.empty_frozen_hash.send(@method) { false } }.should raise_error(frozen_error_class)
-  end
-
-  it "raises a #{frozen_error_class} if called on a frozen instance that would not be modified" do
-    -> { HashSpecs.frozen_hash.send(@method) { true } }.should raise_error(frozen_error_class)
-  end
-
-  it_should_behave_like :hash_iteration_no_block
-
-  before :each do
-    @object = { 1 => 2, 3 => 4, 5 => 6 }
-  end
-  it_should_behave_like :enumeratorized_with_origin_size
-end
diff --git a/spec/ruby/core/hash/shared/store.rb b/spec/ruby/core/hash/shared/store.rb
deleted file mode 100644
index ff40bef3ef..0000000000
--- a/spec/ruby/core/hash/shared/store.rb
+++ /dev/null
@@ -1,98 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :hash_store, shared: true do
-  it "associates the key with the value and return the value" do
-    h = { a: 1 }
-    h.send(@method, :b, 2).should == 2
-    h.should == { b:2, a:1 }
-  end
-
-  it "duplicates string keys using dup semantics" do
-    # dup doesn't copy singleton methods
-    key = "foo"
-    def key.reverse() "bar" end
-    h = {}
-    h.send(@method, key, 0)
-    h.keys[0].reverse.should == "oof"
-  end
-
-  it "stores unequal keys that hash to the same value" do
-    h = {}
-    k1 = ["x"]
-    k2 = ["y"]
-    # So they end up in the same bucket
-    k1.should_receive(:hash).and_return(0)
-    k2.should_receive(:hash).and_return(0)
-
-    h.send(@method, k1, 1)
-    h.send(@method, k2, 2)
-    h.size.should == 2
-  end
-
-  it "accepts keys with private #hash method" do
-    key = HashSpecs::KeyWithPrivateHash.new
-    h = {}
-    h.send(@method, key, "foo")
-    h[key].should == "foo"
-  end
-
-  it " accepts keys with a Bignum hash" do
-    o = mock(hash: 1 << 100)
-    h = {}
-    h[o] = 1
-    h[o].should == 1
-  end
-
-  it "duplicates and freezes string keys" do
-    key = "foo"
-    h = {}
-    h.send(@method, key, 0)
-    key << "bar"
-
-    h.should == { "foo" => 0 }
-    h.keys[0].frozen?.should == true
-  end
-
-  it "doesn't duplicate and freeze already frozen string keys" do
-    key = "foo".freeze
-    h = {}
-    h.send(@method, key, 0)
-    h.keys[0].should equal(key)
-  end
-
-  it "keeps the existing key in the hash if there is a matching one" do
-    h = { "a" => 1, "b" => 2, "c" => 3, "d" => 4 }
-    key1 = HashSpecs::ByValueKey.new(13)
-    key2 = HashSpecs::ByValueKey.new(13)
-    h[key1] = 41
-    key_in_hash = h.keys.last
-    key_in_hash.should equal(key1)
-    h[key2] = 42
-    last_key = h.keys.last
-    last_key.should equal(key_in_hash)
-    last_key.should_not equal(key2)
-  end
-
-  it "keeps the existing String key in the hash if there is a matching one" do
-    h = { "a" => 1, "b" => 2, "c" => 3, "d" => 4 }
-    key1 = "foo"
-    key2 = "foo"
-    key1.should_not equal(key2)
-    h[key1] = 41
-    frozen_key = h.keys.last
-    frozen_key.should_not equal(key1)
-    h[key2] = 42
-    h.keys.last.should equal(frozen_key)
-    h.keys.last.should_not equal(key2)
-  end
-
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.send(@method, 1, 2) }.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an exception if changing the value of an existing key during iteration" do
-      hash = {1 => 2, 3 => 4, 5 => 6}
-      hash.each { hash.send(@method, 1, :foo) }
-      hash.should == {1 => :foo, 3 => 4, 5 => 6}
-  end
-end
diff --git a/spec/ruby/core/hash/shared/to_s.rb b/spec/ruby/core/hash/shared/to_s.rb
deleted file mode 100644
index d180d08c2c..0000000000
--- a/spec/ruby/core/hash/shared/to_s.rb
+++ /dev/null
@@ -1,96 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../fixtures/classes'
-
-describe :hash_to_s, shared: true do
-
-  it "returns a string representation with same order as each()" do
-    h = { a: [1, 2], b: -2, d: -6, nil => nil }
-
-    pairs = []
-    h.each do |key, value|
-      pairs << key.inspect + '=>' + value.inspect
-    end
-
-    str = '{' + pairs.join(', ') + '}'
-    h.send(@method).should == str
-  end
-
-  it "calls #inspect on keys and values" do
-    key = mock('key')
-    val = mock('val')
-    key.should_receive(:inspect).and_return('key')
-    val.should_receive(:inspect).and_return('val')
-
-    { key => val }.send(@method).should == '{key=>val}'
-  end
-
-  it "does not call #to_s on a String returned from #inspect" do
-    str = "abc"
-    str.should_not_receive(:to_s)
-
-    { a: str }.send(@method).should == '{:a=>"abc"}'
-  end
-
-  it "calls #to_s on the object returned from #inspect if the Object isn't a String" do
-    obj = mock("Hash#inspect/to_s calls #to_s")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_return("abc")
-
-    { a: obj }.send(@method).should == "{:a=>abc}"
-  end
-
-  it "does not call #to_str on the object returned from #inspect when it is not a String" do
-    obj = mock("Hash#inspect/to_s does not call #to_str")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_not_receive(:to_str)
-
-    { a: obj }.send(@method).should =~ /^\{:a=>#<MockObject:0x[0-9a-f]+>\}$/
-  end
-
-  it "does not call #to_str on the object returned from #to_s when it is not a String" do
-    obj = mock("Hash#inspect/to_s does not call #to_str on #to_s result")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_return(obj)
-    obj.should_not_receive(:to_str)
-
-    { a: obj }.send(@method).should =~ /^\{:a=>#<MockObject:0x[0-9a-f]+>\}$/
-  end
-
-  it "does not swallow exceptions raised by #to_s" do
-    obj = mock("Hash#inspect/to_s does not swallow #to_s exceptions")
-    obj.should_receive(:inspect).and_return(obj)
-    obj.should_receive(:to_s).and_raise(Exception)
-
-    -> { { a: obj }.send(@method) }.should raise_error(Exception)
-  end
-
-  it "handles hashes with recursive values" do
-    x = {}
-    x[0] = x
-    x.send(@method).should == '{0=>{...}}'
-
-    x = {}
-    y = {}
-    x[0] = y
-    y[1] = x
-    x.send(@method).should == "{0=>{1=>{...}}}"
-    y.send(@method).should == "{1=>{0=>{...}}}"
-  end
-
-  it "returns a tainted string if self is tainted and not empty" do
-    {}.taint.send(@method).tainted?.should be_false
-    { nil => nil }.taint.send(@method).tainted?.should be_true
-  end
-
-  it "returns an untrusted string if self is untrusted and not empty" do
-    {}.untrust.send(@method).untrusted?.should be_false
-    { nil => nil }.untrust.send(@method).untrusted?.should be_true
-  end
-
-  it "does not raise if inspected result is not default external encoding" do
-    utf_16be = mock("utf_16be")
-    utf_16be.should_receive(:inspect).and_return(%<"utf_16be \u3042">.encode!(Encoding::UTF_16BE))
-
-    {a: utf_16be}.send(@method).should == '{:a=>"utf_16be \u3042"}'
-  end
-end
diff --git a/spec/ruby/core/hash/shared/update.rb b/spec/ruby/core/hash/shared/update.rb
deleted file mode 100644
index 3af41c450a..0000000000
--- a/spec/ruby/core/hash/shared/update.rb
+++ /dev/null
@@ -1,78 +0,0 @@
-describe :hash_update, shared: true do
-  it "adds the entries from other, overwriting duplicate keys. Returns self" do
-    h = { _1: 'a', _2: '3' }
-    h.send(@method, _1: '9', _9: 2).should equal(h)
-    h.should == { _1: "9", _2: "3", _9: 2 }
-  end
-
-  it "sets any duplicate key to the value of block if passed a block" do
-    h1 = { a: 2, b: -1 }
-    h2 = { a: -2, c: 1 }
-    h1.send(@method, h2) { |k,x,y| 3.14 }.should equal(h1)
-    h1.should == { c: 1, b: -1, a: 3.14 }
-
-    h1.send(@method, h1) { nil }
-    h1.should == { a: nil, b: nil, c: nil }
-  end
-
-  it "tries to convert the passed argument to a hash using #to_hash" do
-    obj = mock('{1=>2}')
-    obj.should_receive(:to_hash).and_return({ 1 => 2 })
-    { 3 => 4 }.send(@method, obj).should == { 1 => 2, 3 => 4 }
-  end
-
-  it "does not call to_hash on hash subclasses" do
-    { 3 => 4 }.send(@method, HashSpecs::ToHashHash[1 => 2]).should == { 1 => 2, 3 => 4 }
-  end
-
-  it "processes entries with same order as merge()" do
-    h = { 1 => 2, 3 => 4, 5 => 6, "x" => nil, nil => 5, [] => [] }
-    merge_bang_pairs = []
-    merge_pairs = []
-    h.merge(h) { |*arg| merge_pairs << arg }
-    h.send(@method, h) { |*arg| merge_bang_pairs << arg }
-    merge_bang_pairs.should == merge_pairs
-  end
-
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> do
-      HashSpecs.frozen_hash.send(@method, 1 => 2)
-    end.should raise_error(frozen_error_class)
-  end
-
-  it "checks frozen status before coercing an object with #to_hash" do
-    obj = mock("to_hash frozen")
-    # This is necessary because mock cleanup code cannot run on the frozen
-    # object.
-    def obj.to_hash() raise Exception, "should not receive #to_hash" end
-    obj.freeze
-
-    -> { HashSpecs.frozen_hash.send(@method, obj) }.should raise_error(frozen_error_class)
-  end
-
-  # see redmine #1571
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> do
-      HashSpecs.frozen_hash.send(@method, HashSpecs.empty_frozen_hash)
-    end.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an exception if changing the value of an existing key during iteration" do
-    hash = {1 => 2, 3 => 4, 5 => 6}
-    hash2 = {1 => :foo, 3 => :bar}
-    hash.each { hash.send(@method, hash2) }
-    hash.should == {1 => :foo, 3 => :bar, 5 => 6}
-  end
-
-  ruby_version_is "2.6" do
-    it "accepts multiple hashes" do
-      result = { a: 1 }.send(@method, { b: 2 }, { c: 3 }, { d: 4 })
-      result.should == { a: 1, b: 2, c: 3, d: 4 }
-    end
-
-    it "accepts zero arguments" do
-      hash = { a: 1 }
-      hash.send(@method).should eql(hash)
-    end
-  end
-end
diff --git a/spec/ruby/core/hash/shared/value.rb b/spec/ruby/core/hash/shared/value.rb
deleted file mode 100644
index aac76c253e..0000000000
--- a/spec/ruby/core/hash/shared/value.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-describe :hash_value_p, shared: true do
-  it "returns true if the value exists in the hash" do
-    { a: :b }.send(@method, :a).should == false
-    { 1 => 2 }.send(@method, 2).should == true
-    h = Hash.new(5)
-    h.send(@method, 5).should == false
-    h = Hash.new { 5 }
-    h.send(@method, 5).should == false
-  end
-
-  it "uses == semantics for comparing values" do
-    { 5 => 2.0 }.send(@method, 2).should == true
-  end
-end
diff --git a/spec/ruby/core/hash/shared/values_at.rb b/spec/ruby/core/hash/shared/values_at.rb
deleted file mode 100644
index ef3b0e8ba0..0000000000
--- a/spec/ruby/core/hash/shared/values_at.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-describe :hash_values_at, shared: true do
-  it "returns an array of values for the given keys" do
-    h = { a: 9, b: 'a', c: -10, d: nil }
-    h.send(@method).should be_kind_of(Array)
-    h.send(@method).should == []
-    h.send(@method, :a, :d, :b).should be_kind_of(Array)
-    h.send(@method, :a, :d, :b).should == [9, nil, 'a']
-  end
-end
diff --git a/spec/ruby/core/hash/shift_spec.rb b/spec/ruby/core/hash/shift_spec.rb
index d9f121e38b..6095d2e55f 100644
--- a/spec/ruby/core/hash/shift_spec.rb
+++ b/spec/ruby/core/hash/shift_spec.rb
@@ -8,7 +8,7 @@ describe "Hash#shift" do
 
     h.size.times do |i|
       r = h.shift
-      r.should be_kind_of(Array)
+      r.should.is_a?(Array)
       h2[r.first].should == r.last
       h.size.should == h2.size - i - 1
     end
@@ -30,23 +30,22 @@ describe "Hash#shift" do
     h.should == {}
   end
 
-  it "calls #default with nil if the Hash is empty" do
+  it "returns nil if the Hash is empty" do
     h = {}
     def h.default(key)
-      key.should == nil
-      :foo
+      raise
     end
-    h.shift.should == :foo
+    h.shift.should == nil
   end
 
   it "returns nil from an empty hash" do
     {}.shift.should == nil
   end
 
-  it "returns (computed) default for empty hashes" do
-    Hash.new(5).shift.should == 5
+  it "returns nil for empty hashes with defaults and default procs" do
+    Hash.new(5).shift.should == nil
     h = Hash.new { |*args| args }
-    h.shift.should == [h, nil]
+    h.shift.should == nil
   end
 
   it "preserves Hash invariants when removing the last item" do
@@ -57,9 +56,9 @@ describe "Hash#shift" do
     h.should == {:c => 3}
   end
 
-  it "raises a #{frozen_error_class} if called on a frozen instance" do
-    -> { HashSpecs.frozen_hash.shift  }.should raise_error(frozen_error_class)
-    -> { HashSpecs.empty_frozen_hash.shift }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if called on a frozen instance" do
+    -> { HashSpecs.frozen_hash.shift  }.should.raise(FrozenError)
+    -> { HashSpecs.empty_frozen_hash.shift }.should.raise(FrozenError)
   end
 
   it "works when the hash is at capacity" do
diff --git a/spec/ruby/core/hash/size_spec.rb b/spec/ruby/core/hash/size_spec.rb
index 1e8abd8d97..5e5008a5dc 100644
--- a/spec/ruby/core/hash/size_spec.rb
+++ b/spec/ruby/core/hash/size_spec.rb
@@ -1,7 +1,14 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/length'
 
 describe "Hash#size" do
-  it_behaves_like :hash_length, :size
+  it "returns the number of entries" do
+    { a: 1, b: 'c' }.size.should == 2
+    h = { a: 1, b: 2 }
+    h[:a] = 2
+    h.size.should == 2
+    { a: 1, b: 1, c: 1 }.size.should == 3
+    {}.size.should == 0
+    Hash.new(5).size.should == 0
+    Hash.new { 5 }.size.should == 0
+  end
 end
diff --git a/spec/ruby/core/hash/slice_spec.rb b/spec/ruby/core/hash/slice_spec.rb
index f7717c9404..fd93254517 100644
--- a/spec/ruby/core/hash/slice_spec.rb
+++ b/spec/ruby/core/hash/slice_spec.rb
@@ -1,55 +1,74 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  describe "Hash#slice" do
-    before :each do
-      @hash = { a: 1, b: 2, c: 3 }
-    end
+describe "Hash#slice" do
+  before :each do
+    @hash = { a: 1, b: 2, c: 3 }
+  end
 
-    it "returns a new empty hash without arguments" do
-      ret = @hash.slice
-      ret.should_not equal(@hash)
-      ret.should be_an_instance_of(Hash)
-      ret.should == {}
-    end
+  it "returns a new empty hash without arguments" do
+    ret = @hash.slice
+    ret.should_not.equal?(@hash)
+    ret.should.instance_of?(Hash)
+    ret.should == {}
+  end
 
-    it "returns the requested subset" do
-      @hash.slice(:c, :a).should == { c: 3, a: 1 }
-    end
+  it "returns the requested subset" do
+    @hash.slice(:c, :a).should == { c: 3, a: 1 }
+  end
 
-    it "returns a hash ordered in the order of the requested keys" do
-      @hash.slice(:c, :a).keys.should == [:c, :a]
-    end
+  it "returns a hash ordered in the order of the requested keys" do
+    @hash.slice(:c, :a).keys.should == [:c, :a]
+  end
 
-    it "returns only the keys of the original hash" do
-      @hash.slice(:a, :chunky_bacon).should == { a: 1 }
-    end
+  it "returns only the keys of the original hash" do
+    @hash.slice(:a, :chunky_bacon).should == { a: 1 }
+  end
 
-    it "returns a Hash instance, even on subclasses" do
-      klass = Class.new(Hash)
-      h = klass.new
-      h[:bar] = 12
-      h[:foo] = 42
-      r = h.slice(:foo)
-      r.should == {foo: 42}
-      r.class.should == Hash
-    end
+  it "returns a Hash instance, even on subclasses" do
+    klass = Class.new(Hash)
+    h = klass.new
+    h[:bar] = 12
+    h[:foo] = 42
+    r = h.slice(:foo)
+    r.should == {foo: 42}
+    r.class.should == Hash
+  end
 
-    it "uses the regular Hash#[] method, even on subclasses that override it" do
-      ScratchPad.record []
-      klass = Class.new(Hash) do
-        def [](value)
-          ScratchPad << :used_subclassed_operator
-          super
-        end
+  it "uses the regular Hash#[] method, even on subclasses that override it" do
+    ScratchPad.record []
+    klass = Class.new(Hash) do
+      def [](value)
+        ScratchPad << :used_subclassed_operator
+        super
       end
+    end
 
-      h = klass.new
-      h[:bar] = 12
-      h[:foo] = 42
-      h.slice(:foo)
+    h = klass.new
+    h[:bar] = 12
+    h[:foo] = 42
+    h.slice(:foo)
 
-      ScratchPad.recorded.should == []
-    end
+    ScratchPad.recorded.should == []
+  end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.slice(:a).default.should == nil
+    h[:a] = 1
+    h.slice(:a).default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.slice(:a).default_proc.should == nil
+    h[:a] = 1
+    h.slice(:a).default_proc.should == nil
+  end
+
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.slice(:a)
+    h2.compare_by_identity?.should == true
   end
 end
diff --git a/spec/ruby/core/hash/store_spec.rb b/spec/ruby/core/hash/store_spec.rb
index 7e975380ec..7017d8ba2b 100644
--- a/spec/ruby/core/hash/store_spec.rb
+++ b/spec/ruby/core/hash/store_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/store'
 
 describe "Hash#store" do
-  it_behaves_like :hash_store, :store
+  it "is an alias of Hash#[]=" do
+    Hash.instance_method(:store).should == Hash.instance_method(:[]=)
+  end
 end
diff --git a/spec/ruby/core/hash/to_a_spec.rb b/spec/ruby/core/hash/to_a_spec.rb
index 33ad7cdec9..8c638db6c3 100644
--- a/spec/ruby/core/hash/to_a_spec.rb
+++ b/spec/ruby/core/hash/to_a_spec.rb
@@ -10,7 +10,7 @@ describe "Hash#to_a" do
       pairs << [key, value]
     end
 
-    h.to_a.should be_kind_of(Array)
+    h.to_a.should.is_a?(Array)
     h.to_a.should == pairs
   end
 
@@ -23,15 +23,7 @@ describe "Hash#to_a" do
     end
 
     ent = h.entries
-    ent.should be_kind_of(Array)
+    ent.should.is_a?(Array)
     ent.should == pairs
   end
-
-  it "returns a tainted array if self is tainted" do
-    {}.taint.to_a.tainted?.should be_true
-  end
-
-  it "returns an untrusted array if self is untrusted" do
-    {}.untrust.to_a.untrusted?.should be_true
-  end
 end
diff --git a/spec/ruby/core/hash/to_h_spec.rb b/spec/ruby/core/hash/to_h_spec.rb
index d6eaac9f33..5d5a280dac 100644
--- a/spec/ruby/core/hash/to_h_spec.rb
+++ b/spec/ruby/core/hash/to_h_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Hash#to_h" do
   it "returns self for Hash instances" do
     h = {}
-    h.to_h.should equal(h)
+    h.to_h.should.equal?(h)
   end
 
   describe "when called on a subclass of Hash" do
@@ -14,61 +14,93 @@ describe "Hash#to_h" do
     end
 
     it "returns a new Hash instance" do
-      @h.to_h.should be_an_instance_of(Hash)
+      @h.to_h.should.instance_of?(Hash)
       @h.to_h.should == @h
       @h[:foo].should == :bar
     end
 
-    it "copies the default" do
+    it "retains the default" do
       @h.default = 42
       @h.to_h.default.should == 42
       @h[:hello].should == 42
     end
 
-    it "copies the default_proc" do
+    it "retains the default_proc" do
       @h.default_proc = prc = Proc.new{ |h, k| h[k] = 2 * k }
       @h.to_h.default_proc.should == prc
       @h[42].should == 84
     end
+
+    it "retains compare_by_identity flag" do
+      @h.compare_by_identity
+      @h.to_h.compare_by_identity?.should == true
+    end
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v]}.should == { "a" => 1, "b" => 4 }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        { a: 1 }.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          { a: 1 }.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v]}.should == { "a" => 1, "b" => 4 }
+    end
+
+    it "passes to a block each pair's key and value as separate arguments" do
+      ScratchPad.record []
+      { a: 1, b: 2 }.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [[:a, 1], [:b, 2]]
+
+      ScratchPad.record []
+      { a: 1, b: 2 }.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[:a, 1], [:b, 2]]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      { a: 1 }.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        { a: 1 }.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
+    end
+
+    it "does not retain the default value" do
+      h = Hash.new(1)
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.default.should == nil
+    end
+
+    it "does not retain the default_proc" do
+      pr = proc { |h, k| h[k] = [] }
+      h = Hash.new(&pr)
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.default_proc.should == nil
+    end
+
+    it "does not retain compare_by_identity flag" do
+      h = { a: 9, c: 4 }.compare_by_identity
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.compare_by_identity?.should == false
     end
   end
 end
diff --git a/spec/ruby/core/hash/to_hash_spec.rb b/spec/ruby/core/hash/to_hash_spec.rb
index f479fa1fb2..f5622b3d9c 100644
--- a/spec/ruby/core/hash/to_hash_spec.rb
+++ b/spec/ruby/core/hash/to_hash_spec.rb
@@ -4,11 +4,11 @@ require_relative 'fixtures/classes'
 describe "Hash#to_hash" do
   it "returns self for Hash instances" do
     h = {}
-    h.to_hash.should equal(h)
+    h.to_hash.should.equal?(h)
   end
 
   it "returns self for instances of subclasses of Hash" do
     h = HashSpecs::MyHash.new
-    h.to_hash.should equal(h)
+    h.to_hash.should.equal?(h)
   end
 end
diff --git a/spec/ruby/core/hash/to_proc_spec.rb b/spec/ruby/core/hash/to_proc_spec.rb
index 3e7e57d11f..bc4756600d 100644
--- a/spec/ruby/core/hash/to_proc_spec.rb
+++ b/spec/ruby/core/hash/to_proc_spec.rb
@@ -11,7 +11,7 @@ describe "Hash#to_proc" do
   end
 
   it "returns an instance of Proc" do
-    @hash.to_proc.should be_an_instance_of Proc
+    @hash.to_proc.should.instance_of? Proc
   end
 
   describe "the returned proc" do
@@ -19,29 +19,33 @@ describe "Hash#to_proc" do
       @proc = @hash.to_proc
     end
 
-    it "is not a lambda" do
-      @proc.lambda?.should == false
+    it "is a lambda" do
+      @proc.should.lambda?
+    end
+
+    it "has an arity of 1" do
+      @proc.arity.should == 1
     end
 
     it "raises ArgumentError if not passed exactly one argument" do
       -> {
         @proc.call
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
 
       -> {
         @proc.call 1, 2
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
 
     context "with a stored key" do
       it "returns the paired value" do
-        @proc.call(@key).should equal(@value)
+        @proc.call(@key).should.equal?(@value)
       end
     end
 
     context "passed as a block" do
       it "retrieves the hash's values" do
-        [@key].map(&@proc)[0].should equal(@value)
+        [@key].map(&@proc)[0].should.equal?(@value)
       end
 
       context "to instance_exec" do
@@ -59,7 +63,7 @@ describe "Hash#to_proc" do
 
     context "with no stored key" do
       it "returns nil" do
-        @proc.call(@unstored).should be_nil
+        @proc.call(@unstored).should == nil
       end
 
       context "when the hash has a default value" do
@@ -68,7 +72,7 @@ describe "Hash#to_proc" do
         end
 
         it "returns the default value" do
-          @proc.call(@unstored).should equal(@default)
+          @proc.call(@unstored).should.equal?(@default)
         end
       end
 
@@ -81,7 +85,7 @@ describe "Hash#to_proc" do
     end
 
     it "raises an ArgumentError when calling #call on the Proc with no arguments" do
-      -> { @hash.to_proc.call }.should raise_error(ArgumentError)
+      -> { @hash.to_proc.call }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/hash/to_s_spec.rb b/spec/ruby/core/hash/to_s_spec.rb
index e52b09962e..2915db6ef8 100644
--- a/spec/ruby/core/hash/to_s_spec.rb
+++ b/spec/ruby/core/hash/to_s_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/to_s'
 
 describe "Hash#to_s" do
-  it_behaves_like :hash_to_s, :to_s
+  it "is an alias of Hash#inspect" do
+    Hash.instance_method(:to_s).should == Hash.instance_method(:inspect)
+  end
 end
diff --git a/spec/ruby/core/hash/transform_keys_spec.rb b/spec/ruby/core/hash/transform_keys_spec.rb
index 32ac89b765..d37a2b8616 100644
--- a/spec/ruby/core/hash/transform_keys_spec.rb
+++ b/spec/ruby/core/hash/transform_keys_spec.rb
@@ -1,131 +1,149 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  describe "Hash#transform_keys" do
-    before :each do
-      @hash = { a: 1, b: 2, c: 3 }
-    end
+describe "Hash#transform_keys" do
+  before :each do
+    @hash = { a: 1, b: 2, c: 3 }
+  end
 
-    it "returns new hash" do
-      ret = @hash.transform_keys(&:succ)
-      ret.should_not equal(@hash)
-      ret.should be_an_instance_of(Hash)
-    end
+  it "returns new hash" do
+    ret = @hash.transform_keys(&:succ)
+    ret.should_not.equal?(@hash)
+    ret.should.instance_of?(Hash)
+  end
 
-    it "sets the result as transformed keys with the given block" do
-      @hash.transform_keys(&:succ).should ==  { b: 1, c: 2, d: 3 }
-    end
+  it "sets the result as transformed keys with the given block" do
+    @hash.transform_keys(&:succ).should ==  { b: 1, c: 2, d: 3 }
+  end
 
-    it "keeps last pair if new keys conflict" do
-      @hash.transform_keys { |_| :a }.should == { a: 3 }
-    end
+  it "keeps last pair if new keys conflict" do
+    @hash.transform_keys { |_| :a }.should == { a: 3 }
+  end
 
-    it "makes both hashes to share values" do
-      value = [1, 2, 3]
-      new_hash = { a: value }.transform_keys(&:upcase)
-      new_hash[:A].should equal(value)
-    end
+  it "makes both hashes to share values" do
+    value = [1, 2, 3]
+    new_hash = { a: value }.transform_keys(&:upcase)
+    new_hash[:A].should.equal?(value)
+  end
 
-    context "when no block is given" do
-      it "returns a sized Enumerator" do
-        enumerator = @hash.transform_keys
-        enumerator.should be_an_instance_of(Enumerator)
-        enumerator.size.should == @hash.size
-        enumerator.each(&:succ).should == { b: 1, c: 2, d: 3 }
-      end
+  context "when no block is given" do
+    it "returns a sized Enumerator" do
+      enumerator = @hash.transform_keys
+      enumerator.should.instance_of?(Enumerator)
+      enumerator.size.should == @hash.size
+      enumerator.each(&:succ).should == { b: 1, c: 2, d: 3 }
     end
+  end
 
-    it "returns a Hash instance, even on subclasses" do
-      klass = Class.new(Hash)
-      h = klass.new
-      h[:foo] = 42
-      r = h.transform_keys{|v| :"x#{v}"}
-      r.keys.should == [:xfoo]
-      r.class.should == Hash
-    end
+  it "returns a Hash instance, even on subclasses" do
+    klass = Class.new(Hash)
+    h = klass.new
+    h[:foo] = 42
+    r = h.transform_keys{|v| :"x#{v}"}
+    r.keys.should == [:xfoo]
+    r.class.should == Hash
   end
 
-  describe "Hash#transform_keys!" do
-    before :each do
-      @hash = { a: 1, b: 2, c: 3, d: 4 }
-      @initial_pairs = @hash.dup
-    end
+  it "allows a hash argument" do
+    @hash.transform_keys({ a: :A, b: :B, c: :C }).should == { A: 1, B: 2, C: 3 }
+  end
 
-    it "returns self" do
-      @hash.transform_keys!(&:succ).should equal(@hash)
-    end
+  it "allows a partial transformation of keys when using a hash argument" do
+    @hash.transform_keys({ a: :A, c: :C }).should == { A: 1, b: 2, C: 3 }
+  end
 
-    it "updates self as transformed values with the given block" do
-      @hash.transform_keys!(&:to_s)
-      @hash.should == { 'a' => 1, 'b' => 2, 'c' => 3, 'd' => 4 }
-    end
+  it "allows a combination of hash and block argument" do
+    @hash.transform_keys({ a: :A }, &:to_s).should == { A: 1, 'b' => 2, 'c' => 3 }
+  end
 
-    # https://bugs.ruby-lang.org/issues/14380
-    ruby_version_is ""..."2.5.1" do
-      it "does not prevent conflicts between new keys and old ones" do
-        @hash.transform_keys!(&:succ)
-        @hash.should == { e: 1 }
-      end
-    end
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.transform_keys(&:succ).default.should == nil
+    h[:a] = 1
+    h.transform_keys(&:succ).default.should == nil
+  end
 
-    ruby_version_is "2.5.1" do
-      it "prevents conflicts between new keys and old ones" do
-        @hash.transform_keys!(&:succ)
-        @hash.should == { b: 1, c: 2, d: 3, e: 4 }
-      end
-    end
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.transform_values(&:succ).default_proc.should == nil
+    h[:a] = 1
+    h.transform_values(&:succ).default_proc.should == nil
+  end
 
-    ruby_version_is ""..."2.5.1" do
-      it "partially modifies the contents if we broke from the block" do
-        @hash.transform_keys! do |v|
-          break if v == :c
-          v.succ
-        end
-        @hash.should == { c: 1, d: 4 }
-      end
-    end
+  it "does not retain compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.transform_keys(&:succ)
+    h2.compare_by_identity?.should == false
+  end
+end
 
-    ruby_version_is "2.5.1" do
-      it "returns the processed keys if we broke from the block" do
-        @hash.transform_keys! do |v|
-          break if v == :c
-          v.succ
-        end
-        @hash.should == { b: 1, c: 2 }
-      end
+describe "Hash#transform_keys!" do
+  before :each do
+    @hash = { a: 1, b: 2, c: 3, d: 4 }
+    @initial_pairs = @hash.dup
+  end
+
+  it "returns self" do
+    @hash.transform_keys!(&:succ).should.equal?(@hash)
+  end
+
+  it "updates self as transformed values with the given block" do
+    @hash.transform_keys!(&:to_s)
+    @hash.should == { 'a' => 1, 'b' => 2, 'c' => 3, 'd' => 4 }
+  end
+
+  it "prevents conflicts between new keys and old ones" do
+    @hash.transform_keys!(&:succ)
+    @hash.should == { b: 1, c: 2, d: 3, e: 4 }
+  end
+
+  it "returns the processed keys and non evaluated keys if we break from the block" do
+    @hash.transform_keys! do |v|
+      break if v == :c
+      v.succ
     end
+    @hash.should == { b: 1, c: 2, d: 4 }
+  end
+
+  it "keeps later pair if new keys conflict" do
+    @hash.transform_keys! { |_| :a }.should == { a: 4 }
+  end
 
-    it "keeps later pair if new keys conflict" do
-      @hash.transform_keys! { |_| :a }.should == { a: 4 }
+  context "when no block is given" do
+    it "returns a sized Enumerator" do
+      enumerator = @hash.transform_keys!
+      enumerator.should.instance_of?(Enumerator)
+      enumerator.size.should == @hash.size
+      enumerator.each(&:upcase).should == { A: 1, B: 2, C: 3, D: 4 }
     end
+  end
 
-    context "when no block is given" do
-      it "returns a sized Enumerator" do
-        enumerator = @hash.transform_keys!
-        enumerator.should be_an_instance_of(Enumerator)
-        enumerator.size.should == @hash.size
-        enumerator.each(&:upcase).should == { A: 1, B: 2, C: 3, D: 4 }
-      end
+  it "allows a hash argument" do
+    @hash.transform_keys!({ a: :A, b: :B, c: :C, d: :D })
+    @hash.should == { A: 1, B: 2, C: 3, D: 4 }
+  end
+
+  describe "on frozen instance" do
+    before :each do
+      @hash.freeze
     end
 
-    describe "on frozen instance" do
-      before :each do
-        @hash.freeze
-      end
+    it "raises a FrozenError on an empty hash" do
+      ->{ {}.freeze.transform_keys!(&:upcase) }.should.raise(FrozenError)
+    end
 
-      it "raises a #{frozen_error_class} on an empty hash" do
-        ->{ {}.freeze.transform_keys!(&:upcase) }.should raise_error(frozen_error_class)
-      end
+    it "keeps pairs and raises a FrozenError" do
+      ->{ @hash.transform_keys!(&:upcase) }.should.raise(FrozenError)
+      @hash.should == @initial_pairs
+    end
 
-      it "keeps pairs and raises a #{frozen_error_class}" do
-        ->{ @hash.transform_keys!(&:upcase) }.should raise_error(frozen_error_class)
-        @hash.should == @initial_pairs
-      end
+    it "raises a FrozenError on hash argument" do
+      ->{ @hash.transform_keys!({ a: :A, b: :B, c: :C }) }.should.raise(FrozenError)
+    end
 
-      context "when no block is given" do
-        it "does not raise an exception" do
-          @hash.transform_keys!.should be_an_instance_of(Enumerator)
-        end
+    context "when no block is given" do
+      it "does not raise an exception" do
+        @hash.transform_keys!.should.instance_of?(Enumerator)
       end
     end
   end
diff --git a/spec/ruby/core/hash/transform_values_spec.rb b/spec/ruby/core/hash/transform_values_spec.rb
index 8b53b7a522..b19543a9f4 100644
--- a/spec/ruby/core/hash/transform_values_spec.rb
+++ b/spec/ruby/core/hash/transform_values_spec.rb
@@ -7,8 +7,8 @@ describe "Hash#transform_values" do
 
   it "returns new hash" do
     ret = @hash.transform_values(&:succ)
-    ret.should_not equal(@hash)
-    ret.should be_an_instance_of(Hash)
+    ret.should_not.equal?(@hash)
+    ret.should.instance_of?(Hash)
   end
 
   it "sets the result as transformed values with the given block" do
@@ -19,13 +19,13 @@ describe "Hash#transform_values" do
     key = [1, 2, 3]
     new_hash = { key => 1 }.transform_values(&:succ)
     new_hash[key].should == 2
-    new_hash.keys[0].should equal(key)
+    new_hash.keys[0].should.equal?(key)
   end
 
   context "when no block is given" do
     it "returns a sized Enumerator" do
       enumerator = @hash.transform_values
-      enumerator.should be_an_instance_of(Enumerator)
+      enumerator.should.instance_of?(Enumerator)
       enumerator.size.should == @hash.size
       enumerator.each(&:succ).should == { a: 2, b: 3, c: 4 }
     end
@@ -39,6 +39,27 @@ describe "Hash#transform_values" do
     r[:foo].should == 84
     r.class.should == Hash
   end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.transform_values(&:succ).default.should == nil
+    h[:a] = 1
+    h.transform_values(&:succ).default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.transform_values(&:succ).default_proc.should == nil
+    h[:a] = 1
+    h.transform_values(&:succ).default_proc.should == nil
+  end
+
+  it "retains compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.transform_values(&:succ)
+    h2.compare_by_identity?.should == true
+  end
 end
 
 describe "Hash#transform_values!" do
@@ -48,7 +69,7 @@ describe "Hash#transform_values!" do
   end
 
   it "returns self" do
-    @hash.transform_values!(&:succ).should equal(@hash)
+    @hash.transform_values!(&:succ).should.equal?(@hash)
   end
 
   it "updates self as transformed values with the given block" do
@@ -67,7 +88,7 @@ describe "Hash#transform_values!" do
   context "when no block is given" do
     it "returns a sized Enumerator" do
       enumerator = @hash.transform_values!
-      enumerator.should be_an_instance_of(Enumerator)
+      enumerator.should.instance_of?(Enumerator)
       enumerator.size.should == @hash.size
       enumerator.each(&:succ)
       @hash.should == { a: 2, b: 3, c: 4 }
@@ -79,18 +100,18 @@ describe "Hash#transform_values!" do
       @hash.freeze
     end
 
-    it "raises a #{frozen_error_class} on an empty hash" do
-      ->{ {}.freeze.transform_values!(&:succ) }.should raise_error(frozen_error_class)
+    it "raises a FrozenError on an empty hash" do
+      ->{ {}.freeze.transform_values!(&:succ) }.should.raise(FrozenError)
     end
 
-    it "keeps pairs and raises a #{frozen_error_class}" do
-      ->{ @hash.transform_values!(&:succ) }.should raise_error(frozen_error_class)
+    it "keeps pairs and raises a FrozenError" do
+      ->{ @hash.transform_values!(&:succ) }.should.raise(FrozenError)
       @hash.should == @initial_pairs
     end
 
     context "when no block is given" do
       it "does not raise an exception" do
-        @hash.transform_values!.should be_an_instance_of(Enumerator)
+        @hash.transform_values!.should.instance_of?(Enumerator)
       end
     end
   end
diff --git a/spec/ruby/core/hash/try_convert_spec.rb b/spec/ruby/core/hash/try_convert_spec.rb
index 44195c5010..c321183356 100644
--- a/spec/ruby/core/hash/try_convert_spec.rb
+++ b/spec/ruby/core/hash/try_convert_spec.rb
@@ -4,47 +4,47 @@ require_relative 'fixtures/classes'
 describe "Hash.try_convert" do
   it "returns the argument if it's a Hash" do
     x = Hash.new
-    Hash.try_convert(x).should equal(x)
+    Hash.try_convert(x).should.equal?(x)
   end
 
   it "returns the argument if it's a kind of Hash" do
     x = HashSpecs::MyHash.new
-    Hash.try_convert(x).should equal(x)
+    Hash.try_convert(x).should.equal?(x)
   end
 
   it "returns nil when the argument does not respond to #to_hash" do
-    Hash.try_convert(Object.new).should be_nil
+    Hash.try_convert(Object.new).should == nil
   end
 
   it "sends #to_hash to the argument and returns the result if it's nil" do
     obj = mock("to_hash")
     obj.should_receive(:to_hash).and_return(nil)
-    Hash.try_convert(obj).should be_nil
+    Hash.try_convert(obj).should == nil
   end
 
   it "sends #to_hash to the argument and returns the result if it's a Hash" do
     x = Hash.new
     obj = mock("to_hash")
     obj.should_receive(:to_hash).and_return(x)
-    Hash.try_convert(obj).should equal(x)
+    Hash.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_hash to the argument and returns the result if it's a kind of Hash" do
     x = HashSpecs::MyHash.new
     obj = mock("to_hash")
     obj.should_receive(:to_hash).and_return(x)
-    Hash.try_convert(obj).should equal(x)
+    Hash.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_hash to the argument and raises TypeError if it's not a kind of Hash" do
     obj = mock("to_hash")
     obj.should_receive(:to_hash).and_return(Object.new)
-    -> { Hash.try_convert obj }.should raise_error(TypeError)
+    -> { Hash.try_convert obj }.should raise_consistent_error(TypeError, "can't convert MockObject into Hash (MockObject#to_hash gives Object)")
   end
 
   it "does not rescue exceptions raised by #to_hash" do
     obj = mock("to_hash")
     obj.should_receive(:to_hash).and_raise(RuntimeError)
-    -> { Hash.try_convert obj }.should raise_error(RuntimeError)
+    -> { Hash.try_convert obj }.should.raise(RuntimeError)
   end
 end
diff --git a/spec/ruby/core/hash/update_spec.rb b/spec/ruby/core/hash/update_spec.rb
index 0975045ad1..f3a3e6b4db 100644
--- a/spec/ruby/core/hash/update_spec.rb
+++ b/spec/ruby/core/hash/update_spec.rb
@@ -1,7 +1,79 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/update'
 
 describe "Hash#update" do
-  it_behaves_like :hash_update, :update
+  it "adds the entries from other, overwriting duplicate keys. Returns self" do
+    h = { _1: 'a', _2: '3' }
+    h.update(_1: '9', _9: 2).should.equal?(h)
+    h.should == { _1: "9", _2: "3", _9: 2 }
+  end
+
+  it "sets any duplicate key to the value of block if passed a block" do
+    h1 = { a: 2, b: -1 }
+    h2 = { a: -2, c: 1 }
+    h1.update(h2) { |k,x,y| 3.14 }.should.equal?(h1)
+    h1.should == { c: 1, b: -1, a: 3.14 }
+
+    h1.update(h1) { nil }
+    h1.should == { a: nil, b: nil, c: nil }
+  end
+
+  it "tries to convert the passed argument to a hash using #to_hash" do
+    obj = mock('{1=>2}')
+    obj.should_receive(:to_hash).and_return({ 1 => 2 })
+    { 3 => 4 }.update(obj).should == { 1 => 2, 3 => 4 }
+  end
+
+  it "does not call to_hash on hash subclasses" do
+    { 3 => 4 }.update(HashSpecs::ToHashHash[1 => 2]).should == { 1 => 2, 3 => 4 }
+  end
+
+  it "processes entries with same order as merge()" do
+    h = { 1 => 2, 3 => 4, 5 => 6, "x" => nil, nil => 5, [] => [] }
+    merge_bang_pairs = []
+    merge_pairs = []
+    h.merge(h) { |*arg| merge_pairs << arg }
+    h.update(h) { |*arg| merge_bang_pairs << arg }
+    merge_bang_pairs.should == merge_pairs
+  end
+
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> do
+      HashSpecs.frozen_hash.update(1 => 2)
+    end.should.raise(FrozenError)
+  end
+
+  it "checks frozen status before coercing an object with #to_hash" do
+    obj = mock("to_hash frozen")
+    # This is necessary because mock cleanup code cannot run on the frozen
+    # object.
+    def obj.to_hash() raise Exception, "should not receive #to_hash" end
+    obj.freeze
+
+    -> { HashSpecs.frozen_hash.update(obj) }.should.raise(FrozenError)
+  end
+
+  # see redmine #1571
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> do
+      HashSpecs.frozen_hash.update(HashSpecs.empty_frozen_hash)
+    end.should.raise(FrozenError)
+  end
+
+  it "does not raise an exception if changing the value of an existing key during iteration" do
+    hash = {1 => 2, 3 => 4, 5 => 6}
+    hash2 = {1 => :foo, 3 => :bar}
+    hash.each { hash.update(hash2) }
+    hash.should == {1 => :foo, 3 => :bar, 5 => 6}
+  end
+
+  it "accepts multiple hashes" do
+    result = { a: 1 }.update({ b: 2 }, { c: 3 }, { d: 4 })
+    result.should == { a: 1, b: 2, c: 3, d: 4 }
+  end
+
+  it "accepts zero arguments" do
+    hash = { a: 1 }
+    hash.update.should.eql?(hash)
+  end
 end
diff --git a/spec/ruby/core/hash/value_spec.rb b/spec/ruby/core/hash/value_spec.rb
index 0ab16a5d1b..9cfbe576d2 100644
--- a/spec/ruby/core/hash/value_spec.rb
+++ b/spec/ruby/core/hash/value_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/value'
 
 describe "Hash#value?" do
-  it_behaves_like :hash_value_p, :value?
+  it "is an alias of Hash#has_value?" do
+    Hash.instance_method(:value?).should == Hash.instance_method(:has_value?)
+  end
 end
diff --git a/spec/ruby/core/hash/values_at_spec.rb b/spec/ruby/core/hash/values_at_spec.rb
index b620a279ba..78dcd8df6a 100644
--- a/spec/ruby/core/hash/values_at_spec.rb
+++ b/spec/ruby/core/hash/values_at_spec.rb
@@ -1,7 +1,11 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/values_at'
 
 describe "Hash#values_at" do
-  it_behaves_like :hash_values_at, :values_at
+  it "returns an array of values for the given keys" do
+    h = { a: 9, b: 'a', c: -10, d: nil }
+    h.values_at.should.is_a?(Array)
+    h.values_at.should == []
+    h.values_at(:a, :d, :b).should.is_a?(Array)
+    h.values_at(:a, :d, :b).should == [9, nil, 'a']
+  end
 end
diff --git a/spec/ruby/core/hash/values_spec.rb b/spec/ruby/core/hash/values_spec.rb
index 9f2a481a48..1fe5f48ad6 100644
--- a/spec/ruby/core/hash/values_spec.rb
+++ b/spec/ruby/core/hash/values_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Hash#values" do
   it "returns an array of values" do
     h = { 1 => :a, 'a' => :a, 'the' => 'lang' }
-    h.values.should be_kind_of(Array)
+    h.values.should.is_a?(Array)
     h.values.sort {|a, b| a.to_s <=> b.to_s}.should == [:a, :a, 'lang']
   end
 end
diff --git a/spec/ruby/core/integer/allbits_spec.rb b/spec/ruby/core/integer/allbits_spec.rb
index f4a6fe9905..6023cc32bf 100644
--- a/spec/ruby/core/integer/allbits_spec.rb
+++ b/spec/ruby/core/integer/allbits_spec.rb
@@ -1,39 +1,37 @@
 require_relative '../../spec_helper'
 
-ruby_version_is '2.5' do
-  describe "Integer#allbits?" do
-    it "returns true iff all the bits of the argument are set in the receiver" do
-      42.allbits?(42).should == true
-      0b1010_1010.allbits?(0b1000_0010).should == true
-      0b1010_1010.allbits?(0b1000_0001).should == false
-      0b1000_0010.allbits?(0b1010_1010).should == false
-      (0b1010_1010 | bignum_value).allbits?(0b1000_0010 | bignum_value).should == true
-      (0b1010_1010 | bignum_value).allbits?(0b1000_0001 | bignum_value).should == false
-      (0b1000_0010 | bignum_value).allbits?(0b1010_1010 | bignum_value).should == false
-    end
+describe "Integer#allbits?" do
+  it "returns true if and only if all the bits of the argument are set in the receiver" do
+    42.allbits?(42).should == true
+    0b1010_1010.allbits?(0b1000_0010).should == true
+    0b1010_1010.allbits?(0b1000_0001).should == false
+    0b1000_0010.allbits?(0b1010_1010).should == false
+    (0b1010_1010 | bignum_value).allbits?(0b1000_0010 | bignum_value).should == true
+    (0b1010_1010 | bignum_value).allbits?(0b1000_0001 | bignum_value).should == false
+    (0b1000_0010 | bignum_value).allbits?(0b1010_1010 | bignum_value).should == false
+  end
 
-    it "handles negative values using two's complement notation" do
-      (~0b1).allbits?(42).should == true
-      (-42).allbits?(-42).should == true
-      (~0b1010_1010).allbits?(~0b1110_1011).should == true
-      (~0b1010_1010).allbits?(~0b1000_0010).should == false
-      (~(0b1010_1010 | bignum_value)).allbits?(~(0b1110_1011 | bignum_value)).should == true
-      (~(0b1010_1010 | bignum_value)).allbits?(~(0b1000_0010 | bignum_value)).should == false
-    end
+  it "handles negative values using two's complement notation" do
+    (~0b1).allbits?(42).should == true
+    (-42).allbits?(-42).should == true
+    (~0b1010_1010).allbits?(~0b1110_1011).should == true
+    (~0b1010_1010).allbits?(~0b1000_0010).should == false
+    (~(0b1010_1010 | bignum_value)).allbits?(~(0b1110_1011 | bignum_value)).should == true
+    (~(0b1010_1010 | bignum_value)).allbits?(~(0b1000_0010 | bignum_value)).should == false
+  end
 
-    it "coerces the rhs using to_int" do
-      obj = mock("the int 0b10")
-      obj.should_receive(:to_int).and_return(0b10)
-      0b110.allbits?(obj).should == true
-    end
+  it "coerces the rhs using to_int" do
+    obj = mock("the int 0b10")
+    obj.should_receive(:to_int).and_return(0b10)
+    0b110.allbits?(obj).should == true
+  end
 
-    it "raises a TypeError when given a non-Integer" do
-      -> {
-        (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
-        13.allbits?(obj)
-      }.should raise_error(TypeError)
-      -> { 13.allbits?("10")    }.should raise_error(TypeError)
-      -> { 13.allbits?(:symbol) }.should raise_error(TypeError)
-    end
+  it "raises a TypeError when given a non-Integer" do
+    -> {
+      (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
+      13.allbits?(obj)
+    }.should.raise(TypeError)
+    -> { 13.allbits?("10")    }.should.raise(TypeError)
+    -> { 13.allbits?(:symbol) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/anybits_spec.rb b/spec/ruby/core/integer/anybits_spec.rb
index 91f349258a..1ea47b76dc 100644
--- a/spec/ruby/core/integer/anybits_spec.rb
+++ b/spec/ruby/core/integer/anybits_spec.rb
@@ -1,38 +1,36 @@
 require_relative '../../spec_helper'
 
-ruby_version_is '2.5' do
-  describe "Integer#anybits?" do
-    it "returns true iff all the bits of the argument are set in the receiver" do
-      42.anybits?(42).should == true
-      0b1010_1010.anybits?(0b1000_0010).should == true
-      0b1010_1010.anybits?(0b1000_0001).should == true
-      0b1000_0010.anybits?(0b0010_1100).should == false
-      different_bignum = (2 * bignum_value) & (~bignum_value)
-      (0b1010_1010 | different_bignum).anybits?(0b1000_0010 | bignum_value).should == true
-      (0b1010_1010 | different_bignum).anybits?(0b0010_1100 | bignum_value).should == true
-      (0b1000_0010 | different_bignum).anybits?(0b0010_1100 | bignum_value).should == false
-    end
+describe "Integer#anybits?" do
+  it "returns true if and only if all the bits of the argument are set in the receiver" do
+    42.anybits?(42).should == true
+    0b1010_1010.anybits?(0b1000_0010).should == true
+    0b1010_1010.anybits?(0b1000_0001).should == true
+    0b1000_0010.anybits?(0b0010_1100).should == false
+    different_bignum = (2 * bignum_value) & (~bignum_value)
+    (0b1010_1010 | different_bignum).anybits?(0b1000_0010 | bignum_value).should == true
+    (0b1010_1010 | different_bignum).anybits?(0b0010_1100 | bignum_value).should == true
+    (0b1000_0010 | different_bignum).anybits?(0b0010_1100 | bignum_value).should == false
+  end
 
-    it "handles negative values using two's complement notation" do
-      (~42).anybits?(42).should == false
-      (-42).anybits?(-42).should == true
-      (~0b100).anybits?(~0b1).should == true
-      (~(0b100 | bignum_value)).anybits?(~(0b1 | bignum_value)).should == true
-    end
+  it "handles negative values using two's complement notation" do
+    (~42).anybits?(42).should == false
+    (-42).anybits?(-42).should == true
+    (~0b100).anybits?(~0b1).should == true
+    (~(0b100 | bignum_value)).anybits?(~(0b1 | bignum_value)).should == true
+  end
 
-    it "coerces the rhs using to_int" do
-      obj = mock("the int 0b10")
-      obj.should_receive(:to_int).and_return(0b10)
-      0b110.anybits?(obj).should == true
-    end
+  it "coerces the rhs using to_int" do
+    obj = mock("the int 0b10")
+    obj.should_receive(:to_int).and_return(0b10)
+    0b110.anybits?(obj).should == true
+  end
 
-    it "raises a TypeError when given a non-Integer" do
-      -> {
-        (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
-        13.anybits?(obj)
-      }.should raise_error(TypeError)
-      -> { 13.anybits?("10")    }.should raise_error(TypeError)
-      -> { 13.anybits?(:symbol) }.should raise_error(TypeError)
-    end
+  it "raises a TypeError when given a non-Integer" do
+    -> {
+      (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
+      13.anybits?(obj)
+    }.should.raise(TypeError)
+    -> { 13.anybits?("10")    }.should.raise(TypeError)
+    -> { 13.anybits?(:symbol) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/bit_and_spec.rb b/spec/ruby/core/integer/bit_and_spec.rb
index 15a8026855..4098ad7c7b 100644
--- a/spec/ruby/core/integer/bit_and_spec.rb
+++ b/spec/ruby/core/integer/bit_and_spec.rb
@@ -30,19 +30,19 @@ describe "Integer#&" do
 
     it "coerces the rhs and calls #coerce" do
       obj = mock("fixnum bit and")
-      obj.should_receive(:coerce).with(6).and_return([3, 6])
+      obj.should_receive(:coerce).with(6).and_return([6, 3])
       (6 & obj).should == 2
     end
 
     it "raises a TypeError when passed a Float" do
-      -> { (3 & 3.4) }.should raise_error(TypeError)
+      -> { (3 & 3.4) }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("fixnum bit and")
       obj.should_not_receive(:to_int)
 
-      -> { 3 & obj }.should raise_error(TypeError)
+      -> { 3 & obj }.should.raise(TypeError)
     end
   end
 
@@ -55,24 +55,24 @@ describe "Integer#&" do
       @bignum = bignum_value(5)
       (@bignum & 3).should == 1
       (@bignum & 52).should == 4
-      (@bignum & bignum_value(9921)).should == 9223372036854775809
+      (@bignum & bignum_value(9921)).should == 18446744073709551617
 
       ((2*bignum_value) & 1).should == 0
-      ((2*bignum_value) & (2*bignum_value)).should == 18446744073709551616
+      ((2*bignum_value) & (2*bignum_value)).should == 36893488147419103232
     end
 
     it "returns self bitwise AND other when one operand is negative" do
       ((2*bignum_value) & -1).should == (2*bignum_value)
       ((4*bignum_value) & -1).should == (4*bignum_value)
-      (@bignum & -0xffffffffffffff5).should == 9223372036854775809
+      (@bignum & -0xffffffffffffff5).should == 18446744073709551617
       (@bignum & -@bignum).should == 1
-      (@bignum & -0x8000000000000000).should == 9223372036854775808
+      (@bignum & -0x8000000000000000).should == 18446744073709551616
     end
 
     it "returns self bitwise AND other when both operands are negative" do
-      (-@bignum & -0x4000000000000005).should == -13835058055282163717
-      (-@bignum & -@bignum).should == -9223372036854775813
-      (-@bignum & -0x4000000000000000).should == -13835058055282163712
+      (-@bignum & -0x4000000000000005).should == -23058430092136939525
+      (-@bignum & -@bignum).should == -18446744073709551621
+      (-@bignum & -0x4000000000000000).should == -23058430092136939520
     end
 
     it "returns self bitwise AND other when both are negative and a multiple in bitsize of Fixnum::MIN" do
@@ -84,14 +84,14 @@ describe "Integer#&" do
     end
 
     it "raises a TypeError when passed a Float" do
-      -> { (@bignum & 3.4) }.should raise_error(TypeError)
+      -> { (@bignum & 3.4) }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("bignum bit and")
       obj.should_not_receive(:to_int)
 
-      -> { @bignum & obj }.should raise_error(TypeError)
+      -> { @bignum & obj }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/bit_or_spec.rb b/spec/ruby/core/integer/bit_or_spec.rb
index e486eeec10..c380cd729e 100644
--- a/spec/ruby/core/integer/bit_or_spec.rb
+++ b/spec/ruby/core/integer/bit_or_spec.rb
@@ -7,22 +7,43 @@ describe "Integer#|" do
       (5 | 4).should == 5
       (5 | 6).should == 7
       (248 | 4096).should == 4344
-      (0xffff | bignum_value + 0xf0f0).should == 0x8000_0000_0000_ffff
+      (0xffff | bignum_value + 0xf0f0).should == 0x1_0000_0000_0000_ffff
+    end
+
+    it "returns self bitwise OR other when one operand is negative" do
+      ((1 << 33) | -1).should == -1
+      (-1 | (1 << 33)).should == -1
+
+      ((-(1<<33)-1) | 5).should == -8589934593
+      (5 | (-(1<<33)-1)).should == -8589934593
+    end
+
+    it "returns self bitwise OR other when both operands are negative" do
+      (-5 | -1).should == -1
+      (-3 | -4).should == -3
+      (-12 | -13).should == -9
+      (-13 | -12).should == -9
     end
 
     it "returns self bitwise OR a bignum" do
       (-1 | 2**64).should == -1
     end
 
+    it "coerces the rhs and calls #coerce" do
+      obj = mock("fixnum bit or")
+      obj.should_receive(:coerce).with(6).and_return([6, 3])
+      (6 | obj).should == 7
+    end
+
     it "raises a TypeError when passed a Float" do
-      -> { (3 | 3.4) }.should raise_error(TypeError)
+      -> { (3 | 3.4) }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("integer bit or")
       obj.should_not_receive(:to_int)
 
-      -> { 3 | obj }.should raise_error(TypeError)
+      -> { 3 | obj }.should.raise(TypeError)
     end
   end
 
@@ -32,20 +53,20 @@ describe "Integer#|" do
     end
 
     it "returns self bitwise OR other" do
-      (@bignum | 2).should == 9223372036854775819
-      (@bignum | 9).should == 9223372036854775819
-      (@bignum | bignum_value).should == 9223372036854775819
+      (@bignum | 2).should == 18446744073709551627
+      (@bignum | 9).should == 18446744073709551627
+      (@bignum | bignum_value).should == 18446744073709551627
     end
 
     it "returns self bitwise OR other when one operand is negative" do
-      (@bignum | -0x40000000000000000).should == -64563604257983430645
+      (@bignum | -0x40000000000000000).should == -55340232221128654837
       (@bignum | -@bignum).should == -1
       (@bignum | -0x8000000000000000).should == -9223372036854775797
     end
 
     it "returns self bitwise OR other when both operands are negative" do
       (-@bignum | -0x4000000000000005).should == -1
-      (-@bignum | -@bignum).should == -9223372036854775819
+      (-@bignum | -@bignum).should == -18446744073709551627
       (-@bignum | -0x4000000000000000).should == -11
     end
 
@@ -53,16 +74,16 @@ describe "Integer#|" do
       not_supported_on :opal do
         -> {
           bignum_value | bignum_value(0xffff).to_f
-        }.should raise_error(TypeError)
+        }.should.raise(TypeError)
       end
-      -> { @bignum | 9.9 }.should raise_error(TypeError)
+      -> { @bignum | 9.9 }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("bignum bit or")
       obj.should_not_receive(:to_int)
 
-      -> { @bignum | obj }.should raise_error(TypeError)
+      -> { @bignum | obj }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/bit_xor_spec.rb b/spec/ruby/core/integer/bit_xor_spec.rb
index ac8826a52f..c0cf8405f7 100644
--- a/spec/ruby/core/integer/bit_xor_spec.rb
+++ b/spec/ruby/core/integer/bit_xor_spec.rb
@@ -5,22 +5,43 @@ describe "Integer#^" do
     it "returns self bitwise EXCLUSIVE OR other" do
       (3 ^ 5).should == 6
       (-2 ^ -255).should == 255
-      (5 ^ bignum_value + 0xffff_ffff).should == 0x8000_0000_ffff_fffa
+      (5 ^ bignum_value + 0xffff_ffff).should == 0x1_0000_0000_ffff_fffa
+    end
+
+    it "returns self bitwise XOR other when one operand is negative" do
+      ((1 << 33) ^ -1).should == -8589934593
+      (-1 ^ (1 << 33)).should == -8589934593
+
+      ((-(1<<33)-1) ^ 5).should == -8589934598
+      (5 ^ (-(1<<33)-1)).should == -8589934598
+    end
+
+    it "returns self bitwise XOR other when both operands are negative" do
+      (-5 ^ -1).should == 4
+      (-3 ^ -4).should == 1
+      (-12 ^ -13).should == 7
+      (-13 ^ -12).should == 7
     end
 
     it "returns self bitwise EXCLUSIVE OR a bignum" do
       (-1 ^ 2**64).should == -18446744073709551617
     end
 
+    it "coerces the rhs and calls #coerce" do
+      obj = mock("fixnum bit xor")
+      obj.should_receive(:coerce).with(6).and_return([6, 3])
+      (6 ^ obj).should == 5
+    end
+
     it "raises a TypeError when passed a Float" do
-      -> { (3 ^ 3.4) }.should raise_error(TypeError)
+      -> { (3 ^ 3.4) }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("integer bit xor")
       obj.should_not_receive(:to_int)
 
-      -> { 3 ^ obj }.should raise_error(TypeError)
+      -> { 3 ^ obj }.should.raise(TypeError)
     end
   end
 
@@ -30,21 +51,21 @@ describe "Integer#^" do
     end
 
     it "returns self bitwise EXCLUSIVE OR other" do
-      (@bignum ^ 2).should == 9223372036854775824
+      (@bignum ^ 2).should == 18446744073709551632
       (@bignum ^ @bignum).should == 0
-      (@bignum ^ 14).should == 9223372036854775836
+      (@bignum ^ 14).should == 18446744073709551644
     end
 
     it "returns self bitwise EXCLUSIVE OR other when one operand is negative" do
-      (@bignum ^ -0x40000000000000000).should == -64563604257983430638
+      (@bignum ^ -0x40000000000000000).should == -55340232221128654830
       (@bignum ^ -@bignum).should == -4
-      (@bignum ^ -0x8000000000000000).should == -18446744073709551598
+      (@bignum ^ -0x8000000000000000).should == -27670116110564327406
     end
 
     it "returns self bitwise EXCLUSIVE OR other when both operands are negative" do
-      (-@bignum ^ -0x40000000000000000).should == 64563604257983430638
+      (-@bignum ^ -0x40000000000000000).should == 55340232221128654830
       (-@bignum ^ -@bignum).should == 0
-      (-@bignum ^ -0x4000000000000000).should == 13835058055282163694
+      (-@bignum ^ -0x4000000000000000).should == 23058430092136939502
     end
 
     it "returns self bitwise EXCLUSIVE OR other when all bits are 1 and other value is negative" do
@@ -57,16 +78,16 @@ describe "Integer#^" do
       not_supported_on :opal do
         -> {
           bignum_value ^ bignum_value(0xffff).to_f
-        }.should raise_error(TypeError)
+        }.should.raise(TypeError)
       end
-      -> { @bignum ^ 14.5 }.should raise_error(TypeError)
+      -> { @bignum ^ 14.5 }.should.raise(TypeError)
     end
 
     it "raises a TypeError and does not call #to_int when defined on an object" do
       obj = mock("bignum bit xor")
       obj.should_not_receive(:to_int)
 
-      -> { @bignum ^ obj }.should raise_error(TypeError)
+      -> { @bignum ^ obj }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/ceil_spec.rb b/spec/ruby/core/integer/ceil_spec.rb
index 13bdaf838d..395be58fbd 100644
--- a/spec/ruby/core/integer/ceil_spec.rb
+++ b/spec/ruby/core/integer/ceil_spec.rb
@@ -1,19 +1,13 @@
 require_relative '../../spec_helper'
 require_relative 'shared/to_i'
 require_relative 'shared/integer_rounding'
+require_relative 'shared/integer_ceil_precision'
 
 describe "Integer#ceil" do
   it_behaves_like :integer_to_i, :ceil
   it_behaves_like :integer_rounding_positive_precision, :ceil
 
-  context "precision argument specified as part of the ceil method is negative" do
-    it "returns the smallest integer greater than self with at least precision.abs trailing zeros" do
-      18.ceil(-1).should eql(20)
-      18.ceil(-2).should eql(100)
-      18.ceil(-3).should eql(1000)
-      -1832.ceil(-1).should eql(-1830)
-      -1832.ceil(-2).should eql(-1800)
-      -1832.ceil(-3).should eql(-1000)
-    end
+  context "with precision" do
+    it_behaves_like :integer_ceil_precision, :Integer
   end
 end
diff --git a/spec/ruby/core/integer/ceildiv_spec.rb b/spec/ruby/core/integer/ceildiv_spec.rb
new file mode 100644
index 0000000000..91f63832f8
--- /dev/null
+++ b/spec/ruby/core/integer/ceildiv_spec.rb
@@ -0,0 +1,20 @@
+require_relative '../../spec_helper'
+
+describe "Integer#ceildiv" do
+  it "returns a quotient of division which is rounded up to the nearest integer" do
+    0.ceildiv(3).should.eql?(0)
+    1.ceildiv(3).should.eql?(1)
+    3.ceildiv(3).should.eql?(1)
+    4.ceildiv(3).should.eql?(2)
+
+    4.ceildiv(-3).should.eql?(-1)
+    -4.ceildiv(3).should.eql?(-1)
+    -4.ceildiv(-3).should.eql?(2)
+
+    3.ceildiv(1.2).should.eql?(3)
+    3.ceildiv(6/5r).should.eql?(3)
+
+    (10**100-11).ceildiv(10**99-1).should.eql?(10)
+    (10**100-9).ceildiv(10**99-1).should.eql?(11)
+  end
+end
diff --git a/spec/ruby/core/integer/chr_spec.rb b/spec/ruby/core/integer/chr_spec.rb
index a8755eeb84..72784e1833 100644
--- a/spec/ruby/core/integer/chr_spec.rb
+++ b/spec/ruby/core/integer/chr_spec.rb
@@ -2,16 +2,20 @@ require_relative '../../spec_helper'
 
 describe "Integer#chr without argument" do
   it "returns a String" do
-    17.chr.should be_an_instance_of(String)
+    17.chr.should.instance_of?(String)
   end
 
   it "returns a new String for each call" do
-    82.chr.should_not equal(82.chr)
+    82.chr.should_not.equal?(82.chr)
   end
 
   it "raises a RangeError is self is less than 0" do
-    -> { -1.chr }.should raise_error(RangeError)
-    -> { -bignum_value.chr }.should raise_error(RangeError)
+    -> { -1.chr }.should.raise(RangeError, /-1 out of char range/)
+    -> { (-bignum_value).chr }.should.raise(RangeError, /bignum out of char range/)
+  end
+
+  it "raises a RangeError if self is too large" do
+    -> { 2206368128.chr(Encoding::UTF_8) }.should.raise(RangeError, /2206368128 out of char range/)
   end
 
   describe "when Encoding.default_internal is nil" do
@@ -44,8 +48,8 @@ describe "Integer#chr without argument" do
     end
 
     it "raises a RangeError is self is greater than 255" do
-      -> { 256.chr }.should raise_error(RangeError)
-      -> { bignum_value.chr }.should raise_error(RangeError)
+      -> { 256.chr }.should.raise(RangeError, /256 out of char range/)
+      -> { bignum_value.chr }.should.raise(RangeError, /bignum out of char range/)
     end
   end
 
@@ -133,7 +137,7 @@ describe "Integer#chr without argument" do
           [620,    "TIS-620"]
         ].each do |integer, encoding_name|
           Encoding.default_internal = Encoding.find(encoding_name)
-          -> { integer.chr }.should raise_error(RangeError)
+          -> { integer.chr }.should.raise(RangeError, /(invalid codepoint|out of char range)/)
         end
       end
     end
@@ -142,15 +146,15 @@ end
 
 describe "Integer#chr with an encoding argument" do
   it "returns a String" do
-    900.chr(Encoding::UTF_8).should be_an_instance_of(String)
+    900.chr(Encoding::UTF_8).should.instance_of?(String)
   end
 
   it "returns a new String for each call" do
-    8287.chr(Encoding::UTF_8).should_not equal(8287.chr(Encoding::UTF_8))
+    8287.chr(Encoding::UTF_8).should_not.equal?(8287.chr(Encoding::UTF_8))
   end
 
   it "accepts a String as an argument" do
-    -> { 0xA4A2.chr('euc-jp') }.should_not raise_error
+    -> { 0xA4A2.chr('euc-jp') }.should_not.raise
   end
 
   it "converts a String to an Encoding as Encoding.find does" do
@@ -161,12 +165,12 @@ describe "Integer#chr with an encoding argument" do
 
   # http://redmine.ruby-lang.org/issues/4869
   it "raises a RangeError is self is less than 0" do
-    -> { -1.chr(Encoding::UTF_8) }.should raise_error(RangeError)
-    -> { -bignum_value.chr(Encoding::EUC_JP) }.should raise_error(RangeError)
+    -> { -1.chr(Encoding::UTF_8) }.should.raise(RangeError, /-1 out of char range/)
+    -> { (-bignum_value).chr(Encoding::EUC_JP) }.should.raise(RangeError, /bignum out of char range/)
   end
 
   it "raises a RangeError if self is too large" do
-    -> { 2206368128.chr(Encoding::UTF_8) }.should raise_error(RangeError)
+    -> { 2206368128.chr(Encoding::UTF_8) }.should.raise(RangeError, /2206368128 out of char range/)
   end
 
   it "returns a String with the specified encoding" do
@@ -219,25 +223,35 @@ describe "Integer#chr with an encoding argument" do
 
   # #5864
   it "raises RangeError if self is invalid as a codepoint in the specified encoding" do
-    [ [0x80,   "US-ASCII"],
-      [0x0100, "BINARY"],
-      [0x0100, "EUC-JP"],
-      [0xA1A0, "EUC-JP"],
-      [0xA1,   "EUC-JP"],
-      [0x80,   "SHIFT_JIS"],
-      [0xE0,   "SHIFT_JIS"],
-      [0x0100, "ISO-8859-9"],
-      [620,    "TIS-620"],
-      [0xD800, "UTF-8"],
-      [0xDBFF, "UTF-8"],
-      [0xDC00, "UTF-8"],
-      [0xDFFF, "UTF-8"],
-      [0xD800, "UTF-16"],
-      [0xDBFF, "UTF-16"],
-      [0xDC00, "UTF-16"],
-      [0xDFFF, "UTF-16"],
-    ].each do |integer, encoding_name|
-      -> { integer.chr(encoding_name) }.should raise_error(RangeError)
-    end
+    -> { 0x80.chr("US-ASCII") }.should.raise(RangeError)
+    -> { 0x0100.chr("BINARY") }.should.raise(RangeError)
+    -> { 0x0100.chr("EUC-JP") }.should.raise(RangeError)
+    -> { 0xA1A0.chr("EUC-JP") }.should.raise(RangeError)
+    -> { 0xA1.chr("EUC-JP") }.should.raise(RangeError)
+    -> { 0x80.chr("SHIFT_JIS") }.should.raise(RangeError)
+    -> { 0xE0.chr("SHIFT_JIS") }.should.raise(RangeError)
+    -> { 0x0100.chr("ISO-8859-9") }.should.raise(RangeError)
+    -> { 620.chr("TIS-620") }.should.raise(RangeError)
+    # UTF-16 surrogate range
+    -> { 0xD800.chr("UTF-8") }.should.raise(RangeError)
+    -> { 0xDBFF.chr("UTF-8") }.should.raise(RangeError)
+    -> { 0xDC00.chr("UTF-8") }.should.raise(RangeError)
+    -> { 0xDFFF.chr("UTF-8") }.should.raise(RangeError)
+    # UTF-16 surrogate range
+    -> { 0xD800.chr("UTF-16") }.should.raise(RangeError)
+    -> { 0xDBFF.chr("UTF-16") }.should.raise(RangeError)
+    -> { 0xDC00.chr("UTF-16") }.should.raise(RangeError)
+    -> { 0xDFFF.chr("UTF-16") }.should.raise(RangeError)
+  end
+
+  it 'returns a String encoding self interpreted as a codepoint in the CESU-8 encoding' do
+    # see more details here https://en.wikipedia.org/wiki/CESU-8
+    # code points from U+0000 to U+FFFF is encoded in the same way as in UTF-8
+    0x0045.chr(Encoding::CESU_8).bytes.should == 0x0045.chr(Encoding::UTF_8).bytes
+
+    # code points in range from U+10000 to U+10FFFF is CESU-8 data containing a 6-byte surrogate pair,
+    # which decodes to a 4-byte UTF-8 string
+    0x10400.chr(Encoding::CESU_8).bytes.should != 0x10400.chr(Encoding::UTF_8).bytes
+    0x10400.chr(Encoding::CESU_8).bytes.to_a.should == [0xED, 0xA0, 0x81, 0xED, 0xB0, 0x80]
   end
 end
diff --git a/spec/ruby/core/integer/coerce_spec.rb b/spec/ruby/core/integer/coerce_spec.rb
index 9a19baf2ea..c0e642da03 100644
--- a/spec/ruby/core/integer/coerce_spec.rb
+++ b/spec/ruby/core/integer/coerce_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../spec_helper'
 
-require 'bigdecimal'
-
 describe "Integer#coerce" do
   context "fixnum" do
     describe "when given a Fixnum" do
       it "returns an array containing two Fixnums" do
         1.coerce(2).should == [2, 1]
-        1.coerce(2).map { |i| i.class }.should == [Fixnum, Fixnum]
+        1.coerce(2).map { |i| i.class }.should == [Integer, Integer]
       end
     end
 
     describe "when given a String" do
       it "raises an ArgumentError when trying to coerce with a non-number String" do
-        -> { 1.coerce(":)") }.should raise_error(ArgumentError)
+        -> { 1.coerce(":)") }.should.raise(ArgumentError)
       end
 
       it "returns  an array containing two Floats" do
@@ -23,7 +21,7 @@ describe "Integer#coerce" do
     end
 
     it "raises a TypeError when trying to coerce with nil" do
-      -> { 1.coerce(nil) }.should raise_error(TypeError)
+      -> { 1.coerce(nil) }.should.raise(TypeError)
     end
 
     it "tries to convert the given Object into a Float by using #to_f" do
@@ -31,13 +29,13 @@ describe "Integer#coerce" do
       2.coerce(obj).should == [1.0, 2.0]
 
       (obj = mock('0')).should_receive(:to_f).and_return('0')
-      -> { 2.coerce(obj).should == [1.0, 2.0] }.should raise_error(TypeError)
+      -> { 2.coerce(obj).should == [1.0, 2.0] }.should.raise(TypeError)
     end
 
     it "raises a TypeError when given an Object that does not respond to #to_f" do
-      -> { 1.coerce(mock('x'))  }.should raise_error(TypeError)
-      -> { 1.coerce(1..4)       }.should raise_error(TypeError)
-      -> { 1.coerce(:test)      }.should raise_error(TypeError)
+      -> { 1.coerce(mock('x'))  }.should.raise(TypeError)
+      -> { 1.coerce(1..4)       }.should.raise(TypeError)
+      -> { 1.coerce(:test)      }.should.raise(TypeError)
     end
   end
 
@@ -46,8 +44,8 @@ describe "Integer#coerce" do
       a = bignum_value
       ary = a.coerce(2)
 
-      ary[0].should be_kind_of(Bignum)
-      ary[1].should be_kind_of(Bignum)
+      ary[0].should.is_a?(Integer)
+      ary[1].should.is_a?(Integer)
       ary.should == [2, a]
     end
 
@@ -56,18 +54,18 @@ describe "Integer#coerce" do
       b = bignum_value
       ary = a.coerce(b)
 
-      ary[0].should be_kind_of(Bignum)
-      ary[1].should be_kind_of(Bignum)
+      ary[0].should.is_a?(Integer)
+      ary[1].should.is_a?(Integer)
       ary.should == [b, a]
     end
 
     it "raises a TypeError when not passed a Fixnum or Bignum" do
       a = bignum_value
 
-      -> { a.coerce(nil)         }.should raise_error(TypeError)
-      -> { a.coerce(mock('str')) }.should raise_error(TypeError)
-      -> { a.coerce(1..4)        }.should raise_error(TypeError)
-      -> { a.coerce(:test)       }.should raise_error(TypeError)
+      -> { a.coerce(nil)         }.should.raise(TypeError)
+      -> { a.coerce(mock('str')) }.should.raise(TypeError)
+      -> { a.coerce(1..4)        }.should.raise(TypeError)
+      -> { a.coerce(:test)       }.should.raise(TypeError)
     end
 
     it "coerces both values to Floats and returns [other, self] when passed a Float" do
@@ -90,15 +88,4 @@ describe "Integer#coerce" do
       ary.should == [1.2, a.to_f]
     end
   end
-
-  context "bigdecimal" do
-    it "produces Floats" do
-      x, y = 3.coerce(BigDecimal("3.4"))
-      x.class.should == Float
-      x.should == 3.4
-      y.class.should == Float
-      y.should == 3.0
-    end
-  end
-
 end
diff --git a/spec/ruby/core/integer/comparison_spec.rb b/spec/ruby/core/integer/comparison_spec.rb
index 762af51535..cc5cbe2506 100644
--- a/spec/ruby/core/integer/comparison_spec.rb
+++ b/spec/ruby/core/integer/comparison_spec.rb
@@ -116,7 +116,7 @@ describe "Integer#<=>" do
     describe "with an Object" do
       before :each do
         @big = bignum_value
-        @num = mock("value for Bignum#<=>")
+        @num = mock("value for Integer#<=>")
       end
 
       it "calls #coerce on other" do
@@ -124,33 +124,21 @@ describe "Integer#<=>" do
         @big <=> @num
       end
 
-      ruby_version_is ""..."2.5" do
-        it "returns nil if #coerce raises an exception" do
-          @num.should_receive(:coerce).with(@big).and_raise(RuntimeError)
-          -> {
-            @result = (@big <=> @num)
-          }.should complain(/Numerical comparison operators will no more rescue exceptions/)
-          @result.should be_nil
-        end
-      end
-
-      ruby_version_is "2.5" do
-        it "lets the exception go through if #coerce raises an exception" do
-          @num.should_receive(:coerce).with(@big).and_raise(RuntimeError.new("my error"))
-          -> {
-            @big <=> @num
-          }.should raise_error(RuntimeError, "my error")
-        end
+      it "lets the exception go through if #coerce raises an exception" do
+        @num.should_receive(:coerce).with(@big).and_raise(RuntimeError.new("my error"))
+        -> {
+          @big <=> @num
+        }.should.raise(RuntimeError, "my error")
       end
 
       it "raises an exception if #coerce raises a non-StandardError exception" do
         @num.should_receive(:coerce).with(@big).and_raise(Exception)
-        -> { @big <=> @num }.should raise_error(Exception)
+        -> { @big <=> @num }.should.raise(Exception)
       end
 
       it "returns nil if #coerce does not return an Array" do
         @num.should_receive(:coerce).with(@big).and_return(nil)
-        (@big <=> @num).should be_nil
+        (@big <=> @num).should == nil
       end
 
       it "returns -1 if the coerced value is larger" do
@@ -169,12 +157,20 @@ describe "Integer#<=>" do
       end
     end
 
+    describe "with a Float" do
+      it "does not lose precision for values that don't fit in a double" do
+        (bignum_value(1) <=> bignum_value.to_f).should == 1
+        (bignum_value <=> bignum_value.to_f).should == 0
+        ((bignum_value - 1) <=> bignum_value.to_f).should == -1
+      end
+    end
+
     # The tests below are taken from matz's revision 23730 for Ruby trunk
     it "returns 1 when self is Infinity and other is a Bignum" do
       (infinity_value <=> Float::MAX.to_i*2).should == 1
     end
 
-    it "returns -1 when self is negative and other is Infinty" do
+    it "returns -1 when self is negative and other is Infinity" do
       (-Float::MAX.to_i*2 <=> infinity_value).should == -1
     end
 
diff --git a/spec/ruby/core/integer/complement_spec.rb b/spec/ruby/core/integer/complement_spec.rb
index eafa5c263f..baf5e6c457 100644
--- a/spec/ruby/core/integer/complement_spec.rb
+++ b/spec/ruby/core/integer/complement_spec.rb
@@ -12,9 +12,9 @@ describe "Integer#~" do
 
   context "bignum" do
     it "returns self with each bit flipped" do
-      (~bignum_value(48)).should == -9223372036854775857
-      (~(-bignum_value(21))).should == 9223372036854775828
-      (~bignum_value(1)).should == -9223372036854775810
+      (~bignum_value(48)).should == -18446744073709551665
+      (~(-bignum_value(21))).should == 18446744073709551636
+      (~bignum_value(1)).should == -18446744073709551618
     end
   end
 end
diff --git a/spec/ruby/core/integer/constants_spec.rb b/spec/ruby/core/integer/constants_spec.rb
new file mode 100644
index 0000000000..937806c72f
--- /dev/null
+++ b/spec/ruby/core/integer/constants_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "Fixnum" do
+  it "is no longer defined" do
+    Object.should_not.const_defined?(:Fixnum)
+  end
+end
+
+describe "Bignum" do
+  it "is no longer defined" do
+    Object.should_not.const_defined?(:Bignum)
+  end
+end
diff --git a/spec/ruby/core/integer/digits_spec.rb b/spec/ruby/core/integer/digits_spec.rb
index 4a8e33980c..c4ebf2cd88 100644
--- a/spec/ruby/core/integer/digits_spec.rb
+++ b/spec/ruby/core/integer/digits_spec.rb
@@ -19,14 +19,23 @@ describe "Integer#digits" do
   end
 
   it "raises ArgumentError when calling with a radix less than 2" do
-    -> { 12345.digits(1) }.should raise_error(ArgumentError)
+    -> { 12345.digits(1) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError when calling with a negative radix" do
-    -> { 12345.digits(-2) }.should raise_error(ArgumentError)
+    -> { 12345.digits(-2) }.should.raise(ArgumentError)
   end
 
   it "raises Math::DomainError when calling digits on a negative number" do
-    -> { -12345.digits(7) }.should raise_error(Math::DomainError)
+    -> { -12345.digits(7) }.should.raise(Math::DomainError)
+  end
+
+  it "returns integer values > 9 when base is above 10" do
+    1234.digits(16).should == [2, 13, 4]
+  end
+
+  it "can be used with base > 37" do
+    1234.digits(100).should == [34, 12]
+    980099.digits(100).should == [99, 0, 98]
   end
 end
diff --git a/spec/ruby/core/integer/div_spec.rb b/spec/ruby/core/integer/div_spec.rb
index 087d012fe0..220ca4a73e 100644
--- a/spec/ruby/core/integer/div_spec.rb
+++ b/spec/ruby/core/integer/div_spec.rb
@@ -36,7 +36,7 @@ describe "Integer#div" do
       10.div(y).should == result
     end
 
-    it "coerces self and the given argument to Floats and returns self divided by other as Fixnum" do
+    it "coerces self and the given argument to Floats and returns self divided by other as Integer" do
       1.div(0.2).should == 5
       1.div(0.16).should == 6
       1.div(0.169).should == 5
@@ -46,21 +46,21 @@ describe "Integer#div" do
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and a Float" do
-      -> { 0.div(0.0)   }.should raise_error(ZeroDivisionError)
-      -> { 10.div(0.0)  }.should raise_error(ZeroDivisionError)
-      -> { -10.div(0.0) }.should raise_error(ZeroDivisionError)
+      -> { 0.div(0.0)   }.should.raise(ZeroDivisionError)
+      -> { 10.div(0.0)  }.should.raise(ZeroDivisionError)
+      -> { -10.div(0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and not a Float" do
-      -> { 13.div(0) }.should raise_error(ZeroDivisionError)
-      -> { 13.div(-0) }.should raise_error(ZeroDivisionError)
+      -> { 13.div(0) }.should.raise(ZeroDivisionError)
+      -> { 13.div(-0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when given a non-numeric argument" do
-      -> { 13.div(mock('10')) }.should raise_error(TypeError)
-      -> { 5.div("2") }.should raise_error(TypeError)
-      -> { 5.div(:"2") }.should raise_error(TypeError)
-      -> { 5.div([]) }.should raise_error(TypeError)
+      -> { 13.div(mock('10')) }.should.raise(TypeError)
+      -> { 5.div("2") }.should.raise(TypeError)
+      -> { 5.div(:"2") }.should.raise(TypeError)
+      -> { 5.div([]) }.should.raise(TypeError)
     end
   end
 
@@ -70,8 +70,8 @@ describe "Integer#div" do
     end
 
     it "returns self divided by other" do
-      @bignum.div(4).should == 2305843009213693974
-      @bignum.div(Rational(4, 1)).should == 2305843009213693974
+      @bignum.div(4).should == 4611686018427387926
+      @bignum.div(Rational(4, 1)).should == 4611686018427387926
       @bignum.div(bignum_value(2)).should == 1
 
       (-(10**50)).div(-(10**40 + 1)).should == 9999999999
@@ -118,29 +118,37 @@ describe "Integer#div" do
     end
 
     it "raises a TypeError when given a non-numeric" do
-      -> { @bignum.div(mock("10")) }.should raise_error(TypeError)
-      -> { @bignum.div("2") }.should raise_error(TypeError)
-      -> { @bignum.div(:symbol) }.should raise_error(TypeError)
+      -> { @bignum.div(mock("10")) }.should.raise(TypeError)
+      -> { @bignum.div("2") }.should.raise(TypeError)
+      -> { @bignum.div(:symbol) }.should.raise(TypeError)
     end
 
     it "returns a result of integer division of self by a float argument" do
-      @bignum.div(4294967295.5).should eql(2147483648)
+      @bignum.div(4294967295.5).should.eql?(4294967296)
       not_supported_on :opal do
-        @bignum.div(4294967295.0).should eql(2147483648)
-        @bignum.div(bignum_value(88).to_f).should eql(1)
-        @bignum.div(-bignum_value(88).to_f).should eql(-1)
+        @bignum.div(4294967295.0).should.eql?(4294967297)
+        @bignum.div(bignum_value(88).to_f).should.eql?(1)
+        @bignum.div((-bignum_value(88)).to_f).should.eql?(-1)
       end
     end
 
     # #5490
     it "raises ZeroDivisionError if the argument is 0 and is a Float" do
-      -> { @bignum.div(0.0) }.should raise_error(ZeroDivisionError)
-      -> { @bignum.div(-0.0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.div(0.0) }.should.raise(ZeroDivisionError)
+      -> { @bignum.div(-0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises ZeroDivisionError if the argument is 0 and is not a Float" do
-      -> { @bignum.div(0) }.should raise_error(ZeroDivisionError)
-      -> { @bignum.div(-0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.div(0) }.should.raise(ZeroDivisionError)
+      -> { @bignum.div(-0) }.should.raise(ZeroDivisionError)
+    end
+  end
+
+  context "rational" do
+    it "returns self divided by the given argument as an Integer" do
+      2.div(6/5r).should == 1
+      1.div(6/5r).should == 0
+      5.div(6/5r).should == 4
     end
   end
 end
diff --git a/spec/ruby/core/integer/divide_spec.rb b/spec/ruby/core/integer/divide_spec.rb
index a32d68c229..e75432fd83 100644
--- a/spec/ruby/core/integer/divide_spec.rb
+++ b/spec/ruby/core/integer/divide_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/arithmetic_coerce'
 
 describe "Integer#/" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_arithmetic_coerce_rescue, :/
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_arithmetic_coerce_not_rescue, :/
-  end
+  it_behaves_like :integer_arithmetic_coerce_not_rescue, :/
 
   context "fixnum" do
     it "returns self divided by the given argument" do
@@ -18,6 +12,17 @@ describe "Integer#/" do
 
     it "supports dividing negative numbers" do
       (-1 / 10).should == -1
+      (-1 / 10**10).should == -1
+      (-1 / 10**20).should == -1
+    end
+
+    it "preservers sign correctly" do
+      (4 / 3).should == 1
+      (4 / -3).should == -2
+      (-4 / 3).should == -2
+      (-4 / -3).should == 1
+      (0 / -3).should == 0
+      (0 / 3).should == 0
     end
 
     it "returns result the same class as the argument" do
@@ -27,7 +32,7 @@ describe "Integer#/" do
     end
 
     it "raises a ZeroDivisionError if the given argument is zero and not a Float" do
-      -> { 1 / 0 }.should raise_error(ZeroDivisionError)
+      -> { 1 / 0 }.should.raise(ZeroDivisionError)
     end
 
     it "does NOT raise ZeroDivisionError if the given argument is zero and is a Float" do
@@ -41,9 +46,9 @@ describe "Integer#/" do
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { 13 / mock('10') }.should raise_error(TypeError)
-      -> { 13 / "10"       }.should raise_error(TypeError)
-      -> { 13 / :symbol    }.should raise_error(TypeError)
+      -> { 13 / mock('10') }.should.raise(TypeError)
+      -> { 13 / "10"       }.should.raise(TypeError)
+      -> { 13 / :symbol    }.should.raise(TypeError)
     end
   end
 
@@ -53,7 +58,7 @@ describe "Integer#/" do
     end
 
     it "returns self divided by other" do
-      (@bignum / 4).should == 2305843009213693974
+      (@bignum / 4).should == 4611686018427387926
 
       (@bignum / bignum_value(2)).should == 1
 
@@ -64,17 +69,26 @@ describe "Integer#/" do
       ((10**50) / -(10**40 + 1)).should == -10000000000
     end
 
+    it "preservers sign correctly" do
+      (4 / bignum_value).should == 0
+      (4 / -bignum_value).should == -1
+      (-4 / bignum_value).should == -1
+      (-4 / -bignum_value).should == 0
+      (0 / bignum_value).should == 0
+      (0 / -bignum_value).should == 0
+    end
+
     it "returns self divided by Float" do
       not_supported_on :opal do
-        (bignum_value(88) / 4294967295.0).should be_close(2147483648.5, TOLERANCE)
+        (bignum_value(88) / 4294967295.0).should be_close(4294967297.0, TOLERANCE)
       end
-      (bignum_value(88) / 4294967295.5).should be_close(2147483648.25, TOLERANCE)
+      (bignum_value(88) / 4294967295.5).should be_close(4294967296.5, TOLERANCE)
     end
 
     it "returns result the same class as the argument" do
-      (@bignum / 4).should == 2305843009213693974
-      (@bignum / 4.0).should be_close(2305843009213693974, TOLERANCE)
-      (@bignum / Rational(4, 1)).should == Rational(2305843009213693974, 1)
+      (@bignum / 4).should == 4611686018427387926
+      (@bignum / 4.0).should be_close(4611686018427387926, TOLERANCE)
+      (@bignum / Rational(4, 1)).should == Rational(4611686018427387926, 1)
     end
 
     it "does NOT raise ZeroDivisionError if other is zero and is a Float" do
@@ -83,13 +97,30 @@ describe "Integer#/" do
     end
 
     it "raises a ZeroDivisionError if other is zero and not a Float" do
-      -> { @bignum / 0 }.should raise_error(ZeroDivisionError)
+      -> { @bignum / 0 }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when given a non-numeric" do
-      -> { @bignum / mock('10') }.should raise_error(TypeError)
-      -> { @bignum / "2" }.should raise_error(TypeError)
-      -> { @bignum / :symbol }.should raise_error(TypeError)
+      -> { @bignum / mock('10') }.should.raise(TypeError)
+      -> { @bignum / "2" }.should.raise(TypeError)
+      -> { @bignum / :symbol }.should.raise(TypeError)
     end
   end
+
+  it "coerces the RHS and calls #coerce" do
+    obj = mock("integer plus")
+    obj.should_receive(:coerce).with(6).and_return([6, 3])
+    (6 / obj).should == 2
+  end
+
+  it "coerces the RHS and calls #coerce even if it's private" do
+    obj = Object.new
+    class << obj
+      private def coerce(n)
+        [n, 3]
+      end
+    end
+
+    (6 / obj).should == 2
+  end
 end
diff --git a/spec/ruby/core/integer/divmod_spec.rb b/spec/ruby/core/integer/divmod_spec.rb
index d88925caad..db470c5731 100644
--- a/spec/ruby/core/integer/divmod_spec.rb
+++ b/spec/ruby/core/integer/divmod_spec.rb
@@ -14,24 +14,24 @@ describe "Integer#divmod" do
     end
 
     it "raises a ZeroDivisionError when the given argument is 0" do
-      -> { 13.divmod(0)  }.should raise_error(ZeroDivisionError)
-      -> { 0.divmod(0)   }.should raise_error(ZeroDivisionError)
-      -> { -10.divmod(0) }.should raise_error(ZeroDivisionError)
+      -> { 13.divmod(0)  }.should.raise(ZeroDivisionError)
+      -> { 0.divmod(0)   }.should.raise(ZeroDivisionError)
+      -> { -10.divmod(0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and a Float" do
-      -> { 0.divmod(0.0)   }.should raise_error(ZeroDivisionError)
-      -> { 10.divmod(0.0)  }.should raise_error(ZeroDivisionError)
-      -> { -10.divmod(0.0) }.should raise_error(ZeroDivisionError)
+      -> { 0.divmod(0.0)   }.should.raise(ZeroDivisionError)
+      -> { 10.divmod(0.0)  }.should.raise(ZeroDivisionError)
+      -> { -10.divmod(0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when given a non-Integer" do
       -> {
         (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
         13.divmod(obj)
-      }.should raise_error(TypeError)
-      -> { 13.divmod("10")    }.should raise_error(TypeError)
-      -> { 13.divmod(:symbol) }.should raise_error(TypeError)
+      }.should.raise(TypeError)
+      -> { 13.divmod("10")    }.should.raise(TypeError)
+      -> { 13.divmod(:symbol) }.should.raise(TypeError)
     end
   end
 
@@ -46,16 +46,16 @@ describe "Integer#divmod" do
     # assert(0 < b ? (0 <= r && r < b) : (b < r && r <= 0))
     # So, r is always between 0 and b.
     it "returns an Array containing quotient and modulus obtained from dividing self by the given argument" do
-      @bignum.divmod(4).should == [2305843009213693965, 3]
-      @bignum.divmod(13).should == [709490156681136604, 11]
+      @bignum.divmod(4).should == [4611686018427387917, 3]
+      @bignum.divmod(13).should == [1418980313362273205, 6]
 
-      @bignum.divmod(4.5).should == [2049638230412172288, 3.5]
+      @bignum.divmod(4.5).should == [4099276460824344576, 2.5]
 
       not_supported_on :opal do
-        @bignum.divmod(4.0).should == [2305843009213693952, 0.0]
-        @bignum.divmod(13.0).should == [709490156681136640, 8.0]
+        @bignum.divmod(4.0).should == [4611686018427387904, 0.0]
+        @bignum.divmod(13.0).should == [1418980313362273280, 3.0]
 
-        @bignum.divmod(2.0).should == [4611686018427387904, 0.0]
+        @bignum.divmod(2.0).should == [9223372036854775808, 0.0]
       end
 
       @bignum.divmod(bignum_value).should == [1, 55]
@@ -94,24 +94,24 @@ describe "Integer#divmod" do
     end
 
     it "raises a ZeroDivisionError when the given argument is 0" do
-      -> { @bignum.divmod(0) }.should raise_error(ZeroDivisionError)
-      -> { (-@bignum).divmod(0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.divmod(0) }.should.raise(ZeroDivisionError)
+      -> { (-@bignum).divmod(0) }.should.raise(ZeroDivisionError)
     end
 
     # Behaviour established as correct in r23953
     it "raises a FloatDomainError if other is NaN" do
-      -> { @bignum.divmod(nan_value) }.should raise_error(FloatDomainError)
+      -> { @bignum.divmod(nan_value) }.should.raise(FloatDomainError)
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and a Float" do
-      -> { @bignum.divmod(0.0) }.should raise_error(ZeroDivisionError)
-      -> { (-@bignum).divmod(0.0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.divmod(0.0) }.should.raise(ZeroDivisionError)
+      -> { (-@bignum).divmod(0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when the given argument is not an Integer" do
-      -> { @bignum.divmod(mock('10')) }.should raise_error(TypeError)
-      -> { @bignum.divmod("10") }.should raise_error(TypeError)
-      -> { @bignum.divmod(:symbol) }.should raise_error(TypeError)
+      -> { @bignum.divmod(mock('10')) }.should.raise(TypeError)
+      -> { @bignum.divmod("10") }.should.raise(TypeError)
+      -> { @bignum.divmod(:symbol) }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/downto_spec.rb b/spec/ruby/core/integer/downto_spec.rb
index af7a7e36b9..a244d3df55 100644
--- a/spec/ruby/core/integer/downto_spec.rb
+++ b/spec/ruby/core/integer/downto_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
 
-describe "Integer#downto [stop] when self and stop are Fixnums" do
+describe "Integer#downto [stop] when self and stop are Integers" do
   it "does not yield when stop is greater than self" do
     result = []
     5.downto(6) { |x| result << x }
@@ -27,8 +27,8 @@ describe "Integer#downto [stop] when self and stop are Fixnums" do
   end
 
   it "raises an ArgumentError for invalid endpoints" do
-    -> {1.downto("A") {|x| p x } }.should raise_error(ArgumentError)
-    -> {1.downto(nil) {|x| p x } }.should raise_error(ArgumentError)
+    -> {1.downto("A") {|x| p x } }.should.raise(ArgumentError)
+    -> {1.downto(nil) {|x| p x } }.should.raise(ArgumentError)
   end
 
   describe "when no block is given" do
@@ -45,9 +45,9 @@ describe "Integer#downto [stop] when self and stop are Fixnums" do
       describe "size" do
         it "raises an ArgumentError for invalid endpoints" do
           enum = 1.downto("A")
-          -> { enum.size }.should raise_error(ArgumentError)
+          -> { enum.size }.should.raise(ArgumentError)
           enum = 1.downto(nil)
-          -> { enum.size }.should raise_error(ArgumentError)
+          -> { enum.size }.should.raise(ArgumentError)
         end
 
         it "returns self - stop + 1" do
diff --git a/spec/ruby/core/integer/dup_spec.rb b/spec/ruby/core/integer/dup_spec.rb
index 7f4d512465..3e5739ad37 100644
--- a/spec/ruby/core/integer/dup_spec.rb
+++ b/spec/ruby/core/integer/dup_spec.rb
@@ -3,11 +3,11 @@ require_relative '../../spec_helper'
 describe "Integer#dup" do
   it "returns self for small integers" do
     integer = 1_000
-    integer.dup.should equal(integer)
+    integer.dup.should.equal?(integer)
   end
 
   it "returns self for large integers" do
     integer = 4_611_686_018_427_387_905
-    integer.dup.should equal(integer)
+    integer.dup.should.equal?(integer)
   end
 end
diff --git a/spec/ruby/core/integer/element_reference_spec.rb b/spec/ruby/core/integer/element_reference_spec.rb
index 99283fac34..c69ec2315d 100644
--- a/spec/ruby/core/integer/element_reference_spec.rb
+++ b/spec/ruby/core/integer/element_reference_spec.rb
@@ -59,13 +59,13 @@ describe "Integer#[]" do
     end
 
     it "raises a TypeError when passed a String" do
-      -> { 3["3"] }.should raise_error(TypeError)
+      -> { 3["3"] }.should.raise(TypeError)
     end
 
     it "raises a TypeError when #to_int does not return an Integer" do
       obj = mock('asdf')
       obj.should_receive(:to_int).and_return("asdf")
-      -> { 3[obj] }.should raise_error(TypeError)
+      -> { 3[obj] }.should.raise(TypeError)
     end
 
     it "calls #to_int to coerce a String to a Bignum and returns 0" do
@@ -78,6 +78,83 @@ describe "Integer#[]" do
     it "returns 0 when passed a Float in the range of a Bignum" do
       3[bignum_value.to_f].should == 0
     end
+
+    context "when index and length passed" do
+      it "returns specified number of bits from specified position" do
+        0b101001101[2, 4].should ==    0b0011
+        0b101001101[2, 5].should ==   0b10011
+        0b101001101[2, 7].should == 0b1010011
+      end
+
+      it "ensures n[i, len] equals to (n >> i) & ((1 << len) - 1)" do
+        n = 0b101001101; i = 2; len = 4
+        n[i, len].should == (n >> i) & ((1 << len) - 1)
+      end
+
+      it "moves start position to the most significant bits when negative index passed" do
+        0b000001[-1, 4].should == 0b10
+        0b000001[-2, 4].should == 0b100
+        0b000001[-3, 4].should == 0b1000
+      end
+
+      it "ignores negative length" do
+        0b101001101[1, -1].should == 0b10100110
+        0b101001101[2, -1].should == 0b1010011
+        0b101001101[3, -1].should == 0b101001
+
+        0b101001101[3,   -5].should == 0b101001
+        0b101001101[3,  -15].should == 0b101001
+        0b101001101[3, -125].should == 0b101001
+      end
+    end
+
+    context "when range passed" do
+      it "returns bits specified by range" do
+        0b101001101[2..5].should ==    0b0011
+        0b101001101[2..6].should ==   0b10011
+        0b101001101[2..8].should == 0b1010011
+      end
+
+      it "ensures n[i..j] equals to (n >> i) & ((1 << (j - i + 1)) - 1)" do
+        n = 0b101001101; i = 2; j = 5
+        n[i..j].should == (n >> i) & ((1 << (j - i + 1)) - 1)
+      end
+
+      it "ensures n[i..] equals to (n >> i)" do
+        eval("0b101001101[3..]").should == 0b101001101 >> 3
+      end
+
+      it "moves lower boundary to the most significant bits when negative value passed" do
+        0b000001[-1, 4].should == 0b10
+        0b000001[-2, 4].should == 0b100
+        0b000001[-3, 4].should == 0b1000
+      end
+
+      it "ignores upper boundary smaller than lower boundary" do
+        0b101001101[4..1].should == 0b10100
+        0b101001101[4..2].should == 0b10100
+        0b101001101[-4..-5].should == 0b1010011010000
+      end
+
+      it "raises FloatDomainError if any boundary is infinity" do
+        -> { 0x0001[3..Float::INFINITY] }.should.raise(FloatDomainError, /Infinity/)
+        -> { 0x0001[-Float::INFINITY..3] }.should.raise(FloatDomainError, /-Infinity/)
+      end
+
+      context "when passed (..i)" do
+        it "returns 0 if all i bits equal 0" do
+          eval("0b10000[..1]").should == 0
+          eval("0b10000[..2]").should == 0
+          eval("0b10000[..3]").should == 0
+        end
+
+        it "raises ArgumentError if any of i bit equals 1" do
+          -> {
+            eval("0b111110[..3]")
+          }.should.raise(ArgumentError, /The beginless range for Integer#\[\] results in infinity/)
+        end
+      end
+    end
   end
 
   context "bignum" do
@@ -102,10 +179,10 @@ describe "Integer#[]" do
 
     it "raises a TypeError when the given argument can't be converted to Integer" do
       obj = mock('asdf')
-      -> { @bignum[obj] }.should raise_error(TypeError)
+      -> { @bignum[obj] }.should.raise(TypeError)
 
       obj.should_receive(:to_int).and_return("asdf")
-      -> { @bignum[obj] }.should raise_error(TypeError)
+      -> { @bignum[obj] }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/eql_spec.rb b/spec/ruby/core/integer/eql_spec.rb
new file mode 100644
index 0000000000..9c80173206
--- /dev/null
+++ b/spec/ruby/core/integer/eql_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+
+describe "Integer#eql?" do
+  context "bignum" do
+    it "returns true for the same value" do
+      bignum_value.eql?(bignum_value).should == true
+    end
+
+    it "returns false for a different Integer value" do
+      bignum_value.eql?(bignum_value(1)).should == false
+    end
+
+    it "returns false for a Float with the same numeric value" do
+      bignum_value.eql?(bignum_value.to_f).should == false
+    end
+
+    it "returns false for a Rational with the same numeric value" do
+      bignum_value.eql?(Rational(bignum_value)).should == false
+    end
+
+    it "returns false for a Fixnum-range Integer" do
+      bignum_value.eql?(42).should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/integer/even_spec.rb b/spec/ruby/core/integer/even_spec.rb
index a314cc6b19..578979320e 100644
--- a/spec/ruby/core/integer/even_spec.rb
+++ b/spec/ruby/core/integer/even_spec.rb
@@ -3,38 +3,38 @@ require_relative '../../spec_helper'
 describe "Integer#even?" do
   context "fixnum" do
     it "returns true for a Fixnum when it is an even number" do
-      (-2).even?.should be_true
-      (-1).even?.should be_false
+      (-2).even?.should == true
+      (-1).even?.should == false
 
-      0.even?.should be_true
-      1.even?.should be_false
-      2.even?.should be_true
+      0.even?.should == true
+      1.even?.should == false
+      2.even?.should == true
     end
 
     it "returns true for a Bignum when it is an even number" do
-      bignum_value(0).even?.should be_true
-      bignum_value(1).even?.should be_false
+      bignum_value(0).even?.should == true
+      bignum_value(1).even?.should == false
 
-      (-bignum_value(0)).even?.should be_true
-      (-bignum_value(1)).even?.should be_false
+      (-bignum_value(0)).even?.should == true
+      (-bignum_value(1)).even?.should == false
     end
   end
 
   context "bignum" do
     it "returns true if self is even and positive" do
-      (10000**10).even?.should be_true
+      (10000**10).even?.should == true
     end
 
     it "returns true if self is even and negative" do
-      (-10000**10).even?.should be_true
+      (-10000**10).even?.should == true
     end
 
     it "returns false if self is odd and positive" do
-      (9879**976).even?.should be_false
+      (9879**976).even?.should == false
     end
 
     it "returns false if self is odd and negative" do
-      (-9879**976).even?.should be_false
+      (-9879**976).even?.should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/fdiv_spec.rb b/spec/ruby/core/integer/fdiv_spec.rb
index 6de170278f..7854d66dec 100644
--- a/spec/ruby/core/integer/fdiv_spec.rb
+++ b/spec/ruby/core/integer/fdiv_spec.rb
@@ -9,13 +9,64 @@ describe "Integer#fdiv" do
     8.fdiv(bignum_value).should be_close(8.673617379884035e-19, TOLERANCE)
   end
 
+  it "performs floating-point division between self bignum and a bignum" do
+    num = 1000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146010000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146010000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146009
+    den = 2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+    num.fdiv(den).should == 500.0
+  end
+
+  it "rounds to the correct value for bignums" do
+    den = 9 * 10**342
+
+    num = 1 * 10**344
+    num.fdiv(den).should == 11.11111111111111
+
+    num = 1 * 10**343
+    num.fdiv(den).should == 1.1111111111111112
+
+    num = 1 * 10**342
+    num.fdiv(den).should == 0.1111111111111111
+
+    num = 2 * 10**342
+    num.fdiv(den).should == 0.2222222222222222
+
+    num = 3 * 10**342
+    num.fdiv(den).should == 0.3333333333333333
+
+    num = 4 * 10**342
+    num.fdiv(den).should == 0.4444444444444444
+
+    num = 5 * 10**342
+    num.fdiv(den).should == 0.5555555555555556
+
+    num = 6 * 10**342
+    num.fdiv(den).should == 0.6666666666666666
+
+    num = 7 * 10**342
+    num.fdiv(den).should == 0.7777777777777778
+
+    num = 8 * 10**342
+    num.fdiv(den).should == 0.8888888888888888
+
+    num = 9 * 10**342
+    num.fdiv(den).should == 1.0
+
+    num = -5 * 10**342
+    num.fdiv(den).should == -0.5555555555555556
+  end
+
+  it "rounds to the correct float for bignum denominators" do
+    1.fdiv(10**324).should == 0.0
+    1.fdiv(10**323).should == 1.0e-323
+  end
+
   it "performs floating-point division between self and a Float" do
     8.fdiv(9.0).should be_close(0.888888888888889, TOLERANCE)
   end
 
   it "returns NaN when the argument is NaN" do
-    -1.fdiv(nan_value).nan?.should be_true
-    1.fdiv(nan_value).nan?.should be_true
+    -1.fdiv(nan_value).nan?.should == true
+    1.fdiv(nan_value).nan?.should == true
   end
 
   it "returns Infinity when the argument is 0" do
@@ -35,11 +86,11 @@ describe "Integer#fdiv" do
   end
 
   it "raises a TypeError when argument isn't numeric" do
-    -> { 1.fdiv(mock('non-numeric')) }.should raise_error(TypeError)
+    -> { 1.fdiv(mock('non-numeric')) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when passed multiple arguments" do
-    -> { 1.fdiv(6,0.2) }.should raise_error(ArgumentError)
+    -> { 1.fdiv(6,0.2) }.should.raise(ArgumentError)
   end
 
   it "follows the coercion protocol" do
diff --git a/spec/ruby/core/integer/fixtures/classes.rb b/spec/ruby/core/integer/fixtures/classes.rb
index 6ebfbd1565..65948efb9f 100644
--- a/spec/ruby/core/integer/fixtures/classes.rb
+++ b/spec/ruby/core/integer/fixtures/classes.rb
@@ -1,4 +1,14 @@
 module IntegerSpecs
   class CoerceError < StandardError
   end
+
+  class CoercibleNumeric
+    def initialize(v) @v = v end
+    def coerce(other) [self.class.new(other), self] end
+    def >(other)  @v.to_i > other.to_i  end
+    def >=(other) @v.to_i >= other.to_i end
+    def <(other)  @v.to_i < other.to_i  end
+    def <=(other) @v.to_i <= other.to_i end
+    def to_i()    @v.to_i               end
+  end
 end
diff --git a/spec/ruby/core/integer/floor_spec.rb b/spec/ruby/core/integer/floor_spec.rb
index aaa816fdc5..8fb84d58cb 100644
--- a/spec/ruby/core/integer/floor_spec.rb
+++ b/spec/ruby/core/integer/floor_spec.rb
@@ -1,19 +1,13 @@
 require_relative '../../spec_helper'
 require_relative 'shared/to_i'
 require_relative 'shared/integer_rounding'
+require_relative 'shared/integer_floor_precision'
 
 describe "Integer#floor" do
   it_behaves_like :integer_to_i, :floor
   it_behaves_like :integer_rounding_positive_precision, :floor
 
-  context "precision argument specified as part of the floor method is negative" do
-    it "returns the largest integer less than self with at least precision.abs trailing zeros" do
-      1832.floor(-1).should eql(1830)
-      1832.floor(-2).should eql(1800)
-      1832.floor(-3).should eql(1000)
-      -1832.floor(-1).should eql(-1840)
-      -1832.floor(-2).should eql(-1900)
-      -1832.floor(-3).should eql(-2000)
-    end
+  context "with precision" do
+    it_behaves_like :integer_floor_precision, :Integer
   end
 end
diff --git a/spec/ruby/core/integer/gcd_spec.rb b/spec/ruby/core/integer/gcd_spec.rb
index 8aa654a16a..1fff785927 100644
--- a/spec/ruby/core/integer/gcd_spec.rb
+++ b/spec/ruby/core/integer/gcd_spec.rb
@@ -7,8 +7,8 @@ describe "Integer#gcd" do
   end
 
   it "returns an Integer" do
-    36.gcd(6).should be_kind_of(Integer)
-    4.gcd(20981).should be_kind_of(Integer)
+    36.gcd(6).should.is_a?(Integer)
+    4.gcd(20981).should.is_a?(Integer)
   end
 
   it "returns the greatest common divisor of self and argument" do
@@ -33,13 +33,13 @@ describe "Integer#gcd" do
 
   it "accepts a Bignum argument" do
     bignum = 9999**99
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     99.gcd(bignum).should == 99
   end
 
   it "works if self is a Bignum" do
     bignum = 9999**99
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     bignum.gcd(99).should == 99
   end
 
@@ -55,15 +55,15 @@ describe "Integer#gcd" do
   end
 
   it "raises an ArgumentError if not given an argument" do
-    -> { 12.gcd }.should raise_error(ArgumentError)
+    -> { 12.gcd }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if given more than one argument" do
-    -> { 12.gcd(30, 20) }.should raise_error(ArgumentError)
+    -> { 12.gcd(30, 20) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError unless the argument is an Integer" do
-    -> { 39.gcd(3.8)   }.should raise_error(TypeError)
-    -> { 45872.gcd([]) }.should raise_error(TypeError)
+    -> { 39.gcd(3.8)   }.should.raise(TypeError)
+    -> { 45872.gcd([]) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/gcdlcm_spec.rb b/spec/ruby/core/integer/gcdlcm_spec.rb
index 5b3669e62a..419bf9f275 100644
--- a/spec/ruby/core/integer/gcdlcm_spec.rb
+++ b/spec/ruby/core/integer/gcdlcm_spec.rb
@@ -7,8 +7,8 @@ describe "Integer#gcdlcm" do
   end
 
   it "returns an Array" do
-    36.gcdlcm(6).should be_kind_of(Array)
-    4.gcdlcm(20981).should be_kind_of(Array)
+    36.gcdlcm(6).should.is_a?(Array)
+    4.gcdlcm(20981).should.is_a?(Array)
   end
 
   it "returns a two-element Array" do
@@ -28,26 +28,26 @@ describe "Integer#gcdlcm" do
 
   it "accepts a Bignum argument" do
     bignum = 91999**99
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     99.gcdlcm(bignum).should == [99.gcd(bignum), 99.lcm(bignum)]
   end
 
   it "works if self is a Bignum" do
     bignum = 9999**89
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     bignum.gcdlcm(99).should == [bignum.gcd(99), bignum.lcm(99)]
   end
 
   it "raises an ArgumentError if not given an argument" do
-    -> { 12.gcdlcm }.should raise_error(ArgumentError)
+    -> { 12.gcdlcm }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if given more than one argument" do
-    -> { 12.gcdlcm(30, 20) }.should raise_error(ArgumentError)
+    -> { 12.gcdlcm(30, 20) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError unless the argument is an Integer" do
-    -> { 39.gcdlcm(3.8)   }.should raise_error(TypeError)
-    -> { 45872.gcdlcm([]) }.should raise_error(TypeError)
+    -> { 39.gcdlcm(3.8)   }.should.raise(TypeError)
+    -> { 45872.gcdlcm([]) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/gt_spec.rb b/spec/ruby/core/integer/gt_spec.rb
index 428a6f6888..75436144cf 100644
--- a/spec/ruby/core/integer/gt_spec.rb
+++ b/spec/ruby/core/integer/gt_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/comparison_coerce'
 
 describe "Integer#>" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_comparison_coerce_rescue, :>
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_comparison_coerce_not_rescue, :>
-  end
+  it_behaves_like :integer_comparison_coerce_not_rescue, :>
 
   context "fixnum" do
     it "returns true if self is greater than the given argument" do
@@ -23,8 +17,8 @@ describe "Integer#>" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { 5 > "4"       }.should raise_error(ArgumentError)
-      -> { 5 > mock('x') }.should raise_error(ArgumentError)
+      -> { 5 > "4"       }.should.raise(ArgumentError)
+      -> { 5 > mock('x') }.should.raise(ArgumentError)
     end
   end
 
@@ -42,8 +36,13 @@ describe "Integer#>" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { @bignum > "4" }.should raise_error(ArgumentError)
-      -> { @bignum > mock('str') }.should raise_error(ArgumentError)
+      -> { @bignum > "4" }.should.raise(ArgumentError)
+      -> { @bignum > mock('str') }.should.raise(ArgumentError)
+    end
+
+    it "dispatches the correct operator after coercion" do
+      (bignum_value > IntegerSpecs::CoercibleNumeric.new(1)).should == true
+      (bignum_value > IntegerSpecs::CoercibleNumeric.new(bignum_value * 2)).should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/gte_spec.rb b/spec/ruby/core/integer/gte_spec.rb
index ce1385c360..e5cb892efd 100644
--- a/spec/ruby/core/integer/gte_spec.rb
+++ b/spec/ruby/core/integer/gte_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/comparison_coerce'
 
 describe "Integer#>=" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_comparison_coerce_rescue, :>=
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_comparison_coerce_not_rescue, :>=
-  end
+  it_behaves_like :integer_comparison_coerce_not_rescue, :>=
 
   context "fixnum" do
     it "returns true if self is greater than or equal to the given argument" do
@@ -24,8 +18,8 @@ describe "Integer#>=" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { 5 >= "4"       }.should raise_error(ArgumentError)
-      -> { 5 >= mock('x') }.should raise_error(ArgumentError)
+      -> { 5 >= "4"       }.should.raise(ArgumentError)
+      -> { 5 >= mock('x') }.should.raise(ArgumentError)
     end
   end
 
@@ -42,8 +36,13 @@ describe "Integer#>=" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { @bignum >= "4" }.should raise_error(ArgumentError)
-      -> { @bignum >= mock('str') }.should raise_error(ArgumentError)
+      -> { @bignum >= "4" }.should.raise(ArgumentError)
+      -> { @bignum >= mock('str') }.should.raise(ArgumentError)
+    end
+
+    it "dispatches the correct operator after coercion" do
+      (bignum_value >= IntegerSpecs::CoercibleNumeric.new(1)).should == true
+      (bignum_value >= IntegerSpecs::CoercibleNumeric.new(bignum_value * 2)).should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/integer_spec.rb b/spec/ruby/core/integer/integer_spec.rb
index f8067cda06..19a962d548 100644
--- a/spec/ruby/core/integer/integer_spec.rb
+++ b/spec/ruby/core/integer/integer_spec.rb
@@ -6,15 +6,15 @@ describe "Integer" do
   end
 
   it "is the class of both small and large integers" do
-    42.class.should equal(Integer)
-    bignum_value.class.should equal(Integer)
+    42.class.should.equal?(Integer)
+    bignum_value.class.should.equal?(Integer)
   end
 end
 
 describe "Integer#integer?" do
   it "returns true for Integers" do
-    0.integer?.should == true
-    -1.integer?.should == true
-    bignum_value.integer?.should == true
+    0.should.integer?
+    -1.should.integer?
+    bignum_value.should.integer?
   end
 end
diff --git a/spec/ruby/core/integer/lcm_spec.rb b/spec/ruby/core/integer/lcm_spec.rb
index 77d3ad3488..6659247d1e 100644
--- a/spec/ruby/core/integer/lcm_spec.rb
+++ b/spec/ruby/core/integer/lcm_spec.rb
@@ -7,8 +7,8 @@ describe "Integer#lcm" do
   end
 
   it "returns an Integer" do
-    36.lcm(6).should be_kind_of(Integer)
-    4.lcm(20981).should be_kind_of(Integer)
+    36.lcm(6).should.is_a?(Integer)
+    4.lcm(20981).should.is_a?(Integer)
   end
 
   it "returns the least common multiple of self and argument" do
@@ -33,26 +33,26 @@ describe "Integer#lcm" do
 
   it "accepts a Bignum argument" do
     bignum = 9999**99
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     99.lcm(bignum).should == bignum
   end
 
   it "works if self is a Bignum" do
     bignum = 9999**99
-    bignum.should be_kind_of(Bignum)
+    bignum.should.is_a?(Integer)
     bignum.lcm(99).should == bignum
   end
 
   it "raises an ArgumentError if not given an argument" do
-    -> { 12.lcm }.should raise_error(ArgumentError)
+    -> { 12.lcm }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if given more than one argument" do
-    -> { 12.lcm(30, 20) }.should raise_error(ArgumentError)
+    -> { 12.lcm(30, 20) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError unless the argument is an Integer" do
-    -> { 39.lcm(3.8)   }.should raise_error(TypeError)
-    -> { 45872.lcm([]) }.should raise_error(TypeError)
+    -> { 39.lcm(3.8)   }.should.raise(TypeError)
+    -> { 45872.lcm([]) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/left_shift_spec.rb b/spec/ruby/core/integer/left_shift_spec.rb
index 4b5ef9386e..7eedb91228 100644
--- a/spec/ruby/core/integer/left_shift_spec.rb
+++ b/spec/ruby/core/integer/left_shift_spec.rb
@@ -56,44 +56,47 @@ describe "Integer#<< (with n << m)" do
       (3 << -bignum_value).should == 0
     end
 
-    it "returns an Bignum == fixnum_max * 2 when fixnum_max << 1 and n > 0" do
+    it "returns a Bignum == fixnum_max * 2 when fixnum_max << 1 and n > 0" do
       result = fixnum_max << 1
-      result.should be_an_instance_of(Bignum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_max * 2
     end
 
-    it "returns an Bignum == fixnum_min * 2 when fixnum_min << 1 and n < 0" do
+    it "returns a Bignum == fixnum_min * 2 when fixnum_min << 1 and n < 0" do
       result = fixnum_min << 1
-      result.should be_an_instance_of(Bignum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_min * 2
     end
 
     it "calls #to_int to convert the argument to an Integer" do
       obj = mock("4")
       obj.should_receive(:to_int).and_return(4)
-
       (3 << obj).should == 48
+
+      obj = mock("to_int_neg_bignum")
+      obj.should_receive(:to_int).and_return(-bignum_value)
+      (3 << obj).should == 0
     end
 
     it "raises a TypeError when #to_int does not return an Integer" do
       obj = mock("a string")
       obj.should_receive(:to_int).and_return("asdf")
 
-      -> { 3 << obj }.should raise_error(TypeError)
+      -> { 3 << obj }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed nil" do
-      -> { 3 << nil }.should raise_error(TypeError)
+      -> { 3 << nil }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed a String" do
-      -> { 3 << "4" }.should raise_error(TypeError)
+      -> { 3 << "4" }.should.raise(TypeError)
     end
   end
 
   context "bignum" do
     before :each do
-      @bignum = bignum_value * 16
+      @bignum = bignum_value * 8 # 2 ** 67
     end
 
     it "returns n shifted left m bits when n > 0, m > 0" do
@@ -124,19 +127,15 @@ describe "Integer#<< (with n << m)" do
       (@bignum << -68).should == 0
     end
 
-    it "returns 0 when m < 0 and m is a Bignum" do
-      (@bignum << -bignum_value).should == 0
-    end
-
     it "returns a Fixnum == fixnum_max when (fixnum_max * 2) << -1 and n > 0" do
       result = (fixnum_max * 2) << -1
-      result.should be_an_instance_of(Fixnum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_max
     end
 
     it "returns a Fixnum == fixnum_min when (fixnum_min * 2) << -1 and n < 0" do
       result = (fixnum_min * 2) << -1
-      result.should be_an_instance_of(Fixnum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_min
     end
 
@@ -151,15 +150,62 @@ describe "Integer#<< (with n << m)" do
       obj = mock("a string")
       obj.should_receive(:to_int).and_return("asdf")
 
-      -> { @bignum << obj }.should raise_error(TypeError)
+      -> { @bignum << obj }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed nil" do
-      -> { @bignum << nil }.should raise_error(TypeError)
+      -> { @bignum << nil }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed a String" do
-      -> { @bignum << "4" }.should raise_error(TypeError)
+      -> { @bignum << "4" }.should.raise(TypeError)
+    end
+  end
+
+  context "when m is a bignum or larger than int" do
+    it "returns -1 when m < 0 and n < 0" do
+      (-1 << -bignum_value).should == -1
+      (-1 << -(2**40)).should == -1
+
+      (-bignum_value << -bignum_value).should == -1
+      (-bignum_value << -(2**40)).should == -1
+    end
+
+    it "returns 0 when m < 0 and n >= 0" do
+      (0 << -bignum_value).should == 0
+      (1 << -bignum_value).should == 0
+      (bignum_value << -bignum_value).should == 0
+
+      (0 << -(2**40)).should == 0
+      (1 << -(2**40)).should == 0
+      (bignum_value << -(2**40)).should == 0
+    end
+
+    it "returns 0 when m > 0 long and n == 0" do
+      (0 << (2**40)).should == 0
+    end
+
+    it "returns 0 when m > 0 bignum and n == 0" do
+      (0 << bignum_value).should == 0
+    end
+
+    it "raises RangeError when m > 0 and n != 0" do
+      # https://bugs.ruby-lang.org/issues/18518#note-9
+      limit = RUBY_ENGINE == 'ruby' ? 2**67 : 2**32
+
+      coerce_long = mock("long")
+      coerce_long.stub!(:to_int).and_return(limit)
+      coerce_bignum = mock("bignum")
+      coerce_bignum.stub!(:to_int).and_return(bignum_value)
+      exps = [limit, coerce_long]
+      exps << bignum_value << coerce_bignum if bignum_value >= limit
+
+      exps.each { |exp|
+        -> { (1 << exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (-1 << exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (bignum_value << exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (-bignum_value << exp) }.should.raise(RangeError, 'shift width too big')
+      }
     end
   end
 end
diff --git a/spec/ruby/core/integer/lt_spec.rb b/spec/ruby/core/integer/lt_spec.rb
index dfe2d9e369..dd1391d093 100644
--- a/spec/ruby/core/integer/lt_spec.rb
+++ b/spec/ruby/core/integer/lt_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/comparison_coerce'
 
 describe "Integer#<" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_comparison_coerce_rescue, :<
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_comparison_coerce_not_rescue, :<
-  end
+  it_behaves_like :integer_comparison_coerce_not_rescue, :<
 
   context "fixnum" do
     it "returns true if self is less than the given argument" do
@@ -23,8 +17,8 @@ describe "Integer#<" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { 5 < "4"       }.should raise_error(ArgumentError)
-      -> { 5 < mock('x') }.should raise_error(ArgumentError)
+      -> { 5 < "4"       }.should.raise(ArgumentError)
+      -> { 5 < mock('x') }.should.raise(ArgumentError)
     end
   end
 
@@ -44,8 +38,13 @@ describe "Integer#<" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { @bignum < "4" }.should raise_error(ArgumentError)
-      -> { @bignum < mock('str') }.should raise_error(ArgumentError)
+      -> { @bignum < "4" }.should.raise(ArgumentError)
+      -> { @bignum < mock('str') }.should.raise(ArgumentError)
+    end
+
+    it "dispatches the correct operator after coercion" do
+      (bignum_value < IntegerSpecs::CoercibleNumeric.new(bignum_value * 2)).should == true
+      (bignum_value < IntegerSpecs::CoercibleNumeric.new(1)).should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/lte_spec.rb b/spec/ruby/core/integer/lte_spec.rb
index 3d843a5dd9..9ef1c9f604 100644
--- a/spec/ruby/core/integer/lte_spec.rb
+++ b/spec/ruby/core/integer/lte_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/comparison_coerce'
 
 describe "Integer#<=" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_comparison_coerce_rescue, :<=
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_comparison_coerce_not_rescue, :<=
-  end
+  it_behaves_like :integer_comparison_coerce_not_rescue, :<=
 
   context "fixnum" do
     it "returns true if self is less than or equal to other" do
@@ -24,8 +18,8 @@ describe "Integer#<=" do
     end
 
     it "raises an ArgumentError when given a non-Integer" do
-      -> { 5 <= "4"       }.should raise_error(ArgumentError)
-      -> { 5 <= mock('x') }.should raise_error(ArgumentError)
+      -> { 5 <= "4"       }.should.raise(ArgumentError)
+      -> { 5 <= mock('x') }.should.raise(ArgumentError)
     end
   end
 
@@ -46,9 +40,19 @@ describe "Integer#<=" do
       (@bignum <= (@bignum + 0.5)).should == false
     end
 
+    it "returns true for bignums compare to a bigger float" do
+      (18446744073709551616 <= 1.8446744073709552e+19).should == true
+      (@bignum <= (@bignum + 9999.0)).should == true
+    end
+
     it "raises an ArgumentError when given a non-Integer" do
-      -> { @bignum <= "4" }.should raise_error(ArgumentError)
-      -> { @bignum <= mock('str') }.should raise_error(ArgumentError)
+      -> { @bignum <= "4" }.should.raise(ArgumentError)
+      -> { @bignum <= mock('str') }.should.raise(ArgumentError)
+    end
+
+    it "dispatches the correct operator after coercion" do
+      (bignum_value <= IntegerSpecs::CoercibleNumeric.new(bignum_value * 2)).should == true
+      (bignum_value <= IntegerSpecs::CoercibleNumeric.new(1)).should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/minus_spec.rb b/spec/ruby/core/integer/minus_spec.rb
index 34dd36c1a7..5fd3a81a72 100644
--- a/spec/ruby/core/integer/minus_spec.rb
+++ b/spec/ruby/core/integer/minus_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/arithmetic_coerce'
 
 describe "Integer#-" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_arithmetic_coerce_rescue, :-
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_arithmetic_coerce_not_rescue, :-
-  end
+  it_behaves_like :integer_arithmetic_coerce_not_rescue, :-
 
   context "fixnum" do
     it "returns self minus the given Integer" do
@@ -16,16 +10,16 @@ describe "Integer#-" do
       (9237212 - 5_280).should == 9231932
 
       (781 - 0.5).should == 780.5
-      (2_560_496 - bignum_value).should == -9223372036852215312
+      (2_560_496 - bignum_value).should == -18446744073706991120
     end
 
     it "raises a TypeError when given a non-Integer" do
       -> {
         (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
         13 - obj
-      }.should raise_error(TypeError)
-      -> { 13 - "10"    }.should raise_error(TypeError)
-      -> { 13 - :symbol }.should raise_error(TypeError)
+      }.should.raise(TypeError)
+      -> { 13 - "10"    }.should.raise(TypeError)
+      -> { 13 - :symbol }.should.raise(TypeError)
     end
   end
 
@@ -35,15 +29,32 @@ describe "Integer#-" do
     end
 
     it "returns self minus the given Integer" do
-      (@bignum - 9).should == 9223372036854776113
-      (@bignum - 12.57).should be_close(9223372036854776109.43, TOLERANCE)
+      (@bignum - 9).should == 18446744073709551921
+      (@bignum - 12.57).should be_close(18446744073709551917.43, TOLERANCE)
       (@bignum - bignum_value(42)).should == 272
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { @bignum - mock('10') }.should raise_error(TypeError)
-      -> { @bignum - "10" }.should raise_error(TypeError)
-      -> { @bignum - :symbol }.should raise_error(TypeError)
+      -> { @bignum - mock('10') }.should.raise(TypeError)
+      -> { @bignum - "10" }.should.raise(TypeError)
+      -> { @bignum - :symbol }.should.raise(TypeError)
     end
   end
+
+  it "coerces the RHS and calls #coerce" do
+    obj = mock("integer plus")
+    obj.should_receive(:coerce).with(5).and_return([5, 10])
+    (5 - obj).should == -5
+  end
+
+  it "coerces the RHS and calls #coerce even if it's private" do
+    obj = Object.new
+    class << obj
+      private def coerce(n)
+        [n, 10]
+      end
+    end
+
+    (5 - obj).should == -5
+  end
 end
diff --git a/spec/ruby/core/integer/multiply_spec.rb b/spec/ruby/core/integer/multiply_spec.rb
index 919786cbcc..7f30eebaa5 100644
--- a/spec/ruby/core/integer/multiply_spec.rb
+++ b/spec/ruby/core/integer/multiply_spec.rb
@@ -2,13 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'shared/arithmetic_coerce'
 
 describe "Integer#*" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_arithmetic_coerce_rescue, :*
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_arithmetic_coerce_not_rescue, :*
-  end
+  it_behaves_like :integer_arithmetic_coerce_not_rescue, :*
 
   context "fixnum" do
     it "returns self multiplied by the given Integer" do
@@ -16,7 +10,7 @@ describe "Integer#*" do
       (1342177 * 800).should == 1073741600
       (65536 * 65536).should == 4294967296
 
-      (256 * bignum_value).should == 2361183241434822606848
+      (256 * bignum_value).should == 4722366482869645213696
       (6712 * 0.25).should == 1678.0
     end
 
@@ -24,9 +18,9 @@ describe "Integer#*" do
       -> {
         (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
         13 * obj
-      }.should raise_error(TypeError)
-      -> { 13 * "10"    }.should raise_error(TypeError)
-      -> { 13 * :symbol }.should raise_error(TypeError)
+      }.should.raise(TypeError)
+      -> { 13 * "10"    }.should.raise(TypeError)
+      -> { 13 * :symbol }.should.raise(TypeError)
     end
   end
 
@@ -38,14 +32,14 @@ describe "Integer#*" do
     it "returns self multiplied by the given Integer" do
       (@bignum * (1/bignum_value(0xffff).to_f)).should be_close(1.0, TOLERANCE)
       (@bignum * (1/bignum_value(0xffff).to_f)).should be_close(1.0, TOLERANCE)
-      (@bignum * 10).should == 92233720368547765800
-      (@bignum * (@bignum - 40)).should == 85070591730234629737795195287525433200
+      (@bignum * 10).should == 184467440737095523880
+      (@bignum * (@bignum - 40)).should == 340282366920938491207277694290934407024
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { @bignum * mock('10') }.should raise_error(TypeError)
-      -> { @bignum * "10" }.should raise_error(TypeError)
-      -> { @bignum * :symbol }.should raise_error(TypeError)
+      -> { @bignum * mock('10') }.should.raise(TypeError)
+      -> { @bignum * "10" }.should.raise(TypeError)
+      -> { @bignum * :symbol }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/nobits_spec.rb b/spec/ruby/core/integer/nobits_spec.rb
index af3b9e7db0..f1a3aca9d5 100644
--- a/spec/ruby/core/integer/nobits_spec.rb
+++ b/spec/ruby/core/integer/nobits_spec.rb
@@ -1,38 +1,36 @@
 require_relative '../../spec_helper'
 
-ruby_version_is '2.5' do
-  describe "Integer#nobits?" do
-    it "returns true iff all no bits of the argument are set in the receiver" do
-      42.nobits?(42).should == false
-      0b1010_1010.nobits?(0b1000_0010).should == false
-      0b1010_1010.nobits?(0b1000_0001).should == false
-      0b0100_0101.nobits?(0b1010_1010).should == true
-      different_bignum = (2 * bignum_value) & (~bignum_value)
-      (0b1010_1010 | different_bignum).nobits?(0b1000_0010 | bignum_value).should == false
-      (0b1010_1010 | different_bignum).nobits?(0b1000_0001 | bignum_value).should == false
-      (0b0100_0101 | different_bignum).nobits?(0b1010_1010 | bignum_value).should == true
-    end
+describe "Integer#nobits?" do
+  it "returns true if and only if all no bits of the argument are set in the receiver" do
+    42.nobits?(42).should == false
+    0b1010_1010.nobits?(0b1000_0010).should == false
+    0b1010_1010.nobits?(0b1000_0001).should == false
+    0b0100_0101.nobits?(0b1010_1010).should == true
+    different_bignum = (2 * bignum_value) & (~bignum_value)
+    (0b1010_1010 | different_bignum).nobits?(0b1000_0010 | bignum_value).should == false
+    (0b1010_1010 | different_bignum).nobits?(0b1000_0001 | bignum_value).should == false
+    (0b0100_0101 | different_bignum).nobits?(0b1010_1010 | bignum_value).should == true
+  end
 
-    it "handles negative values using two's complement notation" do
-      (~0b1101).nobits?(0b1101).should == true
-      (-42).nobits?(-42).should == false
-      (~0b1101).nobits?(~0b10).should == false
-      (~(0b1101 | bignum_value)).nobits?(~(0b10 | bignum_value)).should == false
-    end
+  it "handles negative values using two's complement notation" do
+    (~0b1101).nobits?(0b1101).should == true
+    (-42).nobits?(-42).should == false
+    (~0b1101).nobits?(~0b10).should == false
+    (~(0b1101 | bignum_value)).nobits?(~(0b10 | bignum_value)).should == false
+  end
 
-    it "coerces the rhs using to_int" do
-      obj = mock("the int 0b10")
-      obj.should_receive(:to_int).and_return(0b10)
-      0b110.nobits?(obj).should == false
-    end
+  it "coerces the rhs using to_int" do
+    obj = mock("the int 0b10")
+    obj.should_receive(:to_int).and_return(0b10)
+    0b110.nobits?(obj).should == false
+  end
 
-    it "raises a TypeError when given a non-Integer" do
-      -> {
-        (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
-        13.nobits?(obj)
-      }.should raise_error(TypeError)
-      -> { 13.nobits?("10")    }.should raise_error(TypeError)
-      -> { 13.nobits?(:symbol) }.should raise_error(TypeError)
-    end
+  it "raises a TypeError when given a non-Integer" do
+    -> {
+      (obj = mock('10')).should_receive(:coerce).any_number_of_times.and_return([42,10])
+      13.nobits?(obj)
+    }.should.raise(TypeError)
+    -> { 13.nobits?("10")    }.should.raise(TypeError)
+    -> { 13.nobits?(:symbol) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/odd_spec.rb b/spec/ruby/core/integer/odd_spec.rb
index dd779fa44b..f9e50ec790 100644
--- a/spec/ruby/core/integer/odd_spec.rb
+++ b/spec/ruby/core/integer/odd_spec.rb
@@ -3,36 +3,36 @@ require_relative '../../spec_helper'
 describe "Integer#odd?" do
   context "fixnum" do
     it "returns true when self is an odd number" do
-      (-2).odd?.should be_false
-      (-1).odd?.should be_true
+      (-2).odd?.should == false
+      (-1).odd?.should == true
 
-      0.odd?.should be_false
-      1.odd?.should be_true
-      2.odd?.should be_false
+      0.odd?.should == false
+      1.odd?.should == true
+      2.odd?.should == false
 
-      bignum_value(0).odd?.should be_false
-      bignum_value(1).odd?.should be_true
+      bignum_value(0).odd?.should == false
+      bignum_value(1).odd?.should == true
 
-      (-bignum_value(0)).odd?.should be_false
-      (-bignum_value(1)).odd?.should be_true
+      (-bignum_value(0)).odd?.should == false
+      (-bignum_value(1)).odd?.should == true
     end
   end
 
   context "bignum" do
     it "returns true if self is odd and positive" do
-      (987279**19).odd?.should be_true
+      (987279**19).odd?.should == true
     end
 
     it "returns true if self is odd and negative" do
-      (-9873389**97).odd?.should be_true
+      (-9873389**97).odd?.should == true
     end
 
     it "returns false if self is even and positive" do
-      (10000000**10).odd?.should be_false
+      (10000000**10).odd?.should == false
     end
 
     it "returns false if self is even and negative" do
-      (-1000000**100).odd?.should be_false
+      (-1000000**100).odd?.should == false
     end
   end
 end
diff --git a/spec/ruby/core/integer/ord_spec.rb b/spec/ruby/core/integer/ord_spec.rb
index bcb57bea98..8b7dfe460d 100644
--- a/spec/ruby/core/integer/ord_spec.rb
+++ b/spec/ruby/core/integer/ord_spec.rb
@@ -2,16 +2,16 @@ require_relative '../../spec_helper'
 
 describe "Integer#ord" do
   it "returns self" do
-    20.ord.should eql(20)
-    40.ord.should eql(40)
+    20.ord.should.eql?(20)
+    40.ord.should.eql?(40)
 
-    0.ord.should eql(0)
-    (-10).ord.should eql(-10)
+    0.ord.should.eql?(0)
+    (-10).ord.should.eql?(-10)
 
-    ?a.ord.should eql(97)
-    ?Z.ord.should eql(90)
+    ?a.ord.should.eql?(97)
+    ?Z.ord.should.eql?(90)
 
-    bignum_value.ord.should eql(bignum_value)
-    (-bignum_value).ord.should eql(-bignum_value)
+    bignum_value.ord.should.eql?(bignum_value)
+    (-bignum_value).ord.should.eql?(-bignum_value)
   end
 end
diff --git a/spec/ruby/core/integer/plus_spec.rb b/spec/ruby/core/integer/plus_spec.rb
index 7e919a16db..b684377bd5 100644
--- a/spec/ruby/core/integer/plus_spec.rb
+++ b/spec/ruby/core/integer/plus_spec.rb
@@ -2,20 +2,14 @@ require_relative '../../spec_helper'
 require_relative 'shared/arithmetic_coerce'
 
 describe "Integer#+" do
-  ruby_version_is "2.4"..."2.5" do
-    it_behaves_like :integer_arithmetic_coerce_rescue, :+
-  end
-
-  ruby_version_is "2.5" do
-    it_behaves_like :integer_arithmetic_coerce_not_rescue, :+
-  end
+  it_behaves_like :integer_arithmetic_coerce_not_rescue, :+
 
   context "fixnum" do
     it "returns self plus the given Integer" do
       (491 + 2).should == 493
       (90210 + 10).should == 90220
 
-      (9 + bignum_value).should == 9223372036854775817
+      (9 + bignum_value).should == 18446744073709551625
       (1001 + 5.219).should == 1006.219
     end
 
@@ -23,9 +17,9 @@ describe "Integer#+" do
       -> {
         (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
         13 + obj
-      }.should raise_error(TypeError)
-      -> { 13 + "10"    }.should raise_error(TypeError)
-      -> { 13 + :symbol }.should raise_error(TypeError)
+      }.should.raise(TypeError)
+      -> { 13 + "10"    }.should.raise(TypeError)
+      -> { 13 + :symbol }.should.raise(TypeError)
     end
   end
 
@@ -35,15 +29,47 @@ describe "Integer#+" do
     end
 
     it "returns self plus the given Integer" do
-      (@bignum + 4).should == 9223372036854775888
-      (@bignum + 4.2).should be_close(9223372036854775888.2, TOLERANCE)
-      (@bignum + bignum_value(3)).should == 18446744073709551695
+      (@bignum + 4).should == 18446744073709551696
+      (@bignum + 4.2).should be_close(18446744073709551696.2, TOLERANCE)
+      (@bignum + bignum_value(3)).should == 36893488147419103311
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { @bignum + mock('10') }.should raise_error(TypeError)
-      -> { @bignum + "10" }.should raise_error(TypeError)
-      -> { @bignum + :symbol}.should raise_error(TypeError)
+      -> { @bignum + mock('10') }.should.raise(TypeError)
+      -> { @bignum + "10" }.should.raise(TypeError)
+      -> { @bignum + :symbol}.should.raise(TypeError)
     end
   end
+
+  it "can be redefined" do
+    code = <<~RUBY
+      class Integer
+        alias_method :old_plus, :+
+        def +(other)
+          self - other
+        end
+      end
+      result = 1 + 2
+      Integer.alias_method :+, :old_plus
+      print result
+    RUBY
+    ruby_exe(code).should == "-1"
+  end
+
+  it "coerces the RHS and calls #coerce" do
+    obj = mock("integer plus")
+    obj.should_receive(:coerce).with(6).and_return([6, 3])
+    (6 + obj).should == 9
+  end
+
+  it "coerces the RHS and calls #coerce even if it's private" do
+    obj = Object.new
+    class << obj
+      private def coerce(n)
+        [n, 3]
+      end
+    end
+
+    (6 + obj).should == 9
+  end
 end
diff --git a/spec/ruby/core/integer/pow_spec.rb b/spec/ruby/core/integer/pow_spec.rb
index ed14c40a27..12a3839c40 100644
--- a/spec/ruby/core/integer/pow_spec.rb
+++ b/spec/ruby/core/integer/pow_spec.rb
@@ -2,48 +2,50 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/exponent'
 
-ruby_version_is "2.5" do
-  describe "Integer#pow" do
-    context "one argument is passed" do
-      it_behaves_like :integer_exponent, :pow
+describe "Integer#pow" do
+  context "one argument is passed" do
+    it_behaves_like :integer_exponent, :pow
+  end
+
+  context "two arguments are passed" do
+    it "returns modulo of self raised to the given power" do
+      2.pow(5, 12).should == 8
+      2.pow(6, 13).should == 12
+      2.pow(7, 14).should == 2
+      2.pow(8, 15).should == 1
+    end
+
+    it "works well with bignums" do
+      2.pow(61, 5843009213693951).should.eql? 3697379018277258
+      2.pow(62, 5843009213693952).should.eql? 1551748822859776
+      2.pow(63, 5843009213693953).should.eql? 3103497645717974
+      2.pow(64, 5843009213693954).should.eql? 363986077738838
+    end
+
+    it "handles sign like #divmod does" do
+      2.pow(5, 12).should == 8
+      2.pow(5, -12).should == -4
+      -2.pow(5, 12).should == 4
+      -2.pow(5, -12).should == -8
+    end
+
+    it "ensures all arguments are integers" do
+      -> { 2.pow(5, 12.0) }.should.raise(TypeError, /2nd argument not allowed unless all arguments are integers/)
+      -> { 2.pow(5, Rational(12, 1)) }.should.raise(TypeError, /2nd argument not allowed unless all arguments are integers/)
+    end
+
+    it "raises TypeError for non-numeric value" do
+      -> { 2.pow(5, "12") }.should.raise(TypeError)
+      -> { 2.pow(5, []) }.should.raise(TypeError)
+      -> { 2.pow(5, nil) }.should.raise(TypeError)
+    end
+
+    it "raises a ZeroDivisionError when the given argument is 0" do
+      -> { 2.pow(5, 0) }.should.raise(ZeroDivisionError)
     end
 
-    context "two arguments are passed" do
-      it "returns modulo of self raised to the given power" do
-        2.pow(5, 12).should == 8
-        2.pow(6, 13).should == 12
-        2.pow(7, 14).should == 2
-        2.pow(8, 15).should == 1
-      end
-
-      it "works well with bignums" do
-        2.pow(61, 5843009213693951).should eql 3697379018277258
-        2.pow(62, 5843009213693952).should eql 1551748822859776
-        2.pow(63, 5843009213693953).should eql 3103497645717974
-        2.pow(64, 5843009213693954).should eql  363986077738838
-      end
-
-      it "handles sign like #divmod does" do
-         2.pow(5,  12).should ==  8
-         2.pow(5, -12).should == -4
-        -2.pow(5,  12).should ==  4
-        -2.pow(5, -12).should == -8
-      end
-
-      it "ensures all arguments are integers" do
-        -> { 2.pow(5, 12.0) }.should raise_error(TypeError, /2nd argument not allowed unless all arguments are integers/)
-        -> { 2.pow(5, Rational(12, 1)) }.should raise_error(TypeError, /2nd argument not allowed unless all arguments are integers/)
-      end
-
-      it "raises TypeError for non-numeric value" do
-        -> { 2.pow(5, "12") }.should raise_error(TypeError)
-        -> { 2.pow(5, []) }.should raise_error(TypeError)
-        -> { 2.pow(5, nil) }.should raise_error(TypeError)
-      end
-
-      it "raises a ZeroDivisionError when the given argument is 0" do
-        -> { 2.pow(5, 0) }.should raise_error(ZeroDivisionError)
-      end
+    it "raises a RangeError when the first argument is negative and the second argument is present" do
+      -> { 2.pow(-5, 1) }.should.raise(RangeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/pred_spec.rb b/spec/ruby/core/integer/pred_spec.rb
index 86750ebfd1..fce536b5a2 100644
--- a/spec/ruby/core/integer/pred_spec.rb
+++ b/spec/ruby/core/integer/pred_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Integer#pred" do
   it "returns the Integer equal to self - 1" do
-    0.pred.should eql(-1)
-    -1.pred.should eql(-2)
-    bignum_value.pred.should eql(bignum_value(-1))
-    fixnum_min.pred.should eql(fixnum_min - 1)
-    20.pred.should eql(19)
+    0.pred.should.eql?(-1)
+    -1.pred.should.eql?(-2)
+    bignum_value.pred.should.eql?(bignum_value(-1))
+    fixnum_min.pred.should.eql?(fixnum_min - 1)
+    20.pred.should.eql?(19)
   end
 end
diff --git a/spec/ruby/core/integer/rationalize_spec.rb b/spec/ruby/core/integer/rationalize_spec.rb
index 09d741af33..272eca6911 100644
--- a/spec/ruby/core/integer/rationalize_spec.rb
+++ b/spec/ruby/core/integer/rationalize_spec.rb
@@ -12,7 +12,7 @@ describe "Integer#rationalize" do
 
   it "returns a Rational object" do
     @numbers.each do |number|
-      number.rationalize.should be_an_instance_of(Rational)
+      number.rationalize.should.instance_of?(Rational)
     end
   end
 
@@ -33,7 +33,7 @@ describe "Integer#rationalize" do
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { 1.rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { 1.rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { 1.rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { 1.rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/integer/remainder_spec.rb b/spec/ruby/core/integer/remainder_spec.rb
index cd10dad6f2..deb81fb2a5 100644
--- a/spec/ruby/core/integer/remainder_spec.rb
+++ b/spec/ruby/core/integer/remainder_spec.rb
@@ -15,17 +15,17 @@ describe "Integer#remainder" do
     end
 
     it "keeps sign of self" do
-       5.remainder( 3).should ==  2
-       5.remainder(-3).should ==  2
+      5.remainder( 3).should == 2
+      5.remainder(-3).should == 2
       -5.remainder( 3).should == -2
       -5.remainder(-3).should == -2
     end
 
     it "raises TypeError if passed non-numeric argument" do
-      -> { 5.remainder("3") }.should raise_error(TypeError)
-      -> { 5.remainder(:"3") }.should raise_error(TypeError)
-      -> { 5.remainder([]) }.should raise_error(TypeError)
-      -> { 5.remainder(nil) }.should raise_error(TypeError)
+      -> { 5.remainder("3") }.should.raise(TypeError)
+      -> { 5.remainder(:"3") }.should.raise(TypeError)
+      -> { 5.remainder([]) }.should.raise(TypeError)
+      -> { 5.remainder(nil) }.should.raise(TypeError)
     end
   end
 
@@ -33,19 +33,19 @@ describe "Integer#remainder" do
     it "returns the remainder of dividing self by other" do
       a = bignum_value(79)
       a.remainder(2).should == 1
-      a.remainder(97.345).should be_close(46.5674996147722, TOLERANCE)
+      a.remainder(97.345).should be_close(93.1349992295444, TOLERANCE)
       a.remainder(bignum_value).should == 79
     end
 
     it "raises a ZeroDivisionError if other is zero and not a Float" do
-      -> { bignum_value(66).remainder(0) }.should raise_error(ZeroDivisionError)
+      -> { bignum_value(66).remainder(0) }.should.raise(ZeroDivisionError)
     end
 
     it "does raises ZeroDivisionError if other is zero and a Float" do
       a = bignum_value(7)
       b = bignum_value(32)
-      -> { a.remainder(0.0) }.should raise_error(ZeroDivisionError)
-      -> { b.remainder(-0.0) }.should raise_error(ZeroDivisionError)
+      -> { a.remainder(0.0) }.should.raise(ZeroDivisionError)
+      -> { b.remainder(-0.0) }.should.raise(ZeroDivisionError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/right_shift_spec.rb b/spec/ruby/core/integer/right_shift_spec.rb
index 3eeaf3eb2f..4281d3b7ab 100644
--- a/spec/ruby/core/integer/right_shift_spec.rb
+++ b/spec/ruby/core/integer/right_shift_spec.rb
@@ -52,48 +52,47 @@ describe "Integer#>> (with n >> m)" do
       (-7 >> 64).should == -1
     end
 
-    it "returns 0 when m is a bignum" do
-      (3 >> bignum_value).should == 0
-    end
-
-    it "returns an Bignum == fixnum_max * 2 when fixnum_max >> -1 and n > 0" do
+    it "returns a Bignum == fixnum_max * 2 when fixnum_max >> -1 and n > 0" do
       result = fixnum_max >> -1
-      result.should be_an_instance_of(Bignum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_max * 2
     end
 
-    it "returns an Bignum == fixnum_min * 2 when fixnum_min >> -1 and n < 0" do
+    it "returns a Bignum == fixnum_min * 2 when fixnum_min >> -1 and n < 0" do
       result = fixnum_min >> -1
-      result.should be_an_instance_of(Bignum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_min * 2
     end
 
     it "calls #to_int to convert the argument to an Integer" do
       obj = mock("2")
       obj.should_receive(:to_int).and_return(2)
-
       (8 >> obj).should == 2
+
+      obj = mock("to_int_bignum")
+      obj.should_receive(:to_int).and_return(bignum_value)
+      (8 >> obj).should == 0
     end
 
     it "raises a TypeError when #to_int does not return an Integer" do
       obj = mock("a string")
       obj.should_receive(:to_int).and_return("asdf")
 
-      -> { 3 >> obj }.should raise_error(TypeError)
+      -> { 3 >> obj }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed nil" do
-      -> { 3 >> nil }.should raise_error(TypeError)
+      -> { 3 >> nil }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed a String" do
-      -> { 3 >> "4" }.should raise_error(TypeError)
+      -> { 3 >> "4" }.should.raise(TypeError)
     end
   end
 
   context "bignum" do
     before :each do
-      @bignum = bignum_value * 16
+      @bignum = bignum_value * 8 # 2 ** 67
     end
 
     it "returns n shifted right m bits when n > 0, m > 0" do
@@ -150,19 +149,15 @@ describe "Integer#>> (with n >> m)" do
       (@bignum >> 68).should == 0
     end
 
-    it "returns 0 when m is a Bignum" do
-      (@bignum >> bignum_value).should == 0
-    end
-
     it "returns a Fixnum == fixnum_max when (fixnum_max * 2) >> 1 and n > 0" do
       result = (fixnum_max * 2) >> 1
-      result.should be_an_instance_of(Fixnum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_max
     end
 
     it "returns a Fixnum == fixnum_min when (fixnum_min * 2) >> 1 and n < 0" do
       result = (fixnum_min * 2) >> 1
-      result.should be_an_instance_of(Fixnum)
+      result.should.instance_of?(Integer)
       result.should == fixnum_min
     end
 
@@ -177,15 +172,62 @@ describe "Integer#>> (with n >> m)" do
       obj = mock("a string")
       obj.should_receive(:to_int).and_return("asdf")
 
-      -> { @bignum >> obj }.should raise_error(TypeError)
+      -> { @bignum >> obj }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed nil" do
-      -> { @bignum >> nil }.should raise_error(TypeError)
+      -> { @bignum >> nil }.should.raise(TypeError)
     end
 
     it "raises a TypeError when passed a String" do
-      -> { @bignum >> "4" }.should raise_error(TypeError)
+      -> { @bignum >> "4" }.should.raise(TypeError)
+    end
+  end
+
+  context "when m is a bignum or larger than int" do
+    it "returns -1 when m > 0 and n < 0" do
+      (-1 >> bignum_value).should == -1
+      (-1 >> (2**40)).should == -1
+
+      (-bignum_value >> bignum_value).should == -1
+      (-bignum_value >> (2**40)).should == -1
+    end
+
+    it "returns 0 when m > 0 and n >= 0" do
+      (0 >> bignum_value).should == 0
+      (1 >> bignum_value).should == 0
+      (bignum_value >> bignum_value).should == 0
+
+      (0 >> (2**40)).should == 0
+      (1 >> (2**40)).should == 0
+      (bignum_value >> (2**40)).should == 0
+    end
+
+    it "returns 0 when m < 0 long and n == 0" do
+      (0 >> -(2**40)).should == 0
+    end
+
+    it "returns 0 when m < 0 bignum and n == 0" do
+      (0 >> -bignum_value).should == 0
+    end
+
+    it "raises RangeError when m < 0 and n != 0" do
+      # https://bugs.ruby-lang.org/issues/18518#note-9
+      limit = RUBY_ENGINE == 'ruby' ? 2**67 : 2**32
+
+      coerce_long = mock("long")
+      coerce_long.stub!(:to_int).and_return(-limit)
+      coerce_bignum = mock("bignum")
+      coerce_bignum.stub!(:to_int).and_return(-bignum_value)
+      exps = [-limit, coerce_long]
+      exps << -bignum_value << coerce_bignum if bignum_value >= limit
+
+      exps.each { |exp|
+        -> { (1 >> exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (-1 >> exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (bignum_value >> exp) }.should.raise(RangeError, 'shift width too big')
+        -> { (-bignum_value >> exp) }.should.raise(RangeError, 'shift width too big')
+      }
     end
   end
 end
diff --git a/spec/ruby/core/integer/round_spec.rb b/spec/ruby/core/integer/round_spec.rb
index feb6d475d3..a3f11e7a76 100644
--- a/spec/ruby/core/integer/round_spec.rb
+++ b/spec/ruby/core/integer/round_spec.rb
@@ -6,49 +6,39 @@ describe "Integer#round" do
   it_behaves_like :integer_to_i, :round
   it_behaves_like :integer_rounding_positive_precision, :round
 
-  ruby_version_is ""..."2.5" do # Not just since 2.4
-    it "rounds itself as a float if passed a positive precision" do
-      [2, -4, 10**70, -10**100].each do |v|
-        v.round(42).should eql(v.to_f)
-      end
-    end
-  end
-
   # redmine:5228
   it "returns itself rounded if passed a negative value" do
-    +249.round(-2).should eql(+200)
-    -249.round(-2).should eql(-200)
-    (+25 * 10**70 - 1).round(-71).should eql(+20 * 10**70)
-    (-25 * 10**70 + 1).round(-71).should eql(-20 * 10**70)
+    +249.round(-2).should.eql?(+200)
+    -249.round(-2).should.eql?(-200)
+    (+25 * 10**70 - 1).round(-71).should.eql?(+20 * 10**70)
+    (-25 * 10**70 + 1).round(-71).should.eql?(-20 * 10**70)
   end
 
   it "returns itself rounded to nearest if passed a negative value" do
-    +250.round(-2).should eql(+300)
-    -250.round(-2).should eql(-300)
-    (+25 * 10**70).round(-71).should eql(+30 * 10**70)
-    (-25 * 10**70).round(-71).should eql(-30 * 10**70)
+    +250.round(-2).should.eql?(+300)
+    -250.round(-2).should.eql?(-300)
+    (+25 * 10**70).round(-71).should.eql?(+30 * 10**70)
+    (-25 * 10**70).round(-71).should.eql?(-30 * 10**70)
   end
 
-  platform_is_not wordsize: 32 do
-    it "raises a RangeError when passed a big negative value" do
-      -> { 42.round(fixnum_min) }.should raise_error(RangeError)
-    end
+  it "raises a RangeError when passed a big negative value" do
+    -> { 42.round(min_long - 1) }.should.raise(RangeError)
   end
 
   it "raises a RangeError when passed Float::INFINITY" do
-    -> { 42.round(Float::INFINITY) }.should raise_error(RangeError)
+    -> { 42.round(Float::INFINITY) }.should.raise(RangeError)
   end
 
   it "raises a RangeError when passed a beyond signed int" do
-    -> { 42.round(1<<31) }.should raise_error(RangeError)
+    -> { 42.round(1<<31) }.should.raise(RangeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { 42.round("4") }.should raise_error(TypeError)
+    -> { 42.round("4") }.should.raise(TypeError)
   end
 
   it "raises a TypeError when its argument cannot be converted to an Integer" do
-    -> { 42.round(nil) }.should raise_error(TypeError)
+    -> { 42.round(nil) }.should.raise(TypeError)
   end
 
   it "calls #to_int on the argument to convert it to an Integer" do
@@ -60,42 +50,32 @@ describe "Integer#round" do
   it "raises a TypeError when #to_int does not return an Integer" do
     obj = mock("Object")
     obj.stub!(:to_int).and_return([])
-    -> { 42.round(obj) }.should raise_error(TypeError)
+    -> { 42.round(obj) }.should.raise(TypeError)
   end
 
   it "returns different rounded values depending on the half option" do
-    25.round(-1, half: :up).should      eql(30)
-    25.round(-1, half: :down).should    eql(20)
-    25.round(-1, half: :even).should    eql(20)
-    25.round(-1, half: nil).should      eql(30)
-    35.round(-1, half: :up).should      eql(40)
-    35.round(-1, half: :down).should    eql(30)
-    35.round(-1, half: :even).should    eql(40)
-    35.round(-1, half: nil).should      eql(40)
-    (-25).round(-1, half: :up).should   eql(-30)
-    (-25).round(-1, half: :down).should eql(-20)
-    (-25).round(-1, half: :even).should eql(-20)
-    (-25).round(-1, half: nil).should   eql(-30)
-  end
-
-  ruby_version_is "2.4"..."2.5" do
-    it "returns itself as a float if passed a positive precision and the half option" do
-      35.round(1, half: :up).should      eql(35.0)
-      35.round(1, half: :down).should    eql(35.0)
-      35.round(1, half: :even).should    eql(35.0)
-    end
+    25.round(-1, half: :up).should.eql?(30)
+    25.round(-1, half: :down).should.eql?(20)
+    25.round(-1, half: :even).should.eql?(20)
+    25.round(-1, half: nil).should.eql?(30)
+    35.round(-1, half: :up).should.eql?(40)
+    35.round(-1, half: :down).should.eql?(30)
+    35.round(-1, half: :even).should.eql?(40)
+    35.round(-1, half: nil).should.eql?(40)
+    (-25).round(-1, half: :up).should.eql?(-30)
+    (-25).round(-1, half: :down).should.eql?(-20)
+    (-25).round(-1, half: :even).should.eql?(-20)
+    (-25).round(-1, half: nil).should.eql?(-30)
   end
 
-  ruby_version_is "2.5" do
-    it "returns itself if passed a positive precision and the half option" do
-      35.round(1, half: :up).should      eql(35)
-      35.round(1, half: :down).should    eql(35)
-      35.round(1, half: :even).should    eql(35)
-    end
+  it "returns itself if passed a positive precision and the half option" do
+    35.round(1, half: :up).should.eql?(35)
+    35.round(1, half: :down).should.eql?(35)
+    35.round(1, half: :even).should.eql?(35)
   end
 
   it "raises ArgumentError for an unknown rounding mode" do
-    -> { 42.round(-1, half: :foo) }.should raise_error(ArgumentError, /invalid rounding mode: foo/)
-    -> { 42.round(1, half: :foo) }.should raise_error(ArgumentError, /invalid rounding mode: foo/)
+    -> { 42.round(-1, half: :foo) }.should.raise(ArgumentError, /invalid rounding mode: foo/)
+    -> { 42.round(1, half: :foo) }.should.raise(ArgumentError, /invalid rounding mode: foo/)
   end
 end
diff --git a/spec/ruby/core/integer/shared/abs.rb b/spec/ruby/core/integer/shared/abs.rb
index 946aa21864..43844c9065 100644
--- a/spec/ruby/core/integer/shared/abs.rb
+++ b/spec/ruby/core/integer/shared/abs.rb
@@ -11,8 +11,8 @@ describe :integer_abs, shared: true do
 
   context "bignum" do
     it "returns the absolute bignum value" do
-      bignum_value(39).send(@method).should == 9223372036854775847
-      (-bignum_value(18)).send(@method).should == 9223372036854775826
+      bignum_value(39).send(@method).should == 18446744073709551655
+      (-bignum_value(18)).send(@method).should == 18446744073709551634
     end
   end
 end
diff --git a/spec/ruby/core/integer/shared/arithmetic_coerce.rb b/spec/ruby/core/integer/shared/arithmetic_coerce.rb
index 4c0cbcb999..561b18fe52 100644
--- a/spec/ruby/core/integer/shared/arithmetic_coerce.rb
+++ b/spec/ruby/core/integer/shared/arithmetic_coerce.rb
@@ -1,31 +1,11 @@
 require_relative '../fixtures/classes'
 
-describe :integer_arithmetic_coerce_rescue, shared: true do
-  it "rescues exception (StandardError and subclasses) raised in other#coerce and raises TypeError" do
-    b = mock("numeric with failed #coerce")
-    b.should_receive(:coerce).and_raise(IntegerSpecs::CoerceError)
-
-    # e.g. 1 + b
-    -> { 1.send(@method, b) }.should raise_error(TypeError, /MockObject can't be coerced into Integer/)
-  end
-
-  it "does not rescue Exception and StandardError siblings raised in other#coerce" do
-    [Exception, NoMemoryError].each do |exception|
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(exception)
-
-      # e.g. 1 + b
-      -> { 1.send(@method, b) }.should raise_error(exception)
-    end
-  end
-end
-
 describe :integer_arithmetic_coerce_not_rescue, shared: true do
   it "does not rescue exception raised in other#coerce" do
     b = mock("numeric with failed #coerce")
     b.should_receive(:coerce).and_raise(IntegerSpecs::CoerceError)
 
     # e.g. 1 + b
-    -> { 1.send(@method, b) }.should raise_error(IntegerSpecs::CoerceError)
+    -> { 1.send(@method, b) }.should.raise(IntegerSpecs::CoerceError)
   end
 end
diff --git a/spec/ruby/core/integer/shared/comparison_coerce.rb b/spec/ruby/core/integer/shared/comparison_coerce.rb
index 50437f77f5..4bb7404183 100644
--- a/spec/ruby/core/integer/shared/comparison_coerce.rb
+++ b/spec/ruby/core/integer/shared/comparison_coerce.rb
@@ -1,33 +1,11 @@
 require_relative '../fixtures/classes'
 
-describe :integer_comparison_coerce_rescue, shared: true do
-  it "rescues exception (StandardError and subclasses) raised in other#coerce and raises ArgumentError" do
-    b = mock("numeric with failed #coerce")
-    b.should_receive(:coerce).and_raise(IntegerSpecs::CoerceError)
-
-    # e.g. 1 > b
-    -> {
-      -> { 1.send(@method, b) }.should raise_error(ArgumentError, /comparison of Integer with MockObject failed/)
-    }.should complain(/Numerical comparison operators will no more rescue exceptions of #coerce/)
-  end
-
-  it "does not rescue Exception and StandardError siblings raised in other#coerce" do
-    [Exception, NoMemoryError].each do |exception|
-      b = mock("numeric with failed #coerce")
-      b.should_receive(:coerce).and_raise(exception)
-
-      # e.g. 1 > b
-      -> { 1.send(@method, b) }.should raise_error(exception)
-    end
-  end
-end
-
 describe :integer_comparison_coerce_not_rescue, shared: true do
   it "does not rescue exception raised in other#coerce" do
     b = mock("numeric with failed #coerce")
     b.should_receive(:coerce).and_raise(IntegerSpecs::CoerceError)
 
     # e.g. 1 > b
-    -> { 1.send(@method, b) }.should raise_error(IntegerSpecs::CoerceError)
+    -> { 1.send(@method, b) }.should.raise(IntegerSpecs::CoerceError)
   end
 end
diff --git a/spec/ruby/core/integer/shared/equal.rb b/spec/ruby/core/integer/shared/equal.rb
index 03416b60f5..c621ba3f81 100644
--- a/spec/ruby/core/integer/shared/equal.rb
+++ b/spec/ruby/core/integer/shared/equal.rb
@@ -4,14 +4,14 @@ describe :integer_equal, shared: true do
       1.send(@method, 1).should == true
       9.send(@method, 5).should == false
 
-      # Actually, these call Float#==, Bignum#== etc.
+      # Actually, these call Float#==, Integer#== etc.
       9.send(@method, 9.0).should == true
       9.send(@method, 9.01).should == false
 
       10.send(@method, bignum_value).should == false
     end
 
-    it "calls 'other == self' if the given argument is not a Integer" do
+    it "calls 'other == self' if the given argument is not an Integer" do
       1.send(@method, '*').should == false
 
       obj = mock('one other')
@@ -54,5 +54,10 @@ describe :integer_equal, shared: true do
       @bignum.send(@method, obj).should == true
       @bignum.send(@method, obj).should == false
     end
+
+    it "does not lose precision when comparing with a Float" do
+      (bignum_value(1).send(@method, bignum_value.to_f)).should == false
+      (bignum_value.send(@method, bignum_value.to_f)).should == true
+    end
   end
 end
diff --git a/spec/ruby/core/integer/shared/exponent.rb b/spec/ruby/core/integer/shared/exponent.rb
index f292cc2448..0be13859f9 100644
--- a/spec/ruby/core/integer/shared/exponent.rb
+++ b/spec/ruby/core/integer/shared/exponent.rb
@@ -1,58 +1,78 @@
 describe :integer_exponent, shared: true do
   context "fixnum" do
     it "returns self raised to the given power" do
-      2.send(@method, 0).should eql 1
-      2.send(@method, 1).should eql 2
-      2.send(@method, 2).should eql 4
+      2.send(@method, 0).should.eql? 1
+      2.send(@method, 1).should.eql? 2
+      2.send(@method, 2).should.eql? 4
 
-      9.send(@method, 0.5).should eql 3.0
-      9.send(@method, Rational(1, 2)).should eql 3.0
+      9.send(@method, 0.5).should.eql? 3.0
+      9.send(@method, Rational(1, 2)).should.eql? 3.0
       5.send(@method, -1).to_f.to_s.should == '0.2'
 
-      2.send(@method, 40).should eql 1099511627776
+      2.send(@method, 40).should.eql? 1099511627776
     end
 
     it "overflows the answer to a bignum transparently" do
-      2.send(@method, 29).should eql 536870912
-      2.send(@method, 30).should eql 1073741824
-      2.send(@method, 31).should eql 2147483648
-      2.send(@method, 32).should eql 4294967296
+      2.send(@method, 29).should.eql? 536870912
+      2.send(@method, 30).should.eql? 1073741824
+      2.send(@method, 31).should.eql? 2147483648
+      2.send(@method, 32).should.eql? 4294967296
 
-      2.send(@method, 61).should eql 2305843009213693952
-      2.send(@method, 62).should eql 4611686018427387904
-      2.send(@method, 63).should eql 9223372036854775808
-      2.send(@method, 64).should eql 18446744073709551616
-      8.send(@method, 23).should eql 590295810358705651712
+      2.send(@method, 61).should.eql? 2305843009213693952
+      2.send(@method, 62).should.eql? 4611686018427387904
+      2.send(@method, 63).should.eql? 9223372036854775808
+      2.send(@method, 64).should.eql? 18446744073709551616
+      8.send(@method, 23).should.eql? 590295810358705651712
     end
 
     it "raises negative numbers to the given power" do
-      (-2).send(@method, 29).should eql(-536870912)
-      (-2).send(@method, 30).should eql(1073741824)
-      (-2).send(@method, 31).should eql(-2147483648)
-      (-2).send(@method, 32).should eql(4294967296)
+      (-2).send(@method, 29).should.eql?(-536870912)
+      (-2).send(@method, 30).should.eql?(1073741824)
+      (-2).send(@method, 31).should.eql?(-2147483648)
+      (-2).send(@method, 32).should.eql?(4294967296)
+      (-2).send(@method, 33).should.eql?(-8589934592)
 
-      (-2).send(@method, 61).should eql(-2305843009213693952)
-      (-2).send(@method, 62).should eql(4611686018427387904)
-      (-2).send(@method, 63).should eql(-9223372036854775808)
-      (-2).send(@method, 64).should eql(18446744073709551616)
+      (-2).send(@method, 61).should.eql?(-2305843009213693952)
+      (-2).send(@method, 62).should.eql?(4611686018427387904)
+      (-2).send(@method, 63).should.eql?(-9223372036854775808)
+      (-2).send(@method, 64).should.eql?(18446744073709551616)
+      (-2).send(@method, 65).should.eql?(-36893488147419103232)
     end
 
     it "can raise 1 to a bignum safely" do
-      1.send(@method, 4611686018427387904).should eql 1
+      1.send(@method, 4611686018427387904).should.eql? 1
     end
 
     it "can raise -1 to a bignum safely" do
-      (-1).send(@method, 4611686018427387904).should eql(1)
-      (-1).send(@method, 4611686018427387905).should eql(-1)
+      (-1).send(@method, 4611686018427387904).should.eql?(1)
+      (-1).send(@method, 4611686018427387905).should.eql?(-1)
     end
 
-    it "returns Float::INFINITY when the number is too big" do
-      2.send(@method, 427387904).should == Float::INFINITY
+    ruby_version_is ""..."3.4" do
+      it "returns Float::INFINITY when the number is too big" do
+        -> {
+          2.send(@method, 427387904).should == Float::INFINITY
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "returns an Integer for results larger than the old 32MB limit" do
+        # 2 ** 40000000 requires 40000001 bits
+        # This exceeds the old 32MB limit but is within the new 16GB limit
+        result = 2.send(@method, 40000000)
+        result.should.is_a?(Integer)
+        result.bit_length.should == 40000001
+      end
+
+      it "raises an ArgumentError when the result size exceeds the limit" do
+        -> { 100000000.send(@method, 1000000000) }.should.raise(ArgumentError)
+      end
     end
 
     it "raises a ZeroDivisionError for 0 ** -1" do
-      -> { 0.send(@method, -1) }.should raise_error(ZeroDivisionError)
-      -> { 0.send(@method, Rational(-1, 1)) }.should raise_error(ZeroDivisionError)
+      -> { 0.send(@method, -1) }.should.raise(ZeroDivisionError)
+      -> { 0.send(@method, Rational(-1, 1)) }.should.raise(ZeroDivisionError)
     end
 
     it "returns Float::INFINITY for 0 ** -1.0" do
@@ -60,9 +80,9 @@ describe :integer_exponent, shared: true do
     end
 
     it "raises a TypeError when given a non-numeric power" do
-      -> { 13.send(@method, "10") }.should raise_error(TypeError)
-      -> { 13.send(@method, :symbol) }.should raise_error(TypeError)
-      -> { 13.send(@method, nil) }.should raise_error(TypeError)
+      -> { 13.send(@method, "10") }.should.raise(TypeError)
+      -> { 13.send(@method, :symbol) }.should.raise(TypeError)
+      -> { 13.send(@method, nil) }.should.raise(TypeError)
     end
 
     it "coerces power and calls #**" do
@@ -94,25 +114,49 @@ describe :integer_exponent, shared: true do
     end
 
     it "returns self raised to other power" do
-      (@bignum.send(@method, 4)).should == 7237005577332262361485077344629993318496048279512298547155833600056910050625
-      (@bignum.send(@method, 1.2)).should be_close(57262152889751597425762.57804, TOLERANCE)
+      (@bignum.send(@method, 4)).should == 115792089237316196603666111261383895964500887398800252671052694326794607293761
+      (@bignum.send(@method, 1.3)).should be_close(11109528802438156839288832.0, TOLERANCE)
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { @bignum.send(@method, mock('10')) }.should raise_error(TypeError)
-      -> { @bignum.send(@method, "10") }.should raise_error(TypeError)
-      -> { @bignum.send(@method, :symbol) }.should raise_error(TypeError)
-    end
-
-    it "switch to a Float when the values is too big" do
-      flt = @bignum.send(@method, @bignum)
-      flt.should be_kind_of(Float)
-      flt.infinite?.should == 1
+      -> { @bignum.send(@method, mock('10')) }.should.raise(TypeError)
+      -> { @bignum.send(@method, "10") }.should.raise(TypeError)
+      -> { @bignum.send(@method, :symbol) }.should.raise(TypeError)
+    end
+
+    ruby_version_is ""..."3.4" do
+      it "switch to a Float when the values is too big" do
+        flt = nil
+        -> {
+          flt = @bignum.send(@method, @bignum)
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+        flt.should.is_a?(Float)
+        flt.infinite?.should == 1
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "returns an Integer for large Bignum results exceeding the old limit" do
+        # (2 ** 70) ** 500000 requires 35000001 bits
+        # This exceeds the old 32MB limit but is within the new 16GB limit
+        bignum_base = 2 ** 70
+        result = bignum_base.send(@method, 500000)
+        result.should.is_a?(Integer)
+        result.bit_length.should == 35000001
+      end
+
+      it "raises an ArgumentError when Bignum result exceeds the limit" do
+        # @bignum ** @bignum would require enormous memory
+        -> {
+          @bignum.send(@method, @bignum)
+        }.should.raise(ArgumentError)
+      end
     end
 
     it "returns a complex number when negative and raised to a fractional power" do
-      ((-@bignum).send(@method, (1.0/3)))      .should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
-      ((-@bignum).send(@method, Rational(1,3))).should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
+      (-bignum_value).send(@method, (1.0/2)).should be_close(Complex(0.0, 4294967296.0), TOLERANCE)
+      (-@bignum).send(@method, (1.0/3))      .should be_close(Complex(1321122.9748145656, 2288252.1154253655), TOLERANCE)
+      (-@bignum).send(@method, Rational(1,3)).should be_close(Complex(1321122.9748145656, 2288252.1154253655), TOLERANCE)
     end
   end
 end
diff --git a/spec/ruby/core/integer/shared/integer_ceil_precision.rb b/spec/ruby/core/integer/shared/integer_ceil_precision.rb
new file mode 100644
index 0000000000..b23c17937f
--- /dev/null
+++ b/spec/ruby/core/integer/shared/integer_ceil_precision.rb
@@ -0,0 +1,54 @@
+describe :integer_ceil_precision, shared: true do
+  context "precision is zero" do
+    it "returns Integer equal to self" do
+      send(@method, 0).ceil(0).should.eql?(0)
+      send(@method, 123).ceil(0).should.eql?(123)
+      send(@method, -123).ceil(0).should.eql?(-123)
+    end
+  end
+
+  context "precision is positive" do
+    it "returns self" do
+      send(@method, 0).ceil(1).should.eql?(send(@method, 0))
+      send(@method, 0).ceil(10).should.eql?(send(@method, 0))
+
+      send(@method, 123).ceil(10).should.eql?(send(@method, 123))
+      send(@method, -123).ceil(10).should.eql?(send(@method, -123))
+    end
+  end
+
+  context "precision is negative" do
+    it "always returns 0 when self is 0" do
+      send(@method, 0).ceil(-1).should.eql?(0)
+      send(@method, 0).ceil(-10).should.eql?(0)
+    end
+
+    it "returns Integer equal to self if there are already at least precision.abs trailing zeros" do
+      send(@method, 10).ceil(-1).should.eql?(10)
+      send(@method, 100).ceil(-1).should.eql?(100)
+      send(@method, 100).ceil(-2).should.eql?(100)
+      send(@method, -10).ceil(-1).should.eql?(-10)
+      send(@method, -100).ceil(-1).should.eql?(-100)
+      send(@method, -100).ceil(-2).should.eql?(-100)
+    end
+
+    it "returns smallest Integer greater than self with at least precision.abs trailing zeros" do
+      send(@method, 123).ceil(-1).should.eql?(130)
+      send(@method, 123).ceil(-2).should.eql?(200)
+      send(@method, 123).ceil(-3).should.eql?(1000)
+
+      send(@method, -123).ceil(-1).should.eql?(-120)
+      send(@method, -123).ceil(-2).should.eql?(-100)
+      send(@method, -123).ceil(-3).should.eql?(0)
+
+      send(@method, 100).ceil(-3).should.eql?(1000)
+      send(@method, -100).ceil(-3).should.eql?(0)
+    end
+
+    # Bug #20654
+    it "returns 10**precision.abs when precision.abs has more digits than self" do
+      send(@method, 123).ceil(-20).should.eql?(100000000000000000000)
+      send(@method, 123).ceil(-50).should.eql?(100000000000000000000000000000000000000000000000000)
+    end
+  end
+end
diff --git a/spec/ruby/core/integer/shared/integer_floor_precision.rb b/spec/ruby/core/integer/shared/integer_floor_precision.rb
new file mode 100644
index 0000000000..6247907d4c
--- /dev/null
+++ b/spec/ruby/core/integer/shared/integer_floor_precision.rb
@@ -0,0 +1,42 @@
+describe :integer_floor_precision, shared: true do
+  context "precision is zero" do
+    it "returns integer self" do
+      send(@method, 0).floor(0).should.eql?(0)
+      send(@method, 123).floor(0).should.eql?(123)
+      send(@method, -123).floor(0).should.eql?(-123)
+    end
+  end
+
+  context "precision is positive" do
+    it "returns self" do
+      send(@method, 0).floor(1).should.eql?(send(@method, 0))
+      send(@method, 0).floor(10).should.eql?(send(@method, 0))
+
+      send(@method, 123).floor(10).should.eql?(send(@method, 123))
+      send(@method, -123).floor(10).should.eql?(send(@method, -123))
+    end
+  end
+
+  context "precision is negative" do
+    it "always returns 0 when self is 0" do
+      send(@method, 0).floor(-1).should.eql?(0)
+      send(@method, 0).floor(-10).should.eql?(0)
+    end
+
+    it "returns largest integer less than self with at least precision.abs trailing zeros" do
+      send(@method, 123).floor(-1).should.eql?(120)
+      send(@method, 123).floor(-2).should.eql?(100)
+      send(@method, 123).floor(-3).should.eql?(0)
+
+      send(@method, -123).floor(-1).should.eql?(-130)
+      send(@method, -123).floor(-2).should.eql?(-200)
+      send(@method, -123).floor(-3).should.eql?(-1000)
+    end
+
+    # Bug #20654
+    it "returns -(10**precision.abs) when self is negative and precision.abs is larger than the number digits of self" do
+      send(@method, -123).floor(-20).should.eql?(-100000000000000000000)
+      send(@method, -123).floor(-50).should.eql?(-100000000000000000000000000000000000000000000000000)
+    end
+  end
+end
diff --git a/spec/ruby/core/integer/shared/integer_rounding.rb b/spec/ruby/core/integer/shared/integer_rounding.rb
index 3fb6e830ef..92f2a2327c 100644
--- a/spec/ruby/core/integer/shared/integer_rounding.rb
+++ b/spec/ruby/core/integer/shared/integer_rounding.rb
@@ -1,29 +1,19 @@
 describe :integer_rounding_positive_precision, shared: true do
   it "returns self if not passed a precision" do
     [2, -4, 10**70, -10**100].each do |v|
-      v.send(@method).should eql(v)
+      v.send(@method).should.eql?(v)
     end
   end
 
   it "returns self if passed a precision of zero" do
     [2, -4, 10**70, -10**100].each do |v|
-      v.send(@method, 0).should eql(v)
+      v.send(@method, 0).should.eql?(v)
     end
   end
 
-  ruby_version_is "2.4"..."2.5" do
-    it "returns itself as a float if passed a positive precision" do
-      [2, -4, 10**70, -10**100].each do |v|
-        v.send(@method, 42).should eql(v.to_f)
-      end
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "returns itself if passed a positive precision" do
-      [2, -4, 10**70, -10**100].each do |v|
-        v.send(@method, 42).should eql(v)
-      end
+  it "returns itself if passed a positive precision" do
+    [2, -4, 10**70, -10**100].each do |v|
+      v.send(@method, 42).should.eql?(v)
     end
   end
 end
diff --git a/spec/ruby/core/integer/shared/modulo.rb b/spec/ruby/core/integer/shared/modulo.rb
index b06d81e17d..d0b5e26ed5 100644
--- a/spec/ruby/core/integer/shared/modulo.rb
+++ b/spec/ruby/core/integer/shared/modulo.rb
@@ -1,6 +1,12 @@
 describe :integer_modulo, shared: true do
   context "fixnum" do
     it "returns the modulus obtained from dividing self by the given argument" do
+      # test all possible combinations:
+      # - integer/double/bignum argument
+      # - positive/negative argument
+      # - positive/negative self
+      # - self greater/smaller than argument
+
       13.send(@method, 4).should == 1
       4.send(@method, 13).should == 4
 
@@ -16,59 +22,93 @@ describe :integer_modulo, shared: true do
       (200).send(@method, -256).should == -56
       (1000).send(@method, -512).should == -24
 
+      13.send(@method, -4.0).should == -3.0
+      4.send(@method, -13.0).should == -9.0
+
+      -13.send(@method, -4.0).should == -1.0
+      -4.send(@method, -13.0).should == -4.0
+
+      -13.send(@method, 4.0).should == 3.0
+      -4.send(@method, 13.0).should == 9.0
+
       1.send(@method, 2.0).should == 1.0
       200.send(@method, bignum_value).should == 200
+
+      4.send(@method, bignum_value(10)).should == 4
+      4.send(@method, -bignum_value(10)).should == -18446744073709551622
+      -4.send(@method, bignum_value(10)).should == 18446744073709551622
+      -4.send(@method, -bignum_value(10)).should == -4
     end
 
     it "raises a ZeroDivisionError when the given argument is 0" do
-      -> { 13.send(@method, 0)  }.should raise_error(ZeroDivisionError)
-      -> { 0.send(@method, 0)   }.should raise_error(ZeroDivisionError)
-      -> { -10.send(@method, 0) }.should raise_error(ZeroDivisionError)
+      -> { 13.send(@method, 0)  }.should.raise(ZeroDivisionError)
+      -> { 0.send(@method, 0)   }.should.raise(ZeroDivisionError)
+      -> { -10.send(@method, 0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and a Float" do
-      -> { 0.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
-      -> { 10.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
-      -> { -10.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
+      -> { 0.send(@method, 0.0) }.should.raise(ZeroDivisionError)
+      -> { 10.send(@method, 0.0) }.should.raise(ZeroDivisionError)
+      -> { -10.send(@method, 0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when given a non-Integer" do
       -> {
         (obj = mock('10')).should_receive(:to_int).any_number_of_times.and_return(10)
         13.send(@method, obj)
-      }.should raise_error(TypeError)
-      -> { 13.send(@method, "10")    }.should raise_error(TypeError)
-      -> { 13.send(@method, :symbol) }.should raise_error(TypeError)
+      }.should.raise(TypeError)
+      -> { 13.send(@method, "10")    }.should.raise(TypeError)
+      -> { 13.send(@method, :symbol) }.should.raise(TypeError)
     end
   end
 
   context "bignum" do
     before :each do
-      @bignum = bignum_value
+      @bignum = bignum_value(10)
     end
 
     it "returns the modulus obtained from dividing self by the given argument" do
-      @bignum.send(@method, 5).should == 3
-      @bignum.send(@method, -5).should == -2
-      @bignum.send(@method, -100).should == -92
-      @bignum.send(@method, 2.22).should be_close(0.780180180180252, TOLERANCE)
-      @bignum.send(@method, bignum_value(10)).should == 9223372036854775808
+      # test all possible combinations:
+      # - integer/double/bignum argument
+      # - positive/negative argument
+      # - positive/negative self
+      # - self greater/smaller than argument
+
+      @bignum.send(@method, 5).should == 1
+      @bignum.send(@method, -5).should == -4
+      (-@bignum).send(@method, 5).should == 4
+      (-@bignum).send(@method, -5).should == -1
+
+      @bignum.send(@method, 2.22).should be_close(1.5603603603605034, TOLERANCE)
+      @bignum.send(@method, -2.22).should be_close(-0.6596396396394968, TOLERANCE)
+      (-@bignum).send(@method, 2.22).should be_close(0.6596396396394968, TOLERANCE)
+      (-@bignum).send(@method, -2.22).should be_close(-1.5603603603605034, TOLERANCE)
+
+      @bignum.send(@method, @bignum + 10).should == 18446744073709551626
+      @bignum.send(@method, -(@bignum + 10)).should == -10
+      (-@bignum).send(@method, @bignum + 10).should == 10
+      (-@bignum).send(@method, -(@bignum + 10)).should == -18446744073709551626
+
+      (@bignum + 10).send(@method, @bignum).should == 10
+      (@bignum + 10).send(@method, -@bignum).should == -18446744073709551616
+      (-(@bignum + 10)).send(@method, @bignum).should == 18446744073709551616
+      (-(@bignum + 10)).send(@method, -@bignum).should == -10
     end
 
     it "raises a ZeroDivisionError when the given argument is 0" do
-      -> { @bignum.send(@method, 0) }.should raise_error(ZeroDivisionError)
-      -> { (-@bignum).send(@method, 0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.send(@method, 0) }.should.raise(ZeroDivisionError)
+      -> { (-@bignum).send(@method, 0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a ZeroDivisionError when the given argument is 0 and a Float" do
-      -> { @bignum.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
-      -> { -@bignum.send(@method, 0.0) }.should raise_error(ZeroDivisionError)
+      -> { @bignum.send(@method, 0.0) }.should.raise(ZeroDivisionError)
+      -> { -@bignum.send(@method, 0.0) }.should.raise(ZeroDivisionError)
     end
 
     it "raises a TypeError when given a non-Integer" do
-      -> { @bignum.send(@method, mock('10')) }.should raise_error(TypeError)
-      -> { @bignum.send(@method, "10") }.should raise_error(TypeError)
-      -> { @bignum.send(@method, :symbol) }.should raise_error(TypeError)
+      -> { @bignum.send(@method, mock('10')) }.should.raise(TypeError)
+      -> { @bignum.send(@method, "10") }.should.raise(TypeError)
+      -> { @bignum.send(@method, :symbol) }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/integer/shared/to_i.rb b/spec/ruby/core/integer/shared/to_i.rb
index 7b974cd3a7..2b6a50484a 100644
--- a/spec/ruby/core/integer/shared/to_i.rb
+++ b/spec/ruby/core/integer/shared/to_i.rb
@@ -1,8 +1,8 @@
 describe :integer_to_i, shared: true do
   it "returns self" do
-    10.send(@method).should eql(10)
-    (-15).send(@method).should eql(-15)
-    bignum_value.send(@method).should eql(bignum_value)
-    (-bignum_value).send(@method).should eql(-bignum_value)
+    10.send(@method).should.eql?(10)
+    (-15).send(@method).should.eql?(-15)
+    bignum_value.send(@method).should.eql?(bignum_value)
+    (-bignum_value).send(@method).should.eql?(-bignum_value)
   end
 end
diff --git a/spec/ruby/core/integer/size_spec.rb b/spec/ruby/core/integer/size_spec.rb
index a134e82384..725e9eb062 100644
--- a/spec/ruby/core/integer/size_spec.rb
+++ b/spec/ruby/core/integer/size_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Integer#size" do
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     it "returns the number of bytes in the machine representation of self" do
       -1.size.should == 4
       0.size.should == 4
@@ -9,7 +9,7 @@ describe "Integer#size" do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     it "returns the number of bytes in the machine representation of self" do
       -1.size.should == 8
       0.size.should == 8
diff --git a/spec/ruby/core/integer/sqrt_spec.rb b/spec/ruby/core/integer/sqrt_spec.rb
index e56da058a0..bf90ea747e 100644
--- a/spec/ruby/core/integer/sqrt_spec.rb
+++ b/spec/ruby/core/integer/sqrt_spec.rb
@@ -1,33 +1,31 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  describe "Integer.sqrt" do
-    it "returns an integer" do
-      Integer.sqrt(10).should be_kind_of(Integer)
-    end
+describe "Integer.sqrt" do
+  it "returns an integer" do
+    Integer.sqrt(10).should.is_a?(Integer)
+  end
 
-    it "returns the integer square root of the argument" do
-      Integer.sqrt(0).should == 0
-      Integer.sqrt(1).should == 1
-      Integer.sqrt(24).should == 4
-      Integer.sqrt(25).should == 5
-      Integer.sqrt(10**400).should == 10**200
-    end
+  it "returns the integer square root of the argument" do
+    Integer.sqrt(0).should == 0
+    Integer.sqrt(1).should == 1
+    Integer.sqrt(24).should == 4
+    Integer.sqrt(25).should == 5
+    Integer.sqrt(10**400).should == 10**200
+  end
 
-    it "raises a Math::DomainError if the argument is negative" do
-      -> { Integer.sqrt(-4) }.should raise_error(Math::DomainError)
-    end
+  it "raises a Math::DomainError if the argument is negative" do
+    -> { Integer.sqrt(-4) }.should.raise(Math::DomainError)
+  end
 
-    it "accepts any argument that can be coerced to Integer" do
-      Integer.sqrt(10.0).should == 3
-    end
+  it "accepts any argument that can be coerced to Integer" do
+    Integer.sqrt(10.0).should == 3
+  end
 
-    it "converts the argument with #to_int" do
-      Integer.sqrt(mock_int(10)).should == 3
-    end
+  it "converts the argument with #to_int" do
+    Integer.sqrt(mock_int(10)).should == 3
+  end
 
-    it "raises a TypeError if the argument cannot be coerced to Integer" do
-      -> { Integer.sqrt("test") }.should raise_error(TypeError)
-    end
+  it "raises a TypeError if the argument cannot be coerced to Integer" do
+    -> { Integer.sqrt("test") }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/integer/to_f_spec.rb b/spec/ruby/core/integer/to_f_spec.rb
index 06092eaa92..0681236095 100644
--- a/spec/ruby/core/integer/to_f_spec.rb
+++ b/spec/ruby/core/integer/to_f_spec.rb
@@ -11,9 +11,9 @@ describe "Integer#to_f" do
 
   context "bignum" do
     it "returns self converted to a Float" do
-      bignum_value(0x4000_0aa0_0bb0_0000).to_f.should eql(13_835_069_737_789_292_544.00)
-      bignum_value(0x8000_0000_0000_0ccc).to_f.should eql(18_446_744_073_709_555_712.00)
-      (-bignum_value(99)).to_f.should eql(-9_223_372_036_854_775_808.00)
+      bignum_value(0x4000_0aa0_0bb0_0000).to_f.should.eql?(23_058_441_774_644_068_352.0)
+      bignum_value(0x8000_0000_0000_0ccc).to_f.should.eql?(27_670_116_110_564_330_700.0)
+      (-bignum_value(99)).to_f.should.eql?(-18_446_744_073_709_551_715.0)
     end
 
     it "converts number close to Float::MAX without exceeding MAX or producing NaN" do
diff --git a/spec/ruby/core/integer/to_r_spec.rb b/spec/ruby/core/integer/to_r_spec.rb
index 4a40575b7f..2649c7c78d 100644
--- a/spec/ruby/core/integer/to_r_spec.rb
+++ b/spec/ruby/core/integer/to_r_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Integer#to_r" do
   it "returns a Rational object" do
-    309.to_r.should be_an_instance_of(Rational)
+    309.to_r.should.instance_of?(Rational)
   end
 
   it "constructs a rational number with self as the numerator" do
@@ -15,12 +15,12 @@ describe "Integer#to_r" do
 
   it "works even if self is a Bignum" do
     bignum = 99999**999
-    bignum.should be_an_instance_of(Bignum)
+    bignum.should.instance_of?(Integer)
     bignum.to_r.should == Rational(bignum, 1)
   end
 
   it "raises an ArgumentError if given any arguments" do
-    -> { 287.to_r(2) }.should raise_error(ArgumentError)
-    -> { 9102826.to_r(309, [], 71) }.should raise_error(ArgumentError)
+    -> { 287.to_r(2) }.should.raise(ArgumentError)
+    -> { 9102826.to_r(309, [], 71) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/integer/to_s_spec.rb b/spec/ruby/core/integer/to_s_spec.rb
index 7988bfde7a..4970a2a12f 100644
--- a/spec/ruby/core/integer/to_s_spec.rb
+++ b/spec/ruby/core/integer/to_s_spec.rb
@@ -13,10 +13,10 @@ describe "Integer#to_s" do
       end
 
       it "raises an ArgumentError if the base is less than 2 or higher than 36" do
-        -> { 123.to_s(-1) }.should raise_error(ArgumentError)
-        -> { 123.to_s(0)  }.should raise_error(ArgumentError)
-        -> { 123.to_s(1)  }.should raise_error(ArgumentError)
-        -> { 123.to_s(37) }.should raise_error(ArgumentError)
+        -> { 123.to_s(-1) }.should.raise(ArgumentError)
+        -> { 123.to_s(0)  }.should.raise(ArgumentError)
+        -> { 123.to_s(1)  }.should.raise(ArgumentError)
+        -> { 123.to_s(37) }.should.raise(ArgumentError)
       end
     end
 
@@ -39,12 +39,12 @@ describe "Integer#to_s" do
 
     it "returns a String in US-ASCII encoding when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      1.to_s.encoding.should equal(Encoding::US_ASCII)
+      1.to_s.encoding.should.equal?(Encoding::US_ASCII)
     end
 
     it "returns a String in US-ASCII encoding when Encoding.default_internal is not nil" do
       Encoding.default_internal = Encoding::IBM437
-      1.to_s.encoding.should equal(Encoding::US_ASCII)
+      1.to_s.encoding.should.equal?(Encoding::US_ASCII)
     end
   end
 
@@ -59,18 +59,18 @@ describe "Integer#to_s" do
       end
 
       it "raises an ArgumentError if the base is less than 2 or higher than 36" do
-        -> { 123.to_s(-1) }.should raise_error(ArgumentError)
-        -> { 123.to_s(0) }.should raise_error(ArgumentError)
-        -> { 123.to_s(1) }.should raise_error(ArgumentError)
-        -> { 123.to_s(37) }.should raise_error(ArgumentError)
+        -> { 123.to_s(-1) }.should.raise(ArgumentError)
+        -> { 123.to_s(0) }.should.raise(ArgumentError)
+        -> { 123.to_s(1) }.should.raise(ArgumentError)
+        -> { 123.to_s(37) }.should.raise(ArgumentError)
       end
     end
 
     describe "when given no base" do
       it "returns self converted to a String using base 10" do
-        bignum_value(9).to_s.should == "9223372036854775817"
-        bignum_value.to_s.should == "9223372036854775808"
-        (-bignum_value(675)).to_s.should == "-9223372036854776483"
+        bignum_value(9).to_s.should == "18446744073709551625"
+        bignum_value.to_s.should == "18446744073709551616"
+        (-bignum_value(675)).to_s.should == "-18446744073709552291"
       end
     end
 
@@ -84,12 +84,12 @@ describe "Integer#to_s" do
 
     it "returns a String in US-ASCII encoding when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      bignum_value.to_s.encoding.should equal(Encoding::US_ASCII)
+      bignum_value.to_s.encoding.should.equal?(Encoding::US_ASCII)
     end
 
     it "returns a String in US-ASCII encoding when Encoding.default_internal is not nil" do
       Encoding.default_internal = Encoding::IBM437
-      bignum_value.to_s.encoding.should equal(Encoding::US_ASCII)
+      bignum_value.to_s.encoding.should.equal?(Encoding::US_ASCII)
     end
   end
 end
diff --git a/spec/ruby/core/integer/truncate_spec.rb b/spec/ruby/core/integer/truncate_spec.rb
index db16e74be4..b95c183cf3 100644
--- a/spec/ruby/core/integer/truncate_spec.rb
+++ b/spec/ruby/core/integer/truncate_spec.rb
@@ -8,12 +8,12 @@ describe "Integer#truncate" do
 
   context "precision argument specified as part of the truncate method is negative" do
     it "returns an integer with at least precision.abs trailing zeros" do
-      1832.truncate(-1).should eql(1830)
-      1832.truncate(-2).should eql(1800)
-      1832.truncate(-3).should eql(1000)
-      -1832.truncate(-1).should eql(-1830)
-      -1832.truncate(-2).should eql(-1800)
-      -1832.truncate(-3).should eql(-1000)
+      1832.truncate(-1).should.eql?(1830)
+      1832.truncate(-2).should.eql?(1800)
+      1832.truncate(-3).should.eql?(1000)
+      -1832.truncate(-1).should.eql?(-1830)
+      -1832.truncate(-2).should.eql?(-1800)
+      -1832.truncate(-3).should.eql?(-1000)
     end
   end
 end
diff --git a/spec/ruby/core/integer/try_convert_spec.rb b/spec/ruby/core/integer/try_convert_spec.rb
new file mode 100644
index 0000000000..8c9b4276b9
--- /dev/null
+++ b/spec/ruby/core/integer/try_convert_spec.rb
@@ -0,0 +1,48 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Integer.try_convert" do
+  it "returns the argument if it's an Integer" do
+    x = 42
+    Integer.try_convert(x).should.equal?(x)
+  end
+
+  it "returns nil when the argument does not respond to #to_int" do
+    Integer.try_convert(Object.new).should == nil
+  end
+
+  it "sends #to_int to the argument and returns the result if it's nil" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(nil)
+    Integer.try_convert(obj).should == nil
+  end
+
+  it "sends #to_int to the argument and returns the result if it's an Integer" do
+    x = 234
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(x)
+    Integer.try_convert(obj).should.equal?(x)
+  end
+
+  it "sends #to_int to the argument and raises TypeError if it's not a kind of Integer" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(Object.new)
+    -> {
+      Integer.try_convert obj
+    }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_int gives Object)")
+  end
+
+  it "responds with a different error message when it raises a TypeError, depending on the type of the non-Integer object :to_int returns" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return("A String")
+    -> {
+      Integer.try_convert obj
+    }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_int gives String)")
+  end
+
+  it "does not rescue exceptions raised by #to_int" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_raise(RuntimeError)
+    -> { Integer.try_convert obj }.should.raise(RuntimeError)
+  end
+end
diff --git a/spec/ruby/core/integer/uminus_spec.rb b/spec/ruby/core/integer/uminus_spec.rb
index b6b110dec4..7a9cfe89bf 100644
--- a/spec/ruby/core/integer/uminus_spec.rb
+++ b/spec/ruby/core/integer/uminus_spec.rb
@@ -20,11 +20,11 @@ describe "Integer#-@" do
 
   context "bignum" do
     it "returns self as a negative value" do
-      bignum_value.send(:-@).should == -9223372036854775808
-      (-bignum_value).send(:-@).should == 9223372036854775808
+      bignum_value.send(:-@).should == -18446744073709551616
+      (-bignum_value).send(:-@).should == 18446744073709551616
 
-      bignum_value(921).send(:-@).should == -9223372036854776729
-      (-bignum_value(921).send(:-@)).should == 9223372036854776729
+      bignum_value(921).send(:-@).should == -18446744073709552537
+      (-bignum_value(921).send(:-@)).should == 18446744073709552537
     end
   end
 end
diff --git a/spec/ruby/core/integer/upto_spec.rb b/spec/ruby/core/integer/upto_spec.rb
index 6049eb173e..ba63dcc9ea 100644
--- a/spec/ruby/core/integer/upto_spec.rb
+++ b/spec/ruby/core/integer/upto_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
 
-describe "Integer#upto [stop] when self and stop are Fixnums" do
+describe "Integer#upto [stop] when self and stop are Integers" do
   it "does not yield when stop is less than self" do
     result = []
     5.upto(4) { |x| result << x }
@@ -27,8 +27,8 @@ describe "Integer#upto [stop] when self and stop are Fixnums" do
   end
 
   it "raises an ArgumentError for non-numeric endpoints" do
-    -> { 1.upto("A") {|x| p x} }.should raise_error(ArgumentError)
-    -> { 1.upto(nil) {|x| p x} }.should raise_error(ArgumentError)
+    -> { 1.upto("A") {|x| p x} }.should.raise(ArgumentError)
+    -> { 1.upto(nil) {|x| p x} }.should.raise(ArgumentError)
   end
 
   describe "when no block is given" do
@@ -45,9 +45,9 @@ describe "Integer#upto [stop] when self and stop are Fixnums" do
       describe "size" do
         it "raises an ArgumentError for non-numeric endpoints" do
           enum = 1.upto("A")
-          -> { enum.size }.should raise_error(ArgumentError)
+          -> { enum.size }.should.raise(ArgumentError)
           enum = 1.upto(nil)
-          -> { enum.size }.should raise_error(ArgumentError)
+          -> { enum.size }.should.raise(ArgumentError)
         end
 
         it "returns stop - self + 1" do
diff --git a/spec/ruby/core/integer/zero_spec.rb b/spec/ruby/core/integer/zero_spec.rb
new file mode 100644
index 0000000000..bd362c4181
--- /dev/null
+++ b/spec/ruby/core/integer/zero_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "Integer#zero?" do
+  it "returns true if self is 0" do
+    0.should.zero?
+    1.should_not.zero?
+    -1.should_not.zero?
+  end
+
+  it "Integer#zero? overrides Numeric#zero?" do
+    42.method(:zero?).owner.should == Integer
+  end
+end
diff --git a/spec/ruby/core/io/advise_spec.rb b/spec/ruby/core/io/advise_spec.rb
index 0a845487e2..b77ed53ad4 100644
--- a/spec/ruby/core/io/advise_spec.rb
+++ b/spec/ruby/core/io/advise_spec.rb
@@ -14,83 +14,73 @@ describe "IO#advise" do
   it "raises a TypeError if advise is not a Symbol" do
     -> {
       @io.advise("normal")
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError if offset cannot be coerced to an Integer" do
     -> {
       @io.advise(:normal, "wat")
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError if len cannot be coerced to an Integer" do
     -> {
       @io.advise(:normal, 0, "wat")
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a RangeError if offset is too big" do
     -> {
       @io.advise(:normal, 10 ** 32)
-    }.should raise_error(RangeError)
+    }.should.raise(RangeError)
   end
 
   it "raises a RangeError if len is too big" do
     -> {
       @io.advise(:normal, 0, 10 ** 32)
-    }.should raise_error(RangeError)
+    }.should.raise(RangeError)
   end
 
   it "raises a NotImplementedError if advise is not recognized" do
     ->{
       @io.advise(:foo)
-    }.should raise_error(NotImplementedError)
+    }.should.raise(NotImplementedError)
   end
 
   it "supports the normal advice type" do
-    @io.advise(:normal).should be_nil
+    @io.advise(:normal).should == nil
   end
 
   it "supports the sequential advice type" do
-    @io.advise(:sequential).should be_nil
+    @io.advise(:sequential).should == nil
   end
 
   it "supports the random advice type" do
-    @io.advise(:random).should be_nil
+    @io.advise(:random).should == nil
   end
 
   it "supports the dontneed advice type" do
-    @io.advise(:dontneed).should be_nil
+    @io.advise(:dontneed).should == nil
   end
 
   it "supports the noreuse advice type" do
-    @io.advise(:noreuse).should be_nil
+    @io.advise(:noreuse).should == nil
   end
 
   platform_is_not :linux do
     it "supports the willneed advice type" do
-      @io.advise(:willneed).should be_nil
+      @io.advise(:willneed).should == nil
     end
   end
 
-  platform_is :linux do
+  guard -> { platform_is :linux and kernel_version_is '3.6' } do # [ruby-core:65355] tmpfs is not supported
     it "supports the willneed advice type" do
-      require 'etc'
-      uname = if Etc.respond_to?(:uname)
-                Etc.uname[:release]
-              else
-                `uname -r`.chomp
-              end
-      if (uname.split('.').map(&:to_i) <=> [3,6]) < 0
-        skip "[ruby-core:65355] tmpfs is not supported"
-      else
-        @io.advise(:willneed).should be_nil
-      end
+      @io.advise(:willneed).should == nil
     end
   end
 
   it "raises an IOError if the stream is closed" do
     @io.close
-    -> { @io.advise(:normal) }.should raise_error(IOError)
+    -> { @io.advise(:normal) }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/autoclose_spec.rb b/spec/ruby/core/io/autoclose_spec.rb
new file mode 100644
index 0000000000..596f3d6934
--- /dev/null
+++ b/spec/ruby/core/io/autoclose_spec.rb
@@ -0,0 +1,77 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "IO#autoclose?" do
+  before :each do
+    @io = IOSpecs.io_fixture "lines.txt"
+  end
+
+  after :each do
+    @io.autoclose = true unless @io.closed?
+    @io.close unless @io.closed?
+  end
+
+  it "is set to true by default" do
+    @io.should.autoclose?
+  end
+
+  it "cannot be queried on a closed IO object" do
+    @io.close
+    -> { @io.autoclose? }.should.raise(IOError, /closed stream/)
+  end
+end
+
+describe "IO#autoclose=" do
+  before :each do
+    @io = IOSpecs.io_fixture "lines.txt"
+  end
+
+  after :each do
+    @io.autoclose = true unless @io.closed?
+    @io.close unless @io.closed?
+  end
+
+  it "can be set to true" do
+    @io.autoclose = false
+    @io.autoclose = true
+    @io.should.autoclose?
+  end
+
+  it "can be set to false" do
+    @io.autoclose = true
+    @io.autoclose = false
+    @io.should_not.autoclose?
+  end
+
+  it "can be set to any truthy value" do
+    @io.autoclose = false
+    @io.autoclose = 42
+    @io.should.autoclose?
+
+    @io.autoclose = false
+    @io.autoclose = Object.new
+    @io.should.autoclose?
+  end
+
+  it "can be set to any falsy value" do
+    @io.autoclose = true
+    @io.autoclose = nil
+    @io.should_not.autoclose?
+  end
+
+  it "can be set multiple times" do
+    @io.autoclose = true
+    @io.should.autoclose?
+
+    @io.autoclose = false
+    @io.should_not.autoclose?
+
+    @io.autoclose = true
+    @io.should.autoclose?
+  end
+
+  it "cannot be set on a closed IO object" do
+    @io.close
+    -> { @io.autoclose = false }.should.raise(IOError, /closed stream/)
+  end
+end
diff --git a/spec/ruby/core/io/binmode_spec.rb b/spec/ruby/core/io/binmode_spec.rb
index b698777cad..8117229c91 100644
--- a/spec/ruby/core/io/binmode_spec.rb
+++ b/spec/ruby/core/io/binmode_spec.rb
@@ -13,11 +13,11 @@ describe "IO#binmode" do
 
   it "returns self" do
     @io = new_io(@name)
-    @io.binmode.should equal(@io)
+    @io.binmode.should.equal?(@io)
   end
 
   it "raises an IOError on closed stream" do
-    -> { IOSpecs.closed_io.binmode }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.binmode }.should.raise(IOError)
   end
 
   it "sets external encoding to binary" do
@@ -47,9 +47,9 @@ describe "IO#binmode?" do
   end
 
   it "is true after a call to IO#binmode" do
-    @file.binmode?.should be_false
+    @file.binmode?.should == false
     @file.binmode
-    @file.binmode?.should be_true
+    @file.binmode?.should == true
   end
 
   it "propagates to dup'ed IO objects" do
@@ -57,4 +57,8 @@ describe "IO#binmode?" do
     @duped = @file.dup
     @duped.binmode?.should == @file.binmode?
   end
+
+  it "raises an IOError on closed stream" do
+    -> { IOSpecs.closed_io.binmode? }.should.raise(IOError)
+  end
 end
diff --git a/spec/ruby/core/io/binread_spec.rb b/spec/ruby/core/io/binread_spec.rb
index a3f752d8f9..3023c7f177 100644
--- a/spec/ruby/core/io/binread_spec.rb
+++ b/spec/ruby/core/io/binread_spec.rb
@@ -38,10 +38,20 @@ describe "IO.binread" do
   end
 
   it "raises an ArgumentError when not passed a valid length" do
-    -> { IO.binread @fname, -1 }.should raise_error(ArgumentError)
+    -> { IO.binread @fname, -1 }.should.raise(ArgumentError)
   end
 
   it "raises an Errno::EINVAL when not passed a valid offset" do
-    -> { IO.binread @fname, 0, -1  }.should raise_error(Errno::EINVAL)
+    -> { IO.binread @fname, 0, -1  }.should.raise(Errno::EINVAL)
+  end
+
+  ruby_version_is ""..."4.0" do
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation given a path with a pipe" do
+      cmd = "|echo ok"
+      -> {
+        IO.binread(cmd)
+      }.should complain(/IO process creation with a leading '\|'/)
+    end
   end
 end
diff --git a/spec/ruby/core/io/buffer/and_spec.rb b/spec/ruby/core/io/buffer/and_spec.rb
new file mode 100644
index 0000000000..3cea163b0e
--- /dev/null
+++ b/spec/ruby/core/io/buffer/and_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+
+describe :io_buffer_and, shared: true do
+  it "applies the argument buffer as an AND bit mask across the whole buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\x30\x02\x30\x04\x30".b
+        result.free
+      end
+    end
+  end
+
+  it "ignores extra parts of mask if it is longer than source buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F\x00\x00\x00\xFF\xFF") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\x30\x02\x00\x00\x00".b
+        result.free
+      end
+    end
+  end
+
+  it "raises TypeError if mask is not an IO::Buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      -> { buffer.send(@method, "\xF8\x8F") }.should.raise(TypeError, "wrong argument type String (expected IO::Buffer)")
+      -> { buffer.send(@method, 0xF8) }.should.raise(TypeError, "wrong argument type Integer (expected IO::Buffer)")
+      -> { buffer.send(@method, nil) }.should.raise(TypeError, "wrong argument type nil (expected IO::Buffer)")
+    end
+  end
+end
+
+describe "IO::Buffer#&" do
+  it_behaves_like :io_buffer_and, :&
+
+  it "creates a new internal buffer of the same size" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer & mask
+        result.should_not.equal? buffer
+        result.should.internal?
+        result.size.should == buffer.size
+        result.free
+        buffer.get_string.should == "12345".b
+      end
+    end
+  end
+end
+
+describe "IO::Buffer#and!" do
+  it_behaves_like :io_buffer_and, :and!
+
+  it "modifies the buffer in place" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.and!(mask)
+        result.should.equal? buffer
+        result.should.external?
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/bit_count_spec.rb b/spec/ruby/core/io/buffer/bit_count_spec.rb
new file mode 100644
index 0000000000..62f56f5b98
--- /dev/null
+++ b/spec/ruby/core/io/buffer/bit_count_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../../spec_helper'
+
+ruby_version_is "4.1" do
+  describe "IO::Buffer#bit_count" do
+    it "counts all set bits in the whole buffer" do
+      IO::Buffer.for(+"\xFF\x00\x0F") do |buffer|
+        buffer.bit_count.should == 12
+      end
+    end
+
+    it "returns 0 for a buffer of all zero bytes" do
+      IO::Buffer.for(+"\x00\x00\x00") do |buffer|
+        buffer.bit_count.should == 0
+      end
+    end
+
+    it "returns 8 * size for a buffer of all 0xFF bytes" do
+      IO::Buffer.for(+"\xFF" * 9) do |buffer|
+        buffer.bit_count.should == 72
+      end
+    end
+
+    it "returns 0 for an empty buffer" do
+      IO::Buffer.new(0).bit_count.should == 0
+    end
+
+    it "accepts an offset to start counting from (length defaults to remaining bytes)" do
+      IO::Buffer.for(+"\xFF\x00\x0F") do |buffer|
+        buffer.bit_count(0).should == 12  # offset=0 => entire buffer
+        buffer.bit_count(1).should == 4   # offset=1 => 0x00 + 0x0F
+        buffer.bit_count(2).should == 4   # offset=2 => 0x0F only
+      end
+    end
+
+    it "accepts an offset and length to restrict the counted region" do
+      IO::Buffer.for(+"\xFF\x00\x0F") do |buffer|
+        buffer.bit_count(0, 1).should == 8  # just 0xFF
+        buffer.bit_count(1, 1).should == 0  # just 0x00
+        buffer.bit_count(2, 1).should == 4  # just 0x0F
+        buffer.bit_count(1, 2).should == 4  # 0x00 + 0x0F
+      end
+    end
+
+    it "handles 8-byte aligned buffers efficiently" do
+      IO::Buffer.for(+"\xAA" * 8) do |buffer|
+        # 0xAA = 10101010 => 4 bits per byte => 32 total
+        buffer.bit_count.should == 32
+      end
+    end
+
+    it "raises ArgumentError when offset + length exceeds buffer size" do
+      IO::Buffer.for(+"\xFF") do |buffer|
+        -> { buffer.bit_count(0, 2) }.should.raise(ArgumentError)
+        -> { buffer.bit_count(1, 1) }.should.raise(ArgumentError)
+      end
+    end
+
+    it "returns an Integer" do
+      IO::Buffer.for(+"\xFF") do |buffer|
+        buffer.bit_count.should.is_a?(Integer)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/empty_spec.rb b/spec/ruby/core/io/buffer/empty_spec.rb
new file mode 100644
index 0000000000..4cceb4dc0d
--- /dev/null
+++ b/spec/ruby/core/io/buffer/empty_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/null_and_empty'
+
+describe "IO::Buffer#empty?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it_behaves_like :io_buffer_null_and_empty, :empty?
+
+  it "is true for a 0-length String-backed buffer created with .for" do
+    @buffer = IO::Buffer.for("")
+    @buffer.empty?.should == true
+  end
+
+  it "is true for a 0-length String-backed buffer created with .string" do
+    IO::Buffer.string(0) do |buffer|
+      buffer.empty?.should == true
+    end
+  end
+
+  it "is true for a 0-length slice of a buffer with size > 0" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.slice(3, 0).empty?.should == true
+  end
+end
diff --git a/spec/ruby/core/io/buffer/external_spec.rb b/spec/ruby/core/io/buffer/external_spec.rb
new file mode 100644
index 0000000000..18b2ee0d06
--- /dev/null
+++ b/spec/ruby/core/io/buffer/external_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#external?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer with externally-managed memory" do
+    @buffer = IO::Buffer.for("string")
+    @buffer.external?.should == true
+  end
+
+  it "is false for a buffer with self-managed memory" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::MAPPED)
+    @buffer.external?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.external?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/for_spec.rb b/spec/ruby/core/io/buffer/for_spec.rb
new file mode 100644
index 0000000000..4c614f74b0
--- /dev/null
+++ b/spec/ruby/core/io/buffer/for_spec.rb
@@ -0,0 +1,95 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer.for" do
+  before :each do
+    @string = +"för striñg"
+  end
+
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  context "without a block" do
+    it "copies string's contents, creating a separate read-only buffer" do
+      @buffer = IO::Buffer.for(@string)
+
+      @buffer.size.should == @string.bytesize
+      @buffer.get_string.should == @string.b
+
+      @string[0] = "d"
+      @buffer.get_string(0, 1).should == "f".b
+
+      -> { @buffer.set_string("d") }.should.raise(IO::Buffer::AccessError, "Buffer is not writable!")
+    end
+
+    it "creates an external, read-only buffer" do
+      @buffer = IO::Buffer.for(@string)
+
+      @buffer.should_not.internal?
+      @buffer.should_not.mapped?
+      @buffer.should.external?
+
+      @buffer.should_not.empty?
+      @buffer.should_not.null?
+
+      @buffer.should_not.shared?
+      @buffer.should_not.private?
+      @buffer.should.readonly?
+
+      @buffer.should_not.locked?
+      @buffer.should.valid?
+    end
+  end
+
+  context "with a block" do
+    it "returns the last value in the block" do
+      value =
+        IO::Buffer.for(@string) do |buffer|
+          buffer.size * 3
+        end
+      value.should == @string.bytesize * 3
+    end
+
+    it "frees the buffer at the end of the block" do
+      IO::Buffer.for(@string) do |buffer|
+        @buffer = buffer
+        @buffer.should_not.null?
+      end
+      @buffer.should.null?
+    end
+
+    context "if string is not frozen" do
+      it "creates a modifiable string-backed buffer" do
+        IO::Buffer.for(@string) do |buffer|
+          buffer.size.should == @string.bytesize
+          buffer.get_string.should == @string.b
+
+          buffer.should_not.readonly?
+          buffer.should_not.locked?
+
+          buffer.set_string("ghost shell")
+          @string.should == "ghost shellg"
+        end
+      end
+
+      it "locks the original string to prevent modification" do
+        IO::Buffer.for(@string) do |_buffer|
+          -> { @string[0] = "t" }.should.raise(RuntimeError, "can't modify string; temporarily locked")
+        end
+        @string[1] = "u"
+        @string.should == "fur striñg"
+      end
+    end
+
+    context "if string is frozen" do
+      it "creates a read-only string-backed buffer" do
+        IO::Buffer.for(@string.freeze) do |buffer|
+          buffer.should.readonly?
+
+          -> { buffer.set_string("ghost shell") }.should.raise(IO::Buffer::AccessError, "Buffer is not writable!")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/free_spec.rb b/spec/ruby/core/io/buffer/free_spec.rb
new file mode 100644
index 0000000000..20fb7b901f
--- /dev/null
+++ b/spec/ruby/core/io/buffer/free_spec.rb
@@ -0,0 +1,102 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#free" do
+  context "with a buffer created with .new" do
+    it "frees internal memory and nullifies the buffer" do
+      buffer = IO::Buffer.new(4)
+      buffer.free
+      buffer.null?.should == true
+    end
+
+    it "frees mapped memory and nullifies the buffer" do
+      buffer = IO::Buffer.new(4, IO::Buffer::MAPPED)
+      buffer.free
+      buffer.null?.should == true
+    end
+  end
+
+  context "with a file-backed buffer created with .map" do
+    it "frees mapped memory and nullifies the buffer" do
+      File.open(__FILE__, "r") do |file|
+        buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+        buffer.free
+        buffer.null?.should == true
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .for" do
+    context "without a block" do
+      it "disassociates the buffer from the string and nullifies the buffer" do
+        string = +"test"
+        buffer = IO::Buffer.for(string)
+        # Read-only buffer, can't modify the string.
+        buffer.free
+        buffer.null?.should == true
+      end
+    end
+
+    context "with a block" do
+      it "disassociates the buffer from the string and nullifies the buffer" do
+        string = +"test"
+        IO::Buffer.for(string) do |buffer|
+          buffer.set_string("meat")
+          buffer.free
+          buffer.null?.should == true
+        end
+        string.should == "meat"
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .string" do
+    it "disassociates the buffer from the string and nullifies the buffer" do
+      string =
+        IO::Buffer.string(4) do |buffer|
+          buffer.set_string("meat")
+          buffer.free
+          buffer.null?.should == true
+        end
+      string.should == "meat"
+    end
+  end
+
+  it "can be called repeatedly without an error" do
+    buffer = IO::Buffer.new(4)
+    buffer.free
+    buffer.null?.should == true
+    buffer.free
+    buffer.null?.should == true
+  end
+
+  it "is disallowed while locked, raising IO::Buffer::LockedError" do
+    buffer = IO::Buffer.new(4)
+    buffer.locked do
+      -> { buffer.free }.should.raise(IO::Buffer::LockedError, "Buffer is locked!")
+    end
+    buffer.free
+    buffer.null?.should == true
+  end
+
+  context "with a slice of a buffer" do
+    it "nullifies the slice, not touching the buffer" do
+      buffer = IO::Buffer.new(4)
+      slice = buffer.slice(0, 2)
+
+      slice.free
+      slice.null?.should == true
+      buffer.null?.should == false
+
+      buffer.free
+    end
+
+    it "nullifies buffer, invalidating the slice" do
+      buffer = IO::Buffer.new(4)
+      slice = buffer.slice(0, 2)
+
+      buffer.free
+      slice.null?.should == false
+      slice.valid?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/initialize_spec.rb b/spec/ruby/core/io/buffer/initialize_spec.rb
new file mode 100644
index 0000000000..dba6fddc79
--- /dev/null
+++ b/spec/ruby/core/io/buffer/initialize_spec.rb
@@ -0,0 +1,119 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#initialize" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "creates a new zero-filled buffer with default size" do
+    @buffer = IO::Buffer.new
+    @buffer.size.should == IO::Buffer::DEFAULT_SIZE
+    @buffer.each(:U8).should.all? { |_offset, value| value.eql?(0) }
+  end
+
+  it "creates a buffer with default state" do
+    @buffer = IO::Buffer.new
+
+    @buffer.should_not.external?
+
+    @buffer.should_not.shared?
+    @buffer.should_not.private?
+    @buffer.should_not.readonly?
+
+    @buffer.should_not.empty?
+    @buffer.should_not.null?
+
+    @buffer.should_not.locked?
+    @buffer.should.valid?
+  end
+
+  context "with size argument" do
+    it "creates a new internal buffer if size is less than IO::Buffer::PAGE_SIZE" do
+      size = IO::Buffer::PAGE_SIZE - 1
+      @buffer = IO::Buffer.new(size)
+      @buffer.size.should == size
+      @buffer.should_not.empty?
+
+      @buffer.should.internal?
+      @buffer.should_not.mapped?
+    end
+
+    it "creates a new mapped buffer if size is greater than or equal to IO::Buffer::PAGE_SIZE" do
+      size = IO::Buffer::PAGE_SIZE
+      @buffer = IO::Buffer.new(size)
+      @buffer.size.should == size
+      @buffer.should_not.empty?
+
+      @buffer.should_not.internal?
+      @buffer.should.mapped?
+    end
+
+    it "creates a null buffer if size is 0" do
+      @buffer = IO::Buffer.new(0)
+      @buffer.should.null?
+      @buffer.should.empty?
+    end
+
+    it "raises TypeError if size is not an Integer" do
+      -> { IO::Buffer.new(nil) }.should.raise(TypeError, "not an Integer")
+      -> { IO::Buffer.new(10.0) }.should.raise(TypeError, "not an Integer")
+    end
+
+    it "raises ArgumentError if size is negative" do
+      -> { IO::Buffer.new(-1) }.should.raise(ArgumentError, "Size can't be negative!")
+    end
+  end
+
+  context "with size and flags arguments" do
+    it "forces mapped buffer with IO::Buffer::MAPPED flag" do
+      @buffer = IO::Buffer.new(IO::Buffer::PAGE_SIZE - 1, IO::Buffer::MAPPED)
+      @buffer.should.mapped?
+      @buffer.should_not.internal?
+      @buffer.should_not.empty?
+    end
+
+    it "forces internal buffer with IO::Buffer::INTERNAL flag" do
+      @buffer = IO::Buffer.new(IO::Buffer::PAGE_SIZE, IO::Buffer::INTERNAL)
+      @buffer.should.internal?
+      @buffer.should_not.mapped?
+      @buffer.should_not.empty?
+    end
+
+    it "allows extra flags" do
+      @buffer = IO::Buffer.new(10, IO::Buffer::INTERNAL | IO::Buffer::SHARED | IO::Buffer::READONLY)
+      @buffer.should.internal?
+      @buffer.should.shared?
+      @buffer.should.readonly?
+    end
+
+    it "ignores flags if size is 0" do
+      @buffer = IO::Buffer.new(0, 0xffff)
+      @buffer.should.null?
+      @buffer.should.empty?
+
+      @buffer.should_not.internal?
+      @buffer.should_not.mapped?
+      @buffer.should_not.external?
+
+      @buffer.should_not.shared?
+      @buffer.should_not.readonly?
+
+      @buffer.should_not.locked?
+      @buffer.should.valid?
+    end
+
+    it "raises IO::Buffer::AllocationError if neither IO::Buffer::MAPPED nor IO::Buffer::INTERNAL is given" do
+      -> { IO::Buffer.new(10, IO::Buffer::READONLY) }.should.raise(IO::Buffer::AllocationError, "Could not allocate buffer!")
+      -> { IO::Buffer.new(10, 0) }.should.raise(IO::Buffer::AllocationError, "Could not allocate buffer!")
+    end
+
+    it "raises ArgumentError if flags is negative" do
+      -> { IO::Buffer.new(10, -1) }.should.raise(ArgumentError, "Flags can't be negative!")
+    end
+
+    it "raises TypeError with non-Integer flags" do
+      -> { IO::Buffer.new(10, 0.0) }.should.raise(TypeError, "not an Integer")
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/internal_spec.rb b/spec/ruby/core/io/buffer/internal_spec.rb
new file mode 100644
index 0000000000..73e19eb85e
--- /dev/null
+++ b/spec/ruby/core/io/buffer/internal_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#internal?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for an internally-allocated buffer" do
+    @buffer = IO::Buffer.new(12)
+    @buffer.internal?.should == true
+  end
+
+  it "is false for an externally-allocated buffer" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::MAPPED)
+    @buffer.internal?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.internal?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/locked_spec.rb b/spec/ruby/core/io/buffer/locked_spec.rb
new file mode 100644
index 0000000000..249026aa8a
--- /dev/null
+++ b/spec/ruby/core/io/buffer/locked_spec.rb
@@ -0,0 +1,75 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#locked" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  context "when buffer is locked" do
+    it "allows reading and writing operations on the buffer" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.set_string("test")
+      @buffer.locked do
+        @buffer.get_string.should == "test"
+        @buffer.set_string("meat")
+      end
+      @buffer.get_string.should == "meat"
+    end
+
+    it "disallows operations changing buffer itself, raising IO::Buffer::LockedError" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.locked do
+        # Just an example, each method is responsible for checking the lock state.
+        -> { @buffer.resize(8) }.should.raise(IO::Buffer::LockedError)
+      end
+    end
+  end
+
+  it "disallows reentrant locking, raising IO::Buffer::LockedError" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      -> { @buffer.locked {} }.should.raise(IO::Buffer::LockedError, "Buffer already locked!")
+    end
+  end
+
+  it "does not propagate to buffer's slices" do
+    @buffer = IO::Buffer.new(4)
+    slice = @buffer.slice(0, 2)
+    @buffer.locked do
+      @buffer.locked?.should == true
+      slice.locked?.should == false
+      slice.locked { slice.locked?.should == true }
+    end
+  end
+
+  it "does not propagate backwards from buffer's slices" do
+    @buffer = IO::Buffer.new(4)
+    slice = @buffer.slice(0, 2)
+    slice.locked do
+      slice.locked?.should == true
+      @buffer.locked?.should == false
+      @buffer.locked { @buffer.locked?.should == true }
+    end
+  end
+end
+
+describe "IO::Buffer#locked?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is false by default" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked?.should == false
+  end
+
+  it "is true only inside of #locked block" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      @buffer.locked?.should == true
+    end
+    @buffer.locked?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/map_spec.rb b/spec/ruby/core/io/buffer/map_spec.rb
new file mode 100644
index 0000000000..97764c2dd7
--- /dev/null
+++ b/spec/ruby/core/io/buffer/map_spec.rb
@@ -0,0 +1,347 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer.map" do
+  before :all do
+    @tmp_files = []
+
+    @big_file_name = nil
+    @small_file_name = nil
+  end
+
+  after :all do
+    @tmp_files.each {|file| File.delete(file)}
+  end
+
+  def open_fixture
+    unless @small_file_name
+      @small_file_name = tmp("read_text.txt")
+      File.copy_stream(fixture(__dir__, "read_text.txt"), @small_file_name)
+      @tmp_files << @small_file_name
+    end
+    File.open(@small_file_name, "rb+")
+  end
+
+  def open_big_file_fixture
+    unless @big_file_name
+      @big_file_name = tmp("big_file")
+      # Usually 4 kibibytes + 16 bytes
+      File.write(@big_file_name, "12345678" * (IO::Buffer::PAGE_SIZE / 8 + 2))
+      @tmp_files << @big_file_name
+    end
+    File.open(@big_file_name, "rb+")
+  end
+
+  after :each do
+    @buffer&.free
+    @buffer = nil
+    @file&.close
+    @file = nil
+  end
+
+  it "creates a new buffer mapped from a file" do
+    @file = open_fixture
+    @buffer = IO::Buffer.map(@file)
+
+    @buffer.size.should == 9
+    @buffer.get_string.should == "abcâdef\n".b
+  end
+
+  it "allows to close the file after creating buffer, retaining mapping" do
+    file = open_fixture
+    @buffer = IO::Buffer.map(file)
+    file.close
+
+    @buffer.get_string.should == "abcâdef\n".b
+  end
+
+  it "creates a mapped, external, shared buffer" do
+    @file = open_fixture
+    @buffer = IO::Buffer.map(@file)
+
+    @buffer.should_not.internal?
+    @buffer.should.mapped?
+    @buffer.should.external?
+
+    @buffer.should_not.empty?
+    @buffer.should_not.null?
+
+    @buffer.should.shared?
+    @buffer.should_not.private?
+    @buffer.should_not.readonly?
+
+    @buffer.should_not.locked?
+    @buffer.should.valid?
+  end
+
+  # IO::Buffer.map seems not shareable across processes on OpenBSD.
+  # See https://rubyci.s3.amazonaws.com/openbsd-current/ruby-master/log/20260129T163005Z.fail.html.gz
+  platform_is_not :openbsd do
+    guard -> { Process.respond_to?(:fork) } do
+      it "is shareable across processes" do
+        file_name = tmp("shared_buffer")
+        @file = File.open(file_name, "w+")
+        @file << "I'm private"
+        @file.rewind
+        @buffer = IO::Buffer.map(@file)
+
+        IO.popen("-") do |child_pipe|
+          if child_pipe
+            # Synchronize on child's output.
+            child_pipe.readlines.first.chomp.should == @buffer.to_s
+            @buffer.get_string.should == "I'm shared!"
+
+            @file.read.should == "I'm shared!"
+          else
+            @buffer.set_string("I'm shared!")
+            puts @buffer
+          end
+        ensure
+          child_pipe&.close
+        end
+      ensure
+        File.unlink(file_name)
+      end
+    end
+  end
+
+  context "with an empty file" do
+    ruby_version_is "4.0" do
+      it "raises ArgumentError" do
+        file_name = tmp("empty.txt")
+        @file = File.open(file_name, "wb+")
+        @tmp_files << file_name
+        -> { IO::Buffer.map(@file) }.should.raise(ArgumentError, "Invalid negative or zero file size!")
+      end
+    end
+  end
+
+  context "with a file opened only for reading" do
+    it "raises a SystemCallError unless read-only" do
+      @file = File.open(fixture(__dir__, "read_text.txt"), "rb")
+      -> { IO::Buffer.map(@file) }.should.raise(SystemCallError)
+    end
+  end
+
+  context "with size argument" do
+    it "limits the buffer to the specified size in bytes, starting from the start of the file" do
+      @file = open_fixture
+      @buffer = IO::Buffer.map(@file, 4)
+
+      @buffer.size.should == 4
+      @buffer.get_string.should == "abc\xC3".b
+    end
+
+    it "maps the whole file if size is nil" do
+      @file = open_fixture
+      @buffer = IO::Buffer.map(@file, nil)
+
+      @buffer.size.should == 9
+    end
+
+    context "if size is 0" do
+      ruby_version_is "4.0" do
+        it "raises ArgumentError" do
+          @file = open_fixture
+          -> { IO::Buffer.map(@file, 0) }.should.raise(ArgumentError, "Size can't be zero!")
+        end
+      end
+    end
+
+    it "raises TypeError if size is not an Integer or nil" do
+      @file = open_fixture
+      -> { IO::Buffer.map(@file, "10") }.should.raise(TypeError, "not an Integer")
+      -> { IO::Buffer.map(@file, 10.0) }.should.raise(TypeError, "not an Integer")
+    end
+
+    it "raises ArgumentError if size is negative" do
+      @file = open_fixture
+      -> { IO::Buffer.map(@file, -1) }.should.raise(ArgumentError, "Size can't be negative!")
+    end
+
+    ruby_version_is ""..."4.0" do
+      # May or may not cause a crash on access.
+      it "is undefined behavior if size is larger than file size"
+    end
+
+    ruby_version_is "4.0" do
+      it "raises ArgumentError if size is larger than file size" do
+        @file = open_fixture
+        -> { IO::Buffer.map(@file, 8192) }.should.raise(ArgumentError, "Size can't be larger than file size!")
+      end
+    end
+  end
+
+  context "with size and offset arguments" do
+    # Neither Windows nor macOS have clear, stable behavior with non-zero offset.
+    # https://bugs.ruby-lang.org/issues/21700
+    platform_is :linux do
+      context "if offset is an allowed value for system call" do
+        it "maps the span specified by size starting from the offset" do
+          @file = open_big_file_fixture
+          @buffer = IO::Buffer.map(@file, 14, IO::Buffer::PAGE_SIZE)
+
+          @buffer.size.should == 14
+          @buffer.get_string(0, 14).should == "12345678123456"
+        end
+
+        context "if size is nil" do
+          ruby_version_is ""..."4.0" do
+            it "maps the rest of the file" do
+              @file = open_big_file_fixture
+              @buffer = IO::Buffer.map(@file, nil, IO::Buffer::PAGE_SIZE)
+
+              @buffer.get_string(0, 1).should == "1"
+            end
+
+            it "incorrectly sets buffer's size to file's full size" do
+              @file = open_big_file_fixture
+              @buffer = IO::Buffer.map(@file, nil, IO::Buffer::PAGE_SIZE)
+
+              @buffer.size.should == @file.size
+            end
+          end
+
+          ruby_version_is "4.0" do
+            it "maps the rest of the file" do
+              @file = open_big_file_fixture
+              @buffer = IO::Buffer.map(@file, nil, IO::Buffer::PAGE_SIZE)
+
+              @buffer.get_string(0, 1).should == "1"
+            end
+
+            it "sets buffer's size to file's remaining size" do
+              @file = open_big_file_fixture
+              @buffer = IO::Buffer.map(@file, nil, IO::Buffer::PAGE_SIZE)
+
+              @buffer.size.should == (@file.size - IO::Buffer::PAGE_SIZE)
+            end
+          end
+        end
+      end
+    end
+
+    it "maps the file from the start if offset is 0" do
+      @file = open_fixture
+      @buffer = IO::Buffer.map(@file, 4, 0)
+
+      @buffer.size.should == 4
+      @buffer.get_string.should == "abc\xC3".b
+    end
+
+    ruby_version_is ""..."4.0" do
+      # May or may not cause a crash on access.
+      it "is undefined behavior if offset+size is larger than file size"
+    end
+
+    ruby_version_is "4.0" do
+      it "raises ArgumentError if offset+size is larger than file size" do
+        @file = open_big_file_fixture
+        -> { IO::Buffer.map(@file, 17, IO::Buffer::PAGE_SIZE) }.should.raise(ArgumentError, "Offset too large!")
+      ensure
+        # Windows requires the file to be closed before deletion.
+        @file.close unless @file.closed?
+      end
+    end
+
+    it "raises TypeError if offset is not convertible to Integer" do
+      @file = open_fixture
+      -> { IO::Buffer.map(@file, 4, "4096") }.should.raise(TypeError, /no implicit conversion/)
+      -> { IO::Buffer.map(@file, 4, nil) }.should.raise(TypeError, /no implicit conversion/)
+    end
+
+    ruby_version_is "4.0" do
+      it "raises ArgumentError if offset is negative" do
+        @file = open_fixture
+        -> { IO::Buffer.map(@file, 4, -1) }.should.raise(ArgumentError, "Offset can't be negative!")
+      end
+    end
+  end
+
+  context "with flags argument" do
+    context "when READONLY flag is specified" do
+      it "sets readonly flag on the buffer, allowing only reads" do
+        @file = open_fixture
+        @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::READONLY)
+
+        @buffer.should.readonly?
+
+        @buffer.get_string.should == "abc\xC3\xA2def\n".b
+      end
+
+      it "allows mapping read-only files" do
+        @file = File.open(fixture(__dir__, "read_text.txt"), "rb")
+        @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::READONLY)
+
+        @buffer.should.readonly?
+
+        @buffer.get_string.should == "abc\xC3\xA2def\n".b
+      end
+
+      it "causes IO::Buffer::AccessError on write" do
+        @file = open_fixture
+        @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::READONLY)
+
+        -> { @buffer.set_string("test") }.should.raise(IO::Buffer::AccessError, "Buffer is not writable!")
+      end
+    end
+
+    context "when PRIVATE is specified" do
+      it "sets private flag on the buffer, making it freely modifiable" do
+        @file = open_fixture
+        @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::PRIVATE)
+
+        @buffer.should.private?
+        @buffer.should_not.shared?
+        @buffer.should_not.external?
+
+        @buffer.get_string.should == "abc\xC3\xA2def\n".b
+        @buffer.set_string("test12345")
+        @buffer.get_string.should == "test12345".b
+
+        @file.read.should == "abcâdef\n".b
+      end
+
+      it "allows mapping read-only files and modifying the buffer" do
+        @file = File.open(fixture(__dir__, "read_text.txt"), "rb")
+        @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::PRIVATE)
+
+        @buffer.should.private?
+        @buffer.should_not.shared?
+        @buffer.should_not.external?
+
+        @buffer.get_string.should == "abc\xC3\xA2def\n".b
+        @buffer.set_string("test12345")
+        @buffer.get_string.should == "test12345".b
+
+        @file.read.should == "abcâdef\n".b
+      end
+
+      guard -> { Process.respond_to?(:fork) } do
+        it "is not shared across processes" do
+          file_name = tmp("shared_buffer")
+          @file = File.open(file_name, "w+")
+          @file << "I'm private"
+          @file.rewind
+          @buffer = IO::Buffer.map(@file, nil, 0, IO::Buffer::PRIVATE)
+
+          IO.popen("-") do |child_pipe|
+            if child_pipe
+              # Synchronize on child's output.
+              child_pipe.readlines.first.chomp.should == @buffer.to_s
+              @buffer.get_string.should == "I'm private"
+
+              @file.read.should == "I'm private"
+            else
+              @buffer.set_string("I'm shared!")
+              puts @buffer
+            end
+          ensure
+            child_pipe&.close
+          end
+        ensure
+          File.unlink(file_name)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/mapped_spec.rb b/spec/ruby/core/io/buffer/mapped_spec.rb
new file mode 100644
index 0000000000..0decb97704
--- /dev/null
+++ b/spec/ruby/core/io/buffer/mapped_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#mapped?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer with mapped memory" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::MAPPED)
+    @buffer.mapped?.should == true
+  end
+
+  it "is false for a buffer with non-mapped memory" do
+    @buffer = IO::Buffer.for("string")
+    @buffer.mapped?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.mapped?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/not_spec.rb b/spec/ruby/core/io/buffer/not_spec.rb
new file mode 100644
index 0000000000..4737a30bde
--- /dev/null
+++ b/spec/ruby/core/io/buffer/not_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../../spec_helper'
+
+describe :io_buffer_not, shared: true do
+  it "inverts every bit of the buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      result = buffer.send(@method)
+      result.get_string.should == "\xCE\xCD\xCC\xCB\xCA".b
+      result.free
+    end
+  end
+end
+
+describe "IO::Buffer#~" do
+  it_behaves_like :io_buffer_not, :~
+
+  it "creates a new internal buffer of the same size" do
+    IO::Buffer.for(+"12345") do |buffer|
+      result = ~buffer
+      result.should_not.equal? buffer
+      result.should.internal?
+      result.size.should == buffer.size
+      result.free
+    end
+  end
+end
+
+describe "IO::Buffer#not!" do
+  it_behaves_like :io_buffer_not, :not!
+
+  it "modifies the buffer in place" do
+    IO::Buffer.for(+"12345") do |buffer|
+      result = buffer.not!
+      result.should.equal? buffer
+      result.should.external?
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/null_spec.rb b/spec/ruby/core/io/buffer/null_spec.rb
new file mode 100644
index 0000000000..380a98bde1
--- /dev/null
+++ b/spec/ruby/core/io/buffer/null_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/null_and_empty'
+
+describe "IO::Buffer#null?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it_behaves_like :io_buffer_null_and_empty, :null?
+
+  it "is false for a 0-length String-backed buffer created with .for" do
+    @buffer = IO::Buffer.for("")
+    @buffer.null?.should == false
+  end
+
+  it "is false for a 0-length String-backed buffer created with .string" do
+    IO::Buffer.string(0) do |buffer|
+      buffer.null?.should == false
+    end
+  end
+
+  it "is false for a 0-length slice of a buffer with size > 0" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.slice(3, 0).null?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/or_spec.rb b/spec/ruby/core/io/buffer/or_spec.rb
new file mode 100644
index 0000000000..3e627c216c
--- /dev/null
+++ b/spec/ruby/core/io/buffer/or_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+
+describe :io_buffer_or, shared: true do
+  it "applies the argument buffer as an OR bit mask across the whole buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\xF9\xBF\xFB\xBF\xFD".b
+        result.free
+      end
+    end
+  end
+
+  it "ignores extra parts of mask if it is longer than source buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F\x00\x00\x00\xFF\xFF") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\xF9\xBF345".b
+        result.free
+      end
+    end
+  end
+
+  it "raises TypeError if mask is not an IO::Buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      -> { buffer.send(@method, "\xF8\x8F") }.should.raise(TypeError, "wrong argument type String (expected IO::Buffer)")
+      -> { buffer.send(@method, 0xF8) }.should.raise(TypeError, "wrong argument type Integer (expected IO::Buffer)")
+      -> { buffer.send(@method, nil) }.should.raise(TypeError, "wrong argument type nil (expected IO::Buffer)")
+    end
+  end
+end
+
+describe "IO::Buffer#|" do
+  it_behaves_like :io_buffer_or, :|
+
+  it "creates a new internal buffer of the same size" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer | mask
+        result.should_not.equal? buffer
+        result.should.internal?
+        result.size.should == buffer.size
+        result.free
+        buffer.get_string.should == "12345".b
+      end
+    end
+  end
+end
+
+describe "IO::Buffer#or!" do
+  it_behaves_like :io_buffer_or, :or!
+
+  it "modifies the buffer in place" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.or!(mask)
+        result.should.equal? buffer
+        result.should.external?
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/private_spec.rb b/spec/ruby/core/io/buffer/private_spec.rb
new file mode 100644
index 0000000000..6e6afee34c
--- /dev/null
+++ b/spec/ruby/core/io/buffer/private_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#private?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer created with PRIVATE flag" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::INTERNAL | IO::Buffer::PRIVATE)
+    @buffer.private?.should == true
+  end
+
+  it "is false for a buffer created without PRIVATE flag" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::INTERNAL)
+    @buffer.private?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.private?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/readonly_spec.rb b/spec/ruby/core/io/buffer/readonly_spec.rb
new file mode 100644
index 0000000000..4eefc9f29f
--- /dev/null
+++ b/spec/ruby/core/io/buffer/readonly_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#readonly?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer created with READONLY flag" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::INTERNAL | IO::Buffer::READONLY)
+    @buffer.readonly?.should == true
+  end
+
+  it "is true for a buffer that is non-writable" do
+    @buffer = IO::Buffer.for("string")
+    @buffer.readonly?.should == true
+  end
+
+  it "is false for a modifiable buffer" do
+    @buffer = IO::Buffer.new(12)
+    @buffer.readonly?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.readonly?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/resize_spec.rb b/spec/ruby/core/io/buffer/resize_spec.rb
new file mode 100644
index 0000000000..6e684475f3
--- /dev/null
+++ b/spec/ruby/core/io/buffer/resize_spec.rb
@@ -0,0 +1,151 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#resize" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  context "with a buffer created with .new" do
+    it "resizes internal buffer, preserving type" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.resize(IO::Buffer::PAGE_SIZE)
+      @buffer.size.should == IO::Buffer::PAGE_SIZE
+      @buffer.internal?.should == true
+      @buffer.mapped?.should == false
+    end
+
+    platform_is :linux do
+      it "resizes mapped buffer, preserving type" do
+        @buffer = IO::Buffer.new(IO::Buffer::PAGE_SIZE, IO::Buffer::MAPPED)
+        @buffer.resize(4)
+        @buffer.size.should == 4
+        @buffer.internal?.should == false
+        @buffer.mapped?.should == true
+      end
+    end
+
+    platform_is_not :linux do
+      it "resizes mapped buffer, changing type to internal" do
+        @buffer = IO::Buffer.new(IO::Buffer::PAGE_SIZE, IO::Buffer::MAPPED)
+        @buffer.resize(4)
+        @buffer.size.should == 4
+        @buffer.internal?.should == true
+        @buffer.mapped?.should == false
+      end
+    end
+  end
+
+  context "with a file-backed buffer created with .map" do
+    it "disallows resizing shared buffer, raising IO::Buffer::AccessError" do
+      File.open(__FILE__, "r+") do |file|
+        @buffer = IO::Buffer.map(file)
+        -> { @buffer.resize(10) }.should.raise(IO::Buffer::AccessError, "Cannot resize external buffer!")
+      end
+    end
+
+    it "resizes private buffer, discarding excess contents" do
+      File.open(__FILE__, "r") do |file|
+        @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::PRIVATE)
+        @buffer.resize(10)
+        @buffer.size.should == 10
+        @buffer.get_string.should == "require_re"
+        @buffer.resize(12)
+        @buffer.size.should == 12
+        @buffer.get_string.should == "require_re\0\0"
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .for" do
+    context "without a block" do
+      it "disallows resizing, raising IO::Buffer::AccessError" do
+        @buffer = IO::Buffer.for(+"test")
+        -> { @buffer.resize(10) }.should.raise(IO::Buffer::AccessError, "Cannot resize external buffer!")
+      end
+    end
+
+    context "with a block" do
+      it "disallows resizing, raising IO::Buffer::AccessError" do
+        IO::Buffer.for(+'test') do |buffer|
+          -> { buffer.resize(10) }.should.raise(IO::Buffer::AccessError, "Cannot resize external buffer!")
+        end
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .string" do
+    it "disallows resizing, raising IO::Buffer::AccessError" do
+      IO::Buffer.string(4) do |buffer|
+        -> { buffer.resize(10) }.should.raise(IO::Buffer::AccessError, "Cannot resize external buffer!")
+      end
+    end
+  end
+
+  context "with a null buffer" do
+    it "allows resizing a 0-sized buffer, creating a regular buffer according to new size" do
+      @buffer = IO::Buffer.new(0)
+      @buffer.resize(IO::Buffer::PAGE_SIZE)
+      @buffer.size.should == IO::Buffer::PAGE_SIZE
+      @buffer.internal?.should == false
+      @buffer.mapped?.should == true
+    end
+
+    it "allows resizing after a free, creating a regular buffer according to new size" do
+      @buffer = IO::Buffer.for("test")
+      @buffer.free
+      @buffer.resize(10)
+      @buffer.size.should == 10
+      @buffer.internal?.should == true
+      @buffer.mapped?.should == false
+    end
+  end
+
+  it "allows resizing to 0, freeing memory" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.resize(0)
+    @buffer.null?.should == true
+  end
+
+  it "can be called repeatedly" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.resize(10)
+    @buffer.resize(27)
+    @buffer.resize(1)
+    @buffer.size.should == 1
+  end
+
+  it "always clears extra memory" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.set_string("test")
+    # This should not cause a re-allocation, just a technical resizing,
+    # even with very aggressive memory allocation.
+    @buffer.resize(2)
+    @buffer.resize(4)
+    @buffer.get_string.should == "te\0\0"
+  end
+
+  it "is disallowed while locked, raising IO::Buffer::LockedError" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      -> { @buffer.resize(10) }.should.raise(IO::Buffer::LockedError, "Cannot resize locked buffer!")
+    end
+  end
+
+  it "raises ArgumentError if size is negative" do
+    @buffer = IO::Buffer.new(4)
+    -> { @buffer.resize(-1) }.should.raise(ArgumentError, "Size can't be negative!")
+  end
+
+  it "raises TypeError if size is not an Integer" do
+    @buffer = IO::Buffer.new(4)
+    -> { @buffer.resize(nil) }.should.raise(TypeError, "not an Integer")
+    -> { @buffer.resize(10.0) }.should.raise(TypeError, "not an Integer")
+  end
+
+  context "with a slice of a buffer" do
+    # Current behavior of slice resizing seems unintended (it's undocumented, too).
+    # It either creates a completely new buffer, or breaks the slice on size 0.
+    it "needs to be reviewed for spec completeness"
+  end
+end
diff --git a/spec/ruby/core/io/buffer/shared/null_and_empty.rb b/spec/ruby/core/io/buffer/shared/null_and_empty.rb
new file mode 100644
index 0000000000..f8abc5f0fc
--- /dev/null
+++ b/spec/ruby/core/io/buffer/shared/null_and_empty.rb
@@ -0,0 +1,57 @@
+describe :io_buffer_null_and_empty, shared: true do
+  it "is false for a buffer with size > 0" do
+    @buffer = IO::Buffer.new(1)
+    @buffer.send(@method).should == false
+  end
+
+  it "is false for a slice with length > 0" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.slice(1, 2).send(@method).should == false
+  end
+
+  it "is false for a file-mapped buffer" do
+    File.open(__FILE__, "rb") do |file|
+      @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+      @buffer.send(@method).should == false
+    end
+  end
+
+  it "is false for a non-empty String-backed buffer created with .for" do
+    @buffer = IO::Buffer.for("test")
+    @buffer.send(@method).should == false
+  end
+
+  it "is false for a non-empty String-backed buffer created with .string" do
+    IO::Buffer.string(4) do |buffer|
+      buffer.send(@method).should == false
+    end
+  end
+
+  it "is true for a 0-sized buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.send(@method).should == true
+  end
+
+  it "is true for a slice of a 0-sized buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.slice(0, 0).send(@method).should == true
+  end
+
+  it "is true for a freed buffer" do
+    @buffer = IO::Buffer.new(1)
+    @buffer.free
+    @buffer.send(@method).should == true
+  end
+
+  it "is true for a buffer resized to 0" do
+    @buffer = IO::Buffer.new(1)
+    @buffer.resize(0)
+    @buffer.send(@method).should == true
+  end
+
+  it "is true for a buffer whose memory was transferred" do
+    buffer = IO::Buffer.new(1)
+    @buffer = buffer.transfer
+    buffer.send(@method).should == true
+  end
+end
diff --git a/spec/ruby/core/io/buffer/shared_spec.rb b/spec/ruby/core/io/buffer/shared_spec.rb
new file mode 100644
index 0000000000..2cc93e6d08
--- /dev/null
+++ b/spec/ruby/core/io/buffer/shared_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#shared?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer created with SHARED flag" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::INTERNAL | IO::Buffer::SHARED)
+    @buffer.shared?.should == true
+  end
+
+  it "is true for a non-private buffer created with .map" do
+    path = fixture(__dir__, "read_text.txt")
+    file = File.open(path, "r+")
+    @buffer = IO::Buffer.map(file)
+    @buffer.shared?.should == true
+  ensure
+    @buffer.free
+    file.close
+  end
+
+  it "is false for an unshared buffer" do
+    @buffer = IO::Buffer.new(12)
+    @buffer.shared?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.shared?.should == false
+  end
+end
diff --git a/spec/ruby/core/io/buffer/string_spec.rb b/spec/ruby/core/io/buffer/string_spec.rb
new file mode 100644
index 0000000000..4c73ba5e1e
--- /dev/null
+++ b/spec/ruby/core/io/buffer/string_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer.string" do
+  it "creates a modifiable buffer for the duration of the block" do
+    IO::Buffer.string(7) do |buffer|
+      @buffer = buffer
+
+      buffer.size.should == 7
+      buffer.get_string.should == "\0\0\0\0\0\0\0".b
+
+      buffer.set_string("test")
+      buffer.get_string.should == "test\0\0\0"
+    end
+    @buffer.should.null?
+  end
+
+  it "returns contents of the buffer as a binary string" do
+    string =
+      IO::Buffer.string(7) do |buffer|
+        buffer.set_string("ä test")
+      end
+    string.should == "\xC3\xA4 test".b
+  end
+
+  it "creates an external buffer" do
+    IO::Buffer.string(8) do |buffer|
+      buffer.should_not.internal?
+      buffer.should_not.mapped?
+      buffer.should.external?
+
+      buffer.should_not.empty?
+      buffer.should_not.null?
+
+      buffer.should_not.shared?
+      buffer.should_not.private?
+      buffer.should_not.readonly?
+
+      buffer.should_not.locked?
+      buffer.should.valid?
+    end
+  end
+
+  it "returns an empty string if size is 0" do
+    string =
+      IO::Buffer.string(0) do |buffer|
+        buffer.size.should == 0
+      end
+    string.should == ""
+  end
+
+  it "raises ArgumentError if size is negative" do
+    -> { IO::Buffer.string(-1) {} }.should.raise(ArgumentError, "negative string size (or size too big)")
+  end
+
+  it "raises RangeError if size is too large" do
+    -> { IO::Buffer.string(2 ** 232) {} }.should.raise(RangeError, /\Abignum too big to convert into [`']long'\z/)
+  end
+
+  it "raises LocalJumpError if no block is given" do
+    -> { IO::Buffer.string(7) }.should.raise(LocalJumpError, "no block given")
+  end
+end
diff --git a/spec/ruby/core/io/buffer/transfer_spec.rb b/spec/ruby/core/io/buffer/transfer_spec.rb
new file mode 100644
index 0000000000..3bc08998dd
--- /dev/null
+++ b/spec/ruby/core/io/buffer/transfer_spec.rb
@@ -0,0 +1,117 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#transfer" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  context "with a buffer created with .new" do
+    it "transfers internal memory to a new buffer, nullifying the original" do
+      buffer = IO::Buffer.new(4)
+      info = buffer.to_s
+      @buffer = buffer.transfer
+      @buffer.to_s.should == info
+      buffer.null?.should == true
+    end
+
+    it "transfers mapped memory to a new buffer, nullifying the original" do
+      buffer = IO::Buffer.new(4, IO::Buffer::MAPPED)
+      info = buffer.to_s
+      @buffer = buffer.transfer
+      @buffer.to_s.should == info
+      buffer.null?.should == true
+    end
+  end
+
+  context "with a file-backed buffer created with .map" do
+    it "transfers mapped memory to a new buffer, nullifying the original" do
+      File.open(__FILE__, "r") do |file|
+        buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+        info = buffer.to_s
+        @buffer = buffer.transfer
+        @buffer.to_s.should == info
+        buffer.null?.should == true
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .for" do
+    context "without a block" do
+      it "transfers memory to a new buffer, nullifying the original" do
+        buffer = IO::Buffer.for("test")
+        info = buffer.to_s
+        @buffer = buffer.transfer
+        @buffer.to_s.should == info
+        buffer.null?.should == true
+      end
+    end
+
+    context "with a block" do
+      it "transfers memory to a new buffer, breaking the transaction by nullifying the original" do
+        IO::Buffer.for(+"test") do |buffer|
+          info = buffer.to_s
+          @buffer = buffer.transfer
+          @buffer.to_s.should == info
+          buffer.null?.should == true
+        end
+        @buffer.null?.should == false
+      end
+    end
+  end
+
+  context "with a String-backed buffer created with .string" do
+    it "transfers memory to a new buffer, breaking the transaction by nullifying the original" do
+      IO::Buffer.string(4) do |buffer|
+        info = buffer.to_s
+        @buffer = buffer.transfer
+        @buffer.to_s.should == info
+        buffer.null?.should == true
+      end
+      @buffer.null?.should == false
+    end
+  end
+
+  it "allows multiple transfers" do
+    buffer_1 = IO::Buffer.new(4)
+    buffer_2 = buffer_1.transfer
+    @buffer = buffer_2.transfer
+    buffer_1.null?.should == true
+    buffer_2.null?.should == true
+    @buffer.null?.should == false
+  end
+
+  it "is disallowed while locked, raising IO::Buffer::LockedError" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      -> { @buffer.transfer }.should.raise(IO::Buffer::LockedError, "Cannot transfer ownership of locked buffer!")
+    end
+  end
+
+  context "with a slice of a buffer" do
+    it "transfers source to a new slice, not touching the buffer" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.set_string("test")
+      slice = @buffer.slice(0, 2)
+      slice.get_string.should == "te"
+
+      new_slice = slice.transfer
+      slice.null?.should == true
+      new_slice.null?.should == false
+      @buffer.null?.should == false
+
+      new_slice.set_string("ea")
+      @buffer.get_string.should == "east"
+    end
+
+    it "nullifies buffer, invalidating the slice" do
+      buffer = IO::Buffer.new(4)
+      slice = buffer.slice(0, 2)
+      @buffer = buffer.transfer
+
+      slice.null?.should == false
+      slice.valid?.should == false
+      -> { slice.get_string }.should.raise(IO::Buffer::InvalidatedError, "Buffer has been invalidated!")
+    end
+  end
+end
diff --git a/spec/ruby/core/io/buffer/valid_spec.rb b/spec/ruby/core/io/buffer/valid_spec.rb
new file mode 100644
index 0000000000..b84bdd0cfd
--- /dev/null
+++ b/spec/ruby/core/io/buffer/valid_spec.rb
@@ -0,0 +1,99 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#valid?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  # Non-slices are always valid
+  context "with a non-slice buffer" do
+    it "is true for a regular buffer" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.valid?.should == true
+    end
+
+    it "is true for a 0-size buffer" do
+      @buffer = IO::Buffer.new(0)
+      @buffer.valid?.should == true
+    end
+
+    it "is true for a freed buffer" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.free
+      @buffer.valid?.should == true
+    end
+
+    it "is true for a freed file-backed buffer" do
+      File.open(__FILE__, "r") do |file|
+        @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+        @buffer.valid?.should == true
+        @buffer.free
+        @buffer.valid?.should == true
+      end
+    end
+
+    it "is true for a freed string-backed buffer" do
+      @buffer = IO::Buffer.for("hello")
+      @buffer.valid?.should == true
+      @buffer.free
+      @buffer.valid?.should == true
+    end
+  end
+
+  # "A buffer becomes invalid if it is a slice of another buffer (or string)
+  # which has been freed or re-allocated at a different address."
+  context "with a slice" do
+    it "is true for a slice of a live buffer" do
+      @buffer = IO::Buffer.new(4)
+      slice = @buffer.slice(0, 2)
+      slice.valid?.should == true
+    end
+
+    context "when buffer is resized" do
+      it "is false when slice becomes outside the buffer" do
+        @buffer = IO::Buffer.new(4)
+        slice = @buffer.slice(2, 2)
+        @buffer.resize(3)
+        slice.valid?.should == false
+      end
+    end
+
+    it "is false for a slice of a transferred buffer" do
+      buffer = IO::Buffer.new(4)
+      slice = buffer.slice(0, 2)
+      @buffer = buffer.transfer
+      slice.valid?.should == false
+    end
+
+    it "is false for a slice of a freed buffer" do
+      @buffer = IO::Buffer.new(4)
+      slice = @buffer.slice(0, 2)
+      @buffer.free
+      slice.valid?.should == false
+    end
+
+    it "is false for a slice of a freed file-backed buffer" do
+      File.open(__FILE__, "r") do |file|
+        @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+        slice = @buffer.slice(0, 2)
+        slice.valid?.should == true
+        @buffer.free
+        slice.valid?.should == false
+      end
+    end
+
+    it "is true for a slice of a freed string-backed buffer while string is alive" do
+      @buffer = IO::Buffer.for("alive")
+      slice = @buffer.slice(0, 2)
+      slice.valid?.should == true
+      @buffer.free
+      slice.valid?.should == true
+    end
+
+    # There probably should be a test with a garbage-collected string,
+    # but it's not clear how to force that.
+
+    it "needs to be reviewed for spec completeness"
+  end
+end
diff --git a/spec/ruby/core/io/buffer/xor_spec.rb b/spec/ruby/core/io/buffer/xor_spec.rb
new file mode 100644
index 0000000000..9287611f7f
--- /dev/null
+++ b/spec/ruby/core/io/buffer/xor_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+
+describe :io_buffer_xor, shared: true do
+  it "applies the argument buffer as an XOR bit mask across the whole buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\xC9\xBD\xCB\xBB\xCD".b
+        result.free
+      end
+    end
+  end
+
+  it "ignores extra parts of mask if it is longer than source buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F\x00\x00\x00\xFF\xFF") do |mask|
+        result = buffer.send(@method, mask)
+        result.get_string.should == "\xC9\xBD345".b
+        result.free
+      end
+    end
+  end
+
+  it "raises TypeError if mask is not an IO::Buffer" do
+    IO::Buffer.for(+"12345") do |buffer|
+      -> { buffer.send(@method, "\xF8\x8F") }.should.raise(TypeError, "wrong argument type String (expected IO::Buffer)")
+      -> { buffer.send(@method, 0xF8) }.should.raise(TypeError, "wrong argument type Integer (expected IO::Buffer)")
+      -> { buffer.send(@method, nil) }.should.raise(TypeError, "wrong argument type nil (expected IO::Buffer)")
+    end
+  end
+end
+
+describe "IO::Buffer#^" do
+  it_behaves_like :io_buffer_xor, :^
+
+  it "creates a new internal buffer of the same size" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer ^ mask
+        result.should_not.equal? buffer
+        result.should.internal?
+        result.size.should == buffer.size
+        result.free
+        buffer.get_string.should == "12345".b
+      end
+    end
+  end
+end
+
+describe "IO::Buffer#xor!" do
+  it_behaves_like :io_buffer_xor, :xor!
+
+  it "modifies the buffer in place" do
+    IO::Buffer.for(+"12345") do |buffer|
+      IO::Buffer.for(+"\xF8\x8F") do |mask|
+        result = buffer.xor!(mask)
+        result.should.equal? buffer
+        result.should.external?
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/bytes_spec.rb b/spec/ruby/core/io/bytes_spec.rb
deleted file mode 100644
index feeb493566..0000000000
--- a/spec/ruby/core/io/bytes_spec.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-# -*- encoding: utf-8 -*-
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-
-describe "IO#bytes" do
-  before :each do
-    @io = IOSpecs.io_fixture "lines.txt"
-  end
-
-  after :each do
-    @io.close unless @io.closed?
-  end
-
-  it "returns an enumerator of the next bytes from the stream" do
-    enum = @io.bytes
-    enum.should be_an_instance_of(Enumerator)
-    @io.readline.should == "Voici la ligne une.\n"
-    enum.first(5).should == [81, 117, 105, 32, 195]
-  end
-
-  it "yields each byte" do
-    count = 0
-    ScratchPad.record []
-    @io.each_byte do |byte|
-      ScratchPad << byte
-      break if 4 < count += 1
-    end
-
-    ScratchPad.recorded.should == [86, 111, 105, 99, 105]
-  end
-
-  it "raises an IOError on closed stream" do
-    enum = IOSpecs.closed_io.bytes
-    -> { enum.first }.should raise_error(IOError)
-  end
-
-  it "raises an IOError on an enumerator for a stream that has been closed" do
-    enum = @io.bytes
-    enum.first.should == 86
-    @io.close
-    -> { enum.first }.should raise_error(IOError)
-  end
-end
diff --git a/spec/ruby/core/io/chars_spec.rb b/spec/ruby/core/io/chars_spec.rb
deleted file mode 100644
index cd5dbbce4f..0000000000
--- a/spec/ruby/core/io/chars_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-# -*- encoding: utf-8 -*-
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/chars'
-
-describe "IO#chars" do
-  it_behaves_like :io_chars, :chars
-end
-
-describe "IO#chars" do
-  it_behaves_like :io_chars_empty, :chars
-end
diff --git a/spec/ruby/core/io/close_on_exec_spec.rb b/spec/ruby/core/io/close_on_exec_spec.rb
index f837bb56af..28cdb967b9 100644
--- a/spec/ruby/core/io/close_on_exec_spec.rb
+++ b/spec/ruby/core/io/close_on_exec_spec.rb
@@ -14,24 +14,24 @@ describe "IO#close_on_exec=" do
   guard -> { platform_is_not :windows } do
     it "sets the close-on-exec flag if true" do
       @io.close_on_exec = true
-      @io.close_on_exec?.should == true
+      @io.should.close_on_exec?
     end
 
     it "sets the close-on-exec flag if non-false" do
       @io.close_on_exec = :true
-      @io.close_on_exec?.should == true
+      @io.should.close_on_exec?
     end
 
     it "unsets the close-on-exec flag if false" do
       @io.close_on_exec = true
       @io.close_on_exec = false
-      @io.close_on_exec?.should == false
+      @io.should_not.close_on_exec?
     end
 
     it "unsets the close-on-exec flag if nil" do
       @io.close_on_exec = true
       @io.close_on_exec = nil
-      @io.close_on_exec?.should == false
+      @io.should_not.close_on_exec?
     end
 
     it "ensures the IO's file descriptor is closed in exec'ed processes" do
@@ -42,11 +42,7 @@ describe "IO#close_on_exec=" do
 
     it "raises IOError if called on a closed IO" do
       @io.close
-      -> { @io.close_on_exec = true }.should raise_error(IOError)
-    end
-
-    it "returns nil" do
-      @io.send(:close_on_exec=, true).should be_nil
+      -> { @io.close_on_exec = true }.should.raise(IOError)
     end
   end
 end
@@ -64,17 +60,17 @@ describe "IO#close_on_exec?" do
 
   guard -> { platform_is_not :windows } do
     it "returns true by default" do
-      @io.close_on_exec?.should == true
+      @io.should.close_on_exec?
     end
 
     it "returns true if set" do
       @io.close_on_exec = true
-      @io.close_on_exec?.should == true
+      @io.should.close_on_exec?
     end
 
     it "raises IOError if called on a closed IO" do
       @io.close
-      -> { @io.close_on_exec? }.should raise_error(IOError)
+      -> { @io.close_on_exec? }.should.raise(IOError)
     end
   end
 end
diff --git a/spec/ruby/core/io/close_read_spec.rb b/spec/ruby/core/io/close_read_spec.rb
index 6fa4fc8ff8..c505289d72 100644
--- a/spec/ruby/core/io/close_read_spec.rb
+++ b/spec/ruby/core/io/close_read_spec.rb
@@ -4,7 +4,8 @@ require_relative 'fixtures/classes'
 describe "IO#close_read" do
 
   before :each do
-    @io = IO.popen 'cat', "r+"
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, "r+"
     @path = tmp('io.close.txt')
   end
 
@@ -16,26 +17,26 @@ describe "IO#close_read" do
   it "closes the read end of a duplex I/O stream" do
     @io.close_read
 
-    -> { @io.read }.should raise_error(IOError)
+    -> { @io.read }.should.raise(IOError)
   end
 
   it "does nothing on subsequent invocations" do
     @io.close_read
 
-    @io.close_read.should be_nil
+    @io.close_read.should == nil
   end
 
   it "allows subsequent invocation of close" do
     @io.close_read
 
-    -> { @io.close }.should_not raise_error
+    -> { @io.close }.should_not.raise
   end
 
   it "raises an IOError if the stream is writable and not duplexed" do
     io = File.open @path, 'w'
 
     begin
-      -> { io.close_read }.should raise_error(IOError)
+      -> { io.close_read }.should.raise(IOError)
     ensure
       io.close unless io.closed?
     end
@@ -49,12 +50,12 @@ describe "IO#close_read" do
 
     io.close_read
 
-    io.closed?.should == true
+    io.should.closed?
   end
 
   it "does nothing on closed stream" do
     @io.close
 
-    @io.close_read.should be_nil
+    @io.close_read.should == nil
   end
 end
diff --git a/spec/ruby/core/io/close_spec.rb b/spec/ruby/core/io/close_spec.rb
index 21bba32cd8..afd84ba101 100644
--- a/spec/ruby/core/io/close_spec.rb
+++ b/spec/ruby/core/io/close_spec.rb
@@ -14,7 +14,7 @@ describe "IO#close" do
 
   it "closes the stream" do
     @io.close
-    @io.closed?.should == true
+    @io.should.closed?
   end
 
   it "returns nil" do
@@ -23,43 +23,64 @@ describe "IO#close" do
 
   it "raises an IOError reading from a closed IO" do
     @io.close
-    -> { @io.read }.should raise_error(IOError)
+    -> { @io.read }.should.raise(IOError)
   end
 
   it "raises an IOError writing to a closed IO" do
     @io.close
-    -> { @io.write "data" }.should raise_error(IOError)
+    -> { @io.write "data" }.should.raise(IOError)
   end
 
   it 'does not close the stream if autoclose is false' do
     other_io = IO.new(@io.fileno)
     other_io.autoclose = false
     other_io.close
-    -> { @io.write "data" }.should_not raise_error(IOError)
+    -> { @io.write "data" }.should_not.raise(IOError)
   end
 
   it "does nothing if already closed" do
     @io.close
 
-    @io.close.should be_nil
+    @io.close.should == nil
   end
 
-  ruby_version_is '2.5' do
-    it 'raises an IOError with a clear message' do
-      read_io, write_io = IO.pipe
-      going_to_read = false
-      thread = Thread.new do
-        -> do
-          going_to_read = true
-          read_io.read
-        end.should raise_error(IOError, 'stream closed in another thread')
-      end
+  it "does not call the #flush method but flushes the stream internally" do
+    @io.should_not_receive(:flush)
+    @io.close
+    @io.should.closed?
+  end
 
-      Thread.pass until going_to_read && thread.stop?
-      read_io.close
-      thread.join
-      write_io.close
-    end
+  it 'raises an IOError with a clear message' do
+    matching_exception = nil
+
+    -> do
+      IOSpecs::THREAD_CLOSE_RETRIES.times do
+        read_io, write_io = IO.pipe
+        going_to_read = false
+
+        thread = Thread.new do
+          begin
+            going_to_read = true
+            read_io.read
+          rescue IOError => ioe
+            if ioe.message == IOSpecs::THREAD_CLOSE_ERROR_MESSAGE
+              matching_exception = ioe
+            end
+            # try again
+          end
+        end
+
+        # best attempt to ensure the thread is actually blocked on read
+        Thread.pass until going_to_read && thread.stop?
+        sleep(0.001)
+
+        read_io.close
+        thread.join
+        write_io.close
+
+        matching_exception&.tap {|ex| raise ex}
+      end
+    end.should.raise(IOError, IOSpecs::THREAD_CLOSE_ERROR_MESSAGE)
   end
 end
 
@@ -72,7 +93,7 @@ describe "IO#close on an IO.popen stream" do
 
     io.close
 
-    -> { io.pid }.should raise_error(IOError)
+    -> { io.pid }.should.raise(IOError)
   end
 
   it "sets $?" do
diff --git a/spec/ruby/core/io/close_write_spec.rb b/spec/ruby/core/io/close_write_spec.rb
index 75e1577654..60b41505c3 100644
--- a/spec/ruby/core/io/close_write_spec.rb
+++ b/spec/ruby/core/io/close_write_spec.rb
@@ -3,7 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "IO#close_write" do
   before :each do
-    @io = IO.popen 'cat', 'r+'
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, 'r+'
     @path = tmp('io.close.txt')
   end
 
@@ -15,26 +16,26 @@ describe "IO#close_write" do
   it "closes the write end of a duplex I/O stream" do
     @io.close_write
 
-    -> { @io.write "attempt to write" }.should raise_error(IOError)
+    -> { @io.write "attempt to write" }.should.raise(IOError)
   end
 
   it "does nothing on subsequent invocations" do
     @io.close_write
 
-    @io.close_write.should be_nil
+    @io.close_write.should == nil
   end
 
   it "allows subsequent invocation of close" do
     @io.close_write
 
-    -> { @io.close }.should_not raise_error
+    -> { @io.close }.should_not.raise
   end
 
   it "raises an IOError if the stream is readable and not duplexed" do
     io = File.open @path, 'w+'
 
     begin
-      -> { io.close_write }.should raise_error(IOError)
+      -> { io.close_write }.should.raise(IOError)
     ensure
       io.close unless io.closed?
     end
@@ -45,20 +46,23 @@ describe "IO#close_write" do
 
     io.close_write
 
-    io.closed?.should == true
+    io.should.closed?
   end
 
-  it "flushes and closes the write stream" do
-    @io.puts '12345'
+  # Windows didn't have command like cat
+  platform_is_not :windows do
+    it "flushes and closes the write stream" do
+      @io.puts '12345'
 
-    @io.close_write
+      @io.close_write
 
-    @io.read.should == "12345\n"
+      @io.read.should == "12345\n"
+    end
   end
 
   it "does nothing on closed stream" do
     @io.close
 
-    @io.close_write.should be_nil
+    @io.close_write.should == nil
   end
 end
diff --git a/spec/ruby/core/io/closed_spec.rb b/spec/ruby/core/io/closed_spec.rb
index 7316546a0d..1f10858e28 100644
--- a/spec/ruby/core/io/closed_spec.rb
+++ b/spec/ruby/core/io/closed_spec.rb
@@ -11,10 +11,10 @@ describe "IO#closed?" do
   end
 
   it "returns true on closed stream" do
-    IOSpecs.closed_io.closed?.should be_true
+    IOSpecs.closed_io.closed?.should == true
   end
 
   it "returns false on open stream" do
-    @io.closed?.should be_false
+    @io.closed?.should == false
   end
 end
diff --git a/spec/ruby/core/io/codepoints_spec.rb b/spec/ruby/core/io/codepoints_spec.rb
deleted file mode 100644
index 915d99c027..0000000000
--- a/spec/ruby/core/io/codepoints_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-require_relative 'shared/codepoints'
-
-# See redmine #1667
-describe "IO#codepoints" do
-  it_behaves_like :io_codepoints, :codepoints
-end
-
-describe "IO#codepoints" do
-  before :each do
-    @io = IOSpecs.io_fixture "lines.txt"
-  end
-
-  after :each do
-    @io.close unless @io.closed?
-  end
-
-  it "calls the given block" do
-    r = []
-    @io.codepoints { |c| r << c }
-    r[24].should == 232
-    r.last.should == 10
-  end
-end
diff --git a/spec/ruby/core/io/copy_stream_spec.rb b/spec/ruby/core/io/copy_stream_spec.rb
index c541e96e14..31383f9b0f 100644
--- a/spec/ruby/core/io/copy_stream_spec.rb
+++ b/spec/ruby/core/io/copy_stream_spec.rb
@@ -31,7 +31,7 @@ describe :io_copy_stream_to_file, shared: true do
     obj = mock("io_copy_stream_to")
     obj.should_receive(:to_path).and_return(1)
 
-    -> { IO.copy_stream(@object.from, obj) }.should raise_error(TypeError)
+    -> { IO.copy_stream(@object.from, obj) }.should.raise(TypeError)
   end
 end
 
@@ -69,14 +69,17 @@ describe :io_copy_stream_to_io, shared: true do
   end
 
   it "raises an IOError if the destination IO is not open for writing" do
-    @to_io.close
-    @to_io = new_io @to_name, "r"
-    -> { IO.copy_stream @object.from, @to_io }.should raise_error(IOError)
+    to_io = new_io __FILE__, "r"
+    begin
+      -> { IO.copy_stream @object.from, to_io }.should.raise(IOError)
+    ensure
+      to_io.close
+    end
   end
 
   it "does not close the destination IO" do
     IO.copy_stream(@object.from, @to_io)
-    @to_io.closed?.should be_false
+    @to_io.closed?.should == false
   end
 
   it "copies only length bytes when specified" do
@@ -109,7 +112,8 @@ describe "IO.copy_stream" do
   end
 
   after :each do
-    rm_r @to_name, @from_bigfile
+    rm_r @to_name if @to_name
+    rm_r @from_bigfile
   end
 
   describe "from an IO" do
@@ -125,12 +129,12 @@ describe "IO.copy_stream" do
     it "raises an IOError if the source IO is not open for reading" do
       @from_io.close
       @from_io = new_io @from_bigfile, "a"
-      -> { IO.copy_stream @from_io, @to_name }.should raise_error(IOError)
+      -> { IO.copy_stream @from_io, @to_name }.should.raise(IOError)
     end
 
     it "does not close the source IO" do
       IO.copy_stream(@from_io, @to_name)
-      @from_io.closed?.should be_false
+      @from_io.closed?.should == false
     end
 
     platform_is_not :windows do
@@ -164,6 +168,25 @@ describe "IO.copy_stream" do
       it_behaves_like :io_copy_stream_to_io, nil, IOSpecs::CopyStream
       it_behaves_like :io_copy_stream_to_io_with_offset, nil, IOSpecs::CopyStream
     end
+
+    describe "to a Tempfile" do
+      before :all do
+        require 'tempfile'
+      end
+
+      before :each do
+        @to_io = Tempfile.new("rubyspec_copy_stream", encoding: Encoding::BINARY, mode: File::RDONLY)
+        @to_name = @to_io.path
+      end
+
+      after :each do
+        @to_io.close!
+        @to_name = nil # do not rm_r it, already done by Tempfile#close!
+      end
+
+      it_behaves_like :io_copy_stream_to_io, nil, IOSpecs::CopyStream
+      it_behaves_like :io_copy_stream_to_io_with_offset, nil, IOSpecs::CopyStream
+    end
   end
 
   describe "from a file name" do
@@ -183,7 +206,7 @@ describe "IO.copy_stream" do
       obj = mock("io_copy_stream_from")
       obj.should_receive(:to_path).and_return(1)
 
-      -> { IO.copy_stream(obj, @to_name) }.should raise_error(TypeError)
+      -> { IO.copy_stream(obj, @to_name) }.should.raise(TypeError)
     end
 
     describe "to a file name" do
@@ -217,12 +240,12 @@ describe "IO.copy_stream" do
 
     it "does not close the source IO" do
       IO.copy_stream(@from_io, @to_name)
-      @from_io.closed?.should be_false
+      @from_io.closed?.should == false
     end
 
     platform_is_not :windows do
       it "raises an error when an offset is specified" do
-        -> { IO.copy_stream(@from_io, @to_name, 8, 4) }.should raise_error(Errno::ESPIPE)
+        -> { IO.copy_stream(@from_io, @to_name, 8, 4) }.should.raise(Errno::ESPIPE)
       end
     end
 
@@ -278,5 +301,51 @@ describe "IO.copy_stream" do
       IO.copy_stream(@io, @to_name)
     end
 
+    it "does not call #read on the source or #write on the destination if zero length is given" do
+      from = mock("io_copy_stream_to_object_zero_length_read")
+      to = mock("io_copy_stream_to_object_zero_length_write")
+      from.should_not_receive(:read)
+      to.should_not_receive(:write)
+      IO.copy_stream(from, to, 0)
+    end
+  end
+
+  describe "with a destination that does partial reads" do
+    before do
+      @from_out, @from_in = IO.pipe
+      @to_out, @to_in = IO.pipe
+    end
+
+    after do
+      [@from_out, @from_in, @to_out, @to_in].each {|io| io.close rescue nil}
+    end
+
+    it "calls #write repeatedly on the destination Object" do
+      @from_in.write "1234"
+      @from_in.close
+
+      th = Thread.new do
+        IO.copy_stream(@from_out, @to_in)
+      end
+
+      copied = ""
+      4.times do
+        copied += @to_out.read(1)
+      end
+
+      th.join
+
+      copied.should == "1234"
+    end
+
+  end
+end
+
+describe "IO.copy_stream" do
+  it "does not use buffering when writing to STDOUT" do
+    IO.popen([*ruby_exe, fixture(__FILE__ , "copy_in_out.rb")], "r+") do |io|
+      io.write("bar")
+      io.read(3).should == "bar"
+    end
   end
 end
diff --git a/spec/ruby/core/io/dup_spec.rb b/spec/ruby/core/io/dup_spec.rb
index de32c5e347..db4e9fe641 100644
--- a/spec/ruby/core/io/dup_spec.rb
+++ b/spec/ruby/core/io/dup_spec.rb
@@ -25,53 +25,53 @@ describe "IO#dup" do
     @i.fileno.should_not == @f.fileno
   end
 
-quarantine! do # This does not appear to be consistent across platforms
-  it "shares the original stream between the two IOs" do
-    start = @f.pos
-    @i.pos.should == start
+  quarantine! do # This does not appear to be consistent across platforms
+    it "shares the original stream between the two IOs" do
+      start = @f.pos
+      @i.pos.should == start
 
-    s =  "Hello, wo.. wait, where am I?\n"
-    s2 = "<evil voice>       Muhahahaa!"
+      s =  "Hello, wo.. wait, where am I?\n"
+      s2 = "<evil voice>       Muhahahaa!"
 
-    @f.write s
-    @i.pos.should == @f.pos
+      @f.write s
+      @i.pos.should == @f.pos
 
-    @i.rewind
-    @i.gets.should == s
+      @i.rewind
+      @i.gets.should == s
 
-    @i.rewind
-    @i.write s2
+      @i.rewind
+      @i.write s2
 
-    @f.rewind
-    @f.gets.should == "#{s2}\n"
+      @f.rewind
+      @f.gets.should == "#{s2}\n"
+    end
   end
-end
 
   it "allows closing the new IO without affecting the original" do
     @i.close
-    -> { @f.gets }.should_not raise_error(Exception)
+    -> { @f.gets }.should_not.raise(Exception)
 
-    @i.closed?.should == true
-    @f.closed?.should == false
+    @i.should.closed?
+    @f.should_not.closed?
   end
 
   it "allows closing the original IO without affecting the new one" do
     @f.close
-    -> { @i.gets }.should_not raise_error(Exception)
+    -> { @i.gets }.should_not.raise(Exception)
 
-    @i.closed?.should == false
-    @f.closed?.should == true
+    @i.should_not.closed?
+    @f.should.closed?
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.dup }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.dup }.should.raise(IOError)
   end
 
   it "always sets the close-on-exec flag for the new IO object" do
     @f.close_on_exec = true
     dup = @f.dup
     begin
-      dup.close_on_exec?.should == true
+      dup.should.close_on_exec?
     ensure
       dup.close
     end
@@ -79,9 +79,28 @@ end
     @f.close_on_exec = false
     dup = @f.dup
     begin
-      dup.close_on_exec?.should == true
+      dup.should.close_on_exec?
+    ensure
+      dup.close
+    end
+  end
+
+  it "always sets the autoclose flag for the new IO object" do
+    @f.autoclose = true
+    dup = @f.dup
+    begin
+      dup.should.autoclose?
+    ensure
+      dup.close
+    end
+
+    @f.autoclose = false
+    dup = @f.dup
+    begin
+      dup.should.autoclose?
     ensure
       dup.close
+      @f.autoclose = true
     end
   end
 end
diff --git a/spec/ruby/core/io/each_byte_spec.rb b/spec/ruby/core/io/each_byte_spec.rb
index ea618e8c0c..fe299f0fba 100644
--- a/spec/ruby/core/io/each_byte_spec.rb
+++ b/spec/ruby/core/io/each_byte_spec.rb
@@ -12,7 +12,7 @@ describe "IO#each_byte" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.each_byte {} }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.each_byte {} }.should.raise(IOError)
   end
 
   it "yields each byte" do
@@ -28,7 +28,7 @@ describe "IO#each_byte" do
   describe "when no block is given" do
     it "returns an Enumerator" do
       enum = @io.each_byte
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.first(5).should == [86, 111, 105, 99, 105]
     end
 
@@ -52,6 +52,6 @@ describe "IO#each_byte" do
   end
 
   it "returns self on an empty stream" do
-    @io.each_byte { |b| }.should equal(@io)
+    @io.each_byte { |b| }.should.equal?(@io)
   end
 end
diff --git a/spec/ruby/core/io/each_codepoint_spec.rb b/spec/ruby/core/io/each_codepoint_spec.rb
index cddc6b4662..26cc87fc0e 100644
--- a/spec/ruby/core/io/each_codepoint_spec.rb
+++ b/spec/ruby/core/io/each_codepoint_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/codepoints'
 
 # See redmine #1667
 describe "IO#each_codepoint" do
-  it_behaves_like :io_codepoints, :codepoints
+  it_behaves_like :io_codepoints, :each_codepoint
 end
 
 describe "IO#each_codepoint" do
@@ -24,7 +24,7 @@ describe "IO#each_codepoint" do
   end
 
   it "returns self" do
-    @io.each_codepoint { |l| l }.should equal(@io)
+    @io.each_codepoint { |l| l }.should.equal?(@io)
   end
 end
 
@@ -38,6 +38,6 @@ describe "IO#each_codepoint" do
   end
 
   it "raises an exception at incomplete character before EOF when conversion takes place" do
-    -> { @io.each_codepoint {} }.should raise_error(ArgumentError)
+    -> { @io.each_codepoint {} }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/io/eof_spec.rb b/spec/ruby/core/io/eof_spec.rb
index 8fd3c37132..c8955abde0 100644
--- a/spec/ruby/core/io/eof_spec.rb
+++ b/spec/ruby/core/io/eof_spec.rb
@@ -12,13 +12,13 @@ describe "IO#eof?" do
   end
 
   it "returns true on an empty stream that has just been opened" do
-    File.open(@name) { |empty| empty.eof?.should == true }
+    File.open(@name) { |empty| empty.should.eof? }
   end
 
   it "raises IOError on stream not opened for reading" do
     -> do
       File.open(@name, "w") { |f| f.eof? }
-    end.should raise_error(IOError)
+    end.should.raise(IOError)
   end
 end
 
@@ -34,51 +34,51 @@ describe "IO#eof?" do
 
   it "returns false when not at end of file" do
     @io.read 1
-    @io.eof?.should == false
+    @io.should_not.eof?
   end
 
   it "returns true after reading with read with no parameters" do
     @io.read()
-    @io.eof?.should == true
+    @io.should.eof?
   end
 
   it "returns true after reading with read" do
     @io.read(File.size(@name))
-    @io.eof?.should == true
+    @io.should.eof?
   end
 
   it "returns true after reading with sysread" do
     @io.sysread(File.size(@name))
-    @io.eof?.should == true
+    @io.should.eof?
   end
 
   it "returns true after reading with readlines" do
     @io.readlines
-    @io.eof?.should == true
+    @io.should.eof?
   end
 
   it "returns false on just opened non-empty stream" do
-    @io.eof?.should == false
+    @io.should_not.eof?
   end
 
   it "does not consume the data from the stream" do
-    @io.eof?.should == false
+    @io.should_not.eof?
     @io.getc.should == 'V'
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.eof? }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.eof? }.should.raise(IOError)
   end
 
   it "raises IOError on stream closed for reading by close_read" do
     @io.close_read
-    -> { @io.eof? }.should raise_error(IOError)
+    -> { @io.eof? }.should.raise(IOError)
   end
 
   it "returns true on one-byte stream after single-byte read" do
-    File.open(File.dirname(__FILE__) + '/fixtures/one_byte.txt') { |one_byte|
+    File.open(__dir__ + '/fixtures/one_byte.txt') { |one_byte|
       one_byte.read(1)
-      one_byte.eof?.should == true
+      one_byte.should.eof?
     }
   end
 end
@@ -92,16 +92,16 @@ describe "IO#eof?" do
   it "returns true on receiving side of Pipe when writing side is closed" do
     @r, @w = IO.pipe
     @w.close
-    @r.eof?.should == true
+    @r.should.eof?
   end
 
   it "returns false on receiving side of Pipe when writing side wrote some data" do
     @r, @w = IO.pipe
     @w.puts "hello"
-    @r.eof?.should == false
+    @r.should_not.eof?
     @w.close
-    @r.eof?.should == false
+    @r.should_not.eof?
     @r.read
-    @r.eof?.should == true
+    @r.should.eof?
   end
 end
diff --git a/spec/ruby/core/io/external_encoding_spec.rb b/spec/ruby/core/io/external_encoding_spec.rb
index 9666974647..72d246cc2b 100644
--- a/spec/ruby/core/io/external_encoding_spec.rb
+++ b/spec/ruby/core/io/external_encoding_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe :io_external_encoding_write, shared: true do
   describe "when Encoding.default_internal is nil" do
@@ -9,19 +10,19 @@ describe :io_external_encoding_write, shared: true do
     it "returns nil" do
       @io = new_io @name, @object
       Encoding.default_external = Encoding::IBM437
-      @io.external_encoding.should be_nil
+      @io.external_encoding.should == nil
     end
 
     it "returns the external encoding specified when the instance was created" do
       @io = new_io @name, "#{@object}:ibm866"
       Encoding.default_external = Encoding::IBM437
-      @io.external_encoding.should equal(Encoding::IBM866)
+      @io.external_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "returns the encoding set by #set_encoding" do
       @io = new_io @name, "#{@object}:ibm866"
       @io.set_encoding Encoding::EUC_JP, nil
-      @io.external_encoding.should equal(Encoding::EUC_JP)
+      @io.external_encoding.should.equal?(Encoding::EUC_JP)
     end
   end
 
@@ -34,19 +35,19 @@ describe :io_external_encoding_write, shared: true do
     it "returns the value of Encoding.default_external when the instance was created" do
       @io = new_io @name, @object
       Encoding.default_external = Encoding::UTF_8
-      @io.external_encoding.should equal(Encoding::IBM437)
+      @io.external_encoding.should.equal?(Encoding::IBM437)
     end
 
     it "returns the external encoding specified when the instance was created" do
       @io = new_io @name, "#{@object}:ibm866"
       Encoding.default_external = Encoding::IBM437
-      @io.external_encoding.should equal(Encoding::IBM866)
+      @io.external_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "returns the encoding set by #set_encoding" do
       @io = new_io @name, "#{@object}:ibm866"
       @io.set_encoding Encoding::EUC_JP, nil
-      @io.external_encoding.should equal(Encoding::EUC_JP)
+      @io.external_encoding.should.equal?(Encoding::EUC_JP)
     end
   end
 
@@ -59,19 +60,19 @@ describe :io_external_encoding_write, shared: true do
     it "returns the value of Encoding.default_external when the instance was created" do
       @io = new_io @name, @object
       Encoding.default_external = Encoding::UTF_8
-      @io.external_encoding.should equal(Encoding::IBM866)
+      @io.external_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "returns the external encoding specified when the instance was created" do
       @io = new_io @name, "#{@object}:ibm866"
       Encoding.default_external = Encoding::IBM437
-      @io.external_encoding.should equal(Encoding::IBM866)
+      @io.external_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "returns the encoding set by #set_encoding" do
       @io = new_io @name, "#{@object}:ibm866"
       @io.set_encoding Encoding::EUC_JP, nil
-      @io.external_encoding.should equal(Encoding::EUC_JP)
+      @io.external_encoding.should.equal?(Encoding::EUC_JP)
     end
   end
 end
@@ -93,6 +94,12 @@ describe "IO#external_encoding" do
     rm_r @name
   end
 
+  it "can be retrieved from a closed stream" do
+    io = IOSpecs.io_fixture("lines.txt", "r")
+    io.close
+    io.external_encoding.should.equal?(Encoding.default_external)
+  end
+
   describe "with 'r' mode" do
     describe "when Encoding.default_internal is nil" do
       before :each do
@@ -102,25 +109,25 @@ describe "IO#external_encoding" do
 
       it "returns Encoding.default_external if the external encoding is not set" do
         @io = new_io @name, "r"
-        @io.external_encoding.should equal(Encoding::IBM866)
+        @io.external_encoding.should.equal?(Encoding::IBM866)
       end
 
       it "returns Encoding.default_external when that encoding is changed after the instance is created" do
         @io = new_io @name, "r"
         Encoding.default_external = Encoding::IBM437
-        @io.external_encoding.should equal(Encoding::IBM437)
+        @io.external_encoding.should.equal?(Encoding::IBM437)
       end
 
       it "returns the external encoding specified when the instance was created" do
         @io = new_io @name, "r:utf-8"
         Encoding.default_external = Encoding::IBM437
-        @io.external_encoding.should equal(Encoding::UTF_8)
+        @io.external_encoding.should.equal?(Encoding::UTF_8)
       end
 
       it "returns the encoding set by #set_encoding" do
         @io = new_io @name, "r:utf-8"
         @io.set_encoding Encoding::EUC_JP, nil
-        @io.external_encoding.should equal(Encoding::EUC_JP)
+        @io.external_encoding.should.equal?(Encoding::EUC_JP)
       end
     end
 
@@ -133,19 +140,19 @@ describe "IO#external_encoding" do
       it "returns the value of Encoding.default_external when the instance was created" do
         @io = new_io @name, "r"
         Encoding.default_external = Encoding::IBM437
-        @io.external_encoding.should equal(Encoding::IBM866)
+        @io.external_encoding.should.equal?(Encoding::IBM866)
       end
 
       it "returns the external encoding specified when the instance was created" do
         @io = new_io @name, "r:utf-8"
         Encoding.default_external = Encoding::IBM437
-        @io.external_encoding.should equal(Encoding::UTF_8)
+        @io.external_encoding.should.equal?(Encoding::UTF_8)
       end
 
       it "returns the encoding set by #set_encoding" do
         @io = new_io @name, "r:utf-8"
         @io.set_encoding Encoding::EUC_JP, nil
-        @io.external_encoding.should equal(Encoding::EUC_JP)
+        @io.external_encoding.should.equal?(Encoding::EUC_JP)
       end
     end
 
@@ -159,13 +166,13 @@ describe "IO#external_encoding" do
       it "returns the external encoding specified when the instance was created" do
         @io = new_io @name, "r:utf-8"
         Encoding.default_external = Encoding::IBM437
-        @io.external_encoding.should equal(Encoding::UTF_8)
+        @io.external_encoding.should.equal?(Encoding::UTF_8)
       end
 
       it "returns the encoding set by #set_encoding" do
         @io = new_io @name, "r:utf-8"
         @io.set_encoding Encoding::EUC_JP, nil
-        @io.external_encoding.should equal(Encoding::EUC_JP)
+        @io.external_encoding.should.equal?(Encoding::EUC_JP)
       end
     end
   end
@@ -173,12 +180,12 @@ describe "IO#external_encoding" do
   describe "with 'rb' mode" do
     it "returns Encoding::BINARY" do
       @io = new_io @name, "rb"
-      @io.external_encoding.should equal(Encoding::BINARY)
+      @io.external_encoding.should.equal?(Encoding::BINARY)
     end
 
     it "returns the external encoding specified by the mode argument" do
       @io = new_io @name, "rb:ibm437"
-      @io.external_encoding.should equal(Encoding::IBM437)
+      @io.external_encoding.should.equal?(Encoding::IBM437)
     end
   end
 
@@ -193,12 +200,12 @@ describe "IO#external_encoding" do
   describe "with 'wb' mode" do
     it "returns Encoding::BINARY" do
       @io = new_io @name, "wb"
-      @io.external_encoding.should equal(Encoding::BINARY)
+      @io.external_encoding.should.equal?(Encoding::BINARY)
     end
 
     it "returns the external encoding specified by the mode argument" do
       @io = new_io @name, "wb:ibm437"
-      @io.external_encoding.should equal(Encoding::IBM437)
+      @io.external_encoding.should.equal?(Encoding::IBM437)
     end
   end
 
diff --git a/spec/ruby/core/io/fcntl_spec.rb b/spec/ruby/core/io/fcntl_spec.rb
index 30b4876fe3..be6d06c672 100644
--- a/spec/ruby/core/io/fcntl_spec.rb
+++ b/spec/ruby/core/io/fcntl_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "IO#fcntl" do
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.fcntl(5, 5) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.fcntl(5, 5) }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/fileno_spec.rb b/spec/ruby/core/io/fileno_spec.rb
index 647609bf42..22fd68d166 100644
--- a/spec/ruby/core/io/fileno_spec.rb
+++ b/spec/ruby/core/io/fileno_spec.rb
@@ -7,6 +7,6 @@ describe "IO#fileno" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.fileno }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.fileno }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/fixtures/classes.rb b/spec/ruby/core/io/fixtures/classes.rb
index 460dd62387..204a2a101b 100644
--- a/spec/ruby/core/io/fixtures/classes.rb
+++ b/spec/ruby/core/io/fixtures/classes.rb
@@ -1,9 +1,24 @@
 # -*- encoding: utf-8 -*-
 
 module IOSpecs
+  THREAD_CLOSE_RETRIES = 10
+  THREAD_CLOSE_ERROR_MESSAGE = 'stream closed in another thread'
+
   class SubIO < IO
   end
 
+  class SubIOWithRedefinedNew < IO
+    def self.new(...)
+      ScratchPad << :redefined_new_called
+      super
+    end
+
+    def initialize(...)
+      ScratchPad << :call_original_initialize
+      super
+    end
+  end
+
   def self.collector
     Proc.new { |x| ScratchPad << x }
   end
@@ -105,6 +120,14 @@ module IOSpecs
       "linha ", "cinco.\nHere ", "is ", "line ", "six.\n" ]
   end
 
+  def self.lines_space_separator_without_trailing_spaces
+    [ "Voici", "la", "ligne", "une.\nQui",
+      "\303\250", "la", "linea", "due.\n\n\nAqu\303\255",
+      "est\303\241", "la", "l\303\255nea", "tres.\nHier",
+      "ist", "Zeile", "vier.\n\nEst\303\241", "aqui", "a",
+      "linha", "cinco.\nHere", "is", "line", "six.\n" ]
+  end
+
   def self.lines_arbitrary_separator
     [ "Voici la ligne une.\nQui \303\250",
       " la linea due.\n\n\nAqu\303\255 est\303\241 la l\303\255nea tres.\nHier ist Zeile vier.\n\nEst\303\241 aqui a linha cinco.\nHere is line six.\n" ]
@@ -116,6 +139,12 @@ module IOSpecs
       "Est\303\241 aqui a linha cinco.\nHere is line six.\n" ]
   end
 
+  def self.paragraphs_without_trailing_new_line_characters
+    [ "Voici la ligne une.\nQui \303\250 la linea due.",
+      "Aqu\303\255 est\303\241 la l\303\255nea tres.\nHier ist Zeile vier.",
+      "Est\303\241 aqui a linha cinco.\nHere is line six.\n" ]
+  end
+
   # Creates an IO instance for an existing fixture file. The
   # file should obviously not be deleted.
   def self.io_fixture(name, mode = "r:utf-8")
@@ -164,7 +193,7 @@ module IOSpecs
       @io = io
     end
 
-    def read(size, buf=nil)
+    def read(size, buf)
       @io.read size, buf
     end
 
@@ -178,7 +207,7 @@ module IOSpecs
       @io = io
     end
 
-    def readpartial(size, buf=nil)
+    def readpartial(size, buf)
       @io.readpartial size, buf
     end
 
diff --git a/spec/ruby/core/io/fixtures/copy_in_out.rb b/spec/ruby/core/io/fixtures/copy_in_out.rb
new file mode 100644
index 0000000000..b9d4085a47
--- /dev/null
+++ b/spec/ruby/core/io/fixtures/copy_in_out.rb
@@ -0,0 +1,2 @@
+STDOUT.sync = false
+IO.copy_stream(STDIN, STDOUT)
diff --git a/spec/ruby/core/io/flush_spec.rb b/spec/ruby/core/io/flush_spec.rb
index 34cf42c425..4c3e8d12af 100644
--- a/spec/ruby/core/io/flush_spec.rb
+++ b/spec/ruby/core/io/flush_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "IO#flush" do
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.flush }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.flush }.should.raise(IOError)
   end
 
   describe "on a pipe" do
@@ -19,18 +19,18 @@ describe "IO#flush" do
       end
     end
 
-    # [ruby-core:90895] MJIT worker may leave fd open in a forked child.
-    # For instance, MJIT creates a worker before @r.close with fork(), @r.close happens,
-    # and the MJIT worker keeps the pipe open until the worker execve().
-    # TODO: consider acquiring GVL from MJIT worker.
-    guard_not -> { defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? } do
+    # [ruby-core:90895] RJIT worker may leave fd open in a forked child.
+    # For instance, RJIT creates a worker before @r.close with fork(), @r.close happens,
+    # and the RJIT worker keeps the pipe open until the worker execve().
+    # TODO: consider acquiring GVL from RJIT worker.
+    guard_not -> { defined?(RubyVM::RJIT) && RubyVM::RJIT.enabled? } do
       it "raises Errno::EPIPE if sync=false and the read end is closed" do
         @w.sync = false
         @w.write "foo"
         @r.close
 
-        -> { @w.flush }.should raise_error(Errno::EPIPE, /Broken pipe/)
-        -> { @w.close }.should raise_error(Errno::EPIPE, /Broken pipe/)
+        -> { @w.flush }.should.raise(Errno::EPIPE, /Broken pipe/)
+        -> { @w.close }.should.raise(Errno::EPIPE, /Broken pipe/)
       end
     end
   end
diff --git a/spec/ruby/core/io/foreach_spec.rb b/spec/ruby/core/io/foreach_spec.rb
index c2276cf544..015988f9fb 100644
--- a/spec/ruby/core/io/foreach_spec.rb
+++ b/spec/ruby/core/io/foreach_spec.rb
@@ -14,31 +14,46 @@ describe "IO.foreach" do
     IO.foreach(@name) { $..should == @count += 1 }
   end
 
-  describe "when the filename starts with |" do
-    it "gets data from the standard out of the subprocess" do
-      cmd = "|sh -c 'echo hello;echo line2'"
-      platform_is :windows do
-        cmd = "|cmd.exe /C echo hello&echo line2"
+  ruby_version_is ""..."4.0" do
+    describe "when the filename starts with |" do
+      it "gets data from the standard out of the subprocess" do
+        cmd = "|sh -c 'echo hello;echo line2'"
+        platform_is :windows do
+          cmd = "|cmd.exe /C echo hello&echo line2"
+        end
+
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          IO.foreach(cmd) { |l| ScratchPad << l }
+        end
+        ScratchPad.recorded.should == ["hello\n", "line2\n"]
       end
-      IO.foreach(cmd) { |l| ScratchPad << l }
-      ScratchPad.recorded.should == ["hello\n", "line2\n"]
-    end
 
-    platform_is_not :windows do
-      it "gets data from a fork when passed -" do
-        parent_pid = $$
+      platform_is_not :windows do
+        it "gets data from a fork when passed -" do
+          parent_pid = $$
 
-        IO.foreach("|-") { |l| ScratchPad << l }
+          suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+            IO.foreach("|-") { |l| ScratchPad << l }
+          end
 
-        if $$ == parent_pid
-          ScratchPad.recorded.should == ["hello\n", "from a fork\n"]
-        else # child
-          puts "hello"
-          puts "from a fork"
-          exit!
+          if $$ == parent_pid
+            ScratchPad.recorded.should == ["hello\n", "from a fork\n"]
+          else # child
+            puts "hello"
+            puts "from a fork"
+            exit!
+          end
         end
       end
     end
+
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation given a path with a pipe" do
+      cmd = "|echo ok"
+      -> {
+        IO.foreach(cmd).to_a
+      }.should complain(/IO process creation with a leading '\|'/)
+    end
   end
 end
 
@@ -58,12 +73,12 @@ describe "IO.foreach" do
   it "sets $_ to nil" do
     $_ = "test"
     IO.foreach(@name) { }
-    $_.should be_nil
+    $_.should == nil
   end
 
   describe "when no block is given" do
     it "returns an Enumerator" do
-      IO.foreach(@name).should be_an_instance_of(Enumerator)
+      IO.foreach(@name).should.instance_of?(Enumerator)
       IO.foreach(@name).to_a.should == IOSpecs.lines
     end
 
diff --git a/spec/ruby/core/io/fsync_spec.rb b/spec/ruby/core/io/fsync_spec.rb
index 6e6123de94..0317cbc805 100644
--- a/spec/ruby/core/io/fsync_spec.rb
+++ b/spec/ruby/core/io/fsync_spec.rb
@@ -12,7 +12,7 @@ describe "IO#fsync" do
   end
 
   it "raises an IOError on closed stream" do
-    -> { IOSpecs.closed_io.fsync }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.fsync }.should.raise(IOError)
   end
 
   it "writes the buffered data to permanent storage" do
diff --git a/spec/ruby/core/io/getbyte_spec.rb b/spec/ruby/core/io/getbyte_spec.rb
index 6ba8f0a3e0..668d81519c 100644
--- a/spec/ruby/core/io/getbyte_spec.rb
+++ b/spec/ruby/core/io/getbyte_spec.rb
@@ -23,7 +23,7 @@ describe "IO#getbyte" do
   end
 
   it "raises an IOError on closed stream" do
-    -> { IOSpecs.closed_io.getbyte }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.getbyte }.should.raise(IOError)
   end
 end
 
@@ -40,3 +40,19 @@ describe "IO#getbyte" do
     @io.getbyte.should == nil
   end
 end
+
+describe "IO#getbyte" do
+  before :each do
+    @name = tmp("io_getbyte.txt")
+    @io = new_io(@name, 'w')
+  end
+
+  after :each do
+    @io.close if @io
+    rm_r @name if @name
+  end
+
+  it "raises an IOError if the stream is not readable" do
+    -> { @io.getbyte }.should.raise(IOError)
+  end
+end
diff --git a/spec/ruby/core/io/getc_spec.rb b/spec/ruby/core/io/getc_spec.rb
index 3949b5cb28..3be86203c0 100644
--- a/spec/ruby/core/io/getc_spec.rb
+++ b/spec/ruby/core/io/getc_spec.rb
@@ -19,11 +19,11 @@ describe "IO#getc" do
 
   it "returns nil when invoked at the end of the stream" do
     @io.read
-    @io.getc.should be_nil
+    @io.getc.should == nil
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.getc }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.getc }.should.raise(IOError)
   end
 end
 
@@ -37,6 +37,6 @@ describe "IO#getc" do
   end
 
   it "returns nil on empty stream" do
-    @io.getc.should be_nil
+    @io.getc.should == nil
   end
 end
diff --git a/spec/ruby/core/io/gets_spec.rb b/spec/ruby/core/io/gets_spec.rb
index 8f6ec0dfc7..ce3ee73b94 100644
--- a/spec/ruby/core/io/gets_spec.rb
+++ b/spec/ruby/core/io/gets_spec.rb
@@ -24,13 +24,19 @@ describe "IO#gets" do
     end
   end
 
+  it "sets $_ to nil after the last line has been read" do
+    while @io.gets
+    end
+    $_.should == nil
+  end
+
   it "returns nil if called at the end of the stream" do
     IOSpecs.lines.length.times { @io.gets }
     @io.gets.should == nil
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.gets }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.gets }.should.raise(IOError)
   end
 
   describe "with no separator" do
@@ -38,12 +44,6 @@ describe "IO#gets" do
       IOSpecs.lines.each { |line| line.should == @io.gets }
     end
 
-    it "returns tainted strings" do
-      while line = @io.gets
-        line.tainted?.should == true
-      end
-    end
-
     it "updates lineno with each invocation" do
       while @io.gets
         @io.lineno.should == @count += 1
@@ -62,12 +62,6 @@ describe "IO#gets" do
       @io.gets(nil).should == IOSpecs.lines.join("")
     end
 
-    it "returns tainted strings" do
-      while line = @io.gets(nil)
-        line.tainted?.should == true
-      end
-    end
-
     it "updates lineno with each invocation" do
       while @io.gets(nil)
         @io.lineno.should == @count += 1
@@ -96,12 +90,6 @@ describe "IO#gets" do
       @io.gets.should == IOSpecs.lines[4]
     end
 
-    it "returns tainted strings" do
-      while line = @io.gets("")
-        line.tainted?.should == true
-      end
-    end
-
     it "updates lineno with each invocation" do
       while @io.gets("")
         @io.lineno.should == @count += 1
@@ -120,12 +108,6 @@ describe "IO#gets" do
       @io.gets("la linea").should == "Voici la ligne une.\nQui \303\250 la linea"
     end
 
-    it "returns tainted strings" do
-      while line = @io.gets("la")
-        line.tainted?.should == true
-      end
-    end
-
     it "updates lineno with each invocation" do
       while (@io.gets("la"))
         @io.lineno.should == @count += 1
@@ -137,12 +119,49 @@ describe "IO#gets" do
         $..should == @count += 1
       end
     end
+
+    describe "that consists of multiple bytes" do
+      platform_is_not :windows do
+        it "should match the separator even if the buffer is filled over successive reads" do
+          IO.pipe do |read, write|
+
+            # Write part of the string with the separator split between two write calls. We want
+            # the read to intertwine such that when the read starts the full data isn't yet
+            # available in the buffer.
+            write.write("Aquí está la línea tres\r\n")
+
+            t = Thread.new do
+              # Continue reading until the separator is encountered or the pipe is closed.
+              read.gets("\r\n\r\n")
+            end
+
+            # Write the other half of the separator, which should cause the `gets` call to now
+            # match. Explicitly close the pipe for good measure so a bug in `gets` doesn't block forever.
+            Thread.pass until t.stop?
+
+            write.write("\r\nelse\r\n\r\n")
+            write.close
+
+            t.value.bytes.should == "Aquí está la línea tres\r\n\r\n".bytes
+            read.read(8).bytes.should == "else\r\n\r\n".bytes
+          end
+        end
+      end
+    end
   end
 
   describe "when passed chomp" do
     it "returns the first line without a trailing newline character" do
       @io.gets(chomp: true).should == IOSpecs.lines_without_newline_characters[0]
     end
+
+    it "raises exception when options passed as Hash" do
+      -> { @io.gets({ chomp: true }) }.should.raise(TypeError)
+
+      -> {
+        @io.gets("\n", 1, { chomp: true })
+      }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 0..2)")
+    end
   end
 end
 
@@ -156,11 +175,11 @@ describe "IO#gets" do
   end
 
   it "raises an IOError if the stream is opened for append only" do
-    -> { File.open(@name, "a:utf-8") { |f| f.gets } }.should raise_error(IOError)
+    -> { File.open(@name, "a:utf-8") { |f| f.gets } }.should.raise(IOError)
   end
 
   it "raises an IOError if the stream is opened for writing only" do
-    -> { File.open(@name, "w:utf-8") { |f| f.gets } }.should raise_error(IOError)
+    -> { File.open(@name, "w:utf-8") { |f| f.gets } }.should.raise(IOError)
   end
 end
 
@@ -224,6 +243,16 @@ describe "IO#gets" do
   it "reads all bytes when pass a separator and reading more than all bytes" do
     @io.gets("\t", 100).should == "one\n\ntwo\n\nthree\nfour\n"
   end
+
+  it "returns empty string when 0 passed as a limit" do
+    @io.gets(0).should == ""
+    @io.gets(nil, 0).should == ""
+    @io.gets("", 0).should == ""
+  end
+
+  it "does not accept limit that doesn't fit in a C off_t" do
+    -> { @io.gets(2**128) }.should.raise(RangeError)
+  end
 end
 
 describe "IO#gets" do
@@ -309,11 +338,11 @@ describe "IO#gets" do
     @io.gets.encoding.should == Encoding::BINARY
   end
 
-  it "transcodes to internal encoding if the IO object's external encoding is BINARY" do
+  it "ignores the internal encoding if the IO object's external encoding is BINARY" do
     Encoding.default_external = Encoding::BINARY
     Encoding.default_internal = Encoding::UTF_8
     @io = new_io @name, 'r'
     @io.set_encoding Encoding::BINARY, Encoding::UTF_8
-    @io.gets.encoding.should == Encoding::UTF_8
+    @io.gets.encoding.should == Encoding::BINARY
   end
 end
diff --git a/spec/ruby/core/io/initialize_spec.rb b/spec/ruby/core/io/initialize_spec.rb
index c0d84765a8..3425e5ac37 100644
--- a/spec/ruby/core/io/initialize_spec.rb
+++ b/spec/ruby/core/io/initialize_spec.rb
@@ -13,7 +13,7 @@ describe "IO#initialize" do
     rm_r @name
   end
 
-  it "reassociates the IO instance with the new descriptor when passed a Fixnum" do
+  it "reassociates the IO instance with the new descriptor when passed an Integer" do
     fd = new_fd @name, "r:utf-8"
     @io.send :initialize, fd, 'r'
     @io.fileno.should == fd
@@ -27,23 +27,34 @@ describe "IO#initialize" do
     @io.fileno.should == fd
   end
 
+  it "accepts options as keyword arguments" do
+    fd = new_fd @name, "w:utf-8"
+
+    @io.send(:initialize, fd, "w", flags: File::CREAT)
+    @io.fileno.should == fd
+
+    -> {
+      @io.send(:initialize, fd, "w", {flags: File::CREAT})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 1..2)")
+  end
+
   it "raises a TypeError when passed an IO" do
-    -> { @io.send :initialize, STDOUT, 'w' }.should raise_error(TypeError)
+    -> { @io.send :initialize, STDOUT, 'w' }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { @io.send :initialize, nil, 'w' }.should raise_error(TypeError)
+    -> { @io.send :initialize, nil, 'w' }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { @io.send :initialize, "4", 'w' }.should raise_error(TypeError)
+    -> { @io.send :initialize, "4", 'w' }.should.raise(TypeError)
   end
 
   it "raises IOError on closed stream" do
-    -> { @io.send :initialize, IOSpecs.closed_io.fileno }.should raise_error(IOError)
+    -> { @io.send :initialize, IOSpecs.closed_io.fileno }.should.raise(IOError)
   end
 
   it "raises an Errno::EBADF when given an invalid file descriptor" do
-    -> { @io.send :initialize, -1, 'w' }.should raise_error(Errno::EBADF)
+    -> { @io.send :initialize, -1, 'w' }.should.raise(Errno::EBADF)
   end
 end
diff --git a/spec/ruby/core/io/inspect_spec.rb b/spec/ruby/core/io/inspect_spec.rb
index c653c307c4..37dc459f22 100644
--- a/spec/ruby/core/io/inspect_spec.rb
+++ b/spec/ruby/core/io/inspect_spec.rb
@@ -8,13 +8,13 @@ describe "IO#inspect" do
 
   it "contains the file descriptor number" do
     @r, @w = IO.pipe
-    @r.inspect.should include("fd #{@r.fileno}")
+    @r.inspect.should.include?("fd #{@r.fileno}")
   end
 
   it "contains \"(closed)\" if the stream is closed" do
     @r, @w = IO.pipe
     @r.close
-    @r.inspect.should include("(closed)")
+    @r.inspect.should.include?("(closed)")
   end
 
   it "reports IO as its Method object's owner" do
diff --git a/spec/ruby/core/io/internal_encoding_spec.rb b/spec/ruby/core/io/internal_encoding_spec.rb
index 10ebf28707..9963a93f33 100644
--- a/spec/ruby/core/io/internal_encoding_spec.rb
+++ b/spec/ruby/core/io/internal_encoding_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe :io_internal_encoding, shared: true do
   describe "when Encoding.default_internal is not set" do
@@ -8,25 +9,25 @@ describe :io_internal_encoding, shared: true do
 
     it "returns nil if the internal encoding is not set" do
       @io = new_io @name, @object
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
 
     it "returns nil if Encoding.default_internal is changed after the instance is created" do
       @io = new_io @name, @object
       Encoding.default_internal = Encoding::IBM437
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
 
     it "returns the value set when the instance was created" do
       @io = new_io @name, "#{@object}:utf-8:euc-jp"
       Encoding.default_internal = Encoding::IBM437
-      @io.internal_encoding.should equal(Encoding::EUC_JP)
+      @io.internal_encoding.should.equal?(Encoding::EUC_JP)
     end
 
     it "returns the value set by #set_encoding" do
       @io = new_io @name, @object
       @io.set_encoding(Encoding::US_ASCII, Encoding::IBM437)
-      @io.internal_encoding.should equal(Encoding::IBM437)
+      @io.internal_encoding.should.equal?(Encoding::IBM437)
     end
   end
 
@@ -38,13 +39,13 @@ describe :io_internal_encoding, shared: true do
 
     it "returns nil" do
       @io = new_io @name, @object
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
 
     it "returns nil regardless of Encoding.default_internal changes" do
       @io = new_io @name, @object
       Encoding.default_internal = Encoding::IBM437
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
   end
 
@@ -56,41 +57,41 @@ describe :io_internal_encoding, shared: true do
 
     it "returns the value of Encoding.default_internal when the instance was created if the internal encoding is not set" do
       @io = new_io @name, @object
-      @io.internal_encoding.should equal(Encoding::IBM866)
+      @io.internal_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "does not change when Encoding.default_internal is changed" do
       @io = new_io @name, @object
       Encoding.default_internal = Encoding::IBM437
-      @io.internal_encoding.should equal(Encoding::IBM866)
+      @io.internal_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "returns the internal encoding set when the instance was created" do
       @io = new_io @name, "#{@object}:utf-8:euc-jp"
-      @io.internal_encoding.should equal(Encoding::EUC_JP)
+      @io.internal_encoding.should.equal?(Encoding::EUC_JP)
     end
 
     it "does not change when set and Encoding.default_internal is changed" do
       @io = new_io @name, "#{@object}:utf-8:euc-jp"
       Encoding.default_internal = Encoding::IBM437
-      @io.internal_encoding.should equal(Encoding::EUC_JP)
+      @io.internal_encoding.should.equal?(Encoding::EUC_JP)
     end
 
     it "returns the value set by #set_encoding" do
       @io = new_io @name, @object
       @io.set_encoding(Encoding::US_ASCII, Encoding::IBM437)
-      @io.internal_encoding.should equal(Encoding::IBM437)
+      @io.internal_encoding.should.equal?(Encoding::IBM437)
     end
 
     it "returns nil when Encoding.default_external is BINARY and the internal encoding is not set" do
       Encoding.default_external = Encoding::BINARY
       @io = new_io @name, @object
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
 
     it "returns nil when the external encoding is BINARY and the internal encoding is not set" do
       @io = new_io @name, "#{@object}:binary"
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
   end
 end
@@ -112,6 +113,12 @@ describe "IO#internal_encoding" do
     Encoding.default_internal = @internal
   end
 
+  it "can be retrieved from a closed stream" do
+    io = IOSpecs.io_fixture("lines.txt", "r")
+    io.close
+    io.internal_encoding.should.equal?(Encoding.default_internal)
+  end
+
   describe "with 'r' mode" do
     it_behaves_like :io_internal_encoding, nil, "r"
   end
diff --git a/spec/ruby/core/io/ioctl_spec.rb b/spec/ruby/core/io/ioctl_spec.rb
index e819a217a8..15a5d6ec22 100644
--- a/spec/ruby/core/io/ioctl_spec.rb
+++ b/spec/ruby/core/io/ioctl_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "IO#ioctl" do
   platform_is_not :windows do
     it "raises IOError on closed stream" do
-      -> { IOSpecs.closed_io.ioctl(5, 5) }.should raise_error(IOError)
+      -> { IOSpecs.closed_io.ioctl(5, 5) }.should.raise(IOError)
     end
   end
 
@@ -12,20 +12,20 @@ describe "IO#ioctl" do
     guard -> { RUBY_PLATFORM.include?("86") } do # x86 / x86_64
       it "resizes an empty String to match the output size" do
         File.open(__FILE__, 'r') do |f|
-          buffer = ''
+          buffer = +''
           # FIONREAD in /usr/include/asm-generic/ioctls.h
           f.ioctl 0x541B, buffer
-          buffer.unpack('I').first.should be_kind_of(Integer)
+          buffer.unpack('I').first.should.is_a?(Integer)
         end
       end
     end
 
-    it "raises an Errno error when ioctl fails" do
+    it "raises a system call error when ioctl fails" do
       File.open(__FILE__, 'r') do |f|
         -> {
           # TIOCGWINSZ in /usr/include/asm-generic/ioctls.h
           f.ioctl 0x5413, nil
-        }.should raise_error(Errno::ENOTTY)
+        }.should.raise(SystemCallError)
       end
     end
   end
diff --git a/spec/ruby/core/io/lineno_spec.rb b/spec/ruby/core/io/lineno_spec.rb
index 3d1b2275cc..93b505652a 100644
--- a/spec/ruby/core/io/lineno_spec.rb
+++ b/spec/ruby/core/io/lineno_spec.rb
@@ -11,7 +11,26 @@ describe "IO#lineno" do
   end
 
   it "raises an IOError on a closed stream" do
-    -> { IOSpecs.closed_io.lineno }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.lineno }.should.raise(IOError)
+  end
+
+  it "raises an IOError on a write-only stream" do
+    name = tmp("io_lineno.txt")
+    begin
+      File.open(name, 'w') do |f|
+        -> { f.lineno }.should.raise(IOError)
+      end
+    ensure
+      rm_r name
+    end
+  end
+
+  it "raises an IOError on a duplexed stream with the read side closed" do
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    IO.popen(cmd, 'r+') do |p|
+      p.close_read
+      -> { p.lineno }.should.raise(IOError)
+    end
   end
 
   it "returns the current line number" do
@@ -37,7 +56,26 @@ describe "IO#lineno=" do
   end
 
   it "raises an IOError on a closed stream" do
-    -> { IOSpecs.closed_io.lineno = 5 }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.lineno = 5 }.should.raise(IOError)
+  end
+
+  it "raises an IOError on a write-only stream" do
+    name = tmp("io_lineno.txt")
+    begin
+      File.open(name, 'w') do |f|
+        -> { f.lineno = 0 }.should.raise(IOError)
+      end
+    ensure
+      rm_r name
+    end
+  end
+
+  it "raises an IOError on a duplexed stream with the read side closed" do
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    IO.popen(cmd, 'r+') do |p|
+      p.close_read
+      -> { p.lineno = 0 }.should.raise(IOError)
+    end
   end
 
   it "calls #to_int on a non-numeric argument" do
@@ -56,8 +94,13 @@ describe "IO#lineno=" do
     @io.lineno.should == 92233
   end
 
-  it "raises TypeError on nil argument" do
-    -> { @io.lineno = nil }.should raise_error(TypeError)
+  it "raises TypeError if cannot convert argument to Integer implicitly" do
+    -> { @io.lineno = "1" }.should.raise(TypeError, 'no implicit conversion of String into Integer')
+    -> { @io.lineno = nil }.should raise_consistent_error(TypeError, 'no implicit conversion of nil into Integer')
+  end
+
+  it "does not accept Integers that don't fit in a C int" do
+    -> { @io.lineno = 2**32 }.should.raise(RangeError)
   end
 
   it "sets the current line number to the given value" do
diff --git a/spec/ruby/core/io/lines_spec.rb b/spec/ruby/core/io/lines_spec.rb
deleted file mode 100644
index a8b8023a2a..0000000000
--- a/spec/ruby/core/io/lines_spec.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-# -*- encoding: utf-8 -*-
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-
-describe "IO#lines" do
-  before :each do
-    @io = IOSpecs.io_fixture "lines.txt"
-  end
-
-  after :each do
-    @io.close if @io
-  end
-
-  it "returns an Enumerator" do
-    @io.lines.should be_an_instance_of(Enumerator)
-  end
-
-  describe "when no block is given" do
-    it "returns an Enumerator" do
-      @io.lines.should be_an_instance_of(Enumerator)
-    end
-
-    describe "returned Enumerator" do
-      describe "size" do
-        it "should return nil" do
-          @io.lines.size.should == nil
-        end
-      end
-    end
-  end
-
-  it "returns a line when accessed" do
-    enum = @io.lines
-    enum.first.should == IOSpecs.lines[0]
-  end
-
-  it "yields each line to the passed block" do
-    ScratchPad.record []
-    @io.lines { |s| ScratchPad << s }
-    ScratchPad.recorded.should == IOSpecs.lines
-  end
-end
diff --git a/spec/ruby/core/io/new_spec.rb b/spec/ruby/core/io/new_spec.rb
index 3597098caf..979ac0efcb 100644
--- a/spec/ruby/core/io/new_spec.rb
+++ b/spec/ruby/core/io/new_spec.rb
@@ -1,8 +1,16 @@
 require_relative '../../spec_helper'
 require_relative 'shared/new'
 
+# NOTE: should be synchronized with library/stringio/initialize_spec.rb
+
 describe "IO.new" do
   it_behaves_like :io_new, :new
+
+  it "does not use the given block and warns to use IO::open" do
+    -> {
+      @io = IO.send(@method, @fd) { raise }
+    }.should complain(/warning: IO::new\(\) does not take block; use IO::open\(\) instead/)
+  end
 end
 
 describe "IO.new" do
diff --git a/spec/ruby/core/io/nonblock_spec.rb b/spec/ruby/core/io/nonblock_spec.rb
new file mode 100644
index 0000000000..99dc0cafd0
--- /dev/null
+++ b/spec/ruby/core/io/nonblock_spec.rb
@@ -0,0 +1,48 @@
+require_relative '../../spec_helper'
+
+platform_is_not :windows do
+  describe "IO#nonblock?" do
+    before :all do
+      require 'io/nonblock'
+    end
+
+    it "returns false for a file by default" do
+      File.open(__FILE__) do |f|
+        f.nonblock?.should == false
+      end
+    end
+
+    it "returns true for pipe by default" do
+      r, w = IO.pipe
+      begin
+        r.nonblock?.should == true
+        w.nonblock?.should == true
+      ensure
+        r.close
+        w.close
+      end
+    end
+
+    it "returns true for socket by default" do
+      require 'socket'
+      TCPServer.open(0) do |socket|
+        socket.nonblock?.should == true
+      end
+    end
+  end
+
+  describe "IO#nonblock=" do
+    before :all do
+      require 'io/nonblock'
+    end
+
+    it "changes the IO to non-blocking mode" do
+      File.open(__FILE__) do |f|
+        f.nonblock = true
+        f.nonblock?.should == true
+        f.nonblock = false
+        f.nonblock?.should == false
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/io/open_spec.rb b/spec/ruby/core/io/open_spec.rb
index 94df5a5ef6..ff22d14685 100644
--- a/spec/ruby/core/io/open_spec.rb
+++ b/spec/ruby/core/io/open_spec.rb
@@ -32,11 +32,24 @@ describe "IO.open" do
         super()
         ScratchPad.record :called
       end
-      io.closed?.should be_false
+      io.closed?.should == false
     end
     ScratchPad.recorded.should == :called
   end
 
+  it "propagate an exception in the block after calling #close" do
+    -> do
+      IO.open(@fd, "w") do |io|
+        IOSpecs.io_mock(io, :close) do
+          super()
+          ScratchPad.record :called
+        end
+        raise Exception
+      end
+    end.should.raise(Exception)
+    ScratchPad.recorded.should == :called
+  end
+
   it "propagates an exception raised by #close that is not a StandardError" do
     -> do
       IO.open(@fd, "w") do |io|
@@ -46,7 +59,7 @@ describe "IO.open" do
           raise Exception
         end
       end
-    end.should raise_error(Exception)
+    end.should.raise(Exception)
     ScratchPad.recorded.should == :called
   end
 
@@ -59,11 +72,11 @@ describe "IO.open" do
           raise StandardError
         end
       end
-    end.should raise_error(StandardError)
+    end.should.raise(StandardError)
     ScratchPad.recorded.should == :called
   end
 
-  it "does not propagate a IOError with 'closed stream' message raised by #close" do
+  it "does not propagate an IOError with 'closed stream' message raised by #close" do
     IO.open(@fd, "w") do |io|
       IOSpecs.io_mock(io, :close) do
         super()
@@ -74,7 +87,7 @@ describe "IO.open" do
     ScratchPad.recorded.should == :called
   end
 
-  it "does not set last error when a IOError with 'closed stream' raised by #close" do
+  it "does not set last error when an IOError with 'closed stream' raised by #close" do
     IO.open(@fd, "w") do |io|
       IOSpecs.io_mock(io, :close) do
         super()
diff --git a/spec/ruby/core/io/output_spec.rb b/spec/ruby/core/io/output_spec.rb
index 2aafb305f4..0decf8c95b 100644
--- a/spec/ruby/core/io/output_spec.rb
+++ b/spec/ruby/core/io/output_spec.rb
@@ -16,7 +16,7 @@ describe "IO#<<" do
 
   it "raises an error if the stream is closed" do
     io = IOSpecs.closed_io
-    -> { io << "test" }.should raise_error(IOError)
+    -> { io << "test" }.should.raise(IOError)
   end
 
   it "returns self" do
diff --git a/spec/ruby/core/io/path_spec.rb b/spec/ruby/core/io/path_spec.rb
new file mode 100644
index 0000000000..798adb2163
--- /dev/null
+++ b/spec/ruby/core/io/path_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+
+describe "IO#path" do
+  it "returns the path of the file associated with the IO object" do
+    path = tmp("io_path.txt")
+    File.open(path, "w") do |file|
+      IO.new(file.fileno, path: file.path, autoclose: false).path.should == file.path
+    end
+  ensure
+    File.unlink(path)
+  end
+end
diff --git a/spec/ruby/core/io/pid_spec.rb b/spec/ruby/core/io/pid_spec.rb
index bc09fe7c3b..04956887ff 100644
--- a/spec/ruby/core/io/pid_spec.rb
+++ b/spec/ruby/core/io/pid_spec.rb
@@ -25,11 +25,11 @@ describe "IO#pid" do
   end
 
   it "returns the ID of a process associated with stream" do
-    @io.pid.should_not be_nil
+    @io.pid.should_not == nil
   end
 
   it "raises an IOError on closed stream" do
     @io.close
-    -> { @io.pid }.should raise_error(IOError)
+    -> { @io.pid }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/pipe_spec.rb b/spec/ruby/core/io/pipe_spec.rb
index a7dcb7fab8..9f1b01a5cd 100644
--- a/spec/ruby/core/io/pipe_spec.rb
+++ b/spec/ruby/core/io/pipe_spec.rb
@@ -16,14 +16,25 @@ describe "IO.pipe" do
 
   it "returns two IO objects" do
     @r, @w = IO.pipe
-    @r.should be_kind_of(IO)
-    @w.should be_kind_of(IO)
+    @r.should.is_a?(IO)
+    @w.should.is_a?(IO)
   end
 
   it "returns instances of a subclass when called on a subclass" do
     @r, @w = IOSpecs::SubIO.pipe
-    @r.should be_an_instance_of(IOSpecs::SubIO)
-    @w.should be_an_instance_of(IOSpecs::SubIO)
+    @r.should.instance_of?(IOSpecs::SubIO)
+    @w.should.instance_of?(IOSpecs::SubIO)
+  end
+
+  it "does not use IO.new method to create pipes and allows its overriding" do
+    ScratchPad.record []
+
+    # so redefined .new is not called, but original #initialize is
+    @r, @w = IOSpecs::SubIOWithRedefinedNew.pipe
+    ScratchPad.recorded.should == [:call_original_initialize, :call_original_initialize] # called 2 times - for each pipe (r and w)
+
+    @r.should.instance_of?(IOSpecs::SubIOWithRedefinedNew)
+    @w.should.instance_of?(IOSpecs::SubIOWithRedefinedNew)
   end
 end
 
@@ -31,8 +42,8 @@ describe "IO.pipe" do
   describe "passed a block" do
     it "yields two IO objects" do
       IO.pipe do |r, w|
-        r.should be_kind_of(IO)
-        w.should be_kind_of(IO)
+        r.should.is_a?(IO)
+        w.should.is_a?(IO)
       end
     end
 
@@ -44,8 +55,8 @@ describe "IO.pipe" do
       r, w = IO.pipe do |_r, _w|
         [_r, _w]
       end
-      r.closed?.should == true
-      w.closed?.should == true
+      r.should.closed?
+      w.should.closed?
     end
 
     it "closes both IO objects when the block raises" do
@@ -56,9 +67,9 @@ describe "IO.pipe" do
           w = _w
           raise RuntimeError
         end
-      end.should raise_error(RuntimeError)
-      r.closed?.should == true
-      w.closed?.should == true
+      end.should.raise(RuntimeError)
+      r.should.closed?
+      w.should.closed?
     end
 
     it "allows IO objects to be closed within the block" do
@@ -67,8 +78,8 @@ describe "IO.pipe" do
         _w.close
         [_r, _w]
       end
-      r.closed?.should == true
-      w.closed?.should == true
+      r.should.closed?
+      w.should.closed?
     end
   end
 end
@@ -89,7 +100,7 @@ describe "IO.pipe" do
 
     IO.pipe do |r, w|
       r.external_encoding.should == Encoding::ISO_8859_1
-      r.internal_encoding.should be_nil
+      r.internal_encoding.should == nil
     end
   end
 
@@ -109,14 +120,14 @@ describe "IO.pipe" do
 
     IO.pipe do |r, w|
       r.external_encoding.should == Encoding::UTF_8
-      r.internal_encoding.should be_nil
+      r.internal_encoding.should == nil
     end
   end
 
   it "sets the external encoding of the read end when passed an Encoding argument" do
     IO.pipe(Encoding::UTF_8) do |r, w|
       r.external_encoding.should == Encoding::UTF_8
-      r.internal_encoding.should be_nil
+      r.internal_encoding.should == nil
     end
   end
 
@@ -130,14 +141,14 @@ describe "IO.pipe" do
   it "sets the external encoding of the read end when passed the name of an Encoding" do
     IO.pipe("UTF-8") do |r, w|
       r.external_encoding.should == Encoding::UTF_8
-      r.internal_encoding.should be_nil
+      r.internal_encoding.should == nil
     end
   end
 
   it "accepts 'bom|' prefix for external encoding" do
     IO.pipe("BOM|UTF-8") do |r, w|
       r.external_encoding.should == Encoding::UTF_8
-      r.internal_encoding.should be_nil
+      r.internal_encoding.should == nil
     end
   end
 
@@ -202,13 +213,13 @@ describe "IO.pipe" do
 
   it "sets no external encoding for the write end" do
     IO.pipe(Encoding::UTF_8) do |r, w|
-      w.external_encoding.should be_nil
+      w.external_encoding.should == nil
     end
   end
 
   it "sets no internal encoding for the write end" do
     IO.pipe(Encoding::UTF_8) do |r, w|
-      w.external_encoding.should be_nil
+      w.external_encoding.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/io/popen_spec.rb b/spec/ruby/core/io/popen_spec.rb
index 622b3a9394..b5747bf255 100644
--- a/spec/ruby/core/io/popen_spec.rb
+++ b/spec/ruby/core/io/popen_spec.rb
@@ -1,42 +1,39 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../process/fixtures/common'
 
 describe "IO.popen" do
+  ProcessSpecs.use_system_ruby(self)
+
   before :each do
+    @fname = tmp("IO_popen_spec")
     @io = nil
+    @var = "$FOO"
+    platform_is :windows do
+      @var = "%FOO%"
+    end
   end
 
   after :each do
-    @io.close if @io
+    @io.close if @io and !@io.closed?
+    rm_r @fname
   end
 
   it "returns an open IO" do
     @io = IO.popen(ruby_cmd('exit'), "r")
-    @io.closed?.should be_false
+    @io.closed?.should == false
   end
 
   it "reads a read-only pipe" do
-    @io = IO.popen(ruby_cmd('puts "foo"'), "r")
+    @io = IO.popen('echo foo', "r")
     @io.read.should == "foo\n"
   end
 
   it "raises IOError when writing a read-only pipe" do
-    @io = IO.popen(ruby_cmd('puts "foo"'), "r")
-    -> { @io.write('bar') }.should raise_error(IOError)
+    @io = IO.popen('echo foo', "r")
+    -> { @io.write('bar') }.should.raise(IOError)
     @io.read.should == "foo\n"
   end
-end
-
-describe "IO.popen" do
-  before :each do
-    @fname = tmp("IO_popen_spec")
-    @io = nil
-  end
-
-  after :each do
-    @io.close if @io and !@io.closed?
-    rm_r @fname
-  end
 
   it "sees an infinitely looping subprocess exit when read pipe is closed" do
     io = IO.popen ruby_cmd('r = loop{puts "y"; 0} rescue 1; exit r'), 'r'
@@ -55,7 +52,7 @@ describe "IO.popen" do
 
   it "raises IOError when reading a write-only pipe" do
     @io = IO.popen(ruby_cmd('IO.copy_stream(STDIN,STDOUT)'), "w")
-    -> { @io.read }.should raise_error(IOError)
+    -> { @io.read }.should.raise(IOError)
   end
 
   it "reads and writes a read/write pipe" do
@@ -80,16 +77,16 @@ describe "IO.popen" do
     Process.kill "KILL", pid
     @io.close
     platform_is_not :windows do
-      $?.signaled?.should == true
+      $?.should.signaled?
     end
     platform_is :windows do
-      $?.exited?.should == true
+      $?.should.exited?
     end
   end
 
   it "returns an instance of a subclass when called on a subclass" do
     @io = IOSpecs::SubIO.popen(ruby_cmd('exit'), "r")
-    @io.should be_an_instance_of(IOSpecs::SubIO)
+    @io.should.instance_of?(IOSpecs::SubIO)
   end
 
   it "coerces mode argument with #to_str" do
@@ -97,38 +94,44 @@ describe "IO.popen" do
     mode.should_receive(:to_str).and_return("r")
     @io = IO.popen(ruby_cmd('exit 0'), mode)
   end
-end
 
-describe "IO.popen" do
-  before :each do
-    @io = nil
+  it "accepts a path using the chdir: keyword argument" do
+    path = File.dirname(@fname)
+
+    @io = IO.popen(ruby_cmd("puts Dir.pwd"), "r", chdir: path)
+    @io.read.chomp.should == path
   end
 
-  after :each do
-    @io.close if @io
+  it "accepts a path using the chdir: keyword argument and a coercible path" do
+    path = File.dirname(@fname)
+    object = mock("path")
+    object.should_receive(:to_path).and_return(path)
+
+    @io = IO.popen(ruby_cmd("puts Dir.pwd"), "r", chdir: object)
+    @io.read.chomp.should == path
   end
 
   describe "with a block" do
     it "yields an open IO to the block" do
       IO.popen(ruby_cmd('exit'), "r") do |io|
-        io.closed?.should be_false
+        io.closed?.should == false
       end
     end
 
     it "yields an instance of a subclass when called on a subclass" do
       IOSpecs::SubIO.popen(ruby_cmd('exit'), "r") do |io|
-        io.should be_an_instance_of(IOSpecs::SubIO)
+        io.should.instance_of?(IOSpecs::SubIO)
       end
     end
 
     it "closes the IO after yielding" do
       io = IO.popen(ruby_cmd('exit'), "r") { |_io| _io }
-      io.closed?.should be_true
+      io.closed?.should == true
     end
 
     it "allows the IO to be closed inside the block" do
       io = IO.popen(ruby_cmd('exit'), 'r') { |_io| _io.close; _io }
-      io.closed?.should be_true
+      io.closed?.should == true
     end
 
     it "returns the value of the block" do
@@ -166,18 +169,18 @@ describe "IO.popen" do
   it "sets the internal encoding to nil if it's the same as the external encoding" do
     @io = IO.popen(ruby_cmd('exit'), external_encoding: Encoding::EUC_JP,
                           internal_encoding: Encoding::EUC_JP)
-    @io.internal_encoding.should be_nil
+    @io.internal_encoding.should == nil
   end
 
   context "with a leading ENV Hash" do
     it "accepts a single String command" do
-      IO.popen({"FOO" => "bar"}, ruby_cmd('puts ENV["FOO"]')) do |io|
+      IO.popen({"FOO" => "bar"}, "echo #{@var}") do |io|
         io.read.should == "bar\n"
       end
     end
 
     it "accepts a single String command, and an IO mode" do
-      IO.popen({"FOO" => "bar"}, ruby_cmd('puts ENV["FOO"]'), "r") do |io|
+      IO.popen({"FOO" => "bar"}, "echo #{@var}", "r") do |io|
         io.read.should == "bar\n"
       end
     end
diff --git a/spec/ruby/core/io/pread_spec.rb b/spec/ruby/core/io/pread_spec.rb
index bfe6472fef..cfb8dc4c68 100644
--- a/spec/ruby/core/io/pread_spec.rb
+++ b/spec/ruby/core/io/pread_spec.rb
@@ -1,52 +1,138 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  platform_is_not :windows do
-    describe "IO#pread" do
-      before :each do
-        @fname = tmp("io_pread.txt")
-        @contents = "1234567890"
-        touch(@fname) { |f| f.write @contents }
-        @file = File.open(@fname, "r+")
-      end
-
-      after :each do
-        @file.close
-        rm_r @fname
-      end
-
-      it "accepts a length, and an offset" do
-        @file.pread(4, 0).should == "1234"
-        @file.pread(3, 4).should == "567"
-      end
-
-      it "accepts a length, an offset, and an output buffer" do
-        buffer = "foo"
-        @file.pread(3, 4, buffer)
-        buffer.should == "567"
-      end
-
-      it "does not advance the file pointer" do
-        @file.pread(4, 0).should == "1234"
-        @file.read.should == "1234567890"
-      end
-
-      it "raises EOFError if end-of-file is reached" do
-        -> { @file.pread(1, 10) }.should raise_error(EOFError)
-      end
-
-      it "raises IOError when file is not open in read mode" do
-        File.open(@fname, "w") do |file|
-          -> { file.pread(1, 1) }.should raise_error(IOError)
-        end
-      end
-
-      it "raises IOError when file is closed" do
-        file = File.open(@fname, "r+")
-        file.close
-        -> { file.pread(1, 1) }.should raise_error(IOError)
-      end
+describe "IO#pread" do
+  before :each do
+    @fname = tmp("io_pread.txt")
+    @contents = "1234567890"
+    touch(@fname) { |f| f.write @contents }
+    @file = File.open(@fname, "r+")
+  end
+
+  after :each do
+    @file.close
+    rm_r @fname
+  end
+
+  it "accepts a length, and an offset" do
+    @file.pread(4, 0).should == "1234"
+    @file.pread(3, 4).should == "567"
+  end
+
+  it "accepts a length, an offset, and an output buffer" do
+    buffer = +"foo"
+    @file.pread(3, 4, buffer).should.equal?(buffer)
+    buffer.should == "567"
+  end
+
+  it "shrinks the buffer in case of less bytes read" do
+    buffer = +"foo"
+    @file.pread(1, 0, buffer)
+    buffer.should == "1"
+  end
+
+  it "grows the buffer in case of more bytes read" do
+    buffer = +"foo"
+    @file.pread(5, 0, buffer)
+    buffer.should == "12345"
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @file.pread(10, 0, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
+  end
+
+  it "does not advance the file pointer" do
+    @file.pread(4, 0).should == "1234"
+    @file.read.should == "1234567890"
+  end
+
+  it "ignores the current offset" do
+    @file.pos = 3
+    @file.pread(4, 0).should == "1234"
+  end
+
+  it "returns an empty string for maxlen = 0" do
+    @file.pread(0, 4).should == ""
+  end
+
+  it "returns a buffer for maxlen = 0 when buffer specified" do
+    buffer = +"foo"
+    @file.pread(0, 4, buffer).should.equal?(buffer)
+    buffer.should == "foo"
+  end
+
+  it "ignores the offset for maxlen = 0, even if it is out of file bounds" do
+    @file.pread(0, 400).should == ""
+  end
+
+  it "does not reset the buffer when reading with maxlen = 0" do
+    buffer = +"foo"
+    @file.pread(0, 4, buffer)
+    buffer.should == "foo"
+
+    @file.pread(0, 400, buffer)
+    buffer.should == "foo"
+  end
+
+  it "converts maxlen to Integer using #to_int" do
+    maxlen = mock('maxlen')
+    maxlen.should_receive(:to_int).and_return(4)
+    @file.pread(maxlen, 0).should == "1234"
+  end
+
+  it "converts offset to Integer using #to_int" do
+    offset = mock('offset')
+    offset.should_receive(:to_int).and_return(0)
+    @file.pread(4, offset).should == "1234"
+  end
+
+  it "converts a buffer to String using to_str" do
+    buffer = mock('buffer')
+    buffer.should_receive(:to_str).at_least(1).and_return(+"foo")
+    @file.pread(4, 0, buffer)
+    buffer.should_not.is_a?(String)
+    buffer.to_str.should == "1234"
+  end
+
+  it "raises TypeError if maxlen is not an Integer and cannot be coerced into Integer" do
+    maxlen = Object.new
+    -> { @file.pread(maxlen, 0) }.should.raise(TypeError, 'no implicit conversion of Object into Integer')
+  end
+
+  it "raises TypeError if offset is not an Integer and cannot be coerced into Integer" do
+    offset = Object.new
+    -> { @file.pread(4, offset) }.should.raise(TypeError, 'no implicit conversion of Object into Integer')
+  end
+
+  it "raises ArgumentError for negative values of maxlen" do
+    -> { @file.pread(-4, 0) }.should.raise(ArgumentError, 'negative string size (or size too big)')
+  end
+
+  it "raised Errno::EINVAL for negative values of offset" do
+    -> { @file.pread(4, -1) }.should.raise(Errno::EINVAL, /Invalid argument/)
+  end
+
+  it "raises TypeError if the buffer is not a String and cannot be coerced into String" do
+    buffer = Object.new
+    -> { @file.pread(4, 0, buffer) }.should.raise(TypeError, 'no implicit conversion of Object into String')
+  end
+
+  it "raises EOFError if end-of-file is reached" do
+    -> { @file.pread(1, 10) }.should.raise(EOFError)
+  end
+
+  it "raises IOError when file is not open in read mode" do
+    File.open(@fname, "w") do |file|
+      -> { file.pread(1, 1) }.should.raise(IOError)
     end
   end
+
+  it "raises IOError when file is closed" do
+    file = File.open(@fname, "r+")
+    file.close
+    -> { file.pread(1, 1) }.should.raise(IOError)
+  end
 end
diff --git a/spec/ruby/core/io/print_spec.rb b/spec/ruby/core/io/print_spec.rb
index 2021cd5420..065cb3b8cb 100644
--- a/spec/ruby/core/io/print_spec.rb
+++ b/spec/ruby/core/io/print_spec.rb
@@ -1,18 +1,29 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe IO, "#print" do
+describe "IO#print" do
   before :each do
-    @old_separator = $\
-    $\ = '->'
+    @old_record_separator = $\
+    @old_field_separator = $,
+    suppress_warning {
+      $\ = '->'
+      $, = '^^'
+    }
     @name = tmp("io_print")
   end
 
   after :each do
-    $\ = @old_separator
+    suppress_warning {
+      $\ = @old_record_separator
+      $, = @old_field_separator
+    }
     rm_r @name
   end
 
+  it "returns nil" do
+    touch(@name) { |f| f.print.should == nil }
+  end
+
   it "writes $_.to_s followed by $\\ (if any) to the stream if no arguments given" do
     o = mock('o')
     o.should_receive(:to_s).and_return("mockmockmock")
@@ -38,16 +49,18 @@ describe IO, "#print" do
     IO.read(@name).should == "hello#{$\}"
   end
 
-  it "writes each obj.to_s to the stream and appends $\\ (if any) given multiple objects" do
+  it "writes each obj.to_s to the stream separated by $, (if any) and appends $\\ (if any) given multiple objects" do
     o, o2 = Object.new, Object.new
     def o.to_s(); 'o'; end
     def o2.to_s(); 'o2'; end
 
-    touch(@name) { |f| f.print(o, o2) }
-    IO.read(@name).should == "#{o.to_s}#{o2.to_s}#{$\}"
+    suppress_warning {
+      touch(@name) { |f| f.print(o, o2) }
+    }
+    IO.read(@name).should == "#{o.to_s}#{$,}#{o2.to_s}#{$\}"
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.print("stuff") }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.print("stuff") }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/printf_spec.rb b/spec/ruby/core/io/printf_spec.rb
index baa00f14ce..d5519bdaa3 100644
--- a/spec/ruby/core/io/printf_spec.rb
+++ b/spec/ruby/core/io/printf_spec.rb
@@ -27,6 +27,6 @@ describe "IO#printf" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.printf("stuff") }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.printf("stuff") }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/puts_spec.rb b/spec/ruby/core/io/puts_spec.rb
index 3e4b877b7f..df526ea56a 100644
--- a/spec/ruby/core/io/puts_spec.rb
+++ b/spec/ruby/core/io/puts_spec.rb
@@ -6,7 +6,7 @@ describe "IO#puts" do
     @before_separator = $/
     @name = tmp("io_puts.txt")
     @io = new_io @name
-    ScratchPad.record ""
+    ScratchPad.record(+"")
     def @io.write(str)
       ScratchPad << str
     end
@@ -16,7 +16,7 @@ describe "IO#puts" do
     ScratchPad.clear
     @io.close if @io
     rm_r @name
-    $/ = @before_separator
+    suppress_warning {$/ = @before_separator}
   end
 
   it "writes just a newline when given no args" do
@@ -25,7 +25,7 @@ describe "IO#puts" do
   end
 
   it "writes just a newline when given just a newline" do
-    -> { $stdout.puts "\n" }.should output_to_fd("\n", STDOUT)
+    -> { $stdout.puts "\n" }.should output_to_fd("\n", $stdout)
   end
 
   it "writes empty string with a newline when given nil as an arg" do
@@ -33,7 +33,7 @@ describe "IO#puts" do
     ScratchPad.recorded.should == "\n"
   end
 
-  it "writes empty string with a newline when when given nil as multiple args" do
+  it "writes empty string with a newline when given nil as multiple args" do
     @io.puts(nil, nil).should == nil
     ScratchPad.recorded.should == "\n\n"
   end
@@ -105,13 +105,13 @@ describe "IO#puts" do
   end
 
   it "ignores the $/ separator global" do
-    $/ = ":"
+    suppress_warning {$/ = ":"}
     @io.puts(5).should == nil
     ScratchPad.recorded.should == "5\n"
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.puts("stuff") }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.puts("stuff") }.should.raise(IOError)
   end
 
   it "writes crlf when IO is opened with newline: :crlf" do
diff --git a/spec/ruby/core/io/pwrite_spec.rb b/spec/ruby/core/io/pwrite_spec.rb
index 929ed08698..c318d551bc 100644
--- a/spec/ruby/core/io/pwrite_spec.rb
+++ b/spec/ruby/core/io/pwrite_spec.rb
@@ -1,45 +1,67 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  platform_is_not :windows do
-    describe "IO#pwrite" do
-      before :each do
-        @fname = tmp("io_pwrite.txt")
-        @file = File.open(@fname, "w+")
-      end
-
-      after :each do
-        @file.close
-        rm_r @fname
-      end
-
-      it "returns the number of bytes written" do
-        @file.pwrite("foo", 0).should == 3
-      end
-
-      it "accepts a string and an offset"  do
-        @file.pwrite("foo", 2)
-        @file.pread(3, 2).should == "foo"
-      end
-
-      it "does not advance the pointer in the file" do
-        @file.pwrite("bar", 3)
-        @file.write("foo")
-        @file.pread(6, 0).should == "foobar"
-      end
-
-      it "raises IOError when file is not open in write mode" do
-        File.open(@fname, "r") do |file|
-          -> { file.pwrite("foo", 1) }.should raise_error(IOError)
-        end
-      end
-
-      it "raises IOError when file is closed" do
-        file = File.open(@fname, "w+")
-        file.close
-        -> { file.pwrite("foo", 1) }.should raise_error(IOError)
-      end
+describe "IO#pwrite" do
+  before :each do
+    @fname = tmp("io_pwrite.txt")
+    @file = File.open(@fname, "w+")
+  end
+
+  after :each do
+    @file.close
+    rm_r @fname
+  end
+
+  it "returns the number of bytes written" do
+    @file.pwrite("foo", 0).should == 3
+  end
+
+  it "accepts a string and an offset"  do
+    @file.pwrite("foo", 2)
+    @file.pread(3, 2).should == "foo"
+  end
+
+  it "does not advance the pointer in the file" do
+    @file.pwrite("bar", 3)
+    @file.write("foo")
+    @file.pread(6, 0).should == "foobar"
+  end
+
+  it "calls #to_s on the object to be written" do
+    object = mock("to_s")
+    object.should_receive(:to_s).and_return("foo")
+    @file.pwrite(object, 0)
+    @file.pread(3, 0).should == "foo"
+  end
+
+  it "calls #to_int on the offset" do
+    offset = mock("to_int")
+    offset.should_receive(:to_int).and_return(2)
+    @file.pwrite("foo", offset)
+    @file.pread(3, 2).should == "foo"
+  end
+
+  it "raises IOError when file is not open in write mode" do
+    File.open(@fname, "r") do |file|
+      -> { file.pwrite("foo", 1) }.should.raise(IOError, "not opened for writing")
     end
   end
+
+  it "raises IOError when file is closed" do
+    file = File.open(@fname, "w+")
+    file.close
+    -> { file.pwrite("foo", 1) }.should.raise(IOError, "closed stream")
+  end
+
+  it "raises a NoMethodError if object does not respond to #to_s" do
+    -> {
+      @file.pwrite(BasicObject.new, 0)
+    }.should.raise(NoMethodError, /undefined method [`']to_s'/)
+  end
+
+  it "raises a TypeError if the offset cannot be converted to an Integer" do
+    -> {
+      @file.pwrite("foo", Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+  end
 end
diff --git a/spec/ruby/core/io/read_nonblock_spec.rb b/spec/ruby/core/io/read_nonblock_spec.rb
index 63ccab5a44..511cf03263 100644
--- a/spec/ruby/core/io/read_nonblock_spec.rb
+++ b/spec/ruby/core/io/read_nonblock_spec.rb
@@ -12,12 +12,12 @@ describe "IO#read_nonblock" do
   end
 
   it "raises an exception extending IO::WaitReadable when there is no data" do
-    -> { @read.read_nonblock(5) }.should raise_error(IO::WaitReadable) { |e|
+    -> { @read.read_nonblock(5) }.should.raise(IO::WaitReadable) { |e|
       platform_is_not :windows do
-        e.should be_kind_of(Errno::EAGAIN)
+        e.should.is_a?(Errno::EAGAIN)
       end
       platform_is :windows do
-        e.should be_kind_of(Errno::EWOULDBLOCK)
+        e.should.is_a?(Errno::EWOULDBLOCK)
       end
     }
   end
@@ -36,7 +36,7 @@ describe "IO#read_nonblock" do
 
         @read.read_nonblock(5)
 
-        @read.read_nonblock(5, exception: false).should be_nil
+        @read.read_nonblock(5, exception: false).should == nil
       end
     end
   end
@@ -46,7 +46,7 @@ describe "IO#read_nonblock" do
       require 'io/nonblock'
       @write.write "abc"
       @read.read_nonblock(1).should == "a"
-      @read.nonblock?.should == true
+      @read.should.nonblock?
     end
   end
 
@@ -55,6 +55,27 @@ describe "IO#read_nonblock" do
     @read.read_nonblock(4).should == "hell"
   end
 
+  it "reads after ungetc with data in the buffer" do
+    @write.write("foobar")
+    @read.set_encoding(
+      'utf-8', universal_newline: false
+    )
+    c = @read.getc
+    @read.ungetc(c)
+    @read.read_nonblock(3).should == "foo"
+    @read.read_nonblock(3).should == "bar"
+  end
+
+  it "raises an exception after ungetc with data in the buffer and character conversion enabled" do
+    @write.write("foobar")
+    @read.set_encoding(
+      'utf-8', universal_newline: true
+    )
+    c = @read.getc
+    @read.ungetc(c)
+    -> { @read.read_nonblock(3).should == "foo" }.should.raise(IOError)
+  end
+
   it "returns less data if that is all that is available" do
     @write << "hello"
     @read.read_nonblock(10).should == "hello"
@@ -70,22 +91,41 @@ describe "IO#read_nonblock" do
     @read.read_nonblock(1).should == "1"
   end
 
+  it "raises ArgumentError when length is less than 0" do
+    -> { @read.read_nonblock(-1) }.should.raise(ArgumentError)
+  end
+
   it "reads into the passed buffer" do
-    buffer = ""
+    buffer = +""
     @write.write("1")
     @read.read_nonblock(1, buffer)
     buffer.should == "1"
   end
 
   it "returns the passed buffer" do
-    buffer = ""
+    buffer = +""
     @write.write("1")
     output = @read.read_nonblock(1, buffer)
-    output.should equal(buffer)
+    output.should.equal?(buffer)
+  end
+
+  it "discards the existing buffer content upon successful read" do
+    buffer = +"existing content"
+    @write.write("hello world")
+    @write.close
+    @read.read_nonblock(11, buffer)
+    buffer.should == "hello world"
+  end
+
+  it "discards the existing buffer content upon error" do
+    buffer = +"existing content"
+    @write.close
+    -> { @read.read_nonblock(1, buffer) }.should.raise(EOFError)
+    buffer.should.empty?
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.read_nonblock(5) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.read_nonblock(5) }.should.raise(IOError)
   end
 
   it "raises EOFError when the end is reached" do
@@ -94,6 +134,15 @@ describe "IO#read_nonblock" do
 
     @read.read_nonblock(5)
 
-    -> { @read.read_nonblock(5) }.should raise_error(EOFError)
+    -> { @read.read_nonblock(5) }.should.raise(EOFError)
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @write.write("abc")
+    @write.close
+    @read.read_nonblock(10, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
   end
 end
diff --git a/spec/ruby/core/io/read_spec.rb b/spec/ruby/core/io/read_spec.rb
index 1e9a8d2a4f..dd787c9b60 100644
--- a/spec/ruby/core/io/read_spec.rb
+++ b/spec/ruby/core/io/read_spec.rb
@@ -23,6 +23,15 @@ describe "IO.read" do
     IO.read(p)
   end
 
+  # https://bugs.ruby-lang.org/issues/19354
+  it "accepts options as keyword arguments" do
+    IO.read(@fname, 3, 0, mode: "r+").should == @contents[0, 3]
+
+    -> {
+      IO.read(@fname, 3, 0, {mode: "r+"})
+    }.should.raise(ArgumentError, /wrong number of arguments/)
+  end
+
   it "accepts an empty options Hash" do
     IO.read(@fname, **{}).should == @contents
   end
@@ -36,11 +45,11 @@ describe "IO.read" do
   end
 
   it "raises an IOError if the options Hash specifies write mode" do
-    -> { IO.read(@fname, 3, 0, mode: "w") }.should raise_error(IOError)
+    -> { IO.read(@fname, 3, 0, mode: "w") }.should.raise(IOError)
   end
 
   it "raises an IOError if the options Hash specifies append only mode" do
-    -> { IO.read(@fname, mode: "a") }.should raise_error(IOError)
+    -> { IO.read(@fname, mode: "a") }.should.raise(IOError)
   end
 
   it "reads the file if the options Hash includes read mode" do
@@ -55,6 +64,24 @@ describe "IO.read" do
     IO.read(@fname, mode: "a+").should == @contents
   end
 
+  platform_is_not :windows do
+  end
+
+  it "disregards other options if :open_args is given" do
+    string = IO.read(@fname,mode: "w", encoding: Encoding::UTF_32LE, open_args: ["r", encoding: Encoding::UTF_8])
+    string.encoding.should == Encoding::UTF_8
+  end
+
+  it "doesn't require mode to be specified in :open_args" do
+    string = IO.read(@fname, nil, 0, open_args: [{encoding: Encoding::US_ASCII}])
+    string.encoding.should == Encoding::US_ASCII
+  end
+
+  it "doesn't require mode to be specified in :open_args even if flags option passed" do
+    string = IO.read(@fname, nil, 0, open_args: [{encoding: Encoding::US_ASCII, flags: File::CREAT}])
+    string.encoding.should == Encoding::US_ASCII
+  end
+
   it "treats second nil argument as no length limit" do
     IO.read(@fname, nil).should == @contents
     IO.read(@fname, nil, 5).should == IO.read(@fname, @contents.length, 5)
@@ -77,22 +104,31 @@ describe "IO.read" do
     IO.read(@fname, 1, 10).should == nil
   end
 
+  it "returns an empty string when reading zero bytes" do
+    IO.read(@fname, 0).should == ''
+  end
+
+  it "returns a String in BINARY when passed a size" do
+    IO.read(@fname, 1).encoding.should == Encoding::BINARY
+    IO.read(@fname, 0).encoding.should == Encoding::BINARY
+  end
+
   it "raises an Errno::ENOENT when the requested file does not exist" do
     rm_r @fname
-    -> { IO.read @fname }.should raise_error(Errno::ENOENT)
+    -> { IO.read @fname }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when not passed a String type" do
-    -> { IO.read nil }.should raise_error(TypeError)
+    -> { IO.read nil }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when not passed a valid length" do
-    -> { IO.read @fname, -1 }.should raise_error(ArgumentError)
+    -> { IO.read @fname, -1 }.should.raise(ArgumentError)
   end
 
-  it "raises an Errno::EINVAL when not passed a valid offset" do
-    -> { IO.read @fname, 0, -1  }.should raise_error(Errno::EINVAL)
-    -> { IO.read @fname, -1, -1 }.should raise_error(Errno::EINVAL)
+  it "raises an ArgumentError when not passed a valid offset" do
+    -> { IO.read @fname, 0, -1  }.should.raise(ArgumentError)
+    -> { IO.read @fname, -1, -1 }.should.raise(ArgumentError)
   end
 
   it "uses the external encoding specified via the :external_encoding option" do
@@ -104,57 +140,89 @@ describe "IO.read" do
     str = IO.read(@fname, encoding: Encoding::ISO_8859_1)
     str.encoding.should == Encoding::ISO_8859_1
   end
-end
 
-describe "IO.read from a pipe" do
-  it "runs the rest as a subprocess and returns the standard output" do
-    cmd = "|sh -c 'echo hello'"
-    platform_is :windows do
-      cmd = "|cmd.exe /C echo hello"
+  platform_is :windows do
+    it "reads the file in text mode" do
+      # 0x1A is CTRL+Z and is EOF in Windows text mode.
+      File.binwrite(@fname, "\x1Abbb")
+      IO.read(@fname).should.empty?
     end
-    IO.read(cmd).should == "hello\n"
   end
+end
 
-  platform_is_not :windows do
-    it "opens a pipe to a fork if the rest is -" do
-      str = IO.read("|-")
-      if str # parent
-        str.should == "hello from child\n"
-      else #child
-        puts "hello from child"
-        exit!
+ruby_version_is ""..."4.0" do
+  describe "IO.read from a pipe" do
+    it "runs the rest as a subprocess and returns the standard output" do
+      cmd = "|sh -c 'echo hello'"
+      platform_is :windows do
+        cmd = "|cmd.exe /C echo hello"
+      end
+
+      suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+        IO.read(cmd).should == "hello\n"
       end
     end
-  end
 
-  it "reads only the specified number of bytes requested" do
-    cmd = "|sh -c 'echo hello'"
-    platform_is :windows do
-      cmd = "|cmd.exe /C echo hello"
+    platform_is_not :windows do
+      it "opens a pipe to a fork if the rest is -" do
+        str = nil
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          str = IO.read("|-")
+        end
+
+        if str # parent
+          str.should == "hello from child\n"
+        else #child
+          puts "hello from child"
+          exit!
+        end
+      end
     end
-    IO.read(cmd, 1).should == "h"
-  end
 
-  platform_is_not :windows do
-    it "raises Errno::ESPIPE if passed an offset" do
-      -> {
-        IO.read("|sh -c 'echo hello'", 1, 1)
-      }.should raise_error(Errno::ESPIPE)
+    it "reads only the specified number of bytes requested" do
+      cmd = "|sh -c 'echo hello'"
+      platform_is :windows do
+        cmd = "|cmd.exe /C echo hello"
+      end
+
+      suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+        IO.read(cmd, 1).should == "h"
+      end
     end
-  end
 
-quarantine! do # The process tried to write to a nonexistent pipe.
-  platform_is :windows do
-    # TODO: It should raise Errno::ESPIPE on Windows as well
-    # once https://bugs.ruby-lang.org/issues/12230 is fixed.
-    it "raises Errno::EINVAL if passed an offset" do
+    platform_is_not :windows do
+      it "raises Errno::ESPIPE if passed an offset" do
+        -> {
+          suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+            IO.read("|sh -c 'echo hello'", 1, 1)
+          end
+        }.should.raise(Errno::ESPIPE)
+      end
+    end
+
+    quarantine! do # The process tried to write to a nonexistent pipe.
+      platform_is :windows do
+        # TODO: It should raise Errno::ESPIPE on Windows as well
+        # once https://bugs.ruby-lang.org/issues/12230 is fixed.
+        it "raises Errno::EINVAL if passed an offset" do
+          -> {
+            suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+              IO.read("|cmd.exe /C echo hello", 1, 1)
+            end
+          }.should.raise(Errno::EINVAL)
+        end
+      end
+    end
+
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation" do
+      cmd = "|echo ok"
       -> {
-        IO.read("|cmd.exe /C echo hello", 1, 1)
-      }.should raise_error(Errno::EINVAL)
+        IO.read(cmd)
+      }.should complain(/IO process creation with a leading '\|'/)
     end
   end
 end
-end
 
 describe "IO.read on an empty file" do
   before :each do
@@ -197,26 +265,58 @@ describe "IO#read" do
     @io.read(4).should == '7890'
   end
 
+  it "treats first nil argument as no length limit" do
+    @io.read(nil).should == @contents
+  end
+
+  it "raises an ArgumentError when not passed a valid length" do
+    -> { @io.read(-1) }.should.raise(ArgumentError)
+  end
+
   it "clears the output buffer if there is nothing to read" do
     @io.pos = 10
 
-    buf = 'non-empty string'
+    buf = +'non-empty string'
 
     @io.read(10, buf).should == nil
 
     buf.should == ''
+
+    buf = +'non-empty string'
+
+    @io.read(nil, buf).should == ""
+
+    buf.should == ''
+
+    buf = +'non-empty string'
+
+    @io.read(0, buf).should == ""
+
+    buf.should == ''
+  end
+
+  it "raise FrozenError if the output buffer is frozen" do
+    @io.read
+    -> { @io.read(0, 'frozen-string'.freeze) }.should.raise(FrozenError)
+    -> { @io.read(1, 'frozen-string'.freeze) }.should.raise(FrozenError)
+    -> { @io.read(nil, 'frozen-string'.freeze) }.should.raise(FrozenError)
+  end
+
+  it "raise FrozenError if the output buffer is frozen (2)" do
+    @io.read
+    -> { @io.read(1, ''.freeze) }.should.raise(FrozenError)
   end
 
   it "consumes zero bytes when reading zero bytes" do
     @io.read(0).should == ''
     @io.pos.should == 0
 
-    @io.getc.chr.should == '1'
+    @io.getc.should == '1'
   end
 
   it "is at end-of-file when everything has been read" do
     @io.read
-    @io.eof?.should == true
+    @io.should.eof?
   end
 
   it "reads the contents of a file" do
@@ -224,50 +324,72 @@ describe "IO#read" do
   end
 
   it "places the specified number of bytes in the buffer" do
-    buf = ""
+    buf = +""
     @io.read 5, buf
 
     buf.should == "12345"
   end
 
   it "expands the buffer when too small" do
-    buf = "ABCDE"
+    buf = +"ABCDE"
     @io.read nil, buf
 
     buf.should == @contents
   end
 
   it "overwrites the buffer" do
-    buf = "ABCDEFGHIJ"
+    buf = +"ABCDEFGHIJ"
     @io.read nil, buf
 
     buf.should == @contents
   end
 
   it "truncates the buffer when too big" do
-    buf = "ABCDEFGHIJKLMNO"
+    buf = +"ABCDEFGHIJKLMNO"
     @io.read nil, buf
     buf.should == @contents
 
     @io.rewind
 
-    buf = "ABCDEFGHIJKLMNO"
+    buf = +"ABCDEFGHIJKLMNO"
     @io.read 5, buf
     buf.should == @contents[0..4]
   end
 
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @io.read(10, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
+  end
+
+  # https://bugs.ruby-lang.org/issues/20416
+  it "does not preserve the encoding of the given buffer when max length is not provided" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @io.read(nil, buffer)
+
+    buffer.encoding.should_not == Encoding::ISO_8859_1
+  end
+
   it "returns the given buffer" do
-    buf = ""
+    buf = +""
 
-    @io.read(nil, buf).should equal buf
+    @io.read(nil, buf).should.equal? buf
+  end
+
+  it "returns the given buffer when there is nothing to read" do
+    buf = +""
+
+    @io.read
+    @io.read(nil, buf).should.equal? buf
   end
 
   it "coerces the second argument to string and uses it as a buffer" do
-    buf = "ABCDE"
+    buf = +"ABCDE"
     obj = mock("buff")
     obj.should_receive(:to_str).any_number_of_times.and_return(buf)
 
-    @io.read(15, obj).should_not equal obj
+    @io.read(15, obj).should_not.equal? obj
     buf.should == @contents
   end
 
@@ -301,9 +423,12 @@ describe "IO#read" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.read }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.read }.should.raise(IOError)
   end
 
+  it "raises ArgumentError when length is less than 0" do
+    -> { @io.read(-1) }.should.raise(ArgumentError)
+  end
 
   platform_is_not :windows do
     it "raises IOError when stream is closed by another thread" do
@@ -319,7 +444,7 @@ describe "IO#read" do
       Thread.pass until t.stop?
       r.close
       t.join
-      t.value.should be_kind_of(IOError)
+      t.value.should.is_a?(IOError)
       w.close
     end
   end
@@ -384,13 +509,6 @@ describe "IO#read in binary mode" do
     xE2 = [226].pack('C*')
     result.should == ("abc" + xE2 + "def").force_encoding(Encoding::BINARY)
   end
-
-  it "does not transcode file contents when an internal encoding is specified" do
-    result = File.open(@name, "r:binary:utf-8") { |f| f.read }.chomp
-    result.encoding.should == Encoding::BINARY
-    xE2 = [226].pack('C*')
-    result.should == ("abc" + xE2 + "def").force_encoding(Encoding::BINARY)
-  end
 end
 
 describe "IO#read in text mode" do
@@ -460,20 +578,20 @@ describe :io_read_internal_encoding, shared: true do
   end
 
   it "sets the String encoding to the internal encoding" do
-    @io.read.encoding.should equal(Encoding::UTF_8)
+    @io.read.encoding.should.equal?(Encoding::UTF_8)
   end
 
   describe "when passed nil for limit" do
     it "sets the buffer to a transcoded String" do
-      result = @io.read(nil, buf = "")
-      buf.should equal(result)
+      result = @io.read(nil, buf = +"")
+      buf.should.equal?(result)
       buf.should == "ありがとう\n"
     end
 
     it "sets the buffer's encoding to the internal encoding" do
-      buf = "".force_encoding Encoding::ISO_8859_1
+      buf = "".dup.force_encoding Encoding::ISO_8859_1
       @io.read(nil, buf)
-      buf.encoding.should equal(Encoding::UTF_8)
+      buf.encoding.should.equal?(Encoding::UTF_8)
     end
   end
 end
@@ -484,23 +602,24 @@ describe :io_read_size_internal_encoding, shared: true do
   end
 
   it "returns a String in BINARY when passed a size" do
-    @io.read(4).encoding.should equal(Encoding::BINARY)
+    @io.read(4).encoding.should.equal?(Encoding::BINARY)
+    @io.read(0).encoding.should.equal?(Encoding::BINARY)
   end
 
   it "does not change the buffer's encoding when passed a limit" do
-    buf = "".force_encoding Encoding::ISO_8859_1
+    buf = "".dup.force_encoding Encoding::ISO_8859_1
     @io.read(4, buf)
     buf.should == [164, 162, 164, 234].pack('C*').force_encoding(Encoding::ISO_8859_1)
-    buf.encoding.should equal(Encoding::ISO_8859_1)
+    buf.encoding.should.equal?(Encoding::ISO_8859_1)
   end
 
   it "truncates the buffer but does not change the buffer's encoding when no data remains" do
-    buf = "abc".force_encoding Encoding::ISO_8859_1
+    buf = "abc".dup.force_encoding Encoding::ISO_8859_1
     @io.read
 
-    @io.read(1, buf).should be_nil
+    @io.read(1, buf).should == nil
     buf.size.should == 0
-    buf.encoding.should equal(Encoding::ISO_8859_1)
+    buf.encoding.should.equal?(Encoding::ISO_8859_1)
   end
 end
 
@@ -518,7 +637,7 @@ describe "IO#read" do
     end
 
     it "sets the String encoding to Encoding.default_external" do
-      @io.read.encoding.should equal(Encoding.default_external)
+      @io.read.encoding.should.equal?(Encoding.default_external)
     end
   end
 
@@ -537,7 +656,7 @@ describe "IO#read" do
       end
 
       it "sets the String encoding to the external encoding" do
-        @io.read.encoding.should equal(Encoding::EUC_JP)
+        @io.read.encoding.should.equal?(Encoding::EUC_JP)
       end
 
       it_behaves_like :io_read_size_internal_encoding, nil
diff --git a/spec/ruby/core/io/readbyte_spec.rb b/spec/ruby/core/io/readbyte_spec.rb
index 14426c28ac..07da1da919 100644
--- a/spec/ruby/core/io/readbyte_spec.rb
+++ b/spec/ruby/core/io/readbyte_spec.rb
@@ -19,6 +19,6 @@ describe "IO#readbyte" do
     @io.seek(999999)
     -> do
       @io.readbyte
-    end.should raise_error EOFError
+    end.should.raise EOFError
   end
 end
diff --git a/spec/ruby/core/io/readchar_spec.rb b/spec/ruby/core/io/readchar_spec.rb
index b5f762a846..29d14880ff 100644
--- a/spec/ruby/core/io/readchar_spec.rb
+++ b/spec/ruby/core/io/readchar_spec.rb
@@ -1,6 +1,16 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
+describe :io_readchar_internal_encoding, shared: true do
+  it "returns a transcoded String" do
+    @io.readchar.should == "あ"
+  end
+
+  it "sets the String encoding to the internal encoding" do
+    @io.readchar.encoding.should.equal?(Encoding::UTF_8)
+  end
+end
+
 describe "IO#readchar" do
   before :each do
     @io = IOSpecs.io_fixture "lines.txt"
@@ -21,11 +31,67 @@ describe "IO#readchar" do
 
   it "raises an EOFError when invoked at the end of the stream" do
     @io.read
-    -> { @io.readchar }.should raise_error(EOFError)
+    -> { @io.readchar }.should.raise(EOFError)
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.readchar }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.readchar }.should.raise(IOError)
+  end
+end
+
+describe "IO#readchar with internal encoding" do
+  after :each do
+    @io.close if @io
+  end
+
+  describe "not specified" do
+    before :each do
+      @io = IOSpecs.io_fixture "read_euc_jp.txt", "r:euc-jp"
+    end
+
+    it "does not transcode the String" do
+      @io.readchar.should == ("あ").encode(Encoding::EUC_JP)
+    end
+
+    it "sets the String encoding to the external encoding" do
+      @io.readchar.encoding.should.equal?(Encoding::EUC_JP)
+    end
+  end
+
+  describe "specified by open mode" do
+    before :each do
+      @io = IOSpecs.io_fixture "read_euc_jp.txt", "r:euc-jp:utf-8"
+    end
+
+    it_behaves_like :io_readchar_internal_encoding, nil
+  end
+
+  describe "specified by mode: option" do
+    before :each do
+      @io = IOSpecs.io_fixture "read_euc_jp.txt", mode: "r:euc-jp:utf-8"
+    end
+
+    it_behaves_like :io_readchar_internal_encoding, nil
+  end
+
+  describe "specified by internal_encoding: option" do
+    before :each do
+      options = { mode: "r",
+                  internal_encoding: "utf-8",
+                  external_encoding: "euc-jp" }
+      @io = IOSpecs.io_fixture "read_euc_jp.txt", options
+    end
+
+    it_behaves_like :io_readchar_internal_encoding, nil
+  end
+
+  describe "specified by encoding: option" do
+    before :each do
+      options = { mode: "r", encoding: "euc-jp:utf-8" }
+      @io = IOSpecs.io_fixture "read_euc_jp.txt", options
+    end
+
+    it_behaves_like :io_readchar_internal_encoding, nil
   end
 end
 
@@ -39,6 +105,6 @@ describe "IO#readchar" do
   end
 
   it "raises EOFError on empty stream" do
-    -> { @io.readchar }.should raise_error(EOFError)
+    -> { @io.readchar }.should.raise(EOFError)
   end
 end
diff --git a/spec/ruby/core/io/readline_spec.rb b/spec/ruby/core/io/readline_spec.rb
index 7cb1601816..009687710a 100644
--- a/spec/ruby/core/io/readline_spec.rb
+++ b/spec/ruby/core/io/readline_spec.rb
@@ -29,11 +29,11 @@ describe "IO#readline" do
 
   it "raises EOFError on end of stream" do
     IOSpecs.lines.length.times { @io.readline }
-    -> { @io.readline }.should raise_error(EOFError)
+    -> { @io.readline }.should.raise(EOFError)
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.readline }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.readline }.should.raise(IOError)
   end
 
   it "assigns the returned line to $_" do
@@ -43,9 +43,42 @@ describe "IO#readline" do
     end
   end
 
+  describe "when passed limit" do
+    it "reads limit bytes" do
+      @io.readline(3).should == "Voi"
+    end
+
+    it "returns an empty string when passed 0 as a limit" do
+      @io.readline(0).should == ""
+    end
+
+    it "does not accept Integers that don't fit in a C off_t" do
+      -> { @io.readline(2**128) }.should.raise(RangeError)
+    end
+  end
+
+  describe "when passed separator and limit" do
+    it "reads limit bytes till the separator" do
+      # Voici la ligne une.\
+      @io.readline(" ", 4).should == "Voic"
+      @io.readline(" ", 4).should == "i "
+      @io.readline(" ", 4).should == "la "
+      @io.readline(" ", 4).should == "lign"
+      @io.readline(" ", 4).should == "e "
+    end
+  end
+
   describe "when passed chomp" do
     it "returns the first line without a trailing newline character" do
       @io.readline(chomp: true).should == IOSpecs.lines_without_newline_characters[0]
     end
+
+    it "raises exception when options passed as Hash" do
+      -> { @io.readline({ chomp: true }) }.should.raise(TypeError)
+
+      -> {
+        @io.readline("\n", 1, { chomp: true })
+      }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 0..2)")
+    end
   end
 end
diff --git a/spec/ruby/core/io/readlines_spec.rb b/spec/ruby/core/io/readlines_spec.rb
index 0d4f002972..640e253200 100644
--- a/spec/ruby/core/io/readlines_spec.rb
+++ b/spec/ruby/core/io/readlines_spec.rb
@@ -17,16 +17,16 @@ describe "IO#readlines" do
 
   it "raises an IOError if the stream is closed" do
     @io.close
-    -> { @io.readlines }.should raise_error(IOError)
+    -> { @io.readlines }.should.raise(IOError)
   end
 
   describe "when passed no arguments" do
     before :each do
-      @sep, $/ = $/, " "
+      suppress_warning {@sep, $/ = $/, " "}
     end
 
     after :each do
-      $/ = @sep
+      suppress_warning {$/ = @sep}
     end
 
     it "returns an Array containing lines based on $/" do
@@ -37,12 +37,12 @@ describe "IO#readlines" do
   describe "when passed no arguments" do
     it "updates self's position" do
       @io.readlines
-      @io.pos.should eql(137)
+      @io.pos.should.eql?(137)
     end
 
     it "updates self's lineno based on the number of lines read" do
       @io.readlines
-      @io.lineno.should eql(9)
+      @io.lineno.should.eql?(9)
     end
 
     it "does not change $_" do
@@ -81,12 +81,12 @@ describe "IO#readlines" do
 
     it "updates self's lineno based on the number of lines read" do
       @io.readlines("r")
-      @io.lineno.should eql(5)
+      @io.lineno.should.eql?(5)
     end
 
     it "updates self's position based on the number of characters read" do
       @io.readlines("r")
-      @io.pos.should eql(137)
+      @io.pos.should.eql?(137)
     end
 
     it "does not change $_" do
@@ -102,28 +102,33 @@ describe "IO#readlines" do
     end
   end
 
-  describe "when passed a string that starts with a |" do
-    it "gets data from the standard out of the subprocess" do
-      cmd = "|sh -c 'echo hello;echo line2'"
-      platform_is :windows do
-        cmd = "|cmd.exe /C echo hello&echo line2"
-      end
-      lines = IO.readlines(cmd)
-      lines.should == ["hello\n", "line2\n"]
+  describe "when passed limit" do
+    it "raises ArgumentError when passed 0 as a limit" do
+      -> { @io.readlines(0) }.should.raise(ArgumentError)
     end
 
-    platform_is_not :windows do
-      it "gets data from a fork when passed -" do
-        lines = IO.readlines("|-")
+    it "does not accept Integers that don't fit in a C off_t" do
+      -> { @io.readlines(2**128) }.should.raise(RangeError)
+    end
+  end
 
-        if lines # parent
-          lines.should == ["hello\n", "from a fork\n"]
-        else
-          puts "hello"
-          puts "from a fork"
-          exit!
-        end
-      end
+  describe "when passed chomp" do
+    it "returns the first line without a trailing newline character" do
+      @io.readlines(chomp: true).should == IOSpecs.lines_without_newline_characters
+    end
+
+    it "raises exception when options passed as Hash" do
+      -> { @io.readlines({ chomp: true }) }.should.raise(TypeError)
+
+      -> {
+        @io.readlines("\n", 1, { chomp: true })
+      }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 0..2)")
+    end
+  end
+
+  describe "when passed arbitrary keyword argument" do
+    it "tolerates it" do
+      @io.readlines(chomp: true, foo: :bar).should == IOSpecs.lines_without_newline_characters
     end
   end
 end
@@ -140,13 +145,13 @@ describe "IO#readlines" do
   it "raises an IOError if the stream is opened for append only" do
     -> do
       File.open(@name, "a:utf-8") { |f| f.readlines }
-    end.should raise_error(IOError)
+    end.should.raise(IOError)
   end
 
   it "raises an IOError if the stream is opened for write only" do
     -> do
       File.open(@name, "w:utf-8") { |f| f.readlines }
-    end.should raise_error(IOError)
+    end.should.raise(IOError)
   end
 end
 
@@ -169,6 +174,48 @@ describe "IO.readlines" do
     $_.should == "test"
   end
 
+  ruby_version_is ""..."4.0" do
+    describe "when passed a string that starts with a |" do
+      it "gets data from the standard out of the subprocess" do
+        cmd = "|sh -c 'echo hello;echo line2'"
+        platform_is :windows do
+          cmd = "|cmd.exe /C echo hello&echo line2"
+        end
+
+        lines = nil
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          lines = IO.readlines(cmd)
+        end
+        lines.should == ["hello\n", "line2\n"]
+      end
+
+      platform_is_not :windows do
+        it "gets data from a fork when passed -" do
+          lines = nil
+          suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+            lines = IO.readlines("|-")
+          end
+
+          if lines # parent
+            lines.should == ["hello\n", "from a fork\n"]
+          else
+            puts "hello"
+            puts "from a fork"
+            exit!
+          end
+        end
+      end
+    end
+
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation given a path with a pipe" do
+      cmd = "|echo ok"
+      -> {
+        IO.readlines(cmd)
+      }.should complain(/IO process creation with a leading '\|'/)
+    end
+  end
+
   it_behaves_like :io_readlines, :readlines
   it_behaves_like :io_readlines_options_19, :readlines
 end
@@ -184,27 +231,27 @@ describe "IO.readlines" do
   after :each do
     Encoding.default_external = @external
     Encoding.default_internal = @internal
-    $/ = @dollar_slash
+    suppress_warning {$/ = @dollar_slash}
   end
 
   it "encodes lines using the default external encoding" do
     Encoding.default_external = Encoding::UTF_8
     lines = IO.readlines(@name)
-    lines.all? { |s| s.encoding == Encoding::UTF_8 }.should be_true
+    lines.all? { |s| s.encoding == Encoding::UTF_8 }.should == true
   end
 
   it "encodes lines using the default internal encoding, when set" do
     Encoding.default_external = Encoding::UTF_8
     Encoding.default_internal = Encoding::UTF_16
-    $/ = $/.encode Encoding::UTF_16
+    suppress_warning {$/ = $/.encode Encoding::UTF_16}
     lines = IO.readlines(@name)
-    lines.all? { |s| s.encoding == Encoding::UTF_16 }.should be_true
+    lines.all? { |s| s.encoding == Encoding::UTF_16 }.should == true
   end
 
   it "ignores the default internal encoding if the external encoding is BINARY" do
     Encoding.default_external = Encoding::BINARY
     Encoding.default_internal = Encoding::UTF_8
     lines = IO.readlines(@name)
-    lines.all? { |s| s.encoding == Encoding::BINARY }.should be_true
+    lines.all? { |s| s.encoding == Encoding::BINARY }.should == true
   end
 end
diff --git a/spec/ruby/core/io/readpartial_spec.rb b/spec/ruby/core/io/readpartial_spec.rb
index 2b33a0d5b1..d3f5545c8f 100644
--- a/spec/ruby/core/io/readpartial_spec.rb
+++ b/spec/ruby/core/io/readpartial_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -15,10 +15,10 @@ describe "IO#readpartial" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.readpartial(10) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.readpartial(10) }.should.raise(IOError)
 
     @rd.close
-    -> { @rd.readpartial(10) }.should raise_error(IOError)
+    -> { @rd.readpartial(10) }.should.raise(IOError)
   end
 
   it "reads at most the specified number of bytes" do
@@ -59,10 +59,10 @@ describe "IO#readpartial" do
   end
 
   it "discards the existing buffer content upon successful read" do
-    buffer = "existing"
+    buffer = +"existing content"
     @wr.write("hello world")
     @wr.close
-    @rd.readpartial(11, buffer)
+    @rd.readpartial(11, buffer).should.equal?(buffer)
     buffer.should == "hello world"
   end
 
@@ -70,27 +70,46 @@ describe "IO#readpartial" do
     @wr.write("abc")
     @wr.close
     @rd.readpartial(10).should == 'abc'
-    -> { @rd.readpartial(10) }.should raise_error(EOFError)
+    -> { @rd.readpartial(10) }.should.raise(EOFError)
   end
 
   it "discards the existing buffer content upon error" do
-    buffer = 'hello'
+    buffer = +'hello'
     @wr.close
-    -> { @rd.readpartial(1, buffer) }.should raise_error(EOFError)
-    buffer.should be_empty
+    -> { @rd.readpartial(1, buffer) }.should.raise(EOFError)
+    buffer.should.empty?
   end
 
   it "raises IOError if the stream is closed" do
     @wr.close
-    -> { @rd.readpartial(1) }.should raise_error(IOError)
+    -> { @rd.readpartial(1) }.should.raise(IOError)
   end
 
   it "raises ArgumentError if the negative argument is provided" do
-    -> { @rd.readpartial(-1) }.should raise_error(ArgumentError)
+    -> { @rd.readpartial(-1) }.should.raise(ArgumentError)
   end
 
   it "immediately returns an empty string if the length argument is 0" do
     @rd.readpartial(0).should == ""
   end
 
+  it "raises IOError if the stream is closed and the length argument is 0" do
+    @rd.close
+    -> { @rd.readpartial(0) }.should.raise(IOError, "closed stream")
+  end
+
+  it "clears and returns the given buffer if the length argument is 0" do
+    buffer = +"existing content"
+    @rd.readpartial(0, buffer).should == buffer
+    buffer.should == ""
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @wr.write("abc")
+    @wr.close
+    @rd.readpartial(10, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
+  end
 end
diff --git a/spec/ruby/core/io/reopen_spec.rb b/spec/ruby/core/io/reopen_spec.rb
index faef80f513..3b972d8978 100644
--- a/spec/ruby/core/io/reopen_spec.rb
+++ b/spec/ruby/core/io/reopen_spec.rb
@@ -27,35 +27,35 @@ describe "IO#reopen" do
   it "changes the class of the instance to the class of the object returned by #to_io" do
     obj = mock("io")
     obj.should_receive(:to_io).and_return(@other_io)
-    @io.reopen(obj).should be_an_instance_of(File)
+    @io.reopen(obj).should.instance_of?(File)
   end
 
   it "raises an IOError if the object returned by #to_io is closed" do
     obj = mock("io")
     obj.should_receive(:to_io).and_return(IOSpecs.closed_io)
-    -> { @io.reopen obj }.should raise_error(IOError)
+    -> { @io.reopen obj }.should.raise(IOError)
   end
 
   it "raises a TypeError if #to_io does not return an IO instance" do
     obj = mock("io")
     obj.should_receive(:to_io).and_return("something else")
-    -> { @io.reopen obj }.should raise_error(TypeError)
+    -> { @io.reopen obj }.should.raise(TypeError)
   end
 
   it "raises an IOError when called on a closed stream with an object" do
     @io.close
     obj = mock("io")
     obj.should_not_receive(:to_io)
-    -> { @io.reopen(STDOUT) }.should raise_error(IOError)
+    -> { @io.reopen(STDOUT) }.should.raise(IOError)
   end
 
   it "raises an IOError if the IO argument is closed" do
-    -> { @io.reopen(IOSpecs.closed_io) }.should raise_error(IOError)
+    -> { @io.reopen(IOSpecs.closed_io) }.should.raise(IOError)
   end
 
   it "raises an IOError when called on a closed stream with an IO" do
     @io.close
-    -> { @io.reopen(STDOUT) }.should raise_error(IOError)
+    -> { @io.reopen(STDOUT) }.should.raise(IOError)
   end
 end
 
@@ -77,12 +77,12 @@ describe "IO#reopen with a String" do
   it "does not raise an exception when called on a closed stream with a path" do
     @io.close
     @io.reopen @name, "r"
-    @io.closed?.should be_false
+    @io.closed?.should == false
     @io.gets.should == "Line 1: One\n"
   end
 
   it "returns self" do
-    @io.reopen(@name).should equal(@io)
+    @io.reopen(@name).should.equal?(@io)
   end
 
   it "positions a newly created instance at the beginning of the new stream" do
@@ -150,11 +150,11 @@ describe "IO#reopen with a String" do
 
     @io.close_on_exec = true
     @io.reopen @other_name
-    @io.close_on_exec?.should == true
+    @io.should.close_on_exec?
 
     @io.close_on_exec = false
     @io.reopen @other_name
-    @io.close_on_exec?.should == true
+    @io.should.close_on_exec?
   end
 
   it "creates the file if it doesn't exist if the IO is opened in write mode" do
@@ -188,7 +188,7 @@ describe "IO#reopen with a String" do
 
   it "raises an Errno::ENOENT if the file does not exist and the IO is not opened in write mode" do
     @io = new_io @name, "r"
-    -> { @io.reopen(@other_name) }.should raise_error(Errno::ENOENT)
+    -> { @io.reopen(@other_name) }.should.raise(Errno::ENOENT)
   end
 end
 
@@ -214,9 +214,9 @@ describe "IO#reopen with an IO at EOF" do
   end
 
   it "resets the EOF status to false" do
-    @io.eof?.should be_true
+    @io.eof?.should == true
     @io.reopen @other_io
-    @io.eof?.should be_false
+    @io.eof?.should == false
   end
 end
 
@@ -244,7 +244,7 @@ describe "IO#reopen with an IO" do
     # MRI actually changes the class of @io in the call to #reopen
     # but does not preserve the existing singleton class of @io.
     def @io.to_io; flunk; end
-    @io.reopen(@other_io).should be_an_instance_of(IO)
+    @io.reopen(@other_io).should.instance_of?(IO)
   end
 
   it "does not change the object_id" do
@@ -293,17 +293,17 @@ describe "IO#reopen with an IO" do
     @other_io.close_on_exec = true
     @io.close_on_exec = true
     @io.reopen @other_io
-    @io.close_on_exec?.should == true
+    @io.should.close_on_exec?
 
     @other_io.close_on_exec = false
     @io.close_on_exec = false
     @io.reopen @other_io
-    @io.close_on_exec?.should == true
+    @io.should.close_on_exec?
   end
 
   it "may change the class of the instance" do
     @io.reopen @other_io
-    @io.should be_an_instance_of(File)
+    @io.should.instance_of?(File)
   end
 
   it "sets path equals to the other IO's path if other IO is File" do
diff --git a/spec/ruby/core/io/rewind_spec.rb b/spec/ruby/core/io/rewind_spec.rb
index 954d56d30c..43834ef307 100644
--- a/spec/ruby/core/io/rewind_spec.rb
+++ b/spec/ruby/core/io/rewind_spec.rb
@@ -18,10 +18,21 @@ describe "IO#rewind" do
     @io.readline.should == "Voici la ligne une.\n"
   end
 
+  it "positions the instance to the beginning of output for write-only IO" do
+    name = tmp("io_rewind_spec")
+    io = File.open(name, "w")
+    io.write("Voici la ligne une.\n")
+    io.rewind
+    io.pos.should == 0
+  ensure
+    io.close
+    rm_r name
+  end
+
   it "positions the instance to the beginning of input and clears EOF" do
     value = @io.read
     @io.rewind
-    @io.eof?.should == false
+    @io.should_not.eof?
     value.should == @io.read
   end
 
@@ -32,7 +43,11 @@ describe "IO#rewind" do
     @io.lineno.should == 0
   end
 
+  it "returns 0" do
+    @io.rewind.should == 0
+  end
+
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.rewind }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.rewind }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/seek_spec.rb b/spec/ruby/core/io/seek_spec.rb
index 7e9c308272..d26629fb89 100644
--- a/spec/ruby/core/io/seek_spec.rb
+++ b/spec/ruby/core/io/seek_spec.rb
@@ -17,7 +17,7 @@ describe "IO#seek" do
   end
 
   it "moves the read position relative to the current position with SEEK_CUR" do
-    -> { @io.seek(-1) }.should raise_error(Errno::EINVAL)
+    -> { @io.seek(-1) }.should.raise(Errno::EINVAL)
     @io.seek(10, IO::SEEK_CUR)
     @io.readline.should == "igne une.\n"
     @io.seek(-5, IO::SEEK_CUR)
@@ -44,21 +44,21 @@ describe "IO#seek" do
   it "moves the read position and clears EOF with SEEK_SET" do
     value = @io.read
     @io.seek(0, IO::SEEK_SET)
-    @io.eof?.should == false
+    @io.should_not.eof?
     value.should == @io.read
   end
 
   it "moves the read position and clears EOF with SEEK_CUR" do
     value = @io.read
     @io.seek(-1, IO::SEEK_CUR)
-    @io.eof?.should == false
+    @io.should_not.eof?
     value[-1].should == @io.read[0]
   end
 
   it "moves the read position and clears EOF with SEEK_END" do
     value = @io.read
     @io.seek(-1, IO::SEEK_END)
-    @io.eof?.should == false
+    @io.should_not.eof?
     value[-1].should == @io.read[0]
   end
 
diff --git a/spec/ruby/core/io/select_spec.rb b/spec/ruby/core/io/select_spec.rb
index 4603c1fbbc..0a43fc6f5f 100644
--- a/spec/ruby/core/io/select_spec.rb
+++ b/spec/ruby/core/io/select_spec.rb
@@ -18,6 +18,10 @@ describe "IO.select" do
     @wr.syswrite("be ready")
     IO.pipe do |_, wr|
       result = IO.select [@rd], [wr], nil, 0
+      unless result
+        # On some platforms (e.g., Windows), pipe readiness may not be immediate
+        result = IO.select [@rd], [wr], nil, 2
+      end
       result.should == [[@rd], [wr], []]
     end
   end
@@ -55,8 +59,8 @@ describe "IO.select" do
     end
   end
 
-  it "returns supplied objects correctly even when monitoring the same object in different arrays" do
-    filename = tmp("IO_select_pipe_file") + $$.to_s
+  it "returns supplied objects correctly when monitoring the same object in different arrays" do
+    filename = tmp("IO_select_pipe_file")
     io = File.open(filename, 'w+')
     result = IO.select [io], [io], nil, 0
     result.should == [[io], [io], []]
@@ -64,6 +68,17 @@ describe "IO.select" do
     rm_r filename
   end
 
+  it "returns the pipe read end in read set if the pipe write end is closed concurrently" do
+    main = Thread.current
+    t = Thread.new {
+      Thread.pass until main.stop?
+      @wr.close
+    }
+    IO.select([@rd]).should == [[@rd], [], []]
+  ensure
+    t.join
+  end
+
   it "invokes to_io on supplied objects that are not IO and returns the supplied objects" do
     # make some data available
     @wr.write("foobar")
@@ -80,41 +95,96 @@ describe "IO.select" do
   end
 
   it "raises TypeError if supplied objects are not IO" do
-    -> { IO.select([Object.new]) }.should raise_error(TypeError)
-    -> { IO.select(nil, [Object.new]) }.should raise_error(TypeError)
+    -> { IO.select([Object.new]) }.should.raise(TypeError)
+    -> { IO.select(nil, [Object.new]) }.should.raise(TypeError)
 
     obj = mock("io")
     obj.should_receive(:to_io).any_number_of_times.and_return(nil)
 
-    -> { IO.select([obj]) }.should raise_error(TypeError)
-    -> { IO.select(nil, [obj]) }.should raise_error(TypeError)
+    -> { IO.select([obj]) }.should.raise(TypeError)
+    -> { IO.select(nil, [obj]) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the specified timeout value is not Numeric" do
-    -> { IO.select([@rd], nil, nil, Object.new) }.should raise_error(TypeError)
+    -> { IO.select([@rd], nil, nil, Object.new) }.should.raise(TypeError)
   end
 
   it "raises TypeError if the first three arguments are not Arrays" do
-    -> { IO.select(Object.new)}.should raise_error(TypeError)
-    -> { IO.select(nil, Object.new)}.should raise_error(TypeError)
-    -> { IO.select(nil, nil, Object.new)}.should raise_error(TypeError)
+    -> { IO.select(Object.new)}.should.raise(TypeError)
+    -> { IO.select(nil, Object.new)}.should.raise(TypeError)
+    -> { IO.select(nil, nil, Object.new)}.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when passed a negative timeout" do
-    -> { IO.select(nil, nil, nil, -5)}.should raise_error(ArgumentError)
+    -> { IO.select(nil, nil, nil, -5)}.should.raise(ArgumentError, "time interval must not be negative")
+  end
+
+  ruby_version_is "4.0" do
+    it "raises an ArgumentError when passed negative infinity as timeout" do
+      -> { IO.select(nil, nil, nil, -Float::INFINITY)}.should.raise(ArgumentError, "time interval must not be negative")
+    end
+  end
+
+  it "raises an RangeError when passed NaN as timeout" do
+    -> { IO.select(nil, nil, nil, Float::NAN)}.should.raise(RangeError, "NaN out of Time range")
+  end
+
+  describe "returns the available descriptors when the file descriptor" do
+    it "is in both read and error arrays" do
+      @wr.write("foobar")
+      result = IO.select([@rd], nil, [@rd])
+      result.should == [[@rd], [], []]
+    end
+
+    it "is in both write and error arrays" do
+      result = IO.select(nil, [@wr], [@wr])
+      result.should == [[], [@wr], []]
+    end
+
+    it "is in both read and write arrays" do
+      filename = tmp("IO_select_read_write_file")
+      w = File.open(filename, 'w+')
+      begin
+        IO.select([w], [w], []).should == [[w], [w], []]
+      ensure
+        w.close
+        rm_r filename
+      end
+
+      IO.select([@wr], [@wr], []).should == [[], [@wr], []]
+
+      @wr.write("foobar")
+      # CRuby on macOS returns [[@rd], [@rd], []], weird but we accept it here, probably only for pipe read-end
+      [
+        [[@rd], [], []],
+        [[@rd], [@rd], []]
+      ].should.include? IO.select([@rd], [@rd], [])
+    end
   end
 end
 
-describe "IO.select when passed nil for timeout" do
-  it "sleeps forever and sets the thread status to 'sleep'" do
-    t = Thread.new do
-      IO.select(nil, nil, nil, nil)
+describe "IO.select with infinite timeout" do
+  describe :io_select_infinite_timeout, shared: true do
+    it "sleeps forever and sets the thread status to 'sleep'" do
+      t = Thread.new do
+        IO.select(nil, nil, nil, @method)
+      end
+
+      Thread.pass while t.status && t.status != "sleep"
+      t.join unless t.status
+      t.status.should == "sleep"
+      t.kill
+      t.join
     end
+  end
 
-    Thread.pass while t.status && t.status != "sleep"
-    t.join unless t.status
-    t.status.should == "sleep"
-    t.kill
-    t.join
+  describe "IO.select when passed nil for timeout" do
+    it_behaves_like :io_select_infinite_timeout, nil
+  end
+
+  ruby_version_is "4.0" do
+    describe "IO.select when passed Float::INFINITY for timeout" do
+      it_behaves_like :io_select_infinite_timeout, Float::INFINITY
+    end
   end
 end
diff --git a/spec/ruby/core/io/set_encoding_by_bom_spec.rb b/spec/ruby/core/io/set_encoding_by_bom_spec.rb
new file mode 100644
index 0000000000..5436879f11
--- /dev/null
+++ b/spec/ruby/core/io/set_encoding_by_bom_spec.rb
@@ -0,0 +1,262 @@
+require_relative '../../spec_helper'
+
+describe "IO#set_encoding_by_bom" do
+  before :each do
+    @name = tmp('io_set_encoding_by_bom.txt')
+    touch(@name)
+    @io = new_io(@name, 'rb')
+  end
+
+  after :each do
+    @io.close unless @io.closed?
+    rm_r @name
+  end
+
+  it "returns nil if not readable" do
+    not_readable_io = new_io(@name, 'wb')
+
+    not_readable_io.set_encoding_by_bom.should == nil
+    not_readable_io.external_encoding.should == Encoding::ASCII_8BIT
+  ensure
+    not_readable_io.close
+  end
+
+  it "returns the result encoding if found BOM UTF-8 sequence" do
+    File.binwrite(@name, "\u{FEFF}")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_8
+    @io.external_encoding.should == Encoding::UTF_8
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.binwrite(@name, "\u{FEFF}abc")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_8
+    @io.external_encoding.should == Encoding::UTF_8
+    @io.read.b.should == "abc".b
+  end
+
+  it "returns the result encoding if found BOM UTF_16LE sequence" do
+    File.binwrite(@name, "\xFF\xFE")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16LE
+    @io.external_encoding.should == Encoding::UTF_16LE
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.binwrite(@name, "\xFF\xFEabc")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16LE
+    @io.external_encoding.should == Encoding::UTF_16LE
+    @io.read.b.should == "abc".b
+  end
+
+  it "returns the result encoding if found BOM UTF_16BE sequence" do
+    File.binwrite(@name, "\xFE\xFF")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16BE
+    @io.external_encoding.should == Encoding::UTF_16BE
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.binwrite(@name, "\xFE\xFFabcd")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16BE
+    @io.external_encoding.should == Encoding::UTF_16BE
+    @io.read.b.should == "abcd".b
+  end
+
+  it "returns the result encoding if found BOM UTF_32LE sequence" do
+    File.binwrite(@name, "\xFF\xFE\x00\x00")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_32LE
+    @io.external_encoding.should == Encoding::UTF_32LE
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.binwrite(@name, "\xFF\xFE\x00\x00abc")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_32LE
+    @io.external_encoding.should == Encoding::UTF_32LE
+    @io.read.b.should == "abc".b
+  end
+
+  it "returns the result encoding if found BOM UTF_32BE sequence" do
+    File.binwrite(@name, "\x00\x00\xFE\xFF")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_32BE
+    @io.external_encoding.should == Encoding::UTF_32BE
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.binwrite(@name, "\x00\x00\xFE\xFFabcd")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_32BE
+    @io.external_encoding.should == Encoding::UTF_32BE
+    @io.read.b.should == "abcd".b
+  end
+
+  it "returns nil if io is empty" do
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+  end
+
+  it "returns nil if UTF-8 BOM sequence is incomplete" do
+    File.write(@name, "\xEF")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xEF".b
+    @io.rewind
+
+    File.write(@name, "\xEFa")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xEFa".b
+    @io.rewind
+
+    File.write(@name, "\xEF\xBB")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xEF\xBB".b
+    @io.rewind
+
+    File.write(@name, "\xEF\xBBa")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xEF\xBBa".b
+  end
+
+  it "returns nil if UTF-16BE BOM sequence is incomplete" do
+    File.write(@name, "\xFE")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xFE".b
+    @io.rewind
+
+    File.write(@name, "\xFEa")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xFEa".b
+  end
+
+  it "returns nil if UTF-16LE/UTF-32LE BOM sequence is incomplete" do
+    File.write(@name, "\xFF")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xFF".b
+    @io.rewind
+
+    File.write(@name, "\xFFa")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\xFFa".b
+  end
+
+  it "returns UTF-16LE if UTF-32LE BOM sequence is incomplete" do
+    File.write(@name, "\xFF\xFE")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16LE
+    @io.external_encoding.should == Encoding::UTF_16LE
+    @io.read.b.should == "".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.write(@name, "\xFF\xFE\x00")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16LE
+    @io.external_encoding.should == Encoding::UTF_16LE
+    @io.read.b.should == "\x00".b
+    @io.rewind
+    @io.set_encoding(Encoding::ASCII_8BIT)
+
+    File.write(@name, "\xFF\xFE\x00a")
+
+    @io.set_encoding_by_bom.should == Encoding::UTF_16LE
+    @io.external_encoding.should == Encoding::UTF_16LE
+    @io.read.b.should == "\x00a".b
+  end
+
+  it "returns nil if UTF-32BE BOM sequence is incomplete" do
+    File.write(@name, "\x00")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00".b
+    @io.rewind
+
+    File.write(@name, "\x00a")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00a".b
+    @io.rewind
+
+    File.write(@name, "\x00\x00")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00\x00".b
+    @io.rewind
+
+    File.write(@name, "\x00\x00a")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00\x00a".b
+    @io.rewind
+
+    File.write(@name, "\x00\x00\xFE")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00\x00\xFE".b
+    @io.rewind
+
+    File.write(@name, "\x00\x00\xFEa")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read.b.should == "\x00\x00\xFEa".b
+  end
+
+  it "returns nil if found BOM sequence not provided" do
+    File.write(@name, "abc")
+
+    @io.set_encoding_by_bom.should == nil
+    @io.external_encoding.should == Encoding::ASCII_8BIT
+    @io.read(3).should == "abc".b
+  end
+
+  it 'returns exception if io not in binary mode' do
+    not_binary_io = new_io(@name, 'r')
+
+    -> { not_binary_io.set_encoding_by_bom }.should.raise(ArgumentError, 'ASCII incompatible encoding needs binmode')
+  ensure
+    not_binary_io.close
+  end
+
+  it 'returns exception if encoding already set' do
+    @io.set_encoding("utf-8")
+
+    -> { @io.set_encoding_by_bom }.should.raise(ArgumentError, 'encoding is set to UTF-8 already')
+  end
+
+  it 'returns exception if encoding conversion is already set' do
+    @io.set_encoding(Encoding::UTF_8, Encoding::UTF_16BE)
+
+    -> { @io.set_encoding_by_bom }.should.raise(ArgumentError, 'encoding conversion is set')
+  end
+end
diff --git a/spec/ruby/core/io/set_encoding_spec.rb b/spec/ruby/core/io/set_encoding_spec.rb
index 5aec6a96c3..237251de5b 100644
--- a/spec/ruby/core/io/set_encoding_spec.rb
+++ b/spec/ruby/core/io/set_encoding_spec.rb
@@ -1,12 +1,25 @@
 require_relative '../../spec_helper'
 
 describe :io_set_encoding_write, shared: true do
-  it "sets the encodings to nil" do
+  it "sets the encodings to nil when they were set previously" do
     @io = new_io @name, "#{@object}:ibm437:ibm866"
     @io.set_encoding nil, nil
 
-    @io.external_encoding.should be_nil
-    @io.internal_encoding.should be_nil
+    @io.external_encoding.should == nil
+    @io.internal_encoding.should == nil
+  end
+
+  it "sets the encodings to nil when the IO is built with no explicit encoding" do
+    @io = new_io @name, @object
+
+    # Checking our assumptions first
+    @io.external_encoding.should == nil
+    @io.internal_encoding.should == nil
+
+    @io.set_encoding nil, nil
+
+    @io.external_encoding.should == nil
+    @io.internal_encoding.should == nil
   end
 
   it "prevents the encodings from changing when Encoding defaults are changed" do
@@ -16,8 +29,8 @@ describe :io_set_encoding_write, shared: true do
     Encoding.default_external = Encoding::IBM437
     Encoding.default_internal = Encoding::IBM866
 
-    @io.external_encoding.should be_nil
-    @io.internal_encoding.should be_nil
+    @io.external_encoding.should == nil
+    @io.internal_encoding.should == nil
   end
 
   it "sets the encodings to the current Encoding defaults" do
@@ -38,6 +51,7 @@ describe "IO#set_encoding when passed nil, nil" do
     @external = Encoding.default_external
     @internal = Encoding.default_internal
 
+    # The defaults
     Encoding.default_external = Encoding::UTF_8
     Encoding.default_internal = nil
 
@@ -61,8 +75,8 @@ describe "IO#set_encoding when passed nil, nil" do
       Encoding.default_internal = Encoding::IBM866
 
       @io.set_encoding nil, nil
-      @io.external_encoding.should equal(Encoding::IBM437)
-      @io.internal_encoding.should equal(Encoding::IBM866)
+      @io.external_encoding.should.equal?(Encoding::IBM437)
+      @io.internal_encoding.should.equal?(Encoding::IBM866)
     end
 
     it "prevents the #internal_encoding from changing when Encoding.default_internal is changed" do
@@ -71,7 +85,7 @@ describe "IO#set_encoding when passed nil, nil" do
 
       Encoding.default_internal = Encoding::IBM437
 
-      @io.internal_encoding.should be_nil
+      @io.internal_encoding.should == nil
     end
 
     it "allows the #external_encoding to change when Encoding.default_external is changed" do
@@ -80,17 +94,17 @@ describe "IO#set_encoding when passed nil, nil" do
 
       Encoding.default_external = Encoding::IBM437
 
-      @io.external_encoding.should equal(Encoding::IBM437)
+      @io.external_encoding.should.equal?(Encoding::IBM437)
     end
   end
 
   describe "with 'rb' mode" do
     it "returns Encoding.default_external" do
       @io = new_io @name, "rb"
-      @io.external_encoding.should equal(Encoding::BINARY)
+      @io.external_encoding.should.equal?(Encoding::BINARY)
 
       @io.set_encoding nil, nil
-      @io.external_encoding.should equal(Encoding.default_external)
+      @io.external_encoding.should.equal?(Encoding.default_external)
     end
   end
 
@@ -113,6 +127,22 @@ describe "IO#set_encoding when passed nil, nil" do
   describe "with 'a+' mode" do
     it_behaves_like :io_set_encoding_write, nil, "a+"
   end
+
+  describe "with standard IOs" do
+    it "correctly resets them" do
+      STDOUT.external_encoding.should == nil
+      STDOUT.internal_encoding.should == nil
+
+      begin
+        STDOUT.set_encoding(Encoding::US_ASCII, Encoding::ISO_8859_1)
+      ensure
+        STDOUT.set_encoding(nil, nil)
+      end
+
+      STDOUT.external_encoding.should == nil
+      STDOUT.internal_encoding.should == nil
+    end
+  end
 end
 
 describe "IO#set_encoding" do
@@ -128,13 +158,13 @@ describe "IO#set_encoding" do
   end
 
   it "returns self" do
-    @io.set_encoding(Encoding::UTF_8).should equal(@io)
+    @io.set_encoding(Encoding::UTF_8).should.equal?(@io)
   end
 
   it "sets the external encoding when passed an Encoding argument" do
     @io.set_encoding(Encoding::UTF_8)
     @io.external_encoding.should == Encoding::UTF_8
-    @io.internal_encoding.should be_nil
+    @io.internal_encoding.should == nil
   end
 
   it "sets the external and internal encoding when passed two Encoding arguments" do
@@ -146,19 +176,19 @@ describe "IO#set_encoding" do
   it "sets the external encoding when passed the name of an Encoding" do
     @io.set_encoding("utf-8")
     @io.external_encoding.should == Encoding::UTF_8
-    @io.internal_encoding.should be_nil
+    @io.internal_encoding.should == nil
   end
 
   it "ignores the internal encoding if the same as external when passed Encoding objects" do
     @io.set_encoding(Encoding::UTF_8, Encoding::UTF_8)
     @io.external_encoding.should == Encoding::UTF_8
-    @io.internal_encoding.should be_nil
+    @io.internal_encoding.should == nil
   end
 
   it "ignores the internal encoding if the same as external when passed encoding names separated by ':'" do
     @io.set_encoding("utf-8:utf-8")
     @io.external_encoding.should == Encoding::UTF_8
-    @io.internal_encoding.should be_nil
+    @io.internal_encoding.should == nil
   end
 
   it "sets the external and internal encoding when passed the names of Encodings separated by ':'" do
@@ -188,4 +218,21 @@ describe "IO#set_encoding" do
     @io.external_encoding.should == Encoding::UTF_8
     @io.internal_encoding.should == Encoding::UTF_16BE
   end
+
+  it "saves encoding options passed as a hash in the last argument" do
+    File.write(@name, "\xff")
+    io = File.open(@name)
+    io.set_encoding(Encoding::EUC_JP, Encoding::SHIFT_JIS, invalid: :replace, replace: ".")
+    io.read.should == "."
+  ensure
+    io.close
+  end
+
+  it "raises ArgumentError when no arguments are given" do
+    -> { @io.set_encoding() }.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError when too many arguments are given" do
+    -> { @io.set_encoding(1, 2, 3) }.should.raise(ArgumentError)
+  end
 end
diff --git a/spec/ruby/core/io/shared/binwrite.rb b/spec/ruby/core/io/shared/binwrite.rb
index 3649bb47ff..64793b1936 100644
--- a/spec/ruby/core/io/shared/binwrite.rb
+++ b/spec/ruby/core/io/shared/binwrite.rb
@@ -21,6 +21,14 @@ describe :io_binwrite, shared: true do
     IO.send(@method, @filename, "abcde").should == 5
   end
 
+  it "accepts options as a keyword argument" do
+    IO.send(@method, @filename, "hi", 0, flags: File::CREAT).should == 2
+
+    -> {
+      IO.send(@method, @filename, "hi", 0, {flags: File::CREAT})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 2..3)")
+  end
+
   it "creates a file if missing" do
     fn = @filename + "xxx"
     begin
@@ -67,8 +75,13 @@ describe :io_binwrite, shared: true do
     File.read(@filename).should == "\0\0foo"
   end
 
+  it "accepts a :flags option without :mode one" do
+    IO.send(@method, @filename, "hello, world!", flags: File::CREAT)
+    File.read(@filename).should == "hello, world!"
+  end
+
   it "raises an error if readonly mode is specified" do
-    -> { IO.send(@method, @filename, "abcde", mode: "r") }.should raise_error(IOError)
+    -> { IO.send(@method, @filename, "abcde", mode: "r") }.should.raise(IOError)
   end
 
   it "truncates if empty :opts provided and offset skipped" do
diff --git a/spec/ruby/core/io/shared/chars.rb b/spec/ruby/core/io/shared/chars.rb
index 266566f221..efd4d5ee10 100644
--- a/spec/ruby/core/io/shared/chars.rb
+++ b/spec/ruby/core/io/shared/chars.rb
@@ -24,7 +24,7 @@ describe :io_chars, shared: true do
   describe "when no block is given" do
     it "returns an Enumerator" do
       enum = @io.send(@method)
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.first(5).should == ["V", "o", "i", "c", "i"]
     end
 
@@ -38,19 +38,19 @@ describe :io_chars, shared: true do
   end
 
   it "returns itself" do
-    @io.send(@method) { |c| }.should equal(@io)
+    @io.send(@method) { |c| }.should.equal?(@io)
   end
 
   it "returns an enumerator for a closed stream" do
-    IOSpecs.closed_io.send(@method).should be_an_instance_of(Enumerator)
+    IOSpecs.closed_io.send(@method).should.instance_of?(Enumerator)
   end
 
   it "raises an IOError when an enumerator created on a closed stream is accessed" do
-    -> { IOSpecs.closed_io.send(@method).first }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send(@method).first }.should.raise(IOError)
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.send(@method) {} }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send(@method) {} }.should.raise(IOError)
   end
 end
 
diff --git a/spec/ruby/core/io/shared/codepoints.rb b/spec/ruby/core/io/shared/codepoints.rb
index 6872846c1a..21c756986f 100644
--- a/spec/ruby/core/io/shared/codepoints.rb
+++ b/spec/ruby/core/io/shared/codepoints.rb
@@ -13,7 +13,7 @@ describe :io_codepoints, shared: true do
 
   describe "when no block is given" do
     it "returns an Enumerator" do
-      @enum.should be_an_instance_of(Enumerator)
+      @enum.should.instance_of?(Enumerator)
     end
 
     describe "returned Enumerator" do
@@ -39,7 +39,7 @@ describe :io_codepoints, shared: true do
 
   it "raises an error if reading invalid sequence" do
     @io.pos = 60  # inside of a multibyte sequence
-    -> { @enum.first }.should raise_error(ArgumentError)
+    -> { @enum.first }.should.raise(ArgumentError)
   end
 
   it "does not change $_" do
@@ -49,6 +49,6 @@ describe :io_codepoints, shared: true do
   end
 
   it "raises an IOError when self is not readable" do
-    -> { IOSpecs.closed_io.send(@method).to_a }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send(@method).to_a }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/shared/each.rb b/spec/ruby/core/io/shared/each.rb
index 0b2dfa3548..ae60c3506a 100644
--- a/spec/ruby/core/io/shared/each.rb
+++ b/spec/ruby/core/io/shared/each.rb
@@ -24,7 +24,7 @@ describe :io_each, shared: true do
     end
 
     it "returns self" do
-      @io.send(@method) { |l| l }.should equal(@io)
+      @io.send(@method) { |l| l }.should.equal?(@io)
     end
 
     it "does not change $_" do
@@ -33,12 +33,8 @@ describe :io_each, shared: true do
       $_.should == "test"
     end
 
-    it "returns self" do
-      @io.send(@method) { |l| l }.should equal(@io)
-    end
-
     it "raises an IOError when self is not readable" do
-      -> { IOSpecs.closed_io.send(@method) {} }.should raise_error(IOError)
+      -> { IOSpecs.closed_io.send(@method) {} }.should.raise(IOError)
     end
 
     it "makes line count accessible via lineno" do
@@ -54,7 +50,7 @@ describe :io_each, shared: true do
     describe "when no block is given" do
       it "returns an Enumerator" do
         enum = @io.send(@method)
-        enum.should be_an_instance_of(Enumerator)
+        enum.should.instance_of?(Enumerator)
 
         enum.each { |l| ScratchPad << l }
         ScratchPad.recorded.should == IOSpecs.lines
@@ -74,9 +70,13 @@ describe :io_each, shared: true do
     describe "when limit is 0" do
       it "raises an ArgumentError" do
         # must pass block so Enumerator is evaluated and raises
-        -> { @io.send(@method, 0){} }.should raise_error(ArgumentError)
+        -> { @io.send(@method, 0){} }.should.raise(ArgumentError)
       end
     end
+
+    it "does not accept Integers that don't fit in a C off_t" do
+      -> { @io.send(@method, 2**128){} }.should.raise(RangeError)
+    end
   end
 
   describe "when passed a String containing one space as a separator" do
@@ -113,13 +113,20 @@ describe :io_each, shared: true do
       @io.send(@method, "") { |s| ScratchPad << s }
       ScratchPad.recorded.should == IOSpecs.paragraphs
     end
+
+    it "discards leading newlines" do
+      @io.readline
+      @io.readline
+      @io.send(@method, "") { |s| ScratchPad << s }
+      ScratchPad.recorded.should == IOSpecs.paragraphs[1..-1]
+    end
   end
 
   describe "with both separator and limit" do
     describe "when no block is given" do
       it "returns an Enumerator" do
         enum = @io.send(@method, nil, 1024)
-        enum.should be_an_instance_of(Enumerator)
+        enum.should.instance_of?(Enumerator)
 
         enum.each { |l| ScratchPad << l }
         ScratchPad.recorded.should == [IOSpecs.lines.join]
@@ -136,7 +143,7 @@ describe :io_each, shared: true do
 
     describe "when a block is given" do
       it "accepts an empty block" do
-        @io.send(@method, nil, 1024) {}.should equal(@io)
+        @io.send(@method, nil, 1024) {}.should.equal?(@io)
       end
 
       describe "when passed nil as a separator" do
@@ -152,6 +159,13 @@ describe :io_each, shared: true do
           @io.send(@method, "", 1024) { |s| ScratchPad << s }
           ScratchPad.recorded.should == IOSpecs.paragraphs
         end
+
+        it "discards leading newlines" do
+          @io.readline
+          @io.readline
+          @io.send(@method, "", 1024) { |s| ScratchPad << s }
+          ScratchPad.recorded.should == IOSpecs.paragraphs[1..-1]
+        end
       end
     end
   end
@@ -161,6 +175,60 @@ describe :io_each, shared: true do
       @io.send(@method, chomp: true) { |s| ScratchPad << s }
       ScratchPad.recorded.should == IOSpecs.lines_without_newline_characters
     end
+
+    it "raises exception when options passed as Hash" do
+      -> {
+        @io.send(@method, { chomp: true }) { |s| }
+      }.should.raise(TypeError)
+
+      -> {
+        @io.send(@method, "\n", 1, { chomp: true }) { |s| }
+      }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 0..2)")
+    end
+  end
+
+  describe "when passed chomp and a separator" do
+    it "yields each line without separator to the passed block" do
+      @io.send(@method, " ", chomp: true) { |s| ScratchPad << s }
+      ScratchPad.recorded.should == IOSpecs.lines_space_separator_without_trailing_spaces
+    end
+  end
+
+  describe "when passed chomp and empty line as a separator" do
+    it "yields each paragraph without trailing new line characters" do
+      @io.send(@method, "", 1024, chomp: true) { |s| ScratchPad << s }
+      ScratchPad.recorded.should == IOSpecs.paragraphs_without_trailing_new_line_characters
+    end
+  end
+
+  describe "when passed chomp and nil as a separator" do
+    it "yields self's content" do
+      @io.pos = 100
+      @io.send(@method, nil, chomp: true) { |s| ScratchPad << s }
+      ScratchPad.recorded.should == ["qui a linha cinco.\nHere is line six.\n"]
+    end
+  end
+
+  describe "when passed chomp, nil as a separator, and a limit" do
+    it "yields each line of limit size without truncating trailing new line character" do
+      # 43 - is a size of the 1st paragraph in the file
+      @io.send(@method, nil, 43, chomp: true) { |s| ScratchPad << s }
+
+      ScratchPad.recorded.should == [
+        "Voici la ligne une.\nQui è la linea due.\n\n\n",
+        "Aquí está la línea tres.\n" + "Hier ist Zeile ",
+        "vier.\n\nEstá aqui a linha cinco.\nHere is li",
+        "ne six.\n"
+      ]
+    end
+  end
+
+  describe "when passed too many arguments" do
+    it "raises ArgumentError" do
+      -> {
+        @io.send(@method, "", 1, "excess argument", chomp: true) {}
+      }.should.raise(ArgumentError)
+    end
   end
 end
 
@@ -168,12 +236,12 @@ describe :io_each_default_separator, shared: true do
   before :each do
     @io = IOSpecs.io_fixture "lines.txt"
     ScratchPad.record []
-    @sep, $/ = $/, " "
+    suppress_warning {@sep, $/ = $/, " "}
   end
 
   after :each do
     @io.close if @io
-    $/ = @sep
+    suppress_warning {$/ = @sep}
   end
 
   it "uses $/ as the default line separator" do
diff --git a/spec/ruby/core/io/shared/gets_ascii.rb b/spec/ruby/core/io/shared/gets_ascii.rb
index 2a8fe3c9a5..2bd5470d99 100644
--- a/spec/ruby/core/io/shared/gets_ascii.rb
+++ b/spec/ruby/core/io/shared/gets_ascii.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 describe :io_gets_ascii, shared: true do
   describe "with ASCII separator" do
     before :each do
diff --git a/spec/ruby/core/io/shared/new.rb b/spec/ruby/core/io/shared/new.rb
index cc76955784..6f318ddee5 100644
--- a/spec/ruby/core/io/shared/new.rb
+++ b/spec/ruby/core/io/shared/new.rb
@@ -1,5 +1,7 @@
 require_relative '../fixtures/classes'
 
+# NOTE: should be synchronized with library/stringio/initialize_spec.rb
+
 # This group of specs may ONLY contain specs that do successfully create
 # an IO instance from the file descriptor returned by #new_fd helper.
 describe :io_new, shared: true do
@@ -18,48 +20,57 @@ describe :io_new, shared: true do
     rm_r @name
   end
 
-  it "creates an IO instance from a Fixnum argument" do
+  it "creates an IO instance from an Integer argument" do
     @io = IO.send(@method, @fd, "w")
-    @io.should be_an_instance_of(IO)
+    @io.should.instance_of?(IO)
   end
 
   it "creates an IO instance when STDOUT is closed" do
-    verbose, $VERBOSE = $VERBOSE, nil
-    stdout = STDOUT
-    stdout_file = tmp("stdout.txt")
-
-    begin
-      @io = IO.send(@method, @fd, "w")
-      @io.should be_an_instance_of(IO)
-    ensure
-      STDOUT = stdout
-      $VERBOSE = verbose
-      rm_r stdout_file
+    suppress_warning do
+      stdout = STDOUT
+      stdout_file = tmp("stdout.txt")
+
+      begin
+        @io = IO.send(@method, @fd, "w")
+        @io.should.instance_of?(IO)
+      ensure
+        STDOUT = stdout
+        rm_r stdout_file
+      end
     end
   end
 
   it "creates an IO instance when STDERR is closed" do
-    verbose, $VERBOSE = $VERBOSE, nil
-    stderr = STDERR
-    stderr_file = tmp("stderr.txt")
-    STDERR = new_io stderr_file
-    STDERR.close
-
-    begin
-      @io = IO.send(@method, @fd, "w")
-      @io.should be_an_instance_of(IO)
-    ensure
-      STDERR = stderr
-      $VERBOSE = verbose
-      rm_r stderr_file
+    suppress_warning do
+      stderr = STDERR
+      stderr_file = tmp("stderr.txt")
+      STDERR = new_io stderr_file
+      STDERR.close
+
+      begin
+        @io = IO.send(@method, @fd, "w")
+        @io.should.instance_of?(IO)
+      ensure
+        STDERR = stderr
+        rm_r stderr_file
+      end
     end
   end
 
-  it "calls #to_int on an object to convert to a Fixnum" do
+  it "calls #to_int on an object to convert to an Integer" do
     obj = mock("file descriptor")
     obj.should_receive(:to_int).and_return(@fd)
     @io = IO.send(@method, obj, "w")
-    @io.should be_an_instance_of(IO)
+    @io.should.instance_of?(IO)
+  end
+
+  it "accepts options as keyword arguments" do
+    @io = IO.send(@method, @fd, "w", flags: File::CREAT)
+    @io.write("foo").should == 3
+
+    -> {
+      IO.send(@method, @fd, "w", {flags: File::CREAT})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 3, expected 1..2)")
   end
 
   it "accepts a :mode option" do
@@ -148,22 +159,22 @@ describe :io_new, shared: true do
 
   it "sets binmode from mode string" do
     @io = IO.send(@method, @fd, 'wb')
-    @io.binmode?.should == true
+    @io.should.binmode?
   end
 
   it "does not set binmode without being asked" do
     @io = IO.send(@method, @fd, 'w')
-    @io.binmode?.should == false
+    @io.should_not.binmode?
   end
 
   it "sets binmode from :binmode option" do
     @io = IO.send(@method, @fd, 'w', binmode: true)
-    @io.binmode?.should == true
+    @io.should.binmode?
   end
 
   it "does not set binmode from false :binmode" do
     @io = IO.send(@method, @fd, 'w', binmode: false)
-    @io.binmode?.should == false
+    @io.should_not.binmode?
   end
 
   it "sets external encoding to binary with binmode in mode string" do
@@ -197,11 +208,30 @@ describe :io_new, shared: true do
     @io.internal_encoding.to_s.should == 'IBM866'
   end
 
-  it "accepts nil options" do
-    @io = suppress_keyword_warning do
+  it "does not use binary encoding when mode encoding is specified along with binmode: true option" do
+    @io = IO.send(@method, @fd, 'w:iso-8859-1', binmode: true)
+    @io.external_encoding.to_s.should == 'ISO-8859-1'
+  end
+
+  it "does not use textmode argument when mode encoding is specified" do
+    @io = IO.send(@method, @fd, 'w:ascii-8bit', textmode: true)
+    @io.external_encoding.to_s.should == 'ASCII-8BIT'
+  end
+
+  it "does not use binmode argument when external encoding is specified via the :external_encoding option" do
+    @io = IO.send(@method, @fd, 'w', binmode: true, external_encoding: 'iso-8859-1')
+    @io.external_encoding.to_s.should == 'ISO-8859-1'
+  end
+
+  it "does not use textmode argument when external encoding is specified via the :external_encoding option" do
+    @io = IO.send(@method, @fd, 'w', textmode: true, external_encoding: 'ascii-8bit')
+    @io.external_encoding.to_s.should == 'ASCII-8BIT'
+  end
+
+  it "raises ArgumentError for nil options" do
+    -> {
       IO.send(@method, @fd, 'w', nil)
-    end
-    @io.write("foo").should == 3
+    }.should.raise(ArgumentError)
   end
 
   it "coerces mode with #to_str" do
@@ -260,13 +290,13 @@ describe :io_new, shared: true do
 
   it "accepts an :autoclose option" do
     @io = IO.send(@method, @fd, 'w', autoclose: false)
-    @io.autoclose?.should == false
+    @io.should_not.autoclose?
     @io.autoclose = true
   end
 
   it "accepts any truthy option :autoclose" do
     @io = IO.send(@method, @fd, 'w', autoclose: 42)
-    @io.autoclose?.should == true
+    @io.should.autoclose?
   end
 end
 
@@ -284,99 +314,100 @@ describe :io_new_errors, shared: true do
   end
 
   it "raises an Errno::EBADF if the file descriptor is not valid" do
-    -> { IO.send(@method, -1, "w") }.should raise_error(Errno::EBADF)
+    -> { IO.send(@method, -1, "w") }.should.raise(Errno::EBADF)
   end
 
   it "raises an IOError if passed a closed stream" do
-    -> { IO.send(@method, IOSpecs.closed_io.fileno, 'w') }.should raise_error(IOError)
+    -> { IO.send(@method, IOSpecs.closed_io.fileno, 'w') }.should.raise(IOError)
   end
 
   platform_is_not :windows do
     it "raises an Errno::EINVAL if the new mode is not compatible with the descriptor's current mode" do
-      -> { IO.send(@method, @fd, "r") }.should raise_error(Errno::EINVAL)
+      -> { IO.send(@method, @fd, "r") }.should.raise(Errno::EINVAL)
     end
   end
 
   it "raises ArgumentError if passed an empty mode string" do
-    -> { IO.send(@method, @fd, "") }.should raise_error(ArgumentError)
+    -> { IO.send(@method, @fd, "") }.should.raise(ArgumentError)
   end
 
   it "raises an error if passed modes two ways" do
     -> {
       IO.send(@method, @fd, "w", mode: "w")
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if passed encodings two ways" do
     -> {
       @io = IO.send(@method, @fd, 'w:ISO-8859-1', encoding: 'ISO-8859-1')
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, 'w:ISO-8859-1', external_encoding: 'ISO-8859-1')
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
+    -> {
+      @io = IO.send(@method, @fd, 'w:ISO-8859-1', internal_encoding: 'ISO-8859-1')
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, 'w:ISO-8859-1:UTF-8', internal_encoding: 'ISO-8859-1')
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if passed matching binary/text mode two ways" do
     -> {
       @io = IO.send(@method, @fd, "wb", binmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, "wt", textmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       @io = IO.send(@method, @fd, "wb", textmode: false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, "wt", binmode: false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if passed conflicting binary/text mode two ways" do
     -> {
       @io = IO.send(@method, @fd, "wb", binmode: false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, "wt", textmode: false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       @io = IO.send(@method, @fd, "wb", textmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, "wt", binmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error when trying to set both binmode and textmode" do
     -> {
       @io = IO.send(@method, @fd, "w", textmode: true, binmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, File::Constants::WRONLY, textmode: true, binmode: true)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if not passed a hash or nil for options" do
     -> {
       @io = IO.send(@method, @fd, 'w', false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, false, false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @io = IO.send(@method, @fd, nil, false)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
-  it "raises TypeError if passed a hash for mode and nil for options" do
+  it "raises ArgumentError if passed a hash for mode and nil for options" do
     -> {
-      suppress_keyword_warning do
-        @io = IO.send(@method, @fd, {mode: 'w'}, nil)
-      end
-    }.should raise_error(TypeError)
+      @io = IO.send(@method, @fd, {mode: 'w'}, nil)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/io/shared/pos.rb b/spec/ruby/core/io/shared/pos.rb
index fb6d8087bc..f4d0405863 100644
--- a/spec/ruby/core/io/shared/pos.rb
+++ b/spec/ruby/core/io/shared/pos.rb
@@ -19,7 +19,7 @@ describe :io_pos, shared: true do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.send(@method) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send(@method) }.should.raise(IOError)
   end
 
   it "resets #eof?" do
@@ -27,7 +27,7 @@ describe :io_pos, shared: true do
       io.read 1
       io.read 1
       io.send(@method)
-      io.eof?.should == false
+      io.should_not.eof?
     end
   end
 end
@@ -60,13 +60,19 @@ describe :io_set_pos, shared: true do
     end
   end
 
-  it "does not accept Bignums that don't fit in a C long" do
+  it "raises TypeError when cannot convert implicitly argument to Integer" do
     File.open @fname do |io|
-      -> { io.send @method, 2**128 }.should raise_error(RangeError)
+      -> { io.send @method, Object.new }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+  end
+
+  it "does not accept Integers that don't fit in a C off_t" do
+    File.open @fname do |io|
+      -> { io.send @method, 2**128 }.should.raise(RangeError)
     end
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.send @method, 0 }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send @method, 0 }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/shared/readlines.rb b/spec/ruby/core/io/shared/readlines.rb
index de803f42e5..f54fccc2e3 100644
--- a/spec/ruby/core/io/shared/readlines.rb
+++ b/spec/ruby/core/io/shared/readlines.rb
@@ -1,11 +1,11 @@
 describe :io_readlines, shared: true do
   it "raises TypeError if the first parameter is nil" do
-    -> { IO.send(@method, nil, &@object) }.should raise_error(TypeError)
+    -> { IO.send(@method, nil, &@object) }.should.raise(TypeError)
   end
 
   it "raises an Errno::ENOENT if the file does not exist" do
     name = tmp("nonexistent.txt")
-    -> { IO.send(@method, name, &@object) }.should raise_error(Errno::ENOENT)
+    -> { IO.send(@method, name, &@object) }.should.raise(Errno::ENOENT)
   end
 
   it "yields a single string with entire content when the separator is nil" do
@@ -54,25 +54,40 @@ describe :io_readlines_options_19, shared: true do
       (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator
     end
 
-    describe "when the object is a Fixnum" do
+    describe "when the object is an Integer" do
       before :each do
         @sep = $/
       end
 
       after :each do
-        $/ = @sep
+        suppress_warning {$/ = @sep}
       end
 
       it "defaults to $/ as the separator" do
-        $/ = " "
+        suppress_warning {$/ = " "}
         result = IO.send(@method, @name, 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
 
-      it "uses the object as a limit if it is a Fixnum" do
+      it "uses the object as a limit if it is an Integer" do
         result = IO.send(@method, @name, 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_limit
       end
+
+      it "ignores the object as a limit if it is negative" do
+        result = IO.send(@method, @name, -2, &@object)
+        (result ? result : ScratchPad.recorded).should == IOSpecs.lines
+      end
+
+      it "does not accept Integers that don't fit in a C off_t" do
+        -> { IO.send(@method, @name, 2**128, &@object) }.should.raise(RangeError)
+      end
+
+      describe "when passed limit" do
+        it "raises ArgumentError when passed 0 as a limit" do
+          -> { IO.send(@method, @name, 0, &@object) }.should.raise(ArgumentError)
+        end
+      end
     end
 
     describe "when the object is a String" do
@@ -82,38 +97,40 @@ describe :io_readlines_options_19, shared: true do
       end
 
       it "accepts non-ASCII data as separator" do
-        result = IO.send(@method, @name, "\303\250".force_encoding("utf-8"), &@object)
+        result = IO.send(@method, @name, "\303\250".dup.force_encoding("utf-8"), &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_arbitrary_separator
       end
     end
 
-    describe "when the object is a Hash" do
-      it "uses the value as the options hash" do
-        result = IO.send(@method, @name, mode: "r", &@object)
-        (result ? result : ScratchPad.recorded).should == IOSpecs.lines
+    describe "when the object is an options Hash" do
+      it "raises TypeError exception" do
+        -> {
+          IO.send(@method, @name, { chomp: true }, &@object)
+        }.should.raise(TypeError)
       end
     end
-  end
 
-  describe "when passed name, object, object" do
-    describe "when the first object is a Fixnum" do
-      it "uses the second object as an options Hash" do
-        -> do
-          IO.send(@method, @filename, 10, mode: "w", &@object)
-        end.should raise_error(IOError)
-      end
+    describe "when the object is neither Integer nor String" do
+      it "raises TypeError exception" do
+        obj = mock("not io readlines limit")
 
-      it "calls #to_hash to convert the second object to a Hash" do
-        options = mock("io readlines options Hash")
-        options.should_receive(:to_hash).and_return({ mode: "w" })
-        -> do
-          IO.send(@method, @filename, 10, **options, &@object)
-        end.should raise_error(IOError)
+        -> {
+          IO.send(@method, @name, obj, &@object)
+        }.should.raise(TypeError)
       end
     end
+  end
 
+  describe "when passed name, keyword arguments" do
+    it "uses the keyword arguments as options" do
+      result = IO.send(@method, @name, mode: "r", &@object)
+      (result ? result : ScratchPad.recorded).should == IOSpecs.lines
+    end
+  end
+
+  describe "when passed name, object, object" do
     describe "when the first object is a String" do
-      it "uses the second object as a limit if it is a Fixnum" do
+      it "uses the second object as a limit if it is an Integer" do
         result = IO.send(@method, @name, " ", 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
@@ -124,32 +141,18 @@ describe :io_readlines_options_19, shared: true do
         result = IO.send(@method, @name, " ", limit, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
-
-      it "uses the second object as an options Hash" do
-        -> do
-          IO.send(@method, @filename, " ", mode: "w", &@object)
-        end.should raise_error(IOError)
-      end
-
-      it "calls #to_hash to convert the second object to a Hash" do
-        options = mock("io readlines options Hash")
-        options.should_receive(:to_hash).and_return({ mode: "w" })
-        -> do
-          IO.send(@method, @filename, " ", **options, &@object)
-        end.should raise_error(IOError)
-      end
     end
 
-    describe "when the first object is not a String or Fixnum" do
+    describe "when the first object is not a String or Integer" do
       it "calls #to_str to convert the object to a String" do
         sep = mock("io readlines separator")
         sep.should_receive(:to_str).at_least(1).and_return(" ")
-        result = IO.send(@method, @name, sep, 10, mode: "r", &@object)
+        result = IO.send(@method, @name, sep, 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
 
-      it "uses the second object as a limit if it is a Fixnum" do
-        result = IO.send(@method, @name, " ", 10, mode: "r", &@object)
+      it "uses the second object as a limit if it is an Integer" do
+        result = IO.send(@method, @name, " ", 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
 
@@ -159,24 +162,57 @@ describe :io_readlines_options_19, shared: true do
         result = IO.send(@method, @name, " ", limit, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
       end
+    end
+
+    describe "when the second object is neither Integer nor String" do
+      it "raises TypeError exception" do
+        obj = mock("not io readlines limit")
+
+        -> {
+          IO.send(@method, @name, " ", obj, &@object)
+        }.should.raise(TypeError)
+      end
+    end
 
-      it "uses the second object as an options Hash" do
+    describe "when the second object is an options Hash" do
+      it "raises TypeError exception" do
+        -> {
+          IO.send(@method, @name, "", { chomp: true }, &@object)
+        }.should.raise(TypeError)
+      end
+    end
+  end
+
+  describe "when passed name, object, keyword arguments" do
+    describe "when the first object is an Integer" do
+      it "uses the keyword arguments as options" do
+        -> do
+          IO.send(@method, @filename, 10, mode: "w", &@object)
+        end.should.raise(IOError)
+      end
+    end
+
+    describe "when the first object is a String" do
+      it "uses the keyword arguments as options" do
         -> do
           IO.send(@method, @filename, " ", mode: "w", &@object)
-        end.should raise_error(IOError)
+        end.should.raise(IOError)
       end
+    end
+
+    describe "when the first object is not a String or Integer" do
+      it "uses the keyword arguments as options" do
+        sep = mock("io readlines separator")
+        sep.should_receive(:to_str).at_least(1).and_return(" ")
 
-      it "calls #to_hash to convert the second object to a Hash" do
-        options = mock("io readlines options Hash")
-        options.should_receive(:to_hash).and_return({ mode: "w" })
         -> do
-          IO.send(@method, @filename, " ", **options, &@object)
-        end.should raise_error(IOError)
+          IO.send(@method, @filename, sep, mode: "w", &@object)
+        end.should.raise(IOError)
       end
     end
   end
 
-  describe "when passed name, separator, limit, options" do
+  describe "when passed name, separator, limit, keyword arguments" do
     it "calls #to_path to convert the name object" do
       name = mock("io name to_path")
       name.should_receive(:to_path).and_return(@name)
@@ -198,12 +234,24 @@ describe :io_readlines_options_19, shared: true do
       (result ? result : ScratchPad.recorded).should == IOSpecs.lines_space_separator_limit
     end
 
-    it "calls #to_hash to convert the options object" do
-      options = mock("io readlines options Hash")
-      options.should_receive(:to_hash).and_return({ mode: "w" })
+    it "uses the keyword arguments as options" do
       -> do
-        IO.send(@method, @filename, " ", 10, **options, &@object)
-      end.should raise_error(IOError)
+        IO.send(@method, @filename, " ", 10, mode: "w", &@object)
+      end.should.raise(IOError)
+    end
+
+    describe "when passed chomp, nil as a separator, and a limit" do
+      it "yields each line of limit size without truncating trailing new line character" do
+        # 43 - is a size of the 1st paragraph in the file
+        result = IO.send(@method, @name, nil, 43, chomp: true, &@object)
+
+        (result ? result : ScratchPad.recorded).should == [
+          "Voici la ligne une.\nQui è la linea due.\n\n\n",
+          "Aquí está la línea tres.\n" + "Hier ist Zeile ",
+          "vier.\n\nEstá aqui a linha cinco.\nHere is li",
+          "ne six.\n"
+        ]
+      end
     end
   end
 end
diff --git a/spec/ruby/core/io/shared/tty.rb b/spec/ruby/core/io/shared/tty.rb
index 89ac08ec86..1dc0e95739 100644
--- a/spec/ruby/core/io/shared/tty.rb
+++ b/spec/ruby/core/io/shared/tty.rb
@@ -19,6 +19,6 @@ describe :io_tty, shared: true do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.send @method }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.send @method }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/shared/write.rb b/spec/ruby/core/io/shared/write.rb
index 270b84ac39..5de9fe4335 100644
--- a/spec/ruby/core/io/shared/write.rb
+++ b/spec/ruby/core/io/shared/write.rb
@@ -23,7 +23,7 @@ describe :io_write, shared: true do
   end
 
   it "checks if the file is writable if writing more than zero bytes" do
-    -> { @readonly_file.send(@method, "abcde") }.should raise_error(IOError)
+    -> { @readonly_file.send(@method, "abcde") }.should.raise(IOError)
   end
 
   it "returns the number of bytes written" do
@@ -66,17 +66,7 @@ describe :io_write, shared: true do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.send(@method, "hello") }.should raise_error(IOError)
-  end
-
-  it "does not modify the passed argument" do
-    File.open(@filename, "w") do |f|
-      f.set_encoding(Encoding::IBM437)
-      # A character whose codepoint differs between UTF-8 and IBM437
-      f.write "ƒ".freeze
-    end
-
-    File.binread(@filename).bytes.should == [159]
+    -> { IOSpecs.closed_io.send(@method, "hello") }.should.raise(IOError)
   end
 
   describe "on a pipe" do
@@ -95,15 +85,70 @@ describe :io_write, shared: true do
       @r.read.should == "foo"
     end
 
-    # [ruby-core:90895] MJIT worker may leave fd open in a forked child.
-    # For instance, MJIT creates a worker before @r.close with fork(), @r.close happens,
-    # and the MJIT worker keeps the pipe open until the worker execve().
-    # TODO: consider acquiring GVL from MJIT worker.
-    guard_not -> { defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? } do
+    # [ruby-core:90895] RJIT worker may leave fd open in a forked child.
+    # For instance, RJIT creates a worker before @r.close with fork(), @r.close happens,
+    # and the RJIT worker keeps the pipe open until the worker execve().
+    # TODO: consider acquiring GVL from RJIT worker.
+    guard_not -> { defined?(RubyVM::RJIT) && RubyVM::RJIT.enabled? } do
       it "raises Errno::EPIPE if the read end is closed and does not die from SIGPIPE" do
         @r.close
-        -> { @w.send(@method, "foo") }.should raise_error(Errno::EPIPE, /Broken pipe/)
+        -> { @w.send(@method, "foo") }.should.raise(Errno::EPIPE, /Broken pipe/)
       end
     end
   end
 end
+
+describe :io_write_transcode, shared: true do
+  before :each do
+    @transcode_filename = tmp("io_write_transcode")
+  end
+
+  after :each do
+    rm_r @transcode_filename
+  end
+
+  it "transcodes the given string when the external encoding is set and neither is BINARY" do
+    utf8_str = "hello"
+
+    File.open(@transcode_filename, "w", external_encoding: Encoding::UTF_16BE) do |file|
+      file.external_encoding.should == Encoding::UTF_16BE
+      file.send(@method, utf8_str)
+    end
+
+    result = File.binread(@transcode_filename)
+    expected = [0, 104, 0, 101, 0, 108, 0, 108, 0, 111] # UTF-16BE bytes for "hello"
+
+    result.bytes.should == expected
+  end
+
+  it "transcodes the given string when the external encoding is set and the string encoding is BINARY" do
+    str = "été".b
+
+    File.open(@transcode_filename, "w", external_encoding: Encoding::UTF_16BE) do |file|
+      file.external_encoding.should == Encoding::UTF_16BE
+      -> { file.send(@method, str) }.should.raise(Encoding::UndefinedConversionError)
+    end
+  end
+end
+
+describe :io_write_no_transcode, shared: true do
+  before :each do
+    @transcode_filename = tmp("io_write_no_transcode")
+  end
+
+  after :each do
+    rm_r @transcode_filename
+  end
+
+  it "does not transcode the given string even when the external encoding is set" do
+    utf8_str = "hello"
+
+    File.open(@transcode_filename, "w", external_encoding: Encoding::UTF_16BE) do |file|
+      file.external_encoding.should == Encoding::UTF_16BE
+      file.send(@method, utf8_str)
+    end
+
+    result = File.binread(@transcode_filename)
+    result.bytes.should == utf8_str.bytes
+  end
+end
diff --git a/spec/ruby/core/io/stat_spec.rb b/spec/ruby/core/io/stat_spec.rb
index 58eba02b8f..f9fc232ee0 100644
--- a/spec/ruby/core/io/stat_spec.rb
+++ b/spec/ruby/core/io/stat_spec.rb
@@ -3,7 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "IO#stat" do
   before :each do
-    @io = IO.popen 'cat', "r+"
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, "r+"
   end
 
   after :each do
@@ -11,14 +12,14 @@ describe "IO#stat" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.stat }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.stat }.should.raise(IOError)
   end
 
   it "returns a File::Stat object for the stream" do
-    STDOUT.stat.should be_an_instance_of(File::Stat)
+    STDOUT.stat.should.instance_of?(File::Stat)
   end
 
   it "can stat pipes" do
-    @io.stat.should be_an_instance_of(File::Stat)
+    @io.stat.should.instance_of?(File::Stat)
   end
 end
diff --git a/spec/ruby/core/io/sync_spec.rb b/spec/ruby/core/io/sync_spec.rb
index 993b7ee244..b537db335b 100644
--- a/spec/ruby/core/io/sync_spec.rb
+++ b/spec/ruby/core/io/sync_spec.rb
@@ -27,7 +27,7 @@ describe "IO#sync=" do
   end
 
   it "raises an IOError on closed stream" do
-    -> { IOSpecs.closed_io.sync = true }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.sync = true }.should.raise(IOError)
   end
 end
 
@@ -45,7 +45,7 @@ describe "IO#sync" do
   end
 
   it "raises an IOError on closed stream" do
-    -> { IOSpecs.closed_io.sync }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.sync }.should.raise(IOError)
   end
 end
 
diff --git a/spec/ruby/core/io/sysopen_spec.rb b/spec/ruby/core/io/sysopen_spec.rb
index 4607d13687..325d51ed23 100644
--- a/spec/ruby/core/io/sysopen_spec.rb
+++ b/spec/ruby/core/io/sysopen_spec.rb
@@ -13,16 +13,16 @@ describe "IO.sysopen" do
 
   it "returns the file descriptor for a given path" do
     @fd = IO.sysopen(@filename, "w")
-    @fd.should be_kind_of(Fixnum)
-    @fd.should_not equal(0)
+    @fd.should.is_a?(Integer)
+    @fd.should_not.equal?(0)
   end
 
   # opening a directory is not supported on Windows
   platform_is_not :windows do
     it "works on directories" do
       @fd = IO.sysopen(tmp(""))    # /tmp
-      @fd.should be_kind_of(Fixnum)
-      @fd.should_not equal(0)
+      @fd.should.is_a?(Integer)
+      @fd.should_not.equal?(0)
     end
   end
 
@@ -33,18 +33,18 @@ describe "IO.sysopen" do
   end
 
   it "accepts a mode as second argument" do
-    -> { @fd = IO.sysopen(@filename, "w") }.should_not raise_error
-    @fd.should_not equal(0)
+    -> { @fd = IO.sysopen(@filename, "w") }.should_not.raise
+    @fd.should_not.equal?(0)
   end
 
   it "accepts permissions as third argument" do
     @fd = IO.sysopen(@filename, "w", 777)
-    @fd.should_not equal(0)
+    @fd.should_not.equal?(0)
   end
 
   it "accepts mode & permission that are nil" do
     touch @filename # create the file
     @fd = IO.sysopen(@filename, nil, nil)
-    @fd.should_not equal(0)
+    @fd.should_not.equal?(0)
   end
 end
diff --git a/spec/ruby/core/io/sysread_spec.rb b/spec/ruby/core/io/sysread_spec.rb
index 024200efea..2d58db2250 100644
--- a/spec/ruby/core/io/sysread_spec.rb
+++ b/spec/ruby/core/io/sysread_spec.rb
@@ -6,7 +6,7 @@ describe "IO#sysread on a file" do
     @file_name = tmp("IO_sysread_file") + $$.to_s
     File.open(@file_name, "w") do |f|
       # write some stuff
-      f.write("012345678901234567890123456789")
+      f.write("012345678901234567890123456789\nabcdef")
     end
     @file = File.open(@file_name, "r+")
   end
@@ -21,25 +21,25 @@ describe "IO#sysread on a file" do
   end
 
   it "reads the specified number of bytes from the file to the buffer" do
-    buf = "" # empty buffer
+    buf = +"" # empty buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
 
     @file.rewind
 
-    buf = "ABCDE" # small buffer
+    buf = +"ABCDE" # small buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
 
     @file.rewind
 
-    buf = "ABCDE" * 5 # large buffer
+    buf = +"ABCDE" * 5 # large buffer
     @file.sysread(15, buf).should == buf
     buf.should == "012345678901234"
   end
 
   it "coerces the second argument to string and uses it as a buffer" do
-    buf = "ABCDE"
+    buf = +"ABCDE"
     (obj = mock("buff")).should_receive(:to_str).any_number_of_times.and_return(buf)
     @file.sysread(15, obj).should == buf
     buf.should == "012345678901234"
@@ -50,6 +50,11 @@ describe "IO#sysread on a file" do
     @file.sysread(5).should == "56789"
   end
 
+  it "raises an error when called after buffered reads" do
+    @file.readline
+    -> { @file.sysread(5) }.should.raise(IOError)
+  end
+
   it "reads normally even when called immediately after a buffered IO#read" do
     @file.read(15)
     @file.sysread(5).should == "56789"
@@ -58,13 +63,13 @@ describe "IO#sysread on a file" do
   it "does not raise error if called after IO#read followed by IO#write" do
     @file.read(5)
     @file.write("abcde")
-    -> { @file.sysread(5) }.should_not raise_error(IOError)
+    -> { @file.sysread(5) }.should_not.raise(IOError)
   end
 
   it "does not raise error if called after IO#read followed by IO#syswrite" do
     @file.read(5)
     @file.syswrite("abcde")
-    -> { @file.sysread(5) }.should_not raise_error(IOError)
+    -> { @file.sysread(5) }.should_not.raise(IOError)
   end
 
   it "reads updated content after the flushed buffered IO#write" do
@@ -77,7 +82,37 @@ describe "IO#sysread on a file" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.sysread(5) }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.sysread(5) }.should.raise(IOError)
+  end
+
+  it "immediately returns an empty string if the length argument is 0" do
+    @file.sysread(0).should == ""
+  end
+
+  it "immediately returns the given buffer if the length argument is 0" do
+    buffer = +"existing content"
+    @file.sysread(0, buffer).should == buffer
+    buffer.should == "existing content"
+  end
+
+  it "discards the existing buffer content upon successful read" do
+    buffer = +"existing content"
+    @file.sysread(11, buffer).should.equal?(buffer)
+    buffer.should == "01234567890"
+  end
+
+  it "discards the existing buffer content upon error" do
+    buffer = +"existing content"
+    @file.seek(0, :END)
+    -> { @file.sysread(1, buffer) }.should.raise(EOFError)
+    buffer.should.empty?
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    string = @file.sysread(10, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
   end
 end
 
@@ -95,4 +130,8 @@ describe "IO#sysread" do
     @write.syswrite "ab"
     @read.sysread(3).should == "ab"
   end
+
+  it "raises ArgumentError when length is less than 0" do
+    -> { @read.sysread(-1) }.should.raise(ArgumentError)
+  end
 end
diff --git a/spec/ruby/core/io/sysseek_spec.rb b/spec/ruby/core/io/sysseek_spec.rb
index df894734e3..2384895dc5 100644
--- a/spec/ruby/core/io/sysseek_spec.rb
+++ b/spec/ruby/core/io/sysseek_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 require_relative 'shared/pos'
 
 describe "IO#sysseek" do
-  it_behaves_like :io_set_pos, :seek
+  it_behaves_like :io_set_pos, :sysseek
 end
 
 describe "IO#sysseek" do
@@ -23,7 +23,12 @@ describe "IO#sysseek" do
 
   it "raises an error when called after buffered reads" do
     @io.readline
-    -> { @io.sysseek(-5, IO::SEEK_CUR) }.should raise_error(IOError)
+    -> { @io.sysseek(-5, IO::SEEK_CUR) }.should.raise(IOError)
+  end
+
+  it "seeks normally even when called immediately after a buffered IO#read" do
+    @io.read(15)
+    @io.sysseek(-5, IO::SEEK_CUR).should == 10
   end
 
   it "moves the read position relative to the start with SEEK_SET" do
@@ -36,7 +41,7 @@ describe "IO#sysseek" do
 
     # this is the safest way of checking the EOF when
     # sys-* methods are invoked
-    -> { @io.sysread(1) }.should raise_error(EOFError)
+    -> { @io.sysread(1) }.should.raise(EOFError)
 
     @io.sysseek(-25, IO::SEEK_END)
     @io.sysread(7).should == "cinco.\n"
diff --git a/spec/ruby/core/io/syswrite_spec.rb b/spec/ruby/core/io/syswrite_spec.rb
index a28cc62174..8bf61a27c3 100644
--- a/spec/ruby/core/io/syswrite_spec.rb
+++ b/spec/ruby/core/io/syswrite_spec.rb
@@ -29,6 +29,16 @@ describe "IO#syswrite on a file" do
     end
   end
 
+  it "does not modify the passed argument" do
+    File.open(@filename, "w") do |f|
+      f.set_encoding(Encoding::IBM437)
+      # A character whose codepoint differs between UTF-8 and IBM437
+      f.syswrite("ƒ".freeze)
+    end
+
+    File.binread(@filename).bytes.should == [198, 146]
+  end
+
   it "warns if called immediately after a buffered IO#write" do
     @file.write("abcde")
     -> { @file.syswrite("fghij") }.should complain(/syswrite/)
@@ -68,4 +78,5 @@ end
 
 describe "IO#syswrite" do
   it_behaves_like :io_write, :syswrite
+  it_behaves_like :io_write_no_transcode, :syswrite
 end
diff --git a/spec/ruby/core/io/to_i_spec.rb b/spec/ruby/core/io/to_i_spec.rb
index acf138c663..1d0cf2a1f6 100644
--- a/spec/ruby/core/io/to_i_spec.rb
+++ b/spec/ruby/core/io/to_i_spec.rb
@@ -7,6 +7,6 @@ describe "IO#to_i" do
   end
 
   it "raises IOError on closed stream" do
-    -> { IOSpecs.closed_io.to_i }.should raise_error(IOError)
+    -> { IOSpecs.closed_io.to_i }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/to_io_spec.rb b/spec/ruby/core/io/to_io_spec.rb
index 55a0977740..0b1809dffa 100644
--- a/spec/ruby/core/io/to_io_spec.rb
+++ b/spec/ruby/core/io/to_io_spec.rb
@@ -11,11 +11,11 @@ describe "IO#to_io" do
   end
 
   it "returns self for open stream" do
-    @io.to_io.should equal(@io)
+    @io.to_io.should.equal?(@io)
   end
 
   it "returns self for closed stream" do
     io = IOSpecs.closed_io
-    io.to_io.should equal(io)
+    io.to_io.should.equal?(io)
   end
 end
diff --git a/spec/ruby/core/io/try_convert_spec.rb b/spec/ruby/core/io/try_convert_spec.rb
index 5fbd10b6fa..7600b01b75 100644
--- a/spec/ruby/core/io/try_convert_spec.rb
+++ b/spec/ruby/core/io/try_convert_spec.rb
@@ -13,7 +13,7 @@ describe "IO.try_convert" do
   end
 
   it "returns the passed IO object" do
-    IO.try_convert(@io).should equal(@io)
+    IO.try_convert(@io).should.equal?(@io)
   end
 
   it "does not call #to_io on an IO instance" do
@@ -24,26 +24,26 @@ describe "IO.try_convert" do
   it "calls #to_io to coerce an object" do
     obj = mock("io")
     obj.should_receive(:to_io).and_return(@io)
-    IO.try_convert(obj).should equal(@io)
+    IO.try_convert(obj).should.equal?(@io)
   end
 
   it "returns nil when the passed object does not respond to #to_io" do
-    IO.try_convert(mock("io")).should be_nil
+    IO.try_convert(mock("io")).should == nil
   end
 
   it "return nil when BasicObject is passed" do
-    IO.try_convert(BasicObject.new).should be_nil
+    IO.try_convert(BasicObject.new).should == nil
   end
 
   it "raises a TypeError if the object does not return an IO from #to_io" do
     obj = mock("io")
     obj.should_receive(:to_io).and_return("io")
-    -> { IO.try_convert(obj) }.should raise_error(TypeError)
+    -> { IO.try_convert(obj) }.should raise_consistent_error(TypeError, "can't convert MockObject into IO (MockObject#to_io gives String)")
   end
 
   it "propagates an exception raised by #to_io" do
     obj = mock("io")
     obj.should_receive(:to_io).and_raise(TypeError.new)
-    ->{ IO.try_convert(obj) }.should raise_error(TypeError)
+    ->{ IO.try_convert(obj) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/io/ungetbyte_spec.rb b/spec/ruby/core/io/ungetbyte_spec.rb
index 1971dee534..e0615cd76c 100644
--- a/spec/ruby/core/io/ungetbyte_spec.rb
+++ b/spec/ruby/core/io/ungetbyte_spec.rb
@@ -13,12 +13,12 @@ describe "IO#ungetbyte" do
   end
 
   it "does nothing when passed nil" do
-    @io.ungetbyte(nil).should be_nil
+    @io.ungetbyte(nil).should == nil
     @io.getbyte.should == 97
   end
 
   it "puts back each byte in a String argument" do
-    @io.ungetbyte("cat").should be_nil
+    @io.ungetbyte("cat").should == nil
     @io.getbyte.should == 99
     @io.getbyte.should == 97
     @io.getbyte.should == 116
@@ -29,45 +29,26 @@ describe "IO#ungetbyte" do
     str = mock("io ungetbyte")
     str.should_receive(:to_str).and_return("dog")
 
-    @io.ungetbyte(str).should be_nil
+    @io.ungetbyte(str).should == nil
     @io.getbyte.should == 100
     @io.getbyte.should == 111
     @io.getbyte.should == 103
     @io.getbyte.should == 97
   end
 
-  ruby_version_is ''...'2.6' do
-    it "puts back one byte for a Fixnum argument..." do
-      @io.ungetbyte(4095).should be_nil
+  it "never raises RangeError" do
+    for i in [4095, 0x4f7574206f6620636861722072616e67ff] do
+      @io.ungetbyte(i).should == nil
       @io.getbyte.should == 255
     end
-
-    it "... but not for Bignum argument (eh?)" do
-      -> {
-        @io.ungetbyte(0x4f7574206f6620636861722072616e6765)
-      }.should raise_error(TypeError)
-    end
-  end
-
-  ruby_version_is '2.6'...'2.6.1' do
-    it "is an RangeError if the integer is not in 8bit" do
-      for i in [4095, 0x4f7574206f6620636861722072616e6765] do
-        -> { @io.ungetbyte(i) }.should raise_error(RangeError)
-      end
-    end
   end
 
-  ruby_version_is '2.6.1' do
-    it "never raises RangeError" do
-      for i in [4095, 0x4f7574206f6620636861722072616e67ff] do
-        @io.ungetbyte(i).should be_nil
-        @io.getbyte.should == 255
-      end
-    end
+  it "raises IOError on stream not opened for reading" do
+    -> { STDOUT.ungetbyte(42) }.should.raise(IOError, "not opened for reading")
   end
 
   it "raises an IOError if the IO is closed" do
     @io.close
-    -> { @io.ungetbyte(42) }.should raise_error(IOError)
+    -> { @io.ungetbyte(42) }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/ungetc_spec.rb b/spec/ruby/core/io/ungetc_spec.rb
index 34d4caf745..4a9e67f126 100644
--- a/spec/ruby/core/io/ungetc_spec.rb
+++ b/spec/ruby/core/io/ungetc_spec.rb
@@ -74,10 +74,10 @@ describe "IO#ungetc" do
     touch(@empty)
 
     File.open(@empty) { |empty|
-      empty.eof?.should == true
+      empty.should.eof?
       empty.getc.should == nil
       empty.ungetc(100)
-      empty.eof?.should == false
+      empty.should_not.eof?
     }
   end
 
@@ -100,18 +100,17 @@ describe "IO#ungetc" do
   it "makes subsequent unbuffered operations to raise IOError" do
     @io.getc
     @io.ungetc(100)
-    -> { @io.sysread(1) }.should raise_error(IOError)
+    -> { @io.sysread(1) }.should.raise(IOError)
   end
 
-  it "does not affect the stream and returns nil when passed nil" do
+  it "raises TypeError if passed nil" do
     @io.getc.should == ?V
-    @io.ungetc(nil)
-    @io.getc.should == ?o
+    proc{@io.ungetc(nil)}.should.raise(TypeError)
   end
 
   it "puts one or more characters back in the stream" do
     @io.gets
-    @io.ungetc("Aquí ").should be_nil
+    @io.ungetc("Aquí ").should == nil
     @io.gets.chomp.should == "Aquí Qui è la linea due."
   end
 
@@ -119,17 +118,21 @@ describe "IO#ungetc" do
     chars = mock("io ungetc")
     chars.should_receive(:to_str).and_return("Aquí ")
 
-    @io.ungetc(chars).should be_nil
+    @io.ungetc(chars).should == nil
     @io.gets.chomp.should == "Aquí Voici la ligne une."
   end
 
   it "returns nil when invoked on stream that was not yet read" do
-    @io.ungetc(100).should be_nil
+    @io.ungetc(100).should == nil
+  end
+
+  it "raises IOError on stream not opened for reading" do
+    -> { STDOUT.ungetc(100) }.should.raise(IOError, "not opened for reading")
   end
 
   it "raises IOError on closed stream" do
     @io.getc
     @io.close
-    -> { @io.ungetc(100) }.should raise_error(IOError)
+    -> { @io.ungetc(100) }.should.raise(IOError)
   end
 end
diff --git a/spec/ruby/core/io/write_nonblock_spec.rb b/spec/ruby/core/io/write_nonblock_spec.rb
index 5474e5c6ce..a6bd43c058 100644
--- a/spec/ruby/core/io/write_nonblock_spec.rb
+++ b/spec/ruby/core/io/write_nonblock_spec.rb
@@ -31,15 +31,26 @@ platform_is_not :windows do
       end
     end
 
+    it "does not modify the passed argument" do
+      File.open(@filename, "w") do |f|
+        f.set_encoding(Encoding::IBM437)
+        # A character whose codepoint differs between UTF-8 and IBM437
+        f.write_nonblock("ƒ".freeze)
+      end
+
+      File.binread(@filename).bytes.should == [198, 146]
+    end
+
     it "checks if the file is writable if writing zero bytes" do
       -> {
-         @readonly_file.write_nonblock("")
-      }.should raise_error(IOError)
+        @readonly_file.write_nonblock("")
+      }.should.raise(IOError)
     end
   end
 
   describe "IO#write_nonblock" do
     it_behaves_like :io_write, :write_nonblock
+    it_behaves_like :io_write_no_transcode, :write_nonblock
   end
 end
 
@@ -56,12 +67,12 @@ describe 'IO#write_nonblock' do
   it "raises an exception extending IO::WaitWritable when the write would block" do
     -> {
       loop { @write.write_nonblock('a' * 10_000) }
-    }.should raise_error(IO::WaitWritable) { |e|
+    }.should.raise(IO::WaitWritable) { |e|
       platform_is_not :windows do
-        e.should be_kind_of(Errno::EAGAIN)
+        e.should.is_a?(Errno::EAGAIN)
       end
       platform_is :windows do
-        e.should be_kind_of(Errno::EWOULDBLOCK)
+        e.should.is_a?(Errno::EWOULDBLOCK)
       end
     }
   end
@@ -79,7 +90,7 @@ describe 'IO#write_nonblock' do
     it 'sets the IO in nonblock mode' do
       require 'io/nonblock'
       @write.write_nonblock('a')
-      @write.nonblock?.should == true
+      @write.should.nonblock?
     end
   end
 end
diff --git a/spec/ruby/core/io/write_spec.rb b/spec/ruby/core/io/write_spec.rb
index b28b582019..1a745ba012 100644
--- a/spec/ruby/core/io/write_spec.rb
+++ b/spec/ruby/core/io/write_spec.rb
@@ -21,11 +21,7 @@ describe "IO#write on a file" do
   end
 
   it "does not check if the file is writable if writing zero bytes" do
-    -> { @readonly_file.write("") }.should_not raise_error
-  end
-
-  it "returns a length of 0 when writing a blank string" do
-    @file.write('').should == 0
+    -> { @readonly_file.write("") }.should_not.raise
   end
 
   before :each do
@@ -40,10 +36,44 @@ describe "IO#write on a file" do
     Encoding.default_internal = @internal
   end
 
+  it "returns a length of 0 when writing a blank string" do
+    @file.write('').should == 0
+  end
+
+  it "returns a length of 0 when writing blank strings" do
+    @file.write('', '', '').should == 0
+  end
+
+  it "returns a length of 0 when passed no arguments" do
+    @file.write().should == 0
+  end
+
   it "returns the number of bytes written" do
     @file.write("hellø").should == 6
   end
 
+  it "does not modify the passed argument" do
+    File.open(@filename, "w") do |f|
+      f.set_encoding(Encoding::IBM437)
+      # A character whose codepoint differs between UTF-8 and IBM437
+      f.write("ƒ".freeze)
+    end
+
+    File.binread(@filename).bytes.should == [159]
+  end
+
+  it "does not modify arguments when passed multiple arguments and external encoding not set" do
+    a, b = "a".freeze, "b".freeze
+
+    File.open(@filename, "w") do |f|
+      f.write(a, b)
+    end
+
+    File.binread(@filename).bytes.should == [97, 98]
+    a.encoding.should == Encoding::UTF_8
+    b.encoding.should == Encoding::UTF_8
+  end
+
   it "uses the encoding from the given option for non-ascii encoding" do
     File.open(@filename, "w", encoding: Encoding::UTF_32LE) do |file|
       file.write("hi").should == 8
@@ -51,15 +81,39 @@ describe "IO#write on a file" do
     File.binread(@filename).should == "h\u0000\u0000\u0000i\u0000\u0000\u0000"
   end
 
-  it "uses an :open_args option" do
-    IO.write(@filename, 'hi', open_args: ["w", nil, {encoding: Encoding::UTF_32LE}]).should == 8
+  it "uses the encoding from the given option for non-ascii encoding even if in binary mode" do
+    File.open(@filename, "w", encoding: Encoding::UTF_32LE, binmode: true) do |file|
+      file.should.binmode?
+      file.write("hi").should == 8
+    end
+    File.binread(@filename).should == "h\u0000\u0000\u0000i\u0000\u0000\u0000"
+
+    File.open(@filename, "wb", encoding: Encoding::UTF_32LE) do |file|
+      file.should.binmode?
+      file.write("hi").should == 8
+    end
+    File.binread(@filename).should == "h\u0000\u0000\u0000i\u0000\u0000\u0000"
+  end
+
+  it "uses the encoding from the given option for non-ascii encoding when multiple arguments passes" do
+    File.open(@filename, "w", encoding: Encoding::UTF_32LE) do |file|
+      file.write("h", "i").should == 8
+    end
+    File.binread(@filename).should == "h\u0000\u0000\u0000i\u0000\u0000\u0000"
+  end
+
+  it "ignores the 'bom|' prefix" do
+    File.open(@filename, "w", encoding: 'bom|utf-8') do |file|
+      file.write("hi")
+    end
+    File.binread(@filename).should == "hi"
   end
 
   it "raises a invalid byte sequence error if invalid bytes are being written" do
     # pack "\xFEhi" to avoid utf-8 conflict
     xFEhi = ([254].pack('C*') + 'hi').force_encoding('utf-8')
     File.open(@filename, "w", encoding: Encoding::US_ASCII) do |file|
-      -> { file.write(xFEhi) }.should raise_error(Encoding::InvalidByteSequenceError)
+      -> { file.write(xFEhi) }.should.raise(Encoding::InvalidByteSequenceError)
     end
   end
 
@@ -72,6 +126,20 @@ describe "IO#write on a file" do
     res = "H#{ë}ll#{ö}"
     File.binread(@filename).should == res.force_encoding(Encoding::BINARY)
   end
+
+  platform_is_not :windows do
+    it "writes binary data if no encoding is given and multiple arguments passed" do
+      File.open(@filename, "w") do |file|
+        file.write("\x87".b, "ą") # 0x87 isn't a valid UTF-8 binary representation of a character
+      end
+      File.binread(@filename).bytes.should == [0x87, 0xC4, 0x85]
+
+      File.open(@filename, "w") do |file|
+        file.write("\x61".encode("utf-32le"), "ą")
+      end
+      File.binread(@filename).bytes.should == [0x61, 0x00, 0x00, 0x00, 0xC4, 0x85]
+    end
+  end
 end
 
 describe "IO.write" do
@@ -86,10 +154,44 @@ describe "IO.write" do
     File.read(@filename).should == "\0\0hi"
   end
 
+  it "requires mode to be specified in :open_args" do
+    -> {
+      IO.write(@filename, 'hi', open_args: [{encoding: Encoding::UTF_32LE, binmode: true}])
+    }.should.raise(IOError, "not opened for writing")
+
+    IO.write(@filename, 'hi', open_args: ["w", {encoding: Encoding::UTF_32LE, binmode: true}]).should == 8
+    IO.write(@filename, 'hi', open_args: [{encoding: Encoding::UTF_32LE, binmode: true, mode: "w"}]).should == 8
+  end
+
+  it "requires mode to be specified in :open_args even if flags option passed" do
+    -> {
+      IO.write(@filename, 'hi', open_args: [{encoding: Encoding::UTF_32LE, binmode: true, flags: File::CREAT}])
+    }.should.raise(IOError, "not opened for writing")
+
+    IO.write(@filename, 'hi', open_args: ["w", {encoding: Encoding::UTF_32LE, binmode: true, flags: File::CREAT}]).should == 8
+    IO.write(@filename, 'hi', open_args: [{encoding: Encoding::UTF_32LE, binmode: true, flags: File::CREAT, mode: "w"}]).should == 8
+  end
+
   it "uses the given encoding and returns the number of bytes written" do
     IO.write(@filename, 'hi', mode: "w", encoding: Encoding::UTF_32LE).should == 8
   end
 
+  it "raises ArgumentError if encoding is specified in mode parameter and is given as :encoding option" do
+    -> {
+      IO.write(@filename, 'hi', mode: "w:UTF-16LE:UTF-16BE", encoding: Encoding::UTF_32LE)
+    }.should.raise(ArgumentError, "encoding specified twice")
+
+    -> {
+      IO.write(@filename, 'hi', mode: "w:UTF-16BE", encoding: Encoding::UTF_32LE)
+    }.should.raise(ArgumentError, "encoding specified twice")
+  end
+
+  it "writes the file with the permissions in the :perm parameter" do
+    rm_r @filename
+    IO.write(@filename, 'write :perm spec', mode: "w", perm: 0o755).should == 16
+    (File.stat(@filename).mode & 0o777) == 0o755
+  end
+
   it "writes binary data if no encoding is given" do
     IO.write(@filename, 'Hëllö'.encode('ISO-8859-1'))
     xEB = [235].pack('C*')
@@ -108,32 +210,46 @@ describe "IO.write" do
         rm_r @fifo
       end
 
-      it "writes correctly" do
-        thr = Thread.new do
-          IO.read(@fifo)
-        end
-        begin
-          string = "hi"
-          IO.write(@fifo, string).should == string.length
-        ensure
-          thr.join
+      # rb_cloexec_open() is currently missing a retry on EINTR.
+      # @ioquatix is looking into fixing it. Quarantined until it's done.
+      quarantine! do
+        it "writes correctly" do
+          thr = Thread.new do
+            IO.read(@fifo)
+          end
+          begin
+            string = "hi"
+            IO.write(@fifo, string).should == string.length
+          ensure
+            thr.join
+          end
         end
       end
     end
+
+    ruby_version_is ""..."4.0" do
+      # https://bugs.ruby-lang.org/issues/19630
+      it "warns about deprecation given a path with a pipe" do
+        -> {
+          -> {
+            IO.write("|cat", "xxx")
+          }.should output_to_fd("xxx")
+        }.should complain(/IO process creation with a leading '\|'/)
+      end
+    end
   end
 end
 
 describe "IO#write" do
   it_behaves_like :io_write, :write
+  it_behaves_like :io_write_transcode, :write
 
-  ruby_version_is "2.5" do
-    it "accepts multiple arguments" do
-      IO.pipe do |r, w|
-        w.write("foo", "bar")
-        w.close
+  it "accepts multiple arguments" do
+    IO.pipe do |r, w|
+      w.write("foo", "bar")
+      w.close
 
-        r.read.should == "foobar"
-      end
+      r.read.should == "foobar"
     end
   end
 end
@@ -164,3 +280,25 @@ platform_is :windows do
     end
   end
 end
+
+describe "IO#write on STDOUT" do
+  # https://bugs.ruby-lang.org/issues/14413
+  platform_is_not :windows do
+    it "raises SignalException SIGPIPE if the stream is closed instead of Errno::EPIPE like other IOs" do
+      stderr_file = tmp("stderr")
+      begin
+        IO.popen([*ruby_exe, "-e", "loop { puts :ok }"], "r", err: stderr_file) do |io|
+          io.gets.should == "ok\n"
+          io.close
+        end
+        status = $?
+        status.should_not.success?
+        status.should.signaled?
+        Signal.signame(status.termsig).should == 'PIPE'
+        File.read(stderr_file).should.empty?
+      ensure
+        rm_r stderr_file
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/kernel/Array_spec.rb b/spec/ruby/core/kernel/Array_spec.rb
index b4a8bb7599..063faf7097 100644
--- a/spec/ruby/core/kernel/Array_spec.rb
+++ b/spec/ruby/core/kernel/Array_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel" do
   it "has private instance method Array()" do
-    Kernel.should have_private_instance_method(:Array)
+    Kernel.private_instance_methods(false).should.include?(:Array)
   end
 end
 
@@ -77,14 +77,14 @@ describe :kernel_Array, shared: true do
     obj = mock("Array() string")
     obj.should_receive(:to_ary).and_return("string")
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_a does not return an Array" do
     obj = mock("Array() string")
     obj.should_receive(:to_a).and_return("string")
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 end
 
diff --git a/spec/ruby/core/kernel/Complex_spec.rb b/spec/ruby/core/kernel/Complex_spec.rb
index 37f9843931..92ce183cc8 100644
--- a/spec/ruby/core/kernel/Complex_spec.rb
+++ b/spec/ruby/core/kernel/Complex_spec.rb
@@ -1,4 +1,6 @@
 require_relative '../../spec_helper'
+require_relative '../../shared/kernel/complex'
+require_relative 'fixtures/Complex'
 
 describe "Kernel.Complex()" do
   describe "when passed [Complex, Complex]" do
@@ -17,19 +19,19 @@ describe "Kernel.Complex()" do
 
   describe "when passed [Integer, Integer]" do
     it "returns a new Complex number" do
-      Complex(1, 2).should be_an_instance_of(Complex)
+      Complex(1, 2).should.instance_of?(Complex)
       Complex(1, 2).real.should == 1
       Complex(1, 2).imag.should == 2
 
-      Complex(-3, -5).should be_an_instance_of(Complex)
+      Complex(-3, -5).should.instance_of?(Complex)
       Complex(-3, -5).real.should == -3
       Complex(-3, -5).imag.should == -5
 
-      Complex(3.5, -4.5).should be_an_instance_of(Complex)
+      Complex(3.5, -4.5).should.instance_of?(Complex)
       Complex(3.5, -4.5).real.should == 3.5
       Complex(3.5, -4.5).imag.should == -4.5
 
-      Complex(bignum_value, 30).should be_an_instance_of(Complex)
+      Complex(bignum_value, 30).should.instance_of?(Complex)
       Complex(bignum_value, 30).real.should == bignum_value
       Complex(bignum_value, 30).imag.should == 30
     end
@@ -39,26 +41,111 @@ describe "Kernel.Complex()" do
     it "returns a new Complex number with 0 as the imaginary component" do
       # Guard against the Mathn library
       guard -> { !defined?(Math.rsqrt) } do
-        Complex(1).should be_an_instance_of(Complex)
+        Complex(1).should.instance_of?(Complex)
         Complex(1).imag.should == 0
         Complex(1).real.should == 1
 
-        Complex(-3).should be_an_instance_of(Complex)
+        Complex(-3).should.instance_of?(Complex)
         Complex(-3).imag.should == 0
         Complex(-3).real.should == -3
 
-        Complex(-4.5).should be_an_instance_of(Complex)
+        Complex(-4.5).should.instance_of?(Complex)
         Complex(-4.5).imag.should == 0
         Complex(-4.5).real.should == -4.5
 
-        Complex(bignum_value).should be_an_instance_of(Complex)
+        Complex(bignum_value).should.instance_of?(Complex)
         Complex(bignum_value).imag.should == 0
         Complex(bignum_value).real.should == bignum_value
       end
     end
   end
 
-  describe "when passed a String" do
+  describe "when passed [String]" do
+    it_behaves_like :kernel_complex, :Complex_method, KernelSpecs
+
+    context "invalid argument" do
+      it "raises Encoding::CompatibilityError if String is in not ASCII-compatible encoding" do
+        -> {
+          Complex("79+4i".encode("UTF-16"))
+        }.should.raise(Encoding::CompatibilityError, "ASCII incompatible encoding: UTF-16")
+      end
+
+      it "raises ArgumentError for unrecognised Strings" do
+        -> {
+          Complex("ruby")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "ruby"')
+      end
+
+      it "raises ArgumentError for trailing garbage" do
+        -> {
+          Complex("79+4iruby")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "79+4iruby"')
+      end
+
+      it "does not understand Float::INFINITY" do
+        -> {
+          Complex("Infinity")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "Infinity"')
+
+        -> {
+          Complex("-Infinity")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "-Infinity"')
+      end
+
+      it "does not understand Float::NAN" do
+        -> {
+          Complex("NaN")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "NaN"')
+      end
+
+      it "does not understand a sequence of _" do
+        -> {
+          Complex("7__9+4__0i")
+        }.should.raise(ArgumentError, 'invalid value for convert(): "7__9+4__0i"')
+      end
+
+      it "does not allow null-byte" do
+        -> {
+          Complex("1-2i\0")
+        }.should.raise(ArgumentError, "string contains null byte")
+      end
+    end
+
+    context "invalid argument and exception: false passed" do
+      it "raises Encoding::CompatibilityError if String is in not ASCII-compatible encoding" do
+        -> {
+          Complex("79+4i".encode("UTF-16"), exception: false)
+        }.should.raise(Encoding::CompatibilityError, "ASCII incompatible encoding: UTF-16")
+      end
+
+      it "returns nil for unrecognised Strings" do
+        Complex("ruby", exception: false).should == nil
+      end
+
+      it "returns nil when trailing garbage" do
+        Complex("79+4iruby", exception: false).should == nil
+      end
+
+      it "returns nil for Float::INFINITY" do
+        Complex("Infinity", exception: false).should == nil
+        Complex("-Infinity", exception: false).should == nil
+      end
+
+      it "returns nil for Float::NAN" do
+        Complex("NaN", exception: false).should == nil
+      end
+
+      it "returns nil when there is a sequence of _" do
+        Complex("7__9+4__0i", exception: false).should == nil
+      end
+
+      it "returns nil when String contains null-byte" do
+        Complex("1-2i\0", exception: false).should == nil
+      end
+    end
+  end
+
+  describe "when passes [String, String]" do
     it "needs to be reviewed for spec completeness"
   end
 
@@ -73,7 +160,7 @@ describe "Kernel.Complex()" do
     it "returns the passed argument" do
       n = mock_numeric("unreal")
       n.should_receive(:real?).any_number_of_times.and_return(false)
-      Complex(n).should equal(n)
+      Complex(n).should.equal?(n)
     end
   end
 
@@ -82,8 +169,8 @@ describe "Kernel.Complex()" do
       n = mock_numeric("real")
       n.should_receive(:real?).any_number_of_times.and_return(true)
       result = Complex(n)
-      result.real.should equal(n)
-      result.imag.should equal(0)
+      result.real.should.equal?(n)
+      result.imag.should.equal?(0)
     end
   end
 
@@ -98,7 +185,7 @@ describe "Kernel.Complex()" do
         n2.should_receive(:real?).any_number_of_times.and_return(r2)
         n2.should_receive(:*).with(Complex(0, 1)).and_return(n3)
         n1.should_receive(:+).with(n3).and_return(n4)
-        Complex(n1, n2).should equal(n4)
+        Complex(n1, n2).should.equal?(n4)
       end
     end
   end
@@ -110,8 +197,8 @@ describe "Kernel.Complex()" do
       n1.should_receive(:real?).any_number_of_times.and_return(true)
       n2.should_receive(:real?).any_number_of_times.and_return(true)
       result = Complex(n1, n2)
-      result.real.should equal(n1)
-      result.imag.should equal(n2)
+      result.real.should.equal?(n1)
+      result.imag.should.equal?(n2)
     end
   end
 
@@ -120,68 +207,70 @@ describe "Kernel.Complex()" do
       n = mock("n")
       c = Complex(0, 0)
       n.should_receive(:to_c).and_return(c)
-      Complex(n).should equal(c)
+      Complex(n).should.equal?(c)
     end
   end
 
   describe "when passed a non-Numeric second argument" do
     it "raises TypeError" do
-      -> { Complex(:sym, :sym) }.should raise_error(TypeError)
-      -> { Complex(0,    :sym) }.should raise_error(TypeError)
+      -> { Complex(:sym, :sym) }.should.raise(TypeError)
+      -> { Complex(0,    :sym) }.should.raise(TypeError)
     end
   end
 
   describe "when passed nil" do
     it "raises TypeError" do
-      -> { Complex(nil) }.should raise_error(TypeError, "can't convert nil into Complex")
-      -> { Complex(0, nil) }.should raise_error(TypeError, "can't convert nil into Complex")
-      -> { Complex(nil, 0) }.should raise_error(TypeError, "can't convert nil into Complex")
+      -> { Complex(nil) }.should.raise(TypeError, "can't convert nil into Complex")
+      -> { Complex(0, nil) }.should.raise(TypeError, "can't convert nil into Complex")
+      -> { Complex(nil, 0) }.should.raise(TypeError, "can't convert nil into Complex")
     end
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and [Numeric]" do
-        it "returns a complex number" do
-          Complex("123", exception: false).should == Complex(123)
-        end
+  describe "when passed exception: false" do
+    describe "and [Numeric]" do
+      it "returns a complex number" do
+        Complex("123", exception: false).should == Complex(123)
       end
+    end
 
-      describe "and [non-Numeric]" do
-        it "swallows an error" do
-          Complex(:sym, exception: false).should == nil
-        end
+    describe "and [non-Numeric]" do
+      it "swallows an error" do
+        Complex(:sym, exception: false).should == nil
       end
+    end
 
-      describe "and [non-Numeric, Numeric] argument" do
-        it "throws a TypeError" do
-          -> { Complex(:sym, 0, exception: false) }.should raise_error(TypeError, "not a real")
-        end
+    describe "and [non-Numeric, Numeric] argument" do
+      it "throws a TypeError" do
+        -> { Complex(:sym, 0, exception: false) }.should.raise(TypeError, "not a real")
       end
+    end
 
-      describe "and [anything, non-Numeric] argument" do
-        it "swallows an error" do
-          Complex("a",  :sym, exception: false).should == nil
-          Complex(:sym, :sym, exception: false).should == nil
-          Complex(0,    :sym, exception: false).should == nil
-        end
+    describe "and [anything, non-Numeric] argument" do
+      it "swallows an error" do
+        Complex("a",  :sym, exception: false).should == nil
+        Complex(:sym, :sym, exception: false).should == nil
+        Complex(0,    :sym, exception: false).should == nil
       end
+    end
 
-      describe "and non-numeric String arguments" do
-        it "swallows an error" do
-          Complex("a", "b", exception: false).should == nil
-          Complex("a", 0, exception: false).should == nil
-          Complex(0, "b", exception: false).should == nil
-        end
+    describe "and non-numeric String arguments" do
+      it "swallows an error" do
+        Complex("a", "b", exception: false).should == nil
+        Complex("a", 0, exception: false).should == nil
+        Complex(0, "b", exception: false).should == nil
       end
+    end
 
-      describe "and nil arguments" do
-        it "swallows an error" do
-          Complex(nil, exception: false).should == nil
-          Complex(0, nil, exception: false).should == nil
-          Complex(nil, 0, exception: false).should == nil
-        end
+    describe "and nil arguments" do
+      it "swallows an error" do
+        Complex(nil, exception: false).should == nil
+        Complex(0, nil, exception: false).should == nil
+        Complex(nil, 0, exception: false).should == nil
       end
     end
   end
+
+  it "freezes its result" do
+    Complex(1).frozen?.should == true
+  end
 end
diff --git a/spec/ruby/core/kernel/Float_spec.rb b/spec/ruby/core/kernel/Float_spec.rb
index 6580c38137..f5566067ba 100644
--- a/spec/ruby/core/kernel/Float_spec.rb
+++ b/spec/ruby/core/kernel/Float_spec.rb
@@ -6,7 +6,7 @@ describe :kernel_float, shared: true do
     float = 1.12
     float2 = @object.send(:Float, float)
     float2.should == float
-    float2.should equal float
+    float2.should.equal? float
   end
 
   it "returns a Float for Fixnums" do
@@ -22,26 +22,26 @@ describe :kernel_float, shared: true do
   end
 
   it "raises an ArgumentError for nil" do
-    -> { @object.send(:Float, nil) }.should raise_error(TypeError)
+    -> { @object.send(:Float, nil) }.should.raise(TypeError)
   end
 
   it "returns the identical NaN for NaN" do
     nan = nan_value
-    nan.nan?.should be_true
+    nan.nan?.should == true
     nan2 = @object.send(:Float, nan)
-    nan2.nan?.should be_true
-    nan2.should equal(nan)
+    nan2.nan?.should == true
+    nan2.should.equal?(nan)
   end
 
   it "returns the same Infinity for Infinity" do
     infinity = infinity_value
     infinity2 = @object.send(:Float, infinity)
     infinity2.should == infinity_value
-    infinity.should equal(infinity2)
+    infinity.should.equal?(infinity2)
   end
 
   it "converts Strings to floats without calling #to_f" do
-    string = "10"
+    string = +"10"
     string.should_not_receive(:to_f)
     @object.send(:Float, string).should == 10.0
   end
@@ -51,24 +51,30 @@ describe :kernel_float, shared: true do
   end
 
   it "raises an ArgumentError for a String of word characters" do
-    -> { @object.send(:Float, "float") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "float") }.should.raise(ArgumentError)
+  end
+
+  it "raises an ArgumentError for a String with string in error message" do
+    -> { @object.send(:Float, "foo") }.should.raise(ArgumentError) { |e|
+      e.message.should == 'invalid value for Float(): "foo"'
+    }
   end
 
   it "raises an ArgumentError if there are two decimal points in the String" do
-    -> { @object.send(:Float, "10.0.0") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "10.0.0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String of numbers followed by word characters" do
-    -> { @object.send(:Float, "10D") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "10D") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String of word characters followed by numbers" do
-    -> { @object.send(:Float, "D10") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "D10") }.should.raise(ArgumentError)
   end
 
   it "is strict about the string form even across newlines" do
-    -> { @object.send(:Float, "not a number\n10") }.should raise_error(ArgumentError)
-    -> { @object.send(:Float, "10\nnot a number") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "not a number\n10") }.should.raise(ArgumentError)
+    -> { @object.send(:Float, "10\nnot a number") }.should.raise(ArgumentError)
   end
 
   it "converts String subclasses to floats without calling #to_f" do
@@ -90,17 +96,17 @@ describe :kernel_float, shared: true do
   end
 
   it "raises an ArgumentError if a + or - is embedded in a String" do
-    -> { @object.send(:Float, "1+1") }.should raise_error(ArgumentError)
-    -> { @object.send(:Float, "1-1") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "1+1") }.should.raise(ArgumentError)
+    -> { @object.send(:Float, "1-1") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if a String has a trailing + or -" do
-    -> { @object.send(:Float, "11+") }.should raise_error(ArgumentError)
-    -> { @object.send(:Float, "11-") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "11+") }.should.raise(ArgumentError)
+    -> { @object.send(:Float, "11-") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String with a leading _" do
-    -> { @object.send(:Float, "_1") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "_1") }.should.raise(ArgumentError)
   end
 
   it "returns a value for a String with an embedded _" do
@@ -108,31 +114,31 @@ describe :kernel_float, shared: true do
   end
 
   it "raises an ArgumentError for a String with a trailing _" do
-    -> { @object.send(:Float, "10_") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "10_") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String of \\0" do
-    -> { @object.send(:Float, "\0") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "\0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String with a leading \\0" do
-    -> { @object.send(:Float, "\01") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "\01") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String with an embedded \\0" do
-    -> { @object.send(:Float, "1\01") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "1\01") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String with a trailing \\0" do
-    -> { @object.send(:Float, "1\0") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "1\0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String that is just an empty space" do
-    -> { @object.send(:Float, " ") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, " ") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a String that with an embedded space" do
-    -> { @object.send(:Float, "1 2") }.should raise_error(ArgumentError)
+    -> { @object.send(:Float, "1 2") }.should.raise(ArgumentError)
   end
 
   it "returns a value for a String with a leading space" do
@@ -151,13 +157,33 @@ describe :kernel_float, shared: true do
     @object.send(:Float, "1\t\n").should == 1.0
   end
 
+  ruby_version_is ""..."3.4" do
+    it "raises ArgumentError if a fractional part is missing" do
+      -> { @object.send(:Float, "1.") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "+1.") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "-1.") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "1.e+0") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "1.e-2") }.should.raise(ArgumentError)
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "allows String representation without a fractional part" do
+      @object.send(:Float, "1.").should == 1.0
+      @object.send(:Float, "+1.").should == 1.0
+      @object.send(:Float, "-1.").should == -1.0
+      @object.send(:Float, "1.e+0").should == 1.0
+      @object.send(:Float, "1.e-2").should be_close(0.01, TOLERANCE)
+    end
+  end
+
   %w(e E).each do |e|
     it "raises an ArgumentError if #{e} is the trailing character" do
-      -> { @object.send(:Float, "2#{e}") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "2#{e}") }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError if #{e} is the leading character" do
-      -> { @object.send(:Float, "#{e}2") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "#{e}2") }.should.raise(ArgumentError)
     end
 
     it "returns Infinity for '2#{e}1000'" do
@@ -175,18 +201,18 @@ describe :kernel_float, shared: true do
     end
 
     it "raises an exception if a space is embedded on either side of the '#{e}'" do
-      -> { @object.send(:Float, "2 0#{e}100") }.should raise_error(ArgumentError)
-      -> { @object.send(:Float, "20#{e}1 00") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "2 0#{e}100") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "20#{e}1 00") }.should.raise(ArgumentError)
     end
 
     it "raises an exception if there's a leading _ on either side of the '#{e}'" do
-      -> { @object.send(:Float, "_20#{e}100") }.should raise_error(ArgumentError)
-      -> { @object.send(:Float, "20#{e}_100") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "_20#{e}100") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "20#{e}_100") }.should.raise(ArgumentError)
     end
 
     it "raises an exception if there's a trailing _ on either side of the '#{e}'" do
-      -> { @object.send(:Float, "20_#{e}100") }.should raise_error(ArgumentError)
-      -> { @object.send(:Float, "20#{e}100_") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "20_#{e}100") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "20#{e}100_") }.should.raise(ArgumentError)
     end
 
     it "allows decimal points on the left side of the '#{e}'" do
@@ -194,63 +220,111 @@ describe :kernel_float, shared: true do
     end
 
     it "raises an ArgumentError if there's a decimal point on the right side of the '#{e}'" do
-      -> { @object.send(:Float, "20#{e}2.0") }.should raise_error(ArgumentError)
+      -> { @object.send(:Float, "20#{e}2.0") }.should.raise(ArgumentError)
     end
   end
 
-  describe "for hexadecimal literals with binary exponent" do
-    %w(p P).each do |p|
-      it "interprets the fractional part (on the left side of '#{p}') in hexadecimal" do
-        @object.send(:Float, "0x10#{p}0").should == 16.0
-      end
+  context "for hexadecimal literals" do
+    it "interprets the 0x prefix as hexadecimal" do
+      @object.send(:Float, "0x10").should == 16.0
+      @object.send(:Float, "0x0F").should == 15.0
+      @object.send(:Float, "0x0f").should == 15.0
+    end
 
-      it "interprets the exponent (on the right of '#{p}') in decimal" do
-        @object.send(:Float, "0x1#{p}10").should == 1024.0
-      end
+    it "interprets negative hex value" do
+      @object.send(:Float, "-0x10").should == -16.0
+    end
 
-      it "raises an ArgumentError if #{p} is the trailing character" do
-        -> { @object.send(:Float, "0x1#{p}") }.should raise_error(ArgumentError)
-      end
+    it "accepts embedded _ if the number does not contain a-f" do
+      @object.send(:Float, "0x1_0").should == 16.0
+    end
 
-      it "raises an ArgumentError if #{p} is the leading character" do
-        -> { @object.send(:Float, "0x#{p}1") }.should raise_error(ArgumentError)
+    ruby_version_is ""..."3.4.3" do
+      it "does not accept embedded _ if the number contains a-f" do
+        -> { @object.send(:Float, "0x1_0a") }.should.raise(ArgumentError)
+        @object.send(:Float, "0x1_0a", exception: false).should == nil
       end
+    end
 
-      it "returns Infinity for '0x1#{p}10000'" do
-        @object.send(:Float, "0x1#{p}10000").should == Float::INFINITY
+    ruby_version_is "3.4.3" do
+      it "accepts embedded _ if the number contains a-f" do
+        @object.send(:Float, "0x1_0a").should == 0x10a.to_f
       end
+    end
 
-      it "returns 0 for '0x1#{p}-10000'" do
-        @object.send(:Float, "0x1#{p}-10000").should == 0
-      end
+    it "does not accept _ before, after or inside the 0x prefix" do
+      -> { @object.send(:Float, "_0x10") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "0_x10") }.should.raise(ArgumentError)
+      -> { @object.send(:Float, "0x_10") }.should.raise(ArgumentError)
+      @object.send(:Float, "_0x10", exception: false).should == nil
+      @object.send(:Float, "0_x10", exception: false).should == nil
+      @object.send(:Float, "0x_10", exception: false).should == nil
+    end
 
-      it "allows embedded _ in a number on either side of the #{p}" do
-        @object.send(:Float, "0x1_0#{p}10").should == 16384.0
-        @object.send(:Float, "0x10#{p}1_0").should == 16384.0
-        @object.send(:Float, "0x1_0#{p}1_0").should == 16384.0
-      end
+    it "parses negative hexadecimal string as negative float" do
+      @object.send(:Float, "-0x7b").should == -123.0
+    end
 
-      it "raises an exception if a space is embedded on either side of the '#{p}'" do
-        -> { @object.send(:Float, "0x1 0#{p}10") }.should raise_error(ArgumentError)
-        -> { @object.send(:Float, "0x10#{p}1 0") }.should raise_error(ArgumentError)
+    ruby_version_is "3.4" do
+      it "accepts a fractional part" do
+        @object.send(:Float, "0x0.8").should == 0.5
       end
+    end
 
-      it "raises an exception if there's a leading _ on either side of the '#{p}'" do
-        -> { @object.send(:Float, "0x_10#{p}10") }.should raise_error(ArgumentError)
-        -> { @object.send(:Float, "0x10#{p}_10") }.should raise_error(ArgumentError)
-      end
+    describe "with binary exponent" do
+      %w(p P).each do |p|
+        it "interprets the fractional part (on the left side of '#{p}') in hexadecimal" do
+          @object.send(:Float, "0x10#{p}0").should == 16.0
+        end
 
-      it "raises an exception if there's a trailing _ on either side of the '#{p}'" do
-        -> { @object.send(:Float, "0x10_#{p}10") }.should raise_error(ArgumentError)
-        -> { @object.send(:Float, "0x10#{p}10_") }.should raise_error(ArgumentError)
-      end
+        it "interprets the exponent (on the right of '#{p}') in decimal" do
+          @object.send(:Float, "0x1#{p}10").should == 1024.0
+        end
 
-      it "allows hexadecimal points on the left side of the '#{p}'" do
-        @object.send(:Float, "0x1.8#{p}0").should == 1.5
-      end
+        it "raises an ArgumentError if #{p} is the trailing character" do
+          -> { @object.send(:Float, "0x1#{p}") }.should.raise(ArgumentError)
+        end
+
+        it "raises an ArgumentError if #{p} is the leading character" do
+          -> { @object.send(:Float, "0x#{p}1") }.should.raise(ArgumentError)
+        end
+
+        it "returns Infinity for '0x1#{p}10000'" do
+          @object.send(:Float, "0x1#{p}10000").should == Float::INFINITY
+        end
+
+        it "returns 0 for '0x1#{p}-10000'" do
+          @object.send(:Float, "0x1#{p}-10000").should == 0
+        end
+
+        it "allows embedded _ in a number on either side of the #{p}" do
+          @object.send(:Float, "0x1_0#{p}10").should == 16384.0
+          @object.send(:Float, "0x10#{p}1_0").should == 16384.0
+          @object.send(:Float, "0x1_0#{p}1_0").should == 16384.0
+        end
+
+        it "raises an exception if a space is embedded on either side of the '#{p}'" do
+          -> { @object.send(:Float, "0x1 0#{p}10") }.should.raise(ArgumentError)
+          -> { @object.send(:Float, "0x10#{p}1 0") }.should.raise(ArgumentError)
+        end
 
-      it "raises an ArgumentError if there's a decimal point on the right side of the '#{p}'" do
-        -> { @object.send(:Float, "0x1#{p}1.0") }.should raise_error(ArgumentError)
+        it "raises an exception if there's a leading _ on either side of the '#{p}'" do
+          -> { @object.send(:Float, "0x_10#{p}10") }.should.raise(ArgumentError)
+          -> { @object.send(:Float, "0x10#{p}_10") }.should.raise(ArgumentError)
+        end
+
+        it "raises an exception if there's a trailing _ on either side of the '#{p}'" do
+          -> { @object.send(:Float, "0x10_#{p}10") }.should.raise(ArgumentError)
+          -> { @object.send(:Float, "0x10#{p}10_") }.should.raise(ArgumentError)
+        end
+
+        it "allows hexadecimal points on the left side of the '#{p}'" do
+          @object.send(:Float, "0x1.8#{p}0").should == 1.5
+        end
+
+        it "raises an ArgumentError if there's a decimal point on the right side of the '#{p}'" do
+          -> { @object.send(:Float, "0x1#{p}1.0") }.should.raise(ArgumentError)
+        end
       end
     end
   end
@@ -270,57 +344,55 @@ describe :kernel_float, shared: true do
     nan = nan_value
     (nan_to_f = mock('NaN')).should_receive(:to_f).once.and_return(nan)
     nan2 = @object.send(:Float, nan_to_f)
-    nan2.nan?.should be_true
-    nan2.should equal(nan)
+    nan2.nan?.should == true
+    nan2.should.equal?(nan)
   end
 
-  it "returns the identical Infinity if to_f is called and it returns Infinity" do
+  it "returns the identical Infinity if #to_f is called and it returns Infinity" do
     infinity = infinity_value
     (infinity_to_f = mock('Infinity')).should_receive(:to_f).once.and_return(infinity)
     infinity2 = @object.send(:Float, infinity_to_f)
-    infinity2.should equal(infinity)
+    infinity2.should.equal?(infinity)
   end
 
   it "raises a TypeError if #to_f is not provided" do
-    -> { @object.send(:Float, mock('x')) }.should raise_error(TypeError)
+    -> { @object.send(:Float, mock('x')) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_f returns a String" do
     (obj = mock('ha!')).should_receive(:to_f).once.and_return('ha!')
-    -> { @object.send(:Float, obj) }.should raise_error(TypeError)
+    -> { @object.send(:Float, obj) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_f returns an Integer" do
     (obj = mock('123')).should_receive(:to_f).once.and_return(123)
-    -> { @object.send(:Float, obj) }.should raise_error(TypeError)
+    -> { @object.send(:Float, obj) }.should.raise(TypeError)
   end
 
   it "raises a RangeError when passed a Complex argument" do
     c = Complex(2, 3)
-    -> { @object.send(:Float, c) }.should raise_error(RangeError)
+    -> { @object.send(:Float, c) }.should.raise(RangeError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and valid input" do
-        it "returns a Float number" do
-          @object.send(:Float, 1, exception: false).should == 1.0
-          @object.send(:Float, "1", exception: false).should == 1.0
-          @object.send(:Float, "1.23", exception: false).should == 1.23
-        end
+  describe "when passed exception: false" do
+    describe "and valid input" do
+      it "returns a Float number" do
+        @object.send(:Float, 1, exception: false).should == 1.0
+        @object.send(:Float, "1", exception: false).should == 1.0
+        @object.send(:Float, "1.23", exception: false).should == 1.23
       end
+    end
 
-      describe "and invalid input" do
-        it "swallows an error" do
-          @object.send(:Float, "abc", exception: false).should == nil
-          @object.send(:Float, :sym, exception: false).should == nil
-        end
+    describe "and invalid input" do
+      it "swallows an error" do
+        @object.send(:Float, "abc", exception: false).should == nil
+        @object.send(:Float, :sym, exception: false).should == nil
       end
+    end
 
-      describe "and nil" do
-        it "swallows it" do
-          @object.send(:Float, nil, exception: false).should == nil
-        end
+    describe "and nil" do
+      it "swallows it" do
+        @object.send(:Float, nil, exception: false).should == nil
       end
     end
   end
@@ -336,6 +408,6 @@ end
 
 describe "Kernel#Float" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:Float)
+    Kernel.private_instance_methods(false).should.include?(:Float)
   end
 end
diff --git a/spec/ruby/core/kernel/Hash_spec.rb b/spec/ruby/core/kernel/Hash_spec.rb
index cbe098a8ac..ee16f56a90 100644
--- a/spec/ruby/core/kernel/Hash_spec.rb
+++ b/spec/ruby/core/kernel/Hash_spec.rb
@@ -13,7 +13,7 @@ end
 
 describe "Kernel" do
   it "has private instance method Hash()" do
-    Kernel.should have_private_instance_method(:Hash)
+    Kernel.private_instance_methods(false).should.include?(:Hash)
   end
 end
 
@@ -43,14 +43,14 @@ describe :kernel_Hash, shared: true do
   end
 
   it "raises a TypeError if it doesn't respond to #to_hash" do
-    -> { @object.send(@method, mock("")) }.should raise_error(TypeError)
+    -> { @object.send(@method, mock("")) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_hash does not return an Hash" do
     obj = mock("Hash() string")
     obj.should_receive(:to_hash).and_return("string")
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 end
 
diff --git a/spec/ruby/core/kernel/Integer_spec.rb b/spec/ruby/core/kernel/Integer_spec.rb
index 59b41d37e6..978fd8ef08 100644
--- a/spec/ruby/core/kernel/Integer_spec.rb
+++ b/spec/ruby/core/kernel/Integer_spec.rb
@@ -10,38 +10,52 @@ describe :kernel_integer, shared: true do
     Integer(100).should == 100
   end
 
-  ruby_version_is ""..."2.6" do
-    it "uncritically return the value of to_int even if it is not an Integer" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_not_receive(:to_i)
-      Integer(obj).should == "1"
-    end
+  it "raises a TypeError when to_int returns not-an-Integer object and to_i returns nil" do
+    obj = mock("object")
+    obj.should_receive(:to_int).and_return("1")
+    obj.should_receive(:to_i).and_return(nil)
+    -> {
+      Integer(obj)
+    }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_i gives nil)")
   end
 
-  ruby_version_is "2.6" do
-    it "raises a TypeError when to_int returns not-an-Integer object and to_i returns nil" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_receive(:to_i).and_return(nil)
-      -> { Integer(obj) }.should raise_error(TypeError)
-    end
+  it "return a result of to_i when to_int does not return an Integer" do
+    obj = mock("object")
+    obj.should_receive(:to_int).and_return("1")
+    obj.should_receive(:to_i).and_return(42)
+    Integer(obj).should == 42
+  end
 
-    it "return a result of to_i when to_int does not return an Integer" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_receive(:to_i).and_return(42)
-      Integer(obj).should == 42
-    end
+  it "returns a result of to_str" do
+    obj = mock("obj")
+    obj.should_receive(:to_str).and_return("1")
+
+    Integer(obj).should == 1
+  end
+
+  it "returns a result of to_int when both to_int and to_str are defined" do
+    obj = mock("obj")
+    obj.should_receive(:to_int).and_return(1)
+    obj.should_not_receive(:to_str)
+
+    Integer(obj).should == 1
+  end
+
+  it "returns a result of to_str when both to_str and to_i are defined" do
+    obj = mock("obj")
+    obj.should_receive(:to_str).and_return("1")
+    obj.should_not_receive(:to_i)
+
+    Integer(obj).should == 1
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Integer(nil) }.should raise_error(TypeError)
+    -> { Integer(nil) }.should.raise(TypeError, "can't convert nil into Integer")
   end
 
-  it "returns a Fixnum or Bignum object" do
-    Integer(2).should be_an_instance_of(Fixnum)
-    Integer(9**99).should be_an_instance_of(Bignum)
+  it "returns an Integer object" do
+    Integer(2).should.instance_of?(Integer)
+    Integer(9**99).should.instance_of?(Integer)
   end
 
   it "truncates Floats" do
@@ -78,101 +92,105 @@ describe :kernel_integer, shared: true do
   it "raises a TypeError if to_i returns a value that is not an Integer" do
     obj = mock("object")
     obj.should_receive(:to_i).and_return("1")
-    -> { Integer(obj) }.should raise_error(TypeError)
+    -> {
+      Integer(obj)
+    }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_i gives String)")
   end
 
   it "raises a TypeError if no to_int or to_i methods exist" do
     obj = mock("object")
-    -> { Integer(obj) }.should raise_error(TypeError)
+    -> {
+      Integer(obj)
+    }.should.raise(TypeError, "can't convert MockObject into Integer")
   end
 
   it "raises a TypeError if to_int returns nil and no to_i exists" do
     obj = mock("object")
     obj.should_receive(:to_i).and_return(nil)
-    -> { Integer(obj) }.should raise_error(TypeError)
+    -> {
+      Integer(obj)
+    }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_i gives nil)")
   end
 
   it "raises a FloatDomainError when passed NaN" do
-    -> { Integer(nan_value) }.should raise_error(FloatDomainError)
+    -> { Integer(nan_value) }.should.raise(FloatDomainError)
   end
 
   it "raises a FloatDomainError when passed Infinity" do
-    -> { Integer(infinity_value) }.should raise_error(FloatDomainError)
+    -> { Integer(infinity_value) }.should.raise(FloatDomainError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and to_i returns a value that is not an Integer" do
-        it "swallows an error" do
-          obj = mock("object")
-          obj.should_receive(:to_i).and_return("1")
-          Integer(obj, exception: false).should == nil
-        end
+  describe "when passed exception: false" do
+    describe "and to_i returns a value that is not an Integer" do
+      it "swallows an error" do
+        obj = mock("object")
+        obj.should_receive(:to_i).and_return("1")
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and no to_int or to_i methods exist" do
-        it "swallows an error" do
-          obj = mock("object")
-          Integer(obj, exception: false).should == nil
-        end
+    describe "and no to_int or to_i methods exist" do
+      it "swallows an error" do
+        obj = mock("object")
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and to_int returns nil and no to_i exists" do
-        it "swallows an error" do
-          obj = mock("object")
-          obj.should_receive(:to_i).and_return(nil)
-          Integer(obj, exception: false).should == nil
-        end
+    describe "and to_int returns nil and no to_i exists" do
+      it "swallows an error" do
+        obj = mock("object")
+        obj.should_receive(:to_i).and_return(nil)
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and passed NaN" do
-        it "swallows an error" do
-          Integer(nan_value, exception: false).should == nil
-        end
+    describe "and passed NaN" do
+      it "swallows an error" do
+        Integer(nan_value, exception: false).should == nil
       end
+    end
 
-      describe "and passed Infinity" do
-        it "swallows an error" do
-          Integer(infinity_value, exception: false).should == nil
-        end
+    describe "and passed Infinity" do
+      it "swallows an error" do
+        Integer(infinity_value, exception: false).should == nil
       end
+    end
 
-      describe "and passed nil" do
-        it "swallows an error" do
-          Integer(nil, exception: false).should == nil
-        end
+    describe "and passed nil" do
+      it "swallows an error" do
+        Integer(nil, exception: false).should == nil
       end
+    end
 
-      describe "and passed a String that contains numbers" do
-        it "normally parses it and returns an Integer" do
-          Integer("42", exception: false).should == 42
-        end
+    describe "and passed a String that contains numbers" do
+      it "normally parses it and returns an Integer" do
+        Integer("42", exception: false).should == 42
       end
+    end
 
-      describe "and passed a String that can't be converted to an Integer" do
-        it "swallows an error" do
-          Integer("abc", exception: false).should == nil
-        end
+    describe "and passed a String that can't be converted to an Integer" do
+      it "swallows an error" do
+        Integer("abc", exception: false).should == nil
       end
     end
   end
 end
 
-describe "Integer() given a String", shared: true do
+describe :kernel_integer_string, shared: true do
   it "raises an ArgumentError if the String is a null byte" do
-    -> { Integer("\0") }.should raise_error(ArgumentError)
+    -> { Integer("\0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String starts with a null byte" do
-    -> { Integer("\01") }.should raise_error(ArgumentError)
+    -> { Integer("\01") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String ends with a null byte" do
-    -> { Integer("1\0") }.should raise_error(ArgumentError)
+    -> { Integer("1\0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String contains a null byte" do
-    -> { Integer("1\01") }.should raise_error(ArgumentError)
+    -> { Integer("1\01") }.should.raise(ArgumentError)
   end
 
   it "ignores leading whitespace" do
@@ -188,13 +206,13 @@ describe "Integer() given a String", shared: true do
   end
 
   it "raises an ArgumentError if there are leading _s" do
-    -> { Integer("_1") }.should raise_error(ArgumentError)
-    -> { Integer("___1") }.should raise_error(ArgumentError)
+    -> { Integer("_1") }.should.raise(ArgumentError)
+    -> { Integer("___1") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing _s" do
-    -> { Integer("1_") }.should raise_error(ArgumentError)
-    -> { Integer("1___") }.should raise_error(ArgumentError)
+    -> { Integer("1_") }.should.raise(ArgumentError)
+    -> { Integer("1___") }.should.raise(ArgumentError)
   end
 
   it "ignores an embedded _" do
@@ -202,8 +220,8 @@ describe "Integer() given a String", shared: true do
   end
 
   it "raises an ArgumentError if there are multiple embedded _s" do
-    -> { Integer("1__1") }.should raise_error(ArgumentError)
-    -> { Integer("1___1") }.should raise_error(ArgumentError)
+    -> { Integer("1__1") }.should.raise(ArgumentError)
+    -> { Integer("1___1") }.should.raise(ArgumentError)
   end
 
   it "ignores a single leading +" do
@@ -211,17 +229,17 @@ describe "Integer() given a String", shared: true do
   end
 
   it "raises an ArgumentError if there is a space between the + and number" do
-    -> { Integer("+ 1") }.should raise_error(ArgumentError)
+    -> { Integer("+ 1") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are multiple leading +s" do
-    -> { Integer("++1") }.should raise_error(ArgumentError)
-    -> { Integer("+++1") }.should raise_error(ArgumentError)
+    -> { Integer("++1") }.should.raise(ArgumentError)
+    -> { Integer("+++1") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing +s" do
-    -> { Integer("1+") }.should raise_error(ArgumentError)
-    -> { Integer("1+++") }.should raise_error(ArgumentError)
+    -> { Integer("1+") }.should.raise(ArgumentError)
+    -> { Integer("1+++") }.should.raise(ArgumentError)
   end
 
   it "makes the number negative if there's a leading -" do
@@ -229,47 +247,45 @@ describe "Integer() given a String", shared: true do
   end
 
   it "raises an ArgumentError if there are multiple leading -s" do
-    -> { Integer("--1") }.should raise_error(ArgumentError)
-    -> { Integer("---1") }.should raise_error(ArgumentError)
+    -> { Integer("--1") }.should.raise(ArgumentError)
+    -> { Integer("---1") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing -s" do
-    -> { Integer("1-") }.should raise_error(ArgumentError)
-    -> { Integer("1---") }.should raise_error(ArgumentError)
+    -> { Integer("1-") }.should.raise(ArgumentError)
+    -> { Integer("1---") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there is a period" do
-    -> { Integer("0.0") }.should raise_error(ArgumentError)
+    -> { Integer("0.0") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for an empty String" do
-    -> { Integer("") }.should raise_error(ArgumentError)
+    -> { Integer("") }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and multiple leading -s" do
-        it "swallows an error" do
-          Integer("---1", exception: false).should == nil
-        end
+  describe "when passed exception: false" do
+    describe "and multiple leading -s" do
+      it "swallows an error" do
+        Integer("---1", exception: false).should == nil
       end
+    end
 
-      describe "and multiple trailing -s" do
-        it "swallows an error" do
-          Integer("1---", exception: false).should == nil
-        end
+    describe "and multiple trailing -s" do
+      it "swallows an error" do
+        Integer("1---", exception: false).should == nil
       end
+    end
 
-      describe "and an argument that contains a period" do
-        it "swallows an error" do
-          Integer("0.0", exception: false).should == nil
-        end
+    describe "and an argument that contains a period" do
+      it "swallows an error" do
+        Integer("0.0", exception: false).should == nil
       end
+    end
 
-      describe "and an empty string" do
-        it "swallows an error" do
-          Integer("", exception: false).should == nil
-        end
+    describe "and an empty string" do
+      it "swallows an error" do
+        Integer("", exception: false).should == nil
       end
     end
   end
@@ -295,7 +311,7 @@ describe "Integer() given a String", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as hex" do
-      -> { Integer("0#{x}g") }.should raise_error(ArgumentError)
+      -> { Integer("0#{x}g") }.should.raise(ArgumentError)
     end
   end
 
@@ -316,7 +332,7 @@ describe "Integer() given a String", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as binary" do
-      -> { Integer("0#{b}2") }.should raise_error(ArgumentError)
+      -> { Integer("0#{b}2") }.should.raise(ArgumentError)
     end
   end
 
@@ -337,7 +353,7 @@ describe "Integer() given a String", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as octal" do
-      -> { Integer("0#{o}9") }.should raise_error(ArgumentError)
+      -> { Integer("0#{o}9") }.should.raise(ArgumentError)
     end
   end
 
@@ -358,26 +374,26 @@ describe "Integer() given a String", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as decimal" do
-      -> { Integer("0#{d}a") }.should raise_error(ArgumentError)
+      -> { Integer("0#{d}a") }.should.raise(ArgumentError)
     end
   end
 end
 
-describe "Integer() given a String and base", shared: true do
+describe :kernel_integer_string_base, shared: true do
   it "raises an ArgumentError if the String is a null byte" do
-    -> { Integer("\0", 2) }.should raise_error(ArgumentError)
+    -> { Integer("\0", 2) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String starts with a null byte" do
-    -> { Integer("\01", 3) }.should raise_error(ArgumentError)
+    -> { Integer("\01", 3) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String ends with a null byte" do
-    -> { Integer("1\0", 4) }.should raise_error(ArgumentError)
+    -> { Integer("1\0", 4) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the String contains a null byte" do
-    -> { Integer("1\01", 5) }.should raise_error(ArgumentError)
+    -> { Integer("1\01", 5) }.should.raise(ArgumentError)
   end
 
   it "ignores leading whitespace" do
@@ -393,13 +409,13 @@ describe "Integer() given a String and base", shared: true do
   end
 
   it "raises an ArgumentError if there are leading _s" do
-    -> { Integer("_1", 7) }.should raise_error(ArgumentError)
-    -> { Integer("___1", 7) }.should raise_error(ArgumentError)
+    -> { Integer("_1", 7) }.should.raise(ArgumentError)
+    -> { Integer("___1", 7) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing _s" do
-    -> { Integer("1_", 12) }.should raise_error(ArgumentError)
-    -> { Integer("1___", 12) }.should raise_error(ArgumentError)
+    -> { Integer("1_", 12) }.should.raise(ArgumentError)
+    -> { Integer("1___", 12) }.should.raise(ArgumentError)
   end
 
   it "ignores an embedded _" do
@@ -407,8 +423,8 @@ describe "Integer() given a String and base", shared: true do
   end
 
   it "raises an ArgumentError if there are multiple embedded _s" do
-    -> { Integer("1__1", 4) }.should raise_error(ArgumentError)
-    -> { Integer("1___1", 4) }.should raise_error(ArgumentError)
+    -> { Integer("1__1", 4) }.should.raise(ArgumentError)
+    -> { Integer("1___1", 4) }.should.raise(ArgumentError)
   end
 
   it "ignores a single leading +" do
@@ -416,17 +432,17 @@ describe "Integer() given a String and base", shared: true do
   end
 
   it "raises an ArgumentError if there is a space between the + and number" do
-    -> { Integer("+ 1", 3) }.should raise_error(ArgumentError)
+    -> { Integer("+ 1", 3) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are multiple leading +s" do
-    -> { Integer("++1", 3) }.should raise_error(ArgumentError)
-    -> { Integer("+++1", 3) }.should raise_error(ArgumentError)
+    -> { Integer("++1", 3) }.should.raise(ArgumentError)
+    -> { Integer("+++1", 3) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing +s" do
-    -> { Integer("1+", 3) }.should raise_error(ArgumentError)
-    -> { Integer("1+++", 12) }.should raise_error(ArgumentError)
+    -> { Integer("1+", 3) }.should.raise(ArgumentError)
+    -> { Integer("1+++", 12) }.should.raise(ArgumentError)
   end
 
   it "makes the number negative if there's a leading -" do
@@ -434,29 +450,29 @@ describe "Integer() given a String and base", shared: true do
   end
 
   it "raises an ArgumentError if there are multiple leading -s" do
-    -> { Integer("--1", 9) }.should raise_error(ArgumentError)
-    -> { Integer("---1", 9) }.should raise_error(ArgumentError)
+    -> { Integer("--1", 9) }.should.raise(ArgumentError)
+    -> { Integer("---1", 9) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there are trailing -s" do
-    -> { Integer("1-", 12) }.should raise_error(ArgumentError)
-    -> { Integer("1---", 12) }.should raise_error(ArgumentError)
+    -> { Integer("1-", 12) }.should.raise(ArgumentError)
+    -> { Integer("1---", 12) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if there is a period" do
-    -> { Integer("0.0", 3) }.should raise_error(ArgumentError)
+    -> { Integer("0.0", 3) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for an empty String" do
-    -> { Integer("", 12) }.should raise_error(ArgumentError)
+    -> { Integer("", 12) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a base of 1" do
-    -> { Integer("1", 1) }.should raise_error(ArgumentError)
+    -> { Integer("1", 1) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for a base of 37" do
-    -> { Integer("1", 37) }.should raise_error(ArgumentError)
+    -> { Integer("1", 37) }.should.raise(ArgumentError)
   end
 
   it "accepts wholly lowercase alphabetic strings for bases > 10" do
@@ -484,8 +500,8 @@ describe "Integer() given a String and base", shared: true do
   end
 
   it "raises an ArgumentError for letters invalid in the given base" do
-    -> { Integer('z',19) }.should raise_error(ArgumentError)
-    -> { Integer('c00o',2) }.should raise_error(ArgumentError)
+    -> { Integer('z',19) }.should.raise(ArgumentError)
+    -> { Integer('c00o',2) }.should.raise(ArgumentError)
   end
 
   %w(x X).each do |x|
@@ -506,12 +522,12 @@ describe "Integer() given a String and base", shared: true do
 
     2.upto(15) do |base|
       it "raises an ArgumentError if the number begins with 0#{x} and the base is #{base}" do
-        -> { Integer("0#{x}1", base) }.should raise_error(ArgumentError)
+        -> { Integer("0#{x}1", base) }.should.raise(ArgumentError)
       end
     end
 
     it "raises an ArgumentError if the number cannot be parsed as hex and the base is 16" do
-      -> { Integer("0#{x}g", 16) }.should raise_error(ArgumentError)
+      -> { Integer("0#{x}g", 16) }.should.raise(ArgumentError)
     end
   end
 
@@ -532,7 +548,7 @@ describe "Integer() given a String and base", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as binary and the base is 2" do
-      -> { Integer("0#{b}2", 2) }.should raise_error(ArgumentError)
+      -> { Integer("0#{b}2", 2) }.should.raise(ArgumentError)
     end
   end
 
@@ -553,12 +569,12 @@ describe "Integer() given a String and base", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as octal and the base is 8" do
-      -> { Integer("0#{o}9", 8) }.should raise_error(ArgumentError)
+      -> { Integer("0#{o}9", 8) }.should.raise(ArgumentError)
     end
 
     2.upto(7) do |base|
       it "raises an ArgumentError if the number begins with 0#{o} and the base is #{base}" do
-        -> { Integer("0#{o}1", base) }.should raise_error(ArgumentError)
+        -> { Integer("0#{o}1", base) }.should.raise(ArgumentError)
       end
     end
   end
@@ -580,34 +596,45 @@ describe "Integer() given a String and base", shared: true do
     end
 
     it "raises an ArgumentError if the number cannot be parsed as decimal and the base is 10" do
-      -> { Integer("0#{d}a", 10) }.should raise_error(ArgumentError)
+      -> { Integer("0#{d}a", 10) }.should.raise(ArgumentError)
     end
 
     2.upto(9) do |base|
       it "raises an ArgumentError if the number begins with 0#{d} and the base is #{base}" do
-        -> { Integer("0#{d}1", base) }.should raise_error(ArgumentError)
+        -> { Integer("0#{d}1", base) }.should.raise(ArgumentError)
       end
     end
+  end
 
-    it "raises an ArgumentError if a base is given for a non-String value" do
-      -> { Integer(98, 15) }.should raise_error(ArgumentError)
-    end
+  it "raises an ArgumentError if a base is given for a non-String value" do
+    -> { Integer(98, 15) }.should.raise(ArgumentError, "base specified for non string value")
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and valid argument" do
-        it "returns an Integer number" do
-          Integer("100", 10, exception: false).should == 100
-          Integer("100", 2, exception: false).should == 4
-        end
+  it "tries to convert the base to an integer using to_int" do
+    obj = mock('8')
+    obj.should_receive(:to_int).and_return(8)
+
+    Integer("777", obj).should == 0777
+  end
+
+  it "raises a TypeError if it is not an integer and does not respond to #to_i" do
+    -> {
+      Integer("777", "8")
+    }.should.raise(TypeError, "no implicit conversion of String into Integer")
+  end
+
+  describe "when passed exception: false" do
+    describe "and valid argument" do
+      it "returns an Integer number" do
+        Integer("100", 10, exception: false).should == 100
+        Integer("100", 2, exception: false).should == 4
       end
+    end
 
-      describe "and invalid argument" do
-        it "swallows an error" do
-          Integer("999", 2, exception: false).should == nil
-          Integer("abc", 10, exception: false).should == nil
-        end
+    describe "and invalid argument" do
+      it "swallows an error" do
+        Integer("999", 2, exception: false).should == nil
+        Integer("abc", 10, exception: false).should == nil
       end
     end
   end
@@ -616,176 +643,176 @@ end
 describe :kernel_Integer, shared: true do
   it "raises an ArgumentError when the String contains digits out of range of radix 2" do
     str = "23456789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 2) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 2) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 3" do
     str = "3456789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 3) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 3) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 4" do
     str = "456789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 4) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 4) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 5" do
     str = "56789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 5) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 5) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 6" do
     str = "6789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 6) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 6) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 7" do
     str = "789abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 7) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 7) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 8" do
     str = "89abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 8) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 8) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 9" do
     str = "9abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 9) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 9) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 10" do
     str = "abcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 10) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 10) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 11" do
     str = "bcdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 11) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 11) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 12" do
     str = "cdefghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 12) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 12) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 13" do
     str = "defghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 13) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 13) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 14" do
     str = "efghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 14) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 14) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 15" do
     str = "fghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 15) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 15) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 16" do
     str = "ghijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 16) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 16) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 17" do
     str = "hijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 17) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 17) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 18" do
     str = "ijklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 18) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 18) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 19" do
     str = "jklmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 19) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 19) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 20" do
     str = "klmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 20) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 20) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 21" do
     str = "lmnopqrstuvwxyz"
-    -> { @object.send(@method, str, 21) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 21) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 22" do
     str = "mnopqrstuvwxyz"
-    -> { @object.send(@method, str, 22) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 22) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 23" do
     str = "nopqrstuvwxyz"
-    -> { @object.send(@method, str, 23) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 23) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 24" do
     str = "opqrstuvwxyz"
-    -> { @object.send(@method, str, 24) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 24) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 25" do
     str = "pqrstuvwxyz"
-    -> { @object.send(@method, str, 25) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 25) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 26" do
     str = "qrstuvwxyz"
-    -> { @object.send(@method, str, 26) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 26) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 27" do
     str = "rstuvwxyz"
-    -> { @object.send(@method, str, 27) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 27) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 28" do
     str = "stuvwxyz"
-    -> { @object.send(@method, str, 28) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 28) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 29" do
     str = "tuvwxyz"
-    -> { @object.send(@method, str, 29) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 29) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 30" do
     str = "uvwxyz"
-    -> { @object.send(@method, str, 30) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 30) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 31" do
     str = "vwxyz"
-    -> { @object.send(@method, str, 31) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 31) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 32" do
     str = "wxyz"
-    -> { @object.send(@method, str, 32) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 32) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 33" do
     str = "xyz"
-    -> { @object.send(@method, str, 33) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 33) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 34" do
     str = "yz"
-    -> { @object.send(@method, str, 34) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 34) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 35" do
     str = "z"
-    -> { @object.send(@method, str, 35) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, str, 35) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the String contains digits out of range of radix 36" do
-    -> { @object.send(@method, "{", 36) }.should raise_error(ArgumentError)
+    -> { @object.send(@method, "{", 36) }.should.raise(ArgumentError)
   end
 end
 
@@ -794,9 +821,9 @@ describe "Kernel.Integer" do
 
   # TODO: fix these specs
   it_behaves_like :kernel_integer, :Integer, Kernel
-  it_behaves_like "Integer() given a String", :Integer
+  it_behaves_like :kernel_integer_string, :Integer
 
-  it_behaves_like "Integer() given a String and base", :Integer
+  it_behaves_like :kernel_integer_string_base, :Integer
 
   it "is a public method" do
     Kernel.Integer(10).should == 10
@@ -808,11 +835,11 @@ describe "Kernel#Integer" do
 
   # TODO: fix these specs
   it_behaves_like :kernel_integer, :Integer, Object.new
-  it_behaves_like "Integer() given a String", :Integer
+  it_behaves_like :kernel_integer_string, :Integer
 
-  it_behaves_like "Integer() given a String and base", :Integer
+  it_behaves_like :kernel_integer_string_base, :Integer
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:Integer)
+    Kernel.private_instance_methods(false).should.include?(:Integer)
   end
 end
diff --git a/spec/ruby/core/kernel/Rational_spec.rb b/spec/ruby/core/kernel/Rational_spec.rb
index 2d1051db7f..b13ab4cf55 100644
--- a/spec/ruby/core/kernel/Rational_spec.rb
+++ b/spec/ruby/core/kernel/Rational_spec.rb
@@ -1,6 +1,236 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/rational/Rational'
+require_relative '../rational/fixtures/rational'
 
 describe "Kernel.Rational" do
-  it_behaves_like :kernel_Rational, :Rational
+  describe "passed Integer" do
+    # Guard against the Mathn library
+    guard -> { !defined?(Math.rsqrt) } do
+      it "returns a new Rational number with 1 as the denominator" do
+        Rational(1).should.eql?(Rational(1, 1))
+        Rational(-3).should.eql?(Rational(-3, 1))
+        Rational(bignum_value).should.eql?(Rational(bignum_value, 1))
+      end
+    end
+  end
+
+  describe "passed two integers" do
+    it "returns a new Rational number" do
+      rat = Rational(1, 2)
+      rat.numerator.should == 1
+      rat.denominator.should == 2
+      rat.should.instance_of?(Rational)
+
+      rat = Rational(-3, -5)
+      rat.numerator.should == 3
+      rat.denominator.should == 5
+      rat.should.instance_of?(Rational)
+
+      rat = Rational(bignum_value, 3)
+      rat.numerator.should == bignum_value
+      rat.denominator.should == 3
+      rat.should.instance_of?(Rational)
+    end
+
+    it "reduces the Rational" do
+      rat = Rational(2, 4)
+      rat.numerator.should == 1
+      rat.denominator.should == 2
+
+      rat = Rational(3, 9)
+      rat.numerator.should == 1
+      rat.denominator.should == 3
+    end
+  end
+
+  describe "when passed a String" do
+    it "converts the String to a Rational using the same method as String#to_r" do
+      r = Rational(13, 25)
+      s_r = ".52".to_r
+      r_s = Rational(".52")
+
+      r_s.should == r
+      r_s.should == s_r
+    end
+
+    it "scales the Rational value of the first argument by the Rational value of the second" do
+      Rational(".52", ".6").should == Rational(13, 15)
+      Rational(".52", "1.6").should == Rational(13, 40)
+    end
+
+    it "does not use the same method as Float#to_r" do
+      r = Rational(3, 5)
+      f_r = 0.6.to_r
+      r_s = Rational("0.6")
+
+      r_s.should == r
+      r_s.should_not == f_r
+    end
+  end
+
+  describe "when passed a Numeric" do
+    it "calls #to_r to convert the first argument to a Rational" do
+      num = RationalSpecs::SubNumeric.new(2)
+
+      Rational(num).should == Rational(2)
+    end
+  end
+
+  describe "when passed a Complex" do
+    context "[Complex]" do
+      it "returns a Rational from the real part if the imaginary part is 0" do
+        Rational(Complex(1, 0)).should == Rational(1)
+      end
+
+      it "raises a RangeError if the imaginary part is not 0" do
+        -> { Rational(Complex(1, 2)) }.should.raise(RangeError, "can't convert 1+2i into Rational")
+      end
+    end
+
+    context "[Numeric, Complex]" do
+      it "uses the real part if the imaginary part is 0" do
+        Rational(1, Complex(2, 0)).should == Rational(1, 2)
+      end
+
+      it "divides a numerator by the Complex denominator if the imaginary part is not 0" do
+        Rational(1, Complex(2, 1)).should == Complex(2/5r, -1/5r)
+      end
+    end
+  end
+
+  context "when passed neither a Numeric nor a String" do
+    it "converts to Rational with #to_r method" do
+      obj = Object.new
+      def obj.to_r; 1/2r; end
+
+      Rational(obj).should == 1/2r
+    end
+
+    it "tries to convert to Integer with #to_int method if it does not respond to #to_r" do
+      obj = Object.new
+      def obj.to_int; 1; end
+
+      Rational(obj).should == 1r
+    end
+
+    it "raises TypeError if it neither responds to #to_r nor #to_int method" do
+      -> { Rational([]) }.should.raise(TypeError, "can't convert Array into Rational")
+      -> { Rational({}) }.should.raise(TypeError, "can't convert Hash into Rational")
+      -> { Rational(nil) }.should.raise(TypeError, "can't convert nil into Rational")
+    end
+
+    it "swallows exception raised in #to_int method" do
+      object = Object.new
+      def object.to_int() raise NoMethodError; end
+
+      -> { Rational(object) }.should.raise(TypeError)
+      -> { Rational(object, 1) }.should.raise(TypeError)
+      -> { Rational(1, object) }.should.raise(TypeError)
+    end
+
+    it "raises TypeError if #to_r does not return Rational" do
+      obj = Object.new
+      def obj.to_r; []; end
+
+      -> { Rational(obj) }.should raise_consistent_error(TypeError, "can't convert Object into Rational (Object#to_r gives Array)")
+    end
+  end
+
+  it "raises a ZeroDivisionError if the second argument is 0" do
+    -> { Rational(1, 0) }.should.raise(ZeroDivisionError, "divided by 0")
+    -> { Rational(1, 0.0) }.should.raise(ZeroDivisionError, "divided by 0")
+  end
+
+  it "raises a TypeError if the first argument is nil" do
+    -> { Rational(nil) }.should.raise(TypeError, "can't convert nil into Rational")
+  end
+
+  it "raises a TypeError if the second argument is nil" do
+    -> { Rational(1, nil) }.should.raise(TypeError, "can't convert nil into Rational")
+  end
+
+  it "raises a TypeError if the first argument is a Symbol" do
+    -> { Rational(:sym) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if the second argument is a Symbol" do
+    -> { Rational(1, :sym) }.should.raise(TypeError)
+  end
+
+  describe "when passed exception: false" do
+    describe "and [non-Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, exception: false).should == nil
+        Rational("abc", exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_r" do
+        obj = Object.new
+        def obj.to_r; raise; end
+        Rational(obj, exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_int" do
+        obj = Object.new
+        def obj.to_int; raise; end
+        Rational(obj, exception: false).should == nil
+      end
+    end
+
+    describe "and [non-Numeric, Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, 1, exception: false).should == nil
+        Rational("abc", 1, exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_r" do
+        obj = Object.new
+        def obj.to_r; raise; end
+        Rational(obj, 1, exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_int" do
+        obj = Object.new
+        def obj.to_int; raise; end
+        Rational(obj, 1, exception: false).should == nil
+      end
+    end
+
+    describe "and [anything, non-Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, :sym, exception: false).should == nil
+        Rational("abc", :sym, exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_r" do
+        obj = Object.new
+        def obj.to_r; raise; end
+        Rational(obj, obj, exception: false).should == nil
+      end
+
+      it "swallows an exception raised in #to_int" do
+        obj = Object.new
+        def obj.to_int; raise; end
+        Rational(obj, obj, exception: false).should == nil
+      end
+    end
+
+    describe "and non-Numeric String arguments" do
+      it "swallows an error" do
+        Rational("a", "b", exception: false).should == nil
+        Rational("a", 0, exception: false).should == nil
+        Rational(0, "b", exception: false).should == nil
+      end
+    end
+
+    describe "and nil arguments" do
+      it "swallows an error" do
+        Rational(nil, exception: false).should == nil
+        Rational(nil, nil, exception: false).should == nil
+      end
+    end
+  end
+
+  it "freezes its result" do
+    Rational(1).frozen?.should == true
+  end
 end
diff --git a/spec/ruby/core/kernel/String_spec.rb b/spec/ruby/core/kernel/String_spec.rb
index 47ee797be5..a9b0758ad7 100644
--- a/spec/ruby/core/kernel/String_spec.rb
+++ b/spec/ruby/core/kernel/String_spec.rb
@@ -32,7 +32,7 @@ describe :kernel_String, shared: true do
       undef_method :to_s
     end
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 
   # #5158
@@ -44,7 +44,7 @@ describe :kernel_String, shared: true do
       end
     end
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_s is not defined, even though #respond_to?(:to_s) returns true" do
@@ -57,7 +57,7 @@ describe :kernel_String, shared: true do
       end
     end
 
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 
   it "calls #to_s if #respond_to?(:to_s) returns true" do
@@ -74,14 +74,14 @@ describe :kernel_String, shared: true do
 
   it "raises a TypeError if #to_s does not return a String" do
     (obj = mock('123')).should_receive(:to_s).and_return(123)
-    -> { @object.send(@method, obj) }.should raise_error(TypeError)
+    -> { @object.send(@method, obj) }.should.raise(TypeError)
   end
 
   it "returns the same object if it is already a String" do
-    string = "Hello"
+    string = +"Hello"
     string.should_not_receive(:to_s)
     string2 = @object.send(@method, string)
-    string.should equal(string2)
+    string.should.equal?(string2)
   end
 
   it "returns the same object if it is an instance of a String subclass" do
@@ -89,7 +89,7 @@ describe :kernel_String, shared: true do
     string = subklass.new("Hello")
     string.should_not_receive(:to_s)
     string2 = @object.send(@method, string)
-    string.should equal(string2)
+    string.should.equal?(string2)
   end
 end
 
@@ -101,6 +101,6 @@ describe "Kernel#String" do
   it_behaves_like :kernel_String, :String, Object.new
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:String)
+    Kernel.private_instance_methods(false).should.include?(:String)
   end
 end
diff --git a/spec/ruby/core/kernel/__dir___spec.rb b/spec/ruby/core/kernel/__dir___spec.rb
index 3c34277277..242adbf48b 100644
--- a/spec/ruby/core/kernel/__dir___spec.rb
+++ b/spec/ruby/core/kernel/__dir___spec.rb
@@ -5,6 +5,13 @@ describe "Kernel#__dir__" do
     __dir__.should == File.realpath(File.dirname(__FILE__))
   end
 
+  it "returns the expanded path of the directory when used in the main script" do
+    fixtures_dir = File.dirname(fixture(__FILE__, '__dir__.rb'))
+    Dir.chdir(fixtures_dir) do
+      ruby_exe("__dir__.rb").should == "__dir__.rb\n#{fixtures_dir}\n"
+    end
+  end
+
   context "when used in eval with a given filename" do
     it "returns File.dirname(filename)" do
       eval("__dir__", nil, "foo.rb").should == "."
@@ -13,8 +20,8 @@ describe "Kernel#__dir__" do
   end
 
   context "when used in eval with top level binding" do
-    it "returns the real name of the directory containing the currently-executing file" do
-      eval("__dir__", binding).should == File.realpath(File.dirname(__FILE__))
+    it "returns nil" do
+      eval("__dir__", binding).should == nil
     end
   end
 end
diff --git a/spec/ruby/core/kernel/abort_spec.rb b/spec/ruby/core/kernel/abort_spec.rb
index f8152718c5..b75138182d 100644
--- a/spec/ruby/core/kernel/abort_spec.rb
+++ b/spec/ruby/core/kernel/abort_spec.rb
@@ -4,7 +4,7 @@ require_relative '../../shared/process/abort'
 
 describe "Kernel#abort" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:abort)
+    Kernel.private_instance_methods(false).should.include?(:abort)
   end
 
   it_behaves_like :process_abort, :abort, KernelSpecs::Method.new
diff --git a/spec/ruby/core/kernel/at_exit_spec.rb b/spec/ruby/core/kernel/at_exit_spec.rb
index 21149f965b..fdb0eaf34c 100644
--- a/spec/ruby/core/kernel/at_exit_spec.rb
+++ b/spec/ruby/core/kernel/at_exit_spec.rb
@@ -1,42 +1,17 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../shared/kernel/at_exit'
 
 describe "Kernel.at_exit" do
-  it "is a private method" do
-    Kernel.should have_private_instance_method(:at_exit)
-  end
-
-  it "runs after all other code" do
-    ruby_exe("at_exit {print 5}; print 6").should == "65"
-  end
-
-  it "runs in reverse order of registration" do
-    code = "at_exit {print 4};at_exit {print 5}; print 6; at_exit {print 7}"
-    ruby_exe(code).should == "6754"
-  end
+  it_behaves_like :kernel_at_exit, :at_exit
 
-  it "allows calling exit inside at_exit handler" do
-    code = "at_exit {print 3}; at_exit {print 4; exit; print 5}; at_exit {print 6}"
-    ruby_exe(code).should == "643"
+  it "is a private method" do
+    Kernel.private_instance_methods(false).should.include?(:at_exit)
   end
 
-  it "gives access to the last raised exception" do
-    code = <<-EOC
-      at_exit do
-        puts "The exception matches: \#{$! == $exception}"
-      end
-
-      begin
-        raise "foo"
-      rescue => $exception
-        raise
-      end
-    EOC
-
-    result = ruby_exe(code, args: "2>&1", escape: true)
-    result.should =~ /The exception matches: true/
+  it "raises ArgumentError if called without a block" do
+    -> { at_exit }.should.raise(ArgumentError, "called without a block")
   end
-
 end
 
 describe "Kernel#at_exit" do
diff --git a/spec/ruby/core/kernel/autoload_relative_spec.rb b/spec/ruby/core/kernel/autoload_relative_spec.rb
new file mode 100644
index 0000000000..7d03da8a40
--- /dev/null
+++ b/spec/ruby/core/kernel/autoload_relative_spec.rb
@@ -0,0 +1,114 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# Specs for Kernel#autoload_relative
+
+ruby_version_is "4.1" do
+  describe "Kernel#autoload_relative" do
+    before :each do
+      @loaded_features = $".dup
+    end
+
+    after :each do
+      $".replace @loaded_features
+      # Clean up constants defined by these tests
+      [:KSAutoloadRelativeA, :KSAutoloadRelativeB, :KSAutoloadRelativeC,
+       :KSAutoloadRelativeE, :KSAutoloadRelativeF, :KSAutoloadRelativeG,
+       :KSAutoloadRelativeH, :KSAutoloadRelativeI].each do |const|
+        KernelSpecs.send(:remove_const, const) if KernelSpecs.const_defined?(const, false)
+      end
+      [:KSAutoloadRelativeD, :NestedTest].each do |const|
+        Object.send(:remove_const, const) if Object.const_defined?(const, false)
+      end
+    end
+
+    it "is a private method" do
+      Kernel.private_instance_methods(false).should.include?(:autoload_relative)
+    end
+
+    it "registers a file to load relative to the current file" do
+      KernelSpecs.autoload_relative :KSAutoloadRelativeA, "fixtures/autoload_relative_b.rb"
+      path = KernelSpecs.autoload?(:KSAutoloadRelativeA)
+      path.should_not == nil
+      path.should.end_with?("autoload_relative_b.rb")
+      File.exist?(path).should == true
+    end
+
+    it "loads the file when the constant is accessed" do
+      KernelSpecs.autoload_relative :KSAutoloadRelativeB, "fixtures/autoload_relative_b.rb"
+      KernelSpecs::KSAutoloadRelativeB.loaded.should == :ksautoload_b
+    end
+
+    it "sets the autoload constant in the constant table" do
+      KernelSpecs.autoload_relative :KSAutoloadRelativeC, "fixtures/autoload_relative_b.rb"
+      KernelSpecs.should.const_defined?(:KSAutoloadRelativeC, false)
+    end
+
+    it "can autoload in instance_eval with a file context" do
+      result = Object.new.instance_eval(<<-CODE, __FILE__, __LINE__)
+        autoload_relative :KSAutoloadRelativeD, "fixtures/autoload_relative_d.rb"
+        KSAutoloadRelativeD.loaded
+      CODE
+      result.should == :ksautoload_d
+    end
+
+    it "raises LoadError if called from eval without file context" do
+      -> {
+        eval('autoload_relative :Foo, "foo.rb"')
+      }.should.raise(LoadError, /autoload_relative called without file context/)
+    end
+
+    it "accepts both string and symbol for constant name" do
+      KernelSpecs.autoload_relative :KSAutoloadRelativeE, "fixtures/autoload_relative_b.rb"
+      KernelSpecs.autoload_relative "KSAutoloadRelativeF", "fixtures/autoload_relative_b.rb"
+
+      KernelSpecs.should.const_defined?(:KSAutoloadRelativeE, false)
+      KernelSpecs.should.const_defined?(:KSAutoloadRelativeF, false)
+    end
+
+    it "returns nil" do
+      KernelSpecs.autoload_relative(:KSAutoloadRelativeG, "fixtures/autoload_relative_b.rb").should == nil
+    end
+
+    it "resolves nested directory paths correctly" do
+      -> {
+        autoload_relative :NestedTest, "../kernel/fixtures/autoload_relative_b.rb"
+        autoload?(:NestedTest)
+      }.should_not.raise
+    end
+
+    it "resolves paths starting with ./" do
+      KernelSpecs.autoload_relative :KSAutoloadRelativeH, "./fixtures/autoload_relative_b.rb"
+      path = KernelSpecs.autoload?(:KSAutoloadRelativeH)
+      path.should_not == nil
+      path.should.end_with?("autoload_relative_b.rb")
+    end
+
+    it "ignores $LOAD_PATH and uses only relative path resolution" do
+      original_load_path = $LOAD_PATH.dup
+      $LOAD_PATH.clear
+      begin
+        KernelSpecs.autoload_relative :KSAutoloadRelativeI, "fixtures/autoload_relative_b.rb"
+        path = KernelSpecs.autoload?(:KSAutoloadRelativeI)
+        path.should_not == nil
+        # Should still resolve even with empty $LOAD_PATH
+        File.exist?(path).should == true
+      ensure
+        $LOAD_PATH.replace(original_load_path)
+      end
+    end
+
+    describe "when Object is frozen" do
+      it "raises a FrozenError before defining the constant" do
+        ruby_exe(<<-RUBY).should.include?("FrozenError")
+          Object.freeze
+          begin
+            autoload_relative :Foo, "autoload_b.rb"
+          rescue => e
+            puts e.class
+          end
+        RUBY
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/kernel/autoload_spec.rb b/spec/ruby/core/kernel/autoload_spec.rb
index 68732a69ef..46783734c4 100644
--- a/spec/ruby/core/kernel/autoload_spec.rb
+++ b/spec/ruby/core/kernel/autoload_spec.rb
@@ -7,7 +7,9 @@ require_relative 'fixtures/classes'
 
 autoload :KSAutoloadA, "autoload_a.rb"
 autoload :KSAutoloadB, fixture(__FILE__, "autoload_b.rb")
-autoload :KSAutoloadCallsRequire, "main_autoload_not_exist.rb"
+define_autoload_KSAutoloadCallsRequire = -> {
+  autoload :KSAutoloadCallsRequire, "main_autoload_not_exist.rb"
+}
 
 def check_autoload(const)
   autoload? const
@@ -23,7 +25,7 @@ describe "Kernel#autoload" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:autoload)
+    Kernel.private_instance_methods(false).should.include?(:autoload)
   end
 
   it "registers a file to load the first time the named constant is accessed" do
@@ -35,7 +37,7 @@ describe "Kernel#autoload" do
   end
 
   it "sets the autoload constant in Object's constant table" do
-    Object.should have_constant(:KSAutoloadA)
+    Object.should.const_defined?(:KSAutoloadA, false)
   end
 
   it "loads the file when the constant is accessed" do
@@ -43,10 +45,11 @@ describe "Kernel#autoload" do
   end
 
   it "calls main.require(path) to load the file" do
+    define_autoload_KSAutoloadCallsRequire.call
     main = TOPLEVEL_BINDING.eval("self")
     main.should_receive(:require).with("main_autoload_not_exist.rb")
     # The constant won't be defined since require is mocked to do nothing
-    -> { KSAutoloadCallsRequire }.should raise_error(NameError)
+    -> { KSAutoloadCallsRequire }.should.raise(NameError)
   end
 
   it "can autoload in instance_eval" do
@@ -56,9 +59,24 @@ describe "Kernel#autoload" do
     end
   end
 
+  describe "inside a Class.new method body" do
+    # NOTE: this spec is being discussed in https://github.com/ruby/spec/pull/839
+    it "should define on the new anonymous class" do
+      cls = Class.new do
+        def go
+          autoload :Object, 'bogus'
+          autoload? :Object
+        end
+      end
+
+      cls.new.go.should == 'bogus'
+      cls.autoload?(:Object).should == 'bogus'
+    end
+  end
+
   describe "when Object is frozen" do
-    it "raises a #{frozen_error_class} before defining the constant" do
-      ruby_exe(fixture(__FILE__, "autoload_frozen.rb")).should == "#{frozen_error_class} - nil"
+    it "raises a FrozenError before defining the constant" do
+      ruby_exe(fixture(__FILE__, "autoload_frozen.rb")).should == "FrozenError - nil"
     end
   end
 
@@ -84,7 +102,7 @@ end
 
 describe "Kernel#autoload?" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:autoload?)
+    Kernel.private_instance_methods(false).should.include?(:autoload?)
   end
 
   it "returns the name of the file that will be autoloaded" do
@@ -92,7 +110,7 @@ describe "Kernel#autoload?" do
   end
 
   it "returns nil if no file has been registered for a constant" do
-    check_autoload(:Manualload).should be_nil
+    check_autoload(:Manualload).should == nil
   end
 end
 
@@ -119,7 +137,7 @@ describe "Kernel.autoload" do
   end
 
   it "sets the autoload constant in Object's constant table" do
-    Object.should have_constant(:KSAutoloadBB)
+    Object.should.const_defined?(:KSAutoloadBB, false)
   end
 
   it "calls #to_path on non-String filenames" do
@@ -155,6 +173,6 @@ describe "Kernel.autoload?" do
   end
 
   it "returns nil if no file has been registered for a constant" do
-    Kernel.autoload?(:Manualload).should be_nil
+    Kernel.autoload?(:Manualload).should == nil
   end
 end
diff --git a/spec/ruby/core/kernel/backtick_spec.rb b/spec/ruby/core/kernel/backtick_spec.rb
index 5ab0fb0eea..42e0f975f5 100644
--- a/spec/ruby/core/kernel/backtick_spec.rb
+++ b/spec/ruby/core/kernel/backtick_spec.rb
@@ -11,7 +11,7 @@ describe "Kernel#`" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:`)
+    Kernel.private_instance_methods(false).should.include?(:`)
   end
 
   it "returns the standard output of the executed sub-process" do
@@ -28,28 +28,32 @@ describe "Kernel#`" do
 
   it "produces a String in the default external encoding" do
     Encoding.default_external = Encoding::SHIFT_JIS
-    `echo disc`.encoding.should equal(Encoding::SHIFT_JIS)
+    `echo disc`.encoding.should.equal?(Encoding::SHIFT_JIS)
   end
 
   it "raises an Errno::ENOENT if the command is not executable" do
-    -> { `nonexistent_command` }.should raise_error(Errno::ENOENT)
+    -> { `nonexistent_command` }.should.raise(Errno::ENOENT)
   end
 
   platform_is_not :windows do
+    it "handles invalid UTF-8 bytes in command" do
+      `echo "testing\xC2 a non UTF-8 string"`.b.should == "testing\xC2 a non UTF-8 string\n".b
+    end
+
     it "sets $? to the exit status of the executed sub-process" do
       ip = 'world'
       `echo disc #{ip}`
-      $?.should be_kind_of(Process::Status)
-      $?.stopped?.should == false
-      $?.exited?.should == true
+      $?.should.is_a?(Process::Status)
+      $?.should_not.stopped?
+      $?.should.exited?
       $?.exitstatus.should == 0
-      $?.success?.should == true
+      $?.should.success?
       `echo disc #{ip}; exit 99`
-      $?.should be_kind_of(Process::Status)
-      $?.stopped?.should == false
-      $?.exited?.should == true
+      $?.should.is_a?(Process::Status)
+      $?.should_not.stopped?
+      $?.should.exited?
       $?.exitstatus.should == 99
-      $?.success?.should == false
+      $?.should_not.success?
     end
   end
 
@@ -57,17 +61,17 @@ describe "Kernel#`" do
     it "sets $? to the exit status of the executed sub-process" do
       ip = 'world'
       `echo disc #{ip}`
-      $?.should be_kind_of(Process::Status)
-      $?.stopped?.should == false
-      $?.exited?.should == true
+      $?.should.is_a?(Process::Status)
+      $?.should_not.stopped?
+      $?.should.exited?
       $?.exitstatus.should == 0
-      $?.success?.should == true
+      $?.should.success?
       `echo disc #{ip}& exit 99`
-      $?.should be_kind_of(Process::Status)
-      $?.stopped?.should == false
-      $?.exited?.should == true
+      $?.should.is_a?(Process::Status)
+      $?.should_not.stopped?
+      $?.should.exited?
       $?.exitstatus.should == 99
-      $?.success?.should == false
+      $?.should_not.success?
     end
   end
 end
diff --git a/spec/ruby/core/kernel/binding_spec.rb b/spec/ruby/core/kernel/binding_spec.rb
index f1c9c6ec9f..6f27b26f37 100644
--- a/spec/ruby/core/kernel/binding_spec.rb
+++ b/spec/ruby/core/kernel/binding_spec.rb
@@ -9,7 +9,7 @@ end
 
 describe "Kernel#binding" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:binding)
+    Kernel.private_instance_methods(false).should.include?(:binding)
   end
 
   before :each do
@@ -35,7 +35,7 @@ describe "Kernel#binding" do
   end
 
   it "raises a NameError on undefined variable" do
-    -> { eval("a_fake_variable", @b1) }.should raise_error(NameError)
+    -> { eval("a_fake_variable", @b1) }.should.raise(NameError)
   end
 
   it "uses the closure's self as self in the binding" do
diff --git a/spec/ruby/core/kernel/block_given_spec.rb b/spec/ruby/core/kernel/block_given_spec.rb
index b00bfabfc3..20bb90ae96 100644
--- a/spec/ruby/core/kernel/block_given_spec.rb
+++ b/spec/ruby/core/kernel/block_given_spec.rb
@@ -5,15 +5,20 @@ describe :kernel_block_given, shared: true do
   it "returns true if and only if a block is supplied" do
     @object.accept_block {}.should == true
     @object.accept_block_as_argument {}.should == true
+    @object.accept_block_inside_block {}.should == true
+    @object.accept_block_as_argument_inside_block {}.should == true
 
     @object.accept_block.should == false
     @object.accept_block_as_argument.should == false
+    @object.accept_block_inside_block.should == false
+    @object.accept_block_as_argument_inside_block.should == false
   end
 
   # Clarify: Based on http://www.ruby-forum.com/topic/137822 it appears
   # that Matz wanted this to be true in 1.9.
   it "returns false when a method defined by define_method is called with a block" do
     @object.defined_block {}.should == false
+    @object.defined_block_inside_block {}.should == false
   end
 end
 
@@ -25,7 +30,7 @@ describe "Kernel#block_given?" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:block_given?)
+    Kernel.private_instance_methods(false).should.include?(:block_given?)
   end
 end
 
diff --git a/spec/ruby/core/kernel/caller_locations_spec.rb b/spec/ruby/core/kernel/caller_locations_spec.rb
index 4de6c2ffd6..04cf806ef4 100644
--- a/spec/ruby/core/kernel/caller_locations_spec.rb
+++ b/spec/ruby/core/kernel/caller_locations_spec.rb
@@ -3,11 +3,11 @@ require_relative 'fixtures/caller_locations'
 
 describe 'Kernel#caller_locations' do
   it 'is a private method' do
-    Kernel.should have_private_instance_method(:caller_locations)
+    Kernel.private_instance_methods(false).should.include?(:caller_locations)
   end
 
   it 'returns an Array of caller locations' do
-    KernelSpecs::CallerLocationsTest.locations.empty?.should == false
+    KernelSpecs::CallerLocationsTest.locations.should_not.empty?
   end
 
   it 'returns an Array of caller locations using a custom offset' do
@@ -22,6 +22,42 @@ describe 'Kernel#caller_locations' do
     locations.length.should == 1
   end
 
+  it "can be called with a range" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(2..4)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "works with endless ranges" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(eval("(2..)"))
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+  end
+
+  it "works with beginless ranges" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations((...5))
+    locations2.map(&:to_s)[eval("(2..)")].should == locations1[(...5)].map(&:to_s)[eval("(2..)")]
+  end
+
+  it "can be called with a range whose end is negative" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(2..-1)
+    locations3 = caller_locations(2..-2)
+    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+    locations1[2..-2].map(&:to_s).should == locations3.map(&:to_s)
+  end
+
+  it "must return nil if omitting more locations than available" do
+    caller_locations(100).should == nil
+    caller_locations(100..-1).should == nil
+  end
+
+  it "must return [] if omitting exactly the number of locations available" do
+    omit = caller_locations(0).length
+    caller_locations(omit).should == []
+  end
+
   it 'returns the locations as Thread::Backtrace::Location instances' do
     locations = KernelSpecs::CallerLocationsTest.locations
 
@@ -29,4 +65,49 @@ describe 'Kernel#caller_locations' do
       location.kind_of?(Thread::Backtrace::Location).should == true
     end
   end
+
+  it "must return the same locations when called with 1..-1 and when called with no arguments" do
+    caller_locations.map(&:to_s).should == caller_locations(1..-1).map(&:to_s)
+  end
+
+  guard -> { Kernel.instance_method(:tap).source_location } do
+    ruby_version_is ""..."3.4" do
+      it "includes core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller_locations(1, 1)[0] }
+        loc.label.should == "tap"
+        loc.path.should.start_with? "<internal:"
+      end
+    end
+
+    ruby_version_is "3.4"..."4.0" do
+      it "includes core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller_locations(1, 1)[0] }
+        loc.label.should == "Kernel#tap"
+        loc.path.should.start_with? "<internal:"
+      end
+    end
+
+    ruby_version_is "4.0" do
+      it "does not include core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller_locations(1, 1)[0] }
+        loc.label.should == "Kernel#tap"
+        # CRuby hides the file which defines the method: https://bugs.ruby-lang.org/issues/20968
+        unless loc.path == __FILE__
+          loc.path.should.start_with? "<internal:"
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/caller_spec.rb b/spec/ruby/core/kernel/caller_spec.rb
index 8469319c94..225f6fc458 100644
--- a/spec/ruby/core/kernel/caller_spec.rb
+++ b/spec/ruby/core/kernel/caller_spec.rb
@@ -3,11 +3,11 @@ require_relative 'fixtures/caller'
 
 describe 'Kernel#caller' do
   it 'is a private method' do
-    Kernel.should have_private_instance_method(:caller)
+    Kernel.private_instance_methods(false).should.include?(:caller)
   end
 
   it 'returns an Array of caller locations' do
-    KernelSpecs::CallerTest.locations.empty?.should == false
+    KernelSpecs::CallerTest.locations.should_not.empty?
   end
 
   it 'returns an Array of caller locations using a custom offset' do
@@ -32,15 +32,90 @@ describe 'Kernel#caller' do
     locations = KernelSpecs::CallerTest.locations
     line      = __LINE__ - 1
 
-    locations[0].should include("#{__FILE__}:#{line}:in")
+    locations[0].should.include?("#{__FILE__}:#{line}:in")
   end
 
   it "returns an Array with the block given to #at_exit at the base of the stack" do
     path = fixture(__FILE__, "caller_at_exit.rb")
     lines = ruby_exe(path).lines
-    lines.should == [
-      "#{path}:6:in `foo'\n",
-      "#{path}:2:in `block in <main>'\n"
-    ]
+    lines.size.should == 2
+    lines[0].should =~ /\A#{path}:6:in [`'](?:Object#)?foo'\n\z/
+    lines[1].should =~ /\A#{path}:2:in [`']block in <main>'\n\z/
+  end
+
+  it "can be called with a range" do
+    locations1 = caller(0)
+    locations2 = caller(2..4)
+    locations1[2..4].should == locations2
+  end
+
+  it "works with endless ranges" do
+    locations1 = KernelSpecs::CallerTest.locations(0)
+    locations2 = KernelSpecs::CallerTest.locations(eval("(2..)"))
+    locations2.should == locations1[2..-1]
+  end
+
+  it "works with beginless ranges" do
+    locations1 = KernelSpecs::CallerTest.locations(0)
+    locations2 = KernelSpecs::CallerTest.locations((..5))
+    locations2[eval("(2..)")].should == locations1[(..5)][eval("(2..)")]
+  end
+
+  it "can be called with a range whose end is negative" do
+    locations1 = caller(0)
+    locations2 = caller(2..-1)
+    locations3 = caller(2..-2)
+    locations1[2..-1].should == locations2
+    locations1[2..-2].should == locations3
+  end
+
+  it "must return nil if omitting more locations than available" do
+    caller(100).should == nil
+    caller(100..-1).should == nil
+  end
+
+  it "must return [] if omitting exactly the number of locations available" do
+    omit = caller(0).length
+    caller(omit).should == []
+  end
+
+  it "must return the same locations when called with 1..-1 and when called with no arguments" do
+    caller.should == caller(1..-1)
+  end
+
+  guard -> { Kernel.instance_method(:tap).source_location } do
+    ruby_version_is ""..."3.4" do
+      it "includes core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller(1, 1)[0] }
+        loc.should =~ /\A<internal:.*in `tap'\z/
+      end
+    end
+
+    ruby_version_is "3.4"..."4.0" do
+      it "includes core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller(1, 1)[0] }
+        loc.should =~ /\A<internal:.*in 'Kernel#tap'\z/
+      end
+    end
+
+    ruby_version_is "4.0" do
+      it "does not include core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
+
+        loc = nil
+        tap { loc = caller(1, 1)[0] }
+        # CRuby hides the file which defines the method: https://bugs.ruby-lang.org/issues/20968
+        loc.should =~ /\A(<internal:|#{__FILE__}:).*in 'Kernel#tap'\z/
+      end
+    end
   end
 end
diff --git a/spec/ruby/core/kernel/case_compare_spec.rb b/spec/ruby/core/kernel/case_compare_spec.rb
index b8d30960e8..c74bbf63b9 100644
--- a/spec/ruby/core/kernel/case_compare_spec.rb
+++ b/spec/ruby/core/kernel/case_compare_spec.rb
@@ -58,18 +58,18 @@ describe "Kernel#=== for a class with #== overridden to consider other object's
   end
 
   it "returns true if #== returns true even if #equal? is false" do
-    @o1.should_not equal(@o2)
+    @o1.should_not.equal?(@o2)
     (@o1 == @o2).should == true
     (@o1 === @o2).should == true
   end
 
   it "returns true if #equal? returns true" do
-    @o1.should equal(@o1)
+    @o1.should.equal?(@o1)
     (@o1 === @o1).should == true
   end
 
   it "returns false if neither #== nor #equal? returns true" do
-    @o1.should_not equal(@o)
+    @o1.should_not.equal?(@o)
     (@o1 == @o).should == false
     (@o1 === @o).should == false
   end
@@ -83,13 +83,13 @@ describe "Kernel#=== for a class with #equal? overridden to always be false" do
   end
 
   it "returns true if #== returns true even if #equal? is false" do
-    @o1.should_not equal(@o1)
+    @o1.should_not.equal?(@o1)
     (@o1 == @o1).should == true
     (@o1 === @o1).should == true
   end
 
   it "returns false if neither #== nor #equal? returns true" do
-    @o1.should_not equal(@o)
+    @o1.should_not.equal?(@o)
     (@o1 == @o).should == false
     (@o1 === @o).should == false
   end
@@ -105,7 +105,7 @@ describe "Kernel#=== for a class with #== and #equal? overridden to always be fa
   it "returns true if the object id is the same even if both #== and #equal? return false" do
     @o1.object_id.should == @o1.object_id
 
-    @o1.should_not equal(@o1)
+    @o1.should_not.equal?(@o1)
     (@o1 == @o1).should == false
 
     (@o1 === @o1).should == true
@@ -114,7 +114,7 @@ describe "Kernel#=== for a class with #== and #equal? overridden to always be fa
   it "returns false if the object id is not the same and both #== and #equal? return false" do
     @o1.object_id.should_not == @o2.object_id
 
-    @o1.should_not equal(@o2)
+    @o1.should_not.equal?(@o2)
     (@o1 == @o2).should == false
 
     (@o1 === @o2).should == false
diff --git a/spec/ruby/core/kernel/catch_spec.rb b/spec/ruby/core/kernel/catch_spec.rb
index 4060172429..9f02303678 100644
--- a/spec/ruby/core/kernel/catch_spec.rb
+++ b/spec/ruby/core/kernel/catch_spec.rb
@@ -31,11 +31,11 @@ describe "Kernel.catch" do
   end
 
   it "raises an ArgumentError if a Symbol is thrown for a String catch value" do
-    -> { catch("exit") { throw :exit } }.should raise_error(ArgumentError)
+    -> { catch("exit") { throw :exit } }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if a String with different identity is thrown" do
-    -> { catch("exit") { throw "exit" } }.should raise_error(ArgumentError)
+    -> { catch("exit".dup) { throw "exit".dup } }.should.raise(ArgumentError)
   end
 
   it "catches a Symbol when thrown a matching Symbol" do
@@ -60,7 +60,7 @@ describe "Kernel.catch" do
   end
 
   it "yields an object when called without arguments" do
-    catch { |tag| tag }.should be_an_instance_of(Object)
+    catch { |tag| tag }.should.instance_of?(Object)
   end
 
   it "can be used even in a method different from where throw is called" do
@@ -116,12 +116,12 @@ describe "Kernel.catch" do
   end
 
   it "raises LocalJumpError if no block is given" do
-    -> { catch :blah }.should raise_error(LocalJumpError)
+    -> { catch :blah }.should.raise(LocalJumpError)
   end
 end
 
 describe "Kernel#catch" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:catch)
+    Kernel.private_instance_methods(false).should.include?(:catch)
   end
 end
diff --git a/spec/ruby/core/kernel/chomp_spec.rb b/spec/ruby/core/kernel/chomp_spec.rb
index d30e77c35a..434bf652f9 100644
--- a/spec/ruby/core/kernel/chomp_spec.rb
+++ b/spec/ruby/core/kernel/chomp_spec.rb
@@ -26,7 +26,7 @@ end
 
 describe :kernel_chomp_private, shared: true do
   it "is a private method" do
-    KernelSpecs.has_private_method(@method).should be_true
+    KernelSpecs.has_private_method(@method).should == true
   end
 end
 
diff --git a/spec/ruby/core/kernel/chop_spec.rb b/spec/ruby/core/kernel/chop_spec.rb
index 9b91c011bc..bbf3c3f724 100644
--- a/spec/ruby/core/kernel/chop_spec.rb
+++ b/spec/ruby/core/kernel/chop_spec.rb
@@ -14,7 +14,7 @@ end
 
 describe :kernel_chop_private, shared: true do
   it "is a private method" do
-    KernelSpecs.has_private_method(@method).should be_true
+    KernelSpecs.has_private_method(@method).should == true
   end
 end
 
diff --git a/spec/ruby/core/kernel/class_spec.rb b/spec/ruby/core/kernel/class_spec.rb
index 4d3b4e549b..0a7f774d14 100644
--- a/spec/ruby/core/kernel/class_spec.rb
+++ b/spec/ruby/core/kernel/class_spec.rb
@@ -3,24 +3,24 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#class" do
   it "returns the class of the object" do
-    Object.new.class.should equal(Object)
+    Object.new.class.should.equal?(Object)
 
-    1.class.should equal(Fixnum)
-    3.14.class.should equal(Float)
-    :hello.class.should equal(Symbol)
-    "hello".class.should equal(String)
-    [1, 2].class.should equal(Array)
-    { 1 => 2 }.class.should equal(Hash)
+    1.class.should.equal?(Integer)
+    3.14.class.should.equal?(Float)
+    :hello.class.should.equal?(Symbol)
+    "hello".class.should.equal?(String)
+    [1, 2].class.should.equal?(Array)
+    { 1 => 2 }.class.should.equal?(Hash)
   end
 
   it "returns Class for a class" do
-    BasicObject.class.should equal(Class)
-    String.class.should equal(Class)
+    BasicObject.class.should.equal?(Class)
+    String.class.should.equal?(Class)
   end
 
   it "returns the first non-singleton class" do
-    a = "hello"
+    a = +"hello"
     def a.my_singleton_method; end
-    a.class.should equal(String)
+    a.class.should.equal?(String)
   end
 end
diff --git a/spec/ruby/core/kernel/clone_spec.rb b/spec/ruby/core/kernel/clone_spec.rb
index eb8739d571..4ddb23d6e6 100644
--- a/spec/ruby/core/kernel/clone_spec.rb
+++ b/spec/ruby/core/kernel/clone_spec.rb
@@ -25,24 +25,91 @@ describe "Kernel#clone" do
     end
 
     clone = instance.clone
-    clone.class.should equal klass
+    clone.class.should.equal? klass
   end
 
-  it "copies frozen state from the original" do
-    o2 = @obj.clone
-    @obj.freeze
-    o3 = @obj.clone
+  describe "with no arguments" do
+    it "copies frozen state from the original" do
+      o2 = @obj.clone
+      o2.should_not.frozen?
 
-    o2.frozen?.should == false
-    o3.frozen?.should == true
+      @obj.freeze
+      o3 = @obj.clone
+      o3.should.frozen?
+    end
+
+    it 'copies frozen?' do
+      o = ''.freeze.clone
+      o.frozen?.should == true
+    end
+  end
+
+  describe "with freeze: nil" do
+    it "copies frozen state from the original, like #clone without arguments" do
+      o2 = @obj.clone(freeze: nil)
+      o2.should_not.frozen?
+
+      @obj.freeze
+      o3 = @obj.clone(freeze: nil)
+      o3.should.frozen?
+    end
+
+    it "copies frozen?" do
+      o = "".freeze.clone(freeze: nil)
+      o.frozen?.should == true
+    end
+  end
+
+  describe "with freeze: true" do
+    it 'makes a frozen copy if the original is frozen' do
+      @obj.freeze
+      @obj.clone(freeze: true).should.frozen?
+    end
+
+    it 'freezes the copy even if the original was not frozen' do
+      @obj.clone(freeze: true).should.frozen?
+    end
+
+    it "calls #initialize_clone with kwargs freeze: true" do
+      obj = KernelSpecs::CloneFreeze.new
+      obj.clone(freeze: true)
+      ScratchPad.recorded.should == [obj, { freeze: true }]
+    end
+
+    it "calls #initialize_clone with kwargs freeze: true even if #initialize_clone only takes a single argument" do
+      obj = KernelSpecs::Clone.new
+      -> { obj.clone(freeze: true) }.should.raise(ArgumentError, 'wrong number of arguments (given 2, expected 1)')
+    end
   end
 
-  it 'takes an option to copy freeze state or not' do
-    @obj.clone(freeze: true).frozen?.should == false
-    @obj.clone(freeze: false).frozen?.should == false
-    @obj.freeze
-    @obj.clone(freeze: true).frozen?.should == true
-    @obj.clone(freeze: false).frozen?.should == false
+  describe "with freeze: false" do
+    it 'does not freeze the copy if the original is frozen' do
+      @obj.freeze
+      @obj.clone(freeze: false).should_not.frozen?
+    end
+
+    it 'does not freeze the copy if the original is not frozen' do
+      @obj.clone(freeze: false).should_not.frozen?
+    end
+
+    it "calls #initialize_clone with kwargs freeze: false" do
+      obj = KernelSpecs::CloneFreeze.new
+      obj.clone(freeze: false)
+      ScratchPad.recorded.should == [obj, { freeze: false }]
+    end
+
+    it "calls #initialize_clone with kwargs freeze: false even if #initialize_clone only takes a single argument" do
+      obj = KernelSpecs::Clone.new
+      -> { obj.clone(freeze: false) }.should.raise(ArgumentError, 'wrong number of arguments (given 2, expected 1)')
+    end
+  end
+
+  describe "with freeze: anything else" do
+    it 'raises ArgumentError when passed not true/false/nil' do
+      -> { @obj.clone(freeze: 1) }.should.raise(ArgumentError, /unexpected value for freeze: Integer/)
+      -> { @obj.clone(freeze: "") }.should.raise(ArgumentError, /unexpected value for freeze: String/)
+      -> { @obj.clone(freeze: Object.new) }.should.raise(ArgumentError, /unexpected value for freeze: Object/)
+    end
   end
 
   it "copies instance variables" do
@@ -107,10 +174,4 @@ describe "Kernel#clone" do
 
     cloned.bar.should == ['a']
   end
-
-  it 'copies frozen? and tainted?' do
-    o = ''.taint.freeze.clone
-    o.frozen?.should be_true
-    o.tainted?.should be_true
-  end
 end
diff --git a/spec/ruby/core/kernel/comparison_spec.rb b/spec/ruby/core/kernel/comparison_spec.rb
index affdc5c00d..48f17e1172 100644
--- a/spec/ruby/core/kernel/comparison_spec.rb
+++ b/spec/ruby/core/kernel/comparison_spec.rb
@@ -15,17 +15,17 @@ describe "Kernel#<=>" do
   it "returns nil if self is eql? but not == to the argument" do
     obj = mock('has eql?')
     obj.should_not_receive(:eql?)
-    obj.<=>(Object.new).should be_nil
+    obj.<=>(Object.new).should == nil
   end
 
   it "returns nil if self.==(arg) returns nil" do
     obj = mock('wrong ==')
     obj.should_receive(:==).and_return(nil)
-    obj.<=>(Object.new).should be_nil
+    obj.<=>(Object.new).should == nil
   end
 
   it "returns nil if self is not == to the argument" do
     obj = Object.new
-    obj.<=>(3.14).should be_nil
+    obj.<=>(3.14).should == nil
   end
 end
diff --git a/spec/ruby/core/kernel/define_singleton_method_spec.rb b/spec/ruby/core/kernel/define_singleton_method_spec.rb
index dc77c3e6f8..ec48581db8 100644
--- a/spec/ruby/core/kernel/define_singleton_method_spec.rb
+++ b/spec/ruby/core/kernel/define_singleton_method_spec.rb
@@ -14,14 +14,14 @@ describe "Kernel#define_singleton_method" do
     end
 
     it "adds the new method to the methods list" do
-      DefineSingletonMethodSpecClass.should have_method(:another_test_method)
+      DefineSingletonMethodSpecClass.should.respond_to?(:another_test_method)
     end
 
     it "defines any Child class method from any Parent's class methods" do
       um = KernelSpecs::Parent.method(:parent_class_method).unbind
       KernelSpecs::Child.send :define_singleton_method, :child_class_method, um
       KernelSpecs::Child.child_class_method.should == :foo
-      ->{KernelSpecs::Parent.child_class_method}.should raise_error(NoMethodError)
+      ->{KernelSpecs::Parent.child_class_method}.should.raise(NoMethodError)
     end
 
     it "will raise when attempting to define an object's singleton method from another object's singleton method" do
@@ -33,7 +33,7 @@ describe "Kernel#define_singleton_method" do
         end
       end
       um = p.method(:singleton_method).unbind
-      ->{ other.send :define_singleton_method, :other_singleton_method, um }.should raise_error(TypeError)
+      ->{ other.send :define_singleton_method, :other_singleton_method, um }.should.raise(TypeError)
     end
 
   end
@@ -52,11 +52,11 @@ describe "Kernel#define_singleton_method" do
   it "raises a TypeError when the given method is no Method/Proc" do
     -> {
       Class.new { define_singleton_method(:test, "self") }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
 
     -> {
       Class.new { define_singleton_method(:test, 1234) }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "defines a new singleton method for objects" do
@@ -65,7 +65,7 @@ describe "Kernel#define_singleton_method" do
     obj.test.should == "world!"
     -> {
       Object.new.test
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   it "maintains the Proc's scope" do
@@ -83,7 +83,7 @@ describe "Kernel#define_singleton_method" do
     obj = Object.new
     -> {
       obj.define_singleton_method(:test)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "does not use the caller block when no block is given" do
@@ -94,6 +94,27 @@ describe "Kernel#define_singleton_method" do
 
     -> {
       o.define(:foo) { raise "not used" }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
+  end
+
+  it "always defines the method with public visibility" do
+    cls = Class.new
+    def cls.define(name, &block)
+      private
+      define_singleton_method(name, &block)
+    end
+
+    -> {
+      suppress_warning do
+        cls.define(:foo) { :ok }
+      end
+      cls.foo.should == :ok
+    }.should_not.raise(NoMethodError)
+  end
+
+  it "cannot define a singleton method with a frozen singleton class" do
+    o = Object.new
+    o.freeze
+    -> { o.define_singleton_method(:foo) { 1 } }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/kernel/dup_spec.rb b/spec/ruby/core/kernel/dup_spec.rb
index fe0a269d69..99de5e3732 100644
--- a/spec/ruby/core/kernel/dup_spec.rb
+++ b/spec/ruby/core/kernel/dup_spec.rb
@@ -25,14 +25,14 @@ describe "Kernel#dup" do
     end
 
     dup = instance.dup
-    dup.class.should equal klass
+    dup.class.should.equal? klass
   end
 
   it "does not copy frozen state from the original" do
     @obj.freeze
     dup = @obj.dup
 
-    dup.frozen?.should == false
+    dup.should_not.frozen?
   end
 
   it "copies instance variables" do
@@ -44,7 +44,7 @@ describe "Kernel#dup" do
   it "does not copy singleton methods" do
     def @obj.special() :the_one end
     dup = @obj.dup
-    -> { dup.special }.should raise_error(NameError)
+    -> { dup.special }.should.raise(NameError)
   end
 
   it "does not copy modules included in the singleton class" do
@@ -53,7 +53,7 @@ describe "Kernel#dup" do
     end
 
     dup = @obj.dup
-    -> { dup.repr }.should raise_error(NameError)
+    -> { dup.repr }.should.raise(NameError)
   end
 
   it "does not copy constants defined in the singleton class" do
@@ -62,6 +62,6 @@ describe "Kernel#dup" do
     end
 
     dup = @obj.dup
-    -> { class << dup; CLONE; end }.should raise_error(NameError)
+    -> { class << dup; CLONE; end }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/kernel/eql_spec.rb b/spec/ruby/core/kernel/eql_spec.rb
index e62a601a79..b3289090e5 100644
--- a/spec/ruby/core/kernel/eql_spec.rb
+++ b/spec/ruby/core/kernel/eql_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../shared/kernel/equal'
 
 describe "Kernel#eql?" do
   it "is a public instance method" do
-    Kernel.should have_public_instance_method(:eql?)
+    Kernel.public_instance_methods(false).should.include?(:eql?)
   end
 
   it_behaves_like :object_equal, :eql?
diff --git a/spec/ruby/core/kernel/eval_spec.rb b/spec/ruby/core/kernel/eval_spec.rb
index 02f7ae87e9..f9ca47866e 100644
--- a/spec/ruby/core/kernel/eval_spec.rb
+++ b/spec/ruby/core/kernel/eval_spec.rb
@@ -5,7 +5,7 @@ EvalSpecs::A.new.c
 
 describe "Kernel#eval" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:eval)
+    Kernel.private_instance_methods(false).should.include?(:eval)
   end
 
   it "is a module function" do
@@ -76,12 +76,12 @@ describe "Kernel#eval" do
     x = 1
     bind = proc {}
 
-    -> { eval("x", bind) }.should raise_error(TypeError)
+    -> { eval("x", bind) }.should.raise(TypeError)
   end
 
   it "does not make Proc locals visible to evaluated code" do
     bind = proc { inner = 4 }
-    -> { eval("inner", bind.binding) }.should raise_error(NameError)
+    -> { eval("inner", bind.binding) }.should.raise(NameError)
   end
 
   # REWRITE ME: This obscures the real behavior of where locals are stored
@@ -119,7 +119,7 @@ describe "Kernel#eval" do
     outer_binding = binding
 
     eval("if false; a = 1; end", outer_binding)
-    eval("a", outer_binding).should be_nil
+    eval("a", outer_binding).should == nil
   end
 
   it "allows creating a new class in a binding" do
@@ -135,8 +135,8 @@ describe "Kernel#eval" do
   it "includes file and line information in syntax error" do
     expected = 'speccing.rb'
     -> {
-      eval('if true',TOPLEVEL_BINDING, expected)
-    }.should raise_error(SyntaxError) { |e|
+      eval('if true', TOPLEVEL_BINDING, expected)
+    }.should.raise(SyntaxError) { |e|
       e.message.should =~ /#{expected}:1:.+/
     }
   end
@@ -144,8 +144,8 @@ describe "Kernel#eval" do
   it "evaluates string with given filename and negative linenumber" do
     expected_file = 'speccing.rb'
     -> {
-      eval('if true',TOPLEVEL_BINDING, expected_file, -100)
-    }.should raise_error(SyntaxError) { |e|
+      eval('if true', TOPLEVEL_BINDING, expected_file, -100)
+    }.should.raise(SyntaxError) { |e|
       e.message.should =~ /#{expected_file}:-100:.+/
     }
   end
@@ -159,15 +159,88 @@ describe "Kernel#eval" do
     end
   end
 
-  it "uses the filename of the binding if none is provided" do
-    eval("__FILE__").should == "(eval)"
-    suppress_warning {eval("__FILE__", binding)}.should == __FILE__
+  context "parameter forwarding" do
+    it "allows anonymous rest parameter forwarding" do
+      object = Object.new
+      def object.foo(a, b, c)
+        [a, b, c]
+      end
+      def object.bar(*)
+        eval "foo(*)"
+      end
+
+      object.bar(1, 2, 3).should == [1, 2, 3]
+    end
+
+    it "allows anonymous keyword parameters forwarding" do
+      object = Object.new
+      def object.foo(a:, b:, c:)
+        [a, b, c]
+      end
+      def object.bar(**)
+        eval "foo(**)"
+      end
+
+      object.bar(a: 1, b: 2, c: 3).should == [1, 2, 3]
+    end
+
+    it "allows anonymous block parameter forwarding" do
+      object = Object.new
+      def object.foo(&block)
+        block.call
+      end
+      def object.bar(&)
+        eval "foo(&)"
+      end
+
+      object.bar { :foobar }.should == :foobar
+    end
+
+    it "allows ... forwarding" do
+      object = Object.new
+      def object.foo(a, b:, &block)
+        [a, b, block.call]
+      end
+      def object.bar(...)
+        eval "foo(...)"
+      end
+
+      object.bar(1, b: 2) { 3 }.should == [1, 2, 3]
+    end
+
+    it "allows parameter forwarding to super" do
+      m = Module.new do
+        def foo(a, b:, &block)
+          [a, b, block.call]
+        end
+      end
+
+      c = Class.new do
+        include m
+
+        def foo(a, b:, &block)
+          eval "super"
+        end
+      end
+
+      object = c.new
+      object.foo(1, b: 2) { 3 }.should == [1, 2, 3]
+    end
+  end
+
+  it "uses (eval at __FILE__:__LINE__) if none is provided" do
+    eval("__FILE__").should == "(eval at #{__FILE__}:#{__LINE__})"
+    eval("__FILE__", binding).should == "(eval at #{__FILE__}:#{__LINE__})"
     eval("__FILE__", binding, "success").should == "success"
-    suppress_warning {eval("eval '__FILE__', binding")}.should == "(eval)"
-    suppress_warning {eval("eval '__FILE__', binding", binding)}.should == __FILE__
-    suppress_warning {eval("eval '__FILE__', binding", binding, 'success')}.should == 'success'
+    eval("eval '__FILE__', binding").should == "(eval at (eval at #{__FILE__}:#{__LINE__}):1)"
+    eval("eval '__FILE__', binding", binding).should == "(eval at (eval at #{__FILE__}:#{__LINE__}):1)"
+    eval("eval '__FILE__', binding", binding, 'success').should == "(eval at success:1)"
+    eval("eval '__FILE__', binding, 'success'", binding).should == 'success'
   end
 
+  it 'uses (eval at __FILE__:__LINE__) for __FILE__ and 1 for __LINE__ with a binding argument' do
+    eval("[__FILE__, __LINE__]", binding).should == ["(eval at #{__FILE__}:#{__LINE__})", 1]
+  end
   # Found via Rubinius bug github:#149
   it "does not alter the value of __FILE__ in the binding" do
     first_time =  EvalSpecs.call_eval
@@ -190,20 +263,34 @@ describe "Kernel#eval" do
 
   # See http://jira.codehaus.org/browse/JRUBY-5163
   it "uses the receiver as self inside the eval" do
-    eval("self").should equal(self)
-    Kernel.eval("self").should equal(Kernel)
+    eval("self").should.equal?(self)
+    Kernel.eval("self").should.equal?(Kernel)
   end
 
   it "does not pass the block to the method being eval'ed" do
     -> {
       eval('KernelSpecs::EvalTest.call_yield') { "content" }
-    }.should raise_error(LocalJumpError)
+    }.should.raise(LocalJumpError)
   end
 
   it "returns from the scope calling #eval when evaluating 'return'" do
     -> { eval("return :eval") }.call.should == :eval
   end
 
+  it "returns from the method calling #eval when evaluating 'return'" do
+    def eval_return(n)
+      eval("return n*2")
+    end
+    -> { eval_return(3) }.call.should == 6
+  end
+
+  it "returns from the method calling #eval when evaluating 'return' in BEGIN" do
+    def eval_return(n)
+      eval("BEGIN {return n*3}")
+    end
+    -> { eval_return(4) }.call.should == 12
+  end
+
   it "unwinds through a Proc-style closure and returns from a lambda-style closure in the closure chain" do
     code = fixture __FILE__, "eval_return_with_lambda.rb"
     ruby_exe(code).chomp.should == "a,b,c,eval,f"
@@ -214,6 +301,50 @@ describe "Kernel#eval" do
     ruby_exe(code).chomp.should == "a,b,c,e,LocalJumpError,f"
   end
 
+  it "can be called with Method#call" do
+    method(:eval).call("2 * 3").should == 6
+  end
+
+  it "has the correct default definee when called through Method#call" do
+    class EvalSpecs
+      method(:eval).call("def eval_spec_method_call; end")
+      EvalSpecs.should.method_defined?(:eval_spec_method_call, false)
+    end
+  end
+
+  it "makes flip-flop operator work correctly" do
+    ScratchPad.record []
+
+    eval "10.times { |i| ScratchPad << i if (i == 4)...(i == 4) }"
+    ScratchPad.recorded.should == [4, 5, 6, 7, 8, 9]
+
+    ScratchPad.clear
+  end
+
+  it "returns nil if given an empty string" do
+    eval("").should == nil
+  end
+
+  context "with shebang" do
+    it "ignores shebang with ruby interpreter" do
+      pid = eval(<<~CODE.b)
+        #!/usr/bin/env ruby
+        Process.pid
+      CODE
+
+      pid.should == Process.pid
+    end
+
+    it "ignores shebang with non-ruby interpreter" do
+      pid = eval(<<~CODE.b)
+        #!/usr/bin/env puma
+        Process.pid
+      CODE
+
+      pid.should == Process.pid
+    end
+  end
+
   # See language/magic_comment_spec.rb for more magic comments specs
   describe "with a magic encoding comment" do
     it "uses the magic comment encoding for the encoding of literal strings" do
@@ -231,8 +362,10 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπ")
+      EvalSpecs.constants(false).should.include?(:"Vπ")
       EvalSpecs::Vπ.should == 3.14
+    ensure
+      EvalSpecs.send(:remove_const, :Vπ)
     end
 
     it "allows an emacs-style magic comment encoding" do
@@ -244,8 +377,10 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπemacs")
+      EvalSpecs.constants(false).should.include?(:"Vπemacs")
       EvalSpecs::Vπemacs.should == 3.14
+    ensure
+      EvalSpecs.send(:remove_const, :Vπemacs)
     end
 
     it "allows spaces before the magic encoding comment" do
@@ -257,8 +392,10 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπspaces")
+      EvalSpecs.constants(false).should.include?(:"Vπspaces")
       EvalSpecs::Vπspaces.should == 3.14
+    ensure
+      EvalSpecs.send(:remove_const, :Vπspaces)
     end
 
     it "allows a shebang line before the magic encoding comment" do
@@ -271,8 +408,10 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπshebang")
+      EvalSpecs.constants(false).should.include?(:"Vπshebang")
       EvalSpecs::Vπshebang.should == 3.14
+    ensure
+      EvalSpecs.send(:remove_const, :Vπshebang)
     end
 
     it "allows a shebang line and some spaces before the magic encoding comment" do
@@ -285,27 +424,30 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπshebang_spaces")
+      EvalSpecs.constants(false).should.include?(:"Vπshebang_spaces")
       EvalSpecs::Vπshebang_spaces.should == 3.14
+    ensure
+      EvalSpecs.send(:remove_const, :Vπshebang_spaces)
     end
 
     it "allows a magic encoding comment and a subsequent frozen_string_literal magic comment" do
-      # Make sure frozen_string_literal is not default true
-      eval("'foo'".b).frozen?.should be_false
+      frozen_string_default = "test".frozen?
 
       code = <<CODE.b
 # encoding: UTF-8
-# frozen_string_literal: true
+# frozen_string_literal: #{!frozen_string_default}
 class EvalSpecs
   Vπstring = "frozen"
 end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπstring")
+      EvalSpecs.constants(false).should.include?(:"Vπstring")
       EvalSpecs::Vπstring.should == "frozen"
       EvalSpecs::Vπstring.encoding.should == Encoding::UTF_8
-      EvalSpecs::Vπstring.frozen?.should be_true
+      EvalSpecs::Vπstring.frozen?.should == !frozen_string_default
+    ensure
+      EvalSpecs.send(:remove_const, :Vπstring)
     end
 
     it "allows a magic encoding comment and a frozen_string_literal magic comment on the same line in emacs style" do
@@ -317,15 +459,18 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should include(:"Vπsame_line")
+      EvalSpecs.constants(false).should.include?(:"Vπsame_line")
       EvalSpecs::Vπsame_line.should == "frozen"
       EvalSpecs::Vπsame_line.encoding.should == Encoding::UTF_8
-      EvalSpecs::Vπsame_line.frozen?.should be_true
+      EvalSpecs::Vπsame_line.frozen?.should == true
+    ensure
+      EvalSpecs.send(:remove_const, :Vπsame_line)
     end
 
     it "ignores the magic encoding comment if it is after a frozen_string_literal magic comment" do
+      frozen_string_default = "test".frozen?
       code = <<CODE.b
-# frozen_string_literal: true
+# frozen_string_literal: #{!frozen_string_default}
 # encoding: UTF-8
 class EvalSpecs
   Vπfrozen_first = "frozen"
@@ -333,13 +478,75 @@ end
 CODE
       code.encoding.should == Encoding::BINARY
       eval(code)
-      EvalSpecs.constants(false).should_not include(:"Vπfrozen_first")
+      EvalSpecs.constants(false).should_not.include?(:"Vπfrozen_first")
       binary_constant = "Vπfrozen_first".b.to_sym
-      EvalSpecs.constants(false).should include(binary_constant)
+      EvalSpecs.constants(false).should.include?(binary_constant)
       value = EvalSpecs.const_get(binary_constant)
       value.should == "frozen"
       value.encoding.should == Encoding::BINARY
-      value.frozen?.should be_true
+      value.frozen?.should == !frozen_string_default
+    ensure
+      EvalSpecs.send(:remove_const, binary_constant)
+    end
+
+    it "ignores the frozen_string_literal magic comment if it appears after a token and warns if $VERBOSE is true" do
+      frozen_string_default = "test".frozen?
+      code = <<CODE
+some_token_before_magic_comment = :anything
+# frozen_string_literal: #{!frozen_string_default}
+class EvalSpecs
+  Vπstring_not_frozen = "not frozen"
+end
+CODE
+      -> { eval(code) }.should complain(/warning: [`']frozen_string_literal' is ignored after any tokens/, verbose: true)
+      EvalSpecs::Vπstring_not_frozen.frozen?.should == frozen_string_default
+      EvalSpecs.send :remove_const, :Vπstring_not_frozen
+
+      -> { eval(code) }.should_not complain(verbose: false)
+      EvalSpecs::Vπstring_not_frozen.frozen?.should == frozen_string_default
+      EvalSpecs.send :remove_const, :Vπstring_not_frozen
+    end
+  end
+
+  describe 'with refinements' do
+    it "activates refinements from the eval scope" do
+      refinery = Module.new do
+        refine EvalSpecs::A do
+          def foo
+            "bar"
+          end
+        end
+      end
+
+      result = nil
+
+      Module.new do
+        using refinery
+
+        result = eval "EvalSpecs::A.new.foo"
+      end
+
+      result.should == "bar"
+    end
+
+    it "activates refinements from the binding" do
+      refinery = Module.new do
+        refine EvalSpecs::A do
+          def foo
+            "bar"
+          end
+        end
+      end
+
+      b = nil
+      m = Module.new do
+        using refinery
+        b = binding
+      end
+
+      result = eval "EvalSpecs::A.new.foo", b
+
+      result.should == "bar"
     end
   end
 end
diff --git a/spec/ruby/core/kernel/exec_spec.rb b/spec/ruby/core/kernel/exec_spec.rb
index 1b4a7ae6f4..fd8485791a 100644
--- a/spec/ruby/core/kernel/exec_spec.rb
+++ b/spec/ruby/core/kernel/exec_spec.rb
@@ -3,16 +3,16 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#exec" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:exec)
+    Kernel.private_instance_methods(false).should.include?(:exec)
   end
 
   it "runs the specified command, replacing current process" do
-    ruby_exe('exec "echo hello"; puts "fail"', escape: true).should == "hello\n"
+    ruby_exe('exec "echo hello"; puts "fail"').should == "hello\n"
   end
 end
 
 describe "Kernel.exec" do
   it "runs the specified command, replacing current process" do
-    ruby_exe('Kernel.exec "echo hello"; puts "fail"', escape: true).should == "hello\n"
+    ruby_exe('Kernel.exec "echo hello"; puts "fail"').should == "hello\n"
   end
 end
diff --git a/spec/ruby/core/kernel/exit_spec.rb b/spec/ruby/core/kernel/exit_spec.rb
index f168cb375e..864ff84449 100644
--- a/spec/ruby/core/kernel/exit_spec.rb
+++ b/spec/ruby/core/kernel/exit_spec.rb
@@ -4,24 +4,24 @@ require_relative '../../shared/process/exit'
 
 describe "Kernel#exit" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:exit)
+    Kernel.private_instance_methods(false).should.include?(:exit)
   end
 
   it_behaves_like :process_exit, :exit, KernelSpecs::Method.new
 end
 
+describe "Kernel.exit" do
+  it_behaves_like :process_exit, :exit, Kernel
+end
+
 describe "Kernel#exit!" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:exit!)
+    Kernel.private_instance_methods(false).should.include?(:exit!)
   end
 
   it_behaves_like :process_exit!, :exit!, "self"
 end
 
-describe "Kernel.exit" do
-  it_behaves_like :process_exit, :exit, Kernel
-end
-
 describe "Kernel.exit!" do
-  it_behaves_like :process_exit!, :exit!, Kernel
+  it_behaves_like :process_exit!, :exit!, "Kernel"
 end
diff --git a/spec/ruby/core/kernel/extend_spec.rb b/spec/ruby/core/kernel/extend_spec.rb
index 9f98b3681f..a344c7b5ca 100644
--- a/spec/ruby/core/kernel/extend_spec.rb
+++ b/spec/ruby/core/kernel/extend_spec.rb
@@ -53,13 +53,13 @@ describe "Kernel#extend" do
   end
 
   it "raises an ArgumentError when no arguments given" do
-    -> { Object.new.extend }.should raise_error(ArgumentError)
+    -> { Object.new.extend }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError when the argument is not a Module" do
     o = mock('o')
     klass = Class.new
-    -> { o.extend(klass) }.should raise_error(TypeError)
+    -> { o.extend(klass) }.should.raise(TypeError)
   end
 
   describe "on frozen instance" do
@@ -69,11 +69,23 @@ describe "Kernel#extend" do
     end
 
     it "raises an ArgumentError when no arguments given" do
-      -> { @frozen.extend }.should raise_error(ArgumentError)
+      -> { @frozen.extend }.should.raise(ArgumentError)
     end
 
-    it "raises a #{frozen_error_class}" do
-      -> { @frozen.extend @module }.should raise_error(frozen_error_class)
+    it "raises a FrozenError" do
+      -> { @frozen.extend @module }.should.raise(FrozenError)
     end
   end
+
+  it "updated class methods of a module when it extends self and includes another module" do
+    a = Module.new do
+      extend self
+    end
+    b = Module.new do
+      def foo; :foo; end
+    end
+
+    a.include b
+    a.foo.should == :foo
+  end
 end
diff --git a/spec/ruby/core/kernel/fail_spec.rb b/spec/ruby/core/kernel/fail_spec.rb
index fab622037e..ac379b67d5 100644
--- a/spec/ruby/core/kernel/fail_spec.rb
+++ b/spec/ruby/core/kernel/fail_spec.rb
@@ -3,11 +3,11 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#fail" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:fail)
+    Kernel.private_instance_methods(false).should.include?(:fail)
   end
 
   it "raises a RuntimeError" do
-    -> { fail }.should raise_error(RuntimeError)
+    -> { fail }.should.raise(RuntimeError)
   end
 
   it "accepts an Object with an exception method returning an Exception" do
@@ -15,12 +15,12 @@ describe "Kernel#fail" do
     def obj.exception(msg)
       StandardError.new msg
     end
-    -> { fail obj, "..." }.should raise_error(StandardError, "...")
+    -> { fail obj, "..." }.should.raise(StandardError, "...")
   end
 
   it "instantiates the specified exception class" do
     error_class = Class.new(RuntimeError)
-    -> { fail error_class }.should raise_error(error_class)
+    -> { fail error_class }.should.raise(error_class)
   end
 
   it "uses the specified message" do
@@ -33,7 +33,7 @@ describe "Kernel#fail" do
       else
         raise Exception
       end
-    }.should raise_error(RuntimeError)
+    }.should.raise(RuntimeError)
   end
 end
 
diff --git a/spec/ruby/core/kernel/fixtures/Complex.rb b/spec/ruby/core/kernel/fixtures/Complex.rb
new file mode 100644
index 0000000000..bf14d55ad5
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/Complex.rb
@@ -0,0 +1,5 @@
+module KernelSpecs
+  def self.Complex_method(string)
+    Complex(string)
+  end
+end
diff --git a/spec/ruby/core/kernel/fixtures/__dir__.rb b/spec/ruby/core/kernel/fixtures/__dir__.rb
new file mode 100644
index 0000000000..bf9a15e3c8
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/__dir__.rb
@@ -0,0 +1,2 @@
+puts __FILE__
+puts __dir__
diff --git a/spec/ruby/core/kernel/fixtures/autoload_relative_b.rb b/spec/ruby/core/kernel/fixtures/autoload_relative_b.rb
new file mode 100644
index 0000000000..6de6f5091d
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/autoload_relative_b.rb
@@ -0,0 +1,7 @@
+module KernelSpecs
+  module KSAutoloadRelativeB
+    def self.loaded
+      :ksautoload_b
+    end
+  end
+end
diff --git a/spec/ruby/core/kernel/fixtures/autoload_relative_d.rb b/spec/ruby/core/kernel/fixtures/autoload_relative_d.rb
new file mode 100644
index 0000000000..5b6b5e1fa2
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/autoload_relative_d.rb
@@ -0,0 +1,5 @@
+module KSAutoloadRelativeD
+  def self.loaded
+    :ksautoload_d
+  end
+end
diff --git a/spec/ruby/core/kernel/fixtures/classes.rb b/spec/ruby/core/kernel/fixtures/classes.rb
index 2909a621a9..ad82f3cef5 100644
--- a/spec/ruby/core/kernel/fixtures/classes.rb
+++ b/spec/ruby/core/kernel/fixtures/classes.rb
@@ -49,7 +49,7 @@ module KernelSpecs
 
   def self.chomp(str, method, sep="\n")
     code = "$_ = #{str.inspect}; $/ = #{sep.inspect}; #{method}; print $_"
-    IO.popen([*ruby_exe, "-n", "-e", code], "r+") do |io|
+    IO.popen([*ruby_exe, "-W0", "-n", "-e", code], "r+") do |io|
       io.puts
       io.close_write
       io.read
@@ -180,6 +180,25 @@ module KernelSpecs
     alias aliased_pub_method pub_method
   end
 
+  class BasicA < BasicObject
+    define_method(:respond_to?, ::Kernel.instance_method(:respond_to?))
+
+    def pub_method; :public_method; end
+
+    def undefed_method; :undefed_method; end
+    undef_method :undefed_method
+
+    protected
+    def protected_method; :protected_method; end
+
+    private
+    def private_method; :private_method; end
+  end
+
+  class MissingA < A
+    undef :respond_to_missing?
+  end
+
   class VisibilityChange
     class << self
       private :new
@@ -219,10 +238,28 @@ module KernelSpecs
       block_given?
     end
 
+    def self.accept_block_inside_block()
+      yield_self {
+        block_given?
+      }
+    end
+
+    def self.accept_block_as_argument_inside_block(&block)
+      yield_self {
+        block_given?
+      }
+    end
+
     class << self
       define_method(:defined_block) do
         block_given?
       end
+
+      define_method(:defined_block_inside_block) do
+        yield_self {
+          block_given?
+        }
+      end
     end
   end
 
@@ -235,10 +272,28 @@ module KernelSpecs
       self.send(:block_given?)
     end
 
+    def self.accept_block_inside_block
+      yield_self {
+        self.send(:block_given?)
+      }
+    end
+
+    def self.accept_block_as_argument_inside_block(&block)
+      yield_self {
+        self.send(:block_given?)
+      }
+    end
+
     class << self
       define_method(:defined_block) do
         self.send(:block_given?)
       end
+
+      define_method(:defined_block_inside_block) do
+        yield_self {
+          self.send(:block_given?)
+        }
+      end
     end
   end
 
@@ -251,10 +306,28 @@ module KernelSpecs
       Kernel.block_given?
     end
 
+    def self.accept_block_inside_block
+      yield_self {
+        Kernel.block_given?
+      }
+    end
+
+    def self.accept_block_as_argument_inside_block(&block)
+      yield_self {
+        Kernel.block_given?
+      }
+    end
+
     class << self
       define_method(:defined_block) do
         Kernel.block_given?
       end
+
+      define_method(:defined_block_inside_block) do
+        yield_self {
+          Kernel.block_given?
+        }
+      end
     end
   end
 
@@ -281,14 +354,25 @@ module KernelSpecs
       @two = two
     end
 
-    def initialize_copy(other)
+    def initialize_copy(other, **kw)
       ScratchPad.record object_id
     end
+
+    # define to support calling #clone with optional :freeze keyword argument
+    def initialize_clone(other, **kw)
+      super(other) # to call #initialize_copy
+    end
   end
 
   class Clone
     def initialize_clone(other)
-      ScratchPad.record other.object_id
+      ScratchPad.record other
+    end
+  end
+
+  class CloneFreeze
+    def initialize_clone(other, **kwargs)
+      ScratchPad.record([other, kwargs])
     end
   end
 
@@ -337,21 +421,44 @@ module KernelSpecs
     end
   end
 
+  module LambdaSpecs
+    module ZSuper
+      def lambda
+        super
+      end
+    end
+
+    class ForwardBlockWithZSuper
+      prepend(ZSuper)
+    end
+
+    module Ampersand
+      def lambda(&block)
+        suppress_warning {super(&block)}
+      end
+    end
+
+    class SuperAmpersand
+      prepend(Ampersand)
+    end
+  end
+
   class RespondViaMissing
     def respond_to_missing?(method, priv=false)
       case method
-        when :handled_publicly
-          true
-        when :handled_privately
-          priv
-        when :not_handled
-          false
-        else
-          raise "Typo in method name"
+      when :handled_publicly
+        true
+      when :handled_privately
+        priv
+      when :not_handled
+        false
+      else
+        raise "Typo in method name: #{method.inspect}"
       end
     end
 
     def method_missing(method, *args)
+      raise "the method name should be a Symbol" unless Symbol === method
       "Done #{method}(#{args})"
     end
   end
diff --git a/spec/ruby/core/kernel/fixtures/warn_core_method.rb b/spec/ruby/core/kernel/fixtures/warn_core_method.rb
new file mode 100644
index 0000000000..fd82562404
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/warn_core_method.rb
@@ -0,0 +1,14 @@
+raise 'should be run without RubyGems' if defined?(Gem)
+
+public def deprecated(n=1)
+  # puts nil, caller(0), nil
+  warn "use X instead", uplevel: n
+end
+
+1.times do # to test with a non-empty stack above the reported locations
+  deprecated
+  tap(&:deprecated)
+  tap { deprecated(2) }
+  # eval sources with a <internal: file are also ignored
+  eval "tap(&:deprecated)", nil, "<internal:should-be-skipped-by-warn-uplevel>"
+end
diff --git a/spec/ruby/core/kernel/fixtures/warn_require.rb b/spec/ruby/core/kernel/fixtures/warn_require.rb
new file mode 100644
index 0000000000..c4b0733233
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/warn_require.rb
@@ -0,0 +1 @@
+warn 'warn-require-warning', uplevel: 1
diff --git a/spec/ruby/core/kernel/fixtures/warn_require_caller.rb b/spec/ruby/core/kernel/fixtures/warn_require_caller.rb
new file mode 100644
index 0000000000..35a0f969f9
--- /dev/null
+++ b/spec/ruby/core/kernel/fixtures/warn_require_caller.rb
@@ -0,0 +1,2 @@
+# Use a different line than just 1
+require "#{__dir__}/warn_require"
diff --git a/spec/ruby/core/kernel/fork_spec.rb b/spec/ruby/core/kernel/fork_spec.rb
index b37f9980e0..4a2c848202 100644
--- a/spec/ruby/core/kernel/fork_spec.rb
+++ b/spec/ruby/core/kernel/fork_spec.rb
@@ -4,7 +4,7 @@ require_relative '../../shared/process/fork'
 
 describe "Kernel#fork" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:fork)
+    Kernel.private_instance_methods(false).should.include?(:fork)
   end
 
   it_behaves_like :process_fork, :fork, KernelSpecs::Method.new
diff --git a/spec/ruby/core/kernel/format_spec.rb b/spec/ruby/core/kernel/format_spec.rb
index 72fd40b952..35c752b1ab 100644
--- a/spec/ruby/core/kernel/format_spec.rb
+++ b/spec/ruby/core/kernel/format_spec.rb
@@ -1,9 +1,10 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
+# NOTE: most specs are in sprintf_spec.rb, this is just an alias
 describe "Kernel#format" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:format)
+    Kernel.private_instance_methods(false).should.include?(:format)
   end
 end
 
@@ -11,4 +12,36 @@ describe "Kernel.format" do
   it "is accessible as a module function" do
     Kernel.format("%s", "hello").should == "hello"
   end
+
+  describe "when $VERBOSE is true" do
+    it "warns if too many arguments are passed" do
+      code = <<~RUBY
+        $VERBOSE = true
+        format("test", 1)
+      RUBY
+
+      ruby_exe(code, args: "2>&1").should.include?("warning: too many arguments for format string")
+    end
+
+    it "does not warns if too many keyword arguments are passed" do
+      code = <<~RUBY
+        $VERBOSE = true
+        format("test %{test}", test: 1, unused: 2)
+      RUBY
+
+      ruby_exe(code, args: "2>&1").should_not.include?("warning")
+    end
+
+    ruby_bug "#20593", ""..."3.4" do
+      it "doesn't warns if keyword arguments are passed and none are used" do
+        code = <<~RUBY
+          $VERBOSE = true
+          format("test", test: 1)
+          format("test", {})
+        RUBY
+
+        ruby_exe(code, args: "2>&1").should_not.include?("warning")
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/freeze_spec.rb b/spec/ruby/core/kernel/freeze_spec.rb
index 214b619f9f..079617dce4 100644
--- a/spec/ruby/core/kernel/freeze_spec.rb
+++ b/spec/ruby/core/kernel/freeze_spec.rb
@@ -4,46 +4,46 @@ require_relative 'fixtures/classes'
 describe "Kernel#freeze" do
   it "prevents self from being further modified" do
     o = mock('o')
-    o.frozen?.should be_false
+    o.frozen?.should == false
     o.freeze
-    o.frozen?.should be_true
+    o.frozen?.should == true
   end
 
   it "returns self" do
     o = Object.new
-    o.freeze.should equal(o)
+    o.freeze.should.equal?(o)
   end
 
   describe "on integers" do
     it "has no effect since they are already frozen" do
-      1.frozen?.should be_true
+      1.frozen?.should == true
       1.freeze
 
       bignum = bignum_value
-      bignum.frozen?.should be_true
+      bignum.frozen?.should == true
       bignum.freeze
     end
   end
 
   describe "on a Float" do
     it "has no effect since it is already frozen" do
-      1.2.frozen?.should be_true
+      1.2.frozen?.should == true
       1.2.freeze
     end
   end
 
   describe "on a Symbol" do
     it "has no effect since it is already frozen" do
-      :sym.frozen?.should be_true
+      :sym.frozen?.should == true
       :sym.freeze
     end
   end
 
   describe "on true, false and nil" do
     it "has no effect since they are already frozen" do
-      nil.frozen?.should be_true
-      true.frozen?.should be_true
-      false.frozen?.should be_true
+      nil.frozen?.should == true
+      true.frozen?.should == true
+      false.frozen?.should == true
 
       nil.freeze
       true.freeze
@@ -51,21 +51,19 @@ describe "Kernel#freeze" do
     end
   end
 
-  ruby_version_is "2.5" do
-    describe "on a Complex" do
-      it "has no effect since it is already frozen" do
-        c = Complex(1.3, 3.1)
-        c.frozen?.should be_true
-        c.freeze
-      end
+  describe "on a Complex" do
+    it "has no effect since it is already frozen" do
+      c = Complex(1.3, 3.1)
+      c.frozen?.should == true
+      c.freeze
     end
+  end
 
-    describe "on a Rational" do
-      it "has no effect since it is already frozen" do
-        r = Rational(1, 3)
-        r.frozen?.should be_true
-        r.freeze
-      end
+  describe "on a Rational" do
+    it "has no effect since it is already frozen" do
+      r = Rational(1, 3)
+      r.frozen?.should == true
+      r.freeze
     end
   end
 
@@ -74,12 +72,20 @@ describe "Kernel#freeze" do
       def mutate; @foo = 1; end
     end.new
     o.freeze
-    -> {o.mutate}.should raise_error(RuntimeError)
+    -> {o.mutate}.should.raise(RuntimeError)
   end
 
   it "causes instance_variable_set to raise RuntimeError" do
     o = Object.new
     o.freeze
-    -> {o.instance_variable_set(:@foo, 1)}.should raise_error(RuntimeError)
+    -> {o.instance_variable_set(:@foo, 1)}.should.raise(RuntimeError)
+  end
+
+  it "freezes an object's singleton class" do
+    o = Object.new
+    c = o.singleton_class
+    c.frozen?.should == false
+    o.freeze
+    c.frozen?.should == true
   end
 end
diff --git a/spec/ruby/core/kernel/frozen_spec.rb b/spec/ruby/core/kernel/frozen_spec.rb
index 5887ed75ba..8b8fad3de7 100644
--- a/spec/ruby/core/kernel/frozen_spec.rb
+++ b/spec/ruby/core/kernel/frozen_spec.rb
@@ -6,15 +6,15 @@ describe "Kernel#frozen?" do
     o = mock('o')
     p = mock('p')
     p.freeze
-    o.frozen?.should == false
-    p.frozen?.should == true
+    o.should_not.frozen?
+    p.should.frozen?
   end
 
   describe "on true, false and nil" do
     it "returns true" do
-      true.frozen?.should be_true
-      false.frozen?.should be_true
-      nil.frozen?.should be_true
+      true.frozen?.should == true
+      false.frozen?.should == true
+      nil.frozen?.should == true
     end
   end
 
@@ -25,8 +25,8 @@ describe "Kernel#frozen?" do
     end
 
     it "returns true" do
-      @fixnum.frozen?.should be_true
-      @bignum.frozen?.should be_true
+      @fixnum.frozen?.should == true
+      @bignum.frozen?.should == true
     end
   end
 
@@ -36,7 +36,7 @@ describe "Kernel#frozen?" do
     end
 
     it "returns true" do
-      @float.frozen?.should be_true
+      @float.frozen?.should == true
     end
   end
 
@@ -46,33 +46,31 @@ describe "Kernel#frozen?" do
     end
 
     it "returns true" do
-      @symbol.frozen?.should be_true
+      @symbol.frozen?.should == true
     end
   end
 
-  ruby_version_is "2.5" do
-    describe "on a Complex" do
-      it "returns true" do
-        c = Complex(1.3, 3.1)
-        c.frozen?.should be_true
-      end
+  describe "on a Complex" do
+    it "returns true" do
+      c = Complex(1.3, 3.1)
+      c.frozen?.should == true
+    end
 
-      it "literal returns true" do
-        c = eval "1.3i"
-        c.frozen?.should be_true
-      end
+    it "literal returns true" do
+      c = eval "1.3i"
+      c.frozen?.should == true
     end
+  end
 
-    describe "on a Rational" do
-      it "returns true" do
-        r = Rational(1, 3)
-        r.frozen?.should be_true
-      end
+  describe "on a Rational" do
+    it "returns true" do
+      r = Rational(1, 3)
+      r.frozen?.should == true
+    end
 
-      it "literal returns true" do
-        r = eval "1/3r"
-        r.frozen?.should be_true
-      end
+    it "literal returns true" do
+      r = eval "1/3r"
+      r.frozen?.should == true
     end
   end
 end
diff --git a/spec/ruby/core/kernel/gets_spec.rb b/spec/ruby/core/kernel/gets_spec.rb
index 104613dbfa..1b2b36fbb9 100644
--- a/spec/ruby/core/kernel/gets_spec.rb
+++ b/spec/ruby/core/kernel/gets_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#gets" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:gets)
+    Kernel.private_instance_methods(false).should.include?(:gets)
   end
 
   it "calls ARGF.gets" do
diff --git a/spec/ruby/core/kernel/global_variables_spec.rb b/spec/ruby/core/kernel/global_variables_spec.rb
index 8bce8e25b7..d41bdff49a 100644
--- a/spec/ruby/core/kernel/global_variables_spec.rb
+++ b/spec/ruby/core/kernel/global_variables_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel.global_variables" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:global_variables)
+    Kernel.private_instance_methods(false).should.include?(:global_variables)
   end
 
   before :all do
@@ -11,13 +11,13 @@ describe "Kernel.global_variables" do
   end
 
   it "finds subset starting with std" do
-    global_variables.grep(/std/).should include(:$stderr, :$stdin, :$stdout)
+    global_variables.grep(/std/).to_set.should >= Set[:$stderr, :$stdin, :$stdout]
     a = global_variables.size
     gvar_name = "$foolish_global_var#{@i += 1}"
     global_variables.include?(gvar_name.to_sym).should == false
     eval("#{gvar_name} = 1")
     global_variables.size.should == a+1
-    global_variables.should include(gvar_name.to_sym)
+    global_variables.should.include?(gvar_name.to_sym)
   end
 end
 
diff --git a/spec/ruby/core/kernel/gsub_spec.rb b/spec/ruby/core/kernel/gsub_spec.rb
index a0cb9f2a70..e05349e2b5 100644
--- a/spec/ruby/core/kernel/gsub_spec.rb
+++ b/spec/ruby/core/kernel/gsub_spec.rb
@@ -6,20 +6,20 @@ require_relative 'fixtures/classes'
 ruby_version_is ""..."1.9" do
   describe "Kernel#gsub" do
     it "is a private method" do
-      Kernel.should have_private_instance_method(:gsub)
+      Kernel.private_instance_methods(false).should.include?(:gsub)
     end
 
     it "raises a TypeError if $_ is not a String" do
       -> {
         $_ = 123
         gsub(/./, "!")
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
 
     it "when matches sets $_ to a new string, leaving the former value unaltered" do
       orig_value = $_ = "hello"
       gsub("ello", "ola")
-      $_.should_not equal(orig_value)
+      $_.should_not.equal?(orig_value)
       $_.should == "hola"
       orig_value.should == "hello"
     end
@@ -86,7 +86,7 @@ ruby_version_is ""..."1.9" do
 
   describe "Kernel#gsub!" do
     it "is a private method" do
-      Kernel.should have_private_instance_method(:gsub!)
+      Kernel.private_instance_methods(false).should.include?(:gsub!)
     end
   end
 
diff --git a/spec/ruby/core/kernel/initialize_clone_spec.rb b/spec/ruby/core/kernel/initialize_clone_spec.rb
new file mode 100644
index 0000000000..0033eadffb
--- /dev/null
+++ b/spec/ruby/core/kernel/initialize_clone_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Kernel#initialize_clone" do
+  it "is a private instance method" do
+    Kernel.private_instance_methods(false).should.include?(:initialize_clone)
+  end
+
+  it "returns the receiver" do
+    a = Object.new
+    b = Object.new
+    a.send(:initialize_clone, b).should == a
+  end
+
+  it "calls #initialize_copy" do
+    a = Object.new
+    b = Object.new
+    a.should_receive(:initialize_copy).with(b)
+    a.send(:initialize_clone, b)
+  end
+
+  it "accepts a :freeze keyword argument for obj.clone(freeze: value)" do
+    a = Object.new
+    b = Object.new
+    a.send(:initialize_clone, b, freeze: true).should == a
+  end
+end
diff --git a/spec/ruby/core/kernel/initialize_copy_spec.rb b/spec/ruby/core/kernel/initialize_copy_spec.rb
new file mode 100644
index 0000000000..ebac0c14de
--- /dev/null
+++ b/spec/ruby/core/kernel/initialize_copy_spec.rb
@@ -0,0 +1,36 @@
+require_relative '../../spec_helper'
+
+describe "Kernel#initialize_copy" do
+  it "returns self" do
+    obj = Object.new
+    obj.send(:initialize_copy, obj).should.equal?(obj)
+  end
+
+  it "does nothing if the argument is the same as the receiver" do
+    obj = Object.new
+    obj.send(:initialize_copy, obj).should.equal?(obj)
+
+    obj = Object.new.freeze
+    obj.send(:initialize_copy, obj).should.equal?(obj)
+
+    1.send(:initialize_copy, 1).should.equal?(1)
+  end
+
+  it "raises FrozenError if the receiver is frozen" do
+    -> { Object.new.freeze.send(:initialize_copy, Object.new) }.should.raise(FrozenError)
+    -> { 1.send(:initialize_copy, Object.new) }.should.raise(FrozenError)
+  end
+
+  it "raises TypeError if the objects are of different class" do
+    klass = Class.new
+    sub = Class.new(klass)
+    a = klass.new
+    b = sub.new
+    message = 'initialize_copy should take same class object'
+    -> { a.send(:initialize_copy, b) }.should.raise(TypeError, message)
+    -> { b.send(:initialize_copy, a) }.should.raise(TypeError, message)
+
+    -> { a.send(:initialize_copy, 1) }.should.raise(TypeError, message)
+    -> { a.send(:initialize_copy, 1.0) }.should.raise(TypeError, message)
+  end
+end
diff --git a/spec/ruby/core/kernel/initialize_dup_spec.rb b/spec/ruby/core/kernel/initialize_dup_spec.rb
new file mode 100644
index 0000000000..f144647eb8
--- /dev/null
+++ b/spec/ruby/core/kernel/initialize_dup_spec.rb
@@ -0,0 +1,20 @@
+require_relative '../../spec_helper'
+
+describe "Kernel#initialize_dup" do
+  it "is a private instance method" do
+    Kernel.private_instance_methods(false).should.include?(:initialize_dup)
+  end
+
+  it "returns the receiver" do
+    a = Object.new
+    b = Object.new
+    a.send(:initialize_dup, b).should == a
+  end
+
+  it "calls #initialize_copy" do
+    a = Object.new
+    b = Object.new
+    a.should_receive(:initialize_copy).with(b)
+    a.send(:initialize_dup, b)
+  end
+end
diff --git a/spec/ruby/core/kernel/inspect_spec.rb b/spec/ruby/core/kernel/inspect_spec.rb
index b5ba1a3903..8fc3ab51cd 100644
--- a/spec/ruby/core/kernel/inspect_spec.rb
+++ b/spec/ruby/core/kernel/inspect_spec.rb
@@ -3,15 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#inspect" do
   it "returns a String" do
-    Object.new.inspect.should be_an_instance_of(String)
-  end
-
-  it "returns a tainted string if self is tainted" do
-    Object.new.taint.inspect.tainted?.should be_true
-  end
-
-  it "returns an untrusted string if self is untrusted" do
-    Object.new.untrust.inspect.untrusted?.should be_true
+    Object.new.inspect.should.instance_of?(String)
   end
 
   it "does not call #to_s if it is defined" do
@@ -28,4 +20,84 @@ describe "Kernel#inspect" do
     obj = Object.new
     obj.inspect.should =~ /^#<Object:0x[0-9a-f]+>$/
   end
+
+  it "returns a String for an object without #class method" do
+    obj = Object.new
+    class << obj
+      undef_method :class
+    end
+    obj.inspect.should.is_a?(String)
+  end
+
+  ruby_version_is "4.0" do
+    it "calls #instance_variables_to_inspect private method to know which variables to display" do
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = %i[@host @user @does_not_exist]
+      end
+
+      inspected = obj.inspect.sub(/^#<Object:0x[0-9a-f]+/, '#<Object:0x00')
+      inspected.should == '#<Object:0x00 @host="localhost", @user="root">'
+
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = []
+      end
+
+      inspected = obj.inspect.sub(/^#<Object:0x[0-9a-f]+/, '#<Object:0x00')
+      inspected.should == "#<Object:0x00>"
+    end
+
+    it "displays all instance variables if #instance_variables_to_inspect returns nil" do
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = nil
+      end
+
+      inspected = obj.inspect.sub(/^#<Object:0x[0-9a-f]+/, '#<Object:0x00')
+      inspected.should ==  %{#<Object:0x00 @host="localhost", @user="root", @password="hunter2">}
+    end
+
+    it "displays all instance variables if #instance_variables_to_inspect is not defined" do
+      obj = BasicObject.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      method_inspect = Kernel.instance_method(:inspect)
+
+      inspected = method_inspect.bind(obj).call.sub(/^#<BasicObject:0x[0-9a-f]+/, '#<BasicObject:0x00')
+      inspected.should ==  %{#<BasicObject:0x00 @host="localhost", @user="root", @password="hunter2">}
+    end
+
+    it "raises an error if #instance_variables_to_inspect returns an invalid value" do
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = {}
+      end
+
+      ->{ obj.inspect }.should.raise(TypeError, "Expected #instance_variables_to_inspect to return an Array or nil, but it returned Hash")
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/instance_of_spec.rb b/spec/ruby/core/kernel/instance_of_spec.rb
index 40e856b0d9..8d19974aa3 100644
--- a/spec/ruby/core/kernel/instance_of_spec.rb
+++ b/spec/ruby/core/kernel/instance_of_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe Kernel, "#instance_of?" do
+describe "Kernel#instance_of?" do
   before :each do
     @o = KernelSpecs::InstanceClass.new
   end
@@ -33,8 +33,8 @@ describe Kernel, "#instance_of?" do
   end
 
   it "raises a TypeError if given an object that is not a Class nor a Module" do
-    -> { @o.instance_of?(Object.new) }.should raise_error(TypeError)
-    -> { @o.instance_of?('KernelSpecs::InstanceClass') }.should raise_error(TypeError)
-    -> { @o.instance_of?(1) }.should raise_error(TypeError)
+    -> { @o.instance_of?(Object.new) }.should.raise(TypeError)
+    -> { @o.instance_of?('KernelSpecs::InstanceClass') }.should.raise(TypeError)
+    -> { @o.instance_of?(1) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/kernel/instance_variable_defined_spec.rb b/spec/ruby/core/kernel/instance_variable_defined_spec.rb
index 2ebb582b43..512f811393 100644
--- a/spec/ruby/core/kernel/instance_variable_defined_spec.rb
+++ b/spec/ruby/core/kernel/instance_variable_defined_spec.rb
@@ -8,21 +8,21 @@ describe "Kernel#instance_variable_defined?" do
 
   describe "when passed a String" do
     it "returns false if the instance variable is not defined" do
-      @instance.instance_variable_defined?("@goodbye").should be_false
+      @instance.instance_variable_defined?("@goodbye").should == false
     end
 
     it "returns true if the instance variable is defined" do
-      @instance.instance_variable_defined?("@greeting").should be_true
+      @instance.instance_variable_defined?("@greeting").should == true
     end
   end
 
   describe "when passed a Symbol" do
     it "returns false if the instance variable is not defined" do
-      @instance.instance_variable_defined?(:@goodbye).should be_false
+      @instance.instance_variable_defined?(:@goodbye).should == false
     end
 
     it "returns true if the instance variable is defined" do
-      @instance.instance_variable_defined?(:@greeting).should be_true
+      @instance.instance_variable_defined?(:@greeting).should == true
     end
   end
 
@@ -30,12 +30,12 @@ describe "Kernel#instance_variable_defined?" do
     -> do
       obj = mock("kernel instance_variable_defined?")
       @instance.instance_variable_defined? obj
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "returns false if the instance variable is not defined for different types" do
     [nil, false, true, 1, 2.0, :test, "test"].each do |obj|
-      obj.instance_variable_defined?("@goodbye").should be_false
+      obj.instance_variable_defined?("@goodbye").should == false
     end
   end
 end
diff --git a/spec/ruby/core/kernel/instance_variable_get_spec.rb b/spec/ruby/core/kernel/instance_variable_get_spec.rb
index 84d3188f07..8404c94192 100644
--- a/spec/ruby/core/kernel/instance_variable_get_spec.rb
+++ b/spec/ruby/core/kernel/instance_variable_get_spec.rb
@@ -20,29 +20,29 @@ describe "Kernel#instance_variable_get" do
   end
 
   it "returns nil when the referred instance variable does not exist" do
-    @obj.instance_variable_get(:@does_not_exist).should be_nil
+    @obj.instance_variable_get(:@does_not_exist).should == nil
   end
 
   it "raises a TypeError when the passed argument does not respond to #to_str" do
-    -> { @obj.instance_variable_get(Object.new) }.should raise_error(TypeError)
+    -> { @obj.instance_variable_get(Object.new) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when the passed argument can't be converted to a String" do
     obj = mock("to_str")
     obj.stub!(:to_str).and_return(123)
-    -> { @obj.instance_variable_get(obj) }.should raise_error(TypeError)
+    -> { @obj.instance_variable_get(obj) }.should.raise(TypeError)
   end
 
   it "raises a NameError when the conversion result does not start with an '@'" do
     obj = mock("to_str")
     obj.stub!(:to_str).and_return("test")
-    -> { @obj.instance_variable_get(obj) }.should raise_error(NameError)
+    -> { @obj.instance_variable_get(obj) }.should.raise(NameError)
   end
 
   it "raises a NameError when passed just '@'" do
     obj = mock("to_str")
     obj.stub!(:to_str).and_return('@')
-    -> { @obj.instance_variable_get(obj) }.should raise_error(NameError)
+    -> { @obj.instance_variable_get(obj) }.should.raise(NameError)
   end
 end
 
@@ -57,15 +57,21 @@ describe "Kernel#instance_variable_get when passed Symbol" do
   end
 
   it "raises a NameError when passed :@ as an instance variable name" do
-    -> { @obj.instance_variable_get(:"@") }.should raise_error(NameError)
+    -> { @obj.instance_variable_get(:"@") }.should.raise(NameError)
   end
 
   it "raises a NameError when the passed Symbol does not start with an '@'" do
-    -> { @obj.instance_variable_get(:test) }.should raise_error(NameError)
+    -> { @obj.instance_variable_get(:test) }.should.raise(NameError)
   end
 
   it "raises a NameError when the passed Symbol is an invalid instance variable name" do
-    -> { @obj.instance_variable_get(:"@0") }.should raise_error(NameError)
+    -> { @obj.instance_variable_get(:"@0") }.should.raise(NameError)
+  end
+
+  it "returns nil or raises for frozen objects" do
+    nil.instance_variable_get(:@foo).should == nil
+    -> { nil.instance_variable_get(:foo) }.should.raise(NameError)
+    :foo.instance_variable_get(:@foo).should == nil
   end
 end
 
@@ -80,26 +86,26 @@ describe "Kernel#instance_variable_get when passed String" do
   end
 
   it "raises a NameError when the passed String does not start with an '@'" do
-    -> { @obj.instance_variable_get("test") }.should raise_error(NameError)
+    -> { @obj.instance_variable_get("test") }.should.raise(NameError)
   end
 
   it "raises a NameError when the passed String is an invalid instance variable name" do
-    -> { @obj.instance_variable_get("@0") }.should raise_error(NameError)
+    -> { @obj.instance_variable_get("@0") }.should.raise(NameError)
   end
 
   it "raises a NameError when passed '@' as an instance variable name" do
-    -> { @obj.instance_variable_get("@") }.should raise_error(NameError)
+    -> { @obj.instance_variable_get("@") }.should.raise(NameError)
   end
 end
 
-describe "Kernel#instance_variable_get when passed Fixnum" do
+describe "Kernel#instance_variable_get when passed Integer" do
   before :each do
     @obj = Object.new
     @obj.instance_variable_set("@test", :test)
   end
 
   it "raises a TypeError" do
-    -> { @obj.instance_variable_get(10) }.should raise_error(TypeError)
-    -> { @obj.instance_variable_get(-10) }.should raise_error(TypeError)
+    -> { @obj.instance_variable_get(10) }.should.raise(TypeError)
+    -> { @obj.instance_variable_get(-10) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/kernel/instance_variable_set_spec.rb b/spec/ruby/core/kernel/instance_variable_set_spec.rb
index c5a4085530..bf165a824e 100644
--- a/spec/ruby/core/kernel/instance_variable_set_spec.rb
+++ b/spec/ruby/core/kernel/instance_variable_set_spec.rb
@@ -18,26 +18,26 @@ describe "Kernel#instance_variable_set" do
 
   it "raises a NameError exception if the argument is not of form '@x'" do
     no_dog = Class.new
-    -> { no_dog.new.instance_variable_set(:c, "cat") }.should raise_error(NameError)
+    -> { no_dog.new.instance_variable_set(:c, "cat") }.should.raise(NameError)
   end
 
   it "raises a NameError exception if the argument is an invalid instance variable name" do
     digit_dog = Class.new
-    -> { digit_dog.new.instance_variable_set(:"@0", "cat") }.should raise_error(NameError)
+    -> { digit_dog.new.instance_variable_set(:"@0", "cat") }.should.raise(NameError)
   end
 
   it "raises a NameError when the argument is '@'" do
     dog_at = Class.new
-    -> { dog_at.new.instance_variable_set(:"@", "cat") }.should raise_error(NameError)
+    -> { dog_at.new.instance_variable_set(:"@", "cat") }.should.raise(NameError)
   end
 
-  it "raises a TypeError if the instance variable name is a Fixnum" do
-    -> { "".instance_variable_set(1, 2) }.should raise_error(TypeError)
+  it "raises a TypeError if the instance variable name is an Integer" do
+    -> { "".instance_variable_set(1, 2) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the instance variable name is an object that does not respond to to_str" do
     class KernelSpecs::A; end
-    -> { "".instance_variable_set(KernelSpecs::A.new, 3) }.should raise_error(TypeError)
+    -> { "".instance_variable_set(KernelSpecs::A.new, 3) }.should.raise(TypeError)
   end
 
   it "raises a NameError if the passed object, when coerced with to_str, does not start with @" do
@@ -46,11 +46,11 @@ describe "Kernel#instance_variable_set" do
         ":c"
       end
     end
-    -> { "".instance_variable_set(KernelSpecs::B.new, 4) }.should raise_error(NameError)
+    -> { "".instance_variable_set(KernelSpecs::B.new, 4) }.should.raise(NameError)
   end
 
   it "raises a NameError if pass an object that cannot be a symbol" do
-    -> { "".instance_variable_set(:c, 1) }.should raise_error(NameError)
+    -> { "".instance_variable_set(:c, 1) }.should.raise(NameError)
   end
 
   it "accepts as instance variable name any instance of a class that responds to to_str" do
@@ -78,16 +78,28 @@ describe "Kernel#instance_variable_set" do
     end
 
     it "keeps stored object after any exceptions" do
-      -> { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(Exception)
-      @frozen.ivar.should equal(:origin)
+      -> { @frozen.instance_variable_set(:@ivar, :replacement) }.should.raise(Exception)
+      @frozen.ivar.should.equal?(:origin)
     end
 
-    it "raises a #{frozen_error_class} when passed replacement is identical to stored object" do
-      -> { @frozen.instance_variable_set(:@ivar, :origin) }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed replacement is identical to stored object" do
+      -> { @frozen.instance_variable_set(:@ivar, :origin) }.should.raise(FrozenError)
     end
 
-    it "raises a #{frozen_error_class} when passed replacement is different from stored object" do
-      -> { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed replacement is different from stored object" do
+      -> { @frozen.instance_variable_set(:@ivar, :replacement) }.should.raise(FrozenError)
+    end
+
+    it "accepts unicode instance variable names" do
+      o = Object.new
+      o.instance_variable_set(:@💙, 42)
+      o.instance_variable_get(:@💙).should == 42
+    end
+
+    it "raises for frozen objects" do
+      -> { nil.instance_variable_set(:@foo, 42) }.should.raise(FrozenError)
+      -> { nil.instance_variable_set(:foo, 42) }.should.raise(NameError)
+      -> { :foo.instance_variable_set(:@foo, 42) }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/kernel/instance_variables_spec.rb b/spec/ruby/core/kernel/instance_variables_spec.rb
index b6d6e27772..75c1d8f752 100644
--- a/spec/ruby/core/kernel/instance_variables_spec.rb
+++ b/spec/ruby/core/kernel/instance_variables_spec.rb
@@ -4,12 +4,14 @@ require_relative 'fixtures/classes'
 describe "Kernel#instance_variables" do
   describe "immediate values" do
     it "returns an empty array if no instance variables are defined" do
-      0.instance_variables.should == []
+      [0, 0.5, true, false, nil].each do |value|
+        value.instance_variables.should == []
+      end
     end
 
     it "returns the correct array if an instance variable is added" do
       a = 0
-      ->{ a.instance_variable_set("@test", 1) }.should raise_error(RuntimeError)
+      ->{ a.instance_variable_set("@test", 1) }.should.raise(RuntimeError)
     end
   end
 
@@ -23,5 +25,16 @@ describe "Kernel#instance_variables" do
       a.instance_variable_set("@test", 1)
       a.instance_variables.should == [:@test]
     end
+
+    it "returns the instances variables in the order declared" do
+      c = Class.new do
+        def initialize
+          @c = 1
+          @a = 2
+          @b = 3
+        end
+      end
+      c.new.instance_variables.should == [:@c, :@a, :@b]
+    end
   end
 end
diff --git a/spec/ruby/core/kernel/is_a_spec.rb b/spec/ruby/core/kernel/is_a_spec.rb
index dc69766f83..bd8c96529a 100644
--- a/spec/ruby/core/kernel/is_a_spec.rb
+++ b/spec/ruby/core/kernel/is_a_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/kind_of'
 
 describe "Kernel#is_a?" do
-  it_behaves_like :kernel_kind_of , :is_a?
+  it_behaves_like :kernel_kind_of, :is_a?
 end
diff --git a/spec/ruby/core/kernel/iterator_spec.rb b/spec/ruby/core/kernel/iterator_spec.rb
deleted file mode 100644
index 7fbdade9dc..0000000000
--- a/spec/ruby/core/kernel/iterator_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-
-describe "Kernel#iterator?" do
-  it "is a private method" do
-    Kernel.should have_private_instance_method(:iterator?)
-  end
-end
-
-describe "Kernel.iterator?" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/kernel/itself_spec.rb b/spec/ruby/core/kernel/itself_spec.rb
index c906d7c3e8..c1f01fdc5e 100644
--- a/spec/ruby/core/kernel/itself_spec.rb
+++ b/spec/ruby/core/kernel/itself_spec.rb
@@ -4,6 +4,6 @@ require_relative 'fixtures/classes'
 describe "Kernel#itself" do
   it "returns the receiver itself" do
     foo = Object.new
-    foo.itself.should equal foo
+    foo.itself.should.equal? foo
   end
 end
diff --git a/spec/ruby/core/kernel/kind_of_spec.rb b/spec/ruby/core/kernel/kind_of_spec.rb
index 734035620c..c988edccb5 100644
--- a/spec/ruby/core/kernel/kind_of_spec.rb
+++ b/spec/ruby/core/kernel/kind_of_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/kind_of'
 
 describe "Kernel#kind_of?" do
-  it_behaves_like :kernel_kind_of , :kind_of?
+  it_behaves_like :kernel_kind_of, :kind_of?
 end
diff --git a/spec/ruby/core/kernel/lambda_spec.rb b/spec/ruby/core/kernel/lambda_spec.rb
index 4796d65352..6ab89c2bbb 100644
--- a/spec/ruby/core/kernel/lambda_spec.rb
+++ b/spec/ruby/core/kernel/lambda_spec.rb
@@ -8,64 +8,52 @@ describe "Kernel.lambda" do
   it_behaves_like :kernel_lambda, :lambda
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:lambda)
+    Kernel.private_instance_methods(false).should.include?(:lambda)
   end
 
   it "creates a lambda-style Proc if given a literal block" do
     l = lambda { 42 }
-    l.lambda?.should be_true
+    l.lambda?.should == true
   end
 
   it "creates a lambda-style Proc if given a literal block via #send" do
     l = send(:lambda) { 42 }
-    l.lambda?.should be_true
+    l.lambda?.should == true
   end
 
   it "creates a lambda-style Proc if given a literal block via #__send__" do
     l = __send__(:lambda) { 42 }
-    l.lambda?.should be_true
-  end
-
-  it "creates a lambda-style Proc if given a literal block via Kernel.public_send" do
-    l = Kernel.public_send(:lambda) { 42 }
-    l.lambda?.should be_true
-  end
-
-  it "returned the passed Proc if given an existing Proc" do
-    some_proc = proc {}
-    l = lambda(&some_proc)
-    l.should equal(some_proc)
-    l.lambda?.should be_false
+    l.lambda?.should == true
   end
 
   it "checks the arity of the call when no args are specified" do
     l = lambda { :called }
     l.call.should == :called
 
-    lambda { l.call(1) }.should raise_error(ArgumentError)
-    lambda { l.call(1, 2) }.should raise_error(ArgumentError)
+    lambda { l.call(1) }.should.raise(ArgumentError)
+    lambda { l.call(1, 2) }.should.raise(ArgumentError)
   end
 
   it "checks the arity when 1 arg is specified" do
     l = lambda { |a| :called }
     l.call(1).should == :called
 
-    lambda { l.call }.should raise_error(ArgumentError)
-    lambda { l.call(1, 2) }.should raise_error(ArgumentError)
+    lambda { l.call }.should.raise(ArgumentError)
+    lambda { l.call(1, 2) }.should.raise(ArgumentError)
   end
 
   it "does not check the arity when passing a Proc with &" do
     l = lambda { || :called }
     p = proc { || :called }
 
-    lambda { l.call(1) }.should raise_error(ArgumentError)
+    lambda { l.call(1) }.should.raise(ArgumentError)
     p.call(1).should == :called
   end
 
   it "accepts 0 arguments when used with ||" do
     lambda {
       lambda { || }.call(1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "strictly checks the arity when 0 or 2..inf args are specified" do
@@ -73,15 +61,15 @@ describe "Kernel.lambda" do
 
     lambda {
       l.call
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     lambda {
       l.call(1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     lambda {
       l.call(1,2)
-    }.should_not raise_error(ArgumentError)
+    }.should_not.raise(ArgumentError)
   end
 
   it "returns from the lambda itself, not the creation site of the lambda" do
@@ -91,10 +79,32 @@ describe "Kernel.lambda" do
       @reached_end_of_method = true
     end
     test
-    @reached_end_of_method.should be_true
+    @reached_end_of_method.should == true
   end
 
   it "allows long returns to flow through it" do
     KernelSpecs::Lambda.new.outer.should == :good
   end
+
+  it "treats the block as a Proc when lambda is re-defined" do
+    klass = Class.new do
+      def lambda (&block); block; end
+      def ret
+        lambda { return 1 }.call
+        2
+      end
+    end
+    klass.new.lambda { 42 }.should.instance_of? Proc
+    klass.new.ret.should == 1
+  end
+
+  context "when called without a literal block" do
+    it "raises when proc isn't a lambda" do
+      -> { lambda(&proc{}) }.should.raise(ArgumentError, /the lambda method requires a literal block/)
+    end
+
+    it "doesn't warn when proc is lambda" do
+      -> { lambda(&lambda{}) }.should_not complain(verbose: true)
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/load_spec.rb b/spec/ruby/core/kernel/load_spec.rb
index a165cc4acd..890aab8c27 100644
--- a/spec/ruby/core/kernel/load_spec.rb
+++ b/spec/ruby/core/kernel/load_spec.rb
@@ -13,7 +13,7 @@ describe "Kernel#load" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:load)
+    Kernel.private_instance_methods(false).should.include?(:load)
   end
 
   it_behaves_like :kernel_require_basic, :load, CodeLoadingSpecs::Method.new
diff --git a/spec/ruby/core/kernel/local_variables_spec.rb b/spec/ruby/core/kernel/local_variables_spec.rb
index d0f09943bd..40c343f7e4 100644
--- a/spec/ruby/core/kernel/local_variables_spec.rb
+++ b/spec/ruby/core/kernel/local_variables_spec.rb
@@ -7,14 +7,13 @@ describe "Kernel#local_variables" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:local_variables)
+    Kernel.private_instance_methods(false).should.include?(:local_variables)
   end
 
   it "contains locals as they are added" do
     a = 1
     b = 2
-    local_variables.should include(:a, :b)
-    local_variables.length.should == 2
+    local_variables.sort.should == [:a, :b]
   end
 
   it "is accessible from bindings" do
@@ -25,13 +24,22 @@ describe "Kernel#local_variables" do
     end
     foo_binding = local_var_foo()
     res = eval("local_variables",foo_binding)
-    res.should include(:a, :b)
-    res.length.should == 2
+    res.sort.should == [:a, :b]
   end
 
   it "is accessible in eval" do
     eval "a=1; b=2; ScratchPad.record local_variables"
-    ScratchPad.recorded.should include(:a, :b)
-    ScratchPad.recorded.length.should == 2
+    ScratchPad.recorded.sort.should == [:a, :b]
+  end
+
+  it "includes only unique variable names" do
+    def local_var_method
+      a = 1
+      1.times do |;a|
+        return local_variables
+      end
+    end
+
+    local_var_method.should == [:a]
   end
 end
diff --git a/spec/ruby/core/kernel/loop_spec.rb b/spec/ruby/core/kernel/loop_spec.rb
index 7c76c7d28e..c2976e5cc5 100644
--- a/spec/ruby/core/kernel/loop_spec.rb
+++ b/spec/ruby/core/kernel/loop_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel.loop" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:loop)
+    Kernel.private_instance_methods(false).should.include?(:loop)
   end
 
   it "calls block until it is terminated by a break" do
@@ -30,7 +30,7 @@ describe "Kernel.loop" do
 
   it "returns an enumerator if no block given" do
     enum = loop
-    enum.instance_of?(Enumerator).should be_true
+    enum.instance_of?(Enumerator).should == true
     cnt = 0
     enum.each do |*args|
       raise "Args should be empty #{args.inspect}" unless args.empty?
@@ -55,7 +55,7 @@ describe "Kernel.loop" do
   end
 
   it "does not rescue other errors" do
-    ->{ loop do raise StandardError end }.should raise_error( StandardError )
+    ->{ loop do raise StandardError end }.should.raise( StandardError )
   end
 
   it "returns StopIteration#result, the result value of a finished iterator" do
diff --git a/spec/ruby/core/kernel/match_spec.rb b/spec/ruby/core/kernel/match_spec.rb
index 6dc1eb7de8..cd6330fe91 100644
--- a/spec/ruby/core/kernel/match_spec.rb
+++ b/spec/ruby/core/kernel/match_spec.rb
@@ -1,24 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Kernel#=~" do
-  it "returns nil matching any object" do
-    o = Object.new
-
-    suppress_warning do
-      (o =~ /Object/).should   be_nil
-      (o =~ 'Object').should   be_nil
-      (o =~ Object).should     be_nil
-      (o =~ Object.new).should be_nil
-      (o =~ nil).should        be_nil
-      (o =~ true).should       be_nil
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "is deprecated" do
-      -> do
-        Object.new =~ /regexp/
-      end.should complain(/deprecated Object#=~ is called on Object/, verbose: true)
-    end
+  it "is no longer defined" do
+    Object.new.should_not.respond_to?(:=~)
   end
 end
diff --git a/spec/ruby/core/kernel/method_spec.rb b/spec/ruby/core/kernel/method_spec.rb
index 25c6691e10..9187b8c7e7 100644
--- a/spec/ruby/core/kernel/method_spec.rb
+++ b/spec/ruby/core/kernel/method_spec.rb
@@ -11,12 +11,12 @@ describe "Kernel#method" do
 
   it "can be called on a private method" do
     @obj.send(:private_method).should == :private_method
-    @obj.method(:private_method).should be_an_instance_of(Method)
+    @obj.method(:private_method).should.instance_of?(Method)
   end
 
   it "can be called on a protected method" do
     @obj.send(:protected_method).should == :protected_method
-    @obj.method(:protected_method).should be_an_instance_of(Method)
+    @obj.method(:protected_method).should.instance_of?(Method)
   end
 
   it "will see an alias of the original method as == when in a derived class" do
@@ -29,9 +29,60 @@ describe "Kernel#method" do
     m.call.should == :defined
   end
 
-  it "can be called even if we only repond_to_missing? method, true" do
+  it "can be called even if we only respond_to_missing? method, true" do
     m = KernelSpecs::RespondViaMissing.new.method(:handled_privately)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call(1, 2, 3).should == "Done handled_privately([1, 2, 3])"
   end
+
+  it "can call a #method_missing accepting zero or one arguments" do
+    cls = Class.new do
+      def respond_to_missing?(name, *)
+        name == :foo or super
+      end
+      def method_missing
+        :no_args
+      end
+    end
+    m = cls.new.method(:foo)
+    -> { m.call }.should.raise(ArgumentError)
+
+    cls = Class.new do
+      def respond_to_missing?(name, *)
+        name == :bar or super
+      end
+      def method_missing(m)
+        m
+      end
+    end
+    m = cls.new.method(:bar)
+    m.call.should == :bar
+  end
+
+  describe "converts the given name to a String using #to_str" do
+    it "calls #to_str to convert the given name to a String" do
+      name = mock("method-name")
+      name.should_receive(:to_str).and_return("hash")
+      Object.method(name).should == Object.method(:hash)
+    end
+
+    it "raises a TypeError if the given name can't be converted to a String" do
+      -> { Object.method(nil) }.should.raise(TypeError)
+      -> { Object.method([])  }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to a String" do
+      name = mock("method-name")
+      name.should_receive(:to_str).and_raise(NoMethodError)
+      -> { Object.method(name) }.should.raise(NoMethodError)
+
+      name = mock("method-name")
+      name.should_receive(:to_str).and_raise(NoMethodError)
+      begin
+        raise RuntimeError.new
+      rescue => cause
+        -> { Object.method(name) }.should.raise(NoMethodError, cause:)
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/methods_spec.rb b/spec/ruby/core/kernel/methods_spec.rb
index fb7a7e8be9..cfa22aa05a 100644
--- a/spec/ruby/core/kernel/methods_spec.rb
+++ b/spec/ruby/core/kernel/methods_spec.rb
@@ -5,67 +5,67 @@ require_relative '../../fixtures/reflection'
 # TODO: rewrite
 describe "Kernel#methods" do
   it "returns singleton methods defined by obj.meth" do
-    KernelSpecs::Methods.methods(false).should include(:ichi)
+    KernelSpecs::Methods.methods(false).should.include?(:ichi)
   end
 
   it "returns singleton methods defined in 'class << self'" do
-    KernelSpecs::Methods.methods(false).should include(:san)
+    KernelSpecs::Methods.methods(false).should.include?(:san)
   end
 
   it "returns private singleton methods defined by obj.meth" do
-    KernelSpecs::Methods.methods(false).should include(:shi)
+    KernelSpecs::Methods.methods(false).should.include?(:shi)
   end
 
   it "returns singleton methods defined in 'class << self' when it follows 'private'" do
-    KernelSpecs::Methods.methods(false).should include(:roku)
+    KernelSpecs::Methods.methods(false).should.include?(:roku)
   end
 
   it "does not return private singleton methods defined in 'class << self'" do
-    KernelSpecs::Methods.methods(false).should_not include(:shichi)
+    KernelSpecs::Methods.methods(false).should_not.include?(:shichi)
   end
 
   it "returns the publicly accessible methods of the object" do
     meths =  KernelSpecs::Methods.methods(false)
-    meths.should include(:hachi, :ichi, :juu, :juu_ichi,
-                         :juu_ni, :roku, :san, :shi)
+    meths.to_set.should >= Set[:hachi, :ichi, :juu, :juu_ichi,
+                               :juu_ni, :roku, :san, :shi]
 
     KernelSpecs::Methods.new.methods(false).should == []
   end
 
   it "returns the publicly accessible methods in the object, its ancestors and mixed-in modules" do
     meths = KernelSpecs::Methods.methods(false) & KernelSpecs::Methods.methods
-    meths.should include(:hachi, :ichi, :juu, :juu_ichi,
-                         :juu_ni, :roku, :san, :shi)
+    meths.to_set.should >= Set[:hachi, :ichi, :juu, :juu_ichi,
+                               :juu_ni, :roku, :san, :shi]
 
-    KernelSpecs::Methods.new.methods.should include(:ku, :ni, :juu_san)
+    KernelSpecs::Methods.new.methods.to_set.should >= Set[:ku, :ni, :juu_san]
   end
 
   it "returns methods added to the metaclass through extend" do
     meth = KernelSpecs::Methods.new
-    meth.methods.should_not include(:peekaboo)
+    meth.methods.should_not.include?(:peekaboo)
     meth.extend(KernelSpecs::Methods::MetaclassMethods)
-    meth.methods.should include(:peekaboo)
+    meth.methods.should.include?(:peekaboo)
   end
 
   it "does not return undefined singleton methods defined by obj.meth" do
     o = KernelSpecs::Child.new
     def o.single; end
-    o.methods.should include(:single)
+    o.methods.should.include?(:single)
 
     class << o; self; end.send :undef_method, :single
-    o.methods.should_not include(:single)
+    o.methods.should_not.include?(:single)
   end
 
   it "does not return superclass methods undefined in the object's class" do
-    KernelSpecs::Child.new.methods.should_not include(:parent_method)
+    KernelSpecs::Child.new.methods.should_not.include?(:parent_method)
   end
 
   it "does not return superclass methods undefined in a superclass" do
-    KernelSpecs::Grandchild.new.methods.should_not include(:parent_method)
+    KernelSpecs::Grandchild.new.methods.should_not.include?(:parent_method)
   end
 
   it "does not return included module methods undefined in the object's class" do
-    KernelSpecs::Grandchild.new.methods.should_not include(:parent_mixin_method)
+    KernelSpecs::Grandchild.new.methods.should_not.include?(:parent_mixin_method)
   end
 end
 
diff --git a/spec/ruby/core/kernel/nil_spec.rb b/spec/ruby/core/kernel/nil_spec.rb
index b63705f7bc..7418245f26 100644
--- a/spec/ruby/core/kernel/nil_spec.rb
+++ b/spec/ruby/core/kernel/nil_spec.rb
@@ -1,6 +1,12 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe "Kernel#nil?" do
-  it "needs to be reviewed for spec completeness"
+describe 'Kernel#nil?' do
+  it 'returns false' do
+    Object.should_not.nil?
+    Object.new.should_not.nil?
+    ''.should_not.nil?
+    [].should_not.nil?
+    {}.should_not.nil?
+  end
 end
diff --git a/spec/ruby/core/kernel/not_match_spec.rb b/spec/ruby/core/kernel/not_match_spec.rb
index 906f18df2c..4ed7ea7b42 100644
--- a/spec/ruby/core/kernel/not_match_spec.rb
+++ b/spec/ruby/core/kernel/not_match_spec.rb
@@ -14,6 +14,10 @@ describe "Kernel#!~" do
     (obj !~ :foo).should == false
   end
 
+  it "raises NoMethodError if self does not respond to #=~" do
+    -> { Object.new !~ :foo }.should.raise(NoMethodError)
+  end
+
   it 'can be overridden in subclasses' do
     obj = KernelSpecs::NotMatch.new
     (obj !~ :bar).should == :foo
diff --git a/spec/ruby/core/kernel/open_spec.rb b/spec/ruby/core/kernel/open_spec.rb
index 981b5291b3..14a3c43cad 100644
--- a/spec/ruby/core/kernel/open_spec.rb
+++ b/spec/ruby/core/kernel/open_spec.rb
@@ -2,7 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#open" do
-
   before :each do
     @name = tmp("kernel_open.txt")
     @content = "This is a test"
@@ -16,61 +15,90 @@ describe "Kernel#open" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:open)
+    Kernel.private_instance_methods(false).should.include?(:open)
   end
 
   it "opens a file when given a valid filename" do
     @file = open(@name)
-    @file.should be_kind_of(File)
+    @file.should.is_a?(File)
   end
 
   it "opens a file when called with a block" do
     open(@name, "r") { |f| f.gets }.should == @content
   end
 
-  platform_is_not :windows do
-    it "opens an io when path starts with a pipe" do
-      @io = open("|date")
-      begin
-        @io.should be_kind_of(IO)
-        @io.read
-      ensure
-        @io.close
+  ruby_version_is ""..."4.0" do
+    platform_is_not :windows, :wasi do
+      it "opens an io when path starts with a pipe" do
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          @io = open("|date")
+        end
+        begin
+          @io.should.is_a?(IO)
+          @io.read
+        ensure
+          @io.close
+        end
       end
-    end
 
-    it "opens an io when called with a block" do
-      @output = open("|date") { |f| f.read }
-      @output.should_not == ''
-    end
+      it "opens an io when called with a block" do
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          @output = open("|date") { |f| f.read }
+        end
+        @output.should_not == ''
+      end
 
-    it "opens an io for writing" do
-      -> do
-        bytes = open("|cat", "w") { |io| io.write(".") }
-        bytes.should == 1
-      end.should output_to_fd(".")
+      it "opens an io for writing" do
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          -> {
+            bytes = open("|cat", "w") { |io| io.write(".") }
+            bytes.should == 1
+          }.should output_to_fd(".")
+        end
+      end
     end
-  end
 
-  platform_is :windows do
-    it "opens an io when path starts with a pipe" do
-      @io = open("|date /t")
-      begin
-        @io.should be_kind_of(IO)
-        @io.read
-      ensure
-        @io.close
+    platform_is :windows do
+      it "opens an io when path starts with a pipe" do
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          @io = open("|date /t")
+        end
+        begin
+          @io.should.is_a?(IO)
+          @io.read
+        ensure
+          @io.close
+        end
+      end
+
+      it "opens an io when called with a block" do
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          @output = open("|date /t") { |f| f.read }
+        end
+        @output.should_not == ''
       end
     end
 
-    it "opens an io when called with a block" do
-      @output = open("|date /t") { |f| f.read }
-      @output.should_not == ''
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation given a path with a pipe" do
+      cmd = "|echo ok"
+      -> {
+        open(cmd) { |f| f.read }
+      }.should complain(/Kernel#open with a leading '\|'/)
     end
   end
 
   it "raises an ArgumentError if not passed one argument" do
-    -> { open }.should raise_error(ArgumentError)
+    -> { open }.should.raise(ArgumentError)
+  end
+
+  it "accepts options as keyword arguments" do
+    @file = open(@name, "r", 0666, flags: File::CREAT)
+    @file.should.is_a?(File)
+
+    -> {
+      open(@name, "r", 0666, {flags: File::CREAT})
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 1..3)")
   end
 
   describe "when given an object that responds to to_open" do
@@ -78,7 +106,7 @@ describe "Kernel#open" do
       ScratchPad.clear
     end
 
-    it "calls #to_path to covert the argument to a String before calling #to_str" do
+    it "calls #to_path to convert the argument to a String before calling #to_str" do
       obj = mock("open to_path")
       obj.should_receive(:to_path).at_least(1).times.and_return(@name)
       obj.should_not_receive(:to_str)
@@ -98,7 +126,7 @@ describe "Kernel#open" do
       @file = File.open(@name)
       obj.should_receive(:to_open).and_return(@file)
       @file = open(obj)
-      @file.should be_kind_of(File)
+      @file.should.is_a?(File)
     end
 
     it "returns the value from #to_open" do
@@ -110,11 +138,21 @@ describe "Kernel#open" do
 
     it "passes its arguments onto #to_open" do
       obj = mock('to_open')
-      obj.should_receive(:to_open).with(1,2,3)
-
+      obj.should_receive(:to_open).with(1, 2, 3)
       open(obj, 1, 2, 3)
     end
 
+    it "passes keyword arguments onto #to_open as keyword arguments if to_open accepts them" do
+      obj = Object.new
+      def obj.to_open(*args, **kw)
+        ScratchPad << {args: args, kw: kw}
+      end
+
+      ScratchPad.record []
+      open(obj, 1, 2, 3, a: "b")
+      ScratchPad.recorded.should == [args: [1, 2, 3], kw: {a: "b"}]
+    end
+
     it "passes the return value from #to_open to a block" do
       obj = mock('to_open')
       obj.should_receive(:to_open).and_return(:value)
@@ -129,14 +167,24 @@ describe "Kernel#open" do
 
   it "raises a TypeError if passed a non-String that does not respond to #to_open" do
     obj = mock('non-fileish')
-    -> { open(obj) }.should raise_error(TypeError)
-    -> { open(nil) }.should raise_error(TypeError)
-    -> { open(7)   }.should raise_error(TypeError)
+    -> { open(obj) }.should.raise(TypeError)
+    -> { open(nil) }.should.raise(TypeError)
+    -> { open(7)   }.should.raise(TypeError)
   end
 
   it "accepts nil for mode and permission" do
     open(@name, nil, nil) { |f| f.gets }.should == @content
   end
+
+  it "is not redefined by open-uri" do
+    code = <<~RUBY
+      before = Kernel.instance_method(:open)
+      require 'open-uri'
+      after = Kernel.instance_method(:open)
+      p before == after
+    RUBY
+    ruby_exe(code, args: "2>&1").should == "true\n"
+  end
 end
 
 describe "Kernel.open" do
diff --git a/spec/ruby/core/kernel/p_spec.rb b/spec/ruby/core/kernel/p_spec.rb
index 798bd47b34..f89716899a 100644
--- a/spec/ruby/core/kernel/p_spec.rb
+++ b/spec/ruby/core/kernel/p_spec.rb
@@ -13,7 +13,7 @@ describe "Kernel#p" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:p)
+    Kernel.private_instance_methods(false).should.include?(:p)
   end
 
   # TODO: fix
@@ -57,10 +57,14 @@ describe "Kernel#p" do
     }
     -> { p(o) }.should output_to_fd("Next time, Gadget, NEXT TIME!\n")
 
-    $\ = " *helicopter sound*\n"
+    suppress_warning {
+      $\ = " *helicopter sound*\n"
+    }
     -> { p(o) }.should output_to_fd("Next time, Gadget, NEXT TIME!\n")
 
-    $/ = " *helicopter sound*\n"
+    suppress_warning {
+      $/ = " *helicopter sound*\n"
+    }
     -> { p(o) }.should output_to_fd("Next time, Gadget, NEXT TIME!\n")
   end
 
@@ -72,10 +76,8 @@ describe "Kernel#p" do
     -> { p(*[]) }.should output("")
   end
 
-=begin Not sure how to spec this, but wanted to note the behavior here
-  it "does not flush if receiver is not a TTY or a File" do
-  end
-=end
+  # Not sure how to spec this, but wanted to note the behavior here
+  it "does not flush if receiver is not a TTY or a File"
 end
 
 describe "Kernel.p" do
diff --git a/spec/ruby/core/kernel/pp_spec.rb b/spec/ruby/core/kernel/pp_spec.rb
index e19dc64caf..b5b1c98d38 100644
--- a/spec/ruby/core/kernel/pp_spec.rb
+++ b/spec/ruby/core/kernel/pp_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.5" do
-  describe "Kernel#pp" do
-    it "lazily loads the 'pp' library and delegates the call to that library" do
-      # Run in child process to ensure 'pp' hasn't been loaded yet.
-      output = ruby_exe("pp [1, 2, 3]")
-      output.should == "[1, 2, 3]\n"
-    end
+describe "Kernel#pp" do
+  it "lazily loads the 'pp' library and delegates the call to that library" do
+    # Run in child process to ensure 'pp' hasn't been loaded yet.
+    output = ruby_exe("pp [1, 2, 3]")
+    output.should == "[1, 2, 3]\n"
   end
 end
diff --git a/spec/ruby/core/kernel/print_spec.rb b/spec/ruby/core/kernel/print_spec.rb
index c8c4453d1e..5473d22f71 100644
--- a/spec/ruby/core/kernel/print_spec.rb
+++ b/spec/ruby/core/kernel/print_spec.rb
@@ -3,7 +3,19 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#print" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:print)
+    Kernel.private_instance_methods(false).should.include?(:print)
+  end
+
+  it "delegates to $stdout" do
+    -> { print :arg }.should output("arg")
+  end
+
+  it "prints $_ when no arguments are given" do
+    orig_value = $_
+    $_ = 'foo'
+    -> { print }.should output("foo")
+  ensure
+    $_ = orig_value
   end
 end
 
diff --git a/spec/ruby/core/kernel/printf_spec.rb b/spec/ruby/core/kernel/printf_spec.rb
index 5d68c0a13c..50939b3794 100644
--- a/spec/ruby/core/kernel/printf_spec.rb
+++ b/spec/ruby/core/kernel/printf_spec.rb
@@ -1,16 +1,14 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/sprintf'
-require "stringio"
 
 describe "Kernel#printf" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:printf)
+    Kernel.private_instance_methods(false).should.include?(:printf)
   end
 end
 
 describe "Kernel.printf" do
-
   before :each do
     @stdout = $stdout
     @name = tmp("kernel_puts.txt")
@@ -34,11 +32,24 @@ describe "Kernel.printf" do
     Kernel.printf(object, "%s", "string")
   end
 
+  it "calls #to_str to convert the format object to a String" do
+    object = mock('format string')
+    object.should_receive(:to_str).and_return("to_str: %i")
+    $stdout.should_receive(:write).with("to_str: 42")
+    Kernel.printf($stdout, object, 42)
+  end
+end
+
+describe "Kernel.printf" do
   describe "formatting" do
+    before :each do
+      require "stringio"
+    end
+
     context "io is specified" do
       it_behaves_like :kernel_sprintf, -> format, *args {
-        io = StringIO.new
-        printf(io, format, *args)
+        io = StringIO.new(+"")
+        Kernel.printf(io, format, *args)
         io.string
       }
     end
@@ -46,10 +57,9 @@ describe "Kernel.printf" do
     context "io is not specified" do
       it_behaves_like :kernel_sprintf, -> format, *args {
         stdout = $stdout
-
         begin
-          $stdout = io = StringIO.new
-          printf(format, *args)
+          $stdout = io = StringIO.new(+"")
+          Kernel.printf(format, *args)
           io.string
         ensure
           $stdout = stdout
diff --git a/spec/ruby/core/kernel/private_methods_spec.rb b/spec/ruby/core/kernel/private_methods_spec.rb
index 041634d1e5..b0e6d042a9 100644
--- a/spec/ruby/core/kernel/private_methods_spec.rb
+++ b/spec/ruby/core/kernel/private_methods_spec.rb
@@ -6,23 +6,23 @@ require_relative '../../fixtures/reflection'
 describe "Kernel#private_methods" do
   it "returns a list of the names of privately accessible methods in the object" do
     m = KernelSpecs::Methods.private_methods(false)
-    m.should include(:shichi)
+    m.should.include?(:shichi)
     m = KernelSpecs::Methods.new.private_methods(false)
-    m.should include(:juu_shi)
+    m.should.include?(:juu_shi)
   end
 
   it "returns a list of the names of privately accessible methods in the object and its ancestors and mixed-in modules" do
     m = (KernelSpecs::Methods.private_methods(false) & KernelSpecs::Methods.private_methods)
 
-    m.should include(:shichi)
+    m.should.include?(:shichi)
     m = KernelSpecs::Methods.new.private_methods
-    m.should include(:juu_shi)
+    m.should.include?(:juu_shi)
   end
 
   it "returns private methods mixed in to the metaclass" do
     m = KernelSpecs::Methods.new
     m.extend(KernelSpecs::Methods::MetaclassMethods)
-    m.private_methods.should include(:shoo)
+    m.private_methods.should.include?(:shoo)
   end
 end
 
diff --git a/spec/ruby/core/kernel/proc_spec.rb b/spec/ruby/core/kernel/proc_spec.rb
index ded2cec3fd..1ba662177b 100644
--- a/spec/ruby/core/kernel/proc_spec.rb
+++ b/spec/ruby/core/kernel/proc_spec.rb
@@ -6,20 +6,20 @@ require_relative 'shared/lambda'
 
 describe "Kernel.proc" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:proc)
+    Kernel.private_instance_methods(false).should.include?(:proc)
   end
 
   it "creates a proc-style Proc if given a literal block" do
     l = proc { 42 }
-    l.lambda?.should be_false
+    l.lambda?.should == false
   end
 
   it "returned the passed Proc if given an existing Proc" do
     some_lambda = -> {}
-    some_lambda.lambda?.should be_true
+    some_lambda.lambda?.should == true
     l = proc(&some_lambda)
-    l.should equal(some_lambda)
-    l.lambda?.should be_true
+    l.should.equal?(some_lambda)
+    l.lambda?.should == true
   end
 
   it_behaves_like :kernel_lambda, :proc
@@ -31,32 +31,18 @@ describe "Kernel.proc" do
       @reached_end_of_method = true
     end
     test
-    @reached_end_of_method.should be_nil
+    @reached_end_of_method.should == nil
   end
 end
 
 describe "Kernel#proc" do
-  ruby_version_is ""..."2.7" do
-    it "uses the implicit block from an enclosing method" do
-      def some_method
-        proc
-      end
-
-      prc = some_method { "hello" }
-
-      prc.call.should == "hello"
-    end
+  def some_method
+    proc
   end
 
-  ruby_version_is "2.7" do
-    it "can be created when called with no block" do
-      def some_method
-        proc
-      end
-
-      -> {
-        some_method { "hello" }
-      }.should complain(/Capturing the given block using Proc.new is deprecated/)
-    end
+  it "raises an ArgumentError when passed no block" do
+    -> {
+      some_method { "hello" }
+    }.should.raise(ArgumentError, 'tried to create Proc object without a block')
   end
 end
diff --git a/spec/ruby/core/kernel/protected_methods_spec.rb b/spec/ruby/core/kernel/protected_methods_spec.rb
index d3334e886b..aecb9f5ffb 100644
--- a/spec/ruby/core/kernel/protected_methods_spec.rb
+++ b/spec/ruby/core/kernel/protected_methods_spec.rb
@@ -8,21 +8,21 @@ require_relative '../../fixtures/reflection'
 # You should use have_protected_method() with the exception of this spec.
 describe "Kernel#protected_methods" do
   it "returns a list of the names of protected methods accessible in the object" do
-    KernelSpecs::Methods.protected_methods(false).sort.should include(:juu_ichi)
-    KernelSpecs::Methods.new.protected_methods(false).should include(:ku)
+    KernelSpecs::Methods.protected_methods(false).sort.should.include?(:juu_ichi)
+    KernelSpecs::Methods.new.protected_methods(false).should.include?(:ku)
   end
 
   it "returns a list of the names of protected methods accessible in the object and from its ancestors and mixed-in modules" do
     l1 = KernelSpecs::Methods.protected_methods(false)
     l2 = KernelSpecs::Methods.protected_methods
-    (l1 & l2).should include(:juu_ichi)
-    KernelSpecs::Methods.new.protected_methods.should include(:ku)
+    (l1 & l2).should.include?(:juu_ichi)
+    KernelSpecs::Methods.new.protected_methods.should.include?(:ku)
   end
 
   it "returns methods mixed in to the metaclass" do
     m = KernelSpecs::Methods.new
     m.extend(KernelSpecs::Methods::MetaclassMethods)
-    m.protected_methods.should include(:nopeeking)
+    m.protected_methods.should.include?(:nopeeking)
   end
 end
 
diff --git a/spec/ruby/core/kernel/public_method_spec.rb b/spec/ruby/core/kernel/public_method_spec.rb
index c5d54c777e..42b8f797d3 100644
--- a/spec/ruby/core/kernel/public_method_spec.rb
+++ b/spec/ruby/core/kernel/public_method_spec.rb
@@ -13,20 +13,20 @@ describe "Kernel#public_method" do
     @obj.send(:private_method).should == :private_method
     -> do
       @obj.public_method(:private_method)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError when called on a protected method" do
     @obj.send(:protected_method).should == :protected_method
     -> {
       @obj.public_method(:protected_method)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "raises a NameError if we only repond_to_missing? method, true" do
     obj = KernelSpecs::RespondViaMissing.new
     -> do
       obj.public_method(:handled_privately)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/kernel/public_methods_spec.rb b/spec/ruby/core/kernel/public_methods_spec.rb
index a5512784fb..e334ac9a55 100644
--- a/spec/ruby/core/kernel/public_methods_spec.rb
+++ b/spec/ruby/core/kernel/public_methods_spec.rb
@@ -5,31 +5,30 @@ require_relative '../../fixtures/reflection'
 # TODO: rewrite
 describe "Kernel#public_methods" do
   it "returns a list of the names of publicly accessible methods in the object" do
-    KernelSpecs::Methods.public_methods(false).sort.should include(:hachi,
-      :ichi, :juu, :juu_ni, :roku, :san, :shi)
-    KernelSpecs::Methods.new.public_methods(false).sort.should include(:juu_san, :ni)
+    KernelSpecs::Methods.public_methods(false).to_set.should >= Set[:hachi, :ichi, :juu, :juu_ni, :roku, :san, :shi]
+    KernelSpecs::Methods.new.public_methods(false).to_set.should >= Set[:juu_san, :ni]
   end
 
   it "returns a list of names without protected accessible methods in the object" do
-    KernelSpecs::Methods.public_methods(false).sort.should_not include(:juu_ichi)
-    KernelSpecs::Methods.new.public_methods(false).sort.should_not include(:ku)
+    KernelSpecs::Methods.public_methods(false).sort.should_not.include?(:juu_ichi)
+    KernelSpecs::Methods.new.public_methods(false).sort.should_not.include?(:ku)
   end
 
   it "returns a list of the names of publicly accessible methods in the object and its ancestors and mixed-in modules" do
-    (KernelSpecs::Methods.public_methods(false) & KernelSpecs::Methods.public_methods).sort.should include(
-      :hachi, :ichi, :juu, :juu_ni, :roku, :san, :shi)
+    (KernelSpecs::Methods.public_methods(false) & KernelSpecs::Methods.public_methods).to_set.should >= Set[
+      :hachi, :ichi, :juu, :juu_ni, :roku, :san, :shi]
     m = KernelSpecs::Methods.new.public_methods
-    m.should include(:ni, :juu_san)
+    m.to_set.should >= Set[:ni, :juu_san]
   end
 
   it "returns methods mixed in to the metaclass" do
     m = KernelSpecs::Methods.new
     m.extend(KernelSpecs::Methods::MetaclassMethods)
-    m.public_methods.should include(:peekaboo)
+    m.public_methods.should.include?(:peekaboo)
   end
 
   it "returns public methods for immediates" do
-    10.public_methods.should include(:divmod)
+    10.public_methods.should.include?(:divmod)
   end
 end
 
diff --git a/spec/ruby/core/kernel/public_send_spec.rb b/spec/ruby/core/kernel/public_send_spec.rb
index 6b942a2e4b..6a4a969c77 100644
--- a/spec/ruby/core/kernel/public_send_spec.rb
+++ b/spec/ruby/core/kernel/public_send_spec.rb
@@ -29,7 +29,7 @@ describe "Kernel#public_send" do
         'done'
       end
     end
-    -> { KernelSpecs::Foo.new.public_send(:bar)}.should raise_error(NoMethodError)
+    -> { KernelSpecs::Foo.new.public_send(:bar)}.should.raise(NoMethodError)
   end
 
   it "raises a NoMethodError if the named method is private" do
@@ -41,7 +41,7 @@ describe "Kernel#public_send" do
     end
     -> {
       KernelSpecs::Foo.new.public_send(:bar)
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   context 'called from own public method' do
@@ -70,11 +70,11 @@ describe "Kernel#public_send" do
     end
 
     it "raises a NoMethodError if the method is protected" do
-      -> { @receiver.call_protected_method }.should raise_error(NoMethodError)
+      -> { @receiver.call_protected_method }.should.raise(NoMethodError)
     end
 
     it "raises a NoMethodError if the method is private" do
-      -> { @receiver.call_private_method }.should raise_error(NoMethodError)
+      -> { @receiver.call_private_method }.should.raise(NoMethodError)
     end
   end
 
@@ -88,7 +88,7 @@ describe "Kernel#public_send" do
     end
     -> {
       KernelSpecs::Foo.new.public_send(:aka)
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   it "raises a NoMethodError if the named method is an alias of a protected method" do
@@ -101,7 +101,15 @@ describe "Kernel#public_send" do
     end
     -> {
       KernelSpecs::Foo.new.public_send(:aka)
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
+  end
+
+  it "includes `public_send` in the backtrace when passed not enough arguments" do
+    -> { public_send() }.should.raise(ArgumentError) { |e| e.backtrace[0].should =~ /[`'](?:Kernel#)?public_send'/ }
+  end
+
+  it "includes `public_send` in the backtrace when passed a single incorrect argument" do
+    -> { public_send(Object.new) }.should.raise(TypeError) { |e| e.backtrace[0].should =~ /[`'](?:Kernel#)?public_send'/ }
   end
 
   it_behaves_like :basicobject_send, :public_send
diff --git a/spec/ruby/core/kernel/putc_spec.rb b/spec/ruby/core/kernel/putc_spec.rb
index 74bd3765db..e6a20a9af1 100644
--- a/spec/ruby/core/kernel/putc_spec.rb
+++ b/spec/ruby/core/kernel/putc_spec.rb
@@ -4,7 +4,7 @@ require_relative '../../shared/io/putc'
 
 describe "Kernel#putc" do
   it "is a private instance method" do
-    Kernel.should have_private_instance_method(:putc)
+    Kernel.private_instance_methods(false).should.include?(:putc)
   end
 end
 
diff --git a/spec/ruby/core/kernel/puts_spec.rb b/spec/ruby/core/kernel/puts_spec.rb
index 6eb38e8fcf..eed18fcd50 100644
--- a/spec/ruby/core/kernel/puts_spec.rb
+++ b/spec/ruby/core/kernel/puts_spec.rb
@@ -15,7 +15,7 @@ describe "Kernel#puts" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:puts)
+    Kernel.private_instance_methods(false).should.include?(:puts)
   end
 
   it "delegates to $stdout.puts" do
diff --git a/spec/ruby/core/kernel/raise_spec.rb b/spec/ruby/core/kernel/raise_spec.rb
index bf26560246..6162677e17 100644
--- a/spec/ruby/core/kernel/raise_spec.rb
+++ b/spec/ruby/core/kernel/raise_spec.rb
@@ -4,14 +4,219 @@ require_relative '../../shared/kernel/raise'
 
 describe "Kernel#raise" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:raise)
+    Kernel.private_instance_methods.should.include?(:raise)
   end
+
+  # Shared specs expect a public #raise method.
+  public_raiser = Object.new
+  class << public_raiser
+    public :raise
+  end
+  it_behaves_like :kernel_raise, :raise, public_raiser
+  it_behaves_like :kernel_raise_with_cause, :raise, public_raiser
 end
 
-describe "Kernel#raise" do
-  it_behaves_like :kernel_raise, :raise, Kernel
+describe "Kernel#raise with previously rescued exception" do
+  it "re-raises the previously rescued exception if no exception is specified" do
+    ScratchPad.record nil
+
+    -> do
+      begin
+        raise Exception, "outer"
+        ScratchPad.record :no_abort
+      rescue Exception
+        begin
+          raise StandardError, "inner"
+        rescue StandardError
+        end
+
+        raise
+        ScratchPad.record :no_reraise
+      end
+    end.should.raise(Exception, "outer")
+
+    ScratchPad.recorded.should == nil
+  end
+
+  it "re-raises a previously rescued exception without overwriting the cause" do
+    begin
+      begin
+        begin
+          begin
+            raise "Error 1"
+          rescue => e1
+            raise "Error 2"
+          end
+        rescue => e2
+          raise "Error 3"
+        end
+      rescue
+        e2.cause.should == e1
+        raise e2
+      end
+    rescue => e
+      e.cause.should == e1
+    end
+  end
+
+  it "re-raises a previously rescued exception with overwriting the cause when it's explicitly specified with :cause option" do
+    e4 = RuntimeError.new("Error 4")
+
+    begin
+      begin
+        begin
+          begin
+            raise "Error 1"
+          rescue => e1
+            raise "Error 2"
+          end
+        rescue => e2
+          raise "Error 3"
+        end
+      rescue
+        e2.cause.should == e1
+        raise e2, cause: e4
+      end
+    rescue => e
+      e.cause.should == e4
+    end
+  end
+
+  it "re-raises a previously rescued exception without overwriting the cause when it's explicitly specified with :cause option and has nil value" do
+    begin
+      begin
+        begin
+          begin
+            raise "Error 1"
+          rescue => e1
+            raise "Error 2"
+          end
+        rescue => e2
+          raise "Error 3"
+        end
+      rescue
+        e2.cause.should == e1
+        raise e2, cause: nil
+      end
+    rescue => e
+      e.cause.should == e1
+    end
+  end
+
+  it "re-raises a previously rescued exception without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        raise
+      end
+    rescue => e
+      e.should == e1
+      e.cause.should == nil
+    end
+  end
+
+  it "re-raises a previously rescued exception that has a cause without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          raise
+        end
+      end
+    rescue => e
+      e.should == e2
+      e.cause.should == e1
+    end
+  end
+
+  it "re-raises a previously rescued exception that doesn't have a cause and isn't a cause of any other exception with setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          raise "Error 3"
+        end
+      end
+    rescue => e
+      e.message.should == "Error 3"
+      e.cause.should == e2
+    end
+  end
+
+  it "re-raises a previously rescued exception that doesn't have a cause and is a cause of other exception without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          e1.cause.should == nil
+          e2.cause.should == e1
+          raise e1
+        end
+      end
+    rescue => e
+      e.should == e1
+      e.cause.should == nil
+    end
+  end
+
+  it "re-raises a previously rescued exception that doesn't have a cause and is a cause of other exception (that wasn't raised explicitly) without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          foo # raises NameError
+        rescue => e2
+          e1.cause.should == nil
+          e2.cause.should == e1
+          raise e1
+        end
+      end
+    rescue => e
+      e.should == e1
+      e.cause.should == nil
+    end
+  end
+
+  it "re-raises a previously rescued exception that has a cause but isn't a cause of any other exception without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          begin
+            raise "Error 3", cause: RuntimeError.new("Error 4")
+          rescue => e3
+            e2.cause.should == e1
+            e3.cause.should_not == e2
+            raise e2
+          end
+        end
+      end
+    rescue => e
+      e.should == e2
+      e.cause.should == e1
+    end
+  end
 end
 
 describe "Kernel.raise" do
-  it "needs to be reviewed for spec completeness"
+  it "is a public method" do
+    Kernel.singleton_class.should.public_method_defined?(:raise)
+  end
+
+  it_behaves_like :kernel_raise, :raise, Kernel
+  it_behaves_like :kernel_raise_with_cause, :raise, Kernel
 end
diff --git a/spec/ruby/core/kernel/rand_spec.rb b/spec/ruby/core/kernel/rand_spec.rb
index 843b5d10a2..1bf5e225d9 100644
--- a/spec/ruby/core/kernel/rand_spec.rb
+++ b/spec/ruby/core/kernel/rand_spec.rb
@@ -1,44 +1,44 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe "Kernel.rand" do
+describe "Kernel#rand" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:rand)
+    Kernel.private_instance_methods(false).should.include?(:rand)
   end
 
   it "returns a float if no argument is passed" do
-    rand.should be_kind_of(Float)
+    rand.should.is_a?(Float)
   end
 
   it "returns an integer for an integer argument" do
-    rand(77).should be_kind_of(Integer)
+    rand(77).should.is_a?(Integer)
   end
 
   it "returns an integer for a float argument greater than 1" do
-    rand(1.3).should be_kind_of(Integer)
+    rand(1.3).should.is_a?(Integer)
   end
 
   it "returns a float for an argument between -1 and 1" do
-    rand(-0.999).should be_kind_of(Float)
-    rand(-0.01).should be_kind_of(Float)
-    rand(0).should be_kind_of(Float)
-    rand(0.01).should be_kind_of(Float)
-    rand(0.999).should be_kind_of(Float)
+    rand(-0.999).should.is_a?(Float)
+    rand(-0.01).should.is_a?(Float)
+    rand(0).should.is_a?(Float)
+    rand(0.01).should.is_a?(Float)
+    rand(0.999).should.is_a?(Float)
   end
 
   it "ignores the sign of the argument" do
-    [0, 1, 2, 3].should include(rand(-4))
+    [0, 1, 2, 3].should.include?(rand(-4))
   end
 
   it "never returns a value greater or equal to 1.0 with no arguments" do
     1000.times do
-      (0...1.0).should include(rand)
+      (0...1.0).should.include?(rand)
     end
   end
 
   it "never returns a value greater or equal to any passed in max argument" do
     1000.times do
-      (0...100).to_a.should include(rand(100))
+      (0...100).to_a.should.include?(rand(100))
     end
   end
 
@@ -53,32 +53,32 @@ describe "Kernel.rand" do
     it "returns an Integer between the two Integers" do
       1000.times do
         x = rand(4...6)
-        x.should be_kind_of(Integer)
-        (4...6).should include(x)
+        x.should.is_a?(Integer)
+        (4...6).should.include?(x)
       end
     end
 
     it "returns a Float between the given Integer and Float" do
       1000.times do
         x = rand(4...6.5)
-        x.should be_kind_of(Float)
-        (4...6.5).should include(x)
+        x.should.is_a?(Float)
+        (4...6.5).should.include?(x)
       end
     end
 
     it "returns a Float between the given Float and Integer" do
       1000.times do
         x = rand(3.5...6)
-        x.should be_kind_of(Float)
-        (3.5...6).should include(x)
+        x.should.is_a?(Float)
+        (3.5...6).should.include?(x)
       end
     end
 
     it "returns a Float between the two given Floats" do
       1000.times do
         x = rand(3.5...6.5)
-        x.should be_kind_of(Float)
-        (3.5...6.5).should include(x)
+        x.should.is_a?(Float)
+        (3.5...6.5).should.include?(x)
       end
     end
   end
@@ -87,59 +87,111 @@ describe "Kernel.rand" do
     it "returns an Integer between the two Integers" do
       1000.times do
         x = rand(4..6)
-        x.should be_kind_of(Integer)
-        (4..6).should include(x)
+        x.should.is_a?(Integer)
+        (4..6).should.include?(x)
       end
     end
 
     it "returns a Float between the given Integer and Float" do
       1000.times do
         x = rand(4..6.5)
-        x.should be_kind_of(Float)
-        (4..6.5).should include(x)
+        x.should.is_a?(Float)
+        (4..6.5).should.include?(x)
       end
     end
 
     it "returns a Float between the given Float and Integer" do
       1000.times do
         x = rand(3.5..6)
-        x.should be_kind_of(Float)
-        (3.5..6).should include(x)
+        x.should.is_a?(Float)
+        (3.5..6).should.include?(x)
       end
     end
 
     it "returns a Float between the two given Floats" do
       1000.times do
         x = rand(3.5..6.5)
-        x.should be_kind_of(Float)
-        (3.5..6.5).should include(x)
+        x.should.is_a?(Float)
+        (3.5..6.5).should.include?(x)
       end
     end
   end
 
+  context "given an inclusive range between 0 and 1" do
+    it "returns an Integer between the two Integers" do
+      x = rand(0..1)
+      x.should.is_a?(Integer)
+      (0..1).should.include?(x)
+    end
+
+    it "returns a Float if at least one side is Float" do
+      seed = 42
+      x1 = Random.new(seed).rand(0..1.0)
+      x2 = Random.new(seed).rand(0.0..1.0)
+      x3 = Random.new(seed).rand(0.0..1)
+
+      x3.should.is_a?(Float)
+      x1.should.eql?(x3)
+      x2.should.eql?(x3)
+
+      (0.0..1.0).should.include?(x3)
+    end
+  end
+
+  context "given an exclusive range between 0 and 1" do
+    it "returns zero as an Integer" do
+      x = rand(0...1)
+      x.should.is_a?(Integer)
+      x.should.eql?(0)
+    end
+
+    it "returns a Float if at least one side is Float" do
+      seed = 42
+      x1 = Random.new(seed).rand(0...1.0)
+      x2 = Random.new(seed).rand(0.0...1.0)
+      x3 = Random.new(seed).rand(0.0...1)
+
+      x3.should.is_a?(Float)
+      x1.should.eql?(x3)
+      x2.should.eql?(x3)
+
+      (0.0...1.0).should.include?(x3)
+    end
+  end
+
   it "returns a numeric for an range argument where max is < 1" do
-    rand(0.25..0.75).should be_kind_of(Numeric)
+    rand(0.25..0.75).should.is_a?(Numeric)
   end
 
   it "returns nil when range is backwards" do
-    rand(1..0).should be_nil
+    rand(1..0).should == nil
   end
 
   it "returns the range start/end when Float range is 0" do
-    rand(1.0..1.0).should eql(1.0)
+    rand(1.0..1.0).should.eql?(1.0)
   end
 
   it "returns the range start/end when Integer range is 0" do
-    rand(42..42).should eql(42)
+    rand(42..42).should.eql?(42)
   end
 
   it "supports custom object types" do
-    rand(KernelSpecs::CustomRangeInteger.new(1)..KernelSpecs::CustomRangeInteger.new(42)).should be_an_instance_of(KernelSpecs::CustomRangeInteger)
-    rand(KernelSpecs::CustomRangeFloat.new(1.0)..KernelSpecs::CustomRangeFloat.new(42.0)).should be_an_instance_of(KernelSpecs::CustomRangeFloat)
-    rand(Time.now..Time.now).should be_an_instance_of(Time)
+    rand(KernelSpecs::CustomRangeInteger.new(1)..KernelSpecs::CustomRangeInteger.new(42)).should.instance_of?(KernelSpecs::CustomRangeInteger)
+    rand(KernelSpecs::CustomRangeFloat.new(1.0)..KernelSpecs::CustomRangeFloat.new(42.0)).should.instance_of?(KernelSpecs::CustomRangeFloat)
+    rand(Time.now..Time.now).should.instance_of?(Time)
+  end
+
+  it "is random on boot" do
+    results = 2.times.map {
+      out = ruby_exe('p rand', options: '--disable-gems')
+      Float(out)
+    }
+    results.size.should == 2
+    # this is technically flaky, but very unlikely in a good distribution
+    results[0].should_not == results[1]
   end
 end
 
-describe "Kernel#rand" do
+describe "Kernel.rand" do
   it "needs to be reviewed for spec completeness"
 end
diff --git a/spec/ruby/core/kernel/readline_spec.rb b/spec/ruby/core/kernel/readline_spec.rb
index dce7b03dc8..86899d78d2 100644
--- a/spec/ruby/core/kernel/readline_spec.rb
+++ b/spec/ruby/core/kernel/readline_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#readline" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:readline)
+    Kernel.private_instance_methods(false).should.include?(:readline)
   end
 end
 
diff --git a/spec/ruby/core/kernel/readlines_spec.rb b/spec/ruby/core/kernel/readlines_spec.rb
index 2b6d65fff2..c758014aab 100644
--- a/spec/ruby/core/kernel/readlines_spec.rb
+++ b/spec/ruby/core/kernel/readlines_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#readlines" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:readlines)
+    Kernel.private_instance_methods(false).should.include?(:readlines)
   end
 end
 
diff --git a/spec/ruby/core/kernel/remove_instance_variable_spec.rb b/spec/ruby/core/kernel/remove_instance_variable_spec.rb
index e90efc8aed..114536064f 100644
--- a/spec/ruby/core/kernel/remove_instance_variable_spec.rb
+++ b/spec/ruby/core/kernel/remove_instance_variable_spec.rb
@@ -9,7 +9,7 @@ describe :kernel_remove_instance_variable, shared: true do
 
   it "removes the instance variable" do
     @instance.send :remove_instance_variable, @object
-    @instance.instance_variable_defined?(@object).should be_false
+    @instance.instance_variable_defined?(@object).should == false
   end
 end
 
@@ -19,26 +19,39 @@ describe "Kernel#remove_instance_variable" do
   end
 
   it "is a public method" do
-    Kernel.should have_public_instance_method(:remove_instance_variable, false)
+    Kernel.public_instance_methods(false).should.include?(:remove_instance_variable)
   end
 
   it "raises a NameError if the instance variable is not defined" do
     -> do
       @instance.send :remove_instance_variable, :@unknown
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the argument is not a valid instance variable name" do
     -> do
       @instance.send :remove_instance_variable, :"@0"
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a TypeError if passed an Object not defining #to_str" do
     -> do
       obj = mock("kernel remove_instance_variable")
       @instance.send :remove_instance_variable, obj
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
+  end
+
+  it "raises a FrozenError if self is frozen" do
+    o = Object.new
+    o.freeze
+    -> { o.remove_instance_variable(:@foo) }.should.raise(FrozenError)
+    -> { o.remove_instance_variable(:foo) }.should.raise(NameError)
+  end
+
+  it "raises for frozen objects" do
+    -> { nil.remove_instance_variable(:@foo) }.should.raise(FrozenError)
+    -> { nil.remove_instance_variable(:foo) }.should.raise(NameError)
+    -> { :foo.remove_instance_variable(:@foo) }.should.raise(FrozenError)
   end
 
   describe "when passed a String" do
diff --git a/spec/ruby/core/kernel/require_relative_spec.rb b/spec/ruby/core/kernel/require_relative_spec.rb
index b292a46c63..332045b200 100644
--- a/spec/ruby/core/kernel/require_relative_spec.rb
+++ b/spec/ruby/core/kernel/require_relative_spec.rb
@@ -5,9 +5,9 @@ describe "Kernel#require_relative with a relative path" do
   before :each do
     CodeLoadingSpecs.spec_setup
     @dir = "../../fixtures/code"
-    @abs_dir = File.realpath(@dir, File.dirname(__FILE__))
+    @abs_dir = File.realpath(@dir, __dir__)
     @path = "#{@dir}/load_fixture.rb"
-    @abs_path = File.realpath(@path, File.dirname(__FILE__))
+    @abs_path = File.realpath(@path, __dir__)
   end
 
   after :each do
@@ -27,14 +27,14 @@ describe "Kernel#require_relative with a relative path" do
       end
 
       it "loads a path relative to current file" do
-        require_relative(@link).should be_true
+        require_relative(@link).should == true
         ScratchPad.recorded.should == [:loaded]
       end
     end
   end
 
   it "loads a path relative to the current file" do
-    require_relative(@path).should be_true
+    require_relative(@path).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
@@ -42,14 +42,14 @@ describe "Kernel#require_relative with a relative path" do
 
     it "synthetic file base name loads a file base name relative to the working directory" do
       Dir.chdir @abs_dir do
-        Object.new.instance_eval("require_relative(#{File.basename(@path).inspect})", "foo.rb").should be_true
+        Object.new.instance_eval("require_relative(#{File.basename(@path).inspect})", "foo.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "synthetic file path loads a relative path relative to the working directory plus the directory of the synthetic path" do
       Dir.chdir @abs_dir do
-        Object.new.instance_eval("require_relative(File.join('..', #{File.basename(@path).inspect}))", "bar/foo.rb").should be_true
+        Object.new.instance_eval("require_relative(File.join('..', #{File.basename(@path).inspect}))", "bar/foo.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -57,14 +57,14 @@ describe "Kernel#require_relative with a relative path" do
     platform_is_not :windows do
       it "synthetic relative file path with a Windows path separator specified loads a relative path relative to the working directory" do
         Dir.chdir @abs_dir do
-          Object.new.instance_eval("require_relative(#{File.basename(@path).inspect})", "bar\\foo.rb").should be_true
+          Object.new.instance_eval("require_relative(#{File.basename(@path).inspect})", "bar\\foo.rb").should == true
         end
         ScratchPad.recorded.should == [:loaded]
       end
     end
 
     it "absolute file path loads a path relative to the absolute path" do
-      Object.new.instance_eval("require_relative(#{@path.inspect})", __FILE__).should be_true
+      Object.new.instance_eval("require_relative(#{@path.inspect})", __FILE__).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -74,24 +74,34 @@ describe "Kernel#require_relative with a relative path" do
         root = File.dirname(root)
       end
       root_relative = @abs_path[root.size..-1]
-      Object.new.instance_eval("require_relative(#{root_relative.inspect})", "/").should be_true
+      Object.new.instance_eval("require_relative(#{root_relative.inspect})", "/").should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
   end
 
   it "loads a file defining many methods" do
-    require_relative("#{@dir}/methods_fixture.rb").should be_true
+    require_relative("#{@dir}/methods_fixture.rb").should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "raises a LoadError if the file does not exist" do
-    -> { require_relative("#{@dir}/nonexistent.rb") }.should raise_error(LoadError)
+    -> { require_relative("#{@dir}/nonexistent.rb") }.should.raise(LoadError)
+    ScratchPad.recorded.should == []
+  end
+
+  it "raises a LoadError that includes the missing path" do
+    missing_path = "#{@dir}/nonexistent.rb"
+    expanded_missing_path = File.expand_path(missing_path, __dir__)
+    -> { require_relative(missing_path) }.should.raise(LoadError) { |e|
+      e.message.should.include?(expanded_missing_path)
+      e.path.should == expanded_missing_path
+    }
     ScratchPad.recorded.should == []
   end
 
   it "raises a LoadError if basepath does not exist" do
-    -> { eval("require_relative('#{@dir}/nonexistent.rb')") }.should raise_error(LoadError)
+    -> { eval("require_relative('#{@dir}/nonexistent.rb')") }.should.raise(LoadError)
   end
 
   it "stores the missing path in a LoadError object" do
@@ -107,34 +117,34 @@ describe "Kernel#require_relative with a relative path" do
   it "calls #to_str on non-String objects" do
     name = mock("load_fixture.rb mock")
     name.should_receive(:to_str).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "raises a TypeError if argument does not respond to #to_str" do
-    -> { require_relative(nil) }.should raise_error(TypeError)
-    -> { require_relative(42) }.should raise_error(TypeError)
+    -> { require_relative(nil) }.should.raise(TypeError)
+    -> { require_relative(42) }.should.raise(TypeError)
     -> {
       require_relative([@path,@path])
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that has #to_s but not #to_str" do
     name = mock("load_fixture.rb mock")
     name.stub!(:to_s).and_return(@path)
-    -> { require_relative(name) }.should raise_error(TypeError)
+    -> { require_relative(name) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_str does not return a String" do
     name = mock("#to_str returns nil")
     name.should_receive(:to_str).at_least(1).times.and_return(nil)
-    -> { require_relative(name) }.should raise_error(TypeError)
+    -> { require_relative(name) }.should.raise(TypeError)
   end
 
   it "calls #to_path on non-String objects" do
     name = mock("load_fixture.rb mock")
     name.should_receive(:to_path).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
@@ -143,13 +153,13 @@ describe "Kernel#require_relative with a relative path" do
     to_path = mock("load_fixture_rb #to_path mock")
     name.should_receive(:to_path).and_return(to_path)
     to_path.should_receive(:to_str).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   describe "(file extensions)" do
     it "loads a .rb extensioned file when passed a non-extensioned path" do
-      require_relative("#{@dir}/load_fixture").should be_true
+      require_relative("#{@dir}/load_fixture").should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -158,20 +168,20 @@ describe "Kernel#require_relative with a relative path" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.dylib"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.so"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.dll"
-      require_relative(@path).should be_true
+      require_relative(@path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "does not load a C-extension file if a .rb extensioned file is already loaded" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.rb"
-      require_relative("#{@dir}/load_fixture").should be_false
+      require_relative("#{@dir}/load_fixture").should == false
       ScratchPad.recorded.should == []
     end
 
     it "loads a .rb extensioned file when passed a non-.rb extensioned path" do
-      require_relative("#{@dir}/load_fixture.ext").should be_true
+      require_relative("#{@dir}/load_fixture.ext").should == true
       ScratchPad.recorded.should == [:loaded]
-      $LOADED_FEATURES.should include "#{@abs_dir}/load_fixture.ext.rb"
+      $LOADED_FEATURES.should.include? "#{@abs_dir}/load_fixture.ext.rb"
     end
 
     it "loads a .rb extensioned file when a complex-extensioned C-extension file of the same name is loaded" do
@@ -179,25 +189,25 @@ describe "Kernel#require_relative with a relative path" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.dylib"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.so"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.dll"
-      require_relative("#{@dir}/load_fixture.ext").should be_true
+      require_relative("#{@dir}/load_fixture.ext").should == true
       ScratchPad.recorded.should == [:loaded]
-      $LOADED_FEATURES.should include "#{@abs_dir}/load_fixture.ext.rb"
+      $LOADED_FEATURES.should.include? "#{@abs_dir}/load_fixture.ext.rb"
     end
 
     it "does not load a C-extension file if a complex-extensioned .rb file is already loaded" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.rb"
-      require_relative("#{@dir}/load_fixture.ext").should be_false
+      require_relative("#{@dir}/load_fixture.ext").should == false
       ScratchPad.recorded.should == []
     end
   end
 
   describe "($LOADED_FEATURES)" do
     it "stores an absolute path" do
-      require_relative(@path).should be_true
-      $LOADED_FEATURES.should include(@abs_path)
+      require_relative(@path).should == true
+      $LOADED_FEATURES.should.include?(@abs_path)
     end
 
-    platform_is_not :windows do
+    platform_is_not :windows, :wasi do
       describe "with symlinks" do
         before :each do
           @symlink_to_code_dir = tmp("codesymlink")
@@ -221,8 +231,8 @@ describe "Kernel#require_relative with a relative path" do
           ScratchPad.recorded.should == [:loaded]
 
           features = $LOADED_FEATURES.select { |path| path.end_with?('load_fixture.rb') }
-          features.should include(absolute_path)
-          features.should_not include(canonical_path)
+          features.should.include?(absolute_path)
+          features.should_not.include?(canonical_path)
         end
 
         it "stores the same path that __FILE__ returns in the required file" do
@@ -239,26 +249,26 @@ describe "Kernel#require_relative with a relative path" do
 
     it "does not store the path if the load fails" do
       saved_loaded_features = $LOADED_FEATURES.dup
-      -> { require_relative("#{@dir}/raise_fixture.rb") }.should raise_error(RuntimeError)
+      -> { require_relative("#{@dir}/raise_fixture.rb") }.should.raise(RuntimeError)
       $LOADED_FEATURES.should == saved_loaded_features
     end
 
     it "does not load an absolute path that is already stored" do
       $LOADED_FEATURES << @abs_path
-      require_relative(@path).should be_false
+      require_relative(@path).should == false
       ScratchPad.recorded.should == []
     end
 
     it "adds the suffix of the resolved filename" do
-      require_relative("#{@dir}/load_fixture").should be_true
-      $LOADED_FEATURES.should include("#{@abs_dir}/load_fixture.rb")
+      require_relative("#{@dir}/load_fixture").should == true
+      $LOADED_FEATURES.should.include?("#{@abs_dir}/load_fixture.rb")
     end
 
     it "loads a path for a file already loaded with a relative path" do
       $LOAD_PATH << File.expand_path(@dir)
       $LOADED_FEATURES << "load_fixture.rb" << "load_fixture"
-      require_relative(@path).should be_true
-      $LOADED_FEATURES.should include(@abs_path)
+      require_relative(@path).should == true
+      $LOADED_FEATURES.should.include?(@abs_path)
       ScratchPad.recorded.should == [:loaded]
     end
   end
@@ -267,7 +277,7 @@ end
 describe "Kernel#require_relative with an absolute path" do
   before :each do
     CodeLoadingSpecs.spec_setup
-    @dir = File.expand_path "../../fixtures/code", File.dirname(__FILE__)
+    @dir = File.expand_path "../../fixtures/code", __dir__
     @abs_dir = @dir
     @path = File.join @dir, "load_fixture.rb"
     @abs_path = @path
@@ -278,22 +288,22 @@ describe "Kernel#require_relative with an absolute path" do
   end
 
   it "loads a path relative to the current file" do
-    require_relative(@path).should be_true
+    require_relative(@path).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "loads a file defining many methods" do
-    require_relative("#{@dir}/methods_fixture.rb").should be_true
+    require_relative("#{@dir}/methods_fixture.rb").should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "raises a LoadError if the file does not exist" do
-    -> { require_relative("#{@dir}/nonexistent.rb") }.should raise_error(LoadError)
+    -> { require_relative("#{@dir}/nonexistent.rb") }.should.raise(LoadError)
     ScratchPad.recorded.should == []
   end
 
   it "raises a LoadError if basepath does not exist" do
-    -> { eval("require_relative('#{@dir}/nonexistent.rb')") }.should raise_error(LoadError)
+    -> { eval("require_relative('#{@dir}/nonexistent.rb')") }.should.raise(LoadError)
   end
 
   it "stores the missing path in a LoadError object" do
@@ -309,34 +319,34 @@ describe "Kernel#require_relative with an absolute path" do
   it "calls #to_str on non-String objects" do
     name = mock("load_fixture.rb mock")
     name.should_receive(:to_str).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "raises a TypeError if argument does not respond to #to_str" do
-    -> { require_relative(nil) }.should raise_error(TypeError)
-    -> { require_relative(42) }.should raise_error(TypeError)
+    -> { require_relative(nil) }.should.raise(TypeError)
+    -> { require_relative(42) }.should.raise(TypeError)
     -> {
       require_relative([@path,@path])
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that has #to_s but not #to_str" do
     name = mock("load_fixture.rb mock")
     name.stub!(:to_s).and_return(@path)
-    -> { require_relative(name) }.should raise_error(TypeError)
+    -> { require_relative(name) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_str does not return a String" do
     name = mock("#to_str returns nil")
     name.should_receive(:to_str).at_least(1).times.and_return(nil)
-    -> { require_relative(name) }.should raise_error(TypeError)
+    -> { require_relative(name) }.should.raise(TypeError)
   end
 
   it "calls #to_path on non-String objects" do
     name = mock("load_fixture.rb mock")
     name.should_receive(:to_path).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
@@ -345,13 +355,13 @@ describe "Kernel#require_relative with an absolute path" do
     to_path = mock("load_fixture_rb #to_path mock")
     name.should_receive(:to_path).and_return(to_path)
     to_path.should_receive(:to_str).and_return(@path)
-    require_relative(name).should be_true
+    require_relative(name).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   describe "(file extensions)" do
     it "loads a .rb extensioned file when passed a non-extensioned path" do
-      require_relative("#{@dir}/load_fixture").should be_true
+      require_relative("#{@dir}/load_fixture").should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -360,20 +370,20 @@ describe "Kernel#require_relative with an absolute path" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.dylib"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.so"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.dll"
-      require_relative(@path).should be_true
+      require_relative(@path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "does not load a C-extension file if a .rb extensioned file is already loaded" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.rb"
-      require_relative("#{@dir}/load_fixture").should be_false
+      require_relative("#{@dir}/load_fixture").should == false
       ScratchPad.recorded.should == []
     end
 
     it "loads a .rb extensioned file when passed a non-.rb extensioned path" do
-      require_relative("#{@dir}/load_fixture.ext").should be_true
+      require_relative("#{@dir}/load_fixture.ext").should == true
       ScratchPad.recorded.should == [:loaded]
-      $LOADED_FEATURES.should include "#{@abs_dir}/load_fixture.ext.rb"
+      $LOADED_FEATURES.should.include? "#{@abs_dir}/load_fixture.ext.rb"
     end
 
     it "loads a .rb extensioned file when a complex-extensioned C-extension file of the same name is loaded" do
@@ -381,46 +391,46 @@ describe "Kernel#require_relative with an absolute path" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.dylib"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.so"
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.dll"
-      require_relative("#{@dir}/load_fixture.ext").should be_true
+      require_relative("#{@dir}/load_fixture.ext").should == true
       ScratchPad.recorded.should == [:loaded]
-      $LOADED_FEATURES.should include "#{@abs_dir}/load_fixture.ext.rb"
+      $LOADED_FEATURES.should.include? "#{@abs_dir}/load_fixture.ext.rb"
     end
 
     it "does not load a C-extension file if a complex-extensioned .rb file is already loaded" do
       $LOADED_FEATURES << "#{@abs_dir}/load_fixture.ext.rb"
-      require_relative("#{@dir}/load_fixture.ext").should be_false
+      require_relative("#{@dir}/load_fixture.ext").should == false
       ScratchPad.recorded.should == []
     end
   end
 
   describe "($LOAD_FEATURES)" do
     it "stores an absolute path" do
-      require_relative(@path).should be_true
-      $LOADED_FEATURES.should include(@abs_path)
+      require_relative(@path).should == true
+      $LOADED_FEATURES.should.include?(@abs_path)
     end
 
     it "does not store the path if the load fails" do
       saved_loaded_features = $LOADED_FEATURES.dup
-      -> { require_relative("#{@dir}/raise_fixture.rb") }.should raise_error(RuntimeError)
+      -> { require_relative("#{@dir}/raise_fixture.rb") }.should.raise(RuntimeError)
       $LOADED_FEATURES.should == saved_loaded_features
     end
 
     it "does not load an absolute path that is already stored" do
       $LOADED_FEATURES << @abs_path
-      require_relative(@path).should be_false
+      require_relative(@path).should == false
       ScratchPad.recorded.should == []
     end
 
     it "adds the suffix of the resolved filename" do
-      require_relative("#{@dir}/load_fixture").should be_true
-      $LOADED_FEATURES.should include("#{@abs_dir}/load_fixture.rb")
+      require_relative("#{@dir}/load_fixture").should == true
+      $LOADED_FEATURES.should.include?("#{@abs_dir}/load_fixture.rb")
     end
 
     it "loads a path for a file already loaded with a relative path" do
       $LOAD_PATH << File.expand_path(@dir)
       $LOADED_FEATURES << "load_fixture.rb" << "load_fixture"
-      require_relative(@path).should be_true
-      $LOADED_FEATURES.should include(@abs_path)
+      require_relative(@path).should == true
+      $LOADED_FEATURES.should.include?(@abs_path)
       ScratchPad.recorded.should == [:loaded]
     end
   end
diff --git a/spec/ruby/core/kernel/require_spec.rb b/spec/ruby/core/kernel/require_spec.rb
index dc3da4b7e6..62d954c2bf 100644
--- a/spec/ruby/core/kernel/require_spec.rb
+++ b/spec/ruby/core/kernel/require_spec.rb
@@ -13,7 +13,40 @@ describe "Kernel#require" do
 
   # if this fails, update your rubygems
   it "is a private method" do
-    Kernel.should have_private_instance_method(:require)
+    Kernel.private_instance_methods(false).should.include?(:require)
+  end
+
+  it "provided features are already required" do
+    provided = %w[complex enumerator fiber rational thread ruby2_keywords]
+    ruby_version_is "4.0" do
+      provided += %w[set pathname]
+    end
+    ruby_version_is "4.1" do
+      provided += %w[monitor]
+    end
+
+    out = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems --disable-did-you-mean')
+    features = out.lines.map(&:chomp)
+
+    # Ignore engine-specific internals
+    case RUBY_ENGINE
+    when "jruby"
+      features -= %w[java.rb jruby/util.rb]
+    when "ruby"
+      so = RbConfig::CONFIG['DLEXT']
+      features -= ["windows_1252.#{so}", "windows_31.#{so}"]
+      features.reject! { |feature| feature.end_with? "encdb.#{so}" }
+      features.reject! { |feature| feature.end_with? "transdb.#{so}" }
+      features.reject! { |feature| feature.include?('-fake') }
+    end
+
+    features_no_ext = features.map { |path| File.basename(path, '.*') }
+    features_no_ext.sort.should == provided.sort
+
+    requires = features
+    code = requires.map { |f| "puts require #{f.inspect}\n" }.join
+    required = ruby_exe(code, options: '--disable-gems')
+    required.should == "false\n" * requires.size
   end
 
   it_behaves_like :kernel_require_basic, :require, CodeLoadingSpecs::Method.new
diff --git a/spec/ruby/core/kernel/respond_to_missing_spec.rb b/spec/ruby/core/kernel/respond_to_missing_spec.rb
index cc82031e26..08c9184fb4 100644
--- a/spec/ruby/core/kernel/respond_to_missing_spec.rb
+++ b/spec/ruby/core/kernel/respond_to_missing_spec.rb
@@ -7,7 +7,7 @@ describe "Kernel#respond_to_missing?" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:respond_to_missing?, false)
+    Kernel.private_instance_methods(false).should.include?(:respond_to_missing?)
   end
 
   it "is only an instance method" do
@@ -18,7 +18,7 @@ describe "Kernel#respond_to_missing?" do
     obj = mock('object')
     obj.stub!(:glark)
     obj.should_not_receive(:respond_to_missing?)
-    obj.respond_to?(:glark).should be_true
+    obj.respond_to?(:glark).should == true
   end
 
   it "is called with a 2nd argument of false when #respond_to? is" do
@@ -48,39 +48,39 @@ describe "Kernel#respond_to_missing?" do
   it "causes #respond_to? to return true if called and not returning false" do
     obj = mock('object')
     obj.should_receive(:respond_to_missing?).with(:undefined_method, false).and_return(:glark)
-    obj.respond_to?(:undefined_method).should be_true
+    obj.respond_to?(:undefined_method).should == true
   end
 
   it "causes #respond_to? to return false if called and returning false" do
     obj = mock('object')
     obj.should_receive(:respond_to_missing?).with(:undefined_method, false).and_return(false)
-    obj.respond_to?(:undefined_method).should be_false
+    obj.respond_to?(:undefined_method).should == false
   end
 
   it "causes #respond_to? to return false if called and returning nil" do
     obj = mock('object')
     obj.should_receive(:respond_to_missing?).with(:undefined_method, false).and_return(nil)
-    obj.respond_to?(:undefined_method).should be_false
+    obj.respond_to?(:undefined_method).should == false
   end
 
   it "isn't called when obj responds to the given public method" do
     @a.should_not_receive(:respond_to_missing?)
-    @a.respond_to?(:pub_method).should be_true
+    @a.respond_to?(:pub_method).should == true
   end
 
   it "isn't called when obj responds to the given public method, include_private = true" do
     @a.should_not_receive(:respond_to_missing?)
-    @a.respond_to?(:pub_method, true).should be_true
+    @a.respond_to?(:pub_method, true).should == true
   end
 
   it "is called when obj responds to the given protected method, include_private = false" do
     @a.should_receive(:respond_to_missing?)
-    @a.respond_to?(:protected_method, false).should be_false
+    @a.respond_to?(:protected_method, false).should == false
   end
 
   it "isn't called when obj responds to the given protected method, include_private = true" do
     @a.should_not_receive(:respond_to_missing?)
-    @a.respond_to?(:protected_method, true).should be_true
+    @a.respond_to?(:protected_method, true).should == true
   end
 
   it "is called when obj responds to the given private method, include_private = false" do
@@ -90,7 +90,7 @@ describe "Kernel#respond_to_missing?" do
 
   it "isn't called when obj responds to the given private method, include_private = true" do
     @a.should_not_receive(:respond_to_missing?)
-    @a.respond_to?(:private_method, true).should be_true
+    @a.respond_to?(:private_method, true).should == true
   end
 
   it "is called for missing class methods" do
diff --git a/spec/ruby/core/kernel/respond_to_spec.rb b/spec/ruby/core/kernel/respond_to_spec.rb
index e7efc9f275..72ab4eebe1 100644
--- a/spec/ruby/core/kernel/respond_to_spec.rb
+++ b/spec/ruby/core/kernel/respond_to_spec.rb
@@ -7,7 +7,7 @@ describe "Kernel#respond_to?" do
   end
 
   it "is a public method" do
-    Kernel.should have_public_instance_method(:respond_to?, false)
+    Kernel.public_instance_methods(false).should.include?(:respond_to?)
   end
 
   it "is only an instance method" do
@@ -25,7 +25,7 @@ describe "Kernel#respond_to?" do
   end
 
   it "throws a type error if argument can't be coerced into a Symbol" do
-    -> { @a.respond_to?(Object.new) }.should raise_error(TypeError)
+    -> { @a.respond_to?(Object.new) }.should.raise(TypeError, /is not a symbol nor a string/)
   end
 
   it "returns false if obj responds to the given protected method" do
@@ -61,7 +61,7 @@ describe "Kernel#respond_to?" do
   it "does not change method visibility when finding private method" do
     KernelSpecs::VisibilityChange.respond_to?(:new, false).should == false
     KernelSpecs::VisibilityChange.respond_to?(:new, true).should == true
-    -> { KernelSpecs::VisibilityChange.new }.should raise_error(NoMethodError)
+    -> { KernelSpecs::VisibilityChange.new }.should.raise(NoMethodError)
   end
 
   it "indicates if an object responds to a particular message" do
@@ -70,4 +70,30 @@ describe "Kernel#respond_to?" do
     KernelSpecs::Foo.new.respond_to?(:invalid_and_silly_method_name).should == false
   end
 
+  context "if object does not have #respond_to_missing?" do
+    it "returns true if object responds to the given public method" do
+      KernelSpecs::BasicA.new.respond_to?(:pub_method).should == true
+      KernelSpecs::MissingA.new.respond_to?(:pub_method).should == true
+    end
+
+    it "returns false if object responds to the given protected method" do
+      KernelSpecs::BasicA.new.respond_to?(:protected_method).should == false
+      KernelSpecs::MissingA.new.respond_to?(:protected_method).should == false
+    end
+
+    it "returns false if object responds to the given private method" do
+      KernelSpecs::BasicA.new.respond_to?(:private_method).should == false
+      KernelSpecs::MissingA.new.respond_to?(:private_method).should == false
+    end
+
+    it "returns false if the given method was undefined" do
+      KernelSpecs::BasicA.new.respond_to?(:undefed_method).should == false
+      KernelSpecs::MissingA.new.respond_to?(:undefed_method).should == false
+    end
+
+    it "returns false if the given method never existed" do
+      KernelSpecs::BasicA.new.respond_to?(:invalid_and_silly_method_name).should == false
+      KernelSpecs::MissingA.new.respond_to?(:invalid_and_silly_method_name).should == false
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/select_spec.rb b/spec/ruby/core/kernel/select_spec.rb
index e0d82f3079..58c963c1a4 100644
--- a/spec/ruby/core/kernel/select_spec.rb
+++ b/spec/ruby/core/kernel/select_spec.rb
@@ -3,16 +3,16 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#select" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:select)
+    Kernel.private_instance_methods(false).should.include?(:select)
   end
 end
 
 describe "Kernel.select" do
   it 'does not block when timeout is 0' do
     IO.pipe do |read, write|
-      IO.select([read], [], [], 0).should == nil
+      select([read], [], [], 0).should == nil
       write.write 'data'
-      IO.select([read], [], [], 0).should == [[read], [], []]
+      select([read], [], [], 0).should == [[read], [], []]
     end
   end
 end
diff --git a/spec/ruby/core/kernel/set_trace_func_spec.rb b/spec/ruby/core/kernel/set_trace_func_spec.rb
index 1f43e7a009..5201812f2f 100644
--- a/spec/ruby/core/kernel/set_trace_func_spec.rb
+++ b/spec/ruby/core/kernel/set_trace_func_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#set_trace_func" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:set_trace_func)
+    Kernel.private_instance_methods(false).should.include?(:set_trace_func)
   end
 end
 
diff --git a/spec/ruby/core/kernel/shared/dup_clone.rb b/spec/ruby/core/kernel/shared/dup_clone.rb
index d1ee64bd09..3fbf918283 100644
--- a/spec/ruby/core/kernel/shared/dup_clone.rb
+++ b/spec/ruby/core/kernel/shared/dup_clone.rb
@@ -40,7 +40,7 @@ describe :kernel_dup_clone, shared: true do
     o.obj = array
 
     o2 = o.send(@method)
-    o2.obj.should equal(o.obj)
+    o2.obj.should.equal?(o.obj)
   end
 
   it "calls #initialize_copy on the NEW object if available, passing in original object" do
@@ -49,17 +49,7 @@ describe :kernel_dup_clone, shared: true do
 
     o.obj.should == :original
     o2.obj.should == :init_copy
-    o2.original.should equal(o)
-  end
-
-  it "preserves tainted state from the original" do
-    o = ObjectSpecDupInitCopy.new
-    o2 = o.send(@method)
-    o.taint
-    o3 = o.send(@method)
-
-    o2.tainted?.should == false
-    o3.tainted?.should == true
+    o2.original.should.equal?(o)
   end
 
   it "does not preserve the object_id" do
@@ -69,16 +59,6 @@ describe :kernel_dup_clone, shared: true do
     o2.object_id.should_not == old_object_id
   end
 
-  it "preserves untrusted state from the original" do
-    o = ObjectSpecDupInitCopy.new
-    o2 = o.send(@method)
-    o.untrust
-    o3 = o.send(@method)
-
-    o2.untrusted?.should == false
-    o3.untrusted?.should == true
-  end
-
   it "returns nil for NilClass" do
     nil.send(@method).should == nil
   end
@@ -99,27 +79,13 @@ describe :kernel_dup_clone, shared: true do
     :my_symbol.send(@method).should == :my_symbol
   end
 
-  ruby_version_is ''...'2.5' do
-    it "raises a TypeError for Complex" do
-      c = Complex(1.3, 3.1)
-      -> { c.send(@method) }.should raise_error(TypeError)
-    end
-
-    it "raises a TypeError for Rational" do
-      r = Rational(1, 3)
-      -> { r.send(@method) }.should raise_error(TypeError)
-    end
+  it "returns self for Complex" do
+    c = Complex(1.3, 3.1)
+    c.send(@method).should.equal? c
   end
 
-  ruby_version_is '2.5' do
-    it "returns self for Complex" do
-      c = Complex(1.3, 3.1)
-      c.send(@method).should equal c
-    end
-
-    it "returns self for Rational" do
-      r = Rational(1, 3)
-      r.send(@method).should equal r
-    end
+  it "returns self for Rational" do
+    r = Rational(1, 3)
+    r.send(@method).should.equal? r
   end
 end
diff --git a/spec/ruby/core/kernel/shared/kind_of.rb b/spec/ruby/core/kernel/shared/kind_of.rb
index aef6f1c1d8..a5e0eab08f 100644
--- a/spec/ruby/core/kernel/shared/kind_of.rb
+++ b/spec/ruby/core/kernel/shared/kind_of.rb
@@ -40,10 +40,10 @@ describe :kernel_kind_of, shared: true do
   end
 
   it "raises a TypeError if given an object that is not a Class nor a Module" do
-    -> { @o.send(@method, 1) }.should raise_error(TypeError)
-    -> { @o.send(@method, 'KindaClass') }.should raise_error(TypeError)
-    -> { @o.send(@method, :KindaClass) }.should raise_error(TypeError)
-    -> { @o.send(@method, Object.new) }.should raise_error(TypeError)
+    -> { @o.send(@method, 1) }.should.raise(TypeError)
+    -> { @o.send(@method, 'KindaClass') }.should.raise(TypeError)
+    -> { @o.send(@method, :KindaClass) }.should.raise(TypeError)
+    -> { @o.send(@method, Object.new) }.should.raise(TypeError)
   end
 
   it "does not take into account `class` method overriding" do
diff --git a/spec/ruby/core/kernel/shared/lambda.rb b/spec/ruby/core/kernel/shared/lambda.rb
index c7180e1442..83de06bb41 100644
--- a/spec/ruby/core/kernel/shared/lambda.rb
+++ b/spec/ruby/core/kernel/shared/lambda.rb
@@ -4,6 +4,8 @@ describe :kernel_lambda, shared: true do
   end
 
   it "raises an ArgumentError when no block is given" do
-    -> { send(@method) }.should raise_error(ArgumentError)
+    suppress_warning do
+      -> { send(@method) }.should.raise(ArgumentError)
+    end
   end
 end
diff --git a/spec/ruby/core/kernel/shared/load.rb b/spec/ruby/core/kernel/shared/load.rb
index 14bf5f27da..20d23a623e 100644
--- a/spec/ruby/core/kernel/shared/load.rb
+++ b/spec/ruby/core/kernel/shared/load.rb
@@ -1,3 +1,6 @@
+main = self
+
+# The big difference is Kernel#load does not attempt to add an extension to the passed path, unlike Kernel#require
 describe :kernel_load, shared: true do
   before :each do
     CodeLoadingSpecs.spec_setup
@@ -8,100 +11,141 @@ describe :kernel_load, shared: true do
     CodeLoadingSpecs.spec_cleanup
   end
 
-  it "loads a non-extensioned file as a Ruby source file" do
-    path = File.expand_path "load_fixture", CODE_LOADING_DIR
-    @object.load(path).should be_true
-    ScratchPad.recorded.should == [:no_ext]
-  end
+  describe "(path resolution)" do
+    # This behavior is specific to Kernel#load, it differs for Kernel#require
+    it "loads a non-extensioned file as a Ruby source file" do
+      path = File.expand_path "load_fixture", CODE_LOADING_DIR
+      @object.load(path).should == true
+      ScratchPad.recorded.should == [:no_ext]
+    end
 
-  it "loads a non .rb extensioned file as a Ruby source file" do
-    path = File.expand_path "load_fixture.ext", CODE_LOADING_DIR
-    @object.load(path).should be_true
-    ScratchPad.recorded.should == [:no_rb_ext]
-  end
+    it "loads a non .rb extensioned file as a Ruby source file" do
+      path = File.expand_path "load_fixture.ext", CODE_LOADING_DIR
+      @object.load(path).should == true
+      ScratchPad.recorded.should == [:no_rb_ext]
+    end
 
-  it "loads from the current working directory" do
-    Dir.chdir CODE_LOADING_DIR do
-      @object.load("load_fixture.rb").should be_true
-      ScratchPad.recorded.should == [:loaded]
+    it "loads from the current working directory" do
+      Dir.chdir CODE_LOADING_DIR do
+        @object.load("load_fixture.rb").should == true
+        ScratchPad.recorded.should == [:loaded]
+      end
+    end
+
+    # This behavior is specific to Kernel#load, it differs for Kernel#require
+    it "does not look for a c-extension file when passed a path without extension (when no .rb is present)" do
+      path = File.join CODE_LOADING_DIR, "a", "load_fixture"
+      -> { @object.send(@method, path) }.should.raise(LoadError)
     end
   end
 
   it "loads a file that recursively requires itself" do
     path = File.expand_path "recursive_require_fixture.rb", CODE_LOADING_DIR
     -> {
-      @object.load(path).should be_true
+      @object.load(path).should == true
     }.should complain(/circular require considered harmful/, verbose: true)
     ScratchPad.recorded.should == [:loaded, :loaded]
   end
 
   it "loads a file that recursively loads itself" do
     path = File.expand_path "recursive_load_fixture.rb", CODE_LOADING_DIR
-    @object.load(path).should be_true
+    @object.load(path).should == true
     ScratchPad.recorded.should == [:loaded, :loaded]
   end
 
   it "loads a file each time the method is called" do
-    @object.load(@path).should be_true
-    @object.load(@path).should be_true
+    @object.load(@path).should == true
+    @object.load(@path).should == true
     ScratchPad.recorded.should == [:loaded, :loaded]
   end
 
   it "loads a file even when the name appears in $LOADED_FEATURES" do
     $LOADED_FEATURES << @path
-    @object.load(@path).should be_true
+    @object.load(@path).should == true
     ScratchPad.recorded.should == [:loaded]
   end
 
   it "loads a file that has been loaded by #require" do
-    @object.require(@path).should be_true
-    @object.load(@path).should be_true
+    @object.require(@path).should == true
+    @object.load(@path).should == true
     ScratchPad.recorded.should == [:loaded, :loaded]
   end
 
   it "loads file even after $LOAD_PATH change" do
     $LOAD_PATH << CODE_LOADING_DIR
-    @object.load("load_fixture.rb").should be_true
+    @object.load("load_fixture.rb").should == true
     $LOAD_PATH.unshift CODE_LOADING_DIR + "/gem"
-    @object.load("load_fixture.rb").should be_true
+    @object.load("load_fixture.rb").should == true
     ScratchPad.recorded.should == [:loaded, :loaded_gem]
   end
 
   it "does not cause #require with the same path to fail" do
-    @object.load(@path).should be_true
-    @object.require(@path).should be_true
+    @object.load(@path).should == true
+    @object.require(@path).should == true
     ScratchPad.recorded.should == [:loaded, :loaded]
   end
 
   it "does not add the loaded path to $LOADED_FEATURES" do
     saved_loaded_features = $LOADED_FEATURES.dup
-    @object.load(@path).should be_true
+    @object.load(@path).should == true
     $LOADED_FEATURES.should == saved_loaded_features
   end
 
   it "raises a LoadError if passed a non-extensioned path that does not exist but a .rb extensioned path does exist" do
     path = File.expand_path "load_ext_fixture", CODE_LOADING_DIR
-    -> { @object.load(path) }.should raise_error(LoadError)
+    -> { @object.load(path) }.should.raise(LoadError)
   end
 
   describe "when passed true for 'wrap'" do
     it "loads from an existing path" do
-      path = File.expand_path "wrap_fixture.rb", CODE_LOADING_DIR
-      @object.load(path, true).should be_true
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      @object.load(path, true).should == true
     end
 
     it "sets the enclosing scope to an anonymous module" do
-      path = File.expand_path "wrap_fixture.rb", CODE_LOADING_DIR
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
       @object.load(path, true)
 
-      Object.const_defined?(:LoadSpecWrap).should be_false
+      Object.const_defined?(:LoadSpecWrap).should == false
+
+      wrap_module = ScratchPad.recorded[1]
+      wrap_module.should.instance_of?(Module)
     end
 
     it "allows referencing outside namespaces" do
-      path = File.expand_path "wrap_fixture.rb", CODE_LOADING_DIR
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      @object.load(path, true)
+
+      ScratchPad.recorded[0].should.equal?(String)
+    end
+
+    it "sets self as a copy of the top-level main" do
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      @object.load(path, true)
+
+      top_level = ScratchPad.recorded[2]
+      top_level.to_s.should == "main"
+      top_level.method(:to_s).owner.should == top_level.singleton_class
+      top_level.should_not.equal?(main)
+      top_level.should.instance_of?(Object)
+    end
+
+    it "includes modules included in main's singleton class in self's class" do
+      mod = Module.new
+      main.extend(mod)
+
+      main_ancestors = main.singleton_class.ancestors[1..-1]
+      main_ancestors.first.should == mod
+
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
       @object.load(path, true)
 
-      ScratchPad.recorded.first.should be_an_instance_of(Class)
+      top_level = ScratchPad.recorded[2]
+      top_level_ancestors = top_level.singleton_class.ancestors[-main_ancestors.size..-1]
+      top_level_ancestors.should == main_ancestors
+
+      wrap_module = ScratchPad.recorded[1]
+      top_level.singleton_class.ancestors.should == [top_level.singleton_class, wrap_module, *main_ancestors]
     end
 
     describe "with top-level methods" do
@@ -115,11 +159,44 @@ describe :kernel_load, shared: true do
       end
 
       it "does not pollute the receiver" do
-        -> { @object.send(:top_level_method) }.should raise_error(NameError)
+        -> { @object.send(:top_level_method) }.should.raise(NameError)
       end
     end
   end
 
+  describe "when passed a module for 'wrap'" do
+    it "sets the enclosing scope to the supplied module" do
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      mod = Module.new
+      @object.load(path, mod)
+
+      Object.const_defined?(:LoadSpecWrap).should == false
+      mod.const_defined?(:LoadSpecWrap).should == true
+
+      wrap_module = ScratchPad.recorded[1]
+      wrap_module.should == mod
+    end
+
+    it "makes constants and instance methods in the source file reachable with the supplied module" do
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      mod = Module.new
+      @object.load(path, mod)
+
+      mod::LOAD_WRAP_SPECS_TOP_LEVEL_CONSTANT.should == 1
+      obj = Object.new
+      obj.extend(mod)
+      obj.send(:load_wrap_specs_top_level_method).should == :load_wrap_specs_top_level_method
+    end
+
+    it "makes instance methods in the source file private" do
+      path = File.expand_path "load_wrap_fixture.rb", CODE_LOADING_DIR
+      mod = Module.new
+      @object.load(path, mod)
+
+      mod.private_instance_methods.include?(:load_wrap_specs_top_level_method).should == true
+    end
+  end
+
   describe "(shell expansion)" do
     before :each do
       @env_home = ENV["HOME"]
@@ -131,7 +208,7 @@ describe :kernel_load, shared: true do
     end
 
     it "expands a tilde to the HOME environment variable as the path to load" do
-      @object.require("~/load_fixture.rb").should be_true
+      @object.require("~/load_fixture.rb").should == true
       ScratchPad.recorded.should == [:loaded]
     end
   end
diff --git a/spec/ruby/core/kernel/shared/method.rb b/spec/ruby/core/kernel/shared/method.rb
index 3418966b1b..82abc287d1 100644
--- a/spec/ruby/core/kernel/shared/method.rb
+++ b/spec/ruby/core/kernel/shared/method.rb
@@ -4,20 +4,26 @@ describe :kernel_method, shared: true do
   it "returns a method object for a valid method" do
     class KernelSpecs::Foo; def bar; 'done'; end; end
     m = KernelSpecs::Foo.new.send(@method, :bar)
-    m.should be_an_instance_of Method
+    m.should.instance_of? Method
     m.call.should == 'done'
   end
 
   it "returns a method object for a valid singleton method" do
     class KernelSpecs::Foo; def self.bar; 'class done'; end; end
     m = KernelSpecs::Foo.send(@method, :bar)
-    m.should be_an_instance_of Method
+    m.should.instance_of? Method
     m.call.should == 'class done'
   end
 
-  it "returns a method object if we repond_to_missing? method" do
+  it "returns a method object if respond_to_missing?(method) is true" do
     m = KernelSpecs::RespondViaMissing.new.send(@method, :handled_publicly)
-    m.should be_an_instance_of Method
+    m.should.instance_of? Method
+    m.call(42).should == "Done handled_publicly([42])"
+  end
+
+  it "the returned method object if respond_to_missing?(method) calls #method_missing with a Symbol name" do
+    m = KernelSpecs::RespondViaMissing.new.send(@method, "handled_publicly")
+    m.should.instance_of? Method
     m.call(42).should == "Done handled_publicly([42])"
   end
 
@@ -25,12 +31,12 @@ describe :kernel_method, shared: true do
     class KernelSpecs::Foo; def bar; 'done'; end; end
     -> {
       KernelSpecs::Foo.new.send(@method, :invalid_and_silly_method_name)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "raises a NameError for an invalid singleton method name" do
     class KernelSpecs::Foo; def self.bar; 'done'; end; end
-    -> { KernelSpecs::Foo.send(@method, :baz) }.should raise_error(NameError)
+    -> { KernelSpecs::Foo.send(@method, :baz) }.should.raise(NameError)
   end
 
   it "changes the method called for super on a target aliased method" do
diff --git a/spec/ruby/core/kernel/shared/require.rb b/spec/ruby/core/kernel/shared/require.rb
index 52089f22fe..6272b00665 100644
--- a/spec/ruby/core/kernel/shared/require.rb
+++ b/spec/ruby/core/kernel/shared/require.rb
@@ -2,26 +2,26 @@ describe :kernel_require_basic, shared: true do
   describe "(path resolution)" do
     it "loads an absolute path" do
       path = File.expand_path "load_fixture.rb", CODE_LOADING_DIR
-      @object.send(@method, path).should be_true
+      @object.send(@method, path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "loads a non-canonical absolute path" do
       path = File.join CODE_LOADING_DIR, "..", "code", "load_fixture.rb"
-      @object.send(@method, path).should be_true
+      @object.send(@method, path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "loads a file defining many methods" do
       path = File.expand_path "methods_fixture.rb", CODE_LOADING_DIR
-      @object.send(@method, path).should be_true
+      @object.send(@method, path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "raises a LoadError if the file does not exist" do
       path = File.expand_path "nonexistent.rb", CODE_LOADING_DIR
       File.should_not.exist?(path)
-      -> { @object.send(@method, path) }.should raise_error(LoadError)
+      -> { @object.send(@method, path) }.should.raise(LoadError)
       ScratchPad.recorded.should == []
     end
 
@@ -42,7 +42,7 @@ describe :kernel_require_basic, shared: true do
 
           it "raises a LoadError" do
             File.should.exist?(@path)
-            -> { @object.send(@method, @path) }.should raise_error(LoadError)
+            -> { @object.send(@method, @path) }.should.raise(LoadError)
           end
         end
       end
@@ -52,24 +52,24 @@ describe :kernel_require_basic, shared: true do
       path = File.expand_path "load_fixture.rb", CODE_LOADING_DIR
       name = mock("load_fixture.rb mock")
       name.should_receive(:to_str).and_return(path)
-      @object.send(@method, name).should be_true
+      @object.send(@method, name).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "raises a TypeError if passed nil" do
-      -> { @object.send(@method, nil) }.should raise_error(TypeError)
+      -> { @object.send(@method, nil) }.should.raise(TypeError)
     end
 
-    it "raises a TypeError if passed a Fixnum" do
-      -> { @object.send(@method, 42) }.should raise_error(TypeError)
+    it "raises a TypeError if passed an Integer" do
+      -> { @object.send(@method, 42) }.should.raise(TypeError)
     end
 
     it "raises a TypeError if passed an Array" do
-      -> { @object.send(@method, []) }.should raise_error(TypeError)
+      -> { @object.send(@method, []) }.should.raise(TypeError)
     end
 
     it "raises a TypeError if passed an object that does not provide #to_str" do
-      -> { @object.send(@method, mock("not a filename")) }.should raise_error(TypeError)
+      -> { @object.send(@method, mock("not a filename")) }.should.raise(TypeError)
     end
 
     it "raises a TypeError if passed an object that has #to_s but not #to_str" do
@@ -77,14 +77,14 @@ describe :kernel_require_basic, shared: true do
       name.stub!(:to_s).and_return("load_fixture.rb")
       $LOAD_PATH << "."
       Dir.chdir CODE_LOADING_DIR do
-        -> { @object.send(@method, name) }.should raise_error(TypeError)
+        -> { @object.send(@method, name) }.should.raise(TypeError)
       end
     end
 
     it "raises a TypeError if #to_str does not return a String" do
       name = mock("#to_str returns nil")
       name.should_receive(:to_str).at_least(1).times.and_return(nil)
-      -> { @object.send(@method, name) }.should raise_error(TypeError)
+      -> { @object.send(@method, name) }.should.raise(TypeError)
     end
 
     it "calls #to_path on non-String objects" do
@@ -92,7 +92,7 @@ describe :kernel_require_basic, shared: true do
       name.stub!(:to_path).and_return("load_fixture.rb")
       $LOAD_PATH << "."
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, name).should be_true
+        @object.send(@method, name).should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -101,7 +101,7 @@ describe :kernel_require_basic, shared: true do
       path = File.expand_path "load_fixture.rb", CODE_LOADING_DIR
       str = mock("load_fixture.rb mock")
       str.should_receive(:to_path).and_return(path)
-      @object.send(@method, str).should be_true
+      @object.send(@method, str).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -111,21 +111,21 @@ describe :kernel_require_basic, shared: true do
       to_path = mock("load_fixture_rb #to_path mock")
       name.should_receive(:to_path).and_return(to_path)
       to_path.should_receive(:to_str).and_return(path)
-      @object.send(@method, name).should be_true
+      @object.send(@method, name).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     # "http://redmine.ruby-lang.org/issues/show/2578"
     it "loads a ./ relative path from the current working directory with empty $LOAD_PATH" do
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, "./load_fixture.rb").should be_true
+        @object.send(@method, "./load_fixture.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "loads a ../ relative path from the current working directory with empty $LOAD_PATH" do
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, "../code/load_fixture.rb").should be_true
+        @object.send(@method, "../code/load_fixture.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -133,7 +133,7 @@ describe :kernel_require_basic, shared: true do
     it "loads a ./ relative path from the current working directory with non-empty $LOAD_PATH" do
       $LOAD_PATH << "an_irrelevant_dir"
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, "./load_fixture.rb").should be_true
+        @object.send(@method, "./load_fixture.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -141,7 +141,7 @@ describe :kernel_require_basic, shared: true do
     it "loads a ../ relative path from the current working directory with non-empty $LOAD_PATH" do
       $LOAD_PATH << "an_irrelevant_dir"
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, "../code/load_fixture.rb").should be_true
+        @object.send(@method, "../code/load_fixture.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -149,22 +149,30 @@ describe :kernel_require_basic, shared: true do
     it "loads a non-canonical path from the current working directory with non-empty $LOAD_PATH" do
       $LOAD_PATH << "an_irrelevant_dir"
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, "../code/../code/load_fixture.rb").should be_true
+        @object.send(@method, "../code/../code/load_fixture.rb").should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "resolves a filename against $LOAD_PATH entries" do
       $LOAD_PATH << CODE_LOADING_DIR
-      @object.send(@method, "load_fixture.rb").should be_true
+      @object.send(@method, "load_fixture.rb").should == true
+      ScratchPad.recorded.should == [:loaded]
+    end
+
+    it "accepts an Object with #to_path in $LOAD_PATH" do
+      obj = mock("to_path")
+      obj.should_receive(:to_path).at_least(:once).and_return(CODE_LOADING_DIR)
+      $LOAD_PATH << obj
+      @object.send(@method, "load_fixture.rb").should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "does not require file twice after $LOAD_PATH change" do
       $LOAD_PATH << CODE_LOADING_DIR
-      @object.require("load_fixture.rb").should be_true
+      @object.require("load_fixture.rb").should == true
       $LOAD_PATH.push CODE_LOADING_DIR + "/gem"
-      @object.require("load_fixture.rb").should be_false
+      @object.require("load_fixture.rb").should == false
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -172,7 +180,7 @@ describe :kernel_require_basic, shared: true do
       $LOAD_PATH << CODE_LOADING_DIR
       -> do
         @object.send(@method, "./load_fixture.rb")
-      end.should raise_error(LoadError)
+      end.should.raise(LoadError)
       ScratchPad.recorded.should == []
     end
 
@@ -180,13 +188,13 @@ describe :kernel_require_basic, shared: true do
       $LOAD_PATH << CODE_LOADING_DIR
       -> do
         @object.send(@method, "../code/load_fixture.rb")
-      end.should raise_error(LoadError)
+      end.should.raise(LoadError)
       ScratchPad.recorded.should == []
     end
 
     it "resolves a non-canonical path against $LOAD_PATH entries" do
       $LOAD_PATH << File.dirname(CODE_LOADING_DIR)
-      @object.send(@method, "code/../code/load_fixture.rb").should be_true
+      @object.send(@method, "code/../code/load_fixture.rb").should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -195,7 +203,7 @@ describe :kernel_require_basic, shared: true do
       sep = File::Separator + File::Separator
       path = ["..", "code", "load_fixture.rb"].join(sep)
       Dir.chdir CODE_LOADING_DIR do
-        @object.send(@method, path).should be_true
+        @object.send(@method, path).should == true
       end
       ScratchPad.recorded.should == [:loaded]
     end
@@ -204,11 +212,39 @@ end
 
 describe :kernel_require, shared: true do
   describe "(path resolution)" do
+    it "loads .rb file when passed absolute path without extension" do
+      path = File.expand_path "load_fixture", CODE_LOADING_DIR
+      @object.send(@method, path).should == true
+      # This should _not_ be [:no_ext]
+      ScratchPad.recorded.should == [:loaded]
+    end
+
+    platform_is :linux, :darwin do
+      it "loads c-extension file when passed absolute path without extension when no .rb is present" do
+        # the error message is specific to what dlerror() returns
+        path = File.join CODE_LOADING_DIR, "a", "load_fixture"
+        -> { @object.send(@method, path) }.should.raise(LoadError)
+      end
+    end
+
+    platform_is :darwin do
+      it "loads .bundle file when passed absolute path with .so" do
+        # the error message is specific to what dlerror() returns
+        path = File.join CODE_LOADING_DIR, "a", "load_fixture.so"
+        -> { @object.send(@method, path) }.should.raise(LoadError)
+      end
+    end
+
+    it "does not try an extra .rb if the path already ends in .rb" do
+      path = File.join CODE_LOADING_DIR, "d", "load_fixture.rb"
+      -> { @object.send(@method, path) }.should.raise(LoadError)
+    end
+
     # For reference see [ruby-core:24155] in which matz confirms this feature is
     # intentional for security reasons.
     it "does not load a bare filename unless the current working directory is in $LOAD_PATH" do
       Dir.chdir CODE_LOADING_DIR do
-        -> { @object.require("load_fixture.rb") }.should raise_error(LoadError)
+        -> { @object.require("load_fixture.rb") }.should.raise(LoadError)
         ScratchPad.recorded.should == []
       end
     end
@@ -217,7 +253,7 @@ describe :kernel_require, shared: true do
       Dir.chdir File.dirname(CODE_LOADING_DIR) do
         -> do
           @object.require("code/load_fixture.rb")
-        end.should raise_error(LoadError)
+        end.should.raise(LoadError)
         ScratchPad.recorded.should == []
       end
     end
@@ -225,10 +261,19 @@ describe :kernel_require, shared: true do
     it "loads a file that recursively requires itself" do
       path = File.expand_path "recursive_require_fixture.rb", CODE_LOADING_DIR
       -> {
-        @object.require(path).should be_true
+        @object.require(path).should == true
       }.should complain(/circular require considered harmful/, verbose: true)
       ScratchPad.recorded.should == [:loaded]
     end
+
+    it "loads a file concurrently" do
+      path = File.expand_path "concurrent_require_fixture.rb", CODE_LOADING_DIR
+      ScratchPad.record(@object)
+      -> {
+        @object.require(path)
+      }.should_not complain(/circular require considered harmful/, verbose: true)
+      ScratchPad.recorded.join
+    end
   end
 
   describe "(non-extensioned path)" do
@@ -239,16 +284,33 @@ describe :kernel_require, shared: true do
     end
 
     it "loads a .rb extensioned file when a C-extension file exists on an earlier load path" do
-      @object.require("load_fixture").should be_true
+      @object.require("load_fixture").should == true
       ScratchPad.recorded.should == [:loaded]
     end
+
+    it "does not load a feature twice when $LOAD_PATH has been modified" do
+      $LOAD_PATH.replace [CODE_LOADING_DIR]
+      @object.require("load_fixture").should == true
+      $LOAD_PATH.replace [File.expand_path("b", CODE_LOADING_DIR), CODE_LOADING_DIR]
+      @object.require("load_fixture").should == false
+    end
+
+    it "stores the missing path in a LoadError object" do
+      path = "abcd1234"
+
+      -> {
+        @object.send(@method, path)
+      }.should.raise(LoadError) { |e|
+        e.path.should == path
+      }
+    end
   end
 
   describe "(file extensions)" do
     it "loads a .rb extensioned file when passed a non-extensioned path" do
       path = File.expand_path "load_fixture", CODE_LOADING_DIR
       File.should.exist?(path)
-      @object.require(path).should be_true
+      @object.require(path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -258,21 +320,21 @@ describe :kernel_require, shared: true do
       $LOADED_FEATURES << File.expand_path("load_fixture.so", CODE_LOADING_DIR)
       $LOADED_FEATURES << File.expand_path("load_fixture.dll", CODE_LOADING_DIR)
       path = File.expand_path "load_fixture", CODE_LOADING_DIR
-      @object.require(path).should be_true
+      @object.require(path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "does not load a C-extension file if a .rb extensioned file is already loaded" do
       $LOADED_FEATURES << File.expand_path("load_fixture.rb", CODE_LOADING_DIR)
       path = File.expand_path "load_fixture", CODE_LOADING_DIR
-      @object.require(path).should be_false
+      @object.require(path).should == false
       ScratchPad.recorded.should == []
     end
 
     it "loads a .rb extensioned file when passed a non-.rb extensioned path" do
       path = File.expand_path "load_fixture.ext", CODE_LOADING_DIR
       File.should.exist?(path)
-      @object.require(path).should be_true
+      @object.require(path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
@@ -282,14 +344,14 @@ describe :kernel_require, shared: true do
       $LOADED_FEATURES << File.expand_path("load_fixture.ext.so", CODE_LOADING_DIR)
       $LOADED_FEATURES << File.expand_path("load_fixture.ext.dll", CODE_LOADING_DIR)
       path = File.expand_path "load_fixture.ext", CODE_LOADING_DIR
-      @object.require(path).should be_true
+      @object.require(path).should == true
       ScratchPad.recorded.should == [:loaded]
     end
 
     it "does not load a C-extension file if a complex-extensioned .rb file is already loaded" do
       $LOADED_FEATURES << File.expand_path("load_fixture.ext.rb", CODE_LOADING_DIR)
       path = File.expand_path "load_fixture.ext", CODE_LOADING_DIR
-      @object.require(path).should be_false
+      @object.require(path).should == false
       ScratchPad.recorded.should == []
     end
   end
@@ -300,8 +362,8 @@ describe :kernel_require, shared: true do
     end
 
     it "stores an absolute path" do
-      @object.require(@path).should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require(@path).should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     platform_is_not :windows do
@@ -321,20 +383,35 @@ describe :kernel_require, shared: true do
         it "does not canonicalize the path and stores a path with symlinks" do
           symlink_path = "#{@symlink_to_code_dir}/load_fixture.rb"
           canonical_path = "#{CODE_LOADING_DIR}/load_fixture.rb"
-          @object.require(symlink_path).should be_true
+          @object.require(symlink_path).should == true
           ScratchPad.recorded.should == [:loaded]
 
           features = $LOADED_FEATURES.select { |path| path.end_with?('load_fixture.rb') }
-          features.should include(symlink_path)
-          features.should_not include(canonical_path)
+          features.should.include?(symlink_path)
+          features.should_not.include?(canonical_path)
         end
 
         it "stores the same path that __FILE__ returns in the required file" do
           symlink_path = "#{@symlink_to_code_dir}/load_fixture_and__FILE__.rb"
-          @object.require(symlink_path).should be_true
+          @object.require(symlink_path).should == true
           loaded_feature = $LOADED_FEATURES.last
           ScratchPad.recorded.should == [loaded_feature]
         end
+
+        it "requires only once when a new matching file added to path" do
+          @object.require('load_fixture').should == true
+          ScratchPad.recorded.should == [:loaded]
+
+          symlink_to_code_dir_two = tmp("codesymlinktwo")
+          File.symlink("#{CODE_LOADING_DIR}/b", symlink_to_code_dir_two)
+          begin
+            $LOAD_PATH.unshift(symlink_to_code_dir_two)
+
+            @object.require('load_fixture').should == false
+          ensure
+            rm_r symlink_to_code_dir_two
+          end
+        end
       end
 
       describe "with symlinks in the required feature and $LOAD_PATH" do
@@ -354,26 +431,13 @@ describe :kernel_require, shared: true do
           rm_r @dir, @symlink_to_dir
         end
 
-        ruby_version_is ""..."2.4.4" do
-          it "canonicalizes neither the entry in $LOAD_PATH nor the filename passed to #require" do
-            $LOAD_PATH.unshift(@symlink_to_dir)
-            @object.require("symfile").should be_true
-            loaded_feature = "#{@symlink_to_dir}/symfile.rb"
-            ScratchPad.recorded.should == [loaded_feature]
-            $".last.should == loaded_feature
-            $LOAD_PATH[0].should == @symlink_to_dir
-          end
-        end
-
-        ruby_version_is "2.4.4" do
-          it "canonicalizes the entry in $LOAD_PATH but not the filename passed to #require" do
-            $LOAD_PATH.unshift(@symlink_to_dir)
-            @object.require("symfile").should be_true
-            loaded_feature = "#{@dir}/symfile.rb"
-            ScratchPad.recorded.should == [loaded_feature]
-            $".last.should == loaded_feature
-            $LOAD_PATH[0].should == @symlink_to_dir
-          end
+        it "canonicalizes the entry in $LOAD_PATH but not the filename passed to #require" do
+          $LOAD_PATH.unshift(@symlink_to_dir)
+          @object.require("symfile").should == true
+          loaded_feature = "#{@dir}/symfile.rb"
+          ScratchPad.recorded.should == [loaded_feature]
+          $".last.should == loaded_feature
+          $LOAD_PATH[0].should == @symlink_to_dir
         end
       end
     end
@@ -381,20 +445,20 @@ describe :kernel_require, shared: true do
     it "does not store the path if the load fails" do
       $LOAD_PATH << CODE_LOADING_DIR
       saved_loaded_features = $LOADED_FEATURES.dup
-      -> { @object.require("raise_fixture.rb") }.should raise_error(RuntimeError)
+      -> { @object.require("raise_fixture.rb") }.should.raise(RuntimeError)
       $LOADED_FEATURES.should == saved_loaded_features
     end
 
     it "does not load an absolute path that is already stored" do
       $LOADED_FEATURES << @path
-      @object.require(@path).should be_false
+      @object.require(@path).should == false
       ScratchPad.recorded.should == []
     end
 
     it "does not load a ./ relative path that is already stored" do
       $LOADED_FEATURES << "./load_fixture.rb"
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("./load_fixture.rb").should be_false
+        @object.require("./load_fixture.rb").should == false
       end
       ScratchPad.recorded.should == []
     end
@@ -402,7 +466,7 @@ describe :kernel_require, shared: true do
     it "does not load a ../ relative path that is already stored" do
       $LOADED_FEATURES << "../load_fixture.rb"
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("../load_fixture.rb").should be_false
+        @object.require("../load_fixture.rb").should == false
       end
       ScratchPad.recorded.should == []
     end
@@ -410,27 +474,27 @@ describe :kernel_require, shared: true do
     it "does not load a non-canonical path that is already stored" do
       $LOADED_FEATURES << "code/../code/load_fixture.rb"
       $LOAD_PATH << File.dirname(CODE_LOADING_DIR)
-      @object.require("code/../code/load_fixture.rb").should be_false
+      @object.require("code/../code/load_fixture.rb").should == false
       ScratchPad.recorded.should == []
     end
 
     it "respects being replaced with a new array" do
       prev = $LOADED_FEATURES.dup
 
-      @object.require(@path).should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require(@path).should == true
+      $LOADED_FEATURES.should.include?(@path)
 
       $LOADED_FEATURES.replace(prev)
 
-      $LOADED_FEATURES.should_not include(@path)
-      @object.require(@path).should be_true
-      $LOADED_FEATURES.should include(@path)
+      $LOADED_FEATURES.should_not.include?(@path)
+      @object.require(@path).should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "does not load twice the same file with and without extension" do
       $LOAD_PATH << CODE_LOADING_DIR
-      @object.require("load_fixture.rb").should be_true
-      @object.require("load_fixture").should be_false
+      @object.require("load_fixture.rb").should == true
+      @object.require("load_fixture").should == false
     end
 
     describe "when a non-extensioned file is in $LOADED_FEATURES" do
@@ -440,19 +504,19 @@ describe :kernel_require, shared: true do
 
       it "loads a .rb extensioned file when a non extensioned file is in $LOADED_FEATURES" do
         $LOAD_PATH << CODE_LOADING_DIR
-        @object.require("load_fixture").should be_true
+        @object.require("load_fixture").should == true
         ScratchPad.recorded.should == [:loaded]
       end
 
       it "loads a .rb extensioned file from a subdirectory" do
         $LOAD_PATH << File.dirname(CODE_LOADING_DIR)
-        @object.require("code/load_fixture").should be_true
+        @object.require("code/load_fixture").should == true
         ScratchPad.recorded.should == [:loaded]
       end
 
       it "returns false if the file is not found" do
         Dir.chdir File.dirname(CODE_LOADING_DIR) do
-          @object.require("load_fixture").should be_false
+          @object.require("load_fixture").should == false
           ScratchPad.recorded.should == []
         end
       end
@@ -460,7 +524,7 @@ describe :kernel_require, shared: true do
       it "returns false when passed a path and the file is not found" do
         $LOADED_FEATURES << "code/load_fixture"
         Dir.chdir CODE_LOADING_DIR do
-          @object.require("code/load_fixture").should be_false
+          @object.require("code/load_fixture").should == false
           ScratchPad.recorded.should == []
         end
       end
@@ -468,16 +532,16 @@ describe :kernel_require, shared: true do
 
     it "stores ../ relative paths as absolute paths" do
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("../code/load_fixture.rb").should be_true
+        @object.require("../code/load_fixture.rb").should == true
       end
-      $LOADED_FEATURES.should include(@path)
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "stores ./ relative paths as absolute paths" do
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("./load_fixture.rb").should be_true
+        @object.require("./load_fixture.rb").should == true
       end
-      $LOADED_FEATURES.should include(@path)
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "collapses duplicate path separators" do
@@ -485,27 +549,27 @@ describe :kernel_require, shared: true do
       sep = File::Separator + File::Separator
       path = ["..", "code", "load_fixture.rb"].join(sep)
       Dir.chdir CODE_LOADING_DIR do
-        @object.require(path).should be_true
+        @object.require(path).should == true
       end
-      $LOADED_FEATURES.should include(@path)
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "expands absolute paths containing .." do
       path = File.join CODE_LOADING_DIR, "..", "code", "load_fixture.rb"
-      @object.require(path).should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require(path).should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "adds the suffix of the resolved filename" do
       $LOAD_PATH << CODE_LOADING_DIR
-      @object.require("load_fixture").should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require("load_fixture").should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "does not load a non-canonical path for a file already loaded" do
       $LOADED_FEATURES << @path
       $LOAD_PATH << File.dirname(CODE_LOADING_DIR)
-      @object.require("code/../code/load_fixture.rb").should be_false
+      @object.require("code/../code/load_fixture.rb").should == false
       ScratchPad.recorded.should == []
     end
 
@@ -513,7 +577,7 @@ describe :kernel_require, shared: true do
       $LOADED_FEATURES << @path
       $LOAD_PATH << "an_irrelevant_dir"
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("./load_fixture.rb").should be_false
+        @object.require("./load_fixture.rb").should == false
       end
       ScratchPad.recorded.should == []
     end
@@ -522,46 +586,35 @@ describe :kernel_require, shared: true do
       $LOADED_FEATURES << @path
       $LOAD_PATH << "an_irrelevant_dir"
       Dir.chdir CODE_LOADING_DIR do
-        @object.require("../code/load_fixture.rb").should be_false
+        @object.require("../code/load_fixture.rb").should == false
       end
       ScratchPad.recorded.should == []
     end
 
-    ruby_version_is ""..."2.5" do
-      it "complex, enumerator, rational, thread and unicode_normalize are already required" do
-        provided = %w[complex enumerator rational thread unicode_normalize]
-        features = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems')
-        provided.each { |feature|
-          features.should =~ /\b#{feature}\.(rb|so|jar)$/
-        }
+    it "unicode_normalize is part of core and not $LOADED_FEATURES" do
+      features = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems')
+      features.lines.each { |feature|
+        feature.should_not.include?("unicode_normalize")
+      }
 
-        code = provided.map { |f| "puts require #{f.inspect}\n" }.join
-        required = ruby_exe(code, options: '--disable-gems')
-        required.should == "false\n" * provided.size
-      end
+      -> { @object.require("unicode_normalize") }.should.raise(LoadError)
     end
 
-    ruby_version_is "2.5" do
-      it "complex, enumerator, rational and thread are already required" do
-        provided = %w[complex enumerator rational thread]
-        features = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems')
-        provided.each { |feature|
-          features.should =~ /\b#{feature}\.(rb|so|jar)$/
-        }
-
-        code = provided.map { |f| "puts require #{f.inspect}\n" }.join
-        required = ruby_exe(code, options: '--disable-gems')
-        required.should == "false\n" * provided.size
+    it "does not load a file earlier on the $LOAD_PATH when other similar features were already loaded" do
+      Dir.chdir CODE_LOADING_DIR do
+        @object.send(@method, "../code/load_fixture").should == true
       end
+      ScratchPad.recorded.should == [:loaded]
 
-      it "unicode_normalize is part of core and not $LOADED_FEATURES" do
-        features = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems')
-        features.lines.each { |feature|
-          feature.should_not include("unicode_normalize")
-        }
+      $LOAD_PATH.unshift "#{CODE_LOADING_DIR}/b"
+      # This loads because the above load was not on the $LOAD_PATH
+      @object.send(@method, "load_fixture").should == true
+      ScratchPad.recorded.should == [:loaded, :loaded]
 
-        -> { @object.require("unicode_normalize") }.should raise_error(LoadError)
-      end
+      $LOAD_PATH.unshift "#{CODE_LOADING_DIR}/c"
+      # This does not load because the above load was on the $LOAD_PATH
+      @object.send(@method, "load_fixture").should == false
+      ScratchPad.recorded.should == [:loaded, :loaded]
     end
   end
 
@@ -578,13 +631,13 @@ describe :kernel_require, shared: true do
 
     # "#3171"
     it "performs tilde expansion on a .rb file before storing paths in $LOADED_FEATURES" do
-      @object.require("~/load_fixture.rb").should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require("~/load_fixture.rb").should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
 
     it "performs tilde expansion on a non-extensioned file before storing paths in $LOADED_FEATURES" do
-      @object.require("~/load_fixture").should be_true
-      $LOADED_FEATURES.should include(@path)
+      @object.require("~/load_fixture").should == true
+      $LOADED_FEATURES.should.include?(@path)
     end
   end
 
@@ -641,8 +694,8 @@ describe :kernel_require, shared: true do
       t1.join
       t2.join
 
-      t1_res.should be_true
-      t2_res.should be_false
+      t1_res.should == true
+      t2_res.should == false
 
       ScratchPad.recorded.should == [:con_pre, :con_post, :t2_post, :t1_post]
     end
@@ -666,8 +719,8 @@ describe :kernel_require, shared: true do
       t1.join
       t2.join
 
-      t1_res.should be_true
-      t2_res.should be_true
+      t1_res.should == true
+      t2_res.should == true
 
       ScratchPad.recorded.should == [:con2_pre, :con3, :con2_post]
     end
@@ -685,7 +738,7 @@ describe :kernel_require, shared: true do
 
         -> {
           @object.require(@path)
-        }.should raise_error(RuntimeError)
+        }.should.raise(RuntimeError)
 
         Thread.pass until fin
         ScratchPad.recorded << :t1_post
@@ -706,7 +759,7 @@ describe :kernel_require, shared: true do
       t1.join
       t2.join
 
-      t2_res.should be_true
+      t2_res.should == true
 
       ScratchPad.recorded.should == [:con_pre, :con_pre, :con_post, :t2_post, :t1_post]
     end
@@ -726,7 +779,7 @@ describe :kernel_require, shared: true do
 
         -> {
           @object.require(@path)
-        }.should raise_error(RuntimeError)
+        }.should.raise(RuntimeError)
 
         raised = true
 
@@ -754,8 +807,8 @@ describe :kernel_require, shared: true do
       t1.join
       t2.join
 
-      t1_res.should be_false
-      t2_res.should be_true
+      t1_res.should == false
+      t2_res.should == true
 
       ScratchPad.recorded.should == [:con_pre, :con_pre, :con_post, :t2_post, :t1_post]
     end
@@ -766,8 +819,28 @@ describe :kernel_require, shared: true do
 
     -> {
       @object.send(@method, path)
-    }.should raise_error(LoadError) { |e|
+    }.should.raise(LoadError) { |e|
       e.path.should == path
     }
   end
+
+  platform_is :linux, :darwin do
+    it "does not store the missing path in a LoadError object when c-extension file exists but loading fails and passed absolute path without extension" do
+      # the error message is specific to what dlerror() returns
+      path = File.join CODE_LOADING_DIR, "a", "load_fixture"
+      -> { @object.send(@method, path) }.should.raise(LoadError) { |e|
+        e.path.should == nil
+      }
+    end
+  end
+
+  platform_is :darwin do
+    it "does not store the missing path in a LoadError object when c-extension file exists but loading fails and passed absolute path with extension" do
+      # the error message is specific to what dlerror() returns
+      path = File.join CODE_LOADING_DIR, "a", "load_fixture.bundle"
+      -> { @object.send(@method, path) }.should.raise(LoadError) { |e|
+        e.path.should == nil
+      }
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/shared/sprintf.rb b/spec/ruby/core/kernel/shared/sprintf.rb
index 9899684284..b40bd95f59 100644
--- a/spec/ruby/core/kernel/shared/sprintf.rb
+++ b/spec/ruby/core/kernel/shared/sprintf.rb
@@ -1,10 +1,4 @@
-require_relative '../../../shared/hash/key_error'
-
 describe :kernel_sprintf, shared: true do
-  def format(*args)
-    @method.call(*args)
-  end
-
   describe "integer formats" do
     it "converts argument into Integer with to_int" do
       obj = Object.new
@@ -12,7 +6,7 @@ describe :kernel_sprintf, shared: true do
       def obj.to_int; 10; end
 
       obj.should_receive(:to_int).and_return(10)
-      format("%b", obj).should == "1010"
+      @method.call("%b", obj).should == "1010"
     end
 
     it "converts argument into Integer with to_i if to_int isn't available" do
@@ -20,35 +14,36 @@ describe :kernel_sprintf, shared: true do
       def obj.to_i; 10; end
 
       obj.should_receive(:to_i).and_return(10)
-      format("%b", obj).should == "1010"
+      @method.call("%b", obj).should == "1010"
     end
 
     it "converts String argument with Kernel#Integer" do
-      format("%d", "0b1010").should == "10"
-      format("%d", "112").should == "112"
-      format("%d", "0127").should == "87"
-      format("%d", "0xc4").should == "196"
+      @method.call("%d", "0b1010").should == "10"
+      @method.call("%d", "112").should == "112"
+      @method.call("%d", "0127").should == "87"
+      @method.call("%d", "0xc4").should == "196"
+      @method.call("%d", "0").should == "0"
     end
 
     it "raises TypeError exception if cannot convert to Integer" do
       -> {
-        format("%b", Object.new)
-      }.should raise_error(TypeError)
+        @method.call("%b", Object.new)
+      }.should.raise(TypeError)
     end
 
     ["b", "B"].each do |f|
       describe f do
         it "converts argument as a binary number" do
-          format("%#{f}", 10).should == "1010"
+          @method.call("%#{f}", 10).should == "1010"
         end
 
         it "displays negative number as a two's complement prefixed with '..1'" do
-          format("%#{f}", -10).should == "..1" + "0110"
+          @method.call("%#{f}", -10).should == "..1" + "0110"
         end
 
         it "collapse negative number representation if it equals 1" do
-          format("%#{f}", -1).should_not == "..11"
-          format("%#{f}", -1).should == "..1"
+          @method.call("%#{f}", -1).should_not == "..11"
+          @method.call("%#{f}", -1).should == "..1"
         end
       end
     end
@@ -56,58 +51,72 @@ describe :kernel_sprintf, shared: true do
     ["d", "i", "u"].each do |f|
       describe f do
         it "converts argument as a decimal number" do
-          format("%#{f}", 112).should == "112"
-          format("%#{f}", -112).should == "-112"
+          @method.call("%#{f}", 112).should == "112"
+          @method.call("%#{f}", -112).should == "-112"
         end
 
         it "works well with large numbers" do
-          format("%#{f}", 1234567890987654321).should == "1234567890987654321"
+          @method.call("%#{f}", 1234567890987654321).should == "1234567890987654321"
         end
       end
     end
 
     describe "o" do
       it "converts argument as an octal number" do
-        format("%o", 87).should == "127"
+        @method.call("%o", 87).should == "127"
       end
 
       it "displays negative number as a two's complement prefixed with '..7'" do
-        format("%o", -87).should == "..7" + "651"
+        @method.call("%o", -87).should == "..7" + "651"
       end
 
       it "collapse negative number representation if it equals 7" do
-        format("%o", -1).should_not == "..77"
-        format("%o", -1).should == "..7"
+        @method.call("%o", -1).should_not == "..77"
+        @method.call("%o", -1).should == "..7"
       end
     end
 
     describe "x" do
       it "converts argument as a hexadecimal number" do
-        format("%x", 196).should == "c4"
+        @method.call("%x", 196).should == "c4"
       end
 
       it "displays negative number as a two's complement prefixed with '..f'" do
-        format("%x", -196).should == "..f" + "3c"
+        @method.call("%x", -196).should == "..f" + "3c"
       end
 
       it "collapse negative number representation if it equals f" do
-        format("%x", -1).should_not == "..ff"
-        format("%x", -1).should == "..f"
+        @method.call("%x", -1).should_not == "..ff"
+        @method.call("%x", -1).should == "..f"
       end
     end
 
     describe "X" do
       it "converts argument as a hexadecimal number with uppercase letters" do
-        format("%X", 196).should == "C4"
+        @method.call("%X", 196).should == "C4"
       end
 
       it "displays negative number as a two's complement prefixed with '..f'" do
-        format("%X", -196).should == "..F" + "3C"
+        @method.call("%X", -196).should == "..F" + "3C"
       end
 
       it "collapse negative number representation if it equals F" do
-        format("%X", -1).should_not == "..FF"
-        format("%X", -1).should == "..F"
+        @method.call("%X", -1).should_not == "..FF"
+        @method.call("%X", -1).should == "..F"
+      end
+    end
+
+    %w[b B d i u o x X].each do |f|
+      describe f do
+        it "converts to the empty string if precision is 0 and value is 0" do
+          @method.call("%.#{f}", 0).should == ""
+          @method.call("%.0#{f}", 0).should == ""
+        end
+
+        it "pads the empty string if precision is 0 and value is 0" do
+          @method.call("%2.#{f}", 0).should == "  "
+          @method.call("%2.0#{f}", 0).should == "  "
+        end
       end
     end
   end
@@ -116,70 +125,70 @@ describe :kernel_sprintf, shared: true do
     it "converts argument into Float" do
       obj = mock("float")
       obj.should_receive(:to_f).and_return(9.6)
-      format("%f", obj).should == "9.600000"
+      @method.call("%f", obj).should == "9.600000"
     end
 
     it "raises TypeError exception if cannot convert to Float" do
       -> {
-        format("%f", Object.new)
-      }.should raise_error(TypeError)
+        @method.call("%f", Object.new)
+      }.should.raise(TypeError)
     end
 
     {"e" => "e", "E" => "E"}.each_pair do |f, exp|
       describe f do
         it "converts argument into exponential notation [-]d.dddddde[+-]dd" do
-          format("%#{f}", 109.52).should == "1.095200#{exp}+02"
-          format("%#{f}", -109.52).should == "-1.095200#{exp}+02"
-          format("%#{f}", 0.10952).should == "1.095200#{exp}-01"
-          format("%#{f}", -0.10952).should == "-1.095200#{exp}-01"
+          @method.call("%#{f}", 109.52).should == "1.095200#{exp}+02"
+          @method.call("%#{f}", -109.52).should == "-1.095200#{exp}+02"
+          @method.call("%#{f}", 0.10952).should == "1.095200#{exp}-01"
+          @method.call("%#{f}", -0.10952).should == "-1.095200#{exp}-01"
         end
 
         it "cuts excessive digits and keeps only 6 ones" do
-          format("%#{f}", 1.123456789).should == "1.123457#{exp}+00"
+          @method.call("%#{f}", 1.123456789).should == "1.123457#{exp}+00"
         end
 
         it "rounds the last significant digit to the closest one" do
-          format("%#{f}", 1.555555555).should == "1.555556#{exp}+00"
-          format("%#{f}", -1.555555555).should == "-1.555556#{exp}+00"
-          format("%#{f}", 1.444444444).should == "1.444444#{exp}+00"
+          @method.call("%#{f}", 1.555555555).should == "1.555556#{exp}+00"
+          @method.call("%#{f}", -1.555555555).should == "-1.555556#{exp}+00"
+          @method.call("%#{f}", 1.444444444).should == "1.444444#{exp}+00"
         end
 
         it "displays Float::INFINITY as Inf" do
-          format("%#{f}", Float::INFINITY).should == "Inf"
-          format("%#{f}", -Float::INFINITY).should == "-Inf"
+          @method.call("%#{f}", Float::INFINITY).should == "Inf"
+          @method.call("%#{f}", -Float::INFINITY).should == "-Inf"
         end
 
         it "displays Float::NAN as NaN" do
-          format("%#{f}", Float::NAN).should == "NaN"
-          format("%#{f}", -Float::NAN).should == "NaN"
+          @method.call("%#{f}", Float::NAN).should == "NaN"
+          @method.call("%#{f}", -Float::NAN).should == "NaN"
         end
       end
     end
 
     describe "f" do
       it "converts floating point argument as [-]ddd.dddddd" do
-        format("%f", 10.952).should == "10.952000"
-        format("%f", -10.952).should == "-10.952000"
+        @method.call("%f", 10.952).should == "10.952000"
+        @method.call("%f", -10.952).should == "-10.952000"
       end
 
       it "cuts excessive digits and keeps only 6 ones" do
-        format("%f", 1.123456789).should == "1.123457"
+        @method.call("%f", 1.123456789).should == "1.123457"
       end
 
       it "rounds the last significant digit to the closest one" do
-        format("%f", 1.555555555).should == "1.555556"
-        format("%f", -1.555555555).should == "-1.555556"
-        format("%f", 1.444444444).should == "1.444444"
+        @method.call("%f", 1.555555555).should == "1.555556"
+        @method.call("%f", -1.555555555).should == "-1.555556"
+        @method.call("%f", 1.444444444).should == "1.444444"
       end
 
       it "displays Float::INFINITY as Inf" do
-        format("%f", Float::INFINITY).should == "Inf"
-        format("%f", -Float::INFINITY).should == "-Inf"
+        @method.call("%f", Float::INFINITY).should == "Inf"
+        @method.call("%f", -Float::INFINITY).should == "-Inf"
       end
 
       it "displays Float::NAN as NaN" do
-        format("%f", Float::NAN).should == "NaN"
-        format("%f", -Float::NAN).should == "NaN"
+        @method.call("%f", Float::NAN).should == "NaN"
+        @method.call("%f", -Float::NAN).should == "NaN"
       end
     end
 
@@ -187,100 +196,100 @@ describe :kernel_sprintf, shared: true do
       describe f do
         context "the exponent is less than -4" do
           it "converts a floating point number using exponential form" do
-            format("%#{f}", 0.0000123456).should == "1.23456#{exp}-05"
-            format("%#{f}", -0.0000123456).should == "-1.23456#{exp}-05"
+            @method.call("%#{f}", 0.0000123456).should == "1.23456#{exp}-05"
+            @method.call("%#{f}", -0.0000123456).should == "-1.23456#{exp}-05"
 
-            format("%#{f}", 0.000000000123456).should == "1.23456#{exp}-10"
-            format("%#{f}", -0.000000000123456).should == "-1.23456#{exp}-10"
+            @method.call("%#{f}", 0.000000000123456).should == "1.23456#{exp}-10"
+            @method.call("%#{f}", -0.000000000123456).should == "-1.23456#{exp}-10"
           end
         end
 
         context "the exponent is greater than or equal to the precision (6 by default)" do
           it "converts a floating point number using exponential form" do
-            format("%#{f}", 1234567).should == "1.23457#{exp}+06"
-            format("%#{f}", 1234567890123).should == "1.23457#{exp}+12"
-            format("%#{f}", -1234567).should == "-1.23457#{exp}+06"
+            @method.call("%#{f}", 1234567).should == "1.23457#{exp}+06"
+            @method.call("%#{f}", 1234567890123).should == "1.23457#{exp}+12"
+            @method.call("%#{f}", -1234567).should == "-1.23457#{exp}+06"
           end
         end
 
         context "otherwise" do
           it "converts a floating point number in dd.dddd form" do
-            format("%#{f}", 0.0001).should == "0.0001"
-            format("%#{f}", -0.0001).should == "-0.0001"
-            format("%#{f}", 123456).should == "123456"
-            format("%#{f}", -123456).should == "-123456"
+            @method.call("%#{f}", 0.0001).should == "0.0001"
+            @method.call("%#{f}", -0.0001).should == "-0.0001"
+            @method.call("%#{f}", 123456).should == "123456"
+            @method.call("%#{f}", -123456).should == "-123456"
           end
 
           it "cuts excessive digits in fractional part and keeps only 4 ones" do
-            format("%#{f}", 12.12341111).should == "12.1234"
-            format("%#{f}", -12.12341111).should == "-12.1234"
+            @method.call("%#{f}", 12.12341111).should == "12.1234"
+            @method.call("%#{f}", -12.12341111).should == "-12.1234"
           end
 
           it "rounds the last significant digit to the closest one in fractional part" do
-            format("%#{f}", 1.555555555).should == "1.55556"
-            format("%#{f}", -1.555555555).should == "-1.55556"
-            format("%#{f}", 1.444444444).should == "1.44444"
+            @method.call("%#{f}", 1.555555555).should == "1.55556"
+            @method.call("%#{f}", -1.555555555).should == "-1.55556"
+            @method.call("%#{f}", 1.444444444).should == "1.44444"
           end
 
           it "cuts fraction part to have only 6 digits at all" do
-            format("%#{f}", 1.1234567).should == "1.12346"
-            format("%#{f}", 12.1234567).should == "12.1235"
-            format("%#{f}", 123.1234567).should == "123.123"
-            format("%#{f}", 1234.1234567).should == "1234.12"
-            format("%#{f}", 12345.1234567).should == "12345.1"
-            format("%#{f}", 123456.1234567).should == "123456"
+            @method.call("%#{f}", 1.1234567).should == "1.12346"
+            @method.call("%#{f}", 12.1234567).should == "12.1235"
+            @method.call("%#{f}", 123.1234567).should == "123.123"
+            @method.call("%#{f}", 1234.1234567).should == "1234.12"
+            @method.call("%#{f}", 12345.1234567).should == "12345.1"
+            @method.call("%#{f}", 123456.1234567).should == "123456"
           end
         end
 
         it "displays Float::INFINITY as Inf" do
-          format("%#{f}", Float::INFINITY).should == "Inf"
-          format("%#{f}", -Float::INFINITY).should == "-Inf"
+          @method.call("%#{f}", Float::INFINITY).should == "Inf"
+          @method.call("%#{f}", -Float::INFINITY).should == "-Inf"
         end
 
         it "displays Float::NAN as NaN" do
-          format("%#{f}", Float::NAN).should == "NaN"
-          format("%#{f}", -Float::NAN).should == "NaN"
+          @method.call("%#{f}", Float::NAN).should == "NaN"
+          @method.call("%#{f}", -Float::NAN).should == "NaN"
         end
       end
     end
 
     describe "a" do
       it "converts floating point argument as [-]0xh.hhhhp[+-]dd" do
-        format("%a", 196).should == "0x1.88p+7"
-        format("%a", -196).should == "-0x1.88p+7"
-        format("%a", 196.1).should == "0x1.8833333333333p+7"
-        format("%a", 0.01).should == "0x1.47ae147ae147bp-7"
-        format("%a", -0.01).should == "-0x1.47ae147ae147bp-7"
+        @method.call("%a", 196).should == "0x1.88p+7"
+        @method.call("%a", -196).should == "-0x1.88p+7"
+        @method.call("%a", 196.1).should == "0x1.8833333333333p+7"
+        @method.call("%a", 0.01).should == "0x1.47ae147ae147bp-7"
+        @method.call("%a", -0.01).should == "-0x1.47ae147ae147bp-7"
       end
 
       it "displays Float::INFINITY as Inf" do
-        format("%a", Float::INFINITY).should == "Inf"
-        format("%a", -Float::INFINITY).should == "-Inf"
+        @method.call("%a", Float::INFINITY).should == "Inf"
+        @method.call("%a", -Float::INFINITY).should == "-Inf"
       end
 
       it "displays Float::NAN as NaN" do
-        format("%a", Float::NAN).should == "NaN"
-        format("%a", -Float::NAN).should == "NaN"
+        @method.call("%a", Float::NAN).should == "NaN"
+        @method.call("%a", -Float::NAN).should == "NaN"
       end
     end
 
     describe "A" do
       it "converts floating point argument as [-]0xh.hhhhp[+-]dd and use uppercase X and P" do
-        format("%A", 196).should == "0X1.88P+7"
-        format("%A", -196).should == "-0X1.88P+7"
-        format("%A", 196.1).should == "0X1.8833333333333P+7"
-        format("%A", 0.01).should == "0X1.47AE147AE147BP-7"
-        format("%A", -0.01).should == "-0X1.47AE147AE147BP-7"
+        @method.call("%A", 196).should == "0X1.88P+7"
+        @method.call("%A", -196).should == "-0X1.88P+7"
+        @method.call("%A", 196.1).should == "0X1.8833333333333P+7"
+        @method.call("%A", 0.01).should == "0X1.47AE147AE147BP-7"
+        @method.call("%A", -0.01).should == "-0X1.47AE147AE147BP-7"
       end
 
       it "displays Float::INFINITY as Inf" do
-        format("%A", Float::INFINITY).should == "Inf"
-        format("%A", -Float::INFINITY).should == "-Inf"
+        @method.call("%A", Float::INFINITY).should == "Inf"
+        @method.call("%A", -Float::INFINITY).should == "-Inf"
       end
 
       it "displays Float::NAN as NaN" do
-        format("%A", Float::NAN).should == "NaN"
-        format("%A", -Float::NAN).should == "NaN"
+        @method.call("%A", Float::NAN).should == "NaN"
+        @method.call("%A", -Float::NAN).should == "NaN"
       end
     end
   end
@@ -288,28 +297,75 @@ describe :kernel_sprintf, shared: true do
   describe "other formats" do
     describe "c" do
       it "displays character if argument is a numeric code of character" do
-        format("%c", 97).should == "a"
+        @method.call("%c", 97).should == "a"
       end
 
       it "displays character if argument is a single character string" do
-        format("%c", "a").should == "a"
+        @method.call("%c", "a").should == "a"
       end
 
-      it "raises ArgumentError if argument is a string of several characters" do
+      it "displays only the first character if argument is a string of several characters" do
+        @method.call("%c", "abc").should == "a"
+      end
+
+      it "displays only the first character if argument is a string of several multibyte characters" do
+        @method.call("%c", "あいうえお").should == "あ"
+      end
+
+      it "displays no characters if argument is an empty string" do
+        @method.call("%c", "").should == ""
+      end
+
+      it "raises TypeError if argument is not String or Integer and cannot be converted to them" do
         -> {
-          format("%c", "abc")
-        }.should raise_error(ArgumentError)
+          @method.call("%c", [])
+        }.should raise_consistent_error(TypeError, /no implicit conversion of Array into Integer/)
       end
 
-      it "raises ArgumentError if argument is an empty string" do
+      it "raises TypeError if argument is nil" do
         -> {
-          format("%c", "")
-        }.should raise_error(ArgumentError)
+          @method.call("%c", nil)
+        }.should raise_consistent_error(TypeError, /no implicit conversion of nil into Integer/)
+      end
+
+      it "tries to convert argument to String with to_str" do
+        obj = BasicObject.new
+        def obj.to_str
+          "a"
+        end
+
+        @method.call("%c", obj).should == "a"
       end
 
-      it "supports Unicode characters" do
-        format("%c", 1286).should == "Ԇ"
-        format("%c", "ش").should == "ش"
+      it "tries to convert argument to Integer with to_int" do
+        obj = BasicObject.new
+        def obj.to_int
+          90
+        end
+
+        @method.call("%c", obj).should == "Z"
+      end
+
+      it "raises TypeError if converting to String with to_str returns non-String" do
+        obj = BasicObject.new
+        def obj.to_str
+          :foo
+        end
+
+        -> {
+          @method.call("%c", obj)
+        }.should raise_consistent_error(TypeError, /can't convert BasicObject into String/)
+      end
+
+      it "raises TypeError if converting to Integer with to_int returns non-Integer" do
+        obj = BasicObject.new
+        def obj.to_int
+          :foo
+        end
+
+        -> {
+          @method.call("%c", obj)
+        }.should raise_consistent_error(TypeError, /can't convert BasicObject into Integer/)
       end
     end
 
@@ -317,19 +373,27 @@ describe :kernel_sprintf, shared: true do
       it "displays argument.inspect value" do
         obj = mock("object")
         obj.should_receive(:inspect).and_return("<inspect-result>")
-        format("%p", obj).should == "<inspect-result>"
+        @method.call("%p", obj).should == "<inspect-result>"
+      end
+
+      it "substitutes 'nil' for nil" do
+        @method.call("%p", nil).should == "nil"
       end
     end
 
     describe "s" do
       it "substitute argument passes as a string" do
-        format("%s", "abc").should == "abc"
+        @method.call("%s", "abc").should == "abc"
+      end
+
+      it "substitutes '' for nil" do
+        @method.call("%s", nil).should == ""
       end
 
       it "converts argument to string with to_s" do
         obj = mock("string")
         obj.should_receive(:to_s).and_return("abc")
-        format("%s", obj).should == "abc"
+        @method.call("%s", obj).should == "abc"
       end
 
       it "does not try to convert with to_str" do
@@ -339,29 +403,66 @@ describe :kernel_sprintf, shared: true do
         end
 
         -> {
-          format("%s", obj)
-        }.should raise_error(NoMethodError)
+          @method.call("%s", obj)
+        }.should.raise(NoMethodError)
       end
-    end
 
-    describe "%" do
-      ruby_version_is ""..."2.5" do
-        it "alone displays the percent sign" do
-          format("%").should == "%"
-        end
+      it "formats a partial substring without including omitted characters" do
+        long_string = "aabbccddhelloddccbbaa"
+        sub_string = long_string[8, 5]
+        sprintf("%.#{1 * 3}s", sub_string).should == "hel"
       end
 
-      ruby_version_is "2.5" do
-        it "alone raises an ArgumentError" do
-          -> {
-            format("%")
-          }.should raise_error(ArgumentError)
-        end
+      it "formats string with precision" do
+        Kernel.format("%.3s", "hello").should == "hel"
+        Kernel.format("%-3.3s", "hello").should == "hel"
+      end
+
+      it "formats string with width" do
+        @method.call("%6s", "abc").should == "   abc"
+        @method.call("%6s", "abcdefg").should == "abcdefg"
+      end
+
+      it "formats string with width and precision" do
+        @method.call("%4.6s", "abc").should == " abc"
+        @method.call("%4.6s", "abcdefg").should == "abcdef"
+      end
+
+      it "formats nil with width" do
+        @method.call("%6s", nil).should == "      "
+      end
+
+      it "formats nil with precision" do
+        @method.call("%.6s", nil).should == ""
+      end
+
+      it "formats nil with width and precision" do
+        @method.call("%4.6s", nil).should == "    "
+      end
+
+      it "formats multibyte string with precision" do
+        Kernel.format("%.2s", "été").should == "ét"
+      end
+
+      it "preserves encoding of the format string" do
+        str = format('%s'.encode(Encoding::UTF_8), 'foobar')
+        str.encoding.should == Encoding::UTF_8
+
+        str = format('%s'.encode(Encoding::US_ASCII), 'foobar')
+        str.encoding.should == Encoding::US_ASCII
+      end
+    end
+
+    describe "%" do
+      it "alone raises an ArgumentError" do
+        -> {
+          @method.call("%")
+        }.should.raise(ArgumentError)
       end
 
       it "is escaped by %" do
-        format("%%").should == "%"
-        format("%%d", 10).should == "%d"
+        @method.call("%%").should == "%"
+        @method.call("%%d").should == "%d"
       end
     end
   end
@@ -370,173 +471,190 @@ describe :kernel_sprintf, shared: true do
     describe "space" do
       context "applies to numeric formats bBdiouxXeEfgGaA" do
         it "leaves a space at the start of non-negative numbers" do
-          format("% b", 10).should == " 1010"
-          format("% B", 10).should == " 1010"
-          format("% d", 112).should == " 112"
-          format("% i", 112).should == " 112"
-          format("% o", 87).should == " 127"
-          format("% u", 112).should == " 112"
-          format("% x", 196).should == " c4"
-          format("% X", 196).should == " C4"
-
-          format("% e", 109.52).should == " 1.095200e+02"
-          format("% E", 109.52).should == " 1.095200E+02"
-          format("% f", 10.952).should == " 10.952000"
-          format("% g", 12.1234).should == " 12.1234"
-          format("% G", 12.1234).should == " 12.1234"
-          format("% a", 196).should == " 0x1.88p+7"
-          format("% A", 196).should == " 0X1.88P+7"
+          @method.call("% b", 10).should == " 1010"
+          @method.call("% B", 10).should == " 1010"
+          @method.call("% d", 112).should == " 112"
+          @method.call("% i", 112).should == " 112"
+          @method.call("% o", 87).should == " 127"
+          @method.call("% u", 112).should == " 112"
+          @method.call("% x", 196).should == " c4"
+          @method.call("% X", 196).should == " C4"
+
+          @method.call("% e", 109.52).should == " 1.095200e+02"
+          @method.call("% E", 109.52).should == " 1.095200E+02"
+          @method.call("% f", 10.952).should == " 10.952000"
+          @method.call("% g", 12.1234).should == " 12.1234"
+          @method.call("% G", 12.1234).should == " 12.1234"
+          @method.call("% a", 196).should == " 0x1.88p+7"
+          @method.call("% A", 196).should == " 0X1.88P+7"
         end
 
         it "does not leave a space at the start of negative numbers" do
-          format("% b", -10).should == "-1010"
-          format("% B", -10).should == "-1010"
-          format("% d", -112).should == "-112"
-          format("% i", -112).should == "-112"
-          format("% o", -87).should == "-127"
-          format("% u", -112).should == "-112"
-          format("% x", -196).should == "-c4"
-          format("% X", -196).should == "-C4"
-
-          format("% e", -109.52).should == "-1.095200e+02"
-          format("% E", -109.52).should == "-1.095200E+02"
-          format("% f", -10.952).should == "-10.952000"
-          format("% g", -12.1234).should == "-12.1234"
-          format("% G", -12.1234).should == "-12.1234"
-          format("% a", -196).should == "-0x1.88p+7"
-          format("% A", -196).should == "-0X1.88P+7"
+          @method.call("% b", -10).should == "-1010"
+          @method.call("% B", -10).should == "-1010"
+          @method.call("% d", -112).should == "-112"
+          @method.call("% i", -112).should == "-112"
+          @method.call("% o", -87).should == "-127"
+          @method.call("% u", -112).should == "-112"
+          @method.call("% x", -196).should == "-c4"
+          @method.call("% X", -196).should == "-C4"
+
+          @method.call("% e", -109.52).should == "-1.095200e+02"
+          @method.call("% E", -109.52).should == "-1.095200E+02"
+          @method.call("% f", -10.952).should == "-10.952000"
+          @method.call("% g", -12.1234).should == "-12.1234"
+          @method.call("% G", -12.1234).should == "-12.1234"
+          @method.call("% a", -196).should == "-0x1.88p+7"
+          @method.call("% A", -196).should == "-0X1.88P+7"
         end
 
         it "prevents converting negative argument to two's complement form" do
-          format("% b", -10).should == "-1010"
-          format("% B", -10).should == "-1010"
-          format("% o", -87).should == "-127"
-          format("% x", -196).should == "-c4"
-          format("% X", -196).should == "-C4"
+          @method.call("% b", -10).should == "-1010"
+          @method.call("% B", -10).should == "-1010"
+          @method.call("% o", -87).should == "-127"
+          @method.call("% x", -196).should == "-c4"
+          @method.call("% X", -196).should == "-C4"
         end
 
         it "treats several white spaces as one" do
-          format("%     b", 10).should == " 1010"
-          format("%     B", 10).should == " 1010"
-          format("%     d", 112).should == " 112"
-          format("%     i", 112).should == " 112"
-          format("%     o", 87).should == " 127"
-          format("%     u", 112).should == " 112"
-          format("%     x", 196).should == " c4"
-          format("%     X", 196).should == " C4"
-
-          format("%     e", 109.52).should == " 1.095200e+02"
-          format("%     E", 109.52).should == " 1.095200E+02"
-          format("%     f", 10.952).should == " 10.952000"
-          format("%     g", 12.1234).should == " 12.1234"
-          format("%     G", 12.1234).should == " 12.1234"
-          format("%     a", 196).should == " 0x1.88p+7"
-          format("%     A", 196).should == " 0X1.88P+7"
+          @method.call("%     b", 10).should == " 1010"
+          @method.call("%     B", 10).should == " 1010"
+          @method.call("%     d", 112).should == " 112"
+          @method.call("%     i", 112).should == " 112"
+          @method.call("%     o", 87).should == " 127"
+          @method.call("%     u", 112).should == " 112"
+          @method.call("%     x", 196).should == " c4"
+          @method.call("%     X", 196).should == " C4"
+
+          @method.call("%     e", 109.52).should == " 1.095200e+02"
+          @method.call("%     E", 109.52).should == " 1.095200E+02"
+          @method.call("%     f", 10.952).should == " 10.952000"
+          @method.call("%     g", 12.1234).should == " 12.1234"
+          @method.call("%     G", 12.1234).should == " 12.1234"
+          @method.call("%     a", 196).should == " 0x1.88p+7"
+          @method.call("%     A", 196).should == " 0X1.88P+7"
         end
       end
     end
 
     describe "(digit)$" do
       it "specifies the absolute argument number for this field" do
-        format("%2$b", 0, 10).should == "1010"
-        format("%2$B", 0, 10).should == "1010"
-        format("%2$d", 0, 112).should == "112"
-        format("%2$i", 0, 112).should == "112"
-        format("%2$o", 0, 87).should == "127"
-        format("%2$u", 0, 112).should == "112"
-        format("%2$x", 0, 196).should == "c4"
-        format("%2$X", 0, 196).should == "C4"
-
-        format("%2$e", 0, 109.52).should == "1.095200e+02"
-        format("%2$E", 0, 109.52).should == "1.095200E+02"
-        format("%2$f", 0, 10.952).should == "10.952000"
-        format("%2$g", 0, 12.1234).should == "12.1234"
-        format("%2$G", 0, 12.1234).should == "12.1234"
-        format("%2$a", 0, 196).should == "0x1.88p+7"
-        format("%2$A", 0, 196).should == "0X1.88P+7"
-
-        format("%2$c", 1, 97).should == "a"
-        format("%2$p", "a", []).should == "[]"
-        format("%2$s", "-", "abc").should == "abc"
+        @method.call("%2$b", 0, 10).should == "1010"
+        @method.call("%2$B", 0, 10).should == "1010"
+        @method.call("%2$d", 0, 112).should == "112"
+        @method.call("%2$i", 0, 112).should == "112"
+        @method.call("%2$o", 0, 87).should == "127"
+        @method.call("%2$u", 0, 112).should == "112"
+        @method.call("%2$x", 0, 196).should == "c4"
+        @method.call("%2$X", 0, 196).should == "C4"
+
+        @method.call("%2$e", 0, 109.52).should == "1.095200e+02"
+        @method.call("%2$E", 0, 109.52).should == "1.095200E+02"
+        @method.call("%2$f", 0, 10.952).should == "10.952000"
+        @method.call("%2$g", 0, 12.1234).should == "12.1234"
+        @method.call("%2$G", 0, 12.1234).should == "12.1234"
+        @method.call("%2$a", 0, 196).should == "0x1.88p+7"
+        @method.call("%2$A", 0, 196).should == "0X1.88P+7"
+
+        @method.call("%2$c", 1, 97).should == "a"
+        @method.call("%2$p", "a", []).should == "[]"
+        @method.call("%2$s", "-", "abc").should == "abc"
       end
 
       it "raises exception if argument number is bigger than actual arguments list" do
         -> {
-          format("%4$d", 1, 2, 3)
-        }.should raise_error(ArgumentError)
+          @method.call("%4$d", 1, 2, 3)
+        }.should.raise(ArgumentError)
       end
 
       it "ignores '-' sign" do
-        format("%2$d", 1, 2, 3).should == "2"
-        format("%-2$d", 1, 2, 3).should == "2"
+        @method.call("%2$d", 1, 2, 3).should == "2"
+        @method.call("%-2$d", 1, 2, 3).should == "2"
       end
 
       it "raises ArgumentError exception when absolute and relative argument numbers are mixed" do
         -> {
-          format("%1$d %d", 1, 2)
-        }.should raise_error(ArgumentError)
+          @method.call("%1$d %d", 1, 2)
+        }.should.raise(ArgumentError)
       end
     end
 
     describe "#" do
       context "applies to format o" do
         it "increases the precision until the first digit will be `0' if it is not formatted as complements" do
-          format("%#o", 87).should == "0127"
+          @method.call("%#o", 87).should == "0127"
         end
 
         it "does nothing for negative argument" do
-          format("%#o", -87).should == "..7651"
+          @method.call("%#o", -87).should == "..7651"
         end
       end
 
       context "applies to formats bBxX" do
         it "prefixes the result with 0x, 0X, 0b and 0B respectively for non-zero argument" do
-          format("%#b", 10).should == "0b1010"
-          format("%#b", -10).should == "0b..10110"
-          format("%#B", 10).should == "0B1010"
-          format("%#B", -10).should == "0B..10110"
-
-          format("%#x", 196).should == "0xc4"
-          format("%#x", -196).should == "0x..f3c"
-          format("%#X", 196).should == "0XC4"
-          format("%#X", -196).should == "0X..F3C"
+          @method.call("%#b", 10).should == "0b1010"
+          @method.call("%#b", -10).should == "0b..10110"
+          @method.call("%#B", 10).should == "0B1010"
+          @method.call("%#B", -10).should == "0B..10110"
+
+          @method.call("%#x", 196).should == "0xc4"
+          @method.call("%#x", -196).should == "0x..f3c"
+          @method.call("%#X", 196).should == "0XC4"
+          @method.call("%#X", -196).should == "0X..F3C"
         end
 
         it "does nothing for zero argument" do
-          format("%#b", 0).should == "0"
-          format("%#B", 0).should == "0"
+          @method.call("%#b", 0).should == "0"
+          @method.call("%#B", 0).should == "0"
+
+          @method.call("%#x", 0).should == "0"
+          @method.call("%#X", 0).should == "0"
+        end
+
+        it "does nothing for zero argument when combined with zero precision" do
+          @method.call("%#.0b", 0).should == ""
+          @method.call("%#.0B", 0).should == ""
+
+          @method.call("%#.0x", 0).should == ""
+          @method.call("%#.0X", 0).should == ""
+        end
+      end
 
-          format("%#o", 0).should == "0"
+      context "applies to format o" do
+        it "does nothing for zero argument" do
+          @method.call("%#o", 0).should == "0"
+          @method.call("%#.1o", 0).should == "0"
+        end
 
-          format("%#x", 0).should == "0"
-          format("%#X", 0).should == "0"
+        it "increases the precision if precision zero is requested with zero argument" do
+          @method.call("%#.0o", 0).should == "0"
         end
       end
 
       context "applies to formats aAeEfgG" do
         it "forces a decimal point to be added, even if no digits follow" do
-          format("%#.0a", 16.25).should == "0x1.p+4"
-          format("%#.0A", 16.25).should == "0X1.P+4"
+          @method.call("%#.0a", 16.25).should == "0x1.p+4"
+          @method.call("%#.0A", 16.25).should == "0X1.P+4"
 
-          format("%#.0e", 100).should == "1.e+02"
-          format("%#.0E", 100).should == "1.E+02"
+          @method.call("%#.0e", 100).should == "1.e+02"
+          @method.call("%#.0E", 100).should == "1.E+02"
 
-          format("%#.0f", 123.4).should == "123."
+          @method.call("%#.0f", 123.4).should == "123."
 
-          format("%#g", 123456).should == "123456."
-          format("%#G", 123456).should == "123456."
+          @method.call("%#g", 123456).should == "123456."
+          @method.call("%#G", 123456).should == "123456."
         end
 
         it "changes format from dd.dddd to exponential form for gG" do
-          format("%#.0g", 123.4).should_not == "123."
-          format("%#.0g", 123.4).should == "1.e+02"
+          @method.call("%#.0g", 123.4).should_not == "123."
+          @method.call("%#.0g", 123.4).should == "1.e+02"
         end
       end
 
       context "applies to gG" do
         it "does not remove trailing zeros" do
-          format("%#g", 123.4).should == "123.400"
-          format("%#g", 123.4).should == "123.400"
+          @method.call("%#g", 123.4).should == "123.400"
+          @method.call("%#g", 123.4).should == "123.400"
         end
       end
     end
@@ -544,261 +662,261 @@ describe :kernel_sprintf, shared: true do
     describe "+" do
       context "applies to numeric formats bBdiouxXaAeEfgG" do
         it "adds a leading plus sign to non-negative numbers" do
-          format("%+b", 10).should == "+1010"
-          format("%+B", 10).should == "+1010"
-          format("%+d", 112).should == "+112"
-          format("%+i", 112).should == "+112"
-          format("%+o", 87).should == "+127"
-          format("%+u", 112).should == "+112"
-          format("%+x", 196).should == "+c4"
-          format("%+X", 196).should == "+C4"
-
-          format("%+e", 109.52).should == "+1.095200e+02"
-          format("%+E", 109.52).should == "+1.095200E+02"
-          format("%+f", 10.952).should == "+10.952000"
-          format("%+g", 12.1234).should == "+12.1234"
-          format("%+G", 12.1234).should == "+12.1234"
-          format("%+a", 196).should == "+0x1.88p+7"
-          format("%+A", 196).should == "+0X1.88P+7"
+          @method.call("%+b", 10).should == "+1010"
+          @method.call("%+B", 10).should == "+1010"
+          @method.call("%+d", 112).should == "+112"
+          @method.call("%+i", 112).should == "+112"
+          @method.call("%+o", 87).should == "+127"
+          @method.call("%+u", 112).should == "+112"
+          @method.call("%+x", 196).should == "+c4"
+          @method.call("%+X", 196).should == "+C4"
+
+          @method.call("%+e", 109.52).should == "+1.095200e+02"
+          @method.call("%+E", 109.52).should == "+1.095200E+02"
+          @method.call("%+f", 10.952).should == "+10.952000"
+          @method.call("%+g", 12.1234).should == "+12.1234"
+          @method.call("%+G", 12.1234).should == "+12.1234"
+          @method.call("%+a", 196).should == "+0x1.88p+7"
+          @method.call("%+A", 196).should == "+0X1.88P+7"
         end
 
         it "does not use two's complement form for negative numbers for formats bBoxX" do
-          format("%+b", -10).should == "-1010"
-          format("%+B", -10).should == "-1010"
-          format("%+o", -87).should == "-127"
-          format("%+x", -196).should == "-c4"
-          format("%+X", -196).should == "-C4"
+          @method.call("%+b", -10).should == "-1010"
+          @method.call("%+B", -10).should == "-1010"
+          @method.call("%+o", -87).should == "-127"
+          @method.call("%+x", -196).should == "-c4"
+          @method.call("%+X", -196).should == "-C4"
         end
       end
     end
 
     describe "-" do
       it "left-justifies the result of conversion if width is specified" do
-        format("%-10b", 10).should == "1010      "
-        format("%-10B", 10).should == "1010      "
-        format("%-10d", 112).should == "112       "
-        format("%-10i", 112).should == "112       "
-        format("%-10o", 87).should == "127       "
-        format("%-10u", 112).should == "112       "
-        format("%-10x", 196).should == "c4        "
-        format("%-10X", 196).should == "C4        "
-
-        format("%-20e", 109.52).should == "1.095200e+02        "
-        format("%-20E", 109.52).should == "1.095200E+02        "
-        format("%-20f", 10.952).should == "10.952000           "
-        format("%-20g", 12.1234).should == "12.1234             "
-        format("%-20G", 12.1234).should == "12.1234             "
-        format("%-20a", 196).should == "0x1.88p+7           "
-        format("%-20A", 196).should == "0X1.88P+7           "
-
-        format("%-10c", 97).should == "a         "
-        format("%-10p", []).should == "[]        "
-        format("%-10s", "abc").should == "abc       "
+        @method.call("%-10b", 10).should == "1010      "
+        @method.call("%-10B", 10).should == "1010      "
+        @method.call("%-10d", 112).should == "112       "
+        @method.call("%-10i", 112).should == "112       "
+        @method.call("%-10o", 87).should == "127       "
+        @method.call("%-10u", 112).should == "112       "
+        @method.call("%-10x", 196).should == "c4        "
+        @method.call("%-10X", 196).should == "C4        "
+
+        @method.call("%-20e", 109.52).should == "1.095200e+02        "
+        @method.call("%-20E", 109.52).should == "1.095200E+02        "
+        @method.call("%-20f", 10.952).should == "10.952000           "
+        @method.call("%-20g", 12.1234).should == "12.1234             "
+        @method.call("%-20G", 12.1234).should == "12.1234             "
+        @method.call("%-20a", 196).should == "0x1.88p+7           "
+        @method.call("%-20A", 196).should == "0X1.88P+7           "
+
+        @method.call("%-10c", 97).should == "a         "
+        @method.call("%-10p", []).should == "[]        "
+        @method.call("%-10s", "abc").should == "abc       "
       end
     end
 
     describe "0 (zero)" do
       context "applies to numeric formats bBdiouxXaAeEfgG and width is specified" do
         it "pads with zeros, not spaces" do
-          format("%010b", 10).should == "0000001010"
-          format("%010B", 10).should == "0000001010"
-          format("%010d", 112).should == "0000000112"
-          format("%010i", 112).should == "0000000112"
-          format("%010o", 87).should == "0000000127"
-          format("%010u", 112).should == "0000000112"
-          format("%010x", 196).should == "00000000c4"
-          format("%010X", 196).should == "00000000C4"
-
-          format("%020e", 109.52).should == "000000001.095200e+02"
-          format("%020E", 109.52).should == "000000001.095200E+02"
-          format("%020f", 10.952).should == "0000000000010.952000"
-          format("%020g", 12.1234).should == "000000000000012.1234"
-          format("%020G", 12.1234).should == "000000000000012.1234"
-          format("%020a", 196).should == "0x000000000001.88p+7"
-          format("%020A", 196).should == "0X000000000001.88P+7"
+          @method.call("%010b", 10).should == "0000001010"
+          @method.call("%010B", 10).should == "0000001010"
+          @method.call("%010d", 112).should == "0000000112"
+          @method.call("%010i", 112).should == "0000000112"
+          @method.call("%010o", 87).should == "0000000127"
+          @method.call("%010u", 112).should == "0000000112"
+          @method.call("%010x", 196).should == "00000000c4"
+          @method.call("%010X", 196).should == "00000000C4"
+
+          @method.call("%020e", 109.52).should == "000000001.095200e+02"
+          @method.call("%020E", 109.52).should == "000000001.095200E+02"
+          @method.call("%020f", 10.952).should == "0000000000010.952000"
+          @method.call("%020g", 12.1234).should == "000000000000012.1234"
+          @method.call("%020G", 12.1234).should == "000000000000012.1234"
+          @method.call("%020a", 196).should == "0x000000000001.88p+7"
+          @method.call("%020A", 196).should == "0X000000000001.88P+7"
         end
 
         it "uses radix-1 when displays negative argument as a two's complement" do
-          format("%010b", -10).should == "..11110110"
-          format("%010B", -10).should == "..11110110"
-          format("%010o", -87).should == "..77777651"
-          format("%010x", -196).should == "..ffffff3c"
-          format("%010X", -196).should == "..FFFFFF3C"
+          @method.call("%010b", -10).should == "..11110110"
+          @method.call("%010B", -10).should == "..11110110"
+          @method.call("%010o", -87).should == "..77777651"
+          @method.call("%010x", -196).should == "..ffffff3c"
+          @method.call("%010X", -196).should == "..FFFFFF3C"
         end
       end
     end
 
     describe "*" do
       it "uses the previous argument as the field width" do
-        format("%*b", 10, 10).should == "      1010"
-        format("%*B", 10, 10).should == "      1010"
-        format("%*d", 10, 112).should == "       112"
-        format("%*i", 10, 112).should == "       112"
-        format("%*o", 10, 87).should == "       127"
-        format("%*u", 10, 112).should == "       112"
-        format("%*x", 10, 196).should == "        c4"
-        format("%*X", 10, 196).should == "        C4"
-
-        format("%*e", 20, 109.52).should == "        1.095200e+02"
-        format("%*E", 20, 109.52).should == "        1.095200E+02"
-        format("%*f", 20, 10.952).should == "           10.952000"
-        format("%*g", 20, 12.1234).should == "             12.1234"
-        format("%*G", 20, 12.1234).should == "             12.1234"
-        format("%*a", 20, 196).should == "           0x1.88p+7"
-        format("%*A", 20, 196).should == "           0X1.88P+7"
-
-        format("%*c", 10, 97).should == "         a"
-        format("%*p", 10, []).should == "        []"
-        format("%*s", 10, "abc").should == "       abc"
+        @method.call("%*b", 10, 10).should == "      1010"
+        @method.call("%*B", 10, 10).should == "      1010"
+        @method.call("%*d", 10, 112).should == "       112"
+        @method.call("%*i", 10, 112).should == "       112"
+        @method.call("%*o", 10, 87).should == "       127"
+        @method.call("%*u", 10, 112).should == "       112"
+        @method.call("%*x", 10, 196).should == "        c4"
+        @method.call("%*X", 10, 196).should == "        C4"
+
+        @method.call("%*e", 20, 109.52).should == "        1.095200e+02"
+        @method.call("%*E", 20, 109.52).should == "        1.095200E+02"
+        @method.call("%*f", 20, 10.952).should == "           10.952000"
+        @method.call("%*g", 20, 12.1234).should == "             12.1234"
+        @method.call("%*G", 20, 12.1234).should == "             12.1234"
+        @method.call("%*a", 20, 196).should == "           0x1.88p+7"
+        @method.call("%*A", 20, 196).should == "           0X1.88P+7"
+
+        @method.call("%*c", 10, 97).should == "         a"
+        @method.call("%*p", 10, []).should == "        []"
+        @method.call("%*s", 10, "abc").should == "       abc"
       end
 
       it "left-justifies the result if width is negative" do
-        format("%*b", -10, 10).should == "1010      "
-        format("%*B", -10, 10).should == "1010      "
-        format("%*d", -10, 112).should == "112       "
-        format("%*i", -10, 112).should == "112       "
-        format("%*o", -10, 87).should == "127       "
-        format("%*u", -10, 112).should == "112       "
-        format("%*x", -10, 196).should == "c4        "
-        format("%*X", -10, 196).should == "C4        "
-
-        format("%*e", -20, 109.52).should == "1.095200e+02        "
-        format("%*E", -20, 109.52).should == "1.095200E+02        "
-        format("%*f", -20, 10.952).should == "10.952000           "
-        format("%*g", -20, 12.1234).should == "12.1234             "
-        format("%*G", -20, 12.1234).should == "12.1234             "
-        format("%*a", -20, 196).should == "0x1.88p+7           "
-        format("%*A", -20, 196).should == "0X1.88P+7           "
-
-        format("%*c", -10, 97).should == "a         "
-        format("%*p", -10, []).should == "[]        "
-        format("%*s", -10, "abc").should == "abc       "
+        @method.call("%*b", -10, 10).should == "1010      "
+        @method.call("%*B", -10, 10).should == "1010      "
+        @method.call("%*d", -10, 112).should == "112       "
+        @method.call("%*i", -10, 112).should == "112       "
+        @method.call("%*o", -10, 87).should == "127       "
+        @method.call("%*u", -10, 112).should == "112       "
+        @method.call("%*x", -10, 196).should == "c4        "
+        @method.call("%*X", -10, 196).should == "C4        "
+
+        @method.call("%*e", -20, 109.52).should == "1.095200e+02        "
+        @method.call("%*E", -20, 109.52).should == "1.095200E+02        "
+        @method.call("%*f", -20, 10.952).should == "10.952000           "
+        @method.call("%*g", -20, 12.1234).should == "12.1234             "
+        @method.call("%*G", -20, 12.1234).should == "12.1234             "
+        @method.call("%*a", -20, 196).should == "0x1.88p+7           "
+        @method.call("%*A", -20, 196).should == "0X1.88P+7           "
+
+        @method.call("%*c", -10, 97).should == "a         "
+        @method.call("%*p", -10, []).should == "[]        "
+        @method.call("%*s", -10, "abc").should == "abc       "
       end
 
       it "uses the specified argument as the width if * is followed by a number and $" do
-        format("%1$*2$b", 10, 10).should == "      1010"
-        format("%1$*2$B", 10, 10).should == "      1010"
-        format("%1$*2$d", 112, 10).should == "       112"
-        format("%1$*2$i", 112, 10).should == "       112"
-        format("%1$*2$o", 87, 10).should == "       127"
-        format("%1$*2$u", 112, 10).should == "       112"
-        format("%1$*2$x", 196, 10).should == "        c4"
-        format("%1$*2$X", 196, 10).should == "        C4"
-
-        format("%1$*2$e", 109.52, 20).should == "        1.095200e+02"
-        format("%1$*2$E", 109.52, 20).should == "        1.095200E+02"
-        format("%1$*2$f", 10.952, 20).should == "           10.952000"
-        format("%1$*2$g", 12.1234, 20).should == "             12.1234"
-        format("%1$*2$G", 12.1234, 20).should == "             12.1234"
-        format("%1$*2$a", 196, 20).should == "           0x1.88p+7"
-        format("%1$*2$A", 196, 20).should == "           0X1.88P+7"
-
-        format("%1$*2$c", 97, 10).should == "         a"
-        format("%1$*2$p", [], 10).should == "        []"
-        format("%1$*2$s", "abc", 10).should == "       abc"
+        @method.call("%1$*2$b", 10, 10).should == "      1010"
+        @method.call("%1$*2$B", 10, 10).should == "      1010"
+        @method.call("%1$*2$d", 112, 10).should == "       112"
+        @method.call("%1$*2$i", 112, 10).should == "       112"
+        @method.call("%1$*2$o", 87, 10).should == "       127"
+        @method.call("%1$*2$u", 112, 10).should == "       112"
+        @method.call("%1$*2$x", 196, 10).should == "        c4"
+        @method.call("%1$*2$X", 196, 10).should == "        C4"
+
+        @method.call("%1$*2$e", 109.52, 20).should == "        1.095200e+02"
+        @method.call("%1$*2$E", 109.52, 20).should == "        1.095200E+02"
+        @method.call("%1$*2$f", 10.952, 20).should == "           10.952000"
+        @method.call("%1$*2$g", 12.1234, 20).should == "             12.1234"
+        @method.call("%1$*2$G", 12.1234, 20).should == "             12.1234"
+        @method.call("%1$*2$a", 196, 20).should == "           0x1.88p+7"
+        @method.call("%1$*2$A", 196, 20).should == "           0X1.88P+7"
+
+        @method.call("%1$*2$c", 97, 10).should == "         a"
+        @method.call("%1$*2$p", [], 10).should == "        []"
+        @method.call("%1$*2$s", "abc", 10).should == "       abc"
       end
 
       it "left-justifies the result if specified with $ argument is negative" do
-        format("%1$*2$b", 10, -10).should == "1010      "
-        format("%1$*2$B", 10, -10).should == "1010      "
-        format("%1$*2$d", 112, -10).should == "112       "
-        format("%1$*2$i", 112, -10).should == "112       "
-        format("%1$*2$o", 87, -10).should == "127       "
-        format("%1$*2$u", 112, -10).should == "112       "
-        format("%1$*2$x", 196, -10).should == "c4        "
-        format("%1$*2$X", 196, -10).should == "C4        "
-
-        format("%1$*2$e", 109.52, -20).should == "1.095200e+02        "
-        format("%1$*2$E", 109.52, -20).should == "1.095200E+02        "
-        format("%1$*2$f", 10.952, -20).should == "10.952000           "
-        format("%1$*2$g", 12.1234, -20).should == "12.1234             "
-        format("%1$*2$G", 12.1234, -20).should == "12.1234             "
-        format("%1$*2$a", 196, -20).should == "0x1.88p+7           "
-        format("%1$*2$A", 196, -20).should == "0X1.88P+7           "
-
-        format("%1$*2$c", 97, -10).should == "a         "
-        format("%1$*2$p", [], -10).should == "[]        "
-        format("%1$*2$s", "abc", -10).should == "abc       "
+        @method.call("%1$*2$b", 10, -10).should == "1010      "
+        @method.call("%1$*2$B", 10, -10).should == "1010      "
+        @method.call("%1$*2$d", 112, -10).should == "112       "
+        @method.call("%1$*2$i", 112, -10).should == "112       "
+        @method.call("%1$*2$o", 87, -10).should == "127       "
+        @method.call("%1$*2$u", 112, -10).should == "112       "
+        @method.call("%1$*2$x", 196, -10).should == "c4        "
+        @method.call("%1$*2$X", 196, -10).should == "C4        "
+
+        @method.call("%1$*2$e", 109.52, -20).should == "1.095200e+02        "
+        @method.call("%1$*2$E", 109.52, -20).should == "1.095200E+02        "
+        @method.call("%1$*2$f", 10.952, -20).should == "10.952000           "
+        @method.call("%1$*2$g", 12.1234, -20).should == "12.1234             "
+        @method.call("%1$*2$G", 12.1234, -20).should == "12.1234             "
+        @method.call("%1$*2$a", 196, -20).should == "0x1.88p+7           "
+        @method.call("%1$*2$A", 196, -20).should == "0X1.88P+7           "
+
+        @method.call("%1$*2$c", 97, -10).should == "a         "
+        @method.call("%1$*2$p", [], -10).should == "[]        "
+        @method.call("%1$*2$s", "abc", -10).should == "abc       "
       end
 
       it "raises ArgumentError when is mixed with width" do
         -> {
-          format("%*10d", 10, 112)
-        }.should raise_error(ArgumentError)
+          @method.call("%*10d", 10, 112)
+        }.should.raise(ArgumentError)
       end
     end
   end
 
   describe "width" do
     it "specifies the minimum number of characters that will be written to the result" do
-      format("%10b", 10).should == "      1010"
-      format("%10B", 10).should == "      1010"
-      format("%10d", 112).should == "       112"
-      format("%10i", 112).should == "       112"
-      format("%10o", 87).should == "       127"
-      format("%10u", 112).should == "       112"
-      format("%10x", 196).should == "        c4"
-      format("%10X", 196).should == "        C4"
-
-      format("%20e", 109.52).should == "        1.095200e+02"
-      format("%20E", 109.52).should == "        1.095200E+02"
-      format("%20f", 10.952).should == "           10.952000"
-      format("%20g", 12.1234).should == "             12.1234"
-      format("%20G", 12.1234).should == "             12.1234"
-      format("%20a", 196).should == "           0x1.88p+7"
-      format("%20A", 196).should == "           0X1.88P+7"
-
-      format("%10c", 97).should == "         a"
-      format("%10p", []).should == "        []"
-      format("%10s", "abc").should == "       abc"
+      @method.call("%10b", 10).should == "      1010"
+      @method.call("%10B", 10).should == "      1010"
+      @method.call("%10d", 112).should == "       112"
+      @method.call("%10i", 112).should == "       112"
+      @method.call("%10o", 87).should == "       127"
+      @method.call("%10u", 112).should == "       112"
+      @method.call("%10x", 196).should == "        c4"
+      @method.call("%10X", 196).should == "        C4"
+
+      @method.call("%20e", 109.52).should == "        1.095200e+02"
+      @method.call("%20E", 109.52).should == "        1.095200E+02"
+      @method.call("%20f", 10.952).should == "           10.952000"
+      @method.call("%20g", 12.1234).should == "             12.1234"
+      @method.call("%20G", 12.1234).should == "             12.1234"
+      @method.call("%20a", 196).should == "           0x1.88p+7"
+      @method.call("%20A", 196).should == "           0X1.88P+7"
+
+      @method.call("%10c", 97).should == "         a"
+      @method.call("%10p", []).should == "        []"
+      @method.call("%10s", "abc").should == "       abc"
     end
 
     it "is ignored if argument's actual length is greater" do
-      format("%5d", 1234567890).should == "1234567890"
+      @method.call("%5d", 1234567890).should == "1234567890"
     end
   end
 
   describe "precision" do
     context "integer types" do
       it "controls the number of decimal places displayed" do
-        format("%.6b", 10).should == "001010"
-        format("%.6B", 10).should == "001010"
-        format("%.5d", 112).should == "00112"
-        format("%.5i", 112).should == "00112"
-        format("%.5o", 87).should == "00127"
-        format("%.5u", 112).should == "00112"
+        @method.call("%.6b", 10).should == "001010"
+        @method.call("%.6B", 10).should == "001010"
+        @method.call("%.5d", 112).should == "00112"
+        @method.call("%.5i", 112).should == "00112"
+        @method.call("%.5o", 87).should == "00127"
+        @method.call("%.5u", 112).should == "00112"
 
-        format("%.5x", 196).should == "000c4"
-        format("%.5X", 196).should == "000C4"
+        @method.call("%.5x", 196).should == "000c4"
+        @method.call("%.5X", 196).should == "000C4"
       end
     end
 
     context "float types" do
       it "controls the number of decimal places displayed in fraction part" do
-        format("%.10e", 109.52).should == "1.0952000000e+02"
-        format("%.10E", 109.52).should == "1.0952000000E+02"
-        format("%.10f", 10.952).should == "10.9520000000"
-        format("%.10a", 196).should == "0x1.8800000000p+7"
-        format("%.10A", 196).should == "0X1.8800000000P+7"
+        @method.call("%.10e", 109.52).should == "1.0952000000e+02"
+        @method.call("%.10E", 109.52).should == "1.0952000000E+02"
+        @method.call("%.10f", 10.952).should == "10.9520000000"
+        @method.call("%.10a", 196).should == "0x1.8800000000p+7"
+        @method.call("%.10A", 196).should == "0X1.8800000000P+7"
       end
 
       it "does not affect G format" do
-        format("%.10g", 12.1234).should == "12.1234"
-        format("%.10g", 123456789).should == "123456789"
+        @method.call("%.10g", 12.1234).should == "12.1234"
+        @method.call("%.10g", 123456789).should == "123456789"
       end
     end
 
     context "string formats" do
       it "determines the maximum number of characters to be copied from the string" do
-        format("%.1p", [1]).should == "["
-        format("%.2p", [1]).should == "[1"
-        format("%.10p", [1]).should == "[1]"
-        format("%.0p", [1]).should == ""
+        @method.call("%.1p", [1]).should == "["
+        @method.call("%.2p", [1]).should == "[1"
+        @method.call("%.10p", [1]).should == "[1]"
+        @method.call("%.0p", [1]).should == ""
 
-        format("%.1s", "abc").should == "a"
-        format("%.2s", "abc").should == "ab"
-        format("%.10s", "abc").should == "abc"
-        format("%.0s", "abc").should == ""
+        @method.call("%.1s", "abc").should == "a"
+        @method.call("%.2s", "abc").should == "ab"
+        @method.call("%.10s", "abc").should == "abc"
+        @method.call("%.0s", "abc").should == ""
       end
     end
   end
@@ -806,50 +924,67 @@ describe :kernel_sprintf, shared: true do
   describe "reference by name" do
     describe "%<name>s style" do
       it "uses value passed in a hash argument" do
-        format("%<foo>d", foo: 123).should == "123"
+        @method.call("%<foo>d", foo: 123).should == "123"
       end
 
       it "supports flags, width, precision and type" do
-        format("%+20.10<foo>f", foo: 10.952).should == "      +10.9520000000"
+        @method.call("%+20.10<foo>f", foo: 10.952).should == "      +10.9520000000"
       end
 
       it "allows to place name in any position" do
-        format("%+15.5<foo>f", foo: 10.952).should == "      +10.95200"
-        format("%+15<foo>.5f", foo: 10.952).should == "      +10.95200"
-        format("%+<foo>15.5f", foo: 10.952).should == "      +10.95200"
-        format("%<foo>+15.5f", foo: 10.952).should == "      +10.95200"
+        @method.call("%+15.5<foo>f", foo: 10.952).should == "      +10.95200"
+        @method.call("%+15<foo>.5f", foo: 10.952).should == "      +10.95200"
+        @method.call("%+<foo>15.5f", foo: 10.952).should == "      +10.95200"
+        @method.call("%<foo>+15.5f", foo: 10.952).should == "      +10.95200"
       end
 
       it "cannot be mixed with unnamed style" do
         -> {
-          format("%d %<foo>d", 1, foo: "123")
-        }.should raise_error(ArgumentError)
+          @method.call("%d %<foo>d", 1, foo: "123")
+        }.should.raise(ArgumentError)
       end
     end
 
     describe "%{name} style" do
       it "uses value passed in a hash argument" do
-        format("%{foo}", foo: 123).should == "123"
+        @method.call("%{foo}", foo: 123).should == "123"
       end
 
       it "does not support type style" do
-        format("%{foo}d", foo: 123).should == "123d"
+        @method.call("%{foo}d", foo: 123).should == "123d"
       end
 
       it "supports flags, width and precision" do
-        format("%-20.5{foo}", foo: "123456789").should == "12345               "
+        @method.call("%-20.5{foo}", foo: "123456789").should == "12345               "
       end
 
       it "cannot be mixed with unnamed style" do
         -> {
-          format("%d %{foo}", 1, foo: "123")
-        }.should raise_error(ArgumentError)
+          @method.call("%d %{foo}", 1, foo: "123")
+        }.should.raise(ArgumentError)
       end
 
-      it "raises KeyError when there is no matching key" do
+      it "respects Hash#default when there is no set key" do
+        @method.call("%{foo}", Hash.new(123)).should == "123"
+        @method.call("%{foo}", Hash.new { 123 }).should == "123"
+      end
+
+      it "raises KeyError when Hash#default returns nil" do
+        -> {
+          @method.call("%{foo}", {})
+        }.should.raise(KeyError, 'key{foo} not found')
+
+        -> {
+          @method.call("%{foo}", Hash.new(nil))
+        }.should.raise(KeyError, 'key{foo} not found')
+
         -> {
-          format("%{foo}", {})
-        }.should raise_error(KeyError)
+          @method.call("%{foo}", Hash.new { nil })
+        }.should.raise(KeyError, 'key{foo} not found')
+      end
+
+      it "accepts a nil value for an existing key" do
+        @method.call("%{foo}", { foo: nil }).should == ""
       end
 
       it "converts value to String with to_s" do
@@ -860,18 +995,40 @@ describe :kernel_sprintf, shared: true do
         obj.should_receive(:to_s).and_return("42")
         obj.should_not_receive(:to_str)
 
-        format("%{foo}", foo: obj).should == "42"
+        @method.call("%{foo}", foo: obj).should == "42"
       end
     end
   end
 
   describe "faulty key" do
-    before :all do
-      @base_method = @method
+    before :each do
+      @object = { foooo: 1 }
+    end
+
+    it "raises a KeyError" do
+      -> {
+        @method.call("%<foo>s", @object)
+      }.should.raise(KeyError)
+    end
+
+    it "sets the Hash as the receiver of KeyError" do
+      -> {
+        @method.call("%<foo>s", @object)
+      }.should.raise(KeyError) { |err|
+        err.receiver.should.equal?(@object)
+      }
+    end
+
+    it "sets the unmatched key as the key of KeyError" do
+      -> {
+        @method.call("%<foo>s", @object)
+      }.should.raise(KeyError) { |err|
+        err.key.to_s.should == 'foo'
+      }
     end
+  end
 
-    it_behaves_like :key_error, -> obj, key {
-      @base_method.call("%<#{key}>s", obj)
-    }, { foooo: 1 }
+  it "does not raise error when passed more arguments than needed" do
+    sprintf("%s %d %c", "string", 2, "c", []).should == "string 2 c"
   end
 end
diff --git a/spec/ruby/core/kernel/shared/sprintf_encoding.rb b/spec/ruby/core/kernel/shared/sprintf_encoding.rb
index c3d62bf3bb..849c95cbb7 100644
--- a/spec/ruby/core/kernel/shared/sprintf_encoding.rb
+++ b/spec/ruby/core/kernel/shared/sprintf_encoding.rb
@@ -1,28 +1,67 @@
+# Keep encoding-related specs in a separate shared example to be able to skip them in IO/File/StringIO specs.
+# It's difficult to check result's encoding in the test after writing to a file/io buffer.
 describe :kernel_sprintf_encoding, shared: true do
-  def format(*args)
-    @method.call(*args)
+  it "can produce a string with valid encoding" do
+    string = @method.call("good day %{valid}", valid: "e")
+    string.encoding.should == Encoding::UTF_8
+    string.valid_encoding?.should == true
+  end
+
+  it "can produce a string with invalid encoding" do
+    string = @method.call("good day %{invalid}", invalid: "\x80")
+    string.encoding.should == Encoding::UTF_8
+    string.valid_encoding?.should == false
   end
 
   it "returns a String in the same encoding as the format String if compatible" do
-    string = "%s".force_encoding(Encoding::KOI8_U)
-    result = format(string, "dogs")
-    result.encoding.should equal(Encoding::KOI8_U)
+    string = "%s".dup.force_encoding(Encoding::KOI8_U)
+    result = @method.call(string, "dogs")
+    result.encoding.should.equal?(Encoding::KOI8_U)
   end
 
   it "returns a String in the argument's encoding if format encoding is more restrictive" do
-    string = "foo %s".force_encoding(Encoding::US_ASCII)
-    argument = "b\303\274r".force_encoding(Encoding::UTF_8)
+    string = "foo %s".dup.force_encoding(Encoding::US_ASCII)
+    argument = "b\303\274r".dup.force_encoding(Encoding::UTF_8)
 
-    result = format(string, argument)
-    result.encoding.should equal(Encoding::UTF_8)
+    result = @method.call(string, argument)
+    result.encoding.should.equal?(Encoding::UTF_8)
   end
 
-  it "raises Encoding::CompatibilityError if both encodings are ASCII compatible and there ano not ASCII characters" do
+  it "raises Encoding::CompatibilityError if both encodings are ASCII compatible and there are not ASCII characters" do
     string = "Ä %s".encode('windows-1252')
     argument = "Ђ".encode('windows-1251')
 
     -> {
-      format(string, argument)
-    }.should raise_error(Encoding::CompatibilityError)
+      @method.call(string, argument)
+    }.should.raise(Encoding::CompatibilityError)
+  end
+
+  describe "%c" do
+    it "supports Unicode characters" do
+      result = @method.call("%c", 1286)
+      result.should == "Ԇ"
+      result.bytes.should == [212, 134]
+
+      result = @method.call("%c", "ش")
+      result.should == "ش"
+      result.bytes.should == [216, 180]
+    end
+
+    it "raises error when a codepoint isn't representable in an encoding of a format string" do
+      format = "%c".encode("ASCII")
+
+      -> {
+        @method.call(format, 1286)
+      }.should.raise(RangeError, /out of char range/)
+    end
+
+    it "uses the encoding of the format string to interpret codepoints" do
+      format = "%c".dup.force_encoding("euc-jp")
+      result = @method.call(format, 9415601)
+
+      result.encoding.should == Encoding::EUC_JP
+      result.should == "é".encode(Encoding::EUC_JP)
+      result.bytes.should == [143, 171, 177]
+    end
   end
 end
diff --git a/spec/ruby/core/kernel/shared/then.rb b/spec/ruby/core/kernel/shared/then.rb
index b52075371f..c71393bf50 100644
--- a/spec/ruby/core/kernel/shared/then.rb
+++ b/spec/ruby/core/kernel/shared/then.rb
@@ -1,20 +1,20 @@
 describe :kernel_then, shared: true do
   it "yields self" do
     object = Object.new
-    object.send(@method) { |o| o.should equal object }
+    object.send(@method) { |o| o.should.equal? object }
   end
 
   it "returns the block return value" do
     object = Object.new
-    object.send(@method) { 42 }.should equal 42
+    object.send(@method) { 42 }.should.equal? 42
   end
 
   it "returns a sized Enumerator when no block given" do
     object = Object.new
     enum = object.send(@method)
-    enum.should be_an_instance_of Enumerator
-    enum.size.should equal 1
-    enum.peek.should equal object
-    enum.first.should equal object
+    enum.should.instance_of? Enumerator
+    enum.size.should.equal? 1
+    enum.peek.should.equal? object
+    enum.first.should.equal? object
   end
 end
diff --git a/spec/ruby/core/kernel/singleton_class_spec.rb b/spec/ruby/core/kernel/singleton_class_spec.rb
index 5dbb4f8c05..7915272937 100644
--- a/spec/ruby/core/kernel/singleton_class_spec.rb
+++ b/spec/ruby/core/kernel/singleton_class_spec.rb
@@ -1,3 +1,6 @@
+# truffleruby_primitives: true
+require_relative '../../spec_helper'
+
 describe "Kernel#singleton_class" do
   it "returns class extended from an object" do
     x = Object.new
@@ -17,11 +20,55 @@ describe "Kernel#singleton_class" do
     false.singleton_class.should == FalseClass
   end
 
-  it "raises TypeError for Fixnum" do
-    -> { 123.singleton_class }.should raise_error(TypeError)
+  it "raises TypeError for Integer" do
+    -> { 123.singleton_class }.should.raise(TypeError, "can't define singleton")
+  end
+
+  it "raises TypeError for Float" do
+    -> { 3.14.singleton_class }.should.raise(TypeError, "can't define singleton")
   end
 
   it "raises TypeError for Symbol" do
-    -> { :foo.singleton_class }.should raise_error(TypeError)
+    -> { :foo.singleton_class }.should.raise(TypeError, "can't define singleton")
+  end
+
+  it "raises TypeError for a frozen deduplicated String" do
+    -> { (-"string").singleton_class }.should.raise(TypeError, "can't define singleton")
+    -> { a = -"string"; a.singleton_class }.should.raise(TypeError, "can't define singleton")
+    -> { a = "string"; (-a).singleton_class }.should.raise(TypeError, "can't define singleton")
+  end
+
+  it "returns a frozen singleton class if object is frozen" do
+    obj = Object.new
+    obj.freeze
+    obj.singleton_class.frozen?.should == true
+  end
+
+  context "for an IO object with a replaced singleton class" do
+    it "looks up singleton methods from the fresh singleton class after an object instance got a new one" do
+      proxy = -> io { io.foo }
+      if RUBY_ENGINE == 'truffleruby'
+        # We need an inline cache with only this object seen, the best way to do that is to use a Primitive
+        sclass = -> io { Primitive.singleton_class(io) }
+      else
+        sclass = -> io { io.singleton_class }
+      end
+
+      io = File.new(__FILE__)
+      io.define_singleton_method(:foo) { "old" }
+      sclass1 = sclass.call(io)
+      proxy.call(io).should == "old"
+
+      # IO#reopen is the only method which can replace an object's singleton class
+      io2 = File.new(__FILE__)
+      io.reopen(io2)
+      io.define_singleton_method(:foo) { "new" }
+      sclass2 = sclass.call(io)
+      sclass2.should_not.equal?(sclass1)
+      proxy.call(io).should == "new"
+    ensure
+      io2.close
+      io.close
+    end
   end
 end
diff --git a/spec/ruby/core/kernel/singleton_method_spec.rb b/spec/ruby/core/kernel/singleton_method_spec.rb
index 0bdf125ad8..fe8e23eb02 100644
--- a/spec/ruby/core/kernel/singleton_method_spec.rb
+++ b/spec/ruby/core/kernel/singleton_method_spec.rb
@@ -1,10 +1,10 @@
 require_relative '../../spec_helper'
 
 describe "Kernel#singleton_method" do
-  it "find a method defined on the singleton class" do
+  it "finds a method defined on the singleton class" do
     obj = Object.new
     def obj.foo; end
-    obj.singleton_method(:foo).should be_an_instance_of(Method)
+    obj.singleton_method(:foo).should.instance_of?(Method)
   end
 
   it "returns a Method which can be called" do
@@ -23,7 +23,7 @@ describe "Kernel#singleton_method" do
     obj.foo.should == 42
     -> {
       obj.singleton_method(:foo)
-    }.should raise_error(NameError) { |e|
+    }.should.raise(NameError) { |e|
       # a NameError and not a NoMethodError
       e.class.should == NameError
     }
@@ -33,9 +33,53 @@ describe "Kernel#singleton_method" do
     obj = Object.new
     -> {
       obj.singleton_method(:not_existing)
-    }.should raise_error(NameError) { |e|
+    }.should.raise(NameError) { |e|
       # a NameError and not a NoMethodError
       e.class.should == NameError
     }
   end
+
+  ruby_bug "#20620", ""..."3.4" do
+    it "finds a method defined in a module included in the singleton class" do
+      m = Module.new do
+        def foo
+          :foo
+        end
+      end
+
+      obj = Object.new
+      obj.singleton_class.include(m)
+
+      obj.singleton_method(:foo).should.instance_of?(Method)
+      obj.singleton_method(:foo).call.should == :foo
+    end
+
+    it "finds a method defined in a module prepended in the singleton class" do
+      m = Module.new do
+        def foo
+          :foo
+        end
+      end
+
+      obj = Object.new
+      obj.singleton_class.prepend(m)
+
+      obj.singleton_method(:foo).should.instance_of?(Method)
+      obj.singleton_method(:foo).call.should == :foo
+    end
+
+    it "finds a method defined in a module that an object is extended with" do
+      m = Module.new do
+        def foo
+          :foo
+        end
+      end
+
+      obj = Object.new
+      obj.extend(m)
+
+      obj.singleton_method(:foo).should.instance_of?(Method)
+      obj.singleton_method(:foo).call.should == :foo
+    end
+  end
 end
diff --git a/spec/ruby/core/kernel/singleton_methods_spec.rb b/spec/ruby/core/kernel/singleton_methods_spec.rb
index eb4cede110..a7f6969519 100644
--- a/spec/ruby/core/kernel/singleton_methods_spec.rb
+++ b/spec/ruby/core/kernel/singleton_methods_spec.rb
@@ -8,33 +8,33 @@ describe :kernel_singleton_methods, shared: true do
   end
 
   it "returns the names of module methods for a module" do
-    ReflectSpecs::M.singleton_methods(*@object).should include(:ms_pro, :ms_pub)
+    ReflectSpecs::M.singleton_methods(*@object).to_set.should >= Set[:ms_pro, :ms_pub]
   end
 
   it "does not return private module methods for a module" do
-    ReflectSpecs::M.singleton_methods(*@object).should_not include(:ms_pri)
+    ReflectSpecs::M.singleton_methods(*@object).should_not.include?(:ms_pri)
   end
 
   it "returns the names of class methods for a class" do
-    ReflectSpecs::A.singleton_methods(*@object).should include(:as_pro, :as_pub)
+    ReflectSpecs::A.singleton_methods(*@object).to_set.should >= Set[:as_pro, :as_pub]
   end
 
   it "does not return private class methods for a class" do
-    ReflectSpecs::A.singleton_methods(*@object).should_not include(:as_pri)
+    ReflectSpecs::A.singleton_methods(*@object).should_not.include?(:as_pri)
   end
 
   it "returns the names of singleton methods for an object" do
-    ReflectSpecs.os.singleton_methods(*@object).should include(:os_pro, :os_pub)
+    ReflectSpecs.os.singleton_methods(*@object).to_set.should >= Set[:os_pro, :os_pub]
   end
 end
 
 describe :kernel_singleton_methods_modules, shared: true do
   it "does not return any included methods for a module including a module" do
-    ReflectSpecs::N.singleton_methods(*@object).should include(:ns_pro, :ns_pub)
+    ReflectSpecs::N.singleton_methods(*@object).to_set.should >= Set[:ns_pro, :ns_pub]
   end
 
   it "does not return any included methods for a class including a module" do
-    ReflectSpecs::D.singleton_methods(*@object).should include(:ds_pro, :ds_pub)
+    ReflectSpecs::D.singleton_methods(*@object).to_set.should >= Set[:ds_pro, :ds_pub]
   end
 
   it "for a module does not return methods in a module prepended to Module itself" do
@@ -44,7 +44,7 @@ describe :kernel_singleton_methods_modules, shared: true do
 
     ancestors = mod.singleton_class.ancestors
     ancestors[0...2].should == [ mod.singleton_class, mod ]
-    ancestors.should include(SingletonMethodsSpecs::Prepended)
+    ancestors.should.include?(SingletonMethodsSpecs::Prepended)
 
     # Do not search prepended modules of `Module`, as that's a non-singleton class
     mod.singleton_methods.should == []
@@ -52,8 +52,8 @@ describe :kernel_singleton_methods_modules, shared: true do
 end
 
 describe :kernel_singleton_methods_supers, shared: true do
-  it "returns the names of singleton methods for an object extented with a module" do
-    ReflectSpecs.oe.singleton_methods(*@object).should include(:m_pro, :m_pub)
+  it "returns the names of singleton methods for an object extended with a module" do
+    ReflectSpecs.oe.singleton_methods(*@object).to_set.should >= Set[:m_pro, :m_pub]
   end
 
   it "returns a unique list for an object extended with a module" do
@@ -62,16 +62,16 @@ describe :kernel_singleton_methods_supers, shared: true do
     r.should == [:pro, :pub]
   end
 
-  it "returns the names of singleton methods for an object extented with two modules" do
-    ReflectSpecs.oee.singleton_methods(*@object).should include(:m_pro, :m_pub, :n_pro, :n_pub)
+  it "returns the names of singleton methods for an object extended with two modules" do
+    ReflectSpecs.oee.singleton_methods(*@object).to_set.should >= Set[:m_pro, :m_pub, :n_pro, :n_pub]
   end
 
-  it "returns the names of singleton methods for an object extented with a module including a module" do
-    ReflectSpecs.oei.singleton_methods(*@object).should include(:n_pro, :n_pub, :m_pro, :m_pub)
+  it "returns the names of singleton methods for an object extended with a module including a module" do
+    ReflectSpecs.oei.singleton_methods(*@object).to_set.should >= Set[:n_pro, :n_pub, :m_pro, :m_pub]
   end
 
   it "returns the names of inherited singleton methods for a subclass" do
-    ReflectSpecs::B.singleton_methods(*@object).should include(:as_pro, :as_pub, :bs_pro, :bs_pub)
+    ReflectSpecs::B.singleton_methods(*@object).to_set.should >= Set[:as_pro, :as_pub, :bs_pro, :bs_pub]
   end
 
   it "returns a unique list for a subclass" do
@@ -81,7 +81,7 @@ describe :kernel_singleton_methods_supers, shared: true do
   end
 
   it "returns the names of inherited singleton methods for a subclass including a module" do
-    ReflectSpecs::C.singleton_methods(*@object).should include(:as_pro, :as_pub, :cs_pro, :cs_pub)
+    ReflectSpecs::C.singleton_methods(*@object).to_set.should >= Set[:as_pro, :as_pub, :cs_pro, :cs_pub]
   end
 
   it "returns a unique list for a subclass including a module" do
@@ -91,57 +91,62 @@ describe :kernel_singleton_methods_supers, shared: true do
   end
 
   it "returns the names of inherited singleton methods for a subclass of a class including a module" do
-    ReflectSpecs::E.singleton_methods(*@object).should include(:ds_pro, :ds_pub, :es_pro, :es_pub)
+    ReflectSpecs::E.singleton_methods(*@object).to_set.should >= Set[:ds_pro, :ds_pub, :es_pro, :es_pub]
   end
 
   it "returns the names of inherited singleton methods for a subclass of a class that includes a module, where the subclass also includes a module" do
-    ReflectSpecs::F.singleton_methods(*@object).should include(:ds_pro, :ds_pub, :fs_pro, :fs_pub)
+    ReflectSpecs::F.singleton_methods(*@object).to_set.should >= Set[:ds_pro, :ds_pub, :fs_pro, :fs_pub]
   end
 
   it "returns the names of inherited singleton methods for a class extended with a module" do
-    ReflectSpecs::P.singleton_methods(*@object).should include(:m_pro, :m_pub)
+    ReflectSpecs::P.singleton_methods(*@object).to_set.should >= Set[:m_pro, :m_pub]
   end
 end
 
 describe :kernel_singleton_methods_private_supers, shared: true do
   it "does not return private singleton methods for an object extended with a module" do
-    ReflectSpecs.oe.singleton_methods(*@object).should_not include(:m_pri)
+    ReflectSpecs.oe.singleton_methods(*@object).should_not.include?(:m_pri)
   end
 
   it "does not return private singleton methods for an object extended with two modules" do
-    ReflectSpecs.oee.singleton_methods(*@object).should_not include(:m_pri)
+    ReflectSpecs.oee.singleton_methods(*@object).should_not.include?(:m_pri)
   end
 
-  it "does not return private singleton methods for an object extented with a module including a module" do
-    ReflectSpecs.oei.singleton_methods(*@object).should_not include(:n_pri, :m_pri)
+  it "does not return private singleton methods for an object extended with a module including a module" do
+    ReflectSpecs.oei.singleton_methods(*@object).should_not.include?(:n_pri)
+    ReflectSpecs.oei.singleton_methods(*@object).should_not.include?(:m_pri)
   end
 
   it "does not return private singleton methods for a class extended with a module" do
-    ReflectSpecs::P.singleton_methods(*@object).should_not include(:m_pri)
+    ReflectSpecs::P.singleton_methods(*@object).should_not.include?(:m_pri)
   end
 
   it "does not return private inherited singleton methods for a module including a module" do
-    ReflectSpecs::N.singleton_methods(*@object).should_not include(:ns_pri)
+    ReflectSpecs::N.singleton_methods(*@object).should_not.include?(:ns_pri)
   end
 
   it "does not return private inherited singleton methods for a class including a module" do
-    ReflectSpecs::D.singleton_methods(*@object).should_not include(:ds_pri)
+    ReflectSpecs::D.singleton_methods(*@object).should_not.include?(:ds_pri)
   end
 
   it "does not return private inherited singleton methods for a subclass" do
-    ReflectSpecs::B.singleton_methods(*@object).should_not include(:as_pri, :bs_pri)
+    ReflectSpecs::B.singleton_methods(*@object).should_not.include?(:as_pri)
+    ReflectSpecs::B.singleton_methods(*@object).should_not.include?(:bs_pri)
   end
 
   it "does not return private inherited singleton methods for a subclass including a module" do
-    ReflectSpecs::C.singleton_methods(*@object).should_not include(:as_pri, :cs_pri)
+    ReflectSpecs::C.singleton_methods(*@object).should_not.include?(:as_pri)
+    ReflectSpecs::C.singleton_methods(*@object).should_not.include?(:cs_pri)
   end
 
   it "does not return private inherited singleton methods for a subclass of a class including a module" do
-    ReflectSpecs::E.singleton_methods(*@object).should_not include(:ds_pri, :es_pri)
+    ReflectSpecs::E.singleton_methods(*@object).should_not.include?(:ds_pri)
+    ReflectSpecs::E.singleton_methods(*@object).should_not.include?(:es_pri)
   end
 
   it "does not return private inherited singleton methods for a subclass of a class that includes a module, where the subclass also includes a module" do
-    ReflectSpecs::F.singleton_methods(*@object).should_not include(:ds_pri, :fs_pri)
+    ReflectSpecs::F.singleton_methods(*@object).should_not.include?(:ds_pri)
+    ReflectSpecs::F.singleton_methods(*@object).should_not.include?(:fs_pri)
   end
 end
 
@@ -165,11 +170,11 @@ describe "Kernel#singleton_methods" do
     it_behaves_like :kernel_singleton_methods_modules, nil, false
     it_behaves_like :kernel_singleton_methods_private_supers, nil, false
 
-    it "returns an empty Array for an object extented with a module" do
+    it "returns an empty Array for an object extended with a module" do
       ReflectSpecs.oe.singleton_methods(false).should == []
     end
 
-    it "returns an empty Array for an object extented with two modules" do
+    it "returns an empty Array for an object extended with two modules" do
       ReflectSpecs.oee.singleton_methods(false).should == []
     end
 
@@ -178,15 +183,17 @@ describe "Kernel#singleton_methods" do
     end
 
     it "returns the names of singleton methods of the subclass" do
-      ReflectSpecs::B.singleton_methods(false).should include(:bs_pro, :bs_pub)
+      ReflectSpecs::B.singleton_methods(false).to_set.should >= Set[:bs_pro, :bs_pub]
     end
 
     it "does not return names of inherited singleton methods for a subclass" do
-      ReflectSpecs::B.singleton_methods(false).should_not include(:as_pro, :as_pub)
+      ReflectSpecs::B.singleton_methods(false).should_not.include?(:as_pro)
+      ReflectSpecs::B.singleton_methods(false).should_not.include?(:as_pub)
     end
 
     it "does not return the names of inherited singleton methods for a class extended with a module" do
-      ReflectSpecs::P.singleton_methods(false).should_not include(:m_pro, :m_pub)
+      ReflectSpecs::P.singleton_methods(false).should_not.include?(:m_pro)
+      ReflectSpecs::P.singleton_methods(false).should_not.include?(:m_pub)
     end
   end
 end
diff --git a/spec/ruby/core/kernel/sleep_spec.rb b/spec/ruby/core/kernel/sleep_spec.rb
index 387dc4787b..61d8cc2380 100644
--- a/spec/ruby/core/kernel/sleep_spec.rb
+++ b/spec/ruby/core/kernel/sleep_spec.rb
@@ -1,20 +1,20 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
+require_relative '../fiber/fixtures/scheduler'
 
 describe "Kernel#sleep" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:sleep)
+    Kernel.private_instance_methods(false).should.include?(:sleep)
   end
 
   it "returns an Integer" do
-    sleep(0.001).should be_kind_of(Integer)
+    sleep(0.001).should.is_a?(Integer)
   end
 
   it "accepts a Float" do
     sleep(0.001).should >= 0
   end
 
-  it "accepts a Fixnum" do
+  it "accepts an Integer" do
     sleep(0).should >= 0
   end
 
@@ -22,17 +22,19 @@ describe "Kernel#sleep" do
     sleep(Rational(1, 999)).should >= 0
   end
 
-  it "raises an ArgumentError when passed a negative duration" do
-    -> { sleep(-0.1) }.should raise_error(ArgumentError)
-    -> { sleep(-1) }.should raise_error(ArgumentError)
+  it "accepts any Object that responds to divmod" do
+    o = Object.new
+    def o.divmod(*); [0, 0.001]; end
+    sleep(o).should >= 0
   end
 
-  it "raises a TypeError when passed nil" do
-    -> { sleep(nil)   }.should raise_error(TypeError)
+  it "raises an ArgumentError when passed a negative duration" do
+    -> { sleep(-0.1) }.should.raise(ArgumentError)
+    -> { sleep(-1) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { sleep('2')   }.should raise_error(TypeError)
+    -> { sleep('2')   }.should.raise(TypeError)
   end
 
   it "pauses execution indefinitely if not given a duration" do
@@ -49,6 +51,66 @@ describe "Kernel#sleep" do
     t.wakeup
     t.value.should == 5
   end
+
+  it "sleeps with nanosecond precision" do
+    start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    100.times do
+      sleep(0.0001)
+    end
+    end_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+    actual_duration = end_time - start_time
+    actual_duration.should > 0.01 # 100 * 0.0001 => 0.01
+  end
+
+  it "accepts a nil duration" do
+    running = false
+    t = Thread.new do
+      running = true
+      sleep(nil)
+      5
+    end
+
+    Thread.pass until running
+    Thread.pass while t.status and t.status != "sleep"
+
+    t.wakeup
+    t.value.should == 5
+  end
+
+  context "Kernel.sleep with Fiber scheduler" do
+    before :each do
+      Fiber.set_scheduler(FiberSpecs::LoggingScheduler.new)
+    end
+
+    after :each do
+      Fiber.set_scheduler(nil)
+    end
+
+    it "calls the scheduler without arguments when no duration is given" do
+      sleeper = Fiber.new(blocking: false) do
+        sleep
+      end
+      sleeper.resume
+      Fiber.scheduler.events.should == [{ event: :kernel_sleep, fiber: sleeper, args: [] }]
+    end
+
+    it "calls the scheduler with the given duration" do
+      sleeper = Fiber.new(blocking: false) do
+        sleep(0.01)
+      end
+      sleeper.resume
+      Fiber.scheduler.events.should == [{ event: :kernel_sleep, fiber: sleeper, args: [0.01] }]
+    end
+
+    it "does not call the scheduler if the fiber is blocking" do
+      sleeper = Fiber.new(blocking: true) do
+        sleep(0.01)
+      end
+      sleeper.resume
+      Fiber.scheduler.events.should == []
+    end
+  end
 end
 
 describe "Kernel.sleep" do
diff --git a/spec/ruby/core/kernel/spawn_spec.rb b/spec/ruby/core/kernel/spawn_spec.rb
index ba05b629d5..3432fc31da 100644
--- a/spec/ruby/core/kernel/spawn_spec.rb
+++ b/spec/ruby/core/kernel/spawn_spec.rb
@@ -6,7 +6,7 @@ require_relative 'fixtures/classes'
 # run here as it is redundant and takes too long for little gain.
 describe "Kernel#spawn" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:spawn)
+    Kernel.private_instance_methods(false).should.include?(:spawn)
   end
 
   it "executes the given command" do
diff --git a/spec/ruby/core/kernel/sprintf_spec.rb b/spec/ruby/core/kernel/sprintf_spec.rb
index 7adf71be76..5a4a90ff7a 100644
--- a/spec/ruby/core/kernel/sprintf_spec.rb
+++ b/spec/ruby/core/kernel/sprintf_spec.rb
@@ -3,22 +3,62 @@ require_relative 'fixtures/classes'
 require_relative 'shared/sprintf'
 require_relative 'shared/sprintf_encoding'
 
+describe :kernel_sprintf_to_str, shared: true do
+  it "calls #to_str to convert the format object to a String" do
+    obj = mock('format string')
+    obj.should_receive(:to_str).and_return("to_str: %i")
+    @method.call(obj, 42).should == "to_str: 42"
+  end
+end
+
 describe "Kernel#sprintf" do
   it_behaves_like :kernel_sprintf, -> format, *args {
-    sprintf(format, *args)
+    r = nil
+    -> {
+      r = sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
   }
 
   it_behaves_like :kernel_sprintf_encoding, -> format, *args {
-    sprintf(format, *args)
+    r = nil
+    -> {
+      r = sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
+  }
+
+  it_behaves_like :kernel_sprintf_to_str, -> format, *args {
+    r = nil
+    -> {
+      r = sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
   }
 end
 
 describe "Kernel.sprintf" do
   it_behaves_like :kernel_sprintf, -> format, *args {
-    Kernel.sprintf(format, *args)
+    r = nil
+    -> {
+      r = Kernel.sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
   }
 
   it_behaves_like :kernel_sprintf_encoding, -> format, *args {
-    Kernel.sprintf(format, *args)
+    r = nil
+    -> {
+      r = Kernel.sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
+  }
+
+  it_behaves_like :kernel_sprintf_to_str, -> format, *args {
+    r = nil
+    -> {
+      r = Kernel.sprintf(format, *args)
+    }.should_not complain(verbose: true)
+    r
   }
 end
diff --git a/spec/ruby/core/kernel/srand_spec.rb b/spec/ruby/core/kernel/srand_spec.rb
index 5454aae8cf..cbc3a7f4b8 100644
--- a/spec/ruby/core/kernel/srand_spec.rb
+++ b/spec/ruby/core/kernel/srand_spec.rb
@@ -1,9 +1,17 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe "Kernel.srand" do
+describe "Kernel#srand" do
+  before :each do
+    @seed = srand
+  end
+
+  after :each do
+    srand(@seed)
+  end
+
   it "is a private method" do
-    Kernel.should have_private_instance_method(:srand)
+    Kernel.private_instance_methods(false).should.include?(:srand)
   end
 
   it "returns the previous seed value" do
@@ -11,6 +19,10 @@ describe "Kernel.srand" do
     srand(20).should == 10
   end
 
+  it "returns the system-initialized seed value on the first call" do
+    ruby_exe('print srand(10)', options: '--disable-gems').should =~ /\A\d+\z/
+  end
+
   it "seeds the RNG correctly and repeatably" do
     srand(10)
     x = rand
@@ -19,7 +31,7 @@ describe "Kernel.srand" do
   end
 
   it "defaults number to a random value" do
-    -> { srand }.should_not raise_error
+    -> { srand }.should_not.raise
     srand.should_not == 0
   end
 
@@ -33,7 +45,7 @@ describe "Kernel.srand" do
     srand.should == -17
   end
 
-  it "accepts a Bignum as a seed" do
+  it "accepts an Integer as a seed" do
     srand(0x12345678901234567890)
     srand.should == 0x12345678901234567890
   end
@@ -48,14 +60,14 @@ describe "Kernel.srand" do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { srand(nil) }.should raise_error(TypeError)
+    -> { srand(nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { srand("7") }.should raise_error(TypeError)
+    -> { srand("7") }.should.raise(TypeError)
   end
 end
 
-describe "Kernel#srand" do
+describe "Kernel.srand" do
   it "needs to be reviewed for spec completeness"
 end
diff --git a/spec/ruby/core/kernel/sub_spec.rb b/spec/ruby/core/kernel/sub_spec.rb
index 9130bd159c..b175e371dc 100644
--- a/spec/ruby/core/kernel/sub_spec.rb
+++ b/spec/ruby/core/kernel/sub_spec.rb
@@ -6,13 +6,13 @@ require_relative 'fixtures/classes'
 ruby_version_is ""..."1.9" do
   describe "Kernel#sub" do
     it "is a private method" do
-      Kernel.should have_private_instance_method(:sub)
+      Kernel.private_instance_methods(false).should.include?(:sub)
     end
   end
 
   describe "Kernel#sub!" do
     it "is a private method" do
-      Kernel.should have_private_instance_method(:sub!)
+      Kernel.private_instance_methods(false).should.include?(:sub!)
     end
   end
 
diff --git a/spec/ruby/core/kernel/syscall_spec.rb b/spec/ruby/core/kernel/syscall_spec.rb
index 32d07b3ae2..63943cdad5 100644
--- a/spec/ruby/core/kernel/syscall_spec.rb
+++ b/spec/ruby/core/kernel/syscall_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#syscall" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:syscall)
+    Kernel.private_instance_methods(false).should.include?(:syscall)
   end
 end
 
diff --git a/spec/ruby/core/kernel/system_spec.rb b/spec/ruby/core/kernel/system_spec.rb
index 96c0496dd6..b24956104a 100644
--- a/spec/ruby/core/kernel/system_spec.rb
+++ b/spec/ruby/core/kernel/system_spec.rb
@@ -5,42 +5,40 @@ describe :kernel_system, shared: true do
   it "executes the specified command in a subprocess" do
     -> { @object.system("echo a") }.should output_to_fd("a\n")
 
-    $?.should be_an_instance_of Process::Status
-    $?.success?.should == true
+    $?.should.instance_of? Process::Status
+    $?.should.success?
   end
 
   it "returns true when the command exits with a zero exit status" do
     @object.system(ruby_cmd('exit 0')).should == true
 
-    $?.should be_an_instance_of Process::Status
-    $?.success?.should == true
+    $?.should.instance_of? Process::Status
+    $?.should.success?
     $?.exitstatus.should == 0
   end
 
   it "returns false when the command exits with a non-zero exit status" do
     @object.system(ruby_cmd('exit 1')).should == false
 
-    $?.should be_an_instance_of Process::Status
-    $?.success?.should == false
+    $?.should.instance_of? Process::Status
+    $?.should_not.success?
     $?.exitstatus.should == 1
   end
 
-  ruby_version_is "2.6" do
-    it "raises RuntimeError when `exception: true` is given and the command exits with a non-zero exit status" do
-      -> { @object.system(ruby_cmd('exit 1'), exception: true) }.should raise_error(RuntimeError)
-    end
+  it "raises RuntimeError when `exception: true` is given and the command exits with a non-zero exit status" do
+    -> { @object.system(ruby_cmd('exit 1'), exception: true) }.should.raise(RuntimeError)
+  end
 
-    it "raises Errno::ENOENT when `exception: true` is given and the specified command does not exist" do
-      -> { @object.system('feature_14386', exception: true) }.should raise_error(Errno::ENOENT)
-    end
+  it "raises Errno::ENOENT when `exception: true` is given and the specified command does not exist" do
+    -> { @object.system('feature_14386', exception: true) }.should.raise(Errno::ENOENT)
   end
 
   it "returns nil when command execution fails" do
-    @object.system("sad").should be_nil
+    @object.system("sad").should == nil
 
-    $?.should be_an_instance_of Process::Status
-    $?.pid.should be_kind_of(Integer)
-    $?.exitstatus.should == 127
+    $?.should.instance_of? Process::Status
+    $?.pid.should.is_a?(Integer)
+    $?.should_not.success?
   end
 
   it "does not write to stderr when command execution fails" do
@@ -66,6 +64,23 @@ describe :kernel_system, shared: true do
     end
   end
 
+  platform_is_not :windows do
+    before :each do
+      require 'tmpdir'
+      @shell_command = File.join(Dir.mktmpdir, "noshebang.cmd")
+      File.write(@shell_command, %[echo "$PATH"\n], perm: 0o700)
+    end
+
+    after :each do
+      File.unlink(@shell_command)
+      Dir.rmdir(File.dirname(@shell_command))
+    end
+
+    it "executes with `sh` if the command is executable but not binary and there is no shebang" do
+      -> { @object.system(@shell_command) }.should output_to_fd(ENV['PATH'] + "\n")
+    end
+  end
+
   before :each do
     ENV['TEST_SH_EXPANSION'] = 'foo'
     @shell_var = '$TEST_SH_EXPANSION'
@@ -106,7 +121,7 @@ end
 
 describe "Kernel#system" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:system)
+    Kernel.private_instance_methods(false).should.include?(:system)
   end
 
   it_behaves_like :kernel_system, :system, KernelSpecs::Method.new
diff --git a/spec/ruby/core/kernel/taint_spec.rb b/spec/ruby/core/kernel/taint_spec.rb
index 000295f6d2..9a2efbaea0 100644
--- a/spec/ruby/core/kernel/taint_spec.rb
+++ b/spec/ruby/core/kernel/taint_spec.rb
@@ -2,44 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#taint" do
-  it "returns self" do
-    o = Object.new
-    o.taint.should equal(o)
-  end
-
-  it "sets the tainted bit" do
-    o = Object.new
-    o.taint
-    o.tainted?.should == true
-  end
-
-  it "raises #{frozen_error_class} on an untainted, frozen object" do
-    o = Object.new.freeze
-    -> { o.taint }.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an error on a tainted, frozen object" do
-    o = Object.new.taint.freeze
-    o.taint.should equal(o)
-  end
-
-  it "has no effect on immediate values" do
-    [nil, true, false].each do |v|
-      v.taint
-      v.tainted?.should == false
-    end
-  end
-
-  it "no raises a RuntimeError on symbols" do
-    v = :sym
-    -> { v.taint }.should_not raise_error(RuntimeError)
-    v.tainted?.should == false
-  end
-
-  it "no raises error on fixnum values" do
-    [1].each do |v|
-      -> { v.taint }.should_not raise_error(RuntimeError)
-      v.tainted?.should == false
-    end
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:taint)
   end
 end
diff --git a/spec/ruby/core/kernel/tainted_spec.rb b/spec/ruby/core/kernel/tainted_spec.rb
index c024756110..837eb1dafb 100644
--- a/spec/ruby/core/kernel/tainted_spec.rb
+++ b/spec/ruby/core/kernel/tainted_spec.rb
@@ -2,11 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#tainted?" do
-  it "returns true if Object is tainted" do
-    o = mock('o')
-    p = mock('p')
-    p.taint
-    o.tainted?.should == false
-    p.tainted?.should == true
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:tainted?)
   end
 end
diff --git a/spec/ruby/core/kernel/tap_spec.rb b/spec/ruby/core/kernel/tap_spec.rb
index f7720a6dc7..453b9b84d5 100644
--- a/spec/ruby/core/kernel/tap_spec.rb
+++ b/spec/ruby/core/kernel/tap_spec.rb
@@ -4,10 +4,10 @@ require_relative 'fixtures/classes'
 describe "Kernel#tap" do
   it "always yields self and returns self" do
     a = KernelSpecs::A.new
-    a.tap{|o| o.should equal(a); 42}.should equal(a)
+    a.tap{|o| o.should.equal?(a); 42}.should.equal?(a)
   end
 
   it "raises a LocalJumpError when no block given" do
-    -> { 3.tap }.should raise_error(LocalJumpError)
+    -> { 3.tap }.should.raise(LocalJumpError)
   end
 end
diff --git a/spec/ruby/core/kernel/test_spec.rb b/spec/ruby/core/kernel/test_spec.rb
index abb365aed2..30717dfd98 100644
--- a/spec/ruby/core/kernel/test_spec.rb
+++ b/spec/ruby/core/kernel/test_spec.rb
@@ -3,12 +3,12 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#test" do
   before :all do
-    @file = File.dirname(__FILE__) + '/fixtures/classes.rb'
-    @dir = File.dirname(__FILE__) + '/fixtures'
+    @file = __dir__ + '/fixtures/classes.rb'
+    @dir = __dir__ + '/fixtures'
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:test)
+    Kernel.private_instance_methods(false).should.include?(:test)
   end
 
   it "returns true when passed ?f if the argument is a regular file" do
@@ -28,7 +28,7 @@ describe "Kernel#test" do
       link = tmp("file_symlink.lnk")
       File.symlink(@file, link)
       begin
-        Kernel.test(?l, link).should be_true
+        Kernel.test(?l, link).should == true
       ensure
         rm_r link
       end
@@ -36,11 +36,11 @@ describe "Kernel#test" do
   end
 
   it "returns true when passed ?r if the argument is readable by the effective uid" do
-    Kernel.test(?r, @file).should be_true
+    Kernel.test(?r, @file).should == true
   end
 
   it "returns true when passed ?R if the argument is readable by the real uid" do
-    Kernel.test(?R, @file).should be_true
+    Kernel.test(?R, @file).should == true
   end
 
   context "writable test" do
@@ -54,11 +54,11 @@ describe "Kernel#test" do
     end
 
     it "returns true when passed ?w if the argument is readable by the effective uid" do
-      Kernel.test(?w, @tmp_file).should be_true
+      Kernel.test(?w, @tmp_file).should == true
     end
 
     it "returns true when passed ?W if the argument is readable by the real uid" do
-      Kernel.test(?W, @tmp_file).should be_true
+      Kernel.test(?W, @tmp_file).should == true
     end
   end
 
diff --git a/spec/ruby/core/kernel/then_spec.rb b/spec/ruby/core/kernel/then_spec.rb
index fa896b52b1..8109a2960a 100644
--- a/spec/ruby/core/kernel/then_spec.rb
+++ b/spec/ruby/core/kernel/then_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/then'
 
-ruby_version_is "2.6" do
-  describe "Kernel#then" do
-    it_behaves_like :kernel_then, :then
-  end
+describe "Kernel#then" do
+  it_behaves_like :kernel_then, :then
 end
diff --git a/spec/ruby/core/kernel/throw_spec.rb b/spec/ruby/core/kernel/throw_spec.rb
index 64bfccb413..1086126176 100644
--- a/spec/ruby/core/kernel/throw_spec.rb
+++ b/spec/ruby/core/kernel/throw_spec.rb
@@ -7,7 +7,7 @@ describe "Kernel.throw" do
       :value
       throw :blah
       fail("throw didn't transfer the control")
-    end.should be_nil
+    end.should == nil
   end
 
   it "transfers control to the innermost catch block waiting for the same symbol" do
@@ -42,11 +42,11 @@ describe "Kernel.throw" do
   end
 
   it "raises an ArgumentError if there is no catch block for the symbol" do
-    -> { throw :blah }.should raise_error(ArgumentError)
+    -> { throw :blah }.should.raise(ArgumentError)
   end
 
   it "raises an UncaughtThrowError if there is no catch block for the symbol" do
-    -> { throw :blah }.should raise_error(UncaughtThrowError)
+    -> { throw :blah }.should.raise(UncaughtThrowError)
   end
 
   it "raises ArgumentError if 3 or more arguments provided" do
@@ -54,13 +54,13 @@ describe "Kernel.throw" do
       catch :blah do
         throw :blah, :return_value, 2
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       catch :blah do
         throw :blah, :return_value, 2, 3, 4, 5
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "can throw an object" do
@@ -69,12 +69,12 @@ describe "Kernel.throw" do
       catch obj do
         throw obj
       end
-    }.should_not raise_error(NameError)
+    }.should_not.raise(NameError)
   end
 end
 
 describe "Kernel#throw" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:throw)
+    Kernel.private_instance_methods(false).should.include?(:throw)
   end
 end
diff --git a/spec/ruby/core/kernel/to_s_spec.rb b/spec/ruby/core/kernel/to_s_spec.rb
index 4b59520ce7..ea4b00151e 100644
--- a/spec/ruby/core/kernel/to_s_spec.rb
+++ b/spec/ruby/core/kernel/to_s_spec.rb
@@ -5,12 +5,4 @@ describe "Kernel#to_s" do
   it "returns a String containing the name of self's class" do
     Object.new.to_s.should =~ /Object/
   end
-
-  it "returns a tainted result if self is tainted" do
-    Object.new.taint.to_s.tainted?.should be_true
-  end
-
-  it "returns an untrusted result if self is untrusted" do
-    Object.new.untrust.to_s.untrusted?.should be_true
-  end
 end
diff --git a/spec/ruby/core/kernel/trace_var_spec.rb b/spec/ruby/core/kernel/trace_var_spec.rb
index 3c84aa5e60..150c3da266 100644
--- a/spec/ruby/core/kernel/trace_var_spec.rb
+++ b/spec/ruby/core/kernel/trace_var_spec.rb
@@ -14,7 +14,7 @@ describe "Kernel#trace_var" do
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:trace_var)
+    Kernel.private_instance_methods(false).should.include?(:trace_var)
   end
 
   it "hooks assignments to a global variable" do
@@ -49,6 +49,6 @@ describe "Kernel#trace_var" do
   it "raises ArgumentError if no block or proc is provided" do
     -> do
       trace_var :$Kernel_trace_var_global
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/kernel/trap_spec.rb b/spec/ruby/core/kernel/trap_spec.rb
index 465aacb0fb..8f44f3af4b 100644
--- a/spec/ruby/core/kernel/trap_spec.rb
+++ b/spec/ruby/core/kernel/trap_spec.rb
@@ -1,12 +1,9 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
 
 describe "Kernel#trap" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:trap)
+    Kernel.private_instance_methods(false).should.include?(:trap)
   end
-end
 
-describe "Kernel.trap" do
-  it "needs to be reviewed for spec completeness"
+  # Behaviour is specified for Signal.trap
 end
diff --git a/spec/ruby/core/kernel/trust_spec.rb b/spec/ruby/core/kernel/trust_spec.rb
index d34aa293ec..ef3fa9a3e1 100644
--- a/spec/ruby/core/kernel/trust_spec.rb
+++ b/spec/ruby/core/kernel/trust_spec.rb
@@ -2,24 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#trust" do
-  it "returns self" do
-    o = Object.new
-    o.trust.should equal(o)
-  end
-
-  it "clears the untrusted bit" do
-    o = Object.new.untrust
-    o.trust
-    o.untrusted?.should == false
-  end
-
-  it "raises #{frozen_error_class} on an untrusted, frozen object" do
-    o = Object.new.untrust.freeze
-    -> { o.trust }.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an error on a trusted, frozen object" do
-    o = Object.new.freeze
-    o.trust.should equal(o)
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:trust)
   end
 end
diff --git a/spec/ruby/core/kernel/untaint_spec.rb b/spec/ruby/core/kernel/untaint_spec.rb
index 94e4a8fd44..47e8544bd4 100644
--- a/spec/ruby/core/kernel/untaint_spec.rb
+++ b/spec/ruby/core/kernel/untaint_spec.rb
@@ -2,24 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#untaint" do
-  it "returns self" do
-    o = Object.new
-    o.untaint.should equal(o)
-  end
-
-  it "clears the tainted bit" do
-    o = Object.new.taint
-    o.untaint
-    o.tainted?.should == false
-  end
-
-  it "raises #{frozen_error_class} on a tainted, frozen object" do
-    o = Object.new.taint.freeze
-    -> { o.untaint }.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an error on an untainted, frozen object" do
-    o = Object.new.freeze
-    o.untaint.should equal(o)
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:untaint)
   end
 end
diff --git a/spec/ruby/core/kernel/untrace_var_spec.rb b/spec/ruby/core/kernel/untrace_var_spec.rb
index 1925a3a836..8b219801c8 100644
--- a/spec/ruby/core/kernel/untrace_var_spec.rb
+++ b/spec/ruby/core/kernel/untrace_var_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#untrace_var" do
   it "is a private method" do
-    Kernel.should have_private_instance_method(:untrace_var)
+    Kernel.private_instance_methods(false).should.include?(:untrace_var)
   end
 end
 
diff --git a/spec/ruby/core/kernel/untrust_spec.rb b/spec/ruby/core/kernel/untrust_spec.rb
index 2ee3dbb170..8787ab3fc9 100644
--- a/spec/ruby/core/kernel/untrust_spec.rb
+++ b/spec/ruby/core/kernel/untrust_spec.rb
@@ -2,24 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#untrust" do
-  it "returns self" do
-    o = Object.new
-    o.untrust.should equal(o)
-  end
-
-  it "sets the untrusted bit" do
-    o = Object.new
-    o.untrust
-    o.untrusted?.should == true
-  end
-
-  it "raises #{frozen_error_class} on a trusted, frozen object" do
-    o = Object.new.freeze
-    -> { o.untrust }.should raise_error(frozen_error_class)
-  end
-
-  it "does not raise an error on an untrusted, frozen object" do
-    o = Object.new.untrust.freeze
-    o.untrust.should equal(o)
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:untrust)
   end
 end
diff --git a/spec/ruby/core/kernel/untrusted_spec.rb b/spec/ruby/core/kernel/untrusted_spec.rb
index 3f894b0bab..29261be9c4 100644
--- a/spec/ruby/core/kernel/untrusted_spec.rb
+++ b/spec/ruby/core/kernel/untrusted_spec.rb
@@ -2,27 +2,7 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#untrusted?" do
-  it "returns the untrusted status of an object" do
-    o = mock('o')
-    o.untrusted?.should == false
-    o.untrust
-    o.untrusted?.should == true
-  end
-
-  it "has no effect on immediate values" do
-    a = nil
-    b = true
-    c = false
-    a.untrust
-    b.untrust
-    c.untrust
-    a.untrusted?.should == false
-    b.untrusted?.should == false
-    c.untrusted?.should == false
-  end
-
-  it "has effect on immediate values" do
-    d = 1
-    -> { d.untrust }.should_not raise_error(RuntimeError)
+  it "has been removed" do
+    Object.new.should_not.respond_to?(:untrusted?)
   end
 end
diff --git a/spec/ruby/core/kernel/warn_spec.rb b/spec/ruby/core/kernel/warn_spec.rb
index 2a404a2a35..189129dd31 100644
--- a/spec/ruby/core/kernel/warn_spec.rb
+++ b/spec/ruby/core/kernel/warn_spec.rb
@@ -8,15 +8,16 @@ describe "Kernel#warn" do
   end
 
   after :each do
-    $VERBOSE = @before_verbose
+    $VERBOSE = nil
     $/ = @before_separator
+    $VERBOSE = @before_verbose
   end
 
   it "is a private method" do
-    Kernel.should have_private_instance_method(:warn)
+    Kernel.private_instance_methods(false).should.include?(:warn)
   end
 
-  it "requires multiple arguments" do
+  it "accepts multiple arguments" do
     Kernel.method(:warn).arity.should < 0
   end
 
@@ -86,71 +87,212 @@ describe "Kernel#warn" do
     }.should output(nil, "to_s called\n")
   end
 
-  ruby_version_is "2.5" do
-    describe ":uplevel keyword argument" do
-      before :each do
-        $VERBOSE = true
-      end
+  describe ":uplevel keyword argument" do
+    before :each do
+      $VERBOSE = true
+    end
 
-      it "prepends a message with specified line from the backtrace" do
-        w = KernelSpecs::WarnInNestedCall.new
+    it "prepends a message with specified line from the backtrace" do
+      w = KernelSpecs::WarnInNestedCall.new
 
-        -> { w.f4("foo", 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: foo|)
-        -> { w.f4("foo", 1) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f1_call_lineno}: warning: foo|)
-        -> { w.f4("foo", 2) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f2_call_lineno}: warning: foo|)
-        -> { w.f4("foo", 3) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f3_call_lineno}: warning: foo|)
-      end
+      -> { w.f4("foo", 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: foo|)
+      -> { w.f4("foo", 1) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f1_call_lineno}: warning: foo|)
+      -> { w.f4("foo", 2) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f2_call_lineno}: warning: foo|)
+      -> { w.f4("foo", 3) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f3_call_lineno}: warning: foo|)
+    end
 
-      it "converts first arg using to_s" do
-        w = KernelSpecs::WarnInNestedCall.new
+    # Test both explicitly without and with RubyGems as RubyGems overrides Kernel#warn
+    it "shows the caller of #require and not #require itself without RubyGems" do
+      file = fixture(__FILE__ , "warn_require_caller.rb")
+      ruby_exe(file, options: "--disable-gems", args: "2>&1").should == "#{file}:2: warning: warn-require-warning\n"
+    end
 
-        -> { w.f4(false, 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: false|)
-        -> { w.f4(nil, 1) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f1_call_lineno}: warning: |)
-        obj = mock("obj")
-        obj.should_receive(:to_s).and_return("to_s called")
-        -> { w.f4(obj, 2) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f2_call_lineno}: warning: to_s called|)
-      end
+    it "shows the caller of #require and not #require itself with RubyGems loaded" do
+      file = fixture(__FILE__ , "warn_require_caller.rb")
+      ruby_exe(file, options: "-rrubygems", args: "2>&1").should == "#{file}:2: warning: warn-require-warning\n"
+    end
 
-      it "does not prepend caller information if line number is too big" do
-        w = KernelSpecs::WarnInNestedCall.new
-        -> { w.f4("foo", 100) }.should output(nil, "warning: foo\n")
-      end
+    it "doesn't show the caller when the uplevel is `nil`" do
+      w = KernelSpecs::WarnInNestedCall.new
 
-      it "prepends even if a message is empty or nil" do
-        w = KernelSpecs::WarnInNestedCall.new
+      -> { w.f4("foo", nil) }.should output(nil, "foo\n")
+    end
+
+    guard -> { Kernel.instance_method(:tap).source_location } do
+      it "skips <internal: core library methods defined in Ruby" do
+        file, line = Kernel.instance_method(:tap).source_location
+        file.should.start_with?('<internal:')
 
-        -> { w.f4("", 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: \n$|)
-        -> { w.f4(nil, 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: \n$|)
+        file = fixture(__FILE__ , "warn_core_method.rb")
+        n = 9
+        ruby_exe(file, options: "--disable-gems", args: "2>&1").lines.should == [
+          "#{file}:#{n+0}: warning: use X instead\n",
+          "#{file}:#{n+1}: warning: use X instead\n",
+          "#{file}:#{n+2}: warning: use X instead\n",
+          "#{file}:#{n+4}: warning: use X instead\n",
+        ]
       end
+    end
 
-      it "converts value to Integer" do
-        w = KernelSpecs::WarnInNestedCall.new
+    it "accepts :category keyword with a symbol" do
+      -> {
+        $VERBOSE = true
+        warn("message", category: :deprecated)
+      }.should output(nil, "message\n")
+    end
 
-        -> { w.f4(0.1) }.should output(nil, %r|classes.rb:#{w.warn_call_lineno}:|)
-        -> { w.f4(Rational(1, 2)) }.should output(nil, %r|classes.rb:#{w.warn_call_lineno}:|)
-      end
+    it "accepts :category keyword with nil" do
+      -> {
+        $VERBOSE = true
+        warn("message", category: nil)
+      }.should output(nil, "message\n")
+    end
 
-      it "raises ArgumentError if passed negative value" do
-        -> { warn "", uplevel: -2 }.should raise_error(ArgumentError)
-        -> { warn "", uplevel: -100 }.should raise_error(ArgumentError)
-      end
+    it "accepts :category keyword with object convertible to symbol" do
+      o = Object.new
+      def o.to_sym; :deprecated; end
+      -> {
+        $VERBOSE = true
+        warn("message", category: o)
+      }.should output(nil, "message\n")
+    end
 
-      it "raises ArgumentError if passed -1" do
-        -> { warn "", uplevel: -1 }.should raise_error(ArgumentError)
+    it "raises if :category keyword is not nil and not convertible to symbol" do
+      -> {
+        $VERBOSE = true
+        warn("message", category: Object.new)
+      }.should.raise(TypeError)
+    end
+
+    it "converts first arg using to_s" do
+      w = KernelSpecs::WarnInNestedCall.new
+
+      -> { w.f4(false, 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: false|)
+      -> { w.f4(nil, 1) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f1_call_lineno}: warning: |)
+      obj = mock("obj")
+      obj.should_receive(:to_s).and_return("to_s called")
+      -> { w.f4(obj, 2) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.f2_call_lineno}: warning: to_s called|)
+    end
+
+    it "does not prepend caller information if the uplevel argument is too large" do
+      w = KernelSpecs::WarnInNestedCall.new
+      -> { w.f4("foo", 100) }.should output(nil, "warning: foo\n")
+    end
+
+    it "prepends even if a message is empty or nil" do
+      w = KernelSpecs::WarnInNestedCall.new
+
+      -> { w.f4("", 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: \n$|)
+      -> { w.f4(nil, 0) }.should output(nil, %r|core/kernel/fixtures/classes.rb:#{w.warn_call_lineno}: warning: \n$|)
+    end
+
+    it "converts value to Integer" do
+      w = KernelSpecs::WarnInNestedCall.new
+
+      -> { w.f4(0.1) }.should output(nil, %r|classes.rb:#{w.warn_call_lineno}:|)
+      -> { w.f4(Rational(1, 2)) }.should output(nil, %r|classes.rb:#{w.warn_call_lineno}:|)
+    end
+
+    it "raises ArgumentError if passed negative value" do
+      -> { warn "", uplevel: -2 }.should.raise(ArgumentError)
+      -> { warn "", uplevel: -100 }.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError if passed -1" do
+      -> { warn "", uplevel: -1 }.should.raise(ArgumentError)
+    end
+
+    it "raises TypeError if passed not Integer" do
+      -> { warn "", uplevel: "" }.should.raise(TypeError)
+      -> { warn "", uplevel: [] }.should.raise(TypeError)
+      -> { warn "", uplevel: {} }.should.raise(TypeError)
+      -> { warn "", uplevel: Object.new }.should.raise(TypeError)
+    end
+  end
+
+  it "treats empty hash as no keyword argument" do
+    h = {}
+    -> { warn(**h) }.should_not complain(verbose: true)
+    -> { warn('foo', **h) }.should complain("foo\n")
+  end
+
+  it "calls Warning.warn without keyword arguments if Warning.warn does not accept keyword arguments" do
+    verbose = $VERBOSE
+    $VERBOSE = false
+    class << Warning
+      alias_method :_warn, :warn
+      def warn(message)
+        ScratchPad.record(message)
       end
+    end
 
-      it "raises TypeError if passed not Integer" do
-        -> { warn "", uplevel: "" }.should raise_error(TypeError)
-        -> { warn "", uplevel: [] }.should raise_error(TypeError)
-        -> { warn "", uplevel: {} }.should raise_error(TypeError)
-        -> { warn "", uplevel: Object.new }.should raise_error(TypeError)
+    begin
+      ScratchPad.clear
+      Kernel.warn("Chunky bacon!")
+      ScratchPad.recorded.should == "Chunky bacon!\n"
+
+      Kernel.warn("Deprecated bacon!", category: :deprecated)
+      ScratchPad.recorded.should == "Deprecated bacon!\n"
+    ensure
+      class << Warning
+        remove_method :warn
+        alias_method :warn, :_warn
+        remove_method :_warn
       end
+      $VERBOSE = verbose
+    end
+  end
+
+  it "calls Warning.warn with category: nil if Warning.warn accepts keyword arguments" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: nil)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!")
+    ensure
+      $VERBOSE = verbose
+    end
+  end
+
+  it "calls Warning.warn with given category keyword converted to a symbol" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: :deprecated)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!", category: 'deprecated')
+    ensure
+      $VERBOSE = verbose
     end
+  end
 
-    it "treats empty hash as no keyword argument" do
-      h = {}
-      -> { warn(**h) }.should_not complain(verbose: true)
-      -> { warn('foo', **h) }.should complain("foo\n")
+  it "does not call Warning.warn if self is the Warning module" do
+    # RubyGems redefines Kernel#warn so we need to use a subprocess and disable RubyGems here
+    code = <<-RUBY
+    def Warning.warn(*args, **kwargs)
+      raise 'should not be called'
+    end
+    Kernel.instance_method(:warn).bind(Warning).call('Kernel#warn spec edge case')
+    RUBY
+    out = ruby_exe(code, args: "2>&1", options: "--disable-gems")
+    out.should == "Kernel#warn spec edge case\n"
+    $?.should.success?
+  end
+
+  it "avoids recursion if Warning#warn is redefined and calls super" do
+    # This works because of the spec above, which is the workaround for it.
+    # Note that redefining Warning#warn is a mistake which would naturally end in infinite recursion,
+    # Warning.extend Module.new { def warn } should be used instead.
+    # RubyGems redefines Kernel#warn so we need to use a subprocess and disable RubyGems here
+    code = <<-RUBY
+    module Warning
+      def warn(*args, **kwargs)
+        super
+      end
     end
+    warn "avoid infinite recursion"
+    RUBY
+    out = ruby_exe(code, args: "2>&1", options: "--disable-gems")
+    out.should == "avoid infinite recursion\n"
+    $?.should.success?
   end
 end
diff --git a/spec/ruby/core/kernel/yield_self_spec.rb b/spec/ruby/core/kernel/yield_self_spec.rb
index affedae144..e311dcee47 100644
--- a/spec/ruby/core/kernel/yield_self_spec.rb
+++ b/spec/ruby/core/kernel/yield_self_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/then'
 
-ruby_version_is "2.5" do
-  describe "Kernel#yield_self" do
-    it_behaves_like :kernel_then, :yield_self
-  end
+describe "Kernel#yield_self" do
+  it_behaves_like :kernel_then, :yield_self
 end
diff --git a/spec/ruby/core/main/define_method_spec.rb b/spec/ruby/core/main/define_method_spec.rb
index d85c5e8119..5279d078c3 100644
--- a/spec/ruby/core/main/define_method_spec.rb
+++ b/spec/ruby/core/main/define_method_spec.rb
@@ -14,15 +14,15 @@ describe "main#define_method" do
 
   it 'creates a public method in TOPLEVEL_BINDING' do
     eval @code, TOPLEVEL_BINDING
-    Object.should have_method :boom
+    Object.should.respond_to? :boom
   end
 
   it 'creates a public method in script binding' do
     eval @code, script_binding
-    Object.should have_method :boom
+    Object.should.respond_to? :boom
   end
 
   it 'returns the method name as symbol' do
-    eval(@code, TOPLEVEL_BINDING).should equal :boom
+    eval(@code, TOPLEVEL_BINDING).should.equal? :boom
   end
 end
diff --git a/spec/ruby/core/main/fixtures/classes.rb b/spec/ruby/core/main/fixtures/classes.rb
index 6aba948ce0..757cee4e4a 100644
--- a/spec/ruby/core/main/fixtures/classes.rb
+++ b/spec/ruby/core/main/fixtures/classes.rb
@@ -13,6 +13,14 @@ def main_public_method
 end
 public :main_public_method
 
+def main_public_method2
+end
+public :main_public_method2
+
 def main_private_method
 end
 private :main_private_method
+
+def main_private_method2
+end
+private :main_private_method2
diff --git a/spec/ruby/core/main/fixtures/using.rb b/spec/ruby/core/main/fixtures/using.rb
new file mode 100644
index 0000000000..30713ef309
--- /dev/null
+++ b/spec/ruby/core/main/fixtures/using.rb
@@ -0,0 +1 @@
+using Module.new
diff --git a/spec/ruby/core/main/fixtures/using_in_main.rb b/spec/ruby/core/main/fixtures/using_in_main.rb
new file mode 100644
index 0000000000..a4a71c89cc
--- /dev/null
+++ b/spec/ruby/core/main/fixtures/using_in_main.rb
@@ -0,0 +1,5 @@
+MAIN = self
+
+module X
+  MAIN.send(:using, Module.new)
+end
diff --git a/spec/ruby/core/main/fixtures/using_in_method.rb b/spec/ruby/core/main/fixtures/using_in_method.rb
new file mode 100644
index 0000000000..d9ea2e9ef0
--- /dev/null
+++ b/spec/ruby/core/main/fixtures/using_in_method.rb
@@ -0,0 +1,5 @@
+def foo
+  using Module.new
+end
+
+foo
diff --git a/spec/ruby/core/main/include_spec.rb b/spec/ruby/core/main/include_spec.rb
index 9f5a5f54ea..09f8d4d3b5 100644
--- a/spec/ruby/core/main/include_spec.rb
+++ b/spec/ruby/core/main/include_spec.rb
@@ -4,13 +4,13 @@ require_relative 'fixtures/classes'
 describe "main#include" do
   it "includes the given Module in Object" do
     eval "include MainSpecs::Module", TOPLEVEL_BINDING
-    Object.ancestors.should include(MainSpecs::Module)
+    Object.ancestors.should.include?(MainSpecs::Module)
   end
 
   context "in a file loaded with wrapping" do
     it "includes the given Module in the load wrapper" do
       load(File.expand_path("../fixtures/wrapped_include.rb", __FILE__), true)
-      Object.ancestors.should_not include(MainSpecs::WrapIncludeModule)
+      Object.ancestors.should_not.include?(MainSpecs::WrapIncludeModule)
     end
   end
 end
diff --git a/spec/ruby/core/main/private_spec.rb b/spec/ruby/core/main/private_spec.rb
index e34e0c7b7b..56a39ae3c1 100644
--- a/spec/ruby/core/main/private_spec.rb
+++ b/spec/ruby/core/main/private_spec.rb
@@ -4,20 +4,39 @@ require_relative 'fixtures/classes'
 describe "main#private" do
   after :each do
     Object.send(:public, :main_public_method)
+    Object.send(:public, :main_public_method2)
   end
 
-  it "sets the visibility of the given method to private" do
-    eval "private :main_public_method", TOPLEVEL_BINDING
-    Object.should have_private_method(:main_public_method)
+  context "when single argument is passed and it is not an array" do
+    it "sets the visibility of the given methods to private" do
+      eval "private :main_public_method", TOPLEVEL_BINDING
+      Object.private_methods(true).should.include?(:main_public_method)
+    end
   end
 
-  it "returns Object" do
-    eval("private :main_public_method", TOPLEVEL_BINDING).should equal(Object)
+  context "when multiple arguments are passed" do
+    it "sets the visibility of the given methods to private" do
+      eval "private :main_public_method, :main_public_method2", TOPLEVEL_BINDING
+      Object.private_methods(true).should.include?(:main_public_method)
+      Object.private_methods(true).should.include?(:main_public_method2)
+    end
   end
 
-  it "raises a NameError when given an undefined name" do
+  context "when single argument is passed and is an array" do
+    it "sets the visibility of the given methods to private" do
+      eval "private [:main_public_method, :main_public_method2]", TOPLEVEL_BINDING
+      Object.private_methods(true).should.include?(:main_public_method)
+      Object.private_methods(true).should.include?(:main_public_method2)
+    end
+  end
+
+  it "returns argument" do
+    eval("private :main_public_method", TOPLEVEL_BINDING).should.equal?(:main_public_method)
+  end
+
+  it "raises a NameError when at least one of given method names is undefined" do
     -> do
-      eval "private :main_undefined_method", TOPLEVEL_BINDING
-    end.should raise_error(NameError)
+      eval "private :main_public_method, :main_undefined_method", TOPLEVEL_BINDING
+    end.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/main/public_spec.rb b/spec/ruby/core/main/public_spec.rb
index afe25c705a..89368ebb0d 100644
--- a/spec/ruby/core/main/public_spec.rb
+++ b/spec/ruby/core/main/public_spec.rb
@@ -4,20 +4,40 @@ require_relative 'fixtures/classes'
 describe "main#public" do
   after :each do
     Object.send(:private, :main_private_method)
+    Object.send(:private, :main_private_method2)
   end
 
-  it "sets the visibility of the given method to public" do
-    eval "public :main_private_method", TOPLEVEL_BINDING
-    Object.should_not have_private_method(:main_private_method)
+  context "when single argument is passed and it is not an array" do
+    it "sets the visibility of the given methods to public" do
+      eval "public :main_private_method", TOPLEVEL_BINDING
+      Object.private_methods(true).should_not.include?(:main_private_method)
+    end
   end
 
-  it "returns Object" do
-    eval("public :main_private_method", TOPLEVEL_BINDING).should equal(Object)
+  context "when multiple arguments are passed" do
+    it "sets the visibility of the given methods to public" do
+      eval "public :main_private_method, :main_private_method2", TOPLEVEL_BINDING
+      Object.private_methods(true).should_not.include?(:main_private_method)
+      Object.private_methods(true).should_not.include?(:main_private_method2)
+    end
   end
 
+  context "when single argument is passed and is an array" do
+    it "sets the visibility of the given methods to public" do
+      eval "public [:main_private_method, :main_private_method2]", TOPLEVEL_BINDING
+      Object.private_methods(true).should_not.include?(:main_private_method)
+      Object.private_methods(true).should_not.include?(:main_private_method2)
+    end
+  end
+
+  it "returns argument" do
+    eval("public :main_private_method", TOPLEVEL_BINDING).should.equal?(:main_private_method)
+  end
+
+
   it "raises a NameError when given an undefined name" do
     -> do
       eval "public :main_undefined_method", TOPLEVEL_BINDING
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/main/ruby2_keywords_spec.rb b/spec/ruby/core/main/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..d12c0ed4e4
--- /dev/null
+++ b/spec/ruby/core/main/ruby2_keywords_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "main.ruby2_keywords" do
+  it "is the same as Object.ruby2_keywords" do
+    main = TOPLEVEL_BINDING.receiver
+    main.private_methods(false).should.include?(:ruby2_keywords)
+  end
+end
diff --git a/spec/ruby/core/main/using_spec.rb b/spec/ruby/core/main/using_spec.rb
index f9f709f7dc..314a6be416 100644
--- a/spec/ruby/core/main/using_spec.rb
+++ b/spec/ruby/core/main/using_spec.rb
@@ -5,11 +5,11 @@ describe "main.using" do
   it "requires one Module argument" do
     -> do
       eval('using', TOPLEVEL_BINDING)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
 
     -> do
       eval('using "foo"', TOPLEVEL_BINDING)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "uses refinements from the given module only in the target file" do
@@ -19,7 +19,7 @@ describe "main.using" do
     MainSpecs::DATA[:toplevel].should == 'foo'
     -> do
       'hello'.foo
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 
   it "uses refinements from the given module for method calls in the target file" do
@@ -27,7 +27,7 @@ describe "main.using" do
     load File.expand_path('../fixtures/string_refinement_user.rb', __FILE__)
     -> do
       'hello'.foo
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
     MainSpecs.call_foo('hello').should == 'foo'
   end
 
@@ -129,4 +129,22 @@ describe "main.using" do
 
     x.call_bar(cls2.new).should == 'bar'
   end
+
+  it "raises error when called from method in wrapped script" do
+    -> do
+      load File.expand_path('../fixtures/using_in_method.rb', __FILE__), true
+    end.should.raise(RuntimeError)
+  end
+
+  it "raises error when called on toplevel from module" do
+    -> do
+      load File.expand_path('../fixtures/using_in_main.rb', __FILE__), true
+    end.should.raise(RuntimeError)
+  end
+
+  it "does not raise error when wrapped with module" do
+    -> do
+      load File.expand_path('../fixtures/using.rb', __FILE__), true
+    end.should_not.raise
+  end
 end
diff --git a/spec/ruby/core/marshal/dump_spec.rb b/spec/ruby/core/marshal/dump_spec.rb
index 700f090a2f..9bbb7809af 100644
--- a/spec/ruby/core/marshal/dump_spec.rb
+++ b/spec/ruby/core/marshal/dump_spec.rb
@@ -1,5 +1,6 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 require_relative 'fixtures/marshal_data'
 
 describe "Marshal.dump" do
@@ -37,7 +38,7 @@ describe "Marshal.dump" do
       ].should be_computed_by(:dump)
     end
 
-    platform_is wordsize: 64 do
+    platform_is c_long_size: 64 do
       it "dumps a positive Fixnum > 31 bits as a Bignum" do
         Marshal.dump(2**31 + 1).should == "\x04\bl+\a\x01\x00\x00\x80"
       end
@@ -46,6 +47,11 @@ describe "Marshal.dump" do
         Marshal.dump(-2**31 - 1).should == "\x04\bl-\a\x01\x00\x00\x80"
       end
     end
+
+    it "does not use object links for objects repeatedly dumped" do
+      Marshal.dump([0, 0]).should == "\x04\b[\ai\x00i\x00"
+      Marshal.dump([2**16, 2**16]).should == "\x04\b[\ai\x03\x00\x00\x01i\x03\x00\x00\x01"
+    end
   end
 
   describe "with a Symbol" do
@@ -75,9 +81,28 @@ describe "Marshal.dump" do
     end
 
     it "dumps a binary encoded Symbol" do
-      s = "\u2192".force_encoding("binary").to_sym
+      s = "\u2192".dup.force_encoding("binary").to_sym
       Marshal.dump(s).should == "\x04\b:\b\xE2\x86\x92"
     end
+
+    it "dumps multiple Symbols sharing the same encoding" do
+      # Note that the encoding is a link for the second Symbol
+      symbol1 = "I:\t\xE2\x82\xACa\x06:\x06ET"
+      symbol2 = "I:\t\xE2\x82\xACb\x06;\x06T"
+      value = [
+        "€a".dup.force_encoding(Encoding::UTF_8).to_sym,
+        "€b".dup.force_encoding(Encoding::UTF_8).to_sym
+      ]
+      Marshal.dump(value).should == "\x04\b[\a#{symbol1}#{symbol2}"
+
+      value = [*value, value[0]]
+      Marshal.dump(value).should == "\x04\b[\b#{symbol1}#{symbol2};\x00"
+    end
+
+    it "uses symbol links for objects repeatedly dumped" do
+      symbol = :foo
+      Marshal.dump([symbol, symbol]).should == "\x04\b[\a:\bfoo;\x00" # ;\x00 is a link to the symbol object
+    end
   end
 
   describe "with an object responding to #marshal_dump" do
@@ -89,17 +114,54 @@ describe "Marshal.dump" do
       UserMarshal.should_not_receive(:name)
       Marshal.dump(UserMarshal.new)
     end
+
+    it "raises TypeError if an Object is an instance of an anonymous class" do
+      -> { Marshal.dump(Class.new(UserMarshal).new) }.should.raise(TypeError, /can't dump anonymous class/)
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      obj = UserMarshal.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\aU:\x10UserMarshal:\tdata@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables of a dumped object after the object itself into the objects table" do
+      value = "<foo>"
+      obj = MarshalSpec::UserMarshalDumpWithIvar.new("string", value)
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\t, that means Integer 4)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bU:)MarshalSpec::UserMarshalDumpWithIvarI[\x06\"\vstring\x06:\t@foo\"\n<foo>@\x06@\t"
+    end
   end
 
   describe "with an object responding to #_dump" do
-    it "dumps the object returned by #marshal_dump" do
+    it "dumps the String returned by #_dump" do
       Marshal.dump(UserDefined.new).should == "\004\bu:\020UserDefined\022\004\b[\a:\nstuff;\000"
     end
 
+    it "dumps the String in non US-ASCII and non UTF-8 encoding" do
+      object = UserDefinedString.new("a".encode("windows-1251"))
+      Marshal.dump(object).should == "\x04\bIu:\x16UserDefinedString\x06a\x06:\rencoding\"\x11Windows-1251"
+    end
+
+    it "dumps the String in multibyte encoding" do
+      object = UserDefinedString.new("a".encode("utf-32le"))
+      Marshal.dump(object).should == "\x04\bIu:\x16UserDefinedString\ta\x00\x00\x00\x06:\rencoding\"\rUTF-32LE"
+    end
+
+    it "ignores overridden name method" do
+      obj = MarshalSpec::UserDefinedWithOverriddenName.new
+      Marshal.dump(obj).should == "\x04\bu:/MarshalSpec::UserDefinedWithOverriddenName\x12\x04\b[\a:\nstuff;\x00"
+    end
+
     it "raises a TypeError if _dump returns a non-string" do
       m = mock("marshaled")
       m.should_receive(:_dump).and_return(0)
-      -> { Marshal.dump(m) }.should raise_error(TypeError)
+      -> { Marshal.dump(m) }.should.raise(TypeError)
+    end
+
+    it "raises TypeError if an Object is an instance of an anonymous class" do
+      -> { Marshal.dump(Class.new(UserDefined).new) }.should.raise(TypeError, /can't dump anonymous class/)
     end
 
     it "favors marshal_dump over _dump" do
@@ -108,6 +170,48 @@ describe "Marshal.dump" do
       m.should_not_receive(:_dump)
       Marshal.dump(m)
     end
+
+    it "indexes instance variables of a String returned by #_dump at first and then indexes the object itself" do
+      class MarshalSpec::M1::A
+        def _dump(level)
+          s = +"<dump>"
+          s.instance_variable_set(:@foo, "bar")
+          s
+        end
+      end
+
+      a = MarshalSpec::M1::A.new
+
+      # 0-based index of the object a = 2, that is encoded as \x07 and printed as "\a" character.
+      # Objects are serialized in the following order: Array, a, "bar".
+      # But they are indexed in different order: Array (index=0), "bar" (index=1), a (index=2)
+      # So the second occurenc of the object a is encoded as an index 2.
+      reference = "@\a"
+      Marshal.dump([a, a]).should == "\x04\b[\aIu:\x17MarshalSpec::M1::A\v<dump>\x06:\t@foo\"\bbar#{reference}"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      obj = UserDefined.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\au:\x10UserDefined\x12\x04\b[\a:\nstuff;\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables of a dumped String before the object itself into the objects table" do
+      value = "<foo>"
+      obj = MarshalSpec::UserDefinedDumpWithIVars.new(+"string", value)
+
+      # expect a link to the object (@\a, that means Integer 2) is greater than a link
+      # to the instance variable value (@\x06, that means Integer 1)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIu:*MarshalSpec::UserDefinedDumpWithIVars\vstring\x06:\t@foo\"\n<foo>@\a@\x06"
+    end
+
+    describe "Core library classes with #_dump returning a String with instance variables" do
+      it "indexes instance variables and then a Time object itself" do
+        t = Time.utc(2022)
+        reference = "@\a"
+
+        Marshal.dump([t, t]).should == "\x04\b[\aIu:\tTime\r \x80\x1E\xC0\x00\x00\x00\x00\x06:\tzoneI\"\bUTC\x06:\x06EF#{reference}"
+      end
+    end
   end
 
   describe "with a Class" do
@@ -123,12 +227,28 @@ describe "Marshal.dump" do
       Marshal.dump(UserDefined::Nested).should == "\004\bc\030UserDefined::Nested"
     end
 
+    it "ignores overridden name method" do
+      Marshal.dump(MarshalSpec::ClassWithOverriddenName).should == "\x04\bc)MarshalSpec::ClassWithOverriddenName"
+    end
+
+    ruby_version_is "4.0" do
+      it "dumps a class with multibyte characters in name" do
+        source_object = eval("MarshalSpec::MultibyteぁあぃいClass".dup.force_encoding(Encoding::UTF_8))
+        Marshal.dump(source_object).should == "\x04\bIc,MarshalSpec::Multibyte\xE3\x81\x81\xE3\x81\x82\xE3\x81\x83\xE3\x81\x84Class\x06:\x06ET"
+        Marshal.load(Marshal.dump(source_object)) == source_object
+      end
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      Marshal.dump([String, String]).should == "\x04\b[\ac\vString@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Class" do
-      -> { Marshal.dump(Class.new) }.should raise_error(TypeError)
+      -> { Marshal.dump(Class.new) }.should.raise(TypeError, /can't dump anonymous class/)
     end
 
     it "raises TypeError with a singleton Class" do
-      -> { Marshal.dump(class << self; self end) }.should raise_error(TypeError)
+      -> { Marshal.dump(class << self; self end) }.should.raise(TypeError)
     end
   end
 
@@ -137,8 +257,24 @@ describe "Marshal.dump" do
       Marshal.dump(Marshal).should == "\004\bm\fMarshal"
     end
 
+    it "ignores overridden name method" do
+      Marshal.dump(MarshalSpec::ModuleWithOverriddenName).should == "\x04\bc*MarshalSpec::ModuleWithOverriddenName"
+    end
+
+    ruby_version_is "4.0" do
+      it "dumps a module with multibyte characters in name" do
+        source_object = eval("MarshalSpec::MultibyteけげこごModule".dup.force_encoding(Encoding::UTF_8))
+        Marshal.dump(source_object).should == "\x04\bIm-MarshalSpec::Multibyte\xE3\x81\x91\xE3\x81\x92\xE3\x81\x93\xE3\x81\x94Module\x06:\x06ET"
+        Marshal.load(Marshal.dump(source_object)) == source_object
+      end
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      Marshal.dump([Marshal, Marshal]).should == "\x04\b[\am\fMarshal@\x06" # @\x06 is a link to the object
+    end
+
     it "raises TypeError with an anonymous Module" do
-      -> { Marshal.dump(Module.new) }.should raise_error(TypeError)
+      -> { Marshal.dump(Module.new) }.should.raise(TypeError, /can't dump anonymous module/)
     end
   end
 
@@ -155,6 +291,23 @@ describe "Marshal.dump" do
         [Marshal,  nan_value,      "\004\bf\bnan"],
       ].should be_computed_by(:dump)
     end
+
+    it "may or may not use object links for objects repeatedly dumped" do
+      # it's an MRI implementation detail - on x86 architecture object links
+      # aren't used for Float values but on amd64 - object links are used
+
+      dump = Marshal.dump([0.0, 0.0])
+      ["\x04\b[\af\x060@\x06", "\x04\b[\af\x060f\x060"].should.include?(dump)
+
+      # if object links aren't used - entries in the objects table are still
+      # occupied by Float values
+      if dump == "\x04\b[\af\x060f\x060"
+        s = "string"
+        # an index of "string" ("@\b") in the object table equals 3 (`"\b".ord - 5`),
+        # so `0.0, 0,0` elements occupied indices 1 and 2
+        Marshal.dump([0.0, 0.0, s, s]).should == "\x04\b[\tf\x060f\x060\"\vstring@\b"
+      end
+    end
   end
 
   describe "with a Bignum" do
@@ -171,15 +324,81 @@ describe "Marshal.dump" do
         [Marshal, -2**64, "\004\bl-\n\000\000\000\000\000\000\000\000\001\000"],
       ].should be_computed_by(:dump)
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      n = 2**64
+      Marshal.dump([n, n]).should == "\x04\b[\al+\n\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "increases the object links counter" do
+      obj = Object.new
+      object_1_link = "\x06" # representing of (0-based) index=1 (by adding 5 for small Integers)
+      object_2_link = "\x07" # representing of index=2
+
+      # objects: Array, Object, Object
+      Marshal.dump([obj, obj]).should == "\x04\b[\ao:\vObject\x00@#{object_1_link}"
+
+      # objects: Array, Bignum, Object, Object
+      Marshal.dump([2**64, obj, obj]).should == "\x04\b[\bl+\n\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00o:\vObject\x00@#{object_2_link}"
+      Marshal.dump([2**48, obj, obj]).should == "\x04\b[\bl+\t\x00\x00\x00\x00\x00\x00\x01\x00o:\vObject\x00@#{object_2_link}"
+      Marshal.dump([2**32, obj, obj]).should == "\x04\b[\bl+\b\x00\x00\x00\x00\x01\x00o:\vObject\x00@#{object_2_link}"
+    end
+  end
+
+  describe "with a Rational" do
+    it "dumps a Rational" do
+      Marshal.dump(Rational(2, 3)).should == "\x04\bU:\rRational[\ai\ai\b"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      r = Rational(2, 3)
+      Marshal.dump([r, r]).should == "\x04\b[\aU:\rRational[\ai\ai\b@\x06" # @\x06 is a link to the object
+    end
+  end
+
+  describe "with a Complex" do
+    it "dumps a Complex" do
+      Marshal.dump(Complex(2, 3)).should == "\x04\bU:\fComplex[\ai\ai\b"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      c = Complex(2, 3)
+      Marshal.dump([c, c]).should == "\x04\b[\aU:\fComplex[\ai\ai\b@\x06" # @\x06 is a link to the object
+    end
+  end
+
+  describe "with a Data" do
+    it "dumps a Data" do
+      Marshal.dump(MarshalSpec::DataSpec::Measure.new(100, 'km')).should == "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+    end
+
+    it "dumps an extended Data" do
+      obj = MarshalSpec::DataSpec::MeasureExtended.new(100, "km")
+      Marshal.dump(obj).should == "\x04\bS:+MarshalSpec::DataSpec::MeasureExtended\a:\vamountii:\tunit\"\akm"
+    end
+
+    it "ignores overridden name method" do
+      obj = MarshalSpec::DataSpec::MeasureWithOverriddenName.new(100, "km")
+      Marshal.dump(obj).should == "\x04\bS:5MarshalSpec::DataSpec::MeasureWithOverriddenName\a:\vamountii:\tunit\"\akm"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      d = MarshalSpec::DataSpec::Measure.new(100, 'km')
+      Marshal.dump([d, d]).should == "\x04\b[\aS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm@\x06" # @\x06 is a link to the object
+    end
+
+    it "raises TypeError with an anonymous Struct" do
+      -> { Marshal.dump(Data.define(:a).new(1)) }.should.raise(TypeError, /can't dump anonymous class/)
+    end
   end
 
   describe "with a String" do
     it "dumps a blank String" do
-      Marshal.dump("".force_encoding("binary")).should == "\004\b\"\000"
+      Marshal.dump("".dup.force_encoding("binary")).should == "\004\b\"\000"
     end
 
     it "dumps a short String" do
-      Marshal.dump("short".force_encoding("binary")).should == "\004\b\"\012short"
+      Marshal.dump("short".dup.force_encoding("binary")).should == "\004\b\"\012short"
     end
 
     it "dumps a long String" do
@@ -187,7 +406,7 @@ describe "Marshal.dump" do
     end
 
     it "dumps a String extended with a Module" do
-      Marshal.dump("".extend(Meths).force_encoding("binary")).should == "\004\be:\nMeths\"\000"
+      Marshal.dump("".dup.extend(Meths).force_encoding("binary")).should == "\004\be:\nMeths\"\000"
     end
 
     it "dumps a String subclass" do
@@ -198,24 +417,29 @@ describe "Marshal.dump" do
       Marshal.dump(UserString.new.extend(Meths).force_encoding("binary")).should == "\004\be:\nMethsC:\017UserString\"\000"
     end
 
+    it "ignores overridden name method when dumps a String subclass" do
+      obj = MarshalSpec::StringWithOverriddenName.new
+      Marshal.dump(obj).should == "\x04\bC:*MarshalSpec::StringWithOverriddenName\"\x00"
+    end
+
     it "dumps a String with instance variables" do
-      str = ""
+      str = +""
       str.instance_variable_set("@foo", "bar")
       Marshal.dump(str.force_encoding("binary")).should == "\x04\bI\"\x00\x06:\t@foo\"\bbar"
     end
 
     it "dumps a US-ASCII String" do
-      str = "abc".force_encoding("us-ascii")
+      str = "abc".dup.force_encoding("us-ascii")
       Marshal.dump(str).should == "\x04\bI\"\babc\x06:\x06EF"
     end
 
     it "dumps a UTF-8 String" do
-      str = "\x6d\xc3\xb6\x68\x72\x65".force_encoding("utf-8")
+      str = "\x6d\xc3\xb6\x68\x72\x65".dup.force_encoding("utf-8")
       Marshal.dump(str).should == "\x04\bI\"\vm\xC3\xB6hre\x06:\x06ET"
     end
 
     it "dumps a String in another encoding" do
-      str = "\x6d\x00\xf6\x00\x68\x00\x72\x00\x65\x00".force_encoding("utf-16le")
+      str = "\x6d\x00\xf6\x00\x68\x00\x72\x00\x65\x00".dup.force_encoding("utf-16le")
       result = "\x04\bI\"\x0Fm\x00\xF6\x00h\x00r\x00e\x00\x06:\rencoding\"\rUTF-16LE"
       Marshal.dump(str).should == result
     end
@@ -223,6 +447,21 @@ describe "Marshal.dump" do
     it "dumps multiple strings using symlinks for the :E (encoding) symbol" do
       Marshal.dump(["".encode("us-ascii"), "".encode("utf-8")]).should == "\x04\b[\aI\"\x00\x06:\x06EFI\"\x00\x06;\x00T"
     end
+
+    it "uses object links for objects repeatedly dumped" do
+      s = "string"
+      Marshal.dump([s, s]).should == "\x04\b[\a\"\vstring@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = +"string"
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI\"\vstring\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Regexp" do
@@ -234,14 +473,26 @@ describe "Marshal.dump" do
       Marshal.dump(//im).should == "\x04\bI/\x00\x05\x06:\x06EF"
     end
 
-    it "dumps a Regexp with instance variables" do
-      o = //
+    it "dumps a Regexp subclass with instance variables" do
+      o = UserRegexp.new("")
       o.instance_variable_set(:@ivar, :ivar)
-      Marshal.dump(o).should == "\x04\bI/\x00\x00\a:\x06EF:\n@ivar:\tivar"
+      Marshal.dump(o).should == "\x04\bIC:\x0FUserRegexp/\x00\x00\a:\x06EF:\n@ivar:\tivar"
+    end
+
+    it "dumps an extended Regexp subclass" do
+      Marshal.dump(UserRegexp.new("").extend(Meths)).should == "\x04\bIe:\nMethsC:\x0FUserRegexp/\x00\x00\x06:\x06EF"
     end
 
-    it "dumps an extended Regexp" do
-      Marshal.dump(//.extend(Meths)).should == "\x04\bIe:\nMeths/\x00\x00\x06:\x06EF"
+    ruby_version_is ""..."4.1" do
+      it "dumps a Regexp with instance variables" do
+        o = Regexp.new("")
+        o.instance_variable_set(:@ivar, :ivar)
+        Marshal.dump(o).should == "\x04\bI/\x00\x00\a:\x06EF:\n@ivar:\tivar"
+      end
+
+      it "dumps an extended Regexp" do
+        Marshal.dump(Regexp.new("").extend(Meths)).should == "\x04\bIe:\nMeths/\x00\x00\x06:\x06EF"
+      end
     end
 
     it "dumps a Regexp subclass" do
@@ -249,18 +500,51 @@ describe "Marshal.dump" do
     end
 
     it "dumps a binary Regexp" do
-      o = Regexp.new("".force_encoding("binary"), Regexp::FIXEDENCODING)
+      o = Regexp.new("".dup.force_encoding("binary"), Regexp::FIXEDENCODING)
       Marshal.dump(o).should == "\x04\b/\x00\x10"
     end
 
+    it "dumps an ascii-compatible Regexp" do
+      o = Regexp.new("a".encode("us-ascii"), Regexp::FIXEDENCODING)
+      Marshal.dump(o).should == "\x04\bI/\x06a\x10\x06:\x06EF"
+
+      o = Regexp.new("a".encode("us-ascii"))
+      Marshal.dump(o).should == "\x04\bI/\x06a\x00\x06:\x06EF"
+
+      o = Regexp.new("a".encode("windows-1251"), Regexp::FIXEDENCODING)
+      Marshal.dump(o).should == "\x04\bI/\x06a\x10\x06:\rencoding\"\x11Windows-1251"
+
+      o = Regexp.new("a".encode("windows-1251"))
+      Marshal.dump(o).should == "\x04\bI/\x06a\x00\x06:\x06EF"
+    end
+
     it "dumps a UTF-8 Regexp" do
-      o = Regexp.new("".force_encoding("utf-8"), Regexp::FIXEDENCODING)
+      o = Regexp.new("".dup.force_encoding("utf-8"), Regexp::FIXEDENCODING)
       Marshal.dump(o).should == "\x04\bI/\x00\x10\x06:\x06ET"
+
+      o = Regexp.new("a".dup.force_encoding("utf-8"), Regexp::FIXEDENCODING)
+      Marshal.dump(o).should == "\x04\bI/\x06a\x10\x06:\x06ET"
+
+      o = Regexp.new("\u3042".dup.force_encoding("utf-8"), Regexp::FIXEDENCODING)
+      Marshal.dump(o).should == "\x04\bI/\b\xE3\x81\x82\x10\x06:\x06ET"
     end
 
     it "dumps a Regexp in another encoding" do
-      o = Regexp.new("".force_encoding("utf-16le"), Regexp::FIXEDENCODING)
+      o = Regexp.new("".dup.force_encoding("utf-16le"), Regexp::FIXEDENCODING)
       Marshal.dump(o).should == "\x04\bI/\x00\x10\x06:\rencoding\"\rUTF-16LE"
+
+      o = Regexp.new("a".encode("utf-16le"), Regexp::FIXEDENCODING)
+      Marshal.dump(o).should == "\x04\bI/\aa\x00\x10\x06:\rencoding\"\rUTF-16LE"
+    end
+
+    it "ignores overridden name method when dumps a Regexp subclass" do
+      obj = MarshalSpec::RegexpWithOverriddenName.new("")
+      Marshal.dump(obj).should == "\x04\bIC:*MarshalSpec::RegexpWithOverriddenName/\x00\x00\x06:\x06EF"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      r = /\A.\Z/
+      Marshal.dump([r, r]).should == "\x04\b[\aI/\n\\A.\\Z\x00\x06:\x06EF@\x06" # @\x06 is a link to the object
     end
   end
 
@@ -292,6 +576,26 @@ describe "Marshal.dump" do
     it "dumps an extended Array" do
       Marshal.dump([].extend(Meths)).should == "\004\be:\nMeths[\000"
     end
+
+    it "ignores overridden name method when dumps an Array subclass" do
+      obj = MarshalSpec::ArrayWithOverriddenName.new
+      Marshal.dump(obj).should == "\x04\bC:)MarshalSpec::ArrayWithOverriddenName[\x00"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      a = [1]
+      Marshal.dump([a, a]).should == "\x04\b[\a[\x06i\x06@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = []
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI[\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Hash" do
@@ -299,6 +603,10 @@ describe "Marshal.dump" do
       Marshal.dump({}).should == "\004\b{\000"
     end
 
+    it "dumps a non-empty Hash" do
+      Marshal.dump({a: 1}).should == "\x04\b{\x06:\x06ai\x06"
+    end
+
     it "dumps a Hash subclass" do
       Marshal.dump(UserHash.new).should == "\004\bC:\rUserHash{\000"
     end
@@ -307,8 +615,22 @@ describe "Marshal.dump" do
       Marshal.dump(Hash.new(1)).should == "\004\b}\000i\006"
     end
 
+    it "dumps a Hash with compare_by_identity" do
+      h = {}
+      h.compare_by_identity
+
+      Marshal.dump(h).should == "\004\bC:\tHash{\x00"
+    end
+
+    it "dumps a Hash subclass with compare_by_identity" do
+      h = UserHash.new
+      h.compare_by_identity
+
+      Marshal.dump(h).should == "\x04\bC:\rUserHashC:\tHash{\x00"
+    end
+
     it "raises a TypeError with hash having default proc" do
-      -> { Marshal.dump(Hash.new {}) }.should raise_error(TypeError)
+      -> { Marshal.dump(Hash.new {}) }.should.raise(TypeError, "can't dump hash with default proc")
     end
 
     it "dumps a Hash with instance variables" do
@@ -324,6 +646,26 @@ describe "Marshal.dump" do
     it "dumps an Hash subclass with a parameter to initialize" do
       Marshal.dump(UserHashInitParams.new(1)).should == "\004\bIC:\027UserHashInitParams{\000\006:\a@ai\006"
     end
+
+    it "ignores overridden name method when dumps a Hash subclass" do
+      obj = MarshalSpec::HashWithOverriddenName.new
+      Marshal.dump(obj).should == "\x04\bC:(MarshalSpec::HashWithOverriddenName{\x00"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      h = {a: 1}
+      Marshal.dump([h, h]).should == "\x04\b[\a{\x06:\x06ai\x06@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = {}
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bI{\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Struct" do
@@ -343,10 +685,39 @@ describe "Marshal.dump" do
     end
 
     it "dumps an extended Struct" do
-      st = Struct.new("Extended", :a, :b).new
-      Marshal.dump(st.extend(Meths)).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+      obj = Struct.new("Extended", :a, :b).new.extend(Meths)
+      Marshal.dump(obj).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+
+      s = 'hi'
+      obj.a = [:a, s]
+      obj.b = [:Meths, s]
+      Marshal.dump(obj).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
       Struct.send(:remove_const, :Extended)
     end
+
+    it "ignores overridden name method" do
+      obj = MarshalSpec::StructWithOverriddenName.new("member")
+      Marshal.dump(obj).should == "\x04\bS:*MarshalSpec::StructWithOverriddenName\x06:\x06a\"\vmember"
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      s = Struct::Pyramid.new
+      Marshal.dump([s, s]).should == "\x04\b[\aS:\x14Struct::Pyramid\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "raises TypeError with an anonymous Struct" do
+      -> { Marshal.dump(Struct.new(:a).new(1)) }.should.raise(TypeError, /can't dump anonymous class/)
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Struct::Pyramid.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIS:\x14Struct::Pyramid\x00\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with an Object" do
@@ -366,7 +737,7 @@ describe "Marshal.dump" do
 
     it "dumps an Object with a non-US-ASCII instance variable" do
       obj = Object.new
-      ivar = "@é".force_encoding(Encoding::UTF_8).to_sym
+      ivar = "@é".dup.force_encoding(Encoding::UTF_8).to_sym
       obj.instance_variable_set(ivar, 1)
       Marshal.dump(obj).should == "\x04\bo:\vObject\x06I:\b@\xC3\xA9\x06:\x06ETi\x06"
     end
@@ -378,46 +749,105 @@ describe "Marshal.dump" do
       Marshal.dump(obj).should == "\004\bo:\x0BObject\x00"
     end
 
-    it "dumps an Object if it has a singleton class but no singleton methods" do
+    it "dumps an Object if it has a singleton class but no singleton methods and no singleton instance variables" do
       obj = Object.new
       obj.singleton_class
       Marshal.dump(obj).should == "\004\bo:\x0BObject\x00"
     end
 
-    it "raises if an Object has a singleton class and singleton methods" do
+    it "ignores overridden name method" do
+      obj = MarshalSpec::ClassWithOverriddenName.new
+      Marshal.dump(obj).should == "\x04\bo:)MarshalSpec::ClassWithOverriddenName\x00"
+    end
+
+    it "raises TypeError if an Object has a singleton class and singleton methods" do
       obj = Object.new
       def obj.foo; end
       -> {
         Marshal.dump(obj)
-      }.should raise_error(TypeError, "singleton can't be dumped")
+      }.should.raise(TypeError, "singleton can't be dumped")
+    end
+
+    it "raises TypeError if an Object has a singleton class and singleton instance variables" do
+      obj = Object.new
+      class << obj
+        @v = 1
+      end
+
+      -> {
+        Marshal.dump(obj)
+      }.should.raise(TypeError, "singleton can't be dumped")
+    end
+
+    it "raises TypeError if an Object is an instance of an anonymous class" do
+      anonymous_class = Class.new
+      obj = anonymous_class.new
+
+      -> { Marshal.dump(obj) }.should.raise(TypeError, /can't dump anonymous class/)
+    end
+
+    it "raises TypeError if an Object extends an anonymous module" do
+      anonymous_module = Module.new
+      obj = Object.new
+      obj.extend(anonymous_module)
+
+      -> { Marshal.dump(obj) }.should.raise(TypeError, /can't dump anonymous class/)
     end
 
     it "dumps a BasicObject subclass if it defines respond_to?" do
       obj = MarshalSpec::BasicObjectSubWithRespondToFalse.new
       Marshal.dump(obj).should == "\x04\bo:2MarshalSpec::BasicObjectSubWithRespondToFalse\x00"
     end
+
+    it "dumps without marshaling any attached finalizer" do
+      obj = Object.new
+      finalizer = Object.new
+      def finalizer.noop(_)
+      end
+      ObjectSpace.define_finalizer(obj, finalizer.method(:noop))
+      Marshal.load(Marshal.dump(obj)).class.should == Object
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      obj = Object.new
+      Marshal.dump([obj, obj]).should == "\x04\b[\ao:\vObject\x00@\x06" # @\x06 is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Object.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bo:\vObject\x06:\t@foo\"\n<foo>@\x06@\a"
+    end
   end
 
   describe "with a Range" do
-    it "dumps a Range inclusive of end (with indeterminant order)" do
+    it "dumps a Range inclusive of end" do
       dump = Marshal.dump(1..2)
+      dump.should == "\x04\bo:\nRange\b:\texclF:\nbegini\x06:\bendi\a"
+
       load = Marshal.load(dump)
       load.should == (1..2)
     end
 
-    it "dumps a Range exclusive of end (with indeterminant order)" do
+    it "dumps a Range exclusive of end" do
       dump = Marshal.dump(1...2)
+      dump.should == "\x04\bo:\nRange\b:\texclT:\nbegini\x06:\bendi\a"
+
       load = Marshal.load(dump)
       load.should == (1...2)
     end
 
-    it "dumps a Range with extra instance variables" do
-      range = (1...3)
-      range.instance_variable_set :@foo, 42
-      dump = Marshal.dump(range)
-      load = Marshal.load(dump)
-      load.should == range
-      load.instance_variable_get(:@foo).should == 42
+    it "uses object links for objects repeatedly dumped" do
+      r = 1..2
+      Marshal.dump([r, r]).should == "\x04\b[\ao:\nRange\b:\texclF:\nbegini\x06:\bendi\a@\x06" # @\x06 is a link to the object
+    end
+
+    it "raises TypeError with an anonymous Range subclass" do
+      -> { Marshal.dump(Class.new(Range).new(1, 2)) }.should.raise(TypeError, /can't dump anonymous class/)
     end
   end
 
@@ -447,7 +877,7 @@ describe "Marshal.dump" do
         base = "\x04\bIu:\tTime\r#{@t_dump}\a"
         offset = ":\voffseti\x020*"
         zone = ":\tzoneI\"\bAST\x06:\x06EF" # Last is 'F' (US-ASCII)
-        [ "#{base}#{offset}#{zone}", "#{base}#{zone}#{offset}" ].should include(dump)
+        [ "#{base}#{offset}#{zone}", "#{base}#{zone}#{offset}" ].should.include?(dump)
       end
     end
 
@@ -456,6 +886,43 @@ describe "Marshal.dump" do
       zone = ":\tzoneI\"\bUTC\x06:\x06EF" # Last is 'F' (US-ASCII)
       dump.should == "\x04\bIu:\tTime\r#{@utc_dump}\x06#{zone}"
     end
+
+    it "ignores overridden name method" do
+      obj = MarshalSpec::TimeWithOverriddenName.new
+      Marshal.dump(obj).should.include?("MarshalSpec::TimeWithOverriddenName")
+    end
+
+    ruby_version_is "4.0" do
+      it "dumps a Time subclass with multibyte characters in name" do
+        source_object = eval("MarshalSpec::MultibyteぁあぃいTime".dup.force_encoding(Encoding::UTF_8))
+        Marshal.dump(source_object).should == "\x04\bIc+MarshalSpec::Multibyte\xE3\x81\x81\xE3\x81\x82\xE3\x81\x83\xE3\x81\x84Time\x06:\x06ET"
+        Marshal.load(Marshal.dump(source_object)) == source_object
+      end
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      # order of the offset and zone instance variables is a subject to change
+      # and may be different on different CRuby versions
+      base = Regexp.quote("\x04\b[\aIu:\tTime\r\xF5\xEF\e\x80\x00\x00\x00\x00\a")
+      offset = Regexp.quote(":\voffseti\x020*:\tzoneI\"\bAST\x06:\x06EF")
+      zone = Regexp.quote(":\tzoneI\"\bAST\x06:\x06EF:\voffseti\x020*")
+      instance_variables = /#{offset}|#{zone}/
+      Marshal.dump([@t, @t]).should =~ /\A#{base}#{instance_variables}@\a\Z/ # @\a is a link to the object
+    end
+
+    it "adds instance variables before the object itself into the objects table" do
+      obj = @utc
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\b, that means Integer 3) is greater than a link
+      # to the instance variable value (@\x06, that means Integer 1)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bIu:\tTime\r \x00\x1C\xC0\x00\x00\x00\x00\a:\t@foo\"\n<foo>:\tzoneI\"\bUTC\x06:\x06EF@\b@\x06"
+    end
+
+    it "raises TypeError with an anonymous Time subclass" do
+      -> { Marshal.dump(Class.new(Time).now) }.should.raise(TypeError)
+    end
   end
 
   describe "with an Exception" do
@@ -473,6 +940,12 @@ describe "Marshal.dump" do
       Marshal.dump(obj).should == "\x04\bo:\x0EException\a:\tmesg\"\bfoo:\abt[\x06\"\x12foo/bar.rb:10"
     end
 
+    it "dumps instance variables if they exist" do
+      obj = Exception.new("foo")
+      obj.instance_variable_set(:@ivar, 1)
+      Marshal.dump(obj).should == "\x04\bo:\x0EException\b:\tmesg\"\bfoo:\abt0:\n@ivari\x06"
+    end
+
     it "dumps the cause for the exception" do
       exc = nil
       begin
@@ -481,15 +954,47 @@ describe "Marshal.dump" do
         begin
           raise RuntimeError, "the consequence"
         rescue RuntimeError => e
-          e.cause.should equal(cause)
+          e.cause.should.equal?(cause)
           exc = e
         end
       end
 
       reloaded = Marshal.load(Marshal.dump(exc))
-      reloaded.cause.should be_an_instance_of(StandardError)
+      reloaded.cause.should.instance_of?(StandardError)
       reloaded.cause.message.should == "the cause"
     end
+
+    # NoMethodError uses an exception formatter on TruffleRuby and computes a message lazily
+    it "dumps the message for the raised NoMethodError exception" do
+      begin
+        "".foo
+      rescue => e
+      end
+
+      Marshal.dump(e).should =~ /undefined method [`']foo' for ("":String|an instance of String)/
+    end
+
+    it "uses object links for objects repeatedly dumped" do
+      e = Exception.new
+      Marshal.dump([e, e]).should == "\x04\b[\ao:\x0EException\a:\tmesg0:\abt0@\x06" # @\x\a is a link to the object
+    end
+
+    it "adds instance variables after the object itself into the objects table" do
+      obj = Exception.new
+      value = "<foo>"
+      obj.instance_variable_set :@foo, value
+
+      # expect a link to the object (@\x06, that means Integer 1) is smaller than a link
+      # to the instance variable value (@\a, that means Integer 2)
+      Marshal.dump([obj, obj, value]).should == "\x04\b[\bo:\x0EException\b:\tmesg0:\abt0:\t@foo\"\n<foo>@\x06@\a"
+    end
+
+    it "raises TypeError if an Object is an instance of an anonymous class" do
+      anonymous_class = Class.new(Exception)
+      obj = anonymous_class.new
+
+      -> { Marshal.dump(obj) }.should.raise(TypeError, /can't dump anonymous class/)
+    end
   end
 
   it "dumps subsequent appearances of a symbol as a link" do
@@ -509,10 +1014,10 @@ describe "Marshal.dump" do
 
   it "raises an ArgumentError when the recursion limit is exceeded" do
     h = {'one' => {'two' => {'three' => 0}}}
-    -> { Marshal.dump(h, 3) }.should raise_error(ArgumentError)
-    -> { Marshal.dump([h], 4) }.should raise_error(ArgumentError)
-    -> { Marshal.dump([], 0) }.should raise_error(ArgumentError)
-    -> { Marshal.dump([[[]]], 1) }.should raise_error(ArgumentError)
+    -> { Marshal.dump(h, 3) }.should.raise(ArgumentError)
+    -> { Marshal.dump([h], 4) }.should.raise(ArgumentError)
+    -> { Marshal.dump([], 0) }.should.raise(ArgumentError)
+    -> { Marshal.dump([[[]]], 1) }.should.raise(ArgumentError)
   end
 
   it "ignores the recursion limit if the limit is negative" do
@@ -522,7 +1027,6 @@ describe "Marshal.dump" do
   end
 
   describe "when passed an IO" do
-
     it "writes the serialized data to the IO-Object" do
       (obj = mock('test')).should_receive(:write).at_least(1)
       Marshal.dump("test", obj)
@@ -535,7 +1039,7 @@ describe "Marshal.dump" do
 
     it "raises an Error when the IO-Object does not respond to #write" do
       obj = mock('test')
-      -> { Marshal.dump("test", obj) }.should raise_error(TypeError)
+      -> { Marshal.dump("test", obj) }.should.raise(TypeError)
     end
 
 
@@ -545,63 +1049,34 @@ describe "Marshal.dump" do
       obj.should_receive(:binmode).at_least(1)
       Marshal.dump("test", obj)
     end
-
-
   end
 
   describe "when passed a StringIO" do
-
     it "should raise an error" do
       require "stringio"
-
-      -> { Marshal.dump(StringIO.new) }.should raise_error(TypeError)
+      -> { Marshal.dump(StringIO.new) }.should.raise(TypeError)
     end
-
   end
 
   it "raises a TypeError if marshalling a Method instance" do
-    -> { Marshal.dump(Marshal.method(:dump)) }.should raise_error(TypeError)
+    -> { Marshal.dump(Marshal.method(:dump)) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if marshalling a Proc" do
-    -> { Marshal.dump(proc {}) }.should raise_error(TypeError)
+    -> { Marshal.dump(proc {}) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if dumping a IO/File instance" do
-    -> { Marshal.dump(STDIN) }.should raise_error(TypeError)
-    -> { File.open(__FILE__) { |f| Marshal.dump(f) } }.should raise_error(TypeError)
+    -> { Marshal.dump(STDIN) }.should.raise(TypeError)
+    -> { File.open(__FILE__) { |f| Marshal.dump(f) } }.should.raise(TypeError)
   end
 
   it "raises a TypeError if dumping a MatchData instance" do
-    -> { Marshal.dump(/(.)/.match("foo")) }.should raise_error(TypeError)
+    -> { Marshal.dump(/(.)/.match("foo")) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if dumping a Mutex instance" do
     m = Mutex.new
-    -> { Marshal.dump(m) }.should raise_error(TypeError)
-  end
-
-  it "returns an untainted string if object is untainted" do
-    Marshal.dump(Object.new).tainted?.should be_false
-  end
-
-  it "returns a tainted string if object is tainted" do
-    Marshal.dump(Object.new.taint).tainted?.should be_true
-  end
-
-  it "returns a tainted string if nested object is tainted" do
-    Marshal.dump([[Object.new.taint]]).tainted?.should be_true
-  end
-
-  it "returns a trusted string if object is trusted" do
-    Marshal.dump(Object.new).untrusted?.should be_false
-  end
-
-  it "returns an untrusted string if object is untrusted" do
-    Marshal.dump(Object.new.untrust).untrusted?.should be_true
-  end
-
-  it "returns an untrusted string if nested object is untrusted" do
-    Marshal.dump([[Object.new.untrust]]).untrusted?.should be_true
+    -> { Marshal.dump(m) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/marshal/fixtures/classes.rb b/spec/ruby/core/marshal/fixtures/classes.rb
new file mode 100644
index 0000000000..7c81c64927
--- /dev/null
+++ b/spec/ruby/core/marshal/fixtures/classes.rb
@@ -0,0 +1,4 @@
+module MarshalSpec
+  # empty modules
+  module M1 end
+end
diff --git a/spec/ruby/core/marshal/fixtures/marshal_data.rb b/spec/ruby/core/marshal/fixtures/marshal_data.rb
index 2931278290..c16d9e4bb6 100644
--- a/spec/ruby/core/marshal/fixtures/marshal_data.rb
+++ b/spec/ruby/core/marshal/fixtures/marshal_data.rb
@@ -1,4 +1,7 @@
-# -*- encoding: binary -*-
+# encoding: binary
+
+require_relative 'marshal_multibyte_data'
+
 class UserDefined
   class Nested
     def ==(other)
@@ -38,7 +41,7 @@ class UserDefinedWithIvar
   attr_reader :a, :b, :c
 
   def initialize
-    @a = 'stuff'
+    @a = +'stuff'
     @a.instance_variable_set :@foo, :UserDefinedWithIvar
     @b = 'more'
     @c = @b
@@ -78,12 +81,47 @@ class UserDefinedImmediate
   end
 end
 
+class UserDefinedString
+  attr_reader :string
+
+  def initialize(string)
+    @string = string
+  end
+
+  def _dump(depth)
+    @string
+  end
+
+  def self._load(data)
+    new(data)
+  end
+end
+
+module MarshalSpec
+  class UserDefinedDumpWithIVars
+    attr_reader :string
+
+    def initialize(string, ivar_value)
+      @string = string
+      @string.instance_variable_set(:@foo, ivar_value)
+    end
+
+    def _dump(depth)
+      @string
+    end
+
+    def self._load(data)
+      new(data)
+    end
+  end
+end
+
 class UserPreviouslyDefinedWithInitializedIvar
   attr_accessor :field1, :field2
 end
 
 class UserMarshal
-  attr_reader :data
+  attr_accessor :data
 
   def initialize
     @data = 'stuff'
@@ -120,6 +158,32 @@ class UserMarshalWithIvar
   end
 end
 
+module MarshalSpec
+  class UserMarshalDumpWithIvar
+    attr_reader :data
+
+    def initialize(data, ivar_value)
+      @data = data
+      @ivar_value = ivar_value
+    end
+
+    def marshal_dump
+      obj = [data]
+      obj.instance_variable_set(:@foo, @ivar_value)
+      obj
+    end
+
+    def marshal_load(o)
+      @data = o[0]
+    end
+
+    def ==(other)
+      self.class === other and
+        @data = other.data
+    end
+  end
+end
+
 class UserArray < Array
 end
 
@@ -167,12 +231,17 @@ module MarshalSpec
     end
   end
 
+  StructToDump = Struct.new(:a, :b)
+
   class BasicObjectSubWithRespondToFalse < BasicObject
     def respond_to?(method_name, include_all=false)
       false
     end
   end
 
+  module ModuleToExtendBy
+  end
+
   def self.random_data
     randomizer = Random.new(42)
     1000.times{randomizer.rand} # Make sure we exhaust his first state of 624 random words
@@ -192,6 +261,70 @@ module MarshalSpec
     set_swapped_class(nil)
   end
 
+  class ClassWithOverriddenName
+    def self.name
+      "Foo"
+    end
+  end
+
+  class ModuleWithOverriddenName
+    def self.name
+      "Foo"
+    end
+  end
+
+  class TimeWithOverriddenName < Time
+    def self.name
+      "Foo"
+    end
+  end
+
+  class StructWithOverriddenName < Struct.new(:a)
+    def self.name
+      "Foo"
+    end
+  end
+
+  class UserDefinedWithOverriddenName < UserDefined
+    def self.name
+      "Foo"
+    end
+  end
+
+  class StringWithOverriddenName < String
+    def self.name
+      "Foo"
+    end
+  end
+
+  class ArrayWithOverriddenName < Array
+    def self.name
+      "Foo"
+    end
+  end
+
+  class HashWithOverriddenName < Hash
+    def self.name
+      "Foo"
+    end
+  end
+
+  class RegexpWithOverriddenName < Regexp
+    def self.name
+      "Foo"
+    end
+  end
+
+  class ObjectWithFreezeRaisingException < Object
+    def freeze
+      raise
+    end
+  end
+
+  class ObjectWithoutFreeze < Object
+    undef freeze
+  end
+
   DATA = {
     "nil" => [nil, "\004\b0"],
     "1..2" => [(1..2),
@@ -217,7 +350,7 @@ module MarshalSpec
                        "\004\b\"\012small"],
     "String big" => ['big' * 100,
                      "\004\b\"\002,\001#{'big' * 100}"],
-    "String extended" => [''.extend(Meths), # TODO: check for module on load
+    "String extended" => [''.dup.extend(Meths), # TODO: check for module on load
                           "\004\be:\nMeths\"\000"],
     "String subclass" => [UserString.new,
                           "\004\bC:\017UserString\"\000"],
@@ -227,36 +360,36 @@ module MarshalSpec
                        "\004\b:\010big"],
     "Symbol big" => [('big' * 100).to_sym,
                                "\004\b:\002,\001#{'big' * 100}"],
-    "Bignum -2**64" => [-2**64,
+    "Integer -2**64" => [-2**64,
                         "\004\bl-\n\000\000\000\000\000\000\000\000\001\000"],
-    "Bignum -2**63" => [-2**63,
+    "Integer -2**63" => [-2**63,
                         "\004\bl-\t\000\000\000\000\000\000\000\200"],
-    "Fixnum -2**24" => [-2**24,
+    "Integer -2**24" => [-2**24,
                         "\004\bi\375\000\000\000"],
-    "Fixnum -4516727" => [-4516727,
+    "Integer -4516727" => [-4516727,
                           "\004\bi\375\211\024\273"],
-    "Fixnum -2**16" => [-2**16,
+    "Integer -2**16" => [-2**16,
                         "\004\bi\376\000\000"],
-    "Fixnum -2**8" => [-2**8,
+    "Integer -2**8" => [-2**8,
                        "\004\bi\377\000"],
-    "Fixnum -123" => [-123,
+    "Integer -123" => [-123,
                       "\004\bi\200"],
-    "Fixnum -124" => [-124, "\004\bi\377\204"],
-    "Fixnum 0" => [0,
+    "Integer -124" => [-124, "\004\bi\377\204"],
+    "Integer 0" => [0,
                    "\004\bi\000"],
-    "Fixnum 5" => [5,
+    "Integer 5" => [5,
                    "\004\bi\n"],
-    "Fixnum 122" => [122, "\004\bi\177"],
-    "Fixnum 123" => [123, "\004\bi\001{"],
-    "Fixnum 2**8" => [2**8,
+    "Integer 122" => [122, "\004\bi\177"],
+    "Integer 123" => [123, "\004\bi\001{"],
+    "Integer 2**8" => [2**8,
                       "\004\bi\002\000\001"],
-    "Fixnum 2**16" => [2**16,
+    "Integer 2**16" => [2**16,
                        "\004\bi\003\000\000\001"],
-    "Fixnum 2**24" => [2**24,
+    "Integer 2**24" => [2**24,
                        "\004\bi\004\000\000\000\001"],
-    "Bignum 2**64" => [2**64,
+    "Integer 2**64" => [2**64,
                        "\004\bl+\n\000\000\000\000\000\000\000\000\001\000"],
-    "Bignum 2**90" => [2**90,
+    "Integer 2**90" => [2**90,
                        "\004\bl+\v#{"\000" * 11}\004"],
     "Class String" => [String,
                        "\004\bc\vString"],
@@ -324,7 +457,7 @@ module MarshalSpec
                     "\x04\bI\"\nsmall\x06:\x06EF"],
     "String big" => ['big' * 100,
                     "\x04\bI\"\x02,\x01bigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbigbig\x06:\x06EF"],
-    "String extended" => [''.extend(Meths), # TODO: check for module on load
+    "String extended" => [''.dup.extend(Meths), # TODO: check for module on load
                           "\x04\bIe:\nMeths\"\x00\x06:\x06EF"],
     "String subclass" => [UserString.new,
                           "\004\bC:\017UserString\"\000"],
@@ -334,31 +467,31 @@ module MarshalSpec
                        "\004\b:\010big"],
     "Symbol big" => [('big' * 100).to_sym,
                                "\004\b:\002,\001#{'big' * 100}"],
-    "Bignum -2**64" => [-2**64,
+    "Integer -2**64" => [-2**64,
                         "\004\bl-\n\000\000\000\000\000\000\000\000\001\000"],
-    "Bignum -2**63" => [-2**63,
+    "Integer -2**63" => [-2**63,
                         "\004\bl-\t\000\000\000\000\000\000\000\200"],
-    "Fixnum -2**24" => [-2**24,
+    "Integer -2**24" => [-2**24,
                         "\004\bi\375\000\000\000"],
-    "Fixnum -2**16" => [-2**16,
+    "Integer -2**16" => [-2**16,
                         "\004\bi\376\000\000"],
-    "Fixnum -2**8" => [-2**8,
+    "Integer -2**8" => [-2**8,
                        "\004\bi\377\000"],
-    "Fixnum -123" => [-123,
+    "Integer -123" => [-123,
                       "\004\bi\200"],
-    "Fixnum 0" => [0,
+    "Integer 0" => [0,
                    "\004\bi\000"],
-    "Fixnum 5" => [5,
+    "Integer 5" => [5,
                    "\004\bi\n"],
-    "Fixnum 2**8" => [2**8,
+    "Integer 2**8" => [2**8,
                       "\004\bi\002\000\001"],
-    "Fixnum 2**16" => [2**16,
+    "Integer 2**16" => [2**16,
                        "\004\bi\003\000\000\001"],
-    "Fixnum 2**24" => [2**24,
+    "Integer 2**24" => [2**24,
                        "\004\bi\004\000\000\000\001"],
-    "Bignum 2**64" => [2**64,
+    "Integer 2**64" => [2**64,
                        "\004\bl+\n\000\000\000\000\000\000\000\000\001\000"],
-    "Bignum 2**90" => [2**90,
+    "Integer 2**90" => [2**90,
                        "\004\bl+\v#{"\000" * 11}\004"],
     "Class String" => [String,
                        "\004\bc\vString"],
@@ -398,6 +531,20 @@ module MarshalSpec
                  "\004\bS:\024Struct::Pyramid\000"],
     "Random" => random_data,
   }
+
+  module DataSpec
+    Measure = Data.define(:amount, :unit)
+    Empty = Data.define
+
+    MeasureExtended = Class.new(Measure)
+    MeasureExtended.extend(Enumerable)
+
+    class MeasureWithOverriddenName < Measure
+      def self.name
+        "Foo"
+      end
+    end
+  end
 end
 
 class ArraySub < Array
diff --git a/spec/ruby/core/marshal/fixtures/marshal_multibyte_data.rb b/spec/ruby/core/marshal/fixtures/marshal_multibyte_data.rb
new file mode 100644
index 0000000000..98a0d43392
--- /dev/null
+++ b/spec/ruby/core/marshal/fixtures/marshal_multibyte_data.rb
@@ -0,0 +1,12 @@
+# -*- encoding: utf-8 -*-
+
+module MarshalSpec
+  class MultibyteぁあぃいClass
+  end
+
+  module MultibyteけげこごModule
+  end
+
+  class MultibyteぁあぃいTime < Time
+  end
+end
diff --git a/spec/ruby/core/marshal/float_spec.rb b/spec/ruby/core/marshal/float_spec.rb
index 5793bbd564..5b2d68d6e1 100644
--- a/spec/ruby/core/marshal/float_spec.rb
+++ b/spec/ruby/core/marshal/float_spec.rb
@@ -40,7 +40,7 @@ end
 
 describe "Marshal.load with Float" do
   it "loads NaN" do
-    Marshal.load("\004\bf\bnan").should be_nan
+    Marshal.load("\004\bf\bnan").should.nan?
   end
 
   it "loads +Infinity" do
diff --git a/spec/ruby/core/marshal/shared/load.rb b/spec/ruby/core/marshal/shared/load.rb
index f92d49c68c..02c8e7f0b1 100644
--- a/spec/ruby/core/marshal/shared/load.rb
+++ b/spec/ruby/core/marshal/shared/load.rb
@@ -1,6 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../fixtures/marshal_data'
-require 'stringio'
 
 describe :marshal_load, shared: true do
   before :all do
@@ -9,7 +8,11 @@ describe :marshal_load, shared: true do
 
   it "raises an ArgumentError when the dumped data is truncated" do
     obj = {first: 1, second: 2, third: 3}
-    -> { Marshal.send(@method, Marshal.dump(obj)[0, 5]) }.should raise_error(ArgumentError)
+    -> { Marshal.send(@method, Marshal.dump(obj)[0, 5]) }.should.raise(ArgumentError, "marshal data too short")
+  end
+
+  it "raises an ArgumentError when the argument is empty String" do
+    -> { Marshal.send(@method, "") }.should.raise(ArgumentError, "marshal data too short")
   end
 
   it "raises an ArgumentError when the dumped class is missing" do
@@ -17,10 +20,227 @@ describe :marshal_load, shared: true do
     kaboom = Marshal.dump(KaBoom.new)
     Object.send(:remove_const, :KaBoom)
 
-    -> { Marshal.send(@method, kaboom) }.should raise_error(ArgumentError)
+    -> { Marshal.send(@method, kaboom) }.should.raise(ArgumentError)
+  end
+
+  describe "when called with freeze: true" do
+    it "returns frozen strings" do
+      string = Marshal.send(@method, Marshal.dump("foo"), freeze: true)
+      string.should == "foo"
+      string.should.frozen?
+
+      utf8_string = "foo".encode(Encoding::UTF_8)
+      string = Marshal.send(@method, Marshal.dump(utf8_string), freeze: true)
+      string.should == utf8_string
+      string.should.frozen?
+    end
+
+    it "returns frozen arrays" do
+      array = Marshal.send(@method, Marshal.dump([1, 2, 3]), freeze: true)
+      array.should == [1, 2, 3]
+      array.should.frozen?
+    end
+
+    it "returns frozen hashes" do
+      hash = Marshal.send(@method, Marshal.dump({foo: 42}), freeze: true)
+      hash.should == {foo: 42}
+      hash.should.frozen?
+    end
+
+    it "returns frozen regexps" do
+      regexp = Marshal.send(@method, Marshal.dump(/foo/), freeze: true)
+      regexp.should == /foo/
+      regexp.should.frozen?
+    end
+
+    it "returns frozen structs" do
+      struct = Marshal.send(@method, Marshal.dump(MarshalSpec::StructToDump.new(1, 2)), freeze: true)
+      struct.should == MarshalSpec::StructToDump.new(1, 2)
+      struct.should.frozen?
+    end
+
+    it "returns frozen objects" do
+      source_object = Object.new
+
+      object = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+      object.should.frozen?
+    end
+
+    describe "deep freezing" do
+      it "returns hashes with frozen keys and values" do
+        key = Object.new
+        value = Object.new
+        source_object = {key => value}
+
+        hash = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+        hash.size.should == 1
+        hash.keys[0].should.frozen?
+        hash.values[0].should.frozen?
+      end
+
+      it "returns arrays with frozen elements" do
+        object = Object.new
+        source_object = [object]
+
+        array = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+        array.size.should == 1
+        array[0].should.frozen?
+      end
+
+      it "returns structs with frozen members" do
+        object1 = Object.new
+        object2 = Object.new
+        source_object = MarshalSpec::StructToDump.new(object1, object2)
+
+        struct = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+        struct.a.should.frozen?
+        struct.b.should.frozen?
+      end
+
+      it "returns objects with frozen instance variables" do
+        source_object = Object.new
+        instance_variable = Object.new
+        source_object.instance_variable_set(:@a, instance_variable)
+
+        object = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+        object.instance_variable_get(:@a).should != nil
+        object.instance_variable_get(:@a).should.frozen?
+      end
+
+      it "deduplicates frozen strings" do
+        source_object = ["foo" + "bar", "foobar"]
+        object = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+
+        object[0].should.equal?(object[1])
+      end
+    end
+
+    it "does not freeze modules" do
+      object = Marshal.send(@method, Marshal.dump(Kernel), freeze: true)
+      object.should_not.frozen?
+      Kernel.should_not.frozen?
+    end
+
+    it "does not freeze classes" do
+      object = Marshal.send(@method, Marshal.dump(Object), freeze: true)
+      object.should_not.frozen?
+      Object.should_not.frozen?
+    end
+
+    it "does freeze extended objects" do
+      object = Marshal.load("\x04\be:\x0FEnumerableo:\vObject\x00", freeze: true)
+      object.should.frozen?
+    end
+
+    it "does freeze extended objects with instance variables" do
+      object = Marshal.load("\x04\be:\x0FEnumerableo:\vObject\x06:\n@ivarT", freeze: true)
+      object.should.frozen?
+    end
+
+    it "returns frozen object having #_dump method" do
+      object = Marshal.send(@method, Marshal.dump(UserDefined.new), freeze: true)
+      object.should.frozen?
+    end
+
+    it "returns frozen object responding to #marshal_dump and #marshal_load" do
+      object = Marshal.send(@method, Marshal.dump(UserMarshal.new), freeze: true)
+      object.should.frozen?
+    end
+
+    it "returns frozen object extended by a module" do
+      object = Object.new
+      object.extend(MarshalSpec::ModuleToExtendBy)
+
+      object = Marshal.send(@method, Marshal.dump(object), freeze: true)
+      object.should.frozen?
+    end
+
+    it "does not call freeze method" do
+      object = MarshalSpec::ObjectWithFreezeRaisingException.new
+      object = Marshal.send(@method, Marshal.dump(object), freeze: true)
+      object.should.frozen?
+    end
+
+    it "returns frozen object even if object does not respond to freeze method" do
+      object = MarshalSpec::ObjectWithoutFreeze.new
+      object = Marshal.send(@method, Marshal.dump(object), freeze: true)
+      object.should.frozen?
+    end
+
+    it "returns a frozen object when is an instance of String/Array/Regexp/Hash subclass and has instance variables" do
+      source_object = UserString.new
+      source_object.instance_variable_set(:@foo, "bar")
+
+      object = Marshal.send(@method, Marshal.dump(source_object), freeze: true)
+      object.should.frozen?
+    end
+
+    describe "when called with a proc" do
+      it "call the proc with frozen objects" do
+        arr = []
+        s = +'hi'
+        s.instance_variable_set(:@foo, 5)
+        st = Struct.new("Brittle", :a).new
+        st.instance_variable_set(:@clue, 'none')
+        st.a = 0.0
+        h = Hash.new('def')
+        h['nine'] = 9
+        a = [:a, :b, :c]
+        a.instance_variable_set(:@two, 2)
+        obj = [s, 10, s, s, st, a]
+        obj.instance_variable_set(:@zoo, 'ant')
+        proc = Proc.new { |o| arr << o; o}
+
+        Marshal.send(
+          @method,
+          "\x04\bI[\vI\"\ahi\a:\x06EF:\t@fooi\ni\x0F@\x06@\x06IS:\x14Struct::Brittle\x06:\x06af\x060\x06:\n@clueI\"\tnone\x06;\x00FI[\b;\b:\x06b:\x06c\x06:\t@twoi\a\x06:\t@zooI\"\bant\x06;\x00F",
+          proc,
+          freeze: true,
+        )
+
+        arr.should == [
+          false, 5, "hi", 10, "hi", "hi", 0.0, false, "none", st,
+          :b, :c, 2, a, false, "ant", ["hi", 10, "hi", "hi", st, [:a, :b, :c]],
+        ]
+
+        arr.each do |v|
+          v.should.frozen?
+        end
+
+        Struct.send(:remove_const, :Brittle)
+      end
+
+      it "does not freeze the object returned by the proc" do
+        string = Marshal.send(@method, Marshal.dump("foo"), proc { |o| o.upcase }, freeze: true)
+        string.should == "FOO"
+        string.should_not.frozen?
+      end
+    end
   end
 
   describe "when called with a proc" do
+    it "call the proc with fully initialized strings" do
+      utf8_string = "foo".encode(Encoding::UTF_8)
+      Marshal.send(@method, Marshal.dump(utf8_string), proc { |arg|
+        if arg.is_a?(String)
+          arg.should == utf8_string
+          arg.encoding.should == Encoding::UTF_8
+        end
+        arg
+      })
+    end
+
+    it "no longer mutate the object after it was passed to the proc" do
+      string = Marshal.load(Marshal.dump("foo"), :freeze.to_proc)
+      string.should.frozen?
+    end
+
+    it "call the proc with extended objects" do
+      objs = []
+      obj = Marshal.load("\x04\be:\x0FEnumerableo:\vObject\x00", Proc.new { |o| objs << o; o })
+      objs.should == [obj]
+    end
+
     it "returns the value of the proc" do
       Marshal.send(@method, Marshal.dump([1,2]), proc { [3,4] }).should ==  [3,4]
     end
@@ -29,16 +249,15 @@ describe :marshal_load, shared: true do
       a = [1]
       a << a
       ret = []
-      Marshal.send(@method, Marshal.dump(a), proc { |arg| ret << arg; arg })
-      ret.first.should == 1
-      ret[1].should == [1,a]
-      ret[2].should == a
-      ret.size.should == 3
+      Marshal.send(@method, Marshal.dump(a), proc { |arg| ret << arg.inspect; arg })
+      ret[0].should == 1.inspect
+      ret[1].should == a.inspect
+      ret.size.should == 2
     end
 
     it "loads an Array with proc" do
       arr = []
-      s = 'hi'
+      s = +'hi'
       s.instance_variable_set(:@foo, 5)
       st = Struct.new("Brittle", :a).new
       st.instance_variable_set(:@clue, 'none')
@@ -49,13 +268,14 @@ describe :marshal_load, shared: true do
       a.instance_variable_set(:@two, 2)
       obj = [s, 10, s, s, st, a]
       obj.instance_variable_set(:@zoo, 'ant')
-      proc = Proc.new { |o| arr << o; o}
+      proc = Proc.new { |o| arr << o.dup; o}
 
       Marshal.send(@method, "\x04\bI[\vI\"\ahi\a:\x06EF:\t@fooi\ni\x0F@\x06@\x06IS:\x14Struct::Brittle\x06:\x06af\x060\x06:\n@clueI\"\tnone\x06;\x00FI[\b;\b:\x06b:\x06c\x06:\t@twoi\a\x06:\t@zooI\"\bant\x06;\x00F", proc)
 
-      arr.should == ["hi", false, 5, 10, "hi", "hi", 0.0, st, "none", false,
-                     :b, :c, a, 2, ["hi", 10, "hi", "hi", st, [:a, :b, :c]], "ant", false]
-
+      arr.should == [
+        false, 5, "hi", 10, "hi", "hi", 0.0, false, "none", st,
+        :b, :c, 2, a, false, "ant", ["hi", 10, "hi", "hi", st, [:a, :b, :c]],
+      ]
       Struct.send(:remove_const, :Brittle)
     end
   end
@@ -77,12 +297,24 @@ describe :marshal_load, shared: true do
       UserPreviouslyDefinedWithInitializedIvar.should_receive(:_load).and_return(UserPreviouslyDefinedWithInitializedIvar.new)
       marshaled_obj = Marshal.send(@method, dump_str)
 
-      marshaled_obj.should be_an_instance_of(UserPreviouslyDefinedWithInitializedIvar)
-      marshaled_obj.field1.should be_nil
-      marshaled_obj.field2.should be_nil
+      marshaled_obj.should.instance_of?(UserPreviouslyDefinedWithInitializedIvar)
+      marshaled_obj.field1.should == nil
+      marshaled_obj.field2.should == nil
     end
 
-    describe "that return an immediate value" do
+    it "loads the String in non US-ASCII and non UTF-8 encoding" do
+      source_object = UserDefinedString.new("a".encode("windows-1251"))
+      object = Marshal.send(@method, Marshal.dump(source_object))
+      object.string.should == "a".encode("windows-1251")
+    end
+
+    it "loads the String in multibyte encoding" do
+      source_object = UserDefinedString.new("a".encode("utf-32le"))
+      object = Marshal.send(@method, Marshal.dump(source_object))
+      object.string.should == "a".encode("utf-32le")
+    end
+
+    describe "that returns an immediate value" do
       it "loads an array containing an instance of the object, followed by multiple instances of another object" do
         str = "string"
 
@@ -122,26 +354,35 @@ describe :marshal_load, shared: true do
 
   it "loads an array containing objects having _dump method, and with proc" do
     arr = []
-    myproc = Proc.new { |o| arr << o; o }
+    myproc = Proc.new { |o| arr << o.dup; o }
     o1 = UserDefined.new;
     o2 = UserDefinedWithIvar.new
     obj = [o1, o2, o1, o2]
 
     Marshal.send(@method, "\x04\b[\tu:\x10UserDefined\x18\x04\b[\aI\"\nstuff\x06:\x06EF@\x06u:\x18UserDefinedWithIvar>\x04\b[\bI\"\nstuff\a:\x06EF:\t@foo:\x18UserDefinedWithIvarI\"\tmore\x06;\x00F@\a@\x06@\a", myproc)
 
-    arr.should == [o1, o2, o1, o2, obj]
+    arr[0].should == o1
+    arr[1].should == o2
+    arr[2].should == obj
+    arr.size.should == 3
   end
 
   it "loads an array containing objects having marshal_dump method, and with proc" do
     arr = []
-    proc = Proc.new { |o| arr << o; o }
+    proc = Proc.new { |o| arr << o.dup; o }
     o1 = UserMarshal.new
     o2 = UserMarshalWithIvar.new
-    obj = [o1, o2, o1, o2]
 
     Marshal.send(@method, "\004\b[\tU:\020UserMarshal\"\nstuffU:\030UserMarshalWithIvar[\006\"\fmy data@\006@\b", proc)
 
-    arr.should == ['stuff', o1, 'my data', ['my data'], o2, o1, o2, obj]
+    arr[0].should == 'stuff'
+    arr[1].should == o1
+    arr[2].should == 'my data'
+    arr[3].should == ['my data']
+    arr[4].should == o2
+    arr[5].should == [o1, o2, o1, o2]
+
+    arr.size.should == 6
   end
 
   it "assigns classes to nested subclasses of Array correctly" do
@@ -158,111 +399,30 @@ describe :marshal_load, shared: true do
   end
 
   it "raises a TypeError with bad Marshal version" do
-    marshal_data = '\xff\xff'
+    marshal_data = +'\xff\xff'
     marshal_data[0] = (Marshal::MAJOR_VERSION).chr
     marshal_data[1] = (Marshal::MINOR_VERSION + 1).chr
 
-    -> { Marshal.send(@method, marshal_data) }.should raise_error(TypeError)
+    -> { Marshal.send(@method, marshal_data) }.should.raise(TypeError)
 
-    marshal_data = '\xff\xff'
+    marshal_data = +'\xff\xff'
     marshal_data[0] = (Marshal::MAJOR_VERSION - 1).chr
     marshal_data[1] = (Marshal::MINOR_VERSION).chr
 
-    -> { Marshal.send(@method, marshal_data) }.should raise_error(TypeError)
+    -> { Marshal.send(@method, marshal_data) }.should.raise(TypeError)
   end
 
   it "raises EOFError on loading an empty file" do
     temp_file = tmp("marshal.rubyspec.tmp.#{Process.pid}")
     file = File.new(temp_file, "w+")
     begin
-      -> { Marshal.send(@method, file) }.should raise_error(EOFError)
+      -> { Marshal.send(@method, file) }.should.raise(EOFError)
     ensure
       file.close
       rm_r temp_file
     end
   end
 
-  it "returns an untainted object if source is untainted" do
-    x = Object.new
-    y = Marshal.send(@method, Marshal.dump(x))
-    y.tainted?.should be_false
-  end
-
-  describe "when source is tainted" do
-    it "returns a tainted object" do
-      x = Object.new
-      x.taint
-      s = Marshal.dump(x)
-      y = Marshal.send(@method, s)
-      y.tainted?.should be_true
-
-      # note that round-trip via Marshal does not preserve
-      # the taintedness at each level of the nested structure
-      y = Marshal.send(@method, Marshal.dump([[x]]))
-      y.tainted?.should be_true
-      y.first.tainted?.should be_true
-      y.first.first.tainted?.should be_true
-    end
-
-    it "does not taint Symbols" do
-      x = [:x]
-      y = Marshal.send(@method, Marshal.dump(x).taint)
-      y.tainted?.should be_true
-      y.first.tainted?.should be_false
-    end
-
-    it "does not taint Fixnums" do
-      x = [1]
-      y = Marshal.send(@method, Marshal.dump(x).taint)
-      y.tainted?.should be_true
-      y.first.tainted?.should be_false
-    end
-
-    it "does not taint Bignums" do
-      x = [bignum_value]
-      y = Marshal.send(@method, Marshal.dump(x).taint)
-      y.tainted?.should be_true
-      y.first.tainted?.should be_false
-    end
-
-    it "does not taint Floats" do
-      x = [1.2]
-      y = Marshal.send(@method, Marshal.dump(x).taint)
-      y.tainted?.should be_true
-      y.first.tainted?.should be_false
-    end
-  end
-
-  it "preserves taintedness of nested structure" do
-    x = Object.new
-    a = [[x]]
-    x.taint
-    y = Marshal.send(@method, Marshal.dump(a))
-    y.tainted?.should be_true
-    y.first.tainted?.should be_true
-    y.first.first.tainted?.should be_true
-  end
-
-  it "returns a trusted object if source is trusted" do
-    x = Object.new
-    y = Marshal.send(@method, Marshal.dump(x))
-    y.untrusted?.should be_false
-  end
-
-  it "returns an untrusted object if source is untrusted" do
-    x = Object.new
-    x.untrust
-    y = Marshal.send(@method, Marshal.dump(x))
-    y.untrusted?.should be_true
-
-    # note that round-trip via Marshal does not preserve
-    # the untrustedness at each level of the nested structure
-    y = Marshal.send(@method, Marshal.dump([[x]]))
-    y.untrusted?.should be_true
-    y.first.untrusted?.should be_true
-    y.first.first.untrusted?.should be_true
-  end
-
   # Note: Ruby 1.9 should be compatible with older marshal format
   MarshalSpec::DATA.each do |description, (object, marshal, attributes)|
     it "loads a #{description}" do
@@ -296,19 +456,20 @@ describe :marshal_load, shared: true do
     end
 
     it "loads an array having ivar" do
-      s = 'well'
+      s = +'well'
       s.instance_variable_set(:@foo, 10)
       obj = ['5', s, 'hi'].extend(Meths, MethsMore)
       obj.instance_variable_set(:@mix, s)
       new_obj = Marshal.send(@method, "\004\bI[\b\"\0065I\"\twell\006:\t@fooi\017\"\ahi\006:\t@mix@\a")
       new_obj.should == obj
-      new_obj.instance_variable_get(:@mix).should equal new_obj[1]
+      new_obj.instance_variable_get(:@mix).should.equal? new_obj[1]
       new_obj[1].instance_variable_get(:@foo).should == 10
     end
 
     it "loads an extended Array object containing a user-marshaled object" do
       obj = [UserMarshal.new, UserMarshal.new].extend(Meths)
-      new_obj = Marshal.send(@method, "\x04\be:\nMeths[\ao:\x10UserMarshal\x06:\n@dataI\"\nstuff\x06:\x06ETo;\x06\x06;\aI\"\nstuff\x06;\bT")
+      dump = "\x04\be:\nMeths[\ao:\x10UserMarshal\x06:\n@dataI\"\nstuff\x06:\x06ETo;\x06\x06;\aI\"\nstuff\x06;\bT"
+      new_obj = Marshal.send(@method, dump)
 
       new_obj.should == obj
       obj_ancestors = class << obj; ancestors[1..-1]; end
@@ -341,7 +502,7 @@ describe :marshal_load, shared: true do
     end
 
     it "preserves hash ivars when hash contains a string having ivar" do
-      s = 'string'
+      s = +'string'
       s.instance_variable_set :@string_ivar, 'string ivar'
       h = { key: s }
       h.instance_variable_set :@hash_ivar, 'hash ivar'
@@ -350,6 +511,36 @@ describe :marshal_load, shared: true do
       unmarshalled.instance_variable_get(:@hash_ivar).should == 'hash ivar'
       unmarshalled[:key].instance_variable_get(:@string_ivar).should == 'string ivar'
     end
+
+    it "preserves compare_by_identity behaviour" do
+      h = { a: 1 }
+      h.compare_by_identity
+      unmarshalled = Marshal.send(@method, Marshal.dump(h))
+      unmarshalled.should.compare_by_identity?
+
+      h = { a: 1 }
+      unmarshalled = Marshal.send(@method, Marshal.dump(h))
+      unmarshalled.should_not.compare_by_identity?
+    end
+
+    it "preserves compare_by_identity behaviour for a Hash subclass" do
+      h = UserHash.new({ a: 1 })
+      h.compare_by_identity
+      unmarshalled = Marshal.send(@method, Marshal.dump(h))
+      unmarshalled.should.compare_by_identity?
+
+      h = UserHash.new({ a: 1 })
+      unmarshalled = Marshal.send(@method, Marshal.dump(h))
+      unmarshalled.should_not.compare_by_identity?
+    end
+
+    it "allocates an instance of the proper class when Hash subclass with compare_by_identity behaviour" do
+      h = UserHash.new({ a: 1 })
+      h.compare_by_identity
+
+      unmarshalled = Marshal.send(@method, Marshal.dump(h))
+      unmarshalled.should.kind_of?(UserHash)
+    end
   end
 
   describe "for a Symbol" do
@@ -393,23 +584,56 @@ describe :marshal_load, shared: true do
     end
 
     it "loads a binary encoded Symbol" do
-      s = "\u2192".force_encoding("binary").to_sym
+      s = "\u2192".dup.force_encoding("binary").to_sym
       sym = Marshal.send(@method, "\x04\b:\b\xE2\x86\x92")
       sym.should == s
       sym.encoding.should == Encoding::BINARY
     end
+
+    it "loads multiple Symbols sharing the same encoding" do
+      # Note that the encoding is a link for the second Symbol
+      symbol1 = "I:\t\xE2\x82\xACa\x06:\x06ET"
+      symbol2 = "I:\t\xE2\x82\xACb\x06;\x06T"
+      dump = "\x04\b[\a#{symbol1}#{symbol2}"
+      value = Marshal.send(@method, dump)
+      value.map(&:encoding).should == [Encoding::UTF_8, Encoding::UTF_8]
+      expected = [
+        "€a".dup.force_encoding(Encoding::UTF_8).to_sym,
+        "€b".dup.force_encoding(Encoding::UTF_8).to_sym
+      ]
+      value.should == expected
+
+      value = Marshal.send(@method, "\x04\b[\b#{symbol1}#{symbol2};\x00")
+      value.map(&:encoding).should == [Encoding::UTF_8, Encoding::UTF_8, Encoding::UTF_8]
+      value.should == [*expected, expected[0]]
+    end
+
+    it "raises ArgumentError when end of byte sequence reached before symbol characters end" do
+      Marshal.dump(:hello).should == "\x04\b:\nhello"
+
+      -> {
+        Marshal.send(@method, "\x04\b:\nhel")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
   end
 
   describe "for a String" do
     it "loads a string having ivar with ref to self" do
-      obj = 'hi'
+      obj = +'hi'
       obj.instance_variable_set(:@self, obj)
       Marshal.send(@method, "\004\bI\"\ahi\006:\n@self@\000").should == obj
     end
 
     it "loads a string through StringIO stream" do
-        obj = "This is a string which should be unmarshalled through StringIO stream!"
-        Marshal.send(@method, StringIO.new(Marshal.dump(obj))).should == obj
+      require 'stringio'
+      obj = "This is a string which should be unmarshalled through StringIO stream!"
+      Marshal.send(@method, StringIO.new(Marshal.dump(obj))).should == obj
+    end
+
+    it "sets binmode if it is loading through StringIO stream" do
+      io = StringIO.new("\004\b:\vsymbol")
+      def io.binmode; raise "binmode"; end
+      -> { Marshal.load(io) }.should.raise(RuntimeError, "binmode")
     end
 
     it "loads a string with an ivar" do
@@ -419,59 +643,70 @@ describe :marshal_load, shared: true do
 
     it "loads a String subclass with custom constructor" do
       str = Marshal.send(@method, "\x04\bC: UserCustomConstructorString\"\x00")
-      str.should be_an_instance_of(UserCustomConstructorString)
+      str.should.instance_of?(UserCustomConstructorString)
     end
 
     it "loads a US-ASCII String" do
-      str = "abc".force_encoding("us-ascii")
+      str = "abc".dup.force_encoding("us-ascii")
       data = "\x04\bI\"\babc\x06:\x06EF"
       result = Marshal.send(@method, data)
       result.should == str
-      result.encoding.should equal(Encoding::US_ASCII)
+      result.encoding.should.equal?(Encoding::US_ASCII)
     end
 
     it "loads a UTF-8 String" do
-      str = "\x6d\xc3\xb6\x68\x72\x65".force_encoding("utf-8")
+      str = "\x6d\xc3\xb6\x68\x72\x65".dup.force_encoding("utf-8")
       data = "\x04\bI\"\vm\xC3\xB6hre\x06:\x06ET"
       result = Marshal.send(@method, data)
       result.should == str
-      result.encoding.should equal(Encoding::UTF_8)
+      result.encoding.should.equal?(Encoding::UTF_8)
     end
 
     it "loads a String in another encoding" do
-      str = "\x6d\x00\xf6\x00\x68\x00\x72\x00\x65\x00".force_encoding("utf-16le")
+      str = "\x6d\x00\xf6\x00\x68\x00\x72\x00\x65\x00".dup.force_encoding("utf-16le")
       data = "\x04\bI\"\x0Fm\x00\xF6\x00h\x00r\x00e\x00\x06:\rencoding\"\rUTF-16LE"
       result = Marshal.send(@method, data)
       result.should == str
-      result.encoding.should equal(Encoding::UTF_16LE)
+      result.encoding.should.equal?(Encoding::UTF_16LE)
     end
 
     it "loads a String as BINARY if no encoding is specified at the end" do
-      str = "\xC3\xB8".force_encoding("BINARY")
-      data = "\x04\b\"\a\xC3\xB8".force_encoding("UTF-8")
+      str = "\xC3\xB8".dup.force_encoding("BINARY")
+      data = "\x04\b\"\a\xC3\xB8".dup.force_encoding("UTF-8")
       result = Marshal.send(@method, data)
       result.encoding.should == Encoding::BINARY
       result.should == str
     end
+
+    it "raises ArgumentError when end of byte sequence reached before string characters end" do
+      Marshal.dump("hello").should == "\x04\b\"\nhello"
+
+      -> {
+        Marshal.send(@method, "\x04\b\"\nhel")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
   end
 
   describe "for a Struct" do
     it "loads a extended_struct having fields with same objects" do
       s = 'hi'
-      obj = Struct.new("Ure2", :a, :b).new.extend(Meths)
+      obj = Struct.new("Extended", :a, :b).new.extend(Meths)
+      dump = "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+      Marshal.send(@method, dump).should == obj
+
       obj.a = [:a, s]
       obj.b = [:Meths, s]
-
-      Marshal.send(@method,
-        "\004\be:\nMethsS:\021Struct::Ure2\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
-        ).should == obj
-      Struct.send(:remove_const, :Ure2)
+      dump = "\004\be:\nMethsS:\025Struct::Extended\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
+      Marshal.send(@method, dump).should == obj
+      Struct.send(:remove_const, :Extended)
     end
 
     it "loads a struct having ivar" do
       obj = Struct.new("Thick").new
       obj.instance_variable_set(:@foo, 5)
-      Marshal.send(@method, "\004\bIS:\022Struct::Thick\000\006:\t@fooi\n").should == obj
+      reloaded = Marshal.send(@method, "\004\bIS:\022Struct::Thick\000\006:\t@fooi\n")
+      reloaded.should == obj
+      reloaded.instance_variable_get(:@foo).should == 5
       Struct.send(:remove_const, :Thick)
     end
 
@@ -498,6 +733,32 @@ describe :marshal_load, shared: true do
     end
   end
 
+  describe "for a Data" do
+    it "loads a Data" do
+      obj = MarshalSpec::DataSpec::Measure.new(100, 'km')
+      dumped = "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+      Marshal.dump(obj).should == dumped
+
+      Marshal.send(@method, dumped).should == obj
+    end
+
+    it "loads an extended Data" do
+      obj = MarshalSpec::DataSpec::MeasureExtended.new(100, "km")
+      dumped = "\x04\bS:+MarshalSpec::DataSpec::MeasureExtended\a:\vamountii:\tunit\"\akm"
+      Marshal.dump(obj).should == dumped
+
+      Marshal.send(@method, dumped).should == obj
+    end
+
+    it "returns a frozen object" do
+      obj = MarshalSpec::DataSpec::Measure.new(100, 'km')
+      dumped = "\x04\bS:#MarshalSpec::DataSpec::Measure\a:\vamountii:\tunit\"\akm"
+      Marshal.dump(obj).should == dumped
+
+      Marshal.send(@method, dumped).should.frozen?
+    end
+  end
+
   describe "for an Exception" do
     it "loads a marshalled exception with no message" do
       obj = Exception.new
@@ -529,11 +790,24 @@ describe :marshal_load, shared: true do
       loaded.message.should == obj.message
       loaded.backtrace.should == obj.backtrace
     end
+
+    it "loads an marshalled exception with ivars" do
+      s = 'hi'
+      arr = [:so, :so, s, s]
+      obj = Exception.new("foo")
+      obj.instance_variable_set :@arr, arr
+
+      loaded = Marshal.send(@method, "\x04\bo:\x0EException\b:\tmesg\"\bfoo:\abt0:\t@arr[\t:\aso;\t\"\ahi@\b")
+      new_arr = loaded.instance_variable_get :@arr
+
+      loaded.message.should == obj.message
+      new_arr.should == arr
+    end
   end
 
   describe "for an Object" do
     it "loads an object" do
-      Marshal.send(@method, "\004\bo:\vObject\000").should be_kind_of(Object)
+      Marshal.send(@method, "\004\bo:\vObject\000").should.is_a?(Object)
     end
 
     it "loads an extended Object" do
@@ -559,7 +833,7 @@ describe :marshal_load, shared: true do
     end
 
     it "loads an Object with a non-US-ASCII instance variable" do
-      ivar = "@é".force_encoding(Encoding::UTF_8).to_sym
+      ivar = "@é".dup.force_encoding(Encoding::UTF_8).to_sym
       obj = Marshal.send(@method, "\x04\bo:\vObject\x06I:\b@\xC3\xA9\x06:\x06ETi\x06")
       obj.instance_variables.should == [ivar]
       obj.instance_variables[0].encoding.should == Encoding::UTF_8
@@ -569,7 +843,27 @@ describe :marshal_load, shared: true do
     it "raises ArgumentError if the object from an 'o' stream is not dumpable as 'o' type user class" do
       -> do
         Marshal.send(@method, "\x04\bo:\tFile\001\001:\001\005@path\"\x10/etc/passwd")
-      end.should raise_error(ArgumentError)
+      end.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError when end of byte sequence reached before class name end" do
+      Marshal.dump(Object.new).should == "\x04\bo:\vObject\x00"
+
+      -> {
+        Marshal.send(@method, "\x04\bo:\vObj")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
+  end
+
+  describe "for an object responding to #marshal_dump and #marshal_load" do
+    it "loads a user-marshaled object" do
+      obj = UserMarshal.new
+      obj.data = :data
+      value = [obj, :data]
+      dump = Marshal.dump(value)
+      dump.should == "\x04\b[\aU:\x10UserMarshal:\tdata;\x06"
+      reloaded = Marshal.load(dump)
+      reloaded.should == value
     end
   end
 
@@ -585,7 +879,7 @@ describe :marshal_load, shared: true do
     end
 
     it "loads a UserObject" do
-      Marshal.send(@method, "\004\bo:\017UserObject\000").should be_kind_of(UserObject)
+      Marshal.send(@method, "\004\bo:\017UserObject\000").should.is_a?(UserObject)
     end
 
     describe "that extends a core type other than Object or BasicObject" do
@@ -598,26 +892,64 @@ describe :marshal_load, shared: true do
         data = Marshal.dump(MarshalSpec::SwappedClass.new)
 
         MarshalSpec.set_swapped_class(Class.new(Array))
-        -> { Marshal.send(@method, data) }.should raise_error(ArgumentError)
+        -> { Marshal.send(@method, data) }.should.raise(ArgumentError)
 
         MarshalSpec.set_swapped_class(Class.new)
-        -> { Marshal.send(@method, data) }.should raise_error(ArgumentError)
+        -> { Marshal.send(@method, data) }.should.raise(ArgumentError)
       end
     end
   end
 
   describe "for a Regexp" do
-    it "loads an extended Regexp" do
-      obj = /[a-z]/.extend(Meths, MethsMore)
-      new_obj = Marshal.send(@method, "\004\be:\nMethse:\016MethsMore/\n[a-z]\000")
+    ruby_version_is "4.1" do
+      it "raises FrozenError for an extended Regexp" do
+        -> {
+          Marshal.send(@method, "\004\be:\nMethse:\016MethsMore/\n[a-z]\000")
+        }.should.raise(FrozenError)
+      end
+
+      it "raises FrozenError when regexp has instance variables" do
+        -> {
+          Marshal.send(@method, "\x04\bI/\nhello\x00\a:\x06EF:\x11@regexp_ivar[\x06i/")
+        }.should.raise(FrozenError)
+      end
+    end
+
+    ruby_version_is ""..."4.1" do
+      it "loads an extended Regexp" do
+        obj = /[a-z]/.dup.extend(Meths, MethsMore)
+        new_obj = Marshal.send(@method, "\004\be:\nMethse:\016MethsMore/\n[a-z]\000")
+
+        new_obj.should == obj
+        new_obj_metaclass_ancestors = class << new_obj; ancestors; end
+        new_obj_metaclass_ancestors[@num_self_class, 3].should ==
+          [Meths, MethsMore, Regexp]
+      end
+
+      it "restore the regexp instance variables" do
+        obj = Regexp.new("hello")
+        obj.instance_variable_set(:@regexp_ivar, [42])
+
+        new_obj = Marshal.send(@method, "\x04\bI/\nhello\x00\a:\x06EF:\x11@regexp_ivar[\x06i/")
+        new_obj.instance_variables.should == [:@regexp_ivar]
+        new_obj.instance_variable_get(:@regexp_ivar).should == [42]
+      end
+    end
+
+    it "loads a Regexp subclass instance variables" do
+      obj = UserRegexp.new('abc')
+      obj.instance_variable_set(:@noise, 'much')
+
+      new_obj = Marshal.send(@method, Marshal.dump(obj))
 
       new_obj.should == obj
+      new_obj.instance_variable_get(:@noise).should == 'much'
       new_obj_metaclass_ancestors = class << new_obj; ancestors; end
-      new_obj_metaclass_ancestors[@num_self_class, 3].should ==
-        [Meths, MethsMore, Regexp]
+      new_obj_metaclass_ancestors[@num_self_class, 2].should ==
+        [UserRegexp, Regexp]
     end
 
-    it "loads a extended_user_regexp having ivar" do
+    it "loads a Regexp subclass instance variables when it is extended with a module" do
       obj = UserRegexp.new('').extend(Meths)
       obj.instance_variable_set(:@noise, 'much')
 
@@ -629,6 +961,22 @@ describe :marshal_load, shared: true do
       new_obj_metaclass_ancestors[@num_self_class, 3].should ==
         [Meths, UserRegexp, Regexp]
     end
+
+    it "preserves Regexp encoding" do
+      source_object = Regexp.new("a".encode("utf-32le"))
+      regexp = Marshal.send(@method, Marshal.dump(source_object))
+
+      regexp.encoding.should == Encoding::UTF_32LE
+      regexp.source.should == "a".encode("utf-32le")
+    end
+
+    it "raises ArgumentError when end of byte sequence reached before source string end" do
+      Marshal.dump(/hello world/).should == "\x04\bI/\x10hello world\x00\x06:\x06EF"
+
+      -> {
+        Marshal.send(@method, "\x04\bI/\x10hel")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
   end
 
   describe "for a Float" do
@@ -650,9 +998,17 @@ describe :marshal_load, shared: true do
       obj = 1.1867345e+22
       Marshal.send(@method, "\004\bf\0361.1867344999999999e+22\000\344@").should == obj
     end
+
+    it "raises ArgumentError when end of byte sequence reached before float string representation end" do
+      Marshal.dump(1.3).should == "\x04\bf\b1.3"
+
+      -> {
+        Marshal.send(@method, "\004\bf\v1")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
   end
 
-  describe "for a Integer" do
+  describe "for an Integer" do
     it "loads 0" do
       Marshal.send(@method, "\004\bi\000").should == 0
       Marshal.send(@method, "\004\bi\005").should == 0
@@ -702,7 +1058,7 @@ describe :marshal_load, shared: true do
        "\004\bi\004\0",
        "\004\bi\004\0\0",
        "\004\bi\004\0\0\0"].each do |invalid|
-        -> { Marshal.send(@method, invalid) }.should raise_error(ArgumentError)
+        -> { Marshal.send(@method, invalid) }.should.raise(ArgumentError)
       end
     end
 
@@ -715,29 +1071,33 @@ describe :marshal_load, shared: true do
 
   describe "for a Rational" do
     it "loads" do
-      Marshal.send(@method, Marshal.dump(Rational(1, 3))).should == Rational(1, 3)
+      r = Marshal.send(@method, Marshal.dump(Rational(1, 3)))
+      r.should == Rational(1, 3)
+      r.should.frozen?
     end
   end
 
   describe "for a Complex" do
     it "loads" do
-      Marshal.send(@method, Marshal.dump(Complex(4, 3))).should == Complex(4, 3)
+      c = Marshal.send(@method, Marshal.dump(Complex(4, 3)))
+      c.should == Complex(4, 3)
+      c.should.frozen?
     end
   end
 
   describe "for a Bignum" do
-    platform_is wordsize: 64 do
+    platform_is c_long_size: 64 do
       context "that is Bignum on 32-bit platforms but Fixnum on 64-bit" do
         it "dumps a Fixnum" do
           val = Marshal.send(@method, "\004\bl+\ab:wU")
           val.should == 1433877090
-          val.class.should == Fixnum
+          val.class.should == Integer
         end
 
         it "dumps an array containing multiple references to the Bignum as an array of Fixnum" do
           arr = Marshal.send(@method, "\004\b[\al+\a\223BwU@\006")
           arr.should == [1433879187, 1433879187]
-          arr.each { |v| v.class.should == Fixnum }
+          arr.each { |v| v.class.should == Integer }
         end
       end
     end
@@ -759,37 +1119,67 @@ describe :marshal_load, shared: true do
       t = Time.new
 
       t1, t2 = Marshal.send(@method, Marshal.dump([t, t]))
-      t1.should equal t2
+      t1.should.equal? t2
     end
 
-    it "loads the zone" do
+    it "keeps the local zone" do
       with_timezone 'AST', 3 do
         t = Time.local(2012, 1, 1)
         Marshal.send(@method, Marshal.dump(t)).zone.should == t.zone
       end
     end
 
-    it "loads nanoseconds" do
+    it "keeps UTC zone" do
+      t = Time.now.utc
+      t2 = Marshal.send(@method, Marshal.dump(t))
+      t2.should.utc?
+    end
+
+    it "keeps the zone" do
+      t = nil
+
+      with_timezone 'AST', 4 do
+        t = Time.local(2012, 1, 1)
+      end
+
+      with_timezone 'EET', -2 do
+        Marshal.send(@method, Marshal.dump(t)).zone.should == 'AST'
+      end
+    end
+
+    it "keeps utc offset" do
+      t = Time.new(2007,11,1,15,25,0, "+09:00")
+      t2 = Marshal.send(@method, Marshal.dump(t))
+      t2.utc_offset.should == 32400
+    end
+
+    it "keeps nanoseconds" do
       t = Time.now
       Marshal.send(@method, Marshal.dump(t)).nsec.should == t.nsec
     end
+
+    it "does not add any additional instance variable" do
+      t = Time.now
+      t2 = Marshal.send(@method, Marshal.dump(t))
+      t2.instance_variables.should.empty?
+    end
   end
 
   describe "for nil" do
     it "loads" do
-      Marshal.send(@method, "\x04\b0").should be_nil
+      Marshal.send(@method, "\x04\b0").should == nil
     end
   end
 
   describe "for true" do
     it "loads" do
-      Marshal.send(@method, "\x04\bT").should be_true
+      Marshal.send(@method, "\x04\bT").should == true
     end
   end
 
   describe "for false" do
     it "loads" do
-      Marshal.send(@method, "\x04\bF").should be_false
+      Marshal.send(@method, "\x04\bF").should == false
     end
   end
 
@@ -799,11 +1189,19 @@ describe :marshal_load, shared: true do
     end
 
     it "raises ArgumentError if given the name of a non-Module" do
-      -> { Marshal.send(@method, "\x04\bc\vKernel") }.should raise_error(ArgumentError)
+      -> { Marshal.send(@method, "\x04\bc\vKernel") }.should.raise(ArgumentError)
     end
 
     it "raises ArgumentError if given a nonexistent class" do
-      -> { Marshal.send(@method, "\x04\bc\vStrung") }.should raise_error(ArgumentError)
+      -> { Marshal.send(@method, "\x04\bc\vStrung") }.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError when end of byte sequence reached before class name end" do
+      Marshal.dump(String).should == "\x04\bc\vString"
+
+      -> {
+        Marshal.send(@method, "\x04\bc\vStr")
+      }.should.raise(ArgumentError, "marshal data too short")
     end
   end
 
@@ -813,12 +1211,20 @@ describe :marshal_load, shared: true do
     end
 
     it "raises ArgumentError if given the name of a non-Class" do
-      -> { Marshal.send(@method, "\x04\bm\vString") }.should raise_error(ArgumentError)
+      -> { Marshal.send(@method, "\x04\bm\vString") }.should.raise(ArgumentError)
     end
 
     it "loads an old module" do
       Marshal.send(@method, "\x04\bM\vKernel").should == Kernel
     end
+
+    it "raises ArgumentError when end of byte sequence reached before module name end" do
+      Marshal.dump(Kernel).should == "\x04\bm\vKernel"
+
+      -> {
+        Marshal.send(@method, "\x04\bm\vKer")
+      }.should.raise(ArgumentError, "marshal data too short")
+    end
   end
 
   describe "for a wrapped C pointer" do
@@ -852,13 +1258,13 @@ describe :marshal_load, shared: true do
 
       data = "\x04\bd:\x1AUnloadableDumpableDirI\"\x06.\x06:\x06ET"
 
-      -> { Marshal.send(@method, data) }.should raise_error(TypeError)
+      -> { Marshal.send(@method, data) }.should.raise(TypeError)
     end
 
     it "raises ArgumentError when the local class is a regular object" do
       data = "\004\bd:\020UserDefined\0"
 
-      -> { Marshal.send(@method, data) }.should raise_error(ArgumentError)
+      -> { Marshal.send(@method, data) }.should.raise(ArgumentError)
     end
   end
 
@@ -871,7 +1277,7 @@ describe :marshal_load, shared: true do
 
     it "raises an ArgumentError" do
       message = "undefined class/module NamespaceTest::SameName"
-      -> { Marshal.send(@method, @data) }.should raise_error(ArgumentError, message)
+      -> { Marshal.send(@method, @data) }.should.raise(ArgumentError, message)
     end
   end
 
@@ -880,6 +1286,6 @@ describe :marshal_load, shared: true do
     @data = Marshal.dump(NamespaceTest::KaBoom.new)
     NamespaceTest.send(:remove_const, :KaBoom)
 
-    -> { Marshal.send(@method, @data) }.should raise_error(ArgumentError, /NamespaceTest::KaBoom/)
+    -> { Marshal.send(@method, @data) }.should.raise(ArgumentError, /NamespaceTest::KaBoom/)
   end
 end
diff --git a/spec/ruby/core/matchdata/allocate_spec.rb b/spec/ruby/core/matchdata/allocate_spec.rb
new file mode 100644
index 0000000000..f41e2d5481
--- /dev/null
+++ b/spec/ruby/core/matchdata/allocate_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+
+describe "MatchData.allocate" do
+  it "is undefined" do
+    # https://bugs.ruby-lang.org/issues/16294
+    -> { MatchData.allocate }.should.raise(NoMethodError)
+  end
+end
diff --git a/spec/ruby/core/matchdata/begin_spec.rb b/spec/ruby/core/matchdata/begin_spec.rb
index 85c454da56..b4be077ae4 100644
--- a/spec/ruby/core/matchdata/begin_spec.rb
+++ b/spec/ruby/core/matchdata/begin_spec.rb
@@ -12,7 +12,7 @@ describe "MatchData#begin" do
 
     it "returns nil when the nth match isn't found" do
       match_data = /something is( not)? (right)/.match("something is right")
-      match_data.begin(1).should be_nil
+      match_data.begin(1).should == nil
     end
 
     it "returns the character offset for multi-byte strings" do
@@ -36,6 +36,18 @@ describe "MatchData#begin" do
       match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
       match_data.begin(obj).should == 2
     end
+
+    it "raises IndexError if index is out of bounds" do
+      match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+      -> {
+        match_data.begin(-1)
+      }.should.raise(IndexError, "index -1 out of matches")
+
+      -> {
+        match_data.begin(3)
+      }.should.raise(IndexError, "index 3 out of matches")
+    end
   end
 
   context "when passed a String argument" do
@@ -68,6 +80,14 @@ describe "MatchData#begin" do
       match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
       match_data.begin("æ").should == 1
     end
+
+    it "raises IndexError if there is no group with the provided name" do
+      match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+      -> {
+        match_data.begin("y")
+      }.should.raise(IndexError, "undefined group name reference: y")
+    end
   end
 
   context "when passed a Symbol argument" do
@@ -100,5 +120,13 @@ describe "MatchData#begin" do
       match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
       match_data.begin(:æ).should == 1
     end
+
+    it "raises IndexError if there is no group with the provided name" do
+      match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+      -> {
+        match_data.begin(:y)
+      }.should.raise(IndexError, "undefined group name reference: y")
+    end
   end
 end
diff --git a/spec/ruby/core/matchdata/bytebegin_spec.rb b/spec/ruby/core/matchdata/bytebegin_spec.rb
new file mode 100644
index 0000000000..fa44ec3b41
--- /dev/null
+++ b/spec/ruby/core/matchdata/bytebegin_spec.rb
@@ -0,0 +1,132 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "3.4" do
+  describe "MatchData#bytebegin" do
+    context "when passed an integer argument" do
+      it "returns the byte-based offset of the start of the nth element" do
+        match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin(0).should == 1
+        match_data.bytebegin(2).should == 2
+      end
+
+      it "returns nil when the nth match isn't found" do
+        match_data = /something is( not)? (right)/.match("something is right")
+        match_data.bytebegin(1).should == nil
+      end
+
+      it "returns the byte-based offset for multi-byte strings" do
+        match_data = /(.)(.)(\d+)(\d)/.match("TñX1138.")
+        match_data.bytebegin(0).should == 1
+        match_data.bytebegin(2).should == 3
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi-byte strings with unicode regexp" do
+          match_data = /(.)(.)(\d+)(\d)/u.match("TñX1138.")
+          match_data.bytebegin(0).should == 1
+          match_data.bytebegin(2).should == 3
+        end
+      end
+
+      it "tries to convert the passed argument to an Integer using #to_int" do
+        obj = mock('to_int')
+        obj.should_receive(:to_int).and_return(2)
+
+        match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin(obj).should == 2
+      end
+
+      it "raises IndexError if index is out of bounds" do
+        match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+        -> {
+          match_data.bytebegin(-1)
+        }.should.raise(IndexError, "index -1 out of matches")
+
+        -> {
+          match_data.bytebegin(3)
+        }.should.raise(IndexError, "index 3 out of matches")
+      end
+    end
+
+    context "when passed a String argument" do
+      it "return the byte-based offset of the start of the named capture" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin("a").should == 1
+        match_data.bytebegin("b").should == 3
+      end
+
+      it "returns the byte-based offset for multi byte strings" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("TñX1138.")
+        match_data.bytebegin("a").should == 1
+        match_data.bytebegin("b").should == 4
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi byte strings with unicode regexp" do
+          match_data = /(?<a>.)(.)(?<b>\d+)(\d)/u.match("TñX1138.")
+          match_data.bytebegin("a").should == 1
+          match_data.bytebegin("b").should == 4
+        end
+      end
+
+      it "returns the byte-based offset for the farthest match when multiple named captures use the same name" do
+        match_data = /(?<a>.)(.)(?<a>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin("a").should == 3
+      end
+
+      it "returns the byte-based offset for multi-byte names" do
+        match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin("æ").should == 1
+      end
+
+      it "raises IndexError if there is no group with the provided name" do
+        match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+        -> {
+          match_data.bytebegin("y")
+        }.should.raise(IndexError, "undefined group name reference: y")
+      end
+    end
+
+    context "when passed a Symbol argument" do
+      it "return the byte-based offset of the start of the named capture" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin(:a).should == 1
+        match_data.bytebegin(:b).should == 3
+      end
+
+      it "returns the byte-based offset for multi byte strings" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("TñX1138.")
+        match_data.bytebegin(:a).should == 1
+        match_data.bytebegin(:b).should == 4
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi byte strings with unicode regexp" do
+          match_data = /(?<a>.)(.)(?<b>\d+)(\d)/u.match("TñX1138.")
+          match_data.bytebegin(:a).should == 1
+          match_data.bytebegin(:b).should == 4
+        end
+      end
+
+      it "returns the byte-based offset for the farthest match when multiple named captures use the same name" do
+        match_data = /(?<a>.)(.)(?<a>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin(:a).should == 3
+      end
+
+      it "returns the byte-based offset for multi-byte names" do
+        match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.bytebegin(:æ).should == 1
+      end
+
+      it "raises IndexError if there is no group with the provided name" do
+        match_data = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+        -> {
+          match_data.bytebegin(:y)
+        }.should.raise(IndexError, "undefined group name reference: y")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/matchdata/byteend_spec.rb b/spec/ruby/core/matchdata/byteend_spec.rb
new file mode 100644
index 0000000000..e77cbf8b0d
--- /dev/null
+++ b/spec/ruby/core/matchdata/byteend_spec.rb
@@ -0,0 +1,104 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "3.4" do
+  describe "MatchData#byteend" do
+    context "when passed an integer argument" do
+      it "returns the byte-based offset of the end of the nth element" do
+        match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
+        match_data.byteend(0).should == 7
+        match_data.byteend(2).should == 3
+      end
+
+      it "returns nil when the nth match isn't found" do
+        match_data = /something is( not)? (right)/.match("something is right")
+        match_data.byteend(1).should == nil
+      end
+
+      it "returns the byte-based offset for multi-byte strings" do
+        match_data = /(.)(.)(\d+)(\d)/.match("TñX1138.")
+        match_data.byteend(0).should == 8
+        match_data.byteend(2).should == 4
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi-byte strings with unicode regexp" do
+          match_data = /(.)(.)(\d+)(\d)/u.match("TñX1138.")
+          match_data.byteend(0).should == 8
+          match_data.byteend(2).should == 4
+        end
+      end
+
+      it "tries to convert the passed argument to an Integer using #to_int" do
+        obj = mock('to_int')
+        obj.should_receive(:to_int).and_return(2)
+
+        match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
+        match_data.byteend(obj).should == 3
+      end
+    end
+
+    context "when passed a String argument" do
+      it "return the byte-based offset of the start of the named capture" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.byteend("a").should == 2
+        match_data.byteend("b").should == 6
+      end
+
+      it "returns the byte-based offset for multi byte strings" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("TñX1138.")
+        match_data.byteend("a").should == 3
+        match_data.byteend("b").should == 7
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi byte strings with unicode regexp" do
+          match_data = /(?<a>.)(.)(?<b>\d+)(\d)/u.match("TñX1138.")
+          match_data.byteend("a").should == 3
+          match_data.byteend("b").should == 7
+        end
+      end
+
+      it "returns the byte-based offset for the farthest match when multiple named captures use the same name" do
+        match_data = /(?<a>.)(.)(?<a>\d+)(\d)/.match("THX1138.")
+        match_data.byteend("a").should == 6
+      end
+
+      it "returns the byte-based offset for multi-byte names" do
+        match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.byteend("æ").should == 2
+      end
+    end
+
+    context "when passed a Symbol argument" do
+      it "return the byte-based offset of the start of the named capture" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.byteend(:a).should == 2
+        match_data.byteend(:b).should == 6
+      end
+
+      it "returns the byte-based offset for multi byte strings" do
+        match_data = /(?<a>.)(.)(?<b>\d+)(\d)/.match("TñX1138.")
+        match_data.byteend(:a).should == 3
+        match_data.byteend(:b).should == 7
+      end
+
+      not_supported_on :opal do
+        it "returns the byte-based offset for multi byte strings with unicode regexp" do
+          match_data = /(?<a>.)(.)(?<b>\d+)(\d)/u.match("TñX1138.")
+          match_data.byteend(:a).should == 3
+          match_data.byteend(:b).should == 7
+        end
+      end
+
+      it "returns the byte-based offset for the farthest match when multiple named captures use the same name" do
+        match_data = /(?<a>.)(.)(?<a>\d+)(\d)/.match("THX1138.")
+        match_data.byteend(:a).should == 6
+      end
+
+      it "returns the byte-based offset for multi-byte names" do
+        match_data = /(?<æ>.)(.)(?<b>\d+)(\d)/.match("THX1138.")
+        match_data.byteend(:æ).should == 2
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/matchdata/byteoffset_spec.rb b/spec/ruby/core/matchdata/byteoffset_spec.rb
new file mode 100644
index 0000000000..062e84027c
--- /dev/null
+++ b/spec/ruby/core/matchdata/byteoffset_spec.rb
@@ -0,0 +1,93 @@
+require_relative '../../spec_helper'
+
+describe "MatchData#byteoffset" do
+  it "returns beginning and ending byte-based offset of whole matched substring for 0 element" do
+    m = /(.)(.)(\d+)(\d)/.match("THX1138.")
+    m.byteoffset(0).should == [1, 7]
+  end
+
+  it "returns beginning and ending byte-based offset of n-th match, all the subsequent elements are capturing groups" do
+    m = /(.)(.)(\d+)(\d)/.match("THX1138.")
+
+    m.byteoffset(2).should == [2, 3]
+    m.byteoffset(3).should == [3, 6]
+    m.byteoffset(4).should == [6, 7]
+  end
+
+  it "accepts String as a reference to a named capture" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.byteoffset("f").should == [0, 3]
+    m.byteoffset("b").should == [3, 6]
+  end
+
+  it "accepts Symbol as a reference to a named capture" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.byteoffset(:f).should == [0, 3]
+    m.byteoffset(:b).should == [3, 6]
+  end
+
+  it "returns [nil, nil] if a capturing group is optional and doesn't match" do
+    m = /(?<x>q..)?/.match("foobarbaz")
+
+    m.byteoffset("x").should == [nil, nil]
+    m.byteoffset(1).should == [nil, nil]
+  end
+
+  it "returns correct beginning and ending byte-based offset for multi-byte strings" do
+    m = /\A\u3042(.)(.)?(.)\z/.match("\u3042\u3043\u3044")
+
+    m.byteoffset(1).should == [3, 6]
+    m.byteoffset(3).should == [6, 9]
+  end
+
+  it "returns [nil, nil] if a capturing group is optional and doesn't match for multi-byte string" do
+    m = /\A\u3042(.)(.)?(.)\z/.match("\u3042\u3043\u3044")
+
+    m.byteoffset(2).should == [nil, nil]
+  end
+
+  it "converts argument into integer if is not String nor Symbol" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    obj = Object.new
+    def obj.to_int; 2; end
+
+    m.byteoffset(1r).should == [0, 3]
+    m.byteoffset(1.1).should == [0, 3]
+    m.byteoffset(obj).should == [3, 6]
+  end
+
+  it "raises IndexError if there is no group with the provided name" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.byteoffset("y")
+    }.should.raise(IndexError, "undefined group name reference: y")
+
+    -> {
+      m.byteoffset(:y)
+    }.should.raise(IndexError, "undefined group name reference: y")
+  end
+
+  it "raises IndexError if index is out of bounds" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.byteoffset(-1)
+    }.should.raise(IndexError, "index -1 out of matches")
+
+    -> {
+      m.byteoffset(3)
+    }.should.raise(IndexError, "index 3 out of matches")
+  end
+
+  it "raises TypeError if can't convert argument into Integer" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.byteoffset([])
+    }.should.raise(TypeError, "no implicit conversion of Array into Integer")
+  end
+end
diff --git a/spec/ruby/core/matchdata/captures_spec.rb b/spec/ruby/core/matchdata/captures_spec.rb
index 8c0d2978b7..f829a25481 100644
--- a/spec/ruby/core/matchdata/captures_spec.rb
+++ b/spec/ruby/core/matchdata/captures_spec.rb
@@ -1,7 +1,6 @@
 require_relative '../../spec_helper'
+require_relative 'shared/captures'
 
 describe "MatchData#captures" do
-  it "returns an array of the match captures" do
-    /(.)(.)(\d+)(\d)/.match("THX1138.").captures.should == ["H","X","113","8"]
-  end
+  it_behaves_like :matchdata_captures, :captures
 end
diff --git a/spec/ruby/core/matchdata/deconstruct_keys_spec.rb b/spec/ruby/core/matchdata/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..9126d20394
--- /dev/null
+++ b/spec/ruby/core/matchdata/deconstruct_keys_spec.rb
@@ -0,0 +1,78 @@
+require_relative '../../spec_helper'
+
+describe "MatchData#deconstruct_keys" do
+  it "returns whole hash for nil as an argument" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.deconstruct_keys(nil).should == { f: "foo", b: "bar" }
+  end
+
+  it "returns only specified keys" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.deconstruct_keys([:f]).should == { f: "foo" }
+  end
+
+  it "requires one argument" do
+    m = /l/.match("l")
+
+    -> {
+      m.deconstruct_keys
+    }.should.raise(ArgumentError, "wrong number of arguments (given 0, expected 1)")
+  end
+
+  it "it raises error when argument is neither nil nor array" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> { m.deconstruct_keys(1) }.should.raise(TypeError, "wrong argument type Integer (expected Array)")
+    -> { m.deconstruct_keys("asd") }.should.raise(TypeError, "wrong argument type String (expected Array)")
+    -> { m.deconstruct_keys(:x) }.should.raise(TypeError, "wrong argument type Symbol (expected Array)")
+    -> { m.deconstruct_keys({}) }.should.raise(TypeError, "wrong argument type Hash (expected Array)")
+  end
+
+  it "returns {} when passed []" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.deconstruct_keys([]).should == {}
+  end
+
+  it "does not accept non-Symbol keys" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.deconstruct_keys(['year', :foo])
+    }.should.raise(TypeError, "wrong argument type String (expected Symbol)")
+  end
+
+  it "process keys till the first non-existing one" do
+    m = /(?<f>foo)(?<b>bar)(?<c>baz)/.match("foobarbaz")
+
+    m.deconstruct_keys([:f, :a, :b]).should == { f: "foo" }
+  end
+
+  it "returns {} when there are no named captured groups at all" do
+    m = /foo.+/.match("foobar")
+
+    m.deconstruct_keys(nil).should == {}
+  end
+
+  it "returns {} when passed more keys than named captured groups" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+    m.deconstruct_keys([:f, :b, :c]).should == {}
+  end
+
+  it "includes non-participating captures as nil for nil argument" do
+    m = "hello".match(/(?<a>hello)(?<b>world)?/)
+    m.deconstruct_keys(nil).should == { a: "hello", b: nil }
+  end
+
+  it "includes non-participating captures as nil for explicit keys" do
+    m = "hello".match(/(?<a>hello)(?<b>world)?/)
+    m.deconstruct_keys([:a, :b]).should == { a: "hello", b: nil }
+  end
+
+  it "does not stop iterating at a non-participating capture" do
+    m = "hello!".match(/(?<a>hello)(?<b>world)?(?<c>!)/)
+    m.deconstruct_keys([:b, :c, :a]).should == { b: nil, c: "!", a: "hello" }
+  end
+end
diff --git a/spec/ruby/core/matchdata/deconstruct_spec.rb b/spec/ruby/core/matchdata/deconstruct_spec.rb
new file mode 100644
index 0000000000..c55095665d
--- /dev/null
+++ b/spec/ruby/core/matchdata/deconstruct_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/captures'
+
+describe "MatchData#deconstruct" do
+  it_behaves_like :matchdata_captures, :deconstruct
+end
diff --git a/spec/ruby/core/matchdata/dup_spec.rb b/spec/ruby/core/matchdata/dup_spec.rb
new file mode 100644
index 0000000000..70877f07eb
--- /dev/null
+++ b/spec/ruby/core/matchdata/dup_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+describe "MatchData#dup" do
+  it "duplicates the match data" do
+    original = /ll/.match("hello")
+    original.instance_variable_set(:@custom_ivar, 42)
+    duplicate = original.dup
+
+    duplicate.instance_variable_get(:@custom_ivar).should == 42
+    original.regexp.should == duplicate.regexp
+    original.string.should == duplicate.string
+    original.offset(0).should == duplicate.offset(0)
+  end
+end
diff --git a/spec/ruby/core/matchdata/element_reference_spec.rb b/spec/ruby/core/matchdata/element_reference_spec.rb
index 26550ac94d..5509371cd2 100644
--- a/spec/ruby/core/matchdata/element_reference_spec.rb
+++ b/spec/ruby/core/matchdata/element_reference_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#[]" do
   it "acts as normal array indexing [index]" do
@@ -15,10 +16,46 @@ describe "MatchData#[]" do
   it "supports accessors [start, length]" do
     /(.)(.)(\d+)(\d)/.match("THX1138.")[1, 2].should == %w|H X|
     /(.)(.)(\d+)(\d)/.match("THX1138.")[-3, 2].should == %w|X 113|
+
+    # negative index is larger than the number of match values
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[-30, 2].should == nil
+
+    # positive index larger than number of match values
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[5, 2].should == []
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[6, 2].should == nil
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[30, 2].should == nil
+
+    # length argument larger than number of match values is capped to match value length
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3, 10].should == %w|113 8|
+
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3, 0].should == []
+
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3, -1].should == nil
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3, -30].should == nil
   end
 
   it "supports ranges [start..end]" do
     /(.)(.)(\d+)(\d)/.match("THX1138.")[1..3].should == %w|H X 113|
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3..10].should == %w|113 8|
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[-30..2].should == nil
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3..1].should == []
+  end
+
+  it "supports endless ranges [start..]" do
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[3..].should == %w|113 8|
+  end
+
+  it "supports beginningless ranges [..end]" do
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[..1].should == %w|HX1138 H|
+  end
+
+  it "supports beginningless endless ranges [nil..nil]" do
+    /(.)(.)(\d+)(\d)/.match("THX1138.")[nil..nil].should == %w|HX1138 H X 113 8|
+  end
+
+  it "returns instances of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138.")
+    /(.)(.)(\d+)(\d)/.match(str)[0..-1].each { |m| m.should.instance_of?(String) }
   end
 end
 
@@ -71,17 +108,17 @@ describe "MatchData#[Symbol]" do
 
   it "raises an IndexError if there is no named match corresponding to the Symbol" do
     md = 'haystack'.match(/(?<t>t(?<a>ack))/)
-    -> { md[:baz] }.should raise_error(IndexError, /baz/)
+    -> { md[:baz] }.should.raise(IndexError, /baz/)
   end
 
   it "raises an IndexError if there is no named match corresponding to the String" do
     md = 'haystack'.match(/(?<t>t(?<a>ack))/)
-    -> { md['baz'] }.should raise_error(IndexError, /baz/)
+    -> { md['baz'] }.should.raise(IndexError, /baz/)
   end
 
   it "returns matches in the String's encoding" do
     rex = /(?<t>t(?<a>ack))/u
-    md = 'haystack'.force_encoding('euc-jp').match(rex)
+    md = 'haystack'.dup.force_encoding('euc-jp').match(rex)
     md[:t].encoding.should == Encoding::EUC_JP
   end
 end
diff --git a/spec/ruby/core/matchdata/end_spec.rb b/spec/ruby/core/matchdata/end_spec.rb
index d01b0a8b30..4fee24a763 100644
--- a/spec/ruby/core/matchdata/end_spec.rb
+++ b/spec/ruby/core/matchdata/end_spec.rb
@@ -12,7 +12,7 @@ describe "MatchData#end" do
 
     it "returns nil when the nth match isn't found" do
       match_data = /something is( not)? (right)/.match("something is right")
-      match_data.end(1).should be_nil
+      match_data.end(1).should == nil
     end
 
     it "returns the character offset for multi-byte strings" do
diff --git a/spec/ruby/core/matchdata/fixtures/classes.rb b/spec/ruby/core/matchdata/fixtures/classes.rb
new file mode 100644
index 0000000000..54795636e5
--- /dev/null
+++ b/spec/ruby/core/matchdata/fixtures/classes.rb
@@ -0,0 +1,3 @@
+module MatchDataSpecs
+  class MyString < String; end
+end
diff --git a/spec/ruby/core/matchdata/inspect_spec.rb b/spec/ruby/core/matchdata/inspect_spec.rb
index 5315257677..cacbe10c5d 100644
--- a/spec/ruby/core/matchdata/inspect_spec.rb
+++ b/spec/ruby/core/matchdata/inspect_spec.rb
@@ -6,7 +6,7 @@ describe "MatchData#inspect" do
   end
 
   it "returns a String" do
-    @match_data.inspect.should be_kind_of(String)
+    @match_data.inspect.should.is_a?(String)
   end
 
   it "returns a human readable representation that contains entire matched string and the captures" do
diff --git a/spec/ruby/core/matchdata/integer_at_spec.rb b/spec/ruby/core/matchdata/integer_at_spec.rb
new file mode 100644
index 0000000000..65f73a7bee
--- /dev/null
+++ b/spec/ruby/core/matchdata/integer_at_spec.rb
@@ -0,0 +1,38 @@
+# -*- encoding: utf-8 -*-
+
+require_relative '../../spec_helper'
+
+ruby_version_is "4.1" do
+  describe "MatchData#integer_at" do
+    it "converts the corresponding match to an Integer and returns it when given an Integer" do
+      md = /(\d{4})(\d{2})(\d{2})/.match("20260308")
+      md.integer_at(0).should == 20260308
+      md.integer_at(1).should == 2026
+      md.integer_at(2).should == 3
+    end
+
+    it "returns nil on non-matching index matches" do
+      md = /\b(\d)?\b/.match("THX1138.")
+      md.integer_at(1).should == nil
+    end
+
+    it "returns nil on non-integer matches" do
+      md = /(\w)?/.match("THX1138.")
+      md.integer_at(1).should == nil
+    end
+
+    it "converts the match to an Integer in the given base" do
+      md = /\w+/.match("0c")
+      md.integer_at(0).should == 0
+      md.integer_at(0, 16).should == 12
+    end
+
+    it "converts the match to an Integer in the prefix when given base is zero" do
+      /\w+/.match("010").integer_at(0, 0).should == 010
+      /\w+/.match("0x10").integer_at(0, 0).should == 0x10
+      /\w+/.match("0d10").integer_at(0, 0).should == 0d10
+      /\w+/.match("0o10").integer_at(0, 0).should == 0o10
+      /\w+/.match("0b10").integer_at(0, 0).should == 0b10
+    end
+  end
+end
diff --git a/spec/ruby/core/matchdata/match_length_spec.rb b/spec/ruby/core/matchdata/match_length_spec.rb
new file mode 100644
index 0000000000..824f94a397
--- /dev/null
+++ b/spec/ruby/core/matchdata/match_length_spec.rb
@@ -0,0 +1,32 @@
+# -*- encoding: utf-8 -*-
+
+require_relative '../../spec_helper'
+
+describe "MatchData#match_length" do
+  it "returns the length of the corresponding match when given an Integer" do
+    md = /(.)(.)(\d+)(\d)/.match("THX1138.")
+
+    md.match_length(0).should == 6
+    md.match_length(1).should == 1
+    md.match_length(2).should == 1
+    md.match_length(3).should == 3
+    md.match_length(4).should == 1
+  end
+
+  it "returns nil on non-matching index matches" do
+    md = /\d+(\w)?/.match("THX1138.")
+    md.match_length(1).should == nil
+  end
+
+  it "returns the length of the corresponding named match when given a Symbol" do
+    md = 'haystack'.match(/(?<t>t(?<a>ack))/)
+    md.match_length(:a).should == 3
+    md.match_length(:t).should == 4
+  end
+
+  it "returns nil on non-matching index matches" do
+    md = 'haystack'.match(/(?<t>t)(?<a>all)?/)
+    md.match_length(:t).should == 1
+    md.match_length(:a).should == nil
+  end
+end
diff --git a/spec/ruby/core/matchdata/match_spec.rb b/spec/ruby/core/matchdata/match_spec.rb
new file mode 100644
index 0000000000..a16914ea15
--- /dev/null
+++ b/spec/ruby/core/matchdata/match_spec.rb
@@ -0,0 +1,32 @@
+# -*- encoding: utf-8 -*-
+
+require_relative '../../spec_helper'
+
+describe "MatchData#match" do
+  it "returns the corresponding match when given an Integer" do
+    md = /(.)(.)(\d+)(\d)/.match("THX1138.")
+
+    md.match(0).should == 'HX1138'
+    md.match(1).should == 'H'
+    md.match(2).should == 'X'
+    md.match(3).should == '113'
+    md.match(4).should == '8'
+  end
+
+  it "returns nil on non-matching index matches" do
+    md = /\d+(\w)?/.match("THX1138.")
+    md.match(1).should == nil
+  end
+
+  it "returns the corresponding named match when given a Symbol" do
+    md = 'haystack'.match(/(?<t>t(?<a>ack))/)
+    md.match(:a).should == 'ack'
+    md.match(:t).should == 'tack'
+  end
+
+  it "returns nil on non-matching index matches" do
+    md = 'haystack'.match(/(?<t>t)(?<a>all)?/)
+    md.match(:t).should == 't'
+    md.match(:a).should == nil
+  end
+end
diff --git a/spec/ruby/core/matchdata/named_captures_spec.rb b/spec/ruby/core/matchdata/named_captures_spec.rb
index 9b1e324a24..10b1f884d6 100644
--- a/spec/ruby/core/matchdata/named_captures_spec.rb
+++ b/spec/ruby/core/matchdata/named_captures_spec.rb
@@ -12,4 +12,14 @@ describe 'MatchData#named_captures' do
   it 'returns the latest matched capture, even if a later one that does not match exists' do
     /\A(?<a>.)(?<b>.)(?<b>.)(?<a>.)?\z/.match('012').named_captures.should == { 'a' => '0', 'b' => '2' }
   end
+
+  it 'returns a Hash with Symbol keys when symbolize_names is provided a true value' do
+    /(?<a>.)(?<b>.)?/.match('0').named_captures(symbolize_names: true).should == { a: '0', b: nil }
+    /(?<a>.)(?<b>.)?/.match('0').named_captures(symbolize_names: "truly").should == { a: '0', b: nil }
+  end
+
+  it 'returns a Hash with String keys when symbolize_names is provided a false value' do
+    /(?<a>.)(?<b>.)?/.match('02').named_captures(symbolize_names: false).should == { 'a' => '0', 'b' => '2' }
+    /(?<a>.)(?<b>.)?/.match('02').named_captures(symbolize_names: nil).should == { 'a' => '0', 'b' => '2' }
+  end
 end
diff --git a/spec/ruby/core/matchdata/names_spec.rb b/spec/ruby/core/matchdata/names_spec.rb
index 25ca06ced9..dca15985b0 100644
--- a/spec/ruby/core/matchdata/names_spec.rb
+++ b/spec/ruby/core/matchdata/names_spec.rb
@@ -3,12 +3,12 @@ require_relative '../../spec_helper'
 describe "MatchData#names" do
   it "returns an Array" do
     md = 'haystack'.match(/(?<yellow>hay)/)
-    md.names.should be_an_instance_of(Array)
+    md.names.should.instance_of?(Array)
   end
 
   it "sets each element to a String" do
     'haystack'.match(/(?<yellow>hay)/).names.all? do |e|
-      e.should be_an_instance_of(String)
+      e.should.instance_of?(String)
     end
   end
 
diff --git a/spec/ruby/core/matchdata/offset_spec.rb b/spec/ruby/core/matchdata/offset_spec.rb
index 1ccb54b7a7..5a923d6ce0 100644
--- a/spec/ruby/core/matchdata/offset_spec.rb
+++ b/spec/ruby/core/matchdata/offset_spec.rb
@@ -1,30 +1,102 @@
-# -*- encoding: utf-8 -*-
-
 require_relative '../../spec_helper'
 
 describe "MatchData#offset" do
-  it "returns a two element array with the begin and end of the nth match" do
-    match_data = /(.)(.)(\d+)(\d)/.match("THX1138.")
-    match_data.offset(0).should == [1, 7]
-    match_data.offset(4).should == [6, 7]
+  it "returns beginning and ending character offset of whole matched substring for 0 element" do
+    m = /(.)(.)(\d+)(\d)/.match("THX1138.")
+    m.offset(0).should == [1, 7]
+  end
+
+  it "returns beginning and ending character offset of n-th match, all the subsequent elements are capturing groups" do
+    m = /(.)(.)(\d+)(\d)/.match("THX1138.")
+
+    m.offset(2).should == [2, 3]
+    m.offset(3).should == [3, 6]
+    m.offset(4).should == [6, 7]
+  end
+
+  it "accepts String as a reference to a named capture" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.offset("f").should == [0, 3]
+    m.offset("b").should == [3, 6]
+  end
+
+  it "accepts Symbol as a reference to a named capture" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    m.offset(:f).should == [0, 3]
+    m.offset(:b).should == [3, 6]
   end
 
-  it "returns [nil, nil] when the nth match isn't found" do
-    match_data = /something is( not)? (right)/.match("something is right")
-    match_data.offset(1).should == [nil, nil]
+  it "returns [nil, nil] if a capturing group is optional and doesn't match" do
+    m = /(?<x>q..)?/.match("foobarbaz")
+
+    m.offset("x").should == [nil, nil]
+    m.offset(1).should == [nil, nil]
   end
 
-  it "returns the offset for multi byte strings" do
-    match_data = /(.)(.)(\d+)(\d)/.match("TñX1138.")
-    match_data.offset(0).should == [1, 7]
-    match_data.offset(4).should == [6, 7]
+  it "returns correct beginning and ending character offset for multi-byte strings" do
+    m = /\A\u3042(.)(.)?(.)\z/.match("\u3042\u3043\u3044")
+
+    m.offset(1).should == [1, 2]
+    m.offset(3).should == [2, 3]
   end
 
   not_supported_on :opal do
-    it "returns the offset for multi byte strings with unicode regexp" do
-      match_data = /(.)(.)(\d+)(\d)/u.match("TñX1138.")
-      match_data.offset(0).should == [1, 7]
-      match_data.offset(4).should == [6, 7]
+    it "returns correct character offset for multi-byte strings with unicode regexp" do
+      m = /\A\u3042(.)(.)?(.)\z/u.match("\u3042\u3043\u3044")
+
+      m.offset(1).should == [1, 2]
+      m.offset(3).should == [2, 3]
     end
   end
+
+  it "returns [nil, nil] if a capturing group is optional and doesn't match for multi-byte string" do
+    m = /\A\u3042(.)(.)?(.)\z/.match("\u3042\u3043\u3044")
+
+    m.offset(2).should == [nil, nil]
+  end
+
+  it "converts argument into integer if is not String nor Symbol" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    obj = Object.new
+    def obj.to_int; 2; end
+
+    m.offset(1r).should == [0, 3]
+    m.offset(1.1).should == [0, 3]
+    m.offset(obj).should == [3, 6]
+  end
+
+  it "raises IndexError if there is no group with the provided name" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.offset("y")
+    }.should.raise(IndexError, "undefined group name reference: y")
+
+    -> {
+      m.offset(:y)
+    }.should.raise(IndexError, "undefined group name reference: y")
+  end
+
+  it "raises IndexError if index is out of bounds" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.offset(-1)
+    }.should.raise(IndexError, "index -1 out of matches")
+
+    -> {
+      m.offset(3)
+    }.should.raise(IndexError, "index 3 out of matches")
+  end
+
+  it "raises TypeError if can't convert argument into Integer" do
+    m = /(?<f>foo)(?<b>bar)/.match("foobar")
+
+    -> {
+      m.offset([])
+    }.should.raise(TypeError, "no implicit conversion of Array into Integer")
+  end
 end
diff --git a/spec/ruby/core/matchdata/post_match_spec.rb b/spec/ruby/core/matchdata/post_match_spec.rb
index 6e13438124..b50d637124 100644
--- a/spec/ruby/core/matchdata/post_match_spec.rb
+++ b/spec/ruby/core/matchdata/post_match_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#post_match" do
   it "returns the string after the match equiv. special var $'" do
@@ -6,29 +7,18 @@ describe "MatchData#post_match" do
     $'.should == ': The Movie'
   end
 
-  it "keeps taint status from the source string" do
-    str = "THX1138: The Movie"
-    str.taint
-    res = /(.)(.)(\d+)(\d)/.match(str).post_match
-    res.tainted?.should be_true
-    $'.tainted?.should be_true
-  end
-
-  it "keeps untrusted status from the source string" do
-    str = "THX1138: The Movie"
-    str.untrust
-    res = /(.)(.)(\d+)(\d)/.match(str).post_match
-    res.untrusted?.should be_true
-    $'.untrusted?.should be_true
-  end
-
   it "sets the encoding to the encoding of the source String" do
-    str = "abc".force_encoding Encoding::EUC_JP
-    str.match(/b/).post_match.encoding.should equal(Encoding::EUC_JP)
+    str = "abc".dup.force_encoding Encoding::EUC_JP
+    str.match(/b/).post_match.encoding.should.equal?(Encoding::EUC_JP)
   end
 
   it "sets an empty result to the encoding of the source String" do
-    str = "abc".force_encoding Encoding::ISO_8859_1
-    str.match(/c/).post_match.encoding.should equal(Encoding::ISO_8859_1)
+    str = "abc".dup.force_encoding Encoding::ISO_8859_1
+    str.match(/c/).post_match.encoding.should.equal?(Encoding::ISO_8859_1)
+  end
+
+  it "returns an instance of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+    /(.)(.)(\d+)(\d)/.match(str).post_match.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/core/matchdata/pre_match_spec.rb b/spec/ruby/core/matchdata/pre_match_spec.rb
index 816cc91eb2..106612a4f7 100644
--- a/spec/ruby/core/matchdata/pre_match_spec.rb
+++ b/spec/ruby/core/matchdata/pre_match_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#pre_match" do
   it "returns the string before the match, equiv. special var $`" do
@@ -6,29 +7,18 @@ describe "MatchData#pre_match" do
     $`.should == 'T'
   end
 
-  it "keeps taint status from the source string" do
-    str = "THX1138: The Movie"
-    str.taint
-    res = /(.)(.)(\d+)(\d)/.match(str).pre_match
-    res.tainted?.should be_true
-    $`.tainted?.should be_true
-  end
-
-  it "keeps untrusted status from the source string" do
-    str = "THX1138: The Movie"
-    str.untrust
-    res = /(.)(.)(\d+)(\d)/.match(str).pre_match
-    res.untrusted?.should be_true
-    $`.untrusted?.should be_true
-  end
-
   it "sets the encoding to the encoding of the source String" do
-    str = "abc".force_encoding Encoding::EUC_JP
-    str.match(/b/).pre_match.encoding.should equal(Encoding::EUC_JP)
+    str = "abc".dup.force_encoding Encoding::EUC_JP
+    str.match(/b/).pre_match.encoding.should.equal?(Encoding::EUC_JP)
   end
 
   it "sets an empty result to the encoding of the source String" do
-    str = "abc".force_encoding Encoding::ISO_8859_1
-    str.match(/a/).pre_match.encoding.should equal(Encoding::ISO_8859_1)
+    str = "abc".dup.force_encoding Encoding::ISO_8859_1
+    str.match(/a/).pre_match.encoding.should.equal?(Encoding::ISO_8859_1)
+  end
+
+  it "returns an instance of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+    /(.)(.)(\d+)(\d)/.match(str).pre_match.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/core/matchdata/regexp_spec.rb b/spec/ruby/core/matchdata/regexp_spec.rb
index 05a8e80567..7dcb0e62db 100644
--- a/spec/ruby/core/matchdata/regexp_spec.rb
+++ b/spec/ruby/core/matchdata/regexp_spec.rb
@@ -3,11 +3,22 @@ require_relative '../../spec_helper'
 describe "MatchData#regexp" do
   it "returns a Regexp object" do
     m = 'haystack'.match(/hay/)
-    m.regexp.should be_an_instance_of(Regexp)
+    m.regexp.should.instance_of?(Regexp)
   end
 
   it "returns the pattern used in the match" do
     m = 'haystack'.match(/hay/)
     m.regexp.should == /hay/
   end
+
+  it "returns the same Regexp used to match" do
+    r = /hay/
+    m = 'haystack'.match(r)
+    m.regexp.object_id.should == r.object_id
+  end
+
+  it "returns a Regexp for the result of gsub(String)" do
+    'he[[o'.gsub('[', ']')
+    $~.regexp.should == /\[/
+  end
 end
diff --git a/spec/ruby/core/matchdata/shared/captures.rb b/spec/ruby/core/matchdata/shared/captures.rb
new file mode 100644
index 0000000000..de5870f543
--- /dev/null
+++ b/spec/ruby/core/matchdata/shared/captures.rb
@@ -0,0 +1,13 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe :matchdata_captures, shared: true do
+  it "returns an array of the match captures" do
+    /(.)(.)(\d+)(\d)/.match("THX1138.").send(@method).should == ["H","X","113","8"]
+  end
+
+  it "returns instances of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138: The Movie")
+    /(.)(.)(\d+)(\d)/.match(str).send(@method).each { |c| c.should.instance_of?(String) }
+  end
+end
diff --git a/spec/ruby/core/matchdata/shared/eql.rb b/spec/ruby/core/matchdata/shared/eql.rb
index e021baa178..e4bb8797b7 100644
--- a/spec/ruby/core/matchdata/shared/eql.rb
+++ b/spec/ruby/core/matchdata/shared/eql.rb
@@ -4,23 +4,23 @@ describe :matchdata_eql, shared: true do
   it "returns true if both operands have equal target strings, patterns, and match positions" do
     a = 'haystack'.match(/hay/)
     b = 'haystack'.match(/hay/)
-    a.send(@method, b).should be_true
+    a.send(@method, b).should == true
   end
 
   it "returns false if the operands have different target strings" do
     a = 'hay'.match(/hay/)
     b = 'haystack'.match(/hay/)
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
   end
 
   it "returns false if the operands have different patterns" do
     a = 'haystack'.match(/h.y/)
     b = 'haystack'.match(/hay/)
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
   end
 
   it "returns false if the argument is not a MatchData object" do
     a = 'haystack'.match(/hay/)
-    a.send(@method, Object.new).should be_false
+    a.send(@method, Object.new).should == false
   end
 end
diff --git a/spec/ruby/core/matchdata/string_spec.rb b/spec/ruby/core/matchdata/string_spec.rb
index ff1b4eab5b..50bbb5a64f 100644
--- a/spec/ruby/core/matchdata/string_spec.rb
+++ b/spec/ruby/core/matchdata/string_spec.rb
@@ -9,6 +9,18 @@ describe "MatchData#string" do
   it "returns a frozen copy of the match string" do
     str = /(.)(.)(\d+)(\d)/.match("THX1138.").string
     str.should == "THX1138."
-    str.frozen?.should == true
+    str.should.frozen?
+  end
+
+  it "returns the same frozen string for every call" do
+    md = /(.)(.)(\d+)(\d)/.match("THX1138.")
+    md.string.should.equal?(md.string)
+  end
+
+  it "returns a frozen copy of the matched string for gsub!(String)" do
+    s = +'he[[o'
+    s.gsub!('[', ']')
+    $~.string.should == 'he[[o'
+    $~.string.should.frozen?
   end
 end
diff --git a/spec/ruby/core/matchdata/to_a_spec.rb b/spec/ruby/core/matchdata/to_a_spec.rb
index 6231d096fb..c77fc4ab37 100644
--- a/spec/ruby/core/matchdata/to_a_spec.rb
+++ b/spec/ruby/core/matchdata/to_a_spec.rb
@@ -1,7 +1,13 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#to_a" do
   it "returns an array of matches" do
     /(.)(.)(\d+)(\d)/.match("THX1138.").to_a.should == ["HX1138", "H", "X", "113", "8"]
   end
+
+  it "returns instances of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138.")
+    /(.)(.)(\d+)(\d)/.match(str)[0..-1].to_a.each { |m| m.should.instance_of?(String) }
+  end
 end
diff --git a/spec/ruby/core/matchdata/to_s_spec.rb b/spec/ruby/core/matchdata/to_s_spec.rb
index 9e213bb342..cbcc5e8a21 100644
--- a/spec/ruby/core/matchdata/to_s_spec.rb
+++ b/spec/ruby/core/matchdata/to_s_spec.rb
@@ -1,7 +1,13 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "MatchData#to_s" do
   it "returns the entire matched string" do
     /(.)(.)(\d+)(\d)/.match("THX1138.").to_s.should == "HX1138"
   end
+
+  it "returns an instance of String when given a String subclass" do
+    str = MatchDataSpecs::MyString.new("THX1138.")
+    /(.)(.)(\d+)(\d)/.match(str).to_s.should.instance_of?(String)
+  end
 end
diff --git a/spec/ruby/core/matchdata/values_at_spec.rb b/spec/ruby/core/matchdata/values_at_spec.rb
index 8f7fdf557c..ba5b0e662c 100644
--- a/spec/ruby/core/matchdata/values_at_spec.rb
+++ b/spec/ruby/core/matchdata/values_at_spec.rb
@@ -1,21 +1,76 @@
 require_relative '../../spec_helper'
 
 describe "MatchData#values_at" do
-  it "returns an array of the matching value" do
-    /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(0, 2, -2).should == ["HX1138", "X", "113"]
+  # Should be synchronized with core/array/values_at_spec.rb and core/struct/values_at_spec.rb
+  #
+  # /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").to_a # => ["HX1138", "H", "X", "113", "8"]
+
+  context "when passed a list of Integers" do
+    it "returns an array containing each value given by one of integers" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(0, 2, -2).should == ["HX1138", "X", "113"]
+    end
+
+    it "returns nil value for any integer that is out of range" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(5).should == [nil]
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(-6).should == [nil]
+    end
   end
 
-  describe "when passed a Range" do
-    it "returns an array of the matching value" do
-      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(2..4, 0..1).should == ["X", "113", "8", "HX1138", "H"]
+  context "when passed an integer Range" do
+    it "returns an array containing each value given by the elements of the range" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(0..2).should == ["HX1138", "H", "X"]
+    end
+
+    it "fills with nil values for range elements larger than the captured values number" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(0..5).should == ["HX1138", "H", "X", "113", "8", nil]
+    end
+
+    it "raises RangeError if any element of the range is negative and out of range" do
+      -> { /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(-6..3) }.should.raise(RangeError, "-6..3 out of range")
+    end
+
+    it "supports endless Range" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(0..).should == ["HX1138", "H", "X", "113", "8"]
+    end
+
+    it "supports beginningless Range" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(..2).should == ["HX1138", "H", "X"]
+    end
+
+    it "returns an empty Array when Range is empty" do
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(2..0).should == []
+    end
+  end
+
+  context "when passed names" do
+    it 'slices captures with the given names' do
+      /(?<a>.)(?<b>.)(?<c>.)/.match('012').values_at(:c, :a).should == ['2', '0']
+    end
+
+    it 'slices captures with the given String names' do
+      /(?<a>.)(?<b>.)(?<c>.)/.match('012').values_at('c', 'a').should == ['2', '0']
     end
   end
 
-  it 'slices captures with the given names' do
-    /(?<a>.)(?<b>.)(?<c>.)/.match('012').values_at(:c, :a).should == ['2', '0']
+  it "supports multiple integer Ranges" do
+    /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(1..2, 2..3).should == ["H", "X", "X", "113"]
   end
 
-  it 'takes names and indices' do
+  it "supports mixing integer Ranges and Integers" do
+    /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(1..2, 4).should == ["H", "X", "8"]
+  end
+
+  it 'supports mixing of names and indices' do
     /\A(?<a>.)(?<b>.)\z/.match('01').values_at(0, 1, 2, :a, :b).should == ['01', '0', '1', '0', '1']
   end
+
+  it "returns a new empty Array if no arguments given" do
+    /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at().should == []
+  end
+
+  it "fails when passed arguments of unsupported types" do
+    -> {
+      /(.)(.)(\d+)(\d)/.match("THX1138: The Movie").values_at(Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+  end
 end
diff --git a/spec/ruby/core/math/acos_spec.rb b/spec/ruby/core/math/acos_spec.rb
index 8b321ab29b..4649dc527c 100644
--- a/spec/ruby/core/math/acos_spec.rb
+++ b/spec/ruby/core/math/acos_spec.rb
@@ -8,7 +8,7 @@ describe "Math.acos" do
   end
 
   it "returns a float" do
-    Math.acos(1).should be_kind_of(Float )
+    Math.acos(1).should.is_a?(Float )
   end
 
   it "returns the arccosine of the argument" do
@@ -21,27 +21,27 @@ describe "Math.acos" do
   end
 
   it "raises an Math::DomainError if the argument is greater than 1.0" do
-    -> { Math.acos(1.0001) }.should raise_error(Math::DomainError)
+    -> { Math.acos(1.0001) }.should.raise(Math::DomainError)
   end
 
   it "raises an Math::DomainError if the argument is less than -1.0" do
-    -> { Math.acos(-1.0001) }.should raise_error(Math::DomainError)
+    -> { Math.acos(-1.0001) }.should.raise(Math::DomainError)
   end
 
   it "raises a TypeError if the string argument cannot be coerced with Float()" do
-    -> { Math.acos("test") }.should raise_error(TypeError)
+    -> { Math.acos("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.acos(nan_value).nan?.should be_true
+    Math.acos(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.acos(MathSpecs::UserClass.new) }.should raise_error(TypeError)
+    -> { Math.acos(MathSpecs::UserClass.new) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.acos(nil) }.should raise_error(TypeError)
+    -> { Math.acos(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/acosh_spec.rb b/spec/ruby/core/math/acosh_spec.rb
index 6707de95d3..ccacda37e0 100644
--- a/spec/ruby/core/math/acosh_spec.rb
+++ b/spec/ruby/core/math/acosh_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.acosh" do
   it "returns a float" do
-    Math.acosh(1.0).should be_kind_of(Float)
+    Math.acosh(1.0).should.is_a?(Float)
   end
 
   it "returns the principle value of the inverse hyperbolic cosine of the argument" do
@@ -12,21 +12,21 @@ describe "Math.acosh" do
   end
 
   it "raises Math::DomainError if the passed argument is less than -1.0 or greater than 1.0" do
-    -> { Math.acosh(1.0 - TOLERANCE) }.should raise_error(Math::DomainError)
-    -> { Math.acosh(0) }.should raise_error(Math::DomainError)
-    -> { Math.acosh(-1.0) }.should raise_error(Math::DomainError)
+    -> { Math.acosh(1.0 - TOLERANCE) }.should.raise(Math::DomainError)
+    -> { Math.acosh(0) }.should.raise(Math::DomainError)
+    -> { Math.acosh(-1.0) }.should.raise(Math::DomainError)
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.acosh("test") }.should raise_error(TypeError)
+    -> { Math.acosh("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.acosh(nan_value).nan?.should be_true
+    Math.acosh(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.acosh(nil) }.should raise_error(TypeError)
+    -> { Math.acosh(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/asin_spec.rb b/spec/ruby/core/math/asin_spec.rb
index 3a674a1147..1386bccc06 100644
--- a/spec/ruby/core/math/asin_spec.rb
+++ b/spec/ruby/core/math/asin_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # arcsine : (-1.0, 1.0) --> (-PI/2, PI/2)
 describe "Math.asin" do
   it "returns a float" do
-    Math.asin(1).should be_kind_of(Float)
+    Math.asin(1).should.is_a?(Float)
   end
 
   it "returns the arcsine of the argument" do
@@ -17,23 +17,23 @@ describe "Math.asin" do
   end
 
   it "raises an Math::DomainError if the argument is greater than 1.0" do
-    -> { Math.asin(1.0001) }.should raise_error( Math::DomainError)
+    -> { Math.asin(1.0001) }.should.raise( Math::DomainError)
   end
 
   it "raises an Math::DomainError if the argument is less than -1.0" do
-    -> { Math.asin(-1.0001) }.should raise_error( Math::DomainError)
+    -> { Math.asin(-1.0001) }.should.raise( Math::DomainError)
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.asin("test") }.should raise_error(TypeError)
+    -> { Math.asin("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.asin(nan_value).nan?.should be_true
+    Math.asin(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.asin(nil) }.should raise_error(TypeError)
+    -> { Math.asin(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/asinh_spec.rb b/spec/ruby/core/math/asinh_spec.rb
index ff8210df0a..8aa019f05f 100644
--- a/spec/ruby/core/math/asinh_spec.rb
+++ b/spec/ruby/core/math/asinh_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.asinh" do
   it "returns a float" do
-    Math.asinh(1.5).should be_kind_of(Float)
+    Math.asinh(1.5).should.is_a?(Float)
   end
 
   it "returns the inverse hyperbolic sin of the argument" do
@@ -19,15 +19,15 @@ describe "Math.asinh" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.asinh("test") }.should raise_error(TypeError)
+    -> { Math.asinh("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.asinh(nan_value).nan?.should be_true
+    Math.asinh(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.asinh(nil) }.should raise_error(TypeError)
+    -> { Math.asinh(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/atan2_spec.rb b/spec/ruby/core/math/atan2_spec.rb
index d4ef369d2a..1f1de506c5 100644
--- a/spec/ruby/core/math/atan2_spec.rb
+++ b/spec/ruby/core/math/atan2_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.atan2" do
   it "returns a float" do
-    Math.atan2(1.2, 0.5).should be_kind_of(Float)
+    Math.atan2(1.2, 0.5).should.is_a?(Float)
   end
 
   it "returns the arc tangent of y, x" do
@@ -14,15 +14,15 @@ describe "Math.atan2" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.atan2(1.0, "test")    }.should raise_error(TypeError)
-    -> { Math.atan2("test", 0.0)    }.should raise_error(TypeError)
-    -> { Math.atan2("test", "this") }.should raise_error(TypeError)
+    -> { Math.atan2(1.0, "test")    }.should.raise(TypeError)
+    -> { Math.atan2("test", 0.0)    }.should.raise(TypeError)
+    -> { Math.atan2("test", "this") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.atan2(nil, 1.0)  }.should raise_error(TypeError)
-    -> { Math.atan2(-1.0, nil) }.should raise_error(TypeError)
-    -> { Math.atan2(nil, nil)  }.should raise_error(TypeError)
+    -> { Math.atan2(nil, 1.0)  }.should.raise(TypeError)
+    -> { Math.atan2(-1.0, nil) }.should.raise(TypeError)
+    -> { Math.atan2(nil, nil)  }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/atan_spec.rb b/spec/ruby/core/math/atan_spec.rb
index 15edf68c05..07d04cdf82 100644
--- a/spec/ruby/core/math/atan_spec.rb
+++ b/spec/ruby/core/math/atan_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # arctangent : (-Inf, Inf) --> (-PI/2, PI/2)
 describe "Math.atan" do
   it "returns a float" do
-    Math.atan(1).should be_kind_of(Float)
+    Math.atan(1).should.is_a?(Float)
   end
 
   it "returns the arctangent of the argument" do
@@ -17,15 +17,15 @@ describe "Math.atan" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.atan("test") }.should raise_error(TypeError)
+    -> { Math.atan("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.atan(nan_value).nan?.should be_true
+    Math.atan(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.atan(nil) }.should raise_error(TypeError)
+    -> { Math.atan(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/atanh_spec.rb b/spec/ruby/core/math/atanh_spec.rb
index 21fb209941..edcb8f2e52 100644
--- a/spec/ruby/core/math/atanh_spec.rb
+++ b/spec/ruby/core/math/atanh_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
-require_relative '../../fixtures/math/common'
-require_relative '../../shared/math/atanh'
+require_relative 'fixtures/common'
+require_relative 'shared/atanh'
 
 describe "Math.atanh" do
   it_behaves_like :math_atanh_base, :atanh, Math
diff --git a/spec/ruby/core/math/cbrt_spec.rb b/spec/ruby/core/math/cbrt_spec.rb
index 01cf923c71..4e2383043b 100644
--- a/spec/ruby/core/math/cbrt_spec.rb
+++ b/spec/ruby/core/math/cbrt_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.cbrt" do
   it "returns a float" do
-    Math.cbrt(1).should be_an_instance_of(Float)
+    Math.cbrt(1).should.instance_of?(Float)
   end
 
   it "returns the cubic root of the argument" do
@@ -14,11 +14,11 @@ describe "Math.cbrt" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.cbrt("foobar") }.should raise_error(TypeError)
+    -> { Math.cbrt("foobar") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.cbrt(nil) }.should raise_error(TypeError)
+    -> { Math.cbrt(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/cos_spec.rb b/spec/ruby/core/math/cos_spec.rb
index 3ba7a54c38..e8602cde3c 100644
--- a/spec/ruby/core/math/cos_spec.rb
+++ b/spec/ruby/core/math/cos_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # cosine : (-Inf, Inf) --> (-1.0, 1.0)
 describe "Math.cos" do
   it "returns a float" do
-    Math.cos(Math::PI).should be_kind_of(Float)
+    Math.cos(Math::PI).should.is_a?(Float)
   end
 
   it "returns the cosine of the argument expressed in radians" do
@@ -15,23 +15,31 @@ describe "Math.cos" do
     Math.cos(2*Math::PI).should be_close(1.0, TOLERANCE)
   end
 
-
   it "raises a TypeError unless the argument is Numeric and has #to_f" do
-    -> { Math.cos("test") }.should raise_error(TypeError)
+    -> { Math.cos("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.cos(nan_value).nan?.should be_true
-  end
-
-  it "raises a TypeError if the argument is nil" do
-    -> { Math.cos(nil) }.should raise_error(TypeError)
+    Math.cos(nan_value).nan?.should == true
   end
 
-  it "coerces its argument with #to_f" do
-    f = mock_numeric('8.2')
-    f.should_receive(:to_f).and_return(8.2)
-    Math.cos(f).should == Math.cos(8.2)
+  describe "coerces its argument with #to_f" do
+    it "coerces its argument with #to_f" do
+      f = mock_numeric('8.2')
+      f.should_receive(:to_f).and_return(8.2)
+      Math.cos(f).should == Math.cos(8.2)
+    end
+
+    it "raises a TypeError if the given argument can't be converted to a Float" do
+      -> { Math.cos(nil) }.should.raise(TypeError)
+      -> { Math.cos(:abc) }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to a Float" do
+      object = mock_numeric('mock-float')
+      object.should_receive(:to_f).and_raise(NoMethodError)
+      -> { Math.cos(object) }.should.raise(NoMethodError)
+    end
   end
 end
 
diff --git a/spec/ruby/core/math/cosh_spec.rb b/spec/ruby/core/math/cosh_spec.rb
index 049e117e56..2093d8a74a 100644
--- a/spec/ruby/core/math/cosh_spec.rb
+++ b/spec/ruby/core/math/cosh_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.cosh" do
   it "returns a float" do
-    Math.cosh(1.0).should be_kind_of(Float)
+    Math.cosh(1.0).should.is_a?(Float)
   end
 
   it "returns the hyperbolic cosine of the argument" do
@@ -14,15 +14,15 @@ describe "Math.cosh" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.cosh("test") }.should raise_error(TypeError)
+    -> { Math.cosh("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.cosh(nan_value).nan?.should be_true
+    Math.cosh(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.cosh(nil) }.should raise_error(TypeError)
+    -> { Math.cosh(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/erf_spec.rb b/spec/ruby/core/math/erf_spec.rb
index b4e6248e43..5384e73ae9 100644
--- a/spec/ruby/core/math/erf_spec.rb
+++ b/spec/ruby/core/math/erf_spec.rb
@@ -5,7 +5,7 @@ require_relative 'fixtures/classes'
 # distribution (which is a normalized form of the Gaussian function).
 describe "Math.erf" do
   it "returns a float" do
-    Math.erf(1).should be_kind_of(Float)
+    Math.erf(1).should.is_a?(Float)
   end
 
   it "returns the error function of the argument" do
@@ -21,15 +21,15 @@ describe "Math.erf" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.erf("test") }.should raise_error(TypeError)
+    -> { Math.erf("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.erf(nan_value).nan?.should be_true
+    Math.erf(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.erf(nil) }.should raise_error(TypeError)
+    -> { Math.erf(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/erfc_spec.rb b/spec/ruby/core/math/erfc_spec.rb
index e465f5cf58..4e09a68d1e 100644
--- a/spec/ruby/core/math/erfc_spec.rb
+++ b/spec/ruby/core/math/erfc_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # erfc is the complementary error function
 describe "Math.erfc" do
   it "returns a float" do
-    Math.erf(1).should be_kind_of(Float)
+    Math.erf(1).should.is_a?(Float)
   end
 
   it "returns the complementary error function of the argument" do
@@ -20,15 +20,15 @@ describe "Math.erfc" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.erfc("test") }.should raise_error(TypeError)
+    -> { Math.erfc("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.erfc(nan_value).nan?.should be_true
+    Math.erfc(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.erfc(nil) }.should raise_error(TypeError)
+    -> { Math.erfc(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/exp_spec.rb b/spec/ruby/core/math/exp_spec.rb
index 36eb49a8c7..3688482457 100644
--- a/spec/ruby/core/math/exp_spec.rb
+++ b/spec/ruby/core/math/exp_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.exp" do
   it "returns a float" do
-    Math.exp(1.0).should be_kind_of(Float)
+    Math.exp(1.0).should.is_a?(Float)
   end
 
   it "returns the base-e exponential of the argument" do
@@ -14,15 +14,15 @@ describe "Math.exp" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.exp("test") }.should raise_error(TypeError)
+    -> { Math.exp("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.exp(nan_value).nan?.should be_true
+    Math.exp(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.exp(nil) }.should raise_error(TypeError)
+    -> { Math.exp(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/expm1_spec.rb b/spec/ruby/core/math/expm1_spec.rb
new file mode 100644
index 0000000000..35f62b5dbd
--- /dev/null
+++ b/spec/ruby/core/math/expm1_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "4.0" do
+  describe "Math.expm1" do
+    it "calculates Math.exp(arg) - 1" do
+      Math.expm1(3).should == Math.exp(3) - 1
+    end
+
+    it "preserves precision that can be lost otherwise" do
+      Math.expm1(1.0e-16).should be_close(1.0e-16, TOLERANCE)
+      Math.expm1(1.0e-16).should != 0.0
+    end
+
+    it "raises a TypeError if the argument cannot be coerced with Float()" do
+      -> { Math.expm1("test") }.should.raise(TypeError, "can't convert String into Float")
+    end
+
+    it "returns NaN given NaN" do
+      Math.expm1(nan_value).nan?.should == true
+    end
+
+    it "raises a TypeError if the argument is nil" do
+      -> { Math.expm1(nil) }.should.raise(TypeError, "can't convert nil into Float")
+    end
+
+    it "accepts any argument that can be coerced with Float()" do
+      Math.expm1(MathSpecs::Float.new).should be_close(Math::E - 1, TOLERANCE)
+    end
+  end
+
+  describe "Math#expm1" do
+    it "is accessible as a private instance method" do
+      IncludesMath.new.send(:expm1, 23.1415).should be_close(11226018483.0012, TOLERANCE)
+    end
+  end
+end
diff --git a/spec/ruby/fixtures/math/common.rb b/spec/ruby/core/math/fixtures/common.rb
index 024732fa7a..024732fa7a 100644
--- a/spec/ruby/fixtures/math/common.rb
+++ b/spec/ruby/core/math/fixtures/common.rb
diff --git a/spec/ruby/core/math/frexp_spec.rb b/spec/ruby/core/math/frexp_spec.rb
index 7dfb493d20..6853e4672f 100644
--- a/spec/ruby/core/math/frexp_spec.rb
+++ b/spec/ruby/core/math/frexp_spec.rb
@@ -9,16 +9,16 @@ describe "Math.frexp" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.frexp("test") }.should raise_error(TypeError)
+    -> { Math.frexp("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
     frac, _exp = Math.frexp(nan_value)
-    frac.nan?.should be_true
+    frac.nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.frexp(nil) }.should raise_error(TypeError)
+    -> { Math.frexp(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/gamma_spec.rb b/spec/ruby/core/math/gamma_spec.rb
index 386162a087..9a0b14448a 100644
--- a/spec/ruby/core/math/gamma_spec.rb
+++ b/spec/ruby/core/math/gamma_spec.rb
@@ -51,7 +51,7 @@ describe "Math.gamma" do
   end
 
   it "raises Math::DomainError given -1" do
-    -> { Math.gamma(-1) }.should raise_error(Math::DomainError)
+    -> { Math.gamma(-1) }.should.raise(Math::DomainError)
   end
 
   # See https://bugs.ruby-lang.org/issues/10642
@@ -60,10 +60,10 @@ describe "Math.gamma" do
   end
 
   it "raises Math::DomainError given negative infinity" do
-    -> { Math.gamma(-Float::INFINITY) }.should raise_error(Math::DomainError)
+    -> { Math.gamma(-Float::INFINITY) }.should.raise(Math::DomainError)
   end
 
   it "returns NaN given NaN" do
-    Math.gamma(nan_value).nan?.should be_true
+    Math.gamma(nan_value).nan?.should == true
   end
 end
diff --git a/spec/ruby/core/math/hypot_spec.rb b/spec/ruby/core/math/hypot_spec.rb
index 3e0ce74597..4ab5bd4e88 100644
--- a/spec/ruby/core/math/hypot_spec.rb
+++ b/spec/ruby/core/math/hypot_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.hypot" do
   it "returns a float" do
-    Math.hypot(3, 4).should be_kind_of(Float)
+    Math.hypot(3, 4).should.is_a?(Float)
   end
 
   it "returns the length of the hypotenuse of a right triangle with legs given by the arguments" do
@@ -16,17 +16,17 @@ describe "Math.hypot" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.hypot("test", "this") }.should raise_error(TypeError)
+    -> { Math.hypot("test", "this") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.hypot(nan_value, 0).nan?.should be_true
-    Math.hypot(0, nan_value).nan?.should be_true
-    Math.hypot(nan_value, nan_value).nan?.should be_true
+    Math.hypot(nan_value, 0).nan?.should == true
+    Math.hypot(0, nan_value).nan?.should == true
+    Math.hypot(nan_value, nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.hypot(nil, nil) }.should raise_error(TypeError)
+    -> { Math.hypot(nil, nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/ldexp_spec.rb b/spec/ruby/core/math/ldexp_spec.rb
index fb7799cf26..1864b7455a 100644
--- a/spec/ruby/core/math/ldexp_spec.rb
+++ b/spec/ruby/core/math/ldexp_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.ldexp" do
   it "returns a float" do
-    Math.ldexp(1.0, 2).should be_kind_of(Float)
+    Math.ldexp(1.0, 2).should.is_a?(Float)
   end
 
   it "returns the argument multiplied by 2**n" do
@@ -15,27 +15,27 @@ describe "Math.ldexp" do
   end
 
   it "raises a TypeError if the first argument cannot be coerced with Float()" do
-    -> { Math.ldexp("test", 2) }.should raise_error(TypeError)
+    -> { Math.ldexp("test", 2) }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.ldexp(nan_value, 0).nan?.should be_true
+    Math.ldexp(nan_value, 0).nan?.should == true
   end
 
   it "raises RangeError if NaN is given as the second arg" do
-    -> { Math.ldexp(0, nan_value) }.should raise_error(RangeError)
+    -> { Math.ldexp(0, nan_value) }.should.raise(RangeError)
   end
 
   it "raises a TypeError if the second argument cannot be coerced with Integer()" do
-    -> { Math.ldexp(3.2, "this") }.should raise_error(TypeError)
+    -> { Math.ldexp(3.2, "this") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the first argument is nil" do
-    -> { Math.ldexp(nil, 2) }.should raise_error(TypeError)
+    -> { Math.ldexp(nil, 2) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the second argument is nil" do
-    -> { Math.ldexp(3.1, nil) }.should raise_error(TypeError)
+    -> { Math.ldexp(3.1, nil) }.should.raise(TypeError)
   end
 
   it "accepts any first argument that can be coerced with Float()" do
@@ -45,6 +45,12 @@ describe "Math.ldexp" do
   it "accepts any second argument that can be coerced with Integer()" do
     Math.ldexp(3.23, MathSpecs::Integer.new).should be_close(12.92, TOLERANCE)
   end
+
+  it "returns correct value that closes to the max value of double type" do
+    Math.ldexp(0.5122058490966879, 1024).should == 9.207889385574391e+307
+    Math.ldexp(0.9999999999999999, 1024).should == 1.7976931348623157e+308
+    Math.ldexp(0.99999999999999999, 1024).should == Float::INFINITY
+  end
 end
 
 describe "Math#ldexp" do
diff --git a/spec/ruby/core/math/lgamma_spec.rb b/spec/ruby/core/math/lgamma_spec.rb
index 33e7836448..38f07d0bf8 100644
--- a/spec/ruby/core/math/lgamma_spec.rb
+++ b/spec/ruby/core/math/lgamma_spec.rb
@@ -5,10 +5,8 @@ describe "Math.lgamma" do
     Math.lgamma(0).should == [infinity_value, 1]
   end
 
-  platform_is_not :windows do
-    it "returns [Infinity, 1] when passed -1" do
-      Math.lgamma(-1).should == [infinity_value, 1]
-    end
+  it "returns [Infinity, ...] when passed -1" do
+    Math.lgamma(-1)[0].should == infinity_value
   end
 
   it "returns [Infinity, -1] when passed -0.0" do
@@ -40,15 +38,14 @@ describe "Math.lgamma" do
   end
 
   it "raises Math::DomainError when passed -Infinity" do
-    -> { Math.lgamma(-infinity_value) }.should raise_error(Math::DomainError)
+    -> { Math.lgamma(-infinity_value) }.should.raise(Math::DomainError)
   end
 
   it "returns [Infinity, 1] when passed Infinity" do
     Math.lgamma(infinity_value).should == [infinity_value, 1]
   end
 
-  it "returns [NaN, 1] when passed NaN" do
-    Math.lgamma(nan_value)[0].nan?.should be_true
-    Math.lgamma(nan_value)[1].should == 1
+  it "returns [NaN, ...] when passed NaN" do
+    Math.lgamma(nan_value)[0].should.nan?
   end
 end
diff --git a/spec/ruby/core/math/log10_spec.rb b/spec/ruby/core/math/log10_spec.rb
index c4daedcd5c..7576a67002 100644
--- a/spec/ruby/core/math/log10_spec.rb
+++ b/spec/ruby/core/math/log10_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # The common logarithm, having base 10
 describe "Math.log10" do
   it "returns a float" do
-    Math.log10(1).should be_kind_of(Float)
+    Math.log10(1).should.is_a?(Float)
   end
 
   it "returns the base-10 logarithm of the argument" do
@@ -16,19 +16,23 @@ describe "Math.log10" do
   end
 
   it "raises an Math::DomainError if the argument is less than 0" do
-    -> { Math.log10(-1e-15) }.should raise_error(Math::DomainError)
+    -> { Math.log10(-1e-15) }.should.raise(Math::DomainError)
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.log10("test") }.should raise_error(TypeError)
+    -> { Math.log10("test") }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if passed a numerical argument as a string" do
+    -> { Math.log10("1.0") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.log10(nan_value).nan?.should be_true
+    Math.log10(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.log10(nil) }.should raise_error(TypeError)
+    -> { Math.log10(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/log1p_spec.rb b/spec/ruby/core/math/log1p_spec.rb
new file mode 100644
index 0000000000..181b462ded
--- /dev/null
+++ b/spec/ruby/core/math/log1p_spec.rb
@@ -0,0 +1,49 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "4.0" do
+  describe "Math.log1p" do
+    it "calculates Math.log(1 + arg)" do
+      Math.log1p(3).should == Math.log(1 + 3)
+    end
+
+    it "preserves precision that can be lost otherwise" do
+      Math.log1p(1e-16).should be_close(1.0e-16, TOLERANCE)
+      Math.log1p(1e-16).should != 0.0
+    end
+
+    it "raises an Math::DomainError if the argument is less than 1" do
+      -> { Math.log1p(-1-1e-15) }.should.raise(Math::DomainError, "Numerical argument is out of domain - log1p")
+    end
+
+    it "raises a TypeError if the argument cannot be coerced with Float()" do
+      -> { Math.log1p("test") }.should.raise(TypeError, "can't convert String into Float")
+    end
+
+    it "raises a TypeError for numerical values passed as string" do
+      -> { Math.log1p("10") }.should.raise(TypeError, "can't convert String into Float")
+    end
+
+    it "does not accept a second argument for the base" do
+      -> { Math.log1p(9, 3) }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 1)")
+    end
+
+    it "returns NaN given NaN" do
+      Math.log1p(nan_value).nan?.should == true
+    end
+
+    it "raises a TypeError if the argument is nil" do
+      -> { Math.log1p(nil) }.should.raise(TypeError, "can't convert nil into Float")
+    end
+
+    it "accepts any argument that can be coerced with Float()" do
+      Math.log1p(MathSpecs::Float.new).should be_close(0.6931471805599453, TOLERANCE)
+    end
+  end
+
+  describe "Math#log1p" do
+    it "is accessible as a private instance method" do
+      IncludesMath.new.send(:log1p, 4.21).should be_close(1.65057985576528, TOLERANCE)
+    end
+  end
+end
diff --git a/spec/ruby/core/math/log2_spec.rb b/spec/ruby/core/math/log2_spec.rb
index 1594f2d7af..e38a8bb67f 100644
--- a/spec/ruby/core/math/log2_spec.rb
+++ b/spec/ruby/core/math/log2_spec.rb
@@ -15,24 +15,24 @@ describe "Math.log2" do
     Math.log2((2**301+45677544234809571)).should == 301.0
   end
 
-  it "raises an Errno::EDOM if the argument is less than 0" do
-    -> { Math.log2(-1e-15) }.should raise_error( Math::DomainError)
+  it "raises Math::DomainError if the argument is less than 0" do
+    -> { Math.log2(-1e-15) }.should.raise( Math::DomainError)
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.log2("test") }.should raise_error(TypeError)
+    -> { Math.log2("test") }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed a numerical argument as a string" do
-    -> { Math.log2("1.0") }.should raise_error(TypeError)
+    -> { Math.log2("1.0") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.log2(nan_value).nan?.should be_true
+    Math.log2(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.log2(nil) }.should raise_error(TypeError)
+    -> { Math.log2(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/log_spec.rb b/spec/ruby/core/math/log_spec.rb
index 6c5036ba81..7e0bc13bc6 100644
--- a/spec/ruby/core/math/log_spec.rb
+++ b/spec/ruby/core/math/log_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # The natural logarithm, having base Math::E
 describe "Math.log" do
   it "returns a float" do
-    Math.log(1).should be_kind_of(Float)
+    Math.log(1).should.is_a?(Float)
   end
 
   it "returns the natural logarithm of the argument" do
@@ -16,15 +16,15 @@ describe "Math.log" do
   end
 
   it "raises an Math::DomainError if the argument is less than 0" do
-    -> { Math.log(-1e-15) }.should raise_error(Math::DomainError)
+    -> { Math.log(-1e-15) }.should.raise(Math::DomainError)
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.log("test") }.should raise_error(TypeError)
+    -> { Math.log("test") }.should.raise(TypeError)
   end
 
   it "raises a TypeError for numerical values passed as string" do
-    -> { Math.log("10") }.should raise_error(TypeError)
+    -> { Math.log("10") }.should.raise(TypeError)
   end
 
   it "accepts a second argument for the base" do
@@ -33,16 +33,16 @@ describe "Math.log" do
   end
 
   it "raises a TypeError when the numerical base cannot be coerced to a float" do
-    -> { Math.log(10, "2") }.should raise_error(TypeError)
-    -> { Math.log(10, nil) }.should raise_error(TypeError)
+    -> { Math.log(10, "2") }.should.raise(TypeError)
+    -> { Math.log(10, nil) }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.log(nan_value).nan?.should be_true
+    Math.log(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.log(nil) }.should raise_error(TypeError)
+    -> { Math.log(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/shared/atanh.rb b/spec/ruby/core/math/shared/atanh.rb
new file mode 100644
index 0000000000..48a6bf836e
--- /dev/null
+++ b/spec/ruby/core/math/shared/atanh.rb
@@ -0,0 +1,44 @@
+describe :math_atanh_base, shared: true do
+  it "returns a float" do
+    @object.send(@method, 0.5).should.instance_of?(Float)
+  end
+
+  it "returns the inverse hyperbolic tangent of the argument" do
+    @object.send(@method, 0.0).should == 0.0
+    @object.send(@method, -0.0).should == -0.0
+    @object.send(@method, 0.5).should be_close(0.549306144334055, TOLERANCE)
+    @object.send(@method, -0.2).should be_close(-0.202732554054082, TOLERANCE)
+  end
+
+  it "raises a TypeError if the argument is nil" do
+    -> { @object.send(@method, nil) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if the argument is not a Numeric" do
+    -> { @object.send(@method, "test") }.should.raise(TypeError)
+  end
+
+  it "returns Infinity if x == 1.0" do
+    @object.send(@method, 1.0).should == Float::INFINITY
+  end
+
+  it "return -Infinity if x == -1.0" do
+    @object.send(@method, -1.0).should == -Float::INFINITY
+  end
+end
+
+describe :math_atanh_private, shared: true do
+  it "is a private instance method" do
+    Math.private_instance_methods(false).should.include?(@method)
+  end
+end
+
+describe :math_atanh_no_complex, shared: true do
+  it "raises a Math::DomainError for arguments greater than 1.0" do
+    -> { @object.send(@method, 1.0 + Float::EPSILON)  }.should.raise(Math::DomainError)
+  end
+
+  it "raises a Math::DomainError for arguments less than -1.0" do
+    -> { @object.send(@method, -1.0 - Float::EPSILON) }.should.raise(Math::DomainError)
+  end
+end
diff --git a/spec/ruby/core/math/sin_spec.rb b/spec/ruby/core/math/sin_spec.rb
index 8e944bc95f..a9479e3aec 100644
--- a/spec/ruby/core/math/sin_spec.rb
+++ b/spec/ruby/core/math/sin_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 # sine : (-Inf, Inf) --> (-1.0, 1.0)
 describe "Math.sin" do
   it "returns a float" do
-    Math.sin(Math::PI).should be_kind_of(Float)
+    Math.sin(Math::PI).should.is_a?(Float)
   end
 
   it "returns the sine of the argument expressed in radians" do
@@ -16,15 +16,15 @@ describe "Math.sin" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.sin("test") }.should raise_error(TypeError)
+    -> { Math.sin("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.sin(nan_value).nan?.should be_true
+    Math.sin(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.sin(nil) }.should raise_error(TypeError)
+    -> { Math.sin(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/sinh_spec.rb b/spec/ruby/core/math/sinh_spec.rb
index 027c2395a7..de0f06affa 100644
--- a/spec/ruby/core/math/sinh_spec.rb
+++ b/spec/ruby/core/math/sinh_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.sinh" do
   it "returns a float" do
-    Math.sinh(1.2).should be_kind_of(Float)
+    Math.sinh(1.2).should.is_a?(Float)
   end
 
   it "returns the hyperbolic sin of the argument" do
@@ -14,15 +14,15 @@ describe "Math.sinh" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.sinh("test") }.should raise_error(TypeError)
+    -> { Math.sinh("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.sinh(nan_value).nan?.should be_true
+    Math.sinh(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.sinh(nil) }.should raise_error(TypeError)
+    -> { Math.sinh(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/sqrt_spec.rb b/spec/ruby/core/math/sqrt_spec.rb
index 779aea2a0a..545fa4d1c2 100644
--- a/spec/ruby/core/math/sqrt_spec.rb
+++ b/spec/ruby/core/math/sqrt_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.sqrt" do
   it "returns a float" do
-    Math.sqrt(1).should be_kind_of(Float)
+    Math.sqrt(1).should.is_a?(Float)
   end
 
   it "returns the square root of the argument" do
@@ -13,20 +13,24 @@ describe "Math.sqrt" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.sqrt("test") }.should raise_error(TypeError)
+    -> { Math.sqrt("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.sqrt(nan_value).nan?.should be_true
+    Math.sqrt(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.sqrt(nil) }.should raise_error(TypeError)
+    -> { Math.sqrt(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
     Math.sqrt(MathSpecs::Float.new).should be_close(1.0, TOLERANCE)
   end
+
+  it "raises a Math::DomainError when given a negative number" do
+    -> { Math.sqrt(-1) }.should.raise(Math::DomainError)
+  end
 end
 
 describe "Math#sqrt" do
diff --git a/spec/ruby/core/math/tan_spec.rb b/spec/ruby/core/math/tan_spec.rb
index c7b188cd81..c3e773f318 100644
--- a/spec/ruby/core/math/tan_spec.rb
+++ b/spec/ruby/core/math/tan_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.tan" do
   it "returns a float" do
-    Math.tan(1.35).should be_kind_of(Float)
+    Math.tan(1.35).should.is_a?(Float)
   end
 
   it "returns the tangent of the argument" do
@@ -14,20 +14,20 @@ describe "Math.tan" do
   end
 
   it "returns NaN if called with +-Infinity" do
-    Math.tan(infinity_value).nan?.should == true
-    Math.tan(-infinity_value).nan?.should == true
+    Math.tan(infinity_value).should.nan?
+    Math.tan(-infinity_value).should.nan?
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.tan("test") }.should raise_error(TypeError)
+    -> { Math.tan("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.tan(nan_value).nan?.should be_true
+    Math.tan(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.tan(nil) }.should raise_error(TypeError)
+    -> { Math.tan(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/math/tanh_spec.rb b/spec/ruby/core/math/tanh_spec.rb
index 568f8dfa77..74a938ffd8 100644
--- a/spec/ruby/core/math/tanh_spec.rb
+++ b/spec/ruby/core/math/tanh_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Math.tanh" do
   it "returns a float" do
-    Math.tanh(0.5).should be_kind_of(Float)
+    Math.tanh(0.5).should.is_a?(Float)
   end
 
   it "returns the hyperbolic tangent of the argument" do
@@ -16,15 +16,15 @@ describe "Math.tanh" do
   end
 
   it "raises a TypeError if the argument cannot be coerced with Float()" do
-    -> { Math.tanh("test") }.should raise_error(TypeError)
+    -> { Math.tanh("test") }.should.raise(TypeError)
   end
 
   it "returns NaN given NaN" do
-    Math.tanh(nan_value).nan?.should be_true
+    Math.tanh(nan_value).nan?.should == true
   end
 
   it "raises a TypeError if the argument is nil" do
-    -> { Math.tanh(nil) }.should raise_error(TypeError)
+    -> { Math.tanh(nil) }.should.raise(TypeError)
   end
 
   it "accepts any argument that can be coerced with Float()" do
diff --git a/spec/ruby/core/method/case_compare_spec.rb b/spec/ruby/core/method/case_compare_spec.rb
index 17785b5c1d..a78953e8ad 100644
--- a/spec/ruby/core/method/case_compare_spec.rb
+++ b/spec/ruby/core/method/case_compare_spec.rb
@@ -2,8 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/call'
 
-ruby_version_is "2.5" do
-  describe "Method#===" do
-    it_behaves_like :method_call, :===
-  end
+describe "Method#===" do
+  it_behaves_like :method_call, :===
 end
diff --git a/spec/ruby/core/method/clone_spec.rb b/spec/ruby/core/method/clone_spec.rb
index 3fe4000fb7..b0eb5751a9 100644
--- a/spec/ruby/core/method/clone_spec.rb
+++ b/spec/ruby/core/method/clone_spec.rb
@@ -1,14 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
+require_relative 'shared/dup'
 
 describe "Method#clone" do
-  it "returns a copy of the method" do
-    m1 = MethodSpecs::Methods.new.method(:foo)
-    m2 = m1.clone
+  it_behaves_like :method_dup, :clone
 
-    m1.should == m2
-    m1.should_not equal(m2)
-
-    m1.call.should == m2.call
+  it "preserves frozen status" do
+    method = Object.new.method(:method)
+    method.freeze
+    method.frozen?.should == true
+    method.clone.frozen?.should == true
   end
 end
diff --git a/spec/ruby/core/method/compose_spec.rb b/spec/ruby/core/method/compose_spec.rb
index aa0aded775..7506e33ea8 100644
--- a/spec/ruby/core/method/compose_spec.rb
+++ b/spec/ruby/core/method/compose_spec.rb
@@ -2,100 +2,98 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative '../proc/shared/compose'
 
-ruby_version_is "2.6" do
-  describe "Method#<<" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      succ = MethodSpecs::Composition.new.method(:succ)
-      upcase = proc { |s| s.upcase }
+describe "Method#<<" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    succ = MethodSpecs::Composition.new.method(:succ)
+    upcase = proc { |s| s.upcase }
 
-      (succ << upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ << upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      pow_2_proc = proc { |x| x * x }
-      double_proc = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    pow_2_proc = proc { |x| x * x }
+    double_proc = proc { |x| x + x }
 
-      pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
-      double_method = MethodSpecs::Composition.new.method(:double)
+    pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
+    double_method = MethodSpecs::Composition.new.method(:double)
 
-      (pow_2_method << double_proc).call(2).should == 16
-      (double_method << pow_2_proc).call(2).should == 8
-    end
+    (pow_2_method << double_proc).call(2).should == 16
+    (double_method << pow_2_proc).call(2).should == 8
+  end
 
-    it "accepts any callable object" do
-      inc = MethodSpecs::Composition.new.method(:inc)
+  it "accepts any callable object" do
+    inc = MethodSpecs::Composition.new.method(:inc)
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc << double).call(3).should == 7
-    end
+    (inc << double).call(3).should == 7
+  end
 
-    it_behaves_like :proc_compose, :<<, -> { MethodSpecs::Composition.new.method(:upcase) }
+  it_behaves_like :proc_compose, :<<, -> { MethodSpecs::Composition.new.method(:upcase) }
 
-    describe "composition" do
-      it "is a lambda" do
-        pow_2 = MethodSpecs::Composition.new.method(:pow_2)
-        double = proc { |x| x + x }
+  describe "composition" do
+    it "is a lambda" do
+      pow_2 = MethodSpecs::Composition.new.method(:pow_2)
+      double = proc { |x| x + x }
 
-        (pow_2 << double).is_a?(Proc).should == true
-        (pow_2 << double).lambda?.should == true
-      end
+      (pow_2 << double).is_a?(Proc).should == true
+      (pow_2 << double).should_not.lambda?
+    end
 
-      it "may accept multiple arguments" do
-        inc = MethodSpecs::Composition.new.method(:inc)
-        mul = proc { |n, m| n * m }
+    it "may accept multiple arguments" do
+      inc = MethodSpecs::Composition.new.method(:inc)
+      mul = proc { |n, m| n * m }
 
-        (inc << mul).call(2, 3).should == 7
-      end
+      (inc << mul).call(2, 3).should == 7
     end
   end
+end
 
-  describe "Method#>>" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = MethodSpecs::Composition.new.method(:succ)
+describe "Method#>>" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = MethodSpecs::Composition.new.method(:succ)
 
-      (succ >> upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ >> upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      pow_2_proc = proc { |x| x * x }
-      double_proc = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    pow_2_proc = proc { |x| x * x }
+    double_proc = proc { |x| x + x }
 
-      pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
-      double_method = MethodSpecs::Composition.new.method(:double)
+    pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
+    double_method = MethodSpecs::Composition.new.method(:double)
 
-      (pow_2_method >> double_proc).call(2).should == 8
-      (double_method >> pow_2_proc).call(2).should == 16
-    end
+    (pow_2_method >> double_proc).call(2).should == 8
+    (double_method >> pow_2_proc).call(2).should == 16
+  end
 
-    it "accepts any callable object" do
-      inc = MethodSpecs::Composition.new.method(:inc)
+  it "accepts any callable object" do
+    inc = MethodSpecs::Composition.new.method(:inc)
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc >> double).call(3).should == 8
-    end
+    (inc >> double).call(3).should == 8
+  end
 
-    it_behaves_like :proc_compose, :>>, -> { MethodSpecs::Composition.new.method(:upcase) }
+  it_behaves_like :proc_compose, :>>, -> { MethodSpecs::Composition.new.method(:upcase) }
 
-    describe "composition" do
-      it "is a lambda" do
-        pow_2 = MethodSpecs::Composition.new.method(:pow_2)
-        double = proc { |x| x + x }
+  describe "composition" do
+    it "is a lambda" do
+      pow_2 = MethodSpecs::Composition.new.method(:pow_2)
+      double = proc { |x| x + x }
 
-        (pow_2 >> double).is_a?(Proc).should == true
-        (pow_2 >> double).lambda?.should == true
-      end
+      (pow_2 >> double).is_a?(Proc).should == true
+      (pow_2 >> double).should.lambda?
+    end
 
-      it "may accept multiple arguments" do
-        mul = MethodSpecs::Composition.new.method(:mul)
-        inc = proc { |n| n + 1 }
+    it "may accept multiple arguments" do
+      mul = MethodSpecs::Composition.new.method(:mul)
+      inc = proc { |n| n + 1 }
 
-        (mul >> inc).call(2, 3).should == 7
-      end
+      (mul >> inc).call(2, 3).should == 7
     end
   end
 end
diff --git a/spec/ruby/core/method/curry_spec.rb b/spec/ruby/core/method/curry_spec.rb
index 219de0f6b5..79c5d7c662 100644
--- a/spec/ruby/core/method/curry_spec.rb
+++ b/spec/ruby/core/method/curry_spec.rb
@@ -7,7 +7,7 @@ describe "Method#curry" do
     def x.foo(a,b,c); [a,b,c]; end
 
     c = x.method(:foo).curry
-    c.should be_kind_of(Proc)
+    c.should.is_a?(Proc)
     c.call(1).call(2, 3).should == [1,2,3]
   end
 
@@ -17,20 +17,20 @@ describe "Method#curry" do
     end
 
     it "returns a curried proc when given correct arity" do
-      @obj.method(:one_req).curry(1).should be_kind_of(Proc)
-      @obj.method(:zero_with_splat).curry(100).should be_kind_of(Proc)
-      @obj.method(:two_req_with_splat).curry(2).should be_kind_of(Proc)
+      @obj.method(:one_req).curry(1).should.is_a?(Proc)
+      @obj.method(:zero_with_splat).curry(100).should.is_a?(Proc)
+      @obj.method(:two_req_with_splat).curry(2).should.is_a?(Proc)
     end
 
     it "raises ArgumentError when the method requires less arguments than the given arity" do
-      -> { @obj.method(:zero).curry(1) }.should raise_error(ArgumentError)
-      -> { @obj.method(:one_req_one_opt).curry(3) }.should raise_error(ArgumentError)
-      -> { @obj.method(:two_req_one_opt_with_block).curry(4) }.should raise_error(ArgumentError)
+      -> { @obj.method(:zero).curry(1) }.should.raise(ArgumentError)
+      -> { @obj.method(:one_req_one_opt).curry(3) }.should.raise(ArgumentError)
+      -> { @obj.method(:two_req_one_opt_with_block).curry(4) }.should.raise(ArgumentError)
     end
 
     it "raises ArgumentError when the method requires more arguments than the given arity" do
-      -> { @obj.method(:two_req_with_splat).curry(1) }.should raise_error(ArgumentError)
-      -> { @obj.method(:one_req).curry(0) }.should raise_error(ArgumentError)
+      -> { @obj.method(:two_req_with_splat).curry(1) }.should.raise(ArgumentError)
+      -> { @obj.method(:one_req).curry(0) }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/method/dup_spec.rb b/spec/ruby/core/method/dup_spec.rb
new file mode 100644
index 0000000000..e3e29d8a68
--- /dev/null
+++ b/spec/ruby/core/method/dup_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+require_relative 'shared/dup'
+
+describe "Method#dup" do
+  ruby_version_is "3.4" do
+    it_behaves_like :method_dup, :dup
+
+    it "resets frozen status" do
+      method = Object.new.method(:method)
+      method.freeze
+      method.frozen?.should == true
+      method.dup.frozen?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/method/fixtures/classes.rb b/spec/ruby/core/method/fixtures/classes.rb
index f3b7ff921c..41904df1d1 100644
--- a/spec/ruby/core/method/fixtures/classes.rb
+++ b/spec/ruby/core/method/fixtures/classes.rb
@@ -27,6 +27,7 @@ module MethodSpecs
 
     alias bar foo
     alias baz bar
+    alias qux baz
 
     def same_as_foo
       true
@@ -50,6 +51,8 @@ module MethodSpecs
     def one_req(a); end
     def two_req(a, b); end
 
+    def one_req_named(a:); end
+
     def zero_with_block(&blk); end
     def one_req_with_block(a, &blk); end
     def two_req_with_block(a, b, &blk); end
@@ -59,6 +62,8 @@ module MethodSpecs
     def one_req_two_opt(a, b=nil, c=nil); end
     def two_req_one_opt(a, b, c=nil); end
 
+    def one_opt_named(a: nil); end
+
     def one_opt_with_block(a=nil, &blk); end
     def one_req_one_opt_with_block(a, b=nil, &blk); end
     def one_req_two_opt_with_block(a, b=nil, c=nil, &blk); end
@@ -71,6 +76,8 @@ module MethodSpecs
     def two_req_one_opt_with_splat(a, b, c=nil, *d); end
     def one_req_two_opt_with_splat(a, b=nil, c=nil, *d); end
 
+    def zero_with_double_splat(**a); end
+
     def zero_with_splat_and_block(*a, &blk); end
     def one_req_with_splat_and_block(a, *b, &blk); end
     def two_req_with_splat_and_block(a, b, *c, &blk); end
@@ -78,6 +85,12 @@ module MethodSpecs
     def two_req_one_opt_with_splat_and_block(a, b, c=nil, *d, &blk); end
     def one_req_two_opt_with_splat_and_block(a, b=nil, c=nil, *d, &blk); end
 
+    def my_public_method; end
+    def my_protected_method; end
+    def my_private_method; end
+    protected :my_protected_method
+    private :my_private_method
+
     define_method(:zero_defined_method, Proc.new {||})
     define_method(:zero_with_splat_defined_method, Proc.new {|*x|})
     define_method(:one_req_defined_method, Proc.new {|x|})
@@ -207,4 +220,28 @@ module MethodSpecs
       n * m
     end
   end
+
+  module InheritedMethods
+    module A
+      private
+      def derp(message)
+        'A'
+      end
+    end
+
+    module B
+      private
+      def derp
+        'B' + super('superclass')
+      end
+    end
+
+    class C
+      include A
+      include B
+
+      public :derp
+      alias_method :meow, :derp
+    end
+  end
 end
diff --git a/spec/ruby/core/method/inspect_spec.rb b/spec/ruby/core/method/inspect_spec.rb
index e0fe1afdd0..97ff2d8c11 100644
--- a/spec/ruby/core/method/inspect_spec.rb
+++ b/spec/ruby/core/method/inspect_spec.rb
@@ -1,6 +1,8 @@
 require_relative '../../spec_helper'
 require_relative 'shared/to_s'
+require_relative 'shared/aliased_inspect'
 
 describe "Method#inspect" do
   it_behaves_like :method_to_s, :inspect
+  it_behaves_like :method_to_s_aliased, :inspect, -> meth { meth }
 end
diff --git a/spec/ruby/core/method/original_name_spec.rb b/spec/ruby/core/method/original_name_spec.rb
index 676fdaedb4..b92cf35154 100644
--- a/spec/ruby/core/method/original_name_spec.rb
+++ b/spec/ruby/core/method/original_name_spec.rb
@@ -19,4 +19,41 @@ describe "Method#original_name" do
     obj.method(:baz).original_name.should == :foo
     obj.method(:baz).unbind.bind(obj).original_name.should == :foo
   end
+
+  it "returns the original name even when aliased thrice" do
+    obj = MethodSpecs::Methods.new
+    obj.method(:qux).original_name.should == :foo
+    obj.method(:qux).unbind.bind(obj).original_name.should == :foo
+  end
+
+  it "returns the source UnboundMethod's name (not the name given to define_method)" do
+    klass = Class.new { define_method(:my_inspect, ::Kernel.instance_method(:inspect)) }
+    klass.new.method(:my_inspect).original_name.should == :inspect
+  end
+
+  it "preserves the source method's name through define_method and alias" do
+    source = Class.new { def my_method; end }
+    klass = Class.new(source) do
+      define_method(:renamed, source.instance_method(:my_method))
+      alias aliased renamed
+    end
+    klass.new.method(:renamed).original_name.should == :my_method
+    klass.new.method(:aliased).original_name.should == :my_method
+  end
+
+  it "returns the source UnboundMethod's name for Kernel#is_a? and Kernel#kind_of?" do
+    klass = Class.new { define_method(:my_is_a?, ::Kernel.instance_method(:is_a?)) }
+    klass.new.method(:my_is_a?).original_name.should == :is_a?
+
+    klass = Class.new { define_method(:my_kind_of?, ::Kernel.instance_method(:kind_of?)) }
+    klass.new.method(:my_kind_of?).original_name.should == :kind_of?
+  end
+
+  it "preserves the source name when aliasing a define_method'd Kernel method" do
+    klass = Class.new do
+      define_method(:my_is_a?, ::Kernel.instance_method(:is_a?))
+      alias_method :renamed_is_a?, :my_is_a?
+    end
+    klass.new.method(:renamed_is_a?).original_name.should == :is_a?
+  end
 end
diff --git a/spec/ruby/core/method/owner_spec.rb b/spec/ruby/core/method/owner_spec.rb
index ca5dff7295..1cdc4edfa7 100644
--- a/spec/ruby/core/method/owner_spec.rb
+++ b/spec/ruby/core/method/owner_spec.rb
@@ -23,4 +23,8 @@ describe "Method#owner" do
       @m.method(:handled_via_method_missing).owner.should == MethodSpecs::Methods
     end
   end
+
+  it "returns the class on which public was called for a private method in ancestor" do
+    MethodSpecs::InheritedMethods::C.new.method(:derp).owner.should == MethodSpecs::InheritedMethods::C
+  end
 end
diff --git a/spec/ruby/core/method/parameters_spec.rb b/spec/ruby/core/method/parameters_spec.rb
index 3fdaf9ce6f..fd88e8dcb8 100644
--- a/spec/ruby/core/method/parameters_spec.rb
+++ b/spec/ruby/core/method/parameters_spec.rb
@@ -7,6 +7,7 @@ describe "Method#parameters" do
     def one_keyrest(**a); end
 
     def one_keyreq(a:); end
+    def one_nokey(**nil); end
 
     def one_splat_one_req(*a,b); end
     def one_splat_two_req(*a,b,c); end
@@ -15,11 +16,22 @@ describe "Method#parameters" do
     def one_opt_with_stabby(a=-> b { true }); end
 
     def one_unnamed_splat(*); end
+    def one_unnamed_keyrest(**); end
 
     def one_splat_one_block(*args, &block)
       local_is_not_parameter = {}
     end
 
+    ruby_version_is "4.1" do
+      eval <<-RUBY
+        def one_noblock(&nil); end
+      RUBY
+    end
+
+    def forward_parameters(...) end
+
+    def underscore_parameters(_, _, _ = 1, *_, _:, _: 2, **_, &_); end
+
     define_method(:one_optional_defined_method) {|x = 1|}
   end
 
@@ -176,6 +188,18 @@ describe "Method#parameters" do
     m.parameters.should == [[:keyreq,:a]]
   end
 
+  it "returns [[:nokey]] for a method with a single **nil parameter" do
+    m = MethodSpecs::Methods.instance_method(:one_nokey)
+    m.parameters.should == [[:nokey]]
+  end
+
+  ruby_version_is "4.1" do
+    it "returns [[:noblock]] for a method with a single &nil parameter" do
+      m = MethodSpecs::Methods.instance_method(:one_noblock)
+      m.parameters.should == [[:noblock]]
+    end
+  end
+
   it "works with ->(){} as the value of an optional argument" do
     m = MethodSpecs::Methods.instance_method(:one_opt_with_stabby)
     m.parameters.should == [[:opt,:a]]
@@ -222,9 +246,27 @@ describe "Method#parameters" do
     m.method(:handled_via_method_missing).parameters.should == [[:rest]]
   end
 
-  it "adds nameless rest arg for \"star\" argument" do
+  it "adds rest arg with name * for \"star\" argument" do
     m = MethodSpecs::Methods.new
-    m.method(:one_unnamed_splat).parameters.should == [[:rest]]
+    m.method(:one_unnamed_splat).parameters.should == [[:rest, :*]]
+  end
+
+  it "adds keyrest arg with ** as a name for \"double star\" argument" do
+    m = MethodSpecs::Methods.new
+    m.method(:one_unnamed_keyrest).parameters.should == [[:keyrest, :**]]
+  end
+
+  it "adds block arg with name & for anonymous block argument" do
+    object = Object.new
+    def object.foo(&)
+    end
+
+    object.method(:foo).parameters.should == [[:block, :&]]
+  end
+
+  it "returns [:rest, :*], [:keyrest, :**], [:block, :&] for forward parameters operator" do
+    m = MethodSpecs::Methods.new
+    m.method(:forward_parameters).parameters.should == [[:rest, :*], [:keyrest, :**], [:block, :&]]
   end
 
   it "returns the args and block for a splat and block argument" do
@@ -242,6 +284,20 @@ describe "Method#parameters" do
     m.method(:writer=).parameters.should == [[:req]]
   end
 
+  it "returns all parameters defined with the name _ as _" do
+    m = MethodSpecs::Methods.instance_method(:underscore_parameters)
+    m.parameters.should == [
+      [:req, :_],
+      [:req, :_],
+      [:opt, :_],
+      [:rest, :_],
+      [:keyreq, :_],
+      [:key, :_],
+      [:keyrest, :_],
+      [:block, :_]
+    ]
+  end
+
   it "returns [[:rest]] for core methods with variable-length argument lists" do
     # delete! takes rest args
     "foo".method(:delete!).parameters.should == [[:rest]]
@@ -252,7 +308,7 @@ describe "Method#parameters" do
     [
       [[:rest]],
       [[:opt]]
-    ].should include([].method(:pop).parameters)
+    ].should.include?([].method(:pop).parameters)
   end
 
   it "returns [[:req]] for each parameter for core methods with fixed-length argument lists" do
diff --git a/spec/ruby/core/method/private_spec.rb b/spec/ruby/core/method/private_spec.rb
new file mode 100644
index 0000000000..e708542b2e
--- /dev/null
+++ b/spec/ruby/core/method/private_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Method#private?" do
+  it "has been removed" do
+    obj = MethodSpecs::Methods.new
+    obj.method(:my_private_method).should_not.respond_to?(:private?)
+  end
+end
diff --git a/spec/ruby/core/method/protected_spec.rb b/spec/ruby/core/method/protected_spec.rb
new file mode 100644
index 0000000000..f9e422ae3d
--- /dev/null
+++ b/spec/ruby/core/method/protected_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Method#protected?" do
+  it "has been removed" do
+    obj = MethodSpecs::Methods.new
+    obj.method(:my_protected_method).should_not.respond_to?(:protected?)
+  end
+end
diff --git a/spec/ruby/core/method/public_spec.rb b/spec/ruby/core/method/public_spec.rb
new file mode 100644
index 0000000000..4cb23f4cf1
--- /dev/null
+++ b/spec/ruby/core/method/public_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Method#public?" do
+  it "has been removed" do
+    obj = MethodSpecs::Methods.new
+    obj.method(:my_public_method).should_not.respond_to?(:public?)
+  end
+end
diff --git a/spec/ruby/core/method/receiver_spec.rb b/spec/ruby/core/method/receiver_spec.rb
index 2b2e11dd2e..315a08d288 100644
--- a/spec/ruby/core/method/receiver_spec.rb
+++ b/spec/ruby/core/method/receiver_spec.rb
@@ -4,19 +4,19 @@ require_relative 'fixtures/classes'
 describe "Method#receiver" do
   it "returns the receiver of the method" do
     s = "abc"
-    s.method(:upcase).receiver.should equal(s)
+    s.method(:upcase).receiver.should.equal?(s)
   end
 
   it "returns the right receiver even when aliased" do
     obj = MethodSpecs::Methods.new
-    obj.method(:foo).receiver.should equal(obj)
-    obj.method(:bar).receiver.should equal(obj)
+    obj.method(:foo).receiver.should.equal?(obj)
+    obj.method(:bar).receiver.should.equal?(obj)
   end
 
   describe "for a Method generated by respond_to_missing?" do
     it "returns the receiver of the method" do
       m = MethodSpecs::Methods.new
-      m.method(:handled_via_method_missing).receiver.should equal(m)
+      m.method(:handled_via_method_missing).receiver.should.equal?(m)
     end
   end
 end
diff --git a/spec/ruby/core/method/shared/aliased_inspect.rb b/spec/ruby/core/method/shared/aliased_inspect.rb
new file mode 100644
index 0000000000..2a622c2f97
--- /dev/null
+++ b/spec/ruby/core/method/shared/aliased_inspect.rb
@@ -0,0 +1,31 @@
+describe :method_to_s_aliased, shared: true do
+  # @object converts a bound Method to either a Method (identity) or an
+  # UnboundMethod (-> meth { meth.unbind }), so these expectations cover both
+  # Method#to_s/#inspect and UnboundMethod#to_s/#inspect.
+
+  it "shows the original name in parentheses for an aliased method" do
+    klass = Class.new do
+      def original_method; end
+      alias_method :renamed_method, :original_method
+    end
+    @object.call(klass.new.method(:renamed_method)).send(@method).should.include? '#renamed_method(original_method)'
+  end
+
+  it "shows the source UnboundMethod's name in parentheses for a define_method'd method" do
+    klass = Class.new { define_method(:renamed_is_a?, ::Kernel.instance_method(:is_a?)) }
+    @object.call(klass.new.method(:renamed_is_a?)).send(@method).should.include? '#renamed_is_a?(is_a?)'
+  end
+
+  it "does not annotate a directly looked-up Kernel method with a shared internal name" do
+    @object.call(Object.new.method(:is_a?)).send(@method).should_not.include? '(kind_of?)'
+    @object.call(Object.new.method(:kind_of?)).send(@method).should_not.include? '(is_a?)'
+  end
+
+  it "shows the source name when aliasing a define_method'd Kernel method" do
+    klass = Class.new do
+      define_method(:my_is_a?, ::Kernel.instance_method(:is_a?))
+      alias_method :renamed_is_a?, :my_is_a?
+    end
+    @object.call(klass.new.method(:renamed_is_a?)).send(@method).should.include? '#renamed_is_a?(is_a?)'
+  end
+end
diff --git a/spec/ruby/core/method/shared/call.rb b/spec/ruby/core/method/shared/call.rb
index f26e373695..41ee2b06cb 100644
--- a/spec/ruby/core/method/shared/call.rb
+++ b/spec/ruby/core/method/shared/call.rb
@@ -11,10 +11,10 @@ describe :method_call, shared: true do
   it "raises an ArgumentError when given incorrect number of arguments" do
     -> {
       MethodSpecs::Methods.new.method(:two_req).send(@method, 1, 2, 3)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       MethodSpecs::Methods.new.method(:two_req).send(@method, 1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   describe "for a Method generated by respond_to_missing?" do
diff --git a/spec/ruby/core/method/shared/dup.rb b/spec/ruby/core/method/shared/dup.rb
new file mode 100644
index 0000000000..eee790890a
--- /dev/null
+++ b/spec/ruby/core/method/shared/dup.rb
@@ -0,0 +1,32 @@
+describe :method_dup, shared: true do
+  it "returns a copy of self" do
+    a = Object.new.method(:method)
+    b = a.send(@method)
+
+    a.should == b
+    a.should_not.equal?(b)
+  end
+
+  ruby_version_is "3.4" do
+    it "copies instance variables" do
+      method = Object.new.method(:method)
+      method.instance_variable_set(:@ivar, 1)
+      cl = method.send(@method)
+      cl.instance_variables.should == [:@ivar]
+    end
+
+    it "copies the finalizer" do
+      code = <<-'RUBY'
+        obj = Object.new.method(:method)
+
+        ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized\n" })
+
+        obj.clone
+
+        exit 0
+      RUBY
+
+      ruby_exe(code).lines.sort.should == ["finalized\n", "finalized\n"]
+    end
+  end
+end
diff --git a/spec/ruby/core/method/shared/eql.rb b/spec/ruby/core/method/shared/eql.rb
index 5c720cbac1..3c340202b7 100644
--- a/spec/ruby/core/method/shared/eql.rb
+++ b/spec/ruby/core/method/shared/eql.rb
@@ -12,54 +12,54 @@ describe :method_equal, shared: true do
   it "returns true if methods are the same" do
     m2 = @m.method(:foo)
 
-    @m_foo.send(@method, @m_foo).should be_true
-    @m_foo.send(@method, m2).should be_true
+    @m_foo.send(@method, @m_foo).should == true
+    @m_foo.send(@method, m2).should == true
   end
 
   it "returns true on aliased methods" do
     m_bar = @m.method(:bar)
 
-    m_bar.send(@method, @m_foo).should be_true
+    m_bar.send(@method, @m_foo).should == true
   end
 
   it "returns true if the two core methods are aliases" do
     s = "hello"
     a = s.method(:size)
     b = s.method(:length)
-    a.send(@method, b).should be_true
+    a.send(@method, b).should == true
   end
 
   it "returns false on a method which is neither aliased nor the same method" do
     m2 = @m.method(:zero)
 
-    @m_foo.send(@method, m2).should be_false
+    @m_foo.send(@method, m2).should == false
   end
 
   it "returns false for a method which is not bound to the same object" do
     m2_foo = @m2.method(:foo)
     a_baz = @a.method(:baz)
 
-    @m_foo.send(@method, m2_foo).should be_false
-    @m_foo.send(@method, a_baz).should be_false
+    @m_foo.send(@method, m2_foo).should == false
+    @m_foo.send(@method, a_baz).should == false
   end
 
   it "returns false if the two methods are bound to the same object but were defined independently" do
     m2 = @m.method(:same_as_foo)
-    @m_foo.send(@method, m2).should be_false
+    @m_foo.send(@method, m2).should == false
   end
 
   it "returns true if a method was defined using the other one" do
     MethodSpecs::Methods.send :define_method, :defined_foo, MethodSpecs::Methods.instance_method(:foo)
     m2 = @m.method(:defined_foo)
-    @m_foo.send(@method, m2).should be_true
+    @m_foo.send(@method, m2).should == true
   end
 
   it "returns false if comparing a method defined via define_method and def" do
     defn = @m.method(:zero)
     defined = @m.method(:zero_defined_method)
 
-    defn.send(@method, defined).should be_false
-    defined.send(@method, defn).should be_false
+    defn.send(@method, defined).should == false
+    defined.send(@method, defn).should == false
   end
 
   describe 'missing methods' do
@@ -68,8 +68,8 @@ describe :method_equal, shared: true do
       miss1bis = @m.method(:handled_via_method_missing)
       miss2 = @m.method(:also_handled)
 
-      miss1.send(@method, miss1bis).should be_true
-      miss1.send(@method, miss2).should be_false
+      miss1.send(@method, miss1bis).should == true
+      miss1.send(@method, miss2).should == false
     end
 
     it 'calls respond_to_missing? with true to include private methods' do
@@ -81,14 +81,14 @@ describe :method_equal, shared: true do
   it "returns false if the two methods are bound to different objects, have the same names, and identical bodies" do
     a = MethodSpecs::Eql.instance_method(:same_body)
     b = MethodSpecs::Eql2.instance_method(:same_body)
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
   end
 
   it "returns false if the argument is not a Method object" do
-    String.instance_method(:size).send(@method, 7).should be_false
+    String.instance_method(:size).send(@method, 7).should == false
   end
 
   it "returns false if the argument is an unbound version of self" do
-    method(:load).send(@method, method(:load).unbind).should be_false
+    method(:load).send(@method, method(:load).unbind).should == false
   end
 end
diff --git a/spec/ruby/core/method/shared/to_s.rb b/spec/ruby/core/method/shared/to_s.rb
index 373398a785..bfb58e6896 100644
--- a/spec/ruby/core/method/shared/to_s.rb
+++ b/spec/ruby/core/method/shared/to_s.rb
@@ -4,16 +4,16 @@ require_relative '../fixtures/classes'
 describe :method_to_s, shared: true do
   before :each do
     @m = MethodSpecs::MySub.new.method :bar
-    @string = @m.send(@method).sub(/0x\w+/, '0xXXXXXX')
+    @string = @m.send(@method)
   end
 
   it "returns a String" do
-    @m.send(@method).should be_kind_of(String)
+    @m.send(@method).should.is_a?(String)
   end
 
   it "returns a String for methods defined with attr_accessor" do
     m = MethodSpecs::Methods.new.method :attr
-    m.send(@method).should be_kind_of(String)
+    m.send(@method).should.is_a?(String)
   end
 
   it "returns a String containing 'Method'" do
@@ -24,6 +24,19 @@ describe :method_to_s, shared: true do
     @string.should =~ /\#bar/
   end
 
+  it "returns a String containing method arguments" do
+    obj = MethodSpecs::Methods.new
+    obj.method(:zero).send(@method).should.include?("()")
+    obj.method(:one_req).send(@method).should.include?("(a)")
+    obj.method(:one_req_named).send(@method).should.include?("(a:)")
+    obj.method(:zero_with_block).send(@method).should.include?("(&blk)")
+    obj.method(:one_opt).send(@method).should.include?("(a=...)")
+    obj.method(:one_opt_named).send(@method).should.include?("(a: ...)")
+    obj.method(:zero_with_splat).send(@method).should.include?("(*a)")
+    obj.method(:zero_with_double_splat).send(@method).should.include?("(**a)")
+    obj.method(:one_req_one_opt_with_splat_and_block).send(@method).should.include?("(a, b=..., *c, &blk)")
+  end
+
   it "returns a String containing the Module the method is defined in" do
     @string.should =~ /MethodSpecs::MyMod/
   end
@@ -31,4 +44,38 @@ describe :method_to_s, shared: true do
   it "returns a String containing the Module the method is referenced from" do
     @string.should =~ /MethodSpecs::MySub/
   end
+
+  it "returns a String including all details" do
+    @string.should.start_with? "#<Method: MethodSpecs::MySub(MethodSpecs::MyMod)#bar"
+  end
+
+  it "does not show the defining module if it is the same as the receiver class" do
+    MethodSpecs::A.new.method(:baz).send(@method).should.start_with? "#<Method: MethodSpecs::A#baz"
+  end
+
+  it "returns a String containing the Module containing the method if object has a singleton class but method is not defined in the singleton class" do
+    obj = MethodSpecs::MySub.new
+    obj.singleton_class
+    @m = obj.method(:bar)
+    @string = @m.send(@method)
+    @string.should.start_with? "#<Method: MethodSpecs::MySub(MethodSpecs::MyMod)#bar"
+
+    c = MethodSpecs::MySub.dup
+    m = Module.new{def bar; end}
+    c.extend(m)
+    @string = c.method(:bar).send(@method)
+    @string.should.start_with? "#<Method: #<Class:#{c.inspect}>(#{m.inspect})#bar"
+  end
+
+  it "returns a String containing the singleton class if method is defined in the singleton class" do
+    obj = MethodSpecs::MySub.new
+    def obj.bar; end
+    @m = obj.method(:bar)
+    @string = @m.send(@method).sub(/0x\h+/, '0xXXXXXX')
+    @string.should.start_with? "#<Method: #<MethodSpecs::MySub:0xXXXXXX>.bar"
+  end
+
+  it "shows the metaclass and the owner for a Module instance method retrieved from a class" do
+    String.method(:include).inspect.should.start_with?("#<Method: #<Class:String>(Module)#include")
+  end
 end
diff --git a/spec/ruby/core/method/source_location_spec.rb b/spec/ruby/core/method/source_location_spec.rb
index dd81b02c77..22fcb98c74 100644
--- a/spec/ruby/core/method/source_location_spec.rb
+++ b/spec/ruby/core/method/source_location_spec.rb
@@ -7,18 +7,18 @@ describe "Method#source_location" do
   end
 
   it "returns an Array" do
-    @method.source_location.should be_an_instance_of(Array)
+    @method.source_location.should.instance_of?(Array)
   end
 
   it "sets the first value to the path of the file in which the method was defined" do
     file = @method.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/classes.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
-  it "sets the last value to a Fixnum representing the line on which the method was defined" do
+  it "sets the last value to an Integer representing the line on which the method was defined" do
     line = @method.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 5
   end
 
@@ -86,10 +86,35 @@ describe "Method#source_location" do
     method.source_location[1].should == line
   end
 
+  it "works for core methods where it returns nil or <internal:" do
+    loc = method(:__id__).source_location
+    if loc == nil
+      loc.should == nil
+    else
+      loc[0].should.start_with?('<internal:')
+      loc[1].should.is_a?(Integer)
+    end
+
+    loc = method(:tap).source_location
+    if loc == nil
+      loc.should == nil
+    else
+      loc[0].should.start_with?('<internal:')
+      loc[1].should.is_a?(Integer)
+    end
+  end
+
+  it "works for eval with a given line" do
+    c = Class.new do
+      eval('def self.m; end', nil, "foo", 100)
+    end
+    c.method(:m).source_location.should == ["foo", 100]
+  end
+
   describe "for a Method generated by respond_to_missing?" do
     it "returns nil" do
       m = MethodSpecs::Methods.new
-      m.method(:handled_via_method_missing).source_location.should be_nil
+      m.method(:handled_via_method_missing).source_location.should == nil
     end
   end
 end
diff --git a/spec/ruby/core/method/super_method_spec.rb b/spec/ruby/core/method/super_method_spec.rb
index e5d8b87a06..c63a7aaa0f 100644
--- a/spec/ruby/core/method/super_method_spec.rb
+++ b/spec/ruby/core/method/super_method_spec.rb
@@ -42,4 +42,23 @@ describe "Method#super_method" do
 
     method.super_method.should == nil
   end
+
+  # https://github.com/jruby/jruby/issues/7240
+  context "after changing an inherited methods visibility" do
+    it "calls the proper super method" do
+      MethodSpecs::InheritedMethods::C.new.derp.should == 'BA'
+    end
+
+    it "returns the expected super_method" do
+      method = MethodSpecs::InheritedMethods::C.new.method(:derp)
+      method.super_method.owner.should == MethodSpecs::InheritedMethods::A
+    end
+  end
+
+  context "after aliasing an inherited method" do
+    it "returns the expected super_method" do
+      method = MethodSpecs::InheritedMethods::C.new.method(:meow)
+      method.super_method.owner.should == MethodSpecs::InheritedMethods::A
+    end
+  end
 end
diff --git a/spec/ruby/core/method/to_proc_spec.rb b/spec/ruby/core/method/to_proc_spec.rb
index 29b7bec2b3..4993cce239 100644
--- a/spec/ruby/core/method/to_proc_spec.rb
+++ b/spec/ruby/core/method/to_proc_spec.rb
@@ -35,7 +35,7 @@ describe "Method#to_proc" do
   end
 
   it "returns a proc that can be used by define_method" do
-    x = 'test'
+    x = +'test'
     to_s = class << x
       define_method :foo, method(:to_s).to_proc
       to_s
diff --git a/spec/ruby/core/method/to_s_spec.rb b/spec/ruby/core/method/to_s_spec.rb
index 9f19011302..ba0b4fa3c6 100644
--- a/spec/ruby/core/method/to_s_spec.rb
+++ b/spec/ruby/core/method/to_s_spec.rb
@@ -1,6 +1,8 @@
 require_relative '../../spec_helper'
 require_relative 'shared/to_s'
+require_relative 'shared/aliased_inspect'
 
 describe "Method#to_s" do
   it_behaves_like :method_to_s, :to_s
+  it_behaves_like :method_to_s_aliased, :to_s, -> meth { meth }
 end
diff --git a/spec/ruby/core/method/unbind_spec.rb b/spec/ruby/core/method/unbind_spec.rb
index 3d36c6d675..994c3a8879 100644
--- a/spec/ruby/core/method/unbind_spec.rb
+++ b/spec/ruby/core/method/unbind_spec.rb
@@ -11,23 +11,32 @@ describe "Method#unbind" do
   end
 
   it "returns an UnboundMethod" do
-    @normal_um.should be_kind_of(UnboundMethod)
+    @normal_um.should.is_a?(UnboundMethod)
   end
 
-  it "returns a String containing 'UnboundMethod'" do
-    @string.should =~ /\bUnboundMethod\b/
-  end
+  describe "#inspect" do
+    it "returns a String containing 'UnboundMethod'" do
+      @string.should =~ /\bUnboundMethod\b/
+    end
 
-  it "returns a String containing the method name" do
-    @string.should =~ /\#bar/
-  end
+    it "returns a String containing the method name" do
+      @string.should =~ /\#bar/
+    end
+
+    it "returns a String containing the Module the method is defined in" do
+      @string.should =~ /MethodSpecs::MyMod/
+    end
 
-  it "returns a String containing the Module the method is defined in" do
-    @string.should =~ /MethodSpecs::MyMod/
+    it "returns a String containing the Module the method is referenced from" do
+      @string.should =~ /MethodSpecs::MyMod/
+    end
   end
 
-  it "returns a String containing the Module the method is referenced from" do
-    @string.should =~ /MethodSpecs::MySub/
+  it "keeps the origin singleton class if there is one" do
+    obj = Object.new
+    def obj.foo
+    end
+    obj.method(:foo).unbind.inspect.should.start_with?("#<UnboundMethod: #{obj.singleton_class}#foo")
   end
 
   specify "rebinding UnboundMethod to Method's obj produces exactly equivalent Methods" do
diff --git a/spec/ruby/core/module/alias_method_spec.rb b/spec/ruby/core/module/alias_method_spec.rb
index b14f5430a8..852879cc8a 100644
--- a/spec/ruby/core/module/alias_method_spec.rb
+++ b/spec/ruby/core/module/alias_method_spec.rb
@@ -14,7 +14,7 @@ describe "Module#alias_method" do
     @object.double(12).should == @object.public_two(12)
   end
 
-  it "creates methods that are == to eachother" do
+  it "creates methods that are == to each other" do
     @class.make_alias :uno, :public_one
     @object.method(:uno).should == @object.method(:public_one)
   end
@@ -28,12 +28,12 @@ describe "Module#alias_method" do
 
   it "retains method visibility" do
     @class.make_alias :private_ichi, :private_one
-    -> { @object.private_one  }.should raise_error(NameError)
-    -> { @object.private_ichi }.should raise_error(NameError)
+    -> { @object.private_one  }.should.raise(NameError)
+    -> { @object.private_ichi }.should.raise(NameError)
     @class.make_alias :public_ichi, :public_one
     @object.public_ichi.should == @object.public_one
     @class.make_alias :protected_ichi, :protected_one
-    -> { @object.protected_ichi }.should raise_error(NameError)
+    -> { @object.protected_ichi }.should.raise(NameError)
   end
 
   it "handles aliasing a stub that changes visibility" do
@@ -42,16 +42,28 @@ describe "Module#alias_method" do
     @object.was_private_one.should == 1
   end
 
+  it "handles aliasing a method only present in a refinement" do
+    c = @class
+    Module.new do
+      refine c do
+        def uno_refined_method
+        end
+        alias_method :double_refined_method, :uno_refined_method
+        instance_method(:uno_refined_method).should == instance_method(:double_refined_method)
+      end
+    end
+  end
+
   it "fails if origin method not found" do
-    -> { @class.make_alias :ni, :san }.should raise_error(NameError) { |e|
+    -> { @class.make_alias :ni, :san }.should.raise(NameError) { |e|
       # a NameError and not a NoMethodError
       e.class.should == NameError
     }
   end
 
-  it "raises #{frozen_error_class} if frozen" do
+  it "raises FrozenError if frozen" do
     @class.freeze
-    -> { @class.make_alias :uno, :public_one }.should raise_error(frozen_error_class)
+    -> { @class.make_alias :uno, :public_one }.should.raise(FrozenError)
   end
 
   it "converts the names using #to_str" do
@@ -66,22 +78,24 @@ describe "Module#alias_method" do
   end
 
   it "raises a TypeError when the given name can't be converted using to_str" do
-    -> { @class.make_alias mock('x'), :public_one }.should raise_error(TypeError)
+    -> { @class.make_alias mock('x'), :public_one }.should.raise(TypeError)
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      -> { @class.alias_method :ichi, :public_one }.should raise_error(NoMethodError)
-    end
+  it "raises a NoMethodError if the given name raises a NoMethodError during type coercion using to_str" do
+    obj = mock("mock-name")
+    obj.should_receive(:to_str).and_raise(NoMethodError)
+    -> { @class.make_alias obj, :public_one }.should.raise(NoMethodError)
   end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:alias_method, false)
-    end
+
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:alias_method)
   end
 
-  it "returns self" do
-    @class.send(:alias_method, :checking_return_value, :public_one).should equal(@class)
+  describe "returned value" do
+    it "returns symbol of the defined method name" do
+      @class.send(:alias_method, :checking_return_value, :public_one).should.equal?(:checking_return_value)
+      @class.send(:alias_method, 'checking_return_value', :public_one).should.equal?(:checking_return_value)
+    end
   end
 
   it "works in module" do
@@ -90,14 +104,14 @@ describe "Module#alias_method" do
 
   it "works on private module methods in a module that has been reopened" do
     ModuleSpecs::ReopeningModule.foo.should == true
-    -> { ModuleSpecs::ReopeningModule.foo2 }.should_not raise_error(NoMethodError)
+    -> { ModuleSpecs::ReopeningModule.foo2 }.should_not.raise(NoMethodError)
   end
 
   it "accesses a method defined on Object from Kernel" do
-    Kernel.should_not have_public_instance_method(:module_specs_public_method_on_object)
+    Kernel.public_instance_methods(true).should_not.include?(:module_specs_public_method_on_object)
 
-    Kernel.should have_public_instance_method(:module_specs_alias_on_kernel)
-    Object.should have_public_instance_method(:module_specs_alias_on_kernel)
+    Kernel.public_instance_methods(false).should.include?(:module_specs_alias_on_kernel)
+    Object.public_instance_methods(true).should.include?(:module_specs_alias_on_kernel)
   end
 
   it "can call a method with super aliased twice" do
@@ -116,42 +130,42 @@ describe "Module#alias_method" do
 
     it "keeps initialize private when aliasing" do
       @class.make_alias(:initialize, :public_one)
-      @class.private_instance_methods.include?(:initialize).should be_true
+      @class.private_instance_methods.include?(:initialize).should == true
 
       @subclass.make_alias(:initialize, :public_one)
-      @subclass.private_instance_methods.include?(:initialize).should be_true
+      @subclass.private_instance_methods.include?(:initialize).should == true
     end
 
     it "keeps initialize_copy private when aliasing" do
       @class.make_alias(:initialize_copy, :public_one)
-      @class.private_instance_methods.include?(:initialize_copy).should be_true
+      @class.private_instance_methods.include?(:initialize_copy).should == true
 
       @subclass.make_alias(:initialize_copy, :public_one)
-      @subclass.private_instance_methods.include?(:initialize_copy).should be_true
+      @subclass.private_instance_methods.include?(:initialize_copy).should == true
     end
 
     it "keeps initialize_clone private when aliasing" do
       @class.make_alias(:initialize_clone, :public_one)
-      @class.private_instance_methods.include?(:initialize_clone).should be_true
+      @class.private_instance_methods.include?(:initialize_clone).should == true
 
       @subclass.make_alias(:initialize_clone, :public_one)
-      @subclass.private_instance_methods.include?(:initialize_clone).should be_true
+      @subclass.private_instance_methods.include?(:initialize_clone).should == true
     end
 
     it "keeps initialize_dup private when aliasing" do
       @class.make_alias(:initialize_dup, :public_one)
-      @class.private_instance_methods.include?(:initialize_dup).should be_true
+      @class.private_instance_methods.include?(:initialize_dup).should == true
 
       @subclass.make_alias(:initialize_dup, :public_one)
-      @subclass.private_instance_methods.include?(:initialize_dup).should be_true
+      @subclass.private_instance_methods.include?(:initialize_dup).should == true
     end
 
     it "keeps respond_to_missing? private when aliasing" do
       @class.make_alias(:respond_to_missing?, :public_one)
-      @class.private_instance_methods.include?(:respond_to_missing?).should be_true
+      @class.private_instance_methods.include?(:respond_to_missing?).should == true
 
       @subclass.make_alias(:respond_to_missing?, :public_one)
-      @subclass.private_instance_methods.include?(:respond_to_missing?).should be_true
+      @subclass.private_instance_methods.include?(:respond_to_missing?).should == true
     end
   end
 end
diff --git a/spec/ruby/core/module/allocate_spec.rb b/spec/ruby/core/module/allocate_spec.rb
deleted file mode 100644
index 3b2c4119c3..0000000000
--- a/spec/ruby/core/module/allocate_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Module.allocate" do
-  it "returns an instance of Module" do
-    mod = Module.allocate
-    mod.should be_an_instance_of(Module)
-  end
-
-  it "returns a fully-formed instance of Module" do
-    mod = Module.allocate
-    mod.constants.should_not == nil
-    mod.methods.should_not == nil
-  end
-end
diff --git a/spec/ruby/core/module/ancestors_spec.rb b/spec/ruby/core/module/ancestors_spec.rb
index 5e4c196206..f85884a4f3 100644
--- a/spec/ruby/core/module/ancestors_spec.rb
+++ b/spec/ruby/core/module/ancestors_spec.rb
@@ -7,27 +7,45 @@ describe "Module#ancestors" do
     ModuleSpecs.ancestors.should == [ModuleSpecs]
     ModuleSpecs::Basic.ancestors.should == [ModuleSpecs::Basic]
     ModuleSpecs::Super.ancestors.should == [ModuleSpecs::Super, ModuleSpecs::Basic]
-    ModuleSpecs.without_test_modules(ModuleSpecs::Parent.ancestors).should ==
-      [ModuleSpecs::Parent, Object, Kernel, BasicObject]
-    ModuleSpecs.without_test_modules(ModuleSpecs::Child.ancestors).should ==
-      [ModuleSpecs::Child, ModuleSpecs::Super, ModuleSpecs::Basic, ModuleSpecs::Parent, Object, Kernel, BasicObject]
+    if defined?(Ruby::Box) && Ruby::Box.enabled?
+      ModuleSpecs.without_test_modules(ModuleSpecs::Parent.ancestors).should ==
+        [ModuleSpecs::Parent, Object, Ruby::Box::Loader, Kernel, BasicObject]
+      ModuleSpecs.without_test_modules(ModuleSpecs::Child.ancestors).should ==
+        [ModuleSpecs::Child, ModuleSpecs::Super, ModuleSpecs::Basic, ModuleSpecs::Parent, Object, Ruby::Box::Loader, Kernel, BasicObject]
+    else
+      ModuleSpecs.without_test_modules(ModuleSpecs::Parent.ancestors).should ==
+        [ModuleSpecs::Parent, Object, Kernel, BasicObject]
+      ModuleSpecs.without_test_modules(ModuleSpecs::Child.ancestors).should ==
+        [ModuleSpecs::Child, ModuleSpecs::Super, ModuleSpecs::Basic, ModuleSpecs::Parent, Object, Kernel, BasicObject]
+    end
   end
 
   it "returns only modules and classes" do
-    class << ModuleSpecs::Child; self; end.ancestors.should include(ModuleSpecs::Internal, Class, Module, Object, Kernel)
+    class << ModuleSpecs::Child; self; end.ancestors.to_set.should >= Set[ModuleSpecs::Internal, Class, Module, Object, Kernel]
   end
 
   it "has 1 entry per module or class" do
     ModuleSpecs::Parent.ancestors.should == ModuleSpecs::Parent.ancestors.uniq
   end
 
+  it "returns a module that is included later into a nested module as well" do
+    m1 = Module.new
+    m2 = Module.new
+    m3 = Module.new do
+      include m2
+    end
+    m2.include m1 # should be after m3 includes m2
+
+    m3.ancestors.should == [m3, m2, m1]
+  end
+
   describe "when called on a singleton class" do
     it "includes the singleton classes of ancestors" do
       parent  = Class.new
       child   = Class.new(parent)
       schild  = child.singleton_class
 
-      schild.ancestors.should include(schild,
+      schild.ancestors.to_set.should >= Set[schild,
                                       parent.singleton_class,
                                       Object.singleton_class,
                                       BasicObject.singleton_class,
@@ -35,14 +53,14 @@ describe "Module#ancestors" do
                                       Module,
                                       Object,
                                       Kernel,
-                                      BasicObject)
+                                      BasicObject]
 
     end
 
     describe 'for a standalone module' do
       it 'does not include Class' do
         s_mod = ModuleSpecs.singleton_class
-        s_mod.ancestors.should_not include(Class)
+        s_mod.ancestors.should_not.include?(Class)
       end
 
       it 'does not include other singleton classes' do
@@ -51,19 +69,19 @@ describe "Module#ancestors" do
         s_object = Object.singleton_class
         s_basic_object = BasicObject.singleton_class
 
-        s_standalone_mod.ancestors.should_not include(s_module, s_object, s_basic_object)
+        (s_standalone_mod.ancestors & [s_module, s_object, s_basic_object]).should.empty?
       end
 
       it 'includes its own singleton class' do
         s_mod = ModuleSpecs.singleton_class
 
-        s_mod.ancestors.should include(s_mod)
+        s_mod.ancestors.should.include?(s_mod)
       end
 
       it 'includes standard chain' do
         s_mod = ModuleSpecs.singleton_class
 
-        s_mod.ancestors.should include(Module, Object, Kernel, BasicObject)
+        s_mod.ancestors.to_set.should >= Set[Module, Object, Kernel, BasicObject]
       end
     end
   end
diff --git a/spec/ruby/core/module/append_features_spec.rb b/spec/ruby/core/module/append_features_spec.rb
index 584aa11dfa..4d2207330d 100644
--- a/spec/ruby/core/module/append_features_spec.rb
+++ b/spec/ruby/core/module/append_features_spec.rb
@@ -3,18 +3,18 @@ require_relative 'fixtures/classes'
 
 describe "Module#append_features" do
   it "is a private method" do
-    Module.should have_private_instance_method(:append_features)
+    Module.private_instance_methods(false).should.include?(:append_features)
   end
 
   describe "on Class" do
     it "is undefined" do
-      Class.should_not have_private_instance_method(:append_features, true)
+      Class.private_instance_methods(true).should_not.include?(:append_features)
     end
 
     it "raises a TypeError if calling after rebinded to Class" do
       -> {
         Module.instance_method(:append_features).bind(Class.new).call Module.new
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 
@@ -39,35 +39,23 @@ describe "Module#append_features" do
   it "raises an ArgumentError on a cyclic include" do
     -> {
       ModuleSpecs::CyclicAppendA.send(:append_features, ModuleSpecs::CyclicAppendA)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       ModuleSpecs::CyclicAppendB.send(:append_features, ModuleSpecs::CyclicAppendA)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
   end
 
-  it "copies own tainted status to the given module" do
-    other = Module.new
-    Module.new.taint.send :append_features, other
-    other.tainted?.should be_true
-  end
-
-  it "copies own untrusted status to the given module" do
-    other = Module.new
-    Module.new.untrust.send :append_features, other
-    other.untrusted?.should be_true
-  end
-
   describe "when other is frozen" do
     before :each do
       @receiver = Module.new
       @other = Module.new.freeze
     end
 
-    it "raises a #{frozen_error_class} before appending self" do
-      -> { @receiver.send(:append_features, @other) }.should raise_error(frozen_error_class)
-      @other.ancestors.should_not include(@receiver)
+    it "raises a FrozenError before appending self" do
+      -> { @receiver.send(:append_features, @other) }.should.raise(FrozenError)
+      @other.ancestors.should_not.include?(@receiver)
     end
   end
 end
diff --git a/spec/ruby/core/module/attr_accessor_spec.rb b/spec/ruby/core/module/attr_accessor_spec.rb
index ce95ccd487..a608760cf2 100644
--- a/spec/ruby/core/module/attr_accessor_spec.rb
+++ b/spec/ruby/core/module/attr_accessor_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/attr_added'
 
 describe "Module#attr_accessor" do
   it "creates a getter and setter for each given attribute name" do
@@ -33,10 +34,23 @@ describe "Module#attr_accessor" do
       attr_accessor :spec_attr_accessor
     end
 
-    -> { true.spec_attr_accessor = "a" }.should raise_error(RuntimeError)
+    -> { true.spec_attr_accessor = "a" }.should.raise(FrozenError)
   end
 
-  it "converts non string/symbol/fixnum names to strings using to_str" do
+  it "raises FrozenError if the receiver if frozen" do
+    c = Class.new do
+      attr_accessor :foo
+    end
+    obj = c.new
+    obj.foo = 1
+    obj.foo.should == 1
+
+    obj.freeze
+    -> { obj.foo = 42 }.should.raise(FrozenError)
+    obj.foo.should == 1
+  end
+
+  it "converts non string/symbol names to strings using to_str" do
     (o = mock('test')).should_receive(:to_str).any_number_of_times.and_return("test")
     c = Class.new do
       attr_accessor o
@@ -48,9 +62,9 @@ describe "Module#attr_accessor" do
 
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     o = mock('o')
-    -> { Class.new { attr_accessor o } }.should raise_error(TypeError)
+    -> { Class.new { attr_accessor o } }.should.raise(TypeError)
     (o = mock('123')).should_receive(:to_str).and_return(123)
-    -> { Class.new { attr_accessor o } }.should raise_error(TypeError)
+    -> { Class.new { attr_accessor o } }.should.raise(TypeError)
   end
 
   it "applies current visibility to methods created" do
@@ -59,39 +73,40 @@ describe "Module#attr_accessor" do
       attr_accessor :foo
     end
 
-    -> { c.new.foo }.should raise_error(NoMethodError)
-    -> { c.new.foo=1 }.should raise_error(NoMethodError)
+    -> { c.new.foo }.should.raise(NoMethodError)
+    -> { c.new.foo=1 }.should.raise(NoMethodError)
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:attr_accessor, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:attr_accessor)
   end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:attr_accessor, false)
+
+  it "returns an array of defined method names as symbols" do
+    Class.new do
+      (attr_accessor :foo, 'bar').should == [:foo, :foo=, :bar, :bar=]
     end
   end
 
   describe "on immediates" do
     before :each do
-      class Fixnum
+      class Integer
         attr_accessor :foobar
       end
     end
 
     after :each do
-      if Fixnum.method_defined?(:foobar)
-        Fixnum.send(:remove_method, :foobar)
+      if Integer.method_defined?(:foobar)
+        Integer.send(:remove_method, :foobar)
       end
-      if Fixnum.method_defined?(:foobar=)
-        Fixnum.send(:remove_method, :foobar=)
+      if Integer.method_defined?(:foobar=)
+        Integer.send(:remove_method, :foobar=)
       end
     end
 
     it "can read through the accessor" do
-      1.foobar.should be_nil
+      1.foobar.should == nil
     end
   end
+
+  it_behaves_like :module_attr_added, :attr_accessor
 end
diff --git a/spec/ruby/core/module/attr_reader_spec.rb b/spec/ruby/core/module/attr_reader_spec.rb
index 082bc03b60..2b4ca2100e 100644
--- a/spec/ruby/core/module/attr_reader_spec.rb
+++ b/spec/ruby/core/module/attr_reader_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/attr_added'
 
 describe "Module#attr_reader" do
   it "creates a getter for each given attribute name" do
@@ -29,10 +30,10 @@ describe "Module#attr_reader" do
       attr_reader :spec_attr_reader
     end
 
-    -> { true.instance_variable_set("@spec_attr_reader", "a") }.should raise_error(RuntimeError)
+    -> { true.instance_variable_set("@spec_attr_reader", "a") }.should.raise(RuntimeError)
   end
 
-  it "converts non string/symbol/fixnum names to strings using to_str" do
+  it "converts non string/symbol names to strings using to_str" do
     (o = mock('test')).should_receive(:to_str).any_number_of_times.and_return("test")
     c = Class.new do
       attr_reader o
@@ -44,9 +45,9 @@ describe "Module#attr_reader" do
 
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     o = mock('o')
-    -> { Class.new { attr_reader o } }.should raise_error(TypeError)
+    -> { Class.new { attr_reader o } }.should.raise(TypeError)
     (o = mock('123')).should_receive(:to_str).and_return(123)
-    -> { Class.new { attr_reader o } }.should raise_error(TypeError)
+    -> { Class.new { attr_reader o } }.should.raise(TypeError)
   end
 
   it "applies current visibility to methods created" do
@@ -55,17 +56,18 @@ describe "Module#attr_reader" do
       attr_reader :foo
     end
 
-    -> { c.new.foo }.should raise_error(NoMethodError)
+    -> { c.new.foo }.should.raise(NoMethodError)
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:attr_reader, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:attr_reader)
   end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:attr_reader, false)
+
+  it "returns an array of defined method names as symbols" do
+    Class.new do
+      (attr_reader :foo, 'bar').should == [:foo, :bar]
     end
   end
+
+  it_behaves_like :module_attr_added, :attr_reader
 end
diff --git a/spec/ruby/core/module/attr_spec.rb b/spec/ruby/core/module/attr_spec.rb
index 20316a3d39..d696864955 100644
--- a/spec/ruby/core/module/attr_spec.rb
+++ b/spec/ruby/core/module/attr_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/attr_added'
 
 describe "Module#attr" do
   before :each do
@@ -89,8 +90,8 @@ describe "Module#attr" do
       attr :foo, true
     end
 
-    -> { c.new.foo }.should raise_error(NoMethodError)
-    -> { c.new.foo=1 }.should raise_error(NoMethodError)
+    -> { c.new.foo }.should.raise(NoMethodError)
+    -> { c.new.foo=1 }.should.raise(NoMethodError)
   end
 
   it "creates a getter but no setter for all given attribute names" do
@@ -120,20 +121,20 @@ describe "Module#attr" do
       attr :foo, :bar
     end
 
-    -> { c.new.foo }.should raise_error(NoMethodError)
-    -> { c.new.bar }.should raise_error(NoMethodError)
+    -> { c.new.foo }.should.raise(NoMethodError)
+    -> { c.new.bar }.should.raise(NoMethodError)
   end
 
-  it "converts non string/symbol/fixnum names to strings using to_str" do
+  it "converts non string/symbol names to strings using to_str" do
     (o = mock('test')).should_receive(:to_str).any_number_of_times.and_return("test")
     Class.new { attr o }.new.respond_to?("test").should == true
   end
 
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     o = mock('o')
-    -> { Class.new { attr o } }.should raise_error(TypeError)
+    -> { Class.new { attr o } }.should.raise(TypeError)
     (o = mock('123')).should_receive(:to_str).and_return(123)
-    -> { Class.new { attr o } }.should raise_error(TypeError)
+    -> { Class.new { attr o } }.should.raise(TypeError)
   end
 
   it "with a boolean argument emits a warning when $VERBOSE is true" do
@@ -142,14 +143,17 @@ describe "Module#attr" do
     }.should complain(/boolean argument is obsoleted/, verbose: true)
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:attr, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:attr)
   end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:attr, false)
+
+  it "returns an array of defined method names as symbols" do
+    Class.new do
+      (attr :foo, 'bar').should == [:foo, :bar]
+      (attr :baz, false).should == [:baz]
+      (attr :qux, true).should == [:qux, :qux=]
     end
   end
+
+  it_behaves_like :module_attr_added, :attr
 end
diff --git a/spec/ruby/core/module/attr_writer_spec.rb b/spec/ruby/core/module/attr_writer_spec.rb
index 3b110cecf7..6089b52495 100644
--- a/spec/ruby/core/module/attr_writer_spec.rb
+++ b/spec/ruby/core/module/attr_writer_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/attr_added'
 
 describe "Module#attr_writer" do
   it "creates a setter for each given attribute name" do
@@ -29,10 +30,20 @@ describe "Module#attr_writer" do
       attr_writer :spec_attr_writer
     end
 
-    -> { true.spec_attr_writer = "a" }.should raise_error(RuntimeError)
+    -> { true.spec_attr_writer = "a" }.should.raise(FrozenError)
   end
 
-  it "converts non string/symbol/fixnum names to strings using to_str" do
+  it "raises FrozenError if the receiver if frozen" do
+    c = Class.new do
+      attr_writer :foo
+    end
+    obj = c.new
+    obj.freeze
+
+    -> { obj.foo = 42 }.should.raise(FrozenError)
+  end
+
+  it "converts non string/symbol names to strings using to_str" do
     (o = mock('test')).should_receive(:to_str).any_number_of_times.and_return("test")
     c = Class.new do
       attr_writer o
@@ -44,9 +55,9 @@ describe "Module#attr_writer" do
 
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     o = mock('test1')
-    -> { Class.new { attr_writer o } }.should raise_error(TypeError)
+    -> { Class.new { attr_writer o } }.should.raise(TypeError)
     (o = mock('123')).should_receive(:to_str).and_return(123)
-    -> { Class.new { attr_writer o } }.should raise_error(TypeError)
+    -> { Class.new { attr_writer o } }.should.raise(TypeError)
   end
 
   it "applies current visibility to methods created" do
@@ -55,17 +66,18 @@ describe "Module#attr_writer" do
       attr_writer :foo
     end
 
-    -> { c.new.foo=1 }.should raise_error(NoMethodError)
+    -> { c.new.foo=1 }.should.raise(NoMethodError)
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:attr_writer, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:attr_writer)
   end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:attr_writer, false)
+
+  it "returns an array of defined method names as symbols" do
+    Class.new do
+      (attr_writer :foo, 'bar').should == [:foo=, :bar=]
     end
   end
+
+  it_behaves_like :module_attr_added, :attr_writer
 end
diff --git a/spec/ruby/core/module/autoload_relative_spec.rb b/spec/ruby/core/module/autoload_relative_spec.rb
new file mode 100644
index 0000000000..2e7d85496b
--- /dev/null
+++ b/spec/ruby/core/module/autoload_relative_spec.rb
@@ -0,0 +1,128 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# Specs for Module#autoload_relative
+module ModuleSpecs
+  module AutoloadRelative
+    # Will be used for testing
+  end
+end
+
+ruby_version_is "4.1" do
+  describe "Module#autoload_relative" do
+    before :each do
+      @loaded_features = $".dup
+    end
+
+    after :each do
+      $".replace @loaded_features
+    end
+
+    it "is a public method" do
+      Module.public_instance_methods(false).should.include?(:autoload_relative)
+    end
+
+    it "registers a file to load relative to the current file the first time the named constant is accessed" do
+      ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeA, "fixtures/autoload_relative_a.rb"
+      path = ModuleSpecs::Autoload.autoload?(:AutoloadRelativeA)
+      path.should_not == nil
+      path.should.end_with?("autoload_relative_a.rb")
+      File.exist?(path).should == true
+    end
+
+    it "loads the registered file when the constant is accessed" do
+      ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeB, "fixtures/autoload_relative_a.rb"
+      ModuleSpecs::Autoload::AutoloadRelativeB.should.is_a?(Module)
+    end
+
+    it "returns nil" do
+      ModuleSpecs::Autoload.autoload_relative(:AutoloadRelativeC, "fixtures/autoload_relative_a.rb").should == nil
+    end
+
+    it "registers a file to load the first time the named constant is accessed" do
+      module ModuleSpecs::Autoload::AutoloadRelativeTest
+        autoload_relative :D, "fixtures/autoload_relative_a.rb"
+      end
+      path = ModuleSpecs::Autoload::AutoloadRelativeTest.autoload?(:D)
+      path.should_not == nil
+      path.should.end_with?("autoload_relative_a.rb")
+    end
+
+    it "sets the autoload constant in the constants table" do
+      ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeTableTest, "fixtures/autoload_relative_a.rb"
+      ModuleSpecs::Autoload.should.const_defined?(:AutoloadRelativeTableTest, false)
+    end
+
+    it "calls #to_path on non-String filenames" do
+      name = mock("autoload_relative mock")
+      name.should_receive(:to_path).and_return("fixtures/autoload_relative_a.rb")
+      ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeToPath, name
+      ModuleSpecs::Autoload.autoload?(:AutoloadRelativeToPath).should_not == nil
+    end
+
+    it "calls #to_str on non-String filenames" do
+      name = mock("autoload_relative mock")
+      name.should_receive(:to_str).and_return("fixtures/autoload_relative_a.rb")
+      ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeToStr, name
+      ModuleSpecs::Autoload.autoload?(:AutoloadRelativeToStr).should_not == nil
+    end
+
+    it "raises a TypeError if the filename argument is not a String or pathname" do
+      -> {
+        ModuleSpecs::Autoload.autoload_relative :AutoloadRelativeTypError, nil
+      }.should.raise(TypeError)
+    end
+
+    it "raises a NameError if the constant name is not valid" do
+      -> {
+        ModuleSpecs::Autoload.autoload_relative :invalid_name, "fixtures/autoload_relative_a.rb"
+      }.should.raise(NameError)
+    end
+
+    it "raises an ArgumentError if the constant name starts with a lowercase letter" do
+      -> {
+        ModuleSpecs::Autoload.autoload_relative :autoload, "fixtures/autoload_relative_a.rb"
+      }.should.raise(NameError)
+    end
+
+    it "raises LoadError if called from eval without file context" do
+      -> {
+        ModuleSpecs::Autoload.module_eval('autoload_relative :EvalTest, "fixtures/autoload_relative_a.rb"')
+      }.should.raise(LoadError, /autoload_relative called without file context/)
+    end
+
+    it "can autoload in instance_eval with a file context" do
+      path = nil
+      ModuleSpecs::Autoload.instance_eval(<<-CODE, __FILE__, __LINE__)
+        autoload_relative :InstanceEvalTest, "fixtures/autoload_relative_a.rb"
+        path = autoload?(:InstanceEvalTest)
+      CODE
+      path.should_not == nil
+      path.should.end_with?("autoload_relative_a.rb")
+    end
+
+    it "resolves paths relative to the file where it's called" do
+      # Using fixtures/autoload_relative_a.rb which exists
+      ModuleSpecs::Autoload.autoload_relative :RelativePathTest, "fixtures/autoload_relative_a.rb"
+      path = ModuleSpecs::Autoload.autoload?(:RelativePathTest)
+      path.should.include?("fixtures")
+      path.should.end_with?("autoload_relative_a.rb")
+    end
+
+    it "can load nested directory paths" do
+      ModuleSpecs::Autoload.autoload_relative :NestedPath, "fixtures/autoload_relative_a.rb"
+      path = ModuleSpecs::Autoload.autoload?(:NestedPath)
+      path.should_not == nil
+      File.exist?(path).should == true
+    end
+
+    describe "interoperability with autoload?" do
+      it "returns the absolute path with autoload?" do
+        ModuleSpecs::Autoload.autoload_relative :QueryTest, "fixtures/autoload_relative_a.rb"
+        path = ModuleSpecs::Autoload.autoload?(:QueryTest)
+        # Should be an absolute path
+        Pathname.new(path).absolute?.should == true
+      end
+    end
+end
+end
diff --git a/spec/ruby/core/module/autoload_spec.rb b/spec/ruby/core/module/autoload_spec.rb
index df434e8e60..057237a92f 100644
--- a/spec/ruby/core/module/autoload_spec.rb
+++ b/spec/ruby/core/module/autoload_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
+require_relative '../../fixtures/code_loading'
 require_relative 'fixtures/classes'
-require 'thread'
 
 describe "Module#autoload?" do
   it "returns the name of the file that will be autoloaded" do
@@ -9,7 +9,7 @@ describe "Module#autoload?" do
   end
 
   it "returns nil if no file has been registered for a constant" do
-    ModuleSpecs::Autoload.autoload?(:Manualload).should be_nil
+    ModuleSpecs::Autoload.autoload?(:Manualload).should == nil
   end
 
   it "returns the name of the file that will be autoloaded if an ancestor defined that autoload" do
@@ -17,30 +17,21 @@ describe "Module#autoload?" do
     ModuleSpecs::Autoload::Child.autoload?(:AnotherAutoload).should == "another_autoload.rb"
   end
 
-  ruby_version_is "2.7" do
-    it "returns nil if an ancestor defined that autoload but recursion is disabled" do
-      ModuleSpecs::Autoload::Parent.autoload :InheritedAutoload, "inherited_autoload.rb"
-      ModuleSpecs::Autoload::Child.autoload?(:InheritedAutoload, false).should be_nil
-    end
+  it "returns nil if an ancestor defined that autoload but recursion is disabled" do
+    ModuleSpecs::Autoload::Parent.autoload :InheritedAutoload, "inherited_autoload.rb"
+    ModuleSpecs::Autoload::Child.autoload?(:InheritedAutoload, false).should == nil
+  end
 
-    it "returns the name of the file that will be loaded if recursion is disabled but the autoload is defined on the classs itself" do
-      ModuleSpecs::Autoload::Child.autoload :ChildAutoload, "child_autoload.rb"
-      ModuleSpecs::Autoload::Child.autoload?(:ChildAutoload, false).should == "child_autoload.rb"
-    end
+  it "returns the name of the file that will be loaded if recursion is disabled but the autoload is defined on the class itself" do
+    ModuleSpecs::Autoload::Child.autoload :ChildAutoload, "child_autoload.rb"
+    ModuleSpecs::Autoload::Child.autoload?(:ChildAutoload, false).should == "child_autoload.rb"
   end
 end
 
 describe "Module#autoload" do
   before :all do
     @non_existent = fixture __FILE__, "no_autoload.rb"
-
-    # Require RubyGems eagerly, to ensure #require is already the RubyGems
-    # version, before starting #autoload specs which snapshot #require, and
-    # could end up redefining #require as the original core Kernel#require.
-    begin
-      require "rubygems"
-    rescue LoadError
-    end
+    CodeLoadingSpecs.preload_rubygems
   end
 
   before :each do
@@ -64,7 +55,7 @@ describe "Module#autoload" do
 
   it "sets the autoload constant in the constants table" do
     ModuleSpecs::Autoload.autoload :B, @non_existent
-    ModuleSpecs::Autoload.should have_constant(:B)
+    ModuleSpecs::Autoload.should.const_defined?(:B, false)
   end
 
   it "can be overridden with a second autoload on the same constant" do
@@ -80,7 +71,7 @@ describe "Module#autoload" do
   end
 
   it "loads the registered constant when it is accessed" do
-    ModuleSpecs::Autoload.should_not have_constant(:X)
+    ModuleSpecs::Autoload.should_not.const_defined?(:X)
     ModuleSpecs::Autoload.autoload :X, fixture(__FILE__, "autoload_x.rb")
     @remove << :X
     ModuleSpecs::Autoload::X.should == :x
@@ -91,7 +82,7 @@ describe "Module#autoload" do
     ModuleSpecs::Autoload::DynClass = cls
     @remove << :DynClass
 
-    ScratchPad.recorded.should be_nil
+    ScratchPad.recorded.should == nil
     ModuleSpecs::Autoload::DynClass::C.new.loaded.should == :dynclass_c
     ScratchPad.recorded.should == :loaded
   end
@@ -101,7 +92,7 @@ describe "Module#autoload" do
     ModuleSpecs::Autoload::DynModule = mod
     @remove << :DynModule
 
-    ScratchPad.recorded.should be_nil
+    ScratchPad.recorded.should == nil
     ModuleSpecs::Autoload::DynModule::D.new.loaded.should == :dynmodule_d
     ScratchPad.recorded.should == :loaded
   end
@@ -140,7 +131,7 @@ describe "Module#autoload" do
     @remove << :I
     ModuleSpecs::Autoload.const_set :I, 3
     ModuleSpecs::Autoload::I.should == 3
-    ScratchPad.recorded.should be_nil
+    ScratchPad.recorded.should == nil
   end
 
   it "loads a file with .rb extension when passed the name without the extension" do
@@ -153,7 +144,7 @@ describe "Module#autoload" do
     main = TOPLEVEL_BINDING.eval("self")
     main.should_receive(:require).with("module_autoload_not_exist.rb")
     # The constant won't be defined since require is mocked to do nothing
-    -> { ModuleSpecs::Autoload::ModuleAutoloadCallsRequire }.should raise_error(NameError)
+    -> { ModuleSpecs::Autoload::ModuleAutoloadCallsRequire }.should.raise(NameError)
   end
 
   it "does not load the file if the file is manually required" do
@@ -165,9 +156,9 @@ describe "Module#autoload" do
     ScratchPad.recorded.should == :loaded
     ScratchPad.clear
 
-    ModuleSpecs::Autoload::KHash.should be_kind_of(Class)
+    ModuleSpecs::Autoload::KHash.should.is_a?(Class)
     ModuleSpecs::Autoload::KHash::K.should == :autoload_k
-    ScratchPad.recorded.should be_nil
+    ScratchPad.recorded.should == nil
   end
 
   it "ignores the autoload request if the file is already loaded" do
@@ -180,7 +171,7 @@ describe "Module#autoload" do
 
     ModuleSpecs::Autoload.autoload :S, filename
     @remove << :S
-    ModuleSpecs::Autoload.autoload?(:S).should be_nil
+    ModuleSpecs::Autoload.autoload?(:S).should == nil
   end
 
   it "retains the autoload even if the request to require fails" do
@@ -191,7 +182,7 @@ describe "Module#autoload" do
 
     -> {
       require filename
-    }.should raise_error(LoadError)
+    }.should.raise(LoadError)
 
     ModuleSpecs::Autoload.autoload?(:NotThere).should == filename
   end
@@ -210,6 +201,13 @@ describe "Module#autoload" do
     ModuleSpecs::Autoload.use_ex1.should == :good
   end
 
+  it "considers an autoload constant as loaded when autoload is called for/from the current file" do
+    filename = fixture(__FILE__, "autoload_during_require_current_file.rb")
+    require filename
+
+    ScratchPad.recorded.should == nil
+  end
+
   describe "interacting with defined?" do
     it "does not load the file when referring to the constant in defined?" do
       module ModuleSpecs::Autoload::Dog
@@ -217,9 +215,9 @@ describe "Module#autoload" do
       end
 
       defined?(ModuleSpecs::Autoload::Dog::R).should == "constant"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
 
-      ModuleSpecs::Autoload::Dog.should have_constant(:R)
+      ModuleSpecs::Autoload::Dog.should.const_defined?(:R, false)
     end
 
     it "loads an autoloaded parent when referencing a nested constant" do
@@ -237,7 +235,7 @@ describe "Module#autoload" do
         autoload :BadParent, fixture(__FILE__, "autoload_exception.rb")
       end
 
-      defined?(ModuleSpecs::Autoload::BadParent::Nested).should be_nil
+      defined?(ModuleSpecs::Autoload::BadParent::Nested).should == nil
       ScratchPad.recorded.should == :exception
     end
   end
@@ -294,6 +292,32 @@ describe "Module#autoload" do
       ScratchPad.recorded.should == [nil, nil]
       @check.call.should == ["constant", nil]
     end
+
+    it "does not raise an error if the autoload constant was not defined" do
+      module ModuleSpecs::Autoload
+        autoload :RequiredDirectlyNoConstant, fixture(__FILE__, "autoload_required_directly_no_constant.rb")
+      end
+      @path = fixture(__FILE__, "autoload_required_directly_no_constant.rb")
+      @remove << :RequiredDirectlyNoConstant
+      @check = -> {
+        [
+            defined?(ModuleSpecs::Autoload::RequiredDirectlyNoConstant),
+            ModuleSpecs::Autoload.constants(false).include?(:RequiredDirectlyNoConstant),
+            ModuleSpecs::Autoload.const_defined?(:RequiredDirectlyNoConstant),
+            ModuleSpecs::Autoload.autoload?(:RequiredDirectlyNoConstant)
+        ]
+      }
+      ScratchPad.record @check
+      @check.call.should == ["constant", true, true, @path]
+      $:.push File.dirname(@path)
+      begin
+        require "autoload_required_directly_no_constant.rb"
+      ensure
+        $:.pop
+      end
+      ScratchPad.recorded.should == [nil, true, false, nil]
+      @check.call.should == [nil, true, false, nil]
+    end
   end
 
   describe "after the autoload is triggered by require" do
@@ -318,6 +342,29 @@ describe "Module#autoload" do
     end
   end
 
+  def check_before_during_thread_after(const, &check)
+    before = check.call
+    to_autoload_thread, from_autoload_thread = Queue.new, Queue.new
+    ScratchPad.record -> {
+      from_autoload_thread.push check.call
+      to_autoload_thread.pop
+    }
+    t = Thread.new {
+      in_loading_thread = from_autoload_thread.pop
+      in_other_thread = check.call
+      to_autoload_thread.push :done
+      [in_loading_thread, in_other_thread]
+    }
+    in_loading_thread, in_other_thread = nil
+    begin
+      ModuleSpecs::Autoload.const_get(const)
+    ensure
+      in_loading_thread, in_other_thread = t.value
+    end
+    after = check.call
+    [before, in_loading_thread, in_other_thread, after]
+  end
+
   describe "during the autoload before the constant is assigned" do
     before :each do
       @path = fixture(__FILE__, "autoload_during_autoload.rb")
@@ -326,72 +373,97 @@ describe "Module#autoload" do
       raise unless ModuleSpecs::Autoload.autoload?(:DuringAutoload) == @path
     end
 
-    def check_before_during_thread_after(&check)
-      before = check.call
-      to_autoload_thread, from_autoload_thread = Queue.new, Queue.new
-      ScratchPad.record -> {
-        from_autoload_thread.push check.call
-        to_autoload_thread.pop
-      }
-      t = Thread.new {
-        in_loading_thread = from_autoload_thread.pop
-        in_other_thread = check.call
-        to_autoload_thread.push :done
-        [in_loading_thread, in_other_thread]
-      }
-      in_loading_thread, in_other_thread = nil
-      begin
-        ModuleSpecs::Autoload::DuringAutoload
-      ensure
-        in_loading_thread, in_other_thread = t.value
-      end
-      after = check.call
-      [before, in_loading_thread, in_other_thread, after]
-    end
-
     it "returns nil in autoload thread and 'constant' otherwise for defined?" do
-      results = check_before_during_thread_after {
+      results = check_before_during_thread_after(:DuringAutoload) {
         defined?(ModuleSpecs::Autoload::DuringAutoload)
       }
       results.should == ['constant', nil, 'constant', 'constant']
     end
 
     it "keeps the constant in Module#constants" do
-      results = check_before_during_thread_after {
+      results = check_before_during_thread_after(:DuringAutoload) {
         ModuleSpecs::Autoload.constants(false).include?(:DuringAutoload)
       }
       results.should == [true, true, true, true]
     end
 
     it "returns false in autoload thread and true otherwise for Module#const_defined?" do
-      results = check_before_during_thread_after {
+      results = check_before_during_thread_after(:DuringAutoload) {
         ModuleSpecs::Autoload.const_defined?(:DuringAutoload, false)
       }
       results.should == [true, false, true, true]
     end
 
     it "returns nil in autoload thread and returns the path in other threads for Module#autoload?" do
-      results = check_before_during_thread_after {
+      results = check_before_during_thread_after(:DuringAutoload) {
         ModuleSpecs::Autoload.autoload?(:DuringAutoload)
       }
       results.should == [@path, nil, @path, nil]
     end
   end
 
+  describe "during the autoload after the constant is assigned" do
+    before :each do
+      @path = fixture(__FILE__, "autoload_during_autoload_after_define.rb")
+      ModuleSpecs::Autoload.autoload :DuringAutoloadAfterDefine, @path
+      @autoload_location = [__FILE__, __LINE__ - 1]
+      @const_location = [@path, 2]
+      @remove << :DuringAutoloadAfterDefine
+      raise unless ModuleSpecs::Autoload.autoload?(:DuringAutoloadAfterDefine) == @path
+    end
+
+    it "returns 'constant' in both threads" do
+      results = check_before_during_thread_after(:DuringAutoloadAfterDefine) {
+        defined?(ModuleSpecs::Autoload::DuringAutoloadAfterDefine)
+      }
+      results.should == ['constant', 'constant', 'constant', 'constant']
+    end
+
+    it "Module#constants include the autoloaded in both threads" do
+      results = check_before_during_thread_after(:DuringAutoloadAfterDefine) {
+        ModuleSpecs::Autoload.constants(false).include?(:DuringAutoloadAfterDefine)
+      }
+      results.should == [true, true, true, true]
+    end
+
+    it "Module#const_defined? returns true in both threads" do
+      results = check_before_during_thread_after(:DuringAutoloadAfterDefine) {
+        ModuleSpecs::Autoload.const_defined?(:DuringAutoloadAfterDefine, false)
+      }
+      results.should == [true, true, true, true]
+    end
+
+    it "returns nil in autoload thread and returns the path in other threads for Module#autoload?" do
+      results = check_before_during_thread_after(:DuringAutoloadAfterDefine) {
+        ModuleSpecs::Autoload.autoload?(:DuringAutoloadAfterDefine)
+      }
+      results.should == [@path, nil, @path, nil]
+    end
+
+    ruby_bug("#20188", ""..."3.4") do
+      it "returns the real constant location in autoload thread and returns the autoload location in other threads for Module#const_source_location" do
+        results = check_before_during_thread_after(:DuringAutoloadAfterDefine) {
+          ModuleSpecs::Autoload.const_source_location(:DuringAutoloadAfterDefine)
+        }
+        results.should == [@autoload_location, @const_location, @autoload_location, @const_location]
+      end
+    end
+  end
+
   it "does not remove the constant from Module#constants if load fails and keeps it as an autoload" do
     ModuleSpecs::Autoload.autoload :Fail, @non_existent
 
     ModuleSpecs::Autoload.const_defined?(:Fail).should == true
-    ModuleSpecs::Autoload.should have_constant(:Fail)
+    ModuleSpecs::Autoload.should.const_defined?(:Fail, false)
     ModuleSpecs::Autoload.autoload?(:Fail).should == @non_existent
 
-    -> { ModuleSpecs::Autoload::Fail }.should raise_error(LoadError)
+    -> { ModuleSpecs::Autoload::Fail }.should.raise(LoadError)
 
-    ModuleSpecs::Autoload.should have_constant(:Fail)
+    ModuleSpecs::Autoload.should.const_defined?(:Fail, false)
     ModuleSpecs::Autoload.const_defined?(:Fail).should == true
     ModuleSpecs::Autoload.autoload?(:Fail).should == @non_existent
 
-    -> { ModuleSpecs::Autoload::Fail }.should raise_error(LoadError)
+    -> { ModuleSpecs::Autoload::Fail }.should.raise(LoadError)
   end
 
   it "does not remove the constant from Module#constants if load raises a RuntimeError and keeps it as an autoload" do
@@ -400,35 +472,35 @@ describe "Module#autoload" do
     ModuleSpecs::Autoload.autoload :Raise, path
 
     ModuleSpecs::Autoload.const_defined?(:Raise).should == true
-    ModuleSpecs::Autoload.should have_constant(:Raise)
+    ModuleSpecs::Autoload.should.const_defined?(:Raise, false)
     ModuleSpecs::Autoload.autoload?(:Raise).should == path
 
-    -> { ModuleSpecs::Autoload::Raise }.should raise_error(RuntimeError)
+    -> { ModuleSpecs::Autoload::Raise }.should.raise(RuntimeError)
     ScratchPad.recorded.should == [:raise]
 
-    ModuleSpecs::Autoload.should have_constant(:Raise)
+    ModuleSpecs::Autoload.should.const_defined?(:Raise, false)
     ModuleSpecs::Autoload.const_defined?(:Raise).should == true
     ModuleSpecs::Autoload.autoload?(:Raise).should == path
 
-    -> { ModuleSpecs::Autoload::Raise }.should raise_error(RuntimeError)
+    -> { ModuleSpecs::Autoload::Raise }.should.raise(RuntimeError)
     ScratchPad.recorded.should == [:raise, :raise]
   end
 
-  it "does not remove the constant from Module#constants if the loaded file does not define it, but leaves it as 'undefined'" do
+  it "removes the constant from Module#constants if the loaded file does not define it" do
     path = fixture(__FILE__, "autoload_o.rb")
     ScratchPad.record []
     ModuleSpecs::Autoload.autoload :O, path
 
     ModuleSpecs::Autoload.const_defined?(:O).should == true
-    ModuleSpecs::Autoload.should have_constant(:O)
+    ModuleSpecs::Autoload.should.const_defined?(:O, false)
     ModuleSpecs::Autoload.autoload?(:O).should == path
 
-    -> { ModuleSpecs::Autoload::O }.should raise_error(NameError)
+    -> { ModuleSpecs::Autoload::O }.should.raise(NameError)
 
-    ModuleSpecs::Autoload.should have_constant(:O)
     ModuleSpecs::Autoload.const_defined?(:O).should == false
+    ModuleSpecs::Autoload.should_not.const_defined?(:O)
     ModuleSpecs::Autoload.autoload?(:O).should == nil
-    -> { ModuleSpecs::Autoload.const_get(:O) }.should raise_error(NameError)
+    -> { ModuleSpecs::Autoload.const_get(:O) }.should.raise(NameError)
   end
 
   it "does not try to load the file again if the loaded file did not define the constant" do
@@ -436,13 +508,13 @@ describe "Module#autoload" do
     ScratchPad.record []
     ModuleSpecs::Autoload.autoload :NotDefinedByFile, path
 
-    -> { ModuleSpecs::Autoload::NotDefinedByFile }.should raise_error(NameError)
+    -> { ModuleSpecs::Autoload::NotDefinedByFile }.should.raise(NameError)
     ScratchPad.recorded.should == [:loaded]
-    -> { ModuleSpecs::Autoload::NotDefinedByFile }.should raise_error(NameError)
+    -> { ModuleSpecs::Autoload::NotDefinedByFile }.should.raise(NameError)
     ScratchPad.recorded.should == [:loaded]
 
     Thread.new {
-      -> { ModuleSpecs::Autoload::NotDefinedByFile }.should raise_error(NameError)
+      -> { ModuleSpecs::Autoload::NotDefinedByFile }.should.raise(NameError)
     }.join
     ScratchPad.recorded.should == [:loaded]
   end
@@ -452,7 +524,7 @@ describe "Module#autoload" do
       autoload :R, fixture(__FILE__, "autoload.rb")
       defined?(R).should == 'constant'
     end
-    ModuleSpecs::Autoload::Q.should have_constant(:R)
+    ModuleSpecs::Autoload::Q.should.const_defined?(:R, false)
   end
 
   it "does not load the file when removing an autoload constant" do
@@ -460,15 +532,13 @@ describe "Module#autoload" do
       autoload :R, fixture(__FILE__, "autoload.rb")
       remove_const :R
     end
-    ModuleSpecs::Autoload::Q.should_not have_constant(:R)
+    ModuleSpecs::Autoload::Q.should_not.const_defined?(:R)
   end
 
   it "does not load the file when accessing the constants table of the module" do
     ModuleSpecs::Autoload.autoload :P, @non_existent
-    ModuleSpecs::Autoload.const_defined?(:P).should be_true
-    ruby_bug "[Bug #15780]", ""..."2.7" do
-      ModuleSpecs::Autoload.const_defined?("P").should be_true
-    end
+    ModuleSpecs::Autoload.const_defined?(:P).should == true
+    ModuleSpecs::Autoload.const_defined?("P").should == true
   end
 
   it "loads the file when opening a module that is the autoloaded constant" do
@@ -503,8 +573,8 @@ describe "Module#autoload" do
           DeclaredAndDefinedInParent.should == :declared_and_defined_in_parent
 
           # The constant is really in Autoload, not Autoload::LexicalScope
-          self.should_not have_constant(:DeclaredAndDefinedInParent)
-          -> { const_get(:DeclaredAndDefinedInParent) }.should raise_error(NameError)
+          self.should_not.const_defined?(:DeclaredAndDefinedInParent)
+          -> { const_get(:DeclaredAndDefinedInParent) }.should.raise(NameError)
         end
         DeclaredAndDefinedInParent.should == :declared_and_defined_in_parent
       end
@@ -527,14 +597,41 @@ describe "Module#autoload" do
         # Basically, the parent autoload constant remains in a "undefined" state
         self.autoload?(:DeclaredInParentDefinedInCurrent).should == nil
         const_defined?(:DeclaredInParentDefinedInCurrent).should == false
-        self.should have_constant(:DeclaredInParentDefinedInCurrent)
-        -> { DeclaredInParentDefinedInCurrent }.should raise_error(NameError)
+        -> { DeclaredInParentDefinedInCurrent }.should.raise(NameError)
 
         ModuleSpecs::Autoload::LexicalScope.send(:remove_const, :DeclaredInParentDefinedInCurrent)
       end
     end
 
-    it "and fails when finding the undefined autoload constant in the current scope when declared in current and defined in parent" do
+    it "warns once in verbose mode if the constant was defined in a parent scope" do
+      ScratchPad.record -> {
+        ModuleSpecs::DeclaredInCurrentDefinedInParent = :declared_in_current_defined_in_parent
+      }
+
+      module ModuleSpecs
+        module Autoload
+          autoload :DeclaredInCurrentDefinedInParent, fixture(__FILE__, "autoload_callback.rb")
+          self.autoload?(:DeclaredInCurrentDefinedInParent).should == fixture(__FILE__, "autoload_callback.rb")
+          const_defined?(:DeclaredInCurrentDefinedInParent).should == true
+
+          -> {
+            DeclaredInCurrentDefinedInParent
+          }.should complain(
+            /Expected .*autoload_callback.rb to define ModuleSpecs::Autoload::DeclaredInCurrentDefinedInParent but it didn't/,
+            verbose: true,
+          )
+
+          -> {
+            DeclaredInCurrentDefinedInParent
+          }.should_not complain(/.*/, verbose: true)
+          self.autoload?(:DeclaredInCurrentDefinedInParent).should == nil
+          const_defined?(:DeclaredInCurrentDefinedInParent).should == false
+          ModuleSpecs.const_defined?(:DeclaredInCurrentDefinedInParent).should == true
+        end
+      end
+    end
+
+    it "looks up in parent scope after failed autoload" do
       @remove << :DeclaredInCurrentDefinedInParent
       module ModuleSpecs::Autoload
         ScratchPad.record -> {
@@ -543,12 +640,11 @@ describe "Module#autoload" do
 
         class LexicalScope
           autoload :DeclaredInCurrentDefinedInParent, fixture(__FILE__, "autoload_callback.rb")
-          -> { DeclaredInCurrentDefinedInParent }.should raise_error(NameError)
+          -> { DeclaredInCurrentDefinedInParent }.should_not.raise(NameError)
           # Basically, the autoload constant remains in a "undefined" state
           self.autoload?(:DeclaredInCurrentDefinedInParent).should == nil
           const_defined?(:DeclaredInCurrentDefinedInParent).should == false
-          self.should have_constant(:DeclaredInCurrentDefinedInParent)
-          -> { const_get(:DeclaredInCurrentDefinedInParent) }.should raise_error(NameError)
+          -> { const_get(:DeclaredInCurrentDefinedInParent) }.should.raise(NameError)
         end
 
         DeclaredInCurrentDefinedInParent.should == :declared_in_current_defined_in_parent
@@ -618,8 +714,23 @@ describe "Module#autoload" do
           end
         end
       end
-      ModuleSpecs::Autoload.r.should be_kind_of(ModuleSpecs::Autoload::MetaScope)
+      ModuleSpecs::Autoload.r.should.is_a?(ModuleSpecs::Autoload::MetaScope)
+    end
+  end
+
+  it "should trigger the autoload when using `private_constant`" do
+    @remove << :DynClass
+    module ModuleSpecs::Autoload
+      autoload :DynClass, fixture(__FILE__, "autoload_c.rb")
+      private_constant :DynClass
+
+      ScratchPad.recorded.should == nil
+
+      DynClass::C.new.loaded.should == :dynclass_c
+      ScratchPad.recorded.should == :loaded
     end
+
+    -> { ModuleSpecs::Autoload::DynClass }.should.raise(NameError, /private constant/)
   end
 
   # [ruby-core:19127] [ruby-core:29941]
@@ -634,7 +745,7 @@ describe "Module#autoload" do
     end
     @remove << :W
 
-    ModuleSpecs::Autoload::W::Y.should be_kind_of(Class)
+    ModuleSpecs::Autoload::W::Y.should.is_a?(Class)
     ScratchPad.recorded.should == :loaded
   end
 
@@ -649,7 +760,28 @@ describe "Module#autoload" do
     -> {
       Kernel.require fixture(__FILE__, "autoload_during_require.rb")
     }.should_not complain(verbose: true)
-    ModuleSpecs::Autoload::AutoloadDuringRequire.should be_kind_of(Class)
+    ModuleSpecs::Autoload::AutoloadDuringRequire.should.is_a?(Class)
+  end
+
+  it "does not call #require a second time and does not warn if feature sets and trigger autoload on itself" do
+    main = TOPLEVEL_BINDING.eval("self")
+    main.should_not_receive(:require)
+
+    -> {
+      Kernel.require fixture(__FILE__, "autoload_self_during_require.rb")
+    }.should_not complain(verbose: true)
+    ModuleSpecs::Autoload::AutoloadSelfDuringRequire.should.is_a?(Class)
+  end
+
+  it "handles multiple autoloads in the same file" do
+    $LOAD_PATH.unshift(File.expand_path('../fixtures/multi', __FILE__))
+    begin
+      require 'foo/bar_baz'
+      ModuleSpecs::Autoload::Foo::Bar.should.is_a?(Class)
+      ModuleSpecs::Autoload::Foo::Baz.should.is_a?(Class)
+    ensure
+      $LOAD_PATH.shift
+    end
   end
 
   it "calls #to_path on non-string filenames" do
@@ -659,19 +791,19 @@ describe "Module#autoload" do
   end
 
   it "raises an ArgumentError when an empty filename is given" do
-    -> { ModuleSpecs.autoload :A, "" }.should raise_error(ArgumentError)
+    -> { ModuleSpecs.autoload :A, "" }.should.raise(ArgumentError)
   end
 
   it "raises a NameError when the constant name starts with a lower case letter" do
-    -> { ModuleSpecs.autoload "a", @non_existent }.should raise_error(NameError)
+    -> { ModuleSpecs.autoload "a", @non_existent }.should.raise(NameError)
   end
 
   it "raises a NameError when the constant name starts with a number" do
-    -> { ModuleSpecs.autoload "1two", @non_existent }.should raise_error(NameError)
+    -> { ModuleSpecs.autoload "1two", @non_existent }.should.raise(NameError)
   end
 
   it "raises a NameError when the constant name has a space in it" do
-    -> { ModuleSpecs.autoload "a name", @non_existent }.should raise_error(NameError)
+    -> { ModuleSpecs.autoload "a name", @non_existent }.should.raise(NameError)
   end
 
   it "shares the autoload request across dup'ed copies of modules" do
@@ -688,7 +820,7 @@ describe "Module#autoload" do
     mod2.autoload?(:T).should == filename
 
     mod1::T.should == :autoload_t
-    -> { mod2::T }.should raise_error(NameError)
+    -> { mod2::T }.should.raise(NameError)
   end
 
   it "raises a TypeError if opening a class with a different superclass than the class defined in the autoload file" do
@@ -699,27 +831,27 @@ describe "Module#autoload" do
     -> do
       class ModuleSpecs::Autoload::Z < ModuleSpecs::Autoload::ZZ
       end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if not passed a String or object responding to #to_path for the filename" do
     name = mock("autoload_name.rb")
 
-    -> { ModuleSpecs::Autoload.autoload :Str, name }.should raise_error(TypeError)
+    -> { ModuleSpecs::Autoload.autoload :Str, name }.should.raise(TypeError)
   end
 
   it "calls #to_path on non-String filename arguments" do
     name = mock("autoload_name.rb")
     name.should_receive(:to_path).and_return("autoload_name.rb")
 
-    -> { ModuleSpecs::Autoload.autoload :Str, name }.should_not raise_error
+    -> { ModuleSpecs::Autoload.autoload :Str, name }.should_not.raise
   end
 
   describe "on a frozen module" do
-    it "raises a #{frozen_error_class} before setting the name" do
+    it "raises a FrozenError before setting the name" do
       frozen_module = Module.new.freeze
-      -> { frozen_module.autoload :Foo, @non_existent }.should raise_error(frozen_error_class)
-      frozen_module.should_not have_constant(:Foo)
+      -> { frozen_module.autoload :Foo, @non_existent }.should.raise(FrozenError)
+      frozen_module.should_not.const_defined?(:Foo)
     end
   end
 
@@ -784,7 +916,7 @@ describe "Module#autoload" do
       t1_val.should == 1
       t2_val.should == t1_val
 
-      t2_exc.should be_nil
+      t2_exc.should == nil
     end
 
     # https://bugs.ruby-lang.org/issues/10892
@@ -816,7 +948,7 @@ describe "Module#autoload" do
 
             begin
               Object.const_get(mod_name).foo
-            rescue NoMethodError
+            rescue NameError, NoMethodError # rubocop:disable Lint/ShadowedException
               barrier.disable!
               break false
             end
@@ -824,8 +956,8 @@ describe "Module#autoload" do
         end
       end
 
-      # check that no thread got a NoMethodError because of partially loaded module
-      threads.all? {|t| t.value}.should be_true
+      # check that no thread got a NameError or NoMethodError because of partially loaded module
+      threads.all? {|t| t.value}.should == true
 
       # check that the autoloaded file was evaled exactly once
       ScratchPad.recorded.get.should == mod_count
@@ -833,6 +965,8 @@ describe "Module#autoload" do
       mod_names.each do |mod_name|
         Object.send(:remove_const, mod_name)
       end
+    ensure
+      threads.each(&:join) if threads
     end
 
     it "raises a NameError in each thread if the constant is not set" do
@@ -856,7 +990,7 @@ describe "Module#autoload" do
 
       start = true
       threads.each { |t|
-        t.value.should be_an_instance_of(NameError)
+        t.value.should.instance_of?(NameError)
       }
     end
 
@@ -881,7 +1015,7 @@ describe "Module#autoload" do
 
       start = true
       threads.each { |t|
-        t.value.should be_an_instance_of(LoadError)
+        t.value.should.instance_of?(LoadError)
       }
     end
   end
diff --git a/spec/ruby/core/module/class_variable_defined_spec.rb b/spec/ruby/core/module/class_variable_defined_spec.rb
index f867d383c3..dedce9589a 100644
--- a/spec/ruby/core/module/class_variable_defined_spec.rb
+++ b/spec/ruby/core/module/class_variable_defined_spec.rb
@@ -19,13 +19,13 @@ describe "Module#class_variable_defined?" do
     obj = mock("metaclass class variable")
     meta = obj.singleton_class
     meta.send :class_variable_set, :@@var, 1
-    meta.send(:class_variable_defined?, :@@var).should be_true
+    meta.send(:class_variable_defined?, :@@var).should == true
   end
 
   it "returns false if the class variable is not defined in a metaclass" do
     obj = mock("metaclass class variable")
     meta = obj.singleton_class
-    meta.class_variable_defined?(:@@var).should be_false
+    meta.class_variable_defined?(:@@var).should == false
   end
 
   it "returns true if a class variables with the given name is defined in an included module" do
@@ -44,14 +44,14 @@ describe "Module#class_variable_defined?" do
 
     -> {
       c.class_variable_defined?(:invalid_name)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
 
     -> {
       c.class_variable_defined?("@invalid_name")
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
-  it "converts a non string/symbol/fixnum name to string using to_str" do
+  it "converts a non string/symbol name to string using to_str" do
     c = Class.new { class_variable_set :@@class_var, "test" }
     (o = mock('@@class_var')).should_receive(:to_str).and_return("@@class_var")
     c.class_variable_defined?(o).should == true
@@ -62,11 +62,11 @@ describe "Module#class_variable_defined?" do
     o = mock('123')
     -> {
       c.class_variable_defined?(o)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
 
     o.should_receive(:to_str).and_return(123)
     -> {
       c.class_variable_defined?(o)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/class_variable_get_spec.rb b/spec/ruby/core/module/class_variable_get_spec.rb
index 79d22a506b..13f06cb94a 100644
--- a/spec/ruby/core/module/class_variable_get_spec.rb
+++ b/spec/ruby/core/module/class_variable_get_spec.rb
@@ -15,8 +15,8 @@ describe "Module#class_variable_get" do
 
   it "raises a NameError for a class variable named '@@'" do
     c = Class.new
-    -> { c.send(:class_variable_get, "@@") }.should raise_error(NameError)
-    -> { c.send(:class_variable_get, :"@@") }.should raise_error(NameError)
+    -> { c.send(:class_variable_get, "@@") }.should.raise(NameError)
+    -> { c.send(:class_variable_get, :"@@") }.should.raise(NameError)
   end
 
   it "raises a NameError for a class variables with the given name defined in an extended module" do
@@ -24,7 +24,7 @@ describe "Module#class_variable_get" do
     c.extend ModuleSpecs::MVars
     -> {
       c.send(:class_variable_get, "@@mvar")
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "returns class variables defined in the class body and accessed in the metaclass" do
@@ -49,18 +49,18 @@ describe "Module#class_variable_get" do
   it "raises a NameError when an uninitialized class variable is accessed" do
     c = Class.new
     [:@@no_class_var, "@@no_class_var"].each do |cvar|
-      ->  { c.send(:class_variable_get, cvar) }.should raise_error(NameError)
+      ->  { c.send(:class_variable_get, cvar) }.should.raise(NameError)
     end
   end
 
   it "raises a NameError when the given name is not allowed" do
     c = Class.new
 
-    -> { c.send(:class_variable_get, :invalid_name)   }.should raise_error(NameError)
-    -> { c.send(:class_variable_get, "@invalid_name") }.should raise_error(NameError)
+    -> { c.send(:class_variable_get, :invalid_name)   }.should.raise(NameError)
+    -> { c.send(:class_variable_get, "@invalid_name") }.should.raise(NameError)
   end
 
-  it "converts a non string/symbol/fixnum name to string using to_str" do
+  it "converts a non string/symbol name to string using to_str" do
     c = Class.new { class_variable_set :@@class_var, "test" }
     (o = mock('@@class_var')).should_receive(:to_str).and_return("@@class_var")
     c.send(:class_variable_get, o).should == "test"
@@ -69,8 +69,8 @@ describe "Module#class_variable_get" do
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     c = Class.new { class_variable_set :@@class_var, "test" }
     o = mock('123')
-    -> { c.send(:class_variable_get, o) }.should raise_error(TypeError)
+    -> { c.send(:class_variable_get, o) }.should.raise(TypeError)
     o.should_receive(:to_str).and_return(123)
-    -> { c.send(:class_variable_get, o) }.should raise_error(TypeError)
+    -> { c.send(:class_variable_get, o) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/class_variable_set_spec.rb b/spec/ruby/core/module/class_variable_set_spec.rb
index 204bbaf75e..a3d759767b 100644
--- a/spec/ruby/core/module/class_variable_set_spec.rb
+++ b/spec/ruby/core/module/class_variable_set_spec.rb
@@ -25,13 +25,13 @@ describe "Module#class_variable_set" do
     c.send(:class_variable_get, "@@mvar").should == :new_mvar
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     -> {
       Class.new.freeze.send(:class_variable_set, :@@test, "test")
-    }.should raise_error(frozen_error_class)
+    }.should.raise(FrozenError)
     -> {
       Module.new.freeze.send(:class_variable_set, :@@test, "test")
-    }.should raise_error(frozen_error_class)
+    }.should.raise(FrozenError)
   end
 
   it "raises a NameError when the given name is not allowed" do
@@ -39,13 +39,13 @@ describe "Module#class_variable_set" do
 
     -> {
       c.send(:class_variable_set, :invalid_name, "test")
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
     -> {
       c.send(:class_variable_set, "@invalid_name", "test")
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
-  it "converts a non string/symbol/fixnum name to string using to_str" do
+  it "converts a non string/symbol name to string using to_str" do
     (o = mock('@@class_var')).should_receive(:to_str).and_return("@@class_var")
     c = Class.new
     c.send(:class_variable_set, o, "test")
@@ -55,8 +55,8 @@ describe "Module#class_variable_set" do
   it "raises a TypeError when the given names can't be converted to strings using to_str" do
     c = Class.new { class_variable_set :@@class_var, "test" }
     o = mock('123')
-    -> { c.send(:class_variable_set, o, "test") }.should raise_error(TypeError)
+    -> { c.send(:class_variable_set, o, "test") }.should.raise(TypeError)
     o.should_receive(:to_str).and_return(123)
-    -> { c.send(:class_variable_set, o, "test") }.should raise_error(TypeError)
+    -> { c.send(:class_variable_set, o, "test") }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/class_variables_spec.rb b/spec/ruby/core/module/class_variables_spec.rb
index fd7aa93aa8..9529df48ae 100644
--- a/spec/ruby/core/module/class_variables_spec.rb
+++ b/spec/ruby/core/module/class_variables_spec.rb
@@ -3,8 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "Module#class_variables" do
   it "returns an Array with the names of class variables of self" do
-    ModuleSpecs::ClassVars::A.class_variables.should include(:@@a_cvar)
-    ModuleSpecs::ClassVars::M.class_variables.should include(:@@m_cvar)
+    ModuleSpecs::ClassVars::A.class_variables.should.include?(:@@a_cvar)
+    ModuleSpecs::ClassVars::M.class_variables.should.include?(:@@m_cvar)
   end
 
   it "returns an Array of Symbols of class variable names defined in a metaclass" do
@@ -15,12 +15,20 @@ describe "Module#class_variables" do
   end
 
   it "returns an Array with names of class variables defined in metaclasses" do
-    ModuleSpecs::CVars.class_variables.should include(:@@cls, :@@meta)
+    ModuleSpecs::CVars.class_variables.to_set.should >= Set[:@@cls, :@@meta]
   end
 
   it "does not return class variables defined in extended modules" do
     c = Class.new
     c.extend ModuleSpecs::MVars
-    c.class_variables.should_not include(:@@mvar)
+    c.class_variables.should_not.include?(:@@mvar)
+  end
+
+  it "returns the correct class variables when inherit is given" do
+    ModuleSpecs::SubCVars.class_variables(false).should == [:@@sub]
+    ModuleSpecs::SubCVars.new.singleton_class.class_variables(false).should == []
+
+    ModuleSpecs::SubCVars.class_variables(true).should == [:@@sub, :@@cls, :@@meta]
+    ModuleSpecs::SubCVars.new.singleton_class.class_variables(true).should ==  [:@@sub, :@@cls, :@@meta]
   end
 end
diff --git a/spec/ruby/core/module/const_added_spec.rb b/spec/ruby/core/module/const_added_spec.rb
new file mode 100644
index 0000000000..b60af7a2e8
--- /dev/null
+++ b/spec/ruby/core/module/const_added_spec.rb
@@ -0,0 +1,238 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'fixtures/const_added'
+
+describe "Module#const_added" do
+  it "is a private instance method" do
+    Module.private_instance_methods(false).should.include?(:const_added)
+  end
+
+  it "returns nil in the default implementation" do
+    Module.new do
+      const_added(:TEST).should == nil
+    end
+  end
+
+  it "for a class defined with the `class` keyword, const_added runs before inherited" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(_)
+        ScratchPad << :const_added
+      end
+    end
+
+    parent = Class.new do
+      def self.inherited(_)
+        ScratchPad << :inherited
+      end
+    end
+
+    class mod::C < parent; end
+
+    ScratchPad.recorded.should == [:const_added, :inherited]
+  end
+
+  it "the superclass of a class assigned to a constant is set before const_added is called" do
+    ScratchPad.record []
+
+    parent = Class.new do
+      def self.const_added(name)
+        ScratchPad << name
+        ScratchPad << const_get(name).superclass
+      end
+    end
+
+    class parent::C < parent; end
+
+    ScratchPad.recorded.should == [:C, parent]
+  end
+
+  it "is called when a new constant is assigned on self" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+    end
+
+    mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+      TEST = 1
+    RUBY
+
+    ScratchPad.recorded.should == [:TEST]
+  end
+
+  it "is called when a new constant is assigned on self through const_set" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+    end
+
+    mod.const_set(:TEST, 1)
+
+    ScratchPad.recorded.should == [:TEST]
+  end
+
+  it "is called when a new module is defined under self" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+    end
+
+    mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+      module SubModule
+      end
+
+      module SubModule
+      end
+    RUBY
+
+    ScratchPad.recorded.should == [:SubModule]
+  end
+
+  it "is called when a new module is defined under a named module (assigned to a constant)" do
+    ScratchPad.record []
+
+    ModuleSpecs::ConstAddedSpecs::NamedModule = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+
+      module self::A
+        def self.const_added(name)
+          ScratchPad << name
+        end
+
+        module self::B
+        end
+      end
+    end
+
+    ScratchPad.recorded.should == [:A, :B]
+    ModuleSpecs::ConstAddedSpecs.send :remove_const, :NamedModule
+  end
+
+  it "is called when a new class is defined under self" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+    end
+
+    mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+      class SubClass
+      end
+
+      class SubClass
+      end
+    RUBY
+
+    ScratchPad.recorded.should == [:SubClass]
+  end
+
+  it "is called when a new class is defined under a named module (assigned to a constant)" do
+    ScratchPad.record []
+
+    ModuleSpecs::ConstAddedSpecs::NamedModuleB = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+
+      class self::A
+        def self.const_added(name)
+          ScratchPad << name
+        end
+
+        class self::B
+        end
+      end
+    end
+
+    ScratchPad.recorded.should == [:A, :B]
+    ModuleSpecs::ConstAddedSpecs.send :remove_const, :NamedModuleB
+  end
+
+  it "is called when an autoload is defined" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << name
+      end
+    end
+
+    mod.autoload :Autoload, "foo"
+    ScratchPad.recorded.should == [:Autoload]
+  end
+
+  it "is called with a precise caller location with the line of definition" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        location = caller_locations(1, 1)[0]
+        ScratchPad << location.lineno
+      end
+    end
+
+    line = __LINE__
+    mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+      TEST = 1
+
+      module SubModule
+      end
+
+      class SubClass
+      end
+    RUBY
+
+    mod.const_set(:CONST_SET, 1)
+
+    ScratchPad.recorded.should == [line + 2, line + 4, line + 7, line + 11]
+  end
+
+  it "is called when the constant is already assigned a value" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad.record const_get(name)
+      end
+    end
+
+    mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+      TEST = 123
+    RUBY
+
+    ScratchPad.recorded.should == 123
+  end
+
+  it "records re-definition of existing constants" do
+    ScratchPad.record []
+
+    mod = Module.new do
+      def self.const_added(name)
+        ScratchPad << const_get(name)
+      end
+    end
+
+    -> {
+      mod.module_eval(<<-RUBY, __FILE__, __LINE__ + 1)
+        TEST = 123
+        TEST = 456
+      RUBY
+    }.should complain(/warning: already initialized constant .+::TEST/)
+
+    ScratchPad.recorded.should == [123, 456]
+  end
+end
diff --git a/spec/ruby/core/module/const_defined_spec.rb b/spec/ruby/core/module/const_defined_spec.rb
index 0673adca3d..9d973c2b2b 100644
--- a/spec/ruby/core/module/const_defined_spec.rb
+++ b/spec/ruby/core/module/const_defined_spec.rb
@@ -14,30 +14,40 @@ describe "Module#const_defined?" do
 
   it "returns true if the constant is defined in the receiver's superclass" do
     # CS_CONST4 is defined in the superclass of ChildA
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4).should be_true
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4).should == true
   end
 
-  it "returns true if the constant is defined in a mixed-in module of the receiver" do
+  it "returns true if the constant is defined in a mixed-in module of the receiver's parent" do
     # CS_CONST10 is defined in a module included by ChildA
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST10).should be_true
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST10).should == true
+  end
+
+  it "returns true if the constant is defined in a mixed-in module (with prepends) of the receiver" do
+    # CS_CONST11 is defined in the module included by ContainerPrepend
+    ConstantSpecs::ContainerPrepend.const_defined?(:CS_CONST11).should == true
   end
 
   it "returns true if the constant is defined in Object and the receiver is a module" do
     # CS_CONST1 is defined in Object
-    ConstantSpecs::ModuleA.const_defined?(:CS_CONST1).should be_true
+    ConstantSpecs::ModuleA.const_defined?(:CS_CONST1).should == true
   end
 
   it "returns true if the constant is defined in Object and the receiver is a class that has Object among its ancestors" do
     # CS_CONST1 is defined in Object
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST1).should be_true
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST1).should == true
   end
 
   it "returns false if the constant is defined in the receiver's superclass and the inherit flag is false" do
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, false).should be_false
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, false).should == false
   end
 
   it "returns true if the constant is defined in the receiver's superclass and the inherit flag is true" do
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, true).should be_true
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, true).should == true
+  end
+
+  it "coerces the inherit flag to a boolean" do
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, nil).should == false
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, :true).should == true
   end
 
   it "returns true if the given String names a constant defined in the receiver" do
@@ -48,21 +58,23 @@ describe "Module#const_defined?" do
   end
 
   it "returns true when passed a constant name with unicode characters" do
-    ConstantUnicodeSpecs.const_defined?("CS_CONSTλ").should be_true
+    ConstantUnicodeSpecs.const_defined?("CS_CONSTλ").should == true
   end
 
   it "returns true when passed a constant name with EUC-JP characters" do
     str = "CS_CONSTλ".encode("euc-jp")
     ConstantSpecs.const_set str, 1
-    ConstantSpecs.const_defined?(str).should be_true
+    ConstantSpecs.const_defined?(str).should == true
+  ensure
+    ConstantSpecs.send(:remove_const, str)
   end
 
   it "returns false if the constant is not defined in the receiver, its superclass, or any included modules" do
     # The following constant isn't defined at all.
-    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4726).should be_false
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4726).should == false
     # DETACHED_CONSTANT is defined in ConstantSpecs::Detached, which isn't
     # included by or inherited from ParentA
-    ConstantSpecs::ParentA.const_defined?(:DETACHED_CONSTANT).should be_false
+    ConstantSpecs::ParentA.const_defined?(:DETACHED_CONSTANT).should == false
   end
 
   it "does not call #const_missing if the constant is not defined in the receiver" do
@@ -70,54 +82,67 @@ describe "Module#const_defined?" do
     ConstantSpecs::ClassA.const_defined?(:CS_CONSTX).should == false
   end
 
-  it "calls #to_str to convert the given name to a String" do
-    name = mock("ClassA")
-    name.should_receive(:to_str).and_return("ClassA")
-    ConstantSpecs.const_defined?(name).should == true
+  describe "converts the given name to a String using #to_str" do
+    it "calls #to_str to convert the given name to a String" do
+      name = mock("ClassA")
+      name.should_receive(:to_str).and_return("ClassA")
+      ConstantSpecs.const_defined?(name).should == true
+    end
+
+    it "raises a TypeError if the given name can't be converted to a String" do
+      -> { ConstantSpecs.const_defined?(nil) }.should.raise(TypeError)
+      -> { ConstantSpecs.const_defined?([])  }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to a String" do
+      name = mock("classA")
+      name.should_receive(:to_str).and_raise(NoMethodError)
+      -> { ConstantSpecs.const_defined?(name) }.should.raise(NoMethodError)
+    end
   end
 
   it "special cases Object and checks it's included Modules" do
-    Object.const_defined?(:CS_CONST10).should be_true
+    Object.const_defined?(:CS_CONST10).should == true
   end
 
   it "returns true for toplevel constant when the name begins with '::'" do
-    ConstantSpecs.const_defined?("::Array").should be_true
+    ConstantSpecs.const_defined?("::Array").should == true
   end
 
   it "returns true when passed a scoped constant name" do
-    ConstantSpecs.const_defined?("ClassC::CS_CONST1").should be_true
+    ConstantSpecs.const_defined?("ClassC::CS_CONST1").should == true
   end
 
   it "returns true when passed a scoped constant name for a constant in the inheritance hierarchy and the inherited flag is default" do
-    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2").should be_true
+    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2").should == true
   end
 
   it "returns true when passed a scoped constant name for a constant in the inheritance hierarchy and the inherited flag is true" do
-    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2", true).should be_true
+    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2", true).should == true
   end
 
   it "returns false when passed a scoped constant name for a constant in the inheritance hierarchy and the inherited flag is false" do
-    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2", false).should be_false
+    ConstantSpecs::ClassD.const_defined?("ClassE::CS_CONST2", false).should == false
   end
 
   it "returns false when the name begins with '::' and the toplevel constant does not exist" do
-    ConstantSpecs.const_defined?("::Name").should be_false
+    ConstantSpecs.const_defined?("::Name").should == false
   end
 
   it "raises a NameError if the name does not start with a capital letter" do
-    -> { ConstantSpecs.const_defined? "name" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_defined? "name" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with '_'" do
-    -> { ConstantSpecs.const_defined? "__CONSTX__" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_defined? "__CONSTX__" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with '@'" do
-    -> { ConstantSpecs.const_defined? "@Name" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_defined? "@Name" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with '!'" do
-    -> { ConstantSpecs.const_defined? "!Name" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_defined? "!Name" }.should.raise(NameError)
   end
 
   it "returns true or false for the nested name" do
@@ -130,15 +155,15 @@ describe "Module#const_defined?" do
 
   it "raises a NameError if the name contains non-alphabetic characters except '_'" do
     ConstantSpecs.const_defined?("CS_CONSTX").should == false
-    -> { ConstantSpecs.const_defined? "Name=" }.should raise_error(NameError)
-    -> { ConstantSpecs.const_defined? "Name?" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_defined? "Name=" }.should.raise(NameError)
+    -> { ConstantSpecs.const_defined? "Name?" }.should.raise(NameError)
   end
 
   it "raises a TypeError if conversion to a String by calling #to_str fails" do
     name = mock('123')
-    -> { ConstantSpecs.const_defined? name }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_defined? name }.should.raise(TypeError)
 
     name.should_receive(:to_str).and_return(123)
-    -> { ConstantSpecs.const_defined? name }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_defined? name }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/const_get_spec.rb b/spec/ruby/core/module/const_get_spec.rb
index 0a6702903f..68b5594faa 100644
--- a/spec/ruby/core/module/const_get_spec.rb
+++ b/spec/ruby/core/module/const_get_spec.rb
@@ -9,28 +9,28 @@ describe "Module#const_get" do
   end
 
   it "raises a NameError if no constant is defined in the search path" do
-    -> { ConstantSpecs.const_get :CS_CONSTX }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get :CS_CONSTX }.should.raise(NameError)
   end
 
   it "raises a NameError with the not found constant symbol" do
     error_inspection = -> e { e.name.should == :CS_CONSTX }
-    -> { ConstantSpecs.const_get :CS_CONSTX }.should raise_error(NameError, &error_inspection)
+    -> { ConstantSpecs.const_get :CS_CONSTX }.should.raise(NameError, &error_inspection)
   end
 
   it "raises a NameError if the name does not start with a capital letter" do
-    -> { ConstantSpecs.const_get "name" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get "name" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with a non-alphabetic character" do
-    -> { ConstantSpecs.const_get "__CONSTX__" }.should raise_error(NameError)
-    -> { ConstantSpecs.const_get "@CS_CONST1" }.should raise_error(NameError)
-    -> { ConstantSpecs.const_get "!CS_CONST1" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get "__CONSTX__" }.should.raise(NameError)
+    -> { ConstantSpecs.const_get "@CS_CONST1" }.should.raise(NameError)
+    -> { ConstantSpecs.const_get "!CS_CONST1" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name contains non-alphabetic characters except '_'" do
     Object.const_get("CS_CONST1").should == :const1
-    -> { ConstantSpecs.const_get "CS_CONST1=" }.should raise_error(NameError)
-    -> { ConstantSpecs.const_get "CS_CONST1?" }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get "CS_CONST1=" }.should.raise(NameError)
+    -> { ConstantSpecs.const_get "CS_CONST1?" }.should.raise(NameError)
   end
 
   it "calls #to_str to convert the given name to a String" do
@@ -41,10 +41,10 @@ describe "Module#const_get" do
 
   it "raises a TypeError if conversion to a String by calling #to_str fails" do
     name = mock('123')
-    -> { ConstantSpecs.const_get(name) }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_get(name) }.should.raise(TypeError)
 
     name.should_receive(:to_str).and_return(123)
-    -> { ConstantSpecs.const_get(name) }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_get(name) }.should.raise(TypeError)
   end
 
   it "calls #const_missing on the receiver if unable to locate the constant" do
@@ -55,21 +55,21 @@ describe "Module#const_get" do
   it "does not search the singleton class of a Class or Module" do
     -> do
       ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST14)
-    end.should raise_error(NameError)
-    -> { ConstantSpecs.const_get(:CS_CONST14) }.should raise_error(NameError)
+    end.should.raise(NameError)
+    -> { ConstantSpecs.const_get(:CS_CONST14) }.should.raise(NameError)
   end
 
   it "does not search the containing scope" do
     ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST20).should == :const20_2
     -> do
       ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST5)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the constant is defined in the receiver's superclass and the inherit flag is false" do
     -> do
       ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST4, false)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "searches into the receiver superclasses if the inherit flag is true" do
@@ -79,41 +79,59 @@ describe "Module#const_get" do
   it "raises a NameError when the receiver is a Module, the constant is defined at toplevel and the inherit flag is false" do
     -> do
       ConstantSpecs::ModuleA.const_get(:CS_CONST1, false)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError when the receiver is a Class, the constant is defined at toplevel and the inherit flag is false" do
     -> do
       ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST1, false)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
+  end
+
+  it "coerces the inherit flag to a boolean" do
+    ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST4, :true).should == :const4
+
+    -> do
+      ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST1, nil)
+    end.should.raise(NameError)
   end
 
   it "accepts a toplevel scope qualifier" do
     ConstantSpecs.const_get("::CS_CONST1").should == :const1
   end
 
+  it "accepts a toplevel scope qualifier when inherit is false" do
+    ConstantSpecs.const_get("::CS_CONST1", false).should == :const1
+    -> { ConstantSpecs.const_get("CS_CONST1", false) }.should.raise(NameError)
+  end
+
+  it "returns a constant whose module is defined the toplevel" do
+    ConstantSpecs.const_get("ConstantSpecsTwo::Foo").should == :cs_two_foo
+    ConstantSpecsThree.const_get("ConstantSpecsTwo::Foo").should == :cs_three_foo
+  end
+
   it "accepts a scoped constant name" do
     ConstantSpecs.const_get("ClassA::CS_CONST10").should == :const10_10
   end
 
   it "raises a NameError if the name includes two successive scope separators" do
-    -> { ConstantSpecs.const_get("ClassA::::CS_CONST10") }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get("ClassA::::CS_CONST10") }.should.raise(NameError)
   end
 
   it "raises a NameError if only '::' is passed" do
-    -> { ConstantSpecs.const_get("::") }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get("::") }.should.raise(NameError)
   end
 
   it "raises a NameError if a Symbol has a toplevel scope qualifier" do
-    -> { ConstantSpecs.const_get(:'::CS_CONST1') }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get(:'::CS_CONST1') }.should.raise(NameError)
   end
 
   it "raises a NameError if a Symbol is a scoped constant name" do
-    -> { ConstantSpecs.const_get(:'ClassA::CS_CONST10') }.should raise_error(NameError)
+    -> { ConstantSpecs.const_get(:'ClassA::CS_CONST10') }.should.raise(NameError)
   end
 
   it "does read private constants" do
-     ConstantSpecs.const_get(:CS_PRIVATE).should == :cs_private
+    ConstantSpecs.const_get(:CS_PRIVATE).should == :cs_private
   end
 
   it 'does autoload a constant' do
@@ -132,6 +150,10 @@ describe "Module#const_get" do
     Object.const_get('CSAutoloadD::InnerModule').name.should == 'CSAutoloadD::InnerModule'
   end
 
+  it "raises a NameError when the nested constant does not exist on the module but exists in Object" do
+    -> { Object.const_get('ConstantSpecs::CS_CONST1') }.should.raise(NameError)
+  end
+
   describe "with statically assigned constants" do
     it "searches the immediate class or module first" do
       ConstantSpecs::ClassA.const_get(:CS_CONST10).should == :const10_10
@@ -180,40 +202,60 @@ describe "Module#const_get" do
 
       ConstantSpecs::ContainerA::ChildA::CS_CONST301 = :const301_5
       ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST301).should == :const301_5
+    ensure
+      ConstantSpecs::ClassA.send(:remove_const, :CS_CONST301)
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST301)
+      ConstantSpecs::ParentA.send(:remove_const, :CS_CONST301)
+      ConstantSpecs::ContainerA::ChildA.send(:remove_const, :CS_CONST301)
     end
 
     it "searches a module included in the immediate class before the superclass" do
       ConstantSpecs::ParentB::CS_CONST302 = :const302_1
       ConstantSpecs::ModuleF::CS_CONST302 = :const302_2
       ConstantSpecs::ContainerB::ChildB.const_get(:CS_CONST302).should == :const302_2
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST302)
+      ConstantSpecs::ModuleF.send(:remove_const, :CS_CONST302)
     end
 
     it "searches the superclass before a module included in the superclass" do
       ConstantSpecs::ModuleE::CS_CONST303 = :const303_1
       ConstantSpecs::ParentB::CS_CONST303 = :const303_2
       ConstantSpecs::ContainerB::ChildB.const_get(:CS_CONST303).should == :const303_2
+    ensure
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST303)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST303)
     end
 
     it "searches a module included in the superclass" do
       ConstantSpecs::ModuleA::CS_CONST304 = :const304_1
       ConstantSpecs::ModuleE::CS_CONST304 = :const304_2
       ConstantSpecs::ContainerB::ChildB.const_get(:CS_CONST304).should == :const304_2
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST304)
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST304)
     end
 
     it "searches the superclass chain" do
       ConstantSpecs::ModuleA::CS_CONST305 = :const305
       ConstantSpecs::ContainerB::ChildB.const_get(:CS_CONST305).should == :const305
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST305)
     end
 
     it "returns a toplevel constant when the receiver is a Class" do
       Object::CS_CONST306 = :const306
       ConstantSpecs::ContainerB::ChildB.const_get(:CS_CONST306).should == :const306
+    ensure
+      Object.send(:remove_const, :CS_CONST306)
     end
 
     it "returns a toplevel constant when the receiver is a Module" do
       Object::CS_CONST308 = :const308
       ConstantSpecs.const_get(:CS_CONST308).should == :const308
       ConstantSpecs::ModuleA.const_get(:CS_CONST308).should == :const308
+    ensure
+      Object.send(:remove_const, :CS_CONST308)
     end
 
     it "returns the updated value of a constant" do
@@ -224,6 +266,8 @@ describe "Module#const_get" do
         ConstantSpecs::ClassB::CS_CONST309 = :const309_2
       }.should complain(/already initialized constant/)
       ConstantSpecs::ClassB.const_get(:CS_CONST309).should == :const309_2
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST309)
     end
   end
 end
diff --git a/spec/ruby/core/module/const_missing_spec.rb b/spec/ruby/core/module/const_missing_spec.rb
index 742218281c..80a2caccab 100644
--- a/spec/ruby/core/module/const_missing_spec.rb
+++ b/spec/ruby/core/module/const_missing_spec.rb
@@ -13,7 +13,7 @@ describe "Module#const_missing" do
   it "raises NameError and includes the name of the value that wasn't found" do
     -> {
       ConstantSpecs.const_missing("HelloMissing")
-    }.should raise_error(NameError, /ConstantSpecs::HelloMissing/)
+    }.should.raise(NameError, /ConstantSpecs::HelloMissing/)
   end
 
   it "raises NameError and does not include toplevel Object" do
diff --git a/spec/ruby/core/module/const_set_spec.rb b/spec/ruby/core/module/const_set_spec.rb
index 1b8b86dd04..aa3c6bbcfc 100644
--- a/spec/ruby/core/module/const_set_spec.rb
+++ b/spec/ruby/core/module/const_set_spec.rb
@@ -8,22 +8,29 @@ describe "Module#const_set" do
 
     ConstantSpecs.const_set "CS_CONST402", :const402
     ConstantSpecs.const_get(:CS_CONST402).should == :const402
+  ensure
+    ConstantSpecs.send(:remove_const, :CS_CONST401)
+    ConstantSpecs.send(:remove_const, :CS_CONST402)
   end
 
   it "returns the value set" do
     ConstantSpecs.const_set(:CS_CONST403, :const403).should == :const403
+  ensure
+    ConstantSpecs.send(:remove_const, :CS_CONST403)
   end
 
   it "sets the name of an anonymous module" do
     m = Module.new
     ConstantSpecs.const_set(:CS_CONST1000, m)
     m.name.should == "ConstantSpecs::CS_CONST1000"
+  ensure
+    ConstantSpecs.send(:remove_const, :CS_CONST1000)
   end
 
-  it "does not set the name of a module scoped by an anonymous module" do
+  it "sets the name of a module scoped by an anonymous module" do
     a, b = Module.new, Module.new
     a.const_set :B, b
-    b.name.should be_nil
+    b.name.should.end_with? '::B'
   end
 
   it "sets the name of contained modules when assigning a toplevel anonymous module" do
@@ -38,23 +45,27 @@ describe "Module#const_set" do
     b.name.should == "ModuleSpecs_CS3::B"
     c.name.should == "ModuleSpecs_CS3::B::C"
     d.name.should == "ModuleSpecs_CS3::D"
+  ensure
+    Object.send(:remove_const, :ModuleSpecs_CS3)
   end
 
   it "raises a NameError if the name does not start with a capital letter" do
-    -> { ConstantSpecs.const_set "name", 1 }.should raise_error(NameError)
+    -> { ConstantSpecs.const_set "name", 1 }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with a non-alphabetic character" do
-    -> { ConstantSpecs.const_set "__CONSTX__", 1 }.should raise_error(NameError)
-    -> { ConstantSpecs.const_set "@Name", 1 }.should raise_error(NameError)
-    -> { ConstantSpecs.const_set "!Name", 1 }.should raise_error(NameError)
-    -> { ConstantSpecs.const_set "::Name", 1 }.should raise_error(NameError)
+    -> { ConstantSpecs.const_set "__CONSTX__", 1 }.should.raise(NameError)
+    -> { ConstantSpecs.const_set "@Name", 1 }.should.raise(NameError)
+    -> { ConstantSpecs.const_set "!Name", 1 }.should.raise(NameError)
+    -> { ConstantSpecs.const_set "::Name", 1 }.should.raise(NameError)
   end
 
   it "raises a NameError if the name contains non-alphabetic characters except '_'" do
     ConstantSpecs.const_set("CS_CONST404", :const404).should == :const404
-    -> { ConstantSpecs.const_set "Name=", 1 }.should raise_error(NameError)
-    -> { ConstantSpecs.const_set "Name?", 1 }.should raise_error(NameError)
+    -> { ConstantSpecs.const_set "Name=", 1 }.should.raise(NameError)
+    -> { ConstantSpecs.const_set "Name?", 1 }.should.raise(NameError)
+  ensure
+    ConstantSpecs.send(:remove_const, :CS_CONST404)
   end
 
   it "calls #to_str to convert the given name to a String" do
@@ -62,14 +73,16 @@ describe "Module#const_set" do
     name.should_receive(:to_str).and_return("CS_CONST405")
     ConstantSpecs.const_set(name, :const405).should == :const405
     ConstantSpecs::CS_CONST405.should == :const405
+  ensure
+    ConstantSpecs.send(:remove_const, :CS_CONST405)
   end
 
   it "raises a TypeError if conversion to a String by calling #to_str fails" do
     name = mock('123')
-    -> { ConstantSpecs.const_set name, 1 }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_set name, 1 }.should.raise(TypeError)
 
     name.should_receive(:to_str).and_return(123)
-    -> { ConstantSpecs.const_set name, 1 }.should raise_error(TypeError)
+    -> { ConstantSpecs.const_set name, 1 }.should.raise(TypeError)
   end
 
   describe "when overwriting an existing constant" do
@@ -91,15 +104,14 @@ describe "Module#const_set" do
       mod.const_get(:Foo).should == 1
     end
 
-    it "does not warn if the previous value was undefined" do
+    it "does not warn after a failed autoload" do
       path = fixture(__FILE__, "autoload_o.rb")
       ScratchPad.record []
       mod = Module.new
 
       mod.autoload :Foo, path
-      -> { mod::Foo }.should raise_error(NameError)
+      -> { mod::Foo }.should.raise(NameError)
 
-      mod.should have_constant(:Foo)
       mod.const_defined?(:Foo).should == false
       mod.autoload?(:Foo).should == nil
 
@@ -125,9 +137,9 @@ describe "Module#const_set" do
       @name = :Foo
     end
 
-    it "raises a #{frozen_error_class} before setting the name" do
-      -> { @frozen.const_set @name, nil }.should raise_error(frozen_error_class)
-      @frozen.should_not have_constant(@name)
+    it "raises a FrozenError before setting the name" do
+      -> { @frozen.const_set @name, nil }.should.raise(FrozenError)
+      @frozen.should_not.const_defined?(@name)
     end
   end
 end
diff --git a/spec/ruby/core/module/const_source_location_spec.rb b/spec/ruby/core/module/const_source_location_spec.rb
new file mode 100644
index 0000000000..e6cef727e2
--- /dev/null
+++ b/spec/ruby/core/module/const_source_location_spec.rb
@@ -0,0 +1,281 @@
+require_relative '../../spec_helper'
+require_relative '../../fixtures/constants'
+
+describe "Module#const_source_location" do
+  before do
+    @constants_fixture_path = File.expand_path('../../fixtures/constants.rb', __dir__)
+  end
+
+  describe "with dynamically assigned constants" do
+    it "searches a path in the immediate class or module first" do
+      ConstantSpecs::ClassA::CSL_CONST301 = :const301_1
+      ConstantSpecs::ClassA.const_source_location(:CSL_CONST301).should == [__FILE__, __LINE__ - 1]
+
+      ConstantSpecs::ModuleA::CSL_CONST301 = :const301_2
+      ConstantSpecs::ModuleA.const_source_location(:CSL_CONST301).should == [__FILE__, __LINE__ - 1]
+
+      ConstantSpecs::ParentA::CSL_CONST301 = :const301_3
+      ConstantSpecs::ParentA.const_source_location(:CSL_CONST301).should == [__FILE__, __LINE__ - 1]
+
+      ConstantSpecs::ContainerA::ChildA::CSL_CONST301 = :const301_5
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CSL_CONST301).should == [__FILE__, __LINE__ - 1]
+    ensure
+      ConstantSpecs::ClassA.send(:remove_const, :CSL_CONST301)
+      ConstantSpecs::ModuleA.send(:remove_const, :CSL_CONST301)
+      ConstantSpecs::ParentA.send(:remove_const, :CSL_CONST301)
+      ConstantSpecs::ContainerA::ChildA.send(:remove_const, :CSL_CONST301)
+    end
+
+    it "searches a path in a module included in the immediate class before the superclass" do
+      ConstantSpecs::ParentB::CSL_CONST302 = :const302_1
+      ConstantSpecs::ModuleF::CSL_CONST302 = :const302_2
+      ConstantSpecs::ContainerB::ChildB.const_source_location(:CSL_CONST302).should == [__FILE__, __LINE__ - 1]
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CSL_CONST302)
+      ConstantSpecs::ModuleF.send(:remove_const, :CSL_CONST302)
+    end
+
+    it "searches a path in the superclass before a module included in the superclass" do
+      ConstantSpecs::ModuleE::CSL_CONST303 = :const303_1
+      ConstantSpecs::ParentB::CSL_CONST303 = :const303_2
+      ConstantSpecs::ContainerB::ChildB.const_source_location(:CSL_CONST303).should == [__FILE__, __LINE__ - 1]
+    ensure
+      ConstantSpecs::ModuleE.send(:remove_const, :CSL_CONST303)
+      ConstantSpecs::ParentB.send(:remove_const, :CSL_CONST303)
+    end
+
+    it "searches a path in a module included in the superclass" do
+      ConstantSpecs::ModuleA::CSL_CONST304 = :const304_1
+      ConstantSpecs::ModuleE::CSL_CONST304 = :const304_2
+      ConstantSpecs::ContainerB::ChildB.const_source_location(:CSL_CONST304).should == [__FILE__, __LINE__ - 1]
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CSL_CONST304)
+      ConstantSpecs::ModuleE.send(:remove_const, :CSL_CONST304)
+    end
+
+    it "searches a path in the superclass chain" do
+      ConstantSpecs::ModuleA::CSL_CONST305 = :const305
+      ConstantSpecs::ContainerB::ChildB.const_source_location(:CSL_CONST305).should == [__FILE__, __LINE__ - 1]
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CSL_CONST305)
+    end
+
+    it "returns path to a toplevel constant when the receiver is a Class" do
+      Object::CSL_CONST306 = :const306
+      ConstantSpecs::ContainerB::ChildB.const_source_location(:CSL_CONST306).should == [__FILE__, __LINE__ - 1]
+    ensure
+      Object.send(:remove_const, :CSL_CONST306)
+    end
+
+    it "returns path to a toplevel constant when the receiver is a Module" do
+      Object::CSL_CONST308 = :const308
+      ConstantSpecs.const_source_location(:CSL_CONST308).should == [__FILE__, __LINE__ - 1]
+      ConstantSpecs::ModuleA.const_source_location(:CSL_CONST308).should == [__FILE__, __LINE__ - 2]
+    ensure
+      Object.send(:remove_const, :CSL_CONST308)
+    end
+
+    it "returns path to the updated value of a constant" do
+      ConstantSpecs::ClassB::CSL_CONST309 = :const309_1
+      ConstantSpecs::ClassB.const_source_location(:CSL_CONST309).should == [__FILE__, __LINE__ - 1]
+
+      -> {
+        ConstantSpecs::ClassB::CSL_CONST309 = :const309_2
+      }.should complain(/already initialized constant/)
+      ConstantSpecs::ClassB.const_source_location(:CSL_CONST309).should == [__FILE__, __LINE__ - 2]
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CSL_CONST309)
+    end
+  end
+
+  describe "with statically assigned constants" do
+    it "works for the module and class keywords" do
+      ConstantSpecs.const_source_location(:ModuleB).should == [@constants_fixture_path, ConstantSpecs::ModuleB::LINE]
+      ConstantSpecs.const_source_location(:ClassA).should == [@constants_fixture_path, ConstantSpecs::ClassA::LINE]
+    end
+
+    it "searches location path the immediate class or module first" do
+      ConstantSpecs::ClassA.const_source_location(:CS_CONST10).should == [@constants_fixture_path, ConstantSpecs::ClassA::CS_CONST10_LINE]
+      ConstantSpecs::ModuleA.const_source_location(:CS_CONST10).should == [@constants_fixture_path, ConstantSpecs::ModuleA::CS_CONST10_LINE]
+      ConstantSpecs::ParentA.const_source_location(:CS_CONST10).should == [@constants_fixture_path, ConstantSpecs::ParentA::CS_CONST10_LINE]
+      ConstantSpecs::ContainerA.const_source_location(:CS_CONST10).should == [@constants_fixture_path, ConstantSpecs::ContainerA::CS_CONST10_LINE]
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST10).should == [@constants_fixture_path, ConstantSpecs::ContainerA::ChildA::CS_CONST10_LINE]
+    end
+
+    it "searches location path a module included in the immediate class before the superclass" do
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST15).should == [@constants_fixture_path, ConstantSpecs::ModuleC::CS_CONST15_LINE]
+    end
+
+    it "searches location path the superclass before a module included in the superclass" do
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST11).should == [@constants_fixture_path, ConstantSpecs::ParentA::CS_CONST11_LINE]
+    end
+
+    it "searches location path a module included in the superclass" do
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST12).should == [@constants_fixture_path, ConstantSpecs::ModuleB::CS_CONST12_LINE]
+    end
+
+    it "searches location path the superclass chain" do
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST13).should == [@constants_fixture_path, ConstantSpecs::ModuleA::CS_CONST13_LINE]
+    end
+
+    it "returns location path a toplevel constant when the receiver is a Class" do
+      ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST1).should == [@constants_fixture_path, CS_CONST1_LINE]
+    end
+
+    it "returns location path a toplevel constant when the receiver is a Module" do
+      ConstantSpecs.const_source_location(:CS_CONST1).should == [@constants_fixture_path, CS_CONST1_LINE]
+      ConstantSpecs::ModuleA.const_source_location(:CS_CONST1).should == [@constants_fixture_path, CS_CONST1_LINE]
+    end
+  end
+
+  it "return empty path if constant defined in C code" do
+    Object.const_source_location(:String).should == []
+  end
+
+  it "accepts a String or Symbol name" do
+    Object.const_source_location(:CS_CONST1).should == [@constants_fixture_path, CS_CONST1_LINE]
+    Object.const_source_location("CS_CONST1").should == [@constants_fixture_path, CS_CONST1_LINE]
+  end
+
+  it "returns nil if no constant is defined in the search path" do
+    ConstantSpecs.const_source_location(:CS_CONSTX).should == nil
+  end
+
+  it "raises a NameError if the name does not start with a capital letter" do
+    -> { ConstantSpecs.const_source_location "name" }.should.raise(NameError)
+  end
+
+  it "raises a NameError if the name starts with a non-alphabetic character" do
+    -> { ConstantSpecs.const_source_location "__CONSTX__" }.should.raise(NameError)
+    -> { ConstantSpecs.const_source_location "@CS_CONST1" }.should.raise(NameError)
+    -> { ConstantSpecs.const_source_location "!CS_CONST1" }.should.raise(NameError)
+  end
+
+  it "raises a NameError if the name contains non-alphabetic characters except '_'" do
+    Object.const_source_location("CS_CONST1").should == [@constants_fixture_path, CS_CONST1_LINE]
+    -> { ConstantSpecs.const_source_location "CS_CONST1=" }.should.raise(NameError)
+    -> { ConstantSpecs.const_source_location "CS_CONST1?" }.should.raise(NameError)
+  end
+
+  it "calls #to_str to convert the given name to a String" do
+    name = mock("ClassA")
+    name.should_receive(:to_str).and_return("ClassA")
+    ConstantSpecs.const_source_location(name).should == [@constants_fixture_path, ConstantSpecs::ClassA::LINE]
+  end
+
+  it "raises a TypeError if conversion to a String by calling #to_str fails" do
+    name = mock('123')
+    -> { ConstantSpecs.const_source_location(name) }.should.raise(TypeError)
+
+    name.should_receive(:to_str).and_return(123)
+    -> { ConstantSpecs.const_source_location(name) }.should.raise(TypeError)
+  end
+
+  it "does not search the singleton class of a Class or Module" do
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST14).should == nil
+    ConstantSpecs.const_source_location(:CS_CONST14).should == nil
+  end
+
+  it "does not search the containing scope" do
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST20).should == [@constants_fixture_path, ConstantSpecs::ParentA::CS_CONST20_LINE]
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST5) == nil
+  end
+
+  it "returns nil if the constant is defined in the receiver's superclass and the inherit flag is false" do
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST4, false).should == nil
+  end
+
+  it "searches into the receiver superclasses if the inherit flag is true" do
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST4, true).should == [@constants_fixture_path, ConstantSpecs::ParentA::CS_CONST4_LINE]
+  end
+
+  it "returns nil when the receiver is a Module, the constant is defined at toplevel and the inherit flag is false" do
+    ConstantSpecs::ModuleA.const_source_location(:CS_CONST1, false).should == nil
+  end
+
+  it "returns nil when the receiver is a Class, the constant is defined at toplevel and the inherit flag is false" do
+    ConstantSpecs::ContainerA::ChildA.const_source_location(:CS_CONST1, false).should == nil
+  end
+
+  it "accepts a toplevel scope qualifier" do
+    ConstantSpecs.const_source_location("::CS_CONST1").should == [@constants_fixture_path, CS_CONST1_LINE]
+  end
+
+  it "accepts a scoped constant name" do
+    ConstantSpecs.const_source_location("ClassA::CS_CONST10").should == [@constants_fixture_path, ConstantSpecs::ClassA::CS_CONST10_LINE]
+  end
+
+  it "returns updated location from const_set" do
+    mod = Module.new
+    const_line = __LINE__ + 1
+    mod.const_set :Foo, 1
+    mod.const_source_location(:Foo).should == [__FILE__, const_line]
+  end
+
+  it "raises a NameError if the name includes two successive scope separators" do
+    -> { ConstantSpecs.const_source_location("ClassA::::CS_CONST10") }.should.raise(NameError)
+  end
+
+  it "raises a NameError if only '::' is passed" do
+    -> { ConstantSpecs.const_source_location("::") }.should.raise(NameError)
+  end
+
+  it "raises a NameError if a Symbol has a toplevel scope qualifier" do
+    -> { ConstantSpecs.const_source_location(:'::CS_CONST1') }.should.raise(NameError)
+  end
+
+  it "raises a NameError if a Symbol is a scoped constant name" do
+    -> { ConstantSpecs.const_source_location(:'ClassA::CS_CONST10') }.should.raise(NameError)
+  end
+
+  it "does search private constants path" do
+    ConstantSpecs.const_source_location(:CS_PRIVATE).should == [@constants_fixture_path, ConstantSpecs::CS_PRIVATE_LINE]
+  end
+
+  it "works for eval with a given line" do
+    c = Class.new do
+      eval('self::C = 1', nil, "foo", 100)
+    end
+    c.const_source_location(:C).should == ["foo", 100]
+  end
+
+  context 'autoload' do
+    before :all do
+      ConstantSpecs.autoload :CSL_CONST1, "#{__dir__}/notexisting.rb"
+      @line = __LINE__ - 1
+    end
+
+    before :each do
+      @loaded_features = $".dup
+    end
+
+    after :each do
+      $".replace @loaded_features
+    end
+
+    it 'returns the autoload location while not resolved' do
+      ConstantSpecs.const_source_location('CSL_CONST1').should == [__FILE__, @line]
+    end
+
+    it 'returns where the constant was resolved when resolved' do
+      file = fixture(__FILE__, 'autoload_location.rb')
+      ConstantSpecs.autoload :CONST_LOCATION, file
+      line = ConstantSpecs::CONST_LOCATION
+      ConstantSpecs.const_source_location('CONST_LOCATION').should == [file, line]
+    end
+
+    ruby_bug("#20188", ""..."3.4") do
+      it 'returns the real constant location as soon as it is defined' do
+        file = fixture(__FILE__, 'autoload_const_source_location.rb')
+        ConstantSpecs.autoload :ConstSource, file
+        autoload_location = [__FILE__, __LINE__ - 1]
+
+        ConstantSpecs.const_source_location(:ConstSource).should == autoload_location
+        ConstantSpecs::ConstSource::LOCATION.should == ConstantSpecs.const_source_location(:ConstSource)
+        ConstantSpecs::BEFORE_DEFINE_LOCATION.should == autoload_location
+        ConstantSpecs.send :remove_const, :ConstSource
+        ConstantSpecs.send :remove_const, :BEFORE_DEFINE_LOCATION
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/module/constants_spec.rb b/spec/ruby/core/module/constants_spec.rb
index 4538e828dd..f2f12761e3 100644
--- a/spec/ruby/core/module/constants_spec.rb
+++ b/spec/ruby/core/module/constants_spec.rb
@@ -13,12 +13,13 @@ describe "Module.constants" do
 
   it "returns an array of Symbol names" do
     # This in NOT an exhaustive list
-    Module.constants.should include(:Array, :Bignum, :Class, :Comparable, :Dir,
+    Module.constants.to_set.should >= Set[
+                                    :Array, :Class, :Comparable, :Dir,
                                     :Enumerable, :ENV, :Exception, :FalseClass,
-                                    :File, :Fixnum, :Float, :Hash, :Integer, :IO,
+                                    :File, :Float, :Hash, :Integer, :IO,
                                     :Kernel, :Math, :Method, :Module, :NilClass,
                                     :Numeric, :Object, :Range, :Regexp, :String,
-                                    :Symbol, :Thread, :Time, :TrueClass)
+                                    :Symbol, :Thread, :Time, :TrueClass]
   end
 
   it "returns Module's constants when given a parameter" do
@@ -43,37 +44,43 @@ end
 describe "Module#constants" do
   it "returns an array of Symbol names of all constants defined in the module and all included modules" do
     ConstantSpecs::ContainerA.constants.sort.should == [
-      :CS_CONST10, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
+      :CS_CONST10, :CS_CONST10_LINE, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
     ]
   end
 
   it "returns all constants including inherited when passed true" do
     ConstantSpecs::ContainerA.constants(true).sort.should == [
-      :CS_CONST10, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
+      :CS_CONST10, :CS_CONST10_LINE, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
     ]
   end
 
   it "returns all constants including inherited when passed some object" do
     ConstantSpecs::ContainerA.constants(Object.new).sort.should == [
-      :CS_CONST10, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
+      :CS_CONST10, :CS_CONST10_LINE, :CS_CONST23, :CS_CONST24, :CS_CONST5, :ChildA
     ]
   end
 
   it "doesn't returns inherited constants when passed false" do
     ConstantSpecs::ContainerA.constants(false).sort.should == [
-      :CS_CONST10, :CS_CONST23, :CS_CONST5, :ChildA
+      :CS_CONST10, :CS_CONST10_LINE, :CS_CONST23, :CS_CONST5, :ChildA
     ]
   end
 
   it "doesn't returns inherited constants when passed nil" do
     ConstantSpecs::ContainerA.constants(nil).sort.should == [
-      :CS_CONST10, :CS_CONST23, :CS_CONST5, :ChildA
+      :CS_CONST10, :CS_CONST10_LINE, :CS_CONST23, :CS_CONST5, :ChildA
     ]
   end
 
   it "returns only public constants" do
     ModuleSpecs::PrivConstModule.constants.should == [:PUBLIC_CONSTANT]
   end
+
+  it "returns only constants starting with an uppercase letter" do
+    # e.g. fatal, IO::generic_readable and IO::generic_writable should not be returned by Module#constants
+    Object.constants.each { |c| c[0].should == c[0].upcase }
+    IO.constants.each { |c| c[0].should == c[0].upcase }
+  end
 end
 
 describe "Module#constants" do
@@ -86,6 +93,6 @@ describe "Module#constants" do
   end
 
   it "includes names of constants defined after a module is included" do
-    ConstantSpecs::ContainerA.constants.should include(:CS_CONST251)
+    ConstantSpecs::ContainerA.constants.should.include?(:CS_CONST251)
   end
 end
diff --git a/spec/ruby/core/module/define_method_spec.rb b/spec/ruby/core/module/define_method_spec.rb
index 29394e5b92..f838e2b85f 100644
--- a/spec/ruby/core/module/define_method_spec.rb
+++ b/spec/ruby/core/module/define_method_spec.rb
@@ -12,7 +12,7 @@ describe "passed { |a, b = 1|  } creates a method that" do
   end
 
   it "raises an ArgumentError when passed zero arguments" do
-    -> { @klass.new.m }.should raise_error(ArgumentError)
+    -> { @klass.new.m }.should.raise(ArgumentError)
   end
 
   it "has a default value for b when passed one argument" do
@@ -24,7 +24,7 @@ describe "passed { |a, b = 1|  } creates a method that" do
   end
 
   it "raises an ArgumentError when passed three arguments" do
-    -> { @klass.new.m(1, 2, 3) }.should raise_error(ArgumentError)
+    -> { @klass.new.m(1, 2, 3) }.should.raise(ArgumentError)
   end
 end
 
@@ -47,7 +47,7 @@ describe "Module#define_method when given an UnboundMethod" do
       end
       define_method(:another_test_method, instance_method(:test_method))
     end
-    klass.new.should have_method(:another_test_method)
+    klass.new.should.respond_to?(:another_test_method)
   end
 
   describe "defining a method on a singleton class" do
@@ -83,11 +83,28 @@ describe "Module#define_method when given an UnboundMethod" do
       define_method :piggy, instance_method(:ziggy)
     end
 
-    -> { foo.new.ziggy }.should raise_error(NoMethodError)
+    -> { foo.new.ziggy }.should.raise(NoMethodError)
     foo.new.piggy.should == 'piggy'
   end
 end
 
+describe "Module#define_method" do
+  describe "when the default definee is not the same as the module" do
+    it "sets the visibility of the method to public" do
+      klass = Class.new
+      class << klass
+        private
+        define_method(:meta) do
+          define_method(:foo) { :foo }
+        end
+      end
+
+      klass.send :meta
+      klass.new.foo.should == :foo
+    end
+  end
+end
+
 describe "Module#define_method when name is not a special private name" do
   describe "given an UnboundMethod" do
     describe "and called from the target module" do
@@ -98,8 +115,8 @@ describe "Module#define_method when name is not a special private name" do
           define_method(:baz, ModuleSpecs::EmptyFooMethod)
         end
 
-        klass.should have_public_instance_method(:bar)
-        klass.should have_private_instance_method(:baz)
+        klass.public_instance_methods(false).should.include?(:bar)
+        klass.private_instance_methods(false).should.include?(:baz)
       end
     end
 
@@ -112,9 +129,20 @@ describe "Module#define_method when name is not a special private name" do
           klass.send(:define_method, :baz, ModuleSpecs::EmptyFooMethod)
         end
 
-        klass.should have_public_instance_method(:bar)
-        klass.should have_public_instance_method(:baz)
+        klass.public_instance_methods(false).should.include?(:bar)
+        klass.public_instance_methods(false).should.include?(:baz)
+      end
+    end
+
+    it "sets the method owner for a dynamically added method with a different original owner" do
+      mixin_module = Module.new do
+        def bar; end
       end
+
+      foo = Object.new
+      foo.singleton_class.define_method(:bar, mixin_module.instance_method(:bar))
+
+      foo.method(:bar).owner.should == foo.singleton_class
     end
   end
 
@@ -127,8 +155,8 @@ describe "Module#define_method when name is not a special private name" do
           define_method(:baz) {}
         end
 
-        klass.should have_public_instance_method(:bar)
-        klass.should have_private_instance_method(:baz)
+        klass.public_instance_methods(false).should.include?(:bar)
+        klass.private_instance_methods(false).should.include?(:baz)
       end
     end
 
@@ -141,8 +169,8 @@ describe "Module#define_method when name is not a special private name" do
           klass.send(:define_method, :baz) {}
         end
 
-        klass.should have_public_instance_method(:bar)
-        klass.should have_public_instance_method(:baz)
+        klass.public_instance_methods(false).should.include?(:bar)
+        klass.public_instance_methods(false).should.include?(:baz)
       end
     end
   end
@@ -154,7 +182,7 @@ describe "Module#define_method when name is :initialize" do
       klass = Class.new do
         define_method(:initialize) { }
       end
-      klass.should have_private_instance_method(:initialize)
+      klass.private_instance_methods(false).should.include?(:initialize)
     end
   end
 
@@ -165,7 +193,7 @@ describe "Module#define_method when name is :initialize" do
         end
         define_method(:initialize, instance_method(:test_method))
       end
-      klass.should have_private_instance_method(:initialize)
+      klass.private_instance_methods(false).should.include?(:initialize)
     end
   end
 end
@@ -202,24 +230,61 @@ describe "Module#define_method" do
     o.block_test2.should == o
   end
 
+  it "raises TypeError if name cannot converted to String" do
+    -> {
+      Class.new { define_method(1001, -> {}) }
+    }.should.raise(TypeError, /is not a symbol nor a string/)
+
+    -> {
+      Class.new { define_method([], -> {}) }
+    }.should.raise(TypeError, /is not a symbol nor a string/)
+  end
+
+  it "converts non-String name to String with #to_str" do
+    obj = Object.new
+    def obj.to_str() "foo" end
+
+    new_class = Class.new { define_method(obj, -> { :called }) }
+    new_class.new.foo.should == :called
+  end
+
+  it "raises TypeError when #to_str called on non-String name returns non-String value" do
+    obj = Object.new
+    def obj.to_str() [] end
+
+    -> {
+      Class.new { define_method(obj, -> {}) }
+    }.should raise_consistent_error(TypeError, /can't convert Object into String/)
+  end
+
   it "raises a TypeError when the given method is no Method/Proc" do
     -> {
       Class.new { define_method(:test, "self") }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError, "wrong argument type String (expected Proc/Method/UnboundMethod)")
 
     -> {
       Class.new { define_method(:test, 1234) }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError, "wrong argument type Integer (expected Proc/Method/UnboundMethod)")
 
     -> {
       Class.new { define_method(:test, nil) }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError, "wrong argument type NilClass (expected Proc/Method/UnboundMethod)")
+  end
+
+  it "uses provided Method/Proc even if block is specified" do
+    new_class = Class.new do
+      define_method(:test, -> { :method_is_called }) do
+        :block_is_called
+      end
+    end
+
+    new_class.new.test.should == :method_is_called
   end
 
   it "raises an ArgumentError when no block is given" do
     -> {
       Class.new { define_method(:test) }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "does not use the caller block when no block is given" do
@@ -232,7 +297,7 @@ describe "Module#define_method" do
 
     -> {
       o.define(:foo) { raise "not used" }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "does not change the arity check style of the original proc" do
@@ -242,13 +307,13 @@ describe "Module#define_method" do
     end
 
     obj = DefineMethodSpecClass.new
-    -> { obj.proc_style_test :arg }.should raise_error(ArgumentError)
+    -> { obj.proc_style_test :arg }.should.raise(ArgumentError)
   end
 
-  it "raises a #{frozen_error_class} if frozen" do
+  it "raises a FrozenError if frozen" do
     -> {
       Class.new { freeze; define_method(:foo) {} }
-    }.should raise_error(frozen_error_class)
+    }.should.raise(FrozenError)
   end
 
   it "accepts a Method (still bound)" do
@@ -261,13 +326,13 @@ describe "Module#define_method" do
     o = DefineMethodSpecClass.new
     o.data = :foo
     m = o.method(:inspect_data)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     klass = Class.new(DefineMethodSpecClass)
     klass.send(:define_method,:other_inspect, m)
     c = klass.new
     c.data = :bar
     c.other_inspect.should == "data is bar"
-    ->{o.other_inspect}.should raise_error(NoMethodError)
+    ->{o.other_inspect}.should.raise(NoMethodError)
   end
 
   it "raises a TypeError when a Method from a singleton class is defined on another class" do
@@ -281,7 +346,7 @@ describe "Module#define_method" do
 
     -> {
       Class.new { define_method :bar, m }
-    }.should raise_error(TypeError, /can't bind singleton method to a different class/)
+    }.should.raise(TypeError, /can't bind singleton method to a different class/)
   end
 
   it "raises a TypeError when a Method from one class is defined on an unrelated class" do
@@ -293,7 +358,7 @@ describe "Module#define_method" do
 
     -> {
       Class.new { define_method :bar, m }
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "accepts an UnboundMethod from an attr_accessor method" do
@@ -305,7 +370,7 @@ describe "Module#define_method" do
     o = DefineMethodSpecClass.new
 
     DefineMethodSpecClass.send(:undef_method, :accessor_method)
-    -> { o.accessor_method }.should raise_error(NoMethodError)
+    -> { o.accessor_method }.should.raise(NoMethodError)
 
     DefineMethodSpecClass.send(:define_method, :accessor_method, m)
 
@@ -333,6 +398,14 @@ describe "Module#define_method" do
     object2.other_cool_method.should == "data is foo"
   end
 
+  it "accepts a proc from a Symbol" do
+    symbol_proc = :+.to_proc
+    klass = Class.new do
+      define_method :foo, &symbol_proc
+    end
+    klass.new.foo(1, 2).should == 3
+  end
+
   it "maintains the Proc's scope" do
     class DefineMethodByProcClass
       in_scope = true
@@ -342,7 +415,7 @@ describe "Module#define_method" do
     end
 
     o = DefineMethodByProcClass.new
-    o.proc_test.should be_true
+    o.proc_test.should == true
   end
 
   it "accepts a String method name" do
@@ -355,15 +428,8 @@ describe "Module#define_method" do
     klass.new.string_test.should == "string_test result"
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:define_method)
-    end
-  end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:define_method)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:define_method)
   end
 
   it "returns its symbol" do
@@ -377,7 +443,7 @@ describe "Module#define_method" do
     klass = Class.new {
       define_method :bar, ModuleSpecs::UnboundMethodTest.instance_method(:foo)
     }
-    klass.new.should respond_to(:bar)
+    klass.new.should.respond_to?(:bar)
   end
 
   it "allows an UnboundMethod from a parent class to be defined on a child class" do
@@ -385,7 +451,7 @@ describe "Module#define_method" do
     child = Class.new(parent) {
       define_method :baz, parent.instance_method(:foo)
     }
-    child.new.should respond_to(:baz)
+    child.new.should.respond_to?(:baz)
   end
 
   it "allows an UnboundMethod from a module to be defined on another unrelated module" do
@@ -393,7 +459,7 @@ describe "Module#define_method" do
       define_method :bar, ModuleSpecs::UnboundMethodTest.instance_method(:foo)
     }
     klass = Class.new { include mod }
-    klass.new.should respond_to(:bar)
+    klass.new.should.respond_to?(:bar)
   end
 
 
@@ -409,7 +475,10 @@ describe "Module#define_method" do
       ParentClass = Class.new { define_method(:foo) { :bar } }
       ChildClass = Class.new(ParentClass) { define_method(:foo) { :baz } }
       ParentClass.send :define_method, :foo, ChildClass.instance_method(:foo)
-    }.should raise_error(TypeError, /bind argument must be a subclass of ChildClass/)
+    }.should.raise(TypeError, /bind argument must be a subclass of ChildClass/)
+  ensure
+    Object.send(:remove_const, :ParentClass)
+    Object.send(:remove_const, :ChildClass)
   end
 
   it "raises a TypeError when an UnboundMethod from one class is defined on an unrelated class" do
@@ -417,7 +486,7 @@ describe "Module#define_method" do
       DestinationClass = Class.new {
         define_method :bar, ModuleSpecs::InstanceMeth.instance_method(:foo)
       }
-    }.should raise_error(TypeError, /bind argument must be a subclass of ModuleSpecs::InstanceMeth/)
+    }.should.raise(TypeError, /bind argument must be a subclass of ModuleSpecs::InstanceMeth/)
   end
 
   it "raises a TypeError when an UnboundMethod from a singleton class is defined on another class" do
@@ -431,7 +500,34 @@ describe "Module#define_method" do
 
     -> {
       Class.new { define_method :bar, m }
-    }.should raise_error(TypeError, /can't bind singleton method to a different class/)
+    }.should.raise(TypeError, /can't bind singleton method to a different class/)
+  end
+
+  it "defines a new method with public visibility when a Method passed and the class/module of the context isn't equal to the receiver of #define_method" do
+    c = Class.new do
+      private def foo
+        "public"
+      end
+    end
+
+    object = c.new
+    object.singleton_class.define_method(:bar, object.method(:foo))
+
+    object.bar.should == "public"
+  end
+
+  it "defines the new method according to the scope visibility when a Method passed and the class/module of the context is equal to the receiver of #define_method" do
+    c = Class.new do
+      def foo; end
+    end
+
+    object = c.new
+    object.singleton_class.class_eval do
+      private
+      define_method(:bar, c.new.method(:foo))
+    end
+
+    -> { object.bar }.should.raise(NoMethodError)
   end
 end
 
@@ -448,11 +544,11 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed one argument" do
-      -> { @klass.new.m 1 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1 }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed two arguments" do
-      -> { @klass.new.m 1, 2 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1, 2 }.should.raise(ArgumentError)
     end
   end
 
@@ -468,11 +564,11 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed one argument" do
-      -> { @klass.new.m 1 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1 }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed two arguments" do
-      -> { @klass.new.m 1, 2 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1, 2 }.should.raise(ArgumentError)
     end
   end
 
@@ -484,21 +580,50 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed zero arguments" do
-      -> { @klass.new.m }.should raise_error(ArgumentError)
+      -> { @klass.new.m }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed zero arguments and a block" do
-      -> { @klass.new.m { :computed } }.should raise_error(ArgumentError)
+      -> { @klass.new.m { :computed } }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed two arguments" do
-      -> { @klass.new.m 1, 2 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1, 2 }.should.raise(ArgumentError)
     end
 
     it "receives the value passed as the argument when passed one argument" do
       @klass.new.m(1).should == 1
     end
+  end
+
+  describe "passed { |a,|  } creates a method that" do
+    before :each do
+      @klass = Class.new do
+        define_method(:m) { |a,| a }
+      end
+    end
+
+    it "raises an ArgumentError when passed zero arguments" do
+      -> { @klass.new.m }.should.raise(ArgumentError)
+    end
+
+    it "raises an ArgumentError when passed zero arguments and a block" do
+      -> { @klass.new.m { :computed } }.should.raise(ArgumentError)
+    end
 
+    it "raises an ArgumentError when passed two arguments" do
+      -> { @klass.new.m 1, 2 }.should.raise(ArgumentError)
+    end
+
+    it "receives the value passed as the argument when passed one argument" do
+      @klass.new.m(1).should == 1
+    end
+
+    it "does not destructure the passed argument" do
+      @klass.new.m([1, 2]).should == [1, 2]
+      # for comparison:
+      proc { |a,| a }.call([1, 2]).should == 1
+    end
   end
 
   describe "passed { |*a|  } creates a method that" do
@@ -529,7 +654,7 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed zero arguments" do
-      -> { @klass.new.m }.should raise_error(ArgumentError)
+      -> { @klass.new.m }.should.raise(ArgumentError)
     end
 
     it "returns the value computed by the block when passed one argument" do
@@ -557,19 +682,19 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed zero arguments" do
-      -> { @klass.new.m }.should raise_error(ArgumentError)
+      -> { @klass.new.m }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed one argument" do
-      -> { @klass.new.m 1 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1 }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed one argument and a block" do
-      -> { @klass.new.m(1) { } }.should raise_error(ArgumentError)
+      -> { @klass.new.m(1) { } }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed three arguments" do
-      -> { @klass.new.m 1, 2, 3 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1, 2, 3 }.should.raise(ArgumentError)
     end
   end
 
@@ -581,15 +706,15 @@ describe "Module#define_method" do
     end
 
     it "raises an ArgumentError when passed zero arguments" do
-      -> { @klass.new.m }.should raise_error(ArgumentError)
+      -> { @klass.new.m }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed one argument" do
-      -> { @klass.new.m 1 }.should raise_error(ArgumentError)
+      -> { @klass.new.m 1 }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed one argument and a block" do
-      -> { @klass.new.m(1) { } }.should raise_error(ArgumentError)
+      -> { @klass.new.m(1) { } }.should.raise(ArgumentError)
     end
 
     it "receives an empty array as the third argument when passed two arguments" do
@@ -602,7 +727,7 @@ describe "Module#define_method" do
   end
 end
 
-describe "Method#define_method when passed a Method object" do
+describe "Module#define_method when passed a Method object" do
   before :each do
     @klass = Class.new do
       def m(a, b, *c)
@@ -627,7 +752,7 @@ describe "Method#define_method when passed a Method object" do
   end
 end
 
-describe "Method#define_method when passed an UnboundMethod object" do
+describe "Module#define_method when passed an UnboundMethod object" do
   before :each do
     @klass = Class.new do
       def m(a, b, *c)
@@ -652,7 +777,7 @@ describe "Method#define_method when passed an UnboundMethod object" do
   end
 end
 
-describe "Method#define_method when passed a Proc object" do
+describe "Module#define_method when passed a Proc object" do
   describe "and a method is defined inside" do
     it "defines the nested method in the default definee where the Proc was created" do
       prc = nil
@@ -670,9 +795,52 @@ describe "Method#define_method when passed a Proc object" do
 
       o = c.new
       o.test
-      o.should_not have_method :nested_method_in_proc_for_define_method
+      o.should_not.respond_to? :nested_method_in_proc_for_define_method
 
       t.new.nested_method_in_proc_for_define_method.should == 42
     end
   end
 end
+
+describe "Module#define_method when passed a block" do
+  describe "behaves exactly like a lambda" do
+    it "for return" do
+      Class.new do
+        define_method(:foo) do
+          return 42
+        end
+      end.new.foo.should == 42
+    end
+
+    it "for break" do
+      Class.new do
+        define_method(:foo) do
+          break 42
+        end
+      end.new.foo.should == 42
+    end
+
+    it "for next" do
+      Class.new do
+        define_method(:foo) do
+          next 42
+        end
+      end.new.foo.should == 42
+    end
+
+    it "for redo" do
+      Class.new do
+        result = []
+        define_method(:foo) do
+          if result.empty?
+            result << :first
+            redo
+          else
+            result << :second
+            result
+          end
+        end
+      end.new.foo.should == [:first, :second]
+    end
+  end
+end
diff --git a/spec/ruby/core/module/deprecate_constant_spec.rb b/spec/ruby/core/module/deprecate_constant_spec.rb
index 7bcced981b..597379eb87 100644
--- a/spec/ruby/core/module/deprecate_constant_spec.rb
+++ b/spec/ruby/core/module/deprecate_constant_spec.rb
@@ -9,7 +9,6 @@ describe "Module#deprecate_constant" do
     @module::PRIVATE = @value
     @module.private_constant :PRIVATE
     @module.deprecate_constant :PRIVATE
-    @pattern = /deprecated/
   end
 
   describe "when accessing the deprecated module" do
@@ -19,32 +18,53 @@ describe "Module#deprecate_constant" do
       value = nil
       -> {
         value = @module::PUBLIC1
-      }.should complain(@pattern)
-      value.should equal(@value)
+      }.should complain(/warning: constant .+::PUBLIC1 is deprecated/)
+      value.should.equal?(@value)
 
-      -> { @module::PRIVATE }.should raise_error(NameError)
+      -> { @module::PRIVATE }.should.raise(NameError)
     end
 
     it "warns with a message" do
       @module.deprecate_constant :PUBLIC1
 
-      -> { @module::PUBLIC1 }.should complain(@pattern)
-      -> { @module.const_get :PRIVATE }.should complain(@pattern)
+      -> { @module::PUBLIC1 }.should complain(/warning: constant .+::PUBLIC1 is deprecated/)
+      -> { @module.const_get :PRIVATE }.should complain(/warning: constant .+::PRIVATE is deprecated/)
+    end
+
+    it "does not warn if Warning[:deprecated] is false" do
+      @module.deprecate_constant :PUBLIC1
+
+      deprecated = Warning[:deprecated]
+      begin
+        Warning[:deprecated] = false
+        -> { @module::PUBLIC1 }.should_not complain
+      ensure
+        Warning[:deprecated] = deprecated
+      end
+    end
+  end
+
+  ruby_bug '#20900', ''...'3.4' do
+    describe "when removing the deprecated module" do
+      it "warns with a message" do
+        @module.deprecate_constant :PUBLIC1
+        -> { @module.module_eval {remove_const :PUBLIC1} }.should complain(/warning: constant .+::PUBLIC1 is deprecated/)
+      end
     end
   end
 
   it "accepts multiple symbols and strings as constant names" do
     @module.deprecate_constant "PUBLIC1", :PUBLIC2
 
-    -> { @module::PUBLIC1 }.should complain(@pattern)
-    -> { @module::PUBLIC2 }.should complain(@pattern)
+    -> { @module::PUBLIC1 }.should complain(/warning: constant .+::PUBLIC1 is deprecated/)
+    -> { @module::PUBLIC2 }.should complain(/warning: constant .+::PUBLIC2 is deprecated/)
   end
 
   it "returns self" do
-    @module.deprecate_constant(:PUBLIC1).should equal(@module)
+    @module.deprecate_constant(:PUBLIC1).should.equal?(@module)
   end
 
   it "raises a NameError when given an undefined name" do
-    -> { @module.deprecate_constant :UNDEFINED }.should raise_error(NameError)
+    -> { @module.deprecate_constant :UNDEFINED }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/module/extend_object_spec.rb b/spec/ruby/core/module/extend_object_spec.rb
index bc97a55e7c..b428eb7924 100644
--- a/spec/ruby/core/module/extend_object_spec.rb
+++ b/spec/ruby/core/module/extend_object_spec.rb
@@ -7,18 +7,18 @@ describe "Module#extend_object" do
   end
 
   it "is a private method" do
-    Module.should have_private_instance_method(:extend_object)
+    Module.private_instance_methods(false).should.include?(:extend_object)
   end
 
   describe "on Class" do
     it "is undefined" do
-      Class.should_not have_private_instance_method(:extend_object, true)
+      Class.private_instance_methods(true).should_not.include?(:extend_object)
     end
 
     it "raises a TypeError if calling after rebinded to Class" do
       -> {
         Module.instance_method(:extend_object).bind(Class.new).call Object.new
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 
@@ -42,18 +42,6 @@ describe "Module#extend_object" do
     ScratchPad.recorded.should == :extended
   end
 
-  it "does not copy own tainted status to the given object" do
-    other = Object.new
-    Module.new.taint.send :extend_object, other
-    other.tainted?.should be_false
-  end
-
-  it "does not copy own untrusted status to the given object" do
-    other = Object.new
-    Module.new.untrust.send :extend_object, other
-    other.untrusted?.should be_false
-  end
-
   describe "when given a frozen object" do
     before :each do
       @receiver = Module.new
@@ -61,8 +49,8 @@ describe "Module#extend_object" do
     end
 
     it "raises a RuntimeError before extending the object" do
-      -> { @receiver.send(:extend_object, @object) }.should raise_error(RuntimeError)
-      @object.should_not be_kind_of(@receiver)
+      -> { @receiver.send(:extend_object, @object) }.should.raise(RuntimeError)
+      @object.should_not.is_a?(@receiver)
     end
   end
 end
diff --git a/spec/ruby/core/module/extended_spec.rb b/spec/ruby/core/module/extended_spec.rb
index c6300ffa0b..a4ec5a4ba7 100644
--- a/spec/ruby/core/module/extended_spec.rb
+++ b/spec/ruby/core/module/extended_spec.rb
@@ -39,6 +39,6 @@ describe "Module#extended" do
   end
 
   it "is private in its default implementation" do
-    Module.new.private_methods.should include(:extended)
+    Module.new.private_methods.should.include?(:extended)
   end
 end
diff --git a/spec/ruby/core/module/fixtures/autoload_const_source_location.rb b/spec/ruby/core/module/fixtures/autoload_const_source_location.rb
new file mode 100644
index 0000000000..ee0e5a689f
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_const_source_location.rb
@@ -0,0 +1,6 @@
+module ConstantSpecs
+  BEFORE_DEFINE_LOCATION = const_source_location(:ConstSource)
+  module ConstSource
+    LOCATION = Object.const_source_location(name)
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/autoload_during_autoload_after_define.rb b/spec/ruby/core/module/fixtures/autoload_during_autoload_after_define.rb
new file mode 100644
index 0000000000..a9d886dfd6
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_during_autoload_after_define.rb
@@ -0,0 +1,6 @@
+module ModuleSpecs::Autoload
+  class DuringAutoloadAfterDefine
+    block = ScratchPad.recorded
+    ScratchPad.record(block.call)
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/autoload_during_require_current_file.rb b/spec/ruby/core/module/fixtures/autoload_during_require_current_file.rb
new file mode 100644
index 0000000000..5aa8595065
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_during_require_current_file.rb
@@ -0,0 +1,5 @@
+module ModuleSpecs::Autoload
+  autoload(:AutoloadCurrentFile, __FILE__)
+
+  ScratchPad.record autoload?(:AutoloadCurrentFile)
+end
diff --git a/spec/ruby/core/module/fixtures/autoload_location.rb b/spec/ruby/core/module/fixtures/autoload_location.rb
new file mode 100644
index 0000000000..318851b2df
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_location.rb
@@ -0,0 +1,3 @@
+module ConstantSpecs
+  CONST_LOCATION = __LINE__
+end
diff --git a/spec/ruby/core/module/fixtures/autoload_relative_a.rb b/spec/ruby/core/module/fixtures/autoload_relative_a.rb
new file mode 100644
index 0000000000..494181adc2
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_relative_a.rb
@@ -0,0 +1,9 @@
+module ModuleSpecs
+  module Autoload
+    class AutoloadRelativeA
+    end
+
+    class AutoloadRelativeB
+    end
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/autoload_required_directly_no_constant.rb b/spec/ruby/core/module/fixtures/autoload_required_directly_no_constant.rb
new file mode 100644
index 0000000000..25e08c1129
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_required_directly_no_constant.rb
@@ -0,0 +1,2 @@
+block = ScratchPad.recorded
+ScratchPad.record(block.call)
diff --git a/spec/ruby/core/module/fixtures/autoload_self_during_require.rb b/spec/ruby/core/module/fixtures/autoload_self_during_require.rb
new file mode 100644
index 0000000000..f4a514a807
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_self_during_require.rb
@@ -0,0 +1,5 @@
+module ModuleSpecs::Autoload
+  autoload :AutoloadSelfDuringRequire, __FILE__
+  class AutoloadSelfDuringRequire
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/classes.rb b/spec/ruby/core/module/fixtures/classes.rb
index ef70eaf9cf..964f64c593 100644
--- a/spec/ruby/core/module/fixtures/classes.rb
+++ b/spec/ruby/core/module/fixtures/classes.rb
@@ -1,11 +1,14 @@
 module ModuleSpecs
   def self.without_test_modules(modules)
-    ignore = %w[MSpecRSpecAdapter PP::ObjectMixin ModuleSpecs::IncludedInObject MainSpecs::Module ConstantSpecs::ModuleA]
+    ignore = %w[MSpecRSpecAdapter PP::ObjectMixin MainSpecs::Module ConstantSpecs::ModuleA]
     modules.reject { |k| ignore.include?(k.name) }
   end
 
   CONST = :plain_constant
 
+  class NamedClass
+  end
+
   module PrivConstModule
     PRIVATE_CONSTANT = 1
     private_constant :PRIVATE_CONSTANT
@@ -39,6 +42,14 @@ module ModuleSpecs
   class LookupChild < Lookup
   end
 
+  module ModuleWithPrepend
+    prepend LookupMod
+  end
+
+  class WithPrependedModule
+    include ModuleWithPrepend
+  end
+
   class Parent
     # For private_class_method spec
     def self.private_method; end
@@ -349,6 +360,10 @@ module ModuleSpecs
     end
   end
 
+  class SubCVars < CVars
+    @@sub = :sub
+  end
+
   module MVars
     @@mvar = :mvar
   end
@@ -373,6 +388,7 @@ module ModuleSpecs
   # empty modules
   module M1; end
   module M2; end
+  module M3; end
 
   module Autoload
     def self.use_ex1
@@ -580,6 +596,32 @@ module ModuleSpecs
     private :foo
   end
   EmptyFooMethod = m.instance_method(:foo)
+
+  # for undefined_instance_methods spec
+  module UndefinedInstanceMethods
+    module Super
+      def super_included_method; end
+    end
+
+    class Parent
+      def undefed_method; end
+      undef_method :undefed_method
+
+      def parent_method; end
+      def another_parent_method; end
+    end
+
+    class Child < Parent
+      include Super
+
+      undef_method :parent_method
+      undef_method :another_parent_method
+    end
+
+    class Grandchild < Child
+      undef_method :super_included_method
+    end
+  end
 end
 
 class Object
diff --git a/spec/ruby/core/module/fixtures/const_added.rb b/spec/ruby/core/module/fixtures/const_added.rb
new file mode 100644
index 0000000000..0f5baad65d
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/const_added.rb
@@ -0,0 +1,4 @@
+module ModuleSpecs
+  module ConstAddedSpecs
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/module.rb b/spec/ruby/core/module/fixtures/module.rb
index 9050a272ec..34543ca2b4 100644
--- a/spec/ruby/core/module/fixtures/module.rb
+++ b/spec/ruby/core/module/fixtures/module.rb
@@ -1,4 +1,8 @@
 module ModuleSpecs
   module Anonymous
+    module Child
+    end
+
+    SameChild = Child
   end
 end
diff --git a/spec/ruby/core/module/fixtures/multi/foo.rb b/spec/ruby/core/module/fixtures/multi/foo.rb
new file mode 100644
index 0000000000..549996f08f
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/multi/foo.rb
@@ -0,0 +1,6 @@
+module ModuleSpecs::Autoload
+  module Foo
+    autoload :Bar, 'foo/bar_baz'
+    autoload :Baz, 'foo/bar_baz'
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/multi/foo/bar_baz.rb b/spec/ruby/core/module/fixtures/multi/foo/bar_baz.rb
new file mode 100644
index 0000000000..53d3849e1f
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/multi/foo/bar_baz.rb
@@ -0,0 +1,11 @@
+require 'foo'
+
+module ModuleSpecs::Autoload
+  module Foo
+    class Bar
+    end
+
+    class Baz
+    end
+  end
+end
diff --git a/spec/ruby/core/module/fixtures/name.rb b/spec/ruby/core/module/fixtures/name.rb
index fb9e66c309..25c74d3944 100644
--- a/spec/ruby/core/module/fixtures/name.rb
+++ b/spec/ruby/core/module/fixtures/name.rb
@@ -7,4 +7,7 @@ module ModuleSpecs
       Cß.name
     end
   end
+
+  module NameSpecs
+  end
 end
diff --git a/spec/ruby/core/module/fixtures/refine.rb b/spec/ruby/core/module/fixtures/refine.rb
index 46975361dd..e8215aa640 100644
--- a/spec/ruby/core/module/fixtures/refine.rb
+++ b/spec/ruby/core/module/fixtures/refine.rb
@@ -3,6 +3,10 @@ module ModuleSpecs
     def foo; "foo" end
   end
 
+  class ClassWithSuperFoo
+    def foo; [:C] end
+  end
+
   module PrependedModule
     def foo; "foo from prepended module"; end
   end
@@ -10,4 +14,12 @@ module ModuleSpecs
   module IncludedModule
     def foo; "foo from included module"; end
   end
+
+  def self.build_refined_class(for_super: false)
+    if for_super
+      Class.new(ClassWithSuperFoo)
+    else
+      Class.new(ClassWithFoo)
+    end
+  end
 end
diff --git a/spec/ruby/core/module/fixtures/set_temporary_name.rb b/spec/ruby/core/module/fixtures/set_temporary_name.rb
new file mode 100644
index 0000000000..901b3b94d1
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/set_temporary_name.rb
@@ -0,0 +1,4 @@
+module ModuleSpecs
+  module SetTemporaryNameSpec
+  end
+end
diff --git a/spec/ruby/core/module/gt_spec.rb b/spec/ruby/core/module/gt_spec.rb
index b8a73c9ff9..04cdd90efb 100644
--- a/spec/ruby/core/module/gt_spec.rb
+++ b/spec/ruby/core/module/gt_spec.rb
@@ -3,10 +3,10 @@ require_relative 'fixtures/classes'
 
 describe "Module#>" do
   it "returns false if self is a subclass of or includes the given module" do
-    (ModuleSpecs::Child > ModuleSpecs::Parent).should be_false
-    (ModuleSpecs::Child > ModuleSpecs::Basic).should be_false
-    (ModuleSpecs::Child > ModuleSpecs::Super).should be_false
-    (ModuleSpecs::Super > ModuleSpecs::Basic).should be_false
+    (ModuleSpecs::Child > ModuleSpecs::Parent).should == false
+    (ModuleSpecs::Child > ModuleSpecs::Basic).should == false
+    (ModuleSpecs::Child > ModuleSpecs::Super).should == false
+    (ModuleSpecs::Super > ModuleSpecs::Basic).should == false
   end
 
   it "returns true if self is a superclass of or included by the given module" do
@@ -31,6 +31,6 @@ describe "Module#>" do
   end
 
   it "raises a TypeError if the argument is not a class/module" do
-    -> { ModuleSpecs::Parent > mock('x') }.should raise_error(TypeError)
+    -> { ModuleSpecs::Parent > mock('x') }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/gte_spec.rb b/spec/ruby/core/module/gte_spec.rb
index 18c60ba586..b19fc9fac3 100644
--- a/spec/ruby/core/module/gte_spec.rb
+++ b/spec/ruby/core/module/gte_spec.rb
@@ -28,6 +28,6 @@ describe "Module#>=" do
   end
 
   it "raises a TypeError if the argument is not a class/module" do
-    -> { ModuleSpecs::Parent >= mock('x') }.should raise_error(TypeError)
+    -> { ModuleSpecs::Parent >= mock('x') }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/include_spec.rb b/spec/ruby/core/module/include_spec.rb
index e7f99a5981..b6201550e4 100644
--- a/spec/ruby/core/module/include_spec.rb
+++ b/spec/ruby/core/module/include_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#include" do
   it "is a public method" do
-    Module.should have_public_instance_method(:include, false)
+    Module.public_instance_methods(false).should.include?(:include)
   end
 
   it "calls #append_features(self) in reversed order on each module" do
@@ -33,24 +33,40 @@ describe "Module#include" do
   end
 
   it "adds all ancestor modules when a previously included module is included again" do
-    ModuleSpecs::MultipleIncludes.ancestors.should include(ModuleSpecs::MA, ModuleSpecs::MB)
+    ModuleSpecs::MultipleIncludes.ancestors.to_set.should >= Set[ModuleSpecs::MA, ModuleSpecs::MB]
     ModuleSpecs::MB.include(ModuleSpecs::MC)
     ModuleSpecs::MultipleIncludes.include(ModuleSpecs::MB)
-    ModuleSpecs::MultipleIncludes.ancestors.should include(ModuleSpecs::MA, ModuleSpecs::MB, ModuleSpecs::MC)
+    ModuleSpecs::MultipleIncludes.ancestors.to_set.should >= Set[ModuleSpecs::MA, ModuleSpecs::MB, ModuleSpecs::MC]
   end
 
   it "raises a TypeError when the argument is not a Module" do
-    -> { ModuleSpecs::Basic.include(Class.new) }.should raise_error(TypeError)
+    -> { ModuleSpecs::Basic.include(Class.new) }.should.raise(TypeError)
   end
 
   it "does not raise a TypeError when the argument is an instance of a subclass of Module" do
-    -> { ModuleSpecs::SubclassSpec.include(ModuleSpecs::Subclass.new) }.should_not raise_error(TypeError)
+    class ModuleSpecs::SubclassSpec::AClass
+    end
+    -> { ModuleSpecs::SubclassSpec::AClass.include(ModuleSpecs::Subclass.new) }.should_not.raise(TypeError)
+  ensure
+    ModuleSpecs::SubclassSpec.send(:remove_const, :AClass)
+  end
+
+  it "raises a TypeError when the argument is a refinement" do
+    refinement = nil
+
+    Module.new do
+      refine String do
+        refinement = self
+      end
+    end
+
+    -> { ModuleSpecs::Basic.include(refinement) }.should.raise(TypeError, "Cannot include refinement")
   end
 
   it "imports constants to modules and classes" do
-    ModuleSpecs::A.constants.should include(:CONSTANT_A)
-    ModuleSpecs::B.constants.should include(:CONSTANT_A, :CONSTANT_B)
-    ModuleSpecs::C.constants.should include(:CONSTANT_A, :CONSTANT_B)
+    ModuleSpecs::A.constants.should.include?(:CONSTANT_A)
+    ModuleSpecs::B.constants.to_set.should >= Set[:CONSTANT_A, :CONSTANT_B]
+    ModuleSpecs::C.constants.to_set.should >= Set[:CONSTANT_A, :CONSTANT_B]
   end
 
   it "shadows constants from ancestors" do
@@ -68,9 +84,9 @@ describe "Module#include" do
   end
 
   it "imports instance methods to modules and classes" do
-    ModuleSpecs::A.instance_methods.should include(:ma)
-    ModuleSpecs::B.instance_methods.should include(:ma,:mb)
-    ModuleSpecs::C.instance_methods.should include(:ma,:mb)
+    ModuleSpecs::A.instance_methods.should.include?(:ma)
+    ModuleSpecs::B.instance_methods.to_set.should >= Set[:ma,:mb]
+    ModuleSpecs::C.instance_methods.to_set.should >= Set[:ma,:mb]
   end
 
   it "does not import methods to modules and classes" do
@@ -104,9 +120,9 @@ describe "Module#include" do
       class A; include M; end
       class B < A; include M; end
 
-      all = [A,B,M]
+      all = [A, B, M]
 
-      (B.ancestors & all).should == [B, A, M]
+      (B.ancestors.filter { |a| all.include?(a) }).should == [B, A, M]
     end
   end
 
@@ -130,7 +146,7 @@ describe "Module#include" do
 
       anc = B.ancestors
       [B, U, V, W, A, X].each do |i|
-        anc.include?(i).should be_true
+        anc.include?(i).should == true
       end
 
       class B; include V; end
@@ -138,7 +154,7 @@ describe "Module#include" do
       # the only new module is Y, it is added after U since it follows U in V mixin list:
       anc = B.ancestors
       [B, U, Y, V, W, A, X].each do |i|
-        anc.include?(i).should be_true
+        anc.include?(i).should == true
       end
     end
   end
@@ -162,7 +178,7 @@ describe "Module#include" do
       module ModuleSpecs::M
         include ModuleSpecs::M
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "doesn't accept no-arguments" do
@@ -170,7 +186,7 @@ describe "Module#include" do
       Module.new do
         include
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "returns the class it's included into" do
@@ -234,6 +250,360 @@ describe "Module#include" do
       remove_const :C
     end
   end
+
+  it "updates the method when an included module is updated" do
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+
+    m_module = Module.new
+
+    b_class = Class.new(a_class) do
+      include m_module
+    end
+
+    b = b_class.new
+
+    foo = -> { b.foo }
+
+    foo.call.should == 'a'
+
+    m_module.module_eval do
+      def foo
+        'm'
+      end
+    end
+
+    foo.call.should == 'm'
+  end
+
+
+  it "updates the method when a module included after a call is later updated" do
+    m_module = Module.new
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+    b_class = Class.new(a_class)
+    b = b_class.new
+    foo = -> { b.foo }
+    foo.call.should == 'a'
+
+    b_class.include m_module
+    foo.call.should == 'a'
+
+    m_module.module_eval do
+      def foo
+        "m"
+      end
+    end
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when a nested included module is updated" do
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+
+    n_module = Module.new
+
+    m_module = Module.new  do
+      include n_module
+    end
+
+    b_class = Class.new(a_class) do
+      include m_module
+    end
+
+    b = b_class.new
+
+    foo = -> { b.foo }
+
+    foo.call.should == 'a'
+
+    n_module.module_eval do
+      def foo
+        'n'
+      end
+    end
+
+    foo.call.should == 'n'
+  end
+
+  it "updates the method when a new module is included" do
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+
+    m_module = Module.new do
+      def foo
+        'm'
+      end
+    end
+
+    b_class = Class.new(a_class)
+    b = b_class.new
+
+    foo = -> { b.foo }
+
+    foo.call.should == 'a'
+
+    b_class.class_eval do
+      include m_module
+    end
+
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when a new module with nested module is included" do
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+
+    n_module = Module.new do
+      def foo
+        'n'
+      end
+    end
+
+    m_module = Module.new  do
+      include n_module
+    end
+
+    b_class = Class.new(a_class)
+    b = b_class.new
+
+    foo = -> { b.foo }
+
+    foo.call.should == 'a'
+
+    b_class.class_eval do
+      include m_module
+    end
+
+    foo.call.should == 'n'
+  end
+
+  it "updates the constant when an included module is updated" do
+    module ModuleSpecs::ConstUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module M
+      end
+
+      module B
+        include A
+        include M
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdated)
+  end
+
+  it "updates the constant when a module included after a call is later updated" do
+    module ModuleSpecs::ConstLaterUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      module M
+      end
+      B.include M
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstLaterUpdated)
+  end
+
+  it "updates the constant when a module included in another module after a call is later updated" do
+    module ModuleSpecs::ConstModuleLaterUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      module M
+      end
+      B.include M
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstModuleLaterUpdated)
+  end
+
+  it "updates the constant when a nested included module is updated" do
+    module ModuleSpecs::ConstUpdatedNestedIncludeUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module N
+      end
+
+      module M
+        include N
+      end
+
+      module B
+        include A
+        include M
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      N.const_set(:FOO, 'n')
+      B.foo.should == 'n'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedNestedIncludeUpdated)
+  end
+
+  it "updates the constant when a new module is included" do
+    module ModuleSpecs::ConstUpdatedNewInclude
+      module A
+        FOO = 'a'
+      end
+
+      module M
+        FOO = 'm'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      B.include(M)
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedNewInclude)
+  end
+
+  it "updates the constant when a new module with nested module is included" do
+    module ModuleSpecs::ConstUpdatedNestedIncluded
+      module A
+        FOO = 'a'
+      end
+
+      module N
+        FOO = 'n'
+      end
+
+      module M
+        include N
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      B.include M
+      B.foo.should == 'n'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedNestedIncluded)
+  end
+
+  it "overrides a previous super method call" do
+    c1 = Class.new do
+      def foo
+        [:c1]
+      end
+    end
+    c2 = Class.new(c1) do
+      def foo
+        [:c2] + super
+      end
+    end
+    c2.new.foo.should == [:c2, :c1]
+    m = Module.new do
+      def foo
+        [:m1]
+      end
+    end
+    c2.include(m)
+    c2.new.foo.should == [:c2, :m1]
+  end
+
+  it "update a module when a nested module is updated and includes a module on its own" do
+    m1 = Module.new
+    m2 = Module.new do
+      def m2; [:m2]; end
+    end
+    m3 = Module.new do
+      def m3; [:m3]; end
+    end
+    m4 = Module.new do
+      def m4; [:m4]; end
+    end
+    c = Class.new
+
+    c.include(m1)
+    m1.include(m2)
+    m2.include(m3)
+    m3.include(m4)
+
+    c.new.m2.should == [:m2]
+    c.new.m3.should == [:m3]
+    c.new.m4.should == [:m4]
+  end
 end
 
 describe "Module#include?" do
@@ -252,7 +622,7 @@ describe "Module#include?" do
   end
 
   it "raises a TypeError when no module was given" do
-    -> { ModuleSpecs::Child.include?("Test") }.should raise_error(TypeError)
-    -> { ModuleSpecs::Child.include?(ModuleSpecs::Parent) }.should raise_error(TypeError)
+    -> { ModuleSpecs::Child.include?("Test") }.should.raise(TypeError)
+    -> { ModuleSpecs::Child.include?(ModuleSpecs::Parent) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/included_modules_spec.rb b/spec/ruby/core/module/included_modules_spec.rb
index 40e20953f4..e22ee5e6cf 100644
--- a/spec/ruby/core/module/included_modules_spec.rb
+++ b/spec/ruby/core/module/included_modules_spec.rb
@@ -4,9 +4,11 @@ require_relative 'fixtures/classes'
 describe "Module#included_modules" do
   it "returns a list of modules included in self" do
     ModuleSpecs.included_modules.should == []
-    ModuleSpecs::Child.included_modules.should include(ModuleSpecs::Super, ModuleSpecs::Basic, Kernel)
-    ModuleSpecs::Parent.included_modules.should include(Kernel)
+
+    ModuleSpecs::Child.included_modules.to_set.should >= Set[ModuleSpecs::Super, ModuleSpecs::Basic, Kernel]
+    ModuleSpecs::Parent.included_modules.should.include?(Kernel)
     ModuleSpecs::Basic.included_modules.should == []
-    ModuleSpecs::Super.included_modules.should include(ModuleSpecs::Basic)
+    ModuleSpecs::Super.included_modules.should.include?(ModuleSpecs::Basic)
+    ModuleSpecs::WithPrependedModule.included_modules.should.include?(ModuleSpecs::ModuleWithPrepend)
   end
 end
diff --git a/spec/ruby/core/module/included_spec.rb b/spec/ruby/core/module/included_spec.rb
index f8dbad1d31..d8a6c3f839 100644
--- a/spec/ruby/core/module/included_spec.rb
+++ b/spec/ruby/core/module/included_spec.rb
@@ -34,11 +34,11 @@ describe "Module#included" do
   end
 
   it "is private in its default implementation" do
-    Module.should have_private_instance_method(:included)
+    Module.private_instance_methods(false).should.include?(:included)
   end
 
   it "works with super using a singleton class" do
     ModuleSpecs::SingletonOnModuleCase::Bar.include ModuleSpecs::SingletonOnModuleCase::Foo
-    ModuleSpecs::SingletonOnModuleCase::Bar.included_called?.should == true
+    ModuleSpecs::SingletonOnModuleCase::Bar.should.included_called?
   end
 end
diff --git a/spec/ruby/core/module/instance_method_spec.rb b/spec/ruby/core/module/instance_method_spec.rb
index b4d6a0d8c8..8615e352f6 100644
--- a/spec/ruby/core/module/instance_method_spec.rb
+++ b/spec/ruby/core/module/instance_method_spec.rb
@@ -9,7 +9,7 @@ describe "Module#instance_method" do
   end
 
   it "is a public method" do
-    Module.should have_public_instance_method(:instance_method, false)
+    Module.public_instance_methods(false).should.include?(:instance_method)
   end
 
   it "requires an argument" do
@@ -17,26 +17,26 @@ describe "Module#instance_method" do
   end
 
   it "returns an UnboundMethod corresponding to the given name" do
-    @parent_um.should be_kind_of(UnboundMethod)
+    @parent_um.should.is_a?(UnboundMethod)
     @parent_um.bind(ModuleSpecs::InstanceMeth.new).call.should == :foo
   end
 
   it "returns an UnboundMethod corresponding to the given name from a superclass" do
-    @child_um.should be_kind_of(UnboundMethod)
+    @child_um.should.is_a?(UnboundMethod)
     @child_um.bind(ModuleSpecs::InstanceMethChild.new).call.should == :foo
   end
 
   it "returns an UnboundMethod corresponding to the given name from an included Module" do
-    @mod_um.should be_kind_of(UnboundMethod)
+    @mod_um.should.is_a?(UnboundMethod)
     @mod_um.bind(ModuleSpecs::InstanceMethChild.new).call.should == :bar
   end
 
   it "returns an UnboundMethod when given a protected method name" do
-    ModuleSpecs::Basic.instance_method(:protected_module).should be_an_instance_of(UnboundMethod)
+    ModuleSpecs::Basic.instance_method(:protected_module).should.instance_of?(UnboundMethod)
   end
 
   it "returns an UnboundMethod when given a private method name" do
-    ModuleSpecs::Basic.instance_method(:private_module).should be_an_instance_of(UnboundMethod)
+    ModuleSpecs::Basic.instance_method(:private_module).should.instance_of?(UnboundMethod)
   end
 
   it "gives UnboundMethod method name, Module defined in and Module extracted from" do
@@ -45,20 +45,41 @@ describe "Module#instance_method" do
     @parent_um.inspect.should =~ /\bModuleSpecs::InstanceMeth\b/
     @child_um.inspect.should =~ /\bfoo\b/
     @child_um.inspect.should =~ /\bModuleSpecs::InstanceMeth\b/
-    @child_um.inspect.should =~ /\bModuleSpecs::InstanceMethChild\b/
+
     @mod_um.inspect.should =~ /\bbar\b/
     @mod_um.inspect.should =~ /\bModuleSpecs::InstanceMethMod\b/
-    @mod_um.inspect.should =~ /\bModuleSpecs::InstanceMethChild\b/
   end
 
-  it "raises a TypeError if not passed a symbol" do
-    -> { Object.instance_method([]) }.should raise_error(TypeError)
-    -> { Object.instance_method(0)  }.should raise_error(TypeError)
+  it "raises a TypeError if the given name is not a String/Symbol" do
+    -> { Object.instance_method([]) }.should.raise(TypeError, /is not a symbol nor a string/)
+    -> { Object.instance_method(0) }.should.raise(TypeError, /is not a symbol nor a string/)
+    -> { Object.instance_method(nil) }.should.raise(TypeError, /is not a symbol nor a string/)
+    -> { Object.instance_method(mock('x')) }.should.raise(TypeError, /is not a symbol nor a string/)
+  end
+
+  it "accepts String name argument" do
+    method = ModuleSpecs::InstanceMeth.instance_method(:foo)
+    method.should.is_a?(UnboundMethod)
+  end
+
+  it "accepts Symbol name argument"  do
+    method = ModuleSpecs::InstanceMeth.instance_method("foo")
+    method.should.is_a?(UnboundMethod)
   end
 
-  it "raises a TypeError if the given name is not a string/symbol" do
-    -> { Object.instance_method(nil)       }.should raise_error(TypeError)
-    -> { Object.instance_method(mock('x')) }.should raise_error(TypeError)
+  it "converts non-String name by calling #to_str method" do
+    obj = Object.new
+    def obj.to_str() "foo" end
+
+    method = ModuleSpecs::InstanceMeth.instance_method(obj)
+    method.should.is_a?(UnboundMethod)
+  end
+
+  it "raises TypeError when passed non-String name and #to_str returns non-String value" do
+    obj = Object.new
+    def obj.to_str() [] end
+
+    -> { ModuleSpecs::InstanceMeth.instance_method(obj) }.should raise_consistent_error(TypeError, /can't convert Object into String/)
   end
 
   it "raises a NameError if the method has been undefined" do
@@ -68,11 +89,11 @@ describe "Module#instance_method" do
     um.should == @parent_um
     -> do
       child.instance_method(:foo)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the method does not exist" do
-    -> { Object.instance_method(:missing) }.should raise_error(NameError)
+    -> { Object.instance_method(:missing) }.should.raise(NameError)
   end
 
   it "sets the NameError#name attribute to the name of the missing method" do
diff --git a/spec/ruby/core/module/instance_methods_spec.rb b/spec/ruby/core/module/instance_methods_spec.rb
index d2d38cdda2..dbb6df8c34 100644
--- a/spec/ruby/core/module/instance_methods_spec.rb
+++ b/spec/ruby/core/module/instance_methods_spec.rb
@@ -4,21 +4,22 @@ require_relative 'fixtures/classes'
 describe "Module#instance_methods" do
   it "does not return methods undefined in a superclass" do
     methods = ModuleSpecs::Parent.instance_methods(false)
-    methods.should_not include(:undefed_method)
+    methods.should_not.include?(:undefed_method)
   end
 
   it "only includes module methods on an included module" do
     methods = ModuleSpecs::Basic.instance_methods(false)
-    methods.should include(:public_module)
+    methods.should.include?(:public_module)
     # Child is an including class
     methods = ModuleSpecs::Child.instance_methods(false)
-    methods.should include(:public_child)
-    methods.should_not include(:public_module)
+    methods.should.include?(:public_child)
+    methods.should_not.include?(:public_module)
   end
 
   it "does not return methods undefined in a subclass" do
     methods = ModuleSpecs::Grandchild.instance_methods
-    methods.should_not include(:parent_method, :another_parent_method)
+    methods.should_not.include?(:parent_method)
+    methods.should_not.include?(:another_parent_method)
   end
 
   it "does not return methods undefined in the current class" do
@@ -28,34 +29,35 @@ describe "Module#instance_methods" do
     end
     ModuleSpecs::Child.send(:undef_method, :undefed_child)
     methods = ModuleSpecs::Child.instance_methods
-    methods.should_not include(:undefed_method, :undefed_child)
+    methods.should_not.include?(:undefed_method)
+    methods.should_not.include?(:undefed_child)
   end
 
   it "does not return methods from an included module that are undefined in the class" do
-    ModuleSpecs::Grandchild.instance_methods.should_not include(:super_included_method)
+    ModuleSpecs::Grandchild.instance_methods.should_not.include?(:super_included_method)
   end
 
   it "returns the public and protected methods of self if include_super is false" do
     methods = ModuleSpecs::Parent.instance_methods(false)
-    methods.should include(:protected_parent, :public_parent)
+    methods.to_set.should >= Set[:protected_parent, :public_parent]
 
     methods = ModuleSpecs::Child.instance_methods(false)
-    methods.should include(:protected_child, :public_child)
+    methods.to_set.should >= Set[:protected_child, :public_child]
   end
 
   it "returns the public and protected methods of self and it's ancestors" do
     methods = ModuleSpecs::Basic.instance_methods
-    methods.should include(:protected_module, :public_module)
+    methods.to_set.should >= Set[:protected_module, :public_module]
 
     methods = ModuleSpecs::Super.instance_methods
-    methods.should include(:protected_module, :protected_super_module,
-                           :public_module, :public_super_module)
+    methods.to_set.should >= Set[:protected_module, :protected_super_module,
+                                 :public_module, :public_super_module]
   end
 
   it "makes a private Object instance method public in Kernel" do
     methods = Kernel.instance_methods
-    methods.should include(:module_specs_private_method_on_object_for_kernel_public)
+    methods.should.include?(:module_specs_private_method_on_object_for_kernel_public)
     methods = Object.instance_methods
-    methods.should_not include(:module_specs_private_method_on_object_for_kernel_public)
+    methods.should_not.include?(:module_specs_private_method_on_object_for_kernel_public)
   end
 end
diff --git a/spec/ruby/core/module/lt_spec.rb b/spec/ruby/core/module/lt_spec.rb
index d7771e07a8..8567a24993 100644
--- a/spec/ruby/core/module/lt_spec.rb
+++ b/spec/ruby/core/module/lt_spec.rb
@@ -10,10 +10,10 @@ describe "Module#<" do
   end
 
   it "returns false if self is a superclass of or included by the given module" do
-    (ModuleSpecs::Parent < ModuleSpecs::Child).should be_false
-    (ModuleSpecs::Basic < ModuleSpecs::Child).should be_false
-    (ModuleSpecs::Super < ModuleSpecs::Child).should be_false
-    (ModuleSpecs::Basic < ModuleSpecs::Super).should be_false
+    (ModuleSpecs::Parent < ModuleSpecs::Child).should == false
+    (ModuleSpecs::Basic < ModuleSpecs::Child).should == false
+    (ModuleSpecs::Super < ModuleSpecs::Child).should == false
+    (ModuleSpecs::Basic < ModuleSpecs::Super).should == false
   end
 
   it "returns false if self is the same as the given module" do
@@ -31,6 +31,6 @@ describe "Module#<" do
   end
 
   it "raises a TypeError if the argument is not a class/module" do
-    -> { ModuleSpecs::Parent < mock('x') }.should raise_error(TypeError)
+    -> { ModuleSpecs::Parent < mock('x') }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/lte_spec.rb b/spec/ruby/core/module/lte_spec.rb
index 7a0e8496b8..c6aab94e9f 100644
--- a/spec/ruby/core/module/lte_spec.rb
+++ b/spec/ruby/core/module/lte_spec.rb
@@ -28,6 +28,6 @@ describe "Module#<=" do
   end
 
   it "raises a TypeError if the argument is not a class/module" do
-    -> { ModuleSpecs::Parent <= mock('x') }.should raise_error(TypeError)
+    -> { ModuleSpecs::Parent <= mock('x') }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/module/method_added_spec.rb b/spec/ruby/core/module/method_added_spec.rb
index e1b1eda430..996a14eb86 100644
--- a/spec/ruby/core/module/method_added_spec.rb
+++ b/spec/ruby/core/module/method_added_spec.rb
@@ -2,8 +2,12 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Module#method_added" do
+  before :each do
+    ScratchPad.record []
+  end
+
   it "is a private instance method" do
-    Module.should have_private_instance_method(:method_added)
+    Module.private_instance_methods(false).should.include?(:method_added)
   end
 
   it "returns nil in the default implementation" do
@@ -13,8 +17,6 @@ describe "Module#method_added" do
   end
 
   it "is called when a new instance method is defined in self" do
-    ScratchPad.record []
-
     Module.new do
       def self.method_added(name)
         ScratchPad << name
@@ -32,8 +34,6 @@ describe "Module#method_added" do
 
   it "is not called when a singleton method is added" do
     # obj.singleton_method_added is called instead
-    ScratchPad.record []
-
     klass = Class.new
     def klass.method_added(name)
       ScratchPad << name
@@ -57,6 +57,90 @@ describe "Module#method_added" do
 
       undef_method :method_to_undef
     end
-    m.should_not have_method(:method_to_undef)
+    m.should_not.respond_to?(:method_to_undef)
+  end
+
+  it "is not called when a method changes visibility" do
+    Module.new do
+      def public_method
+      end
+
+      def private_method
+      end
+
+      def self.method_added(name)
+        ScratchPad << name
+      end
+
+      public :public_method
+      private :public_method
+
+      private :private_method
+      public :private_method
+    end
+
+    ScratchPad.recorded.should == []
+  end
+
+  it "is called when using #private in a subclass" do
+    parent = Class.new do
+      def foo
+      end
+    end
+
+    Class.new(parent) do
+      def self.method_added(name)
+        ScratchPad << name
+      end
+
+      # Create an instance as that might initialize some method lookup caches, which is interesting to test
+      self.new.foo
+
+      private :foo
+      public :foo
+    end
+
+    ScratchPad.recorded.should == [:foo]
+  end
+
+  it "is not called when a method is copied via module_function, rather #singleton_method_added is called" do
+    Module.new do
+      def mod_function
+      end
+
+      def self.method_added(name)
+        ScratchPad << [:method_added, name]
+      end
+
+      def self.singleton_method_added(name)
+        ScratchPad << [:singleton_method_added, name]
+      end
+
+      ScratchPad.record []
+
+      module_function :mod_function
+    end
+
+    ScratchPad.recorded.should == [[:singleton_method_added, :mod_function]]
+  end
+
+  it "is called with a precise caller location with the line of the 'def'" do
+    line = nil
+
+    Module.new do
+      def self.method_added(name)
+        location = caller_locations(1, 1)[0]
+        ScratchPad << location.lineno
+      end
+
+      line = __LINE__
+      def first
+      end
+
+      def second
+      end
+    end
+
+    ScratchPad.recorded.should == [line + 1, line + 4]
   end
 end
diff --git a/spec/ruby/core/module/method_defined_spec.rb b/spec/ruby/core/module/method_defined_spec.rb
index c2a8702d97..e6b4c7b817 100644
--- a/spec/ruby/core/module/method_defined_spec.rb
+++ b/spec/ruby/core/module/method_defined_spec.rb
@@ -27,17 +27,17 @@ describe "Module#method_defined?" do
   it "does not search Object or Kernel when called on a module" do
     m = Module.new
 
-    m.method_defined?(:module_specs_public_method_on_kernel).should be_false
+    m.method_defined?(:module_specs_public_method_on_kernel).should == false
   end
 
-  it "raises a TypeError when the given object is not a string/symbol/fixnum" do
+  it "raises a TypeError when the given object is not a string/symbol" do
     c = Class.new
     o = mock('123')
 
-    -> { c.method_defined?(o) }.should raise_error(TypeError)
+    -> { c.method_defined?(o) }.should.raise(TypeError)
 
     o.should_receive(:to_str).and_return(123)
-    -> { c.method_defined?(o) }.should raise_error(TypeError)
+    -> { c.method_defined?(o) }.should.raise(TypeError)
   end
 
   it "converts the given name to a string using to_str" do
@@ -47,54 +47,52 @@ describe "Module#method_defined?" do
     c.method_defined?(o).should == true
   end
 
-  ruby_version_is "2.6" do
-    # works as method_defined?(method_name)
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.method_defined?(:public_child, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_child, true).should == true
-        ModuleSpecs::Child.method_defined?(:accessor_method, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_child, true).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.method_defined?(:public_parent, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_parent, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_parent, true).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.method_defined?(:public_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_module, true).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.method_defined?(:public_super_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_super_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_super_module, true).should == false
-      end
+  # works as method_defined?(method_name)
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.method_defined?(:public_child, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_child, true).should == true
+      ModuleSpecs::Child.method_defined?(:accessor_method, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_child, true).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.method_defined?(:public_parent, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_parent, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_parent, true).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.method_defined?(:public_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_module, true).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.method_defined?(:public_super_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_super_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_super_module, true).should == false
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.method_defined?(:public_child, false).should == true
-        ModuleSpecs::Child.method_defined?(:protected_child, false).should == true
-        ModuleSpecs::Child.method_defined?(:accessor_method, false).should == true
-        ModuleSpecs::Child.method_defined?(:private_child, false).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.method_defined?(:public_child, false).should == true
+      ModuleSpecs::Child.method_defined?(:protected_child, false).should == true
+      ModuleSpecs::Child.method_defined?(:accessor_method, false).should == true
+      ModuleSpecs::Child.method_defined?(:private_child, false).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/method_removed_spec.rb b/spec/ruby/core/module/method_removed_spec.rb
index 9b39eb77a6..80e546406c 100644
--- a/spec/ruby/core/module/method_removed_spec.rb
+++ b/spec/ruby/core/module/method_removed_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#method_removed" do
   it "is a private instance method" do
-    Module.should have_private_instance_method(:method_removed)
+    Module.private_instance_methods(false).should.include?(:method_removed)
   end
 
   it "returns nil in the default implementation" do
diff --git a/spec/ruby/core/module/method_undefined_spec.rb b/spec/ruby/core/module/method_undefined_spec.rb
index a94388fe0a..596c5c50e2 100644
--- a/spec/ruby/core/module/method_undefined_spec.rb
+++ b/spec/ruby/core/module/method_undefined_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#method_undefined" do
   it "is a private instance method" do
-    Module.should have_private_instance_method(:method_undefined)
+    Module.private_instance_methods(false).should.include?(:method_undefined)
   end
 
   it "returns nil in the default implementation" do
diff --git a/spec/ruby/core/module/module_function_spec.rb b/spec/ruby/core/module/module_function_spec.rb
index 407237d48f..41bd152608 100644
--- a/spec/ruby/core/module/module_function_spec.rb
+++ b/spec/ruby/core/module/module_function_spec.rb
@@ -3,22 +3,22 @@ require_relative 'fixtures/classes'
 
 describe "Module#module_function" do
   it "is a private method" do
-    Module.should have_private_instance_method(:module_function)
+    Module.private_instance_methods(false).should.include?(:module_function)
   end
 
   describe "on Class" do
     it "is undefined" do
-      Class.should_not have_private_instance_method(:module_function, true)
+      Class.private_instance_methods(true).should_not.include?(:module_function)
     end
 
     it "raises a TypeError if calling after rebinded to Class" do
       -> {
         Module.instance_method(:module_function).bind(Class.new).call
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
 
       -> {
         Module.instance_method(:module_function).bind(Class.new).call :foo
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 end
@@ -38,14 +38,12 @@ describe "Module#module_function with specific method names" do
     m.respond_to?(:test3).should == false
   end
 
-  it "returns the current module" do
-    x = nil
-    m = Module.new do
-      def test()  end
-      x = module_function :test
+  it "returns argument or arguments if given" do
+    Module.new do
+      def foo; end
+      module_function(:foo).should.equal?(:foo)
+      module_function(:foo, :foo).should == [:foo, :foo]
     end
-
-    x.should == m
   end
 
   it "creates an independent copy of the method, not a redirect" do
@@ -85,9 +83,9 @@ describe "Module#module_function with specific method names" do
 
     (o = mock('x')).extend(m)
     o.respond_to?(:test).should == false
-    m.should have_private_instance_method(:test)
+    m.private_instance_methods(false).should.include?(:test)
     o.send(:test).should == "hello"
-    -> { o.test }.should raise_error(NoMethodError)
+    -> { o.test }.should.raise(NoMethodError)
   end
 
   it "makes the new Module methods public" do
@@ -116,17 +114,17 @@ describe "Module#module_function with specific method names" do
   it "raises a TypeError when the given names can't be converted to string using to_str" do
     o = mock('123')
 
-    -> { Module.new { module_function(o) } }.should raise_error(TypeError)
+    -> { Module.new { module_function(o) } }.should.raise(TypeError)
 
     o.should_receive(:to_str).and_return(123)
-    -> { Module.new { module_function(o) } }.should raise_error(TypeError)
+    -> { Module.new { module_function(o) } }.should.raise(TypeError)
   end
 
   it "can make accessible private methods" do # JRUBY-4214
     m = Module.new do
       module_function :require
     end
-    m.respond_to?(:require).should be_true
+    m.respond_to?(:require).should == true
   end
 
   it "creates Module methods that super up the singleton class of the module" do
@@ -146,38 +144,82 @@ describe "Module#module_function with specific method names" do
 
     m.foo.should == ["m", "super_m"]
   end
+
+  context "methods created with define_method" do
+    context "passed a block" do
+      it "creates duplicates of the given instance methods" do
+        m = Module.new do
+          define_method :test1 do; end
+          module_function :test1
+        end
+
+        m.respond_to?(:test1).should == true
+      end
+    end
+
+    context "passed a method" do
+      it "creates duplicates of the given instance methods" do
+        module_with_method = Module.new do
+          def test1; end
+        end
+
+        c = Class.new do
+          extend module_with_method
+        end
+
+        m = Module.new do
+          define_method :test2, c.method(:test1)
+          module_function :test2
+        end
+
+        m.respond_to?(:test2).should == true
+      end
+    end
+
+    context "passed an unbound method" do
+      it "creates duplicates of the given instance methods" do
+        module_with_method = Module.new do
+          def test1; end
+        end
+
+        m = Module.new do
+          define_method :test2, module_with_method.instance_method(:test1)
+          module_function :test2
+        end
+
+        m.respond_to?(:test2).should == true
+      end
+    end
+  end
 end
 
 describe "Module#module_function as a toggle (no arguments) in a Module body" do
   it "makes any subsequently defined methods module functions with the normal semantics" do
-    m = Module.new {
+    m = Module.new do
       module_function
       def test1() end
       def test2() end
-    }
+    end
 
     m.respond_to?(:test1).should == true
     m.respond_to?(:test2).should == true
   end
 
-  it "returns the current module" do
-    x = nil
-    m = Module.new {
-      x = module_function
-    }
-
-    x.should == m
+  it "returns nil" do
+    Module.new do
+      module_function.should.equal?(nil)
+    end
   end
 
   it "stops creating module functions if the body encounters another toggle " \
      "like public/protected/private without arguments" do
-    m = Module.new {
+    m = Module.new do
       module_function
       def test1() end
       def test2() end
       public
       def test3() end
-    }
+    end
 
     m.respond_to?(:test1).should == true
     m.respond_to?(:test2).should == true
@@ -186,14 +228,14 @@ describe "Module#module_function as a toggle (no arguments) in a Module body" do
 
   it "does not stop creating module functions if the body encounters " \
      "public/protected/private WITH arguments" do
-    m = Module.new {
+    m = Module.new do
       def foo() end
       module_function
       def test1() end
       def test2() end
       public :foo
       def test3() end
-    }
+    end
 
     m.respond_to?(:test1).should == true
     m.respond_to?(:test2).should == true
@@ -201,69 +243,116 @@ describe "Module#module_function as a toggle (no arguments) in a Module body" do
   end
 
   it "does not affect module_evaled method definitions also if outside the eval itself" do
-    m = Module.new {
+    m = Module.new do
       module_function
       module_eval { def test1() end }
       module_eval " def test2() end "
-    }
+    end
 
     m.respond_to?(:test1).should == false
     m.respond_to?(:test2).should == false
   end
 
   it "has no effect if inside a module_eval if the definitions are outside of it" do
-    m = Module.new {
+    m = Module.new do
       module_eval { module_function }
       def test1() end
       def test2() end
-    }
+    end
 
     m.respond_to?(:test1).should == false
     m.respond_to?(:test2).should == false
   end
 
   it "functions normally if both toggle and definitions inside a module_eval" do
-    m = Module.new {
-      module_eval {
+    m = Module.new do
+      module_eval do
         module_function
         def test1() end
         def test2() end
-      }
-    }
+      end
+    end
 
     m.respond_to?(:test1).should == true
     m.respond_to?(:test2).should == true
   end
 
-  it "affects evaled method definitions also even when outside the eval itself" do
-    m = Module.new {
+  it "affects eval'ed method definitions also even when outside the eval itself" do
+    m = Module.new do
       module_function
       eval "def test1() end"
-    }
+    end
 
     m.respond_to?(:test1).should == true
   end
 
   it "doesn't affect definitions when inside an eval even if the definitions are outside of it" do
-    m = Module.new {
+    m = Module.new do
       eval "module_function"
       def test1() end
-    }
+    end
 
     m.respond_to?(:test1).should == false
   end
 
   it "functions normally if both toggle and definitions inside a eval" do
-    m = Module.new {
+    m = Module.new do
       eval <<-CODE
         module_function
 
         def test1() end
         def test2() end
       CODE
-    }
+    end
 
     m.respond_to?(:test1).should == true
     m.respond_to?(:test2).should == true
   end
+
+  context "methods are defined with define_method" do
+    context "passed a block" do
+      it "makes any subsequently defined methods module functions with the normal semantics" do
+        m = Module.new do
+          module_function
+          define_method :test1 do; end
+        end
+
+        m.respond_to?(:test1).should == true
+      end
+    end
+
+    context "passed a method" do
+      it "makes any subsequently defined methods module functions with the normal semantics" do
+        module_with_method = Module.new do
+          def test1; end
+        end
+
+        c = Class.new do
+          extend module_with_method
+        end
+
+        m = Module.new do
+          module_function
+          define_method :test2, c.method(:test1)
+        end
+
+        m.respond_to?(:test2).should == true
+      end
+    end
+
+    context "passed an unbound method" do
+      it "makes any subsequently defined methods module functions with the normal semantics" do
+        module_with_method = Module.new do
+          def test1; end
+        end
+
+        m = Module.new do
+          module_function
+          define_method :test2, module_with_method.instance_method(:test1)
+        end
+
+        m.respond_to?(:test2).should == true
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/module/name_spec.rb b/spec/ruby/core/module/name_spec.rb
index 36a91f5be5..332c08d782 100644
--- a/spec/ruby/core/module/name_spec.rb
+++ b/spec/ruby/core/module/name_spec.rb
@@ -3,13 +3,13 @@ require_relative 'fixtures/module'
 
 describe "Module#name" do
   it "is nil for an anonymous module" do
-    Module.new.name.should be_nil
+    Module.new.name.should == nil
   end
 
-  it "is nil when assigned to a constant in an anonymous module" do
+  it "is not nil when assigned to a constant in an anonymous module" do
     m = Module.new
     m::N = Module.new
-    m::N.name.should be_nil
+    m::N.name.should.end_with? '::N'
   end
 
   it "is not nil for a nested module created with the module keyword" do
@@ -18,12 +18,33 @@ describe "Module#name" do
     m::N.name.should =~ /\A#<Module:0x[0-9a-f]+>::N\z/
   end
 
+  it "returns nil for a singleton class" do
+    Module.new.singleton_class.name.should == nil
+    String.singleton_class.name.should == nil
+    Object.new.singleton_class.name.should == nil
+  end
+
   it "changes when the module is reachable through a constant path" do
     m = Module.new
     module m::N; end
     m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
     ModuleSpecs::Anonymous::WasAnnon = m::N
     m::N.name.should == "ModuleSpecs::Anonymous::WasAnnon"
+  ensure
+    ModuleSpecs::Anonymous.send(:remove_const, :WasAnnon)
+  end
+
+  it "may be the repeated in different module objects" do
+    m = Module.new
+    n = Module.new
+
+    suppress_warning do
+      ModuleSpecs::Anonymous::SameName = m
+      ModuleSpecs::Anonymous::SameName = n
+    end
+
+    m.name.should == "ModuleSpecs::Anonymous::SameName"
+    n.name.should == "ModuleSpecs::Anonymous::SameName"
   end
 
   it "is set after it is removed from a constant" do
@@ -53,10 +74,20 @@ describe "Module#name" do
     ModuleSpecs::Anonymous.name.should == "ModuleSpecs::Anonymous"
   end
 
-  it "is set when assigning to a constant" do
+  it "is set when assigning to a constant (constant path matches outer module name)" do
     m = Module.new
     ModuleSpecs::Anonymous::A = m
     m.name.should == "ModuleSpecs::Anonymous::A"
+  ensure
+    ModuleSpecs::Anonymous.send(:remove_const, :A)
+  end
+
+  it "is set when assigning to a constant (constant path does not match outer module name)" do
+    m = Module.new
+    ModuleSpecs::Anonymous::SameChild::A = m
+    m.name.should == "ModuleSpecs::Anonymous::Child::A"
+  ensure
+    ModuleSpecs::Anonymous::SameChild.send(:remove_const, :A)
   end
 
   it "is not modified when assigning to a new constant after it has been accessed" do
@@ -65,6 +96,9 @@ describe "Module#name" do
     m.name.should == "ModuleSpecs::Anonymous::B"
     ModuleSpecs::Anonymous::C = m
     m.name.should == "ModuleSpecs::Anonymous::B"
+  ensure
+    ModuleSpecs::Anonymous.send(:remove_const, :B)
+    ModuleSpecs::Anonymous.send(:remove_const, :C)
   end
 
   it "is not modified when assigned to a different anonymous module" do
@@ -95,34 +129,77 @@ describe "Module#name" do
     ModuleSpecs::NameEncoding.new.name.encoding.should == Encoding::UTF_8
   end
 
-  it "is set when the anonymous outer module name is set" do
+  it "is set when the anonymous outer module name is set (module in one single constant)" do
     m = Module.new
     m::N = Module.new
     ModuleSpecs::Anonymous::E = m
     m::N.name.should == "ModuleSpecs::Anonymous::E::N"
+  ensure
+    ModuleSpecs::Anonymous.send(:remove_const, :E)
   end
 
-  ruby_version_is ""..."2.7" do
-    it "returns a mutable string" do
-      ModuleSpecs.name.frozen?.should be_false
-    end
+  # https://bugs.ruby-lang.org/issues/19681
+  it "is set when the anonymous outer module name is set (module in several constants)" do
+    m = Module.new
+    m::N = Module.new
+    m::O = m::N
+    ModuleSpecs::Anonymous::StoredInMultiplePlaces = m
+    valid_names = [
+      "ModuleSpecs::Anonymous::StoredInMultiplePlaces::N",
+      "ModuleSpecs::Anonymous::StoredInMultiplePlaces::O"
+    ]
+    valid_names.should.include?(m::N.name) # You get one of the two, but you don't know which one.
+  ensure
+    ModuleSpecs::Anonymous.send(:remove_const, :StoredInMultiplePlaces)
+  end
+
+  it "is set in #const_added callback when a module defined in the top-level scope" do
+    ruby_exe(<<~RUBY, args: "2>&1").chomp.should == "TEST1\nTEST2"
+      class Module
+        def const_added(name)
+          puts const_get(name).name
+        end
+      end
 
-    it "returns a mutable string that when mutated does not modify the original module name" do
-      ModuleSpecs.name << "foo"
+      # module with name
+      module TEST1
+      end
 
-      ModuleSpecs.name.should == "ModuleSpecs"
-    end
+      # anonymous module
+      TEST2 = Module.new
+    RUBY
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen String" do
-      ModuleSpecs.name.frozen?.should == true
-    end
+  it "is set in #const_added callback for a nested module when an outer module defined in the top-level scope" do
+    ScratchPad.record []
+
+    ModuleSpecs::NameSpecs::NamedModule = Module.new do
+      def self.const_added(name)
+        ScratchPad << const_get(name).name
+      end
+
+      module self::A
+        def self.const_added(name)
+          ScratchPad << const_get(name).name
+        end
 
-    it "always returns the same String for a given Module" do
-      s1 = ModuleSpecs.name
-      s2 = ModuleSpecs.name
-      s1.should equal(s2)
+        module self::B
+        end
+      end
     end
+
+    ScratchPad.recorded.should.one?(/#<Module.+>::A$/)
+    ScratchPad.recorded.should.one?(/#<Module.+>::A::B$/)
+    ModuleSpecs::NameSpecs.send :remove_const, :NamedModule
+  end
+
+  it "returns a frozen String" do
+    ModuleSpecs.name.should.frozen?
+  end
+
+  it "always returns the same String for a given Module" do
+    s1 = ModuleSpecs.name
+    s2 = ModuleSpecs.name
+    s1.should.equal?(s2)
   end
 end
diff --git a/spec/ruby/core/module/new_spec.rb b/spec/ruby/core/module/new_spec.rb
index da7f3b8720..ec7a0cfa77 100644
--- a/spec/ruby/core/module/new_spec.rb
+++ b/spec/ruby/core/module/new_spec.rb
@@ -6,6 +6,10 @@ describe "Module.new" do
     Module.new.is_a?(Module).should == true
   end
 
+  it "creates a module without a name" do
+    Module.new.name.should == nil
+  end
+
   it "creates a new Module and passes it to the provided block" do
     test_mod = nil
     m = Module.new do |mod|
diff --git a/spec/ruby/core/module/prepend_features_spec.rb b/spec/ruby/core/module/prepend_features_spec.rb
index b6fce9aba0..3a50f2c2a4 100644
--- a/spec/ruby/core/module/prepend_features_spec.rb
+++ b/spec/ruby/core/module/prepend_features_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#prepend_features" do
   it "is a private method" do
-    Module.should have_private_instance_method(:prepend_features, true)
+    Module.private_instance_methods(false).should.include?(:prepend_features)
   end
 
   it "gets called when self is included in another module/class" do
@@ -25,19 +25,7 @@ describe "Module#prepend_features" do
   it "raises an ArgumentError on a cyclic prepend" do
     -> {
       ModuleSpecs::CyclicPrepend.send(:prepend_features, ModuleSpecs::CyclicPrepend)
-    }.should raise_error(ArgumentError)
-  end
-
-  it "copies own tainted status to the given module" do
-    other = Module.new
-    Module.new.taint.send :prepend_features, other
-    other.tainted?.should be_true
-  end
-
-  it "copies own untrusted status to the given module" do
-    other = Module.new
-    Module.new.untrust.send :prepend_features, other
-    other.untrusted?.should be_true
+    }.should.raise(ArgumentError)
   end
 
   it "clears caches of the given module" do
@@ -64,13 +52,13 @@ describe "Module#prepend_features" do
 
   describe "on Class" do
     it "is undefined" do
-      Class.should_not have_private_instance_method(:prepend_features, true)
+      Class.private_instance_methods(true).should_not.include?(:prepend_features)
     end
 
     it "raises a TypeError if calling after rebinded to Class" do
       -> {
         Module.instance_method(:prepend_features).bind(Class.new).call Module.new
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/core/module/prepend_spec.rb b/spec/ruby/core/module/prepend_spec.rb
index e143f51673..f7887e6d6a 100644
--- a/spec/ruby/core/module/prepend_spec.rb
+++ b/spec/ruby/core/module/prepend_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#prepend" do
   it "is a public method" do
-    Module.should have_public_instance_method(:prepend, false)
+    Module.public_instance_methods(false).should.include?(:prepend)
   end
 
   it "does not affect the superclass" do
@@ -36,27 +36,450 @@ describe "Module#prepend" do
     ScratchPad.recorded.should == [ [ m3, c], [ m2, c ], [ m, c ] ]
   end
 
+  it "updates the method when a module is prepended" do
+    m_module = Module.new do
+      def foo
+        "m"
+      end
+    end
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+    a_class.class_eval do
+      prepend m_module
+    end
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when a prepended module is updated" do
+    m_module = Module.new
+    a_class = Class.new do
+      prepend m_module
+      def foo
+        'a'
+      end
+    end
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+    m_module.module_eval do
+      def foo
+        "m"
+      end
+    end
+    foo.call.should == 'm'
+  end
+
+  it "updates the optimized method when a prepended module is updated" do
+    out = ruby_exe(<<~RUBY)
+    module M; end
+    class Integer
+      prepend M
+    end
+    l = -> { 1 + 2 }
+    p l.call
+    M.module_eval do
+      def +(o)
+        $called = true
+        super(o)
+      end
+    end
+    p l.call
+    p $called
+    RUBY
+    out.should == "3\n3\ntrue\n"
+  end
+
+  it "updates the method when there is a base included method and the prepended module overrides it" do
+    base_module = Module.new do
+      def foo
+        'a'
+      end
+    end
+    a_class = Class.new do
+      include base_module
+    end
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+
+    m_module = Module.new do
+      def foo
+        "m"
+      end
+    end
+    a_class.prepend m_module
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when there is a base included method and the prepended module is later updated" do
+    base_module = Module.new do
+      def foo
+        'a'
+      end
+    end
+    a_class = Class.new do
+      include base_module
+    end
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+
+    m_module = Module.new
+    a_class.prepend m_module
+    foo.call.should == 'a'
+
+    m_module.module_eval do
+      def foo
+        "m"
+      end
+    end
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when a module prepended after a call is later updated" do
+    m_module = Module.new
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+
+    a_class.prepend m_module
+    foo.call.should == 'a'
+
+    m_module.module_eval do
+      def foo
+        "m"
+      end
+    end
+    foo.call.should == 'm'
+  end
+
+  it "updates the method when a module is prepended after another and the method is defined later on that module" do
+    m_module = Module.new do
+      def foo
+        'a'
+      end
+    end
+    a_class = Class.new
+    a_class.prepend m_module
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+
+    n_module = Module.new
+    a_class.prepend n_module
+    foo.call.should == 'a'
+
+    n_module.module_eval do
+      def foo
+        "n"
+      end
+    end
+    foo.call.should == 'n'
+  end
+
+  it "updates the method when a module is included in a prepended module and the method is defined later" do
+    a_class = Class.new
+    base_module = Module.new do
+      def foo
+        'a'
+      end
+    end
+    a_class.prepend base_module
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+
+    m_module = Module.new
+    n_module = Module.new
+    m_module.include n_module
+    a_class.prepend m_module
+
+    n_module.module_eval do
+      def foo
+        "n"
+      end
+    end
+    foo.call.should == 'n'
+  end
+
+  it "updates the method when a new module with an included module is prepended" do
+    a_class = Class.new do
+      def foo
+        'a'
+      end
+    end
+
+    n_module = Module.new do
+      def foo
+        'n'
+      end
+    end
+
+    m_module = Module.new  do
+      include n_module
+    end
+
+    a = a_class.new
+    foo = -> { a.foo }
+
+    foo.call.should == 'a'
+
+    a_class.class_eval do
+      prepend m_module
+    end
+
+    foo.call.should == 'n'
+  end
+
+  it "updates the constant when a module is prepended" do
+    module ModuleSpecs::ConstUpdatePrepended
+      module M
+        FOO = 'm'
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+      B.prepend M
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatePrepended)
+  end
+
+  it "updates the constant when a prepended module is updated" do
+    module ModuleSpecs::ConstPrependedUpdated
+      module M
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        prepend M
+        def self.foo
+          FOO
+        end
+      end
+      B.foo.should == 'a'
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstPrependedUpdated)
+  end
+
+  it "updates the constant when there is a base included constant and the prepended module overrides it" do
+    module ModuleSpecs::ConstIncludedPrependedOverride
+      module Base
+        FOO = 'a'
+      end
+      module A
+        include Base
+        def self.foo
+          FOO
+        end
+      end
+      A.foo.should == 'a'
+
+      module M
+        FOO = 'm'
+      end
+      A.prepend M
+      A.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstIncludedPrependedOverride)
+  end
+
+  it "updates the constant when there is a base included constant and the prepended module is later updated" do
+    module ModuleSpecs::ConstIncludedPrependedLaterUpdated
+      module Base
+        FOO = 'a'
+      end
+      module A
+        include Base
+        def self.foo
+          FOO
+        end
+      end
+      A.foo.should == 'a'
+
+      module M
+      end
+      A.prepend M
+      A.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      A.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstIncludedPrependedLaterUpdated)
+  end
+
+  it "updates the constant when a module prepended after a constant is later updated" do
+    module ModuleSpecs::ConstUpdatedPrependedAfterLaterUpdated
+      module M
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+      B.foo.should == 'a'
+
+      B.prepend M
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedPrependedAfterLaterUpdated)
+  end
+
+  it "updates the constant when a module is prepended after another and the constant is defined later on that module" do
+    module ModuleSpecs::ConstUpdatedPrependedAfterConstDefined
+      module M
+        FOO = 'm'
+      end
+      module A
+        prepend M
+        def self.foo
+          FOO
+        end
+      end
+
+      A.foo.should == 'm'
+
+      module N
+      end
+      A.prepend N
+      A.foo.should == 'm'
+
+      N.const_set(:FOO, 'n')
+      A.foo.should == 'n'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedPrependedAfterConstDefined)
+  end
+
+  it "updates the constant when a module is included in a prepended module and the constant is defined later" do
+    module ModuleSpecs::ConstUpdatedIncludedInPrependedConstDefinedLater
+      module A
+        def self.foo
+          FOO
+        end
+      end
+      module Base
+        FOO = 'a'
+      end
+
+      A.prepend Base
+      A.foo.should == 'a'
+
+      module N
+      end
+      module M
+        include N
+      end
+
+      A.prepend M
+
+      N.const_set(:FOO, 'n')
+      A.foo.should == 'n'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedIncludedInPrependedConstDefinedLater)
+  end
+
+  it "updates the constant when a new module with an included module is prepended" do
+    module ModuleSpecs::ConstUpdatedNewModuleIncludedPrepended
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+      module N
+        FOO = 'n'
+      end
+
+      module M
+        include N
+      end
+
+      B.foo.should == 'a'
+
+      B.prepend M
+      B.foo.should == 'n'
+    end
+  ensure
+    ModuleSpecs.send(:remove_const, :ConstUpdatedNewModuleIncludedPrepended)
+  end
+
   it "raises a TypeError when the argument is not a Module" do
-    -> { ModuleSpecs::Basic.prepend(Class.new) }.should raise_error(TypeError)
+    -> { ModuleSpecs::Basic.prepend(Class.new) }.should.raise(TypeError)
   end
 
   it "does not raise a TypeError when the argument is an instance of a subclass of Module" do
-    -> { ModuleSpecs::SubclassSpec.prepend(ModuleSpecs::Subclass.new) }.should_not raise_error(TypeError)
+    class ModuleSpecs::SubclassSpec::AClass
+    end
+    -> { ModuleSpecs::SubclassSpec::AClass.prepend(ModuleSpecs::Subclass.new) }.should_not.raise(TypeError)
+  ensure
+    ModuleSpecs::SubclassSpec.send(:remove_const, :AClass)
+  end
+
+  it "raises a TypeError when the argument is a refinement" do
+    refinement = nil
+
+    Module.new do
+      refine String do
+        refinement = self
+      end
+    end
+
+    -> { ModuleSpecs::Basic.prepend(refinement) }.should.raise(TypeError, "Cannot prepend refinement")
   end
 
   it "imports constants" do
     m1 = Module.new
     m1::MY_CONSTANT = 1
     m2 = Module.new { prepend(m1) }
-    m2.constants.should include(:MY_CONSTANT)
+    m2.constants.should.include?(:MY_CONSTANT)
   end
 
   it "imports instance methods" do
-    Module.new { prepend ModuleSpecs::A }.instance_methods.should include(:ma)
+    Module.new { prepend ModuleSpecs::A }.instance_methods.should.include?(:ma)
   end
 
   it "does not import methods to modules and classes" do
-    Module.new { prepend ModuleSpecs::A }.methods.should_not include(:ma)
+    Module.new { prepend ModuleSpecs::A }.methods.should_not.include?(:ma)
   end
 
   it "allows wrapping methods" do
@@ -82,7 +505,7 @@ describe "Module#prepend" do
 
   it "includes prepended modules in ancestors" do
     m = Module.new
-    Class.new { prepend(m) }.ancestors.should include(m)
+    Class.new { prepend(m) }.ancestors.should.include?(m)
   end
 
   it "reports the prepended module as the method owner" do
@@ -119,31 +542,31 @@ describe "Module#prepend" do
   it "sees an instance of a prepended class as kind of the prepended module" do
     m = Module.new
     c = Class.new { prepend(m) }
-    c.new.should be_kind_of(m)
+    c.new.should.is_a?(m)
   end
 
   it "keeps the module in the chain when dupping the class" do
     m = Module.new
     c = Class.new { prepend(m) }
-    c.dup.new.should be_kind_of(m)
+    c.dup.new.should.is_a?(m)
   end
 
-  it "keeps the module in the chain when dupping an intermediate module" do
+  it "uses only new module when dupping the module" do
     m1 = Module.new { def calc(x) x end }
     m2 = Module.new { prepend(m1) }
     c1 = Class.new { prepend(m2) }
     m2dup = m2.dup
-    m2dup.ancestors.should == [m2dup,m1,m2]
+    m2dup.ancestors.should == [m1,m2dup]
     c2 = Class.new { prepend(m2dup) }
     c1.ancestors[0,3].should == [m1,m2,c1]
-    c1.new.should be_kind_of(m1)
-    c2.ancestors[0,4].should == [m2dup,m1,m2,c2]
-    c2.new.should be_kind_of(m1)
+    c1.new.should.is_a?(m1)
+    c2.ancestors[0,3].should == [m1,m2dup,c2]
+    c2.new.should.is_a?(m1)
   end
 
   it "depends on prepend_features to add the module" do
     m = Module.new { def self.prepend_features(mod) end }
-    Class.new { prepend(m) }.ancestors.should_not include(m)
+    Class.new { prepend(m) }.ancestors.should_not.include?(m)
   end
 
   it "adds the module in the subclass chains" do
@@ -204,7 +627,7 @@ describe "Module#prepend" do
         super << :class
       end
     end
-    -> { c.new.chain }.should raise_error(NoMethodError)
+    -> { c.new.chain }.should.raise(NoMethodError)
   end
 
   it "calls prepended after prepend_features" do
@@ -223,12 +646,24 @@ describe "Module#prepend" do
     ScratchPad.recorded.should == [[:prepend_features, c], [:prepended, c]]
   end
 
+  it "prepends a module if it is included in a super class" do
+    module ModuleSpecs::M3
+      module M; end
+      class A; include M; end
+      class B < A; prepend M; end
+
+      all = [A, B, M]
+
+      (B.ancestors.filter { |a| all.include?(a) }).should == [M, B, A, M]
+    end
+  end
+
   it "detects cyclic prepends" do
     -> {
       module ModuleSpecs::P
         prepend ModuleSpecs::P
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "doesn't accept no-arguments" do
@@ -236,7 +671,7 @@ describe "Module#prepend" do
       Module.new do
         prepend
       end
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "returns the class it's included into" do
@@ -343,6 +778,33 @@ describe "Module#prepend" do
     ary.should == [3, 2, 1]
   end
 
+  it "does not prepend a second copy if the module already indirectly exists in the hierarchy" do
+    mod = Module.new do; end
+    submod = Module.new do; end
+    klass = Class.new do; end
+    klass.include(mod)
+    mod.prepend(submod)
+    klass.include(mod)
+
+    klass.ancestors.take(4).should == [klass, submod, mod, Object]
+  end
+
+  # https://bugs.ruby-lang.org/issues/17423
+  describe "when module already exists in ancestor chain" do
+    it "modifies the ancestor chain" do
+      m = Module.new do; end
+      a = Module.new do; end
+      b = Class.new do; end
+
+      b.include(a)
+      a.prepend(m)
+      b.ancestors.take(4).should == [b, m, a, Object]
+
+      b.prepend(m)
+      b.ancestors.take(5).should == [m, b, m, a, Object]
+    end
+  end
+
   describe "called on a module" do
     describe "included into a class"
     it "does not obscure the module's methods from reflective access" do
@@ -355,7 +817,7 @@ describe "Module#prepend" do
       pre = Module.new
       mod.prepend pre
 
-      cls.instance_methods.should include(:foo)
+      cls.instance_methods.should.include?(:foo)
     end
   end
 end
diff --git a/spec/ruby/core/module/prepended_spec.rb b/spec/ruby/core/module/prepended_spec.rb
index bd95d8fd05..ccd450d668 100644
--- a/spec/ruby/core/module/prepended_spec.rb
+++ b/spec/ruby/core/module/prepended_spec.rb
@@ -8,7 +8,7 @@ describe "Module#prepended" do
   end
 
   it "is a private method" do
-    Module.should have_private_instance_method(:prepended, true)
+    Module.private_instance_methods(false).should.include?(:prepended)
   end
 
   it "is invoked when self is prepended to another module or class" do
diff --git a/spec/ruby/core/module/private_class_method_spec.rb b/spec/ruby/core/module/private_class_method_spec.rb
index e35b50d986..7ce07f1600 100644
--- a/spec/ruby/core/module/private_class_method_spec.rb
+++ b/spec/ruby/core/module/private_class_method_spec.rb
@@ -22,11 +22,11 @@ describe "Module#private_class_method" do
   it "makes an existing class method private" do
     ModuleSpecs::Parent.private_method_1.should == nil
     ModuleSpecs::Parent.private_class_method :private_method_1
-    -> { ModuleSpecs::Parent.private_method_1  }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Parent.private_method_1  }.should.raise(NoMethodError)
 
     # Technically above we're testing the Singleton classes, class method(right?).
     # Try a "real" class method set private.
-    -> { ModuleSpecs::Parent.private_method }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Parent.private_method }.should.raise(NoMethodError)
   end
 
   it "makes an existing class method private up the inheritance tree" do
@@ -34,8 +34,8 @@ describe "Module#private_class_method" do
     ModuleSpecs::Child.private_method_1.should == nil
     ModuleSpecs::Child.private_class_method :private_method_1
 
-    -> { ModuleSpecs::Child.private_method_1 }.should raise_error(NoMethodError)
-    -> { ModuleSpecs::Child.private_method   }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Child.private_method_1 }.should.raise(NoMethodError)
+    -> { ModuleSpecs::Child.private_method   }.should.raise(NoMethodError)
   end
 
   it "accepts more than one method at a time" do
@@ -44,14 +44,14 @@ describe "Module#private_class_method" do
 
     ModuleSpecs::Child.private_class_method :private_method_1, :private_method_2
 
-    -> { ModuleSpecs::Child.private_method_1 }.should raise_error(NoMethodError)
-    -> { ModuleSpecs::Child.private_method_2 }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Child.private_method_1 }.should.raise(NoMethodError)
+    -> { ModuleSpecs::Child.private_method_2 }.should.raise(NoMethodError)
   end
 
   it "raises a NameError if class method doesn't exist" do
     -> do
       ModuleSpecs.private_class_method :no_method_here
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "makes a class method private" do
@@ -59,7 +59,7 @@ describe "Module#private_class_method" do
       def self.foo() "foo" end
       private_class_method :foo
     end
-    -> { c.foo }.should raise_error(NoMethodError)
+    -> { c.foo }.should.raise(NoMethodError)
   end
 
   it "raises a NameError when the given name is not a method" do
@@ -67,7 +67,7 @@ describe "Module#private_class_method" do
       Class.new do
         private_class_method :foo
       end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError when the given name is an instance method" do
@@ -76,6 +76,16 @@ describe "Module#private_class_method" do
         def foo() "foo" end
         private_class_method :foo
       end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
+  end
+
+  context "when single argument is passed and is an array" do
+    it "sets the visibility of the given methods to private" do
+      c = Class.new do
+        def self.foo() "foo" end
+        private_class_method [:foo]
+      end
+      -> { c.foo }.should.raise(NoMethodError)
+    end
   end
 end
diff --git a/spec/ruby/core/module/private_constant_spec.rb b/spec/ruby/core/module/private_constant_spec.rb
index 3a91b3c3cd..ca0df48c0b 100644
--- a/spec/ruby/core/module/private_constant_spec.rb
+++ b/spec/ruby/core/module/private_constant_spec.rb
@@ -8,7 +8,7 @@ describe "Module#private_constant" do
 
     -> do
       cls2.send :private_constant, :Foo
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "accepts strings as constant names" do
@@ -16,7 +16,7 @@ describe "Module#private_constant" do
     cls.const_set :Foo, true
     cls.send :private_constant, "Foo"
 
-    -> { cls::Foo }.should raise_error(NameError)
+    -> { cls::Foo }.should.raise(NameError)
   end
 
   it "accepts multiple names" do
@@ -26,7 +26,7 @@ describe "Module#private_constant" do
 
     mod.send :private_constant, :Foo, :Bar
 
-    -> {mod::Foo}.should raise_error(NameError)
-    -> {mod::Bar}.should raise_error(NameError)
+    -> {mod::Foo}.should.raise(NameError)
+    -> {mod::Bar}.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/module/private_instance_methods_spec.rb b/spec/ruby/core/module/private_instance_methods_spec.rb
index cce0f001bf..ae0f21d1dd 100644
--- a/spec/ruby/core/module/private_instance_methods_spec.rb
+++ b/spec/ruby/core/module/private_instance_methods_spec.rb
@@ -5,20 +5,20 @@ require_relative '../../fixtures/reflection'
 # TODO: rewrite
 describe "Module#private_instance_methods" do
   it "returns a list of private methods in module and its ancestors" do
-    ModuleSpecs::CountsMixin.should have_private_instance_method(:private_3)
+    ModuleSpecs::CountsMixin.private_instance_methods(false).should.include?(:private_3)
 
-    ModuleSpecs::CountsParent.should have_private_instance_method(:private_2)
-    ModuleSpecs::CountsParent.should have_private_instance_method(:private_3)
+    ModuleSpecs::CountsParent.private_instance_methods(false).should.include?(:private_2)
+    ModuleSpecs::CountsParent.private_instance_methods(true).should.include?(:private_3)
 
-    ModuleSpecs::CountsChild.should have_private_instance_method(:private_1)
-    ModuleSpecs::CountsChild.should have_private_instance_method(:private_2)
-    ModuleSpecs::CountsChild.should have_private_instance_method(:private_3)
+    ModuleSpecs::CountsChild.private_instance_methods(false).should.include?(:private_1)
+    ModuleSpecs::CountsChild.private_instance_methods(true).should.include?(:private_2)
+    ModuleSpecs::CountsChild.private_instance_methods(true).should.include?(:private_3)
   end
 
   it "when passed false as a parameter, should return only methods defined in that module" do
-    ModuleSpecs::CountsMixin.should have_private_instance_method(:private_3, false)
-    ModuleSpecs::CountsParent.should have_private_instance_method(:private_2, false)
-    ModuleSpecs::CountsChild.should have_private_instance_method(:private_1, false)
+    ModuleSpecs::CountsMixin.private_instance_methods(false).should.include?(:private_3)
+    ModuleSpecs::CountsParent.private_instance_methods(false).should.include?(:private_2)
+    ModuleSpecs::CountsChild.private_instance_methods(false).should.include?(:private_1)
   end
 
   it "default list should be the same as passing true as an argument" do
diff --git a/spec/ruby/core/module/private_method_defined_spec.rb b/spec/ruby/core/module/private_method_defined_spec.rb
index 515542d9df..f730decc0a 100644
--- a/spec/ruby/core/module/private_method_defined_spec.rb
+++ b/spec/ruby/core/module/private_method_defined_spec.rb
@@ -31,28 +31,28 @@ describe "Module#private_method_defined?" do
     ModuleSpecs::CountsMixin.private_method_defined?(:private_3).should == true
   end
 
-  it "raises a TypeError if passed a Fixnum" do
+  it "raises a TypeError if passed an Integer" do
     -> do
       ModuleSpecs::CountsMixin.private_method_defined?(1)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
     -> do
       ModuleSpecs::CountsMixin.private_method_defined?(nil)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false" do
     -> do
       ModuleSpecs::CountsMixin.private_method_defined?(false)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that does not defined #to_str" do
     -> do
       ModuleSpecs::CountsMixin.private_method_defined?(mock('x'))
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that defines #to_sym" do
@@ -61,7 +61,7 @@ describe "Module#private_method_defined?" do
 
     -> do
       ModuleSpecs::CountsMixin.private_method_defined?(sym)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "calls #to_str to convert an Object" do
@@ -70,53 +70,51 @@ describe "Module#private_method_defined?" do
     ModuleSpecs::CountsMixin.private_method_defined?(str).should == true
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.private_method_defined?(:public_child, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_child, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:accessor_method, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_child, true).should == true
-
-        # Defined in Parent
-        ModuleSpecs::Child.private_method_defined?(:public_parent, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_parent, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_parent, true).should == true
-
-        # Defined in Module
-        ModuleSpecs::Child.private_method_defined?(:public_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_module, true).should == true
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.private_method_defined?(:public_super_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_super_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_super_module, true).should == true
-      end
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.private_method_defined?(:public_child, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_child, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:accessor_method, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_child, true).should == true
+
+      # Defined in Parent
+      ModuleSpecs::Child.private_method_defined?(:public_parent, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_parent, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_parent, true).should == true
+
+      # Defined in Module
+      ModuleSpecs::Child.private_method_defined?(:public_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_module, true).should == true
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.private_method_defined?(:public_super_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_super_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_super_module, true).should == true
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.private_method_defined?(:public_child, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_child, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:accessor_method, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_child, false).should == true
-
-        # Defined in Parent
-        ModuleSpecs::Child.private_method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.private_method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.private_method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.private_method_defined?(:public_child, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_child, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:accessor_method, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_child, false).should == true
+
+      # Defined in Parent
+      ModuleSpecs::Child.private_method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.private_method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.private_method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/private_spec.rb b/spec/ruby/core/module/private_spec.rb
index e893c24f38..e60fdb24cc 100644
--- a/spec/ruby/core/module/private_spec.rb
+++ b/spec/ruby/core/module/private_spec.rb
@@ -17,7 +17,7 @@ describe "Module#private" do
       private :foo
     end
 
-    -> { obj.foo }.should raise_error(NoMethodError)
+    -> { obj.foo }.should.raise(NoMethodError)
   end
 
   it "makes a public Object instance method private in a new module" do
@@ -25,31 +25,33 @@ describe "Module#private" do
       private :module_specs_public_method_on_object
     end
 
-    m.should have_private_instance_method(:module_specs_public_method_on_object)
+    m.private_instance_methods(false).should.include?(:module_specs_public_method_on_object)
 
     # Ensure we did not change Object's method
-    Object.should_not have_private_instance_method(:module_specs_public_method_on_object)
+    Object.private_instance_methods(true).should_not.include?(:module_specs_public_method_on_object)
   end
 
   it "makes a public Object instance method private in Kernel" do
-    Kernel.should have_private_instance_method(
+    Kernel.private_instance_methods(false).should.include?(
                   :module_specs_public_method_on_object_for_kernel_private)
-    Object.should_not have_private_instance_method(
+    Object.private_instance_methods(true).should_not.include?(
                   :module_specs_public_method_on_object_for_kernel_private)
   end
 
-  it "returns self" do
+  it "returns argument or arguments if given" do
     (class << Object.new; self; end).class_eval do
       def foo; end
-      private(:foo).should equal(self)
-      private.should equal(self)
+      private(:foo).should.equal?(:foo)
+      private([:foo, :foo]).should == [:foo, :foo]
+      private(:foo, :foo).should == [:foo, :foo]
+      private.should.equal?(nil)
     end
   end
 
   it "raises a NameError when given an undefined name" do
     -> do
       Module.new.send(:private, :undefined)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "only makes the method private in the class it is called on" do
@@ -69,7 +71,7 @@ describe "Module#private" do
     base.new.wrapped.should == 1
     -> do
       klass.new.wrapped
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "continues to allow a prepended module method to call super" do
diff --git a/spec/ruby/core/module/protected_instance_methods_spec.rb b/spec/ruby/core/module/protected_instance_methods_spec.rb
index 78ce7e788f..ea7ded030e 100644
--- a/spec/ruby/core/module/protected_instance_methods_spec.rb
+++ b/spec/ruby/core/module/protected_instance_methods_spec.rb
@@ -6,16 +6,16 @@ require_relative '../../fixtures/reflection'
 describe "Module#protected_instance_methods" do
   it "returns a list of protected methods in module and its ancestors" do
     methods = ModuleSpecs::CountsMixin.protected_instance_methods
-    methods.should include(:protected_3)
+    methods.should.include?(:protected_3)
 
     methods = ModuleSpecs::CountsParent.protected_instance_methods
-    methods.should include(:protected_3)
-    methods.should include(:protected_2)
+    methods.should.include?(:protected_3)
+    methods.should.include?(:protected_2)
 
     methods = ModuleSpecs::CountsChild.protected_instance_methods
-    methods.should include(:protected_3)
-    methods.should include(:protected_2)
-    methods.should include(:protected_1)
+    methods.should.include?(:protected_3)
+    methods.should.include?(:protected_2)
+    methods.should.include?(:protected_1)
   end
 
   it "when passed false as a parameter, should return only methods defined in that module" do
diff --git a/spec/ruby/core/module/protected_method_defined_spec.rb b/spec/ruby/core/module/protected_method_defined_spec.rb
index 7be7bdd3c9..78ba120c2f 100644
--- a/spec/ruby/core/module/protected_method_defined_spec.rb
+++ b/spec/ruby/core/module/protected_method_defined_spec.rb
@@ -31,28 +31,28 @@ describe "Module#protected_method_defined?" do
     ModuleSpecs::CountsMixin.protected_method_defined?(:protected_3).should == true
   end
 
-  it "raises a TypeError if passed a Fixnum" do
+  it "raises a TypeError if passed an Integer" do
     -> do
       ModuleSpecs::CountsMixin.protected_method_defined?(1)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
     -> do
       ModuleSpecs::CountsMixin.protected_method_defined?(nil)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false" do
     -> do
       ModuleSpecs::CountsMixin.protected_method_defined?(false)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that does not defined #to_str" do
     -> do
       ModuleSpecs::CountsMixin.protected_method_defined?(mock('x'))
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that defines #to_sym" do
@@ -61,7 +61,7 @@ describe "Module#protected_method_defined?" do
 
     -> do
       ModuleSpecs::CountsMixin.protected_method_defined?(sym)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "calls #to_str to convert an Object" do
@@ -70,53 +70,51 @@ describe "Module#protected_method_defined?" do
     ModuleSpecs::CountsMixin.protected_method_defined?(str).should == true
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.protected_method_defined?(:public_child, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_child, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:accessor_method, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_child, true).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.protected_method_defined?(:public_parent, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_parent, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_parent, true).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.protected_method_defined?(:public_module, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_module, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_module, true).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.protected_method_defined?(:public_super_module, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_super_module, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_super_module, true).should == false
-      end
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.protected_method_defined?(:public_child, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_child, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:accessor_method, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_child, true).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.protected_method_defined?(:public_parent, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_parent, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_parent, true).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.protected_method_defined?(:public_module, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_module, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_module, true).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.protected_method_defined?(:public_super_module, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_super_module, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_super_module, true).should == false
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.protected_method_defined?(:public_child, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_child, false).should == true
-        ModuleSpecs::Child.protected_method_defined?(:accessor_method, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_child, false).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.protected_method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.protected_method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.protected_method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.protected_method_defined?(:public_child, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_child, false).should == true
+      ModuleSpecs::Child.protected_method_defined?(:accessor_method, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_child, false).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.protected_method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.protected_method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.protected_method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/protected_spec.rb b/spec/ruby/core/module/protected_spec.rb
index aa04a42fb8..3ef6c76fae 100644
--- a/spec/ruby/core/module/protected_spec.rb
+++ b/spec/ruby/core/module/protected_spec.rb
@@ -18,7 +18,7 @@ describe "Module#protected" do
       protected :protected_method_1
     end
 
-    -> { ModuleSpecs::Parent.protected_method_1 }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Parent.protected_method_1 }.should.raise(NoMethodError)
   end
 
   it "makes a public Object instance method protected in a new module" do
@@ -26,30 +26,32 @@ describe "Module#protected" do
       protected :module_specs_public_method_on_object
     end
 
-    m.should have_protected_instance_method(:module_specs_public_method_on_object)
+    m.protected_instance_methods(false).should.include?(:module_specs_public_method_on_object)
 
     # Ensure we did not change Object's method
-    Object.should_not have_protected_instance_method(:module_specs_public_method_on_object)
+    Object.protected_instance_methods(true).should_not.include?(:module_specs_public_method_on_object)
   end
 
   it "makes a public Object instance method protected in Kernel" do
-    Kernel.should have_protected_instance_method(
+    Kernel.protected_instance_methods(false).should.include?(
                   :module_specs_public_method_on_object_for_kernel_protected)
-    Object.should_not have_protected_instance_method(
+    Object.protected_instance_methods(true).should_not.include?(
                   :module_specs_public_method_on_object_for_kernel_protected)
   end
 
-  it "returns self" do
+  it "returns argument or arguments if given" do
     (class << Object.new; self; end).class_eval do
       def foo; end
-      protected(:foo).should equal(self)
-      protected.should equal(self)
+      protected(:foo).should.equal?(:foo)
+      protected([:foo, :foo]).should == [:foo, :foo]
+      protected(:foo, :foo).should == [:foo, :foo]
+      protected.should.equal?(nil)
     end
   end
 
   it "raises a NameError when given an undefined name" do
     -> do
       Module.new.send(:protected, :undefined)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/module/public_class_method_spec.rb b/spec/ruby/core/module/public_class_method_spec.rb
index c09cc64863..4aca4d4311 100644
--- a/spec/ruby/core/module/public_class_method_spec.rb
+++ b/spec/ruby/core/module/public_class_method_spec.rb
@@ -18,7 +18,7 @@ describe "Module#public_class_method" do
   end
 
   it "makes an existing class method public" do
-    -> { ModuleSpecs::Parent.public_method_1 }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Parent.public_method_1 }.should.raise(NoMethodError)
     ModuleSpecs::Parent.public_class_method :public_method_1
     ModuleSpecs::Parent.public_method_1.should == nil
 
@@ -29,7 +29,7 @@ describe "Module#public_class_method" do
 
   it "makes an existing class method public up the inheritance tree" do
     ModuleSpecs::Child.private_class_method :public_method_1
-    -> { ModuleSpecs::Child.public_method_1 }.should raise_error(NoMethodError)
+    -> { ModuleSpecs::Child.public_method_1 }.should.raise(NoMethodError)
     ModuleSpecs::Child.public_class_method :public_method_1
 
     ModuleSpecs::Child.public_method_1.should == nil
@@ -37,8 +37,8 @@ describe "Module#public_class_method" do
   end
 
   it "accepts more than one method at a time" do
-    -> { ModuleSpecs::Parent.public_method_1 }.should raise_error(NameError)
-    -> { ModuleSpecs::Parent.public_method_2 }.should raise_error(NameError)
+    -> { ModuleSpecs::Parent.public_method_1 }.should.raise(NameError)
+    -> { ModuleSpecs::Parent.public_method_2 }.should.raise(NameError)
 
     ModuleSpecs::Child.public_class_method :public_method_1, :public_method_2
 
@@ -49,7 +49,7 @@ describe "Module#public_class_method" do
   it "raises a NameError if class method doesn't exist" do
     -> do
       ModuleSpecs.public_class_method :no_method_here
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "makes a class method public" do
@@ -66,7 +66,7 @@ describe "Module#public_class_method" do
       Class.new do
         public_class_method :foo
       end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError when the given name is an instance method" do
@@ -75,6 +75,20 @@ describe "Module#public_class_method" do
         def foo() "foo" end
         public_class_method :foo
       end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
+  end
+
+  context "when single argument is passed and is an array" do
+    it "makes a class method public" do
+      c = Class.new do
+        class << self
+          private
+          def foo() "foo" end
+        end
+        public_class_method [:foo]
+      end
+
+      c.foo.should == "foo"
+    end
   end
 end
diff --git a/spec/ruby/core/module/public_constant_spec.rb b/spec/ruby/core/module/public_constant_spec.rb
index e624d45fd2..87a051f125 100644
--- a/spec/ruby/core/module/public_constant_spec.rb
+++ b/spec/ruby/core/module/public_constant_spec.rb
@@ -8,7 +8,7 @@ describe "Module#public_constant" do
 
     -> do
       cls2.send :public_constant, :Foo
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "accepts strings as constant names" do
diff --git a/spec/ruby/core/module/public_instance_method_spec.rb b/spec/ruby/core/module/public_instance_method_spec.rb
index ba19ad0404..87c1bae599 100644
--- a/spec/ruby/core/module/public_instance_method_spec.rb
+++ b/spec/ruby/core/module/public_instance_method_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Module#public_instance_method" do
   it "is a public method" do
-    Module.should have_public_instance_method(:public_instance_method, false)
+    Module.public_instance_methods(false).should.include?(:public_instance_method)
   end
 
   it "requires an argument" do
@@ -13,12 +13,12 @@ describe "Module#public_instance_method" do
   describe "when given a public method name" do
     it "returns an UnboundMethod corresponding to the defined Module" do
       ret = ModuleSpecs::Super.public_instance_method(:public_module)
-      ret.should be_an_instance_of(UnboundMethod)
-      ret.owner.should equal(ModuleSpecs::Basic)
+      ret.should.instance_of?(UnboundMethod)
+      ret.owner.should.equal?(ModuleSpecs::Basic)
 
       ret = ModuleSpecs::Super.public_instance_method(:public_super_module)
-      ret.should be_an_instance_of(UnboundMethod)
-      ret.owner.should equal(ModuleSpecs::Super)
+      ret.should.instance_of?(UnboundMethod)
+      ret.owner.should.equal?(ModuleSpecs::Super)
     end
 
     it "accepts if the name is a Symbol or String" do
@@ -28,31 +28,31 @@ describe "Module#public_instance_method" do
   end
 
   it "raises a TypeError when given a name is not Symbol or String" do
-    -> { Module.new.public_instance_method(nil) }.should raise_error(TypeError)
+    -> { Module.new.public_instance_method(nil) }.should.raise(TypeError)
   end
 
   it "raises a NameError when given a protected method name" do
     -> do
       ModuleSpecs::Basic.public_instance_method(:protected_module)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the method is private" do
     -> do
       ModuleSpecs::Basic.public_instance_method(:private_module)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the method has been undefined" do
     -> do
       ModuleSpecs::Parent.public_instance_method(:undefed_method)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "raises a NameError if the method does not exist" do
     -> do
       Module.new.public_instance_method(:missing)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "sets the NameError#name attribute to the name of the missing method" do
diff --git a/spec/ruby/core/module/public_instance_methods_spec.rb b/spec/ruby/core/module/public_instance_methods_spec.rb
index ae7d9b5ffb..edea00d927 100644
--- a/spec/ruby/core/module/public_instance_methods_spec.rb
+++ b/spec/ruby/core/module/public_instance_methods_spec.rb
@@ -7,19 +7,19 @@ require_relative '../../fixtures/reflection'
 describe "Module#public_instance_methods" do
   it "returns a list of public methods in module and its ancestors" do
     methods = ModuleSpecs::CountsMixin.public_instance_methods
-    methods.should include(:public_3)
+    methods.should.include?(:public_3)
 
     methods = ModuleSpecs::CountsParent.public_instance_methods
-    methods.should include(:public_3)
-    methods.should include(:public_2)
+    methods.should.include?(:public_3)
+    methods.should.include?(:public_2)
 
     methods = ModuleSpecs::CountsChild.public_instance_methods
-    methods.should include(:public_3)
-    methods.should include(:public_2)
-    methods.should include(:public_1)
+    methods.should.include?(:public_3)
+    methods.should.include?(:public_2)
+    methods.should.include?(:public_1)
 
     methods = ModuleSpecs::Child2.public_instance_methods
-    methods.should include(:foo)
+    methods.should.include?(:foo)
   end
 
   it "when passed false as a parameter, should return only methods defined in that module" do
diff --git a/spec/ruby/core/module/public_method_defined_spec.rb b/spec/ruby/core/module/public_method_defined_spec.rb
index d2fcfd1e72..70cd992358 100644
--- a/spec/ruby/core/module/public_method_defined_spec.rb
+++ b/spec/ruby/core/module/public_method_defined_spec.rb
@@ -31,28 +31,28 @@ describe "Module#public_method_defined?" do
     ModuleSpecs::CountsMixin.public_method_defined?(:public_3).should == true
   end
 
-  it "raises a TypeError if passed a Fixnum" do
+  it "raises a TypeError if passed an Integer" do
     -> do
       ModuleSpecs::CountsMixin.public_method_defined?(1)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
     -> do
       ModuleSpecs::CountsMixin.public_method_defined?(nil)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed false" do
     -> do
       ModuleSpecs::CountsMixin.public_method_defined?(false)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that does not defined #to_str" do
     -> do
       ModuleSpecs::CountsMixin.public_method_defined?(mock('x'))
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed an object that defines #to_sym" do
@@ -61,7 +61,7 @@ describe "Module#public_method_defined?" do
 
     -> do
       ModuleSpecs::CountsMixin.public_method_defined?(sym)
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "calls #to_str to convert an Object" do
diff --git a/spec/ruby/core/module/public_spec.rb b/spec/ruby/core/module/public_spec.rb
index e7059f6aa6..f35c64143b 100644
--- a/spec/ruby/core/module/public_spec.rb
+++ b/spec/ruby/core/module/public_spec.rb
@@ -14,31 +14,32 @@ describe "Module#public" do
       public :module_specs_private_method_on_object
     end
 
-    m.should have_public_instance_method(:module_specs_private_method_on_object)
+    m.public_instance_methods(false).should.include?(:module_specs_private_method_on_object)
 
     # Ensure we did not change Object's method
-    Object.should_not have_public_instance_method(:module_specs_private_method_on_object)
+    Object.public_instance_methods(true).should_not.include?(:module_specs_private_method_on_object)
   end
 
   it "makes a private Object instance method public in Kernel" do
-    Kernel.should have_public_instance_method(
+    Kernel.public_instance_methods(false).should.include?(
                   :module_specs_private_method_on_object_for_kernel_public)
-    Object.should_not have_public_instance_method(
+    Object.public_instance_methods(true).should_not.include?(
                   :module_specs_private_method_on_object_for_kernel_public)
   end
 
-  it "returns self" do
+  it "returns argument or arguments if given" do
     (class << Object.new; self; end).class_eval do
       def foo; end
-      private :foo
-      public(:foo).should equal(self)
-      public.should equal(self)
+      public(:foo).should.equal?(:foo)
+      public([:foo, :foo]).should == [:foo, :foo]
+      public(:foo, :foo).should == [:foo, :foo]
+      public.should.equal?(nil)
     end
   end
 
   it "raises a NameError when given an undefined name" do
     -> do
       Module.new.send(:public, :undefined)
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/module/refine_spec.rb b/spec/ruby/core/module/refine_spec.rb
index 66c19ddb66..d0fc7015f8 100644
--- a/spec/ruby/core/module/refine_spec.rb
+++ b/spec/ruby/core/module/refine_spec.rb
@@ -11,7 +11,7 @@ describe "Module#refine" do
     end
 
     mod.should_not == inner_self
-    inner_self.should be_kind_of(Module)
+    inner_self.should.is_a?(Module)
     inner_self.name.should == nil
   end
 
@@ -43,7 +43,7 @@ describe "Module#refine" do
       end
     end
 
-    inner_self.public_instance_methods.should include(:blah)
+    inner_self.public_instance_methods.should.include?(:blah)
   end
 
   it "returns created anonymous module" do
@@ -63,7 +63,7 @@ describe "Module#refine" do
       Module.new do
         refine {}
       end
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "raises TypeError if not passed a class" do
@@ -71,7 +71,7 @@ describe "Module#refine" do
       Module.new do
         refine("foo") {}
       end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError, "wrong argument type String (expected Class or Module)")
   end
 
   it "accepts a module as argument" do
@@ -84,7 +84,32 @@ describe "Module#refine" do
       end
     end
 
-    inner_self.public_instance_methods.should include(:blah)
+    inner_self.public_instance_methods.should.include?(:blah)
+  end
+
+  it "applies refinements to the module" do
+    refinement = Module.new do
+      refine(Enumerable) do
+        def foo?
+          self.any? ? "yes" : "no"
+        end
+      end
+    end
+
+    foo = Class.new do
+      using refinement
+
+      def initialize(items)
+        @items = items
+      end
+
+      def result
+        @items.foo?
+      end
+    end
+
+    foo.new([]).result.should == "no"
+    foo.new([1]).result.should == "yes"
   end
 
   it "raises ArgumentError if not given a block" do
@@ -92,7 +117,7 @@ describe "Module#refine" do
       Module.new do
         refine String
       end
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "applies refinements to calls in the refine block" do
@@ -111,7 +136,7 @@ describe "Module#refine" do
       refine(String) {def foo; "foo"; end}
       -> {
         "hello".foo
-      }.should raise_error(NoMethodError)
+      }.should.raise(NoMethodError)
     end
   end
 
@@ -120,7 +145,7 @@ describe "Module#refine" do
       refine(String) {def foo; 'foo'; end}
     end
 
-    -> {"hello".foo}.should raise_error(NoMethodError)
+    -> {"hello".foo}.should.raise(NoMethodError)
   end
 
   # When defining multiple refinements in the same module,
@@ -184,7 +209,7 @@ describe "Module#refine" do
 
         [1, 2].to_json_format
       end
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   # method lookup:
@@ -196,8 +221,10 @@ describe "Module#refine" do
   #   * The included modules of C
   describe "method lookup" do
     it "looks in the object singleton class first" do
+      refined_class = ModuleSpecs.build_refined_class
+
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
+        refine refined_class do
           def foo; "foo from refinement"; end
         end
       end
@@ -206,7 +233,7 @@ describe "Module#refine" do
       Module.new do
         using refinement
 
-        obj = ModuleSpecs::ClassWithFoo.new
+        obj = refined_class.new
         class << obj
           def foo; "foo from singleton class"; end
         end
@@ -216,68 +243,48 @@ describe "Module#refine" do
       result.should == "foo from singleton class"
     end
 
-    it "looks in prepended modules from the refinement first" do
-      refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
-          include ModuleSpecs::IncludedModule
-          prepend ModuleSpecs::PrependedModule
-
-          def foo; "foo from refinement"; end
+    it "looks in later included modules of the refined module first" do
+      a = Module.new do
+        def foo
+          "foo from A"
         end
       end
 
-      result = nil
-      Module.new do
-        using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
-      end
-
-      result.should == "foo from prepended module"
-    end
-
-    it "looks in refinement then" do
-      refinement = Module.new do
-        refine(ModuleSpecs::ClassWithFoo) do
-          include ModuleSpecs::IncludedModule
-
-          def foo; "foo from refinement"; end
+      include_me_later = Module.new do
+        def foo
+          "foo from IncludeMeLater"
         end
       end
 
-      result = nil
-      Module.new do
-        using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
+      c = Class.new do
+        include a
       end
 
-      result.should == "foo from refinement"
-    end
-
-    it "looks in included modules from the refinement then" do
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
-          include ModuleSpecs::IncludedModule
-        end
-      end
+         refine c do; end
+       end
 
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
+        c.include include_me_later
+        result = c.new.foo
       end
 
-      result.should == "foo from included module"
+      result.should == "foo from IncludeMeLater"
     end
 
     it "looks in the class then" do
+      refined_class = ModuleSpecs.build_refined_class
+
       refinement = Module.new do
-        refine(ModuleSpecs::ClassWithFoo) { }
+        refine(refined_class) { }
       end
 
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
+        result = refined_class.new.foo
       end
 
       result.should == "foo"
@@ -287,12 +294,14 @@ describe "Module#refine" do
 
   # methods in a subclass have priority over refinements in a superclass
   it "does not override methods in subclasses" do
-    subclass = Class.new(ModuleSpecs::ClassWithFoo) do
+    refined_class = ModuleSpecs.build_refined_class
+
+    subclass = Class.new(refined_class) do
       def foo; "foo from subclass"; end
     end
 
     refinement = Module.new do
-      refine ModuleSpecs::ClassWithFoo do
+      refine refined_class do
         def foo; "foo from refinement"; end
       end
     end
@@ -308,8 +317,10 @@ describe "Module#refine" do
 
   context "for methods accessed indirectly" do
     it "is honored by Kernel#send" do
+      refined_class = ModuleSpecs.build_refined_class
+
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo do
+        refine refined_class do
           def foo; "foo from refinement"; end
         end
       end
@@ -317,15 +328,17 @@ describe "Module#refine" do
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.send :foo
+        result = refined_class.new.send :foo
       end
 
       result.should == "foo from refinement"
     end
 
     it "is honored by BasicObject#__send__" do
+      refined_class = ModuleSpecs.build_refined_class
+
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo do
+        refine refined_class do
           def foo; "foo from refinement"; end
         end
       end
@@ -333,7 +346,7 @@ describe "Module#refine" do
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.__send__ :foo
+        result = refined_class.new.__send__ :foo
       end
 
       result.should == "foo from refinement"
@@ -357,80 +370,40 @@ describe "Module#refine" do
       result.should == ["(1)", "(2)", "(3)"]
     end
 
-    ruby_version_is "" ... "2.6" do
-      it "is not honored by Kernel#public_send" do
-        refinement = Module.new do
-          refine ModuleSpecs::ClassWithFoo do
-            def foo; "foo from refinement"; end
-          end
-        end
+    it "is honored by Kernel#public_send" do
+      refined_class = ModuleSpecs.build_refined_class
 
-        result = nil
-        Module.new do
-          using refinement
-          result = ModuleSpecs::ClassWithFoo.new.public_send :foo
+      refinement = Module.new do
+        refine refined_class do
+          def foo; "foo from refinement"; end
         end
-
-        result.should == "foo"
       end
-    end
 
-    ruby_version_is "2.6" do
-      it "is honored by Kernel#public_send" do
-        refinement = Module.new do
-          refine ModuleSpecs::ClassWithFoo do
-            def foo; "foo from refinement"; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = ModuleSpecs::ClassWithFoo.new.public_send :foo
-        end
-
-        result.should == "foo from refinement"
+      result = nil
+      Module.new do
+        using refinement
+        result = refined_class.new.public_send :foo
       end
-    end
-
-    ruby_version_is "" ... "2.5" do
-      it "is not honored by string interpolation" do
-        refinement = Module.new do
-          refine Integer do
-            def to_s
-              "foo"
-            end
-          end
-        end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = "#{1}"
-        end
-
-        result.should == "1"
-      end
+      result.should == "foo from refinement"
     end
 
-    ruby_version_is "2.5" do
-      it "is honored by string interpolation" do
-        refinement = Module.new do
-          refine Integer do
-            def to_s
-              "foo"
-            end
+    it "is honored by string interpolation" do
+      refinement = Module.new do
+        refine Integer do
+          def to_s
+            "foo"
           end
         end
+      end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = "#{1}"
-        end
-
-        result.should == "foo"
+      result = nil
+      Module.new do
+        using refinement
+        result = "#{1}"
       end
+
+      result.should == "foo"
     end
 
     it "is honored by Kernel#binding" do
@@ -458,166 +431,79 @@ describe "Module#refine" do
       result.should == "hello from refinement"
     end
 
-    ruby_version_is "" ... "2.7" do
-      it "is not honored by Kernel#method" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
+    it "is honored by Kernel#method" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
         end
-
-        -> {
-          Module.new do
-            using refinement
-            klass.new.method(:foo)
-          end
-        }.should raise_error(NameError, /undefined method `foo'/)
       end
-    end
-
-    ruby_version_is "2.7" do
-      it "is honored by Kernel#method" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.new.method(:foo).class
-        end
 
-        result.should == Method
+      result = nil
+      Module.new do
+        using refinement
+        result = klass.new.method(:foo).class
       end
-    end
 
-    ruby_version_is "" ... "2.7" do
-      it "is not honored by Kernel#instance_method" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        -> {
-          Module.new do
-            using refinement
-            klass.instance_method(:foo)
-          end
-        }.should raise_error(NameError, /undefined method `foo'/)
-      end
+      result.should == Method
     end
 
-    ruby_version_is "2.7" do
-      it "is honored by Kernel#method" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.instance_method(:foo).class
+    it "is honored by Kernel#public_method" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
         end
-
-        result.should == UnboundMethod
       end
-    end
 
-    ruby_version_is "" ... "2.6" do
-      it "is not honored by Kernel#respond_to?" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.new.respond_to?(:foo)
-        end
-
-        result.should == false
+      result = nil
+      Module.new do
+        using refinement
+        result = klass.new.public_method(:foo).class
       end
-    end
-
-    ruby_version_is "2.6" do
-      it "is honored by Kernel#respond_to?" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.new.respond_to?(:foo)
-        end
-
-        result.should == true
-      end
+      result.should == Method
     end
 
-    ruby_version_is ""..."2.6" do
-      it "is not honored by &" do
-        refinement = Module.new do
-          refine String do
-            def to_proc(*args)
-              -> * { 'foo' }
-            end
-          end
+    it "is honored by Kernel#instance_method" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
         end
+      end
 
-        -> do
-          Module.new do
-            using refinement
-            ["hola"].map(&"upcase")
-          end
-        end.should raise_error(TypeError, /wrong argument type String \(expected Proc\)/)
+      result = nil
+      Module.new do
+        using refinement
+        result = klass.instance_method(:foo).class
       end
-    end
 
-    ruby_version_is "2.6" do
-      it "is honored by &" do
-        refinement = Module.new do
-          refine String do
-            def to_proc(*args)
-              -> * { 'foo' }
-            end
-          end
-        end
+      result.should == UnboundMethod
+    end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = ["hola"].map(&"upcase")
+    it "is honored by Kernel#respond_to?" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
         end
+      end
 
-        result.should == ['foo']
+      result = nil
+      Module.new do
+        using refinement
+        result = klass.new.respond_to?(:foo)
       end
+
+      result.should == true
     end
-  end
 
-  context "when super is called in a refinement" do
-    it "looks in the included to refinery module" do
+    it "is honored by &" do
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
-          include ModuleSpecs::IncludedModule
-
-          def foo
-            super
+        refine String do
+          def to_proc(*args)
+            -> * { 'foo' }
           end
         end
       end
@@ -625,15 +511,19 @@ describe "Module#refine" do
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
+        result = ["hola"].map(&"upcase")
       end
 
-      result.should == "foo from included module"
+      result.should == ['foo']
     end
+  end
 
+  context "when super is called in a refinement" do
     it "looks in the refined class" do
+      refined_class = ModuleSpecs.build_refined_class
+
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
+        refine refined_class do
           def foo
             super
           end
@@ -643,7 +533,7 @@ describe "Module#refine" do
       result = nil
       Module.new do
         using refinement
-        result = ModuleSpecs::ClassWithFoo.new.foo
+        result = refined_class.new.foo
       end
 
       result.should == "foo"
@@ -652,19 +542,21 @@ describe "Module#refine" do
     # super in a method of a refinement invokes the method in the refined
     # class even if there is another refinement which has been activated
     # in the same context.
-    it "looks in the refined class even if there is another active refinement" do
+    it "looks in the refined class first if called from refined method" do
+      refined_class = ModuleSpecs.build_refined_class(for_super: true)
+
       refinement = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
+        refine refined_class do
           def foo
-            "foo from refinement"
+            [:R1]
           end
         end
       end
 
       refinement_with_super = Module.new do
-        refine ModuleSpecs::ClassWithFoo  do
+        refine refined_class do
           def foo
-            super
+            [:R2] + super
           end
         end
       end
@@ -673,10 +565,39 @@ describe "Module#refine" do
       Module.new do
         using refinement
         using refinement_with_super
-        result = ModuleSpecs::ClassWithFoo.new.foo
+        result = refined_class.new.foo
       end
 
-      result.should == "foo"
+      result.should == [:R2, :C]
+    end
+
+    it "looks only in the refined class even if there is another active refinement" do
+      refined_class = ModuleSpecs.build_refined_class(for_super: true)
+
+      refinement = Module.new do
+        refine refined_class do
+          def bar
+            "you cannot see me from super because I belong to another active R"
+          end
+        end
+      end
+
+      refinement_with_super = Module.new do
+        refine refined_class do
+          def bar
+            super
+          end
+        end
+      end
+
+
+      Module.new do
+        using refinement
+        using refinement_with_super
+        -> {
+          refined_class.new.bar
+        }.should.raise(NoMethodError)
+      end
     end
   end
 
@@ -689,7 +610,7 @@ describe "Module#refine" do
       }
       [1,2].orig_count.should == 2
     end
-    -> { [1,2].orig_count }.should raise_error(NoMethodError)
+    -> { [1,2].orig_count }.should.raise(NoMethodError)
   end
 
   it 'and alias_method aliases a method within a refinement module, but not outside it' do
@@ -701,7 +622,18 @@ describe "Module#refine" do
       }
       [1,2].orig_count.should == 2
     end
-    -> { [1,2].orig_count }.should raise_error(NoMethodError)
+    -> { [1,2].orig_count }.should.raise(NoMethodError)
+  end
+
+  it "and instance_methods returns a list of methods including those of the refined module" do
+    methods = Array.instance_methods
+    methods_2 = []
+    Module.new do
+      refine Array do
+        methods_2 = instance_methods
+      end
+    end
+    methods.should == methods_2
   end
 
   # Refinements are inherited by module inclusion.
@@ -772,11 +704,10 @@ describe "Module#refine" do
         end
       end
     end
-    spec = self
-    klass = Class.new { instance_methods.should_not spec.send(:include, :refinement_only_method) }
+    klass = Class.new { instance_methods.should_not.include?(:refinement_only_method) }
     instance = klass.new
-    instance.methods.should_not include :refinement_only_method
+    instance.methods.should_not.include? :refinement_only_method
     instance.respond_to?(:refinement_only_method).should == false
-    -> { instance.method :refinement_only_method }.should raise_error(NameError)
+    -> { instance.method :refinement_only_method }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/core/module/refinements_spec.rb b/spec/ruby/core/module/refinements_spec.rb
new file mode 100644
index 0000000000..05658a8b0e
--- /dev/null
+++ b/spec/ruby/core/module/refinements_spec.rb
@@ -0,0 +1,43 @@
+require_relative '../../spec_helper'
+
+describe "Module#refinements" do
+  it "returns refinements defined in a module" do
+    ScratchPad.record []
+
+    m = Module.new do
+      refine String do
+        ScratchPad << self
+      end
+
+      refine Array do
+        ScratchPad << self
+      end
+    end
+
+    m.refinements.sort_by(&:object_id).should == ScratchPad.recorded.sort_by(&:object_id)
+  end
+
+  it "does not return refinements defined in the included module" do
+    ScratchPad.record []
+
+    m1 = Module.new do
+      refine Integer do
+        nil
+      end
+    end
+
+    m2 = Module.new do
+      include m1
+
+      refine String do
+        ScratchPad << self
+      end
+    end
+
+    m2.refinements.should == ScratchPad.recorded
+  end
+
+  it "returns an empty array if no refinements defined in a module" do
+    Module.new.refinements.should == []
+  end
+end
diff --git a/spec/ruby/core/module/remove_class_variable_spec.rb b/spec/ruby/core/module/remove_class_variable_spec.rb
index ab9514adf6..fccb29f52d 100644
--- a/spec/ruby/core/module/remove_class_variable_spec.rb
+++ b/spec/ruby/core/module/remove_class_variable_spec.rb
@@ -18,27 +18,27 @@ describe "Module#remove_class_variable" do
     meta = obj.singleton_class
     meta.send :class_variable_set, :@@var, 1
     meta.send(:remove_class_variable, :@@var).should == 1
-    meta.class_variable_defined?(:@@var).should be_false
+    meta.class_variable_defined?(:@@var).should == false
   end
 
   it "raises a NameError when removing class variable declared in included module" do
     c = ModuleSpecs::RemoveClassVariable.new { include ModuleSpecs::MVars.dup }
-    -> { c.send(:remove_class_variable, :@@mvar) }.should raise_error(NameError)
+    -> { c.send(:remove_class_variable, :@@mvar) }.should.raise(NameError)
   end
 
   it "raises a NameError when passed a symbol with one leading @" do
-    -> { ModuleSpecs::MVars.send(:remove_class_variable, :@mvar) }.should raise_error(NameError)
+    -> { ModuleSpecs::MVars.send(:remove_class_variable, :@mvar) }.should.raise(NameError)
   end
 
   it "raises a NameError when passed a symbol with no leading @" do
-    -> { ModuleSpecs::MVars.send(:remove_class_variable, :mvar)  }.should raise_error(NameError)
+    -> { ModuleSpecs::MVars.send(:remove_class_variable, :mvar)  }.should.raise(NameError)
   end
 
   it "raises a NameError when an uninitialized class variable is given" do
-    -> { ModuleSpecs::MVars.send(:remove_class_variable, :@@nonexisting_class_variable) }.should raise_error(NameError)
+    -> { ModuleSpecs::MVars.send(:remove_class_variable, :@@nonexisting_class_variable) }.should.raise(NameError)
   end
 
   it "is public" do
-    Module.should_not have_private_instance_method(:remove_class_variable)
+    Module.private_instance_methods(true).should_not.include?(:remove_class_variable)
   end
 end
diff --git a/spec/ruby/core/module/remove_const_spec.rb b/spec/ruby/core/module/remove_const_spec.rb
index 20eb2dc3ed..4e4b9fcb45 100644
--- a/spec/ruby/core/module/remove_const_spec.rb
+++ b/spec/ruby/core/module/remove_const_spec.rb
@@ -7,13 +7,13 @@ describe "Module#remove_const" do
     ConstantSpecs::ModuleM::CS_CONST252.should == :const252
 
     ConstantSpecs::ModuleM.send :remove_const, :CS_CONST252
-    -> { ConstantSpecs::ModuleM::CS_CONST252 }.should raise_error(NameError)
+    -> { ConstantSpecs::ModuleM::CS_CONST252 }.should.raise(NameError)
 
     ConstantSpecs::ModuleM::CS_CONST253 = :const253
     ConstantSpecs::ModuleM::CS_CONST253.should == :const253
 
     ConstantSpecs::ModuleM.send :remove_const, "CS_CONST253"
-    -> { ConstantSpecs::ModuleM::CS_CONST253 }.should raise_error(NameError)
+    -> { ConstantSpecs::ModuleM::CS_CONST253 }.should.raise(NameError)
   end
 
   it "returns the value of the removed constant" do
@@ -23,7 +23,7 @@ describe "Module#remove_const" do
 
   it "raises a NameError and does not call #const_missing if the constant is not defined" do
     ConstantSpecs.should_not_receive(:const_missing)
-    -> { ConstantSpecs.send(:remove_const, :Nonexistent) }.should raise_error(NameError)
+    -> { ConstantSpecs.send(:remove_const, :Nonexistent) }.should.raise(NameError)
   end
 
   it "raises a NameError and does not call #const_missing if the constant is not defined directly in the module" do
@@ -34,28 +34,28 @@ describe "Module#remove_const" do
 
       -> do
         ConstantSpecs::ContainerA.send :remove_const, :CS_CONST255
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     ensure
       ConstantSpecs::ModuleM.send :remove_const, "CS_CONST255"
     end
   end
 
   it "raises a NameError if the name does not start with a capital letter" do
-    -> { ConstantSpecs.send :remove_const, "name" }.should raise_error(NameError)
+    -> { ConstantSpecs.send :remove_const, "name" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name starts with a non-alphabetic character" do
-    -> { ConstantSpecs.send :remove_const, "__CONSTX__" }.should raise_error(NameError)
-    -> { ConstantSpecs.send :remove_const, "@Name" }.should raise_error(NameError)
-    -> { ConstantSpecs.send :remove_const, "!Name" }.should raise_error(NameError)
-    -> { ConstantSpecs.send :remove_const, "::Name" }.should raise_error(NameError)
+    -> { ConstantSpecs.send :remove_const, "__CONSTX__" }.should.raise(NameError)
+    -> { ConstantSpecs.send :remove_const, "@Name" }.should.raise(NameError)
+    -> { ConstantSpecs.send :remove_const, "!Name" }.should.raise(NameError)
+    -> { ConstantSpecs.send :remove_const, "::Name" }.should.raise(NameError)
   end
 
   it "raises a NameError if the name contains non-alphabetic characters except '_'" do
     ConstantSpecs::ModuleM::CS_CONST256 = :const256
     ConstantSpecs::ModuleM.send :remove_const, "CS_CONST256"
-    -> { ConstantSpecs.send :remove_const, "Name=" }.should raise_error(NameError)
-    -> { ConstantSpecs.send :remove_const, "Name?" }.should raise_error(NameError)
+    -> { ConstantSpecs.send :remove_const, "Name=" }.should.raise(NameError)
+    -> { ConstantSpecs.send :remove_const, "Name?" }.should.raise(NameError)
   end
 
   it "calls #to_str to convert the given name to a String" do
@@ -67,18 +67,41 @@ describe "Module#remove_const" do
 
   it "raises a TypeError if conversion to a String by calling #to_str fails" do
     name = mock('123')
-    -> { ConstantSpecs.send :remove_const, name }.should raise_error(TypeError)
+    -> { ConstantSpecs.send :remove_const, name }.should.raise(TypeError)
 
     name.should_receive(:to_str).and_return(123)
-    -> { ConstantSpecs.send :remove_const, name }.should raise_error(TypeError)
+    -> { ConstantSpecs.send :remove_const, name }.should.raise(TypeError)
   end
 
   it "is a private method" do
-    Module.private_methods.should include(:remove_const)
+    Module.private_methods.should.include?(:remove_const)
   end
 
   it "returns nil when removing autoloaded constant" do
     ConstantSpecs.autoload :AutoloadedConstant, 'a_file'
-    ConstantSpecs.send(:remove_const, :AutoloadedConstant).should be_nil
+    ConstantSpecs.send(:remove_const, :AutoloadedConstant).should == nil
+  end
+
+  it "updates the constant value" do
+    module ConstantSpecs::RemovedConstantUpdate
+      module M
+        FOO = 'm'
+      end
+
+      module A
+        include M
+        FOO = 'a'
+        def self.foo
+          FOO
+        end
+      end
+
+      A.foo.should == 'a'
+
+      A.send(:remove_const,:FOO)
+      A.foo.should == 'm'
+    end
+  ensure
+    ConstantSpecs.send(:remove_const, :RemovedConstantUpdate)
   end
 end
diff --git a/spec/ruby/core/module/remove_method_spec.rb b/spec/ruby/core/module/remove_method_spec.rb
index ba08cc9b44..39add01e36 100644
--- a/spec/ruby/core/module/remove_method_spec.rb
+++ b/spec/ruby/core/module/remove_method_spec.rb
@@ -20,15 +20,8 @@ describe "Module#remove_method" do
     @module = Module.new { def method_to_remove; end }
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:remove_method, false)
-    end
-  end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:remove_method, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:remove_method)
   end
 
   it "removes the method from a class" do
@@ -50,6 +43,28 @@ describe "Module#remove_method" do
     x.method_to_remove.should == 1
   end
 
+  it "updates the method implementation" do
+    m_module = Module.new do
+      def foo
+        'm'
+      end
+    end
+
+    a_class = Class.new do
+      include m_module
+
+      def foo
+        'a'
+      end
+    end
+
+    a = a_class.new
+    foo = -> { a.foo }
+    foo.call.should == 'a'
+    a_class.remove_method(:foo)
+    foo.call.should == 'm'
+  end
+
   it "removes multiple methods with 1 call" do
     klass = Class.new do
       def method_to_remove_1; 1; end
@@ -73,14 +88,14 @@ describe "Module#remove_method" do
   end
 
   it "returns self" do
-    @module.send(:remove_method, :method_to_remove).should equal(@module)
+    @module.send(:remove_method, :method_to_remove).should.equal?(@module)
   end
 
   it "raises a NameError when attempting to remove method further up the inheritance tree" do
     Class.new(ModuleSpecs::Second) do
       -> {
         remove_method :method_to_remove
-      }.should raise_error(NameError)
+      }.should.raise(NameError)
     end
   end
 
@@ -88,7 +103,7 @@ describe "Module#remove_method" do
     Class.new(ModuleSpecs::Second) do
       -> {
         remove_method :blah
-      }.should raise_error(NameError)
+      }.should.raise(NameError)
     end
   end
 
@@ -97,20 +112,20 @@ describe "Module#remove_method" do
       @frozen = @module.dup.freeze
     end
 
-    it "raises a #{frozen_error_class} when passed a name" do
-      -> { @frozen.send :remove_method, :method_to_remove }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed a name" do
+      -> { @frozen.send :remove_method, :method_to_remove }.should.raise(FrozenError)
     end
 
-    it "raises a #{frozen_error_class} when passed a missing name" do
-      -> { @frozen.send :remove_method, :not_exist }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed a missing name" do
+      -> { @frozen.send :remove_method, :not_exist }.should.raise(FrozenError)
     end
 
     it "raises a TypeError when passed a not name" do
-      -> { @frozen.send :remove_method, Object.new }.should raise_error(TypeError)
+      -> { @frozen.send :remove_method, Object.new }.should.raise(TypeError)
     end
 
     it "does not raise exceptions when no arguments given" do
-      @frozen.send(:remove_method).should equal(@frozen)
+      @frozen.send(:remove_method).should.equal?(@frozen)
     end
   end
 end
diff --git a/spec/ruby/core/module/ruby2_keywords_spec.rb b/spec/ruby/core/module/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..e392642978
--- /dev/null
+++ b/spec/ruby/core/module/ruby2_keywords_spec.rb
@@ -0,0 +1,248 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#ruby2_keywords" do
+  class << self
+    ruby2_keywords def mark(*args)
+      args
+    end
+  end
+
+  it "marks the final hash argument as keyword hash" do
+    last = mark(1, 2, a: "a").last
+    Hash.ruby2_keywords_hash?(last).should == true
+  end
+
+  it "makes a copy of the hash and only marks the copy as keyword hash" do
+    obj = Object.new
+    obj.singleton_class.class_exec do
+      def regular(*args)
+        args.last
+      end
+    end
+
+    h = {a: 1}
+
+    last = mark(**h).last
+    Hash.ruby2_keywords_hash?(last).should == true
+    Hash.ruby2_keywords_hash?(h).should == false
+
+    last2 = mark(**last).last # last is already marked
+    Hash.ruby2_keywords_hash?(last2).should == true
+    Hash.ruby2_keywords_hash?(last).should == true
+    last2.should_not.equal?(last)
+    Hash.ruby2_keywords_hash?(h).should == false
+  end
+
+  it "makes a copy and unmark the Hash when calling a method taking (arg)" do
+    obj = Object.new
+    obj.singleton_class.class_exec do
+      def single(arg)
+        arg
+      end
+    end
+
+    h = { a: 1 }
+    args = mark(**h)
+    marked = args.last
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    after_usage = obj.single(*args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+  end
+
+  it "makes a copy and unmark the Hash when calling a method taking (**kw)" do
+    obj = Object.new
+    obj.singleton_class.class_exec do
+      def kwargs(**kw)
+        kw
+      end
+    end
+
+    h = { a: 1 }
+    args = mark(**h)
+    marked = args.last
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    after_usage = obj.kwargs(*args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+  end
+
+  it "makes a copy and unmark the Hash when calling a method taking (*args)" do
+    obj = Object.new
+    obj.singleton_class.class_exec do
+      def splat(*args)
+        args.last
+      end
+
+      def splat1(arg, *args)
+        args.last
+      end
+
+      def proc_call(*args)
+        -> *a { a.last }.call(*args)
+      end
+    end
+
+    h = { a: 1 }
+    args = mark(**h)
+    marked = args.last
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    after_usage = obj.splat(*args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    args = mark(1, **h)
+    marked = args.last
+    after_usage = obj.splat1(*args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    args = mark(**h)
+    marked = args.last
+    after_usage = obj.proc_call(*args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+
+    args = mark(**h)
+    marked = args.last
+    after_usage = obj.send(:splat, *args)
+    after_usage.should == h
+    after_usage.should_not.equal?(h)
+    after_usage.should_not.equal?(marked)
+    Hash.ruby2_keywords_hash?(after_usage).should == false
+    Hash.ruby2_keywords_hash?(marked).should == true
+  end
+
+  it "applies to the underlying method and applies across aliasing" do
+    obj = Object.new
+
+    obj.singleton_class.class_exec do
+      def foo(*a) a.last end
+      alias_method :bar, :foo
+      ruby2_keywords :foo
+
+      def baz(*a) a.last end
+      ruby2_keywords :baz
+      alias_method :bob, :baz
+    end
+
+    last = obj.foo(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+
+    last = obj.bar(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+
+    last = obj.baz(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+
+    last = obj.bob(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+  end
+
+  it "returns nil" do
+    obj = Object.new
+
+    obj.singleton_class.class_exec do
+      def foo(*a) end
+
+      ruby2_keywords(:foo).should == nil
+    end
+  end
+
+  it "raises NameError when passed not existing method name" do
+    obj = Object.new
+
+    -> {
+      obj.singleton_class.class_exec do
+        ruby2_keywords :not_existing
+      end
+    }.should.raise(NameError, /undefined method [`']not_existing'/)
+  end
+
+  it "accepts String as well" do
+    obj = Object.new
+
+    obj.singleton_class.class_exec do
+      def foo(*a) a.last end
+      ruby2_keywords "foo"
+    end
+
+    last = obj.foo(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+  end
+
+  it "raises TypeError when passed not Symbol or String" do
+    obj = Object.new
+
+    -> {
+      obj.singleton_class.class_exec do
+        ruby2_keywords Object.new
+      end
+    }.should.raise(TypeError, /is not a symbol nor a string/)
+  end
+
+  it "prints warning when a method does not accept argument splat" do
+    obj = Object.new
+    def obj.foo(a, b, c) end
+
+    -> {
+      obj.singleton_class.class_exec do
+        ruby2_keywords :foo
+      end
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  it "prints warning when a method accepts keywords" do
+    obj = Object.new
+    def obj.foo(*a, b:) end
+
+    -> {
+      obj.singleton_class.class_exec do
+        ruby2_keywords :foo
+      end
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  it "prints warning when a method accepts keyword splat" do
+    obj = Object.new
+    def obj.foo(*a, **b) end
+
+    -> {
+      obj.singleton_class.class_exec do
+        ruby2_keywords :foo
+      end
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  ruby_version_is "4.0" do
+    it "prints warning when a method accepts post arguments" do
+      obj = Object.new
+      def obj.foo(*a, b) end
+
+      -> {
+        obj.singleton_class.class_exec do
+          ruby2_keywords :foo
+        end
+      }.should complain(/Skipping set of ruby2_keywords flag for/)
+    end
+  end
+end
diff --git a/spec/ruby/core/module/set_temporary_name_spec.rb b/spec/ruby/core/module/set_temporary_name_spec.rb
new file mode 100644
index 0000000000..7c159121fa
--- /dev/null
+++ b/spec/ruby/core/module/set_temporary_name_spec.rb
@@ -0,0 +1,145 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_temporary_name'
+
+describe "Module#set_temporary_name" do
+  it "can assign a temporary name" do
+    m = Module.new
+    m.name.should == nil
+
+    m.set_temporary_name("fake_name")
+    m.name.should == "fake_name"
+
+    m.set_temporary_name(nil)
+    m.name.should == nil
+  end
+
+  it "returns self" do
+    m = Module.new
+    m.set_temporary_name("fake_name").should.equal? m
+  end
+
+  it "can assign a temporary name which is not a valid constant path" do
+    m = Module.new
+
+    m.set_temporary_name("name")
+    m.name.should == "name"
+
+    m.set_temporary_name("Template['foo.rb']")
+    m.name.should == "Template['foo.rb']"
+
+    m.set_temporary_name("a::B")
+    m.name.should == "a::B"
+
+    m.set_temporary_name("A::b")
+    m.name.should == "A::b"
+
+    m.set_temporary_name("A::B::")
+    m.name.should == "A::B::"
+
+    m.set_temporary_name("A::::B")
+    m.name.should == "A::::B"
+
+    m.set_temporary_name("A=")
+    m.name.should == "A="
+  end
+
+  it "can't assign empty string as name" do
+    m = Module.new
+    -> { m.set_temporary_name("") }.should.raise(ArgumentError, "empty class/module name")
+  end
+
+  it "can't assign a constant name as a temporary name" do
+    m = Module.new
+    -> { m.set_temporary_name("Object") }.should.raise(ArgumentError, "the temporary name must not be a constant path to avoid confusion")
+  end
+
+  it "can't assign a constant path as a temporary name" do
+    m = Module.new
+    -> { m.set_temporary_name("A::B") }.should.raise(ArgumentError, "the temporary name must not be a constant path to avoid confusion")
+    -> { m.set_temporary_name("::A") }.should.raise(ArgumentError, "the temporary name must not be a constant path to avoid confusion")
+    -> { m.set_temporary_name("::A::B") }.should.raise(ArgumentError, "the temporary name must not be a constant path to avoid confusion")
+  end
+
+  it "can't assign name to permanent module" do
+    -> { Object.set_temporary_name("fake_name") }.should.raise(RuntimeError, "can't change permanent name")
+  end
+
+  it "can assign a temporary name to a module nested into an anonymous module" do
+    m = Module.new
+    module m::N; end
+    m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
+
+    m::N.set_temporary_name("fake_name")
+    m::N.name.should == "fake_name"
+
+    m::N.set_temporary_name(nil)
+    m::N.name.should == nil
+  end
+
+  it "discards a temporary name when an outer anonymous module gets a permanent name" do
+    m = Module.new
+    module m::N; end
+
+    m::N.set_temporary_name("fake_name")
+    m::N.name.should == "fake_name"
+
+    ModuleSpecs::SetTemporaryNameSpec::M = m
+    m::N.name.should == "ModuleSpecs::SetTemporaryNameSpec::M::N"
+    ModuleSpecs::SetTemporaryNameSpec.send :remove_const, :M
+  end
+
+  it "can update the name when assigned to a constant" do
+    m = Module.new
+    m::N = Module.new
+    m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
+    m::N.set_temporary_name(nil)
+
+    m::M = m::N
+    m::M.name.should =~ /\A#<Module:0x\h+>::M\z/m
+  end
+
+  it "can reassign a temporary name repeatedly" do
+    m = Module.new
+
+    m.set_temporary_name("fake_name")
+    m.name.should == "fake_name"
+
+    m.set_temporary_name("fake_name_2")
+    m.name.should == "fake_name_2"
+  end
+
+  ruby_bug "#21094", ""..."4.0" do
+    it "also updates a name of a nested module" do
+      m = Module.new
+      m::N = Module.new
+      m::N.name.should =~ /\A#<Module:0x\h+>::N\z/
+
+      m.set_temporary_name "m"
+      m::N.name.should == "m::N"
+
+      m.set_temporary_name nil
+      m::N.name.should == nil
+    end
+  end
+
+  it "keeps temporary name when assigned in an anonymous module" do
+    outer = Module.new
+    m = Module.new
+    m.set_temporary_name "m"
+    m.name.should == "m"
+    outer::M = m
+    m.name.should == "m"
+    m.inspect.should == "m"
+  end
+
+  it "keeps temporary name when assigned in an anonymous module and nested before" do
+    outer = Module.new
+    m = Module.new
+    outer::A = m
+    m.set_temporary_name "m"
+    m.name.should == "m"
+    outer::M = m
+    m.name.should == "m"
+    m.inspect.should == "m"
+  end
+end
diff --git a/spec/ruby/core/module/shared/attr_added.rb b/spec/ruby/core/module/shared/attr_added.rb
new file mode 100644
index 0000000000..ce832cdcff
--- /dev/null
+++ b/spec/ruby/core/module/shared/attr_added.rb
@@ -0,0 +1,34 @@
+describe :module_attr_added, shared: true do
+  it "calls method_added for normal classes" do
+    ScratchPad.record []
+
+    cls = Class.new do
+      class << self
+        def method_added(name)
+          ScratchPad.recorded << name
+        end
+      end
+    end
+
+    cls.send(@method, :foo)
+
+    ScratchPad.recorded.each {|name| name.to_s.should =~ /foo[=]?/}
+  end
+
+  it "calls singleton_method_added for singleton classes" do
+    ScratchPad.record []
+    cls = Class.new do
+      class << self
+        def singleton_method_added(name)
+          # called for this def so ignore it
+          return if name == :singleton_method_added
+          ScratchPad.recorded << name
+        end
+      end
+    end
+
+    cls.singleton_class.send(@method, :foo)
+
+    ScratchPad.recorded.each {|name| name.to_s.should =~ /foo[=]?/}
+  end
+end
diff --git a/spec/ruby/core/module/shared/class_eval.rb b/spec/ruby/core/module/shared/class_eval.rb
index 08f8ff7597..ee2860449a 100644
--- a/spec/ruby/core/module/shared/class_eval.rb
+++ b/spec/ruby/core/module/shared/class_eval.rb
@@ -14,7 +14,7 @@ describe :module_class_eval, shared: true do
         'foo'
       end
     end
-    -> {42.foo}.should raise_error(NoMethodError)
+    -> {42.foo}.should.raise(NoMethodError)
   end
 
   it "resolves constants in the caller scope" do
@@ -45,50 +45,63 @@ describe :module_class_eval, shared: true do
     ModuleSpecs.send(@method) do |block_parameter|
       given = block_parameter
     end
-    given.should equal ModuleSpecs
+    given.should.equal? ModuleSpecs
   end
 
   it "uses the optional filename and lineno parameters for error messages" do
     ModuleSpecs.send(@method, "[__FILE__, __LINE__]", "test", 102).should == ["test", 102]
   end
 
+  it "uses the caller location as default filename" do
+    ModuleSpecs.send(@method, "[__FILE__, __LINE__]").should == ["(eval at #{__FILE__}:#{__LINE__})", 1]
+  end
+
   it "converts a non-string filename to a string using to_str" do
     (file = mock(__FILE__)).should_receive(:to_str).and_return(__FILE__)
     ModuleSpecs.send(@method, "1+1", file)
+
+    (file = mock(__FILE__)).should_receive(:to_str).and_return(__FILE__)
+    ModuleSpecs.send(@method, "1+1", file, 15)
   end
 
   it "raises a TypeError when the given filename can't be converted to string using to_str" do
     (file = mock('123')).should_receive(:to_str).and_return(123)
-    -> { ModuleSpecs.send(@method, "1+1", file) }.should raise_error(TypeError)
+    -> { ModuleSpecs.send(@method, "1+1", file) }.should raise_consistent_error(TypeError, /can't convert MockObject into String/)
   end
 
   it "converts non string eval-string to string using to_str" do
     (o = mock('1 + 1')).should_receive(:to_str).and_return("1 + 1")
     ModuleSpecs.send(@method, o).should == 2
+
+    (o = mock('1 + 1')).should_receive(:to_str).and_return("1 + 1")
+    ModuleSpecs.send(@method, o, "file.rb").should == 2
+
+    (o = mock('1 + 1')).should_receive(:to_str).and_return("1 + 1")
+    ModuleSpecs.send(@method, o, "file.rb", 15).should == 2
   end
 
   it "raises a TypeError when the given eval-string can't be converted to string using to_str" do
     o = mock('x')
-    -> { ModuleSpecs.send(@method, o) }.should raise_error(TypeError)
+    -> { ModuleSpecs.send(@method, o) }.should.raise(TypeError, "no implicit conversion of MockObject into String")
 
     (o = mock('123')).should_receive(:to_str).and_return(123)
-    -> { ModuleSpecs.send(@method, o) }.should raise_error(TypeError)
+    -> { ModuleSpecs.send(@method, o) }.should raise_consistent_error(TypeError, /can't convert MockObject into String/)
   end
 
   it "raises an ArgumentError when no arguments and no block are given" do
-    -> { ModuleSpecs.send(@method) }.should raise_error(ArgumentError)
+    -> { ModuleSpecs.send(@method) }.should.raise(ArgumentError, "wrong number of arguments (given 0, expected 1..3)")
   end
 
   it "raises an ArgumentError when more than 3 arguments are given" do
     -> {
       ModuleSpecs.send(@method, "1 + 1", "some file", 0, "bogus")
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 1..3)")
   end
 
   it "raises an ArgumentError when a block and normal arguments are given" do
     -> {
       ModuleSpecs.send(@method, "1 + 1") { 1 + 1 }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, "wrong number of arguments (given 1, expected 0)")
   end
 
   # This case was found because Rubinius was caching the compiled
@@ -112,4 +125,48 @@ describe :module_class_eval, shared: true do
     a.attribute.should == "A"
     b.attribute.should == "B"
   end
+
+  it "activates refinements from the eval scope" do
+    refinery = Module.new do
+      refine ModuleSpecs::NamedClass do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    mid = @method
+    result = nil
+
+    Class.new do
+      using refinery
+
+      result = send(mid, "ModuleSpecs::NamedClass.new.foo")
+    end
+
+    result.should == "bar"
+  end
+
+  it "activates refinements from the eval scope with block" do
+    refinery = Module.new do
+      refine ModuleSpecs::NamedClass do
+        def foo
+          "bar"
+        end
+      end
+    end
+
+    mid = @method
+    result = nil
+
+    Class.new do
+      using refinery
+
+      result = send(mid) do
+        ModuleSpecs::NamedClass.new.foo
+      end
+    end
+
+    result.should == "bar"
+  end
 end
diff --git a/spec/ruby/core/module/shared/class_exec.rb b/spec/ruby/core/module/shared/class_exec.rb
index c7a9e5297f..e51af1966d 100644
--- a/spec/ruby/core/module/shared/class_exec.rb
+++ b/spec/ruby/core/module/shared/class_exec.rb
@@ -5,7 +5,7 @@ describe :module_class_exec, shared: true do
         'foo'
       end
     end
-    -> {42.foo}.should raise_error(NoMethodError)
+    -> {42.foo}.should.raise(NoMethodError)
   end
 
   it "defines method in the receiver's scope" do
@@ -19,11 +19,17 @@ describe :module_class_exec, shared: true do
   end
 
   it "raises a LocalJumpError when no block is given" do
-    -> { ModuleSpecs::Subclass.send(@method) }.should raise_error(LocalJumpError)
+    -> { ModuleSpecs::Subclass.send(@method) }.should.raise(LocalJumpError)
   end
 
   it "passes arguments to the block" do
     a = ModuleSpecs::Subclass
-    a.send(@method, 1) { |b| b }.should equal(1)
+    a.send(@method, 1) { |b| b }.should.equal?(1)
+  end
+
+  describe "with optional argument" do
+    it "does not destructure a single array argument" do
+      ModuleSpecs::Subclass.send(@method, [1, 2, 3]) { |a = 99| a }.should == [1, 2, 3]
+    end
   end
 end
diff --git a/spec/ruby/core/module/shared/set_visibility.rb b/spec/ruby/core/module/shared/set_visibility.rb
index c39d59e05d..38cc2ad260 100644
--- a/spec/ruby/core/module/shared/set_visibility.rb
+++ b/spec/ruby/core/module/shared/set_visibility.rb
@@ -2,7 +2,56 @@
 
 describe :set_visibility, shared: true do
   it "is a private method" do
-    Module.should have_private_instance_method(@method, false)
+    Module.private_instance_methods(false).should.include?(@method)
+  end
+
+  describe "with argument" do
+    describe "one or more arguments" do
+      it "sets visibility of given method names" do
+        visibility = @method
+        old_visibility = [:protected, :private].find {|vis| vis != visibility }
+
+        mod = Module.new {
+          send old_visibility
+          def test1() end
+          def test2() end
+          send visibility, :test1, :test2
+        }
+        mod.send(:"#{visibility}_instance_methods", false).should.include?(:test1)
+        mod.send(:"#{visibility}_instance_methods", false).should.include?(:test2)
+      end
+    end
+
+    describe "array as a single argument" do
+      it "sets visibility of given method names" do
+        visibility = @method
+        old_visibility = [:protected, :private].find {|vis| vis != visibility }
+
+        mod = Module.new {
+          send old_visibility
+          def test1() end
+          def test2() end
+          send visibility, [:test1, :test2]
+        }
+        mod.send(:"#{visibility}_instance_methods", false).should.include?(:test1)
+        mod.send(:"#{visibility}_instance_methods", false).should.include?(:test2)
+      end
+    end
+
+    it "does not clone method from the ancestor when setting to the same visibility in a child" do
+      visibility = @method
+      parent = Module.new {
+        def test_method; end
+        send(visibility, :test_method)
+      }
+
+      child = Module.new {
+        include parent
+        send(visibility, :test_method)
+      }
+
+      child.send(:"#{visibility}_instance_methods", false).should_not.include?(:test_method)
+    end
   end
 
   describe "without arguments" do
@@ -15,8 +64,8 @@ describe :set_visibility, shared: true do
         def test2() end
       }
 
-      mod.should send(:"have_#{@method}_instance_method", :test1, false)
-      mod.should send(:"have_#{@method}_instance_method", :test2, false)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test1)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test2)
     end
 
     it "stops setting visibility if the body encounters other visibility setters without arguments" do
@@ -29,7 +78,7 @@ describe :set_visibility, shared: true do
         def test1() end
       }
 
-      mod.should send(:"have_#{new_visibility}_instance_method", :test1, false)
+      mod.send(:"#{new_visibility}_instance_methods", false).should.include?(:test1)
     end
 
     it "continues setting visibility if the body encounters other visibility setters with arguments" do
@@ -41,7 +90,7 @@ describe :set_visibility, shared: true do
         def test2() end
       }
 
-      mod.should send(:"have_#{@method}_instance_method", :test2, false)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test2)
     end
 
     it "does not affect module_evaled method definitions when itself is outside the eval" do
@@ -53,8 +102,8 @@ describe :set_visibility, shared: true do
         module_eval " def test2() end "
       }
 
-      mod.should have_public_instance_method(:test1, false)
-      mod.should have_public_instance_method(:test2, false)
+      mod.public_instance_methods(false).should.include?(:test1)
+      mod.public_instance_methods(false).should.include?(:test2)
     end
 
     it "does not affect outside method definitions when itself is inside a module_eval" do
@@ -65,7 +114,7 @@ describe :set_visibility, shared: true do
         def test1() end
       }
 
-      mod.should have_public_instance_method(:test1, false)
+      mod.public_instance_methods(false).should.include?(:test1)
     end
 
     it "affects normally if itself and method definitions are inside a module_eval" do
@@ -78,7 +127,7 @@ describe :set_visibility, shared: true do
         }
       }
 
-      mod.should send(:"have_#{@method}_instance_method", :test1, false)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test1)
     end
 
     it "does not affect method definitions when itself is inside an eval and method definitions are outside" do
@@ -91,7 +140,7 @@ describe :set_visibility, shared: true do
         def test1() end
       }
 
-      mod.should send(:"have_#{initialized_visibility}_instance_method", :test1, false)
+      mod.send(:"#{initialized_visibility}_instance_methods", false).should.include?(:test1)
     end
 
     it "affects evaled method definitions when itself is outside the eval" do
@@ -102,7 +151,7 @@ describe :set_visibility, shared: true do
         eval "def test1() end"
       }
 
-      mod.should send(:"have_#{@method}_instance_method", :test1, false)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test1)
     end
 
     it "affects normally if itself and following method definitions are inside a eval" do
@@ -115,7 +164,7 @@ describe :set_visibility, shared: true do
         CODE
       }
 
-      mod.should send(:"have_#{@method}_instance_method", :test1, false)
+      mod.send(:"#{@method}_instance_methods", false).should.include?(:test1)
     end
 
     describe "within a closure" do
@@ -128,7 +177,7 @@ describe :set_visibility, shared: true do
           def test1() end
         }
 
-        mod.should send(:"have_#{@method}_instance_method", :test1, false)
+        mod.send(:"#{@method}_instance_methods", false).should.include?(:test1)
       end
     end
   end
diff --git a/spec/ruby/core/module/singleton_class_spec.rb b/spec/ruby/core/module/singleton_class_spec.rb
index b9f78eeb21..052755b73b 100644
--- a/spec/ruby/core/module/singleton_class_spec.rb
+++ b/spec/ruby/core/module/singleton_class_spec.rb
@@ -3,25 +3,25 @@ require_relative '../../spec_helper'
 describe "Module#singleton_class?" do
   it "returns true for singleton classes" do
     xs = self.singleton_class
-    xs.singleton_class?.should == true
+    xs.should.singleton_class?
   end
 
   it "returns false for other classes" do
     c = Class.new
-    c.singleton_class?.should == false
+    c.should_not.singleton_class?
   end
 
   describe "with singleton values" do
     it "returns false for nil's singleton class" do
-      NilClass.singleton_class?.should == false
+      NilClass.should_not.singleton_class?
     end
 
     it "returns false for true's singleton class" do
-      TrueClass.singleton_class?.should == false
+      TrueClass.should_not.singleton_class?
     end
 
     it "returns false for false's singleton class" do
-      FalseClass.singleton_class?.should == false
+      FalseClass.should_not.singleton_class?
     end
   end
 end
diff --git a/spec/ruby/core/module/to_s_spec.rb b/spec/ruby/core/module/to_s_spec.rb
index bebdcf6e1b..83c0ae0825 100644
--- a/spec/ruby/core/module/to_s_spec.rb
+++ b/spec/ruby/core/module/to_s_spec.rb
@@ -2,17 +2,69 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Module#to_s" do
+  it 'returns the name of the module if it has a name' do
+    Enumerable.to_s.should == 'Enumerable'
+    String.to_s.should == 'String'
+  end
+
   it "returns the full constant path leading to the module" do
     ModuleSpecs::LookupMod.to_s.should == "ModuleSpecs::LookupMod"
   end
 
   it "works with an anonymous module" do
     m = Module.new
-    m.to_s.should =~ /#<Module:0x[0-9a-f]+>/
+    m.to_s.should =~ /\A#<Module:0x\h+>\z/
   end
 
   it "works with an anonymous class" do
     c = Class.new
-    c.to_s.should =~ /#<Class:0x[0-9a-f]+>/
+    c.to_s.should =~ /\A#<Class:0x\h+>\z/
+  end
+
+  it 'for the singleton class of an object of an anonymous class' do
+    klass = Class.new
+    obj = klass.new
+    sclass = obj.singleton_class
+    sclass.to_s.should == "#<Class:#{obj}>"
+    sclass.to_s.should =~ /\A#<Class:#<#{klass}:0x\h+>>\z/
+    sclass.to_s.should =~ /\A#<Class:#<#<Class:0x\h+>:0x\h+>>\z/
+  end
+
+  it 'for a singleton class of a module includes the module name' do
+    ModuleSpecs.singleton_class.to_s.should == '#<Class:ModuleSpecs>'
+  end
+
+  it 'for a metaclass includes the class name' do
+    ModuleSpecs::NamedClass.singleton_class.to_s.should == '#<Class:ModuleSpecs::NamedClass>'
+  end
+
+  it 'for objects includes class name and object ID' do
+    obj = ModuleSpecs::NamedClass.new
+    obj.singleton_class.to_s.should =~ /\A#<Class:#<ModuleSpecs::NamedClass:0x\h+>>\z/
+  end
+
+  it "always show the refinement name, even if the module is named" do
+    module ModuleSpecs::RefinementInspect
+      R = refine String do
+      end
+    end
+
+    ModuleSpecs::RefinementInspect::R.name.should == 'ModuleSpecs::RefinementInspect::R'
+    ModuleSpecs::RefinementInspect::R.to_s.should == '#<refinement:String@ModuleSpecs::RefinementInspect>'
+  ensure
+    ModuleSpecs.send(:remove_const, :RefinementInspect)
+  end
+
+  it 'does not call #inspect or #to_s for singleton classes' do
+    klass = Class.new
+    obj = klass.new
+    def obj.to_s
+      "to_s"
+    end
+    def obj.inspect
+      "inspect"
+    end
+    sclass = obj.singleton_class
+    sclass.to_s.should =~ /\A#<Class:#<#{Regexp.escape klass.to_s}:0x\h+>>\z/
   end
 end
diff --git a/spec/ruby/core/module/undef_method_spec.rb b/spec/ruby/core/module/undef_method_spec.rb
index 9b2c9240f4..d77640cb7e 100644
--- a/spec/ruby/core/module/undef_method_spec.rb
+++ b/spec/ruby/core/module/undef_method_spec.rb
@@ -18,15 +18,8 @@ describe "Module#undef_method" do
     @module = Module.new { def method_to_undef; end }
   end
 
-  ruby_version_is ''...'2.5' do
-    it "is a private method" do
-      Module.should have_private_instance_method(:undef_method, false)
-    end
-  end
-  ruby_version_is '2.5' do
-    it "is a public method" do
-      Module.should have_public_instance_method(:undef_method, false)
-    end
+  it "is a public method" do
+    Module.public_instance_methods(false).should.include?(:undef_method)
   end
 
   it "requires multiple arguments" do
@@ -41,8 +34,8 @@ describe "Module#undef_method" do
     x = klass.new
     klass.send(:undef_method, :method_to_undef, :another_method_to_undef)
 
-    -> { x.method_to_undef }.should raise_error(NoMethodError)
-    -> { x.another_method_to_undef }.should raise_error(NoMethodError)
+    -> { x.method_to_undef }.should.raise(NoMethodError)
+    -> { x.another_method_to_undef }.should.raise(NoMethodError)
   end
 
   it "does not undef any instance methods when argument not given" do
@@ -53,11 +46,40 @@ describe "Module#undef_method" do
   end
 
   it "returns self" do
-    @module.send(:undef_method, :method_to_undef).should equal(@module)
+    @module.send(:undef_method, :method_to_undef).should.equal?(@module)
+  end
+
+  it "raises a NameError when passed a missing name for a module" do
+    -> { @module.send :undef_method, :not_exist }.should.raise(NameError, /undefined method [`']not_exist' for module [`']#{@module}'/) { |e|
+      # a NameError and not a NoMethodError
+      e.class.should == NameError
+    }
+  end
+
+  it "raises a NameError when passed a missing name for a class" do
+    klass = Class.new
+    -> { klass.send :undef_method, :not_exist }.should.raise(NameError, /undefined method [`']not_exist' for class [`']#{klass}'/) { |e|
+      # a NameError and not a NoMethodError
+      e.class.should == NameError
+    }
+  end
+
+  it "raises a NameError when passed a missing name for a singleton class" do
+    klass = Class.new
+    obj = klass.new
+    sclass = obj.singleton_class
+
+    -> { sclass.send :undef_method, :not_exist }.should.raise(NameError, /undefined method [`']not_exist' for class [`']#{sclass}'/) { |e|
+      e.message.should =~ /[`']#<Class:#<#<Class:/
+
+      # a NameError and not a NoMethodError
+      e.class.should == NameError
+    }
   end
 
-  it "raises a NameError when passed a missing name" do
-    -> { @module.send :undef_method, :not_exist }.should raise_error(NameError) { |e|
+  it "raises a NameError when passed a missing name for a metaclass" do
+    klass = String.singleton_class
+    -> { klass.send :undef_method, :not_exist }.should.raise(NameError, /undefined method [`']not_exist' for class [`']String'/) { |e|
       # a NameError and not a NoMethodError
       e.class.should == NameError
     }
@@ -68,20 +90,20 @@ describe "Module#undef_method" do
       @frozen = @module.dup.freeze
     end
 
-    it "raises a #{frozen_error_class} when passed a name" do
-      -> { @frozen.send :undef_method, :method_to_undef }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed a name" do
+      -> { @frozen.send :undef_method, :method_to_undef }.should.raise(FrozenError)
     end
 
-    it "raises a #{frozen_error_class} when passed a missing name" do
-      -> { @frozen.send :undef_method, :not_exist }.should raise_error(frozen_error_class)
+    it "raises a FrozenError when passed a missing name" do
+      -> { @frozen.send :undef_method, :not_exist }.should.raise(FrozenError)
     end
 
     it "raises a TypeError when passed a not name" do
-      -> { @frozen.send :undef_method, Object.new }.should raise_error(TypeError)
+      -> { @frozen.send :undef_method, Object.new }.should.raise(TypeError)
     end
 
     it "does not raise exceptions when no arguments given" do
-      @frozen.send(:undef_method).should equal(@frozen)
+      @frozen.send(:undef_method).should.equal?(@frozen)
     end
   end
 end
@@ -98,7 +120,7 @@ describe "Module#undef_method with symbol" do
 
     klass.send :undef_method, :method_to_undef
 
-    -> { x.method_to_undef }.should raise_error(NoMethodError)
+    -> { x.method_to_undef }.should.raise(NoMethodError)
   end
 
   it "removes a method defined in a super class" do
@@ -108,7 +130,7 @@ describe "Module#undef_method with symbol" do
 
     child_class.send :undef_method, :method_to_undef
 
-    -> { child.method_to_undef }.should raise_error(NoMethodError)
+    -> { child.method_to_undef }.should.raise(NoMethodError)
   end
 
   it "does not remove a method defined in a super class when removed from a subclass" do
@@ -134,7 +156,7 @@ describe "Module#undef_method with string" do
 
     klass.send :undef_method, 'another_method_to_undef'
 
-    -> { x.another_method_to_undef }.should raise_error(NoMethodError)
+    -> { x.another_method_to_undef }.should.raise(NoMethodError)
   end
 
   it "removes a method defined in a super class" do
@@ -144,7 +166,7 @@ describe "Module#undef_method with string" do
 
     child_class.send :undef_method, 'another_method_to_undef'
 
-    -> { child.another_method_to_undef }.should raise_error(NoMethodError)
+    -> { child.another_method_to_undef }.should.raise(NoMethodError)
   end
 
   it "does not remove a method defined in a super class when removed from a subclass" do
diff --git a/spec/ruby/core/module/undefined_instance_methods_spec.rb b/spec/ruby/core/module/undefined_instance_methods_spec.rb
new file mode 100644
index 0000000000..9f731c6adf
--- /dev/null
+++ b/spec/ruby/core/module/undefined_instance_methods_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#undefined_instance_methods" do
+  it "returns methods undefined in the class" do
+    methods = ModuleSpecs::UndefinedInstanceMethods::Parent.undefined_instance_methods
+    methods.should == [:undefed_method]
+  end
+
+  it "returns inherited methods undefined in the class" do
+    methods = ModuleSpecs::UndefinedInstanceMethods::Child.undefined_instance_methods
+    methods.to_set.should >= Set[:parent_method, :another_parent_method]
+  end
+
+  it "returns methods from an included module that are undefined in the class" do
+    methods = ModuleSpecs::UndefinedInstanceMethods::Grandchild.undefined_instance_methods
+    methods.should.include?(:super_included_method)
+  end
+
+  it "does not returns ancestors undefined methods" do
+    methods = ModuleSpecs::UndefinedInstanceMethods::Grandchild.undefined_instance_methods
+    methods.should_not.include?(:parent_method)
+    methods.should_not.include?(:another_parent_method)
+  end
+end
diff --git a/spec/ruby/core/module/used_refinements_spec.rb b/spec/ruby/core/module/used_refinements_spec.rb
new file mode 100644
index 0000000000..40dd4a444e
--- /dev/null
+++ b/spec/ruby/core/module/used_refinements_spec.rb
@@ -0,0 +1,85 @@
+require_relative '../../spec_helper'
+
+describe "Module.used_refinements" do
+  it "returns list of all refinements imported in the current scope" do
+    refinement_int = nil
+    refinement_str = nil
+    ScratchPad.record []
+
+    m1 = Module.new do
+      refine Integer do
+        refinement_int = self
+      end
+    end
+
+    m2 = Module.new do
+      refine String do
+        refinement_str = self
+      end
+    end
+
+    Module.new do
+      using m1
+      using m2
+
+      Module.used_refinements.each { |r| ScratchPad << r }
+    end
+
+    ScratchPad.recorded.sort_by(&:object_id).should == [refinement_int, refinement_str].sort_by(&:object_id)
+  end
+
+  it "returns empty array if does not have any refinements imported" do
+    used_refinements = nil
+
+    Module.new do
+      used_refinements = Module.used_refinements
+    end
+
+    used_refinements.should == []
+  end
+
+  it "ignores refinements imported in a module that is included into the current one" do
+    used_refinements = nil
+
+    m1 = Module.new do
+      refine Integer do
+        nil
+      end
+    end
+
+    m2 = Module.new do
+      using m1
+    end
+
+    Module.new do
+      include m2
+
+      used_refinements = Module.used_refinements
+    end
+
+    used_refinements.should == []
+  end
+
+  it "returns refinements even not defined directly in a module refinements are imported from" do
+    used_refinements = nil
+    ScratchPad.record []
+
+    m1 = Module.new do
+      refine Integer do
+        ScratchPad << self
+      end
+    end
+
+    m2 = Module.new do
+      include m1
+    end
+
+    Module.new do
+      using m2
+
+      used_refinements = Module.used_refinements
+    end
+
+    used_refinements.should == ScratchPad.recorded
+  end
+end
diff --git a/spec/ruby/core/module/using_spec.rb b/spec/ruby/core/module/using_spec.rb
index 533d87d080..cff0edef28 100644
--- a/spec/ruby/core/module/using_spec.rb
+++ b/spec/ruby/core/module/using_spec.rb
@@ -28,7 +28,7 @@ describe "Module#using" do
       Module.new do
         using refinement
       end
-    }.should_not raise_error
+    }.should_not.raise
   end
 
   it "accepts module without refinements" do
@@ -38,7 +38,7 @@ describe "Module#using" do
       Module.new do
         using mod
       end
-    }.should_not raise_error
+    }.should_not.raise
   end
 
   it "does not accept class" do
@@ -48,7 +48,7 @@ describe "Module#using" do
       Module.new do
         using klass
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises TypeError if passed something other than module" do
@@ -56,7 +56,7 @@ describe "Module#using" do
       Module.new do
         using "foo"
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "returns self" do
@@ -67,7 +67,7 @@ describe "Module#using" do
       result = using refinement
     end
 
-    result.should equal(mod)
+    result.should.equal?(mod)
   end
 
   it "works in classes too" do
@@ -95,7 +95,7 @@ describe "Module#using" do
 
     -> {
       mod.foo
-    }.should raise_error(RuntimeError, /Module#using is not permitted in methods/)
+    }.should.raise(RuntimeError, /Module#using is not permitted in methods/)
   end
 
   it "activates refinement even for existed objects" do
@@ -243,6 +243,96 @@ describe "Module#using" do
       mod.call_foo(c).should == "foo from refinement"
     end
 
+    it "is active for module defined via Module.new {}" do
+      refinement = Module.new do
+        refine Integer do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      result = nil
+
+      Module.new do
+        using refinement
+
+        Module.new do
+          result = 1.foo
+        end
+      end
+
+      result.should == "foo from refinement"
+    end
+
+    it "is active for class defined via Class.new {}" do
+      refinement = Module.new do
+        refine Integer do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      result = nil
+
+      Module.new do
+        using refinement
+
+        Class.new do
+          result = 1.foo
+        end
+      end
+
+      result.should == "foo from refinement"
+    end
+
+    it "is active for block called via instance_exec" do
+      refinement = Module.new do
+        refine Integer do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      c = Class.new do
+        using refinement
+
+        def abc
+          block = -> {
+            1.foo
+          }
+
+          self.instance_exec(&block)
+        end
+      end
+
+      c.new.abc.should == "foo from refinement"
+    end
+
+    it "is active for block called via instance_eval" do
+      refinement = Module.new do
+        refine String do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      c = Class.new do
+        using refinement
+
+        def initialize
+          @a = +"1703"
+
+          @a.instance_eval do
+            def abc
+              "#{self}: #{self.foo}"
+            end
+          end
+        end
+
+        def abc
+          @a.abc
+        end
+      end
+
+      c.new.abc.should == "1703: foo from refinement"
+    end
+
     it "is not active if `using` call is not evaluated" do
       result = nil
 
diff --git a/spec/ruby/core/mutex/lock_spec.rb b/spec/ruby/core/mutex/lock_spec.rb
index 7a39817b11..4fee29091a 100644
--- a/spec/ruby/core/mutex/lock_spec.rb
+++ b/spec/ruby/core/mutex/lock_spec.rb
@@ -1,10 +1,6 @@
 require_relative '../../spec_helper'
 
 describe "Mutex#lock" do
-  before :each do
-    ScratchPad.clear
-  end
-
   it "returns self" do
     m = Mutex.new
     m.lock.should == m
@@ -24,11 +20,73 @@ describe "Mutex#lock" do
 
   # Unable to find a specific ticket but behavior change may be
   # related to this ML thread.
-  it "raises a ThreadError when used recursively" do
+  it "raises a deadlock ThreadError when used recursively" do
     m = Mutex.new
     m.lock
     -> {
       m.lock
-    }.should raise_error(ThreadError)
+    }.should.raise(ThreadError, /deadlock/)
+  end
+
+  it "raises a deadlock ThreadError when multiple fibers from the same thread try to lock" do
+    m = Mutex.new
+
+    m.lock
+    f0 = Fiber.new do
+      m.lock
+    end
+    -> { f0.resume }.should.raise(ThreadError, /deadlock/)
+
+    m.unlock
+    f1 = Fiber.new do
+      m.lock
+      Fiber.yield
+    end
+    f2 = Fiber.new do
+      m.lock
+    end
+    f1.resume
+    -> { f2.resume }.should.raise(ThreadError, /deadlock/)
+  end
+
+  it "does not raise deadlock if a fiber's attempt to lock was interrupted" do
+    lock = Mutex.new
+    main = Thread.current
+
+    t2 = nil
+    t1 = Thread.new do
+      loop do
+        # interrupt fiber below looping on synchronize
+        sleep 0.01
+        t2.raise if t2
+      end
+    end
+
+    # loop ten times to try to handle the interrupt during synchronize
+    t2 = Thread.new do
+      10.times do
+        Fiber.new do
+          begin
+            loop { lock.synchronize {} }
+          rescue RuntimeError
+          end
+        end.resume
+
+        Fiber.new do
+          -> do
+            lock.synchronize {}
+          end.should_not.raise(ThreadError)
+        end.resume
+      rescue RuntimeError
+        retry
+      end
+    end
+    t2.join
+  ensure
+    t1.kill rescue nil
+    t2.kill rescue nil
+
+    t1.join
+    t2.join
   end
 end
diff --git a/spec/ruby/core/mutex/locked_spec.rb b/spec/ruby/core/mutex/locked_spec.rb
index 1bf3ed6394..1818cdb4f3 100644
--- a/spec/ruby/core/mutex/locked_spec.rb
+++ b/spec/ruby/core/mutex/locked_spec.rb
@@ -4,12 +4,12 @@ describe "Mutex#locked?" do
   it "returns true if locked" do
     m = Mutex.new
     m.lock
-    m.locked?.should be_true
+    m.locked?.should == true
   end
 
   it "returns false if unlocked" do
     m = Mutex.new
-    m.locked?.should be_false
+    m.locked?.should == false
   end
 
   it "returns the status of the lock" do
@@ -27,10 +27,10 @@ describe "Mutex#locked?" do
 
     Thread.pass until m1_locked
 
-    m1.locked?.should be_true
+    m1.locked?.should == true
     m2.unlock # release th
     th.join
     # A Thread releases its locks upon termination
-    m1.locked?.should be_false
+    m1.locked?.should == false
   end
 end
diff --git a/spec/ruby/core/mutex/owned_spec.rb b/spec/ruby/core/mutex/owned_spec.rb
index e66062534e..ea7d5faf1c 100644
--- a/spec/ruby/core/mutex/owned_spec.rb
+++ b/spec/ruby/core/mutex/owned_spec.rb
@@ -4,7 +4,7 @@ describe "Mutex#owned?" do
   describe "when unlocked" do
     it "returns false" do
       m = Mutex.new
-      m.owned?.should be_false
+      m.owned?.should == false
     end
   end
 
@@ -12,7 +12,7 @@ describe "Mutex#owned?" do
     it "returns true" do
       m = Mutex.new
       m.lock
-      m.owned?.should be_true
+      m.owned?.should == true
     end
   end
 
@@ -37,7 +37,17 @@ describe "Mutex#owned?" do
       end
 
       Thread.pass until locked
-      m.owned?.should be_false
+      m.owned?.should == false
     end
   end
+
+  it "is held per Fiber" do
+    m = Mutex.new
+    m.lock
+
+    Fiber.new do
+      m.locked?.should == true
+      m.owned?.should == false
+    end.resume
+  end
 end
diff --git a/spec/ruby/core/mutex/sleep_spec.rb b/spec/ruby/core/mutex/sleep_spec.rb
index 477f9278c8..71b089d251 100644
--- a/spec/ruby/core/mutex/sleep_spec.rb
+++ b/spec/ruby/core/mutex/sleep_spec.rb
@@ -4,32 +4,32 @@ describe "Mutex#sleep" do
   describe "when not locked by the current thread" do
     it "raises a ThreadError" do
       m = Mutex.new
-      -> { m.sleep }.should raise_error(ThreadError)
+      -> { m.sleep }.should.raise(ThreadError)
     end
 
     it "raises an ArgumentError if passed a negative duration" do
       m = Mutex.new
-      -> { m.sleep(-0.1) }.should raise_error(ArgumentError)
-      -> { m.sleep(-1) }.should raise_error(ArgumentError)
+      -> { m.sleep(-0.1) }.should.raise(ArgumentError)
+      -> { m.sleep(-1) }.should.raise(ArgumentError)
     end
   end
 
   it "raises an ArgumentError if passed a negative duration" do
     m = Mutex.new
     m.lock
-    -> { m.sleep(-0.1) }.should raise_error(ArgumentError)
-    -> { m.sleep(-1) }.should raise_error(ArgumentError)
+    -> { m.sleep(-0.1) }.should.raise(ArgumentError)
+    -> { m.sleep(-1) }.should.raise(ArgumentError)
   end
 
   it "pauses execution for approximately the duration requested" do
     m = Mutex.new
     m.lock
-    duration = 0.1
+    duration = 0.001
     start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     m.sleep duration
     now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-    (now - start).should > 0
-    (now - start).should < 2.0
+    (now - start).should >= 0
+    (now - start).should < (duration + TIME_TOLERANCE)
   end
 
   it "unlocks the mutex while sleeping" do
@@ -37,8 +37,8 @@ describe "Mutex#sleep" do
     locked = false
     th = Thread.new { m.lock; locked = true; m.sleep }
     Thread.pass until locked
-    Thread.pass while th.status and th.status != "sleep"
-    m.locked?.should be_false
+    Thread.pass until th.stop?
+    m.locked?.should == false
     th.run
     th.join
   end
@@ -46,8 +46,8 @@ describe "Mutex#sleep" do
   it "relocks the mutex when woken" do
     m = Mutex.new
     m.lock
-    m.sleep(0.01)
-    m.locked?.should be_true
+    m.sleep(0.001)
+    m.locked?.should == true
   end
 
   it "relocks the mutex when woken by an exception being raised" do
@@ -63,15 +63,31 @@ describe "Mutex#sleep" do
       end
     end
     Thread.pass until locked
-    Thread.pass while th.status and th.status != "sleep"
+    Thread.pass until th.stop?
     th.raise(Exception)
-    th.value.should be_true
+    th.value.should == true
   end
 
   it "returns the rounded number of seconds asleep" do
     m = Mutex.new
-    m.lock
-    m.sleep(0.01).should be_kind_of(Integer)
+    locked = false
+    th = Thread.start do
+      m.lock
+      locked = true
+      m.sleep
+    end
+    Thread.pass until locked
+    Thread.pass until th.stop?
+    th.wakeup
+    th.value.should.is_a?(Integer)
+  end
+
+  it "accepts nil as a sleep duration" do
+    m = Mutex.new
+    -> {
+      m.lock
+      m.sleep(nil)
+    }.should block_caller
   end
 
   it "wakes up when requesting sleep times near or equal to zero" do
@@ -89,7 +105,7 @@ describe "Mutex#sleep" do
     m.lock
     times.each do |time|
       # just testing that sleep completes
-      m.sleep(time).should_not == nil
+      -> {m.sleep(time)}.should_not.raise
     end
   end
 end
diff --git a/spec/ruby/core/mutex/synchronize_spec.rb b/spec/ruby/core/mutex/synchronize_spec.rb
index 7942885197..823f29a634 100644
--- a/spec/ruby/core/mutex/synchronize_spec.rb
+++ b/spec/ruby/core/mutex/synchronize_spec.rb
@@ -14,15 +14,15 @@ describe "Mutex#synchronize" do
           m2.lock
           raise Exception
         end
-      end.should raise_error(Exception)
+      end.should.raise(Exception)
     end
 
     Thread.pass until synchronized
 
-    m1.locked?.should be_true
+    m1.locked?.should == true
     m2.unlock
     th.join
-    m1.locked?.should be_false
+    m1.locked?.should == false
   end
 
   it "blocks the caller if already locked" do
@@ -60,7 +60,7 @@ describe "Mutex#synchronize" do
     m = Mutex.new
 
     m.synchronize do
-      -> { m.synchronize { } }.should raise_error(ThreadError)
+      -> { m.synchronize { } }.should.raise(ThreadError)
     end
   end
 end
diff --git a/spec/ruby/core/mutex/try_lock_spec.rb b/spec/ruby/core/mutex/try_lock_spec.rb
index 8d521f4c6b..1da0735d6a 100644
--- a/spec/ruby/core/mutex/try_lock_spec.rb
+++ b/spec/ruby/core/mutex/try_lock_spec.rb
@@ -4,13 +4,13 @@ describe "Mutex#try_lock" do
   describe "when unlocked" do
     it "returns true" do
       m = Mutex.new
-      m.try_lock.should be_true
+      m.try_lock.should == true
     end
 
     it "locks the mutex" do
       m = Mutex.new
       m.try_lock
-      m.locked?.should be_true
+      m.locked?.should == true
     end
   end
 
@@ -18,7 +18,7 @@ describe "Mutex#try_lock" do
     it "returns false" do
       m = Mutex.new
       m.lock
-      m.try_lock.should be_false
+      m.try_lock.should == false
     end
   end
 
@@ -26,7 +26,7 @@ describe "Mutex#try_lock" do
     it "returns false" do
       m = Mutex.new
       m.lock
-      Thread.new { m.try_lock }.value.should be_false
+      Thread.new { m.try_lock }.value.should == false
     end
   end
 end
diff --git a/spec/ruby/core/mutex/unlock_spec.rb b/spec/ruby/core/mutex/unlock_spec.rb
index c9c3bfe14f..ed493cf84a 100644
--- a/spec/ruby/core/mutex/unlock_spec.rb
+++ b/spec/ruby/core/mutex/unlock_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Mutex#unlock" do
   it "raises ThreadError unless Mutex is locked" do
     mutex = Mutex.new
-    -> { mutex.unlock }.should raise_error(ThreadError)
+    -> { mutex.unlock }.should.raise(ThreadError)
   end
 
   it "raises ThreadError unless thread owns Mutex" do
@@ -17,9 +17,9 @@ describe "Mutex#unlock" do
 
     # avoid race on mutex.lock
     Thread.pass until mutex.locked?
-    Thread.pass while th.status and th.status != "sleep"
+    Thread.pass until th.stop?
 
-    -> { mutex.unlock }.should raise_error(ThreadError)
+    -> { mutex.unlock }.should.raise(ThreadError)
 
     wait.unlock
     th.join
@@ -33,6 +33,6 @@ describe "Mutex#unlock" do
 
     th.join
 
-    -> { mutex.unlock }.should raise_error(ThreadError)
+    -> { mutex.unlock }.should.raise(ThreadError)
   end
 end
diff --git a/spec/ruby/core/nil/case_compare_spec.rb b/spec/ruby/core/nil/case_compare_spec.rb
new file mode 100644
index 0000000000..142560c6f5
--- /dev/null
+++ b/spec/ruby/core/nil/case_compare_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "NilClass#===" do
+  it "returns true for nil" do
+    (nil === nil).should == true
+  end
+
+  it "returns false for non-nil object" do
+    (nil === 1).should == false
+    (nil === "").should == false
+    (nil === Object).should == false
+  end
+end
diff --git a/spec/ruby/core/nil/dup_spec.rb b/spec/ruby/core/nil/dup_spec.rb
index 0324b3f1f4..e0be9540a6 100644
--- a/spec/ruby/core/nil/dup_spec.rb
+++ b/spec/ruby/core/nil/dup_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#dup" do
   it "returns self" do
-    nil.dup.should equal(nil)
+    nil.dup.should.equal?(nil)
   end
 end
diff --git a/spec/ruby/core/nil/match_spec.rb b/spec/ruby/core/nil/match_spec.rb
index 3f69312bfe..27ebc53c3d 100644
--- a/spec/ruby/core/nil/match_spec.rb
+++ b/spec/ruby/core/nil/match_spec.rb
@@ -1,19 +1,21 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "NilClass#=~" do
-    it "returns nil matching any object" do
-      o = Object.new
+describe "NilClass#=~" do
+  it "returns nil matching any object" do
+    o = nil
 
-      suppress_warning do
-        (o =~ /Object/).should   be_nil
-        (o =~ 'Object').should   be_nil
-        (o =~ Object).should     be_nil
-        (o =~ Object.new).should be_nil
-        (o =~ nil).should        be_nil
-        (o =~ false).should      be_nil
-        (o =~ true).should       be_nil
-      end
+    suppress_warning do
+      (o =~ /Object/).should == nil
+      (o =~ 'Object').should == nil
+      (o =~ Object).should == nil
+      (o =~ Object.new).should == nil
+      (o =~ nil).should == nil
+      (o =~ false).should == nil
+      (o =~ true).should == nil
     end
   end
+
+  it "should not warn" do
+    -> { nil =~ /a/ }.should_not complain(verbose: true)
+  end
 end
diff --git a/spec/ruby/core/nil/nil_spec.rb b/spec/ruby/core/nil/nil_spec.rb
index 47db0c5cf0..2cf97621c6 100644
--- a/spec/ruby/core/nil/nil_spec.rb
+++ b/spec/ruby/core/nil/nil_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#nil?" do
   it "returns true" do
-    nil.nil?.should == true
+    nil.should.nil?
   end
 end
diff --git a/spec/ruby/core/nil/nilclass_spec.rb b/spec/ruby/core/nil/nilclass_spec.rb
index 7f6d8af25d..55c5d0eba7 100644
--- a/spec/ruby/core/nil/nilclass_spec.rb
+++ b/spec/ruby/core/nil/nilclass_spec.rb
@@ -4,12 +4,12 @@ describe "NilClass" do
   it ".allocate raises a TypeError" do
     -> do
       NilClass.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       NilClass.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/nil/rationalize_spec.rb b/spec/ruby/core/nil/rationalize_spec.rb
index 84d6e6f056..69fb257a7f 100644
--- a/spec/ruby/core/nil/rationalize_spec.rb
+++ b/spec/ruby/core/nil/rationalize_spec.rb
@@ -10,7 +10,7 @@ describe "NilClass#rationalize" do
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { nil.rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { nil.rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { nil.rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { nil.rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/nil/singleton_method_spec.rb b/spec/ruby/core/nil/singleton_method_spec.rb
new file mode 100644
index 0000000000..f121b42f81
--- /dev/null
+++ b/spec/ruby/core/nil/singleton_method_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "NilClass#singleton_method" do
+  it "raises regardless of whether NilClass defines the method" do
+    -> { nil.singleton_method(:foo) }.should.raise(NameError)
+    begin
+      def (nil).foo; end
+      -> { nil.singleton_method(:foo) }.should.raise(NameError)
+    ensure
+      NilClass.send(:remove_method, :foo)
+    end
+  end
+end
diff --git a/spec/ruby/core/nil/to_c_spec.rb b/spec/ruby/core/nil/to_c_spec.rb
index e0052be5bd..f449ddb6a3 100644
--- a/spec/ruby/core/nil/to_c_spec.rb
+++ b/spec/ruby/core/nil/to_c_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#to_c" do
   it "returns Complex(0, 0)" do
-    nil.to_c.should eql(Complex(0, 0))
+    nil.to_c.should.eql?(Complex(0, 0))
   end
 end
diff --git a/spec/ruby/core/nil/to_i_spec.rb b/spec/ruby/core/nil/to_i_spec.rb
index 099792ef68..d3d088e999 100644
--- a/spec/ruby/core/nil/to_i_spec.rb
+++ b/spec/ruby/core/nil/to_i_spec.rb
@@ -5,7 +5,7 @@ describe "NilClass#to_i" do
     nil.to_i.should == 0
   end
 
-  it "does not cause NilClass to be coerced to Fixnum" do
+  it "does not cause NilClass to be coerced to Integer" do
     (0 == nil).should == false
   end
 end
diff --git a/spec/ruby/core/nil/to_s_spec.rb b/spec/ruby/core/nil/to_s_spec.rb
index 4b61f589f7..016ba4165a 100644
--- a/spec/ruby/core/nil/to_s_spec.rb
+++ b/spec/ruby/core/nil/to_s_spec.rb
@@ -5,13 +5,11 @@ describe "NilClass#to_s" do
     nil.to_s.should == ""
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen string" do
-      nil.to_s.frozen?.should == true
-    end
+  it "returns a frozen string" do
+    nil.to_s.should.frozen?
+  end
 
-    it "always returns the same string" do
-      nil.to_s.should equal(nil.to_s)
-    end
+  it "always returns the same string" do
+    nil.to_s.should.equal?(nil.to_s)
   end
 end
diff --git a/spec/ruby/core/numeric/abs2_spec.rb b/spec/ruby/core/numeric/abs2_spec.rb
index 0e60cd0ae7..12866f9c47 100644
--- a/spec/ruby/core/numeric/abs2_spec.rb
+++ b/spec/ruby/core/numeric/abs2_spec.rb
@@ -18,7 +18,7 @@ describe "Numeric#abs2" do
 
   it "returns the square of the absolute value of self" do
     @numbers.each do |number|
-      number.abs2.should eql(number.abs ** 2)
+      number.abs2.should.eql?(number.abs ** 2)
     end
   end
 
@@ -29,6 +29,6 @@ describe "Numeric#abs2" do
   end
 
   it "returns NaN when self is NaN" do
-    nan_value.abs2.nan?.should be_true
+    nan_value.abs2.nan?.should == true
   end
 end
diff --git a/spec/ruby/core/numeric/clone_spec.rb b/spec/ruby/core/numeric/clone_spec.rb
new file mode 100644
index 0000000000..1d06fdb050
--- /dev/null
+++ b/spec/ruby/core/numeric/clone_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+
+describe "Numeric#clone" do
+  it "returns self" do
+    value = 1
+    value.clone.should.equal?(value)
+
+    subclass = Class.new(Numeric)
+    value = subclass.new
+    value.clone.should.equal?(value)
+  end
+
+  it "does not change frozen status" do
+    1.clone.frozen?.should == true
+  end
+
+  it "accepts optional keyword argument :freeze" do
+    value = 1
+    value.clone(freeze: true).should.equal?(value)
+  end
+
+  it "raises ArgumentError if passed freeze: false" do
+    -> { 1.clone(freeze: false) }.should.raise(ArgumentError, /can't unfreeze/)
+  end
+
+  it "does not change frozen status if passed freeze: nil" do
+    value = 1
+    value.clone(freeze: nil).should.equal?(value)
+  end
+end
diff --git a/spec/ruby/core/numeric/coerce_spec.rb b/spec/ruby/core/numeric/coerce_spec.rb
index 4c4416d30b..9344d99ee6 100644
--- a/spec/ruby/core/numeric/coerce_spec.rb
+++ b/spec/ruby/core/numeric/coerce_spec.rb
@@ -25,7 +25,7 @@ describe "Numeric#coerce" do
       class << a; true; end
 
       # watch it explode
-      -> { a.coerce(b) }.should raise_error(TypeError)
+      -> { a.coerce(b) }.should.raise(TypeError)
     end
   end
 
@@ -38,22 +38,22 @@ describe "Numeric#coerce" do
 
   it "raise TypeError if they are instances of different classes and other does not respond to #to_f" do
     other = mock("numeric")
-    -> { @obj.coerce(other)   }.should raise_error(TypeError)
+    -> { @obj.coerce(other)   }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { @obj.coerce(nil)     }.should raise_error(TypeError)
+    -> { @obj.coerce(nil)     }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a boolean" do
-    -> { @obj.coerce(false)   }.should raise_error(TypeError)
+    -> { @obj.coerce(false)   }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a Symbol" do
-    -> { @obj.coerce(:symbol) }.should raise_error(TypeError)
+    -> { @obj.coerce(:symbol) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when passed a non-numeric String" do
-    -> { @obj.coerce("test")  }.should raise_error(ArgumentError)
+    -> { @obj.coerce("test")  }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/numeric/comparison_spec.rb b/spec/ruby/core/numeric/comparison_spec.rb
index 4b4d52501a..b0a9390cc0 100644
--- a/spec/ruby/core/numeric/comparison_spec.rb
+++ b/spec/ruby/core/numeric/comparison_spec.rb
@@ -26,22 +26,22 @@ describe "Numeric#<=>" do
     end
 
     it "is called when instances are compared with #<" do
-      (@a < @b).should be_false
+      (@a < @b).should == false
       ScratchPad.recorded.should == :numeric_comparison
     end
 
     it "is called when instances are compared with #<=" do
-      (@a <= @b).should be_false
+      (@a <= @b).should == false
       ScratchPad.recorded.should == :numeric_comparison
     end
 
     it "is called when instances are compared with #>" do
-      (@a > @b).should be_true
+      (@a > @b).should == true
       ScratchPad.recorded.should == :numeric_comparison
     end
 
     it "is called when instances are compared with #>=" do
-      (@a >= @b).should be_true
+      (@a >= @b).should == true
       ScratchPad.recorded.should == :numeric_comparison
     end
   end
diff --git a/spec/ruby/core/numeric/div_spec.rb b/spec/ruby/core/numeric/div_spec.rb
index 53917b84c9..a17961850c 100644
--- a/spec/ruby/core/numeric/div_spec.rb
+++ b/spec/ruby/core/numeric/div_spec.rb
@@ -15,8 +15,8 @@ describe "Numeric#div" do
   end
 
   it "raises ZeroDivisionError for 0" do
-    -> { @obj.div(0) }.should raise_error(ZeroDivisionError)
-    -> { @obj.div(0.0) }.should raise_error(ZeroDivisionError)
-    -> { @obj.div(Complex(0,0)) }.should raise_error(ZeroDivisionError)
+    -> { @obj.div(0) }.should.raise(ZeroDivisionError)
+    -> { @obj.div(0.0) }.should.raise(ZeroDivisionError)
+    -> { @obj.div(Complex(0,0)) }.should.raise(ZeroDivisionError)
   end
 end
diff --git a/spec/ruby/core/numeric/dup_spec.rb b/spec/ruby/core/numeric/dup_spec.rb
new file mode 100644
index 0000000000..c158c618de
--- /dev/null
+++ b/spec/ruby/core/numeric/dup_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../spec_helper'
+
+describe "Numeric#dup" do
+  it "returns self" do
+    value = 1
+    value.dup.should.equal?(value)
+
+    subclass = Class.new(Numeric)
+    value = subclass.new
+    value.dup.should.equal?(value)
+  end
+
+  it "does not change frozen status" do
+    1.dup.frozen?.should == true
+  end
+end
diff --git a/spec/ruby/core/numeric/eql_spec.rb b/spec/ruby/core/numeric/eql_spec.rb
index b33e00e51f..80c58caef4 100644
--- a/spec/ruby/core/numeric/eql_spec.rb
+++ b/spec/ruby/core/numeric/eql_spec.rb
@@ -7,16 +7,16 @@ describe "Numeric#eql?" do
   end
 
   it "returns false if self's and other's types don't match" do
-    @obj.should_not eql(1)
-    @obj.should_not eql(-1.5)
-    @obj.should_not eql(bignum_value)
-    @obj.should_not eql(:sym)
+    @obj.should_not.eql?(1)
+    @obj.should_not.eql?(-1.5)
+    @obj.should_not.eql?(bignum_value)
+    @obj.should_not.eql?(:sym)
   end
 
   it "returns the result of calling self#== with other when self's and other's types match" do
     other = NumericSpecs::Subclass.new
     @obj.should_receive(:==).with(other).and_return("result", nil)
-    @obj.should eql(other)
-    @obj.should_not eql(other)
+    @obj.should.eql?(other)
+    @obj.should_not.eql?(other)
   end
 end
diff --git a/spec/ruby/core/numeric/fdiv_spec.rb b/spec/ruby/core/numeric/fdiv_spec.rb
index 907e5d343c..2c22c6a86a 100644
--- a/spec/ruby/core/numeric/fdiv_spec.rb
+++ b/spec/ruby/core/numeric/fdiv_spec.rb
@@ -1,5 +1,4 @@
 require_relative '../../spec_helper'
-require_relative 'shared/quo'
 
 describe "Numeric#fdiv" do
   it "coerces self with #to_f" do
@@ -19,7 +18,7 @@ describe "Numeric#fdiv" do
   end
 
   it "returns a Float" do
-    bignum_value.fdiv(Float::MAX).should be_an_instance_of(Float)
+    bignum_value.fdiv(Float::MAX).should.instance_of?(Float)
   end
 
   it "returns Infinity if other is 0" do
@@ -27,6 +26,6 @@ describe "Numeric#fdiv" do
   end
 
   it "returns NaN if other is NaN" do
-    3334.fdiv(nan_value).nan?.should be_true
+    3334.fdiv(nan_value).nan?.should == true
   end
 end
diff --git a/spec/ruby/core/numeric/finite_spec.rb b/spec/ruby/core/numeric/finite_spec.rb
index 05b5eebbd6..2c18c89466 100644
--- a/spec/ruby/core/numeric/finite_spec.rb
+++ b/spec/ruby/core/numeric/finite_spec.rb
@@ -3,6 +3,6 @@ require_relative '../../spec_helper'
 describe "Numeric#finite?" do
   it "returns true by default" do
     o = mock_numeric("finite")
-    o.finite?.should be_true
+    o.finite?.should == true
   end
 end
diff --git a/spec/ruby/core/numeric/i_spec.rb b/spec/ruby/core/numeric/i_spec.rb
index 621ecc09ec..f5fb99dfd3 100644
--- a/spec/ruby/core/numeric/i_spec.rb
+++ b/spec/ruby/core/numeric/i_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Numeric#i" do
   it "returns a Complex object" do
-    34.i.should be_an_instance_of(Complex)
+    34.i.should.instance_of?(Complex)
   end
 
   it "sets the real part to 0" do
diff --git a/spec/ruby/core/numeric/integer_spec.rb b/spec/ruby/core/numeric/integer_spec.rb
index 5d4bf00360..adbac4d7aa 100644
--- a/spec/ruby/core/numeric/integer_spec.rb
+++ b/spec/ruby/core/numeric/integer_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "Numeric#integer?" do
   it "returns false" do
-    NumericSpecs::Subclass.new.integer?.should == false
+    NumericSpecs::Subclass.new.should_not.integer?
   end
 end
diff --git a/spec/ruby/core/numeric/magnitude_spec.rb b/spec/ruby/core/numeric/magnitude_spec.rb
index 7a3290b036..1371dff21f 100644
--- a/spec/ruby/core/numeric/magnitude_spec.rb
+++ b/spec/ruby/core/numeric/magnitude_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../spec_helper"
 require_relative 'shared/abs'
 
 describe "Numeric#magnitude" do
diff --git a/spec/ruby/core/numeric/negative_spec.rb b/spec/ruby/core/numeric/negative_spec.rb
index da464a9094..f2d8a847da 100644
--- a/spec/ruby/core/numeric/negative_spec.rb
+++ b/spec/ruby/core/numeric/negative_spec.rb
@@ -4,22 +4,22 @@ require_relative 'fixtures/classes'
 describe "Numeric#negative?" do
   describe "on positive numbers" do
     it "returns false" do
-      1.negative?.should be_false
-      0.1.negative?.should be_false
+      1.negative?.should == false
+      0.1.negative?.should == false
     end
   end
 
   describe "on zero" do
     it "returns false" do
-      0.negative?.should be_false
-      0.0.negative?.should be_false
+      0.negative?.should == false
+      0.0.negative?.should == false
     end
   end
 
   describe "on negative numbers" do
     it "returns true" do
-      -1.negative?.should be_true
-      -0.1.negative?.should be_true
+      -1.negative?.should == true
+      -0.1.negative?.should == true
     end
   end
 end
@@ -31,11 +31,11 @@ describe "Numeric#negative?" do
 
   it "returns true if self is less than 0" do
     @obj.should_receive(:<).with(0).and_return(true)
-    @obj.negative?.should == true
+    @obj.should.negative?
   end
 
   it "returns false if self is greater than 0" do
     @obj.should_receive(:<).with(0).and_return(false)
-    @obj.negative?.should == false
+    @obj.should_not.negative?
   end
 end
diff --git a/spec/ruby/core/numeric/polar_spec.rb b/spec/ruby/core/numeric/polar_spec.rb
index b594e408b2..0695d7afb2 100644
--- a/spec/ruby/core/numeric/polar_spec.rb
+++ b/spec/ruby/core/numeric/polar_spec.rb
@@ -17,7 +17,7 @@ describe "Numeric#polar" do
 
   it "returns a two-element Array" do
     @numbers.each do |number|
-      number.polar.should be_an_instance_of(Array)
+      number.polar.should.instance_of?(Array)
       number.polar.size.should == 2
     end
   end
@@ -44,7 +44,7 @@ describe "Numeric#polar" do
 
   it "returns [NaN, NaN] if self is NaN" do
     nan_value.polar.size.should == 2
-    nan_value.polar.first.nan?.should be_true
-    nan_value.polar.last.nan?.should be_true
+    nan_value.polar.first.nan?.should == true
+    nan_value.polar.last.nan?.should == true
   end
 end
diff --git a/spec/ruby/core/numeric/positive_spec.rb b/spec/ruby/core/numeric/positive_spec.rb
index 8f98fbfa26..7c8d15cd9f 100644
--- a/spec/ruby/core/numeric/positive_spec.rb
+++ b/spec/ruby/core/numeric/positive_spec.rb
@@ -4,22 +4,22 @@ require_relative 'fixtures/classes'
 describe "Numeric#positive?" do
   describe "on positive numbers" do
     it "returns true" do
-      1.positive?.should be_true
-      0.1.positive?.should be_true
+      1.positive?.should == true
+      0.1.positive?.should == true
     end
   end
 
   describe "on zero" do
     it "returns false" do
-      0.positive?.should be_false
-      0.0.positive?.should be_false
+      0.positive?.should == false
+      0.0.positive?.should == false
     end
   end
 
   describe "on negative numbers" do
     it "returns false" do
-      -1.positive?.should be_false
-      -0.1.positive?.should be_false
+      -1.positive?.should == false
+      -0.1.positive?.should == false
     end
   end
 end
@@ -31,11 +31,11 @@ describe "Numeric#positive?" do
 
   it "returns true if self is greater than 0" do
     @obj.should_receive(:>).with(0).and_return(true)
-    @obj.positive?.should == true
+    @obj.should.positive?
   end
 
   it "returns false if self is less than 0" do
     @obj.should_receive(:>).with(0).and_return(false)
-    @obj.positive?.should == false
+    @obj.should_not.positive?
   end
 end
diff --git a/spec/ruby/core/numeric/quo_spec.rb b/spec/ruby/core/numeric/quo_spec.rb
index 5c952b11a9..66ff019231 100644
--- a/spec/ruby/core/numeric/quo_spec.rb
+++ b/spec/ruby/core/numeric/quo_spec.rb
@@ -1,14 +1,13 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'shared/quo'
 
 describe "Numeric#quo" do
   it "returns the result of self divided by the given Integer as a Rational" do
-    5.quo(2).should eql(Rational(5,2))
+    5.quo(2).should.eql?(Rational(5,2))
   end
 
   it "returns the result of self divided by the given Float as a Float" do
-    2.quo(2.5).should eql(0.8)
+    2.quo(2.5).should.eql?(0.8)
   end
 
   it "returns the result of self divided by the given Bignum as a Float" do
@@ -16,11 +15,11 @@ describe "Numeric#quo" do
   end
 
   it "raises a ZeroDivisionError when the given Integer is 0" do
-    -> { 0.quo(0) }.should raise_error(ZeroDivisionError)
-    -> { 10.quo(0) }.should raise_error(ZeroDivisionError)
-    -> { -10.quo(0) }.should raise_error(ZeroDivisionError)
-    -> { bignum_value.quo(0) }.should raise_error(ZeroDivisionError)
-    -> { -bignum_value.quo(0) }.should raise_error(ZeroDivisionError)
+    -> { 0.quo(0) }.should.raise(ZeroDivisionError)
+    -> { 10.quo(0) }.should.raise(ZeroDivisionError)
+    -> { -10.quo(0) }.should.raise(ZeroDivisionError)
+    -> { bignum_value.quo(0) }.should.raise(ZeroDivisionError)
+    -> { (-bignum_value).quo(0) }.should.raise(ZeroDivisionError)
   end
 
   it "calls #to_r to convert the object to a Rational" do
@@ -34,16 +33,16 @@ describe "Numeric#quo" do
     obj = NumericSpecs::Subclass.new
     obj.should_receive(:to_r).and_return(1)
 
-    -> { obj.quo(19) }.should raise_error(TypeError)
+    -> { obj.quo(19) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when given a non-Integer" do
     -> {
       (obj = mock('x')).should_not_receive(:to_int)
       13.quo(obj)
-    }.should raise_error(TypeError)
-    -> { 13.quo("10")    }.should raise_error(TypeError)
-    -> { 13.quo(:symbol) }.should raise_error(TypeError)
+    }.should.raise(TypeError)
+    -> { 13.quo("10")    }.should.raise(TypeError)
+    -> { 13.quo(:symbol) }.should.raise(TypeError)
   end
 
   it "returns the result of calling self#/ with other" do
@@ -52,4 +51,13 @@ describe "Numeric#quo" do
 
     obj.quo(19).should == 1.quo(20)
   end
+
+  it "raises a ZeroDivisionError if the given argument is zero and not a Float" do
+    -> { 1.quo(0) }.should.raise(ZeroDivisionError)
+  end
+
+  it "returns infinity if the given argument is zero and is a Float" do
+    (1.quo(0.0)).to_s.should == 'Infinity'
+    (-1.quo(0.0)).to_s.should == '-Infinity'
+  end
 end
diff --git a/spec/ruby/core/numeric/real_spec.rb b/spec/ruby/core/numeric/real_spec.rb
index caa8dcec6d..09d482a691 100644
--- a/spec/ruby/core/numeric/real_spec.rb
+++ b/spec/ruby/core/numeric/real_spec.rb
@@ -16,7 +16,7 @@ describe "Numeric#real" do
   it "returns self" do
     @numbers.each do |number|
       if number.to_f.nan?
-        number.real.nan?.should be_true
+        number.real.nan?.should == true
       else
         number.real.should == number
       end
@@ -25,13 +25,13 @@ describe "Numeric#real" do
 
   it "raises an ArgumentError if given any arguments" do
     @numbers.each do |number|
-      -> { number.real(number) }.should raise_error(ArgumentError)
+      -> { number.real(number) }.should.raise(ArgumentError)
     end
   end
 end
 
 describe "Numeric#real?" do
   it "returns true" do
-    NumericSpecs::Subclass.new.real?.should == true
+    NumericSpecs::Subclass.new.should.real?
   end
 end
diff --git a/spec/ruby/core/numeric/remainder_spec.rb b/spec/ruby/core/numeric/remainder_spec.rb
index 1e2f5f3a96..bdf7358b21 100644
--- a/spec/ruby/core/numeric/remainder_spec.rb
+++ b/spec/ruby/core/numeric/remainder_spec.rb
@@ -6,13 +6,14 @@ describe "Numeric#remainder" do
     @obj    = NumericSpecs::Subclass.new
     @result = mock("Numeric#% result")
     @other  = mock("Passed Object")
+    @other.should_receive(:coerce).with(@obj).and_return([@obj, @other])
   end
 
   it "returns the result of calling self#% with other if self is 0" do
     @obj.should_receive(:%).with(@other).and_return(@result)
     @result.should_receive(:==).with(0).and_return(true)
 
-    @obj.remainder(@other).should equal(@result)
+    @obj.remainder(@other).should.equal?(@result)
   end
 
   it "returns the result of calling self#% with other if self and other are greater than 0" do
@@ -24,7 +25,7 @@ describe "Numeric#remainder" do
     @obj.should_receive(:>).with(0).and_return(true)
     @other.should_receive(:<).with(0).and_return(false)
 
-    @obj.remainder(@other).should equal(@result)
+    @obj.remainder(@other).should.equal?(@result)
   end
 
   it "returns the result of calling self#% with other if self and other are less than 0" do
@@ -36,7 +37,7 @@ describe "Numeric#remainder" do
 
     @obj.should_receive(:>).with(0).and_return(false)
 
-    @obj.remainder(@other).should equal(@result)
+    @obj.remainder(@other).should.equal?(@result)
   end
 
   it "returns the result of calling self#% with other - other if self is greater than 0 and other is less than 0" do
diff --git a/spec/ruby/core/numeric/shared/conj.rb b/spec/ruby/core/numeric/shared/conj.rb
index 6d5197ecab..1a661fbbe8 100644
--- a/spec/ruby/core/numeric/shared/conj.rb
+++ b/spec/ruby/core/numeric/shared/conj.rb
@@ -14,7 +14,7 @@ describe :numeric_conj, shared: true do
 
   it "returns self" do
     @numbers.each do |number|
-      number.send(@method).should equal(number)
+      number.send(@method).should.equal?(number)
     end
   end
 end
diff --git a/spec/ruby/core/numeric/shared/imag.rb b/spec/ruby/core/numeric/shared/imag.rb
index ac2da40a3b..605a23d8c6 100644
--- a/spec/ruby/core/numeric/shared/imag.rb
+++ b/spec/ruby/core/numeric/shared/imag.rb
@@ -19,8 +19,8 @@ describe :numeric_imag, shared: true do
   end
 
   it "raises an ArgumentError if given any arguments" do
-   @numbers.each do |number|
-     -> { number.send(@method, number) }.should raise_error(ArgumentError)
-   end
+    @numbers.each do |number|
+      -> { number.send(@method, number) }.should.raise(ArgumentError)
+    end
   end
 end
diff --git a/spec/ruby/core/numeric/shared/quo.rb b/spec/ruby/core/numeric/shared/quo.rb
deleted file mode 100644
index 2392636fe7..0000000000
--- a/spec/ruby/core/numeric/shared/quo.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-describe :numeric_quo_18, shared: true do
-  it "returns the result of calling self#/ with other" do
-    obj = mock_numeric('numeric')
-    obj.should_receive(:/).with(19).and_return(:result)
-    obj.send(@method, 19).should == :result
-  end
-end
diff --git a/spec/ruby/core/numeric/shared/rect.rb b/spec/ruby/core/numeric/shared/rect.rb
index 9cde19a398..32d03e45d2 100644
--- a/spec/ruby/core/numeric/shared/rect.rb
+++ b/spec/ruby/core/numeric/shared/rect.rb
@@ -14,7 +14,7 @@ describe :numeric_rect, shared: true do
 
   it "returns an Array" do
     @numbers.each do |number|
-      number.send(@method).should be_an_instance_of(Array)
+      number.send(@method).should.instance_of?(Array)
     end
   end
 
@@ -25,24 +25,24 @@ describe :numeric_rect, shared: true do
   end
 
   it "returns self as the first element" do
-   @numbers.each do |number|
-     if Float === number and number.nan?
-       number.send(@method).first.nan?.should be_true
-     else
-       number.send(@method).first.should == number
-     end
-   end
+    @numbers.each do |number|
+      if Float === number and number.nan?
+        number.send(@method).first.nan?.should == true
+      else
+        number.send(@method).first.should == number
+      end
+    end
   end
 
   it "returns 0 as the last element" do
-   @numbers.each do |number|
-     number.send(@method).last.should == 0
-   end
+    @numbers.each do |number|
+      number.send(@method).last.should == 0
+    end
   end
 
   it "raises an ArgumentError if given any arguments" do
-   @numbers.each do |number|
-     -> { number.send(@method, number) }.should raise_error(ArgumentError)
-   end
+    @numbers.each do |number|
+      -> { number.send(@method, number) }.should.raise(ArgumentError)
+    end
   end
 end
diff --git a/spec/ruby/core/numeric/shared/step.rb b/spec/ruby/core/numeric/shared/step.rb
index 364d4769ad..66b8c1af0d 100644
--- a/spec/ruby/core/numeric/shared/step.rb
+++ b/spec/ruby/core/numeric/shared/step.rb
@@ -5,7 +5,7 @@ require_relative '../fixtures/classes'
 # To be able to do it, the @step ivar must contain a Proc that transforms
 # the step call arguments passed as positional arguments to the style of
 # arguments pretended to test.
-describe :numeric_step, :shared => true do
+describe :numeric_step, shared: true do
   before :each do
     ScratchPad.record []
     @prc = -> x { ScratchPad << x }
@@ -13,7 +13,7 @@ describe :numeric_step, :shared => true do
 
   it "defaults to step = 1" do
     @step.call(1, 5, &@prc)
-    ScratchPad.recorded.should eql [1, 2, 3, 4, 5]
+    ScratchPad.recorded.should.eql? [1, 2, 3, 4, 5]
   end
 
   it "defaults to an infinite limit with a step size of 1 for Integers" do
@@ -24,37 +24,37 @@ describe :numeric_step, :shared => true do
     1.0.step.first(5).should == [1.0, 2.0, 3.0, 4.0, 5.0]
   end
 
-  describe "when self, stop and step are Fixnums" do
-    it "yields only Fixnums" do
-      @step.call(1, 5, 1) { |x| x.should be_an_instance_of(Fixnum) }
+  describe "when self, stop and step are Integers" do
+    it "yields only Integers" do
+      @step.call(1, 5, 1) { |x| x.should.instance_of?(Integer) }
     end
 
     describe "with a positive step" do
       it "yields while increasing self by step until stop is reached" do
         @step.call(1, 5, 1, &@prc)
-        ScratchPad.recorded.should eql [1, 2, 3, 4, 5]
+        ScratchPad.recorded.should.eql? [1, 2, 3, 4, 5]
       end
 
       it "yields once when self equals stop" do
         @step.call(1, 1, 1, &@prc)
-        ScratchPad.recorded.should eql [1]
+        ScratchPad.recorded.should.eql? [1]
       end
 
       it "does not yield when self is greater than stop" do
         @step.call(2, 1, 1, &@prc)
-        ScratchPad.recorded.should eql []
+        ScratchPad.recorded.should.eql? []
       end
     end
 
     describe "with a negative step" do
       it "yields while decreasing self by step until stop is reached" do
         @step.call(5, 1, -1, &@prc)
-        ScratchPad.recorded.should eql [5, 4, 3, 2, 1]
+        ScratchPad.recorded.should.eql? [5, 4, 3, 2, 1]
       end
 
       it "yields once when self equals stop" do
         @step.call(5, 5, -1, &@prc)
-        ScratchPad.recorded.should eql [5]
+        ScratchPad.recorded.should.eql? [5]
       end
 
       it "does not yield when self is less than stop" do
@@ -66,26 +66,26 @@ describe :numeric_step, :shared => true do
 
   describe "when at least one of self, stop or step is a Float" do
     it "yields Floats even if only self is a Float" do
-      @step.call(1.5, 5, 1) { |x| x.should be_an_instance_of(Float) }
+      @step.call(1.5, 5, 1) { |x| x.should.instance_of?(Float) }
     end
 
     it "yields Floats even if only stop is a Float" do
-      @step.call(1, 5.0, 1) { |x| x.should be_an_instance_of(Float) }
+      @step.call(1, 5.0, 1) { |x| x.should.instance_of?(Float) }
     end
 
     it "yields Floats even if only step is a Float" do
-      @step.call(1, 5, 1.0) { |x| x.should be_an_instance_of(Float) }
+      @step.call(1, 5, 1.0) { |x| x.should.instance_of?(Float) }
     end
 
     describe "with a positive step" do
       it "yields while increasing self by step while < stop" do
         @step.call(1.5, 5, 1, &@prc)
-        ScratchPad.recorded.should eql [1.5, 2.5, 3.5, 4.5]
+        ScratchPad.recorded.should.eql? [1.5, 2.5, 3.5, 4.5]
       end
 
       it "yields once when self equals stop" do
         @step.call(1.5, 1.5, 1, &@prc)
-        ScratchPad.recorded.should eql [1.5]
+        ScratchPad.recorded.should.eql? [1.5]
       end
 
       it "does not yield when self is greater than stop" do
@@ -96,19 +96,19 @@ describe :numeric_step, :shared => true do
       it "is careful about not yielding a value greater than limit" do
         # As 9*1.3+1.0 == 12.700000000000001 > 12.7, we test:
         @step.call(1.0, 12.7, 1.3, &@prc)
-        ScratchPad.recorded.should eql [1.0, 2.3, 3.6, 4.9, 6.2, 7.5, 8.8, 10.1, 11.4, 12.7]
+        ScratchPad.recorded.should.eql? [1.0, 2.3, 3.6, 4.9, 6.2, 7.5, 8.8, 10.1, 11.4, 12.7]
       end
     end
 
     describe "with a negative step" do
       it "yields while decreasing self by step while self > stop" do
         @step.call(5, 1.5, -1, &@prc)
-        ScratchPad.recorded.should eql [5.0, 4.0, 3.0, 2.0]
+        ScratchPad.recorded.should.eql? [5.0, 4.0, 3.0, 2.0]
       end
 
       it "yields once when self equals stop" do
         @step.call(1.5, 1.5, -1, &@prc)
-        ScratchPad.recorded.should eql [1.5]
+        ScratchPad.recorded.should.eql? [1.5]
       end
 
       it "does not yield when self is less than stop" do
@@ -119,24 +119,24 @@ describe :numeric_step, :shared => true do
       it "is careful about not yielding a value smaller than limit" do
         # As -9*1.3-1.0 == -12.700000000000001 < -12.7, we test:
         @step.call(-1.0, -12.7, -1.3, &@prc)
-        ScratchPad.recorded.should eql [-1.0, -2.3, -3.6, -4.9, -6.2, -7.5, -8.8, -10.1, -11.4, -12.7]
+        ScratchPad.recorded.should.eql? [-1.0, -2.3, -3.6, -4.9, -6.2, -7.5, -8.8, -10.1, -11.4, -12.7]
       end
     end
 
     describe "with a positive Infinity step" do
       it "yields once if self < stop" do
         @step.call(42, 100, infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once when stop is Infinity" do
         @step.call(42, infinity_value, infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once when self equals stop" do
         @step.call(42, 42, infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once when self and stop are Infinity" do
@@ -159,17 +159,17 @@ describe :numeric_step, :shared => true do
     describe "with a negative Infinity step" do
       it "yields once if self > stop" do
         @step.call(42, 6, -infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once if stop is -Infinity" do
         @step.call(42, -infinity_value, -infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once when self equals stop" do
         @step.call(42, 42, -infinity_value, &@prc)
-        ScratchPad.recorded.should eql [42.0]
+        ScratchPad.recorded.should.eql? [42.0]
       end
 
       it "yields once when self and stop are Infinity" do
@@ -224,77 +224,62 @@ describe :numeric_step, :shared => true do
   end
 
   describe "when step is a String" do
-    error = nil
-    ruby_version_is "2.4"..."2.5" do
-      error = TypeError
-    end
-    ruby_version_is "2.5" do
-      error = ArgumentError
-    end
-
-    describe "with self and stop as Fixnums" do
-      it "raises an #{error} when step is a numeric representation" do
-        -> { @step.call(1, 5, "1") {} }.should raise_error(error)
-        -> { @step.call(1, 5, "0.1") {} }.should raise_error(error)
-        -> { @step.call(1, 5, "1/3") {} }.should raise_error(error)
+    describe "with self and stop as Integers" do
+      it "raises an ArgumentError when step is a numeric representation" do
+        -> { @step.call(1, 5, "1") {} }.should.raise(ArgumentError)
+        -> { @step.call(1, 5, "0.1") {} }.should.raise(ArgumentError)
+        -> { @step.call(1, 5, "1/3") {} }.should.raise(ArgumentError)
       end
-      it "raises an #{error} with step as an alphanumeric string" do
-        -> { @step.call(1, 5, "foo") {} }.should raise_error(error)
+      it "raises an ArgumentError with step as an alphanumeric string" do
+        -> { @step.call(1, 5, "foo") {} }.should.raise(ArgumentError)
       end
     end
 
     describe "with self and stop as Floats" do
-      it "raises an #{error} when step is a numeric representation" do
-        -> { @step.call(1.1, 5.1, "1") {} }.should raise_error(error)
-        -> { @step.call(1.1, 5.1, "0.1") {} }.should raise_error(error)
-        -> { @step.call(1.1, 5.1, "1/3") {} }.should raise_error(error)
+      it "raises an ArgumentError when step is a numeric representation" do
+        -> { @step.call(1.1, 5.1, "1") {} }.should.raise(ArgumentError)
+        -> { @step.call(1.1, 5.1, "0.1") {} }.should.raise(ArgumentError)
+        -> { @step.call(1.1, 5.1, "1/3") {} }.should.raise(ArgumentError)
       end
-      it "raises an #{error} with step as an alphanumeric string" do
-        -> { @step.call(1.1, 5.1, "foo") {} }.should raise_error(error)
+      it "raises an ArgumentError with step as an alphanumeric string" do
+        -> { @step.call(1.1, 5.1, "foo") {} }.should.raise(ArgumentError)
       end
     end
   end
 
   it "does not rescue ArgumentError exceptions" do
-    -> { @step.call(1, 2) { raise ArgumentError, "" }}.should raise_error(ArgumentError)
+    -> { @step.call(1, 2) { raise ArgumentError, "" }}.should.raise(ArgumentError)
   end
 
   it "does not rescue TypeError exceptions" do
-    -> { @step.call(1, 2) { raise TypeError, "" } }.should raise_error(TypeError)
+    -> { @step.call(1, 2) { raise TypeError, "" } }.should.raise(TypeError)
   end
 
   describe "when no block is given" do
-    step_enum_class = Enumerator
-    ruby_version_is "2.6" do
-      step_enum_class = Enumerator::ArithmeticSequence
-    end
-
-    it "returns an #{step_enum_class} when step is 0" do
-      @step.call(1, 2, 0).should be_an_instance_of(step_enum_class)
-    end
+    step_enum_class = Enumerator::ArithmeticSequence
 
     it "returns an #{step_enum_class} when not passed a block and self > stop" do
-      @step.call(1, 0, 2).should be_an_instance_of(step_enum_class)
+      @step.call(1, 0, 2).should.instance_of?(step_enum_class)
     end
 
     it "returns an #{step_enum_class} when not passed a block and self < stop" do
-      @step.call(1, 2, 3).should be_an_instance_of(step_enum_class)
+      @step.call(1, 2, 3).should.instance_of?(step_enum_class)
     end
 
     it "returns an #{step_enum_class} that uses the given step" do
-      @step.call(0, 5, 2).to_a.should eql [0, 2, 4]
+      @step.call(0, 5, 2).to_a.should.eql? [0, 2, 4]
     end
 
     describe "when step is a String" do
-      describe "with self and stop as Fixnums" do
+      describe "with self and stop as Integers" do
         it "returns an Enumerator" do
-          @step.call(1, 5, "foo").should be_an_instance_of(Enumerator)
+          @step.call(1, 5, "foo").should.instance_of?(Enumerator)
         end
       end
 
       describe "with self and stop as Floats" do
         it "returns an Enumerator" do
-          @step.call(1.1, 5.1, "foo").should be_an_instance_of(Enumerator)
+          @step.call(1.1, 5.1, "foo").should.instance_of?(Enumerator)
         end
       end
     end
@@ -302,38 +287,30 @@ describe :numeric_step, :shared => true do
     describe "returned Enumerator" do
       describe "size" do
         describe "when step is a String" do
-          error = nil
-          ruby_version_is "2.4"..."2.5" do
-            error = TypeError
-          end
-          ruby_version_is "2.5" do
-            error = ArgumentError
-          end
-
-          describe "with self and stop as Fixnums" do
-            it "raises an #{error} when step is a numeric representation" do
-              -> { @step.call(1, 5, "1").size }.should raise_error(error)
-              -> { @step.call(1, 5, "0.1").size }.should raise_error(error)
-              -> { @step.call(1, 5, "1/3").size }.should raise_error(error)
+          describe "with self and stop as Integers" do
+            it "raises an ArgumentError when step is a numeric representation" do
+              -> { @step.call(1, 5, "1").size }.should.raise(ArgumentError)
+              -> { @step.call(1, 5, "0.1").size }.should.raise(ArgumentError)
+              -> { @step.call(1, 5, "1/3").size }.should.raise(ArgumentError)
             end
-            it "raises an #{error} with step as an alphanumeric string" do
-              -> { @step.call(1, 5, "foo").size }.should raise_error(error)
+            it "raises an ArgumentError with step as an alphanumeric string" do
+              -> { @step.call(1, 5, "foo").size }.should.raise(ArgumentError)
             end
           end
 
           describe "with self and stop as Floats" do
-            it "raises an #{error} when step is a numeric representation" do
-              -> { @step.call(1.1, 5.1, "1").size }.should raise_error(error)
-              -> { @step.call(1.1, 5.1, "0.1").size }.should raise_error(error)
-              -> { @step.call(1.1, 5.1, "1/3").size }.should raise_error(error)
+            it "raises an ArgumentError when step is a numeric representation" do
+              -> { @step.call(1.1, 5.1, "1").size }.should.raise(ArgumentError)
+              -> { @step.call(1.1, 5.1, "0.1").size }.should.raise(ArgumentError)
+              -> { @step.call(1.1, 5.1, "1/3").size }.should.raise(ArgumentError)
             end
-            it "raises an #{error} with step as an alphanumeric string" do
-              -> { @step.call(1.1, 5.1, "foo").size }.should raise_error(error)
+            it "raises an ArgumentError with step as an alphanumeric string" do
+              -> { @step.call(1.1, 5.1, "foo").size }.should.raise(ArgumentError)
             end
           end
         end
 
-        describe "when self, stop and step are Fixnums and step is positive" do
+        describe "when self, stop and step are Integers and step is positive" do
           it "returns the difference between self and stop divided by the number of steps" do
             @step.call(5, 10, 11).size.should == 1
             @step.call(5, 10, 6).size.should == 1
@@ -350,7 +327,7 @@ describe :numeric_step, :shared => true do
           end
         end
 
-        describe "when self, stop and step are Fixnums and step is negative" do
+        describe "when self, stop and step are Integers and step is negative" do
           it "returns the difference between self and stop divided by the number of steps" do
             @step.call(10, 5, -11).size.should == 1
             @step.call(10, 5, -6).size.should == 1
diff --git a/spec/ruby/core/numeric/singleton_method_added_spec.rb b/spec/ruby/core/numeric/singleton_method_added_spec.rb
index 2091398e5d..327bb5662a 100644
--- a/spec/ruby/core/numeric/singleton_method_added_spec.rb
+++ b/spec/ruby/core/numeric/singleton_method_added_spec.rb
@@ -21,21 +21,21 @@ describe "Numeric#singleton_method_added" do
     -> do
       a = NumericSpecs::Subclass.new
       def a.test; end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
 
     -> do
       a = 1
       def a.test; end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
 
     -> do
       a = 1.5
       def a.test; end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
 
     -> do
       a = bignum_value
       def a.test; end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/numeric/step_spec.rb b/spec/ruby/core/numeric/step_spec.rb
index e9067864c8..6896009eb6 100644
--- a/spec/ruby/core/numeric/step_spec.rb
+++ b/spec/ruby/core/numeric/step_spec.rb
@@ -6,11 +6,11 @@ describe "Numeric#step" do
 
   describe 'with positional args' do
     it "raises an ArgumentError when step is 0" do
-      -> { 1.step(5, 0) {} }.should raise_error(ArgumentError)
+      -> { 1.step(5, 0) {} }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when step is 0.0" do
-      -> { 1.step(2, 0.0) {} }.should raise_error(ArgumentError)
+      -> { 1.step(2, 0.0) {} }.should.raise(ArgumentError)
     end
 
     before :all do
@@ -21,45 +21,10 @@ describe "Numeric#step" do
     it_behaves_like :numeric_step, :step
 
     describe "when no block is given" do
-      step_enum_class = Enumerator
-      ruby_version_is "2.6" do
-        step_enum_class = Enumerator::ArithmeticSequence
-      end
-
-      it "returns an #{step_enum_class} when step is 0" do
-        1.step(5, 0).should be_an_instance_of(step_enum_class)
-      end
-
-      it "returns an #{step_enum_class} when step is 0.0" do
-        1.step(2, 0.0).should be_an_instance_of(step_enum_class)
-      end
+      step_enum_class = Enumerator::ArithmeticSequence
 
       describe "returned #{step_enum_class}" do
         describe "size" do
-          ruby_version_is ""..."2.6" do
-            it "raises an ArgumentError when step is 0" do
-              enum = 1.step(5, 0)
-              -> { enum.size }.should raise_error(ArgumentError)
-            end
-
-            it "raises an ArgumentError when step is 0.0" do
-              enum = 1.step(2, 0.0)
-              -> { enum.size }.should raise_error(ArgumentError)
-            end
-          end
-
-          ruby_version_is "2.6" do
-            it "is infinity when step is 0" do
-              enum = 1.step(5, 0)
-              enum.size.should == Float::INFINITY
-            end
-
-            it "is infinity when step is 0.0" do
-              enum = 1.step(2, 0.0)
-              enum.size.should == Float::INFINITY
-            end
-          end
-
           it "defaults to an infinite size" do
             enum = 1.step
             enum.size.should == Float::INFINITY
@@ -67,38 +32,15 @@ describe "Numeric#step" do
         end
 
         describe "type" do
-          ruby_version_is ""..."2.6" do
-            it "returns an instance of Enumerator" do
-              1.step(10).class.should == Enumerator
-            end
-          end
-
-          ruby_version_is "2.6" do
-            it "returns an instance of Enumerator::ArithmeticSequence" do
-              1.step(10).class.should == Enumerator::ArithmeticSequence
-            end
+          it "returns an instance of Enumerator::ArithmeticSequence" do
+            1.step(10).class.should == Enumerator::ArithmeticSequence
           end
         end
       end
     end
-
   end
 
   describe 'with keyword arguments' do
-    it "doesn't raise an error when step is 0" do
-      -> { 1.step(to: 5, by: 0) { break } }.should_not raise_error
-    end
-
-    it "doesn't raise an error when step is 0.0" do
-      -> { 1.step(to: 2, by: 0.0) { break } }.should_not raise_error
-    end
-
-    it "should loop over self when step is 0 or 0.0" do
-      1.step(to: 2, by: 0.0).take(5).should eql [1.0, 1.0, 1.0, 1.0, 1.0]
-      1.step(to: 2, by: 0).take(5).should eql [1, 1, 1, 1, 1]
-      1.1.step(to: 2, by: 0).take(5).should eql [1.1, 1.1, 1.1, 1.1, 1.1]
-    end
-
     describe "when no block is given" do
       describe "returned Enumerator" do
         describe "size" do
@@ -106,14 +48,6 @@ describe "Numeric#step" do
             1.step(by: 42).size.should == infinity_value
           end
 
-          it "should return infinity_value when step is 0" do
-            1.step(to: 5, by: 0).size.should == infinity_value
-          end
-
-          it "should return infinity_value when step is 0.0" do
-            1.step(to: 2, by: 0.0).size.should == infinity_value
-          end
-
           it "should return infinity_value when ascending towards a limit of Float::INFINITY" do
             1.step(to: Float::INFINITY, by: 42).size.should == infinity_value
           end
@@ -146,38 +80,25 @@ describe "Numeric#step" do
   end
 
   describe 'with mixed arguments' do
-    it "doesn't raise an error when step is 0" do
-      -> { 1.step(5, by: 0) { break } }.should_not raise_error
+    it " raises an ArgumentError when step is 0" do
+      -> { 1.step(5, by: 0) { break } }.should.raise(ArgumentError)
     end
 
-    it "doesn't raise an error when step is 0.0" do
-      -> { 1.step(2, by: 0.0) { break } }.should_not raise_error
+    it "raises an ArgumentError when step is 0.0" do
+      -> { 1.step(2, by: 0.0) { break } }.should.raise(ArgumentError)
     end
 
     it "raises a ArgumentError when limit and to are defined" do
-      -> { 1.step(5, 1, to: 5) { break } }.should raise_error(ArgumentError)
+      -> { 1.step(5, 1, to: 5) { break } }.should.raise(ArgumentError)
     end
 
     it "raises a ArgumentError when step and by are defined" do
-      -> { 1.step(5, 1, by: 5) { break } }.should raise_error(ArgumentError)
-    end
-
-    it "should loop over self when step is 0 or 0.0" do
-      1.step(2, by: 0.0).take(5).should eql [1.0, 1.0, 1.0, 1.0, 1.0]
-      1.step(2, by: 0).take(5).should eql [1, 1, 1, 1, 1]
-      1.1.step(2, by: 0).take(5).should eql [1.1, 1.1, 1.1, 1.1, 1.1]
+      -> { 1.step(5, 1, by: 5) { break } }.should.raise(ArgumentError)
     end
 
     describe "when no block is given" do
       describe "returned Enumerator" do
         describe "size" do
-          it "should return infinity_value when step is 0" do
-            1.step(5, by: 0).size.should == infinity_value
-          end
-
-          it "should return infinity_value when step is 0.0" do
-            1.step(2, by: 0.0).size.should == infinity_value
-          end
         end
       end
     end
diff --git a/spec/ruby/core/numeric/to_c_spec.rb b/spec/ruby/core/numeric/to_c_spec.rb
index 75245a612e..70b7a9dd0c 100644
--- a/spec/ruby/core/numeric/to_c_spec.rb
+++ b/spec/ruby/core/numeric/to_c_spec.rb
@@ -22,7 +22,7 @@ describe "Numeric#to_c" do
 
   it "returns a Complex object" do
     @numbers.each do |number|
-      number.to_c.should be_an_instance_of(Complex)
+      number.to_c.should.instance_of?(Complex)
     end
   end
 
@@ -30,7 +30,7 @@ describe "Numeric#to_c" do
     @numbers.each do |number|
       real = number.to_c.real
       if Float === number and number.nan?
-        real.nan?.should be_true
+        real.nan?.should == true
       else
         real.should == number
       end
diff --git a/spec/ruby/core/numeric/zero_spec.rb b/spec/ruby/core/numeric/zero_spec.rb
index 9de71d1dc9..0fb7619bcd 100644
--- a/spec/ruby/core/numeric/zero_spec.rb
+++ b/spec/ruby/core/numeric/zero_spec.rb
@@ -8,11 +8,11 @@ describe "Numeric#zero?" do
 
   it "returns true if self is 0" do
     @obj.should_receive(:==).with(0).and_return(true)
-    @obj.zero?.should == true
+    @obj.should.zero?
   end
 
   it "returns false if self is not 0" do
     @obj.should_receive(:==).with(0).and_return(false)
-    @obj.zero?.should == false
+    @obj.should_not.zero?
   end
 end
diff --git a/spec/ruby/core/objectspace/_id2ref_spec.rb b/spec/ruby/core/objectspace/_id2ref_spec.rb
index 1d8ad02deb..a9fd526b7d 100644
--- a/spec/ruby/core/objectspace/_id2ref_spec.rb
+++ b/spec/ruby/core/objectspace/_id2ref_spec.rb
@@ -1,25 +1,65 @@
 require_relative '../../spec_helper'
 
-describe "ObjectSpace._id2ref" do
-  it "converts an object id to a reference to the object" do
-    s = "I am a string"
-    r = ObjectSpace._id2ref(s.object_id)
-    r.should == s
+ruby_version_is "4.0" do
+  describe "ObjectSpace._id2ref" do
+    it "is deprecated" do
+      id = nil.object_id
+      -> {
+        ObjectSpace._id2ref(id)
+      }.should complain(/warning: ObjectSpace\._id2ref is deprecated/)
+    end
   end
+end
 
-  it "retrieves a Fixnum by object_id" do
-    f = 1
-    r = ObjectSpace._id2ref(f.object_id)
-    r.should == f
-  end
+ruby_version_is ""..."4.0" do
+  describe "ObjectSpace._id2ref" do
+    it "converts an object id to a reference to the object" do
+      s = "I am a string"
+      r = ObjectSpace._id2ref(s.object_id)
+      r.should == s
+    end
 
-  it "retrieves a Symbol by object_id" do
-    s = :sym
-    r = ObjectSpace._id2ref(s.object_id)
-    r.should == s
-  end
+    it "retrieves true by object_id" do
+      ObjectSpace._id2ref(true.object_id).should == true
+    end
+
+    it "retrieves false by object_id" do
+      ObjectSpace._id2ref(false.object_id).should == false
+    end
+
+    it "retrieves nil by object_id" do
+      ObjectSpace._id2ref(nil.object_id).should == nil
+    end
+
+    it "retrieves a small Integer by object_id" do
+      ObjectSpace._id2ref(1.object_id).should == 1
+      ObjectSpace._id2ref((-42).object_id).should == -42
+    end
+
+    it "retrieves a large Integer by object_id" do
+      obj = 1 << 88
+      ObjectSpace._id2ref(obj.object_id).should.equal?(obj)
+    end
+
+    it "retrieves a Symbol by object_id" do
+      ObjectSpace._id2ref(:sym.object_id).should.equal?(:sym)
+    end
+
+    it "retrieves a String by object_id" do
+      obj = "str"
+      ObjectSpace._id2ref(obj.object_id).should.equal?(obj)
+    end
+
+    it "retrieves a frozen literal String by object_id" do
+      ObjectSpace._id2ref("frozen string literal _id2ref".freeze.object_id).should.equal?("frozen string literal _id2ref".freeze)
+    end
+
+    it "retrieves an Encoding by object_id" do
+      ObjectSpace._id2ref(Encoding::UTF_8.object_id).should.equal?(Encoding::UTF_8)
+    end
 
-  it 'raises RangeError when an object could not be found' do
-    proc { ObjectSpace._id2ref(1 << 60) }.should raise_error(RangeError)
+    it 'raises RangeError when an object could not be found' do
+      proc { ObjectSpace._id2ref(1 << 60) }.should.raise(RangeError)
+    end
   end
 end
diff --git a/spec/ruby/core/objectspace/add_finalizer_spec.rb b/spec/ruby/core/objectspace/add_finalizer_spec.rb
deleted file mode 100644
index 3540ac0413..0000000000
--- a/spec/ruby/core/objectspace/add_finalizer_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ObjectSpace.add_finalizer" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/objectspace/call_finalizer_spec.rb b/spec/ruby/core/objectspace/call_finalizer_spec.rb
deleted file mode 100644
index 6dce92ddd6..0000000000
--- a/spec/ruby/core/objectspace/call_finalizer_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ObjectSpace.call_finalizer" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/objectspace/define_finalizer_spec.rb b/spec/ruby/core/objectspace/define_finalizer_spec.rb
index 3f7b1ae576..5441cb4a21 100644
--- a/spec/ruby/core/objectspace/define_finalizer_spec.rb
+++ b/spec/ruby/core/objectspace/define_finalizer_spec.rb
@@ -1,60 +1,162 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-# NOTE: A call to define_finalizer does not guarantee that the
-# passed proc or callable will be called at any particular time.
+# Why do we not test that finalizers are run by the GC? The documentation
+# says that finalizers are never guaranteed to be run, so we can't
+# spec that they are. On some implementations of Ruby the finalizers may
+# run asynchronously, meaning that we can't predict when they'll run,
+# even if they were guaranteed to do so. Even on MRI finalizers can be
+# very unpredictable, due to conservative stack scanning and references
+# left in unused memory.
+
 describe "ObjectSpace.define_finalizer" do
   it "raises an ArgumentError if the action does not respond to call" do
     -> {
-      ObjectSpace.define_finalizer("", mock("ObjectSpace.define_finalizer no #call"))
-    }.should raise_error(ArgumentError)
+      ObjectSpace.define_finalizer(Object.new, mock("ObjectSpace.define_finalizer no #call"))
+    }.should.raise(ArgumentError)
   end
 
   it "accepts an object and a proc" do
-    handler = -> obj { obj }
-    ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
+    handler = -> id { id }
+    ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
+  end
+
+  it "accepts an object and a bound method" do
+    handler = mock("callable")
+    def handler.finalize(id) end
+    finalize = handler.method(:finalize)
+    ObjectSpace.define_finalizer(Object.new, finalize).should == [0, finalize]
   end
 
   it "accepts an object and a callable" do
     handler = mock("callable")
-    def handler.call(obj) end
-    ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
+    def handler.call(id) end
+    ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
+  end
+
+  it "accepts an object and a block" do
+    handler = -> id { id }
+    ObjectSpace.define_finalizer(Object.new, &handler).should == [0, handler]
   end
 
   it "raises ArgumentError trying to define a finalizer on a non-reference" do
     -> {
       ObjectSpace.define_finalizer(:blah) { 1 }
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   # see [ruby-core:24095]
   it "calls finalizer on process termination" do
     code = <<-RUBY
       def scoped
-        Proc.new { puts "finalized" }
+        Proc.new { puts "finalizer run" }
       end
       handler = scoped
-      obj = "Test"
+      obj = +"Test"
       ObjectSpace.define_finalizer(obj, handler)
       exit 0
     RUBY
 
-    ruby_exe(code).should == "finalized\n"
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer run\n")
   end
 
-  it "calls finalizer at exit even if it is self-referencing" do
+  it "warns if the finalizer has the object as the receiver" do
     code = <<-RUBY
-      obj = "Test"
-      handler = Proc.new { puts "finalized" }
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, proc {
+            puts "finalizer run"
+          })
+        end
+      end
+      CapturesSelf.new
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
+
+  it "warns if the finalizer is a method bound to the receiver" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, method(:finalize))
+        end
+        def finalize(id)
+          puts "finalizer run"
+        end
+      end
+      CapturesSelf.new
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
+
+  it "warns if the finalizer was a block in the receiver" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self) do
+            puts "finalizer run"
+          end
+        end
+      end
+      CapturesSelf.new
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("warning: finalizer references object to be finalized\n")
+  end
+
+  it "calls a finalizer at exit even if it is self-referencing" do
+    code = <<-RUBY
+      obj = +"Test"
+      handler = Proc.new { puts "finalizer run" }
       ObjectSpace.define_finalizer(obj, handler)
       exit 0
     RUBY
 
-    ruby_exe(code).should == "finalized\n"
+    ruby_exe(code).should.include?("finalizer run\n")
   end
 
-  it "allows multiple finalizers with different 'callables' to be defined" do
+  it "calls a finalizer at exit even if it is indirectly self-referencing" do
+    code = <<-RUBY
+      class CapturesSelf
+        def initialize
+          ObjectSpace.define_finalizer(self, finalizer(self))
+        end
+        def finalizer(zelf)
+          proc do
+            puts "finalizer run"
+          end
+        end
+      end
+      CapturesSelf.new
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer run\n")
+  end
+
+  it "calls a finalizer defined in a finalizer running at exit" do
     code = <<-RUBY
+      obj = +"Test"
+      handler = Proc.new do
+        obj2 = +"Test"
+        handler2 = Proc.new { puts "finalizer 2 run" }
+        ObjectSpace.define_finalizer(obj2, handler2)
+        exit 0
+      end
+      ObjectSpace.define_finalizer(obj, handler)
+      exit 0
+    RUBY
+
+    ruby_exe(code, :args => "2>&1").should.include?("finalizer 2 run\n")
+  end
+
+  it "allows multiple finalizers with different 'callables' to be defined" do
+    code = <<-'RUBY'
       obj = Object.new
 
       ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized1\n" })
@@ -65,4 +167,51 @@ describe "ObjectSpace.define_finalizer" do
 
     ruby_exe(code).lines.sort.should == ["finalized1\n", "finalized2\n"]
   end
+
+  it "defines same finalizer only once" do
+    code = <<~RUBY
+      obj = Object.new
+      p = proc { |id| print "ok" }
+      ObjectSpace.define_finalizer(obj, p.dup)
+      ObjectSpace.define_finalizer(obj, p.dup)
+    RUBY
+
+    ruby_exe(code).should == "ok"
+  end
+
+  it "returns the defined finalizer" do
+    obj = Object.new
+    p = proc { |id| }
+    p2 = p.dup
+
+    ret = ObjectSpace.define_finalizer(obj, p)
+    ret.should == [0, p]
+    ret[1].should.equal?(p)
+
+    ret = ObjectSpace.define_finalizer(obj, p2)
+    ret.should == [0, p]
+    ret[1].should.equal?(p)
+  end
+
+  describe "when $VERBOSE is not nil" do
+    it "warns if an exception is raised in finalizer" do
+      code = <<-RUBY
+        ObjectSpace.define_finalizer(Object.new) { raise "finalizing" }
+      RUBY
+
+      out = ruby_exe(code, args: "2>&1")
+      out.should.include?("warning: Exception in finalizer")
+      out.should.include?("finalizing")
+    end
+  end
+
+  describe "when $VERBOSE is nil" do
+    it "does not warn even if an exception is raised in finalizer" do
+      code = <<-RUBY
+        ObjectSpace.define_finalizer(Object.new) { raise "finalizing" }
+      RUBY
+
+      ruby_exe(code, args: "2>&1", options: "-W0").should == ""
+    end
+  end
 end
diff --git a/spec/ruby/core/objectspace/each_object_spec.rb b/spec/ruby/core/objectspace/each_object_spec.rb
index 09a582afaf..aee0fd629c 100644
--- a/spec/ruby/core/objectspace/each_object_spec.rb
+++ b/spec/ruby/core/objectspace/each_object_spec.rb
@@ -39,7 +39,7 @@ describe "ObjectSpace.each_object" do
     new_obj = klass.new
 
     counter = ObjectSpace.each_object(klass)
-    counter.should be_an_instance_of(Enumerator)
+    counter.should.instance_of?(Enumerator)
     counter.each{}.should == 1
     # this is needed to prevent the new_obj from being GC'd too early
     new_obj.should_not == nil
@@ -47,20 +47,20 @@ describe "ObjectSpace.each_object" do
 
   it "finds an object stored in a global variable" do
     $object_space_global_variable = ObjectSpaceFixtures::ObjectToBeFound.new(:global)
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:global)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:global)
   end
 
   it "finds an object stored in a top-level constant" do
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:top_level_constant)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:top_level_constant)
   end
 
   it "finds an object stored in a second-level constant" do
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:second_level_constant)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:second_level_constant)
   end
 
   it "finds an object stored in a local variable" do
     local = ObjectSpaceFixtures::ObjectToBeFound.new(:local)
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local)
   end
 
   it "finds an object stored in a local variable captured in a block explicitly" do
@@ -69,7 +69,7 @@ describe "ObjectSpace.each_object" do
       Proc.new { local_in_block }
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local_in_block_explicit)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local_in_block_explicit)
   end
 
   it "finds an object stored in a local variable captured in a block implicitly" do
@@ -78,11 +78,11 @@ describe "ObjectSpace.each_object" do
       Proc.new { }
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local_in_block_implicit)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local_in_block_implicit)
   end
 
   it "finds an object stored in a local variable captured in by a method defined with a block" do
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:captured_by_define_method)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:captured_by_define_method)
   end
 
   it "finds an object stored in a local variable captured in a Proc#binding" do
@@ -91,7 +91,7 @@ describe "ObjectSpace.each_object" do
       Proc.new { }.binding
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local_in_proc_binding)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local_in_proc_binding)
   end
 
   it "finds an object stored in a local variable captured in a Kernel#binding" do
@@ -100,45 +100,45 @@ describe "ObjectSpace.each_object" do
       binding
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local_in_kernel_binding)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local_in_kernel_binding)
   end
 
   it "finds an object stored in a local variable set in a binding manually" do
     b = binding
     b.eval("local = ObjectSpaceFixtures::ObjectToBeFound.new(:local_in_manual_binding)")
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:local_in_manual_binding)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:local_in_manual_binding)
   end
 
   it "finds an object stored in an array" do
     array = [ObjectSpaceFixtures::ObjectToBeFound.new(:array)]
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:array)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:array)
   end
 
   it "finds an object stored in a hash key" do
     hash = {ObjectSpaceFixtures::ObjectToBeFound.new(:hash_key) => :value}
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:hash_key)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:hash_key)
   end
 
   it "finds an object stored in a hash value" do
     hash = {a: ObjectSpaceFixtures::ObjectToBeFound.new(:hash_value)}
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:hash_value)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:hash_value)
   end
 
   it "finds an object stored in an instance variable" do
     local = ObjectSpaceFixtures::ObjectWithInstanceVariable.new
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:instance_variable)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:instance_variable)
   end
 
   it "finds an object stored in a thread local" do
     thread = Thread.new {}
     thread.thread_variable_set(:object_space_thread_local, ObjectSpaceFixtures::ObjectToBeFound.new(:thread_local))
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:thread_local)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:thread_local)
     thread.join
   end
 
   it "finds an object stored in a fiber local" do
     Thread.current[:object_space_fiber_local] = ObjectSpaceFixtures::ObjectToBeFound.new(:fiber_local)
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:fiber_local)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:fiber_local)
   end
 
   it "finds an object captured in an at_exit handler" do
@@ -150,7 +150,7 @@ describe "ObjectSpace.each_object" do
       end
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:at_exit)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:at_exit)
   end
 
   it "finds an object captured in finalizer" do
@@ -164,9 +164,9 @@ describe "ObjectSpace.each_object" do
       })
     }.call
 
-    ObjectSpaceFixtures.to_be_found_symbols.should include(:finalizer)
+    ObjectSpaceFixtures.to_be_found_symbols.should.include?(:finalizer)
 
-    alive.should_not be_nil
+    alive.should_not == nil
   end
 
   describe "on singleton classes" do
@@ -185,8 +185,8 @@ describe "ObjectSpace.each_object" do
     end
 
     it "walks singleton classes" do
-      @sclass.should be_kind_of(@meta)
-      ObjectSpace.each_object(@meta).to_a.should include(@sclass)
+      @sclass.should.is_a?(@meta)
+      ObjectSpace.each_object(@meta).to_a.should.include?(@sclass)
     end
   end
 
@@ -202,7 +202,7 @@ describe "ObjectSpace.each_object" do
     expected = [ a, b, c, d ]
 
     expected << c_sclass
-    c_sclass.should be_kind_of(a.singleton_class)
+    c_sclass.should.is_a?(a.singleton_class)
 
     b.extend Enumerable # included modules should not be walked
 
diff --git a/spec/ruby/core/objectspace/finalizers_spec.rb b/spec/ruby/core/objectspace/finalizers_spec.rb
deleted file mode 100644
index e7f20fc8a0..0000000000
--- a/spec/ruby/core/objectspace/finalizers_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ObjectSpace.finalizers" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/objectspace/garbage_collect_spec.rb b/spec/ruby/core/objectspace/garbage_collect_spec.rb
index 1aec3ea072..d2db22e0aa 100644
--- a/spec/ruby/core/objectspace/garbage_collect_spec.rb
+++ b/spec/ruby/core/objectspace/garbage_collect_spec.rb
@@ -3,15 +3,15 @@ require_relative '../../spec_helper'
 describe "ObjectSpace.garbage_collect" do
 
   it "can be invoked without any exceptions" do
-    -> { ObjectSpace.garbage_collect }.should_not raise_error
+    -> { ObjectSpace.garbage_collect }.should_not.raise
   end
 
-  it "doesn't accept any arguments" do
-    -> { ObjectSpace.garbage_collect(1) }.should raise_error(ArgumentError)
+  it "accepts keyword arguments" do
+    ObjectSpace.garbage_collect(full_mark: true, immediate_sweep: true).should == nil
   end
 
   it "ignores the supplied block" do
-    -> { ObjectSpace.garbage_collect {} }.should_not raise_error
+    -> { ObjectSpace.garbage_collect {} }.should_not.raise
   end
 
   it "always returns nil" do
diff --git a/spec/ruby/core/objectspace/remove_finalizer_spec.rb b/spec/ruby/core/objectspace/remove_finalizer_spec.rb
deleted file mode 100644
index 0b2b8cf16b..0000000000
--- a/spec/ruby/core/objectspace/remove_finalizer_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "ObjectSpace.remove_finalizer" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/objectspace/undefine_finalizer_spec.rb b/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
index 11d43121f8..98ffc6a986 100644
--- a/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
+++ b/spec/ruby/core/objectspace/undefine_finalizer_spec.rb
@@ -1,5 +1,33 @@
 require_relative '../../spec_helper'
 
 describe "ObjectSpace.undefine_finalizer" do
-  it "needs to be reviewed for spec completeness"
+  it "removes finalizers for an object" do
+    code = <<~RUBY
+      obj = Object.new
+      ObjectSpace.define_finalizer(obj, proc { |id| puts "hello" })
+      ObjectSpace.undefine_finalizer(obj)
+    RUBY
+
+    ruby_exe(code).should.empty?
+  end
+
+  it "should not remove finalizers for a frozen object" do
+    code = <<~RUBY
+      obj = Object.new
+      ObjectSpace.define_finalizer(obj, proc { |id| print "ok" })
+      obj.freeze
+      begin
+        ObjectSpace.undefine_finalizer(obj)
+      rescue
+      end
+    RUBY
+
+    ruby_exe(code).should == "ok"
+  end
+
+  it "should raise when removing finalizers for a frozen object" do
+    obj = Object.new
+    obj.freeze
+    -> { ObjectSpace.undefine_finalizer(obj) }.should.raise(FrozenError)
+  end
 end
diff --git a/spec/ruby/core/objectspace/weakkeymap/clear_spec.rb b/spec/ruby/core/objectspace/weakkeymap/clear_spec.rb
new file mode 100644
index 0000000000..b1804ec9b0
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/clear_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#clear" do
+  it "removes all the entries" do
+    m = ObjectSpace::WeakKeyMap.new
+
+    key = Object.new
+    value = Object.new
+    m[key] = value
+
+    key2 = Object.new
+    value2 = Object.new
+    m[key2] = value2
+
+    m.clear
+
+    m.key?(key).should == false
+    m.key?(key2).should == false
+  end
+
+  it "returns self" do
+    m = ObjectSpace::WeakKeyMap.new
+    m.clear.should.equal?(m)
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/delete_spec.rb b/spec/ruby/core/objectspace/weakkeymap/delete_spec.rb
new file mode 100644
index 0000000000..ad32c2c75e
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/delete_spec.rb
@@ -0,0 +1,49 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#delete" do
+  it "removes the entry and returns the deleted value" do
+    m = ObjectSpace::WeakKeyMap.new
+    key = Object.new
+    value = Object.new
+    m[key] = value
+
+    m.delete(key).should == value
+    m.key?(key).should == false
+  end
+
+  it "uses equality semantic" do
+    m = ObjectSpace::WeakKeyMap.new
+    key = "foo".upcase
+    value = Object.new
+    m[key] = value
+
+    m.delete("foo".upcase).should == value
+    m.key?(key).should == false
+  end
+
+  it "calls supplied block if the key is not found" do
+    key = Object.new
+    m = ObjectSpace::WeakKeyMap.new
+    return_value = m.delete(key) do |yielded_key|
+      yielded_key.should == key
+      5
+    end
+    return_value.should == 5
+  end
+
+  it "returns nil if the key is not found when no block is given" do
+    m = ObjectSpace::WeakKeyMap.new
+    m.delete(Object.new).should == nil
+  end
+
+  it "returns nil when a key cannot be garbage collected" do
+    map = ObjectSpace::WeakKeyMap.new
+
+    map.delete(1).should == nil
+    map.delete(1.0).should == nil
+    map.delete(:a).should == nil
+    map.delete(true).should == nil
+    map.delete(false).should == nil
+    map.delete(nil).should == nil
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/element_reference_spec.rb b/spec/ruby/core/objectspace/weakkeymap/element_reference_spec.rb
new file mode 100644
index 0000000000..53eff79c40
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/element_reference_spec.rb
@@ -0,0 +1,105 @@
+require_relative '../../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "ObjectSpace::WeakKeyMap#[]" do
+  it "is faithful to the map's content" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    map[key1] = ref1
+    map[key1].should == ref1
+    map[key1] = ref1
+    map[key1].should == ref1
+    map[key2] = ref2
+    map[key1].should == ref1
+    map[key2].should == ref2
+  end
+
+  it "compares keys with #eql? semantics" do
+    map = ObjectSpace::WeakKeyMap.new
+    key = [1.0]
+    map[key] = "x"
+    map[[1]].should == nil
+    map[[1.0]].should == "x"
+    key.should == [1.0] # keep the key alive until here to keep the map entry
+
+    map = ObjectSpace::WeakKeyMap.new
+    key = [1]
+    map[key] = "x"
+    map[[1.0]].should == nil
+    map[[1]].should == "x"
+    key.should == [1] # keep the key alive until here to keep the map entry
+
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a a].map(&:upcase)
+    ref = "x"
+    map[key1] = ref
+    map[key2].should == ref
+  end
+
+  it "compares key via #hash first" do
+    x = mock('0')
+    x.should_receive(:hash).and_return(0)
+
+    map = ObjectSpace::WeakKeyMap.new
+    key = 'foo'
+    map[key] = :bar
+    map[x].should == nil
+  end
+
+  it "does not compare keys with different #hash values via #eql?" do
+    x = mock('x')
+    x.should_not_receive(:eql?)
+    x.stub!(:hash).and_return(0)
+
+    y = mock('y')
+    y.should_not_receive(:eql?)
+    y.stub!(:hash).and_return(1)
+
+    map = ObjectSpace::WeakKeyMap.new
+    map[y] = 1
+    map[x].should == nil
+  end
+
+  it "compares keys with the same #hash value via #eql?" do
+    x = mock('x')
+    x.should_receive(:eql?).and_return(true)
+    x.stub!(:hash).and_return(42)
+
+    y = mock('y')
+    y.should_not_receive(:eql?)
+    y.stub!(:hash).and_return(42)
+
+    map = ObjectSpace::WeakKeyMap.new
+    map[y] = 1
+    map[x].should == 1
+  end
+
+  it "finds a value via an identical key even when its #eql? isn't reflexive" do
+    x = mock('x')
+    x.should_receive(:hash).at_least(1).and_return(42)
+    x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
+
+    map = ObjectSpace::WeakKeyMap.new
+    map[x] = :x
+    map[x].should == :x
+  end
+
+  it "supports keys with private #hash method" do
+    key = WeakKeyMapSpecs::KeyWithPrivateHash.new
+    map = ObjectSpace::WeakKeyMap.new
+    map[key] = 42
+    map[key].should == 42
+  end
+
+  it "returns nil and does not raise error when a key cannot be garbage collected" do
+    map = ObjectSpace::WeakKeyMap.new
+
+    map[1].should == nil
+    map[1.0].should == nil
+    map[:a].should == nil
+    map[true].should == nil
+    map[false].should == nil
+    map[nil].should == nil
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/element_set_spec.rb b/spec/ruby/core/objectspace/weakkeymap/element_set_spec.rb
new file mode 100644
index 0000000000..cf59aebc6f
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/element_set_spec.rb
@@ -0,0 +1,80 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#[]=" do
+  def should_accept(map, key, value)
+    (map[key] = value).should == value
+    map.should.key?(key)
+    map[key].should == value
+  end
+
+  it "is correct" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    should_accept(map, key1, ref1)
+    should_accept(map, key1, ref1)
+    should_accept(map, key2, ref2)
+    map[key1].should == ref1
+  end
+
+  it "requires the keys to implement #hash" do
+    map = ObjectSpace::WeakKeyMap.new
+    -> { map[BasicObject.new] = 1 }.should.raise(NoMethodError, /undefined method [`']hash' for an instance of BasicObject/)
+  end
+
+  it "accepts frozen keys or values" do
+    map = ObjectSpace::WeakKeyMap.new
+    x = Object.new
+    should_accept(map, x, true)
+    should_accept(map, x, false)
+    should_accept(map, x, 42)
+    should_accept(map, x, :foo)
+
+    y = Object.new.freeze
+    should_accept(map, x, y)
+    should_accept(map, y, x)
+  end
+
+  it "does not duplicate and freeze String keys (like Hash#[]= does)" do
+    map = ObjectSpace::WeakKeyMap.new
+    key = +"a"
+    map[key] = 1
+
+    map.getkey("a").should.equal? key
+    map.getkey("a").should_not.frozen?
+
+    key.should == "a" # keep the key alive until here to keep the map entry
+  end
+
+  context "a key cannot be garbage collected" do
+    it "raises ArgumentError when Integer is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[1] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+
+    it "raises ArgumentError when Float is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[1.0] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+
+    it "raises ArgumentError when Symbol is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[:a] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+
+    it "raises ArgumentError when true is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[true] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+
+    it "raises ArgumentError when false is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[false] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+
+    it "raises ArgumentError when nil is used as a key" do
+      map = ObjectSpace::WeakKeyMap.new
+      -> { map[nil] = "x" }.should.raise(ArgumentError, /WeakKeyMap (keys )?must be garbage collectable/)
+    end
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/fixtures/classes.rb b/spec/ruby/core/objectspace/weakkeymap/fixtures/classes.rb
new file mode 100644
index 0000000000..0fd04551b5
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/fixtures/classes.rb
@@ -0,0 +1,5 @@
+module WeakKeyMapSpecs
+  class KeyWithPrivateHash
+    private :hash
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/getkey_spec.rb b/spec/ruby/core/objectspace/weakkeymap/getkey_spec.rb
new file mode 100644
index 0000000000..798a2e2cda
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/getkey_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#getkey" do
+  it "returns the existing equal key" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a a].map(&:upcase)
+
+    map[key1] = true
+    map.getkey(key2).should.equal?(key1)
+    map.getkey("X").should == nil
+
+    key1.should == "A" # keep the key alive until here to keep the map entry
+    key2.should == "A" # keep the key alive until here to keep the map entry
+  end
+
+  it "returns nil when a key cannot be garbage collected" do
+    map = ObjectSpace::WeakKeyMap.new
+
+    map.getkey(1).should == nil
+    map.getkey(1.0).should == nil
+    map.getkey(:a).should == nil
+    map.getkey(true).should == nil
+    map.getkey(false).should == nil
+    map.getkey(nil).should == nil
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/inspect_spec.rb b/spec/ruby/core/objectspace/weakkeymap/inspect_spec.rb
new file mode 100644
index 0000000000..b6bb469158
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/inspect_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#inspect" do
+  it "only displays size in output" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2, key3 = "foo", "bar", "bar"
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakKeyMap:0x\h+ size=0>\z/
+    map[key1] = 1
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakKeyMap:0x\h+ size=1>\z/
+    map[key2] = 2
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakKeyMap:0x\h+ size=2>\z/
+    map[key3] = 3
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakKeyMap:0x\h+ size=2>\z/
+
+    key1.should == "foo" # keep the key alive until here to keep the map entry
+    key2.should == "bar" # keep the key alive until here to keep the map entry
+    key3.should == "bar" # keep the key alive until here to keep the map entry
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakkeymap/key_spec.rb b/spec/ruby/core/objectspace/weakkeymap/key_spec.rb
new file mode 100644
index 0000000000..e0b6866671
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakkeymap/key_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakKeyMap#key?" do
+  it "recognizes keys in use" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+
+    map[key1] = ref1
+    map.key?(key1).should == true
+    map[key1] = ref1
+    map.key?(key1).should == true
+    map[key2] = ref2
+    map.key?(key2).should == true
+  end
+
+  it "matches using equality semantics" do
+    map = ObjectSpace::WeakKeyMap.new
+    key1, key2 = %w[a a].map(&:upcase)
+    ref = "x"
+    map[key1] = ref
+    map.key?(key2).should == true
+  end
+
+  it "reports true if the pair exists and the value is nil" do
+    map = ObjectSpace::WeakKeyMap.new
+    key = Object.new
+    map[key] = nil
+    map.key?(key).should == true
+  end
+
+  it "returns false when a key cannot be garbage collected" do
+    map = ObjectSpace::WeakKeyMap.new
+
+    map.key?(1).should == false
+    map.key?(1.0).should == false
+    map.key?(:a).should == false
+    map.key?(true).should == false
+    map.key?(false).should == false
+    map.key?(nil).should == false
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/delete_spec.rb b/spec/ruby/core/objectspace/weakmap/delete_spec.rb
new file mode 100644
index 0000000000..03beebbb83
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/delete_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakMap#delete" do
+  it "removes the entry and returns the deleted value" do
+    m = ObjectSpace::WeakMap.new
+    key = Object.new
+    value = Object.new
+    m[key] = value
+
+    m.delete(key).should == value
+    m.key?(key).should == false
+  end
+
+  it "calls supplied block if the key is not found" do
+    key = Object.new
+    m = ObjectSpace::WeakMap.new
+    return_value = m.delete(key) do |yielded_key|
+      yielded_key.should == key
+      5
+    end
+    return_value.should == 5
+  end
+
+  it "returns nil if the key is not found when no block is given" do
+    m = ObjectSpace::WeakMap.new
+    m.delete(Object.new).should == nil
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/each_key_spec.rb b/spec/ruby/core/objectspace/weakmap/each_key_spec.rb
new file mode 100644
index 0000000000..df971deeb9
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/each_key_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+require_relative 'shared/each'
+
+describe "ObjectSpace::WeakMap#each_key" do
+  it_behaves_like :weakmap_members, -> map { a = []; map.each_key{ |k| a << k }; a }, %w[A B]
+end
+
+describe "ObjectSpace::WeakMap#each_key" do
+  it_behaves_like :weakmap_each, :each_key
+end
diff --git a/spec/ruby/core/objectspace/weakmap/each_pair_spec.rb b/spec/ruby/core/objectspace/weakmap/each_pair_spec.rb
new file mode 100644
index 0000000000..ea29edbd2f
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/each_pair_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+require_relative 'shared/each'
+
+describe "ObjectSpace::WeakMap#each_pair" do
+  it_behaves_like :weakmap_members, -> map { a = []; map.each_pair{ |k,v| a << "#{k}#{v}" }; a }, %w[Ax By]
+end
+
+describe "ObjectSpace::WeakMap#each_key" do
+  it_behaves_like :weakmap_each, :each_pair
+end
diff --git a/spec/ruby/core/objectspace/weakmap/each_spec.rb b/spec/ruby/core/objectspace/weakmap/each_spec.rb
new file mode 100644
index 0000000000..46fcb66a6f
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/each_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+require_relative 'shared/each'
+
+describe "ObjectSpace::WeakMap#each" do
+  it_behaves_like :weakmap_members, -> map { a = []; map.each{ |k,v| a << "#{k}#{v}" }; a }, %w[Ax By]
+end
+
+describe "ObjectSpace::WeakMap#each_key" do
+  it_behaves_like :weakmap_each, :each
+end
diff --git a/spec/ruby/core/objectspace/weakmap/each_value_spec.rb b/spec/ruby/core/objectspace/weakmap/each_value_spec.rb
new file mode 100644
index 0000000000..65a1a7f6fe
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/each_value_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+require_relative 'shared/each'
+
+describe "ObjectSpace::WeakMap#each_value" do
+  it_behaves_like :weakmap_members, -> map { a = []; map.each_value{ |k| a << k }; a }, %w[x y]
+end
+
+describe "ObjectSpace::WeakMap#each_key" do
+  it_behaves_like :weakmap_each, :each_value
+end
diff --git a/spec/ruby/core/objectspace/weakmap/element_reference_spec.rb b/spec/ruby/core/objectspace/weakmap/element_reference_spec.rb
new file mode 100644
index 0000000000..cb3174cbfa
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/element_reference_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakMap#[]" do
+  it "is faithful to the map's content" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    map[key1] = ref1
+    map[key1].should == ref1
+    map[key1] = ref1
+    map[key1].should == ref1
+    map[key2] = ref2
+    map[key1].should == ref1
+    map[key2].should == ref2
+  end
+
+  it "matches using identity semantics" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a a].map(&:upcase)
+    ref = "x"
+    map[key1] = ref
+    map[key2].should == nil
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/element_set_spec.rb b/spec/ruby/core/objectspace/weakmap/element_set_spec.rb
new file mode 100644
index 0000000000..8588877158
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/element_set_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakMap#[]=" do
+  def should_accept(map, key, value)
+    (map[key] = value).should == value
+    map.should.key?(key)
+    map[key].should == value
+  end
+
+  it "is correct" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    should_accept(map, key1, ref1)
+    should_accept(map, key1, ref1)
+    should_accept(map, key2, ref2)
+    map[key1].should == ref1
+  end
+
+  it "accepts primitive or frozen keys or values" do
+    map = ObjectSpace::WeakMap.new
+    x = Object.new
+    should_accept(map, true, x)
+    should_accept(map, false, x)
+    should_accept(map, nil, x)
+    should_accept(map, 42, x)
+    should_accept(map, :foo, x)
+
+    should_accept(map, x, true)
+    should_accept(map, x, false)
+    should_accept(map, x, 42)
+    should_accept(map, x, :foo)
+
+    y = Object.new.freeze
+    should_accept(map, x, y)
+    should_accept(map, y, x)
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/include_spec.rb b/spec/ruby/core/objectspace/weakmap/include_spec.rb
new file mode 100644
index 0000000000..54ca6b3030
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/include_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/include'
+
+describe "ObjectSpace::WeakMap#include?" do
+  it_behaves_like :weakmap_include?, :include?
+end
diff --git a/spec/ruby/core/objectspace/weakmap/inspect_spec.rb b/spec/ruby/core/objectspace/weakmap/inspect_spec.rb
new file mode 100644
index 0000000000..f064f6e3ea
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/inspect_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+
+describe "ObjectSpace::WeakMap#inspect" do
+  it "displays object pointers in output" do
+    map = ObjectSpace::WeakMap.new
+    # important to test with BasicObject (without Kernel) here to test edge cases
+    key1, key2 = [BasicObject.new, Object.new]
+    ref1, ref2 = [BasicObject.new, Object.new]
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakMap:0x\h+>\z/
+    map[key1] = ref1
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakMap:0x\h+: \#<BasicObject:0x\h+> => \#<BasicObject:0x\h+>>\z/
+    map[key1] = ref1
+    map.inspect.should =~ /\A\#<ObjectSpace::WeakMap:0x\h+: \#<BasicObject:0x\h+> => \#<BasicObject:0x\h+>>\z/
+    map[key2] = ref2
+
+    regexp1 = /\A\#<ObjectSpace::WeakMap:0x\h+: \#<BasicObject:0x\h+> => \#<BasicObject:0x\h+>, \#<Object:0x\h+> => \#<Object:0x\h+>>\z/
+    regexp2 = /\A\#<ObjectSpace::WeakMap:0x\h+: \#<Object:0x\h+> => \#<Object:0x\h+>, \#<BasicObject:0x\h+> => \#<BasicObject:0x\h+>>\z/
+    str = map.inspect
+    if str =~ regexp1
+      str.should =~ regexp1
+    else
+      str.should =~ regexp2
+    end
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/key_spec.rb b/spec/ruby/core/objectspace/weakmap/key_spec.rb
new file mode 100644
index 0000000000..999685ff95
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/key_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/include'
+
+describe "ObjectSpace::WeakMap#key?" do
+  it_behaves_like :weakmap_include?, :key?
+end
diff --git a/spec/ruby/core/objectspace/weakmap/keys_spec.rb b/spec/ruby/core/objectspace/weakmap/keys_spec.rb
new file mode 100644
index 0000000000..7b1494bdd7
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/keys_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+
+describe "ObjectSpace::WeakMap#keys" do
+  it_behaves_like :weakmap_members, -> map { map.keys }, %w[A B]
+end
diff --git a/spec/ruby/core/objectspace/weakmap/length_spec.rb b/spec/ruby/core/objectspace/weakmap/length_spec.rb
new file mode 100644
index 0000000000..3a935648b1
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/length_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/size'
+
+describe "ObjectSpace::WeakMap#length" do
+  it_behaves_like :weakmap_size, :length
+end
diff --git a/spec/ruby/core/objectspace/weakmap/member_spec.rb b/spec/ruby/core/objectspace/weakmap/member_spec.rb
new file mode 100644
index 0000000000..cefb190ce7
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/member_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/include'
+
+describe "ObjectSpace::WeakMap#member?" do
+  it_behaves_like :weakmap_include?, :member?
+end
diff --git a/spec/ruby/core/objectspace/weakmap/shared/each.rb b/spec/ruby/core/objectspace/weakmap/shared/each.rb
new file mode 100644
index 0000000000..771c416dde
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/shared/each.rb
@@ -0,0 +1,10 @@
+describe :weakmap_each, shared: true do
+  it "must take a block, except when empty" do
+    map = ObjectSpace::WeakMap.new
+    key = "a".upcase
+    ref = "x"
+    map.send(@method).should == map
+    map[key] = ref
+    -> { map.send(@method) }.should.raise(LocalJumpError)
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/shared/include.rb b/spec/ruby/core/objectspace/weakmap/shared/include.rb
new file mode 100644
index 0000000000..1770eeac8b
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/shared/include.rb
@@ -0,0 +1,30 @@
+describe :weakmap_include?, shared: true do
+  it "recognizes keys in use" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+
+    map[key1] = ref1
+    map.send(@method, key1).should == true
+    map[key1] = ref1
+    map.send(@method, key1).should == true
+    map[key2] = ref2
+    map.send(@method, key2).should == true
+  end
+
+  it "matches using identity semantics" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a a].map(&:upcase)
+    ref = "x"
+    map[key1] = ref
+    map.send(@method, key2).should == false
+  end
+
+  it "reports true if the pair exists and the value is nil" do
+    map = ObjectSpace::WeakMap.new
+    key = Object.new
+    map[key] = nil
+    map.size.should == 1
+    map.send(@method, key).should == true
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/shared/members.rb b/spec/ruby/core/objectspace/weakmap/shared/members.rb
new file mode 100644
index 0000000000..57226c8d7a
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/shared/members.rb
@@ -0,0 +1,14 @@
+describe :weakmap_members, shared: true do
+  it "is correct" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    @method.call(map).should == []
+    map[key1] = ref1
+    @method.call(map).should == @object[0..0]
+    map[key1] = ref1
+    @method.call(map).should == @object[0..0]
+    map[key2] = ref2
+    @method.call(map).sort.should == @object
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/shared/size.rb b/spec/ruby/core/objectspace/weakmap/shared/size.rb
new file mode 100644
index 0000000000..1064f99d1b
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/shared/size.rb
@@ -0,0 +1,14 @@
+describe :weakmap_size, shared: true do
+  it "is correct" do
+    map = ObjectSpace::WeakMap.new
+    key1, key2 = %w[a b].map(&:upcase)
+    ref1, ref2 = %w[x y]
+    map.send(@method).should == 0
+    map[key1] = ref1
+    map.send(@method).should == 1
+    map[key1] = ref1
+    map.send(@method).should == 1
+    map[key2] = ref2
+    map.send(@method).should == 2
+  end
+end
diff --git a/spec/ruby/core/objectspace/weakmap/size_spec.rb b/spec/ruby/core/objectspace/weakmap/size_spec.rb
new file mode 100644
index 0000000000..1446abaa24
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/size_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/size'
+
+describe "ObjectSpace::WeakMap#size" do
+  it_behaves_like :weakmap_size, :size
+end
diff --git a/spec/ruby/core/objectspace/weakmap/values_spec.rb b/spec/ruby/core/objectspace/weakmap/values_spec.rb
new file mode 100644
index 0000000000..6f6f90d0ba
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap/values_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/members'
+
+describe "ObjectSpace::WeakMap#values" do
+  it_behaves_like :weakmap_members, -> map { map.values }, %w[x y]
+end
diff --git a/spec/ruby/core/objectspace/weakmap_spec.rb b/spec/ruby/core/objectspace/weakmap_spec.rb
new file mode 100644
index 0000000000..2f3f93c291
--- /dev/null
+++ b/spec/ruby/core/objectspace/weakmap_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+
+describe "ObjectSpace::WeakMap" do
+
+  # Note that we can't really spec the most important aspect of this class: that entries get removed when the values
+  # become unreachable. This is because Ruby does not offer a way to reliable invoke GC (GC.start is not enough, neither
+  # on MRI or on alternative implementations).
+
+  it "includes Enumerable" do
+    ObjectSpace::WeakMap.include?(Enumerable).should == true
+  end
+end
diff --git a/spec/ruby/core/proc/allocate_spec.rb b/spec/ruby/core/proc/allocate_spec.rb
index 54e1b69df9..96c4eb9fa8 100644
--- a/spec/ruby/core/proc/allocate_spec.rb
+++ b/spec/ruby/core/proc/allocate_spec.rb
@@ -4,6 +4,6 @@ describe "Proc.allocate" do
   it "raises a TypeError" do
     -> {
       Proc.allocate
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/proc/arity_spec.rb b/spec/ruby/core/proc/arity_spec.rb
index f7cb5ad0f8..5c7728cb30 100644
--- a/spec/ruby/core/proc/arity_spec.rb
+++ b/spec/ruby/core/proc/arity_spec.rb
@@ -268,6 +268,14 @@ describe "Proc#arity" do
         @a.arity.should == 3
         @b.arity.should == 3
       end
+
+      # implicit rest
+      evaluate <<-ruby do
+          @a = lambda { |a, | }
+      ruby
+
+        @a.arity.should == 1
+      end
     end
 
     context "returns negative values" do
@@ -530,6 +538,14 @@ describe "Proc#arity" do
         @a.arity.should == 1
         @b.arity.should == 5
       end
+
+      # implicit rest
+      evaluate <<-ruby do
+          @a = proc { |a, | }
+      ruby
+
+        @a.arity.should == 1
+      end
     end
 
     context "returns negative values" do
diff --git a/spec/ruby/core/proc/binding_spec.rb b/spec/ruby/core/proc/binding_spec.rb
index 86ab6bd400..d643cbf89c 100644
--- a/spec/ruby/core/proc/binding_spec.rb
+++ b/spec/ruby/core/proc/binding_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Proc#binding" do
   it "returns a Binding instance" do
     [Proc.new{}, -> {}, proc {}].each { |p|
-      p.binding.should be_kind_of(Binding)
+      p.binding.should.is_a?(Binding)
     }
   end
 
diff --git a/spec/ruby/core/proc/block_pass_spec.rb b/spec/ruby/core/proc/block_pass_spec.rb
index 99255139d4..82c08db8a7 100644
--- a/spec/ruby/core/proc/block_pass_spec.rb
+++ b/spec/ruby/core/proc/block_pass_spec.rb
@@ -8,36 +8,14 @@ describe "Proc as a block pass argument" do
   it "remains the same object if re-vivified by the target method" do
     p = Proc.new {}
     p2 = revivify(&p)
-    p.should equal p2
+    p.should.equal? p2
     p.should == p2
   end
 
   it "remains the same object if reconstructed with Proc.new" do
     p = Proc.new {}
     p2 = Proc.new(&p)
-    p.should equal p2
+    p.should.equal? p2
     p.should == p2
   end
 end
-
-ruby_version_is ""..."2.7" do
-  describe "Proc as an implicit block pass argument" do
-    def revivify
-      Proc.new
-    end
-
-    it "remains the same object if re-vivified by the target method" do
-      p = Proc.new {}
-      p2 = revivify(&p)
-      p.should equal p2
-      p.should == p2
-    end
-
-    it "remains the same object if reconstructed with Proc.new" do
-      p = Proc.new {}
-      p2 = Proc.new(&p)
-      p.should equal p2
-      p.should == p2
-    end
-  end
-end
diff --git a/spec/ruby/core/proc/clone_spec.rb b/spec/ruby/core/proc/clone_spec.rb
index a1a1292654..aee4873e09 100644
--- a/spec/ruby/core/proc/clone_spec.rb
+++ b/spec/ruby/core/proc/clone_spec.rb
@@ -1,6 +1,28 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 require_relative 'shared/dup'
 
 describe "Proc#clone" do
   it_behaves_like :proc_dup, :clone
+
+  ruby_bug "cloning a frozen proc is broken on Ruby 3.3", ""..."3.4" do
+    it "preserves frozen status" do
+      proc = Proc.new { }
+      proc.freeze
+      proc.frozen?.should == true
+      proc.clone.frozen?.should == true
+    end
+  end
+
+  it "calls #initialize_clone on subclass" do
+    obj = ProcSpecs::MyProc2.new(:a, 2) { }
+    dup = obj.clone
+
+    dup.should_not.equal?(obj)
+    dup.class.should == ProcSpecs::MyProc2
+
+    dup.first.should == :a
+    dup.second.should == 2
+    dup.initializer.should == :clone
+  end
 end
diff --git a/spec/ruby/core/proc/compose_spec.rb b/spec/ruby/core/proc/compose_spec.rb
index 35e949a779..9e9b57e06f 100644
--- a/spec/ruby/core/proc/compose_spec.rb
+++ b/spec/ruby/core/proc/compose_spec.rb
@@ -1,110 +1,142 @@
 require_relative '../../spec_helper'
 require_relative 'shared/compose'
 
-ruby_version_is "2.6" do
-  describe "Proc#<<" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = proc { |s| s.succ }
+describe "Proc#<<" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = proc { |s| s.succ }
 
-      (succ << upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ << upcase).call('Ruby').should == "RUBZ"
+  end
+
+  it "calls passed Proc with arguments and then calls self with result" do
+    f = proc { |x| x * x }
+    g = proc { |x| x + x }
+
+    (f << g).call(2).should == 16
+    (g << f).call(2).should == 8
+  end
+
+  it "accepts any callable object" do
+    inc = proc { |n| n + 1 }
+
+    double = Object.new
+    def double.call(n); n * 2; end
+
+    (inc << double).call(3).should == 7
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
+  it_behaves_like :proc_compose, :<<, -> { proc { |s| s.upcase } }
+
+  describe "composition" do
+    it "is a Proc" do
       f = proc { |x| x * x }
       g = proc { |x| x + x }
 
-      (f << g).call(2).should == 16
-      (g << f).call(2).should == 8
+      (f << g).is_a?(Proc).should == true
+      (f << g).should_not.lambda?
     end
 
-    it "accepts any callable object" do
-      inc = proc { |n| n + 1 }
+    it "is a lambda when parameter is lambda" do
+      f = -> x { x * x }
+      g = proc { |x| x + x }
+      lambda_proc = -> x { x }
+
+      # lambda << proc
+      (f << g).is_a?(Proc).should == true
+      (f << g).should_not.lambda?
 
-      double = Object.new
-      def double.call(n); n * 2; end
+      # lambda << lambda
+      (f << lambda_proc).is_a?(Proc).should == true
+      (f << lambda_proc).should.lambda?
 
-      (inc << double).call(3).should == 7
+      # proc << lambda
+      (g << f).is_a?(Proc).should == true
+      (g << f).should.lambda?
     end
 
-    it_behaves_like :proc_compose, :<<, -> { proc { |s| s.upcase } }
+    it "may accept multiple arguments" do
+      inc = proc { |n| n + 1 }
+      mul = proc { |n, m| n * m }
 
-    describe "composition" do
-      it "is a Proc" do
-        f = proc { |x| x * x }
-        g = proc { |x| x + x }
+      (inc << mul).call(2, 3).should == 7
+    end
 
-        (f << g).is_a?(Proc).should == true
-        (f << g).lambda?.should == false
-      end
+    it "passes blocks to the second proc" do
+      ScratchPad.record []
+      one = proc { |&arg| arg.call :one if arg }
+      two = proc { |&arg| arg.call :two if arg }
+      (one << two).call { |x| ScratchPad << x }
+      ScratchPad.recorded.should == [:two]
+    end
+  end
+end
+
+describe "Proc#>>" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = proc { |s| s.succ }
 
-      it "may accept multiple arguments" do
-        inc = proc { |n| n + 1 }
-        mul = proc { |n, m| n * m }
+    (succ >> upcase).call('Ruby').should == "RUBZ"
+  end
 
-        (inc << mul).call(2, 3).should == 7
-      end
+  it "calls passed Proc with arguments and then calls self with result" do
+    f = proc { |x| x * x }
+    g = proc { |x| x + x }
 
-      it "passes blocks to the second proc" do
-        ScratchPad.record []
-        one = proc { |&arg| arg.call :one if arg }
-        two = proc { |&arg| arg.call :two if arg }
-        (one << two).call { |x| ScratchPad << x }
-        ScratchPad.recorded.should == [:two]
-      end
-    end
+    (f >> g).call(2).should == 8
+    (g >> f).call(2).should == 16
   end
 
-  describe "Proc#>>" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = proc { |s| s.succ }
+  it "accepts any callable object" do
+    inc = proc { |n| n + 1 }
 
-      (succ >> upcase).call('Ruby').should == "RUBZ"
-    end
+    double = Object.new
+    def double.call(n); n * 2; end
+
+    (inc >> double).call(3).should == 8
+  end
+
+  it_behaves_like :proc_compose, :>>, -> { proc { |s| s.upcase } }
 
-    it "calls passed Proc with arguments and then calls self with result" do
+  describe "composition" do
+    it "is a Proc" do
       f = proc { |x| x * x }
       g = proc { |x| x + x }
 
-      (f >> g).call(2).should == 8
-      (g >> f).call(2).should == 16
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should_not.lambda?
     end
 
-    it "accepts any callable object" do
-      inc = proc { |n| n + 1 }
-
-      double = Object.new
-      def double.call(n); n * 2; end
+    it "is a Proc when other is lambda" do
+      f = proc { |x| x * x }
+      g = -> x { x + x }
 
-      (inc >> double).call(3).should == 8
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should_not.lambda?
     end
 
-    it_behaves_like :proc_compose, :>>, -> { proc { |s| s.upcase } }
-
-    describe "composition" do
-      it "is a Proc" do
-        f = proc { |x| x * x }
-        g = proc { |x| x + x }
+    it "is a lambda when self is lambda" do
+      f = -> x { x * x }
+      g = proc { |x| x + x }
 
-        (f >> g).is_a?(Proc).should == true
-        (f >> g).lambda?.should == false
-      end
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should.lambda?
+    end
 
-      it "may accept multiple arguments" do
-        inc = proc { |n| n + 1 }
-        mul = proc { |n, m| n * m }
+    it "may accept multiple arguments" do
+      inc = proc { |n| n + 1 }
+      mul = proc { |n, m| n * m }
 
-        (mul >> inc).call(2, 3).should == 7
-      end
+      (mul >> inc).call(2, 3).should == 7
+    end
 
-      it "passes blocks to the first proc" do
-        ScratchPad.record []
-        one = proc { |&arg| arg.call :one if arg }
-        two = proc { |&arg| arg.call :two if arg }
-        (one >> two).call { |x| ScratchPad << x }
-        ScratchPad.recorded.should == [:one]
-      end
+    it "passes blocks to the first proc" do
+      ScratchPad.record []
+      one = proc { |&arg| arg.call :one if arg }
+      two = proc { |&arg| arg.call :two if arg }
+      (one >> two).call { |x| ScratchPad << x }
+      ScratchPad.recorded.should == [:one]
     end
   end
 end
diff --git a/spec/ruby/core/proc/curry_spec.rb b/spec/ruby/core/proc/curry_spec.rb
index 24df2a8a72..de13983ca6 100644
--- a/spec/ruby/core/proc/curry_spec.rb
+++ b/spec/ruby/core/proc/curry_spec.rb
@@ -8,12 +8,12 @@ describe "Proc#curry" do
 
   it "returns a Proc when called on a proc" do
     p = proc { true }
-    p.curry.should be_an_instance_of(Proc)
+    p.curry.should.instance_of?(Proc)
   end
 
   it "returns a Proc when called on a lambda" do
     p = -> { true }
-    p.curry.should be_an_instance_of(Proc)
+    p.curry.should.instance_of?(Proc)
   end
 
   it "calls the curried proc with the arguments if sufficient arguments have been given" do
@@ -23,11 +23,11 @@ describe "Proc#curry" do
 
   it "returns a Proc that consumes the remainder of the arguments unless sufficient arguments have been given" do
     proc2 = @proc_add.curry[1][2]
-    proc2.should be_an_instance_of(Proc)
+    proc2.should.instance_of?(Proc)
     proc2.call(3).should == 6
 
     lambda2 = @lambda_add.curry[1][2]
-    lambda2.should be_an_instance_of(Proc)
+    lambda2.should.instance_of?(Proc)
     lambda2.call(3).should == 6
 
     @proc_add.curry.call(1,2,3).should == 6
@@ -36,10 +36,10 @@ describe "Proc#curry" do
 
   it "can be called multiple times on the same Proc" do
     @proc_add.curry
-    -> { @proc_add.curry }.should_not raise_error
+    -> { @proc_add.curry }.should_not.raise
 
     @lambda_add.curry
-    -> { @lambda_add.curry }.should_not raise_error
+    -> { @lambda_add.curry }.should_not.raise
   end
 
   it "can be passed superfluous arguments if created from a proc" do
@@ -49,8 +49,8 @@ describe "Proc#curry" do
   end
 
   it "raises an ArgumentError if passed superfluous arguments when created from a lambda" do
-    -> { @lambda_add.curry[1,2,3,4] }.should raise_error(ArgumentError)
-    -> { @lambda_add.curry[1,2].curry[3,4,5,6] }.should raise_error(ArgumentError)
+    -> { @lambda_add.curry[1,2,3,4] }.should.raise(ArgumentError)
+    -> { @lambda_add.curry[1,2].curry[3,4,5,6] }.should.raise(ArgumentError)
   end
 
   it "returns Procs with arities of -1" do
@@ -63,7 +63,7 @@ describe "Proc#curry" do
   it "produces Procs that raise ArgumentError for #binding" do
     -> do
       @proc_add.curry.binding
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "produces Procs that return [[:rest]] for #parameters" do
@@ -98,41 +98,41 @@ describe "Proc#curry with arity argument" do
   end
 
   it "accepts an optional Integer argument for the arity" do
-    -> { @proc_add.curry(3) }.should_not raise_error
-    -> { @lambda_add.curry(3) }.should_not raise_error
+    -> { @proc_add.curry(3) }.should_not.raise
+    -> { @lambda_add.curry(3) }.should_not.raise
   end
 
   it "returns a Proc when called on a proc" do
-    @proc_add.curry(3).should be_an_instance_of(Proc)
+    @proc_add.curry(3).should.instance_of?(Proc)
   end
 
   it "returns a Proc when called on a lambda" do
-    @lambda_add.curry(3).should be_an_instance_of(Proc)
+    @lambda_add.curry(3).should.instance_of?(Proc)
   end
 
   # [ruby-core:24127]
   it "retains the lambda-ness of the Proc on which its called" do
-    @lambda_add.curry(3).lambda?.should be_true
-    @proc_add.curry(3).lambda?.should be_false
+    @lambda_add.curry(3).lambda?.should == true
+    @proc_add.curry(3).lambda?.should == false
   end
 
   it "raises an ArgumentError if called on a lambda that requires more than _arity_ arguments" do
-    -> { @lambda_add.curry(2) }.should raise_error(ArgumentError)
-    -> { -> x, y, z, *more{}.curry(2) }.should raise_error(ArgumentError)
+    -> { @lambda_add.curry(2) }.should.raise(ArgumentError)
+    -> { -> x, y, z, *more{}.curry(2) }.should.raise(ArgumentError)
   end
 
   it 'returns a Proc if called on a lambda that requires fewer than _arity_ arguments but may take more' do
-    -> a, b, c, d=nil, e=nil {}.curry(4).should be_an_instance_of(Proc)
-    -> a, b, c, d=nil, *e {}.curry(4).should be_an_instance_of(Proc)
-    -> a, b, c, *d {}.curry(4).should be_an_instance_of(Proc)
+    -> a, b, c, d=nil, e=nil {}.curry(4).should.instance_of?(Proc)
+    -> a, b, c, d=nil, *e {}.curry(4).should.instance_of?(Proc)
+    -> a, b, c, *d {}.curry(4).should.instance_of?(Proc)
   end
 
   it "raises an ArgumentError if called on a lambda that requires fewer than _arity_ arguments" do
-    -> { @lambda_add.curry(4) }.should raise_error(ArgumentError)
-    -> { -> { true }.curry(1) }.should raise_error(ArgumentError)
-    -> { -> a, b=nil {}.curry(5) }.should raise_error(ArgumentError)
-    -> { -> a, &b {}.curry(2) }.should raise_error(ArgumentError)
-    -> { -> a, b=nil, &c {}.curry(3) }.should raise_error(ArgumentError)
+    -> { @lambda_add.curry(4) }.should.raise(ArgumentError)
+    -> { -> { true }.curry(1) }.should.raise(ArgumentError)
+    -> { -> a, b=nil {}.curry(5) }.should.raise(ArgumentError)
+    -> { -> a, &b {}.curry(2) }.should.raise(ArgumentError)
+    -> { -> a, b=nil, &c {}.curry(3) }.should.raise(ArgumentError)
   end
 
   it "calls the curried proc with the arguments if _arity_ arguments have been given" do
@@ -142,32 +142,31 @@ describe "Proc#curry with arity argument" do
 
   it "returns a Proc that consumes the remainder of the arguments when fewer than _arity_ arguments are given" do
     proc2 = @proc_add.curry(3)[1][2]
-    proc2.should be_an_instance_of(Proc)
+    proc2.should.instance_of?(Proc)
     proc2.call(3).should == 6
 
     lambda2 = @lambda_add.curry(3)[1][2]
-    lambda2.should be_an_instance_of(Proc)
+    lambda2.should.instance_of?(Proc)
     lambda2.call(3).should == 6
   end
 
   it "can be specified multiple times on the same Proc" do
     @proc_add.curry(2)
-    -> { @proc_add.curry(1) }.should_not raise_error
+    -> { @proc_add.curry(1) }.should_not.raise
 
     @lambda_add.curry(3)
-    -> { @lambda_add.curry(3) }.should_not raise_error
+    -> { @lambda_add.curry(3) }.should_not.raise
   end
 
   it "can be passed more than _arity_ arguments if created from a proc" do
-    -> { @proc_add.curry(3)[1,2,3,4].should == 6 }.should_not
-      raise_error(ArgumentError)
-    -> { @proc_add.curry(1)[1,2].curry(3)[3,4,5,6].should == 6 }.should_not
-      raise_error(ArgumentError)
+    @proc_add.curry(3)[1,2,3,4].should == 6
+
+    @proc_add.curry(3)[1,2].curry(3)[3,4,5,6].should == 6
   end
 
   it "raises an ArgumentError if passed more than _arity_ arguments when created from a lambda" do
-    -> { @lambda_add.curry(3)[1,2,3,4] }.should raise_error(ArgumentError)
-    -> { @lambda_add.curry(1)[1,2].curry(3)[3,4,5,6] }.should raise_error(ArgumentError)
+    -> { @lambda_add.curry(3)[1,2,3,4] }.should.raise(ArgumentError)
+    -> { @lambda_add.curry(3)[1,2].curry(3)[3,4,5,6] }.should.raise(ArgumentError)
   end
 
   it "returns Procs with arities of -1 regardless of the value of _arity_" do
diff --git a/spec/ruby/core/proc/dup_spec.rb b/spec/ruby/core/proc/dup_spec.rb
index 6da2f3080c..8604389422 100644
--- a/spec/ruby/core/proc/dup_spec.rb
+++ b/spec/ruby/core/proc/dup_spec.rb
@@ -1,6 +1,26 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/common'
 require_relative 'shared/dup'
 
 describe "Proc#dup" do
   it_behaves_like :proc_dup, :dup
+
+  it "resets frozen status" do
+    proc = Proc.new { }
+    proc.freeze
+    proc.frozen?.should == true
+    proc.dup.frozen?.should == false
+  end
+
+  it "calls #initialize_dup on subclass" do
+    obj = ProcSpecs::MyProc2.new(:a, 2) { }
+    dup = obj.dup
+
+    dup.should_not.equal?(obj)
+    dup.class.should == ProcSpecs::MyProc2
+
+    dup.first.should == :a
+    dup.second.should == 2
+    dup.initializer.should == :dup
+  end
 end
diff --git a/spec/ruby/core/proc/element_reference_spec.rb b/spec/ruby/core/proc/element_reference_spec.rb
index 9077e44c34..ea3a915a11 100644
--- a/spec/ruby/core/proc/element_reference_spec.rb
+++ b/spec/ruby/core/proc/element_reference_spec.rb
@@ -17,11 +17,11 @@ describe "Proc#call on a Proc created with Kernel#lambda or Kernel#proc" do
   it_behaves_like :proc_call_on_proc_or_lambda, :call
 end
 
-describe "Proc#[] with frozen_string_literals" do
+describe "Proc#[] with frozen_string_literal: true/false" do
   it "doesn't duplicate frozen strings" do
-    ProcArefSpecs.aref.frozen?.should be_false
-    ProcArefSpecs.aref_freeze.frozen?.should be_true
-    ProcArefFrozenSpecs.aref.frozen?.should be_true
-    ProcArefFrozenSpecs.aref_freeze.frozen?.should be_true
+    ProcArefSpecs.aref.frozen?.should == false
+    ProcArefSpecs.aref_freeze.frozen?.should == true
+    ProcArefFrozenSpecs.aref.frozen?.should == true
+    ProcArefFrozenSpecs.aref_freeze.frozen?.should == true
   end
 end
diff --git a/spec/ruby/core/proc/eql_spec.rb b/spec/ruby/core/proc/eql_spec.rb
index a3c5a5658d..ad8f6749fc 100644
--- a/spec/ruby/core/proc/eql_spec.rb
+++ b/spec/ruby/core/proc/eql_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/equal'
 
 describe "Proc#eql?" do
-  it_behaves_like :proc_equal_undefined, :eql?
+  it_behaves_like :proc_equal, :eql?
 end
diff --git a/spec/ruby/core/proc/equal_value_spec.rb b/spec/ruby/core/proc/equal_value_spec.rb
index 1b6ac792cf..ec7f274732 100644
--- a/spec/ruby/core/proc/equal_value_spec.rb
+++ b/spec/ruby/core/proc/equal_value_spec.rb
@@ -2,5 +2,5 @@ require_relative '../../spec_helper'
 require_relative 'shared/equal'
 
 describe "Proc#==" do
-  it_behaves_like :proc_equal_undefined, :==
+  it_behaves_like :proc_equal, :==
 end
diff --git a/spec/ruby/core/proc/fixtures/common.rb b/spec/ruby/core/proc/fixtures/common.rb
index 6e27a2dee7..dfe67d7ba8 100644
--- a/spec/ruby/core/proc/fixtures/common.rb
+++ b/spec/ruby/core/proc/fixtures/common.rb
@@ -32,7 +32,28 @@ module ProcSpecs
       @second = b
     end
 
-    attr_reader :first, :second
+    attr_reader :first, :second, :initializer
+
+    def initialize_copy(other)
+      super
+      @initializer = :copy
+      @first = other.first
+      @second = other.second
+    end
+
+    def initialize_dup(other)
+      super
+      @initializer = :dup
+      @first = other.first
+      @second = other.second
+    end
+
+    def initialize_clone(other, **options)
+      super
+      @initializer = :clone
+      @first = other.first
+      @second = other.second
+    end
   end
 
   class Arity
diff --git a/spec/ruby/core/proc/fixtures/proc_aref.rb b/spec/ruby/core/proc/fixtures/proc_aref.rb
index a305667797..8ee355b14c 100644
--- a/spec/ruby/core/proc/fixtures/proc_aref.rb
+++ b/spec/ruby/core/proc/fixtures/proc_aref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module ProcArefSpecs
   def self.aref
     proc {|a| a }["sometext"]
diff --git a/spec/ruby/core/proc/fixtures/source_location.rb b/spec/ruby/core/proc/fixtures/source_location.rb
index 688dac1e22..5572094630 100644
--- a/spec/ruby/core/proc/fixtures/source_location.rb
+++ b/spec/ruby/core/proc/fixtures/source_location.rb
@@ -44,7 +44,7 @@ module ProcSpecs
 
     def self.my_detached_lambda
       body = -> { true }
-      lambda(&body)
+      suppress_warning {lambda(&body)}
     end
 
     def self.my_detached_proc_new
diff --git a/spec/ruby/core/proc/hash_spec.rb b/spec/ruby/core/proc/hash_spec.rb
index d780c1ceb0..adcb1ccb78 100644
--- a/spec/ruby/core/proc/hash_spec.rb
+++ b/spec/ruby/core/proc/hash_spec.rb
@@ -2,12 +2,12 @@ require_relative '../../spec_helper'
 
 describe "Proc#hash" do
   it "is provided" do
-    proc {}.respond_to?(:hash).should be_true
-    -> {}.respond_to?(:hash).should be_true
+    proc {}.respond_to?(:hash).should == true
+    -> {}.respond_to?(:hash).should == true
   end
 
   it "returns an Integer" do
-    proc { 1 + 489 }.hash.should be_kind_of(Fixnum)
+    proc { 1 + 489 }.hash.should.is_a?(Integer)
   end
 
   it "is stable" do
diff --git a/spec/ruby/core/proc/lambda_spec.rb b/spec/ruby/core/proc/lambda_spec.rb
index fe2ceb4279..1ff6147319 100644
--- a/spec/ruby/core/proc/lambda_spec.rb
+++ b/spec/ruby/core/proc/lambda_spec.rb
@@ -3,58 +3,53 @@ require_relative 'fixtures/common'
 
 describe "Proc#lambda?" do
   it "returns true if the Proc was created from a block with the lambda keyword" do
-    -> {}.lambda?.should be_true
+    -> {}.lambda?.should == true
   end
 
   it "returns false if the Proc was created from a block with the proc keyword" do
-    proc {}.lambda?.should be_false
+    proc {}.lambda?.should == false
   end
 
   it "returns false if the Proc was created from a block with Proc.new" do
-    Proc.new {}.lambda?.should be_false
-  end
-
-  it "is preserved when passing a Proc with & to the lambda keyword" do
-    lambda(&->{}).lambda?.should be_true
-    lambda(&proc{}).lambda?.should be_false
+    Proc.new {}.lambda?.should == false
   end
 
   it "is preserved when passing a Proc with & to the proc keyword" do
-    proc(&->{}).lambda?.should be_true
-    proc(&proc{}).lambda?.should be_false
+    proc(&->{}).lambda?.should == true
+    proc(&proc{}).lambda?.should == false
   end
 
   it "is preserved when passing a Proc with & to Proc.new" do
-    Proc.new(&->{}).lambda?.should be_true
-    Proc.new(&proc{}).lambda?.should be_false
+    Proc.new(&->{}).lambda?.should == true
+    Proc.new(&proc{}).lambda?.should == false
   end
 
   it "returns false if the Proc was created from a block with &" do
-    ProcSpecs.new_proc_from_amp{}.lambda?.should be_false
+    ProcSpecs.new_proc_from_amp{}.lambda?.should == false
   end
 
   it "is preserved when the Proc was passed using &" do
-    ProcSpecs.new_proc_from_amp(&->{}).lambda?.should be_true
-    ProcSpecs.new_proc_from_amp(&proc{}).lambda?.should be_false
-    ProcSpecs.new_proc_from_amp(&Proc.new{}).lambda?.should be_false
+    ProcSpecs.new_proc_from_amp(&->{}).lambda?.should == true
+    ProcSpecs.new_proc_from_amp(&proc{}).lambda?.should == false
+    ProcSpecs.new_proc_from_amp(&Proc.new{}).lambda?.should == false
   end
 
   it "returns true for a Method converted to a Proc" do
     m = :foo.method(:to_s)
-    m.to_proc.lambda?.should be_true
-    ProcSpecs.new_proc_from_amp(&m).lambda?.should be_true
+    m.to_proc.lambda?.should == true
+    ProcSpecs.new_proc_from_amp(&m).lambda?.should == true
   end
 
   # [ruby-core:24127]
   it "is preserved when a Proc is curried" do
-    ->{}.curry.lambda?.should be_true
-    proc{}.curry.lambda?.should be_false
-    Proc.new{}.curry.lambda?.should be_false
+    ->{}.curry.lambda?.should == true
+    proc{}.curry.lambda?.should == false
+    Proc.new{}.curry.lambda?.should == false
   end
 
   it "is preserved when a curried Proc is called without enough arguments" do
-    -> x, y{}.curry.call(42).lambda?.should be_true
-    proc{|x,y|}.curry.call(42).lambda?.should be_false
-    Proc.new{|x,y|}.curry.call(42).lambda?.should be_false
+    -> x, y{}.curry.call(42).lambda?.should == true
+    proc{|x,y|}.curry.call(42).lambda?.should == false
+    Proc.new{|x,y|}.curry.call(42).lambda?.should == false
   end
 end
diff --git a/spec/ruby/core/proc/new_spec.rb b/spec/ruby/core/proc/new_spec.rb
index cc033467e5..f0b817f0cb 100644
--- a/spec/ruby/core/proc/new_spec.rb
+++ b/spec/ruby/core/proc/new_spec.rb
@@ -71,7 +71,7 @@ describe "Proc.new with an associated block" do
     end
     res = some_method()
 
-    -> { res.call }.should raise_error(LocalJumpError)
+    -> { res.call }.should.raise(LocalJumpError)
   end
 
   it "returns from within enclosing method when 'return' is used in the block" do
@@ -86,7 +86,7 @@ describe "Proc.new with an associated block" do
 
   it "returns a subclass of Proc" do
     obj = ProcSpecs::MyProc.new { }
-    obj.should be_kind_of(ProcSpecs::MyProc)
+    obj.should.is_a?(ProcSpecs::MyProc)
   end
 
   it "calls initialize on the Proc object" do
@@ -94,20 +94,6 @@ describe "Proc.new with an associated block" do
     obj.first.should == :a
     obj.second.should == 2
   end
-
-  ruby_version_is ""..."2.7" do
-    it "returns a new Proc instance from the block passed to the containing method" do
-      prc = ProcSpecs.new_proc_in_method { "hello" }
-      prc.should be_an_instance_of(Proc)
-      prc.call.should == "hello"
-    end
-
-    it "returns a new Proc instance from the block passed to the containing method" do
-      prc = ProcSpecs.new_proc_subclass_in_method { "hello" }
-      prc.should be_an_instance_of(ProcSpecs::ProcSubclass)
-      prc.call.should == "hello"
-    end
-  end
 end
 
 describe "Proc.new with a block argument" do
@@ -115,7 +101,7 @@ describe "Proc.new with a block argument" do
     passed_prc = Proc.new { "hello".size }
     prc = Proc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call.should == 5
   end
 
@@ -124,7 +110,7 @@ describe "Proc.new with a block argument" do
     passed_prc = Proc.new(&method)
     prc = Proc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call.should == 5
   end
 
@@ -132,7 +118,7 @@ describe "Proc.new with a block argument" do
     passed_prc = Proc.new(&:size)
     prc = Proc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call("hello").should == 5
   end
 end
@@ -143,7 +129,7 @@ describe "Proc.new with a block argument called indirectly from a subclass" do
     passed_prc.class.should == ProcSpecs::MyProc
     prc = ProcSpecs::MyProc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call.should == 5
   end
 
@@ -153,7 +139,7 @@ describe "Proc.new with a block argument called indirectly from a subclass" do
     passed_prc.class.should == ProcSpecs::MyProc
     prc = ProcSpecs::MyProc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call.should == 5
   end
 
@@ -162,65 +148,31 @@ describe "Proc.new with a block argument called indirectly from a subclass" do
     passed_prc.class.should == ProcSpecs::MyProc
     prc = ProcSpecs::MyProc.new(&passed_prc)
 
-    prc.should equal(passed_prc)
+    prc.should.equal?(passed_prc)
     prc.call("hello").should == 5
   end
 end
 
 describe "Proc.new without a block" do
   it "raises an ArgumentError" do
-    -> { Proc.new }.should raise_error(ArgumentError)
+    -> { Proc.new }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if invoked from within a method with no block" do
-    -> { ProcSpecs.new_proc_in_method }.should raise_error(ArgumentError)
+    -> { ProcSpecs.new_proc_in_method }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if invoked on a subclass from within a method with no block" do
-    -> { ProcSpecs.new_proc_subclass_in_method }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is ""..."2.7" do
-    it "uses the implicit block from an enclosing method" do
-      def some_method
-        Proc.new
-      end
-
-      prc = some_method { "hello" }
-
-      prc.call.should == "hello"
-    end
-
-    it "uses the implicit block from an enclosing method when called inside a block" do
-      def some_method
-        proc do |&block|
-          Proc.new
-        end.call { "failing" }
-      end
-      prc = some_method { "hello" }
-
-      prc.call.should == "hello"
-    end
+    -> { ProcSpecs.new_proc_subclass_in_method }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.7" do
-    it "can be created if invoked from within a method with a block" do
-      -> { ProcSpecs.new_proc_in_method { "hello" } }.should complain(/Capturing the given block using Proc.new is deprecated/)
-    end
-
-    it "can be created if invoked on a subclass from within a method with a block" do
-      -> { ProcSpecs.new_proc_subclass_in_method { "hello" } }.should complain(/Capturing the given block using Proc.new is deprecated/)
+  it "raises an ArgumentError when passed no block" do
+    def some_method
+      Proc.new
     end
 
-
-    it "can be create when called with no block" do
-      def some_method
-        Proc.new
-      end
-
-      -> {
-        some_method { "hello" }
-      }.should complain(/Capturing the given block using Proc.new is deprecated/)
-    end
+    -> { ProcSpecs.new_proc_in_method { "hello" } }.should.raise(ArgumentError, 'tried to create Proc object without a block')
+    -> { ProcSpecs.new_proc_subclass_in_method { "hello" } }.should.raise(ArgumentError, 'tried to create Proc object without a block')
+    -> { some_method { "hello" } }.should.raise(ArgumentError, 'tried to create Proc object without a block')
   end
 end
diff --git a/spec/ruby/core/proc/parameters_spec.rb b/spec/ruby/core/proc/parameters_spec.rb
index 2bc5f1325c..ac8c6e3560 100644
--- a/spec/ruby/core/proc/parameters_spec.rb
+++ b/spec/ruby/core/proc/parameters_spec.rb
@@ -7,8 +7,8 @@ describe "Proc#parameters" do
 
   it "returns an Array of Arrays for a proc expecting parameters" do
     p = proc {|x| }
-    p.parameters.should be_an_instance_of(Array)
-    p.parameters.first.should be_an_instance_of(Array)
+    p.parameters.should.instance_of?(Array)
+    p.parameters.first.should.instance_of?(Array)
   end
 
   it "sets the first element of each sub-Array to :opt for optional arguments" do
@@ -20,6 +20,29 @@ describe "Proc#parameters" do
     proc {|x| }.parameters.first.first.should == :opt
   end
 
+  it "sets the first element of each sub-Array to :req for required argument if lambda keyword used" do
+    proc {|x| }.parameters(lambda: true).first.first.should == :req
+    proc {|y,*x| }.parameters(lambda: true).first.first.should == :req
+  end
+
+  it "regards named parameters in procs as required if lambda keyword used" do
+    proc {|x| }.parameters(lambda: true).first.first.should == :req
+  end
+
+  it "regards named parameters in lambda as optional if lambda: false keyword used" do
+    -> x { }.parameters(lambda: false).first.first.should == :opt
+  end
+
+  it "regards named parameters in procs and lambdas as required if lambda keyword is truthy" do
+    proc {|x| }.parameters(lambda: 123).first.first.should == :req
+    -> x { }.parameters(lambda: 123).first.first.should == :req
+  end
+
+  it "ignores the lambda keyword if it is nil" do
+    proc {|x|}.parameters(lambda: nil).first.first.should == :opt
+    -> x { }.parameters(lambda: nil).first.first.should == :req
+  end
+
   it "regards optional keyword parameters in procs as optional" do
     proc {|x: :y| }.parameters.first.first.should == :key
   end
@@ -39,7 +62,7 @@ describe "Proc#parameters" do
   end
 
   it "regards keyword parameters in lambdas as required" do
-    eval("lambda {|x:| }").parameters.first.first.should == :keyreq
+    -> x: { }.parameters.first.first.should == :keyreq
   end
 
   it "sets the first element of each sub-Array to :rest for parameters prefixed with asterisks" do
@@ -57,7 +80,7 @@ describe "Proc#parameters" do
   end
 
   it "sets the first element of each sub-Array to :block for parameters prefixed with ampersands" do
-    ->&x { }.parameters.first.first.should == :block
+    -> &x { }.parameters.first.first.should == :block
     -> x, &y { }.parameters.last.first.should == :block
     proc {|&x| }.parameters.first.first.should == :block
     proc {|x,&y| }.parameters.last.first.should == :block
@@ -68,7 +91,7 @@ describe "Proc#parameters" do
     -> x=Math::PI { }.parameters.first.last.should == :x
     -> an_argument, glark, &foo { }.parameters[1].last.should == :glark
     -> *rest { }.parameters.first.last.should == :rest
-    ->&block { }.parameters.first.last.should == :block
+    -> &block { }.parameters.first.last.should == :block
     proc {|x| }.parameters.first.last.should == :x
     proc {|x=Math::PI| }.parameters.first.last.should == :x
     proc {|an_argument, glark, &foo| }.parameters[1].last.should == :glark
@@ -76,12 +99,25 @@ describe "Proc#parameters" do
     proc {|&block| }.parameters.first.last.should == :block
   end
 
-  it "ignores unnamed rest args" do
+  it "ignores unnamed rest arguments" do
     -> x {}.parameters.should == [[:req, :x]]
   end
 
-  it "adds nameless rest arg for \"star\" argument" do
-    -> x, * {}.parameters.should == [[:req, :x], [:rest]]
+  it "ignores implicit rest arguments" do
+    proc { |x, | }.parameters.should == [[:opt, :x]]
+    -> x { }.parameters.should == [[:req, :x]]
+  end
+
+  it "adds rest arg with name * for \"star\" argument" do
+    -> * {}.parameters.should == [[:rest, :*]]
+  end
+
+  it "adds keyrest arg with ** as a name for \"double star\" argument" do
+    -> ** {}.parameters.should == [[:keyrest, :**]]
+  end
+
+  it "adds block arg with name & for anonymous block argument" do
+    -> & {}.parameters.should == [[:block, :&]]
   end
 
   it "does not add locals as block options with a block and splat" do
@@ -92,4 +128,56 @@ describe "Proc#parameters" do
       local_is_not_parameter = {}
     end.parameters.should == [[:rest, :args], [:block, :blk]]
   end
+
+  it "returns all parameters defined with the name _ as _" do
+    proc = proc {|_, _, _ = 1, *_, _:, _: 2, **_, &_| }
+    proc.parameters.should == [
+      [:opt, :_],
+      [:opt, :_],
+      [:opt, :_],
+      [:rest, :_],
+      [:keyreq, :_],
+      [:key, :_],
+      [:keyrest, :_],
+      [:block, :_]
+    ]
+
+    lambda = -> _, _, _ = 1, *_, _:, _: 2, **_, &_ {}
+    lambda.parameters.should == [
+      [:req, :_],
+      [:req, :_],
+      [:opt, :_],
+      [:rest, :_],
+      [:keyreq, :_],
+      [:key, :_],
+      [:keyrest, :_],
+      [:block, :_]
+    ]
+  end
+
+  it "returns :nokey for **nil parameter" do
+    proc { |**nil| }.parameters.should == [[:nokey]]
+  end
+
+  ruby_version_is "3.4"..."4.0" do
+    it "handles the usage of `it` as a parameter" do
+      eval("proc { it }").parameters.should == [[:opt, nil]]
+      eval("lambda { it }").parameters.should == [[:req]]
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "handles the usage of `it` as a parameter" do
+      eval("proc { it }").parameters.should == [[:opt]]
+      eval("lambda { it }").parameters.should == [[:req]]
+    end
+  end
+
+  ruby_version_is "4.1" do
+    it "returns :noblock for &nil parameter" do
+      eval <<~RUBY
+        proc { |&nil| }.parameters.should == [[:noblock]]
+      RUBY
+    end
+  end
 end
diff --git a/spec/ruby/core/proc/ruby2_keywords_spec.rb b/spec/ruby/core/proc/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..e06fad8693
--- /dev/null
+++ b/spec/ruby/core/proc/ruby2_keywords_spec.rb
@@ -0,0 +1,66 @@
+require_relative '../../spec_helper'
+
+describe "Proc#ruby2_keywords" do
+  it "marks the final hash argument as keyword hash" do
+    f = -> *a { a.last }
+    f.ruby2_keywords
+
+    last = f.call(1, 2, a: "a")
+    Hash.ruby2_keywords_hash?(last).should == true
+  end
+
+  it "applies to the underlying method and applies across duplication" do
+    f1 = -> *a { a.last }
+    f1.ruby2_keywords
+    f2 = f1.dup
+
+    Hash.ruby2_keywords_hash?(f1.call(1, 2, a: "a")).should == true
+    Hash.ruby2_keywords_hash?(f2.call(1, 2, a: "a")).should == true
+
+    f3 = -> *a { a.last }
+    f4 = f3.dup
+    f3.ruby2_keywords
+
+    Hash.ruby2_keywords_hash?(f3.call(1, 2, a: "a")).should == true
+    Hash.ruby2_keywords_hash?(f4.call(1, 2, a: "a")).should == true
+  end
+
+  it "returns self" do
+    f = -> *a { }
+    f.ruby2_keywords.should.equal? f
+  end
+
+  it "prints warning when a proc does not accept argument splat" do
+    f = -> a, b, c { }
+
+    -> {
+      f.ruby2_keywords
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  it "prints warning when a proc accepts keywords" do
+    f = -> *a, b: { }
+
+    -> {
+      f.ruby2_keywords
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  it "prints warning when a proc accepts keyword splat" do
+    f = -> *a, **b { }
+
+    -> {
+      f.ruby2_keywords
+    }.should complain(/Skipping set of ruby2_keywords flag for/)
+  end
+
+  ruby_version_is "4.0" do
+    it "prints warning when a proc accepts post arguments" do
+      f = -> *a, b { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain(/Skipping set of ruby2_keywords flag for/)
+    end
+  end
+end
diff --git a/spec/ruby/core/proc/shared/call.rb b/spec/ruby/core/proc/shared/call.rb
index c30ea84b23..fae2331b68 100644
--- a/spec/ruby/core/proc/shared/call.rb
+++ b/spec/ruby/core/proc/shared/call.rb
@@ -49,6 +49,9 @@ describe :proc_call_on_proc_or_lambda, shared: true do
 
     a = proc {|x| x}.send(@method, 1, 2, 3)
     a.should == 1
+
+    a = proc {|x:| x}.send(@method, 2, x: 1)
+    a.should == 1
   end
 
   it "will call #to_ary on argument and return self if return is nil" do
@@ -67,21 +70,21 @@ describe :proc_call_on_proc_or_lambda, shared: true do
   it "raises an ArgumentError on excess arguments when self is a lambda" do
     -> {
       -> x { x }.send(@method, 1, 2)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       -> x { x }.send(@method, 1, 2, 3)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError on missing arguments when self is a lambda" do
     -> {
       -> x { x }.send(@method)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     -> {
       -> x, y { [x,y] }.send(@method, 1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "treats a single Array argument as a single argument when self is a lambda" do
diff --git a/spec/ruby/core/proc/shared/call_arguments.rb b/spec/ruby/core/proc/shared/call_arguments.rb
index ef6ec04620..91ada3439e 100644
--- a/spec/ruby/core/proc/shared/call_arguments.rb
+++ b/spec/ruby/core/proc/shared/call_arguments.rb
@@ -1,7 +1,7 @@
 describe :proc_call_block_args, shared: true do
   it "can receive block arguments" do
     Proc.new {|&b| b.send(@method)}.send(@method) {1 + 1}.should == 2
-    ->&b { b.send(@method)}.send(@method) {1 + 1}.should == 2
+    -> &b { b.send(@method)}.send(@method) {1 + 1}.should == 2
     proc {|&b| b.send(@method)}.send(@method) {1 + 1}.should == 2
   end
 
diff --git a/spec/ruby/core/proc/shared/compose.rb b/spec/ruby/core/proc/shared/compose.rb
index 64338cada8..c004cec7c9 100644
--- a/spec/ruby/core/proc/shared/compose.rb
+++ b/spec/ruby/core/proc/shared/compose.rb
@@ -1,47 +1,22 @@
 describe :proc_compose, shared: true do
-  ruby_version_is "2.6"..."2.7" do
-    it "raises NoMethodError when called if passed not callable object" do
-      not_callable = Object.new
-      composed = @object.call.send(@method, not_callable)
+  it "raises TypeError if passed not callable object" do
+    lhs = @object.call
+    not_callable = Object.new
 
-      -> {
-        composed.call('a')
-      }.should raise_error(NoMethodError, /undefined method `call' for/)
+    -> {
+      lhs.send(@method, not_callable)
+    }.should.raise(TypeError, "callable object is expected")
 
-    end
-
-    it "when called does not try to coerce argument with #to_proc" do
-      succ = Object.new
-      def succ.to_proc(s); s.succ; end
-
-      composed = @object.call.send(@method, succ)
-
-      -> {
-        composed.call('a')
-      }.should raise_error(NoMethodError, /undefined method `call' for/)
-    end
   end
 
-  ruby_version_is "2.7" do # https://bugs.ruby-lang.org/issues/15428
-    it "raises TypeError if passed not callable object" do
-      lhs = @object.call
-      not_callable = Object.new
-
-      -> {
-        lhs.send(@method, not_callable)
-      }.should raise_error(TypeError, "callable object is expected")
-
-    end
-
-    it "does not try to coerce argument with #to_proc" do
-      lhs = @object.call
+  it "does not try to coerce argument with #to_proc" do
+    lhs = @object.call
 
-      succ = Object.new
-      def succ.to_proc(s); s.succ; end
+    succ = Object.new
+    def succ.to_proc(s); s.succ; end
 
-      -> {
-        lhs.send(@method, succ)
-      }.should raise_error(TypeError, "callable object is expected")
-    end
+    -> {
+      lhs.send(@method, succ)
+    }.should.raise(TypeError, "callable object is expected")
   end
 end
diff --git a/spec/ruby/core/proc/shared/dup.rb b/spec/ruby/core/proc/shared/dup.rb
index eda1d6929d..2821d2e00f 100644
--- a/spec/ruby/core/proc/shared/dup.rb
+++ b/spec/ruby/core/proc/shared/dup.rb
@@ -3,8 +3,37 @@ describe :proc_dup, shared: true do
     a = -> { "hello" }
     b = a.send(@method)
 
-    a.should_not equal(b)
+    a.should_not.equal?(b)
 
     a.call.should == b.call
   end
+
+  it "returns an instance of subclass" do
+    cl = Class.new(Proc)
+
+    cl.new{}.send(@method).class.should == cl
+  end
+
+  ruby_version_is "3.4" do
+    it "copies instance variables" do
+      proc = -> { "hello" }
+      proc.instance_variable_set(:@ivar, 1)
+      cl = proc.send(@method)
+      cl.instance_variables.should == [:@ivar]
+    end
+
+    it "copies the finalizer" do
+      code = <<-'RUBY'
+        obj = Proc.new { }
+
+        ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized\n" })
+
+        obj.clone
+
+        exit 0
+      RUBY
+
+      ruby_exe(code).lines.sort.should == ["finalized\n", "finalized\n"]
+    end
+  end
 end
diff --git a/spec/ruby/core/proc/shared/equal.rb b/spec/ruby/core/proc/shared/equal.rb
index 46a1894424..4f6f6c41be 100644
--- a/spec/ruby/core/proc/shared/equal.rb
+++ b/spec/ruby/core/proc/shared/equal.rb
@@ -3,29 +3,29 @@ require_relative '../fixtures/common'
 
 describe :proc_equal, shared: true do
   it "is a public method" do
-    Proc.should have_public_instance_method(@method, false)
+    Proc.public_instance_methods(false).should.include?(@method)
   end
 
   it "returns true if self and other are the same object" do
     p = proc { :foo }
-    p.send(@method, p).should be_true
+    p.send(@method, p).should == true
 
     p = Proc.new { :foo }
-    p.send(@method, p).should be_true
+    p.send(@method, p).should == true
 
     p = -> { :foo }
-    p.send(@method, p).should be_true
+    p.send(@method, p).should == true
   end
 
   it "returns true if other is a dup of the original" do
     p = proc { :foo }
-    p.send(@method, p.dup).should be_true
+    p.send(@method, p.dup).should == true
 
     p = Proc.new { :foo }
-    p.send(@method, p.dup).should be_true
+    p.send(@method, p.dup).should == true
 
     p = -> { :foo }
-    p.send(@method, p.dup).should be_true
+    p.send(@method, p.dup).should == true
   end
 
   # identical here means the same method invocation.
@@ -33,68 +33,51 @@ describe :proc_equal, shared: true do
     a = ProcSpecs.proc_for_1
     b = ProcSpecs.proc_for_1
 
-    a.send(@method, b).should be_false
+    a.send(@method, b).should == false
   end
 
-  it "returns true if both procs have the same body and environment" do
+  it "returns false if procs are distinct but have the same body and environment" do
     p = proc { :foo }
     p2 = proc { :foo }
-    p.send(@method, p2).should be_true
+    p.send(@method, p2).should == false
   end
 
-  it "returns true if both lambdas with the same body and environment" do
+  it "returns false if lambdas are distinct but have same body and environment" do
     x = -> { :foo }
     x2 = -> { :foo }
-    x.send(@method, x2).should be_true
+    x.send(@method, x2).should == false
   end
 
-  it "returns true if both different kinds of procs with the same body and env" do
+  it "returns false if using comparing lambda to proc, even with the same body and env" do
     p = -> { :foo }
     p2 = proc { :foo }
-    p.send(@method, p2).should be_true
+    p.send(@method, p2).should == false
 
     x = proc { :bar }
     x2 = -> { :bar }
-    x.send(@method, x2).should be_true
+    x.send(@method, x2).should == false
   end
 
   it "returns false if other is not a Proc" do
     p = proc { :foo }
-    p.send(@method, []).should be_false
+    p.send(@method, []).should == false
 
     p = Proc.new { :foo }
-    p.send(@method, Object.new).should be_false
+    p.send(@method, Object.new).should == false
 
     p = -> { :foo }
-    p.send(@method, :foo).should be_false
+    p.send(@method, :foo).should == false
   end
 
   it "returns false if self and other are both procs but have different bodies" do
     p = proc { :bar }
     p2 = proc { :foo }
-    p.send(@method, p2).should be_false
+    p.send(@method, p2).should == false
   end
 
   it "returns false if self and other are both lambdas but have different bodies" do
     p = -> { :foo }
     p2 = -> { :bar }
-    p.send(@method, p2).should be_false
-  end
-end
-
-describe :proc_equal_undefined, shared: true do
-  it "is not defined" do
-    Proc.should_not have_instance_method(@method, false)
-  end
-
-  it "returns false if other is a dup of the original" do
-    p = proc { :foo }
-    p.send(@method, p.dup).should be_false
-
-    p = Proc.new { :foo }
-    p.send(@method, p.dup).should be_false
-
-    p = -> { :foo }
-    p.send(@method, p.dup).should be_false
+    p.send(@method, p2).should == false
   end
 end
diff --git a/spec/ruby/core/proc/shared/to_s.rb b/spec/ruby/core/proc/shared/to_s.rb
index 8b9c83927f..a52688a89f 100644
--- a/spec/ruby/core/proc/shared/to_s.rb
+++ b/spec/ruby/core/proc/shared/to_s.rb
@@ -1,9 +1,7 @@
 describe :proc_to_s, shared: true do
-  sep = ruby_version_is("2.7") ? " " : "@"
-
   describe "for a proc created with Proc.new" do
     it "returns a description including file and line number" do
-      Proc.new { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?)#{sep}#{Regexp.escape __FILE__}:#{__LINE__ }>$/
+      Proc.new { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?) #{Regexp.escape __FILE__}:#{__LINE__ }>$/
     end
 
     it "has a binary encoding" do
@@ -13,7 +11,7 @@ describe :proc_to_s, shared: true do
 
   describe "for a proc created with lambda" do
     it "returns a description including '(lambda)' and including file and line number" do
-      -> { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?)#{sep}#{Regexp.escape __FILE__}:#{__LINE__ } \(lambda\)>$/
+      -> { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?) #{Regexp.escape __FILE__}:#{__LINE__ } \(lambda\)>$/
     end
 
     it "has a binary encoding" do
@@ -23,7 +21,7 @@ describe :proc_to_s, shared: true do
 
   describe "for a proc created with proc" do
     it "returns a description including file and line number" do
-      proc { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?)#{sep}#{Regexp.escape __FILE__}:#{__LINE__ }>$/
+      proc { "hello" }.send(@method).should =~ /^#<Proc:([^ ]*?) #{Regexp.escape __FILE__}:#{__LINE__ }>$/
     end
 
     it "has a binary encoding" do
@@ -34,7 +32,12 @@ describe :proc_to_s, shared: true do
   describe "for a proc created with UnboundMethod#to_proc" do
     it "returns a description including '(lambda)' and optionally including file and line number" do
       def hello; end
-      method("hello").to_proc.send(@method).should =~ /^#<Proc:([^ ]*?)(#{sep}#{Regexp.escape __FILE__}:#{__LINE__ })? \(lambda\)>$/
+      s = method("hello").to_proc.send(@method)
+      if s.include? __FILE__
+        s.should =~ /^#<Proc:([^ ]*?) #{Regexp.escape __FILE__}:#{__LINE__ - 3} \(lambda\)>$/
+      else
+        s.should =~ /^#<Proc:([^ ]*?) \(lambda\)>$/
+      end
     end
 
     it "has a binary encoding" do
@@ -46,7 +49,7 @@ describe :proc_to_s, shared: true do
   describe "for a proc created with Symbol#to_proc" do
     it "returns a description including '(&:symbol)'" do
       proc = :foobar.to_proc
-      proc.send(@method).should =~ /^#<Proc:0x\h+\(&:foobar\)>$/
+      proc.send(@method).should.include?('(&:foobar)')
     end
 
     it "has a binary encoding" do
diff --git a/spec/ruby/core/proc/source_location_spec.rb b/spec/ruby/core/proc/source_location_spec.rb
index b5b8178df2..d27ad0559e 100644
--- a/spec/ruby/core/proc/source_location_spec.rb
+++ b/spec/ruby/core/proc/source_location_spec.rb
@@ -10,45 +10,45 @@ describe "Proc#source_location" do
   end
 
   it "returns an Array" do
-    @proc.source_location.should be_an_instance_of(Array)
-    @proc_new.source_location.should be_an_instance_of(Array)
-    @lambda.source_location.should be_an_instance_of(Array)
-    @method.source_location.should be_an_instance_of(Array)
+    @proc.source_location.should.instance_of?(Array)
+    @proc_new.source_location.should.instance_of?(Array)
+    @lambda.source_location.should.instance_of?(Array)
+    @method.source_location.should.instance_of?(Array)
   end
 
   it "sets the first value to the path of the file in which the proc was defined" do
     file = @proc.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/source_location.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
     file = @proc_new.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/source_location.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
     file = @lambda.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/source_location.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
     file = @method.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/source_location.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/source_location.rb', __dir__)
   end
 
-  it "sets the last value to a Fixnum representing the line on which the proc was defined" do
+  it "sets the last value to an Integer representing the line on which the proc was defined" do
     line = @proc.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 4
 
     line = @proc_new.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 12
 
     line = @lambda.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 8
 
     line = @method.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 15
   end
 
@@ -83,4 +83,9 @@ describe "Proc#source_location" do
 
     proc.source_location.should == nil
   end
+
+  it "works for eval with a given line" do
+    proc = eval('-> {}', nil, "foo", 100)
+    proc.source_location.should == ["foo", 100]
+  end
 end
diff --git a/spec/ruby/core/proc/to_proc_spec.rb b/spec/ruby/core/proc/to_proc_spec.rb
index ffaa34929b..7f35a4f19b 100644
--- a/spec/ruby/core/proc/to_proc_spec.rb
+++ b/spec/ruby/core/proc/to_proc_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Proc#to_proc" do
   it "returns self" do
     [Proc.new {}, -> {}, proc {}].each { |p|
-      p.to_proc.should equal(p)
+      p.to_proc.should.equal?(p)
     }
   end
 end
diff --git a/spec/ruby/core/process/_fork_spec.rb b/spec/ruby/core/process/_fork_spec.rb
new file mode 100644
index 0000000000..620f243ce5
--- /dev/null
+++ b/spec/ruby/core/process/_fork_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+describe "Process._fork" do
+  it "for #respond_to? returns the same as Process.respond_to?(:fork)" do
+    Process.respond_to?(:_fork).should == Process.respond_to?(:fork)
+  end
+
+  # Using respond_to? in a guard here is OK because the correct semantics
+  # are that _fork is implemented if and only if fork is (see above).
+  guard_not -> { Process.respond_to?(:fork) } do
+    it "raises a NotImplementedError when called" do
+      -> { Process._fork }.should.raise(NotImplementedError)
+    end
+  end
+
+  guard -> { Process.respond_to?(:fork) } do
+    it "is called by Process#fork" do
+      Process.should_receive(:_fork).once.and_return(42)
+
+      pid = Process.fork {}
+      pid.should.equal?(42)
+    end
+  end
+end
diff --git a/spec/ruby/core/process/argv0_spec.rb b/spec/ruby/core/process/argv0_spec.rb
new file mode 100644
index 0000000000..4c7a2c9ecb
--- /dev/null
+++ b/spec/ruby/core/process/argv0_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../spec_helper'
+
+describe "Process.argv0" do
+  it "returns a String" do
+    Process.argv0.should.is_a?(String)
+  end
+
+  it "is the path given as the main script and the same as __FILE__" do
+    script = "fixtures/argv0.rb"
+
+    Dir.chdir(__dir__) do
+      ruby_exe(script).should == "#{script}\n#{script}\nOK"
+    end
+  end
+
+  it "returns a frozen object" do
+    Process.argv0.should.frozen?
+  end
+
+  it "returns every time the same object" do
+    Process.argv0.should.equal?(Process.argv0)
+  end
+end
diff --git a/spec/ruby/core/process/clock_getres_spec.rb b/spec/ruby/core/process/clock_getres_spec.rb
index 7112b0520a..85aa2b25f1 100644
--- a/spec/ruby/core/process/clock_getres_spec.rb
+++ b/spec/ruby/core/process/clock_getres_spec.rb
@@ -1,37 +1,6 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/clocks'
 
 describe "Process.clock_getres" do
-  # clock_getres() seems completely buggy on FreeBSD:
-  # https://rubyci.org/logs/rubyci.s3.amazonaws.com/freebsd11zfs/ruby-trunk/log/20190428T093003Z.fail.html.gz
-  platform_is_not :freebsd, :openbsd do
-    # NOTE: Look at fixtures/clocks.rb for clock and OS-specific exclusions
-    ProcessSpecs.clock_constants_for_resolution_checks.each do |name, value|
-      it "matches the clock in practice for Process::#{name}" do
-        times = []
-        10_000.times do
-          times << Process.clock_gettime(value, :nanosecond)
-        end
-        reported = Process.clock_getres(value, :nanosecond)
-
-        # The clock should not be more accurate than reported (times should be
-        # a multiple of reported precision.)
-        times.select { |t| t % reported > 0 }.should be_empty
-
-        # We're assuming precision is a multiple of ten - it may or may not
-        # be an incompatibility if it isn't but we'd like to notice this,
-        # and the spec following these wouldn't work if it isn't.
-        reported.should > 0
-        (reported == 1 || reported % 10 == 0).should be_true
-
-        # The clock should not be less accurate than reported (times should
-        # not all be a multiple of the next precision up, assuming precisions
-        # are multiples of ten.)
-        times.select { |t| t % (reported * 10) == 0 }.size.should_not == times.size
-      end
-    end
-  end
-
   # These are documented
 
   it "with :GETTIMEOFDAY_BASED_CLOCK_REALTIME reports 1 microsecond" do
@@ -50,15 +19,15 @@ describe "Process.clock_getres" do
 
   # These are observed
 
-  platform_is_not :solaris, :aix, :openbsd do
-    it "with Process::CLOCK_REALTIME reports at least 1 microsecond" do
-      Process.clock_getres(Process::CLOCK_REALTIME, :nanosecond).should <= 1_000
+  platform_is :linux, :darwin, :windows do
+    it "with Process::CLOCK_REALTIME reports at least 10 millisecond" do
+      Process.clock_getres(Process::CLOCK_REALTIME, :nanosecond).should <= 10_000_000
     end
   end
 
-  platform_is_not :aix, :openbsd do
-    it "with Process::CLOCK_MONOTONIC reports at least 1 microsecond" do
-      Process.clock_getres(Process::CLOCK_MONOTONIC, :nanosecond).should <= 1_000
+  platform_is :linux, :darwin, :windows do
+    it "with Process::CLOCK_MONOTONIC reports at least 10 millisecond" do
+      Process.clock_getres(Process::CLOCK_MONOTONIC, :nanosecond).should <= 10_000_000
     end
   end
 end
diff --git a/spec/ruby/core/process/clock_gettime_spec.rb b/spec/ruby/core/process/clock_gettime_spec.rb
index d3f973d7ae..88158904e1 100644
--- a/spec/ruby/core/process/clock_gettime_spec.rb
+++ b/spec/ruby/core/process/clock_gettime_spec.rb
@@ -4,31 +4,31 @@ require_relative 'fixtures/clocks'
 describe "Process.clock_gettime" do
   ProcessSpecs.clock_constants.each do |name, value|
     it "can be called with Process::#{name}" do
-      Process.clock_gettime(value).should be_an_instance_of(Float)
+      Process.clock_gettime(value).should.instance_of?(Float)
     end
   end
 
   describe 'time units' do
     it 'handles a fixed set of time units' do
       [:nanosecond, :microsecond, :millisecond, :second].each do |unit|
-        Process.clock_gettime(Process::CLOCK_MONOTONIC, unit).should be_kind_of(Integer)
+        Process.clock_gettime(Process::CLOCK_MONOTONIC, unit).should.is_a?(Integer)
       end
 
       [:float_microsecond, :float_millisecond, :float_second].each do |unit|
-        Process.clock_gettime(Process::CLOCK_MONOTONIC, unit).should be_an_instance_of(Float)
+        Process.clock_gettime(Process::CLOCK_MONOTONIC, unit).should.instance_of?(Float)
       end
     end
 
     it 'raises an ArgumentError for an invalid time unit' do
-      -> { Process.clock_gettime(Process::CLOCK_MONOTONIC, :bad) }.should raise_error(ArgumentError)
+      -> { Process.clock_gettime(Process::CLOCK_MONOTONIC, :bad) }.should.raise(ArgumentError)
     end
 
     it 'defaults to :float_second' do
       t1 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
       t2 = Process.clock_gettime(Process::CLOCK_MONOTONIC, :float_second)
 
-      t1.should be_an_instance_of(Float)
-      t2.should be_an_instance_of(Float)
+      t1.should.instance_of?(Float)
+      t2.should.instance_of?(Float)
       t2.should be_close(t1, TIME_TOLERANCE)
     end
 
@@ -36,9 +36,117 @@ describe "Process.clock_gettime" do
       t1 = Process.clock_gettime(Process::CLOCK_MONOTONIC, nil)
       t2 = Process.clock_gettime(Process::CLOCK_MONOTONIC, :float_second)
 
-      t1.should be_an_instance_of(Float)
-      t2.should be_an_instance_of(Float)
+      t1.should.instance_of?(Float)
+      t2.should.instance_of?(Float)
       t2.should be_close(t1, TIME_TOLERANCE)
     end
   end
+
+  describe "supports the platform clocks mentioned in the documentation" do
+    it "CLOCK_REALTIME" do
+      Process.clock_gettime(Process::CLOCK_REALTIME).should.instance_of?(Float)
+    end
+
+    it "CLOCK_MONOTONIC" do
+      Process.clock_gettime(Process::CLOCK_MONOTONIC).should.instance_of?(Float)
+    end
+
+    # These specs need macOS 10.12+ / darwin 16+
+    guard -> { platform_is_not(:darwin) or kernel_version_is '16' } do
+      platform_is :linux, :openbsd, :darwin do
+        it "CLOCK_PROCESS_CPUTIME_ID" do
+          Process.clock_gettime(Process::CLOCK_PROCESS_CPUTIME_ID).should.instance_of?(Float)
+        end
+      end
+
+      platform_is :linux, :freebsd, :openbsd, :darwin do
+        it "CLOCK_THREAD_CPUTIME_ID" do
+          Process.clock_gettime(Process::CLOCK_THREAD_CPUTIME_ID).should.instance_of?(Float)
+        end
+      end
+
+      platform_is :linux, :darwin do
+        it "CLOCK_MONOTONIC_RAW" do
+          Process.clock_gettime(Process::CLOCK_MONOTONIC_RAW).should.instance_of?(Float)
+        end
+      end
+
+      platform_is :darwin do
+        it "CLOCK_MONOTONIC_RAW_APPROX" do
+          Process.clock_gettime(Process::CLOCK_MONOTONIC_RAW_APPROX).should.instance_of?(Float)
+        end
+
+        it "CLOCK_UPTIME_RAW and CLOCK_UPTIME_RAW_APPROX" do
+          Process.clock_gettime(Process::CLOCK_UPTIME_RAW).should.instance_of?(Float)
+          Process.clock_gettime(Process::CLOCK_UPTIME_RAW_APPROX).should.instance_of?(Float)
+        end
+      end
+    end
+
+    platform_is :freebsd do
+      it "CLOCK_VIRTUAL" do
+        Process.clock_gettime(Process::CLOCK_VIRTUAL).should.instance_of?(Float)
+      end
+
+      it "CLOCK_PROF" do
+        Process.clock_gettime(Process::CLOCK_PROF).should.instance_of?(Float)
+      end
+    end
+
+    platform_is :freebsd, :openbsd do
+      it "CLOCK_UPTIME" do
+        Process.clock_gettime(Process::CLOCK_UPTIME).should.instance_of?(Float)
+      end
+    end
+
+    platform_is :freebsd do
+      it "CLOCK_REALTIME_FAST and CLOCK_REALTIME_PRECISE" do
+        Process.clock_gettime(Process::CLOCK_REALTIME_FAST).should.instance_of?(Float)
+        Process.clock_gettime(Process::CLOCK_REALTIME_PRECISE).should.instance_of?(Float)
+      end
+
+      it "CLOCK_MONOTONIC_FAST and CLOCK_MONOTONIC_PRECISE" do
+        Process.clock_gettime(Process::CLOCK_MONOTONIC_FAST).should.instance_of?(Float)
+        Process.clock_gettime(Process::CLOCK_MONOTONIC_PRECISE).should.instance_of?(Float)
+      end
+
+      it "CLOCK_UPTIME_FAST and CLOCK_UPTIME_PRECISE" do
+        Process.clock_gettime(Process::CLOCK_UPTIME_FAST).should.instance_of?(Float)
+        Process.clock_gettime(Process::CLOCK_UPTIME_PRECISE).should.instance_of?(Float)
+      end
+
+      it "CLOCK_SECOND" do
+        Process.clock_gettime(Process::CLOCK_SECOND).should.instance_of?(Float)
+      end
+    end
+
+    guard -> { platform_is :linux and kernel_version_is '2.6.32' } do
+      it "CLOCK_REALTIME_COARSE" do
+        Process.clock_gettime(Process::CLOCK_REALTIME_COARSE).should.instance_of?(Float)
+      end
+
+      it "CLOCK_MONOTONIC_COARSE" do
+        Process.clock_gettime(Process::CLOCK_MONOTONIC_COARSE).should.instance_of?(Float)
+      end
+    end
+
+    guard -> { platform_is :linux and kernel_version_is '2.6.39' } do
+      it "CLOCK_BOOTTIME" do
+        skip "No Process::CLOCK_BOOTTIME" unless defined?(Process::CLOCK_BOOTTIME)
+        Process.clock_gettime(Process::CLOCK_BOOTTIME).should.instance_of?(Float)
+      end
+    end
+
+    guard -> { platform_is "x86_64-linux" and kernel_version_is '3.0' } do
+      it "CLOCK_REALTIME_ALARM" do
+        skip "No Process::CLOCK_REALTIME_ALARM" unless defined?(Process::CLOCK_REALTIME_ALARM)
+        Process.clock_gettime(Process::CLOCK_REALTIME_ALARM).should.instance_of?(Float)
+      end
+
+      it "CLOCK_BOOTTIME_ALARM" do
+        skip "No Process::CLOCK_BOOTTIME_ALARM" unless defined?(Process::CLOCK_BOOTTIME_ALARM)
+        Process.clock_gettime(Process::CLOCK_BOOTTIME_ALARM).should.instance_of?(Float)
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/process/constants_spec.rb b/spec/ruby/core/process/constants_spec.rb
index 2fa93ad8bf..5a4c478e74 100644
--- a/spec/ruby/core/process/constants_spec.rb
+++ b/spec/ruby/core/process/constants_spec.rb
@@ -1,63 +1,126 @@
+require_relative '../../spec_helper'
 
 describe "Process::Constants" do
   platform_is :darwin, :netbsd, :freebsd do
-    it "has the correct constant values on BSD-like systems" do
-      Process::WNOHANG.should == 1
-      Process::WUNTRACED.should == 2
-      Process::PRIO_PROCESS.should == 0
-      Process::PRIO_PGRP.should == 1
-      Process::PRIO_USER.should == 2
-      Process::RLIM_INFINITY.should == 9223372036854775807
-      Process::RLIMIT_CPU.should == 0
-      Process::RLIMIT_FSIZE.should == 1
-      Process::RLIMIT_DATA.should == 2
-      Process::RLIMIT_STACK.should == 3
-      Process::RLIMIT_CORE.should == 4
-      Process::RLIMIT_RSS.should == 5
-      Process::RLIMIT_MEMLOCK.should == 6
-      Process::RLIMIT_NPROC.should == 7
-      Process::RLIMIT_NOFILE.should == 8
+    describe "on BSD-like systems" do
+      %i[
+          WNOHANG
+          WUNTRACED
+          PRIO_PROCESS
+          PRIO_PGRP
+          PRIO_USER
+          RLIM_INFINITY
+          RLIMIT_CPU
+          RLIMIT_FSIZE
+          RLIMIT_DATA
+          RLIMIT_STACK
+          RLIMIT_CORE
+          RLIMIT_RSS
+          RLIMIT_MEMLOCK
+          RLIMIT_NPROC
+          RLIMIT_NOFILE
+      ].each do |const|
+        it "defines #{const}" do
+          Process.const_defined?(const).should == true
+          Process.const_get(const).should.instance_of?(Integer)
+        end
+      end
     end
   end
 
   platform_is :darwin do
-    it "has the correct constant values on Darwin" do
-      Process::RLIM_SAVED_MAX.should == 9223372036854775807
-      Process::RLIM_SAVED_CUR.should == 9223372036854775807
-      Process::RLIMIT_AS.should == 5
+    describe "on Darwin" do
+      %i[
+        RLIM_SAVED_MAX
+        RLIM_SAVED_CUR
+        RLIMIT_AS
+      ].each do |const|
+        it "defines #{const}" do
+          Process.const_defined?(const).should == true
+          Process.const_get(const).should.instance_of?(Integer)
+        end
+      end
     end
   end
 
   platform_is :linux do
-    it "has the correct constant values on Linux" do
-      Process::WNOHANG.should == 1
-      Process::WUNTRACED.should == 2
-      Process::PRIO_PROCESS.should == 0
-      Process::PRIO_PGRP.should == 1
-      Process::PRIO_USER.should == 2
-      Process::RLIMIT_CPU.should == 0
-      Process::RLIMIT_FSIZE.should == 1
-      Process::RLIMIT_DATA.should == 2
-      Process::RLIMIT_STACK.should == 3
-      Process::RLIMIT_CORE.should == 4
-      Process::RLIMIT_RSS.should == 5
-      Process::RLIMIT_NPROC.should == 6
-      Process::RLIMIT_NOFILE.should == 7
-      Process::RLIMIT_MEMLOCK.should == 8
-      Process::RLIMIT_AS.should == 9
-
-      # These values appear to change according to the platform.
-      values = [4294967295, 9223372036854775807, 18446744073709551615]
-      values.include?(Process::RLIM_INFINITY).should be_true
-      values.include?(Process::RLIM_SAVED_MAX).should be_true
-      values.include?(Process::RLIM_SAVED_CUR).should be_true
+    describe "on Linux" do
+      %i[
+        WNOHANG
+        WUNTRACED
+        PRIO_PROCESS
+        PRIO_PGRP
+        PRIO_USER
+        RLIMIT_CPU
+        RLIMIT_FSIZE
+        RLIMIT_DATA
+        RLIMIT_STACK
+        RLIMIT_CORE
+        RLIMIT_RSS
+        RLIMIT_NPROC
+        RLIMIT_NOFILE
+        RLIMIT_MEMLOCK
+        RLIMIT_AS
+        RLIM_INFINITY
+        RLIM_SAVED_MAX
+        RLIM_SAVED_CUR
+      ].each do |const|
+        it "defines #{const}" do
+          Process.const_defined?(const).should == true
+          Process.const_get(const).should.instance_of?(Integer)
+        end
+      end
     end
   end
 
   platform_is :netbsd, :freebsd do
-    it "Process::RLIMIT_SBSIZE" do
-      Process::RLIMIT_SBSIZE.should == 9 # FIXME: what's it equal?
-      Process::RLIMIT_AS.should == 10
+    describe "on NetBSD and FreeBSD" do
+      %i[
+        RLIMIT_SBSIZE
+        RLIMIT_AS
+      ].each do |const|
+        it "defines #{const}" do
+          Process.const_defined?(const).should == true
+          Process.const_get(const).should.instance_of?(Integer)
+        end
+      end
+    end
+  end
+
+  platform_is :freebsd do
+    describe "on FreeBSD" do
+      %i[
+        RLIMIT_NPTS
+      ].each do |const|
+        it "defines #{const}" do
+          Process.const_defined?(const).should == true
+          Process.const_get(const).should.instance_of?(Integer)
+        end
+      end
+    end
+  end
+
+  platform_is :windows do
+    describe "on Windows" do
+      %i[
+          RLIMIT_CPU
+          RLIMIT_FSIZE
+          RLIMIT_DATA
+          RLIMIT_STACK
+          RLIMIT_CORE
+          RLIMIT_RSS
+          RLIMIT_NPROC
+          RLIMIT_NOFILE
+          RLIMIT_MEMLOCK
+          RLIMIT_AS
+          RLIM_INFINITY
+          RLIM_SAVED_MAX
+          RLIM_SAVED_CUR
+      ].each do |const|
+        it "does not define #{const}" do
+          Process.const_defined?(const).should == false
+        end
+      end
     end
   end
 end
diff --git a/spec/ruby/core/process/daemon_spec.rb b/spec/ruby/core/process/daemon_spec.rb
index 70ffd1b320..9b7eba1411 100644
--- a/spec/ruby/core/process/daemon_spec.rb
+++ b/spec/ruby/core/process/daemon_spec.rb
@@ -2,6 +2,9 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/common'
 
 platform_is_not :windows do
+  # macOS 15 is not working this examples
+  return if /darwin/ =~ RUBY_PLATFORM && /15/ =~ `sw_vers -productVersion`
+
   describe :process_daemon_keep_stdio_open_false, shared: true do
     it "redirects stdout to /dev/null" do
       @daemon.invoke("keep_stdio_open_false_stdout", @object).should == ""
@@ -109,7 +112,7 @@ platform_is :windows do
     it "raises a NotImplementedError" do
       -> {
         Process.daemon
-      }.should raise_error(NotImplementedError)
+      }.should.raise(NotImplementedError)
     end
   end
 end
diff --git a/spec/ruby/core/process/detach_spec.rb b/spec/ruby/core/process/detach_spec.rb
index 1c27ed9c2c..33c674394e 100644
--- a/spec/ruby/core/process/detach_spec.rb
+++ b/spec/ruby/core/process/detach_spec.rb
@@ -5,7 +5,7 @@ describe "Process.detach" do
     it "returns a thread" do
       pid = Process.fork { Process.exit! }
       thr = Process.detach(pid)
-      thr.should be_kind_of(Thread)
+      thr.should.is_a?(Thread)
       thr.join
     end
 
@@ -15,7 +15,7 @@ describe "Process.detach" do
       thr.join
 
       status = thr.value
-      status.should be_kind_of(Process::Status)
+      status.should.is_a?(Process::Status)
       status.pid.should == pid
     end
 
@@ -23,7 +23,7 @@ describe "Process.detach" do
       it "reaps the child process's status automatically" do
         pid = Process.fork { Process.exit! }
         Process.detach(pid).join
-        -> { Process.waitpid(pid) }.should raise_error(Errno::ECHILD)
+        -> { Process.waitpid(pid) }.should.raise(Errno::ECHILD)
       end
     end
 
@@ -42,5 +42,40 @@ describe "Process.detach" do
 
       thr.pid.should == pid
     end
+
+    it "tolerates not existing child process pid" do
+      # Use a value that is close to the INT_MAX (pid usually is signed int).
+      # It should (at least) be greater than allowed pid limit value that depends on OS.
+      pid_not_existing = 2.pow(30)
+
+      # Check that there is no a child process with this hardcoded pid.
+      # Command `kill 0 pid`:
+      # - returns "1" if a process exists and
+      # - raises Errno::ESRCH otherwise
+      -> {  Process.kill(0, pid_not_existing) }.should.raise(Errno::ESRCH)
+
+      thr = Process.detach(pid_not_existing)
+      thr.join
+
+      thr.should.is_a?(Thread)
+    end
+
+    it "calls #to_int to implicitly convert non-Integer pid to Integer" do
+      pid = MockObject.new('mock-enumerable')
+      pid.should_receive(:to_int).and_return(100500)
+
+      Process.detach(pid).join
+    end
+
+    it "raises TypeError when pid argument does not have #to_int method" do
+      -> { Process.detach(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+
+    it "raises TypeError when #to_int returns non-Integer value" do
+      pid = MockObject.new('mock-enumerable')
+      pid.should_receive(:to_int).and_return(:symbol)
+
+      -> { Process.detach(pid) }.should raise_consistent_error(TypeError, "can't convert MockObject into Integer (MockObject#to_int gives Symbol)")
+    end
   end
 end
diff --git a/spec/ruby/core/process/egid_spec.rb b/spec/ruby/core/process/egid_spec.rb
index 24dda43804..69c86bebe2 100644
--- a/spec/ruby/core/process/egid_spec.rb
+++ b/spec/ruby/core/process/egid_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Process.egid" do
   it "returns the effective group ID for this process" do
-    Process.egid.should be_kind_of(Integer)
+    Process.egid.should.is_a?(Integer)
   end
 
   it "also goes by Process::GID.eid" do
@@ -15,5 +15,44 @@ describe "Process.egid" do
 end
 
 describe "Process.egid=" do
-  it "needs to be reviewed for spec completeness"
+
+  platform_is_not :windows do
+    it "raises TypeError if not passed an Integer or String" do
+      -> { Process.egid = Object.new }.should.raise(TypeError)
+    end
+
+    it "sets the effective group id to its own gid if given the username corresponding to its own gid" do
+      raise unless Process.gid == Process.egid
+
+      require "etc"
+      group = Etc.getgrgid(Process.gid).name
+
+      Process.egid = group
+      Process.egid.should == Process.gid
+    end
+
+    as_user do
+      it "raises Errno::ERPERM if run by a non superuser trying to set the root group id" do
+        -> { Process.egid = 0 }.should.raise(Errno::EPERM)
+      end
+
+      platform_is :linux do
+        it "raises Errno::ERPERM if run by a non superuser trying to set the group id from group name" do
+          -> { Process.egid = "root" }.should.raise(Errno::EPERM)
+        end
+      end
+    end
+
+    as_superuser do
+      context "when ran by a superuser" do
+        it "sets the effective group id for the current process if run by a superuser" do
+          code = <<-RUBY
+            Process.egid = 1
+            puts Process.egid
+          RUBY
+          ruby_exe(code).should == "1\n"
+        end
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/process/euid_spec.rb b/spec/ruby/core/process/euid_spec.rb
index 7bbacfadfd..da76f06e59 100644
--- a/spec/ruby/core/process/euid_spec.rb
+++ b/spec/ruby/core/process/euid_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Process.euid" do
   it "returns the effective user ID for this process" do
-    Process.euid.should be_kind_of(Fixnum)
+    Process.euid.should.is_a?(Integer)
   end
 
   it "also goes by Process::UID.eid" do
@@ -18,16 +18,26 @@ describe "Process.euid=" do
 
   platform_is_not :windows do
     it "raises TypeError if not passed an Integer" do
-      -> { Process.euid = Object.new }.should raise_error(TypeError)
+      -> { Process.euid = Object.new }.should.raise(TypeError)
+    end
+
+    it "sets the effective user id to its own uid if given the username corresponding to its own uid" do
+      raise unless Process.uid == Process.euid
+
+      require "etc"
+      user = Etc.getpwuid(Process.uid).name
+
+      Process.euid = user
+      Process.euid.should == Process.uid
     end
 
     as_user do
       it "raises Errno::ERPERM if run by a non superuser trying to set the superuser id" do
-        -> { (Process.euid = 0)}.should raise_error(Errno::EPERM)
+        -> { Process.euid = 0 }.should.raise(Errno::EPERM)
       end
 
       it "raises Errno::ERPERM if run by a non superuser trying to set the superuser id from username" do
-        -> { Process.euid = "root" }.should raise_error(Errno::EPERM)
+        -> { Process.euid = "root" }.should.raise(Errno::EPERM)
       end
     end
 
diff --git a/spec/ruby/core/process/exec_spec.rb b/spec/ruby/core/process/exec_spec.rb
index 848990c6dc..a48d461b02 100644
--- a/spec/ruby/core/process/exec_spec.rb
+++ b/spec/ruby/core/process/exec_spec.rb
@@ -2,56 +2,48 @@ require_relative '../../spec_helper'
 
 describe "Process.exec" do
   it "raises Errno::ENOENT for an empty string" do
-    -> { Process.exec "" }.should raise_error(Errno::ENOENT)
+    -> { Process.exec "" }.should.raise(Errno::ENOENT)
   end
 
   it "raises Errno::ENOENT for a command which does not exist" do
-    -> { Process.exec "bogus-noent-script.sh" }.should raise_error(Errno::ENOENT)
+    -> { Process.exec "bogus-noent-script.sh" }.should.raise(Errno::ENOENT)
   end
 
   it "raises an ArgumentError if the command includes a null byte" do
-    -> { Process.exec "\000" }.should raise_error(ArgumentError)
+    -> { Process.exec "\000" }.should.raise(ArgumentError)
   end
 
   unless File.executable?(__FILE__) # Some FS (e.g. vboxfs) locate all files executable
     platform_is_not :windows do
       it "raises Errno::EACCES when the file does not have execute permissions" do
-        -> { Process.exec __FILE__ }.should raise_error(Errno::EACCES)
+        -> { Process.exec __FILE__ }.should.raise(Errno::EACCES)
       end
     end
 
     platform_is :windows do
       it "raises Errno::EACCES or Errno::ENOEXEC when the file is not an executable file" do
-        -> { Process.exec __FILE__ }.should raise_error(SystemCallError) { |e|
-          [Errno::EACCES, Errno::ENOEXEC].should include(e.class)
+        -> { Process.exec __FILE__ }.should.raise(SystemCallError) { |e|
+          [Errno::EACCES, Errno::ENOEXEC].should.include?(e.class)
         }
       end
     end
   end
 
-  platform_is_not :openbsd do
-    it "raises Errno::EACCES when passed a directory" do
-      -> { Process.exec File.dirname(__FILE__) }.should raise_error(Errno::EACCES)
-    end
-  end
-
-  platform_is :openbsd do
-    it "raises Errno::EISDIR when passed a directory" do
-      -> { Process.exec File.dirname(__FILE__) }.should raise_error(Errno::EISDIR)
-    end
+  it "raises Errno::EACCES when passed a directory" do
+    -> { Process.exec __dir__ }.should.raise(Errno::EACCES)
   end
 
   it "runs the specified command, replacing current process" do
-    ruby_exe('Process.exec "echo hello"; puts "fail"', escape: true).should == "hello\n"
+    ruby_exe('Process.exec "echo hello"; puts "fail"').should == "hello\n"
   end
 
   it "sets the current directory when given the :chdir option" do
     tmpdir = tmp("")[0..-2]
     platform_is_not :windows do
-      ruby_exe("Process.exec(\"pwd\", chdir: #{tmpdir.inspect})", escape: true).should == "#{tmpdir}\n"
+      ruby_exe("Process.exec(\"pwd\", chdir: #{tmpdir.inspect})").should == "#{tmpdir}\n"
     end
     platform_is :windows do
-      ruby_exe("Process.exec(\"cd\", chdir: #{tmpdir.inspect})", escape: true).tr('\\', '/').should == "#{tmpdir}\n"
+      ruby_exe("Process.exec(\"cd\", chdir: #{tmpdir.inspect})").tr('\\', '/').should == "#{tmpdir}\n"
     end
   end
 
@@ -81,13 +73,13 @@ describe "Process.exec" do
     platform_is_not :windows do
       it "subjects the specified command to shell expansion" do
         result = Dir.chdir(@dir) do
-          ruby_exe('Process.exec "echo *"', escape: true)
+          ruby_exe('Process.exec "echo *"')
         end
         result.chomp.should == @name
       end
 
       it "creates an argument array with shell parsing semantics for whitespace" do
-        ruby_exe('Process.exec "echo a b  c   d"', escape: true).should == "a b c d\n"
+        ruby_exe('Process.exec "echo a b  c   d"').should == "a b c d\n"
       end
     end
 
@@ -95,13 +87,13 @@ describe "Process.exec" do
       # There is no shell expansion on Windows
       it "does not subject the specified command to shell expansion on Windows" do
         result = Dir.chdir(@dir) do
-          ruby_exe('Process.exec "echo *"', escape: true)
+          ruby_exe('Process.exec "echo *"')
         end
         result.should == "*\n"
       end
 
       it "does not create an argument array with shell parsing semantics for whitespace on Windows" do
-        ruby_exe('Process.exec "echo a b  c   d"', escape: true).should == "a b  c   d\n"
+        ruby_exe('Process.exec "echo a b  c   d"').should == "a b  c   d\n"
       end
     end
 
@@ -113,7 +105,7 @@ describe "Process.exec" do
       platform_is :windows do
         cmd = '"cmd.exe", "/C", "echo", "*"'
       end
-      ruby_exe("Process.exec #{cmd}", escape: true).should == "*\n"
+      ruby_exe("Process.exec #{cmd}").should == "*\n"
     end
   end
 
@@ -132,29 +124,29 @@ describe "Process.exec" do
     end
 
     it "sets environment variables in the child environment" do
-      ruby_exe('Process.exec({"FOO" => "BAR"}, "echo ' + var + '")', escape: true).should == "BAR\n"
+      ruby_exe('Process.exec({"FOO" => "BAR"}, "echo ' + var + '")').should == "BAR\n"
     end
 
     it "unsets environment variables whose value is nil" do
       platform_is_not :windows do
-        ruby_exe('Process.exec({"FOO" => nil}, "echo ' + var + '")', escape: true).should == "\n"
+        ruby_exe('Process.exec({"FOO" => nil}, "echo ' + var + '")').should == "\n"
       end
       platform_is :windows do
         # On Windows, echo-ing a non-existent env var is treated as echo-ing any other string of text
-        ruby_exe('Process.exec({"FOO" => nil}, "echo ' + var + '")', escape: true).should == var + "\n"
+        ruby_exe('Process.exec({"FOO" => nil}, "echo ' + var + '")').should == var + "\n"
       end
     end
 
     it "coerces environment argument using to_hash" do
-      ruby_exe('o = Object.new; def o.to_hash; {"FOO" => "BAR"}; end; Process.exec(o, "echo ' + var + '")', escape: true).should == "BAR\n"
+      ruby_exe('o = Object.new; def o.to_hash; {"FOO" => "BAR"}; end; Process.exec(o, "echo ' + var + '")').should == "BAR\n"
     end
 
     it "unsets other environment variables when given a true :unsetenv_others option" do
       platform_is_not :windows do
-        ruby_exe('Process.exec("echo ' + var + '", unsetenv_others: true)', escape: true).should == "\n"
+        ruby_exe('Process.exec("echo ' + var + '", unsetenv_others: true)').should == "\n"
       end
       platform_is :windows do
-        ruby_exe('Process.exec("' + ENV['COMSPEC'].gsub('\\', '\\\\\\') + ' /C echo ' + var + '", unsetenv_others: true)', escape: true).should == var + "\n"
+        ruby_exe('Process.exec("' + ENV['COMSPEC'].gsub('\\', '\\\\\\') + ' /C echo ' + var + '", unsetenv_others: true)').should == var + "\n"
       end
     end
   end
@@ -162,26 +154,26 @@ describe "Process.exec" do
   describe "with a command array" do
     it "uses the first element as the command name and the second as the argv[0] value" do
       platform_is_not :windows do
-        ruby_exe('Process.exec(["/bin/sh", "argv_zero"], "-c", "echo $0")', escape: true).should == "argv_zero\n"
+        ruby_exe('Process.exec(["/bin/sh", "argv_zero"], "-c", "echo $0")').should == "argv_zero\n"
       end
       platform_is :windows do
-        ruby_exe('Process.exec(["cmd.exe", "/C"], "/C", "echo", "argv_zero")', escape: true).should == "argv_zero\n"
+        ruby_exe('Process.exec(["cmd.exe", "/C"], "/C", "echo", "argv_zero")').should == "argv_zero\n"
       end
     end
 
     it "coerces the argument using to_ary" do
       platform_is_not :windows do
-        ruby_exe('o = Object.new; def o.to_ary; ["/bin/sh", "argv_zero"]; end; Process.exec(o, "-c", "echo $0")', escape: true).should == "argv_zero\n"
+        ruby_exe('o = Object.new; def o.to_ary; ["/bin/sh", "argv_zero"]; end; Process.exec(o, "-c", "echo $0")').should == "argv_zero\n"
       end
       platform_is :windows do
-        ruby_exe('o = Object.new; def o.to_ary; ["cmd.exe", "/C"]; end; Process.exec(o, "/C", "echo", "argv_zero")', escape: true).should == "argv_zero\n"
+        ruby_exe('o = Object.new; def o.to_ary; ["cmd.exe", "/C"]; end; Process.exec(o, "/C", "echo", "argv_zero")').should == "argv_zero\n"
       end
     end
 
     it "raises an ArgumentError if the Array does not have exactly two elements" do
-      -> { Process.exec([]) }.should raise_error(ArgumentError)
-      -> { Process.exec([:a]) }.should raise_error(ArgumentError)
-      -> { Process.exec([:a, :b, :c]) }.should raise_error(ArgumentError)
+      -> { Process.exec([]) }.should.raise(ArgumentError)
+      -> { Process.exec([:a]) }.should.raise(ArgumentError)
+      -> { Process.exec([:a, :b, :c]) }.should.raise(ArgumentError)
     end
   end
 
@@ -200,18 +192,49 @@ describe "Process.exec" do
         it "maps the key to a file descriptor in the child that inherits the file descriptor from the parent specified by the value" do
           map_fd_fixture = fixture __FILE__, "map_fd.rb"
           cmd = <<-EOC
-            f = File.open("#{@name}", "w+")
-            child_fd = f.fileno + 1
-            File.open("#{@child_fd_file}", "w") { |io| io.print child_fd }
-            Process.exec "#{ruby_cmd(map_fd_fixture)} \#{child_fd}", { child_fd => f }
+            f = File.open(#{@name.inspect}, "w+")
+            File.open(#{__FILE__.inspect}, "r") do |io|
+              child_fd = io.fileno
+              File.open(#{@child_fd_file.inspect}, "w") { |io| io.print child_fd }
+              Process.exec "#{ruby_cmd(map_fd_fixture)} \#{child_fd}", { child_fd => f }
+            end
             EOC
 
-          ruby_exe(cmd, escape: true)
+          ruby_exe(cmd)
           child_fd = IO.read(@child_fd_file).to_i
           child_fd.to_i.should > STDERR.fileno
 
           File.read(@name).should == "writing to fd: #{child_fd}"
         end
+
+        it "lets the process after exec have specified file descriptor despite close_on_exec" do
+          map_fd_fixture = fixture __FILE__, "map_fd.rb"
+          cmd = <<-EOC
+            f = File.open(#{@name.inspect}, 'w+')
+            puts(f.fileno, f.close_on_exec?)
+            STDOUT.flush
+            Process.exec("#{ruby_cmd(map_fd_fixture)} \#{f.fileno}", f.fileno => f.fileno)
+            EOC
+
+          output = ruby_exe(cmd)
+          child_fd, close_on_exec = output.split
+
+          child_fd.to_i.should > STDERR.fileno
+          close_on_exec.should == 'true'
+          File.read(@name).should == "writing to fd: #{child_fd}"
+        end
+
+        it "sets close_on_exec to false on specified fd even when it fails" do
+          cmd = <<-EOC
+            f = File.open(#{__FILE__.inspect}, 'r')
+            puts(f.close_on_exec?)
+            Process.exec('/', f.fileno => f.fileno) rescue nil
+            puts(f.close_on_exec?)
+            EOC
+
+          output = ruby_exe(cmd)
+          output.split.should == ['true', 'false']
+        end
       end
     end
   end
diff --git a/spec/ruby/core/process/exit_spec.rb b/spec/ruby/core/process/exit_spec.rb
index 70d79d789d..4f7dc94407 100644
--- a/spec/ruby/core/process/exit_spec.rb
+++ b/spec/ruby/core/process/exit_spec.rb
@@ -6,5 +6,5 @@ describe "Process.exit" do
 end
 
 describe "Process.exit!" do
-  it_behaves_like :process_exit!, :exit!, Process
+  it_behaves_like :process_exit!, :exit!, "Process"
 end
diff --git a/spec/ruby/core/process/fixtures/argv0.rb b/spec/ruby/core/process/fixtures/argv0.rb
new file mode 100644
index 0000000000..847a3e903e
--- /dev/null
+++ b/spec/ruby/core/process/fixtures/argv0.rb
@@ -0,0 +1,6 @@
+puts Process.argv0
+puts __FILE__
+
+if Process.argv0 == __FILE__
+  print "OK"
+end
diff --git a/spec/ruby/core/process/fixtures/clocks.rb b/spec/ruby/core/process/fixtures/clocks.rb
index 92540ddd45..5757e280be 100644
--- a/spec/ruby/core/process/fixtures/clocks.rb
+++ b/spec/ruby/core/process/fixtures/clocks.rb
@@ -2,7 +2,7 @@ module ProcessSpecs
   def self.clock_constants
     clocks = []
 
-    platform_is_not :windows, :solaris do
+    platform_is_not :windows do
       clocks += Process.constants.select { |c| c.to_s.start_with?('CLOCK_') }
 
       # These require CAP_WAKE_ALARM and are not documented in
@@ -15,46 +15,4 @@ module ProcessSpecs
       [c, Process.const_get(c)]
     }
   end
-
-  def self.clock_constants_for_resolution_checks
-    clocks = clock_constants
-
-    # These clocks in practice on Linux do not seem to match their reported resolution.
-    platform_is :linux do
-      clocks = clocks.reject { |clock, value|
-        [:CLOCK_REALTIME_COARSE, :CLOCK_MONOTONIC_COARSE].include?(clock)
-      }
-    end
-
-    # These clocks in practice on macOS seem to be less precise than advertised by clock_getres
-    platform_is :darwin do
-      clocks = clocks.reject { |clock, value|
-        [:CLOCK_UPTIME_RAW_APPROX, :CLOCK_MONOTONIC_RAW_APPROX].include?(clock)
-      }
-    end
-
-    # These clocks in practice on ARM on Linux do not seem to match their reported resolution.
-    platform_is :armv7, :aarch64 do
-      clocks = clocks.reject { |clock, value|
-        [:CLOCK_PROCESS_CPUTIME_ID, :CLOCK_THREAD_CPUTIME_ID, :CLOCK_MONOTONIC_RAW].include?(clock)
-      }
-    end
-
-    # These clocks in practice on AIX seem to be more precise than their reported resolution.
-    platform_is :aix do
-      clocks = clocks.reject { |clock, value|
-        [:CLOCK_REALTIME, :CLOCK_MONOTONIC].include?(clock)
-      }
-    end
-
-    # On a Hyper-V Linux guest machine, these clocks in practice
-    # seem to be less precise than advertised by clock_getres
-    platform_is :linux do
-      clocks = clocks.reject { |clock, value|
-        clock == :CLOCK_MONOTONIC_RAW
-      }
-    end
-
-    clocks
-  end
 end
diff --git a/spec/ruby/core/process/fixtures/common.rb b/spec/ruby/core/process/fixtures/common.rb
index bdbf1e654b..f49513d262 100644
--- a/spec/ruby/core/process/fixtures/common.rb
+++ b/spec/ruby/core/process/fixtures/common.rb
@@ -3,11 +3,15 @@ module ProcessSpecs
     if defined?(MSpecScript::SYSTEM_RUBY)
       context.send(:before, :all) do
         @ruby = ::RUBY_EXE
-        Object.const_set(:RUBY_EXE, MSpecScript::SYSTEM_RUBY)
+        suppress_warning {
+          Object.const_set(:RUBY_EXE, MSpecScript::SYSTEM_RUBY)
+        }
       end
 
       context.send(:after, :all) do
-        Object.const_set(:RUBY_EXE, @ruby)
+        suppress_warning {
+          Object.const_set(:RUBY_EXE, @ruby)
+        }
       end
     end
   end
diff --git a/spec/ruby/core/process/fixtures/kill.rb b/spec/ruby/core/process/fixtures/kill.rb
index 0b88f8ee1f..b922a043f1 100644
--- a/spec/ruby/core/process/fixtures/kill.rb
+++ b/spec/ruby/core/process/fixtures/kill.rb
@@ -1,5 +1,3 @@
-require 'thread'
-
 pid_file = ARGV.shift
 scenario = ARGV.shift
 
diff --git a/spec/ruby/core/process/getpriority_spec.rb b/spec/ruby/core/process/getpriority_spec.rb
index 4b66e18679..53fe7bfe20 100644
--- a/spec/ruby/core/process/getpriority_spec.rb
+++ b/spec/ruby/core/process/getpriority_spec.rb
@@ -5,19 +5,19 @@ describe "Process.getpriority" do
 
     it "coerces arguments to Integers" do
       ret = Process.getpriority mock_int(Process::PRIO_PROCESS), mock_int(0)
-      ret.should be_kind_of(Fixnum)
+      ret.should.is_a?(Integer)
     end
 
     it "gets the scheduling priority for a specified process" do
-      Process.getpriority(Process::PRIO_PROCESS, 0).should be_kind_of(Fixnum)
+      Process.getpriority(Process::PRIO_PROCESS, 0).should.is_a?(Integer)
     end
 
     it "gets the scheduling priority for a specified process group" do
-      Process.getpriority(Process::PRIO_PGRP, 0).should be_kind_of(Fixnum)
+      Process.getpriority(Process::PRIO_PGRP, 0).should.is_a?(Integer)
     end
 
     it "gets the scheduling priority for a specified user" do
-      Process.getpriority(Process::PRIO_USER, 0).should be_kind_of(Fixnum)
+      Process.getpriority(Process::PRIO_USER, 0).should.is_a?(Integer)
     end
   end
 end
diff --git a/spec/ruby/core/process/getrlimit_spec.rb b/spec/ruby/core/process/getrlimit_spec.rb
index f77a61a475..d36d8c3335 100644
--- a/spec/ruby/core/process/getrlimit_spec.rb
+++ b/spec/ruby/core/process/getrlimit_spec.rb
@@ -11,13 +11,13 @@ platform_is :aix do
   Process.getrlimit(:DATA)
 end
 
-platform_is_not :windows do
-  describe "Process.getrlimit" do
+describe "Process.getrlimit" do
+  platform_is_not :windows do
     it "returns a two-element Array of Integers" do
       result = Process.getrlimit Process::RLIMIT_CORE
       result.size.should == 2
-      result.first.should be_kind_of(Integer)
-      result.last.should be_kind_of(Integer)
+      result.first.should.is_a?(Integer)
+      result.last.should.is_a?(Integer)
     end
 
     context "when passed an Object" do
@@ -36,7 +36,7 @@ platform_is_not :windows do
         obj = mock("process getrlimit integer")
         obj.should_receive(:to_int).and_return(nil)
 
-        -> { Process.getrlimit(obj) }.should raise_error(TypeError)
+        -> { Process.getrlimit(obj) }.should.raise(TypeError)
       end
     end
 
@@ -49,7 +49,7 @@ platform_is_not :windows do
       end
 
       it "raises ArgumentError when passed an unknown resource" do
-        -> { Process.getrlimit(:FOO) }.should raise_error(ArgumentError)
+        -> { Process.getrlimit(:FOO) }.should.raise(ArgumentError)
       end
     end
 
@@ -62,7 +62,7 @@ platform_is_not :windows do
       end
 
       it "raises ArgumentError when passed an unknown resource" do
-        -> { Process.getrlimit("FOO") }.should raise_error(ArgumentError)
+        -> { Process.getrlimit("FOO") }.should.raise(ArgumentError)
       end
     end
 
@@ -88,4 +88,13 @@ platform_is_not :windows do
       end
     end
   end
+
+  platform_is :windows do
+    it "is not implemented" do
+      Process.respond_to?(:getrlimit).should == false
+      -> do
+        Process.getrlimit(nil)
+      end.should.raise NotImplementedError
+    end
+  end
 end
diff --git a/spec/ruby/core/process/gid_spec.rb b/spec/ruby/core/process/gid_spec.rb
index 07221da420..ca935ed520 100644
--- a/spec/ruby/core/process/gid_spec.rb
+++ b/spec/ruby/core/process/gid_spec.rb
@@ -3,8 +3,8 @@ require_relative '../../spec_helper'
 describe "Process.gid" do
   platform_is_not :windows do
     it "returns the correct gid for the user executing this process" do
-       current_gid_according_to_unix = `id -gr`.to_i
-       Process.gid.should == current_gid_according_to_unix
+      current_gid_according_to_unix = `id -gr`.to_i
+      Process.gid.should == current_gid_according_to_unix
     end
   end
 
diff --git a/spec/ruby/core/process/groups_spec.rb b/spec/ruby/core/process/groups_spec.rb
index cbbe4fed25..fa916671a4 100644
--- a/spec/ruby/core/process/groups_spec.rb
+++ b/spec/ruby/core/process/groups_spec.rb
@@ -4,6 +4,10 @@ describe "Process.groups" do
   platform_is_not :windows do
     it "gets an Array of the gids of groups in the supplemental group access list" do
       groups = `id -G`.scan(/\d+/).map { |i| i.to_i }
+      # Include the standard `id` command output.  On macOS, GNU
+      # coreutils `id` is limited to NGROUPS_MAX groups, because of
+      # the backward compatibility of getgroups(2).
+      (groups |= `/usr/bin/id -G`.scan(/\d+/).map { |i| i.to_i }) rescue nil
       gid = Process.gid
 
       expected = (groups.sort - [gid]).uniq.sort
@@ -46,7 +50,7 @@ describe "Process.groups=" do
           Process.groups.should == [ Process.gid ]
           supplementary = groups - [ Process.gid ]
           if supplementary.length > 0
-            -> { Process.groups = supplementary }.should raise_error(Errno::EPERM)
+            -> { Process.groups = supplementary }.should.raise(Errno::EPERM)
           end
         end
       end
@@ -55,7 +59,7 @@ describe "Process.groups=" do
         it "raises Errno::EPERM" do
           -> {
             Process.groups = [0]
-          }.should raise_error(Errno::EPERM)
+          }.should.raise(Errno::EPERM)
         end
       end
     end
diff --git a/spec/ruby/core/process/initgroups_spec.rb b/spec/ruby/core/process/initgroups_spec.rb
index ffc7f282b6..d9f31936cb 100644
--- a/spec/ruby/core/process/initgroups_spec.rb
+++ b/spec/ruby/core/process/initgroups_spec.rb
@@ -14,7 +14,7 @@ describe "Process.initgroups" do
           Process.groups.sort.should == augmented_groups.sort
           Process.groups = groups
         else
-          -> { Process.initgroups(name, gid) }.should raise_error(Errno::EPERM)
+          -> { Process.initgroups(name, gid) }.should.raise(Errno::EPERM)
         end
       end
     end
diff --git a/spec/ruby/core/process/kill_spec.rb b/spec/ruby/core/process/kill_spec.rb
index 4bd64a1fe8..885c2bf2b7 100644
--- a/spec/ruby/core/process/kill_spec.rb
+++ b/spec/ruby/core/process/kill_spec.rb
@@ -9,18 +9,18 @@ describe "Process.kill" do
   end
 
   it "raises an ArgumentError for unknown signals" do
-    -> { Process.kill("FOO", @pid) }.should raise_error(ArgumentError)
+    -> { Process.kill("FOO", @pid) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed a lowercase signal name" do
-    -> { Process.kill("term", @pid) }.should raise_error(ArgumentError)
+    -> { Process.kill("term", @pid) }.should.raise(ArgumentError)
   end
 
-  it "raises an ArgumentError if signal is not a Fixnum or String" do
+  it "raises an ArgumentError if signal is not an Integer or String" do
     signal = mock("process kill signal")
     signal.should_not_receive(:to_int)
 
-    -> { Process.kill(signal, @pid) }.should raise_error(ArgumentError)
+    -> { Process.kill(signal, @pid) }.should.raise(ArgumentError)
   end
 
   it "raises Errno::ESRCH if the process does not exist" do
@@ -29,7 +29,7 @@ describe "Process.kill" do
     Process.wait(pid)
     -> {
       Process.kill("SIGKILL", pid)
-    }.should raise_error(Errno::ESRCH)
+    }.should.raise(Errno::ESRCH)
   end
 
   it "checks for existence and permissions to signal a process, but does not actually signal it, when using signal 0" do
diff --git a/spec/ruby/core/process/last_status_spec.rb b/spec/ruby/core/process/last_status_spec.rb
index 3898dd6b95..1bd8adf798 100644
--- a/spec/ruby/core/process/last_status_spec.rb
+++ b/spec/ruby/core/process/last_status_spec.rb
@@ -1,20 +1,18 @@
 require_relative '../../spec_helper'
 
-ruby_version_is '2.5' do
-  describe 'Process#last_status' do
-    it 'returns the status of the last executed child process in the current thread' do
-      pid = Process.wait Process.spawn("exit 0")
-      Process.last_status.pid.should == pid
-    end
+describe 'Process#last_status' do
+  it 'returns the status of the last executed child process in the current thread' do
+    pid = Process.wait Process.spawn("exit 0")
+    Process.last_status.pid.should == pid
+  end
 
-    it 'returns nil if no child process has been ever executed in the current thread' do
-      Thread.new do
-        Process.last_status.should == nil
-      end.join
-    end
+  it 'returns nil if no child process has been ever executed in the current thread' do
+    Thread.new do
+      Process.last_status.should == nil
+    end.join
+  end
 
-    it 'raises an ArgumentError if any arguments are provided' do
-      -> { Process.last_status(1) }.should raise_error(ArgumentError)
-    end
+  it 'raises an ArgumentError if any arguments are provided' do
+    -> { Process.last_status(1) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/process/maxgroups_spec.rb b/spec/ruby/core/process/maxgroups_spec.rb
index 362f788ab2..895b384bd0 100644
--- a/spec/ruby/core/process/maxgroups_spec.rb
+++ b/spec/ruby/core/process/maxgroups_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 platform_is_not :windows do
   describe "Process.maxgroups" do
     it "returns the maximum number of gids allowed in the supplemental group access list" do
-      Process.maxgroups.should be_kind_of(Fixnum)
+      Process.maxgroups.should.is_a?(Integer)
     end
 
     it "sets the maximum number of gids allowed in the supplemental group access list" do
diff --git a/spec/ruby/core/process/pid_spec.rb b/spec/ruby/core/process/pid_spec.rb
index c5947ab50d..42b0b918b9 100644
--- a/spec/ruby/core/process/pid_spec.rb
+++ b/spec/ruby/core/process/pid_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Process.pid" do
   it "returns the process id of this process" do
     pid = Process.pid
-    pid.should be_kind_of(Fixnum)
+    pid.should.is_a?(Integer)
     Process.pid.should == pid
   end
 end
diff --git a/spec/ruby/core/process/set_proctitle_spec.rb b/spec/ruby/core/process/set_proctitle_spec.rb
index d022f2021c..28a0fa6cee 100644
--- a/spec/ruby/core/process/set_proctitle_spec.rb
+++ b/spec/ruby/core/process/set_proctitle_spec.rb
@@ -17,7 +17,7 @@ describe 'Process.setproctitle' do
       title = 'rubyspec-proctitle-test'
 
       Process.setproctitle(title).should == title
-      `ps -ocommand= -p#{$$}`.should include(title)
+      `ps -ocommand= -p#{$$}`.should.include?(title)
     end
   end
 end
diff --git a/spec/ruby/core/process/setrlimit_spec.rb b/spec/ruby/core/process/setrlimit_spec.rb
index 8bc035a4f1..f02ab46fca 100644
--- a/spec/ruby/core/process/setrlimit_spec.rb
+++ b/spec/ruby/core/process/setrlimit_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
-platform_is_not :windows do
-  describe "Process.setrlimit" do
+describe "Process.setrlimit" do
+  platform_is_not :windows do
     context "when passed an Object" do
       before do
         @resource = Process::RLIMIT_CORE
@@ -9,200 +9,196 @@ platform_is_not :windows do
       end
 
       it "calls #to_int to convert resource to an Integer" do
-        Process.setrlimit(mock_int(@resource), @limit, @max).should be_nil
+        Process.setrlimit(mock_int(@resource), @limit, @max).should == nil
       end
 
       it "raises a TypeError if #to_int for resource does not return an Integer" do
         obj = mock("process getrlimit integer")
         obj.should_receive(:to_int).and_return(nil)
 
-        -> { Process.setrlimit(obj, @limit, @max) }.should raise_error(TypeError)
+        -> { Process.setrlimit(obj, @limit, @max) }.should.raise(TypeError)
       end
 
       it "calls #to_int to convert the soft limit to an Integer" do
-        Process.setrlimit(@resource, mock_int(@limit), @max).should be_nil
+        Process.setrlimit(@resource, mock_int(@limit), @max).should == nil
       end
 
       it "raises a TypeError if #to_int for resource does not return an Integer" do
         obj = mock("process getrlimit integer")
         obj.should_receive(:to_int).and_return(nil)
 
-        -> { Process.setrlimit(@resource, obj, @max) }.should raise_error(TypeError)
+        -> { Process.setrlimit(@resource, obj, @max) }.should.raise(TypeError)
       end
 
       it "calls #to_int to convert the hard limit to an Integer" do
-        Process.setrlimit(@resource, @limit, mock_int(@max)).should be_nil
+        Process.setrlimit(@resource, @limit, mock_int(@max)).should == nil
       end
 
       it "raises a TypeError if #to_int for resource does not return an Integer" do
         obj = mock("process getrlimit integer")
         obj.should_receive(:to_int).and_return(nil)
 
-        -> { Process.setrlimit(@resource, @limit, obj) }.should raise_error(TypeError)
+        -> { Process.setrlimit(@resource, @limit, obj) }.should.raise(TypeError)
       end
     end
 
     context "when passed a Symbol" do
       platform_is_not :openbsd do
         it "coerces :AS into RLIMIT_AS" do
-          Process.setrlimit(:AS, *Process.getrlimit(Process::RLIMIT_AS)).should be_nil
+          Process.setrlimit(:AS, *Process.getrlimit(Process::RLIMIT_AS)).should == nil
         end
       end
 
       it "coerces :CORE into RLIMIT_CORE" do
-        Process.setrlimit(:CORE, *Process.getrlimit(Process::RLIMIT_CORE)).should be_nil
+        Process.setrlimit(:CORE, *Process.getrlimit(Process::RLIMIT_CORE)).should == nil
       end
 
       it "coerces :CPU into RLIMIT_CPU" do
-        Process.setrlimit(:CPU, *Process.getrlimit(Process::RLIMIT_CPU)).should be_nil
+        Process.setrlimit(:CPU, *Process.getrlimit(Process::RLIMIT_CPU)).should == nil
       end
 
       it "coerces :DATA into RLIMIT_DATA" do
-        Process.setrlimit(:DATA, *Process.getrlimit(Process::RLIMIT_DATA)).should be_nil
+        Process.setrlimit(:DATA, *Process.getrlimit(Process::RLIMIT_DATA)).should == nil
       end
 
       it "coerces :FSIZE into RLIMIT_FSIZE" do
-        Process.setrlimit(:FSIZE, *Process.getrlimit(Process::RLIMIT_FSIZE)).should be_nil
+        Process.setrlimit(:FSIZE, *Process.getrlimit(Process::RLIMIT_FSIZE)).should == nil
       end
 
       it "coerces :NOFILE into RLIMIT_NOFILE" do
-        Process.setrlimit(:NOFILE, *Process.getrlimit(Process::RLIMIT_NOFILE)).should be_nil
+        Process.setrlimit(:NOFILE, *Process.getrlimit(Process::RLIMIT_NOFILE)).should == nil
       end
 
       it "coerces :STACK into RLIMIT_STACK" do
-        Process.setrlimit(:STACK, *Process.getrlimit(Process::RLIMIT_STACK)).should be_nil
+        Process.setrlimit(:STACK, *Process.getrlimit(Process::RLIMIT_STACK)).should == nil
       end
 
-      platform_is_not :solaris, :aix do
+      platform_is_not :aix do
         it "coerces :MEMLOCK into RLIMIT_MEMLOCK" do
-          Process.setrlimit(:MEMLOCK, *Process.getrlimit(Process::RLIMIT_MEMLOCK)).should be_nil
+          Process.setrlimit(:MEMLOCK, *Process.getrlimit(Process::RLIMIT_MEMLOCK)).should == nil
         end
       end
 
-      platform_is_not :solaris do
-        it "coerces :NPROC into RLIMIT_NPROC" do
-          Process.setrlimit(:NPROC, *Process.getrlimit(Process::RLIMIT_NPROC)).should be_nil
-        end
+      it "coerces :NPROC into RLIMIT_NPROC" do
+        Process.setrlimit(:NPROC, *Process.getrlimit(Process::RLIMIT_NPROC)).should == nil
+      end
 
-        it "coerces :RSS into RLIMIT_RSS" do
-          Process.setrlimit(:RSS, *Process.getrlimit(Process::RLIMIT_RSS)).should be_nil
-        end
+      it "coerces :RSS into RLIMIT_RSS" do
+        Process.setrlimit(:RSS, *Process.getrlimit(Process::RLIMIT_RSS)).should == nil
       end
 
       platform_is :netbsd, :freebsd do
         it "coerces :SBSIZE into RLIMIT_SBSIZE" do
-          Process.setrlimit(:SBSIZE, *Process.getrlimit(Process::RLIMIT_SBSIZE)).should be_nil
+          Process.setrlimit(:SBSIZE, *Process.getrlimit(Process::RLIMIT_SBSIZE)).should == nil
         end
       end
 
       platform_is :linux do
         it "coerces :RTPRIO into RLIMIT_RTPRIO" do
-          Process.setrlimit(:RTPRIO, *Process.getrlimit(Process::RLIMIT_RTPRIO)).should be_nil
+          Process.setrlimit(:RTPRIO, *Process.getrlimit(Process::RLIMIT_RTPRIO)).should == nil
         end
 
         guard -> { defined?(Process::RLIMIT_RTTIME) } do
           it "coerces :RTTIME into RLIMIT_RTTIME" do
-            Process.setrlimit(:RTTIME, *Process.getrlimit(Process::RLIMIT_RTTIME)).should be_nil
+            Process.setrlimit(:RTTIME, *Process.getrlimit(Process::RLIMIT_RTTIME)).should == nil
           end
         end
 
         it "coerces :SIGPENDING into RLIMIT_SIGPENDING" do
-          Process.setrlimit(:SIGPENDING, *Process.getrlimit(Process::RLIMIT_SIGPENDING)).should be_nil
+          Process.setrlimit(:SIGPENDING, *Process.getrlimit(Process::RLIMIT_SIGPENDING)).should == nil
         end
 
         it "coerces :MSGQUEUE into RLIMIT_MSGQUEUE" do
-          Process.setrlimit(:MSGQUEUE, *Process.getrlimit(Process::RLIMIT_MSGQUEUE)).should be_nil
+          Process.setrlimit(:MSGQUEUE, *Process.getrlimit(Process::RLIMIT_MSGQUEUE)).should == nil
         end
 
         it "coerces :NICE into RLIMIT_NICE" do
-          Process.setrlimit(:NICE, *Process.getrlimit(Process::RLIMIT_NICE)).should be_nil
+          Process.setrlimit(:NICE, *Process.getrlimit(Process::RLIMIT_NICE)).should == nil
         end
       end
 
       it "raises ArgumentError when passed an unknown resource" do
-        -> { Process.setrlimit(:FOO, 1, 1) }.should raise_error(ArgumentError)
+        -> { Process.setrlimit(:FOO, 1, 1) }.should.raise(ArgumentError)
       end
     end
 
     context "when passed a String" do
       platform_is_not :openbsd do
         it "coerces 'AS' into RLIMIT_AS" do
-          Process.setrlimit("AS", *Process.getrlimit(Process::RLIMIT_AS)).should be_nil
+          Process.setrlimit("AS", *Process.getrlimit(Process::RLIMIT_AS)).should == nil
         end
       end
 
       it "coerces 'CORE' into RLIMIT_CORE" do
-        Process.setrlimit("CORE", *Process.getrlimit(Process::RLIMIT_CORE)).should be_nil
+        Process.setrlimit("CORE", *Process.getrlimit(Process::RLIMIT_CORE)).should == nil
       end
 
       it "coerces 'CPU' into RLIMIT_CPU" do
-        Process.setrlimit("CPU", *Process.getrlimit(Process::RLIMIT_CPU)).should be_nil
+        Process.setrlimit("CPU", *Process.getrlimit(Process::RLIMIT_CPU)).should == nil
       end
 
       it "coerces 'DATA' into RLIMIT_DATA" do
-        Process.setrlimit("DATA", *Process.getrlimit(Process::RLIMIT_DATA)).should be_nil
+        Process.setrlimit("DATA", *Process.getrlimit(Process::RLIMIT_DATA)).should == nil
       end
 
       it "coerces 'FSIZE' into RLIMIT_FSIZE" do
-        Process.setrlimit("FSIZE", *Process.getrlimit(Process::RLIMIT_FSIZE)).should be_nil
+        Process.setrlimit("FSIZE", *Process.getrlimit(Process::RLIMIT_FSIZE)).should == nil
       end
 
       it "coerces 'NOFILE' into RLIMIT_NOFILE" do
-        Process.setrlimit("NOFILE", *Process.getrlimit(Process::RLIMIT_NOFILE)).should be_nil
+        Process.setrlimit("NOFILE", *Process.getrlimit(Process::RLIMIT_NOFILE)).should == nil
       end
 
       it "coerces 'STACK' into RLIMIT_STACK" do
-        Process.setrlimit("STACK", *Process.getrlimit(Process::RLIMIT_STACK)).should be_nil
+        Process.setrlimit("STACK", *Process.getrlimit(Process::RLIMIT_STACK)).should == nil
       end
 
-      platform_is_not :solaris, :aix do
+      platform_is_not :aix do
         it "coerces 'MEMLOCK' into RLIMIT_MEMLOCK" do
-          Process.setrlimit("MEMLOCK", *Process.getrlimit(Process::RLIMIT_MEMLOCK)).should be_nil
+          Process.setrlimit("MEMLOCK", *Process.getrlimit(Process::RLIMIT_MEMLOCK)).should == nil
         end
       end
 
-      platform_is_not :solaris do
-        it "coerces 'NPROC' into RLIMIT_NPROC" do
-          Process.setrlimit("NPROC", *Process.getrlimit(Process::RLIMIT_NPROC)).should be_nil
-        end
+      it "coerces 'NPROC' into RLIMIT_NPROC" do
+        Process.setrlimit("NPROC", *Process.getrlimit(Process::RLIMIT_NPROC)).should == nil
+      end
 
-        it "coerces 'RSS' into RLIMIT_RSS" do
-          Process.setrlimit("RSS", *Process.getrlimit(Process::RLIMIT_RSS)).should be_nil
-        end
+      it "coerces 'RSS' into RLIMIT_RSS" do
+        Process.setrlimit("RSS", *Process.getrlimit(Process::RLIMIT_RSS)).should == nil
       end
 
       platform_is :netbsd, :freebsd do
         it "coerces 'SBSIZE' into RLIMIT_SBSIZE" do
-          Process.setrlimit("SBSIZE", *Process.getrlimit(Process::RLIMIT_SBSIZE)).should be_nil
+          Process.setrlimit("SBSIZE", *Process.getrlimit(Process::RLIMIT_SBSIZE)).should == nil
         end
       end
 
       platform_is :linux do
         it "coerces 'RTPRIO' into RLIMIT_RTPRIO" do
-          Process.setrlimit("RTPRIO", *Process.getrlimit(Process::RLIMIT_RTPRIO)).should be_nil
+          Process.setrlimit("RTPRIO", *Process.getrlimit(Process::RLIMIT_RTPRIO)).should == nil
         end
 
         guard -> { defined?(Process::RLIMIT_RTTIME) } do
           it "coerces 'RTTIME' into RLIMIT_RTTIME" do
-            Process.setrlimit("RTTIME", *Process.getrlimit(Process::RLIMIT_RTTIME)).should be_nil
+            Process.setrlimit("RTTIME", *Process.getrlimit(Process::RLIMIT_RTTIME)).should == nil
           end
         end
 
         it "coerces 'SIGPENDING' into RLIMIT_SIGPENDING" do
-          Process.setrlimit("SIGPENDING", *Process.getrlimit(Process::RLIMIT_SIGPENDING)).should be_nil
+          Process.setrlimit("SIGPENDING", *Process.getrlimit(Process::RLIMIT_SIGPENDING)).should == nil
         end
 
         it "coerces 'MSGQUEUE' into RLIMIT_MSGQUEUE" do
-          Process.setrlimit("MSGQUEUE", *Process.getrlimit(Process::RLIMIT_MSGQUEUE)).should be_nil
+          Process.setrlimit("MSGQUEUE", *Process.getrlimit(Process::RLIMIT_MSGQUEUE)).should == nil
         end
 
         it "coerces 'NICE' into RLIMIT_NICE" do
-          Process.setrlimit("NICE", *Process.getrlimit(Process::RLIMIT_NICE)).should be_nil
+          Process.setrlimit("NICE", *Process.getrlimit(Process::RLIMIT_NICE)).should == nil
         end
       end
 
       it "raises ArgumentError when passed an unknown resource" do
-        -> { Process.setrlimit("FOO", 1, 1) }.should raise_error(ArgumentError)
+        -> { Process.setrlimit("FOO", 1, 1) }.should.raise(ArgumentError)
       end
     end
 
@@ -217,7 +213,7 @@ platform_is_not :windows do
         obj.should_receive(:to_str).and_return("CORE")
         obj.should_not_receive(:to_int)
 
-        Process.setrlimit(obj, @limit, @max).should be_nil
+        Process.setrlimit(obj, @limit, @max).should == nil
       end
 
       it "calls #to_int if #to_str does not return a String" do
@@ -225,8 +221,17 @@ platform_is_not :windows do
         obj.should_receive(:to_str).and_return(nil)
         obj.should_receive(:to_int).and_return(@resource)
 
-        Process.setrlimit(obj, @limit, @max).should be_nil
+        Process.setrlimit(obj, @limit, @max).should == nil
       end
     end
   end
+
+  platform_is :windows do
+    it "is not implemented" do
+      Process.respond_to?(:setrlimit).should == false
+      -> do
+        Process.setrlimit(nil, nil)
+      end.should.raise NotImplementedError
+    end
+  end
 end
diff --git a/spec/ruby/core/process/spawn_spec.rb b/spec/ruby/core/process/spawn_spec.rb
index 46faced3e4..fb619dce42 100644
--- a/spec/ruby/core/process/spawn_spec.rb
+++ b/spec/ruby/core/process/spawn_spec.rb
@@ -48,10 +48,10 @@ describe "Process.spawn" do
     -> { Process.wait Process.spawn("echo spawn") }.should output_to_fd("spawn\n")
   end
 
-  it "returns the process ID of the new process as a Fixnum" do
+  it "returns the process ID of the new process as an Integer" do
     pid = Process.spawn(*ruby_exe, "-e", "exit")
     Process.wait pid
-    pid.should be_an_instance_of(Fixnum)
+    pid.should.instance_of?(Integer)
   end
 
   it "returns immediately" do
@@ -93,11 +93,11 @@ describe "Process.spawn" do
     end
 
     it "raises an ArgumentError if the command includes a null byte" do
-      -> { Process.spawn "\000" }.should raise_error(ArgumentError)
+      -> { Process.spawn "\000" }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if the argument does not respond to #to_str" do
-      -> { Process.spawn :echo }.should raise_error(TypeError)
+      -> { Process.spawn :echo }.should.raise(TypeError)
     end
   end
 
@@ -122,11 +122,11 @@ describe "Process.spawn" do
     end
 
     it "raises an ArgumentError if an argument includes a null byte" do
-      -> { Process.spawn "echo", "\000" }.should raise_error(ArgumentError)
+      -> { Process.spawn "echo", "\000" }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if an argument does not respond to #to_str" do
-      -> { Process.spawn "echo", :foo }.should raise_error(TypeError)
+      -> { Process.spawn "echo", :foo }.should.raise(TypeError)
     end
   end
 
@@ -178,19 +178,19 @@ describe "Process.spawn" do
     end
 
     it "raises an ArgumentError if the Array does not have exactly two elements" do
-      -> { Process.spawn([]) }.should raise_error(ArgumentError)
-      -> { Process.spawn([:a]) }.should raise_error(ArgumentError)
-      -> { Process.spawn([:a, :b, :c]) }.should raise_error(ArgumentError)
+      -> { Process.spawn([]) }.should.raise(ArgumentError)
+      -> { Process.spawn([:a]) }.should.raise(ArgumentError)
+      -> { Process.spawn([:a, :b, :c]) }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError if the Strings in the Array include a null byte" do
-      -> { Process.spawn ["\000", "echo"] }.should raise_error(ArgumentError)
-      -> { Process.spawn ["echo", "\000"] }.should raise_error(ArgumentError)
+      -> { Process.spawn ["\000", "echo"] }.should.raise(ArgumentError)
+      -> { Process.spawn ["echo", "\000"] }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if an element in the Array does not respond to #to_str" do
-      -> { Process.spawn ["echo", :echo] }.should raise_error(TypeError)
-      -> { Process.spawn [:echo, "echo"] }.should raise_error(TypeError)
+      -> { Process.spawn ["echo", :echo] }.should.raise(TypeError)
+      -> { Process.spawn [:echo, "echo"] }.should.raise(TypeError)
     end
   end
 
@@ -207,13 +207,29 @@ describe "Process.spawn" do
 
   it "unsets environment variables whose value is nil" do
     ENV["FOO"] = "BAR"
-    Process.wait Process.spawn({"FOO" => nil}, "echo #{@var}>#{@name}")
-    expected = "\n"
-    platform_is :windows do
-      # Windows does not expand the variable if it is unset
-      expected = "#{@var}\n"
+    -> do
+      Process.wait Process.spawn({"FOO" => nil}, ruby_cmd("p ENV['FOO']"))
+    end.should output_to_fd("nil\n")
+  end
+
+  platform_is_not :windows do
+    it "uses the passed env['PATH'] to search the executable" do
+      dir = tmp("spawn_path_dir")
+      mkdir_p dir
+      begin
+        exe = 'process-spawn-executable-in-path'
+        path = "#{dir}/#{exe}"
+        File.write(path, "#!/bin/sh\necho $1")
+        File.chmod(0755, path)
+
+        env = { "PATH" => "#{dir}#{File::PATH_SEPARATOR}#{ENV['PATH']}" }
+        Process.wait Process.spawn(env, exe, 'OK', out: @name)
+        $?.should.success?
+        File.read(@name).should == "OK\n"
+      ensure
+        rm_r dir
+      end
     end
-    File.read(@name).should == expected
   end
 
   it "calls #to_hash to convert the environment" do
@@ -240,19 +256,19 @@ describe "Process.spawn" do
   it "raises an ArgumentError if an environment key includes an equals sign" do
     -> do
       Process.spawn({"FOO=" => "BAR"}, "echo #{@var}>#{@name}")
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if an environment key includes a null byte" do
     -> do
       Process.spawn({"\000" => "BAR"}, "echo #{@var}>#{@name}")
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if an environment value includes a null byte" do
     -> do
       Process.spawn({"FOO" => "\000"}, "echo #{@var}>#{@name}")
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   # :unsetenv_others
@@ -269,7 +285,7 @@ describe "Process.spawn" do
     it "unsets other environment variables when given a true :unsetenv_others option" do
       ENV["FOO"] = "BAR"
       Process.wait Process.spawn(*@common_env_spawn_args, unsetenv_others: true)
-      $?.success?.should be_true
+      $?.success?.should == true
       File.read(@name).should == "\n"
     end
   end
@@ -277,7 +293,7 @@ describe "Process.spawn" do
   it "does not unset other environment variables when given a false :unsetenv_others option" do
     ENV["FOO"] = "BAR"
     Process.wait Process.spawn(*@common_env_spawn_args, unsetenv_others: false)
-    $?.success?.should be_true
+    $?.success?.should == true
     File.read(@name).should == "BAR\n"
   end
 
@@ -285,7 +301,7 @@ describe "Process.spawn" do
     it "does not unset environment variables included in the environment hash" do
       env = @minimal_env.merge({"FOO" => "BAR"})
       Process.wait Process.spawn(env, "echo #{@var}>#{@name}", unsetenv_others: true)
-      $?.success?.should be_true
+      $?.success?.should == true
       File.read(@name).should == "BAR\n"
     end
   end
@@ -331,23 +347,33 @@ describe "Process.spawn" do
 
     it "joins the specified process group if pgroup: pgid" do
       pgid = Process.getpgid(Process.pid)
-      -> do
-        Process.wait Process.spawn(ruby_cmd("print Process.getpgid(Process.pid)"), pgroup: pgid)
-      end.should output_to_fd(pgid.to_s)
+      # The process group is not available on all platforms.
+      # See "man proc" - /proc/[pid]/stat - (5) pgrp
+      # In Travis aarch64 environment, the value is 0.
+      #
+      # $ cat /proc/[pid]/stat
+      # 19179 (ruby) S 19160 0 0 ...
+      unless pgid.zero?
+        -> do
+          Process.wait Process.spawn(ruby_cmd("print Process.getpgid(Process.pid)"), pgroup: pgid)
+        end.should output_to_fd(pgid.to_s)
+      else
+        skip "The process group is not available."
+      end
     end
 
     it "raises an ArgumentError if given a negative :pgroup option" do
-      -> { Process.spawn("echo", pgroup: -1) }.should raise_error(ArgumentError)
+      -> { Process.spawn("echo", pgroup: -1) }.should.raise(ArgumentError)
     end
 
     it "raises a TypeError if given a symbol as :pgroup option" do
-      -> { Process.spawn("echo", pgroup: :true) }.should raise_error(TypeError)
+      -> { Process.spawn("echo", pgroup: :true) }.should.raise(TypeError)
     end
   end
 
   platform_is :windows do
     it "raises an ArgumentError if given :pgroup option" do
-      -> { Process.spawn("echo", pgroup: false) }.should raise_error(ArgumentError)
+      -> { Process.spawn("echo", pgroup: false) }.should.raise(ArgumentError)
     end
   end
 
@@ -409,7 +435,7 @@ describe "Process.spawn" do
 
       it "kills extra chdir processes" do
         pid = nil
-        Dir.chdir("/tmp") do
+        Dir.chdir("/") do
           pid = Process.spawn("sleep 10")
         end
 
@@ -426,7 +452,7 @@ describe "Process.spawn" do
           children.each do |child|
             -> do
               Process.kill("TERM", child)
-            end.should raise_error(Errno::ESRCH)
+            end.should.raise(Errno::ESRCH)
           end
         end
       end
@@ -451,7 +477,17 @@ describe "Process.spawn" do
 
   # redirection
 
-  it "redirects STDOUT to the given file descriptor if out: Fixnum" do
+  it 'redirects to the wrapped IO using wrapped_io.to_io if out: wrapped_io' do
+    File.open(@name, 'w') do |file|
+      -> do
+        wrapped_io = mock('wrapped IO')
+        wrapped_io.should_receive(:to_io).and_return(file)
+        Process.wait Process.spawn('echo Hello World', out: wrapped_io)
+      end.should output_to_fd("Hello World\n", file)
+    end
+  end
+
+  it "redirects STDOUT to the given file descriptor if out: Integer" do
     File.open(@name, 'w') do |file|
       -> do
         Process.wait Process.spawn("echo glark", out: file.fileno)
@@ -477,7 +513,7 @@ describe "Process.spawn" do
     File.read(@name).should == "glark\n"
   end
 
-  it "redirects STDERR to the given file descriptor if err: Fixnum" do
+  it "redirects STDERR to the given file descriptor if err: Integer" do
     File.open(@name, 'w') do |file|
       -> do
         Process.wait Process.spawn("echo glark>&2", err: file.fileno)
@@ -530,31 +566,47 @@ describe "Process.spawn" do
     File.read(@name).should == "glarkbang"
   end
 
-  # :close_others
+  platform_is_not :windows, :android do
+    it "closes STDERR in the child if :err => :close" do
+      File.open(@name, 'w') do |file|
+        -> do
+          code = "begin; STDOUT.puts 'out'; STDERR.puts 'hello'; rescue => e; puts 'rescued'; end"
+          Process.wait Process.spawn(ruby_cmd(code), :out => file, :err => :close)
+        end.should output_to_fd("out\nrescued\n", file)
+      end
+    end
+  end
 
   platform_is_not :windows do
-    context "defaults :close_others to" do
-      ruby_version_is ""..."2.6" do
-        it "true" do
-          IO.pipe do |r, w|
-            w.close_on_exec = false
-            code = "begin; IO.new(#{w.fileno}).close; rescue Errno::EBADF; puts 'not inherited'; end"
-            Process.wait Process.spawn(ruby_cmd(code), :out => @name)
-            File.read(@name).should == "not inherited\n"
-          end
-        end
+    it "redirects non-default file descriptor to itself" do
+      File.open(@name, 'w') do |file|
+        -> do
+          Process.wait Process.spawn(
+            ruby_cmd("f = IO.new(#{file.fileno}, 'w'); f.print(:bang); f.flush"), file.fileno => file.fileno)
+        end.should output_to_fd("bang", file)
       end
+    end
+  end
 
-      ruby_version_is "2.6" do
-        it "false" do
-          IO.pipe do |r, w|
-            w.close_on_exec = false
-            code = "io = IO.new(#{w.fileno}); io.puts('inherited'); io.close"
-            pid = Process.spawn(ruby_cmd(code))
-            w.close
-            Process.wait(pid)
-            r.read.should == "inherited\n"
-          end
+  it "redirects default file descriptor to itself" do
+    -> do
+      Process.wait Process.spawn(
+        ruby_cmd("f = IO.new(#{STDOUT.fileno}, 'w'); f.print(:bang); f.flush"), STDOUT.fileno => STDOUT.fileno)
+    end.should output_to_fd("bang", STDOUT)
+  end
+
+  # :close_others
+
+  platform_is_not :windows do
+    context "defaults :close_others to" do
+      it "false" do
+        IO.pipe do |r, w|
+          w.close_on_exec = false
+          code = "io = IO.new(#{w.fileno}); io.puts('inherited'); io.close"
+          pid = Process.spawn(ruby_cmd(code))
+          w.close
+          Process.wait(pid)
+          r.read.should == "inherited\n"
         end
       end
     end
@@ -626,53 +678,93 @@ describe "Process.spawn" do
   # error handling
 
   it "raises an ArgumentError if passed no command arguments" do
-    -> { Process.spawn }.should raise_error(ArgumentError)
+    -> { Process.spawn }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed env or options but no command arguments" do
-    -> { Process.spawn({}) }.should raise_error(ArgumentError)
+    -> { Process.spawn({}) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed env and options but no command arguments" do
-    -> { Process.spawn({}, {}) }.should raise_error(ArgumentError)
+    -> { Process.spawn({}, {}) }.should.raise(ArgumentError)
   end
 
   it "raises an Errno::ENOENT for an empty string" do
-    -> { Process.spawn "" }.should raise_error(Errno::ENOENT)
+    -> { Process.spawn "" }.should.raise(Errno::ENOENT)
   end
 
   it "raises an Errno::ENOENT if the command does not exist" do
-    -> { Process.spawn "nonesuch" }.should raise_error(Errno::ENOENT)
+    -> { Process.spawn "nonesuch" }.should.raise(Errno::ENOENT, "No such file or directory - nonesuch")
+  end
+
+  it "sets $? to exit status 127 when the command does not exist" do
+    Process.spawn("nonesuch") rescue nil
+    $?.exitstatus.should == 127
+  end
+
+  it "raises an Errno::ENOENT if the file does not exist" do
+    -> { Process.spawn "./nonesuch" }.should.raise(Errno::ENOENT, "No such file or directory - ./nonesuch")
+  end
+
+  it "sets $? to exit status 127 when the file does not exist" do
+    Process.spawn("./nonesuch") rescue nil
+    $?.exitstatus.should == 127
+  end
+
+  platform_is_not :windows do
+    it "raises an Errno::EACCES when the path is a directory" do
+      -> { Process.spawn "./" }.should.raise(Errno::EACCES, "Permission denied - ./")
+    end
   end
 
   unless File.executable?(__FILE__) # Some FS (e.g. vboxfs) locate all files executable
     platform_is_not :windows do
       it "raises an Errno::EACCES when the file does not have execute permissions" do
-        -> { Process.spawn __FILE__ }.should raise_error(Errno::EACCES)
+        -> { Process.spawn __FILE__ }.should.raise(Errno::EACCES, "Permission denied - #{__FILE__}")
+      end
+
+      it "sets $? to exit status 127 when the file does not have execute permissions" do
+        Process.spawn(__FILE__) rescue nil
+        $?.exitstatus.should == 127
+      end
+
+      it "raises an Errno::ENOENT when a non-executable file is found in PATH" do
+        dir = tmp("spawn_path_non_executable_dir")
+        mkdir_p dir
+        begin
+          exe = 'process-spawn-non-executable-in-path'
+          File.write("#{dir}/#{exe}", "#!/bin/sh\necho hi")
+          File.chmod(0644, "#{dir}/#{exe}")
+          env = { "PATH" => "#{dir}#{File::PATH_SEPARATOR}#{ENV['PATH']}" }
+          -> { Process.spawn(env, exe) }.should.raise(Errno::ENOENT, "No such file or directory - #{exe}")
+          $?.exitstatus.should == 127
+        ensure
+          rm_r dir
+        end
       end
     end
 
     platform_is :windows do
       it "raises Errno::EACCES or Errno::ENOEXEC when the file is not an executable file" do
-        -> { Process.spawn __FILE__ }.should raise_error(SystemCallError) { |e|
-          [Errno::EACCES, Errno::ENOEXEC].should include(e.class)
+        -> { Process.spawn __FILE__ }.should.raise(SystemCallError) { |e|
+          [Errno::EACCES, Errno::ENOEXEC].should.include?(e.class)
         }
       end
     end
   end
 
   it "raises an Errno::EACCES or Errno::EISDIR when passed a directory" do
-    -> { Process.spawn File.dirname(__FILE__) }.should raise_error(SystemCallError) { |e|
-      [Errno::EACCES, Errno::EISDIR].should include(e.class)
+    -> { Process.spawn __dir__ }.should.raise(SystemCallError) { |e|
+      [Errno::EACCES, Errno::EISDIR].should.include?(e.class)
     }
   end
 
   it "raises an ArgumentError when passed a string key in options" do
-    -> { Process.spawn("echo", "chdir" => Dir.pwd) }.should raise_error(ArgumentError)
+    -> { Process.spawn("echo", "chdir" => Dir.pwd) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when passed an unknown option key" do
-    -> { Process.spawn("echo", nonesuch: :foo) }.should raise_error(ArgumentError)
+    -> { Process.spawn("echo", nonesuch: :foo) }.should.raise(ArgumentError)
   end
 
   platform_is_not :windows, :aix do
@@ -689,13 +781,15 @@ describe "Process.spawn" do
       end
 
       it "maps the key to a file descriptor in the child that inherits the file descriptor from the parent specified by the value" do
-        child_fd = find_unused_fd
-        args = ruby_cmd(fixture(__FILE__, "map_fd.rb"), args: [child_fd.to_s])
-        pid = Process.spawn(*args, { child_fd => @io })
-        Process.waitpid pid
-        @io.rewind
-
-        @io.read.should == "writing to fd: #{child_fd}"
+        File.open(__FILE__, "r") do |f|
+          child_fd = f.fileno
+          args = ruby_cmd(fixture(__FILE__, "map_fd.rb"), args: [child_fd.to_s])
+          pid = Process.spawn(*args, { child_fd => @io })
+          Process.waitpid pid
+          @io.rewind
+
+          @io.read.should == "writing to fd: #{child_fd}"
+        end
       end
     end
   end
diff --git a/spec/ruby/core/process/status/bit_and_spec.rb b/spec/ruby/core/process/status/bit_and_spec.rb
index 97f768fdc1..a5b1123e90 100644
--- a/spec/ruby/core/process/status/bit_and_spec.rb
+++ b/spec/ruby/core/process/status/bit_and_spec.rb
@@ -1,5 +1,38 @@
 require_relative '../../../spec_helper'
 
-describe "Process::Status#&" do
-  it "needs to be reviewed for spec completeness"
+ruby_version_is ""..."4.0" do
+
+  describe "Process::Status#&" do
+    it "returns a bitwise and of the integer status of an exited child" do
+      suppress_warning do
+        ruby_exe("exit(29)", exit_status: 29)
+        ($? & 0).should == 0
+        ($? & $?.to_i).should == $?.to_i
+
+        # Actual value is implementation specific
+        platform_is :linux do
+          # 29 == 0b11101
+          ($? & 0b1011100000000).should == 0b1010100000000
+        end
+      end
+    end
+
+    ruby_version_is ""..."4.0" do
+      it "raises an ArgumentError if mask is negative" do
+        suppress_warning do
+          ruby_exe("exit(0)")
+          -> {
+            $? & -1
+          }.should.raise(ArgumentError, 'negative mask value: -1')
+        end
+      end
+
+      it "shows a deprecation warning" do
+        ruby_exe("exit(0)")
+        -> {
+          $? & 0
+        }.should complain(/warning: Process::Status#& is deprecated and will be removed .*use other Process::Status predicates instead/)
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/process/status/equal_value_spec.rb b/spec/ruby/core/process/status/equal_value_spec.rb
index 9e9a2d0a2b..d8a2be26b8 100644
--- a/spec/ruby/core/process/status/equal_value_spec.rb
+++ b/spec/ruby/core/process/status/equal_value_spec.rb
@@ -1,5 +1,15 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#==" do
-  it "needs to be reviewed for spec completeness"
+  it "returns true when compared to the integer status of an exited child" do
+    ruby_exe("exit(29)", exit_status: 29)
+    $?.to_i.should == $?
+    $?.should == $?.to_i
+  end
+
+  it "returns true when compared to the integer status of a terminated child" do
+    ruby_exe("Process.kill(:KILL, $$); exit(29)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
+    $?.to_i.should == $?
+    $?.should == $?.to_i
+  end
 end
diff --git a/spec/ruby/core/process/status/exited_spec.rb b/spec/ruby/core/process/status/exited_spec.rb
index 0ae3f9e7ae..ad14b35000 100644
--- a/spec/ruby/core/process/status/exited_spec.rb
+++ b/spec/ruby/core/process/status/exited_spec.rb
@@ -1,37 +1,32 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#exited?" do
-
   describe "for a child that exited normally" do
-
     before :each do
       ruby_exe("exit(0)")
     end
 
     it "returns true" do
-      $?.exited?.should be_true
+      $?.exited?.should == true
     end
   end
 
 
   describe "for a terminated child" do
-
     before :each do
-      ruby_exe("Process.kill(:KILL, $$); exit(42)")
+      ruby_exe("Process.kill(:KILL, $$); exit(42)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
     end
 
     platform_is_not :windows do
       it "returns false" do
-        $?.exited?.should be_false
+        $?.exited?.should == false
       end
     end
 
     platform_is :windows do
       it "always returns true" do
-        $?.exited?.should be_true
+        $?.exited?.should == true
       end
     end
-
   end
-
 end
diff --git a/spec/ruby/core/process/status/exitstatus_spec.rb b/spec/ruby/core/process/status/exitstatus_spec.rb
index cd46b2081f..5c86c2b3c8 100644
--- a/spec/ruby/core/process/status/exitstatus_spec.rb
+++ b/spec/ruby/core/process/status/exitstatus_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../../spec_helper'
 
 describe "Process::Status#exitstatus" do
   before :each do
-    ruby_exe("exit(42)")
+    ruby_exe("exit(42)", exit_status: 42)
   end
 
   it "returns the process exit code" do
@@ -11,7 +11,7 @@ describe "Process::Status#exitstatus" do
 
   describe "for a child that raised SignalException" do
     before :each do
-      ruby_exe("raise SignalException, 'SIGTERM'")
+      ruby_exe("Process.kill(:KILL, $$); exit(42)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
     end
 
     platform_is_not :windows do
diff --git a/spec/ruby/core/process/status/right_shift_spec.rb b/spec/ruby/core/process/status/right_shift_spec.rb
index e9dda437e8..5689526f54 100644
--- a/spec/ruby/core/process/status/right_shift_spec.rb
+++ b/spec/ruby/core/process/status/right_shift_spec.rb
@@ -1,5 +1,37 @@
 require_relative '../../../spec_helper'
 
-describe "Process::Status#>>" do
-  it "needs to be reviewed for spec completeness"
+ruby_version_is ""..."4.0" do
+
+  describe "Process::Status#>>" do
+    it "returns a right shift of the integer status of an exited child" do
+      suppress_warning do
+        ruby_exe("exit(29)", exit_status: 29)
+        ($? >> 0).should == $?.to_i
+        ($? >> 1).should == $?.to_i >> 1
+
+        # Actual value is implementation specific
+        platform_is :linux do
+          ($? >> 8).should == 29
+        end
+      end
+    end
+
+    ruby_version_is ""..."4.0" do
+      it "raises an ArgumentError if shift value is negative" do
+        suppress_warning do
+          ruby_exe("exit(0)")
+          -> {
+            $? >> -1
+          }.should.raise(ArgumentError, 'negative shift value: -1')
+        end
+      end
+
+      it "shows a deprecation warning" do
+        ruby_exe("exit(0)")
+        -> {
+          $? >> 0
+        }.should complain(/warning: Process::Status#>> is deprecated and will be removed .*use other Process::Status attributes instead/)
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/process/status/signaled_spec.rb b/spec/ruby/core/process/status/signaled_spec.rb
index f23c95025f..8cf409bb42 100644
--- a/spec/ruby/core/process/status/signaled_spec.rb
+++ b/spec/ruby/core/process/status/signaled_spec.rb
@@ -1,35 +1,31 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#signaled?" do
-
   describe "for a cleanly exited child" do
-
     before :each do
       ruby_exe("exit(0)")
     end
 
     it "returns false" do
-      $?.signaled?.should be_false
+      $?.signaled?.should == false
     end
   end
 
   describe "for a terminated child" do
-
     before :each do
-      ruby_exe("Process.kill(:KILL, $$); exit(42)")
+      ruby_exe("Process.kill(:KILL, $$); exit(42)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
     end
 
     platform_is_not :windows do
       it "returns true" do
-        $?.signaled?.should be_true
+        $?.signaled?.should == true
       end
     end
 
     platform_is :windows do
       it "always returns false" do
-        $?.signaled?.should be_false
+        $?.signaled?.should == false
       end
     end
-
   end
 end
diff --git a/spec/ruby/core/process/status/success_spec.rb b/spec/ruby/core/process/status/success_spec.rb
index 28a1721800..f61243c667 100644
--- a/spec/ruby/core/process/status/success_spec.rb
+++ b/spec/ruby/core/process/status/success_spec.rb
@@ -1,51 +1,41 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#success?" do
-
   describe "for a child that exited normally" do
-
     before :each do
       ruby_exe("exit(0)")
     end
 
     it "returns true" do
-      $?.success?.should be_true
+      $?.success?.should == true
     end
   end
 
   describe "for a child that exited with a non zero status" do
-
     before :each do
-      ruby_exe("exit(42)")
+      ruby_exe("exit(42)", exit_status: 42)
     end
 
     it "returns false" do
-      $?.success?.should be_false
+      $?.success?.should == false
     end
   end
 
   describe "for a child that was terminated" do
-
     before :each do
-      ruby_exe("Process.kill(:KILL, $$); exit(42)")
+      ruby_exe("Process.kill(:KILL, $$); exit(42)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
     end
 
     platform_is_not :windows do
-
       it "returns nil" do
-        $?.success?.should be_nil
+        $?.success?.should == nil
       end
-
     end
 
     platform_is :windows do
-
       it "always returns true" do
-        $?.success?.should be_true
+        $?.success?.should == true
       end
-
     end
-
   end
-
 end
diff --git a/spec/ruby/core/process/status/termsig_spec.rb b/spec/ruby/core/process/status/termsig_spec.rb
index 1482d27146..1d57724d12 100644
--- a/spec/ruby/core/process/status/termsig_spec.rb
+++ b/spec/ruby/core/process/status/termsig_spec.rb
@@ -1,21 +1,19 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#termsig" do
-
   describe "for a child that exited normally" do
-
     before :each do
       ruby_exe("exit(0)")
     end
 
-    it "returns true" do
-      $?.termsig.should be_nil
+    it "returns nil" do
+      $?.termsig.should == nil
     end
   end
 
   describe "for a child that raised SignalException" do
     before :each do
-      ruby_exe("raise SignalException, 'SIGTERM'")
+      ruby_exe("raise SignalException, 'SIGTERM'", exit_status: :SIGTERM)
     end
 
     platform_is_not :windows do
@@ -26,26 +24,20 @@ describe "Process::Status#termsig" do
   end
 
   describe "for a child that was sent a signal" do
-
     before :each do
-      ruby_exe("Process.kill(:KILL, $$); exit(42)")
+      ruby_exe("Process.kill(:KILL, $$); exit(42)", exit_status: platform_is(:windows) ? 0 : :SIGKILL)
     end
 
     platform_is_not :windows do
-
       it "returns the signal" do
         $?.termsig.should == Signal.list["KILL"]
       end
-
     end
 
     platform_is :windows do
-
       it "always returns nil" do
-        $?.termsig.should be_nil
+        $?.termsig.should == nil
       end
-
     end
-
   end
 end
diff --git a/spec/ruby/core/process/status/to_i_spec.rb b/spec/ruby/core/process/status/to_i_spec.rb
index 37b7bdb1e4..0bfb883d23 100644
--- a/spec/ruby/core/process/status/to_i_spec.rb
+++ b/spec/ruby/core/process/status/to_i_spec.rb
@@ -1,5 +1,13 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Status#to_i" do
-  it "needs to be reviewed for spec completeness"
+  it "returns an integer when the child exits" do
+    ruby_exe('exit 48', exit_status: 48)
+    $?.to_i.should.instance_of?(Integer)
+  end
+
+  it "returns an integer when the child is signaled" do
+    ruby_exe('raise SignalException, "TERM"', exit_status: platform_is(:windows) ? 3 : :SIGTERM)
+    $?.to_i.should.instance_of?(Integer)
+  end
 end
diff --git a/spec/ruby/core/process/status/wait_spec.rb b/spec/ruby/core/process/status/wait_spec.rb
new file mode 100644
index 0000000000..18ecc14f6f
--- /dev/null
+++ b/spec/ruby/core/process/status/wait_spec.rb
@@ -0,0 +1,100 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/common'
+
+describe "Process::Status.wait" do
+  ProcessSpecs.use_system_ruby(self)
+
+  before :all do
+    begin
+      leaked = Process.waitall
+      # Ruby-space should not see PIDs used by rjit
+      raise "subprocesses leaked before wait specs: #{leaked}" unless leaked.empty?
+    rescue NotImplementedError
+    end
+  end
+
+  it "returns a status with pid -1 if there are no child processes" do
+    Process::Status.wait.pid.should == -1
+  end
+
+  platform_is_not :windows do
+    it "returns a status with its child pid" do
+      pid = Process.spawn(ruby_cmd('exit'))
+      status = Process::Status.wait
+      status.should.instance_of?(Process::Status)
+      status.pid.should == pid
+    end
+
+    it "should not set $? to the Process::Status" do
+      pid = Process.spawn(ruby_cmd('exit'))
+      status = Process::Status.wait
+      $?.should_not.equal?(status)
+    end
+
+    it "should not change the value of $?" do
+      pid = Process.spawn(ruby_cmd('exit'))
+      Process.wait
+      status = $?
+      Process::Status.wait
+      status.should.equal?($?)
+    end
+
+    it "waits for any child process if no pid is given" do
+      pid = Process.spawn(ruby_cmd('exit'))
+      Process::Status.wait.pid.should == pid
+      -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
+    end
+
+    it "waits for a specific child if a pid is given" do
+      pid1 = Process.spawn(ruby_cmd('exit'))
+      pid2 = Process.spawn(ruby_cmd('exit'))
+      Process::Status.wait(pid2).pid.should == pid2
+      Process::Status.wait(pid1).pid.should == pid1
+      -> { Process.kill(0, pid1) }.should.raise(Errno::ESRCH)
+      -> { Process.kill(0, pid2) }.should.raise(Errno::ESRCH)
+    end
+
+    it "coerces the pid to an Integer" do
+      pid1 = Process.spawn(ruby_cmd('exit'))
+      Process::Status.wait(mock_int(pid1)).pid.should == pid1
+      -> { Process.kill(0, pid1) }.should.raise(Errno::ESRCH)
+    end
+
+    # This spec is probably system-dependent.
+    it "waits for a child whose process group ID is that of the calling process" do
+      pid1 = Process.spawn(ruby_cmd('exit'), pgroup: true)
+      pid2 = Process.spawn(ruby_cmd('exit'))
+
+      Process::Status.wait(0).pid.should == pid2
+      Process::Status.wait.pid.should == pid1
+    end
+
+    # This spec is probably system-dependent.
+    it "doesn't block if no child is available when WNOHANG is used" do
+      read, write = IO.pipe
+      pid = Process.fork do
+        read.close
+        Signal.trap("TERM") { Process.exit! }
+        write << 1
+        write.close
+        sleep
+      end
+
+      Process::Status.wait(pid, Process::WNOHANG).should == nil
+
+      # wait for the child to setup its TERM handler
+      write.close
+      read.read(1)
+      read.close
+
+      Process.kill("TERM", pid)
+      Process::Status.wait.pid.should == pid
+    end
+
+    it "always accepts flags=0" do
+      pid = Process.spawn(ruby_cmd('exit'))
+      Process::Status.wait(-1, 0).pid.should == pid
+      -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
+    end
+  end
+end
diff --git a/spec/ruby/core/process/times_spec.rb b/spec/ruby/core/process/times_spec.rb
index 07b4fa5c9f..a7ffbb79e5 100644
--- a/spec/ruby/core/process/times_spec.rb
+++ b/spec/ruby/core/process/times_spec.rb
@@ -2,26 +2,18 @@ require_relative '../../spec_helper'
 
 describe "Process.times" do
   it "returns a Process::Tms" do
-    Process.times.should be_kind_of(Process::Tms)
+    Process.times.should.is_a?(Process::Tms)
   end
 
-  it "returns current cpu times" do
-    t = Process.times
+  # TODO: Intel C Compiler does not work this example
+  # http://rubyci.s3.amazonaws.com/icc-x64/ruby-master/log/20221013T030005Z.fail.html.gz
+  unless RbConfig::CONFIG['CC']&.include?("icx")
+    it "returns current cpu times" do
+      t = Process.times
+      user = t.utime
 
-    # Do busy work for a wall-clock interval.
-    start = Time.now
-    1 until (Time.now - start) > 0.5
-
-    # Ensure times is larger. NOTE that there is no
-    # guarantee of an upper bound since anything may be
-    # happening at the OS level, so we ONLY check that at
-    # least an interval has elapsed. Also, we are assuming
-    # there is a correlation between wall clock time and
-    # process time. In practice, there is an observed
-    # discrepancy often 10% or greater. In other words,
-    # this is a very fuzzy test.
-    t2 = Process.times
-    diff = (t2.utime + t2.stime) - (t.utime + t.stime)
-    diff.should > 0
+      1 until Process.times.utime > user
+      Process.times.utime.should > user
+    end
   end
 end
diff --git a/spec/ruby/core/process/tms/cstime_spec.rb b/spec/ruby/core/process/tms/cstime_spec.rb
index 207d4391c0..9c2d9e8632 100644
--- a/spec/ruby/core/process/tms/cstime_spec.rb
+++ b/spec/ruby/core/process/tms/cstime_spec.rb
@@ -1,9 +1,17 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Tms#cstime" do
-  it "needs to be reviewed for spec completeness"
+  it "returns cstime attribute" do
+    cstime = Object.new
+    Process::Tms.new(nil, nil, nil, cstime).cstime.should == cstime
+  end
 end
 
 describe "Process::Tms#cstime=" do
-  it "needs to be reviewed for spec completeness"
+  it "assigns a value to the cstime attribute" do
+    cstime = Object.new
+    tms = Process::Tms.new
+    tms.cstime = cstime
+    tms.cstime.should == cstime
+  end
 end
diff --git a/spec/ruby/core/process/tms/cutime_spec.rb b/spec/ruby/core/process/tms/cutime_spec.rb
index 390280f005..0ac3ff1964 100644
--- a/spec/ruby/core/process/tms/cutime_spec.rb
+++ b/spec/ruby/core/process/tms/cutime_spec.rb
@@ -1,9 +1,17 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Tms#cutime" do
-  it "needs to be reviewed for spec completeness"
+  it "returns cutime attribute" do
+    cutime = Object.new
+    Process::Tms.new(nil, nil, cutime, nil).cutime.should == cutime
+  end
 end
 
 describe "Process::Tms#cutime=" do
-  it "needs to be reviewed for spec completeness"
+  it "assigns a value to the cutime attribute" do
+    cutime = Object.new
+    tms = Process::Tms.new
+    tms.cutime = cutime
+    tms.cutime.should == cutime
+  end
 end
diff --git a/spec/ruby/core/process/tms/element_reference_spec.rb b/spec/ruby/core/process/tms/element_reference_spec.rb
deleted file mode 100644
index 84a34089ae..0000000000
--- a/spec/ruby/core/process/tms/element_reference_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Process::Tms.[]" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/process/tms/members_spec.rb b/spec/ruby/core/process/tms/members_spec.rb
deleted file mode 100644
index 005a8baec1..0000000000
--- a/spec/ruby/core/process/tms/members_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Process::Tms.members" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/process/tms/new_spec.rb b/spec/ruby/core/process/tms/new_spec.rb
deleted file mode 100644
index 9dd1f5a8f2..0000000000
--- a/spec/ruby/core/process/tms/new_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../../spec_helper'
-
-describe "Process::Tms.new" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/core/process/tms/stime_spec.rb b/spec/ruby/core/process/tms/stime_spec.rb
index 4104b625e2..1e8371475f 100644
--- a/spec/ruby/core/process/tms/stime_spec.rb
+++ b/spec/ruby/core/process/tms/stime_spec.rb
@@ -1,9 +1,17 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Tms#stime" do
-  it "needs to be reviewed for spec completeness"
+  it "returns stime attribute" do
+    stime = Object.new
+    Process::Tms.new(nil, stime, nil, nil).stime.should == stime
+  end
 end
 
 describe "Process::Tms#stime=" do
-  it "needs to be reviewed for spec completeness"
+  it "assigns a value to the stime attribute" do
+    stime = Object.new
+    tms = Process::Tms.new
+    tms.stime = stime
+    tms.stime.should == stime
+  end
 end
diff --git a/spec/ruby/core/process/tms/utime_spec.rb b/spec/ruby/core/process/tms/utime_spec.rb
index 28371590e9..403a31e2e6 100644
--- a/spec/ruby/core/process/tms/utime_spec.rb
+++ b/spec/ruby/core/process/tms/utime_spec.rb
@@ -1,9 +1,17 @@
 require_relative '../../../spec_helper'
 
 describe "Process::Tms#utime" do
-  it "needs to be reviewed for spec completeness"
+  it "returns utime attribute" do
+    utime = Object.new
+    Process::Tms.new(utime, nil, nil, nil).utime.should == utime
+  end
 end
 
 describe "Process::Tms#utime=" do
-  it "needs to be reviewed for spec completeness"
+  it "assigns a value to the ctime attribute" do
+    utime = Object.new
+    tms = Process::Tms.new
+    tms.utime = utime
+    tms.utime.should == utime
+  end
 end
diff --git a/spec/ruby/core/process/uid_spec.rb b/spec/ruby/core/process/uid_spec.rb
index a068b1a2c1..1e218ef4fe 100644
--- a/spec/ruby/core/process/uid_spec.rb
+++ b/spec/ruby/core/process/uid_spec.rb
@@ -20,16 +20,16 @@ end
 describe "Process.uid=" do
   platform_is_not :windows do
     it "raises TypeError if not passed an Integer" do
-      -> { Process.uid = Object.new }.should raise_error(TypeError)
+      -> { Process.uid = Object.new }.should.raise(TypeError)
     end
 
     as_user do
       it "raises Errno::ERPERM if run by a non privileged user trying to set the superuser id" do
-        -> { (Process.uid = 0)}.should raise_error(Errno::EPERM)
+        -> { (Process.uid = 0)}.should.raise(Errno::EPERM)
       end
 
       it "raises Errno::ERPERM if run by a non privileged user trying to set the superuser id from username" do
-        -> { Process.uid = "root" }.should raise_error(Errno::EPERM)
+        -> { Process.uid = "root" }.should.raise(Errno::EPERM)
       end
     end
 
diff --git a/spec/ruby/core/process/wait2_spec.rb b/spec/ruby/core/process/wait2_spec.rb
index 6eb7fc6d06..5c57dd40fb 100644
--- a/spec/ruby/core/process/wait2_spec.rb
+++ b/spec/ruby/core/process/wait2_spec.rb
@@ -4,15 +4,15 @@ describe "Process.wait2" do
   before :all do
     # HACK: this kludge is temporarily necessary because some
     # misbehaving spec somewhere else does not clear processes
-    # Note: background processes are unavoidable with MJIT,
+    # Note: background processes are unavoidable with RJIT,
     # but we shouldn't reap them from Ruby-space
     begin
       Process.wait(-1, Process::WNOHANG)
       $stderr.puts "Leaked process before wait2 specs! Waiting for it"
       leaked = Process.waitall
       $stderr.puts "leaked before wait2 specs: #{leaked}" unless leaked.empty?
-      # Ruby-space should not see PIDs used by mjit
-      leaked.should be_empty
+      # Ruby-space should not see PIDs used by rjit
+      leaked.should.empty?
     rescue Errno::ECHILD # No child processes
     rescue NotImplementedError
     end
@@ -30,7 +30,16 @@ describe "Process.wait2" do
   end
 
   it "raises a StandardError if no child processes exist" do
-    -> { Process.wait2 }.should raise_error(Errno::ECHILD)
-    -> { Process.wait2 }.should raise_error(StandardError)
+    -> { Process.wait2 }.should.raise(Errno::ECHILD)
+    -> { Process.wait2 }.should.raise(StandardError)
+  end
+
+  it "returns nil if the child process is still running when given the WNOHANG flag" do
+    IO.popen(ruby_cmd('STDIN.getbyte'), "w") do |io|
+      pid, status = Process.wait2(io.pid, Process::WNOHANG)
+      pid.should == nil
+      status.should == nil
+      io.write('a')
+    end
   end
 end
diff --git a/spec/ruby/core/process/wait_spec.rb b/spec/ruby/core/process/wait_spec.rb
index f393a99e0f..0b2e715f65 100644
--- a/spec/ruby/core/process/wait_spec.rb
+++ b/spec/ruby/core/process/wait_spec.rb
@@ -7,15 +7,14 @@ describe "Process.wait" do
   before :all do
     begin
       leaked = Process.waitall
-      puts "leaked before wait specs: #{leaked}" unless leaked.empty?
-      # Ruby-space should not see PIDs used by mjit
-      leaked.should be_empty
+      # Ruby-space should not see PIDs used by rjit
+      raise "subprocesses leaked before wait specs: #{leaked}" unless leaked.empty?
     rescue NotImplementedError
     end
   end
 
   it "raises an Errno::ECHILD if there are no child processes" do
-    -> { Process.wait }.should raise_error(Errno::ECHILD)
+    -> { Process.wait }.should.raise(Errno::ECHILD)
   end
 
   platform_is_not :windows do
@@ -27,14 +26,14 @@ describe "Process.wait" do
     it "sets $? to a Process::Status" do
       pid = Process.spawn(ruby_cmd('exit'))
       Process.wait
-      $?.should be_kind_of(Process::Status)
+      $?.should.is_a?(Process::Status)
       $?.pid.should == pid
     end
 
     it "waits for any child process if no pid is given" do
       pid = Process.spawn(ruby_cmd('exit'))
       Process.wait.should == pid
-      -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
     end
 
     it "waits for a specific child if a pid is given" do
@@ -42,14 +41,14 @@ describe "Process.wait" do
       pid2 = Process.spawn(ruby_cmd('exit'))
       Process.wait(pid2).should == pid2
       Process.wait(pid1).should == pid1
-      -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
-      -> { Process.kill(0, pid2) }.should raise_error(Errno::ESRCH)
+      -> { Process.kill(0, pid1) }.should.raise(Errno::ESRCH)
+      -> { Process.kill(0, pid2) }.should.raise(Errno::ESRCH)
     end
 
     it "coerces the pid to an Integer" do
       pid1 = Process.spawn(ruby_cmd('exit'))
       Process.wait(mock_int(pid1)).should == pid1
-      -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
+      -> { Process.kill(0, pid1) }.should.raise(Errno::ESRCH)
     end
 
     # This spec is probably system-dependent.
@@ -72,7 +71,7 @@ describe "Process.wait" do
         sleep
       end
 
-      Process.wait(pid, Process::WNOHANG).should be_nil
+      Process.wait(pid, Process::WNOHANG).should == nil
 
       # wait for the child to setup its TERM handler
       write.close
@@ -86,7 +85,7 @@ describe "Process.wait" do
     it "always accepts flags=0" do
       pid = Process.spawn(ruby_cmd('exit'))
       Process.wait(-1, 0).should == pid
-      -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
     end
   end
 end
diff --git a/spec/ruby/core/process/waitall_spec.rb b/spec/ruby/core/process/waitall_spec.rb
index 6cf4e32bc9..a77873f553 100644
--- a/spec/ruby/core/process/waitall_spec.rb
+++ b/spec/ruby/core/process/waitall_spec.rb
@@ -13,7 +13,7 @@ describe "Process.waitall" do
   end
 
   it "takes no arguments" do
-    -> { Process.waitall(0) }.should raise_error(ArgumentError)
+    -> { Process.waitall(0) }.should.raise(ArgumentError)
   end
 
   platform_is_not :windows do
@@ -24,7 +24,7 @@ describe "Process.waitall" do
       pids << Process.fork { Process.exit! 0 }
       Process.waitall
       pids.each { |pid|
-        -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+        -> { Process.kill(0, pid) }.should.raise(Errno::ESRCH)
       }
     end
 
@@ -34,14 +34,14 @@ describe "Process.waitall" do
       pids << Process.fork { Process.exit! 1 }
       pids << Process.fork { Process.exit! 0 }
       a = Process.waitall
-      a.should be_kind_of(Array)
+      a.should.is_a?(Array)
       a.size.should == 3
       pids.each { |pid|
         pid_status = a.assoc(pid)
-        pid_status.should be_kind_of(Array)
+        pid_status.should.is_a?(Array)
         pid_status.size.should == 2
         pid_status.first.should == pid
-        pid_status.last.should be_kind_of(Process::Status)
+        pid_status.last.should.is_a?(Process::Status)
       }
     end
   end
diff --git a/spec/ruby/core/process/waitpid_spec.rb b/spec/ruby/core/process/waitpid_spec.rb
index f7cf1a45a8..a02147b663 100644
--- a/spec/ruby/core/process/waitpid_spec.rb
+++ b/spec/ruby/core/process/waitpid_spec.rb
@@ -2,7 +2,8 @@ require_relative '../../spec_helper'
 
 describe "Process.waitpid" do
   it "returns nil when the process has not yet completed and WNOHANG is specified" do
-    pid = spawn("sleep 5")
+    cmd = platform_is(:windows) ? "timeout" : "sleep"
+    pid = spawn("#{cmd} 5")
     begin
       Process.waitpid(pid, Process::WNOHANG).should == nil
       Process.kill("KILL", pid)
diff --git a/spec/ruby/core/process/warmup_spec.rb b/spec/ruby/core/process/warmup_spec.rb
new file mode 100644
index 0000000000..4530ae222c
--- /dev/null
+++ b/spec/ruby/core/process/warmup_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+
+describe "Process.warmup" do
+  # The behavior is entirely implementation specific.
+  # Other implementations are free to just make it a noop
+  it "is implemented" do
+    Process.warmup.should == true
+  end
+end
diff --git a/spec/ruby/core/queue/deq_spec.rb b/spec/ruby/core/queue/deq_spec.rb
index 9510978eac..a2784e6a63 100644
--- a/spec/ruby/core/queue/deq_spec.rb
+++ b/spec/ruby/core/queue/deq_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "Queue#deq" do
   it_behaves_like :queue_deq, :deq, -> { Queue.new }
 end
+
+describe "Queue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = Queue.new; q.push(1); q.deq(timeout: v) }
+end
diff --git a/spec/ruby/core/queue/freeze_spec.rb b/spec/ruby/core/queue/freeze_spec.rb
new file mode 100644
index 0000000000..ced2cc52dd
--- /dev/null
+++ b/spec/ruby/core/queue/freeze_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/queue/freeze'
+
+describe "Queue#freeze" do
+  it_behaves_like :queue_freeze, :freeze, -> { Queue.new }
+end
diff --git a/spec/ruby/core/queue/initialize_spec.rb b/spec/ruby/core/queue/initialize_spec.rb
new file mode 100644
index 0000000000..080e4d0abd
--- /dev/null
+++ b/spec/ruby/core/queue/initialize_spec.rb
@@ -0,0 +1,60 @@
+require_relative '../../spec_helper'
+
+describe "Queue#initialize" do
+  it "can be passed no arguments for an empty Queue" do
+    q = Queue.new
+    q.size.should == 0
+    q.should.empty?
+  end
+
+  it "is a private method" do
+    Queue.private_instance_methods.include?(:initialize).should == true
+  end
+
+  it "adds all elements of the passed Enumerable to self" do
+    q = Queue.new([1, 2, 3])
+    q.size.should == 3
+    q.should_not.empty?
+    q.pop.should == 1
+    q.pop.should == 2
+    q.pop.should == 3
+    q.should.empty?
+  end
+
+  describe "converts the given argument to an Array using #to_a" do
+    it "uses #to_a on the provided Enumerable" do
+      enumerable = MockObject.new('mock-enumerable')
+      enumerable.should_receive(:to_a).and_return([1, 2, 3])
+      q = Queue.new(enumerable)
+      q.size.should == 3
+      q.should_not.empty?
+      q.pop.should == 1
+      q.pop.should == 2
+      q.pop.should == 3
+      q.should.empty?
+    end
+
+    it "raises a TypeError if the given argument can't be converted to an Array" do
+      -> { Queue.new(42) }.should.raise(TypeError)
+      -> { Queue.new(:abc) }.should.raise(TypeError)
+    end
+
+    it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to an Array" do
+      enumerable = MockObject.new('mock-enumerable')
+      enumerable.should_receive(:to_a).and_raise(NoMethodError)
+      -> { Queue.new(enumerable) }.should.raise(NoMethodError)
+    end
+  end
+
+  it "raises TypeError if the provided Enumerable does not respond to #to_a" do
+    enumerable = MockObject.new('mock-enumerable')
+    -> { Queue.new(enumerable) }.should.raise(TypeError, "can't convert MockObject into Array")
+  end
+
+  it "raises TypeError if #to_a does not return Array" do
+    enumerable = MockObject.new('mock-enumerable')
+    enumerable.should_receive(:to_a).and_return("string")
+
+    -> { Queue.new(enumerable) }.should raise_consistent_error(TypeError, "can't convert MockObject into Array (MockObject#to_a gives String)")
+  end
+end
diff --git a/spec/ruby/core/queue/pop_spec.rb b/spec/ruby/core/queue/pop_spec.rb
index 1ce9231685..3dff7db242 100644
--- a/spec/ruby/core/queue/pop_spec.rb
+++ b/spec/ruby/core/queue/pop_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "Queue#pop" do
   it_behaves_like :queue_deq, :pop, -> { Queue.new }
 end
+
+describe "Queue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = Queue.new; q.push(1); q.pop(timeout: v) }
+end
diff --git a/spec/ruby/core/queue/shift_spec.rb b/spec/ruby/core/queue/shift_spec.rb
index f84058e1df..c105da74b2 100644
--- a/spec/ruby/core/queue/shift_spec.rb
+++ b/spec/ruby/core/queue/shift_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "Queue#shift" do
   it_behaves_like :queue_deq, :shift, -> { Queue.new }
 end
+
+describe "Queue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = Queue.new; q.push(1); q.shift(timeout: v) }
+end
diff --git a/spec/ruby/core/random/bytes_spec.rb b/spec/ruby/core/random/bytes_spec.rb
index 2caf18fbd0..c9be07cd3f 100644
--- a/spec/ruby/core/random/bytes_spec.rb
+++ b/spec/ruby/core/random/bytes_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'shared/bytes'
 
@@ -9,7 +9,6 @@ describe "Random#bytes" do
     Random.new(33).bytes(2).should == Random.new(33).bytes(2)
   end
 
-  # Should double check this is official spec
   it "returns the same numeric output for a given seed across all implementations and platforms" do
     rnd = Random.new(33)
     rnd.bytes(2).should == "\x14\\"
@@ -18,15 +17,13 @@ describe "Random#bytes" do
   end
 
   it "returns the same numeric output for a given huge seed across all implementations and platforms" do
-    rnd = Random.new(bignum_value ** 4)
+    rnd = Random.new(2 ** (63 * 4))
     rnd.bytes(2).should == "_\x91"
     rnd.bytes(1000) # skip some
     rnd.bytes(2).should == "\x17\x12"
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Random.bytes" do
-    it_behaves_like :random_bytes, :bytes, Random
-  end
+describe "Random.bytes" do
+  it_behaves_like :random_bytes, :bytes, Random
 end
diff --git a/spec/ruby/core/random/default_spec.rb b/spec/ruby/core/random/default_spec.rb
index 1d8b1ce5ee..9e4845986d 100644
--- a/spec/ruby/core/random/default_spec.rb
+++ b/spec/ruby/core/random/default_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 
 describe "Random::DEFAULT" do
-  it "returns a Random instance" do
-    Random::DEFAULT.should be_an_instance_of(Random)
+  it "is no longer defined" do
+    Random.should_not.const_defined?(:DEFAULT)
   end
 end
diff --git a/spec/ruby/core/random/new_seed_spec.rb b/spec/ruby/core/random/new_seed_spec.rb
index 4b34e871a2..b2741aaa31 100644
--- a/spec/ruby/core/random/new_seed_spec.rb
+++ b/spec/ruby/core/random/new_seed_spec.rb
@@ -1,8 +1,8 @@
 require_relative '../../spec_helper'
 
 describe "Random.new_seed" do
-  it "returns a Bignum" do
-    Random.new_seed.should be_an_instance_of(Bignum)
+  it "returns an Integer" do
+    Random.new_seed.should.instance_of?(Integer)
   end
 
   it "returns an arbitrary seed value each time" do
diff --git a/spec/ruby/core/random/new_spec.rb b/spec/ruby/core/random/new_spec.rb
index 07d7b439ca..e20d487137 100644
--- a/spec/ruby/core/random/new_spec.rb
+++ b/spec/ruby/core/random/new_spec.rb
@@ -1,16 +1,17 @@
+require_relative "../../spec_helper"
 describe "Random.new" do
   it "returns a new instance of Random" do
-    Random.new.should be_an_instance_of(Random)
+    Random.new.should.instance_of?(Random)
   end
 
   it "uses a random seed value if none is supplied" do
-    Random.new.seed.should be_an_instance_of(Bignum)
+    Random.new.seed.should.instance_of?(Integer)
   end
 
   it "returns Random instances initialized with different seeds" do
     first = Random.new
     second = Random.new
-    (0..20).map { first.rand } .should_not == (0..20).map { second.rand }
+    (0..20).map { first.rand }.should_not == (0..20).map { second.rand }
   end
 
   it "accepts an Integer seed value as an argument" do
@@ -32,6 +33,6 @@ describe "Random.new" do
   it "raises a RangeError if passed a Complex (with imaginary part) seed value as an argument" do
     -> do
       Random.new(Complex(20,2))
-    end.should raise_error(RangeError)
+    end.should.raise(RangeError)
   end
 end
diff --git a/spec/ruby/core/random/rand_spec.rb b/spec/ruby/core/random/rand_spec.rb
index d1a76e5dac..c882db6381 100644
--- a/spec/ruby/core/random/rand_spec.rb
+++ b/spec/ruby/core/random/rand_spec.rb
@@ -4,7 +4,6 @@ require_relative 'shared/rand'
 
 describe "Random.rand" do
   it_behaves_like :random_number, :rand, Random.new
-  it_behaves_like :random_number, :random_number, Random.new
   it_behaves_like :random_number, :rand, Random
 
   it "returns a Float >= 0 if no max argument is passed" do
@@ -46,13 +45,13 @@ describe "Random.rand" do
   it "coerces arguments to Integers with #to_int" do
     obj = mock_numeric('int')
     obj.should_receive(:to_int).and_return(99)
-    Random.rand(obj).should be_kind_of(Integer)
+    Random.rand(obj).should.is_a?(Integer)
   end
 end
 
 describe "Random#rand with Fixnum" do
   it "returns an Integer" do
-    Random.new.rand(20).should be_an_instance_of(Fixnum)
+    Random.new.rand(20).should.instance_of?(Integer)
   end
 
   it "returns a Fixnum greater than or equal to 0" do
@@ -83,20 +82,20 @@ describe "Random#rand with Fixnum" do
   it "raises an ArgumentError when the argument is 0" do
     -> do
       Random.new.rand(0)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the argument is negative" do
     -> do
       Random.new.rand(-12)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 end
 
 describe "Random#rand with Bignum" do
   it "typically returns a Bignum" do
     rnd = Random.new(1)
-    10.times.map{ rnd.rand(bignum_value*2) }.max.should be_an_instance_of(Bignum)
+    10.times.map{ rnd.rand(bignum_value*2) }.max.should.instance_of?(Integer)
   end
 
   it "returns a Bignum greater than or equal to 0" do
@@ -122,13 +121,13 @@ describe "Random#rand with Bignum" do
   it "raises an ArgumentError when the argument is negative" do
     -> do
       Random.new.rand(-bignum_value)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 end
 
 describe "Random#rand with Float" do
   it "returns a Float" do
-    Random.new.rand(20.43).should be_an_instance_of(Float)
+    Random.new.rand(20.43).should.instance_of?(Float)
   end
 
   it "returns a Float greater than or equal to 0.0" do
@@ -154,25 +153,25 @@ describe "Random#rand with Float" do
   it "raises an ArgumentError when the argument is negative" do
     -> do
       Random.new.rand(-1.234567)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 end
 
 describe "Random#rand with Range" do
   it "returns an element from the Range" do
-    Random.new.rand(20..43).should be_an_instance_of(Fixnum)
+    Random.new.rand(20..43).should.instance_of?(Integer)
   end
 
   it "supports custom object types" do
-    rand(RandomSpecs::CustomRangeInteger.new(1)..RandomSpecs::CustomRangeInteger.new(42)).should be_an_instance_of(RandomSpecs::CustomRangeInteger)
-    rand(RandomSpecs::CustomRangeFloat.new(1.0)..RandomSpecs::CustomRangeFloat.new(42.0)).should be_an_instance_of(RandomSpecs::CustomRangeFloat)
-    rand(Time.now..Time.now).should be_an_instance_of(Time)
+    rand(RandomSpecs::CustomRangeInteger.new(1)..RandomSpecs::CustomRangeInteger.new(42)).should.instance_of?(RandomSpecs::CustomRangeInteger)
+    rand(RandomSpecs::CustomRangeFloat.new(1.0)..RandomSpecs::CustomRangeFloat.new(42.0)).should.instance_of?(RandomSpecs::CustomRangeFloat)
+    rand(Time.now..Time.now).should.instance_of?(Time)
   end
 
   it "returns an object that is a member of the Range" do
     prng = Random.new
     r = 20..30
-    20.times { r.member?(prng.rand(r)).should be_true }
+    20.times { r.member?(prng.rand(r)).should == true }
   end
 
   it "works with inclusive ranges" do
@@ -202,25 +201,24 @@ describe "Random#rand with Range" do
   end
 
   it "considers Integers as Floats if one end point is a float" do
-    Random.new(42).rand(0.0..1).should be_kind_of(Float)
-    Random.new(42).rand(0..1.0).should be_kind_of(Float)
+    Random.new(42).rand(0.0..1).should.is_a?(Float)
+    Random.new(42).rand(0..1.0).should.is_a?(Float)
+  end
+
+  it "returns a float within a given float range" do
+    Random.new(42).rand(0.0...100.0).should == 37.454011884736246
+    Random.new(42).rand(-100.0...0.0).should == -62.545988115263754
   end
 
   it "raises an ArgumentError when the startpoint lacks #+ and #- methods" do
     -> do
       Random.new.rand(Object.new..67)
-    end.should raise_error(ArgumentError)
+    end.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the endpoint lacks #+ and #- methods" do
     -> do
       Random.new.rand(68..Object.new)
-    end.should raise_error(ArgumentError)
-  end
-end
-
-ruby_version_is "2.6" do
-  describe "Random.random_number" do
-    it_behaves_like :random_number, :random_number, Random
+    end.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/random/random_number_spec.rb b/spec/ruby/core/random/random_number_spec.rb
new file mode 100644
index 0000000000..bad81aeff6
--- /dev/null
+++ b/spec/ruby/core/random/random_number_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative 'shared/rand'
+
+describe "Random.random_number" do
+  it_behaves_like :random_number, :random_number, Random.new
+
+  it_behaves_like :random_number, :random_number, Random
+end
diff --git a/spec/ruby/core/random/raw_seed_spec.rb b/spec/ruby/core/random/raw_seed_spec.rb
deleted file mode 100644
index c1a1eb1f42..0000000000
--- a/spec/ruby/core/random/raw_seed_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-# -*- encoding: binary -*-
-require_relative '../../spec_helper'
-require_relative 'shared/urandom'
-
-ruby_version_is "2.5" do
-  describe "Random.urandom" do
-    it_behaves_like :random_urandom, :urandom
-  end
-end
diff --git a/spec/ruby/core/random/seed_spec.rb b/spec/ruby/core/random/seed_spec.rb
index bf4524fdd9..6529b2c873 100644
--- a/spec/ruby/core/random/seed_spec.rb
+++ b/spec/ruby/core/random/seed_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Random#seed" do
   it "returns an Integer" do
-    Random.new.seed.should be_kind_of(Integer)
+    Random.new.seed.should.is_a?(Integer)
   end
 
   it "returns an arbitrary seed if the constructor was called without arguments" do
diff --git a/spec/ruby/core/random/shared/bytes.rb b/spec/ruby/core/random/shared/bytes.rb
index 9afad3b7f8..86c64d5696 100644
--- a/spec/ruby/core/random/shared/bytes.rb
+++ b/spec/ruby/core/random/shared/bytes.rb
@@ -1,6 +1,6 @@
 describe :random_bytes, shared: true do
   it "returns a String" do
-    @object.send(@method, 1).should be_an_instance_of(String)
+    @object.send(@method, 1).should.instance_of?(String)
   end
 
   it "returns a String of the length given as argument" do
diff --git a/spec/ruby/core/random/shared/rand.rb b/spec/ruby/core/random/shared/rand.rb
index d3b24b8851..655c75c9f1 100644
--- a/spec/ruby/core/random/shared/rand.rb
+++ b/spec/ruby/core/random/shared/rand.rb
@@ -1,9 +1,9 @@
 describe :random_number, shared: true do
   it "returns a Float if no max argument is passed" do
-    @object.send(@method).should be_kind_of(Float)
+    @object.send(@method).should.is_a?(Float)
   end
 
   it "returns an Integer if an Integer argument is passed" do
-    @object.send(@method, 20).should be_kind_of(Integer)
+    @object.send(@method, 20).should.is_a?(Integer)
   end
 end
diff --git a/spec/ruby/core/random/shared/urandom.rb b/spec/ruby/core/random/shared/urandom.rb
deleted file mode 100644
index 159716075c..0000000000
--- a/spec/ruby/core/random/shared/urandom.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-describe :random_urandom, shared: true do
-  it "returns a String" do
-    Random.send(@method, 1).should be_an_instance_of(String)
-  end
-
-  it "returns a String of the length given as argument" do
-    Random.send(@method, 15).length.should == 15
-  end
-
-  it "raises an ArgumentError on a negative size" do
-    -> {
-      Random.send(@method, -1)
-    }.should raise_error(ArgumentError)
-  end
-
-  it "returns a binary String" do
-    Random.send(@method, 15).encoding.should == Encoding::BINARY
-  end
-
-  it "returns a random binary String" do
-    Random.send(@method, 12).should_not == Random.send(@method, 12)
-  end
-end
diff --git a/spec/ruby/core/random/urandom_spec.rb b/spec/ruby/core/random/urandom_spec.rb
index e27f83cdcd..94e9423a06 100644
--- a/spec/ruby/core/random/urandom_spec.rb
+++ b/spec/ruby/core/random/urandom_spec.rb
@@ -1,9 +1,25 @@
-# -*- encoding: binary -*-
 require_relative '../../spec_helper'
-require_relative 'shared/urandom'
 
-ruby_version_is ""..."2.5" do
-  describe "Random.raw_seed" do
-    it_behaves_like :random_urandom, :raw_seed
+describe "Random.urandom" do
+  it "returns a String" do
+    Random.urandom(1).should.instance_of?(String)
+  end
+
+  it "returns a String of the length given as argument" do
+    Random.urandom(15).length.should == 15
+  end
+
+  it "raises an ArgumentError on a negative size" do
+    -> {
+      Random.urandom(-1)
+    }.should.raise(ArgumentError)
+  end
+
+  it "returns a binary String" do
+    Random.urandom(15).encoding.should == Encoding::BINARY
+  end
+
+  it "returns a random binary String" do
+    Random.urandom(12).should_not == Random.urandom(12)
   end
 end
diff --git a/spec/ruby/core/range/bsearch_spec.rb b/spec/ruby/core/range/bsearch_spec.rb
index 009cafb00e..151a1798cf 100644
--- a/spec/ruby/core/range/bsearch_spec.rb
+++ b/spec/ruby/core/range/bsearch_spec.rb
@@ -3,38 +3,46 @@ require_relative '../enumerable/shared/enumeratorized'
 
 describe "Range#bsearch" do
   it "returns an Enumerator when not passed a block" do
-    (0..1).bsearch.should be_an_instance_of(Enumerator)
+    (0..1).bsearch.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :enumeratorized_with_unknown_size, :bsearch, (1..3)
 
   it "raises a TypeError if the block returns an Object" do
-    -> { (0..1).bsearch { Object.new } }.should raise_error(TypeError)
+    -> { (0..1).bsearch { Object.new } }.should.raise(TypeError, "wrong argument type Object (must be numeric, true, false or nil)")
   end
 
-  it "raises a TypeError if the block returns a String" do
-    -> { (0..1).bsearch { "1" } }.should raise_error(TypeError)
+  it "raises a TypeError if the block returns a String and boundaries are Integer values" do
+    -> { (0..1).bsearch { "1" } }.should.raise(TypeError, "wrong argument type String (must be numeric, true, false or nil)")
+  end
+
+  it "raises a TypeError if the block returns a String and boundaries are Float values" do
+    -> { (0.0..1.0).bsearch { "1" } }.should.raise(TypeError, "wrong argument type String (must be numeric, true, false or nil)")
   end
 
   it "raises a TypeError if the Range has Object values" do
     value = mock("range bsearch")
     r = Range.new value, value
 
-    -> { r.bsearch { true } }.should raise_error(TypeError)
+    -> { r.bsearch { true } }.should.raise(TypeError, "can't do binary search for MockObject")
   end
 
   it "raises a TypeError if the Range has String values" do
-    -> { ("a".."e").bsearch { true } }.should raise_error(TypeError)
+    -> { ("a".."e").bsearch { true } }.should.raise(TypeError, "can't do binary search for String")
+  end
+
+  it "raises TypeError when non-Numeric begin/end and block not passed" do
+    -> { ("a".."e").bsearch }.should.raise(TypeError, "can't do binary search for String")
   end
 
   context "with Integer values" do
     context "with a block returning true or false" do
       it "returns nil if the block returns false for every element" do
-        (0...3).bsearch { |x| x > 3 }.should be_nil
+        (0...3).bsearch { |x| x > 3 }.should == nil
       end
 
       it "returns nil if the block returns nil for every element" do
-        (0..3).bsearch { |x| nil }.should be_nil
+        (0..3).bsearch { |x| nil }.should == nil
       end
 
       it "returns minimum element if the block returns true for every element" do
@@ -54,21 +62,21 @@ describe "Range#bsearch" do
 
     context "with a block returning negative, zero, positive numbers" do
       it "returns nil if the block returns less than zero for every element" do
-        (0..3).bsearch { |x| x <=> 5 }.should be_nil
+        (0..3).bsearch { |x| x <=> 5 }.should == nil
       end
 
       it "returns nil if the block returns greater than zero for every element" do
-        (0..3).bsearch { |x| x <=> -1 }.should be_nil
+        (0..3).bsearch { |x| x <=> -1 }.should == nil
 
       end
 
       it "returns nil if the block never returns zero" do
-        (0..3).bsearch { |x| x < 2 ? 1 : -1 }.should be_nil
+        (0..3).bsearch { |x| x < 2 ? 1 : -1 }.should == nil
       end
 
       it "accepts (+/-)Float::INFINITY from the block" do
-        (0..4).bsearch { |x| Float::INFINITY }.should be_nil
-        (0..4).bsearch { |x| -Float::INFINITY }.should be_nil
+        (0..4).bsearch { |x| Float::INFINITY }.should == nil
+        (0..4).bsearch { |x| -Float::INFINITY }.should == nil
       end
 
       it "returns an element at an index for which block returns 0.0" do
@@ -78,48 +86,97 @@ describe "Range#bsearch" do
 
       it "returns an element at an index for which block returns 0" do
         result = (0..4).bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
-        [1, 2].should include(result)
+        [1, 2].should.include?(result)
       end
     end
+
+    it "returns nil for empty ranges" do
+      (0...0).bsearch { true }.should == nil
+      (0...0).bsearch { false }.should == nil
+      (0...0).bsearch { 1 }.should == nil
+      (0...0).bsearch { 0 }.should == nil
+      (0...0).bsearch { -1 }.should == nil
+
+      (4..2).bsearch { true }.should == nil
+      (4..2).bsearch { 1 }.should == nil
+      (4..2).bsearch { 0 }.should == nil
+      (4..2).bsearch { -1 }.should == nil
+    end
+
+    it "returns enumerator when block not passed" do
+      (0...3).bsearch.kind_of?(Enumerator).should == true
+    end
   end
 
   context "with Float values" do
     context "with a block returning true or false" do
       it "returns nil if the block returns false for every element" do
-        (0.1...2.3).bsearch { |x| x > 3 }.should be_nil
+        (0.1...2.3).bsearch { |x| x > 3 }.should == nil
       end
 
       it "returns nil if the block returns nil for every element" do
-        (-0.0..2.3).bsearch { |x| nil }.should be_nil
+        (-0.0..2.3).bsearch { |x| nil }.should == nil
       end
 
       it "returns minimum element if the block returns true for every element" do
-        (-0.2..4.8).bsearch { |x| x < 4 }.should == -0.2
+        (-0.2..4.8).bsearch { |x| x < 5 }.should == -0.2
       end
 
       it "returns the smallest element for which block returns true" do
         (0..4.2).bsearch { |x| x >= 2 }.should == 2
         (-1.2..4.3).bsearch { |x| x >= 1 }.should == 1
       end
+
+      it "returns a boundary element if appropriate" do
+        (1.0..3.0).bsearch { |x| x >= 3.0 }.should == 3.0
+        (1.0...3.0).bsearch { |x| x >= 3.0.prev_float }.should == 3.0.prev_float
+        (1.0..3.0).bsearch { |x| x >= 1.0 }.should == 1.0
+        (1.0...3.0).bsearch { |x| x >= 1.0 }.should == 1.0
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        (0..inf).bsearch { |x| x == inf }.should == inf
+        (0...inf).bsearch { |x| x == inf }.should == nil
+        (-inf..0).bsearch { |x| x != -inf }.should == -Float::MAX
+        (-inf...0).bsearch { |x| x != -inf }.should == -Float::MAX
+        (inf..inf).bsearch { |x| true }.should == inf
+        (inf...inf).bsearch { |x| true }.should == nil
+        (-inf..-inf).bsearch { |x| true }.should == -inf
+        (-inf...-inf).bsearch { |x| true }.should == nil
+        (inf..0).bsearch { true }.should == nil
+        (inf...0).bsearch { true }.should == nil
+        (0..-inf).bsearch { true }.should == nil
+        (0...-inf).bsearch { true }.should == nil
+        (inf..-inf).bsearch { true }.should == nil
+        (inf...-inf).bsearch { true }.should == nil
+        (0..inf).bsearch { |x| x >= 3 }.should == 3.0
+        (0...inf).bsearch { |x| x >= 3 }.should == 3.0
+        (-inf..0).bsearch { |x| x >= -3 }.should == -3.0
+        (-inf...0).bsearch { |x| x >= -3 }.should == -3.0
+        (-inf..inf).bsearch { |x| x >= 3 }.should == 3.0
+        (-inf...inf).bsearch { |x| x >= 3 }.should == 3.0
+        (0..inf).bsearch { |x| x >= Float::MAX }.should == Float::MAX
+        (0...inf).bsearch { |x| x >= Float::MAX }.should == Float::MAX
+      end
     end
 
     context "with a block returning negative, zero, positive numbers" do
       it "returns nil if the block returns less than zero for every element" do
-        (-2.0..3.2).bsearch { |x| x <=> 5 }.should be_nil
+        (-2.0..3.2).bsearch { |x| x <=> 5 }.should == nil
       end
 
       it "returns nil if the block returns greater than zero for every element" do
-        (0.3..3.0).bsearch { |x| x <=> -1 }.should be_nil
-
+        (0.3..3.0).bsearch { |x| x <=> -1 }.should == nil
       end
 
       it "returns nil if the block never returns zero" do
-        (0.2..2.3).bsearch { |x| x < 2 ? 1 : -1 }.should be_nil
+        (0.2..2.3).bsearch { |x| x < 2 ? 1 : -1 }.should == nil
       end
 
       it "accepts (+/-)Float::INFINITY from the block" do
-        (0.1..4.5).bsearch { |x| Float::INFINITY }.should be_nil
-        (-5.0..4.0).bsearch { |x| -Float::INFINITY }.should be_nil
+        (0.1..4.5).bsearch { |x| Float::INFINITY }.should == nil
+        (-5.0..4.0).bsearch { |x| -Float::INFINITY }.should == nil
       end
 
       it "returns an element at an index for which block returns 0.0" do
@@ -130,8 +187,280 @@ describe "Range#bsearch" do
       it "returns an element at an index for which block returns 0" do
         result = (0.1..4.9).bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
         result.should >= 1
-        result.should <= 2
+        result.should <= 3
+      end
+
+      it "returns an element at an index for which block returns 0 (small numbers)" do
+        result = (0.1..0.3).bsearch { |x| x < 0.1 ? 1 : x > 0.3 ? -1 : 0 }
+        result.should >= 0.1
+        result.should <= 0.3
+      end
+
+      it "returns a boundary element if appropriate" do
+        (1.0..3.0).bsearch { |x| 3.0 - x }.should == 3.0
+        (1.0...3.0).bsearch { |x| 3.0.prev_float - x }.should == 3.0.prev_float
+        (1.0..3.0).bsearch { |x| 1.0 - x }.should == 1.0
+        (1.0...3.0).bsearch { |x| 1.0 - x }.should == 1.0
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        (0..inf).bsearch { |x| x == inf ? 0 : 1 }.should == inf
+        (0...inf).bsearch { |x| x == inf ? 0 : 1 }.should == nil
+        (-inf...0).bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        (-inf..0).bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        (inf..inf).bsearch { 0 }.should == inf
+        (inf...inf).bsearch { 0 }.should == nil
+        (-inf..-inf).bsearch { 0 }.should == -inf
+        (-inf...-inf).bsearch { 0 }.should == nil
+        (inf..0).bsearch { 0 }.should == nil
+        (inf...0).bsearch { 0 }.should == nil
+        (0..-inf).bsearch { 0 }.should == nil
+        (0...-inf).bsearch { 0 }.should == nil
+        (inf..-inf).bsearch { 0 }.should == nil
+        (inf...-inf).bsearch { 0 }.should == nil
+        (-inf..inf).bsearch { |x| 3 - x }.should == 3.0
+        (-inf...inf).bsearch { |x| 3 - x }.should == 3.0
+        (0...inf).bsearch { |x| x >= Float::MAX ? 0 : 1 }.should == Float::MAX
       end
     end
+
+    it "returns enumerator when block not passed" do
+      (0.1...2.3).bsearch.kind_of?(Enumerator).should == true
+    end
+  end
+
+  context "with endless ranges and Integer values" do
+    context "with a block returning true or false" do
+      it "returns minimum element if the block returns true for every element" do
+        eval("(-2..)").bsearch { |x| true }.should == -2
+      end
+
+      it "returns the smallest element for which block returns true" do
+        eval("(0..)").bsearch { |x| x >= 2 }.should == 2
+        eval("(-1..)").bsearch { |x| x >= 1 }.should == 1
+      end
+    end
+
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns less than zero for every element" do
+        eval("(0..)").bsearch { |x| -1 }.should == nil
+      end
+
+      it "returns nil if the block never returns zero" do
+        eval("(0..)").bsearch { |x| x > 5 ? -1 : 1 }.should == nil
+      end
+
+      it "accepts -Float::INFINITY from the block" do
+        eval("(0..)").bsearch { |x| -Float::INFINITY }.should == nil
+      end
+
+      it "returns an element at an index for which block returns 0.0" do
+        result = eval("(0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
+
+      it "returns an element at an index for which block returns 0" do
+        result = eval("(0..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        [1, 2, 3].should.include?(result)
+      end
+    end
+
+    it "returns enumerator when block not passed" do
+      eval("(-2..)").bsearch.kind_of?(Enumerator).should == true
+    end
+  end
+
+  context "with endless ranges and Float values" do
+    context "with a block returning true or false" do
+      it "returns nil if the block returns false for every element" do
+        eval("(0.1..)").bsearch { |x| x < 0.0 }.should == nil
+        eval("(0.1...)").bsearch { |x| x < 0.0 }.should == nil
+      end
+
+      it "returns nil if the block returns nil for every element" do
+        eval("(-0.0..)").bsearch { |x| nil }.should == nil
+        eval("(-0.0...)").bsearch { |x| nil }.should == nil
+      end
+
+      it "returns minimum element if the block returns true for every element" do
+        eval("(-0.2..)").bsearch { |x| true }.should == -0.2
+        eval("(-0.2...)").bsearch { |x| true }.should == -0.2
+      end
+
+      it "returns the smallest element for which block returns true" do
+        eval("(0..)").bsearch { |x| x >= 2 }.should == 2
+        eval("(-1.2..)").bsearch { |x| x >= 1 }.should == 1
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        eval("(inf..)").bsearch { |x| true }.should == inf
+        eval("(inf...)").bsearch { |x| true }.should == nil
+        eval("(-inf..)").bsearch { |x| true }.should == -inf
+        eval("(-inf...)").bsearch { |x| true }.should == -inf
+      end
+    end
+
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns less than zero for every element" do
+        eval("(-2.0..)").bsearch { |x| -1 }.should == nil
+        eval("(-2.0...)").bsearch { |x| -1 }.should == nil
+      end
+
+      it "returns nil if the block returns greater than zero for every element" do
+        eval("(0.3..)").bsearch { |x| 1 }.should == nil
+        eval("(0.3...)").bsearch { |x| 1 }.should == nil
+      end
+
+      it "returns nil if the block never returns zero" do
+        eval("(0.2..)").bsearch { |x| x < 2 ? 1 : -1 }.should == nil
+      end
+
+      it "accepts (+/-)Float::INFINITY from the block" do
+        eval("(0.1..)").bsearch { |x| Float::INFINITY }.should == nil
+        eval("(-5.0..)").bsearch { |x| -Float::INFINITY }.should == nil
+      end
+
+      it "returns an element at an index for which block returns 0.0" do
+        result = eval("(0.0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
+
+      it "returns an element at an index for which block returns 0" do
+        result = eval("(0.1..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        result.should >= 1
+        result.should <= 3
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        eval("(inf..)").bsearch { |x| 1 }.should == nil
+        eval("(inf...)").bsearch { |x| 1 }.should == nil
+        eval("(inf..)").bsearch { |x| x == inf ? 0 : 1 }.should == inf
+        eval("(inf...)").bsearch { |x| x == inf ? 0 : 1 }.should == nil
+        eval("(-inf..)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        eval("(-inf...)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        eval("(-inf..)").bsearch { |x| 3 - x }.should == 3
+        eval("(-inf...)").bsearch { |x| 3 - x }.should == 3
+        eval("(0.0...)").bsearch { 0 }.should != inf
+      end
+    end
+
+    it "returns enumerator when block not passed" do
+      eval("(0.1..)").bsearch.kind_of?(Enumerator).should == true
+    end
+  end
+
+  context "with beginless ranges and Integer values" do
+    context "with a block returning true or false" do
+      it "returns the smallest element for which block returns true" do
+        (..10).bsearch { |x| x >= 2 }.should == 2
+        (...-1).bsearch { |x| x >= -10 }.should == -10
+      end
+    end
+
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns greater than zero for every element" do
+        (..0).bsearch { |x| 1 }.should == nil
+      end
+
+      it "returns nil if the block never returns zero" do
+        (..0).bsearch { |x| x > 5 ? -1 : 1 }.should == nil
+      end
+
+      it "accepts Float::INFINITY from the block" do
+        (..0).bsearch { |x| Float::INFINITY }.should == nil
+      end
+
+      it "returns an element at an index for which block returns 0.0" do
+        result = (..10).bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
+
+      it "returns an element at an index for which block returns 0" do
+        result = (...10).bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        [1, 2, 3].should.include?(result)
+      end
+    end
+
+    it "returns enumerator when block not passed" do
+      (..10).bsearch.kind_of?(Enumerator).should == true
+    end
+  end
+
+  context "with beginless ranges and Float values" do
+    context "with a block returning true or false" do
+      it "returns nil if the block returns true for every element" do
+        (..-0.1).bsearch { |x| x > 0.0 }.should == nil
+        (...-0.1).bsearch { |x| x > 0.0 }.should == nil
+      end
+
+      it "returns nil if the block returns nil for every element" do
+        (..-0.1).bsearch { |x| nil }.should == nil
+        (...-0.1).bsearch { |x| nil }.should == nil
+      end
+
+      it "returns the smallest element for which block returns true" do
+        (..10).bsearch { |x| x >= 2 }.should == 2
+        (..10).bsearch { |x| x >= 1 }.should == 1
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        (..inf).bsearch { |x| true }.should == -inf
+        (...inf).bsearch { |x| true }.should == -inf
+        (..-inf).bsearch { |x| true }.should == -inf
+        (...-inf).bsearch { |x| true }.should == nil
+      end
+    end
+
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns less than zero for every element" do
+        (..5.0).bsearch { |x| -1 }.should == nil
+        (...5.0).bsearch { |x| -1 }.should == nil
+      end
+
+      it "returns nil if the block returns greater than zero for every element" do
+        (..1.1).bsearch { |x| 1 }.should == nil
+        (...1.1).bsearch { |x| 1 }.should == nil
+      end
+
+      it "returns nil if the block never returns zero" do
+        (..6.3).bsearch { |x| x < 2 ? 1 : -1 }.should == nil
+      end
+
+      it "accepts (+/-)Float::INFINITY from the block" do
+        (..5.0).bsearch { |x| Float::INFINITY }.should == nil
+        (..7.0).bsearch { |x| -Float::INFINITY }.should == nil
+      end
+
+      it "returns an element at an index for which block returns 0.0" do
+        result = (..8.0).bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
+
+      it "returns an element at an index for which block returns 0" do
+        result = (..8.0).bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        result.should >= 1
+        result.should <= 3
+      end
+
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        (..-inf).bsearch { |x| 1 }.should == nil
+        (...-inf).bsearch { |x| 1 }.should == nil
+        (..inf).bsearch { |x| x == inf ? 0 : 1 }.should == inf
+        (...inf).bsearch { |x| x == inf ? 0 : 1 }.should == nil
+        (..-inf).bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        (...-inf).bsearch { |x| x == -inf ? 0 : -1 }.should == nil
+        (..inf).bsearch { |x| 3 - x }.should == 3
+        (...inf).bsearch { |x| 3 - x }.should == 3
+      end
+    end
+
+    it "returns enumerator when block not passed" do
+      (..-0.1).bsearch.kind_of?(Enumerator).should == true
+    end
   end
 end
diff --git a/spec/ruby/core/range/case_compare_spec.rb b/spec/ruby/core/range/case_compare_spec.rb
index 0ca03f6a35..7a76487d68 100644
--- a/spec/ruby/core/range/case_compare_spec.rb
+++ b/spec/ruby/core/range/case_compare_spec.rb
@@ -3,26 +3,15 @@ require_relative 'shared/cover_and_include'
 require_relative 'shared/cover'
 
 describe "Range#===" do
-  ruby_version_is ""..."2.6" do
-    it "returns the result of calling #include? on self" do
-      range = 0...10
-      range.should_receive(:include?).with(2).and_return(:true)
-      (range === 2).should == :true
-    end
-
-    it "requires #succ method to be implemented" do
-      range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
-
-      -> do
-        range === RangeSpecs::WithoutSucc.new(2)
-      end.should raise_error(TypeError, /can't iterate from/)
-    end
+  it "returns the result of calling #cover? on self" do
+    range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
+    (range === RangeSpecs::WithoutSucc.new(2)).should == true
   end
 
-  ruby_version_is "2.6" do
-    it "returns the result of calling #cover? on self" do
-      range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
-      (range === RangeSpecs::WithoutSucc.new(2)).should == true
-    end
+  it_behaves_like :range_cover_and_include, :===
+  it_behaves_like :range_cover, :===
+
+  it "returns true on any value if begin and end are both nil" do
+    (nil..nil).should === 1
   end
 end
diff --git a/spec/ruby/core/range/clone_spec.rb b/spec/ruby/core/range/clone_spec.rb
new file mode 100644
index 0000000000..cf6ce74da0
--- /dev/null
+++ b/spec/ruby/core/range/clone_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Range#clone" do
+  it "duplicates the range" do
+    original = (1..3)
+    copy = original.clone
+    copy.begin.should == 1
+    copy.end.should == 3
+    copy.should_not.exclude_end?
+    copy.should_not.equal? original
+
+    original = ("a"..."z")
+    copy = original.clone
+    copy.begin.should == "a"
+    copy.end.should == "z"
+    copy.should.exclude_end?
+    copy.should_not.equal? original
+  end
+
+  it "maintains the frozen state" do
+    (1..2).clone.frozen?.should == (1..2).frozen?
+    (1..).clone.frozen?.should == (1..).frozen?
+    Range.new(1, 2).clone.frozen?.should == Range.new(1, 2).frozen?
+    Class.new(Range).new(1, 2).clone.frozen?.should == Class.new(Range).new(1, 2).frozen?
+  end
+end
diff --git a/spec/ruby/core/range/count_spec.rb b/spec/ruby/core/range/count_spec.rb
new file mode 100644
index 0000000000..24d4a9caf3
--- /dev/null
+++ b/spec/ruby/core/range/count_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+
+describe "Range#count" do
+  it "returns Infinity for beginless ranges without arguments or blocks" do
+    inf = Float::INFINITY
+    eval("('a'...)").count.should == inf
+    eval("(7..)").count.should == inf
+    (...'a').count.should == inf
+    (...nil).count.should == inf
+    (..10.0).count.should == inf
+  end
+end
diff --git a/spec/ruby/core/range/cover_spec.rb b/spec/ruby/core/range/cover_spec.rb
index 29c0e0bfa8..eb8d5453bf 100644
--- a/spec/ruby/core/range/cover_spec.rb
+++ b/spec/ruby/core/range/cover_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'shared/cover_and_include'
 require_relative 'shared/cover'
@@ -6,4 +6,9 @@ require_relative 'shared/cover'
 describe "Range#cover?" do
   it_behaves_like :range_cover_and_include, :cover?
   it_behaves_like :range_cover, :cover?
+  it_behaves_like :range_cover_subrange, :cover?
+
+  it "covers U+9995 in the range U+0999..U+9999" do
+    ("\u{999}".."\u{9999}").cover?("\u{9995}").should == true
+  end
 end
diff --git a/spec/ruby/core/range/dup_spec.rb b/spec/ruby/core/range/dup_spec.rb
index d1c029c6b7..fab3c3f1b2 100644
--- a/spec/ruby/core/range/dup_spec.rb
+++ b/spec/ruby/core/range/dup_spec.rb
@@ -2,14 +2,22 @@ require_relative '../../spec_helper'
 
 describe "Range#dup" do
   it "duplicates the range" do
-    copy = (1..3).dup
+    original = (1..3)
+    copy = original.dup
     copy.begin.should == 1
     copy.end.should == 3
-    copy.exclude_end?.should == false
+    copy.should_not.exclude_end?
+    copy.should_not.equal?(original)
 
     copy = ("a"..."z").dup
     copy.begin.should == "a"
     copy.end.should == "z"
-    copy.exclude_end?.should == true
+    copy.should.exclude_end?
+  end
+
+  it "creates an unfrozen range" do
+    (1..2).dup.should_not.frozen?
+    (1..).dup.should_not.frozen?
+    Range.new(1, 2).dup.should_not.frozen?
   end
 end
diff --git a/spec/ruby/core/range/each_spec.rb b/spec/ruby/core/range/each_spec.rb
index 110b0602d0..b4389f864d 100644
--- a/spec/ruby/core/range/each_spec.rb
+++ b/spec/ruby/core/range/each_spec.rb
@@ -32,29 +32,64 @@ describe "Range#each" do
     a.should == [x, y]
   end
 
+  it "works for non-ASCII ranges" do
+    a = []
+    ('Σ'..'Ω').each { |i| a << i }
+    a.should == ["Σ", "Τ", "Υ", "Φ", "Χ", "Ψ", "Ω"]
+  end
+
+  it "works with endless ranges" do
+    a = []
+    (-2..).each { |x| break if x > 2; a << x }
+    a.should == [-2, -1, 0, 1, 2]
+
+    a = []
+    (-2...).each { |x| break if x > 2; a << x }
+    a.should == [-2, -1, 0, 1, 2]
+  end
+
+  it "works with String endless ranges" do
+    a = []
+    ('A'..).each { |x| break if x > "D"; a << x }
+    a.should == ["A", "B", "C", "D"]
+
+    a = []
+    ('A'...).each { |x| break if x > "D"; a << x }
+    a.should == ["A", "B", "C", "D"]
+  end
+
+  it "raises a TypeError beginless ranges" do
+    -> { (..2).each { |x| x } }.should.raise(TypeError)
+  end
+
   it "raises a TypeError if the first element does not respond to #succ" do
-    -> { (0.5..2.4).each { |i| i } }.should raise_error(TypeError)
+    -> { (0.5..2.4).each { |i| i } }.should.raise(TypeError)
 
     b = mock('x')
     (a = mock('1')).should_receive(:<=>).with(b).and_return(1)
 
-    -> { (a..b).each { |i| i } }.should raise_error(TypeError)
+    -> { (a..b).each { |i| i } }.should.raise(TypeError)
   end
 
   it "returns self" do
     range = 1..10
-    range.each{}.should equal(range)
+    range.each{}.should.equal?(range)
   end
 
   it "returns an enumerator when no block given" do
     enum = (1..3).each
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == [1, 2, 3]
   end
 
-  it "raises a TypeError if the first element is a Time object" do
-    t = Time.now
-    -> { (t..t+1).each { |i| i } }.should raise_error(TypeError)
+  it "supports Time objects that respond to #succ" do
+    t = Time.utc(1970)
+    def t.succ; self + 1 end
+    t_succ = t.succ
+    def t_succ.succ; self + 1; end
+
+    (t..t_succ).to_a.should == [Time.utc(1970), Time.utc(1970, nil, nil, nil, nil, 1)]
+    (t...t_succ).to_a.should == [Time.utc(1970)]
   end
 
   it "passes each Symbol element by using #succ" do
diff --git a/spec/ruby/core/range/eql_spec.rb b/spec/ruby/core/range/eql_spec.rb
index fa6c71840e..cdc19c9331 100644
--- a/spec/ruby/core/range/eql_spec.rb
+++ b/spec/ruby/core/range/eql_spec.rb
@@ -5,6 +5,6 @@ describe "Range#eql?" do
   it_behaves_like :range_eql, :eql?
 
   it "returns false if the endpoints are not eql?" do
-    (0..1).should_not eql(0..1.0)
+    (0..1).should_not.eql?(0..1.0)
   end
 end
diff --git a/spec/ruby/core/range/equal_value_spec.rb b/spec/ruby/core/range/equal_value_spec.rb
index 889557fc2a..83dcf5cec8 100644
--- a/spec/ruby/core/range/equal_value_spec.rb
+++ b/spec/ruby/core/range/equal_value_spec.rb
@@ -7,4 +7,12 @@ describe "Range#==" do
   it "returns true if the endpoints are ==" do
     (0..1).should == (0..1.0)
   end
+
+  it "returns true if the endpoints are == for endless ranges" do
+    eval("(1.0..)").should == eval("(1.0..)")
+  end
+
+  it "returns true if the endpoints are == for beginless ranges" do
+    (...10).should == (...10)
+  end
 end
diff --git a/spec/ruby/core/range/exclude_end_spec.rb b/spec/ruby/core/range/exclude_end_spec.rb
index a209603d18..c4006fea78 100644
--- a/spec/ruby/core/range/exclude_end_spec.rb
+++ b/spec/ruby/core/range/exclude_end_spec.rb
@@ -2,18 +2,18 @@ require_relative '../../spec_helper'
 
 describe "Range#exclude_end?" do
   it "returns false if the range does not exclude the end value" do
-    (-2..2).exclude_end?.should == false
-    ('A'..'B').exclude_end?.should == false
-    (0.5..2.4).exclude_end?.should == false
-    (0xfffd..0xffff).exclude_end?.should == false
-    Range.new(0, 1).exclude_end?.should == false
+    (-2..2).should_not.exclude_end?
+    ('A'..'B').should_not.exclude_end?
+    (0.5..2.4).should_not.exclude_end?
+    (0xfffd..0xffff).should_not.exclude_end?
+    Range.new(0, 1).should_not.exclude_end?
   end
 
   it "returns true if the range excludes the end value" do
-    (0...5).exclude_end?.should == true
-    ('A'...'B').exclude_end?.should == true
-    (0.5...2.4).exclude_end?.should == true
-    (0xfffd...0xffff).exclude_end?.should == true
-    Range.new(0, 1, true).exclude_end?.should == true
+    (0...5).should.exclude_end?
+    ('A'...'B').should.exclude_end?
+    (0.5...2.4).should.exclude_end?
+    (0xfffd...0xffff).should.exclude_end?
+    Range.new(0, 1, true).should.exclude_end?
   end
 end
diff --git a/spec/ruby/core/range/first_spec.rb b/spec/ruby/core/range/first_spec.rb
index 5f073b48ee..54bd73a4e8 100644
--- a/spec/ruby/core/range/first_spec.rb
+++ b/spec/ruby/core/range/first_spec.rb
@@ -21,7 +21,7 @@ describe "Range#first" do
   end
 
   it "raises an ArgumentError when count is negative" do
-    -> { (0..2).first(-1) }.should raise_error(ArgumentError)
+    -> { (0..2).first(-1) }.should.raise(ArgumentError)
   end
 
   it "calls #to_int to convert the argument" do
@@ -32,7 +32,7 @@ describe "Range#first" do
   it "raises a TypeError if #to_int does not return an Integer" do
     obj = mock("to_int")
     obj.should_receive(:to_int).and_return("1")
-    -> { (2..3).first(obj) }.should raise_error(TypeError)
+    -> { (2..3).first(obj) }.should.raise(TypeError)
   end
 
   it "truncates the value when passed a Float" do
@@ -40,10 +40,14 @@ describe "Range#first" do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { (2..3).first(nil) }.should raise_error(TypeError)
+    -> { (2..3).first(nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { (2..3).first("1") }.should raise_error(TypeError)
+    -> { (2..3).first("1") }.should.raise(TypeError)
+  end
+
+  it "raises a RangeError when called on an beginless range" do
+    -> { (..1).first }.should.raise(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/frozen_spec.rb b/spec/ruby/core/range/frozen_spec.rb
new file mode 100644
index 0000000000..8dab5e5339
--- /dev/null
+++ b/spec/ruby/core/range/frozen_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../spec_helper'
+
+# There is no Range#frozen? method but this feels like the best place for these specs
+describe "Range#frozen?" do
+  it "is true for literal ranges" do
+    (1..2).should.frozen?
+    (1..).should.frozen?
+    (..1).should.frozen?
+  end
+
+  it "is true for Range.new" do
+    Range.new(1, 2).should.frozen?
+    Range.new(1, nil).should.frozen?
+    Range.new(nil, 1).should.frozen?
+  end
+
+  it "is false for instances of a subclass of Range" do
+    sub_range = Class.new(Range).new(1, 2)
+    sub_range.should_not.frozen?
+  end
+
+  it "is false for Range.allocate" do
+    Range.allocate.should_not.frozen?
+  end
+end
diff --git a/spec/ruby/core/range/hash_spec.rb b/spec/ruby/core/range/hash_spec.rb
index 90aeee7890..087f5d6de8 100644
--- a/spec/ruby/core/range/hash_spec.rb
+++ b/spec/ruby/core/range/hash_spec.rb
@@ -14,11 +14,11 @@ describe "Range#hash" do
     (0..10).hash.should_not == (0...10).hash
   end
 
-  it "generates a Fixnum for the hash value" do
-    (0..0).hash.should be_an_instance_of(Fixnum)
-    (0..1).hash.should be_an_instance_of(Fixnum)
-    (0...10).hash.should be_an_instance_of(Fixnum)
-    (0..10).hash.should be_an_instance_of(Fixnum)
+  it "generates an Integer for the hash value" do
+    (0..0).hash.should.instance_of?(Integer)
+    (0..1).hash.should.instance_of?(Integer)
+    (0...10).hash.should.instance_of?(Integer)
+    (0..10).hash.should.instance_of?(Integer)
   end
 
 end
diff --git a/spec/ruby/core/range/include_spec.rb b/spec/ruby/core/range/include_spec.rb
index b2c7a54545..66a049a90d 100644
--- a/spec/ruby/core/range/include_spec.rb
+++ b/spec/ruby/core/range/include_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'shared/cover_and_include'
 require_relative 'shared/include'
@@ -7,4 +7,8 @@ require_relative 'shared/cover'
 describe "Range#include?" do
   it_behaves_like :range_cover_and_include, :include?
   it_behaves_like :range_include, :include?
+
+  it "does not include U+9995 in the range U+0999..U+9999" do
+    ("\u{999}".."\u{9999}").include?("\u{9995}").should == false
+  end
 end
diff --git a/spec/ruby/core/range/initialize_spec.rb b/spec/ruby/core/range/initialize_spec.rb
index 8caf12baa2..b1a0565ab2 100644
--- a/spec/ruby/core/range/initialize_spec.rb
+++ b/spec/ruby/core/range/initialize_spec.rb
@@ -6,36 +6,36 @@ describe "Range#initialize" do
   end
 
   it "is private" do
-    Range.should have_private_instance_method("initialize")
+    Range.private_instance_methods(false).should.include?(:initialize)
   end
 
   it "initializes correctly the Range object when given 2 arguments" do
-    -> { @range.send(:initialize, 0, 1) }.should_not raise_error
+    -> { @range.send(:initialize, 0, 1) }.should_not.raise
   end
 
   it "initializes correctly the Range object when given 3 arguments" do
-    -> { @range.send(:initialize, 0, 1, true) }.should_not raise_error
+    -> { @range.send(:initialize, 0, 1, true) }.should_not.raise
   end
 
   it "raises an ArgumentError if passed without or with only one argument" do
-    -> { @range.send(:initialize) }.should raise_error(ArgumentError)
-    -> { @range.send(:initialize, 1) }.should raise_error(ArgumentError)
+    -> { @range.send(:initialize) }.should.raise(ArgumentError)
+    -> { @range.send(:initialize, 1) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if passed with four or more arguments" do
-    -> { @range.send(:initialize, 1, 3, 5, 7) }.should raise_error(ArgumentError)
-    -> { @range.send(:initialize, 1, 3, 5, 7, 9) }.should raise_error(ArgumentError)
+    -> { @range.send(:initialize, 1, 3, 5, 7) }.should.raise(ArgumentError)
+    -> { @range.send(:initialize, 1, 3, 5, 7, 9) }.should.raise(ArgumentError)
   end
 
-  it "raises a NameError if called on an already initialized Range" do
-    -> { (0..1).send(:initialize, 1, 3) }.should raise_error(NameError)
-    -> { (0..1).send(:initialize, 1, 3, true) }.should raise_error(NameError)
+  it "raises a FrozenError if called on an already initialized Range" do
+    -> { (0..1).send(:initialize, 1, 3) }.should.raise(FrozenError)
+    -> { (0..1).send(:initialize, 1, 3, true) }.should.raise(FrozenError)
   end
 
   it "raises an ArgumentError if arguments don't respond to <=>" do
     o1 = Object.new
     o2 = Object.new
 
-    -> { @range.send(:initialize, o1, o2) }.should raise_error(ArgumentError)
+    -> { @range.send(:initialize, o1, o2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/range/inspect_spec.rb b/spec/ruby/core/range/inspect_spec.rb
index 3c130812d0..072de123b7 100644
--- a/spec/ruby/core/range/inspect_spec.rb
+++ b/spec/ruby/core/range/inspect_spec.rb
@@ -12,15 +12,18 @@ describe "Range#inspect" do
     (0.5..2.4).inspect.should == "0.5..2.4"
   end
 
-  it "returns a tainted string if either end is tainted" do
-    (("a".taint)..."c").inspect.tainted?.should be_true
-    ("a"...("c".taint)).inspect.tainted?.should be_true
-    ("a"..."c").taint.inspect.tainted?.should be_true
+  it "works for endless ranges" do
+    eval("(1..)").inspect.should ==  "1.."
+    eval("(0.1...)").inspect.should ==  "0.1..."
   end
 
-  it "returns a untrusted string if either end is untrusted" do
-    (("a".untrust)..."c").inspect.untrusted?.should be_true
-    ("a"...("c".untrust)).inspect.untrusted?.should be_true
-    ("a"..."c").untrust.inspect.untrusted?.should be_true
+  it "works for beginless ranges" do
+    (..1).inspect.should ==  "..1"
+    (...0.1).inspect.should ==  "...0.1"
+  end
+
+  it "works for nil ... nil ranges" do
+    (..nil).inspect.should ==  "nil..nil"
+    eval("(nil...)").inspect.should ==  "nil...nil"
   end
 end
diff --git a/spec/ruby/core/range/last_spec.rb b/spec/ruby/core/range/last_spec.rb
index c7e629e62c..a7db7f85a7 100644
--- a/spec/ruby/core/range/last_spec.rb
+++ b/spec/ruby/core/range/last_spec.rb
@@ -8,6 +8,10 @@ describe "Range#last" do
     (1..5).last(3).should == [3, 4, 5]
   end
 
+  it "returns the specified number if elements for single element inclusive range" do
+    (1..1).last(1).should == [1]
+  end
+
   it "returns an empty array for an empty Range" do
     (0...0).last(2).should == []
   end
@@ -21,7 +25,7 @@ describe "Range#last" do
   end
 
   it "raises an ArgumentError when count is negative" do
-    -> { (0..2).last(-1) }.should raise_error(ArgumentError)
+    -> { (0..2).last(-1) }.should.raise(ArgumentError)
   end
 
   it "calls #to_int to convert the argument" do
@@ -32,7 +36,7 @@ describe "Range#last" do
   it "raises a TypeError if #to_int does not return an Integer" do
     obj = mock("to_int")
     obj.should_receive(:to_int).and_return("1")
-    -> { (2..3).last(obj) }.should raise_error(TypeError)
+    -> { (2..3).last(obj) }.should.raise(TypeError)
   end
 
   it "truncates the value when passed a Float" do
@@ -40,10 +44,14 @@ describe "Range#last" do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { (2..3).last(nil) }.should raise_error(TypeError)
+    -> { (2..3).last(nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { (2..3).last("1") }.should raise_error(TypeError)
+    -> { (2..3).last("1") }.should.raise(TypeError)
+  end
+
+  it "raises a RangeError when called on an endless range" do
+    -> { eval("(1..)").last }.should.raise(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/max_spec.rb b/spec/ruby/core/range/max_spec.rb
index faac0a2032..57714967ce 100644
--- a/spec/ruby/core/range/max_spec.rb
+++ b/spec/ruby/core/range/max_spec.rb
@@ -14,36 +14,65 @@ describe "Range#max" do
   end
 
   it "raises TypeError when called on an exclusive range and a non Integer value" do
-    -> { (303.20...908.1111).max }.should raise_error(TypeError)
+    -> { (303.20...908.1111).max }.should.raise(TypeError)
   end
 
   it "returns nil when the endpoint is less than the start point" do
-    (100..10).max.should be_nil
-    ('z'..'l').max.should be_nil
+    (100..10).max.should == nil
+    ('z'..'l').max.should == nil
   end
 
   it "returns nil when the endpoint equals the start point and the range is exclusive" do
-    (5...5).max.should be_nil
+    (5...5).max.should == nil
   end
 
   it "returns the endpoint when the endpoint equals the start point and the range is inclusive" do
-    (5..5).max.should equal(5)
+    (5..5).max.should.equal?(5)
   end
 
   it "returns nil when the endpoint is less than the start point in a Float range" do
-    (3003.20..908.1111).max.should be_nil
+    (3003.20..908.1111).max.should == nil
   end
 
   it "returns end point when the range is Time..Time(included end point)" do
     time_start = Time.now
     time_end = Time.now + 1.0
-    (time_start..time_end).max.should equal(time_end)
+    (time_start..time_end).max.should.equal?(time_end)
   end
 
   it "raises TypeError when called on a Time...Time(excluded end point)" do
     time_start = Time.now
     time_end = Time.now + 1.0
-    -> { (time_start...time_end).max  }.should raise_error(TypeError)
+    -> { (time_start...time_end).max  }.should.raise(TypeError)
+  end
+
+  it "raises RangeError when called on an endless range" do
+    -> { eval("(1..)").max }.should.raise(RangeError)
+  end
+
+  it "returns the end point for beginless ranges" do
+    (..1).max.should == 1
+    (..1.0).max.should == 1.0
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "raises for an exclusive beginless Integer range" do
+      -> {
+        (...1).max
+      }.should.raise(TypeError, 'cannot exclude end value with non Integer begin value')
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "returns the end point for exclusive beginless Integer ranges" do
+      (...1).max.should == 0
+    end
+  end
+
+  it "raises for an exclusive beginless non Integer range" do
+    -> {
+      (...1.0).max
+    }.should.raise(TypeError, 'cannot exclude non Integer end value')
   end
 end
 
@@ -53,7 +82,7 @@ describe "Range#max given a block" do
     (1..10).max {|a,b| acc << [a,b]; a }
     acc.flatten!
     (1..10).each do |value|
-      acc.include?(value).should be_true
+      acc.include?(value).should == true
     end
   end
 
@@ -75,8 +104,12 @@ describe "Range#max given a block" do
   end
 
   it "returns nil when the endpoint is less than the start point" do
-    (100..10).max {|x,y| x <=> y}.should be_nil
-    ('z'..'l').max {|x,y| x <=> y}.should be_nil
-    (5...5).max {|x,y| x <=> y}.should be_nil
+    (100..10).max {|x,y| x <=> y}.should == nil
+    ('z'..'l').max {|x,y| x <=> y}.should == nil
+    (5...5).max {|x,y| x <=> y}.should == nil
+  end
+
+  it "raises RangeError when called with custom comparison method on an beginless range" do
+    -> { (..1).max {|a, b| a} }.should.raise(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/member_spec.rb b/spec/ruby/core/range/member_spec.rb
index ab61f92951..78299ae9e5 100644
--- a/spec/ruby/core/range/member_spec.rb
+++ b/spec/ruby/core/range/member_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'shared/cover_and_include'
 require_relative 'shared/include'
diff --git a/spec/ruby/core/range/min_spec.rb b/spec/ruby/core/range/min_spec.rb
index 424bd1dc87..9c83d3deca 100644
--- a/spec/ruby/core/range/min_spec.rb
+++ b/spec/ruby/core/range/min_spec.rb
@@ -11,32 +11,41 @@ describe "Range#min" do
   end
 
   it "returns nil when the start point is greater than the endpoint" do
-    (100..10).min.should be_nil
-    ('z'..'l').min.should be_nil
+    (100..10).min.should == nil
+    ('z'..'l').min.should == nil
   end
 
   it "returns nil when the endpoint equals the start point and the range is exclusive" do
-    (7...7).min.should be_nil
+    (7...7).min.should == nil
   end
 
   it "returns the start point when the endpoint equals the start point and the range is inclusive" do
-    (7..7).min.should equal(7)
+    (7..7).min.should.equal?(7)
   end
 
   it "returns nil when the start point is greater than the endpoint in a Float range" do
-    (3003.20..908.1111).min.should be_nil
+    (3003.20..908.1111).min.should == nil
   end
 
   it "returns start point when the range is Time..Time(included end point)" do
     time_start = Time.now
     time_end = Time.now + 1.0
-    (time_start..time_end).min.should equal(time_start)
+    (time_start..time_end).min.should.equal?(time_start)
   end
 
   it "returns start point when the range is Time...Time(excluded end point)" do
     time_start = Time.now
     time_end = Time.now + 1.0
-    (time_start...time_end).min.should equal(time_start)
+    (time_start...time_end).min.should.equal?(time_start)
+  end
+
+  it "returns the start point for endless ranges" do
+    eval("(1..)").min.should == 1
+    eval("(1.0...)").min.should == 1.0
+  end
+
+  it "raises RangeError when called on an beginless range" do
+    -> { (..1).min }.should.raise(RangeError)
   end
 end
 
@@ -46,7 +55,7 @@ describe "Range#min given a block" do
     (1..10).min {|a,b| acc << [a,b]; a }
     acc.flatten!
     (1..10).each do |value|
-      acc.include?(value).should be_true
+      acc.include?(value).should == true
     end
   end
 
@@ -68,8 +77,12 @@ describe "Range#min given a block" do
   end
 
   it "returns nil when the start point is greater than the endpoint" do
-    (100..10).min {|x,y| x <=> y}.should be_nil
-    ('z'..'l').min {|x,y| x <=> y}.should be_nil
-    (7...7).min {|x,y| x <=> y}.should be_nil
+    (100..10).min {|x,y| x <=> y}.should == nil
+    ('z'..'l').min {|x,y| x <=> y}.should == nil
+    (7...7).min {|x,y| x <=> y}.should == nil
+  end
+
+  it "raises RangeError when called with custom comparison method on an endless range" do
+    -> { eval("(1..)").min {|a, b| a} }.should.raise(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/minmax_spec.rb b/spec/ruby/core/range/minmax_spec.rb
new file mode 100644
index 0000000000..16c7626ea3
--- /dev/null
+++ b/spec/ruby/core/range/minmax_spec.rb
@@ -0,0 +1,130 @@
+require_relative '../../spec_helper'
+
+describe 'Range#minmax' do
+  before(:each) do
+    @x = mock('x')
+    @y = mock('y')
+
+    @x.should_receive(:<=>).with(@y).any_number_of_times.and_return(-1) # x < y
+    @x.should_receive(:<=>).with(@x).any_number_of_times.and_return(0) # x == x
+    @y.should_receive(:<=>).with(@x).any_number_of_times.and_return(1) # y > x
+    @y.should_receive(:<=>).with(@y).any_number_of_times.and_return(0) # y == y
+  end
+
+  describe 'on an inclusive range' do
+    it 'should raise RangeError on an endless range without iterating the range' do
+      @x.should_not_receive(:succ)
+
+      range = (@x..)
+
+      -> { range.minmax }.should.raise(RangeError, 'cannot get the maximum of endless range')
+    end
+
+    it 'raises RangeError or ArgumentError on a beginless range' do
+      range = (..@x)
+
+      -> { range.minmax }.should.raise(StandardError) { |e|
+        if RangeError === e
+          # error from #min
+          -> { raise e }.should.raise(RangeError, 'cannot get the minimum of beginless range')
+        else
+          # error from #max
+          -> { raise e }.should.raise(ArgumentError, 'comparison of NilClass with MockObject failed')
+        end
+      }
+    end
+
+    it 'should return beginning of range if beginning and end are equal without iterating the range' do
+      @x.should_not_receive(:succ)
+
+      (@x..@x).minmax.should == [@x, @x]
+    end
+
+    it 'should return nil pair if beginning is greater than end without iterating the range' do
+      @y.should_not_receive(:succ)
+
+      (@y..@x).minmax.should == [nil, nil]
+    end
+
+    it 'should return the minimum and maximum values for a non-numeric range without iterating the range' do
+      @x.should_not_receive(:succ)
+
+      (@x..@y).minmax.should == [@x, @y]
+    end
+
+    it 'should return the minimum and maximum values for a numeric range' do
+      (1..3).minmax.should == [1, 3]
+    end
+
+    it 'should return the minimum and maximum values for a numeric range without iterating the range' do
+      # We cannot set expectations on integers,
+      # so we "prevent" iteration by picking a value that would iterate until the spec times out.
+      range_end = Float::INFINITY
+
+      (1..range_end).minmax.should == [1, range_end]
+    end
+
+    it 'should return the minimum and maximum values according to the provided block by iterating the range' do
+      @x.should_receive(:succ).once.and_return(@y)
+
+      (@x..@y).minmax { |x, y| - (x <=> y) }.should == [@y, @x]
+    end
+  end
+
+  describe 'on an exclusive range' do
+    it 'should raise RangeError on an endless range' do
+      @x.should_not_receive(:succ)
+      range = (@x...)
+
+      -> { range.minmax }.should.raise(RangeError, 'cannot get the maximum of endless range')
+    end
+
+    it 'should raise RangeError on a beginless range' do
+      range = (...@x)
+
+      -> { range.minmax }.should.raise(RangeError,
+        /cannot get the maximum of beginless range with custom comparison method|cannot get the minimum of beginless range/)
+    end
+
+    it 'should return nil pair if beginning and end are equal without iterating the range' do
+      @x.should_not_receive(:succ)
+
+      (@x...@x).minmax.should == [nil, nil]
+    end
+
+    it 'should return nil pair if beginning is greater than end without iterating the range' do
+      @y.should_not_receive(:succ)
+
+      (@y...@x).minmax.should == [nil, nil]
+    end
+
+    it 'should return the minimum and maximum values for a non-numeric range by iterating the range' do
+      @x.should_receive(:succ).once.and_return(@y)
+
+      (@x...@y).minmax.should == [@x, @x]
+    end
+
+    it 'should return the minimum and maximum values for a numeric range' do
+      (1...3).minmax.should == [1, 2]
+    end
+
+    it 'should return the minimum and maximum values for a numeric range without iterating the range' do
+      # We cannot set expectations on integers,
+      # so we "prevent" iteration by picking a value that would iterate until the spec times out.
+      range_end = bignum_value
+
+      (1...range_end).minmax.should == [1, range_end - 1]
+    end
+
+    it 'raises TypeError if the end value is not an integer' do
+      range = (0...Float::INFINITY)
+      -> { range.minmax }.should.raise(TypeError, 'cannot exclude non Integer end value')
+    end
+
+    it 'should return the minimum and maximum values according to the provided block by iterating the range' do
+      @x.should_receive(:succ).once.and_return(@y)
+
+      (@x...@y).minmax { |x, y| - (x <=> y) }.should == [@x, @x]
+    end
+  end
+end
diff --git a/spec/ruby/core/range/new_spec.rb b/spec/ruby/core/range/new_spec.rb
index 9ed2b65d5a..9a35f28c7e 100644
--- a/spec/ruby/core/range/new_spec.rb
+++ b/spec/ruby/core/range/new_spec.rb
@@ -25,63 +25,53 @@ describe "Range.new" do
   end
 
   it "raises an ArgumentError when the given start and end can't be compared by using #<=>" do
-    -> { Range.new(1, mock('x'))         }.should raise_error(ArgumentError)
-    -> { Range.new(mock('x'), mock('y')) }.should raise_error(ArgumentError)
+    -> { Range.new(1, mock('x'))         }.should.raise(ArgumentError)
+    -> { Range.new(mock('x'), mock('y')) }.should.raise(ArgumentError)
 
     b = mock('x')
     (a = mock('nil')).should_receive(:<=>).with(b).and_return(nil)
-    -> { Range.new(a, b) }.should raise_error(ArgumentError)
+    -> { Range.new(a, b) }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.5" do
-    it "does not rescue exception raised in #<=> when compares the given start and end" do
-      b = mock('a')
-      a = mock('b')
-      a.should_receive(:<=>).with(b).and_raise(RangeSpecs::ComparisonError)
+  it "does not rescue exception raised in #<=> when compares the given start and end" do
+    b = mock('a')
+    a = mock('b')
+    a.should_receive(:<=>).with(b).and_raise(RangeSpecs::ComparisonError)
 
-      -> { Range.new(a, b) }.should raise_error(RangeSpecs::ComparisonError)
-    end
+    -> { Range.new(a, b) }.should.raise(RangeSpecs::ComparisonError)
   end
 
   describe "beginless/endless range" do
-    ruby_version_is ""..."2.7" do
-      it "does not allow range without left boundary" do
-        -> { Range.new(nil, 1) }.should raise_error(ArgumentError, /bad value for range/)
-      end
+    it "allows beginless left boundary" do
+      range = Range.new(nil, 1)
+      range.begin.should == nil
     end
 
-    ruby_version_is "2.7" do
-      it "allows beginless left boundary" do
-        range = Range.new(nil, 1)
-        range.begin.should == nil
-      end
-
-      it "distinguishes ranges with included and excluded right boundary" do
-        range_exclude = Range.new(nil, 1, true)
-        range_include = Range.new(nil, 1, false)
+    it "distinguishes ranges with included and excluded right boundary" do
+      range_exclude = Range.new(nil, 1, true)
+      range_include = Range.new(nil, 1, false)
 
-        range_exclude.should_not == range_include
-      end
+      range_exclude.should_not == range_include
     end
 
-    ruby_version_is ""..."2.6" do
-      it "does not allow range without right boundary" do
-        -> { Range.new(1, nil) }.should raise_error(ArgumentError, /bad value for range/)
-      end
+    it "allows endless right boundary" do
+      range = Range.new(1, nil)
+      range.end.should == nil
     end
 
-    ruby_version_is "2.6" do
-      it "allows endless right boundary" do
-        range = Range.new(1, nil)
-        range.end.should == nil
-      end
+    it "distinguishes ranges with included and excluded right boundary" do
+      range_exclude = Range.new(1, nil, true)
+      range_include = Range.new(1, nil, false)
 
-      it "distinguishes ranges with included and excluded right boundary" do
-        range_exclude = Range.new(1, nil, true)
-        range_include = Range.new(1, nil, false)
+      range_exclude.should_not == range_include
+    end
+
+    it "creates a frozen range if the class is Range.class" do
+      Range.new(1, 2).should.frozen?
+    end
 
-        range_exclude.should_not == range_include
-      end
+    it "does not create a frozen range if the class is not Range.class" do
+      Class.new(Range).new(1, 2).should_not.frozen?
     end
   end
 end
diff --git a/spec/ruby/core/range/overlap_spec.rb b/spec/ruby/core/range/overlap_spec.rb
new file mode 100644
index 0000000000..201cd2b1ff
--- /dev/null
+++ b/spec/ruby/core/range/overlap_spec.rb
@@ -0,0 +1,87 @@
+require_relative '../../spec_helper'
+
+describe "Range#overlap?" do
+  it "returns true if other Range overlaps self" do
+    (0..2).overlap?(1..3).should == true
+    (1..3).overlap?(0..2).should == true
+    (0..2).overlap?(0..2).should == true
+    (0..3).overlap?(1..2).should == true
+    (1..2).overlap?(0..3).should == true
+
+    ('a'..'c').overlap?('b'..'d').should == true
+  end
+
+  it "returns false if other Range does not overlap self" do
+    (0..2).overlap?(3..4).should == false
+    (0..2).overlap?(-4..-1).should == false
+
+    ('a'..'c').overlap?('d'..'f').should == false
+  end
+
+  it "raises TypeError when called with non-Range argument" do
+    -> {
+      (0..2).overlap?(1)
+    }.should.raise(TypeError, "wrong argument type Integer (expected Range)")
+  end
+
+  it "returns true when beginningless and endless Ranges overlap" do
+    (0..2).overlap?(..3).should == true
+    (0..2).overlap?(..1).should == true
+    (0..2).overlap?(..0).should == true
+
+    (..3).overlap?(0..2).should == true
+    (..1).overlap?(0..2).should == true
+    (..0).overlap?(0..2).should == true
+
+    (0..2).overlap?(-1..).should == true
+    (0..2).overlap?(1..).should == true
+    (0..2).overlap?(2..).should == true
+
+    (-1..).overlap?(0..2).should == true
+    (1..).overlap?(0..2).should == true
+    (2..).overlap?(0..2).should == true
+
+    (0..).overlap?(2..).should == true
+    (..0).overlap?(..2).should == true
+  end
+
+  it "returns false when beginningless and endless Ranges do not overlap" do
+    (0..2).overlap?(..-1).should == false
+    (0..2).overlap?(3..).should == false
+
+    (..-1).overlap?(0..2).should == false
+    (3..).overlap?(0..2).should == false
+  end
+
+  it "returns false when Ranges are not compatible" do
+    (0..2).overlap?('a'..'d').should == false
+  end
+
+  it "return false when self is empty" do
+    (2..0).overlap?(1..3).should == false
+    (2...2).overlap?(1..3).should == false
+    (1...1).overlap?(1...1).should == false
+    (2..0).overlap?(2..0).should == false
+
+    ('c'..'a').overlap?('b'..'d').should == false
+    ('a'...'a').overlap?('b'..'d').should == false
+    ('b'...'b').overlap?('b'...'b').should == false
+    ('c'...'a').overlap?('c'...'a').should == false
+  end
+
+  it "return false when other Range is empty" do
+    (1..3).overlap?(2..0).should == false
+    (1..3).overlap?(2...2).should == false
+
+    ('b'..'d').overlap?('c'..'a').should == false
+    ('b'..'d').overlap?('c'...'c').should == false
+  end
+
+  it "takes into account exclusive end" do
+    (0...2).overlap?(2..4).should == false
+    (2..4).overlap?(0...2).should == false
+
+    ('a'...'c').overlap?('c'..'e').should == false
+    ('c'..'e').overlap?('a'...'c').should == false
+  end
+end
diff --git a/spec/ruby/core/range/percent_spec.rb b/spec/ruby/core/range/percent_spec.rb
index 41badd4f72..5ec6770ddb 100644
--- a/spec/ruby/core/range/percent_spec.rb
+++ b/spec/ruby/core/range/percent_spec.rb
@@ -1,18 +1,16 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Range#%" do
-    it "works as a Range#step" do
-      aseq = (1..10) % 2
-      aseq.class.should == Enumerator::ArithmeticSequence
-      aseq.begin.should == 1
-      aseq.end.should == 10
-      aseq.step.should == 2
-      aseq.to_a.should == [1, 3, 5, 7, 9]
-    end
+describe "Range#%" do
+  it "works as a Range#step" do
+    aseq = (1..10) % 2
+    aseq.class.should == Enumerator::ArithmeticSequence
+    aseq.begin.should == 1
+    aseq.end.should == 10
+    aseq.step.should == 2
+    aseq.to_a.should == [1, 3, 5, 7, 9]
+  end
 
-    it "produces an arithmetic sequence with a percent sign in #inspect" do
-      ((1..10) % 2).inspect.should == "((1..10).%(2))"
-    end
+  it "produces an arithmetic sequence with a percent sign in #inspect" do
+    ((1..10) % 2).inspect.should == "((1..10).%(2))"
   end
 end
diff --git a/spec/ruby/core/range/reverse_each_spec.rb b/spec/ruby/core/range/reverse_each_spec.rb
new file mode 100644
index 0000000000..49790e8b0a
--- /dev/null
+++ b/spec/ruby/core/range/reverse_each_spec.rb
@@ -0,0 +1,125 @@
+require_relative '../../spec_helper'
+
+describe "Range#reverse_each" do
+  it "traverses the Range in reverse order and passes each element to block" do
+    a = []
+    (1..3).reverse_each { |i| a << i }
+    a.should == [3, 2, 1]
+
+    a = []
+    (1...3).reverse_each { |i| a << i }
+    a.should == [2, 1]
+  end
+
+  it "returns self" do
+    r = (1..3)
+    r.reverse_each { |x| }.should.equal?(r)
+  end
+
+  it "returns an Enumerator if no block given" do
+    enum = (1..3).reverse_each
+    enum.should.instance_of?(Enumerator)
+    enum.to_a.should == [3, 2, 1]
+  end
+
+  it "raises a TypeError for endless Ranges of Integers" do
+    -> {
+      (1..).reverse_each.take(3)
+    }.should.raise(TypeError, "can't iterate from NilClass")
+  end
+
+  it "raises a TypeError for endless Ranges of non-Integers" do
+    -> {
+      ("a"..).reverse_each.take(3)
+    }.should.raise(TypeError, "can't iterate from NilClass")
+  end
+
+  context "Integer boundaries" do
+    it "supports beginningless Ranges" do
+      (..5).reverse_each.take(3).should == [5, 4, 3]
+    end
+  end
+
+  context "non-Integer boundaries" do
+    it "uses #succ to iterate a Range of non-Integer elements" do
+      y = mock('y')
+      x = mock('x')
+
+      x.should_receive(:succ).any_number_of_times.and_return(y)
+      x.should_receive(:<=>).with(y).any_number_of_times.and_return(-1)
+      x.should_receive(:<=>).with(x).any_number_of_times.and_return(0)
+      y.should_receive(:<=>).with(x).any_number_of_times.and_return(1)
+      y.should_receive(:<=>).with(y).any_number_of_times.and_return(0)
+
+      a = []
+      (x..y).each { |i| a << i }
+      a.should == [x, y]
+    end
+
+    it "uses #succ to iterate a Range of Strings" do
+      a = []
+      ('A'..'D').reverse_each { |i| a << i }
+      a.should == ['D','C','B','A']
+    end
+
+    it "uses #succ to iterate a Range of Symbols" do
+      a = []
+      (:A..:D).reverse_each { |i| a << i }
+      a.should == [:D, :C, :B, :A]
+    end
+
+    it "raises a TypeError when `begin` value does not respond to #succ" do
+      -> { (Time.now..Time.now).reverse_each { |x| x } }.should.raise(TypeError, /can't iterate from Time/)
+      -> { (//..//).reverse_each { |x| x } }.should.raise(TypeError, /can't iterate from Regexp/)
+      -> { ([]..[]).reverse_each { |x| x } }.should.raise(TypeError, /can't iterate from Array/)
+    end
+
+    it "does not support beginningless Ranges" do
+      -> {
+        (..'a').reverse_each { |x| x }
+      }.should.raise(TypeError, /can't iterate from NilClass/)
+    end
+  end
+
+  context "when no block is given" do
+    describe "returned Enumerator size" do
+      it "returns the Range size when Range size is finite" do
+        (1..3).reverse_each.size.should == 3
+        (1...3).reverse_each.size.should == 2
+
+        (1..3.3).reverse_each.size.should == 3
+        (1...3.3).reverse_each.size.should == 3
+      end
+
+      ruby_version_is ""..."3.4" do
+        it "returns a size when it is not iterable" do
+          (1.1..3).reverse_each.size.should == 2
+          (1.1..3.3).reverse_each.size.should == 3
+          (1.1..nil).reverse_each.size.should == Float::INFINITY
+          (nil..3.3).reverse_each.size.should == Float::INFINITY
+          (nil..nil).reverse_each.size.should == nil
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "raises TypeError when the range is not iterable" do
+          -> { (1.1..3).reverse_each.size }.should.raise(TypeError, /can't iterate from Integer/)
+          -> { (1.1..3.3).reverse_each.size }.should.raise(TypeError, /can't iterate from Float/)
+          -> { (1.1..nil).reverse_each.size }.should.raise(TypeError, /can't iterate from NilClass/)
+          -> { (nil..3.3).reverse_each.size }.should.raise(TypeError, /can't iterate from Float/)
+          -> { (nil..nil).reverse_each.size }.should.raise(TypeError, /can't iterate from NilClass/)
+        end
+      end
+
+      ruby_bug "#20936", "3.4"..."4.0" do
+        it "returns Infinity when Range size is infinite" do
+          (..3).reverse_each.size.should == Float::INFINITY
+        end
+      end
+
+      it "returns nil when Range size is unknown" do
+        ('a'..'z').reverse_each.size.should == nil
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/range/shared/cover.rb b/spec/ruby/core/range/shared/cover.rb
index 33d416fef5..189f3da4bf 100644
--- a/spec/ruby/core/range/shared/cover.rb
+++ b/spec/ruby/core/range/shared/cover.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
@@ -6,26 +6,26 @@ describe :range_cover, shared: true do
   it "uses the range element's <=> to make the comparison" do
     a = mock('a')
     a.should_receive(:<=>).twice.and_return(-1,-1)
-    (a..'z').send(@method, 'b').should be_true
+    (a..'z').send(@method, 'b').should == true
   end
 
   it "uses a continuous inclusion test" do
-    ('a'..'f').send(@method, 'aa').should be_true
-    ('a'..'f').send(@method, 'babe').should be_true
-    ('a'..'f').send(@method, 'baby').should be_true
-    ('a'..'f').send(@method, 'ga').should be_false
-    (-10..-2).send(@method, -2.5).should be_true
+    ('a'..'f').send(@method, 'aa').should == true
+    ('a'..'f').send(@method, 'babe').should == true
+    ('a'..'f').send(@method, 'baby').should == true
+    ('a'..'f').send(@method, 'ga').should == false
+    (-10..-2).send(@method, -2.5).should == true
   end
 
   describe "on string elements" do
     it "returns true if other is matched by element.succ" do
-      ('a'..'c').send(@method, 'b').should be_true
-      ('a'...'c').send(@method, 'b').should be_true
+      ('a'..'c').send(@method, 'b').should == true
+      ('a'...'c').send(@method, 'b').should == true
     end
 
     it "returns true if other is not matched by element.succ" do
-      ('a'..'c').send(@method, 'bc').should be_true
-      ('a'...'c').send(@method, 'bc').should be_true
+      ('a'..'c').send(@method, 'bc').should == true
+      ('a'...'c').send(@method, 'bc').should == true
     end
   end
 
@@ -36,27 +36,27 @@ describe :range_cover, shared: true do
       end
 
       it "returns false if other is less than first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should == false
       end
 
       it "returns true if other is equal as first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should == true
       end
 
       it "returns true if other is matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should == true
       end
 
       it "returns true if other is not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should == true
       end
 
       it "returns true if other is equal as last element but not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should == true
       end
 
       it "returns false if other is greater than last element but matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should == false
       end
     end
 
@@ -66,88 +66,128 @@ describe :range_cover, shared: true do
       end
 
       it "returns false if other is less than first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should == false
       end
 
       it "returns true if other is equal as first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should == true
       end
 
       it "returns true if other is matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should == true
       end
 
       it "returns true if other is not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should == true
       end
 
       it "returns false if other is equal as last element but not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should == false
       end
 
       it "returns false if other is greater than last element but matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should == false
       end
     end
   end
+end
 
-  ruby_version_is "2.6" do
-    context "range argument" do
-      it "accepts range argument" do
-        (0..10).send(@method, (3..7)).should be_true
-        (0..10).send(@method, (3..15)).should be_false
-        (0..10).send(@method, (-2..7)).should be_false
-
-        (1.1..7.9).send(@method, (2.5..6.5)).should be_true
-        (1.1..7.9).send(@method, (2.5..8.5)).should be_false
-        (1.1..7.9).send(@method, (0.5..6.5)).should be_false
-
-        ('c'..'i').send(@method, ('d'..'f')).should be_true
-        ('c'..'i').send(@method, ('d'..'z')).should be_false
-        ('c'..'i').send(@method, ('a'..'f')).should be_false
-
-        range_10_100 = RangeSpecs::TenfoldSucc.new(10)..RangeSpecs::TenfoldSucc.new(100)
-        range_20_90 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(90)
-        range_20_110 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(110)
-        range_0_90 = RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(90)
-
-        range_10_100.send(@method, range_20_90).should be_true
-        range_10_100.send(@method, range_20_110).should be_false
-        range_10_100.send(@method, range_0_90).should be_false
-      end
+describe :range_cover_subrange, shared: true do
+  context "range argument" do
+    it "accepts range argument" do
+      (0..10).send(@method, (3..7)).should == true
+      (0..10).send(@method, (3..15)).should == false
+      (0..10).send(@method, (-2..7)).should == false
+
+      (1.1..7.9).send(@method, (2.5..6.5)).should == true
+      (1.1..7.9).send(@method, (2.5..8.5)).should == false
+      (1.1..7.9).send(@method, (0.5..6.5)).should == false
+
+      ('c'..'i').send(@method, ('d'..'f')).should == true
+      ('c'..'i').send(@method, ('d'..'z')).should == false
+      ('c'..'i').send(@method, ('a'..'f')).should == false
+
+      range_10_100 = RangeSpecs::TenfoldSucc.new(10)..RangeSpecs::TenfoldSucc.new(100)
+      range_20_90 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(90)
+      range_20_110 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(110)
+      range_0_90 = RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(90)
+
+      range_10_100.send(@method, range_20_90).should == true
+      range_10_100.send(@method, range_20_110).should == false
+      range_10_100.send(@method, range_0_90).should == false
+    end
 
-      it "supports boundaries of different comparable types" do
-        (0..10).send(@method, (3.1..7.9)).should be_true
-        (0..10).send(@method, (3.1..15.9)).should be_false
-        (0..10).send(@method, (-2.1..7.9)).should be_false
-      end
+    it "supports boundaries of different comparable types" do
+      (0..10).send(@method, (3.1..7.9)).should == true
+      (0..10).send(@method, (3.1..15.9)).should == false
+      (0..10).send(@method, (-2.1..7.9)).should == false
+    end
 
-      it "returns false if types are not comparable" do
-        (0..10).send(@method, ('a'..'z')).should be_false
-        (0..10).send(@method, (RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(100))).should be_false
-      end
+    it "returns false if types are not comparable" do
+      (0..10).send(@method, ('a'..'z')).should == false
+      (0..10).send(@method, (RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(100))).should == false
+    end
 
-      it "honors exclusion of right boundary (:exclude_end option)" do
-        # Integer
-        (0..10).send(@method, (0..10)).should be_true
-        (0...10).send(@method, (0...10)).should be_true
+    it "honors exclusion of right boundary (:exclude_end option)" do
+      # Integer
+      (0..10).send(@method, (0..10)).should == true
+      (0...10).send(@method, (0...10)).should == true
 
-        (0..10).send(@method, (0...10)).should be_true
-        (0...10).send(@method, (0..10)).should be_false
+      (0..10).send(@method, (0...10)).should == true
+      (0...10).send(@method, (0..10)).should == false
 
-        (0...11).send(@method, (0..10)).should be_true
-        (0..10).send(@method, (0...11)).should be_true
+      (0...11).send(@method, (0..10)).should == true
+      (0..10).send(@method, (0...11)).should == true
 
-        # Float
-        (0..10.1).send(@method, (0..10.1)).should be_true
-        (0...10.1).send(@method, (0...10.1)).should be_true
+      # Float
+      (0..10.1).send(@method, (0..10.1)).should == true
+      (0...10.1).send(@method, (0...10.1)).should == true
 
-        (0..10.1).send(@method, (0...10.1)).should be_true
-        (0...10.1).send(@method, (0..10.1)).should be_false
+      (0..10.1).send(@method, (0...10.1)).should == true
+      (0...10.1).send(@method, (0..10.1)).should == false
 
-        (0...11.1).send(@method, (0..10.1)).should be_true
-        (0..10.1).send(@method, (0...11.1)).should be_false
-      end
+      (0...11.1).send(@method, (0..10.1)).should == true
+      (0..10.1).send(@method, (0...11.1)).should == false
     end
   end
+
+  it "allows self to be a beginless range" do
+    (...10).send(@method, (3..7)).should == true
+    (...10).send(@method, (3..15)).should == false
+
+    (..7.9).send(@method, (2.5..6.5)).should == true
+    (..7.9).send(@method, (2.5..8.5)).should == false
+
+    (..'i').send(@method, ('d'..'f')).should == true
+    (..'i').send(@method, ('d'..'z')).should == false
+  end
+
+  it "allows self to be a endless range" do
+    eval("(0...)").send(@method, (3..7)).should == true
+    eval("(5...)").send(@method, (3..15)).should == false
+
+    eval("(1.1..)").send(@method, (2.5..6.5)).should == true
+    eval("(3.3..)").send(@method, (2.5..8.5)).should == false
+
+    eval("('a'..)").send(@method, ('d'..'f')).should == true
+    eval("('p'..)").send(@method, ('d'..'z')).should == false
+  end
+
+  it "accepts beginless range argument" do
+    (..10).send(@method, (...10)).should == true
+    (0..10).send(@method, (...10)).should == false
+
+    (1.1..7.9).send(@method, (...10.5)).should == false
+
+    ('c'..'i').send(@method, (..'i')).should == false
+  end
+
+  it "accepts endless range argument" do
+    eval("(0..)").send(@method, eval("(0...)")).should == true
+    (0..10).send(@method, eval("(0...)")).should == false
+
+    (1.1..7.9).send(@method, eval("(0.8...)")).should == false
+
+    ('c'..'i').send(@method, eval("('a'..)")).should == false
+  end
 end
diff --git a/spec/ruby/core/range/shared/cover_and_include.rb b/spec/ruby/core/range/shared/cover_and_include.rb
index a19e2c6ead..97721a7307 100644
--- a/spec/ruby/core/range/shared/cover_and_include.rb
+++ b/spec/ruby/core/range/shared/cover_and_include.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 
 describe :range_cover_and_include, shared: true do
@@ -19,48 +19,68 @@ describe :range_cover_and_include, shared: true do
     (0.5...2.4).send(@method, 2.4).should == false
   end
 
+  it "returns true if other is an element of self for endless ranges" do
+    (1..).send(@method, 2.4).should == true
+    (0.5...).send(@method, 2.4).should == true
+  end
+
+  it "returns true if other is an element of self for beginless ranges" do
+    (..10).send(@method, 2.4).should == true
+    (...10.5).send(@method, 2.4).should == true
+  end
+
+  it "returns false if values are not comparable" do
+    (1..10).send(@method, nil).should == false
+    (1...10).send(@method, nil).should == false
+
+    (..10).send(@method, nil).should == false
+    (...10).send(@method, nil).should == false
+
+    (1..).send(@method, nil).should == false
+    (1...).send(@method, nil).should == false
+  end
+
   it "compares values using <=>" do
     rng = (1..5)
     m = mock("int")
     m.should_receive(:coerce).and_return([1, 2])
     m.should_receive(:<=>).and_return(1)
 
-    rng.send(@method, m).should be_false
+    rng.send(@method, m).should == false
   end
 
   it "raises an ArgumentError without exactly one argument" do
-    ->{ (1..2).send(@method) }.should raise_error(ArgumentError)
-    ->{ (1..2).send(@method, 1, 2) }.should raise_error(ArgumentError)
+    ->{ (1..2).send(@method) }.should.raise(ArgumentError)
+    ->{ (1..2).send(@method, 1, 2) }.should.raise(ArgumentError)
   end
 
   it "returns true if argument is equal to the first value of the range" do
-    (0..5).send(@method, 0).should be_true
-    ('f'..'s').send(@method, 'f').should be_true
+    (0..5).send(@method, 0).should == true
+    ('f'..'s').send(@method, 'f').should == true
   end
 
   it "returns true if argument is equal to the last value of the range" do
-    (0..5).send(@method, 5).should be_true
-    (0...5).send(@method, 4).should be_true
-    ('f'..'s').send(@method, 's').should be_true
+    (0..5).send(@method, 5).should == true
+    (0...5).send(@method, 4).should == true
+    ('f'..'s').send(@method, 's').should == true
   end
 
   it "returns true if argument is less than the last value of the range and greater than the first value" do
-    (20..30).send(@method, 28).should be_true
-    ('e'..'h').send(@method, 'g').should be_true
-    ("\u{999}".."\u{9999}").send @method, "\u{9995}"
+    (20..30).send(@method, 28).should == true
+    ('e'..'h').send(@method, 'g').should == true
   end
 
   it "returns true if argument is sole element in the range" do
-    (30..30).send(@method, 30).should be_true
+    (30..30).send(@method, 30).should == true
   end
 
   it "returns false if range is empty" do
-    (30...30).send(@method, 30).should be_false
-    (30...30).send(@method, nil).should be_false
+    (30...30).send(@method, 30).should == false
+    (30...30).send(@method, nil).should == false
   end
 
   it "returns false if the range does not contain the argument" do
-    ('A'..'C').send(@method, 20.9).should be_false
-    ('A'...'C').send(@method, 'C').should be_false
+    ('A'..'C').send(@method, 20.9).should == false
+    ('A'...'C').send(@method, 'C').should == false
   end
 end
diff --git a/spec/ruby/core/range/shared/equal_value.rb b/spec/ruby/core/range/shared/equal_value.rb
index 9d8bb13351..363c6be558 100644
--- a/spec/ruby/core/range/shared/equal_value.rb
+++ b/spec/ruby/core/range/shared/equal_value.rb
@@ -42,4 +42,10 @@ describe :range_eql, shared: true do
     b = RangeSpecs::MyRange.new(RangeSpecs::Xs.new(3), RangeSpecs::Xs.new(5))
     a.send(@method, b).should == true
   end
+
+  it "works for endless Ranges" do
+    eval("(1..)").send(@method, eval("(1..)")).should == true
+    eval("(0.5...)").send(@method, eval("(0.5...)")).should == true
+    eval("(1..)").send(@method, eval("(1...)")).should == false
+  end
 end
diff --git a/spec/ruby/core/range/shared/include.rb b/spec/ruby/core/range/shared/include.rb
index c6c5c2becf..5f0db48008 100644
--- a/spec/ruby/core/range/shared/include.rb
+++ b/spec/ruby/core/range/shared/include.rb
@@ -1,17 +1,17 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
 describe :range_include, shared: true do
   describe "on string elements" do
     it "returns true if other is matched by element.succ" do
-      ('a'..'c').send(@method, 'b').should be_true
-      ('a'...'c').send(@method, 'b').should be_true
+      ('a'..'c').send(@method, 'b').should == true
+      ('a'...'c').send(@method, 'b').should == true
     end
 
     it "returns false if other is not matched by element.succ" do
-      ('a'..'c').send(@method, 'bc').should be_false
-      ('a'...'c').send(@method, 'bc').should be_false
+      ('a'..'c').send(@method, 'bc').should == false
+      ('a'...'c').send(@method, 'bc').should == false
     end
   end
 
@@ -22,27 +22,27 @@ describe :range_include, shared: true do
       end
 
       it "returns false if other is less than first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should == false
       end
 
       it "returns true if other is equal as first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should == true
       end
 
       it "returns true if other is matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should == true
       end
 
       it "returns false if other is not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should == false
       end
 
       it "returns false if other is equal as last element but not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should == false
       end
 
       it "returns false if other is greater than last element but matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should == false
       end
     end
 
@@ -52,27 +52,27 @@ describe :range_include, shared: true do
       end
 
       it "returns false if other is less than first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(0)).should == false
       end
 
       it "returns true if other is equal as first element" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(1)).should == true
       end
 
       it "returns true if other is matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should be_true
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(10)).should == true
       end
 
       it "returns false if other is not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(2)).should == false
       end
 
       it "returns false if other is equal as last element but not matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(99)).should == false
       end
 
       it "returns false if other is greater than last element but matched by element.succ" do
-        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should be_false
+        @range.send(@method, RangeSpecs::TenfoldSucc.new(100)).should == false
       end
     end
   end
diff --git a/spec/ruby/core/range/size_spec.rb b/spec/ruby/core/range/size_spec.rb
index 09759940dd..3a8843b99d 100644
--- a/spec/ruby/core/range/size_spec.rb
+++ b/spec/ruby/core/range/size_spec.rb
@@ -4,28 +4,89 @@ describe "Range#size" do
   it "returns the number of elements in the range" do
     (1..16).size.should == 16
     (1...16).size.should == 15
-
-    (1.0..16.0).size.should == 16
-    (1.0...16.0).size.should == 15
-    (1.0..15.9).size.should == 15
-    (1.1..16.0).size.should == 15
-    (1.1..15.9).size.should == 15
   end
 
   it "returns 0 if last is less than first" do
     (16..0).size.should == 0
-    (16.0..0.0).size.should == 0
-    (Float::INFINITY..0).size.should == 0
   end
 
   it 'returns Float::INFINITY for increasing, infinite ranges' do
     (0..Float::INFINITY).size.should == Float::INFINITY
-    (-Float::INFINITY..0).size.should == Float::INFINITY
-    (-Float::INFINITY..Float::INFINITY).size.should == Float::INFINITY
+  end
+
+  it 'returns Float::INFINITY for endless ranges if the start is numeric' do
+    eval("(1..)").size.should == Float::INFINITY
+  end
+
+  it 'returns nil for endless ranges if the start is not numeric' do
+    eval("('z'..)").size.should == nil
+  end
+
+  ruby_version_is ""..."3.4" do
+    it 'returns Float::INFINITY for all beginless ranges if the end is numeric' do
+      (..1).size.should == Float::INFINITY
+      (...0.5).size.should == Float::INFINITY
+    end
+
+    it 'returns nil for all beginless ranges if the end is not numeric' do
+      (...'o').size.should == nil
+    end
+
+    it 'returns nil if the start and the end is both nil' do
+      (nil..nil).size.should == nil
+    end
+  end
+
+  ruby_version_is ""..."3.4" do
+    it "returns the number of elements in the range" do
+      (1.0..16.0).size.should == 16
+      (1.0...16.0).size.should == 15
+      (1.0..15.9).size.should == 15
+      (1.1..16.0).size.should == 15
+      (1.1..15.9).size.should == 15
+    end
+
+    it "returns 0 if last is less than first" do
+      (16.0..0.0).size.should == 0
+      (Float::INFINITY..0).size.should == 0
+    end
+
+    it 'returns Float::INFINITY for increasing, infinite ranges' do
+      (-Float::INFINITY..0).size.should == Float::INFINITY
+      (-Float::INFINITY..Float::INFINITY).size.should == Float::INFINITY
+    end
+
+    it 'returns Float::INFINITY for endless ranges if the start is numeric' do
+      eval("(0.5...)").size.should == Float::INFINITY
+    end
+
+    it 'returns nil for endless ranges if the start is not numeric' do
+      eval("([]...)").size.should == nil
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it 'raises TypeError if a range is not iterable' do
+      -> { (1.0..16.0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (1.0...16.0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (1.0..15.9).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (1.1..16.0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (1.1..15.9).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (16.0..0.0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (Float::INFINITY..0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (-Float::INFINITY..0).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (-Float::INFINITY..Float::INFINITY).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (..1).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (...0.5).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (..nil).size }.should.raise(TypeError, /can't iterate from/)
+      -> { (...'o').size }.should.raise(TypeError, /can't iterate from/)
+      -> { eval("(0.5...)").size }.should.raise(TypeError, /can't iterate from/)
+      -> { eval("([]...)").size }.should.raise(TypeError, /can't iterate from/)
+    end
   end
 
   it "returns nil if first and last are not Numeric" do
-    (:a..:z).size.should be_nil
-    ('a'..'z').size.should be_nil
+    (:a..:z).size.should == nil
+    ('a'..'z').size.should == nil
   end
 end
diff --git a/spec/ruby/core/range/step_spec.rb b/spec/ruby/core/range/step_spec.rb
index d564e4a5cd..faab95d88d 100644
--- a/spec/ruby/core/range/step_spec.rb
+++ b/spec/ruby/core/range/step_spec.rb
@@ -7,143 +7,188 @@ describe "Range#step" do
 
   it "returns self" do
     r = 1..2
-    r.step { }.should equal(r)
+    r.step { }.should.equal?(r)
   end
 
-  it "raises TypeError if step" do
-    obj = mock("mock")
-    -> { (1..10).step(obj) { } }.should raise_error(TypeError)
-  end
+  ruby_version_is ""..."3.4" do
+    it "calls #to_int to coerce step to an Integer" do
+      obj = mock("Range#step")
+      obj.should_receive(:to_int).and_return(1)
 
-  it "calls #to_int to coerce step to an Integer" do
-    obj = mock("Range#step")
-    obj.should_receive(:to_int).and_return(1)
+      (1..2).step(obj) { |x| ScratchPad << x }
+      ScratchPad.recorded.should.eql?([1, 2])
+    end
 
-    (1..2).step(obj) { |x| ScratchPad << x }
-    ScratchPad.recorded.should eql([1, 2])
-  end
+    it "raises a TypeError if step does not respond to #to_int" do
+      obj = mock("Range#step non-integer")
 
-  it "raises a TypeError if step does not respond to #to_int" do
-    obj = mock("Range#step non-integer")
+      -> { (1..2).step(obj) { } }.should.raise(TypeError)
+    end
 
-    -> { (1..2).step(obj) { } }.should raise_error(TypeError)
-  end
+    it "raises a TypeError if #to_int does not return an Integer" do
+      obj = mock("Range#step non-integer")
+      obj.should_receive(:to_int).and_return("1")
 
-  it "raises a TypeError if #to_int does not return an Integer" do
-    obj = mock("Range#step non-integer")
-    obj.should_receive(:to_int).and_return("1")
+      -> { (1..2).step(obj) { } }.should.raise(TypeError)
+    end
 
-    -> { (1..2).step(obj) { } }.should raise_error(TypeError)
-  end
+    it "raises a TypeError if the first element does not respond to #succ" do
+      obj = mock("Range#step non-comparable")
+      obj.should_receive(:<=>).with(obj).and_return(1)
 
-  it "coerces the argument to integer by invoking to_int" do
-    (obj = mock("2")).should_receive(:to_int).and_return(2)
-    res = []
-    (1..10).step(obj) {|x| res << x}
-    res.should == [1, 3, 5, 7, 9]
+      -> { (obj..obj).step { |x| x } }.should.raise(TypeError)
+    end
   end
 
-  it "raises a TypeError if the first element does not respond to #succ" do
-    obj = mock("Range#step non-comparable")
-    obj.should_receive(:<=>).with(obj).and_return(1)
+  ruby_version_is "3.4" do
+    it "calls #coerce to coerce step to an Integer" do
+      obj = mock("Range#step")
+      obj.should_receive(:coerce).at_least(:once).and_return([1, 2])
+
+      (1..3).step(obj) { |x| ScratchPad << x }
+      ScratchPad.recorded.should.eql?([1, 3])
+    end
+
+    it "raises a TypeError if step does not respond to #coerce" do
+      obj = mock("Range#step non-coercible")
 
-    -> { (obj..obj).step { |x| x } }.should raise_error(TypeError)
+      -> { (1..2).step(obj) { } }.should.raise(TypeError)
+    end
   end
 
   it "raises an ArgumentError if step is 0" do
-    -> { (-1..1).step(0) { |x| x } }.should raise_error(ArgumentError)
+    -> { (-1..1).step(0) { |x| x } }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if step is 0.0" do
-    -> { (-1..1).step(0.0) { |x| x } }.should raise_error(ArgumentError)
+    -> { (-1..1).step(0.0) { |x| x } }.should.raise(ArgumentError)
+  end
+
+  ruby_version_is "3.4" do
+    it "does not iterate if step is 0 for bounded non-numeric ranges" do
+      t = Time.utc(2023, 2, 24)
+      (t..t + 1).step(0) { |x| ScratchPad << x }
+      ScratchPad.recorded.should == []
+    end
+
+    it "raises an ArgumentError when iterating a beginless range" do
+      -> { (..10).step(1) { break } }.should.raise(ArgumentError,
+        "#step iteration for beginless ranges is meaningless")
+    end
   end
 
-  it "raises an ArgumentError if step is negative" do
-    -> { (-1..1).step(-2) { |x| x } }.should raise_error(ArgumentError)
+  ruby_version_is ""..."3.4" do
+    it "raises an ArgumentError if step is negative" do
+      -> { (-1..1).step(-2) { |x| x } }.should.raise(ArgumentError)
+    end
   end
 
   describe "with inclusive end" do
     describe "and Integer values" do
       it "yields Integer values incremented by 1 and less than or equal to end when not passed a step" do
         (-2..2).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2, -1, 0, 1, 2])
+        ScratchPad.recorded.should.eql?([-2, -1, 0, 1, 2])
       end
 
       it "yields Integer values incremented by an Integer step" do
         (-5..5).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5, -3, -1, 1, 3, 5])
+        ScratchPad.recorded.should.eql?([-5, -3, -1, 1, 3, 5])
       end
 
       it "yields Float values incremented by a Float step" do
         (-2..2).step(1.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
+        ScratchPad.recorded.should.eql?([-2.0, -0.5, 1.0])
+      end
+
+      ruby_version_is "3.4" do
+        it "does not iterate if step is negative for forward range" do
+          (-1..1).step(-1) { |x| ScratchPad << x }
+          ScratchPad.recorded.should.eql?([])
+        end
+
+        it "iterates backward if step is negative for backward range" do
+          (1..-1).step(-1) { |x| ScratchPad << x }
+          ScratchPad.recorded.should.eql?([1, 0, -1])
+        end
       end
     end
 
     describe "and Float values" do
       it "yields Float values incremented by 1 and less than or equal to end when not passed a step" do
         (-2.0..2.0).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0, 2.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0, 2.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5.0..5.0).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
       end
 
       it "yields Float values incremented by a Float step" do
         (-1.0..1.0).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5, 1.0])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5, 1.0])
       end
 
       it "returns Float values of 'step * n + begin <= end'" do
         (1.0..6.4).step(1.8) { |x| ScratchPad << x }
         (1.0..12.7).step(1.3) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([1.0, 2.8, 4.6, 6.4, 1.0, 2.3, 3.6,
+        ScratchPad.recorded.should.eql?([1.0, 2.8, 4.6, 6.4, 1.0, 2.3, 3.6,
                                        4.9, 6.2, 7.5, 8.8, 10.1, 11.4, 12.7])
       end
 
       it "handles infinite values at either end" do
         (-Float::INFINITY..0.0).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-        ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
+        ScratchPad.recorded.should.eql?([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
 
         ScratchPad.record []
         (0.0..Float::INFINITY).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-        ScratchPad.recorded.should eql([0.0, 2.0, 4.0])
+        ScratchPad.recorded.should.eql?([0.0, 2.0, 4.0])
+      end
+
+      ruby_version_is "3.4" do
+        it "does not iterate if step is negative for forward range" do
+          (-1.0..1.0).step(-0.5) { |x| ScratchPad << x }
+          ScratchPad.recorded.should.eql?([])
+        end
+
+        it "iterates backward if step is negative for backward range" do
+          (1.0..-1.0).step(-0.5) { |x| ScratchPad << x }
+          ScratchPad.recorded.should.eql?([1.0, 0.5, 0.0, -0.5, -1.0])
+        end
       end
     end
 
     describe "and Integer, Float values" do
       it "yields Float values incremented by 1 and less than or equal to end when not passed a step" do
         (-2..2.0).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0, 2.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0, 2.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5..5.0).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
       end
 
       it "yields Float values incremented by a Float step" do
         (-1..1.0).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5, 1.0])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5, 1.0])
       end
     end
 
     describe "and Float, Integer values" do
       it "yields Float values incremented by 1 and less than or equal to end when not passed a step" do
         (-2.0..2).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0, 2.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0, 2.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5.0..5).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0, 5.0])
       end
 
       it "yields Float values incremented by a Float step" do
         (-1.0..1).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5, 1.0])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5, 1.0])
       end
     end
 
@@ -159,16 +204,99 @@ describe "Range#step" do
       end
 
       it "raises a TypeError when passed a Float step" do
-        -> { ("A".."G").step(2.0) { } }.should raise_error(TypeError)
+        -> { ("A".."G").step(2.0) { } }.should.raise(TypeError)
       end
 
-      it "calls #succ on begin and each element returned by #succ" do
-        obj = mock("Range#step String start")
-        obj.should_receive(:<=>).exactly(3).times.and_return(-1, -1, -1, 0)
-        obj.should_receive(:succ).exactly(2).times.and_return(obj)
+      ruby_version_is ""..."3.4" do
+        it "calls #succ on begin and each element returned by #succ" do
+          obj = mock("Range#step String start")
+          obj.should_receive(:<=>).exactly(3).times.and_return(-1, -1, -1, 0)
+          obj.should_receive(:succ).exactly(2).times.and_return(obj)
 
-        (obj..obj).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should == [obj, obj, obj]
+          (obj..obj).step { |x| ScratchPad << x }
+          ScratchPad.recorded.should == [obj, obj, obj]
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "yields String values adjusted by step and less than or equal to end" do
+          ("A".."AAA").step("A") { |x| ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "AA", "AAA"]
+        end
+
+        it "raises a TypeError when passed an incompatible type step" do
+          -> { ("A".."G").step([]) { } }.should.raise(TypeError)
+        end
+
+        it "calls #+ on begin and each element returned by #+" do
+          start = mock("Range#step String start")
+          stop = mock("Range#step String stop")
+
+          mid1 = mock("Range#step String mid1")
+          mid2 = mock("Range#step String mid2")
+
+          step = mock("Range#step String step")
+
+          # Deciding on the direction of iteration
+          start.should_receive(:<=>).with(stop).at_least(:twice).and_return(-1)
+          # Deciding whether the step moves iteration in the right direction
+          start.should_receive(:<=>).with(mid1).and_return(-1)
+          # Iteration 1
+          start.should_receive(:+).at_least(:once).with(step).and_return(mid1)
+          # Iteration 2
+          mid1.should_receive(:<=>).with(stop).and_return(-1)
+          mid1.should_receive(:+).with(step).and_return(mid2)
+          # Iteration 3
+          mid2.should_receive(:<=>).with(stop).and_return(0)
+
+          (start..stop).step(step) { |x| ScratchPad << x }
+          ScratchPad.recorded.should == [start, mid1, mid2]
+        end
+
+        it "iterates backward if the step is decreasing values, and the range is backward" do
+          start = mock("Range#step String start")
+          stop = mock("Range#step String stop")
+
+          mid1 = mock("Range#step String mid1")
+          mid2 = mock("Range#step String mid2")
+
+          step = mock("Range#step String step")
+
+          # Deciding on the direction of iteration
+          start.should_receive(:<=>).with(stop).at_least(:twice).and_return(1)
+          # Deciding whether the step moves iteration in the right direction
+          start.should_receive(:<=>).with(mid1).and_return(1)
+          # Iteration 1
+          start.should_receive(:+).at_least(:once).with(step).and_return(mid1)
+          # Iteration 2
+          mid1.should_receive(:<=>).with(stop).and_return(1)
+          mid1.should_receive(:+).with(step).and_return(mid2)
+          # Iteration 3
+          mid2.should_receive(:<=>).with(stop).and_return(0)
+
+          (start..stop).step(step) { |x| ScratchPad << x }
+          ScratchPad.recorded.should == [start, mid1, mid2]
+        end
+
+        it "does no iteration of the direction of the range and of the step don't match" do
+          start = mock("Range#step String start")
+          stop = mock("Range#step String stop")
+
+          mid1 = mock("Range#step String mid1")
+          mid2 = mock("Range#step String mid2")
+
+          step = mock("Range#step String step")
+
+          # Deciding on the direction of iteration: stop > start
+          start.should_receive(:<=>).with(stop).at_least(:twice).and_return(1)
+          # Deciding whether the step moves iteration in the right direction
+          # start + step < start, the direction is opposite to the range's
+          start.should_receive(:+).with(step).and_return(mid1)
+          start.should_receive(:<=>).with(mid1).and_return(-1)
+
+          (start..stop).step(step) { |x| ScratchPad << x }
+          ScratchPad.recorded.should == []
+        end
       end
     end
   end
@@ -177,141 +305,270 @@ describe "Range#step" do
     describe "and Integer values" do
       it "yields Integer values incremented by 1 and less than end when not passed a step" do
         (-2...2).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2, -1, 0, 1])
+        ScratchPad.recorded.should.eql?([-2, -1, 0, 1])
       end
 
       it "yields Integer values incremented by an Integer step" do
         (-5...5).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5, -3, -1, 1, 3])
+        ScratchPad.recorded.should.eql?([-5, -3, -1, 1, 3])
       end
 
       it "yields Float values incremented by a Float step" do
         (-2...2).step(1.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
+        ScratchPad.recorded.should.eql?([-2.0, -0.5, 1.0])
       end
     end
 
     describe "and Float values" do
       it "yields Float values incremented by 1 and less than end when not passed a step" do
         (-2.0...2.0).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5.0...5.0).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0])
       end
 
       it "yields Float values incremented by a Float step" do
         (-1.0...1.0).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5])
       end
 
       it "returns Float values of 'step * n + begin < end'" do
         (1.0...6.4).step(1.8) { |x| ScratchPad << x }
+        ScratchPad.recorded.should.eql?([1.0, 2.8, 4.6])
+      end
+
+      it "correctly handles values near the upper limit" do # https://bugs.ruby-lang.org/issues/16612
         (1.0...55.6).step(18.2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([1.0, 2.8, 4.6, 1.0, 19.2, 37.4])
+        ScratchPad.recorded.should.eql?([1.0, 19.2, 37.4, 55.599999999999994])
+
+        (1.0...55.6).step(18.2).size.should == 4
       end
 
       it "handles infinite values at either end" do
         (-Float::INFINITY...0.0).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-        ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
+        ScratchPad.recorded.should.eql?([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
 
         ScratchPad.record []
         (0.0...Float::INFINITY).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-        ScratchPad.recorded.should eql([0.0, 2.0, 4.0])
+        ScratchPad.recorded.should.eql?([0.0, 2.0, 4.0])
+      end
+
+      ruby_version_is "3.4" do
+        it "iterates backward with exclusive end if step is negative" do
+          (1.0...-1.0).step(-0.5) { |x| ScratchPad << x }
+          ScratchPad.recorded.should.eql?([1.0, 0.5, 0.0, -0.5])
+        end
       end
     end
 
     describe "and Integer, Float values" do
       it "yields Float values incremented by 1 and less than end when not passed a step" do
         (-2...2.0).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5...5.0).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0])
       end
 
       it "yields an Float and then Float values incremented by a Float step" do
         (-1...1.0).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5])
       end
     end
 
     describe "and Float, Integer values" do
       it "yields Float values incremented by 1 and less than end when not passed a step" do
         (-2.0...2).step { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0])
       end
 
       it "yields Float values incremented by an Integer step" do
         (-5.0...5).step(2) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0])
       end
 
       it "yields Float values incremented by a Float step" do
         (-1.0...1).step(0.5) { |x| ScratchPad << x }
-        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5])
+      end
+    end
+
+    describe "and String values" do
+      ruby_version_is ""..."3.4" do
+        it "yields String values incremented by #succ and less than or equal to end when not passed a step" do
+          ("A"..."E").step { |x| ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "B", "C", "D"]
+        end
+
+        it "yields String values incremented by #succ called Integer step times" do
+          ("A"..."G").step(2) { |x| ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "C", "E"]
+        end
+
+        it "raises a TypeError when passed a Float step" do
+          -> { ("A"..."G").step(2.0) { } }.should.raise(TypeError)
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "yields String values adjusted by step and less than or equal to end" do
+          ("A"..."AAA").step("A") { |x| ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "AA"]
+        end
+
+        it "raises a TypeError when passed an incompatible type step" do
+          -> { ("A".."G").step([]) { } }.should.raise(TypeError)
+        end
+      end
+    end
+  end
+
+  describe "with an endless range" do
+    describe "and Integer values" do
+      it "yield Integer values incremented by 1 when not passed a step" do
+        (-2..).step { |x| break if x > 2; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2, -1, 0, 1, 2])
+
+        ScratchPad.record []
+        (-2...).step { |x| break if x > 2; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2, -1, 0, 1, 2])
+      end
+
+      it "yields Integer values incremented by an Integer step" do
+        (-5..).step(2) { |x| break if x > 3; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-5, -3, -1, 1, 3])
+
+        ScratchPad.record []
+        (-5...).step(2) { |x| break if x > 3; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-5, -3, -1, 1, 3])
+      end
+
+      it "yields Float values incremented by a Float step" do
+        (-2..).step(1.5) { |x| break if x > 1.0; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2.0, -0.5, 1.0])
+
+        ScratchPad.record []
+        (-2..).step(1.5) { |x| break if x > 1.0; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2.0, -0.5, 1.0])
+      end
+    end
+
+    describe "and Float values" do
+      it "yields Float values incremented by 1 and less than end when not passed a step" do
+        (-2.0..).step { |x| break if x > 1.5; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0])
+
+        ScratchPad.record []
+        (-2.0...).step { |x| break if x > 1.5; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-2.0, -1.0, 0.0, 1.0])
+      end
+
+      it "yields Float values incremented by an Integer step" do
+        (-5.0..).step(2) { |x| break if x > 3.5; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0])
+
+        ScratchPad.record []
+        (-5.0...).step(2) { |x| break if x > 3.5; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-5.0, -3.0, -1.0, 1.0, 3.0])
+      end
+
+      it "yields Float values incremented by a Float step" do
+        (-1.0..).step(0.5) { |x| break if x > 0.6; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5])
+
+        ScratchPad.record []
+        (-1.0...).step(0.5) { |x| break if x > 0.6; ScratchPad << x }
+        ScratchPad.recorded.should.eql?([-1.0, -0.5, 0.0, 0.5])
+      end
+
+      it "computes each value independently to avoid accumulating floating-point errors" do
+        result = []
+        (0.0..).step(0.1) { |x| result << x; break if result.size == 20 }
+        expected = 20.times.map { |i| i * 0.1 + 0.0 }
+        result.should.eql?(expected)
+      end
+
+      it "handles infinite values at the start" do
+        (-Float::INFINITY..).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
+        ScratchPad.recorded.should.eql?([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
+
+        ScratchPad.record []
+        (-Float::INFINITY...).step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
+        ScratchPad.recorded.should.eql?([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
       end
     end
 
     describe "and String values" do
       it "yields String values incremented by #succ and less than or equal to end when not passed a step" do
-        ("A"..."E").step { |x| ScratchPad << x }
+        ('A'..).step { |x| break if x > "D"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "B", "C", "D"]
+
+        ScratchPad.record []
+        ('A'...).step { |x| break if x > "D"; ScratchPad << x }
         ScratchPad.recorded.should == ["A", "B", "C", "D"]
       end
 
       it "yields String values incremented by #succ called Integer step times" do
-        ("A"..."G").step(2) { |x| ScratchPad << x }
+        ('A'..).step(2) { |x| break if x > "F"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "C", "E"]
+
+        ScratchPad.record []
+        ('A'...).step(2) { |x| break if x > "F"; ScratchPad << x }
         ScratchPad.recorded.should == ["A", "C", "E"]
       end
 
       it "raises a TypeError when passed a Float step" do
-        -> { ("A"..."G").step(2.0) { } }.should raise_error(TypeError)
+        -> { ('A'..).step(2.0) { } }.should.raise(TypeError)
+        -> { ('A'...).step(2.0) { } }.should.raise(TypeError)
       end
-    end
-  end
 
-  describe "when no block is given" do
-    describe "returned Enumerator" do
-      describe "size" do
-        it "raises a TypeError if step does not respond to #to_int" do
-          obj = mock("Range#step non-integer")
-          enum = (1..2).step(obj)
-          -> { enum.size }.should raise_error(TypeError)
-        end
+      ruby_version_is "3.4" do
+        it "yields String values adjusted by step" do
+          ('A'..).step("A") { |x| break if x > "AAA"; ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "AA", "AAA"]
 
-        it "raises a TypeError if #to_int does not return an Integer" do
-          obj = mock("Range#step non-integer")
-          obj.should_receive(:to_int).and_return("1")
-          enum = (1..2).step(obj)
+          ScratchPad.record []
+          ('A'...).step("A") { |x| break if x > "AAA"; ScratchPad << x }
+          ScratchPad.recorded.should == ["A", "AA", "AAA"]
+        end
 
-          -> { enum.size }.should raise_error(TypeError)
+        it "raises a TypeError when passed an incompatible type step" do
+          -> { ('A'..).step([]) { } }.should.raise(TypeError)
+          -> { ('A'...).step([]) { } }.should.raise(TypeError)
         end
+      end
+    end
+  end
 
-        ruby_version_is ""..."2.6" do
-          it "raises an ArgumentError if step is 0" do
-            enum = (-1..1).step(0)
-            -> { enum.size }.should raise_error(ArgumentError)
-          end
+  describe "when no block is given" do
+    it "raises an ArgumentError if step is 0" do
+      -> { (-1..1).step(0) }.should.raise(ArgumentError)
+    end
 
-          it "raises an ArgumentError if step is 0.0" do
-            enum = (-1..1).step(0.0)
-            -> { enum.size }.should raise_error(ArgumentError)
+    describe "returned Enumerator" do
+      describe "size" do
+        ruby_version_is ""..."3.4" do
+          it "raises a TypeError if step does not respond to #to_int" do
+            obj = mock("Range#step non-integer")
+            -> { (1..2).step(obj) }.should.raise(TypeError)
           end
 
-          it "raises an ArgumentError if step is negative" do
-            enum = (-1..1).step(-2)
-            -> {  enum.size }.should raise_error(ArgumentError)
+          it "raises a TypeError if #to_int does not return an Integer" do
+            obj = mock("Range#step non-integer")
+            obj.should_receive(:to_int).and_return("1")
+            -> { (1..2).step(obj) }.should.raise(TypeError)
           end
         end
 
-        ruby_version_is "2.6" do
-          it "returns Float::INFINITY for zero step" do
-            (-1..1).step(0).size.should == Float::INFINITY
-            (-1..1).step(0.0).size.should == Float::INFINITY
+        ruby_version_is "3.4" do
+          it "does not raise if step is incompatible" do
+            obj = mock("Range#step non-integer")
+            -> { (1..2).step(obj) }.should_not.raise
           end
         end
 
@@ -328,11 +585,9 @@ describe "Range#step" do
           (-5...5).step(2).size.should == 5
         end
 
-        ruby_version_is "2.6" do
-          it "returns the ceil of range size divided by the number of steps even if step is negative" do
-            (-1..1).step(-1).size.should == 0
-            (1..-1).step(-1).size.should == 3
-          end
+        it "returns the ceil of range size divided by the number of steps even if step is negative" do
+          (-1..1).step(-1).size.should == 0
+          (1..-1).step(-1).size.should == 3
         end
 
         it "returns the correct number of steps when one of the arguments is a float" do
@@ -352,42 +607,115 @@ describe "Range#step" do
           (-2...2.0).step.size.should == 4
           (-2.0...2).step.size.should == 4
           (1.0...6.4).step(1.8).size.should == 3
-          (1.0...55.6).step(18.2).size.should == 3
         end
 
-        it "returns nil with begin and end are String" do
-          ("A".."E").step(2).size.should == nil
-          ("A"..."E").step(2).size.should == nil
-          ("A".."E").step.size.should == nil
-          ("A"..."E").step.size.should == nil
+        ruby_version_is ""..."3.4" do
+          it "returns nil with begin and end are String" do
+            ("A".."E").step(2).size.should == nil
+            ("A"..."E").step(2).size.should == nil
+            ("A".."E").step.size.should == nil
+            ("A"..."E").step.size.should == nil
+          end
+
+          it "return nil and not raises a TypeError if the first element does not respond to #succ" do
+            obj = mock("Range#step non-comparable")
+            obj.should_receive(:<=>).with(obj).and_return(1)
+            enum = (obj..obj).step
+            -> { enum.size }.should_not.raise
+            enum.size.should == nil
+          end
         end
 
-        it "return nil and not raises a TypeError if the first element does not respond to #succ" do
-          obj = mock("Range#step non-comparable")
-          obj.should_receive(:<=>).with(obj).and_return(1)
-          enum = (obj..obj).step
-          -> { enum.size }.should_not raise_error
-          enum.size.should == nil
+        ruby_version_is "3.4" do
+          it "returns nil with begin and end are String" do
+            ("A".."E").step("A").size.should == nil
+            ("A"..."E").step("A").size.should == nil
+          end
+
+          it "return nil and not raises a TypeError if the first element is not of compatible type" do
+            obj = mock("Range#step non-comparable")
+            obj.should_receive(:<=>).with(obj).and_return(1)
+            enum = (obj..obj).step(obj)
+            -> { enum.size }.should_not.raise
+            enum.size.should == nil
+          end
         end
       end
 
+      # We use .take below to ensure the enumerator works
+      # because that's an Enumerable method and so it uses the Enumerator behavior
+      # not just a method overridden in Enumerator::ArithmeticSequence.
       describe "type" do
-        ruby_version_is ""..."2.6" do
-          it "returns an instance of Enumerator" do
-            (1..10).step.class.should == Enumerator
+        context "when both begin and end are numerics" do
+          it "returns an instance of Enumerator::ArithmeticSequence" do
+            (1..10).step.class.should == Enumerator::ArithmeticSequence
+            (1..10).step(3).take(4).should == [1, 4, 7, 10]
+          end
+        end
+
+        context "when begin is not defined and end is numeric" do
+          it "returns an instance of Enumerator::ArithmeticSequence" do
+            (..10).step.class.should == Enumerator::ArithmeticSequence
           end
         end
 
-        ruby_version_is "2.6" do
-          context "when both begin and end are numerics" do
-            it "returns an instance of Enumerator::ArithmeticSequence" do
-              (1..10).step.class.should == Enumerator::ArithmeticSequence
+        context "when range is endless" do
+          it "returns an instance of Enumerator::ArithmeticSequence when begin is numeric" do
+            (1..).step.class.should == Enumerator::ArithmeticSequence
+            (1..).step(2).take(3).should == [1, 3, 5]
+          end
+
+          ruby_version_is ""..."3.4" do
+            it "returns an instance of Enumerator when begin is not numeric" do
+              ("a"..).step.class.should == Enumerator
+              ("a"..).step(2).take(3).should == %w[a c e]
             end
           end
 
-          context "when begin and end are not numerics" do
+          ruby_version_is "3.4" do
+            it "returns an instance of Enumerator when begin is not numeric" do
+              ("a"..).step("a").class.should == Enumerator
+              ("a"..).step("a").take(3).should == %w[a aa aaa]
+            end
+          end
+        end
+
+        context "when range is beginless and endless" do
+          ruby_version_is ""..."3.4" do
+            it "returns an instance of Enumerator" do
+              Range.new(nil, nil).step.class.should == Enumerator
+            end
+          end
+
+          ruby_version_is "3.4" do
+            it "raises an ArgumentError" do
+              -> { Range.new(nil, nil).step(1) }.should.raise(ArgumentError,
+                "#step for non-numeric beginless ranges is meaningless")
+            end
+          end
+        end
+
+        context "when range is beginless and finite" do
+          ruby_version_is "3.4" do
+            it "raises an ArgumentError if step is non-numeric" do
+              -> { (..10).step("a") }.should.raise(ArgumentError,
+                "#step for non-numeric beginless ranges is meaningless")
+            end
+          end
+        end
+
+        context "when begin and end are not numerics" do
+          ruby_version_is ""..."3.4" do
             it "returns an instance of Enumerator" do
               ("a".."z").step.class.should == Enumerator
+              ("a".."z").step(3).take(4).should == %w[a d g j]
+            end
+          end
+
+          ruby_version_is "3.4" do
+            it "returns an instance of Enumerator" do
+              ("a".."z").step("a").class.should == Enumerator
+              ("a".."z").step("a").take(4).should == %w[a aa aaa aaaa]
             end
           end
         end
diff --git a/spec/ruby/core/range/to_a_spec.rb b/spec/ruby/core/range/to_a_spec.rb
index 15f0b44a9c..6221ae5f71 100644
--- a/spec/ruby/core/range/to_a_spec.rb
+++ b/spec/ruby/core/range/to_a_spec.rb
@@ -6,7 +6,7 @@ describe "Range#to_a" do
     ('A'..'D').to_a.should == ['A','B','C','D']
     ('A'...'D').to_a.should == ['A','B','C']
     (0xfffd...0xffff).to_a.should == [0xfffd,0xfffe]
-    -> { (0.5..2.4).to_a }.should raise_error(TypeError)
+    -> { (0.5..2.4).to_a }.should.raise(TypeError)
   end
 
   it "returns empty array for descending-ordered" do
@@ -16,7 +16,24 @@ describe "Range#to_a" do
     (0xffff...0xfffd).to_a.should == []
   end
 
+  it "works with Ranges of 64-bit integers" do
+    large = 1 << 40
+    (large..large+1).to_a.should == [1099511627776, 1099511627777]
+  end
+
   it "works with Ranges of Symbols" do
     (:A..:z).to_a.size.should == 58
   end
+
+  it "works for non-ASCII ranges" do
+    ('Σ'..'Ω').to_a.should == ["Σ", "Τ", "Υ", "Φ", "Χ", "Ψ", "Ω"]
+  end
+
+  it "throws an exception for endless ranges" do
+    -> { eval("(1..)").to_a }.should.raise(RangeError)
+  end
+
+  it "throws an exception for beginless ranges" do
+    -> { (..1).to_a }.should.raise(TypeError)
+  end
 end
diff --git a/spec/ruby/core/range/to_s_spec.rb b/spec/ruby/core/range/to_s_spec.rb
index 4c37e81fe0..460c330912 100644
--- a/spec/ruby/core/range/to_s_spec.rb
+++ b/spec/ruby/core/range/to_s_spec.rb
@@ -11,15 +11,13 @@ describe "Range#to_s" do
     (0.5..2.4).to_s.should == "0.5..2.4"
   end
 
-  it "returns a tainted string if either end is tainted" do
-    (("a".taint)..."c").to_s.tainted?.should be_true
-    ("a"...("c".taint)).to_s.tainted?.should be_true
-    ("a"..."c").taint.to_s.tainted?.should be_true
+  it "can show endless ranges" do
+    eval("(1..)").to_s.should == "1.."
+    eval("(1.0...)").to_s.should == "1.0..."
   end
 
-  it "returns a untrusted string if either end is untrusted" do
-    (("a".untrust)..."c").to_s.untrusted?.should be_true
-    ("a"...("c".untrust)).to_s.untrusted?.should be_true
-    ("a"..."c").untrust.to_s.untrusted?.should be_true
+  it "can show beginless ranges" do
+    (..1).to_s.should == "..1"
+    (...1.0).to_s.should == "...1.0"
   end
 end
diff --git a/spec/ruby/core/range/to_set_spec.rb b/spec/ruby/core/range/to_set_spec.rb
new file mode 100644
index 0000000000..ac81d2cc4b
--- /dev/null
+++ b/spec/ruby/core/range/to_set_spec.rb
@@ -0,0 +1,54 @@
+require_relative '../../spec_helper'
+require_relative '../enumerable/fixtures/classes'
+
+describe "Range#to_set" do
+  it "returns a new Set created from self" do
+    (1..4).to_set.should == Set[1, 2, 3, 4]
+    (1...4).to_set.should == Set[1, 2, 3]
+  end
+
+  it "passes down passed blocks" do
+    (1..3).to_set { |x| x * x }.should == Set[1, 4, 9]
+  end
+
+  it "raises a TypeError for a beginningless range" do
+    -> {
+      (..0).to_set
+    }.should.raise(TypeError, "can't iterate from NilClass")
+  end
+
+  ruby_version_is "4.0" do
+    it "raises a RangeError if the range is endless" do
+      -> { (1..).to_set }.should.raise(RangeError, "cannot convert endless range to a set")
+      -> { (1...).to_set }.should.raise(RangeError, "cannot convert endless range to a set")
+    end
+  end
+
+  context "given positional arguments" do
+    ruby_version_is ""..."4.0" do
+      it "instantiates an object of provided as the first argument set class" do
+        set = (1..3).to_set(EnumerableSpecs::SetSubclass)
+        set.should.is_a?(EnumerableSpecs::SetSubclass)
+        set.to_a.sort.should == [1, 2, 3]
+      end
+    end
+
+    ruby_version_is "4.0"..."4.1" do
+      it "instantiates an object of provided as the first argument set class and warns" do
+        -> {
+          set = (1..3).to_set(EnumerableSpecs::SetSubclass)
+          set.should.is_a?(EnumerableSpecs::SetSubclass)
+          set.to_a.sort.should == [1, 2, 3]
+        }.should complain(/warning: passing arguments to Enumerable#to_set is deprecated/)
+      end
+    end
+
+    ruby_version_is "4.1" do
+      it "does not accept any positional argument" do
+        -> {
+          (1..3).to_set(EnumerableSpecs::SetSubclass)
+        }.should.raise(ArgumentError, "wrong number of arguments (given 1, expected 0)")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/rational/abs_spec.rb b/spec/ruby/core/rational/abs_spec.rb
index aed7713058..54099aa14d 100644
--- a/spec/ruby/core/rational/abs_spec.rb
+++ b/spec/ruby/core/rational/abs_spec.rb
@@ -1,4 +1,5 @@
-require_relative '../../shared/rational/abs'
+require_relative "../../spec_helper"
+require_relative 'shared/abs'
 
 describe "Rational#abs" do
   it_behaves_like :rational_abs, :abs
diff --git a/spec/ruby/core/rational/ceil_spec.rb b/spec/ruby/core/rational/ceil_spec.rb
index 5b0ca4a9d6..0464eab101 100644
--- a/spec/ruby/core/rational/ceil_spec.rb
+++ b/spec/ruby/core/rational/ceil_spec.rb
@@ -1,5 +1,48 @@
-require_relative '../../shared/rational/ceil'
+require_relative "../../spec_helper"
+require_relative "../integer/shared/integer_ceil_precision"
 
 describe "Rational#ceil" do
-  it_behaves_like :rational_ceil, :ceil
+  context "with values equal to integers" do
+    it_behaves_like :integer_ceil_precision, :Rational
+  end
+
+  before do
+    @rational = Rational(2200, 7)
+  end
+
+  describe "with no arguments (precision = 0)" do
+    it "returns the Integer value rounded toward positive infinity" do
+      @rational.ceil.should.eql? 315
+
+      Rational(1, 2).ceil.should.eql? 1
+      Rational(-1, 2).ceil.should.eql? 0
+      Rational(1, 1).ceil.should.eql? 1
+    end
+  end
+
+  describe "with a precision < 0" do
+    it "moves the rounding point n decimal places left, returning an Integer" do
+      @rational.ceil(-3).should.eql? 1000
+      @rational.ceil(-2).should.eql? 400
+      @rational.ceil(-1).should.eql? 320
+
+      Rational(100, 2).ceil(-1).should.eql? 50
+      Rational(100, 2).ceil(-2).should.eql? 100
+      Rational(-100, 2).ceil(-1).should.eql?(-50)
+      Rational(-100, 2).ceil(-2).should.eql?(0)
+    end
+  end
+
+  describe "with precision > 0" do
+    it "moves the rounding point n decimal places right, returning a Rational" do
+      @rational.ceil(1).should.eql? Rational(3143, 10)
+      @rational.ceil(2).should.eql? Rational(31429, 100)
+      @rational.ceil(3).should.eql? Rational(157143, 500)
+
+      Rational(100, 2).ceil(1).should.eql? Rational(50, 1)
+      Rational(100, 2).ceil(2).should.eql? Rational(50, 1)
+      Rational(-100, 2).ceil(1).should.eql? Rational(-50, 1)
+      Rational(-100, 2).ceil(2).should.eql? Rational(-50, 1)
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/coerce_spec.rb b/spec/ruby/core/rational/coerce_spec.rb
deleted file mode 100644
index 3f78f0bcd6..0000000000
--- a/spec/ruby/core/rational/coerce_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative '../../shared/rational/coerce'
-
-describe "Rational#coerce" do
-  it_behaves_like :rational_coerce, :coerce
-end
diff --git a/spec/ruby/core/rational/comparison_spec.rb b/spec/ruby/core/rational/comparison_spec.rb
index b2784f3e7d..482e904989 100644
--- a/spec/ruby/core/rational/comparison_spec.rb
+++ b/spec/ruby/core/rational/comparison_spec.rb
@@ -1,22 +1,93 @@
-require_relative '../../shared/rational/comparison'
+require_relative "../../spec_helper"
+require_relative 'fixtures/rational'
 
 describe "Rational#<=> when passed a Rational object" do
-  it_behaves_like :rational_cmp_rat, :<=>
+  it "returns 1 when self is greater than the passed argument" do
+    (Rational(4, 4) <=> Rational(3, 4)).should.equal?(1)
+    (Rational(-3, 4) <=> Rational(-4, 4)).should.equal?(1)
+  end
+
+  it "returns 0 when self is equal to the passed argument" do
+    (Rational(4, 4) <=> Rational(4, 4)).should.equal?(0)
+    (Rational(-3, 4) <=> Rational(-3, 4)).should.equal?(0)
+  end
+
+  it "returns -1 when self is less than the passed argument" do
+    (Rational(3, 4) <=> Rational(4, 4)).should.equal?(-1)
+    (Rational(-4, 4) <=> Rational(-3, 4)).should.equal?(-1)
+  end
 end
 
-describe "Rational#<=> when passed a Integer object" do
-  it_behaves_like :rational_cmp_int, :<=>
+describe "Rational#<=> when passed an Integer object" do
+  it "returns 1 when self is greater than the passed argument" do
+    (Rational(4, 4) <=> 0).should.equal?(1)
+    (Rational(4, 4) <=> -10).should.equal?(1)
+    (Rational(-3, 4) <=> -1).should.equal?(1)
+  end
+
+  it "returns 0 when self is equal to the passed argument" do
+    (Rational(4, 4) <=> 1).should.equal?(0)
+    (Rational(-8, 4) <=> -2).should.equal?(0)
+  end
+
+  it "returns -1 when self is less than the passed argument" do
+    (Rational(3, 4) <=> 1).should.equal?(-1)
+    (Rational(-4, 4) <=> 0).should.equal?(-1)
+  end
 end
 
 describe "Rational#<=> when passed a Float object" do
-  it_behaves_like :rational_cmp_float, :<=>
+  it "returns 1 when self is greater than the passed argument" do
+    (Rational(4, 4) <=> 0.5).should.equal?(1)
+    (Rational(4, 4) <=> -1.5).should.equal?(1)
+    (Rational(-3, 4) <=> -0.8).should.equal?(1)
+  end
+
+  it "returns 0 when self is equal to the passed argument" do
+    (Rational(4, 4) <=> 1.0).should.equal?(0)
+    (Rational(-6, 4) <=> -1.5).should.equal?(0)
+  end
+
+  it "returns -1 when self is less than the passed argument" do
+    (Rational(3, 4) <=> 1.2).should.equal?(-1)
+    (Rational(-4, 4) <=> 0.5).should.equal?(-1)
+  end
 end
 
 describe "Rational#<=> when passed an Object that responds to #coerce" do
-  it_behaves_like :rational_cmp_coerce, :<=>
-  it_behaves_like :rational_cmp_coerce_exception, :<=>
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational <=> obj
+  end
+
+  it "calls #<=> on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:<=>).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational <=> obj).should == :result
+  end
+
+  it "does not rescue exception raised in other#coerce" do
+    b = mock("numeric with failed #coerce")
+    b.should_receive(:coerce).and_raise(RationalSpecs::CoerceError)
+
+    -> { Rational(3, 4) <=> b }.should.raise(RationalSpecs::CoerceError)
+  end
 end
 
 describe "Rational#<=> when passed a non-Numeric Object that doesn't respond to #coerce" do
-  it_behaves_like :rational_cmp_other, :<=>
+  it "returns nil" do
+    (Rational <=> mock("Object")).should == nil
+  end
 end
diff --git a/spec/ruby/core/rational/denominator_spec.rb b/spec/ruby/core/rational/denominator_spec.rb
index 6214b40587..ba6e936d60 100644
--- a/spec/ruby/core/rational/denominator_spec.rb
+++ b/spec/ruby/core/rational/denominator_spec.rb
@@ -1,5 +1,14 @@
-require_relative '../../shared/rational/denominator'
+require_relative "../../spec_helper"
 
 describe "Rational#denominator" do
-  it_behaves_like :rational_denominator, :denominator
+  it "returns the denominator" do
+    Rational(3, 4).denominator.should.equal?(4)
+    Rational(3, -4).denominator.should.equal?(4)
+
+    Rational(1, bignum_value).denominator.should == bignum_value
+  end
+
+  it "returns 1 if no denominator was given" do
+    Rational(80).denominator.should == 1
+  end
 end
diff --git a/spec/ruby/core/rational/div_spec.rb b/spec/ruby/core/rational/div_spec.rb
index 1cd8606b90..a679663543 100644
--- a/spec/ruby/core/rational/div_spec.rb
+++ b/spec/ruby/core/rational/div_spec.rb
@@ -1,17 +1,54 @@
-require_relative '../../shared/rational/div'
+require_relative "../../spec_helper"
 
 describe "Rational#div" do
-  it_behaves_like :rational_div, :div
+  it "returns an Integer" do
+    Rational(229, 21).div(82).should.is_a?(Integer)
+  end
+
+  it "raises an ArgumentError if passed more than one argument" do
+    -> { Rational(3, 4).div(2,3) }.should.raise(ArgumentError)
+  end
+
+  # See http://redmine.ruby-lang.org/issues/show/1648
+  it "raises a TypeError if passed a non-numeric argument" do
+    -> { Rational(3, 4).div([]) }.should.raise(TypeError)
+  end
 end
 
 describe "Rational#div passed a Rational" do
-  it_behaves_like :rational_div_rat, :div
+  it "performs integer division and returns the result" do
+    Rational(2, 3).div(Rational(2, 3)).should == 1
+    Rational(-2, 9).div(Rational(-9, 2)).should == 0
+  end
+
+  it "raises a ZeroDivisionError when the argument has a numerator of 0" do
+    -> { Rational(3, 4).div(Rational(0, 3)) }.should.raise(ZeroDivisionError)
+  end
+
+  it "raises a ZeroDivisionError when the argument has a numerator of 0.0" do
+    -> { Rational(3, 4).div(Rational(0.0, 3)) }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#div passed an Integer" do
-  it_behaves_like :rational_div_int, :div
+  it "performs integer division and returns the result" do
+    Rational(2, 1).div(1).should == 2
+    Rational(25, 5).div(-50).should == -1
+  end
+
+  it "raises a ZeroDivisionError when the argument is 0" do
+    -> { Rational(3, 4).div(0) }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#div passed a Float" do
-  it_behaves_like :rational_div_float, :div
+  it "performs integer division and returns the result" do
+    Rational(2, 3).div(30.333).should == 0
+    Rational(2, 9).div(Rational(-8.6)).should == -1
+    Rational(3.12).div(0.5).should == 6
+  end
+
+  it "raises a ZeroDivisionError when the argument is 0.0" do
+    -> { Rational(3, 4).div(0.0) }.should.raise(ZeroDivisionError)
+  end
 end
diff --git a/spec/ruby/core/rational/divide_spec.rb b/spec/ruby/core/rational/divide_spec.rb
index d8e3a44dc2..c45d1fca2f 100644
--- a/spec/ruby/core/rational/divide_spec.rb
+++ b/spec/ruby/core/rational/divide_spec.rb
@@ -1,19 +1,74 @@
-require_relative '../../shared/rational/divide'
-require_relative '../../shared/rational/arithmetic_exception_in_coerce'
+require_relative "../../spec_helper"
+require_relative 'shared/arithmetic_exception_in_coerce'
 
 describe "Rational#/" do
-  it_behaves_like :rational_divide, :/
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational / obj
+  end
+
+  it "calls #/ on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:/).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational / obj).should == :result
+  end
+
   it_behaves_like :rational_arithmetic_exception_in_coerce, :/
 end
 
 describe "Rational#/ when passed an Integer" do
-  it_behaves_like :rational_divide_int, :/
+  it "returns self divided by other as a Rational" do
+    (Rational(3, 4) / 2).should.eql?(Rational(3, 8))
+    (Rational(2, 4) / 2).should.eql?(Rational(1, 4))
+    (Rational(6, 7) / -2).should.eql?(Rational(-3, 7))
+  end
+
+  it "raises a ZeroDivisionError when passed 0" do
+    -> { Rational(3, 4) / 0 }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#/ when passed a Rational" do
-  it_behaves_like :rational_divide_rat, :/
+  it "returns self divided by other as a Rational" do
+    (Rational(3, 4) / Rational(3, 4)).should.eql?(Rational(1, 1))
+    (Rational(2, 4) / Rational(1, 4)).should.eql?(Rational(2, 1))
+
+    (Rational(2, 4) / 2).should == Rational(1, 4)
+    (Rational(6, 7) / -2).should == Rational(-3, 7)
+  end
+
+  it "raises a ZeroDivisionError when passed a Rational with a numerator of 0" do
+    -> { Rational(3, 4) / Rational(0, 1) }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#/ when passed a Float" do
-  it_behaves_like :rational_divide_float, :/
+  it "returns self divided by other as a Float" do
+    (Rational(3, 4) / 0.75).should.eql?(1.0)
+    (Rational(3, 4) / 0.25).should.eql?(3.0)
+    (Rational(3, 4) / 0.3).should.eql?(2.5)
+
+    (Rational(-3, 4) / 0.3).should.eql?(-2.5)
+    (Rational(3, -4) / 0.3).should.eql?(-2.5)
+    (Rational(3, 4) / -0.3).should.eql?(-2.5)
+  end
+
+  it "returns infinity when passed 0" do
+    (Rational(3, 4) / 0.0).infinite?.should.eql?(1)
+    (Rational(-3, -4) / 0.0).infinite?.should.eql?(1)
+
+    (Rational(-3, 4) / 0.0).infinite?.should.eql?(-1)
+    (Rational(3, -4) / 0.0).infinite?.should.eql?(-1)
+  end
 end
diff --git a/spec/ruby/core/rational/divmod_spec.rb b/spec/ruby/core/rational/divmod_spec.rb
index 6be1f8bd73..68f8ecfd2d 100644
--- a/spec/ruby/core/rational/divmod_spec.rb
+++ b/spec/ruby/core/rational/divmod_spec.rb
@@ -1,13 +1,42 @@
-require_relative '../../shared/rational/divmod'
+require_relative "../../spec_helper"
 
 describe "Rational#divmod when passed a Rational" do
-  it_behaves_like :rational_divmod_rat, :divmod
+  it "returns the quotient as Integer and the remainder as Rational" do
+    Rational(7, 4).divmod(Rational(1, 2)).should.eql?([3, Rational(1, 4)])
+    Rational(7, 4).divmod(Rational(-1, 2)).should.eql?([-4, Rational(-1, 4)])
+    Rational(0, 4).divmod(Rational(4, 3)).should.eql?([0, Rational(0, 1)])
+
+    Rational(bignum_value, 4).divmod(Rational(4, 3)).should.eql?([3458764513820540928, Rational(0, 1)])
+  end
+
+  it "raises a ZeroDivisionError when passed a Rational with a numerator of 0" do
+    -> { Rational(7, 4).divmod(Rational(0, 3)) }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#divmod when passed an Integer" do
-  it_behaves_like :rational_divmod_int, :divmod
+  it "returns the quotient as Integer and the remainder as Rational" do
+    Rational(7, 4).divmod(2).should.eql?([0, Rational(7, 4)])
+    Rational(7, 4).divmod(-2).should.eql?([-1, Rational(-1, 4)])
+
+    Rational(bignum_value, 4).divmod(3).should.eql?([1537228672809129301, Rational(1, 1)])
+  end
+
+  it "raises a ZeroDivisionError when passed 0" do
+    -> { Rational(7, 4).divmod(0) }.should.raise(ZeroDivisionError)
+  end
 end
 
 describe "Rational#divmod when passed a Float" do
-  it_behaves_like :rational_divmod_float, :divmod
+  it "returns the quotient as Integer and the remainder as Float" do
+    Rational(7, 4).divmod(0.5).should.eql?([3, 0.25])
+  end
+
+  it "returns the quotient as Integer and the remainder as Float" do
+    Rational(7, 4).divmod(-0.5).should.eql?([-4, -0.25])
+  end
+
+  it "raises a ZeroDivisionError when passed 0" do
+    -> { Rational(7, 4).divmod(0.0) }.should.raise(ZeroDivisionError)
+  end
 end
diff --git a/spec/ruby/core/rational/equal_value_spec.rb b/spec/ruby/core/rational/equal_value_spec.rb
index 8e7acb1354..1dd077ea41 100644
--- a/spec/ruby/core/rational/equal_value_spec.rb
+++ b/spec/ruby/core/rational/equal_value_spec.rb
@@ -1,17 +1,39 @@
-require_relative '../../shared/rational/equal_value'
+require_relative "../../spec_helper"
 
 describe "Rational#==" do
-  it_behaves_like :rational_equal_value, :==
+  it "returns the result of calling #== with self on the passed argument" do
+    obj = mock("Object")
+    obj.should_receive(:==).and_return(:result)
+
+    (Rational(3, 4) == obj).should_not == false
+  end
 end
 
 describe "Rational#== when passed a Rational" do
-  it_behaves_like :rational_equal_value_rat, :==
+  it "returns true if self has the same numerator and denominator as the passed argument" do
+    (Rational(3, 4) == Rational(3, 4)).should == true
+    (Rational(-3, -4) == Rational(3, 4)).should == true
+    (Rational(-4, 5) == Rational(4, -5)).should == true
+
+    (Rational(bignum_value, 3) == Rational(bignum_value, 3)).should == true
+    (Rational(-bignum_value, 3) == Rational(bignum_value, -3)).should == true
+  end
 end
 
 describe "Rational#== when passed a Float" do
-  it_behaves_like :rational_equal_value_float, :==
+  it "converts self to a Float and compares it with the passed argument" do
+    (Rational(3, 4) == 0.75).should == true
+    (Rational(4, 2) == 2.0).should == true
+    (Rational(-4, 2) == -2.0).should == true
+    (Rational(4, -2) == -2.0).should == true
+  end
 end
 
 describe "Rational#== when passed an Integer" do
-  it_behaves_like :rational_equal_value_int, :==
+  it "returns true if self has the passed argument as numerator and a denominator of 1" do
+    # Rational(x, y) reduces x and y automatically
+    (Rational(4, 2) == 2).should == true
+    (Rational(-4, 2) == -2).should == true
+    (Rational(4, -2) == -2).should == true
+  end
 end
diff --git a/spec/ruby/core/rational/exponent_spec.rb b/spec/ruby/core/rational/exponent_spec.rb
index 622cf22782..88b4a43796 100644
--- a/spec/ruby/core/rational/exponent_spec.rb
+++ b/spec/ruby/core/rational/exponent_spec.rb
@@ -1,5 +1,236 @@
-require_relative '../../shared/rational/exponent'
+require_relative "../../spec_helper"
 
 describe "Rational#**" do
-  it_behaves_like :rational_exponent, :**
+  describe "when passed Rational" do
+    # Guard against the Mathn library
+    guard -> { !defined?(Math.rsqrt) } do
+      it "returns Rational(1) if the exponent is Rational(0)" do
+        (Rational(0) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(1) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(3, 4) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(-1) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(-3, 4) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(bignum_value) ** Rational(0)).should.eql?(Rational(1))
+        (Rational(-bignum_value) ** Rational(0)).should.eql?(Rational(1))
+      end
+
+      it "returns self raised to the argument as a Rational if the exponent's denominator is 1" do
+        (Rational(3, 4) ** Rational(1, 1)).should.eql?(Rational(3, 4))
+        (Rational(3, 4) ** Rational(2, 1)).should.eql?(Rational(9, 16))
+        (Rational(3, 4) ** Rational(-1, 1)).should.eql?(Rational(4, 3))
+        (Rational(3, 4) ** Rational(-2, 1)).should.eql?(Rational(16, 9))
+      end
+
+      it "returns self raised to the argument as a Float if the exponent's denominator is not 1" do
+        (Rational(3, 4) ** Rational(4, 3)).should be_close(0.681420222312052, TOLERANCE)
+        (Rational(3, 4) ** Rational(-4, 3)).should be_close(1.46752322173095, TOLERANCE)
+        (Rational(3, 4) ** Rational(4, -3)).should be_close(1.46752322173095, TOLERANCE)
+      end
+
+      it "returns a complex number when self is negative and the passed argument is not 0" do
+        (Rational(-3, 4) ** Rational(-4, 3)).should be_close(Complex(-0.7337616108654732, 1.2709123906625817), TOLERANCE)
+      end
+    end
+  end
+
+  describe "when passed Integer" do
+    it "returns the Rational value of self raised to the passed argument" do
+      (Rational(3, 4) ** 4).should == Rational(81, 256)
+      (Rational(3, 4) ** -4).should == Rational(256, 81)
+      (Rational(-3, 4) ** -4).should == Rational(256, 81)
+      (Rational(3, -4) ** -4).should == Rational(256, 81)
+
+      (Rational(bignum_value, 4) ** 4).should == Rational(452312848583266388373324160190187140051835877600158453279131187530910662656, 1)
+      (Rational(3, bignum_value) ** -4).should == Rational(115792089237316195423570985008687907853269984665640564039457584007913129639936, 81)
+      (Rational(-bignum_value, 4) ** -4).should == Rational(1, 452312848583266388373324160190187140051835877600158453279131187530910662656)
+      (Rational(3, -bignum_value) ** -4).should == Rational(115792089237316195423570985008687907853269984665640564039457584007913129639936, 81)
+    end
+
+    # Guard against the Mathn library
+    guard -> { !defined?(Math.rsqrt) } do
+      it "returns Rational(1, 1) when the passed argument is 0" do
+        (Rational(3, 4) ** 0).should.eql?(Rational(1, 1))
+        (Rational(-3, 4) ** 0).should.eql?(Rational(1, 1))
+        (Rational(3, -4) ** 0).should.eql?(Rational(1, 1))
+
+        (Rational(bignum_value, 4) ** 0).should.eql?(Rational(1, 1))
+        (Rational(3, -bignum_value) ** 0).should.eql?(Rational(1, 1))
+      end
+    end
+  end
+
+  describe "when passed Bignum" do
+    # #5713
+    it "returns Rational(0) when self is Rational(0) and the exponent is positive" do
+      (Rational(0) ** bignum_value).should.eql?(Rational(0))
+    end
+
+    it "raises ZeroDivisionError when self is Rational(0) and the exponent is negative" do
+      -> { Rational(0) ** -bignum_value }.should.raise(ZeroDivisionError)
+    end
+
+    it "returns Rational(1) when self is Rational(1)" do
+      (Rational(1) **  bignum_value).should.eql?(Rational(1))
+      (Rational(1) ** -bignum_value).should.eql?(Rational(1))
+    end
+
+    it "returns Rational(1) when self is Rational(-1) and the exponent is positive and even" do
+      (Rational(-1) ** bignum_value(0)).should.eql?(Rational(1))
+      (Rational(-1) ** bignum_value(2)).should.eql?(Rational(1))
+    end
+
+    it "returns Rational(-1) when self is Rational(-1) and the exponent is positive and odd" do
+      (Rational(-1) ** bignum_value(1)).should.eql?(Rational(-1))
+      (Rational(-1) ** bignum_value(3)).should.eql?(Rational(-1))
+    end
+
+    ruby_version_is ""..."3.4" do
+      it "returns positive Infinity when self is > 1" do
+        -> {
+          (Rational(2) ** bignum_value).infinite?.should == 1
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+        -> {
+          (Rational(fixnum_max) ** bignum_value).infinite?.should == 1
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+      end
+
+      it "returns 0.0 when self is > 1 and the exponent is negative" do
+        -> {
+          (Rational(2) ** -bignum_value).should.eql?(0.0)
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+        -> {
+          (Rational(fixnum_max) ** -bignum_value).should.eql?(0.0)
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "raises an ArgumentError when self is > 1" do
+        -> {
+          (Rational(2) ** bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+        -> {
+          (Rational(fixnum_max) ** bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+      end
+
+      it "raises an ArgumentError when self is > 1 and the exponent is negative" do
+        -> {
+          (Rational(2) ** -bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+        -> {
+          (Rational(fixnum_max) ** -bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+      end
+
+      it "raises an ArgumentError when self is < -1" do
+        -> {
+          (Rational(-2) ** bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+        -> {
+          (Rational(fixnum_min) ** bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+      end
+
+      it "raises an ArgumentError when self is < -1 and the exponent is negative" do
+        -> {
+          (Rational(-2) ** -bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+        -> {
+          (Rational(fixnum_min) ** -bignum_value)
+        }.should.raise(ArgumentError, "exponent is too large")
+      end
+    end
+
+    # Fails on linux due to pow() bugs in glibc: http://sources.redhat.com/bugzilla/show_bug.cgi?id=3866
+    platform_is_not :linux do
+      ruby_version_is ""..."3.4" do
+        it "returns positive Infinity when self < -1" do
+          -> {
+            (Rational(-2) ** bignum_value).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(-2) ** (bignum_value + 1)).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(fixnum_min) ** bignum_value).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+        end
+
+        it "returns 0.0 when self is < -1 and the exponent is negative" do
+          -> {
+            (Rational(-2) ** -bignum_value).should.eql?(0.0)
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(fixnum_min) ** -bignum_value).should.eql?(0.0)
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+        end
+      end
+    end
+  end
+
+  describe "when passed Float" do
+    it "returns self converted to Float and raised to the passed argument" do
+      (Rational(3, 1) ** 3.0).should.eql?(27.0)
+      (Rational(3, 1) ** 1.5).should be_close(5.19615242270663, TOLERANCE)
+      (Rational(3, 1) ** -1.5).should be_close(0.192450089729875, TOLERANCE)
+    end
+
+    it "returns a complex number if self is negative and the passed argument is not 0" do
+      (Rational(-3, 2) ** 1.5).should be_close(Complex(0.0, -1.8371173070873836), TOLERANCE)
+      (Rational(3, -2) ** 1.5).should be_close(Complex(0.0, -1.8371173070873836), TOLERANCE)
+      (Rational(3, -2) ** -1.5).should be_close(Complex(0.0, 0.5443310539518174), TOLERANCE)
+    end
+
+    it "returns Complex(1.0) when the passed argument is 0.0" do
+      (Rational(3, 4) ** 0.0).should == Complex(1.0)
+      (Rational(-3, 4) ** 0.0).should == Complex(1.0)
+      (Rational(-3, 4) ** 0.0).should == Complex(1.0)
+    end
+  end
+
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj      = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational ** obj
+  end
+
+  it "calls #** on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:**).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational ** obj).should == :result
+  end
+
+  it "raises ZeroDivisionError for Rational(0, 1) passed a negative Integer" do
+    [-1, -4, -9999].each do |exponent|
+      -> { Rational(0, 1) ** exponent }.should.raise(ZeroDivisionError, "divided by 0")
+    end
+  end
+
+  it "raises ZeroDivisionError for Rational(0, 1) passed a negative Rational with denominator 1" do
+    [Rational(-1, 1), Rational(-3, 1)].each do |exponent|
+      -> { Rational(0, 1) ** exponent }.should.raise(ZeroDivisionError, "divided by 0")
+    end
+  end
+
+  # #7513
+  it "raises ZeroDivisionError for Rational(0, 1) passed a negative Rational" do
+    -> { Rational(0, 1) ** Rational(-3, 2) }.should.raise(ZeroDivisionError, "divided by 0")
+  end
+
+  it "returns Infinity for Rational(0, 1) passed a negative Float" do
+    [-1.0, -3.0, -3.14].each do |exponent|
+      (Rational(0, 1) ** exponent).infinite?.should == 1
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/fdiv_spec.rb b/spec/ruby/core/rational/fdiv_spec.rb
index bfb321abaa..118d93dbe7 100644
--- a/spec/ruby/core/rational/fdiv_spec.rb
+++ b/spec/ruby/core/rational/fdiv_spec.rb
@@ -1,5 +1,5 @@
-require_relative '../../shared/rational/fdiv'
+require_relative "../../spec_helper"
 
 describe "Rational#fdiv" do
-  it_behaves_like :rational_fdiv, :fdiv
+  it "needs to be reviewed for spec completeness"
 end
diff --git a/spec/ruby/fixtures/rational.rb b/spec/ruby/core/rational/fixtures/rational.rb
index 844d7f9820..844d7f9820 100644
--- a/spec/ruby/fixtures/rational.rb
+++ b/spec/ruby/core/rational/fixtures/rational.rb
diff --git a/spec/ruby/core/rational/floor_spec.rb b/spec/ruby/core/rational/floor_spec.rb
index 752a2d8815..6d4cee79a9 100644
--- a/spec/ruby/core/rational/floor_spec.rb
+++ b/spec/ruby/core/rational/floor_spec.rb
@@ -1,5 +1,49 @@
-require_relative '../../shared/rational/floor'
+require_relative "../../spec_helper"
+require_relative "../integer/shared/integer_floor_precision"
 
 describe "Rational#floor" do
-  it_behaves_like :rational_floor, :floor
+  context "with values equal to integers" do
+    it_behaves_like :integer_floor_precision, :Rational
+  end
+
+  before do
+    @rational = Rational(2200, 7)
+  end
+
+  describe "with no arguments (precision = 0)" do
+
+    it "returns the Integer value rounded toward negative infinity" do
+      @rational.floor.should.eql? 314
+
+      Rational(1, 2).floor.should.eql? 0
+      Rational(-1, 2).floor.should.eql?(-1)
+      Rational(1, 1).floor.should.eql? 1
+    end
+  end
+
+  describe "with a precision < 0" do
+    it "moves the rounding point n decimal places left, returning an Integer" do
+      @rational.floor(-3).should.eql? 0
+      @rational.floor(-2).should.eql? 300
+      @rational.floor(-1).should.eql? 310
+
+      Rational(100, 2).floor(-1).should.eql? 50
+      Rational(100, 2).floor(-2).should.eql? 0
+      Rational(-100, 2).floor(-1).should.eql?(-50)
+      Rational(-100, 2).floor(-2).should.eql?(-100)
+    end
+  end
+
+  describe "with a precision > 0" do
+    it "moves the rounding point n decimal places right, returning a Rational" do
+      @rational.floor(1).should.eql? Rational(1571, 5)
+      @rational.floor(2).should.eql? Rational(7857, 25)
+      @rational.floor(3).should.eql? Rational(62857, 200)
+
+      Rational(100, 2).floor(1).should.eql? Rational(50, 1)
+      Rational(100, 2).floor(2).should.eql? Rational(50, 1)
+      Rational(-100, 2).floor(1).should.eql? Rational(-50, 1)
+      Rational(-100, 2).floor(2).should.eql? Rational(-50, 1)
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/hash_spec.rb b/spec/ruby/core/rational/hash_spec.rb
index 84cd31518a..528638056a 100644
--- a/spec/ruby/core/rational/hash_spec.rb
+++ b/spec/ruby/core/rational/hash_spec.rb
@@ -1,5 +1,9 @@
-require_relative '../../shared/rational/hash'
+require_relative "../../spec_helper"
 
 describe "Rational#hash" do
-  it_behaves_like :rational_hash, :hash
+  # BUG: Rational(2, 3).hash == Rational(3, 2).hash
+  it "is static" do
+    Rational(2, 3).hash.should == Rational(2, 3).hash
+    Rational(2, 4).hash.should_not == Rational(2, 3).hash
+  end
 end
diff --git a/spec/ruby/core/rational/inspect_spec.rb b/spec/ruby/core/rational/inspect_spec.rb
index ef337ef0ce..edc5cffee9 100644
--- a/spec/ruby/core/rational/inspect_spec.rb
+++ b/spec/ruby/core/rational/inspect_spec.rb
@@ -1,5 +1,14 @@
-require_relative '../../shared/rational/inspect'
+require_relative "../../spec_helper"
 
 describe "Rational#inspect" do
-  it_behaves_like :rational_inspect, :inspect
+  it "returns a string representation of self" do
+    Rational(3, 4).inspect.should == "(3/4)"
+    Rational(-5, 8).inspect.should == "(-5/8)"
+    Rational(-1, -2).inspect.should == "(1/2)"
+
+    # Guard against the Mathn library
+    guard -> { !defined?(Math.rsqrt) } do
+      Rational(bignum_value, 1).inspect.should == "(#{bignum_value}/1)"
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/integer_spec.rb b/spec/ruby/core/rational/integer_spec.rb
index 0f9a3bdead..cd7fa97fcf 100644
--- a/spec/ruby/core/rational/integer_spec.rb
+++ b/spec/ruby/core/rational/integer_spec.rb
@@ -1,12 +1,13 @@
+require_relative "../../spec_helper"
 describe "Rational#integer?" do
   # Guard against the Mathn library
   guard -> { !defined?(Math.rsqrt) } do
     it "returns false for a rational with a numerator and no denominator" do
-      Rational(20).integer?.should be_false
+      Rational(20).integer?.should == false
     end
   end
 
   it "returns false for a rational with a numerator and a denominator" do
-    Rational(20,3).integer?.should be_false
+    Rational(20,3).integer?.should == false
   end
 end
diff --git a/spec/ruby/core/rational/magnitude_spec.rb b/spec/ruby/core/rational/magnitude_spec.rb
index 878fc8f879..f5f667edb1 100644
--- a/spec/ruby/core/rational/magnitude_spec.rb
+++ b/spec/ruby/core/rational/magnitude_spec.rb
@@ -1,4 +1,5 @@
-require_relative '../../shared/rational/abs'
+require_relative "../../spec_helper"
+require_relative 'shared/abs'
 
 describe "Rational#abs" do
   it_behaves_like :rational_abs, :magnitude
diff --git a/spec/ruby/core/rational/marshal_dump_spec.rb b/spec/ruby/core/rational/marshal_dump_spec.rb
index 17a6107cd5..06bf36f166 100644
--- a/spec/ruby/core/rational/marshal_dump_spec.rb
+++ b/spec/ruby/core/rational/marshal_dump_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Rational#marshal_dump" do
   it "is a private method" do
-    Rational.should have_private_instance_method(:marshal_dump, false)
+    Rational.private_instance_methods(false).should.include?(:marshal_dump)
   end
 
   it "dumps numerator and denominator" do
diff --git a/spec/ruby/core/rational/minus_spec.rb b/spec/ruby/core/rational/minus_spec.rb
index 9e0f81556b..4e10e118b9 100644
--- a/spec/ruby/core/rational/minus_spec.rb
+++ b/spec/ruby/core/rational/minus_spec.rb
@@ -1,7 +1,51 @@
-require_relative '../../shared/rational/minus'
-require_relative '../../shared/rational/arithmetic_exception_in_coerce'
+require_relative '../../spec_helper'
+require_relative 'shared/arithmetic_exception_in_coerce'
 
 describe "Rational#-" do
-  it_behaves_like :rational_minus, :-
   it_behaves_like :rational_arithmetic_exception_in_coerce, :-
+
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational - obj
+  end
+
+  it "calls #- on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:-).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational - obj).should == :result
+  end
+end
+
+describe "Rational#- passed a Rational" do
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) - Rational(0, 1)).should.eql?(Rational(3, 4))
+    (Rational(3, 4) - Rational(1, 4)).should.eql?(Rational(1, 2))
+
+    (Rational(3, 4) - Rational(2, 1)).should.eql?(Rational(-5, 4))
+  end
+end
+
+describe "Rational#- passed a Float" do
+  it "returns the result of subtracting other from self as a Float" do
+    (Rational(3, 4) - 0.2).should.eql?(0.55)
+    (Rational(3, 4) - 2.5).should.eql?(-1.75)
+  end
+end
+
+describe "Rational#- passed an Integer" do
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) - 1).should.eql?(Rational(-1, 4))
+    (Rational(3, 4) - 2).should.eql?(Rational(-5, 4))
+  end
 end
diff --git a/spec/ruby/core/rational/modulo_spec.rb b/spec/ruby/core/rational/modulo_spec.rb
index c43f7788e3..6241077f68 100644
--- a/spec/ruby/core/rational/modulo_spec.rb
+++ b/spec/ruby/core/rational/modulo_spec.rb
@@ -1,5 +1,43 @@
-require_relative '../../shared/rational/modulo'
+require_relative "../../spec_helper"
 
 describe "Rational#%" do
-  it_behaves_like :rational_modulo, :%
+  it "returns the remainder when this value is divided by other" do
+    (Rational(2, 3) % Rational(2, 3)).should == Rational(0, 1)
+    (Rational(4, 3) % Rational(2, 3)).should == Rational(0, 1)
+    (Rational(2, -3) % Rational(-2, 3)).should == Rational(0, 1)
+    (Rational(0, -1) % -1).should == Rational(0, 1)
+
+    (Rational(7, 4) % Rational(1, 2)).should == Rational(1, 4)
+    (Rational(7, 4) % 1).should == Rational(3, 4)
+    (Rational(7, 4) % Rational(1, 7)).should == Rational(1, 28)
+
+    (Rational(3, 4) % -1).should == Rational(-1, 4)
+    (Rational(1, -5) % -1).should == Rational(-1, 5)
+  end
+
+  it "returns a Float value when the argument is Float" do
+    (Rational(7, 4) % 1.0).should.is_a?(Float)
+    (Rational(7, 4) % 1.0).should == 0.75
+    (Rational(7, 4) % 0.26).should be_close(0.19, 0.0001)
+  end
+
+  it "raises ZeroDivisionError on zero denominator" do
+    -> {
+      Rational(3, 5) % Rational(0, 1)
+    }.should.raise(ZeroDivisionError)
+
+    -> {
+      Rational(0, 1) % Rational(0, 1)
+    }.should.raise(ZeroDivisionError)
+
+    -> {
+      Rational(3, 5) % 0
+    }.should.raise(ZeroDivisionError)
+  end
+
+  it "raises a ZeroDivisionError when the argument is 0.0" do
+    -> {
+      Rational(3, 5) % 0.0
+    }.should.raise(ZeroDivisionError)
+  end
 end
diff --git a/spec/ruby/core/rational/multiply_spec.rb b/spec/ruby/core/rational/multiply_spec.rb
index ea644074e9..3e059cbc1c 100644
--- a/spec/ruby/core/rational/multiply_spec.rb
+++ b/spec/ruby/core/rational/multiply_spec.rb
@@ -1,19 +1,65 @@
-require_relative '../../shared/rational/multiply'
-require_relative '../../shared/rational/arithmetic_exception_in_coerce'
+require_relative "../../spec_helper"
+require_relative 'shared/arithmetic_exception_in_coerce'
 
 describe "Rational#*" do
-  it_behaves_like :rational_multiply, :*
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational * obj
+  end
+
+  it "calls #* on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:*).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational * obj).should == :result
+  end
+
   it_behaves_like :rational_arithmetic_exception_in_coerce, :*
 end
 
 describe "Rational#* passed a Rational" do
-  it_behaves_like :rational_multiply_rat, :*
+  it "returns self divided by other as a Rational" do
+    (Rational(3, 4) * Rational(3, 4)).should.eql?(Rational(9, 16))
+    (Rational(2, 4) * Rational(1, 4)).should.eql?(Rational(1, 8))
+
+    (Rational(3, 4) * Rational(0, 1)).should.eql?(Rational(0, 4))
+  end
 end
 
 describe "Rational#* passed a Float" do
-  it_behaves_like :rational_multiply_float, :*
+  it "returns self divided by other as a Float" do
+    (Rational(3, 4) * 0.75).should.eql?(0.5625)
+    (Rational(3, 4) * 0.25).should.eql?(0.1875)
+    (Rational(3, 4) * 0.3).should be_close(0.225, TOLERANCE)
+
+    (Rational(-3, 4) * 0.3).should be_close(-0.225, TOLERANCE)
+    (Rational(3, -4) * 0.3).should be_close(-0.225, TOLERANCE)
+    (Rational(3, 4) * -0.3).should be_close(-0.225, TOLERANCE)
+
+    (Rational(3, 4) * 0.0).should.eql?(0.0)
+    (Rational(-3, -4) * 0.0).should.eql?(0.0)
+
+    (Rational(-3, 4) * 0.0).should.eql?(0.0)
+    (Rational(3, -4) * 0.0).should.eql?(0.0)
+  end
 end
 
 describe "Rational#* passed an Integer" do
-  it_behaves_like :rational_multiply_int, :*
+  it "returns self divided by other as a Rational" do
+    (Rational(3, 4) * 2).should.eql?(Rational(3, 2))
+    (Rational(2, 4) * 2).should.eql?(Rational(1, 1))
+    (Rational(6, 7) * -2).should.eql?(Rational(-12, 7))
+
+    (Rational(3, 4) * 0).should.eql?(Rational(0, 4))
+  end
 end
diff --git a/spec/ruby/core/rational/numerator_spec.rb b/spec/ruby/core/rational/numerator_spec.rb
index 85b2ed9e86..631bb4703c 100644
--- a/spec/ruby/core/rational/numerator_spec.rb
+++ b/spec/ruby/core/rational/numerator_spec.rb
@@ -1,5 +1,10 @@
-require_relative '../../shared/rational/numerator'
+require_relative "../../spec_helper"
 
 describe "Rational#numerator" do
-  it_behaves_like :rational_numerator, :numerator
+  it "returns the numerator" do
+    Rational(3, 4).numerator.should.equal?(3)
+    Rational(3, -4).numerator.should.equal?(-3)
+
+    Rational(bignum_value, 1).numerator.should == bignum_value
+  end
 end
diff --git a/spec/ruby/core/rational/plus_spec.rb b/spec/ruby/core/rational/plus_spec.rb
index e7ef3a8f92..92f830a105 100644
--- a/spec/ruby/core/rational/plus_spec.rb
+++ b/spec/ruby/core/rational/plus_spec.rb
@@ -1,18 +1,50 @@
-require_relative '../../shared/rational/plus'
-require_relative '../../shared/rational/arithmetic_exception_in_coerce'
+require_relative "../../spec_helper"
+require_relative 'shared/arithmetic_exception_in_coerce'
 
 describe "Rational#+" do
-  it_behaves_like :rational_plus, :+
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational + obj
+  end
+
+  it "calls #+ on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:+).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    (rational + obj).should == :result
+  end
+
   it_behaves_like :rational_arithmetic_exception_in_coerce, :+
 end
 
 describe "Rational#+ with a Rational" do
-  it_behaves_like :rational_plus_rat, :+
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) + Rational(0, 1)).should.eql?(Rational(3, 4))
+    (Rational(3, 4) + Rational(1, 4)).should.eql?(Rational(1, 1))
+
+    (Rational(3, 4) + Rational(2, 1)).should.eql?(Rational(11, 4))
+  end
 end
 describe "Rational#+ with a Float" do
-  it_behaves_like :rational_plus_float, :+
+  it "returns the result of subtracting other from self as a Float" do
+    (Rational(3, 4) + 0.2).should.eql?(0.95)
+    (Rational(3, 4) + 2.5).should.eql?(3.25)
+  end
 end
 
 describe "Rational#+ with an Integer" do
-  it_behaves_like :rational_plus_int, :+
+  it "returns the result of subtracting other from self as a Rational" do
+    (Rational(3, 4) + 1).should.eql?(Rational(7, 4))
+    (Rational(3, 4) + 2).should.eql?(Rational(11, 4))
+  end
 end
diff --git a/spec/ruby/core/rational/quo_spec.rb b/spec/ruby/core/rational/quo_spec.rb
index 119aca1955..907898ad34 100644
--- a/spec/ruby/core/rational/quo_spec.rb
+++ b/spec/ruby/core/rational/quo_spec.rb
@@ -1,5 +1,25 @@
-require_relative '../../shared/rational/divide'
+require_relative "../../spec_helper"
 
 describe "Rational#quo" do
-  it_behaves_like :rational_divide, :quo
+  it "calls #coerce on the passed argument with self" do
+    rational = Rational(3, 4)
+    obj = mock("Object")
+    obj.should_receive(:coerce).with(rational).and_return([1, 2])
+
+    rational.quo(obj)
+  end
+
+  it "calls #/ on the coerced Rational with the coerced Object" do
+    rational = Rational(3, 4)
+
+    coerced_rational = mock("Coerced Rational")
+    coerced_rational.should_receive(:/).and_return(:result)
+
+    coerced_obj = mock("Coerced Object")
+
+    obj = mock("Object")
+    obj.should_receive(:coerce).and_return([coerced_rational, coerced_obj])
+
+    rational.quo(obj).should == :result
+  end
 end
diff --git a/spec/ruby/core/rational/rational_spec.rb b/spec/ruby/core/rational/rational_spec.rb
index 704e49354e..278c4116a4 100644
--- a/spec/ruby/core/rational/rational_spec.rb
+++ b/spec/ruby/core/rational/rational_spec.rb
@@ -4,4 +4,8 @@ describe "Rational" do
   it "includes Comparable" do
     Rational.include?(Comparable).should == true
   end
+
+  it "does not respond to new" do
+    -> { Rational.new(1) }.should.raise(NoMethodError)
+  end
 end
diff --git a/spec/ruby/core/rational/rationalize_spec.rb b/spec/ruby/core/rational/rationalize_spec.rb
index 3db027d446..9c86824ddd 100644
--- a/spec/ruby/core/rational/rationalize_spec.rb
+++ b/spec/ruby/core/rational/rationalize_spec.rb
@@ -30,7 +30,7 @@ describe "Rational#rationalize" do
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { Rational(1,1).rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { Rational(1,1).rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { Rational(1,1).rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { Rational(1,1).rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/rational/remainder_spec.rb b/spec/ruby/core/rational/remainder_spec.rb
index 0f9442f6f5..86ba4674e6 100644
--- a/spec/ruby/core/rational/remainder_spec.rb
+++ b/spec/ruby/core/rational/remainder_spec.rb
@@ -1,5 +1,5 @@
-require_relative '../../shared/rational/remainder'
+require_relative "../../spec_helper"
 
 describe "Rational#remainder" do
-  it_behaves_like :rational_remainder, :remainder
+  it "needs to be reviewed for spec completeness"
 end
diff --git a/spec/ruby/core/rational/round_spec.rb b/spec/ruby/core/rational/round_spec.rb
index 36614a552d..dd6f66f408 100644
--- a/spec/ruby/core/rational/round_spec.rb
+++ b/spec/ruby/core/rational/round_spec.rb
@@ -1,6 +1,106 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/rational/round'
 
 describe "Rational#round" do
-  it_behaves_like :rational_round, :round
+  before do
+    @rational = Rational(2200, 7)
+  end
+
+  describe "with no arguments (precision = 0)" do
+    it "returns an integer" do
+      @rational.round.should.is_a?(Integer)
+      Rational(0, 1).round(0).should.is_a?(Integer)
+      Rational(124, 1).round(0).should.is_a?(Integer)
+    end
+
+    it "returns the truncated value toward the nearest integer" do
+      @rational.round.should == 314
+      Rational(0, 1).round(0).should == 0
+      Rational(2, 1).round(0).should == 2
+    end
+
+    it "returns the rounded value toward the nearest integer" do
+      Rational(1, 2).round.should == 1
+      Rational(-1, 2).round.should == -1
+      Rational(3, 2).round.should == 2
+      Rational(-3, 2).round.should == -2
+      Rational(5, 2).round.should == 3
+      Rational(-5, 2).round.should == -3
+    end
+  end
+
+  describe "with a precision < 0" do
+    it "returns an integer" do
+      @rational.round(-2).should.is_a?(Integer)
+      @rational.round(-1).should.is_a?(Integer)
+      Rational(0, 1).round(-1).should.is_a?(Integer)
+      Rational(2, 1).round(-1).should.is_a?(Integer)
+    end
+
+    it "moves the truncation point n decimal places left" do
+      @rational.round(-3).should == 0
+      @rational.round(-2).should == 300
+      @rational.round(-1).should == 310
+    end
+  end
+
+  describe "with a precision > 0" do
+    it "returns a Rational" do
+      @rational.round(1).should.is_a?(Rational)
+      @rational.round(2).should.is_a?(Rational)
+      # Guard against the Mathn library
+      guard -> { !defined?(Math.rsqrt) } do
+        Rational(0, 1).round(1).should.is_a?(Rational)
+        Rational(2, 1).round(1).should.is_a?(Rational)
+      end
+    end
+
+    it "moves the truncation point n decimal places right" do
+      @rational.round(1).should == Rational(3143, 10)
+      @rational.round(2).should == Rational(31429, 100)
+      @rational.round(3).should == Rational(157143, 500)
+      Rational(0, 1).round(1).should == Rational(0, 1)
+      Rational(2, 1).round(1).should == Rational(2, 1)
+    end
+
+    it "doesn't alter the value if the precision is too great" do
+      Rational(3, 2).round(10).should == Rational(3, 2).round(20)
+    end
+
+    # #6605
+    it "doesn't fail when rounding to an absurdly large positive precision" do
+      Rational(3, 2).round(2_097_171).should == Rational(3, 2)
+    end
+  end
+
+  describe "with half option" do
+    it "returns an Integer when precision is not passed" do
+      Rational(10, 4).round(half: nil).should == 3
+      Rational(10, 4).round(half: :up).should == 3
+      Rational(10, 4).round(half: :down).should == 2
+      Rational(10, 4).round(half: :even).should == 2
+      Rational(-10, 4).round(half: nil).should == -3
+      Rational(-10, 4).round(half: :up).should == -3
+      Rational(-10, 4).round(half: :down).should == -2
+      Rational(-10, 4).round(half: :even).should == -2
+    end
+
+    it "returns a Rational when the precision is greater than 0" do
+      Rational(25, 100).round(1, half: nil).should == Rational(3, 10)
+      Rational(25, 100).round(1, half: :up).should == Rational(3, 10)
+      Rational(25, 100).round(1, half: :down).should == Rational(1, 5)
+      Rational(25, 100).round(1, half: :even).should == Rational(1, 5)
+      Rational(35, 100).round(1, half: nil).should == Rational(2, 5)
+      Rational(35, 100).round(1, half: :up).should == Rational(2, 5)
+      Rational(35, 100).round(1, half: :down).should == Rational(3, 10)
+      Rational(35, 100).round(1, half: :even).should == Rational(2, 5)
+      Rational(-25, 100).round(1, half: nil).should == Rational(-3, 10)
+      Rational(-25, 100).round(1, half: :up).should == Rational(-3, 10)
+      Rational(-25, 100).round(1, half: :down).should == Rational(-1, 5)
+      Rational(-25, 100).round(1, half: :even).should == Rational(-1, 5)
+    end
+
+    it "raise for a non-existent round mode" do
+      -> { Rational(10, 4).round(half: :nonsense) }.should.raise(ArgumentError, "invalid rounding mode: nonsense")
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/shared/abs.rb b/spec/ruby/core/rational/shared/abs.rb
new file mode 100644
index 0000000000..3d64bcc1a0
--- /dev/null
+++ b/spec/ruby/core/rational/shared/abs.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+
+describe :rational_abs, shared: true do
+  it "returns self's absolute value" do
+    Rational(3, 4).send(@method).should == Rational(3, 4)
+    Rational(-3, 4).send(@method).should == Rational(3, 4)
+    Rational(3, -4).send(@method).should == Rational(3, 4)
+
+    Rational(bignum_value, -bignum_value).send(@method).should == Rational(bignum_value, bignum_value)
+  end
+end
diff --git a/spec/ruby/core/rational/shared/arithmetic_exception_in_coerce.rb b/spec/ruby/core/rational/shared/arithmetic_exception_in_coerce.rb
new file mode 100644
index 0000000000..e15169c912
--- /dev/null
+++ b/spec/ruby/core/rational/shared/arithmetic_exception_in_coerce.rb
@@ -0,0 +1,11 @@
+require_relative '../fixtures/rational'
+
+describe :rational_arithmetic_exception_in_coerce, shared: true do
+  it "does not rescue exception raised in other#coerce" do
+    b = mock("numeric with failed #coerce")
+    b.should_receive(:coerce).and_raise(RationalSpecs::CoerceError)
+
+    # e.g. Rational(3, 4) + b
+    -> { Rational(3, 4).send(@method, b) }.should.raise(RationalSpecs::CoerceError)
+  end
+end
diff --git a/spec/ruby/core/rational/to_f_spec.rb b/spec/ruby/core/rational/to_f_spec.rb
index 15bf1e88dc..40e3f11c0c 100644
--- a/spec/ruby/core/rational/to_f_spec.rb
+++ b/spec/ruby/core/rational/to_f_spec.rb
@@ -1,5 +1,16 @@
-require_relative '../../shared/rational/to_f'
+require_relative "../../spec_helper"
 
 describe "Rational#to_f" do
-  it_behaves_like :rational_to_f, :to_f
+  it "returns self converted to a Float" do
+    Rational(3, 4).to_f.should.eql?(0.75)
+    Rational(3, -4).to_f.should.eql?(-0.75)
+    Rational(-1, 4).to_f.should.eql?(-0.25)
+    Rational(-1, -4).to_f.should.eql?(0.25)
+  end
+
+  it "converts to a Float for large numerator and denominator" do
+    num = 1000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146010000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146010000000000000000000000000000000000048148248609680896326399448564623182963452541226153892315137780403285956264146009
+    den = 2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+    Rational(num, den).to_f.should == 500.0
+  end
 end
diff --git a/spec/ruby/core/rational/to_i_spec.rb b/spec/ruby/core/rational/to_i_spec.rb
index 3deb3664e1..e61b1b6c3b 100644
--- a/spec/ruby/core/rational/to_i_spec.rb
+++ b/spec/ruby/core/rational/to_i_spec.rb
@@ -1,5 +1,12 @@
-require_relative '../../shared/rational/to_i'
+require_relative "../../spec_helper"
 
 describe "Rational#to_i" do
-  it_behaves_like :rational_to_i, :to_i
+  it "converts self to an Integer by truncation" do
+    Rational(7, 4).to_i.should.eql?(1)
+    Rational(11, 4).to_i.should.eql?(2)
+  end
+
+  it "converts self to an Integer by truncation" do
+    Rational(-7, 4).to_i.should.eql?(-1)
+  end
 end
diff --git a/spec/ruby/core/rational/to_r_spec.rb b/spec/ruby/core/rational/to_r_spec.rb
index cc704c965e..eb6097f595 100644
--- a/spec/ruby/core/rational/to_r_spec.rb
+++ b/spec/ruby/core/rational/to_r_spec.rb
@@ -1,11 +1,17 @@
-require_relative '../../shared/rational/to_r'
+require_relative "../../spec_helper"
 
 describe "Rational#to_r" do
-  it_behaves_like :rational_to_r, :to_r
+  it "returns self" do
+    a = Rational(3, 4)
+    a.to_r.should.equal?(a)
+
+    a = Rational(bignum_value, 4)
+    a.to_r.should.equal?(a)
+  end
 
   it "raises TypeError trying to convert BasicObject" do
     obj = BasicObject.new
-    -> { Rational(obj) }.should raise_error(TypeError)
+    -> { Rational(obj) }.should.raise(TypeError)
   end
 
   it "works when a BasicObject has to_r" do
@@ -15,6 +21,6 @@ describe "Rational#to_r" do
 
   it "fails when a BasicObject's to_r does not return a Rational" do
     obj = BasicObject.new; def obj.to_r; 1 end
-    -> { Rational(obj) }.should raise_error(TypeError)
+    -> { Rational(obj) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/rational/to_s_spec.rb b/spec/ruby/core/rational/to_s_spec.rb
index c5c419787c..24e30778e5 100644
--- a/spec/ruby/core/rational/to_s_spec.rb
+++ b/spec/ruby/core/rational/to_s_spec.rb
@@ -1,5 +1,14 @@
-require_relative '../../shared/rational/to_s'
+require_relative "../../spec_helper"
 
 describe "Rational#to_s" do
-  it_behaves_like :rational_to_s, :to_s
+  it "returns a string representation of self" do
+    # Guard against the Mathn library
+    guard -> { !defined?(Math.rsqrt) } do
+      Rational(1, 1).to_s.should == "1/1"
+      Rational(2, 1).to_s.should == "2/1"
+    end
+    Rational(1, 2).to_s.should == "1/2"
+    Rational(-1, 3).to_s.should == "-1/3"
+    Rational(1, -3).to_s.should == "-1/3"
+  end
 end
diff --git a/spec/ruby/core/rational/truncate_spec.rb b/spec/ruby/core/rational/truncate_spec.rb
index 4e72339752..3614431a7f 100644
--- a/spec/ruby/core/rational/truncate_spec.rb
+++ b/spec/ruby/core/rational/truncate_spec.rb
@@ -1,5 +1,71 @@
-require_relative '../../shared/rational/truncate'
+require_relative "../../spec_helper"
 
 describe "Rational#truncate" do
-  it_behaves_like :rational_truncate, :truncate
+  before do
+    @rational = Rational(2200, 7)
+  end
+
+  describe "with no arguments (precision = 0)" do
+    it "returns an integer" do
+      @rational.truncate.should.is_a?(Integer)
+    end
+
+    it "returns the truncated value toward 0" do
+      @rational.truncate.should == 314
+      Rational(1, 2).truncate.should == 0
+      Rational(-1, 2).truncate.should == 0
+    end
+  end
+
+  describe "with an explicit precision = 0" do
+    it "returns an integer" do
+      @rational.truncate(0).should.is_a?(Integer)
+    end
+
+    it "returns the truncated value toward 0" do
+      @rational.truncate(0).should == 314
+      Rational(1, 2).truncate(0).should == 0
+      Rational(-1, 2).truncate(0).should == 0
+    end
+  end
+
+  describe "with a precision < 0" do
+    it "returns an integer" do
+      @rational.truncate(-2).should.is_a?(Integer)
+      @rational.truncate(-1).should.is_a?(Integer)
+    end
+
+    it "moves the truncation point n decimal places left" do
+      @rational.truncate(-3).should == 0
+      @rational.truncate(-2).should == 300
+      @rational.truncate(-1).should == 310
+    end
+  end
+
+  describe "with a precision > 0" do
+    it "returns a Rational" do
+      @rational.truncate(1).should.is_a?(Rational)
+      @rational.truncate(2).should.is_a?(Rational)
+    end
+
+    it "moves the truncation point n decimal places right" do
+      @rational.truncate(1).should == Rational(1571, 5)
+      @rational.truncate(2).should == Rational(7857, 25)
+      @rational.truncate(3).should == Rational(62857, 200)
+    end
+  end
+
+  describe "with an invalid value for precision" do
+    it "raises a TypeError" do
+      -> { @rational.truncate(nil) }.should.raise(TypeError, "not an integer")
+      -> { @rational.truncate(1.0) }.should.raise(TypeError, "not an integer")
+      -> { @rational.truncate('') }.should.raise(TypeError, "not an integer")
+    end
+
+    it "does not call to_int on the argument" do
+      object = Object.new
+      object.should_not_receive(:to_int)
+      -> { @rational.truncate(object) }.should.raise(TypeError, "not an integer")
+    end
+  end
 end
diff --git a/spec/ruby/core/rational/zero_spec.rb b/spec/ruby/core/rational/zero_spec.rb
index e6dd751922..2e4f783d5c 100644
--- a/spec/ruby/core/rational/zero_spec.rb
+++ b/spec/ruby/core/rational/zero_spec.rb
@@ -1,13 +1,14 @@
+require_relative "../../spec_helper"
 describe "Rational#zero?" do
   it "returns true if the numerator is 0" do
-    Rational(0,26).zero?.should be_true
+    Rational(0,26).zero?.should == true
   end
 
   it "returns true if the numerator is 0.0" do
-    Rational(0.0,26).zero?.should be_true
+    Rational(0.0,26).zero?.should == true
   end
 
   it "returns false if the numerator isn't 0" do
-    Rational(26).zero?.should be_false
+    Rational(26).zero?.should == false
   end
 end
diff --git a/spec/ruby/core/refinement/append_features_spec.rb b/spec/ruby/core/refinement/append_features_spec.rb
new file mode 100644
index 0000000000..cffc9ed308
--- /dev/null
+++ b/spec/ruby/core/refinement/append_features_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+
+describe "Refinement#append_features" do
+  it "is not defined" do
+    Refinement.private_instance_methods(true).should_not.include?(:append_features)
+  end
+
+  it "is not called by Module#include" do
+    c = Class.new
+    Module.new do
+      refine c do
+        called = false
+        define_method(:append_features){called = true}
+        proc{c.include(self)}.should.raise(TypeError)
+        called.should == false
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/extend_object_spec.rb b/spec/ruby/core/refinement/extend_object_spec.rb
new file mode 100644
index 0000000000..f6fe2a60ea
--- /dev/null
+++ b/spec/ruby/core/refinement/extend_object_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../spec_helper'
+
+describe "Refinement#extend_object" do
+  it "is not defined" do
+    Refinement.private_instance_methods(true).should_not.include?(:extend_object)
+  end
+
+  it "is not called by Object#extend" do
+    c = Class.new
+    Module.new do
+      refine c do
+        called = false
+        define_method(:extend_object) { called = true }
+        -> {
+          c.extend(self)
+        }.should.raise(TypeError)
+        called.should == false
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/fixtures/classes.rb b/spec/ruby/core/refinement/fixtures/classes.rb
new file mode 100644
index 0000000000..94324db47c
--- /dev/null
+++ b/spec/ruby/core/refinement/fixtures/classes.rb
@@ -0,0 +1,10 @@
+module RefinementSpec
+
+  module ModuleWithAncestors
+    include Module.new do
+      def indent(level)
+        " " * level + self
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/import_methods_spec.rb b/spec/ruby/core/refinement/import_methods_spec.rb
new file mode 100644
index 0000000000..bcb5e9b066
--- /dev/null
+++ b/spec/ruby/core/refinement/import_methods_spec.rb
@@ -0,0 +1,287 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Refinement#import_methods" do
+  context "when methods are defined in Ruby code" do
+    it "imports methods" do
+      str_utils = Module.new do
+        def indent(level)
+          " " * level + self
+        end
+      end
+
+      Module.new do
+        refine String do
+          import_methods str_utils
+          "foo".indent(3).should == "   foo"
+        end
+      end
+    end
+
+    it "throws an exception when argument is not a module" do
+      Module.new do
+        refine String do
+          -> {
+            import_methods Integer
+          }.should.raise(TypeError, "wrong argument type Class (expected Module)")
+        end
+      end
+    end
+
+    it "imports methods from multiple modules" do
+      str_utils = Module.new do
+        def indent(level)
+          " " * level + self
+        end
+      end
+
+      str_utils_fancy = Module.new do
+        def indent_star(level)
+          "*" * level + self
+        end
+      end
+
+      Module.new do
+        refine String do
+          import_methods str_utils, str_utils_fancy
+          "foo".indent(3).should == "   foo"
+          "foo".indent_star(3).should == "***foo"
+        end
+      end
+    end
+
+    it "imports a method defined in the last module if method with same name is defined in multiple modules" do
+      str_utils = Module.new do
+        def indent(level)
+          " " * level + self
+        end
+      end
+
+      str_utils_fancy = Module.new do
+        def indent(level)
+          "*" * level + self
+        end
+      end
+
+      Module.new do
+        refine String do
+          import_methods str_utils, str_utils_fancy
+          "foo".indent(3).should == "***foo"
+        end
+      end
+    end
+
+    it "still imports methods of modules listed before a module that contains method not defined in Ruby" do
+      str_utils = Module.new do
+        def indent(level)
+          " " * level + self
+        end
+      end
+
+      string_refined = Module.new do
+        refine String do
+          -> {
+            import_methods str_utils, Kernel
+          }.should.raise(ArgumentError)
+        end
+      end
+
+      Module.new do
+        using string_refined
+        "foo".indent(3).should == "   foo"
+      end
+    end
+  end
+
+  it "warns if a module includes/prepends some other module" do
+    module1 = Module.new do
+    end
+
+    module2 = Module.new do
+      include module1
+    end
+
+    Module.new do
+      refine String do
+        -> {
+          import_methods module2
+        }.should complain(/warning: #<Module:\w*> has ancestors, but Refinement#import_methods doesn't import their methods/)
+      end
+    end
+
+    Module.new do
+      refine String do
+        -> {
+          import_methods RefinementSpec::ModuleWithAncestors
+        }.should complain(/warning: RefinementSpec::ModuleWithAncestors has ancestors, but Refinement#import_methods doesn't import their methods/)
+      end
+    end
+  end
+
+  it "doesn't import methods from included/prepended modules" do
+    Module.new do
+      refine String do
+        suppress_warning { import_methods RefinementSpec::ModuleWithAncestors }
+      end
+
+      using self
+      -> {
+        "foo".indent(3)
+      }.should.raise(NoMethodError, /undefined method [`']indent' for ("foo":String|an instance of String)/)
+    end
+  end
+
+  it "doesn't import any methods if one of the arguments is not a module" do
+    str_utils = Module.new do
+      def indent(level)
+        " " * level + self
+      end
+    end
+
+    string_refined = Module.new do
+      refine String do
+        -> {
+          import_methods str_utils, Integer
+        }.should.raise(TypeError)
+      end
+    end
+
+    Module.new do
+      using string_refined
+      -> {
+        "foo".indent(3)
+      }.should.raise(NoMethodError)
+    end
+  end
+
+  it "imports methods from multiple modules so that methods see other's module's methods" do
+    str_utils = Module.new do
+      def indent(level)
+        " " * level + self
+      end
+    end
+
+    str_utils_normal = Module.new do
+      def indent_normal(level)
+        self.indent(level)
+      end
+    end
+
+    Module.new do
+      refine String do
+        import_methods str_utils, str_utils_normal
+      end
+
+      using self
+      "foo".indent_normal(3).should == "   foo"
+    end
+  end
+
+  it "imports methods from module so that methods can see each other" do
+    str_utils = Module.new do
+      def indent(level)
+        " " * level + self
+      end
+
+      def indent_with_dot(level)
+        self.indent(level) + "."
+      end
+    end
+
+    Module.new do
+      refine String do
+        import_methods str_utils
+      end
+
+      using self
+      "foo".indent_with_dot(3).should == "   foo."
+    end
+  end
+
+  it "doesn't import module's class methods" do
+    str_utils = Module.new do
+      def self.indent(level)
+        " " * level + self
+      end
+    end
+
+    Module.new do
+      refine String do
+        import_methods str_utils
+      end
+
+      using self
+      -> {
+        String.indent(3)
+      }.should.raise(NoMethodError, /undefined method [`']indent' for (String:Class|class String)/)
+    end
+  end
+
+  it "imports module methods with super" do
+    class_to_refine = Class.new do
+      def foo(number)
+        2 * number
+      end
+    end
+
+    extension = Module.new do
+      def foo(number)
+        super * 2
+      end
+    end
+
+    refinement = Module.new do
+      refine class_to_refine do
+        import_methods extension
+      end
+    end
+
+    Module.new do
+      using refinement
+      class_to_refine.new.foo(2).should == 8
+    end
+  end
+
+  it "correctly sets owner as the refinement module" do
+    str_utils = Module.new do
+      def indent(level)
+        " " * level + self
+      end
+    end
+
+    refinement = Module.new do
+      refine String do
+        import_methods str_utils
+      end
+    end
+
+    Module.new do
+      using refinement
+
+      String.instance_method(:indent).owner.should == refinement.refinements.first
+    end
+  end
+
+  context "when methods are not defined in Ruby code" do
+    it "raises ArgumentError" do
+      Module.new do
+        refine String do
+          -> {
+            import_methods Kernel
+          }.should.raise(ArgumentError)
+        end
+      end
+    end
+
+    it "raises ArgumentError when importing methods from C extension" do
+      require 'zlib'
+      Module.new do
+        refine String do
+          -> {
+            import_methods Zlib
+          }.should.raise(ArgumentError, /Can't import method which is not defined with Ruby code: Zlib#*/)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/include_spec.rb b/spec/ruby/core/refinement/include_spec.rb
new file mode 100644
index 0000000000..55ac89ffb5
--- /dev/null
+++ b/spec/ruby/core/refinement/include_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "Refinement#include" do
+  it "raises a TypeError" do
+    Module.new do
+      refine String do
+        -> {
+          include Module.new
+        }.should.raise(TypeError, "Refinement#include has been removed")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/prepend_features_spec.rb b/spec/ruby/core/refinement/prepend_features_spec.rb
new file mode 100644
index 0000000000..9dc5838f1f
--- /dev/null
+++ b/spec/ruby/core/refinement/prepend_features_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+
+describe "Refinement#prepend_features" do
+  it "is not defined" do
+    Refinement.private_instance_methods(true).should_not.include?(:prepend_features)
+  end
+
+  it "is not called by Module#prepend" do
+    c = Class.new
+    Module.new do
+      refine c do
+        called = false
+        define_method(:prepend_features){called = true}
+        proc{c.prepend(self)}.should.raise(TypeError)
+        called.should == false
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/prepend_spec.rb b/spec/ruby/core/refinement/prepend_spec.rb
new file mode 100644
index 0000000000..fd70dd6f97
--- /dev/null
+++ b/spec/ruby/core/refinement/prepend_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "Refinement#prepend" do
+  it "raises a TypeError" do
+    Module.new do
+      refine String do
+        -> {
+          prepend Module.new
+        }.should.raise(TypeError, "Refinement#prepend has been removed")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/refined_class_spec.rb b/spec/ruby/core/refinement/refined_class_spec.rb
new file mode 100644
index 0000000000..b532d9a773
--- /dev/null
+++ b/spec/ruby/core/refinement/refined_class_spec.rb
@@ -0,0 +1,34 @@
+require_relative "../../spec_helper"
+require_relative 'shared/target'
+
+describe "Refinement#refined_class" do
+  ruby_version_is ""..."3.4" do
+    it "has been deprecated in favour of Refinement#target" do
+      refinement_int = nil
+
+      Module.new do
+        refine Integer do
+          refinement_int = self
+        end
+      end
+
+      -> {
+        refinement_int.refined_class
+      }.should complain(/warning: Refinement#refined_class is deprecated and will be removed in Ruby 3.4; use Refinement#target instead/)
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "has been removed" do
+      refinement_int = nil
+
+      Module.new do
+        refine Integer do
+          refinement_int = self
+        end
+      end
+
+      refinement_int.should_not.respond_to?(:refined_class)
+    end
+  end
+end
diff --git a/spec/ruby/core/refinement/shared/target.rb b/spec/ruby/core/refinement/shared/target.rb
new file mode 100644
index 0000000000..79557bea0b
--- /dev/null
+++ b/spec/ruby/core/refinement/shared/target.rb
@@ -0,0 +1,13 @@
+describe :refinement_target, shared: true do
+  it "returns the class refined by the receiver" do
+    refinement_int = nil
+
+    Module.new do
+      refine Integer do
+        refinement_int = self
+      end
+    end
+
+    refinement_int.send(@method).should == Integer
+  end
+end
diff --git a/spec/ruby/core/refinement/target_spec.rb b/spec/ruby/core/refinement/target_spec.rb
new file mode 100644
index 0000000000..8bd816aea6
--- /dev/null
+++ b/spec/ruby/core/refinement/target_spec.rb
@@ -0,0 +1,6 @@
+require_relative "../../spec_helper"
+require_relative 'shared/target'
+
+describe "Refinement#target" do
+  it_behaves_like :refinement_target, :target
+end
diff --git a/spec/ruby/core/regexp/case_compare_spec.rb b/spec/ruby/core/regexp/case_compare_spec.rb
index a621713f6f..29aada70bc 100644
--- a/spec/ruby/core/regexp/case_compare_spec.rb
+++ b/spec/ruby/core/regexp/case_compare_spec.rb
@@ -2,24 +2,34 @@ require_relative '../../spec_helper'
 
 describe "Regexp#===" do
   it "is true if there is a match" do
-    (/abc/ === "aabcc").should be_true
+    (/abc/ === "aabcc").should == true
   end
 
   it "is false if there is no match" do
-    (/abc/ === "xyz").should be_false
+    (/abc/ === "xyz").should == false
   end
 
   it "returns true if it matches a Symbol" do
-    (/a/ === :a).should be_true
+    (/a/ === :a).should == true
   end
 
   it "returns false if it does not match a Symbol" do
-    (/a/ === :b).should be_false
+    (/a/ === :b).should == false
   end
 
   # mirroring https://github.com/ruby/ruby/blob/master/test/ruby/test_regexp.rb
   it "returns false if the other value cannot be coerced to a string" do
-    (/abc/ === nil).should be_false
-    (/abc/ === /abc/).should be_false
+    (/abc/ === nil).should == false
+    (/abc/ === /abc/).should == false
+  end
+
+  it "uses #to_str on string-like objects" do
+    stringlike = Class.new do
+      def to_str
+        "abc"
+      end
+    end.new
+
+    (/abc/ === stringlike).should == true
   end
 end
diff --git a/spec/ruby/core/regexp/casefold_spec.rb b/spec/ruby/core/regexp/casefold_spec.rb
index d84a2d63c9..d36467a989 100644
--- a/spec/ruby/core/regexp/casefold_spec.rb
+++ b/spec/ruby/core/regexp/casefold_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Regexp#casefold?" do
   it "returns the value of the case-insensitive flag" do
-    /abc/i.casefold?.should == true
-    /xyz/.casefold?.should == false
+    /abc/i.should.casefold?
+    /xyz/.should_not.casefold?
   end
 end
diff --git a/spec/ruby/core/regexp/compile_spec.rb b/spec/ruby/core/regexp/compile_spec.rb
index 329cb4f753..887c8d77dc 100644
--- a/spec/ruby/core/regexp/compile_spec.rb
+++ b/spec/ruby/core/regexp/compile_spec.rb
@@ -13,3 +13,7 @@ end
 describe "Regexp.compile given a Regexp" do
   it_behaves_like :regexp_new_regexp, :compile
 end
+
+describe "Regexp.compile given a non-String/Regexp" do
+  it_behaves_like :regexp_new_non_string_or_regexp, :compile
+end
diff --git a/spec/ruby/core/regexp/encoding_spec.rb b/spec/ruby/core/regexp/encoding_spec.rb
index 6ce6f8b3ca..fb4fdba064 100644
--- a/spec/ruby/core/regexp/encoding_spec.rb
+++ b/spec/ruby/core/regexp/encoding_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "Regexp#encoding" do
   it "returns an Encoding object" do
-    /glar/.encoding.should be_an_instance_of(Encoding)
+    /glar/.encoding.should.instance_of?(Encoding)
   end
 
   it "defaults to US-ASCII if the Regexp contains only US-ASCII character" do
@@ -55,4 +55,8 @@ describe "Regexp#encoding" do
     /foo/.encoding.should_not == Encoding::EUC_JP
     Encoding.default_internal = old_internal
   end
+
+  it "allows otherwise invalid characters if NOENCODING is specified" do
+    Regexp.new('([\x00-\xFF])', Regexp::IGNORECASE | Regexp::NOENCODING).encoding.should == Encoding::BINARY
+  end
 end
diff --git a/spec/ruby/core/regexp/fixed_encoding_spec.rb b/spec/ruby/core/regexp/fixed_encoding_spec.rb
index 29d0a22c53..5d8b1c2860 100644
--- a/spec/ruby/core/regexp/fixed_encoding_spec.rb
+++ b/spec/ruby/core/regexp/fixed_encoding_spec.rb
@@ -3,34 +3,34 @@ require_relative '../../spec_helper'
 
 describe "Regexp#fixed_encoding?" do
   it "returns false by default" do
-    /needle/.fixed_encoding?.should be_false
+    /needle/.fixed_encoding?.should == false
   end
 
   it "returns false if the 'n' modifier was supplied to the Regexp" do
-    /needle/n.fixed_encoding?.should be_false
+    /needle/n.fixed_encoding?.should == false
   end
 
   it "returns true if the 'u' modifier was supplied to the Regexp" do
-    /needle/u.fixed_encoding?.should be_true
+    /needle/u.fixed_encoding?.should == true
   end
 
   it "returns true if the 's' modifier was supplied to the Regexp" do
-    /needle/s.fixed_encoding?.should be_true
+    /needle/s.fixed_encoding?.should == true
   end
 
   it "returns true if the 'e' modifier was supplied to the Regexp" do
-    /needle/e.fixed_encoding?.should be_true
+    /needle/e.fixed_encoding?.should == true
   end
 
   it "returns true if the Regexp contains a \\u escape" do
-    /needle \u{8768}/.fixed_encoding?.should be_true
+    /needle \u{8768}/.fixed_encoding?.should == true
   end
 
   it "returns true if the Regexp contains a UTF-8 literal" do
-    /文字化け/.fixed_encoding?.should be_true
+    /文字化け/.fixed_encoding?.should == true
   end
 
   it "returns true if the Regexp was created with the Regexp::FIXEDENCODING option" do
-    Regexp.new("", Regexp::FIXEDENCODING).fixed_encoding?.should be_true
+    Regexp.new("", Regexp::FIXEDENCODING).fixed_encoding?.should == true
   end
 end
diff --git a/spec/ruby/core/regexp/initialize_spec.rb b/spec/ruby/core/regexp/initialize_spec.rb
index 36fd5c7bf2..1c0133acae 100644
--- a/spec/ruby/core/regexp/initialize_spec.rb
+++ b/spec/ruby/core/regexp/initialize_spec.rb
@@ -2,14 +2,28 @@ require_relative '../../spec_helper'
 
 describe "Regexp#initialize" do
   it "is a private method" do
-    Regexp.should have_private_method(:initialize)
+    Regexp.private_instance_methods(false).should.include?(:initialize)
   end
 
-  it "raises a SecurityError on a Regexp literal" do
-    -> { //.send(:initialize, "") }.should raise_error(SecurityError)
+  it "raises a FrozenError on a Regexp literal" do
+    -> { //.send(:initialize, "") }.should.raise(FrozenError)
   end
 
-  it "raises a TypeError on an initialized non-literal Regexp" do
-    -> { Regexp.new("").send(:initialize, "") }.should raise_error(TypeError)
+  ruby_version_is "4.1" do
+    it "raises a FrozenError on an initialized non-literal Regexp" do
+      regexp = Regexp.new("")
+      -> { regexp.send(:initialize, "") }.should.raise(FrozenError)
+    end
+  end
+
+  ruby_version_is ""..."4.1" do
+    it "raises a TypeError on an initialized non-literal Regexp" do
+      -> { Regexp.new("").send(:initialize, "") }.should.raise(TypeError)
+    end
+  end
+
+  it "raises a TypeError on an initialized non-literal Regexp subclass" do
+    r = Class.new(Regexp).new("")
+    -> { r.send(:initialize, "") }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/regexp/last_match_spec.rb b/spec/ruby/core/regexp/last_match_spec.rb
index ed496b7941..6c256cc1cf 100644
--- a/spec/ruby/core/regexp/last_match_spec.rb
+++ b/spec/ruby/core/regexp/last_match_spec.rb
@@ -4,11 +4,53 @@ describe "Regexp.last_match" do
   it "returns MatchData instance when not passed arguments" do
     /c(.)t/ =~ 'cat'
 
-    Regexp.last_match.should be_kind_of(MatchData)
+    Regexp.last_match.should.is_a?(MatchData)
   end
 
-  it "returns the nth field in this MatchData when passed a Fixnum" do
+  it "returns the nth field in this MatchData when passed an Integer" do
     /c(.)t/ =~ 'cat'
     Regexp.last_match(1).should == 'a'
   end
+
+  it "returns nil when there is no match" do
+    /foo/ =~ "TEST123"
+    Regexp.last_match(:test).should == nil
+    Regexp.last_match(1).should == nil
+    Regexp.last_match(Object.new).should == nil
+    Regexp.last_match("test").should == nil
+  end
+
+  describe "when given a Symbol" do
+    it "returns a named capture" do
+      /(?<test>[A-Z]+.*)/ =~ "TEST123"
+      Regexp.last_match(:test).should == "TEST123"
+    end
+
+    it "raises an IndexError when given a missing name" do
+      /(?<test>[A-Z]+.*)/ =~ "TEST123"
+      -> { Regexp.last_match(:missing) }.should.raise(IndexError)
+    end
+  end
+
+  describe "when given a String" do
+    it "returns a named capture" do
+      /(?<test>[A-Z]+.*)/ =~ "TEST123"
+      Regexp.last_match("test").should == "TEST123"
+    end
+  end
+
+  describe "when given an Object" do
+    it "coerces argument to an index using #to_int" do
+      obj = mock("converted to int")
+      obj.should_receive(:to_int).and_return(1)
+      /(?<test>[A-Z]+.*)/ =~ "TEST123"
+      Regexp.last_match(obj).should == "TEST123"
+    end
+
+    it "raises a TypeError when unable to coerce" do
+      obj = Object.new
+      /(?<test>[A-Z]+.*)/ =~ "TEST123"
+      -> { Regexp.last_match(obj) }.should.raise(TypeError)
+    end
+  end
 end
diff --git a/spec/ruby/core/regexp/linear_time_spec.rb b/spec/ruby/core/regexp/linear_time_spec.rb
new file mode 100644
index 0000000000..f70021dfed
--- /dev/null
+++ b/spec/ruby/core/regexp/linear_time_spec.rb
@@ -0,0 +1,80 @@
+require_relative '../../spec_helper'
+
+describe "Regexp.linear_time?" do
+  it "returns true if matching can be done in linear time" do
+    Regexp.linear_time?(/a/).should == true
+    Regexp.linear_time?('a').should == true
+  end
+
+  it "returns true if matching can be done in linear time for a binary Regexp" do
+    Regexp.linear_time?(/[\x80-\xff]/n).should == true
+  end
+
+  it "return false if matching can't be done in linear time" do
+    Regexp.linear_time?(/(a)\1/).should == false
+    Regexp.linear_time?("(a)\\1").should == false
+  end
+
+  it "accepts flags for string argument" do
+    Regexp.linear_time?('a', Regexp::IGNORECASE).should == true
+  end
+
+  it "warns about flags being ignored for regexp arguments" do
+    -> {
+      Regexp.linear_time?(/a/, Regexp::IGNORECASE)
+    }.should complain(/warning: flags ignored/)
+  end
+
+  it "returns true for positive lookahead" do
+    Regexp.linear_time?(/a*(?:(?=a*)a)*b/).should == true
+  end
+
+  it "returns true for positive lookbehind" do
+    Regexp.linear_time?(/a*(?:(?<=a)a*)*b/).should == true
+  end
+
+  it "returns true for negative lookbehind" do
+    Regexp.linear_time?(/a*(?:(?<!a)a*)*b/).should == true
+  end
+
+  # There are two known ways to make Regexp linear:
+  # * Using a DFA (deterministic finite-state automaton) Regexp engine, which always matches in linear time (e.g. TruffleRuby with TRegex)
+  # * Caching position and state to avoid catastrophic backtracking (e.g. CRuby: https://bugs.ruby-lang.org/issues/19104)
+  #
+  # Both approach should be allowed and given that DFA Regexp engines
+  # are much faster there should be no specs preventing using them.
+  uses_regexp_caching = RUBY_ENGINE == 'ruby'
+  uses_dfa_regexp_engine = !uses_regexp_caching
+
+  # The following specs should not be relied upon,
+  # they are here only to illustrate differences between Regexp engines.
+  guard -> { uses_regexp_caching } do
+    it "returns true for negative lookahead" do
+      Regexp.linear_time?(/a*(?:(?!a*)a*)*b/).should == true
+    end
+
+    it "returns true for atomic groups" do
+      Regexp.linear_time?(/a*(?:(?>a)a*)*b/).should == true
+    end
+
+    it "returns true for possessive quantifiers" do
+      Regexp.linear_time?(/a*(?:(?:a)?+a*)*b/).should == true
+    end
+
+    it "returns true for positive lookbehind with capture group" do
+      Regexp.linear_time?(/.(?<=(a))/).should == true
+    end
+  end
+
+  # The following specs should not be relied upon,
+  # they are here only to illustrate differences between Regexp engines.
+  guard -> { uses_dfa_regexp_engine } do
+    it "returns true for non-recursive subexpression call" do
+      Regexp.linear_time?(/(?<a>a){0}\g<a>/).should == true
+    end
+
+    it "returns true for positive lookahead with capture group" do
+      Regexp.linear_time?(/x+(?=(a))/).should == true
+    end
+  end
+end
diff --git a/spec/ruby/core/regexp/match_spec.rb b/spec/ruby/core/regexp/match_spec.rb
index a68448b39c..276cecc8e4 100644
--- a/spec/ruby/core/regexp/match_spec.rb
+++ b/spec/ruby/core/regexp/match_spec.rb
@@ -3,11 +3,11 @@ require_relative '../../spec_helper'
 
 describe :regexp_match, shared: true do
   it "returns nil if there is no match" do
-    /xyz/.send(@method,"abxyc").should be_nil
+    /xyz/.send(@method,"abxyc").should == nil
   end
 
   it "returns nil if the object is nil" do
-    /\w+/.send(@method, nil).should be_nil
+    /\w+/.send(@method, nil).should == nil
   end
 end
 
@@ -27,15 +27,19 @@ describe "Regexp#match" do
   it_behaves_like :regexp_match, :match
 
   it "returns a MatchData object" do
-    /(.)(.)(.)/.match("abc").should be_kind_of(MatchData)
+    /(.)(.)(.)/.match("abc").should.is_a?(MatchData)
   end
 
   it "returns a MatchData object, when argument is a Symbol" do
-    /(.)(.)(.)/.match(:abc).should be_kind_of(MatchData)
+    /(.)(.)(.)/.match(:abc).should.is_a?(MatchData)
   end
 
   it "raises a TypeError on an uninitialized Regexp" do
-    -> { Regexp.allocate.match('foo') }.should raise_error(TypeError)
+    -> { Regexp.allocate.match('foo') }.should.raise(TypeError)
+  end
+
+  it "raises TypeError on an uninitialized Regexp" do
+    -> { Regexp.allocate.match('foo'.encode("UTF-16LE")) }.should.raise(TypeError)
   end
 
   describe "with [string, position]" do
@@ -50,7 +54,7 @@ describe "Regexp#match" do
 
       it "raises an ArgumentError for an invalid encoding" do
         x96 = ([150].pack('C')).force_encoding('utf-8')
-        -> { /(.).(.)/.match("Hello, #{x96} world!", 1) }.should raise_error(ArgumentError)
+        -> { /(.).(.)/.match("Hello, #{x96} world!", 1) }.should.raise(ArgumentError)
       end
     end
 
@@ -65,14 +69,14 @@ describe "Regexp#match" do
 
       it "raises an ArgumentError for an invalid encoding" do
         x96 = ([150].pack('C')).force_encoding('utf-8')
-        -> { /(.).(.)/.match("Hello, #{x96} world!", -1) }.should raise_error(ArgumentError)
+        -> { /(.).(.)/.match("Hello, #{x96} world!", -1) }.should.raise(ArgumentError)
       end
     end
 
     describe "when passed a block" do
       it "yields the MatchData" do
         /./.match("abc") {|m| ScratchPad.record m }
-        ScratchPad.recorded.should be_kind_of(MatchData)
+        ScratchPad.recorded.should.is_a?(MatchData)
       end
 
       it "returns the block result" do
@@ -90,20 +94,20 @@ describe "Regexp#match" do
   it "resets $~ if passed nil" do
     # set $~
     /./.match("a")
-    $~.should be_kind_of(MatchData)
+    $~.should.is_a?(MatchData)
 
     /1/.match(nil)
-    $~.should be_nil
+    $~.should == nil
   end
 
   it "raises TypeError when the given argument cannot be coerced to String" do
     f = 1
-    -> { /foo/.match(f)[0] }.should raise_error(TypeError)
+    -> { /foo/.match(f)[0] }.should.raise(TypeError)
   end
 
   it "raises TypeError when the given argument is an Exception" do
     f = Exception.new("foo")
-    -> { /foo/.match(f)[0] }.should raise_error(TypeError)
+    -> { /foo/.match(f)[0] }.should.raise(TypeError)
   end
 end
 
@@ -115,22 +119,22 @@ describe "Regexp#match?" do
 
   context "when matches the given value" do
     it "returns true but does not set Regexp.last_match" do
-      /string/i.match?('string').should be_true
-      Regexp.last_match.should be_nil
+      /string/i.match?('string').should == true
+      Regexp.last_match.should == nil
     end
   end
 
   it "returns false when does not match the given value" do
-    /STRING/.match?('string').should be_false
+    /STRING/.match?('string').should == false
   end
 
   it "takes matching position as the 2nd argument" do
-    /str/i.match?('string', 0).should be_true
-    /str/i.match?('string', 1).should be_false
+    /str/i.match?('string', 0).should == true
+    /str/i.match?('string', 1).should == false
   end
 
   it "returns false when given nil" do
-    /./.match?(nil).should be_false
+    /./.match?(nil).should == false
   end
 end
 
diff --git a/spec/ruby/core/regexp/named_captures_spec.rb b/spec/ruby/core/regexp/named_captures_spec.rb
index 1a68d7877b..4d3fdd23ab 100644
--- a/spec/ruby/core/regexp/named_captures_spec.rb
+++ b/spec/ruby/core/regexp/named_captures_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Regexp#named_captures" do
   it "returns a Hash" do
-    /foo/.named_captures.should be_an_instance_of(Hash)
+    /foo/.named_captures.should.instance_of?(Hash)
   end
 
   it "returns an empty Hash when there are no capture groups" do
@@ -17,7 +17,7 @@ describe "Regexp#named_captures" do
   it "sets the values of the Hash to Arrays" do
     rex = /this (?<is>is) [aA] (?<pat>pate?rn)/
     rex.named_captures.values.each do |value|
-      value.should be_an_instance_of(Array)
+      value.should.instance_of?(Array)
     end
   end
 
diff --git a/spec/ruby/core/regexp/names_spec.rb b/spec/ruby/core/regexp/names_spec.rb
index 099768fd26..9013f41e20 100644
--- a/spec/ruby/core/regexp/names_spec.rb
+++ b/spec/ruby/core/regexp/names_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Regexp#names" do
   it "returns an Array" do
-    /foo/.names.should be_an_instance_of(Array)
+    /foo/.names.should.instance_of?(Array)
   end
 
   it "returns an empty Array if there are no named captures" do
@@ -11,7 +11,7 @@ describe "Regexp#names" do
 
   it "returns each named capture as a String" do
     /n(?<cap>ee)d(?<ture>le)/.names.each do |name|
-      name.should be_an_instance_of(String)
+      name.should.instance_of?(String)
     end
   end
 
diff --git a/spec/ruby/core/regexp/new_spec.rb b/spec/ruby/core/regexp/new_spec.rb
index d2d867b3d3..79210e9a23 100644
--- a/spec/ruby/core/regexp/new_spec.rb
+++ b/spec/ruby/core/regexp/new_spec.rb
@@ -7,21 +7,13 @@ end
 
 describe "Regexp.new given a String" do
   it_behaves_like :regexp_new_string, :new
+  it_behaves_like :regexp_new_string_binary, :new
 end
 
 describe "Regexp.new given a Regexp" do
   it_behaves_like :regexp_new_regexp, :new
-  it_behaves_like :regexp_new_string_binary, :compile
 end
 
-describe "Regexp.new given a Fixnum" do
-  it "raises a TypeError" do
-    -> { Regexp.new(1) }.should raise_error(TypeError)
-  end
-end
-
-describe "Regexp.new given a Float" do
-  it "raises a TypeError" do
-    -> { Regexp.new(1.0) }.should raise_error(TypeError)
-  end
+describe "Regexp.new given a non-String/Regexp" do
+  it_behaves_like :regexp_new_non_string_or_regexp, :new
 end
diff --git a/spec/ruby/core/regexp/options_spec.rb b/spec/ruby/core/regexp/options_spec.rb
index fb4853a014..c3401cee6e 100644
--- a/spec/ruby/core/regexp/options_spec.rb
+++ b/spec/ruby/core/regexp/options_spec.rb
@@ -1,10 +1,10 @@
 require_relative '../../spec_helper'
 
 describe "Regexp#options" do
-  it "returns a Fixnum bitvector of regexp options for the Regexp object" do
-    /cat/.options.should be_kind_of(Fixnum)
+  it "returns an Integer bitvector of regexp options for the Regexp object" do
+    /cat/.options.should.is_a?(Integer)
     not_supported_on :opal do
-      /cat/ix.options.should be_kind_of(Fixnum)
+      /cat/ix.options.should.is_a?(Integer)
     end
   end
 
@@ -29,7 +29,7 @@ describe "Regexp#options" do
   end
 
   it "raises a TypeError on an uninitialized Regexp" do
-    -> { Regexp.allocate.options }.should raise_error(TypeError)
+    -> { Regexp.allocate.options }.should.raise(TypeError)
   end
 
   it "includes Regexp::FIXEDENCODING for a Regexp literal with the 'u' option" do
diff --git a/spec/ruby/core/regexp/shared/new.rb b/spec/ruby/core/regexp/shared/new.rb
index bb5df7bc2e..affdaf855c 100644
--- a/spec/ruby/core/regexp/shared/new.rb
+++ b/spec/ruby/core/regexp/shared/new.rb
@@ -1,10 +1,16 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :regexp_new, shared: true do
   it "requires one argument and creates a new regular expression object" do
     Regexp.send(@method, '').is_a?(Regexp).should == true
   end
 
+  ruby_version_is "4.1" do
+    it "is frozen" do
+      Regexp.send(@method, '').should.frozen?
+    end
+  end
+
   it "works by default for subclasses with overridden #initialize" do
     class RegexpSpecsSubclass < Regexp
       def initialize(*args)
@@ -17,10 +23,36 @@ describe :regexp_new, shared: true do
 
     class RegexpSpecsSubclassTwo < Regexp; end
 
-    RegexpSpecsSubclass.send(@method, "hi").should be_kind_of(RegexpSpecsSubclass)
+    RegexpSpecsSubclass.send(@method, "hi").should.is_a?(RegexpSpecsSubclass)
     RegexpSpecsSubclass.send(@method, "hi").args.first.should == "hi"
 
-    RegexpSpecsSubclassTwo.send(@method, "hi").should be_kind_of(RegexpSpecsSubclassTwo)
+    RegexpSpecsSubclassTwo.send(@method, "hi").should.is_a?(RegexpSpecsSubclassTwo)
+  end
+end
+
+describe :regexp_new_non_string_or_regexp, shared: true do
+  it "calls #to_str method for non-String/Regexp argument" do
+    obj = Object.new
+    def obj.to_str() "a" end
+
+    Regexp.send(@method, obj).should == /a/
+  end
+
+  it "raises TypeError if there is no #to_str method for non-String/Regexp argument" do
+    obj = Object.new
+    -> { Regexp.send(@method, obj) }.should.raise(TypeError, "no implicit conversion of Object into String")
+
+    -> { Regexp.send(@method, 1) }.should.raise(TypeError, "no implicit conversion of Integer into String")
+    -> { Regexp.send(@method, 1.0) }.should.raise(TypeError, "no implicit conversion of Float into String")
+    -> { Regexp.send(@method, :symbol) }.should.raise(TypeError, "no implicit conversion of Symbol into String")
+    -> { Regexp.send(@method, []) }.should.raise(TypeError, "no implicit conversion of Array into String")
+  end
+
+  it "raises TypeError if #to_str returns non-String value" do
+    obj = Object.new
+    def obj.to_str() [] end
+
+    -> { Regexp.send(@method, obj) }.should raise_consistent_error(TypeError, /can't convert Object into String/)
   end
 end
 
@@ -30,7 +62,7 @@ describe :regexp_new_string, shared: true do
   end
 
   it "raises a RegexpError when passed an incorrect regexp" do
-    -> { Regexp.send(@method, "^[$", 0) }.should raise_error(RegexpError)
+    -> { Regexp.send(@method, "^[$", 0) }.should.raise(RegexpError, Regexp.new(Regexp.escape("premature end of char-class: /^[$/")))
   end
 
   it "does not set Regexp options if only given one argument" do
@@ -58,7 +90,16 @@ describe :regexp_new_string, shared: true do
     end
   end
 
-  it "sets options from second argument if it is one of the Fixnum option constants" do
+  it "sets options from second argument if it is true" do
+    r = Regexp.send(@method, 'Hi', true)
+    (r.options & Regexp::IGNORECASE).should_not == 0
+    (r.options & Regexp::MULTILINE).should == 0
+    not_supported_on :opal do
+      (r.options & Regexp::EXTENDED).should == 0
+    end
+  end
+
+  it "sets options from second argument if it is one of the Integer option constants" do
     r = Regexp.send(@method, 'Hi', Regexp::IGNORECASE)
     (r.options & Regexp::IGNORECASE).should_not == 0
     (r.options & Regexp::MULTILINE).should == 0
@@ -81,15 +122,30 @@ describe :regexp_new_string, shared: true do
     end
   end
 
-  it "accepts a Fixnum of two or more options ORed together as the second argument" do
+  it "accepts an Integer of two or more options ORed together as the second argument" do
     r = Regexp.send(@method, 'Hi', Regexp::IGNORECASE | Regexp::EXTENDED)
     (r.options & Regexp::IGNORECASE).should_not == 0
     (r.options & Regexp::MULTILINE).should == 0
     (r.options & Regexp::EXTENDED).should_not == 0
   end
 
-  it "treats any non-Fixnum, non-nil, non-false second argument as IGNORECASE" do
-    r = Regexp.send(@method, 'Hi', Object.new)
+  it "does not try to convert the second argument to Integer with #to_int method call" do
+    ScratchPad.clear
+    obj = Object.new
+    def obj.to_int() ScratchPad.record(:called) end
+
+    -> {
+      Regexp.send(@method, "Hi", obj)
+    }.should complain(/expected true or false as ignorecase/, {verbose: true})
+
+    ScratchPad.recorded.should == nil
+  end
+
+  it "warns any non-Integer, non-nil, non-false second argument" do
+    r = nil
+    -> {
+      r = Regexp.send(@method, 'Hi', Object.new)
+    }.should complain(/expected true or false as ignorecase/, {verbose: true})
     (r.options & Regexp::IGNORECASE).should_not == 0
     (r.options & Regexp::MULTILINE).should == 0
     not_supported_on :opal do
@@ -97,249 +153,76 @@ describe :regexp_new_string, shared: true do
     end
   end
 
-  it "ignores the third argument if it is 'e' or 'euc' (case-insensitive)" do
-    -> {
-      Regexp.send(@method, 'Hi', nil, 'e').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'euc').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'E').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'EUC').encoding.should == Encoding::US_ASCII
-    }.should complain(/encoding option is ignored/)
-  end
+  it "accepts a String of supported flags as the second argument" do
+    r = Regexp.send(@method, 'Hi', 'i')
+    (r.options & Regexp::IGNORECASE).should_not == 0
+    (r.options & Regexp::MULTILINE).should == 0
+    not_supported_on :opal do
+      (r.options & Regexp::EXTENDED).should == 0
+    end
 
-  it "ignores the third argument if it is 's' or 'sjis' (case-insensitive)" do
-    -> {
-      Regexp.send(@method, 'Hi', nil, 's').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'sjis').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'S').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'SJIS').encoding.should == Encoding::US_ASCII
-    }.should complain(/encoding option is ignored/)
-  end
+    r = Regexp.send(@method, 'Hi', 'imx')
+    (r.options & Regexp::IGNORECASE).should_not == 0
+    (r.options & Regexp::MULTILINE).should_not == 0
+    not_supported_on :opal do
+      (r.options & Regexp::EXTENDED).should_not == 0
+    end
 
-  it "ignores the third argument if it is 'u' or 'utf8' (case-insensitive)" do
-    -> {
-      Regexp.send(@method, 'Hi', nil, 'u').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'utf8').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'U').encoding.should == Encoding::US_ASCII
-      Regexp.send(@method, 'Hi', nil, 'UTF8').encoding.should == Encoding::US_ASCII
-    }.should complain(/encoding option is ignored/)
-  end
+    r = Regexp.send(@method, 'Hi', 'mimi')
+    (r.options & Regexp::IGNORECASE).should_not == 0
+    (r.options & Regexp::MULTILINE).should_not == 0
+    not_supported_on :opal do
+      (r.options & Regexp::EXTENDED).should == 0
+    end
 
-  it "uses US_ASCII encoding if third argument is 'n' or 'none' (case insensitive) and only ascii characters" do
-    Regexp.send(@method, 'Hi', nil, 'n').encoding.should == Encoding::US_ASCII
-    Regexp.send(@method, 'Hi', nil, 'none').encoding.should == Encoding::US_ASCII
-    Regexp.send(@method, 'Hi', nil, 'N').encoding.should == Encoding::US_ASCII
-    Regexp.send(@method, 'Hi', nil, 'NONE').encoding.should == Encoding::US_ASCII
+    r = Regexp.send(@method, 'Hi', '')
+    (r.options & Regexp::IGNORECASE).should == 0
+    (r.options & Regexp::MULTILINE).should == 0
+    not_supported_on :opal do
+      (r.options & Regexp::EXTENDED).should == 0
+    end
   end
 
-  it "uses ASCII_8BIT encoding if third argument is 'n' or 'none' (case insensitive) and non-ascii characters" do
-    a = "(?:[\x8E\xA1-\xFE])"
-    str = "\A(?:#{a}|x*)\z"
-
-    Regexp.send(@method, str, nil, 'N').encoding.should == Encoding::BINARY
-    Regexp.send(@method, str, nil, 'n').encoding.should == Encoding::BINARY
-    Regexp.send(@method, str, nil, 'none').encoding.should == Encoding::BINARY
-    Regexp.send(@method, str, nil, 'NONE').encoding.should == Encoding::BINARY
+  it "raises an Argument error if the second argument contains unsupported chars" do
+    -> { Regexp.send(@method, 'Hi', 'e') }.should.raise(ArgumentError, "unknown regexp option: e")
+    -> { Regexp.send(@method, 'Hi', 'n') }.should.raise(ArgumentError, "unknown regexp option: n")
+    -> { Regexp.send(@method, 'Hi', 's') }.should.raise(ArgumentError, "unknown regexp option: s")
+    -> { Regexp.send(@method, 'Hi', 'u') }.should.raise(ArgumentError, "unknown regexp option: u")
+    -> { Regexp.send(@method, 'Hi', 'j') }.should.raise(ArgumentError, "unknown regexp option: j")
+    -> { Regexp.send(@method, 'Hi', 'mjx') }.should.raise(ArgumentError, /unknown regexp option: mjx\b/)
   end
 
   describe "with escaped characters" do
     it "raises a Regexp error if there is a trailing backslash" do
-      -> { Regexp.send(@method, "\\") }.should raise_error(RegexpError)
+      -> { Regexp.send(@method, "\\") }.should.raise(RegexpError, Regexp.new(Regexp.escape("too short escape sequence: /\\/")))
     end
 
     it "does not raise a Regexp error if there is an escaped trailing backslash" do
-      -> { Regexp.send(@method, "\\\\") }.should_not raise_error(RegexpError)
+      -> { Regexp.send(@method, "\\\\") }.should_not.raise(RegexpError)
     end
 
-    it "accepts a backspace followed by a character" do
+    it "accepts a backspace followed by a non-special character" do
       Regexp.send(@method, "\\N").should == /#{"\x5c"+"N"}/
     end
 
-    it "accepts a one-digit octal value" do
-      Regexp.send(@method, "\0").should == /#{"\x00"}/
-    end
-
-    it "accepts a two-digit octal value" do
-      Regexp.send(@method, "\11").should == /#{"\x09"}/
-    end
-
-    it "accepts a one-digit hexadecimal value" do
-      Regexp.send(@method, "\x9n").should == /#{"\x09n"}/
-    end
-
-    it "accepts a two-digit hexadecimal value" do
-      Regexp.send(@method, "\x23").should == /#{"\x23"}/
-    end
-
-    it "interprets a digit following a two-digit hexadecimal value as a character" do
-      Regexp.send(@method, "\x420").should == /#{"\x420"}/
-    end
-
     it "raises a RegexpError if \\x is not followed by any hexadecimal digits" do
-      -> { Regexp.send(@method, "\\" + "xn") }.should raise_error(RegexpError)
-    end
-
-    it "accepts an escaped string interpolation" do
-      Regexp.send(@method, "\#{abc}").should == /#{"\#{abc}"}/
-    end
-
-    it "accepts '\\n'" do
-      Regexp.send(@method, "\n").should == /#{"\x0a"}/
-    end
-
-    it "accepts '\\t'" do
-      Regexp.send(@method, "\t").should == /#{"\x09"}/
-    end
-
-    it "accepts '\\r'" do
-      Regexp.send(@method, "\r").should == /#{"\x0d"}/
-    end
-
-    it "accepts '\\f'" do
-      Regexp.send(@method, "\f").should == /#{"\x0c"}/
-    end
-
-    it "accepts '\\v'" do
-      Regexp.send(@method, "\v").should == /#{"\x0b"}/
-    end
-
-    it "accepts '\\a'" do
-      Regexp.send(@method, "\a").should == /#{"\x07"}/
-    end
-
-    it "accepts '\\e'" do
-      Regexp.send(@method, "\e").should == /#{"\x1b"}/
-    end
-
-    it "accepts '\\C-\\n'" do
-      Regexp.send(@method, "\C-\n").should == /#{"\x0a"}/
-    end
-
-    it "accepts '\\C-\\t'" do
-      Regexp.send(@method, "\C-\t").should == /#{"\x09"}/
-    end
-
-    it "accepts '\\C-\\r'" do
-      Regexp.send(@method, "\C-\r").should == /#{"\x0d"}/
-    end
-
-    it "accepts '\\C-\\f'" do
-      Regexp.send(@method, "\C-\f").should == /#{"\x0c"}/
-    end
-
-    it "accepts '\\C-\\v'" do
-      Regexp.send(@method, "\C-\v").should == /#{"\x0b"}/
-    end
-
-    it "accepts '\\C-\\a'" do
-      Regexp.send(@method, "\C-\a").should == /#{"\x07"}/
-    end
-
-    it "accepts '\\C-\\e'" do
-      Regexp.send(@method, "\C-\e").should == /#{"\x1b"}/
-    end
-
-    it "accepts multiple consecutive '\\' characters" do
-      Regexp.send(@method, "\\\\\\N").should == /#{"\\\\\\"+"N"}/
-    end
-
-    it "accepts characters and escaped octal digits" do
-      Regexp.send(@method, "abc\076").should == /#{"abc\x3e"}/
-    end
-
-    it "accepts escaped octal digits and characters" do
-      Regexp.send(@method, "\076abc").should == /#{"\x3eabc"}/
-    end
-
-    it "accepts characters and escaped hexadecimal digits" do
-      Regexp.send(@method, "abc\x42").should == /#{"abc\x42"}/
-    end
-
-    it "accepts escaped hexadecimal digits and characters" do
-      Regexp.send(@method, "\x3eabc").should == /#{"\x3eabc"}/
-    end
-
-    it "accepts escaped hexadecimal and octal digits" do
-      Regexp.send(@method, "\061\x42").should == /#{"\x31\x42"}/
-    end
-
-    it "accepts \\u{H} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{f}").should == /#{"\x0f"}/
-    end
-
-    it "accepts \\u{HH} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{7f}").should == /#{"\x7f"}/
-    end
-
-    it "accepts \\u{HHH} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{07f}").should == /#{"\x7f"}/
-    end
-
-    it "accepts \\u{HHHH} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{0000}").should == /#{"\x00"}/
-    end
-
-    it "accepts \\u{HHHHH} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{00001}").should == /#{"\x01"}/
-    end
-
-    it "accepts \\u{HHHHHH} for a single Unicode codepoint" do
-      Regexp.send(@method, "\u{000000}").should == /#{"\x00"}/
-    end
-
-    it "accepts characters followed by \\u{HHHH}" do
-      Regexp.send(@method, "abc\u{3042}").should == /#{"abc\u3042"}/
-    end
-
-    it "accepts \\u{HHHH} followed by characters" do
-      Regexp.send(@method, "\u{3042}abc").should == /#{"\u3042abc"}/
-    end
-
-    it "accepts escaped hexadecimal digits followed by \\u{HHHH}" do
-      Regexp.send(@method, "\x42\u{3042}").should == /#{"\x42\u3042"}/
-    end
-
-    it "accepts escaped octal digits followed by \\u{HHHH}" do
-      Regexp.send(@method, "\056\u{3042}").should == /#{"\x2e\u3042"}/
-    end
-
-    it "accepts a combination of escaped octal and hexadecimal digits and \\u{HHHH}" do
-      Regexp.send(@method, "\056\x42\u{3042}\x52\076").should == /#{"\x2e\x42\u3042\x52\x3e"}/
-    end
-
-    it "accepts \\uHHHH for a single Unicode codepoint" do
-      Regexp.send(@method, "\u3042").should == /#{"\u3042"}/
-    end
-
-    it "accepts characters followed by \\uHHHH" do
-      Regexp.send(@method, "abc\u3042").should == /#{"abc\u3042"}/
-    end
-
-    it "accepts \\uHHHH followed by characters" do
-      Regexp.send(@method, "\u3042abc").should == /#{"\u3042abc"}/
-    end
-
-    it "accepts escaped hexadecimal digits followed by \\uHHHH" do
-      Regexp.send(@method, "\x42\u3042").should == /#{"\x42\u3042"}/
-    end
-
-    it "accepts escaped octal digits followed by \\uHHHH" do
-      Regexp.send(@method, "\056\u3042").should == /#{"\x2e\u3042"}/
-    end
-
-    it "accepts a combination of escaped octal and hexadecimal digits and \\uHHHH" do
-      Regexp.send(@method, "\056\x42\u3042\x52\076").should == /#{"\x2e\x42\u3042\x52\x3e"}/
+      -> { Regexp.send(@method, "\\" + "xn") }.should.raise(RegexpError, Regexp.new(Regexp.escape("invalid hex escape: /\\xn/")))
     end
 
     it "raises a RegexpError if less than four digits are given for \\uHHHH" do
-      -> { Regexp.send(@method, "\\" + "u304") }.should raise_error(RegexpError)
+      -> { Regexp.send(@method, "\\" + "u304") }.should.raise(RegexpError, Regexp.new(Regexp.escape("invalid Unicode escape: /\\u304/")))
     end
 
     it "raises a RegexpError if the \\u{} escape is empty" do
-      -> { Regexp.send(@method, "\\" + "u{}") }.should raise_error(RegexpError)
+      -> { Regexp.send(@method, "\\" + "u{}") }.should.raise(RegexpError, Regexp.new(Regexp.escape("invalid Unicode list: /\\u{}/")))
+    end
+
+    it "raises a RegexpError if the \\u{} escape contains non hexadecimal digits" do
+      -> { Regexp.send(@method, "\\" + "u{abcX}") }.should.raise(RegexpError, Regexp.new(Regexp.escape("invalid Unicode list: /\\u{abcX}/")))
     end
 
     it "raises a RegexpError if more than six hexadecimal digits are given" do
-      -> { Regexp.send(@method, "\\" + "u{0ffffff}") }.should raise_error(RegexpError)
+      -> { Regexp.send(@method, "\\" + "u{0ffffff}") }.should.raise(RegexpError, Regexp.new(Regexp.escape("invalid Unicode range: /\\u{0ffffff}/")))
     end
 
     it "returns a Regexp with US-ASCII encoding if only 7-bit ASCII characters are present regardless of the input String's encoding" do
@@ -367,12 +250,12 @@ describe :regexp_new_string, shared: true do
     end
 
     it "returns a Regexp with the input String's encoding" do
-      str = "\x82\xa0".force_encoding(Encoding::Shift_JIS)
+      str = "\x82\xa0".dup.force_encoding(Encoding::Shift_JIS)
       Regexp.send(@method, str).encoding.should == Encoding::Shift_JIS
     end
 
     it "returns a Regexp with source String having the input String's encoding" do
-      str = "\x82\xa0".force_encoding(Encoding::Shift_JIS)
+      str = "\x82\xa0".dup.force_encoding(Encoding::Shift_JIS)
       Regexp.send(@method, str).source.encoding.should == Encoding::Shift_JIS
     end
   end
@@ -380,69 +263,6 @@ end
 
 describe :regexp_new_string_binary, shared: true do
   describe "with escaped characters" do
-    it "accepts a three-digit octal value" do
-      Regexp.send(@method, "\315").should == /#{"\xcd"}/
-    end
-
-    it "interprets a digit following a three-digit octal value as a character" do
-      Regexp.send(@method, "\3762").should == /#{"\xfe2"}/
-    end
-
-    it "accepts '\\M-\\n'" do
-      Regexp.send(@method, "\M-\n").should == /#{"\x8a"}/
-    end
-
-    it "accepts '\\M-\\t'" do
-      Regexp.send(@method, "\M-\t").should == /#{"\x89"}/
-    end
-
-    it "accepts '\\M-\\r'" do
-      Regexp.send(@method, "\M-\r").should == /#{"\x8d"}/
-    end
-
-    it "accepts '\\M-\\f'" do
-      Regexp.send(@method, "\M-\f").should == /#{"\x8c"}/
-    end
-
-    it "accepts '\\M-\\v'" do
-      Regexp.send(@method, "\M-\v").should == /#{"\x8b"}/
-    end
-
-    it "accepts '\\M-\\a'" do
-      Regexp.send(@method, "\M-\a").should == /#{"\x87"}/
-    end
-
-    it "accepts '\\M-\\e'" do
-      Regexp.send(@method, "\M-\e").should == /#{"\x9b"}/
-    end
-
-    it "accepts '\\M-\\C-\\n'" do
-      Regexp.send(@method, "\M-\C-\n").should == /#{"\x8a"}/
-    end
-
-    it "accepts '\\M-\\C-\\t'" do
-      Regexp.send(@method, "\M-\C-\t").should == /#{"\x89"}/
-    end
-
-    it "accepts '\\M-\\C-\\r'" do
-      Regexp.send(@method, "\M-\C-\r").should == /#{"\x8d"}/
-    end
-
-    it "accepts '\\M-\\C-\\f'" do
-      Regexp.send(@method, "\M-\C-\f").should == /#{"\x8c"}/
-    end
-
-    it "accepts '\\M-\\C-\\v'" do
-      Regexp.send(@method, "\M-\C-\v").should == /#{"\x8b"}/
-    end
-
-    it "accepts '\\M-\\C-\\a'" do
-      Regexp.send(@method, "\M-\C-\a").should == /#{"\x87"}/
-    end
-
-    it "accepts '\\M-\\C-\\e'" do
-      Regexp.send(@method, "\M-\C-\e").should == /#{"\x9b"}/
-    end
   end
 end
 
@@ -497,9 +317,5 @@ describe :regexp_new_regexp, shared: true do
     it "sets the encoding to US-ASCII if the Regexp literal has the 'n' option and the source String is ASCII only" do
       Regexp.send(@method, /Hi/n).encoding.should == Encoding::US_ASCII
     end
-
-    it "sets the encoding to source String's encoding if the Regexp literal has the 'n' option and the source String is not ASCII only" do
-      Regexp.send(@method, Regexp.new("\\xff", nil, 'n')).encoding.should == Encoding::BINARY
-    end
   end
 end
diff --git a/spec/ruby/core/regexp/shared/quote.rb b/spec/ruby/core/regexp/shared/quote.rb
index a55adb5bf2..083f12d78c 100644
--- a/spec/ruby/core/regexp/shared/quote.rb
+++ b/spec/ruby/core/regexp/shared/quote.rb
@@ -1,9 +1,9 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :regexp_quote, shared: true do
   it "escapes any characters with special meaning in a regular expression" do
-    Regexp.send(@method, '\*?{}.+^[]()- ').should == '\\\\\*\?\{\}\.\+\^\[\]\(\)\-\\ '
-    Regexp.send(@method, "\*?{}.+^[]()- ").should == '\\*\\?\\{\\}\\.\\+\\^\\[\\]\\(\\)\\-\\ '
+    Regexp.send(@method, '\*?{}.+^$[]()- ').should == '\\\\\*\?\{\}\.\+\^\$\[\]\(\)\-\\ '
+    Regexp.send(@method, "\*?{}.+^$[]()- ").should == '\\*\\?\\{\\}\\.\\+\\^\\$\\[\\]\\(\\)\\-\\ '
     Regexp.send(@method, '\n\r\f\t').should == '\\\\n\\\\r\\\\f\\\\t'
     Regexp.send(@method, "\n\r\f\t").should == '\\n\\r\\f\\t'
   end
@@ -12,20 +12,30 @@ describe :regexp_quote, shared: true do
     Regexp.send(@method, :symbol).should == 'symbol'
   end
 
+  it "works with substrings" do
+    str = ".+[]()"[1...-1]
+    Regexp.send(@method, str).should == '\+\[\]\('
+  end
+
+  it "works for broken strings" do
+    Regexp.send(@method, "a.\x85b.".dup.force_encoding("US-ASCII")).should =="a\\.\x85b\\.".dup.force_encoding("US-ASCII")
+    Regexp.send(@method, "a.\x80".dup.force_encoding("UTF-8")).should == "a\\.\x80".dup.force_encoding("UTF-8")
+  end
+
   it "sets the encoding of the result to US-ASCII if there are only US-ASCII characters present in the input String" do
-    str = "abc".force_encoding("euc-jp")
+    str = "abc".dup.force_encoding("euc-jp")
     Regexp.send(@method, str).encoding.should == Encoding::US_ASCII
   end
 
   it "sets the encoding of the result to the encoding of the String if any non-US-ASCII characters are present in an input String with valid encoding" do
-    str = "ありがとう".force_encoding("utf-8")
-    str.valid_encoding?.should be_true
+    str = "ありがとう".dup.force_encoding("utf-8")
+    str.valid_encoding?.should == true
     Regexp.send(@method, str).encoding.should == Encoding::UTF_8
   end
 
   it "sets the encoding of the result to BINARY if any non-US-ASCII characters are present in an input String with invalid encoding" do
-    str = "\xff".force_encoding "us-ascii"
-    str.valid_encoding?.should be_false
+    str = "\xff".dup.force_encoding "us-ascii"
+    str.valid_encoding?.should == false
     Regexp.send(@method, "\xff").encoding.should == Encoding::BINARY
   end
 end
diff --git a/spec/ruby/core/regexp/source_spec.rb b/spec/ruby/core/regexp/source_spec.rb
index 709fee49b3..4eebf280f0 100644
--- a/spec/ruby/core/regexp/source_spec.rb
+++ b/spec/ruby/core/regexp/source_spec.rb
@@ -9,21 +9,39 @@ describe "Regexp#source" do
     /x(.)xz/.source.should == "x(.)xz"
   end
 
-  it "will remove escape characters" do
-    /foo\/bar/.source.should == "foo/bar"
+  it "keeps escape sequences as is" do
+    /\x20\+/.source.should == '\x20\+'
+  end
+
+  describe "escaping" do
+    it "keeps escaping of metacharacter" do
+      /\$/.source.should == "\\$"
+    end
+
+    it "keeps escaping of metacharacter used as a terminator" do
+      %r+\++.source.should == "\\+"
+    end
+
+    it "removes escaping of non-metacharacter used as a terminator" do
+      %r@\@@.source.should == "@"
+    end
+
+    it "keeps escaping of non-metacharacter not used as a terminator" do
+      /\@/.source.should == "\\@"
+    end
   end
 
   not_supported_on :opal do
     it "has US-ASCII encoding when created from an ASCII-only \\u{} literal" do
       re = /[\u{20}-\u{7E}]/
-      re.source.encoding.should equal(Encoding::US_ASCII)
+      re.source.encoding.should.equal?(Encoding::US_ASCII)
     end
   end
 
   not_supported_on :opal do
     it "has UTF-8 encoding when created from a non-ASCII-only \\u{} literal" do
       re = /[\u{20}-\u{7EE}]/
-      re.source.encoding.should equal(Encoding::UTF_8)
+      re.source.encoding.should.equal?(Encoding::UTF_8)
     end
   end
 end
diff --git a/spec/ruby/core/regexp/timeout_spec.rb b/spec/ruby/core/regexp/timeout_spec.rb
new file mode 100644
index 0000000000..a1ec475ef3
--- /dev/null
+++ b/spec/ruby/core/regexp/timeout_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper'
+
+describe "Regexp.timeout" do
+  after :each do
+    Regexp.timeout = nil
+  end
+
+  it "returns global timeout" do
+    Regexp.timeout = 3
+    Regexp.timeout.should == 3
+  end
+
+  it "raises Regexp::TimeoutError after global timeout elapsed" do
+    Regexp.timeout = 0.001
+    Regexp.timeout.should == 0.001
+
+    -> {
+      # A typical ReDoS case
+      /^(a*)*$/ =~ "a" * 1000000 + "x"
+    }.should.raise(Regexp::TimeoutError, "regexp match timeout")
+  end
+
+  it "raises Regexp::TimeoutError after timeout keyword value elapsed" do
+    Regexp.timeout = 3 # This should be ignored
+    Regexp.timeout.should == 3
+
+    re = Regexp.new("^a*b?a*$", timeout: 0.001)
+
+    -> {
+      re =~ "a" * 1000000 + "x"
+    }.should.raise(Regexp::TimeoutError, "regexp match timeout")
+  end
+end
diff --git a/spec/ruby/core/regexp/try_convert_spec.rb b/spec/ruby/core/regexp/try_convert_spec.rb
index be567e2130..da5e10adce 100644
--- a/spec/ruby/core/regexp/try_convert_spec.rb
+++ b/spec/ruby/core/regexp/try_convert_spec.rb
@@ -9,7 +9,7 @@ describe "Regexp.try_convert" do
 
   it "returns nil if given an argument that can't be converted to a Regexp" do
     ['', 'glark', [], Object.new, :pat].each do |arg|
-      Regexp.try_convert(arg).should be_nil
+      Regexp.try_convert(arg).should == nil
     end
   end
 
@@ -18,4 +18,10 @@ describe "Regexp.try_convert" do
     rex.should_receive(:to_regexp).and_return(/(p(a)t[e]rn)/)
     Regexp.try_convert(rex).should == /(p(a)t[e]rn)/
   end
+
+  it "raises a TypeError if the object does not return an Regexp from #to_regexp" do
+    obj = mock("regexp")
+    obj.should_receive(:to_regexp).and_return("string")
+    -> { Regexp.try_convert(obj) }.should raise_consistent_error(TypeError, "can't convert MockObject into Regexp (MockObject#to_regexp gives String)")
+  end
 end
diff --git a/spec/ruby/core/regexp/union_spec.rb b/spec/ruby/core/regexp/union_spec.rb
index 81a31d89b3..c0a9d12fed 100644
--- a/spec/ruby/core/regexp/union_spec.rb
+++ b/spec/ruby/core/regexp/union_spec.rb
@@ -43,6 +43,27 @@ describe "Regexp.union" do
     Regexp.union("\u00A9".encode("ISO-8859-1"), "a".encode("UTF-8")).encoding.should == Encoding::ISO_8859_1
   end
 
+  it "returns ASCII-8BIT if the regexp encodings are ASCII-8BIT and at least one has non-ASCII characters" do
+    us_ascii_implicit, us_ascii_explicit, binary = /abc/, /[\x00-\x7f]/n, /[\x80-\xBF]/n
+    us_ascii_implicit.encoding.should == Encoding::US_ASCII
+    us_ascii_explicit.encoding.should == Encoding::US_ASCII
+    binary.encoding.should == Encoding::BINARY
+
+    Regexp.union(us_ascii_implicit, us_ascii_explicit, binary).encoding.should == Encoding::BINARY
+    Regexp.union(us_ascii_implicit, binary, us_ascii_explicit).encoding.should == Encoding::BINARY
+    Regexp.union(us_ascii_explicit, us_ascii_implicit, binary).encoding.should == Encoding::BINARY
+    Regexp.union(us_ascii_explicit, binary, us_ascii_implicit).encoding.should == Encoding::BINARY
+    Regexp.union(binary, us_ascii_implicit, us_ascii_explicit).encoding.should == Encoding::BINARY
+    Regexp.union(binary, us_ascii_explicit, us_ascii_implicit).encoding.should == Encoding::BINARY
+  end
+
+  it "return US-ASCII if all patterns are ASCII-only" do
+    Regexp.union(/abc/e, /def/e).encoding.should == Encoding::US_ASCII
+    Regexp.union(/abc/n, /def/n).encoding.should == Encoding::US_ASCII
+    Regexp.union(/abc/s, /def/s).encoding.should == Encoding::US_ASCII
+    Regexp.union(/abc/u, /def/u).encoding.should == Encoding::US_ASCII
+  end
+
   it "returns a Regexp with UTF-8 if one part is UTF-8" do
     Regexp.union(/probl[éeè]me/i, /help/i).encoding.should == Encoding::UTF_8
   end
@@ -54,83 +75,83 @@ describe "Regexp.union" do
   it "raises ArgumentError if the arguments include conflicting ASCII-incompatible Strings" do
     -> {
       Regexp.union("a".encode("UTF-16LE"), "b".encode("UTF-16BE"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and UTF-16BE')
   end
 
   it "raises ArgumentError if the arguments include conflicting ASCII-incompatible Regexps" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-16LE")),
                    Regexp.new("b".encode("UTF-16BE")))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and UTF-16BE')
   end
 
   it "raises ArgumentError if the arguments include conflicting fixed encoding Regexps" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-8"),    Regexp::FIXEDENCODING),
                    Regexp.new("b".encode("US-ASCII"), Regexp::FIXEDENCODING))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-8 and US-ASCII')
   end
 
   it "raises ArgumentError if the arguments include a fixed encoding Regexp and a String containing non-ASCII-compatible characters in a different encoding" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-8"), Regexp::FIXEDENCODING),
                    "\u00A9".encode("ISO-8859-1"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-8 and ISO-8859-1')
   end
 
   it "raises ArgumentError if the arguments include a String containing non-ASCII-compatible characters and a fixed encoding Regexp in a different encoding" do
     -> {
       Regexp.union("\u00A9".encode("ISO-8859-1"),
                    Regexp.new("a".encode("UTF-8"), Regexp::FIXEDENCODING))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: ISO-8859-1 and UTF-8')
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible String and an ASCII-only String" do
     -> {
       Regexp.union("a".encode("UTF-16LE"), "b".encode("UTF-8"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, /ASCII incompatible encoding: UTF-16LE|incompatible encodings: UTF-16LE and US-ASCII/)
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible Regexp and an ASCII-only String" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-16LE")), "b".encode("UTF-8"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, /ASCII incompatible encoding: UTF-16LE|incompatible encodings: UTF-16LE and US-ASCII/)
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible String and an ASCII-only Regexp" do
     -> {
       Regexp.union("a".encode("UTF-16LE"), Regexp.new("b".encode("UTF-8")))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, /ASCII incompatible encoding: UTF-16LE|incompatible encodings: UTF-16LE and US-ASCII/)
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible Regexp and an ASCII-only Regexp" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-16LE")), Regexp.new("b".encode("UTF-8")))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, /ASCII incompatible encoding: UTF-16LE|incompatible encodings: UTF-16LE and US-ASCII/)
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible String and a String containing non-ASCII-compatible characters in a different encoding" do
     -> {
       Regexp.union("a".encode("UTF-16LE"), "\u00A9".encode("ISO-8859-1"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and ISO-8859-1')
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible Regexp and a String containing non-ASCII-compatible characters in a different encoding" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-16LE")), "\u00A9".encode("ISO-8859-1"))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and ISO-8859-1')
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible String and a Regexp containing non-ASCII-compatible characters in a different encoding" do
     -> {
       Regexp.union("a".encode("UTF-16LE"), Regexp.new("\u00A9".encode("ISO-8859-1")))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and ISO-8859-1')
   end
 
   it "raises ArgumentError if the arguments include an ASCII-incompatible Regexp and a Regexp containing non-ASCII-compatible characters in a different encoding" do
     -> {
       Regexp.union(Regexp.new("a".encode("UTF-16LE")), Regexp.new("\u00A9".encode("ISO-8859-1")))
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, 'incompatible encodings: UTF-16LE and ISO-8859-1')
   end
 
   it "uses to_str to convert arguments (if not Regexp)" do
@@ -139,11 +160,23 @@ describe "Regexp.union" do
     Regexp.union(obj, "bar").should == /foo|bar/
   end
 
+  it "uses to_regexp to convert argument" do
+    obj = mock('pattern')
+    obj.should_receive(:to_regexp).and_return(/foo/)
+    Regexp.union(obj).should == /foo/
+  end
+
+  it "accepts a Symbol as argument" do
+    Regexp.union(:foo).should == /foo/
+  end
+
   it "accepts a single array of patterns as arguments" do
     Regexp.union(["skiing", "sledding"]).should == /skiing|sledding/
     not_supported_on :opal do
       Regexp.union([/dogs/, /cats/i]).should == /(?-mix:dogs)|(?i-mx:cats)/
     end
-    ->{Regexp.union(["skiing", "sledding"], [/dogs/, /cats/i])}.should raise_error(TypeError)
+    -> {
+      Regexp.union(["skiing", "sledding"], [/dogs/, /cats/i])
+    }.should.raise(TypeError, 'no implicit conversion of Array into String')
   end
 end
diff --git a/spec/ruby/core/set/add_spec.rb b/spec/ruby/core/set/add_spec.rb
new file mode 100644
index 0000000000..1ce03b1eab
--- /dev/null
+++ b/spec/ruby/core/set/add_spec.rb
@@ -0,0 +1,34 @@
+require_relative '../../spec_helper'
+require_relative 'shared/add'
+
+describe "Set#add" do
+  it_behaves_like :set_add, :add
+end
+
+describe "Set#add?" do
+  before :each do
+    @set = Set.new
+  end
+
+  it "adds the passed Object to self" do
+    @set.add?("cat")
+    @set.should.include?("cat")
+  end
+
+  it "returns self when the Object has not yet been added to self" do
+    @set.add?("cat").should.equal?(@set)
+  end
+
+  it "returns nil when the Object has already been added to self" do
+    @set.add?("cat")
+    @set.add?("cat").should == nil
+  end
+
+  it "raises RuntimeError when called during iteration" do
+    set = Set[:a, :b, :c, :d, :e, :f]
+    set.each do |_m|
+      -> { set << 1 }.should.raise(RuntimeError, /iteration/)
+    end
+    set.should == Set[:a, :b, :c, :d, :e, :f]
+  end
+end
diff --git a/spec/ruby/core/set/append_spec.rb b/spec/ruby/core/set/append_spec.rb
new file mode 100644
index 0000000000..82d34d9130
--- /dev/null
+++ b/spec/ruby/core/set/append_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/add'
+
+describe "Set#<<" do
+  it_behaves_like :set_add, :<<
+end
diff --git a/spec/ruby/core/set/case_compare_spec.rb b/spec/ruby/core/set/case_compare_spec.rb
new file mode 100644
index 0000000000..3781b1b963
--- /dev/null
+++ b/spec/ruby/core/set/case_compare_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+require_relative 'shared/include'
+
+describe "Set#===" do
+  it_behaves_like :set_include, :===
+
+  it "is an alias for include?" do
+    set = Set.new
+    set.method(:===).should == set.method(:include?)
+  end
+end
diff --git a/spec/ruby/core/set/case_equality_spec.rb b/spec/ruby/core/set/case_equality_spec.rb
new file mode 100644
index 0000000000..19c1fb6b9c
--- /dev/null
+++ b/spec/ruby/core/set/case_equality_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/include'
+
+describe "Set#===" do
+  it_behaves_like :set_include, :===
+end
diff --git a/spec/ruby/core/set/classify_spec.rb b/spec/ruby/core/set/classify_spec.rb
new file mode 100644
index 0000000000..a225ab7cbb
--- /dev/null
+++ b/spec/ruby/core/set/classify_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Set#classify" do
+  before :each do
+    @set = Set["one", "two", "three", "four"]
+  end
+
+  it "yields each Object in self" do
+    res = []
+    @set.classify { |x| res << x }
+    res.sort.should == ["one", "two", "three", "four"].sort
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.classify
+    enum.should.instance_of?(Enumerator)
+
+    classified = enum.each { |x| x.length }
+    classified.should == { 3 => Set["one", "two"], 4 => Set["four"], 5 => Set["three"] }
+  end
+
+  it "classifies the Objects in self based on the block's return value" do
+    classified = @set.classify { |x| x.length }
+    classified.should == { 3 => Set["one", "two"], 4 => Set["four"], 5 => Set["three"] }
+  end
+end
diff --git a/spec/ruby/core/set/clear_spec.rb b/spec/ruby/core/set/clear_spec.rb
new file mode 100644
index 0000000000..c61a0d78f2
--- /dev/null
+++ b/spec/ruby/core/set/clear_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../spec_helper'
+
+describe "Set#clear" do
+  before :each do
+    @set = Set["one", "two", "three", "four"]
+  end
+
+  it "removes all elements from self" do
+    @set.clear
+    @set.should.empty?
+  end
+
+  it "returns self" do
+    @set.clear.should.equal?(@set)
+  end
+end
diff --git a/spec/ruby/core/set/collect_spec.rb b/spec/ruby/core/set/collect_spec.rb
new file mode 100644
index 0000000000..d186f1a0d9
--- /dev/null
+++ b/spec/ruby/core/set/collect_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/collect'
+
+describe "Set#collect!" do
+  it_behaves_like :set_collect_bang, :collect!
+end
diff --git a/spec/ruby/core/set/compare_by_identity_spec.rb b/spec/ruby/core/set/compare_by_identity_spec.rb
new file mode 100644
index 0000000000..458e760da0
--- /dev/null
+++ b/spec/ruby/core/set/compare_by_identity_spec.rb
@@ -0,0 +1,153 @@
+require_relative '../../spec_helper'
+
+describe "Set#compare_by_identity" do
+  it "compares its members by identity" do
+    a = "a"
+    b1 = "b"
+    b2 = b1.dup
+
+    set = Set.new
+    set.compare_by_identity
+    set.merge([a, a, b1, b2])
+    set.to_a.sort.should == [a, b1, b2].sort
+  end
+
+  it "causes future comparisons on the receiver to be made by identity" do
+    elt = [1]
+    set = Set.new
+    set << elt
+    set.member?(elt.dup).should == true
+    set.compare_by_identity
+    set.member?(elt.dup).should == false
+  end
+
+  it "rehashes internally so that old members can be looked up" do
+    set = Set.new
+    (1..10).each { |k| set << k }
+    o = Object.new
+    def o.hash; 123; end
+    set << o
+    set.compare_by_identity
+    set.member?(o).should == true
+  end
+
+  it "returns self" do
+    set = Set.new
+    result = set.compare_by_identity
+    result.should.equal?(set)
+  end
+
+  it "is idempotent and has no effect on an already compare_by_identity set" do
+    set = Set.new.compare_by_identity
+    set << :foo
+    set.compare_by_identity.should.equal?(set)
+    set.should.compare_by_identity?
+    set.to_a.should == [:foo]
+  end
+
+  it "uses the semantics of BasicObject#equal? to determine members identity" do
+    :a.equal?(:a).should == true
+    Set.new.compare_by_identity.merge([:a, :a]).to_a.should == [:a]
+
+    ary1 = [1]
+    ary2 = [1]
+    ary1.equal?(ary2).should == false
+    Set.new.compare_by_identity.merge([ary1, ary2]).to_a.sort.should == [ary1, ary2].sort
+  end
+
+  it "uses #equal? semantics, but doesn't actually call #equal? to determine identity" do
+    set = Set.new.compare_by_identity
+    obj = mock("equal")
+    obj.should_not_receive(:equal?)
+    set << :foo
+    set << obj
+    set.to_a.should == [:foo, obj]
+  end
+
+  it "does not call #hash on members" do
+    elt = mock("element")
+    elt.should_not_receive(:hash)
+    set = Set.new.compare_by_identity
+    set << elt
+    set.member?(elt).should == true
+  end
+
+  it "regards #dup'd objects as having different identities" do
+    a1 = "a"
+    a2 = a1.dup
+
+    set = Set.new.compare_by_identity
+    set.merge([a1, a2])
+    set.to_a.sort.should == [a1, a2].sort
+  end
+
+  it "regards #clone'd objects as having different identities" do
+    a1 = "a"
+    a2 = a1.clone
+
+    set = Set.new.compare_by_identity
+    set.merge([a1, a2])
+    set.to_a.sort.should == [a1, a2].sort
+  end
+
+  ruby_version_is "4.0" do
+    it "raises a FrozenError on frozen sets" do
+      set = Set.new.freeze
+      -> {
+        set.compare_by_identity
+      }.should.raise(FrozenError, /can't modify frozen Set: (#<)?Set(\[|: {)[\]}]>?/)
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "raises a FrozenError on frozen sets" do
+      set = Set.new.freeze
+      -> {
+        set.compare_by_identity
+      }.should.raise(FrozenError, /frozen Hash/)
+    end
+  end
+
+  it "persists over #dups" do
+    set = Set.new.compare_by_identity
+    set << :a
+    set_dup = set.dup
+    set_dup.should == set
+    set_dup << :a
+    set_dup.to_a.should == [:a]
+  end
+
+  it "persists over #clones" do
+    set = Set.new.compare_by_identity
+    set << :a
+    set_clone = set.clone
+    set_clone.should == set
+    set_clone << :a
+    set_clone.to_a.should == [:a]
+  end
+
+  it "is not equal to set what does not compare by identity" do
+    Set.new([1, 2]).should == Set.new([1, 2])
+    Set.new([1, 2]).should_not == Set.new([1, 2]).compare_by_identity
+  end
+end
+
+describe "Set#compare_by_identity?" do
+  it "returns false by default" do
+    Set.new.should_not.compare_by_identity?
+  end
+
+  it "returns true once #compare_by_identity has been invoked on self" do
+    set = Set.new
+    set.compare_by_identity
+    set.should.compare_by_identity?
+  end
+
+  it "returns true when called multiple times on the same set" do
+    set = Set.new
+    set.compare_by_identity
+    set.should.compare_by_identity?
+    set.should.compare_by_identity?
+    set.should.compare_by_identity?
+  end
+end
diff --git a/spec/ruby/core/set/comparison_spec.rb b/spec/ruby/core/set/comparison_spec.rb
new file mode 100644
index 0000000000..eb18a198e5
--- /dev/null
+++ b/spec/ruby/core/set/comparison_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Set#<=>" do
+  it "returns 0 if the sets are equal" do
+    (Set[] <=> Set[]).should == 0
+    (Set[:a, :b, :c] <=> Set[:a, :b, :c]).should == 0
+  end
+
+  it "returns -1 if the set is a proper subset of the other set" do
+    (Set[] <=> Set[1]).should == -1
+    (Set[1, 2] <=> Set[1, 2, 3]).should == -1
+  end
+
+  it "returns +1 if the set is a proper superset of other set" do
+    (Set[1] <=> Set[]).should == +1
+    (Set[1, 2, 3] <=> Set[1, 2]).should == +1
+  end
+
+  it "returns nil if the set has unique elements" do
+    (Set[1, 2, 3] <=> Set[:a, :b, :c]).should == nil
+  end
+
+  it "returns nil when the argument is not set-like" do
+    (Set[] <=> false).should == nil
+  end
+end
diff --git a/spec/ruby/core/set/constructor_spec.rb b/spec/ruby/core/set/constructor_spec.rb
new file mode 100644
index 0000000000..11138f3a5b
--- /dev/null
+++ b/spec/ruby/core/set/constructor_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+describe "Set[]" do
+  it "returns a new Set populated with the passed Objects" do
+    set = Set[1, 2, 3]
+
+    set.instance_of?(Set).should == true
+    set.size.should.eql?(3)
+
+    set.should.include?(1)
+    set.should.include?(2)
+    set.should.include?(3)
+  end
+end
diff --git a/spec/ruby/core/set/delete_if_spec.rb b/spec/ruby/core/set/delete_if_spec.rb
new file mode 100644
index 0000000000..b231dff50d
--- /dev/null
+++ b/spec/ruby/core/set/delete_if_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+
+describe "Set#delete_if" do
+  before :each do
+    @set = Set["one", "two", "three"]
+  end
+
+  it "yields every element of self" do
+    ret = []
+    @set.delete_if { |x| ret << x }
+    ret.sort.should == ["one", "two", "three"].sort
+  end
+
+  it "deletes every element from self for which the passed block returns true" do
+    @set.delete_if { |x| x.size == 3 }
+    @set.size.should.eql?(1)
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+
+  it "returns self" do
+    @set.delete_if { |x| x }.should.equal?(@set)
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.delete_if
+    enum.should.instance_of?(Enumerator)
+
+    enum.each { |x| x.size == 3 }
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+end
diff --git a/spec/ruby/core/set/delete_spec.rb b/spec/ruby/core/set/delete_spec.rb
new file mode 100644
index 0000000000..cdc6dd7b36
--- /dev/null
+++ b/spec/ruby/core/set/delete_spec.rb
@@ -0,0 +1,36 @@
+require_relative '../../spec_helper'
+
+describe "Set#delete" do
+  before :each do
+    @set = Set["a", "b", "c"]
+  end
+
+  it "deletes the passed Object from self" do
+    @set.delete("a")
+    @set.should_not.include?("a")
+  end
+
+  it "returns self" do
+    @set.delete("a").should.equal?(@set)
+    @set.delete("x").should.equal?(@set)
+  end
+end
+
+describe "Set#delete?" do
+  before :each do
+    @set = Set["a", "b", "c"]
+  end
+
+  it "deletes the passed Object from self" do
+    @set.delete?("a")
+    @set.should_not.include?("a")
+  end
+
+  it "returns self when the passed Object is in self" do
+    @set.delete?("a").should.equal?(@set)
+  end
+
+  it "returns nil when the passed Object is not in self" do
+    @set.delete?("x").should == nil
+  end
+end
diff --git a/spec/ruby/core/set/difference_spec.rb b/spec/ruby/core/set/difference_spec.rb
new file mode 100644
index 0000000000..149f946592
--- /dev/null
+++ b/spec/ruby/core/set/difference_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/difference'
+
+describe "Set#difference" do
+  it_behaves_like :set_difference, :difference
+end
diff --git a/spec/ruby/core/set/disjoint_spec.rb b/spec/ruby/core/set/disjoint_spec.rb
new file mode 100644
index 0000000000..d415c21045
--- /dev/null
+++ b/spec/ruby/core/set/disjoint_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+
+describe "Set#disjoint?" do
+  it "returns false when two Sets have at least one element in common" do
+    Set[1, 2].disjoint?(Set[2, 3]).should == false
+  end
+
+  it "returns true when two Sets have no element in common" do
+    Set[1, 2].disjoint?(Set[3, 4]).should == true
+  end
+
+  context "when comparing to a Set-like object" do
+    it "returns false when a Set has at least one element in common with a Set-like object" do
+      Set[1, 2].disjoint?(SetSpecs::SetLike.new([2, 3])).should == false
+    end
+
+    it "returns true when a Set has no element in common with a Set-like object" do
+      Set[1, 2].disjoint?(SetSpecs::SetLike.new([3, 4])).should == true
+    end
+  end
+end
diff --git a/spec/ruby/core/set/divide_spec.rb b/spec/ruby/core/set/divide_spec.rb
new file mode 100644
index 0000000000..409a22df75
--- /dev/null
+++ b/spec/ruby/core/set/divide_spec.rb
@@ -0,0 +1,68 @@
+require_relative '../../spec_helper'
+
+describe "Set#divide" do
+  it "divides self into a set of subsets based on the blocks return values" do
+    set = Set["one", "two", "three", "four", "five"].divide { |x| x.length }
+    set.map { |x| x.to_a.sort }.sort.should == [["five", "four"], ["one", "two"], ["three"]]
+  end
+
+  it "yields each Object to the block" do
+    ret = []
+    Set["one", "two", "three", "four", "five"].divide { |x| ret << x }
+    ret.sort.should == ["five", "four", "one", "three", "two"]
+  end
+
+  it "returns an enumerator when not passed a block" do
+    ret = Set[1, 2, 3, 4].divide
+    ret.should.is_a?(Enumerator)
+    ret.each(&:even?).should == Set[Set[1, 3], Set[2, 4]]
+  end
+end
+
+describe "Set#divide when passed a block with an arity of 2" do
+  it "divides self into a set of subsets based on the blocks return values" do
+    set = Set[1, 3, 4, 6, 9, 10, 11].divide { |x, y| (x - y).abs == 1 }
+    set.map{ |x| x.to_a.sort }.sort.should == [[1], [3, 4], [6], [9, 10, 11]]
+  end
+
+  ruby_version_is "4.0" do
+    it "yields each two Object to the block" do
+      ret = []
+      Set[1, 2].divide { |x, y| ret << [x, y] }
+      ret.sort.should == [[1, 2], [2, 1]]
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "yields each two Object to the block" do
+      ret = []
+      Set[1, 2].divide { |x, y| ret << [x, y] }
+      ret.sort.should == [[1, 1], [1, 2], [2, 1], [2, 2]]
+    end
+  end
+
+  it "returns an enumerator when not passed a block" do
+    ret = Set[1, 2, 3, 4].divide
+    ret.should.is_a?(Enumerator)
+    ret.each { |a, b| (a + b).even? }.should == Set[Set[1, 3], Set[2, 4]]
+  end
+end
+
+describe "Set#divide when passed a block with an arity of > 2" do
+  it "only uses the first element if the arity > 2" do
+    set = Set["one", "two", "three", "four", "five"].divide do |x, y, z|
+      y.should == nil
+      z.should == nil
+      x.length
+    end
+    set.map { |x| x.to_a.sort }.sort.should == [["five", "four"], ["one", "two"], ["three"]]
+  end
+
+  it "only uses the first element if the arity = -1" do
+    set = Set["one", "two", "three", "four", "five"].divide do |*xs|
+      xs.size.should == 1
+      xs.first.length
+    end
+    set.map { |x| x.to_a.sort }.sort.should == [["five", "four"], ["one", "two"], ["three"]]
+  end
+end
diff --git a/spec/ruby/core/set/each_spec.rb b/spec/ruby/core/set/each_spec.rb
new file mode 100644
index 0000000000..bdafc99571
--- /dev/null
+++ b/spec/ruby/core/set/each_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Set#each" do
+  before :each do
+    @set = Set[1, 2, 3]
+  end
+
+  it "yields each Object in self" do
+    ret = []
+    @set.each { |x| ret << x }
+    ret.sort.should == [1, 2, 3]
+  end
+
+  it "returns self" do
+    @set.each { |x| x }.should.equal?(@set)
+  end
+
+  it "returns an Enumerator when not passed a block" do
+    enum = @set.each
+    enum.should.instance_of?(Enumerator)
+
+    ret = []
+    enum.each { |x| ret << x }
+    ret.sort.should == [1, 2, 3]
+  end
+end
diff --git a/spec/ruby/core/set/empty_spec.rb b/spec/ruby/core/set/empty_spec.rb
new file mode 100644
index 0000000000..c71f2ce18d
--- /dev/null
+++ b/spec/ruby/core/set/empty_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+
+describe "Set#empty?" do
+  it "returns true if self is empty" do
+    Set[].empty?.should == true
+    Set[1].empty?.should == false
+    Set[1,2,3].empty?.should == false
+  end
+end
diff --git a/spec/ruby/core/set/enumerable/to_set_spec.rb b/spec/ruby/core/set/enumerable/to_set_spec.rb
new file mode 100644
index 0000000000..f139e1c025
--- /dev/null
+++ b/spec/ruby/core/set/enumerable/to_set_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../../spec_helper'
+
+describe "Enumerable#to_set" do
+  it "returns a new Set created from self" do
+    [1, 2, 3].to_set.should == Set[1, 2, 3]
+    {a: 1, b: 2}.to_set.should == Set[[:b, 2], [:a, 1]]
+  end
+
+  it "passes down passed blocks" do
+    [1, 2, 3].to_set { |x| x * x }.should == Set[1, 4, 9]
+  end
+end
diff --git a/spec/ruby/core/set/eql_spec.rb b/spec/ruby/core/set/eql_spec.rb
new file mode 100644
index 0000000000..6862ed4eda
--- /dev/null
+++ b/spec/ruby/core/set/eql_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+describe "Set#eql?" do
+  it "returns true when the passed argument is a Set and contains the same elements" do
+    Set[].should.eql?(Set[])
+    Set[1, 2, 3].should.eql?(Set[1, 2, 3])
+    Set[1, 2, 3].should.eql?(Set[3, 2, 1])
+    Set["a", :b, ?c].should.eql?(Set[?c, :b, "a"])
+
+    Set[1, 2, 3].should_not.eql?(Set[1.0, 2, 3])
+    Set[1, 2, 3].should_not.eql?(Set[2, 3])
+    Set[1, 2, 3].should_not.eql?(Set[])
+  end
+end
diff --git a/spec/ruby/core/set/equal_value_spec.rb b/spec/ruby/core/set/equal_value_spec.rb
new file mode 100644
index 0000000000..721a79a3f1
--- /dev/null
+++ b/spec/ruby/core/set/equal_value_spec.rb
@@ -0,0 +1,34 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+
+describe "Set#==" do
+  it "returns true when the passed Object is a Set and self and the Object contain the same elements" do
+    Set[].should == Set[]
+    Set[1, 2, 3].should == Set[1, 2, 3]
+    Set["1", "2", "3"].should == Set["1", "2", "3"]
+
+    Set[1, 2, 3].should_not == Set[1.0, 2, 3]
+    Set[1, 2, 3].should_not == [1, 2, 3]
+  end
+
+  it "does not depend on the order of the elements" do
+    Set[1, 2, 3].should == Set[3, 2, 1]
+    Set[:a, "b", ?c].should == Set[?c, "b", :a]
+  end
+
+  it "does not depend on the order of nested Sets" do
+    Set[Set[1], Set[2], Set[3]].should == Set[Set[3], Set[2], Set[1]]
+
+    set1 = Set[Set["a", "b"], Set["c", "d"], Set["e", "f"]]
+    set2 = Set[Set["c", "d"], Set["a", "b"], Set["e", "f"]]
+    set1.should == set2
+  end
+
+  ruby_version_is ""..."4.0" do
+    context "when comparing to a Set-like object" do
+      it "returns true when a Set and a Set-like object contain the same elements" do
+        Set[1, 2, 3].should == SetSpecs::SetLike.new([1, 2, 3])
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/set/exclusion_spec.rb b/spec/ruby/core/set/exclusion_spec.rb
new file mode 100644
index 0000000000..52ee34fe78
--- /dev/null
+++ b/spec/ruby/core/set/exclusion_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+
+describe "Set#^" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns a new Set containing elements that are not in both self and the passed Enumerable" do
+    (@set ^ Set[3, 4, 5]).should == Set[1, 2, 5]
+    (@set ^ [3, 4, 5]).should == Set[1, 2, 5]
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { @set ^ 3 }.should.raise(ArgumentError)
+    -> { @set ^ Object.new }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/filter_spec.rb b/spec/ruby/core/set/filter_spec.rb
new file mode 100644
index 0000000000..779254ad68
--- /dev/null
+++ b/spec/ruby/core/set/filter_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/select'
+
+describe "Set#filter!" do
+  it_behaves_like :set_select_bang, :filter!
+end
diff --git a/spec/ruby/core/set/fixtures/set_like.rb b/spec/ruby/core/set/fixtures/set_like.rb
new file mode 100644
index 0000000000..86dec2ed52
--- /dev/null
+++ b/spec/ruby/core/set/fixtures/set_like.rb
@@ -0,0 +1,30 @@
+
+module SetSpecs
+  # This class is used to test the interaction of "Set-like" objects with real Sets
+  #
+  # These "Set-like" objects reply to is_a?(Set) with true and thus real Set objects are able to transparently
+  # interoperate with them in a duck-typing manner.
+  class SetLike
+    include Enumerable
+
+    def is_a?(klass)
+      super || klass == ::Set
+    end
+
+    def initialize(entries)
+      @entries = entries
+    end
+
+    def each(&block)
+      @entries.each(&block)
+    end
+
+    def inspect
+      "#<#{self.class}: {#{map(&:inspect).join(", ")}}>"
+    end
+
+    def size
+      @entries.size
+    end
+  end
+end
diff --git a/spec/ruby/core/set/flatten_merge_spec.rb b/spec/ruby/core/set/flatten_merge_spec.rb
new file mode 100644
index 0000000000..3904d969ae
--- /dev/null
+++ b/spec/ruby/core/set/flatten_merge_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+describe "Set#flatten_merge" do
+  ruby_version_is ""..."4.0" do
+    it "is protected" do
+      Set.protected_instance_methods(false).should.include?(:flatten_merge)
+    end
+
+    it "flattens the passed Set and merges it into self" do
+      set1 = Set[1, 2]
+      set2 = Set[3, 4, Set[5, 6]]
+
+      set1.send(:flatten_merge, set2).should == Set[1, 2, 3, 4, 5, 6]
+    end
+
+    it "raises an ArgumentError when trying to flatten a recursive Set" do
+      set1 = Set[1, 2, 3]
+      set2 = Set[5, 6, 7]
+      set2 << set2
+
+      -> { set1.send(:flatten_merge, set2) }.should.raise(ArgumentError)
+    end
+  end
+end
diff --git a/spec/ruby/core/set/flatten_spec.rb b/spec/ruby/core/set/flatten_spec.rb
new file mode 100644
index 0000000000..ca6323fac8
--- /dev/null
+++ b/spec/ruby/core/set/flatten_spec.rb
@@ -0,0 +1,49 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+set_version = defined?(Set::VERSION) ? Set::VERSION : '1.0.0'
+
+describe "Set#flatten" do
+  it "returns a copy of self with each included Set flattened" do
+    set = Set[1, 2, Set[3, 4, Set[5, 6, Set[7, 8]]], 9, 10]
+    flattened_set = set.flatten
+
+    flattened_set.should_not.equal?(set)
+    flattened_set.should == Set[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+  end
+
+  it "raises an ArgumentError when self is recursive" do
+    (set = Set[]) << set
+    -> { set.flatten }.should.raise(ArgumentError)
+  end
+
+  ruby_version_is ""..."4.0" do
+    context "when Set contains a Set-like object" do
+      it "returns a copy of self with each included Set-like object flattened" do
+        Set[SetSpecs::SetLike.new([1])].flatten.should == Set[1]
+      end
+    end
+  end
+end
+
+describe "Set#flatten!" do
+  it "flattens self" do
+    set = Set[1, 2, Set[3, 4, Set[5, 6, Set[7, 8]]], 9, 10]
+    set.flatten!
+    set.should == Set[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+  end
+
+  it "returns self when self was modified" do
+    set = Set[1, 2, Set[3, 4]]
+    set.flatten!.should.equal?(set)
+  end
+
+  it "returns nil when self was not modified" do
+    set = Set[1, 2, 3, 4]
+    set.flatten!.should == nil
+  end
+
+  it "raises an ArgumentError when self is recursive" do
+    (set = Set[]) << set
+    -> { set.flatten! }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/hash_spec.rb b/spec/ruby/core/set/hash_spec.rb
new file mode 100644
index 0000000000..63a0aa66a5
--- /dev/null
+++ b/spec/ruby/core/set/hash_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+
+describe "Set#hash" do
+  it "is static" do
+    Set[].hash.should == Set[].hash
+    Set[1, 2, 3].hash.should == Set[1, 2, 3].hash
+    Set[:a, "b", ?c].hash.should == Set[?c, "b", :a].hash
+
+    Set[].hash.should_not == Set[1, 2, 3].hash
+    Set[1, 2, 3].hash.should_not == Set[:a, "b", ?c].hash
+  end
+
+  ruby_version_is ""..."4.0" do
+    # see https://github.com/jruby/jruby/issues/8393
+    it "is equal to nil.hash for an uninitialized Set" do
+      Set.allocate.hash.should == nil.hash
+    end
+  end
+end
diff --git a/spec/ruby/core/set/include_spec.rb b/spec/ruby/core/set/include_spec.rb
new file mode 100644
index 0000000000..dd33bbc3bd
--- /dev/null
+++ b/spec/ruby/core/set/include_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/include'
+
+describe "Set#include?" do
+  it_behaves_like :set_include, :include?
+end
diff --git a/spec/ruby/core/set/initialize_clone_spec.rb b/spec/ruby/core/set/initialize_clone_spec.rb
new file mode 100644
index 0000000000..13abb7ee4e
--- /dev/null
+++ b/spec/ruby/core/set/initialize_clone_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+
+describe "Set#initialize_clone" do
+  # See https://bugs.ruby-lang.org/issues/14266
+  it "does not freeze the new Set when called from clone(freeze: false)" do
+    set1 = Set[1, 2]
+    set1.freeze
+    set2 = set1.clone(freeze: false)
+    set1.frozen?.should == true
+    set2.frozen?.should == false
+    set2.add 3
+    set1.should == Set[1, 2]
+    set2.should == Set[1, 2, 3]
+  end
+end
diff --git a/spec/ruby/core/set/initialize_spec.rb b/spec/ruby/core/set/initialize_spec.rb
new file mode 100644
index 0000000000..45538b38fb
--- /dev/null
+++ b/spec/ruby/core/set/initialize_spec.rb
@@ -0,0 +1,88 @@
+require_relative '../../spec_helper'
+
+describe "Set#initialize" do
+  it "is private" do
+    Set.private_instance_methods(false).should.include?(:initialize)
+  end
+
+  it "adds all elements of the passed Enumerable to self" do
+    s = Set.new([1, 2, 3])
+    s.size.should.eql?(3)
+    s.should.include?(1)
+    s.should.include?(2)
+    s.should.include?(3)
+  end
+
+  it "uses #each_entry on the provided Enumerable" do
+    enumerable = MockObject.new('mock-enumerable')
+    enumerable.should_receive(:each_entry).and_yield(1).and_yield(2).and_yield(3)
+    s = Set.new(enumerable)
+    s.size.should.eql?(3)
+    s.should.include?(1)
+    s.should.include?(2)
+    s.should.include?(3)
+  end
+
+  it "uses #each on the provided Enumerable if it does not respond to #each_entry" do
+    enumerable = MockObject.new('mock-enumerable')
+    enumerable.should_receive(:each).and_yield(1).and_yield(2).and_yield(3)
+    s = Set.new(enumerable)
+    s.size.should.eql?(3)
+    s.should.include?(1)
+    s.should.include?(2)
+    s.should.include?(3)
+  end
+
+  it "raises if the provided Enumerable does not respond to #each_entry or #each" do
+    enumerable = MockObject.new('mock-enumerable')
+    -> { Set.new(enumerable) }.should.raise(ArgumentError, "value must be enumerable")
+  end
+
+  it "should initialize with empty array and set" do
+    s = Set.new([])
+    s.size.should.eql?(0)
+
+    s = Set.new({})
+    s.size.should.eql?(0)
+  end
+
+  it "preprocesses all elements by a passed block before adding to self" do
+    s = Set.new([1, 2, 3]) { |x| x * x }
+    s.size.should.eql?(3)
+    s.should.include?(1)
+    s.should.include?(4)
+    s.should.include?(9)
+  end
+
+  it "should initialize with empty array and block" do
+    s = Set.new([]) { |x| x * x }
+    s.size.should.eql?(0)
+  end
+
+  it "should initialize with empty set and block" do
+    s = Set.new(Set.new) { |x| x * x }
+    s.size.should.eql?(0)
+  end
+
+  it "should initialize with set" do
+    o = Set.new([1, 2])
+    s = Set.new(o)
+    s.size.should.eql?(2)
+    s.should.include?(1)
+    s.should.include?(2)
+  end
+
+  it "should initialize with set and block" do
+    o = Set.new([1, 2])
+    s = Set.new(o) { |e| e + 2 }
+    s.size.should.eql?(2)
+    s.should.include?(3)
+    s.should.include?(4)
+  end
+
+  it "should initialize with just block" do
+    s = Set.new { |x| x * x }
+    s.size.should.eql?(0)
+    s.should.eql?(Set.new)
+  end
+end
diff --git a/spec/ruby/core/set/inspect_spec.rb b/spec/ruby/core/set/inspect_spec.rb
new file mode 100644
index 0000000000..0dcce83eb6
--- /dev/null
+++ b/spec/ruby/core/set/inspect_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/inspect'
+
+describe "Set#inspect" do
+  it_behaves_like :set_inspect, :inspect
+end
diff --git a/spec/ruby/core/set/intersect_spec.rb b/spec/ruby/core/set/intersect_spec.rb
new file mode 100644
index 0000000000..d04a1af441
--- /dev/null
+++ b/spec/ruby/core/set/intersect_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+
+describe "Set#intersect?" do
+  it "returns true when two Sets have at least one element in common" do
+    Set[1, 2].intersect?(Set[2, 3]).should == true
+  end
+
+  it "returns false when two Sets have no element in common" do
+    Set[1, 2].intersect?(Set[3, 4]).should == false
+  end
+
+  context "when comparing to a Set-like object" do
+    it "returns true when a Set has at least one element in common with a Set-like object" do
+      Set[1, 2].intersect?(SetSpecs::SetLike.new([2, 3])).should == true
+    end
+
+    it "returns false when a Set has no element in common with a Set-like object" do
+      Set[1, 2].intersect?(SetSpecs::SetLike.new([3, 4])).should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/set/intersection_spec.rb b/spec/ruby/core/set/intersection_spec.rb
new file mode 100644
index 0000000000..136b886775
--- /dev/null
+++ b/spec/ruby/core/set/intersection_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+require_relative 'shared/intersection'
+
+describe "Set#intersection" do
+  it_behaves_like :set_intersection, :intersection
+end
+
+describe "Set#&" do
+  it_behaves_like :set_intersection, :&
+end
diff --git a/spec/ruby/core/set/join_spec.rb b/spec/ruby/core/set/join_spec.rb
new file mode 100644
index 0000000000..1c1e8a8af8
--- /dev/null
+++ b/spec/ruby/core/set/join_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+
+describe "Set#join" do
+  it "returns an empty string if the Set is empty" do
+    Set[].join.should == ''
+  end
+
+  it "returns a new string formed by joining elements after conversion" do
+    set = Set[:a, :b, :c]
+    set.join.should == "abc"
+  end
+
+  it "does not separate elements when the passed separator is nil" do
+    set = Set[:a, :b, :c]
+    set.join(nil).should == "abc"
+  end
+
+  it "returns a string formed by concatenating each element separated by the separator" do
+    set = Set[:a, :b, :c]
+    set.join(' | ').should == "a | b | c"
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "calls #to_a to convert the Set in to an Array" do
+      set = Set[:a, :b, :c]
+      set.should_receive(:to_a).and_return([:a, :b, :c])
+      set.join.should == "abc"
+    end
+  end
+end
diff --git a/spec/ruby/core/set/keep_if_spec.rb b/spec/ruby/core/set/keep_if_spec.rb
new file mode 100644
index 0000000000..7ca5d0cd43
--- /dev/null
+++ b/spec/ruby/core/set/keep_if_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+
+describe "Set#keep_if" do
+  before :each do
+    @set = Set["one", "two", "three"]
+  end
+
+  it "yields every element of self" do
+    ret = []
+    @set.keep_if { |x| ret << x }
+    ret.sort.should == ["one", "two", "three"].sort
+  end
+
+  it "keeps every element from self for which the passed block returns true" do
+    @set.keep_if { |x| x.size != 3 }
+    @set.size.should.eql?(1)
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+
+  it "returns self" do
+    @set.keep_if {}.should.equal?(@set)
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.keep_if
+    enum.should.instance_of?(Enumerator)
+
+    enum.each { |x| x.size != 3 }
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+end
diff --git a/spec/ruby/core/set/length_spec.rb b/spec/ruby/core/set/length_spec.rb
new file mode 100644
index 0000000000..6bb697b4ca
--- /dev/null
+++ b/spec/ruby/core/set/length_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/length'
+
+describe "Set#length" do
+  it_behaves_like :set_length, :length
+end
diff --git a/spec/ruby/core/set/map_spec.rb b/spec/ruby/core/set/map_spec.rb
new file mode 100644
index 0000000000..996191b0a8
--- /dev/null
+++ b/spec/ruby/core/set/map_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/collect'
+
+describe "Set#map!" do
+  it_behaves_like :set_collect_bang, :map!
+end
diff --git a/spec/ruby/core/set/member_spec.rb b/spec/ruby/core/set/member_spec.rb
new file mode 100644
index 0000000000..5c82e8f826
--- /dev/null
+++ b/spec/ruby/core/set/member_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/include'
+
+describe "Set#member?" do
+  it_behaves_like :set_include, :member?
+end
diff --git a/spec/ruby/core/set/merge_spec.rb b/spec/ruby/core/set/merge_spec.rb
new file mode 100644
index 0000000000..a2c1a7e706
--- /dev/null
+++ b/spec/ruby/core/set/merge_spec.rb
@@ -0,0 +1,29 @@
+require_relative '../../spec_helper'
+
+describe "Set#merge" do
+  it "adds the elements of the passed Enumerable to self" do
+    Set[:a, :b].merge(Set[:b, :c, :d]).should == Set[:a, :b, :c, :d]
+    Set[1, 2].merge([3, 4]).should == Set[1, 2, 3, 4]
+  end
+
+  it "returns self" do
+    set = Set[1, 2]
+    set.merge([3, 4]).should.equal?(set)
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { Set[1, 2].merge(1) }.should.raise(ArgumentError)
+    -> { Set[1, 2].merge(Object.new) }.should.raise(ArgumentError)
+  end
+
+  it "raises RuntimeError when called during iteration" do
+    set = Set[:a, :b]
+    set.each do |_m|
+      -> { set.merge([1, 2]) }.should.raise(RuntimeError, /iteration/)
+    end
+  end
+
+  it "accepts multiple arguments" do
+    Set[:a, :b].merge(Set[:b, :c], [:d]).should == Set[:a, :b, :c, :d]
+  end
+end
diff --git a/spec/ruby/core/set/minus_spec.rb b/spec/ruby/core/set/minus_spec.rb
new file mode 100644
index 0000000000..72f98f985e
--- /dev/null
+++ b/spec/ruby/core/set/minus_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/difference'
+
+describe "Set#-" do
+  it_behaves_like :set_difference, :-
+end
diff --git a/spec/ruby/core/set/plus_spec.rb b/spec/ruby/core/set/plus_spec.rb
new file mode 100644
index 0000000000..7e44ff0b7e
--- /dev/null
+++ b/spec/ruby/core/set/plus_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/union'
+
+describe "Set#+" do
+  it_behaves_like :set_union, :+
+end
diff --git a/spec/ruby/core/set/pretty_print_cycle_spec.rb b/spec/ruby/core/set/pretty_print_cycle_spec.rb
new file mode 100644
index 0000000000..7e6017c112
--- /dev/null
+++ b/spec/ruby/core/set/pretty_print_cycle_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+
+describe "Set#pretty_print_cycle" do
+  it "passes the 'pretty print' representation of a self-referencing Set to the pretty print writer" do
+    pp = mock("PrettyPrint")
+    ruby_version_is(""..."4.0") do
+      pp.should_receive(:text).with("#<Set: {...}>")
+    end
+    ruby_version_is("4.0") do
+      pp.should_receive(:text).with("Set[...]")
+    end
+    Set[1, 2, 3].pretty_print_cycle(pp)
+  end
+end
diff --git a/spec/ruby/core/set/proper_subset_spec.rb b/spec/ruby/core/set/proper_subset_spec.rb
new file mode 100644
index 0000000000..3fd27da131
--- /dev/null
+++ b/spec/ruby/core/set/proper_subset_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+set_version = defined?(Set::VERSION) ? Set::VERSION : '1.0.0'
+
+describe "Set#proper_subset?" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a Set that self is a proper subset of" do
+    Set[].proper_subset?(@set).should == true
+    Set[].proper_subset?(Set[1, 2, 3]).should == true
+    Set[].proper_subset?(Set["a", :b, ?c]).should == true
+
+    Set[1, 2, 3].proper_subset?(@set).should == true
+    Set[1, 3].proper_subset?(@set).should == true
+    Set[1, 2].proper_subset?(@set).should == true
+    Set[1].proper_subset?(@set).should == true
+
+    Set[5].proper_subset?(@set).should == false
+    Set[1, 5].proper_subset?(@set).should == false
+    Set[nil].proper_subset?(@set).should == false
+    Set["test"].proper_subset?(@set).should == false
+
+    @set.proper_subset?(@set).should == false
+    Set[].proper_subset?(Set[]).should == false
+  end
+
+  it "raises an ArgumentError when passed a non-Set" do
+    -> { Set[].proper_subset?([]) }.should.raise(ArgumentError)
+    -> { Set[].proper_subset?(1) }.should.raise(ArgumentError)
+    -> { Set[].proper_subset?("test") }.should.raise(ArgumentError)
+    -> { Set[].proper_subset?(Object.new) }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/proper_superset_spec.rb b/spec/ruby/core/set/proper_superset_spec.rb
new file mode 100644
index 0000000000..e95c67ef0e
--- /dev/null
+++ b/spec/ruby/core/set/proper_superset_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+
+describe "Set#proper_superset?" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a Set that self is a proper superset of" do
+    @set.proper_superset?(Set[]).should == true
+    Set[1, 2, 3].proper_superset?(Set[]).should == true
+    Set["a", :b, ?c].proper_superset?(Set[]).should == true
+
+    @set.proper_superset?(Set[1, 2, 3]).should == true
+    @set.proper_superset?(Set[1, 3]).should == true
+    @set.proper_superset?(Set[1, 2]).should == true
+    @set.proper_superset?(Set[1]).should == true
+
+    @set.proper_superset?(Set[5]).should == false
+    @set.proper_superset?(Set[1, 5]).should == false
+    @set.proper_superset?(Set[nil]).should == false
+    @set.proper_superset?(Set["test"]).should == false
+
+    @set.proper_superset?(@set).should == false
+    Set[].proper_superset?(Set[]).should == false
+  end
+
+  it "raises an ArgumentError when passed a non-Set" do
+    -> { Set[].proper_superset?([]) }.should.raise(ArgumentError)
+    -> { Set[].proper_superset?(1) }.should.raise(ArgumentError)
+    -> { Set[].proper_superset?("test") }.should.raise(ArgumentError)
+    -> { Set[].proper_superset?(Object.new) }.should.raise(ArgumentError)
+  end
+
+  ruby_version_is ""..."4.0" do
+    context "when comparing to a Set-like object" do
+      it "returns true if passed a Set-like object that self is a proper superset of" do
+        Set[1, 2, 3, 4].proper_superset?(SetSpecs::SetLike.new([1, 2, 3])).should == true
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/set/reject_spec.rb b/spec/ruby/core/set/reject_spec.rb
new file mode 100644
index 0000000000..b00a36812b
--- /dev/null
+++ b/spec/ruby/core/set/reject_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+
+describe "Set#reject!" do
+  before :each do
+    @set = Set["one", "two", "three"]
+  end
+
+  it "yields every element of self" do
+    ret = []
+    @set.reject! { |x| ret << x }
+    ret.sort.should == ["one", "two", "three"].sort
+  end
+
+  it "deletes every element from self for which the passed block returns true" do
+    @set.reject! { |x| x.size == 3 }
+    @set.size.should.eql?(1)
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+
+  it "returns self when self was modified" do
+    @set.reject! { |x| true }.should.equal?(@set)
+  end
+
+  it "returns nil when self was not modified" do
+    @set.reject! { |x| false }.should == nil
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.reject!
+    enum.should.instance_of?(Enumerator)
+
+    enum.each { |x| x.size == 3 }
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+end
diff --git a/spec/ruby/core/set/replace_spec.rb b/spec/ruby/core/set/replace_spec.rb
new file mode 100644
index 0000000000..2a51a024dc
--- /dev/null
+++ b/spec/ruby/core/set/replace_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+describe "Set#replace" do
+  before :each do
+    @set = Set[:a, :b, :c]
+  end
+
+  it "replaces the contents with other and returns self" do
+    @set.replace(Set[1, 2, 3]).should == @set
+    @set.should == Set[1, 2, 3]
+  end
+
+  it "raises RuntimeError when called during iteration" do
+    set = Set[:a, :b, :c, :d, :e, :f]
+    set.each do |_m|
+      -> { set.replace(Set[1, 2, 3]) }.should.raise(RuntimeError, /iteration/)
+    end
+    set.should == Set[:a, :b, :c, :d, :e, :f]
+  end
+
+  it "accepts any enumerable as other" do
+    @set.replace([1, 2, 3]).should == Set[1, 2, 3]
+  end
+end
diff --git a/spec/ruby/library/set/select_spec.rb b/spec/ruby/core/set/select_spec.rb
index b458ffacaa..b458ffacaa 100644
--- a/spec/ruby/library/set/select_spec.rb
+++ b/spec/ruby/core/set/select_spec.rb
diff --git a/spec/ruby/core/set/set_spec.rb b/spec/ruby/core/set/set_spec.rb
new file mode 100644
index 0000000000..fd1d2072e3
--- /dev/null
+++ b/spec/ruby/core/set/set_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+
+describe 'Set' do
+  it 'is available without explicit requiring' do
+    output = ruby_exe(<<~RUBY, options: '--disable-gems', args: '2>&1')
+      puts Set.new([1, 2, 3]).to_a.inspect
+    RUBY
+    output.chomp.should == "[1, 2, 3]"
+  end
+end
diff --git a/spec/ruby/core/set/shared/add.rb b/spec/ruby/core/set/shared/add.rb
new file mode 100644
index 0000000000..8d6d83434f
--- /dev/null
+++ b/spec/ruby/core/set/shared/add.rb
@@ -0,0 +1,14 @@
+describe :set_add, shared: true do
+  before :each do
+    @set = Set.new
+  end
+
+  it "adds the passed Object to self" do
+    @set.send(@method, "dog")
+    @set.should.include?("dog")
+  end
+
+  it "returns self" do
+    @set.send(@method, "dog").should.equal?(@set)
+  end
+end
diff --git a/spec/ruby/core/set/shared/collect.rb b/spec/ruby/core/set/shared/collect.rb
new file mode 100644
index 0000000000..ad5c5afa59
--- /dev/null
+++ b/spec/ruby/core/set/shared/collect.rb
@@ -0,0 +1,20 @@
+describe :set_collect_bang, shared: true do
+  before :each do
+    @set = Set[1, 2, 3, 4, 5]
+  end
+
+  it "yields each Object in self" do
+    res = []
+    @set.send(@method) { |x| res << x }
+    res.sort.should == [1, 2, 3, 4, 5].sort
+  end
+
+  it "returns self" do
+    @set.send(@method) { |x| x }.should.equal?(@set)
+  end
+
+  it "replaces self with the return values of the block" do
+    @set.send(@method) { |x| x * 2 }
+    @set.should == Set[2, 4, 6, 8, 10]
+  end
+end
diff --git a/spec/ruby/core/set/shared/difference.rb b/spec/ruby/core/set/shared/difference.rb
new file mode 100644
index 0000000000..8a17056a82
--- /dev/null
+++ b/spec/ruby/core/set/shared/difference.rb
@@ -0,0 +1,15 @@
+describe :set_difference, shared: true do
+  before :each do
+    @set = Set[:a, :b, :c]
+  end
+
+  it "returns a new Set containing self's elements excluding the elements in the passed Enumerable" do
+    @set.send(@method, Set[:a, :b]).should == Set[:c]
+    @set.send(@method, [:b, :c]).should == Set[:a]
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { @set.send(@method, 1) }.should.raise(ArgumentError)
+    -> { @set.send(@method, Object.new) }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/shared/include.rb b/spec/ruby/core/set/shared/include.rb
new file mode 100644
index 0000000000..82755ccf59
--- /dev/null
+++ b/spec/ruby/core/set/shared/include.rb
@@ -0,0 +1,29 @@
+describe :set_include, shared: true do
+  it "returns true when self contains the passed Object" do
+    set = Set[:a, :b, :c]
+    set.send(@method, :a).should == true
+    set.send(@method, :e).should == false
+  end
+
+  describe "member equality" do
+    it "is checked using both #hash and #eql?" do
+      obj = Object.new
+      obj_another = Object.new
+
+      def obj.hash; 42 end
+      def obj_another.hash; 42 end
+      def obj_another.eql?(o) hash == o.hash end
+
+      set = Set["a", "b", "c", obj]
+      set.send(@method, obj_another).should == true
+    end
+
+    it "is not checked using #==" do
+      obj = Object.new
+      set = Set["a", "b", "c"]
+
+      obj.should_not_receive(:==)
+      set.send(@method, obj)
+    end
+  end
+end
diff --git a/spec/ruby/core/set/shared/inspect.rb b/spec/ruby/core/set/shared/inspect.rb
new file mode 100644
index 0000000000..31bd8accfd
--- /dev/null
+++ b/spec/ruby/core/set/shared/inspect.rb
@@ -0,0 +1,45 @@
+describe :set_inspect, shared: true do
+  it "returns a String representation of self" do
+    Set[].send(@method).should.is_a?(String)
+    Set[nil, false, true].send(@method).should.is_a?(String)
+    Set[1, 2, 3].send(@method).should.is_a?(String)
+    Set["1", "2", "3"].send(@method).should.is_a?(String)
+    Set[:a, "b", Set[?c]].send(@method).should.is_a?(String)
+  end
+
+  ruby_version_is "4.0" do
+    it "does include the elements of the set" do
+      Set["1"].send(@method).should == 'Set["1"]'
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "does include the elements of the set" do
+      Set["1"].send(@method).should == '#<Set: {"1"}>'
+    end
+  end
+
+  it "puts spaces between the elements" do
+    Set["1", "2"].send(@method).should.include?('", "')
+  end
+
+  ruby_version_is "4.0" do
+    it "correctly handles cyclic-references" do
+      set1 = Set[]
+      set2 = Set[set1]
+      set1 << set2
+      set1.send(@method).should.is_a?(String)
+      set1.send(@method).should.include?("Set[...]")
+    end
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "correctly handles cyclic-references" do
+      set1 = Set[]
+      set2 = Set[set1]
+      set1 << set2
+      set1.send(@method).should.is_a?(String)
+      set1.send(@method).should.include?("#<Set: {...}>")
+    end
+  end
+end
diff --git a/spec/ruby/core/set/shared/intersection.rb b/spec/ruby/core/set/shared/intersection.rb
new file mode 100644
index 0000000000..978a4924ef
--- /dev/null
+++ b/spec/ruby/core/set/shared/intersection.rb
@@ -0,0 +1,15 @@
+describe :set_intersection, shared: true do
+  before :each do
+    @set = Set[:a, :b, :c]
+  end
+
+  it "returns a new Set containing only elements shared by self and the passed Enumerable" do
+    @set.send(@method, Set[:b, :c, :d, :e]).should == Set[:b, :c]
+    @set.send(@method, [:b, :c, :d]).should == Set[:b, :c]
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { @set.send(@method, 1) }.should.raise(ArgumentError)
+    -> { @set.send(@method, Object.new) }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/library/set/shared/length.rb b/spec/ruby/core/set/shared/length.rb
index a8fcee9f39..a8fcee9f39 100644
--- a/spec/ruby/library/set/shared/length.rb
+++ b/spec/ruby/core/set/shared/length.rb
diff --git a/spec/ruby/core/set/shared/select.rb b/spec/ruby/core/set/shared/select.rb
new file mode 100644
index 0000000000..0d4a53fffd
--- /dev/null
+++ b/spec/ruby/core/set/shared/select.rb
@@ -0,0 +1,41 @@
+require_relative '../../../spec_helper'
+
+describe :set_select_bang, shared: true do
+  before :each do
+    @set = Set["one", "two", "three"]
+  end
+
+  it "yields every element of self" do
+    ret = []
+    @set.send(@method) { |x| ret << x }
+    ret.sort.should == ["one", "two", "three"].sort
+  end
+
+  it "keeps every element from self for which the passed block returns true" do
+    @set.send(@method) { |x| x.size != 3 }
+    @set.size.should.eql?(1)
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+
+  it "returns self when self was modified" do
+    @set.send(@method) { false }.should.equal?(@set)
+  end
+
+  it "returns nil when self was not modified" do
+    @set.send(@method) { true }.should == nil
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.send(@method)
+    enum.should.instance_of?(Enumerator)
+
+    enum.each { |x| x.size != 3 }
+
+    @set.should_not.include?("one")
+    @set.should_not.include?("two")
+    @set.should.include?("three")
+  end
+end
diff --git a/spec/ruby/core/set/shared/union.rb b/spec/ruby/core/set/shared/union.rb
new file mode 100644
index 0000000000..dddf1716e5
--- /dev/null
+++ b/spec/ruby/core/set/shared/union.rb
@@ -0,0 +1,15 @@
+describe :set_union, shared: true do
+  before :each do
+    @set = Set[:a, :b, :c]
+  end
+
+  it "returns a new Set containing all elements of self and the passed Enumerable" do
+    @set.send(@method, Set[:b, :d, :e]).should == Set[:a, :b, :c, :d, :e]
+    @set.send(@method, [:b, :e]).should == Set[:a, :b, :c, :e]
+  end
+
+  it "raises an ArgumentError when passed a non-Enumerable" do
+    -> { @set.send(@method, 1) }.should.raise(ArgumentError)
+    -> { @set.send(@method, Object.new) }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/size_spec.rb b/spec/ruby/core/set/size_spec.rb
new file mode 100644
index 0000000000..4ae22c5f0a
--- /dev/null
+++ b/spec/ruby/core/set/size_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/length'
+
+describe "Set#size" do
+  it_behaves_like :set_length, :size
+end
diff --git a/spec/ruby/core/set/sortedset/sortedset_spec.rb b/spec/ruby/core/set/sortedset/sortedset_spec.rb
new file mode 100644
index 0000000000..c8f65f0851
--- /dev/null
+++ b/spec/ruby/core/set/sortedset/sortedset_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../../spec_helper'
+
+describe "SortedSet" do
+  ruby_version_is ""..."4.0" do
+    it "raises error including message that it has been extracted from the set stdlib" do
+      -> {
+        SortedSet
+      }.should.raise(RuntimeError) { |e|
+        e.message.should.include?("The `SortedSet` class has been extracted from the `set` library")
+      }
+    end
+  end
+end
diff --git a/spec/ruby/core/set/subset_spec.rb b/spec/ruby/core/set/subset_spec.rb
new file mode 100644
index 0000000000..81869d4993
--- /dev/null
+++ b/spec/ruby/core/set/subset_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+set_version = defined?(Set::VERSION) ? Set::VERSION : '1.0.0'
+
+describe "Set#subset?" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a Set that is equal to self or self is a subset of" do
+    @set.subset?(@set).should == true
+    Set[].subset?(Set[]).should == true
+
+    Set[].subset?(@set).should == true
+    Set[].subset?(Set[1, 2, 3]).should == true
+    Set[].subset?(Set["a", :b, ?c]).should == true
+
+    Set[1, 2, 3].subset?(@set).should == true
+    Set[1, 3].subset?(@set).should == true
+    Set[1, 2].subset?(@set).should == true
+    Set[1].subset?(@set).should == true
+
+    Set[5].subset?(@set).should == false
+    Set[1, 5].subset?(@set).should == false
+    Set[nil].subset?(@set).should == false
+    Set["test"].subset?(@set).should == false
+  end
+
+  it "raises an ArgumentError when passed a non-Set" do
+    -> { Set[].subset?([]) }.should.raise(ArgumentError)
+    -> { Set[].subset?(1) }.should.raise(ArgumentError)
+    -> { Set[].subset?("test") }.should.raise(ArgumentError)
+    -> { Set[].subset?(Object.new) }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/core/set/subtract_spec.rb b/spec/ruby/core/set/subtract_spec.rb
new file mode 100644
index 0000000000..ae4bc73d41
--- /dev/null
+++ b/spec/ruby/core/set/subtract_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../spec_helper'
+
+describe "Set#subtract" do
+  before :each do
+    @set = Set[:a, :b, :c]
+  end
+
+  it "deletes any elements contained in other and returns self" do
+    @set.subtract(Set[:b, :c]).should == @set
+    @set.should == Set[:a]
+  end
+
+  it "accepts any enumerable as other" do
+    @set.subtract([:c]).should == Set[:a, :b]
+  end
+end
diff --git a/spec/ruby/core/set/superset_spec.rb b/spec/ruby/core/set/superset_spec.rb
new file mode 100644
index 0000000000..7e7db2b179
--- /dev/null
+++ b/spec/ruby/core/set/superset_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
+
+describe "Set#superset?" do
+  before :each do
+    @set = Set[1, 2, 3, 4]
+  end
+
+  it "returns true if passed a Set that equals self or self is a proper superset of" do
+    @set.superset?(@set).should == true
+    Set[].superset?(Set[]).should == true
+
+    @set.superset?(Set[]).should == true
+    Set[1, 2, 3].superset?(Set[]).should == true
+    Set["a", :b, ?c].superset?(Set[]).should == true
+
+    @set.superset?(Set[1, 2, 3]).should == true
+    @set.superset?(Set[1, 3]).should == true
+    @set.superset?(Set[1, 2]).should == true
+    @set.superset?(Set[1]).should == true
+
+    @set.superset?(Set[5]).should == false
+    @set.superset?(Set[1, 5]).should == false
+    @set.superset?(Set[nil]).should == false
+    @set.superset?(Set["test"]).should == false
+  end
+
+  it "raises an ArgumentError when passed a non-Set" do
+    -> { Set[].superset?([]) }.should.raise(ArgumentError)
+    -> { Set[].superset?(1) }.should.raise(ArgumentError)
+    -> { Set[].superset?("test") }.should.raise(ArgumentError)
+    -> { Set[].superset?(Object.new) }.should.raise(ArgumentError)
+  end
+
+  ruby_version_is ""..."4.0" do
+    context "when comparing to a Set-like object" do
+      it "returns true if passed a Set-like object that self is a superset of" do
+        Set[1, 2, 3, 4].superset?(SetSpecs::SetLike.new([1, 2, 3])).should == true
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/set/to_a_spec.rb b/spec/ruby/core/set/to_a_spec.rb
new file mode 100644
index 0000000000..1e9800167a
--- /dev/null
+++ b/spec/ruby/core/set/to_a_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../spec_helper'
+
+describe "Set#to_a" do
+  it "returns an array containing elements of self" do
+    Set[1, 2, 3].to_a.sort.should == [1, 2, 3]
+  end
+end
diff --git a/spec/ruby/core/set/to_s_spec.rb b/spec/ruby/core/set/to_s_spec.rb
new file mode 100644
index 0000000000..55b8bfd9b2
--- /dev/null
+++ b/spec/ruby/core/set/to_s_spec.rb
@@ -0,0 +1,11 @@
+require_relative "../../spec_helper"
+require_relative 'shared/inspect'
+
+describe "Set#to_s" do
+  it_behaves_like :set_inspect, :to_s
+
+  it "is an alias of inspect" do
+    set = Set.new
+    set.method(:to_s).should == set.method(:inspect)
+  end
+end
diff --git a/spec/ruby/core/set/union_spec.rb b/spec/ruby/core/set/union_spec.rb
new file mode 100644
index 0000000000..3e77022d4b
--- /dev/null
+++ b/spec/ruby/core/set/union_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+require_relative 'shared/union'
+
+describe "Set#union" do
+  it_behaves_like :set_union, :union
+end
+
+describe "Set#|" do
+  it_behaves_like :set_union, :|
+end
diff --git a/spec/ruby/core/signal/signame_spec.rb b/spec/ruby/core/signal/signame_spec.rb
index b66de9fc85..82f040a6f9 100644
--- a/spec/ruby/core/signal/signame_spec.rb
+++ b/spec/ruby/core/signal/signame_spec.rb
@@ -9,8 +9,20 @@ describe "Signal.signame" do
     Signal.signame(-1).should == nil
   end
 
+  it "calls #to_int on an object to convert to an Integer" do
+    obj = mock('signal')
+    obj.should_receive(:to_int).and_return(0)
+    Signal.signame(obj).should == "EXIT"
+  end
+
   it "raises a TypeError when the passed argument can't be coerced to Integer" do
-    -> { Signal.signame("hello") }.should raise_error(TypeError)
+    -> { Signal.signame("hello") }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when the passed argument responds to #to_int but does not return an Integer" do
+    obj = mock('signal')
+    obj.should_receive(:to_int).and_return('not an int')
+    -> { Signal.signame(obj) }.should.raise(TypeError)
   end
 
   platform_is_not :windows do
diff --git a/spec/ruby/core/signal/trap_spec.rb b/spec/ruby/core/signal/trap_spec.rb
index 91ce1f1348..5d3105fee8 100644
--- a/spec/ruby/core/signal/trap_spec.rb
+++ b/spec/ruby/core/signal/trap_spec.rb
@@ -1,11 +1,12 @@
 require_relative '../../spec_helper'
 
-platform_is_not :windows do
-  describe "Signal.trap" do
+describe "Signal.trap" do
+  platform_is_not :windows do
     before :each do
       ScratchPad.clear
       @proc = -> {}
       @saved_trap = Signal.trap(:HUP, @proc)
+      @hup_number = Signal.list["HUP"]
     end
 
     after :each do
@@ -13,13 +14,14 @@ platform_is_not :windows do
     end
 
     it "returns the previous handler" do
-      Signal.trap(:HUP, @saved_trap).should equal(@proc)
+      Signal.trap(:HUP, @saved_trap).should.equal?(@proc)
     end
 
-    it "accepts a block in place of a proc/command argument" do
+    it "accepts a block" do
       done = false
 
-      Signal.trap(:HUP) do
+      Signal.trap(:HUP) do |signo|
+        signo.should == @hup_number
         ScratchPad.record :block_trap
         done = true
       end
@@ -30,6 +32,94 @@ platform_is_not :windows do
       ScratchPad.recorded.should == :block_trap
     end
 
+    it "accepts a proc" do
+      done = false
+
+      handler = -> signo {
+        signo.should == @hup_number
+        ScratchPad.record :proc_trap
+        done = true
+      }
+
+      Signal.trap(:HUP, handler)
+
+      Process.kill :HUP, Process.pid
+      Thread.pass until done
+
+      ScratchPad.recorded.should == :proc_trap
+    end
+
+    it "accepts a method" do
+      done = false
+
+      handler_class = Class.new
+      hup_number = @hup_number
+
+      handler_class.define_method :handler_method do |signo|
+        signo.should == hup_number
+        ScratchPad.record :method_trap
+        done = true
+      end
+
+      handler_method = handler_class.new.method(:handler_method)
+
+      Signal.trap(:HUP, handler_method)
+
+      Process.kill :HUP, Process.pid
+      Thread.pass until done
+
+      ScratchPad.recorded.should == :method_trap
+    end
+
+    it "accepts anything you can call" do
+      done = false
+
+      callable = Object.new
+      hup_number = @hup_number
+
+      callable.singleton_class.define_method :call do |signo|
+        signo.should == hup_number
+        ScratchPad.record :callable_trap
+        done = true
+      end
+
+      Signal.trap(:HUP, callable)
+
+      Process.kill :HUP, Process.pid
+      Thread.pass until done
+
+      ScratchPad.recorded.should == :callable_trap
+    end
+
+    it "raises an exception for a non-callable at the point of use" do
+      not_callable = Object.new
+      Signal.trap(:HUP, not_callable)
+      -> {
+        Process.kill :HUP, Process.pid
+        loop { Thread.pass }
+      }.should.raise(NoMethodError)
+    end
+
+    it "accepts a non-callable that becomes callable when used" do
+      done = false
+
+      late_callable = Object.new
+      hup_number = @hup_number
+
+      Signal.trap(:HUP, late_callable)
+
+      late_callable.singleton_class.define_method :call do |signo|
+        signo.should == hup_number
+        ScratchPad.record :late_callable_trap
+        done = true
+      end
+
+      Process.kill :HUP, Process.pid
+      Thread.pass until done
+
+      ScratchPad.recorded.should == :late_callable_trap
+    end
+
     it "is possible to create a new Thread when the handler runs" do
       done = false
 
@@ -44,17 +134,31 @@ platform_is_not :windows do
       Process.kill :HUP, Process.pid
       Thread.pass until done
 
-      ScratchPad.recorded.should be_true
+      ScratchPad.recorded.should == true
     end
 
     it "registers an handler doing nothing with :IGNORE" do
       Signal.trap :HUP, :IGNORE
+      Signal.trap(:HUP, @saved_trap).should == "IGNORE"
+    end
+
+    it "can register a new handler after :IGNORE" do
+      Signal.trap :HUP, :IGNORE
+
+      done = false
+      Signal.trap(:HUP) do
+        ScratchPad.record :block_trap
+        done = true
+      end
+
       Process.kill(:HUP, Process.pid).should == 1
+      Thread.pass until done
+      ScratchPad.recorded.should == :block_trap
     end
 
     it "ignores the signal when passed nil" do
       Signal.trap :HUP, nil
-      Signal.trap(:HUP, @saved_trap).should be_nil
+      Signal.trap(:HUP, @saved_trap).should == nil
     end
 
     it "accepts :DEFAULT in place of a proc" do
@@ -99,38 +203,75 @@ platform_is_not :windows do
 
     it "accepts long names as Strings" do
       Signal.trap "SIGHUP", @proc
-      Signal.trap("SIGHUP", @saved_trap).should equal(@proc)
+      Signal.trap("SIGHUP", @saved_trap).should.equal?(@proc)
     end
 
     it "accepts short names as Strings" do
       Signal.trap "HUP", @proc
-      Signal.trap("HUP", @saved_trap).should equal(@proc)
+      Signal.trap("HUP", @saved_trap).should.equal?(@proc)
     end
 
     it "accepts long names as Symbols" do
       Signal.trap :SIGHUP, @proc
-      Signal.trap(:SIGHUP, @saved_trap).should equal(@proc)
+      Signal.trap(:SIGHUP, @saved_trap).should.equal?(@proc)
     end
 
     it "accepts short names as Symbols" do
       Signal.trap :HUP, @proc
-      Signal.trap(:HUP, @saved_trap).should equal(@proc)
+      Signal.trap(:HUP, @saved_trap).should.equal?(@proc)
+    end
+
+    it "calls #to_str on an object to convert to a String" do
+      obj = mock("signal")
+      obj.should_receive(:to_str).exactly(2).times.and_return("HUP")
+      Signal.trap obj, @proc
+      Signal.trap(obj, @saved_trap).should.equal?(@proc)
+    end
+
+    it "accepts Integer values" do
+      hup = Signal.list["HUP"]
+      Signal.trap hup, @proc
+      Signal.trap(hup, @saved_trap).should.equal?(@proc)
+    end
+
+    it "does not call #to_int on an object to convert to an Integer" do
+      obj = mock("signal")
+      obj.should_not_receive(:to_int)
+      -> { Signal.trap obj, @proc }.should.raise(ArgumentError, /bad signal type/)
+    end
+
+    it "raises ArgumentError when passed unknown signal" do
+      -> { Signal.trap(300) { } }.should.raise(ArgumentError, "invalid signal number (300)")
+      -> { Signal.trap("USR10") { } }.should.raise(ArgumentError, /\Aunsupported signal [`']SIGUSR10'\z/)
+      -> { Signal.trap("SIGUSR10") { } }.should.raise(ArgumentError, /\Aunsupported signal [`']SIGUSR10'\z/)
+    end
+
+    it "raises ArgumentError when passed signal is not Integer, String or Symbol" do
+      -> { Signal.trap(nil) { } }.should.raise(ArgumentError, "bad signal type NilClass")
+      -> { Signal.trap(100.0) { } }.should.raise(ArgumentError, "bad signal type Float")
+      -> { Signal.trap(Rational(100)) { } }.should.raise(ArgumentError, "bad signal type Rational")
     end
-  end
 
-  describe "Signal.trap" do
     # See man 2 signal
     %w[KILL STOP].each do |signal|
       it "raises ArgumentError or Errno::EINVAL for SIG#{signal}" do
         -> {
-          trap(signal, -> {})
-        }.should raise_error(StandardError) { |e|
-          [ArgumentError, Errno::EINVAL].should include(e.class)
+          Signal.trap(signal, -> {})
+        }.should.raise(StandardError) { |e|
+          [ArgumentError, Errno::EINVAL].should.include?(e.class)
           e.message.should =~ /Invalid argument|Signal already used by VM or OS/
         }
       end
     end
 
+    %w[SEGV BUS ILL FPE VTALRM].each do |signal|
+      it "raises ArgumentError for SIG#{signal} which is reserved by Ruby" do
+        -> {
+          Signal.trap(signal, -> {})
+        }.should.raise(ArgumentError, "can't trap reserved signal: SIG#{signal}")
+      end
+    end
+
     it "allows to register a handler for all known signals, except reserved signals for which it raises ArgumentError" do
       out = ruby_exe(fixture(__FILE__, "trap_all.rb"), args: "2>&1")
       out.should == "OK\n"
@@ -138,7 +279,7 @@ platform_is_not :windows do
     end
 
     it "returns 'DEFAULT' for the initial SIGINT handler" do
-      ruby_exe('print trap(:INT) { abort }').should == 'DEFAULT'
+      ruby_exe("print Signal.trap(:INT) { abort }").should == 'DEFAULT'
     end
 
     it "returns SYSTEM_DEFAULT if passed DEFAULT and no handler was ever set" do
@@ -152,31 +293,28 @@ platform_is_not :windows do
         r.close
         loop { w.write("a"*1024) }
       RUBY
-      out = ruby_exe(code)
+      out = ruby_exe(code, exit_status: :SIGPIPE)
       status = $?
       out.should == "nil\n"
-      status.signaled?.should == true
-      status.termsig.should be_kind_of(Integer)
-      Signal.signame(status.termsig).should == "PIPE"
+      status.should.signaled?
     end
   end
-end
 
-describe "Signal.trap" do
   describe "the special EXIT signal code" do
     it "accepts the EXIT code" do
-      code = "trap(:EXIT, proc { print 1 })"
+      code = "Signal.trap(:EXIT, proc { print 1 })"
       ruby_exe(code).should == "1"
     end
 
     it "runs the proc before at_exit handlers" do
-      code = "at_exit {print 1}; trap(:EXIT, proc {print 2}); at_exit {print 3}"
+      code = "at_exit {print 1}; Signal.trap(:EXIT, proc {print 2}); at_exit {print 3}"
       ruby_exe(code).should == "231"
     end
 
     it "can unset the handler" do
-      code = "trap(:EXIT, proc { print 1 }); trap(:EXIT, 'DEFAULT')"
+      code = "Signal.trap(:EXIT, proc { print 1 }); Signal.trap(:EXIT, 'DEFAULT')"
       ruby_exe(code).should == ""
     end
   end
+
 end
diff --git a/spec/ruby/core/sizedqueue/append_spec.rb b/spec/ruby/core/sizedqueue/append_spec.rb
index ca79068930..c52baa3802 100644
--- a/spec/ruby/core/sizedqueue/append_spec.rb
+++ b/spec/ruby/core/sizedqueue/append_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/enque'
 require_relative '../../shared/sizedqueue/enque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#<<" do
   it_behaves_like :queue_enq, :<<, -> { SizedQueue.new(10) }
@@ -9,3 +10,7 @@ end
 describe "SizedQueue#<<" do
   it_behaves_like :sizedqueue_enq, :<<, -> n { SizedQueue.new(n) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(1); q.send(:<<, 1, timeout: v) }
+end
diff --git a/spec/ruby/core/sizedqueue/deq_spec.rb b/spec/ruby/core/sizedqueue/deq_spec.rb
index 5e1bd9f746..2aeb52f8a6 100644
--- a/spec/ruby/core/sizedqueue/deq_spec.rb
+++ b/spec/ruby/core/sizedqueue/deq_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#deq" do
   it_behaves_like :queue_deq, :deq, -> { SizedQueue.new(10) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(10); q.push(1); q.deq(timeout: v) }
+end
diff --git a/spec/ruby/core/sizedqueue/enq_spec.rb b/spec/ruby/core/sizedqueue/enq_spec.rb
index 3821afac95..b955909475 100644
--- a/spec/ruby/core/sizedqueue/enq_spec.rb
+++ b/spec/ruby/core/sizedqueue/enq_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/enque'
 require_relative '../../shared/sizedqueue/enque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#enq" do
   it_behaves_like :queue_enq, :enq, -> { SizedQueue.new(10) }
@@ -9,3 +10,7 @@ end
 describe "SizedQueue#enq" do
   it_behaves_like :sizedqueue_enq, :enq, -> n { SizedQueue.new(n) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(1); q.enq(1, timeout: v) }
+end
diff --git a/spec/ruby/core/sizedqueue/freeze_spec.rb b/spec/ruby/core/sizedqueue/freeze_spec.rb
new file mode 100644
index 0000000000..98f01cae2f
--- /dev/null
+++ b/spec/ruby/core/sizedqueue/freeze_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/queue/freeze'
+
+describe "SizedQueue#freeze" do
+  it_behaves_like :queue_freeze, :freeze, -> { SizedQueue.new(1) }
+end
diff --git a/spec/ruby/core/sizedqueue/pop_spec.rb b/spec/ruby/core/sizedqueue/pop_spec.rb
index a0cf6f509c..6338ddbaa0 100644
--- a/spec/ruby/core/sizedqueue/pop_spec.rb
+++ b/spec/ruby/core/sizedqueue/pop_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#pop" do
   it_behaves_like :queue_deq, :pop, -> { SizedQueue.new(10) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(10); q.push(1); q.pop(timeout: v) }
+end
diff --git a/spec/ruby/core/sizedqueue/push_spec.rb b/spec/ruby/core/sizedqueue/push_spec.rb
index bba9be9e3f..9eaa6beca0 100644
--- a/spec/ruby/core/sizedqueue/push_spec.rb
+++ b/spec/ruby/core/sizedqueue/push_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/enque'
 require_relative '../../shared/sizedqueue/enque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#push" do
   it_behaves_like :queue_enq, :push, -> { SizedQueue.new(10) }
@@ -9,3 +10,7 @@ end
 describe "SizedQueue#push" do
   it_behaves_like :sizedqueue_enq, :push, -> n { SizedQueue.new(n) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(1); q.push(1, timeout: v) }
+end
diff --git a/spec/ruby/core/sizedqueue/shift_spec.rb b/spec/ruby/core/sizedqueue/shift_spec.rb
index 5138e68258..52974c1d99 100644
--- a/spec/ruby/core/sizedqueue/shift_spec.rb
+++ b/spec/ruby/core/sizedqueue/shift_spec.rb
@@ -1,6 +1,11 @@
 require_relative '../../spec_helper'
 require_relative '../../shared/queue/deque'
+require_relative '../../shared/types/rb_num2dbl_fails'
 
 describe "SizedQueue#shift" do
   it_behaves_like :queue_deq, :shift, -> { SizedQueue.new(10) }
 end
+
+describe "SizedQueue operations with timeout" do
+  it_behaves_like :rb_num2dbl_fails, nil, -> v { q = SizedQueue.new(10); q.push(1); q.shift(timeout: v) }
+end
diff --git a/spec/ruby/core/string/allocate_spec.rb b/spec/ruby/core/string/allocate_spec.rb
index 5b36b4fd05..00dadaf076 100644
--- a/spec/ruby/core/string/allocate_spec.rb
+++ b/spec/ruby/core/string/allocate_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "String.allocate" do
   it "returns an instance of String" do
     str = String.allocate
-    str.should be_an_instance_of(String)
+    str.should.instance_of?(String)
   end
 
   it "returns a fully-formed String" do
@@ -14,6 +14,6 @@ describe "String.allocate" do
   end
 
   it "returns a binary String" do
-    String.new.encoding.should == Encoding::BINARY
+    String.allocate.encoding.should == Encoding::BINARY
   end
 end
diff --git a/spec/ruby/core/string/append_as_bytes_spec.rb b/spec/ruby/core/string/append_as_bytes_spec.rb
new file mode 100644
index 0000000000..feead64615
--- /dev/null
+++ b/spec/ruby/core/string/append_as_bytes_spec.rb
@@ -0,0 +1,60 @@
+require_relative '../../spec_helper'
+
+describe "String#append_bytes" do
+  ruby_version_is "3.4" do
+    it "doesn't allow to mutate frozen strings" do
+      str = "hello".freeze
+      -> { str.append_as_bytes("\xE2\x82") }.should.raise(FrozenError)
+    end
+
+    it "allows creating broken strings in UTF8" do
+      str = +"hello"
+      str.append_as_bytes("\xE2\x82")
+      str.valid_encoding?.should == false
+
+      str.append_as_bytes("\xAC")
+      str.valid_encoding?.should == true
+    end
+
+    it "allows creating broken strings in UTF_32" do
+      str = "abc".encode(Encoding::UTF_32LE)
+      str.append_as_bytes("def")
+      str.encoding.should == Encoding::UTF_32LE
+      str.valid_encoding?.should == false
+    end
+
+    it "never changes the receiver encoding" do
+      str = "".b
+      str.append_as_bytes("€")
+      str.encoding.should == Encoding::BINARY
+    end
+
+    it "accepts variadic String or Integer arguments" do
+      str = "hello".b
+      str.append_as_bytes("\xE2\x82", 12, 43, "\xAC")
+      str.encoding.should == Encoding::BINARY
+      str.should == "hello\xE2\x82\f+\xAC".b
+    end
+
+    it "truncates integers to the least significant byte" do
+      str = +""
+      str.append_as_bytes(0x131, 0x232, 0x333, bignum_value, bignum_value(1))
+      str.bytes.should == [0x31, 0x32, 0x33, 0, 1]
+    end
+
+    it "wraps negative integers" do
+      str = "".b
+      str.append_as_bytes(-1, -bignum_value, -bignum_value(1))
+      str.bytes.should == [0xFF, 0, 0xFF]
+    end
+
+    it "only accepts strings or integers, and doesn't attempt to cast with #to_str or #to_int" do
+      to_str = mock("to_str")
+      to_str.should_not_receive(:to_str)
+      to_str.should_not_receive(:to_int)
+
+      str = +"hello"
+      -> { str.append_as_bytes(to_str) }.should.raise(TypeError, "wrong argument type MockObject (expected String or Integer)")
+    end
+  end
+end
diff --git a/spec/ruby/core/string/append_spec.rb b/spec/ruby/core/string/append_spec.rb
index 1e1667f617..e0f71b7c97 100644
--- a/spec/ruby/core/string/append_spec.rb
+++ b/spec/ruby/core/string/append_spec.rb
@@ -5,4 +5,10 @@ require_relative 'shared/concat'
 describe "String#<<" do
   it_behaves_like :string_concat, :<<
   it_behaves_like :string_concat_encoding, :<<
+  it_behaves_like :string_concat_type_coercion, :<<
+
+  it "raises an ArgumentError when given the incorrect number of arguments" do
+    -> { "hello".send(:<<) }.should.raise(ArgumentError)
+    -> { "hello".send(:<<, "one", "two") }.should.raise(ArgumentError)
+  end
 end
diff --git a/spec/ruby/core/string/ascii_only_spec.rb b/spec/ruby/core/string/ascii_only_spec.rb
index c7e02fd874..9af663beb8 100644
--- a/spec/ruby/core/string/ascii_only_spec.rb
+++ b/spec/ruby/core/string/ascii_only_spec.rb
@@ -7,18 +7,18 @@ describe "String#ascii_only?" do
     it "returns true if the encoding is UTF-8" do
       [ ["hello",                         true],
         ["hello".encode('UTF-8'),         true],
-        ["hello".force_encoding('UTF-8'), true],
+        ["hello".dup.force_encoding('UTF-8'), true],
       ].should be_computed_by(:ascii_only?)
     end
 
     it "returns true if the encoding is US-ASCII" do
-      "hello".force_encoding(Encoding::US_ASCII).ascii_only?.should be_true
-      "hello".encode(Encoding::US_ASCII).ascii_only?.should be_true
+      "hello".dup.force_encoding(Encoding::US_ASCII).ascii_only?.should == true
+      "hello".encode(Encoding::US_ASCII).ascii_only?.should == true
     end
 
     it "returns true for all single-character UTF-8 Strings" do
       0.upto(127) do |n|
-        n.chr.ascii_only?.should be_true
+        n.chr.ascii_only?.should == true
       end
     end
   end
@@ -27,57 +27,56 @@ describe "String#ascii_only?" do
     it "returns false if the encoding is BINARY" do
       chr = 128.chr
       chr.encoding.should == Encoding::BINARY
-      chr.ascii_only?.should be_false
+      chr.ascii_only?.should == false
     end
 
     it "returns false if the String contains any non-ASCII characters" do
       [ ["\u{6666}",                          false],
         ["hello, \u{6666}",                   false],
         ["\u{6666}".encode('UTF-8'),          false],
-        ["\u{6666}".force_encoding('UTF-8'),  false],
+        ["\u{6666}".dup.force_encoding('UTF-8'),  false],
       ].should be_computed_by(:ascii_only?)
     end
 
     it "returns false if the encoding is US-ASCII" do
-      [ ["\u{6666}".force_encoding(Encoding::US_ASCII),         false],
-        ["hello, \u{6666}".force_encoding(Encoding::US_ASCII),  false],
+      [ ["\u{6666}".dup.force_encoding(Encoding::US_ASCII),         false],
+        ["hello, \u{6666}".dup.force_encoding(Encoding::US_ASCII),  false],
       ].should be_computed_by(:ascii_only?)
     end
   end
 
   it "returns true for the empty String with an ASCII-compatible encoding" do
-    "".ascii_only?.should be_true
-    "".encode('UTF-8').ascii_only?.should be_true
+    "".ascii_only?.should == true
+    "".encode('UTF-8').ascii_only?.should == true
   end
 
   it "returns false for the empty String with a non-ASCII-compatible encoding" do
-    "".force_encoding('UTF-16LE').ascii_only?.should be_false
-    "".encode('UTF-16BE').ascii_only?.should be_false
+    "".dup.force_encoding('UTF-16LE').ascii_only?.should == false
+    "".encode('UTF-16BE').ascii_only?.should == false
   end
 
   it "returns false for a non-empty String with non-ASCII-compatible encoding" do
-    "\x78\x00".force_encoding("UTF-16LE").ascii_only?.should be_false
+    "\x78\x00".dup.force_encoding("UTF-16LE").ascii_only?.should == false
   end
 
   it "returns false when interpolating non ascii strings" do
-    base = "EU currency is"
-    base.force_encoding(Encoding::US_ASCII)
+    base = "EU currency is".dup.force_encoding(Encoding::US_ASCII)
     euro = "\u20AC"
     interp = "#{base} #{euro}"
-    euro.ascii_only?.should be_false
-    base.ascii_only?.should be_true
-    interp.ascii_only?.should be_false
+    euro.ascii_only?.should == false
+    base.ascii_only?.should == true
+    interp.ascii_only?.should == false
   end
 
   it "returns false after appending non ASCII characters to an empty String" do
-    ("" << "λ").ascii_only?.should be_false
+    ("".dup << "λ").ascii_only?.should == false
   end
 
   it "returns false when concatenating an ASCII and non-ASCII String" do
-    "".concat("λ").ascii_only?.should be_false
+    "".dup.concat("λ").ascii_only?.should == false
   end
 
   it "returns false when replacing an ASCII String with a non-ASCII String" do
-    "".replace("λ").ascii_only?.should be_false
+    "".dup.replace("λ").ascii_only?.should == false
   end
 end
diff --git a/spec/ruby/core/string/b_spec.rb b/spec/ruby/core/string/b_spec.rb
index b43cb5393a..d181447709 100644
--- a/spec/ruby/core/string/b_spec.rb
+++ b/spec/ruby/core/string/b_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#b" do
@@ -9,14 +10,7 @@ describe "String#b" do
 
   it "returns new string without modifying self" do
     str = "こんちには"
-    str.b.should_not equal(str)
+    str.b.should_not.equal?(str)
     str.should == "こんちには"
   end
-
-  it "copies own tainted/untrusted status to the returning value" do
-    utf_8 = "こんちには".taint.untrust
-    ret = utf_8.b
-    ret.tainted?.should be_true
-    ret.untrusted?.should be_true
-  end
 end
diff --git a/spec/ruby/core/string/byteindex_spec.rb b/spec/ruby/core/string/byteindex_spec.rb
new file mode 100644
index 0000000000..f4c6408790
--- /dev/null
+++ b/spec/ruby/core/string/byteindex_spec.rb
@@ -0,0 +1,298 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'shared/byte_index_common.rb'
+
+describe "String#byteindex" do
+  it "calls #to_str to convert the first argument" do
+    char = mock("string index char")
+    char.should_receive(:to_str).and_return("b")
+    "abc".byteindex(char).should == 1
+  end
+
+  it "calls #to_int to convert the second argument" do
+    offset = mock("string index offset")
+    offset.should_receive(:to_int).and_return(1)
+    "abc".byteindex("c", offset).should == 2
+  end
+
+  it "does not raise IndexError when byte offset is correct or on string boundary" do
+    "わ".byteindex("").should == 0
+    "わ".byteindex("", 0).should == 0
+    "わ".byteindex("", 3).should == 3
+  end
+
+  it_behaves_like :byte_index_common, :byteindex
+end
+
+describe "String#byteindex with String" do
+  it "behaves the same as String#byteindex(char) for one-character strings" do
+    "blablabla hello cruel world...!".split("").uniq.each do |str|
+      chr = str[0]
+      str.byteindex(str).should == str.byteindex(chr)
+
+      0.upto(str.size + 1) do |start|
+        str.byteindex(str, start).should == str.byteindex(chr, start)
+      end
+
+      (-str.size - 1).upto(-1) do |start|
+        str.byteindex(str, start).should == str.byteindex(chr, start)
+      end
+    end
+  end
+
+  it "returns the byteindex of the first occurrence of the given substring" do
+    "blablabla".byteindex("").should == 0
+    "blablabla".byteindex("b").should == 0
+    "blablabla".byteindex("bla").should == 0
+    "blablabla".byteindex("blabla").should == 0
+    "blablabla".byteindex("blablabla").should == 0
+
+    "blablabla".byteindex("l").should == 1
+    "blablabla".byteindex("la").should == 1
+    "blablabla".byteindex("labla").should == 1
+    "blablabla".byteindex("lablabla").should == 1
+
+    "blablabla".byteindex("a").should == 2
+    "blablabla".byteindex("abla").should == 2
+    "blablabla".byteindex("ablabla").should == 2
+  end
+
+  it "treats the offset as a byteindex" do
+    "aaaaa".byteindex("a", 0).should == 0
+    "aaaaa".byteindex("a", 2).should == 2
+    "aaaaa".byteindex("a", 4).should == 4
+  end
+
+  it "ignores string subclasses" do
+    "blablabla".byteindex(StringSpecs::MyString.new("bla")).should == 0
+    StringSpecs::MyString.new("blablabla").byteindex("bla").should == 0
+    StringSpecs::MyString.new("blablabla").byteindex(StringSpecs::MyString.new("bla")).should == 0
+  end
+
+  it "starts the search at the given offset" do
+    "blablabla".byteindex("bl", 0).should == 0
+    "blablabla".byteindex("bl", 1).should == 3
+    "blablabla".byteindex("bl", 2).should == 3
+    "blablabla".byteindex("bl", 3).should == 3
+
+    "blablabla".byteindex("bla", 0).should == 0
+    "blablabla".byteindex("bla", 1).should == 3
+    "blablabla".byteindex("bla", 2).should == 3
+    "blablabla".byteindex("bla", 3).should == 3
+
+    "blablabla".byteindex("blab", 0).should == 0
+    "blablabla".byteindex("blab", 1).should == 3
+    "blablabla".byteindex("blab", 2).should == 3
+    "blablabla".byteindex("blab", 3).should == 3
+
+    "blablabla".byteindex("la", 1).should == 1
+    "blablabla".byteindex("la", 2).should == 4
+    "blablabla".byteindex("la", 3).should == 4
+    "blablabla".byteindex("la", 4).should == 4
+
+    "blablabla".byteindex("lab", 1).should == 1
+    "blablabla".byteindex("lab", 2).should == 4
+    "blablabla".byteindex("lab", 3).should == 4
+    "blablabla".byteindex("lab", 4).should == 4
+
+    "blablabla".byteindex("ab", 2).should == 2
+    "blablabla".byteindex("ab", 3).should == 5
+    "blablabla".byteindex("ab", 4).should == 5
+    "blablabla".byteindex("ab", 5).should == 5
+
+    "blablabla".byteindex("", 0).should == 0
+    "blablabla".byteindex("", 1).should == 1
+    "blablabla".byteindex("", 2).should == 2
+    "blablabla".byteindex("", 7).should == 7
+    "blablabla".byteindex("", 8).should == 8
+    "blablabla".byteindex("", 9).should == 9
+  end
+
+  it "starts the search at offset + self.length if offset is negative" do
+    str = "blablabla"
+
+    ["bl", "bla", "blab", "la", "lab", "ab", ""].each do |needle|
+      (-str.length .. -1).each do |offset|
+        str.byteindex(needle, offset).should ==
+        str.byteindex(needle, offset + str.length)
+      end
+    end
+  end
+
+  it "returns nil if the substring isn't found" do
+    "blablabla".byteindex("B").should == nil
+    "blablabla".byteindex("z").should == nil
+    "blablabla".byteindex("BLA").should == nil
+    "blablabla".byteindex("blablablabla").should == nil
+    "blablabla".byteindex("", 10).should == nil
+
+    "hello".byteindex("he", 1).should == nil
+    "hello".byteindex("he", 2).should == nil
+    "I’ve got a multibyte character.\n".byteindex("\n\n").should == nil
+  end
+
+  it "returns the character byteindex of a multibyte character" do
+    "ありがとう".byteindex("が").should == 6
+  end
+
+  it "returns the character byteindex after offset" do
+    "われわれ".byteindex("わ", 3).should == 6
+    "ありがとうありがとう".byteindex("が", 9).should == 21
+  end
+
+  it "returns the character byteindex after a partial first match" do
+    "</</h".byteindex("</h").should == 2
+  end
+
+  it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
+    char = "れ".encode Encoding::EUC_JP
+    -> do
+      "あれ".byteindex(char)
+    end.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "handles a substring in a superset encoding" do
+    'abc'.dup.force_encoding(Encoding::US_ASCII).byteindex('é').should == nil
+  end
+
+  it "handles a substring in a subset encoding" do
+    'été'.byteindex('t'.dup.force_encoding(Encoding::US_ASCII)).should == 2
+  end
+end
+
+describe "String#byteindex with Regexp" do
+  it "behaves the same as String#byteindex(string) for escaped string regexps" do
+    ["blablabla", "hello cruel world...!"].each do |str|
+      ["", "b", "bla", "lab", "o c", "d."].each do |needle|
+        regexp = Regexp.new(Regexp.escape(needle))
+        str.byteindex(regexp).should == str.byteindex(needle)
+
+        0.upto(str.size + 1) do |start|
+          str.byteindex(regexp, start).should == str.byteindex(needle, start)
+        end
+
+        (-str.size - 1).upto(-1) do |start|
+          str.byteindex(regexp, start).should == str.byteindex(needle, start)
+        end
+      end
+    end
+  end
+
+  it "returns the byteindex of the first match of regexp" do
+    "blablabla".byteindex(/bla/).should == 0
+    "blablabla".byteindex(/BLA/i).should == 0
+
+    "blablabla".byteindex(/.{0}/).should == 0
+    "blablabla".byteindex(/.{6}/).should == 0
+    "blablabla".byteindex(/.{9}/).should == 0
+
+    "blablabla".byteindex(/.*/).should == 0
+    "blablabla".byteindex(/.+/).should == 0
+
+    "blablabla".byteindex(/lab|b/).should == 0
+
+    not_supported_on :opal do
+      "blablabla".byteindex(/\A/).should == 0
+      "blablabla".byteindex(/\Z/).should == 9
+      "blablabla".byteindex(/\z/).should == 9
+      "blablabla\n".byteindex(/\Z/).should == 9
+      "blablabla\n".byteindex(/\z/).should == 10
+    end
+
+    "blablabla".byteindex(/^/).should == 0
+    "\nblablabla".byteindex(/^/).should == 0
+    "b\nablabla".byteindex(/$/).should == 1
+    "bl\nablabla".byteindex(/$/).should == 2
+
+    "blablabla".byteindex(/.l./).should == 0
+  end
+
+  it "starts the search at the given offset" do
+    "blablabla".byteindex(/.{0}/, 5).should == 5
+    "blablabla".byteindex(/.{1}/, 5).should == 5
+    "blablabla".byteindex(/.{2}/, 5).should == 5
+    "blablabla".byteindex(/.{3}/, 5).should == 5
+    "blablabla".byteindex(/.{4}/, 5).should == 5
+
+    "blablabla".byteindex(/.{0}/, 3).should == 3
+    "blablabla".byteindex(/.{1}/, 3).should == 3
+    "blablabla".byteindex(/.{2}/, 3).should == 3
+    "blablabla".byteindex(/.{5}/, 3).should == 3
+    "blablabla".byteindex(/.{6}/, 3).should == 3
+
+    "blablabla".byteindex(/.l./, 0).should == 0
+    "blablabla".byteindex(/.l./, 1).should == 3
+    "blablabla".byteindex(/.l./, 2).should == 3
+    "blablabla".byteindex(/.l./, 3).should == 3
+
+    "xblaxbla".byteindex(/x./, 0).should == 0
+    "xblaxbla".byteindex(/x./, 1).should == 4
+    "xblaxbla".byteindex(/x./, 2).should == 4
+
+    not_supported_on :opal do
+      "blablabla\n".byteindex(/\Z/, 9).should == 9
+    end
+  end
+
+  it "starts the search at offset + self.length if offset is negative" do
+    str = "blablabla"
+
+    ["bl", "bla", "blab", "la", "lab", "ab", ""].each do |needle|
+      (-str.length .. -1).each do |offset|
+        str.byteindex(needle, offset).should ==
+        str.byteindex(needle, offset + str.length)
+      end
+    end
+  end
+
+  it "returns nil if the substring isn't found" do
+    "blablabla".byteindex(/BLA/).should == nil
+
+    "blablabla".byteindex(/.{10}/).should == nil
+    "blaxbla".byteindex(/.x/, 3).should == nil
+    "blaxbla".byteindex(/..x/, 2).should == nil
+  end
+
+  it "returns nil if the Regexp matches the empty string and the offset is out of range" do
+    "ruby".byteindex(//, 12).should == nil
+  end
+
+  it "supports \\G which matches at the given start offset" do
+    "helloYOU.".byteindex(/\GYOU/, 5).should == 5
+    "helloYOU.".byteindex(/\GYOU/).should == nil
+
+    re = /\G.+YOU/
+    # The # marks where \G will match.
+    [
+      ["#hi!YOUall.", 0],
+      ["h#i!YOUall.", 1],
+      ["hi#!YOUall.", 2],
+      ["hi!#YOUall.", nil]
+    ].each do |spec|
+
+      start = spec[0].byteindex("#")
+      str = spec[0].delete("#")
+
+      str.byteindex(re, start).should == spec[1]
+    end
+  end
+
+  it "converts start_offset to an integer via to_int" do
+    obj = mock('1')
+    obj.should_receive(:to_int).and_return(1)
+    "RWOARW".byteindex(/R./, obj).should == 4
+  end
+
+  it "returns the character byteindex of a multibyte character" do
+    "ありがとう".byteindex(/が/).should == 6
+  end
+
+  it "returns the character byteindex after offset" do
+    "われわれ".byteindex(/わ/, 3).should == 6
+  end
+
+  it "treats the offset as a byteindex" do
+    "われわわれ".byteindex(/わ/, 6).should == 6
+  end
+end
diff --git a/spec/ruby/core/string/byterindex_spec.rb b/spec/ruby/core/string/byterindex_spec.rb
new file mode 100644
index 0000000000..569820463d
--- /dev/null
+++ b/spec/ruby/core/string/byterindex_spec.rb
@@ -0,0 +1,353 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'shared/byte_index_common.rb'
+
+describe "String#byterindex with object" do
+  it "tries to convert obj to a string via to_str" do
+    obj = mock('lo')
+    def obj.to_str() "lo" end
+    "hello".byterindex(obj).should == "hello".byterindex("lo")
+
+    obj = mock('o')
+    def obj.respond_to?(arg, *) true end
+    def obj.method_missing(*args) "o" end
+    "hello".byterindex(obj).should == "hello".byterindex("o")
+  end
+
+  it "calls #to_int to convert the second argument" do
+    offset = mock("string index offset")
+    offset.should_receive(:to_int).and_return(3)
+    "abc".byterindex("c", offset).should == 2
+  end
+
+  it "does not raise IndexError when byte offset is correct or on string boundary" do
+    "わ".byterindex("", 0).should == 0
+    "わ".byterindex("", 3).should == 3
+    "わ".byterindex("").should == 3
+  end
+
+  it_behaves_like :byte_index_common, :byterindex
+end
+
+describe "String#byterindex with String" do
+  it "behaves the same as String#byterindex(char) for one-character strings" do
+    "blablabla hello cruel world...!".split("").uniq.each do |str|
+      chr = str[0]
+      str.byterindex(str).should == str.byterindex(chr)
+
+      0.upto(str.size + 1) do |start|
+        str.byterindex(str, start).should == str.byterindex(chr, start)
+      end
+
+      (-str.size - 1).upto(-1) do |start|
+        str.byterindex(str, start).should == str.byterindex(chr, start)
+      end
+    end
+  end
+
+  it "behaves the same as String#byterindex(?char) for one-character strings" do
+    "blablabla hello cruel world...!".split("").uniq.each do |str|
+      chr = str[0] =~ / / ? str[0] : eval("?#{str[0]}")
+      str.byterindex(str).should == str.byterindex(chr)
+
+      0.upto(str.size + 1) do |start|
+        str.byterindex(str, start).should == str.byterindex(chr, start)
+      end
+
+      (-str.size - 1).upto(-1) do |start|
+        str.byterindex(str, start).should == str.byterindex(chr, start)
+      end
+    end
+  end
+
+  it "returns the index of the last occurrence of the given substring" do
+    "blablabla".byterindex("").should == 9
+    "blablabla".byterindex("a").should == 8
+    "blablabla".byterindex("la").should == 7
+    "blablabla".byterindex("bla").should == 6
+    "blablabla".byterindex("abla").should == 5
+    "blablabla".byterindex("labla").should == 4
+    "blablabla".byterindex("blabla").should == 3
+    "blablabla".byterindex("ablabla").should == 2
+    "blablabla".byterindex("lablabla").should == 1
+    "blablabla".byterindex("blablabla").should == 0
+
+    "blablabla".byterindex("l").should == 7
+    "blablabla".byterindex("bl").should == 6
+    "blablabla".byterindex("abl").should == 5
+    "blablabla".byterindex("labl").should == 4
+    "blablabla".byterindex("blabl").should == 3
+    "blablabla".byterindex("ablabl").should == 2
+    "blablabla".byterindex("lablabl").should == 1
+    "blablabla".byterindex("blablabl").should == 0
+
+    "blablabla".byterindex("b").should == 6
+    "blablabla".byterindex("ab").should == 5
+    "blablabla".byterindex("lab").should == 4
+    "blablabla".byterindex("blab").should == 3
+    "blablabla".byterindex("ablab").should == 2
+    "blablabla".byterindex("lablab").should == 1
+    "blablabla".byterindex("blablab").should == 0
+  end
+
+  it "ignores string subclasses" do
+    "blablabla".byterindex(StringSpecs::MyString.new("bla")).should == 6
+    StringSpecs::MyString.new("blablabla").byterindex("bla").should == 6
+    StringSpecs::MyString.new("blablabla").byterindex(StringSpecs::MyString.new("bla")).should == 6
+  end
+
+  it "starts the search at the given offset" do
+    "blablabla".byterindex("bl", 0).should == 0
+    "blablabla".byterindex("bl", 1).should == 0
+    "blablabla".byterindex("bl", 2).should == 0
+    "blablabla".byterindex("bl", 3).should == 3
+
+    "blablabla".byterindex("bla", 0).should == 0
+    "blablabla".byterindex("bla", 1).should == 0
+    "blablabla".byterindex("bla", 2).should == 0
+    "blablabla".byterindex("bla", 3).should == 3
+
+    "blablabla".byterindex("blab", 0).should == 0
+    "blablabla".byterindex("blab", 1).should == 0
+    "blablabla".byterindex("blab", 2).should == 0
+    "blablabla".byterindex("blab", 3).should == 3
+    "blablabla".byterindex("blab", 6).should == 3
+    "blablablax".byterindex("blab", 6).should == 3
+
+    "blablabla".byterindex("la", 1).should == 1
+    "blablabla".byterindex("la", 2).should == 1
+    "blablabla".byterindex("la", 3).should == 1
+    "blablabla".byterindex("la", 4).should == 4
+
+    "blablabla".byterindex("lab", 1).should == 1
+    "blablabla".byterindex("lab", 2).should == 1
+    "blablabla".byterindex("lab", 3).should == 1
+    "blablabla".byterindex("lab", 4).should == 4
+
+    "blablabla".byterindex("ab", 2).should == 2
+    "blablabla".byterindex("ab", 3).should == 2
+    "blablabla".byterindex("ab", 4).should == 2
+    "blablabla".byterindex("ab", 5).should == 5
+
+    "blablabla".byterindex("", 0).should == 0
+    "blablabla".byterindex("", 1).should == 1
+    "blablabla".byterindex("", 2).should == 2
+    "blablabla".byterindex("", 7).should == 7
+    "blablabla".byterindex("", 8).should == 8
+    "blablabla".byterindex("", 9).should == 9
+    "blablabla".byterindex("", 10).should == 9
+  end
+
+  it "starts the search at offset + self.length if offset is negative" do
+    str = "blablabla"
+
+    ["bl", "bla", "blab", "la", "lab", "ab", ""].each do |needle|
+      (-str.length .. -1).each do |offset|
+        str.byterindex(needle, offset).should ==
+        str.byterindex(needle, offset + str.length)
+      end
+    end
+  end
+
+  it "returns nil if the substring isn't found" do
+    "blablabla".byterindex("B").should == nil
+    "blablabla".byterindex("z").should == nil
+    "blablabla".byterindex("BLA").should == nil
+    "blablabla".byterindex("blablablabla").should == nil
+
+    "hello".byterindex("lo", 0).should == nil
+    "hello".byterindex("lo", 1).should == nil
+    "hello".byterindex("lo", 2).should == nil
+
+    "hello".byterindex("llo", 0).should == nil
+    "hello".byterindex("llo", 1).should == nil
+
+    "hello".byterindex("el", 0).should == nil
+    "hello".byterindex("ello", 0).should == nil
+
+    "hello".byterindex("", -6).should == nil
+    "hello".byterindex("", -7).should == nil
+
+    "hello".byterindex("h", -6).should == nil
+  end
+
+  it "tries to convert start_offset to an integer via to_int" do
+    obj = mock('5')
+    def obj.to_int() 5 end
+    "str".byterindex("st", obj).should == 0
+
+    obj = mock('5')
+    def obj.respond_to?(arg, *) true end
+    def obj.method_missing(*args) 5 end
+    "str".byterindex("st", obj).should == 0
+  end
+
+  it "raises a TypeError when given offset is nil" do
+    -> { "str".byterindex("st", nil) }.should.raise(TypeError)
+  end
+
+  it "handles a substring in a superset encoding" do
+    'abc'.dup.force_encoding(Encoding::US_ASCII).byterindex('é').should == nil
+  end
+
+  it "handles a substring in a subset encoding" do
+    'été'.byterindex('t'.dup.force_encoding(Encoding::US_ASCII)).should == 2
+  end
+end
+
+describe "String#byterindex with Regexp" do
+  it "behaves the same as String#byterindex(string) for escaped string regexps" do
+    ["blablabla", "hello cruel world...!"].each do |str|
+      ["", "b", "bla", "lab", "o c", "d."].each do |needle|
+        regexp = Regexp.new(Regexp.escape(needle))
+        str.byterindex(regexp).should == str.byterindex(needle)
+
+        0.upto(str.size + 1) do |start|
+          str.byterindex(regexp, start).should == str.byterindex(needle, start)
+        end
+
+        (-str.size - 1).upto(-1) do |start|
+          str.byterindex(regexp, start).should == str.byterindex(needle, start)
+        end
+      end
+    end
+  end
+
+  it "returns the index of the first match from the end of string of regexp" do
+    "blablabla".byterindex(/bla/).should == 6
+    "blablabla".byterindex(/BLA/i).should == 6
+
+    "blablabla".byterindex(/.{0}/).should == 9
+    "blablabla".byterindex(/.{1}/).should == 8
+    "blablabla".byterindex(/.{2}/).should == 7
+    "blablabla".byterindex(/.{6}/).should == 3
+    "blablabla".byterindex(/.{9}/).should == 0
+
+    "blablabla".byterindex(/.*/).should == 9
+    "blablabla".byterindex(/.+/).should == 8
+
+    "blablabla".byterindex(/bla|a/).should == 8
+
+    not_supported_on :opal do
+      "blablabla".byterindex(/\A/).should == 0
+      "blablabla".byterindex(/\Z/).should == 9
+      "blablabla".byterindex(/\z/).should == 9
+      "blablabla\n".byterindex(/\Z/).should == 10
+      "blablabla\n".byterindex(/\z/).should == 10
+    end
+
+    "blablabla".byterindex(/^/).should == 0
+    not_supported_on :opal do
+      "\nblablabla".byterindex(/^/).should == 1
+      "b\nlablabla".byterindex(/^/).should == 2
+    end
+    "blablabla".byterindex(/$/).should == 9
+
+    "blablabla".byterindex(/.l./).should == 6
+  end
+
+  it "starts the search at the given offset" do
+    "blablabla".byterindex(/.{0}/, 5).should == 5
+    "blablabla".byterindex(/.{1}/, 5).should == 5
+    "blablabla".byterindex(/.{2}/, 5).should == 5
+    "blablabla".byterindex(/.{3}/, 5).should == 5
+    "blablabla".byterindex(/.{4}/, 5).should == 5
+
+    "blablabla".byterindex(/.{0}/, 3).should == 3
+    "blablabla".byterindex(/.{1}/, 3).should == 3
+    "blablabla".byterindex(/.{2}/, 3).should == 3
+    "blablabla".byterindex(/.{5}/, 3).should == 3
+    "blablabla".byterindex(/.{6}/, 3).should == 3
+
+    "blablabla".byterindex(/.l./, 0).should == 0
+    "blablabla".byterindex(/.l./, 1).should == 0
+    "blablabla".byterindex(/.l./, 2).should == 0
+    "blablabla".byterindex(/.l./, 3).should == 3
+
+    "blablablax".byterindex(/.x/, 10).should == 8
+    "blablablax".byterindex(/.x/, 9).should == 8
+    "blablablax".byterindex(/.x/, 8).should == 8
+
+    "blablablax".byterindex(/..x/, 10).should == 7
+    "blablablax".byterindex(/..x/, 9).should == 7
+    "blablablax".byterindex(/..x/, 8).should == 7
+    "blablablax".byterindex(/..x/, 7).should == 7
+
+    not_supported_on :opal do
+      "blablabla\n".byterindex(/\Z/, 9).should == 9
+    end
+  end
+
+  it "starts the search at offset + self.length if offset is negative" do
+    str = "blablabla"
+
+    ["bl", "bla", "blab", "la", "lab", "ab", ""].each do |needle|
+      (-str.length .. -1).each do |offset|
+        str.byterindex(needle, offset).should ==
+        str.byterindex(needle, offset + str.length)
+      end
+    end
+  end
+
+  it "returns nil if the substring isn't found" do
+    "blablabla".byterindex(/BLA/).should == nil
+    "blablabla".byterindex(/.{10}/).should == nil
+    "blablablax".byterindex(/.x/, 7).should == nil
+    "blablablax".byterindex(/..x/, 6).should == nil
+
+    not_supported_on :opal do
+      "blablabla".byterindex(/\Z/, 5).should == nil
+      "blablabla".byterindex(/\z/, 5).should == nil
+      "blablabla\n".byterindex(/\z/, 9).should == nil
+    end
+  end
+
+  not_supported_on :opal do
+    it "supports \\G which matches at the given start offset" do
+      "helloYOU.".byterindex(/YOU\G/, 8).should == 5
+      "helloYOU.".byterindex(/YOU\G/).should == nil
+
+      idx = "helloYOUall!".index("YOU")
+      re = /YOU.+\G.+/
+      # The # marks where \G will match.
+      [
+        ["helloYOU#all.", nil],
+        ["helloYOUa#ll.", idx],
+        ["helloYOUal#l.", idx],
+        ["helloYOUall#.", idx],
+        ["helloYOUall.#", nil]
+      ].each do |i|
+        start = i[0].index("#")
+        str = i[0].delete("#")
+
+        str.byterindex(re, start).should == i[1]
+      end
+    end
+  end
+
+  it "tries to convert start_offset to an integer" do
+    obj = mock('5')
+    def obj.to_int() 5 end
+    "str".byterindex(/../, obj).should == 1
+
+    obj = mock('5')
+    def obj.respond_to?(arg, *) true end
+    def obj.method_missing(*args); 5; end
+    "str".byterindex(/../, obj).should == 1
+  end
+
+  it "raises a TypeError when given offset is nil" do
+    -> { "str".byterindex(/../, nil) }.should.raise(TypeError)
+  end
+
+  it "returns the reverse byte index of a multibyte character" do
+    "ありがりがとう".byterindex("が").should == 12
+    "ありがりがとう".byterindex(/が/).should == 12
+  end
+
+  it "returns the character index before the finish" do
+    "ありがりがとう".byterindex("が", 9).should == 6
+    "ありがりがとう".byterindex(/が/, 9).should == 6
+  end
+end
diff --git a/spec/ruby/core/string/bytes_spec.rb b/spec/ruby/core/string/bytes_spec.rb
index 96f1ae9cf2..e6019fb987 100644
--- a/spec/ruby/core/string/bytes_spec.rb
+++ b/spec/ruby/core/string/bytes_spec.rb
@@ -9,7 +9,7 @@ describe "String#bytes" do
   end
 
   it "returns an Array when no block is given" do
-    @utf8.bytes.should be_an_instance_of(Array)
+    @utf8.bytes.should.instance_of?(Array)
   end
 
   it "yields each byte to a block if one is given, returning self" do
@@ -22,9 +22,9 @@ describe "String#bytes" do
     @utf8_ascii.bytes.to_a.size.should == @utf8_ascii.bytesize
   end
 
-  it "returns bytes as Fixnums" do
-    @ascii.bytes.to_a.each {|b| b.should be_an_instance_of(Fixnum)}
-    @utf8_ascii.bytes { |b| b.should be_an_instance_of(Fixnum) }
+  it "returns bytes as Integers" do
+    @ascii.bytes.to_a.each {|b| b.should.instance_of?(Integer)}
+    @utf8_ascii.bytes { |b| b.should.instance_of?(Integer) }
   end
 
   it "agrees with #unpack('C*')" do
@@ -50,6 +50,6 @@ describe "String#bytes" do
   end
 
   it "is unaffected by #force_encoding" do
-    @utf8.force_encoding('ASCII').bytes.to_a.should == @utf8.bytes.to_a
+    @utf8.dup.force_encoding('ASCII').bytes.to_a.should == @utf8.bytes.to_a
   end
 end
diff --git a/spec/ruby/core/string/bytesize_spec.rb b/spec/ruby/core/string/bytesize_spec.rb
index b8b07cfbec..2bbefc0820 100644
--- a/spec/ruby/core/string/bytesize_spec.rb
+++ b/spec/ruby/core/string/bytesize_spec.rb
@@ -2,7 +2,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-describe "#String#bytesize" do
+describe "String#bytesize" do
   it "returns the length of self in bytes" do
     "hello".bytesize.should == 5
     " ".bytesize.should == 1
@@ -13,21 +13,21 @@ describe "#String#bytesize" do
   end
 
   it "works with pseudo-ASCII strings containing single UTF-8 characters" do
-    "\u{6666}".force_encoding('ASCII').bytesize.should == 3
+    "\u{6666}".dup.force_encoding('ASCII').bytesize.should == 3
   end
 
   it "works with strings containing UTF-8 characters" do
-    "c \u{6666}".force_encoding('UTF-8').bytesize.should == 5
+    "c \u{6666}".dup.force_encoding('UTF-8').bytesize.should == 5
     "c \u{6666}".bytesize.should == 5
   end
 
   it "works with pseudo-ASCII strings containing UTF-8 characters" do
-    "c \u{6666}".force_encoding('ASCII').bytesize.should == 5
+    "c \u{6666}".dup.force_encoding('ASCII').bytesize.should == 5
   end
 
   it "returns 0 for the empty string" do
     "".bytesize.should == 0
-    "".force_encoding('ASCII').bytesize.should == 0
-    "".force_encoding('UTF-8').bytesize.should == 0
+    "".dup.force_encoding('ASCII').bytesize.should == 0
+    "".dup.force_encoding('UTF-8').bytesize.should == 0
   end
 end
diff --git a/spec/ruby/core/string/byteslice_spec.rb b/spec/ruby/core/string/byteslice_spec.rb
index a49da040eb..4ad9e8d8f1 100644
--- a/spec/ruby/core/string/byteslice_spec.rb
+++ b/spec/ruby/core/string/byteslice_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/slice'
@@ -17,11 +17,17 @@ describe "String#byteslice with Range" do
   it_behaves_like :string_slice_range, :byteslice
 end
 
-describe "String#byteslice on on non ASCII strings" do
+describe "String#byteslice on non ASCII strings" do
   it "returns byteslice of unicode strings" do
-    "\u3042".byteslice(1).should == "\x81".force_encoding("UTF-8")
-    "\u3042".byteslice(1, 2).should == "\x81\x82".force_encoding("UTF-8")
-    "\u3042".byteslice(1..2).should == "\x81\x82".force_encoding("UTF-8")
-    "\u3042".byteslice(-1).should == "\x82".force_encoding("UTF-8")
+    "\u3042".byteslice(1).should == "\x81".dup.force_encoding("UTF-8")
+    "\u3042".byteslice(1, 2).should == "\x81\x82".dup.force_encoding("UTF-8")
+    "\u3042".byteslice(1..2).should == "\x81\x82".dup.force_encoding("UTF-8")
+    "\u3042".byteslice(-1).should == "\x82".dup.force_encoding("UTF-8")
+  end
+
+  it "returns a String in the same encoding as self" do
+    "ruby".encode("UTF-8").slice(0).encoding.should == Encoding::UTF_8
+    "ruby".encode("US-ASCII").slice(0).encoding.should == Encoding::US_ASCII
+    "ruby".encode("Windows-1251").slice(0).encoding.should == Encoding::Windows_1251
   end
 end
diff --git a/spec/ruby/core/string/bytesplice_spec.rb b/spec/ruby/core/string/bytesplice_spec.rb
new file mode 100644
index 0000000000..3e5e6fe1ee
--- /dev/null
+++ b/spec/ruby/core/string/bytesplice_spec.rb
@@ -0,0 +1,290 @@
+# -*- encoding: utf-8 -*-
+# frozen_string_literal: false
+require_relative '../../spec_helper'
+
+describe "String#bytesplice" do
+  it "raises IndexError when index is less than -bytesize" do
+    -> { "hello".bytesplice(-6, 0, "xxx") }.should.raise(IndexError, "index -6 out of string")
+  end
+
+  it "raises IndexError when index is greater than bytesize" do
+    -> { "hello".bytesplice(6, 0, "xxx") }.should.raise(IndexError, "index 6 out of string")
+  end
+
+  it "raises IndexError for negative length" do
+    -> { "abc".bytesplice(0, -2, "") }.should.raise(IndexError, "negative length -2")
+  end
+
+  it "replaces with integer indices" do
+    "hello".bytesplice(-5, 0, "xxx").should == "xxxhello"
+    "hello".bytesplice(0, 0, "xxx").should == "xxxhello"
+    "hello".bytesplice(0, 1, "xxx").should == "xxxello"
+    "hello".bytesplice(0, 5, "xxx").should == "xxx"
+    "hello".bytesplice(0, 6, "xxx").should == "xxx"
+  end
+
+  it "raises RangeError when range left boundary is less than -bytesize" do
+    -> { "hello".bytesplice(-6...-6, "xxx") }.should.raise(RangeError, "-6...-6 out of range")
+  end
+
+  it "replaces with ranges" do
+    "hello".bytesplice(-5...-5, "xxx").should == "xxxhello"
+    "hello".bytesplice(0...0, "xxx").should == "xxxhello"
+    "hello".bytesplice(0..0, "xxx").should == "xxxello"
+    "hello".bytesplice(0...1, "xxx").should == "xxxello"
+    "hello".bytesplice(0..1, "xxx").should == "xxxllo"
+    "hello".bytesplice(0..-1, "xxx").should == "xxx"
+    "hello".bytesplice(0...5, "xxx").should == "xxx"
+    "hello".bytesplice(0...6, "xxx").should == "xxx"
+  end
+
+  it "raises TypeError when integer index is provided without length argument" do
+    -> { "hello".bytesplice(0, "xxx") }.should.raise(TypeError, "wrong argument type Integer (expected Range)")
+  end
+
+  it "replaces on an empty string" do
+    "".bytesplice(0, 0, "").should == ""
+    "".bytesplice(0, 0, "xxx").should == "xxx"
+  end
+
+  it "mutates self" do
+    s = "hello"
+    s.bytesplice(2, 1, "xxx").should.equal?(s)
+  end
+
+  it "raises when string is frozen" do
+    s = "hello".freeze
+    -> { s.bytesplice(2, 1, "xxx") }.should.raise(FrozenError, "can't modify frozen String: \"hello\"")
+  end
+
+  it "raises IndexError when str_index is less than -bytesize" do
+    -> { "hello".bytesplice(2, 1, "HELLO", -6, 0) }.should.raise(IndexError, "index -6 out of string")
+  end
+
+  it "raises IndexError when str_index is greater than bytesize" do
+    -> { "hello".bytesplice(2, 1, "HELLO", 6, 0) }.should.raise(IndexError, "index 6 out of string")
+  end
+
+  it "raises IndexError for negative str length" do
+    -> { "abc".bytesplice(0, 1, "", 0, -2) }.should.raise(IndexError, "negative length -2")
+  end
+
+  it "replaces with integer str indices" do
+    "hello".bytesplice(1, 2, "HELLO", -5, 0).should == "hlo"
+    "hello".bytesplice(1, 2, "HELLO", 0, 0).should == "hlo"
+    "hello".bytesplice(1, 2, "HELLO", 0, 1).should == "hHlo"
+    "hello".bytesplice(1, 2, "HELLO", 0, 5).should == "hHELLOlo"
+    "hello".bytesplice(1, 2, "HELLO", 0, 6).should == "hHELLOlo"
+  end
+
+  it "raises RangeError when str range left boundary is less than -bytesize" do
+    -> { "hello".bytesplice(0..1, "HELLO", -6...-6) }.should.raise(RangeError, "-6...-6 out of range")
+  end
+
+  it "replaces with str ranges" do
+    "hello".bytesplice(1..2, "HELLO", -5...-5).should == "hlo"
+    "hello".bytesplice(1..2, "HELLO", 0...0).should == "hlo"
+    "hello".bytesplice(1..2, "HELLO", 0..0).should == "hHlo"
+    "hello".bytesplice(1..2, "HELLO", 0...1).should == "hHlo"
+    "hello".bytesplice(1..2, "HELLO", 0..1).should == "hHElo"
+    "hello".bytesplice(1..2, "HELLO", 0..-1).should == "hHELLOlo"
+    "hello".bytesplice(1..2, "HELLO", 0...5).should == "hHELLOlo"
+    "hello".bytesplice(1..2, "HELLO", 0...6).should == "hHELLOlo"
+  end
+
+  it "raises ArgumentError when integer str index is provided without str length argument" do
+    -> { "hello".bytesplice(0, 1, "xxx", 0) }.should.raise(ArgumentError, "wrong number of arguments (given 4, expected 2, 3, or 5)")
+  end
+
+  it "replaces on an empty string with str index/length" do
+    "".bytesplice(0, 0, "", 0, 0).should == ""
+    "".bytesplice(0, 0, "xxx", 0, 1).should == "x"
+  end
+
+  it "mutates self with substring and str index/length" do
+    s = "hello"
+    s.bytesplice(2, 1, "xxx", 1, 2).should.equal?(s)
+    s.should.eql?("hexxlo")
+  end
+
+  it "raises when string is frozen and str index/length" do
+    s = "hello".freeze
+    -> { s.bytesplice(2, 1, "xxx", 0, 1) }.should.raise(FrozenError, "can't modify frozen String: \"hello\"")
+  end
+
+  it "replaces on an empty string with str range" do
+    "".bytesplice(0..0, "", 0..0).should == ""
+    "".bytesplice(0..0, "xyz", 0..1).should == "xy"
+  end
+
+  it "mutates self with substring and str range" do
+    s = "hello"
+    s.bytesplice(2..2, "xyz", 1..2).should.equal?(s)
+    s.should.eql?("heyzlo")
+  end
+
+  it "raises when string is frozen and str range" do
+    s = "hello".freeze
+    -> { s.bytesplice(2..2, "yzx", 0..1) }.should.raise(FrozenError, "can't modify frozen String: \"hello\"")
+  end
+end
+
+describe "String#bytesplice with multibyte characters" do
+  it "raises IndexError when index is out of byte size boundary" do
+    -> { "こんにちは".bytesplice(-16, 0, "xxx") }.should.raise(IndexError, "index -16 out of string")
+  end
+
+  it "raises IndexError when index is not on a codepoint boundary" do
+    -> { "こんにちは".bytesplice(1, 0, "xxx") }.should.raise(IndexError, "offset 1 does not land on character boundary")
+  end
+
+  it "raises IndexError when length is not matching the codepoint boundary" do
+    -> { "こんにちは".bytesplice(0, 1, "xxx") }.should.raise(IndexError, "offset 1 does not land on character boundary")
+    -> { "こんにちは".bytesplice(0, 2, "xxx") }.should.raise(IndexError, "offset 2 does not land on character boundary")
+  end
+
+  it "replaces with integer indices" do
+    "こんにちは".bytesplice(-15, 0, "xxx").should == "xxxこんにちは"
+    "こんにちは".bytesplice(0, 0, "xxx").should == "xxxこんにちは"
+    "こんにちは".bytesplice(0, 3, "xxx").should == "xxxんにちは"
+    "こんにちは".bytesplice(3, 3, "はは").should == "こははにちは"
+    "こんにちは".bytesplice(15, 0, "xxx").should == "こんにちはxxx"
+  end
+
+  it "replaces with range" do
+    "こんにちは".bytesplice(-15...-16, "xxx").should == "xxxこんにちは"
+    "こんにちは".bytesplice(0...0, "xxx").should == "xxxこんにちは"
+    "こんにちは".bytesplice(0..2, "xxx").should == "xxxんにちは"
+    "こんにちは".bytesplice(0...3, "xxx").should == "xxxんにちは"
+    "こんにちは".bytesplice(0..5, "xxx").should == "xxxにちは"
+    "こんにちは".bytesplice(0..-1, "xxx").should == "xxx"
+    "こんにちは".bytesplice(0...15, "xxx").should == "xxx"
+    "こんにちは".bytesplice(0...18, "xxx").should == "xxx"
+  end
+
+  it "treats negative length for range as 0" do
+    "こんにちは".bytesplice(0...-100, "xxx").should == "xxxこんにちは"
+    "こんにちは".bytesplice(3...-100, "xxx").should == "こxxxんにちは"
+    "こんにちは".bytesplice(-15...-100, "xxx").should == "xxxこんにちは"
+  end
+
+  it "raises when ranges not match codepoint boundaries" do
+    -> { "こんにちは".bytesplice(0..0, "x") }.should.raise(IndexError, "offset 1 does not land on character boundary")
+    -> { "こんにちは".bytesplice(0..1, "x") }.should.raise(IndexError, "offset 2 does not land on character boundary")
+    # Begin is incorrect
+    -> { "こんにちは".bytesplice(-4..-1, "x") }.should.raise(IndexError, "offset 11 does not land on character boundary")
+    -> { "こんにちは".bytesplice(-5..-1, "x") }.should.raise(IndexError, "offset 10 does not land on character boundary")
+    # End is incorrect
+    -> { "こんにちは".bytesplice(-3..-2, "x") }.should.raise(IndexError, "offset 14 does not land on character boundary")
+    -> { "こんにちは".bytesplice(-3..-3, "x") }.should.raise(IndexError, "offset 13 does not land on character boundary")
+  end
+
+  it "deals with a different encoded argument" do
+    s = "こんにちは"
+    s.encoding.should == Encoding::UTF_8
+    sub = "xxxxxx"
+    sub.force_encoding(Encoding::US_ASCII)
+
+    result = s.bytesplice(0, 3, sub)
+    result.should == "xxxxxxんにちは"
+    result.encoding.should == Encoding::UTF_8
+
+    s = "xxxxxx"
+    s.force_encoding(Encoding::US_ASCII)
+    sub = "こんにちは"
+    sub.encoding.should == Encoding::UTF_8
+
+    result = s.bytesplice(0, 3, sub)
+    result.should == "こんにちはxxx"
+    result.encoding.should == Encoding::UTF_8
+  end
+
+  it "raises IndexError when str_index is out of byte size boundary" do
+    -> { "こんにちは".bytesplice(3, 3, "こんにちは", -16, 0) }.should.raise(IndexError, "index -16 out of string")
+  end
+
+  it "raises IndexError when str_index is not on a codepoint boundary" do
+    -> { "こんにちは".bytesplice(3, 3, "こんにちは", 1, 0) }.should.raise(IndexError, "offset 1 does not land on character boundary")
+  end
+
+  it "raises IndexError when str_length is not matching the codepoint boundary" do
+    -> { "こんにちは".bytesplice(3, 3, "こんにちは", 0, 1) }.should.raise(IndexError, "offset 1 does not land on character boundary")
+    -> { "こんにちは".bytesplice(3, 3, "こんにちは", 0, 2) }.should.raise(IndexError, "offset 2 does not land on character boundary")
+  end
+
+  it "replaces with integer str indices" do
+    "こんにちは".bytesplice(3, 3, "こんにちは", -15, 0).should == "こにちは"
+    "こんにちは".bytesplice(3, 3, "こんにちは", 0, 0).should == "こにちは"
+    "こんにちは".bytesplice(3, 3, "こんにちは", 0, 3).should == "ここにちは"
+    "こんにちは".bytesplice(3, 3, "はは", 3, 3).should == "こはにちは"
+    "こんにちは".bytesplice(3, 3, "こんにちは", 15, 0).should == "こにちは"
+  end
+
+  it "replaces with str range" do
+    "こんにちは".bytesplice(0..2, "こんにちは", -15...-16).should == "んにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 0...0).should == "んにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 3..5).should == "んんにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 3...6).should == "んんにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 3..8).should == "んにんにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 0..-1).should == "こんにちはんにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 0...15).should == "こんにちはんにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 0...18).should == "こんにちはんにちは"
+  end
+
+  it "treats negative length for str range as 0" do
+    "こんにちは".bytesplice(0..2, "こんにちは", 0...-100).should == "んにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", 3...-100).should == "んにちは"
+    "こんにちは".bytesplice(0..2, "こんにちは", -15...-100).should == "んにちは"
+  end
+
+  it "raises when ranges not match codepoint boundaries in str" do
+    -> { "こんにちは".bytesplice(3...3, "こ", 0..0) }.should.raise(IndexError, "offset 1 does not land on character boundary")
+    -> { "こんにちは".bytesplice(3...3, "こ", 0..1) }.should.raise(IndexError, "offset 2 does not land on character boundary")
+    # Begin is incorrect
+    -> { "こんにちは".bytesplice(3...3, "こんにちは", -4..-1) }.should.raise(IndexError, "offset 11 does not land on character boundary")
+    -> { "こんにちは".bytesplice(3...3, "こんにちは", -5..-1) }.should.raise(IndexError, "offset 10 does not land on character boundary")
+    # End is incorrect
+    -> { "こんにちは".bytesplice(3...3, "こんにちは", -3..-2) }.should.raise(IndexError, "offset 14 does not land on character boundary")
+    -> { "こんにちは".bytesplice(3...3, "こんにちは", -3..-3) }.should.raise(IndexError, "offset 13 does not land on character boundary")
+  end
+
+  it "deals with a different encoded argument with str index/length" do
+    s = "こんにちは"
+    s.encoding.should == Encoding::UTF_8
+    sub = "goodbye"
+    sub.force_encoding(Encoding::US_ASCII)
+
+    result = s.bytesplice(3, 3, sub, 0, 3)
+    result.should == "こgooにちは"
+    result.encoding.should == Encoding::UTF_8
+
+    s = "hello"
+    s.force_encoding(Encoding::US_ASCII)
+    sub = "こんにちは"
+    sub.encoding.should == Encoding::UTF_8
+
+    result = s.bytesplice(1, 2, sub, 3, 3)
+    result.should == "hんlo"
+    result.encoding.should == Encoding::UTF_8
+  end
+
+  it "deals with a different encoded argument with str range" do
+    s = "こんにちは"
+    s.encoding.should == Encoding::UTF_8
+    sub = "goodbye"
+    sub.force_encoding(Encoding::US_ASCII)
+
+    result = s.bytesplice(3..5, sub, 0..2)
+    result.should == "こgooにちは"
+    result.encoding.should == Encoding::UTF_8
+
+    s = "hello"
+    s.force_encoding(Encoding::US_ASCII)
+    sub = "こんにちは"
+    sub.encoding.should == Encoding::UTF_8
+
+    result = s.bytesplice(1..2, sub, 3..5)
+    result.should == "hんlo"
+    result.encoding.should == Encoding::UTF_8
+  end
+end
diff --git a/spec/ruby/core/string/capitalize_spec.rb b/spec/ruby/core/string/capitalize_spec.rb
index df64cdaa3b..12b1675c2e 100644
--- a/spec/ruby/core/string/capitalize_spec.rb
+++ b/spec/ruby/core/string/capitalize_spec.rb
@@ -10,11 +10,7 @@ describe "String#capitalize" do
     "hello".capitalize.should == "Hello"
     "HELLO".capitalize.should == "Hello"
     "123ABC".capitalize.should == "123abc"
-  end
-
-  it "taints resulting string when self is tainted" do
-    "".taint.capitalize.tainted?.should == true
-    "hello".taint.capitalize.tainted?.should == true
+    "abcdef"[1...-1].capitalize.should == "Bcde"
   end
 
   describe "full Unicode case mapping" do
@@ -32,7 +28,7 @@ describe "String#capitalize" do
       capitalized.should == "Sset"
       capitalized.size.should == 4
       capitalized.bytesize.should == 4
-      capitalized.ascii_only?.should be_true
+      capitalized.ascii_only?.should == true
     end
   end
 
@@ -40,6 +36,10 @@ describe "String#capitalize" do
     it "does not capitalize non-ASCII characters" do
       "ßet".capitalize(:ascii).should == "ßet"
     end
+
+    it "handles non-ASCII substrings properly" do
+      "garçon"[1...-1].capitalize(:ascii).should == "Arço"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -52,7 +52,7 @@ describe "String#capitalize" do
     end
 
     it "does not allow any other additional option" do
-      -> { "iSa".capitalize(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { "iSa".capitalize(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -66,120 +66,142 @@ describe "String#capitalize" do
     end
 
     it "does not allow any other additional option" do
-      -> { "iß".capitalize(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { "iß".capitalize(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { "abc".capitalize(:fold) }.should raise_error(ArgumentError)
+    -> { "abc".capitalize(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { "abc".capitalize(:invalid_option) }.should raise_error(ArgumentError)
+    -> { "abc".capitalize(:invalid_option) }.should.raise(ArgumentError)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("hello").capitalize.should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("Hello").capitalize.should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("hello").capitalize.should.instance_of?(String)
+    StringSpecs::MyString.new("Hello").capitalize.should.instance_of?(String)
+  end
+
+  it "returns a String in the same encoding as self" do
+    "h".encode("US-ASCII").capitalize.encoding.should == Encoding::US_ASCII
   end
 end
 
 describe "String#capitalize!" do
   it "capitalizes self in place" do
-    a = "hello"
-    a.capitalize!.should equal(a)
+    a = +"hello"
+    a.capitalize!.should.equal?(a)
     a.should == "Hello"
   end
 
+  it "modifies self in place for non-ascii-compatible encodings" do
+    a = "heLLo".encode("utf-16le")
+    a.capitalize!
+    a.should == "Hello".encode("utf-16le")
+  end
+
   describe "full Unicode case mapping" do
     it "modifies self in place for all of Unicode with no option" do
-      a = "äöÜ"
+      a = +"äöÜ"
       a.capitalize!
       a.should == "Äöü"
     end
 
     it "only capitalizes the first resulting character when upcasing a character produces a multi-character sequence" do
-      a = "ß"
+      a = +"ß"
       a.capitalize!
       a.should == "Ss"
     end
 
+    it "works for non-ascii-compatible encodings" do
+      a = "äöü".encode("utf-16le")
+      a.capitalize!
+      a.should == "Äöü".encode("utf-16le")
+    end
+
     it "updates string metadata" do
-      capitalized = "ßeT"
+      capitalized = +"ßeT"
       capitalized.capitalize!
 
       capitalized.should == "Sset"
       capitalized.size.should == 4
       capitalized.bytesize.should == 4
-      capitalized.ascii_only?.should be_true
+      capitalized.ascii_only?.should == true
     end
   end
 
   describe "modifies self in place for ASCII-only case mapping" do
     it "does not capitalize non-ASCII characters" do
-      a = "ßet"
+      a = +"ßet"
       a.capitalize!(:ascii)
       a.should == "ßet"
     end
+
+    it "works for non-ascii-compatible encodings" do
+      a = "aBc".encode("utf-16le")
+      a.capitalize!(:ascii)
+      a.should == "Abc".encode("utf-16le")
+    end
   end
 
   describe "modifies self in place for full Unicode case mapping adapted for Turkic languages" do
     it "capitalizes ASCII characters according to Turkic semantics" do
-      a = "iSa"
+      a = +"iSa"
       a.capitalize!(:turkic)
       a.should == "İsa"
     end
 
     it "allows Lithuanian as an extra option" do
-      a = "iSa"
+      a = +"iSa"
       a.capitalize!(:turkic, :lithuanian)
       a.should == "İsa"
     end
 
     it "does not allow any other additional option" do
-      -> { a = "iSa"; a.capitalize!(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "iSa"; a.capitalize!(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   describe "modifies self in place for full Unicode case mapping adapted for Lithuanian" do
     it "currently works the same as full Unicode case mapping" do
-      a = "iß"
+      a = +"iß"
       a.capitalize!(:lithuanian)
       a.should == "Iß"
     end
 
     it "allows Turkic as an extra option (and applies Turkic semantics)" do
-      a = "iß"
+      a = +"iß"
       a.capitalize!(:lithuanian, :turkic)
       a.should == "İß"
     end
 
     it "does not allow any other additional option" do
-      -> { a = "iß"; a.capitalize!(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "iß"; a.capitalize!(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { a = "abc"; a.capitalize!(:fold) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.capitalize!(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { a = "abc"; a.capitalize!(:invalid_option) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.capitalize!(:invalid_option) }.should.raise(ArgumentError)
   end
 
   it "returns nil when no changes are made" do
-    a = "Hello"
+    a = +"Hello"
     a.capitalize!.should == nil
     a.should == "Hello"
 
-    "".capitalize!.should == nil
-    "H".capitalize!.should == nil
+    (+"").capitalize!.should == nil
+    (+"H").capitalize!.should == nil
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     ["", "Hello", "hello"].each do |a|
       a.freeze
-      -> { a.capitalize! }.should raise_error(frozen_error_class)
+      -> { a.capitalize! }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/string/casecmp_spec.rb b/spec/ruby/core/string/casecmp_spec.rb
index 01b22e8f13..90577aaac0 100644
--- a/spec/ruby/core/string/casecmp_spec.rb
+++ b/spec/ruby/core/string/casecmp_spec.rb
@@ -25,20 +25,12 @@ describe "String#casecmp independent of case" do
     "abc".casecmp(other).should == 0
   end
 
-  ruby_version_is ""..."2.5" do
-    it "raises a TypeError if other can't be converted to a string" do
-      -> { "abc".casecmp(mock('abc')) }.should raise_error(TypeError)
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "returns nil if other can't be converted to a string" do
-      "abc".casecmp(mock('abc')).should be_nil
-    end
+  it "returns nil if other can't be converted to a string" do
+    "abc".casecmp(mock('abc')).should == nil
   end
 
   it "returns nil if incompatible encodings" do
-    "あれ".casecmp("れ".encode(Encoding::EUC_JP)).should be_nil
+    "あれ".casecmp("れ".encode(Encoding::EUC_JP)).should == nil
   end
 
   describe "in UTF-8 mode" do
@@ -125,6 +117,11 @@ describe "String#casecmp independent of case" do
       "B".casecmp(a).should == 1
     end
   end
+
+  it "returns 0 for empty strings in different encodings" do
+    ''.b.casecmp('').should == 0
+    ''.b.casecmp(''.encode("UTF-32LE")).should == 0
+  end
 end
 
 describe 'String#casecmp? independent of case' do
@@ -146,7 +143,7 @@ describe 'String#casecmp? independent of case' do
   end
 
   it "returns nil if incompatible encodings" do
-    "あれ".casecmp?("れ".encode(Encoding::EUC_JP)).should be_nil
+    "あれ".casecmp?("れ".encode(Encoding::EUC_JP)).should == nil
   end
 
   describe 'for UNICODE characters' do
@@ -193,18 +190,15 @@ describe 'String#casecmp? independent of case' do
   end
 
   it "case folds" do
-    "ß".casecmp?("ss").should be_true
+    "ß".casecmp?("ss").should == true
   end
 
-  ruby_version_is "2.4"..."2.5" do
-    it "raises a TypeError if other can't be converted to a string" do
-      -> { "abc".casecmp?(mock('abc')) }.should raise_error(TypeError)
-    end
+  it "returns nil if other can't be converted to a string" do
+    "abc".casecmp?(mock('abc')).should == nil
   end
 
-  ruby_version_is "2.5" do
-    it "returns nil if other can't be converted to a string" do
-      "abc".casecmp?(mock('abc')).should be_nil
-    end
+  it "returns true for empty strings in different encodings" do
+    ''.b.should.casecmp?('')
+    ''.b.should.casecmp?(''.encode("UTF-32LE"))
   end
 end
diff --git a/spec/ruby/core/string/center_spec.rb b/spec/ruby/core/string/center_spec.rb
index 27f8b7387f..ac5b8a2ff3 100644
--- a/spec/ruby/core/string/center_spec.rb
+++ b/spec/ruby/core/string/center_spec.rb
@@ -47,14 +47,6 @@ describe "String#center with length, padding" do
     "radiology".center(8, '-').should == "radiology"
   end
 
-  it "taints result when self or padstr is tainted" do
-    "x".taint.center(4).tainted?.should == true
-    "x".taint.center(0).tainted?.should == true
-    "".taint.center(0).tainted?.should == true
-    "x".taint.center(4, "*").tainted?.should == true
-    "x".center(4, "*".taint).tainted?.should == true
-  end
-
   it "calls #to_int to convert length to an integer" do
     "_".center(3.8, "^").should == "^_^"
 
@@ -65,10 +57,10 @@ describe "String#center with length, padding" do
   end
 
   it "raises a TypeError when length can't be converted to an integer" do
-    -> { "hello".center("x")       }.should raise_error(TypeError)
-    -> { "hello".center("x", "y")  }.should raise_error(TypeError)
-    -> { "hello".center([])        }.should raise_error(TypeError)
-    -> { "hello".center(mock('x')) }.should raise_error(TypeError)
+    -> { "hello".center("x")       }.should.raise(TypeError)
+    -> { "hello".center("x", "y")  }.should.raise(TypeError)
+    -> { "hello".center([])        }.should.raise(TypeError)
+    -> { "hello".center(mock('x')) }.should.raise(TypeError)
   end
 
   it "calls #to_str to convert padstr to a String" do
@@ -79,53 +71,47 @@ describe "String#center with length, padding" do
   end
 
   it "raises a TypeError when padstr can't be converted to a string" do
-    -> { "hello".center(20, 100)       }.should raise_error(TypeError)
-    -> { "hello".center(20, [])      }.should raise_error(TypeError)
-    -> { "hello".center(20, mock('x')) }.should raise_error(TypeError)
+    -> { "hello".center(20, 100)       }.should.raise(TypeError)
+    -> { "hello".center(20, [])      }.should.raise(TypeError)
+    -> { "hello".center(20, mock('x')) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if padstr is empty" do
-    -> { "hello".center(10, "") }.should raise_error(ArgumentError)
-    -> { "hello".center(0, "")  }.should raise_error(ArgumentError)
+    -> { "hello".center(10, "") }.should.raise(ArgumentError)
+    -> { "hello".center(0, "")  }.should.raise(ArgumentError)
   end
 
-  it "returns subclass instances when called on subclasses" do
-    StringSpecs::MyString.new("").center(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").center(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").center(10, StringSpecs::MyString.new("x")).should be_an_instance_of(StringSpecs::MyString)
-
-    "".center(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-    "foo".center(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-  end
+  it "returns String instances when called on subclasses" do
+    StringSpecs::MyString.new("").center(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").center(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").center(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
 
-  it "when padding is tainted and self is untainted returns a tainted string if and only if length is longer than self" do
-    "hello".center(4, 'X'.taint).tainted?.should be_false
-    "hello".center(5, 'X'.taint).tainted?.should be_false
-    "hello".center(6, 'X'.taint).tainted?.should be_true
+    "".center(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
+    "foo".center(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
   end
 
   describe "with width" do
     it "returns a String in the same encoding as the original" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.center 6
       result.should == " abc  "
-      result.encoding.should equal(Encoding::IBM437)
+      result.encoding.should.equal?(Encoding::IBM437)
     end
   end
 
   describe "with width, pattern" do
     it "returns a String in the compatible encoding" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.center 6, "あ"
       result.should == "あabcああ"
-      result.encoding.should equal(Encoding::UTF_8)
+      result.encoding.should.equal?(Encoding::UTF_8)
     end
 
     it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
       pat = "ア".encode Encoding::EUC_JP
       -> do
         "あれ".center 5, pat
-      end.should raise_error(Encoding::CompatibilityError)
+      end.should.raise(Encoding::CompatibilityError)
     end
   end
 end
diff --git a/spec/ruby/core/string/chars_spec.rb b/spec/ruby/core/string/chars_spec.rb
index e4f26bc0cc..ee85430574 100644
--- a/spec/ruby/core/string/chars_spec.rb
+++ b/spec/ruby/core/string/chars_spec.rb
@@ -1,5 +1,5 @@
+require_relative "../../spec_helper"
 require_relative 'shared/chars'
-require_relative 'shared/each_char_without_block'
 
 describe "String#chars" do
   it_behaves_like :string_chars, :chars
@@ -7,4 +7,10 @@ describe "String#chars" do
   it "returns an array when no block given" do
     "hello".chars.should == ['h', 'e', 'l', 'l', 'o']
   end
+
+  it "returns Strings in the same encoding as self" do
+    "hello".encode("US-ASCII").chars.each do |c|
+      c.encoding.should == Encoding::US_ASCII
+    end
+  end
 end
diff --git a/spec/ruby/core/string/chilled_string_spec.rb b/spec/ruby/core/string/chilled_string_spec.rb
new file mode 100644
index 0000000000..6a5e846db2
--- /dev/null
+++ b/spec/ruby/core/string/chilled_string_spec.rb
@@ -0,0 +1,151 @@
+require_relative '../../spec_helper'
+
+describe "chilled String" do
+  guard -> { ruby_version_is "3.4" and !"test".equal?("test") } do
+    describe "chilled string literals" do
+
+      describe "#frozen?" do
+        it "returns false" do
+          "chilled".frozen?.should == false
+        end
+      end
+
+      describe "#-@" do
+        it "returns a different instance" do
+          input = "chilled"
+          interned = (-input)
+          interned.frozen?.should == true
+          interned.object_id.should_not == input.object_id
+        end
+      end
+
+      describe "#+@" do
+        it "returns a different instance" do
+          input = "chilled"
+          duped = (+input)
+          duped.frozen?.should == false
+          duped.object_id.should_not == input.object_id
+        end
+      end
+
+      describe "#clone" do
+        it "preserves chilled status" do
+          input = "chilled".clone
+          -> {
+            input << "-mutated"
+          }.should complain(/literal string will be frozen in the future/)
+          input.should == "chilled-mutated"
+        end
+      end
+
+      describe "mutation" do
+        it "emits a warning" do
+          input = "chilled"
+          -> {
+            input << "-mutated"
+          }.should complain(/literal string will be frozen in the future/)
+          input.should == "chilled-mutated"
+        end
+
+        it "emits a warning for concatenated strings" do
+          input = "still" "+chilled"
+          -> {
+            input << "-mutated"
+          }.should complain(/literal string will be frozen in the future/)
+          input.should == "still+chilled-mutated"
+        end
+
+        it "emits a warning on singleton_class creation" do
+          -> {
+            "chilled".singleton_class
+          }.should complain(/literal string will be frozen in the future/)
+        end
+
+        it "emits a warning on instance variable assignment" do
+          -> {
+            "chilled".instance_variable_set(:@ivar, 42)
+          }.should complain(/literal string will be frozen in the future/)
+        end
+
+        it "raises FrozenError after the string was explicitly frozen" do
+          input = "chilled"
+          input.freeze
+          -> {
+            -> {
+              input << "mutated"
+            }.should.raise(FrozenError)
+          }.should_not complain(/literal string will be frozen in the future/)
+        end
+      end
+    end
+
+    describe "chilled strings returned by Symbol#to_s" do
+
+      describe "#frozen?" do
+        it "returns false" do
+          :chilled.to_s.frozen?.should == false
+        end
+      end
+
+      describe "#-@" do
+        it "returns a different instance" do
+          input = :chilled.to_s
+          interned = (-input)
+          interned.frozen?.should == true
+          interned.object_id.should_not == input.object_id
+        end
+      end
+
+      describe "#+@" do
+        it "returns a different instance" do
+          input = :chilled.to_s
+          duped = (+input)
+          duped.frozen?.should == false
+          duped.object_id.should_not == input.object_id
+        end
+      end
+
+      describe "#clone" do
+        it "preserves chilled status" do
+          input = :chilled.to_s.clone
+          -> {
+            input << "-mutated"
+          }.should complain(/string returned by :chilled\.to_s will be frozen in the future/)
+          input.should == "chilled-mutated"
+        end
+      end
+
+      describe "mutation" do
+        it "emits a warning" do
+          input = :chilled.to_s
+          -> {
+            input << "-mutated"
+          }.should complain(/string returned by :chilled\.to_s will be frozen in the future/)
+          input.should == "chilled-mutated"
+        end
+
+        it "emits a warning on singleton_class creation" do
+          -> {
+            :chilled.to_s.singleton_class
+          }.should complain(/string returned by :chilled\.to_s will be frozen in the future/)
+        end
+
+        it "emits a warning on instance variable assignment" do
+          -> {
+            :chilled.to_s.instance_variable_set(:@ivar, 42)
+          }.should complain(/string returned by :chilled\.to_s will be frozen in the future/)
+        end
+
+        it "raises FrozenError after the string was explicitly frozen" do
+          input = :chilled.to_s
+          input.freeze
+          -> {
+            -> {
+              input << "mutated"
+            }.should.raise(FrozenError)
+          }.should_not complain(/string returned by :chilled\.to_s will be frozen in the future/)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/string/chomp_spec.rb b/spec/ruby/core/string/chomp_spec.rb
index 9db47d1dc6..3a8550892f 100644
--- a/spec/ruby/core/string/chomp_spec.rb
+++ b/spec/ruby/core/string/chomp_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -6,11 +7,13 @@ describe "String#chomp" do
   describe "when passed no argument" do
     before do
       # Ensure that $/ is set to the default value
+      @verbose, $VERBOSE = $VERBOSE, nil
       @dollar_slash, $/ = $/, "\n"
     end
 
     after do
       $/ = @dollar_slash
+      $VERBOSE = @verbose
     end
 
     it "does not modify a String with no trailing carriage return or newline" do
@@ -19,7 +22,7 @@ describe "String#chomp" do
 
     it "returns a copy of the String when it is not modified" do
       str = "abc"
-      str.chomp.should_not equal(str)
+      str.chomp.should_not.equal?(str)
     end
 
     it "removes one trailing newline" do
@@ -38,19 +41,23 @@ describe "String#chomp" do
       "".chomp.should == ""
     end
 
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp.tainted?.should be_true
+    it "returns a String in the same encoding as self" do
+      "abc\n\n".encode("US-ASCII").chomp.encoding.should == Encoding::US_ASCII
     end
 
-    it "returns subclass instances when called on a subclass" do
+    it "returns String instances when called on a subclass" do
       str = StringSpecs::MyString.new("hello\n").chomp
-      str.should be_an_instance_of(StringSpecs::MyString)
+      str.should.instance_of?(String)
     end
 
     it "removes trailing characters that match $/ when it has been assigned a value" do
       $/ = "cdef"
       "abcdef".chomp.should == "ab"
     end
+
+    it "removes one trailing newline for string with invalid encoding" do
+      "\xa0\xa1\n".chomp.should == "\xa0\xa1"
+    end
   end
 
   describe "when passed nil" do
@@ -60,11 +67,7 @@ describe "String#chomp" do
 
     it "returns a copy of the String" do
       str = "abc"
-      str.chomp(nil).should_not equal(str)
-    end
-
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp(nil).tainted?.should be_true
+      str.chomp(nil).should_not.equal?(str)
     end
 
     it "returns an empty String when self is empty" do
@@ -93,13 +96,13 @@ describe "String#chomp" do
       "abc\r\n\r\n\r\n".chomp("").should == "abc"
     end
 
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp("").tainted?.should be_true
-    end
-
     it "returns an empty String when self is empty" do
       "".chomp("").should == ""
     end
+
+    it "removes one trailing newline for string with invalid encoding" do
+      "\xa0\xa1\n".chomp("").should == "\xa0\xa1"
+    end
   end
 
   describe "when passed '\\n'" do
@@ -115,10 +118,6 @@ describe "String#chomp" do
       "abc\r\n\r\n".chomp("\n").should == "abc\r\n"
     end
 
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp("\n").tainted?.should be_true
-    end
-
     it "returns an empty String when self is empty" do
       "".chomp("\n").should == ""
     end
@@ -134,7 +133,7 @@ describe "String#chomp" do
     it "raises a TypeError if #to_str does not return a String" do
       arg = mock("string chomp")
       arg.should_receive(:to_str).and_return(1)
-      -> { "abc".chomp(arg) }.should raise_error(TypeError)
+      -> { "abc".chomp(arg) }.should.raise(TypeError)
     end
   end
 
@@ -151,14 +150,6 @@ describe "String#chomp" do
       "".chomp("abc").should == ""
     end
 
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp("abc").tainted?.should be_true
-    end
-
-    it "does not taint the result when the argument is tainted" do
-      "abc".chomp("abc".taint).tainted?.should be_false
-    end
-
     it "returns an empty String when the argument equals self" do
       "abc".chomp("abc").should == ""
     end
@@ -169,20 +160,22 @@ describe "String#chomp!" do
   describe "when passed no argument" do
     before do
       # Ensure that $/ is set to the default value
+      @verbose, $VERBOSE = $VERBOSE, nil
       @dollar_slash, $/ = $/, "\n"
     end
 
     after do
       $/ = @dollar_slash
+      $VERBOSE = @verbose
     end
 
     it "modifies self" do
       str = "abc\n"
-      str.chomp!.should equal(str)
+      str.chomp!.should.equal?(str)
     end
 
     it "returns nil if self is not modified" do
-      "abc".chomp!.should be_nil
+      "abc".chomp!.should == nil
     end
 
     it "removes one trailing newline" do
@@ -198,16 +191,12 @@ describe "String#chomp!" do
     end
 
     it "returns nil when self is empty" do
-      "".chomp!.should be_nil
-    end
-
-    it "taints the result if self is tainted" do
-      "abc\n".taint.chomp!.tainted?.should be_true
+      "".chomp!.should == nil
     end
 
     it "returns subclass instances when called on a subclass" do
       str = StringSpecs::MyString.new("hello\n").chomp!
-      str.should be_an_instance_of(StringSpecs::MyString)
+      str.should.instance_of?(StringSpecs::MyString)
     end
 
     it "removes trailing characters that match $/ when it has been assigned a value" do
@@ -218,11 +207,11 @@ describe "String#chomp!" do
 
   describe "when passed nil" do
     it "returns nil" do
-      "abc\r\n".chomp!(nil).should be_nil
+      "abc\r\n".chomp!(nil).should == nil
     end
 
     it "returns nil when self is empty" do
-      "".chomp!(nil).should be_nil
+      "".chomp!(nil).should == nil
     end
   end
 
@@ -236,7 +225,7 @@ describe "String#chomp!" do
     end
 
     it "does not remove a final carriage return" do
-      "abc\r".chomp!("").should be_nil
+      "abc\r".chomp!("").should == nil
     end
 
     it "removes more than one trailing newlines" do
@@ -247,12 +236,8 @@ describe "String#chomp!" do
       "abc\r\n\r\n\r\n".chomp!("").should == "abc"
     end
 
-    it "taints the result if self is tainted" do
-      "abc\n".taint.chomp!("").tainted?.should be_true
-    end
-
     it "returns nil when self is empty" do
-      "".chomp!("").should be_nil
+      "".chomp!("").should == nil
     end
   end
 
@@ -269,12 +254,8 @@ describe "String#chomp!" do
       "abc\r\n\r\n".chomp!("\n").should == "abc\r\n"
     end
 
-    it "taints the result if self is tainted" do
-      "abc\n".taint.chomp!("\n").tainted?.should be_true
-    end
-
     it "returns nil when self is empty" do
-      "".chomp!("\n").should be_nil
+      "".chomp!("\n").should == nil
     end
   end
 
@@ -288,7 +269,7 @@ describe "String#chomp!" do
     it "raises a TypeError if #to_str does not return a String" do
       arg = mock("string chomp")
       arg.should_receive(:to_str).and_return(1)
-      -> { "abc".chomp!(arg) }.should raise_error(TypeError)
+      -> { "abc".chomp!(arg) }.should.raise(TypeError)
     end
   end
 
@@ -298,45 +279,39 @@ describe "String#chomp!" do
     end
 
     it "returns nil if the argument does not match the trailing characters" do
-      "abc".chomp!("def").should be_nil
+      "abc".chomp!("def").should == nil
     end
 
     it "returns nil when self is empty" do
-      "".chomp!("abc").should be_nil
-    end
-
-    it "taints the result if self is tainted" do
-      "abc".taint.chomp!("abc").tainted?.should be_true
-    end
-
-    it "does not taint the result when the argument is tainted" do
-      "abc".chomp!("abc".taint).tainted?.should be_false
+      "".chomp!("abc").should == nil
     end
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance when it is modified" do
+  it "raises a FrozenError on a frozen instance when it is modified" do
     a = "string\n\r"
     a.freeze
 
-    -> { a.chomp! }.should raise_error(frozen_error_class)
+    -> { a.chomp! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen instance when it would not be modified" do
+  it "raises a FrozenError on a frozen instance when it would not be modified" do
     a = "string\n\r"
     a.freeze
-    -> { a.chomp!(nil) }.should raise_error(frozen_error_class)
-    -> { a.chomp!("x") }.should raise_error(frozen_error_class)
+    -> { a.chomp!(nil) }.should.raise(FrozenError)
+    -> { a.chomp!("x") }.should.raise(FrozenError)
   end
 end
 
 describe "String#chomp" do
   before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
     @before_separator = $/
   end
 
   after :each do
     $/ = @before_separator
+    $VERBOSE = @verbose
   end
 
   it "does not modify a multi-byte character" do
@@ -361,15 +336,17 @@ end
 
 describe "String#chomp!" do
   before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
     @before_separator = $/
   end
 
   after :each do
     $/ = @before_separator
+    $VERBOSE = @verbose
   end
 
   it "returns nil when the String is not modified" do
-    "あれ".chomp!.should be_nil
+    "あれ".chomp!.should == nil
   end
 
   it "removes the final carriage return, newline from a multibyte String" do
diff --git a/spec/ruby/core/string/chop_spec.rb b/spec/ruby/core/string/chop_spec.rb
index 35a5766b2f..2113da543b 100644
--- a/spec/ruby/core/string/chop_spec.rb
+++ b/spec/ruby/core/string/chop_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -46,21 +47,15 @@ describe "String#chop" do
 
   it "returns a new string when applied to an empty string" do
     s = ""
-    s.chop.should_not equal(s)
+    s.chop.should_not.equal?(s)
   end
 
-  it "taints result when self is tainted" do
-    "hello".taint.chop.tainted?.should == true
-    "".taint.chop.tainted?.should == true
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("hello\n").chop.should.instance_of?(String)
   end
 
-  it "untrusts result when self is untrusted" do
-    "hello".untrust.chop.untrusted?.should == true
-    "".untrust.chop.untrusted?.should == true
-  end
-
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("hello\n").chop.should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String in the same encoding as self" do
+    "abc\n\n".encode("US-ASCII").chop.encoding.should == Encoding::US_ASCII
   end
 end
 
@@ -104,21 +99,21 @@ describe "String#chop!" do
 
   it "returns self if modifications were made" do
     str = "hello"
-    str.chop!.should equal(str)
+    str.chop!.should.equal?(str)
   end
 
   it "returns nil when called on an empty string" do
-    "".chop!.should be_nil
+    "".chop!.should == nil
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "string\n\r".freeze.chop! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "string\n\r".freeze.chop! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
+  it "raises a FrozenError on a frozen instance that would not be modified" do
     a = ""
     a.freeze
-    -> { a.chop! }.should raise_error(frozen_error_class)
+    -> { a.chop! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/chr_spec.rb b/spec/ruby/core/string/chr_spec.rb
index 9ed29542e6..26c7d51202 100644
--- a/spec/ruby/core/string/chr_spec.rb
+++ b/spec/ruby/core/string/chr_spec.rb
@@ -3,11 +3,11 @@ require_relative '../../spec_helper'
 describe "String#chr" do
   it "returns a copy of self" do
     s = 'e'
-    s.should_not equal s.chr
+    s.should_not.equal? s.chr
   end
 
   it "returns a String" do
-    'glark'.chr.should be_an_instance_of(String)
+    'glark'.chr.should.instance_of?(String)
   end
 
   it "returns an empty String if self is an empty String" do
diff --git a/spec/ruby/core/string/clear_spec.rb b/spec/ruby/core/string/clear_spec.rb
index 0b5b8e6998..d4688d3689 100644
--- a/spec/ruby/core/string/clear_spec.rb
+++ b/spec/ruby/core/string/clear_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#clear" do
@@ -13,7 +14,7 @@ describe "String#clear" do
   it "returns self after emptying it" do
     cleared = @s.clear
     cleared.should == ""
-    cleared.should equal @s
+    cleared.should.equal? @s
   end
 
   it "preserves its encoding" do
@@ -29,9 +30,9 @@ describe "String#clear" do
     s.should == ""
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     @s.freeze
-    -> { @s.clear        }.should raise_error(frozen_error_class)
-    -> { "".freeze.clear }.should raise_error(frozen_error_class)
+    -> { @s.clear        }.should.raise(FrozenError)
+    -> { "".freeze.clear }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/clone_spec.rb b/spec/ruby/core/string/clone_spec.rb
index f8d40423f0..2cb289d2c1 100644
--- a/spec/ruby/core/string/clone_spec.rb
+++ b/spec/ruby/core/string/clone_spec.rb
@@ -43,8 +43,8 @@ describe "String#clone" do
   end
 
   it "copies frozen state" do
-    @obj.freeze.clone.frozen?.should be_true
-    "".freeze.clone.frozen?.should be_true
+    @obj.freeze.clone.frozen?.should == true
+    "".freeze.clone.frozen?.should == true
   end
 
   it "does not modify the original string when changing cloned string" do
@@ -54,4 +54,8 @@ describe "String#clone" do
     orig.should == "xtring"
     clone.should == "string"
   end
+
+  it "returns a String in the same encoding as self" do
+    "a".encode("US-ASCII").clone.encoding.should == Encoding::US_ASCII
+  end
 end
diff --git a/spec/ruby/core/string/codepoints_spec.rb b/spec/ruby/core/string/codepoints_spec.rb
index 0b6cde82f7..51bd57d127 100644
--- a/spec/ruby/core/string/codepoints_spec.rb
+++ b/spec/ruby/core/string/codepoints_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'shared/codepoints'
 require_relative 'shared/each_codepoint_without_block'
@@ -11,8 +11,8 @@ describe "String#codepoints" do
   end
 
   it "raises an ArgumentError when no block is given if self has an invalid encoding" do
-    s = "\xDF".force_encoding(Encoding::UTF_8)
-    s.valid_encoding?.should be_false
-    -> { s.codepoints }.should raise_error(ArgumentError)
+    s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.codepoints }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/comparison_spec.rb b/spec/ruby/core/string/comparison_spec.rb
index 01199274b6..0737c131bb 100644
--- a/spec/ruby/core/string/comparison_spec.rb
+++ b/spec/ruby/core/string/comparison_spec.rb
@@ -61,12 +61,12 @@ describe "String#<=> with String" do
   end
 
   it "ignores encoding difference" do
-    ("ÄÖÛ".force_encoding("utf-8") <=> "ÄÖÜ".force_encoding("iso-8859-1")).should == -1
-    ("ÄÖÜ".force_encoding("utf-8") <=> "ÄÖÛ".force_encoding("iso-8859-1")).should == 1
+    ("ÄÖÛ".dup.force_encoding("utf-8") <=> "ÄÖÜ".dup.force_encoding("iso-8859-1")).should == -1
+    ("ÄÖÜ".dup.force_encoding("utf-8") <=> "ÄÖÛ".dup.force_encoding("iso-8859-1")).should == 1
   end
 
   it "returns 0 with identical ASCII-compatible bytes of different encodings" do
-    ("abc".force_encoding("utf-8") <=> "abc".force_encoding("iso-8859-1")).should == 0
+    ("abc".dup.force_encoding("utf-8") <=> "abc".dup.force_encoding("iso-8859-1")).should == 0
   end
 
   it "compares the indices of the encodings when the strings have identical non-ASCII-compatible bytes" do
@@ -75,13 +75,17 @@ describe "String#<=> with String" do
     (xff_1 <=> xff_2).should == -1
     (xff_2 <=> xff_1).should ==  1
   end
+
+  it "returns 0 when comparing 2 empty strings but one is not ASCII-compatible" do
+    ("" <=> "".dup.force_encoding('iso-2022-jp')).should == 0
+  end
 end
 
 # Note: This is inconsistent with Array#<=> which calls #to_ary instead of
 # just using it as an indicator.
 describe "String#<=>" do
   it "returns nil if its argument provides neither #to_str nor #<=>" do
-    ("abc" <=> mock('x')).should be_nil
+    ("abc" <=> mock('x')).should == nil
   end
 
   it "uses the result of calling #to_str for comparison when #to_str is defined" do
@@ -103,6 +107,6 @@ describe "String#<=>" do
     def obj.<=>(other); other <=> self; end
     obj.should_receive(:<=>).once
 
-    ("abc" <=> obj).should be_nil
+    ("abc" <=> obj).should == nil
   end
 end
diff --git a/spec/ruby/core/string/concat_spec.rb b/spec/ruby/core/string/concat_spec.rb
index 5f6daadad7..0194a357a0 100644
--- a/spec/ruby/core/string/concat_spec.rb
+++ b/spec/ruby/core/string/concat_spec.rb
@@ -5,22 +5,23 @@ require_relative 'shared/concat'
 describe "String#concat" do
   it_behaves_like :string_concat, :concat
   it_behaves_like :string_concat_encoding, :concat
+  it_behaves_like :string_concat_type_coercion, :concat
 
   it "takes multiple arguments" do
-    str = "hello "
+    str = +"hello "
     str.concat "wo", "", "rld"
     str.should == "hello world"
   end
 
   it "concatenates the initial value when given arguments contain 2 self" do
-    str = "hello"
+    str = +"hello"
     str.concat str, str
     str.should == "hellohellohello"
   end
 
   it "returns self when given no arguments" do
-    str = "hello"
-    str.concat.should equal(str)
+    str = +"hello"
+    str.concat.should.equal?(str)
     str.should == "hello"
   end
 end
diff --git a/spec/ruby/core/string/count_spec.rb b/spec/ruby/core/string/count_spec.rb
index 06ba5a4f0e..fd127c6ff2 100644
--- a/spec/ruby/core/string/count_spec.rb
+++ b/spec/ruby/core/string/count_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -23,7 +23,7 @@ describe "String#count" do
   end
 
   it "raises an ArgumentError when given no arguments" do
-    -> { "hell yeah".count }.should raise_error(ArgumentError)
+    -> { "hell yeah".count }.should.raise(ArgumentError)
   end
 
   it "negates sets starting with ^" do
@@ -76,8 +76,8 @@ describe "String#count" do
   it "raises if the given sequences are invalid" do
     s = "hel-[()]-lo012^"
 
-    -> { s.count("h-e") }.should raise_error(ArgumentError)
-    -> { s.count("^h-e") }.should raise_error(ArgumentError)
+    -> { s.count("h-e") }.should.raise(ArgumentError)
+    -> { s.count("^h-e") }.should.raise(ArgumentError)
   end
 
   it 'returns the number of occurrences of a multi-byte character' do
@@ -98,8 +98,8 @@ describe "String#count" do
   end
 
   it "raises a TypeError when a set arg can't be converted to a string" do
-    -> { "hello world".count(100)       }.should raise_error(TypeError)
-    -> { "hello world".count([])        }.should raise_error(TypeError)
-    -> { "hello world".count(mock('x')) }.should raise_error(TypeError)
+    -> { "hello world".count(100)       }.should.raise(TypeError)
+    -> { "hello world".count([])        }.should.raise(TypeError)
+    -> { "hello world".count(mock('x')) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/string/crypt_spec.rb b/spec/ruby/core/string/crypt_spec.rb
index 7a0f8835f2..924b4d48cf 100644
--- a/spec/ruby/core/string/crypt_spec.rb
+++ b/spec/ruby/core/string/crypt_spec.rb
@@ -15,7 +15,7 @@ describe "String#crypt" do
     end
 
     it "raises Errno::EINVAL when the salt is shorter than 29 characters" do
-      -> { "mypassword".crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHW") }.should raise_error(Errno::EINVAL)
+      -> { "mypassword".crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHW") }.should.raise(Errno::EINVAL)
     end
 
     it "calls #to_str to converts the salt arg to a String" do
@@ -25,23 +25,10 @@ describe "String#crypt" do
       "mypassword".crypt(obj).should == "$2a$04$0WVaz0pV3jzfZ5G5tpmHWuBQGbkjzgtSc3gJbmdy0GAGMa45MFM2."
     end
 
-    it "taints the result if either salt or self is tainted" do
-      tainted_salt = "$2a$04$0WVaz0pV3jzfZ5G5tpmHWu"
-      tainted_str = "mypassword"
-
-      tainted_salt.taint
-      tainted_str.taint
-
-      "mypassword".crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu").tainted?.should == false
-      tainted_str.crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu").tainted?.should == true
-      "mypassword".crypt(tainted_salt).tainted?.should == true
-      tainted_str.crypt(tainted_salt).tainted?.should == true
-    end
-
     it "doesn't return subclass instances" do
-      StringSpecs::MyString.new("mypassword").crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu").should be_an_instance_of(String)
-      "mypassword".crypt(StringSpecs::MyString.new("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu")).should be_an_instance_of(String)
-      StringSpecs::MyString.new("mypassword").crypt(StringSpecs::MyString.new("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu")).should be_an_instance_of(String)
+      StringSpecs::MyString.new("mypassword").crypt("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu").should.instance_of?(String)
+      "mypassword".crypt(StringSpecs::MyString.new("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu")).should.instance_of?(String)
+      StringSpecs::MyString.new("mypassword").crypt(StringSpecs::MyString.new("$2a$04$0WVaz0pV3jzfZ5G5tpmHWu")).should.instance_of?(String)
     end
   end
 
@@ -73,7 +60,7 @@ describe "String#crypt" do
     end
 
     it "raises an ArgumentError when the string contains NUL character" do
-      -> { "poison\0null".crypt("aa") }.should raise_error(ArgumentError)
+      -> { "poison\0null".crypt("aa") }.should.raise(ArgumentError)
     end
 
     it "calls #to_str to converts the salt arg to a String" do
@@ -83,36 +70,23 @@ describe "String#crypt" do
       "".crypt(obj).should == "aaQSqAReePlq6"
     end
 
-    it "taints the result if either salt or self is tainted" do
-      tainted_salt = "aa"
-      tainted_str = "hello"
-
-      tainted_salt.taint
-      tainted_str.taint
-
-      "hello".crypt("aa").tainted?.should == false
-      tainted_str.crypt("aa").tainted?.should == true
-      "hello".crypt(tainted_salt).tainted?.should == true
-      tainted_str.crypt(tainted_salt).tainted?.should == true
-    end
-
     it "doesn't return subclass instances" do
-      StringSpecs::MyString.new("hello").crypt("aa").should be_an_instance_of(String)
-      "hello".crypt(StringSpecs::MyString.new("aa")).should be_an_instance_of(String)
-      StringSpecs::MyString.new("hello").crypt(StringSpecs::MyString.new("aa")).should be_an_instance_of(String)
+      StringSpecs::MyString.new("hello").crypt("aa").should.instance_of?(String)
+      "hello".crypt(StringSpecs::MyString.new("aa")).should.instance_of?(String)
+      StringSpecs::MyString.new("hello").crypt(StringSpecs::MyString.new("aa")).should.instance_of?(String)
     end
 
     it "raises an ArgumentError when the salt is shorter than two characters" do
-      -> { "hello".crypt("")  }.should raise_error(ArgumentError)
-      -> { "hello".crypt("f") }.should raise_error(ArgumentError)
-      -> { "hello".crypt("\x00\x00") }.should raise_error(ArgumentError)
-      -> { "hello".crypt("\x00a") }.should raise_error(ArgumentError)
-      -> { "hello".crypt("a\x00") }.should raise_error(ArgumentError)
+      -> { "hello".crypt("")  }.should.raise(ArgumentError)
+      -> { "hello".crypt("f") }.should.raise(ArgumentError)
+      -> { "hello".crypt("\x00\x00") }.should.raise(ArgumentError)
+      -> { "hello".crypt("\x00a") }.should.raise(ArgumentError)
+      -> { "hello".crypt("a\x00") }.should.raise(ArgumentError)
     end
   end
 
   it "raises a type error when the salt arg can't be converted to a string" do
-    -> { "".crypt(5)         }.should raise_error(TypeError)
-    -> { "".crypt(mock('x')) }.should raise_error(TypeError)
+    -> { "".crypt(5)         }.should.raise(TypeError)
+    -> { "".crypt(mock('x')) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/string/dedup_spec.rb b/spec/ruby/core/string/dedup_spec.rb
new file mode 100644
index 0000000000..2b31d80708
--- /dev/null
+++ b/spec/ruby/core/string/dedup_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/dedup'
+
+describe 'String#dedup' do
+  it_behaves_like :string_dedup, :dedup
+end
diff --git a/spec/ruby/core/string/delete_prefix_spec.rb b/spec/ruby/core/string/delete_prefix_spec.rb
index b88c503658..fc69adcbad 100644
--- a/spec/ruby/core/string/delete_prefix_spec.rb
+++ b/spec/ruby/core/string/delete_prefix_spec.rb
@@ -1,81 +1,83 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is '2.5' do
-  describe "String#delete_prefix" do
-    it "returns a copy of the string, with the given prefix removed" do
-      'hello'.delete_prefix('hell').should == 'o'
-      'hello'.delete_prefix('hello').should == ''
-    end
+describe "String#delete_prefix" do
+  it "returns a copy of the string, with the given prefix removed" do
+    'hello'.delete_prefix('hell').should == 'o'
+    'hello'.delete_prefix('hello').should == ''
+  end
+
+  it "returns a copy of the string, when the prefix isn't found" do
+    s = 'hello'
+    r = s.delete_prefix('hello!')
+    r.should_not.equal? s
+    r.should == s
+    r = s.delete_prefix('ell')
+    r.should_not.equal? s
+    r.should == s
+    r = s.delete_prefix('')
+    r.should_not.equal? s
+    r.should == s
+  end
 
-    it "returns a copy of the string, when the prefix isn't found" do
-      s = 'hello'
-      r = s.delete_prefix('hello!')
-      r.should_not equal s
-      r.should == s
-      r = s.delete_prefix('ell')
-      r.should_not equal s
-      r.should == s
-      r = s.delete_prefix('')
-      r.should_not equal s
-      r.should == s
-    end
+  it "does not remove partial bytes, only full characters" do
+    "\xe3\x81\x82".delete_prefix("\xe3").should == "\xe3\x81\x82"
+  end
 
-    it "taints resulting strings when other is tainted" do
-      'hello'.taint.delete_prefix('hell').tainted?.should == true
-      'hello'.taint.delete_prefix('').tainted?.should == true
-    end
+  it "doesn't set $~" do
+    $~ = nil
 
-    it "doesn't set $~" do
-      $~ = nil
+    'hello'.delete_prefix('hell')
+    $~.should == nil
+  end
 
-      'hello'.delete_prefix('hell')
-      $~.should == nil
-    end
+  it "calls to_str on its argument" do
+    o = mock('x')
+    o.should_receive(:to_str).and_return 'hell'
+    'hello'.delete_prefix(o).should == 'o'
+  end
 
-    it "calls to_str on its argument" do
-      o = mock('x')
-      o.should_receive(:to_str).and_return 'hell'
-      'hello'.delete_prefix(o).should == 'o'
-    end
+  it "returns a String instance when called on a subclass instance" do
+    s = StringSpecs::MyString.new('hello')
+    s.delete_prefix('hell').should.instance_of?(String)
+  end
 
-    it "returns a subclass instance when called on a subclass instance" do
-      s = StringSpecs::MyString.new('hello')
-      s.delete_prefix('hell').should be_an_instance_of(StringSpecs::MyString)
-    end
+  it "returns a String in the same encoding as self" do
+    'hello'.encode("US-ASCII").delete_prefix('hell').encoding.should == Encoding::US_ASCII
   end
+end
 
-  describe "String#delete_prefix!" do
-    it "removes the found prefix" do
-      s = 'hello'
-      s.delete_prefix!('hell').should equal(s)
-      s.should == 'o'
-    end
+describe "String#delete_prefix!" do
+  it "removes the found prefix" do
+    s = 'hello'
+    s.delete_prefix!('hell').should.equal?(s)
+    s.should == 'o'
+  end
 
-    it "returns nil if no change is made" do
-      s = 'hello'
-      s.delete_prefix!('ell').should == nil
-      s.delete_prefix!('').should == nil
-    end
+  it "returns nil if no change is made" do
+    s = 'hello'
+    s.delete_prefix!('ell').should == nil
+    s.delete_prefix!('').should == nil
+  end
 
-    it "doesn't set $~" do
-      $~ = nil
+  it "doesn't set $~" do
+    $~ = nil
 
-      'hello'.delete_prefix!('hell')
-      $~.should == nil
-    end
+    'hello'.delete_prefix!('hell')
+    $~.should == nil
+  end
 
-    it "calls to_str on its argument" do
-      o = mock('x')
-      o.should_receive(:to_str).and_return 'hell'
-      'hello'.delete_prefix!(o).should == 'o'
-    end
+  it "calls to_str on its argument" do
+    o = mock('x')
+    o.should_receive(:to_str).and_return 'hell'
+    'hello'.delete_prefix!(o).should == 'o'
+  end
 
-    it "raises a #{frozen_error_class} when self is frozen" do
-      -> { 'hello'.freeze.delete_prefix!('hell') }.should raise_error(frozen_error_class)
-      -> { 'hello'.freeze.delete_prefix!('') }.should raise_error(frozen_error_class)
-      -> { ''.freeze.delete_prefix!('') }.should raise_error(frozen_error_class)
-    end
+  it "raises a FrozenError when self is frozen" do
+    -> { 'hello'.freeze.delete_prefix!('hell') }.should.raise(FrozenError)
+    -> { 'hello'.freeze.delete_prefix!('') }.should.raise(FrozenError)
+    -> { ''.freeze.delete_prefix!('') }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/delete_spec.rb b/spec/ruby/core/string/delete_spec.rb
index 6136cd54af..adb5150cff 100644
--- a/spec/ruby/core/string/delete_spec.rb
+++ b/spec/ruby/core/string/delete_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -14,7 +15,7 @@ describe "String#delete" do
   end
 
   it "raises an ArgumentError when given no arguments" do
-    -> { "hell yeah".delete }.should raise_error(ArgumentError)
+    -> { "hell yeah".delete }.should.raise(ArgumentError)
   end
 
   it "negates sets starting with ^" do
@@ -62,17 +63,10 @@ describe "String#delete" do
     not_supported_on :opal do
       xFF = [0xFF].pack('C')
       range = "\x00 - #{xFF}".force_encoding('utf-8')
-      -> { "hello".delete(range).should == "" }.should raise_error(ArgumentError)
+      -> { "hello".delete(range).should == "" }.should.raise(ArgumentError)
     end
-    -> { "hello".delete("h-e") }.should raise_error(ArgumentError)
-    -> { "hello".delete("^h-e") }.should raise_error(ArgumentError)
-  end
-
-  it "taints result when self is tainted" do
-    "hello".taint.delete("e").tainted?.should == true
-    "hello".taint.delete("a-z").tainted?.should == true
-
-    "hello".delete("e".taint).tainted?.should == false
+    -> { "hello".delete("h-e") }.should.raise(ArgumentError)
+    -> { "hello".delete("^h-e") }.should.raise(ArgumentError)
   end
 
   it "tries to convert each set arg to a string using to_str" do
@@ -86,20 +80,24 @@ describe "String#delete" do
   end
 
   it "raises a TypeError when one set arg can't be converted to a string" do
-    -> { "hello world".delete(100)       }.should raise_error(TypeError)
-    -> { "hello world".delete([])        }.should raise_error(TypeError)
-    -> { "hello world".delete(mock('x')) }.should raise_error(TypeError)
+    -> { "hello world".delete(100)       }.should.raise(TypeError)
+    -> { "hello world".delete([])        }.should.raise(TypeError)
+    -> { "hello world".delete(mock('x')) }.should.raise(TypeError)
+  end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("oh no!!!").delete("!").should.instance_of?(String)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("oh no!!!").delete("!").should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String in the same encoding as self" do
+    "hello".encode("US-ASCII").delete("lo").encoding.should == Encoding::US_ASCII
   end
 end
 
 describe "String#delete!" do
   it "modifies self in place and returns self" do
     a = "hello"
-    a.delete!("aeiou", "^e").should equal(a)
+    a.delete!("aeiou", "^e").should.equal?(a)
     a.should == "hell"
   end
 
@@ -109,11 +107,11 @@ describe "String#delete!" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     a = "hello"
     a.freeze
 
-    -> { a.delete!("")            }.should raise_error(frozen_error_class)
-    -> { a.delete!("aeiou", "^e") }.should raise_error(frozen_error_class)
+    -> { a.delete!("")            }.should.raise(FrozenError)
+    -> { a.delete!("aeiou", "^e") }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/delete_suffix_spec.rb b/spec/ruby/core/string/delete_suffix_spec.rb
index 94909cf71d..11d8fbbac1 100644
--- a/spec/ruby/core/string/delete_suffix_spec.rb
+++ b/spec/ruby/core/string/delete_suffix_spec.rb
@@ -1,81 +1,83 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is '2.5' do
-  describe "String#delete_suffix" do
-    it "returns a copy of the string, with the given suffix removed" do
-      'hello'.delete_suffix('ello').should == 'h'
-      'hello'.delete_suffix('hello').should == ''
-    end
+describe "String#delete_suffix" do
+  it "returns a copy of the string, with the given suffix removed" do
+    'hello'.delete_suffix('ello').should == 'h'
+    'hello'.delete_suffix('hello').should == ''
+  end
+
+  it "returns a copy of the string, when the suffix isn't found" do
+    s = 'hello'
+    r = s.delete_suffix('!hello')
+    r.should_not.equal? s
+    r.should == s
+    r = s.delete_suffix('ell')
+    r.should_not.equal? s
+    r.should == s
+    r = s.delete_suffix('')
+    r.should_not.equal? s
+    r.should == s
+  end
 
-    it "returns a copy of the string, when the suffix isn't found" do
-      s = 'hello'
-      r = s.delete_suffix('!hello')
-      r.should_not equal s
-      r.should == s
-      r = s.delete_suffix('ell')
-      r.should_not equal s
-      r.should == s
-      r = s.delete_suffix('')
-      r.should_not equal s
-      r.should == s
-    end
+  it "does not remove partial bytes, only full characters" do
+    "\xe3\x81\x82".delete_suffix("\x82").should == "\xe3\x81\x82"
+  end
 
-    it "taints resulting strings when other is tainted" do
-      'hello'.taint.delete_suffix('ello').tainted?.should == true
-      'hello'.taint.delete_suffix('').tainted?.should == true
-    end
+  it "doesn't set $~" do
+    $~ = nil
 
-    it "doesn't set $~" do
-      $~ = nil
+    'hello'.delete_suffix('ello')
+    $~.should == nil
+  end
 
-      'hello'.delete_suffix('ello')
-      $~.should == nil
-    end
+  it "calls to_str on its argument" do
+    o = mock('x')
+    o.should_receive(:to_str).and_return 'ello'
+    'hello'.delete_suffix(o).should == 'h'
+  end
 
-    it "calls to_str on its argument" do
-      o = mock('x')
-      o.should_receive(:to_str).and_return 'ello'
-      'hello'.delete_suffix(o).should == 'h'
-    end
+  it "returns a String instance when called on a subclass instance" do
+    s = StringSpecs::MyString.new('hello')
+    s.delete_suffix('ello').should.instance_of?(String)
+  end
 
-    it "returns a subclass instance when called on a subclass instance" do
-      s = StringSpecs::MyString.new('hello')
-      s.delete_suffix('ello').should be_an_instance_of(StringSpecs::MyString)
-    end
+  it "returns a String in the same encoding as self" do
+    "hello".encode("US-ASCII").delete_suffix("ello").encoding.should == Encoding::US_ASCII
   end
+end
 
-  describe "String#delete_suffix!" do
-    it "removes the found prefix" do
-      s = 'hello'
-      s.delete_suffix!('ello').should equal(s)
-      s.should == 'h'
-    end
+describe "String#delete_suffix!" do
+  it "removes the found prefix" do
+    s = 'hello'
+    s.delete_suffix!('ello').should.equal?(s)
+    s.should == 'h'
+  end
 
-    it "returns nil if no change is made" do
-      s = 'hello'
-      s.delete_suffix!('ell').should == nil
-      s.delete_suffix!('').should == nil
-    end
+  it "returns nil if no change is made" do
+    s = 'hello'
+    s.delete_suffix!('ell').should == nil
+    s.delete_suffix!('').should == nil
+  end
 
-    it "doesn't set $~" do
-      $~ = nil
+  it "doesn't set $~" do
+    $~ = nil
 
-      'hello'.delete_suffix!('ello')
-      $~.should == nil
-    end
+    'hello'.delete_suffix!('ello')
+    $~.should == nil
+  end
 
-    it "calls to_str on its argument" do
-      o = mock('x')
-      o.should_receive(:to_str).and_return 'ello'
-      'hello'.delete_suffix!(o).should == 'h'
-    end
+  it "calls to_str on its argument" do
+    o = mock('x')
+    o.should_receive(:to_str).and_return 'ello'
+    'hello'.delete_suffix!(o).should == 'h'
+  end
 
-    it "raises a #{frozen_error_class} when self is frozen" do
-      -> { 'hello'.freeze.delete_suffix!('ello') }.should raise_error(frozen_error_class)
-      -> { 'hello'.freeze.delete_suffix!('') }.should raise_error(frozen_error_class)
-      -> { ''.freeze.delete_suffix!('') }.should raise_error(frozen_error_class)
-    end
+  it "raises a FrozenError when self is frozen" do
+    -> { 'hello'.freeze.delete_suffix!('ello') }.should.raise(FrozenError)
+    -> { 'hello'.freeze.delete_suffix!('') }.should.raise(FrozenError)
+    -> { ''.freeze.delete_suffix!('') }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/downcase_spec.rb b/spec/ruby/core/string/downcase_spec.rb
index 31c8f3f446..4f7f44e5d4 100644
--- a/spec/ruby/core/string/downcase_spec.rb
+++ b/spec/ruby/core/string/downcase_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -8,6 +9,10 @@ describe "String#downcase" do
     "hello".downcase.should == "hello"
   end
 
+  it "returns a String in the same encoding as self" do
+    "hELLO".encode("US-ASCII").downcase.encoding.should == Encoding::US_ASCII
+  end
+
   describe "full Unicode case mapping" do
     it "works for all of Unicode with no option" do
       "ÄÖÜ".downcase.should == "äöü"
@@ -19,7 +24,7 @@ describe "String#downcase" do
       downcased.should == "king"
       downcased.size.should == 4
       downcased.bytesize.should == 4
-      downcased.ascii_only?.should be_true
+      downcased.ascii_only?.should == true
     end
   end
 
@@ -27,6 +32,10 @@ describe "String#downcase" do
     it "does not downcase non-ASCII characters" do
       "CÅR".downcase(:ascii).should == "cÅr"
     end
+
+    it "works with substrings" do
+      "prefix TÉ"[-2..-1].downcase(:ascii).should == "tÉ"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -39,7 +48,7 @@ describe "String#downcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "İ".downcase(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { "İ".downcase(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -53,7 +62,7 @@ describe "String#downcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "İS".downcase(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { "İS".downcase(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -65,27 +74,27 @@ describe "String#downcase" do
   end
 
   it "does not allow invalid options" do
-    -> { "ABC".downcase(:invalid_option) }.should raise_error(ArgumentError)
-  end
-
-  it "taints result when self is tainted" do
-    "".taint.downcase.tainted?.should == true
-    "x".taint.downcase.tainted?.should == true
-    "X".taint.downcase.tainted?.should == true
+    -> { "ABC".downcase(:invalid_option) }.should.raise(ArgumentError)
   end
 
-  it "returns a subclass instance for subclasses" do
-    StringSpecs::MyString.new("FOObar").downcase.should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String instance for subclasses" do
+    StringSpecs::MyString.new("FOObar").downcase.should.instance_of?(String)
   end
 end
 
 describe "String#downcase!" do
   it "modifies self in place" do
     a = "HeLlO"
-    a.downcase!.should equal(a)
+    a.downcase!.should.equal?(a)
     a.should == "hello"
   end
 
+  it "modifies self in place for non-ascii-compatible encodings" do
+    a = "HeLlO".encode("utf-16le")
+    a.downcase!
+    a.should == "hello".encode("utf-16le")
+  end
+
   describe "full Unicode case mapping" do
     it "modifies self in place for all of Unicode with no option" do
       a = "ÄÖÜ"
@@ -100,7 +109,7 @@ describe "String#downcase!" do
       downcased.should == "king"
       downcased.size.should == 4
       downcased.bytesize.should == 4
-      downcased.ascii_only?.should be_true
+      downcased.ascii_only?.should == true
     end
   end
 
@@ -110,6 +119,12 @@ describe "String#downcase!" do
       a.downcase!(:ascii)
       a.should == "cÅr"
     end
+
+    it "works for non-ascii-compatible encodings" do
+      a = "ABC".encode("utf-16le")
+      a.downcase!(:ascii)
+      a.should == "abc".encode("utf-16le")
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -126,7 +141,7 @@ describe "String#downcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "İ"; a.downcase!(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "İ"; a.downcase!(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -144,7 +159,7 @@ describe "String#downcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "İS"; a.downcase!(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "İS"; a.downcase!(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -160,7 +175,7 @@ describe "String#downcase!" do
   end
 
   it "does not allow invalid options" do
-    -> { a = "ABC"; a.downcase!(:invalid_option) }.should raise_error(ArgumentError)
+    -> { a = "ABC"; a.downcase!(:invalid_option) }.should.raise(ArgumentError)
   end
 
   it "returns nil if no modifications were made" do
@@ -169,12 +184,12 @@ describe "String#downcase!" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
-    -> { "HeLlo".freeze.downcase! }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.downcase! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError when self is frozen" do
+    -> { "HeLlo".freeze.downcase! }.should.raise(FrozenError)
+    -> { "hello".freeze.downcase! }.should.raise(FrozenError)
   end
 
   it "sets the result String encoding to the source String encoding" do
-    "ABC".downcase.encoding.should equal(Encoding::UTF_8)
+    "ABC".downcase.encoding.should.equal?(Encoding::UTF_8)
   end
 end
diff --git a/spec/ruby/core/string/dump_spec.rb b/spec/ruby/core/string/dump_spec.rb
index 95eb9aa874..176be79db2 100644
--- a/spec/ruby/core/string/dump_spec.rb
+++ b/spec/ruby/core/string/dump_spec.rb
@@ -3,22 +3,12 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "String#dump" do
-  it "taints the result if self is tainted" do
-    "foo".taint.dump.tainted?.should == true
-    "foo\n".taint.dump.tainted?.should == true
-  end
-
-  it "untrusts the result if self is untrusted" do
-    "foo".untrust.dump.untrusted?.should == true
-    "foo\n".untrust.dump.untrusted?.should == true
-  end
-
   it "does not take into account if a string is frozen" do
-    "foo".freeze.dump.frozen?.should == false
+    "foo".freeze.dump.should_not.frozen?
   end
 
-  it "returns a subclass instance" do
-    StringSpecs::MyString.new.dump.should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String instance" do
+    StringSpecs::MyString.new.dump.should.instance_of?(String)
   end
 
   it "wraps string with \"" do
@@ -352,7 +342,7 @@ describe "String#dump" do
     ].should be_computed_by(:dump)
   end
 
-  it "returns a string with multi-byte UTF-8 characters replaced by \\u{} notation with upper-case hex digits" do
+  it "returns a string with multi-byte UTF-8 characters less than or equal 0xFFFF replaced by \\uXXXX notation with upper-case hex digits" do
     [ [0200.chr('utf-8'), '"\u0080"'],
       [0201.chr('utf-8'), '"\u0081"'],
       [0202.chr('utf-8'), '"\u0082"'],
@@ -384,15 +374,21 @@ describe "String#dump" do
       [0235.chr('utf-8'), '"\u009D"'],
       [0236.chr('utf-8'), '"\u009E"'],
       [0237.chr('utf-8'), '"\u009F"'],
+      [0177777.chr('utf-8'), '"\uFFFF"'],
     ].should be_computed_by(:dump)
   end
 
+  it "returns a string with multi-byte UTF-8 characters greater than 0xFFFF replaced by \\u{XXXXXX} notation with upper-case hex digits" do
+    0x10000.chr('utf-8').dump.should == '"\u{10000}"'
+    0x10FFFF.chr('utf-8').dump.should == '"\u{10FFFF}"'
+  end
+
   it "includes .force_encoding(name) if the encoding isn't ASCII compatible" do
     "\u{876}".encode('utf-16be').dump.should.end_with?(".force_encoding(\"UTF-16BE\")")
     "\u{876}".encode('utf-16le').dump.should.end_with?(".force_encoding(\"UTF-16LE\")")
   end
 
-  it "keeps origin encoding" do
+  it "returns a String in the same encoding as self" do
     "foo".encode("ISO-8859-1").dump.encoding.should == Encoding::ISO_8859_1
     "foo".encode('windows-1251').dump.encoding.should == Encoding::Windows_1251
     1.chr.dump.encoding.should == Encoding::US_ASCII
diff --git a/spec/ruby/core/string/dup_spec.rb b/spec/ruby/core/string/dup_spec.rb
index d650788210..e367f7a311 100644
--- a/spec/ruby/core/string/dup_spec.rb
+++ b/spec/ruby/core/string/dup_spec.rb
@@ -21,7 +21,7 @@ describe "String#dup" do
   it "does not copy singleton methods" do
     def @obj.special() :the_one end
     dup = @obj.dup
-    -> { dup.special }.should raise_error(NameError)
+    -> { dup.special }.should.raise(NameError)
   end
 
   it "does not copy modules included in the singleton class" do
@@ -30,7 +30,7 @@ describe "String#dup" do
     end
 
     dup = @obj.dup
-    -> { dup.repr }.should raise_error(NameError)
+    -> { dup.repr }.should.raise(NameError)
   end
 
   it "does not copy constants defined in the singleton class" do
@@ -39,7 +39,7 @@ describe "String#dup" do
     end
 
     dup = @obj.dup
-    -> { class << dup; CLONE; end }.should raise_error(NameError)
+    -> { class << dup; CLONE; end }.should.raise(NameError)
   end
 
   it "does not modify the original string when changing dupped string" do
@@ -49,4 +49,17 @@ describe "String#dup" do
     orig.should == "xtring"
     dup.should == "string"
   end
+
+  it "does not modify the original setbyte-mutated string when changing dupped string" do
+    orig = +"a"
+    orig.setbyte 0, "b".ord
+    copy = orig.dup
+    orig.setbyte 0, "c".ord
+    orig.should == "c"
+    copy.should == "b"
+  end
+
+  it "returns a String in the same encoding as self" do
+    "hello".encode("US-ASCII").dup.encoding.should == Encoding::US_ASCII
+  end
 end
diff --git a/spec/ruby/core/string/each_byte_spec.rb b/spec/ruby/core/string/each_byte_spec.rb
index e04dca807f..1884df416b 100644
--- a/spec/ruby/core/string/each_byte_spec.rb
+++ b/spec/ruby/core/string/each_byte_spec.rb
@@ -9,39 +9,39 @@ describe "String#each_byte" do
   end
 
   it "keeps iterating from the old position (to new string end) when self changes" do
-    r = ""
-    s = "hello world"
+    r = +""
+    s = +"hello world"
     s.each_byte do |c|
       r << c
       s.insert(0, "<>") if r.size < 3
     end
     r.should == "h><>hello world"
 
-    r = ""
-    s = "hello world"
+    r = +""
+    s = +"hello world"
     s.each_byte { |c| s.slice!(-1); r << c }
     r.should == "hello "
 
-    r = ""
-    s = "hello world"
+    r = +""
+    s = +"hello world"
     s.each_byte { |c| s.slice!(0); r << c }
     r.should == "hlowrd"
 
-    r = ""
-    s = "hello world"
+    r = +""
+    s = +"hello world"
     s.each_byte { |c| s.slice!(0..-1); r << c }
     r.should == "h"
   end
 
   it "returns self" do
     s = "hello"
-    (s.each_byte {}).should equal(s)
+    (s.each_byte {}).should.equal?(s)
   end
 
   describe "when no block is given" do
     it "returns an enumerator" do
       enum = "hello".each_byte
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.to_a.should == [104, 101, 108, 108, 111]
     end
 
diff --git a/spec/ruby/core/string/each_char_spec.rb b/spec/ruby/core/string/each_char_spec.rb
index aff98c0a5c..36219f79db 100644
--- a/spec/ruby/core/string/each_char_spec.rb
+++ b/spec/ruby/core/string/each_char_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../spec_helper"
 require_relative 'shared/chars'
 require_relative 'shared/each_char_without_block'
 
diff --git a/spec/ruby/core/string/each_grapheme_cluster_spec.rb b/spec/ruby/core/string/each_grapheme_cluster_spec.rb
index 5367f84887..e1fa4ae67b 100644
--- a/spec/ruby/core/string/each_grapheme_cluster_spec.rb
+++ b/spec/ruby/core/string/each_grapheme_cluster_spec.rb
@@ -1,11 +1,16 @@
+require_relative "../../spec_helper"
 require_relative 'shared/chars'
 require_relative 'shared/grapheme_clusters'
 require_relative 'shared/each_char_without_block'
 
-ruby_version_is "2.5" do
-  describe "String#each_grapheme_cluster" do
-    it_behaves_like :string_chars, :each_grapheme_cluster
-    it_behaves_like :string_grapheme_clusters, :each_grapheme_cluster
-    it_behaves_like :string_each_char_without_block, :each_grapheme_cluster
+describe "String#each_grapheme_cluster" do
+  it_behaves_like :string_chars, :each_grapheme_cluster
+  it_behaves_like :string_grapheme_clusters, :each_grapheme_cluster
+  it_behaves_like :string_each_char_without_block, :each_grapheme_cluster
+
+  it "yields String instances for subclasses" do
+    a = []
+    StringSpecs::MyString.new("abc").each_grapheme_cluster { |s| a << s.class }
+    a.should == [String, String, String]
   end
 end
diff --git a/spec/ruby/core/string/element_set_spec.rb b/spec/ruby/core/string/element_set_spec.rb
index 34e122b055..2abc5117aa 100644
--- a/spec/ruby/core/string/element_set_spec.rb
+++ b/spec/ruby/core/string/element_set_spec.rb
@@ -1,11 +1,12 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 # TODO: Add missing String#[]= specs:
 #   String#[re, idx] = obj
 
-describe "String#[]= with Fixnum index" do
+describe "String#[]= with Integer index" do
   it "replaces the char at idx with other_str" do
     a = "hello"
     a[0] = "bam"
@@ -14,26 +15,16 @@ describe "String#[]= with Fixnum index" do
     a.should == "bamelo"
   end
 
-  it "taints self if other_str is tainted" do
-    a = "hello"
-    a[0] = "".taint
-    a.tainted?.should == true
-
-    a = "hello"
-    a[0] = "x".taint
-    a.tainted?.should == true
-  end
-
   it "raises an IndexError without changing self if idx is outside of self" do
     str = "hello"
 
-    -> { str[20] = "bam" }.should raise_error(IndexError)
+    -> { str[20] = "bam" }.should.raise(IndexError)
     str.should == "hello"
 
-    -> { str[-20] = "bam" }.should raise_error(IndexError)
+    -> { str[-20] = "bam" }.should.raise(IndexError)
     str.should == "hello"
 
-    -> { ""[-1] = "bam" }.should raise_error(IndexError)
+    -> { ""[-1] = "bam" }.should.raise(IndexError)
   end
 
   # Behaviour is verified by matz in
@@ -46,15 +37,15 @@ describe "String#[]= with Fixnum index" do
 
   it "raises IndexError if the string index doesn't match a position in the string" do
     str = "hello"
-    -> { str['y'] = "bam" }.should raise_error(IndexError)
+    -> { str['y'] = "bam" }.should.raise(IndexError)
     str.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     a = "hello"
     a.freeze
 
-    -> { a[0] = "bam" }.should raise_error(frozen_error_class)
+    -> { a[0] = "bam" }.should.raise(FrozenError)
   end
 
   it "calls to_int on index" do
@@ -78,17 +69,17 @@ describe "String#[]= with Fixnum index" do
   end
 
   it "raises a TypeError if other_str can't be converted to a String" do
-    -> { "test"[1] = []        }.should raise_error(TypeError)
-    -> { "test"[1] = mock('x') }.should raise_error(TypeError)
-    -> { "test"[1] = nil       }.should raise_error(TypeError)
+    -> { "test"[1] = []        }.should.raise(TypeError)
+    -> { "test"[1] = mock('x') }.should.raise(TypeError)
+    -> { "test"[1] = nil       }.should.raise(TypeError)
   end
 
-  it "raises a TypeError if passed a Fixnum replacement" do
-    -> { "abc"[1] = 65 }.should raise_error(TypeError)
+  it "raises a TypeError if passed an Integer replacement" do
+    -> { "abc"[1] = 65 }.should.raise(TypeError)
   end
 
   it "raises an IndexError if the index is greater than character size" do
-    -> { "あれ"[4] = "a" }.should raise_error(IndexError)
+    -> { "あれ"[4] = "a" }.should.raise(IndexError)
   end
 
   it "calls #to_int to convert the index" do
@@ -100,18 +91,18 @@ describe "String#[]= with Fixnum index" do
     str.should == "あa"
   end
 
-  it "raises a TypeError if #to_int does not return an Fixnum" do
+  it "raises a TypeError if #to_int does not return an Integer" do
     index = mock("string element set")
     index.should_receive(:to_int).and_return('1')
 
-    -> { "abc"[index] = "d" }.should raise_error(TypeError)
+    -> { "abc"[index] = "d" }.should.raise(TypeError)
   end
 
   it "raises an IndexError if #to_int returns a value out of range" do
     index = mock("string element set")
     index.should_receive(:to_int).and_return(4)
 
-    -> { "ab"[index] = "c" }.should raise_error(IndexError)
+    -> { "ab"[index] = "c" }.should.raise(IndexError)
   end
 
   it "replaces a character with a multibyte character" do
@@ -136,13 +127,19 @@ describe "String#[]= with Fixnum index" do
     str = " ".force_encoding Encoding::US_ASCII
     rep = [160].pack('C').force_encoding Encoding::BINARY
     str[0] = rep
-    str.encoding.should equal(Encoding::BINARY)
+    str.encoding.should.equal?(Encoding::BINARY)
+  end
+
+  it "updates the string to a compatible encoding" do
+    str = "  "
+    str[1] = [0xB9].pack("C*")
+    str.encoding.should == Encoding::ASCII_8BIT
   end
 
   it "raises an Encoding::CompatibilityError if the replacement encoding is incompatible" do
     str = "あれ"
     rep = "が".encode Encoding::EUC_JP
-    -> { str[0] = rep }.should raise_error(Encoding::CompatibilityError)
+    -> { str[0] = rep }.should.raise(Encoding::CompatibilityError)
   end
 end
 
@@ -167,7 +164,7 @@ describe "String#[]= with String index" do
 
   it "raises an IndexError if the search String is not found" do
     str = "abcde"
-    -> { str["g"] = "h" }.should raise_error(IndexError)
+    -> { str["g"] = "h" }.should.raise(IndexError)
   end
 
   it "replaces characters with a multibyte character" do
@@ -192,13 +189,13 @@ describe "String#[]= with String index" do
     str = " ".force_encoding Encoding::US_ASCII
     rep = [160].pack('C').force_encoding Encoding::BINARY
     str[" "] = rep
-    str.encoding.should equal(Encoding::BINARY)
+    str.encoding.should.equal?(Encoding::BINARY)
   end
 
   it "raises an Encoding::CompatibilityError if the replacement encoding is incompatible" do
     str = "あれ"
     rep = "が".encode Encoding::EUC_JP
-    -> { str["れ"] = rep }.should raise_error(Encoding::CompatibilityError)
+    -> { str["れ"] = rep }.should.raise(Encoding::CompatibilityError)
   end
 end
 
@@ -211,7 +208,7 @@ describe "String#[]= with a Regexp index" do
 
   it "raises IndexError if the regexp index doesn't match a position in the string" do
     str = "hello"
-    -> { str[/y/] = "bam" }.should raise_error(IndexError)
+    -> { str[/y/] = "bam" }.should.raise(IndexError)
     str.should == "hello"
   end
 
@@ -228,7 +225,7 @@ describe "String#[]= with a Regexp index" do
     rep = mock("string element set regexp")
     rep.should_not_receive(:to_str)
 
-    -> { "abc"[/def/] = rep }.should raise_error(IndexError)
+    -> { "abc"[/def/] = rep }.should.raise(IndexError)
   end
 
   describe "with 3 arguments" do
@@ -241,11 +238,11 @@ describe "String#[]= with a Regexp index" do
       str.should == "axc"
     end
 
-    it "raises a TypeError if #to_int does not return a Fixnum" do
+    it "raises a TypeError if #to_int does not return an Integer" do
       ref = mock("string element set regexp ref")
       ref.should_receive(:to_int).and_return(nil)
 
-      -> { "abc"[/a(b)/, ref] = "x" }.should raise_error(TypeError)
+      -> { "abc"[/a(b)/, ref] = "x" }.should.raise(TypeError)
     end
 
     it "uses the 2nd of 3 arguments as which capture should be replaced" do
@@ -264,20 +261,20 @@ describe "String#[]= with a Regexp index" do
       rep = mock("string element set regexp")
       rep.should_not_receive(:to_str)
 
-      -> { "abc"[/a(b)/, 2] = rep }.should raise_error(IndexError)
+      -> { "abc"[/a(b)/, 2] = rep }.should.raise(IndexError)
     end
 
     it "raises IndexError if the specified capture isn't available" do
       str = "aaa bbb ccc"
-      -> { str[/a (bbb) c/,  2] = "ddd" }.should raise_error(IndexError)
-      -> { str[/a (bbb) c/, -2] = "ddd" }.should raise_error(IndexError)
+      -> { str[/a (bbb) c/,  2] = "ddd" }.should.raise(IndexError)
+      -> { str[/a (bbb) c/, -2] = "ddd" }.should.raise(IndexError)
     end
 
     describe "when the optional capture does not match" do
       it "raises an IndexError before setting the replacement" do
         str1 = "a b c"
         str2 = str1.dup
-        -> { str2[/a (b) (Z)?/,  2] = "d" }.should raise_error(IndexError)
+        -> { str2[/a (b) (Z)?/,  2] = "d" }.should.raise(IndexError)
         str2.should == str1
       end
     end
@@ -305,13 +302,13 @@ describe "String#[]= with a Regexp index" do
     str = " ".force_encoding Encoding::US_ASCII
     rep = [160].pack('C').force_encoding Encoding::BINARY
     str[/ /] = rep
-    str.encoding.should equal(Encoding::BINARY)
+    str.encoding.should.equal?(Encoding::BINARY)
   end
 
   it "raises an Encoding::CompatibilityError if the replacement encoding is incompatible" do
     str = "あれ"
     rep = "が".encode Encoding::EUC_JP
-    -> { str[/れ/] = rep }.should raise_error(Encoding::CompatibilityError)
+    -> { str[/れ/] = rep }.should.raise(Encoding::CompatibilityError)
   end
 end
 
@@ -361,11 +358,11 @@ describe "String#[]= with a Range index" do
   end
 
   it "raises a RangeError if negative Range begin is out of range" do
-    -> { "abc"[-4..-2] = "x" }.should raise_error(RangeError)
+    -> { "abc"[-4..-2] = "x" }.should.raise(RangeError, "-4..-2 out of range")
   end
 
   it "raises a RangeError if positive Range begin is greater than String size" do
-    -> { "abc"[4..2] = "x" }.should raise_error(RangeError)
+    -> { "abc"[4..2] = "x" }.should.raise(RangeError, "4..2 out of range")
   end
 
   it "uses the Range end as an index rather than a count" do
@@ -426,17 +423,17 @@ describe "String#[]= with a Range index" do
     str = " ".force_encoding Encoding::US_ASCII
     rep = [160].pack('C').force_encoding Encoding::BINARY
     str[0..1] = rep
-    str.encoding.should equal(Encoding::BINARY)
+    str.encoding.should.equal?(Encoding::BINARY)
   end
 
   it "raises an Encoding::CompatibilityError if the replacement encoding is incompatible" do
     str = "あれ"
     rep = "が".encode Encoding::EUC_JP
-    -> { str[0..1] = rep }.should raise_error(Encoding::CompatibilityError)
+    -> { str[0..1] = rep }.should.raise(Encoding::CompatibilityError)
   end
 end
 
-describe "String#[]= with Fixnum index, count" do
+describe "String#[]= with Integer index, count" do
   it "starts at idx and overwrites count characters before inserting the rest of other_str" do
     a = "hello"
     a[0, 2] = "xx"
@@ -485,16 +482,6 @@ describe "String#[]= with Fixnum index, count" do
     a.should == "hellobob"
   end
 
-  it "taints self if other_str is tainted" do
-    a = "hello"
-    a[0, 0] = "".taint
-    a.tainted?.should == true
-
-    a = "hello"
-    a[1, 4] = "x".taint
-    a.tainted?.should == true
-  end
-
   it "calls #to_int to convert the index and count objects" do
     index = mock("string element set index")
     index.should_receive(:to_int).and_return(-4)
@@ -511,14 +498,14 @@ describe "String#[]= with Fixnum index, count" do
     index = mock("string element set index")
     index.should_receive(:to_int).and_return("1")
 
-    -> { "abc"[index, 2] = "xyz" }.should raise_error(TypeError)
+    -> { "abc"[index, 2] = "xyz" }.should.raise(TypeError)
   end
 
   it "raises a TypeError if #to_int for count does not return an Integer" do
     count = mock("string element set count")
     count.should_receive(:to_int).and_return("1")
 
-    -> { "abc"[1, count] = "xyz" }.should raise_error(TypeError)
+    -> { "abc"[1, count] = "xyz" }.should.raise(TypeError)
   end
 
   it "calls #to_str to convert the replacement object" do
@@ -534,23 +521,23 @@ describe "String#[]= with Fixnum index, count" do
     r = mock("string element set replacement")
     r.should_receive(:to_str).and_return(nil)
 
-    -> { "abc"[1, 1] = r }.should raise_error(TypeError)
+    -> { "abc"[1, 1] = r }.should.raise(TypeError)
   end
 
   it "raises an IndexError if |idx| is greater than the length of the string" do
-    -> { "hello"[6, 0] = "bob"  }.should raise_error(IndexError)
-    -> { "hello"[-6, 0] = "bob" }.should raise_error(IndexError)
+    -> { "hello"[6, 0] = "bob"  }.should.raise(IndexError)
+    -> { "hello"[-6, 0] = "bob" }.should.raise(IndexError)
   end
 
   it "raises an IndexError if count < 0" do
-    -> { "hello"[0, -1] = "bob" }.should raise_error(IndexError)
-    -> { "hello"[1, -1] = "bob" }.should raise_error(IndexError)
+    -> { "hello"[0, -1] = "bob" }.should.raise(IndexError)
+    -> { "hello"[1, -1] = "bob" }.should.raise(IndexError)
   end
 
   it "raises a TypeError if other_str is a type other than String" do
-    -> { "hello"[0, 2] = nil  }.should raise_error(TypeError)
-    -> { "hello"[0, 2] = []   }.should raise_error(TypeError)
-    -> { "hello"[0, 2] = 33   }.should raise_error(TypeError)
+    -> { "hello"[0, 2] = nil  }.should.raise(TypeError)
+    -> { "hello"[0, 2] = []   }.should.raise(TypeError)
+    -> { "hello"[0, 2] = 33   }.should.raise(TypeError)
   end
 
   it "replaces characters with a multibyte character" do
@@ -584,19 +571,19 @@ describe "String#[]= with Fixnum index, count" do
   end
 
   it "raises an IndexError if the character index is out of range of a multibyte String" do
-    -> { "あれ"[3, 0] = "り" }.should raise_error(IndexError)
+    -> { "あれ"[3, 0] = "り" }.should.raise(IndexError)
   end
 
   it "encodes the String in an encoding compatible with the replacement" do
     str = " ".force_encoding Encoding::US_ASCII
     rep = [160].pack('C').force_encoding Encoding::BINARY
     str[0, 1] = rep
-    str.encoding.should equal(Encoding::BINARY)
+    str.encoding.should.equal?(Encoding::BINARY)
   end
 
   it "raises an Encoding::CompatibilityError if the replacement encoding is incompatible" do
     str = "あれ"
     rep = "が".encode Encoding::EUC_JP
-    -> { str[0, 1] = rep }.should raise_error(Encoding::CompatibilityError)
+    -> { str[0, 1] = rep }.should.raise(Encoding::CompatibilityError)
   end
 end
diff --git a/spec/ruby/core/string/empty_spec.rb b/spec/ruby/core/string/empty_spec.rb
index fb52070723..8e53a16afc 100644
--- a/spec/ruby/core/string/empty_spec.rb
+++ b/spec/ruby/core/string/empty_spec.rb
@@ -3,10 +3,10 @@ require_relative 'fixtures/classes'
 
 describe "String#empty?" do
   it "returns true if the string has a length of zero" do
-    "hello".empty?.should == false
-    " ".empty?.should == false
-    "\x00".empty?.should == false
-    "".empty?.should == true
-    StringSpecs::MyString.new("").empty?.should == true
+    "hello".should_not.empty?
+    " ".should_not.empty?
+    "\x00".should_not.empty?
+    "".should.empty?
+    StringSpecs::MyString.new("").should.empty?
   end
 end
diff --git a/spec/ruby/core/string/encode_spec.rb b/spec/ruby/core/string/encode_spec.rb
index 1c0c939358..ab096f4041 100644
--- a/spec/ruby/core/string/encode_spec.rb
+++ b/spec/ruby/core/string/encode_spec.rb
@@ -19,31 +19,37 @@ describe "String#encode" do
     it "returns a copy when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
       str = "あ"
-      str.encode.should_not equal(str)
+      encoded = str.encode
+      encoded.should_not.equal?(str)
+      encoded.should == str
     end
 
     it "returns a copy for a ASCII-only String when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
       str = "abc"
-      str.encode.should_not equal(str)
+      encoded = str.encode
+      encoded.should_not.equal?(str)
+      encoded.should == str
     end
 
     it "encodes an ascii substring of a binary string to UTF-8" do
       x82 = [0x82].pack('C')
-      str =  "#{x82}foo".force_encoding("binary")[1..-1].encode("utf-8")
-      str.should == "foo".force_encoding("utf-8")
-      str.encoding.should equal(Encoding::UTF_8)
+      str =  "#{x82}foo".dup.force_encoding("binary")[1..-1].encode("utf-8")
+      str.should == "foo".dup.force_encoding("utf-8")
+      str.encoding.should.equal?(Encoding::UTF_8)
     end
   end
 
   describe "when passed to encoding" do
     it "returns a copy when passed the same encoding as the String" do
       str = "あ"
-      str.encode(Encoding::UTF_8).should_not equal(str)
+      encoded = str.encode(Encoding::UTF_8)
+      encoded.should_not.equal?(str)
+      encoded.should == str
     end
 
     it "round trips a String" do
-      str = "abc def".force_encoding Encoding::US_ASCII
+      str = "abc def".dup.force_encoding Encoding::US_ASCII
       str.encode("utf-32be").encode("ascii").should == "abc def"
     end
   end
@@ -52,29 +58,87 @@ describe "String#encode" do
     it "returns a copy when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
       str = "あ"
-      str.encode(invalid: :replace).should_not equal(str)
+      str.encode(invalid: :replace).should_not.equal?(str)
     end
 
-    it "normalizes newlines" do
-      "\r\nfoo".encode(universal_newline: true).should == "\nfoo"
+    it "normalizes newlines with cr_newline option" do
+      "\r\nfoo".encode(cr_newline: true).should == "\r\rfoo"
+      "\rfoo".encode(cr_newline: true).should == "\rfoo"
+      "\nfoo".encode(cr_newline: true).should == "\rfoo"
+    end
+
+    it "normalizes newlines with crlf_newline option" do
+      "\r\nfoo".encode(crlf_newline: true).should == "\r\r\nfoo"
+      "\rfoo".encode(crlf_newline: true).should == "\rfoo"
+      "\nfoo".encode(crlf_newline: true).should == "\r\nfoo"
+    end
 
+    it "normalizes newlines with universal_newline option" do
+      "\r\nfoo".encode(universal_newline: true).should == "\nfoo"
       "\rfoo".encode(universal_newline: true).should == "\nfoo"
+      "\nfoo".encode(universal_newline: true).should == "\nfoo"
+    end
+
+    it "replaces invalid encoding in source with default replacement" do
+      encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace)
+      encoded.should == "\u3061\ufffd\ufffd".encode("UTF-16LE")
+      encoded.encode("UTF-8").should == "ち\ufffd\ufffd"
+    end
+
+    it "replaces invalid encoding in source with a specified replacement" do
+      encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace, replace: "foo")
+      encoded.should == "\u3061foofoo".encode("UTF-16LE")
+      encoded.encode("UTF-8").should == "ちfoofoo"
+    end
+
+    it "replace multiple invalid bytes at the end with a single replacement character" do
+      "\xE3\x81\x93\xE3\x81".encode("UTF-8", invalid: :replace).should == "\u3053\ufffd"
+    end
+
+    it "replaces invalid encoding in source using a specified replacement even when a fallback is given" do
+      encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace, replace: "foo", fallback: -> c { "bar" })
+      encoded.should == "\u3061foofoo".encode("UTF-16LE")
+      encoded.encode("UTF-8").should == "ちfoofoo"
+    end
+
+    it "replaces undefined encoding in destination with default replacement" do
+      encoded = "B\ufffd".encode(Encoding::US_ASCII, undef: :replace)
+      encoded.should == "B?".encode(Encoding::US_ASCII)
+      encoded.encode("UTF-8").should == "B?"
     end
 
-    it "replaces invalid encoding" do
-      encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace, replace: "?")
-      encoded.should == "\u3061??".encode("UTF-16LE")
-      encoded.encode("UTF-8").should == "ち??"
+    it "replaces undefined encoding in destination with a specified replacement" do
+      encoded = "B\ufffd".encode(Encoding::US_ASCII, undef: :replace, replace: "foo")
+      encoded.should == "Bfoo".encode(Encoding::US_ASCII)
+      encoded.encode("UTF-8").should == "Bfoo"
+    end
+
+    it "replaces undefined encoding in destination with a specified replacement even if a fallback is given" do
+      encoded = "B\ufffd".encode(Encoding::US_ASCII, undef: :replace, replace: "foo", fallback: proc {|x| "bar"})
+      encoded.should == "Bfoo".encode(Encoding::US_ASCII)
+      encoded.encode("UTF-8").should == "Bfoo"
+    end
+
+    it "replaces undefined encoding in destination using a fallback proc" do
+      encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: proc {|x| "bar"})
+      encoded.should == "Bbar".encode(Encoding::US_ASCII)
+      encoded.encode("UTF-8").should == "Bbar"
+    end
+
+    it "replaces invalid encoding in source using replace even when fallback is given as proc" do
+      encoded = "ち\xE3\x81\xFF".encode("UTF-16LE", invalid: :replace, replace: "foo", fallback: proc {|x| "bar"})
+      encoded.should == "\u3061foofoo".encode("UTF-16LE")
+      encoded.encode("UTF-8").should == "ちfoofoo"
     end
   end
 
   describe "when passed to, from" do
     it "returns a copy in the destination encoding when both encodings are the same" do
-      str = "あ"
-      str.force_encoding("binary")
+      str = "あ".dup.force_encoding("binary")
       encoded = str.encode("utf-8", "utf-8")
 
-      encoded.should_not equal(str)
+      encoded.should_not.equal?(str)
+      encoded.should == str.force_encoding("utf-8")
       encoded.encoding.should == Encoding::UTF_8
     end
 
@@ -87,14 +151,27 @@ describe "String#encode" do
   describe "when passed to, options" do
     it "returns a copy when the destination encoding is the same as the String encoding" do
       str = "あ"
-      str.encode(Encoding::UTF_8, undef: :replace).should_not equal(str)
+      encoded = str.encode(Encoding::UTF_8, undef: :replace)
+      encoded.should_not.equal?(str)
+      encoded.should == str
     end
   end
 
   describe "when passed to, from, options" do
     it "returns a copy when both encodings are the same" do
       str = "あ"
-      str.encode("utf-8", "utf-8", invalid: :replace).should_not equal(str)
+      encoded = str.encode("utf-8", "utf-8", invalid: :replace)
+      encoded.should_not.equal?(str)
+      encoded.should == str
+    end
+
+    it "returns a copy in the destination encoding when both encodings are the same" do
+      str = "あ".dup.force_encoding("binary")
+      encoded = str.encode("utf-8", "utf-8", invalid: :replace)
+
+      encoded.should_not.equal?(str)
+      encoded.should == str.force_encoding("utf-8")
+      encoded.encoding.should == Encoding::UTF_8
     end
   end
 end
@@ -112,52 +189,52 @@ describe "String#encode!" do
 
   it_behaves_like :string_encode, :encode!
 
-  it "raises a #{frozen_error_class} when called on a frozen String" do
-    -> { "foo".freeze.encode!("euc-jp") }.should raise_error(frozen_error_class)
+  it "raises a FrozenError when called on a frozen String" do
+    -> { "foo".freeze.encode!("euc-jp") }.should.raise(FrozenError)
   end
 
   # http://redmine.ruby-lang.org/issues/show/1836
-  it "raises a #{frozen_error_class} when called on a frozen String when it's a no-op" do
-    -> { "foo".freeze.encode!("utf-8") }.should raise_error(frozen_error_class)
+  it "raises a FrozenError when called on a frozen String when it's a no-op" do
+    -> { "foo".freeze.encode!("utf-8") }.should.raise(FrozenError)
   end
 
   describe "when passed no options" do
     it "returns self when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "あ"
-      str.encode!.should equal(str)
+      str = +"あ"
+      str.encode!.should.equal?(str)
     end
 
     it "returns self for a ASCII-only String when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "abc"
-      str.encode!.should equal(str)
+      str = +"abc"
+      str.encode!.should.equal?(str)
     end
   end
 
   describe "when passed options" do
     it "returns self for ASCII-only String when Encoding.default_internal is nil" do
       Encoding.default_internal = nil
-      str = "abc"
-      str.encode!(invalid: :replace).should equal(str)
+      str = +"abc"
+      str.encode!(invalid: :replace).should.equal?(str)
     end
   end
 
   describe "when passed to encoding" do
     it "returns self" do
-      str = "abc"
+      str = +"abc"
       result = str.encode!(Encoding::BINARY)
-      result.encoding.should equal(Encoding::BINARY)
-      result.should equal(str)
+      result.encoding.should.equal?(Encoding::BINARY)
+      result.should.equal?(str)
     end
   end
 
   describe "when passed to, from" do
     it "returns self" do
-      str = "ああ"
+      str = +"ああ"
       result = str.encode!("euc-jp", "utf-8")
-      result.encoding.should equal(Encoding::EUC_JP)
-      result.should equal(str)
+      result.encoding.should.equal?(Encoding::EUC_JP)
+      result.should.equal?(str)
     end
   end
 end
diff --git a/spec/ruby/core/string/encoding_spec.rb b/spec/ruby/core/string/encoding_spec.rb
index 4d17a39f29..aa0e4765ed 100644
--- a/spec/ruby/core/string/encoding_spec.rb
+++ b/spec/ruby/core/string/encoding_spec.rb
@@ -4,20 +4,21 @@ require_relative 'fixtures/iso-8859-9-encoding'
 
 describe "String#encoding" do
   it "returns an Encoding object" do
-    String.new.encoding.should be_an_instance_of(Encoding)
+    String.new.encoding.should.instance_of?(Encoding)
   end
 
   it "is equal to the source encoding by default" do
     s = StringSpecs::ISO88599Encoding.new
     s.cedilla.encoding.should == s.source_encoding
+    s.cedilla.encode("utf-8").should == 350.chr(Encoding::UTF_8) # S-cedilla
   end
 
   it "returns the given encoding if #force_encoding has been called" do
-    "a".force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "a".dup.force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
   end
 
   it "returns the given encoding if #encode!has been called" do
-    "a".encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "a".dup.encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
   end
 end
 
@@ -69,13 +70,13 @@ describe "String#encoding for Strings with \\u escapes" do
 
   it "returns US-ASCII if self is US-ASCII only" do
     s = "\u{40}"
-    s.ascii_only?.should be_true
+    s.ascii_only?.should == true
     s.encoding.should == Encoding::US_ASCII
   end
 
   it "returns UTF-8 if self isn't US-ASCII only" do
     s = "\u{4076}\u{619}"
-    s.ascii_only?.should be_false
+    s.ascii_only?.should == false
     s.encoding.should == Encoding::UTF_8
   end
 
@@ -107,13 +108,13 @@ describe "String#encoding for Strings with \\u escapes" do
   end
 
   it "returns the given encoding if #force_encoding has been called" do
-    "\u{20}".force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
-    "\u{2020}".force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "\u{20}".dup.force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "\u{2020}".dup.force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
   end
 
   it "returns the given encoding if #encode!has been called" do
-    "\u{20}".encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
-    "\u{2020}".encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "\u{20}".dup.encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "\u{2020}".dup.encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
   end
 end
 
@@ -121,7 +122,7 @@ describe "String#encoding for Strings with \\x escapes" do
 
   it "returns US-ASCII if self is US-ASCII only" do
     s = "\x61"
-    s.ascii_only?.should be_true
+    s.ascii_only?.should == true
     s.encoding.should == Encoding::US_ASCII
   end
 
@@ -130,7 +131,7 @@ describe "String#encoding for Strings with \\x escapes" do
     str = " "
     str.encoding.should == Encoding::US_ASCII
     str += [0xDF].pack('C')
-    str.ascii_only?.should be_false
+    str.ascii_only?.should == false
     str.encoding.should == Encoding::BINARY
   end
 
@@ -139,7 +140,7 @@ describe "String#encoding for Strings with \\x escapes" do
   it "returns the source encoding when an escape creates a byte with the 8th bit set if the source encoding isn't US-ASCII" do
     fixture  = StringSpecs::ISO88599Encoding.new
     fixture.source_encoding.should == Encoding::ISO8859_9
-    fixture.x_escape.ascii_only?.should be_false
+    fixture.x_escape.ascii_only?.should == false
     fixture.x_escape.encoding.should == Encoding::ISO8859_9
   end
 
@@ -172,16 +173,12 @@ describe "String#encoding for Strings with \\x escapes" do
   end
 
   it "returns the given encoding if #force_encoding has been called" do
-    x50 = "\x50"
-    x50.force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
-    xD4 = [212].pack('C')
-    xD4.force_encoding(Encoding::ISO_8859_9).encoding.should == Encoding::ISO_8859_9
+    "\x50".dup.force_encoding(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    [212].pack('C').force_encoding(Encoding::ISO_8859_9).encoding.should == Encoding::ISO_8859_9
   end
 
   it "returns the given encoding if #encode!has been called" do
-    x50 = "\x50"
-    x50.encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
-    x00 = "x\00"
-    x00.encode!(Encoding::UTF_8).encoding.should == Encoding::UTF_8
+    "\x50".dup.encode!(Encoding::SHIFT_JIS).encoding.should == Encoding::SHIFT_JIS
+    "x\00".dup.encode!(Encoding::UTF_8).encoding.should == Encoding::UTF_8
   end
 end
diff --git a/spec/ruby/core/string/end_with_spec.rb b/spec/ruby/core/string/end_with_spec.rb
index 9ced0ca3d2..ac4fff72ad 100644
--- a/spec/ruby/core/string/end_with_spec.rb
+++ b/spec/ruby/core/string/end_with_spec.rb
@@ -1,56 +1,8 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../shared/string/end_with'
 
 describe "String#end_with?" do
-  it "returns true only if ends match" do
-    s = "hello"
-    s.should.end_with?('o')
-    s.should.end_with?('llo')
-  end
-
-  it 'returns false if the end does not match' do
-    s = 'hello'
-    s.should_not.end_with?('ll')
-  end
-
-  it "returns true if the search string is empty" do
-    "hello".should.end_with?("")
-    "".should.end_with?("")
-  end
-
-  it "returns true only if any ending match" do
-    "hello".should.end_with?('x', 'y', 'llo', 'z')
-  end
-
-  it "converts its argument using :to_str" do
-    s = "hello"
-    find = mock('o')
-    find.should_receive(:to_str).and_return("o")
-    s.should.end_with?(find)
-  end
-
-  it "ignores arguments not convertible to string" do
-    "hello".should_not.end_with?()
-    -> { "hello".end_with?(1) }.should raise_error(TypeError)
-    -> { "hello".end_with?(["o"]) }.should raise_error(TypeError)
-    -> { "hello".end_with?(1, nil, "o") }.should raise_error(TypeError)
-  end
-
-  it "uses only the needed arguments" do
-    find = mock('h')
-    find.should_not_receive(:to_str)
-    "hello".should.end_with?("o",find)
-  end
-
-  it "works for multibyte strings" do
-    "céréale".should.end_with?("réale")
-  end
-
-  it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
-    pat = "ア".encode Encoding::EUC_JP
-    -> do
-      "あれ".end_with?(pat)
-    end.should raise_error(Encoding::CompatibilityError)
-  end
+  it_behaves_like :end_with, :to_s
 end
diff --git a/spec/ruby/core/string/eql_spec.rb b/spec/ruby/core/string/eql_spec.rb
index 397974d9fb..46ebeda509 100644
--- a/spec/ruby/core/string/eql_spec.rb
+++ b/spec/ruby/core/string/eql_spec.rb
@@ -6,16 +6,16 @@ describe "String#eql?" do
 
   describe "when given a non-String" do
     it "returns false" do
-      'hello'.should_not eql(5)
+      'hello'.should_not.eql?(5)
       not_supported_on :opal do
-        'hello'.should_not eql(:hello)
+        'hello'.should_not.eql?(:hello)
       end
-      'hello'.should_not eql(mock('x'))
+      'hello'.should_not.eql?(mock('x'))
     end
 
     it "does not try to call #to_str on the given argument" do
       (obj = mock('x')).should_not_receive(:to_str)
-      'hello'.should_not eql(obj)
+      'hello'.should_not.eql?(obj)
     end
   end
 end
diff --git a/spec/ruby/core/string/fixtures/classes.rb b/spec/ruby/core/string/fixtures/classes.rb
index 1cc7600abb..26fcd51b5d 100644
--- a/spec/ruby/core/string/fixtures/classes.rb
+++ b/spec/ruby/core/string/fixtures/classes.rb
@@ -46,4 +46,15 @@ module StringSpecs
       self.replace(str)
     end
   end
+
+  class SpecialVarProcessor
+    def process(match)
+      if $~ != nil
+        str = $~[0]
+      else
+        str = "unset"
+      end
+      "<#{str}>"
+    end
+  end
 end
diff --git a/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb b/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
index 61a691ff78..cfa91dedc3 100644
--- a/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
+++ b/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
@@ -4,6 +4,6 @@ module StringSpecs
     def source_encoding; __ENCODING__; end
     def x_escape; [0xDF].pack('C').force_encoding("iso-8859-9"); end
     def ascii_only; "glark"; end
-    def cedilla; "Ş"; end
+    def cedilla; "�"; end # S-cedilla
   end
 end
diff --git a/spec/ruby/core/string/fixtures/to_c.rb b/spec/ruby/core/string/fixtures/to_c.rb
new file mode 100644
index 0000000000..7776933263
--- /dev/null
+++ b/spec/ruby/core/string/fixtures/to_c.rb
@@ -0,0 +1,5 @@
+module StringSpecs
+  def self.to_c_method(string)
+    string.to_c
+  end
+end
diff --git a/spec/ruby/core/string/fixtures/utf-8-encoding.rb b/spec/ruby/core/string/fixtures/utf-8-encoding.rb
deleted file mode 100644
index fd243ec522..0000000000
--- a/spec/ruby/core/string/fixtures/utf-8-encoding.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-# -*- encoding: utf-8 -*-
-module StringSpecs
-  class UTF8Encoding
-    def self.source_encoding; __ENCODING__; end
-    def self.egrave; "é"; end
-  end
-end
diff --git a/spec/ruby/core/string/force_encoding_spec.rb b/spec/ruby/core/string/force_encoding_spec.rb
index 56d9b1e9bc..fc6914213f 100644
--- a/spec/ruby/core/string/force_encoding_spec.rb
+++ b/spec/ruby/core/string/force_encoding_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#force_encoding" do
@@ -40,32 +41,32 @@ describe "String#force_encoding" do
     obj = mock("force_encoding")
     obj.should_receive(:to_str).and_return(1)
 
-    -> { "abc".force_encoding(obj) }.should raise_error(TypeError)
+    -> { "abc".force_encoding(obj) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed nil" do
-    -> { "abc".force_encoding(nil) }.should raise_error(TypeError)
+    -> { "abc".force_encoding(nil) }.should.raise(TypeError)
   end
 
   it "returns self" do
     str = "abc"
-    str.force_encoding('utf-8').should equal(str)
+    str.force_encoding('utf-8').should.equal?(str)
   end
 
   it "sets the encoding even if the String contents are invalid in that encoding" do
     str = "\u{9765}"
     str.force_encoding('euc-jp')
     str.encoding.should == Encoding::EUC_JP
-    str.valid_encoding?.should be_false
+    str.valid_encoding?.should == false
   end
 
   it "does not transcode self" do
-    str = "\u{8612}"
+    str = "é"
     str.dup.force_encoding('utf-16le').should_not == str.encode('utf-16le')
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     str = "abcd".freeze
-    -> { str.force_encoding(str.encoding) }.should raise_error(frozen_error_class)
+    -> { str.force_encoding(str.encoding) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/freeze_spec.rb b/spec/ruby/core/string/freeze_spec.rb
index 04d1e9513c..8485e8de21 100644
--- a/spec/ruby/core/string/freeze_spec.rb
+++ b/spec/ruby/core/string/freeze_spec.rb
@@ -1,13 +1,14 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#freeze" do
 
   it "produces the same object whenever called on an instance of a literal in the source" do
-    "abc".freeze.should equal "abc".freeze
+    "abc".freeze.should.equal? "abc".freeze
   end
 
   it "doesn't produce the same object for different instances of literals in the source" do
-    "abc".should_not equal "abc"
+    "abc".should_not.equal? "abc"
   end
 
   it "being a special form doesn't change the value of defined?" do
diff --git a/spec/ruby/core/string/getbyte_spec.rb b/spec/ruby/core/string/getbyte_spec.rb
index 27b7d826ea..d4619dca61 100644
--- a/spec/ruby/core/string/getbyte_spec.rb
+++ b/spec/ruby/core/string/getbyte_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "String#getbyte" do
   it "returns an Integer if given a valid index" do
-    "a".getbyte(0).should be_kind_of(Integer)
+    "a".getbyte(0).should.is_a?(Integer)
   end
 
   it "starts indexing at 0" do
@@ -51,19 +51,19 @@ describe "String#getbyte" do
   end
 
   it "returns nil for out-of-bound indexes" do
-    "g".getbyte(1).should be_nil
+    "g".getbyte(1).should == nil
   end
 
   it "regards the empty String as containing no bytes" do
-    "".getbyte(0).should be_nil
+    "".getbyte(0).should == nil
   end
 
   it "raises an ArgumentError unless given one argument" do
-    -> { "glark".getbyte     }.should raise_error(ArgumentError)
-    -> { "food".getbyte(0,0) }.should raise_error(ArgumentError)
+    -> { "glark".getbyte     }.should.raise(ArgumentError)
+    -> { "food".getbyte(0,0) }.should.raise(ArgumentError)
   end
 
   it "raises a TypeError unless its argument can be coerced into an Integer" do
-    -> { "a".getbyte('a') }.should raise_error(TypeError)
+    -> { "a".getbyte('a') }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/string/grapheme_clusters_spec.rb b/spec/ruby/core/string/grapheme_clusters_spec.rb
index 0cba0e4216..380a245083 100644
--- a/spec/ruby/core/string/grapheme_clusters_spec.rb
+++ b/spec/ruby/core/string/grapheme_clusters_spec.rb
@@ -1,15 +1,14 @@
+require_relative "../../spec_helper"
 require_relative 'shared/chars'
 require_relative 'shared/grapheme_clusters'
 
-ruby_version_is "2.5" do
-  describe "String#grapheme_clusters" do
-    it_behaves_like :string_chars, :grapheme_clusters
-    it_behaves_like :string_grapheme_clusters, :grapheme_clusters
+describe "String#grapheme_clusters" do
+  it_behaves_like :string_chars, :grapheme_clusters
+  it_behaves_like :string_grapheme_clusters, :grapheme_clusters
 
-    it "returns an array when no block given" do
-      string = "ab\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}\u{1F43E}"
-      string.grapheme_clusters.should == ['a', 'b', "\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}", "\u{1F43E}"]
+  it "returns an array when no block given" do
+    string = "ab\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}\u{1F43E}"
+    string.grapheme_clusters.should == ['a', 'b', "\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}", "\u{1F43E}"]
 
-    end
   end
 end
diff --git a/spec/ruby/core/string/gsub_spec.rb b/spec/ruby/core/string/gsub_spec.rb
index cd66a4f875..d0e1c30bd2 100644
--- a/spec/ruby/core/string/gsub_spec.rb
+++ b/spec/ruby/core/string/gsub_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -160,52 +161,12 @@ describe "String#gsub with pattern and replacement" do
 
   it_behaves_like :string_gsub_named_capture, :gsub
 
-  it "taints the result if the original string or replacement is tainted" do
-    hello = "hello"
-    hello_t = "hello"
-    a = "a"
-    a_t = "a"
-    empty = ""
-    empty_t = ""
-
-    hello_t.taint; a_t.taint; empty_t.taint
-
-    hello_t.gsub(/./, a).tainted?.should == true
-    hello_t.gsub(/./, empty).tainted?.should == true
-
-    hello.gsub(/./, a_t).tainted?.should == true
-    hello.gsub(/./, empty_t).tainted?.should == true
-    hello.gsub(//, empty_t).tainted?.should == true
-
-    hello.gsub(//.taint, "foo").tainted?.should == false
-  end
-
   it "handles pattern collapse" do
     str = "こにちわ"
     reg = %r!!
     str.gsub(reg, ".").should == ".こ.に.ち.わ."
   end
 
-  it "untrusts the result if the original string or replacement is untrusted" do
-    hello = "hello"
-    hello_t = "hello"
-    a = "a"
-    a_t = "a"
-    empty = ""
-    empty_t = ""
-
-    hello_t.untrust; a_t.untrust; empty_t.untrust
-
-    hello_t.gsub(/./, a).untrusted?.should == true
-    hello_t.gsub(/./, empty).untrusted?.should == true
-
-    hello.gsub(/./, a_t).untrusted?.should == true
-    hello.gsub(/./, empty_t).untrusted?.should == true
-    hello.gsub(//, empty_t).untrusted?.should == true
-
-    hello.gsub(//.untrust, "foo").untrusted?.should == false
-  end
-
   it "tries to convert pattern to a string using to_str" do
     pattern = mock('.')
     def pattern.to_str() "." end
@@ -214,9 +175,9 @@ describe "String#gsub with pattern and replacement" do
   end
 
   it "raises a TypeError when pattern can't be converted to a string" do
-    -> { "hello".gsub([], "x")            }.should raise_error(TypeError)
-    -> { "hello".gsub(Object.new, "x")    }.should raise_error(TypeError)
-    -> { "hello".gsub(nil, "x")           }.should raise_error(TypeError)
+    -> { "hello".gsub([], "x")            }.should.raise(TypeError)
+    -> { "hello".gsub(Object.new, "x")    }.should.raise(TypeError)
+    -> { "hello".gsub(nil, "x")           }.should.raise(TypeError)
   end
 
   it "tries to convert replacement to a string using to_str" do
@@ -227,20 +188,18 @@ describe "String#gsub with pattern and replacement" do
   end
 
   it "raises a TypeError when replacement can't be converted to a string" do
-    -> { "hello".gsub(/[aeiou]/, [])            }.should raise_error(TypeError)
-    -> { "hello".gsub(/[aeiou]/, Object.new)    }.should raise_error(TypeError)
-    -> { "hello".gsub(/[aeiou]/, nil)           }.should raise_error(TypeError)
+    -> { "hello".gsub(/[aeiou]/, [])            }.should.raise(TypeError)
+    -> { "hello".gsub(/[aeiou]/, Object.new)    }.should.raise(TypeError)
+    -> { "hello".gsub(/[aeiou]/, nil)           }.should.raise(TypeError)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("").gsub(//, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("").gsub(/foo/, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").gsub(/foo/, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").gsub("foo", "").should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("").gsub(//, "").should.instance_of?(String)
+    StringSpecs::MyString.new("").gsub(/foo/, "").should.instance_of?(String)
+    StringSpecs::MyString.new("foo").gsub(/foo/, "").should.instance_of?(String)
+    StringSpecs::MyString.new("foo").gsub("foo", "").should.instance_of?(String)
   end
 
-  # Note: $~ cannot be tested because mspec messes with it
-
   it "sets $~ to MatchData of last match and nil when there's none" do
     'hello.'.gsub('hello', 'x')
     $~[0].should == 'hello'
@@ -254,6 +213,18 @@ describe "String#gsub with pattern and replacement" do
     'hello.'.gsub(/not/, 'x')
     $~.should == nil
   end
+
+  it "handles a pattern in a superset encoding" do
+    result = 'abc'.force_encoding(Encoding::US_ASCII).gsub('é', 'è')
+    result.should == 'abc'
+    result.encoding.should == Encoding::US_ASCII
+  end
+
+  it "handles a pattern in a subset encoding" do
+    result = 'été'.gsub('t'.force_encoding(Encoding::US_ASCII), 'u')
+    result.should == 'éué'
+    result.encoding.should == Encoding::UTF_8
+  end
 end
 
 describe "String#gsub with pattern and Hash" do
@@ -321,27 +292,6 @@ describe "String#gsub with pattern and Hash" do
     repl = '\& \0 \1 \` \\\' \+ \\\\ foo'
     "hello".gsub(/(.+)/, 'hello' => repl ).should == repl
   end
-
-  it "untrusts the result if the original string is untrusted" do
-    str = "Ghana".untrust
-    str.gsub(/[Aa]na/, 'ana' => '').untrusted?.should be_true
-  end
-
-  it "untrusts the result if a hash value is untrusted" do
-    str = "Ghana"
-    str.gsub(/a$/, 'a' => 'di'.untrust).untrusted?.should be_true
-  end
-
-  it "taints the result if the original string is tainted" do
-    str = "Ghana".taint
-    str.gsub(/[Aa]na/, 'ana' => '').tainted?.should be_true
-  end
-
-  it "taints the result if a hash value is tainted" do
-    str = "Ghana"
-    str.gsub(/a$/, 'a' => 'di'.taint).tainted?.should be_true
-  end
-
 end
 
 describe "String#gsub! with pattern and Hash" do
@@ -410,27 +360,6 @@ describe "String#gsub! with pattern and Hash" do
     repl = '\& \0 \1 \` \\\' \+ \\\\ foo'
     "hello".gsub!(/(.+)/, 'hello' => repl ).should == repl
   end
-
-  it "keeps untrusted state" do
-    str = "Ghana".untrust
-    str.gsub!(/[Aa]na/, 'ana' => '').untrusted?.should be_true
-  end
-
-  it "untrusts self if a hash value is untrusted" do
-    str = "Ghana"
-    str.gsub!(/a$/, 'a' => 'di'.untrust).untrusted?.should be_true
-  end
-
-  it "keeps tainted state" do
-    str = "Ghana".taint
-    str.gsub!(/[Aa]na/, 'ana' => '').tainted?.should be_true
-  end
-
-  it "taints self if a hash value is tainted" do
-    str = "Ghana"
-    str.gsub!(/a$/, 'a' => 'di'.taint).tainted?.should be_true
-  end
-
 end
 
 describe "String#gsub with pattern and block" do
@@ -458,6 +387,11 @@ describe "String#gsub with pattern and block" do
     offsets.should == [[1, 2], [4, 5]]
   end
 
+  it "does not set $~ for procs created from methods" do
+    str = "hello"
+    str.gsub("l", &StringSpecs::SpecialVarProcessor.new.method(:process)).should == "he<unset><unset>o"
+  end
+
   it "restores $~ after leaving the block" do
     [/./, "l"].each do |pattern|
       old_md = nil
@@ -504,26 +438,6 @@ describe "String#gsub with pattern and block" do
     "hello".gsub(/.+/) { obj }.should == "ok"
   end
 
-  it "untrusts the result if the original string or replacement is untrusted" do
-    hello = "hello"
-    hello_t = "hello"
-    a = "a"
-    a_t = "a"
-    empty = ""
-    empty_t = ""
-
-    hello_t.untrust; a_t.untrust; empty_t.untrust
-
-    hello_t.gsub(/./) { a }.untrusted?.should == true
-    hello_t.gsub(/./) { empty }.untrusted?.should == true
-
-    hello.gsub(/./) { a_t }.untrusted?.should == true
-    hello.gsub(/./) { empty_t }.untrusted?.should == true
-    hello.gsub(//) { empty_t }.untrusted?.should == true
-
-    hello.gsub(//.untrust) { "foo" }.untrusted?.should == false
-  end
-
   it "uses the compatible encoding if they are compatible" do
     s  = "hello"
     s2 = "#{195.chr}#{192.chr}#{195.chr}"
@@ -536,8 +450,8 @@ describe "String#gsub with pattern and block" do
     s = "hllëllo"
     s2 = "hellö"
 
-    -> { s.gsub(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should raise_error(Encoding::CompatibilityError)
-    -> { s2.gsub(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should raise_error(Encoding::CompatibilityError)
+    -> { s.gsub(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should.raise(Encoding::CompatibilityError)
+    -> { s2.gsub(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should.raise(Encoding::CompatibilityError)
   end
 
   it "replaces the incompatible part properly even if the encodings are not compatible" do
@@ -549,7 +463,7 @@ describe "String#gsub with pattern and block" do
   not_supported_on :opal do
     it "raises an ArgumentError if encoding is not valid" do
       x92 = [0x92].pack('C').force_encoding('utf-8')
-      -> { "a#{x92}b".gsub(/[^\x00-\x7f]/u, '') }.should raise_error(ArgumentError)
+      -> { "a#{x92}b".gsub(/[^\x00-\x7f]/u, '') }.should.raise(ArgumentError)
     end
   end
 end
@@ -557,7 +471,7 @@ end
 describe "String#gsub with pattern and without replacement and block" do
   it "returns an enumerator" do
     enum = "abca".gsub(/a/)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == ["a", "a"]
   end
 
@@ -570,31 +484,27 @@ describe "String#gsub with pattern and without replacement and block" do
   end
 end
 
+describe "String#gsub with a string pattern" do
+  it "handles multibyte characters" do
+    "é".gsub("é", "â").should == "â"
+    "aé".gsub("é", "â").should == "aâ"
+    "éa".gsub("é", "â").should == "âa"
+  end
+end
+
 describe "String#gsub! with pattern and replacement" do
   it "modifies self in place and returns self" do
     a = "hello"
-    a.gsub!(/[aeiou]/, '*').should equal(a)
+    a.gsub!(/[aeiou]/, '*').should.equal?(a)
     a.should == "h*ll*"
   end
 
   it "modifies self in place with multi-byte characters and returns self" do
     a = "¿por qué?"
-    a.gsub!(/([a-z\d]*)/, "*").should equal(a)
+    a.gsub!(/([a-z\d]*)/, "*").should.equal?(a)
     a.should == "*¿** **é*?*"
   end
 
-  it "taints self if replacement is tainted" do
-    a = "hello"
-    a.gsub!(/./.taint, "foo").tainted?.should == false
-    a.gsub!(/./, "foo".taint).tainted?.should == true
-  end
-
-  it "untrusts self if replacement is untrusted" do
-    a = "hello"
-    a.gsub!(/./.untrust, "foo").untrusted?.should == false
-    a.gsub!(/./, "foo".untrust).untrusted?.should == true
-  end
-
   it "returns nil if no modifications were made" do
     a = "hello"
     a.gsub!(/z/, '*').should == nil
@@ -603,33 +513,42 @@ describe "String#gsub! with pattern and replacement" do
   end
 
   # See [ruby-core:23666]
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     s = "hello"
     s.freeze
 
-    -> { s.gsub!(/ROAR/, "x")    }.should raise_error(frozen_error_class)
-    -> { s.gsub!(/e/, "e")       }.should raise_error(frozen_error_class)
-    -> { s.gsub!(/[aeiou]/, '*') }.should raise_error(frozen_error_class)
+    -> { s.gsub!(/ROAR/, "x")    }.should.raise(FrozenError)
+    -> { s.gsub!(/e/, "e")       }.should.raise(FrozenError)
+    -> { s.gsub!(/[aeiou]/, '*') }.should.raise(FrozenError)
   end
-end
 
-describe "String#gsub! with pattern and block" do
-  it "modifies self in place and returns self" do
-    a = "hello"
-    a.gsub!(/[aeiou]/) { '*' }.should equal(a)
-    a.should == "h*ll*"
+  it "handles a pattern in a superset encoding" do
+    string = 'abc'.force_encoding(Encoding::US_ASCII)
+
+    result = string.gsub!('é', 'è')
+
+    result.should == nil
+    string.should == 'abc'
+    string.encoding.should == Encoding::US_ASCII
   end
 
-  it "taints self if block's result is tainted" do
-    a = "hello"
-    a.gsub!(/./.taint) { "foo" }.tainted?.should == false
-    a.gsub!(/./) { "foo".taint }.tainted?.should == true
+  it "handles a pattern in a subset encoding" do
+    string = 'été'
+    pattern = 't'.force_encoding(Encoding::US_ASCII)
+
+    result = string.gsub!(pattern, 'u')
+
+    result.should == string
+    string.should == 'éué'
+    string.encoding.should == Encoding::UTF_8
   end
+end
 
-  it "untrusts self if block's result is untrusted" do
+describe "String#gsub! with pattern and block" do
+  it "modifies self in place and returns self" do
     a = "hello"
-    a.gsub!(/./.untrust) { "foo" }.untrusted?.should == false
-    a.gsub!(/./) { "foo".untrust }.untrusted?.should == true
+    a.gsub!(/[aeiou]/) { '*' }.should.equal?(a)
+    a.should == "h*ll*"
   end
 
   it "returns nil if no modifications were made" do
@@ -640,13 +559,13 @@ describe "String#gsub! with pattern and block" do
   end
 
   # See [ruby-core:23663]
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     s = "hello"
     s.freeze
 
-    -> { s.gsub!(/ROAR/)    { "x" } }.should raise_error(frozen_error_class)
-    -> { s.gsub!(/e/)       { "e" } }.should raise_error(frozen_error_class)
-    -> { s.gsub!(/[aeiou]/) { '*' } }.should raise_error(frozen_error_class)
+    -> { s.gsub!(/ROAR/)    { "x" } }.should.raise(FrozenError)
+    -> { s.gsub!(/e/)       { "e" } }.should.raise(FrozenError)
+    -> { s.gsub!(/[aeiou]/) { '*' } }.should.raise(FrozenError)
   end
 
   it "uses the compatible encoding if they are compatible" do
@@ -661,8 +580,8 @@ describe "String#gsub! with pattern and block" do
     s = "hllëllo"
     s2 = "hellö"
 
-    -> { s.gsub!(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should raise_error(Encoding::CompatibilityError)
-    -> { s2.gsub!(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should raise_error(Encoding::CompatibilityError)
+    -> { s.gsub!(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should.raise(Encoding::CompatibilityError)
+    -> { s2.gsub!(/l/) { |bar| "Русский".force_encoding("iso-8859-5") } }.should.raise(Encoding::CompatibilityError)
   end
 
   it "replaces the incompatible part properly even if the encodings are not compatible" do
@@ -674,7 +593,7 @@ describe "String#gsub! with pattern and block" do
   not_supported_on :opal do
     it "raises an ArgumentError if encoding is not valid" do
       x92 = [0x92].pack('C').force_encoding('utf-8')
-      -> { "a#{x92}b".gsub!(/[^\x00-\x7f]/u, '') }.should raise_error(ArgumentError)
+      -> { "a#{x92}b".gsub!(/[^\x00-\x7f]/u, '') }.should.raise(ArgumentError)
     end
   end
 end
@@ -682,7 +601,7 @@ end
 describe "String#gsub! with pattern and without replacement and block" do
   it "returns an enumerator" do
     enum = "abca".gsub!(/a/)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == ["a", "a"]
   end
 
diff --git a/spec/ruby/core/string/include_spec.rb b/spec/ruby/core/string/include_spec.rb
index e32eb17c29..d943430335 100644
--- a/spec/ruby/core/string/include_spec.rb
+++ b/spec/ruby/core/string/include_spec.rb
@@ -13,6 +13,20 @@ describe "String#include? with String" do
     StringSpecs::MyString.new("hello").include?(StringSpecs::MyString.new("lo")).should == true
   end
 
+  it "returns true if both strings are empty" do
+    "".should.include?("")
+    "".dup.force_encoding("EUC-JP").should.include?("")
+    "".should.include?("".dup.force_encoding("EUC-JP"))
+    "".dup.force_encoding("EUC-JP").should.include?("".dup.force_encoding("EUC-JP"))
+  end
+
+  it "returns true if the RHS is empty" do
+    "a".should.include?("")
+    "a".dup.force_encoding("EUC-JP").should.include?("")
+    "a".should.include?("".dup.force_encoding("EUC-JP"))
+    "a".dup.force_encoding("EUC-JP").should.include?("".dup.force_encoding("EUC-JP"))
+  end
+
   it "tries to convert other to string using to_str" do
     other = mock('lo')
     other.should_receive(:to_str).and_return("lo")
@@ -21,15 +35,15 @@ describe "String#include? with String" do
   end
 
   it "raises a TypeError if other can't be converted to string" do
-    -> { "hello".include?([])       }.should raise_error(TypeError)
-    -> { "hello".include?('h'.ord)  }.should raise_error(TypeError)
-    -> { "hello".include?(mock('x')) }.should raise_error(TypeError)
+    -> { "hello".include?([])       }.should.raise(TypeError)
+    -> { "hello".include?('h'.ord)  }.should.raise(TypeError)
+    -> { "hello".include?(mock('x')) }.should.raise(TypeError)
   end
 
   it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
     pat = "ア".encode Encoding::EUC_JP
     -> do
       "あれ".include?(pat)
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError)
   end
 end
diff --git a/spec/ruby/core/string/index_spec.rb b/spec/ruby/core/string/index_spec.rb
index ca62911db0..3f82181b98 100644
--- a/spec/ruby/core/string/index_spec.rb
+++ b/spec/ruby/core/string/index_spec.rb
@@ -4,15 +4,15 @@ require_relative 'fixtures/classes'
 
 describe "String#index" do
   it "raises a TypeError if passed nil" do
-    -> { "abc".index nil }.should raise_error(TypeError)
+    -> { "abc".index nil }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed a boolean" do
-    -> { "abc".index true }.should raise_error(TypeError)
+    -> { "abc".index true }.should.raise(TypeError)
   end
 
   it "raises a TypeError if passed a Symbol" do
-    -> { "abc".index :a }.should raise_error(TypeError)
+    -> { "abc".index :a }.should.raise(TypeError)
   end
 
   it "calls #to_str to convert the first argument" do
@@ -27,8 +27,8 @@ describe "String#index" do
     "abc".index("c", offset).should == 2
   end
 
-  it "raises a TypeError if passed a Fixnum" do
-    -> { "abc".index 97 }.should raise_error(TypeError)
+  it "raises a TypeError if passed an Integer" do
+    -> { "abc".index 97 }.should.raise(TypeError)
   end
 end
 
@@ -146,6 +146,7 @@ describe "String#index with String" do
 
   it "returns the character index after offset" do
     "われわれ".index("わ", 1).should == 2
+    "ありがとうありがとう".index("が", 3).should == 7
   end
 
   it "returns the character index after a partial first match" do
@@ -156,7 +157,22 @@ describe "String#index with String" do
     char = "れ".encode Encoding::EUC_JP
     -> do
       "あれ".index char
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "handles a substring in a superset encoding" do
+    'abc'.dup.force_encoding(Encoding::US_ASCII).index('é').should == nil
+  end
+
+  it "handles a substring in a subset encoding" do
+    'été'.index('t'.dup.force_encoding(Encoding::US_ASCII)).should == 1
+  end
+
+  it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
+    str = 'abc'.dup.force_encoding("ISO-2022-JP")
+    pattern = 'b'.dup.force_encoding("EUC-JP")
+
+    -> { str.index(pattern) }.should.raise(Encoding::CompatibilityError, "incompatible character encodings: ISO-2022-JP and EUC-JP")
   end
 end
 
@@ -215,6 +231,15 @@ describe "String#index with Regexp" do
     $~.should == nil
   end
 
+  it "always clear $~" do
+    "a".index(/a/)
+    $~.should_not == nil
+
+    string = "blablabla"
+    string.index(/bla/, string.length + 1)
+    $~.should == nil
+  end
+
   it "starts the search at the given offset" do
     "blablabla".index(/.{0}/, 5).should == 5
     "blablabla".index(/.{1}/, 5).should == 5
@@ -262,7 +287,7 @@ describe "String#index with Regexp" do
   end
 
   it "returns nil if the Regexp matches the empty string and the offset is out of range" do
-    "ruby".index(//,12).should be_nil
+    "ruby".index(//,12).should == nil
   end
 
   it "supports \\G which matches at the given start offset" do
@@ -307,6 +332,6 @@ describe "String#index with Regexp" do
     re = Regexp.new "れ".encode(Encoding::EUC_JP)
     -> do
       "あれ".index re
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError, "incompatible encoding regexp match (EUC-JP regexp with UTF-8 string)")
   end
 end
diff --git a/spec/ruby/core/string/initialize_spec.rb b/spec/ruby/core/string/initialize_spec.rb
index 08734cc916..b0c1e2e573 100644
--- a/spec/ruby/core/string/initialize_spec.rb
+++ b/spec/ruby/core/string/initialize_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/replace'
 
 describe "String#initialize" do
   it "is a private method" do
-    String.should have_private_instance_method(:initialize)
+    String.private_instance_methods(false).should.include?(:initialize)
   end
 
   describe "with no arguments" do
@@ -16,7 +16,7 @@ describe "String#initialize" do
 
     it "does not raise an exception when frozen" do
       a = "hello".freeze
-      a.send(:initialize).should equal(a)
+      a.send(:initialize).should.equal?(a)
     end
   end
 
diff --git a/spec/ruby/core/string/insert_spec.rb b/spec/ruby/core/string/insert_spec.rb
index 588b8ab272..c89793a8ca 100644
--- a/spec/ruby/core/string/insert_spec.rb
+++ b/spec/ruby/core/string/insert_spec.rb
@@ -1,5 +1,5 @@
 # -*- encoding: utf-8 -*-
-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -23,8 +23,8 @@ describe "String#insert with index, other" do
   end
 
   it "raises an IndexError if the index is beyond string" do
-    -> { "abcd".insert(5, 'X')  }.should raise_error(IndexError)
-    -> { "abcd".insert(-6, 'X') }.should raise_error(IndexError)
+    -> { "abcd".insert(5, 'X')  }.should.raise(IndexError)
+    -> { "abcd".insert(-6, 'X') }.should.raise(IndexError)
   end
 
   it "converts index to an integer using to_int" do
@@ -41,26 +41,16 @@ describe "String#insert with index, other" do
     "abcd".insert(-3, other).should == "abXYZcd"
   end
 
-  it "taints self if string to insert is tainted" do
-    str = "abcd"
-    str.insert(0, "T".taint).tainted?.should == true
-
-    str = "abcd"
-    other = mock('T')
-    def other.to_str() "T".taint end
-    str.insert(0, other).tainted?.should == true
-  end
-
   it "raises a TypeError if other can't be converted to string" do
-    -> { "abcd".insert(-6, Object.new)}.should raise_error(TypeError)
-    -> { "abcd".insert(-6, [])        }.should raise_error(TypeError)
-    -> { "abcd".insert(-6, mock('x')) }.should raise_error(TypeError)
+    -> { "abcd".insert(-6, Object.new)}.should.raise(TypeError)
+    -> { "abcd".insert(-6, [])        }.should.raise(TypeError)
+    -> { "abcd".insert(-6, mock('x')) }.should.raise(TypeError)
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     str = "abcd".freeze
-    -> { str.insert(4, '')  }.should raise_error(frozen_error_class)
-    -> { str.insert(4, 'X') }.should raise_error(frozen_error_class)
+    -> { str.insert(4, '')  }.should.raise(FrozenError)
+    -> { str.insert(4, 'X') }.should.raise(FrozenError)
   end
 
   it "inserts a character into a multibyte encoded string" do
@@ -77,6 +67,15 @@ describe "String#insert with index, other" do
     pat = "ア".encode Encoding::EUC_JP
     -> do
       "あれ".insert 0, pat
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "should not call subclassed string methods" do
+    cls = Class.new(String) do
+      def replace(arg)
+        raise "should not call replace"
+      end
+    end
+    cls.new("abcd").insert(0, 'X').should == "Xabcd"
   end
 end
diff --git a/spec/ruby/core/string/inspect_spec.rb b/spec/ruby/core/string/inspect_spec.rb
index c1674c73c8..8b91ce2f84 100644
--- a/spec/ruby/core/string/inspect_spec.rb
+++ b/spec/ruby/core/string/inspect_spec.rb
@@ -3,18 +3,8 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "String#inspect" do
-  it "taints the result if self is tainted" do
-    "foo".taint.inspect.tainted?.should == true
-    "foo\n".taint.inspect.tainted?.should == true
-  end
-
-  it "untrusts the result if self is untrusted" do
-    "foo".untrust.inspect.untrusted?.should == true
-    "foo\n".untrust.inspect.untrusted?.should == true
-  end
-
   it "does not return a subclass instance" do
-    StringSpecs::MyString.new.inspect.should be_an_instance_of(String)
+    StringSpecs::MyString.new.inspect.should.instance_of?(String)
   end
 
   it "returns a string with special characters replaced with \\<char> notation" do
@@ -29,6 +19,21 @@ describe "String#inspect" do
     ].should be_computed_by(:inspect)
   end
 
+  it "returns a string with special characters replaced with \\<char> notation for UTF-16" do
+    pairs = [
+      ["\a", '"\\a"'],
+      ["\b", '"\\b"'],
+      ["\t", '"\\t"'],
+      ["\n", '"\\n"'],
+      ["\v", '"\\v"'],
+      ["\f", '"\\f"'],
+      ["\r", '"\\r"'],
+      ["\e", '"\\e"']
+    ].map { |str, result| [str.encode('UTF-16LE'), result] }
+
+    pairs.should be_computed_by(:inspect)
+  end
+
   it "returns a string with \" and \\ escaped with a backslash" do
     [ ["\"", '"\\""'],
       ["\\", '"\\\\"']
@@ -317,6 +322,15 @@ describe "String#inspect" do
     0.chr.inspect.should == '"\\x00"'
   end
 
+  it "uses \\x notation for broken UTF-8 sequences" do
+    "\xF0\x9F".inspect.should == '"\\xF0\\x9F"'
+  end
+
+  it "works for broken US-ASCII strings" do
+    s = "©".dup.force_encoding("US-ASCII")
+    s.inspect.should == '"\xC2\xA9"'
+  end
+
   describe "when default external is UTF-8" do
     before :each do
       @extenc, Encoding.default_external = Encoding.default_external, Encoding::UTF_8
@@ -496,5 +510,11 @@ describe "String#inspect" do
         "\u{3042}".encode("EUC-JP").inspect.should == '"\\x{A4A2}"'
       end
     end
+
+    describe "and the string has both ASCII-compatible and ASCII-incompatible chars" do
+      it "returns a string with the non-ASCII characters replaced by \\u notation" do
+        "hello привет".encode("utf-16le").inspect.should == '"hello \\u043F\\u0440\\u0438\\u0432\\u0435\\u0442"'
+      end
+    end
   end
 end
diff --git a/spec/ruby/core/string/lines_spec.rb b/spec/ruby/core/string/lines_spec.rb
index ad4b119074..40ab5f71d8 100644
--- a/spec/ruby/core/string/lines_spec.rb
+++ b/spec/ruby/core/string/lines_spec.rb
@@ -1,7 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/each_line'
-require_relative 'shared/each_line_without_block'
 
 describe "String#lines" do
   it_behaves_like :string_each_line, :lines
diff --git a/spec/ruby/core/string/ljust_spec.rb b/spec/ruby/core/string/ljust_spec.rb
index ed4cb86859..0b2aab2638 100644
--- a/spec/ruby/core/string/ljust_spec.rb
+++ b/spec/ruby/core/string/ljust_spec.rb
@@ -31,14 +31,6 @@ describe "String#ljust with length, padding" do
     "radiology".ljust(8, '-').should == "radiology"
   end
 
-  it "taints result when self or padstr is tainted" do
-    "x".taint.ljust(4).tainted?.should == true
-    "x".taint.ljust(0).tainted?.should == true
-    "".taint.ljust(0).tainted?.should == true
-    "x".taint.ljust(4, "*").tainted?.should == true
-    "x".ljust(4, "*".taint).tainted?.should == true
-  end
-
   it "tries to convert length to an integer using to_int" do
     "^".ljust(3.8, "_^").should == "^_^"
 
@@ -49,10 +41,10 @@ describe "String#ljust with length, padding" do
   end
 
   it "raises a TypeError when length can't be converted to an integer" do
-    -> { "hello".ljust("x")       }.should raise_error(TypeError)
-    -> { "hello".ljust("x", "y")  }.should raise_error(TypeError)
-    -> { "hello".ljust([])        }.should raise_error(TypeError)
-    -> { "hello".ljust(mock('x')) }.should raise_error(TypeError)
+    -> { "hello".ljust("x")       }.should.raise(TypeError)
+    -> { "hello".ljust("x", "y")  }.should.raise(TypeError)
+    -> { "hello".ljust([])        }.should.raise(TypeError)
+    -> { "hello".ljust(mock('x')) }.should.raise(TypeError)
   end
 
   it "tries to convert padstr to a string using to_str" do
@@ -63,52 +55,46 @@ describe "String#ljust with length, padding" do
   end
 
   it "raises a TypeError when padstr can't be converted" do
-    -> { "hello".ljust(20, [])        }.should raise_error(TypeError)
-    -> { "hello".ljust(20, Object.new)}.should raise_error(TypeError)
-    -> { "hello".ljust(20, mock('x')) }.should raise_error(TypeError)
+    -> { "hello".ljust(20, [])        }.should.raise(TypeError)
+    -> { "hello".ljust(20, Object.new)}.should.raise(TypeError)
+    -> { "hello".ljust(20, mock('x')) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when padstr is empty" do
-    -> { "hello".ljust(10, '') }.should raise_error(ArgumentError)
+    -> { "hello".ljust(10, '') }.should.raise(ArgumentError)
   end
 
-  it "returns subclass instances when called on subclasses" do
-    StringSpecs::MyString.new("").ljust(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").ljust(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").ljust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(StringSpecs::MyString)
-
-    "".ljust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-    "foo".ljust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-  end
+  it "returns String instances when called on subclasses" do
+    StringSpecs::MyString.new("").ljust(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").ljust(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").ljust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
 
-  it "when padding is tainted and self is untainted returns a tainted string if and only if length is longer than self" do
-    "hello".ljust(4, 'X'.taint).tainted?.should be_false
-    "hello".ljust(5, 'X'.taint).tainted?.should be_false
-    "hello".ljust(6, 'X'.taint).tainted?.should be_true
+    "".ljust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
+    "foo".ljust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
   end
 
   describe "with width" do
     it "returns a String in the same encoding as the original" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.ljust 5
       result.should == "abc  "
-      result.encoding.should equal(Encoding::IBM437)
+      result.encoding.should.equal?(Encoding::IBM437)
     end
   end
 
   describe "with width, pattern" do
     it "returns a String in the compatible encoding" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.ljust 5, "あ"
       result.should == "abcああ"
-      result.encoding.should equal(Encoding::UTF_8)
+      result.encoding.should.equal?(Encoding::UTF_8)
     end
 
     it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
       pat = "ア".encode Encoding::EUC_JP
       -> do
         "あれ".ljust 5, pat
-      end.should raise_error(Encoding::CompatibilityError)
+      end.should.raise(Encoding::CompatibilityError)
     end
   end
 end
diff --git a/spec/ruby/core/string/lstrip_spec.rb b/spec/ruby/core/string/lstrip_spec.rb
index 7f9363d398..5896f8d7da 100644
--- a/spec/ruby/core/string/lstrip_spec.rb
+++ b/spec/ruby/core/string/lstrip_spec.rb
@@ -1,35 +1,37 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/strip'
 
 describe "String#lstrip" do
+  it_behaves_like :string_strip, :lstrip
+
   it "returns a copy of self with leading whitespace removed" do
-   "  hello  ".lstrip.should == "hello  "
-   "  hello world  ".lstrip.should == "hello world  "
-   "\n\r\t\n\v\r hello world  ".lstrip.should == "hello world  "
-   "hello".lstrip.should == "hello"
-   "\000 \000hello\000 \000".lstrip.should == "\000 \000hello\000 \000"
+    "  hello  ".lstrip.should == "hello  "
+    "  hello world  ".lstrip.should == "hello world  "
+    "\n\r\t\n\v\r hello world  ".lstrip.should == "hello world  "
+    "hello".lstrip.should == "hello"
+    " こにちわ".lstrip.should == "こにちわ"
   end
 
-  it "does not strip leading \\0" do
-   "\x00hello".lstrip.should == "\x00hello"
+  it "works with lazy substrings" do
+    "  hello  "[1...-1].lstrip.should == "hello "
+    "  hello world  "[1...-1].lstrip.should == "hello world "
+    "\n\r\t\n\v\r hello world  "[1...-1].lstrip.should == "hello world "
+    "   こにちわ "[1...-1].lstrip.should == "こにちわ"
   end
 
-  it "taints the result when self is tainted" do
-    "".taint.lstrip.tainted?.should == true
-    "ok".taint.lstrip.tainted?.should == true
-    "   ok".taint.lstrip.tainted?.should == true
+  it "strips leading \\0" do
+    "\x00hello".lstrip.should == "hello"
+    "\000 \000hello\000 \000".lstrip.should == "hello\000 \000"
   end
 end
 
 describe "String#lstrip!" do
   it "modifies self in place and returns self" do
     a = "  hello  "
-    a.lstrip!.should equal(a)
+    a.lstrip!.should.equal?(a)
     a.should == "hello  "
-
-    a = "\000 \000hello\000 \000"
-    a.lstrip!
-    a.should == "\000 \000hello\000 \000"
   end
 
   it "returns nil if no modifications were made" do
@@ -38,13 +40,35 @@ describe "String#lstrip!" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "  hello  ".freeze.lstrip! }.should raise_error(frozen_error_class)
+  it "makes a string empty if it is only whitespace" do
+    "".lstrip!.should == nil
+    " ".lstrip.should == ""
+    "  ".lstrip.should == ""
+  end
+
+  it "removes leading NULL bytes and whitespace" do
+    a = "\000 \000hello\000 \000"
+    a.lstrip!
+    a.should == "hello\000 \000"
+  end
+
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "  hello  ".freeze.lstrip! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23657]
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> { "hello".freeze.lstrip! }.should raise_error(frozen_error_class)
-    -> { "".freeze.lstrip!      }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> { "hello".freeze.lstrip! }.should.raise(FrozenError)
+    -> { "".freeze.lstrip!      }.should.raise(FrozenError)
+  end
+
+  it "raises an ArgumentError if the first non-space codepoint is invalid" do
+    s = "\xDFabc".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.lstrip! }.should.raise(ArgumentError)
+
+    s = "   \xDFabc".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.lstrip! }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/match_spec.rb b/spec/ruby/core/string/match_spec.rb
index 78b94baa44..3ea8d90aa8 100644
--- a/spec/ruby/core/string/match_spec.rb
+++ b/spec/ruby/core/string/match_spec.rb
@@ -19,8 +19,8 @@ describe "String#=~" do
   end
 
   it "raises a TypeError if a obj is a string" do
-    -> { "some string" =~ "another string" }.should raise_error(TypeError)
-    -> { "a" =~ StringSpecs::MyString.new("b")          }.should raise_error(TypeError)
+    -> { "some string" =~ "another string" }.should.raise(TypeError)
+    -> { "a" =~ StringSpecs::MyString.new("b")          }.should.raise(TypeError)
   end
 
   it "invokes obj.=~ with self if obj is neither a string nor regexp" do
@@ -81,7 +81,7 @@ describe "String#match" do
   describe "when passed a block" do
     it "yields the MatchData" do
       "abc".match(/./) {|m| ScratchPad.record m }
-      ScratchPad.recorded.should be_kind_of(MatchData)
+      ScratchPad.recorded.should.is_a?(MatchData)
     end
 
     it "returns the block result" do
@@ -107,9 +107,9 @@ describe "String#match" do
   end
 
   it "raises a TypeError if pattern is not a regexp or a string" do
-    -> { 'hello'.match(10)   }.should raise_error(TypeError)
+    -> { 'hello'.match(10)   }.should.raise(TypeError)
     not_supported_on :opal do
-      -> { 'hello'.match(:ell) }.should raise_error(TypeError)
+      -> { 'hello'.match(:ell) }.should.raise(TypeError)
     end
   end
 
@@ -137,9 +137,17 @@ describe "String#match" do
   end
 
   it "calls match on the regular expression" do
-    regexp = /./
-    regexp.should_receive(:match).and_return(:foo)
-    'hello'.match(regexp).should == :foo
+    # Can't use regexp.should_receive(:match).and_return(:foo) since regexps are frozen
+    ScratchPad.clear
+    regexp = Class.new(Regexp) {
+      def match(*args)
+        ScratchPad.record [:match, *args]
+        super(*args)
+      end
+    }.new('.')
+
+    'hello'.match(regexp)
+    ScratchPad.recorded.should == [:match, 'hello']
   end
 end
 
@@ -151,17 +159,17 @@ describe "String#match?" do
 
   context "when matches the given regex" do
     it "returns true but does not set Regexp.last_match" do
-      'string'.match?(/string/i).should be_true
-      Regexp.last_match.should be_nil
+      'string'.match?(/string/i).should == true
+      Regexp.last_match.should == nil
     end
   end
 
   it "returns false when does not match the given regex" do
-    'string'.match?(/STRING/).should be_false
+    'string'.match?(/STRING/).should == false
   end
 
   it "takes matching position as the 2nd argument" do
-    'string'.match?(/str/i, 0).should be_true
-    'string'.match?(/str/i, 1).should be_false
+    'string'.match?(/str/i, 0).should == true
+    'string'.match?(/str/i, 1).should == false
   end
 end
diff --git a/spec/ruby/core/string/modulo_spec.rb b/spec/ruby/core/string/modulo_spec.rb
index 0ac0963403..f93ec4bcf8 100644
--- a/spec/ruby/core/string/modulo_spec.rb
+++ b/spec/ruby/core/string/modulo_spec.rb
@@ -1,8 +1,22 @@
 require_relative '../../spec_helper'
+require_relative '../kernel/shared/sprintf'
+require_relative '../kernel/shared/sprintf_encoding'
 require_relative 'fixtures/classes'
 require_relative '../../shared/hash/key_error'
 
 describe "String#%" do
+  it_behaves_like :kernel_sprintf, -> format, *args {
+    format % args
+  }
+
+  it_behaves_like :kernel_sprintf_encoding, -> format, *args {
+    format % args
+  }
+end
+
+# TODO: these specs are mostly redundant with kernel/shared/sprintf.rb specs.
+# These specs should be moved there and deduplicated.
+describe "String#%" do
   context "when key is missing from passed-in hash" do
     it_behaves_like :key_error, -> obj, key { "%{#{key}}" % obj }, { a: 5 }
   end
@@ -32,51 +46,57 @@ describe "String#%" do
     end
 
     it "raises if a compatible encoding can't be found" do
-      -> { "hello %s".encode("utf-8") % "world".encode("UTF-16LE") }.should raise_error(Encoding::CompatibilityError)
+      -> { "hello %s".encode("utf-8") % "world".encode("UTF-16LE") }.should.raise(Encoding::CompatibilityError)
     end
   end
 
-  ruby_version_is ""..."2.5" do
-    it "formats single % character at the end as literal %" do
-      ("%" % []).should == "%"
-      ("foo%" % []).should == "foo%"
-    end
+  it "raises an error if single % appears at the end" do
+    -> { ("%" % []) }.should.raise(ArgumentError)
+    -> { ("foo%" % [])}.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.5" do
-    it "raises an error if single % appears at the end" do
-      -> { ("%" % []) }.should raise_error(ArgumentError)
-      -> { ("foo%" % [])}.should raise_error(ArgumentError)
+  ruby_version_is ""..."3.4" do
+    it "formats single % character before a newline as literal %" do
+      ("%\n" % []).should == "%\n"
+      ("foo%\n" % []).should == "foo%\n"
+      ("%\n.3f" % 1.2).should == "%\n.3f"
     end
-  end
 
-  it "formats single % character before a newline as literal %" do
-    ("%\n" % []).should == "%\n"
-    ("foo%\n" % []).should == "foo%\n"
-    ("%\n.3f" % 1.2).should == "%\n.3f"
-  end
+    it "formats single % character before a NUL as literal %" do
+      ("%\0" % []).should == "%\0"
+      ("foo%\0" % []).should == "foo%\0"
+      ("%\0.3f" % 1.2).should == "%\0.3f"
+    end
 
-  it "formats single % character before a NUL as literal %" do
-    ("%\0" % []).should == "%\0"
-    ("foo%\0" % []).should == "foo%\0"
-    ("%\0.3f" % 1.2).should == "%\0.3f"
-  end
+    it "raises an error if single % appears anywhere else" do
+      -> { (" % " % []) }.should.raise(ArgumentError)
+      -> { ("foo%quux" % []) }.should.raise(ArgumentError)
+    end
 
-  it "raises an error if single % appears anywhere else" do
-    -> { (" % " % []) }.should raise_error(ArgumentError)
-    -> { ("foo%quux" % []) }.should raise_error(ArgumentError)
-  end
+    it "raises an error if NULL or \\n appear anywhere else in the format string" do
+      begin
+        old_debug, $DEBUG = $DEBUG, false
 
-  it "raises an error if NULL or \\n appear anywhere else in the format string" do
-    begin
-      old_debug, $DEBUG = $DEBUG, false
+        -> { "%.\n3f" % 1.2 }.should.raise(ArgumentError)
+        -> { "%.3\nf" % 1.2 }.should.raise(ArgumentError)
+        -> { "%.\03f" % 1.2 }.should.raise(ArgumentError)
+        -> { "%.3\0f" % 1.2 }.should.raise(ArgumentError)
+      ensure
+        $DEBUG = old_debug
+      end
+    end
+  end
 
-      -> { "%.\n3f" % 1.2 }.should raise_error(ArgumentError)
-      -> { "%.3\nf" % 1.2 }.should raise_error(ArgumentError)
-      -> { "%.\03f" % 1.2 }.should raise_error(ArgumentError)
-      -> { "%.3\0f" % 1.2 }.should raise_error(ArgumentError)
-    ensure
-      $DEBUG = old_debug
+  ruby_version_is "3.4" do
+    it "raises an ArgumentError if % is not followed by a conversion specifier" do
+      -> { "%" % [] }.should.raise(ArgumentError)
+      -> { "%\n" % [] }.should.raise(ArgumentError)
+      -> { "%\0" % [] }.should.raise(ArgumentError)
+      -> { " % " % [] }.should.raise(ArgumentError)
+      -> { "%.\n3f" % 1.2 }.should.raise(ArgumentError)
+      -> { "%.3\nf" % 1.2 }.should.raise(ArgumentError)
+      -> { "%.\03f" % 1.2 }.should.raise(ArgumentError)
+      -> { "%.3\0f" % 1.2 }.should.raise(ArgumentError)
     end
   end
 
@@ -99,8 +119,8 @@ describe "String#%" do
       s = $stderr
       $stderr = IOStub.new
 
-      -> { "" % [1, 2, 3]   }.should raise_error(ArgumentError)
-      -> { "%s" % [1, 2, 3] }.should raise_error(ArgumentError)
+      -> { "" % [1, 2, 3]   }.should.raise(ArgumentError)
+      -> { "%s" % [1, 2, 3] }.should.raise(ArgumentError)
     ensure
       $DEBUG = old_debug
       $stderr = s
@@ -120,26 +140,34 @@ describe "String#%" do
     end
   end
 
-  it "replaces trailing absolute argument specifier without type with percent sign" do
-    ("hello %1$" % "foo").should == "hello %"
+  ruby_version_is ""..."3.4" do
+    it "replaces trailing absolute argument specifier without type with percent sign" do
+      ("hello %1$" % "foo").should == "hello %"
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "raises an ArgumentError if absolute argument specifier is followed by a conversion specifier" do
+      -> { "hello %1$" % "foo" }.should.raise(ArgumentError)
+    end
   end
 
   it "raises an ArgumentError when given invalid argument specifiers" do
-    -> { "%1" % [] }.should raise_error(ArgumentError)
-    -> { "%+" % [] }.should raise_error(ArgumentError)
-    -> { "%-" % [] }.should raise_error(ArgumentError)
-    -> { "%#" % [] }.should raise_error(ArgumentError)
-    -> { "%0" % [] }.should raise_error(ArgumentError)
-    -> { "%*" % [] }.should raise_error(ArgumentError)
-    -> { "%." % [] }.should raise_error(ArgumentError)
-    -> { "%_" % [] }.should raise_error(ArgumentError)
-    -> { "%0$s" % "x"              }.should raise_error(ArgumentError)
-    -> { "%*0$s" % [5, "x"]        }.should raise_error(ArgumentError)
-    -> { "%*1$.*0$1$s" % [1, 2, 3] }.should raise_error(ArgumentError)
+    -> { "%1" % [] }.should.raise(ArgumentError)
+    -> { "%+" % [] }.should.raise(ArgumentError)
+    -> { "%-" % [] }.should.raise(ArgumentError)
+    -> { "%#" % [] }.should.raise(ArgumentError)
+    -> { "%0" % [] }.should.raise(ArgumentError)
+    -> { "%*" % [] }.should.raise(ArgumentError)
+    -> { "%." % [] }.should.raise(ArgumentError)
+    -> { "%_" % [] }.should.raise(ArgumentError)
+    -> { "%0$s" % "x"              }.should.raise(ArgumentError)
+    -> { "%*0$s" % [5, "x"]        }.should.raise(ArgumentError)
+    -> { "%*1$.*0$1$s" % [1, 2, 3] }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when multiple positional argument tokens are given for one format specifier" do
-    -> { "%1$1$s" % "foo" }.should raise_error(ArgumentError)
+    -> { "%1$1$s" % "foo" }.should.raise(ArgumentError)
   end
 
   it "respects positional arguments and precision tokens given for one format specifier" do
@@ -155,36 +183,36 @@ describe "String#%" do
   end
 
   it "raises an ArgumentError when multiple width star tokens are given for one format specifier" do
-    -> { "%**s" % [5, 5, 5] }.should raise_error(ArgumentError)
+    -> { "%**s" % [5, 5, 5] }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when a width star token is seen after a width token" do
-    -> { "%5*s" % [5, 5] }.should raise_error(ArgumentError)
+    -> { "%5*s" % [5, 5] }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when multiple precision tokens are given" do
-    -> { "%.5.5s" % 5      }.should raise_error(ArgumentError)
-    -> { "%.5.*s" % [5, 5] }.should raise_error(ArgumentError)
-    -> { "%.*.5s" % [5, 5] }.should raise_error(ArgumentError)
+    -> { "%.5.5s" % 5      }.should.raise(ArgumentError)
+    -> { "%.5.*s" % [5, 5] }.should.raise(ArgumentError)
+    -> { "%.*.5s" % [5, 5] }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when there are less arguments than format specifiers" do
     ("foo" % []).should == "foo"
-    -> { "%s" % []     }.should raise_error(ArgumentError)
-    -> { "%s %s" % [1] }.should raise_error(ArgumentError)
+    -> { "%s" % []     }.should.raise(ArgumentError)
+    -> { "%s %s" % [1] }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when absolute and relative argument numbers are mixed" do
-    -> { "%s %1$s" % "foo" }.should raise_error(ArgumentError)
-    -> { "%1$s %s" % "foo" }.should raise_error(ArgumentError)
+    -> { "%s %1$s" % "foo" }.should.raise(ArgumentError)
+    -> { "%1$s %s" % "foo" }.should.raise(ArgumentError)
 
-    -> { "%s %2$s" % ["foo", "bar"] }.should raise_error(ArgumentError)
-    -> { "%2$s %s" % ["foo", "bar"] }.should raise_error(ArgumentError)
+    -> { "%s %2$s" % ["foo", "bar"] }.should.raise(ArgumentError)
+    -> { "%2$s %s" % ["foo", "bar"] }.should.raise(ArgumentError)
 
-    -> { "%*2$s" % [5, 5, 5]     }.should raise_error(ArgumentError)
-    -> { "%*.*2$s" % [5, 5, 5]   }.should raise_error(ArgumentError)
-    -> { "%*2$.*2$s" % [5, 5, 5] }.should raise_error(ArgumentError)
-    -> { "%*.*2$s" % [5, 5, 5]   }.should raise_error(ArgumentError)
+    -> { "%*2$s" % [5, 5, 5]     }.should.raise(ArgumentError)
+    -> { "%*.*2$s" % [5, 5, 5]   }.should.raise(ArgumentError)
+    -> { "%*2$.*2$s" % [5, 5, 5] }.should.raise(ArgumentError)
+    -> { "%*.*2$s" % [5, 5, 5]   }.should.raise(ArgumentError)
   end
 
   it "allows reuse of the one argument multiple via absolute argument numbers" do
@@ -193,13 +221,13 @@ describe "String#%" do
   end
 
   it "always interprets an array argument as a list of argument parameters" do
-    -> { "%p" % [] }.should raise_error(ArgumentError)
+    -> { "%p" % [] }.should.raise(ArgumentError)
     ("%p" % [1]).should == "1"
     ("%p %p" % [1, 2]).should == "1 2"
   end
 
   it "always interprets an array subclass argument as a list of argument parameters" do
-    -> { "%p" % StringSpecs::MyArray[] }.should raise_error(ArgumentError)
+    -> { "%p" % StringSpecs::MyArray[] }.should.raise(ArgumentError)
     ("%p" % StringSpecs::MyArray[1]).should == "1"
     ("%p %p" % StringSpecs::MyArray[1, 2]).should == "1 2"
   end
@@ -270,7 +298,7 @@ describe "String#%" do
     x = mock("string modulo to_ary")
     x.should_receive(:to_ary).and_return("x")
 
-    -> { "%s" % x }.should raise_error(TypeError)
+    -> { "%s" % x }.should.raise(TypeError)
   end
 
   it "tries to convert the argument to Array by calling #to_ary" do
@@ -293,28 +321,7 @@ describe "String#%" do
       "%f", "%g", "%G", "%i", "%o", "%p",
       "%s", "%u", "%x", "%X"
     ].each do |format|
-      (StringSpecs::MyString.new(format) % universal).should be_an_instance_of(String)
-    end
-  end
-
-  it "always taints the result when the format string is tainted" do
-    universal = mock('0')
-    def universal.to_int() 0 end
-    def universal.to_str() "0" end
-    def universal.to_f() 0.0 end
-
-    [
-      "", "foo",
-      "%b", "%B", "%c", "%d", "%e", "%E",
-      "%f", "%g", "%G", "%i", "%o", "%p",
-      "%s", "%u", "%x", "%X"
-    ].each do |format|
-      subcls_format = StringSpecs::MyString.new(format)
-      subcls_format.taint
-      format.taint
-
-      (format % universal).tainted?.should == true
-      (subcls_format % universal).tainted?.should == true
+      (StringSpecs::MyString.new(format) % universal).should.instance_of?(String)
     end
   end
 
@@ -377,15 +384,15 @@ describe "String#%" do
     ("%*c" % [10, 3]).should == "         \003"
     ("%c" % 42).should == "*"
 
-    -> { "%c" % Object }.should raise_error(TypeError)
+    -> { "%c" % Object }.should.raise(TypeError)
   end
 
   it "supports single character strings as argument for %c" do
     ("%c" % 'A').should == "A"
   end
 
-  it "raises an exception for multiple character strings as argument for %c" do
-    -> { "%c" % 'AA' }.should raise_error(ArgumentError)
+  it "supports only the first character as argument for %c" do
+    ("%c" % 'AA').should == "A"
   end
 
   it "calls to_str on argument for %c formats" do
@@ -555,7 +562,7 @@ describe "String#%" do
     ("%1$p" % [10, 5]).should == "10"
     ("%-22p" % 10).should == "10                    "
     ("%*p" % [10, 10]).should == "        10"
-    ("%p" % {capture: 1}).should == "{:capture=>1}"
+    ("%p" % {capture: 1}).should == {capture: 1}.inspect
     ("%p" % "str").should == "\"str\""
   end
 
@@ -571,18 +578,6 @@ describe "String#%" do
     # ("%p" % obj).should == "obj"
   end
 
-  it "taints result for %p when argument.inspect is tainted" do
-    obj = mock('x')
-    def obj.inspect() "x".taint end
-
-    ("%p" % obj).tainted?.should == true
-
-    obj = mock('x'); obj.taint
-    def obj.inspect() "x" end
-
-    ("%p" % obj).tainted?.should == false
-  end
-
   it "supports string formats using %s" do
     ("%s" % "hello").should == "hello"
     ("%s" % "").should == ""
@@ -611,16 +606,11 @@ describe "String#%" do
     # ("%s" % obj).should == "obj"
   end
 
-  it "taints result for %s when argument is tainted" do
-    ("%s" % "x".taint).tainted?.should == true
-    ("%s" % mock('x').taint).tainted?.should == true
-  end
-
   # MRI crashes on this one.
   # See http://groups.google.com/group/ruby-core-google/t/c285c18cd94c216d
   it "raises an ArgumentError for huge precisions for %s" do
     block = -> { "%.25555555555555555555555555555555555555s" % "hello world" }
-    block.should raise_error(ArgumentError)
+    block.should.raise(ArgumentError)
   end
 
   # Note: %u has been changed to an alias for %d in 1.9.
@@ -715,16 +705,16 @@ describe "String#%" do
       -> {
         # see [ruby-core:14139] for more details
         (format % "0777").should == (format % Kernel.Integer("0777"))
-      }.should_not raise_error(ArgumentError)
+      }.should_not.raise(ArgumentError)
 
-      -> { format % "0__7_7_7" }.should raise_error(ArgumentError)
+      -> { format % "0__7_7_7" }.should.raise(ArgumentError)
 
-      -> { format % "" }.should raise_error(ArgumentError)
-      -> { format % "x" }.should raise_error(ArgumentError)
-      -> { format % "5x" }.should raise_error(ArgumentError)
-      -> { format % "08" }.should raise_error(ArgumentError)
-      -> { format % "0b2" }.should raise_error(ArgumentError)
-      -> { format % "123__456" }.should raise_error(ArgumentError)
+      -> { format % "" }.should.raise(ArgumentError)
+      -> { format % "x" }.should.raise(ArgumentError)
+      -> { format % "5x" }.should.raise(ArgumentError)
+      -> { format % "08" }.should.raise(ArgumentError)
+      -> { format % "0b2" }.should.raise(ArgumentError)
+      -> { format % "123__456" }.should.raise(ArgumentError)
 
       obj = mock('5')
       obj.should_receive(:to_i).and_return(5)
@@ -751,21 +741,25 @@ describe "String#%" do
       (format % "-10.4e-20").should == (format % -10.4e-20)
       (format % ".5").should == (format % 0.5)
       (format % "-.5").should == (format % -0.5)
+
+      ruby_version_is "3.4" do
+        (format % "10.").should == (format % 10)
+      end
+
       # Something's strange with this spec:
       # it works just fine in individual mode, but not when run as part of a group
       (format % "10_1_0.5_5_5").should == (format % 1010.555)
 
       (format % "0777").should == (format % 777)
 
-      -> { format % "" }.should raise_error(ArgumentError)
-      -> { format % "x" }.should raise_error(ArgumentError)
-      -> { format % "." }.should raise_error(ArgumentError)
-      -> { format % "10." }.should raise_error(ArgumentError)
-      -> { format % "5x" }.should raise_error(ArgumentError)
-      -> { format % "0b1" }.should raise_error(ArgumentError)
-      -> { format % "10e10.5" }.should raise_error(ArgumentError)
-      -> { format % "10__10" }.should raise_error(ArgumentError)
-      -> { format % "10.10__10" }.should raise_error(ArgumentError)
+      -> { format % "" }.should.raise(ArgumentError)
+      -> { format % "x" }.should.raise(ArgumentError)
+      -> { format % "." }.should.raise(ArgumentError)
+      -> { format % "5x" }.should.raise(ArgumentError)
+      -> { format % "0b1" }.should.raise(ArgumentError)
+      -> { format % "10e10.5" }.should.raise(ArgumentError)
+      -> { format % "10__10" }.should.raise(ArgumentError)
+      -> { format % "10.10__10" }.should.raise(ArgumentError)
 
       obj = mock('5.0')
       obj.should_receive(:to_f).and_return(5.0)
@@ -775,10 +769,6 @@ describe "String#%" do
     it "behaves as if calling Kernel#Float for #{format} arguments, when the passed argument is hexadecimal string" do
       (format % "0xA").should == (format % 0xA)
     end
-
-    it "doesn't taint the result for #{format} when argument is tainted" do
-      (format % "5".taint).tainted?.should == false
-    end
   end
 
   describe "when format string contains %{} sections" do
@@ -787,7 +777,7 @@ describe "String#%" do
     end
 
     it "should raise ArgumentError if no hash given" do
-      -> {"%{foo}" % []}.should raise_error(ArgumentError)
+      -> {"%{foo}" % []}.should.raise(ArgumentError)
     end
   end
 
@@ -797,11 +787,11 @@ describe "String#%" do
     end
 
     it "raises KeyError if key is missing from passed-in hash" do
-      -> {"%<foo>d" % {}}.should raise_error(KeyError)
+      -> {"%<foo>d" % {}}.should.raise(KeyError)
     end
 
     it "should raise ArgumentError if no hash given" do
-      -> {"%<foo>" % []}.should raise_error(ArgumentError)
+      -> {"%<foo>" % []}.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/core/string/new_spec.rb b/spec/ruby/core/string/new_spec.rb
index ca678f5323..aadf1e0e46 100644
--- a/spec/ruby/core/string/new_spec.rb
+++ b/spec/ruby/core/string/new_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "String.new" do
   it "returns an instance of String" do
     str = String.new
-    str.should be_an_instance_of(String)
+    str.should.instance_of?(String)
   end
 
   it "accepts an encoding argument" do
@@ -28,7 +28,7 @@ describe "String.new" do
   it "returns a new string given a string argument" do
     str1 = "test"
     str = String.new(str1)
-    str.should be_an_instance_of(String)
+    str.should.instance_of?(String)
     str.should == str1
     str << "more"
     str.should == "testmore"
@@ -36,7 +36,7 @@ describe "String.new" do
 
   it "returns an instance of a subclass" do
     a = StringSpecs::MyString.new("blah")
-    a.should be_an_instance_of(StringSpecs::MyString)
+    a.should.instance_of?(StringSpecs::MyString)
     a.should == "blah"
   end
 
@@ -51,8 +51,8 @@ describe "String.new" do
   end
 
   it "raises TypeError on inconvertible object" do
-    -> { String.new 5 }.should raise_error(TypeError)
-    -> { String.new nil }.should raise_error(TypeError)
+    -> { String.new 5 }.should.raise(TypeError)
+    -> { String.new nil }.should.raise(TypeError)
   end
 
   it "returns a binary String" do
diff --git a/spec/ruby/core/string/ord_spec.rb b/spec/ruby/core/string/ord_spec.rb
index 0f5a3f6a37..5a17fc1d87 100644
--- a/spec/ruby/core/string/ord_spec.rb
+++ b/spec/ruby/core/string/ord_spec.rb
@@ -1,8 +1,8 @@
 require_relative '../../spec_helper'
 
 describe "String#ord" do
-  it "returns a Fixnum" do
-    'a'.ord.should be_an_instance_of(Fixnum)
+  it "returns an Integer" do
+    'a'.ord.should.instance_of?(Integer)
   end
 
   it "returns the codepoint of the first character in the String" do
@@ -23,6 +23,11 @@ describe "String#ord" do
   end
 
   it "raises an ArgumentError if called on an empty String" do
-    -> { ''.ord }.should raise_error(ArgumentError)
+    -> { ''.ord }.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError if the character is broken" do
+    s = "©".dup.force_encoding("US-ASCII")
+    -> { s.ord }.should.raise(ArgumentError, "invalid byte sequence in US-ASCII")
   end
 end
diff --git a/spec/ruby/core/string/partition_spec.rb b/spec/ruby/core/string/partition_spec.rb
index 996368d6a4..29fe910b39 100644
--- a/spec/ruby/core/string/partition_spec.rb
+++ b/spec/ruby/core/string/partition_spec.rb
@@ -1,7 +1,10 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/partition'
 
 describe "String#partition with String" do
+  it_behaves_like :string_partition, :partition
+
   it "returns an array of substrings based on splitting on the given string" do
     "hello world".partition("o").should == ["hell", "o", " world"]
   end
@@ -28,11 +31,33 @@ describe "String#partition with String" do
   end
 
   it "raises an error if not convertible to string" do
-    ->{ "hello".partition(5) }.should raise_error(TypeError)
-    ->{ "hello".partition(nil) }.should raise_error(TypeError)
+    ->{ "hello".partition(5) }.should.raise(TypeError)
+    ->{ "hello".partition(nil) }.should.raise(TypeError)
   end
 
   it "takes precedence over a given block" do
     "hello world".partition("o") { true }.should == ["hell", "o", " world"]
   end
+
+  it "handles a pattern in a superset encoding" do
+    string = "hello".dup.force_encoding(Encoding::US_ASCII)
+
+    result = string.partition("é")
+
+    result.should == ["hello", "", ""]
+    result[0].encoding.should == Encoding::US_ASCII
+    result[1].encoding.should == Encoding::US_ASCII
+    result[2].encoding.should == Encoding::US_ASCII
+  end
+
+  it "handles a pattern in a subset encoding" do
+    pattern = "o".dup.force_encoding(Encoding::US_ASCII)
+
+    result = "héllo world".partition(pattern)
+
+    result.should == ["héll", "o", " world"]
+    result[0].encoding.should == Encoding::UTF_8
+    result[1].encoding.should == Encoding::US_ASCII
+    result[2].encoding.should == Encoding::UTF_8
+  end
 end
diff --git a/spec/ruby/core/string/percent_spec.rb b/spec/ruby/core/string/percent_spec.rb
deleted file mode 100644
index e3460522b1..0000000000
--- a/spec/ruby/core/string/percent_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../spec_helper'
-require_relative '../kernel/shared/sprintf'
-require_relative '../kernel/shared/sprintf_encoding'
-
-describe "String#%" do
-  it_behaves_like :kernel_sprintf, -> format, *args {
-    format % args
-  }
-
-  it_behaves_like :kernel_sprintf_encoding, -> format, *args {
-    format % args
-  }
-end
diff --git a/spec/ruby/core/string/plus_spec.rb b/spec/ruby/core/string/plus_spec.rb
index b8e3bf0a4b..0464141c37 100644
--- a/spec/ruby/core/string/plus_spec.rb
+++ b/spec/ruby/core/string/plus_spec.rb
@@ -3,6 +3,9 @@ require_relative 'fixtures/classes'
 require_relative 'shared/concat'
 
 describe "String#+" do
+  it_behaves_like :string_concat_encoding, :+
+  it_behaves_like :string_concat_type_coercion, :+
+
   it "returns a new string containing the given string concatenated to self" do
     ("" + "").should == ""
     ("" + "Hello").should == "Hello"
@@ -18,30 +21,17 @@ describe "String#+" do
   end
 
   it "raises a TypeError when given any object that fails #to_str" do
-    -> { "" + Object.new }.should raise_error(TypeError)
-    -> { "" + 65 }.should raise_error(TypeError)
+    -> { "" + Object.new }.should.raise(TypeError)
+    -> { "" + 65 }.should.raise(TypeError)
   end
 
   it "doesn't return subclass instances" do
-    (StringSpecs::MyString.new("hello") + "").should be_an_instance_of(String)
-    (StringSpecs::MyString.new("hello") + "foo").should be_an_instance_of(String)
-    (StringSpecs::MyString.new("hello") + StringSpecs::MyString.new("foo")).should be_an_instance_of(String)
-    (StringSpecs::MyString.new("hello") + StringSpecs::MyString.new("")).should be_an_instance_of(String)
-    (StringSpecs::MyString.new("") + StringSpecs::MyString.new("")).should be_an_instance_of(String)
-    ("hello" + StringSpecs::MyString.new("foo")).should be_an_instance_of(String)
-    ("hello" + StringSpecs::MyString.new("")).should be_an_instance_of(String)
+    (StringSpecs::MyString.new("hello") + "").should.instance_of?(String)
+    (StringSpecs::MyString.new("hello") + "foo").should.instance_of?(String)
+    (StringSpecs::MyString.new("hello") + StringSpecs::MyString.new("foo")).should.instance_of?(String)
+    (StringSpecs::MyString.new("hello") + StringSpecs::MyString.new("")).should.instance_of?(String)
+    (StringSpecs::MyString.new("") + StringSpecs::MyString.new("")).should.instance_of?(String)
+    ("hello" + StringSpecs::MyString.new("foo")).should.instance_of?(String)
+    ("hello" + StringSpecs::MyString.new("")).should.instance_of?(String)
   end
-
-  it "taints the result when self or other is tainted" do
-    strs = ["", "OK", StringSpecs::MyString.new(""), StringSpecs::MyString.new("OK")]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      strs.each do |other|
-        (str + other).tainted?.should == (str.tainted? | other.tainted?)
-      end
-    end
-  end
-
-  it_behaves_like :string_concat_encoding, :+
 end
diff --git a/spec/ruby/core/string/prepend_spec.rb b/spec/ruby/core/string/prepend_spec.rb
index 485c578e2d..a8da4e62cb 100644
--- a/spec/ruby/core/string/prepend_spec.rb
+++ b/spec/ruby/core/string/prepend_spec.rb
@@ -1,10 +1,11 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "String#prepend" do
   it "prepends the given argument to self and returns self" do
     str = "world"
-    str.prepend("hello ").should equal(str)
+    str.prepend("hello ").should.equal?(str)
     str.should == "hello world"
   end
 
@@ -16,16 +17,16 @@ describe "String#prepend" do
   end
 
   it "raises a TypeError if the given argument can't be converted to a String" do
-    -> { "hello ".prepend [] }.should raise_error(TypeError)
-    -> { 'hello '.prepend mock('x') }.should raise_error(TypeError)
+    -> { "hello ".prepend [] }.should.raise(TypeError)
+    -> { 'hello '.prepend mock('x') }.should.raise(TypeError)
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     a = "hello"
     a.freeze
 
-    -> { a.prepend "" }.should raise_error(frozen_error_class)
-    -> { a.prepend "test" }.should raise_error(frozen_error_class)
+    -> { a.prepend "" }.should.raise(FrozenError)
+    -> { a.prepend "test" }.should.raise(FrozenError)
   end
 
   it "works when given a subclass instance" do
@@ -34,14 +35,6 @@ describe "String#prepend" do
     a.should == "hello world"
   end
 
-  it "taints self if other is tainted" do
-    x = "x"
-    x.prepend("".taint).tainted?.should be_true
-
-    x = "x"
-    x.prepend("y".taint).tainted?.should be_true
-  end
-
   it "takes multiple arguments" do
     str = " world"
     str.prepend "he", "", "llo"
@@ -56,7 +49,7 @@ describe "String#prepend" do
 
   it "returns self when given no arguments" do
     str = "hello"
-    str.prepend.should equal(str)
+    str.prepend.should.equal?(str)
     str.should == "hello"
   end
 end
diff --git a/spec/ruby/core/string/reverse_spec.rb b/spec/ruby/core/string/reverse_spec.rb
index 3941ea0521..e37c1125db 100644
--- a/spec/ruby/core/string/reverse_spec.rb
+++ b/spec/ruby/core/string/reverse_spec.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
@@ -10,34 +11,46 @@ describe "String#reverse" do
     "".reverse.should == ""
   end
 
-  it "taints the result if self is tainted" do
-    "".taint.reverse.tainted?.should == true
-    "m".taint.reverse.tainted?.should == true
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("stressed").reverse.should.instance_of?(String)
+    StringSpecs::MyString.new("m").reverse.should.instance_of?(String)
+    StringSpecs::MyString.new("").reverse.should.instance_of?(String)
   end
 
   it "reverses a string with multi byte characters" do
     "微軟正黑體".reverse.should == "體黑正軟微"
   end
 
+  it "works with a broken string" do
+    str = "微軟\xDF\xDE正黑體".force_encoding(Encoding::UTF_8)
+
+    str.valid_encoding?.should == false
+
+    str.reverse.should == "體黑正\xDE\xDF軟微"
+  end
+
+  it "returns a String in the same encoding as self" do
+    "stressed".encode("US-ASCII").reverse.encoding.should == Encoding::US_ASCII
+  end
 end
 
 describe "String#reverse!" do
   it "reverses self in place and always returns self" do
     a = "stressed"
-    a.reverse!.should equal(a)
+    a.reverse!.should.equal?(a)
     a.should == "desserts"
 
     "".reverse!.should == ""
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "anna".freeze.reverse!  }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.reverse! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "anna".freeze.reverse!  }.should.raise(FrozenError)
+    -> { "hello".freeze.reverse! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> { "".freeze.reverse! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> { "".freeze.reverse! }.should.raise(FrozenError)
   end
 
   it "reverses a string with multi byte characters" do
@@ -45,4 +58,13 @@ describe "String#reverse!" do
     str.reverse!
     str.should == "體黑正軟微"
   end
+
+  it "works with a broken string" do
+    str = "微軟\xDF\xDE正黑體".force_encoding(Encoding::UTF_8)
+
+    str.valid_encoding?.should == false
+    str.reverse!
+
+    str.should == "體黑正\xDE\xDF軟微"
+  end
 end
diff --git a/spec/ruby/core/string/rindex_spec.rb b/spec/ruby/core/string/rindex_spec.rb
index e021486bc2..acecec224f 100644
--- a/spec/ruby/core/string/rindex_spec.rb
+++ b/spec/ruby/core/string/rindex_spec.rb
@@ -1,20 +1,23 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
-require_relative 'fixtures/utf-8-encoding'
 
 describe "String#rindex with object" do
-  it "raises a TypeError if obj isn't a String, Fixnum or Regexp" do
+  it "raises a TypeError if obj isn't a String or Regexp" do
     not_supported_on :opal do
-      -> { "hello".rindex(:sym) }.should raise_error(TypeError)
+      -> { "hello".rindex(:sym) }.should.raise(TypeError)
     end
-    -> { "hello".rindex(mock('x')) }.should raise_error(TypeError)
+    -> { "hello".rindex(mock('x')) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if obj is an Integer" do
+    -> { "hello".rindex(42) }.should.raise(TypeError)
   end
 
   it "doesn't try to convert obj to an integer via to_int" do
     obj = mock('x')
     obj.should_not_receive(:to_int)
-    -> { "hello".rindex(obj) }.should raise_error(TypeError)
+    -> { "hello".rindex(obj) }.should.raise(TypeError)
   end
 
   it "tries to convert obj to a string via to_str" do
@@ -190,7 +193,22 @@ describe "String#rindex with String" do
   end
 
   it "raises a TypeError when given offset is nil" do
-    -> { "str".rindex("st", nil) }.should raise_error(TypeError)
+    -> { "str".rindex("st", nil) }.should.raise(TypeError)
+  end
+
+  it "handles a substring in a superset encoding" do
+    'abc'.dup.force_encoding(Encoding::US_ASCII).rindex('é').should == nil
+  end
+
+  it "handles a substring in a subset encoding" do
+    'été'.rindex('t'.dup.force_encoding(Encoding::US_ASCII)).should == 1
+  end
+
+  it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
+    str = 'abc'.dup.force_encoding("ISO-2022-JP")
+    pattern = 'b'.dup.force_encoding("EUC-JP")
+
+    -> { str.rindex(pattern) }.should.raise(Encoding::CompatibilityError, "incompatible character encodings: ISO-2022-JP and EUC-JP")
   end
 end
 
@@ -344,7 +362,7 @@ describe "String#rindex with Regexp" do
   end
 
   it "raises a TypeError when given offset is nil" do
-    -> { "str".rindex(/../, nil) }.should raise_error(TypeError)
+    -> { "str".rindex(/../, nil) }.should.raise(TypeError)
   end
 
   it "returns the reverse character index of a multibyte character" do
@@ -353,14 +371,14 @@ describe "String#rindex with Regexp" do
   end
 
   it "returns the character index before the finish" do
-     "ありがりがとう".rindex("が", 3).should == 2
-     "ありがりがとう".rindex(/が/, 3).should == 2
+    "ありがりがとう".rindex("が", 3).should == 2
+    "ありがりがとう".rindex(/が/, 3).should == 2
   end
 
   it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
     re = Regexp.new "れ".encode(Encoding::EUC_JP)
     -> do
       "あれ".rindex re
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError, "incompatible encoding regexp match (EUC-JP regexp with UTF-8 string)")
   end
 end
diff --git a/spec/ruby/core/string/rjust_spec.rb b/spec/ruby/core/string/rjust_spec.rb
index 1ba298e8f3..9f9c369745 100644
--- a/spec/ruby/core/string/rjust_spec.rb
+++ b/spec/ruby/core/string/rjust_spec.rb
@@ -31,14 +31,6 @@ describe "String#rjust with length, padding" do
     "radiology".rjust(8, '-').should == "radiology"
   end
 
-  it "taints result when self or padstr is tainted" do
-    "x".taint.rjust(4).tainted?.should == true
-    "x".taint.rjust(0).tainted?.should == true
-    "".taint.rjust(0).tainted?.should == true
-    "x".taint.rjust(4, "*").tainted?.should == true
-    "x".rjust(4, "*".taint).tainted?.should == true
-  end
-
   it "tries to convert length to an integer using to_int" do
     "^".rjust(3.8, "^_").should == "^_^"
 
@@ -49,10 +41,10 @@ describe "String#rjust with length, padding" do
   end
 
   it "raises a TypeError when length can't be converted to an integer" do
-    -> { "hello".rjust("x")       }.should raise_error(TypeError)
-    -> { "hello".rjust("x", "y")  }.should raise_error(TypeError)
-    -> { "hello".rjust([])        }.should raise_error(TypeError)
-    -> { "hello".rjust(mock('x')) }.should raise_error(TypeError)
+    -> { "hello".rjust("x")       }.should.raise(TypeError)
+    -> { "hello".rjust("x", "y")  }.should.raise(TypeError)
+    -> { "hello".rjust([])        }.should.raise(TypeError)
+    -> { "hello".rjust(mock('x')) }.should.raise(TypeError)
   end
 
   it "tries to convert padstr to a string using to_str" do
@@ -63,52 +55,46 @@ describe "String#rjust with length, padding" do
   end
 
   it "raises a TypeError when padstr can't be converted" do
-    -> { "hello".rjust(20, [])        }.should raise_error(TypeError)
-    -> { "hello".rjust(20, Object.new)}.should raise_error(TypeError)
-    -> { "hello".rjust(20, mock('x')) }.should raise_error(TypeError)
+    -> { "hello".rjust(20, [])        }.should.raise(TypeError)
+    -> { "hello".rjust(20, Object.new)}.should.raise(TypeError)
+    -> { "hello".rjust(20, mock('x')) }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError when padstr is empty" do
-    -> { "hello".rjust(10, '') }.should raise_error(ArgumentError)
+    -> { "hello".rjust(10, '') }.should.raise(ArgumentError)
   end
 
-  it "returns subclass instances when called on subclasses" do
-    StringSpecs::MyString.new("").rjust(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").rjust(10).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").rjust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(StringSpecs::MyString)
-
-    "".rjust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-    "foo".rjust(10, StringSpecs::MyString.new("x")).should be_an_instance_of(String)
-  end
+  it "returns String instances when called on subclasses" do
+    StringSpecs::MyString.new("").rjust(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").rjust(10).should.instance_of?(String)
+    StringSpecs::MyString.new("foo").rjust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
 
-  it "when padding is tainted and self is untainted returns a tainted string if and only if length is longer than self" do
-    "hello".rjust(4, 'X'.taint).tainted?.should be_false
-    "hello".rjust(5, 'X'.taint).tainted?.should be_false
-    "hello".rjust(6, 'X'.taint).tainted?.should be_true
+    "".rjust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
+    "foo".rjust(10, StringSpecs::MyString.new("x")).should.instance_of?(String)
   end
 
   describe "with width" do
     it "returns a String in the same encoding as the original" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.rjust 5
       result.should == "  abc"
-      result.encoding.should equal(Encoding::IBM437)
+      result.encoding.should.equal?(Encoding::IBM437)
     end
   end
 
   describe "with width, pattern" do
     it "returns a String in the compatible encoding" do
-      str = "abc".force_encoding Encoding::IBM437
+      str = "abc".dup.force_encoding Encoding::IBM437
       result = str.rjust 5, "あ"
       result.should == "ああabc"
-      result.encoding.should equal(Encoding::UTF_8)
+      result.encoding.should.equal?(Encoding::UTF_8)
     end
 
     it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
       pat = "ア".encode Encoding::EUC_JP
       -> do
         "あれ".rjust 5, pat
-      end.should raise_error(Encoding::CompatibilityError)
+      end.should.raise(Encoding::CompatibilityError)
     end
   end
 end
diff --git a/spec/ruby/core/string/rpartition_spec.rb b/spec/ruby/core/string/rpartition_spec.rb
index c6428636f6..a7dd7430b7 100644
--- a/spec/ruby/core/string/rpartition_spec.rb
+++ b/spec/ruby/core/string/rpartition_spec.rb
@@ -1,7 +1,10 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/partition'
 
 describe "String#rpartition with String" do
+  it_behaves_like :string_partition, :rpartition
+
   it "returns an array of substrings based on splitting on the given string" do
     "hello world".rpartition("o").should == ["hello w", "o", "rld"]
   end
@@ -11,6 +14,19 @@ describe "String#rpartition with String" do
     "hello".rpartition("hello").should == ["", "hello", ""]
   end
 
+  it "returns original string if regexp doesn't match" do
+    "hello".rpartition("/x/").should == ["", "", "hello"]
+  end
+
+  it "returns new object if doesn't match" do
+    str = "hello"
+    str.rpartition("/no_match/").last.should_not.equal?(str)
+  end
+
+  it "handles multibyte string correctly" do
+    "ユーザ@ドメイン".rpartition(/@/).should == ["ユーザ", "@", "ドメイン"]
+  end
+
   it "accepts regexp" do
     "hello!".rpartition(/l./).should == ["hel", "lo", "!"]
   end
@@ -27,7 +43,29 @@ describe "String#rpartition with String" do
   end
 
   it "raises an error if not convertible to string" do
-    ->{ "hello".rpartition(5) }.should raise_error(TypeError)
-    ->{ "hello".rpartition(nil) }.should raise_error(TypeError)
+    ->{ "hello".rpartition(5) }.should.raise(TypeError)
+    ->{ "hello".rpartition(nil) }.should.raise(TypeError)
+  end
+
+  it "handles a pattern in a superset encoding" do
+    string = "hello".dup.force_encoding(Encoding::US_ASCII)
+
+    result = string.rpartition("é")
+
+    result.should == ["", "", "hello"]
+    result[0].encoding.should == Encoding::US_ASCII
+    result[1].encoding.should == Encoding::US_ASCII
+    result[2].encoding.should == Encoding::US_ASCII
+  end
+
+  it "handles a pattern in a subset encoding" do
+    pattern = "o".dup.force_encoding(Encoding::US_ASCII)
+
+    result = "héllo world".rpartition(pattern)
+
+    result.should == ["héllo w", "o", "rld"]
+    result[0].encoding.should == Encoding::UTF_8
+    result[1].encoding.should == Encoding::US_ASCII
+    result[2].encoding.should == Encoding::UTF_8
   end
 end
diff --git a/spec/ruby/core/string/rstrip_spec.rb b/spec/ruby/core/string/rstrip_spec.rb
index 2f32836e54..1638ea375d 100644
--- a/spec/ruby/core/string/rstrip_spec.rb
+++ b/spec/ruby/core/string/rstrip_spec.rb
@@ -1,30 +1,36 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/strip'
 
 describe "String#rstrip" do
+  it_behaves_like :string_strip, :rstrip
+
   it "returns a copy of self with trailing whitespace removed" do
     "  hello  ".rstrip.should == "  hello"
     "  hello world  ".rstrip.should == "  hello world"
     "  hello world \n\r\t\n\v\r".rstrip.should == "  hello world"
     "hello".rstrip.should == "hello"
     "hello\x00".rstrip.should == "hello"
+    "こにちわ ".rstrip.should == "こにちわ"
   end
 
-  it "returns a copy of self with all trailing whitespace and NULL bytes removed" do
-    "\x00 \x00hello\x00 \x00".rstrip.should == "\x00 \x00hello"
+  it "works with lazy substrings" do
+    "  hello  "[1...-1].rstrip.should == " hello"
+    "  hello world  "[1...-1].rstrip.should == " hello world"
+    "  hello world \n\r\t\n\v\r"[1...-1].rstrip.should == " hello world"
+    " こにちわ  "[1...-1].rstrip.should == "こにちわ"
   end
 
-  it "taints the result when self is tainted" do
-    "".taint.rstrip.tainted?.should == true
-    "ok".taint.rstrip.tainted?.should == true
-    "ok    ".taint.rstrip.tainted?.should == true
+  it "returns a copy of self with all trailing whitespace and NULL bytes removed" do
+    "\x00 \x00hello\x00 \x00".rstrip.should == "\x00 \x00hello"
   end
 end
 
 describe "String#rstrip!" do
   it "modifies self in place and returns self" do
     a = "  hello  "
-    a.rstrip!.should equal(a)
+    a.rstrip!.should.equal?(a)
     a.should == "  hello"
   end
 
@@ -40,13 +46,35 @@ describe "String#rstrip!" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "  hello  ".freeze.rstrip! }.should raise_error(frozen_error_class)
+  it "makes a string empty if it is only whitespace" do
+    "".rstrip!.should == nil
+    " ".rstrip.should == ""
+    "  ".rstrip.should == ""
+  end
+
+  it "removes trailing NULL bytes and whitespace" do
+    a = "\000 goodbye \000"
+    a.rstrip!
+    a.should == "\000 goodbye"
+  end
+
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "  hello  ".freeze.rstrip! }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> { "hello".freeze.rstrip! }.should raise_error(frozen_error_class)
-    -> { "".freeze.rstrip!      }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> { "hello".freeze.rstrip! }.should.raise(FrozenError)
+    -> { "".freeze.rstrip!      }.should.raise(FrozenError)
+  end
+
+  it "raises an Encoding::CompatibilityError if the last non-space codepoint is invalid" do
+    s = "abc\xDF".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.rstrip! }.should.raise(Encoding::CompatibilityError)
+
+    s = "abc\xDF   ".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.rstrip! }.should.raise(Encoding::CompatibilityError)
   end
 end
diff --git a/spec/ruby/core/string/scan_spec.rb b/spec/ruby/core/string/scan_spec.rb
index 06400fc745..47fa7214c2 100644
--- a/spec/ruby/core/string/scan_spec.rb
+++ b/spec/ruby/core/string/scan_spec.rb
@@ -58,44 +58,30 @@ describe "String#scan" do
   end
 
   it "raises a TypeError if pattern isn't a Regexp and can't be converted to a String" do
-    -> { "cruel world".scan(5)         }.should raise_error(TypeError)
+    -> { "cruel world".scan(5)         }.should.raise(TypeError)
     not_supported_on :opal do
-      -> { "cruel world".scan(:test)   }.should raise_error(TypeError)
+      -> { "cruel world".scan(:test)   }.should.raise(TypeError)
     end
-    -> { "cruel world".scan(mock('x')) }.should raise_error(TypeError)
-  end
-
-  it "taints the results if the String argument is tainted" do
-    a = "hello hello hello".scan("hello".taint)
-    a.each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results when passed a String argument if self is tainted" do
-    a = "hello hello hello".taint.scan("hello")
-    a.each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results if the Regexp argument is tainted" do
-    a = "hello".scan(/./.taint)
-    a.each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results when passed a Regexp argument if self is tainted" do
-    a = "hello".taint.scan(/./)
-    a.each { |m| m.tainted?.should be_true }
+    -> { "cruel world".scan(mock('x')) }.should.raise(TypeError)
   end
 
   # jruby/jruby#5513
   it "does not raise any errors when passed a multi-byte string" do
     "あああaaaあああ".scan("あああ").should == ["あああ", "あああ"]
   end
+
+  it "returns Strings in the same encoding as self" do
+    "cruel world".encode("US-ASCII").scan(/\w+/).each do |s|
+      s.encoding.should == Encoding::US_ASCII
+    end
+  end
 end
 
 describe "String#scan with pattern and block" do
   it "returns self" do
     s = "foo"
-    s.scan(/./) {}.should equal(s)
-    s.scan(/roar/) {}.should equal(s)
+    s.scan(/./) {}.should.equal?(s)
+    s.scan(/roar/) {}.should.equal?(s)
   end
 
   it "passes each match to the block as one argument: an array" do
@@ -117,11 +103,11 @@ describe "String#scan with pattern and block" do
     offsets = []
 
     str.scan(/([aeiou])/) do
-       md = $~
-       md.string.should == str
-       matches << md.to_a
-       offsets << md.offset(0)
-       str
+      md = $~
+      md.string.should == str
+      matches << md.to_a
+      offsets << md.offset(0)
+      str
     end
 
     matches.should == [["e", "e"], ["o", "o"]]
@@ -131,11 +117,11 @@ describe "String#scan with pattern and block" do
     offsets = []
 
     str.scan("l") do
-       md = $~
-       md.string.should == str
-       matches << md.to_a
-       offsets << md.offset(0)
-       str
+      md = $~
+      md.string.should == str
+      matches << md.to_a
+      offsets << md.offset(0)
+      str
     end
 
     matches.should == [["l"], ["l"]]
@@ -171,22 +157,6 @@ describe "String#scan with pattern and block" do
     $~.should == nil
   end
 
-  it "taints the results if the String argument is tainted" do
-    "hello hello hello".scan("hello".taint).each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results when passed a String argument if self is tainted" do
-    "hello hello hello".taint.scan("hello").each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results if the Regexp argument is tainted" do
-    "hello".scan(/./.taint).each { |m| m.tainted?.should be_true }
-  end
-
-  it "taints the results when passed a Regexp argument if self is tainted" do
-    "hello".taint.scan(/./).each { |m| m.tainted?.should be_true }
-  end
-
   it "passes block arguments as individual arguments when blocks are provided" do
     "a b c\na b c\na b c".scan(/(\w*) (\w*) (\w*)/) do |first,second,third|
       first.should == 'a';
@@ -194,4 +164,10 @@ describe "String#scan with pattern and block" do
       third.should == 'c';
     end
   end
+
+  it "yields String instances for subclasses" do
+    a = []
+    StringSpecs::MyString.new("abc").scan(/./) { |s| a << s.class }
+    a.should == [String, String, String]
+  end
 end
diff --git a/spec/ruby/core/string/scrub_spec.rb b/spec/ruby/core/string/scrub_spec.rb
index 390035ef30..9dc55dbef7 100644
--- a/spec/ruby/core/string/scrub_spec.rb
+++ b/spec/ruby/core/string/scrub_spec.rb
@@ -1,5 +1,7 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "String#scrub with a default replacement" do
   it "returns self for valid strings" do
@@ -13,18 +15,33 @@ describe "String#scrub with a default replacement" do
     "abc\u3042#{x81}".scrub.should == "abc\u3042\uFFFD"
   end
 
+  it "replaces invalid byte sequences in lazy substrings" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}def"[1...-1].scrub.should == "bc\u3042\uFFFDde"
+  end
+
   it "returns a copy of self when the input encoding is BINARY" do
     input = "foo".encode('BINARY')
 
     input.scrub.should == "foo"
   end
 
-
   it "replaces invalid byte sequences when using ASCII as the input encoding" do
     xE3x80 = [0xE3, 0x80].pack('CC').force_encoding 'utf-8'
     input = "abc\u3042#{xE3x80}".force_encoding('ASCII')
     input.scrub.should == "abc?????"
   end
+
+  it "returns a String in the same encoding as self" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}".scrub.encoding.should == Encoding::UTF_8
+  end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub.should.instance_of?(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub.should.instance_of?(String)
+  end
 end
 
 describe "String#scrub with a custom replacement" do
@@ -39,6 +56,15 @@ describe "String#scrub with a custom replacement" do
     "abc\u3042#{x81}".scrub("*").should == "abc\u3042*"
   end
 
+  it "replaces invalid byte sequences in frozen strings" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    (-"abc\u3042#{x81}").scrub("*").should == "abc\u3042*"
+
+    leading_surrogate = [0x00, 0xD8]
+    utf16_str = ("abc".encode('UTF-16LE').bytes + leading_surrogate).pack('c*').force_encoding('UTF-16LE')
+    (-(utf16_str)).scrub("*".encode('UTF-16LE')).should == "abc*".encode('UTF-16LE')
+  end
+
   it "replaces an incomplete character at the end with a single replacement" do
     xE3x80 = [0xE3, 0x80].pack('CC').force_encoding 'utf-8'
     xE3x80.scrub("*").should == "*"
@@ -49,14 +75,25 @@ describe "String#scrub with a custom replacement" do
     xE4 = [0xE4].pack('C').force_encoding('utf-8')
     block = -> { "foo#{x81}".scrub(xE4) }
 
-    block.should raise_error(ArgumentError)
+    block.should.raise(ArgumentError)
+  end
+
+  it "returns a String in the same encoding as self" do
+    x81 = [0x81].pack('C').force_encoding('utf-8')
+    "abc\u3042#{x81}".scrub("*").encoding.should == Encoding::UTF_8
   end
 
   it "raises TypeError when a non String replacement is given" do
     x81 = [0x81].pack('C').force_encoding('utf-8')
     block = -> { "foo#{x81}".scrub(1) }
 
-    block.should raise_error(TypeError)
+    block.should.raise(TypeError)
+  end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub("*").should.instance_of?(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub("*").should.instance_of?(String)
   end
 end
 
@@ -82,6 +119,12 @@ describe "String#scrub with a block" do
 
     replaced.should == "€€"
   end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("foo").scrub { |b| "*" }.should.instance_of?(String)
+    input = [0x81].pack('C').force_encoding('utf-8')
+    StringSpecs::MyString.new(input).scrub { |b| "<#{b.unpack("H*")[0]}>" }.should.instance_of?(String)
+  end
 end
 
 describe "String#scrub!" do
@@ -98,4 +141,24 @@ describe "String#scrub!" do
     input.scrub! { |b| "<?>" }
     input.should == "a<?>"
   end
+
+  it "maintains the state of frozen strings that are already valid" do
+    input = "a"
+    input.freeze
+    input.scrub!
+    input.frozen?.should == true
+  end
+
+  it "preserves the instance variables of already valid strings" do
+    input = "a"
+    input.instance_variable_set(:@a, 'b')
+    input.scrub!
+    input.instance_variable_get(:@a).should == 'b'
+  end
+
+  it "accepts a frozen string as a replacement" do
+    input = "a\xE2"
+    input.scrub!('.'.freeze)
+    input.should == 'a.'
+  end
 end
diff --git a/spec/ruby/core/string/setbyte_spec.rb b/spec/ruby/core/string/setbyte_spec.rb
index 6912b1b66f..d9fcc279c0 100644
--- a/spec/ruby/core/string/setbyte_spec.rb
+++ b/spec/ruby/core/string/setbyte_spec.rb
@@ -1,9 +1,10 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#setbyte" do
   it "returns an Integer" do
-    "a".setbyte(0,1).should be_kind_of(Integer)
+    "a".setbyte(0,1).should.is_a?(Integer)
   end
 
   it "modifies the receiver" do
@@ -33,9 +34,15 @@ describe "String#setbyte" do
 
   it "can invalidate a String's encoding" do
     str = "glark"
-    str.valid_encoding?.should be_true
+    str.valid_encoding?.should == true
     str.setbyte(2,253)
-    str.valid_encoding?.should be_false
+    str.valid_encoding?.should == false
+
+    str = "ABC"
+    str.setbyte(0, 0x20) # ' '
+    str.should.valid_encoding?
+    str.setbyte(0, 0xE3)
+    str.should_not.valid_encoding?
   end
 
   it "regards a negative index as counting from the end of the String" do
@@ -51,11 +58,11 @@ describe "String#setbyte" do
   end
 
   it "raises an IndexError if the index is greater than the String bytesize" do
-    -> { "?".setbyte(1, 97) }.should raise_error(IndexError)
+    -> { "?".setbyte(1, 97) }.should.raise(IndexError)
   end
 
   it "raises an IndexError if the negative index is greater magnitude than the String bytesize" do
-    -> { "???".setbyte(-5, 97) }.should raise_error(IndexError)
+    -> { "???".setbyte(-5, 97) }.should.raise(IndexError)
   end
 
   it "sets a byte at an index greater than String size" do
@@ -75,14 +82,14 @@ describe "String#setbyte" do
     str1.should_not == "ledgehog"
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     str = "cold".freeze
-    str.frozen?.should be_true
-    -> { str.setbyte(3,96) }.should raise_error(frozen_error_class)
+    str.frozen?.should == true
+    -> { str.setbyte(3,96) }.should.raise(FrozenError)
   end
 
   it "raises a TypeError unless the second argument is an Integer" do
-    -> { "a".setbyte(0,'a') }.should raise_error(TypeError)
+    -> { "a".setbyte(0,'a') }.should.raise(TypeError)
   end
 
   it "calls #to_int to convert the index" do
diff --git a/spec/ruby/core/string/shared/byte_index_common.rb b/spec/ruby/core/string/shared/byte_index_common.rb
new file mode 100644
index 0000000000..bae6cff49f
--- /dev/null
+++ b/spec/ruby/core/string/shared/byte_index_common.rb
@@ -0,0 +1,63 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../../spec_helper'
+
+describe :byte_index_common, shared: true do
+  describe "raises on type errors" do
+    it "raises a TypeError if passed nil" do
+      -> { "abc".send(@method, nil) }.should.raise(TypeError, "no implicit conversion of nil into String")
+    end
+
+    it "raises a TypeError if passed a boolean" do
+      -> { "abc".send(@method, true) }.should.raise(TypeError, "no implicit conversion of true into String")
+    end
+
+    it "raises a TypeError if passed a Symbol" do
+      not_supported_on :opal do
+        -> { "abc".send(@method, :a) }.should.raise(TypeError, "no implicit conversion of Symbol into String")
+      end
+    end
+
+    it "raises a TypeError if passed a Symbol" do
+      obj = mock('x')
+      obj.should_not_receive(:to_int)
+      -> { "hello".send(@method, obj) }.should.raise(TypeError, "no implicit conversion of MockObject into String")
+    end
+
+    it "raises a TypeError if passed an Integer" do
+      -> { "abc".send(@method, 97) }.should.raise(TypeError, "no implicit conversion of Integer into String")
+    end
+  end
+
+  describe "with multibyte codepoints" do
+    it "raises an IndexError when byte offset lands in the middle of a multibyte character" do
+      -> { "わ".send(@method, "", 1) }.should.raise(IndexError, "offset 1 does not land on character boundary")
+      -> { "わ".send(@method, "", 2) }.should.raise(IndexError, "offset 2 does not land on character boundary")
+      -> { "わ".send(@method, "", -1) }.should.raise(IndexError, "offset 2 does not land on character boundary")
+      -> { "わ".send(@method, "", -2) }.should.raise(IndexError, "offset 1 does not land on character boundary")
+    end
+
+    it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
+      re = Regexp.new "れ".encode(Encoding::EUC_JP)
+      -> do
+        "あれ".send(@method, re)
+      end.should.raise(Encoding::CompatibilityError, "incompatible encoding regexp match (EUC-JP regexp with UTF-8 string)")
+    end
+  end
+
+  describe "with global variables" do
+    it "doesn't set $~ for non regex search" do
+      $~ = nil
+
+      'hello.'.send(@method, 'll')
+      $~.should == nil
+    end
+
+    it "sets $~ to MatchData of match and nil when there's none" do
+      'hello.'.send(@method, /.e./)
+      $~[0].should == 'hel'
+
+      'hello.'.send(@method, /not/)
+      $~.should == nil
+    end
+  end
+end
diff --git a/spec/ruby/core/string/shared/chars.rb b/spec/ruby/core/string/shared/chars.rb
index c8716521bd..826d403589 100644
--- a/spec/ruby/core/string/shared/chars.rb
+++ b/spec/ruby/core/string/shared/chars.rb
@@ -11,22 +11,21 @@ describe :string_chars, shared: true do
 
   it "returns self" do
     s = StringSpecs::MyString.new "hello"
-    s.send(@method){}.should equal(s)
+    s.send(@method){}.should.equal?(s)
   end
 
-
   it "is unicode aware" do
     "\303\207\342\210\202\303\251\306\222g".send(@method).to_a.should ==
       ["\303\207", "\342\210\202", "\303\251", "\306\222", "g"]
   end
 
   it "returns characters in the same encoding as self" do
-    "&%".force_encoding('Shift_JIS').send(@method).to_a.all? {|c| c.encoding.name.should == 'Shift_JIS'}
+    "&%".dup.force_encoding('Shift_JIS').send(@method).to_a.all? {|c| c.encoding.name.should == 'Shift_JIS'}
     "&%".encode('BINARY').send(@method).to_a.all? {|c| c.encoding.should == Encoding::BINARY }
   end
 
   it "works with multibyte characters" do
-    s = "\u{8987}".force_encoding("UTF-8")
+    s = "\u{8987}".dup.force_encoding("UTF-8")
     s.bytesize.should == 3
     s.send(@method).to_a.should == [s]
   end
@@ -34,19 +33,19 @@ describe :string_chars, shared: true do
   it "works if the String's contents is invalid for its encoding" do
     xA4 = [0xA4].pack('C')
     xA4.force_encoding('UTF-8')
-    xA4.valid_encoding?.should be_false
+    xA4.valid_encoding?.should == false
     xA4.send(@method).to_a.should == [xA4.force_encoding("UTF-8")]
   end
 
   it "returns a different character if the String is transcoded" do
-    s = "\u{20AC}".force_encoding('UTF-8')
-    s.encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
+    s = "\u{20AC}".dup.force_encoding('UTF-8')
+    s.encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".dup.force_encoding('UTF-8')]
     s.encode('iso-8859-15').send(@method).to_a.should == [[0xA4].pack('C').force_encoding('iso-8859-15')]
-    s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
+    s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".dup.force_encoding('UTF-8')]
   end
 
   it "uses the String's encoding to determine what characters it contains" do
-    s = "\u{24B62}"
+    s = +"\u{24B62}"
 
     s.force_encoding('UTF-8').send(@method).to_a.should == [
       s.force_encoding('UTF-8')
@@ -64,15 +63,24 @@ describe :string_chars, shared: true do
     ]
   end
 
-  it "taints resulting strings when self is tainted" do
-    str = "hello"
+  it "returns individual chars for dummy encodings" do
+    "ab".dup.force_encoding(Encoding::UTF_7).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_7),
+      "\x62".dup.force_encoding(Encoding::UTF_7)
+    ]
 
-    str.send(@method) do |x|
-      x.tainted?.should == false
-    end
+    "abcd".dup.force_encoding(Encoding::UTF_16).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_16),
+      "\x62".dup.force_encoding(Encoding::UTF_16),
+      "\x63".dup.force_encoding(Encoding::UTF_16),
+      "\x64".dup.force_encoding(Encoding::UTF_16)
+    ]
 
-    str.dup.taint.send(@method) do |x|
-      x.tainted?.should == true
-    end
+    "abcd".dup.force_encoding(Encoding::UTF_32).send(@method).to_a.should == [
+      "\x61".dup.force_encoding(Encoding::UTF_32),
+      "\x62".dup.force_encoding(Encoding::UTF_32),
+      "\x63".dup.force_encoding(Encoding::UTF_32),
+      "\x64".dup.force_encoding(Encoding::UTF_32)
+    ]
   end
 end
diff --git a/spec/ruby/core/string/shared/codepoints.rb b/spec/ruby/core/string/shared/codepoints.rb
index e94a57f48e..b6abf6a3ff 100644
--- a/spec/ruby/core/string/shared/codepoints.rb
+++ b/spec/ruby/core/string/shared/codepoints.rb
@@ -1,15 +1,15 @@
-# -*- encoding: binary -*-
+# encoding: binary
 describe :string_codepoints, shared: true do
   it "returns self" do
     s = "foo"
     result = s.send(@method) {}
-    result.should equal s
+    result.should.equal? s
   end
 
   it "raises an ArgumentError when self has an invalid encoding and a method is called on the returned Enumerator" do
-    s = "\xDF".force_encoding(Encoding::UTF_8)
-    s.valid_encoding?.should be_false
-    -> { s.send(@method).to_a }.should raise_error(ArgumentError)
+    s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.send(@method).to_a }.should.raise(ArgumentError)
   end
 
   it "yields each codepoint to the block if one is given" do
@@ -21,14 +21,14 @@ describe :string_codepoints, shared: true do
   end
 
   it "raises an ArgumentError if self's encoding is invalid and a block is given" do
-    s = "\xDF".force_encoding(Encoding::UTF_8)
-    s.valid_encoding?.should be_false
-    -> { s.send(@method) { } }.should raise_error(ArgumentError)
+    s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should == false
+    -> { s.send(@method) { } }.should.raise(ArgumentError)
   end
 
-  it "yields codepoints as Fixnums" do
+  it "yields codepoints as Integers" do
     "glark\u{20}".send(@method).to_a.each do |codepoint|
-      codepoint.should be_an_instance_of(Fixnum)
+      codepoint.should.instance_of?(Integer)
     end
   end
 
@@ -49,14 +49,19 @@ describe :string_codepoints, shared: true do
 
   it "round-trips to the original String using Integer#chr" do
     s = "\u{13}\u{7711}\u{1010}"
-    s2 = ""
+    s2 = +""
     s.send(@method) {|n| s2 << n.chr(Encoding::UTF_8)}
     s.should == s2
   end
 
   it "is synonymous with #bytes for Strings which are single-byte optimizable" do
     s = "(){}".encode('ascii')
-    s.ascii_only?.should be_true
+    s.ascii_only?.should == true
     s.send(@method).to_a.should == s.bytes.to_a
   end
+
+  it "returns individual bytes for dummy encodings UTF-16 and UTF-32" do
+    "abcd".dup.force_encoding(Encoding::UTF_16).send(@method).to_a.should == [97, 98, 99, 100]
+    "abcd".dup.force_encoding(Encoding::UTF_32).send(@method).to_a.should == [97, 98, 99, 100]
+  end
 end
diff --git a/spec/ruby/core/string/shared/concat.rb b/spec/ruby/core/string/shared/concat.rb
index 53a8bc23fb..60cd0e12d4 100644
--- a/spec/ruby/core/string/shared/concat.rb
+++ b/spec/ruby/core/string/shared/concat.rb
@@ -1,52 +1,31 @@
+# frozen_string_literal: false
 describe :string_concat, shared: true do
   it "concatenates the given argument to self and returns self" do
     str = 'hello '
-    str.send(@method, 'world').should equal(str)
+    str.send(@method, 'world').should.equal?(str)
     str.should == "hello world"
   end
 
-  it "converts the given argument to a String using to_str" do
-    obj = mock('world!')
-    obj.should_receive(:to_str).and_return("world!")
-    a = 'hello '.send(@method, obj)
-    a.should == 'hello world!'
-  end
-
-  it "raises a TypeError if the given argument can't be converted to a String" do
-    -> { 'hello '.send(@method, [])        }.should raise_error(TypeError)
-    -> { 'hello '.send(@method, mock('x')) }.should raise_error(TypeError)
-  end
-
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     a = "hello"
     a.freeze
 
-    -> { a.send(@method, "")     }.should raise_error(frozen_error_class)
-    -> { a.send(@method, "test") }.should raise_error(frozen_error_class)
+    -> { a.send(@method, "")     }.should.raise(FrozenError)
+    -> { a.send(@method, "test") }.should.raise(FrozenError)
   end
 
   it "returns a String when given a subclass instance" do
     a = "hello"
     a.send(@method, StringSpecs::MyString.new(" world"))
     a.should == "hello world"
-    a.should be_an_instance_of(String)
+    a.should.instance_of?(String)
   end
 
   it "returns an instance of same class when called on a subclass" do
     str = StringSpecs::MyString.new("hello")
     str.send(@method, " world")
     str.should == "hello world"
-    str.should be_an_instance_of(StringSpecs::MyString)
-  end
-
-  it "taints self if other is tainted" do
-    "x".send(@method, "".taint).tainted?.should == true
-    "x".send(@method, "y".taint).tainted?.should == true
-  end
-
-  it "untrusts self if other is untrusted" do
-    "x".send(@method, "".untrust).untrusted?.should == true
-    "x".send(@method, "y".untrust).untrusted?.should == true
+    str.should.instance_of?(StringSpecs::MyString)
   end
 
   describe "with Integer" do
@@ -71,28 +50,28 @@ describe :string_concat, shared: true do
     end
 
     it "raises RangeError if the argument is an invalid codepoint for self's encoding" do
-      -> { "".encode(Encoding::US_ASCII).send(@method, 256) }.should raise_error(RangeError)
-      -> { "".encode(Encoding::EUC_JP).send(@method, 0x81)  }.should raise_error(RangeError)
+      -> { "".encode(Encoding::US_ASCII).send(@method, 256) }.should.raise(RangeError)
+      -> { "".encode(Encoding::EUC_JP).send(@method, 0x81)  }.should.raise(RangeError)
     end
 
     it "raises RangeError if the argument is negative" do
-      -> { "".send(@method, -200)          }.should raise_error(RangeError)
-      -> { "".send(@method, -bignum_value) }.should raise_error(RangeError)
+      -> { "".send(@method, -200)          }.should.raise(RangeError)
+      -> { "".send(@method, -bignum_value) }.should.raise(RangeError)
     end
 
     it "doesn't call to_int on its argument" do
       x = mock('x')
       x.should_not_receive(:to_int)
 
-      -> { "".send(@method, x) }.should raise_error(TypeError)
+      -> { "".send(@method, x) }.should.raise(TypeError)
     end
 
-    it "raises a #{frozen_error_class} when self is frozen" do
+    it "raises a FrozenError when self is frozen" do
       a = "hello"
       a.freeze
 
-      -> { a.send(@method, 0)  }.should raise_error(frozen_error_class)
-      -> { a.send(@method, 33) }.should raise_error(frozen_error_class)
+      -> { a.send(@method, 0)  }.should.raise(FrozenError)
+      -> { a.send(@method, 33) }.should.raise(FrozenError)
     end
   end
 end
@@ -112,7 +91,7 @@ describe :string_concat_encoding, shared: true do
     end
 
     it "raises Encoding::CompatibilityError if neither are empty" do
-      -> { "x".encode("UTF-16LE").send(@method, "y".encode("UTF-8")) }.should raise_error(Encoding::CompatibilityError)
+      -> { "x".encode("UTF-16LE").send(@method, "y".encode("UTF-8")) }.should.raise(Encoding::CompatibilityError)
     end
   end
 
@@ -130,7 +109,7 @@ describe :string_concat_encoding, shared: true do
     end
 
     it "raises Encoding::CompatibilityError if neither are empty" do
-      -> { "x".encode("UTF-8").send(@method, "y".encode("UTF-16LE")) }.should raise_error(Encoding::CompatibilityError)
+      -> { "x".encode("UTF-8").send(@method, "y".encode("UTF-16LE")) }.should.raise(Encoding::CompatibilityError)
     end
   end
 
@@ -148,7 +127,7 @@ describe :string_concat_encoding, shared: true do
     end
 
     it "raises Encoding::CompatibilityError if neither are ASCII-only" do
-      -> { "\u00E9".encode("UTF-8").send(@method, "\u00E9".encode("ISO-8859-1")) }.should raise_error(Encoding::CompatibilityError)
+      -> { "\u00E9".encode("UTF-8").send(@method, "\u00E9".encode("ISO-8859-1")) }.should.raise(Encoding::CompatibilityError)
     end
   end
 
@@ -158,3 +137,23 @@ describe :string_concat_encoding, shared: true do
     end
   end
 end
+
+describe :string_concat_type_coercion, shared: true do
+  it "converts the given argument to a String using to_str" do
+    obj = mock('world!')
+    obj.should_receive(:to_str).and_return("world!")
+    a = 'hello '.send(@method, obj)
+    a.should == 'hello world!'
+  end
+
+  it "raises a TypeError if the given argument can't be converted to a String" do
+    -> { 'hello '.send(@method, [])        }.should.raise(TypeError)
+    -> { 'hello '.send(@method, mock('x')) }.should.raise(TypeError)
+  end
+
+  it "raises a NoMethodError if the given argument raises a NoMethodError during type coercion to a String" do
+    obj = mock('world!')
+    obj.should_receive(:to_str).and_raise(NoMethodError)
+    -> { 'hello '.send(@method, obj) }.should.raise(NoMethodError)
+  end
+end
diff --git a/spec/ruby/core/string/shared/dedup.rb b/spec/ruby/core/string/shared/dedup.rb
new file mode 100644
index 0000000000..59506c2901
--- /dev/null
+++ b/spec/ruby/core/string/shared/dedup.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: false
+describe :string_dedup, shared: true do
+  it 'returns self if the String is frozen' do
+    input  = 'foo'.freeze
+    output = input.send(@method)
+
+    output.should.equal?(input)
+    output.should.frozen?
+  end
+
+  it 'returns a frozen copy if the String is not frozen' do
+    input  = 'foo'
+    output = input.send(@method)
+
+    output.should.frozen?
+    output.should_not.equal?(input)
+    output.should == 'foo'
+  end
+
+  it "returns the same object for equal unfrozen strings" do
+    origin = "this is a string"
+    dynamic = %w(this is a string).join(' ')
+
+    origin.should_not.equal?(dynamic)
+    origin.send(@method).should.equal?(dynamic.send(@method))
+  end
+
+  it "returns the same object when it's called on the same String literal" do
+    "unfrozen string".send(@method).should.equal?("unfrozen string".send(@method))
+    "unfrozen string".send(@method).should_not.equal?("another unfrozen string".send(@method))
+  end
+
+  it "deduplicates frozen strings" do
+    dynamic = %w(this string is frozen).join(' ').freeze
+
+    dynamic.should_not.equal?("this string is frozen".freeze)
+
+    dynamic.send(@method).should.equal?("this string is frozen".freeze)
+    dynamic.send(@method).should.equal?("this string is frozen".send(@method).freeze)
+  end
+
+  it "does not deduplicate a frozen string when it has instance variables" do
+    dynamic = %w(this string is frozen).join(' ')
+    dynamic.instance_variable_set(:@a, 1)
+    dynamic.freeze
+
+    dynamic.send(@method).should_not.equal?("this string is frozen".freeze)
+    dynamic.send(@method).should_not.equal?("this string is frozen".send(@method).freeze)
+    dynamic.send(@method).should.equal?(dynamic)
+  end
+end
diff --git a/spec/ruby/core/string/shared/each_char_without_block.rb b/spec/ruby/core/string/shared/each_char_without_block.rb
index 397100ce0e..3c32bae42b 100644
--- a/spec/ruby/core/string/shared/each_char_without_block.rb
+++ b/spec/ruby/core/string/shared/each_char_without_block.rb
@@ -6,7 +6,7 @@ describe :string_each_char_without_block, shared: true do
   describe "when no block is given" do
     it "returns an enumerator" do
       enum = "hello".send(@method)
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.to_a.should == ['h', 'e', 'l', 'l', 'o']
     end
 
diff --git a/spec/ruby/core/string/shared/each_codepoint_without_block.rb b/spec/ruby/core/string/shared/each_codepoint_without_block.rb
index 92b7f76032..60d603954c 100644
--- a/spec/ruby/core/string/shared/each_codepoint_without_block.rb
+++ b/spec/ruby/core/string/shared/each_codepoint_without_block.rb
@@ -1,14 +1,14 @@
-# -*- encoding: binary -*-
+# encoding: binary
 describe :string_each_codepoint_without_block, shared: true do
   describe "when no block is given" do
     it "returns an Enumerator" do
-      "".send(@method).should be_an_instance_of(Enumerator)
+      "".send(@method).should.instance_of?(Enumerator)
     end
 
     it "returns an Enumerator even when self has an invalid encoding" do
-      s = "\xDF".force_encoding(Encoding::UTF_8)
-      s.valid_encoding?.should be_false
-      s.send(@method).should be_an_instance_of(Enumerator)
+      s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+      s.valid_encoding?.should == false
+      s.send(@method).should.instance_of?(Enumerator)
     end
 
     describe "returned Enumerator" do
@@ -23,8 +23,8 @@ describe :string_each_codepoint_without_block, shared: true do
         end
 
         it "should return the size of the string even when the string has an invalid encoding" do
-          s = "\xDF".force_encoding(Encoding::UTF_8)
-          s.valid_encoding?.should be_false
+          s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+          s.valid_encoding?.should == false
           s.send(@method).size.should == 1
         end
       end
diff --git a/spec/ruby/core/string/shared/each_line.rb b/spec/ruby/core/string/shared/each_line.rb
index 241a90eee3..127db876ad 100644
--- a/spec/ruby/core/string/shared/each_line.rb
+++ b/spec/ruby/core/string/shared/each_line.rb
@@ -40,39 +40,41 @@ describe :string_each_line, shared: true do
     b.should == ["foo\n", "🤡🤡🤡🤡🤡🤡🤡\n", "bar\n", "baz\n"]
   end
 
-  it "taints substrings that are passed to the block if self is tainted" do
-    "one\ntwo\r\nthree".taint.send(@method) { |s| s.tainted?.should == true }
-
-    "x.y.".send(@method, ".".taint) { |s| s.tainted?.should == false }
-  end
-
   it "passes self as a whole to the block if the separator is nil" do
     a = []
     "one\ntwo\r\nthree".send(@method, nil) { |s| a << s }
     a.should == ["one\ntwo\r\nthree"]
   end
 
-  ruby_version_is ''...'2.5' do
-    it "yields paragraphs (broken by 2 or more successive newlines) when passed ''" do
+  context "when passed '' (paragraph mode, broken by 2 or more successive newlines)" do
+    it "replaces multiple newlines with only two ones" do
       a = []
       "hello\nworld\n\n\nand\nuniverse\n\n\n\n\n".send(@method, '') { |s| a << s }
-      a.should == ["hello\nworld\n\n\n", "and\nuniverse\n\n\n\n\n"]
+      a.should == ["hello\nworld\n\n", "and\nuniverse\n\n"]
 
       a = []
       "hello\nworld\n\n\nand\nuniverse\n\n\n\n\ndog".send(@method, '') { |s| a << s }
-      a.should == ["hello\nworld\n\n\n", "and\nuniverse\n\n\n\n\n", "dog"]
+      a.should == ["hello\nworld\n\n", "and\nuniverse\n\n", "dog"]
     end
-  end
 
-  ruby_version_is '2.5' do
-    it "yields paragraphs (broken by 2 or more successive newlines) when passed '' and replaces multiple newlines with only two ones" do
+    it 'handles \r\n-style newlines' do
       a = []
-      "hello\nworld\n\n\nand\nuniverse\n\n\n\n\n".send(@method, '') { |s| a << s }
-      a.should == ["hello\nworld\n\n", "and\nuniverse\n\n"]
+      "hello\nworld\r\n\r\n\nand\nuniverse\n\r\n\n\n\n".send(@method, '') { |s| a << s }
+      a.should == ["hello\nworld\r\n\r\n", "and\nuniverse\n\r\n"]
 
       a = []
-      "hello\nworld\n\n\nand\nuniverse\n\n\n\n\ndog".send(@method, '') { |s| a << s }
-      a.should == ["hello\nworld\n\n", "and\nuniverse\n\n", "dog"]
+      "hello\r\nworld\n\n\nand\nuniverse\n\n\n\r\n\r\ndog".send(@method, '') { |s| a << s }
+      a.should == ["hello\r\nworld\n\n", "and\nuniverse\n\n", "dog"]
+    end
+
+    it "removes trailing newlines with `chomp: true`" do
+      a = []
+      "hello\nworld\n\n\nand\nuniverse\n\n\n\n\n".send(@method, '', chomp: true) { |s| a << s }
+      a.should == ["hello\nworld", "and\nuniverse"]
+
+      a = []
+      "hello\nworld\n\n\nand\nuniverse\n\n\n\n\ndog".send(@method, '', chomp: true) { |s| a << s }
+      a.should == ["hello\nworld", "and\nuniverse", "dog"]
     end
   end
 
@@ -82,7 +84,7 @@ describe :string_each_line, shared: true do
     end
 
     after :each do
-      $/ = @before_separator
+      suppress_warning {$/ = @before_separator}
     end
 
     it "as the separator when none is given" do
@@ -94,10 +96,10 @@ describe :string_each_line, shared: true do
           expected = []
           str.send(@method, sep) { |x| expected << x }
 
-          $/ = sep
+          suppress_warning {$/ = sep}
 
           actual = []
-          str.send(@method) { |x| actual << x }
+          suppress_warning {str.send(@method) { |x| actual << x }}
 
           actual.should == expected
         end
@@ -105,15 +107,15 @@ describe :string_each_line, shared: true do
     end
   end
 
-  it "yields subclass instances for subclasses" do
+  it "yields String instances for subclasses" do
     a = []
     StringSpecs::MyString.new("hello\nworld").send(@method) { |s| a << s.class }
-    a.should == [StringSpecs::MyString, StringSpecs::MyString]
+    a.should == [String, String]
   end
 
   it "returns self" do
     s = "hello\nworld"
-    (s.send(@method) {}).should equal(s)
+    (s.send(@method) {}).should.equal?(s)
   end
 
   it "tries to convert the separator to a string using to_str" do
@@ -126,15 +128,21 @@ describe :string_each_line, shared: true do
   end
 
   it "does not care if the string is modified while substituting" do
-    str = "hello\nworld."
+    str = +"hello\nworld."
     out = []
     str.send(@method){|x| out << x; str[-1] = '!' }.should == "hello\nworld!"
     out.should == ["hello\n", "world."]
   end
 
+  it "returns Strings in the same encoding as self" do
+    "one\ntwo\r\nthree".encode("US-ASCII").send(@method) do |s|
+      s.encoding.should == Encoding::US_ASCII
+    end
+  end
+
   it "raises a TypeError when the separator can't be converted to a string" do
-    -> { "hello world".send(@method, false) {}     }.should raise_error(TypeError)
-    -> { "hello world".send(@method, mock('x')) {} }.should raise_error(TypeError)
+    -> { "hello world".send(@method, false) {}     }.should.raise(TypeError)
+    -> { "hello world".send(@method, mock('x')) {} }.should.raise(TypeError)
   end
 
   it "accepts a string separator" do
@@ -142,7 +150,7 @@ describe :string_each_line, shared: true do
   end
 
   it "raises a TypeError when the separator is a symbol" do
-    -> { "hello world".send(@method, :o).to_a }.should raise_error(TypeError)
+    -> { "hello world".send(@method, :o).to_a }.should.raise(TypeError)
   end
 
   context "when `chomp` keyword argument is passed" do
@@ -173,4 +181,18 @@ describe :string_each_line, shared: true do
       a.should == ["hello\r\n", "world\r\n"]
     end
   end
+
+  it "does not split lines for dummy UTF-16" do
+    "a\nb".encode(Encoding::UTF_16).lines.should == [
+      "\xFE\xFF\x00\x61\x00\n\x00\x62".dup.force_encoding(Encoding::UTF_16)
+    ]
+
+    str = "\x00\n\n\x00".dup.force_encoding(Encoding::UTF_16)
+    str.lines.should == [str]
+  end
+
+  it "raises Encoding::ConverterNotFoundError for dummy UTF-7" do
+    str = "a\nb".dup.force_encoding(Encoding::UTF_7)
+    -> { str.lines }.should.raise(Encoding::ConverterNotFoundError)
+  end
 end
diff --git a/spec/ruby/core/string/shared/each_line_without_block.rb b/spec/ruby/core/string/shared/each_line_without_block.rb
index 8e08b0390c..af0ab69c00 100644
--- a/spec/ruby/core/string/shared/each_line_without_block.rb
+++ b/spec/ruby/core/string/shared/each_line_without_block.rb
@@ -2,7 +2,7 @@ describe :string_each_line_without_block, shared: true do
   describe "when no block is given" do
     it "returns an enumerator" do
       enum = "hello world".send(@method, ' ')
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.to_a.should == ["hello ", "world"]
     end
 
diff --git a/spec/ruby/core/string/shared/encode.rb b/spec/ruby/core/string/shared/encode.rb
index a73de5b943..7f644c26d9 100644
--- a/spec/ruby/core/string/shared/encode.rb
+++ b/spec/ruby/core/string/shared/encode.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 describe :string_encode, shared: true do
   describe "when passed no options" do
     it "transcodes to Encoding.default_internal when set" do
@@ -10,7 +11,7 @@ describe :string_encode, shared: true do
     it "transcodes a 7-bit String despite no generic converting being available" do
       -> do
         Encoding::Converter.new Encoding::Emacs_Mule, Encoding::BINARY
-      end.should raise_error(Encoding::ConverterNotFoundError)
+      end.should.raise(Encoding::ConverterNotFoundError)
 
       Encoding.default_internal = Encoding::Emacs_Mule
       str = "\x79".force_encoding Encoding::BINARY
@@ -21,7 +22,7 @@ describe :string_encode, shared: true do
     it "raises an Encoding::ConverterNotFoundError when no conversion is possible" do
       Encoding.default_internal = Encoding::Emacs_Mule
       str = [0x80].pack('C').force_encoding Encoding::BINARY
-      -> { str.send(@method) }.should raise_error(Encoding::ConverterNotFoundError)
+      -> { str.send(@method) }.should.raise(Encoding::ConverterNotFoundError)
     end
   end
 
@@ -53,7 +54,7 @@ describe :string_encode, shared: true do
     it "transcodes a 7-bit String despite no generic converting being available" do
       -> do
         Encoding::Converter.new Encoding::Emacs_Mule, Encoding::BINARY
-      end.should raise_error(Encoding::ConverterNotFoundError)
+      end.should.raise(Encoding::ConverterNotFoundError)
 
       str = "\x79".force_encoding Encoding::BINARY
       str.send(@method, Encoding::Emacs_Mule).should == "y".force_encoding(Encoding::BINARY)
@@ -63,13 +64,21 @@ describe :string_encode, shared: true do
       str = [0x80].pack('C').force_encoding Encoding::BINARY
       -> do
         str.send(@method, Encoding::Emacs_Mule)
-      end.should raise_error(Encoding::ConverterNotFoundError)
+      end.should.raise(Encoding::ConverterNotFoundError)
     end
 
     it "raises an Encoding::ConverterNotFoundError for an invalid encoding" do
       -> do
         "abc".send(@method, "xyz")
-      end.should raise_error(Encoding::ConverterNotFoundError)
+      end.should.raise(Encoding::ConverterNotFoundError)
+    end
+
+    it "raises an Encoding::UndefinedConversionError when a character cannot be represented in the destination encoding" do
+      # U+0100 (Ā) is valid UTF-8 but not representable in windows-1252
+      str = "test\u0100".force_encoding('utf-8')
+      -> {
+        str.send(@method, Encoding::Windows_1252)
+      }.should.raise(Encoding::UndefinedConversionError)
     end
   end
 
@@ -98,7 +107,7 @@ describe :string_encode, shared: true do
       str = [0x80].pack('C').force_encoding Encoding::BINARY
       -> do
         str.send(@method, invalid: :replace, undef: :replace)
-      end.should raise_error(Encoding::ConverterNotFoundError)
+      end.should.raise(Encoding::ConverterNotFoundError)
     end
 
     it "replaces invalid characters when replacing Emacs-Mule encoded strings" do
@@ -141,6 +150,14 @@ describe :string_encode, shared: true do
       "ab#{xFF}c".send(@method, Encoding::ISO_8859_1, invalid: :replace).should == "ab?c"
     end
 
+    it "raises UndefinedConversionError for characters not representable in destination encoding with only invalid: :replace" do
+      # U+0100 (Ā) is valid UTF-8 but not representable in windows-1252
+      str = "test\u0100".force_encoding('utf-8')
+      -> {
+        str.send(@method, Encoding::Windows_1252, invalid: :replace, replace: "")
+      }.should.raise(Encoding::UndefinedConversionError)
+    end
+
     it "calls #to_hash to convert the options object" do
       options = mock("string encode options")
       options.should_receive(:to_hash).and_return({ undef: :replace })
@@ -193,6 +210,190 @@ describe :string_encode, shared: true do
     end
   end
 
+  describe "given the fallback option" do
+    context "given a hash" do
+      it "looks up the replacement value from the hash" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: { "\ufffd" => "bar" })
+        encoded.should == "Bbar"
+      end
+
+      it "calls to_str on the returned value" do
+        obj = Object.new
+        obj.should_receive(:to_str).and_return("bar")
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: { "\ufffd" => obj })
+        encoded.should == "Bbar"
+      end
+
+      it "does not call to_s on the returned value" do
+        obj = Object.new
+        obj.should_not_receive(:to_s)
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: { "\ufffd" => obj })
+        }.should.raise(TypeError, "no implicit conversion of Object into String")
+      end
+
+      it "raises an error if the key is not present in the hash" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: { "foo" => "bar" })
+        }.should.raise(Encoding::UndefinedConversionError, "U+FFFD from UTF-8 to US-ASCII")
+      end
+
+      it "raises an error if the value is itself invalid" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: { "\ufffd" => "\uffee" })
+        }.should.raise(ArgumentError, "too big fallback string")
+      end
+
+      it "uses the hash's default value if set" do
+        hash = {}
+        hash.default = "bar"
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: hash)
+        encoded.should == "Bbar"
+      end
+
+      it "uses the result of calling default_proc if set" do
+        hash = {}
+        hash.default_proc = -> _, _ { "bar" }
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: hash)
+        encoded.should == "Bbar"
+      end
+    end
+
+    context "given an object inheriting from Hash" do
+      before do
+        klass = Class.new(Hash)
+        @hash_like = klass.new
+        @hash_like["\ufffd"] = "bar"
+      end
+
+      it "looks up the replacement value from the object" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: @hash_like)
+        encoded.should == "Bbar"
+      end
+    end
+
+    context "given an object responding to []" do
+      before do
+        klass = Class.new do
+          def [](c) = c.bytes.inspect
+        end
+        @hash_like = klass.new
+      end
+
+      it "calls [] on the object, passing the invalid character" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: @hash_like)
+        encoded.should == "B[239, 191, 189]"
+      end
+    end
+
+    context "given an object not responding to []" do
+      before do
+        @non_hash_like = Object.new
+      end
+
+      it "raises an error" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: @non_hash_like)
+        }.should.raise(Encoding::UndefinedConversionError, "U+FFFD from UTF-8 to US-ASCII")
+      end
+    end
+
+    context "given a proc" do
+      it "calls the proc to get the replacement value, passing in the invalid character" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: proc { |c| c.bytes.inspect })
+        encoded.should == "B[239, 191, 189]"
+      end
+
+      it "calls to_str on the returned value" do
+        obj = Object.new
+        obj.should_receive(:to_str).and_return("bar")
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: proc { |c| obj })
+        encoded.should == "Bbar"
+      end
+
+      it "does not call to_s on the returned value" do
+        obj = Object.new
+        obj.should_not_receive(:to_s)
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: proc { |c| obj })
+        }.should.raise(TypeError, "no implicit conversion of Object into String")
+      end
+
+      it "raises an error if the returned value is itself invalid" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: -> c { "\uffee" })
+        }.should.raise(ArgumentError, "too big fallback string")
+      end
+    end
+
+    context "given a lambda" do
+      it "calls the lambda to get the replacement value, passing in the invalid character" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: -> c { c.bytes.inspect })
+        encoded.should == "B[239, 191, 189]"
+      end
+
+      it "calls to_str on the returned value" do
+        obj = Object.new
+        obj.should_receive(:to_str).and_return("bar")
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: -> c { obj })
+        encoded.should == "Bbar"
+      end
+
+      it "does not call to_s on the returned value" do
+        obj = Object.new
+        obj.should_not_receive(:to_s)
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: -> c { obj })
+        }.should.raise(TypeError, "no implicit conversion of Object into String")
+      end
+
+      it "raises an error if the returned value is itself invalid" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: -> c { "\uffee" })
+        }.should.raise(ArgumentError, "too big fallback string")
+      end
+    end
+
+    context "given a method" do
+      def replace(c) = c.bytes.inspect
+      def replace_bad(c) = "\uffee"
+
+      def replace_to_str(c)
+        obj = Object.new
+        obj.should_receive(:to_str).and_return("bar")
+        obj
+      end
+
+      def replace_to_s(c)
+        obj = Object.new
+        obj.should_not_receive(:to_s)
+        obj
+      end
+
+      it "calls the method to get the replacement value, passing in the invalid character" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: method(:replace))
+        encoded.should == "B[239, 191, 189]"
+      end
+
+      it "calls to_str on the returned value" do
+        encoded = "B\ufffd".encode(Encoding::US_ASCII, fallback: method(:replace_to_str))
+        encoded.should == "Bbar"
+      end
+
+      it "does not call to_s on the returned value" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: method(:replace_to_s))
+        }.should.raise(TypeError, "no implicit conversion of Object into String")
+      end
+
+      it "raises an error if the returned value is itself invalid" do
+        -> {
+          "B\ufffd".encode(Encoding::US_ASCII, fallback: method(:replace_bad))
+        }.should.raise(ArgumentError, "too big fallback string")
+      end
+    end
+  end
+
   describe "given the xml: :text option" do
     it "replaces all instances of '&' with '&amp;'" do
       '& and &'.send(@method, "UTF-8", xml: :text).should == '&amp; and &amp;'
@@ -242,6 +443,6 @@ describe :string_encode, shared: true do
   end
 
   it "raises ArgumentError if the value of the :xml option is not :text or :attr" do
-    -> { ''.send(@method, "UTF-8", xml: :other) }.should raise_error(ArgumentError)
+    -> { ''.send(@method, "UTF-8", xml: :other) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/shared/eql.rb b/spec/ruby/core/string/shared/eql.rb
index 85b861f4f1..0e356c69e8 100644
--- a/spec/ruby/core/string/shared/eql.rb
+++ b/spec/ruby/core/string/shared/eql.rb
@@ -1,34 +1,38 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
 describe :string_eql_value, shared: true do
   it "returns true if self <=> string returns 0" do
-    'hello'.send(@method, 'hello').should be_true
+    'hello'.send(@method, 'hello').should == true
   end
 
   it "returns false if self <=> string does not return 0" do
-    "more".send(@method, "MORE").should be_false
-    "less".send(@method, "greater").should be_false
+    "more".send(@method, "MORE").should == false
+    "less".send(@method, "greater").should == false
   end
 
   it "ignores encoding difference of compatible string" do
-    "hello".force_encoding("utf-8").send(@method, "hello".force_encoding("iso-8859-1")).should be_true
+    "hello".dup.force_encoding("utf-8").send(@method, "hello".dup.force_encoding("iso-8859-1")).should == true
   end
 
   it "considers encoding difference of incompatible string" do
-    "\xff".force_encoding("utf-8").send(@method, "\xff".force_encoding("iso-8859-1")).should be_false
+    "\xff".dup.force_encoding("utf-8").send(@method, "\xff".dup.force_encoding("iso-8859-1")).should == false
   end
 
   it "considers encoding compatibility" do
-    "hello".force_encoding("utf-8").send(@method, "hello".force_encoding("utf-32le")).should be_false
+    "abcd".dup.force_encoding("utf-8").send(@method, "abcd".dup.force_encoding("utf-32le")).should == false
   end
 
   it "ignores subclass differences" do
     a = "hello"
     b = StringSpecs::MyString.new("hello")
 
-    a.send(@method, b).should be_true
-    b.send(@method, a).should be_true
+    a.send(@method, b).should == true
+    b.send(@method, a).should == true
+  end
+
+  it "returns true when comparing 2 empty strings but one is not ASCII-compatible" do
+    "".send(@method, "".dup.force_encoding('iso-2022-jp')).should == true
   end
 end
diff --git a/spec/ruby/core/string/shared/equal_value.rb b/spec/ruby/core/string/shared/equal_value.rb
index fccafb5821..dfc5c7cd29 100644
--- a/spec/ruby/core/string/shared/equal_value.rb
+++ b/spec/ruby/core/string/shared/equal_value.rb
@@ -3,11 +3,11 @@ require_relative '../fixtures/classes'
 
 describe :string_equal_value, shared: true do
   it "returns false if obj does not respond to to_str" do
-    'hello'.send(@method, 5).should be_false
+    'hello'.send(@method, 5).should == false
     not_supported_on :opal do
-      'hello'.send(@method, :hello).should be_false
+      'hello'.send(@method, :hello).should == false
     end
-    'hello'.send(@method, mock('x')).should be_false
+    'hello'.send(@method, mock('x')).should == false
   end
 
   it "returns obj == self if obj responds to to_str" do
@@ -20,10 +20,10 @@ describe :string_equal_value, shared: true do
     # Don't use @method for :== in `obj.should_receive(:==)`
     obj.should_receive(:==).and_return(true)
 
-    'hello'.send(@method, obj).should be_true
+    'hello'.send(@method, obj).should == true
   end
 
   it "is not fooled by NUL characters" do
-    "abc\0def".send(@method, "abc\0xyz").should be_false
+    "abc\0def".send(@method, "abc\0xyz").should == false
   end
 end
diff --git a/spec/ruby/core/string/shared/grapheme_clusters.rb b/spec/ruby/core/string/shared/grapheme_clusters.rb
index 8b666868b1..dd8c7ed5fe 100644
--- a/spec/ruby/core/string/shared/grapheme_clusters.rb
+++ b/spec/ruby/core/string/shared/grapheme_clusters.rb
@@ -9,8 +9,17 @@ describe :string_grapheme_clusters, shared: true do
     a.should == ['a', 'b', "\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}", "\u{1F43E}"]
   end
 
+  it "returns grapheme clusters for various UTF encodings" do
+    [Encoding::UTF_16LE, Encoding::UTF_16BE, Encoding::UTF_32LE, Encoding::UTF_32BE].each do |enc|
+      a = []
+      # test string: abc[rainbow flag emoji][paw prints]
+      "ab\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}\u{1F43E}".encode(enc).send(@method) { |c| a << c }
+      a.should == ['a', 'b', "\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}", "\u{1F43E}"].map { |s| s.encode(enc) }
+    end
+  end
+
   it "returns self" do
     s = StringSpecs::MyString.new "ab\u{1f3f3}\u{fe0f}\u{200d}\u{1f308}\u{1F43E}"
-    s.send(@method) {}.should equal(s)
+    s.send(@method) {}.should.equal?(s)
   end
 end
diff --git a/spec/ruby/core/string/shared/length.rb b/spec/ruby/core/string/shared/length.rb
index f387fb251c..ae572ba755 100644
--- a/spec/ruby/core/string/shared/length.rb
+++ b/spec/ruby/core/string/shared/length.rb
@@ -12,15 +12,44 @@ describe :string_length, shared: true do
 
   it "returns the length of a string in different encodings" do
     utf8_str = 'こにちわ' * 100
-    utf8_str.size.should == 400
-    utf8_str.encode(Encoding::UTF_32BE).size.should == 400
-    utf8_str.encode(Encoding::SHIFT_JIS).size.should == 400
+    utf8_str.send(@method).should == 400
+    utf8_str.encode(Encoding::UTF_32BE).send(@method).should == 400
+    utf8_str.encode(Encoding::SHIFT_JIS).send(@method).should == 400
   end
 
   it "returns the length of the new self after encoding is changed" do
-    str = 'こにちわ'
+    str = +'こにちわ'
     str.send(@method)
 
     str.force_encoding('BINARY').send(@method).should == 12
   end
+
+  it "returns the correct length after force_encoding(BINARY)" do
+    utf8 = "あ"
+    ascii = "a"
+    concat = utf8 + ascii
+
+    concat.encoding.should == Encoding::UTF_8
+    concat.bytesize.should == 4
+
+    concat.send(@method).should == 2
+    concat.force_encoding(Encoding::ASCII_8BIT)
+    concat.send(@method).should == 4
+  end
+
+  it "adds 1 for every invalid byte in UTF-8" do
+    "\xF4\x90\x80\x80".send(@method).should == 4
+    "a\xF4\x90\x80\x80b".send(@method).should == 6
+    "é\xF4\x90\x80\x80è".send(@method).should == 6
+  end
+
+  it "adds 1 (and not 2) for a incomplete surrogate in UTF-16" do
+    "\x00\xd8".dup.force_encoding("UTF-16LE").send(@method).should == 1
+    "\xd8\x00".dup.force_encoding("UTF-16BE").send(@method).should == 1
+  end
+
+  it "adds 1 for a broken sequence in UTF-32" do
+    "\x04\x03\x02\x01".dup.force_encoding("UTF-32LE").send(@method).should == 1
+    "\x01\x02\x03\x04".dup.force_encoding("UTF-32BE").send(@method).should == 1
+  end
 end
diff --git a/spec/ruby/core/string/shared/partition.rb b/spec/ruby/core/string/shared/partition.rb
new file mode 100644
index 0000000000..3f7e606eb3
--- /dev/null
+++ b/spec/ruby/core/string/shared/partition.rb
@@ -0,0 +1,33 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe :string_partition, shared: true do
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("hello").send(@method, "l").each do |item|
+      item.should.instance_of?(String)
+    end
+
+    StringSpecs::MyString.new("hello").send(@method, "x").each do |item|
+      item.should.instance_of?(String)
+    end
+
+    StringSpecs::MyString.new("hello").send(@method, /l./).each do |item|
+      item.should.instance_of?(String)
+    end
+  end
+
+  it "returns before- and after- parts in the same encoding as self" do
+    strings = "hello".encode("US-ASCII").send(@method, "ello")
+    strings[0].encoding.should == Encoding::US_ASCII
+    strings[2].encoding.should == Encoding::US_ASCII
+
+    strings = "hello".encode("US-ASCII").send(@method, /ello/)
+    strings[0].encoding.should == Encoding::US_ASCII
+    strings[2].encoding.should == Encoding::US_ASCII
+  end
+
+  it "returns the matching part in the separator's encoding" do
+    strings = "hello".encode("US-ASCII").send(@method, "ello")
+    strings[1].encoding.should == Encoding::UTF_8
+  end
+end
diff --git a/spec/ruby/core/string/shared/replace.rb b/spec/ruby/core/string/shared/replace.rb
index f13afb3f95..73b26351f1 100644
--- a/spec/ruby/core/string/shared/replace.rb
+++ b/spec/ruby/core/string/shared/replace.rb
@@ -1,7 +1,8 @@
+# frozen_string_literal: false
 describe :string_replace, shared: true do
   it "returns self" do
     a = "a"
-    a.send(@method, "b").should equal(a)
+    a.send(@method, "b").should.equal?(a)
   end
 
   it "replaces the content of self with other" do
@@ -10,34 +11,6 @@ describe :string_replace, shared: true do
     a.should == "another string"
   end
 
-  it "taints self if other is tainted" do
-    a = ""
-    b = "".taint
-    a.send(@method, b)
-    a.tainted?.should == true
-  end
-
-  it "does not untaint self if other is untainted" do
-    a = "".taint
-    b = ""
-    a.send(@method, b)
-    a.tainted?.should == true
-  end
-
-  it "untrusts self if other is untrusted" do
-    a = ""
-    b = "".untrust
-    a.send(@method, b)
-    a.untrusted?.should == true
-  end
-
-  it "does not trust self if other is trusted" do
-    a = "".untrust
-    b = ""
-    a.send(@method, b)
-    a.untrusted?.should == true
-  end
-
   it "replaces the encoding of self with that of other" do
     a = "".encode("UTF-16LE")
     b = "".encode("UTF-8")
@@ -47,7 +20,7 @@ describe :string_replace, shared: true do
 
   it "carries over the encoding invalidity" do
     a = "\u{8765}".force_encoding('ascii')
-    "".send(@method, a).valid_encoding?.should be_false
+    "".send(@method, a).valid_encoding?.should == false
   end
 
   it "tries to convert other to string using to_str" do
@@ -57,19 +30,19 @@ describe :string_replace, shared: true do
   end
 
   it "raises a TypeError if other can't be converted to string" do
-    -> { "hello".send(@method, 123)       }.should raise_error(TypeError)
-    -> { "hello".send(@method, [])        }.should raise_error(TypeError)
-    -> { "hello".send(@method, mock('x')) }.should raise_error(TypeError)
+    -> { "hello".send(@method, 123)       }.should.raise(TypeError)
+    -> { "hello".send(@method, [])        }.should.raise(TypeError)
+    -> { "hello".send(@method, mock('x')) }.should.raise(TypeError)
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
+  it "raises a FrozenError on a frozen instance that is modified" do
     a = "hello".freeze
-    -> { a.send(@method, "world") }.should raise_error(frozen_error_class)
+    -> { a.send(@method, "world") }.should.raise(FrozenError)
   end
 
   # see [ruby-core:23666]
-  it "raises a #{frozen_error_class} on a frozen instance when self-replacing" do
+  it "raises a FrozenError on a frozen instance when self-replacing" do
     a = "hello".freeze
-    -> { a.send(@method, a) }.should raise_error(frozen_error_class)
+    -> { a.send(@method, a) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/shared/slice.rb b/spec/ruby/core/string/shared/slice.rb
index ef7a8787ce..d296ab6680 100644
--- a/spec/ruby/core/string/shared/slice.rb
+++ b/spec/ruby/core/string/shared/slice.rb
@@ -21,17 +21,17 @@ describe :string_slice, shared: true do
   end
 
   it "raises a TypeError if the given index is nil" do
-    -> { "hello".send(@method, nil) }.should raise_error(TypeError)
+    -> { "hello".send(@method, nil) }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the given index can't be converted to an Integer" do
-    -> { "hello".send(@method, mock('x')) }.should raise_error(TypeError)
-    -> { "hello".send(@method, {})        }.should raise_error(TypeError)
-    -> { "hello".send(@method, [])        }.should raise_error(TypeError)
+    -> { "hello".send(@method, mock('x')) }.should.raise(TypeError)
+    -> { "hello".send(@method, {})        }.should.raise(TypeError)
+    -> { "hello".send(@method, [])        }.should.raise(TypeError)
   end
 
   it "raises a RangeError if the index is too big" do
-    -> { "hello".send(@method, bignum_value) }.should raise_error(RangeError)
+    -> { "hello".send(@method, bignum_value) }.should.raise(RangeError)
   end
 end
 
@@ -80,21 +80,12 @@ describe :string_slice_index_length, shared: true do
     "hello there".send(@method, -3,2).should == "er"
   end
 
-  it "always taints resulting strings when self is tainted" do
-    str = "hello world"
-    str.taint
-
-    str.send(@method, 0,0).tainted?.should == true
-    str.send(@method, 0,1).tainted?.should == true
-    str.send(@method, 2,1).tainted?.should == true
-  end
-
-  it "returns a string with the same encoding" do
+  it "returns a string with the same encoding as self" do
     s = "hello there"
     s.send(@method, 1, 9).encoding.should == s.encoding
 
-    a = "hello".force_encoding("binary")
-    b = " there".force_encoding("ISO-8859-1")
+    a = "hello".dup.force_encoding("binary")
+    b = " there".dup.force_encoding("ISO-8859-1")
     c = (a + b).force_encoding(Encoding::US_ASCII)
 
     c.send(@method, 0, 5).encoding.should == Encoding::US_ASCII
@@ -119,6 +110,8 @@ describe :string_slice_index_length, shared: true do
 
     "x".send(@method, -2,0).should == nil
     "x".send(@method, -2,1).should == nil
+
+    "x".send(@method, fixnum_max, 1).should == nil
   end
 
   it "returns nil if the length is negative" do
@@ -126,6 +119,18 @@ describe :string_slice_index_length, shared: true do
     "hello there".send(@method, -4,-3).should == nil
   end
 
+  platform_is pointer_size: 64 do
+    it "returns nil if the length is negative big value" do
+      "hello there".send(@method, 4, -(1 << 31)).should == nil
+
+      # by some reason length < -(1 << 31) on CI on Windows leads to
+      # 'RangeError: bignum too big to convert into `long'' error
+      platform_is_not :windows do
+        "hello there".send(@method, 4, -(1 << 63)).should == nil
+      end
+    end
+  end
+
   it "calls to_int on the given index and the given length" do
     "hello".send(@method, 0.5, 1).should == "h"
     "hello".send(@method, 0.5, 2.5).should == "he"
@@ -140,30 +145,35 @@ describe :string_slice_index_length, shared: true do
   end
 
   it "raises a TypeError when idx or length can't be converted to an integer" do
-    -> { "hello".send(@method, mock('x'), 0) }.should raise_error(TypeError)
-    -> { "hello".send(@method, 0, mock('x')) }.should raise_error(TypeError)
+    -> { "hello".send(@method, mock('x'), 0) }.should.raise(TypeError)
+    -> { "hello".send(@method, 0, mock('x')) }.should.raise(TypeError)
 
     # I'm deliberately including this here.
     # It means that str.send(@method, other, idx) isn't supported.
-    -> { "hello".send(@method, "", 0) }.should raise_error(TypeError)
+    -> { "hello".send(@method, "", 0) }.should.raise(TypeError)
   end
 
   it "raises a TypeError when the given index or the given length is nil" do
-    -> { "hello".send(@method, 1, nil)   }.should raise_error(TypeError)
-    -> { "hello".send(@method, nil, 1)   }.should raise_error(TypeError)
-    -> { "hello".send(@method, nil, nil) }.should raise_error(TypeError)
+    -> { "hello".send(@method, 1, nil)   }.should.raise(TypeError)
+    -> { "hello".send(@method, nil, 1)   }.should.raise(TypeError)
+    -> { "hello".send(@method, nil, nil) }.should.raise(TypeError)
   end
 
   it "raises a RangeError if the index or length is too big" do
-    -> { "hello".send(@method, bignum_value, 1) }.should raise_error(RangeError)
-    -> { "hello".send(@method, 0, bignum_value) }.should raise_error(RangeError)
+    -> { "hello".send(@method, bignum_value, 1) }.should.raise(RangeError)
+    -> { "hello".send(@method, 0, bignum_value) }.should.raise(RangeError)
+  end
+
+  it "raises a RangeError if the index or length is too small" do
+    -> { "hello".send(@method, -bignum_value, 1) }.should.raise(RangeError)
+    -> { "hello".send(@method, 0, -bignum_value) }.should.raise(RangeError)
   end
 
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.send(@method, 0,0).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, 0,4).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, 1,4).should be_an_instance_of(StringSpecs::MyString)
+    s.send(@method, 0,0).should.instance_of?(String)
+    s.send(@method, 0,4).should.instance_of?(String)
+    s.send(@method, 1,4).should.instance_of?(String)
   end
 
   it "handles repeated application" do
@@ -202,6 +212,10 @@ describe :string_slice_range, shared: true do
     "x".send(@method, 1..-1).should == ""
   end
 
+  it "returns a String in the same encoding as self" do
+    "hello there".encode("US-ASCII").send(@method, 1..1).encoding.should == Encoding::US_ASCII
+  end
+
   it "returns nil if the beginning of the range falls outside of self" do
     "hello there".send(@method, 12..-1).should == nil
     "hello there".send(@method, 20..25).should == nil
@@ -234,23 +248,11 @@ describe :string_slice_range, shared: true do
     "x".send(@method, 1...-1).should == ""
   end
 
-  it "always taints resulting strings when self is tainted" do
-    str = "hello world"
-    str.taint
-
-    str.send(@method, 0..0).tainted?.should == true
-    str.send(@method, 0...0).tainted?.should == true
-    str.send(@method, 0..1).tainted?.should == true
-    str.send(@method, 0...1).tainted?.should == true
-    str.send(@method, 2..3).tainted?.should == true
-    str.send(@method, 2..0).tainted?.should == true
-  end
-
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.send(@method, 0...0).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, 0..4).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, 1..4).should be_an_instance_of(StringSpecs::MyString)
+    s.send(@method, 0...0).should.instance_of?(String)
+    s.send(@method, 0..4).should.instance_of?(String)
+    s.send(@method, 1..4).should.instance_of?(String)
   end
 
   it "calls to_int on range arguments" do
@@ -289,6 +291,30 @@ describe :string_slice_range, shared: true do
     "hello world".send(@method, 6..5).send(@method, -1..-1).should == nil
     "hello world".send(@method, 6..5).send(@method, 1..1).should == nil
   end
+
+  it "raises a type error if a range is passed with a length" do
+    ->{ "hello".send(@method, 1..2, 1) }.should.raise(TypeError)
+  end
+
+  it "raises a RangeError if one of the bound is too big" do
+    -> { "hello".send(@method, bignum_value..(bignum_value + 1)) }.should.raise(RangeError)
+    -> { "hello".send(@method, 0..bignum_value) }.should.raise(RangeError)
+  end
+
+  it "works with endless ranges" do
+    "hello there".send(@method, eval("(2..)")).should == "llo there"
+    "hello there".send(@method, eval("(2...)")).should == "llo there"
+    "hello there".send(@method, eval("(-4..)")).should == "here"
+    "hello there".send(@method, eval("(-4...)")).should == "here"
+  end
+
+  it "works with beginless ranges" do
+    "hello there".send(@method, (..5)).should == "hello "
+    "hello there".send(@method, (...5)).should == "hello"
+    "hello there".send(@method, (..-4)).should == "hello th"
+    "hello there".send(@method, (...-4)).should == "hello t"
+    "hello there".send(@method, (...nil)).should == "hello there"
+  end
 end
 
 describe :string_slice_regexp, shared: true do
@@ -301,31 +327,14 @@ describe :string_slice_regexp, shared: true do
     "hello there".send(@method, /xyz/).should == nil
   end
 
-  not_supported_on :opal do
-    it "always taints resulting strings when self or regexp is tainted" do
-      strs = ["hello world"]
-      strs += strs.map { |s| s.dup.taint }
-
-      strs.each do |str|
-        str.send(@method, //).tainted?.should == str.tainted?
-        str.send(@method, /hello/).tainted?.should == str.tainted?
-
-        tainted_re = /./
-        tainted_re.taint
-
-        str.send(@method, tainted_re).tainted?.should == true
-      end
-    end
-
-    it "returns an untrusted string if the regexp is untrusted" do
-      "hello".send(@method, /./.untrust).untrusted?.should be_true
-    end
+  it "returns a String in the same encoding as self" do
+    "hello there".encode("US-ASCII").send(@method, /[aeiou](.)\1/).encoding.should == Encoding::US_ASCII
   end
 
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.send(@method, //).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, /../).should be_an_instance_of(StringSpecs::MyString)
+    s.send(@method, //).should.instance_of?(String)
+    s.send(@method, /../).should.instance_of?(String)
   end
 
   it "sets $~ to MatchData when there is a match and nil when there's none" do
@@ -352,42 +361,28 @@ describe :string_slice_regexp_index, shared: true do
     "har".send(@method, /(.)(.)(.)/, -3).should == "h"
   end
 
-  it "always taints resulting strings when self or regexp is tainted" do
-    strs = ["hello world"]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      str.send(@method, //, 0).tainted?.should == str.tainted?
-      str.send(@method, /hello/, 0).tainted?.should == str.tainted?
-
-      str.send(@method, /(.)(.)(.)/, 0).tainted?.should == str.tainted?
-      str.send(@method, /(.)(.)(.)/, 1).tainted?.should == str.tainted?
-      str.send(@method, /(.)(.)(.)/, -1).tainted?.should == str.tainted?
-      str.send(@method, /(.)(.)(.)/, -2).tainted?.should == str.tainted?
-
-      tainted_re = /(.)(.)(.)/
-      tainted_re.taint
+  it "returns nil if there is no match" do
+    "hello there".send(@method, /(what?)/, 1).should == nil
+  end
 
-      str.send(@method, tainted_re, 0).tainted?.should == true
-      str.send(@method, tainted_re, 1).tainted?.should == true
-      str.send(@method, tainted_re, -1).tainted?.should == true
-    end
+  it "returns nil if the index is larger than the number of captures" do
+    "hello there".send(@method, /hello (.)/, 2).should == nil
+    # You can't refer to 0 using negative indices
+    "hello there".send(@method, /hello (.)/, -2).should == nil
   end
 
-  not_supported_on :opal do
-    it "returns an untrusted string if the regexp is untrusted" do
-      "hello".send(@method, /(.)/.untrust, 1).untrusted?.should be_true
-    end
+  it "returns nil if there is no capture for the given index" do
+    "hello there".send(@method, /[aeiou](.)\1/, 2).should == nil
   end
 
-  it "returns nil if there is no match" do
-    "hello there".send(@method, /(what?)/, 1).should == nil
+  it "returns nil if the given capture group was not matched but still sets $~" do
+    "test".send(@method, /te(z)?/, 1).should == nil
+    $~[0].should == "te"
+    $~[1].should == nil
   end
 
-  it "returns nil if there is no capture for the given index" do
-    "hello there".send(@method, /[aeiou](.)\1/, 2).should == nil
-    # You can't refer to 0 using negative indices
-    "hello there".send(@method, /[aeiou](.)\1/, -2).should == nil
+  it "returns a String in the same encoding as self" do
+    "hello there".encode("US-ASCII").send(@method, /[aeiou](.)\1/, 0).encoding.should == Encoding::US_ASCII
   end
 
   it "calls to_int on the given index" do
@@ -399,19 +394,19 @@ describe :string_slice_regexp_index, shared: true do
   end
 
   it "raises a TypeError when the given index can't be converted to Integer" do
-    -> { "hello".send(@method, /(.)(.)(.)/, mock('x')) }.should raise_error(TypeError)
-    -> { "hello".send(@method, /(.)(.)(.)/, {})        }.should raise_error(TypeError)
-    -> { "hello".send(@method, /(.)(.)(.)/, [])        }.should raise_error(TypeError)
+    -> { "hello".send(@method, /(.)(.)(.)/, mock('x')) }.should.raise(TypeError)
+    -> { "hello".send(@method, /(.)(.)(.)/, {})        }.should.raise(TypeError)
+    -> { "hello".send(@method, /(.)(.)(.)/, [])        }.should.raise(TypeError)
   end
 
   it "raises a TypeError when the given index is nil" do
-    -> { "hello".send(@method, /(.)(.)(.)/, nil) }.should raise_error(TypeError)
+    -> { "hello".send(@method, /(.)(.)(.)/, nil) }.should.raise(TypeError)
   end
 
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.send(@method, /(.)(.)/, 0).should be_an_instance_of(StringSpecs::MyString)
-    s.send(@method, /(.)(.)/, 1).should be_an_instance_of(StringSpecs::MyString)
+    s.send(@method, /(.)(.)/, 0).should.instance_of?(String)
+    s.send(@method, /(.)(.)/, 1).should.instance_of?(String)
   end
 
   it "sets $~ to MatchData when there is a match and nil when there's none" do
@@ -432,19 +427,6 @@ describe :string_slice_string, shared: true do
     "hello there".send(@method, s).should == s
   end
 
-  it "taints resulting strings when other is tainted" do
-    strs = ["", "hello world", "hello"]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      strs.each do |other|
-        r = str.send(@method, other)
-
-        r.tainted?.should == !r.nil? & other.tainted?
-      end
-    end
-  end
-
   it "doesn't set $~" do
     $~ = nil
 
@@ -460,14 +442,14 @@ describe :string_slice_string, shared: true do
     o = mock('x')
     o.should_not_receive(:to_str)
 
-    -> { "hello".send(@method, o) }.should raise_error(TypeError)
+    -> { "hello".send(@method, o) }.should.raise(TypeError)
   end
 
-  it "returns a subclass instance when given a subclass instance" do
+  it "returns a String instance when given a subclass instance" do
     s = StringSpecs::MyString.new("el")
     r = "hello".send(@method, s)
     r.should == "el"
-    r.should be_an_instance_of(StringSpecs::MyString)
+    r.should.instance_of?(String)
   end
 end
 
@@ -493,51 +475,29 @@ describe :string_slice_regexp_group, shared: true do
       "hello there".send(@method, /(?<g>h(?<g>.))/, 'g').should == "e"
     end
 
-    it "always taints resulting strings when self or regexp is tainted" do
-      strs = ["hello world"]
-      strs += strs.map { |s| s.dup.taint }
-
-      strs.each do |str|
-        str.send(@method, /(?<hi>hello)/, 'hi').tainted?.should == str.tainted?
-
-        str.send(@method, /(?<g>(.)(.)(.))/, 'g').tainted?.should == str.tainted?
-        str.send(@method, /(?<h>.)(.)(.)/, 'h').tainted?.should == str.tainted?
-        str.send(@method, /(.)(?<a>.)(.)/, 'a').tainted?.should == str.tainted?
-        str.send(@method, /(.)(.)(?<r>.)/, 'r').tainted?.should == str.tainted?
-        str.send(@method, /(?<h>.)(?<a>.)(?<r>.)/, 'r').tainted?.should == str.tainted?
-
-        tainted_re = /(?<a>.)(?<b>.)(?<c>.)/
-        tainted_re.taint
-
-        str.send(@method, tainted_re, 'a').tainted?.should be_true
-        str.send(@method, tainted_re, 'b').tainted?.should be_true
-        str.send(@method, tainted_re, 'c').tainted?.should be_true
-      end
-    end
-
     it "returns nil if there is no match" do
-      "hello there".send(@method, /(?<whut>what?)/, 'whut').should be_nil
+      "hello there".send(@method, /(?<whut>what?)/, 'whut').should == nil
     end
 
     it "raises an IndexError if there is no capture for the given name" do
       -> do
         "hello there".send(@method, /[aeiou](.)\1/, 'non')
-      end.should raise_error(IndexError)
+      end.should.raise(IndexError)
     end
 
     it "raises a TypeError when the given name is not a String" do
-      -> { "hello".send(@method, /(?<q>.)/, mock('x')) }.should raise_error(TypeError)
-      -> { "hello".send(@method, /(?<q>.)/, {})        }.should raise_error(TypeError)
-      -> { "hello".send(@method, /(?<q>.)/, [])        }.should raise_error(TypeError)
+      -> { "hello".send(@method, /(?<q>.)/, mock('x')) }.should.raise(TypeError)
+      -> { "hello".send(@method, /(?<q>.)/, {})        }.should.raise(TypeError)
+      -> { "hello".send(@method, /(?<q>.)/, [])        }.should.raise(TypeError)
     end
 
     it "raises an IndexError when given the empty String as a group name" do
-      -> { "hello".send(@method, /(?<q>)/, '') }.should raise_error(IndexError)
+      -> { "hello".send(@method, /(?<q>)/, '') }.should.raise(IndexError)
     end
 
-    it "returns subclass instances" do
+    it "returns String instances" do
       s = StringSpecs::MyString.new("hello")
-      s.send(@method, /(?<q>.)/, 'q').should be_an_instance_of(StringSpecs::MyString)
+      s.send(@method, /(?<q>.)/, 'q').should.instance_of?(String)
     end
 
     it "sets $~ to MatchData when there is a match and nil when there's none" do
@@ -545,13 +505,13 @@ describe :string_slice_regexp_group, shared: true do
       $~[0].should == 'he'
 
       'hello'.send(@method, /(?<non>not)/, 'non')
-      $~.should be_nil
+      $~.should == nil
     end
   end
 end
 
 describe :string_slice_symbol, shared: true do
   it "raises TypeError" do
-    -> { 'hello'.send(@method, :hello) }.should raise_error(TypeError)
+    -> { 'hello'.send(@method, :hello) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/string/shared/strip.rb b/spec/ruby/core/string/shared/strip.rb
new file mode 100644
index 0000000000..39c7232ff9
--- /dev/null
+++ b/spec/ruby/core/string/shared/strip.rb
@@ -0,0 +1,14 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe :string_strip, shared: true do
+  it "returns a String in the same encoding as self" do
+    " hello ".encode("US-ASCII").send(@method).encoding.should == Encoding::US_ASCII
+  end
+
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new(" hello ").send(@method).should.instance_of?(String)
+    StringSpecs::MyString.new(" ").send(@method).should.instance_of?(String)
+    StringSpecs::MyString.new("").send(@method).should.instance_of?(String)
+  end
+end
diff --git a/spec/ruby/core/string/shared/succ.rb b/spec/ruby/core/string/shared/succ.rb
index 31b4a8b5dd..8f1d327741 100644
--- a/spec/ruby/core/string/shared/succ.rb
+++ b/spec/ruby/core/string/shared/succ.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 describe :string_succ, shared: true do
   it "returns an empty string for empty strings" do
     "".send(@method).should == ""
@@ -59,30 +59,29 @@ describe :string_succ, shared: true do
     "\xFF\xFF".send(@method).should == "\x01\x00\x00"
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("").send(@method).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("a").send(@method).should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("z").send(@method).should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("").send(@method).should.instance_of?(String)
+    StringSpecs::MyString.new("a").send(@method).should.instance_of?(String)
+    StringSpecs::MyString.new("z").send(@method).should.instance_of?(String)
   end
 
-  it "taints the result if self is tainted" do
-    ["", "a", "z", "Z", "9", "\xFF", "\xFF\xFF"].each do |s|
-      s.taint.send(@method).tainted?.should == true
-    end
+  it "returns a String in the same encoding as self" do
+    "z".encode("US-ASCII").send(@method).encoding.should == Encoding::US_ASCII
   end
 end
 
 describe :string_succ_bang, shared: true do
   it "is equivalent to succ, but modifies self in place (still returns self)" do
     ["", "abcd", "THX1138"].each do |s|
+      s = +s
       r = s.dup.send(@method)
-      s.send(@method).should equal(s)
+      s.send(@method).should.equal?(s)
       s.should == r
     end
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { "".freeze.send(@method)     }.should raise_error(frozen_error_class)
-    -> { "abcd".freeze.send(@method) }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { "".freeze.send(@method)     }.should.raise(FrozenError)
+    -> { "abcd".freeze.send(@method) }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/shared/to_a.rb b/spec/ruby/core/string/shared/to_a.rb
deleted file mode 100644
index bad3ea6584..0000000000
--- a/spec/ruby/core/string/shared/to_a.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-describe :string_to_a, shared: true do
-  it "returns an empty array for empty strings" do
-    "".send(@method).should == []
-  end
-
-  it "returns an array containing the string for non-empty strings" do
-    "hello".send(@method).should == ["hello"]
-  end
-end
diff --git a/spec/ruby/core/string/shared/to_s.rb b/spec/ruby/core/string/shared/to_s.rb
index a5a13e4f26..96c59470d6 100644
--- a/spec/ruby/core/string/shared/to_s.rb
+++ b/spec/ruby/core/string/shared/to_s.rb
@@ -1,18 +1,13 @@
 describe :string_to_s, shared: true do
   it "returns self when self.class == String" do
     a = "a string"
-    a.should equal(a.send(@method))
+    a.should.equal?(a.send(@method))
   end
 
   it "returns a new instance of String when called on a subclass" do
     a = StringSpecs::MyString.new("a string")
     s = a.send(@method)
     s.should == "a string"
-    s.should be_an_instance_of(String)
-  end
-
-  it "taints the result when self is tainted" do
-    "x".taint.send(@method).tainted?.should == true
-    StringSpecs::MyString.new("x").taint.send(@method).tainted?.should == true
+    s.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/core/string/shared/to_sym.rb b/spec/ruby/core/string/shared/to_sym.rb
index 1180d64712..2a8a2e3182 100644
--- a/spec/ruby/core/string/shared/to_sym.rb
+++ b/spec/ruby/core/string/shared/to_sym.rb
@@ -1,42 +1,42 @@
 describe :string_to_sym, shared: true do
   it "returns the symbol corresponding to self" do
-    "Koala".send(@method).should equal :Koala
-    'cat'.send(@method).should equal :cat
-    '@cat'.send(@method).should equal :@cat
-    'cat and dog'.send(@method).should equal :"cat and dog"
-    "abc=".send(@method).should equal :abc=
+    "Koala".send(@method).should.equal? :Koala
+    'cat'.send(@method).should.equal? :cat
+    '@cat'.send(@method).should.equal? :@cat
+    'cat and dog'.send(@method).should.equal? :"cat and dog"
+    "abc=".send(@method).should.equal? :abc=
   end
 
   it "does not special case +(binary) and -(binary)" do
-    "+(binary)".send(@method).should equal :"+(binary)"
-    "-(binary)".send(@method).should equal :"-(binary)"
+    "+(binary)".send(@method).should.equal? :"+(binary)"
+    "-(binary)".send(@method).should.equal? :"-(binary)"
   end
 
   it "does not special case certain operators" do
-    "!@".send(@method).should equal :"!@"
-    "~@".send(@method).should equal :"~@"
-    "!(unary)".send(@method).should equal :"!(unary)"
-    "~(unary)".send(@method).should equal :"~(unary)"
-    "+(unary)".send(@method).should equal :"+(unary)"
-    "-(unary)".send(@method).should equal :"-(unary)"
+    "!@".send(@method).should.equal? :"!@"
+    "~@".send(@method).should.equal? :"~@"
+    "!(unary)".send(@method).should.equal? :"!(unary)"
+    "~(unary)".send(@method).should.equal? :"~(unary)"
+    "+(unary)".send(@method).should.equal? :"+(unary)"
+    "-(unary)".send(@method).should.equal? :"-(unary)"
   end
 
   it "returns a US-ASCII Symbol for a UTF-8 String containing only US-ASCII characters" do
     sym = "foobar".send(@method)
     sym.encoding.should == Encoding::US_ASCII
-    sym.should equal :"foobar"
+    sym.should.equal? :"foobar"
   end
 
   it "returns a US-ASCII Symbol for a binary String containing only US-ASCII characters" do
     sym = "foobar".b.send(@method)
     sym.encoding.should == Encoding::US_ASCII
-    sym.should equal :"foobar"
+    sym.should.equal? :"foobar"
   end
 
   it "returns a UTF-8 Symbol for a UTF-8 String containing non US-ASCII characters" do
     sym = "il était une fois".send(@method)
     sym.encoding.should == Encoding::UTF_8
-    sym.should equal :"il était une #{'fois'}"
+    sym.should.equal? :"il était une #{'fois'}"
   end
 
   it "returns a UTF-16LE Symbol for a UTF-16LE String containing non US-ASCII characters" do
@@ -53,11 +53,20 @@ describe :string_to_sym, shared: true do
     sym.to_s.should == binary_string
   end
 
+  it "ignores existing symbols with different encoding" do
+    source = "fée"
+
+    iso_symbol = source.dup.force_encoding(Encoding::ISO_8859_1).send(@method)
+    iso_symbol.encoding.should == Encoding::ISO_8859_1
+    binary_symbol = source.dup.force_encoding(Encoding::BINARY).send(@method)
+    binary_symbol.encoding.should == Encoding::BINARY
+  end
+
   it "raises an EncodingError for UTF-8 String containing invalid bytes" do
     invalid_utf8 = "\xC3"
-    invalid_utf8.valid_encoding?.should == false
+    invalid_utf8.should_not.valid_encoding?
     -> {
       invalid_utf8.send(@method)
-    }.should raise_error(EncodingError, /invalid/)
+    }.should.raise(EncodingError, 'invalid symbol in encoding UTF-8 :"\xC3"')
   end
 end
diff --git a/spec/ruby/core/string/slice_spec.rb b/spec/ruby/core/string/slice_spec.rb
index 2af663117c..14e2251b3f 100644
--- a/spec/ruby/core/string/slice_spec.rb
+++ b/spec/ruby/core/string/slice_spec.rb
@@ -1,5 +1,5 @@
 # -*- encoding: utf-8 -*-
-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/slice'
@@ -53,10 +53,10 @@ describe "String#slice! with index" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { "hello".freeze.slice!(1)  }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(10) }.should raise_error(frozen_error_class)
-    -> { "".freeze.slice!(0)       }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { "hello".freeze.slice!(1)  }.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(10) }.should.raise(FrozenError)
+    -> { "".freeze.slice!(0)       }.should.raise(FrozenError)
   end
 
   it "calls to_int on index" do
@@ -94,14 +94,6 @@ describe "String#slice! with index, length" do
     a.should == "h"
   end
 
-  it "always taints resulting strings when self is tainted" do
-    str = "hello world"
-    str.taint
-
-    str.slice!(0, 0).tainted?.should == true
-    str.slice!(2, 1).tainted?.should == true
-  end
-
   it "returns nil if the given position is out of self" do
     a = "hello"
     a.slice(10, 3).should == nil
@@ -117,14 +109,14 @@ describe "String#slice! with index, length" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { "hello".freeze.slice!(1, 2)  }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(10, 3) }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(-10, 3)}.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(4, -3) }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(10, 3) }.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(-10, 3)}.should raise_error(frozen_error_class)
-    -> { "hello".freeze.slice!(4, -3) }.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { "hello".freeze.slice!(1, 2)  }.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(10, 3) }.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(-10, 3)}.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(4, -3) }.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(10, 3) }.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(-10, 3)}.should.raise(FrozenError)
+    -> { "hello".freeze.slice!(4, -3) }.should.raise(FrozenError)
   end
 
   it "calls to_int on idx and length" do
@@ -140,13 +132,12 @@ describe "String#slice! with index, length" do
     "hello".slice!(obj, obj).should == "ll"
   end
 
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.slice!(0, 0).should be_an_instance_of(StringSpecs::MyString)
-    s.slice!(0, 4).should be_an_instance_of(StringSpecs::MyString)
+    s.slice!(0, 0).should.instance_of?(String)
+    s.slice!(0, 4).should.instance_of?(String)
   end
 
-
   it "returns the substring given by the character offsets" do
     "hellö there".slice!(1,0).should == ""
     "hellö there".slice!(1,3).should == "ell"
@@ -184,18 +175,10 @@ describe "String#slice! Range" do
     b.should == "hello"
   end
 
-  it "always taints resulting strings when self is tainted" do
-    str = "hello world"
-    str.taint
-
-    str.slice!(0..0).tainted?.should == true
-    str.slice!(2..3).tainted?.should == true
-  end
-
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.slice!(0...0).should be_an_instance_of(StringSpecs::MyString)
-    s.slice!(0..4).should be_an_instance_of(StringSpecs::MyString)
+    s.slice!(0...0).should.instance_of?(String)
+    s.slice!(0..4).should.instance_of?(String)
   end
 
   it "calls to_int on range arguments" do
@@ -244,13 +227,13 @@ describe "String#slice! Range" do
   end
 
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "hello".freeze.slice!(1..3)  }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "hello".freeze.slice!(1..3)  }.should.raise(FrozenError)
   end
 
   # see redmine #1551
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> { "hello".freeze.slice!(10..20)}.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> { "hello".freeze.slice!(10..20)}.should.raise(FrozenError)
   end
 end
 
@@ -271,32 +254,10 @@ describe "String#slice! with Regexp" do
     s.should == "this is a string"
   end
 
-  it "always taints resulting strings when self or regexp is tainted" do
-    strs = ["hello world"]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      str = str.dup
-      str.slice!(//).tainted?.should == str.tainted?
-      str.slice!(/hello/).tainted?.should == str.tainted?
-
-      tainted_re = /./
-      tainted_re.taint
-
-      str.slice!(tainted_re).tainted?.should == true
-    end
-  end
-
-  it "doesn't taint self when regexp is tainted" do
-    s = "hello"
-    s.slice!(/./.taint)
-    s.tainted?.should == false
-  end
-
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.slice!(//).should be_an_instance_of(StringSpecs::MyString)
-    s.slice!(/../).should be_an_instance_of(StringSpecs::MyString)
+    s.slice!(//).should.instance_of?(String)
+    s.slice!(/../).should.instance_of?(String)
   end
 
   it "returns the matching portion of self with a multi byte character" do
@@ -312,12 +273,12 @@ describe "String#slice! with Regexp" do
     $~.should == nil
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "this is a string".freeze.slice!(/s.*t/) }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "this is a string".freeze.slice!(/s.*t/) }.should.raise(FrozenError)
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> { "this is a string".freeze.slice!(/zzz/)  }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> { "this is a string".freeze.slice!(/zzz/)  }.should.raise(FrozenError)
   end
 end
 
@@ -330,28 +291,6 @@ describe "String#slice! with Regexp, index" do
     str.should == "ho here"
   end
 
-  it "always taints resulting strings when self or regexp is tainted" do
-    strs = ["hello world"]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      str = str.dup
-      str.slice!(//, 0).tainted?.should == str.tainted?
-      str.slice!(/hello/, 0).tainted?.should == str.tainted?
-
-      tainted_re = /(.)(.)(.)/
-      tainted_re.taint
-
-      str.slice!(tainted_re, 1).tainted?.should == true
-    end
-  end
-
-  it "doesn't taint self when regexp is tainted" do
-    s = "hello"
-    s.slice!(/(.)(.)/.taint, 1)
-    s.tainted?.should == false
-  end
-
   it "returns nil if there was no match" do
     s = "this is a string"
     s.slice!(/x(zzz)/, 1).should == nil
@@ -375,10 +314,10 @@ describe "String#slice! with Regexp, index" do
     "har".slice!(/(.)(.)(.)/, obj).should == "a"
   end
 
-  it "returns subclass instances" do
+  it "returns String instances" do
     s = StringSpecs::MyString.new("hello")
-    s.slice!(/(.)(.)/, 0).should be_an_instance_of(StringSpecs::MyString)
-    s.slice!(/(.)(.)/, 1).should be_an_instance_of(StringSpecs::MyString)
+    s.slice!(/(.)(.)/, 0).should.instance_of?(String)
+    s.slice!(/(.)(.)/, 1).should.instance_of?(String)
   end
 
   it "returns the encoding aware capture for the given index" do
@@ -402,10 +341,10 @@ describe "String#slice! with Regexp, index" do
     $~.should == nil
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { "this is a string".freeze.slice!(/s.*t/)  }.should raise_error(frozen_error_class)
-    -> { "this is a string".freeze.slice!(/zzz/, 0)}.should raise_error(frozen_error_class)
-    -> { "this is a string".freeze.slice!(/(.)/, 2)}.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { "this is a string".freeze.slice!(/s.*t/)  }.should.raise(FrozenError)
+    -> { "this is a string".freeze.slice!(/zzz/, 0)}.should.raise(FrozenError)
+    -> { "this is a string".freeze.slice!(/(.)/, 2)}.should.raise(FrozenError)
   end
 end
 
@@ -416,21 +355,6 @@ describe "String#slice! with String" do
     c.should == "he hello"
   end
 
-  it "taints resulting strings when other is tainted" do
-    strs = ["", "hello world", "hello"]
-    strs += strs.map { |s| s.dup.taint }
-
-    strs.each do |str|
-      str = str.dup
-      strs.each do |other|
-        other = other.dup
-        r = str.slice!(other)
-
-        r.tainted?.should == !r.nil? & other.tainted?
-      end
-    end
-  end
-
   it "doesn't set $~" do
     $~ = nil
 
@@ -448,19 +372,19 @@ describe "String#slice! with String" do
     o = mock('x')
     o.should_not_receive(:to_str)
 
-    -> { "hello".slice!(o) }.should raise_error(TypeError)
+    -> { "hello".slice!(o) }.should.raise(TypeError)
   end
 
   it "returns a subclass instance when given a subclass instance" do
     s = StringSpecs::MyString.new("el")
     r = "hello".slice!(s)
     r.should == "el"
-    r.should be_an_instance_of(StringSpecs::MyString)
+    r.should.instance_of?(String)
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
-    -> { "hello hello".freeze.slice!('llo')     }.should raise_error(frozen_error_class)
-    -> { "this is a string".freeze.slice!('zzz')}.should raise_error(frozen_error_class)
-    -> { "this is a string".freeze.slice!('zzz')}.should raise_error(frozen_error_class)
+  it "raises a FrozenError if self is frozen" do
+    -> { "hello hello".freeze.slice!('llo')     }.should.raise(FrozenError)
+    -> { "this is a string".freeze.slice!('zzz')}.should.raise(FrozenError)
+    -> { "this is a string".freeze.slice!('zzz')}.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/split_spec.rb b/spec/ruby/core/string/split_spec.rb
index 655f0dae76..6e8c1c6219 100644
--- a/spec/ruby/core/string/split_spec.rb
+++ b/spec/ruby/core/string/split_spec.rb
@@ -3,13 +3,18 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "String#split with String" do
+  it "throws an ArgumentError if the string  is not a valid" do
+    s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+
+    -> { s.split }.should.raise(ArgumentError)
+    -> { s.split(':') }.should.raise(ArgumentError)
+  end
+
   it "throws an ArgumentError if the pattern is not a valid string" do
     str = 'проверка'
-    broken_str = 'проверка'
-    broken_str.force_encoding('binary')
-    broken_str.chop!
-    broken_str.force_encoding('utf-8')
-    -> { str.split(broken_str) }.should raise_error(ArgumentError)
+    broken_str = "\xDF".dup.force_encoding(Encoding::UTF_8)
+
+    -> { str.split(broken_str) }.should.raise(ArgumentError)
   end
 
   it "splits on multibyte characters" do
@@ -24,9 +29,35 @@ describe "String#split with String" do
     "1,2,,3,4,,".split(',').should == ["1", "2", "", "3", "4"]
     "1,2,,3,4,,".split(',', 0).should == ["1", "2", "", "3", "4"]
     "  a  b  c\nd  ".split("  ").should == ["", "a", "b", "c\nd"]
+    "  a  あ  c\nd  ".split("  ").should == ["", "a", "あ", "c\nd"]
     "hai".split("hai").should == []
     ",".split(",").should == []
     ",".split(",", 0).should == []
+    "あ".split("あ").should == []
+    "あ".split("あ", 0).should == []
+  end
+
+  it "does not suppress trailing empty fields when a positive limit is given" do
+    " 1 2 ".split(" ", 2).should == ["1", "2 "]
+    " 1 2 ".split(" ", 3).should == ["1", "2", ""]
+    " 1 2 ".split(" ", 4).should == ["1", "2", ""]
+    " 1 あ ".split(" ", 2).should == ["1", "あ "]
+    " 1 あ ".split(" ", 3).should == ["1", "あ", ""]
+    " 1 あ ".split(" ", 4).should == ["1", "あ", ""]
+
+    "1,2,".split(',', 2).should == ["1", "2,"]
+    "1,2,".split(',', 3).should == ["1", "2", ""]
+    "1,2,".split(',', 4).should == ["1", "2", ""]
+    "1,あ,".split(',', 2).should == ["1", "あ,"]
+    "1,あ,".split(',', 3).should == ["1", "あ", ""]
+    "1,あ,".split(',', 4).should == ["1", "あ", ""]
+
+    "1 2 ".split(/ /, 2).should == ["1", "2 "]
+    "1 2 ".split(/ /, 3).should == ["1", "2", ""]
+    "1 2 ".split(/ /, 4).should == ["1", "2", ""]
+    "1 あ ".split(/ /, 2).should == ["1", "あ "]
+    "1 あ ".split(/ /, 3).should == ["1", "あ", ""]
+    "1 あ ".split(/ /, 4).should == ["1", "あ", ""]
   end
 
   it "returns an array with one entry if limit is 1: the original string" do
@@ -62,6 +93,10 @@ describe "String#split with String" do
     ",".split(",", -1).should == ["", ""]
   end
 
+  it "raises a RangeError when the limit is larger than int" do
+    -> { "a,b".split(" ", 2147483649) }.should.raise(RangeError)
+  end
+
   it "defaults to $; when string isn't given or nil" do
     suppress_warning do
       old_fs = $;
@@ -86,6 +121,22 @@ describe "String#split with String" do
     end
   end
 
+  context "when $; is not nil" do
+    before do
+      suppress_warning do
+        @old_value, $; = $;, 'foobar'
+      end
+    end
+
+    after do
+      $; = @old_value
+    end
+
+    it "warns" do
+      -> { "".split }.should complain(/warning: \$; is set to non-nil value/)
+    end
+  end
+
   it "ignores leading and continuous whitespace when string is a single space" do
     " now's  the time  ".split(' ').should == ["now's", "the", "time"]
     " now's  the time  ".split(' ', -1).should == ["now's", "the", "time", ""]
@@ -141,48 +192,48 @@ describe "String#split with String" do
     "foo".split("bar", 3).should == ["foo"]
   end
 
-  it "returns subclass instances based on self" do
+  it "returns String instances based on self" do
     ["", "x.y.z.", "  x  y  "].each do |str|
       ["", ".", " "].each do |pat|
         [-1, 0, 1, 2].each do |limit|
           StringSpecs::MyString.new(str).split(pat, limit).each do |x|
-            x.should be_an_instance_of(StringSpecs::MyString)
+            x.should.instance_of?(String)
           end
 
           str.split(StringSpecs::MyString.new(pat), limit).each do |x|
-            x.should be_an_instance_of(String)
+            x.should.instance_of?(String)
           end
         end
       end
     end
   end
 
-  it "does not call constructor on created subclass instances" do
-    # can't call should_not_receive on an object that doesn't yet exist
-    # so failure here is signalled by exception, not expectation failure
+  it "returns an empty array when whitespace is split on whitespace" do
+    " ".split(" ").should == []
+    " \n ".split(" ").should == []
+    "  ".split(" ").should == []
+    " \t ".split(" ").should == []
+  end
 
-    s = StringSpecs::StringWithRaisingConstructor.new('silly:string')
-    s.split(':').first.should == 'silly'
+  it "doesn't split on non-ascii whitespace" do
+    "a\u{2008}b".split(" ").should == ["a\u{2008}b"]
   end
 
-  it "taints the resulting strings if self is tainted" do
-    ["", "x.y.z.", "  x  y  "].each do |str|
-      ["", ".", " "].each do |pat|
-        [-1, 0, 1, 2].each do |limit|
-          str.dup.taint.split(pat).each do |x|
-            x.tainted?.should == true
-          end
+  it "returns Strings in the same encoding as self" do
+    strings = "hello world".encode("US-ASCII").split(" ")
 
-          str.split(pat.dup.taint).each do |x|
-            x.tainted?.should == false
-          end
-        end
-      end
-    end
+    strings[0].encoding.should == Encoding::US_ASCII
+    strings[1].encoding.should == Encoding::US_ASCII
   end
 end
 
 describe "String#split with Regexp" do
+  it "throws an ArgumentError if the string  is not a valid" do
+    s = "\xDF".dup.force_encoding(Encoding::UTF_8)
+
+    -> { s.split(/./) }.should.raise(ArgumentError)
+  end
+
   it "divides self on regexp matches" do
     " now's  the time".split(/ /).should == ["", "now's", "", "the", "time"]
     " x\ny ".split(/ /).should == ["", "x\ny"]
@@ -316,8 +367,8 @@ describe "String#split with Regexp" do
   end
 
   it "returns a type error if limit can't be converted to an integer" do
-    -> {"1.2.3.4".split(".", "three")}.should raise_error(TypeError)
-    -> {"1.2.3.4".split(".", nil)    }.should raise_error(TypeError)
+    -> {"1.2.3.4".split(".", "three")}.should.raise(TypeError)
+    -> {"1.2.3.4".split(".", nil)    }.should.raise(TypeError)
   end
 
   it "doesn't set $~" do
@@ -335,95 +386,161 @@ describe "String#split with Regexp" do
     "foo".split(/bar/, 3).should == ["foo"]
   end
 
-  it "returns subclass instances based on self" do
+  it "returns String instances based on self" do
     ["", "x:y:z:", "  x  y  "].each do |str|
       [//, /:/, /\s+/].each do |pat|
         [-1, 0, 1, 2].each do |limit|
           StringSpecs::MyString.new(str).split(pat, limit).each do |x|
-            x.should be_an_instance_of(StringSpecs::MyString)
-          end
-        end
-      end
-    end
-  end
-
-  it "does not call constructor on created subclass instances" do
-    # can't call should_not_receive on an object that doesn't yet exist
-    # so failure here is signalled by exception, not expectation failure
-
-    s = StringSpecs::StringWithRaisingConstructor.new('silly:string')
-    s.split(/:/).first.should == 'silly'
-  end
-
-  it "taints the resulting strings if self is tainted" do
-    ["", "x:y:z:", "  x  y  "].each do |str|
-      [//, /:/, /\s+/].each do |pat|
-        [-1, 0, 1, 2].each do |limit|
-          str.dup.taint.split(pat, limit).each do |x|
-            # See the spec below for why the conditional is here
-            x.tainted?.should be_true unless x.empty?
-          end
-        end
-      end
-    end
-  end
-
-  it "taints an empty string if self is tainted" do
-    ":".taint.split(//, -1).last.tainted?.should be_true
-  end
-
-  it "doesn't taints the resulting strings if the Regexp is tainted" do
-    ["", "x:y:z:", "  x  y  "].each do |str|
-      [//, /:/, /\s+/].each do |pat|
-        [-1, 0, 1, 2].each do |limit|
-          str.split(pat.dup.taint, limit).each do |x|
-            x.tainted?.should be_false
+            x.should.instance_of?(String)
           end
         end
       end
     end
   end
 
-  it "retains the encoding of the source string" do
+  it "returns Strings in the same encoding as self" do
     ary = "а б в".split
     encodings = ary.map { |s| s.encoding }
     encodings.should == [Encoding::UTF_8, Encoding::UTF_8, Encoding::UTF_8]
   end
 
-
   it "splits a string on each character for a multibyte encoding and empty split" do
     "That's why eﬃciency could not be helped".split("").size.should == 39
   end
 
   it "returns an ArgumentError if an invalid UTF-8 string is supplied" do
-    broken_str = 'проверка' # in russian, means "test"
+    broken_str = +'проверка' # in russian, means "test"
     broken_str.force_encoding('binary')
     broken_str.chop!
     broken_str.force_encoding('utf-8')
-    ->{ broken_str.split(/\r\n|\r|\n/) }.should raise_error(ArgumentError)
+    ->{ broken_str.split(/\r\n|\r|\n/) }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    it "yields each split substrings if a block is given" do
+  # See https://bugs.ruby-lang.org/issues/12689 and https://github.com/jruby/jruby/issues/4868
+  it "allows concurrent Regexp calls in a shared context" do
+    str = 'a,b,c,d,e'
+
+    p = proc { str.split(/,/) }
+    results = 10.times.map { Thread.new { x = nil; 100.times { x = p.call }; x } }.map(&:value)
+
+    results.should == [%w[a b c d e]] * 10
+  end
+
+  context "when a block is given" do
+    it "yields each split substring with default pattern" do
       a = []
-      returned_object = "chunky bacon".split(" ") { |str| a << str.capitalize }
+      returned_object = "chunky bacon".split { |str| a << str.capitalize }
 
       returned_object.should == "chunky bacon"
       a.should == ["Chunky", "Bacon"]
     end
 
-    describe "for a String subclass" do
-      it "yields instances of the same subclass" do
-        a = []
-        StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
-        first, last = a
+    it "yields each split substring with default pattern for a lazy substring" do
+      a = []
+      returned_object = "chunky bacon"[1...-1].split { |str| a << str.capitalize }
+
+      returned_object.should == "hunky baco"
+      a.should == ["Hunky", "Baco"]
+    end
+
+    it "yields each split substring with default pattern for a non-ASCII string" do
+      a = []
+      returned_object = "l'été arrive bientôt".split { |str| a << str }
 
-        first.should be_an_instance_of(StringSpecs::MyString)
-        first.should == "a"
+      returned_object.should == "l'été arrive bientôt"
+      a.should == ["l'été", "arrive", "bientôt"]
+    end
 
-        last.should be_an_instance_of(StringSpecs::MyString)
-        last.should == "b"
-      end
+    it "yields each split substring with default pattern for a non-ASCII lazy substring" do
+      a = []
+      returned_object = "l'été arrive bientôt"[1...-1].split { |str| a << str }
+
+      returned_object.should == "'été arrive bientô"
+      a.should == ["'été", "arrive", "bientô"]
+    end
+
+    it "yields the string when limit is 1" do
+      a = []
+      returned_object = "chunky bacon".split("", 1) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky bacon"
+      a.should == ["Chunky bacon"]
+    end
+
+    it "yields each split letter" do
+      a = []
+      returned_object = "chunky".split("", 0) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky"
+      a.should == %w(C H U N K Y)
+    end
+
+    it "yields each split substring with a pattern" do
+      a = []
+      returned_object = "chunky-bacon".split("-", 0) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky-bacon"
+      a.should == ["Chunky", "Bacon"]
     end
+
+    it "yields each split substring with empty regexp pattern" do
+      a = []
+      returned_object = "chunky".split(//) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky"
+      a.should == %w(C H U N K Y)
+    end
+
+    it "yields each split substring with empty regexp pattern and limit" do
+      a = []
+      returned_object = "chunky".split(//, 3) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky"
+      a.should == %w(C H Unky)
+    end
+
+    it "yields each split substring with a regexp pattern" do
+      a = []
+      returned_object = "chunky:bacon".split(/:/) { |str| a << str.capitalize }
+
+      returned_object.should == "chunky:bacon"
+      a.should == ["Chunky", "Bacon"]
+    end
+
+    it "returns a string as is (and doesn't call block) if it is empty" do
+      a = []
+      returned_object = "".split { |str| a << str.capitalize }
+
+      returned_object.should == ""
+      a.should == []
+    end
+  end
+
+  describe "for a String subclass" do
+    it "yields instances of String" do
+      a = []
+      StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
+      first, last = a
+
+      first.should.instance_of?(String)
+      first.should == "a"
+
+      last.should.instance_of?(String)
+      last.should == "b"
+    end
+  end
+
+  it "raises a TypeError when not called with nil, String, or Regexp" do
+    -> { "hello".split(42) }.should.raise(TypeError)
+    -> { "hello".split(:ll) }.should.raise(TypeError)
+    -> { "hello".split(false) }.should.raise(TypeError)
+    -> { "hello".split(Object.new) }.should.raise(TypeError)
+  end
+
+  it "returns Strings in the same encoding as self" do
+    strings = "hello world".encode("US-ASCII").split(/ /)
+
+    strings[0].encoding.should == Encoding::US_ASCII
+    strings[1].encoding.should == Encoding::US_ASCII
   end
 end
diff --git a/spec/ruby/core/string/squeeze_spec.rb b/spec/ruby/core/string/squeeze_spec.rb
index bcc320bb5b..52b6e1eed4 100644
--- a/spec/ruby/core/string/squeeze_spec.rb
+++ b/spec/ruby/core/string/squeeze_spec.rb
@@ -1,4 +1,5 @@
-# -*- encoding: binary -*-
+# encoding: binary
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -50,16 +51,8 @@ describe "String#squeeze" do
 
   it "raises an ArgumentError when the parameter is out of sequence" do
     s = "--subbookkeeper--"
-    -> { s.squeeze("e-b") }.should raise_error(ArgumentError)
-    -> { s.squeeze("^e-b") }.should raise_error(ArgumentError)
-  end
-
-  it "taints the result when self is tainted" do
-    "hello".taint.squeeze("e").tainted?.should == true
-    "hello".taint.squeeze("a-z").tainted?.should == true
-
-    "hello".squeeze("e".taint).tainted?.should == false
-    "hello".squeeze("l".taint).tainted?.should == false
+    -> { s.squeeze("e-b") }.should.raise(ArgumentError)
+    -> { s.squeeze("^e-b") }.should.raise(ArgumentError)
   end
 
   it "tries to convert each set arg to a string using to_str" do
@@ -72,21 +65,26 @@ describe "String#squeeze" do
     "hello room".squeeze(other_string, other_string2).should == "hello rom"
   end
 
+  it "returns a String in the same encoding as self" do
+    "yellow moon".encode("US-ASCII").squeeze.encoding.should == Encoding::US_ASCII
+    "yellow moon".encode("US-ASCII").squeeze("a").encoding.should == Encoding::US_ASCII
+  end
+
   it "raises a TypeError when one set arg can't be converted to a string" do
-    -> { "hello world".squeeze([])        }.should raise_error(TypeError)
-    -> { "hello world".squeeze(Object.new)}.should raise_error(TypeError)
-    -> { "hello world".squeeze(mock('x')) }.should raise_error(TypeError)
+    -> { "hello world".squeeze([])        }.should.raise(TypeError)
+    -> { "hello world".squeeze(Object.new)}.should.raise(TypeError)
+    -> { "hello world".squeeze(mock('x')) }.should.raise(TypeError)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("oh no!!!").squeeze("!").should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("oh no!!!").squeeze("!").should.instance_of?(String)
   end
 end
 
 describe "String#squeeze!" do
   it "modifies self in place and returns self" do
     a = "yellow moon"
-    a.squeeze!.should equal(a)
+    a.squeeze!.should.equal?(a)
     a.should == "yelow mon"
   end
 
@@ -99,15 +97,15 @@ describe "String#squeeze!" do
 
   it "raises an ArgumentError when the parameter is out of sequence" do
     s = "--subbookkeeper--"
-    -> { s.squeeze!("e-b") }.should raise_error(ArgumentError)
-    -> { s.squeeze!("^e-b") }.should raise_error(ArgumentError)
+    -> { s.squeeze!("e-b") }.should.raise(ArgumentError)
+    -> { s.squeeze!("^e-b") }.should.raise(ArgumentError)
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     a = "yellow moon"
     a.freeze
 
-    -> { a.squeeze!("") }.should raise_error(frozen_error_class)
-    -> { a.squeeze!     }.should raise_error(frozen_error_class)
+    -> { a.squeeze!("") }.should.raise(FrozenError)
+    -> { a.squeeze!     }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/start_with_spec.rb b/spec/ruby/core/string/start_with_spec.rb
index 1000db180c..8b0ba6b5a7 100644
--- a/spec/ruby/core/string/start_with_spec.rb
+++ b/spec/ruby/core/string/start_with_spec.rb
@@ -1,76 +1,18 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../shared/string/start_with'
 
 describe "String#start_with?" do
-  it "returns true only if beginning match" do
-    s = "hello"
-    s.should.start_with?('h')
-    s.should.start_with?('hel')
-    s.should_not.start_with?('el')
-  end
-
-  it "returns true only if any beginning match" do
-    "hello".should.start_with?('x', 'y', 'he', 'z')
-  end
-
-  it "returns true if the search string is empty" do
-    "hello".should.start_with?("")
-    "".should.start_with?("")
-  end
-
-  it "converts its argument using :to_str" do
-    s = "hello"
-    find = mock('h')
-    find.should_receive(:to_str).and_return("h")
-    s.should.start_with?(find)
-  end
+  it_behaves_like :start_with, :to_s
 
-  it "ignores arguments not convertible to string" do
-    "hello".should_not.start_with?()
-    -> { "hello".start_with?(1) }.should raise_error(TypeError)
-    -> { "hello".start_with?(["h"]) }.should raise_error(TypeError)
-    -> { "hello".start_with?(1, nil, "h") }.should raise_error(TypeError)
+  # Here and not in the shared examples because this is invalid as a Symbol
+  it "matches part of a character with the same part" do
+    "\xA9".should.start_with?("\xA9") # A9 is not a character head for UTF-8
   end
 
-  it "uses only the needed arguments" do
-    find = mock('h')
-    find.should_not_receive(:to_str)
-    "hello".should.start_with?("h",find)
-  end
-
-  it "works for multibyte strings" do
-    "céréale".should.start_with?("cér")
-  end
-
-  ruby_version_is "2.5" do
-    it "supports regexps" do
-      regexp = /[h1]/
-      "hello".should.start_with?(regexp)
-      "1337".should.start_with?(regexp)
-      "foxes are 1337".should_not.start_with?(regexp)
-      "chunky\n12bacon".should_not.start_with?(/12/)
-    end
-
-    it "supports regexps with ^ and $ modifiers" do
-      regexp1 = /^\d{2}/
-      regexp2 = /\d{2}$/
-      "12test".should.start_with?(regexp1)
-      "test12".should_not.start_with?(regexp1)
-      "12test".should_not.start_with?(regexp2)
-      "test12".should_not.start_with?(regexp2)
-    end
-
-    it "sets Regexp.last_match if it returns true" do
-      regexp = /test-(\d+)/
-      "test-1337".start_with?(regexp).should be_true
-      Regexp.last_match.should_not be_nil
-      Regexp.last_match[1].should == "1337"
-      $1.should == "1337"
-
-      "test-asdf".start_with?(regexp).should be_false
-      Regexp.last_match.should be_nil
-      $1.should be_nil
-    end
+  it "checks we are matching only part of a character" do
+    "\xe3\x81\x82".size.should == 1
+    "\xe3\x81\x82".should_not.start_with?("\xe3")
   end
 end
diff --git a/spec/ruby/core/string/strip_spec.rb b/spec/ruby/core/string/strip_spec.rb
index c205746483..81994a7f2e 100644
--- a/spec/ruby/core/string/strip_spec.rb
+++ b/spec/ruby/core/string/strip_spec.rb
@@ -1,39 +1,31 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/strip'
 
 describe "String#strip" do
+  it_behaves_like :string_strip, :strip
+
   it "returns a new string with leading and trailing whitespace removed" do
     "   hello   ".strip.should == "hello"
     "   hello world   ".strip.should == "hello world"
     "\tgoodbye\r\v\n".strip.should == "goodbye"
-    "\x00 goodbye \x00".strip.should == "\x00 goodbye"
-  end
-
-  it "returns a copy of self with trailing NULL bytes and whitespace" do
-    " \x00 goodbye \x00 ".strip.should == "\x00 goodbye"
   end
 
-  it "taints the result when self is tainted" do
-    "".taint.strip.tainted?.should == true
-    "ok".taint.strip.tainted?.should == true
-    "  ok  ".taint.strip.tainted?.should == true
+  it "returns a copy of self without leading and trailing NULL bytes and whitespace" do
+    " \x00 goodbye \x00 ".strip.should == "goodbye"
   end
 end
 
 describe "String#strip!" do
   it "modifies self in place and returns self" do
     a = "   hello   "
-    a.strip!.should equal(a)
+    a.strip!.should.equal?(a)
     a.should == "hello"
 
     a = "\tgoodbye\r\v\n"
     a.strip!
     a.should == "goodbye"
-
-    a = "\000 goodbye \000"
-    a.strip!
-    a.should == "\000 goodbye"
-
   end
 
   it "returns nil if no modifications where made" do
@@ -42,19 +34,25 @@ describe "String#strip!" do
     a.should == "hello"
   end
 
-  it "modifies self removing trailing NULL bytes and whitespace" do
-    a = " \x00 goodbye \x00 "
+  it "makes a string empty if it is only whitespace" do
+    "".strip!.should == nil
+    " ".strip.should == ""
+    "  ".strip.should == ""
+  end
+
+  it "removes leading and trailing NULL bytes and whitespace" do
+    a = "\000 goodbye \000"
     a.strip!
-    a.should == "\x00 goodbye"
+    a.should == "goodbye"
   end
 
-  it "raises a #{frozen_error_class} on a frozen instance that is modified" do
-    -> { "  hello  ".freeze.strip! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that is modified" do
+    -> { "  hello  ".freeze.strip! }.should.raise(FrozenError)
   end
 
   # see #1552
-  it "raises a #{frozen_error_class} on a frozen instance that would not be modified" do
-    -> {"hello".freeze.strip! }.should raise_error(frozen_error_class)
-    -> {"".freeze.strip!      }.should raise_error(frozen_error_class)
+  it "raises a FrozenError on a frozen instance that would not be modified" do
+    -> {"hello".freeze.strip! }.should.raise(FrozenError)
+    -> {"".freeze.strip!      }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/sub_spec.rb b/spec/ruby/core/string/sub_spec.rb
index 630f0d6b70..f0082fba59 100644
--- a/spec/ruby/core/string/sub_spec.rb
+++ b/spec/ruby/core/string/sub_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -6,7 +7,7 @@ describe "String#sub with pattern, replacement" do
     a = "hello"
     b = a.sub(/w.*$/, "*")
 
-    b.should_not equal(a)
+    b.should_not.equal?(a)
     b.should == "hello"
   end
 
@@ -137,26 +138,6 @@ describe "String#sub with pattern, replacement" do
     "hello".sub(/./, 'hah\\').should == 'hah\\ello'
   end
 
-  it "taints the result if the original string or replacement is tainted" do
-    hello = "hello"
-    hello_t = "hello"
-    a = "a"
-    a_t = "a"
-    empty = ""
-    empty_t = ""
-
-    hello_t.taint; a_t.taint; empty_t.taint
-
-    hello_t.sub(/./, a).tainted?.should == true
-    hello_t.sub(/./, empty).tainted?.should == true
-
-    hello.sub(/./, a_t).tainted?.should == true
-    hello.sub(/./, empty_t).tainted?.should == true
-    hello.sub(//, empty_t).tainted?.should == true
-
-    hello.sub(//.taint, "foo").tainted?.should == false
-  end
-
   it "tries to convert pattern to a string using to_str" do
     pattern = mock('.')
     pattern.should_receive(:to_str).and_return(".")
@@ -166,16 +147,16 @@ describe "String#sub with pattern, replacement" do
 
   not_supported_on :opal do
     it "raises a TypeError when pattern is a Symbol" do
-      -> { "hello".sub(:woot, "x") }.should raise_error(TypeError)
+      -> { "hello".sub(:woot, "x") }.should.raise(TypeError)
     end
   end
 
   it "raises a TypeError when pattern is an Array" do
-    -> { "hello".sub([], "x") }.should raise_error(TypeError)
+    -> { "hello".sub([], "x") }.should.raise(TypeError)
   end
 
   it "raises a TypeError when pattern can't be converted to a string" do
-    -> { "hello".sub(Object.new, nil) }.should raise_error(TypeError)
+    -> { "hello".sub(Object.new, nil) }.should.raise(TypeError)
   end
 
   it "tries to convert replacement to a string using to_str" do
@@ -186,15 +167,15 @@ describe "String#sub with pattern, replacement" do
   end
 
   it "raises a TypeError when replacement can't be converted to a string" do
-    -> { "hello".sub(/[aeiou]/, []) }.should raise_error(TypeError)
-    -> { "hello".sub(/[aeiou]/, 99) }.should raise_error(TypeError)
+    -> { "hello".sub(/[aeiou]/, []) }.should.raise(TypeError)
+    -> { "hello".sub(/[aeiou]/, 99) }.should.raise(TypeError)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("").sub(//, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("").sub(/foo/, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").sub(/foo/, "").should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("foo").sub("foo", "").should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("").sub(//, "").should.instance_of?(String)
+    StringSpecs::MyString.new("").sub(/foo/, "").should.instance_of?(String)
+    StringSpecs::MyString.new("foo").sub(/foo/, "").should.instance_of?(String)
+    StringSpecs::MyString.new("foo").sub("foo", "").should.instance_of?(String)
   end
 
   it "sets $~ to MatchData of match and nil when there's none" do
@@ -223,6 +204,17 @@ describe "String#sub with pattern, replacement" do
     "ababa".sub(/(b)/, '\\\\\1').should == "a\\baba"
   end
 
+  it "handles a pattern in a superset encoding" do
+    result = 'abc'.force_encoding(Encoding::US_ASCII).sub('é', 'è')
+    result.should == 'abc'
+    result.encoding.should == Encoding::US_ASCII
+  end
+
+  it "handles a pattern in a subset encoding" do
+    result = 'été'.sub('t'.force_encoding(Encoding::US_ASCII), 'u')
+    result.should == 'éué'
+    result.encoding.should == Encoding::UTF_8
+  end
 end
 
 describe "String#sub with pattern and block" do
@@ -240,10 +232,10 @@ describe "String#sub with pattern and block" do
     offsets = []
 
     str.sub(/([aeiou])/) do
-       md = $~
-       md.string.should == str
-       offsets << md.offset(0)
-       str
+      md = $~
+      md.string.should == str
+      offsets << md.offset(0)
+      str
     end.should == "hhellollo"
 
     offsets.should == [[1, 2]]
@@ -284,41 +276,15 @@ describe "String#sub with pattern and block" do
     obj.should_receive(:to_s).and_return("ok")
     "hello".sub(/.+/) { obj }.should == "ok"
   end
-
-  it "taints the result if the original string or replacement is tainted" do
-    hello = "hello"
-    hello_t = "hello"
-    a = "a"
-    a_t = "a"
-    empty = ""
-    empty_t = ""
-
-    hello_t.taint; a_t.taint; empty_t.taint
-
-    hello_t.sub(/./) { a }.tainted?.should == true
-    hello_t.sub(/./) { empty }.tainted?.should == true
-
-    hello.sub(/./) { a_t }.tainted?.should == true
-    hello.sub(/./) { empty_t }.tainted?.should == true
-    hello.sub(//) { empty_t }.tainted?.should == true
-
-    hello.sub(//.taint) { "foo" }.tainted?.should == false
-  end
 end
 
 describe "String#sub! with pattern, replacement" do
   it "modifies self in place and returns self" do
     a = "hello"
-    a.sub!(/[aeiou]/, '*').should equal(a)
+    a.sub!(/[aeiou]/, '*').should.equal?(a)
     a.should == "h*llo"
   end
 
-  it "taints self if replacement is tainted" do
-    a = "hello"
-    a.sub!(/./.taint, "foo").tainted?.should == false
-    a.sub!(/./, "foo".taint).tainted?.should == true
-  end
-
   it "returns nil if no modifications were made" do
     a = "hello"
     a.sub!(/z/, '*').should == nil
@@ -326,20 +292,41 @@ describe "String#sub! with pattern, replacement" do
     a.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     s = "hello"
     s.freeze
 
-    -> { s.sub!(/ROAR/, "x")    }.should raise_error(frozen_error_class)
-    -> { s.sub!(/e/, "e")       }.should raise_error(frozen_error_class)
-    -> { s.sub!(/[aeiou]/, '*') }.should raise_error(frozen_error_class)
+    -> { s.sub!(/ROAR/, "x")    }.should.raise(FrozenError)
+    -> { s.sub!(/e/, "e")       }.should.raise(FrozenError)
+    -> { s.sub!(/[aeiou]/, '*') }.should.raise(FrozenError)
+  end
+
+  it "handles a pattern in a superset encoding" do
+    string = 'abc'.force_encoding(Encoding::US_ASCII)
+
+    result = string.sub!('é', 'è')
+
+    result.should == nil
+    string.should == 'abc'
+    string.encoding.should == Encoding::US_ASCII
+  end
+
+  it "handles a pattern in a subset encoding" do
+    string = 'été'
+    pattern = 't'.force_encoding(Encoding::US_ASCII)
+
+    result = string.sub!(pattern, 'u')
+
+    result.should == string
+    string.should == 'éué'
+    string.encoding.should == Encoding::UTF_8
   end
 end
 
 describe "String#sub! with pattern and block" do
   it "modifies self in place and returns self" do
     a = "hello"
-    a.sub!(/[aeiou]/) { '*' }.should equal(a)
+    a.sub!(/[aeiou]/) { '*' }.should.equal?(a)
     a.should == "h*llo"
   end
 
@@ -352,21 +339,15 @@ describe "String#sub! with pattern and block" do
     offsets = []
 
     str.dup.sub!(/([aeiou])/) do
-       md = $~
-       md.string.should == str
-       offsets << md.offset(0)
-       str
+      md = $~
+      md.string.should == str
+      offsets << md.offset(0)
+      str
     end.should == "hhellollo"
 
     offsets.should == [[1, 2]]
   end
 
-  it "taints self if block's result is tainted" do
-    a = "hello"
-    a.sub!(/./.taint) { "foo" }.tainted?.should == false
-    a.sub!(/./) { "foo".taint }.tainted?.should == true
-  end
-
   it "returns nil if no modifications were made" do
     a = "hello"
     a.sub!(/z/) { '*' }.should == nil
@@ -376,16 +357,16 @@ describe "String#sub! with pattern and block" do
 
   it "raises a RuntimeError if the string is modified while substituting" do
     str = "hello"
-    -> { str.sub!(//) { str << 'x' } }.should raise_error(RuntimeError)
+    -> { str.sub!(//) { str << 'x' } }.should.raise(RuntimeError)
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     s = "hello"
     s.freeze
 
-    -> { s.sub!(/ROAR/) { "x" }    }.should raise_error(frozen_error_class)
-    -> { s.sub!(/e/) { "e" }       }.should raise_error(frozen_error_class)
-    -> { s.sub!(/[aeiou]/) { '*' } }.should raise_error(frozen_error_class)
+    -> { s.sub!(/ROAR/) { "x" }    }.should.raise(FrozenError)
+    -> { s.sub!(/e/) { "e" }       }.should.raise(FrozenError)
+    -> { s.sub!(/[aeiou]/) { '*' } }.should.raise(FrozenError)
   end
 end
 
@@ -452,26 +433,6 @@ describe "String#sub with pattern and Hash" do
     "hello".sub(/(.+)/, 'hello' => repl ).should == repl
   end
 
-  it "untrusts the result if the original string is untrusted" do
-    str = "Ghana".untrust
-    str.sub(/[Aa]na/, 'ana' => '').untrusted?.should be_true
-  end
-
-  it "untrusts the result if a hash value is untrusted" do
-    str = "Ghana"
-    str.sub(/a$/, 'a' => 'di'.untrust).untrusted?.should be_true
-  end
-
-  it "taints the result if the original string is tainted" do
-    str = "Ghana".taint
-    str.sub(/[Aa]na/, 'ana' => '').tainted?.should be_true
-  end
-
-  it "taints the result if a hash value is tainted" do
-    str = "Ghana"
-    str.sub(/a$/, 'a' => 'di'.taint).tainted?.should be_true
-  end
-
 end
 
 describe "String#sub! with pattern and Hash" do
@@ -536,36 +497,16 @@ describe "String#sub! with pattern and Hash" do
     repl = '\& \0 \1 \` \\\' \+ \\\\ foo'
     "hello".sub!(/(.+)/, 'hello' => repl ).should == repl
   end
-
-  it "keeps untrusted state" do
-    str = "Ghana".untrust
-    str.sub!(/[Aa]na/, 'ana' => '').untrusted?.should be_true
-  end
-
-  it "untrusts self if a hash value is untrusted" do
-    str = "Ghana"
-    str.sub!(/a$/, 'a' => 'di'.untrust).untrusted?.should be_true
-  end
-
-  it "keeps tainted state" do
-    str = "Ghana".taint
-    str.sub!(/[Aa]na/, 'ana' => '').tainted?.should be_true
-  end
-
-  it "taints self if a hash value is tainted" do
-    str = "Ghana"
-    str.sub!(/a$/, 'a' => 'di'.taint).tainted?.should be_true
-  end
 end
 
 describe "String#sub with pattern and without replacement and block" do
   it "raises a ArgumentError" do
-    -> { "abca".sub(/a/) }.should raise_error(ArgumentError)
+    -> { "abca".sub(/a/) }.should.raise(ArgumentError)
   end
 end
 
 describe "String#sub! with pattern and without replacement and block" do
   it "raises a ArgumentError" do
-    -> { "abca".sub!(/a/) }.should raise_error(ArgumentError)
+    -> { "abca".sub!(/a/) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/swapcase_spec.rb b/spec/ruby/core/string/swapcase_spec.rb
index 95edcec7d1..f0e6e0182c 100644
--- a/spec/ruby/core/string/swapcase_spec.rb
+++ b/spec/ruby/core/string/swapcase_spec.rb
@@ -1,17 +1,17 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "String#swapcase" do
   it "returns a new string with all uppercase chars from self converted to lowercase and vice versa" do
-   "Hello".swapcase.should == "hELLO"
-   "cYbEr_PuNk11".swapcase.should == "CyBeR_pUnK11"
-   "+++---111222???".swapcase.should == "+++---111222???"
+    "Hello".swapcase.should == "hELLO"
+    "cYbEr_PuNk11".swapcase.should == "CyBeR_pUnK11"
+    "+++---111222???".swapcase.should == "+++---111222???"
   end
 
-  it "taints resulting string when self is tainted" do
-    "".taint.swapcase.tainted?.should == true
-    "hello".taint.swapcase.tainted?.should == true
+  it "returns a String in the same encoding as self" do
+    "Hello".encode("US-ASCII").swapcase.encoding.should == Encoding::US_ASCII
   end
 
   describe "full Unicode case mapping" do
@@ -25,7 +25,7 @@ describe "String#swapcase" do
       swapcased.should == "aSSET"
       swapcased.size.should == 5
       swapcased.bytesize.should == 5
-      swapcased.ascii_only?.should be_true
+      swapcased.ascii_only?.should == true
     end
   end
 
@@ -33,6 +33,10 @@ describe "String#swapcase" do
     it "does not swapcase non-ASCII characters" do
       "aßet".swapcase(:ascii).should == "AßET"
     end
+
+    it "works with substrings" do
+      "prefix aTé"[-3..-1].swapcase(:ascii).should == "Até"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -45,7 +49,7 @@ describe "String#swapcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "aiS".swapcase(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { "aiS".swapcase(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -59,31 +63,37 @@ describe "String#swapcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "aiS".swapcase(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { "aiS".swapcase(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { "abc".swapcase(:fold) }.should raise_error(ArgumentError)
+    -> { "abc".swapcase(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { "abc".swapcase(:invalid_option) }.should raise_error(ArgumentError)
+    -> { "abc".swapcase(:invalid_option) }.should.raise(ArgumentError)
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("").swapcase.should be_an_instance_of(StringSpecs::MyString)
-    StringSpecs::MyString.new("hello").swapcase.should be_an_instance_of(StringSpecs::MyString)
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("").swapcase.should.instance_of?(String)
+    StringSpecs::MyString.new("hello").swapcase.should.instance_of?(String)
   end
 end
 
 describe "String#swapcase!" do
   it "modifies self in place" do
     a = "cYbEr_PuNk11"
-    a.swapcase!.should equal(a)
+    a.swapcase!.should.equal?(a)
     a.should == "CyBeR_pUnK11"
   end
 
+  it "modifies self in place for non-ascii-compatible encodings" do
+    a = "cYbEr_PuNk11".encode("utf-16le")
+    a.swapcase!
+    a.should == "CyBeR_pUnK11".encode("utf-16le")
+  end
+
   describe "full Unicode case mapping" do
     it "modifies self in place for all of Unicode with no option" do
       a = "äÖü"
@@ -91,6 +101,12 @@ describe "String#swapcase!" do
       a.should == "ÄöÜ"
     end
 
+    it "works for non-ascii-compatible encodings" do
+      a = "äÖü".encode("utf-16le")
+      a.swapcase!
+      a.should == "ÄöÜ".encode("utf-16le")
+    end
+
     it "updates string metadata" do
       swapcased = "Aßet"
       swapcased.swapcase!
@@ -98,7 +114,7 @@ describe "String#swapcase!" do
       swapcased.should == "aSSET"
       swapcased.size.should == 5
       swapcased.bytesize.should == 5
-      swapcased.ascii_only?.should be_true
+      swapcased.ascii_only?.should == true
     end
   end
 
@@ -108,6 +124,12 @@ describe "String#swapcase!" do
       a.swapcase!(:ascii)
       a.should == "AßET"
     end
+
+    it "works for non-ascii-compatible encodings" do
+      a = "aBc".encode("utf-16le")
+      a.swapcase!(:ascii)
+      a.should == "AbC".encode("utf-16le")
+    end
   end
 
   describe "modifies self in place for full Unicode case mapping adapted for Turkic languages" do
@@ -124,7 +146,7 @@ describe "String#swapcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "aiS"; a.swapcase!(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "aiS"; a.swapcase!(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -142,16 +164,16 @@ describe "String#swapcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "aiS"; a.swapcase!(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "aiS"; a.swapcase!(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { a = "abc"; a.swapcase!(:fold) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.swapcase!(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { a = "abc"; a.swapcase!(:invalid_option) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.swapcase!(:invalid_option) }.should.raise(ArgumentError)
   end
 
   it "returns nil if no modifications were made" do
@@ -162,10 +184,10 @@ describe "String#swapcase!" do
     "".swapcase!.should == nil
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
+  it "raises a FrozenError when self is frozen" do
     ["", "hello"].each do |a|
       a.freeze
-      -> { a.swapcase! }.should raise_error(frozen_error_class)
+      -> { a.swapcase! }.should.raise(FrozenError)
     end
   end
 end
diff --git a/spec/ruby/core/string/to_c_spec.rb b/spec/ruby/core/string/to_c_spec.rb
index 9c84b14f4d..9cd0ed4401 100644
--- a/spec/ruby/core/string/to_c_spec.rb
+++ b/spec/ruby/core/string/to_c_spec.rb
@@ -1,99 +1,53 @@
 require_relative '../../spec_helper'
+require_relative '../../shared/kernel/complex'
+require_relative 'fixtures/to_c'
 
 describe "String#to_c" do
-  it "returns a Complex object" do
-    '9'.to_c.should be_an_instance_of(Complex)
-  end
-
-  it "understands integers" do
-    '20'.to_c.should == Complex(20)
-  end
-
-  it "understands negative integers" do
-    '-3'.to_c.should == Complex(-3)
-  end
-
-  it "understands fractions (numerator/denominator) for the real part" do
-    '2/3'.to_c.should == Complex(Rational(2, 3))
-  end
-
-  it "understands fractions (numerator/denominator) for the imaginary part" do
-    '4+2/3i'.to_c.should == Complex(4, Rational(2, 3))
-  end
-
-  it "understands negative fractions (-numerator/denominator) for the real part" do
-    '-2/3'.to_c.should == Complex(Rational(-2, 3))
-  end
-
-  it "understands negative fractions (-numerator/denominator) for the imaginary part" do
-    '7-2/3i'.to_c.should == Complex(7, Rational(-2, 3))
-  end
-
-  it "understands floats (a.b) for the real part" do
-    '2.3'.to_c.should == Complex(2.3)
-  end
-
-  it "understands floats (a.b) for the imaginary part" do
-    '4+2.3i'.to_c.should == Complex(4, 2.3)
-  end
-
-  it "understands negative floats (-a.b) for the real part" do
-    '-2.33'.to_c.should == Complex(-2.33)
-  end
-
-  it "understands negative floats (-a.b) for the imaginary part" do
-    '7-28.771i'.to_c.should == Complex(7, -28.771)
-  end
-
-  it "understands an integer followed by 'i' to mean that integer is the imaginary part" do
-    '35i'.to_c.should == Complex(0,35)
-  end
-
-  it "understands a negative integer followed by 'i' to mean that negative integer is the imaginary part" do
-    '-29i'.to_c.should == Complex(0,-29)
-  end
-
-  it "understands an 'i' by itself as denoting a complex number with an imaginary part of 1" do
-    'i'.to_c.should == Complex(0,1)
-  end
-
-  it "understands a '-i' by itself as denoting a complex number with an imaginary part of -1" do
-    '-i'.to_c.should == Complex(0,-1)
-  end
-
-  it "understands 'a+bi' to mean a complex number with 'a' as the real part, 'b' as the imaginary" do
-    '79+4i'.to_c.should == Complex(79,4)
-  end
+  it_behaves_like :kernel_complex, :to_c_method, StringSpecs
+end
 
-  it "understands 'a-bi' to mean a complex number with 'a' as the real part, '-b' as the imaginary" do
-    '79-4i'.to_c.should == Complex(79,-4)
+describe "String#to_c" do
+  it "returns a complex number with 0 as the real part, 0 as the imaginary part for unrecognised Strings" do
+    'ruby'.to_c.should == Complex(0, 0)
   end
 
-  it "understands scientific notation for the real part" do
-    '2e3+4i'.to_c.should == Complex(2e3,4)
+  it "ignores trailing garbage" do
+    '79+4iruby'.to_c.should == Complex(79, 4)
+    '7__9+4__0i'.to_c.should == Complex(7, 0)
   end
 
-  it "understands negative scientific notation for the real part" do
-    '-2e3+4i'.to_c.should == Complex(-2e3,4)
-  end
+  context "it treats special float value strings as characters" do
+    it "parses any string that starts with 'I' as 1i" do
+      'Infinity'.to_c.should == Complex(0, 1)
+      '-Infinity'.to_c.should == Complex(0, -1)
+      'Insecure'.to_c.should == Complex(0, 1)
+      '-Insecure'.to_c.should == Complex(0, -1)
+    end
 
-  it "understands scientific notation for the imaginary part" do
-    '4+2e3i'.to_c.should == Complex(4, 2e3)
+    it "does not parse any numeric information in 'NaN'" do
+      'NaN'.to_c.should == Complex(0, 0)
+    end
   end
 
-  it "understands negative scientific notation for the imaginary part" do
-    '4-2e3i'.to_c.should == Complex(4, -2e3)
+  it "allows null-byte" do
+    "1-2i\0".to_c.should == Complex(1, -2)
+    "1\0-2i".to_c.should == Complex(1, 0)
+    "\01-2i".to_c.should == Complex(0, 0)
   end
 
-  it "understands scientific notation for the real and imaginary part in the same String" do
-    '2e3+2e4i'.to_c.should == Complex(2e3,2e4)
+  it "raises Encoding::CompatibilityError if String is in not ASCII-compatible encoding" do
+    -> {
+      '79+4i'.encode("UTF-16").to_c
+    }.should.raise(Encoding::CompatibilityError, "ASCII incompatible encoding: UTF-16")
   end
 
-  it "understands negative scientific notation for the real and imaginary part in the same String" do
-    '-2e3-2e4i'.to_c.should == Complex(-2e3,-2e4)
-  end
+  it "treats a sequence of underscores as an end of Complex string" do
+    "5+3_1i".to_c.should == Complex(5, 31)
+    "5+3__1i".to_c.should == Complex(5)
+    "5+3___1i".to_c.should == Complex(5)
 
-  it "returns a complex number with 0 as the real part, 0 as the imaginary part for unrecognised Strings" do
-  'ruby'.to_c.should == Complex(0,0)
+    "12_3".to_c.should == Complex(123)
+    "12__3".to_c.should == Complex(12)
+    "12___3".to_c.should == Complex(12)
   end
 end
diff --git a/spec/ruby/core/string/to_f_spec.rb b/spec/ruby/core/string/to_f_spec.rb
index cf64ecfc5d..bb09e4f2f3 100644
--- a/spec/ruby/core/string/to_f_spec.rb
+++ b/spec/ruby/core/string/to_f_spec.rb
@@ -5,16 +5,15 @@ require_relative 'fixtures/classes'
 
 describe "String#to_f" do
   it "treats leading characters of self as a floating point number" do
-   "123.45e1".to_f.should == 1234.5
-   "45.67 degrees".to_f.should == 45.67
-   "0".to_f.should == 0.0
-   "123.45e1".to_f.should == 1234.5
+    "123.45e1".to_f.should == 1234.5
+    "45.67 degrees".to_f.should == 45.67
+    "0".to_f.should == 0.0
 
-   ".5".to_f.should == 0.5
-   ".5e1".to_f.should == 5.0
-   "5.".to_f.should == 5.0
-   "5e".to_f.should == 5.0
-   "5E".to_f.should == 5.0
+    ".5".to_f.should == 0.5
+    ".5e1".to_f.should == 5.0
+    "5.".to_f.should == 5.0
+    "5e".to_f.should == 5.0
+    "5E".to_f.should == 5.0
   end
 
   it "treats special float value strings as characters" do
@@ -43,18 +42,39 @@ describe "String#to_f" do
     "1_234_567.890_1".to_f.should == 1_234_567.890_1
   end
 
-  it "returns 0 for strings with any non-digit in them" do
-    "blah".to_f.should == 0
-    "0b5".to_f.should == 0
-    "0d5".to_f.should == 0
-    "0o5".to_f.should == 0
-    "0xx5".to_f.should == 0
-  end
-
   it "returns 0 for strings with leading underscores" do
     "_9".to_f.should == 0
   end
 
+  it "stops if the underscore is not followed or preceded by a number" do
+    "1__2".to_f.should == 1.0
+    "1_.2".to_f.should == 1.0
+    "1._2".to_f.should == 1.0
+    "1.2_e2".to_f.should == 1.2
+    "1.2e_2".to_f.should == 1.2
+    "1_x2".to_f.should == 1.0
+    "1x_2".to_f.should == 1.0
+    "+_1".to_f.should == 0.0
+    "-_1".to_f.should == 0.0
+  end
+
+  it "does not allow prefixes to autodetect the base" do
+    "0b10".to_f.should == 0
+    "010".to_f.should == 10
+    "0o10".to_f.should == 0
+    "0d10".to_f.should == 0
+    "0x10".to_f.should == 0
+  end
+
+  it "treats any non-numeric character other than '.', 'e' and '_' as terminals" do
+    "blah".to_f.should == 0
+    "1b5".to_f.should == 1
+    "1d5".to_f.should == 1
+    "1o5".to_f.should == 1
+    "1xx5".to_f.should == 1
+    "x5".to_f.should == 0
+  end
+
   it "takes an optional sign" do
     "-45.67 degrees".to_f.should == -45.67
     "+45.67 degrees".to_f.should == 45.67
@@ -63,8 +83,58 @@ describe "String#to_f" do
     (1.0 / "-0".to_f).to_s.should == "-Infinity"
   end
 
+  it "treats a second 'e' as terminal" do
+    "1.234e1e2".to_f.should == 1.234e1
+  end
+
+  it "treats a second '.' as terminal" do
+    "1.2.3".to_f.should == 1.2
+  end
+
+  it "treats a '.' after an 'e' as terminal" do
+    "1.234e1.9".to_f.should == 1.234e1
+  end
+
   it "returns 0.0 if the conversion fails" do
     "bad".to_f.should == 0.0
     "thx1138".to_f.should == 0.0
   end
+
+  it "ignores leading and trailing whitespace" do
+    "  1.2".to_f.should == 1.2
+    "1.2  ".to_f.should == 1.2
+    " 1.2 ".to_f.should == 1.2
+    "\t1.2".to_f.should == 1.2
+    "\n1.2".to_f.should == 1.2
+    "\v1.2".to_f.should == 1.2
+    "\f1.2".to_f.should == 1.2
+    "\r1.2".to_f.should == 1.2
+  end
+
+  it "treats non-printable ASCII characters as terminals" do
+    "\0001.2".to_f.should == 0
+    "\0011.2".to_f.should == 0
+    "\0371.2".to_f.should == 0
+    "\1771.2".to_f.should == 0
+    "\2001.2".b.to_f.should == 0
+    "\3771.2".b.to_f.should == 0
+  end
+
+  it "raises Encoding::CompatibilityError if String is in not ASCII-compatible encoding" do
+    -> {
+      '1.2'.encode("UTF-16").to_f
+    }.should.raise(Encoding::CompatibilityError, "ASCII incompatible encoding: UTF-16")
+  end
+
+  it "allows String representation without a fractional part" do
+    "1.".to_f.should == 1.0
+    "+1.".to_f.should == 1.0
+    "-1.".to_f.should == -1.0
+    "1.e+0".to_f.should == 1.0
+    "1.e+0".to_f.should == 1.0
+
+    ruby_bug "#20705", ""..."3.4" do
+      "1.e-2".to_f.should be_close(0.01, TOLERANCE)
+    end
+  end
 end
diff --git a/spec/ruby/core/string/to_i_spec.rb b/spec/ruby/core/string/to_i_spec.rb
index a37be47778..629750bd73 100644
--- a/spec/ruby/core/string/to_i_spec.rb
+++ b/spec/ruby/core/string/to_i_spec.rb
@@ -10,6 +10,18 @@ describe "String#to_i" do
     "1_2_3asdf".to_i.should == 123
   end
 
+  it "ignores multiple non-consecutive underscores when the first digit is 0" do
+    (2..16).each do |base|
+      "0_0_010".to_i(base).should == base;
+    end
+  end
+
+  it "bails out at the first double underscore if the first digit is 0" do
+    (2..16).each do |base|
+      "010__1".to_i(base).should == base;
+    end
+  end
+
   it "ignores leading whitespaces" do
     [ " 123", "     123", "\r\n\r\n123", "\t\t123",
       "\r\n\t\n123", " \t\n\r\t 123"].each do |str|
@@ -126,34 +138,34 @@ describe "String#to_i" do
   end
 
   it "raises an ArgumentError for illegal bases (1, < 0 or > 36)" do
-    -> { "".to_i(1)  }.should raise_error(ArgumentError)
-    -> { "".to_i(-1) }.should raise_error(ArgumentError)
-    -> { "".to_i(37) }.should raise_error(ArgumentError)
+    -> { "".to_i(1)  }.should.raise(ArgumentError)
+    -> { "".to_i(-1) }.should.raise(ArgumentError)
+    -> { "".to_i(37) }.should.raise(ArgumentError)
   end
 
-  it "returns a Fixnum for long strings with trailing spaces" do
+  it "returns an Integer for long strings with trailing spaces" do
     "0                             ".to_i.should == 0
-    "0                             ".to_i.should be_an_instance_of(Fixnum)
+    "0                             ".to_i.should.instance_of?(Integer)
 
     "10                             ".to_i.should == 10
-    "10                             ".to_i.should be_an_instance_of(Fixnum)
+    "10                             ".to_i.should.instance_of?(Integer)
 
     "-10                            ".to_i.should == -10
-    "-10                            ".to_i.should be_an_instance_of(Fixnum)
+    "-10                            ".to_i.should.instance_of?(Integer)
   end
 
-  it "returns a Fixnum for long strings with leading spaces" do
+  it "returns an Integer for long strings with leading spaces" do
     "                             0".to_i.should == 0
-    "                             0".to_i.should be_an_instance_of(Fixnum)
+    "                             0".to_i.should.instance_of?(Integer)
 
     "                             10".to_i.should == 10
-    "                             10".to_i.should be_an_instance_of(Fixnum)
+    "                             10".to_i.should.instance_of?(Integer)
 
     "                            -10".to_i.should == -10
-    "                            -10".to_i.should be_an_instance_of(Fixnum)
+    "                            -10".to_i.should.instance_of?(Integer)
   end
 
-  it "returns the correct Bignum for long strings" do
+  it "returns the correct Integer for long strings" do
     "245789127594125924165923648312749312749327482".to_i.should == 245789127594125924165923648312749312749327482
     "-245789127594125924165923648312749312749327482".to_i.should == -245789127594125924165923648312749312749327482
   end
diff --git a/spec/ruby/core/string/to_r_spec.rb b/spec/ruby/core/string/to_r_spec.rb
index 7e1d635d3b..fb7c9d108e 100644
--- a/spec/ruby/core/string/to_r_spec.rb
+++ b/spec/ruby/core/string/to_r_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "String#to_r" do
   it "returns a Rational object" do
-    String.new.to_r.should be_an_instance_of(Rational)
+    String.new.to_r.should.instance_of?(Rational)
   end
 
   it "returns (0/1) for the empty String" do
@@ -33,6 +33,10 @@ describe "String#to_r" do
     "-20".to_r.should == Rational(-20, 1)
   end
 
+  it "accepts leading plus signs" do
+    "+20".to_r.should == Rational(20, 1)
+  end
+
   it "does not treat a leading period without a numeric prefix as a decimal point" do
     ".9".to_r.should_not == Rational(8106479329266893, 9007199254740992)
   end
diff --git a/spec/ruby/core/string/tr_s_spec.rb b/spec/ruby/core/string/tr_s_spec.rb
index 4380f2d548..22a193ec4b 100644
--- a/spec/ruby/core/string/tr_s_spec.rb
+++ b/spec/ruby/core/string/tr_s_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -17,6 +18,13 @@ describe "String#tr_s" do
     "hello ^--^".tr_s("---", "_").should == "hello ^_^"
   end
 
+  it "accepts c1-c1 notation to denote range of one character" do
+    "hello".tr_s('e-e', 'x').should == "hxllo"
+    "123456789".tr_s("2-23","xy").should == "1xy456789"
+    "hello ^-^".tr_s("e-", "a-a_").should == "hallo ^_^"
+    "hello ^-^".tr_s("---o", "_a").should == "hella ^_^"
+  end
+
   it "pads to_str with its last char if it is shorter than from_string" do
     "this".tr_s("this", "x").should == "x"
   end
@@ -45,19 +53,8 @@ describe "String#tr_s" do
     "bla".tr_s(from_str, to_str).should == "BlA"
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("hello").tr_s("e", "a").should be_an_instance_of(StringSpecs::MyString)
-  end
-
-  it "taints the result when self is tainted" do
-    ["h", "hello"].each do |str|
-      tainted_str = str.dup.taint
-
-      tainted_str.tr_s("e", "a").tainted?.should == true
-
-      str.tr_s("e".taint, "a").tainted?.should == false
-      str.tr_s("e", "a".taint).tainted?.should == false
-    end
+  it "returns String instances when called on a subclass" do
+    StringSpecs::MyString.new("hello").tr_s("e", "a").should.instance_of?(String)
   end
 
   # http://redmine.ruby-lang.org/issues/show/1839
@@ -125,10 +122,10 @@ describe "String#tr_s!" do
     s.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     s = "hello".freeze
-    -> { s.tr_s!("el", "ar") }.should raise_error(frozen_error_class)
-    -> { s.tr_s!("l", "r")   }.should raise_error(frozen_error_class)
-    -> { s.tr_s!("", "")     }.should raise_error(frozen_error_class)
+    -> { s.tr_s!("el", "ar") }.should.raise(FrozenError)
+    -> { s.tr_s!("l", "r")   }.should.raise(FrozenError)
+    -> { s.tr_s!("", "")     }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/tr_spec.rb b/spec/ruby/core/string/tr_spec.rb
index 721ebab51c..cb57c3851e 100644
--- a/spec/ruby/core/string/tr_spec.rb
+++ b/spec/ruby/core/string/tr_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -16,17 +17,24 @@ describe "String#tr" do
     "hello ^-^".tr("---", "_").should == "hello ^_^"
   end
 
+  it "accepts c1-c1 notation to denote range of one character" do
+    "hello".tr('e-e', 'x').should == "hxllo"
+    "123456789".tr("2-23","xy").should == "1xy456789"
+    "hello ^-^".tr("e-", "a-a_").should == "hallo ^_^"
+    "hello ^-^".tr("---o", "_a").should == "hella ^_^"
+  end
+
   it "pads to_str with its last char if it is shorter than from_string" do
     "this".tr("this", "x").should == "xxxx"
     "hello".tr("a-z", "A-H.").should == "HE..."
   end
 
   it "raises an ArgumentError a descending range in the replacement as containing just the start character" do
-    -> { "hello".tr("a-y", "z-b") }.should raise_error(ArgumentError)
+    -> { "hello".tr("a-y", "z-b") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError a descending range in the source as empty" do
-    -> { "hello".tr("l-a", "z") }.should raise_error(ArgumentError)
+    -> { "hello".tr("l-a", "z") }.should.raise(ArgumentError)
   end
 
   it "translates chars not in from_string when it starts with a ^" do
@@ -57,19 +65,8 @@ describe "String#tr" do
     "bla".tr(from_str, to_str).should == "BlA"
   end
 
-  it "returns subclass instances when called on a subclass" do
-    StringSpecs::MyString.new("hello").tr("e", "a").should be_an_instance_of(StringSpecs::MyString)
-  end
-
-  it "taints the result when self is tainted" do
-    ["h", "hello"].each do |str|
-      tainted_str = str.dup.taint
-
-      tainted_str.tr("e", "a").tainted?.should == true
-
-      str.tr("e".taint, "a").tainted?.should == false
-      str.tr("e", "a".taint).tainted?.should == false
-    end
+  it "returns Stringinstances when called on a subclass" do
+    StringSpecs::MyString.new("hello").tr("e", "a").should.instance_of?(String)
   end
 
   # http://redmine.ruby-lang.org/issues/show/1839
@@ -120,10 +117,10 @@ describe "String#tr!" do
     s.should == "hello"
   end
 
-  it "raises a #{frozen_error_class} if self is frozen" do
+  it "raises a FrozenError if self is frozen" do
     s = "abcdefghijklmnopqR".freeze
-    -> { s.tr!("cdefg", "12") }.should raise_error(frozen_error_class)
-    -> { s.tr!("R", "S")      }.should raise_error(frozen_error_class)
-    -> { s.tr!("", "")        }.should raise_error(frozen_error_class)
+    -> { s.tr!("cdefg", "12") }.should.raise(FrozenError)
+    -> { s.tr!("R", "S")      }.should.raise(FrozenError)
+    -> { s.tr!("", "")        }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/try_convert_spec.rb b/spec/ruby/core/string/try_convert_spec.rb
index 84415c4a75..0c0219cd2e 100644
--- a/spec/ruby/core/string/try_convert_spec.rb
+++ b/spec/ruby/core/string/try_convert_spec.rb
@@ -4,47 +4,47 @@ require_relative 'fixtures/classes'
 describe "String.try_convert" do
   it "returns the argument if it's a String" do
     x = String.new
-    String.try_convert(x).should equal(x)
+    String.try_convert(x).should.equal?(x)
   end
 
   it "returns the argument if it's a kind of String" do
     x = StringSpecs::MyString.new
-    String.try_convert(x).should equal(x)
+    String.try_convert(x).should.equal?(x)
   end
 
   it "returns nil when the argument does not respond to #to_str" do
-    String.try_convert(Object.new).should be_nil
+    String.try_convert(Object.new).should == nil
   end
 
   it "sends #to_str to the argument and returns the result if it's nil" do
     obj = mock("to_str")
     obj.should_receive(:to_str).and_return(nil)
-    String.try_convert(obj).should be_nil
+    String.try_convert(obj).should == nil
   end
 
   it "sends #to_str to the argument and returns the result if it's a String" do
     x = String.new
     obj = mock("to_str")
     obj.should_receive(:to_str).and_return(x)
-    String.try_convert(obj).should equal(x)
+    String.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_str to the argument and returns the result if it's a kind of String" do
     x = StringSpecs::MyString.new
     obj = mock("to_str")
     obj.should_receive(:to_str).and_return(x)
-    String.try_convert(obj).should equal(x)
+    String.try_convert(obj).should.equal?(x)
   end
 
   it "sends #to_str to the argument and raises TypeError if it's not a kind of String" do
     obj = mock("to_str")
     obj.should_receive(:to_str).and_return(Object.new)
-    -> { String.try_convert obj }.should raise_error(TypeError)
+    -> { String.try_convert obj }.should raise_consistent_error(TypeError, "can't convert MockObject into String (MockObject#to_str gives Object)")
   end
 
   it "does not rescue exceptions raised by #to_str" do
     obj = mock("to_str")
     obj.should_receive(:to_str).and_raise(RuntimeError)
-    -> { String.try_convert obj }.should raise_error(RuntimeError)
+    -> { String.try_convert obj }.should.raise(RuntimeError)
   end
 end
diff --git a/spec/ruby/core/string/uminus_spec.rb b/spec/ruby/core/string/uminus_spec.rb
index dace04846c..46d88f6704 100644
--- a/spec/ruby/core/string/uminus_spec.rb
+++ b/spec/ruby/core/string/uminus_spec.rb
@@ -1,74 +1,6 @@
 require_relative '../../spec_helper'
+require_relative 'shared/dedup'
 
 describe 'String#-@' do
-  it 'returns self if the String is frozen' do
-    input  = 'foo'.freeze
-    output = -input
-
-    output.should equal(input)
-    output.frozen?.should == true
-  end
-
-  it 'returns a frozen copy if the String is not frozen' do
-    input  = 'foo'
-    output = -input
-
-    output.frozen?.should == true
-    output.should_not equal(input)
-    output.should == 'foo'
-  end
-
-  ruby_version_is "2.5" do
-    it "returns the same object for equal unfrozen strings" do
-      origin = "this is a string"
-      dynamic = %w(this is a string).join(' ')
-
-      origin.should_not equal(dynamic)
-      (-origin).should equal(-dynamic)
-    end
-
-    it "returns the same object when it's called on the same String literal" do
-      (-"unfrozen string").should equal(-"unfrozen string")
-      (-"unfrozen string").should_not equal(-"another unfrozen string")
-    end
-  end
-
-  ruby_version_is "2.5"..."2.6" do
-    it "does not deduplicate already frozen strings" do
-      dynamic = %w(this string is frozen).join(' ').freeze
-
-      dynamic.should_not equal("this string is frozen".freeze)
-
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-
-    it "does not deduplicate tainted strings" do
-      dynamic = %w(this string is frozen).join(' ')
-      dynamic.taint
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-
-    it "does not deduplicate strings with additional instance variables" do
-      dynamic = %w(this string is frozen).join(' ')
-      dynamic.instance_variable_set(:@foo, :bar)
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "deduplicates frozen strings" do
-      dynamic = %w(this string is frozen).join(' ').freeze
-
-      dynamic.should_not equal("this string is frozen".freeze)
-
-      (-dynamic).should equal("this string is frozen".freeze)
-      (-dynamic).should equal(-"this string is frozen".freeze)
-    end
-  end
+  it_behaves_like :string_dedup, :-@
 end
diff --git a/spec/ruby/core/string/undump_spec.rb b/spec/ruby/core/string/undump_spec.rb
index 315d27cad4..8516e24b3b 100644
--- a/spec/ruby/core/string/undump_spec.rb
+++ b/spec/ruby/core/string/undump_spec.rb
@@ -2,450 +2,440 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is '2.5' do
-  describe "String#undump" do
-    it "taints the result if self is tainted" do
-      '"foo"'.taint.undump.tainted?.should == true
-    end
+describe "String#undump" do
+  it "does not take into account if a string is frozen" do
+    '"foo"'.freeze.undump.should_not.frozen?
+  end
 
-    it "untrusts the result if self is untrusted" do
-      '"foo"'.untrust.undump.untrusted?.should == true
-    end
+  it "always returns String instance" do
+    StringSpecs::MyString.new('"foo"').undump.should.instance_of?(String)
+  end
 
-    it "does not take into account if a string is frozen" do
-      '"foo"'.freeze.undump.frozen?.should == false
-    end
+  it "strips outer \"" do
+    '"foo"'.undump.should == 'foo'
+  end
 
-    it "always returns String instance" do
-      StringSpecs::MyString.new('"foo"').undump.should be_an_instance_of(String)
-    end
+  it "returns a string with special characters in \\<char> notation replaced with the characters" do
+    [ ['"\\a"', "\a"],
+      ['"\\b"', "\b"],
+      ['"\\t"', "\t"],
+      ['"\\n"', "\n"],
+      ['"\\v"', "\v"],
+      ['"\\f"', "\f"],
+      ['"\\r"', "\r"],
+      ['"\\e"', "\e"]
+    ].should be_computed_by(:undump)
+  end
 
-    it "strips outer \"" do
-      '"foo"'.undump.should == 'foo'
-    end
+  it "returns a string with unescaped sequences \" and \\" do
+    [ ['"\\""' , "\""],
+      ['"\\\\"', "\\"]
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with special characters in \\<char> notation replaced with the characters" do
-      [ ['"\\a"', "\a"],
-        ['"\\b"', "\b"],
-        ['"\\t"', "\t"],
-        ['"\\n"', "\n"],
-        ['"\\v"', "\v"],
-        ['"\\f"', "\f"],
-        ['"\\r"', "\r"],
-        ['"\\e"', "\e"]
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with unescaped sequences \\#<char> when # is followed by $, @, {" do
+    [ ['"\\#$PATH"', "\#$PATH"],
+      ['"\\#@a"',    "\#@a"],
+      ['"\\#@@a"',   "\#@@a"],
+      ['"\\#{a}"',   "\#{a}"]
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with unescaped sequencies \" and \\" do
-      [ ['"\\""' , "\""],
-        ['"\\\\"', "\\"]
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with # not escaped when followed by any other character" do
+    [ ['"#"', '#'],
+      ['"#1"', '#1']
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with unescaped sequences \\#<char> when # is followed by $, @, {" do
-      [ ['"\\#$PATH"', "\#$PATH"],
-        ['"\\#@a"',    "\#@a"],
-        ['"\\#@@a"',   "\#@@a"],
-        ['"\\#{a}"',   "\#{a}"]
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with printable non-alphanumeric characters" do
+    [ ['" "', ' '],
+      ['"!"', '!'],
+      ['"$"', '$'],
+      ['"%"', '%'],
+      ['"&"', '&'],
+      ['"\'"', '\''],
+      ['"("', '('],
+      ['")"', ')'],
+      ['"*"', '*'],
+      ['"+"', '+'],
+      ['","', ','],
+      ['"-"', '-'],
+      ['"."', '.'],
+      ['"/"', '/'],
+      ['":"', ':'],
+      ['";"', ';'],
+      ['"<"', '<'],
+      ['"="', '='],
+      ['">"', '>'],
+      ['"?"', '?'],
+      ['"@"', '@'],
+      ['"["', '['],
+      ['"]"', ']'],
+      ['"^"', '^'],
+      ['"_"', '_'],
+      ['"`"', '`'],
+      ['"{"', '{'],
+      ['"|"', '|'],
+      ['"}"', '}'],
+      ['"~"', '~']
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with # not escaped when followed by any other character" do
-      [ ['"#"', '#'],
-        ['"#1"', '#1']
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with numeric characters unescaped" do
+    [ ['"0"', "0"],
+      ['"1"', "1"],
+      ['"2"', "2"],
+      ['"3"', "3"],
+      ['"4"', "4"],
+      ['"5"', "5"],
+      ['"6"', "6"],
+      ['"7"', "7"],
+      ['"8"', "8"],
+      ['"9"', "9"],
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with printable non-alphanumeric characters" do
-      [ ['" "', ' '],
-        ['"!"', '!'],
-        ['"$"', '$'],
-        ['"%"', '%'],
-        ['"&"', '&'],
-        ['"\'"', '\''],
-        ['"("', '('],
-        ['")"', ')'],
-        ['"*"', '*'],
-        ['"+"', '+'],
-        ['","', ','],
-        ['"-"', '-'],
-        ['"."', '.'],
-        ['"/"', '/'],
-        ['":"', ':'],
-        ['";"', ';'],
-        ['"<"', '<'],
-        ['"="', '='],
-        ['">"', '>'],
-        ['"?"', '?'],
-        ['"@"', '@'],
-        ['"["', '['],
-        ['"]"', ']'],
-        ['"^"', '^'],
-        ['"_"', '_'],
-        ['"`"', '`'],
-        ['"{"', '{'],
-        ['"|"', '|'],
-        ['"}"', '}'],
-        ['"~"', '~']
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with upper-case alpha characters unescaped" do
+    [ ['"A"', 'A'],
+      ['"B"', 'B'],
+      ['"C"', 'C'],
+      ['"D"', 'D'],
+      ['"E"', 'E'],
+      ['"F"', 'F'],
+      ['"G"', 'G'],
+      ['"H"', 'H'],
+      ['"I"', 'I'],
+      ['"J"', 'J'],
+      ['"K"', 'K'],
+      ['"L"', 'L'],
+      ['"M"', 'M'],
+      ['"N"', 'N'],
+      ['"O"', 'O'],
+      ['"P"', 'P'],
+      ['"Q"', 'Q'],
+      ['"R"', 'R'],
+      ['"S"', 'S'],
+      ['"T"', 'T'],
+      ['"U"', 'U'],
+      ['"V"', 'V'],
+      ['"W"', 'W'],
+      ['"X"', 'X'],
+      ['"Y"', 'Y'],
+      ['"Z"', 'Z']
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with numeric characters unescaped" do
-      [ ['"0"', "0"],
-        ['"1"', "1"],
-        ['"2"', "2"],
-        ['"3"', "3"],
-        ['"4"', "4"],
-        ['"5"', "5"],
-        ['"6"', "6"],
-        ['"7"', "7"],
-        ['"8"', "8"],
-        ['"9"', "9"],
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with lower-case alpha characters unescaped" do
+    [ ['"a"', 'a'],
+      ['"b"', 'b'],
+      ['"c"', 'c'],
+      ['"d"', 'd'],
+      ['"e"', 'e'],
+      ['"f"', 'f'],
+      ['"g"', 'g'],
+      ['"h"', 'h'],
+      ['"i"', 'i'],
+      ['"j"', 'j'],
+      ['"k"', 'k'],
+      ['"l"', 'l'],
+      ['"m"', 'm'],
+      ['"n"', 'n'],
+      ['"o"', 'o'],
+      ['"p"', 'p'],
+      ['"q"', 'q'],
+      ['"r"', 'r'],
+      ['"s"', 's'],
+      ['"t"', 't'],
+      ['"u"', 'u'],
+      ['"v"', 'v'],
+      ['"w"', 'w'],
+      ['"x"', 'x'],
+      ['"y"', 'y'],
+      ['"z"', 'z']
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with upper-case alpha characters unescaped" do
-      [ ['"A"', 'A'],
-        ['"B"', 'B'],
-        ['"C"', 'C'],
-        ['"D"', 'D'],
-        ['"E"', 'E'],
-        ['"F"', 'F'],
-        ['"G"', 'G'],
-        ['"H"', 'H'],
-        ['"I"', 'I'],
-        ['"J"', 'J'],
-        ['"K"', 'K'],
-        ['"L"', 'L'],
-        ['"M"', 'M'],
-        ['"N"', 'N'],
-        ['"O"', 'O'],
-        ['"P"', 'P'],
-        ['"Q"', 'Q'],
-        ['"R"', 'R'],
-        ['"S"', 'S'],
-        ['"T"', 'T'],
-        ['"U"', 'U'],
-        ['"V"', 'V'],
-        ['"W"', 'W'],
-        ['"X"', 'X'],
-        ['"Y"', 'Y'],
-        ['"Z"', 'Z']
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with \\x notation replaced with non-printing ASCII character" do
+    [ ['"\\x00"', 0000.chr.force_encoding('utf-8')],
+      ['"\\x01"', 0001.chr.force_encoding('utf-8')],
+      ['"\\x02"', 0002.chr.force_encoding('utf-8')],
+      ['"\\x03"', 0003.chr.force_encoding('utf-8')],
+      ['"\\x04"', 0004.chr.force_encoding('utf-8')],
+      ['"\\x05"', 0005.chr.force_encoding('utf-8')],
+      ['"\\x06"', 0006.chr.force_encoding('utf-8')],
+      ['"\\x0E"', 0016.chr.force_encoding('utf-8')],
+      ['"\\x0F"', 0017.chr.force_encoding('utf-8')],
+      ['"\\x10"', 0020.chr.force_encoding('utf-8')],
+      ['"\\x11"', 0021.chr.force_encoding('utf-8')],
+      ['"\\x12"', 0022.chr.force_encoding('utf-8')],
+      ['"\\x13"', 0023.chr.force_encoding('utf-8')],
+      ['"\\x14"', 0024.chr.force_encoding('utf-8')],
+      ['"\\x15"', 0025.chr.force_encoding('utf-8')],
+      ['"\\x16"', 0026.chr.force_encoding('utf-8')],
+      ['"\\x17"', 0027.chr.force_encoding('utf-8')],
+      ['"\\x18"', 0030.chr.force_encoding('utf-8')],
+      ['"\\x19"', 0031.chr.force_encoding('utf-8')],
+      ['"\\x1A"', 0032.chr.force_encoding('utf-8')],
+      ['"\\x1C"', 0034.chr.force_encoding('utf-8')],
+      ['"\\x1D"', 0035.chr.force_encoding('utf-8')],
+      ['"\\x1E"', 0036.chr.force_encoding('utf-8')],
+      ['"\\x1F"', 0037.chr.force_encoding('utf-8')],
+      ['"\\x7F"', 0177.chr.force_encoding('utf-8')],
+      ['"\\x80"', 0200.chr.force_encoding('utf-8')],
+      ['"\\x81"', 0201.chr.force_encoding('utf-8')],
+      ['"\\x82"', 0202.chr.force_encoding('utf-8')],
+      ['"\\x83"', 0203.chr.force_encoding('utf-8')],
+      ['"\\x84"', 0204.chr.force_encoding('utf-8')],
+      ['"\\x85"', 0205.chr.force_encoding('utf-8')],
+      ['"\\x86"', 0206.chr.force_encoding('utf-8')],
+      ['"\\x87"', 0207.chr.force_encoding('utf-8')],
+      ['"\\x88"', 0210.chr.force_encoding('utf-8')],
+      ['"\\x89"', 0211.chr.force_encoding('utf-8')],
+      ['"\\x8A"', 0212.chr.force_encoding('utf-8')],
+      ['"\\x8B"', 0213.chr.force_encoding('utf-8')],
+      ['"\\x8C"', 0214.chr.force_encoding('utf-8')],
+      ['"\\x8D"', 0215.chr.force_encoding('utf-8')],
+      ['"\\x8E"', 0216.chr.force_encoding('utf-8')],
+      ['"\\x8F"', 0217.chr.force_encoding('utf-8')],
+      ['"\\x90"', 0220.chr.force_encoding('utf-8')],
+      ['"\\x91"', 0221.chr.force_encoding('utf-8')],
+      ['"\\x92"', 0222.chr.force_encoding('utf-8')],
+      ['"\\x93"', 0223.chr.force_encoding('utf-8')],
+      ['"\\x94"', 0224.chr.force_encoding('utf-8')],
+      ['"\\x95"', 0225.chr.force_encoding('utf-8')],
+      ['"\\x96"', 0226.chr.force_encoding('utf-8')],
+      ['"\\x97"', 0227.chr.force_encoding('utf-8')],
+      ['"\\x98"', 0230.chr.force_encoding('utf-8')],
+      ['"\\x99"', 0231.chr.force_encoding('utf-8')],
+      ['"\\x9A"', 0232.chr.force_encoding('utf-8')],
+      ['"\\x9B"', 0233.chr.force_encoding('utf-8')],
+      ['"\\x9C"', 0234.chr.force_encoding('utf-8')],
+      ['"\\x9D"', 0235.chr.force_encoding('utf-8')],
+      ['"\\x9E"', 0236.chr.force_encoding('utf-8')],
+      ['"\\x9F"', 0237.chr.force_encoding('utf-8')],
+      ['"\\xA0"', 0240.chr.force_encoding('utf-8')],
+      ['"\\xA1"', 0241.chr.force_encoding('utf-8')],
+      ['"\\xA2"', 0242.chr.force_encoding('utf-8')],
+      ['"\\xA3"', 0243.chr.force_encoding('utf-8')],
+      ['"\\xA4"', 0244.chr.force_encoding('utf-8')],
+      ['"\\xA5"', 0245.chr.force_encoding('utf-8')],
+      ['"\\xA6"', 0246.chr.force_encoding('utf-8')],
+      ['"\\xA7"', 0247.chr.force_encoding('utf-8')],
+      ['"\\xA8"', 0250.chr.force_encoding('utf-8')],
+      ['"\\xA9"', 0251.chr.force_encoding('utf-8')],
+      ['"\\xAA"', 0252.chr.force_encoding('utf-8')],
+      ['"\\xAB"', 0253.chr.force_encoding('utf-8')],
+      ['"\\xAC"', 0254.chr.force_encoding('utf-8')],
+      ['"\\xAD"', 0255.chr.force_encoding('utf-8')],
+      ['"\\xAE"', 0256.chr.force_encoding('utf-8')],
+      ['"\\xAF"', 0257.chr.force_encoding('utf-8')],
+      ['"\\xB0"', 0260.chr.force_encoding('utf-8')],
+      ['"\\xB1"', 0261.chr.force_encoding('utf-8')],
+      ['"\\xB2"', 0262.chr.force_encoding('utf-8')],
+      ['"\\xB3"', 0263.chr.force_encoding('utf-8')],
+      ['"\\xB4"', 0264.chr.force_encoding('utf-8')],
+      ['"\\xB5"', 0265.chr.force_encoding('utf-8')],
+      ['"\\xB6"', 0266.chr.force_encoding('utf-8')],
+      ['"\\xB7"', 0267.chr.force_encoding('utf-8')],
+      ['"\\xB8"', 0270.chr.force_encoding('utf-8')],
+      ['"\\xB9"', 0271.chr.force_encoding('utf-8')],
+      ['"\\xBA"', 0272.chr.force_encoding('utf-8')],
+      ['"\\xBB"', 0273.chr.force_encoding('utf-8')],
+      ['"\\xBC"', 0274.chr.force_encoding('utf-8')],
+      ['"\\xBD"', 0275.chr.force_encoding('utf-8')],
+      ['"\\xBE"', 0276.chr.force_encoding('utf-8')],
+      ['"\\xBF"', 0277.chr.force_encoding('utf-8')],
+      ['"\\xC0"', 0300.chr.force_encoding('utf-8')],
+      ['"\\xC1"', 0301.chr.force_encoding('utf-8')],
+      ['"\\xC2"', 0302.chr.force_encoding('utf-8')],
+      ['"\\xC3"', 0303.chr.force_encoding('utf-8')],
+      ['"\\xC4"', 0304.chr.force_encoding('utf-8')],
+      ['"\\xC5"', 0305.chr.force_encoding('utf-8')],
+      ['"\\xC6"', 0306.chr.force_encoding('utf-8')],
+      ['"\\xC7"', 0307.chr.force_encoding('utf-8')],
+      ['"\\xC8"', 0310.chr.force_encoding('utf-8')],
+      ['"\\xC9"', 0311.chr.force_encoding('utf-8')],
+      ['"\\xCA"', 0312.chr.force_encoding('utf-8')],
+      ['"\\xCB"', 0313.chr.force_encoding('utf-8')],
+      ['"\\xCC"', 0314.chr.force_encoding('utf-8')],
+      ['"\\xCD"', 0315.chr.force_encoding('utf-8')],
+      ['"\\xCE"', 0316.chr.force_encoding('utf-8')],
+      ['"\\xCF"', 0317.chr.force_encoding('utf-8')],
+      ['"\\xD0"', 0320.chr.force_encoding('utf-8')],
+      ['"\\xD1"', 0321.chr.force_encoding('utf-8')],
+      ['"\\xD2"', 0322.chr.force_encoding('utf-8')],
+      ['"\\xD3"', 0323.chr.force_encoding('utf-8')],
+      ['"\\xD4"', 0324.chr.force_encoding('utf-8')],
+      ['"\\xD5"', 0325.chr.force_encoding('utf-8')],
+      ['"\\xD6"', 0326.chr.force_encoding('utf-8')],
+      ['"\\xD7"', 0327.chr.force_encoding('utf-8')],
+      ['"\\xD8"', 0330.chr.force_encoding('utf-8')],
+      ['"\\xD9"', 0331.chr.force_encoding('utf-8')],
+      ['"\\xDA"', 0332.chr.force_encoding('utf-8')],
+      ['"\\xDB"', 0333.chr.force_encoding('utf-8')],
+      ['"\\xDC"', 0334.chr.force_encoding('utf-8')],
+      ['"\\xDD"', 0335.chr.force_encoding('utf-8')],
+      ['"\\xDE"', 0336.chr.force_encoding('utf-8')],
+      ['"\\xDF"', 0337.chr.force_encoding('utf-8')],
+      ['"\\xE0"', 0340.chr.force_encoding('utf-8')],
+      ['"\\xE1"', 0341.chr.force_encoding('utf-8')],
+      ['"\\xE2"', 0342.chr.force_encoding('utf-8')],
+      ['"\\xE3"', 0343.chr.force_encoding('utf-8')],
+      ['"\\xE4"', 0344.chr.force_encoding('utf-8')],
+      ['"\\xE5"', 0345.chr.force_encoding('utf-8')],
+      ['"\\xE6"', 0346.chr.force_encoding('utf-8')],
+      ['"\\xE7"', 0347.chr.force_encoding('utf-8')],
+      ['"\\xE8"', 0350.chr.force_encoding('utf-8')],
+      ['"\\xE9"', 0351.chr.force_encoding('utf-8')],
+      ['"\\xEA"', 0352.chr.force_encoding('utf-8')],
+      ['"\\xEB"', 0353.chr.force_encoding('utf-8')],
+      ['"\\xEC"', 0354.chr.force_encoding('utf-8')],
+      ['"\\xED"', 0355.chr.force_encoding('utf-8')],
+      ['"\\xEE"', 0356.chr.force_encoding('utf-8')],
+      ['"\\xEF"', 0357.chr.force_encoding('utf-8')],
+      ['"\\xF0"', 0360.chr.force_encoding('utf-8')],
+      ['"\\xF1"', 0361.chr.force_encoding('utf-8')],
+      ['"\\xF2"', 0362.chr.force_encoding('utf-8')],
+      ['"\\xF3"', 0363.chr.force_encoding('utf-8')],
+      ['"\\xF4"', 0364.chr.force_encoding('utf-8')],
+      ['"\\xF5"', 0365.chr.force_encoding('utf-8')],
+      ['"\\xF6"', 0366.chr.force_encoding('utf-8')],
+      ['"\\xF7"', 0367.chr.force_encoding('utf-8')],
+      ['"\\xF8"', 0370.chr.force_encoding('utf-8')],
+      ['"\\xF9"', 0371.chr.force_encoding('utf-8')],
+      ['"\\xFA"', 0372.chr.force_encoding('utf-8')],
+      ['"\\xFB"', 0373.chr.force_encoding('utf-8')],
+      ['"\\xFC"', 0374.chr.force_encoding('utf-8')],
+      ['"\\xFD"', 0375.chr.force_encoding('utf-8')],
+      ['"\\xFE"', 0376.chr.force_encoding('utf-8')],
+      ['"\\xFF"', 0377.chr.force_encoding('utf-8')]
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with lower-case alpha characters unescaped" do
-      [ ['"a"', 'a'],
-        ['"b"', 'b'],
-        ['"c"', 'c'],
-        ['"d"', 'd'],
-        ['"e"', 'e'],
-        ['"f"', 'f'],
-        ['"g"', 'g'],
-        ['"h"', 'h'],
-        ['"i"', 'i'],
-        ['"j"', 'j'],
-        ['"k"', 'k'],
-        ['"l"', 'l'],
-        ['"m"', 'm'],
-        ['"n"', 'n'],
-        ['"o"', 'o'],
-        ['"p"', 'p'],
-        ['"q"', 'q'],
-        ['"r"', 'r'],
-        ['"s"', 's'],
-        ['"t"', 't'],
-        ['"u"', 'u'],
-        ['"v"', 'v'],
-        ['"w"', 'w'],
-        ['"x"', 'x'],
-        ['"y"', 'y'],
-        ['"z"', 'z']
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with \\u{} notation replaced with multi-byte UTF-8 characters" do
+    [ ['"\u{80}"', 0200.chr('utf-8')],
+      ['"\u{81}"', 0201.chr('utf-8')],
+      ['"\u{82}"', 0202.chr('utf-8')],
+      ['"\u{83}"', 0203.chr('utf-8')],
+      ['"\u{84}"', 0204.chr('utf-8')],
+      ['"\u{86}"', 0206.chr('utf-8')],
+      ['"\u{87}"', 0207.chr('utf-8')],
+      ['"\u{88}"', 0210.chr('utf-8')],
+      ['"\u{89}"', 0211.chr('utf-8')],
+      ['"\u{8a}"', 0212.chr('utf-8')],
+      ['"\u{8b}"', 0213.chr('utf-8')],
+      ['"\u{8c}"', 0214.chr('utf-8')],
+      ['"\u{8d}"', 0215.chr('utf-8')],
+      ['"\u{8e}"', 0216.chr('utf-8')],
+      ['"\u{8f}"', 0217.chr('utf-8')],
+      ['"\u{90}"', 0220.chr('utf-8')],
+      ['"\u{91}"', 0221.chr('utf-8')],
+      ['"\u{92}"', 0222.chr('utf-8')],
+      ['"\u{93}"', 0223.chr('utf-8')],
+      ['"\u{94}"', 0224.chr('utf-8')],
+      ['"\u{95}"', 0225.chr('utf-8')],
+      ['"\u{96}"', 0226.chr('utf-8')],
+      ['"\u{97}"', 0227.chr('utf-8')],
+      ['"\u{98}"', 0230.chr('utf-8')],
+      ['"\u{99}"', 0231.chr('utf-8')],
+      ['"\u{9a}"', 0232.chr('utf-8')],
+      ['"\u{9b}"', 0233.chr('utf-8')],
+      ['"\u{9c}"', 0234.chr('utf-8')],
+      ['"\u{9d}"', 0235.chr('utf-8')],
+      ['"\u{9e}"', 0236.chr('utf-8')],
+      ['"\u{9f}"', 0237.chr('utf-8')],
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with \\x notation replaced with non-printing ASCII character" do
-      [ ['"\\x00"', 0000.chr.force_encoding('utf-8')],
-        ['"\\x01"', 0001.chr.force_encoding('utf-8')],
-        ['"\\x02"', 0002.chr.force_encoding('utf-8')],
-        ['"\\x03"', 0003.chr.force_encoding('utf-8')],
-        ['"\\x04"', 0004.chr.force_encoding('utf-8')],
-        ['"\\x05"', 0005.chr.force_encoding('utf-8')],
-        ['"\\x06"', 0006.chr.force_encoding('utf-8')],
-        ['"\\x0E"', 0016.chr.force_encoding('utf-8')],
-        ['"\\x0F"', 0017.chr.force_encoding('utf-8')],
-        ['"\\x10"', 0020.chr.force_encoding('utf-8')],
-        ['"\\x11"', 0021.chr.force_encoding('utf-8')],
-        ['"\\x12"', 0022.chr.force_encoding('utf-8')],
-        ['"\\x13"', 0023.chr.force_encoding('utf-8')],
-        ['"\\x14"', 0024.chr.force_encoding('utf-8')],
-        ['"\\x15"', 0025.chr.force_encoding('utf-8')],
-        ['"\\x16"', 0026.chr.force_encoding('utf-8')],
-        ['"\\x17"', 0027.chr.force_encoding('utf-8')],
-        ['"\\x18"', 0030.chr.force_encoding('utf-8')],
-        ['"\\x19"', 0031.chr.force_encoding('utf-8')],
-        ['"\\x1A"', 0032.chr.force_encoding('utf-8')],
-        ['"\\x1C"', 0034.chr.force_encoding('utf-8')],
-        ['"\\x1D"', 0035.chr.force_encoding('utf-8')],
-        ['"\\x1E"', 0036.chr.force_encoding('utf-8')],
-        ['"\\x1F"', 0037.chr.force_encoding('utf-8')],
-        ['"\\x7F"', 0177.chr.force_encoding('utf-8')],
-        ['"\\x80"', 0200.chr.force_encoding('utf-8')],
-        ['"\\x81"', 0201.chr.force_encoding('utf-8')],
-        ['"\\x82"', 0202.chr.force_encoding('utf-8')],
-        ['"\\x83"', 0203.chr.force_encoding('utf-8')],
-        ['"\\x84"', 0204.chr.force_encoding('utf-8')],
-        ['"\\x85"', 0205.chr.force_encoding('utf-8')],
-        ['"\\x86"', 0206.chr.force_encoding('utf-8')],
-        ['"\\x87"', 0207.chr.force_encoding('utf-8')],
-        ['"\\x88"', 0210.chr.force_encoding('utf-8')],
-        ['"\\x89"', 0211.chr.force_encoding('utf-8')],
-        ['"\\x8A"', 0212.chr.force_encoding('utf-8')],
-        ['"\\x8B"', 0213.chr.force_encoding('utf-8')],
-        ['"\\x8C"', 0214.chr.force_encoding('utf-8')],
-        ['"\\x8D"', 0215.chr.force_encoding('utf-8')],
-        ['"\\x8E"', 0216.chr.force_encoding('utf-8')],
-        ['"\\x8F"', 0217.chr.force_encoding('utf-8')],
-        ['"\\x90"', 0220.chr.force_encoding('utf-8')],
-        ['"\\x91"', 0221.chr.force_encoding('utf-8')],
-        ['"\\x92"', 0222.chr.force_encoding('utf-8')],
-        ['"\\x93"', 0223.chr.force_encoding('utf-8')],
-        ['"\\x94"', 0224.chr.force_encoding('utf-8')],
-        ['"\\x95"', 0225.chr.force_encoding('utf-8')],
-        ['"\\x96"', 0226.chr.force_encoding('utf-8')],
-        ['"\\x97"', 0227.chr.force_encoding('utf-8')],
-        ['"\\x98"', 0230.chr.force_encoding('utf-8')],
-        ['"\\x99"', 0231.chr.force_encoding('utf-8')],
-        ['"\\x9A"', 0232.chr.force_encoding('utf-8')],
-        ['"\\x9B"', 0233.chr.force_encoding('utf-8')],
-        ['"\\x9C"', 0234.chr.force_encoding('utf-8')],
-        ['"\\x9D"', 0235.chr.force_encoding('utf-8')],
-        ['"\\x9E"', 0236.chr.force_encoding('utf-8')],
-        ['"\\x9F"', 0237.chr.force_encoding('utf-8')],
-        ['"\\xA0"', 0240.chr.force_encoding('utf-8')],
-        ['"\\xA1"', 0241.chr.force_encoding('utf-8')],
-        ['"\\xA2"', 0242.chr.force_encoding('utf-8')],
-        ['"\\xA3"', 0243.chr.force_encoding('utf-8')],
-        ['"\\xA4"', 0244.chr.force_encoding('utf-8')],
-        ['"\\xA5"', 0245.chr.force_encoding('utf-8')],
-        ['"\\xA6"', 0246.chr.force_encoding('utf-8')],
-        ['"\\xA7"', 0247.chr.force_encoding('utf-8')],
-        ['"\\xA8"', 0250.chr.force_encoding('utf-8')],
-        ['"\\xA9"', 0251.chr.force_encoding('utf-8')],
-        ['"\\xAA"', 0252.chr.force_encoding('utf-8')],
-        ['"\\xAB"', 0253.chr.force_encoding('utf-8')],
-        ['"\\xAC"', 0254.chr.force_encoding('utf-8')],
-        ['"\\xAD"', 0255.chr.force_encoding('utf-8')],
-        ['"\\xAE"', 0256.chr.force_encoding('utf-8')],
-        ['"\\xAF"', 0257.chr.force_encoding('utf-8')],
-        ['"\\xB0"', 0260.chr.force_encoding('utf-8')],
-        ['"\\xB1"', 0261.chr.force_encoding('utf-8')],
-        ['"\\xB2"', 0262.chr.force_encoding('utf-8')],
-        ['"\\xB3"', 0263.chr.force_encoding('utf-8')],
-        ['"\\xB4"', 0264.chr.force_encoding('utf-8')],
-        ['"\\xB5"', 0265.chr.force_encoding('utf-8')],
-        ['"\\xB6"', 0266.chr.force_encoding('utf-8')],
-        ['"\\xB7"', 0267.chr.force_encoding('utf-8')],
-        ['"\\xB8"', 0270.chr.force_encoding('utf-8')],
-        ['"\\xB9"', 0271.chr.force_encoding('utf-8')],
-        ['"\\xBA"', 0272.chr.force_encoding('utf-8')],
-        ['"\\xBB"', 0273.chr.force_encoding('utf-8')],
-        ['"\\xBC"', 0274.chr.force_encoding('utf-8')],
-        ['"\\xBD"', 0275.chr.force_encoding('utf-8')],
-        ['"\\xBE"', 0276.chr.force_encoding('utf-8')],
-        ['"\\xBF"', 0277.chr.force_encoding('utf-8')],
-        ['"\\xC0"', 0300.chr.force_encoding('utf-8')],
-        ['"\\xC1"', 0301.chr.force_encoding('utf-8')],
-        ['"\\xC2"', 0302.chr.force_encoding('utf-8')],
-        ['"\\xC3"', 0303.chr.force_encoding('utf-8')],
-        ['"\\xC4"', 0304.chr.force_encoding('utf-8')],
-        ['"\\xC5"', 0305.chr.force_encoding('utf-8')],
-        ['"\\xC6"', 0306.chr.force_encoding('utf-8')],
-        ['"\\xC7"', 0307.chr.force_encoding('utf-8')],
-        ['"\\xC8"', 0310.chr.force_encoding('utf-8')],
-        ['"\\xC9"', 0311.chr.force_encoding('utf-8')],
-        ['"\\xCA"', 0312.chr.force_encoding('utf-8')],
-        ['"\\xCB"', 0313.chr.force_encoding('utf-8')],
-        ['"\\xCC"', 0314.chr.force_encoding('utf-8')],
-        ['"\\xCD"', 0315.chr.force_encoding('utf-8')],
-        ['"\\xCE"', 0316.chr.force_encoding('utf-8')],
-        ['"\\xCF"', 0317.chr.force_encoding('utf-8')],
-        ['"\\xD0"', 0320.chr.force_encoding('utf-8')],
-        ['"\\xD1"', 0321.chr.force_encoding('utf-8')],
-        ['"\\xD2"', 0322.chr.force_encoding('utf-8')],
-        ['"\\xD3"', 0323.chr.force_encoding('utf-8')],
-        ['"\\xD4"', 0324.chr.force_encoding('utf-8')],
-        ['"\\xD5"', 0325.chr.force_encoding('utf-8')],
-        ['"\\xD6"', 0326.chr.force_encoding('utf-8')],
-        ['"\\xD7"', 0327.chr.force_encoding('utf-8')],
-        ['"\\xD8"', 0330.chr.force_encoding('utf-8')],
-        ['"\\xD9"', 0331.chr.force_encoding('utf-8')],
-        ['"\\xDA"', 0332.chr.force_encoding('utf-8')],
-        ['"\\xDB"', 0333.chr.force_encoding('utf-8')],
-        ['"\\xDC"', 0334.chr.force_encoding('utf-8')],
-        ['"\\xDD"', 0335.chr.force_encoding('utf-8')],
-        ['"\\xDE"', 0336.chr.force_encoding('utf-8')],
-        ['"\\xDF"', 0337.chr.force_encoding('utf-8')],
-        ['"\\xE0"', 0340.chr.force_encoding('utf-8')],
-        ['"\\xE1"', 0341.chr.force_encoding('utf-8')],
-        ['"\\xE2"', 0342.chr.force_encoding('utf-8')],
-        ['"\\xE3"', 0343.chr.force_encoding('utf-8')],
-        ['"\\xE4"', 0344.chr.force_encoding('utf-8')],
-        ['"\\xE5"', 0345.chr.force_encoding('utf-8')],
-        ['"\\xE6"', 0346.chr.force_encoding('utf-8')],
-        ['"\\xE7"', 0347.chr.force_encoding('utf-8')],
-        ['"\\xE8"', 0350.chr.force_encoding('utf-8')],
-        ['"\\xE9"', 0351.chr.force_encoding('utf-8')],
-        ['"\\xEA"', 0352.chr.force_encoding('utf-8')],
-        ['"\\xEB"', 0353.chr.force_encoding('utf-8')],
-        ['"\\xEC"', 0354.chr.force_encoding('utf-8')],
-        ['"\\xED"', 0355.chr.force_encoding('utf-8')],
-        ['"\\xEE"', 0356.chr.force_encoding('utf-8')],
-        ['"\\xEF"', 0357.chr.force_encoding('utf-8')],
-        ['"\\xF0"', 0360.chr.force_encoding('utf-8')],
-        ['"\\xF1"', 0361.chr.force_encoding('utf-8')],
-        ['"\\xF2"', 0362.chr.force_encoding('utf-8')],
-        ['"\\xF3"', 0363.chr.force_encoding('utf-8')],
-        ['"\\xF4"', 0364.chr.force_encoding('utf-8')],
-        ['"\\xF5"', 0365.chr.force_encoding('utf-8')],
-        ['"\\xF6"', 0366.chr.force_encoding('utf-8')],
-        ['"\\xF7"', 0367.chr.force_encoding('utf-8')],
-        ['"\\xF8"', 0370.chr.force_encoding('utf-8')],
-        ['"\\xF9"', 0371.chr.force_encoding('utf-8')],
-        ['"\\xFA"', 0372.chr.force_encoding('utf-8')],
-        ['"\\xFB"', 0373.chr.force_encoding('utf-8')],
-        ['"\\xFC"', 0374.chr.force_encoding('utf-8')],
-        ['"\\xFD"', 0375.chr.force_encoding('utf-8')],
-        ['"\\xFE"', 0376.chr.force_encoding('utf-8')],
-        ['"\\xFF"', 0377.chr.force_encoding('utf-8')]
-      ].should be_computed_by(:undump)
-    end
+  it "returns a string with \\uXXXX notation replaced with multi-byte UTF-8 characters" do
+    [ ['"\u0080"', 0200.chr('utf-8')],
+      ['"\u0081"', 0201.chr('utf-8')],
+      ['"\u0082"', 0202.chr('utf-8')],
+      ['"\u0083"', 0203.chr('utf-8')],
+      ['"\u0084"', 0204.chr('utf-8')],
+      ['"\u0086"', 0206.chr('utf-8')],
+      ['"\u0087"', 0207.chr('utf-8')],
+      ['"\u0088"', 0210.chr('utf-8')],
+      ['"\u0089"', 0211.chr('utf-8')],
+      ['"\u008a"', 0212.chr('utf-8')],
+      ['"\u008b"', 0213.chr('utf-8')],
+      ['"\u008c"', 0214.chr('utf-8')],
+      ['"\u008d"', 0215.chr('utf-8')],
+      ['"\u008e"', 0216.chr('utf-8')],
+      ['"\u008f"', 0217.chr('utf-8')],
+      ['"\u0090"', 0220.chr('utf-8')],
+      ['"\u0091"', 0221.chr('utf-8')],
+      ['"\u0092"', 0222.chr('utf-8')],
+      ['"\u0093"', 0223.chr('utf-8')],
+      ['"\u0094"', 0224.chr('utf-8')],
+      ['"\u0095"', 0225.chr('utf-8')],
+      ['"\u0096"', 0226.chr('utf-8')],
+      ['"\u0097"', 0227.chr('utf-8')],
+      ['"\u0098"', 0230.chr('utf-8')],
+      ['"\u0099"', 0231.chr('utf-8')],
+      ['"\u009a"', 0232.chr('utf-8')],
+      ['"\u009b"', 0233.chr('utf-8')],
+      ['"\u009c"', 0234.chr('utf-8')],
+      ['"\u009d"', 0235.chr('utf-8')],
+      ['"\u009e"', 0236.chr('utf-8')],
+      ['"\u009f"', 0237.chr('utf-8')],
+    ].should be_computed_by(:undump)
+  end
 
-    it "returns a string with \\u{} notation replaced with multi-byte UTF-8 characters" do
-      [ ['"\u{80}"', 0200.chr('utf-8')],
-        ['"\u{81}"', 0201.chr('utf-8')],
-        ['"\u{82}"', 0202.chr('utf-8')],
-        ['"\u{83}"', 0203.chr('utf-8')],
-        ['"\u{84}"', 0204.chr('utf-8')],
-        ['"\u{86}"', 0206.chr('utf-8')],
-        ['"\u{87}"', 0207.chr('utf-8')],
-        ['"\u{88}"', 0210.chr('utf-8')],
-        ['"\u{89}"', 0211.chr('utf-8')],
-        ['"\u{8a}"', 0212.chr('utf-8')],
-        ['"\u{8b}"', 0213.chr('utf-8')],
-        ['"\u{8c}"', 0214.chr('utf-8')],
-        ['"\u{8d}"', 0215.chr('utf-8')],
-        ['"\u{8e}"', 0216.chr('utf-8')],
-        ['"\u{8f}"', 0217.chr('utf-8')],
-        ['"\u{90}"', 0220.chr('utf-8')],
-        ['"\u{91}"', 0221.chr('utf-8')],
-        ['"\u{92}"', 0222.chr('utf-8')],
-        ['"\u{93}"', 0223.chr('utf-8')],
-        ['"\u{94}"', 0224.chr('utf-8')],
-        ['"\u{95}"', 0225.chr('utf-8')],
-        ['"\u{96}"', 0226.chr('utf-8')],
-        ['"\u{97}"', 0227.chr('utf-8')],
-        ['"\u{98}"', 0230.chr('utf-8')],
-        ['"\u{99}"', 0231.chr('utf-8')],
-        ['"\u{9a}"', 0232.chr('utf-8')],
-        ['"\u{9b}"', 0233.chr('utf-8')],
-        ['"\u{9c}"', 0234.chr('utf-8')],
-        ['"\u{9d}"', 0235.chr('utf-8')],
-        ['"\u{9e}"', 0236.chr('utf-8')],
-        ['"\u{9f}"', 0237.chr('utf-8')],
-      ].should be_computed_by(:undump)
-    end
+  it "undumps correctly string produced from non ASCII-compatible one" do
+    s = "\u{876}".encode('utf-16be')
+    s.dump.undump.should == s
 
-    it "returns a string with \\uXXXX notation replaced with multi-byte UTF-8 characters" do
-      [ ['"\u0080"', 0200.chr('utf-8')],
-        ['"\u0081"', 0201.chr('utf-8')],
-        ['"\u0082"', 0202.chr('utf-8')],
-        ['"\u0083"', 0203.chr('utf-8')],
-        ['"\u0084"', 0204.chr('utf-8')],
-        ['"\u0086"', 0206.chr('utf-8')],
-        ['"\u0087"', 0207.chr('utf-8')],
-        ['"\u0088"', 0210.chr('utf-8')],
-        ['"\u0089"', 0211.chr('utf-8')],
-        ['"\u008a"', 0212.chr('utf-8')],
-        ['"\u008b"', 0213.chr('utf-8')],
-        ['"\u008c"', 0214.chr('utf-8')],
-        ['"\u008d"', 0215.chr('utf-8')],
-        ['"\u008e"', 0216.chr('utf-8')],
-        ['"\u008f"', 0217.chr('utf-8')],
-        ['"\u0090"', 0220.chr('utf-8')],
-        ['"\u0091"', 0221.chr('utf-8')],
-        ['"\u0092"', 0222.chr('utf-8')],
-        ['"\u0093"', 0223.chr('utf-8')],
-        ['"\u0094"', 0224.chr('utf-8')],
-        ['"\u0095"', 0225.chr('utf-8')],
-        ['"\u0096"', 0226.chr('utf-8')],
-        ['"\u0097"', 0227.chr('utf-8')],
-        ['"\u0098"', 0230.chr('utf-8')],
-        ['"\u0099"', 0231.chr('utf-8')],
-        ['"\u009a"', 0232.chr('utf-8')],
-        ['"\u009b"', 0233.chr('utf-8')],
-        ['"\u009c"', 0234.chr('utf-8')],
-        ['"\u009d"', 0235.chr('utf-8')],
-        ['"\u009e"', 0236.chr('utf-8')],
-        ['"\u009f"', 0237.chr('utf-8')],
-      ].should be_computed_by(:undump)
-    end
+    '"\\bv".force_encoding("UTF-16BE")'.undump.should == "\u0876".encode('utf-16be')
+  end
 
-    it "undumps correctly string produced from non ASCII-compatible one" do
-      s = "\u{876}".encode('utf-16be')
-      s.dump.undump.should == s
+  it "returns a String in the same encoding as self" do
+    '"foo"'.encode("ISO-8859-1").undump.encoding.should == Encoding::ISO_8859_1
+    '"foo"'.encode('windows-1251').undump.encoding.should == Encoding::Windows_1251
+  end
 
-      '"\\bv".force_encoding("UTF-16BE")'.undump.should == "\u0876".encode('utf-16be')
+  describe "Limitations" do
+    it "cannot undump non ASCII-compatible string" do
+      -> { '"foo"'.encode('utf-16le').undump }.should.raise(Encoding::CompatibilityError)
     end
+  end
 
-    it "keeps origin encoding" do
-      '"foo"'.encode("ISO-8859-1").undump.encoding.should == Encoding::ISO_8859_1
-      '"foo"'.encode('windows-1251').undump.encoding.should == Encoding::Windows_1251
+  describe "invalid dump" do
+    it "raises RuntimeError exception if wrapping \" are missing" do
+      -> { 'foo'.undump }.should.raise(RuntimeError, /invalid dumped string/)
+      -> { '"foo'.undump }.should.raise(RuntimeError, /unterminated dumped string/)
+      -> { 'foo"'.undump }.should.raise(RuntimeError, /invalid dumped string/)
+      -> { "'foo'".undump }.should.raise(RuntimeError, /invalid dumped string/)
     end
 
-    describe "Limitations" do
-      it "cannot undump non ASCII-compatible string" do
-        -> { '"foo"'.encode('utf-16le').undump }.should raise_error(Encoding::CompatibilityError)
-      end
+    it "raises RuntimeError if there is incorrect \\x sequence" do
+      -> { '"\x"'.undump }.should.raise(RuntimeError, /invalid hex escape/)
+      -> { '"\\x3y"'.undump }.should.raise(RuntimeError, /invalid hex escape/)
     end
 
-    describe "invalid dump" do
-      it "raises RuntimeError exception if wrapping \" are missing" do
-        -> { 'foo'.undump }.should raise_error(RuntimeError, /invalid dumped string/)
-        -> { '"foo'.undump }.should raise_error(RuntimeError, /unterminated dumped string/)
-        -> { 'foo"'.undump }.should raise_error(RuntimeError, /invalid dumped string/)
-        -> { "'foo'".undump }.should raise_error(RuntimeError, /invalid dumped string/)
-      end
-
-      it "raises RuntimeError if there is incorrect \\x sequence" do
-        -> { '"\x"'.undump }.should raise_error(RuntimeError, /invalid hex escape/)
-        -> { '"\\x3y"'.undump }.should raise_error(RuntimeError, /invalid hex escape/)
-      end
-
-      it "raises RuntimeError in there is incorrect \\u sequence" do
-        -> { '"\\u"'.undump }.should raise_error(RuntimeError, /invalid Unicode escape/)
-        -> { '"\\u{"'.undump }.should raise_error(RuntimeError, /invalid Unicode escape/)
-        -> { '"\\u{3042"'.undump }.should raise_error(RuntimeError, /invalid Unicode escape/)
-        -> { '"\\u"'.undump }.should raise_error(RuntimeError, /invalid Unicode escape/)
-      end
+    it "raises RuntimeError in there is incorrect \\u sequence" do
+      -> { '"\\u"'.undump }.should.raise(RuntimeError, /invalid Unicode escape/)
+      -> { '"\\u{"'.undump }.should.raise(RuntimeError, /invalid Unicode escape/)
+      -> { '"\\u{3042"'.undump }.should.raise(RuntimeError, /invalid Unicode escape/)
+      -> { '"\\u"'.undump }.should.raise(RuntimeError, /invalid Unicode escape/)
+    end
 
-      it "raises RuntimeError if there is malformed dump of non ASCII-compatible string" do
-        -> { '"".force_encoding("BINARY"'.undump }.should raise_error(RuntimeError, /invalid dumped string/)
-        -> { '"".force_encoding("Unknown")'.undump }.should raise_error(RuntimeError, /dumped string has unknown encoding name/)
-        -> { '"".force_encoding()'.undump }.should raise_error(RuntimeError, /invalid dumped string/)
-      end
+    it "raises RuntimeError if there is malformed dump of non ASCII-compatible string" do
+      -> { '"".force_encoding("BINARY"'.undump }.should.raise(RuntimeError, /invalid dumped string/)
+      -> { '"".force_encoding("Unknown")'.undump }.should.raise(RuntimeError, /dumped string has unknown encoding name/)
+      -> { '"".force_encoding()'.undump }.should.raise(RuntimeError, /invalid dumped string/)
+    end
 
-      it "raises RuntimeError if string contains \0 character" do
-        -> { "\"foo\0\"".undump }.should raise_error(RuntimeError, /string contains null byte/)
-      end
+    it "raises RuntimeError if string contains \0 character" do
+      -> { "\"foo\0\"".undump }.should.raise(RuntimeError, /string contains null byte/)
+    end
 
-      it "raises RuntimeError if string contains non ASCII character" do
-        -> { "\"\u3042\"".undump }.should raise_error(RuntimeError, /non-ASCII character detected/)
-      end
+    it "raises RuntimeError if string contains non ASCII character" do
+      -> { "\"\u3042\"".undump }.should.raise(RuntimeError, /non-ASCII character detected/)
+    end
 
-      it "raises RuntimeError if there are some excessive \"" do
-        -> { '" "" "'.undump }.should raise_error(RuntimeError, /invalid dumped string/)
-      end
+    it "raises RuntimeError if there are some excessive \"" do
+      -> { '" "" "'.undump }.should.raise(RuntimeError, /invalid dumped string/)
     end
   end
 end
diff --git a/spec/ruby/core/string/unicode_normalize_spec.rb b/spec/ruby/core/string/unicode_normalize_spec.rb
index 6de7533fc7..92b3a46b43 100644
--- a/spec/ruby/core/string/unicode_normalize_spec.rb
+++ b/spec/ruby/core/string/unicode_normalize_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 # Examples taken from http://www.unicode.org/reports/tr15/#Norm_Forms
@@ -50,13 +51,13 @@ describe "String#unicode_normalize" do
   it "raises an Encoding::CompatibilityError if string is not in an unicode encoding" do
     -> do
       [0xE0].pack('C').force_encoding("ISO-8859-1").unicode_normalize(:nfd)
-    end.should raise_error(Encoding::CompatibilityError)
+    end.should.raise(Encoding::CompatibilityError)
   end
 
   it "raises an ArgumentError if the specified form is invalid" do
     -> {
       @angstrom.unicode_normalize(:invalid_form)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
 
@@ -103,13 +104,13 @@ describe "String#unicode_normalize!" do
   it "raises an Encoding::CompatibilityError if the string is not in an unicode encoding" do
     -> {
       [0xE0].pack('C').force_encoding("ISO-8859-1").unicode_normalize!
-    }.should raise_error(Encoding::CompatibilityError)
+    }.should.raise(Encoding::CompatibilityError)
   end
 
   it "raises an ArgumentError if the specified form is invalid" do
     ohm = "\u2126"
     -> {
       ohm.unicode_normalize!(:invalid_form)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/unicode_normalized_spec.rb b/spec/ruby/core/string/unicode_normalized_spec.rb
index 25c810a98f..3ca27d35dd 100644
--- a/spec/ruby/core/string/unicode_normalized_spec.rb
+++ b/spec/ruby/core/string/unicode_normalized_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe "String#unicode_normalized?" do
@@ -24,51 +25,51 @@ describe "String#unicode_normalized?" do
   end
 
   it "defaults to the nfc normalization form if no forms are specified" do
-    @nfc_normalized_str.unicode_normalized?.should == true
-    @nfd_normalized_str.unicode_normalized?.should == false
+    @nfc_normalized_str.should.unicode_normalized?
+    @nfd_normalized_str.should_not.unicode_normalized?
   end
 
   it "returns true if string is empty" do
-    "".unicode_normalized?.should == true
+    "".should.unicode_normalized?
   end
 
   it "returns true if string does not contain any unicode codepoints" do
-    "abc".unicode_normalized?.should == true
+    "abc".should.unicode_normalized?
   end
 
   it "raises an Encoding::CompatibilityError if the string is not in an unicode encoding" do
-    -> { @nfc_normalized_str.force_encoding("ISO-8859-1").unicode_normalized? }.should raise_error(Encoding::CompatibilityError)
+    -> { @nfc_normalized_str.force_encoding("ISO-8859-1").unicode_normalized? }.should.raise(Encoding::CompatibilityError)
   end
 
   it "raises an ArgumentError if the specified form is invalid" do
-    -> { @nfc_normalized_str.unicode_normalized?(:invalid_form) }.should raise_error(ArgumentError)
+    -> { @nfc_normalized_str.unicode_normalized?(:invalid_form) }.should.raise(ArgumentError)
   end
 
   it "returns true if str is in Unicode normalization form (nfc)" do
     str = "a\u0300"
-    str.unicode_normalized?(:nfc).should be_false
+    str.unicode_normalized?(:nfc).should == false
     str.unicode_normalize!(:nfc)
-    str.unicode_normalized?(:nfc).should be_true
+    str.unicode_normalized?(:nfc).should == true
   end
 
   it "returns true if str is in Unicode normalization form (nfd)" do
     str = "a\u00E0"
-    str.unicode_normalized?(:nfd).should be_false
+    str.unicode_normalized?(:nfd).should == false
     str.unicode_normalize!(:nfd)
-    str.unicode_normalized?(:nfd).should be_true
+    str.unicode_normalized?(:nfd).should == true
   end
 
   it "returns true if str is in Unicode normalization form (nfkc)" do
     str = "a\u0300"
-    str.unicode_normalized?(:nfkc).should be_false
+    str.unicode_normalized?(:nfkc).should == false
     str.unicode_normalize!(:nfkc)
-    str.unicode_normalized?(:nfkc).should be_true
+    str.unicode_normalized?(:nfkc).should == true
   end
 
   it "returns true if str is in Unicode normalization form (nfkd)" do
     str = "a\u00E0"
-    str.unicode_normalized?(:nfkd).should be_false
+    str.unicode_normalized?(:nfkd).should == false
     str.unicode_normalize!(:nfkd)
-    str.unicode_normalized?(:nfkd).should be_true
+    str.unicode_normalized?(:nfkd).should == true
   end
 end
diff --git a/spec/ruby/core/string/unpack/a_spec.rb b/spec/ruby/core/string/unpack/a_spec.rb
index 2d83b4c824..a68e842e15 100644
--- a/spec/ruby/core/string/unpack/a_spec.rb
+++ b/spec/ruby/core/string/unpack/a_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -31,7 +31,7 @@ describe "String#unpack with format 'A'" do
   end
 
   it "decodes into raw (ascii) string values" do
-    str = "str".force_encoding('UTF-8').unpack("A*")[0]
+    str = "str".dup.force_encoding('UTF-8').unpack("A*")[0]
     str.encoding.should == Encoding::BINARY
   end
 
diff --git a/spec/ruby/core/string/unpack/at_spec.rb b/spec/ruby/core/string/unpack/at_spec.rb
index 70b2389d69..f4999f5922 100644
--- a/spec/ruby/core/string/unpack/at_spec.rb
+++ b/spec/ruby/core/string/unpack/at_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -24,6 +24,6 @@ describe "String#unpack with format '@'" do
   end
 
   it "raises an ArgumentError if the count exceeds the size of the String" do
-    -> { "\x01\x02\x03\x04".unpack("C2@5C") }.should raise_error(ArgumentError)
+    -> { "\x01\x02\x03\x04".unpack("C2@5C") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/unpack/b_spec.rb b/spec/ruby/core/string/unpack/b_spec.rb
index 1a838d6c7c..fac6ef5151 100644
--- a/spec/ruby/core/string/unpack/b_spec.rb
+++ b/spec/ruby/core/string/unpack/b_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -86,13 +86,20 @@ describe "String#unpack with format 'B'" do
     ].should be_computed_by(:unpack, "BBB")
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x80\x00".unpack("B\x00B").should == ["1", "0"]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x80\x00".unpack("B\x00B")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
     "\x80\x00".unpack("B B").should == ["1", "0"]
   end
+
+  it "decodes into US-ASCII string values" do
+    str = "s".dup.force_encoding('UTF-8').unpack("B*")[0]
+    str.encoding.name.should == 'US-ASCII'
+  end
 end
 
 describe "String#unpack with format 'b'" do
@@ -177,8 +184,10 @@ describe "String#unpack with format 'b'" do
     ].should be_computed_by(:unpack, "bbb")
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x01\x00".unpack("b\x00b").should == ["1", "0"]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x01\x00".unpack("b\x00b")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -186,8 +195,7 @@ describe "String#unpack with format 'b'" do
   end
 
   it "decodes into US-ASCII string values" do
-    str = "s".force_encoding('UTF-8').unpack("b*")[0]
+    str = "s".dup.force_encoding('UTF-8').unpack("b*")[0]
     str.encoding.name.should == 'US-ASCII'
   end
-
 end
diff --git a/spec/ruby/core/string/unpack/c_spec.rb b/spec/ruby/core/string/unpack/c_spec.rb
index ed8caa4895..d881015b5e 100644
--- a/spec/ruby/core/string/unpack/c_spec.rb
+++ b/spec/ruby/core/string/unpack/c_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -35,8 +35,10 @@ describe :string_unpack_8bit, shared: true do
     ].should be_computed_by(:unpack, unpack_format(3))
   end
 
-  it "ignores NULL bytes between directives" do
-    "abc".unpack(unpack_format("\000", 2)).should == [97, 98]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "abc".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/string/unpack/carret_spec.rb b/spec/ruby/core/string/unpack/carret_spec.rb
new file mode 100644
index 0000000000..815df0c718
--- /dev/null
+++ b/spec/ruby/core/string/unpack/carret_spec.rb
@@ -0,0 +1,43 @@
+# encoding: binary
+ruby_version_is "4.1" do
+  require_relative '../../../spec_helper'
+  require_relative '../fixtures/classes'
+  require_relative 'shared/basic'
+
+  describe "String#unpack with format '^'" do
+    it_behaves_like :string_unpack_basic, '^'
+    it_behaves_like :string_unpack_no_platform, '^'
+
+    it "returns the current offset that start from 0" do
+      "".unpack("^").should == [0]
+    end
+
+    it "returns the current offset after the last decode ended" do
+      "a".unpack("CC^").should == [97, nil, 1]
+    end
+
+    it "returns the current offset that start from the given offset" do
+      "abc".unpack("^", offset: 1).should == [1]
+    end
+
+    it "returns the offset moved by 'X'" do
+      "\x01\x02\x03\x04".unpack("C3X2^").should == [1, 2, 3, 1]
+    end
+
+    it "returns the offset moved by 'x'" do
+      "\x01\x02\x03\x04".unpack("Cx2^").should == [1, 3]
+    end
+
+    it "returns the offset to the position the previous decode ended" do
+      "foo".unpack("A4^").should == ["foo", 3]
+      "foo".unpack("a4^").should == ["foo", 3]
+      "foo".unpack("Z5^").should == ["foo", 3]
+    end
+
+    it "returns the offset including truncated part" do
+      "foo   ".unpack("A*^").should == ["foo", 6]
+      "foo\0".unpack("Z*^").should == ["foo", 4]
+      "foo\0\0\0".unpack("Z5^").should == ["foo", 5]
+    end
+  end
+end
diff --git a/spec/ruby/core/string/unpack/comment_spec.rb b/spec/ruby/core/string/unpack/comment_spec.rb
index e18a53df3c..050d2b7fc0 100644
--- a/spec/ruby/core/string/unpack/comment_spec.rb
+++ b/spec/ruby/core/string/unpack/comment_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
diff --git a/spec/ruby/core/string/unpack/h_spec.rb b/spec/ruby/core/string/unpack/h_spec.rb
index f2f5dcf396..0cf8d943a7 100644
--- a/spec/ruby/core/string/unpack/h_spec.rb
+++ b/spec/ruby/core/string/unpack/h_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -56,8 +56,10 @@ describe "String#unpack with format 'H'" do
     ].should be_computed_by(:unpack, "HHH")
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x01\x10".unpack("H\x00H").should == ["0", "1"]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x01\x10".unpack("H\x00H")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -121,8 +123,10 @@ describe "String#unpack with format 'h'" do
     ].should be_computed_by(:unpack, "hhh")
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x01\x10".unpack("h\x00h").should == ["1", "0"]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x01\x10".unpack("h\x00h")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/string/unpack/l_spec.rb b/spec/ruby/core/string/unpack/l_spec.rb
index 18bb68b8d0..0adb567eca 100644
--- a/spec/ruby/core/string/unpack/l_spec.rb
+++ b/spec/ruby/core/string/unpack/l_spec.rb
@@ -14,7 +14,7 @@ describe "String#unpack with format 'L'" do
     it_behaves_like :string_unpack_32bit_be_unsigned, 'L>'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :string_unpack_32bit_le, 'L<_'
       it_behaves_like :string_unpack_32bit_le, 'L_<'
@@ -44,7 +44,7 @@ describe "String#unpack with format 'L'" do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :string_unpack_64bit_le, 'L<_'
       it_behaves_like :string_unpack_64bit_le, 'L_<'
@@ -86,7 +86,7 @@ describe "String#unpack with format 'l'" do
     it_behaves_like :string_unpack_32bit_be_signed, 'l>'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :string_unpack_32bit_le, 'l<_'
       it_behaves_like :string_unpack_32bit_le, 'l_<'
@@ -116,7 +116,7 @@ describe "String#unpack with format 'l'" do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "with modifier '<' and '_'" do
       it_behaves_like :string_unpack_64bit_le, 'l<_'
       it_behaves_like :string_unpack_64bit_le, 'l_<'
@@ -160,7 +160,7 @@ little_endian do
     it_behaves_like :string_unpack_32bit_le_signed, 'l'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "String#unpack with format 'L' with modifier '_'" do
       it_behaves_like :string_unpack_32bit_le, 'L_'
       it_behaves_like :string_unpack_32bit_le_unsigned, 'L_'
@@ -182,7 +182,7 @@ little_endian do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "String#unpack with format 'L' with modifier '_'" do
       it_behaves_like :string_unpack_64bit_le, 'L_'
       it_behaves_like :string_unpack_64bit_le_unsigned, 'L_'
@@ -218,7 +218,7 @@ big_endian do
     it_behaves_like :string_unpack_32bit_be_signed, 'l'
   end
 
-  platform_is wordsize: 32 do
+  platform_is c_long_size: 32 do
     describe "String#unpack with format 'L' with modifier '_'" do
       it_behaves_like :string_unpack_32bit_be, 'L_'
       it_behaves_like :string_unpack_32bit_be_unsigned, 'L_'
@@ -240,7 +240,7 @@ big_endian do
     end
   end
 
-  platform_is wordsize: 64 do
+  platform_is c_long_size: 64 do
     describe "String#unpack with format 'L' with modifier '_'" do
       it_behaves_like :string_unpack_64bit_be, 'L_'
       it_behaves_like :string_unpack_64bit_be_unsigned, 'L_'
diff --git a/spec/ruby/core/string/unpack/m_spec.rb b/spec/ruby/core/string/unpack/m_spec.rb
index 96841f24cb..c1c1eea629 100644
--- a/spec/ruby/core/string/unpack/m_spec.rb
+++ b/spec/ruby/core/string/unpack/m_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -97,6 +97,11 @@ describe "String#unpack with format 'M'" do
       ["=FF=\n",                      ["\xff"]]
     ].should be_computed_by(:unpack, "M")
   end
+
+  it "unpacks incomplete escape sequences as literal characters" do
+    "foo=".unpack("M").should == ["foo="]
+    "foo=4".unpack("M").should == ["foo=4"]
+  end
 end
 
 describe "String#unpack with format 'm'" do
@@ -170,4 +175,18 @@ describe "String#unpack with format 'm'" do
     "".unpack("m").first.encoding.should == Encoding::BINARY
     "Ojs8PT4/QA==\n".unpack("m").first.encoding.should == Encoding::BINARY
   end
+
+  it "does not raise an error for an invalid base64 character" do
+    "dGV%zdA==".unpack("m").should == ["test"]
+  end
+
+  describe "when given count 0" do
+    it "decodes base64" do
+      "dGVzdA==".unpack("m0").should == ["test"]
+    end
+
+    it "raises an ArgumentError for an invalid base64 character" do
+      -> { "dGV%zdA==".unpack("m0") }.should.raise(ArgumentError)
+    end
+  end
 end
diff --git a/spec/ruby/core/string/unpack/p_spec.rb b/spec/ruby/core/string/unpack/p_spec.rb
index a544bc29c1..4103730269 100644
--- a/spec/ruby/core/string/unpack/p_spec.rb
+++ b/spec/ruby/core/string/unpack/p_spec.rb
@@ -15,11 +15,7 @@ describe "String#unpack with format 'P'" do
     packed = ["hello"].pack("P")
     packed.unpack("P5").should == ["hello"]
     packed.dup.unpack("P5").should == ["hello"]
-    -> { packed.to_sym.to_s.unpack("P5") }.should raise_error(ArgumentError, /no associated pointer/)
-  end
-
-  it "taints the unpacked string" do
-    ["hello"].pack("P").unpack("P5").first.tainted?.should be_true
+    -> { packed.to_sym.to_s.unpack("P5") }.should.raise(ArgumentError, /no associated pointer/)
   end
 
   it "reads as many characters as specified" do
@@ -43,10 +39,6 @@ describe "String#unpack with format 'p'" do
     packed = ["hello"].pack("p")
     packed.unpack("p").should == ["hello"]
     packed.dup.unpack("p").should == ["hello"]
-    -> { packed.to_sym.to_s.unpack("p") }.should raise_error(ArgumentError, /no associated pointer/)
-  end
-
-  it "taints the unpacked string" do
-    ["hello"].pack("p").unpack("p").first.tainted?.should be_true
+    -> { packed.to_sym.to_s.unpack("p") }.should.raise(ArgumentError, /no associated pointer/)
   end
 end
diff --git a/spec/ruby/core/string/unpack/percent_spec.rb b/spec/ruby/core/string/unpack/percent_spec.rb
index 0e27663195..7142bbf241 100644
--- a/spec/ruby/core/string/unpack/percent_spec.rb
+++ b/spec/ruby/core/string/unpack/percent_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../../spec_helper'
 
 describe "String#unpack with format '%'" do
   it "raises an Argument Error" do
-    -> { "abc".unpack("%") }.should raise_error(ArgumentError)
+    -> { "abc".unpack("%") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/unpack/r_spec.rb b/spec/ruby/core/string/unpack/r_spec.rb
new file mode 100644
index 0000000000..a385951aa8
--- /dev/null
+++ b/spec/ruby/core/string/unpack/r_spec.rb
@@ -0,0 +1,85 @@
+# encoding: binary
+require_relative '../../../spec_helper'
+require_relative '../fixtures/classes'
+require_relative 'shared/basic'
+
+ruby_version_is "4.1" do
+  describe "String#unpack with format 'R'" do
+    it_behaves_like :string_unpack_basic, 'R'
+    it_behaves_like :string_unpack_no_platform, 'R'
+
+    it "decodes a ULEB128 integer" do
+      [ ["\x00",                                     [0]],
+        ["\x01",                                     [1]],
+        ["\x7f",                                     [127]],
+        ["\x80\x01",                                 [128]],
+        ["\xff\x7f",                                 [0x3fff]],
+        ["\x80\x80\x01",                             [0x4000]],
+        ["\xff\xff\xff\xff\x0f",                     [0xffffffff]],
+        ["\x80\x80\x80\x80\x10",                     [0x100000000]],
+        ["\xff\xff\xff\xff\xff\xff\xff\xff\xff\x01", [0xffff_ffff_ffff_ffff]],
+      ].should be_computed_by(:unpack, "R")
+    end
+
+    it "decodes multiple values with '*' modifier" do
+      "\x01\x02".unpack("R*").should == [1, 2]
+      "\x7f\x80\x01".unpack("R*").should == [127, 128]
+    end
+
+    it "returns nil for incomplete data" do
+      "\xFF".unpack("R").should == [nil]
+      "\xFF".unpack1("R").should == nil
+    end
+
+    it "returns nil for remaining incomplete values after a valid one" do
+      bytes = [256].pack("R")
+      (bytes + "\xFF").unpack("RRRR").should == [256, nil, nil, nil]
+    end
+
+    it "skips incomplete values with '*' modifier" do
+      "\xFF".unpack("R*").should == []
+    end
+  end
+
+  describe "String#unpack with format 'r'" do
+    it_behaves_like :string_unpack_basic, 'r'
+    it_behaves_like :string_unpack_no_platform, 'r'
+
+    it "decodes a SLEB128 integer" do
+      [ ["\x00",      [0]],
+        ["\x01",      [1]],
+        ["\x7f",      [-1]],
+        ["\x7e",      [-2]],
+        ["\xff\x00",  [127]],
+        ["\x80\x01",  [128]],
+        ["\x81\x7f",  [-127]],
+        ["\x80\x7f",  [-128]],
+      ].should be_computed_by(:unpack, "r")
+    end
+
+    it "decodes larger numbers" do
+      "\xff\xff\x00".unpack("r").should == [0x3fff]
+      "\x80\x80\x01".unpack("r").should == [0x4000]
+      "\x81\x80\x7f".unpack("r").should == [-0x3fff]
+      "\x80\x80\x7f".unpack("r").should == [-0x4000]
+    end
+
+    it "decodes multiple values with '*' modifier" do
+      "\x00\x01\x7f".unpack("r*").should == [0, 1, -1]
+    end
+
+    it "returns nil for incomplete data" do
+      "\xFF".unpack("r").should == [nil]
+      "\xFF".unpack1("r").should == nil
+    end
+
+    it "returns nil for remaining incomplete values after a valid one" do
+      bytes = [256].pack("r")
+      (bytes + "\xFF").unpack("rrrr").should == [256, nil, nil, nil]
+    end
+
+    it "skips incomplete values with '*' modifier" do
+      "\xFF".unpack("r*").should == []
+    end
+  end
+end
diff --git a/spec/ruby/core/string/unpack/shared/basic.rb b/spec/ruby/core/string/unpack/shared/basic.rb
index 332e39d8d1..2ee2d6899a 100644
--- a/spec/ruby/core/string/unpack/shared/basic.rb
+++ b/spec/ruby/core/string/unpack/shared/basic.rb
@@ -1,29 +1,27 @@
 describe :string_unpack_basic, shared: true do
   it "ignores whitespace in the format string" do
-    "abc".unpack("a \t\n\v\f\r"+unpack_format).should be_an_instance_of(Array)
+    "abc".unpack("a \t\n\v\f\r"+unpack_format).should.instance_of?(Array)
   end
 
   it "calls #to_str to coerce the directives string" do
     d = mock("unpack directive")
     d.should_receive(:to_str).and_return("a"+unpack_format)
-    "abc".unpack(d).should be_an_instance_of(Array)
+    "abc".unpack(d).should.instance_of?(Array)
   end
 
-  it "raises a TypeError when passed nil" do
-    -> { "abc".unpack(nil) }.should raise_error(TypeError)
-  end
-
-  it "raises a TypeError when passed an Integer" do
-    -> { "abc".unpack(1) }.should raise_error(TypeError)
+  it "raises ArgumentError when a directive is unknown" do
+    -> { "abcdefgh".unpack("a K" + unpack_format) }.should.raise(ArgumentError, "unknown unpack directive 'K' in 'a K#{unpack_format}'")
+    -> { "abcdefgh".unpack("a 0" + unpack_format) }.should.raise(ArgumentError, "unknown unpack directive '0' in 'a 0#{unpack_format}'")
+    -> { "abcdefgh".unpack("a :" + unpack_format) }.should.raise(ArgumentError, "unknown unpack directive ':' in 'a :#{unpack_format}'")
   end
 end
 
 describe :string_unpack_no_platform, shared: true do
   it "raises an ArgumentError when the format modifier is '_'" do
-    -> { "abcdefgh".unpack(unpack_format("_")) }.should raise_error(ArgumentError)
+    -> { "abcdefgh".unpack(unpack_format("_")) }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError when the format modifier is '!'" do
-    -> { "abcdefgh".unpack(unpack_format("!")) }.should raise_error(ArgumentError)
+    -> { "abcdefgh".unpack(unpack_format("!")) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/unpack/shared/float.rb b/spec/ruby/core/string/unpack/shared/float.rb
index 99bd8a3401..5525c3fe73 100644
--- a/spec/ruby/core/string/unpack/shared/float.rb
+++ b/spec/ruby/core/string/unpack/shared/float.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :string_unpack_float_le, shared: true do
   it "decodes one float for a single format character" do
@@ -53,12 +53,13 @@ describe :string_unpack_float_le, shared: true do
 
   it "decodes NaN" do
     # mumble mumble NaN mumble https://bugs.ruby-lang.org/issues/5884
-    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should be_true
+    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should == true
   end
 
-  it "ignores NULL bytes between directives" do
-    array = "\x9a\x999@33\xb3?".unpack(unpack_format("\000", 2))
-    array.should == [2.9000000953674316, 1.399999976158142]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x9a\x999@33\xb3?".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -120,12 +121,13 @@ describe :string_unpack_float_be, shared: true do
 
   it "decodes NaN" do
     # mumble mumble NaN mumble https://bugs.ruby-lang.org/issues/5884
-    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should be_true
+    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should == true
   end
 
-  it "ignores NULL bytes between directives" do
-    array = "@9\x99\x9a?\xb333".unpack(unpack_format("\000", 2))
-    array.should == [2.9000000953674316, 1.399999976158142]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "@9\x99\x9a?\xb333".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -190,11 +192,13 @@ describe :string_unpack_double_le, shared: true do
 
   it "decodes NaN" do
     # mumble mumble NaN mumble https://bugs.ruby-lang.org/issues/5884
-    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should be_true
+    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should == true
   end
 
-  it "ignores NULL bytes between directives" do
-    "333333\x07@ffffff\xf6?".unpack(unpack_format("\000", 2)).should == [2.9, 1.4]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "333333\x07@ffffff\xf6?".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -258,11 +262,13 @@ describe :string_unpack_double_be, shared: true do
 
   it "decodes NaN" do
     # mumble mumble NaN mumble https://bugs.ruby-lang.org/issues/5884
-    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should be_true
+    [nan_value].pack(unpack_format).unpack(unpack_format).first.nan?.should == true
   end
 
-  it "ignores NULL bytes between directives" do
-    "@\x07333333?\xf6ffffff".unpack(unpack_format("\000", 2)).should == [2.9, 1.4]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "@\x07333333?\xf6ffffff".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/string/unpack/shared/integer.rb b/spec/ruby/core/string/unpack/shared/integer.rb
index cbaa743683..c66156536b 100644
--- a/spec/ruby/core/string/unpack/shared/integer.rb
+++ b/spec/ruby/core/string/unpack/shared/integer.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 describe :string_unpack_16bit_le, shared: true do
   it "decodes one short for a single format character" do
@@ -32,8 +32,10 @@ describe :string_unpack_16bit_le, shared: true do
     ].should be_computed_by(:unpack, unpack_format(3))
   end
 
-  it "ignores NULL bytes between directives" do
-    "abcd".unpack(unpack_format("\000", 2)).should == [25185, 25699]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "abcd".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -85,8 +87,10 @@ describe :string_unpack_16bit_be, shared: true do
     ].should be_computed_by(:unpack, unpack_format(3))
   end
 
-  it "ignores NULL bytes between directives" do
-    "badc".unpack(unpack_format("\000", 2)).should == [25185, 25699]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "badc".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -139,8 +143,10 @@ describe :string_unpack_32bit_le, shared: true do
     ].should be_computed_by(:unpack, unpack_format(3))
   end
 
-  it "ignores NULL bytes between directives" do
-    "abcdefgh".unpack(unpack_format("\000", 2)).should == [1684234849, 1751606885]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "abcdefgh".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -193,8 +199,10 @@ describe :string_unpack_32bit_be, shared: true do
     ].should be_computed_by(:unpack, unpack_format(3))
   end
 
-  it "ignores NULL bytes between directives" do
-    "dcbahgfe".unpack(unpack_format("\000", 2)).should == [1684234849, 1751606885]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "dcbahgfe".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -243,9 +251,10 @@ describe :string_unpack_64bit_le, shared: true do
     "abc".unpack(unpack_format('*')).should == []
   end
 
-  it "ignores NULL bytes between directives" do
-    array = "abcdefghabghefcd".unpack(unpack_format("\000", 2))
-    array.should == [7523094288207667809, 7233738012216484449]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "badc".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
@@ -305,9 +314,10 @@ describe :string_unpack_64bit_be, shared: true do
     "abc".unpack(unpack_format('*')).should == []
   end
 
-  it "ignores NULL bytes between directives" do
-    array = "hgfedcbadcfehgba".unpack(unpack_format("\000", 2))
-    array.should == [7523094288207667809, 7233738012216484449]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "hgfedcbadcfehgba".unpack(unpack_format("\000", 2))
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/string/unpack/shared/taint.rb b/spec/ruby/core/string/unpack/shared/taint.rb
index 391338192a..79c7251f01 100644
--- a/spec/ruby/core/string/unpack/shared/taint.rb
+++ b/spec/ruby/core/string/unpack/shared/taint.rb
@@ -1,81 +1,2 @@
 describe :string_unpack_taint, shared: true do
-  it "does not taint returned arrays if given an untainted format string" do
-    "".unpack(unpack_format(2)).tainted?.should be_false
-  end
-
-  it "does not taint returned arrays if given a tainted format string" do
-    format_string = unpack_format(2).dup
-    format_string.taint
-    "".unpack(format_string).tainted?.should be_false
-  end
-
-  it "does not taint returned strings if given an untainted format string" do
-    "".unpack(unpack_format(2)).any?(&:tainted?).should be_false
-  end
-
-  it "does not taint returned strings if given a tainted format string" do
-    format_string = unpack_format(2).dup
-    format_string.taint
-    "".unpack(format_string).any?(&:tainted?).should be_false
-  end
-
-  it "does not taint returned arrays if given an untainted packed string" do
-    "".unpack(unpack_format(2)).tainted?.should be_false
-  end
-
-  it "does not taint returned arrays if given a tainted packed string" do
-    packed_string = ""
-    packed_string.taint
-    packed_string.unpack(unpack_format(2)).tainted?.should be_false
-  end
-
-  it "does not taint returned strings if given an untainted packed string" do
-    "".unpack(unpack_format(2)).any?(&:tainted?).should be_false
-  end
-
-  it "taints returned strings if given a tainted packed string" do
-    packed_string = ""
-    packed_string.taint
-    packed_string.unpack(unpack_format(2)).all?(&:tainted?).should be_true
-  end
-
-  it "does not untrust returned arrays if given an untrusted format string" do
-    "".unpack(unpack_format(2)).untrusted?.should be_false
-  end
-
-  it "does not untrust returned arrays if given a untrusted format string" do
-    format_string = unpack_format(2).dup
-    format_string.untrust
-    "".unpack(format_string).untrusted?.should be_false
-  end
-
-  it "does not untrust returned strings if given an untainted format string" do
-    "".unpack(unpack_format(2)).any?(&:untrusted?).should be_false
-  end
-
-  it "does not untrust returned strings if given a untrusted format string" do
-    format_string = unpack_format(2).dup
-    format_string.untrust
-    "".unpack(format_string).any?(&:untrusted?).should be_false
-  end
-
-  it "does not untrust returned arrays if given an trusted packed string" do
-    "".unpack(unpack_format(2)).untrusted?.should be_false
-  end
-
-  it "does not untrust returned arrays if given a untrusted packed string" do
-    packed_string = ""
-    packed_string.untrust
-    packed_string.unpack(unpack_format(2)).untrusted?.should be_false
-  end
-
-  it "does not untrust returned strings if given an trusted packed string" do
-    "".unpack(unpack_format(2)).any?(&:untrusted?).should be_false
-  end
-
-  it "untrusts returned strings if given a untrusted packed string" do
-    packed_string = ""
-    packed_string.untrust
-    packed_string.unpack(unpack_format(2)).all?(&:untrusted?).should be_true
-  end
 end
diff --git a/spec/ruby/core/string/unpack/shared/unicode.rb b/spec/ruby/core/string/unpack/shared/unicode.rb
index a2b4e142b2..9b4e0c09de 100644
--- a/spec/ruby/core/string/unpack/shared/unicode.rb
+++ b/spec/ruby/core/string/unpack/shared/unicode.rb
@@ -50,8 +50,10 @@ describe :string_unpack_unicode, shared: true do
     "\xc2\x80".unpack("UUUU").should == [0x80]
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x01\x02".unpack("U\x00U").should == [1, 2]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x01\x02".unpack("U\x00U")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
diff --git a/spec/ruby/core/string/unpack/u_spec.rb b/spec/ruby/core/string/unpack/u_spec.rb
index 7845e6d5f2..720c1b8583 100644
--- a/spec/ruby/core/string/unpack/u_spec.rb
+++ b/spec/ruby/core/string/unpack/u_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -12,11 +12,11 @@ describe "String#unpack with format 'U'" do
   it_behaves_like :string_unpack_taint, 'U'
 
   it "raises ArgumentError on a malformed byte sequence" do
-    -> { "\xE3".unpack('U') }.should raise_error(ArgumentError)
+    -> { "\xE3".unpack('U') }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError on a malformed byte sequence and doesn't continue when used with the * modifier" do
-    -> { "\xE3".unpack('U*') }.should raise_error(ArgumentError)
+    -> { "\xE3".unpack('U*') }.should.raise(ArgumentError)
   end
 end
 
@@ -33,7 +33,7 @@ describe "String#unpack with format 'u'" do
     str = "".unpack("u")[0]
     str.encoding.should == Encoding::BINARY
 
-    str = "1".force_encoding('UTF-8').unpack("u")[0]
+    str = "1".dup.force_encoding('UTF-8').unpack("u")[0]
     str.encoding.should == Encoding::BINARY
   end
 
diff --git a/spec/ruby/core/string/unpack/w_spec.rb b/spec/ruby/core/string/unpack/w_spec.rb
index 166ae58869..cc9aecac9c 100644
--- a/spec/ruby/core/string/unpack/w_spec.rb
+++ b/spec/ruby/core/string/unpack/w_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -15,11 +15,23 @@ describe "String#unpack with directive 'w'" do
     ].should be_computed_by(:unpack, "w")
   end
 
-  it "ignores NULL bytes between directives" do
-    "\x01\x02\x03".unpack("w\x00w").should == [1, 2]
+  it "raise ArgumentError for NULL bytes between directives" do
+    -> {
+      "\x01\x02\x03".unpack("w\x00w")
+    }.should.raise(ArgumentError, /unknown unpack directive/)
   end
 
   it "ignores spaces between directives" do
     "\x01\x02\x03".unpack("w w").should == [1, 2]
   end
 end
+
+describe "String#unpack with directive 'w*'" do
+
+  it "decodes BER-compressed integers" do
+    "\x01\x02\x03\x04".unpack("w*").should == [1, 2, 3, 4]
+    "\x00\xCE\x0F\x84\x80\x80\x80\x80\x80\x80\x80\x80\x00\x01\x00".unpack("w*").should == [0, 9999, 2**65, 1, 0]
+    "\x81\x80\x80\x80\x80\x80\x80\x80\x80\x00\x90\x80\x80\x80\x80\x80\x80\x80\x03\x01\x02".unpack("w*").should == [2**63, (2**60 + 3), 1, 2]
+  end
+
+end
diff --git a/spec/ruby/core/string/unpack/x_spec.rb b/spec/ruby/core/string/unpack/x_spec.rb
index 5e248de77e..fb2e79fc1f 100644
--- a/spec/ruby/core/string/unpack/x_spec.rb
+++ b/spec/ruby/core/string/unpack/x_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -24,11 +24,11 @@ describe "String#unpack with format 'X'" do
   end
 
   it "raises an ArgumentError when passed the '*' modifier if the remaining bytes exceed the bytes from the index to the start of the String" do
-    -> { "abcd".unpack("CX*C") }.should raise_error(ArgumentError)
+    -> { "abcd".unpack("CX*C") }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError if the count exceeds the bytes from current index to the start of the String" do
-    -> { "\x01\x02\x03\x04".unpack("C3X4C") }.should raise_error(ArgumentError)
+    -> { "\x01\x02\x03\x04".unpack("C3X4C") }.should.raise(ArgumentError)
   end
 end
 
@@ -57,6 +57,6 @@ describe "String#unpack with format 'x'" do
   end
 
   it "raises an ArgumentError if the count exceeds the size of the String" do
-    -> { "\x01\x02\x03\x04".unpack("C2x3C") }.should raise_error(ArgumentError)
+    -> { "\x01\x02\x03\x04".unpack("C2x3C") }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/unpack/z_spec.rb b/spec/ruby/core/string/unpack/z_spec.rb
index 552851ce04..1030390550 100644
--- a/spec/ruby/core/string/unpack/z_spec.rb
+++ b/spec/ruby/core/string/unpack/z_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 require_relative 'shared/basic'
@@ -20,4 +20,9 @@ describe "String#unpack with format 'Z'" do
       ["\x00a\x00 bc \x00",  ["", "c"]]
     ].should be_computed_by(:unpack, "Z5Z")
   end
+
+  it "does not advance past the null byte when given a 'Z' format specifier" do
+    "a\x00\x0f".unpack('Zxc').should == ['a', 15]
+    "a\x00\x0f".unpack('Zcc').should == ['a', 0, 15]
+  end
 end
diff --git a/spec/ruby/core/string/unpack1_spec.rb b/spec/ruby/core/string/unpack1_spec.rb
index 5fe81733fb..ee10042eb8 100644
--- a/spec/ruby/core/string/unpack1_spec.rb
+++ b/spec/ruby/core/string/unpack1_spec.rb
@@ -7,4 +7,55 @@ describe "String#unpack1" do
     "aG9nZWZ1Z2E=".unpack1("m").should == "hogefuga"
     "A".unpack1("B*").should == "01000001"
   end
+
+  it "starts unpacking from the given offset" do
+    "ZZABCD".unpack1('x3C', offset: 2).should == "ABCD".unpack('x3C')[0]
+    "ZZZZaG9nZWZ1Z2E=".unpack1("m", offset: 4).should == "hogefuga"
+    "ZA".unpack1("B*", offset: 1).should == "01000001"
+  end
+
+  it "traits offset as a bytes offset" do
+    "؈".unpack("CC").should == [216, 136]
+    "؈".unpack1("C").should == 216
+    "؈".unpack1("C", offset: 1).should == 136
+  end
+
+  describe "when the offset is negative" do
+    ruby_version_is "4.1" do
+      it "starts unpacking from the end" do
+        "abc".unpack1("C", offset: -2).should == 98
+      end
+
+      it "raises an ArgumentError if it is less than -length" do
+        -> { "a".unpack1("C", offset: -2) }.should.raise(ArgumentError, "offset outside of string")
+      end
+    end
+
+    ruby_version_is ""..."4.1" do
+      it "raises an ArgumentError" do
+        -> { "a".unpack1("C", offset: -1) }.should.raise(ArgumentError, "offset can't be negative")
+      end
+    end
+  end
+
+  it "returns nil if the offset is at the end of the string" do
+    "a".unpack1("C", offset: 1).should == nil
+  end
+
+  it "raises an ArgumentError when the offset is larger than the string bytesize" do
+    -> { "a".unpack1("C", offset: 2) }.should.raise(ArgumentError, "offset outside of string")
+  end
+
+  context "with format 'm0'" do
+    # unpack1("m0") takes a special code path that calls Pack.unpackBase46Strict instead of Pack.unpack_m,
+    # which is why we repeat the tests for unpack("m0") here.
+
+    it "decodes base64" do
+      "dGVzdA==".unpack1("m0").should == "test"
+    end
+
+    it "raises an ArgumentError for an invalid base64 character" do
+      -> { "dGV%zdA==".unpack1("m0") }.should.raise(ArgumentError)
+    end
+  end
 end
diff --git a/spec/ruby/core/string/unpack_spec.rb b/spec/ruby/core/string/unpack_spec.rb
new file mode 100644
index 0000000000..eb4710ce14
--- /dev/null
+++ b/spec/ruby/core/string/unpack_spec.rb
@@ -0,0 +1,46 @@
+require_relative '../../spec_helper'
+
+describe "String#unpack" do
+  it "raises a TypeError when passed nil" do
+    -> { "abc".unpack(nil) }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError when passed an Integer" do
+    -> { "abc".unpack(1) }.should.raise(TypeError)
+  end
+
+  it "starts unpacking from the given offset" do
+    "abc".unpack("CC", offset: 1).should == [98, 99]
+  end
+
+  it "traits offset as a bytes offset" do
+    "؈".unpack("CC").should == [216, 136]
+    "؈".unpack("CC", offset: 1).should == [136, nil]
+  end
+
+  describe "when the offset is negative" do
+    ruby_version_is "4.1" do
+      it "starts unpacking from the end" do
+        "abc".unpack("CC", offset: -2).should == [98, 99]
+      end
+
+      it "raises an ArgumentError if it is less than -length" do
+        -> { "a".unpack("C", offset: -2) }.should.raise(ArgumentError, "offset outside of string")
+      end
+    end
+
+    ruby_version_is ""..."4.1" do
+      it "raises an ArgumentError" do
+        -> { "a".unpack("C", offset: -1) }.should.raise(ArgumentError, "offset can't be negative")
+      end
+    end
+  end
+
+  it "returns nil if the offset is at the end of the string" do
+    "a".unpack("C", offset: 1).should == [nil]
+  end
+
+  it "raises an ArgumentError when the offset is larger than the string" do
+    -> { "a".unpack("C", offset: 2) }.should.raise(ArgumentError, "offset outside of string")
+  end
+end
diff --git a/spec/ruby/core/string/upcase_spec.rb b/spec/ruby/core/string/upcase_spec.rb
index 72aacd88a9..a6e1869267 100644
--- a/spec/ruby/core/string/upcase_spec.rb
+++ b/spec/ruby/core/string/upcase_spec.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
@@ -8,6 +9,10 @@ describe "String#upcase" do
     "hello".upcase.should == "HELLO"
   end
 
+  it "returns a String in the same encoding as self" do
+    "hello".encode("US-ASCII").upcase.encoding.should == Encoding::US_ASCII
+  end
+
   describe "full Unicode case mapping" do
     it "works for all of Unicode with no option" do
       "äöü".upcase.should == "ÄÖÜ"
@@ -19,7 +24,7 @@ describe "String#upcase" do
       upcased.should == "ASSET"
       upcased.size.should == 5
       upcased.bytesize.should == 5
-      upcased.ascii_only?.should be_true
+      upcased.ascii_only?.should == true
     end
   end
 
@@ -27,6 +32,10 @@ describe "String#upcase" do
     it "does not upcase non-ASCII characters" do
       "aßet".upcase(:ascii).should == "AßET"
     end
+
+    it "works with substrings" do
+      "prefix té"[-2..-1].upcase(:ascii).should == "Té"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
@@ -39,7 +48,7 @@ describe "String#upcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "i".upcase(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { "i".upcase(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -53,36 +62,36 @@ describe "String#upcase" do
     end
 
     it "does not allow any other additional option" do
-      -> { "iß".upcase(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { "iß".upcase(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { "abc".upcase(:fold) }.should raise_error(ArgumentError)
+    -> { "abc".upcase(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { "abc".upcase(:invalid_option) }.should raise_error(ArgumentError)
+    -> { "abc".upcase(:invalid_option) }.should.raise(ArgumentError)
   end
 
-  it "taints result when self is tainted" do
-    "".taint.upcase.tainted?.should == true
-    "X".taint.upcase.tainted?.should == true
-    "x".taint.upcase.tainted?.should == true
-  end
-
-  it "returns a subclass instance for subclasses" do
-    StringSpecs::MyString.new("fooBAR").upcase.should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String instance for subclasses" do
+    StringSpecs::MyString.new("fooBAR").upcase.should.instance_of?(String)
   end
 end
 
 describe "String#upcase!" do
   it "modifies self in place" do
     a = "HeLlO"
-    a.upcase!.should equal(a)
+    a.upcase!.should.equal?(a)
     a.should == "HELLO"
   end
 
+  it "modifies self in place for non-ascii-compatible encodings" do
+    a = "HeLlO".encode("utf-16le")
+    a.upcase!
+    a.should == "HELLO".encode("utf-16le")
+  end
+
   describe "full Unicode case mapping" do
     it "modifies self in place for all of Unicode with no option" do
       a = "äöü"
@@ -90,6 +99,12 @@ describe "String#upcase!" do
       a.should == "ÄÖÜ"
     end
 
+    it "works for non-ascii-compatible encodings" do
+      a = "äöü".encode("utf-16le")
+      a.upcase!
+      a.should == "ÄÖÜ".encode("utf-16le")
+    end
+
     it "updates string metadata for self" do
       upcased = "aßet"
       upcased.upcase!
@@ -97,7 +112,7 @@ describe "String#upcase!" do
       upcased.should == "ASSET"
       upcased.size.should == 5
       upcased.bytesize.should == 5
-      upcased.ascii_only?.should be_true
+      upcased.ascii_only?.should == true
     end
   end
 
@@ -107,6 +122,12 @@ describe "String#upcase!" do
       a.upcase!(:ascii)
       a.should == "AßET"
     end
+
+    it "works for non-ascii-compatible encodings" do
+      a = "abc".encode("utf-16le")
+      a.upcase!(:ascii)
+      a.should == "ABC".encode("utf-16le")
+    end
   end
 
   describe "modifies self in place for full Unicode case mapping adapted for Turkic languages" do
@@ -123,7 +144,7 @@ describe "String#upcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "i"; a.upcase!(:turkic, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "i"; a.upcase!(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
@@ -141,16 +162,16 @@ describe "String#upcase!" do
     end
 
     it "does not allow any other additional option" do
-      -> { a = "iß"; a.upcase!(:lithuanian, :ascii) }.should raise_error(ArgumentError)
+      -> { a = "iß"; a.upcase!(:lithuanian, :ascii) }.should.raise(ArgumentError)
     end
   end
 
   it "does not allow the :fold option for upcasing" do
-    -> { a = "abc"; a.upcase!(:fold) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.upcase!(:fold) }.should.raise(ArgumentError)
   end
 
   it "does not allow invalid options" do
-    -> { a = "abc"; a.upcase!(:invalid_option) }.should raise_error(ArgumentError)
+    -> { a = "abc"; a.upcase!(:invalid_option) }.should.raise(ArgumentError)
   end
 
   it "returns nil if no modifications were made" do
@@ -159,8 +180,8 @@ describe "String#upcase!" do
     a.should == "HELLO"
   end
 
-  it "raises a #{frozen_error_class} when self is frozen" do
-    -> { "HeLlo".freeze.upcase! }.should raise_error(frozen_error_class)
-    -> { "HELLO".freeze.upcase! }.should raise_error(frozen_error_class)
+  it "raises a FrozenError when self is frozen" do
+    -> { "HeLlo".freeze.upcase! }.should.raise(FrozenError)
+    -> { "HELLO".freeze.upcase! }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/string/uplus_spec.rb b/spec/ruby/core/string/uplus_spec.rb
index a7402b4549..20767bcc01 100644
--- a/spec/ruby/core/string/uplus_spec.rb
+++ b/spec/ruby/core/string/uplus_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative '../../spec_helper'
 
 describe 'String#+@' do
@@ -5,18 +6,55 @@ describe 'String#+@' do
     input  = 'foo'.freeze
     output = +input
 
-    output.frozen?.should == false
+    output.should_not.frozen?
     output.should == 'foo'
+
+    output << 'bar'
+    output.should == 'foobar'
   end
 
-  it 'returns self if the String is not frozen' do
-    input  = 'foo'
+  it 'returns a mutable String itself' do
+    input = String.new("foo")
     output = +input
 
-    output.equal?(input).should == true
+    output.should.equal?(input)
+
+    input << "bar"
+    output.should == "foobar"
+  end
+
+  context 'if file has "frozen_string_literal: true" magic comment' do
+    it 'returns mutable copy of a literal' do
+      ruby_exe(fixture(__FILE__, "freeze_magic_comment.rb")).should == 'mutable'
+    end
   end
 
-  it 'returns mutable copy despite freeze-magic-comment in file' do
-    ruby_exe(fixture(__FILE__, "freeze_magic_comment.rb")).should == 'mutable'
+  context 'if file has "frozen_string_literal: false" magic comment' do
+    it 'returns literal string itself' do
+      input  = 'foo'
+      output = +input
+
+      output.equal?(input).should == true
+    end
+  end
+
+  context 'if file has no frozen_string_literal magic comment' do
+    ruby_version_is ''...'3.4' do
+      it 'returns literal string itself' do
+        eval(<<~RUBY).should == true
+          s = "foo"
+          s.equal?(+s)
+        RUBY
+      end
+    end
+
+    ruby_version_is '3.4' do
+      it 'returns mutable copy of a literal' do
+        eval(<<~RUBY).should == false
+          s = "foo"
+          s.equal?(+s)
+        RUBY
+      end
+    end
   end
 end
diff --git a/spec/ruby/core/string/upto_spec.rb b/spec/ruby/core/string/upto_spec.rb
index b988613a80..2eea06fd01 100644
--- a/spec/ruby/core/string/upto_spec.rb
+++ b/spec/ruby/core/string/upto_spec.rb
@@ -53,13 +53,13 @@ describe "String#upto" do
   end
 
   it "raises a TypeError if other can't be converted to a string" do
-    -> { "abc".upto(123) { }      }.should raise_error(TypeError)
-    -> { "abc".upto(mock('x')){ } }.should raise_error(TypeError)
+    -> { "abc".upto(123) { }      }.should.raise(TypeError)
+    -> { "abc".upto(mock('x')){ } }.should.raise(TypeError)
   end
 
 
   it "does not work with symbols" do
-    -> { "a".upto(:c).to_a }.should raise_error(TypeError)
+    -> { "a".upto(:c).to_a }.should.raise(TypeError)
   end
 
   it "returns non-alphabetic characters in the ASCII range for single letters" do
@@ -74,6 +74,18 @@ describe "String#upto" do
     a.should == ["a", "b", "c"]
   end
 
+  it "works with non-ASCII ranges" do
+    a = []
+    'Σ'.upto('Ω') { |s| a << s }
+    a.should == ["Σ", "Τ", "Υ", "Φ", "Χ", "Ψ", "Ω"]
+  end
+
+  it "raises Encoding::CompatibilityError when incompatible characters are given" do
+    char1 = 'a'.dup.force_encoding("EUC-JP")
+    char2 = 'b'.dup.force_encoding("ISO-2022-JP")
+    -> { char1.upto(char2) {} }.should.raise(Encoding::CompatibilityError, "incompatible character encodings: EUC-JP and ISO-2022-JP")
+  end
+
   describe "on sequence of numbers" do
     it "calls the block as Integer#upto"  do
       "8".upto("11").to_a.should == 8.upto(11).map(&:to_s)
@@ -83,7 +95,7 @@ describe "String#upto" do
   describe "when no block is given" do
     it "returns an enumerator" do
       enum = "aaa".upto("baa", true)
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.count.should == 26**2
     end
 
diff --git a/spec/ruby/core/string/valid_encoding/utf_8_spec.rb b/spec/ruby/core/string/valid_encoding/utf_8_spec.rb
new file mode 100644
index 0000000000..a14c3af830
--- /dev/null
+++ b/spec/ruby/core/string/valid_encoding/utf_8_spec.rb
@@ -0,0 +1,214 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../../spec_helper'
+
+describe "String#valid_encoding? and UTF-8" do
+  def utf8(bytes)
+    bytes.pack("C*").force_encoding("UTF-8")
+  end
+
+  describe "1-byte character" do
+    it "is valid if is in format 0xxxxxxx" do
+      utf8([0b00000000]).valid_encoding?.should == true
+      utf8([0b01111111]).valid_encoding?.should == true
+    end
+
+    it "is not valid if is not in format 0xxxxxxx" do
+      utf8([0b10000000]).valid_encoding?.should == false
+      utf8([0b11111111]).valid_encoding?.should == false
+    end
+  end
+
+  describe "2-bytes character" do
+    it "is valid if in format [110xxxxx 10xxxxx]" do
+      utf8([0b11000010, 0b10000000]).valid_encoding?.should == true
+      utf8([0b11000010, 0b10111111]).valid_encoding?.should == true
+
+      utf8([0b11011111, 0b10000000]).valid_encoding?.should == true
+      utf8([0b11011111, 0b10111111]).valid_encoding?.should == true
+    end
+
+    it "is not valid if the first byte is not in format 110xxxxx" do
+      utf8([0b00000010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b00100010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01000010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01100010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10000010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10100010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11000010, 0b10000000]).valid_encoding?.should == true # correct bytes
+      utf8([0b11100010, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is not in format 10xxxxxx" do
+      utf8([0b11000010, 0b00000000]).valid_encoding?.should == false
+      utf8([0b11000010, 0b01000000]).valid_encoding?.should == false
+      utf8([0b11000010, 0b11000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if is smaller than [xxxxxx10 xx000000] (codepoints < U+007F, that are encoded with the 1-byte format)" do
+      utf8([0b11000000, 0b10111111]).valid_encoding?.should == false
+      utf8([0b11000001, 0b10111111]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the first byte is missing" do
+      bytes = [0b11000010, 0b10000000]
+      utf8(bytes[1..1]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is missing" do
+      bytes = [0b11000010, 0b10000000]
+      utf8(bytes[0..0]).valid_encoding?.should == false
+    end
+  end
+
+  describe "3-bytes character" do
+    it "is valid if in format [1110xxxx 10xxxxxx 10xxxxxx]" do
+      utf8([0b11100000, 0b10100000, 0b10000000]).valid_encoding?.should == true
+      utf8([0b11100000, 0b10100000, 0b10111111]).valid_encoding?.should == true
+      utf8([0b11100000, 0b10111111, 0b10111111]).valid_encoding?.should == true
+      utf8([0b11101111, 0b10111111, 0b10111111]).valid_encoding?.should == true
+    end
+
+    it "is not valid if the first byte is not in format 1110xxxx" do
+      utf8([0b00000000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b00010000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b00100000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b00110000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01000000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01010000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01100000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01110000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10000000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10010000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10100000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10110000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11000000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11010000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10100000, 0b10000000]).valid_encoding?.should == true # correct bytes
+      utf8([0b11110000, 0b10100000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is not in format 10xxxxxx" do
+      utf8([0b11100000, 0b00100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b01100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b11100000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the third byte is not in format 10xxxxxx" do
+      utf8([0b11100000, 0b10100000, 0b00000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10100000, 0b01000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10100000, 0b01000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if is smaller than [xxxx0000 xx100000 xx000000] (codepoints < U+07FF that are encoded with the 2-byte format)" do
+      utf8([0b11100000, 0b10010000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10001000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10000100, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10000010, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10000001, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11100000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if in range [xxxx1101 xx100000 xx000000] - [xxxx1101 xx111111 xx111111] (codepoints U+D800 - U+DFFF)" do
+      utf8([0b11101101, 0b10100000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11101101, 0b10100000, 0b10000001]).valid_encoding?.should == false
+      utf8([0b11101101, 0b10111111, 0b10111111]).valid_encoding?.should == false
+
+      utf8([0b11101101, 0b10011111, 0b10111111]).valid_encoding?.should == true # lower boundary - 1
+      utf8([0b11101110, 0b10000000, 0b10000000]).valid_encoding?.should == true # upper boundary + 1
+    end
+
+    it "is not valid if the first byte is missing" do
+      bytes = [0b11100000, 0b10100000, 0b10000000]
+      utf8(bytes[2..3]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is missing" do
+      bytes = [0b11100000, 0b10100000, 0b10000000]
+      utf8([bytes[0], bytes[2]]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second and the third bytes are missing" do
+      bytes = [0b11100000, 0b10100000, 0b10000000]
+      utf8(bytes[0..0]).valid_encoding?.should == false
+    end
+  end
+
+  describe "4-bytes character" do
+    it "is valid if in format [11110xxx 10xxxxxx 10xxxxxx 10xxxxxx]" do
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == true
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b10111111]).valid_encoding?.should == true
+      utf8([0b11110000, 0b10010000, 0b10111111, 0b10111111]).valid_encoding?.should == true
+      utf8([0b11110000, 0b10111111, 0b10111111, 0b10111111]).valid_encoding?.should == true
+      utf8([0b11110100, 0b10001111, 0b10111111, 0b10111111]).valid_encoding?.should == true
+    end
+
+    it "is not valid if the first byte is not in format 11110xxx" do
+      utf8([0b11100000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11010000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b10110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b01110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is not in format 10xxxxxx" do
+      utf8([0b11110000, 0b00010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b01010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == true # correct bytes
+      utf8([0b11110000, 0b11010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the third byte is not in format 10xxxxxx" do
+      utf8([0b11110000, 0b10010000, 0b00000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10010000, 0b01000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == true # correct bytes
+      utf8([0b11110000, 0b10010000, 0b11000000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the forth byte is not in format 10xxxxxx" do
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b00000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b01000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == true # correct bytes
+      utf8([0b11110000, 0b10010000, 0b10000000, 0b11000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if is smaller than [xxxxx000 xx001000 xx000000 xx000000] (codepoint < U+10000)" do
+      utf8([0b11110000, 0b10000111, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000110, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000101, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000100, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000011, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000010, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000001, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110000, 0b10000000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+    end
+
+    it "is not valid if is greater than [xxxxx100 xx001111 xx111111 xx111111] (codepoint > U+10FFFF)" do
+      utf8([0b11110100, 0b10010000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110100, 0b10100000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+      utf8([0b11110100, 0b10110000, 0b10000000, 0b10000000]).valid_encoding?.should == false
+
+      utf8([0b11110101, 0b10001111, 0b10111111, 0b10111111]).valid_encoding?.should == false
+      utf8([0b11110110, 0b10001111, 0b10111111, 0b10111111]).valid_encoding?.should == false
+      utf8([0b11110111, 0b10001111, 0b10111111, 0b10111111]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the first byte is missing" do
+      bytes = [0b11110000, 0b10010000, 0b10000000, 0b10000000]
+      utf8(bytes[1..3]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second byte is missing" do
+      bytes = [0b11110000, 0b10010000, 0b10000000, 0b10000000]
+      utf8([bytes[0], bytes[2], bytes[3]]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second and the third bytes are missing" do
+      bytes = [0b11110000, 0b10010000, 0b10000000, 0b10000000]
+      utf8([bytes[0], bytes[3]]).valid_encoding?.should == false
+    end
+
+    it "is not valid if the second, the third and the fourth bytes are missing" do
+      bytes = [0b11110000, 0b10010000, 0b10000000, 0b10000000]
+      utf8(bytes[0..0]).valid_encoding?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/string/valid_encoding_spec.rb b/spec/ruby/core/string/valid_encoding_spec.rb
index 09916df079..f29220fc99 100644
--- a/spec/ruby/core/string/valid_encoding_spec.rb
+++ b/spec/ruby/core/string/valid_encoding_spec.rb
@@ -2,126 +2,132 @@ require_relative '../../spec_helper'
 
 describe "String#valid_encoding?" do
   it "returns true if the String's encoding is valid" do
-    "a".valid_encoding?.should be_true
-    "\u{8365}\u{221}".valid_encoding?.should be_true
+    "a".valid_encoding?.should == true
+    "\u{8365}\u{221}".valid_encoding?.should == true
   end
 
   it "returns true if self is valid in the current encoding and other encodings" do
-    str = "\x77"
-    str.force_encoding('utf-8').valid_encoding?.should be_true
-    str.force_encoding('binary').valid_encoding?.should be_true
+    str = +"\x77"
+    str.force_encoding('utf-8').valid_encoding?.should == true
+    str.force_encoding('binary').valid_encoding?.should == true
   end
 
   it "returns true for all encodings self is valid in" do
-    str = "\u{6754}"
-    str.force_encoding('BINARY').valid_encoding?.should be_true
-    str.force_encoding('UTF-8').valid_encoding?.should be_true
-    str.force_encoding('US-ASCII').valid_encoding?.should be_false
-    str.force_encoding('Big5').valid_encoding?.should be_false
-    str.force_encoding('CP949').valid_encoding?.should be_false
-    str.force_encoding('Emacs-Mule').valid_encoding?.should be_false
-    str.force_encoding('EUC-JP').valid_encoding?.should be_false
-    str.force_encoding('EUC-KR').valid_encoding?.should be_false
-    str.force_encoding('EUC-TW').valid_encoding?.should be_false
-    str.force_encoding('GB18030').valid_encoding?.should be_false
-    str.force_encoding('GBK').valid_encoding?.should be_false
-    str.force_encoding('ISO-8859-1').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-2').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-3').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-4').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-5').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-6').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-7').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-8').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-9').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-10').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-11').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-13').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-14').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-15').valid_encoding?.should be_true
-    str.force_encoding('ISO-8859-16').valid_encoding?.should be_true
-    str.force_encoding('KOI8-R').valid_encoding?.should be_true
-    str.force_encoding('KOI8-U').valid_encoding?.should be_true
-    str.force_encoding('Shift_JIS').valid_encoding?.should be_false
-    str.force_encoding('UTF-16BE').valid_encoding?.should be_false
-    str.force_encoding('UTF-16LE').valid_encoding?.should be_false
-    str.force_encoding('UTF-32BE').valid_encoding?.should be_false
-    str.force_encoding('UTF-32LE').valid_encoding?.should be_false
-    str.force_encoding('Windows-1251').valid_encoding?.should be_true
-    str.force_encoding('IBM437').valid_encoding?.should be_true
-    str.force_encoding('IBM737').valid_encoding?.should be_true
-    str.force_encoding('IBM775').valid_encoding?.should be_true
-    str.force_encoding('CP850').valid_encoding?.should be_true
-    str.force_encoding('IBM852').valid_encoding?.should be_true
-    str.force_encoding('CP852').valid_encoding?.should be_true
-    str.force_encoding('IBM855').valid_encoding?.should be_true
-    str.force_encoding('CP855').valid_encoding?.should be_true
-    str.force_encoding('IBM857').valid_encoding?.should be_true
-    str.force_encoding('IBM860').valid_encoding?.should be_true
-    str.force_encoding('IBM861').valid_encoding?.should be_true
-    str.force_encoding('IBM862').valid_encoding?.should be_true
-    str.force_encoding('IBM863').valid_encoding?.should be_true
-    str.force_encoding('IBM864').valid_encoding?.should be_true
-    str.force_encoding('IBM865').valid_encoding?.should be_true
-    str.force_encoding('IBM866').valid_encoding?.should be_true
-    str.force_encoding('IBM869').valid_encoding?.should be_true
-    str.force_encoding('Windows-1258').valid_encoding?.should be_true
-    str.force_encoding('GB1988').valid_encoding?.should be_true
-    str.force_encoding('macCentEuro').valid_encoding?.should be_true
-    str.force_encoding('macCroatian').valid_encoding?.should be_true
-    str.force_encoding('macCyrillic').valid_encoding?.should be_true
-    str.force_encoding('macGreek').valid_encoding?.should be_true
-    str.force_encoding('macIceland').valid_encoding?.should be_true
-    str.force_encoding('macRoman').valid_encoding?.should be_true
-    str.force_encoding('macRomania').valid_encoding?.should be_true
-    str.force_encoding('macThai').valid_encoding?.should be_true
-    str.force_encoding('macTurkish').valid_encoding?.should be_true
-    str.force_encoding('macUkraine').valid_encoding?.should be_true
-    str.force_encoding('stateless-ISO-2022-JP').valid_encoding?.should be_false
-    str.force_encoding('eucJP-ms').valid_encoding?.should be_false
-    str.force_encoding('CP51932').valid_encoding?.should be_false
-    str.force_encoding('GB2312').valid_encoding?.should be_false
-    str.force_encoding('GB12345').valid_encoding?.should be_false
-    str.force_encoding('ISO-2022-JP').valid_encoding?.should be_true
-    str.force_encoding('ISO-2022-JP-2').valid_encoding?.should be_true
-    str.force_encoding('CP50221').valid_encoding?.should be_true
-    str.force_encoding('Windows-1252').valid_encoding?.should be_true
-    str.force_encoding('Windows-1250').valid_encoding?.should be_true
-    str.force_encoding('Windows-1256').valid_encoding?.should be_true
-    str.force_encoding('Windows-1253').valid_encoding?.should be_true
-    str.force_encoding('Windows-1255').valid_encoding?.should be_true
-    str.force_encoding('Windows-1254').valid_encoding?.should be_true
-    str.force_encoding('TIS-620').valid_encoding?.should be_true
-    str.force_encoding('Windows-874').valid_encoding?.should be_true
-    str.force_encoding('Windows-1257').valid_encoding?.should be_true
-    str.force_encoding('Windows-31J').valid_encoding?.should be_false
-    str.force_encoding('MacJapanese').valid_encoding?.should be_false
-    str.force_encoding('UTF-7').valid_encoding?.should be_true
-    str.force_encoding('UTF8-MAC').valid_encoding?.should be_true
+    str = +"\xE6\x9D\x94"
+    str.force_encoding('BINARY').valid_encoding?.should == true
+    str.force_encoding('UTF-8').valid_encoding?.should == true
+    str.force_encoding('US-ASCII').valid_encoding?.should == false
+    str.force_encoding('Big5').valid_encoding?.should == false
+    str.force_encoding('CP949').valid_encoding?.should == false
+    str.force_encoding('Emacs-Mule').valid_encoding?.should == false
+    str.force_encoding('EUC-JP').valid_encoding?.should == false
+    str.force_encoding('EUC-KR').valid_encoding?.should == false
+    str.force_encoding('EUC-TW').valid_encoding?.should == false
+    str.force_encoding('GB18030').valid_encoding?.should == false
+    str.force_encoding('GBK').valid_encoding?.should == false
+    str.force_encoding('ISO-8859-1').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-2').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-3').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-4').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-5').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-6').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-7').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-8').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-9').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-10').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-11').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-13').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-14').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-15').valid_encoding?.should == true
+    str.force_encoding('ISO-8859-16').valid_encoding?.should == true
+    str.force_encoding('KOI8-R').valid_encoding?.should == true
+    str.force_encoding('KOI8-U').valid_encoding?.should == true
+    str.force_encoding('Shift_JIS').valid_encoding?.should == false
+    "\xD8\x00".dup.force_encoding('UTF-16BE').valid_encoding?.should == false
+    "\x00\xD8".dup.force_encoding('UTF-16LE').valid_encoding?.should == false
+    "\x04\x03\x02\x01".dup.force_encoding('UTF-32BE').valid_encoding?.should == false
+    "\x01\x02\x03\x04".dup.force_encoding('UTF-32LE').valid_encoding?.should == false
+    str.force_encoding('Windows-1251').valid_encoding?.should == true
+    str.force_encoding('IBM437').valid_encoding?.should == true
+    str.force_encoding('IBM737').valid_encoding?.should == true
+    str.force_encoding('IBM775').valid_encoding?.should == true
+    str.force_encoding('CP850').valid_encoding?.should == true
+    str.force_encoding('IBM852').valid_encoding?.should == true
+    str.force_encoding('CP852').valid_encoding?.should == true
+    str.force_encoding('IBM855').valid_encoding?.should == true
+    str.force_encoding('CP855').valid_encoding?.should == true
+    str.force_encoding('IBM857').valid_encoding?.should == true
+    str.force_encoding('IBM860').valid_encoding?.should == true
+    str.force_encoding('IBM861').valid_encoding?.should == true
+    str.force_encoding('IBM862').valid_encoding?.should == true
+    str.force_encoding('IBM863').valid_encoding?.should == true
+    str.force_encoding('IBM864').valid_encoding?.should == true
+    str.force_encoding('IBM865').valid_encoding?.should == true
+    str.force_encoding('IBM866').valid_encoding?.should == true
+    str.force_encoding('IBM869').valid_encoding?.should == true
+    str.force_encoding('Windows-1258').valid_encoding?.should == true
+    str.force_encoding('GB1988').valid_encoding?.should == true
+    str.force_encoding('macCentEuro').valid_encoding?.should == true
+    str.force_encoding('macCroatian').valid_encoding?.should == true
+    str.force_encoding('macCyrillic').valid_encoding?.should == true
+    str.force_encoding('macGreek').valid_encoding?.should == true
+    str.force_encoding('macIceland').valid_encoding?.should == true
+    str.force_encoding('macRoman').valid_encoding?.should == true
+    str.force_encoding('macRomania').valid_encoding?.should == true
+    str.force_encoding('macThai').valid_encoding?.should == true
+    str.force_encoding('macTurkish').valid_encoding?.should == true
+    str.force_encoding('macUkraine').valid_encoding?.should == true
+    str.force_encoding('stateless-ISO-2022-JP').valid_encoding?.should == false
+    str.force_encoding('eucJP-ms').valid_encoding?.should == false
+    str.force_encoding('CP51932').valid_encoding?.should == false
+    str.force_encoding('GB2312').valid_encoding?.should == false
+    str.force_encoding('GB12345').valid_encoding?.should == false
+    str.force_encoding('ISO-2022-JP').valid_encoding?.should == true
+    str.force_encoding('ISO-2022-JP-2').valid_encoding?.should == true
+    str.force_encoding('CP50221').valid_encoding?.should == true
+    str.force_encoding('Windows-1252').valid_encoding?.should == true
+    str.force_encoding('Windows-1250').valid_encoding?.should == true
+    str.force_encoding('Windows-1256').valid_encoding?.should == true
+    str.force_encoding('Windows-1253').valid_encoding?.should == true
+    str.force_encoding('Windows-1255').valid_encoding?.should == true
+    str.force_encoding('Windows-1254').valid_encoding?.should == true
+    str.force_encoding('TIS-620').valid_encoding?.should == true
+    str.force_encoding('Windows-874').valid_encoding?.should == true
+    str.force_encoding('Windows-1257').valid_encoding?.should == true
+    str.force_encoding('Windows-31J').valid_encoding?.should == false
+    str.force_encoding('MacJapanese').valid_encoding?.should == false
+    str.force_encoding('UTF-7').valid_encoding?.should == true
+    str.force_encoding('UTF8-MAC').valid_encoding?.should == true
+  end
+
+  it "returns true for IBM720 encoding self is valid in" do
+    str = +"\xE6\x9D\x94"
+    str.force_encoding('IBM720').valid_encoding?.should == true
+    str.force_encoding('CP720').valid_encoding?.should == true
   end
 
   it "returns false if self is valid in one encoding, but invalid in the one it's tagged with" do
-    str = "\u{8765}"
-    str.valid_encoding?.should be_true
-    str = str.force_encoding('ascii')
-    str.valid_encoding?.should be_false
+    str = +"\u{8765}"
+    str.valid_encoding?.should == true
+    str.force_encoding('ascii')
+    str.valid_encoding?.should == false
   end
 
   it "returns false if self contains a character invalid in the associated encoding" do
-    "abc#{[0x80].pack('C')}".force_encoding('ascii').valid_encoding?.should be_false
+    "abc#{[0x80].pack('C')}".dup.force_encoding('ascii').valid_encoding?.should == false
   end
 
   it "returns false if a valid String had an invalid character appended to it" do
-    str = "a"
-    str.valid_encoding?.should be_true
+    str = +"a"
+    str.valid_encoding?.should == true
     str << [0xDD].pack('C').force_encoding('utf-8')
-    str.valid_encoding?.should be_false
+    str.valid_encoding?.should == false
   end
 
   it "returns true if an invalid string is appended another invalid one but both make a valid string" do
     str = [0xD0].pack('C').force_encoding('utf-8')
-    str.valid_encoding?.should be_false
+    str.valid_encoding?.should == false
     str << [0xBF].pack('C').force_encoding('utf-8')
-    str.valid_encoding?.should be_true
+    str.valid_encoding?.should == true
   end
 end
diff --git a/spec/ruby/core/struct/clone_spec.rb b/spec/ruby/core/struct/clone_spec.rb
new file mode 100644
index 0000000000..40c4d52d57
--- /dev/null
+++ b/spec/ruby/core/struct/clone_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative 'shared/dup'
+
+describe "Struct-based class#clone" do
+  it_behaves_like :struct_dup, :clone
+end
diff --git a/spec/ruby/core/struct/constants_spec.rb b/spec/ruby/core/struct/constants_spec.rb
new file mode 100644
index 0000000000..7e8af1a211
--- /dev/null
+++ b/spec/ruby/core/struct/constants_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "Struct::Group" do
+  it "is no longer defined" do
+    Struct.should_not.const_defined?(:Group)
+  end
+end
+
+describe "Struct::Passwd" do
+  it "is no longer defined" do
+    Struct.should_not.const_defined?(:Passwd)
+  end
+end
diff --git a/spec/ruby/core/struct/deconstruct_keys_spec.rb b/spec/ruby/core/struct/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..590e1ab40b
--- /dev/null
+++ b/spec/ruby/core/struct/deconstruct_keys_spec.rb
@@ -0,0 +1,130 @@
+require_relative '../../spec_helper'
+
+describe "Struct#deconstruct_keys" do
+  it "returns a hash of attributes" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([:x, :y]).should == {x: 1, y: 2}
+  end
+
+  it "requires one argument" do
+    struct = Struct.new(:x)
+    obj = struct.new(1)
+
+    -> {
+      obj.deconstruct_keys
+    }.should.raise(ArgumentError, /wrong number of arguments \(given 0, expected 1\)/)
+  end
+
+  it "returns only specified keys" do
+    struct = Struct.new(:x, :y, :z)
+    s = struct.new(1, 2, 3)
+
+    s.deconstruct_keys([:x, :y]).should == {x: 1, y: 2}
+    s.deconstruct_keys([:x]    ).should == {x: 1}
+    s.deconstruct_keys([]      ).should == {}
+  end
+
+  it "accepts string attribute names" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys(['x', 'y']).should == {'x' => 1, 'y' => 2}
+  end
+
+  it "accepts argument position number as well but returns them as keys" do
+    struct = Struct.new(:x, :y, :z)
+    s = struct.new(10, 20, 30)
+
+    s.deconstruct_keys([0, 1, 2]).should == {0 => 10, 1 => 20, 2 => 30}
+    s.deconstruct_keys([0, 1]   ).should == {0 => 10, 1 => 20}
+    s.deconstruct_keys([0]      ).should == {0 => 10}
+    s.deconstruct_keys([-1]     ).should == {-1 => 30}
+  end
+
+  it "ignores incorrect position numbers" do
+    struct = Struct.new(:x, :y, :z)
+    s = struct.new(10, 20, 30)
+
+    s.deconstruct_keys([0, 3]).should == {0 => 10}
+  end
+
+  it "support mixing attribute names and argument position numbers" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([0, :x]).should == {0 => 1, :x => 1}
+  end
+
+  it "returns an empty hash when there are more keys than attributes" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([:x, :y, :a]).should == {}
+  end
+
+  it "returns at first not existing attribute name" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([:a, :x]).should == {}
+    s.deconstruct_keys([:x, :a]).should == {x: 1}
+  end
+
+  it "returns at first not existing argument position number" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([3, 0]).should == {}
+    s.deconstruct_keys([0, 3]).should == {0 => 1}
+  end
+
+  it "accepts nil argument and return all the attributes" do
+    struct = Struct.new(:x, :y)
+    obj = struct.new(1, 2)
+
+    obj.deconstruct_keys(nil).should == {x: 1, y: 2}
+  end
+
+  it "tries to convert a key with #to_int if index is not a String nor a Symbol, but responds to #to_int" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    key = mock("to_int")
+    key.should_receive(:to_int).and_return(1)
+
+    s.deconstruct_keys([key]).should == { key => 2 }
+  end
+
+  it "raises a TypeError if the conversion with #to_int does not return an Integer" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    key = mock("to_int")
+    key.should_receive(:to_int).and_return("not an Integer")
+
+    -> {
+      s.deconstruct_keys([key])
+    }.should raise_consistent_error(TypeError, /can't convert MockObject into Integer/)
+  end
+
+  it "raises TypeError if index is not a String, a Symbol and not convertible to Integer" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    -> {
+      s.deconstruct_keys([0, []])
+    }.should.raise(TypeError, "no implicit conversion of Array into Integer")
+  end
+
+  it "raise TypeError if passed anything except nil or array" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    -> { s.deconstruct_keys('x') }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys(1)   }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys(:x)  }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys({})  }.should.raise(TypeError, /expected Array or nil/)
+  end
+end
diff --git a/spec/ruby/core/struct/deconstruct_spec.rb b/spec/ruby/core/struct/deconstruct_spec.rb
new file mode 100644
index 0000000000..32d4f6bac4
--- /dev/null
+++ b/spec/ruby/core/struct/deconstruct_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+
+describe "Struct#deconstruct" do
+  it "returns an array of attribute values" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct.should == [1, 2]
+  end
+end
diff --git a/spec/ruby/core/struct/dig_spec.rb b/spec/ruby/core/struct/dig_spec.rb
index 4e39e5a4ef..52e4d1dd9a 100644
--- a/spec/ruby/core/struct/dig_spec.rb
+++ b/spec/ruby/core/struct/dig_spec.rb
@@ -10,6 +10,16 @@ describe "Struct#dig" do
     @instance.dig(:a, :a).should == { b: [1, 2, 3] }
   end
 
+  it "accepts String keys" do
+    @instance.dig('a', 'a').should == { b: [1, 2, 3] }
+  end
+
+  it "returns the value by the index" do
+    instance = Struct.new(:a, :b).new(:one, :two)
+    instance.dig(0).should == :one
+    instance.dig(1).should == :two
+  end
+
   it "returns the nested value specified if the sequence includes an index" do
     @instance.dig(:a, :a, :b, 0).should == 1
   end
@@ -22,11 +32,11 @@ describe "Struct#dig" do
     instance = @klass.new(1)
     -> {
       instance.dig(:a, 3)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if no arguments provided" do
-    -> { @instance.dig }.should raise_error(ArgumentError)
+    -> { @instance.dig }.should.raise(ArgumentError)
   end
 
   it "calls #dig on any intermediate step with the rest of the sequence as arguments" do
diff --git a/spec/ruby/core/struct/dup_spec.rb b/spec/ruby/core/struct/dup_spec.rb
index cb54b7ceee..8b50c39014 100644
--- a/spec/ruby/core/struct/dup_spec.rb
+++ b/spec/ruby/core/struct/dup_spec.rb
@@ -1,8 +1,11 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative 'shared/dup'
 
 describe "Struct-based class#dup" do
 
+  it_behaves_like :struct_dup, :dup
+
   # From https://github.com/jruby/jruby/issues/3686
   it "retains an included module in the ancestor chain for the struct's singleton class" do
     klass = Struct.new(:foo)
diff --git a/spec/ruby/core/struct/each_pair_spec.rb b/spec/ruby/core/struct/each_pair_spec.rb
index 1230ca9026..db146c81e9 100644
--- a/spec/ruby/core/struct/each_pair_spec.rb
+++ b/spec/ruby/core/struct/each_pair_spec.rb
@@ -21,11 +21,11 @@ describe "Struct#each_pair" do
   end
 
   it "returns self if passed a block" do
-    @car.each_pair {}.should equal(@car)
+    @car.each_pair {}.should.equal?(@car)
   end
 
   it "returns an Enumerator if not passed a block" do
-    @car.each_pair.should be_an_instance_of(Enumerator)
+    @car.each_pair.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :struct_accessor, :each_pair
diff --git a/spec/ruby/core/struct/each_spec.rb b/spec/ruby/core/struct/each_spec.rb
index 41c0fbd4d0..4fbdfee02a 100644
--- a/spec/ruby/core/struct/each_spec.rb
+++ b/spec/ruby/core/struct/each_spec.rb
@@ -19,7 +19,7 @@ describe "Struct#each" do
 
   it "returns an Enumerator if not passed a block" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    car.each.should be_an_instance_of(Enumerator)
+    car.each.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :struct_accessor, :each
diff --git a/spec/ruby/core/struct/element_reference_spec.rb b/spec/ruby/core/struct/element_reference_spec.rb
index 0f6d547f66..b94f3aae8c 100644
--- a/spec/ruby/core/struct/element_reference_spec.rb
+++ b/spec/ruby/core/struct/element_reference_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Struct[]" do
   it "is a synonym for new" do
-    StructClasses::Ruby['2.0', 'i686'].should be_kind_of(StructClasses::Ruby)
+    StructClasses::Ruby['2.0', 'i686'].should.is_a?(StructClasses::Ruby)
   end
 end
 
@@ -26,20 +26,20 @@ describe "Struct#[]" do
 
   it "fails when it does not know about the requested attribute" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[3]        }.should raise_error(IndexError)
-    -> { car[-4]       }.should raise_error(IndexError)
-    -> { car[:body]    }.should raise_error(NameError)
-    -> { car['wheels'] }.should raise_error(NameError)
+    -> { car[3]        }.should.raise(IndexError)
+    -> { car[-4]       }.should.raise(IndexError)
+    -> { car[:body]    }.should.raise(NameError)
+    -> { car['wheels'] }.should.raise(NameError)
   end
 
   it "fails if passed too many arguments" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[:make, :model] }.should raise_error(ArgumentError)
+    -> { car[:make, :model] }.should.raise(ArgumentError)
   end
 
   it "fails if not passed a string, symbol, or integer" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[Object.new] }.should raise_error(TypeError)
+    -> { car[Object.new] }.should.raise(TypeError)
   end
 
   it "returns attribute names that contain hyphens" do
diff --git a/spec/ruby/core/struct/element_set_spec.rb b/spec/ruby/core/struct/element_set_spec.rb
index 6ba7b081a9..e5438ca09a 100644
--- a/spec/ruby/core/struct/element_set_spec.rb
+++ b/spec/ruby/core/struct/element_set_spec.rb
@@ -21,9 +21,16 @@ describe "Struct#[]=" do
   it "fails when trying to assign attributes which don't exist" do
     car = StructClasses::Car.new('Ford', 'Ranger')
 
-    -> { car[:something] = true }.should raise_error(NameError)
-    -> { car[3] = true          }.should raise_error(IndexError)
-    -> { car[-4] = true         }.should raise_error(IndexError)
-    -> { car[Object.new] = true }.should raise_error(TypeError)
+    -> { car[:something] = true }.should.raise(NameError)
+    -> { car[3] = true          }.should.raise(IndexError)
+    -> { car[-4] = true         }.should.raise(IndexError)
+    -> { car[Object.new] = true }.should.raise(TypeError)
+  end
+
+  it "raises a FrozenError on a frozen struct" do
+    car = StructClasses::Car.new('Ford', 'Ranger')
+    car.freeze
+
+    -> { car[:model] = 'Escape' }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/struct/eql_spec.rb b/spec/ruby/core/struct/eql_spec.rb
index c864b2b943..327c927278 100644
--- a/spec/ruby/core/struct/eql_spec.rb
+++ b/spec/ruby/core/struct/eql_spec.rb
@@ -8,6 +8,6 @@ describe "Struct#eql?" do
   it "returns false if any corresponding elements are not #eql?" do
     car = StructClasses::Car.new("Honda", "Accord", 1998)
     similar_car = StructClasses::Car.new("Honda", "Accord", 1998.0)
-    car.should_not eql(similar_car)
+    car.should_not.eql?(similar_car)
   end
 end
diff --git a/spec/ruby/core/struct/filter_spec.rb b/spec/ruby/core/struct/filter_spec.rb
index 1105ed064a..0ccd8ad6b2 100644
--- a/spec/ruby/core/struct/filter_spec.rb
+++ b/spec/ruby/core/struct/filter_spec.rb
@@ -3,10 +3,8 @@ require_relative 'shared/select'
 require_relative 'shared/accessor'
 require_relative '../enumerable/shared/enumeratorized'
 
-ruby_version_is "2.6" do
-  describe "Struct#filter" do
-    it_behaves_like :struct_select, :filter
-    it_behaves_like :struct_accessor, :filter
-    it_behaves_like :enumeratorized_with_origin_size, :filter, Struct.new(:foo).new
-  end
+describe "Struct#filter" do
+  it_behaves_like :struct_select, :filter
+  it_behaves_like :struct_accessor, :filter
+  it_behaves_like :enumeratorized_with_origin_size, :filter, Struct.new(:foo).new
 end
diff --git a/spec/ruby/core/struct/fixtures/classes.rb b/spec/ruby/core/struct/fixtures/classes.rb
index 6d620f9060..675d403abd 100644
--- a/spec/ruby/core/struct/fixtures/classes.rb
+++ b/spec/ruby/core/struct/fixtures/classes.rb
@@ -3,6 +3,7 @@ module StructClasses
   class Apple < Struct; end
 
   Ruby = Struct.new(:version, :platform)
+  Single = Struct.new(:value)
 
   Car = Struct.new(:make, :model, :year)
 
@@ -13,6 +14,12 @@ module StructClasses
     end
   end
 
+  class StructWithOverriddenName < Struct.new(:a)
+    def self.name
+      "A"
+    end
+  end
+
   class SubclassX < Struct
   end
 
@@ -23,4 +30,6 @@ module StructClasses
       super
     end
   end
+
+  class StructSubclass < Struct; end
 end
diff --git a/spec/ruby/core/struct/hash_spec.rb b/spec/ruby/core/struct/hash_spec.rb
index 71e8ccbd3a..750387b326 100644
--- a/spec/ruby/core/struct/hash_spec.rb
+++ b/spec/ruby/core/struct/hash_spec.rb
@@ -4,21 +4,35 @@ require_relative 'shared/accessor'
 
 describe "Struct#hash" do
 
-  it "returns the same fixnum for structs with the same content" do
+  it "returns the same integer for structs with the same content" do
     [StructClasses::Ruby.new("1.8.6", "PPC"),
      StructClasses::Car.new("Hugo", "Foo", "1972")].each do |stc|
       stc.hash.should == stc.dup.hash
-      stc.hash.should be_kind_of(Fixnum)
+      stc.hash.should.is_a?(Integer)
     end
   end
 
   it "returns the same value if structs are #eql?" do
     car = StructClasses::Car.new("Honda", "Accord", "1998")
     similar_car = StructClasses::Car.new("Honda", "Accord", "1998")
-    car.should eql(similar_car)
+    car.should.eql?(similar_car)
     car.hash.should == similar_car.hash
   end
 
+  it "returns different hashes for structs with different values" do
+    s1 = StructClasses::Ruby.new('2.7.0', 'linux')
+    s2 = StructClasses::Ruby.new('2.7.0', 'macos')
+    s1.hash.should_not == s2.hash
+  end
+
+  it "returns different hashes for structs with different values when using keyword_init: true" do
+    key = :"1 non symbol member"
+    struct_class = Struct.new(key, keyword_init: true)
+    t1 = struct_class.new(key => 1)
+    t2 = struct_class.new(key => 2)
+    t1.hash.should_not == t2.hash
+  end
+
   it "allows for overriding methods in an included module" do
     mod = Module.new do
       def hash
@@ -42,5 +56,9 @@ describe "Struct#hash" do
     # See the Struct#eql? specs
   end
 
+  it "returns different hashes for different struct classes" do
+    Struct.new(:x).new(1).hash.should != Struct.new(:y).new(1).hash
+  end
+
   it_behaves_like :struct_accessor, :hash
 end
diff --git a/spec/ruby/core/struct/initialize_spec.rb b/spec/ruby/core/struct/initialize_spec.rb
index e82289071a..c824f52e13 100644
--- a/spec/ruby/core/struct/initialize_spec.rb
+++ b/spec/ruby/core/struct/initialize_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Struct#initialize" do
 
   it "is private" do
-    StructClasses::Car.should have_private_instance_method(:initialize)
+    StructClasses::Car.private_instance_methods(true).should.include?(:initialize)
   end
 
   it 'allows valid Ruby method names for members' do
@@ -40,4 +40,35 @@ describe "Struct#initialize" do
   it "can be overridden" do
     StructClasses::SubclassX.new(:y).new.key.should == :value
   end
+
+  it "can be initialized with keyword arguments" do
+    positional_args = StructClasses::Ruby.new("3.2", "OS")
+    keyword_args = StructClasses::Ruby.new(version: "3.2", platform: "OS")
+
+    positional_args.version.should == keyword_args.version
+    positional_args.platform.should == keyword_args.platform
+  end
+
+  it "accepts positional arguments with empty keyword arguments" do
+    data = StructClasses::Single.new(42, **{})
+
+    data.value.should == 42
+
+    data = StructClasses::Ruby.new("3.2", "OS", **{})
+
+    data.version.should == "3.2"
+    data.platform.should == "OS"
+  end
+
+  it "can be called via delegated ... from a prepended module" do
+    wrapper = Module.new do
+      def initialize(...)
+        super(...)
+      end
+    end
+
+    klass = Class.new(Struct.new(:a)) { prepend wrapper }
+    s = klass.new("x")
+    s.a.should == "x"
+  end
 end
diff --git a/spec/ruby/core/struct/inspect_spec.rb b/spec/ruby/core/struct/inspect_spec.rb
index 83e13597ba..657b06abc1 100644
--- a/spec/ruby/core/struct/inspect_spec.rb
+++ b/spec/ruby/core/struct/inspect_spec.rb
@@ -3,10 +3,5 @@ require_relative 'fixtures/classes'
 require_relative 'shared/inspect'
 
 describe "Struct#inspect" do
-  it "returns a string representation showing members and values" do
-    car = StructClasses::Car.new('Ford', 'Ranger')
-    car.inspect.should == '#<struct StructClasses::Car make="Ford", model="Ranger", year=nil>'
-  end
-
   it_behaves_like :struct_inspect, :inspect
 end
diff --git a/spec/ruby/core/struct/instance_variable_get_spec.rb b/spec/ruby/core/struct/instance_variable_get_spec.rb
new file mode 100644
index 0000000000..e3555cd246
--- /dev/null
+++ b/spec/ruby/core/struct/instance_variable_get_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Struct#instance_variable_get" do
+  it "returns nil for attributes" do
+    car = StructClasses::Car.new("Hugo", "Foo", "1972")
+    car.instance_variable_get(:@make).should == nil
+  end
+
+  it "returns a user value for variables with the same name as attributes" do
+    car = StructClasses::Car.new("Hugo", "Foo", "1972")
+    car.instance_variable_set :@make, "explicit"
+    car.instance_variable_get(:@make).should == "explicit"
+    car.make.should == "Hugo"
+  end
+end
diff --git a/spec/ruby/core/struct/keyword_init_spec.rb b/spec/ruby/core/struct/keyword_init_spec.rb
new file mode 100644
index 0000000000..42fcd3cc29
--- /dev/null
+++ b/spec/ruby/core/struct/keyword_init_spec.rb
@@ -0,0 +1,45 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# See https://bugs.ruby-lang.org/issues/18008
+describe "StructClass#keyword_init?" do
+  it "returns true for a struct that accepts keyword arguments to initialize" do
+    struct = Struct.new(:arg, keyword_init: true)
+    struct.keyword_init?.should == true
+  end
+
+  it "returns false for a struct that does not accept keyword arguments to initialize" do
+    struct = Struct.new(:arg, keyword_init: false)
+    struct.keyword_init?.should == false
+  end
+
+  it "returns nil for a struct that did not explicitly specify keyword_init" do
+    struct = Struct.new(:arg)
+    struct.keyword_init?.should == nil
+  end
+
+  it "returns nil for a struct that does specify keyword_init to be nil" do
+    struct = Struct.new(:arg, keyword_init: nil)
+    struct.keyword_init?.should == nil
+  end
+
+  it "returns true for any truthy value, not just for true" do
+    struct = Struct.new(:arg, keyword_init: 1)
+    struct.keyword_init?.should == true
+
+    struct = Struct.new(:arg, keyword_init: "")
+    struct.keyword_init?.should == true
+
+    struct = Struct.new(:arg, keyword_init: [])
+    struct.keyword_init?.should == true
+
+    struct = Struct.new(:arg, keyword_init: {})
+    struct.keyword_init?.should == true
+  end
+
+  context "class inheriting Struct" do
+    it "isn't available in a subclass" do
+      StructClasses::StructSubclass.should_not.respond_to?(:keyword_init?)
+    end
+  end
+end
diff --git a/spec/ruby/core/struct/members_spec.rb b/spec/ruby/core/struct/members_spec.rb
index 1f2ff950d9..1ff7b9387a 100644
--- a/spec/ruby/core/struct/members_spec.rb
+++ b/spec/ruby/core/struct/members_spec.rb
@@ -11,3 +11,15 @@ describe "Struct#members" do
 
   it_behaves_like :struct_accessor, :members
 end
+
+describe "StructClass#members" do
+  it "returns an array of attribute names" do
+    StructClasses::Car.members.should == [:make, :model, :year]
+  end
+
+  context "class inheriting Struct" do
+    it "isn't available in a subclass" do
+      StructClasses::StructSubclass.should_not.respond_to?(:members)
+    end
+  end
+end
diff --git a/spec/ruby/core/struct/new_spec.rb b/spec/ruby/core/struct/new_spec.rb
index f888106950..b3ece2efed 100644
--- a/spec/ruby/core/struct/new_spec.rb
+++ b/spec/ruby/core/struct/new_spec.rb
@@ -6,6 +6,8 @@ describe "Struct.new" do
     struct = Struct.new('Animal', :name, :legs, :eyeballs)
     struct.should == Struct::Animal
     struct.name.should == "Struct::Animal"
+  ensure
+    Struct.send(:remove_const, :Animal)
   end
 
   it "overwrites previously defined constants with string as first argument" do
@@ -15,10 +17,12 @@ describe "Struct.new" do
     second = nil
     -> {
       second = Struct.new('Person', :hair, :sex)
-    }.should complain(/redefining constant/)
+    }.should complain(/constant/)
     second.should == Struct::Person
 
     first.members.should_not == second.members
+  ensure
+    Struct.send(:remove_const, :Person)
   end
 
   it "calls to_str on its first argument (constant name)" do
@@ -27,62 +31,71 @@ describe "Struct.new" do
     struct = Struct.new(obj)
     struct.should == Struct::Foo
     struct.name.should == "Struct::Foo"
+  ensure
+    Struct.send(:remove_const, :Foo)
   end
 
   it "creates a new anonymous class with nil first argument" do
     struct = Struct.new(nil, :foo)
     struct.new("bar").foo.should == "bar"
-    struct.should be_kind_of(Class)
-    struct.name.should be_nil
+    struct.should.is_a?(Class)
+    struct.name.should == nil
   end
 
   it "creates a new anonymous class with symbol arguments" do
     struct = Struct.new(:make, :model)
-    struct.should be_kind_of(Class)
+    struct.should.is_a?(Class)
     struct.name.should == nil
   end
 
   it "does not create a constant with symbol as first argument" do
     Struct.new(:Animal2, :name, :legs, :eyeballs)
-    Struct.const_defined?("Animal2").should be_false
+    Struct.const_defined?("Animal2").should == false
   end
 
+  it "allows non-ASCII member name" do
+    name = "r\xe9sum\xe9".dup.force_encoding(Encoding::ISO_8859_1).to_sym
+    struct = Struct.new(name)
+    struct.new("foo").send(name).should == "foo"
+  end
 
   it "fails with invalid constant name as first argument" do
-    -> { Struct.new('animal', :name, :legs, :eyeballs) }.should raise_error(NameError)
+    -> { Struct.new('animal', :name, :legs, :eyeballs) }.should.raise(NameError)
   end
 
   it "raises a TypeError if object doesn't respond to to_sym" do
-    -> { Struct.new(:animal, mock('giraffe'))      }.should raise_error(TypeError)
-    -> { Struct.new(:animal, 1.0)                  }.should raise_error(TypeError)
-    -> { Struct.new(:animal, Time.now)             }.should raise_error(TypeError)
-    -> { Struct.new(:animal, Class)                }.should raise_error(TypeError)
-    -> { Struct.new(:animal, nil)                  }.should raise_error(TypeError)
-    -> { Struct.new(:animal, true)                 }.should raise_error(TypeError)
-    -> { Struct.new(:animal, ['chris', 'evan'])    }.should raise_error(TypeError)
-  end
-
-  ruby_version_is ""..."2.5" do
-    it "raises a TypeError if an argument is a Hash" do
-      -> { Struct.new(:animal, { name: 'chris' }) }.should raise_error(TypeError)
-    end
+    -> { Struct.new(:animal, mock('giraffe'))      }.should.raise(TypeError)
+    -> { Struct.new(:animal, 1.0)                  }.should.raise(TypeError)
+    -> { Struct.new(:animal, Time.now)             }.should.raise(TypeError)
+    -> { Struct.new(:animal, Class)                }.should.raise(TypeError)
+    -> { Struct.new(:animal, nil)                  }.should.raise(TypeError)
+    -> { Struct.new(:animal, true)                 }.should.raise(TypeError)
+    -> { Struct.new(:animal, ['chris', 'evan'])    }.should.raise(TypeError)
   end
 
-  ruby_version_is "2.5" do
-    it "raises a ArgumentError if passed a Hash with an unknown key" do
-      -> { Struct.new(:animal, { name: 'chris' }) }.should raise_error(ArgumentError)
-    end
+  it "raises a TypeError if passed a Hash with an unknown key" do
+    -> { Struct.new(:animal, { name: 'chris' }) }.should.raise(TypeError)
+  end
+
+  it "works when not provided any arguments" do
+    c = Struct.new
+    c.should.is_a?(Class)
+    c.superclass.should == Struct
+  end
+
+  it "raises ArgumentError when there is a duplicate member" do
+    -> { Struct.new(:foo, :foo) }.should.raise(ArgumentError, "duplicate member: foo")
   end
 
   it "raises a TypeError if object is not a Symbol" do
     obj = mock(':ruby')
     def obj.to_sym() :ruby end
-    -> { Struct.new(:animal, obj) }.should raise_error(TypeError)
+    -> { Struct.new(:animal, obj) }.should.raise(TypeError)
   end
 
   it "processes passed block with instance_eval" do
     klass = Struct.new(:something) { @something_else = 'something else entirely!' }
-    klass.instance_variables.should include(:@something_else)
+    klass.instance_variables.should.include?(:@something_else)
   end
 
   context "with a block" do
@@ -103,7 +116,7 @@ describe "Struct.new" do
       klass = Struct.new(:attr) do |block_parameter|
         given = block_parameter
       end
-      klass.should equal(given)
+      klass.should.equal?(given)
     end
   end
 
@@ -111,6 +124,8 @@ describe "Struct.new" do
     it "creates a constant in subclass' namespace" do
       struct = StructClasses::Apple.new('Computer', :size)
       struct.should == StructClasses::Apple::Computer
+    ensure
+      StructClasses::Apple.send(:remove_const, :Computer)
     end
 
     it "creates an instance" do
@@ -118,77 +133,123 @@ describe "Struct.new" do
     end
 
     it "creates reader methods" do
-      StructClasses::Ruby.new.should have_method(:version)
-      StructClasses::Ruby.new.should have_method(:platform)
+      StructClasses::Ruby.new.should.respond_to?(:version)
+      StructClasses::Ruby.new.should.respond_to?(:platform)
     end
 
     it "creates writer methods" do
-      StructClasses::Ruby.new.should have_method(:version=)
-      StructClasses::Ruby.new.should have_method(:platform=)
+      StructClasses::Ruby.new.should.respond_to?(:version=)
+      StructClasses::Ruby.new.should.respond_to?(:platform=)
     end
 
     it "fails with too many arguments" do
-      -> { StructClasses::Ruby.new('2.0', 'i686', true) }.should raise_error(ArgumentError)
+      -> { StructClasses::Ruby.new('2.0', 'i686', true) }.should.raise(ArgumentError)
     end
 
-    it "passes a hash as a normal argument" do
+    it "accepts keyword arguments to initialize" do
       type = Struct.new(:args)
 
-      obj = type.new(keyword: :arg)
-      obj2 = type.new(*[{keyword: :arg}])
+      obj = type.new(args: 42)
+      obj2 = type.new(42)
 
       obj.should == obj2
-      obj.args.should == {keyword: :arg}
-      obj2.args.should == {keyword: :arg}
+      obj.args.should == 42
+      obj2.args.should == 42
     end
-  end
 
-  ruby_version_is "2.5" do
-    context "keyword_init: true option" do
-      before :all do
-        @struct_with_kwa = Struct.new(:name, :legs, keyword_init: true)
-        @struct_without_kwa = Struct.new(:name, :legs, keyword_init: false)
+    context "given positional and keyword arguments" do
+      it "treats keyword arguments as a positional parameter" do
+        type = Struct.new(:a, :b)
+        s = type.new("a", b: "b")
+        s.a.should == "a"
+        s.b.should == {b: "b"}
+
+        type = Struct.new(:a, :b, :c)
+        s = type.new("a", b: "b", c: "c")
+        s.a.should == "a"
+        s.b.should == {b: "b", c: "c"}
+        s.c.should == nil
       end
 
-      it "creates a class that accepts keyword arguments to initialize" do
-        obj = @struct_with_kwa.new(name: "elefant", legs: 4)
-        obj.name.should == "elefant"
-        obj.legs.should == 4
+      it "ignores empty keyword arguments" do
+        type = Struct.new(:a, :b)
+        h = {}
+        s = type.new("a", **h)
+
+        s.a.should == "a"
+        s.b.should == nil
       end
 
-      describe "new class instantiation" do
-        it "accepts arguments as hash as well" do
-          obj = @struct_with_kwa.new({name: "elefant", legs: 4})
-          obj.name.should == "elefant"
-          obj.legs.should == 4
-        end
+      it "raises ArgumentError when all struct attribute values are specified" do
+        type = Struct.new(:a, :b)
+        -> { type.new("a", "b", c: "c") }.should.raise(ArgumentError, "struct size differs")
+      end
+    end
+  end
 
-        it "raises ArgumentError when passed not declared keyword argument" do
-          -> {
-            @struct_with_kwa.new(name: "elefant", legs: 4, foo: "bar")
-          }.should raise_error(ArgumentError, /unknown keywords: foo/)
-        end
+  context "keyword_init: true option" do
+    before :all do
+      @struct_with_kwa = Struct.new(:name, :legs, keyword_init: true)
+    end
 
-        it "raises ArgumentError when passed a list of arguments" do
-          -> {
-            @struct_with_kwa.new("elefant", 4)
-          }.should raise_error(ArgumentError, /wrong number of arguments/)
-        end
+    it "creates a class that accepts keyword arguments to initialize" do
+      obj = @struct_with_kwa.new(name: "elefant", legs: 4)
+      obj.name.should == "elefant"
+      obj.legs.should == 4
+    end
 
-        it "raises ArgumentError when passed a single non-hash argument" do
-          -> {
-            @struct_with_kwa.new("elefant")
-          }.should raise_error(ArgumentError, /wrong number of arguments/)
-        end
-      end
+    it "raises when there is a duplicate member" do
+      -> { Struct.new(:foo, :foo, keyword_init: true) }.should.raise(ArgumentError, "duplicate member: foo")
     end
 
-    context "keyword_init: false option" do
-      it "behaves like it does without :keyword_init option" do
-        obj = @struct_without_kwa.new("elefant", 4)
+    describe "new class instantiation" do
+      it "accepts arguments as hash as well" do
+        obj = @struct_with_kwa.new({name: "elefant", legs: 4})
         obj.name.should == "elefant"
         obj.legs.should == 4
       end
+
+      it "allows missing arguments" do
+        obj = @struct_with_kwa.new(name: "elefant")
+        obj.name.should == "elefant"
+        obj.legs.should == nil
+      end
+
+      it "allows no arguments" do
+        obj = @struct_with_kwa.new
+        obj.name.should == nil
+        obj.legs.should == nil
+      end
+
+      it "raises ArgumentError when passed not declared keyword argument" do
+        -> {
+          @struct_with_kwa.new(name: "elefant", legs: 4, foo: "bar")
+        }.should.raise(ArgumentError, /unknown keywords: foo/)
+      end
+
+      it "raises ArgumentError when passed a list of arguments" do
+        -> {
+          @struct_with_kwa.new("elefant", 4)
+        }.should.raise(ArgumentError, /wrong number of arguments/)
+      end
+
+      it "raises ArgumentError when passed a single non-hash argument" do
+        -> {
+          @struct_with_kwa.new("elefant")
+        }.should.raise(ArgumentError, /wrong number of arguments/)
+      end
+    end
+  end
+
+  context "keyword_init: false option" do
+    before :all do
+      @struct_without_kwa = Struct.new(:name, :legs, keyword_init: false)
+    end
+
+    it "behaves like it does without :keyword_init option" do
+      obj = @struct_without_kwa.new("elefant", 4)
+      obj.name.should == "elefant"
+      obj.legs.should == 4
     end
   end
 end
diff --git a/spec/ruby/core/struct/shared/dup.rb b/spec/ruby/core/struct/shared/dup.rb
new file mode 100644
index 0000000000..994f3f443e
--- /dev/null
+++ b/spec/ruby/core/struct/shared/dup.rb
@@ -0,0 +1,9 @@
+describe :struct_dup, shared: true do
+  it "duplicates members" do
+    klass = Struct.new(:foo, :bar)
+    instance = klass.new(14, 2)
+    duped = instance.send(@method)
+    duped.foo.should == 14
+    duped.bar.should == 2
+  end
+end
diff --git a/spec/ruby/core/struct/shared/inspect.rb b/spec/ruby/core/struct/shared/inspect.rb
index 90594a5452..1a0fb6a6b2 100644
--- a/spec/ruby/core/struct/shared/inspect.rb
+++ b/spec/ruby/core/struct/shared/inspect.rb
@@ -1,5 +1,40 @@
 describe :struct_inspect, shared: true do
+  it "returns a string representation showing members and values" do
+    car = StructClasses::Car.new('Ford', 'Ranger')
+    car.send(@method).should == '#<struct StructClasses::Car make="Ford", model="Ranger", year=nil>'
+  end
+
   it "returns a string representation without the class name for anonymous structs" do
     Struct.new(:a).new("").send(@method).should == '#<struct a="">'
   end
+
+  it "returns a string representation without the class name for structs nested in anonymous classes" do
+    c = Class.new
+    c.class_eval <<~DOC
+      class Foo < Struct.new(:a); end
+    DOC
+
+    c::Foo.new("").send(@method).should == '#<struct a="">'
+  end
+
+  it "returns a string representation without the class name for structs nested in anonymous modules" do
+    m = Module.new
+    m.module_eval <<~DOC
+      class Foo < Struct.new(:a); end
+    DOC
+
+    m::Foo.new("").send(@method).should == '#<struct a="">'
+  end
+
+  it "does not call #name method" do
+    struct = StructClasses::StructWithOverriddenName.new("")
+    struct.send(@method).should == '#<struct StructClasses::StructWithOverriddenName a="">'
+  end
+
+  it "does not call #name method when struct is anonymous" do
+    struct = Struct.new(:a)
+    def struct.name; "A"; end
+
+    struct.new("").send(@method).should == '#<struct a="">'
+  end
 end
diff --git a/spec/ruby/core/struct/shared/select.rb b/spec/ruby/core/struct/shared/select.rb
index 35abee461b..dfa1a809fe 100644
--- a/spec/ruby/core/struct/shared/select.rb
+++ b/spec/ruby/core/struct/shared/select.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe :struct_select, shared: true do
   it "raises an ArgumentError if given any non-block arguments" do
     struct = StructClasses::Car.new
-    -> { struct.send(@method, 1) { } }.should raise_error(ArgumentError)
+    -> { struct.send(@method, 1) { } }.should.raise(ArgumentError)
   end
 
   it "returns a new array of elements for which block is true" do
@@ -14,13 +14,13 @@ describe :struct_select, shared: true do
 
   it "returns an instance of Array" do
     struct = StructClasses::Car.new("Ford", "Escort", "1995")
-    struct.send(@method) { true }.should be_an_instance_of(Array)
+    struct.send(@method) { true }.should.instance_of?(Array)
   end
 
   describe "without block" do
     it "returns an instance of Enumerator" do
       struct = Struct.new(:foo).new
-      struct.send(@method).should be_an_instance_of(Enumerator)
+      struct.send(@method).should.instance_of?(Enumerator)
     end
   end
 end
diff --git a/spec/ruby/core/struct/struct_spec.rb b/spec/ruby/core/struct/struct_spec.rb
index 8817dc1a58..9fab9c0629 100644
--- a/spec/ruby/core/struct/struct_spec.rb
+++ b/spec/ruby/core/struct/struct_spec.rb
@@ -21,7 +21,7 @@ describe "Struct anonymous class instance methods" do
 
   it "reader method should not interfere with undefined methods" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car.something_weird }.should raise_error(NoMethodError)
+    -> { car.something_weird }.should.raise(NoMethodError)
   end
 
   it "writer method be a synonym for []=" do
@@ -33,6 +33,13 @@ describe "Struct anonymous class instance methods" do
     car['model'].should == 'F150'
     car[1].should == 'F150'
   end
+
+  it "writer methods raise a FrozenError on a frozen struct" do
+    car = StructClasses::Car.new('Ford', 'Ranger')
+    car.freeze
+
+    -> { car.model = 'Escape' }.should.raise(FrozenError)
+  end
 end
 
 describe "Struct subclasses" do
diff --git a/spec/ruby/core/struct/to_h_spec.rb b/spec/ruby/core/struct/to_h_spec.rb
index b5f4e40701..e0846ef268 100644
--- a/spec/ruby/core/struct/to_h_spec.rb
+++ b/spec/ruby/core/struct/to_h_spec.rb
@@ -13,46 +13,56 @@ describe "Struct#to_h" do
     car.make.should == 'Ford'
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        car = StructClasses::Car.new('Ford', 'Ranger')
-
-        h = car.to_h { |k, v| [k.to_s, "#{v}".downcase] }
-        h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          StructClasses::Car.new.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          StructClasses::Car.new.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        StructClasses::Car.new.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          StructClasses::Car.new.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      car = StructClasses::Car.new('Ford', 'Ranger')
+
+      h = car.to_h { |k, v| [k.to_s, "#{v}".downcase] }
+      h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
+    end
+
+    it "passes to a block each pair's key and value as separate arguments" do
+      s = StructClasses::Ruby.new('3.2.4', 'macos')
+
+      ScratchPad.record []
+      s.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [[:platform, 'macos'], [:version, '3.2.4']]
+
+      ScratchPad.record []
+      s.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[:platform, 'macos'], [:version, '3.2.4']]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        StructClasses::Car.new.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        StructClasses::Car.new.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      StructClasses::Car.new.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        StructClasses::Car.new.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/struct/values_at_spec.rb b/spec/ruby/core/struct/values_at_spec.rb
index 7e517cdb4b..6aac5d96b3 100644
--- a/spec/ruby/core/struct/values_at_spec.rb
+++ b/spec/ruby/core/struct/values_at_spec.rb
@@ -1,16 +1,59 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
+# Should be synchronized with core/array/values_at_spec.rb
 describe "Struct#values_at" do
-  it "returns an array of values" do
+  before do
     clazz = Struct.new(:name, :director, :year)
-    movie = clazz.new('Sympathy for Mr. Vengence', 'Chan-wook Park', 2002)
-    movie.values_at(0, 1).should == ['Sympathy for Mr. Vengence', 'Chan-wook Park']
-    movie.values_at(0..2).should == ['Sympathy for Mr. Vengence', 'Chan-wook Park', 2002]
+    @movie = clazz.new('Sympathy for Mr. Vengeance', 'Chan-wook Park', 2002)
+  end
+
+  context "when passed a list of Integers" do
+    it "returns an array containing each value given by one of integers" do
+      @movie.values_at(0, 1).should == ['Sympathy for Mr. Vengeance', 'Chan-wook Park']
+    end
+
+    it "raises IndexError if any of integers is out of range" do
+      -> { @movie.values_at(3) }.should.raise(IndexError, "offset 3 too large for struct(size:3)")
+      -> { @movie.values_at(-4) }.should.raise(IndexError, "offset -4 too small for struct(size:3)")
+    end
+  end
+
+  context "when passed an integer Range" do
+    it "returns an array containing each value given by the elements of the range" do
+      @movie.values_at(0..2).should == ['Sympathy for Mr. Vengeance', 'Chan-wook Park', 2002]
+    end
+
+    it "fills with nil values for range elements larger than the structure" do
+      @movie.values_at(0..3).should == ['Sympathy for Mr. Vengeance', 'Chan-wook Park', 2002, nil]
+    end
+
+    it "raises RangeError if any element of the range is negative and out of range" do
+      -> { @movie.values_at(-4..3) }.should.raise(RangeError, "-4..3 out of range")
+    end
+
+    it "supports endless Range" do
+      @movie.values_at(0..).should == ["Sympathy for Mr. Vengeance", "Chan-wook Park", 2002]
+    end
+
+    it "supports beginningless Range" do
+      @movie.values_at(..2).should == ["Sympathy for Mr. Vengeance", "Chan-wook Park", 2002]
+    end
+  end
+
+  it "supports multiple integer Ranges" do
+    @movie.values_at(0..2, 1..2).should == ['Sympathy for Mr. Vengeance', 'Chan-wook Park', 2002, 'Chan-wook Park', 2002]
+  end
+
+  it "supports mixing integer Ranges and Integers" do
+    @movie.values_at(0..2, 2).should == ['Sympathy for Mr. Vengeance', 'Chan-wook Park', 2002, 2002]
+  end
+
+  it "returns a new empty Array if no arguments given" do
+    @movie.values_at().should == []
   end
 
   it "fails when passed unsupported types" do
-    car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car.values_at('make') }.should raise_error(TypeError)
+    -> { @movie.values_at('make') }.should.raise(TypeError, "no implicit conversion of String into Integer")
   end
 end
diff --git a/spec/ruby/core/symbol/all_symbols_spec.rb b/spec/ruby/core/symbol/all_symbols_spec.rb
index ef2b4f85e6..689f6211de 100644
--- a/spec/ruby/core/symbol/all_symbols_spec.rb
+++ b/spec/ruby/core/symbol/all_symbols_spec.rb
@@ -1,14 +1,19 @@
 require_relative '../../spec_helper'
 
 describe "Symbol.all_symbols" do
-  it "returns an array containing all the Symbols in the symbol table" do
+  it "returns an array of Symbols" do
     all_symbols = Symbol.all_symbols
-    all_symbols.should be_an_instance_of(Array)
-    all_symbols.all? { |s| s.is_a?(Symbol) ? true : (p s; false) }.should == true
+    all_symbols.should.instance_of?(Array)
+    all_symbols.each { |s| s.should.instance_of?(Symbol) }
   end
 
-  it "returns an Array containing Symbols that have been created" do
+  it "includes symbols that are strongly referenced" do
     symbol = "symbol_specs_#{rand(5_000_000)}".to_sym
-    Symbol.all_symbols.should include(symbol)
+    Symbol.all_symbols.should.include?(symbol)
+  end
+
+  it "includes symbols that are referenced in source code but not yet executed" do
+    Symbol.all_symbols.any? { |s| s.to_s == 'symbol_specs_referenced_in_source_code' }.should == true
+    :symbol_specs_referenced_in_source_code
   end
 end
diff --git a/spec/ruby/core/symbol/capitalize_spec.rb b/spec/ruby/core/symbol/capitalize_spec.rb
index a84bcf280a..a93d951e6a 100644
--- a/spec/ruby/core/symbol/capitalize_spec.rb
+++ b/spec/ruby/core/symbol/capitalize_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "Symbol#capitalize" do
   it "returns a Symbol" do
-    :glark.capitalize.should be_an_instance_of(Symbol)
+    :glark.capitalize.should.instance_of?(Symbol)
   end
 
   it "converts the first character to uppercase if it is ASCII" do
diff --git a/spec/ruby/core/symbol/casecmp_spec.rb b/spec/ruby/core/symbol/casecmp_spec.rb
index b485101d63..dcb77a8350 100644
--- a/spec/ruby/core/symbol/casecmp_spec.rb
+++ b/spec/ruby/core/symbol/casecmp_spec.rb
@@ -56,20 +56,24 @@ describe "Symbol#casecmp with Symbol" do
     lower_a_tilde.casecmp(upper_a_tilde).should == 1
     lower_a_umlaut.casecmp(upper_a_umlaut).should == 1
   end
+
+  it "returns 0 for empty strings in different encodings" do
+    ''.to_sym.casecmp(''.encode("UTF-32LE").to_sym).should == 0
+  end
 end
 
 describe "Symbol#casecmp" do
   it "returns nil if other is a String" do
-    :abc.casecmp("abc").should be_nil
+    :abc.casecmp("abc").should == nil
   end
 
-  it "returns nil if other is a Fixnum" do
-    :abc.casecmp(1).should be_nil
+  it "returns nil if other is an Integer" do
+    :abc.casecmp(1).should == nil
   end
 
   it "returns nil if other is an object" do
     obj = mock("string <=>")
-    :abc.casecmp(obj).should be_nil
+    :abc.casecmp(obj).should == nil
   end
 end
 
@@ -141,4 +145,8 @@ describe 'Symbol#casecmp?' do
     upper_a_tilde.casecmp?(lower_a_tilde).should == nil
     lower_a_tilde.casecmp?(upper_a_tilde).should == nil
   end
+
+  it "returns true for empty symbols in different encodings" do
+    ''.to_sym.should.casecmp?(''.encode("UTF-32LE").to_sym)
+  end
 end
diff --git a/spec/ruby/core/symbol/comparison_spec.rb b/spec/ruby/core/symbol/comparison_spec.rb
index 173a7da625..6d56176e97 100644
--- a/spec/ruby/core/symbol/comparison_spec.rb
+++ b/spec/ruby/core/symbol/comparison_spec.rb
@@ -37,15 +37,15 @@ end
 
 describe "Symbol#<=>" do
   it "returns nil if other is a String" do
-    (:abc <=> "abc").should be_nil
+    (:abc <=> "abc").should == nil
   end
 
-  it "returns nil if other is a Fixnum" do
-    (:abc <=> 1).should be_nil
+  it "returns nil if other is an Integer" do
+    (:abc <=> 1).should == nil
   end
 
   it "returns nil if other is an object" do
     obj = mock("string <=>")
-    (:abc <=> obj).should be_nil
+    (:abc <=> obj).should == nil
   end
 end
diff --git a/spec/ruby/core/symbol/downcase_spec.rb b/spec/ruby/core/symbol/downcase_spec.rb
index 7e94c669cc..76418aa9da 100644
--- a/spec/ruby/core/symbol/downcase_spec.rb
+++ b/spec/ruby/core/symbol/downcase_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "Symbol#downcase" do
   it "returns a Symbol" do
-    :glark.downcase.should be_an_instance_of(Symbol)
+    :glark.downcase.should.instance_of?(Symbol)
   end
 
   it "converts uppercase ASCII characters to their lowercase equivalents" do
diff --git a/spec/ruby/core/symbol/dup_spec.rb b/spec/ruby/core/symbol/dup_spec.rb
index 8b35917c27..eef3078030 100644
--- a/spec/ruby/core/symbol/dup_spec.rb
+++ b/spec/ruby/core/symbol/dup_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "Symbol#dup" do
   it "returns self" do
-    :a_symbol.dup.should equal(:a_symbol)
+    :a_symbol.dup.should.equal?(:a_symbol)
   end
 end
diff --git a/spec/ruby/core/symbol/empty_spec.rb b/spec/ruby/core/symbol/empty_spec.rb
index 19c23cfe5f..1d90a59a5b 100644
--- a/spec/ruby/core/symbol/empty_spec.rb
+++ b/spec/ruby/core/symbol/empty_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Symbol#empty?" do
   it "returns true if self is empty" do
-    :"".empty?.should be_true
+    :"".empty?.should == true
   end
 
   it "returns false if self is non-empty" do
-    :"a".empty?.should be_false
+    :"a".empty?.should == false
   end
 end
diff --git a/spec/ruby/core/symbol/end_with_spec.rb b/spec/ruby/core/symbol/end_with_spec.rb
new file mode 100644
index 0000000000..4b9f5a4996
--- /dev/null
+++ b/spec/ruby/core/symbol/end_with_spec.rb
@@ -0,0 +1,8 @@
+# -*- encoding: utf-8 -*-
+
+require_relative '../../spec_helper'
+require_relative '../../shared/string/end_with'
+
+describe "Symbol#end_with?" do
+  it_behaves_like :end_with, :to_sym
+end
diff --git a/spec/ruby/core/symbol/inspect_spec.rb b/spec/ruby/core/symbol/inspect_spec.rb
index 58402ab261..f2269996af 100644
--- a/spec/ruby/core/symbol/inspect_spec.rb
+++ b/spec/ruby/core/symbol/inspect_spec.rb
@@ -5,6 +5,8 @@ describe "Symbol#inspect" do
     fred:         ":fred",
     :fred?     => ":fred?",
     :fred!     => ":fred!",
+    :BAD!      => ":BAD!",
+    :_BAD!     => ":_BAD!",
     :$ruby     => ":$ruby",
     :@ruby     => ":@ruby",
     :@@ruby    => ":@@ruby",
@@ -64,9 +66,9 @@ describe "Symbol#inspect" do
     :~         => ":~",
     :|         => ":|",
 
-    :"!"       => [":\"!\"",  ":!" ],
-    :"!="      => [":\"!=\"", ":!="],
-    :"!~"      => [":\"!~\"", ":!~"],
+    :"!"       => ":!",
+    :"!="      => ":!=",
+    :"!~"      => ":!~",
     :"\$"      => ":\"$\"", # for justice!
     :"&&"      => ":\"&&\"",
     :"'"       => ":\"\'\"",
@@ -94,12 +96,36 @@ describe "Symbol#inspect" do
     :"foo "    => ":\"foo \"",
     :" foo"    => ":\" foo\"",
     :" "       => ":\" \"",
+
+    :"ê"       => [":ê", ":\"\\u00EA\""],
+    :"测"      => [":测", ":\"\\u6D4B\""],
+    :"🦊"      => [":🦊", ":\"\\u{1F98A}\""],
   }
 
+  expected_by_encoding = Encoding::default_external == Encoding::UTF_8 ? 0 : 1
   symbols.each do |input, expected|
-    expected = expected[1] if expected.is_a?(Array)
+    expected = expected[expected_by_encoding] if expected.is_a?(Array)
     it "returns self as a symbol literal for #{expected}" do
       input.inspect.should == expected
     end
   end
+
+  it "quotes BINARY symbols" do
+    sym = "foo\xA4".b.to_sym
+    sym.inspect.should == ':"foo\xA4"'
+  end
+
+  it "quotes symbols in non-ASCII-compatible encodings" do
+    Encoding.list.reject(&:ascii_compatible?).reject(&:dummy?).each do |encoding|
+      sym = "foo".encode(encoding).to_sym
+      sym.inspect.should == ':"foo"'
+    end
+  end
+
+  it "quotes and escapes symbols in dummy encodings" do
+    Encoding.list.select(&:dummy?).each do |encoding|
+      sym = "abcd".dup.force_encoding(encoding).to_sym
+      sym.inspect.should == ':"\x61\x62\x63\x64"'
+    end
+  end
 end
diff --git a/spec/ruby/core/symbol/intern_spec.rb b/spec/ruby/core/symbol/intern_spec.rb
index ea04b87e8a..9d0914c7fb 100644
--- a/spec/ruby/core/symbol/intern_spec.rb
+++ b/spec/ruby/core/symbol/intern_spec.rb
@@ -6,6 +6,6 @@ describe "Symbol#intern" do
   end
 
   it "returns a Symbol" do
-    :foo.intern.should be_kind_of(Symbol)
+    :foo.intern.should.is_a?(Symbol)
   end
 end
diff --git a/spec/ruby/core/symbol/match_spec.rb b/spec/ruby/core/symbol/match_spec.rb
index d37155537b..7b165218c6 100644
--- a/spec/ruby/core/symbol/match_spec.rb
+++ b/spec/ruby/core/symbol/match_spec.rb
@@ -6,7 +6,7 @@ describe :symbol_match, shared: true do
   end
 
   it "returns nil if there is no match" do
-    :a.send(@method, /b/).should be_nil
+    :a.send(@method, /b/).should == nil
   end
 
   it "sets the last match pseudo-variables" do
@@ -22,18 +22,35 @@ end
 describe "Symbol#match" do
   it "returns the MatchData" do
     result = :abc.match(/b/)
-    result.should be_kind_of(MatchData)
+    result.should.is_a?(MatchData)
     result[0].should == 'b'
   end
 
   it "returns nil if there is no match" do
-    :a.match(/b/).should be_nil
+    :a.match(/b/).should == nil
   end
 
   it "sets the last match pseudo-variables" do
     :a.match(/(.)/)[0].should == 'a'
     $1.should == "a"
   end
+
+  describe "when passed a block" do
+    it "yields the MatchData" do
+      :abc.match(/./) {|m| ScratchPad.record m }
+      ScratchPad.recorded.should.is_a?(MatchData)
+    end
+
+    it "returns the block result" do
+      :abc.match(/./) { :result }.should == :result
+    end
+
+    it "does not yield if there is no match" do
+      ScratchPad.record []
+      :b.match(/a/) {|m| ScratchPad << m }
+      ScratchPad.recorded.should == []
+    end
+  end
 end
 
 describe "Symbol#match?" do
@@ -44,17 +61,17 @@ describe "Symbol#match?" do
 
   context "when matches the given regex" do
     it "returns true but does not set Regexp.last_match" do
-      :string.match?(/string/i).should be_true
-      Regexp.last_match.should be_nil
+      :string.match?(/string/i).should == true
+      Regexp.last_match.should == nil
     end
   end
 
   it "returns false when does not match the given regex" do
-    :string.match?(/STRING/).should be_false
+    :string.match?(/STRING/).should == false
   end
 
   it "takes matching position as the 2nd argument" do
-    :string.match?(/str/i, 0).should be_true
-    :string.match?(/str/i, 1).should be_false
+    :string.match?(/str/i, 0).should == true
+    :string.match?(/str/i, 1).should == false
   end
 end
diff --git a/spec/ruby/core/symbol/name_spec.rb b/spec/ruby/core/symbol/name_spec.rb
new file mode 100644
index 0000000000..f9b631266c
--- /dev/null
+++ b/spec/ruby/core/symbol/name_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+
+describe "Symbol#name" do
+  it "returns string" do
+    :ruby.name.should == "ruby"
+    :ルビー.name.should == "ルビー"
+  end
+
+  it "returns same string instance" do
+    :"ruby_3".name.should.equal?(:ruby_3.name)
+    :"ruby_#{1+2}".name.should.equal?(:ruby_3.name)
+  end
+
+  it "returns frozen string" do
+    :symbol.name.should.frozen?
+  end
+end
diff --git a/spec/ruby/core/symbol/shared/id2name.rb b/spec/ruby/core/symbol/shared/id2name.rb
index a0e190a680..00a9c7d7dc 100644
--- a/spec/ruby/core/symbol/shared/id2name.rb
+++ b/spec/ruby/core/symbol/shared/id2name.rb
@@ -7,20 +7,24 @@ describe :symbol_id2name, shared: true do
     :@@ruby.send(@method).should == "@@ruby"
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen String" do
-      :my_symbol.to_s.frozen?.should == true
-      :"dynamic symbol #{6 * 7}".to_s.frozen?.should == true
-    end
+  it "returns a String in the same encoding as self" do
+    string = "ruby".encode("US-ASCII")
+    symbol = string.to_sym
+
+    symbol.send(@method).encoding.should == Encoding::US_ASCII
+  end
 
-    it "always returns the same String for a given Symbol" do
-      s1 = :my_symbol.to_s
-      s2 = :my_symbol.to_s
-      s1.should equal(s2)
+  ruby_version_is "3.4" do
+    it "warns about mutating returned string" do
+      -> { :bad!.send(@method).upcase! }.should complain(/warning: string returned by :bad!.to_s will be frozen in the future/)
+    end
 
-      s1 = :"dynamic symbol #{6 * 7}".to_s
-      s2 = :"dynamic symbol #{2 * 3 * 7}".to_s
-      s1.should equal(s2)
+    it "does not warn about mutation when Warning[:deprecated] is false" do
+      deprecated = Warning[:deprecated]
+      Warning[:deprecated] = false
+      -> { :bad!.send(@method).upcase! }.should_not complain
+    ensure
+      Warning[:deprecated] = deprecated
     end
   end
 end
diff --git a/spec/ruby/core/symbol/shared/slice.rb b/spec/ruby/core/symbol/shared/slice.rb
index 478e0d80ae..4e3a35240c 100644
--- a/spec/ruby/core/symbol/shared/slice.rb
+++ b/spec/ruby/core/symbol/shared/slice.rb
@@ -7,11 +7,11 @@ describe :symbol_slice, shared: true do
     end
 
     it "returns nil if the index starts from the end and is greater than the length" do
-        :symbol.send(@method, -10).should be_nil
+      :symbol.send(@method, -10).should == nil
     end
 
     it "returns nil if the index is greater than the length" do
-      :symbol.send(@method, 42).should be_nil
+      :symbol.send(@method, 42).should == nil
     end
   end
 
@@ -31,14 +31,14 @@ describe :symbol_slice, shared: true do
       end
 
       it "returns nil if the index is greater than the length" do
-        :symbol.send(@method, 10,1).should be_nil
+        :symbol.send(@method, 10,1).should == nil
       end
     end
 
     describe "and a positive index and negative length" do
       it "returns nil" do
-        :symbol.send(@method, 0,-1).should be_nil
-        :symbol.send(@method, 1,-1).should be_nil
+        :symbol.send(@method, 0,-1).should == nil
+        :symbol.send(@method, 1,-1).should == nil
       end
     end
 
@@ -56,13 +56,13 @@ describe :symbol_slice, shared: true do
       end
 
       it "returns nil if the index is past the start" do
-        :symbol.send(@method, -10,1).should be_nil
+        :symbol.send(@method, -10,1).should == nil
       end
     end
 
     describe "and a negative index and negative length" do
       it "returns nil" do
-        :symbol.send(@method, -1,-1).should be_nil
+        :symbol.send(@method, -1,-1).should == nil
       end
     end
 
@@ -74,21 +74,21 @@ describe :symbol_slice, shared: true do
 
     describe "and a nil length" do
       it "raises a TypeError" do
-        -> { :symbol.send(@method, 1,nil) }.should raise_error(TypeError)
+        -> { :symbol.send(@method, 1,nil) }.should.raise(TypeError)
       end
     end
 
     describe "and a length that cannot be converted into an Integer" do
       it "raises a TypeError when given an Array" do
-        -> { :symbol.send(@method, 1,Array.new) }.should raise_error(TypeError)
+        -> { :symbol.send(@method, 1,Array.new) }.should.raise(TypeError)
       end
 
       it "raises a TypeError when given an Hash" do
-        -> { :symbol.send(@method, 1,Hash.new) }.should raise_error(TypeError)
+        -> { :symbol.send(@method, 1,Hash.new) }.should.raise(TypeError)
       end
 
       it "raises a TypeError when given an Object" do
-        -> { :symbol.send(@method, 1,Object.new) }.should raise_error(TypeError)
+        -> { :symbol.send(@method, 1,Object.new) }.should.raise(TypeError)
       end
     end
   end
@@ -101,21 +101,21 @@ describe :symbol_slice, shared: true do
 
   describe "with a nil index" do
     it "raises a TypeError" do
-      -> { :symbol.send(@method, nil) }.should raise_error(TypeError)
+      -> { :symbol.send(@method, nil) }.should.raise(TypeError)
     end
   end
 
   describe "with an index that cannot be converted into an Integer" do
     it "raises a TypeError when given an Array" do
-      -> { :symbol.send(@method, Array.new) }.should raise_error(TypeError)
+      -> { :symbol.send(@method, Array.new) }.should.raise(TypeError)
     end
 
     it "raises a TypeError when given an Hash" do
-      -> { :symbol.send(@method, Hash.new) }.should raise_error(TypeError)
+      -> { :symbol.send(@method, Hash.new) }.should.raise(TypeError)
     end
 
     it "raises a TypeError when given an Object" do
-      -> { :symbol.send(@method, Object.new) }.should raise_error(TypeError)
+      -> { :symbol.send(@method, Object.new) }.should.raise(TypeError)
     end
   end
 
@@ -136,7 +136,7 @@ describe :symbol_slice, shared: true do
 
     describe "that is out of bounds" do
       it "returns nil if the first range value begins past the end" do
-        :symbol.send(@method, 10..12).should be_nil
+        :symbol.send(@method, 10..12).should == nil
       end
 
       it "returns a blank string if the first range value is within bounds and the last range value is not" do
@@ -145,11 +145,11 @@ describe :symbol_slice, shared: true do
       end
 
       it "returns nil if the first range value starts from the end and is within bounds and the last value starts from the end and is greater than the length" do
-        :symbol.send(@method, -10..-12).should be_nil
+        :symbol.send(@method, -10..-12).should == nil
       end
 
       it "returns nil if the first range value starts from the end and is out of bounds and the last value starts from the end and is less than the length" do
-        :symbol.send(@method, -10..-2).should be_nil
+        :symbol.send(@method, -10..-2).should == nil
       end
     end
 
@@ -178,7 +178,7 @@ describe :symbol_slice, shared: true do
       end
 
       it "returns nil if the expression does not match" do
-        :symbol.send(@method, /0-9/).should be_nil
+        :symbol.send(@method, /0-9/).should == nil
       end
 
       it "sets $~ to the MatchData if there is a match" do
@@ -188,15 +188,7 @@ describe :symbol_slice, shared: true do
 
       it "does not set $~ if there if there is not a match" do
         :symbol.send(@method, /[0-9]+/)
-        $~.should be_nil
-      end
-
-      it "returns a tainted string if the regexp is tainted" do
-        :symbol.send(@method, /./.taint).tainted?.should be_true
-      end
-
-      it "returns an untrusted string if the regexp is untrusted" do
-        :symbol.send(@method, /./.untrust).untrusted?.should be_true
+        $~.should == nil
       end
     end
 
@@ -211,38 +203,30 @@ describe :symbol_slice, shared: true do
       end
 
       it "returns nil if there is no capture for the index" do
-        :symbol.send(@method, /(sy)(mb)(ol)/, 4).should be_nil
-        :symbol.send(@method, /(sy)(mb)(ol)/, -4).should be_nil
+        :symbol.send(@method, /(sy)(mb)(ol)/, 4).should == nil
+        :symbol.send(@method, /(sy)(mb)(ol)/, -4).should == nil
       end
 
       it "converts the index to an Integer" do
         :symbol.send(@method, /(sy)(mb)(ol)/, 1.5).should == "sy"
       end
 
-      it "returns a tainted string if the regexp is tainted" do
-        :symbol.send(@method, /(.)/.taint, 1).tainted?.should be_true
-      end
-
-      it "returns an untrusted string if the regexp is untrusted" do
-        :symbol.send(@method, /(.)/.untrust, 1).untrusted?.should be_true
-      end
-
       describe "and an index that cannot be converted to an Integer" do
         it "raises a TypeError when given an Hash" do
-          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Hash.new) }.should raise_error(TypeError)
+          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Hash.new) }.should.raise(TypeError)
         end
 
         it "raises a TypeError when given an Array" do
-          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Array.new) }.should raise_error(TypeError)
+          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Array.new) }.should.raise(TypeError)
         end
 
         it "raises a TypeError when given an Object" do
-          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Object.new) }.should raise_error(TypeError)
+          -> { :symbol.send(@method, /(sy)(mb)(ol)/, Object.new) }.should.raise(TypeError)
         end
       end
 
       it "raises a TypeError if the index is nil" do
-        -> { :symbol.send(@method, /(sy)(mb)(ol)/, nil) }.should raise_error(TypeError)
+        -> { :symbol.send(@method, /(sy)(mb)(ol)/, nil) }.should.raise(TypeError)
       end
 
       it "sets $~ to the MatchData if there is a match" do
@@ -255,7 +239,7 @@ describe :symbol_slice, shared: true do
 
       it "does not set $~ to the MatchData if there is not a match" do
         :symbol.send(@method, /0-9/, 0)
-        $~.should be_nil
+        $~.should == nil
       end
     end
   end
@@ -264,7 +248,7 @@ describe :symbol_slice, shared: true do
     it "does not set $~" do
       $~ = nil
       :symbol.send(@method, "sym")
-      $~.should be_nil
+      $~.should == nil
     end
 
     it "returns a string if there is match" do
@@ -272,7 +256,7 @@ describe :symbol_slice, shared: true do
     end
 
     it "returns nil if there is not a match" do
-      :symbol.send(@method, "foo").should be_nil
+      :symbol.send(@method, "foo").should == nil
     end
   end
 end
diff --git a/spec/ruby/core/symbol/start_with_spec.rb b/spec/ruby/core/symbol/start_with_spec.rb
new file mode 100644
index 0000000000..cd43279003
--- /dev/null
+++ b/spec/ruby/core/symbol/start_with_spec.rb
@@ -0,0 +1,8 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative '../../shared/string/start_with'
+
+describe "Symbol#start_with?" do
+  it_behaves_like :start_with, :to_sym
+end
diff --git a/spec/ruby/core/symbol/swapcase_spec.rb b/spec/ruby/core/symbol/swapcase_spec.rb
index 24709cac30..95fc29e32b 100644
--- a/spec/ruby/core/symbol/swapcase_spec.rb
+++ b/spec/ruby/core/symbol/swapcase_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "Symbol#swapcase" do
   it "returns a Symbol" do
-    :glark.swapcase.should be_an_instance_of(Symbol)
+    :glark.swapcase.should.instance_of?(Symbol)
   end
 
   it "converts lowercase ASCII characters to their uppercase equivalents" do
diff --git a/spec/ruby/core/symbol/symbol_spec.rb b/spec/ruby/core/symbol/symbol_spec.rb
index cefe70bc99..3534686a08 100644
--- a/spec/ruby/core/symbol/symbol_spec.rb
+++ b/spec/ruby/core/symbol/symbol_spec.rb
@@ -8,12 +8,12 @@ describe "Symbol" do
   it ".allocate raises a TypeError" do
     -> do
       Symbol.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       Symbol.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/symbol/to_proc_spec.rb b/spec/ruby/core/symbol/to_proc_spec.rb
index 60e33d7cb8..93ed1e9e9b 100644
--- a/spec/ruby/core/symbol/to_proc_spec.rb
+++ b/spec/ruby/core/symbol/to_proc_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "Symbol#to_proc" do
   it "returns a new Proc" do
     proc = :to_s.to_proc
-    proc.should be_kind_of(Proc)
+    proc.should.is_a?(Proc)
   end
 
   it "sends self to arguments passed when calling #call on the Proc" do
@@ -12,18 +12,50 @@ describe "Symbol#to_proc" do
     :to_s.to_proc.call(obj).should == "Received #to_s"
   end
 
-  it "produces a proc with arity -1" do
+  it "returns a Proc with #lambda? true" do
     pr = :to_s.to_proc
-    pr.arity.should == -1
+    pr.should.lambda?
   end
 
-  it "raises an ArgumentError when calling #call on the Proc without receiver" do
-    -> { :object_id.to_proc.call }.should raise_error(ArgumentError, "no receiver given")
+  it "produces a Proc with arity -2" do
+    pr = :to_s.to_proc
+    pr.arity.should == -2
   end
 
-  it "produces a proc that always returns [[:rest]] for #parameters" do
+  it "produces a Proc that always returns [[:req], [:rest]] for #parameters" do
     pr = :to_s.to_proc
-    pr.parameters.should == [[:rest]]
+    pr.parameters.should == [[:req], [:rest]]
+  end
+
+  it "only calls public methods" do
+    body = proc do
+      public def pub; @a << :pub end
+      protected def pro; @a << :pro end
+      private def pri; @a << :pri end
+      attr_reader :a
+    end
+
+    @a = []
+    singleton_class.class_eval(&body)
+    tap(&:pub)
+    proc{tap(&:pro)}.should.raise(NoMethodError, /protected method [`']pro' called/)
+    proc{tap(&:pri)}.should.raise(NoMethodError, /private method [`']pri' called/)
+    @a.should == [:pub]
+
+    @a = []
+    c = Class.new(&body)
+    o = c.new
+    o.instance_variable_set(:@a, [])
+    o.tap(&:pub)
+    proc{tap(&:pro)}.should.raise(NoMethodError, /protected method [`']pro' called/)
+    proc{o.tap(&:pri)}.should.raise(NoMethodError, /private method [`']pri' called/)
+    o.a.should == [:pub]
+  end
+
+  it "raises an ArgumentError when calling #call on the Proc without receiver" do
+    -> {
+      :object_id.to_proc.call
+    }.should.raise(ArgumentError, /no receiver given|wrong number of arguments \(given 0, expected 1\+\)/)
   end
 
   it "passes along the block passed to Proc#call" do
@@ -38,4 +70,9 @@ describe "Symbol#to_proc" do
     end
     klass.new.to_proc.should == :value
   end
+
+  it "produces a proc with source location nil" do
+    pr = :to_s.to_proc
+    pr.source_location.should == nil
+  end
 end
diff --git a/spec/ruby/core/symbol/upcase_spec.rb b/spec/ruby/core/symbol/upcase_spec.rb
index f704bdcbf3..3895d95efb 100644
--- a/spec/ruby/core/symbol/upcase_spec.rb
+++ b/spec/ruby/core/symbol/upcase_spec.rb
@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 
 describe "Symbol#upcase" do
   it "returns a Symbol" do
-    :glark.upcase.should be_an_instance_of(Symbol)
+    :glark.upcase.should.instance_of?(Symbol)
   end
 
   it "converts lowercase ASCII characters to their uppercase equivalents" do
diff --git a/spec/ruby/core/systemexit/success_spec.rb b/spec/ruby/core/systemexit/success_spec.rb
index 6d36509c80..ba2fd22ded 100644
--- a/spec/ruby/core/systemexit/success_spec.rb
+++ b/spec/ruby/core/systemexit/success_spec.rb
@@ -3,11 +3,11 @@ require_relative '../../spec_helper'
 describe "SystemExit#success?" do
   it "returns true when the status is 0" do
     s = SystemExit.new 0
-    s.success?.should == true
+    s.should.success?
   end
 
   it "returns false when the status is not 0" do
     s = SystemExit.new 1
-    s.success?.should == false
+    s.should_not.success?
   end
 end
diff --git a/spec/ruby/core/thread/abort_on_exception_spec.rb b/spec/ruby/core/thread/abort_on_exception_spec.rb
index 34b648ca0f..aeca50e5c1 100644
--- a/spec/ruby/core/thread/abort_on_exception_spec.rb
+++ b/spec/ruby/core/thread/abort_on_exception_spec.rb
@@ -13,12 +13,12 @@ describe "Thread#abort_on_exception" do
   end
 
   it "is false by default" do
-    @thread.abort_on_exception.should be_false
+    @thread.abort_on_exception.should == false
   end
 
   it "returns true when #abort_on_exception= is passed true" do
     @thread.abort_on_exception = true
-    @thread.abort_on_exception.should be_true
+    @thread.abort_on_exception.should == true
   end
 end
 
@@ -39,7 +39,7 @@ describe :thread_abort_on_exception, shared: true do
         ThreadSpecs.state = :run
         # Wait for the main thread to be interrupted
         sleep
-      end.should raise_error(RuntimeError, "Thread#abort_on_exception= specs")
+      end.should.raise(RuntimeError, "Thread#abort_on_exception= specs")
 
       ScratchPad << :after
     rescue Exception => e
@@ -72,7 +72,7 @@ describe "Thread.abort_on_exception" do
   end
 
   after do
-     Thread.abort_on_exception = @abort_on_exception
+    Thread.abort_on_exception = @abort_on_exception
   end
 
   it "is false by default" do
@@ -81,7 +81,7 @@ describe "Thread.abort_on_exception" do
 
   it "returns true when .abort_on_exception= is passed true" do
     Thread.abort_on_exception = true
-    Thread.abort_on_exception.should be_true
+    Thread.abort_on_exception.should == true
   end
 end
 
diff --git a/spec/ruby/core/thread/alive_spec.rb b/spec/ruby/core/thread/alive_spec.rb
index d4ba149d87..c2f5f5371d 100644
--- a/spec/ruby/core/thread/alive_spec.rb
+++ b/spec/ruby/core/thread/alive_spec.rb
@@ -3,39 +3,39 @@ require_relative 'fixtures/classes'
 
 describe "Thread#alive?" do
   it "can check it's own status" do
-    ThreadSpecs.status_of_current_thread.alive?.should == true
+    ThreadSpecs.status_of_current_thread.should.alive?
   end
 
   it "describes a running thread" do
-    ThreadSpecs.status_of_running_thread.alive?.should == true
+    ThreadSpecs.status_of_running_thread.should.alive?
   end
 
   it "describes a sleeping thread" do
-    ThreadSpecs.status_of_sleeping_thread.alive?.should == true
+    ThreadSpecs.status_of_sleeping_thread.should.alive?
   end
 
   it "describes a blocked thread" do
-    ThreadSpecs.status_of_blocked_thread.alive?.should == true
+    ThreadSpecs.status_of_blocked_thread.should.alive?
   end
 
   it "describes a completed thread" do
-    ThreadSpecs.status_of_completed_thread.alive?.should == false
+    ThreadSpecs.status_of_completed_thread.should_not.alive?
   end
 
   it "describes a killed thread" do
-    ThreadSpecs.status_of_killed_thread.alive?.should == false
+    ThreadSpecs.status_of_killed_thread.should_not.alive?
   end
 
   it "describes a thread with an uncaught exception" do
-    ThreadSpecs.status_of_thread_with_uncaught_exception.alive?.should == false
+    ThreadSpecs.status_of_thread_with_uncaught_exception.should_not.alive?
   end
 
   it "describes a dying running thread" do
-    ThreadSpecs.status_of_dying_running_thread.alive?.should == true
+    ThreadSpecs.status_of_dying_running_thread.should.alive?
   end
 
   it "describes a dying sleeping thread" do
-    ThreadSpecs.status_of_dying_sleeping_thread.alive?.should == true
+    ThreadSpecs.status_of_dying_sleeping_thread.should.alive?
   end
 
   it "returns true for a killed but still running thread" do
@@ -51,7 +51,7 @@ describe "Thread#alive?" do
     ThreadSpecs.spin_until_sleeping(t)
 
     t.kill
-    t.alive?.should == true
+    t.should.alive?
     exit = true
     t.join
   end
diff --git a/spec/ruby/core/thread/allocate_spec.rb b/spec/ruby/core/thread/allocate_spec.rb
index cfd556812f..0b4e4f1b1f 100644
--- a/spec/ruby/core/thread/allocate_spec.rb
+++ b/spec/ruby/core/thread/allocate_spec.rb
@@ -4,6 +4,6 @@ describe "Thread.allocate" do
   it "raises a TypeError" do
     -> {
       Thread.allocate
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/thread/backtrace/limit_spec.rb b/spec/ruby/core/thread/backtrace/limit_spec.rb
new file mode 100644
index 0000000000..b55ca67ea0
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace/limit_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../../spec_helper'
+
+describe "Thread::Backtrace.limit" do
+  it "returns maximum backtrace length set by --backtrace-limit command-line option" do
+    out = ruby_exe("print Thread::Backtrace.limit", options: "--backtrace-limit=2")
+    out.should == "2"
+  end
+
+  it "returns -1 when --backtrace-limit command-line option is not set" do
+    out = ruby_exe("print Thread::Backtrace.limit")
+    out.should == "-1"
+  end
+end
diff --git a/spec/ruby/core/thread/backtrace/location/absolute_path_spec.rb b/spec/ruby/core/thread/backtrace/location/absolute_path_spec.rb
index d38659c257..6d9482f2ae 100644
--- a/spec/ruby/core/thread/backtrace/location/absolute_path_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/absolute_path_spec.rb
@@ -10,11 +10,28 @@ describe 'Thread::Backtrace::Location#absolute_path' do
     @frame.absolute_path.should == File.realpath(__FILE__)
   end
 
+  it 'returns an absolute path when using a relative main script path' do
+    script = fixture(__FILE__, 'absolute_path_main.rb')
+    Dir.chdir(File.dirname(script)) do
+      ruby_exe('absolute_path_main.rb').should == "absolute_path_main.rb\n#{script}\n"
+    end
+  end
+
+  it 'returns the correct absolute path when using a relative main script path and changing CWD' do
+    script = fixture(__FILE__, 'subdir/absolute_path_main_chdir.rb')
+    sibling = fixture(__FILE__, 'subdir/sibling.rb')
+    subdir = File.dirname script
+    Dir.chdir(fixture(__FILE__)) do
+      ruby_exe('subdir/absolute_path_main_chdir.rb').should == "subdir/absolute_path_main_chdir.rb\n#{subdir}\n#{subdir}\n#{script}\n#{sibling}\n"
+    end
+  end
+
   context "when used in eval with a given filename" do
-    it "returns filename" do
+    it "returns nil with absolute_path" do
       code = "caller_locations(0)[0].absolute_path"
-      eval(code, nil, "foo.rb").should == "foo.rb"
-      eval(code, nil, "foo/bar.rb").should == "foo/bar.rb"
+
+      eval(code, nil, "foo.rb").should == nil
+      eval(code, nil, "foo/bar.rb").should == nil
     end
   end
 
@@ -25,37 +42,52 @@ describe 'Thread::Backtrace::Location#absolute_path' do
       locations = ScratchPad.recorded
       locations[0].absolute_path.should == path
       # Make sure it's from the class body, not from the file top-level
-      locations[0].label.should include 'MethodAddedAbsolutePath'
+      locations[0].label.should.include? 'MethodAddedAbsolutePath'
     end
   end
 
-  platform_is_not :windows do
-    before :each do
-      @file = fixture(__FILE__, "absolute_path.rb")
-      @symlink = tmp("symlink.rb")
-      File.symlink(@file, @symlink)
-      ScratchPad.record []
+  context "when used in a core method" do
+    it "returns nil" do
+      location = nil
+      tap { location = caller_locations(1, 1)[0] }
+      location.label.should =~ /\A(?:Kernel#)?tap\z/
+      if location.path.start_with?("<internal:")
+        location.absolute_path.should == nil
+      else
+        location.absolute_path.should == File.realpath(__FILE__)
+      end
     end
+  end
 
-    after :each do
-      rm_r @symlink
-    end
+  context "canonicalization" do
+    platform_is_not :windows do
+      before :each do
+        @file = fixture(__FILE__, "absolute_path.rb")
+        @symlink = tmp("symlink.rb")
+        File.symlink(@file, @symlink)
+        ScratchPad.record []
+      end
 
-    it "returns a canonical path without symlinks, even when __FILE__ does not" do
-      realpath = File.realpath(@symlink)
-      realpath.should_not == @symlink
+      after :each do
+        rm_r @symlink
+      end
 
-      load @symlink
-      ScratchPad.recorded.should == [@symlink, realpath]
-    end
+      it "returns a canonical path without symlinks, even when __FILE__ does not" do
+        realpath = File.realpath(@symlink)
+        realpath.should_not == @symlink
+
+        load @symlink
+        ScratchPad.recorded.should == [@symlink, realpath]
+      end
 
-    it "returns a canonical path without symlinks, even when __FILE__ is removed" do
-      realpath = File.realpath(@symlink)
-      realpath.should_not == @symlink
+      it "returns a canonical path without symlinks, even when __FILE__ is removed" do
+        realpath = File.realpath(@symlink)
+        realpath.should_not == @symlink
 
-      ScratchPad << -> { rm_r(@symlink) }
-      load @symlink
-      ScratchPad.recorded.should == [@symlink, realpath]
+        ScratchPad << -> { rm_r(@symlink) }
+        load @symlink
+        ScratchPad.recorded.should == [@symlink, realpath]
+      end
     end
   end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/base_label_spec.rb b/spec/ruby/core/thread/backtrace/location/base_label_spec.rb
index 139a68e2c8..739f62f42f 100644
--- a/spec/ruby/core/thread/backtrace/location/base_label_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/base_label_spec.rb
@@ -19,4 +19,31 @@ describe 'Thread::Backtrace::Location#base_label' do
       @frame.base_label.should == 'block_location'
     end
   end
+
+  it "is <module:A> for a module body" do
+    module ThreadBacktraceLocationSpecs
+      module ModuleLabel
+        ScratchPad.record caller_locations(0, 1)[0].base_label
+      end
+    end
+    ScratchPad.recorded.should == '<module:ModuleLabel>'
+  end
+
+  it "is <class:A> for a class body" do
+    module ThreadBacktraceLocationSpecs
+      class ClassLabel
+        ScratchPad.record caller_locations(0, 1)[0].base_label
+      end
+    end
+    ScratchPad.recorded.should == '<class:ClassLabel>'
+  end
+
+  it "is 'singleton class' for a singleton class body" do
+    module ThreadBacktraceLocationSpecs
+      class << Object.new
+        ScratchPad.record caller_locations(0, 1)[0].base_label
+      end
+    end
+    ScratchPad.recorded.should =~ /\A(singleton class|<singleton class>)\z/
+  end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/fixtures/absolute_path_main.rb b/spec/ruby/core/thread/backtrace/location/fixtures/absolute_path_main.rb
new file mode 100644
index 0000000000..d2b23393d4
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace/location/fixtures/absolute_path_main.rb
@@ -0,0 +1,2 @@
+puts __FILE__
+puts caller_locations(0)[0].absolute_path
diff --git a/spec/ruby/core/thread/backtrace/location/fixtures/classes.rb b/spec/ruby/core/thread/backtrace/location/fixtures/classes.rb
index e903c3e450..103c36b3a0 100644
--- a/spec/ruby/core/thread/backtrace/location/fixtures/classes.rb
+++ b/spec/ruby/core/thread/backtrace/location/fixtures/classes.rb
@@ -1,10 +1,26 @@
+# These are top-level def on purpose to test those cases
+
+def label_top_method = ThreadBacktraceLocationSpecs::LABEL.call
+
+def self.label_sdef_method_of_main = ThreadBacktraceLocationSpecs::LABEL.call
+
+class << self
+  def label_sclass_method_of_main = ThreadBacktraceLocationSpecs::LABEL.call
+end
+
 module ThreadBacktraceLocationSpecs
   MODULE_LOCATION = caller_locations(0) rescue nil
+  INSTANCE = Object.new.extend(self)
+  LABEL = -> { caller_locations(1, 1)[0].label }
 
   def self.locations
     caller_locations
   end
 
+  def instance_method_location
+    caller_locations(0)
+  end
+
   def self.method_location
     caller_locations(0)
   end
@@ -15,6 +31,12 @@ module ThreadBacktraceLocationSpecs
     end
   end
 
+  def instance_block_location
+    1.times do
+      return caller_locations(0)
+    end
+  end
+
   def self.locations_inside_nested_blocks
     first_level_location = nil
     second_level_location = nil
@@ -32,4 +54,86 @@ module ThreadBacktraceLocationSpecs
 
     [first_level_location, second_level_location, third_level_location]
   end
+
+  def instance_locations_inside_nested_block
+    loc = nil
+    1.times do
+      1.times do
+        loc = caller_locations(0)
+      end
+    end
+    loc
+  end
+
+  def original_method = LABEL.call
+  alias_method :aliased_method, :original_method
+
+  module M
+    class C
+      def regular_instance_method = LABEL.call
+
+      def self.sdef_class_method = LABEL.call
+
+      class << self
+        def sclass_method = LABEL.call
+
+        def block_in_sclass_method
+          -> {
+            -> { LABEL.call }.call
+          }.call
+        end
+      end
+      block_in_sclass_method
+    end
+  end
+
+  class M::D
+    def scoped_method = LABEL.call
+
+    def self.sdef_scoped_method = LABEL.call
+
+    class << self
+      def sclass_scoped_method = LABEL.call
+    end
+
+    module ::ThreadBacktraceLocationSpecs
+      def top = LABEL.call
+    end
+
+    class ::ThreadBacktraceLocationSpecs::Nested
+      def top_nested = LABEL.call
+
+      class C
+        def top_nested_c = LABEL.call
+      end
+    end
+  end
+
+  SOME_OBJECT = Object.new
+  SOME_OBJECT.instance_exec do
+    def unknown_def_singleton_method = LABEL.call
+
+    def self.unknown_sdef_singleton_method = LABEL.call
+  end
+
+  M.module_eval do
+    def module_eval_method = LABEL.call
+
+    def self.sdef_module_eval_method = LABEL.call
+  end
+
+  def ThreadBacktraceLocationSpecs.string_class_method = LABEL.call
+
+  module M
+    def ThreadBacktraceLocationSpecs.nested_class_method = LABEL.call
+  end
+
+  module M
+    module_function def mod_function = LABEL.call
+  end
+
+  expr = self
+  def expr.sdef_expression = LABEL.call
+
+  def expr.block_in_sdef_expression = -> { LABEL.call }.call
 end
diff --git a/spec/ruby/core/thread/backtrace/location/fixtures/path.rb b/spec/ruby/core/thread/backtrace/location/fixtures/path.rb
new file mode 100644
index 0000000000..fba34cb0bc
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace/location/fixtures/path.rb
@@ -0,0 +1,2 @@
+ScratchPad << __FILE__
+ScratchPad << caller_locations(0)[0].path
diff --git a/spec/ruby/core/thread/backtrace/location/fixtures/subdir/absolute_path_main_chdir.rb b/spec/ruby/core/thread/backtrace/location/fixtures/subdir/absolute_path_main_chdir.rb
new file mode 100644
index 0000000000..33c8fb36ef
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace/location/fixtures/subdir/absolute_path_main_chdir.rb
@@ -0,0 +1,11 @@
+puts __FILE__
+puts __dir__
+Dir.chdir __dir__
+
+# Check __dir__ is still correct after chdir
+puts __dir__
+
+puts caller_locations(0)[0].absolute_path
+
+# require_relative also needs to know the absolute path of the current file so we test it here too
+require_relative 'sibling'
diff --git a/spec/ruby/core/thread/backtrace/location/fixtures/subdir/sibling.rb b/spec/ruby/core/thread/backtrace/location/fixtures/subdir/sibling.rb
new file mode 100644
index 0000000000..2a854ddccd
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace/location/fixtures/subdir/sibling.rb
@@ -0,0 +1 @@
+puts __FILE__
diff --git a/spec/ruby/core/thread/backtrace/location/inspect_spec.rb b/spec/ruby/core/thread/backtrace/location/inspect_spec.rb
index 20e477a5a6..4df88a2f33 100644
--- a/spec/ruby/core/thread/backtrace/location/inspect_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/inspect_spec.rb
@@ -8,6 +8,6 @@ describe 'Thread::Backtrace::Location#inspect' do
   end
 
   it 'converts the call frame to a String' do
-    @frame.inspect.should include("#{__FILE__}:#{@line}:in ")
+    @frame.inspect.should.include?("#{__FILE__}:#{@line}:in ")
   end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/label_spec.rb b/spec/ruby/core/thread/backtrace/location/label_spec.rb
index 7312d017e5..5f6a7b73df 100644
--- a/spec/ruby/core/thread/backtrace/location/label_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/label_spec.rb
@@ -3,28 +3,28 @@ require_relative 'fixtures/classes'
 
 describe 'Thread::Backtrace::Location#label' do
   it 'returns the base label of the call frame' do
-    ThreadBacktraceLocationSpecs.locations[0].label.should include('<top (required)>')
+    ThreadBacktraceLocationSpecs.locations[0].label.should.include?('<top (required)>')
   end
 
   it 'returns the method name for a method location' do
-    ThreadBacktraceLocationSpecs.method_location[0].label.should == "method_location"
+    ThreadBacktraceLocationSpecs.method_location[0].label.should =~ /\A(?:ThreadBacktraceLocationSpecs\.)?method_location\z/
   end
 
   it 'returns the block name for a block location' do
-    ThreadBacktraceLocationSpecs.block_location[0].label.should == "block in block_location"
+    ThreadBacktraceLocationSpecs.block_location[0].label.should =~ /\Ablock in (?:ThreadBacktraceLocationSpecs\.)?block_location\z/
   end
 
   it 'returns the module name for a module location' do
-    ThreadBacktraceLocationSpecs::MODULE_LOCATION[0].label.should include "ThreadBacktraceLocationSpecs"
+    ThreadBacktraceLocationSpecs::MODULE_LOCATION[0].label.should == "<module:ThreadBacktraceLocationSpecs>"
   end
 
   it 'includes the nesting level of a block as part of the location label' do
     first_level_location, second_level_location, third_level_location =
       ThreadBacktraceLocationSpecs.locations_inside_nested_blocks
 
-    first_level_location.label.should == 'block in locations_inside_nested_blocks'
-    second_level_location.label.should == 'block (2 levels) in locations_inside_nested_blocks'
-    third_level_location.label.should == 'block (3 levels) in locations_inside_nested_blocks'
+    first_level_location.label.should =~ /\Ablock in (?:ThreadBacktraceLocationSpecs\.)?locations_inside_nested_blocks\z/
+    second_level_location.label.should =~ /\Ablock \(2 levels\) in (?:ThreadBacktraceLocationSpecs\.)?locations_inside_nested_blocks\z/
+    third_level_location.label.should =~ /\Ablock \(3 levels\) in (?:ThreadBacktraceLocationSpecs\.)?locations_inside_nested_blocks\z/
   end
 
   it 'sets the location label for a top-level block differently depending on it being in the main file or a required file' do
@@ -34,4 +34,194 @@ describe 'Thread::Backtrace::Location#label' do
     main_label.should == "block in <main>\n"
     required_label.should == "block in <top (required)>\n"
   end
+
+  it "return the same name as the caller for eval" do
+    this = caller_locations(0)[0].label
+    eval("caller_locations(0)[0]").label.should == this
+
+    b = binding
+    b.eval("caller_locations(0)[0]").label.should == this
+
+    b.local_variable_set(:binding_var1, 1)
+    b.eval("caller_locations(0)[0]").label.should == this
+
+    b.local_variable_set(:binding_var2, 2)
+    b.eval("caller_locations(0)[0]").label.should == this
+
+    b.local_variable_set(:binding_var2, 2)
+    eval("caller_locations(0)[0]", b).label.should == this
+  end
+
+  ruby_version_is "3.4" do
+    describe "is Module#method for" do
+      it "a core method defined natively" do
+        BasicObject.instance_method(:instance_exec).should_not.source_location
+        loc = nil
+        loc = instance_exec { caller_locations(1, 1)[0] }
+        loc.label.should == "BasicObject#instance_exec"
+      end
+
+      it "a core method defined in Ruby" do
+        Kernel.instance_method(:tap).should.source_location
+        loc = nil
+        tap { loc = caller_locations(1, 1)[0] }
+        loc.label.should == "Kernel#tap"
+      end
+
+      it "an instance method defined in Ruby" do
+        ThreadBacktraceLocationSpecs::INSTANCE.instance_method_location[0].label.should == "ThreadBacktraceLocationSpecs#instance_method_location"
+      end
+
+      it "a block in an instance method defined in Ruby" do
+        ThreadBacktraceLocationSpecs::INSTANCE.instance_block_location[0].label.should == "block in ThreadBacktraceLocationSpecs#instance_block_location"
+      end
+
+      it "a nested block in an instance method defined in Ruby" do
+        ThreadBacktraceLocationSpecs::INSTANCE.instance_locations_inside_nested_block[0].label.should == "block (2 levels) in ThreadBacktraceLocationSpecs#instance_locations_inside_nested_block"
+      end
+
+      it "a method defined via module_exec" do
+        ThreadBacktraceLocationSpecs.module_exec do
+          def in_module_exec
+            caller_locations(0)
+          end
+        end
+        ThreadBacktraceLocationSpecs::INSTANCE.in_module_exec[0].label.should == "ThreadBacktraceLocationSpecs#in_module_exec"
+      end
+
+      it "a method defined via module_eval" do
+        ThreadBacktraceLocationSpecs.module_eval <<~RUBY
+          def in_module_eval
+            caller_locations(0)
+          end
+        RUBY
+        ThreadBacktraceLocationSpecs::INSTANCE.in_module_eval[0].label.should == "ThreadBacktraceLocationSpecs#in_module_eval"
+      end
+    end
+
+    describe "is Module.method for" do
+      it "a singleton method defined in Ruby" do
+        ThreadBacktraceLocationSpecs.method_location[0].label.should == "ThreadBacktraceLocationSpecs.method_location"
+      end
+
+      it "a block in a singleton method defined in Ruby" do
+        ThreadBacktraceLocationSpecs.block_location[0].label.should == "block in ThreadBacktraceLocationSpecs.block_location"
+      end
+
+      it "a nested block in a singleton method defined in Ruby" do
+        ThreadBacktraceLocationSpecs.locations_inside_nested_blocks[2].label.should == "block (3 levels) in ThreadBacktraceLocationSpecs.locations_inside_nested_blocks"
+      end
+
+      it "a singleton method defined via def Const.method" do
+        def ThreadBacktraceLocationSpecs.def_singleton
+          caller_locations(0)
+        end
+        ThreadBacktraceLocationSpecs.def_singleton[0].label.should == "ThreadBacktraceLocationSpecs.def_singleton"
+      end
+    end
+
+    it "shows the original method name for an aliased method" do
+      ThreadBacktraceLocationSpecs::INSTANCE.aliased_method.should == "ThreadBacktraceLocationSpecs#original_method"
+    end
+
+    # A wide variety of cases.
+    # These show interesting cases when trying to determine the name statically/at parse time
+    describe "is correct for" do
+      base = ThreadBacktraceLocationSpecs
+
+      it "M::C#regular_instance_method" do
+        base::M::C.new.regular_instance_method.should == "#{base}::M::C#regular_instance_method"
+      end
+
+      it "M::C.sdef_class_method" do
+        base::M::C.sdef_class_method.should == "#{base}::M::C.sdef_class_method"
+      end
+
+      it "M::C.sclass_method" do
+        base::M::C.sclass_method.should == "#{base}::M::C.sclass_method"
+      end
+
+      it "M::C.block_in_sclass_method" do
+        base::M::C.block_in_sclass_method.should == "block (2 levels) in #{base}::M::C.block_in_sclass_method"
+      end
+
+      it "M::D#scoped_method" do
+        base::M::D.new.scoped_method.should == "#{base}::M::D#scoped_method"
+      end
+
+      it "M::D.sdef_scoped_method" do
+        base::M::D.sdef_scoped_method.should == "#{base}::M::D.sdef_scoped_method"
+      end
+
+      it "M::D.sclass_scoped_method" do
+        base::M::D.sclass_scoped_method.should == "#{base}::M::D.sclass_scoped_method"
+      end
+
+      it "ThreadBacktraceLocationSpecs#top" do
+        ThreadBacktraceLocationSpecs::INSTANCE.top.should == "ThreadBacktraceLocationSpecs#top"
+      end
+
+      it "ThreadBacktraceLocationSpecs::Nested#top_nested" do
+        ThreadBacktraceLocationSpecs::Nested.new.top_nested.should == "ThreadBacktraceLocationSpecs::Nested#top_nested"
+      end
+
+      it "ThreadBacktraceLocationSpecs::Nested::C#top_nested_c" do
+        ThreadBacktraceLocationSpecs::Nested::C.new.top_nested_c.should == "ThreadBacktraceLocationSpecs::Nested::C#top_nested_c"
+      end
+
+      it "Object#label_top_method" do
+        label_top_method.should == "Object#label_top_method"
+      end
+
+      it "main.label_sdef_method_of_main" do
+        main = TOPLEVEL_BINDING.receiver
+        main.label_sdef_method_of_main.should == "label_sdef_method_of_main"
+      end
+
+      it "main.label_sclass_method_of_main" do
+        main = TOPLEVEL_BINDING.receiver
+        main.label_sclass_method_of_main.should == "label_sclass_method_of_main"
+      end
+
+      it "unknown_def_singleton_method" do
+        base::SOME_OBJECT.unknown_def_singleton_method.should == "unknown_def_singleton_method"
+      end
+
+      it "unknown_sdef_singleton_method" do
+        base::SOME_OBJECT.unknown_sdef_singleton_method.should == "unknown_sdef_singleton_method"
+      end
+
+      it "M#module_eval_method" do
+        Object.new.extend(base::M).module_eval_method.should == "#{base}::M#module_eval_method"
+      end
+
+      it "M.sdef_module_eval_method" do
+        base::M.sdef_module_eval_method.should == "#{base}::M.sdef_module_eval_method"
+      end
+
+      it "ThreadBacktraceLocationSpecs.string_class_method" do
+        ThreadBacktraceLocationSpecs.string_class_method.should == "ThreadBacktraceLocationSpecs.string_class_method"
+      end
+
+      it "ThreadBacktraceLocationSpecs.nested_class_method" do
+        ThreadBacktraceLocationSpecs.nested_class_method.should == "ThreadBacktraceLocationSpecs.nested_class_method"
+      end
+
+      it "M#mod_function" do
+        Object.new.extend(base::M).send(:mod_function).should == "#{base}::M#mod_function"
+      end
+
+      it "M.mod_function" do
+        base::M.mod_function.should == "#{base}::M.mod_function"
+      end
+
+      it "sdef_expression" do
+        base.sdef_expression.should == "#{base}.sdef_expression"
+      end
+
+      it "block_in_sdef_expression" do
+        base.block_in_sdef_expression.should == "block in #{base}.block_in_sdef_expression"
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/lineno_spec.rb b/spec/ruby/core/thread/backtrace/location/lineno_spec.rb
index dc93d32d75..10457f80f0 100644
--- a/spec/ruby/core/thread/backtrace/location/lineno_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/lineno_spec.rb
@@ -7,7 +7,17 @@ describe 'Thread::Backtrace::Location#lineno' do
     @line  = __LINE__ - 1
   end
 
-  it 'returns the absolute path of the call frame' do
+  it 'returns the line number of the call frame' do
     @frame.lineno.should == @line
   end
+
+  it 'should be the same line number as in #to_s, including for core methods' do
+    # Get the caller_locations from a call made into a core library method
+    locations = [:non_empty].map { caller_locations }[0]
+
+    locations.each do |location|
+      line_number = location.to_s[/:(\d+):/, 1]
+      location.lineno.should == Integer(line_number)
+    end
+  end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/path_spec.rb b/spec/ruby/core/thread/backtrace/location/path_spec.rb
index b1a3439747..75f76833a9 100644
--- a/spec/ruby/core/thread/backtrace/location/path_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/path_spec.rb
@@ -41,7 +41,7 @@ describe 'Thread::Backtrace::Location#path' do
       context 'when using a relative script path' do
         it 'returns a path relative to the working directory' do
           path      = 'fixtures/main.rb'
-          directory = File.dirname(__FILE__)
+          directory = __dir__
           Dir.chdir(directory) {
             ruby_exe(path)
           }.should == path
@@ -86,4 +86,39 @@ describe 'Thread::Backtrace::Location#path' do
       end
     end
   end
+
+  it 'should be the same path as in #to_s, including for core methods' do
+    # Get the caller_locations from a call made into a core library method
+    locations = [:non_empty].map { caller_locations }[0]
+
+    locations.each do |location|
+      filename = location.to_s[/^(.+):\d+:/, 1]
+      path = location.path
+
+      path.should == filename
+    end
+  end
+
+  context "canonicalization" do
+    platform_is_not :windows do
+      before :each do
+        @file = fixture(__FILE__, "path.rb")
+        @symlink = tmp("symlink.rb")
+        File.symlink(@file, @symlink)
+        ScratchPad.record []
+      end
+
+      after :each do
+        rm_r @symlink
+      end
+
+      it "returns a non-canonical path with symlinks, the same as __FILE__" do
+        realpath = File.realpath(@symlink)
+        realpath.should_not == @symlink
+
+        load @symlink
+        ScratchPad.recorded.should == [@symlink, @symlink]
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/thread/backtrace/location/to_s_spec.rb b/spec/ruby/core/thread/backtrace/location/to_s_spec.rb
index 5911cdced0..983ce4c3f8 100644
--- a/spec/ruby/core/thread/backtrace/location/to_s_spec.rb
+++ b/spec/ruby/core/thread/backtrace/location/to_s_spec.rb
@@ -8,6 +8,6 @@ describe 'Thread::Backtrace::Location#to_s' do
   end
 
   it 'converts the call frame to a String' do
-    @frame.to_s.should include("#{__FILE__}:#{@line}:in ")
+    @frame.to_s.should.include?("#{__FILE__}:#{@line}:in ")
   end
 end
diff --git a/spec/ruby/core/thread/backtrace_locations_spec.rb b/spec/ruby/core/thread/backtrace_locations_spec.rb
index 66947f8ea6..28a488f311 100644
--- a/spec/ruby/core/thread/backtrace_locations_spec.rb
+++ b/spec/ruby/core/thread/backtrace_locations_spec.rb
@@ -3,20 +3,66 @@ require_relative '../../spec_helper'
 describe "Thread#backtrace_locations" do
   it "returns an Array" do
     locations = Thread.current.backtrace_locations
-    locations.should be_an_instance_of(Array)
-    locations.should_not be_empty
+    locations.should.instance_of?(Array)
+    locations.should_not.empty?
   end
 
   it "sets each element to a Thread::Backtrace::Location" do
     locations = Thread.current.backtrace_locations
-    locations.each { |loc| loc.should be_an_instance_of(Thread::Backtrace::Location) }
+    locations.each { |loc| loc.should.instance_of?(Thread::Backtrace::Location) }
   end
 
   it "can be called on any Thread" do
     locations = Thread.new { Thread.current.backtrace_locations }.value
-    locations.should be_an_instance_of(Array)
-    locations.should_not be_empty
-    locations.each { |loc| loc.should be_an_instance_of(Thread::Backtrace::Location) }
+    locations.should.instance_of?(Array)
+    locations.should_not.empty?
+    locations.each { |loc| loc.should.instance_of?(Thread::Backtrace::Location) }
+  end
+
+  it "can be called with a number of locations to omit" do
+    locations1 = Thread.current.backtrace_locations
+    locations2 = Thread.current.backtrace_locations(2)
+    locations2.length.should == locations1[2..-1].length
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+  end
+
+  it "can be called with a maximum number of locations to return as second parameter" do
+    locations1 = Thread.current.backtrace_locations
+    locations2 = Thread.current.backtrace_locations(2, 3)
+    locations2.map(&:to_s).should == locations1[2..4].map(&:to_s)
+  end
+
+  it "can be called with a range" do
+    locations1 = Thread.current.backtrace_locations
+    locations2 = Thread.current.backtrace_locations(2..4)
+    locations2.map(&:to_s).should == locations1[2..4].map(&:to_s)
+  end
+
+  it "can be called with a range whose end is negative" do
+    Thread.current.backtrace_locations(2..-1).map(&:to_s).should == Thread.current.backtrace_locations[2..-1].map(&:to_s)
+    Thread.current.backtrace_locations(2..-2).map(&:to_s).should == Thread.current.backtrace_locations[2..-2].map(&:to_s)
+  end
+
+  it "can be called with an endless range" do
+    locations1 = Thread.current.backtrace_locations(0)
+    locations2 = Thread.current.backtrace_locations(eval("(2..)"))
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
+  end
+
+  it "can be called with an beginless range" do
+    locations1 = Thread.current.backtrace_locations(0)
+    locations2 = Thread.current.backtrace_locations((..5))
+    locations2.map(&:to_s)[eval("(2..)")].should == locations1[(..5)].map(&:to_s)[eval("(2..)")]
+  end
+
+  it "returns nil if omitting more locations than available" do
+    Thread.current.backtrace_locations(100).should == nil
+    Thread.current.backtrace_locations(100..-1).should == nil
+  end
+
+  it "returns [] if omitting exactly the number of locations available" do
+    omit = Thread.current.backtrace_locations.length
+    Thread.current.backtrace_locations(omit).should == []
   end
 
   it "without argument is the same as showing all locations with 0..-1" do
@@ -24,7 +70,7 @@ describe "Thread#backtrace_locations" do
   end
 
   it "the first location reports the call to #backtrace_locations" do
-    Thread.current.backtrace_locations(0..0)[0].to_s.should == "#{__FILE__ }:#{__LINE__ }:in `backtrace_locations'"
+    Thread.current.backtrace_locations(0..0)[0].to_s.should =~ /\A#{__FILE__ }:#{__LINE__ }:in [`'](?:Thread#)?backtrace_locations'\z/
   end
 
   it "[1..-1] is the same as #caller_locations(0..-1) for Thread.current" do
diff --git a/spec/ruby/core/thread/backtrace_spec.rb b/spec/ruby/core/thread/backtrace_spec.rb
index 84ed574d5c..770c300f06 100644
--- a/spec/ruby/core/thread/backtrace_spec.rb
+++ b/spec/ruby/core/thread/backtrace_spec.rb
@@ -12,8 +12,8 @@ describe "Thread#backtrace" do
     Thread.pass while t.status && t.status != 'sleep'
 
     backtrace = t.backtrace
-    backtrace.should be_kind_of(Array)
-    backtrace.first.should =~ /`sleep'/
+    backtrace.should.is_a?(Array)
+    backtrace.first.should =~ /[`'](?:Kernel#)?sleep'/
 
     t.raise 'finish the thread'
     t.join
@@ -30,6 +30,40 @@ describe "Thread#backtrace" do
     backtrace = t.backtrace
     t.kill
     t.join
-    backtrace.should be_kind_of(Array)
+    backtrace.should.is_a?(Array)
+  end
+
+  it "can be called with a number of locations to omit" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2)
+    locations1[2..-1].length.should == locations2.length
+    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a maximum number of locations to return as second parameter" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2, 3)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2..4)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range whose end is negative" do
+    Thread.current.backtrace(2..-1).should == Thread.current.backtrace[2..-1]
+    Thread.current.backtrace(2..-2).should == Thread.current.backtrace[2..-2]
+  end
+
+  it "returns nil if omitting more locations than available" do
+    Thread.current.backtrace(100).should == nil
+    Thread.current.backtrace(100..-1).should == nil
+  end
+
+  it "returns [] if omitting exactly the number of locations available" do
+    omit = Thread.current.backtrace.length
+    Thread.current.backtrace(omit).should == []
   end
 end
diff --git a/spec/ruby/core/thread/current_spec.rb b/spec/ruby/core/thread/current_spec.rb
index f5ed1d95cd..f893f078ba 100644
--- a/spec/ruby/core/thread/current_spec.rb
+++ b/spec/ruby/core/thread/current_spec.rb
@@ -4,13 +4,13 @@ require_relative 'fixtures/classes'
 describe "Thread.current" do
   it "returns a thread" do
     current = Thread.current
-    current.should be_kind_of(Thread)
+    current.should.is_a?(Thread)
   end
 
   it "returns the current thread" do
     t = Thread.new { Thread.current }
-    t.value.should equal(t)
-    Thread.current.should_not equal(t.value)
+    t.value.should.equal?(t)
+    Thread.current.should_not.equal?(t.value)
   end
 
   it "returns the correct thread in a Fiber" do
@@ -22,10 +22,10 @@ describe "Thread.current" do
         cur = Thread.current
         Fiber.new {
           Thread.current
-        }.resume.should equal cur
+        }.resume.should.equal? cur
         cur
       }
-      t.value.should equal t
+      t.value.should.equal? t
     end
   end
 end
diff --git a/spec/ruby/core/thread/each_caller_location_spec.rb b/spec/ruby/core/thread/each_caller_location_spec.rb
new file mode 100644
index 0000000000..15fda1a37b
--- /dev/null
+++ b/spec/ruby/core/thread/each_caller_location_spec.rb
@@ -0,0 +1,47 @@
+require_relative '../../spec_helper'
+
+describe "Thread.each_caller_location" do
+  it "iterates through the current execution stack and matches caller_locations content and type" do
+    ScratchPad.record []
+    Thread.each_caller_location { |l| ScratchPad << l; }
+
+    ScratchPad.recorded.map(&:to_s).should == caller_locations.map(&:to_s)
+    ScratchPad.recorded[0].should.is_a?(Thread::Backtrace::Location)
+  end
+
+  it "returns subset of 'Thread.to_enum(:each_caller_location)' locations" do
+    ar = []
+    ecl = Thread.each_caller_location { |x| ar << x }
+
+    (ar.map(&:to_s) - Thread.to_enum(:each_caller_location).to_a.map(&:to_s)).should.empty?
+  end
+
+  it "stops the backtrace iteration if 'break' occurs" do
+    i = 0
+    ar = []
+    ecl = Thread.each_caller_location do |x|
+      ar << x
+      i += 1
+      break x if i == 2
+    end
+
+    ar.map(&:to_s).should == caller_locations(1, 2).map(&:to_s)
+    ecl.should.is_a?(Thread::Backtrace::Location)
+  end
+
+  it "returns nil" do
+    Thread.each_caller_location {}.should == nil
+  end
+
+  it "raises LocalJumpError when called without a block" do
+    -> {
+      Thread.each_caller_location
+    }.should.raise(LocalJumpError, "no block given")
+  end
+
+  it "doesn't accept keyword arguments" do
+    -> {
+      Thread.each_caller_location(12, foo: 10) {}
+    }.should.raise(ArgumentError);
+  end
+end
diff --git a/spec/ruby/core/thread/element_reference_spec.rb b/spec/ruby/core/thread/element_reference_spec.rb
index 85280cb287..72892f6c50 100644
--- a/spec/ruby/core/thread/element_reference_spec.rb
+++ b/spec/ruby/core/thread/element_reference_spec.rb
@@ -37,8 +37,19 @@ describe "Thread#[]" do
     t2["value"].should == 2
   end
 
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('value')
+    key.should_receive(:to_str).and_return('value')
+
+    th = Thread.new do
+      Thread.current[:value] = 1
+    end.join
+
+    th[key].should == 1
+  end
+
   it "raises exceptions on the wrong type of keys" do
-    -> { Thread.current[nil] }.should raise_error(TypeError)
-    -> { Thread.current[5] }.should raise_error(TypeError)
+    -> { Thread.current[nil] }.should.raise(TypeError)
+    -> { Thread.current[5] }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/core/thread/element_set_spec.rb b/spec/ruby/core/thread/element_set_spec.rb
index d974b5e1c7..97d6c23980 100644
--- a/spec/ruby/core/thread/element_set_spec.rb
+++ b/spec/ruby/core/thread/element_set_spec.rb
@@ -6,19 +6,42 @@ describe "Thread#[]=" do
     Thread.current[:value] = nil
   end
 
-  it "raises a #{frozen_error_class} if the thread is frozen" do
+  it "raises a FrozenError if the thread is frozen" do
     Thread.new do
       th = Thread.current
       th.freeze
       -> {
         th[:foo] = "bar"
-      }.should raise_error(frozen_error_class, /frozen/)
+      }.should.raise(FrozenError, "can't modify frozen thread locals")
     end.join
   end
 
+  it "accepts Strings and Symbols" do
+    t1 = Thread.new do
+      Thread.current[:value] = 1
+    end.join
+    t2 = Thread.new do
+      Thread.current["value"] = 2
+    end.join
+
+    t1[:value].should == 1
+    t2[:value].should == 2
+  end
+
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('value')
+    key.should_receive(:to_str).and_return('value')
+
+    th = Thread.new do
+      Thread.current[key] = 1
+    end.join
+
+    th[:value].should == 1
+  end
+
   it "raises exceptions on the wrong type of keys" do
-    -> { Thread.current[nil] = true }.should raise_error(TypeError)
-    -> { Thread.current[5] = true }.should raise_error(TypeError)
+    -> { Thread.current[nil] = true }.should.raise(TypeError)
+    -> { Thread.current[5] = true }.should.raise(TypeError)
   end
 
   it "is not shared across fibers" do
@@ -28,7 +51,7 @@ describe "Thread#[]=" do
       Thread.current[:value].should == 1
     end
     fib.resume
-    Thread.current[:value].should be_nil
+    Thread.current[:value].should == nil
     Thread.current[:value] = 2
     fib.resume
     Thread.current[:value] = 2
diff --git a/spec/ruby/core/thread/exclusive_spec.rb b/spec/ruby/core/thread/exclusive_spec.rb
deleted file mode 100644
index ec35ba542b..0000000000
--- a/spec/ruby/core/thread/exclusive_spec.rb
+++ /dev/null
@@ -1,49 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "Thread.exclusive" do
-  verbose = Object
-
-  before :each do
-    ScratchPad.clear
-    verbose, $VERBOSE = $VERBOSE, nil
-  end
-
-  after :each do
-    $VERBOSE = verbose
-  end
-
-  it "yields to the block" do
-    Thread.exclusive { ScratchPad.record true }
-    ScratchPad.recorded.should == true
-  end
-
-  it "returns the result of yielding" do
-    Thread.exclusive { :result }.should == :result
-  end
-
-  it "blocks the caller if another thread is also in an exclusive block" do
-    m = Mutex.new
-    q1 = Queue.new
-    q2 = Queue.new
-
-    t = Thread.new {
-      Thread.exclusive {
-        q1.push :ready
-        q2.pop
-      }
-    }
-
-    q1.pop.should == :ready
-
-    -> { Thread.exclusive { } }.should block_caller
-
-    q2.push :done
-    t.join
-  end
-
-  it "is not recursive" do
-    Thread.exclusive do
-      -> { Thread.exclusive { } }.should raise_error(ThreadError)
-    end
-  end
-end
diff --git a/spec/ruby/core/thread/exit_spec.rb b/spec/ruby/core/thread/exit_spec.rb
index c3f710920e..b2e923c680 100644
--- a/spec/ruby/core/thread/exit_spec.rb
+++ b/spec/ruby/core/thread/exit_spec.rb
@@ -10,6 +10,6 @@ describe "Thread.exit" do
   it "causes the current thread to exit" do
     thread = Thread.new { Thread.exit; sleep }
     thread.join
-    thread.status.should be_false
+    thread.status.should == false
   end
 end
diff --git a/spec/ruby/core/thread/fetch_spec.rb b/spec/ruby/core/thread/fetch_spec.rb
index d71c938880..fe27dec4a2 100644
--- a/spec/ruby/core/thread/fetch_spec.rb
+++ b/spec/ruby/core/thread/fetch_spec.rb
@@ -1,38 +1,66 @@
 require_relative '../../spec_helper'
 
-ruby_version_is '2.5' do
-  describe 'Thread#fetch' do
-    describe 'with 2 arguments' do
-      it 'returns the value of the fiber-local variable if value has been assigned' do
-        th = Thread.new { Thread.current[:cat] = 'meow' }
-        th.join
-        th.fetch(:cat, true).should == 'meow'
-      end
-
-      it "returns the default value if fiber-local variable hasn't been assigned" do
-        th = Thread.new {}
-        th.join
-        th.fetch(:cat, true).should == true
-      end
-    end
-
-    describe 'with 1 argument' do
-      it 'raises a KeyError when the Thread does not have a fiber-local variable of the same name' do
-        th = Thread.new {}
-        th.join
-        -> { th.fetch(:cat) }.should raise_error(KeyError)
-      end
-
-      it 'returns the value of the fiber-local variable if value has been assigned' do
-        th = Thread.new { Thread.current[:cat] = 'meow' }
-        th.join
-        th.fetch(:cat).should == 'meow'
-      end
-    end
-
-    it 'raises an ArgumentError when not passed one or two arguments' do
-      -> { Thread.current.fetch() }.should raise_error(ArgumentError)
-      -> { Thread.current.fetch(1, 2, 3) }.should raise_error(ArgumentError)
+describe 'Thread#fetch' do
+  describe 'with 2 arguments' do
+    it 'returns the value of the fiber-local variable if value has been assigned' do
+      th = Thread.new { Thread.current[:cat] = 'meow' }
+      th.join
+      th.fetch(:cat, true).should == 'meow'
     end
+
+    it "returns the default value if fiber-local variable hasn't been assigned" do
+      th = Thread.new {}
+      th.join
+      th.fetch(:cat, true).should == true
+    end
+  end
+
+  describe 'with 1 argument' do
+    it 'raises a KeyError when the Thread does not have a fiber-local variable of the same name' do
+      th = Thread.new {}
+      th.join
+      -> { th.fetch(:cat) }.should.raise(KeyError)
+    end
+
+    it 'returns the value of the fiber-local variable if value has been assigned' do
+      th = Thread.new { Thread.current[:cat] = 'meow' }
+      th.join
+      th.fetch(:cat).should == 'meow'
+    end
+  end
+
+  describe 'with a block' do
+    it 'returns the value of the fiber-local variable if value has been assigned' do
+      th = Thread.new { Thread.current[:cat] = 'meow' }
+      th.join
+      th.fetch(:cat) { true }.should == 'meow'
+    end
+
+    it "returns the block value if fiber-local variable hasn't been assigned" do
+      th = Thread.new {}
+      th.join
+      th.fetch(:cat) { true }.should == true
+    end
+
+    it "does not call the block if value has been assigned" do
+      th = Thread.new { Thread.current[:cat] = 'meow' }
+      th.join
+      var = :not_updated
+      th.fetch(:cat) { var = :updated }.should == 'meow'
+      var.should == :not_updated
+    end
+
+    it "uses the block if a default is given and warns about it" do
+      th = Thread.new {}
+      th.join
+      -> {
+        th.fetch(:cat, false) { true }.should == true
+      }.should complain(/warning: block supersedes default value argument/)
+    end
+  end
+
+  it 'raises an ArgumentError when not passed one or two arguments' do
+    -> { Thread.current.fetch() }.should.raise(ArgumentError)
+    -> { Thread.current.fetch(1, 2, 3) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/thread/fixtures/classes.rb b/spec/ruby/core/thread/fixtures/classes.rb
index c1f15935ee..14d5d2f7bf 100644
--- a/spec/ruby/core/thread/fixtures/classes.rb
+++ b/spec/ruby/core/thread/fixtures/classes.rb
@@ -6,12 +6,38 @@ module ThreadSpecs
     end
   end
 
+  class NewThreadToRaise
+    def self.raise(*args, **kwargs, &block)
+      thread = Thread.new do
+        Thread.current.report_on_exception = false
+
+        if block_given?
+          block.call do
+            sleep
+          end
+        else
+          sleep
+        end
+      end
+
+      Thread.pass until thread.stop?
+
+      thread.raise(*args, **kwargs)
+
+      thread.join
+    ensure
+      thread.kill if thread.alive?
+      Thread.pass while thread.alive? # Thread#kill may not terminate a thread immediately so it may be detected as a leaked one
+    end
+  end
+
   class Status
-    attr_reader :thread, :inspect, :status
+    attr_reader :thread, :inspect, :status, :to_s
     def initialize(thread)
       @thread = thread
       @alive = thread.alive?
       @inspect = thread.inspect
+      @to_s = thread.to_s
       @status = thread.status
       @stop = thread.stop?
     end
@@ -181,7 +207,7 @@ module ThreadSpecs
 
   def self.join_dying_thread_with_outer_ensure(kill_method_name=:kill)
     t = dying_thread_with_outer_ensure(kill_method_name) { yield }
-    -> { t.join }.should raise_error(RuntimeError, "In dying thread")
+    -> { t.join }.should.raise(RuntimeError, "In dying thread")
     return t
   end
 
diff --git a/spec/ruby/core/thread/group_spec.rb b/spec/ruby/core/thread/group_spec.rb
index 59f5ac37c8..d0d4704b66 100644
--- a/spec/ruby/core/thread/group_spec.rb
+++ b/spec/ruby/core/thread/group_spec.rb
@@ -1,5 +1,16 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
+
 describe "Thread#group" do
-  it "needs to be reviewed for spec completeness"
+  it "returns the default thread group for the main thread" do
+    Thread.main.group.should == ThreadGroup::Default
+  end
+
+  it "returns the thread group explicitly set for this thread" do
+    thread = Thread.new { nil }
+    thread_group = ThreadGroup.new
+    thread_group.add(thread)
+    thread.group.should == thread_group
+  ensure
+    thread.join if thread
+  end
 end
diff --git a/spec/ruby/core/thread/handle_interrupt_spec.rb b/spec/ruby/core/thread/handle_interrupt_spec.rb
new file mode 100644
index 0000000000..aa03d4c66d
--- /dev/null
+++ b/spec/ruby/core/thread/handle_interrupt_spec.rb
@@ -0,0 +1,125 @@
+require_relative '../../spec_helper'
+
+describe "Thread.handle_interrupt" do
+  def make_handle_interrupt_thread(interrupt_config, blocking = true)
+    interrupt_class = Class.new(RuntimeError)
+
+    ScratchPad.record []
+
+    in_handle_interrupt = Queue.new
+    can_continue = Queue.new
+
+    thread = Thread.new do
+      begin
+        Thread.handle_interrupt(interrupt_config) do
+          begin
+            in_handle_interrupt << true
+            if blocking
+              Thread.pass # Make it clearer the other thread needs to wait for this one to be in #pop
+              can_continue.pop
+            else
+              begin
+                can_continue.pop(true)
+              rescue ThreadError
+                Thread.pass
+                retry
+              end
+            end
+          rescue interrupt_class
+            ScratchPad << :interrupted
+          end
+        end
+      rescue interrupt_class
+        ScratchPad << :deferred
+      end
+    end
+
+    in_handle_interrupt.pop
+    if blocking
+      # Ensure the thread is inside Thread#pop, as if thread.raise is done before it would be deferred
+      Thread.pass until thread.stop?
+    end
+    thread.raise interrupt_class, "interrupt"
+    can_continue << true
+    thread.join
+
+    ScratchPad.recorded
+  end
+
+  before :each do
+    Thread.pending_interrupt?.should == false # sanity check
+  end
+
+  it "with :never defers interrupts until exiting the handle_interrupt block" do
+    make_handle_interrupt_thread(RuntimeError => :never).should == [:deferred]
+  end
+
+  it "with :on_blocking defers interrupts until the next blocking call" do
+    make_handle_interrupt_thread(RuntimeError => :on_blocking).should == [:interrupted]
+    make_handle_interrupt_thread({ RuntimeError => :on_blocking }, false).should == [:deferred]
+  end
+
+  it "with :immediate handles interrupts immediately" do
+    make_handle_interrupt_thread(RuntimeError => :immediate).should == [:interrupted]
+  end
+
+  it "with :immediate immediately runs pending interrupts, before the block" do
+    Thread.handle_interrupt(RuntimeError => :never) do
+      current = Thread.current
+      Thread.new {
+        current.raise "interrupt immediate"
+      }.join
+
+      Thread.pending_interrupt?.should == true
+      -> {
+        Thread.handle_interrupt(RuntimeError => :immediate) {
+          flunk "not reached"
+        }
+      }.should.raise(RuntimeError, "interrupt immediate")
+      Thread.pending_interrupt?.should == false
+    end
+  end
+
+  it "also works with suspended Fibers and does not duplicate interrupts" do
+    fiber = Fiber.new { Fiber.yield }
+    fiber.resume
+
+    Thread.handle_interrupt(RuntimeError => :never) do
+      current = Thread.current
+      Thread.new {
+        current.raise "interrupt with fibers"
+      }.join
+
+      Thread.pending_interrupt?.should == true
+      -> {
+        Thread.handle_interrupt(RuntimeError => :immediate) {
+          flunk "not reached"
+        }
+      }.should.raise(RuntimeError, "interrupt with fibers")
+      Thread.pending_interrupt?.should == false
+    end
+
+    fiber.resume
+  end
+
+  it "runs pending interrupts at the end of the block, even if there was an exception raised in the block" do
+    executed = false
+    -> {
+      Thread.handle_interrupt(RuntimeError => :never) do
+        current = Thread.current
+        Thread.new {
+          current.raise "interrupt exception"
+        }.join
+
+        Thread.pending_interrupt?.should == true
+        executed = true
+        raise "regular exception"
+      end
+    }.should.raise(RuntimeError, "interrupt exception")
+    executed.should == true
+  end
+
+  it "supports multiple pairs in the Hash" do
+    make_handle_interrupt_thread(ArgumentError => :never, RuntimeError => :never).should == [:deferred]
+  end
+end
diff --git a/spec/ruby/core/thread/ignore_deadlock_spec.rb b/spec/ruby/core/thread/ignore_deadlock_spec.rb
new file mode 100644
index 0000000000..b48bc9f9b0
--- /dev/null
+++ b/spec/ruby/core/thread/ignore_deadlock_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+
+describe "Thread.ignore_deadlock" do
+  it "returns false by default" do
+    Thread.ignore_deadlock.should == false
+  end
+end
+
+describe "Thread.ignore_deadlock=" do
+  it "changes the value of Thread.ignore_deadlock" do
+    ignore_deadlock = Thread.ignore_deadlock
+    Thread.ignore_deadlock = true
+    begin
+      Thread.ignore_deadlock.should == true
+    ensure
+      Thread.ignore_deadlock = ignore_deadlock
+    end
+  end
+end
diff --git a/spec/ruby/core/thread/initialize_spec.rb b/spec/ruby/core/thread/initialize_spec.rb
index 4fca900cd8..b9a94560ee 100644
--- a/spec/ruby/core/thread/initialize_spec.rb
+++ b/spec/ruby/core/thread/initialize_spec.rb
@@ -19,7 +19,7 @@ describe "Thread#initialize" do
         @t.instance_eval do
           initialize {}
         end
-      }.should raise_error(ThreadError)
+      }.should.raise(ThreadError)
     end
 
   end
diff --git a/spec/ruby/core/thread/inspect_spec.rb b/spec/ruby/core/thread/inspect_spec.rb
index 4c635b7aaa..bd6e0c31fc 100644
--- a/spec/ruby/core/thread/inspect_spec.rb
+++ b/spec/ruby/core/thread/inspect_spec.rb
@@ -1,44 +1,6 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
+require_relative 'shared/to_s'
 
 describe "Thread#inspect" do
-  it "can check it's own status" do
-    ThreadSpecs.status_of_current_thread.inspect.should include('run')
-  end
-
-  it "describes a running thread" do
-    ThreadSpecs.status_of_running_thread.inspect.should include('run')
-  end
-
-  it "describes a sleeping thread" do
-    ThreadSpecs.status_of_sleeping_thread.inspect.should include('sleep')
-  end
-
-  it "describes a blocked thread" do
-    ThreadSpecs.status_of_blocked_thread.inspect.should include('sleep')
-  end
-
-  it "describes a completed thread" do
-    ThreadSpecs.status_of_completed_thread.inspect.should include('dead')
-  end
-
-  it "describes a killed thread" do
-    ThreadSpecs.status_of_killed_thread.inspect.should include('dead')
-  end
-
-  it "describes a thread with an uncaught exception" do
-    ThreadSpecs.status_of_thread_with_uncaught_exception.inspect.should include('dead')
-  end
-
-  it "describes a dying sleeping thread" do
-    ThreadSpecs.status_of_dying_sleeping_thread.inspect.should include('sleep')
-  end
-
-  it "reports aborting on a killed thread" do
-    ThreadSpecs.status_of_dying_running_thread.inspect.should include('aborting')
-  end
-
-  it "reports aborting on a killed thread after sleep" do
-    ThreadSpecs.status_of_dying_thread_after_sleep.inspect.should include('aborting')
-  end
+  it_behaves_like :thread_to_s, :inspect
 end
diff --git a/spec/ruby/core/thread/join_spec.rb b/spec/ruby/core/thread/join_spec.rb
index f3c5cdc1ed..f4332167f1 100644
--- a/spec/ruby/core/thread/join_spec.rb
+++ b/spec/ruby/core/thread/join_spec.rb
@@ -4,23 +4,28 @@ require_relative 'fixtures/classes'
 describe "Thread#join" do
   it "returns the thread when it is finished" do
     t = Thread.new {}
-    t.join.should equal(t)
+    t.join.should.equal?(t)
   end
 
   it "returns the thread when it is finished when given a timeout" do
     t = Thread.new {}
     t.join
-    t.join(0).should equal(t)
+    t.join(0).should.equal?(t)
   end
 
   it "coerces timeout to a Float if it is not nil" do
     t = Thread.new {}
     t.join
-    t.join(0).should equal(t)
-    t.join(0.0).should equal(t)
-    t.join(nil).should equal(t)
-    -> { t.join(:foo) }.should raise_error TypeError
-    -> { t.join("bar") }.should raise_error TypeError
+    t.join(0).should.equal?(t)
+    t.join(0.0).should.equal?(t)
+    t.join(nil).should.equal?(t)
+  end
+
+  it "raises TypeError if the argument is not a valid timeout" do
+    t = Thread.new { }
+    t.join
+    -> { t.join(:foo) }.should.raise TypeError
+    -> { t.join("bar") }.should.raise TypeError
   end
 
   it "returns nil if it is not finished when given a timeout" do
@@ -50,16 +55,16 @@ describe "Thread#join" do
       Thread.current.report_on_exception = false
       raise NotImplementedError.new("Just kidding")
     }
-    -> { t.join }.should raise_error(NotImplementedError)
+    -> { t.join }.should.raise(NotImplementedError)
   end
 
   it "returns the dead thread" do
     t = Thread.new { Thread.current.kill }
-    t.join.should equal(t)
+    t.join.should.equal?(t)
   end
 
   it "raises any uncaught exception encountered in ensure block" do
     t = ThreadSpecs.dying_thread_ensures { raise NotImplementedError.new("Just kidding") }
-    -> { t.join }.should raise_error(NotImplementedError)
+    -> { t.join }.should.raise(NotImplementedError)
   end
 end
diff --git a/spec/ruby/core/thread/key_spec.rb b/spec/ruby/core/thread/key_spec.rb
index 6940cf5f28..a14aeb8d31 100644
--- a/spec/ruby/core/thread/key_spec.rb
+++ b/spec/ruby/core/thread/key_spec.rb
@@ -16,31 +16,38 @@ describe "Thread#key?" do
     @th.key?(:stanley.to_s).should == false
   end
 
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('key')
+    key.should_receive(:to_str).and_return('oliver')
+
+    @th.key?(key).should == true
+  end
+
   it "raises exceptions on the wrong type of keys" do
-    -> { Thread.current.key? nil }.should raise_error(TypeError)
-    -> { Thread.current.key? 5 }.should raise_error(TypeError)
+    -> { Thread.current.key? nil }.should.raise(TypeError)
+    -> { Thread.current.key? 5 }.should.raise(TypeError)
   end
 
   it "is not shared across fibers" do
     fib = Fiber.new do
       Thread.current[:val1] = 1
       Fiber.yield
-      Thread.current.key?(:val1).should be_true
-      Thread.current.key?(:val2).should be_false
+      Thread.current.key?(:val1).should == true
+      Thread.current.key?(:val2).should == false
     end
-    Thread.current.key?(:val1).should_not be_true
+    Thread.current.key?(:val1).should_not == true
     fib.resume
     Thread.current[:val2] = 2
     fib.resume
-    Thread.current.key?(:val1).should be_false
-    Thread.current.key?(:val2).should be_true
+    Thread.current.key?(:val1).should == false
+    Thread.current.key?(:val2).should == true
   end
 
   it "stores a local in another thread when in a fiber" do
     fib = Fiber.new do
       t = Thread.new do
         sleep
-        Thread.current.key?(:value).should be_true
+        Thread.current.key?(:value).should == true
       end
 
       Thread.pass while t.status and t.status != "sleep"
diff --git a/spec/ruby/core/thread/keys_spec.rb b/spec/ruby/core/thread/keys_spec.rb
index 15efda51d6..3a2edd2456 100644
--- a/spec/ruby/core/thread/keys_spec.rb
+++ b/spec/ruby/core/thread/keys_spec.rb
@@ -16,22 +16,22 @@ describe "Thread#keys" do
     fib = Fiber.new do
       Thread.current[:val1] = 1
       Fiber.yield
-      Thread.current.keys.should include(:val1)
-      Thread.current.keys.should_not include(:val2)
+      Thread.current.keys.should.include?(:val1)
+      Thread.current.keys.should_not.include?(:val2)
     end
-    Thread.current.keys.should_not include(:val1)
+    Thread.current.keys.should_not.include?(:val1)
     fib.resume
     Thread.current[:val2] = 2
     fib.resume
-    Thread.current.keys.should include(:val2)
-    Thread.current.keys.should_not include(:val1)
+    Thread.current.keys.should.include?(:val2)
+    Thread.current.keys.should_not.include?(:val1)
   end
 
   it "stores a local in another thread when in a fiber" do
     fib = Fiber.new do
       t = Thread.new do
         sleep
-        Thread.current.keys.should include(:value)
+        Thread.current.keys.should.include?(:value)
       end
 
       Thread.pass while t.status and t.status != "sleep"
diff --git a/spec/ruby/core/thread/kill_spec.rb b/spec/ruby/core/thread/kill_spec.rb
index f932bf5232..f9f1f46744 100644
--- a/spec/ruby/core/thread/kill_spec.rb
+++ b/spec/ruby/core/thread/kill_spec.rb
@@ -9,17 +9,13 @@ platform_is_not :mingw do
     it_behaves_like :thread_exit, :kill
   end
 
-  describe "Thread#kill!" do
-    it "needs to be reviewed for spec completeness"
-  end
-
   describe "Thread.kill" do
     it "causes the given thread to exit" do
       thread = Thread.new { sleep }
       Thread.pass while thread.status and thread.status != "sleep"
       Thread.kill(thread).should == thread
       thread.join
-      thread.status.should be_false
+      thread.status.should == false
     end
   end
 end
diff --git a/spec/ruby/core/thread/list_spec.rb b/spec/ruby/core/thread/list_spec.rb
index a0bf831856..5036841d58 100644
--- a/spec/ruby/core/thread/list_spec.rb
+++ b/spec/ruby/core/thread/list_spec.rb
@@ -3,15 +3,15 @@ require_relative 'fixtures/classes'
 
 describe "Thread.list" do
   it "includes the current and main thread" do
-    Thread.list.should include(Thread.current)
-    Thread.list.should include(Thread.main)
+    Thread.list.should.include?(Thread.current)
+    Thread.list.should.include?(Thread.main)
   end
 
   it "includes threads of non-default thread groups" do
     t = Thread.new { sleep }
     begin
       ThreadGroup.new.add(t)
-      Thread.list.should include(t)
+      Thread.list.should.include?(t)
     ensure
       t.kill
       t.join
@@ -21,7 +21,7 @@ describe "Thread.list" do
   it "does not include deceased threads" do
     t = Thread.new { 1; }
     t.join
-    Thread.list.should_not include(t)
+    Thread.list.should_not.include?(t)
   end
 
   it "includes waiting threads" do
@@ -29,7 +29,7 @@ describe "Thread.list" do
     t = Thread.new { q.pop }
     begin
       Thread.pass while t.status and t.status != 'sleep'
-      Thread.list.should include(t)
+      Thread.list.should.include?(t)
     ensure
       q << nil
       t.join
@@ -43,11 +43,11 @@ describe "Thread.list" do
       end
     end
 
-    while spawner.alive?
+    begin
       Thread.list.each { |th|
-        th.should be_kind_of(Thread)
+        th.should.is_a?(Thread)
       }
-    end
+    end while spawner.alive?
 
     threads = spawner.value
     threads.each(&:join)
diff --git a/spec/ruby/core/thread/name_spec.rb b/spec/ruby/core/thread/name_spec.rb
index 9b3d2f4b09..47d807be4d 100644
--- a/spec/ruby/core/thread/name_spec.rb
+++ b/spec/ruby/core/thread/name_spec.rb
@@ -36,7 +36,7 @@ describe "Thread#name=" do
   it "raises an ArgumentError if the name includes a null byte" do
     -> {
       @thread.name = "new thread\0name"
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "can be reset to nil" do
diff --git a/spec/ruby/core/thread/native_thread_id_spec.rb b/spec/ruby/core/thread/native_thread_id_spec.rb
new file mode 100644
index 0000000000..cc72e0b853
--- /dev/null
+++ b/spec/ruby/core/thread/native_thread_id_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../../spec_helper'
+
+platform_is :linux, :darwin, :windows, :freebsd do
+  describe "Thread#native_thread_id" do
+    it "returns an integer when the thread is alive" do
+      Thread.current.native_thread_id.should.is_a?(Integer)
+    end
+
+    it "returns nil when the thread is not running" do
+      t = Thread.new {}
+      t.join
+      t.native_thread_id.should == nil
+    end
+
+    it "each thread has different native thread id" do
+      t = Thread.new { sleep }
+      Thread.pass until t.stop?
+      main_thread_id = Thread.current.native_thread_id
+      t_thread_id = t.native_thread_id
+
+      # native_thread_id can be nil on a M:N scheduler
+      t_thread_id.should.is_a?(Integer) if t_thread_id != nil
+
+      main_thread_id.should_not == t_thread_id
+
+      t.run
+      t.join
+      t.native_thread_id.should == nil
+    end
+  end
+end
diff --git a/spec/ruby/core/thread/new_spec.rb b/spec/ruby/core/thread/new_spec.rb
index 3a57149381..acb6cd4e30 100644
--- a/spec/ruby/core/thread/new_spec.rb
+++ b/spec/ruby/core/thread/new_spec.rb
@@ -18,7 +18,7 @@ describe "Thread.new" do
   end
 
   it "raises an exception when not given a block" do
-    -> { Thread.new }.should raise_error(ThreadError)
+    -> { Thread.new }.should.raise(ThreadError)
   end
 
   it "creates a subclass of thread calls super with a block in initialize" do
@@ -36,7 +36,7 @@ describe "Thread.new" do
 
     -> {
       c.new
-    }.should raise_error(ThreadError)
+    }.should.raise(ThreadError)
   end
 
   it "calls and respects #initialize for the block to use" do
@@ -58,13 +58,13 @@ describe "Thread.new" do
     m2 = Mutex.new
     t = Thread.new {
       m1.lock
-      m1.locked?.should == true
+      m1.should.locked?
       m2.lock
-      m2.locked?.should == true
+      m2.should.locked?
     }
     t.join
-    m1.locked?.should == false
-    m2.locked?.should == false
+    m1.should_not.locked?
+    m2.should_not.locked?
   end
 
   it "releases Mutexes held by the Thread when the Thread finishes, also with Mutex#synchronize" do
@@ -75,9 +75,9 @@ describe "Thread.new" do
         m.lock
       }
       m.lock
-      m.locked?.should == true
+      m.should.locked?
     }
     t.join
-    m.locked?.should == false
+    m.should_not.locked?
   end
 end
diff --git a/spec/ruby/core/thread/pending_interrupt_spec.rb b/spec/ruby/core/thread/pending_interrupt_spec.rb
new file mode 100644
index 0000000000..5fbe7422a9
--- /dev/null
+++ b/spec/ruby/core/thread/pending_interrupt_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../spec_helper'
+
+describe "Thread.pending_interrupt?" do
+  it "returns false if there are no pending interrupts, e.g., outside any Thread.handle_interrupt block" do
+    Thread.pending_interrupt?.should == false
+  end
+
+  it "returns true if there are pending interrupts, e.g., Thread#raise inside Thread.handle_interrupt" do
+    executed = false
+    -> {
+      Thread.handle_interrupt(RuntimeError => :never) do
+        Thread.pending_interrupt?.should == false
+
+        current = Thread.current
+        Thread.new {
+          current.raise "interrupt"
+        }.join
+
+        Thread.pending_interrupt?.should == true
+        executed = true
+      end
+    }.should.raise(RuntimeError, "interrupt")
+    executed.should == true
+    Thread.pending_interrupt?.should == false
+  end
+end
+
+describe "Thread#pending_interrupt?" do
+  it "returns whether the given threads has pending interrupts" do
+    Thread.current.pending_interrupt?.should == false
+  end
+end
diff --git a/spec/ruby/core/thread/priority_spec.rb b/spec/ruby/core/thread/priority_spec.rb
index e13ad478b5..970f7f9971 100644
--- a/spec/ruby/core/thread/priority_spec.rb
+++ b/spec/ruby/core/thread/priority_spec.rb
@@ -15,19 +15,19 @@ describe "Thread#priority" do
   end
 
   it "inherits the priority of the current thread while running" do
-    @thread.alive?.should be_true
+    @thread.alive?.should == true
     @thread.priority.should == @current_priority
   end
 
   it "maintain the priority of the current thread after death" do
     ThreadSpecs.state = :exit
     @thread.join
-    @thread.alive?.should be_false
+    @thread.alive?.should == false
     @thread.priority.should == @current_priority
   end
 
   it "returns an integer" do
-    @thread.priority.should be_kind_of(Integer)
+    @thread.priority.should.is_a?(Integer)
   end
 end
 
@@ -59,7 +59,7 @@ describe "Thread#priority=" do
 
   describe "when set with a non-integer" do
     it "raises a type error" do
-      ->{ @thread.priority = Object.new }.should raise_error(TypeError)
+      ->{ @thread.priority = Object.new }.should.raise(TypeError)
     end
   end
 
diff --git a/spec/ruby/core/thread/raise_spec.rb b/spec/ruby/core/thread/raise_spec.rb
index 38571854ef..efc09d4a35 100644
--- a/spec/ruby/core/thread/raise_spec.rb
+++ b/spec/ruby/core/thread/raise_spec.rb
@@ -3,6 +3,16 @@ require_relative 'fixtures/classes'
 require_relative '../../shared/kernel/raise'
 
 describe "Thread#raise" do
+  it "is a public method" do
+    Thread.public_instance_methods.should.include?(:raise)
+  end
+
+  it_behaves_like :kernel_raise, :raise, ThreadSpecs::NewThreadToRaise
+  it_behaves_like :kernel_raise_across_contexts, :raise, ThreadSpecs::NewThreadToRaise
+  ruby_version_is "4.0" do
+    it_behaves_like :kernel_raise_with_cause, :raise, ThreadSpecs::NewThreadToRaise
+  end
+
   it "ignores dead threads and returns nil" do
     t = Thread.new { :dead }
     Thread.pass while t.alive?
@@ -26,27 +36,27 @@ describe "Thread#raise on a sleeping thread" do
   it "raises a RuntimeError if no exception class is given" do
     @thr.raise
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(RuntimeError)
+    ScratchPad.recorded.should.is_a?(RuntimeError)
   end
 
   it "raises the given exception" do
     @thr.raise Exception
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(Exception)
+    ScratchPad.recorded.should.is_a?(Exception)
   end
 
   it "raises the given exception with the given message" do
     @thr.raise Exception, "get to work"
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(Exception)
+    ScratchPad.recorded.should.is_a?(Exception)
     ScratchPad.recorded.message.should == "get to work"
   end
 
   it "raises the given exception and the backtrace is the one of the interrupted thread" do
     @thr.raise Exception
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(Exception)
-    ScratchPad.recorded.backtrace[0].should include("sleep")
+    ScratchPad.recorded.should.is_a?(Exception)
+    ScratchPad.recorded.backtrace[0].should.include?("sleep")
   end
 
   it "is captured and raised by Thread#value" do
@@ -58,7 +68,7 @@ describe "Thread#raise on a sleeping thread" do
     ThreadSpecs.spin_until_sleeping(t)
 
     t.raise
-    -> { t.value }.should raise_error(RuntimeError)
+    -> { t.value }.should.raise(RuntimeError)
   end
 
   it "raises a RuntimeError when called with no arguments inside rescue" do
@@ -76,7 +86,7 @@ describe "Thread#raise on a sleeping thread" do
       ThreadSpecs.spin_until_sleeping(t)
       t.raise
     end
-    -> { t.value }.should raise_error(RuntimeError)
+    -> { t.value }.should.raise(RuntimeError)
   end
 
   it "re-raises a previously rescued exception without overwriting the backtrace" do
@@ -98,10 +108,59 @@ describe "Thread#raise on a sleeping thread" do
       raise_again_line = __LINE__; t.raise raised
       raised_again = t.value
 
-      raised_again.backtrace.first.should include("#{__FILE__}:#{initial_raise_line}:")
-      raised_again.backtrace.first.should_not include("#{__FILE__}:#{raise_again_line}:")
+      raised_again.backtrace.first.should.include?("#{__FILE__}:#{initial_raise_line}:")
+      raised_again.backtrace.first.should_not.include?("#{__FILE__}:#{raise_again_line}:")
     end
   end
+
+  it "calls #exception in both the caller and in the target thread" do
+    cls = Class.new(Exception) do
+      attr_accessor :log
+      def initialize(*args)
+        @log = [] # This is shared because the super #exception uses a shallow clone
+        super
+      end
+
+      def exception(*args)
+        @log << [self, Thread.current, args]
+        super
+      end
+    end
+    exc = cls.new
+
+    @thr.raise exc, "Thread#raise #exception spec"
+    @thr.join
+    ScratchPad.recorded.should.is_a?(cls)
+    exc.log.should == [
+      [exc, Thread.current, ["Thread#raise #exception spec"]],
+      [ScratchPad.recorded, @thr, []]
+    ]
+  end
+
+  it "calls #set_backtrace only in the caller thread" do
+    cls = Class.new(Exception) do
+      attr_accessor :log
+      def initialize(*args)
+        @log = [] # This is shared because the super #exception uses a shallow clone
+        super
+      end
+
+      def set_backtrace(backtrace)
+        @log << [Thread.current, backtrace]
+        super
+      end
+    end
+    exc = cls.new
+
+    backtrace = ["a.rb:1"]
+
+    @thr.raise exc, "Thread#raise #set_backtrace spec", backtrace
+    @thr.join
+    ScratchPad.recorded.should.is_a?(cls)
+    exc.log.should == [
+      [Thread.current, backtrace]
+    ]
+  end
 end
 
 describe "Thread#raise on a running thread" do
@@ -121,30 +180,33 @@ describe "Thread#raise on a running thread" do
   it "raises a RuntimeError if no exception class is given" do
     @thr.raise
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(RuntimeError)
+    ScratchPad.recorded.should.is_a?(RuntimeError)
   end
 
   it "raises the given exception" do
     @thr.raise Exception
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(Exception)
+    ScratchPad.recorded.should.is_a?(Exception)
   end
 
   it "raises the given exception with the given message" do
     @thr.raise Exception, "get to work"
     Thread.pass while @thr.status
-    ScratchPad.recorded.should be_kind_of(Exception)
+    ScratchPad.recorded.should.is_a?(Exception)
     ScratchPad.recorded.message.should == "get to work"
   end
 
   it "can go unhandled" do
+    q = Queue.new
     t = Thread.new do
       Thread.current.report_on_exception = false
+      q << true
       loop { Thread.pass }
     end
 
+    q.pop # wait for `report_on_exception = false`.
     t.raise
-    -> { t.value }.should raise_error(RuntimeError)
+    -> { t.value }.should.raise(RuntimeError)
   end
 
   it "raises the given argument even when there is an active exception" do
@@ -163,7 +225,7 @@ describe "Thread#raise on a running thread" do
     rescue
       Thread.pass until raised
       t.raise RangeError
-      -> { t.value }.should raise_error(RangeError)
+      -> { t.value }.should.raise(RangeError)
     end
   end
 
@@ -184,7 +246,7 @@ describe "Thread#raise on a running thread" do
       Thread.pass until raised
       t.raise
     end
-    -> { t.value }.should raise_error(RuntimeError)
+    -> { t.value }.should.raise(RuntimeError)
   end
 end
 
@@ -200,6 +262,6 @@ describe "Thread#raise on same thread" do
         Thread.current.raise
       end
     end
-    -> { t.value }.should raise_error(RuntimeError)
+    -> { t.value }.should.raise(RuntimeError, '')
   end
 end
diff --git a/spec/ruby/core/thread/report_on_exception_spec.rb b/spec/ruby/core/thread/report_on_exception_spec.rb
index a6042ba759..9cf5260808 100644
--- a/spec/ruby/core/thread/report_on_exception_spec.rb
+++ b/spec/ruby/core/thread/report_on_exception_spec.rb
@@ -1,16 +1,8 @@
 require_relative '../../spec_helper'
 
 describe "Thread.report_on_exception" do
-  ruby_version_is "2.4"..."2.5" do
-    it "defaults to false" do
-      ruby_exe("p Thread.report_on_exception").should == "false\n"
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "defaults to true" do
-      ruby_exe("p Thread.report_on_exception").should == "true\n"
-    end
+  it "defaults to true" do
+    ruby_exe("p Thread.report_on_exception").should == "true\n"
   end
 end
 
@@ -33,14 +25,12 @@ describe "Thread.report_on_exception=" do
 end
 
 describe "Thread#report_on_exception" do
-  ruby_version_is "2.5" do
-    it "returns true for the main Thread" do
-      Thread.current.report_on_exception.should == true
-    end
+  it "returns true for the main Thread" do
+    Thread.current.report_on_exception.should == true
+  end
 
-    it "returns true for new Threads" do
-      Thread.new { Thread.current.report_on_exception }.value.should == true
-    end
+  it "returns true for new Threads" do
+    Thread.new { Thread.current.report_on_exception }.value.should == true
   end
 
   it "returns whether the Thread will print a backtrace if it exits with an exception" do
@@ -68,7 +58,56 @@ describe "Thread#report_on_exception=" do
 
       -> {
         t.join
-      }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+      }.should.raise(RuntimeError, "Thread#report_on_exception specs")
+    end
+
+    it "prints a backtrace on $stderr in the regular backtrace order" do
+      line_raise = __LINE__ + 2
+      def foo
+        raise RuntimeError, "Thread#report_on_exception specs backtrace order"
+      end
+
+      line_call_foo = __LINE__ + 5
+      go = false
+      t = Thread.new {
+        Thread.current.report_on_exception = true
+        Thread.pass until go
+        foo
+      }
+
+      -> {
+        go = true
+        Thread.pass while t.alive?
+      }.should output("", /\A
+#{Regexp.quote(t.inspect)}\sterminated\swith\sexception\s\(report_on_exception\sis\strue\):\n
+#{Regexp.quote(__FILE__)}:#{line_raise}:in\s[`']foo':\sThread\#report_on_exception\sspecs\sbacktrace\sorder\s\(RuntimeError\)\n
+\tfrom\s#{Regexp.quote(__FILE__)}:#{line_call_foo}:in\s[`']block\s\(4\slevels\)\sin\s<top\s\(required\)>'\n
+\z/x)
+
+      -> {
+        t.join
+      }.should.raise(RuntimeError, "Thread#report_on_exception specs backtrace order")
+    end
+
+    it "prints the backtrace even if the thread was killed just after Thread#raise" do
+      t = nil
+      ready = false
+      -> {
+        t = Thread.new {
+          Thread.current.report_on_exception = true
+          ready = true
+          sleep
+        }
+
+        Thread.pass until ready and t.stop?
+        t.raise RuntimeError, "Thread#report_on_exception before kill spec"
+        t.kill
+        Thread.pass while t.alive?
+      }.should output("", /Thread.+terminated with exception.+Thread#report_on_exception before kill spec/m)
+
+      -> {
+        t.join
+      }.should.raise(RuntimeError, "Thread#report_on_exception before kill spec")
     end
   end
 
@@ -85,7 +124,7 @@ describe "Thread#report_on_exception=" do
 
       -> {
         t.join
-      }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+      }.should.raise(RuntimeError, "Thread#report_on_exception specs")
     end
   end
 
@@ -105,12 +144,12 @@ describe "Thread#report_on_exception=" do
 
         -> {
           mutex.sleep(5)
-        }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+        }.should.raise(RuntimeError, "Thread#report_on_exception specs")
       }.should output("", /Thread.+terminated with exception.+Thread#report_on_exception specs/m)
 
       -> {
         t.join
-      }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+      }.should.raise(RuntimeError, "Thread#report_on_exception specs")
     end
   end
 end
diff --git a/spec/ruby/core/thread/shared/exit.rb b/spec/ruby/core/thread/shared/exit.rb
index 40dc478947..a294c3a4d6 100644
--- a/spec/ruby/core/thread/shared/exit.rb
+++ b/spec/ruby/core/thread/shared/exit.rb
@@ -56,8 +56,8 @@ describe :thread_exit, shared: true do
     Thread.pass while @inner.status and @inner.status != "sleep"
     @outer.send(@method)
     @outer.join
-    ScratchPad.recorded.should include(:inner_ensure_clause)
-    ScratchPad.recorded.should include(:outer_ensure_clause)
+    ScratchPad.recorded.should.include?(:inner_ensure_clause)
+    ScratchPad.recorded.should.include?(:outer_ensure_clause)
   end
 
   it "does not set $!" do
@@ -66,6 +66,26 @@ describe :thread_exit, shared: true do
     ScratchPad.recorded.should == nil
   end
 
+  it "does not reset $!" do
+    ScratchPad.record []
+
+    exc = RuntimeError.new("foo")
+    thread = Thread.new do
+      begin
+        raise exc
+      ensure
+        ScratchPad << $!
+        begin
+          Thread.current.send(@method)
+        ensure
+          ScratchPad << $!
+        end
+      end
+    end
+    thread.join
+    ScratchPad.recorded.should == [exc, exc]
+  end
+
   it "cannot be rescued" do
     thread = Thread.new do
       begin
@@ -73,7 +93,7 @@ describe :thread_exit, shared: true do
       rescue Exception
         ScratchPad.record :in_rescue
       end
-     ScratchPad.record :end_of_thread_block
+      ScratchPad.record :end_of_thread_block
     end
 
     thread.join
@@ -93,6 +113,25 @@ describe :thread_exit, shared: true do
     ScratchPad.recorded.should == nil
   end
 
+  it "kills other fibers of that thread without running their ensure clauses" do
+    t = Thread.new do
+      f = Fiber.new do
+        ScratchPad.record :fiber_resumed
+        begin
+          Fiber.yield
+        ensure
+          ScratchPad.record :fiber_ensure
+        end
+      end
+      f.resume
+      sleep
+    end
+    Thread.pass until t.stop?
+    t.send(@method)
+    t.join
+    ScratchPad.recorded.should == :fiber_resumed
+  end
+
   # This spec is a mess. It fails randomly, it hangs on MRI, it needs to be removed
   quarantine! do
   it "killing dying running does nothing" do
@@ -116,7 +155,7 @@ describe :thread_exit, shared: true do
 
     it "propagates inner exception to Thread.join if there is an outer ensure clause" do
       thread = ThreadSpecs.dying_thread_with_outer_ensure(@method) { }
-      -> { thread.join }.should raise_error(RuntimeError, "In dying thread")
+      -> { thread.join }.should.raise(RuntimeError, "In dying thread")
     end
 
     it "runs all outer ensure clauses even if inner ensure clause raises exception" do
diff --git a/spec/ruby/core/thread/shared/start.rb b/spec/ruby/core/thread/shared/start.rb
index 2ba926bf00..c5d62ab098 100644
--- a/spec/ruby/core/thread/shared/start.rb
+++ b/spec/ruby/core/thread/shared/start.rb
@@ -6,22 +6,22 @@ describe :thread_start, shared: true do
   it "raises an ArgumentError if not passed a block" do
     -> {
       Thread.send(@method)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "spawns a new Thread running the block" do
     run = false
     t = Thread.send(@method) { run = true }
-    t.should be_kind_of(Thread)
+    t.should.is_a?(Thread)
     t.join
 
-    run.should be_true
+    run.should == true
   end
 
   it "respects Thread subclasses" do
     c = Class.new(Thread)
     t = c.send(@method) { }
-    t.should be_kind_of(c)
+    t.should.is_a?(c)
 
     t.join
   end
diff --git a/spec/ruby/core/thread/shared/to_s.rb b/spec/ruby/core/thread/shared/to_s.rb
new file mode 100644
index 0000000000..27e53ba4b8
--- /dev/null
+++ b/spec/ruby/core/thread/shared/to_s.rb
@@ -0,0 +1,53 @@
+require_relative '../fixtures/classes'
+
+describe :thread_to_s, shared: true do
+  it "returns a description including file and line number" do
+    thread, line = Thread.new { "hello" }, __LINE__
+    thread.join
+    thread.send(@method).should =~ /^#<Thread:([^ ]*?) #{Regexp.escape __FILE__}:#{line} \w+>$/
+  end
+
+  it "has a binary encoding" do
+    ThreadSpecs.status_of_current_thread.send(@method).encoding.should == Encoding::BINARY
+  end
+
+  it "can check it's own status" do
+    ThreadSpecs.status_of_current_thread.send(@method).should.include?('run')
+  end
+
+  it "describes a running thread" do
+    ThreadSpecs.status_of_running_thread.send(@method).should.include?('run')
+  end
+
+  it "describes a sleeping thread" do
+    ThreadSpecs.status_of_sleeping_thread.send(@method).should.include?('sleep')
+  end
+
+  it "describes a blocked thread" do
+    ThreadSpecs.status_of_blocked_thread.send(@method).should.include?('sleep')
+  end
+
+  it "describes a completed thread" do
+    ThreadSpecs.status_of_completed_thread.send(@method).should.include?('dead')
+  end
+
+  it "describes a killed thread" do
+    ThreadSpecs.status_of_killed_thread.send(@method).should.include?('dead')
+  end
+
+  it "describes a thread with an uncaught exception" do
+    ThreadSpecs.status_of_thread_with_uncaught_exception.send(@method).should.include?('dead')
+  end
+
+  it "describes a dying sleeping thread" do
+    ThreadSpecs.status_of_dying_sleeping_thread.send(@method).should.include?('sleep')
+  end
+
+  it "reports aborting on a killed thread" do
+    ThreadSpecs.status_of_dying_running_thread.send(@method).should.include?('aborting')
+  end
+
+  it "reports aborting on a killed thread after sleep" do
+    ThreadSpecs.status_of_dying_thread_after_sleep.send(@method).should.include?('aborting')
+  end
+end
diff --git a/spec/ruby/core/thread/shared/wakeup.rb b/spec/ruby/core/thread/shared/wakeup.rb
index f111edf0fd..c89235ba60 100644
--- a/spec/ruby/core/thread/shared/wakeup.rb
+++ b/spec/ruby/core/thread/shared/wakeup.rb
@@ -36,7 +36,7 @@ describe :thread_wakeup, shared: true do
 
   it "does not result in a deadlock" do
     t = Thread.new do
-      100.times { Thread.stop }
+      10.times { Thread.stop }
     end
 
     while t.status
@@ -47,6 +47,7 @@ describe :thread_wakeup, shared: true do
         t.status.should == false
       end
       Thread.pass
+      sleep 0.001
     end
 
     t.status.should == false
@@ -56,6 +57,6 @@ describe :thread_wakeup, shared: true do
   it "raises a ThreadError when trying to wake up a dead thread" do
     t = Thread.new { 1 }
     t.join
-    -> { t.send @method }.should raise_error(ThreadError)
+    -> { t.send @method }.should.raise(ThreadError)
   end
 end
diff --git a/spec/ruby/core/thread/stop_spec.rb b/spec/ruby/core/thread/stop_spec.rb
index 33cf8f7b5c..084ab46ef6 100644
--- a/spec/ruby/core/thread/stop_spec.rb
+++ b/spec/ruby/core/thread/stop_spec.rb
@@ -13,42 +13,42 @@ end
 
 describe "Thread#stop?" do
   it "can check it's own status" do
-    ThreadSpecs.status_of_current_thread.stop?.should == false
+    ThreadSpecs.status_of_current_thread.should_not.stop?
   end
 
   it "describes a running thread" do
-    ThreadSpecs.status_of_running_thread.stop?.should == false
+    ThreadSpecs.status_of_running_thread.should_not.stop?
   end
 
   it "describes a sleeping thread" do
-    ThreadSpecs.status_of_sleeping_thread.stop?.should == true
+    ThreadSpecs.status_of_sleeping_thread.should.stop?
   end
 
   it "describes a blocked thread" do
-    ThreadSpecs.status_of_blocked_thread.stop?.should == true
+    ThreadSpecs.status_of_blocked_thread.should.stop?
   end
 
   it "describes a completed thread" do
-    ThreadSpecs.status_of_completed_thread.stop?.should == true
+    ThreadSpecs.status_of_completed_thread.should.stop?
   end
 
   it "describes a killed thread" do
-    ThreadSpecs.status_of_killed_thread.stop?.should == true
+    ThreadSpecs.status_of_killed_thread.should.stop?
   end
 
   it "describes a thread with an uncaught exception" do
-    ThreadSpecs.status_of_thread_with_uncaught_exception.stop?.should == true
+    ThreadSpecs.status_of_thread_with_uncaught_exception.should.stop?
   end
 
   it "describes a dying running thread" do
-    ThreadSpecs.status_of_dying_running_thread.stop?.should == false
+    ThreadSpecs.status_of_dying_running_thread.should_not.stop?
   end
 
   it "describes a dying sleeping thread" do
-    ThreadSpecs.status_of_dying_sleeping_thread.stop?.should == true
+    ThreadSpecs.status_of_dying_sleeping_thread.should.stop?
   end
 
   it "describes a dying thread after sleep" do
-    ThreadSpecs.status_of_dying_thread_after_sleep.stop?.should == false
+    ThreadSpecs.status_of_dying_thread_after_sleep.should_not.stop?
   end
 end
diff --git a/spec/ruby/core/thread/thread_variable_get_spec.rb b/spec/ruby/core/thread/thread_variable_get_spec.rb
index 38f90d5830..3d92cd5479 100644
--- a/spec/ruby/core/thread/thread_variable_get_spec.rb
+++ b/spec/ruby/core/thread/thread_variable_get_spec.rb
@@ -10,16 +10,51 @@ describe "Thread#thread_variable_get" do
   end
 
   it "returns nil if the variable is not set" do
-    @t.thread_variable_get(:a).should be_nil
+    @t.thread_variable_get(:a).should == nil
   end
 
-  it "returns the value previously set by #[]=" do
-    @t.thread_variable_set :a, 49
+  it "returns the value previously set by #thread_variable_set" do
+    @t.thread_variable_set(:a, 49)
     @t.thread_variable_get(:a).should == 49
   end
 
   it "returns a value private to self" do
-    @t.thread_variable_set :thread_variable_get_spec, 82
-    Thread.current.thread_variable_get(:thread_variable_get_spec).should be_nil
+    @t.thread_variable_set(:thread_variable_get_spec, 82)
+    Thread.current.thread_variable_get(:thread_variable_get_spec).should == nil
+  end
+
+  it "accepts String and Symbol keys interchangeably" do
+    @t.thread_variable_set("a", 49)
+    @t.thread_variable_get("a").should == 49
+    @t.thread_variable_get(:a).should == 49
+  end
+
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('key')
+    key.should_receive(:to_str).and_return('a')
+    @t.thread_variable_set(:a, 49)
+    @t.thread_variable_get(key).should == 49
+  end
+
+  it "does not raise FrozenError if the thread is frozen" do
+    @t.freeze
+    @t.thread_variable_get(:a).should == nil
+  end
+
+  it "raises a TypeError if the key is neither Symbol nor String when thread variables are already set" do
+    @t.thread_variable_set(:a, 49)
+    -> { @t.thread_variable_get(123) }.should.raise(TypeError, /123 is not a symbol/)
+  end
+
+  ruby_version_is '3.4' do
+    it "raises a TypeError if the key is neither Symbol nor String when no thread variables are set" do
+      -> { @t.thread_variable_get(123) }.should.raise(TypeError, /123 is not a symbol/)
+    end
+
+    it "raises a TypeError if the key is neither Symbol nor String without calling #to_sym" do
+      key = mock('key')
+      key.should_not_receive(:to_sym)
+      -> { @t.thread_variable_get(key) }.should.raise(TypeError, /#{Regexp.escape(key.inspect)} is not a symbol/)
+    end
   end
 end
diff --git a/spec/ruby/core/thread/thread_variable_set_spec.rb b/spec/ruby/core/thread/thread_variable_set_spec.rb
index 1338c306c7..f8d25364ae 100644
--- a/spec/ruby/core/thread/thread_variable_set_spec.rb
+++ b/spec/ruby/core/thread/thread_variable_set_spec.rb
@@ -10,17 +10,53 @@ describe "Thread#thread_variable_set" do
   end
 
   it "returns the value set" do
-    (@t.thread_variable_set :a, 2).should == 2
+    @t.thread_variable_set(:a, 2).should == 2
   end
 
   it "sets a value that will be returned by #thread_variable_get" do
-    @t.thread_variable_set :a, 49
+    @t.thread_variable_set(:a, 49)
     @t.thread_variable_get(:a).should == 49
   end
 
   it "sets a value private to self" do
-    @t.thread_variable_set :thread_variable_get_spec, 82
+    @t.thread_variable_set(:thread_variable_get_spec, 82)
     @t.thread_variable_get(:thread_variable_get_spec).should == 82
-    Thread.current.thread_variable_get(:thread_variable_get_spec).should be_nil
+    Thread.current.thread_variable_get(:thread_variable_get_spec).should == nil
+  end
+
+  it "accepts String and Symbol keys interchangeably" do
+    @t.thread_variable_set('a', 49)
+    @t.thread_variable_get('a').should == 49
+
+    @t.thread_variable_set(:a, 50)
+    @t.thread_variable_get('a').should == 50
+  end
+
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('key')
+    key.should_receive(:to_str).and_return('a')
+    @t.thread_variable_set(key, 49)
+    @t.thread_variable_get(:a).should == 49
+  end
+
+  it "removes a key if the value is nil" do
+    @t.thread_variable_set(:a, 52)
+    @t.thread_variable_set(:a, nil)
+    @t.thread_variable?(:a).should == false
+  end
+
+  it "raises a FrozenError if the thread is frozen" do
+    @t.freeze
+    -> { @t.thread_variable_set(:a, 1) }.should.raise(FrozenError, "can't modify frozen thread locals")
+  end
+
+  it "raises a TypeError if the key is neither Symbol nor String, nor responds to #to_str" do
+    -> { @t.thread_variable_set(123, 1) }.should.raise(TypeError, /123 is not a symbol/)
+  end
+
+  it "does not try to convert the key with #to_sym" do
+    key = mock('key')
+    key.should_not_receive(:to_sym)
+    -> { @t.thread_variable_set(key, 42) }.should.raise(TypeError, /#{Regexp.quote(key.inspect)} is not a symbol/)
   end
 end
diff --git a/spec/ruby/core/thread/thread_variable_spec.rb b/spec/ruby/core/thread/thread_variable_spec.rb
index 6bd1950c04..ebafd4f3eb 100644
--- a/spec/ruby/core/thread/thread_variable_spec.rb
+++ b/spec/ruby/core/thread/thread_variable_spec.rb
@@ -10,12 +10,51 @@ describe "Thread#thread_variable?" do
   end
 
   it "returns false if the thread variables do not contain 'key'" do
-    @t.thread_variable_set :a, 2
-    @t.thread_variable?(:b).should be_false
+    @t.thread_variable_set(:a, 2)
+    @t.thread_variable?(:b).should == false
   end
 
   it "returns true if the thread variables contain 'key'" do
-    @t.thread_variable_set :a, 2
-    @t.thread_variable?(:a).should be_true
+    @t.thread_variable_set(:a, 2)
+    @t.thread_variable?(:a).should == true
+  end
+
+  it "accepts String and Symbol keys interchangeably" do
+    @t.thread_variable?('a').should == false
+    @t.thread_variable?(:a).should == false
+
+    @t.thread_variable_set(:a, 49)
+
+    @t.thread_variable?('a').should == true
+    @t.thread_variable?(:a).should == true
+  end
+
+  it "converts a key that is neither String nor Symbol with #to_str" do
+    key = mock('key')
+    key.should_receive(:to_str).and_return('a')
+    @t.thread_variable_set(:a, 49)
+    @t.thread_variable?(key).should == true
+  end
+
+  it "does not raise FrozenError if the thread is frozen" do
+    @t.freeze
+    @t.thread_variable?(:a).should == false
+  end
+
+  it "raises a TypeError if the key is neither Symbol nor String when thread variables are already set" do
+    @t.thread_variable_set(:a, 49)
+    -> { @t.thread_variable?(123) }.should.raise(TypeError, /123 is not a symbol/)
+  end
+
+  ruby_version_is '3.4' do
+    it "raises a TypeError if the key is neither Symbol nor String when no thread variables are set" do
+      -> { @t.thread_variable?(123) }.should.raise(TypeError, /123 is not a symbol/)
+    end
+
+    it "raises a TypeError if the key is neither Symbol nor String without calling #to_sym" do
+      key = mock('key')
+      key.should_not_receive(:to_sym)
+      -> { @t.thread_variable?(key) }.should.raise(TypeError, /#{Regexp.escape(key.inspect)} is not a symbol/)
+    end
   end
 end
diff --git a/spec/ruby/core/thread/thread_variables_spec.rb b/spec/ruby/core/thread/thread_variables_spec.rb
index 1bd68b17f1..f15c681a8f 100644
--- a/spec/ruby/core/thread/thread_variables_spec.rb
+++ b/spec/ruby/core/thread/thread_variables_spec.rb
@@ -10,20 +10,31 @@ describe "Thread#thread_variables" do
   end
 
   it "returns the keys of all the values set" do
-    @t.thread_variable_set :a, 2
-    @t.thread_variable_set :b, 4
-    @t.thread_variable_set :c, 6
+    @t.thread_variable_set(:a, 2)
+    @t.thread_variable_set(:b, 4)
+    @t.thread_variable_set(:c, 6)
     @t.thread_variables.sort.should == [:a, :b, :c]
   end
 
-  it "sets a value private to self" do
-    @t.thread_variable_set :a, 82
-    @t.thread_variable_set :b, 82
-    Thread.current.thread_variables.should_not include(:a, :b)
+  it "returns the keys private to self" do
+    @t.thread_variable_set(:a, 82)
+    @t.thread_variable_set(:b, 82)
+    Thread.current.thread_variables.should_not.include?(:a)
+    Thread.current.thread_variables.should_not.include?(:b)
   end
 
   it "only contains user thread variables and is empty initially" do
     Thread.current.thread_variables.should == []
     @t.thread_variables.should == []
   end
+
+  it "returns keys as Symbols" do
+    key = mock('key')
+    key.should_receive(:to_str).and_return('a')
+
+    @t.thread_variable_set(key, 49)
+    @t.thread_variable_set('b', 50)
+    @t.thread_variable_set(:c, 51)
+    @t.thread_variables.sort.should == [:a, :b, :c]
+  end
 end
diff --git a/spec/ruby/core/thread/to_s_spec.rb b/spec/ruby/core/thread/to_s_spec.rb
new file mode 100644
index 0000000000..cb182a017f
--- /dev/null
+++ b/spec/ruby/core/thread/to_s_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/to_s'
+
+describe "Thread#to_s" do
+  it_behaves_like :thread_to_s, :to_s
+end
diff --git a/spec/ruby/core/thread/value_spec.rb b/spec/ruby/core/thread/value_spec.rb
index 30e43abd1a..50c823171d 100644
--- a/spec/ruby/core/thread/value_spec.rb
+++ b/spec/ruby/core/thread/value_spec.rb
@@ -11,7 +11,7 @@ describe "Thread#value" do
       Thread.current.report_on_exception = false
       raise "Hello"
     }
-    -> { t.value }.should raise_error(RuntimeError, "Hello")
+    -> { t.value }.should.raise(RuntimeError, "Hello")
   end
 
   it "is nil for a killed thread" do
diff --git a/spec/ruby/core/threadgroup/default_spec.rb b/spec/ruby/core/threadgroup/default_spec.rb
index d7d4726cc2..4f57508abf 100644
--- a/spec/ruby/core/threadgroup/default_spec.rb
+++ b/spec/ruby/core/threadgroup/default_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "ThreadGroup::Default" do
   it "is a ThreadGroup instance" do
-    ThreadGroup::Default.should be_kind_of(ThreadGroup)
+    ThreadGroup::Default.should.is_a?(ThreadGroup)
   end
 
   it "is the ThreadGroup of the main thread" do
diff --git a/spec/ruby/core/threadgroup/enclose_spec.rb b/spec/ruby/core/threadgroup/enclose_spec.rb
index dd9a7a362d..6f703d4ce2 100644
--- a/spec/ruby/core/threadgroup/enclose_spec.rb
+++ b/spec/ruby/core/threadgroup/enclose_spec.rb
@@ -19,6 +19,6 @@ describe "ThreadGroup#enclose" do
     thread_group.enclose
     -> do
       default_group.add(@thread)
-    end.should raise_error(ThreadError)
+    end.should.raise(ThreadError)
   end
 end
diff --git a/spec/ruby/core/threadgroup/enclosed_spec.rb b/spec/ruby/core/threadgroup/enclosed_spec.rb
index a734256a64..cf8a5bb4c6 100644
--- a/spec/ruby/core/threadgroup/enclosed_spec.rb
+++ b/spec/ruby/core/threadgroup/enclosed_spec.rb
@@ -3,12 +3,12 @@ require_relative '../../spec_helper'
 describe "ThreadGroup#enclosed?" do
   it "returns false when a ThreadGroup has not been enclosed (default state)" do
     thread_group = ThreadGroup.new
-    thread_group.enclosed?.should be_false
+    thread_group.enclosed?.should == false
   end
 
   it "returns true when a ThreadGroup is enclosed" do
     thread_group = ThreadGroup.new
     thread_group.enclose
-    thread_group.enclosed?.should be_true
+    thread_group.enclosed?.should == true
   end
 end
diff --git a/spec/ruby/core/threadgroup/list_spec.rb b/spec/ruby/core/threadgroup/list_spec.rb
index b2ac64324a..ef601d75ea 100644
--- a/spec/ruby/core/threadgroup/list_spec.rb
+++ b/spec/ruby/core/threadgroup/list_spec.rb
@@ -7,13 +7,13 @@ describe "ThreadGroup#list" do
     q.pop.should == :go
     tg = ThreadGroup.new
     tg.add(th1)
-    tg.list.should include(th1)
+    tg.list.should.include?(th1)
 
     th2 = Thread.new { q << :go; sleep }
     q.pop.should == :go
 
     tg.add(th2)
-    (tg.list & [th1, th2]).should include(th1, th2)
+    (tg.list & [th1, th2]).to_set.should == Set[th1, th2]
 
     Thread.pass while th1.status and th1.status != 'sleep'
     Thread.pass while th2.status and th2.status != 'sleep'
diff --git a/spec/ruby/core/time/_dump_spec.rb b/spec/ruby/core/time/_dump_spec.rb
index 6941a1531f..21f0806327 100644
--- a/spec/ruby/core/time/_dump_spec.rb
+++ b/spec/ruby/core/time/_dump_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 
 describe "Time#_dump" do
@@ -10,22 +10,22 @@ describe "Time#_dump" do
   end
 
   it "is a private method" do
-    Time.should have_private_instance_method(:_dump, false)
+    Time.private_instance_methods(false).should.include?(:_dump)
   end
 
   # http://redmine.ruby-lang.org/issues/show/627
   it "preserves the GMT flag" do
-    @t.gmt?.should == true
+    @t.should.gmt?
     dump = @t.send(:_dump).unpack("VV").first
     ((dump >> 30) & 0x1).should == 1
 
-    @local.gmt?.should == false
+    @local.should_not.gmt?
     dump = @local.send(:_dump).unpack("VV").first
     ((dump >> 30) & 0x1).should == 0
   end
 
   it "dumps a Time object to a bytestring" do
-    @s.should be_an_instance_of(String)
+    @s.should.instance_of?(String)
     @s.should == [3222863947, 2235564032].pack("VV")
   end
 
diff --git a/spec/ruby/core/time/_load_spec.rb b/spec/ruby/core/time/_load_spec.rb
index 152934370f..a74e3dc129 100644
--- a/spec/ruby/core/time/_load_spec.rb
+++ b/spec/ruby/core/time/_load_spec.rb
@@ -1,9 +1,9 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 
 describe "Time._load" do
   it "is a private method" do
-    Time.should have_private_method(:_load, false)
+    Time.private_methods(false).should.include?(:_load)
   end
 
   # http://redmine.ruby-lang.org/issues/show/627
@@ -44,8 +44,7 @@ describe "Time._load" do
   end
 
   it "treats the data as binary data" do
-    data = "\x04\bu:\tTime\r\fM\x1C\xC0\x00\x00\xD0\xBE"
-    data.force_encoding Encoding::UTF_8
+    data = "\x04\bu:\tTime\r\fM\x1C\xC0\x00\x00\xD0\xBE".dup.force_encoding Encoding::UTF_8
     t = Marshal.load(data)
     t.to_s.should == "2013-04-08 12:47:45 UTC"
   end
diff --git a/spec/ruby/core/time/at_spec.rb b/spec/ruby/core/time/at_spec.rb
index 8434e8dd16..10d4d36a68 100644
--- a/spec/ruby/core/time/at_spec.rb
+++ b/spec/ruby/core/time/at_spec.rb
@@ -14,13 +14,13 @@ describe "Time.at" do
     end
 
     it "returns a non-UTC Time" do
-      Time.at(1184027924).utc?.should == false
+      Time.at(1184027924).should_not.utc?
     end
 
     it "returns a subclass instance on a Time subclass" do
       c = Class.new(Time)
       t = c.at(0)
-      t.should be_an_instance_of(c)
+      t.should.instance_of?(c)
     end
 
     it "roundtrips a Rational produced by #to_r" do
@@ -32,10 +32,17 @@ describe "Time.at" do
       t2.nsec.should == t.nsec
     end
 
-    describe "passed BigDecimal" do
-      it "doesn't round input value" do
-        require 'bigdecimal'
-        Time.at(BigDecimal('1.1')).to_f.should == 1.1
+    describe "passed Rational" do
+      it "returns Time with correct microseconds" do
+        t = Time.at(Rational(1_486_570_508_539_759, 1_000_000))
+        t.usec.should == 539_759
+        t.nsec.should == 539_759_000
+      end
+
+      it "returns Time with correct nanoseconds" do
+        t = Time.at(Rational(1_486_570_508_539_759_123, 1_000_000_000))
+        t.usec.should == 539_759
+        t.nsec.should == 539_759_123
       end
     end
   end
@@ -49,33 +56,33 @@ describe "Time.at" do
     it "creates a dup time object with the value given by time" do
       t1 = Time.new
       t2 = Time.at(t1)
-      t1.should_not equal t2
+      t1.should_not.equal? t2
     end
 
     it "returns a UTC time if the argument is UTC" do
       t = Time.now.getgm
-      Time.at(t).utc?.should == true
+      Time.at(t).should.utc?
     end
 
     it "returns a non-UTC time if the argument is non-UTC" do
       t = Time.now
-      Time.at(t).utc?.should == false
+      Time.at(t).should_not.utc?
     end
 
     it "returns a subclass instance" do
       c = Class.new(Time)
       t = c.at(Time.now)
-      t.should be_an_instance_of(c)
+      t.should.instance_of?(c)
     end
   end
 
   describe "passed non-Time, non-Numeric" do
     it "raises a TypeError with a String argument" do
-      -> { Time.at("0") }.should raise_error(TypeError)
+      -> { Time.at("0") }.should.raise(TypeError)
     end
 
     it "raises a TypeError with a nil argument" do
-      -> { Time.at(nil) }.should raise_error(TypeError)
+      -> { Time.at(nil) }.should.raise(TypeError)
     end
 
     describe "with an argument that responds to #to_int" do
@@ -92,6 +99,12 @@ describe "Time.at" do
         o.should_receive(:to_r).and_return(Rational(5, 2))
         Time.at(o).should == Time.at(Rational(5, 2))
       end
+
+      it "needs for the argument to respond to #to_int too" do
+        o = mock('rational-but-no-to_int')
+        def o.to_r; Rational(5, 2) end
+        -> { Time.at(o) }.should.raise(TypeError, "can't convert MockObject into an exact number")
+      end
     end
   end
 
@@ -127,127 +140,176 @@ describe "Time.at" do
 
   describe "passed [Integer, nil]" do
     it "raises a TypeError" do
-      -> { Time.at(0, nil) }.should raise_error(TypeError)
+      -> { Time.at(0, nil) }.should.raise(TypeError)
     end
   end
 
   describe "passed [Integer, String]" do
     it "raises a TypeError" do
-      -> { Time.at(0, "0") }.should raise_error(TypeError)
+      -> { Time.at(0, "0") }.should.raise(TypeError)
     end
   end
 
   describe "passed [Time, Integer]" do
     # #8173
     it "raises a TypeError" do
-      -> { Time.at(Time.now, 500000) }.should raise_error(TypeError)
+      -> { Time.at(Time.now, 500000) }.should.raise(TypeError)
     end
   end
 
-  ruby_version_is "2.5" do
-    describe "passed [Time, Numeric, format]" do
-      context ":nanosecond format" do
-        it "traits second argument as nanoseconds" do
-          Time.at(0, 123456789, :nanosecond).nsec.should == 123456789
-        end
+  describe "passed [Time, Numeric, format]" do
+    context ":nanosecond format" do
+      it "treats second argument as nanoseconds" do
+        Time.at(0, 123456789, :nanosecond).nsec.should == 123456789
       end
+    end
 
-      context ":nsec format" do
-        it "traits second argument as nanoseconds" do
-          Time.at(0, 123456789, :nsec).nsec.should == 123456789
-        end
+    context ":nsec format" do
+      it "treats second argument as nanoseconds" do
+        Time.at(0, 123456789, :nsec).nsec.should == 123456789
       end
+    end
 
-      context ":microsecond format" do
-        it "traits second argument as microseconds" do
-          Time.at(0, 123456, :microsecond).nsec.should == 123456000
-        end
+    context ":microsecond format" do
+      it "treats second argument as microseconds" do
+        Time.at(0, 123456, :microsecond).nsec.should == 123456000
       end
+    end
 
-      context ":usec format" do
-        it "traits second argument as microseconds" do
-          Time.at(0, 123456, :usec).nsec.should == 123456000
-        end
+    context ":usec format" do
+      it "treats second argument as microseconds" do
+        Time.at(0, 123456, :usec).nsec.should == 123456000
       end
+    end
 
-      context ":millisecond format" do
-        it "traits second argument as milliseconds" do
-          Time.at(0, 123, :millisecond).nsec.should == 123000000
-        end
+    context ":millisecond format" do
+      it "treats second argument as milliseconds" do
+        Time.at(0, 123, :millisecond).nsec.should == 123000000
       end
+    end
 
-      context "not supported format" do
-        it "raises ArgumentError" do
-          -> { Time.at(0, 123456, 2) }.should raise_error(ArgumentError)
-          -> { Time.at(0, 123456, nil) }.should raise_error(ArgumentError)
-          -> { Time.at(0, 123456, :invalid) }.should raise_error(ArgumentError)
-        end
-
-        it "does not try to convert format to Symbol with #to_sym" do
-          format = "usec"
-          format.should_not_receive(:to_sym)
-          -> { Time.at(0, 123456, format) }.should raise_error(ArgumentError)
-        end
+    context "not supported format" do
+      it "raises ArgumentError" do
+        -> { Time.at(0, 123456, 2) }.should.raise(ArgumentError)
+        -> { Time.at(0, 123456, nil) }.should.raise(ArgumentError)
+        -> { Time.at(0, 123456, :invalid) }.should.raise(ArgumentError)
       end
 
-      it "supports Float second argument" do
-        Time.at(0, 123456789.500, :nanosecond).nsec.should == 123456789
-        Time.at(0, 123456789.500, :nsec).nsec.should == 123456789
-        Time.at(0, 123456.500, :microsecond).nsec.should == 123456500
-        Time.at(0, 123456.500, :usec).nsec.should == 123456500
-        Time.at(0, 123.500, :millisecond).nsec.should == 123500000
+      it "does not try to convert format to Symbol with #to_sym" do
+        format = +"usec"
+        format.should_not_receive(:to_sym)
+        -> { Time.at(0, 123456, format) }.should.raise(ArgumentError)
       end
     end
+
+    it "supports Float second argument" do
+      Time.at(0, 123456789.500, :nanosecond).nsec.should == 123456789
+      Time.at(0, 123456789.500, :nsec).nsec.should == 123456789
+      Time.at(0, 123456.500, :microsecond).nsec.should == 123456500
+      Time.at(0, 123456.500, :usec).nsec.should == 123456500
+      Time.at(0, 123.500, :millisecond).nsec.should == 123500000
+    end
   end
 
-  ruby_version_is "2.6" do
-    describe ":in keyword argument" do
-      before do
-        @epoch_time = Time.now.to_i
-      end
+  describe ":in keyword argument" do
+    before do
+      @epoch_time = Time.now.to_i
+    end
 
-      it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
-        time = Time.at(@epoch_time, in: "+05:00")
+    it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
+      time = Time.at(@epoch_time, in: "+05:00")
 
-        time.utc_offset.should == 5*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
 
-        time = Time.at(@epoch_time, in: "-09:00")
+      time = Time.at(@epoch_time, in: "-09:00")
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
-      end
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
 
-      it "could be UTC offset as a number of seconds" do
-        time = Time.at(@epoch_time, in: 5*60*60)
+      time = Time.at(@epoch_time, in: "-09:00:01")
 
-        time.utc_offset.should == 5*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == -(9*60*60 + 1)
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+    end
 
-        time = Time.at(@epoch_time, in: -9*60*60)
+    it "could be UTC offset as a number of seconds" do
+      time = Time.at(@epoch_time, in: 5*60*60)
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
-      end
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+
+      time = Time.at(@epoch_time, in: -9*60*60)
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+    end
+
+    it "could be UTC offset as a 'UTC' String" do
+      time = Time.at(@epoch_time, in: "UTC")
+
+      time.utc_offset.should == 0
+      time.zone.should == "UTC"
+      time.to_i.should == @epoch_time
+    end
+
+    it "could be UTC offset as a military zone A-Z" do
+      time = Time.at(@epoch_time, in: "B")
+
+      time.utc_offset.should == 3600 * 2
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+    end
+
+    it "could be a timezone object" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.at(@epoch_time, in: zone)
+
+      time.utc_offset.should == 5*3600+30*60
+      time.zone.should == zone
+      time.to_i.should == @epoch_time
 
-      it "could be a timezone object" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = Time.at(@epoch_time, in: zone)
+      zone = TimeSpecs::TimezoneWithName.new(name: "PST")
+      time = Time.at(@epoch_time, in: zone)
 
-        time.utc_offset.should == 5*3600+30*60
-        time.zone.should == zone
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == -9*60*60
+      time.zone.should == zone
+      time.to_i.should == @epoch_time
+    end
+
+    it "raises ArgumentError if format is invalid" do
+      -> { Time.at(@epoch_time, in: "+09:99") }.should.raise(ArgumentError)
+      -> { Time.at(@epoch_time, in: "ABC") }.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError if hours greater than 23" do # TODO
+      -> { Time.at(@epoch_time, in: "+24:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.at(@epoch_time, in: "+2400") }.should.raise(ArgumentError, "utc_offset out of range")
+
+      -> { Time.at(@epoch_time, in: "+99:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.at(@epoch_time, in: "+9900") }.should.raise(ArgumentError, "utc_offset out of range")
+    end
+
+    it "raises ArgumentError if minutes greater than 59" do # TODO
+      -> { Time.at(@epoch_time, in: "+00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+      -> { Time.at(@epoch_time, in: "+0060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+      -> { Time.at(@epoch_time, in: "+00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+      -> { Time.at(@epoch_time, in: "+0099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+    end
 
-        zone = TimeSpecs::TimezoneWithName.new(name: "PST")
-        time = Time.at(@epoch_time, in: zone)
+    ruby_bug '#20797', ''...'3.4' do
+      it "raises ArgumentError if seconds greater than 59" do
+        -> { Time.at(@epoch_time, in: "+00:00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+        -> { Time.at(@epoch_time, in: "+000060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == zone
-        time.to_i.should == @epoch_time
+        -> { Time.at(@epoch_time, in: "+00:00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+        -> { Time.at(@epoch_time, in: "+000099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
       end
     end
   end
diff --git a/spec/ruby/core/time/ceil_spec.rb b/spec/ruby/core/time/ceil_spec.rb
index 29dcec5d72..18e26f9994 100644
--- a/spec/ruby/core/time/ceil_spec.rb
+++ b/spec/ruby/core/time/ceil_spec.rb
@@ -1,45 +1,44 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.7" do
-  describe "Time#ceil" do
-    before do
-      @time = Time.utc(2010, 3, 30, 5, 43, "25.0123456789".to_r)
-    end
+describe "Time#ceil" do
+  before do
+    @time = Time.utc(2010, 3, 30, 5, 43, "25.0123456789".to_r)
+  end
 
-    it "defaults to ceiling to 0 places" do
-      @time.ceil.should == Time.utc(2010, 3, 30, 5, 43, 26.to_r)
-    end
+  it "defaults to ceiling to 0 places" do
+    @time.ceil.should == Time.utc(2010, 3, 30, 5, 43, 26.to_r)
+  end
 
-    it "ceils to 0 decimal places with an explicit argument" do
-      @time.ceil(0).should == Time.utc(2010, 3, 30, 5, 43, 26.to_r)
-    end
+  it "ceils to 0 decimal places with an explicit argument" do
+    @time.ceil(0).should == Time.utc(2010, 3, 30, 5, 43, 26.to_r)
+  end
 
-    it "ceils to 2 decimal places with an explicit argument" do
-      @time.ceil(2).should == Time.utc(2010, 3, 30, 5, 43, "25.02".to_r)
-    end
+  it "ceils to 2 decimal places with an explicit argument" do
+    @time.ceil(2).should == Time.utc(2010, 3, 30, 5, 43, "25.02".to_r)
+  end
 
-    it "ceils to 4 decimal places with an explicit argument" do
-      @time.ceil(4).should == Time.utc(2010, 3, 30, 5, 43, "25.0124".to_r)
-    end
+  it "ceils to 4 decimal places with an explicit argument" do
+    @time.ceil(4).should == Time.utc(2010, 3, 30, 5, 43, "25.0124".to_r)
+  end
 
-    it "ceils to 7 decimal places with an explicit argument" do
-      @time.ceil(7).should == Time.utc(2010, 3, 30, 5, 43, "25.0123457".to_r)
-    end
+  it "ceils to 7 decimal places with an explicit argument" do
+    @time.ceil(7).should == Time.utc(2010, 3, 30, 5, 43, "25.0123457".to_r)
+  end
 
-    it "returns an instance of Time, even if #ceil is called on a subclass" do
-      subclass = Class.new(Time)
-      instance = subclass.at(0)
-      instance.class.should equal subclass
-      instance.ceil.should be_an_instance_of(Time)
-    end
+  it "returns an instance of Time, even if #ceil is called on a subclass" do
+    subclass = Class.new(Time)
+    instance = subclass.at(0)
+    instance.class.should.equal? subclass
+    instance.ceil.should.instance_of?(Time)
+  end
 
-    it "copies own timezone to the returning value" do
-      @time.zone.should == @time.ceil.zone
+  it "copies own timezone to the returning value" do
+    @time.zone.should == @time.ceil.zone
 
-      with_timezone "JST-9" do
-        time = Time.at 0, 1
-        time.zone.should == time.ceil.zone
-      end
+    time = with_timezone "JST-9" do
+      Time.at 0, 1
     end
+
+    time.zone.should == time.ceil.zone
   end
 end
diff --git a/spec/ruby/core/time/comparison_spec.rb b/spec/ruby/core/time/comparison_spec.rb
index 5b53c9fb50..0790088f9e 100644
--- a/spec/ruby/core/time/comparison_spec.rb
+++ b/spec/ruby/core/time/comparison_spec.rb
@@ -55,6 +55,32 @@ describe "Time#<=>" do
     }.should_not complain
   end
 
+  context "given different timezones" do
+    it "returns 0 if time is the same as other" do
+      # three timezones, all at the same timestamp
+      time_utc = Time.new(2000, 1, 1, 0, 0, 0, 0)
+      time_cet = Time.new(2000, 1, 1, 1, 0, 0, '+01:00')
+      time_brt = Time.new(1999, 12, 31, 21, 0, 0, '-03:00')
+      (time_utc <=> time_cet).should == 0
+      (time_utc <=> time_brt).should == 0
+      (time_cet <=> time_brt).should == 0
+    end
+
+    it "returns -1 if the first argument is before the second argument" do
+      # time_brt is later, even though the date is earlier
+      time_utc = Time.new(2000, 1, 1, 0, 0, 0, 0)
+      time_brt = Time.new(1999, 12, 31, 23, 0, 0, '-03:00')
+      (time_utc <=> time_brt).should == -1
+    end
+
+    it "returns 1 if the first argument is before the second argument" do
+      # time_brt is later, even though the date is earlier
+      time_utc = Time.new(2000, 1, 1, 0, 0, 0, 0)
+      time_brt = Time.new(1999, 12, 31, 23, 0, 0, '-03:00')
+      (time_brt <=> time_utc).should == 1
+    end
+  end
+
   describe "given a non-Time argument" do
     it "returns nil if argument <=> self returns nil" do
       t = Time.now
@@ -98,7 +124,7 @@ describe "Time#<=>" do
       def r.<=>(other); other <=> self; end
       r.should_receive(:<=>).once
 
-      (t <=> r).should be_nil
+      (t <=> r).should == nil
     end
   end
 end
diff --git a/spec/ruby/core/time/deconstruct_keys_spec.rb b/spec/ruby/core/time/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..9918728c1d
--- /dev/null
+++ b/spec/ruby/core/time/deconstruct_keys_spec.rb
@@ -0,0 +1,43 @@
+require_relative '../../spec_helper'
+
+describe "Time#deconstruct_keys" do
+  it "returns whole hash for nil as an argument" do
+    d = Time.utc(2022, 10, 5, 13, 30)
+    res = { year: 2022, month: 10, day: 5, yday: 278, wday: 3, hour: 13,
+            min: 30, sec: 0, subsec: 0, dst: false, zone: "UTC" }
+    d.deconstruct_keys(nil).should == res
+  end
+
+  it "returns only specified keys" do
+    d = Time.utc(2022, 10, 5, 13, 39)
+    d.deconstruct_keys([:zone, :subsec]).should == { zone: "UTC", subsec: 0 }
+  end
+
+  it "requires one argument" do
+    -> {
+      Time.new(2022, 10, 5, 13, 30).deconstruct_keys
+    }.should.raise(ArgumentError)
+  end
+
+  it "it raises error when argument is neither nil nor array" do
+    d = Time.new(2022, 10, 5, 13, 30)
+
+    -> { d.deconstruct_keys(1) }.should.raise(TypeError, "wrong argument type Integer (expected Array or nil)")
+    -> { d.deconstruct_keys("asd") }.should.raise(TypeError, "wrong argument type String (expected Array or nil)")
+    -> { d.deconstruct_keys(:x) }.should.raise(TypeError, "wrong argument type Symbol (expected Array or nil)")
+    -> { d.deconstruct_keys({}) }.should.raise(TypeError, "wrong argument type Hash (expected Array or nil)")
+  end
+
+  it "returns {} when passed []" do
+    Time.new(2022, 10, 5, 13, 30).deconstruct_keys([]).should == {}
+  end
+
+  it "ignores non-Symbol keys" do
+    Time.new(2022, 10, 5, 13, 30).deconstruct_keys(['year', []]).should == {}
+  end
+
+  it "ignores not existing Symbol keys and processes keys after the first non-existing one" do
+    d = Time.utc(2022, 10, 5, 13, 30)
+    d.deconstruct_keys([:year, :a, :month, :b, :day]).should == { year: 2022, month: 10, day: 5 }
+  end
+end
diff --git a/spec/ruby/core/time/dup_spec.rb b/spec/ruby/core/time/dup_spec.rb
index ee2ff7dbba..33aa1304ef 100644
--- a/spec/ruby/core/time/dup_spec.rb
+++ b/spec/ruby/core/time/dup_spec.rb
@@ -7,7 +7,7 @@ describe "Time#dup" do
   end
 
   it "copies the gmt state flag" do
-    Time.now.gmtime.dup.gmt?.should == true
+    Time.now.gmtime.dup.should.gmt?
   end
 
   it "returns an independent Time object" do
@@ -15,32 +15,32 @@ describe "Time#dup" do
     t2 = t.dup
     t.gmtime
 
-    t2.gmt?.should == false
+    t2.should_not.gmt?
   end
 
   it "returns a subclass instance" do
     c = Class.new(Time)
     t = c.now
 
-    t.should be_an_instance_of(c)
-    t.dup.should be_an_instance_of(c)
+    t.should.instance_of?(c)
+    t.dup.should.instance_of?(c)
   end
 
   it "returns a clone of Time instance" do
     c = Time.dup
     t = c.now
 
-    t.should be_an_instance_of(c)
-    t.should_not be_an_instance_of(Time)
+    t.should.instance_of?(c)
+    t.should_not.instance_of?(Time)
 
-    t.dup.should be_an_instance_of(c)
-    t.dup.should_not be_an_instance_of(Time)
+    t.dup.should.instance_of?(c)
+    t.dup.should_not.instance_of?(Time)
   end
 
   it "does not copy frozen status from the original" do
     t = Time.now
     t.freeze
     t2 = t.dup
-    t2.frozen?.should be_false
+    t2.frozen?.should == false
   end
 end
diff --git a/spec/ruby/core/time/eql_spec.rb b/spec/ruby/core/time/eql_spec.rb
index 2ffb4eec96..b7505969dd 100644
--- a/spec/ruby/core/time/eql_spec.rb
+++ b/spec/ruby/core/time/eql_spec.rb
@@ -2,28 +2,28 @@ require_relative '../../spec_helper'
 
 describe "Time#eql?" do
   it "returns true if self and other have the same whole number of seconds" do
-    Time.at(100).should eql(Time.at(100))
+    Time.at(100).should.eql?(Time.at(100))
   end
 
   it "returns false if self and other have differing whole numbers of seconds" do
-    Time.at(100).should_not eql(Time.at(99))
+    Time.at(100).should_not.eql?(Time.at(99))
   end
 
   it "returns true if self and other have the same number of microseconds" do
-    Time.at(100, 100).should eql(Time.at(100, 100))
+    Time.at(100, 100).should.eql?(Time.at(100, 100))
   end
 
   it "returns false if self and other have differing numbers of microseconds" do
-    Time.at(100, 100).should_not eql(Time.at(100, 99))
+    Time.at(100, 100).should_not.eql?(Time.at(100, 99))
   end
 
   it "returns false if self and other have differing fractional microseconds" do
-    Time.at(100, Rational(100,1000)).should_not eql(Time.at(100, Rational(99,1000)))
+    Time.at(100, Rational(100,1000)).should_not.eql?(Time.at(100, Rational(99,1000)))
   end
 
   it "returns false when given a non-time value" do
-    Time.at(100, 100).should_not eql("100")
-    Time.at(100, 100).should_not eql(100)
-    Time.at(100, 100).should_not eql(100.1)
+    Time.at(100, 100).should_not.eql?("100")
+    Time.at(100, 100).should_not.eql?(100)
+    Time.at(100, 100).should_not.eql?(100.1)
   end
 end
diff --git a/spec/ruby/core/time/fixtures/classes.rb b/spec/ruby/core/time/fixtures/classes.rb
index 1a9511b261..21c4e1effb 100644
--- a/spec/ruby/core/time/fixtures/classes.rb
+++ b/spec/ruby/core/time/fixtures/classes.rb
@@ -59,7 +59,6 @@ module TimeSpecs
   Zone = Struct.new(:std, :dst, :dst_range)
   Zones = {
     "Asia/Colombo" => Zone[Z[5*3600+30*60, "MMT"], nil, nil],
-    "Europe/Kiev" => Zone[Z[2*3600, "EET"], Z[3*3600, "EEST"], 4..10],
     "PST" => Zone[Z[(-9*60*60), "PST"], nil, nil],
   }
 
diff --git a/spec/ruby/core/time/floor_spec.rb b/spec/ruby/core/time/floor_spec.rb
index 763ed1ba51..41e5142b19 100644
--- a/spec/ruby/core/time/floor_spec.rb
+++ b/spec/ruby/core/time/floor_spec.rb
@@ -1,37 +1,36 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.7" do
-  describe "Time#floor" do
-    before do
-      @time = Time.utc(2010, 3, 30, 5, 43, "25.123456789".to_r)
-    end
+describe "Time#floor" do
+  before do
+    @time = Time.utc(2010, 3, 30, 5, 43, "25.123456789".to_r)
+  end
 
-    it "defaults to flooring to 0 places" do
-      @time.floor.should == Time.utc(2010, 3, 30, 5, 43, 25.to_r)
-    end
+  it "defaults to flooring to 0 places" do
+    @time.floor.should == Time.utc(2010, 3, 30, 5, 43, 25.to_r)
+  end
 
-    it "floors to 0 decimal places with an explicit argument" do
-      @time.floor(0).should == Time.utc(2010, 3, 30, 5, 43, 25.to_r)
-    end
+  it "floors to 0 decimal places with an explicit argument" do
+    @time.floor(0).should == Time.utc(2010, 3, 30, 5, 43, 25.to_r)
+  end
 
-    it "floors to 7 decimal places with an explicit argument" do
-      @time.floor(7).should == Time.utc(2010, 3, 30, 5, 43, "25.1234567".to_r)
-    end
+  it "floors to 7 decimal places with an explicit argument" do
+    @time.floor(7).should == Time.utc(2010, 3, 30, 5, 43, "25.1234567".to_r)
+  end
 
-    it "returns an instance of Time, even if #floor is called on a subclass" do
-      subclass = Class.new(Time)
-      instance = subclass.at(0)
-      instance.class.should equal subclass
-      instance.floor.should be_an_instance_of(Time)
-    end
+  it "returns an instance of Time, even if #floor is called on a subclass" do
+    subclass = Class.new(Time)
+    instance = subclass.at(0)
+    instance.class.should.equal? subclass
+    instance.floor.should.instance_of?(Time)
+  end
 
-    it "copies own timezone to the returning value" do
-      @time.zone.should == @time.floor.zone
+  it "copies own timezone to the returning value" do
+    @time.zone.should == @time.floor.zone
 
-      with_timezone "JST-9" do
-        time = Time.at 0, 1
-        time.zone.should == time.floor.zone
-      end
+    time = with_timezone "JST-9" do
+      Time.at 0, 1
     end
+
+    time.zone.should == time.floor.zone
   end
 end
diff --git a/spec/ruby/core/time/friday_spec.rb b/spec/ruby/core/time/friday_spec.rb
index 27f9e1dbe5..8bee7f7558 100644
--- a/spec/ruby/core/time/friday_spec.rb
+++ b/spec/ruby/core/time/friday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#friday?" do
   it "returns true if time represents Friday" do
-    Time.local(2000, 1, 7).friday?.should == true
+    Time.local(2000, 1, 7).should.friday?
   end
 
   it "returns false if time doesn't represent Friday" do
-    Time.local(2000, 1, 1).friday?.should == false
+    Time.local(2000, 1, 1).should_not.friday?
   end
 end
diff --git a/spec/ruby/core/time/getlocal_spec.rb b/spec/ruby/core/time/getlocal_spec.rb
index 7196577dab..7e5334c303 100644
--- a/spec/ruby/core/time/getlocal_spec.rb
+++ b/spec/ruby/core/time/getlocal_spec.rb
@@ -14,6 +14,7 @@ describe "Time#getlocal" do
     t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal(3630)
     t.should == Time.new(2007, 1, 9, 13, 0, 30, 3630)
     t.utc_offset.should == 3630
+    t.zone.should == nil
   end
 
   platform_is_not :windows do
@@ -40,7 +41,7 @@ describe "Time#getlocal" do
   it "returns a Time with a UTC offset of the specified number of Rational seconds" do
     t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal(Rational(7201, 2))
     t.should == Time.new(2007, 1, 9, 13, 0, Rational(1, 2), Rational(7201, 2))
-    t.utc_offset.should eql(Rational(7201, 2))
+    t.utc_offset.should.eql?(Rational(7201, 2))
   end
 
   describe "with an argument that responds to #to_r" do
@@ -49,7 +50,7 @@ describe "Time#getlocal" do
       o.should_receive(:to_r).and_return(Rational(7201, 2))
       t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal(o)
       t.should == Time.new(2007, 1, 9, 13, 0, Rational(1, 2), Rational(7201, 2))
-      t.utc_offset.should eql(Rational(7201, 2))
+      t.utc_offset.should.eql?(Rational(7201, 2))
     end
   end
 
@@ -59,12 +60,24 @@ describe "Time#getlocal" do
     t.utc_offset.should == 3600
   end
 
+  it "returns a Time with a UTC offset specified as +HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("+01:00:01")
+    t.should == Time.new(2007, 1, 9, 13, 0, 1, 3601)
+    t.utc_offset.should == 3601
+  end
+
   it "returns a Time with a UTC offset specified as -HH:MM" do
     t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("-01:00")
     t.should == Time.new(2007, 1, 9, 11, 0, 0, -3600)
     t.utc_offset.should == -3600
   end
 
+  it "returns a Time with a UTC offset specified as -HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0).getlocal("-01:00:01")
+    t.should == Time.new(2007, 1, 9, 10, 59, 59, -3601)
+    t.utc_offset.should == -3601
+  end
+
   describe "with an argument that responds to #to_str" do
     it "coerces using #to_str" do
       o = mock('string')
@@ -77,91 +90,115 @@ describe "Time#getlocal" do
 
   it "raises ArgumentError if the String argument is not of the form (+|-)HH:MM" do
     t = Time.now
-    -> { t.getlocal("3600") }.should raise_error(ArgumentError)
+    -> { t.getlocal("3600") }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the String argument is not in an ASCII-compatible encoding" do
     t = Time.now
-    -> { t.getlocal("-01:00".encode("UTF-16LE")) }.should raise_error(ArgumentError)
+    -> { t.getlocal("-01:00".encode("UTF-16LE")) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value less than or equal to -86400 seconds" do
     t = Time.new
     t.getlocal(-86400 + 1).utc_offset.should == (-86400 + 1)
-    -> { t.getlocal(-86400) }.should raise_error(ArgumentError)
+    -> { t.getlocal(-86400) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value greater than or equal to 86400 seconds" do
     t = Time.new
     t.getlocal(86400 - 1).utc_offset.should == (86400 - 1)
-    -> { t.getlocal(86400) }.should raise_error(ArgumentError)
+    -> { t.getlocal(86400) }.should.raise(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    describe "with a timezone argument" do
-      it "returns a Time in the timezone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
+  it "raises ArgumentError if String argument and hours greater than 23" do
+    -> { Time.now.getlocal("+24:00") }.should.raise(ArgumentError, "utc_offset out of range")
+    -> { Time.now.getlocal("+2400") }.should.raise(ArgumentError, "utc_offset out of range")
 
-        time.zone.should == zone
-        time.utc_offset.should == 5*3600+30*60
-      end
+    -> { Time.now.getlocal("+99:00") }.should.raise(ArgumentError, "utc_offset out of range")
+    -> { Time.now.getlocal("+9900") }.should.raise(ArgumentError, "utc_offset out of range")
+  end
 
-      it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
-        zone = Object.new
-        def zone.utc_to_local(time)
-          time
-        end
-        def zone.local_to_utc(time)
-          time
-        end
+  it "raises ArgumentError if String argument and minutes greater than 59" do
+    -> { Time.now.getlocal("+00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+    -> { Time.now.getlocal("+0060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+    -> { Time.now.getlocal("+00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+    -> { Time.now.getlocal("+0099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+  end
+
+  ruby_bug '#20797', ''...'3.4' do
+    it "raises ArgumentError if String argument and seconds greater than 59" do
+      -> { Time.now.getlocal("+00:00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+      -> { Time.now.getlocal("+000060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+      -> { Time.now.getlocal("+00:00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+      -> { Time.now.getlocal("+000099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+    end
+  end
+
+  describe "with a timezone argument" do
+    it "returns a Time in the timezone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
+
+      time.zone.should == zone
+      time.utc_offset.should == 5*3600+30*60
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
-        }.should_not raise_error
+    it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+      zone = Object.new
+      def zone.utc_to_local(time)
+        time
+      end
+      def zone.local_to_utc(time)
+        time
       end
 
-      it "raises TypeError if timezone does not implement #utc_to_local method" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          time
-        end
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should.is_a?(Time)
+      }.should_not.raise
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
-        }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+    it "raises TypeError if timezone does not implement #utc_to_local method" do
+      zone = Object.new
+      def zone.local_to_utc(time)
+        time
       end
 
-      it "does not raise exception if timezone does not implement #local_to_utc method" do
-        zone = Object.new
-        def zone.utc_to_local(time)
-          time
-        end
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
+      }.should.raise(TypeError, /can't convert \w+ into an exact number/)
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
-        }.should_not raise_error
+    it "does not raise exception if timezone does not implement #local_to_utc method" do
+      zone = Object.new
+      def zone.utc_to_local(time)
+        time
       end
 
-      context "subject's class implements .find_timezone method" do
-        it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
-          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("Asia/Colombo")
-          time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-          time.zone.name.should == "Asia/Colombo"
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should.is_a?(Time)
+      }.should_not.raise
+    end
+
+    context "subject's class implements .find_timezone method" do
+      it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
+        time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("Asia/Colombo")
+        time.zone.should.is_a? TimeSpecs::TimezoneWithName
+        time.zone.name.should == "Asia/Colombo"
 
-          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("some invalid zone name")
-          time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-          time.zone.name.should == "some invalid zone name"
-        end
+        time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("some invalid zone name")
+        time.zone.should.is_a? TimeSpecs::TimezoneWithName
+        time.zone.name.should == "some invalid zone name"
+      end
 
-        it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
-          [Object.new, [], {}, :"some zone"].each do |zone|
-            time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0)
+      it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
+        [Object.new, [], {}, :"some zone"].each do |zone|
+          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0)
 
-            -> {
-              time.getlocal(zone)
-            }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
-          end
+          -> {
+            time.getlocal(zone)
+          }.should.raise(TypeError, /can't convert \w+ into an exact number/)
         end
       end
     end
diff --git a/spec/ruby/core/time/gmt_spec.rb b/spec/ruby/core/time/gmt_spec.rb
index 7e85749d5b..840f59e0e8 100644
--- a/spec/ruby/core/time/gmt_spec.rb
+++ b/spec/ruby/core/time/gmt_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 
 describe "Time#gmt?" do
   it "returns true if time represents a time in UTC (GMT)" do
-    Time.now.gmt?.should == false
-    Time.now.gmtime.gmt?.should == true
+    Time.now.should_not.gmt?
+    Time.now.gmtime.should.gmt?
   end
 end
diff --git a/spec/ruby/core/time/hash_spec.rb b/spec/ruby/core/time/hash_spec.rb
index 577aaf9b0a..1cfc56eab0 100644
--- a/spec/ruby/core/time/hash_spec.rb
+++ b/spec/ruby/core/time/hash_spec.rb
@@ -1,8 +1,8 @@
 require_relative '../../spec_helper'
 
 describe "Time#hash" do
-  it "returns a Fixnum" do
-    Time.at(100).hash.should be_an_instance_of(Fixnum)
+  it "returns an Integer" do
+    Time.at(100).hash.should.instance_of?(Integer)
   end
 
   it "is stable" do
diff --git a/spec/ruby/core/time/inspect_spec.rb b/spec/ruby/core/time/inspect_spec.rb
index 01e1dfdaa6..c3a4519a24 100644
--- a/spec/ruby/core/time/inspect_spec.rb
+++ b/spec/ruby/core/time/inspect_spec.rb
@@ -3,4 +3,31 @@ require_relative 'shared/inspect'
 
 describe "Time#inspect" do
   it_behaves_like :inspect, :inspect
+
+  it "preserves microseconds" do
+    t = Time.utc(2007, 11, 1, 15, 25, 0, 123456)
+    t.inspect.should == "2007-11-01 15:25:00.123456 UTC"
+  end
+
+  it "omits trailing zeros from microseconds" do
+    t = Time.utc(2007, 11, 1, 15, 25, 0, 100000)
+    t.inspect.should == "2007-11-01 15:25:00.1 UTC"
+  end
+
+  it "uses the correct time zone without microseconds" do
+    t = Time.utc(2000, 1, 1)
+    t = t.localtime(9*3600)
+    t.inspect.should == "2000-01-01 09:00:00 +0900"
+  end
+
+  it "uses the correct time zone with microseconds" do
+    t = Time.utc(2000, 1, 1, 0, 0, 0, 123456)
+    t = t.localtime(9*3600)
+    t.inspect.should == "2000-01-01 09:00:00.123456 +0900"
+  end
+
+  it "preserves nanoseconds" do
+    t = Time.utc(2007, 11, 1, 15, 25, 0, 123456.789r)
+    t.inspect.should == "2007-11-01 15:25:00.123456789 UTC"
+  end
 end
diff --git a/spec/ruby/core/time/iso8601_spec.rb b/spec/ruby/core/time/iso8601_spec.rb
new file mode 100644
index 0000000000..ad60c3bb32
--- /dev/null
+++ b/spec/ruby/core/time/iso8601_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/xmlschema'
+
+describe "Time#iso8601" do
+  it_behaves_like :time_xmlschema, :iso8601
+end
diff --git a/spec/ruby/core/time/localtime_spec.rb b/spec/ruby/core/time/localtime_spec.rb
index 2975e112d0..1c0b11b7a6 100644
--- a/spec/ruby/core/time/localtime_spec.rb
+++ b/spec/ruby/core/time/localtime_spec.rb
@@ -12,7 +12,7 @@ describe "Time#localtime" do
 
   it "returns self" do
     t = Time.gm(2007, 1, 9, 12, 0, 0)
-    t.localtime.should equal(t)
+    t.localtime.should.equal?(t)
   end
 
   it "converts time to the UTC offset specified as an Integer number of seconds" do
@@ -26,13 +26,13 @@ describe "Time#localtime" do
     it "does not raise an error if already in the right time zone" do
       time = Time.now
       time.freeze
-      time.localtime.should equal(time)
+      time.localtime.should.equal?(time)
     end
 
-    it "raises a RuntimeError if the time has a different time zone" do
+    it "raises a FrozenError if the time has a different time zone" do
       time = Time.gm(2007, 1, 9, 12, 0, 0)
       time.freeze
-      -> { time.localtime }.should raise_error(RuntimeError)
+      -> { time.localtime }.should.raise(FrozenError)
     end
   end
 
@@ -51,7 +51,7 @@ describe "Time#localtime" do
     t = Time.gm(2007, 1, 9, 12, 0, 0)
     t.localtime(Rational(7201, 2))
     t.should == Time.new(2007, 1, 9, 13, 0, Rational(1, 2), Rational(7201, 2))
-    t.utc_offset.should eql(Rational(7201, 2))
+    t.utc_offset.should.eql?(Rational(7201, 2))
   end
 
   describe "with an argument that responds to #to_r" do
@@ -61,7 +61,7 @@ describe "Time#localtime" do
       t = Time.gm(2007, 1, 9, 12, 0, 0)
       t.localtime(o)
       t.should == Time.new(2007, 1, 9, 13, 0, Rational(1, 2), Rational(7201, 2))
-      t.utc_offset.should eql(Rational(7201, 2))
+      t.utc_offset.should.eql?(Rational(7201, 2))
     end
   end
 
@@ -72,6 +72,13 @@ describe "Time#localtime" do
     t.utc_offset.should == 3600
   end
 
+  it "returns a Time with a UTC offset specified as +HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0)
+    t.localtime("+01:00:01")
+    t.should == Time.new(2007, 1, 9, 13, 0, 1, 3601)
+    t.utc_offset.should == 3601
+  end
+
   it "returns a Time with a UTC offset specified as -HH:MM" do
     t = Time.gm(2007, 1, 9, 12, 0, 0)
     t.localtime("-01:00")
@@ -79,6 +86,51 @@ describe "Time#localtime" do
     t.utc_offset.should == -3600
   end
 
+  it "returns a Time with a UTC offset specified as -HH:MM:SS" do
+    t = Time.gm(2007, 1, 9, 12, 0, 0)
+    t.localtime("-01:00:01")
+    t.should == Time.new(2007, 1, 9, 10, 59, 59, -3601)
+    t.utc_offset.should == -3601
+  end
+
+  it "returns a Time with a UTC offset specified as UTC" do
+    t = Time.new(2007, 1, 9, 12, 0, 0, 3600)
+    t.localtime("UTC")
+    t.utc_offset.should == 0
+  end
+
+  it "returns a Time with a UTC offset specified as A-Z military zone" do
+    t = Time.new(2007, 1, 9, 12, 0, 0, 3600)
+    t.localtime("B")
+    t.utc_offset.should == 3600 * 2
+  end
+
+  it "raises ArgumentError if String argument and hours greater than 23" do
+    -> { Time.now.localtime("+24:00") }.should.raise(ArgumentError, "utc_offset out of range")
+    -> { Time.now.localtime("+2400") }.should.raise(ArgumentError, "utc_offset out of range")
+
+    -> { Time.now.localtime("+99:00") }.should.raise(ArgumentError, "utc_offset out of range")
+    -> { Time.now.localtime("+9900") }.should.raise(ArgumentError, "utc_offset out of range")
+  end
+
+  it "raises ArgumentError if String argument and minutes greater than 59" do
+    -> { Time.now.localtime("+00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+    -> { Time.now.localtime("+0060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+    -> { Time.now.localtime("+00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+    -> { Time.now.localtime("+0099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+  end
+
+  ruby_bug '#20797', ''...'3.4' do
+    it "raises ArgumentError if String argument and seconds greater than 59" do
+      -> { Time.now.localtime("+00:00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+      -> { Time.now.localtime("+000060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+      -> { Time.now.localtime("+00:00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+      -> { Time.now.localtime("+000099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+    end
+  end
+
   platform_is_not :windows do
     it "changes the timezone according to the set one" do
       t = Time.new(2005, 2, 27, 22, 50, 0, -3600)
@@ -116,25 +168,36 @@ describe "Time#localtime" do
     end
   end
 
+  describe "with an argument that responds to #utc_to_local" do
+    it "coerces using #utc_to_local" do
+      o = mock('string')
+      o.should_receive(:utc_to_local).and_return(Time.new(2007, 1, 9, 13, 0, 0, 3600))
+      t = Time.gm(2007, 1, 9, 12, 0, 0)
+      t.localtime(o)
+      t.should == Time.new(2007, 1, 9, 13, 0, 0, 3600)
+      t.utc_offset.should == 3600
+    end
+  end
+
   it "raises ArgumentError if the String argument is not of the form (+|-)HH:MM" do
     t = Time.now
-    -> { t.localtime("3600") }.should raise_error(ArgumentError)
+    -> { t.localtime("3600") }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the String argument is not in an ASCII-compatible encoding" do
     t = Time.now
-    -> { t.localtime("-01:00".encode("UTF-16LE")) }.should raise_error(ArgumentError)
+    -> { t.localtime("-01:00".encode("UTF-16LE")) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value less than or equal to -86400 seconds" do
     t = Time.new
     t.localtime(-86400 + 1).utc_offset.should == (-86400 + 1)
-    -> { t.localtime(-86400) }.should raise_error(ArgumentError)
+    -> { t.localtime(-86400) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value greater than or equal to 86400 seconds" do
     t = Time.new
     t.localtime(86400 - 1).utc_offset.should == (86400 - 1)
-    -> { t.localtime(86400) }.should raise_error(ArgumentError)
+    -> { t.localtime(86400) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/time/minus_spec.rb b/spec/ruby/core/time/minus_spec.rb
index e0fbf94cb0..ee3d8acda8 100644
--- a/spec/ruby/core/time/minus_spec.rb
+++ b/spec/ruby/core/time/minus_spec.rb
@@ -20,18 +20,18 @@ describe "Time#-" do
   end
 
   it "raises a TypeError if given argument is a coercible String" do
-    -> { Time.now - "1" }.should raise_error(TypeError)
-    -> { Time.now - "0.1" }.should raise_error(TypeError)
-    -> { Time.now - "1/3" }.should raise_error(TypeError)
+    -> { Time.now - "1" }.should.raise(TypeError)
+    -> { Time.now - "0.1" }.should.raise(TypeError)
+    -> { Time.now - "1/3" }.should.raise(TypeError)
   end
 
   it "raises TypeError on argument that can't be coerced" do
-    -> { Time.now - Object.new }.should raise_error(TypeError)
-    -> { Time.now - "stuff" }.should raise_error(TypeError)
+    -> { Time.now - Object.new }.should.raise(TypeError)
+    -> { Time.now - "stuff" }.should.raise(TypeError)
   end
 
   it "raises TypeError on nil argument" do
-    -> { Time.now - nil }.should raise_error(TypeError)
+    -> { Time.now - nil }.should.raise(TypeError)
   end
 
   it "tracks microseconds" do
@@ -79,11 +79,11 @@ describe "Time#-" do
   end
 
   it "returns a UTC time if self is UTC" do
-    (Time.utc(2012) - 10).utc?.should == true
+    (Time.utc(2012) - 10).should.utc?
   end
 
   it "returns a non-UTC time if self is non-UTC" do
-    (Time.local(2012) - 10).utc?.should == false
+    (Time.local(2012) - 10).should_not.utc?
   end
 
   it "returns a time with the same fixed offset as self" do
@@ -92,27 +92,25 @@ describe "Time#-" do
 
   it "preserves time zone" do
     time_with_zone = Time.now.utc
-    time_with_zone.zone.should == (time_with_zone - 60*60).zone
+    time_with_zone.zone.should == (time_with_zone - 1).zone
 
     time_with_zone = Time.now
-    time_with_zone.zone.should == (time_with_zone - 60*60).zone
+    time_with_zone.zone.should == (time_with_zone - 1).zone
   end
 
-  ruby_version_is "2.6" do
-    context "zone is a timezone object" do
-      it "preserves time zone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 60*60
+  context "zone is a timezone object" do
+    it "preserves time zone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 1
 
-        time.zone.should == zone
-      end
+      time.zone.should == zone
     end
   end
 
   it "does not return a subclass instance" do
     c = Class.new(Time)
-    x = c.now + 1
-    x.should be_an_instance_of(Time)
+    x = c.now - 1
+    x.should.instance_of?(Time)
   end
 
   it "returns a time with nanoseconds precision between two time objects" do
diff --git a/spec/ruby/core/time/monday_spec.rb b/spec/ruby/core/time/monday_spec.rb
index c5c43a5c3e..47ecaeb1db 100644
--- a/spec/ruby/core/time/monday_spec.rb
+++ b/spec/ruby/core/time/monday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#monday?" do
   it "returns true if time represents Monday" do
-    Time.local(2000, 1, 3).monday?.should == true
+    Time.local(2000, 1, 3).should.monday?
   end
 
   it "returns false if time doesn't represent Monday" do
-    Time.local(2000, 1, 1).monday?.should == false
+    Time.local(2000, 1, 1).should_not.monday?
   end
 end
diff --git a/spec/ruby/core/time/new_spec.rb b/spec/ruby/core/time/new_spec.rb
index dcdd83a085..91ce4b2e3a 100644
--- a/spec/ruby/core/time/new_spec.rb
+++ b/spec/ruby/core/time/new_spec.rb
@@ -15,7 +15,7 @@ end
 
 describe "Time.new with a utc_offset argument" do
   it "returns a non-UTC time" do
-    Time.new(2000, 1, 1, 0, 0, 0, 0).utc?.should == false
+    Time.new(2000, 1, 1, 0, 0, 0, 0).should_not.utc?
   end
 
   it "returns a Time with a UTC offset of the specified number of Integer seconds" do
@@ -31,14 +31,14 @@ describe "Time.new with a utc_offset argument" do
   end
 
   it "returns a Time with a UTC offset of the specified number of Rational seconds" do
-    Time.new(2000, 1, 1, 0, 0, 0, Rational(5, 2)).utc_offset.should eql(Rational(5, 2))
+    Time.new(2000, 1, 1, 0, 0, 0, Rational(5, 2)).utc_offset.should.eql?(Rational(5, 2))
   end
 
   describe "with an argument that responds to #to_r" do
     it "coerces using #to_r" do
       o = mock_numeric('rational')
       o.should_receive(:to_r).and_return(Rational(5, 2))
-      Time.new(2000, 1, 1, 0, 0, 0, o).utc_offset.should eql(Rational(5, 2))
+      Time.new(2000, 1, 1, 0, 0, 0, o).utc_offset.should.eql?(Rational(5, 2))
     end
   end
 
@@ -58,6 +58,30 @@ describe "Time.new with a utc_offset argument" do
     Time.new(2000, 1, 1, 0, 0, 0, "-04:10:43").utc_offset.should == -15043
   end
 
+  it "returns a Time with a UTC offset specified as +HH" do
+    Time.new(2000, 1, 1, 0, 0, 0, "+05").utc_offset.should == 3600 * 5
+  end
+
+  it "returns a Time with a UTC offset specified as -HH" do
+    Time.new(2000, 1, 1, 0, 0, 0, "-05").utc_offset.should == -3600 * 5
+  end
+
+  it "returns a Time with a UTC offset specified as +HHMM" do
+    Time.new(2000, 1, 1, 0, 0, 0, "+0530").utc_offset.should == 19800
+  end
+
+  it "returns a Time with a UTC offset specified as -HHMM" do
+    Time.new(2000, 1, 1, 0, 0, 0, "-0530").utc_offset.should == -19800
+  end
+
+  it "returns a Time with a UTC offset specified as +HHMMSS" do
+    Time.new(2000, 1, 1, 0, 0, 0, "+053037").utc_offset.should == 19837
+  end
+
+  it "returns a Time with a UTC offset specified as -HHMMSS" do
+    Time.new(2000, 1, 1, 0, 0, 0, "-053037").utc_offset.should == -19837
+  end
+
   describe "with an argument that responds to #to_str" do
     it "coerces using #to_str" do
       o = mock('string')
@@ -66,6 +90,48 @@ describe "Time.new with a utc_offset argument" do
     end
   end
 
+  it "returns a Time with UTC offset specified as UTC" do
+    Time.new(2000, 1, 1, 0, 0, 0, "UTC").utc_offset.should == 0
+  end
+
+  it "returns a Time with UTC offset specified as a single letter military timezone" do
+    [
+      ["A", 3600],
+      ["B", 3600 * 2],
+      ["C", 3600 * 3],
+      ["D", 3600 * 4],
+      ["E", 3600 * 5],
+      ["F", 3600 * 6],
+      ["G", 3600 * 7],
+      ["H", 3600 * 8],
+      ["I", 3600 * 9],
+      # J is not supported
+      ["K", 3600 * 10],
+      ["L", 3600 * 11],
+      ["M", 3600 * 12],
+      ["N", 3600 * -1],
+      ["O", 3600 * -2],
+      ["P", 3600 * -3],
+      ["Q", 3600 * -4],
+      ["R", 3600 * -5],
+      ["S", 3600 * -6],
+      ["T", 3600 * -7],
+      ["U", 3600 * -8],
+      ["V", 3600 * -9],
+      ["W", 3600 * -10],
+      ["X", 3600 * -11],
+      ["Y", 3600 * -12],
+      ["Z", 0]
+    ].each do |letter, offset|
+      Time.new(2000, 1, 1, 0, 0, 0, letter).utc_offset.should == offset
+    end
+  end
+
+  it "raises ArgumentError if the string argument is J" do
+    message = '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: J'
+    -> { Time.new(2000, 1, 1, 0, 0, 0, "J") }.should.raise(ArgumentError, message)
+  end
+
   it "returns a local Time if the argument is nil" do
     with_timezone("PST", -8) do
       t = Time.new(2000, 1, 1, 0, 0, 0, nil)
@@ -78,250 +144,596 @@ describe "Time.new with a utc_offset argument" do
   it "disallows a value for minutes greater than 59" do
     -> {
       Time.new(2000, 1, 1, 0, 0, 0, "+01:60")
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       Time.new(2000, 1, 1, 0, 0, 0, "+01:99")
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the String argument is not of the form (+|-)HH:MM" do
-    -> { Time.new(2000, 1, 1, 0, 0, 0, "3600") }.should raise_error(ArgumentError)
+    -> { Time.new(2000, 1, 1, 0, 0, 0, "3600") }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the hour value is greater than 23" do
-    -> { Time.new(2000, 1, 1, 0, 0, 0, "+24:00") }.should raise_error(ArgumentError)
+    -> { Time.new(2000, 1, 1, 0, 0, 0, "+24:00") }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the String argument is not in an ASCII-compatible encoding" do
-    -> { Time.new(2000, 1, 1, 0, 0, 0, "-04:10".encode("UTF-16LE")) }.should raise_error(ArgumentError)
+    # Don't check exception message - it was changed in previous CRuby versions:
+    # - "string contains null byte"
+    # - '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset'
+    -> {
+      Time.new(2000, 1, 1, 0, 0, 0, "-04:10".encode("UTF-16LE"))
+    }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value less than or equal to -86400 seconds" do
     Time.new(2000, 1, 1, 0, 0, 0, -86400 + 1).utc_offset.should == (-86400 + 1)
-    -> { Time.new(2000, 1, 1, 0, 0, 0, -86400) }.should raise_error(ArgumentError)
+    -> { Time.new(2000, 1, 1, 0, 0, 0, -86400) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the argument represents a value greater than or equal to 86400 seconds" do
     Time.new(2000, 1, 1, 0, 0, 0, 86400 - 1).utc_offset.should == (86400 - 1)
-    -> { Time.new(2000, 1, 1, 0, 0, 0, 86400) }.should raise_error(ArgumentError)
-  end
-
-  it "raises ArgumentError if the seconds argument is negative" do
-    -> { Time.new(2000, 1, 1, 0, 0, -1) }.should raise_error(ArgumentError)
+    -> { Time.new(2000, 1, 1, 0, 0, 0, 86400) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if the utc_offset argument is greater than or equal to 10e9" do
-    -> { Time.new(2000, 1, 1, 0, 0, 0, 1000000000) }.should raise_error(ArgumentError)
+    -> { Time.new(2000, 1, 1, 0, 0, 0, 1000000000) }.should.raise(ArgumentError)
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Time.new with a timezone argument" do
-    it "returns a Time in the timezone" do
-      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+# The method #local_to_utc is tested only here because Time.new is the only method that calls #local_to_utc.
+describe "Time.new with a timezone argument" do
+  it "returns a Time in the timezone" do
+    zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+    time = Time.new(2000, 1, 1, 12, 0, 0, zone)
 
-      time.zone.should == zone
-      time.utc_offset.should == 5*3600+30*60
+    time.zone.should == zone
+    time.utc_offset.should == 5*3600+30*60
+    time.wday.should == 6
+    time.yday.should == 1
+  end
+
+  it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+    zone = Object.new
+    def zone.utc_to_local(time)
+      time
+    end
+    def zone.local_to_utc(time)
+      time
+    end
+
+    Time.new(2000, 1, 1, 12, 0, 0, zone).should.is_a?(Time)
+  end
+
+  it "raises TypeError if timezone does not implement #local_to_utc method" do
+    zone = Object.new
+    def zone.utc_to_local(time)
+      time
+    end
+
+    -> {
+      Time.new(2000, 1, 1, 12, 0, 0, zone)
+    }.should.raise(TypeError, /can't convert Object into an exact number/)
+  end
+
+  it "does not raise exception if timezone does not implement #utc_to_local method" do
+    zone = Object.new
+    def zone.local_to_utc(time)
+      time
     end
 
-    it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+    Time.new(2000, 1, 1, 12, 0, 0, zone).should.is_a?(Time)
+  end
+
+  # The result also should be a Time or Time-like object (not necessary to be the same class)
+  # or respond to #to_int method. The zone of the result is just ignored.
+  describe "returned value by #utc_to_local and #local_to_utc methods" do
+    it "could be Time instance" do
       zone = Object.new
-      def zone.utc_to_local(time)
-        time
-      end
-      def zone.local_to_utc(time)
-        time
+      def zone.local_to_utc(t)
+        time = Time.utc(t.year, t.mon, t.day, t.hour, t.min, t.sec)
+        time - 60 * 60 # - 1 hour
       end
 
-      -> {
-        Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-      }.should_not raise_error
+      Time.new(2000, 1, 1, 12, 0, 0, zone).should.is_a?(Time)
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
     end
 
-    it "raises TypeError if timezone does not implement #local_to_utc method" do
+    it "could be Time subclass instance" do
       zone = Object.new
-      def zone.utc_to_local(time)
-        time
+      def zone.local_to_utc(t)
+        time = Time.utc(t.year, t.mon, t.day, t.hour, t.min, t.sec)
+        time -= 60 * 60 # - 1 hour
+        Class.new(Time).utc(time.year, time.mon, time.day, time.hour, t.min, t.sec)
       end
 
-      -> {
-        Time.new(2000, 1, 1, 12, 0, 0, zone)
-      }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+      Time.new(2000, 1, 1, 12, 0, 0, zone).should.is_a?(Time)
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
     end
 
-    it "does not raise exception if timezone does not implement #utc_to_local method" do
+    it "could be any object with #to_i method" do
       zone = Object.new
       def zone.local_to_utc(time)
-        time
+        obj = Object.new
+        obj.singleton_class.define_method(:to_i) { time.to_i - 60*60 }
+        obj
       end
 
-      -> {
-        Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-      }.should_not raise_error
+      Time.new(2000, 1, 1, 12, 0, 0, zone).should.is_a?(Time)
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
     end
 
-    # The result also should be a Time or Time-like object (not necessary to be the same class)
-    # The zone of the result is just ignored
-    describe "returned value by #utc_to_local and #local_to_utc methods" do
-      it "could be Time instance" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Time.utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
-        end
+    it "could have any #zone and #utc_offset because they are ignored if it isn't an instance of Time" do
+      zone = Object.new
+      def zone.local_to_utc(time)
+        Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'America/New_York', -5*60*60)
+      end
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
 
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
+      zone = Object.new
+      def zone.local_to_utc(time)
+        Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'Asia/Tokyo', 9*60*60)
       end
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
+    end
 
-      it "could be Time subclass instance" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Class.new(Time).utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
-        end
+    it "cannot have arbitrary #utc_offset if it is an instance of Time" do
+      zone = Object.new
+      def zone.local_to_utc(t)
+        Time.new(t.year, t.mon, t.mday, t.hour, t.min, t.sec, 9*60*60)
+      end
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 9*60*60
+    end
 
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
+    it "raises ArgumentError if difference between argument and result is too large" do
+      zone = Object.new
+      def zone.local_to_utc(t)
+        Time.utc(t.year, t.mon, t.day + 1, t.hour, t.min, t.sec)
       end
 
-      it "could be any object with #to_i method" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i).new(time.to_i - 60*60)
-        end
+      -> {
+        Time.new(2000, 1, 1, 12, 0, 0, zone)
+      }.should.raise(ArgumentError, "utc_offset out of range")
+    end
+  end
 
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
-      end
+  # https://github.com/ruby/ruby/blob/v2_6_0/time.c#L5330
+  #
+  # Time-like argument to these methods is similar to a Time object in UTC without sub-second;
+  # it has attribute readers for the parts, e.g. year, month, and so on, and epoch time readers, to_i
+  #
+  # The sub-second attributes are fixed as 0, and utc_offset, zone, isdst, and their aliases are same as a Time object in UTC
+  describe "Time-like argument of #utc_to_local and #local_to_utc methods" do
+    before do
+      @obj = TimeSpecs::TimeLikeArgumentRecorder.result
+      @obj.should_not == nil
+    end
 
-      it "could have any #zone and #utc_offset because they are ignored" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'America/New_York', -5*60*60)
-        end
-        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
-
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'Asia/Tokyo', 9*60*60)
-        end
-        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
+    it "implements subset of Time methods" do
+      # List only methods that are explicitly documented.
+      [
+        :year, :mon, :mday, :hour, :min, :sec, :to_i, :isdst
+      ].each do |name|
+        @obj.respond_to?(name).should == true
       end
+    end
 
-      it "leads to raising Argument error if difference between argument and result is too large" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Time.utc(t.year, t.mon, t.day + 1, t.hour, t.min, t.sec)
-        end
+    it "has attribute values the same as a Time object in UTC" do
+      @obj.usec.should == 0
+      @obj.nsec.should == 0
+      @obj.subsec.should == 0
+      @obj.tv_usec.should == 0
+      @obj.tv_nsec.should == 0
 
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone)
-        }.should raise_error(ArgumentError, "utc_offset out of range")
-      end
+      @obj.utc_offset.should == 0
+      @obj.zone.should == "UTC"
+      @obj.isdst.should == Time.new.utc.isdst
     end
+  end
 
-    # https://github.com/ruby/ruby/blob/v2_6_0/time.c#L5330
-    #
-    # Time-like argument to these methods is similar to a Time object in UTC without sub-second;
-    # it has attribute readers for the parts, e.g. year, month, and so on, and epoch time readers, to_i
-    #
-    # The sub-second attributes are fixed as 0, and utc_offset, zone, isdst, and their aliases are same as a Time object in UTC
-    describe "Time-like argument of #utc_to_local and #local_to_utc methods" do
-      before do
-        @obj = TimeSpecs::TimeLikeArgumentRecorder.result
-        @obj.should_not == nil
-      end
+  context "#name method" do
+    it "uses the optional #name method for marshaling" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+      time_loaded = Marshal.load(Marshal.dump(time))
 
-      it "implements subset of Time methods" do
-        [
-          :year, :mon, :month, :mday, :hour, :min, :sec,
-          :tv_sec, :tv_usec, :usec, :tv_nsec, :nsec, :subsec,
-          :to_i, :to_f, :to_r, :+, :-,
-          :isdst, :dst?, :zone, :gmtoff, :gmt_offset, :utc_offset, :utc?, :gmt?,
-          :to_s, :inspect, :to_a, :to_time,
-        ].each do |name|
-          @obj.respond_to?(name).should == true
-        end
-      end
+      time_loaded.zone.should == "Asia/Colombo"
+      time_loaded.utc_offset.should == 5*3600+30*60
+    end
 
-      it "has attribute values the same as a Time object in UTC" do
-        @obj.usec.should == 0
-        @obj.nsec.should == 0
-        @obj.subsec.should == 0
-        @obj.tv_usec.should == 0
-        @obj.tv_nsec.should == 0
+    it "cannot marshal Time if #name method isn't implemented" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
 
-        @obj.utc_offset.should == 0
-        @obj.zone.should == "UTC"
-        @obj.isdst.should == Time.new.utc.isdst
-      end
+      -> {
+        Marshal.dump(time)
+      }.should.raise(NoMethodError, /undefined method [`']name' for/)
     end
+  end
 
-    context "#name method" do
-      it "uses the optional #name method for marshaling" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = Time.new(2000, 1, 1, 12, 0, 0, zone)
-        time_loaded = Marshal.load(Marshal.dump(time))
+  it "the #abbr method is used by '%Z' in #strftime" do
+    zone = TimeSpecs::TimezoneWithAbbr.new(name: "Asia/Colombo")
+    time = Time.new(2000, 1, 1, 12, 0, 0, zone)
 
-        time_loaded.zone.should == "Asia/Colombo"
-        time_loaded.utc_offset.should == 5*3600+30*60
-      end
+    time.strftime("%Z").should == "MMT"
+  end
 
-      it "cannot marshal Time if #name method isn't implemented" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+  # At loading marshaled data, a timezone name will be converted to a timezone object
+  # by find_timezone class method, if the method is defined.
+  # Similarly, that class method will be called when a timezone argument does not have
+  # the necessary methods mentioned above.
+  context "subject's class implements .find_timezone method" do
+    it "calls .find_timezone to build a time object at loading marshaled data" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
+      time_loaded = Marshal.load(Marshal.dump(time))
+
+      time_loaded.zone.should.is_a? TimeSpecs::TimezoneWithName
+      time_loaded.zone.name.should == "Asia/Colombo"
+      time_loaded.utc_offset.should == 5*3600+30*60
+    end
+
+    it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "Asia/Colombo")
+      time.zone.should.is_a? TimeSpecs::TimezoneWithName
+      time.zone.name.should == "Asia/Colombo"
+
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "some invalid zone name")
+      time.zone.should.is_a? TimeSpecs::TimezoneWithName
+      time.zone.name.should == "some invalid zone name"
+    end
 
+    it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
+      [Object.new, [], {}, :"some zone"].each do |zone|
         -> {
-          Marshal.dump(time)
-        }.should raise_error(NoMethodError, /undefined method `name' for/)
+          TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
+        }.should.raise(TypeError, /can't convert \w+ into an exact number/)
       end
     end
+  end
 
-    it "the #abbr method is used by '%Z' in #strftime" do
-      zone = TimeSpecs::TimezoneWithAbbr.new(name: "Asia/Colombo")
-      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+  describe ":in keyword argument" do
+    it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: "+05:00")
+
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: "-09:00")
 
-      time.strftime("%Z").should == "MMT"
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: "-09:00:01")
+
+      time.utc_offset.should == -(9*60*60 + 1)
+      time.zone.should == nil
     end
 
-    # At loading marshaled data, a timezone name will be converted to a timezone object
-    # by find_timezone class method, if the method is defined.
-    # Similary, that class method will be called when a timezone argument does not have
-    # the necessary methods mentioned above.
-    context "subject's class implements .find_timezone method" do
-      it "calls .find_timezone to build a time object at loading marshaled data" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
-        time_loaded = Marshal.load(Marshal.dump(time))
+    it "could be UTC offset as a number of seconds" do
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: 5*60*60)
 
-        time_loaded.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time_loaded.zone.name.should == "Asia/Colombo"
-        time_loaded.utc_offset.should == 5*3600+30*60
-      end
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: -9*60*60)
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+    end
+
+    it "returns a Time with UTC offset specified as a single letter military timezone" do
+      Time.new(2000, 1, 1, 0, 0, 0, in: "W").utc_offset.should == 3600 * -10
+    end
+
+    it "could be a timezone object" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: zone)
+
+      time.utc_offset.should == 5*3600+30*60
+      time.zone.should == zone
+
+      zone = TimeSpecs::TimezoneWithName.new(name: "PST")
+      time = Time.new(2000, 1, 1, 12, 0, 0, in: zone)
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == zone
+    end
+
+    it "allows omitting minor arguments" do
+      Time.new(2000, 1, 1, 12, 1, 1, in: "+05:00").should == Time.new(2000, 1, 1, 12, 1, 1, "+05:00")
+      Time.new(2000, 1, 1, 12, 1, in: "+05:00").should == Time.new(2000, 1, 1, 12, 1, 0, "+05:00")
+      Time.new(2000, 1, 1, 12, in: "+05:00").should == Time.new(2000, 1, 1, 12, 0, 0, "+05:00")
+      Time.new(2000, 1, 1, in: "+05:00").should == Time.new(2000, 1, 1, 0, 0, 0, "+05:00")
+      Time.new(2000, 1, in: "+05:00").should == Time.new(2000, 1, 1, 0, 0, 0, "+05:00")
+      Time.new(2000, in: "+05:00").should == Time.new(2000, 1, 1, 0, 0, 0, "+05:00")
+      Time.new(in: "+05:00").should be_close(Time.now.getlocal("+05:00"), TIME_TOLERANCE)
+    end
+
+    it "converts to a provided timezone if all the positional arguments are omitted" do
+      Time.new(in: "+05:00").utc_offset.should == 5*3600
+    end
+
+    it "raises ArgumentError if format is invalid" do
+      -> { Time.new(2000, 1, 1, 12, 0, 0, in: "+09:99") }.should.raise(ArgumentError)
+      -> { Time.new(2000, 1, 1, 12, 0, 0, in: "ABC") }.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError if two offset arguments are given" do
+      -> {
+        Time.new(2000, 1, 1, 12, 0, 0, "+05:00", in: "+05:00")
+      }.should.raise(ArgumentError, "timezone argument given as positional and keyword arguments")
+    end
+  end
+
+  describe "Time.new with a String argument" do
+    it "parses an ISO-8601 like format" do
+      t = Time.utc(2020, 12, 24, 15, 56, 17)
+
+      Time.new("2020-12-24T15:56:17Z").should == t
+      Time.new("2020-12-25 00:56:17 +09:00").should == t
+      Time.new("2020-12-25 00:57:47 +09:01:30").should == t
+      Time.new("2020-12-25 00:56:17 +0900").should == t
+      Time.new("2020-12-25 00:57:47 +090130").should == t
+      Time.new("2020-12-25T00:56:17+09:00").should == t
+
+      Time.new("2020-12-25T00:56:17.123456+09:00").should == Time.utc(2020, 12, 24, 15, 56, 17, 123456)
+    end
+
+    it "accepts precision keyword argument and truncates specified digits of sub-second part" do
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00").subsec.should == 0.123456789r
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: nil).subsec.should == 0.123456789876r
+      Time.new("2021-12-25 00:00:00 +09:00", precision: 0).subsec.should == 0
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: -1).subsec.should == 0.123456789876r
+    end
+
+    it "returns Time in local timezone if not provided in the String argument" do
+      Time.new("2021-12-25 00:00:00").zone.should == Time.new(2021, 12, 25).zone
+      Time.new("2021-12-25 00:00:00").utc_offset.should == Time.new(2021, 12, 25).utc_offset
+    end
+
+    it "returns Time in timezone specified in the String argument" do
+      Time.new("2021-12-25 00:00:00 +05:00").to_s.should == "2021-12-25 00:00:00 +0500"
+    end
+
+    it "returns Time in timezone specified in the String argument even if the in keyword argument provided" do
+      Time.new("2021-12-25 00:00:00 +09:00", in: "-01:00").to_s.should == "2021-12-25 00:00:00 +0900"
+    end
+
+    it "returns Time in timezone specified with in keyword argument if timezone isn't provided in the String argument" do
+      Time.new("2021-12-25 00:00:00", in: "-01:00").to_s.should == "2021-12-25 00:00:00 -0100"
+    end
+
+    it "returns Time of Jan 1 for string with just year" do
+      Time.new("2021").should == Time.new(2021, 1, 1)
+      Time.new("2021").zone.should == Time.new(2021, 1, 1).zone
+      Time.new("2021").utc_offset.should == Time.new(2021, 1, 1).utc_offset
+    end
+
+    it "returns Time of Jan 1 for string with just year in timezone specified with in keyword argument" do
+      Time.new("2021", in: "+17:00").to_s.should == "2021-01-01 00:00:00 +1700"
+    end
+
+    it "converts precision keyword argument into Integer if is not nil" do
+      obj = Object.new
+      def obj.to_int; 3; end
+
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: 1.2).subsec.should == 0.1r
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: obj).subsec.should == 0.123r
+      Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: 3r).subsec.should == 0.123r
+    end
+
+    it "returns Time with correct subseconds when given seconds fraction is shorted than 6 digits" do
+      Time.new("2020-12-25T00:56:17.123 +09:00").nsec.should == 123000000
+      Time.new("2020-12-25T00:56:17.123 +09:00").usec.should == 123000
+      Time.new("2020-12-25T00:56:17.123 +09:00").subsec.should == 0.123
+    end
+
+    it "returns Time with correct subseconds when given seconds fraction is milliseconds" do
+      Time.new("2020-12-25T00:56:17.123456 +09:00").nsec.should == 123456000
+      Time.new("2020-12-25T00:56:17.123456 +09:00").usec.should == 123456
+      Time.new("2020-12-25T00:56:17.123456 +09:00").subsec.should == 0.123456
+    end
 
-      it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "Asia/Colombo")
-        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time.zone.name.should == "Asia/Colombo"
+    it "returns Time with correct subseconds when given seconds fraction is longer that 6 digits but shorted than 9 digits" do
+      Time.new("2020-12-25T00:56:17.12345678 +09:00").nsec.should == 123456780
+      Time.new("2020-12-25T00:56:17.12345678 +09:00").usec.should == 123456
+      Time.new("2020-12-25T00:56:17.12345678 +09:00").subsec.should == 0.12345678
+    end
+
+    it "returns Time with correct subseconds when given seconds fraction is nanoseconds" do
+      Time.new("2020-12-25T00:56:17.123456789 +09:00").nsec.should == 123456789
+      Time.new("2020-12-25T00:56:17.123456789 +09:00").usec.should == 123456
+      Time.new("2020-12-25T00:56:17.123456789 +09:00").subsec.should == 0.123456789
+    end
+
+    it "returns Time with correct subseconds when given seconds fraction is longer than 9 digits" do
+      Time.new("2020-12-25T00:56:17.123456789876 +09:00").nsec.should == 123456789
+      Time.new("2020-12-25T00:56:17.123456789876 +09:00").usec.should == 123456
+      Time.new("2020-12-25T00:56:17.123456789876 +09:00").subsec.should == 0.123456789
+    end
+
+    it "raise TypeError is can't convert precision keyword argument into Integer" do
+      -> {
+        Time.new("2021-12-25 00:00:00.123456789876 +09:00", precision: "")
+      }.should.raise(TypeError, "no implicit conversion of String into Integer")
+    end
+
+    it "raises ArgumentError if part of time string is missing" do
+      -> {
+        Time.new("2020-12-25 00:56 +09:00")
+      }.should.raise(ArgumentError, /missing sec part: 00:56 |can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00 +09:00")
+      }.should.raise(ArgumentError, /missing min part: 00 |can't parse:/)
+    end
+
+    it "raises ArgumentError if the time part is missing" do
+      -> {
+        Time.new("2020-12-25")
+      }.should.raise(ArgumentError, /no time information|can't parse:/)
+    end
+
+    it "raises ArgumentError if day is missing" do
+      -> {
+        Time.new("2020-12")
+      }.should.raise(ArgumentError, /no time information|can't parse:/)
+    end
+
+    it "raises ArgumentError if subsecond is missing after dot" do
+      -> {
+        Time.new("2020-12-25 00:56:17. +0900")
+      }.should.raise(ArgumentError, /subsecond expected after dot: 00:56:17. |can't parse:/)
+    end
+
+    it "raises ArgumentError if String argument is not in the supported format" do
+      -> {
+        Time.new("021-12-25 00:00:00.123456 +09:00")
+      }.should.raise(ArgumentError, /year must be 4 or more digits: 021|can't parse:/)
+
+      -> {
+        Time.new("2020-012-25 00:56:17 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits mon is expected after [`']-': -012-25 00:\z|can't parse:/)
+
+      -> {
+        Time.new("2020-2-25 00:56:17 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits mon is expected after [`']-': -2-25 00:56\z|can't parse:/)
 
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "some invalid zone name")
-        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time.zone.name.should == "some invalid zone name"
+      -> {
+        Time.new("2020-12-215 00:56:17 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits mday is expected after [`']-': -215 00:56:\z|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 000:56:17 +0900")
+      }.should.raise(ArgumentError, /two digits hour is expected:  000:56:17 |can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 0:56:17 +0900")
+      }.should.raise(ArgumentError, /two digits hour is expected:  0:56:17 \+0|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00:516:17 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits min is expected after [`']:': :516:17 \+09\z|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00:6:17 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits min is expected after [`']:': :6:17 \+0900\z|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00:56:137 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits sec is expected after [`']:': :137 \+0900\z|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00:56:7 +0900")
+      }.should.raise(ArgumentError, /\Atwo digits sec is expected after [`']:': :7 \+0900\z|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00:56. +0900")
+      }.should.raise(ArgumentError, /fraction min is not supported: 00:56\.|can't parse:/)
+
+      -> {
+        Time.new("2020-12-25 00. +0900")
+      }.should.raise(ArgumentError, /fraction hour is not supported: 00\.|can't parse:/)
+    end
+
+    it "raises ArgumentError if date/time parts values are not valid" do
+      -> {
+        Time.new("2020-13-25 00:56:17 +09:00")
+      }.should.raise(ArgumentError, /(mon|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-32 00:56:17 +09:00")
+      }.should.raise(ArgumentError, /(mday|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-25 25:56:17 +09:00")
+      }.should.raise(ArgumentError, /(hour|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-25 00:61:17 +09:00")
+      }.should.raise(ArgumentError, /(min|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-25 00:56:61 +09:00")
+      }.should.raise(ArgumentError, /(sec|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-25 00:56:17 +23:59:60")
+      }.should.raise(ArgumentError, /utc_offset|argument out of range/)
+
+      -> {
+        Time.new("2020-12-25 00:56:17 +24:00")
+      }.should.raise(ArgumentError, /(utc_offset|argument) out of range/)
+
+      -> {
+        Time.new("2020-12-25 00:56:17 +23:61")
+      }.should.raise(ArgumentError, /utc_offset/)
+
+      ruby_bug '#20797', ''...'3.4' do
+        -> {
+          Time.new("2020-12-25 00:56:17 +00:23:61")
+        }.should.raise(ArgumentError, /utc_offset/)
       end
+    end
+
+    it "raises ArgumentError if utc offset parts are not valid" do
+      -> { Time.new("2020-12-25 00:56:17 +24:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.new("2020-12-25 00:56:17 +2400") }.should.raise(ArgumentError, "utc_offset out of range")
+
+      -> { Time.new("2020-12-25 00:56:17 +99:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.new("2020-12-25 00:56:17 +9900") }.should.raise(ArgumentError, "utc_offset out of range")
+
+      -> { Time.new("2020-12-25 00:56:17 +00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+      -> { Time.new("2020-12-25 00:56:17 +0060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+      -> { Time.new("2020-12-25 00:56:17 +00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+      -> { Time.new("2020-12-25 00:56:17 +0099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+
+      ruby_bug '#20797', ''...'3.4' do
+        -> { Time.new("2020-12-25 00:56:17 +00:00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+        -> { Time.new("2020-12-25 00:56:17 +000060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
 
-      it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
-        [Object.new, [], {}, :"some zone"].each do |zone|
-          -> {
-            TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
-          }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
-        end
+        -> { Time.new("2020-12-25 00:56:17 +00:00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+        -> { Time.new("2020-12-25 00:56:17 +000099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
       end
     end
+
+    it "raises ArgumentError if string has not ascii-compatible encoding" do
+      -> {
+        Time.new("2021-11-31 00:00:60 +09:00".encode("utf-32le"))
+      }.should.raise(ArgumentError, "time string should have ASCII compatible encoding")
+    end
+
+    it "raises ArgumentError if string doesn't start with year" do
+      -> {
+        Time.new("a\nb")
+      }.should.raise(ArgumentError, "can't parse: \"a\\nb\"")
+    end
+
+    it "raises ArgumentError if string has extra characters after offset" do
+      -> {
+        Time.new("2021-11-31 00:00:59 +09:00 abc")
+      }.should.raise(ArgumentError, /can't parse.+ abc/)
+    end
+
+    it "raises ArgumentError when there are leading space characters" do
+      -> { Time.new(" 2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("\t2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("\n2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("\v2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("\f2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("\r2020-12-02 00:00:00") }.should.raise(ArgumentError, /can't parse/)
+    end
+
+    it "raises ArgumentError when there are trailing whitespaces" do
+      -> { Time.new("2020-12-02 00:00:00 ") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("2020-12-02 00:00:00\t") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("2020-12-02 00:00:00\n") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("2020-12-02 00:00:00\v") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("2020-12-02 00:00:00\f") }.should.raise(ArgumentError, /can't parse/)
+      -> { Time.new("2020-12-02 00:00:00\r") }.should.raise(ArgumentError, /can't parse/)
+    end
   end
 end
diff --git a/spec/ruby/core/time/now_spec.rb b/spec/ruby/core/time/now_spec.rb
index 7dc7951996..533cf68380 100644
--- a/spec/ruby/core/time/now_spec.rb
+++ b/spec/ruby/core/time/now_spec.rb
@@ -3,4 +3,179 @@ require_relative 'shared/now'
 
 describe "Time.now" do
   it_behaves_like :time_now, :now
+
+  describe ":in keyword argument" do
+    it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
+      time = Time.now(in: "+05:00")
+
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+
+      time = Time.now(in: "-09:00")
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+
+      time = Time.now(in: "-09:00:01")
+
+      time.utc_offset.should == -(9*60*60 + 1)
+      time.zone.should == nil
+    end
+
+    it "could be UTC offset as a number of seconds" do
+      time = Time.now(in: 5*60*60)
+
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+
+      time = Time.now(in: -9*60*60)
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+    end
+
+    it "returns a Time with UTC offset specified as a single letter military timezone" do
+      Time.now(in: "W").utc_offset.should == 3600 * -10
+    end
+
+    it "could be a timezone object" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.now(in: zone)
+
+      time.utc_offset.should == 5*3600+30*60
+      time.zone.should == zone
+
+      zone = TimeSpecs::TimezoneWithName.new(name: "PST")
+      time = Time.now(in: zone)
+
+      time.utc_offset.should == -9*60*60
+      time.zone.should == zone
+    end
+
+    it "raises ArgumentError if format is invalid" do
+      -> { Time.now(in: "+09:99") }.should.raise(ArgumentError)
+      -> { Time.now(in: "ABC") }.should.raise(ArgumentError)
+    end
+
+    it "raises ArgumentError if String argument and hours greater than 23" do
+      -> { Time.now(in: "+24:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.now(in: "+2400") }.should.raise(ArgumentError, "utc_offset out of range")
+
+      -> { Time.now(in: "+99:00") }.should.raise(ArgumentError, "utc_offset out of range")
+      -> { Time.now(in: "+9900") }.should.raise(ArgumentError, "utc_offset out of range")
+    end
+
+    it "raises ArgumentError if String argument and minutes greater than 59" do
+      -> { Time.now(in: "+00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:60')
+      -> { Time.now(in: "+0060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0060')
+
+      -> { Time.now(in: "+00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:99')
+      -> { Time.now(in: "+0099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +0099')
+    end
+
+    ruby_bug '#20797', ''...'3.4' do
+      it "raises ArgumentError if String argument and seconds greater than 59" do
+        -> { Time.now(in: "+00:00:60") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:60')
+        -> { Time.now(in: "+000060") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000060')
+
+        -> { Time.now(in: "+00:00:99") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +00:00:99')
+        -> { Time.now(in: "+000099") }.should.raise(ArgumentError, '"+HH:MM", "-HH:MM", "UTC" or "A".."I","K".."Z" expected for utc_offset: +000099')
+      end
+    end
+  end
+
+  describe "Timezone object" do # https://bugs.ruby-lang.org/issues/17485
+    it "raises TypeError if timezone does not implement #utc_to_local method" do
+      zone = Object.new
+      def zone.local_to_utc(time)
+        time
+      end
+
+      -> {
+        Time.now(in: zone)
+      }.should.raise(TypeError, /can't convert Object into an exact number/)
+    end
+
+    it "does not raise exception if timezone does not implement #local_to_utc method" do
+      zone = Object.new
+      def zone.utc_to_local(time)
+        time
+      end
+
+      Time.now(in: zone).should.is_a?(Time)
+    end
+
+    # The result also should be a Time or Time-like object (not necessary to be the same class)
+    # or Integer. The zone of the result is just ignored.
+    describe "returned value by #utc_to_local and #local_to_utc methods" do
+      it "could be Time instance" do
+        zone = Object.new
+        def zone.utc_to_local(t)
+          time = Time.new(t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset)
+          time + 60 * 60 # + 1 hour
+        end
+
+        Time.now(in: zone).should.is_a?(Time)
+        Time.now(in: zone).utc_offset.should == 3600
+      end
+
+      it "could be Time subclass instance" do
+        zone = Object.new
+        def zone.utc_to_local(t)
+          time = Time.new(t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset)
+          time += 60 * 60 # + 1 hour
+
+          Class.new(Time).new(time.year, time.mon, time.day, time.hour, time.min, time.sec, time.utc_offset)
+        end
+
+        Time.now(in: zone).should.is_a?(Time)
+        Time.now(in: zone).utc_offset.should == 3600
+      end
+
+      it "could be Integer" do
+        zone = Object.new
+        def zone.utc_to_local(time)
+          time.to_i + 60*60
+        end
+
+        Time.now(in: zone).should.is_a?(Time)
+        Time.now(in: zone).utc_offset.should == 60*60
+      end
+
+      it "could have any #zone and #utc_offset because they are ignored" do
+        zone = Object.new
+        def zone.utc_to_local(t)
+          Struct.new(:year, :mon, :mday, :hour, :min, :sec, :isdst, :to_i, :zone, :utc_offset) # rubocop:disable Lint/StructNewOverride
+                .new(t.year, t.mon, t.mday, t.hour, t.min, t.sec, t.isdst, t.to_i, 'America/New_York', -5*60*60)
+        end
+        Time.now(in: zone).utc_offset.should == 0
+
+        zone = Object.new
+        def zone.utc_to_local(t)
+          Struct.new(:year, :mon, :mday, :hour, :min, :sec, :isdst, :to_i, :zone, :utc_offset) # rubocop:disable Lint/StructNewOverride
+                .new(t.year, t.mon, t.mday, t.hour, t.min, t.sec, t.isdst, t.to_i, 'Asia/Tokyo', 9*60*60)
+        end
+        Time.now(in: zone).utc_offset.should == 0
+
+        zone = Object.new
+        def zone.utc_to_local(t)
+          Time.new(t.year, t.mon, t.mday, t.hour, t.min, t.sec, 9*60*60)
+        end
+        Time.now(in: zone).utc_offset.should == 0
+      end
+
+      it "raises ArgumentError if difference between argument and result is too large" do
+        zone = Object.new
+        def zone.utc_to_local(t)
+          time = Time.utc(t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset)
+          time -= 24 * 60 * 60 # - 1 day
+          Time.utc(time.year, time.mon, time.day, time.hour, time.min, time.sec, time.utc_offset)
+        end
+
+        -> {
+          Time.now(in: zone)
+        }.should.raise(ArgumentError, "utc_offset out of range")
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/time/plus_spec.rb b/spec/ruby/core/time/plus_spec.rb
index 0a9984f180..6bd01bcdf3 100644
--- a/spec/ruby/core/time/plus_spec.rb
+++ b/spec/ruby/core/time/plus_spec.rb
@@ -17,9 +17,9 @@ describe "Time#+" do
   end
 
   it "raises a TypeError if given argument is a coercible String" do
-    -> { Time.now + "1" }.should raise_error(TypeError)
-    -> { Time.now + "0.1" }.should raise_error(TypeError)
-    -> { Time.now + "1/3" }.should raise_error(TypeError)
+    -> { Time.now + "1" }.should.raise(TypeError)
+    -> { Time.now + "0.1" }.should.raise(TypeError)
+    -> { Time.now + "1/3" }.should.raise(TypeError)
   end
 
   it "increments the time by the specified amount as rational numbers" do
@@ -32,16 +32,16 @@ describe "Time#+" do
   end
 
   it "raises TypeError on argument that can't be coerced into Rational" do
-    -> { Time.now + Object.new }.should raise_error(TypeError)
-    -> { Time.now + "stuff" }.should raise_error(TypeError)
+    -> { Time.now + Object.new }.should.raise(TypeError)
+    -> { Time.now + "stuff" }.should.raise(TypeError)
   end
 
   it "returns a UTC time if self is UTC" do
-    (Time.utc(2012) + 10).utc?.should == true
+    (Time.utc(2012) + 10).should.utc?
   end
 
   it "returns a non-UTC time if self is non-UTC" do
-    (Time.local(2012) + 10).utc?.should == false
+    (Time.local(2012) + 10).should_not.utc?
   end
 
   it "returns a time with the same fixed offset as self" do
@@ -50,35 +50,33 @@ describe "Time#+" do
 
   it "preserves time zone" do
     time_with_zone = Time.now.utc
-    time_with_zone.zone.should == (time_with_zone + 60*60).zone
+    time_with_zone.zone.should == (time_with_zone + 1).zone
 
     time_with_zone = Time.now
-    time_with_zone.zone.should == (time_with_zone + 60*60).zone
+    time_with_zone.zone.should == (time_with_zone + 1).zone
   end
 
-  ruby_version_is "2.6" do
-    context "zone is a timezone object" do
-      it "preserves time zone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2012, 1, 1, 12, 0, 0, zone) + 60*60
+  context "zone is a timezone object" do
+    it "preserves time zone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.new(2012, 1, 1, 12, 0, 0, zone) + 1
 
-        time.zone.should == zone
-      end
+      time.zone.should == zone
     end
   end
 
   it "does not return a subclass instance" do
     c = Class.new(Time)
     x = c.now + 1
-    x.should be_an_instance_of(Time)
+    x.should.instance_of?(Time)
   end
 
   it "raises TypeError on Time argument" do
-    -> { Time.now + Time.now }.should raise_error(TypeError)
+    -> { Time.now + Time.now }.should.raise(TypeError)
   end
 
   it "raises TypeError on nil argument" do
-    -> { Time.now + nil }.should raise_error(TypeError)
+    -> { Time.now + nil }.should.raise(TypeError)
   end
 
   #see [ruby-dev:38446]
diff --git a/spec/ruby/core/time/round_spec.rb b/spec/ruby/core/time/round_spec.rb
index 0cbed04ade..a739cabfdf 100644
--- a/spec/ruby/core/time/round_spec.rb
+++ b/spec/ruby/core/time/round_spec.rb
@@ -20,8 +20,8 @@ describe "Time#round" do
   it "returns an instance of Time, even if #round is called on a subclass" do
     subclass = Class.new(Time)
     instance = subclass.at(0)
-    instance.class.should equal subclass
-    instance.round.should be_an_instance_of(Time)
+    instance.class.should.equal? subclass
+    instance.round.should.instance_of?(Time)
   end
 
   it "copies own timezone to the returning value" do
diff --git a/spec/ruby/core/time/saturday_spec.rb b/spec/ruby/core/time/saturday_spec.rb
index 60ffea4198..0e51407366 100644
--- a/spec/ruby/core/time/saturday_spec.rb
+++ b/spec/ruby/core/time/saturday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#saturday?" do
   it "returns true if time represents Saturday" do
-    Time.local(2000, 1, 1).saturday?.should == true
+    Time.local(2000, 1, 1).should.saturday?
   end
 
   it "returns false if time doesn't represent Saturday" do
-    Time.local(2000, 1, 2).saturday?.should == false
+    Time.local(2000, 1, 2).should_not.saturday?
   end
 end
diff --git a/spec/ruby/core/time/shared/gmtime.rb b/spec/ruby/core/time/shared/gmtime.rb
index 5ed64c2ab6..aa76b436cc 100644
--- a/spec/ruby/core/time/shared/gmtime.rb
+++ b/spec/ruby/core/time/shared/gmtime.rb
@@ -4,14 +4,21 @@ describe :time_gmtime, shared: true do
     with_timezone("CST", -6) do
       t = Time.local(2007, 1, 9, 6, 0, 0)
       t.send(@method)
-      t.should == Time.gm(2007, 1, 9, 12, 0, 0)
+      # Time#== compensates for time zones, so check all parts separately
+      t.year.should == 2007
+      t.month.should == 1
+      t.mday.should == 9
+      t.hour.should == 12
+      t.min.should == 0
+      t.sec.should == 0
+      t.zone.should == "UTC"
     end
   end
 
   it "returns self" do
     with_timezone("CST", -6) do
       t = Time.local(2007, 1, 9, 12, 0, 0)
-      t.send(@method).should equal(t)
+      t.send(@method).should.equal?(t)
     end
   end
 
@@ -19,14 +26,14 @@ describe :time_gmtime, shared: true do
     it "does not raise an error if already in UTC" do
       time = Time.gm(2007, 1, 9, 12, 0, 0)
       time.freeze
-      time.send(@method).should equal(time)
+      time.send(@method).should.equal?(time)
     end
 
-    it "raises a RuntimeError if the time is not UTC" do
+    it "raises a FrozenError if the time is not UTC" do
       with_timezone("CST", -6) do
         time = Time.now
         time.freeze
-        -> { time.send(@method) }.should raise_error(RuntimeError)
+        -> { time.send(@method) }.should.raise(FrozenError)
       end
     end
   end
diff --git a/spec/ruby/core/time/shared/inspect.rb b/spec/ruby/core/time/shared/inspect.rb
index 4133671924..82f7f3c686 100644
--- a/spec/ruby/core/time/shared/inspect.rb
+++ b/spec/ruby/core/time/shared/inspect.rb
@@ -16,6 +16,6 @@ describe :inspect, shared: true do
   end
 
   it "returns a US-ASCII encoded string" do
-    Time.now.send(@method).encoding.should equal(Encoding::US_ASCII)
+    Time.now.send(@method).encoding.should.equal?(Encoding::US_ASCII)
   end
 end
diff --git a/spec/ruby/core/time/shared/local.rb b/spec/ruby/core/time/shared/local.rb
index 43f331c4c1..068e314999 100644
--- a/spec/ruby/core/time/shared/local.rb
+++ b/spec/ruby/core/time/shared/local.rb
@@ -7,12 +7,10 @@ describe :time_local, shared: true do
   end
 
   platform_is_not :windows do
-    describe "timezone changes" do
-      it "correctly adjusts the timezone change to 'CEST' on 'Europe/Amsterdam'" do
-        with_timezone("Europe/Amsterdam") do
-          Time.send(@method, 1940, 5, 16).to_a.should ==
-            [0, 40, 1, 16, 5, 1940, 4, 137, true, "CEST"]
-        end
+    it "uses the 'CET' timezone with TZ=Europe/Amsterdam in 1970" do
+      with_timezone("Europe/Amsterdam") do
+        Time.send(@method, 1970, 5, 16).to_a.should ==
+          [0, 0, 0, 16, 5, 1970, 6, 136, false, "CET"]
       end
     end
   end
@@ -41,5 +39,4 @@ describe :time_local_10_arg, shared: true do
       end
     end
   end
-
 end
diff --git a/spec/ruby/core/time/shared/now.rb b/spec/ruby/core/time/shared/now.rb
index d8e5ac9d50..839cfdcd2a 100644
--- a/spec/ruby/core/time/shared/now.rb
+++ b/spec/ruby/core/time/shared/now.rb
@@ -2,8 +2,8 @@ require_relative '../fixtures/classes'
 
 describe :time_now, shared: true do
   it "creates a subclass instance if called on a subclass" do
-    TimeSpecs::SubTime.send(@method).should be_an_instance_of(TimeSpecs::SubTime)
-    TimeSpecs::MethodHolder.send(@method).should be_an_instance_of(Time)
+    TimeSpecs::SubTime.send(@method).should.instance_of?(TimeSpecs::SubTime)
+    TimeSpecs::MethodHolder.send(@method).should.instance_of?(Time)
   end
 
   it "sets the current time" do
@@ -18,18 +18,16 @@ describe :time_now, shared: true do
     end
   end
 
-  guard_not -> { platform_is :windows and ruby_version_is ""..."2.5" } do
-    it "has at least microsecond precision" do
-      times = []
-      10_000.times do
-        times << Time.now.nsec
-      end
-
-      # The clock should not be less accurate than expected (times should
-      # not all be a multiple of the next precision up, assuming precisions
-      # are multiples of ten.)
-      expected = 1_000
-      times.select { |t| t % (expected * 10) == 0  }.size.should_not == times.size
+  it "has at least microsecond precision" do
+    # The clock should not be less accurate than expected (times should
+    # not all be a multiple of the next precision up, assuming precisions
+    # are multiples of ten.)
+    expected = 1_000
+    t = 0
+    10_000.times.find do
+      t = Time.now.nsec
+      t % (expected * 10) != 0
     end
+    (t % (expected * 10)).should != 0
   end
 end
diff --git a/spec/ruby/core/time/shared/time_params.rb b/spec/ruby/core/time/shared/time_params.rb
index 63d0dbc120..f0de986b8e 100644
--- a/spec/ruby/core/time/shared/time_params.rb
+++ b/spec/ruby/core/time/shared/time_params.rb
@@ -30,7 +30,7 @@ describe :time_params, shared: true do
   end
 
   it "raises a TypeError if the year is nil" do
-    -> { Time.send(@method, nil) }.should raise_error(TypeError)
+    -> { Time.send(@method, nil) }.should.raise(TypeError)
   end
 
   it "accepts nil month, day, hour, minute, and second" do
@@ -145,46 +145,55 @@ describe :time_params, shared: true do
   end
 
   it "raises an ArgumentError for out of range month" do
+    # For some reason MRI uses a different message for month in 13-15 and month>=16
     -> {
-      Time.send(@method, 2008, 13, 31, 23, 59, 59)
-    }.should raise_error(ArgumentError)
+      Time.send(@method, 2008, 16, 31, 23, 59, 59)
+    }.should.raise(ArgumentError, /(mon|argument) out of range/)
   end
 
   it "raises an ArgumentError for out of range day" do
     -> {
       Time.send(@method, 2008, 12, 32, 23, 59, 59)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for out of range hour" do
     -> {
       Time.send(@method, 2008, 12, 31, 25, 59, 59)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for out of range minute" do
     -> {
       Time.send(@method, 2008, 12, 31, 23, 61, 59)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an ArgumentError for out of range second" do
+    # For some reason MRI uses different messages for seconds 61-63 and seconds >= 64
     -> {
       Time.send(@method, 2008, 12, 31, 23, 59, 61)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError, /(sec|argument) out of range/)
+    -> {
+      Time.send(@method, 2008, 12, 31, 23, 59, -1)
+    }.should.raise(ArgumentError, "argument out of range")
+  end
+
+  it "raises ArgumentError when given 8 arguments" do
+    -> { Time.send(@method, *[0]*8) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError when given 9 arguments" do
-    -> { Time.send(@method, *[0]*9) }.should raise_error(ArgumentError)
+    -> { Time.send(@method, *[0]*9) }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError when given 11 arguments" do
-    -> { Time.send(@method, *[0]*11) }.should raise_error(ArgumentError)
+    -> { Time.send(@method, *[0]*11) }.should.raise(ArgumentError)
   end
 
   it "returns subclass instances" do
     c = Class.new(Time)
-    c.send(@method, 2008, "12").should be_an_instance_of(c)
+    c.send(@method, 2008, "12").should.instance_of?(c)
   end
 end
 
@@ -204,23 +213,23 @@ describe :time_params_10_arg, shared: true do
   it "raises an ArgumentError for out of range values" do
     -> {
       Time.send(@method, 61, 59, 23, 31, 12, 2008, :ignored, :ignored, :ignored, :ignored)
-    }.should raise_error(ArgumentError) # sec
+    }.should.raise(ArgumentError) # sec
 
     -> {
       Time.send(@method, 59, 61, 23, 31, 12, 2008, :ignored, :ignored, :ignored, :ignored)
-    }.should raise_error(ArgumentError) # min
+    }.should.raise(ArgumentError) # min
 
     -> {
       Time.send(@method, 59, 59, 25, 31, 12, 2008, :ignored, :ignored, :ignored, :ignored)
-    }.should raise_error(ArgumentError) # hour
+    }.should.raise(ArgumentError) # hour
 
     -> {
       Time.send(@method, 59, 59, 23, 32, 12, 2008, :ignored, :ignored, :ignored, :ignored)
-    }.should raise_error(ArgumentError) # day
+    }.should.raise(ArgumentError) # day
 
     -> {
       Time.send(@method, 59, 59, 23, 31, 13, 2008, :ignored, :ignored, :ignored, :ignored)
-    }.should raise_error(ArgumentError) # month
+    }.should.raise(ArgumentError) # month
   end
 end
 
@@ -231,7 +240,7 @@ describe :time_params_microseconds, shared: true do
   end
 
   it "raises an ArgumentError for out of range microsecond" do
-    -> { Time.send(@method, 2000, 1, 1, 20, 15, 1, 1000000) }.should raise_error(ArgumentError)
+    -> { Time.send(@method, 2000, 1, 1, 20, 15, 1, 1000000) }.should.raise(ArgumentError)
   end
 
   it "handles fractional microseconds as a Float" do
diff --git a/spec/ruby/core/time/shared/to_i.rb b/spec/ruby/core/time/shared/to_i.rb
index 03497c700b..06c966b708 100644
--- a/spec/ruby/core/time/shared/to_i.rb
+++ b/spec/ruby/core/time/shared/to_i.rb
@@ -6,4 +6,11 @@ describe :time_to_i, shared: true do
   it "doesn't return an actual number of seconds in time" do
     Time.at(65.5).send(@method).should == 65
   end
+
+  it "rounds fractional seconds toward zero" do
+    t = Time.utc(1960, 1, 1, 0, 0, 0, 999_999)
+
+    t.to_f.to_i.should == -315619199
+    t.to_i.should == -315619200
+  end
 end
diff --git a/spec/ruby/core/time/shared/xmlschema.rb b/spec/ruby/core/time/shared/xmlschema.rb
new file mode 100644
index 0000000000..d68c18df36
--- /dev/null
+++ b/spec/ruby/core/time/shared/xmlschema.rb
@@ -0,0 +1,31 @@
+describe :time_xmlschema, shared: true do
+  ruby_version_is "3.4" do
+    it "generates ISO-8601 strings in Z for UTC times" do
+      t = Time.utc(1985, 4, 12, 23, 20, 50, 521245)
+      t.send(@method).should == "1985-04-12T23:20:50Z"
+      t.send(@method, 2).should == "1985-04-12T23:20:50.52Z"
+      t.send(@method, 9).should == "1985-04-12T23:20:50.521245000Z"
+    end
+
+    it "generates ISO-8601 string with timeone offset for non-UTC times" do
+      t = Time.new(1985, 4, 12, 23, 20, 50, "+02:00")
+      t.send(@method).should == "1985-04-12T23:20:50+02:00"
+      t.send(@method, 2).should == "1985-04-12T23:20:50.00+02:00"
+    end
+
+    it "year is always at least 4 digits" do
+      t = Time.utc(12, 4, 12)
+      t.send(@method).should ==  "0012-04-12T00:00:00Z"
+    end
+
+    it "year can be more than 4 digits" do
+      t = Time.utc(40_000, 4, 12)
+      t.send(@method).should ==  "40000-04-12T00:00:00Z"
+    end
+
+    it "year can be negative" do
+      t = Time.utc(-2000, 4, 12)
+      t.send(@method).should ==  "-2000-04-12T00:00:00Z"
+    end
+  end
+end
diff --git a/spec/ruby/core/time/strftime_spec.rb b/spec/ruby/core/time/strftime_spec.rb
index 1bd24b0538..1528a668a1 100644
--- a/spec/ruby/core/time/strftime_spec.rb
+++ b/spec/ruby/core/time/strftime_spec.rb
@@ -25,7 +25,7 @@ describe "Time#strftime" do
 
   # Differences with date
   it "requires an argument" do
-    -> { @time.strftime }.should raise_error(ArgumentError)
+    -> { @time.strftime }.should.raise(ArgumentError)
   end
 
   # %Z is zone name or empty for Time
@@ -49,4 +49,43 @@ describe "Time#strftime" do
     time = @new_time_with_offset[2012, 1, 1, 0, 0, 0, Rational(36645, 10)]
     time.strftime("%::z").should == "+01:01:05"
   end
+
+  it "supports RFC 3339 UTC for unknown offset local time, -0000, as %-z" do
+    time = Time.gm(2022)
+
+    time.strftime("%z").should == "+0000"
+    time.strftime("%-z").should == "-0000"
+    time.strftime("%-:z").should == "-00:00"
+    time.strftime("%-::z").should == "-00:00:00"
+  end
+
+  it "applies '-' flag to UTC time" do
+    time = Time.utc(2022)
+    time.strftime("%-z").should == "-0000"
+
+    time = Time.gm(2022)
+    time.strftime("%-z").should == "-0000"
+
+    time = Time.new(2022, 1, 1, 0, 0, 0, "Z")
+    time.strftime("%-z").should == "-0000"
+
+    time = Time.new(2022, 1, 1, 0, 0, 0, "-00:00")
+    time.strftime("%-z").should == "-0000"
+
+    time = Time.new(2022, 1, 1, 0, 0, 0, "+03:00").utc
+    time.strftime("%-z").should == "-0000"
+  end
+
+  it "ignores '-' flag for non-UTC time" do
+    time = Time.new(2022, 1, 1, 0, 0, 0, "+03:00")
+    time.strftime("%-z").should == "+0300"
+  end
+
+  it "works correctly with width, _ and 0 flags, and :" do
+    Time.now.utc.strftime("%-_10z").should == "      -000"
+    Time.now.utc.strftime("%-10z").should == "-000000000"
+    Time.now.utc.strftime("%-010:z").should == "-000000:00"
+    Time.now.utc.strftime("%-_10:z").should == "     -0:00"
+    Time.now.utc.strftime("%-_10::z").should == "  -0:00:00"
+  end
 end
diff --git a/spec/ruby/core/time/subsec_spec.rb b/spec/ruby/core/time/subsec_spec.rb
index 583a26412b..3ed1bf5dd1 100644
--- a/spec/ruby/core/time/subsec_spec.rb
+++ b/spec/ruby/core/time/subsec_spec.rb
@@ -1,27 +1,27 @@
 require_relative '../../spec_helper'
 
 describe "Time#subsec" do
-  it "returns 0 as a Fixnum for a Time with a whole number of seconds" do
-    Time.at(100).subsec.should eql(0)
+  it "returns 0 as an Integer for a Time with a whole number of seconds" do
+    Time.at(100).subsec.should.eql?(0)
   end
 
   it "returns the fractional seconds as a Rational for a Time constructed with a Rational number of seconds" do
-    Time.at(Rational(3, 2)).subsec.should eql(Rational(1, 2))
+    Time.at(Rational(3, 2)).subsec.should.eql?(Rational(1, 2))
   end
 
   it "returns the fractional seconds as a Rational for a Time constructed with a Float number of seconds" do
-    Time.at(10.75).subsec.should eql(Rational(3, 4))
+    Time.at(10.75).subsec.should.eql?(Rational(3, 4))
   end
 
   it "returns the fractional seconds as a Rational for a Time constructed with an Integer number of microseconds" do
-    Time.at(0, 999999).subsec.should eql(Rational(999999, 1000000))
+    Time.at(0, 999999).subsec.should.eql?(Rational(999999, 1000000))
   end
 
   it "returns the fractional seconds as a Rational for a Time constructed with an Rational number of microseconds" do
-    Time.at(0, Rational(9, 10)).subsec.should eql(Rational(9, 10000000))
+    Time.at(0, Rational(9, 10)).subsec.should.eql?(Rational(9, 10000000))
   end
 
   it "returns the fractional seconds as a Rational for a Time constructed with an Float number of microseconds" do
-    Time.at(0, 0.75).subsec.should eql(Rational(3, 4000000))
+    Time.at(0, 0.75).subsec.should.eql?(Rational(3, 4000000))
   end
 end
diff --git a/spec/ruby/core/time/succ_spec.rb b/spec/ruby/core/time/succ_spec.rb
deleted file mode 100644
index e68e64b0cc..0000000000
--- a/spec/ruby/core/time/succ_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
-
-describe "Time#succ" do
-  it "returns a new time one second later than time" do
-    suppress_warning {
-      @result = Time.at(100).succ
-    }
-
-    @result.should == Time.at(101)
-  end
-
-  it "returns a new instance" do
-    time = Time.at(100)
-
-    suppress_warning {
-      @result = time.succ
-    }
-
-    @result.should_not equal time
-  end
-
-  it "is obsolete" do
-    -> {
-      Time.at(100).succ
-    }.should complain(/Time#succ is obsolete/)
-  end
-
-  ruby_version_is "2.6" do
-    context "zone is a timezone object" do
-      it "preserves time zone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 60*60
-
-        time.zone.should == zone
-      end
-    end
-  end
-end
diff --git a/spec/ruby/core/time/sunday_spec.rb b/spec/ruby/core/time/sunday_spec.rb
index 2285583579..0d46421132 100644
--- a/spec/ruby/core/time/sunday_spec.rb
+++ b/spec/ruby/core/time/sunday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#sunday?" do
   it "returns true if time represents Sunday" do
-    Time.local(2000, 1, 2).sunday?.should == true
+    Time.local(2000, 1, 2).should.sunday?
   end
 
   it "returns false if time doesn't represent Sunday" do
-    Time.local(2000, 1, 1).sunday?.should == false
+    Time.local(2000, 1, 1).should_not.sunday?
   end
 end
diff --git a/spec/ruby/core/time/thursday_spec.rb b/spec/ruby/core/time/thursday_spec.rb
index c82d517519..c11e79d2fa 100644
--- a/spec/ruby/core/time/thursday_spec.rb
+++ b/spec/ruby/core/time/thursday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#thursday?" do
   it "returns true if time represents Thursday" do
-    Time.local(2000, 1, 6).thursday?.should == true
+    Time.local(2000, 1, 6).should.thursday?
   end
 
   it "returns false if time doesn't represent Thursday" do
-    Time.local(2000, 1, 1).thursday?.should == false
+    Time.local(2000, 1, 1).should_not.thursday?
   end
 end
diff --git a/spec/ruby/core/time/to_r_spec.rb b/spec/ruby/core/time/to_r_spec.rb
index 6af2d9b7ea..e30f5d8f94 100644
--- a/spec/ruby/core/time/to_r_spec.rb
+++ b/spec/ruby/core/time/to_r_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#to_r" do
   it "returns the a Rational representing seconds and subseconds since the epoch" do
-    Time.at(Rational(11, 10)).to_r.should eql(Rational(11, 10))
+    Time.at(Rational(11, 10)).to_r.should.eql?(Rational(11, 10))
   end
 
   it "returns a Rational even for a whole number of seconds" do
-    Time.at(2).to_r.should eql(Rational(2))
+    Time.at(2).to_r.should.eql?(Rational(2))
   end
 end
diff --git a/spec/ruby/core/time/tuesday_spec.rb b/spec/ruby/core/time/tuesday_spec.rb
index 7abbdc92c0..0e7b9e7506 100644
--- a/spec/ruby/core/time/tuesday_spec.rb
+++ b/spec/ruby/core/time/tuesday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#tuesday?" do
   it "returns true if time represents Tuesday" do
-    Time.local(2000, 1, 4).tuesday?.should == true
+    Time.local(2000, 1, 4).should.tuesday?
   end
 
   it "returns false if time doesn't represent Tuesday" do
-    Time.local(2000, 1, 1).tuesday?.should == false
+    Time.local(2000, 1, 1).should_not.tuesday?
   end
 end
diff --git a/spec/ruby/core/time/utc_spec.rb b/spec/ruby/core/time/utc_spec.rb
index 5074c8d54d..ab3c0df657 100644
--- a/spec/ruby/core/time/utc_spec.rb
+++ b/spec/ruby/core/time/utc_spec.rb
@@ -4,8 +4,53 @@ require_relative 'shared/gmtime'
 require_relative 'shared/time_params'
 
 describe "Time#utc?" do
-  it "returns true if time represents a time in UTC (GMT)" do
+  it "returns true only if time represents a time in UTC (GMT)" do
     Time.now.utc?.should == false
+    Time.now.utc.utc?.should == true
+  end
+
+  it "treats time as UTC what was created in different ways" do
+    Time.now.utc.utc?.should == true
+    Time.now.gmtime.utc?.should == true
+    Time.now.getgm.utc?.should == true
+    Time.now.getutc.utc?.should == true
+    Time.utc(2022).utc?.should == true
+  end
+
+  it "does treat time with 'UTC' offset as UTC" do
+    Time.new(2022, 1, 1, 0, 0, 0, "UTC").utc?.should == true
+    Time.now.localtime("UTC").utc?.should == true
+    Time.at(Time.now, in: 'UTC').utc?.should == true
+
+    Time.new(2022, 1, 1, 0, 0, 0, in: "UTC").utc?.should == true
+    Time.now(in: "UTC").utc?.should == true
+  end
+
+  it "does treat time with Z offset as UTC" do
+    Time.new(2022, 1, 1, 0, 0, 0, "Z").utc?.should == true
+    Time.now.localtime("Z").utc?.should == true
+    Time.at(Time.now, in: 'Z').utc?.should == true
+
+    Time.new(2022, 1, 1, 0, 0, 0, in: "Z").utc?.should == true
+    Time.now(in: "Z").utc?.should == true
+  end
+
+  it "does treat time with -00:00 offset as UTC" do
+    Time.new(2022, 1, 1, 0, 0, 0, "-00:00").utc?.should == true
+    Time.now.localtime("-00:00").utc?.should == true
+    Time.at(Time.now, in: '-00:00').utc?.should == true
+  end
+
+  it "does not treat time with +00:00 offset as UTC" do
+    Time.new(2022, 1, 1, 0, 0, 0, "+00:00").utc?.should == false
+    Time.now.localtime("+00:00").utc?.should == false
+    Time.at(Time.now, in: "+00:00").utc?.should == false
+  end
+
+  it "does not treat time with 0 offset as UTC" do
+    Time.new(2022, 1, 1, 0, 0, 0, 0).utc?.should == false
+    Time.now.localtime(0).utc?.should == false
+    Time.at(Time.now, in: 0).utc?.should == false
   end
 end
 
diff --git a/spec/ruby/core/time/wednesday_spec.rb b/spec/ruby/core/time/wednesday_spec.rb
index 6a52c3577b..cc686681d7 100644
--- a/spec/ruby/core/time/wednesday_spec.rb
+++ b/spec/ruby/core/time/wednesday_spec.rb
@@ -2,10 +2,10 @@ require_relative '../../spec_helper'
 
 describe "Time#wednesday?" do
   it "returns true if time represents Wednesday" do
-    Time.local(2000, 1, 5).wednesday?.should == true
+    Time.local(2000, 1, 5).should.wednesday?
   end
 
   it "returns false if time doesn't represent Wednesday" do
-    Time.local(2000, 1, 1).wednesday?.should == false
+    Time.local(2000, 1, 1).should_not.wednesday?
   end
 end
diff --git a/spec/ruby/core/time/xmlschema_spec.rb b/spec/ruby/core/time/xmlschema_spec.rb
new file mode 100644
index 0000000000..bdf1dc7923
--- /dev/null
+++ b/spec/ruby/core/time/xmlschema_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/xmlschema'
+
+describe "Time#xmlschema" do
+  it_behaves_like :time_xmlschema, :xmlschema
+end
diff --git a/spec/ruby/core/time/yday_spec.rb b/spec/ruby/core/time/yday_spec.rb
index 6ea5ff8f1b..e920c2e28d 100644
--- a/spec/ruby/core/time/yday_spec.rb
+++ b/spec/ruby/core/time/yday_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative '../../shared/time/yday'
 
 describe "Time#yday" do
   it "returns an integer representing the day of the year, 1..366" do
@@ -7,15 +8,5 @@ describe "Time#yday" do
     end
   end
 
-  it 'returns the correct value for each day of each month' do
-    mdays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
-
-    yday = 1
-    mdays.each_with_index do |days, month|
-      days.times do |day|
-        Time.new(2014, month+1, day+1).yday.should == yday
-        yday += 1
-      end
-    end
-  end
+  it_behaves_like :time_yday, -> year, month, day { Time.new(year, month, day).yday }
 end
diff --git a/spec/ruby/core/time/zone_spec.rb b/spec/ruby/core/time/zone_spec.rb
index 907ccf9f4b..2cb3c5e7bb 100644
--- a/spec/ruby/core/time/zone_spec.rb
+++ b/spec/ruby/core/time/zone_spec.rb
@@ -6,7 +6,7 @@ describe "Time#zone" do
       with_timezone("America/New_York") do
         Time.new(2001, 1, 1, 0, 0, 0).zone.should == "EST"
         Time.new(2001, 7, 1, 0, 0, 0).zone.should == "EDT"
-        %w[EST EDT].should include Time.now.zone
+        %w[EST EDT].should.include? Time.now.zone
       end
     end
   end
@@ -29,7 +29,7 @@ describe "Time#zone" do
     t = Time.new(2005, 2, 27, 22, 50, 0, -3600)
 
     with_timezone("America/New_York") do
-      t.getlocal("+05:00").zone.should be_nil
+      t.getlocal("+05:00").zone.should == nil
     end
   end
 
@@ -52,14 +52,35 @@ describe "Time#zone" do
     end
 
     it "doesn't raise errors for a Time with a fixed offset" do
-      -> {
-        Time.new(2001, 1, 1, 0, 0, 0, "+05:00").zone
-      }.should_not raise_error
+      Time.new(2001, 1, 1, 0, 0, 0, "+05:00").zone.should == nil
     end
   end
 
   it "returns UTC when called on a UTC time" do
     Time.now.utc.zone.should == "UTC"
+    Time.now.gmtime.zone.should == "UTC"
+    Time.now.getgm.zone.should == "UTC"
+    Time.now.getutc.zone.should == "UTC"
+    Time.utc(2022).zone.should == "UTC"
+    Time.new(2022, 1, 1, 0, 0, 0, "UTC").zone.should == "UTC"
+    Time.new(2022, 1, 1, 0, 0, 0, "Z").zone.should == "UTC"
+    Time.now.localtime("UTC").zone.should == "UTC"
+    Time.now.localtime("Z").zone.should == "UTC"
+    Time.at(Time.now, in: 'UTC').zone.should == "UTC"
+    Time.at(Time.now, in: 'Z').zone.should == "UTC"
+
+    Time.new(2022, 1, 1, 0, 0, 0, "-00:00").zone.should == "UTC"
+    Time.now.localtime("-00:00").zone.should == "UTC"
+    Time.at(Time.now, in: '-00:00').zone.should == "UTC"
+
+    Time.new(2022, 1, 1, 0, 0, 0, in: "UTC").zone.should == "UTC"
+    Time.new(2022, 1, 1, 0, 0, 0, in: "Z").zone.should == "UTC"
+
+    Time.now(in: 'UTC').zone.should == "UTC"
+    Time.now(in: 'Z').zone.should == "UTC"
+
+    Time.at(Time.now, in: 'UTC').zone.should == "UTC"
+    Time.at(Time.now, in: 'Z').zone.should == "UTC"
   end
 
   platform_is_not :aix, :windows do
diff --git a/spec/ruby/core/tracepoint/allow_reentry_spec.rb b/spec/ruby/core/tracepoint/allow_reentry_spec.rb
new file mode 100644
index 0000000000..475cca29a9
--- /dev/null
+++ b/spec/ruby/core/tracepoint/allow_reentry_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe 'TracePoint.allow_reentry' do
+  it 'allows the reentrance in a given block' do
+    event_lines = []
+    l1 = l2 = l3 = l4 = nil
+    TracePoint.new(:line) do |tp|
+      next unless TracePointSpec.target_thread?
+
+      event_lines << tp.lineno
+      next if (__LINE__ + 2 .. __LINE__ + 4).cover?(tp.lineno)
+      TracePoint.allow_reentry do
+        a = 1; l3 = __LINE__
+        b = 2; l4 = __LINE__
+      end
+    end.enable do
+      c = 3; l1 = __LINE__
+      d = 4; l2 = __LINE__
+    end
+
+    event_lines.should == [l1, l3, l4, l2, l3, l4]
+  end
+
+  it 'raises RuntimeError when not called inside a TracePoint' do
+    -> {
+      TracePoint.allow_reentry{}
+    }.should.raise(RuntimeError)
+  end
+end
diff --git a/spec/ruby/core/tracepoint/binding_spec.rb b/spec/ruby/core/tracepoint/binding_spec.rb
index f37753602e..6de6e47d7d 100644
--- a/spec/ruby/core/tracepoint/binding_spec.rb
+++ b/spec/ruby/core/tracepoint/binding_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#binding' do
   def test
@@ -8,12 +9,13 @@ describe 'TracePoint#binding' do
   it 'return the generated binding object from event' do
     bindings = []
     TracePoint.new(:return) { |tp|
+      next unless TracePointSpec.target_thread?
       bindings << tp.binding
     }.enable {
       test
     }
     bindings.size.should == 1
-    bindings[0].should be_kind_of(Binding)
+    bindings[0].should.is_a?(Binding)
     bindings[0].local_variables.should == [:secret]
   end
 end
diff --git a/spec/ruby/core/tracepoint/callee_id_spec.rb b/spec/ruby/core/tracepoint/callee_id_spec.rb
index d340290d8b..cc08a45504 100644
--- a/spec/ruby/core/tracepoint/callee_id_spec.rb
+++ b/spec/ruby/core/tracepoint/callee_id_spec.rb
@@ -7,6 +7,7 @@ describe "TracePoint#callee_id" do
     obj = TracePointSpec::ClassWithMethodAlias.new
 
     TracePoint.new(:call) do |tp|
+      next unless TracePointSpec.target_thread?
       a << tp.callee_id
     end.enable do
       obj.m_alias
diff --git a/spec/ruby/core/tracepoint/defined_class_spec.rb b/spec/ruby/core/tracepoint/defined_class_spec.rb
index 72536e6a56..53c86a8210 100644
--- a/spec/ruby/core/tracepoint/defined_class_spec.rb
+++ b/spec/ruby/core/tracepoint/defined_class_spec.rb
@@ -5,22 +5,23 @@ describe 'TracePoint#defined_class' do
   it 'returns class or module of the method being called' do
     last_class_name = nil
     TracePoint.new(:call) do |tp|
+      next unless TracePointSpec.target_thread?
       last_class_name = tp.defined_class
     end.enable do
       TracePointSpec::B.new.foo
-      last_class_name.should equal(TracePointSpec::B)
+      last_class_name.should.equal?(TracePointSpec::B)
 
       TracePointSpec::B.new.bar
-      last_class_name.should equal(TracePointSpec::A)
+      last_class_name.should.equal?(TracePointSpec::A)
 
       c = TracePointSpec::C.new
-      last_class_name.should equal(TracePointSpec::C)
+      last_class_name.should.equal?(TracePointSpec::C)
 
       c.foo
-      last_class_name.should equal(TracePointSpec::B)
+      last_class_name.should.equal?(TracePointSpec::B)
 
       c.bar
-      last_class_name.should equal(TracePointSpec::A)
+      last_class_name.should.equal?(TracePointSpec::A)
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/disable_spec.rb b/spec/ruby/core/tracepoint/disable_spec.rb
index 612ca3c25a..73a31b3b81 100644
--- a/spec/ruby/core/tracepoint/disable_spec.rb
+++ b/spec/ruby/core/tracepoint/disable_spec.rb
@@ -1,9 +1,11 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#disable' do
   it 'returns true if trace was enabled' do
     called = false
     trace = TracePoint.new(:line) do |tp|
+      next unless TracePointSpec.target_thread?
       called = true
     end
 
@@ -25,6 +27,7 @@ describe 'TracePoint#disable' do
   it 'returns false if trace was disabled' do
     called = false
     trace = TracePoint.new(:line) do |tp|
+      next unless TracePointSpec.target_thread?
       called = true
     end
 
@@ -41,7 +44,7 @@ describe 'TracePoint#disable' do
     begin
       trace.disable { enabled = trace.enabled? }
       enabled.should == false
-      trace.enabled?.should == true
+      trace.should.enabled?
     ensure
       trace.disable
     end
@@ -52,7 +55,7 @@ describe 'TracePoint#disable' do
     trace.enable
     begin
       trace.disable { 42 }.should == 42
-      trace.enabled?.should == true
+      trace.should.enabled?
     ensure
       trace.disable
     end
@@ -65,7 +68,7 @@ describe 'TracePoint#disable' do
       trace.disable do |*args|
         args.should == []
       end
-      trace.enabled?.should == true
+      trace.should.enabled?
     ensure
       trace.disable
     end
diff --git a/spec/ruby/core/tracepoint/enable_spec.rb b/spec/ruby/core/tracepoint/enable_spec.rb
index b0fe38c559..bf61c35154 100644
--- a/spec/ruby/core/tracepoint/enable_spec.rb
+++ b/spec/ruby/core/tracepoint/enable_spec.rb
@@ -1,20 +1,21 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#enable' do
-  # def test; end
-
   describe 'without a block' do
-    it 'returns true if trace was enabled' do
+    it 'returns false if trace was disabled' do
       called = false
       trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
         called = true
       end
 
       line_event = true
       called.should == false
 
-      trace.enable
+      ret = trace.enable
       begin
+        ret.should == false
         line_event = true
         called.should == true
       ensure
@@ -22,30 +23,27 @@ describe 'TracePoint#enable' do
       end
     end
 
-    it 'returns false if trace was disabled' do
+    it 'returns true if trace was already enabled' do
       called = false
       trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
         called = true
       end
 
-      trace.enable.should == false
-      begin
-        line_event = true
-        called.should == true
-      ensure
-        trace.disable
-      end
-
-      called = false
       line_event = true
       called.should == false
 
-      trace.enable.should == false
+      ret = trace.enable
       begin
+        ret.should == false
+
+        trace.enable.should == true
+
         line_event = true
         called.should == true
       ensure
         trace.disable
+        trace.should_not.enabled?
       end
     end
   end
@@ -54,18 +52,43 @@ describe 'TracePoint#enable' do
     it 'enables the trace object within a block' do
       event_name = nil
       TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
         event_name = tp.event
-      end.enable { event_name.should equal(:line) }
+      end.enable { event_name.should.equal?(:line) }
+    end
+
+    it 'enables the trace object only for the current thread' do
+      threads = []
+      trace = TracePoint.new(:line) do |tp|
+        # Runs on purpose on any Thread
+        threads << Thread.current
+      end
+
+      thread = nil
+      trace.enable do
+        line_event = true
+        thread = Thread.new do
+          event_in_other_thread = true
+        end
+        thread.join
+      end
+
+      threads = threads.uniq
+      threads.should.include?(Thread.current)
+      threads.should_not.include?(thread)
     end
 
     it 'can accept arguments within a block but it should not yield arguments' do
       event_name = nil
-      trace = TracePoint.new(:line) { |tp| event_name = tp.event }
+      trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        event_name = tp.event
+      end
       trace.enable do |*args|
-        event_name.should equal(:line)
+        event_name.should.equal?(:line)
         args.should == []
       end
-      trace.enabled?.should == false
+      trace.should_not.enabled?
     end
 
     it 'enables trace object on calling with a block if it was already enabled' do
@@ -87,394 +110,434 @@ describe 'TracePoint#enable' do
 
     it 'disables the trace object outside the block' do
       called = false
-      trace = TracePoint.new(:line) { called = true }
+      trace = TracePoint.new(:line) do
+        next unless TracePointSpec.target_thread?
+        called = true
+      end
       trace.enable {
         line_event = true
       }
       called.should == true
-      trace.enabled?.should == false
+      trace.should_not.enabled?
     end
   end
 
-  ruby_version_is "2.6" do
-    describe 'target: option' do
-      before :each do
-        ScratchPad.record []
+  describe "when nested" do
+    before do
+      @path_prefix = ' '
+    end
+
+    it "enables both TracePoints but only calls the respective callbacks" do
+      called = false
+      first = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        called = true
       end
 
-      it 'enables trace point for specific location' do
-        trace = TracePoint.new(:call) do |tp|
-          ScratchPad << tp.method_id
+      all = []
+      inspects = []
+      second = TracePoint.new(:line) { |tp|
+        next unless TracePointSpec.target_thread?
+        all << tp
+        inspects << tp.inspect
+      }
+
+      line = nil
+      first.enable do
+        second.enable do
+          line = __LINE__
         end
+      end
 
-        obj = Object.new
-        def obj.foo; end
-        def obj.bar; end
+      all.uniq.should == [second]
+      inspects.uniq.should == ["#<TracePoint:line#{@path_prefix}#{__FILE__}:#{line}>"]
+      called.should == true
+    end
+  end
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
-          obj.bar
-        end
+  describe 'target: option' do
+    before :each do
+      ScratchPad.record []
+    end
 
-        ScratchPad.recorded.should == [:foo]
+    it 'enables trace point for specific location' do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
       end
 
-      it 'traces all the events triggered in specified location' do
-        trace = TracePoint.new(:line, :call, :return, :b_call, :b_return) do |tp|
-          ScratchPad << tp.event
-        end
+      obj = Object.new
+      def obj.foo; end
+      def obj.bar; end
 
-        obj = Object.new
-        def obj.foo
-          bar
-          -> {}.call
-        end
-        def obj.bar; end
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+        obj.bar
+      end
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
-        end
+      ScratchPad.recorded.should == [:foo]
+    end
 
-        ScratchPad.recorded.uniq.sort.should == [:call, :return, :b_call, :b_return, :line].sort
+    it 'traces all the events triggered in specified location' do
+      trace = TracePoint.new(:line, :call, :return, :b_call, :b_return) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.event
       end
 
-      it 'does not trace events in nested locations' do
-        trace = TracePoint.new(:call) do |tp|
-          ScratchPad << tp.method_id
-        end
+      obj = Object.new
+      def obj.foo
+        bar
+        -> {}.call
+      end
+      def obj.bar; end
 
-        obj = Object.new
-        def obj.foo
-          bar
-        end
-        def obj.bar
-          baz
-        end
-        def obj.baz
-        end
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+      end
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
-        end
+      ScratchPad.recorded.uniq.sort.should == [:call, :return, :b_call, :b_return, :line].sort
+    end
 
-        ScratchPad.recorded.should == [:foo]
+    it 'does not trace events in nested locations' do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
       end
 
-      it "traces some events in nested blocks" do
-        klass = Class.new do
-          def foo
+      obj = Object.new
+      def obj.foo
+        bar
+      end
+      def obj.bar
+        baz
+      end
+      def obj.baz
+      end
+
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+      end
+
+      ScratchPad.recorded.should == [:foo]
+    end
+
+    it "traces some events in nested blocks" do
+      klass = Class.new do
+        def foo
+          1.times do
             1.times do
-              1.times do
-                bar do
-                end
+              bar do
               end
             end
           end
+        end
 
-          def bar(&blk)
-            blk.call
-          end
+        def bar(&blk)
+          blk.call
         end
+      end
 
-        trace = TracePoint.new(:b_call) do |tp|
-          ScratchPad << tp.lineno
+      trace = TracePoint.new(:b_call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
+      end
+
+      obj = klass.new
+      _, lineno = obj.method(:foo).source_location
+
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+      end
+
+      ScratchPad.recorded.should == (lineno+1..lineno+3).to_a
+    end
+
+    describe 'option value' do
+      it 'accepts Method' do
+        trace = TracePoint.new(:call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << tp.method_id
         end
 
-        obj = klass.new
-        _, lineno = obj.method(:foo).source_location
+        obj = Object.new
+        def obj.foo; end
 
         trace.enable(target: obj.method(:foo)) do
           obj.foo
         end
 
-        ScratchPad.recorded.should == (lineno+1..lineno+3).to_a
+        ScratchPad.recorded.should == [:foo]
       end
 
-      describe 'option value' do
-        it 'accepts Method' do
-          trace = TracePoint.new(:call) do |tp|
-            ScratchPad << tp.method_id
-          end
-
-          obj = Object.new
-          def obj.foo; end
+      it 'accepts UnboundMethod' do
+        trace = TracePoint.new(:call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << tp.method_id
+        end
 
-          trace.enable(target: obj.method(:foo)) do
-            obj.foo
-          end
+        klass = Class.new do
+          def foo; end
+        end
 
-          ScratchPad.recorded.should == [:foo]
+        unbound_method = klass.instance_method(:foo)
+        trace.enable(target: unbound_method) do
+          klass.new.foo
         end
 
-        it 'accepts UnboundMethod' do
-          trace = TracePoint.new(:call) do |tp|
-            ScratchPad << tp.method_id
-          end
+        ScratchPad.recorded.should == [:foo]
+      end
 
-          klass = Class.new do
-            def foo; end
-          end
+      it 'accepts Proc' do
+        trace = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << tp.lineno
+        end
 
-          unbound_method = klass.instance_method(:foo)
-          trace.enable(target: unbound_method) do
-            klass.new.foo
-          end
+        block = proc {}
+        _, lineno = block.source_location
 
-          ScratchPad.recorded.should == [:foo]
+        trace.enable(target: block) do
+          block.call
         end
 
-        it 'accepts Proc' do
-          trace = TracePoint.new(:b_call) do |tp|
-            ScratchPad << tp.lineno
-          end
+        ScratchPad.recorded.should == [lineno]
+        lineno.should.is_a?(Integer)
+      end
+    end
 
-          block = proc {}
-          _, lineno = block.source_location
+    it "raises ArgumentError if target object cannot trigger specified event" do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
+      end
 
-          trace.enable(target: block) do
-            block.call
-          end
+      block = proc {}
 
-          ScratchPad.recorded.should == [lineno]
-          lineno.should be_kind_of(Integer)
+      -> {
+        trace.enable(target: block) do
+          block.call # triggers :b_call and :b_return events
         end
-      end
+      }.should.raise(ArgumentError, /can not enable any hooks/)
+    end
 
-      it "raises ArgumentError if target object cannot trigger specified event" do
-        trace = TracePoint.new(:call) do |tp|
-          ScratchPad << tp.method_id
+    it "raises ArgumentError if passed not Method/UnboundMethod/Proc" do
+      trace = TracePoint.new(:call) {}
+
+      -> {
+        trace.enable(target: Object.new) do
         end
+      }.should.raise(ArgumentError, /specified target is not supported/)
+    end
 
-        block = proc {}
+    context "nested enabling and disabling" do
+      it "raises ArgumentError if trace point already enabled with target is re-enabled with target" do
+        trace = TracePoint.new(:b_call) {}
 
         -> {
-          trace.enable(target: block) do
-            block.call # triggers :b_call and :b_return events
+          trace.enable(target: -> {}) do
+            trace.enable(target: -> {}) do
+            end
           end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
+        }.should.raise(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
       end
 
-      it "raises ArgumentError if passed not Method/UnboundMethod/Proc" do
-        trace = TracePoint.new(:call) do |tp|
-        end
+      it "raises ArgumentError if trace point already enabled without target is re-enabled with target" do
+        trace = TracePoint.new(:b_call) {}
 
         -> {
-          trace.enable(target: Object.new) do
+          trace.enable do
+            trace.enable(target: -> {}) do
+            end
           end
-        }.should raise_error(ArgumentError, /specified target is not supported/)
+        }.should.raise(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
       end
 
-      context "nested enabling and disabling" do
-        it "raises ArgumentError if trace point already enabled with target is re-enabled with target" do
-          trace = TracePoint.new(:b_call) do
-          end
+      it "raises ArgumentError if trace point already enabled with target is re-enabled without target" do
+        trace = TracePoint.new(:b_call) {}
 
-          -> {
-            trace.enable(target: -> {}) do
-              trace.enable(target: -> {}) do
-              end
+        -> {
+          trace.enable(target: -> {}) do
+            trace.enable do
             end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
-        end
-
-        it "raises ArgumentError if trace point already enabled without target is re-enabled with target" do
-          trace = TracePoint.new(:b_call) do
           end
+        }.should.raise(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+      end
 
-          -> {
-            trace.enable do
-              trace.enable(target: -> {}) do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
-        end
+      it "raises ArgumentError if trace point already enabled with target is disabled with block" do
+        trace = TracePoint.new(:b_call) {}
 
-        it "raises ArgumentError if trace point already enabled with target is re-enabled without target" do
-          trace = TracePoint.new(:b_call) do
+        -> {
+          trace.enable(target: -> {}) do
+            trace.disable do
+            end
           end
+        }.should.raise(ArgumentError, /can't disable a targett?ing TracePoint in a block/)
+      end
 
-          -> {
-            trace.enable(target: -> {}) do
-              trace.enable do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+      it "traces events when trace point with target is enabled in another trace point enabled without target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
         end
 
-        it "raises ArgumentError if trace point already enabled with target is disabled with block" do
-          trace = TracePoint.new(:b_call) do
-          end
-
-          -> {
-            trace.enable(target: -> {}) do
-              trace.disable do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't disable a targett?ing TracePoint in a block/)
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
         end
 
-        it "traces events when trace point with target is enabled in another trace point enabled without target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :outer
-          end
+        target = -> {}
 
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :inner
+        trace_outer.enable do
+          trace_inner.enable(target: target) do
+            target.call
           end
+        end
 
-          target = -> {}
+        ScratchPad.recorded.should == [:outer, :outer, :outer, :inner]
+      end
 
-          trace_outer.enable do
-            trace_inner.enable(target: target) do
-              target.call
-            end
-          end
+      it "traces events when trace point with target is enabled in another trace point enabled with target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
+        end
 
-          ScratchPad.recorded.should == [:outer, :outer, :outer, :inner]
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
         end
 
-        it "traces events when trace point with target is enabled in another trace point enabled with target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :outer
-          end
+        target = -> {}
 
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :inner
+        trace_outer.enable(target: target) do
+          trace_inner.enable(target: target) do
+            target.call
           end
+        end
 
-          target = -> {}
-
-          trace_outer.enable(target: target) do
-            trace_inner.enable(target: target) do
-              target.call
-            end
-          end
+        ScratchPad.recorded.should == [:inner, :outer]
+      end
 
-          ScratchPad.recorded.should == [:inner, :outer]
+      it "traces events when trace point without target is enabled in another trace point enabled with target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
         end
 
-        it "traces events when trace point without target is enabled in another trace point enabled with target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :outer
-          end
-
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            ScratchPad << :inner
-          end
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
+        end
 
-          target = -> {}
+        target = -> {}
 
-          trace_outer.enable(target: target) do
-            trace_inner.enable do
-              target.call
-            end
+        trace_outer.enable(target: target) do
+          trace_inner.enable do
+            target.call
           end
-
-          ScratchPad.recorded.should == [:inner, :inner, :outer]
         end
-      end
-    end
 
-    describe 'target_line: option' do
-      before :each do
-        ScratchPad.record []
+        ScratchPad.recorded.should == [:inner, :inner, :outer]
       end
+    end
+  end
 
-      it "traces :line events only on specified line of code" do
-        trace = TracePoint.new(:line) do |tp|
-          ScratchPad << tp.lineno
-        end
+  describe 'target_line: option' do
+    before :each do
+      ScratchPad.record []
+    end
 
-        target = -> {
-          x = 1
-          y = 2      # <= this line is target
-          z = x + y
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 2
+    it "traces :line events only on specified line of code" do
+      trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
+      end
 
-        trace.enable(target_line: target_line, target: target) do
-          target.call
-        end
+      target = -> {
+        x = 1
+        y = 2      # <= this line is target
+        z = x + y
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 2
 
-        ScratchPad.recorded.should == [target_line]
+      trace.enable(target_line: target_line, target: target) do
+        target.call
       end
 
-      it "raises ArgumentError if :target option isn't specified" do
-        trace = TracePoint.new(:line) do |tp|
-        end
+      ScratchPad.recorded.should == [target_line]
+    end
 
-        -> {
-          trace.enable(target_line: 67) do
-          end
-        }.should raise_error(ArgumentError, /only target_line is specified/)
-      end
+    it "raises ArgumentError if :target option isn't specified" do
+      trace = TracePoint.new(:line) {}
 
-      it "raises ArgumentError if :line event isn't registered" do
-        trace = TracePoint.new(:call) do |tp|
+      -> {
+        trace.enable(target_line: 67) do
         end
+      }.should.raise(ArgumentError, /only target_line is specified/)
+    end
 
-        target = -> {
-          x = 1
-          y = 2     # <= this line is target
-          z = x + y
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 2
+    it "raises ArgumentError if :line event isn't registered" do
+      trace = TracePoint.new(:call) {}
 
-        -> {
-          trace.enable(target_line: target_line, target: target) do
-          end
-        }.should raise_error(ArgumentError, /target_line is specified, but line event is not specified/)
-      end
+      target = -> {
+        x = 1
+        y = 2     # <= this line is target
+        z = x + y
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 2
 
-      it "raises ArgumentError if :target_line value is out of target code lines range" do
-        trace = TracePoint.new(:line) do |tp|
+      -> {
+        trace.enable(target_line: target_line, target: target) do
         end
+      }.should.raise(ArgumentError, /target_line is specified, but line event is not specified/)
+    end
 
-        -> {
-          trace.enable(target_line: 1, target: -> { }) do
-          end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
-      end
+    it "raises ArgumentError if :target_line value is out of target code lines range" do
+      trace = TracePoint.new(:line) {}
 
-      it "raises TypeError if :target_line value couldn't be coerced to Integer" do
-        trace = TracePoint.new(:line) do |tp|
+      -> {
+        trace.enable(target_line: 1, target: -> { }) do
         end
+      }.should.raise(ArgumentError, /can not enable any hooks/)
+    end
 
-        -> {
-          trace.enable(target_line: Object.new, target: -> { }) do
-          end
-        }.should raise_error(TypeError, /no implicit conversion of \w+? into Integer/)
-      end
+    it "raises TypeError if :target_line value couldn't be coerced to Integer" do
+      trace = TracePoint.new(:line) {}
 
-      it "raises ArgumentError if :target_line value is negative" do
-        trace = TracePoint.new(:line) do |tp|
+      -> {
+        trace.enable(target_line: Object.new, target: -> { }) do
         end
+      }.should.raise(TypeError, /no implicit conversion of \w+? into Integer/)
+    end
 
-        -> {
-          trace.enable(target_line: -2, target: -> { }) do
-          end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
-      end
+    it "raises ArgumentError if :target_line value is negative" do
+      trace = TracePoint.new(:line) {}
 
-      it "accepts value that could be coerced to Integer" do
-        trace = TracePoint.new(:line) do |tp|
-          ScratchPad << tp.lineno
+      -> {
+        trace.enable(target_line: -2, target: -> { }) do
         end
+      }.should.raise(ArgumentError, /can not enable any hooks/)
+    end
 
-        target = -> {
-          x = 1         #  <= this line is target
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 1
+    it "accepts value that could be coerced to Integer" do
+      trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
+      end
 
-        trace.enable(target_line: target_line.to_r, target: target) do
-          target.call
-        end
+      target = -> {
+        x = 1         #  <= this line is target
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 1
 
-        ScratchPad.recorded.should == [target_line]
+      trace.enable(target_line: target_line.to_r, target: target) do
+        target.call
       end
+
+      ScratchPad.recorded.should == [target_line]
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/enabled_spec.rb b/spec/ruby/core/tracepoint/enabled_spec.rb
index 0167d32fb0..0e9566a02c 100644
--- a/spec/ruby/core/tracepoint/enabled_spec.rb
+++ b/spec/ruby/core/tracepoint/enabled_spec.rb
@@ -1,14 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#enabled?' do
   it 'returns true when current status of the trace is enable' do
     trace = TracePoint.new(:line) {}
     trace.enable do
-      trace.enabled?.should == true
+      trace.should.enabled?
     end
   end
 
   it 'returns false when current status of the trace is disabled' do
-    TracePoint.new(:line) {}.enabled?.should == false
+    TracePoint.new(:line) {}.should_not.enabled?
   end
 end
diff --git a/spec/ruby/core/tracepoint/eval_script_spec.rb b/spec/ruby/core/tracepoint/eval_script_spec.rb
index 1d8e425a9a..7ec53e7094 100644
--- a/spec/ruby/core/tracepoint/eval_script_spec.rb
+++ b/spec/ruby/core/tracepoint/eval_script_spec.rb
@@ -1,24 +1,23 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "TracePoint#eval_script" do
-    it "is the evald source code" do
-      ScratchPad.record []
+describe "TracePoint#eval_script" do
+  it "is the evald source code" do
+    ScratchPad.record []
 
-      script = <<-CODE
-        def foo
-          p :hello
-        end
-      CODE
-
-      TracePoint.new(:script_compiled) do |e|
-        ScratchPad << e.eval_script
-      end.enable do
-        eval script
+    script = <<-CODE
+      def foo
+        p :hello
       end
+    CODE
 
-      ScratchPad.recorded.should == [script]
+    TracePoint.new(:script_compiled) do |e|
+      next unless TracePointSpec.target_thread?
+      ScratchPad << e.eval_script
+    end.enable do
+      eval script
     end
+
+    ScratchPad.recorded.should == [script]
   end
 end
diff --git a/spec/ruby/core/tracepoint/event_spec.rb b/spec/ruby/core/tracepoint/event_spec.rb
index 019d0c3253..58017dc98d 100644
--- a/spec/ruby/core/tracepoint/event_spec.rb
+++ b/spec/ruby/core/tracepoint/event_spec.rb
@@ -5,16 +5,17 @@ describe 'TracePoint#event' do
   it 'returns the type of event' do
     event_name = nil
     TracePoint.new(:end, :call) do |tp|
+      next unless TracePointSpec.target_thread?
       event_name = tp.event
     end.enable do
       TracePointSpec.test
-      event_name.should equal(:call)
+      event_name.should.equal?(:call)
 
       TracePointSpec::B.new.foo
-      event_name.should equal(:call)
+      event_name.should.equal?(:call)
 
       class TracePointSpec::B; end
-      event_name.should equal(:end)
+      event_name.should.equal?(:end)
     end
 
   end
diff --git a/spec/ruby/core/tracepoint/fixtures/classes.rb b/spec/ruby/core/tracepoint/fixtures/classes.rb
index 49c70e1915..3ab1b00b16 100644
--- a/spec/ruby/core/tracepoint/fixtures/classes.rb
+++ b/spec/ruby/core/tracepoint/fixtures/classes.rb
@@ -1,4 +1,10 @@
 module TracePointSpec
+  @thread = Thread.current
+
+  def self.target_thread?
+    Thread.current == @thread
+  end
+
   class ClassWithMethodAlias
     def m
     end
diff --git a/spec/ruby/core/tracepoint/inspect_spec.rb b/spec/ruby/core/tracepoint/inspect_spec.rb
index 9ff1653ae8..6cc2ebe243 100644
--- a/spec/ruby/core/tracepoint/inspect_spec.rb
+++ b/spec/ruby/core/tracepoint/inspect_spec.rb
@@ -2,27 +2,140 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe 'TracePoint#inspect' do
+  before do
+    @path_prefix = ' '
+  end
+
   it 'returns a string containing a human-readable TracePoint status' do
-    TracePoint.new(:line) {}.inspect.should ==
-      '#<TracePoint:disabled>'
+    TracePoint.new(:line) {}.inspect.should == '#<TracePoint:disabled>'
+  end
+
+  it "shows only whether it's enabled when outside the TracePoint handler" do
+    trace = TracePoint.new(:line) {}
+    trace.enable
+
+    trace.inspect.should == '#<TracePoint:enabled>'
+
+    trace.disable
   end
 
   it 'returns a String showing the event, path and line' do
     inspect = nil
-    line = __LINE__
-    TracePoint.new(:line) { |tp| inspect = tp.inspect }.enable do
-      inspect.should == "#<TracePoint:line@#{__FILE__}:#{line+2}>"
+    line = nil
+    TracePoint.new(:line) { |tp|
+      next unless TracePointSpec.target_thread?
+      next unless tp.path == __FILE__
+
+      inspect ||= tp.inspect
+    }.enable do
+      line = __LINE__
+    end
+
+    inspect.should == "#<TracePoint:line#{@path_prefix}#{__FILE__}:#{line}>"
+  end
+
+  it 'returns a String showing the event, method, path and line for a :call event' do
+    inspect = nil
+    line = nil
+    TracePoint.new(:call) { |tp|
+      next unless TracePointSpec.target_thread?
+      next unless tp.path == __FILE__
+
+      inspect ||= tp.inspect
+    }.enable do
+      line = __LINE__ + 1
+      def trace_point_spec_test_call; end
+      trace_point_spec_test_call
+    end
+
+    inspect.should =~ /\A#<TracePoint:call [`']trace_point_spec_test_call'#{@path_prefix}#{__FILE__}:#{line}>\z/
+  end
+
+  it 'returns a String showing the event, method, path and line for a :return event' do
+    inspect = nil
+    line = nil
+    TracePoint.new(:return) { |tp|
+      next unless TracePointSpec.target_thread?
+      next unless tp.path == __FILE__
+
+      inspect ||= tp.inspect
+    }.enable do
+      line = __LINE__ + 4
+      def trace_point_spec_test_return
+        a = 1
+        return a
+      end
+      trace_point_spec_test_return
+    end
+    ruby_version_is("3.4") { line -= 1 }
+
+    inspect.should =~ /\A#<TracePoint:return [`']trace_point_spec_test_return'#{@path_prefix}#{__FILE__}:#{line}>\z/
+  end
+
+  it 'returns a String showing the event, method, path and line for a :c_call event' do
+    inspect = nil
+    tracepoint = TracePoint.new(:c_call) { |tp|
+      next unless TracePointSpec.target_thread?
+      next unless tp.path == __FILE__
+
+      inspect ||= tp.inspect
+    }
+    line = __LINE__ + 2
+    tracepoint.enable do
+      [0, 1].max
     end
+
+    inspect.should =~ /\A#<TracePoint:c_call [`']max'#{@path_prefix}#{__FILE__}:#{line}>\z/
   end
 
   it 'returns a String showing the event, path and line for a :class event' do
     inspect = nil
-    line = __LINE__
-    TracePoint.new(:class) { |tp| inspect = tp.inspect }.enable do
+    line = nil
+    TracePoint.new(:class) { |tp|
+      next unless TracePointSpec.target_thread?
+      next unless tp.path == __FILE__
+
+      inspect ||= tp.inspect
+    }.enable do
+      line = __LINE__ + 1
       class TracePointSpec::C
       end
     end
 
-    inspect.should == "#<TracePoint:class@#{__FILE__}:#{line+2}>"
+    inspect.should == "#<TracePoint:class#{@path_prefix}#{__FILE__}:#{line}>"
+  end
+
+  it 'returns a String showing the event and thread for :thread_begin event' do
+    inspect = nil
+    thread = nil
+    thread_inspection = nil
+    TracePoint.new(:thread_begin) { |tp|
+      next unless Thread.current == thread
+
+      inspect ||= tp.inspect
+    }.enable(target_thread: nil) do
+      thread = Thread.new {}
+      thread_inspection = thread.inspect
+      thread.join
+    end
+
+    inspect.should == "#<TracePoint:thread_begin #{thread_inspection}>"
+  end
+
+  it 'returns a String showing the event and thread for :thread_end event' do
+    inspect = nil
+    thread = nil
+    thread_inspection = nil
+    TracePoint.new(:thread_end) { |tp|
+      next unless Thread.current == thread
+
+      inspect ||= tp.inspect
+    }.enable(target_thread: nil) do
+      thread = Thread.new {}
+      thread_inspection = thread.inspect
+      thread.join
+    end
+
+    inspect.should == "#<TracePoint:thread_end #{thread_inspection}>"
   end
 end
diff --git a/spec/ruby/core/tracepoint/lineno_spec.rb b/spec/ruby/core/tracepoint/lineno_spec.rb
index a4d7e77e8d..7c46d5222b 100644
--- a/spec/ruby/core/tracepoint/lineno_spec.rb
+++ b/spec/ruby/core/tracepoint/lineno_spec.rb
@@ -1,10 +1,20 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#lineno' do
   it 'returns the line number of the event' do
     lineno = nil
-    TracePoint.new(:line) { |tp| lineno = tp.lineno }.enable do
-      lineno.should == 7
+    TracePoint.new(:line) { |tp|
+      next unless TracePointSpec.target_thread?
+      lineno = tp.lineno
+    }.enable do
+      line_event = true
     end
+    lineno.should == __LINE__ - 2
+  end
+
+  it 'raises RuntimeError if accessed from outside' do
+    tp = TracePoint.new(:line) {}
+    -> { tp.lineno }.should.raise(RuntimeError, 'access from outside')
   end
 end
diff --git a/spec/ruby/core/tracepoint/method_id_spec.rb b/spec/ruby/core/tracepoint/method_id_spec.rb
index 82254d1299..67740f2d7d 100644
--- a/spec/ruby/core/tracepoint/method_id_spec.rb
+++ b/spec/ruby/core/tracepoint/method_id_spec.rb
@@ -1,13 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#method_id' do
-  def test; end
-
   it 'returns the name at the definition of the method being called' do
     method_name = nil
-    TracePoint.new(:call) { |tp| method_name = tp.method_id}.enable do
-      test
-      method_name.should equal(:test)
+    TracePoint.new(:call) { |tp|
+      next unless TracePointSpec.target_thread?
+      method_name = tp.method_id
+    }.enable do
+      TracePointSpec.test
+      method_name.should.equal?(:test)
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/new_spec.rb b/spec/ruby/core/tracepoint/new_spec.rb
index 916d826fdf..763b35292b 100644
--- a/spec/ruby/core/tracepoint/new_spec.rb
+++ b/spec/ruby/core/tracepoint/new_spec.rb
@@ -3,21 +3,24 @@ require_relative 'fixtures/classes'
 
 describe 'TracePoint.new' do
   it 'returns a new TracePoint object, not enabled by default' do
-    TracePoint.new(:line) {}.enabled?.should be_false
+    TracePoint.new(:line) {}.enabled?.should == false
   end
 
   it 'includes :line event when event is not specified' do
     event_name = nil
-    TracePoint.new() { |tp| event_name = tp.event }.enable do
-      event_name.should equal(:line)
+    TracePoint.new { |tp|
+      next unless TracePointSpec.target_thread?
+      event_name = tp.event
+    }.enable do
+      event_name.should.equal?(:line)
 
       event_name = nil
       TracePointSpec.test
-      event_name.should equal(:line)
+      event_name.should.equal?(:line)
 
       event_name = nil
       TracePointSpec::B.new.foo
-      event_name.should equal(:line)
+      event_name.should.equal?(:line)
     end
   end
 
@@ -25,7 +28,10 @@ describe 'TracePoint.new' do
     event_name = nil
     (o = mock('line')).should_receive(:to_sym).and_return(:line)
 
-    TracePoint.new(o) { |tp| event_name = tp.event }.enable do
+    TracePoint.new(o) { |tp|
+      next unless TracePointSpec.target_thread?
+      event_name = tp.event
+    }.enable do
       line_event = true
       event_name.should == :line
     end
@@ -34,34 +40,33 @@ describe 'TracePoint.new' do
   it 'includes multiple events when multiple event names are passed as params' do
     event_name = nil
     TracePoint.new(:end, :call) do |tp|
+      next unless TracePointSpec.target_thread?
       event_name = tp.event
     end.enable do
       TracePointSpec.test
-      event_name.should equal(:call)
+      event_name.should.equal?(:call)
 
       TracePointSpec::B.new.foo
-      event_name.should equal(:call)
+      event_name.should.equal?(:call)
 
       class TracePointSpec::B; end
-      event_name.should equal(:end)
+      event_name.should.equal?(:end)
     end
   end
 
   it 'raises a TypeError when the given object is not a string/symbol' do
     o = mock('123')
-    -> { TracePoint.new(o) {}}.should raise_error(TypeError)
+    -> { TracePoint.new(o) {} }.should.raise(TypeError)
 
     o.should_receive(:to_sym).and_return(123)
-    -> { TracePoint.new(o) {}}.should raise_error(TypeError)
+    -> { TracePoint.new(o) {} }.should.raise(TypeError)
   end
 
-  ruby_version_is "2.5" do
-    it 'expects to be called with a block' do
-      -> { TracePoint.new(:line) }.should raise_error(ArgumentError, "must be called with a block")
-    end
+  it 'expects to be called with a block' do
+    -> { TracePoint.new(:line) }.should.raise(ArgumentError, "must be called with a block")
   end
 
   it "raises a Argument error when the given argument doesn't match an event name" do
-    -> { TracePoint.new(:test) }.should raise_error(ArgumentError, "unknown event: test")
+    -> { TracePoint.new(:test) }.should.raise(ArgumentError, "unknown event: test")
   end
 end
diff --git a/spec/ruby/core/tracepoint/parameters_spec.rb b/spec/ruby/core/tracepoint/parameters_spec.rb
index f901c184f4..82aee3caa4 100644
--- a/spec/ruby/core/tracepoint/parameters_spec.rb
+++ b/spec/ruby/core/tracepoint/parameters_spec.rb
@@ -1,23 +1,28 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe 'TracePoint#parameters' do
-    it 'returns the parameters of block' do
-      f = proc {|x, y, z| }
-      parameters = nil
-      TracePoint.new(:b_call) {|tp| parameters = tp.parameters }.enable do
-        f.call
-        parameters.should == [[:opt, :x], [:opt, :y], [:opt, :z]]
-      end
+describe 'TracePoint#parameters' do
+  it 'returns the parameters of block' do
+    f = proc {|x, y, z| }
+    parameters = nil
+    TracePoint.new(:b_call) { |tp|
+      next unless TracePointSpec.target_thread?
+      parameters = tp.parameters
+    }.enable do
+      f.call
+      parameters.should == [[:opt, :x], [:opt, :y], [:opt, :z]]
     end
+  end
 
-    it 'returns the parameters of lambda block' do
-      f = -> x, y, z { }
-      parameters = nil
-      TracePoint.new(:b_call) {|tp| parameters = tp.parameters }.enable do
-        f.call(1, 2, 3)
-        parameters.should == [[:req, :x], [:req, :y], [:req, :z]]
-      end
+  it 'returns the parameters of lambda block' do
+    f = -> x, y, z { }
+    parameters = nil
+    TracePoint.new(:b_call) { |tp|
+      next unless TracePointSpec.target_thread?
+      parameters = tp.parameters
+    }.enable do
+      f.call(1, 2, 3)
+      parameters.should == [[:req, :x], [:req, :y], [:req, :z]]
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/path_spec.rb b/spec/ruby/core/tracepoint/path_spec.rb
index 1e31c1bb68..aa6868ead2 100644
--- a/spec/ruby/core/tracepoint/path_spec.rb
+++ b/spec/ruby/core/tracepoint/path_spec.rb
@@ -1,18 +1,26 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#path' do
   it 'returns the path of the file being run' do
     path = nil
-    TracePoint.new(:line) { |tp| path = tp.path }.enable do
-      path.should == "#{__FILE__}"
+    TracePoint.new(:line) { |tp|
+      next unless TracePointSpec.target_thread?
+      path = tp.path
+    }.enable do
+      line_event = true
     end
+    path.should == "#{__FILE__}"
   end
 
-  it 'equals (eval) inside an eval for :end event' do
+  it 'equals "(eval at __FILE__:__LINE__)" inside an eval for :end event' do
     path = nil
-    TracePoint.new(:end) { |tp| path = tp.path }.enable do
+    TracePoint.new(:end) { |tp|
+      next unless TracePointSpec.target_thread?
+      path = tp.path
+    }.enable do
       eval("module TracePointSpec; end")
-      path.should == '(eval)'
     end
+    path.should == "(eval at #{__FILE__}:#{__LINE__ - 2})"
   end
 end
diff --git a/spec/ruby/core/tracepoint/raised_exception_spec.rb b/spec/ruby/core/tracepoint/raised_exception_spec.rb
index 450717b958..b1199902f2 100644
--- a/spec/ruby/core/tracepoint/raised_exception_spec.rb
+++ b/spec/ruby/core/tracepoint/raised_exception_spec.rb
@@ -1,16 +1,36 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#raised_exception' do
   it 'returns value from exception raised on the :raise event' do
     raised_exception, error_result = nil
-    trace = TracePoint.new(:raise) { |tp| raised_exception = tp.raised_exception }
+    trace = TracePoint.new(:raise) { |tp|
+      next unless TracePointSpec.target_thread?
+      raised_exception = tp.raised_exception
+    }
     trace.enable do
       begin
         raise StandardError
       rescue => e
         error_result = e
       end
-      raised_exception.should equal(error_result)
+      raised_exception.should.equal?(error_result)
+    end
+  end
+
+  it 'returns value from exception rescued on the :rescue event' do
+    raised_exception, error_result = nil
+    trace = TracePoint.new(:rescue) { |tp|
+      next unless TracePointSpec.target_thread?
+      raised_exception = tp.raised_exception
+    }
+    trace.enable do
+      begin
+        raise StandardError
+      rescue => e
+        error_result = e
+      end
+      raised_exception.should.equal?(error_result)
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/return_value_spec.rb b/spec/ruby/core/tracepoint/return_value_spec.rb
index f0ed86bd00..e84c7dd762 100644
--- a/spec/ruby/core/tracepoint/return_value_spec.rb
+++ b/spec/ruby/core/tracepoint/return_value_spec.rb
@@ -1,11 +1,15 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint#return_value' do
   def test; 'test' end
 
   it 'returns value from :return event' do
     trace_value = nil
-    TracePoint.new(:return) { |tp| trace_value = tp.return_value}.enable do
+    TracePoint.new(:return) { |tp|
+      next unless TracePointSpec.target_thread?
+      trace_value = tp.return_value
+    }.enable do
       test
       trace_value.should == 'test'
     end
diff --git a/spec/ruby/core/tracepoint/self_spec.rb b/spec/ruby/core/tracepoint/self_spec.rb
index 8bfd09301e..bf9a2b6a45 100644
--- a/spec/ruby/core/tracepoint/self_spec.rb
+++ b/spec/ruby/core/tracepoint/self_spec.rb
@@ -4,17 +4,23 @@ require_relative 'fixtures/classes'
 describe 'TracePoint#self' do
   it 'return the trace object from event' do
     trace = nil
-    TracePoint.new(:line) { |tp| trace = tp.self }.enable do
-      trace.equal?(self).should be_true
+    TracePoint.new(:line) { |tp|
+      next unless TracePointSpec.target_thread?
+      trace = tp.self
+    }.enable do
+      trace.equal?(self).should == true
     end
   end
 
   it 'return the class object from a class event' do
     trace = nil
-    TracePoint.new(:class) { |tp| trace = tp.self }.enable do
+    TracePoint.new(:class) { |tp|
+      next unless TracePointSpec.target_thread?
+      trace = tp.self
+    }.enable do
       class TracePointSpec::C
       end
     end
-    trace.should equal TracePointSpec::C
+    trace.should.equal? TracePointSpec::C
   end
 end
diff --git a/spec/ruby/core/tracepoint/trace_spec.rb b/spec/ruby/core/tracepoint/trace_spec.rb
index ea6c85bcc5..167f594bb9 100644
--- a/spec/ruby/core/tracepoint/trace_spec.rb
+++ b/spec/ruby/core/tracepoint/trace_spec.rb
@@ -1,9 +1,10 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe 'TracePoint.trace' do
   it 'activates the trace automatically' do
     trace = TracePoint.trace(:line) {}
-    trace.enabled?.should == true
+    trace.should.enabled?
     trace.disable
   end
 end
diff --git a/spec/ruby/core/true/case_compare_spec.rb b/spec/ruby/core/true/case_compare_spec.rb
new file mode 100644
index 0000000000..dee6dd0227
--- /dev/null
+++ b/spec/ruby/core/true/case_compare_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "TrueClass#===" do
+  it "returns true for true" do
+    (true === true).should == true
+  end
+
+  it "returns false for non-true object" do
+    (true === 1).should == false
+    (true === "").should == false
+    (true === Object).should == false
+  end
+end
diff --git a/spec/ruby/core/true/dup_spec.rb b/spec/ruby/core/true/dup_spec.rb
index 351457ed22..2628f6d374 100644
--- a/spec/ruby/core/true/dup_spec.rb
+++ b/spec/ruby/core/true/dup_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "TrueClass#dup" do
   it "returns self" do
-    true.dup.should equal(true)
+    true.dup.should.equal?(true)
   end
 end
diff --git a/spec/ruby/core/true/singleton_method_spec.rb b/spec/ruby/core/true/singleton_method_spec.rb
new file mode 100644
index 0000000000..58689fb6e5
--- /dev/null
+++ b/spec/ruby/core/true/singleton_method_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "TrueClass#singleton_method" do
+  it "raises regardless of whether TrueClass defines the method" do
+    -> { true.singleton_method(:foo) }.should.raise(NameError)
+    begin
+      def (true).foo; end
+      -> { true.singleton_method(:foo) }.should.raise(NameError)
+    ensure
+      TrueClass.send(:remove_method, :foo)
+    end
+  end
+end
diff --git a/spec/ruby/core/true/to_s_spec.rb b/spec/ruby/core/true/to_s_spec.rb
index 68b0052c5d..2c6f3889e9 100644
--- a/spec/ruby/core/true/to_s_spec.rb
+++ b/spec/ruby/core/true/to_s_spec.rb
@@ -5,13 +5,11 @@ describe "TrueClass#to_s" do
     true.to_s.should == "true"
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen string" do
-      true.to_s.frozen?.should == true
-    end
+  it "returns a frozen string" do
+    true.to_s.should.frozen?
+  end
 
-    it "always returns the same string" do
-      true.to_s.should equal(true.to_s)
-    end
+  it "always returns the same string" do
+    true.to_s.should.equal?(true.to_s)
   end
 end
diff --git a/spec/ruby/core/true/trueclass_spec.rb b/spec/ruby/core/true/trueclass_spec.rb
index 02af649d09..1c1a0ddbe2 100644
--- a/spec/ruby/core/true/trueclass_spec.rb
+++ b/spec/ruby/core/true/trueclass_spec.rb
@@ -4,12 +4,12 @@ describe "TrueClass" do
   it ".allocate raises a TypeError" do
     -> do
       TrueClass.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       TrueClass.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/unboundmethod/bind_call_spec.rb b/spec/ruby/core/unboundmethod/bind_call_spec.rb
index c5d392156c..ee1dad9c9e 100644
--- a/spec/ruby/core/unboundmethod/bind_call_spec.rb
+++ b/spec/ruby/core/unboundmethod/bind_call_spec.rb
@@ -1,52 +1,58 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is '2.7' do
-  describe "UnboundMethod#bind_call" do
-    before :each do
-      @normal_um = UnboundMethodSpecs::Methods.new.method(:foo).unbind
-      @parent_um = UnboundMethodSpecs::Parent.new.method(:foo).unbind
-      @child1_um = UnboundMethodSpecs::Child1.new.method(:foo).unbind
-      @child2_um = UnboundMethodSpecs::Child2.new.method(:foo).unbind
-    end
+describe "UnboundMethod#bind_call" do
+  before :each do
+    @normal_um = UnboundMethodSpecs::Methods.new.method(:foo).unbind
+    @parent_um = UnboundMethodSpecs::Parent.new.method(:foo).unbind
+    @child1_um = UnboundMethodSpecs::Child1.new.method(:foo).unbind
+    @child2_um = UnboundMethodSpecs::Child2.new.method(:foo).unbind
+    @normal_um_super = UnboundMethodSpecs::Mod.instance_method(:foo_super)
+    @parent_um_super = UnboundMethodSpecs::Parent.new.method(:foo_super).unbind
+  end
 
-    it "raises TypeError if object is not kind_of? the Module the method defined in" do
-      -> { @normal_um.bind_call(UnboundMethodSpecs::B.new) }.should raise_error(TypeError)
-    end
+  it "raises TypeError if object is not kind_of? the Module the method defined in" do
+    -> { @normal_um.bind_call(UnboundMethodSpecs::B.new) }.should.raise(TypeError)
+  end
 
-    it "binds and calls the method if object is kind_of the Module the method defined in" do
-      @normal_um.bind_call(UnboundMethodSpecs::Methods.new).should == true
-    end
+  it "binds and calls the method if object is kind_of the Module the method defined in" do
+    @normal_um.bind_call(UnboundMethodSpecs::Methods.new).should == true
+  end
 
-    it "binds and calls the method on any object when UnboundMethod is unbound from a module" do
-      UnboundMethodSpecs::Mod.instance_method(:from_mod).bind_call(Object.new).should == nil
-    end
+  it "binds and calls the method on any object when UnboundMethod is unbound from a module" do
+    UnboundMethodSpecs::Mod.instance_method(:from_mod).bind_call(Object.new).should == nil
+  end
 
-    it "binds and calls the method for any object kind_of? the Module the method is defined in" do
-      @parent_um.bind_call(UnboundMethodSpecs::Child1.new).should == nil
-      @child1_um.bind_call(UnboundMethodSpecs::Parent.new).should == nil
-      @child2_um.bind_call(UnboundMethodSpecs::Child1.new).should == nil
-    end
+  it "binds and calls the method for any object kind_of? the Module the method is defined in" do
+    @parent_um.bind_call(UnboundMethodSpecs::Child1.new).should == nil
+    @child1_um.bind_call(UnboundMethodSpecs::Parent.new).should == nil
+    @child2_um.bind_call(UnboundMethodSpecs::Child1.new).should == nil
+  end
 
-    it "binds and calls a Kernel method retrieved from Object on BasicObject" do
-      Object.instance_method(:instance_of?).bind_call(BasicObject.new, BasicObject).should == true
-    end
+  it "binds and calls a Kernel method retrieved from Object on BasicObject" do
+    Object.instance_method(:instance_of?).bind_call(BasicObject.new, BasicObject).should == true
+  end
 
-    it "binds and calls a Parent's class method to any Child's class methods" do
-      um = UnboundMethodSpecs::Parent.method(:class_method).unbind
-      um.bind_call(UnboundMethodSpecs::Child1).should == "I am UnboundMethodSpecs::Child1"
-    end
+  it "binds and calls a Parent's class method to any Child's class methods" do
+    um = UnboundMethodSpecs::Parent.method(:class_method).unbind
+    um.bind_call(UnboundMethodSpecs::Child1).should == "I am UnboundMethodSpecs::Child1"
+  end
 
-    it "will raise when binding a an object singleton's method to another object" do
-      other = UnboundMethodSpecs::Parent.new
-      p = UnboundMethodSpecs::Parent.new
-      class << p
-        def singleton_method
-          :single
-        end
+  it "will raise when binding a an object singleton's method to another object" do
+    other = UnboundMethodSpecs::Parent.new
+    p = UnboundMethodSpecs::Parent.new
+    class << p
+      def singleton_method
+        :single
       end
-      um = p.method(:singleton_method).unbind
-      ->{ um.bind_call(other) }.should raise_error(TypeError)
     end
+    um = p.method(:singleton_method).unbind
+    ->{ um.bind_call(other) }.should.raise(TypeError)
+  end
+
+  it "allows calling super for module methods bound to hierarchies that do not already have that module" do
+    p = UnboundMethodSpecs::Parent.new
+
+    @normal_um_super.bind_call(p).should == true
   end
 end
diff --git a/spec/ruby/core/unboundmethod/bind_spec.rb b/spec/ruby/core/unboundmethod/bind_spec.rb
index 03aaa22e74..087994ff57 100644
--- a/spec/ruby/core/unboundmethod/bind_spec.rb
+++ b/spec/ruby/core/unboundmethod/bind_spec.rb
@@ -7,18 +7,20 @@ describe "UnboundMethod#bind" do
     @parent_um = UnboundMethodSpecs::Parent.new.method(:foo).unbind
     @child1_um = UnboundMethodSpecs::Child1.new.method(:foo).unbind
     @child2_um = UnboundMethodSpecs::Child2.new.method(:foo).unbind
+    @normal_um_super = UnboundMethodSpecs::Mod.instance_method(:foo_super)
+    @parent_um_super = UnboundMethodSpecs::Parent.new.method(:foo_super).unbind
   end
 
   it "raises TypeError if object is not kind_of? the Module the method defined in" do
-    -> { @normal_um.bind(UnboundMethodSpecs::B.new) }.should raise_error(TypeError)
+    -> { @normal_um.bind(UnboundMethodSpecs::B.new) }.should.raise(TypeError)
   end
 
   it "returns Method for any object that is kind_of? the Module method was extracted from" do
-    @normal_um.bind(UnboundMethodSpecs::Methods.new).should be_kind_of(Method)
+    @normal_um.bind(UnboundMethodSpecs::Methods.new).should.is_a?(Method)
   end
 
   it "returns Method on any object when UnboundMethod is unbound from a module" do
-    UnboundMethodSpecs::Mod.instance_method(:from_mod).bind(Object.new).should be_kind_of(Method)
+    UnboundMethodSpecs::Mod.instance_method(:from_mod).bind(Object.new).should.is_a?(Method)
   end
 
   it "the returned Method is equal to the one directly returned by obj.method" do
@@ -27,9 +29,9 @@ describe "UnboundMethod#bind" do
   end
 
   it "returns Method for any object kind_of? the Module the method is defined in" do
-    @parent_um.bind(UnboundMethodSpecs::Child1.new).should be_kind_of(Method)
-    @child1_um.bind(UnboundMethodSpecs::Parent.new).should be_kind_of(Method)
-    @child2_um.bind(UnboundMethodSpecs::Child1.new).should be_kind_of(Method)
+    @parent_um.bind(UnboundMethodSpecs::Child1.new).should.is_a?(Method)
+    @child1_um.bind(UnboundMethodSpecs::Parent.new).should.is_a?(Method)
+    @child2_um.bind(UnboundMethodSpecs::Child1.new).should.is_a?(Method)
   end
 
   it "allows binding a Kernel method retrieved from Object on BasicObject" do
@@ -43,7 +45,7 @@ describe "UnboundMethod#bind" do
 
   it "binds a Parent's class method to any Child's class methods" do
     m = UnboundMethodSpecs::Parent.method(:class_method).unbind.bind(UnboundMethodSpecs::Child1)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == "I am UnboundMethodSpecs::Child1"
   end
 
@@ -56,6 +58,12 @@ describe "UnboundMethod#bind" do
       end
     end
     um = p.method(:singleton_method).unbind
-    ->{ um.bind(other) }.should raise_error(TypeError)
+    ->{ um.bind(other) }.should.raise(TypeError)
+  end
+
+  it "allows calling super for module methods bound to hierarchies that do not already have that module" do
+    p = UnboundMethodSpecs::Parent.new
+
+    @normal_um_super.bind(p).call.should == true
   end
 end
diff --git a/spec/ruby/core/unboundmethod/clone_spec.rb b/spec/ruby/core/unboundmethod/clone_spec.rb
index 098ee61476..1e7fb18744 100644
--- a/spec/ruby/core/unboundmethod/clone_spec.rb
+++ b/spec/ruby/core/unboundmethod/clone_spec.rb
@@ -1,12 +1,13 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/classes'
+require_relative 'shared/dup'
 
 describe "UnboundMethod#clone" do
-  it "returns a copy of the UnboundMethod" do
-    um1 = UnboundMethodSpecs::Methods.instance_method(:foo)
-    um2 = um1.clone
+  it_behaves_like :unboundmethod_dup, :clone
 
-    (um1 == um2).should == true
-    um1.bind(UnboundMethodSpecs::Methods.new).call.should == um2.bind(UnboundMethodSpecs::Methods.new).call
+  it "preserves frozen status" do
+    method = Class.instance_method(:instance_method)
+    method.freeze
+    method.frozen?.should == true
+    method.clone.frozen?.should == true
   end
 end
diff --git a/spec/ruby/core/unboundmethod/dup_spec.rb b/spec/ruby/core/unboundmethod/dup_spec.rb
new file mode 100644
index 0000000000..5a78dd8e36
--- /dev/null
+++ b/spec/ruby/core/unboundmethod/dup_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+require_relative 'shared/dup'
+
+describe "UnboundMethod#dup" do
+  ruby_version_is "3.4" do
+    it_behaves_like :unboundmethod_dup, :dup
+
+    it "resets frozen status" do
+      method = Class.instance_method(:instance_method)
+      method.freeze
+      method.frozen?.should == true
+      method.dup.frozen?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/core/unboundmethod/equal_value_spec.rb b/spec/ruby/core/unboundmethod/equal_value_spec.rb
index 6242b04884..24d5233299 100644
--- a/spec/ruby/core/unboundmethod/equal_value_spec.rb
+++ b/spec/ruby/core/unboundmethod/equal_value_spec.rb
@@ -3,8 +3,8 @@ require_relative 'fixtures/classes'
 
 context "Creating UnboundMethods" do
   specify "there is no difference between Method#unbind and Module#instance_method" do
-    UnboundMethodSpecs::Methods.instance_method(:foo).should be_kind_of(UnboundMethod)
-    UnboundMethodSpecs::Methods.new.method(:foo).unbind.should be_kind_of(UnboundMethod)
+    UnboundMethodSpecs::Methods.instance_method(:foo).should.is_a?(UnboundMethod)
+    UnboundMethodSpecs::Methods.new.method(:foo).unbind.should.is_a?(UnboundMethod)
   end
 end
 
@@ -35,6 +35,12 @@ describe "UnboundMethod#==" do
 
     @method_one = UnboundMethodSpecs::Methods.instance_method(:one)
     @method_two = UnboundMethodSpecs::Methods.instance_method(:two)
+
+    @mixin = UnboundMethodSpecs::Mixin.instance_method(:mixin_method)
+    @includer_base = UnboundMethodSpecs::IncluderBase.new.method(:mixin_method).unbind
+    @includer_child = UnboundMethodSpecs::IncluderChild.new.method(:mixin_method).unbind
+    @extender_base = UnboundMethodSpecs::ExtenderBase.method(:mixin_method).unbind
+    @extender_child = UnboundMethodSpecs::ExtenderChild.method(:mixin_method).unbind
   end
 
   it "returns true if objects refer to the same method" do
@@ -76,19 +82,43 @@ describe "UnboundMethod#==" do
     (@identical_body == @original_body).should == false
   end
 
-  it "returns false if same method but one extracted from a subclass" do
-    (@parent == @child1).should == false
-    (@child1 == @parent).should == false
+  it "returns true if same method but one extracted from a subclass" do
+    (@parent == @child1).should == true
+    (@child1 == @parent).should == true
   end
 
-  it "returns false if same method but extracted from two different subclasses" do
-    (@child2 == @child1).should == false
-    (@child1 == @child2).should == false
+  it "returns true if same method but extracted from two different subclasses" do
+    (@child2 == @child1).should == true
+    (@child1 == @child2).should == true
   end
 
-  it "returns false if methods are the same but added from an included Module" do
-    (@includee == @includer).should == false
-    (@includer == @includee).should == false
+  it "returns true if methods are the same but added from an included Module" do
+    (@includee == @includer).should == true
+    (@includer == @includee).should == true
+  end
+
+  ruby_bug "#21873", ""..."4.1" do
+    it "returns true if same method is present in an object through module inclusion" do
+      (@mixin == @includer_base).should == true
+      (@includer_base == @mixin).should == true
+
+      (@mixin == @includer_child).should == true
+      (@includer_child == @mixin).should == true
+
+      (@includer_base == @includer_child).should == true
+      (@includer_child == @includer_base).should == true
+    end
+
+    it "returns true if same method is present in an object through module extension" do
+      (@mixin == @extender_base).should == true
+      (@extender_base == @mixin).should == true
+
+      (@mixin == @extender_child).should == true
+      (@extender_child == @mixin).should == true
+
+      (@extender_base == @extender_child).should == true
+      (@extender_child == @extender_base).should == true
+    end
   end
 
   it "returns false if both have same Module, same name, identical body but not the same" do
@@ -98,4 +128,38 @@ describe "UnboundMethod#==" do
 
     (@discard_1 == UnboundMethodSpecs::Methods.instance_method(:discard_1)).should == false
   end
+
+  it "considers methods through aliasing equal" do
+    c = Class.new do
+      class << self
+        alias_method :n, :new
+      end
+    end
+
+    c.method(:new).should == c.method(:n)
+    c.method(:n).should == Class.instance_method(:new).bind(c)
+  end
+
+  it "considers methods through visibility change equal" do
+    c = Class.new do
+      class << self
+        private :new
+      end
+    end
+
+    c.method(:new).should == Class.instance_method(:new).bind(c)
+  end
+
+  it "considers methods through aliasing and visibility change equal" do
+    c = Class.new do
+      class << self
+        alias_method :n, :new
+        private :new
+      end
+    end
+
+    c.method(:new).should == c.method(:n)
+    c.method(:n).should == Class.instance_method(:new).bind(c)
+    c.method(:new).should == Class.instance_method(:new).bind(c)
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/fixtures/classes.rb b/spec/ruby/core/unboundmethod/fixtures/classes.rb
index 46b1c51669..58120c2f88 100644
--- a/spec/ruby/core/unboundmethod/fixtures/classes.rb
+++ b/spec/ruby/core/unboundmethod/fixtures/classes.rb
@@ -22,6 +22,7 @@ module UnboundMethodSpecs
 
   module Mod
     def from_mod; end
+    def foo_super; super; end
   end
 
   class Methods
@@ -35,6 +36,7 @@ module UnboundMethodSpecs
 
     alias bar foo
     alias baz bar
+    alias qux baz
     alias alias_1 foo
     alias alias_2 foo
 
@@ -53,10 +55,19 @@ module UnboundMethodSpecs
 
     def discard_1(); :discard; end
     def discard_2(); :discard; end
+
+    def my_public_method; end
+    def my_protected_method; end
+    def my_private_method; end
+    protected :my_protected_method
+    private :my_private_method
   end
 
   class Parent
     def foo; end
+    def foo_super
+      true
+    end
     def self.class_method
       "I am #{name}"
     end
@@ -70,6 +81,22 @@ module UnboundMethodSpecs
     end
   end
 
+  module Mixin
+    def mixin_method; end
+  end
+
+  class IncluderBase
+    include Mixin
+  end
+
+  class IncluderChild < IncluderBase; end
+
+  class ExtenderBase
+    extend Mixin
+  end
+
+  class ExtenderChild < ExtenderBase; end
+
   class A
     def baz(a, b)
       return [__FILE__, self.class]
@@ -84,4 +111,14 @@ module UnboundMethodSpecs
   class C < B
     def overridden; end
   end
+
+  module HashSpecs
+    class SuperClass
+      def foo
+      end
+    end
+
+    class SubClass < SuperClass
+    end
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/hash_spec.rb b/spec/ruby/core/unboundmethod/hash_spec.rb
index 12dce0020f..6888675bc1 100644
--- a/spec/ruby/core/unboundmethod/hash_spec.rb
+++ b/spec/ruby/core/unboundmethod/hash_spec.rb
@@ -12,4 +12,11 @@ describe "UnboundMethod#hash" do
     to_s, inspect = Array.instance_method(:to_s), Array.instance_method(:inspect)
     to_s.hash.should == inspect.hash
   end
+
+  it "equals a hash of the same method in the superclass" do
+    foo_in_superclass = UnboundMethodSpecs::HashSpecs::SuperClass.instance_method(:foo)
+    foo = UnboundMethodSpecs::HashSpecs::SubClass.instance_method(:foo)
+
+    foo.hash.should == foo_in_superclass.hash
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/inspect_spec.rb b/spec/ruby/core/unboundmethod/inspect_spec.rb
index cecf542fcd..3abed94f7f 100644
--- a/spec/ruby/core/unboundmethod/inspect_spec.rb
+++ b/spec/ruby/core/unboundmethod/inspect_spec.rb
@@ -1,7 +1,9 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/to_s'
+require_relative '../method/shared/aliased_inspect'
 
 describe "UnboundMethod#inspect" do
   it_behaves_like :unboundmethod_to_s, :inspect
+  it_behaves_like :method_to_s_aliased, :inspect, -> meth { meth.unbind }
 end
diff --git a/spec/ruby/core/unboundmethod/original_name_spec.rb b/spec/ruby/core/unboundmethod/original_name_spec.rb
index 7280dcb2b4..cd5f55805d 100644
--- a/spec/ruby/core/unboundmethod/original_name_spec.rb
+++ b/spec/ruby/core/unboundmethod/original_name_spec.rb
@@ -19,4 +19,41 @@ describe "UnboundMethod#original_name" do
     obj.method(:baz).unbind.original_name.should == :foo
     UnboundMethodSpecs::Methods.instance_method(:baz).original_name.should == :foo
   end
+
+  it "returns the original name even when aliased thrice" do
+    obj = UnboundMethodSpecs::Methods.new
+    obj.method(:qux).unbind.original_name.should == :foo
+    UnboundMethodSpecs::Methods.instance_method(:qux).original_name.should == :foo
+  end
+
+  it "returns the source UnboundMethod's name (not the name given to define_method)" do
+    klass = Class.new { define_method(:my_inspect, ::Kernel.instance_method(:inspect)) }
+    klass.instance_method(:my_inspect).original_name.should == :inspect
+  end
+
+  it "preserves the source method's name through define_method and alias" do
+    source = Class.new { def my_method; end }
+    klass = Class.new(source) do
+      define_method(:renamed, source.instance_method(:my_method))
+      alias aliased renamed
+    end
+    klass.instance_method(:renamed).original_name.should == :my_method
+    klass.instance_method(:aliased).original_name.should == :my_method
+  end
+
+  it "returns the source UnboundMethod's name for Kernel#is_a? and Kernel#kind_of?" do
+    klass = Class.new { define_method(:my_is_a?, ::Kernel.instance_method(:is_a?)) }
+    klass.instance_method(:my_is_a?).original_name.should == :is_a?
+
+    klass = Class.new { define_method(:my_kind_of?, ::Kernel.instance_method(:kind_of?)) }
+    klass.instance_method(:my_kind_of?).original_name.should == :kind_of?
+  end
+
+  it "preserves the source name when aliasing a define_method'd Kernel method" do
+    klass = Class.new do
+      define_method(:my_is_a?, ::Kernel.instance_method(:is_a?))
+      alias_method :renamed_is_a?, :my_is_a?
+    end
+    klass.instance_method(:renamed_is_a?).original_name.should == :is_a?
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/owner_spec.rb b/spec/ruby/core/unboundmethod/owner_spec.rb
index 5f1f4646b3..b099c56de1 100644
--- a/spec/ruby/core/unboundmethod/owner_spec.rb
+++ b/spec/ruby/core/unboundmethod/owner_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../method/fixtures/classes'
 
 describe "UnboundMethod#owner" do
   it "returns the owner of the method" do
@@ -23,4 +24,8 @@ describe "UnboundMethod#owner" do
     child_singleton_class.instance_method(:class_method).owner.should == parent_singleton_class
     child_singleton_class.instance_method(:another_class_method).owner.should == child_singleton_class
   end
+
+  it "returns the class on which public was called for a private method in ancestor" do
+    MethodSpecs::InheritedMethods::C.instance_method(:derp).owner.should == MethodSpecs::InheritedMethods::C
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/private_spec.rb b/spec/ruby/core/unboundmethod/private_spec.rb
new file mode 100644
index 0000000000..5a563939d1
--- /dev/null
+++ b/spec/ruby/core/unboundmethod/private_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "UnboundMethod#private?" do
+  it "has been removed" do
+    obj = UnboundMethodSpecs::Methods.new
+    obj.method(:my_private_method).unbind.should_not.respond_to?(:private?)
+  end
+end
diff --git a/spec/ruby/core/unboundmethod/protected_spec.rb b/spec/ruby/core/unboundmethod/protected_spec.rb
new file mode 100644
index 0000000000..70622d658d
--- /dev/null
+++ b/spec/ruby/core/unboundmethod/protected_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "UnboundMethod#protected?" do
+  it "has been removed" do
+    obj = UnboundMethodSpecs::Methods.new
+    obj.method(:my_protected_method).unbind.should_not.respond_to?(:protected?)
+  end
+end
diff --git a/spec/ruby/core/unboundmethod/public_spec.rb b/spec/ruby/core/unboundmethod/public_spec.rb
new file mode 100644
index 0000000000..ae75e2601c
--- /dev/null
+++ b/spec/ruby/core/unboundmethod/public_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "UnboundMethod#public?" do
+  it "has been removed" do
+    obj = UnboundMethodSpecs::Methods.new
+    obj.method(:my_public_method).unbind.should_not.respond_to?(:public?)
+  end
+end
diff --git a/spec/ruby/core/unboundmethod/shared/dup.rb b/spec/ruby/core/unboundmethod/shared/dup.rb
new file mode 100644
index 0000000000..fd30f75c5b
--- /dev/null
+++ b/spec/ruby/core/unboundmethod/shared/dup.rb
@@ -0,0 +1,32 @@
+describe :unboundmethod_dup, shared: true do
+  it "returns a copy of self" do
+    a = Class.instance_method(:instance_method)
+    b = a.send(@method)
+
+    a.should == b
+    a.should_not.equal?(b)
+  end
+
+  ruby_version_is "3.4" do
+    it "copies instance variables" do
+      method = Class.instance_method(:instance_method)
+      method.instance_variable_set(:@ivar, 1)
+      cl = method.send(@method)
+      cl.instance_variables.should == [:@ivar]
+    end
+
+    it "copies the finalizer" do
+      code = <<-'RUBY'
+        obj = Class.instance_method(:instance_method)
+
+        ObjectSpace.define_finalizer(obj, Proc.new { STDOUT.write "finalized\n" })
+
+        obj.clone
+
+        exit 0
+      RUBY
+
+      ruby_exe(code).lines.sort.should == ["finalized\n", "finalized\n"]
+    end
+  end
+end
diff --git a/spec/ruby/core/unboundmethod/shared/to_s.rb b/spec/ruby/core/unboundmethod/shared/to_s.rb
index 3987611d3f..848c1eba2e 100644
--- a/spec/ruby/core/unboundmethod/shared/to_s.rb
+++ b/spec/ruby/core/unboundmethod/shared/to_s.rb
@@ -8,8 +8,8 @@ describe :unboundmethod_to_s, shared: true do
   end
 
   it "returns a String" do
-    @from_module.send(@method).should be_kind_of(String)
-    @from_method.send(@method).should be_kind_of(String)
+    @from_module.send(@method).should.is_a?(String)
+    @from_method.send(@method).should.is_a?(String)
   end
 
   it "the String reflects that this is an UnboundMethod object" do
@@ -20,6 +20,14 @@ describe :unboundmethod_to_s, shared: true do
   it "the String shows the method name, Module defined in and Module extracted from" do
     @from_module.send(@method).should =~ /\bfrom_mod\b/
     @from_module.send(@method).should =~ /\bUnboundMethodSpecs::Mod\b/
-    @from_method.send(@method).should =~ /\bUnboundMethodSpecs::Methods\b/
+  end
+
+  it "returns a String including all details" do
+    @from_module.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Mod#from_mod"
+    @from_method.send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::Mod#from_mod"
+  end
+
+  it "does not show the defining module if it is the same as the origin" do
+    UnboundMethodSpecs::A.instance_method(:baz).send(@method).should.start_with? "#<UnboundMethod: UnboundMethodSpecs::A#baz"
   end
 end
diff --git a/spec/ruby/core/unboundmethod/source_location_spec.rb b/spec/ruby/core/unboundmethod/source_location_spec.rb
index b5e6413816..927600bfcb 100644
--- a/spec/ruby/core/unboundmethod/source_location_spec.rb
+++ b/spec/ruby/core/unboundmethod/source_location_spec.rb
@@ -8,13 +8,13 @@ describe "UnboundMethod#source_location" do
 
   it "sets the first value to the path of the file in which the method was defined" do
     file = @method.source_location.first
-    file.should be_an_instance_of(String)
-    file.should == File.realpath('../fixtures/classes.rb', __FILE__)
+    file.should.instance_of?(String)
+    file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
-  it "sets the last value to a Fixnum representing the line on which the method was defined" do
+  it "sets the last value to an Integer representing the line on which the method was defined" do
     line = @method.source_location.last
-    line.should be_an_instance_of(Fixnum)
+    line.should.instance_of?(Integer)
     line.should == 5
   end
 
@@ -49,4 +49,11 @@ describe "UnboundMethod#source_location" do
     method.source_location[0].should =~ /#{__FILE__}/
     method.source_location[1].should == line
   end
+
+  it "works for eval with a given line" do
+    c = Class.new do
+      eval('def m; end', nil, "foo", 100)
+    end
+    c.instance_method(:m).source_location.should == ["foo", 100]
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/super_method_spec.rb b/spec/ruby/core/unboundmethod/super_method_spec.rb
index c9fa1ec533..aa7c129377 100644
--- a/spec/ruby/core/unboundmethod/super_method_spec.rb
+++ b/spec/ruby/core/unboundmethod/super_method_spec.rb
@@ -1,5 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../method/fixtures/classes'
 
 describe "UnboundMethod#super_method" do
   it "returns the method that would be called by super in the method" do
@@ -25,4 +26,24 @@ describe "UnboundMethod#super_method" do
 
     method.super_method.should == nil
   end
+
+  # https://github.com/jruby/jruby/issues/7240
+  context "after changing an inherited methods visibility" do
+    it "calls the proper super method" do
+      method = MethodSpecs::InheritedMethods::C.instance_method(:derp)
+      method.bind(MethodSpecs::InheritedMethods::C.new).call.should == 'BA'
+    end
+
+    it "returns the expected super_method" do
+      method = MethodSpecs::InheritedMethods::C.instance_method(:derp)
+      method.super_method.owner.should == MethodSpecs::InheritedMethods::A
+    end
+  end
+
+  context "after aliasing an inherited method" do
+    it "returns the expected super_method" do
+      method = MethodSpecs::InheritedMethods::C.instance_method(:meow)
+      method.super_method.owner.should == MethodSpecs::InheritedMethods::A
+    end
+  end
 end
diff --git a/spec/ruby/core/unboundmethod/to_s_spec.rb b/spec/ruby/core/unboundmethod/to_s_spec.rb
index a508229b49..615d88675b 100644
--- a/spec/ruby/core/unboundmethod/to_s_spec.rb
+++ b/spec/ruby/core/unboundmethod/to_s_spec.rb
@@ -1,7 +1,9 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/to_s'
+require_relative '../method/shared/aliased_inspect'
 
 describe "UnboundMethod#to_s" do
   it_behaves_like :unboundmethod_to_s, :to_s
+  it_behaves_like :method_to_s_aliased, :to_s, -> meth { meth.unbind }
 end
diff --git a/spec/ruby/core/warning/categories_spec.rb b/spec/ruby/core/warning/categories_spec.rb
new file mode 100644
index 0000000000..1e310ef38b
--- /dev/null
+++ b/spec/ruby/core/warning/categories_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "3.4" do
+  describe "Warning.categories" do
+    # There might be more, but these are standard across Ruby implementations
+    it "returns the list of possible warning categories" do
+      Warning.categories.should.include? :deprecated
+      Warning.categories.should.include? :experimental
+      Warning.categories.should.include? :performance
+    end
+  end
+end
diff --git a/spec/ruby/core/warning/element_reference_spec.rb b/spec/ruby/core/warning/element_reference_spec.rb
new file mode 100644
index 0000000000..5f977759ec
--- /dev/null
+++ b/spec/ruby/core/warning/element_reference_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../spec_helper'
+
+describe "Warning.[]" do
+  it "returns default values for categories :deprecated and :experimental" do
+    # If any warning options were set on the Ruby that will be executed, then
+    # it's possible this test will fail. In this case we will skip this test.
+    skip if ruby_exe.any? { |opt| opt.start_with?("-W") }
+
+    ruby_exe('p [Warning[:deprecated], Warning[:experimental]]').chomp.should == "[false, true]"
+    ruby_exe('p [Warning[:deprecated], Warning[:experimental]]', options: "-w").chomp.should == "[true, true]"
+  end
+
+  it "returns default values for :performance category" do
+    ruby_exe('p Warning[:performance]').chomp.should == "false"
+    ruby_exe('p Warning[:performance]', options: "-w").chomp.should == "false"
+  end
+
+  it "raises for unknown category" do
+    -> { Warning[:noop] }.should.raise(ArgumentError, /unknown category: noop/)
+  end
+
+  it "raises for non-Symbol category" do
+    -> { Warning[42] }.should.raise(TypeError)
+    -> { Warning[false] }.should.raise(TypeError)
+    -> { Warning["noop"] }.should.raise(TypeError)
+  end
+end
diff --git a/spec/ruby/core/warning/element_set_spec.rb b/spec/ruby/core/warning/element_set_spec.rb
new file mode 100644
index 0000000000..3c8ceb721e
--- /dev/null
+++ b/spec/ruby/core/warning/element_set_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../spec_helper'
+
+describe "Warning.[]=" do
+  it "emits and suppresses warnings for :deprecated" do
+    ruby_exe('Warning[:deprecated] = true; $; = ""', args: "2>&1").should =~ /is deprecated/
+    ruby_exe('Warning[:deprecated] = false; $; = ""', args: "2>&1").should == ""
+  end
+
+  describe ":experimental" do
+    before do
+      @src = 'warn "This is experimental warning.", category: :experimental'
+    end
+
+    it "emits and suppresses warnings for :experimental" do
+      ruby_exe("Warning[:experimental] = true; eval('#{@src}')", args: "2>&1").should =~ /is experimental/
+      ruby_exe("Warning[:experimental] = false; eval('#{@src}')", args: "2>&1").should == ""
+    end
+  end
+
+  it "enables or disables performance warnings" do
+    original = Warning[:performance]
+    begin
+      Warning[:performance] = !original
+      Warning[:performance].should == !original
+    ensure
+      Warning[:performance] = original
+    end
+  end
+
+  it "raises for unknown category" do
+    -> { Warning[:noop] = false }.should.raise(ArgumentError, /unknown category: noop/)
+  end
+
+  it "raises for non-Symbol category" do
+    -> { Warning[42] = false }.should.raise(TypeError)
+    -> { Warning[false] = false }.should.raise(TypeError)
+    -> { Warning["noop"] = false }.should.raise(TypeError)
+  end
+end
diff --git a/spec/ruby/core/warning/performance_warning_spec.rb b/spec/ruby/core/warning/performance_warning_spec.rb
new file mode 100644
index 0000000000..ab0badcd3d
--- /dev/null
+++ b/spec/ruby/core/warning/performance_warning_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+
+
+describe "Performance warnings" do
+  guard -> { ruby_version_is("3.4") || RUBY_ENGINE == "truffleruby" } do
+    # Optimising Integer, Float or Symbol methods is kind of implementation detail
+    # but multiple implementations do so. So it seems reasonable to have a test case
+    # for at least one such common method.
+    # See https://bugs.ruby-lang.org/issues/20429
+    context "when redefined optimised methods" do
+      it "emits performance warning for redefining Integer#+" do
+        code = <<~CODE
+          Warning[:performance] = true
+
+          class Integer
+            ORIG_METHOD = instance_method(:+)
+
+            def +(...)
+              ORIG_METHOD.bind(self).call(...)
+            end
+          end
+        CODE
+
+        ruby_exe(code, args: "2>&1").should.include?("warning: Redefining 'Integer#+' disables interpreter and JIT optimizations")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/warning/warn_spec.rb b/spec/ruby/core/warning/warn_spec.rb
index 7daf6323c3..62f36e3454 100644
--- a/spec/ruby/core/warning/warn_spec.rb
+++ b/spec/ruby/core/warning/warn_spec.rb
@@ -16,7 +16,7 @@ describe "Warning.warn" do
   end
 
   it "extends itself" do
-    Warning.singleton_class.ancestors.should include(Warning)
+    Warning.singleton_class.ancestors.should.include?(Warning)
   end
 
   it "has Warning as the method owner" do
@@ -51,16 +51,137 @@ describe "Warning.warn" do
     end
   end
 
-  ruby_version_is "2.5" do
-    it "is called by Kernel.warn" do
-      Warning.should_receive(:warn).with("Chunky bacon!\n")
-      verbose = $VERBOSE
-      $VERBOSE = false
+  it "is called by Kernel.warn with nil category keyword" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: nil)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!")
+    ensure
+      $VERBOSE = verbose
+    end
+  end
+
+  it "is called by Kernel.warn with given category keyword converted to a symbol" do
+    Warning.should_receive(:warn).with("Chunky bacon!\n", category: :deprecated)
+    verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      Kernel.warn("Chunky bacon!", category: "deprecated")
+    ensure
+      $VERBOSE = verbose
+    end
+  end
+
+  it "warns when category is :deprecated and Warning[:deprecated] is true" do
+    warn_deprecated = Warning[:deprecated]
+    Warning[:deprecated] = true
+    begin
+      -> {
+        Warning.warn("foo", category: :deprecated)
+      }.should complain("foo")
+    ensure
+      Warning[:deprecated] = warn_deprecated
+    end
+  end
+
+  it "warns when category is :experimental and Warning[:experimental] is true" do
+    warn_experimental = Warning[:experimental]
+    Warning[:experimental] = true
+    begin
+      -> {
+        Warning.warn("foo", category: :experimental)
+      }.should complain("foo")
+    ensure
+      Warning[:experimental] = warn_experimental
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "warns when category is :strict_unused_block but Warning[:strict_unused_block] is false" do
+      warn_strict_unused_block = Warning[:strict_unused_block]
+      Warning[:strict_unused_block] = true
       begin
-        Kernel.warn("Chunky bacon!")
+        -> {
+          Warning.warn("foo", category: :strict_unused_block)
+        }.should complain("foo")
       ensure
-        $VERBOSE = verbose
+        Warning[:strict_unused_block] = warn_strict_unused_block
       end
     end
   end
+
+  it "doesn't print message when category is :deprecated but Warning[:deprecated] is false" do
+    warn_deprecated = Warning[:deprecated]
+    Warning[:deprecated] = false
+    begin
+      -> {
+        Warning.warn("foo", category: :deprecated)
+      }.should_not complain
+    ensure
+      Warning[:deprecated] = warn_deprecated
+    end
+  end
+
+  it "doesn't print message when category is :experimental but Warning[:experimental] is false" do
+    warn_experimental = Warning[:experimental]
+    Warning[:experimental] = false
+    begin
+      -> {
+        Warning.warn("foo", category: :experimental)
+      }.should_not complain
+    ensure
+      Warning[:experimental] = warn_experimental
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "doesn't print message when category is :strict_unused_block but Warning[:strict_unused_block] is false" do
+      warn_strict_unused_block = Warning[:strict_unused_block]
+      Warning[:strict_unused_block] = false
+      begin
+        -> {
+          Warning.warn("foo", category: :strict_unused_block)
+        }.should_not complain
+      ensure
+        Warning[:strict_unused_block] = warn_strict_unused_block
+      end
+    end
+  end
+
+  ruby_bug '#20573', ''...'3.4' do
+    it "isn't called by Kernel.warn when category is :deprecated but Warning[:deprecated] is false" do
+      warn_deprecated = Warning[:deprecated]
+      begin
+        Warning[:deprecated] = false
+        Warning.should_not_receive(:warn)
+        Kernel.warn("foo", category: :deprecated)
+      ensure
+        Warning[:deprecated] = warn_deprecated
+      end
+    end
+
+    it "isn't called by Kernel.warn when category is :experimental but Warning[:experimental] is false" do
+      warn_experimental = Warning[:experimental]
+      begin
+        Warning[:experimental] = false
+        Warning.should_not_receive(:warn)
+        Kernel.warn("foo", category: :experimental)
+      ensure
+        Warning[:experimental] = warn_experimental
+      end
+    end
+  end
+
+  it "prints the message when VERBOSE is false" do
+    -> { Warning.warn("foo") }.should complain("foo")
+  end
+
+  it "prints the message when VERBOSE is nil" do
+    -> { Warning.warn("foo") }.should complain("foo", verbose: nil)
+  end
+
+  it "prints the message when VERBOSE is true" do
+    -> { Warning.warn("foo") }.should complain("foo", verbose: true)
+  end
 end
diff --git a/spec/ruby/default.mspec b/spec/ruby/default.mspec
index 6fd6d2bf9c..c8b1215f56 100644
--- a/spec/ruby/default.mspec
+++ b/spec/ruby/default.mspec
@@ -1,3 +1,4 @@
+# -*- ruby -*-
 # Configuration file for Ruby >= 2.0 implementations.
 
 class MSpecScript
@@ -19,8 +20,11 @@ class MSpecScript
   # C extension API specs
   set :capi, [ 'optional/capi' ]
 
+  # Thread safety specs
+  set :thread_safety, [ 'optional/thread_safety' ]
+
   # A list of _all_ optional specs
-  set :optional, get(:capi)
+  set :optional, get(:capi) + get(:thread_safety)
 
   # An ordered list of the directories containing specs to run
   set :files, get(:command_line) + get(:language) + get(:core) + get(:library) + get(:security) + get(:optional)
@@ -45,5 +49,6 @@ class MSpecScript
   set :toplevel_constants_excludes, [
     /\wSpecs?$/,
     /^CS_CONST/,
+    /^CSL_CONST/,
   ]
 end
diff --git a/spec/ruby/fixtures/class.rb b/spec/ruby/fixtures/class.rb
index 68fbca7ba7..98cb6c82a2 100644
--- a/spec/ruby/fixtures/class.rb
+++ b/spec/ruby/fixtures/class.rb
@@ -122,6 +122,10 @@ module ClassSpecs
       end
     end
   end
+
+  DEFINE_CLASS = -> do
+    class ::A; end
+  end
 end
 
 class Class
diff --git a/spec/ruby/fixtures/code/a/load_fixture.dylib b/spec/ruby/fixtures/code/a/load_fixture.dylib
new file mode 100644
index 0000000000..31f4b1a7bb
--- /dev/null
+++ b/spec/ruby/fixtures/code/a/load_fixture.dylib
@@ -0,0 +1 @@
+ScratchPad << :ext_dylib
diff --git a/spec/ruby/fixtures/code/c/load_fixture.rb b/spec/ruby/fixtures/code/c/load_fixture.rb
new file mode 100644
index 0000000000..4a6e9c9601
--- /dev/null
+++ b/spec/ruby/fixtures/code/c/load_fixture.rb
@@ -0,0 +1 @@
+ScratchPad << :loaded
diff --git a/spec/ruby/fixtures/code/concurrent.rb b/spec/ruby/fixtures/code/concurrent.rb
index 054b8fc055..b3602a3db4 100644
--- a/spec/ruby/fixtures/code/concurrent.rb
+++ b/spec/ruby/fixtures/code/concurrent.rb
@@ -2,7 +2,7 @@ ScratchPad.recorded << :con_pre
 Thread.current[:in_concurrent_rb] = true
 
 if t = Thread.current[:wait_for]
-  Thread.pass until t.backtrace && t.backtrace.any? { |call| call.include? 'require' }
+  Thread.pass until t.backtrace && t.backtrace.any? { |call| call.include? 'require' } && t.stop?
 end
 
 if Thread.current[:con_raise]
diff --git a/spec/ruby/fixtures/code/concurrent_require_fixture.rb b/spec/ruby/fixtures/code/concurrent_require_fixture.rb
new file mode 100644
index 0000000000..d4ce734183
--- /dev/null
+++ b/spec/ruby/fixtures/code/concurrent_require_fixture.rb
@@ -0,0 +1,4 @@
+object = ScratchPad.recorded
+thread = Thread.new { object.require(__FILE__) }
+Thread.pass until thread.stop?
+ScratchPad.record(thread)
diff --git a/spec/ruby/fixtures/code/d/load_fixture.rb.rb b/spec/ruby/fixtures/code/d/load_fixture.rb.rb
new file mode 100644
index 0000000000..7e9217729a
--- /dev/null
+++ b/spec/ruby/fixtures/code/d/load_fixture.rb.rb
@@ -0,0 +1 @@
+ScratchPad << :rbrb
diff --git a/spec/ruby/fixtures/code/load_fixture.dylib b/spec/ruby/fixtures/code/load_fixture.dylib
new file mode 100644
index 0000000000..31f4b1a7bb
--- /dev/null
+++ b/spec/ruby/fixtures/code/load_fixture.dylib
@@ -0,0 +1 @@
+ScratchPad << :ext_dylib
diff --git a/spec/ruby/fixtures/code/load_fixture.ext.dylib b/spec/ruby/fixtures/code/load_fixture.ext.dylib
new file mode 100644
index 0000000000..31f4b1a7bb
--- /dev/null
+++ b/spec/ruby/fixtures/code/load_fixture.ext.dylib
@@ -0,0 +1 @@
+ScratchPad << :ext_dylib
diff --git a/spec/ruby/fixtures/code/load_wrap_fixture.rb b/spec/ruby/fixtures/code/load_wrap_fixture.rb
new file mode 100644
index 0000000000..526bbf8c82
--- /dev/null
+++ b/spec/ruby/fixtures/code/load_wrap_fixture.rb
@@ -0,0 +1,12 @@
+class LoadSpecWrap
+  ScratchPad << String
+end
+
+LOAD_WRAP_SPECS_TOP_LEVEL_CONSTANT = 1
+
+def load_wrap_specs_top_level_method
+  :load_wrap_specs_top_level_method
+end
+ScratchPad << method(:load_wrap_specs_top_level_method).owner
+
+ScratchPad << self
diff --git a/spec/ruby/fixtures/code/wrap_fixture.rb b/spec/ruby/fixtures/code/wrap_fixture.rb
deleted file mode 100644
index b83a8970d7..0000000000
--- a/spec/ruby/fixtures/code/wrap_fixture.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-class LoadSpecWrap
-  ScratchPad << self
-end
diff --git a/spec/ruby/fixtures/code_loading.rb b/spec/ruby/fixtures/code_loading.rb
index d6cf0edb47..decd56a358 100644
--- a/spec/ruby/fixtures/code_loading.rb
+++ b/spec/ruby/fixtures/code_loading.rb
@@ -12,7 +12,22 @@ module CodeLoadingSpecs
     end
   end
 
+  def self.preload_rubygems
+    # Require RubyGems eagerly, to ensure #require is already the RubyGems
+    # version and RubyGems is only loaded once, before starting #require/#autoload specs
+    # which snapshot $LOADED_FEATURES and could cause RubyGems to load twice.
+    # #require specs also snapshot #require, and could end up redefining #require as the original core Kernel#require.
+    @rubygems ||= begin
+      require "rubygems"
+      true
+    rescue LoadError
+      true
+    end
+  end
+
   def self.spec_setup
+    preload_rubygems
+
     @saved_loaded_features = $LOADED_FEATURES.clone
     @saved_load_path = $LOAD_PATH.clone
     ScratchPad.record []
diff --git a/spec/ruby/fixtures/constants.rb b/spec/ruby/fixtures/constants.rb
index e5b20596ef..7f0b88daab 100644
--- a/spec/ruby/fixtures/constants.rb
+++ b/spec/ruby/fixtures/constants.rb
@@ -1,7 +1,7 @@
 # Contains all static code examples of all constants behavior in language and
 # library specs. The specs include language/constants_spec.rb and the specs
-# for Module#const_defined?, Module#const_get, Module#const_set,
-# Module#remove_const, Module#const_missing and Module#constants.
+# for Module#const_defined?, Module#const_get, Module#const_set, Module#remove_const,
+# Module#const_source_location, Module#const_missing and Module#constants.
 #
 # Rather than defining a class structure for each example, a canonical set of
 # classes is used along with numerous constants, in most cases, a unique
@@ -10,7 +10,7 @@
 # variety in class and module configurations, including hierarchy,
 # containment, inclusion, singletons and toplevel.
 #
-# Constants are numbered for for uniqueness. The CS_ prefix is uniformly used
+# Constants are numbered for uniqueness. The CS_ prefix is uniformly used
 # and is to minimize clashes with other toplevel constants (see e.g. ModuleA
 # which is included in Object). Constant values are symbols. A numbered suffix
 # is used to distinguish constants with the same name defined in different
@@ -28,28 +28,34 @@
 # for completeness. No other constant of this name should be defined in the
 # specs.
 CS_CONST1 = :const1   # only defined here
+CS_CONST1_LINE = __LINE__ - 1
 
 module ConstantSpecs
 
   # Included at toplevel
   module ModuleA
     CS_CONST10 = :const10_1
+    CS_CONST10_LINE = __LINE__ - 1
     CS_CONST12 = :const12_2
     CS_CONST13 = :const13
+    CS_CONST13_LINE = __LINE__ - 1
     CS_CONST21 = :const21_2
   end
 
   # Included in ParentA
   module ModuleB
+    LINE = __LINE__ - 1
     CS_CONST10 = :const10_9
     CS_CONST11 = :const11_2
     CS_CONST12 = :const12_1
+    CS_CONST12_LINE = __LINE__ - 1
   end
 
   # Included in ChildA
   module ModuleC
     CS_CONST10 = :const10_4
     CS_CONST15 = :const15_1
+    CS_CONST15_LINE = __LINE__ - 1
   end
 
   # Included in ChildA metaclass
@@ -70,12 +76,21 @@ module ConstantSpecs
     CS_CONST10 = :const10_8
   end
 
+  # Included in ContainerA
+  module ModuleIncludePrepended
+    prepend ModuleD
+
+    CS_CONST11 = :const11_8
+  end
+
   # The following classes/modules have all the constants set "statically".
   # Contrast with the classes below where the constants are set as the specs
   # are run.
 
   class ClassA
+    LINE = __LINE__ - 1
     CS_CONST10 = :const10_10
+    CS_CONST10_LINE = __LINE__ - 1
     CS_CONST16 = :const16
     CS_CONST17 = :const17_2
     CS_CONST22 = :const22_1
@@ -97,10 +112,14 @@ module ConstantSpecs
     include ModuleB
 
     CS_CONST4 = :const4
+    CS_CONST4_LINE = __LINE__ - 1
     CS_CONST10 = :const10_5
+    CS_CONST10_LINE = __LINE__ - 1
     CS_CONST11 = :const11_1
+    CS_CONST11_LINE = __LINE__ - 1
     CS_CONST15 = :const15_2
     CS_CONST20 = :const20_2
+    CS_CONST20_LINE = __LINE__ - 1
     CS_CONST21 = :const21_1
     CS_CONST22 = :const22_2
 
@@ -118,6 +137,7 @@ module ConstantSpecs
 
     CS_CONST5 = :const5
     CS_CONST10 = :const10_2
+    CS_CONST10_LINE = __LINE__ - 1
     CS_CONST23 = :const23
 
     class ChildA < ParentA
@@ -135,6 +155,7 @@ module ConstantSpecs
 
       CS_CONST6 = :const6
       CS_CONST10 = :const10_3
+      CS_CONST10_LINE = __LINE__ - 1
       CS_CONST19 = :const19_2
 
       def self.const10; CS_CONST10; end
@@ -156,6 +177,10 @@ module ConstantSpecs
     def const10; CS_CONST10; end
   end
 
+  class ContainerPrepend
+    include ModuleIncludePrepended
+  end
+
   class ContainerA::ChildA
     def self.const23; CS_CONST23; end
   end
@@ -282,7 +307,18 @@ module ConstantSpecs
   end
 
   CS_PRIVATE = :cs_private
+  CS_PRIVATE_LINE = __LINE__ - 1
   private_constant :CS_PRIVATE
 end
 
+module ConstantSpecsThree
+  module ConstantSpecsTwo
+    Foo = :cs_three_foo
+  end
+end
+
+module ConstantSpecsTwo
+  Foo = :cs_two_foo
+end
+
 include ConstantSpecs::ModuleA
diff --git a/spec/ruby/fixtures/io.rb b/spec/ruby/fixtures/io.rb
new file mode 100644
index 0000000000..87ebbbb2bd
--- /dev/null
+++ b/spec/ruby/fixtures/io.rb
@@ -0,0 +1,12 @@
+module IOSpec
+  def self.exhaust_write_buffer(io)
+    written = 0
+    buf = " " * 4096
+
+    while true
+      written += io.write_nonblock(buf)
+    end
+  rescue Errno::EAGAIN, Errno::EWOULDBLOCK
+    written
+  end
+end
diff --git a/spec/ruby/language/BEGIN_spec.rb b/spec/ruby/language/BEGIN_spec.rb
index 58cc2bebfb..25db32b96a 100644
--- a/spec/ruby/language/BEGIN_spec.rb
+++ b/spec/ruby/language/BEGIN_spec.rb
@@ -15,7 +15,12 @@ describe "The BEGIN keyword" do
   end
 
   it "must appear in a top-level context" do
-    -> { eval "1.times { BEGIN { 1 } }" }.should raise_error(SyntaxError)
+    -> { eval "1.times { BEGIN { 1 } }" }.should.raise(SyntaxError)
+  end
+
+  it "uses top-level for self" do
+    eval("BEGIN { ScratchPad << self.to_s }", TOPLEVEL_BINDING)
+    ScratchPad.recorded.should == ['main']
   end
 
   it "runs first in a given code unit" do
diff --git a/spec/ruby/language/END_spec.rb b/spec/ruby/language/END_spec.rb
new file mode 100644
index 0000000000..c84f0cc9ac
--- /dev/null
+++ b/spec/ruby/language/END_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../spec_helper'
+require_relative '../shared/kernel/at_exit'
+
+describe "The END keyword" do
+  it_behaves_like :kernel_at_exit, :END
+
+  it "runs only once for multiple calls" do
+    ruby_exe("10.times { END { puts 'foo' }; } ").should == "foo\n"
+  end
+
+  it "is affected by the toplevel assignment" do
+    ruby_exe("foo = 'foo'; END { puts foo }").should == "foo\n"
+  end
+
+  it "warns when END is used in a method" do
+    ruby_exe(<<~ruby, args: "2>&1").should =~ /warning: END in method; use at_exit/
+      def foo
+        END { }
+      end
+    ruby
+  end
+
+  context "END blocks and at_exit callbacks are mixed" do
+    it "runs them all in reverse order of registration" do
+      ruby_exe(<<~ruby).should == "at_exit#2\nEND#2\nat_exit#1\nEND#1\n"
+        END { puts 'END#1' }
+        at_exit { puts 'at_exit#1' }
+        END { puts 'END#2' }
+        at_exit { puts 'at_exit#2' }
+      ruby
+    end
+  end
+end
diff --git a/spec/ruby/language/README b/spec/ruby/language/README
index 74eaf58709..ae08e17fb1 100644
--- a/spec/ruby/language/README
+++ b/spec/ruby/language/README
@@ -4,7 +4,7 @@ words. These words significantly describe major elements of the language,
 including flow control constructs like 'for' and 'while', conditional
 execution like 'if' and 'unless', exceptional execution control like 'rescue',
 etc. There are also literals for the basic "types" like String, Regexp, Array
-and Fixnum.
+and Integer.
 
 Behavioral specifications describe the behavior of concrete entities. Rather
 than using concepts of computation to organize these spec files, we use
diff --git a/spec/ruby/language/alias_spec.rb b/spec/ruby/language/alias_spec.rb
index 79348f70c3..4b3d36d308 100644
--- a/spec/ruby/language/alias_spec.rb
+++ b/spec/ruby/language/alias_spec.rb
@@ -52,6 +52,15 @@ describe "The alias keyword" do
     @obj.a.should == 5
   end
 
+  it "works with an interpolated symbol with non-literal embedded expression on the left-hand side" do
+    @meta.class_eval do
+      eval %Q{
+        alias :"#{'a' + ''.to_s}" value
+      }
+    end
+    @obj.a.should == 5
+  end
+
   it "works with a simple symbol on the right-hand side" do
     @meta.class_eval do
       alias a :value
@@ -80,6 +89,15 @@ describe "The alias keyword" do
     @obj.a.should == 5
   end
 
+  it "works with an interpolated symbol with non-literal embedded expression on the right-hand side" do
+    @meta.class_eval do
+      eval %Q{
+        alias a :"#{'value' + ''.to_s}"
+      }
+    end
+    @obj.a.should == 5
+  end
+
   it "adds the new method to the list of methods" do
     original_methods = @obj.methods
     @meta.class_eval do
@@ -122,7 +140,7 @@ describe "The alias keyword" do
     end
 
     @obj.__value.should == 5
-    -> { AliasObject.new.__value }.should raise_error(NoMethodError)
+    -> { AliasObject.new.__value }.should.raise(NoMethodError)
   end
 
   it "operates on the class/module metaclass when used in instance_eval" do
@@ -131,7 +149,7 @@ describe "The alias keyword" do
     end
 
     AliasObject.__klass_method.should == 7
-    -> { Object.__klass_method }.should raise_error(NoMethodError)
+    -> { Object.__klass_method }.should.raise(NoMethodError)
   end
 
   it "operates on the class/module metaclass when used in instance_exec" do
@@ -140,7 +158,7 @@ describe "The alias keyword" do
     end
 
     AliasObject.__klass_method2.should == 7
-    -> { Object.__klass_method2 }.should raise_error(NoMethodError)
+    -> { Object.__klass_method2 }.should.raise(NoMethodError)
   end
 
   it "operates on methods defined via attr, attr_reader, and attr_accessor" do
@@ -218,31 +236,44 @@ describe "The alias keyword" do
     subclass.new.test("testing").should == 4
   end
 
-  it "is not allowed against Fixnum or String instances" do
+  it "is not allowed against Integer or String instances" do
     -> do
       1.instance_eval do
         alias :foo :to_s
       end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
 
     -> do
       :blah.instance_eval do
         alias :foo :to_s
       end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "on top level defines the alias on Object" do
     # because it defines on the default definee / current module
-    ruby_exe("def foo; end; alias bla foo; print method(:bla).owner", escape: true).should == "Object"
+    ruby_exe("def foo; end; alias bla foo; print method(:bla).owner").should == "Object"
   end
 
   it "raises a NameError when passed a missing name" do
-    -> { @meta.class_eval { alias undef_method not_exist } }.should raise_error(NameError) { |e|
+    -> { @meta.class_eval { alias undef_method not_exist } }.should.raise(NameError) { |e|
       # a NameError and not a NoMethodError
       e.class.should == NameError
     }
   end
+
+  it "defines the method on the aliased class when the original method is from a parent class" do
+    parent = Class.new do
+      def parent_method
+      end
+    end
+    child = Class.new(parent) do
+      alias parent_method_alias parent_method
+    end
+
+    child.instance_method(:parent_method_alias).owner.should == child
+    child.instance_methods(false).should.include?(:parent_method_alias)
+  end
 end
 
 describe "The alias keyword" do
@@ -255,4 +286,9 @@ describe "The alias keyword" do
     code = '$a = 1; $b = 2; alias $b $a; p [$a, $b]; $b = 3; p [$a, $b]'
     ruby_exe(code).should == "[1, 1]\n[3, 3]\n"
   end
+
+  it "supports aliasing twice the same global variables" do
+    code = '$a = 1; alias $b $a; alias $b $a; p [$a, $b]'
+    ruby_exe(code).should == "[1, 1]\n"
+  end
 end
diff --git a/spec/ruby/language/and_spec.rb b/spec/ruby/language/and_spec.rb
index 55a2a3103a..c5c255989b 100644
--- a/spec/ruby/language/and_spec.rb
+++ b/spec/ruby/language/and_spec.rb
@@ -5,7 +5,7 @@ describe "The '&&' statement" do
   it "short-circuits evaluation at the first condition to be false" do
     x = nil
     true && false && x = 1
-    x.should be_nil
+    x.should == nil
   end
 
   it "evaluates to the first condition not to be true" do
@@ -33,9 +33,9 @@ describe "The '&&' statement" do
   end
 
   it "treats empty expressions as nil" do
-    (() && true).should be_nil
-    (true && ()).should be_nil
-    (() && ()).should be_nil
+    (() && true).should == nil
+    (true && ()).should == nil
+    (() && ()).should == nil
   end
 
 end
@@ -44,7 +44,7 @@ describe "The 'and' statement" do
   it "short-circuits evaluation at the first condition to be false" do
     x = nil
     true and false and x = 1
-    x.should be_nil
+    x.should == nil
   end
 
   it "evaluates to the first condition not to be true" do
@@ -72,9 +72,9 @@ describe "The 'and' statement" do
   end
 
   it "treats empty expressions as nil" do
-    (() and true).should be_nil
-    (true and ()).should be_nil
-    (() and ()).should be_nil
+    (() and true).should == nil
+    (true and ()).should == nil
+    (() and ()).should == nil
   end
 
 end
diff --git a/spec/ruby/language/array_spec.rb b/spec/ruby/language/array_spec.rb
index 2583cffbf7..78cf36c201 100644
--- a/spec/ruby/language/array_spec.rb
+++ b/spec/ruby/language/array_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/array'
 describe "Array literals" do
   it "[] should return a new array populated with the given elements" do
     array = [1, 'a', nil]
-    array.should be_kind_of(Array)
+    array.should.is_a?(Array)
     array[0].should == 1
     array[1].should == 'a'
     array[2].should == nil
@@ -12,7 +12,7 @@ describe "Array literals" do
 
   it "[] treats empty expressions as nil elements" do
     array = [0, (), 2, (), 4]
-    array.should be_kind_of(Array)
+    array.should.is_a?(Array)
     array[0].should == 0
     array[1].should == nil
     array[2].should == 2
@@ -89,7 +89,7 @@ describe "The unpacking splat operator (*)" do
   it "returns a new array containing the same values when applied to an array inside an empty array" do
     splatted_array = [3, 4, 5]
     [*splatted_array].should == splatted_array
-    [*splatted_array].should_not equal(splatted_array)
+    [*splatted_array].should_not.equal?(splatted_array)
   end
 
   it "unpacks the start and count arguments in an array slice assignment" do
@@ -135,7 +135,7 @@ describe "The unpacking splat operator (*)" do
 
   it "when applied to a non-Array value uses it unchanged if it does not respond_to?(:to_a)" do
     obj = Object.new
-    obj.should_not respond_to(:to_a)
+    obj.should_not.respond_to?(:to_a)
     [1, *obj].should == [1, obj]
   end
 
@@ -155,8 +155,12 @@ describe "The unpacking splat operator (*)" do
     b = [1, 0]
     [*a, 3, *a, *b].should == [1, 2, 3, 1, 2, 1, 0]
   end
-end
-
-describe "The packing splat operator (*)" do
 
+  ruby_version_is "4.0" do
+    it "does not call #to_a on nil" do
+      e = nil
+      e.should_not_receive(:to_a)
+      [*e].should == []
+    end
+  end
 end
diff --git a/spec/ruby/language/assignments_spec.rb b/spec/ruby/language/assignments_spec.rb
new file mode 100644
index 0000000000..d621c9f0c6
--- /dev/null
+++ b/spec/ruby/language/assignments_spec.rb
@@ -0,0 +1,582 @@
+require_relative '../spec_helper'
+
+# Should be synchronized with spec/ruby/language/optional_assignments_spec.rb
+# Some specs for assignments are located in language/variables_spec.rb
+describe 'Assignments' do
+  describe 'using =' do
+    describe 'evaluation order' do
+      it 'evaluates expressions left to right when assignment with an accessor' do
+        object = Object.new
+        def object.a=(value) end
+        ScratchPad.record []
+
+        (ScratchPad << :receiver; object).a = (ScratchPad << :rhs; :value)
+        ScratchPad.recorded.should == [:receiver, :rhs]
+      end
+
+      it 'evaluates expressions left to right when assignment with a #[]=' do
+        object = Object.new
+        def object.[]=(_, _) end
+        ScratchPad.record []
+
+        (ScratchPad << :receiver; object)[(ScratchPad << :argument; :a)] = (ScratchPad << :rhs; :value)
+        ScratchPad.recorded.should == [:receiver, :argument, :rhs]
+      end
+
+      it 'evaluates expressions left to right when assignment with compounded constant' do
+        m = Module.new
+        ScratchPad.record []
+
+        (ScratchPad << :module; m)::A = (ScratchPad << :rhs; :value)
+        ScratchPad.recorded.should == [:module, :rhs]
+      end
+
+      it 'raises TypeError after evaluation of right-hand-side when compounded constant module is not a module' do
+        ScratchPad.record []
+
+        -> {
+          (:not_a_module)::A = (ScratchPad << :rhs; :value)
+        }.should.raise(TypeError)
+
+        ScratchPad.recorded.should == [:rhs]
+      end
+    end
+
+    context "given block argument" do
+      before do
+        @klass = Class.new do
+          def initialize(h) @h = h end
+          def [](k, &block) @h[k]; end
+          def []=(k, v, &block) @h[k] = v; end
+        end
+      end
+
+      ruby_version_is ""..."3.4" do
+        it "accepts block argument" do
+          obj = @klass.new(a: 1)
+          block = proc {}
+
+          eval "obj[:a, &block] = 2"
+          eval("obj[:a, &block]").should == 2
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "raises SyntaxError" do
+          obj = @klass.new(a: 1)
+          block = proc {}
+
+          -> {
+            eval "obj[:a, &block] = 2"
+          }.should.raise(SyntaxError, /unexpected block arg given in index assignment|block arg given in index assignment/)
+        end
+      end
+    end
+
+    context "given keyword arguments" do
+      before do
+        @klass = Class.new do
+          attr_reader :x
+
+          def []=(*args, **kw)
+            @x = [args, kw]
+          end
+        end
+      end
+
+      ruby_version_is ""..."3.4" do
+        it "supports keyword arguments in index assignments" do
+          a = @klass.new
+          eval "a[1, 2, 3, b: 4] = 5"
+          a.x.should == [[1, 2, 3, {b: 4}, 5], {}]
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "raises SyntaxError when given keyword arguments in index assignments" do
+          a = @klass.new
+          -> { eval "a[1, 2, 3, b: 4] = 5" }.should.raise(SyntaxError,
+            /keywords are not allowed in index assignment expressions|keyword arg given in index assignment/) # prism|parse.y
+        end
+      end
+    end
+  end
+
+  describe 'using +=' do
+    describe 'using an accessor' do
+      before do
+        klass = Class.new { attr_accessor :b }
+        @a    = klass.new
+      end
+
+      it 'does evaluate receiver only once when assigns' do
+        ScratchPad.record []
+        @a.b = 1
+
+        (ScratchPad << :evaluated; @a).b += 2
+
+        ScratchPad.recorded.should == [:evaluated]
+        @a.b.should == 3
+      end
+
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(n) @a = n end
+          def public_method(n); self.a += n end
+          private
+          def a; @a end
+          def a=(n) @a = n; 42 end
+        end
+
+        a = klass_with_private_methods.new(0)
+        a.public_method(2).should == 2
+      end
+    end
+
+    describe 'using a #[]' do
+      before do
+        klass = Class.new do
+          def [](k)
+            @hash ||= {}
+            @hash[k]
+          end
+
+          def []=(k, v)
+            @hash ||= {}
+            @hash[k] = v
+            7
+          end
+        end
+        @b = klass.new
+      end
+
+      it 'evaluates receiver only once when assigns' do
+        ScratchPad.record []
+        a = {k: 1}
+
+        (ScratchPad << :evaluated; a)[:k] += 2
+
+        ScratchPad.recorded.should == [:evaluated]
+        a[:k].should == 3
+      end
+
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(h) @a = h end
+          def public_method(k, n); self[k] += n end
+          private
+          def [](k) @a[k] end
+          def []=(k, v) @a[k] = v; 42 end
+        end
+
+        a = klass_with_private_methods.new(k: 0)
+        a.public_method(:k, 2).should == 2
+      end
+
+      context "given block argument" do
+        before do
+          @klass = Class.new do
+            def initialize(h) @h = h end
+            def [](k, &block) @h[k]; end
+            def []=(k, v, &block) @h[k] = v; end
+          end
+        end
+
+        ruby_version_is ""..."3.4" do
+          it "accepts block argument" do
+            obj = @klass.new(a: 1)
+            block = proc {}
+
+            eval "obj[:a, &block] += 2"
+            eval("obj[:a, &block]").should == 3
+          end
+        end
+
+        ruby_version_is "3.4" do
+          it "raises SyntaxError" do
+            obj = @klass.new(a: 1)
+            block = proc {}
+
+            -> {
+              eval "obj[:a, &block] += 2"
+            }.should.raise(SyntaxError, /unexpected block arg given in index assignment|block arg given in index assignment/)
+          end
+        end
+      end
+
+      context "given keyword arguments" do
+        before do
+          @klass = Class.new do
+            attr_reader :x
+
+            def [](*args)
+              100
+            end
+
+            def []=(*args, **kw)
+              @x = [args, kw]
+            end
+          end
+        end
+
+        ruby_version_is ""..."3.4" do
+          it "supports keyword arguments in index assignments" do
+            a = @klass.new
+            eval "a[1, 2, 3, b: 4] += 5"
+            a.x.should == [[1, 2, 3, 105], {b: 4}]
+          end
+        end
+
+        ruby_version_is "3.4" do
+          it "raises SyntaxError when given keyword arguments in index assignments" do
+            a = @klass.new
+            -> { eval "a[1, 2, 3, b: 4] += 5" }.should.raise(SyntaxError,
+              /keywords are not allowed in index assignment expressions|keyword arg given in index assignment/) # prism|parse.y
+          end
+        end
+      end
+
+      context 'splatted argument' do
+        it 'correctly handles it' do
+          @b[:m] = 10
+          (@b[*[:m]] += 10).should == 20
+          @b[:m].should == 20
+
+          @b[:n] = 10
+          (@b[*(1; [:n])] += 10).should == 20
+          @b[:n].should == 20
+
+          @b[:k] = 10
+          (@b[*begin 1; [:k] end] += 10).should == 20
+          @b[:k].should == 20
+        end
+
+        it 'calls #to_a only once' do
+          k = Object.new
+          def k.to_a
+            ScratchPad << :to_a
+            [:k]
+          end
+
+          ScratchPad.record []
+          @b[:k] = 10
+          (@b[*k] += 10).should == 20
+          @b[:k].should == 20
+          ScratchPad.recorded.should == [:to_a]
+        end
+
+        it 'correctly handles a nested splatted argument' do
+          @b[:k] = 10
+          (@b[*[*[:k]]] += 10).should == 20
+          @b[:k].should == 20
+        end
+
+        it 'correctly handles multiple nested splatted arguments' do
+          klass_with_multiple_parameters = Class.new do
+            def [](k1, k2, k3)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"]
+            end
+
+            def []=(k1, k2, k3, v)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"] = v
+              7
+            end
+          end
+          a = klass_with_multiple_parameters.new
+
+          a[:a, :b, :c] = 10
+          (a[*[:a], *[:b], *[:c]] += 10).should == 20
+          a[:a, :b, :c].should == 20
+        end
+      end
+    end
+
+    describe 'using compounded constants' do
+      it 'causes side-effects of the module part to be applied only once (when assigns)' do
+        module ConstantSpecs
+          OpAssignTrue = 1
+        end
+
+        suppress_warning do # already initialized constant
+          x = 0
+          (x += 1; ConstantSpecs)::OpAssignTrue += 2
+          x.should == 1
+          ConstantSpecs::OpAssignTrue.should == 3
+        end
+
+        ConstantSpecs.send :remove_const, :OpAssignTrue
+      end
+    end
+  end
+end
+
+# generic cases
+describe 'Multiple assignments' do
+  it 'assigns multiple targets when assignment with an accessor' do
+    object = Object.new
+    class << object
+      attr_accessor :a, :b
+    end
+
+    object.a, object.b = :a, :b
+
+    object.a.should == :a
+    object.b.should == :b
+  end
+
+  it 'assigns multiple targets when assignment with a nested accessor' do
+    object = Object.new
+    class << object
+      attr_accessor :a, :b
+    end
+
+    (object.a, object.b), c = [:a, :b], nil
+
+    object.a.should == :a
+    object.b.should == :b
+  end
+
+  it 'assigns multiple targets when assignment with a #[]=' do
+    object = Object.new
+    class << object
+      def []=(k, v) (@h ||= {})[k] = v; end
+      def [](k) (@h ||= {})[k]; end
+    end
+
+    object[:a], object[:b] = :a, :b
+
+    object[:a].should == :a
+    object[:b].should == :b
+  end
+
+  it 'assigns multiple targets when assignment with a nested #[]=' do
+    object = Object.new
+    class << object
+      def []=(k, v) (@h ||= {})[k] = v; end
+      def [](k) (@h ||= {})[k]; end
+    end
+
+    (object[:a], object[:b]), c = [:v1, :v2], nil
+
+    object[:a].should == :v1
+    object[:b].should == :v2
+  end
+
+  it 'assigns multiple targets when assignment with compounded constant' do
+    m = Module.new
+
+    m::A, m::B = :a, :b
+
+    m::A.should == :a
+    m::B.should == :b
+  end
+
+  it 'assigns multiple targets when assignment with a nested compounded constant' do
+    m = Module.new
+
+    (m::A, m::B), c = [:a, :b], nil
+
+    m::A.should == :a
+    m::B.should == :b
+  end
+end
+
+describe 'Multiple assignments' do
+  describe 'evaluation order' do
+    it 'evaluates expressions left to right when assignment with an accessor' do
+      object = Object.new
+      def object.a=(value) end
+      ScratchPad.record []
+
+      (ScratchPad << :a; object).a, (ScratchPad << :b; object).a = (ScratchPad << :c; :c), (ScratchPad << :d; :d)
+      ScratchPad.recorded.should == [:a, :b, :c, :d]
+    end
+
+    it 'evaluates expressions left to right when assignment with a nested accessor' do
+      object = Object.new
+      def object.a=(value) end
+      ScratchPad.record []
+
+      ((ScratchPad << :a; object).a, foo), bar = [(ScratchPad << :b; :b)]
+      ScratchPad.recorded.should == [:a, :b]
+    end
+
+    it 'evaluates expressions left to right when assignment with a deeply nested accessor' do
+      o = Object.new
+      def o.a=(value) end
+      def o.b=(value) end
+      def o.c=(value) end
+      def o.d=(value) end
+      def o.e=(value) end
+      def o.f=(value) end
+      ScratchPad.record []
+
+      (ScratchPad << :a; o).a,
+        ((ScratchPad << :b; o).b,
+        ((ScratchPad << :c; o).c, (ScratchPad << :d; o).d),
+        (ScratchPad << :e; o).e),
+      (ScratchPad << :f; o).f = (ScratchPad << :value; :value)
+
+      ScratchPad.recorded.should == [:a, :b, :c, :d, :e, :f, :value]
+    end
+
+    it 'evaluates expressions left to right when assignment with a #[]=' do
+      object = Object.new
+      def object.[]=(_, _) end
+      ScratchPad.record []
+
+      (ScratchPad << :a; object)[(ScratchPad << :b; :b)], (ScratchPad << :c; object)[(ScratchPad << :d; :d)] = (ScratchPad << :e; :e), (ScratchPad << :f; :f)
+      ScratchPad.recorded.should == [:a, :b, :c, :d, :e, :f]
+    end
+
+    it 'evaluates expressions left to right when assignment with a nested #[]=' do
+      object = Object.new
+      def object.[]=(_, _) end
+      ScratchPad.record []
+
+      ((ScratchPad << :a; object)[(ScratchPad << :b; :b)], foo), bar = [(ScratchPad << :c; :c)]
+      ScratchPad.recorded.should == [:a, :b, :c]
+    end
+
+    it 'evaluates expressions left to right when assignment with a deeply nested #[]=' do
+      o = Object.new
+      def o.[]=(_, _) end
+      ScratchPad.record []
+
+      (ScratchPad << :ra; o)[(ScratchPad << :aa; :aa)],
+        ((ScratchPad << :rb; o)[(ScratchPad << :ab; :ab)],
+        ((ScratchPad << :rc; o)[(ScratchPad << :ac; :ac)], (ScratchPad << :rd; o)[(ScratchPad << :ad; :ad)]),
+        (ScratchPad << :re; o)[(ScratchPad << :ae; :ae)]),
+      (ScratchPad << :rf; o)[(ScratchPad << :af; :af)] = (ScratchPad << :value; :value)
+
+      ScratchPad.recorded.should == [:ra, :aa, :rb, :ab, :rc, :ac, :rd, :ad, :re, :ae, :rf, :af, :value]
+    end
+
+    it 'evaluates expressions left to right when assignment with compounded constant' do
+      m = Module.new
+      ScratchPad.record []
+
+      (ScratchPad << :a; m)::A, (ScratchPad << :b; m)::B = (ScratchPad << :c; :c), (ScratchPad << :d; :d)
+      ScratchPad.recorded.should == [:a, :b, :c, :d]
+    end
+
+    it 'evaluates expressions left to right when assignment with a nested compounded constant' do
+      m = Module.new
+      ScratchPad.record []
+
+      ((ScratchPad << :a; m)::A, foo), bar = [(ScratchPad << :b; :b)]
+      ScratchPad.recorded.should == [:a, :b]
+    end
+
+    it 'evaluates expressions left to right when assignment with deeply nested compounded constants' do
+      m = Module.new
+      ScratchPad.record []
+
+      (ScratchPad << :a; m)::A,
+        ((ScratchPad << :b; m)::B,
+        ((ScratchPad << :c; m)::C, (ScratchPad << :d; m)::D),
+        (ScratchPad << :e; m)::E),
+      (ScratchPad << :f; m)::F = (ScratchPad << :value; :value)
+
+      ScratchPad.recorded.should == [:a, :b, :c, :d, :e, :f, :value]
+    end
+  end
+
+  context 'when assignment with method call and receiver is self' do
+    it 'assigns values correctly when assignment with accessor' do
+      object = Object.new
+      class << object
+        attr_accessor :a, :b
+
+        def assign(v1, v2)
+          self.a, self.b = v1, v2
+        end
+      end
+
+      object.assign :v1, :v2
+      object.a.should == :v1
+      object.b.should == :v2
+    end
+
+    it 'evaluates expressions right to left when assignment with a nested accessor' do
+      object = Object.new
+      class << object
+        attr_accessor :a, :b
+
+        def assign(v1, v2)
+          (self.a, self.b), c = [v1, v2], nil
+        end
+      end
+
+      object.assign :v1, :v2
+      object.a.should == :v1
+      object.b.should == :v2
+    end
+
+    it 'assigns values correctly when assignment with a #[]=' do
+      object = Object.new
+      class << object
+        def []=(key, v)
+          @h ||= {}
+          @h[key] = v
+        end
+
+        def [](key)
+          (@h || {})[key]
+        end
+
+        def assign(k1, v1, k2, v2)
+          self[k1], self[k2] = v1, v2
+        end
+      end
+
+      object.assign :k1, :v1, :k2, :v2
+      object[:k1].should == :v1
+      object[:k2].should == :v2
+    end
+
+    it 'assigns values correctly when assignment with a nested #[]=' do
+      object = Object.new
+      class << object
+        def []=(key, v)
+          @h ||= {}
+          @h[key] = v
+        end
+
+        def [](key)
+          (@h || {})[key]
+        end
+
+        def assign(k1, v1, k2, v2)
+          (self[k1], self[k2]), c = [v1, v2], nil
+        end
+      end
+
+      object.assign :k1, :v1, :k2, :v2
+      object[:k1].should == :v1
+      object[:k2].should == :v2
+    end
+
+    it 'assigns values correctly when assignment with compounded constant' do
+      m = Module.new
+      m.module_exec do
+        self::A, self::B = :v1, :v2
+      end
+
+      m::A.should == :v1
+      m::B.should == :v2
+    end
+
+    it 'assigns values correctly when assignment with a nested compounded constant' do
+      m = Module.new
+      m.module_exec do
+        (self::A, self::B), c = [:v1, :v2], nil
+      end
+
+      m::A.should == :v1
+      m::B.should == :v2
+    end
+  end
+end
diff --git a/spec/ruby/language/block_spec.rb b/spec/ruby/language/block_spec.rb
index e5c9fcb762..5bdb993aea 100644
--- a/spec/ruby/language/block_spec.rb
+++ b/spec/ruby/language/block_spec.rb
@@ -13,7 +13,7 @@ describe "A block yielded a single" do
 
     it "receives the identical Array object" do
       ary = [1, 2]
-      m(ary) { |a| a }.should equal(ary)
+      m(ary) { |a| a }.should.equal?(ary)
     end
 
     it "assigns the Array to a single rest argument" do
@@ -40,111 +40,98 @@ describe "A block yielded a single" do
       m([1, 2]) { |a=5, b, c, d| [a, b, c, d] }.should == [5, 1, 2, nil]
     end
 
-    it "assigns elements to required arguments when a keyword rest argument is present" do
-      m([1, 2]) { |a, **k| [a, k] }.should == [1, {}]
+    it "assigns elements to pre arguments" do
+      m([1, 2]) { |a, b, c, d=5| [a, b, c, d] }.should == [1, 2, nil, 5]
     end
 
-    it "assigns elements to mixed argument types" do
-      suppress_keyword_warning do
-        result = m([1, 2, 3, {x: 9}]) { |a, b=5, *c, d, e: 2, **k| [a, b, c, d, e, k] }
-        result.should == [1, 2, [], 3, 2, {x: 9}]
-      end
+    it "assigns elements to pre and post arguments" do
+      m([1               ]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 5, 6, nil, nil]
+      m([1, 2            ]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 5, 6, 2, nil]
+      m([1, 2, 3         ]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 5, 6, 2, 3]
+      m([1, 2, 3, 4      ]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 2, 6, 3, 4]
+      m([1, 2, 3, 4, 5   ]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 2, 3, 4, 5]
+      m([1, 2, 3, 4, 5, 6]) { |a, b=5, c=6, d, e| [a, b, c, d, e] }.should == [1, 2, 3, 4, 5]
     end
 
-    it "assigns symbol keys from a Hash to keyword arguments" do
-      suppress_keyword_warning do
-        result = m(["a" => 1, a: 10]) { |a=nil, **b| [a, b] }
-        result.should == [{"a" => 1}, a: 10]
-      end
+    it "assigns elements to pre and post arguments when *rest is present" do
+      m([1               ]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 5, 6, [], nil, nil]
+      m([1, 2            ]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 5, 6, [], 2, nil]
+      m([1, 2, 3         ]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 5, 6, [], 2, 3]
+      m([1, 2, 3, 4      ]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 2, 6, [], 3, 4]
+      m([1, 2, 3, 4, 5   ]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 2, 3, [], 4, 5]
+      m([1, 2, 3, 4, 5, 6]) { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.should == [1, 2, 3, [4], 5, 6]
     end
 
-    it "assigns symbol keys from a Hash returned by #to_hash to keyword arguments" do
-      suppress_keyword_warning do
-        obj = mock("coerce block keyword arguments")
-        obj.should_receive(:to_hash).and_return({"a" => 1, b: 2})
+    it "does not autosplat single argument to required arguments when a keyword rest argument is present" do
+      m([1, 2]) { |a, **k| [a, k] }.should == [[1, 2], {}]
+    end
 
-        result = m([obj]) { |a=nil, **b| [a, b] }
-        result.should == [{"a" => 1}, b: 2]
-      end
+    it "does not autosplat single argument to required arguments when keyword arguments are present" do
+      m([1, 2]) { |a, b: :b, c: :c| [a, b, c] }.should == [[1, 2], :b, :c]
     end
 
-    ruby_version_is ""..."2.7" do
-      it "calls #to_hash on the argument and uses resulting hash as first argument when optional argument and keyword argument accepted" do
-        obj = mock("coerce block keyword arguments")
-        obj.should_receive(:to_hash).and_return({"a" => 1, "b" => 2})
+    it "raises error when required keyword arguments are present" do
+      -> {
+        m([1, 2]) { |a, b:, c:| [a, b, c] }
+      }.should.raise(ArgumentError, "missing keywords: :b, :c")
+    end
 
-        result = m([obj]) { |a=nil, **b| [a, b] }
-        result.should == [{"a" => 1, "b" => 2}, {}]
-      end
+    it "assigns elements to mixed argument types" do
+      result = m([1, 2, 3, {x: 9}]) { |a, b=5, *c, d, e: 2, **k| [a, b, c, d, e, k] }
+      result.should == [1, 2, [3], {x: 9}, 2, {}]
     end
 
-    ruby_version_is "2.7" do
-      it "calls #to_hash on the argument but ignores result when optional argument and keyword argument accepted" do
+    it "does not treat final Hash as keyword arguments and does not autosplat" do
+      result = m(["a" => 1, a: 10]) { |a=nil, **b| [a, b] }
+      result.should == [[{"a" => 1, a: 10}], {}]
+    end
+
+    it "does not call #to_hash on final argument to get keyword arguments and does not autosplat" do
+      suppress_keyword_warning do
         obj = mock("coerce block keyword arguments")
-        obj.should_receive(:to_hash).and_return({"a" => 1, "b" => 2})
+        obj.should_not_receive(:to_hash)
 
         result = m([obj]) { |a=nil, **b| [a, b] }
-        result.should == [obj, {}]
+        result.should == [[obj], {}]
       end
     end
 
+    it "does not call #to_hash on the argument when optional argument and keyword argument accepted and does not autosplat" do
+      obj = mock("coerce block keyword arguments")
+      obj.should_not_receive(:to_hash)
+
+      result = m([obj]) { |a=nil, **b| [a, b] }
+      result.should == [[obj], {}]
+    end
+
     describe "when non-symbol keys are in a keyword arguments Hash" do
-      it "separates non-symbol keys and symbol keys" do
+      it "does not separate non-symbol keys and symbol keys and does not autosplat" do
         suppress_keyword_warning do
           result = m(["a" => 10, b: 2]) { |a=nil, **b| [a, b] }
-          result.should == [{"a" => 10}, {b: 2}]
+          result.should == [[{"a" => 10, b: 2}], {}]
         end
       end
     end
 
-    it "does not treat hashes with string keys as keyword arguments" do
+    it "does not treat hashes with string keys as keyword arguments and does not autosplat" do
       result = m(["a" => 10]) { |a = nil, **b| [a, b] }
-      result.should == [{"a" => 10}, {}]
-    end
-
-    it "calls #to_hash on the last element if keyword arguments are present" do
-      suppress_keyword_warning do
-        obj = mock("destructure block keyword arguments")
-        obj.should_receive(:to_hash).and_return({x: 9})
-
-        result = m([1, 2, 3, obj]) { |a, *b, c, **k| [a, b, c, k] }
-        result.should == [1, [2], 3, {x: 9}]
-      end
-    end
-
-    it "assigns the last element to a non-keyword argument if #to_hash returns nil" do
-      suppress_keyword_warning do
-        obj = mock("destructure block keyword arguments")
-        obj.should_receive(:to_hash).and_return(nil)
-
-        result = m([1, 2, 3, obj]) { |a, *b, c, **k| [a, b, c, k] }
-        result.should == [1, [2, 3], obj, {}]
-      end
+      result.should == [[{"a" => 10}], {}]
     end
 
-    it "calls #to_hash on the last element when there are more arguments than parameters" do
-      suppress_keyword_warning do
-        x = mock("destructure matching block keyword argument")
-        x.should_receive(:to_hash).and_return({x: 9})
-
-        result = m([1, 2, 3, {y: 9}, 4, 5, x]) { |a, b=5, c, **k| [a, b, c, k] }
-        result.should == [1, 2, 3, {x: 9}]
-      end
-    end
-
-    it "raises a TypeError if #to_hash does not return a Hash" do
+    it "does not call #to_hash on the last element if keyword arguments are present" do
       obj = mock("destructure block keyword arguments")
-      obj.should_receive(:to_hash).and_return(1)
+      obj.should_not_receive(:to_hash)
 
-      -> { m([1, 2, 3, obj]) { |a, *b, c, **k| } }.should raise_error(TypeError)
+      result = m([1, 2, 3, obj]) { |a, *b, c, **k| [a, b, c, k] }
+      result.should == [1, [2, 3], obj, {}]
     end
 
-    it "raises the error raised inside #to_hash" do
-      obj = mock("destructure block keyword arguments")
-      error = RuntimeError.new("error while converting to a hash")
-      obj.should_receive(:to_hash).and_raise(error)
+    it "does not call #to_hash on the last element when there are more arguments than parameters" do
+      x = mock("destructure matching block keyword argument")
+      x.should_not_receive(:to_hash)
 
-      -> { m([1, 2, 3, obj]) { |a, *b, c, **k| } }.should raise_error(error)
+      result = m([1, 2, 3, {y: 9}, 4, 5, x]) { |a, b=5, c, **k| [a, b, c, k] }
+      result.should == [1, 2, 3, {}]
     end
 
     it "does not call #to_ary on the Array" do
@@ -191,11 +178,70 @@ describe "A block yielded a single" do
       m(obj) { |a, b, c| [a, b, c] }.should == [obj, nil, nil]
     end
 
+    it "receives the object if it does not respond to #to_ary" do
+      obj = Object.new
+
+      m(obj) { |a, b, c| [a, b, c] }.should == [obj, nil, nil]
+    end
+
+    it "calls #respond_to? to check if object has method #to_ary" do
+      obj = mock("destructure block arguments")
+      obj.should_receive(:respond_to?).with(:to_ary, true).and_return(true)
+      obj.should_receive(:to_ary).and_return([1, 2])
+
+      m(obj) { |a, b, c| [a, b, c] }.should == [1, 2, nil]
+    end
+
+    it "calls #respond_to? on a BasicObject to check if object has method #to_ary" do
+      ScratchPad.record []
+      obj = BasicObject.new
+      def obj.respond_to?(name, *)
+        ScratchPad << [:respond_to?, name]
+        name == :to_ary ? true : super
+      end
+      def obj.to_ary
+        ScratchPad << :to_ary
+        [1, 2]
+      end
+
+      m(obj) { |a, b, c| [a, b, c] }.should == [1, 2, nil]
+      ScratchPad.recorded.should == [[:respond_to?, :to_ary], :to_ary]
+    end
+
+    it "receives the object if it does not respond to #respond_to?" do
+      obj = BasicObject.new
+
+      m(obj) { |a, b, c| [a, b, c] }.should == [obj, nil, nil]
+    end
+
+    it "calls #to_ary on the object when it is defined dynamically" do
+      obj = Object.new
+      def obj.method_missing(name, *args, &block)
+        if name == :to_ary
+          [1, 2]
+        else
+          super
+        end
+      end
+      def obj.respond_to_missing?(name, include_private)
+        name == :to_ary
+      end
+
+      m(obj) { |a, b, c| [a, b, c] }.should == [1, 2, nil]
+    end
+
     it "raises a TypeError if #to_ary does not return an Array" do
       obj = mock("destructure block arguments")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { m(obj) { |a, b| } }.should raise_error(TypeError)
+      -> { m(obj) { |a, b| } }.should.raise(TypeError)
+    end
+
+    it "raises error transparently if #to_ary raises error on its own" do
+      obj = Object.new
+      def obj.to_ary; raise "Exception raised in #to_ary" end
+
+      -> { m(obj) { |a, b| } }.should.raise(RuntimeError, "Exception raised in #to_ary")
     end
   end
 end
@@ -244,10 +290,8 @@ describe "A block" do
       @y.s(0) { 1 }.should == 1
     end
 
-    ruby_version_is "2.5" do
-      it "may include a rescue clause" do
-        eval("@y.z do raise ArgumentError; rescue ArgumentError; 7; end").should == 7
-      end
+    it "may include a rescue clause" do
+      @y.z do raise ArgumentError; rescue ArgumentError; 7; end.should == 7
     end
   end
 
@@ -260,16 +304,14 @@ describe "A block" do
       @y.s(0) { || 1 }.should == 1
     end
 
-    ruby_version_is "2.5" do
-      it "may include a rescue clause" do
-        eval('@y.z do || raise ArgumentError; rescue ArgumentError; 7; end').should == 7
-      end
+    it "may include a rescue clause" do
+      @y.z do || raise ArgumentError; rescue ArgumentError; 7; end.should == 7
     end
   end
 
   describe "taking |a| arguments" do
     it "assigns nil to the argument when no values are yielded" do
-      @y.z { |a| a }.should be_nil
+      @y.z { |a| a }.should == nil
     end
 
     it "assigns the value yielded to the argument" do
@@ -280,7 +322,7 @@ describe "A block" do
       obj = mock("block yield to_ary")
       obj.should_not_receive(:to_ary)
 
-      @y.s(obj) { |a| a }.should equal(obj)
+      @y.s(obj) { |a| a }.should.equal?(obj)
     end
 
     it "assigns the first value yielded to the argument" do
@@ -291,10 +333,8 @@ describe "A block" do
       @y.s([1, 2]) { |a| a }.should == [1, 2]
     end
 
-    ruby_version_is "2.5" do
-      it "may include a rescue clause" do
-        eval('@y.s(1) do |x| raise ArgumentError; rescue ArgumentError; 7; end').should == 7
-      end
+    it "may include a rescue clause" do
+      @y.s(1) do |x| raise ArgumentError; rescue ArgumentError; 7; end.should == 7
     end
   end
 
@@ -358,16 +398,15 @@ describe "A block" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { @y.s(obj) { |a, b| } }.should raise_error(TypeError)
+      -> { @y.s(obj) { |a, b| } }.should.raise(TypeError)
     end
 
     it "raises the original exception if #to_ary raises an exception" do
       obj = mock("block yield to_ary raising an exception")
       obj.should_receive(:to_ary).and_raise(ZeroDivisionError)
 
-      -> { @y.s(obj) { |a, b| } }.should raise_error(ZeroDivisionError)
+      -> { @y.s(obj) { |a, b| } }.should.raise(ZeroDivisionError)
     end
-
   end
 
   describe "taking |a, *b| arguments" do
@@ -422,7 +461,7 @@ describe "A block" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { @y.s(obj) { |a, *b| } }.should raise_error(TypeError)
+      -> { @y.s(obj) { |a, *b| } }.should.raise(TypeError)
     end
   end
 
@@ -500,7 +539,7 @@ describe "A block" do
 
   describe "taking |a, | arguments" do
     it "assigns nil to the argument when no values are yielded" do
-      @y.z { |a, | a }.should be_nil
+      @y.z { |a, | a }.should == nil
     end
 
     it "assigns the argument a single value yielded" do
@@ -516,7 +555,7 @@ describe "A block" do
     end
 
     it "assigns nil to the argument when passed an empty Array" do
-      @y.s([]) { |a, | a }.should be_nil
+      @y.s([]) { |a, | a }.should == nil
     end
 
     it "assigns the argument the first element of the Array when passed a single Array" do
@@ -547,7 +586,7 @@ describe "A block" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { @y.s(obj) { |a, | } }.should raise_error(TypeError)
+      -> { @y.s(obj) { |a, | } }.should.raise(TypeError)
     end
   end
 
@@ -589,7 +628,7 @@ describe "A block" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { @y.s(obj) { |(a, b)| } }.should raise_error(TypeError)
+      -> { @y.s(obj) { |(a, b)| } }.should.raise(TypeError)
     end
   end
 
@@ -630,7 +669,7 @@ describe "A block" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      -> { @y.s(obj) { |(a, b), c| } }.should raise_error(TypeError)
+      -> { @y.s(obj) { |(a, b), c| } }.should.raise(TypeError)
     end
   end
 
@@ -689,15 +728,51 @@ describe "A block" do
 
   describe "taking identically-named arguments" do
     it "raises a SyntaxError for standard arguments" do
-      -> { eval "lambda { |x,x| }" }.should raise_error(SyntaxError)
-      -> { eval "->(x,x) {}" }.should raise_error(SyntaxError)
-      -> { eval "Proc.new { |x,x| }" }.should raise_error(SyntaxError)
+      -> { eval "lambda { |x,x| }" }.should.raise(SyntaxError)
+      -> { eval "->(x,x) {}" }.should.raise(SyntaxError)
+      -> { eval "Proc.new { |x,x| }" }.should.raise(SyntaxError)
     end
 
     it "accepts unnamed arguments" do
-      eval("lambda { |_,_| }").should be_an_instance_of(Proc)
-      eval("->(_,_) {}").should be_an_instance_of(Proc)
-      eval("Proc.new { |_,_| }").should be_an_instance_of(Proc)
+      lambda { |_,_| }.should.instance_of?(Proc) # rubocop:disable Style/Lambda
+      -> _,_ {}.should.instance_of?(Proc)
+      Proc.new { |_,_| }.should.instance_of?(Proc)
+    end
+  end
+
+  describe 'pre and post parameters' do
+    it "assigns nil to unassigned required arguments" do
+      proc { |a, *b, c, d| [a, b, c, d] }.call(1, 2).should == [1, [], 2, nil]
+    end
+
+    it "assigns elements to optional arguments" do
+      proc { |a=5, b=4, c=3| [a, b, c] }.call(1, 2).should == [1, 2, 3]
+    end
+
+    it "assigns elements to post arguments" do
+      proc { |a=5, b, c, d| [a, b, c, d] }.call(1, 2).should == [5, 1, 2, nil]
+    end
+
+    it "assigns elements to pre arguments" do
+      proc { |a, b, c, d=5| [a, b, c, d] }.call(1, 2).should == [1, 2, nil, 5]
+    end
+
+    it "assigns elements to pre and post arguments" do
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1               ).should == [1, 5, 6, nil, nil]
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1, 2            ).should == [1, 5, 6, 2, nil]
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1, 2, 3         ).should == [1, 5, 6, 2, 3]
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1, 2, 3, 4      ).should == [1, 2, 6, 3, 4]
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1, 2, 3, 4, 5   ).should == [1, 2, 3, 4, 5]
+      proc { |a, b=5, c=6, d, e| [a, b, c, d, e] }.call(1, 2, 3, 4, 5, 6).should == [1, 2, 3, 4, 5]
+    end
+
+    it "assigns elements to pre and post arguments when *rest is present" do
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1               ).should == [1, 5, 6, [], nil, nil]
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1, 2            ).should == [1, 5, 6, [], 2, nil]
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1, 2, 3         ).should == [1, 5, 6, [], 2, 3]
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1, 2, 3, 4      ).should == [1, 2, 6, [], 3, 4]
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1, 2, 3, 4, 5   ).should == [1, 2, 3, [], 4, 5]
+      proc { |a, b=5, c=6, *d, e, f| [a, b, c, d, e, f] }.call(1, 2, 3, 4, 5, 6).should == [1, 2, 3, [4], 5, 6]
     end
   end
 end
@@ -712,29 +787,29 @@ describe "Block-local variables" do
   end
 
   it "can not have the same name as one of the standard parameters" do
-    -> { eval "[1].each {|foo; foo| }" }.should raise_error(SyntaxError)
-    -> { eval "[1].each {|foo, bar; glark, bar| }" }.should raise_error(SyntaxError)
+    -> { eval "[1].each {|foo; foo| }" }.should.raise(SyntaxError)
+    -> { eval "[1].each {|foo, bar; glark, bar| }" }.should.raise(SyntaxError)
   end
 
   it "can not be prefixed with an asterisk" do
-    -> { eval "[1].each {|foo; *bar| }" }.should raise_error(SyntaxError)
+    -> { eval "[1].each {|foo; *bar| }" }.should.raise(SyntaxError)
     -> do
       eval "[1].each {|foo, bar; glark, *fnord| }"
-    end.should raise_error(SyntaxError)
+    end.should.raise(SyntaxError)
   end
 
   it "can not be prefixed with an ampersand" do
-    -> { eval "[1].each {|foo; &bar| }" }.should raise_error(SyntaxError)
+    -> { eval "[1].each {|foo; &bar| }" }.should.raise(SyntaxError)
     -> do
       eval "[1].each {|foo, bar; glark, &fnord| }"
-    end.should raise_error(SyntaxError)
+    end.should.raise(SyntaxError)
   end
 
   it "can not be assigned default values" do
-    -> { eval "[1].each {|foo; bar=1| }" }.should raise_error(SyntaxError)
+    -> { eval "[1].each {|foo; bar=1| }" }.should.raise(SyntaxError)
     -> do
       eval "[1].each {|foo, bar; glark, fnord=:fnord| }"
-    end.should raise_error(SyntaxError)
+    end.should.raise(SyntaxError)
   end
 
   it "need not be preceded by standard parameters" do
@@ -743,8 +818,8 @@ describe "Block-local variables" do
   end
 
   it "only allow a single semi-colon in the parameter list" do
-    -> { eval "[1].each {|foo; bar; glark| }" }.should raise_error(SyntaxError)
-    -> { eval "[1].each {|; bar; glark| }" }.should raise_error(SyntaxError)
+    -> { eval "[1].each {|foo; bar; glark| }" }.should.raise(SyntaxError)
+    -> { eval "[1].each {|; bar; glark| }" }.should.raise(SyntaxError)
   end
 
   it "override shadowed variables from the outer scope" do
@@ -769,21 +844,21 @@ describe "Block-local variables" do
   end
 
   it "are not automatically instantiated in the outer scope" do
-    defined?(glark).should be_nil
+    defined?(glark).should == nil
     [1].each {|;glark| 1}
-    defined?(glark).should be_nil
+    defined?(glark).should == nil
   end
 
   it "are automatically instantiated in the block" do
     [1].each do |;glark|
-      glark.should be_nil
+      glark.should == nil
     end
   end
 
   it "are visible in deeper scopes before initialization" do
     [1].each {|;glark|
       [1].each {
-        defined?(glark).should_not be_nil
+        defined?(glark).should_not == nil
         glark = 1
       }
       glark.should == 1
@@ -806,12 +881,18 @@ describe "Post-args" do
     end.call(1, 2, 3).should == [[], 1, 2, 3]
   end
 
-  it "are required" do
+  it "are required for a lambda" do
     -> {
       -> *a, b do
         [a, b]
       end.call
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
+  end
+
+  it "are assigned to nil when not enough arguments are given to a proc" do
+    proc do |a, *b, c|
+      [a, b, c]
+    end.call.should == [nil, [], nil]
   end
 
   describe "with required args" do
@@ -876,26 +957,27 @@ describe "Post-args" do
     end
 
     describe "with a circular argument reference" do
-      it "shadows an existing local with the same name as the argument" do
-        a = 1
-        -> {
-          @proc = eval "proc { |a=a| a }"
-        }.should complain(/circular argument reference/)
-        @proc.call.should == nil
+      ruby_version_is ""..."3.4" do
+        it "raises a SyntaxError if using the argument in its default value" do
+          a = 1
+          -> {
+            eval "proc { |a=a| a }"
+          }.should.raise(SyntaxError)
+        end
       end
 
-      it "shadows an existing method with the same name as the argument" do
-        def a; 1; end
-        -> {
-          @proc = eval "proc { |a=a| a }"
-        }.should complain(/circular argument reference/)
-        @proc.call.should == nil
+      ruby_version_is "3.4" do
+        it "is nil if using the argument in its default value" do
+          -> {
+            eval "proc { |a=a| a }.call"
+          }.call.should == nil
+        end
       end
+    end
 
-      it "calls an existing method with the same name as the argument if explicitly using ()" do
-        def a; 1; end
-        proc { |a=a()| a }.call.should == 1
-      end
+    it "calls an existing method with the same name as the argument if explicitly using ()" do
+      def a; 1; end
+      proc { |a=a()| a }.call.should == 1
     end
   end
 
@@ -913,3 +995,154 @@ describe "Post-args" do
     end
   end
 end
+
+# tested more thoroughly in language/delegation_spec.rb
+describe "Anonymous block forwarding" do
+  it "forwards blocks to other method that formally declares anonymous block" do
+    def b(&); c(&) end
+    def c(&); yield :non_null end
+
+    b { |c| c }.should == :non_null
+  end
+
+  it "requires the anonymous block parameter to be declared if directly passing a block" do
+    -> { eval "def a; b(&); end; def b; end" }.should.raise(SyntaxError)
+  end
+
+  it "works when it's the only declared parameter" do
+    def inner; yield end
+    def block_only(&); inner(&) end
+
+    block_only { 1 }.should == 1
+  end
+
+  it "works alongside positional parameters" do
+    def inner; yield end
+    def pos(arg1, &); inner(&) end
+
+    pos(:a) { 1 }.should == 1
+  end
+
+  it "works alongside positional arguments and splatted keyword arguments" do
+    def inner; yield end
+    def pos_kwrest(arg1, **kw, &); inner(&) end
+
+    pos_kwrest(:a, arg: 3) { 1 }.should == 1
+  end
+
+  it "works alongside positional arguments and disallowed keyword arguments" do
+    def inner; yield end
+    def no_kw(arg1, **nil, &); inner(&) end
+
+    no_kw(:a) { 1 }.should == 1
+  end
+
+  it "works alongside explicit keyword arguments" do
+    eval <<-EOF
+        def inner; yield end
+        def rest_kw(*a, kwarg: 1, &); inner(&) end
+        def kw(kwarg: 1, &); inner(&) end
+        def pos_kw_kwrest(arg1, kwarg: 1, **kw, &); inner(&) end
+        def pos_rkw(arg1, kwarg1:, &); inner(&) end
+        def all(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, &); inner(&) end
+        def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **kw, &); inner(&) end
+    EOF
+
+    rest_kw { 1 }.should == 1
+    kw { 1 }.should == 1
+    pos_kw_kwrest(:a) { 1 }.should == 1
+    pos_rkw(:a, kwarg1: 3) { 1 }.should == 1
+    all(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+    all_kwrest(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+  end
+end
+
+describe "`it` calls without arguments in a block" do
+  ruby_version_is ""..."3.4" do
+    it "emits a deprecation warning" do
+      -> {
+        eval "proc { it }"
+      }.should complain(/warning: `it` calls without arguments will refer to the first block param in Ruby 3.4; use it\(\) or self.it/)
+    end
+
+    it "emits a deprecation warning if numbered parameters are used" do
+      -> {
+        eval "proc { it; _1 }"
+      }.should complain(/warning: `it` calls without arguments will refer to the first block param in Ruby 3.4; use it\(\) or self.it/)
+    end
+
+    it "does not emit a deprecation warning when a block has parameters" do
+      -> { eval "proc { |a, b| it }" }.should_not complain
+      -> { eval "proc { |*rest| it }" }.should_not complain
+      -> { eval "proc { |*| it }" }.should_not complain
+      -> { eval "proc { |a:, b:| it }" }.should_not complain
+      -> { eval "proc { |**kw| it }" }.should_not complain
+      -> { eval "proc { |**| it }" }.should_not complain
+      -> { eval "proc { |&block| it }" }.should_not complain
+      -> { eval "proc { |&| it }" }.should_not complain
+      -> { eval "proc { || it }" }.should_not complain
+    end
+
+    it "does not emit a deprecation warning when `it` calls with arguments" do
+      -> { eval "proc { it(42) }" }.should_not complain
+      -> { eval "proc { it 42 }" }.should_not complain
+    end
+
+    it "does not emit a deprecation warning when `it` calls with a block" do
+      -> { eval "proc { it {} }" }.should_not complain
+    end
+
+    it "does not emit a deprecation warning when a local variable inside the block named `it` exists" do
+      -> { eval "proc { it = 42; it }" }.should_not complain
+    end
+
+    it "does not emit a deprecation warning when `it` calls with explicit empty arguments list" do
+      -> { eval "proc { it() }" }.should_not complain
+    end
+
+    it "calls the method `it` if defined" do
+      o = Object.new
+      def o.it
+        21
+      end
+      suppress_warning do
+        o.instance_eval("proc { it * 2 }").call(1).should == 42
+      end
+    end
+  end
+
+  ruby_version_is "4.1" do
+    it "works alongside disallowed block argument" do
+      no_block = eval <<-EOF
+        proc {|arg1, &nil| arg1}
+      EOF
+
+      no_block.call(:a).should == :a
+      -> { no_block.call(:a) {} }.should.raise(ArgumentError, 'no block accepted')
+    end
+  end
+end
+
+# Duplicates specs in language/it_parameter_spec.rb
+# Need them here to run on Ruby versions prior 3.4
+# TODO: remove when the minimal supported Ruby version is 3.4
+describe "if `it` is defined as a variable" do
+  it "treats `it` as a captured variable if defined outside of a block" do
+    it = 5
+    proc { it }.call(0).should == 5
+  end
+
+  it "treats `it` as a local variable if defined inside of a block" do
+    proc { it = 5; it }.call(0).should == 5
+  end
+end
+
+describe "Block-parameter destructuring" do
+  it "does not warn about unused inner names in verbose mode" do
+    -> {
+      eval <<~RUBY, binding, __FILE__, __LINE__ + 1
+        proc { |key, (val1, val2)| [key, val2] }
+      RUBY
+    }.should_not complain(verbose: true)
+  end
+end
diff --git a/spec/ruby/language/break_spec.rb b/spec/ruby/language/break_spec.rb
index 754d5d3c49..5c9b8060c3 100644
--- a/spec/ruby/language/break_spec.rb
+++ b/spec/ruby/language/break_spec.rb
@@ -52,29 +52,29 @@ describe "The break statement in a captured block" do
 
   describe "when the invocation of the scope creating the block is still active" do
     it "raises a LocalJumpError when invoking the block from the scope creating the block" do
-      -> { @program.break_in_method }.should raise_error(LocalJumpError)
+      -> { @program.break_in_method }.should.raise(LocalJumpError)
       ScratchPad.recorded.should == [:a, :xa, :d, :b]
     end
 
     it "raises a LocalJumpError when invoking the block from a method" do
-      -> { @program.break_in_nested_method }.should raise_error(LocalJumpError)
+      -> { @program.break_in_nested_method }.should.raise(LocalJumpError)
       ScratchPad.recorded.should == [:a, :xa, :cc, :aa, :b]
     end
 
     it "raises a LocalJumpError when yielding to the block" do
-      -> { @program.break_in_yielding_method }.should raise_error(LocalJumpError)
+      -> { @program.break_in_yielding_method }.should.raise(LocalJumpError)
       ScratchPad.recorded.should == [:a, :xa, :cc, :aa, :b]
     end
   end
 
   describe "from a scope that has returned" do
     it "raises a LocalJumpError when calling the block from a method" do
-      -> { @program.break_in_method_captured }.should raise_error(LocalJumpError)
+      -> { @program.break_in_method_captured }.should.raise(LocalJumpError)
       ScratchPad.recorded.should == [:a, :za, :xa, :zd, :zb]
     end
 
     it "raises a LocalJumpError when yielding to the block" do
-      -> { @program.break_in_yield_captured }.should raise_error(LocalJumpError)
+      -> { @program.break_in_yield_captured }.should.raise(LocalJumpError)
       ScratchPad.recorded.should == [:a, :za, :xa, :zd, :aa, :zb]
     end
   end
@@ -88,7 +88,7 @@ describe "The break statement in a captured block" do
           e
         end
       end
-      thread_with_break.value.should be_an_instance_of(LocalJumpError)
+      thread_with_break.value.should.instance_of?(LocalJumpError)
     end
   end
 end
@@ -252,6 +252,25 @@ describe "Break inside a while loop" do
   end
 end
 
+describe "The break statement in a method" do
+  it "is invalid and raises a SyntaxError" do
+    -> {
+      eval("def m; break; end")
+    }.should.raise(SyntaxError)
+  end
+end
+
+describe "The break statement in a module literal" do
+  it "is invalid and raises a SyntaxError" do
+    code = <<~RUBY
+      module BreakSpecs:ModuleWithBreak
+        break
+      end
+    RUBY
+
+    -> { eval(code) }.should.raise(SyntaxError)
+  end
+end
 
 # TODO: Rewrite all the specs from here to the end of the file in the style
 # above.
@@ -362,4 +381,22 @@ describe "Executing break from within a block" do
     bt2.three
     ScratchPad.recorded.should == [:two_ensure, :three_post, :three_ensure]
   end
+
+  it "works when passing through a super call" do
+    cls1 = Class.new { def foo; yield; end }
+    cls2 = Class.new(cls1) { def foo; super { break 1 }; end }
+
+    -> do
+      cls2.new.foo.should == 1
+    end.should_not.raise
+  end
+
+  it "raises LocalJumpError when converted into a proc during a super call" do
+    cls1 = Class.new { def foo(&b); b; end }
+    cls2 = Class.new(cls1) { def foo; super { break 1 }.call; end }
+
+    -> do
+      cls2.new.foo
+    end.should.raise(LocalJumpError)
+  end
 end
diff --git a/spec/ruby/language/case_spec.rb b/spec/ruby/language/case_spec.rb
index 1475e20f75..41881bf20a 100644
--- a/spec/ruby/language/case_spec.rb
+++ b/spec/ruby/language/case_spec.rb
@@ -27,6 +27,41 @@ describe "The 'case'-construct" do
     @calls.should == [:foo, :bar]
   end
 
+  it "matches an Integer literal whose value does not fit in a 32-bit int" do
+    big = 10_000_000_000
+    case big
+    when 10_000_000_000; true
+    else                 false
+    end.should == true
+
+    case -3_000_000_000
+    when -3_000_000_000; true
+    else                 false
+    end.should == true
+  end
+
+  it "matches an arbitrary-precision Integer literal" do
+    huge = 1267650600228229401496703205376
+    case huge
+    when 1267650600228229401496703205376; true
+    else                                  false
+    end.should == true
+  end
+
+  it "dispatches correctly with mixed small and large Integer literals" do
+    pick = -> x {
+      case x
+      when 1267650600228229401496703205376 then :beyond_long
+      when 10_000_000_000                  then :beyond_int
+      when 1                               then :fits_int
+      else                                      :other
+      end
+    }
+
+    [1267650600228229401496703205376, 10_000_000_000, 1, :nope].map(&pick).should ==
+      [:beyond_long, :beyond_int, :fits_int, :other]
+  end
+
   it "evaluates the body of the when clause whose range expression includes the case target expression" do
     case 5
     when 21..30; false
@@ -94,38 +129,38 @@ describe "The 'case'-construct" do
   it "tests with matching regexps and sets $~ and captures" do
     case "foo42"
     when /oo(\d+)/
-      $~.should be_kind_of(MatchData)
+      $~.should.is_a?(MatchData)
       $1.should == "42"
     else
       flunk
     end
-    $~.should be_kind_of(MatchData)
+    $~.should.is_a?(MatchData)
     $1.should == "42"
   end
 
-  it "tests with a regexp interpolated within another regexp" do
+  it "tests with a string interpolated in a regexp" do
     digits = '\d+'
     case "foo44"
     when /oo(#{digits})/
-      $~.should be_kind_of(MatchData)
+      $~.should.is_a?(MatchData)
       $1.should == "44"
     else
       flunk
     end
-    $~.should be_kind_of(MatchData)
+    $~.should.is_a?(MatchData)
     $1.should == "44"
   end
 
-  it "tests with a string interpolated in a regexp" do
+  it "tests with a regexp interpolated within another regexp" do
     digits_regexp = /\d+/
     case "foo43"
     when /oo(#{digits_regexp})/
-      $~.should be_kind_of(MatchData)
+      $~.should.is_a?(MatchData)
       $1.should == "43"
     else
       flunk
     end
-    $~.should be_kind_of(MatchData)
+    $~.should.is_a?(MatchData)
     $1.should == "43"
   end
 
@@ -156,6 +191,15 @@ describe "The 'case'-construct" do
     end.should == "foo"
   end
 
+  it "tests an empty array" do
+    case []
+    when []
+      'foo'
+    else
+      'bar'
+    end.should == 'foo'
+  end
+
   it "expands arrays to lists of values" do
     case 'z'
     when *['a', 'b', 'c', 'd']
@@ -259,7 +303,7 @@ describe "The 'case'-construct" do
         true
       end
       CODE
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 
   it "raises a SyntaxError when 'else' is used before a 'when' was given" do
@@ -271,7 +315,7 @@ describe "The 'case'-construct" do
       when 4; false
       end
       CODE
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 
   it "supports nested case statements" do
@@ -320,49 +364,6 @@ describe "The 'case'-construct" do
       100
     end.should == 100
   end
-end
-
-describe "The 'case'-construct with no target expression" do
-  it "evaluates the body of the first clause when at least one of its condition expressions is true" do
-    case
-    when true, false; 'foo'
-    end.should == 'foo'
-  end
-
-  it "evaluates the body of the first when clause that is not false/nil" do
-    case
-    when false; 'foo'
-    when 2; 'bar'
-    when 1 == 1; 'baz'
-    end.should == 'bar'
-
-    case
-    when false; 'foo'
-    when nil; 'foo'
-    when 1 == 1; 'bar'
-    end.should == 'bar'
-  end
-
-  it "evaluates the body of the else clause if all when clauses are false/nil" do
-    case
-    when false; 'foo'
-    when nil; 'foo'
-    when 1 == 2; 'bar'
-    else 'baz'
-    end.should == 'baz'
-  end
-
-  it "evaluates multiple conditional expressions as a boolean disjunction" do
-    case
-    when true, false; 'foo'
-    else 'bar'
-    end.should == 'foo'
-
-    case
-    when false, true; 'foo'
-    else 'bar'
-    end.should == 'foo'
-  end
 
   it "evaluates true as only 'true' when true is the first clause" do
     case 1
@@ -424,4 +425,120 @@ describe "The 'case'-construct with no target expression" do
       :called
     end.should == :called
   end
+
+  it "only matches last value in complex expressions within ()" do
+    case 'a'
+    when ('a'; 'b')
+      :wrong_called
+    when ('b'; 'a')
+      :called
+    end.should == :called
+  end
+
+  it "supports declaring variables in the case target expression" do
+    def test(v)
+      case new_variable_in_expression = v
+      when true
+        # This extra block is a test that `new_variable_in_expression` is declared outside of it and not inside
+        self.then { new_variable_in_expression }
+      else
+        # Same
+        self.then { new_variable_in_expression.casecmp?("foo") }
+      end
+    end
+
+    self.test("bar").should == false
+    self.test(true).should == true
+  end
+
+  ruby_version_is ""..."3.4" do
+    it "warns if there are identical when clauses" do
+      -> {
+        eval <<~RUBY
+          case 1
+          when 2
+            :foo
+          when 2
+            :bar
+          end
+        RUBY
+      }.should complain(/warning: (duplicated .when' clause with line \d+ is ignored|'when' clause on line \d+ duplicates 'when' clause on line \d+ and is ignored)/, verbose: true)
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "warns if there are identical when clauses" do
+      -> {
+        eval <<~RUBY
+          case 1
+          when 2
+            :foo
+          when 2
+            :bar
+          end
+        RUBY
+      }.should complain(/warning: 'when' clause on line \d+ duplicates 'when' clause on line \d+ and is ignored/, verbose: true)
+    end
+  end
+end
+
+describe "The 'case'-construct with no target expression" do
+  it "evaluates the body of the first clause when at least one of its condition expressions is true" do
+    case
+    when true, false; 'foo'
+    end.should == 'foo'
+  end
+
+  it "evaluates the body of the first when clause that is not false/nil" do
+    case
+    when false; 'foo'
+    when 2; 'bar'
+    when 1 == 1; 'baz'
+    end.should == 'bar'
+
+    case
+    when false; 'foo'
+    when nil; 'foo'
+    when 1 == 1; 'bar'
+    end.should == 'bar'
+  end
+
+  it "evaluates the body of the else clause if all when clauses are false/nil" do
+    case
+    when false; 'foo'
+    when nil; 'foo'
+    when 1 == 2; 'bar'
+    else 'baz'
+    end.should == 'baz'
+  end
+
+  it "evaluates multiple conditional expressions as a boolean disjunction" do
+    case
+    when true, false; 'foo'
+    else 'bar'
+    end.should == 'foo'
+
+    case
+    when false, true; 'foo'
+    else 'bar'
+    end.should == 'foo'
+  end
+
+  # Homogeneous cases are often optimized to avoid === using a jump table, and should be tested separately.
+  # See https://github.com/jruby/jruby/issues/6440
+  it "handles homogeneous cases" do
+    case
+    when 1; 'foo'
+    when 2; 'bar'
+    end.should == 'foo'
+  end
+
+  it "expands arrays to lists of values" do
+    case
+    when *[false]
+      "foo"
+    when *[true]
+      "bar"
+    end.should == "bar"
+  end
 end
diff --git a/spec/ruby/language/class_spec.rb b/spec/ruby/language/class_spec.rb
index 88b7a6a74f..7ea4857514 100644
--- a/spec/ruby/language/class_spec.rb
+++ b/spec/ruby/language/class_spec.rb
@@ -10,19 +10,32 @@ end
 describe "The class keyword" do
   it "creates a new class with semicolon" do
     class ClassSpecsKeywordWithSemicolon; end
-    ClassSpecsKeywordWithSemicolon.should be_an_instance_of(Class)
+    ClassSpecsKeywordWithSemicolon.should.instance_of?(Class)
   end
 
   it "does not raise a SyntaxError when opening a class without a semicolon" do
     eval "class ClassSpecsKeywordWithoutSemicolon end"
-    ClassSpecsKeywordWithoutSemicolon.should be_an_instance_of(Class)
+    ClassSpecsKeywordWithoutSemicolon.should.instance_of?(Class)
+  end
+
+  it "can redefine a class when called from a block" do
+    ClassSpecs::DEFINE_CLASS.call
+    A.should.instance_of?(Class)
+
+    Object.send(:remove_const, :A)
+    defined?(A).should == nil
+
+    ClassSpecs::DEFINE_CLASS.call
+    A.should.instance_of?(Class)
+  ensure
+    Object.send(:remove_const, :A) if defined?(::A)
   end
 end
 
 describe "A class definition" do
   it "creates a new class" do
-    ClassSpecs::A.should be_kind_of(Class)
-    ClassSpecs::A.new.should be_kind_of(ClassSpecs::A)
+    ClassSpecs::A.should.is_a?(Class)
+    ClassSpecs::A.new.should.is_a?(ClassSpecs::A)
   end
 
   it "has no class variables" do
@@ -33,7 +46,14 @@ describe "A class definition" do
     -> {
       class ClassSpecsNumber
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError, /\AClassSpecsNumber is not a class/)
+  end
+
+  it "raises TypeError if constant given as class name exists and is a Module but not a Class" do
+    -> {
+      class ClassSpecs
+      end
+    }.should.raise(TypeError, /\AClassSpecs is not a class/)
   end
 
   # test case known to be detecting bugs (JRuby, MRI)
@@ -41,19 +61,19 @@ describe "A class definition" do
     -> {
       class nil::Foo
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises TypeError if any constant qualifying the class is not a Module" do
     -> {
       class ClassSpecs::Number::MyClass
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
 
     -> {
       class ClassSpecsNumber::MyClass
       end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "inherits from Object by default" do
@@ -67,7 +87,7 @@ describe "A class definition" do
       -> {
         class SuperclassResetToSubclass < M
         end
-      }.should raise_error(TypeError, /superclass mismatch/)
+      }.should.raise(TypeError, /superclass mismatch/)
     end
   end
 
@@ -80,7 +100,7 @@ describe "A class definition" do
       -> {
         class SuperclassReopenedBasicObject < BasicObject
         end
-      }.should raise_error(TypeError, /superclass mismatch/)
+      }.should.raise(TypeError, /superclass mismatch/)
       SuperclassReopenedBasicObject.superclass.should == A
     end
   end
@@ -95,7 +115,7 @@ describe "A class definition" do
       -> {
         class SuperclassReopenedObject < Object
         end
-      }.should raise_error(TypeError, /superclass mismatch/)
+      }.should.raise(TypeError, /superclass mismatch/)
       SuperclassReopenedObject.superclass.should == A
     end
   end
@@ -120,7 +140,7 @@ describe "A class definition" do
       -> {
         class NoSuperclassSet < String
         end
-      }.should raise_error(TypeError, /superclass mismatch/)
+      }.should.raise(TypeError, /superclass mismatch/)
     end
   end
 
@@ -129,7 +149,7 @@ describe "A class definition" do
 
     -> {
       class ShouldNotWork < self; end
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "first evaluates the superclass before checking if the class already exists" do
@@ -148,7 +168,7 @@ describe "A class definition" do
   it "raises a TypeError if inheriting from a metaclass" do
     obj = mock("metaclass super")
     meta = obj.singleton_class
-    -> { class ClassSpecs::MetaclassSuper < meta; end }.should raise_error(TypeError)
+    -> { class ClassSpecs::MetaclassSuper < meta; end }.should.raise(TypeError)
   end
 
   it "allows the declaration of class variables in the body" do
@@ -157,7 +177,7 @@ describe "A class definition" do
   end
 
   it "stores instance variables defined in the class body in the class object" do
-    ClassSpecs.string_instance_variables(ClassSpecs::B).should include("@ivar")
+    ClassSpecs.string_instance_variables(ClassSpecs::B).should.include?("@ivar")
     ClassSpecs::B.instance_variable_get(:@ivar).should == :ivar
   end
 
@@ -169,9 +189,9 @@ describe "A class definition" do
   end
 
   it "allows the definition of class-level instance variables in a class method" do
-    ClassSpecs.string_instance_variables(ClassSpecs::C).should_not include("@civ")
+    ClassSpecs.string_instance_variables(ClassSpecs::C).should_not.include?("@civ")
     ClassSpecs::C.make_class_instance_variable
-    ClassSpecs.string_instance_variables(ClassSpecs::C).should include("@civ")
+    ClassSpecs.string_instance_variables(ClassSpecs::C).should.include?("@civ")
     ClassSpecs::C.remove_instance_variable :@civ
   end
 
@@ -258,13 +278,16 @@ describe "A class definition" do
 
       AnonWithConstant.name.should == 'AnonWithConstant'
       klass.get_class_name.should == 'AnonWithConstant'
+    ensure
+      Object.send(:remove_const, :AnonWithConstant)
     end
   end
 end
 
 describe "An outer class definition" do
   it "contains the inner classes" do
-    ClassSpecs::Container.constants.should include(:A, :B)
+    ClassSpecs::Container.constants.should.include?(:A)
+    ClassSpecs::Container.constants.should.include?(:B)
   end
 end
 
@@ -282,15 +305,23 @@ describe "A class definition extending an object (sclass)" do
           end
         end
       CODE
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
-  ruby_version_is ""..."3.0" do
-    it "allows accessing the block of the original scope" do
-      suppress_warning do
-        ClassSpecs.sclass_with_block { 123 }.should == 123
-      end
-    end
+  it "raises a TypeError when trying to extend non-Class" do
+    error_msg = /superclass must be a.* Class/
+    -> { class TestClass < "";              end }.should.raise(TypeError, error_msg)
+    -> { class TestClass < 1;               end }.should.raise(TypeError, error_msg)
+    -> { class TestClass < :symbol;         end }.should.raise(TypeError, error_msg)
+    -> { class TestClass < mock('o');       end }.should.raise(TypeError, error_msg)
+    -> { class TestClass < Module.new;      end }.should.raise(TypeError, error_msg)
+    -> { class TestClass < BasicObject.new; end }.should.raise(TypeError, error_msg)
+  end
+
+  it "does not allow accessing the block of the original scope" do
+    -> {
+      ClassSpecs.sclass_with_block { 123 }
+    }.should.raise(SyntaxError)
   end
 
   it "can use return to cause the enclosing method to return" do
@@ -310,11 +341,11 @@ describe "Reopening a class" do
   end
 
   it "raises a TypeError when superclasses mismatch" do
-    -> { class ClassSpecs::A < Array; end }.should raise_error(TypeError)
+    -> { class ClassSpecs::A < Array; end }.should.raise(TypeError)
   end
 
   it "adds new methods to subclasses" do
-    -> { ClassSpecs::M.m }.should raise_error(NoMethodError)
+    -> { ClassSpecs::M.m }.should.raise(NoMethodError)
     class ClassSpecs::L
       def self.m
         1
@@ -323,6 +354,39 @@ describe "Reopening a class" do
     ClassSpecs::M.m.should == 1
     ClassSpecs::L.singleton_class.send(:remove_method, :m)
   end
+
+  it "does not reopen a class included in Object" do
+    ruby_exe(<<~RUBY).should == "false"
+      module IncludedInObject
+        class IncludedClass
+        end
+      end
+      class Object
+        include IncludedInObject
+      end
+      class IncludedClass
+      end
+      print IncludedInObject::IncludedClass == Object::IncludedClass
+    RUBY
+  end
+
+  it "does not reopen a class included in non-Object modules" do
+    ruby_exe(<<~RUBY).should == "false/false"
+      module Included
+        module IncludedClass; end
+      end
+      module M
+        include Included
+        module IncludedClass; end
+      end
+      class C
+        include Included
+        module IncludedClass; end
+      end
+      print Included::IncludedClass == M::IncludedClass, "/",
+            Included::IncludedClass == C::IncludedClass
+    RUBY
+  end
 end
 
 describe "class provides hooks" do
diff --git a/spec/ruby/language/class_variable_spec.rb b/spec/ruby/language/class_variable_spec.rb
index dffab47a6b..84a7684c6d 100644
--- a/spec/ruby/language/class_variable_spec.rb
+++ b/spec/ruby/language/class_variable_spec.rb
@@ -30,19 +30,19 @@ describe "A class variable defined in a module" do
   end
 
   it "is not defined in these classes" do
-    ClassVariablesSpec::ClassC.cvar_defined?.should be_false
+    ClassVariablesSpec::ClassC.cvar_defined?.should == false
   end
 
   it "is only updated in the module a method defined in the module is used" do
     ClassVariablesSpec::ClassC.cvar_m = "new value"
     ClassVariablesSpec::ClassC.cvar_m.should == "new value"
 
-    ClassVariablesSpec::ClassC.cvar_defined?.should be_false
+    ClassVariablesSpec::ClassC.cvar_defined?.should == false
   end
 
   it "is updated in the class when a Method defined in the class is used" do
     ClassVariablesSpec::ClassC.cvar_c = "new value"
-    ClassVariablesSpec::ClassC.cvar_defined?.should be_true
+    ClassVariablesSpec::ClassC.cvar_defined?.should == true
   end
 
   it "can be accessed inside the class using the module methods" do
@@ -55,11 +55,11 @@ describe "A class variable defined in a module" do
   end
 
   it "is defined in the extended module" do
-    ClassVariablesSpec::ModuleN.class_variable_defined?(:@@cvar_n).should be_true
+    ClassVariablesSpec::ModuleN.class_variable_defined?(:@@cvar_n).should == true
   end
 
   it "is not defined in the extending module" do
-    ClassVariablesSpec::ModuleO.class_variable_defined?(:@@cvar_n).should be_false
+    ClassVariablesSpec::ModuleO.class_variable_defined?(:@@cvar_n).should == false
   end
 end
 
@@ -70,15 +70,45 @@ describe 'A class variable definition' do
     c = Class.new(b)
     b.class_variable_set(:@@cv, :value)
 
-    -> { a.class_variable_get(:@@cv) }.should raise_error(NameError)
+    -> { a.class_variable_get(:@@cv) }.should.raise(NameError)
     b.class_variable_get(:@@cv).should == :value
     c.class_variable_get(:@@cv).should == :value
 
     # updates the same variable
     c.class_variable_set(:@@cv, :next)
 
-    -> { a.class_variable_get(:@@cv) }.should raise_error(NameError)
+    -> { a.class_variable_get(:@@cv) }.should.raise(NameError)
     b.class_variable_get(:@@cv).should == :next
     c.class_variable_get(:@@cv).should == :next
   end
 end
+
+describe 'Accessing a class variable' do
+  it "raises a RuntimeError when accessed from the toplevel scope (not in some module or class)" do
+    -> {
+      eval "@@cvar_toplevel1"
+    }.should.raise(RuntimeError, 'class variable access from toplevel')
+    -> {
+      eval "@@cvar_toplevel2 = 2"
+    }.should.raise(RuntimeError, 'class variable access from toplevel')
+  end
+
+  it "does not raise an error when checking if defined from the toplevel scope" do
+    -> {
+      eval "defined?(@@cvar_toplevel1)"
+    }.should_not.raise
+  end
+
+  it "raises a RuntimeError when a class variable is overtaken in an ancestor class" do
+    parent = Class.new()
+    subclass = Class.new(parent)
+    subclass.class_variable_set(:@@cvar_overtaken, :subclass)
+    parent.class_variable_set(:@@cvar_overtaken, :parent)
+
+    -> {
+      subclass.class_variable_get(:@@cvar_overtaken)
+    }.should.raise(RuntimeError, /class variable @@cvar_overtaken of .+ is overtaken by .+/)
+
+    parent.class_variable_get(:@@cvar_overtaken).should == :parent
+  end
+end
diff --git a/spec/ruby/language/comment_spec.rb b/spec/ruby/language/comment_spec.rb
new file mode 100644
index 0000000000..dd788e681c
--- /dev/null
+++ b/spec/ruby/language/comment_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../spec_helper'
+
+describe "The comment" do
+  it "can be placed between fluent dot now" do
+    code = <<~CODE
+      10
+        # some comment
+        .to_s
+      CODE
+
+    eval(code).should == '10'
+  end
+end
diff --git a/spec/ruby/language/constants_spec.rb b/spec/ruby/language/constants_spec.rb
index c4cf940cba..0880230a36 100644
--- a/spec/ruby/language/constants_spec.rb
+++ b/spec/ruby/language/constants_spec.rb
@@ -51,8 +51,8 @@ describe "Literal (A::X) constant resolution" do
     it "does not search the singleton class of the class or module" do
       -> do
         ConstantSpecs::ContainerA::ChildA::CS_CONST14
-      end.should raise_error(NameError)
-      -> { ConstantSpecs::CS_CONST14 }.should raise_error(NameError)
+      end.should.raise(NameError)
+      -> { ConstantSpecs::CS_CONST14 }.should.raise(NameError)
     end
   end
 
@@ -72,39 +72,60 @@ describe "Literal (A::X) constant resolution" do
 
       ConstantSpecs::ModuleA::CS_CONST101 = :const101_5
       ConstantSpecs::ModuleA::CS_CONST101.should == :const101_5
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST101)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST101)
+      ConstantSpecs::ContainerB.send(:remove_const, :CS_CONST101)
+      ConstantSpecs::ContainerB::ChildB.send(:remove_const, :CS_CONST101)
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST101)
     end
 
     it "searches a module included in the immediate class before the superclass" do
       ConstantSpecs::ParentB::CS_CONST102 = :const102_1
       ConstantSpecs::ModuleF::CS_CONST102 = :const102_2
       ConstantSpecs::ContainerB::ChildB::CS_CONST102.should == :const102_2
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST102)
+      ConstantSpecs::ModuleF.send(:remove_const, :CS_CONST102)
     end
 
     it "searches the superclass before a module included in the superclass" do
       ConstantSpecs::ModuleE::CS_CONST103 = :const103_1
       ConstantSpecs::ParentB::CS_CONST103 = :const103_2
       ConstantSpecs::ContainerB::ChildB::CS_CONST103.should == :const103_2
+    ensure
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST103)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST103)
     end
 
     it "searches a module included in the superclass" do
       ConstantSpecs::ModuleA::CS_CONST104 = :const104_1
       ConstantSpecs::ModuleE::CS_CONST104 = :const104_2
       ConstantSpecs::ContainerB::ChildB::CS_CONST104.should == :const104_2
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST104)
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST104)
     end
 
     it "searches the superclass chain" do
       ConstantSpecs::ModuleA::CS_CONST105 = :const105
       ConstantSpecs::ContainerB::ChildB::CS_CONST105.should == :const105
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST105)
     end
 
     it "searches Object if no class or module qualifier is given" do
       CS_CONST106 = :const106
       CS_CONST106.should == :const106
+    ensure
+      Object.send(:remove_const, :CS_CONST106)
     end
 
     it "searches Object if a toplevel qualifier (::X) is given" do
       ::CS_CONST107 = :const107
       ::CS_CONST107.should == :const107
+    ensure
+      Object.send(:remove_const, :CS_CONST107)
     end
 
     it "does not search the singleton class of the class or module" do
@@ -114,7 +135,7 @@ describe "Literal (A::X) constant resolution" do
 
       -> do
         ConstantSpecs::ContainerB::ChildB::CS_CONST108
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
 
       module ConstantSpecs
         class << self
@@ -122,7 +143,10 @@ describe "Literal (A::X) constant resolution" do
         end
       end
 
-      -> { ConstantSpecs::CS_CONST108 }.should raise_error(NameError)
+      -> { ConstantSpecs::CS_CONST108 }.should.raise(NameError)
+    ensure
+      ConstantSpecs::ContainerB::ChildB.singleton_class.send(:remove_const, :CS_CONST108)
+      ConstantSpecs.singleton_class.send(:remove_const, :CS_CONST108)
     end
 
     it "returns the updated value when a constant is reassigned" do
@@ -133,25 +157,53 @@ describe "Literal (A::X) constant resolution" do
         ConstantSpecs::ClassB::CS_CONST109 = :const109_2
       }.should complain(/already initialized constant/)
       ConstantSpecs::ClassB::CS_CONST109.should == :const109_2
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST109)
     end
 
-    it "evaluates the right hand side before evaluating a constant path" do
+    it "evaluates left-to-right" do
       mod = Module.new
 
       mod.module_eval <<-EOC
-        ConstantSpecsRHS::B = begin
-          module ConstantSpecsRHS; end
-
-          "hello"
-        end
+        order = []
+        ConstantSpecsRHS = Module.new
+        (order << :lhs; ConstantSpecsRHS)::B = (order << :rhs)
       EOC
 
-      mod::ConstantSpecsRHS::B.should == 'hello'
+      mod::ConstantSpecsRHS::B.should == [:lhs, :rhs]
     end
   end
 
   it "raises a NameError if no constant is defined in the search path" do
-    -> { ConstantSpecs::ParentA::CS_CONSTX }.should raise_error(NameError)
+    -> { ConstantSpecs::ParentA::CS_CONSTX }.should.raise(NameError)
+  end
+
+  it "uses the module or class #name to craft the error message" do
+    mod = Module.new do
+      def self.name
+        "ModuleName"
+      end
+
+      def self.inspect
+        "<unusable info>"
+      end
+    end
+
+    -> { mod::DOES_NOT_EXIST }.should.raise(NameError, /uninitialized constant ModuleName::DOES_NOT_EXIST/)
+  end
+
+  it "uses the module or class #inspect to craft the error message if they are anonymous" do
+    mod = Module.new do
+      def self.name
+        nil
+      end
+
+      def self.inspect
+        "<unusable info>"
+      end
+    end
+
+    -> { mod::DOES_NOT_EXIST }.should.raise(NameError, /uninitialized constant <unusable info>::DOES_NOT_EXIST/)
   end
 
   it "sends #const_missing to the original class or module scope" do
@@ -163,10 +215,10 @@ describe "Literal (A::X) constant resolution" do
   end
 
   it "raises a TypeError if a non-class or non-module qualifier is given" do
-    -> { CS_CONST1::CS_CONST }.should raise_error(TypeError)
-    -> { 1::CS_CONST         }.should raise_error(TypeError)
-    -> { "mod"::CS_CONST     }.should raise_error(TypeError)
-    -> { false::CS_CONST     }.should raise_error(TypeError)
+    -> { CS_CONST1::CS_CONST }.should.raise(TypeError)
+    -> { 1::CS_CONST         }.should.raise(TypeError)
+    -> { "mod"::CS_CONST     }.should.raise(TypeError)
+    -> { false::CS_CONST     }.should.raise(TypeError)
   end
 end
 
@@ -212,7 +264,7 @@ describe "Constant resolution within methods" do
     end
 
     it "does not search the lexical scope of the caller" do
-      -> { ConstantSpecs::ClassA.const16 }.should raise_error(NameError)
+      -> { ConstantSpecs::ClassA.const16 }.should.raise(NameError)
     end
 
     it "searches the lexical scope of a block" do
@@ -227,7 +279,7 @@ describe "Constant resolution within methods" do
     it "does not search the lexical scope of qualifying modules" do
       -> do
         ConstantSpecs::ContainerA::ChildA.const23
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
   end
 
@@ -248,6 +300,12 @@ describe "Constant resolution within methods" do
       ConstantSpecs::ClassB.new.const201.should == :const201_2
       ConstantSpecs::ParentB.new.const201.should == :const201_3
       ConstantSpecs::ContainerB::ChildB.new.const201.should == :const201_5
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST201)
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST201)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST201)
+      ConstantSpecs::ContainerB.send(:remove_const, :CS_CONST201)
+      ConstantSpecs::ContainerB::ChildB.send(:remove_const, :CS_CONST201)
     end
 
     it "searches a module included in the immediate class before the superclass" do
@@ -256,6 +314,9 @@ describe "Constant resolution within methods" do
 
       ConstantSpecs::ContainerB::ChildB.const202.should == :const202_1
       ConstantSpecs::ContainerB::ChildB.new.const202.should == :const202_1
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST202)
+      ConstantSpecs::ContainerB::ChildB.send(:remove_const, :CS_CONST202)
     end
 
     it "searches the superclass before a module included in the superclass" do
@@ -264,6 +325,9 @@ describe "Constant resolution within methods" do
 
       ConstantSpecs::ContainerB::ChildB.const203.should == :const203_1
       ConstantSpecs::ContainerB::ChildB.new.const203.should == :const203_1
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST203)
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST203)
     end
 
     it "searches a module included in the superclass" do
@@ -272,6 +336,9 @@ describe "Constant resolution within methods" do
 
       ConstantSpecs::ContainerB::ChildB.const204.should == :const204_1
       ConstantSpecs::ContainerB::ChildB.new.const204.should == :const204_1
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST204)
+      ConstantSpecs::ModuleE.send(:remove_const, :CS_CONST204)
     end
 
     it "searches the superclass chain" do
@@ -279,6 +346,8 @@ describe "Constant resolution within methods" do
 
       ConstantSpecs::ContainerB::ChildB.const205.should == :const205
       ConstantSpecs::ContainerB::ChildB.new.const205.should == :const205
+    ensure
+      ConstantSpecs::ModuleA.send(:remove_const, :CS_CONST205)
     end
 
     it "searches the lexical scope of the method not the receiver's immediate class" do
@@ -290,6 +359,9 @@ describe "Constant resolution within methods" do
       end
 
       ConstantSpecs::ContainerB::ChildB.const206.should == :const206_1
+    ensure
+      ConstantSpecs::ContainerB::ChildB.send(:remove_const, :CS_CONST206)
+      ConstantSpecs::ContainerB::ChildB.singleton_class.send(:remove_const, :CS_CONST206)
     end
 
     it "searches the lexical scope of a singleton method" do
@@ -297,12 +369,17 @@ describe "Constant resolution within methods" do
       ConstantSpecs::ClassB::CS_CONST207 = :const207_2
 
       ConstantSpecs::CS_CONST208.const207.should == :const207_1
+    ensure
+      ConstantSpecs.send(:remove_const, :CS_CONST207)
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST207)
     end
 
     it "does not search the lexical scope of the caller" do
       ConstantSpecs::ClassB::CS_CONST209 = :const209
 
-      -> { ConstantSpecs::ClassB.const209 }.should raise_error(NameError)
+      -> { ConstantSpecs::ClassB.const209 }.should.raise(NameError)
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST209)
     end
 
     it "searches the lexical scope of a block" do
@@ -310,6 +387,9 @@ describe "Constant resolution within methods" do
       ConstantSpecs::ParentB::CS_CONST210 = :const210_2
 
       ConstantSpecs::ClassB.const210.should == :const210_1
+    ensure
+      ConstantSpecs::ClassB.send(:remove_const, :CS_CONST210)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST210)
     end
 
     it "searches Object as a lexical scope only if Object is explicitly opened" do
@@ -320,6 +400,11 @@ describe "Constant resolution within methods" do
       Object::CS_CONST212 = :const212_2
       ConstantSpecs::ParentB::CS_CONST212 = :const212_1
       ConstantSpecs::ContainerB::ChildB.const212.should == :const212_1
+    ensure
+      Object.send(:remove_const, :CS_CONST211)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST211)
+      Object.send(:remove_const, :CS_CONST212)
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST212)
     end
 
     it "returns the updated value when a constant is reassigned" do
@@ -332,6 +417,8 @@ describe "Constant resolution within methods" do
       }.should complain(/already initialized constant/)
       ConstantSpecs::ContainerB::ChildB.const213.should == :const213_2
       ConstantSpecs::ContainerB::ChildB.new.const213.should == :const213_2
+    ensure
+      ConstantSpecs::ParentB.send(:remove_const, :CS_CONST213)
     end
 
     it "does not search the lexical scope of qualifying modules" do
@@ -339,64 +426,20 @@ describe "Constant resolution within methods" do
 
       -> do
         ConstantSpecs::ContainerB::ChildB.const214
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
+    ensure
+      ConstantSpecs::ContainerB.send(:remove_const, :CS_CONST214)
     end
   end
 
   it "raises a NameError if no constant is defined in the search path" do
-    -> { ConstantSpecs::ParentA.constx }.should raise_error(NameError)
+    -> { ConstantSpecs::ParentA.constx }.should.raise(NameError)
   end
 
   it "sends #const_missing to the original class or module scope" do
     ConstantSpecs::ClassA.constx.should == :CS_CONSTX
     ConstantSpecs::ClassA.new.constx.should == :CS_CONSTX
   end
-
-  describe "with ||=" do
-    it "assigns a scoped constant if previously undefined" do
-      ConstantSpecs.should_not have_constant(:OpAssignUndefined)
-      module ConstantSpecs
-        OpAssignUndefined ||= 42
-      end
-      ConstantSpecs::OpAssignUndefined.should == 42
-      ConstantSpecs::OpAssignUndefinedOutside ||= 42
-      ConstantSpecs::OpAssignUndefinedOutside.should == 42
-      ConstantSpecs.send(:remove_const, :OpAssignUndefined)
-      ConstantSpecs.send(:remove_const, :OpAssignUndefinedOutside)
-    end
-
-    it "assigns a global constant if previously undefined" do
-      OpAssignGlobalUndefined ||= 42
-      ::OpAssignGlobalUndefinedExplicitScope ||= 42
-      OpAssignGlobalUndefined.should == 42
-      ::OpAssignGlobalUndefinedExplicitScope.should == 42
-      Object.send :remove_const, :OpAssignGlobalUndefined
-      Object.send :remove_const, :OpAssignGlobalUndefinedExplicitScope
-    end
-
-  end
-
-  describe "with &&=" do
-    it "re-assigns a scoped constant if already true" do
-      module ConstantSpecs
-        OpAssignTrue = true
-      end
-      suppress_warning do
-        ConstantSpecs::OpAssignTrue &&= 1
-      end
-      ConstantSpecs::OpAssignTrue.should == 1
-      ConstantSpecs.send :remove_const, :OpAssignTrue
-    end
-
-    it "leaves scoped constant if not true" do
-      module ConstantSpecs
-        OpAssignFalse = false
-      end
-      ConstantSpecs::OpAssignFalse &&= 1
-      ConstantSpecs::OpAssignFalse.should == false
-      ConstantSpecs.send :remove_const, :OpAssignFalse
-    end
-  end
 end
 
 describe "Constant resolution within a singleton class (class << obj)" do
@@ -413,7 +456,7 @@ describe "Constant resolution within a singleton class (class << obj)" do
   it "uses its own namespace for nested modules" do
     a = ConstantSpecs::CS_SINGLETON3[0].x
     b = ConstantSpecs::CS_SINGLETON3[1].x
-    a.should_not equal(b)
+    a.should_not.equal?(b)
   end
 
   it "allows nested modules to have proper resolution" do
@@ -425,23 +468,13 @@ end
 
 describe "top-level constant lookup" do
   context "on a class" do
-    ruby_version_is "" ... "2.5" do
-      it "searches Object successfully after searching other scopes" do
-        -> {
-          String::Hash.should == Hash
-        }.should complain(/toplevel constant Hash referenced by/)
-      end
-    end
-
-    ruby_version_is "2.5" do
-      it "does not search Object after searching other scopes" do
-        -> { String::Hash }.should raise_error(NameError)
-      end
+    it "does not search Object after searching other scopes" do
+      -> { String::Hash }.should.raise(NameError)
     end
   end
 
   it "searches Object unsuccessfully when searches on a module" do
-    -> { Enumerable::Hash }.should raise_error(NameError)
+    -> { Enumerable::Hash }.should.raise(NameError)
   end
 end
 
@@ -455,39 +488,37 @@ describe "Module#private_constant marked constants" do
       mod.const_set :Foo, false
     }.should complain(/already initialized constant/)
 
-    -> {mod::Foo}.should raise_error(NameError)
+    -> {mod::Foo}.should.raise(NameError)
   end
 
-  ruby_version_is "2.6" do
-    it "sends #const_missing to the original class or module" do
-      mod = Module.new
-      mod.const_set :Foo, true
-      mod.send :private_constant, :Foo
-      def mod.const_missing(name)
-        name == :Foo ? name : super
-      end
-
-      mod::Foo.should == :Foo
+  it "sends #const_missing to the original class or module" do
+    mod = Module.new
+    mod.const_set :Foo, true
+    mod.send :private_constant, :Foo
+    def mod.const_missing(name)
+      name == :Foo ? name : super
     end
+
+    mod::Foo.should == :Foo
   end
 
   describe "in a module" do
     it "cannot be accessed from outside the module" do
       -> do
         ConstantVisibility::PrivConstModule::PRIVATE_CONSTANT_MODULE
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "cannot be reopened as a module from scope where constant would be private" do
       -> do
         module ConstantVisibility::ModuleContainer::PrivateModule; end
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "cannot be reopened as a class from scope where constant would be private" do
       -> do
         class ConstantVisibility::ModuleContainer::PrivateClass; end
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "can be reopened as a module where constant is not private" do
@@ -498,6 +529,10 @@ describe "Module#private_constant marked constants" do
 
         PrivateModule::X.should == 1
       end
+    ensure
+      module ::ConstantVisibility::ModuleContainer
+        PrivateModule.send(:remove_const, :X)
+      end
     end
 
     it "can be reopened as a class where constant is not private" do
@@ -508,6 +543,10 @@ describe "Module#private_constant marked constants" do
 
         PrivateClass::X.should == 1
       end
+    ensure
+      module ::ConstantVisibility::ModuleContainer
+        PrivateClass.send(:remove_const, :X)
+      end
     end
 
     it "is not defined? with A::B form" do
@@ -515,7 +554,7 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from the module itself" do
-      ConstantVisibility::PrivConstModule.private_constant_from_self.should be_true
+      ConstantVisibility::PrivConstModule.private_constant_from_self.should == true
     end
 
     it "is defined? from the module itself" do
@@ -523,7 +562,7 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from lexical scope" do
-      ConstantVisibility::PrivConstModule::Nested.private_constant_from_scope.should be_true
+      ConstantVisibility::PrivConstModule::Nested.private_constant_from_scope.should == true
     end
 
     it "is defined? from lexical scope" do
@@ -531,11 +570,24 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from classes that include the module" do
-      ConstantVisibility::PrivConstModuleChild.new.private_constant_from_include.should be_true
+      ConstantVisibility::ClassIncludingPrivConstModule.new.private_constant_from_include.should == true
+    end
+
+    it "can be accessed from modules that include the module" do
+      ConstantVisibility::ModuleIncludingPrivConstModule.private_constant_from_include.should == true
+    end
+
+    it "raises a NameError when accessed directly from modules that include the module" do
+      -> do
+        ConstantVisibility::ModuleIncludingPrivConstModule.private_constant_self_from_include
+      end.should.raise(NameError)
+      -> do
+        ConstantVisibility::ModuleIncludingPrivConstModule.private_constant_named_from_include
+      end.should.raise(NameError)
     end
 
     it "is defined? from classes that include the module" do
-      ConstantVisibility::PrivConstModuleChild.new.defined_from_include.should == "constant"
+      ConstantVisibility::ClassIncludingPrivConstModule.new.defined_from_include.should == "constant"
     end
   end
 
@@ -543,19 +595,19 @@ describe "Module#private_constant marked constants" do
     it "cannot be accessed from outside the class" do
       -> do
         ConstantVisibility::PrivConstClass::PRIVATE_CONSTANT_CLASS
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "cannot be reopened as a module" do
       -> do
         module ConstantVisibility::ClassContainer::PrivateModule; end
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "cannot be reopened as a class" do
       -> do
         class ConstantVisibility::ClassContainer::PrivateClass; end
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "can be reopened as a module where constant is not private" do
@@ -566,6 +618,10 @@ describe "Module#private_constant marked constants" do
 
         PrivateModule::X.should == 1
       end
+    ensure
+      class ::ConstantVisibility::ClassContainer
+        PrivateModule.send(:remove_const, :X)
+      end
     end
 
     it "can be reopened as a class where constant is not private" do
@@ -576,6 +632,10 @@ describe "Module#private_constant marked constants" do
 
         PrivateClass::X.should == 1
       end
+    ensure
+      class ::ConstantVisibility::ClassContainer
+        PrivateClass.send(:remove_const, :X)
+      end
     end
 
     it "is not defined? with A::B form" do
@@ -583,7 +643,7 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from the class itself" do
-      ConstantVisibility::PrivConstClass.private_constant_from_self.should be_true
+      ConstantVisibility::PrivConstClass.private_constant_from_self.should == true
     end
 
     it "is defined? from the class itself" do
@@ -591,7 +651,7 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from lexical scope" do
-      ConstantVisibility::PrivConstClass::Nested.private_constant_from_scope.should be_true
+      ConstantVisibility::PrivConstClass::Nested.private_constant_from_scope.should == true
     end
 
     it "is defined? from lexical scope" do
@@ -599,7 +659,7 @@ describe "Module#private_constant marked constants" do
     end
 
     it "can be accessed from subclasses" do
-      ConstantVisibility::PrivConstClassChild.new.private_constant_from_subclass.should be_true
+      ConstantVisibility::PrivConstClassChild.new.private_constant_from_subclass.should == true
     end
 
     it "is defined? from subclasses" do
@@ -611,7 +671,7 @@ describe "Module#private_constant marked constants" do
     it "cannot be accessed using ::Const form" do
       -> do
         ::PRIVATE_CONSTANT_IN_OBJECT
-      end.should raise_error(NameError)
+      end.should.raise(NameError)
     end
 
     it "is not defined? using ::Const form" do
@@ -631,14 +691,14 @@ describe "Module#private_constant marked constants" do
     it "has :receiver and :name attributes" do
       -> do
         ConstantVisibility::PrivConstClass::PRIVATE_CONSTANT_CLASS
-      end.should raise_error(NameError) {|e|
+      end.should.raise(NameError) {|e|
         e.receiver.should == ConstantVisibility::PrivConstClass
         e.name.should == :PRIVATE_CONSTANT_CLASS
       }
 
       -> do
         ConstantVisibility::PrivConstModule::PRIVATE_CONSTANT_MODULE
-      end.should raise_error(NameError) {|e|
+      end.should.raise(NameError) {|e|
         e.receiver.should == ConstantVisibility::PrivConstModule
         e.name.should == :PRIVATE_CONSTANT_MODULE
       }
@@ -647,14 +707,14 @@ describe "Module#private_constant marked constants" do
     it "has the defined class as the :name attribute" do
       -> do
         ConstantVisibility::PrivConstClassChild::PRIVATE_CONSTANT_CLASS
-      end.should raise_error(NameError) {|e|
+      end.should.raise(NameError) {|e|
         e.receiver.should == ConstantVisibility::PrivConstClass
         e.name.should == :PRIVATE_CONSTANT_CLASS
       }
 
       -> do
-        ConstantVisibility::PrivConstModuleChild::PRIVATE_CONSTANT_MODULE
-      end.should raise_error(NameError) {|e|
+        ConstantVisibility::ClassIncludingPrivConstModule::PRIVATE_CONSTANT_MODULE
+      end.should.raise(NameError) {|e|
         e.receiver.should == ConstantVisibility::PrivConstModule
         e.name.should == :PRIVATE_CONSTANT_MODULE
       }
@@ -723,23 +783,27 @@ describe 'Allowed characters' do
   it 'does not allow not ASCII characters that cannot be upcased or lowercased at the beginning' do
     -> do
       Module.new.const_set("થBB", 1)
-    end.should raise_error(NameError, /wrong constant name/)
+    end.should.raise(NameError, /wrong constant name/)
   end
 
-  ruby_version_is ""..."2.6" do
-    it 'does not allow not ASCII upcased characters at the beginning' do
-      -> do
-        Module.new.const_set("ἍBB", 1)
-      end.should raise_error(NameError, /wrong constant name/)
-    end
-  end
+  it 'allows not ASCII upcased characters at the beginning' do
+    mod = Module.new
+    mod.const_set("ἍBB", 1)
 
-  ruby_version_is "2.6" do
-    it 'allows not ASCII upcased characters at the beginning' do
-      mod = Module.new
-      mod.const_set("ἍBB", 1)
+    eval("mod::ἍBB").should == 1
+  end
+end
 
-      eval("mod::ἍBB").should == 1
+describe 'Assignment' do
+  context 'dynamic assignment' do
+    it 'raises SyntaxError' do
+      -> do
+        eval <<-CODE
+          def test
+            B = 1
+          end
+        CODE
+      end.should.raise(SyntaxError, /dynamic constant assignment/)
     end
   end
 end
diff --git a/spec/ruby/language/def_spec.rb b/spec/ruby/language/def_spec.rb
index 82813bd36c..82c89a0d08 100644
--- a/spec/ruby/language/def_spec.rb
+++ b/spec/ruby/language/def_spec.rb
@@ -14,11 +14,11 @@ end
 
 describe "Defining a method at the top-level" do
   it "defines it on Object with private visibility by default" do
-    Object.should have_private_instance_method(:some_toplevel_method, false)
+    Object.private_instance_methods(false).should.include?(:some_toplevel_method)
   end
 
   it "defines it on Object with public visibility after calling public" do
-    Object.should have_public_instance_method(:public_toplevel_method, false)
+    Object.public_instance_methods(false).should.include?(:public_toplevel_method)
   end
 end
 
@@ -28,7 +28,7 @@ describe "Defining an 'initialize' method" do
       def initialize
       end
     end
-    DefInitializeSpec.should have_private_instance_method(:initialize, false)
+    DefInitializeSpec.private_instance_methods(false).should.include?(:initialize)
   end
 end
 
@@ -38,7 +38,7 @@ describe "Defining an 'initialize_copy' method" do
       def initialize_copy
       end
     end
-    DefInitializeCopySpec.should have_private_instance_method(:initialize_copy, false)
+    DefInitializeCopySpec.private_instance_methods(false).should.include?(:initialize_copy)
   end
 end
 
@@ -48,7 +48,7 @@ describe "Defining an 'initialize_dup' method" do
       def initialize_dup
       end
     end
-    DefInitializeDupSpec.should have_private_instance_method(:initialize_dup, false)
+    DefInitializeDupSpec.private_instance_methods(false).should.include?(:initialize_dup)
   end
 end
 
@@ -58,7 +58,7 @@ describe "Defining an 'initialize_clone' method" do
       def initialize_clone
       end
     end
-    DefInitializeCloneSpec.should have_private_instance_method(:initialize_clone, false)
+    DefInitializeCloneSpec.private_instance_methods(false).should.include?(:initialize_clone)
   end
 end
 
@@ -68,7 +68,7 @@ describe "Defining a 'respond_to_missing?' method" do
       def respond_to_missing?
       end
     end
-    DefRespondToMissingPSpec.should have_private_instance_method(:respond_to_missing?, false)
+    DefRespondToMissingPSpec.private_instance_methods(false).should.include?(:respond_to_missing?)
   end
 end
 
@@ -82,12 +82,34 @@ end
 describe "An instance method" do
   it "raises an error with too few arguments" do
     def foo(a, b); end
-    -> { foo 1 }.should raise_error(ArgumentError, 'wrong number of arguments (given 1, expected 2)')
+    -> { foo 1 }.should.raise(ArgumentError, 'wrong number of arguments (given 1, expected 2)')
   end
 
   it "raises an error with too many arguments" do
     def foo(a); end
-    -> { foo 1, 2 }.should raise_error(ArgumentError, 'wrong number of arguments (given 2, expected 1)')
+    -> { foo 1, 2 }.should.raise(ArgumentError, 'wrong number of arguments (given 2, expected 1)')
+  end
+
+  it "raises FrozenError with the correct class name" do
+    -> {
+      Module.new do
+        self.freeze
+        def foo; end
+      end
+    }.should.raise(FrozenError) { |e|
+      msg_class = ruby_version_is("4.0") ? "Module" : "module"
+      e.message.should == "can't modify frozen #{msg_class}: #{e.receiver}"
+    }
+
+    -> {
+      Class.new do
+        self.freeze
+        def foo; end
+      end
+    }.should.raise(FrozenError){ |e|
+      msg_class = ruby_version_is("4.0") ? "Class" : "class"
+      e.message.should == "can't modify frozen #{msg_class}: #{e.receiver}"
+    }
   end
 end
 
@@ -113,12 +135,12 @@ describe "An instance method definition with a splat" do
   end
 
   it "allows only a single * argument" do
-    -> { eval 'def foo(a, *b, *c); end' }.should raise_error(SyntaxError)
+    -> { eval 'def foo(a, *b, *c); end' }.should.raise(SyntaxError)
   end
 
   it "requires the presence of any arguments that precede the *" do
     def foo(a, b, *c); end
-    -> { foo 1 }.should raise_error(ArgumentError, 'wrong number of arguments (given 1, expected 2+)')
+    -> { foo 1 }.should.raise(ArgumentError, 'wrong number of arguments (given 1, expected 2+)')
   end
 end
 
@@ -151,7 +173,7 @@ describe "An instance method with a default argument" do
     def foo(a, b = 2)
       [a,b]
     end
-    -> { foo }.should raise_error(ArgumentError, 'wrong number of arguments (given 0, expected 1..2)')
+    -> { foo }.should.raise(ArgumentError, 'wrong number of arguments (given 0, expected 1..2)')
     foo(1).should == [1, 2]
   end
 
@@ -159,7 +181,7 @@ describe "An instance method with a default argument" do
     def foo(a, b = 2, *c)
       [a,b,c]
     end
-    -> { foo }.should raise_error(ArgumentError, 'wrong number of arguments (given 0, expected 1+)')
+    -> { foo }.should.raise(ArgumentError, 'wrong number of arguments (given 0, expected 1+)')
     foo(1).should == [1,2,[]]
   end
 
@@ -177,17 +199,25 @@ describe "An instance method with a default argument" do
     foo(2,3,3).should == [2,3,[3]]
   end
 
-  it "shadows an existing method with the same name as the local" do
-    def bar
-      1
+  ruby_version_is ""..."3.4" do
+    it "raises a SyntaxError if using the argument in its default value" do
+      -> {
+        eval "def foo(bar = bar)
+          bar
+        end"
+      }.should.raise(SyntaxError)
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "is nil if using the argument in its default value" do
+      -> {
+        eval "def foo(bar = bar)
+          bar
+        end
+        foo"
+      }.call.should == nil
     end
-    -> {
-      eval "def foo(bar = bar)
-        bar
-      end"
-    }.should complain(/circular argument reference/)
-    foo.should == nil
-    foo(2).should == 2
   end
 
   it "calls a method with the same name as the local when explicitly using ()" do
@@ -220,7 +250,7 @@ describe "A singleton method definition" do
   end
 
   it "can be declared for a global variable" do
-    $__a__ = "hi"
+    $__a__ = +"hi"
     def $__a__.foo
       7
     end
@@ -246,10 +276,30 @@ describe "A singleton method definition" do
     (obj==2).should == 2
   end
 
-  it "raises #{frozen_error_class} if frozen" do
+  it "raises FrozenError if frozen" do
+    obj = Object.new
+    obj.freeze
+    -> { def obj.foo; end }.should.raise(FrozenError)
+  end
+
+  it "raises FrozenError with the correct class name" do
     obj = Object.new
     obj.freeze
-    -> { def obj.foo; end }.should raise_error(frozen_error_class)
+    msg_class = ruby_version_is("4.0") ? "Object" : "object"
+    -> { def obj.foo; end }.should.raise(FrozenError, "can't modify frozen #{msg_class}: #{obj}")
+
+    obj = Object.new
+    c = obj.singleton_class
+    c.singleton_class.freeze
+    -> { def c.foo; end }.should.raise(FrozenError, "can't modify frozen Class: #{c}")
+
+    c = Class.new
+    c.freeze
+    -> { def c.foo; end }.should.raise(FrozenError, "can't modify frozen Class: #{c}")
+
+    m = Module.new
+    m.freeze
+    -> { def m.foo; end }.should.raise(FrozenError, "can't modify frozen Module: #{m}")
   end
 end
 
@@ -384,7 +434,7 @@ describe "A method definition inside a metaclass scope" do
     end
 
     DefSpecSingleton.a_class_method.should == DefSpecSingleton
-    -> { Object.a_class_method }.should raise_error(NoMethodError)
+    -> { Object.a_class_method }.should.raise(NoMethodError)
   end
 
   it "can create a singleton method" do
@@ -394,15 +444,15 @@ describe "A method definition inside a metaclass scope" do
     end
 
     obj.a_singleton_method.should == obj
-    -> { Object.new.a_singleton_method }.should raise_error(NoMethodError)
+    -> { Object.new.a_singleton_method }.should.raise(NoMethodError)
   end
 
-  it "raises #{frozen_error_class} if frozen" do
+  it "raises FrozenError if frozen" do
     obj = Object.new
     obj.freeze
 
     class << obj
-      -> { def foo; end }.should raise_error(frozen_error_class)
+      -> { def foo; end }.should.raise(FrozenError)
     end
   end
 end
@@ -423,7 +473,7 @@ describe "A nested method definition" do
     other = DefSpecNested.new
     other.an_instance_method.should == other
 
-    DefSpecNested.should have_instance_method(:an_instance_method)
+    DefSpecNested.should.method_defined?(:an_instance_method, false)
   end
 
   it "creates a class method when evaluated in a class method" do
@@ -438,11 +488,11 @@ describe "A nested method definition" do
       end
     end
 
-    -> { DefSpecNested.a_class_method }.should raise_error(NoMethodError)
+    -> { DefSpecNested.a_class_method }.should.raise(NoMethodError)
     DefSpecNested.create_class_method.should == DefSpecNested
     DefSpecNested.a_class_method.should == DefSpecNested
-    -> { Object.a_class_method }.should raise_error(NoMethodError)
-    -> { DefSpecNested.new.a_class_method }.should raise_error(NoMethodError)
+    -> { Object.a_class_method }.should.raise(NoMethodError)
+    -> { DefSpecNested.new.a_class_method }.should.raise(NoMethodError)
   end
 
   it "creates a singleton method when evaluated in the metaclass of an instance" do
@@ -460,7 +510,7 @@ describe "A nested method definition" do
     obj.a_singleton_method.should == obj
 
     other = DefSpecNested.new
-    -> { other.a_singleton_method }.should raise_error(NoMethodError)
+    -> { other.a_singleton_method }.should.raise(NoMethodError)
   end
 
   it "creates a method in the surrounding context when evaluated in a def expr.method" do
@@ -472,11 +522,13 @@ describe "A nested method definition" do
     end
 
     DefSpecNested::TARGET.defs_method
-    DefSpecNested.should have_instance_method :inherited_method
-    DefSpecNested::TARGET.should_not have_method :inherited_method
+    DefSpecNested.should.method_defined?(:inherited_method, false)
+    DefSpecNested::TARGET.should_not.respond_to? :inherited_method
 
     obj = DefSpecNested.new
     obj.inherited_method.should == obj
+  ensure
+    DefSpecNested.send(:remove_const, :TARGET)
   end
 
   # See http://yugui.jp/articles/846#label-3
@@ -493,11 +545,13 @@ describe "A nested method definition" do
     obj = DefSpecNested::OBJ
     obj.create_method_in_instance_eval
 
-    obj.should have_method :arg_method
-    obj.should have_method :body_method
+    obj.should.respond_to? :arg_method
+    obj.should.respond_to? :body_method
 
-    DefSpecNested.should_not have_instance_method :arg_method
-    DefSpecNested.should_not have_instance_method :body_method
+    DefSpecNested.should_not.method_defined? :arg_method
+    DefSpecNested.should_not.method_defined? :body_method
+  ensure
+    DefSpecNested.send(:remove_const, :OBJ)
   end
 
   it "creates an instance method inside Class.new" do
@@ -515,7 +569,7 @@ describe "A nested method definition" do
 
     cls.new.new_def.should == 1
 
-    -> { Object.new.new_def }.should raise_error(NoMethodError)
+    -> { Object.new.new_def }.should.raise(NoMethodError)
   end
 end
 
@@ -531,18 +585,18 @@ describe "A method definition always resets the visibility to public for nested
     end
 
     obj = cls.new
-    -> { obj.do_def }.should raise_error(NoMethodError, /private/)
+    -> { obj.do_def }.should.raise(NoMethodError, /private/)
     obj.send :do_def
     obj.new_def.should == 1
 
     cls.new.new_def.should == 1
 
-    -> { Object.new.new_def }.should raise_error(NoMethodError)
+    -> { Object.new.new_def }.should.raise(NoMethodError)
   end
 
   it "at the toplevel" do
     obj = Object.new
-    -> { obj.toplevel_define_other_method }.should raise_error(NoMethodError, /private/)
+    -> { obj.toplevel_define_other_method }.should.raise(NoMethodError, /private/)
     toplevel_define_other_method
     nested_method_in_toplevel_method.should == 42
 
@@ -559,7 +613,7 @@ describe "A method definition inside an instance_eval" do
     obj.an_instance_eval_method.should == obj
 
     other = Object.new
-    -> { other.an_instance_eval_method }.should raise_error(NoMethodError)
+    -> { other.an_instance_eval_method }.should.raise(NoMethodError)
   end
 
   it "creates a singleton method when evaluated inside a metaclass" do
@@ -572,7 +626,7 @@ describe "A method definition inside an instance_eval" do
     obj.a_metaclass_eval_method.should == obj
 
     other = Object.new
-    -> { other.a_metaclass_eval_method }.should raise_error(NoMethodError)
+    -> { other.a_metaclass_eval_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method when the receiver is a class" do
@@ -581,7 +635,7 @@ describe "A method definition inside an instance_eval" do
     end
 
     DefSpecNested.an_instance_eval_class_method.should == DefSpecNested
-    -> { Object.an_instance_eval_class_method }.should raise_error(NoMethodError)
+    -> { Object.an_instance_eval_class_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method when the receiver is an anonymous class" do
@@ -593,7 +647,7 @@ describe "A method definition inside an instance_eval" do
     end
 
     m.klass_method.should == :test
-    -> { Object.klass_method }.should raise_error(NoMethodError)
+    -> { Object.klass_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method when instance_eval is within class" do
@@ -606,7 +660,7 @@ describe "A method definition inside an instance_eval" do
     end
 
     m.klass_method.should == :test
-    -> { Object.klass_method }.should raise_error(NoMethodError)
+    -> { Object.klass_method }.should.raise(NoMethodError)
   end
 end
 
@@ -619,7 +673,7 @@ describe "A method definition inside an instance_exec" do
     end
 
     DefSpecNested.an_instance_exec_class_method.should == 1
-    -> { Object.an_instance_exec_class_method }.should raise_error(NoMethodError)
+    -> { Object.an_instance_exec_class_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method when the receiver is an anonymous class" do
@@ -633,7 +687,7 @@ describe "A method definition inside an instance_exec" do
     end
 
     m.klass_method.should == 1
-    -> { Object.klass_method }.should raise_error(NoMethodError)
+    -> { Object.klass_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method when instance_exec is within class" do
@@ -648,7 +702,7 @@ describe "A method definition inside an instance_exec" do
     end
 
     m.klass_method.should == 2
-    -> { Object.klass_method }.should raise_error(NoMethodError)
+    -> { Object.klass_method }.should.raise(NoMethodError)
   end
 end
 
@@ -668,7 +722,7 @@ describe "A method definition in an eval" do
     other = DefSpecNested.new
     other.an_eval_instance_method.should == other
 
-    -> { Object.new.an_eval_instance_method }.should raise_error(NoMethodError)
+    -> { Object.new.an_eval_instance_method }.should.raise(NoMethodError)
   end
 
   it "creates a class method" do
@@ -684,8 +738,8 @@ describe "A method definition in an eval" do
     DefSpecNestedB.eval_class_method.should == DefSpecNestedB
     DefSpecNestedB.an_eval_class_method.should == DefSpecNestedB
 
-    -> { Object.an_eval_class_method }.should raise_error(NoMethodError)
-    -> { DefSpecNestedB.new.an_eval_class_method}.should raise_error(NoMethodError)
+    -> { Object.an_eval_class_method }.should.raise(NoMethodError)
+    -> { DefSpecNestedB.new.an_eval_class_method}.should.raise(NoMethodError)
   end
 
   it "creates a singleton method" do
@@ -703,7 +757,7 @@ describe "A method definition in an eval" do
     obj.an_eval_singleton_method.should == obj
 
     other = DefSpecNested.new
-    -> { other.an_eval_singleton_method }.should raise_error(NoMethodError)
+    -> { other.an_eval_singleton_method }.should.raise(NoMethodError)
   end
 end
 
@@ -714,8 +768,8 @@ describe "a method definition that sets more than one default parameter all to t
   it "assigns them all the same object by default" do
     foo.should == [{},{},{}]
     a, b, c = foo
-    a.should eql(b)
-    a.should eql(c)
+    a.should.eql?(b)
+    a.should.eql?(c)
   end
 
   it "allows the first argument to be given, and sets the rest to null" do
@@ -725,11 +779,11 @@ describe "a method definition that sets more than one default parameter all to t
   it "assigns the parameters different objects across different default calls" do
     a, _b, _c = foo
     d, _e, _f = foo
-    a.should_not equal(d)
+    a.should_not.equal?(d)
   end
 
   it "only allows overriding the default value of the first such parameter in each set" do
-    -> { foo(1,2) }.should raise_error(ArgumentError, 'wrong number of arguments (given 2, expected 0..1)')
+    -> { foo(1,2) }.should.raise(ArgumentError, 'wrong number of arguments (given 2, expected 0..1)')
   end
 
   def bar(a=b=c=1,d=2)
@@ -740,7 +794,7 @@ describe "a method definition that sets more than one default parameter all to t
     bar.should == [1,1,1,2]
     bar(3).should == [3,nil,nil,2]
     bar(3,4).should == [3,nil,nil,4]
-    -> { bar(3,4,5) }.should raise_error(ArgumentError, 'wrong number of arguments (given 3, expected 0..2)')
+    -> { bar(3,4,5) }.should.raise(ArgumentError, 'wrong number of arguments (given 3, expected 0..2)')
   end
 end
 
@@ -755,7 +809,7 @@ describe "The def keyword" do
         }.call
       end
 
-      DefSpecsLambdaVisibility.should have_private_instance_method("some_method")
+      DefSpecsLambdaVisibility.private_instance_methods(false).should.include?(:some_method)
     end
   end
 end
diff --git a/spec/ruby/language/defined_spec.rb b/spec/ruby/language/defined_spec.rb
index 02c69d27b8..6846179a7c 100644
--- a/spec/ruby/language/defined_spec.rb
+++ b/spec/ruby/language/defined_spec.rb
@@ -5,21 +5,25 @@ describe "The defined? keyword for literals" do
   it "returns 'self' for self" do
     ret = defined?(self)
     ret.should == "self"
+    ret.frozen?.should == true
   end
 
   it "returns 'nil' for nil" do
     ret = defined?(nil)
     ret.should == "nil"
+    ret.frozen?.should == true
   end
 
   it "returns 'true' for true" do
     ret = defined?(true)
     ret.should == "true"
+    ret.frozen?.should == true
   end
 
   it "returns 'false' for false" do
     ret = defined?(false)
     ret.should == "false"
+    ret.frozen?.should == true
   end
 
   describe "for a literal Array" do
@@ -27,6 +31,7 @@ describe "The defined? keyword for literals" do
     it "returns 'expression' if each element is defined" do
       ret = defined?([Object, Array])
       ret.should == "expression"
+      ret.frozen?.should == true
     end
 
     it "returns nil if one element is not defined" do
@@ -43,13 +48,29 @@ describe "The defined? keyword for literals" do
 end
 
 describe "The defined? keyword when called with a method name" do
+  before :each do
+    ScratchPad.clear
+  end
+
+  it "does not call the method" do
+    defined?(DefinedSpecs.side_effects).should == "method"
+    ScratchPad.recorded.should != :defined_specs_side_effects
+  end
+
+  it "does not execute the arguments" do
+    defined?(DefinedSpecs.any_args(DefinedSpecs.side_effects)).should == "method"
+    ScratchPad.recorded.should != :defined_specs_side_effects
+  end
+
   describe "without a receiver" do
     it "returns 'method' if the method is defined" do
-      defined?(puts).should == "method"
+      ret = defined?(puts)
+      ret.should == "method"
+      ret.frozen?.should == true
     end
 
     it "returns nil if the method is not defined" do
-      defined?(defined_specs_undefined_method).should be_nil
+      defined?(defined_specs_undefined_method).should == nil
     end
 
     it "returns 'method' if the method is defined and private" do
@@ -69,23 +90,23 @@ describe "The defined? keyword when called with a method name" do
     end
 
     it "returns nil if the method is private" do
-      defined?(Object.print).should be_nil
+      defined?(Object.print).should == nil
     end
 
     it "returns nil if the method is protected" do
-      defined?(DefinedSpecs::Basic.new.protected_method).should be_nil
+      defined?(DefinedSpecs::Basic.new.protected_method).should == nil
     end
 
     it "returns nil if the method is not defined" do
-      defined?(Kernel.defined_specs_undefined_method).should be_nil
+      defined?(Kernel.defined_specs_undefined_method).should == nil
     end
 
     it "returns nil if the class is not defined" do
-      defined?(DefinedSpecsUndefined.puts).should be_nil
+      defined?(DefinedSpecsUndefined.puts).should == nil
     end
 
     it "returns nil if the subclass is not defined" do
-      defined?(DefinedSpecs::Undefined.puts).should be_nil
+      defined?(DefinedSpecs::Undefined.puts).should == nil
     end
   end
 
@@ -95,13 +116,18 @@ describe "The defined? keyword when called with a method name" do
       defined?(obj.a_defined_method).should == "method"
     end
 
+    it "returns 'method' for []=" do
+      a = []
+      defined?(a[0] = 1).should == "method"
+    end
+
     it "returns nil if the method is not defined" do
       obj = DefinedSpecs::Basic.new
-      defined?(obj.an_undefined_method).should be_nil
+      defined?(obj.an_undefined_method).should == nil
     end
 
     it "returns nil if the variable does not exist" do
-      defined?(nonexistent_local_variable.some_method).should be_nil
+      defined?(nonexistent_local_variable.some_method).should == nil
     end
 
     it "calls #respond_to_missing?" do
@@ -119,11 +145,11 @@ describe "The defined? keyword when called with a method name" do
 
     it "returns nil if the method is not defined" do
       @defined_specs_obj = DefinedSpecs::Basic.new
-      defined?(@defined_specs_obj.an_undefined_method).should be_nil
+      defined?(@defined_specs_obj.an_undefined_method).should == nil
     end
 
     it "returns nil if the variable does not exist" do
-      defined?(@nonexistent_instance_variable.some_method).should be_nil
+      defined?(@nonexistent_instance_variable.some_method).should == nil
     end
   end
 
@@ -135,22 +161,22 @@ describe "The defined? keyword when called with a method name" do
 
     it "returns nil if the method is not defined" do
       $defined_specs_obj = DefinedSpecs::Basic.new
-      defined?($defined_specs_obj.an_undefined_method).should be_nil
+      defined?($defined_specs_obj.an_undefined_method).should == nil
     end
 
     it "returns nil if the variable does not exist" do
-      defined?($nonexistent_global_variable.some_method).should be_nil
+      defined?($nonexistent_global_variable.some_method).should == nil
     end
   end
 
   describe "having a method call as a receiver" do
     it "returns nil if evaluating the receiver raises an exception" do
-      defined?(DefinedSpecs.exception_method / 2).should be_nil
+      defined?(DefinedSpecs.exception_method / 2).should == nil
       ScratchPad.recorded.should == :defined_specs_exception
     end
 
     it "returns nil if the method is not defined on the object the receiver returns" do
-      defined?(DefinedSpecs.side_effects / 2).should be_nil
+      defined?(DefinedSpecs.side_effects / 2).should == nil
       ScratchPad.recorded.should == :defined_specs_side_effects
     end
 
@@ -159,6 +185,48 @@ describe "The defined? keyword when called with a method name" do
       ScratchPad.recorded.should == :defined_specs_fixnum_method
     end
   end
+
+  describe "having a throw in the receiver" do
+    it "escapes defined? and performs the throw semantics as normal" do
+      defined_returned = false
+      catch(:out) {
+        # NOTE: defined? behaves differently if it is called in a void context, see below
+        defined?(throw(:out, 42).foo).should == :unreachable
+        defined_returned = true
+      }.should == 42
+      defined_returned.should == false
+    end
+  end
+
+  describe "in a void context" do
+    it "does not execute the receiver" do
+      ScratchPad.record :not_executed
+      defined?(DefinedSpecs.side_effects / 2)
+      ScratchPad.recorded.should == :not_executed
+    end
+
+    it "warns about the void context when parsing it" do
+      -> {
+        eval "defined?(DefinedSpecs.side_effects / 2); 42"
+      }.should complain(/warning: possibly useless use of defined\? in void context/, verbose: true)
+    end
+  end
+
+  describe "for a protected method" do
+    it "returns 'method' when the receiver is a subclass instance" do
+      DefinedSpecs::ProtectedBase.new.defined_on(DefinedSpecs::ProtectedSubclass.new).should == "method"
+    end
+
+    it "returns 'method' when the receiver is the base class instance" do
+      DefinedSpecs::ProtectedSubclass.new.defined_on(DefinedSpecs::ProtectedBase.new).should == "method"
+    end
+
+    ruby_bug "#22076", ""..."4.1" do
+      it "returns 'method' when the receiver is a sibling class instance via a shared included module" do
+        DefinedSpecs::ProtectedIncluderA.new.defined_on(DefinedSpecs::ProtectedIncluderB.new).should == "method"
+      end
+    end
+  end
 end
 
 describe "The defined? keyword for an expression" do
@@ -167,7 +235,9 @@ describe "The defined? keyword for an expression" do
   end
 
   it "returns 'assignment' for assigning a local variable" do
-    defined?(x = 2).should == "assignment"
+    ret = defined?(x = 2)
+    ret.should == "assignment"
+    ret.frozen?.should == true
   end
 
   it "returns 'assignment' for assigning an instance variable" do
@@ -182,6 +252,14 @@ describe "The defined? keyword for an expression" do
     defined?(@@defined_specs_x = 2).should == "assignment"
   end
 
+  it "returns 'assignment' for assigning a constant" do
+    defined?(A = 2).should == "assignment"
+  end
+
+  it "returns 'assignment' for assigning a fully qualified constant" do
+    defined?(Object::A = 2).should == "assignment"
+  end
+
   it "returns 'assignment' for assigning multiple variables" do
     defined?((a, b = 1, 2)).should == "assignment"
   end
@@ -199,7 +277,27 @@ describe "The defined? keyword for an expression" do
   end
 
   it "returns 'assignment' for an expression with '+='" do
-    defined?(x += 2).should == "assignment"
+    defined?(a += 1).should == "assignment"
+    defined?(@a += 1).should == "assignment"
+    defined?(@@a += 1).should == "assignment"
+    defined?($a += 1).should == "assignment"
+    defined?(A += 1).should == "assignment"
+    # fully qualified constant check is moved out into a separate test case
+    defined?(a.b += 1).should == "assignment"
+    defined?(a[:b] += 1).should == "assignment"
+  end
+
+  # https://bugs.ruby-lang.org/issues/20111
+  ruby_version_is ""..."3.4" do
+    it "returns 'expression' for an assigning a fully qualified constant with '+='" do
+      defined?(Object::A += 1).should == "expression"
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "returns 'assignment' for an assigning a fully qualified constant with '+='" do
+      defined?(Object::A += 1).should == "assignment"
+    end
   end
 
   it "returns 'assignment' for an expression with '*='" do
@@ -230,12 +328,90 @@ describe "The defined? keyword for an expression" do
     defined?(x >>= 2).should == "assignment"
   end
 
-  it "returns 'assignment' for an expression with '||='" do
-    defined?(x ||= 2).should == "assignment"
+  context "||=" do
+    it "returns 'assignment' for assigning a local variable with '||='" do
+      defined?(a ||= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning an instance variable with '||='" do
+      defined?(@a ||= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a class variable with '||='" do
+      defined?(@@a ||= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a global variable with '||='" do
+      defined?($a ||= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a constant with '||='" do
+      defined?(A ||= true).should == "assignment"
+    end
+
+    # https://bugs.ruby-lang.org/issues/20111
+    ruby_version_is ""..."3.4" do
+      it "returns 'expression' for assigning a fully qualified constant with '||='" do
+        defined?(Object::A ||= true).should == "expression"
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "returns 'assignment' for assigning a fully qualified constant with '||='" do
+        defined?(Object::A ||= true).should == "assignment"
+      end
+    end
+
+    it "returns 'assignment' for assigning an attribute with '||='" do
+      defined?(a.b ||= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a referenced element with '||='" do
+      defined?(a[:b] ||= true).should == "assignment"
+    end
   end
 
-  it "returns 'assignment' for an expression with '&&='" do
-    defined?(x &&= 2).should == "assignment"
+  context "&&=" do
+    it "returns 'assignment' for assigning a local variable with '&&='" do
+      defined?(a &&= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning an instance variable with '&&='" do
+      defined?(@a &&= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a class variable with '&&='" do
+      defined?(@@a &&= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a global variable with '&&='" do
+      defined?($a &&= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a constant with '&&='" do
+      defined?(A &&= true).should == "assignment"
+    end
+
+    # https://bugs.ruby-lang.org/issues/20111
+    ruby_version_is ""..."3.4" do
+      it "returns 'expression' for assigning a fully qualified constant with '&&='" do
+        defined?(Object::A &&= true).should == "expression"
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "returns 'assignment' for assigning a fully qualified constant with '&&='" do
+        defined?(Object::A &&= true).should == "assignment"
+      end
+    end
+
+    it "returns 'assignment' for assigning an attribute with '&&='" do
+      defined?(a.b &&= true).should == "assignment"
+    end
+
+    it "returns 'assignment' for assigning a referenced element with '&&='" do
+      defined?(a[:b] &&= true).should == "assignment"
+    end
   end
 
   it "returns 'assignment' for an expression with '**='" do
@@ -243,15 +419,15 @@ describe "The defined? keyword for an expression" do
   end
 
   it "returns nil for an expression with == and an undefined method" do
-    defined?(defined_specs_undefined_method == 2).should be_nil
+    defined?(defined_specs_undefined_method == 2).should == nil
   end
 
   it "returns nil for an expression with != and an undefined method" do
-    defined?(defined_specs_undefined_method != 2).should be_nil
+    defined?(defined_specs_undefined_method != 2).should == nil
   end
 
   it "returns nil for an expression with !~ and an undefined method" do
-    defined?(defined_specs_undefined_method !~ 2).should be_nil
+    defined?(defined_specs_undefined_method !~ 2).should == nil
   end
 
   it "returns 'method' for an expression with '=='" do
@@ -271,29 +447,25 @@ describe "The defined? keyword for an expression" do
 
   describe "with logical connectives" do
     it "returns nil for an expression with '!' and an undefined method" do
-      defined?(!defined_specs_undefined_method).should be_nil
+      defined?(!defined_specs_undefined_method).should == nil
     end
 
     it "returns nil for an expression with '!' and an unset class variable" do
-      -> {
-        @result = defined?(!@@defined_specs_undefined_class_variable)
-      }.should complain(/class variable access from toplevel/)
-      @result.should be_nil
+      @result = eval("class singleton_class::A; defined?(!@@doesnt_exist) end", binding, __FILE__, __LINE__)
+      @result.should == nil
     end
 
     it "returns nil for an expression with 'not' and an undefined method" do
-      defined?(not defined_specs_undefined_method).should be_nil
+      defined?(not defined_specs_undefined_method).should == nil
     end
 
     it "returns nil for an expression with 'not' and an unset class variable" do
-      -> {
-        @result = defined?(not @@defined_specs_undefined_class_variable)
-      }.should complain(/class variable access from toplevel/)
-      @result.should be_nil
+      @result = eval("class singleton_class::A; defined?(not @@doesnt_exist) end", binding, __FILE__, __LINE__)
+      @result.should == nil
     end
 
     it "does not propagate an exception raised by a method in a 'not' expression" do
-      defined?(not DefinedSpecs.exception_method).should be_nil
+      defined?(not DefinedSpecs.exception_method).should == nil
       ScratchPad.recorded.should == :defined_specs_exception
     end
 
@@ -332,11 +504,11 @@ describe "The defined? keyword for an expression" do
     end
 
     it "returns nil for an expression with '!' and an unset global variable" do
-      defined?(!$defined_specs_undefined_global_variable).should be_nil
+      defined?(!$defined_specs_undefined_global_variable).should == nil
     end
 
     it "returns nil for an expression with '!' and an unset instance variable" do
-      defined?(!@defined_specs_undefined_instance_variable).should be_nil
+      defined?(!@defined_specs_undefined_instance_variable).should == nil
     end
 
     it "returns 'method' for a 'not' expression with a method" do
@@ -349,11 +521,11 @@ describe "The defined? keyword for an expression" do
     end
 
     it "returns nil for an expression with 'not' and an unset global variable" do
-      defined?(not $defined_specs_undefined_global_variable).should be_nil
+      defined?(not $defined_specs_undefined_global_variable).should == nil
     end
 
     it "returns nil for an expression with 'not' and an unset instance variable" do
-      defined?(not @defined_specs_undefined_instance_variable).should be_nil
+      defined?(not @defined_specs_undefined_instance_variable).should == nil
     end
 
     it "returns 'expression' for an expression with '&&/and' and an undefined method" do
@@ -368,12 +540,12 @@ describe "The defined? keyword for an expression" do
 
     it "does not call a method in an '&&' expression and returns 'expression'" do
       defined?(DefinedSpecs.side_effects && true).should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
 
     it "does not call a method in an 'and' expression and returns 'expression'" do
       defined?(DefinedSpecs.side_effects and true).should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
 
     it "returns 'expression' for an expression with '||/or' and an undefined method" do
@@ -388,12 +560,12 @@ describe "The defined? keyword for an expression" do
 
     it "does not call a method in an '||' expression and returns 'expression'" do
       defined?(DefinedSpecs.side_effects || true).should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
 
     it "does not call a method in an 'or' expression and returns 'expression'" do
       defined?(DefinedSpecs.side_effects or true).should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
   end
 
@@ -416,7 +588,7 @@ describe "The defined? keyword for an expression" do
 
     it "does not call the method in the String" do
       defined?("garble #{DefinedSpecs.dynamic_string}").should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
   end
 
@@ -435,7 +607,7 @@ describe "The defined? keyword for an expression" do
 
     it "does not call the method in the Regexp" do
       defined?(/garble #{DefinedSpecs.dynamic_string}/).should == "expression"
-      ScratchPad.recorded.should be_nil
+      ScratchPad.recorded.should == nil
     end
   end
 
@@ -474,7 +646,9 @@ end
 
 describe "The defined? keyword for variables" do
   it "returns 'local-variable' when called with the name of a local variable" do
-    DefinedSpecs::Basic.new.local_variable_defined.should == "local-variable"
+    ret = DefinedSpecs::Basic.new.local_variable_defined
+    ret.should == "local-variable"
+    ret.frozen?.should == true
   end
 
   it "returns 'local-variable' when called with the name of a local variable assigned to nil" do
@@ -482,15 +656,17 @@ describe "The defined? keyword for variables" do
   end
 
   it "returns nil for an instance variable that has not been read" do
-    DefinedSpecs::Basic.new.instance_variable_undefined.should be_nil
+    DefinedSpecs::Basic.new.instance_variable_undefined.should == nil
   end
 
   it "returns nil for an instance variable that has been read but not assigned to" do
-    DefinedSpecs::Basic.new.instance_variable_read.should be_nil
+    DefinedSpecs::Basic.new.instance_variable_read.should == nil
   end
 
   it "returns 'instance-variable' for an instance variable that has been assigned" do
-    DefinedSpecs::Basic.new.instance_variable_defined.should == "instance-variable"
+    ret = DefinedSpecs::Basic.new.instance_variable_defined
+    ret.should == "instance-variable"
+    ret.frozen?.should == true
   end
 
   it "returns 'instance-variable' for an instance variable that has been assigned to nil" do
@@ -498,15 +674,17 @@ describe "The defined? keyword for variables" do
   end
 
   it "returns nil for a global variable that has not been read" do
-    DefinedSpecs::Basic.new.global_variable_undefined.should be_nil
+    DefinedSpecs::Basic.new.global_variable_undefined.should == nil
   end
 
   it "returns nil for a global variable that has been read but not assigned to" do
-    DefinedSpecs::Basic.new.global_variable_read.should be_nil
+    DefinedSpecs::Basic.new.global_variable_read.should == nil
   end
 
   it "returns 'global-variable' for a global variable that has been assigned nil" do
-    DefinedSpecs::Basic.new.global_variable_defined_as_nil.should == "global-variable"
+    ret = DefinedSpecs::Basic.new.global_variable_defined_as_nil
+    ret.should == "global-variable"
+    ret.frozen?.should == true
   end
 
   # MRI appears to special case defined? for $! and $~ in that it returns
@@ -532,27 +710,27 @@ describe "The defined? keyword for variables" do
     end
 
     it "returns nil for $&" do
-      defined?($&).should be_nil
+      defined?($&).should == nil
     end
 
     it "returns nil for $`" do
-      defined?($`).should be_nil
+      defined?($`).should == nil
     end
 
     it "returns nil for $'" do
-      defined?($').should be_nil
+      defined?($').should == nil
     end
 
     it "returns nil for $+" do
-      defined?($+).should be_nil
+      defined?($+).should == nil
     end
 
     it "returns nil for any last match global" do
-      defined?($1).should be_nil
-      defined?($4).should be_nil
-      defined?($7).should be_nil
-      defined?($10).should be_nil
-      defined?($200).should be_nil
+      defined?($1).should == nil
+      defined?($4).should == nil
+      defined?($7).should == nil
+      defined?($10).should == nil
+      defined?($200).should == nil
     end
   end
 
@@ -587,10 +765,10 @@ describe "The defined? keyword for variables" do
     end
 
     it "returns nil for non-captures" do
-      defined?($4).should be_nil
-      defined?($7).should be_nil
-      defined?($10).should be_nil
-      defined?($200).should be_nil
+      defined?($4).should == nil
+      defined?($7).should == nil
+      defined?($10).should == nil
+      defined?($200).should == nil
     end
   end
 
@@ -604,27 +782,27 @@ describe "The defined? keyword for variables" do
     end
 
     it "returns nil for $&" do
-      defined?($&).should be_nil
+      defined?($&).should == nil
     end
 
     it "returns nil for $`" do
-      defined?($`).should be_nil
+      defined?($`).should == nil
     end
 
     it "returns nil for $'" do
-      defined?($').should be_nil
+      defined?($').should == nil
     end
 
     it "returns nil for $+" do
-      defined?($+).should be_nil
+      defined?($+).should == nil
     end
 
     it "returns nil for any last match global" do
-      defined?($1).should be_nil
-      defined?($4).should be_nil
-      defined?($7).should be_nil
-      defined?($10).should be_nil
-      defined?($200).should be_nil
+      defined?($1).should == nil
+      defined?($4).should == nil
+      defined?($7).should == nil
+      defined?($10).should == nil
+      defined?($200).should == nil
     end
   end
 
@@ -659,10 +837,10 @@ describe "The defined? keyword for variables" do
     end
 
     it "returns nil for non-captures" do
-      defined?($4).should be_nil
-      defined?($7).should be_nil
-      defined?($10).should be_nil
-      defined?($200).should be_nil
+      defined?($4).should == nil
+      defined?($7).should == nil
+      defined?($10).should == nil
+      defined?($200).should == nil
     end
   end
   it "returns 'global-variable' for a global variable that has been assigned" do
@@ -670,7 +848,7 @@ describe "The defined? keyword for variables" do
   end
 
   it "returns nil for a class variable that has not been read" do
-    DefinedSpecs::Basic.new.class_variable_undefined.should be_nil
+    DefinedSpecs::Basic.new.class_variable_undefined.should == nil
   end
 
   # There is no spec for a class variable that is read before being assigned
@@ -678,7 +856,9 @@ describe "The defined? keyword for variables" do
   # get to the defined? call so it really has nothing to do with 'defined?'.
 
   it "returns 'class variable' when called with the name of a class variable" do
-    DefinedSpecs::Basic.new.class_variable_defined.should == "class variable"
+    ret = DefinedSpecs::Basic.new.class_variable_defined
+    ret.should == "class variable"
+    ret.frozen?.should == true
   end
 
   it "returns 'local-variable' when called with the name of a block local" do
@@ -689,16 +869,18 @@ end
 
 describe "The defined? keyword for a simple constant" do
   it "returns 'constant' when the constant is defined" do
-    defined?(DefinedSpecs).should == "constant"
+    ret = defined?(DefinedSpecs)
+    ret.should == "constant"
+    ret.frozen?.should == true
   end
 
   it "returns nil when the constant is not defined" do
-    defined?(DefinedSpecsUndefined).should be_nil
+    defined?(DefinedSpecsUndefined).should == nil
   end
 
   it "does not call Object.const_missing if the constant is not defined" do
     Object.should_not_receive(:const_missing)
-    defined?(DefinedSpecsUndefined).should be_nil
+    defined?(DefinedSpecsUndefined).should == nil
   end
 
   it "returns 'constant' for an included module" do
@@ -716,12 +898,12 @@ describe "The defined? keyword for a top-level constant" do
   end
 
   it "returns nil if the constant is not defined" do
-    defined?(::DefinedSpecsUndefined).should be_nil
+    defined?(::DefinedSpecsUndefined).should == nil
   end
 
   it "does not call Object.const_missing if the constant is not defined" do
     Object.should_not_receive(:const_missing)
-    defined?(::DefinedSpecsUndefined).should be_nil
+    defined?(::DefinedSpecsUndefined).should == nil
   end
 end
 
@@ -731,41 +913,37 @@ describe "The defined? keyword for a scoped constant" do
   end
 
   it "returns nil when the scoped constant is not defined" do
-    defined?(DefinedSpecs::Undefined).should be_nil
+    defined?(DefinedSpecs::Undefined).should == nil
+  end
+
+  it "returns nil when the constant is not defined and the outer module implements .const_missing" do
+    defined?(DefinedSpecs::ModuleWithConstMissing::Undefined).should == nil
   end
 
   it "does not call .const_missing if the constant is not defined" do
     DefinedSpecs.should_not_receive(:const_missing)
-    defined?(DefinedSpecs::UnknownChild).should be_nil
+    defined?(DefinedSpecs::UnknownChild).should == nil
   end
 
   it "returns nil when an undefined constant is scoped to a defined constant" do
-    defined?(DefinedSpecs::Child::Undefined).should be_nil
+    defined?(DefinedSpecs::Child::Undefined).should == nil
   end
 
   it "returns nil when a constant is scoped to an undefined constant" do
     Object.should_not_receive(:const_missing)
-    defined?(Undefined::Object).should be_nil
+    defined?(Undefined::Object).should == nil
   end
 
   it "returns nil when the undefined constant is scoped to an undefined constant" do
-    defined?(DefinedSpecs::Undefined::Undefined).should be_nil
+    defined?(DefinedSpecs::Undefined::Undefined).should == nil
   end
 
   it "returns nil when a constant is defined on top-level but not on the module" do
-    defined?(DefinedSpecs::String).should be_nil
+    defined?(DefinedSpecs::String).should == nil
   end
 
-  ruby_version_is ""..."2.5" do
-    it "returns 'constant' when a constant is defined on top-level but not on the class" do
-      defined?(DefinedSpecs::Basic::String).should == 'constant'
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "returns nil when a constant is defined on top-level but not on the class" do
-      defined?(DefinedSpecs::Basic::String).should be_nil
-    end
+  it "returns nil when a constant is defined on top-level but not on the class" do
+    defined?(DefinedSpecs::Basic::String).should == nil
   end
 
   it "returns 'constant' if the scoped-scoped constant is defined" do
@@ -779,15 +957,15 @@ describe "The defined? keyword for a top-level scoped constant" do
   end
 
   it "returns nil when the scoped constant is not defined" do
-    defined?(::DefinedSpecs::Undefined).should be_nil
+    defined?(::DefinedSpecs::Undefined).should == nil
   end
 
   it "returns nil when an undefined constant is scoped to a defined constant" do
-    defined?(::DefinedSpecs::Child::Undefined).should be_nil
+    defined?(::DefinedSpecs::Child::Undefined).should == nil
   end
 
   it "returns nil when the undefined constant is scoped to an undefined constant" do
-    defined?(::DefinedSpecs::Undefined::Undefined).should be_nil
+    defined?(::DefinedSpecs::Undefined::Undefined).should == nil
   end
 
   it "returns 'constant' if the scoped-scoped constant is defined" do
@@ -797,7 +975,7 @@ end
 
 describe "The defined? keyword for a self-send method call scoped constant" do
   it "returns nil if the constant is not defined in the scope of the method's value" do
-    defined?(defined_specs_method::Undefined).should be_nil
+    defined?(defined_specs_method::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant is defined in the scope of the method's value" do
@@ -805,11 +983,11 @@ describe "The defined? keyword for a self-send method call scoped constant" do
   end
 
   it "returns nil if the last constant is not defined in the scope chain" do
-    defined?(defined_specs_method::Basic::Undefined).should be_nil
+    defined?(defined_specs_method::Basic::Undefined).should == nil
   end
 
   it "returns nil if the middle constant is not defined in the scope chain" do
-    defined?(defined_specs_method::Undefined::Undefined).should be_nil
+    defined?(defined_specs_method::Undefined::Undefined).should == nil
   end
 
   it "returns 'constant' if all the constants in the scope chain are defined" do
@@ -819,7 +997,7 @@ end
 
 describe "The defined? keyword for a receiver method call scoped constant" do
   it "returns nil if the constant is not defined in the scope of the method's value" do
-    defined?(defined_specs_receiver.defined_method::Undefined).should be_nil
+    defined?(defined_specs_receiver.defined_method::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant is defined in the scope of the method's value" do
@@ -827,11 +1005,11 @@ describe "The defined? keyword for a receiver method call scoped constant" do
   end
 
   it "returns nil if the last constant is not defined in the scope chain" do
-    defined?(defined_specs_receiver.defined_method::Basic::Undefined).should be_nil
+    defined?(defined_specs_receiver.defined_method::Basic::Undefined).should == nil
   end
 
   it "returns nil if the middle constant is not defined in the scope chain" do
-    defined?(defined_specs_receiver.defined_method::Undefined::Undefined).should be_nil
+    defined?(defined_specs_receiver.defined_method::Undefined::Undefined).should == nil
   end
 
   it "returns 'constant' if all the constants in the scope chain are defined" do
@@ -841,7 +1019,7 @@ end
 
 describe "The defined? keyword for a module method call scoped constant" do
   it "returns nil if the constant is not defined in the scope of the method's value" do
-    defined?(DefinedSpecs.defined_method::Undefined).should be_nil
+    defined?(DefinedSpecs.defined_method::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant scoped by the method's value is defined" do
@@ -849,11 +1027,11 @@ describe "The defined? keyword for a module method call scoped constant" do
   end
 
   it "returns nil if the last constant in the scope chain is not defined" do
-    defined?(DefinedSpecs.defined_method::Basic::Undefined).should be_nil
+    defined?(DefinedSpecs.defined_method::Basic::Undefined).should == nil
   end
 
   it "returns nil if the middle constant in the scope chain is not defined" do
-    defined?(DefinedSpecs.defined_method::Undefined::Undefined).should be_nil
+    defined?(DefinedSpecs.defined_method::Undefined::Undefined).should == nil
   end
 
   it "returns 'constant' if all the constants in the scope chain are defined" do
@@ -861,11 +1039,11 @@ describe "The defined? keyword for a module method call scoped constant" do
   end
 
   it "returns nil if the outer scope constant in the receiver is not defined" do
-    defined?(Undefined::DefinedSpecs.defined_method::Basic).should be_nil
+    defined?(Undefined::DefinedSpecs.defined_method::Basic).should == nil
   end
 
   it "returns nil if the scoped constant in the receiver is not defined" do
-    defined?(DefinedSpecs::Undefined.defined_method::Basic).should be_nil
+    defined?(DefinedSpecs::Undefined.defined_method::Basic).should == nil
   end
 
   it "returns 'constant' if all the constants in the receiver are defined" do
@@ -886,7 +1064,7 @@ describe "The defined? keyword for a variable scoped constant" do
 
   it "returns nil if the instance scoped constant is not defined" do
     @defined_specs_obj = DefinedSpecs::Basic
-    defined?(@defined_specs_obj::Undefined).should be_nil
+    defined?(@defined_specs_obj::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant is defined in the scope of the instance variable" do
@@ -896,7 +1074,7 @@ describe "The defined? keyword for a variable scoped constant" do
 
   it "returns nil if the global scoped constant is not defined" do
     $defined_specs_obj = DefinedSpecs::Basic
-    defined?($defined_specs_obj::Undefined).should be_nil
+    defined?($defined_specs_obj::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant is defined in the scope of the global variable" do
@@ -905,22 +1083,26 @@ describe "The defined? keyword for a variable scoped constant" do
   end
 
   it "returns nil if the class scoped constant is not defined" do
-    -> {
-      @@defined_specs_obj = DefinedSpecs::Basic
-      defined?(@@defined_specs_obj::Undefined).should be_nil
-    }.should complain(/class variable access from toplevel/)
+    eval(<<-END, binding, __FILE__, __LINE__)
+      class singleton_class::A
+        @@defined_specs_obj = DefinedSpecs::Basic
+        defined?(@@defined_specs_obj::Undefined).should == nil
+      end
+    END
   end
 
   it "returns 'constant' if the constant is defined in the scope of the class variable" do
-    -> {
-      @@defined_specs_obj = DefinedSpecs::Basic
-      defined?(@@defined_specs_obj::A).should == "constant"
-    }.should complain(/class variable access from toplevel/)
+    eval(<<-END, binding, __FILE__, __LINE__)
+      class singleton_class::A
+        @@defined_specs_obj = DefinedSpecs::Basic
+        defined?(@@defined_specs_obj::A).should == "constant"
+      end
+    END
   end
 
   it "returns nil if the local scoped constant is not defined" do
     defined_specs_obj = DefinedSpecs::Basic
-    defined?(defined_specs_obj::Undefined).should be_nil
+    defined?(defined_specs_obj::Undefined).should == nil
   end
 
   it "returns 'constant' if the constant is defined in the scope of the local variable" do
@@ -941,46 +1123,62 @@ end
 
 describe "The defined? keyword for yield" do
   it "returns nil if no block is passed to a method not taking a block parameter" do
-    DefinedSpecs::Basic.new.no_yield_block.should be_nil
+    DefinedSpecs::Basic.new.no_yield_block.should == nil
   end
 
   it "returns nil if no block is passed to a method taking a block parameter" do
-    DefinedSpecs::Basic.new.no_yield_block_parameter.should be_nil
+    DefinedSpecs::Basic.new.no_yield_block_parameter.should == nil
   end
 
   it "returns 'yield' if a block is passed to a method not taking a block parameter" do
-    DefinedSpecs::Basic.new.yield_block.should == "yield"
+    ret = DefinedSpecs::Basic.new.yield_block
+    ret.should == "yield"
+    ret.frozen?.should == true
   end
 
   it "returns 'yield' if a block is passed to a method taking a block parameter" do
     DefinedSpecs::Basic.new.yield_block_parameter.should == "yield"
   end
+
+  it "returns 'yield' when called within a block" do
+    def yielder
+      yield
+    end
+
+    def call_defined
+      yielder { defined?(yield) }
+    end
+
+    call_defined() { }.should == "yield"
+  end
 end
 
 describe "The defined? keyword for super" do
   it "returns nil when a superclass undef's the method" do
-    DefinedSpecs::ClassWithoutMethod.new.test.should be_nil
+    DefinedSpecs::ClassWithoutMethod.new.test.should == nil
   end
 
   describe "for a method taking no arguments" do
     it "returns nil when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_method_no_args.should be_nil
+      DefinedSpecs::Super.new.no_super_method_no_args.should == nil
     end
 
     it "returns nil from a block when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_method_block_no_args.should be_nil
+      DefinedSpecs::Super.new.no_super_method_block_no_args.should == nil
     end
 
     it "returns nil from a #define_method when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_define_method_no_args.should be_nil
+      DefinedSpecs::Super.new.no_super_define_method_no_args.should == nil
     end
 
     it "returns nil from a block in a #define_method when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_define_method_block_no_args.should be_nil
+      DefinedSpecs::Super.new.no_super_define_method_block_no_args.should == nil
     end
 
     it "returns 'super' when a superclass method exists" do
-      DefinedSpecs::Super.new.method_no_args.should == "super"
+      ret = DefinedSpecs::Super.new.method_no_args
+      ret.should == "super"
+      ret.frozen?.should == true
     end
 
     it "returns 'super' from a block when a superclass method exists" do
@@ -1002,19 +1200,19 @@ describe "The defined? keyword for super" do
 
   describe "for a method taking arguments" do
     it "returns nil when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_method_args.should be_nil
+      DefinedSpecs::Super.new.no_super_method_args.should == nil
     end
 
     it "returns nil from a block when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_method_block_args.should be_nil
+      DefinedSpecs::Super.new.no_super_method_block_args.should == nil
     end
 
     it "returns nil from a #define_method when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_define_method_args.should be_nil
+      DefinedSpecs::Super.new.no_super_define_method_args.should == nil
     end
 
     it "returns nil from a block in a #define_method when no superclass method exists" do
-      DefinedSpecs::Super.new.no_super_define_method_block_args.should be_nil
+      DefinedSpecs::Super.new.no_super_define_method_block_args.should == nil
     end
 
     it "returns 'super' when a superclass method exists" do
@@ -1049,7 +1247,7 @@ describe "The defined? keyword for instance variables" do
   end
 
   it "returns nil if not assigned" do
-    defined?(@unassigned_ivar).should be_nil
+    defined?(@unassigned_ivar).should == nil
   end
 end
 
diff --git a/spec/ruby/language/delegation_spec.rb b/spec/ruby/language/delegation_spec.rb
new file mode 100644
index 0000000000..3d917993f5
--- /dev/null
+++ b/spec/ruby/language/delegation_spec.rb
@@ -0,0 +1,162 @@
+require_relative '../spec_helper'
+require_relative 'fixtures/delegation'
+
+# Forwarding anonymous parameters
+describe "delegation with def(...)" do
+  it "delegates rest and kwargs" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate(...)
+        target(...)
+      end
+    RUBY
+
+    a.new.delegate(1, b: 2).should == [[1], {b: 2}, nil]
+  end
+
+  it "delegates a block literal" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate_block(...)
+        target_block(...)
+      end
+    RUBY
+
+    a.new.delegate_block(1, b: 2) { |x| x }.should == [{b: 2}, [1]]
+  end
+
+  it "delegates a block argument" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate(...)
+        target(...)
+      end
+    RUBY
+
+    block = proc {}
+    a.new.delegate(1, b: 2, &block).should == [[1], {b: 2}, block]
+  end
+
+  it "delegates with additional arguments" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate(...)
+        target(:first, :second, ...)
+      end
+    RUBY
+    a.new.delegate(1, b: 2).should == [[:first, :second, 1], {b: 2}, nil]
+  end
+
+  it "parses as open endless Range when brackets are omitted" do
+    a = Class.new(DelegationSpecs::Target)
+    suppress_warning do
+      a.class_eval(<<-RUBY)
+        def delegate(...)
+          target ...
+        end
+      RUBY
+    end
+
+    a.new.delegate(1, b: 2).should == Range.new([[], {}, nil], nil, true)
+  end
+end
+
+describe "delegation with def(x, ...)" do
+  it "delegates rest and kwargs" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate(x, ...)
+        target(...)
+      end
+    RUBY
+
+    a.new.delegate(0, 1, b: 2).should == [[1], {b: 2}, nil]
+  end
+
+  it "delegates a block literal" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate_block(x, ...)
+        target_block(...)
+      end
+    RUBY
+
+    a.new.delegate_block(0, 1, b: 2) { |x| x }.should == [{b: 2}, [1]]
+  end
+
+  it "delegates a block argument" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+      def delegate(...)
+        target(...)
+      end
+    RUBY
+
+    block = proc {}
+    a.new.delegate(1, b: 2, &block).should == [[1], {b: 2}, block]
+  end
+end
+
+describe "delegation with def(*)" do
+  it "delegates rest" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+    def delegate(*)
+      target(*)
+    end
+    RUBY
+
+    a.new.delegate(0, 1).should == [[0, 1], {}, nil]
+  end
+
+  context "within a block that accepts anonymous rest within a method that accepts anonymous rest" do
+    it "does not allow delegating rest" do
+      -> {
+        eval "def m(*); proc { |*| n(*) } end"
+      }.should.raise(SyntaxError, /anonymous rest parameter is also used within block/)
+    end
+  end
+end
+
+describe "delegation with def(**)" do
+  it "delegates kwargs" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+    def delegate(**)
+      target(**)
+    end
+    RUBY
+
+    a.new.delegate(a: 1) { |x| x }.should == [[], {a: 1}, nil]
+  end
+
+  context "within a block that accepts anonymous kwargs within a method that accepts anonymous kwargs" do
+    it "does not allow delegating kwargs" do
+      -> {
+        eval "def m(**); proc { |**| n(**) } end"
+      }.should.raise(SyntaxError, /anonymous keyword rest parameter is also used within block/)
+    end
+  end
+end
+
+describe "delegation with def(&)" do
+  it "delegates an anonymous block parameter" do
+    a = Class.new(DelegationSpecs::Target)
+    a.class_eval(<<-RUBY)
+    def delegate(&)
+      target(&)
+    end
+    RUBY
+
+    block = proc {}
+    a.new.delegate(&block).should == [[], {}, block]
+  end
+
+  context "within a block that accepts anonymous block within a method that accepts anonymous block" do
+    it "does not allow delegating a block" do
+      -> {
+        eval "def m(&); proc { |&| n(&) } end"
+      }.should.raise(SyntaxError, /anonymous block parameter is also used within block/)
+    end
+  end
+end
diff --git a/spec/ruby/language/encoding_spec.rb b/spec/ruby/language/encoding_spec.rb
index 5430c9cb98..116f53a77d 100644
--- a/spec/ruby/language/encoding_spec.rb
+++ b/spec/ruby/language/encoding_spec.rb
@@ -5,7 +5,7 @@ require_relative 'fixtures/coding_utf_8'
 
 describe "The __ENCODING__ pseudo-variable" do
   it "is an instance of Encoding" do
-    __ENCODING__.should be_kind_of(Encoding)
+    __ENCODING__.should.is_a?(Encoding)
   end
 
   it "is US-ASCII by default" do
@@ -13,15 +13,15 @@ describe "The __ENCODING__ pseudo-variable" do
   end
 
   it "is the evaluated strings's one inside an eval" do
-    eval("__ENCODING__".force_encoding("US-ASCII")).should == Encoding::US_ASCII
-    eval("__ENCODING__".force_encoding("BINARY")).should == Encoding::BINARY
+    eval("__ENCODING__".dup.force_encoding("US-ASCII")).should == Encoding::US_ASCII
+    eval("__ENCODING__".dup.force_encoding("BINARY")).should == Encoding::BINARY
   end
 
   it "is the encoding specified by a magic comment inside an eval" do
-    code = "# encoding: BINARY\n__ENCODING__".force_encoding("US-ASCII")
+    code = "# encoding: BINARY\n__ENCODING__".dup.force_encoding("US-ASCII")
     eval(code).should == Encoding::BINARY
 
-    code = "# encoding: us-ascii\n__ENCODING__".force_encoding("BINARY")
+    code = "# encoding: us-ascii\n__ENCODING__".dup.force_encoding("BINARY")
     eval(code).should == Encoding::US_ASCII
   end
 
@@ -31,6 +31,6 @@ describe "The __ENCODING__ pseudo-variable" do
   end
 
   it "raises a SyntaxError if assigned to" do
-    -> { eval("__ENCODING__ = 1") }.should raise_error(SyntaxError)
+    -> { eval("__ENCODING__ = 1") }.should.raise(SyntaxError)
   end
 end
diff --git a/spec/ruby/language/ensure_spec.rb b/spec/ruby/language/ensure_spec.rb
index a930bda36b..04ff0305ab 100644
--- a/spec/ruby/language/ensure_spec.rb
+++ b/spec/ruby/language/ensure_spec.rb
@@ -6,7 +6,7 @@ describe "An ensure block inside a begin block" do
     ScratchPad.record []
   end
 
-  it "is executed when an exception is raised in it's corresponding begin block" do
+  it "is executed when an exception is raised in its corresponding begin block" do
     -> {
       begin
         ScratchPad << :begin
@@ -14,12 +14,12 @@ describe "An ensure block inside a begin block" do
       ensure
         ScratchPad << :ensure
       end
-    }.should raise_error(EnsureSpec::Error)
+    }.should.raise(EnsureSpec::Error)
 
     ScratchPad.recorded.should == [:begin, :ensure]
   end
 
-  it "is executed when an exception is raised and rescued in it's corresponding begin block" do
+  it "is executed when an exception is raised and rescued in its corresponding begin block" do
     begin
       ScratchPad << :begin
       raise "An exception occurred!"
@@ -32,7 +32,7 @@ describe "An ensure block inside a begin block" do
     ScratchPad.recorded.should == [:begin, :rescue, :ensure]
   end
 
-  it "is executed even when a symbol is thrown in it's corresponding begin block" do
+  it "is executed even when a symbol is thrown in its corresponding begin block" do
     catch(:symbol) do
       begin
         ScratchPad << :begin
@@ -47,7 +47,7 @@ describe "An ensure block inside a begin block" do
     ScratchPad.recorded.should == [:begin, :ensure]
   end
 
-  it "is executed when nothing is raised or thrown in it's corresponding begin block" do
+  it "is executed when nothing is raised or thrown in its corresponding begin block" do
     begin
       ScratchPad << :begin
     rescue
@@ -74,9 +74,9 @@ describe "An ensure block inside a begin block" do
       ensure
         raise "from ensure"
       end
-    }.should raise_error(RuntimeError, "from ensure") do |e|
+    }.should.raise(RuntimeError, "from ensure") { |e|
       e.cause.message.should == "from block"
-    end
+    }
   end
 end
 
@@ -108,7 +108,7 @@ describe "An ensure block inside a method" do
   end
 
   it "is executed when an exception is raised in the method" do
-    -> { @obj.raise_in_method_with_ensure }.should raise_error(EnsureSpec::Error)
+    -> { @obj.raise_in_method_with_ensure }.should.raise(EnsureSpec::Error)
     @obj.executed.should == [:method, :ensure]
   end
 
@@ -149,13 +149,13 @@ describe "An ensure block inside a method" do
   it "overrides exception raised in rescue if raises exception itself" do
     -> {
       @obj.raise_in_rescue_and_raise_in_ensure
-    }.should raise_error(RuntimeError, "raised in ensure")
+    }.should.raise(RuntimeError, "raised in ensure")
   end
 
   it "suppresses exception raised in method if raises exception itself" do
     -> {
       @obj.raise_in_method_and_raise_in_ensure
-    }.should raise_error(RuntimeError, "raised in ensure")
+    }.should.raise(RuntimeError, "raised in ensure")
   end
 end
 
@@ -174,7 +174,7 @@ describe "An ensure block inside a class" do
           ScratchPad << :ensure
         end
       ruby
-    }.should raise_error(EnsureSpec::Error)
+    }.should.raise(EnsureSpec::Error)
 
     ScratchPad.recorded.should == [:class, :ensure]
   end
@@ -247,87 +247,100 @@ describe "An ensure block inside {} block" do
         ensure
         }
       ruby
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 end
 
-ruby_version_is "2.5" do
-  describe "An ensure block inside 'do end' block" do
-    before :each do
-      ScratchPad.record []
-    end
-
-    it "is executed when an exception is raised in it's corresponding begin block" do
-      -> {
-        eval(<<-ruby).call
-          lambda do
-            ScratchPad << :begin
-            raise EnsureSpec::Error
-          ensure
-            ScratchPad << :ensure
-          end
-        ruby
-      }.should raise_error(EnsureSpec::Error)
-
-      ScratchPad.recorded.should == [:begin, :ensure]
-    end
+describe "An ensure block inside 'do end' block" do
+  before :each do
+    ScratchPad.record []
+  end
 
-    it "is executed when an exception is raised and rescued in it's corresponding begin block" do
+  it "is executed when an exception is raised in its corresponding begin block" do
+    -> {
       eval(<<-ruby).call
         lambda do
           ScratchPad << :begin
-          raise "An exception occurred!"
-        rescue
-          ScratchPad << :rescue
+          raise EnsureSpec::Error
         ensure
           ScratchPad << :ensure
         end
       ruby
+    }.should.raise(EnsureSpec::Error)
 
-      ScratchPad.recorded.should == [:begin, :rescue, :ensure]
-    end
+    ScratchPad.recorded.should == [:begin, :ensure]
+  end
 
-    it "is executed even when a symbol is thrown in it's corresponding begin block" do
-      catch(:symbol) do
-        eval(<<-ruby).call
-          lambda do
-            ScratchPad << :begin
-            throw(:symbol)
-          rescue
-            ScratchPad << :rescue
-          ensure
-            ScratchPad << :ensure
-          end
-        ruby
+  it "is executed when an exception is raised and rescued in its corresponding begin block" do
+    eval(<<-ruby).call
+      lambda do
+        ScratchPad << :begin
+        raise "An exception occurred!"
+      rescue
+        ScratchPad << :rescue
+      ensure
+        ScratchPad << :ensure
       end
+    ruby
 
-      ScratchPad.recorded.should == [:begin, :ensure]
-    end
+    ScratchPad.recorded.should == [:begin, :rescue, :ensure]
+  end
 
-    it "is executed when nothing is raised or thrown in it's corresponding begin block" do
+  it "is executed even when a symbol is thrown in its corresponding begin block" do
+    catch(:symbol) do
       eval(<<-ruby).call
         lambda do
           ScratchPad << :begin
+          throw(:symbol)
         rescue
           ScratchPad << :rescue
         ensure
           ScratchPad << :ensure
         end
       ruby
-
-      ScratchPad.recorded.should == [:begin, :ensure]
     end
 
-    it "has no return value" do
-      result = eval(<<-ruby).call
-        lambda do
-          :begin
+    ScratchPad.recorded.should == [:begin, :ensure]
+  end
+
+  it "is executed when nothing is raised or thrown in its corresponding begin block" do
+    eval(<<-ruby).call
+      lambda do
+        ScratchPad << :begin
+      rescue
+        ScratchPad << :rescue
+      ensure
+        ScratchPad << :ensure
+      end
+    ruby
+
+    ScratchPad.recorded.should == [:begin, :ensure]
+  end
+
+  it "has no return value" do
+    result = eval(<<-ruby).call
+      lambda do
+        :begin
+      ensure
+        :ensure
+      end
+    ruby
+
+    result.should == :begin
+  end
+
+  ruby_version_is "3.4" do
+    it "does not introduce extra backtrace entries" do
+      def foo
+        begin
+          raise "oops"
         ensure
-          :ensure
+          return caller(0, 2) # rubocop:disable Lint/EnsureReturn
         end
-      ruby
-
-      result.should == :begin
+      end
+      line = __LINE__
+      foo[0].should =~ /#{__FILE__}:#{line-3}:in 'foo'/
+      foo[1].should =~ /#{__FILE__}:#{line+2}:in 'block/
     end
   end
 end
diff --git a/spec/ruby/language/execution_spec.rb b/spec/ruby/language/execution_spec.rb
index 4e0310946d..51bcde62e8 100644
--- a/spec/ruby/language/execution_spec.rb
+++ b/spec/ruby/language/execution_spec.rb
@@ -5,6 +5,45 @@ describe "``" do
     ip = 'world'
     `echo disc #{ip}`.should == "disc world\n"
   end
+
+  it "can be redefined and receive a frozen string as argument" do
+    called = false
+    runner = Object.new
+
+    runner.singleton_class.define_method(:`) do |str|
+      called = true
+
+      str.should == "test command"
+      str.frozen?.should == true
+    end
+
+    runner.instance_exec do
+      `test command`
+    end
+
+    called.should == true
+  end
+
+  it "the argument isn't frozen if it contains interpolation" do
+    called = false
+    runner = Object.new
+
+    runner.singleton_class.define_method(:`) do |str|
+      called = true
+
+      str.should == "test command"
+      str.frozen?.should == false
+      str << "mutated"
+    end
+
+    2.times do
+      runner.instance_exec do
+        `test #{:command}` # rubocop:disable Lint/LiteralInInterpolation
+      end
+    end
+
+    called.should == true
+  end
 end
 
 describe "%x" do
@@ -12,4 +51,43 @@ describe "%x" do
     ip = 'world'
     %x(echo disc #{ip}).should == "disc world\n"
   end
+
+  it "can be redefined and receive a frozen string as argument" do
+    called = false
+    runner = Object.new
+
+    runner.singleton_class.define_method(:`) do |str|
+      called = true
+
+      str.should == "test command"
+      str.frozen?.should == true
+    end
+
+    runner.instance_exec do
+      %x{test command}
+    end
+
+    called.should == true
+  end
+
+  it "the argument isn't frozen if it contains interpolation" do
+    called = false
+    runner = Object.new
+
+    runner.singleton_class.define_method(:`) do |str|
+      called = true
+
+      str.should == "test command"
+      str.frozen?.should == false
+      str << "mutated"
+    end
+
+    2.times do
+      runner.instance_exec do
+        %x{test #{:command}} # rubocop:disable Lint/LiteralInInterpolation
+      end
+    end
+
+    called.should == true
+  end
 end
diff --git a/spec/ruby/language/file_spec.rb b/spec/ruby/language/file_spec.rb
index 729dee1008..dd89ce2385 100644
--- a/spec/ruby/language/file_spec.rb
+++ b/spec/ruby/language/file_spec.rb
@@ -4,26 +4,18 @@ require_relative 'shared/__FILE__'
 
 describe "The __FILE__ pseudo-variable" do
   it "raises a SyntaxError if assigned to" do
-    -> { eval("__FILE__ = 1") }.should raise_error(SyntaxError)
+    -> { eval("__FILE__ = 1") }.should.raise(SyntaxError)
   end
 
-  it "equals (eval) inside an eval" do
-    eval("__FILE__").should == "(eval)"
+  it "equals (eval at __FILE__:__LINE__) inside an eval" do
+    eval("__FILE__").should == "(eval at #{__FILE__}:#{__LINE__})"
   end
 end
 
-describe "The __FILE__ pseudo-variable" do
-  it_behaves_like :language___FILE__, :require, CodeLoadingSpecs::Method.new
-end
-
-describe "The __FILE__ pseudo-variable" do
+describe "The __FILE__ pseudo-variable with require" do
   it_behaves_like :language___FILE__, :require, Kernel
 end
 
-describe "The __FILE__ pseudo-variable" do
-  it_behaves_like :language___FILE__, :load, CodeLoadingSpecs::Method.new
-end
-
-describe "The __FILE__ pseudo-variable" do
+describe "The __FILE__ pseudo-variable with load" do
   it_behaves_like :language___FILE__, :load, Kernel
 end
diff --git a/spec/ruby/language/fixtures/class_with_class_variable.rb b/spec/ruby/language/fixtures/class_with_class_variable.rb
new file mode 100644
index 0000000000..0b07f16d30
--- /dev/null
+++ b/spec/ruby/language/fixtures/class_with_class_variable.rb
@@ -0,0 +1,9 @@
+module StringSpecs
+  class ClassWithClassVariable
+    @@a = "xxx"
+
+    def foo
+      "#@@a"
+    end
+  end
+end
diff --git a/spec/ruby/language/fixtures/constant_visibility.rb b/spec/ruby/language/fixtures/constant_visibility.rb
index 022554430e..af38b2d8f2 100644
--- a/spec/ruby/language/fixtures/constant_visibility.rb
+++ b/spec/ruby/language/fixtures/constant_visibility.rb
@@ -65,7 +65,7 @@ module ConstantVisibility
     end
   end
 
-  class PrivConstModuleChild
+  class ClassIncludingPrivConstModule
     include PrivConstModule
 
     def private_constant_from_include
@@ -77,6 +77,22 @@ module ConstantVisibility
     end
   end
 
+  module ModuleIncludingPrivConstModule
+    include PrivConstModule
+
+    def self.private_constant_from_include
+      PRIVATE_CONSTANT_MODULE
+    end
+
+    def self.private_constant_self_from_include
+      self::PRIVATE_CONSTANT_MODULE
+    end
+
+    def self.private_constant_named_from_include
+      PrivConstModule::PRIVATE_CONSTANT_MODULE
+    end
+  end
+
   class PrivConstClassChild < PrivConstClass
     def private_constant_from_subclass
       PRIVATE_CONSTANT_CLASS
diff --git a/spec/ruby/language/fixtures/defined.rb b/spec/ruby/language/fixtures/defined.rb
index 8b6004c19f..15bd7c50cf 100644
--- a/spec/ruby/language/fixtures/defined.rb
+++ b/spec/ruby/language/fixtures/defined.rb
@@ -19,6 +19,9 @@ module DefinedSpecs
     DefinedSpecs
   end
 
+  def self.any_args(*)
+  end
+
   class Basic
     A = 42
 
@@ -282,6 +285,12 @@ module DefinedSpecs
     end
   end
 
+  module ModuleWithConstMissing
+    def self.const_missing(const)
+      const
+    end
+  end
+
   class SuperWithIntermediateModules
     include IntermediateModule1
     include IntermediateModule2
@@ -290,6 +299,33 @@ module DefinedSpecs
       super
     end
   end
+
+  class ProtectedBase
+    def m; end
+    protected :m
+    def defined_on(o)
+      defined?(o.m)
+    end
+  end
+
+  class ProtectedSubclass < ProtectedBase
+  end
+
+  module ProtectedInModule
+    def m; end
+    protected :m
+    def defined_on(o)
+      defined?(o.m)
+    end
+  end
+
+  class ProtectedIncluderA
+    include ProtectedInModule
+  end
+
+  class ProtectedIncluderB
+    include ProtectedInModule
+  end
 end
 
 class Object
diff --git a/spec/ruby/language/fixtures/delegation.rb b/spec/ruby/language/fixtures/delegation.rb
new file mode 100644
index 0000000000..da2b024791
--- /dev/null
+++ b/spec/ruby/language/fixtures/delegation.rb
@@ -0,0 +1,11 @@
+module DelegationSpecs
+  class Target
+    def target(*args, **kwargs, &block)
+      [args, kwargs, block]
+    end
+
+    def target_block(*args, **kwargs)
+      yield [kwargs, args]
+    end
+  end
+end
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_across_files.rb b/spec/ruby/language/fixtures/freeze_magic_comment_across_files.rb
index 3aed2f29b6..f3ef666a3c 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_across_files.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_across_files.rb
@@ -2,4 +2,5 @@
 
 require_relative 'freeze_magic_comment_required'
 
-p "abc".object_id == $second_literal_id
+p "abc".equal?($second_literal)
+$second_literal = nil
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_across_files_diff_enc.rb b/spec/ruby/language/fixtures/freeze_magic_comment_across_files_diff_enc.rb
index 53ef959970..e9ca35e7c8 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_across_files_diff_enc.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_across_files_diff_enc.rb
@@ -2,4 +2,5 @@
 
 require_relative 'freeze_magic_comment_required_diff_enc'
 
-p "abc".object_id != $second_literal_id
+p !"abc".equal?($second_literal)
+$second_literal = nil
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_across_files_no_comment.rb b/spec/ruby/language/fixtures/freeze_magic_comment_across_files_no_comment.rb
index fc6cd5bf82..c9eaab46a2 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_across_files_no_comment.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_across_files_no_comment.rb
@@ -2,4 +2,5 @@
 
 require_relative 'freeze_magic_comment_required_no_comment'
 
-p "abc".object_id != $second_literal_id
+p !"abc".equal?($second_literal)
+$second_literal = nil
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_one_literal.rb b/spec/ruby/language/fixtures/freeze_magic_comment_one_literal.rb
index d35905b332..c175b2b7a2 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_one_literal.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_one_literal.rb
@@ -1,4 +1,4 @@
 # frozen_string_literal: true
 
-ids = Array.new(2) { "abc".object_id }
-p ids.first == ids.last
+objs = Array.new(2) { "abc" }
+p objs.first.equal?(objs.last)
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_required.rb b/spec/ruby/language/fixtures/freeze_magic_comment_required.rb
index a4ff4459b1..f75acb2ce3 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_required.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_required.rb
@@ -1,3 +1,3 @@
 # frozen_string_literal: true
 
-$second_literal_id = "abc".object_id
+$second_literal = "abc"
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_required_diff_enc.rb b/spec/ruby/language/fixtures/freeze_magic_comment_required_diff_enc.rb
index d0558a2251..739e96e99a 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_required_diff_enc.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_required_diff_enc.rb
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_required_no_comment.rb b/spec/ruby/language/fixtures/freeze_magic_comment_required_no_comment.rb
index e09232a5f4..6fbe175b42 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_required_no_comment.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_required_no_comment.rb
@@ -1 +1 @@
-$second_literal_id = "abc".object_id
+$second_literal = "abc"
diff --git a/spec/ruby/language/fixtures/freeze_magic_comment_two_literals.rb b/spec/ruby/language/fixtures/freeze_magic_comment_two_literals.rb
index a4d655ad02..cccc5969bd 100644
--- a/spec/ruby/language/fixtures/freeze_magic_comment_two_literals.rb
+++ b/spec/ruby/language/fixtures/freeze_magic_comment_two_literals.rb
@@ -1,3 +1,3 @@
 # frozen_string_literal: true
 
-p "abc".object_id == "abc".object_id
+p "abc".equal?("abc")
diff --git a/spec/ruby/language/fixtures/module.rb b/spec/ruby/language/fixtures/module.rb
index 33d323846e..75eee77791 100644
--- a/spec/ruby/language/fixtures/module.rb
+++ b/spec/ruby/language/fixtures/module.rb
@@ -12,13 +12,4 @@ module ModuleSpecs
 
   module Anonymous
   end
-
-  module IncludedInObject
-    module IncludedModuleSpecs
-    end
-  end
-end
-
-class Object
-  include ModuleSpecs::IncludedInObject
 end
diff --git a/spec/ruby/language/fixtures/private.rb b/spec/ruby/language/fixtures/private.rb
index 96f73cea3f..da3e0a97f9 100644
--- a/spec/ruby/language/fixtures/private.rb
+++ b/spec/ruby/language/fixtures/private.rb
@@ -43,17 +43,17 @@ module Private
     end
   end
 
-   class E
-     include D
-   end
-
-   class G
-     def foo
-       "foo"
-     end
-   end
-
-   class H < A
-     private :foo
-   end
+  class E
+    include D
+  end
+
+  class G
+    def foo
+      "foo"
+    end
+  end
+
+  class H < A
+    private :foo
+  end
 end
diff --git a/spec/ruby/language/fixtures/rescue/top_level.rb b/spec/ruby/language/fixtures/rescue/top_level.rb
new file mode 100644
index 0000000000..59e78ef1d6
--- /dev/null
+++ b/spec/ruby/language/fixtures/rescue/top_level.rb
@@ -0,0 +1,7 @@
+# capturing in local variable at top-level
+
+begin
+  raise "message"
+rescue => e
+  ScratchPad << e.message
+end
diff --git a/spec/ruby/language/fixtures/rescue_captures.rb b/spec/ruby/language/fixtures/rescue_captures.rb
new file mode 100644
index 0000000000..69f9b83904
--- /dev/null
+++ b/spec/ruby/language/fixtures/rescue_captures.rb
@@ -0,0 +1,107 @@
+module RescueSpecs
+  class Captor
+    attr_accessor :captured_error
+
+    def self.should_capture_exception
+      captor = new
+      captor.capture('some text').should == :caught # Ensure rescue body still runs
+      captor.captured_error.message.should == 'some text'
+    end
+  end
+
+  class ClassVariableCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => @@captured_error
+      :caught
+    end
+
+    def captured_error
+      self.class.remove_class_variable(:@@captured_error)
+    end
+  end
+
+  class ConstantCaptor < Captor
+    # Using lambda gets around the dynamic constant assignment warning
+    CAPTURE = -> msg {
+      begin
+        raise msg
+      rescue => CapturedError
+        :caught
+      end
+    }
+
+    def capture(msg)
+      CAPTURE.call(msg)
+    end
+
+    def captured_error
+      self.class.send(:remove_const, :CapturedError)
+    end
+  end
+
+  class GlobalVariableCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => $captured_error
+      :caught
+    end
+
+    def captured_error
+      $captured_error.tap do
+        $captured_error = nil # Can't remove globals, only nil them out
+      end
+    end
+  end
+
+  class InstanceVariableCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => @captured_error
+      :caught
+    end
+  end
+
+  class LocalVariableCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => captured_error
+      @captured_error = captured_error
+      :caught
+    end
+  end
+
+  class SafeNavigationSetterCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => self&.captured_error
+      :caught
+    end
+  end
+
+  class SetterCaptor < Captor
+    def capture(msg)
+      raise msg
+    rescue => self.captured_error
+      :caught
+    end
+  end
+
+  class SquareBracketsCaptor < Captor
+    def capture(msg)
+      @hash = {}
+
+      raise msg
+    rescue => self[:error]
+      :caught
+    end
+
+    def []=(key, value)
+      @hash[key] = value
+    end
+
+    def captured_error
+      @hash[:error]
+    end
+  end
+end
diff --git a/spec/ruby/language/fixtures/return.rb b/spec/ruby/language/fixtures/return.rb
index 0414c356e8..f6b143f3fa 100644
--- a/spec/ruby/language/fixtures/return.rb
+++ b/spec/ruby/language/fixtures/return.rb
@@ -101,18 +101,14 @@ module ReturnSpecs
       # return value will go into val before we run the ensure.
       #
       # If lamb's return keeps unwinding incorrectly, val will still
-      # have it's old value.
+      # have its old value.
       #
       # We can therefore use val to figure out what happened.
       begin
         val = foo()
       ensure
-        if val != :good
-          return :bad
-        end
+        return val
       end
-
-      return val
     end
   end
 
diff --git a/spec/ruby/language/fixtures/send.rb b/spec/ruby/language/fixtures/send.rb
index 918241e171..4787abee5c 100644
--- a/spec/ruby/language/fixtures/send.rb
+++ b/spec/ruby/language/fixtures/send.rb
@@ -43,9 +43,9 @@ module LangSendSpecs
     attr_writer :foo
     private :foo=
 
-      def call_self_foo_equals(value)
-        self.foo = value
-      end
+    def call_self_foo_equals(value)
+      self.foo = value
+    end
 
     def call_self_foo_equals_masgn(value)
       a, self.foo = 1, value
@@ -81,6 +81,16 @@ module LangSendSpecs
     end
   end
 
+  class RawToProc
+    def initialize(to_proc)
+      @to_proc = to_proc
+    end
+
+    def to_proc
+      @to_proc
+    end
+  end
+
   class ToAry
     def initialize(obj)
       @obj = obj
diff --git a/spec/ruby/language/fixtures/squiggly_heredoc.rb b/spec/ruby/language/fixtures/squiggly_heredoc.rb
index afc87514c7..984a629e5b 100644
--- a/spec/ruby/language/fixtures/squiggly_heredoc.rb
+++ b/spec/ruby/language/fixtures/squiggly_heredoc.rb
@@ -29,6 +29,22 @@ module SquigglyHeredocSpecs
     HERE
   end
 
+  def self.backslash
+    <<~HERE
+      a
+      b\
+      c
+    HERE
+  end
+
+  def self.least_indented_on_the_first_line
+    <<~HERE
+      a
+        b
+          c
+    HERE
+  end
+
   def self.least_indented_on_the_last_line
     <<~HERE
           a
@@ -36,4 +52,20 @@ module SquigglyHeredocSpecs
       c
     HERE
   end
+
+  def self.least_indented_on_the_first_line_single
+    <<~'HERE'
+      a
+        b
+          c
+    HERE
+  end
+
+  def self.least_indented_on_the_last_line_single
+    <<~'HERE'
+          a
+        b
+      c
+    HERE
+  end
 end
diff --git a/spec/ruby/language/fixtures/super.rb b/spec/ruby/language/fixtures/super.rb
index 6a024cae23..b6d4218b03 100644
--- a/spec/ruby/language/fixtures/super.rb
+++ b/spec/ruby/language/fixtures/super.rb
@@ -266,7 +266,7 @@ module SuperSpecs
 
       # Use this so that we can see collect all supers that we see.
       # One bug that arises is that we call Alias2#name from Alias2#name
-      # as it's superclass. In that case, either we get a runaway recursion
+      # as its superclass. In that case, either we get a runaway recursion
       # super OR we get the return value being [:alias2, :alias2, :alias1]
       # rather than [:alias2, :alias1].
       #
@@ -455,6 +455,52 @@ module SuperSpecs
     end
   end
 
+  module ZSuperWithRestAndPost
+    class A
+      def m(*args, a, b)
+        args
+      end
+
+      def m_modified(*args, a, b)
+        args
+      end
+    end
+
+    class B < A
+      def m(*args, a, b)
+        super
+      end
+
+      def m_modified(*args, a, b)
+        args[1] = 14
+        super
+      end
+    end
+  end
+
+  module ZSuperWithRestOthersAndPost
+    class A
+      def m(a, *args, b)
+        args
+      end
+
+      def m_modified(a, *args, b)
+        args
+      end
+    end
+
+    class B < A
+      def m(a, *args, b)
+        super
+      end
+
+      def m_modified(a, *args, b)
+        args[1] = 14
+        super
+      end
+    end
+  end
+
   module ZSuperWithRestReassigned
     class A
       def a(*args)
@@ -493,6 +539,30 @@ module SuperSpecs
         args
       end
 
+      def m3(*args)
+        args
+      end
+
+      def m4(*args)
+        args
+      end
+
+      def m_default(*args)
+        args
+      end
+
+      def m_rest(*args)
+        args
+      end
+
+      def m_pre_default_rest_post(*args)
+        args
+      end
+
+      def m_kwrest(**kw)
+        kw
+      end
+
       def m_modified(*args)
         args
       end
@@ -503,6 +573,30 @@ module SuperSpecs
         super
       end
 
+      def m3(_, _, _)
+        super
+      end
+
+      def m4(_, _, _, _)
+        super
+      end
+
+      def m_default(_ = 0)
+        super
+      end
+
+      def m_rest(*_)
+        super
+      end
+
+      def m_pre_default_rest_post(_, _, _=:a, _=:b, *_, _, _)
+        super
+      end
+
+      def m_kwrest(**_)
+        super
+      end
+
       def m_modified(_, _)
         _ = 14
         super
@@ -510,6 +604,20 @@ module SuperSpecs
     end
   end
 
+  module ZSuperInBlock
+    class A
+      def m(arg:)
+        arg
+      end
+    end
+
+    class B < A
+      def m(arg:)
+        proc { super }.call
+      end
+    end
+  end
+
   module Keywords
     class Arguments
       def foo(**args)
diff --git a/spec/ruby/language/fixtures/variables.rb b/spec/ruby/language/fixtures/variables.rb
index 07265dbb2b..527caa7a78 100644
--- a/spec/ruby/language/fixtures/variables.rb
+++ b/spec/ruby/language/fixtures/variables.rb
@@ -82,4 +82,76 @@ module VariablesSpecs
   def self.false
     false
   end
+
+  class EvalOrder
+    attr_reader :order
+
+    def initialize
+      @order = []
+    end
+
+    def reset
+      @order = []
+    end
+
+    def foo
+      self << "foo"
+      FooClass.new(self)
+    end
+
+    def bar
+      self << "bar"
+      BarClass.new(self)
+    end
+
+    def a
+      self << "a"
+    end
+
+    def b
+      self << "b"
+    end
+
+    def node
+      self << "node"
+
+      node = Node.new
+      node.left = Node.new
+      node.left.right = Node.new
+
+      node
+    end
+
+    def <<(value)
+      order << value
+    end
+
+    class FooClass
+      attr_reader :evaluator
+
+      def initialize(evaluator)
+        @evaluator = evaluator
+      end
+
+      def []=(_index, _value)
+        evaluator << "foo[]="
+      end
+    end
+
+    class BarClass
+      attr_reader :evaluator
+
+      def initialize(evaluator)
+        @evaluator = evaluator
+      end
+
+      def baz=(_value)
+        evaluator << "bar.baz="
+      end
+    end
+
+    class Node
+      attr_accessor :left, :right
+    end
+  end
 end
diff --git a/spec/ruby/language/for_spec.rb b/spec/ruby/language/for_spec.rb
index 0ad5ea88af..b0f3aef405 100644
--- a/spec/ruby/language/for_spec.rb
+++ b/spec/ruby/language/for_spec.rb
@@ -19,6 +19,27 @@ describe "The for expression" do
     end
   end
 
+  it "iterates over a list of arrays and destructures with an empty splat" do
+    for i, * in [[1,2]]
+      i.should == 1
+    end
+  end
+
+  it "iterates over a list of arrays and destructures with a splat" do
+    for i, *j in [[1,2]]
+      i.should == 1
+      j.should == [2]
+    end
+  end
+
+  it "iterates over a list of arrays and destructures with a splat and additional targets" do
+    for i, *j, k in [[1,2,3,4]]
+      i.should == 1
+      j.should == [2,3]
+      k.should == 4
+    end
+  end
+
   it "iterates over an Hash passing each key-value pair to the block" do
     k = 0
     l = 0
@@ -81,6 +102,85 @@ describe "The for expression" do
     end
   end
 
+  it "allows a global variable as an iterator name" do
+    old_global_var = $var
+    m = [1,2,3]
+    n = 0
+    for $var in m
+      n += 1
+    end
+    $var.should == 3
+    n.should == 3
+    $var = old_global_var
+  end
+
+  it "allows an attribute as an iterator name" do
+    class OFor
+      attr_accessor :target
+    end
+
+    ofor = OFor.new
+    m = [1,2,3]
+    n = 0
+    for ofor.target in m
+      n += 1
+    end
+    ofor.target.should == 3
+    n.should == 3
+  end
+
+  it "allows an attribute with safe navigation as an iterator name" do
+    class OFor
+      attr_accessor :target
+    end
+
+    ofor = OFor.new
+    m = [1,2,3]
+    n = 0
+    eval <<~RUBY
+      for ofor&.target in m
+        n += 1
+      end
+    RUBY
+    ofor.target.should == 3
+    n.should == 3
+  end
+
+  it "allows an attribute with safe navigation on a nil base as an iterator name" do
+    ofor = nil
+    m = [1,2,3]
+    n = 0
+    eval <<~RUBY
+      for ofor&.target in m
+        n += 1
+      end
+    RUBY
+    ofor.should == nil
+    n.should == 3
+  end
+
+  it "allows an array index writer as an iterator name" do
+    arr = [:a, :b, :c]
+    m = [1,2,3]
+    n = 0
+    for arr[1] in m
+      n += 1
+    end
+    arr.should == [:a, 3, :c]
+    n.should == 3
+  end
+
+  it "allows a hash index writer as an iterator name" do
+    hash = { a: 10, b: 20, c: 30 }
+    m = [1,2,3]
+    n = 0
+    for hash[:b] in m
+      n += 1
+    end
+    hash.should == { a: 10, b: 3, c: 30 }
+    n.should == 3
+  end
+
   # 1.9 behaviour verified by nobu in
   # http://redmine.ruby-lang.org/issues/show/2053
   it "yields only as many values as there are arguments" do
@@ -115,7 +215,15 @@ describe "The for expression" do
     j.should == 6
   end
 
-  it "executes code in containing variable scope" do
+  it "declares iteration variables in the surrounding variable scope" do
+    for a, b in [[1,2]]
+    end
+
+    a.should == 1
+    b.should == 2
+  end
+
+  it "declares variables in the body in the surrounding variable scope" do
     for i in 1..2
       a = 123
     end
@@ -123,7 +231,7 @@ describe "The for expression" do
     a.should == 123
   end
 
-  it "executes code in containing variable scope with 'do'" do
+  it "declares variables in the body in the surrounding variable scope with 'do'" do
     for i in 1..2 do
       a = 123
     end
@@ -131,6 +239,96 @@ describe "The for expression" do
     a.should == 123
   end
 
+  it "declares variables inside a block as normal" do
+    for i in 1..2 do
+      proc {
+        inside_proc = 42
+      }.call
+    end
+    local_variables.should == [:i]
+  end
+
+  it "declares variables inside a lambda as normal" do
+    for i in 1..2 do
+      -> {
+        inside_proc = 42
+      }.call
+    end
+    local_variables.should == [:i]
+  end
+
+  it "can be nested" do
+    for a in [6]
+      for b in [7]
+        c = a * b
+      end
+    end
+    local_variables.sort.should == [:a, :b, :c]
+    c.should == 42
+  end
+
+  it "can be nested with blocks in between" do
+    # This is an edge case spec for Ruby implementations which have
+    # their own runtime scope per for loop body (like YARV and TruffleRuby)
+    for a in [1]
+      a1 = a
+      a1.should == a
+      for b in [2]
+        b1 = b
+        a1.should == a
+        b1.should == b
+        proc {
+          inside_proc = 42
+
+          a1.should == a
+          b1.should == b
+          inside_proc.should == 42
+
+          for c in [3].map { |enum_var|
+            a1.should == a
+            b1.should == b
+            inside_proc.should == 42
+            enum_var
+          }
+            c1 = c
+
+            a1.should == a
+            b1.should == b
+            c1.should == c
+            inside_proc.should == 42
+
+            for d in [4]
+              d1 = d
+
+              a1.should == a
+              b1.should == b
+              c1.should == c
+              d1.should == d
+              inside_proc.should == 42
+            end
+          end
+          local_variables.sort.should == [:a, :a1, :b, :b1, :c, :c1, :d, :d1, :inside_proc]
+        }.call
+      end
+    end
+    local_variables.sort.should == [:a, :a1, :b, :b1]
+  end
+
+  it "can be nested with forward arguments" do
+    def bar(*args)
+      args
+    end
+
+    def foo(...)
+      for a in [1]
+        r = bar(...)
+      end
+      r
+    end
+
+    foo(2, 3).should == [2, 3]
+  end
+
   it "does not try to access variables outside the method" do
     ForSpecs::ForInClassMethod.foo.should == [:bar, :baz]
     ForSpecs::ForInClassMethod::READER.call.should == :same_variable_set_outside
diff --git a/spec/ruby/language/hash_spec.rb b/spec/ruby/language/hash_spec.rb
index 6f2e8e5cf0..7a4a2e37c9 100644
--- a/spec/ruby/language/hash_spec.rb
+++ b/spec/ruby/language/hash_spec.rb
@@ -33,12 +33,12 @@ describe "Hash literal" do
   end
 
   it "freezes string keys on initialization" do
-    key = "foo"
+    key = +"foo"
     h = {key => "bar"}
     key.reverse!
     h["foo"].should == "bar"
     h.keys.first.should == "foo"
-    h.keys.first.frozen?.should == true
+    h.keys.first.should.frozen?
     key.should == "oof"
   end
 
@@ -48,6 +48,24 @@ describe "Hash literal" do
     }.should complain(/key :foo is duplicated|duplicated key/)
     @h.keys.size.should == 1
     @h.should == {foo: :foo}
+    -> {
+      @h = eval "{%q{a} => :bar, %q{a} => :foo}"
+    }.should complain(/key "a" is duplicated|duplicated key/)
+    @h.keys.size.should == 1
+    @h.should == {%q{a} => :foo}
+    -> {
+      @h = eval "{1000 => :bar, 1000 => :foo}"
+    }.should complain(/key 1000 is duplicated|duplicated key/)
+    @h.keys.size.should == 1
+    @h.should == {1000 => :foo}
+  end
+
+  it "checks duplicated float keys on initialization" do
+    -> {
+      @h = eval "{1.0 => :bar, 1.0 => :foo}"
+    }.should complain(/key 1.0 is duplicated|duplicated key/)
+    @h.keys.size.should == 1
+    @h.should == {1.0 => :foo}
   end
 
   it "accepts a hanging comma" do
@@ -57,13 +75,37 @@ describe "Hash literal" do
   end
 
   it "recognizes '=' at the end of the key" do
-    eval("{:a==>1}").should == {:"a=" => 1}
-    eval("{:a= =>1}").should == {:"a=" => 1}
-    eval("{:a= => 1}").should == {:"a=" => 1}
+    {:a==>1}.should == {:"a=" => 1}
+    {:a= =>1}.should == {:"a=" => 1}
+    {:a= => 1}.should == {:"a=" => 1}
   end
 
   it "with '==>' in the middle raises SyntaxError" do
-    -> { eval("{:a ==> 1}") }.should raise_error(SyntaxError)
+    -> { eval("{:a ==> 1}") }.should.raise(SyntaxError)
+  end
+
+  it "recognizes '!' at the end of the key" do
+    {:a! =>1}.should == {:"a!" => 1}
+    {:a! => 1}.should == {:"a!" => 1}
+
+    {a!:1}.should == {:"a!" => 1}
+    {a!: 1}.should == {:"a!" => 1}
+  end
+
+  it "raises a SyntaxError if there is no space between `!` and `=>`" do
+    -> { eval("{:a!=> 1}") }.should.raise(SyntaxError)
+  end
+
+  it "recognizes '?' at the end of the key" do
+    {:a? =>1}.should == {:"a?" => 1}
+    {:a? => 1}.should == {:"a?" => 1}
+
+    {a?:1}.should == {:"a?" => 1}
+    {a?: 1}.should == {:"a?" => 1}
+  end
+
+  it "raises a SyntaxError if there is no space between `?` and `=>`" do
+    -> { eval("{:a?=> 1}") }.should.raise(SyntaxError)
   end
 
   it "constructs a new hash with the given elements" do
@@ -85,7 +127,7 @@ describe "Hash literal" do
 
   it "accepts mixed 'key: value', 'key => value' and '\"key\"': value' syntax" do
     h = {:a => 1, :b => 2, "c" => 3, :d => 4}
-    eval('{a: 1, :b => 2, "c" => 3, "d": 4}').should == h
+    {a: 1, :b => 2, "c" => 3, "d": 4}.should == h
   end
 
   it "expands an '**{}' element into the containing Hash literal initialization" do
@@ -107,11 +149,55 @@ describe "Hash literal" do
     {a: 1, **h, c: 4}.should == {a: 1, b: 2, c: 4}
   end
 
-  it "expands an '**{}' element with the last key/value pair taking precedence" do
+  ruby_version_is ""..."3.4" do
+    it "does not expand nil using ** into {} and raises TypeError" do
+      h = nil
+      -> { {a: 1, **h} }.should.raise(TypeError, "no implicit conversion of nil into Hash")
+
+      -> { {a: 1, **nil} }.should.raise(TypeError, "no implicit conversion of nil into Hash")
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "expands nil using ** into {}" do
+      h = nil
+      {**h}.should == {}
+      {a: 1, **h}.should == {a: 1}
+
+      {**nil}.should == {}
+      {a: 1, **nil}.should == {a: 1}
+    end
+
+    it "expands nil using ** into {} and provides a copy to the callable" do
+      ScratchPad.record []
+      insert = -> key, **kw do
+        kw[key] = 1
+        ScratchPad << kw
+      end
+      insert.call(:foo, **nil)
+      insert.call(:bar, **nil)
+      ScratchPad.recorded.should == [{ foo: 1 }, { bar: 1 }]
+    end
+  end
+
+  it "expands an '**{}' or '**obj' element with the last key/value pair taking precedence" do
     -> {
       @h = eval "{a: 1, **{a: 2, b: 3, c: 1}, c: 3}"
     }.should complain(/key :a is duplicated|duplicated key/)
     @h.should == {a: 2, b: 3, c: 3}
+
+    -> {
+      h = {a: 2, b: 3, c: 1}
+      @h = eval "{a: 1, **h, c: 3}"
+    }.should_not complain
+    @h.should == {a: 2, b: 3, c: 3}
+  end
+
+  it "expands an '**{}' and warns when finding an additional duplicate key afterwards" do
+    -> {
+      @h = eval "{d: 1, **{a: 2, b: 3, c: 1}, c: 3}"
+    }.should complain(/key :c is duplicated|duplicated key/)
+    @h.should == {a: 2, b: 3, c: 3, d: 1}
   end
 
   it "merges multiple nested '**obj' in Hash literals" do
@@ -128,25 +214,22 @@ describe "Hash literal" do
     {a: 1, **obj, c: 3}.should == {a:1, b: 2, c: 3, d: 4}
   end
 
-  ruby_version_is ""..."2.7" do
-    it "raises a TypeError if any splatted elements keys are not symbols" do
-      h = {1 => 2, b: 3}
-      -> { {a: 1, **h} }.should raise_error(TypeError)
-    end
-  end
-
-  ruby_version_is "2.7" do
-    it "allows splatted elements keys that are not symbols" do
-      h = {1 => 2, b: 3}
-      {a: 1, **h}.should == {a: 1, 1 => 2, b: 3}
-    end
+  it "allows splatted elements keys that are not symbols" do
+    h = {1 => 2, b: 3}
+    {a: 1, **h}.should == {a: 1, 1 => 2, b: 3}
   end
 
   it "raises a TypeError if #to_hash does not return a Hash" do
     obj = mock("hash splat")
     obj.should_receive(:to_hash).and_return(obj)
 
-    -> { {**obj} }.should raise_error(TypeError)
+    -> { {**obj} }.should.raise(TypeError)
+  end
+
+  it "raises a TypeError if the object does not respond to #to_hash" do
+    obj = 42
+    -> { {**obj} }.should.raise(TypeError)
+    -> { {a: 1, **obj} }.should.raise(TypeError)
   end
 
   it "does not change encoding of literal string keys during creation" do
@@ -160,4 +243,91 @@ describe "Hash literal" do
     utf8_hash.keys.first.should == usascii_hash.keys.first
     usascii_hash.keys.first.encoding.should == Encoding::US_ASCII
   end
+
+  ruby_bug "#20280", ""..."3.4" do
+    it "raises a SyntaxError at parse time when Symbol key with invalid bytes" do
+      ScratchPad.record []
+      -> {
+        eval 'ScratchPad << 1; {:"\xC3" => 1}'
+      }.should.raise(SyntaxError, /invalid symbol/)
+      ScratchPad.recorded.should == []
+    end
+
+    it "raises a SyntaxError at parse time when Symbol key with invalid bytes and 'key: value' syntax used" do
+      ScratchPad.record []
+      -> {
+        eval 'ScratchPad << 1; {"\xC3": 1}'
+      }.should.raise(SyntaxError, /invalid symbol/)
+      ScratchPad.recorded.should == []
+    end
+  end
+end
+
+describe "The ** operator" do
+  it "makes a copy when calling a method taking a keyword rest argument" do
+    def m(**h)
+      h.delete(:one); h
+    end
+
+    h = { one: 1, two: 2 }
+    m(**h).should == { two: 2 }
+    m(**h).should_not.equal?(h)
+    h.should == { one: 1, two: 2 }
+  end
+
+  it "makes a copy when calling a method taking a positional Hash" do
+    def m(h)
+      h.delete(:one); h
+    end
+
+    h = { one: 1, two: 2 }
+    m(**h).should == { two: 2 }
+    m(**h).should_not.equal?(h)
+    h.should == { one: 1, two: 2 }
+  end
+
+  describe "hash with omitted value" do
+    it "accepts short notation 'key' for 'key: value' syntax" do
+      a, b, c = 1, 2, 3
+      h = {a:}
+      {a: 1}.should == h
+      h = {a:, b:, c:}
+      {a: 1, b: 2, c: 3}.should == h
+    end
+
+    it "ignores hanging comma on short notation" do
+      a, b, c = 1, 2, 3
+      h = {a:, b:, c:,}
+      {a: 1, b: 2, c: 3}.should == h
+    end
+
+    it "accepts mixed syntax" do
+      a, e = 1, 5
+      h = {a:, b: 2, "c" => 3, :d => 4, e:}
+      {a: 1, :b => 2, "c" => 3, "d": 4, e: 5}.should == h
+    end
+
+    it "works with methods and local vars" do
+      a = Class.new
+      a.class_eval(<<-RUBY)
+        def bar
+          "baz"
+        end
+
+        def foo(val)
+          {bar:, val:}
+        end
+      RUBY
+
+      a.new.foo(1).should == {bar: "baz", val: 1}
+    end
+
+    it "raises a SyntaxError when the hash key ends with `!`" do
+      -> { eval("{a!:}") }.should.raise(SyntaxError, /identifier a! is not valid to get/)
+    end
+
+    it "raises a SyntaxError when the hash key ends with `?`" do
+      -> { eval("{a?:}") }.should.raise(SyntaxError, /identifier a\? is not valid to get/)
+    end
+  end
 end
diff --git a/spec/ruby/language/heredoc_spec.rb b/spec/ruby/language/heredoc_spec.rb
index e7655a9216..535f18cba8 100644
--- a/spec/ruby/language/heredoc_spec.rb
+++ b/spec/ruby/language/heredoc_spec.rb
@@ -59,6 +59,12 @@ HERE
     s.encoding.should == Encoding::US_ASCII
   end
 
+  it 'raises SyntaxError if quoted HEREDOC identifier is ending not on same line' do
+    -> {
+      eval %{<<"HERE\n"\nraises syntax error\nHERE}
+    }.should.raise(SyntaxError)
+  end
+
   it "allows HEREDOC with <<~'identifier', allowing to indent identifier and content" do
     require_relative 'fixtures/squiggly_heredoc'
     SquigglyHeredocSpecs.message.should == "character density, n.:\n  The number of very weird people in the office.\n"
@@ -84,8 +90,30 @@ HERE
     SquigglyHeredocSpecs.singlequoted.should == "singlequoted \#{\"interpolated\"}\n"
   end
 
+  it "allows HEREDOC with <<~'identifier', no interpolation, with backslash" do
+    require_relative 'fixtures/squiggly_heredoc'
+    SquigglyHeredocSpecs.backslash.should == "a\nbc\n"
+  end
+
   it "selects the least-indented line and removes its indentation from all the lines" do
     require_relative 'fixtures/squiggly_heredoc'
+    SquigglyHeredocSpecs.least_indented_on_the_first_line.should == "a\n  b\n    c\n"
     SquigglyHeredocSpecs.least_indented_on_the_last_line.should == "    a\n  b\nc\n"
   end
+
+  it "selects the least-indented line and removes its indentation from all the lines for <<~'identifier'" do
+    require_relative 'fixtures/squiggly_heredoc'
+    SquigglyHeredocSpecs.least_indented_on_the_first_line_single.should == "a\n  b\n    c\n"
+    SquigglyHeredocSpecs.least_indented_on_the_last_line_single.should == "    a\n  b\nc\n"
+  end
+
+  it "reports line numbers inside HEREDOC with method call" do
+    -> {
+      <<-HERE.chomp
+        a
+        b
+        #{c}
+      HERE
+    }.should.raise(NameError) { |e| e.backtrace[0].should.start_with?("#{__FILE__}:#{__LINE__ - 2}") }
+  end
 end
diff --git a/spec/ruby/language/if_spec.rb b/spec/ruby/language/if_spec.rb
index d1d95c1607..53fcb853d5 100644
--- a/spec/ruby/language/if_spec.rb
+++ b/spec/ruby/language/if_spec.rb
@@ -305,6 +305,59 @@ describe "The if expression" do
       6.times(&b)
       ScratchPad.recorded.should == [4, 5, 4, 5]
     end
+
+    it "warns when Integer literals are used instead of predicates" do
+      -> {
+        eval <<~RUBY
+          $. = 0
+          10.times { |i| ScratchPad << i if 4..5 }
+        RUBY
+      }.should complain(/warning: integer literal in flip-flop/, verbose: true)
+      ScratchPad.recorded.should == []
+    end
+  end
+
+  describe "when a branch syntactically does not return a value" do
+    it "raises SyntaxError if both do not return a value" do
+      -> {
+        eval <<~RUBY
+        def m
+          a = if rand
+            return
+          else
+            return
+          end
+          a
+        end
+        RUBY
+      }.should.raise(SyntaxError, /void value expression/)
+    end
+
+    it "does not raise SyntaxError if one branch returns a value" do
+      eval(<<~RUBY).should == 1
+      def m
+        a = if false # using false to make it clear that's not checked for
+          42
+        else
+          return 1
+        end
+        a
+      end
+      m
+      RUBY
+
+      eval(<<~RUBY).should == 1
+      def m
+        a = if true # using true to make it clear that's not checked for
+          return 1
+        else
+          42
+        end
+        a
+      end
+      m
+      RUBY
+    end
   end
 end
 
diff --git a/spec/ruby/language/it_parameter_spec.rb b/spec/ruby/language/it_parameter_spec.rb
new file mode 100644
index 0000000000..6ba67cbb4f
--- /dev/null
+++ b/spec/ruby/language/it_parameter_spec.rb
@@ -0,0 +1,108 @@
+require_relative '../spec_helper'
+
+ruby_version_is "3.4" do
+  eval <<-RUBY # use eval to avoid warnings on Ruby 3.3
+  describe "The `it` parameter" do
+    it "provides it in a block" do
+      -> { it }.call("a").should == "a"
+      proc { it }.call("a").should == "a"
+      lambda { it }.call("a").should == "a"
+      ["a"].map { it }.should == ["a"]
+    end
+
+    it "assigns nil to not passed parameters" do
+      proc { it }.call().should == nil
+    end
+
+    it "can be used in both outer and nested blocks at the same time" do
+      -> { it + -> { it * it }.call(2) }.call(3).should == 7
+    end
+
+    it "can be reassigned to act as a local variable" do
+      proc { tmp = it; it = tmp * 2; it }.call(21).should == 42
+    end
+
+    it "is a regular local variable if there is already a 'it' local variable" do
+      it = 0
+      proc { it }.call("a").should == 0
+    end
+
+    it "is a regular local variable if there is a method `it` defined" do
+      o = Object.new
+      def o.it
+        21
+      end
+
+      o.instance_eval("proc { it * 2 }").call(1).should == 2
+    end
+
+    it "is not shadowed by an reassignment in a block" do
+      a = nil
+      proc { a = it; it = 42 }.call(0)
+      a.should == 0 # if `it` were shadowed its value would be nil
+    end
+
+    it "raises SyntaxError when block parameters are specified explicitly" do
+      -> { eval("-> () { it }")         }.should.raise(SyntaxError, /ordinary parameter is defined/)
+      -> { eval("-> (x) { it }")        }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+      -> { eval("proc { || it }")       }.should.raise(SyntaxError, /ordinary parameter is defined/)
+      -> { eval("proc { |x| it }")      }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+      -> { eval("lambda { || it }")     }.should.raise(SyntaxError, /ordinary parameter is defined/)
+      -> { eval("lambda { |x| it }")    }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+      -> { eval("['a'].map { || it }")  }.should.raise(SyntaxError, /ordinary parameter is defined/)
+      -> { eval("['a'].map { |x| it }") }.should.raise(SyntaxError, /ordinary parameter is defined/)
+    end
+
+    it "cannot be mixed with numbered parameters" do
+      -> {
+        eval("proc { it + _1 }")
+      }.should.raise(SyntaxError, /numbered parameters are not allowed when 'it' is already used|'it' is already used in/)
+
+      -> {
+        eval("proc { _1 + it }")
+      }.should.raise(SyntaxError, /numbered parameter is already used in|'it' is not allowed when a numbered parameter is already used/)
+    end
+
+    it "affects block arity" do
+      -> {}.arity.should == 0
+      -> { it }.arity.should == 1
+    end
+
+    it "affects block parameters" do
+      -> { it }.parameters.should == [[:req]]
+
+      ruby_version_is ""..."4.0" do
+        proc { it }.parameters.should == [[:opt, nil]]
+      end
+      ruby_version_is "4.0" do
+        proc { it }.parameters.should == [[:opt]]
+      end
+    end
+
+    it "does not affect binding local variables" do
+      -> { it; binding.local_variables }.call("a").should == []
+    end
+
+    it "does not work in methods" do
+      obj = Object.new
+      def obj.foo; it; end
+
+      -> { obj.foo("a") }.should.raise(ArgumentError, /wrong number of arguments/)
+    end
+
+    context "given multiple arguments" do
+      it "provides it in a block and assigns the first argument for a block" do
+        proc { it }.call("a", "b").should == "a"
+      end
+
+      it "raises ArgumentError for a proc" do
+        -> { -> { it }.call("a", "b") }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 1)")
+        -> { lambda { it }.call("a", "b") }.should.raise(ArgumentError, "wrong number of arguments (given 2, expected 1)")
+      end
+    end
+  end
+  RUBY
+end
diff --git a/spec/ruby/language/keyword_arguments_spec.rb b/spec/ruby/language/keyword_arguments_spec.rb
new file mode 100644
index 0000000000..38edc24414
--- /dev/null
+++ b/spec/ruby/language/keyword_arguments_spec.rb
@@ -0,0 +1,398 @@
+require_relative '../spec_helper'
+
+describe "Keyword arguments" do
+  def target(*args, **kwargs)
+    [args, kwargs]
+  end
+
+  it "are separated from positional arguments" do
+    def m(*args, **kwargs)
+      [args, kwargs]
+    end
+
+    empty = {}
+    m(**empty).should == [[], {}]
+    m(empty).should == [[{}], {}]
+
+    m(a: 1).should == [[], {a: 1}]
+    m({a: 1}).should == [[{a: 1}], {}]
+  end
+
+  it "when the receiving method has not keyword parameters it treats kwargs as positional" do
+    def m(*a)
+      a
+    end
+
+    m(a: 1).should == [{a: 1}]
+    m({a: 1}).should == [{a: 1}]
+  end
+
+  context "empty kwargs are treated as if they were not passed" do
+    it "when calling a method" do
+      def m(*a)
+        a
+      end
+
+      empty = {}
+      m(**empty).should == []
+      m(empty).should == [{}]
+    end
+
+    it "when yielding to a block" do
+      def y(*args, **kwargs)
+        yield(*args, **kwargs)
+      end
+
+      empty = {}
+      y(**empty) { |*a| a }.should == []
+      y(empty) { |*a| a }.should == [{}]
+    end
+  end
+
+  it "extra keywords are not allowed without **kwrest" do
+    def m(*a, kw:)
+      a
+    end
+
+    m(kw: 1).should == []
+    -> { m(kw: 1, kw2: 2) }.should.raise(ArgumentError, 'unknown keyword: :kw2')
+    -> { m(kw: 1, true => false) }.should.raise(ArgumentError, 'unknown keyword: true')
+    -> { m(kw: 1, a: 1, b: 2, c: 3) }.should.raise(ArgumentError, 'unknown keywords: :a, :b, :c')
+  end
+
+  it "raises ArgumentError exception when required keyword argument is not passed" do
+    def m(a:, b:, c:)
+      [a, b, c]
+    end
+
+    -> { m(a: 1, b: 2) }.should.raise(ArgumentError, /missing keyword: :c/)
+    -> { m() }.should.raise(ArgumentError, /missing keywords: :a, :b, :c/)
+  end
+
+  it "raises ArgumentError for missing keyword arguments even if there are extra ones" do
+    def m(a:)
+      a
+    end
+
+    -> { m(b: 1) }.should.raise(ArgumentError, /missing keyword: :a/)
+  end
+
+  it "handle * and ** at the same call site" do
+    def m(*a)
+      a
+    end
+
+    m(*[], **{}).should == []
+    m(*[], 42, **{}).should == [42]
+  end
+
+  context "marked as ruby2_keywords_hash" do
+    it "is not copied when passed as a positional argument" do
+      h = Hash.ruby2_keywords_hash(a:1)
+
+      def bar(a)
+        a
+      end
+
+      h2 = bar(h)
+      h2.should.equal?(h)
+      Hash.ruby2_keywords_hash?(h).should == true
+    end
+  end
+
+  context "**" do
+    it "copies a non-empty Hash for a method taking (*args)" do
+      def m(*args)
+        args[0]
+      end
+
+      h = {a: 1}
+      m(**h).should_not.equal?(h)
+      h.should == {a: 1}
+    end
+
+    it "copies the given Hash for a method taking (**kwargs)" do
+      def m(**kw)
+        kw
+      end
+
+      empty = {}
+      m(**empty).should == empty
+      m(**empty).should_not.equal?(empty)
+
+      h = {a: 1}
+      m(**h).should == h
+      m(**h).should_not.equal?(h)
+    end
+  end
+
+  context "delegation" do
+    it "works with (*args, **kwargs)" do
+      def m(*args, **kwargs)
+        target(*args, **kwargs)
+      end
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      m(empty).should == [[{}], {}]
+
+      m(a: 1).should == [[], {a: 1}]
+      m({a: 1}).should == [[{a: 1}], {}]
+    end
+
+    it "works with proc { |*args, **kwargs| }" do
+      m = proc do |*args, **kwargs|
+        target(*args, **kwargs)
+      end
+
+      empty = {}
+      m.(**empty).should == [[], {}]
+      m.(empty).should == [[{}], {}]
+
+      m.(a: 1).should == [[], {a: 1}]
+      m.({a: 1}).should == [[{a: 1}], {}]
+
+      # no autosplatting for |*args, **kwargs|
+      m.([1, 2]).should == [[[1, 2]], {}]
+    end
+
+    it "works with -> (*args, **kwargs) {}" do
+      m = -> *args, **kwargs do
+        target(*args, **kwargs)
+      end
+
+      empty = {}
+      m.(**empty).should == [[], {}]
+      m.(empty).should == [[{}], {}]
+
+      m.(a: 1).should == [[], {a: 1}]
+      m.({a: 1}).should == [[{a: 1}], {}]
+    end
+
+    it "works with (...)" do
+      instance_eval <<~DEF
+      def m(...)
+        target(...)
+      end
+      DEF
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      m(empty).should == [[{}], {}]
+
+      m(a: 1).should == [[], {a: 1}]
+      m({a: 1}).should == [[{a: 1}], {}]
+    end
+
+    it "works with call(*ruby2_keyword_args)" do
+      class << self
+        ruby2_keywords def m(*args)
+          target(*args)
+        end
+      end
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+      m(empty).should == [[{}], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+
+      m(a: 1).should == [[], {a: 1}]
+      m({a: 1}).should == [[{a: 1}], {}]
+
+      kw = {a: 1}
+
+      m(**kw).should == [[], {a: 1}]
+      m(**kw)[1].should == kw
+      m(**kw)[1].should_not.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+      Hash.ruby2_keywords_hash?(m(**kw)[1]).should == false
+
+      m(kw).should == [[{a: 1}], {}]
+      m(kw)[0][0].should.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+    end
+
+    it "works with super(*ruby2_keyword_args)" do
+      parent = Class.new do
+        def m(*args, **kwargs)
+          [args, kwargs]
+        end
+      end
+
+      child = Class.new(parent) do
+        ruby2_keywords def m(*args)
+          super(*args)
+        end
+      end
+
+      obj = child.new
+
+      empty = {}
+      obj.m(**empty).should == [[], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+      obj.m(empty).should == [[{}], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+
+      obj.m(a: 1).should == [[], {a: 1}]
+      obj.m({a: 1}).should == [[{a: 1}], {}]
+
+      kw = {a: 1}
+
+      obj.m(**kw).should == [[], {a: 1}]
+      obj.m(**kw)[1].should == kw
+      obj.m(**kw)[1].should_not.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+      Hash.ruby2_keywords_hash?(obj.m(**kw)[1]).should == false
+
+      obj.m(kw).should == [[{a: 1}], {}]
+      obj.m(kw)[0][0].should.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+    end
+
+    it "works with zsuper" do
+      parent = Class.new do
+        def m(*args, **kwargs)
+          [args, kwargs]
+        end
+      end
+
+      child = Class.new(parent) do
+        ruby2_keywords def m(*args)
+          super
+        end
+      end
+
+      obj = child.new
+
+      empty = {}
+      obj.m(**empty).should == [[], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+      obj.m(empty).should == [[{}], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+
+      obj.m(a: 1).should == [[], {a: 1}]
+      obj.m({a: 1}).should == [[{a: 1}], {}]
+
+      kw = {a: 1}
+
+      obj.m(**kw).should == [[], {a: 1}]
+      obj.m(**kw)[1].should == kw
+      obj.m(**kw)[1].should_not.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+      Hash.ruby2_keywords_hash?(obj.m(**kw)[1]).should == false
+
+      obj.m(kw).should == [[{a: 1}], {}]
+      obj.m(kw)[0][0].should.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+    end
+
+    it "works with yield(*ruby2_keyword_args)" do
+      class << self
+        def y(args)
+          yield(*args)
+        end
+
+        ruby2_keywords def m(*outer_args)
+          y(outer_args, &-> *args, **kwargs { target(*args, **kwargs) })
+        end
+      end
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+      m(empty).should == [[{}], {}]
+      Hash.ruby2_keywords_hash?(empty).should == false
+
+      m(a: 1).should == [[], {a: 1}]
+      m({a: 1}).should == [[{a: 1}], {}]
+
+      kw = {a: 1}
+
+      m(**kw).should == [[], {a: 1}]
+      m(**kw)[1].should == kw
+      m(**kw)[1].should_not.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+      Hash.ruby2_keywords_hash?(m(**kw)[1]).should == false
+
+      m(kw).should == [[{a: 1}], {}]
+      m(kw)[0][0].should.equal?(kw)
+      Hash.ruby2_keywords_hash?(kw).should == false
+    end
+
+    it "does not work with (*args)" do
+      class << self
+        def m(*args)
+          target(*args)
+        end
+      end
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      m(empty).should == [[{}], {}]
+
+      m(a: 1).should == [[{a: 1}], {}]
+      m({a: 1}).should == [[{a: 1}], {}]
+    end
+
+    describe "omitted values" do
+      it "accepts short notation 'key' for 'key: value' syntax" do
+        def m(a:, b:)
+          [a, b]
+        end
+
+        a = 1
+        b = 2
+
+        m(a:, b:).should == [1, 2]
+      end
+    end
+
+    it "does not work with call(*ruby2_keyword_args) with missing ruby2_keywords in between" do
+      class << self
+        def n(*args) # Note the missing ruby2_keywords here
+          target(*args)
+        end
+
+        ruby2_keywords def m(*args)
+          n(*args)
+        end
+      end
+
+      empty = {}
+      m(**empty).should == [[], {}]
+      m(empty).should == [[{}], {}]
+
+      m(a: 1).should == [[{a: 1}], {}]
+      m({a: 1}).should == [[{a: 1}], {}]
+    end
+  end
+
+  context "in define_method(name, &proc)" do
+    # This tests that a free-standing proc used in define_method and converted to ruby2_keywords adopts that logic.
+    # See jruby/jruby#8119 for a case where aggressive JIT optimization broke later ruby2_keywords changes.
+    it "works with ruby2_keywords" do
+      m = Class.new do
+        def bar(a, foo: nil)
+          [a, foo]
+        end
+
+        # define_method and ruby2_keywords using send to avoid peephole optimizations
+        def self.setup
+          pr = make_proc
+          send :define_method, :foo, &pr
+          send :ruby2_keywords, :foo
+        end
+
+        # create proc in isolated method to force jit compilation on some implementations
+        def self.make_proc
+          proc { |a, *args| bar(a, *args) }
+        end
+      end
+
+      m.setup
+
+      m.new.foo(1, foo:2).should == [1, 2]
+    end
+  end
+end
diff --git a/spec/ruby/language/lambda_spec.rb b/spec/ruby/language/lambda_spec.rb
index 5fa7fa6bfa..c6239e32bb 100644
--- a/spec/ruby/language/lambda_spec.rb
+++ b/spec/ruby/language/lambda_spec.rb
@@ -11,25 +11,29 @@ describe "A lambda literal -> () { }" do
       end
     end
 
-    klass.new.create_lambda.should be_an_instance_of(Proc)
+    klass.new.create_lambda.should.instance_of?(Proc)
+  end
+
+  it "is not just syntactic sugar for Kernel#lambda" do
+    should_not_receive(:lambda)
+
+    -> {}
   end
 
   it "does not execute the block" do
-    -> { fail }.should be_an_instance_of(Proc)
+    -> { fail }.should.instance_of?(Proc)
   end
 
   it "returns a lambda" do
-    -> { }.lambda?.should be_true
+    -> { }.lambda?.should == true
   end
 
-  ruby_version_is "2.6" do
-    it "may include a rescue clause" do
-      eval('-> do raise ArgumentError; rescue ArgumentError; 7; end').should be_an_instance_of(Proc)
-    end
+  it "may include a rescue clause" do
+    eval('-> do raise ArgumentError; rescue ArgumentError; 7; end').should.instance_of?(Proc)
+  end
 
-    it "may include a ensure clause" do
-      eval('-> do 1; ensure; 2; end').should be_an_instance_of(Proc)
-    end
+  it "may include a ensure clause" do
+    eval('-> do 1; ensure; 2; end').should.instance_of?(Proc)
   end
 
   it "has its own scope for local variables" do
@@ -50,10 +54,10 @@ describe "A lambda literal -> () { }" do
         @d = -> do end
       ruby
 
-      @a.().should be_nil
-      @b.().should be_nil
-      @c.().should be_nil
-      @d.().should be_nil
+      @a.().should == nil
+      @b.().should == nil
+      @c.().should == nil
+      @d.().should == nil
     end
   end
 
@@ -93,9 +97,9 @@ describe "A lambda literal -> () { }" do
         @a = -> (*) { }
       ruby
 
-      @a.().should be_nil
-      @a.(1).should be_nil
-      @a.(1, 2, 3).should be_nil
+      @a.().should == nil
+      @a.(1).should == nil
+      @a.(1, 2, 3).should == nil
     end
 
     evaluate <<-ruby do
@@ -111,7 +115,7 @@ describe "A lambda literal -> () { }" do
         @a = -> (a:) { a }
       ruby
 
-      -> { @a.() }.should raise_error(ArgumentError)
+      -> { @a.() }.should.raise(ArgumentError)
       @a.(a: 1).should == 1
     end
 
@@ -127,9 +131,9 @@ describe "A lambda literal -> () { }" do
         @a = -> (**) {  }
       ruby
 
-      @a.().should be_nil
-      @a.(a: 1, b: 2).should be_nil
-      -> { @a.(1) }.should raise_error(ArgumentError)
+      @a.().should == nil
+      @a.(a: 1, b: 2).should == nil
+      -> { @a.(1) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -144,8 +148,8 @@ describe "A lambda literal -> () { }" do
         @a = -> (&b) { b  }
       ruby
 
-      @a.().should be_nil
-      @a.() { }.should be_an_instance_of(Proc)
+      @a.().should == nil
+      @a.() { }.should.instance_of?(Proc)
     end
 
     evaluate <<-ruby do
@@ -153,8 +157,8 @@ describe "A lambda literal -> () { }" do
       ruby
 
       @a.(1, 2).should == [1, 2]
-      -> { @a.() }.should raise_error(ArgumentError)
-      -> { @a.(1) }.should raise_error(ArgumentError)
+      -> { @a.() }.should.raise(ArgumentError)
+      -> { @a.(1) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -186,20 +190,18 @@ describe "A lambda literal -> () { }" do
       @a.().should == {}
       @a.(1, 2, 3, a: 4, b: 5).should == {a: 4, b: 5}
 
-      suppress_keyword_warning do
-        h = mock("keyword splat")
-        h.should_receive(:to_hash).and_return({a: 1})
-        @a.(h).should == {a: 1}
-      end
+      h = mock("keyword splat")
+      h.should_not_receive(:to_hash)
+      @a.(h).should == {}
     end
 
     evaluate <<-ruby do
         @a = -> (*, &b) { b }
       ruby
 
-      @a.().should be_nil
-      @a.(1, 2, 3, 4).should be_nil
-      @a.(&(l = ->{})).should equal(l)
+      @a.().should == nil
+      @a.(1, 2, 3, 4).should == nil
+      @a.(&(l = ->{})).should.equal?(l)
     end
 
     evaluate <<-ruby do
@@ -267,20 +269,21 @@ describe "A lambda literal -> () { }" do
     end
 
     describe "with circular optional argument reference" do
-      it "shadows an existing local with the same name as the argument" do
-        a = 1
-        -> {
-          @proc = eval "-> (a=a) { a }"
-        }.should complain(/circular argument reference/)
-        @proc.call.should == nil
+      ruby_version_is ""..."3.4" do
+        it "raises a SyntaxError if using the argument in its default value" do
+          a = 1
+          -> {
+            eval "-> (a=a) { a }"
+          }.should.raise(SyntaxError)
+        end
       end
 
-      it "shadows an existing method with the same name as the argument" do
-        def a; 1; end
-        -> {
-          @proc = eval "-> (a=a) { a }"
-        }.should complain(/circular argument reference/)
-        @proc.call.should == nil
+      ruby_version_is "3.4" do
+        it "is nil if using the argument in its default value" do
+          -> {
+            eval "-> (a=a) { a }.call"
+          }.call.should == nil
+        end
       end
 
       it "calls an existing method with the same name as the argument if explicitly using ()" do
@@ -289,6 +292,24 @@ describe "A lambda literal -> () { }" do
       end
     end
   end
+
+  evaluate <<-ruby do
+    @a = -> (**nil) { :ok }
+    ruby
+
+    @a.call().should == :ok
+    -> { @a.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    -> { @a.call(**{a: 1}) }.should.raise(ArgumentError, 'no keywords accepted')
+    -> { @a.call("a" => 1) }.should.raise(ArgumentError, 'no keywords accepted')
+  end
+
+  evaluate <<-ruby do
+    @a = -> (a, **nil) { a }
+    ruby
+
+    @a.call({a: 1}).should == {a: 1}
+    -> { @a.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+  end
 end
 
 describe "A lambda expression 'lambda { ... }'" do
@@ -302,51 +323,38 @@ describe "A lambda expression 'lambda { ... }'" do
       lambda { }
     end
 
-    obj.define.should equal(obj)
+    obj.define.should.equal?(obj)
   end
 
   it "does not execute the block" do
-    lambda { fail }.should be_an_instance_of(Proc)
+    lambda { fail }.should.instance_of?(Proc)
   end
 
   it "returns a lambda" do
-    lambda { }.lambda?.should be_true
+    lambda { }.lambda?.should == true
   end
 
   it "requires a block" do
-    lambda { lambda }.should raise_error(ArgumentError)
-  end
-
-  ruby_version_is "2.5" do
-    it "may include a rescue clause" do
-      eval('lambda do raise ArgumentError; rescue ArgumentError; 7; end').should be_an_instance_of(Proc)
+    suppress_warning do
+      lambda { lambda }.should.raise(ArgumentError)
     end
   end
 
+  it "may include a rescue clause" do
+    eval('lambda do raise ArgumentError; rescue ArgumentError; 7; end').should.instance_of?(Proc)
+  end
 
   context "with an implicit block" do
     before do
       def meth; lambda; end
     end
 
-    ruby_version_is ""..."2.7" do
-      it "can be created" do
-        implicit_lambda = nil
-        -> {
-          implicit_lambda = meth { 1 }
-        }.should complain(/tried to create Proc object without a block/)
-
-        implicit_lambda.lambda?.should be_true
-        implicit_lambda.call.should == 1
-      end
-    end
-
-    ruby_version_is "2.7" do
-      it "raises ArgumentError" do
-        implicit_lambda = nil
+    it "raises ArgumentError" do
+      implicit_lambda = nil
+      suppress_warning do
         -> {
           meth { 1 }
-        }.should raise_error(ArgumentError, /tried to create Proc object without a block/)
+        }.should.raise(ArgumentError, /tried to create Proc object without a block/)
       end
     end
   end
@@ -357,8 +365,8 @@ describe "A lambda expression 'lambda { ... }'" do
         @b = lambda { || }
       ruby
 
-      @a.().should be_nil
-      @b.().should be_nil
+      @a.().should == nil
+      @b.().should == nil
     end
   end
 
@@ -375,8 +383,8 @@ describe "A lambda expression 'lambda { ... }'" do
         @a = lambda { |a| a }
       ruby
 
-      lambda { m(&@a) }.should raise_error(ArgumentError)
-      lambda { m(1, 2, &@a) }.should raise_error(ArgumentError)
+      lambda { m(&@a) }.should.raise(ArgumentError)
+      lambda { m(1, 2, &@a) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -386,8 +394,8 @@ describe "A lambda expression 'lambda { ... }'" do
       @a.(1).should == 1
       @a.([1, 2]).should == [1, 2]
 
-      lambda { @a.() }.should raise_error(ArgumentError)
-      lambda { @a.(1, 2) }.should raise_error(ArgumentError)
+      lambda { @a.() }.should.raise(ArgumentError)
+      lambda { @a.(1, 2) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -400,7 +408,7 @@ describe "A lambda expression 'lambda { ... }'" do
       m(1, &@a).should == 1
       m([1, 2], &@a).should == [1, 2]
 
-      lambda { m2(&@a) }.should raise_error(ArgumentError)
+      lambda { m2(&@a) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -431,9 +439,9 @@ describe "A lambda expression 'lambda { ... }'" do
         @a = lambda { |*| }
       ruby
 
-      @a.().should be_nil
-      @a.(1).should be_nil
-      @a.(1, 2, 3).should be_nil
+      @a.().should == nil
+      @a.(1).should == nil
+      @a.(1, 2, 3).should == nil
     end
 
     evaluate <<-ruby do
@@ -449,7 +457,7 @@ describe "A lambda expression 'lambda { ... }'" do
         @a = lambda { |a:| a }
       ruby
 
-      lambda { @a.() }.should raise_error(ArgumentError)
+      lambda { @a.() }.should.raise(ArgumentError)
       @a.(a: 1).should == 1
     end
 
@@ -465,9 +473,9 @@ describe "A lambda expression 'lambda { ... }'" do
         @a = lambda { |**|  }
       ruby
 
-      @a.().should be_nil
-      @a.(a: 1, b: 2).should be_nil
-      lambda { @a.(1) }.should raise_error(ArgumentError)
+      @a.().should == nil
+      @a.(a: 1, b: 2).should == nil
+      lambda { @a.(1) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -482,8 +490,8 @@ describe "A lambda expression 'lambda { ... }'" do
         @a = lambda { |&b| b  }
       ruby
 
-      @a.().should be_nil
-      @a.() { }.should be_an_instance_of(Proc)
+      @a.().should == nil
+      @a.() { }.should.instance_of?(Proc)
     end
 
     evaluate <<-ruby do
@@ -522,20 +530,18 @@ describe "A lambda expression 'lambda { ... }'" do
       @a.().should == {}
       @a.(1, 2, 3, a: 4, b: 5).should == {a: 4, b: 5}
 
-      suppress_keyword_warning do
-        h = mock("keyword splat")
-        h.should_receive(:to_hash).and_return({a: 1})
-        @a.(h).should == {a: 1}
-      end
+      h = mock("keyword splat")
+      h.should_not_receive(:to_hash)
+      @a.(h).should == {}
     end
 
     evaluate <<-ruby do
         @a = lambda { |*, &b| b }
       ruby
 
-      @a.().should be_nil
-      @a.(1, 2, 3, 4).should be_nil
-      @a.(&(l = ->{})).should equal(l)
+      @a.().should == nil
+      @a.(1, 2, 3, 4).should == nil
+      @a.(&(l = ->{})).should.equal?(l)
     end
 
     evaluate <<-ruby do
@@ -601,5 +607,23 @@ describe "A lambda expression 'lambda { ... }'" do
       result = @a.(1, 2, e: 3, g: 4, h: 5, i: 6, &(l = ->{}))
       result.should == [1, 1, [], 2, 3, 2, 4, { h: 5, i: 6 }, l]
     end
+
+    evaluate <<-ruby do
+      @a = lambda { |**nil| :ok }
+      ruby
+
+      @a.call().should == :ok
+      -> { @a.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { @a.call(**{a: 1}) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { @a.call("a" => 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    end
+
+    evaluate <<-ruby do
+      @a = lambda { |a, **nil| a }
+      ruby
+
+      @a.call({a: 1}).should == {a: 1}
+      -> { @a.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    end
   end
 end
diff --git a/spec/ruby/language/line_spec.rb b/spec/ruby/language/line_spec.rb
index fcadaa71d7..2864798079 100644
--- a/spec/ruby/language/line_spec.rb
+++ b/spec/ruby/language/line_spec.rb
@@ -4,7 +4,7 @@ require_relative 'shared/__LINE__'
 
 describe "The __LINE__ pseudo-variable" do
   it "raises a SyntaxError if assigned to" do
-    -> { eval("__LINE__ = 1") }.should raise_error(SyntaxError)
+    -> { eval("__LINE__ = 1") }.should.raise(SyntaxError)
   end
 
   before :each do
diff --git a/spec/ruby/language/loop_spec.rb b/spec/ruby/language/loop_spec.rb
index fd17b53910..9b12765a5f 100644
--- a/spec/ruby/language/loop_spec.rb
+++ b/spec/ruby/language/loop_spec.rb
@@ -15,7 +15,7 @@ describe "The loop expression" do
       inner_loop = 123
       break
     end
-    -> { inner_loop }.should raise_error(NameError)
+    -> { inner_loop }.should.raise(NameError)
   end
 
   it "returns the value passed to break if interrupted by break" do
diff --git a/spec/ruby/language/magic_comment_spec.rb b/spec/ruby/language/magic_comment_spec.rb
index f2bf3a08e5..af9c9dbfd0 100644
--- a/spec/ruby/language/magic_comment_spec.rb
+++ b/spec/ruby/language/magic_comment_spec.rb
@@ -45,7 +45,8 @@ end
 
 describe "Magic comments" do
   describe "in stdin" do
-    it_behaves_like :magic_comments, :locale, -> file {
+    default = (platform_is :windows and ruby_version_is "4.0") ? :UTF8 : :locale
+    it_behaves_like :magic_comments, default, -> file {
       print_at_exit = fixture(__FILE__, "print_magic_comment_result_at_exit.rb")
       ruby_exe(nil, args: "< #{fixture(__FILE__, file)}", options: "-r#{print_at_exit}")
     }
diff --git a/spec/ruby/language/match_spec.rb b/spec/ruby/language/match_spec.rb
index 36d347bd57..096ebee022 100644
--- a/spec/ruby/language/match_spec.rb
+++ b/spec/ruby/language/match_spec.rb
@@ -46,6 +46,21 @@ describe "The =~ operator with named captures" do
       matched.should == "foo"
       unmatched.should == nil
     end
+
+    it "sets existing local variables if declared in a higher scope" do
+      a = 42
+      1.times do
+        /(?<a>foo)/ =~ @string
+      end
+      a.should == "foo"
+    end
+  end
+
+  describe "on syntax of 'string_literal' =~ /regexp/" do
+    it "does not set local variables" do
+      'string literal' =~ /(?<matched>str)(?<unmatched>lit)?/
+      local_variables.should == []
+    end
   end
 
   describe "on syntax of string_variable =~ /regexp/" do
diff --git a/spec/ruby/language/metaclass_spec.rb b/spec/ruby/language/metaclass_spec.rb
index fc83067977..3bee823a75 100644
--- a/spec/ruby/language/metaclass_spec.rb
+++ b/spec/ruby/language/metaclass_spec.rb
@@ -16,17 +16,17 @@ describe "self in a metaclass body (class << obj)" do
   end
 
   it "raises a TypeError for numbers" do
-    -> { class << 1; self; end }.should raise_error(TypeError)
+    -> { class << 1; self; end }.should.raise(TypeError)
   end
 
   it "raises a TypeError for symbols" do
-    -> { class << :symbol; self; end }.should raise_error(TypeError)
+    -> { class << :symbol; self; end }.should.raise(TypeError)
   end
 
   it "is a singleton Class instance" do
     cls = class << mock('x'); self; end
     cls.is_a?(Class).should == true
-    cls.should_not equal(Object)
+    cls.should_not.equal?(Object)
   end
 end
 
@@ -57,20 +57,20 @@ describe "A constant on a metaclass" do
   end
 
   it "is not defined on the object's class" do
-    @object.class.const_defined?(:CONST).should be_false
+    @object.class.const_defined?(:CONST).should == false
   end
 
   it "is not defined in the metaclass opener's scope" do
     class << @object
       CONST
     end
-    -> { CONST }.should raise_error(NameError)
+    -> { CONST }.should.raise(NameError)
   end
 
   it "cannot be accessed via object::CONST" do
     -> do
       @object::CONST
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a NameError for anonymous_module::CONST" do
@@ -81,16 +81,16 @@ describe "A constant on a metaclass" do
 
     -> do
       @object::CONST
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "appears in the metaclass constant list" do
     constants = class << @object; constants; end
-    constants.should include(:CONST)
+    constants.should.include?(:CONST)
   end
 
   it "does not appear in the object's class constant list" do
-    @object.class.constants.should_not include(:CONST)
+    @object.class.constants.should_not.include?(:CONST)
   end
 
   it "is not preserved when the object is duped" do
@@ -98,14 +98,14 @@ describe "A constant on a metaclass" do
 
     -> do
       class << @object; CONST; end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "is preserved when the object is cloned" do
     @object = @object.clone
 
     class << @object
-      CONST.should_not be_nil
+      CONST.should_not == nil
     end
   end
 end
diff --git a/spec/ruby/language/method_spec.rb b/spec/ruby/language/method_spec.rb
index 0486025792..324bd6cea5 100644
--- a/spec/ruby/language/method_spec.rb
+++ b/spec/ruby/language/method_spec.rb
@@ -19,7 +19,7 @@ describe "A method send" do
       x = mock("splat argument")
       x.should_not_receive(:to_ary)
 
-      m(*x).should equal(x)
+      m(*x).should.equal?(x)
     end
 
     it "calls #to_a" do
@@ -40,7 +40,7 @@ describe "A method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { m(*x) }.should raise_error(TypeError)
+      -> { m(*x) }.should.raise(TypeError)
     end
   end
 
@@ -74,7 +74,7 @@ describe "A method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { m(*x, 2, 3) }.should raise_error(TypeError)
+      -> { m(*x, 2, 3) }.should.raise(TypeError)
     end
   end
 
@@ -108,13 +108,13 @@ describe "A method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { m(1, *x, 2, 3) }.should raise_error(TypeError)
+      -> { m(1, *x, 2, 3) }.should.raise(TypeError)
     end
 
     it "copies the splatted array" do
       args = [3, 4]
       m(1, 2, *args, 4, 5).should == [1, 2, [3, 4], 4, 5]
-      m(1, 2, *args, 4, 5)[2].should_not equal(args)
+      m(1, 2, *args, 4, 5)[2].should_not.equal?(args)
     end
 
     it "allows an array being splatted to be modified by another argument" do
@@ -153,7 +153,27 @@ describe "A method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { m(1, 2, *x) }.should raise_error(TypeError)
+      -> { m(1, 2, *x) }.should.raise(TypeError)
+    end
+  end
+
+  context "with a block argument" do
+    before :all do
+      def m(x)
+        if block_given?
+          [true, yield(x + 'b')]
+        else
+          [false]
+        end
+      end
+    end
+
+    it "that refers to a proc passes the proc as the block" do
+      m('a', &-> y { y + 'c'}).should == [true, 'abc']
+    end
+
+    it "that is nil passes no block" do
+      m('a', &nil).should == [false]
     end
   end
 end
@@ -197,7 +217,7 @@ describe "An element assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o[*x] = 1 }.should raise_error(TypeError)
+      -> { @o[*x] = 1 }.should.raise(TypeError)
     end
   end
 
@@ -235,7 +255,7 @@ describe "An element assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o[*x, 2, 3] = 4 }.should raise_error(TypeError)
+      -> { @o[*x, 2, 3] = 4 }.should.raise(TypeError)
     end
   end
 
@@ -273,7 +293,7 @@ describe "An element assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o[1, 2, *x, 3] = 4 }.should raise_error(TypeError)
+      -> { @o[1, 2, *x, 3] = 4 }.should.raise(TypeError)
     end
   end
 
@@ -311,7 +331,7 @@ describe "An element assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o[1, 2, 3, *x] = 4 }.should raise_error(TypeError)
+      -> { @o[1, 2, 3, *x] = 4 }.should.raise(TypeError)
     end
   end
 end
@@ -348,7 +368,7 @@ describe "An attribute assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o.send :m=, *x, 1 }.should raise_error(TypeError)
+      -> { @o.send :m=, *x, 1 }.should.raise(TypeError)
     end
   end
 
@@ -383,7 +403,7 @@ describe "An attribute assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o.send :m=, *x, 2, 3, 4 }.should raise_error(TypeError)
+      -> { @o.send :m=, *x, 2, 3, 4 }.should.raise(TypeError)
     end
   end
 
@@ -418,7 +438,7 @@ describe "An attribute assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o.send :m=, 1, 2, *x, 3, 4 }.should raise_error(TypeError)
+      -> { @o.send :m=, 1, 2, *x, 3, 4 }.should.raise(TypeError)
     end
   end
 
@@ -453,7 +473,7 @@ describe "An attribute assignment method send" do
       x = mock("splat argument")
       x.should_receive(:to_a).and_return(1)
 
-      -> { @o.send :m=, 1, 2, 3, *x, 4 }.should raise_error(TypeError)
+      -> { @o.send :m=, 1, 2, 3, *x, 4 }.should.raise(TypeError)
     end
   end
 end
@@ -467,7 +487,7 @@ describe "A method" do
         end
       ruby
 
-      m.should be_nil
+      m.should == nil
     end
 
     evaluate <<-ruby do
@@ -475,7 +495,7 @@ describe "A method" do
         end
       ruby
 
-      m.should be_nil
+      m.should == nil
     end
   end
 
@@ -484,7 +504,7 @@ describe "A method" do
         def m(a) a end
       ruby
 
-      m((args = 1, 2, 3)).should equal(args)
+      m((args = 1, 2, 3)).should.equal?(args)
     end
 
     evaluate <<-ruby do
@@ -515,18 +535,18 @@ describe "A method" do
         def m() end
       ruby
 
-      m().should be_nil
-      m(*[]).should be_nil
-      m(**{}).should be_nil
+      m().should == nil
+      m(*[]).should == nil
+      m(**{}).should == nil
     end
 
     evaluate <<-ruby do
         def m(*) end
       ruby
 
-      m().should be_nil
-      m(1).should be_nil
-      m(1, 2, 3).should be_nil
+      m().should == nil
+      m(1).should == nil
+      m(1, 2, 3).should == nil
     end
 
     evaluate <<-ruby do
@@ -544,14 +564,21 @@ describe "A method" do
         def m(a:) a end
       ruby
 
-      -> { m() }.should raise_error(ArgumentError)
+      -> { m() }.should.raise(ArgumentError)
       m(a: 1).should == 1
       suppress_keyword_warning do
-        -> { m("a" => 1, a: 1) }.should raise_error(ArgumentError)
+        -> { m("a" => 1, a: 1) }.should.raise(ArgumentError)
       end
     end
 
     evaluate <<-ruby do
+        def m(a:, **kw) [a, kw] end
+      ruby
+
+      -> { m(b: 1) }.should.raise(ArgumentError)
+    end
+
+    evaluate <<-ruby do
         def m(a: 1) a end
       ruby
 
@@ -563,9 +590,9 @@ describe "A method" do
         def m(**) end
       ruby
 
-      m().should be_nil
-      m(a: 1, b: 2).should be_nil
-      -> { m(1) }.should raise_error(ArgumentError)
+      m().should == nil
+      m(a: 1, b: 2).should == nil
+      -> { m(1) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -576,15 +603,24 @@ describe "A method" do
       m(a: 1, b: 2).should == { a: 1, b: 2 }
       m(*[]).should == {}
       m(**{}).should == {}
-      m(**{a: 1, b: 2}, **{a: 4, c: 7}).should == { a: 4, b: 2, c: 7 }
-      -> { m(2) }.should raise_error(ArgumentError)
+      suppress_warning {
+        eval "m(**{a: 1, b: 2}, **{a: 4, c: 7})"
+      }.should == { a: 4, b: 2, c: 7 }
+      -> { m(2) }.should.raise(ArgumentError)
+    end
+
+    evaluate <<-ruby do
+      def m(**k); k end;
+      ruby
+
+      m("a" => 1).should == { "a" => 1 }
     end
 
     evaluate <<-ruby do
         def m(&b) b end
       ruby
 
-      m { }.should be_an_instance_of(Proc)
+      m { }.should.instance_of?(Proc)
     end
 
     evaluate <<-ruby do
@@ -614,9 +650,9 @@ describe "A method" do
         def m((*), (*)) end
       ruby
 
-      m(2, 3).should be_nil
-      m([2, 3, 4], [5, 6]).should be_nil
-      -> { m a: 1 }.should raise_error(ArgumentError)
+      m(2, 3).should == nil
+      m([2, 3, 4], [5, 6]).should == nil
+      -> { m a: 1 }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -709,7 +745,7 @@ describe "A method" do
 
       m(1, b: 2).should == [1, 2]
       suppress_keyword_warning do
-        -> { m("a" => 1, b: 2) }.should raise_error(ArgumentError)
+        -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
       end
     end
 
@@ -719,9 +755,7 @@ describe "A method" do
 
       m(2).should == [2, 1]
       m(1, b: 2).should == [1, 2]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [{"a" => 1, b: 2}, 1]
-      end
+      -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -730,9 +764,7 @@ describe "A method" do
 
       m(1).should == 1
       m(1, a: 2, b: 3).should == 1
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == {"a" => 1, b: 2}
-      end
+      -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -741,9 +773,7 @@ describe "A method" do
 
       m(1).should == [1, {}]
       m(1, a: 2, b: 3).should == [1, {a: 2, b: 3}]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [{"a" => 1, b: 2}, {}]
-      end
+      -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -818,8 +848,8 @@ describe "A method" do
         def m(a=1, (*b), (*c)) [a, b, c] end
       ruby
 
-      -> { m() }.should raise_error(ArgumentError)
-      -> { m(2) }.should raise_error(ArgumentError)
+      -> { m() }.should.raise(ArgumentError)
+      -> { m(2) }.should.raise(ArgumentError)
       m(2, 3).should == [1, [2], [3]]
       m(2, [3, 4], [5, 6]).should == [2, [3, 4], [5, 6]]
     end
@@ -860,9 +890,7 @@ describe "A method" do
 
       m(b: 2).should == [1, 2]
       m(2, b: 1).should == [2, 1]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [{"a" => 1}, 2]
-      end
+      -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
     end
 
     evaluate <<-ruby do
@@ -872,31 +900,16 @@ describe "A method" do
       m().should == [1, 2]
       m(2).should == [2, 2]
       m(b: 3).should == [1, 3]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [{"a" => 1}, 2]
-      end
-    end
-
-    ruby_version_is ""..."2.7" do
-      evaluate <<-ruby do
-          def m(a=1, **) a end
-        ruby
-
-        m().should == 1
-        m(2, a: 1, b: 0).should == 2
-        m("a" => 1, a: 2).should == {"a" => 1}
-      end
+      -> { m("a" => 1, b: 2) }.should.raise(ArgumentError)
     end
 
-    ruby_version_is "2.7" do
-      evaluate <<-ruby do
-          def m(a=1, **) a end
-        ruby
+    evaluate <<-ruby do
+        def m(a=1, **) a end
+      ruby
 
-        m().should == 1
-        m(2, a: 1, b: 0).should == 2
-        m("a" => 1, a: 2).should == 1
-      end
+      m().should == 1
+      m(2, a: 1, b: 0).should == 2
+      m("a" => 1, a: 2).should == 1
     end
 
     evaluate <<-ruby do
@@ -937,262 +950,12 @@ describe "A method" do
     end
 
     evaluate <<-ruby do
-        def m(*, a:) a end
-      ruby
-
-      m(a: 1).should == 1
-      m(1, 2, a: 3).should == 3
-      suppress_keyword_warning do
-        m("a" => 1, a: 2).should == 2
-      end
-    end
-
-    evaluate <<-ruby do
-        def m(*a, b:) [a, b] end
-      ruby
-
-      m(b: 1).should == [[], 1]
-      m(1, 2, b: 3).should == [[1, 2], 3]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [[{"a" => 1}], 2]
-      end
-    end
-
-    evaluate <<-ruby do
-        def m(*, a: 1) a end
-      ruby
-
-      m().should == 1
-      m(1, 2).should == 1
-      m(a: 2).should == 2
-      m(1, a: 2).should == 2
-      suppress_keyword_warning do
-        m("a" => 1, a: 2).should == 2
-      end
-    end
-
-    evaluate <<-ruby do
-        def m(*a, b: 1) [a, b] end
-      ruby
-
-      m().should == [[], 1]
-      m(1, 2, 3, b: 4).should == [[1, 2, 3], 4]
-      suppress_keyword_warning do
-        m("a" => 1, b: 2).should == [[{"a" => 1}], 2]
-      end
-
-      a = mock("splat")
-      a.should_not_receive(:to_ary)
-      m(*a).should == [[a], 1]
-    end
-
-    evaluate <<-ruby do
-        def m(*, **) end
-      ruby
-
-      m().should be_nil
-      m(a: 1, b: 2).should be_nil
-      m(1, 2, 3, a: 4, b: 5).should be_nil
-
-      h = mock("keyword splat")
-      h.should_receive(:to_hash).and_return({a: 1})
-      suppress_keyword_warning do
-        m(h).should be_nil
-      end
-
-      h = mock("keyword splat")
-      error = RuntimeError.new("error while converting to a hash")
-      h.should_receive(:to_hash).and_raise(error)
-      -> { m(h) }.should raise_error(error)
-    end
-
-    ruby_version_is ""..."2.7" do
-      evaluate <<-ruby do
-          def m(*a, **) a end
-        ruby
-
-        m().should == []
-        m(1, 2, 3, a: 4, b: 5).should == [1, 2, 3]
-        m("a" => 1, a: 1).should == [{"a" => 1}]
-        m(1, **{a: 2}).should == [1]
-
-        h = mock("keyword splat")
-        h.should_receive(:to_hash)
-        -> { m(**h) }.should raise_error(TypeError)
-      end
-
-      evaluate <<-ruby do
-          def m(*, **k) k end
-        ruby
-
-        m().should == {}
-        m(1, 2, 3, a: 4, b: 5).should == {a: 4, b: 5}
-        m("a" => 1, a: 1).should == {a: 1}
-
-        h = mock("keyword splat")
-        h.should_receive(:to_hash).and_return({a: 1})
-        m(h).should == {a: 1}
-      end
-
-      evaluate <<-ruby do
-          def m(a = nil, **k) [a, k] end
-        ruby
-
-        m().should == [nil, {}]
-        m("a" => 1).should == [{"a" => 1}, {}]
-        m(a: 1).should == [nil, {a: 1}]
-        m("a" => 1, a: 1).should == [{"a" => 1}, {a: 1}]
-        m({ "a" => 1 }, a: 1).should == [{"a" => 1}, {a: 1}]
-        m({a: 1}, {}).should == [{a: 1}, {}]
-
-        h = {"a" => 1, b: 2}
-        m(h).should == [{"a" => 1}, {b: 2}]
-        h.should == {"a" => 1, b: 2}
-
-        h = {"a" => 1}
-        m(h).first.should == h
-
-        h = {}
-        r = m(h)
-        r.first.should be_nil
-        r.last.should == {}
-
-        hh = {}
-        h = mock("keyword splat empty hash")
-        h.should_receive(:to_hash).and_return(hh)
-        r = m(h)
-        r.first.should be_nil
-        r.last.should == {}
-
-        h = mock("keyword splat")
-        h.should_receive(:to_hash).and_return({"a" => 1, a: 2})
-        m(h).should == [{"a" => 1}, {a: 2}]
-      end
-
-      evaluate <<-ruby do
-          def m(*a, **k) [a, k] end
-        ruby
-
-        m().should == [[], {}]
-        m(1).should == [[1], {}]
-        m(a: 1, b: 2).should == [[], {a: 1, b: 2}]
-        m(1, 2, 3, a: 2).should == [[1, 2, 3], {a: 2}]
-
-        m("a" => 1).should == [[{"a" => 1}], {}]
-        m(a: 1).should == [[], {a: 1}]
-        m("a" => 1, a: 1).should == [[{"a" => 1}], {a: 1}]
-        m({ "a" => 1 }, a: 1).should == [[{"a" => 1}], {a: 1}]
-        m({a: 1}, {}).should == [[{a: 1}], {}]
-        m({a: 1}, {"a" => 1}).should == [[{a: 1}, {"a" => 1}], {}]
-
-        bo = BasicObject.new
-        def bo.to_a; [1, 2, 3]; end
-        def bo.to_hash; {:b => 2, :c => 3}; end
-
-        m(*bo, **bo).should == [[1, 2, 3], {:b => 2, :c => 3}]
-      end
-    end
-
-    ruby_version_is "2.7" do
-      evaluate <<-ruby do
-          def m(*a, **) a end
-        ruby
-
-        m().should == []
-        m(1, 2, 3, a: 4, b: 5).should == [1, 2, 3]
-        m("a" => 1, a: 1).should == []
-        m(1, **{a: 2}).should == [1]
-
-        h = mock("keyword splat")
-        h.should_receive(:to_hash)
-        -> { m(**h) }.should raise_error(TypeError)
-      end
-
-      evaluate <<-ruby do
-          def m(*, **k) k end
-        ruby
-
-        m().should == {}
-        m(1, 2, 3, a: 4, b: 5).should == {a: 4, b: 5}
-        m("a" => 1, a: 1).should == {"a" => 1, a: 1}
-
-        h = mock("keyword splat")
-        h.should_receive(:to_hash).and_return({a: 1})
-        suppress_warning do
-          m(h).should == {a: 1}
-        end
-      end
-
-      evaluate <<-ruby do
-          def m(a = nil, **k) [a, k] end
-        ruby
-
-        m().should == [nil, {}]
-        m("a" => 1).should == [nil, {"a" => 1}]
-        m(a: 1).should == [nil, {a: 1}]
-        m("a" => 1, a: 1).should == [nil, {"a" => 1, a: 1}]
-        m({ "a" => 1 }, a: 1).should == [{"a" => 1}, {a: 1}]
-        suppress_warning do
-          m({a: 1}, {}).should == [{a: 1}, {}]
-
-          h = {"a" => 1, b: 2}
-          m(h).should == [{"a" => 1}, {b: 2}]
-          h.should == {"a" => 1, b: 2}
-
-          h = {"a" => 1}
-          m(h).first.should == h
-
-          h = {}
-          r = m(h)
-          r.first.should be_nil
-          r.last.should == {}
-
-          hh = {}
-          h = mock("keyword splat empty hash")
-          h.should_receive(:to_hash).and_return(hh)
-          r = m(h)
-          r.first.should be_nil
-          r.last.should == {}
-
-          h = mock("keyword splat")
-          h.should_receive(:to_hash).and_return({"a" => 1, a: 2})
-          m(h).should == [{"a" => 1}, {a: 2}]
-        end
-      end
-
-      evaluate <<-ruby do
-          def m(*a, **k) [a, k] end
-        ruby
-
-        m().should == [[], {}]
-        m(1).should == [[1], {}]
-        m(a: 1, b: 2).should == [[], {a: 1, b: 2}]
-        m(1, 2, 3, a: 2).should == [[1, 2, 3], {a: 2}]
-
-        m("a" => 1).should == [[], {"a" => 1}]
-        m(a: 1).should == [[], {a: 1}]
-        m("a" => 1, a: 1).should == [[], {"a" => 1, a: 1}]
-        m({ "a" => 1 }, a: 1).should == [[{"a" => 1}], {a: 1}]
-        suppress_warning do
-          m({a: 1}, {}).should == [[{a: 1}], {}]
-        end
-        m({a: 1}, {"a" => 1}).should == [[{a: 1}, {"a" => 1}], {}]
-
-        bo = BasicObject.new
-        def bo.to_a; [1, 2, 3]; end
-        def bo.to_hash; {:b => 2, :c => 3}; end
-
-        m(*bo, **bo).should == [[1, 2, 3], {:b => 2, :c => 3}]
-      end
-    end
-
-    evaluate <<-ruby do
         def m(*, &b) b end
       ruby
 
-      m().should be_nil
-      m(1, 2, 3, 4).should be_nil
-      m(&(l = ->{})).should equal(l)
+      m().should == nil
+      m(1, 2, 3, 4).should == nil
+      m(&(l = ->{})).should.equal?(l)
     end
 
     evaluate <<-ruby do
@@ -1210,7 +973,7 @@ describe "A method" do
 
       m(a: 1, b: 2).should == [1, 2]
       suppress_keyword_warning do
-        -> { m("a" => 1, a: 1, b: 2) }.should raise_error(ArgumentError)
+        -> { m("a" => 1, a: 1, b: 2) }.should.raise(ArgumentError)
       end
     end
 
@@ -1221,50 +984,26 @@ describe "A method" do
       m(a: 1).should == [1, 1]
       m(a: 1, b: 2).should == [1, 2]
       suppress_keyword_warning do
-        -> { m("a" => 1, a: 1, b: 2) }.should raise_error(ArgumentError)
+        -> { m("a" => 1, a: 1, b: 2) }.should.raise(ArgumentError)
       end
     end
 
-    ruby_version_is ''...'2.7' do
-      evaluate <<-ruby do
-          def m(a:, **) a end
-        ruby
-
-        m(a: 1).should == 1
-        m(a: 1, b: 2).should == 1
-        -> { m("a" => 1, a: 1, b: 2) }.should raise_error(ArgumentError)
-      end
-
-      evaluate <<-ruby do
-          def m(a:, **k) [a, k] end
-        ruby
+    evaluate <<-ruby do
+        def m(a:, **) a end
+      ruby
 
-        m(a: 1).should == [1, {}]
-        m(a: 1, b: 2, c: 3).should == [1, {b: 2, c: 3}]
-        -> { m("a" => 1, a: 1, b: 2) }.should raise_error(ArgumentError)
-      end
+      m(a: 1).should == 1
+      m(a: 1, b: 2).should == 1
+      m("a" => 1, a: 1, b: 2).should == 1
     end
 
-    ruby_version_is '2.7' do
-      evaluate <<-ruby do
-          def m(a:, **) a end
-        ruby
-
-        m(a: 1).should == 1
-        m(a: 1, b: 2).should == 1
-        m("a" => 1, a: 1, b: 2).should == 1
-      end
-
-      evaluate <<-ruby do
-          def m(a:, **k) [a, k] end
-        ruby
+    evaluate <<-ruby do
+        def m(a:, **k) [a, k] end
+      ruby
 
-        m(a: 1).should == [1, {}]
-        m(a: 1, b: 2, c: 3).should == [1, {b: 2, c: 3}]
-        suppress_warning do
-          m("a" => 1, a: 1, b: 2).should == [1, {"a" => 1, b: 2}]
-        end
-      end
+      m(a: 1).should == [1, {}]
+      m(a: 1, b: 2, c: 3).should == [1, {b: 2, c: 3}]
+      m("a" => 1, a: 1, b: 2).should == [1, {"a" => 1, b: 2}]
     end
 
     evaluate <<-ruby do
@@ -1362,6 +1101,28 @@ describe "A method" do
     end
 
     evaluate <<-ruby do
+      def m(**nil); :ok; end;
+      ruby
+
+      m().should == :ok
+      -> { m(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { m(**{a: 1}) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { m("a" => 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    end
+
+    evaluate <<-ruby do
+      def m(a, **nil); a end;
+      ruby
+
+      m({a: 1}).should == {a: 1}
+      m({"a" => 1}).should == {"a" => 1}
+
+      -> { m(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { m(**{a: 1}) }.should.raise(ArgumentError, 'no keywords accepted')
+      -> { m("a" => 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    end
+
+    evaluate <<-ruby do
         def m(a, b = nil, c = nil, d, e: nil, **f)
           [a, b, c, d, e, f]
         end
@@ -1370,28 +1131,93 @@ describe "A method" do
       result = m(1, 2)
       result.should == [1, nil, nil, 2, nil, {}]
 
-      suppress_warning do
-        result = m(1, 2, {foo: :bar})
-        result.should == [1, nil, nil, 2, nil, {foo: :bar}]
-      end
+      result = m(1, 2, {foo: :bar})
+      result.should == [1, 2, nil, {foo: :bar}, nil, {}]
 
       result = m(1, {foo: :bar})
       result.should == [1, nil, nil, {foo: :bar}, nil, {}]
     end
+
+    ruby_version_is "4.1" do
+      evaluate <<-ruby do
+        def m(a, &nil); a end;
+        ruby
+
+        m(1).should == 1
+
+        -> { m(1) {} }.should.raise(ArgumentError, 'no block accepted')
+        -> { m(1, &proc {}) }.should.raise(ArgumentError, 'no block accepted')
+      end
+    end
+  end
+
+  context 'when passing an empty keyword splat to a method that does not accept keywords' do
+    evaluate <<-ruby do
+        def m(*a); a; end
+      ruby
+
+      h = {}
+      m(**h).should == []
+    end
+  end
+
+  context 'when passing an empty keyword splat to a method that does not accept keywords' do
+    evaluate <<-ruby do
+        def m(a); a; end
+      ruby
+      h = {}
+
+      -> do
+        m(**h).should == {}
+      end.should.raise(ArgumentError)
+    end
   end
 
-  context "assigns keyword arguments from a passed Hash without modifying it" do
+  context "raises ArgumentError if passing hash as keyword arguments" do
     evaluate <<-ruby do
         def m(a: nil); a; end
       ruby
 
       options = {a: 1}.freeze
       -> do
-        suppress_warning do
-          m(options).should == 1
-        end
-      end.should_not raise_error
-      options.should == {a: 1}
+        m(options)
+      end.should.raise(ArgumentError)
+    end
+  end
+
+  it "assigns the last Hash to the last optional argument if the Hash contains non-Symbol keys and is not passed as keywords" do
+    def m(a = nil, b = {}, v: false)
+      [a, b, v]
+    end
+
+    h = { "key" => "value" }
+    m(:a, h).should == [:a, h, false]
+    m(:a, h, v: true).should == [:a, h, true]
+    m(v: true).should == [nil, {}, true]
+  end
+end
+
+context "when passing **nil into a method that accepts keyword arguments" do
+  ruby_version_is ""..."3.4" do
+    it "raises TypeError" do
+      def m(**kw) kw; end
+
+      h = nil
+      -> { m(a: 1, **h) }.should.raise(TypeError, "no implicit conversion of nil into Hash")
+      -> { m(a: 1, **nil) }.should.raise(TypeError, "no implicit conversion of nil into Hash")
+    end
+  end
+
+  ruby_version_is "3.4" do
+    it "expands nil using ** into {}" do
+      def m(**kw) kw; end
+
+      h = nil
+      m(**h).should == {}
+      m(a: 1, **h).should == {a: 1}
+
+      m(**nil).should == {}
+      m(a: 1, **nil).should == {a: 1}
     end
   end
 end
@@ -1414,22 +1240,48 @@ describe "A method call with a space between method name and parentheses" do
     end
   end
 
-  context "when a single argument provided" do
-    it "assigns it" do
+  context "when a single argument is provided" do
+    it "assigns a simple expression" do
+      args = m (1)
+      args.should == [1]
+    end
+
+    it "assigns an expression consisting of multiple statements" do
+      args = m ((0; 1))
+      args.should == [1]
+    end
+
+    it "assigns one single statement, without the need of parentheses" do
       args = m (1 == 1 ? true : false)
       args.should == [true]
     end
+
+    it "supports multiple statements" do
+      eval("m (1; 2)").should == [2]
+    end
+  end
+
+  context "when multiple arguments are provided" do
+    it "assigns simple expressions" do
+      args = m (1), (2)
+      args.should == [1, 2]
+    end
+
+    it "assigns expressions consisting of multiple statements" do
+      args = m ((0; 1)), ((2; 3))
+      args.should == [1, 3]
+    end
   end
 
-  context "when 2+ arguments provided" do
+  context "when the argument looks like an argument list" do
     it "raises a syntax error" do
       -> {
         eval("m (1, 2)")
-      }.should raise_error(SyntaxError)
+      }.should.raise(SyntaxError)
 
       -> {
         eval("m (1, 2, 3)")
-      }.should raise_error(SyntaxError)
+      }.should.raise(SyntaxError)
     end
   end
 
@@ -1485,3 +1337,333 @@ describe "An array-dereference method ([])" do
     end
   end
 end
+
+describe "An endless method definition" do
+  context "without arguments" do
+    evaluate <<-ruby do
+        def m() = 42
+      ruby
+
+      m.should == 42
+    end
+
+    context "without parenthesis" do
+      evaluate <<-ruby do
+        def m = 42
+      ruby
+
+        m.should == 42
+      end
+    end
+  end
+
+  context "with arguments" do
+    evaluate <<-ruby do
+        def m(a, b) = a + b
+      ruby
+
+      m(1, 4).should == 5
+    end
+  end
+
+  context "with multiline body" do
+    evaluate <<-ruby do
+        def m(n) =
+          if n > 2
+            m(n - 2) + m(n - 1)
+          else
+            1
+          end
+      ruby
+
+      m(6).should == 8
+    end
+  end
+
+  # tested more thoroughly in language/delegation_spec.rb
+  context "with args forwarding" do
+    evaluate <<-ruby do
+        def mm(word, num:)
+          word * num
+        end
+
+        def m(...) = mm(...) + mm(...)
+      ruby
+
+      m("meow", num: 2).should == "meow" * 4
+    end
+  end
+end
+
+describe "Keyword arguments are now separated from positional arguments" do
+  context "when the method has only positional parameters" do
+    it "treats incoming keyword arguments as positional for compatibility" do
+      def foo(a, b, c, hsh)
+        hsh[:key]
+      end
+
+      foo(1, 2, 3, key: 42).should == 42
+    end
+  end
+
+  context "when the method takes a ** parameter" do
+    it "captures the passed literal keyword arguments" do
+      def foo(a, b, c, **hsh)
+        hsh[:key]
+      end
+
+      foo(1, 2, 3, key: 42).should == 42
+    end
+
+    it "captures the passed ** keyword arguments" do
+      def foo(a, b, c, **hsh)
+        hsh[:key]
+      end
+
+      h = { key: 42 }
+      foo(1, 2, 3, **h).should == 42
+    end
+
+    it "does not convert a positional Hash to keyword arguments" do
+      def foo(a, b, c, **hsh)
+        hsh[:key]
+      end
+
+      -> {
+        foo(1, 2, 3, { key: 42 })
+      }.should.raise(ArgumentError, 'wrong number of arguments (given 4, expected 3)')
+    end
+  end
+
+  context "when the method takes a key: parameter" do
+    context "when it's called with a positional Hash and no **" do
+      it "raises ArgumentError" do
+        def foo(a, b, c, key: 1)
+          key
+        end
+
+        -> {
+          foo(1, 2, 3, { key: 42 })
+        }.should.raise(ArgumentError, 'wrong number of arguments (given 4, expected 3)')
+      end
+    end
+
+    context "when it's called with **" do
+      it "captures the passed keyword arguments" do
+        def foo(a, b, c, key: 1)
+          key
+        end
+
+        h = { key: 42 }
+        foo(1, 2, 3, **h).should == 42
+      end
+    end
+  end
+end
+
+describe "kwarg with omitted value in a method call" do
+  context "accepts short notation 'kwarg' in method call" do
+    evaluate <<-ruby do
+        def call(*args, **kwargs) = [args, kwargs]
+      ruby
+
+      a, b, c = 1, 2, 3
+      arr, h = call(a:)
+      h.should == {a: 1}
+      arr.should == []
+
+      arr, h = call(a:, b:, c:)
+      h.should == {a: 1, b: 2, c: 3}
+      arr.should == []
+
+      arr, h = call(a:, b: 10, c:)
+      h.should == {a: 1, b: 10, c: 3}
+      arr.should == []
+    end
+  end
+
+  context "with methods and local variables" do
+    evaluate <<-ruby do
+        def call(*args, **kwargs) = [args, kwargs]
+
+        def bar
+          "baz"
+        end
+
+        def foo(val)
+          call bar:, val:
+        end
+      ruby
+
+      foo(1).should == [[], {bar: "baz", val: 1}]
+    end
+  end
+end
+
+describe "Inside 'endless' method definitions" do
+  it "allows method calls without parenthesis" do
+    def greet(person) = "Hi, ".dup.concat person
+
+    greet("Homer").should == "Hi, Homer"
+  end
+end
+
+describe "warning about not used block argument" do
+  ruby_version_is "3.4" do
+    it "warns when passing a block argument to a method that never uses it" do
+      def m_that_does_not_use_block
+        42
+      end
+
+      -> {
+        m_that_does_not_use_block { }
+      }.should complain(
+        /#{__FILE__}:#{__LINE__ - 2}: warning: the block passed to 'm_that_does_not_use_block' defined at #{__FILE__}:#{__LINE__ - 7} may be ignored/,
+        verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that declares a block parameter" do
+      def m_with_block_parameter(&block)
+        42
+      end
+
+      -> { m_with_block_parameter { } }.should_not complain(verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that declares an anonymous block parameter" do
+      def m_with_anonymous_block_parameter(&)
+        42
+      end
+
+      -> { m_with_anonymous_block_parameter { } }.should_not complain(verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that yields an implicit block parameter" do
+      def m_with_yield
+        yield 42
+      end
+
+      -> { m_with_yield { } }.should_not complain(verbose: true)
+    end
+
+    it "warns when passing a block argument to a method that calls #block_given?" do
+      def m_with_block_given
+        block_given?
+      end
+
+      -> {
+        m_with_block_given { }
+      }.should complain(
+        /#{__FILE__}:#{__LINE__ - 2}: warning: the block passed to 'm_with_block_given' defined at #{__FILE__}:#{__LINE__ - 7} may be ignored/,
+        verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that calls super" do
+      parent = Class.new do
+        def m
+        end
+      end
+
+      child = Class.new(parent) do
+        def m
+          super
+        end
+      end
+
+      obj = child.new
+      -> { obj.m { } }.should_not complain(verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that calls super(...)" do
+      parent = Class.new do
+        def m(a)
+        end
+      end
+
+      child = Class.new(parent) do
+        def m(...)
+          super(...)
+        end
+      end
+
+      obj = child.new
+      -> { obj.m(42) { } }.should_not complain(verbose: true)
+    end
+
+    it "does not warn when called #initialize()" do
+      klass = Class.new do
+        def initialize
+        end
+      end
+
+      -> { klass.new {} }.should_not complain(verbose: true)
+    end
+
+    it "does not warn when passing a block argument to a method that calls super()" do
+      parent = Class.new do
+        def m
+        end
+      end
+
+      child = Class.new(parent) do
+        def m
+          super()
+        end
+      end
+
+      obj = child.new
+      -> { obj.m { } }.should_not complain(verbose: true)
+    end
+
+    it "warns only once per call site" do
+      def m_that_does_not_use_block
+        42
+      end
+
+      def call_m_that_does_not_use_block
+        m_that_does_not_use_block {}
+      end
+
+      -> {
+        m_that_does_not_use_block { }
+      }.should complain(/the block passed to 'm_that_does_not_use_block' defined at .+ may be ignored/, verbose: true)
+
+      -> {
+        m_that_does_not_use_block { }
+      }.should_not complain(verbose: true)
+    end
+
+    it "can be disabled with :strict_unused_block warning category" do
+      def m_that_does_not_use_block
+        42
+      end
+
+      # ensure that warning is emitted
+      -> { m_that_does_not_use_block { } }.should complain(verbose: true)
+
+      warn_strict_unused_block = Warning[:strict_unused_block]
+      Warning[:strict_unused_block] = false
+      begin
+        -> { m_that_does_not_use_block { } }.should_not complain(verbose: true)
+      ensure
+        Warning[:strict_unused_block] = warn_strict_unused_block
+      end
+    end
+
+    it "can be enabled with :strict_unused_block = true warning category in not verbose mode" do
+      def m_that_does_not_use_block
+        42
+      end
+
+      warn_strict_unused_block = Warning[:strict_unused_block]
+      Warning[:strict_unused_block] = true
+      begin
+        -> {
+          m_that_does_not_use_block { }
+      }.should complain(/the block passed to 'm_that_does_not_use_block' defined at .+ may be ignored/)
+      ensure
+        Warning[:strict_unused_block] = warn_strict_unused_block
+      end
+    end
+  end
+end
diff --git a/spec/ruby/language/module_spec.rb b/spec/ruby/language/module_spec.rb
index 1b41e184bb..2f22e383d5 100644
--- a/spec/ruby/language/module_spec.rb
+++ b/spec/ruby/language/module_spec.rb
@@ -4,75 +4,105 @@ require_relative 'fixtures/module'
 describe "The module keyword" do
   it "creates a new module without semicolon" do
     module ModuleSpecsKeywordWithoutSemicolon end
-    ModuleSpecsKeywordWithoutSemicolon.should be_an_instance_of(Module)
+    ModuleSpecsKeywordWithoutSemicolon.should.instance_of?(Module)
   end
 
   it "creates a new module with a non-qualified constant name" do
     module ModuleSpecsToplevel; end
-    ModuleSpecsToplevel.should be_an_instance_of(Module)
+    ModuleSpecsToplevel.should.instance_of?(Module)
   end
 
   it "creates a new module with a qualified constant name" do
     module ModuleSpecs::Nested; end
-    ModuleSpecs::Nested.should be_an_instance_of(Module)
+    ModuleSpecs::Nested.should.instance_of?(Module)
   end
 
   it "creates a new module with a variable qualified constant name" do
     m = Module.new
     module m::N; end
-    m::N.should be_an_instance_of(Module)
+    m::N.should.instance_of?(Module)
   end
 
   it "reopens an existing module" do
     module ModuleSpecs; Reopened = true; end
-    ModuleSpecs::Reopened.should be_true
+    ModuleSpecs::Reopened.should == true
+  ensure
+    ModuleSpecs.send(:remove_const, :Reopened)
   end
 
-  it "reopens a module included in Object" do
-    module IncludedModuleSpecs; Reopened = true; end
-    ModuleSpecs::IncludedInObject::IncludedModuleSpecs::Reopened.should be_true
+  it "does not reopen a module included in Object" do
+    ruby_exe(<<~RUBY).should == "false"
+      module IncludedInObject
+        module IncludedModule; end
+      end
+      class Object
+        include IncludedInObject
+      end
+      module IncludedModule; end
+      print IncludedInObject::IncludedModule == Object::IncludedModule
+    RUBY
+  end
+
+  it "does not reopen a module included in non-Object modules" do
+    ruby_exe(<<~RUBY).should == "false/false"
+      module Included
+        module IncludedModule; end
+      end
+      module M
+        include Included
+        module IncludedModule; end
+      end
+      class C
+        include Included
+        module IncludedModule; end
+      end
+      print Included::IncludedModule == M::IncludedModule, "/",
+            Included::IncludedModule == C::IncludedModule
+    RUBY
   end
 
   it "raises a TypeError if the constant is a Class" do
     -> do
       module ModuleSpecs::Modules::Klass; end
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a TypeError if the constant is a String" do
-    -> { module ModuleSpecs::Modules::A; end }.should raise_error(TypeError)
+    -> { module ModuleSpecs::Modules::A; end }.should.raise(TypeError)
   end
 
-  it "raises a TypeError if the constant is a Fixnum" do
-    -> { module ModuleSpecs::Modules::B; end }.should raise_error(TypeError)
+  it "raises a TypeError if the constant is an Integer" do
+    -> { module ModuleSpecs::Modules::B; end }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the constant is nil" do
-    -> { module ModuleSpecs::Modules::C; end }.should raise_error(TypeError)
+    -> { module ModuleSpecs::Modules::C; end }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the constant is true" do
-    -> { module ModuleSpecs::Modules::D; end }.should raise_error(TypeError)
+    -> { module ModuleSpecs::Modules::D; end }.should.raise(TypeError)
   end
 
   it "raises a TypeError if the constant is false" do
-    -> { module ModuleSpecs::Modules::D; end }.should raise_error(TypeError)
+    -> { module ModuleSpecs::Modules::D; end }.should.raise(TypeError)
   end
 end
 
 describe "Assigning an anonymous module to a constant" do
   it "sets the name of the module" do
     mod = Module.new
-    mod.name.should be_nil
+    mod.name.should == nil
 
     ::ModuleSpecs_CS1 = mod
     mod.name.should == "ModuleSpecs_CS1"
+  ensure
+    Object.send(:remove_const, :ModuleSpecs_CS1)
   end
 
-  it "does not set the name of a module scoped by an anonymous module" do
+  it "sets the name of a module scoped by an anonymous module" do
     a, b = Module.new, Module.new
     a::B = b
-    b.name.should be_nil
+    b.name.should.end_with? '::B'
   end
 
   it "sets the name of contained modules when assigning a toplevel anonymous module" do
@@ -87,5 +117,7 @@ describe "Assigning an anonymous module to a constant" do
     b.name.should == "ModuleSpecs_CS2::B"
     c.name.should == "ModuleSpecs_CS2::B::C"
     d.name.should == "ModuleSpecs_CS2::D"
+  ensure
+    Object.send(:remove_const, :ModuleSpecs_CS2)
   end
 end
diff --git a/spec/ruby/language/next_spec.rb b/spec/ruby/language/next_spec.rb
index 6fbfc4a54d..eac151eeb3 100644
--- a/spec/ruby/language/next_spec.rb
+++ b/spec/ruby/language/next_spec.rb
@@ -21,7 +21,7 @@ describe "The next statement from within the block" do
   end
 
   it "causes block to return nil if invoked with an empty expression" do
-    -> { next (); 456 }.call.should be_nil
+    -> { next (); 456 }.call.should == nil
   end
 
   it "returns the argument passed" do
@@ -111,7 +111,7 @@ describe "The next statement" do
     it "is invalid and raises a SyntaxError" do
       -> {
         eval("def m; next; end")
-      }.should raise_error(SyntaxError)
+      }.should.raise(SyntaxError)
     end
   end
 end
diff --git a/spec/ruby/language/not_spec.rb b/spec/ruby/language/not_spec.rb
index 052af9b256..23411a8e1d 100644
--- a/spec/ruby/language/not_spec.rb
+++ b/spec/ruby/language/not_spec.rb
@@ -2,50 +2,50 @@ require_relative '../spec_helper'
 
 describe "The not keyword" do
   it "negates a `true' value" do
-    (not true).should be_false
-    (not 'true').should be_false
+    (not true).should == false
+    (not 'true').should == false
   end
 
   it "negates a `false' value" do
-    (not false).should be_true
-    (not nil).should be_true
+    (not false).should == true
+    (not nil).should == true
   end
 
   it "accepts an argument" do
-    not(true).should be_false
+    not(true).should == false
   end
 
   it "returns false if the argument is true" do
-    (not(true)).should be_false
+    (not(true)).should == false
   end
 
   it "returns true if the argument is false" do
-    (not(false)).should be_true
+    (not(false)).should == true
   end
 
   it "returns true if the argument is nil" do
-    (not(nil)).should be_true
+    (not(nil)).should == true
   end
 end
 
 describe "The `!' keyword" do
   it "negates a `true' value" do
-    (!true).should be_false
-    (!'true').should be_false
+    (!true).should == false
+    (!'true').should == false
   end
 
   it "negates a `false' value" do
-    (!false).should be_true
-    (!nil).should be_true
+    (!false).should == true
+    (!nil).should == true
   end
 
   it "doubled turns a truthful object into `true'" do
-    (!!true).should be_true
-    (!!'true').should be_true
+    (!!true).should == true
+    (!!'true').should == true
   end
 
   it "doubled turns a not truthful object into `false'" do
-    (!!false).should be_false
-    (!!nil).should be_false
+    (!!false).should == false
+    (!!nil).should == false
   end
 end
diff --git a/spec/ruby/language/numbered_parameters_spec.rb b/spec/ruby/language/numbered_parameters_spec.rb
new file mode 100644
index 0000000000..23e89a14be
--- /dev/null
+++ b/spec/ruby/language/numbered_parameters_spec.rb
@@ -0,0 +1,113 @@
+require_relative '../spec_helper'
+
+describe "Numbered parameters" do
+  it "provides default parameters _1, _2, ... in a block" do
+    -> { _1 }.call("a").should == "a"
+    proc { _1 }.call("a").should == "a"
+    lambda { _1 }.call("a").should == "a"
+    ["a"].map { _1 }.should == ["a"]
+  end
+
+  it "assigns nil to not passed parameters" do
+    proc { [_1, _2] }.call("a").should == ["a", nil]
+    proc { [_1, _2] }.call("a", "b").should == ["a", "b"]
+  end
+
+  it "supports variables _1-_9 only for the first 9 passed parameters" do
+    block = proc { [_1, _2, _3, _4, _5, _6, _7, _8, _9] }
+    result = block.call(1, 2, 3, 4, 5, 6, 7, 8, 9)
+    result.should == [1, 2, 3, 4, 5, 6, 7, 8, 9]
+  end
+
+  it "does not support more than 9 parameters" do
+    -> {
+      proc { [_10] }.call(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+    }.should.raise(NameError, /undefined local variable or method [`']_10'/)
+  end
+
+  it "can not be used in both outer and nested blocks at the same time" do
+    -> {
+      eval("-> { _1; -> { _2 } }")
+    }.should.raise(SyntaxError, /numbered parameter is already used in/m)
+  end
+
+  it "cannot be overwritten with local variable" do
+    -> {
+      eval <<~CODE
+        _1 = 0
+        proc { _1 }.call("a").should == 0
+      CODE
+    }.should.raise(SyntaxError, /_1 is reserved for numbered parameter/)
+  end
+
+  it "errors when numbered parameter is overwritten with local variable" do
+    -> {
+      eval("_1 = 0")
+    }.should.raise(SyntaxError, /_1 is reserved for numbered parameter/)
+  end
+
+  it "raises SyntaxError when block parameters are specified explicitly" do
+    -> { eval("-> () { _1 }")         }.should.raise(SyntaxError, /ordinary parameter is defined/)
+    -> { eval("-> (x) { _1 }")        }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+    -> { eval("proc { || _1 }")       }.should.raise(SyntaxError, /ordinary parameter is defined/)
+    -> { eval("proc { |x| _1 }")      }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+    -> { eval("lambda { || _1 }")     }.should.raise(SyntaxError, /ordinary parameter is defined/)
+    -> { eval("lambda { |x| _1 }")    }.should.raise(SyntaxError, /ordinary parameter is defined/)
+
+    -> { eval("['a'].map { || _1 }")  }.should.raise(SyntaxError, /ordinary parameter is defined/)
+    -> { eval("['a'].map { |x| _1 }") }.should.raise(SyntaxError, /ordinary parameter is defined/)
+  end
+
+  describe "assigning to a numbered parameter" do
+    it "raises SyntaxError" do
+      -> { eval("proc { _1 = 0 }") }.should.raise(SyntaxError, /_1 is reserved for numbered parameter/)
+    end
+  end
+
+  it "affects block arity" do
+    -> { _1 }.arity.should == 1
+    -> { _2 }.arity.should == 2
+    -> { _3 }.arity.should == 3
+    -> { _4 }.arity.should == 4
+    -> { _5 }.arity.should == 5
+    -> { _6 }.arity.should == 6
+    -> { _7 }.arity.should == 7
+    -> { _8 }.arity.should == 8
+    -> { _9 }.arity.should == 9
+
+    ->     { _9 }.arity.should == 9
+    proc   { _9 }.arity.should == 9
+    lambda { _9 }.arity.should == 9
+  end
+
+  it "affects block parameters" do
+    -> { _1 }.parameters.should == [[:req, :_1]]
+    -> { _2 }.parameters.should == [[:req, :_1], [:req, :_2]]
+
+    proc { _1 }.parameters.should == [[:opt, :_1]]
+    proc { _2 }.parameters.should == [[:opt, :_1], [:opt, :_2]]
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "affects binding local variables" do
+      -> { _1; binding.local_variables }.call("a").should == [:_1]
+      -> { _2; binding.local_variables }.call("a", "b").should == [:_1, :_2]
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "does not affect binding local variables" do
+      -> { _1; binding.local_variables }.call("a").should == []
+      -> { _2; binding.local_variables }.call("a", "b").should == []
+    end
+  end
+
+  it "does not work in methods" do
+    obj = Object.new
+    def obj.foo; _1 end
+
+    -> { obj.foo("a") }.should.raise(ArgumentError, /wrong number of arguments/)
+  end
+end
diff --git a/spec/ruby/language/numbers_spec.rb b/spec/ruby/language/numbers_spec.rb
index c82a630632..ed0e49c048 100644
--- a/spec/ruby/language/numbers_spec.rb
+++ b/spec/ruby/language/numbers_spec.rb
@@ -11,7 +11,7 @@ describe "A number literal" do
   end
 
   it "cannot have a leading underscore" do
-    -> { eval("_4_2") }.should raise_error(NameError)
+    -> { eval("_4_2") }.should.raise(NameError)
   end
 
   it "can have a decimal point" do
@@ -20,8 +20,8 @@ describe "A number literal" do
 
   it "must have a digit before the decimal point" do
     0.75.should == 0.75
-    -> { eval(".75")  }.should raise_error(SyntaxError)
-    -> { eval("-.75") }.should raise_error(SyntaxError)
+    -> { eval(".75")  }.should.raise(SyntaxError)
+    -> { eval("-.75") }.should.raise(SyntaxError)
   end
 
   it "can have an exponent" do
@@ -45,7 +45,15 @@ describe "A number literal" do
     eval('-3r').should == Rational(-3, 1)
   end
 
-  it "can be an bignum literal with trailing 'r' to represent a Rational" do
+  it "can be an float literal with trailing 'r' to represent a Rational in a canonical form" do
+    eval('1.0r').should == Rational(1, 1)
+  end
+
+  it "can be a float literal with trailing 'r' to represent a Rational" do
+    eval('0.0174532925199432957r').should == Rational(174532925199432957, 10000000000000000000)
+  end
+
+  it "can be a bignum literal with trailing 'r' to represent a Rational" do
     eval('1111111111111111111111111111111111111111111111r').should == Rational(1111111111111111111111111111111111111111111111, 1)
     eval('-1111111111111111111111111111111111111111111111r').should == Rational(-1111111111111111111111111111111111111111111111, 1)
   end
diff --git a/spec/ruby/language/optional_assignments_spec.rb b/spec/ruby/language/optional_assignments_spec.rb
index 3d9e0dbb65..ebb5d36351 100644
--- a/spec/ruby/language/optional_assignments_spec.rb
+++ b/spec/ruby/language/optional_assignments_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../spec_helper'
+require_relative '../fixtures/constants'
 
 describe 'Optional variable assignments' do
   describe 'using ||=' do
@@ -56,7 +57,7 @@ describe 'Optional variable assignments' do
       end
     end
 
-    describe 'using a accessor' do
+    describe 'using an accessor' do
       before do
         klass = Class.new { attr_accessor :b }
         @a    = klass.new
@@ -102,6 +103,16 @@ describe 'Optional variable assignments' do
         @a.b.should == 10
       end
 
+      it 'does evaluate receiver only once when assigns' do
+        ScratchPad.record []
+        @a.b = nil
+
+        (ScratchPad << :evaluated; @a).b ||= 10
+
+        ScratchPad.recorded.should == [:evaluated]
+        @a.b.should == 10
+      end
+
       it 'returns the new value if set to false' do
         def @a.b=(x)
           :v
@@ -121,29 +132,148 @@ describe 'Optional variable assignments' do
         (@a.b ||= 20).should == 10
       end
 
-      it 'works when writer is private' do
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(v) @a = v end
+          def public_method(v); self.a ||= v end
+          private
+          def a; @a end
+          def a=(v) @a = v; 42 end
+        end
+
+        a = klass_with_private_methods.new(false)
+        a.public_method(10).should == 10
+      end
+    end
+
+    describe 'using a #[]' do
+      before do
+        @a = {}
         klass = Class.new do
-          def t
-            self.b = false
-            (self.b ||= 10).should == 10
-            (self.b ||= 20).should == 10
+          def [](k)
+            @hash ||= {}
+            @hash[k]
           end
 
-          def b
-            @b
+          def []=(k, v)
+            @hash ||= {}
+            @hash[k] = v
+            7
           end
+        end
+        @b = klass.new
+      end
 
-          def b=(x)
-            @b = x
-            :v
+      it 'returns the assigned value, not the result of the []= method with ||=' do
+        (@b[:k] ||= 12).should == 12
+      end
+
+      it "evaluates the index precisely once" do
+        ary = [:x, :y]
+        @a[:x] = 15
+        @a[ary.pop] ||= 25
+        ary.should == [:x]
+        @a.should == { x: 15, y: 25 }
+      end
+
+      it "evaluates the index arguments in the correct order" do
+        ary = Class.new(Array) do
+          def [](x, y)
+            super(x + 3 * y)
+          end
+
+          def []=(x, y, value)
+            super(x + 3 * y, value)
           end
+        end.new
+        ary[0, 0] = 1
+        ary[1, 0] = 1
+        ary[2, 0] = nil
+        ary[3, 0] = 1
+        ary[4, 0] = 1
+        ary[5, 0] = 1
+        ary[6, 0] = nil
+
+        foo = [0, 2]
+
+        ary[foo.pop, foo.pop] ||= 2 # expected `ary[2, 0] ||= 2`
+
+        ary[2, 0].should == 2
+        ary[6, 0].should == nil # returns the same element as `ary[0, 2]`
+      end
+
+      it 'evaluates receiver only once when assigns' do
+        ScratchPad.record []
+        @a[:k] = nil
 
-          private :b=
+        (ScratchPad << :evaluated; @a)[:k] ||= 2
+
+        ScratchPad.recorded.should == [:evaluated]
+        @a[:k].should == 2
+      end
+
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(h) @a = h end
+          def public_method(k, v); self[k] ||= v end
+          private
+          def [](k) @a[k] end
+          def []=(k, v) @a[k] = v; 42 end
         end
 
-        klass.new.t
+        a = klass_with_private_methods.new(k: false)
+        a.public_method(:k, 10).should == 10
       end
 
+      context 'splatted argument' do
+        it 'correctly handles it' do
+          (@b[*[:m]] ||= 10).should == 10
+          @b[:m].should == 10
+
+          (@b[*(1; [:n])] ||= 10).should == 10
+          @b[:n].should == 10
+
+          (@b[*begin 1; [:k] end] ||= 10).should == 10
+          @b[:k].should == 10
+        end
+
+        it 'calls #to_a only once' do
+          k = Object.new
+          def k.to_a
+            ScratchPad << :to_a
+            [:k]
+          end
+
+          ScratchPad.record []
+          (@b[*k] ||= 20).should == 20
+          @b[:k].should == 20
+          ScratchPad.recorded.should == [:to_a]
+        end
+
+        it 'correctly handles a nested splatted argument' do
+          (@b[*[*[:k]]] ||= 20).should == 20
+          @b[:k].should == 20
+        end
+
+        it 'correctly handles multiple nested splatted arguments' do
+          klass_with_multiple_parameters = Class.new do
+            def [](k1, k2, k3)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"]
+            end
+
+            def []=(k1, k2, k3, v)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"] = v
+              7
+            end
+          end
+          a = klass_with_multiple_parameters.new
+
+          (a[*[:a], *[:b], *[:c]] ||= 20).should == 20
+          a[:a, :b, :c].should == 20
+        end
+      end
     end
   end
 
@@ -190,7 +320,7 @@ describe 'Optional variable assignments' do
       end
     end
 
-    describe 'using a single variable' do
+    describe 'using an accessor' do
       before do
         klass = Class.new { attr_accessor :b }
         @a    = klass.new
@@ -235,6 +365,29 @@ describe 'Optional variable assignments' do
 
         @a.b.should == 20
       end
+
+      it 'does evaluate receiver only once when assigns' do
+        ScratchPad.record []
+        @a.b = 10
+
+        (ScratchPad << :evaluated; @a).b &&= 20
+
+        ScratchPad.recorded.should == [:evaluated]
+        @a.b.should == 20
+      end
+
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(v) @a = v end
+          def public_method(v); self.a &&= v end
+          private
+          def a; @a end
+          def a=(v) @a = v; 42 end
+        end
+
+        a = klass_with_private_methods.new(true)
+        a.public_method(10).should == 10
+      end
     end
 
     describe 'using a #[]' do
@@ -296,13 +449,128 @@ describe 'Optional variable assignments' do
       end
 
       it 'returns the assigned value, not the result of the []= method with ||=' do
-        (@b[:k] ||= 12).should == 12
+        @b[:k] = 10
+        (@b[:k] &&= 12).should == 12
+      end
+
+      it "evaluates the index precisely once" do
+        ary = [:x, :y]
+        @a[:x] = 15
+        @a[:y] = 20
+        @a[ary.pop] &&= 25
+        ary.should == [:x]
+        @a.should == { x: 15, y: 25 }
+      end
+
+      it "evaluates the index arguments in the correct order" do
+        ary = Class.new(Array) do
+          def [](x, y)
+            super(x + 3 * y)
+          end
+
+          def []=(x, y, value)
+            super(x + 3 * y, value)
+          end
+        end.new
+        ary[0, 0] = 1
+        ary[1, 0] = 1
+        ary[2, 0] = 1
+        ary[3, 0] = 1
+        ary[4, 0] = 1
+        ary[5, 0] = 1
+        ary[6, 0] = 1
+
+        foo = [0, 2]
+
+        ary[foo.pop, foo.pop] &&= 2 # expected `ary[2, 0] &&= 2`
+
+        ary[2, 0].should == 2
+        ary[6, 0].should == 1 # returns the same element as `ary[0, 2]`
+      end
+
+      it 'evaluates receiver only once when assigns' do
+        ScratchPad.record []
+        @a[:k] = 1
+
+        (ScratchPad << :evaluated; @a)[:k] &&= 2
+
+        ScratchPad.recorded.should == [:evaluated]
+        @a[:k].should == 2
       end
 
       it 'returns the assigned value, not the result of the []= method with +=' do
         @b[:k] = 17
         (@b[:k] += 12).should == 29
       end
+
+      it 'ignores method visibility when receiver is self' do
+        klass_with_private_methods = Class.new do
+          def initialize(h) @a = h end
+          def public_method(k, v); self[k] &&= v end
+          private
+          def [](k) @a[k] end
+          def []=(k, v) @a[k] = v; 42 end
+        end
+
+        a = klass_with_private_methods.new(k: true)
+        a.public_method(:k, 10).should == 10
+      end
+
+      context 'splatted argument' do
+        it 'correctly handles it' do
+          @b[:m] = 0
+          (@b[*[:m]] &&= 10).should == 10
+          @b[:m].should == 10
+
+          @b[:n] = 0
+          (@b[*(1; [:n])] &&= 10).should == 10
+          @b[:n].should == 10
+
+          @b[:k] = 0
+          (@b[*begin 1; [:k] end] &&= 10).should == 10
+          @b[:k].should == 10
+        end
+
+        it 'calls #to_a only once' do
+          k = Object.new
+          def k.to_a
+            ScratchPad << :to_a
+            [:k]
+          end
+
+          ScratchPad.record []
+          @b[:k] = 10
+          (@b[*k] &&= 20).should == 20
+          @b[:k].should == 20
+          ScratchPad.recorded.should == [:to_a]
+        end
+
+        it 'correctly handles a nested splatted argument' do
+          @b[:k] = 10
+          (@b[*[*[:k]]] &&= 20).should == 20
+          @b[:k].should == 20
+        end
+
+        it 'correctly handles multiple nested splatted arguments' do
+          klass_with_multiple_parameters = Class.new do
+            def [](k1, k2, k3)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"]
+            end
+
+            def []=(k1, k2, k3, v)
+              @hash ||= {}
+              @hash[:"#{k1}#{k2}#{k3}"] = v
+              7
+            end
+          end
+          a = klass_with_multiple_parameters.new
+
+          a[:a, :b, :c] = 10
+          (a[*[:a], *[:b], *[:c]] &&= 20).should == 20
+          a[:a, :b, :c].should == 20
+        end
+      end
     end
   end
 
@@ -335,7 +603,7 @@ describe 'Optional variable assignments' do
     end
 
     it 'with &&= assignments will fail with non-existent constants' do
-      -> { Object::A &&= 10 }.should raise_error(NameError)
+      -> { Object::A &&= 10 }.should.raise(NameError)
     end
 
     it 'with operator assignments' do
@@ -347,7 +615,128 @@ describe 'Optional variable assignments' do
     end
 
     it 'with operator assignments will fail with non-existent constants' do
-      -> { Object::A += 10 }.should raise_error(NameError)
+      -> { Object::A += 10 }.should.raise(NameError)
+    end
+  end
+end
+
+describe 'Optional constant assignment' do
+  describe 'with ||=' do
+    it "assigns a scoped constant if previously undefined" do
+      ConstantSpecs.should_not.const_defined?(:OpAssignUndefined)
+      module ConstantSpecs
+        OpAssignUndefined ||= 42
+      end
+      ConstantSpecs::OpAssignUndefined.should == 42
+      ConstantSpecs::OpAssignUndefinedOutside ||= 42
+      ConstantSpecs::OpAssignUndefinedOutside.should == 42
+      ConstantSpecs.send(:remove_const, :OpAssignUndefined)
+      ConstantSpecs.send(:remove_const, :OpAssignUndefinedOutside)
+    end
+
+    it "assigns a global constant if previously undefined" do
+      OpAssignGlobalUndefined ||= 42
+      ::OpAssignGlobalUndefinedExplicitScope ||= 42
+      OpAssignGlobalUndefined.should == 42
+      ::OpAssignGlobalUndefinedExplicitScope.should == 42
+      Object.send :remove_const, :OpAssignGlobalUndefined
+      Object.send :remove_const, :OpAssignGlobalUndefinedExplicitScope
+    end
+
+    it 'correctly defines non-existing constants' do
+      ConstantSpecs::ClassA::OR_ASSIGNED_CONSTANT1 ||= :assigned
+      ConstantSpecs::ClassA::OR_ASSIGNED_CONSTANT1.should == :assigned
+    end
+
+    it 'correctly overwrites nil constants' do
+      suppress_warning do # already initialized constant
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT1 = nil
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT1 ||= :assigned
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT1.should == :assigned
+      end
+    end
+
+    it 'causes side-effects of the module part to be applied only once (for undefined constant)' do
+      x = 0
+      (x += 1; ConstantSpecs::ClassA)::OR_ASSIGNED_CONSTANT2 ||= :assigned
+      x.should == 1
+      ConstantSpecs::ClassA::OR_ASSIGNED_CONSTANT2.should == :assigned
+    end
+
+    it 'causes side-effects of the module part to be applied only once (for nil constant)' do
+      suppress_warning do # already initialized constant
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT2 = nil
+      x = 0
+      (x += 1; ConstantSpecs::ClassA)::NIL_OR_ASSIGNED_CONSTANT2 ||= :assigned
+      x.should == 1
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT2.should == :assigned
+      end
+    end
+
+    it 'does not evaluate the right-hand side if the module part raises an exception (for undefined constant)' do
+      x = 0
+      y = 0
+
+      -> {
+        (x += 1; raise Exception; ConstantSpecs::ClassA)::OR_ASSIGNED_CONSTANT3 ||= (y += 1; :assigned)
+      }.should.raise(Exception)
+
+      x.should == 1
+      y.should == 0
+      defined?(ConstantSpecs::ClassA::OR_ASSIGNED_CONSTANT3).should == nil
+    end
+
+    it 'does not evaluate the right-hand side if the module part raises an exception (for nil constant)' do
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT3 = nil
+      x = 0
+      y = 0
+
+      -> {
+        (x += 1; raise Exception; ConstantSpecs::ClassA)::NIL_OR_ASSIGNED_CONSTANT3 ||= (y += 1; :assigned)
+      }.should.raise(Exception)
+
+      x.should == 1
+      y.should == 0
+      ConstantSpecs::ClassA::NIL_OR_ASSIGNED_CONSTANT3.should == nil
+    ensure
+      ConstantSpecs::ClassA.send(:remove_const, :NIL_OR_ASSIGNED_CONSTANT3)
+    end
+  end
+
+  describe "with &&=" do
+    it "re-assigns a scoped constant if already true" do
+      module ConstantSpecs
+        OpAssignTrue = true
+      end
+      suppress_warning do
+        ConstantSpecs::OpAssignTrue &&= 1
+      end
+      ConstantSpecs::OpAssignTrue.should == 1
+      ConstantSpecs.send :remove_const, :OpAssignTrue
+    end
+
+    it "leaves scoped constant if not true" do
+      module ConstantSpecs
+        OpAssignFalse = false
+      end
+      ConstantSpecs::OpAssignFalse &&= 1
+      ConstantSpecs::OpAssignFalse.should == false
+      ConstantSpecs.send :remove_const, :OpAssignFalse
+    end
+
+    it 'causes side-effects of the module part to be applied only once (when assigns)' do
+      module ConstantSpecs
+        OpAssignTrue = true
+      end
+
+      suppress_warning do # already initialized constant
+        x = 0
+        (x += 1; ConstantSpecs)::OpAssignTrue &&= :assigned
+        x.should == 1
+        ConstantSpecs::OpAssignTrue.should == :assigned
+      end
+
+      ConstantSpecs.send :remove_const, :OpAssignTrue
     end
   end
 end
diff --git a/spec/ruby/language/or_spec.rb b/spec/ruby/language/or_spec.rb
index fb75e788f1..8ae577a142 100644
--- a/spec/ruby/language/or_spec.rb
+++ b/spec/ruby/language/or_spec.rb
@@ -26,24 +26,24 @@ describe "The || operator" do
   end
 
   it "treats empty expressions as nil" do
-    (() || true).should be_true
-    (() || false).should be_false
-    (true || ()).should be_true
-    (false || ()).should be_nil
-    (() || ()).should be_nil
+    (() || true).should == true
+    (() || false).should == false
+    (true || ()).should == true
+    (false || ()).should == nil
+    (() || ()).should == nil
   end
 
   it "has a higher precedence than 'break' in 'break true || false'" do
     # see also 'break true or false' below
-    -> { break false || true }.call.should be_true
+    -> { break false || true }.call.should == true
   end
 
   it "has a higher precedence than 'next' in 'next true || false'" do
-    -> { next false || true }.call.should be_true
+    -> { next false || true }.call.should == true
   end
 
   it "has a higher precedence than 'return' in 'return true || false'" do
-    -> { return false || true }.call.should be_true
+    -> { return false || true }.call.should == true
   end
 end
 
@@ -68,23 +68,23 @@ describe "The or operator" do
   end
 
   it "treats empty expressions as nil" do
-    (() or true).should be_true
-    (() or false).should be_false
-    (true or ()).should be_true
-    (false or ()).should be_nil
-    (() or ()).should be_nil
+    (() or true).should == true
+    (() or false).should == false
+    (true or ()).should == true
+    (false or ()).should == nil
+    (() or ()).should == nil
   end
 
   it "has a lower precedence than 'break' in 'break true or false'" do
     # see also 'break true || false' above
-    -> { eval "break true or false" }.should raise_error(SyntaxError, /void value expression/)
+    -> { eval "break true or false" }.should.raise(SyntaxError, /void value expression/)
   end
 
   it "has a lower precedence than 'next' in 'next true or false'" do
-    -> { eval "next true or false" }.should raise_error(SyntaxError, /void value expression/)
+    -> { eval "next true or false" }.should.raise(SyntaxError, /void value expression/)
   end
 
   it "has a lower precedence than 'return' in 'return true or false'" do
-    -> { eval "return true or false" }.should raise_error(SyntaxError, /void value expression/)
+    -> { eval "return true or false" }.should.raise(SyntaxError, /void value expression/)
   end
 end
diff --git a/spec/ruby/language/pattern_matching_spec.rb b/spec/ruby/language/pattern_matching_spec.rb
new file mode 100644
index 0000000000..a24500c9fd
--- /dev/null
+++ b/spec/ruby/language/pattern_matching_spec.rb
@@ -0,0 +1,1310 @@
+require_relative '../spec_helper'
+
+describe "Pattern matching" do
+  before :each do
+    ScratchPad.record []
+  end
+
+  describe "Rightward assignment (`=>`) that can be standalone assoc operator that" do
+    it "deconstructs value" do
+      suppress_warning do
+        [0, 1] => [a, b]
+        [a, b].should == [0, 1]
+      end
+    end
+
+    it "deconstructs value and properly scopes variables" do
+      suppress_warning do
+        a = nil
+        1.times {
+          [0, 1] => [a, b]
+        }
+        [a, defined?(b)].should == [0, nil]
+      end
+    end
+
+    it "can work with keywords" do
+      { a: 0, b: 1 } => { a:, b: }
+      [a, b].should == [0, 1]
+    end
+  end
+
+  describe "One-line pattern matching" do
+    it "can be used to check if a pattern matches for Array-like entities" do
+      ([0, 1] in [a, b]).should == true
+      ([0, 1] in [a, b, c]).should == false
+    end
+
+    it "can be used to check if a pattern matches for Hash-like entities" do
+      ({ a: 0, b: 1 } in { a:, b: }).should == true
+      ({ a: 0, b: 1 } in { a:, b:, c: }).should == false
+    end
+  end
+
+  describe "find pattern" do
+    it "captures preceding elements to the pattern" do
+      case [0, 1, 2, 3]
+      in [*pre, 2, 3]
+        pre
+      else
+        false
+      end.should == [0, 1]
+    end
+
+    it "captures following elements to the pattern" do
+      case [0, 1, 2, 3]
+      in [0, 1, *post]
+        post
+      else
+        false
+      end.should == [2, 3]
+    end
+
+    it "captures both preceding and following elements to the pattern" do
+      case [0, 1, 2, 3, 4]
+      in [*pre, 2, *post]
+        [pre, post]
+      else
+        false
+      end.should == [[0, 1], [3, 4]]
+    end
+
+    it "can capture the entirety of the pattern" do
+      case [0, 1, 2, 3, 4]
+      in [*everything]
+        everything
+      else
+        false
+      end.should == [0, 1, 2, 3, 4]
+    end
+
+    it "will match an empty Array-like structure" do
+      case []
+      in [*everything]
+        everything
+      else
+        false
+      end.should == []
+    end
+
+    it "can be nested" do
+      case [0, [2, 4, 6], [3, 9, 27], [4, 16, 64]]
+      in [*pre, [*, 9, a], *post]
+        [pre, post, a]
+      else
+        false
+      end.should == [[0, [2, 4, 6]], [[4, 16, 64]], 27]
+    end
+
+    it "can be nested with an array pattern" do
+      case [0, [2, 4, 6], [3, 9, 27], [4, 16, 64]]
+      in [_, _, [*, 9, *], *post]
+        post
+      else
+        false
+      end.should == [[4, 16, 64]]
+    end
+
+    it "can be nested within a hash pattern" do
+      case {a: [3, 9, 27]}
+      in {a: [*, 9, *post]}
+        post
+      else
+        false
+      end.should == [27]
+    end
+
+    it "can nest hash and array patterns" do
+      case [0, {a: 42, b: [0, 1]}, {a: 42, b: [1, 2]}]
+      in [*, {a:, b: [1, c]}, *]
+        [a, c]
+      else
+        false
+      end.should == [42, 2]
+    end
+  end
+
+  it "extends case expression with case/in construction" do
+    case [0, 1]
+    in [0]
+      :foo
+    in [0, 1]
+      :bar
+    end.should == :bar
+  end
+
+  it "allows using then operator" do
+    case [0, 1]
+    in [0] then :foo
+    in [0, 1] then :bar
+    end.should == :bar
+  end
+
+  describe "warning" do
+    before :each do
+      @experimental, Warning[:experimental] = Warning[:experimental], true
+    end
+
+    after :each do
+      Warning[:experimental] = @experimental
+    end
+
+    context 'when regular form' do
+      before :each do
+        @src = 'case [0, 1]; in [a, b]; end'
+      end
+
+      it "does not warn about pattern matching is experimental feature" do
+        -> { eval @src }.should_not complain
+      end
+    end
+
+    context 'when one-line form' do
+      before :each do
+        @src = '[0, 1] => [a, b]'
+      end
+
+      it "does not warn about pattern matching is experimental feature" do
+        -> { eval @src }.should_not complain
+      end
+    end
+  end
+
+  it "binds variables" do
+    case [0, 1]
+    in [0, a]
+      a
+    end.should == 1
+  end
+
+  it "cannot mix in and when operators" do
+    -> {
+      eval <<~RUBY
+        case []
+        when 1 == 1
+        in []
+        end
+      RUBY
+    }.should.raise(SyntaxError, /syntax error, unexpected `in'|\(eval\):3: syntax error, unexpected keyword_in|unexpected 'in'/)
+
+    -> {
+      eval <<~RUBY
+        case []
+        in []
+        when 1 == 1
+        end
+      RUBY
+    }.should.raise(SyntaxError, /syntax error, unexpected `when'|\(eval\):3: syntax error, unexpected keyword_when|unexpected 'when'/)
+  end
+
+  it "checks patterns until the first matching" do
+    case [0, 1]
+    in [0]
+      :foo
+    in [0, 1]
+      :bar
+    in [0, 1]
+      :baz
+    end.should == :bar
+  end
+
+  it "executes else clause if no pattern matches" do
+    case [0, 1]
+    in [0]
+      true
+    else
+      false
+    end.should == false
+  end
+
+  it "raises NoMatchingPatternError if no pattern matches and no else clause" do
+    -> {
+      case [0, 1]
+      in [0]
+      end
+    }.should.raise(NoMatchingPatternError, /\[0, 1\]/)
+
+    error_pattern = ruby_version_is("3.4") ? /\{a: 0, b: 1\}/ : /\{:a=>0, :b=>1\}/
+    -> {
+      case {a: 0, b: 1}
+      in a: 1, b: 1
+      end
+    }.should.raise(NoMatchingPatternError, error_pattern)
+  end
+
+  it "raises NoMatchingPatternError if no pattern matches and evaluates the expression only once" do
+    evals = 0
+    -> {
+      case (evals += 1; [0, 1])
+      in [0]
+      end
+    }.should.raise(NoMatchingPatternError, /\[0, 1\]/)
+    evals.should == 1
+  end
+
+  it "does not allow calculation or method calls in a pattern" do
+    -> {
+      eval <<~RUBY
+        case 0
+        in 1 + 1
+          true
+        end
+      RUBY
+    }.should.raise(SyntaxError, /unexpected|expected a delimiter after the patterns of an `in` clause/)
+  end
+
+  it "evaluates the case expression once for multiple patterns, caching the result" do
+    case (ScratchPad << :foo; 1)
+    in 0
+      false
+    in 1
+      true
+    end.should == true
+
+    ScratchPad.recorded.should == [:foo]
+  end
+
+  describe "guards" do
+    it "supports if guard" do
+      case 0
+      in 0 if false
+        true
+      else
+        false
+      end.should == false
+
+      case 0
+      in 0 if true
+        true
+      else
+        false
+      end.should == true
+    end
+
+    it "supports unless guard" do
+      case 0
+      in 0 unless true
+        true
+      else
+        false
+      end.should == false
+
+      case 0
+      in 0 unless false
+        true
+      else
+        false
+      end.should == true
+    end
+
+    it "makes bound variables visible in guard" do
+      case [0, 1]
+      in [a, 1] if a >= 0
+        true
+      end.should == true
+    end
+
+    it "does not evaluate guard if pattern does not match" do
+      case 0
+      in 1 if (ScratchPad << :foo) || true
+      else
+      end
+
+      ScratchPad.recorded.should == []
+    end
+
+    it "takes guards into account when there are several matching patterns" do
+      case 0
+      in 0 if false
+        :foo
+      in 0 if true
+        :bar
+      end.should == :bar
+    end
+
+    it "executes else clause if no guarded pattern matches" do
+      case 0
+      in 0 if false
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "raises NoMatchingPatternError if no guarded pattern matches and no else clause" do
+      -> {
+        case [0, 1]
+        in [0, 1] if false
+        end
+      }.should.raise(NoMatchingPatternError, /\[0, 1\]/)
+    end
+  end
+
+  describe "value pattern" do
+    it "matches an object such that pattern === object" do
+      case 0
+      in 0
+        true
+      end.should == true
+
+      case 0
+      in (
+        -1..1)
+        true
+      end.should == true
+
+      case 0
+      in Integer
+        true
+      end.should == true
+
+      case "0"
+      in /0/
+        true
+      end.should == true
+
+      case "0"
+      in -> s { s == "0" }
+        true
+      end.should == true
+    end
+
+    it "allows string literal with interpolation" do
+      x = "x"
+
+      case "x"
+      in "#{x + ""}"
+        true
+      end.should == true
+    end
+  end
+
+  describe "variable pattern" do
+    it "matches a value and binds variable name to this value" do
+      case 0
+      in a
+        a
+      end.should == 0
+    end
+
+    it "makes bounded variable visible outside a case statement scope" do
+      case 0
+      in a
+      end
+
+      a.should == 0
+    end
+
+    it "create local variables even if a pattern doesn't match" do
+      case 0
+      in a
+      in b
+      in c
+      end
+
+      [a, b, c].should == [0, nil, nil]
+    end
+
+    it "allow using _ name to drop values" do
+      case [0, 1]
+      in [a, _]
+        a
+      end.should == 0
+    end
+
+    it "supports using _ in a pattern several times" do
+      case [0, 1, 2]
+      in [0, _, _]
+        true
+      end.should == true
+    end
+
+    it "supports using any name with _ at the beginning in a pattern several times" do
+      case [0, 1, 2]
+      in [0, _x, _x]
+        true
+      end.should == true
+
+      case {a: 0, b: 1, c: 2}
+      in {a: 0, b: _x, c: _x}
+        true
+      end.should == true
+    end
+
+    it "does not support using variable name (except _) several times" do
+      -> {
+        eval <<~RUBY
+          case [0]
+          in [a, a]
+          end
+        RUBY
+      }.should.raise(SyntaxError, /duplicated variable name/)
+    end
+
+    it "supports existing variables in a pattern specified with ^ operator" do
+      a = 0
+
+      case 0
+      in ^a
+        true
+      end.should == true
+    end
+
+    it "allows applying ^ operator to bound variables" do
+      case [1, 1]
+      in [n, ^n]
+        n
+      end.should == 1
+
+      case [1, 2]
+      in [n, ^n]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "requires bound variable to be specified in a pattern before ^ operator when it relies on a bound variable" do
+      -> {
+        eval <<~RUBY
+          case [1, 2]
+          in [^n, n]
+            true
+          else
+            false
+          end
+        RUBY
+      }.should.raise(SyntaxError, /n: no such local variable/)
+    end
+  end
+
+  describe "alternative pattern" do
+    it "matches if any of patterns matches" do
+      case 0
+      in 0 | 1 | 2
+        true
+      end.should == true
+    end
+
+    it "does not support variable binding" do
+      -> {
+        eval <<~RUBY
+          case [0, 1]
+          in [0, 0] | [0, a]
+          end
+        RUBY
+      }.should.raise(SyntaxError)
+    end
+
+    it "support underscore prefixed variables in alternation" do
+      case [0, 1]
+      in [1, _]
+        false
+      in [0, 0] | [0, _a]
+        true
+      end.should == true
+    end
+
+    it "can be used as a nested pattern" do
+      case [[1], ["2"]]
+      in [[0] | nil, _]
+        false
+      in [[1], [1]]
+        false
+      in [[1], [2 | "2"]]
+        true
+      end.should == true
+
+      case [1, 2]
+      in [0, _] | {a: 0}
+        false
+      in {a: 1, b: 2} | [1, 2]
+        true
+      end.should == true
+    end
+  end
+
+  describe "AS pattern" do
+    it "binds a variable to a value if pattern matches" do
+      case 0
+      in Integer => n
+        n
+      end.should == 0
+    end
+
+    it "can be used as a nested pattern" do
+      case [1, [2, 3]]
+      in [1, Array => ary]
+        ary
+      end.should == [2, 3]
+    end
+  end
+
+  describe "Array pattern" do
+    it "supports form Constant(pat, pat, ...)" do
+      case [0, 1, 2]
+      in Array(0, 1, 2)
+        true
+      end.should == true
+    end
+
+    it "supports form Constant[pat, pat, ...]" do
+      case [0, 1, 2]
+      in Array[0, 1, 2]
+        true
+      end.should == true
+    end
+
+    it "supports form [pat, pat, ...]" do
+      case [0, 1, 2]
+      in [0, 1, 2]
+        true
+      end.should == true
+    end
+
+    it "supports form pat, pat, ..." do
+      case [0, 1, 2]
+      in 0, 1, 2
+        true
+      end.should == true
+
+      case [0, 1, 2]
+      in 0, a, 2
+        a
+      end.should == 1
+
+      case [0, 1, 2]
+      in 0, *rest
+        rest
+      end.should == [1, 2]
+    end
+
+    it "matches an object with #deconstruct method which returns an array and each element in array matches element in pattern" do
+      obj = Object.new
+
+      def obj.deconstruct
+        [0, 1]
+      end
+
+      case obj
+      in [Integer, Integer]
+        true
+      end.should == true
+    end
+
+    it "calls #deconstruct once for multiple patterns, caching the result" do
+      obj = Object.new
+
+      def obj.deconstruct
+        ScratchPad << :deconstruct
+        [0, 1]
+      end
+
+      case obj
+      in [1, 2]
+        false
+      in [0, 1]
+        true
+      end.should == true
+
+      ScratchPad.recorded.should == [:deconstruct]
+    end
+
+    it "calls #deconstruct even on objects that are already an array" do
+      obj = [1, 2]
+
+      def obj.deconstruct
+        ScratchPad << :deconstruct
+        [3, 4]
+      end
+
+      case obj
+      in [3, 4]
+        true
+      else
+        false
+      end.should == true
+
+      ScratchPad.recorded.should == [:deconstruct]
+    end
+
+    it "does not match object if Constant === object returns false" do
+      case [0, 1, 2]
+      in String[0, 1, 2]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "checks Constant === object before calling #deconstruct" do
+      c1 = Class.new
+      obj = c1.new
+      obj.should_not_receive(:deconstruct)
+
+      case obj
+      in String[1]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "does not match object without #deconstruct method" do
+      obj = Object.new
+      obj.should_receive(:respond_to?).with(:deconstruct)
+
+      case obj
+      in Object[]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "raises TypeError if #deconstruct method does not return array" do
+      obj = Object.new
+
+      def obj.deconstruct
+        ""
+      end
+
+      -> {
+        case obj
+        in Object[]
+        else
+        end
+      }.should.raise(TypeError, /deconstruct must return Array/)
+    end
+
+    it "accepts a subclass of Array from #deconstruct" do
+      obj = Object.new
+
+      def obj.deconstruct
+        Class.new(Array).new([0, 1])
+      end
+
+      case obj
+      in [1, 2]
+        false
+      in [0, 1]
+        true
+      end.should == true
+    end
+
+    it "does not match object if elements of array returned by #deconstruct method does not match elements in pattern" do
+      obj = Object.new
+
+      def obj.deconstruct
+        [1]
+      end
+
+      case obj
+      in Object[0]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "binds variables" do
+      case [0, 1, 2]
+      in [a, b, c]
+        [a, b, c]
+      end.should == [0, 1, 2]
+    end
+
+    it "supports splat operator *rest" do
+      case [0, 1, 2]
+      in [0, *rest]
+        rest
+      end.should == [1, 2]
+    end
+
+    it "does not match partially by default" do
+      case [0, 1, 2, 3]
+      in [1, 2]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "does match partially from the array beginning if list + , syntax used" do
+      case [0, 1, 2, 3]
+      in [0, 1, ]
+        true
+      end.should == true
+
+      case [0, 1, 2, 3]
+      in 0, 1,;
+        true
+      end.should == true
+    end
+
+    it "matches [] with []" do
+      case []
+      in []
+        true
+      end.should == true
+    end
+
+    it "matches anything with *" do
+      case [0, 1]
+      in *;
+        true
+      end.should == true
+    end
+
+    it "can be used as a nested pattern" do
+      case [[1], ["2"]]
+      in [[0] | nil, _]
+        false
+      in [[1], [1]]
+        false
+      in [[1], [2 | "2"]]
+        true
+      end.should == true
+
+      case [1, 2]
+      in [0, _] | {a: 0}
+        false
+      in {a: 1, b: 2} | [1, 2]
+        true
+      end.should == true
+    end
+  end
+
+  describe "Hash pattern" do
+    it "supports form Constant(id: pat, id: pat, ...)" do
+      case {a: 0, b: 1}
+      in Hash(a: 0, b: 1)
+        true
+      end.should == true
+    end
+
+    it "supports form Constant[id: pat, id: pat, ...]" do
+      case {a: 0, b: 1}
+      in Hash[a: 0, b: 1]
+        true
+      end.should == true
+    end
+
+    it "supports form {id: pat, id: pat, ...}" do
+      case {a: 0, b: 1}
+      in {a: 0, b: 1}
+        true
+      end.should == true
+    end
+
+    it "supports form id: pat, id: pat, ..." do
+      case {a: 0, b: 1}
+      in a: 0, b: 1
+        true
+      end.should == true
+
+      case {a: 0, b: 1}
+      in a: a, b: b
+        [a, b]
+      end.should == [0, 1]
+
+      case {a: 0, b: 1, c: 2}
+      in a: 0, **rest
+        rest
+      end.should == {b: 1, c: 2}
+    end
+
+    it "supports a: which means a: a" do
+      case {a: 0, b: 1}
+      in Hash(a:, b:)
+        [a, b]
+      end.should == [0, 1]
+
+      a = b = nil
+
+      case {a: 0, b: 1}
+      in Hash[a:, b:]
+        [a, b]
+      end.should == [0, 1]
+
+      a = b = nil
+
+      case {a: 0, b: 1}
+      in {a:, b:}
+        [a, b]
+      end.should == [0, 1]
+
+      a = nil
+
+      case {a: 0, b: 1, c: 2}
+      in {a:, **rest}
+        [a, rest]
+      end.should == [0, {b: 1, c: 2}]
+
+      a = b = nil
+
+      case {a: 0, b: 1}
+      in a:, b:
+        [a, b]
+      end.should == [0, 1]
+    end
+
+    it "can mix key (a:) and key-value (a: b) declarations" do
+      case {a: 0, b: 1}
+      in Hash(a:, b: x)
+        [a, x]
+      end.should == [0, 1]
+    end
+
+    it "supports 'string': key literal" do
+      case {a: 0}
+      in {"a": 0}
+        true
+      end.should == true
+    end
+
+    it "does not support non-symbol keys" do
+      -> {
+        eval <<~RUBY
+          case {a: 1}
+          in {"a" => 1}
+          end
+        RUBY
+      }.should.raise(SyntaxError, /unexpected|expected a label as the key in the hash pattern/)
+    end
+
+    it "does not support string interpolation in keys" do
+      -> {
+        eval <<~'RUBY'
+          case {a: 1}
+          in {"#{x}": 1}
+          end
+        RUBY
+      }.should.raise(SyntaxError, /symbol literal with interpolation is not allowed|expected a label as the key in the hash pattern/)
+    end
+
+    it "raise SyntaxError when keys duplicate in pattern" do
+      -> {
+        eval <<~RUBY
+          case {a: 1}
+          in {a: 1, b: 2, a: 3}
+          end
+        RUBY
+      }.should.raise(SyntaxError, /duplicated key name/)
+    end
+
+    it "matches an object with #deconstruct_keys method which returns a Hash with equal keys and each value in Hash matches value in pattern" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*)
+        {a: 1}
+      end
+
+      case obj
+      in {a: 1}
+        true
+      end.should == true
+    end
+
+    it "calls #deconstruct_keys per pattern" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*)
+        ScratchPad << :deconstruct_keys
+        {a: 1}
+      end
+
+      case obj
+      in {b: 1}
+        false
+      in {a: 1}
+        true
+      end.should == true
+
+      ScratchPad.recorded.should == [:deconstruct_keys, :deconstruct_keys]
+    end
+
+    it "does not match object if Constant === object returns false" do
+      case {a: 1}
+      in String[a: 1]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "checks Constant === object before calling #deconstruct_keys" do
+      c1 = Class.new
+      obj = c1.new
+      obj.should_not_receive(:deconstruct_keys)
+
+      case obj
+      in String(a: 1)
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "does not match object without #deconstruct_keys method" do
+      obj = Object.new
+      obj.should_receive(:respond_to?).with(:deconstruct_keys)
+
+      case obj
+      in Object[a: 1]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "does not match object if #deconstruct_keys method does not return Hash" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*)
+        ""
+      end
+
+      -> {
+        case obj
+        in Object[a: 1]
+        end
+      }.should.raise(TypeError, /deconstruct_keys must return Hash/)
+    end
+
+    it "does not match object if #deconstruct_keys method returns Hash with non-symbol keys" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*)
+        {"a" => 1}
+      end
+
+      case obj
+      in Object[a: 1]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "does not match object if elements of Hash returned by #deconstruct_keys method does not match values in pattern" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*)
+        {a: 1}
+      end
+
+      case obj
+      in Object[a: 2]
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "passes keys specified in pattern as arguments to #deconstruct_keys method" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*args)
+        ScratchPad << args
+        {a: 1, b: 2, c: 3}
+      end
+
+      case obj
+      in Object[a: 1, b: 2, c: 3]
+      end
+
+      ScratchPad.recorded.sort.should == [[[:a, :b, :c]]]
+    end
+
+    it "passes keys specified in pattern to #deconstruct_keys method if pattern contains double splat operator **" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*args)
+        ScratchPad << args
+        {a: 1, b: 2, c: 3}
+      end
+
+      case obj
+      in Object[a: 1, b: 2, **]
+      end
+
+      ScratchPad.recorded.sort.should == [[[:a, :b]]]
+    end
+
+    it "passes nil to #deconstruct_keys method if pattern contains double splat operator **rest" do
+      obj = Object.new
+
+      def obj.deconstruct_keys(*args)
+        ScratchPad << args
+        {a: 1, b: 2}
+      end
+
+      case obj
+      in Object[a: 1, **rest]
+      end
+
+      ScratchPad.recorded.should == [[nil]]
+    end
+
+    it "binds variables" do
+      case {a: 0, b: 1, c: 2}
+      in {a: x, b: y, c: z}
+        [x, y, z]
+      end.should == [0, 1, 2]
+    end
+
+    it "supports double splat operator **rest" do
+      case {a: 0, b: 1, c: 2}
+      in {a: 0, **rest}
+        rest
+      end.should == {b: 1, c: 2}
+    end
+
+    it "treats **nil like there should not be any other keys in a matched Hash" do
+      case {a: 1, b: 2}
+      in {a: 1, b: 2, **nil}
+        true
+      end.should == true
+
+      case {a: 1, b: 2}
+      in {a: 1, **nil}
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "can match partially" do
+      case {a: 1, b: 2}
+      in {a: 1}
+        true
+      end.should == true
+    end
+
+    it "matches {} with {}" do
+      case {}
+      in {}
+        true
+      end.should == true
+    end
+
+    it "in {} only matches empty hashes" do
+      case {a: 1}
+      in {}
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "in {**nil} only matches empty hashes" do
+      case {}
+      in {**nil}
+        true
+      else
+        false
+      end.should == true
+
+      case {a: 1}
+      in {**nil}
+        true
+      else
+        false
+      end.should == false
+    end
+
+    it "matches anything with **" do
+      case {a: 1}
+      in **;
+        true
+      end.should == true
+    end
+
+    it "can be used as a nested pattern" do
+      case {a: {a: 1, b: 1}, b: {a: 1, b: 2}}
+      in {a: {a: 0}}
+        false
+      in {a: {a: 1}, b: {b: 1}}
+        false
+      in {a: {a: 1}, b: {b: 2} }
+        true
+      end.should == true
+
+      case [{a: 1, b: [1]}, {a: 1, c: ["2"]}]
+      in [{a:, c:}, ]
+        false
+      in [{a: 1, b:}, {a: 1, c: [Integer]}]
+        false
+      in [_, {a: 1, c: [String]}]
+        true
+      end.should == true
+    end
+  end
+
+  describe "refinements" do
+    it "are used for #deconstruct" do
+      refinery = Module.new do
+        refine Array do
+          def deconstruct
+            [0]
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinery
+
+        result =
+          case []
+          in [0]
+            true
+          end
+      end
+
+      result.should == true
+    end
+
+    it "are used for #deconstruct_keys" do
+      refinery = Module.new do
+        refine Hash do
+          def deconstruct_keys(_)
+            {a: 0}
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinery
+
+        result =
+          case {}
+          in a: 0
+            true
+          end
+      end
+
+      result.should == true
+    end
+
+    it "are used for #=== in constant pattern" do
+      refinery = Module.new do
+        refine Array.singleton_class do
+          def ===(obj)
+            obj.is_a?(Hash)
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinery
+
+        result =
+          case {}
+          in Array
+            true
+          end
+      end
+
+      result.should == true
+    end
+  end
+
+  describe "Ruby 3.1 improvements" do
+    it "can omit parentheses in one line pattern matching" do
+      [1, 2] => a, b
+      [a, b].should == [1, 2]
+
+      {a: 1} => a:
+      a.should == 1
+    end
+
+    it "supports pinning instance variables" do
+      @a = /a/
+      case 'abc'
+      in ^@a
+        true
+      end.should == true
+    end
+
+    it "supports pinning class variables" do
+      result = nil
+      Module.new do
+        # avoid "class variable access from toplevel" runtime error with #module_eval
+        result = module_eval(<<~RUBY)
+          @@a = 0..10
+
+          case 2
+          in ^@@a
+            true
+          end
+        RUBY
+      end
+
+      result.should == true
+    end
+
+    it "supports pinning global variables" do
+      $a = /a/
+      case 'abc'
+      in ^$a
+        true
+      end.should == true
+    end
+
+    it "supports pinning expressions" do
+      case 'abc'
+      in ^(/a/)
+        true
+      end.should == true
+
+      case 0
+      in ^(0 + 0)
+        true
+      end.should == true
+    end
+
+    it "supports pinning expressions in array pattern" do
+      case [3]
+      in [^(1 + 2)]
+        true
+      end.should == true
+    end
+
+    it "supports pinning expressions in hash pattern" do
+      case {name: '2.6', released_at: Time.new(2018, 12, 25)}
+      in {released_at: ^(Time.new(2010)..Time.new(2020))}
+        true
+      end.should == true
+    end
+  end
+
+  describe "value in pattern" do
+    it "returns true if the pattern matches" do
+      (1 in 1).should == true
+
+      (1 in Integer).should == true
+
+      e = nil
+      ([1, 2] in [1, e]).should == true
+      e.should == 2
+
+      k = nil
+      ({k: 1} in {k:}).should == true
+      k.should == 1
+    end
+
+    it "returns false if the pattern does not match" do
+      (1 in 2).should == false
+
+      (1 in Float).should == false
+
+      ([1, 2] in [2, e]).should == false
+
+      ({k: 1} in {k: 2}).should == false
+    end
+  end
+end
diff --git a/spec/ruby/language/precedence_spec.rb b/spec/ruby/language/precedence_spec.rb
index 5a3c2861ce..edb990525e 100644
--- a/spec/ruby/language/precedence_spec.rb
+++ b/spec/ruby/language/precedence_spec.rb
@@ -14,46 +14,44 @@ require_relative 'fixtures/precedence'
 # the level below (as well as showing associativity within
 # the precedence level).
 
-=begin
-Excerpted from 'Programming Ruby: The Pragmatic Programmer's Guide'
-Second Edition by Dave Thomas, Chad Fowler, and Andy Hunt, page 324
-
-Table 22.4. Ruby operators (high to low precedence)
-Method   Operator                  Description
------------------------------------------------------------------------
-         :: .
- x*      [ ] [ ]=                  Element reference, element set
- x       **                        Exponentiation
- x       ! ~ + -                   Not, complement, unary plus and minus
-                                   (method names for the last two are +@ and -@)
- x       * / %                     Multiply, divide, and modulo
- x       + -                       Plus and minus
- x       >> <<                     Right and left shift
- x       &                         “And” (bitwise for integers)
- x       ^ |                       Exclusive “or” and regular “or” (bitwise for integers)
- x       <= < > >=                 Comparison operators
- x       <=> == === != =~ !~       Equality and pattern match operators (!=
-                                   and !~ may not be defined as methods)
-         &&                        Logical “and”
-         ||                        Logical “or”
-         .. ...                    Range (inclusive and exclusive)
-         ? :                       Ternary if-then-else
-         = %= /= -= += |= &=       Assignment
-         >>= <<= *= &&= ||= **=
-         defined?                  Check if symbol defined
-         not                       Logical negation
-         or and                    Logical composition
-         if unless while until     Expression modifiers
-         begin/end                 Block expression
------------------------------------------------------------------------
-
-* Operators marked with 'x' in the Method column are implemented as methods
-and can be overridden (except != and !~ as noted). (But see the specs
-below for implementations that define != and !~ as methods.)
-
-** These are not included in the excerpted table but are shown here for
-completeness.
-=end
+# Excerpted from 'Programming Ruby: The Pragmatic Programmer's Guide'
+# Second Edition by Dave Thomas, Chad Fowler, and Andy Hunt, page 324
+#
+# Table 22.4. Ruby operators (high to low precedence)
+# Method   Operator                  Description
+# -----------------------------------------------------------------------
+#          :: .
+#  x*      [ ] [ ]=                  Element reference, element set
+#  x       **                        Exponentiation
+#  x       ! ~ + -                   Not, complement, unary plus and minus
+#                                    (method names for the last two are +@ and -@)
+#  x       * / %                     Multiply, divide, and modulo
+#  x       + -                       Plus and minus
+#  x       >> <<                     Right and left shift
+#  x       &                         “And” (bitwise for integers)
+#  x       ^ |                       Exclusive “or” and regular “or” (bitwise for integers)
+#  x       <= < > >=                 Comparison operators
+#  x       <=> == === != =~ !~       Equality and pattern match operators (!=
+#                                    and !~ may not be defined as methods)
+#          &&                        Logical “and”
+#          ||                        Logical “or”
+#          .. ...                    Range (inclusive and exclusive)
+#          ? :                       Ternary if-then-else
+#          = %= /= -= += |= &=       Assignment
+#          >>= <<= *= &&= ||= **=
+#          defined?                  Check if symbol defined
+#          not                       Logical negation
+#          or and                    Logical composition
+#          if unless while until     Expression modifiers
+#          begin/end                 Block expression
+# -----------------------------------------------------------------------
+#
+# * Operators marked with 'x' in the Method column are implemented as methods
+# and can be overridden (except != and !~ as noted). (But see the specs
+# below for implementations that define != and !~ as methods.)
+#
+# ** These are not included in the excerpted table but are shown here for
+# completeness.
 
 # -----------------------------------------------------------------------
 # It seems that this table is not correct anymore
@@ -253,12 +251,12 @@ describe "Operators" do
   end
 
   it "<=> == === != =~ !~ are non-associative" do
-    -> { eval("1 <=> 2 <=> 3")  }.should raise_error(SyntaxError)
-    -> { eval("1 == 2 == 3")  }.should raise_error(SyntaxError)
-    -> { eval("1 === 2 === 3")  }.should raise_error(SyntaxError)
-    -> { eval("1 != 2 != 3")  }.should raise_error(SyntaxError)
-    -> { eval("1 =~ 2 =~ 3")  }.should raise_error(SyntaxError)
-    -> { eval("1 !~ 2 !~ 3")  }.should raise_error(SyntaxError)
+    -> { eval("1 <=> 2 <=> 3")  }.should.raise(SyntaxError)
+    -> { eval("1 == 2 == 3")  }.should.raise(SyntaxError)
+    -> { eval("1 === 2 === 3")  }.should.raise(SyntaxError)
+    -> { eval("1 != 2 != 3")  }.should.raise(SyntaxError)
+    -> { eval("1 =~ 2 =~ 3")  }.should.raise(SyntaxError)
+    -> { eval("1 !~ 2 !~ 3")  }.should.raise(SyntaxError)
   end
 
   it "<=> == === != =~ !~ have higher precedence than &&" do
@@ -292,18 +290,18 @@ describe "Operators" do
   end
 
   it ".. ... are non-associative" do
-    -> { eval("1..2..3")  }.should raise_error(SyntaxError)
-    -> { eval("1...2...3")  }.should raise_error(SyntaxError)
-  end
-
- it ".. ... have higher precedence than ? :" do
-   # Use variables to avoid warnings
-   from = 1
-   to = 2
-   # These are flip-flop, not Range instances
-   (from..to ? 3 : 4).should == 3
-   (from...to ? 3 : 4).should == 3
- end
+    -> { eval("1..2..3")  }.should.raise(SyntaxError)
+    -> { eval("1...2...3")  }.should.raise(SyntaxError)
+  end
+
+  it ".. ... have higher precedence than ? :" do
+    # Use variables to avoid warnings
+    from = 1
+    to = 2
+    # These are flip-flop, not Range instances
+    (from..to ? 3 : 4).should == 3
+    (from...to ? 3 : 4).should == 3
+  end
 
   it "? : is right-associative" do
     (true ? 2 : 3 ? 4 : 5).should == 2
diff --git a/spec/ruby/language/predefined_spec.rb b/spec/ruby/language/predefined_spec.rb
index 90ea8c6bb1..d57b924bcf 100644
--- a/spec/ruby/language/predefined_spec.rb
+++ b/spec/ruby/language/predefined_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../spec_helper'
+require_relative '../core/exception/shared/set_backtrace'
 require 'stringio'
 
 # The following tables are excerpted from Programming Ruby: The Pragmatic Programmer's Guide'
@@ -7,56 +8,52 @@ require 'stringio'
 # Entries marked [r/o] are read-only and an error will be raised of the program attempts to
 # modify them. Entries marked [thread] are thread local.
 
-=begin
-Exception Information
----------------------------------------------------------------------------------------------------
-
-$!               Exception       The exception object passed to raise. [thread]
-$@               Array           The stack backtrace generated by the last exception. [thread]
-=end
-
-=begin
-Pattern Matching Variables
----------------------------------------------------------------------------------------------------
-
-These variables are set to nil after an unsuccessful pattern match.
-
-$&               String          The string matched (following a successful pattern match). This variable is
-                                 local to the current scope. [r/o, thread]
-$+               String          The contents of the highest-numbered group matched following a successful
-                                 pattern match. Thus, in "cat" =~/(c|a)(t|z)/, $+ will be set to “t”. This
-                                 variable is local to the current scope. [r/o, thread]
-$`               String          The string preceding the match in a successful pattern match. This variable
-                                 is local to the current scope. [r/o, thread]
-$'               String          The string following the match in a successful pattern match. This variable
-                                 is local to the current scope. [r/o, thread]
-$1 to $<N>       String          The contents of successive groups matched in a successful pattern match. In
-                                 "cat" =~/(c|a)(t|z)/, $1 will be set to “a” and $2 to “t”. This variable
-                                 is local to the current scope. [r/o, thread]
-$~               MatchData       An object that encapsulates the results of a successful pattern match. The
-                                 variables $&, $`, $', and $1 to $<N> are all derived from $~. Assigning to $~
-                                 changes the values of these derived variables. This variable is local to the
-                                 current scope. [thread]
-=end
+# Exception Information
+# ---------------------------------------------------------------------------------------------------
+#
+# $!               Exception       The exception object passed to raise. [thread]
+# $@               Array           The stack backtrace generated by the last exception. [thread]
+
+# Pattern Matching Variables
+# ---------------------------------------------------------------------------------------------------
+#
+# These variables are set to nil after an unsuccessful pattern match.
+#
+# $&               String          The string matched (following a successful pattern match). This variable is
+#                                  local to the current scope. [r/o, thread]
+# $+               String          The contents of the highest-numbered group matched following a successful
+#                                  pattern match. Thus, in "cat" =~/(c|a)(t|z)/, $+ will be set to “t”. This
+#                                  variable is local to the current scope. [r/o, thread]
+# $`               String          The string preceding the match in a successful pattern match. This variable
+#                                  is local to the current scope. [r/o, thread]
+# $'               String          The string following the match in a successful pattern match. This variable
+#                                  is local to the current scope. [r/o, thread]
+# $1 to $<N>       String          The contents of successive groups matched in a successful pattern match. In
+#                                  "cat" =~/(c|a)(t|z)/, $1 will be set to “a” and $2 to “t”. This variable
+#                                  is local to the current scope. [r/o, thread]
+# $~               MatchData       An object that encapsulates the results of a successful pattern match. The
+#                                  variables $&, $`, $', and $1 to $<N> are all derived from $~. Assigning to $~
+#                                  changes the values of these derived variables. This variable is local to the
+#                                  current scope. [thread]
 
 
 describe "Predefined global $~" do
   it "is set to contain the MatchData object of the last match if successful" do
     md = /foo/.match 'foo'
-    $~.should be_kind_of(MatchData)
-    $~.should equal md
+    $~.should.is_a?(MatchData)
+    $~.should.equal? md
 
     /bar/ =~ 'bar'
-    $~.should be_kind_of(MatchData)
-    $~.should_not equal md
+    $~.should.is_a?(MatchData)
+    $~.should_not.equal? md
   end
 
   it "is set to nil if the last match was unsuccessful" do
     /foo/ =~ 'foo'
-    $~.nil?.should == false
+    $~.should_not.nil?
 
     /foo/ =~ 'bar'
-    $~.nil?.should == true
+    $~.should.nil?
   end
 
   it "is set at the method-scoped level rather than block-scoped" do
@@ -75,7 +72,7 @@ describe "Predefined global $~" do
     match2.should_not == nil
     $~.should == match2
 
-    eval 'match3 = /baz/.match("baz")'
+    match3 = /baz/.match("baz")
 
     match3.should_not == nil
     $~.should == match3
@@ -90,10 +87,10 @@ describe "Predefined global $~" do
     $~ = nil
     $~.should == nil
     $~ = /foo/.match("foo")
-    $~.should be_an_instance_of(MatchData)
+    $~.should.instance_of?(MatchData)
 
-    -> { $~ = Object.new }.should raise_error(TypeError)
-    -> { $~ = 1 }.should raise_error(TypeError)
+    -> { $~ = Object.new }.should.raise(TypeError, 'wrong argument type Object (expected MatchData)')
+    -> { $~ = 1 }.should.raise(TypeError, 'wrong argument type Integer (expected MatchData)')
   end
 
   it "changes the value of derived capture globals when assigned" do
@@ -137,8 +134,21 @@ describe "Predefined global $&" do
   end
 
   it "sets the encoding to the encoding of the source String" do
-    "abc".force_encoding(Encoding::EUC_JP) =~ /b/
-    $&.encoding.should equal(Encoding::EUC_JP)
+    "abc".dup.force_encoding(Encoding::EUC_JP) =~ /b/
+    $&.encoding.should.equal?(Encoding::EUC_JP)
+  end
+
+  it "is read-only" do
+    -> {
+      eval %q{$& = ""}
+    }.should.raise(SyntaxError, /Can't set variable \$&/)
+  end
+
+  it "is read-only when aliased" do
+    alias $predefined_spec_ampersand $&
+    -> {
+      $predefined_spec_ampersand = ""
+    }.should.raise(NameError, '$predefined_spec_ampersand is a read-only variable')
   end
 end
 
@@ -150,13 +160,26 @@ describe "Predefined global $`" do
   end
 
   it "sets the encoding to the encoding of the source String" do
-    "abc".force_encoding(Encoding::EUC_JP) =~ /b/
-    $`.encoding.should equal(Encoding::EUC_JP)
+    "abc".dup.force_encoding(Encoding::EUC_JP) =~ /b/
+    $`.encoding.should.equal?(Encoding::EUC_JP)
   end
 
   it "sets an empty result to the encoding of the source String" do
-    "abc".force_encoding(Encoding::ISO_8859_1) =~ /a/
-    $`.encoding.should equal(Encoding::ISO_8859_1)
+    "abc".dup.force_encoding(Encoding::ISO_8859_1) =~ /a/
+    $`.encoding.should.equal?(Encoding::ISO_8859_1)
+  end
+
+  it "is read-only" do
+    -> {
+      eval %q{$` = ""}
+    }.should.raise(SyntaxError, /Can't set variable \$`/)
+  end
+
+  it "is read-only when aliased" do
+    alias $predefined_spec_backquote $`
+    -> {
+      $predefined_spec_backquote = ""
+    }.should.raise(NameError, '$predefined_spec_backquote is a read-only variable')
   end
 end
 
@@ -168,13 +191,26 @@ describe "Predefined global $'" do
   end
 
   it "sets the encoding to the encoding of the source String" do
-    "abc".force_encoding(Encoding::EUC_JP) =~ /b/
-    $'.encoding.should equal(Encoding::EUC_JP)
+    "abc".dup.force_encoding(Encoding::EUC_JP) =~ /b/
+    $'.encoding.should.equal?(Encoding::EUC_JP)
   end
 
   it "sets an empty result to the encoding of the source String" do
-    "abc".force_encoding(Encoding::ISO_8859_1) =~ /c/
-    $'.encoding.should equal(Encoding::ISO_8859_1)
+    "abc".dup.force_encoding(Encoding::ISO_8859_1) =~ /c/
+    $'.encoding.should.equal?(Encoding::ISO_8859_1)
+  end
+
+  it "is read-only" do
+    -> {
+      eval %q{$' = ""}
+    }.should.raise(SyntaxError, /Can't set variable \$'/)
+  end
+
+  it "is read-only when aliased" do
+    alias $predefined_spec_single_quote $'
+    -> {
+      $predefined_spec_single_quote = ""
+    }.should.raise(NameError, '$predefined_spec_single_quote is a read-only variable')
   end
 end
 
@@ -191,8 +227,21 @@ describe "Predefined global $+" do
   end
 
   it "sets the encoding to the encoding of the source String" do
-    "abc".force_encoding(Encoding::EUC_JP) =~ /(b)/
-    $+.encoding.should equal(Encoding::EUC_JP)
+    "abc".dup.force_encoding(Encoding::EUC_JP) =~ /(b)/
+    $+.encoding.should.equal?(Encoding::EUC_JP)
+  end
+
+  it "is read-only" do
+    -> {
+      eval %q{$+ = ""}
+    }.should.raise(SyntaxError, /Can't set variable \$\+/)
+  end
+
+  it "is read-only when aliased" do
+    alias $predefined_spec_plus $+
+    -> {
+      $predefined_spec_plus = ""
+    }.should.raise(NameError, '$predefined_spec_plus is a read-only variable')
   end
 end
 
@@ -218,8 +267,8 @@ describe "Predefined globals $1..N" do
   end
 
   it "sets the encoding to the encoding of the source String" do
-    "abc".force_encoding(Encoding::EUC_JP) =~ /(b)/
-    $1.encoding.should equal(Encoding::EUC_JP)
+    "abc".dup.force_encoding(Encoding::EUC_JP) =~ /(b)/
+    $1.encoding.should.equal?(Encoding::EUC_JP)
   end
 end
 
@@ -233,20 +282,36 @@ describe "Predefined global $stdout" do
   end
 
   it "raises TypeError error if assigned to nil" do
-    -> { $stdout = nil }.should raise_error(TypeError)
+    -> { $stdout = nil }.should.raise(TypeError, '$stdout must have write method, NilClass given')
   end
 
   it "raises TypeError error if assigned to object that doesn't respond to #write" do
     obj = mock('object')
-    -> { $stdout = obj }.should raise_error(TypeError)
+    -> { $stdout = obj }.should.raise(TypeError)
 
     obj.stub!(:write)
     $stdout = obj
-    $stdout.should equal(obj)
+    $stdout.should.equal?(obj)
   end
 end
 
 describe "Predefined global $!" do
+  it "is Fiber-local" do
+    Fiber.new do
+      raise "hi"
+    rescue
+      Fiber.yield
+    end.resume
+
+    $!.should == nil
+  end
+
+  it "is read-only" do
+    -> {
+      $! = []
+    }.should.raise(NameError, '$! is a read-only variable')
+  end
+
   # See http://jira.codehaus.org/browse/JRUBY-5550
   it "remains nil after a failed core class \"checked\" coercion against a class that defines method_missing" do
     $!.should == nil
@@ -398,6 +463,22 @@ describe "Predefined global $!" do
       $!.should == nil
     end
 
+    it "should be cleared when an exception is rescued even when a non-local return from block" do
+      def foo
+        [ 1 ].each do
+          begin
+            raise StandardError.new('err')
+          rescue => e
+            $!.should == e
+            return
+          end
+        end
+      end
+
+      foo
+      $!.should == nil
+    end
+
     it "should not be cleared when an exception is not rescued" do
       e = StandardError.new
       begin
@@ -490,44 +571,112 @@ describe "Predefined global $!" do
   end
 end
 
-=begin
-Input/Output Variables
----------------------------------------------------------------------------------------------------
-
-$/               String          The input record separator (newline by default). This is the value that rou-
-                                 tines such as Kernel#gets use to determine record boundaries. If set to
-                                 nil, gets will read the entire file.
-$-0              String          Synonym for $/.
-$\               String          The string appended to the output of every call to methods such as
-                                 Kernel#print and IO#write. The default value is nil.
-$,               String          The separator string output between the parameters to methods such as
-                                 Kernel#print and Array#join. Defaults to nil, which adds no text.
-$.               Fixnum          The number of the last line read from the current input file.
-$;               String          The default separator pattern used by String#split. May be set from the
-                                 command line using the -F flag.
-$<               Object          An object that provides access to the concatenation of the contents of all
-                                 the files given as command-line arguments or $stdin (in the case where
-                                 there are no arguments). $< supports methods similar to a File object:
-                                 binmode, close, closed?, each, each_byte, each_line, eof, eof?,
-                                 file, filename, fileno, getc, gets, lineno, lineno=, path, pos, pos=,
-                                 read, readchar, readline, readlines, rewind, seek, skip, tell, to_a,
-                                 to_i, to_io, to_s, along with the methods in Enumerable. The method
-                                 file returns a File object for the file currently being read. This may change
-                                 as $< reads through the files on the command line. [r/o]
-$>               IO              The destination of output for Kernel#print and Kernel#printf. The
-                                 default value is $stdout.
-$_               String          The last line read by Kernel#gets or Kernel#readline. Many string-
-                                 related functions in the Kernel module operate on $_ by default. The vari-
-                                 able is local to the current scope. [thread]
-$-F              String          Synonym for $;.
-$stderr          IO              The current standard error output.
-$stdin           IO              The current standard input.
-$stdout          IO              The current standard output. Assignment to $stdout is deprecated: use
-                                 $stdout.reopen instead.
-=end
+describe "Predefined global $@" do
+  it "is Fiber-local" do
+    Fiber.new do
+      raise "hi"
+    rescue
+      Fiber.yield
+    end.resume
+
+    $@.should == nil
+  end
+
+  it "is set to a backtrace of a rescued exception" do
+    begin
+      raise
+    rescue
+      $@.should.instance_of?(Array)
+      $@.should == $!.backtrace
+    end
+  end
+
+  it "is cleared when an exception is rescued" do
+    begin
+      raise
+    rescue
+    end
+
+    $@.should == nil
+  end
+
+  it "is not set when there is no current exception" do
+    $@.should == nil
+  end
+
+  it "is set to a backtrace of a rescued exception" do
+    begin
+      raise
+    rescue
+      $@.should.instance_of?(Array)
+      $@.should == $!.backtrace
+    end
+  end
+
+  it "is not read-only" do
+    begin
+      raise
+    rescue
+      $@ = []
+      $@.should == []
+    end
+  end
+
+  it_behaves_like :exception_set_backtrace, -> backtrace {
+    exception = nil
+    begin
+      raise
+    rescue
+      $@ = backtrace
+      exception = $!
+    end
+    exception
+  }
+
+  it "cannot be assigned when there is no a rescued exception" do
+    -> {
+      $@ = []
+    }.should.raise(ArgumentError, '$! not set')
+  end
+end
+
+# Input/Output Variables
+# ---------------------------------------------------------------------------------------------------
+#
+# $/               String          The input record separator (newline by default). This is the value that rou-
+#                                  tines such as Kernel#gets use to determine record boundaries. If set to
+#                                  nil, gets will read the entire file.
+# $-0              String          Synonym for $/.
+# $\               String          The string appended to the output of every call to methods such as
+#                                  Kernel#print and IO#write. The default value is nil.
+# $,               String          The separator string output between the parameters to methods such as
+#                                  Kernel#print and Array#join. Defaults to nil, which adds no text.
+# $.               Integer          The number of the last line read from the current input file.
+# $;               String          The default separator pattern used by String#split. May be set from the
+#                                  command line using the -F flag.
+# $<               Object          An object that provides access to the concatenation of the contents of all
+#                                  the files given as command-line arguments or $stdin (in the case where
+#                                  there are no arguments). $< supports methods similar to a File object:
+#                                  binmode, close, closed?, each, each_byte, each_line, eof, eof?,
+#                                  file, filename, fileno, getc, gets, lineno, lineno=, path, pos, pos=,
+#                                  read, readchar, readline, readlines, rewind, seek, skip, tell, to_a,
+#                                  to_i, to_io, to_s, along with the methods in Enumerable. The method
+#                                  file returns a File object for the file currently being read. This may change
+#                                  as $< reads through the files on the command line. [r/o]
+# $>               IO              The destination of output for Kernel#print and Kernel#printf. The
+#                                  default value is $stdout.
+# $_               String          The last line read by Kernel#gets or Kernel#readline. Many string-
+#                                  related functions in the Kernel module operate on $_ by default. The vari-
+#                                  able is local to the current scope. [thread]
+# $-F              String          Synonym for $;.
+# $stderr          IO              The current standard error output.
+# $stdin           IO              The current standard input.
+# $stdout          IO              The current standard output. Assignment to $stdout is deprecated: use
+#                                  $stdout.reopen instead.
 
 describe "Predefined global $/" do
   before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
     @dollar_slash = $/
     @dollar_dash_zero = $-0
   end
@@ -535,47 +684,80 @@ describe "Predefined global $/" do
   after :each do
     $/ = @dollar_slash
     $-0 = @dollar_dash_zero
+    $VERBOSE = @verbose
   end
 
-  it "can be assigned a String" do
-    str = "abc"
-    $/ = str
-    $/.should equal(str)
+  ruby_version_is ""..."4.0" do
+    it "can be assigned a String" do
+      str = +"abc"
+      $/ = str
+      $/.should.equal?(str)
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "makes a new frozen String from the assigned String" do
+      string_subclass = Class.new(String)
+      str = string_subclass.new("abc")
+      str.instance_variable_set(:@ivar, 1)
+      $/ = str
+      $/.should.frozen?
+      $/.should.instance_of?(String)
+      $/.should_not.instance_variable_defined?(:@ivar)
+      $/.should == str
+    end
+
+    it "makes a new frozen String if it's not frozen" do
+      str = +"abc"
+      $/ = str
+      $/.should.frozen?
+      $/.should == str
+    end
+
+    it "assigns the given String if it's frozen and has no instance variables" do
+      str = "abc".freeze
+      $/ = str
+      $/.should.equal?(str)
+    end
   end
 
   it "can be assigned nil" do
     $/ = nil
-    $/.should be_nil
+    $/.should == nil
   end
 
   it "returns the value assigned" do
     ($/ = "xyz").should == "xyz"
   end
 
-
   it "changes $-0" do
     $/ = "xyz"
-    $-0.should equal($/)
+    $-0.should.equal?($/)
   end
 
   it "does not call #to_str to convert the object to a String" do
     obj = mock("$/ value")
     obj.should_not_receive(:to_str)
 
-    -> { $/ = obj }.should raise_error(TypeError)
+    -> { $/ = obj }.should.raise(TypeError, 'value of $/ must be String')
   end
 
-  it "raises a TypeError if assigned a Fixnum" do
-    -> { $/ = 1 }.should raise_error(TypeError)
+  it "raises a TypeError if assigned an Integer" do
+    -> { $/ = 1 }.should.raise(TypeError, 'value of $/ must be String')
   end
 
   it "raises a TypeError if assigned a boolean" do
-    -> { $/ = true }.should raise_error(TypeError)
+    -> { $/ = true }.should.raise(TypeError, 'value of $/ must be String')
+  end
+
+  it "warns if assigned non-nil" do
+    -> { $/ = "_" }.should complain(/warning: (?:non-nil )?[`']\$\/' is deprecated/)
   end
 end
 
 describe "Predefined global $-0" do
   before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
     @dollar_slash = $/
     @dollar_dash_zero = $-0
   end
@@ -583,17 +765,46 @@ describe "Predefined global $-0" do
   after :each do
     $/ = @dollar_slash
     $-0 = @dollar_dash_zero
+    $VERBOSE = @verbose
   end
 
-  it "can be assigned a String" do
-    str = "abc"
-    $-0 = str
-    $-0.should equal(str)
+  ruby_version_is ""..."4.0" do
+    it "can be assigned a String" do
+      str = +"abc"
+      $-0 = str
+      $-0.should.equal?(str)
+    end
+  end
+
+  ruby_version_is "4.0" do
+    it "makes a new frozen String from the assigned String" do
+      string_subclass = Class.new(String)
+      str = string_subclass.new("abc")
+      str.instance_variable_set(:@ivar, 1)
+      $-0 = str
+      $-0.should.frozen?
+      $-0.should.instance_of?(String)
+      $-0.should_not.instance_variable_defined?(:@ivar)
+      $-0.should == str
+    end
+
+    it "makes a new frozen String if it's not frozen" do
+      str = +"abc"
+      $-0 = str
+      $-0.should.frozen?
+      $-0.should == str
+    end
+
+    it "assigns the given String if it's frozen and has no instance variables" do
+      str = "abc".freeze
+      $-0 = str
+      $-0.should.equal?(str)
+    end
   end
 
   it "can be assigned nil" do
     $-0 = nil
-    $-0.should be_nil
+    $-0.should == nil
   end
 
   it "returns the value assigned" do
@@ -602,22 +813,69 @@ describe "Predefined global $-0" do
 
   it "changes $/" do
     $-0 = "xyz"
-    $/.should equal($-0)
+    $/.should.equal?($-0)
   end
 
   it "does not call #to_str to convert the object to a String" do
     obj = mock("$-0 value")
     obj.should_not_receive(:to_str)
 
-    -> { $-0 = obj }.should raise_error(TypeError)
+    -> { $-0 = obj }.should.raise(TypeError, 'value of $-0 must be String')
   end
 
-  it "raises a TypeError if assigned a Fixnum" do
-    -> { $-0 = 1 }.should raise_error(TypeError)
+  it "raises a TypeError if assigned an Integer" do
+    -> { $-0 = 1 }.should.raise(TypeError, 'value of $-0 must be String')
   end
 
   it "raises a TypeError if assigned a boolean" do
-    -> { $-0 = true }.should raise_error(TypeError)
+    -> { $-0 = true }.should.raise(TypeError, 'value of $-0 must be String')
+  end
+
+  it "warns if assigned non-nil" do
+    -> { $-0 = "_" }.should complain(/warning: (?:non-nil )?[`']\$-0' is deprecated/)
+  end
+end
+
+describe "Predefined global $\\" do
+  before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
+    @dollar_backslash = $\
+  end
+
+  after :each do
+    $\ = @dollar_backslash
+    $VERBOSE = @verbose
+  end
+
+  it "can be assigned a String" do
+    str = "abc"
+    $\ = str
+    $\.should.equal?(str)
+  end
+
+  it "can be assigned nil" do
+    $\ = nil
+    $\.should == nil
+  end
+
+  it "returns the value assigned" do
+    ($\ = "xyz").should == "xyz"
+  end
+
+  it "does not call #to_str to convert the object to a String" do
+    obj = mock("$\\ value")
+    obj.should_not_receive(:to_str)
+
+    -> { $\ = obj }.should.raise(TypeError, 'value of $\ must be String')
+  end
+
+  it "raises a TypeError if assigned not String" do
+    -> { $\ = 1 }.should.raise(TypeError, 'value of $\ must be String')
+    -> { $\ = true }.should.raise(TypeError, 'value of $\ must be String')
+  end
+
+  it "warns if assigned non-nil" do
+    -> { $\ = "_" }.should complain(/warning: (?:non-nil )?[`']\$\\' is deprecated/)
   end
 end
 
@@ -627,11 +885,15 @@ describe "Predefined global $," do
   end
 
   it "defaults to nil" do
-    $,.should be_nil
+    $,.should == nil
   end
 
   it "raises TypeError if assigned a non-String" do
-    -> { $, = Object.new }.should raise_error(TypeError)
+    -> { $, = Object.new }.should.raise(TypeError, 'value of $, must be String')
+  end
+
+  it "warns if assigned non-nil" do
+    -> { $, = "_" }.should complain(/warning: (?:non-nil )?[`']\$,' is deprecated/)
   end
 end
 
@@ -658,7 +920,17 @@ describe "Predefined global $." do
     obj = mock("bad-value")
     obj.should_receive(:to_int).and_return('abc')
 
-    -> { $. = obj }.should raise_error(TypeError)
+    -> { $. = obj }.should.raise(TypeError)
+  end
+end
+
+describe "Predefined global $;" do
+  after :each do
+    $; = nil
+  end
+
+  it "warns if assigned non-nil" do
+    -> { $; = "_" }.should complain(/warning: (?:non-nil )?[`']\$;' is deprecated/)
   end
 end
 
@@ -692,7 +964,7 @@ describe "Predefined global $_" do
     match.should == "bar\n"
     $_.should == match
 
-    eval 'match = stdin.gets'
+    match = stdin.gets
 
     match.should == "baz\n"
     $_.should == match
@@ -713,7 +985,7 @@ describe "Predefined global $_" do
     end
 
     Thread.pass until running
-    $_.should be_nil
+    $_.should == nil
 
     thr.join
   end
@@ -731,56 +1003,52 @@ describe "Predefined global $_" do
   end
 end
 
-=begin
-Execution Environment Variables
----------------------------------------------------------------------------------------------------
-
-$0               String          The name of the top-level Ruby program being executed. Typically this will
-                                 be the program’s filename. On some operating systems, assigning to this
-                                 variable will change the name of the process reported (for example) by the
-                                 ps(1) command.
-$*               Array           An array of strings containing the command-line options from the invoca-
-                                 tion of the program. Options used by the Ruby interpreter will have been
-                                 removed. [r/o]
-$"               Array           An array containing the filenames of modules loaded by require. [r/o]
-$$               Fixnum          The process number of the program being executed. [r/o]
-$?               Process::Status The exit status of the last child process to terminate. [r/o, thread]
-$:               Array           An array of strings, where each string specifies a directory to be searched for
-                                 Ruby scripts and binary extensions used by the load and require methods.
-                                 The initial value is the value of the arguments passed via the -I command-
-                                 line option, followed by an installation-defined standard library location, fol-
-                                 lowed by the current directory (“.”). This variable may be set from within a
-                                 program to alter the default search path; typically, programs use $: << dir
-                                 to append dir to the path. [r/o]
-$-a              Object          True if the -a option is specified on the command line. [r/o]
-$-d              Object          Synonym for $DEBUG.
-$DEBUG           Object          Set to true if the -d command-line option is specified.
-__FILE__         String          The name of the current source file. [r/o]
-$F               Array           The array that receives the split input line if the -a command-line option is
-                                 used.
-$FILENAME        String          The name of the current input file. Equivalent to $<.filename. [r/o]
-$-i              String          If in-place edit mode is enabled (perhaps using the -i command-line
-                                 option), $-i holds the extension used when creating the backup file. If you
-                                 set a value into $-i, enables in-place edit mode.
-$-I              Array           Synonym for $:. [r/o]
-$-K              String          Sets the multibyte coding system for strings and regular expressions. Equiv-
-                                 alent to the -K command-line option.
-$-l              Object          Set to true if the -l option (which enables line-end processing) is present
-                                 on the command line. [r/o]
-__LINE__         String          The current line number in the source file. [r/o]
-$LOAD_PATH       Array           A synonym for $:. [r/o]
-$-p              Object          Set to true if the -p option (which puts an implicit while gets . . . end
-                                 loop around your program) is present on the command line. [r/o]
-$SAFE            Fixnum          The current safe level. This variable’s value may never be
-                                 reduced by assignment. [thread] (Not implemented in Rubinius)
-$VERBOSE         Object          Set to true if the -v, --version, -W, or -w option is specified on the com-
-                                 mand line. Set to false if no option, or -W1 is given. Set to nil if -W0
-                                 was specified. Setting this option to true causes the interpreter and some
-                                 library routines to report additional information. Setting to nil suppresses
-                                 all warnings (including the output of Kernel.warn).
-$-v              Object          Synonym for $VERBOSE.
-$-w              Object          Synonym for $VERBOSE.
-=end
+# Execution Environment Variables
+# ---------------------------------------------------------------------------------------------------
+#
+# $0               String          The name of the top-level Ruby program being executed. Typically this will
+#                                  be the program’s filename. On some operating systems, assigning to this
+#                                  variable will change the name of the process reported (for example) by the
+#                                  ps(1) command.
+# $*               Array           An array of strings containing the command-line options from the invoca-
+#                                  tion of the program. Options used by the Ruby interpreter will have been
+#                                  removed. [r/o]
+# $"               Array           An array containing the filenames of modules loaded by require. [r/o]
+# $$               Integer          The process number of the program being executed. [r/o]
+# $?               Process::Status The exit status of the last child process to terminate. [r/o, thread]
+# $:               Array           An array of strings, where each string specifies a directory to be searched for
+#                                  Ruby scripts and binary extensions used by the load and require methods.
+#                                  The initial value is the value of the arguments passed via the -I command-
+#                                  line option, followed by an installation-defined standard library location, fol-
+#                                  lowed by the current directory (“.”). This variable may be set from within a
+#                                  program to alter the default search path; typically, programs use $: << dir
+#                                  to append dir to the path. [r/o]
+# $-a              Object          True if the -a option is specified on the command line. [r/o]
+# $-d              Object          Synonym for $DEBUG.
+# $DEBUG           Object          Set to true if the -d command-line option is specified.
+# __FILE__         String          The name of the current source file. [r/o]
+# $F               Array           The array that receives the split input line if the -a command-line option is
+#                                  used.
+# $FILENAME        String          The name of the current input file. Equivalent to $<.filename. [r/o]
+# $-i              String          If in-place edit mode is enabled (perhaps using the -i command-line
+#                                  option), $-i holds the extension used when creating the backup file. If you
+#                                  set a value into $-i, enables in-place edit mode.
+# $-I              Array           Synonym for $:. [r/o]
+# $-K              String          Sets the multibyte coding system for strings and regular expressions. Equiv-
+#                                  alent to the -K command-line option.
+# $-l              Object          Set to true if the -l option (which enables line-end processing) is present
+#                                  on the command line. [r/o]
+# __LINE__         String          The current line number in the source file. [r/o]
+# $LOAD_PATH       Array           A synonym for $:. [r/o]
+# $-p              Object          Set to true if the -p option (which puts an implicit while gets . . . end
+#                                  loop around your program) is present on the command line. [r/o]
+# $VERBOSE         Object          Set to true if the -v, --version, -W, or -w option is specified on the com-
+#                                  mand line. Set to false if no option, or -W1 is given. Set to nil if -W0
+#                                  was specified. Setting this option to true causes the interpreter and some
+#                                  library routines to report additional information. Setting to nil suppresses
+#                                  all warnings (including the output of Kernel.warn).
+# $-v              Object          Synonym for $VERBOSE.
+# $-w              Object          Synonym for $VERBOSE.
 describe "Execution variable $:" do
   it "is initialized to an array of strings" do
     $:.is_a?(Array).should == true
@@ -788,7 +1056,7 @@ describe "Execution variable $:" do
   end
 
   it "does not include the current directory" do
-    $:.should_not include(".")
+    $:.should_not.include?(".")
   end
 
   it "is the same object as $LOAD_PATH and $-I" do
@@ -798,37 +1066,55 @@ describe "Execution variable $:" do
 
   it "can be changed via <<" do
     $: << "foo"
-    $:.should include("foo")
+    $:.should.include?("foo")
+  ensure
+    $:.delete("foo")
   end
 
   it "is read-only" do
     -> {
       $: = []
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$: is a read-only variable')
 
     -> {
       $LOAD_PATH = []
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$LOAD_PATH is a read-only variable')
 
     -> {
       $-I = []
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$-I is a read-only variable')
+  end
+
+  it "default $LOAD_PATH entries until sitelibdir included have @gem_prelude_index set" do
+    skip "no sense in ruby itself" if MSpecScript.instance_variable_defined?(:@testing_ruby)
+
+    if platform_is :windows
+      # See https://github.com/ruby/setup-ruby/pull/762#issuecomment-2917460440
+      $:.should.find { |e| File.realdirpath(e) == RbConfig::CONFIG['sitelibdir'] }
+      idx = $:.index { |e| File.realdirpath(e) == RbConfig::CONFIG['sitelibdir'] }
+    else
+      $:.should.include?(RbConfig::CONFIG['sitelibdir'])
+      idx = $:.index(RbConfig::CONFIG['sitelibdir'])
+    end
+
+    $:[idx..-1].all? { |p| p.instance_variable_defined?(:@gem_prelude_index) }.should == true
+    $:[0...idx].all? { |p| !p.instance_variable_defined?(:@gem_prelude_index) }.should == true
   end
 end
 
 describe "Global variable $\"" do
   it "is an alias for $LOADED_FEATURES" do
-    $".should equal $LOADED_FEATURES
+    $".should.equal? $LOADED_FEATURES
   end
 
   it "is read-only" do
     -> {
       $" = []
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$" is a read-only variable')
 
     -> {
       $LOADED_FEATURES = []
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$LOADED_FEATURES is a read-only variable')
   end
 end
 
@@ -836,7 +1122,7 @@ describe "Global variable $<" do
   it "is read-only" do
     -> {
       $< = nil
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$< is a read-only variable')
   end
 end
 
@@ -844,7 +1130,7 @@ describe "Global variable $FILENAME" do
   it "is read-only" do
     -> {
       $FILENAME = "-"
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$FILENAME is a read-only variable')
   end
 end
 
@@ -852,30 +1138,30 @@ describe "Global variable $?" do
   it "is read-only" do
     -> {
       $? = nil
-    }.should raise_error(NameError)
+    }.should.raise(NameError, '$? is a read-only variable')
   end
 
   it "is thread-local" do
     system(ruby_cmd('exit 0'))
-    Thread.new { $?.should be_nil }.join
+    Thread.new { $?.should == nil }.join
   end
 end
 
 describe "Global variable $-a" do
   it "is read-only" do
-    -> { $-a = true }.should raise_error(NameError)
+    -> { $-a = true }.should.raise(NameError, '$-a is a read-only variable')
   end
 end
 
 describe "Global variable $-l" do
   it "is read-only" do
-    -> { $-l = true }.should raise_error(NameError)
+    -> { $-l = true }.should.raise(NameError, '$-l is a read-only variable')
   end
 end
 
 describe "Global variable $-p" do
   it "is read-only" do
-    -> { $-p = true }.should raise_error(NameError)
+    -> { $-p = true }.should.raise(NameError, '$-p is a read-only variable')
   end
 end
 
@@ -890,28 +1176,40 @@ describe "Global variable $-d" do
 
   it "is an alias of $DEBUG" do
     $DEBUG = true
-    $-d.should be_true
+    $-d.should == true
     $-d = false
-    $DEBUG.should be_false
+    $DEBUG.should == false
   end
 end
 
 describe "Global variable $VERBOSE" do
+  before :each do
+    @verbose = $VERBOSE
+  end
+
+  after :each do
+    $VERBOSE = @verbose
+  end
+
+  it "is false by default" do
+    $VERBOSE.should == false
+  end
+
   it "converts truthy values to true" do
     [true, 1, 0, [], ""].each do |true_value|
       $VERBOSE = true_value
-      $VERBOSE.should be_true
+      $VERBOSE.should == true
     end
   end
 
   it "allows false" do
     $VERBOSE = false
-    $VERBOSE.should be_false
+    $VERBOSE.should == false
   end
 
   it "allows nil without coercing to false" do
     $VERBOSE = nil
-    $VERBOSE.should be_nil
+    $VERBOSE.should == nil
   end
 end
 
@@ -926,9 +1224,9 @@ describe :verbose_global_alias, shared: true do
 
   it "is an alias of $VERBOSE" do
     $VERBOSE = true
-    eval(@method).should be_true
+    eval(@method).should == true
     eval("#{@method} = false")
-    $VERBOSE.should be_false
+    $VERBOSE.should == false
   end
 end
 
@@ -951,7 +1249,7 @@ describe "Global variable $0" do
 
   it "is the path given as the main script and the same as __FILE__" do
     script = "fixtures/dollar_zero.rb"
-    Dir.chdir(File.dirname(__FILE__)) do
+    Dir.chdir(__dir__) do
       ruby_exe(script).should == "#{script}\n#{script}\nOK"
     end
   end
@@ -965,7 +1263,7 @@ describe "Global variable $0" do
     it "actually sets the program name" do
       title = "rubyspec-dollar0-test"
       $0 = title
-      `ps -ocommand= -p#{$$}`.should include(title)
+      `ps -ocommand= -p#{$$}`.should.include?(title)
     end
   end
 
@@ -974,26 +1272,24 @@ describe "Global variable $0" do
   end
 
   it "raises a TypeError when not given an object that can be coerced to a String" do
-    -> { $0 = nil }.should raise_error(TypeError)
+    -> { $0 = nil }.should.raise(TypeError)
   end
 end
 
-=begin
-Standard Objects
----------------------------------------------------------------------------------------------------
-
-ARGF             Object          A synonym for $<.
-ARGV             Array           A synonym for $*.
-ENV              Object          A hash-like object containing the program’s environment variables. An
-                                 instance of class Object, ENV implements the full set of Hash methods. Used
-                                 to query and set the value of an environment variable, as in ENV["PATH"]
-                                 and ENV["term"]="ansi".
-false            FalseClass      Singleton instance of class FalseClass. [r/o]
-nil              NilClass        The singleton instance of class NilClass. The value of uninitialized
-                                 instance and global variables. [r/o]
-self             Object          The receiver (object) of the current method. [r/o]
-true             TrueClass       Singleton instance of class TrueClass. [r/o]
-=end
+# Standard Objects
+# ---------------------------------------------------------------------------------------------------
+#
+# ARGF             Object          A synonym for $<.
+# ARGV             Array           A synonym for $*.
+# ENV              Object          A hash-like object containing the program’s environment variables. An
+#                                  instance of class Object, ENV implements the full set of Hash methods. Used
+#                                  to query and set the value of an environment variable, as in ENV["PATH"]
+#                                  and ENV["term"]="ansi".
+# false            FalseClass      Singleton instance of class FalseClass. [r/o]
+# nil              NilClass        The singleton instance of class NilClass. The value of uninitialized
+#                                  instance and global variables. [r/o]
+# self             Object          The receiver (object) of the current method. [r/o]
+# true             TrueClass       Singleton instance of class TrueClass. [r/o]
 
 describe "The predefined standard objects" do
   it "includes ARGF" do
@@ -1012,91 +1308,86 @@ end
 
 describe "The predefined standard object nil" do
   it "is an instance of NilClass" do
-    nil.should be_kind_of(NilClass)
+    nil.should.is_a?(NilClass)
   end
 
   it "raises a SyntaxError if assigned to" do
-    -> { eval("nil = true") }.should raise_error(SyntaxError)
+    -> { eval("nil = true") }.should.raise(SyntaxError, /Can't assign to nil/)
   end
 end
 
 describe "The predefined standard object true" do
   it "is an instance of TrueClass" do
-    true.should be_kind_of(TrueClass)
+    true.should.is_a?(TrueClass)
   end
 
   it "raises a SyntaxError if assigned to" do
-    -> { eval("true = false") }.should raise_error(SyntaxError)
+    -> { eval("true = false") }.should.raise(SyntaxError, /Can't assign to true/)
   end
 end
 
 describe "The predefined standard object false" do
   it "is an instance of FalseClass" do
-    false.should be_kind_of(FalseClass)
+    false.should.is_a?(FalseClass)
   end
 
   it "raises a SyntaxError if assigned to" do
-    -> { eval("false = nil") }.should raise_error(SyntaxError)
+    -> { eval("false = nil") }.should.raise(SyntaxError, /Can't assign to false/)
   end
 end
 
 describe "The self pseudo-variable" do
   it "raises a SyntaxError if assigned to" do
-    -> { eval("self = 1") }.should raise_error(SyntaxError)
+    -> { eval("self = 1") }.should.raise(SyntaxError, /Can't change the value of self/)
   end
 end
 
-=begin
-Global Constants
----------------------------------------------------------------------------------------------------
-
-The following constants are defined by the Ruby interpreter.
-
-DATA                 IO          If the main program file contains the directive __END__, then
-                                 the constant DATA will be initialized so that reading from it will
-                                 return lines following __END__ from the source file.
-FALSE                FalseClass  Synonym for false.
-NIL                  NilClass    Synonym for nil.
-RUBY_PLATFORM        String      The identifier of the platform running this program. This string
-                                 is in the same form as the platform identifier used by the GNU
-                                 configure utility (which is not a coincidence).
-RUBY_RELEASE_DATE    String      The date of this release.
-RUBY_VERSION         String      The version number of the interpreter.
-STDERR               IO          The actual standard error stream for the program. The initial
-                                 value of $stderr.
-STDIN                IO          The actual standard input stream for the program. The initial
-                                 value of $stdin.
-STDOUT               IO          The actual standard output stream for the program. The initial
-                                 value of $stdout.
-SCRIPT_LINES__       Hash        If a constant SCRIPT_LINES__ is defined and references a Hash,
-                                 Ruby will store an entry containing the contents of each file it
-                                 parses, with the file’s name as the key and an array of strings as
-                                 the value.
-TOPLEVEL_BINDING     Binding     A Binding object representing the binding at Ruby’s top level—
-                                 the level where programs are initially executed.
-TRUE                 TrueClass   Synonym for true.
-=end
+# Global Constants
+# ---------------------------------------------------------------------------------------------------
+#
+# The following constants are defined by the Ruby interpreter.
+#
+# DATA                 IO          If the main program file contains the directive __END__, then
+#                                  the constant DATA will be initialized so that reading from it will
+#                                  return lines following __END__ from the source file.
+# FALSE                FalseClass  Synonym for false (deprecated, removed in Ruby 3).
+# NIL                  NilClass    Synonym for nil (deprecated, removed in Ruby 3).
+# RUBY_PLATFORM        String      The identifier of the platform running this program. This string
+#                                  is in the same form as the platform identifier used by the GNU
+#                                  configure utility (which is not a coincidence).
+# RUBY_RELEASE_DATE    String      The date of this release.
+# RUBY_VERSION         String      The version number of the interpreter.
+# STDERR               IO          The actual standard error stream for the program. The initial
+#                                  value of $stderr.
+# STDIN                IO          The actual standard input stream for the program. The initial
+#                                  value of $stdin.
+# STDOUT               IO          The actual standard output stream for the program. The initial
+#                                  value of $stdout.
+# SCRIPT_LINES__       Hash        If a constant SCRIPT_LINES__ is defined and references a Hash,
+#                                  Ruby will store an entry containing the contents of each file it
+#                                  parses, with the file’s name as the key and an array of strings as
+#                                  the value.
+# TOPLEVEL_BINDING     Binding     A Binding object representing the binding at Ruby’s top level—
+#                                  the level where programs are initially executed.
+# TRUE                 TrueClass   Synonym for true (deprecated, removed in Ruby 3).
 
 describe "The predefined global constants" do
-  it "includes TRUE" do
-    Object.const_defined?(:TRUE).should == true
-    -> {
-      TRUE.should equal(true)
-    }.should complain(/constant ::TRUE is deprecated/)
+  describe "TRUE" do
+    it "is no longer defined" do
+      Object.const_defined?(:TRUE).should == false
+    end
   end
 
-  it "includes FALSE" do
-    Object.const_defined?(:FALSE).should == true
-    -> {
-      FALSE.should equal(false)
-    }.should complain(/constant ::FALSE is deprecated/)
+  describe "FALSE" do
+    it "is no longer defined" do
+      Object.const_defined?(:FALSE).should == false
+    end
   end
 
-  it "includes NIL" do
-    Object.const_defined?(:NIL).should == true
-    -> {
-      NIL.should equal(nil)
-    }.should complain(/constant ::NIL is deprecated/)
+  describe "NIL" do
+    it "is no longer defined" do
+      Object.const_defined?(:NIL).should == false
+    end
   end
 
   it "includes STDIN" do
@@ -1126,7 +1417,6 @@ describe "The predefined global constants" do
   it "includes TOPLEVEL_BINDING" do
     Object.const_defined?(:TOPLEVEL_BINDING).should == true
   end
-
 end
 
 describe "The predefined global constant" do
@@ -1141,13 +1431,24 @@ describe "The predefined global constant" do
   end
 
   describe "STDIN" do
-    it "has the same external encoding as Encoding.default_external" do
-      STDIN.external_encoding.should equal(Encoding.default_external)
-    end
+    platform_is_not :windows do
+      it "has the same external encoding as Encoding.default_external" do
+        STDIN.external_encoding.should.equal?(Encoding.default_external)
+      end
+
+      it "has the same external encoding as Encoding.default_external when that encoding is changed" do
+        Encoding.default_external = Encoding::ISO_8859_16
+        STDIN.external_encoding.should.equal?(Encoding::ISO_8859_16)
+      end
+
+      it "has nil for the internal encoding" do
+        STDIN.internal_encoding.should == nil
+      end
 
-    it "has the same external encoding as Encoding.default_external when that encoding is changed" do
-      Encoding.default_external = Encoding::ISO_8859_16
-      STDIN.external_encoding.should equal(Encoding::ISO_8859_16)
+      it "has nil for the internal encoding despite Encoding.default_internal being changed" do
+        Encoding.default_internal = Encoding::IBM437
+        STDIN.internal_encoding.should == nil
+      end
     end
 
     it "has the encodings set by #set_encoding" do
@@ -1162,25 +1463,16 @@ describe "The predefined global constant" do
              "p [STDIN.external_encoding.name, STDIN.internal_encoding.name]"
       ruby_exe(code).chomp.should == %{["IBM775", "IBM866"]}
     end
-
-    it "has nil for the internal encoding" do
-      STDIN.internal_encoding.should be_nil
-    end
-
-    it "has nil for the internal encoding despite Encoding.default_internal being changed" do
-      Encoding.default_internal = Encoding::IBM437
-      STDIN.internal_encoding.should be_nil
-    end
   end
 
   describe "STDOUT" do
     it "has nil for the external encoding" do
-      STDOUT.external_encoding.should be_nil
+      STDOUT.external_encoding.should == nil
     end
 
     it "has nil for the external encoding despite Encoding.default_external being changed" do
       Encoding.default_external = Encoding::ISO_8859_1
-      STDOUT.external_encoding.should be_nil
+      STDOUT.external_encoding.should == nil
     end
 
     it "has the encodings set by #set_encoding" do
@@ -1190,23 +1482,23 @@ describe "The predefined global constant" do
     end
 
     it "has nil for the internal encoding" do
-      STDOUT.internal_encoding.should be_nil
+      STDOUT.internal_encoding.should == nil
     end
 
     it "has nil for the internal encoding despite Encoding.default_internal being changed" do
       Encoding.default_internal = Encoding::IBM437
-      STDOUT.internal_encoding.should be_nil
+      STDOUT.internal_encoding.should == nil
     end
   end
 
   describe "STDERR" do
     it "has nil for the external encoding" do
-      STDERR.external_encoding.should be_nil
+      STDERR.external_encoding.should == nil
     end
 
     it "has nil for the external encoding despite Encoding.default_external being changed" do
       Encoding.default_external = Encoding::ISO_8859_1
-      STDERR.external_encoding.should be_nil
+      STDERR.external_encoding.should == nil
     end
 
     it "has the encodings set by #set_encoding" do
@@ -1216,12 +1508,12 @@ describe "The predefined global constant" do
     end
 
     it "has nil for the internal encoding" do
-      STDERR.internal_encoding.should be_nil
+      STDERR.internal_encoding.should == nil
     end
 
     it "has nil for the internal encoding despite Encoding.default_internal being changed" do
       Encoding.default_internal = Encoding::IBM437
-      STDERR.internal_encoding.should be_nil
+      STDERR.internal_encoding.should == nil
     end
   end
 
@@ -1234,3 +1526,50 @@ describe "The predefined global constant" do
     end
   end
 end
+
+describe "$LOAD_PATH.resolve_feature_path" do
+  it "returns what will be loaded without actual loading, .rb file" do
+    extension, path = $LOAD_PATH.resolve_feature_path('pp')
+    extension.should == :rb
+    path.should.end_with?('/pp.rb')
+  end
+
+  it "returns what will be loaded without actual loading, .so file" do
+    require 'rbconfig'
+    skip "no dynamically loadable standard extension" if RbConfig::CONFIG["EXTSTATIC"] == "static"
+
+    extension, path = $LOAD_PATH.resolve_feature_path('etc')
+    extension.should == :so
+    path.should.end_with?("/etc.#{RbConfig::CONFIG['DLEXT']}")
+  end
+
+  it "return nil if feature cannot be found" do
+    $LOAD_PATH.resolve_feature_path('noop').should == nil
+  end
+end
+
+# Some other pre-defined global variables
+
+describe "Predefined global $=" do
+  before :each do
+    @verbose, $VERBOSE = $VERBOSE, nil
+    @dollar_assign = $=
+  end
+
+  after :each do
+    $= = @dollar_assign
+    $VERBOSE = @verbose
+  end
+
+  it "warns when accessed" do
+    -> { a = $= }.should complain(/is no longer effective/)
+  end
+
+  it "warns when assigned" do
+    -> { $= = "_" }.should complain(/is no longer effective/)
+  end
+
+  it "returns the value assigned" do
+    ($= = "xyz").should == "xyz"
+  end
+end
diff --git a/spec/ruby/language/private_spec.rb b/spec/ruby/language/private_spec.rb
index ddf185e6d2..94b56fee5b 100644
--- a/spec/ruby/language/private_spec.rb
+++ b/spec/ruby/language/private_spec.rb
@@ -4,12 +4,12 @@ require_relative 'fixtures/private'
 describe "The private keyword" do
   it "marks following methods as being private" do
     a = Private::A.new
-    a.methods.should_not include(:bar)
-    -> { a.bar }.should raise_error(NoMethodError)
+    a.methods.should_not.include?(:bar)
+    -> { a.bar }.should.raise(NoMethodError)
 
     b = Private::B.new
-    b.methods.should_not include(:bar)
-    -> { b.bar }.should raise_error(NoMethodError)
+    b.methods.should_not.include?(:bar)
+    -> { b.bar }.should.raise(NoMethodError)
   end
 
   # def expr.meth() methods are always public
@@ -19,22 +19,22 @@ describe "The private keyword" do
 
   it "is overridden when a new class is opened" do
     c = Private::B::C.new
-    c.methods.should include(:baz)
+    c.methods.should.include?(:baz)
     c.baz
     Private::B.public_class_method1.should == 1
-    -> { Private::B.private_class_method1 }.should raise_error(NoMethodError)
+    -> { Private::B.private_class_method1 }.should.raise(NoMethodError)
   end
 
   it "is no longer in effect when the class is closed" do
     b = Private::B.new
-    b.methods.should include(:foo)
+    b.methods.should.include?(:foo)
     b.foo
   end
 
   it "changes visibility of previously called method" do
     klass = Class.new do
       def foo
-       "foo"
+        "foo"
       end
     end
     f = klass.new
@@ -42,7 +42,7 @@ describe "The private keyword" do
     klass.class_eval do
       private :foo
     end
-    -> { f.foo }.should raise_error(NoMethodError)
+    -> { f.foo }.should.raise(NoMethodError)
   end
 
   it "changes visibility of previously called methods with same send/call site" do
@@ -56,12 +56,12 @@ describe "The private keyword" do
           end
         end
       end
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   it "changes the visibility of the existing method in the subclass" do
     ::Private::A.new.foo.should == 'foo'
-    -> { ::Private::H.new.foo }.should raise_error(NoMethodError)
+    -> { ::Private::H.new.foo }.should.raise(NoMethodError)
     ::Private::H.new.send(:foo).should == 'foo'
   end
 end
diff --git a/spec/ruby/language/proc_spec.rb b/spec/ruby/language/proc_spec.rb
index c44e711d2b..53a21d6b85 100644
--- a/spec/ruby/language/proc_spec.rb
+++ b/spec/ruby/language/proc_spec.rb
@@ -22,7 +22,7 @@ describe "A Proc" do
     end
 
     it "raises an ArgumentError if a value is passed" do
-      lambda { @l.call(0) }.should raise_error(ArgumentError)
+      lambda { @l.call(0) }.should.raise(ArgumentError)
     end
   end
 
@@ -36,7 +36,7 @@ describe "A Proc" do
     end
 
     it "raises an ArgumentError if a value is passed" do
-      lambda { @l.call(0) }.should raise_error(ArgumentError)
+      lambda { @l.call(0) }.should.raise(ArgumentError)
     end
   end
 
@@ -57,11 +57,11 @@ describe "A Proc" do
       obj = mock("block yield to_ary")
       obj.should_not_receive(:to_ary)
 
-      @l.call(obj).should equal(obj)
+      @l.call(obj).should.equal?(obj)
     end
 
     it "raises an ArgumentError if no value is passed" do
-      lambda { @l.call }.should raise_error(ArgumentError)
+      lambda { @l.call }.should.raise(ArgumentError)
     end
   end
 
@@ -71,11 +71,11 @@ describe "A Proc" do
     end
 
     it "raises an ArgumentError if passed no values" do
-      lambda { @l.call }.should raise_error(ArgumentError)
+      lambda { @l.call }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError if passed one value" do
-      lambda { @l.call(0) }.should raise_error(ArgumentError)
+      lambda { @l.call(0) }.should.raise(ArgumentError)
     end
 
     it "assigns the values passed to the arguments" do
@@ -86,7 +86,7 @@ describe "A Proc" do
       obj = mock("proc call to_ary")
       obj.should_not_receive(:to_ary)
 
-      lambda { @l.call(obj) }.should raise_error(ArgumentError)
+      lambda { @l.call(obj) }.should.raise(ArgumentError)
     end
   end
 
@@ -96,7 +96,7 @@ describe "A Proc" do
     end
 
     it "raises an ArgumentError if passed no values" do
-      lambda { @l.call }.should raise_error(ArgumentError)
+      lambda { @l.call }.should.raise(ArgumentError)
     end
 
     it "does not destructure a single Array value yielded" do
@@ -104,7 +104,7 @@ describe "A Proc" do
     end
 
     it "assigns all passed values after the first to the rest argument" do
-        @l.call(1, 2, 3).should == [1, [2, 3]]
+      @l.call(1, 2, 3).should == [1, [2, 3]]
     end
 
     it "does not call #to_ary to convert a single passed object to an Array" do
@@ -161,17 +161,29 @@ describe "A Proc" do
     end
   end
 
+  describe "taking |*a, b| arguments" do
+    it "assigns [] to the argument when passed no values" do
+      proc { |*a, b| [a, b] }.call.should == [[], nil]
+    end
+  end
+
+  describe "taking |a, *b, c| arguments" do
+    it "assigns [] to the argument when passed no values" do
+      proc { |a, *b, c| [a, b, c] }.call.should == [nil, [], nil]
+    end
+  end
+
   describe "taking |a, | arguments" do
     before :each do
       @l = lambda { |a, | a }
     end
 
     it "raises an ArgumentError when passed no values" do
-      lambda { @l.call }.should raise_error(ArgumentError)
+      lambda { @l.call }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError when passed more than one value" do
-      lambda { @l.call(1, 2) }.should raise_error(ArgumentError)
+      lambda { @l.call(1, 2) }.should.raise(ArgumentError)
     end
 
     it "assigns the argument the value passed" do
@@ -196,7 +208,7 @@ describe "A Proc" do
     end
 
     it "raises an ArgumentError when passed no values" do
-      lambda { @l.call }.should raise_error(ArgumentError)
+      lambda { @l.call }.should.raise(ArgumentError)
     end
 
     it "destructures a single Array value yielded" do
@@ -214,7 +226,42 @@ describe "A Proc" do
       obj = mock("block yield to_ary invalid")
       obj.should_receive(:to_ary).and_return(1)
 
-      lambda { @l.call(obj) }.should raise_error(TypeError)
+      lambda { @l.call(obj) }.should.raise(TypeError)
+    end
+  end
+
+  describe "taking |*a, **kw| arguments" do
+    before :each do
+      @p = proc { |*a, **kw| [a, kw] }
     end
+
+    it 'does not autosplat keyword arguments' do
+      @p.call([1, {a: 1}]).should == [[[1, {a: 1}]], {}]
+    end
+  end
+
+  describe "taking |required keyword arguments, **kw| arguments" do
+    it "raises ArgumentError for missing required argument" do
+      p = proc { |a:, **kw| [a, kw] }
+      -> { p.call() }.should.raise(ArgumentError)
+    end
+  end
+
+  evaluate <<-ruby do
+    @p = proc { |**nil| :ok }
+    ruby
+
+    @p.call().should == :ok
+    -> { @p.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
+    -> { @p.call(**{a: 1}) }.should.raise(ArgumentError, 'no keywords accepted')
+    -> { @p.call("a" => 1) }.should.raise(ArgumentError, 'no keywords accepted')
+  end
+
+  evaluate <<-ruby do
+    @p = proc { |a, **nil| a }
+    ruby
+
+    @p.call({a: 1}).should == {a: 1}
+    -> { @p.call(a: 1) }.should.raise(ArgumentError, 'no keywords accepted')
   end
 end
diff --git a/spec/ruby/language/range_spec.rb b/spec/ruby/language/range_spec.rb
index c720c5b98e..ccc9f55537 100644
--- a/spec/ruby/language/range_spec.rb
+++ b/spec/ruby/language/range_spec.rb
@@ -10,10 +10,21 @@ describe "Literal Ranges" do
     (1...10).should == Range.new(1, 10, true)
   end
 
-  ruby_version_is "2.6" do
-    it "creates endless ranges" do
-      eval("(1..)").should == Range.new(1, nil)
-      eval("(1...)").should == Range.new(1, nil, true)
+  it "creates a simple range as an object literal" do
+    ary = []
+    2.times do
+      ary.push(1..3)
     end
+    ary[0].should.equal?(ary[1])
+  end
+
+  it "creates endless ranges" do
+    (1..).should == Range.new(1, nil)
+    (1...).should == Range.new(1, nil, true)
+  end
+
+  it "creates beginless ranges" do
+    (..1).should == Range.new(nil, 1)
+    (...1).should == Range.new(nil, 1, true)
   end
 end
diff --git a/spec/ruby/language/redo_spec.rb b/spec/ruby/language/redo_spec.rb
index 57532553b3..9b14c5add1 100644
--- a/spec/ruby/language/redo_spec.rb
+++ b/spec/ruby/language/redo_spec.rb
@@ -60,7 +60,7 @@ describe "The redo statement" do
     it "is invalid and raises a SyntaxError" do
       -> {
         eval("def m; redo; end")
-      }.should raise_error(SyntaxError)
+      }.should.raise(SyntaxError)
     end
   end
 end
diff --git a/spec/ruby/language/regexp/anchors_spec.rb b/spec/ruby/language/regexp/anchors_spec.rb
index 0129e255da..8e597b65e8 100644
--- a/spec/ruby/language/regexp/anchors_spec.rb
+++ b/spec/ruby/language/regexp/anchors_spec.rb
@@ -7,8 +7,8 @@ describe "Regexps with anchors" do
     /^foo/.match("foo").to_a.should == ["foo"]
     /^bar/.match("foo\nbar").to_a.should == ["bar"]
     # Basic non-matching
-    /^foo/.match(" foo").should be_nil
-    /foo^/.match("foo\n\n\n").should be_nil
+    /^foo/.match(" foo").should == nil
+    /foo^/.match("foo\n\n\n").should == nil
 
     # A bit advanced
     /^^^foo/.match("foo").to_a.should == ["foo"]
@@ -16,8 +16,8 @@ describe "Regexps with anchors" do
     (/($^)($^)/ =~ "foo\n\n").should == "foo\n".size and $~.to_a.should == ["", "", ""]
 
     # Different start of line chars
-    /^bar/.match("foo\rbar").should be_nil
-    /^bar/.match("foo\0bar").should be_nil
+    /^bar/.match("foo\rbar").should == nil
+    /^bar/.match("foo\0bar").should == nil
 
     # Trivial
     /^/.match("foo").to_a.should == [""]
@@ -29,7 +29,7 @@ describe "Regexps with anchors" do
   end
 
   it "does not match ^ after trailing \\n" do
-    /^(?!\A)/.match("foo\n").should be_nil # There is no (empty) line after a trailing \n
+    /^(?!\A)/.match("foo\n").should == nil # There is no (empty) line after a trailing \n
   end
 
   it "supports $ (line end anchor)" do
@@ -37,16 +37,16 @@ describe "Regexps with anchors" do
     /foo$/.match("foo").to_a.should == ["foo"]
     /foo$/.match("foo\nbar").to_a.should == ["foo"]
     # Basic non-matching
-    /foo$/.match("foo ").should be_nil
-    /$foo/.match("\n\n\nfoo").should be_nil
+    /foo$/.match("foo ").should == nil
+    /$foo/.match("\n\n\nfoo").should == nil
 
     # A bit advanced
     /foo$$$/.match("foo").to_a.should == ["foo"]
     (/[^o]$/ =~ "foo\n\n").should == ("foo\n".size - 1) and $~.to_a.should == ["\n"]
 
     # Different end of line chars
-    /foo$/.match("foo\r\nbar").should be_nil
-    /foo$/.match("foo\0bar").should be_nil
+    /foo$/.match("foo\r\nbar").should == nil
+    /foo$/.match("foo\0bar").should == nil
 
     # Trivial
     (/$/ =~ "foo").should == "foo".size and $~.to_a.should == [""]
@@ -61,15 +61,15 @@ describe "Regexps with anchors" do
     # Basic matching
     /\Afoo/.match("foo").to_a.should == ["foo"]
     # Basic non-matching
-    /\Abar/.match("foo\nbar").should be_nil
-    /\Afoo/.match(" foo").should be_nil
+    /\Abar/.match("foo\nbar").should == nil
+    /\Afoo/.match(" foo").should == nil
 
     # A bit advanced
     /\A\A\Afoo/.match("foo").to_a.should == ["foo"]
     /(\A\Z)(\A\Z)/.match("").to_a.should == ["", "", ""]
 
     # Different start of line chars
-    /\Abar/.match("foo\0bar").should be_nil
+    /\Abar/.match("foo\0bar").should == nil
 
     # Grouping
     /(\Afoo)/.match("foo").to_a.should == ["foo", "foo"]
@@ -81,8 +81,8 @@ describe "Regexps with anchors" do
     /foo\Z/.match("foo").to_a.should == ["foo"]
     /foo\Z/.match("foo\n").to_a.should == ["foo"]
     # Basic non-matching
-    /foo\Z/.match("foo\nbar").should be_nil
-    /foo\Z/.match("foo ").should be_nil
+    /foo\Z/.match("foo\nbar").should == nil
+    /foo\Z/.match("foo ").should == nil
 
     # A bit advanced
     /foo\Z\Z\Z/.match("foo\n").to_a.should == ["foo"]
@@ -90,8 +90,8 @@ describe "Regexps with anchors" do
     (/(\z\Z)(\z\Z)/ =~ "foo\n").should == "foo\n".size and $~.to_a.should == ["", "", ""]
 
     # Different end of line chars
-    /foo\Z/.match("foo\0bar").should be_nil
-    /foo\Z/.match("foo\r\n").should be_nil
+    /foo\Z/.match("foo\0bar").should == nil
+    /foo\Z/.match("foo\r\n").should == nil
 
     # Grouping
     /(foo\Z)/.match("foo").to_a.should == ["foo", "foo"]
@@ -102,17 +102,17 @@ describe "Regexps with anchors" do
     # Basic matching
     /foo\z/.match("foo").to_a.should == ["foo"]
     # Basic non-matching
-    /foo\z/.match("foo\nbar").should be_nil
-    /foo\z/.match("foo\n").should be_nil
-    /foo\z/.match("foo ").should be_nil
+    /foo\z/.match("foo\nbar").should == nil
+    /foo\z/.match("foo\n").should == nil
+    /foo\z/.match("foo ").should == nil
 
     # A bit advanced
     /foo\z\z\z/.match("foo").to_a.should == ["foo"]
     (/($\z)($\z)/ =~ "foo").should == "foo".size and $~.to_a.should == ["", "", ""]
 
     # Different end of line chars
-    /foo\z/.match("foo\0bar").should be_nil
-    /foo\z/.match("foo\r\nbar").should be_nil
+    /foo\z/.match("foo\0bar").should == nil
+    /foo\z/.match("foo\r\nbar").should == nil
 
     # Grouping
     /(foo\z)/.match("foo").to_a.should == ["foo", "foo"]
@@ -124,16 +124,16 @@ describe "Regexps with anchors" do
     /foo\b/.match("foo").to_a.should == ["foo"]
     /foo\b/.match("foo\n").to_a.should == ["foo"]
     LanguageSpecs.white_spaces.scan(/./).each do |c|
-    /foo\b/.match("foo" + c).to_a.should == ["foo"]
+      /foo\b/.match("foo" + c).to_a.should == ["foo"]
     end
     LanguageSpecs.non_alphanum_non_space.scan(/./).each do |c|
-    /foo\b/.match("foo" + c).to_a.should == ["foo"]
+      /foo\b/.match("foo" + c).to_a.should == ["foo"]
     end
     /foo\b/.match("foo\0").to_a.should == ["foo"]
     # Basic non-matching
-    /foo\b/.match("foobar").should be_nil
-    /foo\b/.match("foo123").should be_nil
-    /foo\b/.match("foo_").should be_nil
+    /foo\b/.match("foobar").should == nil
+    /foo\b/.match("foo123").should == nil
+    /foo\b/.match("foo_").should == nil
   end
 
   it "supports \\B (non-word-boundary)" do
@@ -142,15 +142,15 @@ describe "Regexps with anchors" do
     /foo\B/.match("foo123").to_a.should == ["foo"]
     /foo\B/.match("foo_").to_a.should == ["foo"]
     # Basic non-matching
-    /foo\B/.match("foo").should be_nil
-    /foo\B/.match("foo\n").should be_nil
+    /foo\B/.match("foo").should == nil
+    /foo\B/.match("foo\n").should == nil
     LanguageSpecs.white_spaces.scan(/./).each do |c|
-    /foo\B/.match("foo" + c).should be_nil
+      /foo\B/.match("foo" + c).should == nil
     end
     LanguageSpecs.non_alphanum_non_space.scan(/./).each do |c|
-    /foo\B/.match("foo" + c).should be_nil
+      /foo\B/.match("foo" + c).should == nil
     end
-    /foo\B/.match("foo\0").should be_nil
+    /foo\B/.match("foo\0").should == nil
   end
 
   it "supports (?= ) (positive lookahead)" do
diff --git a/spec/ruby/language/regexp/back-references_spec.rb b/spec/ruby/language/regexp/back-references_spec.rb
index 81015ac21e..3b4c5656a2 100644
--- a/spec/ruby/language/regexp/back-references_spec.rb
+++ b/spec/ruby/language/regexp/back-references_spec.rb
@@ -22,6 +22,15 @@ describe "Regexps with back-references" do
     $10.should == "0"
   end
 
+  it "returns nil for numbered variable with too large index" do
+    -> {
+      eval(<<~CODE).should == nil
+        "a" =~ /(.)/
+        eval('$4294967296')
+      CODE
+    }.should complain(/warning: ('|`)\$4294967296' is too big for a number variable, always nil/)
+  end
+
   it "will not clobber capture variables across threads" do
     cap1, cap2, cap3 = nil
     "foo" =~ /(o+)/
@@ -40,14 +49,101 @@ describe "Regexps with back-references" do
 
   it "supports \<n> (backreference to previous group match)" do
     /(foo.)\1/.match("foo1foo1").to_a.should == ["foo1foo1", "foo1"]
-    /(foo.)\1/.match("foo1foo2").should be_nil
+    /(foo.)\1/.match("foo1foo2").should == nil
   end
 
   it "resets nested \<n> backreference before match of outer subexpression" do
     /(a\1?){2}/.match("aaaa").to_a.should == ["aa", "a"]
   end
 
+  it "does not reset enclosed capture groups" do
+    /((a)|(b))+/.match("ab").captures.should == [ "b", "a", "b" ]
+  end
+
   it "can match an optional quote, followed by content, followed by a matching quote, as the whole string" do
     /^("|)(.*)\1$/.match('x').to_a.should == ["x", "", "x"]
   end
+
+  it "allows forward references" do
+    /(?:(\2)|(.))+/.match("aa").to_a.should == [ "aa", "a", "a" ]
+  end
+
+  it "disallows forward references >= 10" do
+    (/\10()()()()()()()()()()/ =~ "\x08").should == 0
+  end
+
+  it "fails when trying to match a backreference to an unmatched capture group" do
+    /\1()/.match("").should == nil
+    /(?:(a)|b)\1/.match("b").should == nil
+  end
+
+  it "ignores backreferences > 1000" do
+    /\99999/.match("99999")[0].should == "99999"
+  end
+
+  it "0 is not a valid backreference" do
+    -> { Regexp.new("\\k<0>") }.should.raise(RegexpError)
+  end
+
+  it "allows numeric conditional backreferences" do
+    /(a)(?(1)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?(<1>)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?('1')a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+
+  it "allows either <> or '' in named conditional backreferences" do
+    -> { Regexp.new("(?<a>a)(?(a)a|b)") }.should.raise(RegexpError)
+    /(?<a>a)(?(<a>)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a>a)(?('a')a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+
+  it "allows negative numeric backreferences" do
+    /(a)\k<-1>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)\g<-1>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?(<-1>)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?('-1')a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+
+  it "delimited numeric backreferences can start with 0" do
+    /(a)\k<01>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)\g<01>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?(01)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?(<01>)a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+    /(a)(?('01')a|b)/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+
+  it "regular numeric backreferences cannot start with 0" do
+    /(a)\01/.match("aa").should == nil
+    /(a)\01/.match("a\x01").to_a.should == [ "a\x01", "a" ]
+  end
+
+  it "named capture groups invalidate numeric backreferences" do
+    -> { Regexp.new("(?<a>a)\\1") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a>a)\\k<1>") }.should.raise(RegexpError)
+    -> { Regexp.new("(a)(?<a>a)\\1") }.should.raise(RegexpError)
+    -> { Regexp.new("(a)(?<a>a)\\k<1>") }.should.raise(RegexpError)
+  end
+
+  it "treats + or - as the beginning of a level specifier in \\k<> backreferences and (?(...)...|...) conditional backreferences" do
+    -> { Regexp.new("(?<a+>a)\\k<a+>") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+b>a)\\k<a+b>") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+1>a)\\k<a+1>") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a->a)\\k<a->") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-b>a)\\k<a-b>") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-1>a)\\k<a-1>") }.should.raise(RegexpError)
+
+    -> { Regexp.new("(?<a+>a)(?(<a+>)a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+b>a)(?(<a+b>)a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+1>a)(?(<a+1>)a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a->a)(?(<a->)a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-b>a)(?(<a-b>)a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-1>a)(?(<a-1>)a|b)") }.should.raise(RegexpError)
+
+    -> { Regexp.new("(?<a+>a)(?('a+')a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+b>a)(?('a+b')a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a+1>a)(?('a+1')a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a->a)(?('a-')a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-b>a)(?('a-b')a|b)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<a-1>a)(?('a-1')a|b)") }.should.raise(RegexpError)
+  end
 end
diff --git a/spec/ruby/language/regexp/character_classes_spec.rb b/spec/ruby/language/regexp/character_classes_spec.rb
index 5f4221e213..c6ed92b78e 100644
--- a/spec/ruby/language/regexp/character_classes_spec.rb
+++ b/spec/ruby/language/regexp/character_classes_spec.rb
@@ -9,9 +9,9 @@ describe "Regexp with character classes" do
     /\w/.match("_").to_a.should == ["_"]
 
     # Non-matches
-    /\w/.match(LanguageSpecs.white_spaces).should be_nil
-    /\w/.match(LanguageSpecs.non_alphanum_non_space).should be_nil
-    /\w/.match("\0").should be_nil
+    /\w/.match(LanguageSpecs.white_spaces).should == nil
+    /\w/.match(LanguageSpecs.non_alphanum_non_space).should == nil
+    /\w/.match("\0").should == nil
   end
 
   it "supports \\W (non-word character)" do
@@ -20,19 +20,19 @@ describe "Regexp with character classes" do
     /\W/.match("\0").to_a.should == ["\0"]
 
     # Non-matches
-    /\W/.match("a").should be_nil
-    /\W/.match("1").should be_nil
-    /\W/.match("_").should be_nil
+    /\W/.match("a").should == nil
+    /\W/.match("1").should == nil
+    /\W/.match("_").should == nil
   end
 
   it "supports \\s (space character)" do
     /\s+/.match(LanguageSpecs.white_spaces).to_a.should == [LanguageSpecs.white_spaces]
 
     # Non-matches
-    /\s/.match("a").should be_nil
-    /\s/.match("1").should be_nil
-    /\s/.match(LanguageSpecs.non_alphanum_non_space).should be_nil
-    /\s/.match("\0").should be_nil
+    /\s/.match("a").should == nil
+    /\s/.match("1").should == nil
+    /\s/.match(LanguageSpecs.non_alphanum_non_space).should == nil
+    /\s/.match("\0").should == nil
   end
 
   it "supports \\S (non-space character)" do
@@ -42,17 +42,17 @@ describe "Regexp with character classes" do
     /\S/.match("\0").to_a.should == ["\0"]
 
     # Non-matches
-    /\S/.match(LanguageSpecs.white_spaces).should be_nil
+    /\S/.match(LanguageSpecs.white_spaces).should == nil
   end
 
   it "supports \\d (numeric digit)" do
     /\d/.match("1").to_a.should == ["1"]
 
     # Non-matches
-    /\d/.match("a").should be_nil
-    /\d/.match(LanguageSpecs.white_spaces).should be_nil
-    /\d/.match(LanguageSpecs.non_alphanum_non_space).should be_nil
-    /\d/.match("\0").should be_nil
+    /\d/.match("a").should == nil
+    /\d/.match(LanguageSpecs.white_spaces).should == nil
+    /\d/.match(LanguageSpecs.non_alphanum_non_space).should == nil
+    /\d/.match("\0").should == nil
   end
 
   it "supports \\D (non-digit)" do
@@ -62,7 +62,7 @@ describe "Regexp with character classes" do
     /\D/.match("\0").to_a.should == ["\0"]
 
     # Non-matches
-    /\D/.match("1").should be_nil
+    /\D/.match("1").should == nil
   end
 
   it "supports [] (character class)" do
@@ -89,7 +89,7 @@ describe "Regexp with character classes" do
     /[^[:lower:]A-C]+/.match("abcABCDEF123def").to_a.should == ["DEF123"] # negated character class
     /[:alnum:]+/.match("a:l:n:u:m").to_a.should == ["a:l:n:u:m"] # should behave like regular character class composed of the individual letters
     /[\[:alnum:]+/.match("[:a:l:n:u:m").to_a.should == ["[:a:l:n:u:m"] # should behave like regular character class composed of the individual letters
-    -> { eval('/[[:alpha:]-[:digit:]]/') }.should raise_error(SyntaxError) # can't use character class as a start value of range
+    -> { eval('/[[:alpha:]-[:digit:]]/') }.should.raise(SyntaxError) # can't use character class as a start value of range
   end
 
   it "matches ASCII characters with [[:ascii:]]" do
@@ -99,8 +99,8 @@ describe "Regexp with character classes" do
 
   not_supported_on :opal do
     it "doesn't match non-ASCII characters with [[:ascii:]]" do
-      /[[:ascii:]]/.match("\u{80}").should be_nil
-      /[[:ascii:]]/.match("\u{9898}").should be_nil
+      /[[:ascii:]]/.match("\u{80}").should == nil
+      /[[:ascii:]]/.match("\u{9898}").should == nil
     end
   end
 
@@ -113,7 +113,7 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't matches Unicode marks with [[:alnum:]]" do
-    "\u{36F}".match(/[[:alnum:]]/).should be_nil
+    "\u{3099}".match(/[[:alnum:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:alnum:]]" do
@@ -133,7 +133,7 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't matches Unicode marks with [[:alpha:]]" do
-    "\u{36F}".match(/[[:alpha:]]/).should be_nil
+    "\u{3099}".match(/[[:alpha:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:alpha:]]" do
@@ -149,39 +149,39 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode control characters with [[:blank:]]" do
-    "\u{16}".match(/[[:blank:]]/).should be_nil
+    "\u{16}".match(/[[:blank:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:blank:]]" do
-    "\u{3F}".match(/[[:blank:]]/).should be_nil
+    "\u{3F}".match(/[[:blank:]]/).should == nil
   end
 
   it "doesn't match Unicode letter characters with [[:blank:]]" do
-    "à".match(/[[:blank:]]/).should be_nil
+    "à".match(/[[:blank:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:blank:]]" do
-    "\u{0660}".match(/[[:blank:]]/).should be_nil
+    "\u{0660}".match(/[[:blank:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:blank:]]" do
-    "\u{36F}".match(/[[:blank:]]/).should be_nil
+    "\u{36F}".match(/[[:blank:]]/).should == nil
   end
 
   it "doesn't Unicode letter characters with [[:cntrl:]]" do
-    "à".match(/[[:cntrl:]]/).should be_nil
+    "à".match(/[[:cntrl:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:cntrl:]]" do
-    "\u{0660}".match(/[[:cntrl:]]/).should be_nil
+    "\u{0660}".match(/[[:cntrl:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:cntrl:]]" do
-    "\u{36F}".match(/[[:cntrl:]]/).should be_nil
+    "\u{36F}".match(/[[:cntrl:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:cntrl:]]" do
-    "\u{3F}".match(/[[:cntrl:]]/).should be_nil
+    "\u{3F}".match(/[[:cntrl:]]/).should == nil
   end
 
   it "matches Unicode control characters with [[:cntrl:]]" do
@@ -189,15 +189,15 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode format characters with [[:cntrl:]]" do
-    "\u{2060}".match(/[[:cntrl:]]/).should be_nil
+    "\u{2060}".match(/[[:cntrl:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:cntrl:]]" do
-    "\u{E001}".match(/[[:cntrl:]]/).should be_nil
+    "\u{E001}".match(/[[:cntrl:]]/).should == nil
   end
 
   it "doesn't match Unicode letter characters with [[:digit:]]" do
-    "à".match(/[[:digit:]]/).should be_nil
+    "à".match(/[[:digit:]]/).should == nil
   end
 
   it "matches Unicode digits with [[:digit:]]" do
@@ -206,27 +206,27 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode marks with [[:digit:]]" do
-    "\u{36F}".match(/[[:digit:]]/).should be_nil
+    "\u{36F}".match(/[[:digit:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:digit:]]" do
-    "\u{3F}".match(/[[:digit:]]/).should be_nil
+    "\u{3F}".match(/[[:digit:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:digit:]]" do
-    "\u{16}".match(/[[:digit:]]/).should be_nil
+    "\u{16}".match(/[[:digit:]]/).should == nil
   end
 
   it "doesn't match Unicode format characters with [[:digit:]]" do
-    "\u{2060}".match(/[[:digit:]]/).should be_nil
+    "\u{2060}".match(/[[:digit:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:digit:]]" do
-    "\u{E001}".match(/[[:digit:]]/).should be_nil
+    "\u{E001}".match(/[[:digit:]]/).should == nil
   end
 
   it "matches Unicode letter characters with [[:graph:]]" do
-      "à".match(/[[:graph:]]/).to_a.should == ["à"]
+    "à".match(/[[:graph:]]/).to_a.should == ["à"]
   end
 
   it "matches Unicode digits with [[:graph:]]" do
@@ -243,7 +243,7 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode control characters with [[:graph:]]" do
-    "\u{16}".match(/[[:graph:]]/).should be_nil
+    "\u{16}".match(/[[:graph:]]/).should == nil
   end
 
   it "match Unicode format characters with [[:graph:]]" do
@@ -261,40 +261,40 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode uppercase letter characters with [[:lower:]]" do
-    "\u{100}".match(/[[:lower:]]/).should be_nil
-    "\u{130}".match(/[[:lower:]]/).should be_nil
-    "\u{405}".match(/[[:lower:]]/).should be_nil
+    "\u{100}".match(/[[:lower:]]/).should == nil
+    "\u{130}".match(/[[:lower:]]/).should == nil
+    "\u{405}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode title-case characters with [[:lower:]]" do
-    "\u{1F88}".match(/[[:lower:]]/).should be_nil
-    "\u{1FAD}".match(/[[:lower:]]/).should be_nil
-    "\u{01C5}".match(/[[:lower:]]/).should be_nil
+    "\u{1F88}".match(/[[:lower:]]/).should == nil
+    "\u{1FAD}".match(/[[:lower:]]/).should == nil
+    "\u{01C5}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:lower:]]" do
-    "\u{0660}".match(/[[:lower:]]/).should be_nil
-    "\u{FF12}".match(/[[:lower:]]/).should be_nil
+    "\u{0660}".match(/[[:lower:]]/).should == nil
+    "\u{FF12}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:lower:]]" do
-    "\u{36F}".match(/[[:lower:]]/).should be_nil
+    "\u{36F}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:lower:]]" do
-    "\u{3F}".match(/[[:lower:]]/).should be_nil
+    "\u{3F}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:lower:]]" do
-    "\u{16}".match(/[[:lower:]]/).should be_nil
+    "\u{16}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode format characters with [[:lower:]]" do
-    "\u{2060}".match(/[[:lower:]]/).should be_nil
+    "\u{2060}".match(/[[:lower:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:lower:]]" do
-    "\u{E001}".match(/[[:lower:]]/).should be_nil
+    "\u{E001}".match(/[[:lower:]]/).should == nil
   end
 
   it "matches Unicode lowercase letter characters with [[:print:]]" do
@@ -329,7 +329,7 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode control characters with [[:print:]]" do
-    "\u{16}".match(/[[:print:]]/).should be_nil
+    "\u{16}".match(/[[:print:]]/).should == nil
   end
 
   it "match Unicode format characters with [[:print:]]" do
@@ -342,30 +342,30 @@ describe "Regexp with character classes" do
 
 
   it "doesn't match Unicode lowercase letter characters with [[:punct:]]" do
-    "\u{FF41}".match(/[[:punct:]]/).should be_nil
-    "\u{1D484}".match(/[[:punct:]]/).should be_nil
-    "\u{E8}".match(/[[:punct:]]/).should be_nil
+    "\u{FF41}".match(/[[:punct:]]/).should == nil
+    "\u{1D484}".match(/[[:punct:]]/).should == nil
+    "\u{E8}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode uppercase letter characters with [[:punct:]]" do
-    "\u{100}".match(/[[:punct:]]/).should be_nil
-    "\u{130}".match(/[[:punct:]]/).should be_nil
-    "\u{405}".match(/[[:punct:]]/).should be_nil
+    "\u{100}".match(/[[:punct:]]/).should == nil
+    "\u{130}".match(/[[:punct:]]/).should == nil
+    "\u{405}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode title-case characters with [[:punct:]]" do
-    "\u{1F88}".match(/[[:punct:]]/).should be_nil
-    "\u{1FAD}".match(/[[:punct:]]/).should be_nil
-    "\u{01C5}".match(/[[:punct:]]/).should be_nil
+    "\u{1F88}".match(/[[:punct:]]/).should == nil
+    "\u{1FAD}".match(/[[:punct:]]/).should == nil
+    "\u{01C5}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:punct:]]" do
-    "\u{0660}".match(/[[:punct:]]/).should be_nil
-    "\u{FF12}".match(/[[:punct:]]/).should be_nil
+    "\u{0660}".match(/[[:punct:]]/).should == nil
+    "\u{FF12}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:punct:]]" do
-    "\u{36F}".match(/[[:punct:]]/).should be_nil
+    "\u{36F}".match(/[[:punct:]]/).should == nil
   end
 
   it "matches Unicode Pc characters with [[:punct:]]" do
@@ -398,38 +398,38 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode format characters with [[:punct:]]" do
-    "\u{2060}".match(/[[:punct:]]/).should be_nil
+    "\u{2060}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:punct:]]" do
-    "\u{E001}".match(/[[:punct:]]/).should be_nil
+    "\u{E001}".match(/[[:punct:]]/).should == nil
   end
 
   it "doesn't match Unicode lowercase letter characters with [[:space:]]" do
-    "\u{FF41}".match(/[[:space:]]/).should be_nil
-    "\u{1D484}".match(/[[:space:]]/).should be_nil
-    "\u{E8}".match(/[[:space:]]/).should be_nil
+    "\u{FF41}".match(/[[:space:]]/).should == nil
+    "\u{1D484}".match(/[[:space:]]/).should == nil
+    "\u{E8}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode uppercase letter characters with [[:space:]]" do
-    "\u{100}".match(/[[:space:]]/).should be_nil
-    "\u{130}".match(/[[:space:]]/).should be_nil
-    "\u{405}".match(/[[:space:]]/).should be_nil
+    "\u{100}".match(/[[:space:]]/).should == nil
+    "\u{130}".match(/[[:space:]]/).should == nil
+    "\u{405}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode title-case characters with [[:space:]]" do
-    "\u{1F88}".match(/[[:space:]]/).should be_nil
-    "\u{1FAD}".match(/[[:space:]]/).should be_nil
-    "\u{01C5}".match(/[[:space:]]/).should be_nil
+    "\u{1F88}".match(/[[:space:]]/).should == nil
+    "\u{1FAD}".match(/[[:space:]]/).should == nil
+    "\u{01C5}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:space:]]" do
-    "\u{0660}".match(/[[:space:]]/).should be_nil
-    "\u{FF12}".match(/[[:space:]]/).should be_nil
+    "\u{0660}".match(/[[:space:]]/).should == nil
+    "\u{FF12}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:space:]]" do
-    "\u{36F}".match(/[[:space:]]/).should be_nil
+    "\u{36F}".match(/[[:space:]]/).should == nil
   end
 
   it "matches Unicode Zs characters with [[:space:]]" do
@@ -445,17 +445,17 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode format characters with [[:space:]]" do
-    "\u{2060}".match(/[[:space:]]/).should be_nil
+    "\u{2060}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:space:]]" do
-    "\u{E001}".match(/[[:space:]]/).should be_nil
+    "\u{E001}".match(/[[:space:]]/).should == nil
   end
 
   it "doesn't match Unicode lowercase characters with [[:upper:]]" do
-    "\u{FF41}".match(/[[:upper:]]/).should be_nil
-    "\u{1D484}".match(/[[:upper:]]/).should be_nil
-    "\u{E8}".match(/[[:upper:]]/).should be_nil
+    "\u{FF41}".match(/[[:upper:]]/).should == nil
+    "\u{1D484}".match(/[[:upper:]]/).should == nil
+    "\u{E8}".match(/[[:upper:]]/).should == nil
   end
 
   it "matches Unicode uppercase characters with [[:upper:]]" do
@@ -465,40 +465,40 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode title-case characters with [[:upper:]]" do
-    "\u{1F88}".match(/[[:upper:]]/).should be_nil
-    "\u{1FAD}".match(/[[:upper:]]/).should be_nil
-    "\u{01C5}".match(/[[:upper:]]/).should be_nil
+    "\u{1F88}".match(/[[:upper:]]/).should == nil
+    "\u{1FAD}".match(/[[:upper:]]/).should == nil
+    "\u{01C5}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode digits with [[:upper:]]" do
-    "\u{0660}".match(/[[:upper:]]/).should be_nil
-    "\u{FF12}".match(/[[:upper:]]/).should be_nil
+    "\u{0660}".match(/[[:upper:]]/).should == nil
+    "\u{FF12}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:upper:]]" do
-    "\u{36F}".match(/[[:upper:]]/).should be_nil
+    "\u{36F}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:upper:]]" do
-    "\u{3F}".match(/[[:upper:]]/).should be_nil
+    "\u{3F}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:upper:]]" do
-    "\u{16}".match(/[[:upper:]]/).should be_nil
+    "\u{16}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode format characters with [[:upper:]]" do
-    "\u{2060}".match(/[[:upper:]]/).should be_nil
+    "\u{2060}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:upper:]]" do
-    "\u{E001}".match(/[[:upper:]]/).should be_nil
+    "\u{E001}".match(/[[:upper:]]/).should == nil
   end
 
   it "doesn't match Unicode letter characters [^a-fA-F] with [[:xdigit:]]" do
-    "à".match(/[[:xdigit:]]/).should be_nil
-    "g".match(/[[:xdigit:]]/).should be_nil
-    "X".match(/[[:xdigit:]]/).should be_nil
+    "à".match(/[[:xdigit:]]/).should == nil
+    "g".match(/[[:xdigit:]]/).should == nil
+    "X".match(/[[:xdigit:]]/).should == nil
   end
 
   it "matches Unicode letter characters [a-fA-F] with [[:xdigit:]]" do
@@ -507,28 +507,28 @@ describe "Regexp with character classes" do
   end
 
   it "doesn't match Unicode digits [^0-9] with [[:xdigit:]]" do
-    "\u{0660}".match(/[[:xdigit:]]/).should be_nil
-    "\u{FF12}".match(/[[:xdigit:]]/).should be_nil
+    "\u{0660}".match(/[[:xdigit:]]/).should == nil
+    "\u{FF12}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "doesn't match Unicode marks with [[:xdigit:]]" do
-    "\u{36F}".match(/[[:xdigit:]]/).should be_nil
+    "\u{36F}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "doesn't match Unicode punctuation characters with [[:xdigit:]]" do
-    "\u{3F}".match(/[[:xdigit:]]/).should be_nil
+    "\u{3F}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:xdigit:]]" do
-    "\u{16}".match(/[[:xdigit:]]/).should be_nil
+    "\u{16}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "doesn't match Unicode format characters with [[:xdigit:]]" do
-    "\u{2060}".match(/[[:xdigit:]]/).should be_nil
+    "\u{2060}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:xdigit:]]" do
-    "\u{E001}".match(/[[:xdigit:]]/).should be_nil
+    "\u{E001}".match(/[[:xdigit:]]/).should == nil
   end
 
   it "matches Unicode lowercase characters with [[:word:]]" do
@@ -562,23 +562,30 @@ describe "Regexp with character classes" do
     "\u{16EE}".match(/[[:word:]]/).to_a.should == ["\u{16EE}"]
   end
 
+  ruby_bug "#19417", ""..."3.4.6" do
+    it "matches Unicode join control characters with [[:word:]]" do
+      "\u{200C}".match(/[[:word:]]/).to_a.should == ["\u{200C}"]
+      "\u{200D}".match(/[[:word:]]/).to_a.should == ["\u{200D}"]
+    end
+  end
+
   it "doesn't match Unicode No characters with [[:word:]]" do
-    "\u{17F0}".match(/[[:word:]]/).should be_nil
+    "\u{17F0}".match(/[[:word:]]/).should == nil
   end
   it "doesn't match Unicode punctuation characters with [[:word:]]" do
-    "\u{3F}".match(/[[:word:]]/).should be_nil
+    "\u{3F}".match(/[[:word:]]/).should == nil
   end
 
   it "doesn't match Unicode control characters with [[:word:]]" do
-    "\u{16}".match(/[[:word:]]/).should be_nil
+    "\u{16}".match(/[[:word:]]/).should == nil
   end
 
   it "doesn't match Unicode format characters with [[:word:]]" do
-    "\u{2060}".match(/[[:word:]]/).should be_nil
+    "\u{2060}".match(/[[:word:]]/).should == nil
   end
 
   it "doesn't match Unicode private-use characters with [[:word:]]" do
-    "\u{E001}".match(/[[:word:]]/).should be_nil
+    "\u{E001}".match(/[[:word:]]/).should == nil
   end
 
   it "matches unicode named character properties" do
@@ -609,6 +616,15 @@ describe "Regexp with character classes" do
     "루비(Ruby)".match(/\p{Hangul}+/u).to_a.should == ["루비"]
   end
 
+  it "supports negated property condition" do
+    "a".match(eval("/\P{L}/")).should == nil
+    "1".match(eval("/\P{N}/")).should == nil
+  end
+
+  it "raises a RegexpError for an unterminated unicode property" do
+    -> { Regexp.new('\p{') }.should.raise(RegexpError)
+  end
+
   it "supports \\X (unicode 9.0 with UTR #51 workarounds)" do
     # simple emoji without any fancy modifier or ZWJ
     /\X/.match("\u{1F98A}").to_a.should == ["🦊"]
diff --git a/spec/ruby/language/regexp/empty_checks_spec.rb b/spec/ruby/language/regexp/empty_checks_spec.rb
new file mode 100644
index 0000000000..391e65b003
--- /dev/null
+++ b/spec/ruby/language/regexp/empty_checks_spec.rb
@@ -0,0 +1,135 @@
+require_relative '../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "empty checks in Regexps" do
+
+  it "allow extra empty iterations" do
+    /()?/.match("").to_a.should == ["", ""]
+    /(a*)?/.match("").to_a.should == ["", ""]
+    /(a*)*/.match("").to_a.should == ["", ""]
+    # The bounds are high to avoid DFA-based matchers in implementations
+    # and to check backtracking behavior.
+    /(?:a|()){500,1000}/.match("a" * 500).to_a.should == ["a" * 500, ""]
+
+    # Variations with non-greedy loops.
+    /()??/.match("").to_a.should == ["", nil]
+    /(a*?)?/.match("").to_a.should == ["", ""]
+    /(a*)??/.match("").to_a.should == ["", nil]
+    /(a*?)??/.match("").to_a.should == ["", nil]
+    /(a*?)*/.match("").to_a.should == ["", ""]
+    /(a*)*?/.match("").to_a.should == ["", nil]
+    /(a*?)*?/.match("").to_a.should == ["", nil]
+  end
+
+  it "allow empty iterations in the middle of a loop" do
+    # One empty iteration between a's and b's.
+    /(a|\2b|())*/.match("aaabbb").to_a.should == ["aaabbb", "", ""]
+    /(a|\2b|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", ""]
+
+    # Two empty iterations between a's and b's.
+    /(a|\2b|\3()|())*/.match("aaabbb").to_a.should == ["aaabbb", "", "", ""]
+    /(a|\2b|\3()|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", nil, ""]
+
+    # Check that the empty iteration correctly updates the loop counter.
+    /(a|\2b|()){20,24}/.match("a" * 20 + "b" * 5).to_a.should == ["a" * 20 + "b" * 3, "b", ""]
+
+    # Variations with non-greedy loops.
+    /(a|\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", ""]
+    /(a|\2b|\3()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\2b|\3()|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", nil, ""]
+    /(a|\2b|()){20,24}/.match("a" * 20 + "b" * 5).to_a.should == ["a" * 20 + "b" * 3, "b", ""]
+  end
+
+  it "make the Regexp proceed past the quantified expression on failure" do
+    # If the contents of the ()* quantified group are empty (i.e., they fail
+    # the empty check), the loop will abort. It will not try to backtrack
+    # and try other alternatives (e.g. matching the "a") like in other Regexp
+    # dialects such as ECMAScript.
+    /(?:|a)*/.match("aaa").to_a.should == [""]
+    /(?:()|a)*/.match("aaa").to_a.should == ["", ""]
+    /(|a)*/.match("aaa").to_a.should == ["", ""]
+    /(()|a)*/.match("aaa").to_a.should == ["", "", ""]
+
+    # Same expressions, but with backreferences, to force the use of non-DFA-based
+    # engines.
+    /()\1(?:|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(()|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+
+    # Variations with other zero-width contents of the quantified
+    # group: backreferences, capture groups, lookarounds
+    /()(?:\1|a)*/.match("aaa").to_a.should == ["", ""]
+    /()(?:()\1|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(?:(\1)|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(?:\1()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(\1|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(()\1|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+    /()((\1)|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+    /()(\1()|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+
+    /(?:(?=a)|a)*/.match("aaa").to_a.should == [""]
+    /(?:(?=a)()|a)*/.match("aaa").to_a.should == ["", ""]
+    /(?:()(?=a)|a)*/.match("aaa").to_a.should == ["", ""]
+    /(?:((?=a))|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(?:()(?=a)|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(?:((?=a))|a)*/.match("aaa").to_a.should == ["", "", ""]
+
+    # Variations with non-greedy loops.
+    /(?:|a)*?/.match("aaa").to_a.should == [""]
+    /(?:()|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(()|a)*?/.match("aaa").to_a.should == ["", nil, nil]
+
+    /()\1(?:|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(()|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+
+    /()(?:\1|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()(?:()\1|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(?:(\1)|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(?:\1()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(\1|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(()\1|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+    /()((\1)|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+    /()(\1()|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+
+    /(?:(?=a)|a)*?/.match("aaa").to_a.should == [""]
+    /(?:(?=a)()|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(?:()(?=a)|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(?:((?=a))|a)*?/.match("aaa").to_a.should == ["", nil]
+    /()\1(?:(?=a)|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(?:()(?=a)|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(?:((?=a))|a)*?/.match("aaa").to_a.should == ["", "", nil]
+  end
+
+  it "shouldn't cause the Regexp parser to get stuck in a loop" do
+    /(|a|\2b|())*/.match("aaabbb").to_a.should == ["", "", nil]
+    /(a||\2b|())*/.match("aaabbb").to_a.should == ["aaa", "", nil]
+    /(a|\2b||())*/.match("aaabbb").to_a.should == ["aaa", "", nil]
+    /(a|\2b|()|)*/.match("aaabbb").to_a.should == ["aaabbb", "", ""]
+    /(()|a|\3b|())*/.match("aaabbb").to_a.should == ["", "", "", nil]
+    /(a|()|\3b|())*/.match("aaabbb").to_a.should == ["aaa", "", "", nil]
+    /(a|\2b|()|())*/.match("aaabbb").to_a.should == ["aaabbb", "", "", nil]
+    /(a|\3b|()|())*/.match("aaabbb").to_a.should == ["aaa", "", "", nil]
+    /(a|()|())*/.match("aaa").to_a.should == ["aaa", "", "", nil]
+    /^(()|a|())*$/.match("aaa").to_a.should == ["aaa", "", "", nil]
+
+    # Variations with non-greedy loops.
+    /(|a|\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a||\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b||())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b|()|)*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(()|a|\3b|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|()|\3b|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\2b|()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\3b|()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|()|())*?/.match("aaa").to_a.should == ["", nil, nil, nil]
+    /^(()|a|())*?$/.match("aaa").to_a.should == ["aaa", "a", "", nil]
+  end
+end
diff --git a/spec/ruby/language/regexp/encoding_spec.rb b/spec/ruby/language/regexp/encoding_spec.rb
index dce64a4753..81e845af0c 100644
--- a/spec/ruby/language/regexp/encoding_spec.rb
+++ b/spec/ruby/language/regexp/encoding_spec.rb
@@ -1,21 +1,21 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "Regexps with encoding modifiers" do
   it "supports /e (EUC encoding)" do
-    match = /./e.match("\303\251".force_encoding(Encoding::EUC_JP))
-    match.to_a.should == ["\303\251".force_encoding(Encoding::EUC_JP)]
+    match = /./e.match("\303\251".dup.force_encoding(Encoding::EUC_JP))
+    match.to_a.should == ["\303\251".dup.force_encoding(Encoding::EUC_JP)]
   end
 
   it "supports /e (EUC encoding) with interpolation" do
-    match = /#{/./}/e.match("\303\251".force_encoding(Encoding::EUC_JP))
-    match.to_a.should == ["\303\251".force_encoding(Encoding::EUC_JP)]
+    match = /#{/./}/e.match("\303\251".dup.force_encoding(Encoding::EUC_JP))
+    match.to_a.should == ["\303\251".dup.force_encoding(Encoding::EUC_JP)]
   end
 
   it "supports /e (EUC encoding) with interpolation /o" do
-    match = /#{/./}/e.match("\303\251".force_encoding(Encoding::EUC_JP))
-    match.to_a.should == ["\303\251".force_encoding(Encoding::EUC_JP)]
+    match = /#{/./}/e.match("\303\251".dup.force_encoding(Encoding::EUC_JP))
+    match.to_a.should == ["\303\251".dup.force_encoding(Encoding::EUC_JP)]
   end
 
   it 'uses EUC-JP as /e encoding' do
@@ -38,10 +38,22 @@ describe "Regexps with encoding modifiers" do
     /#{/./}/n.match("\303\251").to_a.should == ["\303"]
   end
 
+  it "warns when using /n with a match string with non-ASCII characters and an encoding other than ASCII-8BIT" do
+    -> {
+      eval <<~RUBY
+      /./n.match("\303\251".dup.force_encoding('utf-8'))
+      RUBY
+    }.should complain(%r{historical binary regexp match /.../n against UTF-8 string})
+  end
+
   it 'uses US-ASCII as /n encoding if all chars are 7-bit' do
     /./n.encoding.should == Encoding::US_ASCII
   end
 
+  it 'uses BINARY when is not initialized' do
+    Regexp.allocate.encoding.should == Encoding::BINARY
+  end
+
   it 'uses BINARY as /n encoding if not all chars are 7-bit' do
     /\xFF/n.encoding.should == Encoding::BINARY
   end
@@ -55,18 +67,18 @@ describe "Regexps with encoding modifiers" do
   end
 
   it "supports /s (Windows_31J encoding)" do
-    match = /./s.match("\303\251".force_encoding(Encoding::Windows_31J))
-    match.to_a.should == ["\303".force_encoding(Encoding::Windows_31J)]
+    match = /./s.match("\303\251".dup.force_encoding(Encoding::Windows_31J))
+    match.to_a.should == ["\303".dup.force_encoding(Encoding::Windows_31J)]
   end
 
   it "supports /s (Windows_31J encoding) with interpolation" do
-    match = /#{/./}/s.match("\303\251".force_encoding(Encoding::Windows_31J))
-    match.to_a.should == ["\303".force_encoding(Encoding::Windows_31J)]
+    match = /#{/./}/s.match("\303\251".dup.force_encoding(Encoding::Windows_31J))
+    match.to_a.should == ["\303".dup.force_encoding(Encoding::Windows_31J)]
   end
 
   it "supports /s (Windows_31J encoding) with interpolation and /o" do
-    match = /#{/./}/s.match("\303\251".force_encoding(Encoding::Windows_31J))
-    match.to_a.should == ["\303".force_encoding(Encoding::Windows_31J)]
+    match = /#{/./}/s.match("\303\251".dup.force_encoding(Encoding::Windows_31J))
+    match.to_a.should == ["\303".dup.force_encoding(Encoding::Windows_31J)]
   end
 
   it 'uses Windows-31J as /s encoding' do
@@ -78,15 +90,15 @@ describe "Regexps with encoding modifiers" do
   end
 
   it "supports /u (UTF8 encoding)" do
-    /./u.match("\303\251".force_encoding('utf-8')).to_a.should == ["\u{e9}"]
+    /./u.match("\303\251".dup.force_encoding('utf-8')).to_a.should == ["\u{e9}"]
   end
 
   it "supports /u (UTF8 encoding) with interpolation" do
-    /#{/./}/u.match("\303\251".force_encoding('utf-8')).to_a.should == ["\u{e9}"]
+    /#{/./}/u.match("\303\251".dup.force_encoding('utf-8')).to_a.should == ["\u{e9}"]
   end
 
   it "supports /u (UTF8 encoding) with interpolation and /o" do
-    /#{/./}/u.match("\303\251".force_encoding('utf-8')).to_a.should == ["\u{e9}"]
+    /#{/./}/u.match("\303\251".dup.force_encoding('utf-8')).to_a.should == ["\u{e9}"]
   end
 
   it 'uses UTF-8 as /u encoding' do
@@ -100,4 +112,41 @@ describe "Regexps with encoding modifiers" do
   it "selects last of multiple encoding specifiers" do
     /foo/ensuensuens.should == /foo/s
   end
+
+  it "raises Encoding::CompatibilityError when trying match against different encodings" do
+    -> { /\A[[:space:]]*\z/.match(" ".encode("UTF-16LE")) }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "raises Encoding::CompatibilityError when trying match? against different encodings" do
+    -> { /\A[[:space:]]*\z/.match?(" ".encode("UTF-16LE")) }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "raises Encoding::CompatibilityError when trying =~ against different encodings" do
+    -> { /\A[[:space:]]*\z/ =~ " ".encode("UTF-16LE") }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "raises Encoding::CompatibilityError when the regexp has a fixed, non-ASCII-compatible encoding" do
+    -> { Regexp.new("".dup.force_encoding("UTF-16LE"), Regexp::FIXEDENCODING) =~ " ".encode("UTF-8") }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "raises Encoding::CompatibilityError when the regexp has a fixed encoding and the match string has non-ASCII characters" do
+    -> { Regexp.new("".dup.force_encoding("US-ASCII"), Regexp::FIXEDENCODING) =~ "\303\251".dup.force_encoding('UTF-8') }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "raises ArgumentError when trying to match a broken String" do
+    s = "\x80".dup.force_encoding('UTF-8')
+    -> { s =~ /./ }.should.raise(ArgumentError, "invalid byte sequence in UTF-8")
+  end
+
+  it "computes the Regexp Encoding for each interpolated Regexp instance" do
+    make_regexp = -> str { /#{str}/ }
+
+    r = make_regexp.call("été".dup.force_encoding(Encoding::UTF_8))
+    r.should.fixed_encoding?
+    r.encoding.should == Encoding::UTF_8
+
+    r = make_regexp.call("abc".dup.force_encoding(Encoding::UTF_8))
+    r.should_not.fixed_encoding?
+    r.encoding.should == Encoding::US_ASCII
+  end
 end
diff --git a/spec/ruby/language/regexp/escapes_spec.rb b/spec/ruby/language/regexp/escapes_spec.rb
index 14e1424d47..4a0e611540 100644
--- a/spec/ruby/language/regexp/escapes_spec.rb
+++ b/spec/ruby/language/regexp/escapes_spec.rb
@@ -1,9 +1,11 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../../spec_helper'
 require_relative '../fixtures/classes'
 
+# TODO: synchronize with spec/core/regexp/new_spec.rb -
+#       escaping is also tested there
 describe "Regexps with escape characters" do
-  it "they're supported" do
+  it "supports escape sequences" do
     /\t/.match("\t").to_a.should == ["\t"] # horizontal tab
     /\v/.match("\v").to_a.should == ["\v"] # vertical tab
     /\n/.match("\n").to_a.should == ["\n"] # newline
@@ -15,9 +17,7 @@ describe "Regexps with escape characters" do
     # \nnn         octal char            (encoded byte value)
   end
 
-  it "support quoting meta-characters via escape sequence" do
-    /\\/.match("\\").to_a.should == ["\\"]
-    /\//.match("/").to_a.should == ["/"]
+  it "supports quoting meta-characters via escape sequence" do
     # parenthesis, etc
     /\(/.match("(").to_a.should == ["("]
     /\)/.match(")").to_a.should == [")"]
@@ -25,6 +25,8 @@ describe "Regexps with escape characters" do
     /\]/.match("]").to_a.should == ["]"]
     /\{/.match("{").to_a.should == ["{"]
     /\}/.match("}").to_a.should == ["}"]
+    /\</.match("<").to_a.should == ["<"]
+    /\>/.match(">").to_a.should == [">"]
     # alternation separator
     /\|/.match("|").to_a.should == ["|"]
     # quantifiers
@@ -37,23 +39,93 @@ describe "Regexps with escape characters" do
     /\$/.match("$").to_a.should == ["$"]
   end
 
+  it "supports quoting meta-characters via escape sequence when used as a terminator" do
+    # parenthesis, etc
+    # %r[[, %r((, etc literals - are forbidden
+    %r(\().match("(").to_a.should == ["("]
+    %r(\)).match(")").to_a.should == [")"]
+    %r)\().match("(").to_a.should == ["("]
+    %r)\)).match(")").to_a.should == [")"]
+
+    %r[\[].match("[").to_a.should == ["["]
+    %r[\]].match("]").to_a.should == ["]"]
+    %r]\[].match("[").to_a.should == ["["]
+    %r]\]].match("]").to_a.should == ["]"]
+
+    %r{\{}.match("{").to_a.should == ["{"]
+    %r{\}}.match("}").to_a.should == ["}"]
+    %r}\{}.match("{").to_a.should == ["{"]
+    %r}\}}.match("}").to_a.should == ["}"]
+
+    %r<\<>.match("<").to_a.should == ["<"]
+    %r<\>>.match(">").to_a.should == [">"]
+    %r>\<>.match("<").to_a.should == ["<"]
+    %r>\>>.match(">").to_a.should == [">"]
+
+    # alternation separator
+    %r|\||.match("|").to_a.should == ["|"]
+    # quantifiers
+    %r?\??.match("?").to_a.should == ["?"]
+    %r.\...match(".").to_a.should == ["."]
+    %r*\**.match("*").to_a.should == ["*"]
+    %r+\++.match("+").to_a.should == ["+"]
+    # line anchors
+    %r^\^^.match("^").to_a.should == ["^"]
+    %r$\$$.match("$").to_a.should == ["$"]
+  end
+
+  it "supports quoting non-meta-characters via escape sequence when used as a terminator" do
+    non_meta_character_terminators = [
+      '!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`', '/', '=', '~'
+    ]
+
+    non_meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.match(c).to_a.should == [c]
+    end
+  end
+
+  it "does not change semantics of escaped non-meta-character when used as a terminator" do
+    all_terminators = [*("!".."/"), *(":".."@"), *("[".."`"), *("{".."~")]
+    meta_character_terminators = ["$", "^", "*", "+", ".", "?", "|", "}", ")", ">", "]"]
+    special_cases = ['(', '{', '[', '<', '\\']
+
+    # it should be equivalent to
+    #   [ '!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`', '/', '=', '~' ]
+    non_meta_character_terminators = all_terminators - meta_character_terminators - special_cases
+
+    non_meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.should == /#{c}/
+    end
+  end
+
+  it "does not change semantics of escaped meta-character when used as a terminator" do
+    meta_character_terminators = ["$", "^", "*", "+", ".", "?", "|", "}", ")", ">", "]"]
+
+    meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.should == eval("/\\#{c}/")
+    end
+  end
+
   it "allows any character to be escaped" do
     /\y/.match("y").to_a.should == ["y"]
   end
 
-  it "support \\x (hex characters)" do
+  it "supports \\x (hex characters)" do
     /\xA/.match("\nxyz").to_a.should == ["\n"]
     /\x0A/.match("\n").to_a.should == ["\n"]
-    /\xAA/.match("\nA").should be_nil
+    /\xAA/.match("\nA").should == nil
     /\x0AA/.match("\nA").to_a.should == ["\nA"]
     /\xAG/.match("\nG").to_a.should == ["\nG"]
     # Non-matches
-    -> { eval('/\xG/') }.should raise_error(SyntaxError)
+    -> { eval('/\xG/') }.should.raise(SyntaxError)
 
     # \x{7HHHHHHH} wide hexadecimal char (character code point value)
   end
 
-  it "support \\c (control characters)" do
+  it "supports \\c (control characters)" do
     #/\c \c@\c`/.match("\00\00\00").to_a.should == ["\00\00\00"]
     /\c#\cc\cC/.match("\03\03\03").to_a.should == ["\03\03\03"]
     /\c'\cG\cg/.match("\a\a\a").to_a.should == ["\a\a\a"]
@@ -64,18 +136,34 @@ describe "Regexps with escape characters" do
     /\c,\cL\cl/.match("\f\f\f").to_a.should == ["\f\f\f"]
     /\c-\cM\cm/.match("\r\r\r").to_a.should == ["\r\r\r"]
 
-    /\cJ/.match("\r").should be_nil
+    /\cJ/.match("\r").should == nil
 
     # Parsing precedence
     /\cJ+/.match("\n\n").to_a.should == ["\n\n"] # Quantifiers apply to entire escape sequence
     /\\cJ/.match("\\cJ").to_a.should == ["\\cJ"]
-    -> { eval('/[abc\x]/') }.should raise_error(SyntaxError) # \x is treated as a escape sequence even inside a character class
+    -> { eval('/[abc\x]/') }.should.raise(SyntaxError) # \x is treated as a escape sequence even inside a character class
     # Syntax error
-    -> { eval('/\c/') }.should raise_error(SyntaxError)
+    -> { eval('/\c/') }.should.raise(SyntaxError)
 
     # \cx          control char          (character code point value)
     # \C-x         control char          (character code point value)
     # \M-x         meta  (x|0x80)        (character code point value)
     # \M-\C-x      meta control char     (character code point value)
   end
+
+  it "handles three digit octal escapes starting with 0" do
+    /[\000-\b]/.match("\x00")[0].should == "\x00"
+  end
+
+  it "handles control escapes with \\C-x syntax" do
+    /\C-*\C-J\C-j/.match("\n\n\n")[0].should == "\n\n\n"
+  end
+
+  it "supports the \\K keep operator" do
+    /a\Kb/.match("ab")[0].should == "b"
+  end
+
+  it "supports the \\R line break escape" do
+    /\R/.match("\n")[0].should == "\n"
+  end
 end
diff --git a/spec/ruby/language/regexp/grouping_spec.rb b/spec/ruby/language/regexp/grouping_spec.rb
index 8806d06746..80ad7460da 100644
--- a/spec/ruby/language/regexp/grouping_spec.rb
+++ b/spec/ruby/language/regexp/grouping_spec.rb
@@ -12,7 +12,7 @@ describe "Regexps with grouping" do
   end
 
   it "raises a SyntaxError when parentheses aren't balanced" do
-   -> { eval "/(hay(st)ack/" }.should raise_error(SyntaxError)
+    -> { eval "/(hay(st)ack/" }.should.raise(SyntaxError)
   end
 
   it "supports (?: ) (non-capturing group)" do
@@ -20,4 +20,44 @@ describe "Regexps with grouping" do
     # Parsing precedence
     /(?:xdigit:)/.match("xdigit:").to_a.should == ["xdigit:"]
   end
+
+  it "group names cannot start with digits or minus" do
+    -> { Regexp.new("(?<1a>a)") }.should.raise(RegexpError)
+    -> { Regexp.new("(?<-a>a)") }.should.raise(RegexpError)
+  end
+
+  it "ignore capture groups in line comments" do
+    /^
+     (a) # there is a capture group on this line
+     b   # there is no capture group on this line (not even here)
+     $/x.match("ab").to_a.should == [ "ab", "a" ]
+  end
+
+  it "does not consider # inside a character class as a comment" do
+    # From https://github.com/rubocop/rubocop/blob/39fcf1c568/lib/rubocop/cop/utils/format_string.rb#L18
+    regexp = /
+        % (?<type>%) # line comment
+      | % (?<flags>(?-mix:[ #0+-]|(?-mix:(\d+)\$))*) (?#group comment)
+        (?:
+          (?: (?-mix:(?<width>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:\.(?<precision>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:<(?<name>\w+)>)?
+            | (?-mix:(?<width>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:<(?<name>\w+)>) (?-mix:\.(?<precision>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))?
+            | (?-mix:<(?<name>\w+)>) (?<more_flags>(?-mix:[ #0+-]|(?-mix:(\d+)\$))*) (?-mix:(?<width>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:\.(?<precision>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))?
+          ) (?-mix:(?<type>[bBdiouxXeEfgGaAcps]))
+          | (?-mix:(?<width>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:\.(?<precision>(?-mix:\d+|(?-mix:\*(?-mix:(\d+)\$)?))))? (?-mix:\{(?<name>\w+)\})
+        )
+    /x
+    regexp.named_captures.should == {
+      "type" => [1, 13],
+      "flags" => [2],
+      "width" => [3, 6, 11, 14],
+      "precision" => [4, 8, 12, 15],
+      "name" => [5, 7, 9, 16],
+      "more_flags" => [10]
+    }
+    match = regexp.match("%6.3f")
+    match[:width].should == '6'
+    match[:precision].should == '3'
+    match[:type].should == 'f'
+    match.to_a.should == [ "%6.3f", nil, "", "6", "3"] + [nil] * 8 + ["f"] + [nil] * 3
+  end
 end
diff --git a/spec/ruby/language/regexp/interpolation_spec.rb b/spec/ruby/language/regexp/interpolation_spec.rb
index ed0b724763..f771d0a395 100644
--- a/spec/ruby/language/regexp/interpolation_spec.rb
+++ b/spec/ruby/language/regexp/interpolation_spec.rb
@@ -36,14 +36,14 @@ describe "Regexps with interpolation" do
 
   it "gives precedence to escape sequences over substitution" do
     str = "J"
-    /\c#{str}/.to_s.should == '(?-mix:\c#' + '{str})'
+    /\c#{str}/.to_s.should.include?('{str}')
   end
 
   it "throws RegexpError for malformed interpolation" do
     s = ""
-    -> { /(#{s}/ }.should raise_error(RegexpError)
+    -> { /(#{s}/ }.should.raise(RegexpError)
     s = "("
-    -> { /#{s}/ }.should raise_error(RegexpError)
+    -> { /#{s}/ }.should.raise(RegexpError)
   end
 
   it "allows interpolation in extended mode" do
diff --git a/spec/ruby/language/regexp/modifiers_spec.rb b/spec/ruby/language/regexp/modifiers_spec.rb
index 9f3cf8acf8..c96fbfa983 100644
--- a/spec/ruby/language/regexp/modifiers_spec.rb
+++ b/spec/ruby/language/regexp/modifiers_spec.rb
@@ -8,7 +8,7 @@ describe "Regexps with modifiers" do
 
   it "supports /m (multiline)" do
     /foo.bar/m.match("foo\nbar").to_a.should == ["foo\nbar"]
-    /foo.bar/.match("foo\nbar").should be_nil
+    /foo.bar/.match("foo\nbar").should == nil
   end
 
   it "supports /x (extended syntax)" do
@@ -36,7 +36,7 @@ describe "Regexps with modifiers" do
     /foo/imox.match("foo").to_a.should == ["foo"]
     /foo/imoximox.match("foo").to_a.should == ["foo"]
 
-    -> { eval('/foo/a') }.should raise_error(SyntaxError)
+    -> { eval('/foo/a') }.should.raise(SyntaxError)
   end
 
   it "supports (?~) (absent operator)" do
@@ -46,57 +46,57 @@ describe "Regexps with modifiers" do
 
   it "supports (?imx-imx) (inline modifiers)" do
     /(?i)foo/.match("FOO").to_a.should == ["FOO"]
-    /foo(?i)/.match("FOO").should be_nil
+    /foo(?i)/.match("FOO").should == nil
     # Interaction with /i
-    /(?-i)foo/i.match("FOO").should be_nil
+    /(?-i)foo/i.match("FOO").should == nil
     /foo(?-i)/i.match("FOO").to_a.should == ["FOO"]
     # Multiple uses
     /foo (?i)bar (?-i)baz/.match("foo BAR baz").to_a.should == ["foo BAR baz"]
-    /foo (?i)bar (?-i)baz/.match("foo BAR BAZ").should be_nil
+    /foo (?i)bar (?-i)baz/.match("foo BAR BAZ").should == nil
 
     /(?m)./.match("\n").to_a.should == ["\n"]
-    /.(?m)/.match("\n").should be_nil
+    /.(?m)/.match("\n").should == nil
     # Interaction with /m
-    /(?-m)./m.match("\n").should be_nil
+    /(?-m)./m.match("\n").should == nil
     /.(?-m)/m.match("\n").to_a.should == ["\n"]
     # Multiple uses
     /. (?m). (?-m)./.match(". \n .").to_a.should == [". \n ."]
-    /. (?m). (?-m)./.match(". \n \n").should be_nil
+    /. (?m). (?-m)./.match(". \n \n").should == nil
 
     /(?x) foo /.match("foo").to_a.should == ["foo"]
-    / foo (?x)/.match("foo").should be_nil
+    / foo (?x)/.match("foo").should == nil
     # Interaction with /x
-    /(?-x) foo /x.match("foo").should be_nil
+    /(?-x) foo /x.match("foo").should == nil
     / foo (?-x)/x.match("foo").to_a.should == ["foo"]
     # Multiple uses
     /( foo )(?x)( bar )(?-x)( baz )/.match(" foo bar baz ").to_a.should == [" foo bar baz ", " foo ", "bar", " baz "]
-    /( foo )(?x)( bar )(?-x)( baz )/.match(" foo barbaz").should be_nil
+    /( foo )(?x)( bar )(?-x)( baz )/.match(" foo barbaz").should == nil
 
     # Parsing
-    /(?i-i)foo/.match("FOO").should be_nil
+    /(?i-i)foo/.match("FOO").should == nil
     /(?ii)foo/.match("FOO").to_a.should == ["FOO"]
     /(?-)foo/.match("foo").to_a.should == ["foo"]
-    -> { eval('/(?o)/') }.should raise_error(SyntaxError)
+    -> { eval('/(?o)/') }.should.raise(SyntaxError)
   end
 
   it "supports (?imx-imx:expr) (scoped inline modifiers)" do
     /foo (?i:bar) baz/.match("foo BAR baz").to_a.should == ["foo BAR baz"]
-    /foo (?i:bar) baz/.match("foo BAR BAZ").should be_nil
-    /foo (?-i:bar) baz/i.match("foo BAR BAZ").should be_nil
+    /foo (?i:bar) baz/.match("foo BAR BAZ").should == nil
+    /foo (?-i:bar) baz/i.match("foo BAR BAZ").should == nil
 
     /. (?m:.) ./.match(". \n .").to_a.should == [". \n ."]
-    /. (?m:.) ./.match(". \n \n").should be_nil
-    /. (?-m:.) ./m.match("\n \n \n").should be_nil
+    /. (?m:.) ./.match(". \n \n").should == nil
+    /. (?-m:.) ./m.match("\n \n \n").should == nil
 
     /( foo )(?x: bar )( baz )/.match(" foo bar baz ").to_a.should == [" foo bar baz ", " foo ", " baz "]
-    /( foo )(?x: bar )( baz )/.match(" foo barbaz").should be_nil
+    /( foo )(?x: bar )( baz )/.match(" foo barbaz").should == nil
     /( foo )(?-x: bar )( baz )/x.match("foo bar baz").to_a.should == ["foo bar baz", "foo", "baz"]
 
     # Parsing
-    /(?i-i:foo)/.match("FOO").should be_nil
+    /(?i-i:foo)/.match("FOO").should == nil
     /(?ii:foo)/.match("FOO").to_a.should == ["FOO"]
     /(?-:)foo/.match("foo").to_a.should == ["foo"]
-    -> { eval('/(?o:)/') }.should raise_error(SyntaxError)
+    -> { eval('/(?o:)/') }.should.raise(SyntaxError)
   end
 
   it "supports . with /m" do
@@ -104,7 +104,7 @@ describe "Regexps with modifiers" do
     /./m.match("\n").to_a.should == ["\n"]
   end
 
-  it "supports ASII/Unicode modifiers" do
+  it "supports ASCII/Unicode modifiers" do
     eval('/(?a)[[:alpha:]]+/').match("a\u3042").to_a.should == ["a"]
     eval('/(?d)[[:alpha:]]+/').match("a\u3042").to_a.should == ["a\u3042"]
     eval('/(?u)[[:alpha:]]+/').match("a\u3042").to_a.should == ["a\u3042"]
diff --git a/spec/ruby/language/regexp/repetition_spec.rb b/spec/ruby/language/regexp/repetition_spec.rb
index 7bb767ccaf..f24323de5c 100644
--- a/spec/ruby/language/regexp/repetition_spec.rb
+++ b/spec/ruby/language/regexp/repetition_spec.rb
@@ -15,7 +15,7 @@ describe "Regexps with repetition" do
 
   it "supports + (1 or more of previous subexpression)" do
     /a+/.match("aaa").to_a.should == ["aaa"]
-    /a+/.match("bbb").should be_nil
+    /a+/.match("bbb").should == nil
     /<.+>/.match("<a>foo</a>").to_a.should == ["<a>foo</a>"] # it is greedy
   end
 
@@ -45,4 +45,94 @@ describe "Regexps with repetition" do
     /a?/.match("aaa").to_a.should == ["a"]
     /a?/.match("bbb").to_a.should == [""]
   end
+
+  it "handles incomplete range quantifiers" do
+    /a{}/.match("a{}")[0].should == "a{}"
+    /a{,}/.match("a{,}")[0].should == "a{,}"
+    /a{1/.match("a{1")[0].should == "a{1"
+    /a{1,2/.match("a{1,2")[0].should == "a{1,2"
+    /a{,5}/.match("aaa")[0].should == "aaa"
+  end
+
+  it "lets us use quantifiers on assertions" do
+    /a^?b/.match("ab")[0].should == "ab"
+    /a$?b/.match("ab")[0].should == "ab"
+    /a\A?b/.match("ab")[0].should == "ab"
+    /a\Z?b/.match("ab")[0].should == "ab"
+    /a\z?b/.match("ab")[0].should == "ab"
+    /a\G?b/.match("ab")[0].should == "ab"
+    /a\b?b/.match("ab")[0].should == "ab"
+    /a\B?b/.match("ab")[0].should == "ab"
+    /a(?=c)?b/.match("ab")[0].should == "ab"
+    /a(?!=b)?b/.match("ab")[0].should == "ab"
+    /a(?<=c)?b/.match("ab")[0].should == "ab"
+    /a(?<!a)?b/.match("ab")[0].should == "ab"
+  end
+
+  it "does not delete optional assertions" do
+    /(?=(a))?/.match("a").to_a.should == [ "", "a" ]
+  end
+
+  it "supports nested quantifiers" do
+    suppress_warning do
+      eval <<-RUBY
+      /a***/.match("aaa")[0].should == "aaa"
+
+      # a+?* should not be reduced, it should be equivalent to (a+?)*
+      # NB: the capture group prevents regex engines from reducing the two quantifiers
+      # https://bugs.ruby-lang.org/issues/17341
+      /a+?*/.match("")[0].should == ""
+      /(a+?)*/.match("")[0].should == ""
+
+      /a+?*/.match("a")[0].should == "a"
+      /(a+?)*/.match("a")[0].should == "a"
+
+      /a+?*/.match("aa")[0].should == "aa"
+      /(a+?)*/.match("aa")[0].should == "aa"
+
+      # a+?+ should not be reduced, it should be equivalent to (a+?)+
+      # https://bugs.ruby-lang.org/issues/17341
+      /a+?+/.match("").should == nil
+      /(a+?)+/.match("").should == nil
+
+      /a+?+/.match("a")[0].should == "a"
+      /(a+?)+/.match("a")[0].should == "a"
+
+      /a+?+/.match("aa")[0].should == "aa"
+      /(a+?)+/.match("aa")[0].should == "aa"
+
+      # both a**? and a+*? should be equivalent to (a+)??
+      # this quantifier would rather match nothing, but if that's not possible,
+      # it will greedily take everything
+      /a**?/.match("")[0].should == ""
+      /(a*)*?/.match("")[0].should == ""
+      /a+*?/.match("")[0].should == ""
+      /(a+)*?/.match("")[0].should == ""
+      /(a+)??/.match("")[0].should == ""
+
+      /a**?/.match("aaa")[0].should == ""
+      /(a*)*?/.match("aaa")[0].should == ""
+      /a+*?/.match("aaa")[0].should == ""
+      /(a+)*?/.match("aaa")[0].should == ""
+      /(a+)??/.match("aaa")[0].should == ""
+
+      /b.**?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.*)*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b.+*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.+)*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.+)??b/.match("baaabaaab")[0].should == "baaabaaab"
+      RUBY
+    end
+  end
+
+  it "treats ? after {n} quantifier as another quantifier, not as non-greedy marker" do
+    /a{2}?/.match("").to_a.should == [""]
+  end
+
+  it "matches zero-width capture groups in optional iterations of loops" do
+    /()?/.match("").to_a.should == ["", ""]
+    /(a*)?/.match("").to_a.should == ["", ""]
+    /(a*)*/.match("").to_a.should == ["", ""]
+    /(?:a|()){500,1000}/.match("a" * 500).to_a.should == ["a" * 500, ""]
+  end
 end
diff --git a/spec/ruby/language/regexp/subexpression_call_spec.rb b/spec/ruby/language/regexp/subexpression_call_spec.rb
new file mode 100644
index 0000000000..16b64cb327
--- /dev/null
+++ b/spec/ruby/language/regexp/subexpression_call_spec.rb
@@ -0,0 +1,50 @@
+require_relative '../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "Regexps with subexpression calls" do
+  it "allows numeric subexpression calls" do
+    /(a)\g<1>/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+
+  it "treats subexpression calls as distinct from simple back-references" do
+    # Back-references only match a string which is equal to the original captured string.
+    /(?<three_digits>[0-9]{3})-\k<three_digits>/.match("123-123")[0].should == "123-123"
+    /(?<three_digits>[0-9]{3})-\k<three_digits>/.match("123-456").should == nil
+    # However, subexpression calls reuse the previous expression and can match a different
+    # string.
+    /(?<three_digits>[0-9]{3})-\g<three_digits>/.match("123-456")[0].should == "123-456"
+  end
+
+  it "allows recursive subexpression calls" do
+    # This pattern matches well-nested parenthesized expression.
+    parens = /^ (?<parens>  (?: \( \g<parens> \) | [^()] )*  ) $/x
+    parens.match("((a)(b))c(d)")[0].should == "((a)(b))c(d)"
+    parens.match("((a)(b)c(d)").should == nil
+  end
+
+  it "allows access to back-references from the current level" do
+    # Using \\k<first_char-0> accesses the last value captured in first_char
+    # on the current stack level.
+    mirror = /^ (?<mirror> (?: (?<first_char>.) \g<mirror> \k<first_char-0> )? ) $/x
+    mirror.match("abccba")[0].should == "abccba"
+    mirror.match("abccbd").should == nil
+
+    # OTOH, using \\k<first_char> accesses the last value captured in first_char,
+    # regardless of the stack level. Therefore, it can't be used to implement
+    # the mirror language.
+    broken_mirror = /^ (?<mirror> (?: (?<first_char>.) \g<mirror> \k<first_char> )? ) $/x
+    broken_mirror.match("abccba").should == nil
+    # This matches because the 'c' is captured in first_char and that value is
+    # then used for all subsequent back-references, regardless of nesting.
+    broken_mirror.match("abcccc")[0].should == "abcccc"
+  end
+
+  it "allows + and - in group names and referential constructs that don't use levels, i.e. subexpression calls" do
+    /(?<a+>a)\g<a+>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a+b>a)\g<a+b>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a+1>a)\g<a+1>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a->a)\g<a->/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a-b>a)\g<a-b>/.match("aa").to_a.should == [ "aa", "a" ]
+    /(?<a-1>a)\g<a-1>/.match("aa").to_a.should == [ "aa", "a" ]
+  end
+end
diff --git a/spec/ruby/language/regexp_spec.rb b/spec/ruby/language/regexp_spec.rb
index 67c7c034e9..1452b01935 100644
--- a/spec/ruby/language/regexp_spec.rb
+++ b/spec/ruby/language/regexp_spec.rb
@@ -15,7 +15,11 @@ describe "Literal Regexps" do
   end
 
   it "yields a Regexp" do
-    /Hello/.should be_kind_of(Regexp)
+    /Hello/.should.is_a?(Regexp)
+  end
+
+  it "is frozen" do
+    /Hello/.should.frozen?
   end
 
   it "caches the Regexp object" do
@@ -23,11 +27,11 @@ describe "Literal Regexps" do
     2.times do |i|
       rs << /foo/
     end
-    rs[0].should equal(rs[1])
+    rs[0].should.equal?(rs[1])
   end
 
   it "throws SyntaxError for malformed literals" do
-    -> { eval('/(/') }.should raise_error(SyntaxError)
+    -> { eval('/(/') }.should.raise(SyntaxError)
   end
 
   #############################################################################
@@ -54,22 +58,22 @@ describe "Literal Regexps" do
 
   it "disallows first part of paired delimiters to be used as non-paired delimiters" do
     LanguageSpecs.paired_delimiters.each do |p0, p1|
-      -> { eval("%r#{p0} foo #{p0}") }.should raise_error(SyntaxError)
+      -> { eval("%r#{p0} foo #{p0}") }.should.raise(SyntaxError)
     end
   end
 
-  it "supports non-paired delimiters delimiters with %r" do
+  it "supports non-paired delimiters with %r" do
     LanguageSpecs.non_paired_delimiters.each do |c|
       eval("%r#{c} foo #{c}").should == / foo /
     end
   end
 
   it "disallows alphabets as non-paired delimiter with %r" do
-    -> { eval('%ra foo a') }.should raise_error(SyntaxError)
+    -> { eval('%ra foo a') }.should.raise(SyntaxError)
   end
 
   it "disallows spaces after %r and delimiter" do
-    -> { eval('%r !foo!') }.should raise_error(SyntaxError)
+    -> { eval('%r !foo!') }.should.raise(SyntaxError)
   end
 
   it "allows unescaped / to be used with %r" do
@@ -85,19 +89,18 @@ describe "Literal Regexps" do
     # Basic matching
     /./.match("foo").to_a.should == ["f"]
     # Basic non-matching
-    /./.match("").should be_nil
-    /./.match("\n").should be_nil
+    /./.match("").should == nil
+    /./.match("\n").should == nil
     /./.match("\0").to_a.should == ["\0"]
   end
 
-
   it "supports | (alternations)" do
     /a|b/.match("a").to_a.should == ["a"]
   end
 
   it "supports (?> ) (embedded subexpression)" do
     /(?>foo)(?>bar)/.match("foobar").to_a.should == ["foobar"]
-    /(?>foo*)obar/.match("foooooooobar").should be_nil # it is possessive
+    /(?>foo*)obar/.match("foooooooobar").should == nil # it is possessive
   end
 
   it "supports (?# )" do
@@ -109,6 +112,13 @@ describe "Literal Regexps" do
     /foo.(?<=\d)/.match("fooA foo1").to_a.should == ["foo1"]
   end
 
+  ruby_bug "#13671", ""..."4.0" do # https://bugs.ruby-lang.org/issues/13671
+    it "handles a lookbehind with ss characters" do
+      r =  Regexp.new("(?<!dss)", Regexp::IGNORECASE)
+      r.should =~ "✨"
+    end
+  end
+
   it "supports (?<! ) (negative lookbehind)" do
     /foo.(?<!\d)/.match("foo1 fooA").to_a.should == ["fooA"]
   end
@@ -125,9 +135,9 @@ describe "Literal Regexps" do
   it "supports possessive quantifiers" do
     /fooA++bar/.match("fooAAAbar").to_a.should == ["fooAAAbar"]
 
-    /fooA++Abar/.match("fooAAAbar").should be_nil
-    /fooA?+Abar/.match("fooAAAbar").should be_nil
-    /fooA*+Abar/.match("fooAAAbar").should be_nil
+    /fooA++Abar/.match("fooAAAbar").should == nil
+    /fooA?+Abar/.match("fooAAAbar").should == nil
+    /fooA*+Abar/.match("fooAAAbar").should == nil
   end
 
   it "supports conditional regular expressions with positional capture groups" do
@@ -148,26 +158,6 @@ describe "Literal Regexps" do
     pattern.should_not =~ 'T'
   end
 
-  escapable_terminators =  ['!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`']
-
-  it "supports escaping characters when used as a terminator" do
-    escapable_terminators.each do |c|
-      ref = "(?-mix:#{c})"
-      pattern = eval("%r" + c + "\\" + c + c)
-      pattern.to_s.should == ref
-    end
-  end
-
-  it "treats an escaped non-escapable character normally when used as a terminator" do
-    all_terminators = [*("!".."/"), *(":".."@"), *("[".."`"), *("{".."~")]
-    special_cases = ['(', '{', '[', '<', '\\', '=', '~']
-    (all_terminators - special_cases - escapable_terminators).each do |c|
-      ref = "(?-mix:\\#{c})"
-      pattern = eval("%r" + c + "\\" + c + c)
-      pattern.to_s.should == ref
-    end
-  end
-
   it "support handling unicode 9.0 characters with POSIX bracket expressions" do
     char_lowercase = "\u{104D8}" # OSAGE SMALL LETTER A
     /[[:lower:]]/.match(char_lowercase).to_s.should == char_lowercase
diff --git a/spec/ruby/language/rescue_spec.rb b/spec/ruby/language/rescue_spec.rb
index a912e17431..cf16d8f6f8 100644
--- a/spec/ruby/language/rescue_spec.rb
+++ b/spec/ruby/language/rescue_spec.rb
@@ -23,11 +23,127 @@ describe "The rescue keyword" do
     end.should == :caught
   end
 
-  it "can capture the raised exception in a local variable" do
-    begin
-      raise SpecificExampleException, "some text"
-    rescue SpecificExampleException => e
-      e.message.should == "some text"
+  describe 'can capture the raised exception' do
+    before :all do
+      require_relative 'fixtures/rescue_captures'
+    end
+
+    it 'in a local variable' do
+      RescueSpecs::LocalVariableCaptor.should_capture_exception
+    end
+
+    it 'in a class variable' do
+      RescueSpecs::ClassVariableCaptor.should_capture_exception
+    end
+
+    it 'in a constant' do
+      RescueSpecs::ConstantCaptor.should_capture_exception
+    end
+
+    it 'in a global variable' do
+      RescueSpecs::GlobalVariableCaptor.should_capture_exception
+    end
+
+    it 'in an instance variable' do
+      RescueSpecs::InstanceVariableCaptor.should_capture_exception
+    end
+
+    it 'using a safely navigated setter method' do
+      RescueSpecs::SafeNavigationSetterCaptor.should_capture_exception
+    end
+
+    it 'using a safely navigated setter method on a nil target' do
+      target = nil
+      begin
+        raise SpecificExampleException, "Raising this to be handled below"
+      rescue SpecificExampleException => target&.captured_error
+        :caught
+      end.should == :caught
+      target.should == nil
+    end
+
+    it 'using a setter method' do
+      RescueSpecs::SetterCaptor.should_capture_exception
+    end
+
+    it 'using a square brackets setter' do
+      RescueSpecs::SquareBracketsCaptor.should_capture_exception
+    end
+  end
+
+  describe 'capturing in a local variable (that defines it)' do
+    it 'captures successfully in a method' do
+      ScratchPad.record []
+
+      def a
+        raise "message"
+      rescue => e
+        ScratchPad << e.message
+      end
+
+      a
+      ScratchPad.recorded.should == ["message"]
+    end
+
+    it 'captures successfully in a block' do
+      ScratchPad.record []
+
+      p = proc do
+        raise "message"
+      rescue => e
+        ScratchPad << e.message
+      end
+
+      p.call
+      ScratchPad.recorded.should == ["message"]
+    end
+
+    it 'captures successfully in a class' do
+      ScratchPad.record []
+
+      class RescueSpecs::C
+        raise "message"
+      rescue => e
+        ScratchPad << e.message
+      end
+
+      ScratchPad.recorded.should == ["message"]
+    end
+
+    it 'captures successfully in a module' do
+      ScratchPad.record []
+
+      module RescueSpecs::M
+        raise "message"
+      rescue => e
+        ScratchPad << e.message
+      end
+
+      ScratchPad.recorded.should == ["message"]
+    end
+
+    it 'captures sucpcessfully in a singleton class' do
+      ScratchPad.record []
+
+      class << Object.new
+        raise "message"
+      rescue => e
+        ScratchPad << e.message
+      end
+
+      ScratchPad.recorded.should == ["message"]
+    end
+
+    it 'captures successfully at the top-level' do
+      ScratchPad.record []
+      loaded_features = $".dup
+      begin
+        require_relative 'fixtures/rescue/top_level'
+
+        ScratchPad.recorded.should == ["message"]
+      ensure
+        $".replace loaded_features
+      end
     end
   end
 
@@ -70,7 +186,7 @@ describe "The rescue keyword" do
     rescue *exception_list
       caught_it = true
     end
-    caught_it.should be_true
+    caught_it.should == true
     caught = []
     [->{raise ArbitraryException}, ->{raise SpecificExampleException}].each do |block|
       begin
@@ -81,10 +197,22 @@ describe "The rescue keyword" do
     end
     caught.size.should == 2
     exception_list.each do |exception_class|
-      caught.map{|e| e.class}.should include(exception_class)
+      caught.map{|e| e.class}.should.include?(exception_class)
     end
   end
 
+  it "converts the splatted list of exceptions using #to_a" do
+    exceptions = mock("to_a")
+    exceptions.should_receive(:to_a).and_return(exception_list)
+    caught_it = false
+    begin
+      raise SpecificExampleException, "not important"
+    rescue *exceptions
+      caught_it = true
+    end
+    caught_it.should == true
+  end
+
   it "can combine a splatted list of exceptions with a literal list of exceptions" do
     caught_it = false
     begin
@@ -92,7 +220,7 @@ describe "The rescue keyword" do
     rescue ArbitraryException, *exception_list
       caught_it = true
     end
-    caught_it.should be_true
+    caught_it.should == true
     caught = []
     [->{raise ArbitraryException}, ->{raise SpecificExampleException}].each do |block|
       begin
@@ -103,7 +231,7 @@ describe "The rescue keyword" do
     end
     caught.size.should == 2
     exception_list.each do |exception_class|
-      caught.map{|e| e.class}.should include(exception_class)
+      caught.map{|e| e.class}.should.include?(exception_class)
     end
   end
 
@@ -113,7 +241,7 @@ describe "The rescue keyword" do
         raise OtherCustomException, "not rescued!"
       rescue *exception_list
       end
-    end.should raise_error(OtherCustomException)
+    end.should.raise(OtherCustomException)
   end
 
   it "can rescue different types of exceptions in different ways" do
@@ -149,7 +277,7 @@ describe "The rescue keyword" do
       rescue ArgumentError
       end
     rescue StandardError => e
-      e.backtrace.first.should include ":in `raise_standard_error'"
+      e.backtrace.first.should =~ /:in [`'](?:RescueSpecs\.)?raise_standard_error'/
     else
       fail("exception wasn't handled by the correct rescue block")
     end
@@ -208,34 +336,16 @@ describe "The rescue keyword" do
     ScratchPad.recorded.should == [:one, :else_ran, :ensure_ran, :outside_begin]
   end
 
-  ruby_version_is ''...'2.6' do
-    it "will execute an else block even without rescue and ensure" do
-      -> {
-        eval <<-ruby
-          begin
-            ScratchPad << :begin
-          else
-            ScratchPad << :else
-          end
-        ruby
-      }.should complain(/else without rescue is useless/)
-
-      ScratchPad.recorded.should == [:begin, :else]
-    end
-  end
-
-  ruby_version_is '2.6' do
-    it "raises SyntaxError when else is used without rescue and ensure" do
-      -> {
-        eval <<-ruby
-          begin
-            ScratchPad << :begin
-          else
-            ScratchPad << :else
-          end
-        ruby
-      }.should raise_error(SyntaxError, /else without rescue is useless/)
-    end
+  it "raises SyntaxError when else is used without rescue and ensure" do
+    -> {
+      eval <<-ruby
+        begin
+          ScratchPad << :begin
+        else
+          ScratchPad << :else
+        end
+      ruby
+    }.should.raise(SyntaxError, /else without rescue is useless/)
   end
 
   it "will not execute an else block if an exception was raised" do
@@ -303,7 +413,7 @@ describe "The rescue keyword" do
         ScratchPad << :two
         raise SpecificExampleException, "an error from else"
       end
-    end.should raise_error(SpecificExampleException)
+    end.should.raise(SpecificExampleException)
     ScratchPad.recorded.should == [:one, :two]
   end
 
@@ -335,7 +445,7 @@ describe "The rescue keyword" do
           rescue
             ScratchPad << :caught
           end
-        }.should raise_error(exception.class)
+        }.should.raise(exception.class)
       end
       ScratchPad.recorded.should == []
     end
@@ -366,7 +476,7 @@ describe "The rescue keyword" do
         raise "error"
       rescue rescuer
       end
-    }.should raise_error(TypeError) { |e|
+    }.should.raise(TypeError) { |e|
       e.message.should =~ /class or module required for rescue clause/
     }
   end
@@ -378,7 +488,7 @@ describe "The rescue keyword" do
         raise "error"
       rescue *rescuer
       end
-    }.should raise_error(TypeError) { |e|
+    }.should.raise(TypeError) { |e|
       e.message.should =~ /class or module required for rescue clause/
     }
   end
@@ -398,9 +508,9 @@ describe "The rescue keyword" do
         raise "from block"
       rescue (raise "from rescue expression")
       end
-    }.should raise_error(RuntimeError, "from rescue expression") do |e|
+    }.should.raise(RuntimeError, "from rescue expression") { |e|
       e.cause.message.should == "from block"
-    end
+    }
   end
 
   it "should splat the handling Error classes" do
@@ -432,21 +542,19 @@ describe "The rescue keyword" do
           :caught
         }
       ruby
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 
-  ruby_version_is "2.5" do
-    it "allows rescue in 'do end' block" do
-      lambda = eval <<-ruby
-        lambda do
-          raise SpecificExampleException
-        rescue SpecificExampleException
-          ScratchPad << :caught
-        end.call
-      ruby
+  it "allows rescue in 'do end' block" do
+    lambda = eval <<-ruby
+      lambda do
+        raise SpecificExampleException
+      rescue SpecificExampleException
+        ScratchPad << :caught
+      end.call
+    ruby
 
-      ScratchPad.recorded.should == [:caught]
-    end
+    ScratchPad.recorded.should == [:caught]
   end
 
   it "allows 'rescue' in method arguments" do
@@ -455,10 +563,25 @@ describe "The rescue keyword" do
   end
 
   it "requires the 'rescue' in method arguments to be wrapped in parens" do
-    -> { eval '1.+(1 rescue 1)' }.should raise_error(SyntaxError)
+    -> { eval '1.+(1 rescue 1)' }.should.raise(SyntaxError)
     eval('1.+((1 rescue 1))').should == 2
   end
 
+  ruby_version_is "3.4" do
+    it "does not introduce extra backtrace entries" do
+      def foo
+        begin
+          raise "oops"
+        rescue
+          return caller(0, 2)
+        end
+      end
+      line = __LINE__
+      foo[0].should =~ /#{__FILE__}:#{line-3}:in 'foo'/
+      foo[1].should =~ /#{__FILE__}:#{line+2}:in 'block/
+    end
+  end
+
   describe "inline form" do
     it "can be inlined" do
       a = 1/0 rescue 1
@@ -470,7 +593,7 @@ describe "The rescue keyword" do
         eval <<-ruby
           a = 1 rescue RuntimeError 2
         ruby
-      }.should raise_error(SyntaxError)
+      }.should.raise(SyntaxError)
     end
 
     it "rescues only StandardError and its subclasses" do
@@ -479,7 +602,15 @@ describe "The rescue keyword" do
 
       -> {
         a = raise(Exception) rescue 1
-      }.should raise_error(Exception)
+      }.should.raise(Exception)
+    end
+
+    it "rescues with multiple assignment" do
+
+      a, b = raise rescue [1, 2]
+
+      a.should == 1
+      b.should == 2
     end
   end
 end
diff --git a/spec/ruby/language/reserved_keywords.rb b/spec/ruby/language/reserved_keywords.rb
new file mode 100644
index 0000000000..bd1a55feec
--- /dev/null
+++ b/spec/ruby/language/reserved_keywords.rb
@@ -0,0 +1,149 @@
+require_relative '../spec_helper'
+
+describe "Ruby's reserved keywords" do
+  # Copied from https://github.com/ruby/ruby/blob/master/defs/keywords
+  keywords = %w[
+    alias
+    and
+    begin
+    BEGIN
+    break
+    case
+    class
+    def
+    defined?
+    do
+    else
+    elsif
+    end
+    END
+    ensure
+    false
+    for
+    if
+    in
+    module
+    next
+    nil
+    not
+    or
+    redo
+    rescue
+    retry
+    return
+    self
+    super
+    then
+    true
+    undef
+    unless
+    until
+    when
+    while
+    yield
+    __ENCODING__
+    __FILE__
+    __LINE__
+  ]
+
+  keywords.each do |name|
+    describe "keyword '#{name}'" do
+      it "can't be used as local variable name" do
+        -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+            #{name} = :local_variable
+        RUBY
+      end
+
+      if name == "defined?"
+        it "can't be used as an instance variable name" do
+          -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+            @#{name} = :instance_variable
+          RUBY
+        end
+
+        it "can't be used as a class variable name" do
+          -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+            class C
+              @@#{name} = :class_variable
+            end
+          RUBY
+        end
+
+        it "can't be used as a global variable name" do
+          -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+            $#{name} = :global_variable
+          RUBY
+        end
+      else
+        it "can be used as an instance variable name" do
+          result = eval <<~RUBY
+            @#{name} = :instance_variable
+            @#{name}
+          RUBY
+
+          result.should == :instance_variable
+        end
+
+        it "can be used as a class variable name" do
+          result = eval <<~RUBY
+            class C
+              @@#{name} = :class_variable
+              @@#{name}
+            end
+          RUBY
+
+          result.should == :class_variable
+        end
+
+        it "can be used as a global variable name" do
+          result = eval <<~RUBY
+            $#{name} = :global_variable
+            $#{name}
+          RUBY
+
+          result.should == :global_variable
+        end
+      end
+
+      it "can't be used as a positional parameter name" do
+        -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+          def x(#{name}); end
+        RUBY
+      end
+
+      invalid_kw_param_names = ["BEGIN","END","defined?"]
+
+      if invalid_kw_param_names.include?(name)
+        it "can't be used a keyword parameter name" do
+          -> { eval(<<~RUBY) }.should.raise(SyntaxError)
+            def m(#{name}:); end
+          RUBY
+        end
+      else
+        it "can be used a keyword parameter name" do
+          result = instance_eval <<~RUBY
+            def m(#{name}:)
+              binding.local_variable_get(:#{name})
+            end
+
+            m(#{name}: :argument)
+          RUBY
+
+          result.should == :argument
+        end
+      end
+
+      it "can be used as a method name" do
+        result = instance_eval <<~RUBY
+          def #{name}
+            :method_return_value
+          end
+
+          send(:#{name})
+        RUBY
+
+        result.should == :method_return_value
+      end
+    end
+  end
+end
diff --git a/spec/ruby/language/retry_spec.rb b/spec/ruby/language/retry_spec.rb
index ee5377946f..39e58b7b5d 100644
--- a/spec/ruby/language/retry_spec.rb
+++ b/spec/ruby/language/retry_spec.rb
@@ -31,8 +31,11 @@ describe "The retry statement" do
     results.should == [1, 2, 3, 1, 2, 4, 5, 6, 4, 5]
   end
 
-  it "raises a SyntaxError when used outside of a begin statement" do
-    -> { eval 'retry' }.should raise_error(SyntaxError)
+  it "raises a SyntaxError when used outside of a rescue statement" do
+    -> { eval 'retry' }.should.raise(SyntaxError)
+    -> { eval 'begin; retry; end' }.should.raise(SyntaxError)
+    -> { eval 'def m; retry; end' }.should.raise(SyntaxError)
+    -> { eval 'module RetrySpecs; retry; end' }.should.raise(SyntaxError)
   end
 end
 
diff --git a/spec/ruby/language/return_spec.rb b/spec/ruby/language/return_spec.rb
index 7eef6d06ca..36a3cba4d7 100644
--- a/spec/ruby/language/return_spec.rb
+++ b/spec/ruby/language/return_spec.rb
@@ -19,7 +19,7 @@ describe "The return keyword" do
 
   it "returns nil by default" do
     def r; return; end
-    r().should be_nil
+    r().should == nil
   end
 
   describe "in a Thread" do
@@ -31,7 +31,7 @@ describe "The return keyword" do
           e
         end
       }
-      t.value.should be_an_instance_of(LocalJumpError)
+      t.value.should.instance_of?(LocalJumpError)
     end
   end
 
@@ -176,11 +176,11 @@ describe "The return keyword" do
     end
 
     it "causes lambda to return nil if invoked without any arguments" do
-      -> { return; 456 }.call.should be_nil
+      -> { return; 456 }.call.should == nil
     end
 
     it "causes lambda to return nil if invoked with an empty expression" do
-      -> { return (); 456 }.call.should be_nil
+      -> { return (); 456 }.call.should == nil
     end
 
     it "causes lambda to return the value passed to return" do
@@ -229,7 +229,7 @@ describe "The return keyword" do
       def f
         1.times { 1.times {return true}; false}; false
       end
-      f.should be_true
+      f.should == true
     end
   end
 
@@ -250,261 +250,240 @@ describe "The return keyword" do
     end
   end
 
-  ruby_version_is '2.4.2' do
-    describe "at top level" do
-      before :each do
-        @filename = tmp("top_return.rb")
-        ScratchPad.record []
-      end
+  describe "at top level" do
+    before :each do
+      @filename = tmp("top_return.rb")
+      ScratchPad.record []
+    end
 
-      after do
-        rm_r @filename
-      end
+    after do
+      rm_r @filename
+    end
 
-      it "stops file execution" do
-        ruby_exe(<<-END_OF_CODE).should == "before return\n"
-          puts "before return"
-          return
+    it "stops file execution" do
+      ruby_exe(<<-END_OF_CODE).should == "before return\n"
+        puts "before return"
+        return
 
-          puts "after return"
+        puts "after return"
+      END_OF_CODE
+
+      $?.exitstatus.should == 0
+    end
+
+    describe "within if" do
+      it "is allowed" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before if"
+          if true
+            return
+          end
+
+          ScratchPad << "after if"
         END_OF_CODE
 
-        $?.exitstatus.should == 0
+        load @filename
+        ScratchPad.recorded.should == ["before if"]
       end
+    end
 
-      describe "within if" do
-        it "is allowed" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before if"
-            if true
-              return
-            end
+    describe "within while loop" do
+      it "is allowed" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before while"
+          while true
+            return
+          end
 
-            ScratchPad << "after if"
-          END_OF_CODE
+          ScratchPad << "after while"
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before if"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before while"]
       end
+    end
 
-      describe "within while loop" do
-        it "is allowed" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before while"
-            while true
-              return
-            end
+    describe "within a begin" do
+      it "is allowed in begin block" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before begin"
+          begin
+            return
+          end
 
-            ScratchPad << "after while"
-          END_OF_CODE
+          ScratchPad << "after begin"
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before while"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before begin"]
       end
 
-      describe "within a begin" do
-        it "is allowed in begin block" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before begin"
-            begin
-              return
-            end
+      it "is allowed in ensure block" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before begin"
+          begin
+          ensure
+            return
+          end
 
-            ScratchPad << "after begin"
-          END_OF_CODE
+          ScratchPad << "after begin"
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before begin"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before begin"]
+      end
 
-        it "is allowed in ensure block" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before begin"
-            begin
-            ensure
-              return
-            end
+      it "is allowed in rescue block" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before begin"
+          begin
+            raise
+          rescue RuntimeError
+            return
+          end
 
-            ScratchPad << "after begin"
-          END_OF_CODE
+          ScratchPad << "after begin"
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before begin"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before begin"]
+      end
 
-        it "is allowed in rescue block" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before begin"
-            begin
-              raise
-            rescue RuntimeError
-              return
-            end
+      it "fires ensure block before returning" do
+        ruby_exe(<<-END_OF_CODE).should == "within ensure\n"
+          begin
+            return
+          ensure
+            puts "within ensure"
+          end
 
-            ScratchPad << "after begin"
-          END_OF_CODE
+          puts "after begin"
+        END_OF_CODE
+      end
 
-          load @filename
-          ScratchPad.recorded.should == ["before begin"]
-        end
+      it "fires ensure block before returning while loads file" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before begin"
+          begin
+            return
+          ensure
+            ScratchPad << "within ensure"
+          end
 
-        it "fires ensure block before returning" do
-          ruby_exe(<<-END_OF_CODE).should == "within ensure\n"
-            begin
-              return
-            ensure
-              puts "within ensure"
-            end
+          ScratchPad << "after begin"
+        END_OF_CODE
 
-            puts "after begin"
-          END_OF_CODE
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before begin", "within ensure"]
+      end
 
-        ruby_bug "#14061", "2.4"..."2.5" do
-          it "fires ensure block before returning while loads file" do
-            File.write(@filename, <<-END_OF_CODE)
-              ScratchPad << "before begin"
-              begin
-                return
-              ensure
-                ScratchPad << "within ensure"
-              end
-
-              ScratchPad << "after begin"
-            END_OF_CODE
-
-            load @filename
-            ScratchPad.recorded.should == ["before begin", "within ensure"]
+      it "swallows exception if returns in ensure block" do
+        File.write(@filename, <<-END_OF_CODE)
+          begin
+            raise
+          ensure
+            ScratchPad << "before return"
+            return
           end
-        end
+        END_OF_CODE
 
-        it "swallows exception if returns in ensure block" do
-          File.write(@filename, <<-END_OF_CODE)
-            begin
-              raise
-            ensure
-              ScratchPad << "before return"
-              return
-            end
-          END_OF_CODE
-
-          load @filename
-          ScratchPad.recorded.should == ["before return"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before return"]
       end
+    end
 
-      describe "within a block" do
-        it "is allowed" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before call"
-            proc { return }.call
+    describe "within a block" do
+      it "is allowed" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before call"
+          proc { return }.call
 
-            ScratchPad << "after call"
-          END_OF_CODE
+          ScratchPad << "after call"
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before call"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before call"]
       end
+    end
 
-      describe "within a class" do
-        ruby_version_is ""..."2.5" do
-          it "is allowed" do
-            File.write(@filename, <<-END_OF_CODE)
-              class ReturnSpecs::A
-                ScratchPad << "before return"
-                return
-
-                ScratchPad << "after return"
-              end
-            END_OF_CODE
+    describe "within a class" do
+      it "raises a SyntaxError" do
+        File.write(@filename, <<-END_OF_CODE)
+          class ReturnSpecs::A
+            ScratchPad << "before return"
+            return
 
-            load @filename
-            ScratchPad.recorded.should == ["before return"]
+            ScratchPad << "after return"
           end
-        end
-
-        ruby_version_is "2.5" do
-          it "raises a SyntaxError" do
-            File.write(@filename, <<-END_OF_CODE)
-              class ReturnSpecs::A
-                ScratchPad << "before return"
-                return
-
-                ScratchPad << "after return"
-              end
-            END_OF_CODE
+        END_OF_CODE
 
-            -> { load @filename }.should raise_error(SyntaxError)
-          end
-        end
+        -> { load @filename }.should.raise(SyntaxError)
       end
+    end
 
-      describe "within a block within a class" do
-        ruby_version_is "2.7" do
-          it "is not allowed" do
-            File.write(@filename, <<-END_OF_CODE)
-              class ReturnSpecs::A
-                ScratchPad << "before return"
-                1.times { return }
-                ScratchPad << "after return"
-              end
-            END_OF_CODE
-
-            -> { load @filename }.should raise_error(LocalJumpError)
+    describe "within a block within a class" do
+      it "is not allowed" do
+        File.write(@filename, <<-END_OF_CODE)
+          class ReturnSpecs::A
+            ScratchPad << "before return"
+            1.times { return }
+            ScratchPad << "after return"
           end
-        end
+        END_OF_CODE
+
+        -> { load @filename }.should.raise(LocalJumpError)
       end
+    end
 
-      describe "file loading" do
-        it "stops file loading and execution" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before return"
+    describe "within BEGIN" do
+      it "is allowed" do
+        File.write(@filename, <<-END_OF_CODE)
+          BEGIN {
+            ScratchPad << "before call"
             return
-            ScratchPad << "after return"
-          END_OF_CODE
+            ScratchPad << "after call"
+          }
+        END_OF_CODE
 
-          load @filename
-          ScratchPad.recorded.should == ["before return"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before call"]
       end
+    end
 
-      describe "file requiring" do
-        it "stops file loading and execution" do
-          File.write(@filename, <<-END_OF_CODE)
-            ScratchPad << "before return"
-            return
-            ScratchPad << "after return"
-          END_OF_CODE
+    describe "file loading" do
+      it "stops file loading and execution" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before return"
+          return
+          ScratchPad << "after return"
+        END_OF_CODE
 
-          require @filename
-          ScratchPad.recorded.should == ["before return"]
-        end
+        load @filename
+        ScratchPad.recorded.should == ["before return"]
       end
+    end
 
-      describe "return with argument" do
-        ruby_version_is ""..."2.7" do
-          it "does not affect exit status" do
-            ruby_exe(<<-END_OF_CODE).should == ""
-              return 10
-            END_OF_CODE
+    describe "file requiring" do
+      it "stops file loading and execution" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before return"
+          return
+          ScratchPad << "after return"
+        END_OF_CODE
 
-            $?.exitstatus.should == 0
-          end
-        end
+        require @filename
+        ScratchPad.recorded.should == ["before return"]
+      end
+    end
 
-        ruby_version_is "2.7" do
-          it "warns but does not affect exit status" do
-            err = ruby_exe(<<-END_OF_CODE, args: "2>&1")
-              return 10
-            END_OF_CODE
-            $?.exitstatus.should == 0
+    describe "return with argument" do
+      it "warns but does not affect exit status" do
+        err = ruby_exe(<<-END_OF_CODE, args: "2>&1")
+          return 10
+        END_OF_CODE
+        $?.exitstatus.should == 0
 
-            err.should =~ /warning: argument of top-level return is ignored/
-          end
-        end
+        err.should =~ /warning: argument of top-level return is ignored/
       end
     end
   end
diff --git a/spec/ruby/language/safe_navigator_spec.rb b/spec/ruby/language/safe_navigator_spec.rb
index c3aecff2dd..e8b429631d 100644
--- a/spec/ruby/language/safe_navigator_spec.rb
+++ b/spec/ruby/language/safe_navigator_spec.rb
@@ -2,48 +2,48 @@ require_relative '../spec_helper'
 
 describe "Safe navigator" do
   it "requires a method name to be provided" do
-    -> { eval("obj&. {}") }.should raise_error(SyntaxError)
+    -> { eval("obj&. {}") }.should.raise(SyntaxError)
   end
 
   context "when context is nil" do
     it "always returns nil" do
-      eval("nil&.unknown").should == nil
-      eval("[][10]&.unknown").should == nil
+      nil&.unknown.should == nil
+      [][10]&.unknown.should == nil
     end
 
     it "can be chained" do
-      eval("nil&.one&.two&.three").should == nil
+      nil&.one&.two&.three.should == nil
     end
 
     it "doesn't evaluate arguments" do
       obj = Object.new
       obj.should_not_receive(:m)
-      eval("nil&.unknown(obj.m) { obj.m }")
+      nil&.unknown(obj.m) { obj.m }
     end
   end
 
   context "when context is false" do
     it "calls the method" do
-      eval("false&.to_s").should == "false"
+      false&.to_s.should == "false"
 
-      -> { eval("false&.unknown") }.should raise_error(NoMethodError)
+      -> { false&.unknown }.should.raise(NoMethodError)
     end
   end
 
   context "when context is truthy" do
     it "calls the method" do
-      eval("1&.to_s").should == "1"
+      1&.to_s.should == "1"
 
-      -> { eval("1&.unknown") }.should raise_error(NoMethodError)
+      -> { 1&.unknown }.should.raise(NoMethodError)
     end
   end
 
   it "takes a list of arguments" do
-    eval("[1,2,3]&.first(2)").should == [1,2]
+    [1,2,3]&.first(2).should == [1,2]
   end
 
   it "takes a block" do
-    eval("[1,2]&.map { |i| i * 2 }").should == [2, 4]
+    [1,2]&.map { |i| i * 2 }.should == [2, 4]
   end
 
   it "allows assignment methods" do
@@ -56,29 +56,77 @@ describe "Safe navigator" do
     end
     obj = klass.new
 
-    eval("obj&.foo = 3").should == 3
+    (obj&.foo = 3).should == 3
     obj.foo.should == 3
 
     obj = nil
-    eval("obj&.foo = 3").should == nil
+    (obj&.foo = 3).should == nil
   end
 
   it "allows assignment operators" do
     klass = Class.new do
-      attr_accessor :m
+      attr_reader :m
 
       def initialize
         @m = 0
       end
+
+      def m=(v)
+        @m = v
+        42
+      end
     end
 
     obj = klass.new
 
-    eval("obj&.m += 3")
+    obj&.m += 3
     obj.m.should == 3
 
     obj = nil
-    eval("obj&.m += 3").should == nil
+    (obj&.m += 3).should == nil
+  end
+
+  it "allows ||= operator" do
+    klass = Class.new do
+      attr_reader :m
+
+      def initialize
+        @m = false
+      end
+
+      def m=(v)
+        @m = v
+        42
+      end
+    end
+
+    obj = klass.new
+
+    (obj&.m ||= true).should == true
+    obj.m.should == true
+
+    obj = nil
+    (obj&.m ||= true).should == nil
+    obj.should == nil
+  end
+
+  it "allows &&= operator" do
+    klass = Class.new do
+      attr_accessor :m
+
+      def initialize
+        @m = true
+      end
+    end
+
+    obj = klass.new
+
+    (obj&.m &&= false).should == false
+    obj.m.should == false
+
+    obj = nil
+    (obj&.m &&= false).should == nil
+    obj.should == nil
   end
 
   it "does not call the operator method lazily with an assignment operator" do
@@ -91,8 +139,8 @@ describe "Safe navigator" do
     obj = klass.new
 
     -> {
-      eval("obj&.foo += 3")
-    }.should raise_error(NoMethodError) { |e|
+      obj&.foo += 3
+    }.should.raise(NoMethodError) { |e|
       e.name.should == :+
     }
   end
diff --git a/spec/ruby/language/safe_spec.rb b/spec/ruby/language/safe_spec.rb
index be150df9d1..03ae96148e 100644
--- a/spec/ruby/language/safe_spec.rb
+++ b/spec/ruby/language/safe_spec.rb
@@ -1,137 +1,11 @@
 require_relative '../spec_helper'
 
 describe "The $SAFE variable" do
-
-  ruby_version_is "2.6" do
-    after :each do
-      $SAFE = 0
-    end
-  end
-
-  it "is 0 by default" do
-    $SAFE.should == 0
-    proc {
-      $SAFE.should == 0
-    }.call
-  end
-
-  it "can be set to 0" do
-    proc {
-      $SAFE = 0
-      $SAFE.should == 0
-    }.call
-  end
-
-  it "can be set to 1" do
-    proc {
-      $SAFE = 1
-      $SAFE.should == 1
-    }.call
-  end
-
-  [2, 3, 4].each do |n|
-    it "cannot be set to #{n}" do
-      -> {
-        proc {
-          $SAFE = n
-        }.call
-      }.should raise_error(ArgumentError, /\$SAFE=2 to 4 are obsolete/)
-    end
-  end
-
-  ruby_version_is ""..."2.6" do
-    it "cannot be set to values below 0" do
-      -> {
-        proc {
-          $SAFE = -100
-        }.call
-      }.should raise_error(SecurityError, /tried to downgrade safe level from 0 to -100/)
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "raises ArgumentError when set to values below 0" do
-      -> {
-        proc {
-          $SAFE = -100
-        }.call
-      }.should raise_error(ArgumentError, "$SAFE should be >= 0")
-    end
-  end
-
-  it "cannot be set to values above 4" do
-    -> {
-      proc {
-        $SAFE = 100
-      }.call
-    }.should raise_error(ArgumentError, /\$SAFE=2 to 4 are obsolete/)
-  end
-
-  ruby_version_is ""..."2.6" do
-    it "cannot be manually lowered" do
-      proc {
-        $SAFE = 1
-        -> {
-          $SAFE = 0
-        }.should raise_error(SecurityError, /tried to downgrade safe level from 1 to 0/)
-      }.call
-    end
-
-    it "is automatically lowered when leaving a proc" do
-      $SAFE.should == 0
-      proc {
-        $SAFE = 1
-      }.call
-      $SAFE.should == 0
-    end
-
-    it "is automatically lowered when leaving a lambda" do
-      $SAFE.should == 0
-      -> {
-        $SAFE = 1
-      }.call
-      $SAFE.should == 0
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "can be manually lowered" do
-      $SAFE = 1
-      $SAFE = 0
-      $SAFE.should == 0
-    end
-
-    it "is not Proc local" do
-      $SAFE.should == 0
-      proc {
-        $SAFE = 1
-      }.call
-      $SAFE.should == 1
-    end
-
-    it "is not lambda local" do
-      $SAFE.should == 0
-      -> {
-        $SAFE = 1
-      }.call
-      $SAFE.should == 1
-    end
-
-    it "is global like regular global variables" do
-      Thread.new { $SAFE }.value.should == 0
-      $SAFE = 1
-      Thread.new { $SAFE }.value.should == 1
-    end
-  end
-
-  it "can be read when default from Thread#safe_level" do
-    Thread.current.safe_level.should == 0
-  end
-
-  it "can be read when modified from Thread#safe_level" do
-    proc {
-      $SAFE = 1
-      Thread.current.safe_level.should == 1
-    }.call
+  it "$SAFE is a regular global variable" do
+    $SAFE.should == nil
+    $SAFE = 42
+    $SAFE.should == 42
+  ensure
+    $SAFE = nil
   end
 end
diff --git a/spec/ruby/language/send_spec.rb b/spec/ruby/language/send_spec.rb
index c56d5e8c26..f56a77d529 100644
--- a/spec/ruby/language/send_spec.rb
+++ b/spec/ruby/language/send_spec.rb
@@ -22,7 +22,7 @@ describe "Invoking a method" do
     it "raises ArgumentError if the method has a positive arity" do
       -> {
         specs.fooM1
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -38,12 +38,12 @@ describe "Invoking a method" do
     it "raises ArgumentError if the methods arity doesn't match" do
       -> {
         specs.fooM1(1,2)
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
   describe "with optional arguments" do
-    it "uses the optional argument if none is is passed" do
+    it "uses the optional argument if none is passed" do
       specs.fooM0O1.should == [1]
     end
 
@@ -54,7 +54,7 @@ describe "Invoking a method" do
     it "raises ArgumentError if extra arguments are passed" do
       -> {
         specs.fooM0O1(2,3)
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -66,13 +66,13 @@ describe "Invoking a method" do
     it "raises an ArgumentError if there are no values for the mandatory args" do
       -> {
         specs.fooM1O1
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError if too many values are passed" do
       -> {
         specs.fooM1O1(1,2,3)
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -94,7 +94,7 @@ describe "Invoking a method" do
 
   it "with a block converts the block to a Proc" do
     prc = specs.makeproc { "hello" }
-    prc.should be_kind_of(Proc)
+    prc.should.is_a?(Proc)
     prc.call.should == "hello"
   end
 
@@ -106,10 +106,28 @@ describe "Invoking a method" do
     specs.yield_now(&o).should == :from_to_proc
   end
 
+  ruby_version_is "4.0" do
+    it "raises TypeError if 'to_proc' doesn't return a Proc" do
+      o = LangSendSpecs::RawToProc.new(42)
+
+      -> {
+        specs.makeproc(&o)
+      }.should raise_consistent_error(TypeError, "can't convert LangSendSpecs::RawToProc into Proc (LangSendSpecs::RawToProc#to_proc gives Integer)")
+    end
+
+    it "raises TypeError if block object isn't a Proc and doesn't respond to `to_proc`" do
+      o = Object.new
+
+      -> {
+        specs.makeproc(&o)
+      }.should.raise(TypeError, "no implicit conversion of Object into Proc")
+    end
+  end
+
   it "raises a SyntaxError with both a literal block and an object as block" do
     -> {
       eval "specs.oneb(10, &l){ 42 }"
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 
   it "with same names as existing variables is ok" do
@@ -194,21 +212,42 @@ describe "Invoking a method" do
       o.args.should == [1,2]
     end
 
-    it "raises NameError if invoked as a vcall" do
-      -> { no_such_method }.should raise_error NameError
+    describe "if invoked as a vcall" do
+      it "raises NameError" do
+        -> { no_such_method }.should.raise NameError
+      end
+
+      it "raises NameError with $! as a cause" do
+        begin
+          raise RuntimeError.new
+        rescue => cause
+          -> { no_such_method }.should.raise(NameError, cause:)
+        end
+      end
     end
 
     it "should omit the method_missing call from the backtrace for NameError" do
-      -> { no_such_method }.should raise_error { |e| e.backtrace.first.should_not include("method_missing") }
+      -> { no_such_method }.should.raise { |e| e.backtrace.first.should_not.include?("method_missing") }
     end
 
-    it "raises NoMethodError if invoked as an unambiguous method call" do
-      -> { no_such_method() }.should raise_error NoMethodError
-      -> { no_such_method(1,2,3) }.should raise_error NoMethodError
+    describe "if invoked as an unambiguous method call" do
+      it "raises NoMethodError" do
+        -> { no_such_method() }.should.raise NoMethodError
+        -> { no_such_method(1,2,3) }.should.raise NoMethodError
+      end
+
+      it "raises NoMethodError with $! as a cause" do
+        begin
+          raise
+        rescue => cause
+          -> { no_such_method() }.should.raise(NoMethodError, cause:)
+          -> { no_such_method(1,2,3) }.should.raise(NoMethodError, cause:)
+        end
+      end
     end
 
     it "should omit the method_missing call from the backtrace for NoMethodError" do
-      -> { no_such_method() }.should raise_error { |e| e.backtrace.first.should_not include("method_missing") }
+      -> { no_such_method() }.should.raise { |e| e.backtrace.first.should_not.include?("method_missing") }
     end
   end
 
@@ -258,20 +297,10 @@ describe "Invoking a private setter method" do
 end
 
 describe "Invoking a private getter method" do
-  ruby_version_is ""..."2.7" do
-    it "does not permit self as a receiver" do
-      receiver = LangSendSpecs::PrivateGetter.new
-      -> { receiver.call_self_foo }.should raise_error(NoMethodError)
-      -> { receiver.call_self_foo_or_equals(6) }.should raise_error(NoMethodError)
-    end
-  end
-
-  ruby_version_is "2.7" do
-    it "permits self as a receiver" do
-      receiver = LangSendSpecs::PrivateGetter.new
-      receiver.call_self_foo_or_equals(6)
-      receiver.call_self_foo.should == 6
-    end
+  it "permits self as a receiver" do
+    receiver = LangSendSpecs::PrivateGetter.new
+    receiver.call_self_foo_or_equals(6)
+    receiver.call_self_foo.should == 6
   end
 end
 
@@ -347,7 +376,7 @@ describe "Invoking a method" do
 
   it "with splat operator * and non-Array value uses value unchanged if it does not respond_to?(:to_ary)" do
     obj = Object.new
-    obj.should_not respond_to(:to_a)
+    obj.should_not.respond_to?(:to_a)
 
     specs.fooM0R(*obj).should == [obj]
     specs.fooM1R(1,*obj).should == [1, [obj]]
@@ -421,17 +450,17 @@ describe "Invoking a method" do
     specs.rest_len(0,*a,4,*5,6,7,*c,-1).should == 11
   end
 
-  it "expands the Array elements from the splat after executing the arguments and block if no other arguments follow the splat" do
+  it "expands the Array elements from the splat before applying block argument operations" do
     def self.m(*args, &block)
       [args, block]
     end
 
     args = [1, nil]
-    m(*args, &args.pop).should == [[1], nil]
+    m(*args, &args.pop).should == [[1, nil], nil]
 
     args = [1, nil]
     order = []
-    m(*(order << :args; args), &(order << :block; args.pop)).should == [[1], nil]
+    m(*(order << :args; args), &(order << :block; args.pop)).should == [[1, nil], nil]
     order.should == [:args, :block]
   end
 
diff --git a/spec/ruby/language/shared/__FILE__.rb b/spec/ruby/language/shared/__FILE__.rb
index 3e4f5c958d..7e2e871932 100644
--- a/spec/ruby/language/shared/__FILE__.rb
+++ b/spec/ruby/language/shared/__FILE__.rb
@@ -9,14 +9,14 @@ describe :language___FILE__, shared: true do
   end
 
   it "equals the absolute path of a file loaded by an absolute path" do
-    @object.send(@method, @path).should be_true
+    @object.send(@method, @path).should == true
     ScratchPad.recorded.should == [@path]
   end
 
   it "equals the absolute path of a file loaded by a relative path" do
     $LOAD_PATH << "."
     Dir.chdir CODE_LOADING_DIR do
-      @object.send(@method, "file_fixture.rb").should be_true
+      @object.send(@method, "file_fixture.rb").should == true
     end
     ScratchPad.recorded.should == [@path]
   end
diff --git a/spec/ruby/language/shared/__LINE__.rb b/spec/ruby/language/shared/__LINE__.rb
index 076b74b3ba..6bfc8c1c17 100644
--- a/spec/ruby/language/shared/__LINE__.rb
+++ b/spec/ruby/language/shared/__LINE__.rb
@@ -9,7 +9,7 @@ describe :language___LINE__, shared: true do
   end
 
   it "equals the line number of the text in a loaded file" do
-    @object.send(@method, @path).should be_true
+    @object.send(@method, @path).should == true
     ScratchPad.recorded.should == [1, 5]
   end
 end
diff --git a/spec/ruby/language/singleton_class_spec.rb b/spec/ruby/language/singleton_class_spec.rb
index df735018af..20256a323c 100644
--- a/spec/ruby/language/singleton_class_spec.rb
+++ b/spec/ruby/language/singleton_class_spec.rb
@@ -14,40 +14,40 @@ describe "A singleton class" do
     nil.singleton_class.should == NilClass
   end
 
-  it "raises a TypeError for Fixnum's" do
-    -> { 1.singleton_class }.should raise_error(TypeError)
+  it "raises a TypeError for Integer's" do
+    -> { 1.singleton_class }.should.raise(TypeError)
   end
 
   it "raises a TypeError for symbols" do
-    -> { :symbol.singleton_class }.should raise_error(TypeError)
+    -> { :symbol.singleton_class }.should.raise(TypeError)
   end
 
   it "is a singleton Class instance" do
     o = mock('x')
-    o.singleton_class.should be_kind_of(Class)
-    o.singleton_class.should_not equal(Object)
-    o.should be_kind_of(o.singleton_class)
+    o.singleton_class.should.is_a?(Class)
+    o.singleton_class.should_not.equal?(Object)
+    o.should.is_a?(o.singleton_class)
   end
 
   it "is a Class for classes" do
-    ClassSpecs::A.singleton_class.should be_kind_of(Class)
+    ClassSpecs::A.singleton_class.should.is_a?(Class)
   end
 
   it "inherits from Class for classes" do
-    Class.should be_ancestor_of(Object.singleton_class)
+    Object.singleton_class.ancestors.should.include?(Class)
   end
 
   it "is a subclass of Class's singleton class" do
     ec = ClassSpecs::A.singleton_class
-    ec.should be_kind_of(Class.singleton_class)
+    ec.should.is_a?(Class.singleton_class)
   end
 
   it "is a subclass of the same level of Class's singleton class" do
     ecec = ClassSpecs::A.singleton_class.singleton_class
     class_ec = Class.singleton_class
 
-    ecec.should be_kind_of(class_ec.singleton_class)
-    ecec.should be_kind_of(class_ec)
+    ecec.should.is_a?(class_ec.singleton_class)
+    ecec.should.is_a?(class_ec)
   end
 
   it "is a subclass of a superclass's singleton class" do
@@ -60,7 +60,7 @@ describe "A singleton class" do
       ClassSpecs::H.singleton_class.singleton_class
   end
 
-  it "for BasicObject has Class as it's superclass" do
+  it "for BasicObject has Class as its superclass" do
     BasicObject.singleton_class.superclass.should == Class
   end
 
@@ -70,11 +70,11 @@ describe "A singleton class" do
   end
 
   it "has class String as the superclass of a String instance" do
-    "blah".singleton_class.superclass.should == String
+    "blah".dup.singleton_class.superclass.should == String
   end
 
   it "doesn't have singleton class" do
-    -> { bignum_value.singleton_class.superclass.should == Bignum }.should raise_error(TypeError)
+    -> { bignum_value.singleton_class }.should.raise(TypeError)
   end
 end
 
@@ -105,20 +105,20 @@ describe "A constant on a singleton class" do
   end
 
   it "is not defined on the object's class" do
-    @object.class.const_defined?(:CONST).should be_false
+    @object.class.const_defined?(:CONST).should == false
   end
 
   it "is not defined in the singleton class opener's scope" do
     class << @object
       CONST
     end
-    -> { CONST }.should raise_error(NameError)
+    -> { CONST }.should.raise(NameError)
   end
 
   it "cannot be accessed via object::CONST" do
     -> do
       @object::CONST
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises a NameError for anonymous_module::CONST" do
@@ -129,15 +129,15 @@ describe "A constant on a singleton class" do
 
     -> do
       @object::CONST
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "appears in the singleton class constant list" do
-    @object.singleton_class.should have_constant(:CONST)
+    @object.singleton_class.should.const_defined?(:CONST, false)
   end
 
   it "does not appear in the object's class constant list" do
-    @object.class.should_not have_constant(:CONST)
+    @object.class.should_not.const_defined?(:CONST)
   end
 
   it "is not preserved when the object is duped" do
@@ -145,14 +145,14 @@ describe "A constant on a singleton class" do
 
     -> do
       class << @object; CONST; end
-    end.should raise_error(NameError)
+    end.should.raise(NameError)
   end
 
   it "is preserved when the object is cloned" do
     @object = @object.clone
 
     class << @object
-      CONST.should_not be_nil
+      CONST.should_not == nil
     end
   end
 end
@@ -168,7 +168,7 @@ describe "Defining instance methods on a singleton class" do
   end
 
   it "defines public methods" do
-    @k_sc.should have_public_instance_method(:singleton_method)
+    @k_sc.public_instance_methods(false).should.include?(:singleton_method)
   end
 end
 
@@ -181,46 +181,46 @@ describe "Instance methods of a singleton class" do
   end
 
   it "include ones of the object's class" do
-    @k_sc.should have_instance_method(:example_instance_method)
+    @k_sc.should.method_defined?(:example_instance_method, true)
   end
 
   it "does not include class methods of the object's class" do
-    @k_sc.should_not have_instance_method(:example_class_method)
+    @k_sc.should_not.method_defined?(:example_class_method)
   end
 
   it "include instance methods of Object" do
-    @a_sc.should have_instance_method(:example_instance_method_of_object)
+    @a_sc.should.method_defined?(:example_instance_method_of_object, true)
   end
 
   it "does not include class methods of Object" do
-    @a_sc.should_not have_instance_method(:example_class_method_of_object)
+    @a_sc.should_not.method_defined?(:example_class_method_of_object)
   end
 
   describe "for a class" do
     it "include instance methods of Class" do
-      @a_c_sc.should have_instance_method(:example_instance_method_of_class)
+      @a_c_sc.should.method_defined?(:example_instance_method_of_class, true)
     end
 
     it "does not include class methods of Class" do
-      @a_c_sc.should_not have_instance_method(:example_class_method_of_class)
+      @a_c_sc.should_not.method_defined?(:example_class_method_of_class)
     end
 
     it "does not include instance methods of the singleton class of Class" do
-      @a_c_sc.should_not have_instance_method(:example_instance_method_of_singleton_class)
+      @a_c_sc.should_not.method_defined?(:example_instance_method_of_singleton_class)
     end
 
     it "does not include class methods of the singleton class of Class" do
-      @a_c_sc.should_not have_instance_method(:example_class_method_of_singleton_class)
+      @a_c_sc.should_not.method_defined?(:example_class_method_of_singleton_class)
     end
   end
 
   describe "for a singleton class" do
     it "includes instance methods of the singleton class of Class" do
-      @a_c_sc.singleton_class.should have_instance_method(:example_instance_method_of_singleton_class)
+      @a_c_sc.singleton_class.should.method_defined?(:example_instance_method_of_singleton_class, true)
     end
 
     it "does not include class methods of the singleton class of Class" do
-      @a_c_sc.singleton_class.should_not have_instance_method(:example_class_method_of_singleton_class)
+      @a_c_sc.singleton_class.should_not.method_defined?(:example_class_method_of_singleton_class)
     end
   end
 end
@@ -234,46 +234,46 @@ describe "Class methods of a singleton class" do
   end
 
   it "include ones of the object's class" do
-    @k_sc.should have_method(:example_class_method)
+    @k_sc.should.respond_to?(:example_class_method)
   end
 
   it "does not include instance methods of the object's class" do
-    @k_sc.should_not have_method(:example_instance_method)
+    @k_sc.should_not.respond_to?(:example_instance_method)
   end
 
   it "include instance methods of Class" do
-    @a_sc.should have_method(:example_instance_method_of_class)
+    @a_sc.should.respond_to?(:example_instance_method_of_class)
   end
 
   it "does not include class methods of Class" do
-    @a_sc.should_not have_method(:example_class_method_of_class)
+    @a_sc.should_not.respond_to?(:example_class_method_of_class)
   end
 
   describe "for a class" do
     it "include instance methods of Class" do
-      @a_c_sc.should have_method(:example_instance_method_of_class)
+      @a_c_sc.should.respond_to?(:example_instance_method_of_class)
     end
 
     it "include class methods of Class" do
-      @a_c_sc.should have_method(:example_class_method_of_class)
+      @a_c_sc.should.respond_to?(:example_class_method_of_class)
     end
 
     it "include instance methods of the singleton class of Class" do
-      @a_c_sc.should have_method(:example_instance_method_of_singleton_class)
+      @a_c_sc.should.respond_to?(:example_instance_method_of_singleton_class)
     end
 
     it "does not include class methods of the singleton class of Class" do
-      @a_c_sc.should_not have_method(:example_class_method_of_singleton_class)
+      @a_c_sc.should_not.respond_to?(:example_class_method_of_singleton_class)
     end
   end
 
   describe "for a singleton class" do
     it "include instance methods of the singleton class of Class" do
-      @a_c_sc.singleton_class.should have_method(:example_instance_method_of_singleton_class)
+      @a_c_sc.singleton_class.should.respond_to?(:example_instance_method_of_singleton_class)
     end
 
     it "include class methods of the singleton class of Class" do
-      @a_c_sc.singleton_class.should have_method(:example_class_method_of_singleton_class)
+      @a_c_sc.singleton_class.should.respond_to?(:example_class_method_of_singleton_class)
     end
   end
 end
@@ -282,12 +282,36 @@ describe "Instantiating a singleton class" do
   it "raises a TypeError when new is called" do
     -> {
       Object.new.singleton_class.new
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises a TypeError when allocate is called" do
     -> {
       Object.new.singleton_class.allocate
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
+  end
+end
+
+describe "Frozen properties" do
+  it "is frozen if the object it is created from is frozen" do
+    o = Object.new
+    o.freeze
+    klass = o.singleton_class
+    klass.frozen?.should == true
+  end
+
+  it "will be frozen if the object it is created from becomes frozen" do
+    o = Object.new
+    klass = o.singleton_class
+    klass.frozen?.should == false
+    o.freeze
+    klass.frozen?.should == true
+  end
+
+  it "will be unfrozen if the frozen object is cloned with freeze set to false" do
+    o = Object.new
+    o.freeze
+    o2 = o.clone(freeze: false)
+    o2.singleton_class.frozen?.should == false
   end
 end
diff --git a/spec/ruby/language/source_encoding_spec.rb b/spec/ruby/language/source_encoding_spec.rb
index a0a29f63de..5a243fa2c3 100644
--- a/spec/ruby/language/source_encoding_spec.rb
+++ b/spec/ruby/language/source_encoding_spec.rb
@@ -15,7 +15,7 @@ describe "Source files" do
   end
 
   describe "encoded in UTF-16 LE without a BOM" do
-    it "are parsed because empty as they contain a NUL byte before the encoding comment" do
+    it "are parsed as empty because they contain a NUL byte before the encoding comment" do
       ruby_exe(fixture(__FILE__, "utf16-le-nobom.rb"), args: "2>&1").should == ""
     end
   end
@@ -29,7 +29,7 @@ describe "Source files" do
 
       touch(path, "wb") { |f| f.write source }
       begin
-        ruby_exe(path, args: "2>&1").should =~ /invalid multibyte char/
+        ruby_exe(path, args: "2>&1", exit_status: 1).b.should =~ /invalid multibyte char/
       ensure
         rm_r path
       end
@@ -51,7 +51,7 @@ describe "Source files" do
 
       touch(path, "wb") { |f| f.write source }
       begin
-        ruby_exe(path, args: "2>&1").should =~ /invalid multibyte char/
+        ruby_exe(path, args: "2>&1", exit_status: 1).b.should =~ /invalid multibyte char/
       ensure
         rm_r path
       end
diff --git a/spec/ruby/language/string_spec.rb b/spec/ruby/language/string_spec.rb
index a7ca00ef03..163063032f 100644
--- a/spec/ruby/language/string_spec.rb
+++ b/spec/ruby/language/string_spec.rb
@@ -1,6 +1,7 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require_relative '../spec_helper'
+require_relative 'fixtures/class_with_class_variable'
 
 # TODO: rewrite these horrid specs. it "are..." seriously?!
 
@@ -27,11 +28,21 @@ describe "Ruby character strings" do
     "#$ip".should == 'xxx'
   end
 
+  it "interpolate class variables just with the # character" do
+    object = StringSpecs::ClassWithClassVariable.new
+    object.foo.should == 'xxx'
+  end
+
   it "allows underscore as part of a variable name in a simple interpolation" do
     @my_ip = 'xxx'
     "#@my_ip".should == 'xxx'
   end
 
+  it "does not interpolate invalid variable names" do
+    "#@".should == '#@'
+    "#$%".should == '#$%'
+  end
+
   it "has characters [.(=?!# end simple # interpolation" do
     "#@ip[".should == 'xxx['
     "#@ip.".should == 'xxx.'
@@ -51,26 +62,6 @@ describe "Ruby character strings" do
     "#\$".should == '#$'
   end
 
-  it "taints the result of interpolation when an interpolated value is tainted" do
-    "#{"".taint}".tainted?.should be_true
-
-    @ip.taint
-    "#@ip".tainted?.should be_true
-
-    $ip.taint
-    "#$ip".tainted?.should be_true
-  end
-
-  it "untrusts the result of interpolation when an interpolated value is untrusted" do
-    "#{"".untrust}".untrusted?.should be_true
-
-    @ip.untrust
-    "#@ip".untrusted?.should be_true
-
-    $ip.untrust
-    "#$ip".untrusted?.should be_true
-  end
-
   it "allows using non-alnum characters as string delimiters" do
     %(hey #{@ip}).should == "hey xxx"
     %[hey #{@ip}].should == "hey xxx"
@@ -142,6 +133,12 @@ describe "Ruby character strings" do
     "#{obj}".should == '42'
   end
 
+  it "raise NoMethodError when #to_s is not defined for the object" do
+    obj = BasicObject.new
+
+    -> { "#{obj}" }.should.raise(NoMethodError)
+  end
+
   it "uses an internal representation when #to_s doesn't return a String" do
     obj = mock('to_s')
     obj.stub!(:to_s).and_return(42)
@@ -152,7 +149,7 @@ describe "Ruby character strings" do
     # is that if you interpolate an object that fails to return
     # a String, you will still get a String and not raise an
     # exception.
-    "#{obj}".should be_an_instance_of(String)
+    "#{obj}".should.instance_of?(String)
   end
 
   it "allows a dynamic string to parse a nested do...end block as an argument to a call without parens, interpolated" do
@@ -246,8 +243,16 @@ describe "Ruby String literals" do
       ruby_exe(fixture(__FILE__, "freeze_magic_comment_across_files.rb")).chomp.should == "true"
     end
 
-    it "produce different objects for literals with the same content in different files if the other file doesn't have the comment" do
-      ruby_exe(fixture(__FILE__, "freeze_magic_comment_across_files_no_comment.rb")).chomp.should == "true"
+    guard -> { !(eval("'test'").frozen? && "test".equal?("test")) } do
+      it "produces different objects for literals with the same content in different files if the other file doesn't have the comment and String literals aren't frozen by default" do
+        ruby_exe(fixture(__FILE__, "freeze_magic_comment_across_files_no_comment.rb")).chomp.should == "true"
+      end
+    end
+
+    guard -> { eval("'test'").frozen? && "test".equal?("test") } do
+      it "produces the same objects for literals with the same content in different files if the other file doesn't have the comment and String literals are frozen by default" do
+        ruby_exe(fixture(__FILE__, "freeze_magic_comment_across_files_no_comment.rb")).chomp.should == "false"
+      end
     end
 
     it "produce different objects for literals with the same content in different files if they have different encodings" do
@@ -258,30 +263,45 @@ describe "Ruby String literals" do
 end
 
 describe "Ruby String interpolation" do
-  it "creates a String having an Encoding compatible with all components" do
-    a = "\u3042"
-    b = "abc".encode("binary")
-
-    str = "#{a} x #{b}"
+  it "permits an empty expression" do
+    s = "#{}" # rubocop:disable Lint/EmptyInterpolation
+    s.should.empty?
+    s.should_not.frozen?
+  end
 
-    str.should == "\xe3\x81\x82\x20\x78\x20\x61\x62\x63".force_encoding("utf-8")
-    str.encoding.should == Encoding::UTF_8
+  it "returns a string with the source encoding by default" do
+    "a#{"b"}c".encoding.should == Encoding::BINARY
+    eval('"a#{"b"}c"'.dup.force_encoding("us-ascii")).encoding.should == Encoding::US_ASCII
+    eval("# coding: US-ASCII \n 'a#{"b"}c'").encoding.should == Encoding::US_ASCII
   end
 
-  it "creates a String having the Encoding of the components when all are the same Encoding" do
-    a = "abc".force_encoding("euc-jp")
-    b = "def".force_encoding("euc-jp")
-    str = '"#{a} x #{b}"'.force_encoding("euc-jp")
+  it "returns a string with the source encoding, even if the components have another encoding" do
+    a = "abc".dup.force_encoding("euc-jp")
+    "#{a}".encoding.should == Encoding::BINARY
 
-    result = eval(str)
-    result.should == "\x61\x62\x63\x20\x78\x20\x64\x65\x66".force_encoding("euc-jp")
-    result.encoding.should == Encoding::EUC_JP
+    b = "abc".encode("utf-8")
+    "#{b}".encoding.should == Encoding::BINARY
   end
 
   it "raises an Encoding::CompatibilityError if the Encodings are not compatible" do
     a = "\u3042"
-    b = "\xff".force_encoding "binary"
+    b = "\xff".dup.force_encoding "binary"
+
+    -> { "#{a} #{b}" }.should.raise(Encoding::CompatibilityError)
+  end
+
+  it "creates a non-frozen String" do
+    code = <<~'RUBY'
+      "a#{6*7}c"
+    RUBY
+    eval(code).should_not.frozen?
+  end
 
-    -> { "#{a} #{b}" }.should raise_error(Encoding::CompatibilityError)
+  it "creates a non-frozen String when # frozen-string-literal: true is used" do
+    code = <<~'RUBY'
+      # frozen-string-literal: true
+      "a#{6*7}c"
+    RUBY
+    eval(code).should_not.frozen?
   end
 end
diff --git a/spec/ruby/language/super_spec.rb b/spec/ruby/language/super_spec.rb
index 66a1ec7592..f595d49395 100644
--- a/spec/ruby/language/super_spec.rb
+++ b/spec/ruby/language/super_spec.rb
@@ -70,7 +70,7 @@ describe "The super keyword" do
     SuperSpecs::S4::B.new.foo([],"test").should == ["B#foo(a,test)", "A#foo"]
   end
 
-  it "raises an error error when super method does not exist" do
+  it "raises an error when super method does not exist" do
     sup = Class.new
     sub_normal = Class.new(sup) do
       def foo
@@ -83,8 +83,8 @@ describe "The super keyword" do
       end
     end
 
-    -> {sub_normal.new.foo}.should raise_error(NoMethodError, /super/)
-    -> {sub_zsuper.new.foo}.should raise_error(NoMethodError, /super/)
+    -> {sub_normal.new.foo}.should.raise(NoMethodError, /super/)
+    -> {sub_zsuper.new.foo}.should.raise(NoMethodError, /super/)
   end
 
   it "uses given block even if arguments are passed explicitly" do
@@ -102,6 +102,37 @@ describe "The super keyword" do
     c2.new.m(:dump) { :value }.should == :value
   end
 
+  it "can pass an explicit block" do
+    c1 = Class.new do
+      def m(v)
+        yield(v)
+      end
+    end
+    c2 = Class.new(c1) do
+      def m(v)
+        block = -> w { yield(w + 'b') }
+        super(v, &block)
+      end
+    end
+
+    c2.new.m('a') { |x| x + 'c' }.should == 'abc'
+  end
+
+  it "can pass no block using &nil" do
+    c1 = Class.new do
+      def m(v)
+        block_given?
+      end
+    end
+    c2 = Class.new(c1) do
+      def m(v)
+        super(v, &nil)
+      end
+    end
+
+    c2.new.m('a') { raise }.should == false
+  end
+
   it "uses block argument given to method when used in a block" do
     c1 = Class.new do
       def m
@@ -169,7 +200,26 @@ describe "The super keyword" do
       end
     end
 
-    -> { klass.new.a(:a_called) }.should raise_error(RuntimeError)
+    -> { klass.new.a(:a_called) }.should.raise(RuntimeError)
+  end
+
+  it "is able to navigate to super, when a method is defined dynamically on the singleton class" do
+    foo_class = Class.new do
+      def bar
+        "bar"
+      end
+    end
+
+    mixin_module = Module.new do
+      def bar
+        "super_" + super
+      end
+    end
+
+    foo = foo_class.new
+    foo.singleton_class.define_method(:bar, mixin_module.instance_method(:bar))
+
+    foo.bar.should == "super_bar"
   end
 
   # Rubinius ticket github#157
@@ -262,6 +312,21 @@ describe "The super keyword" do
 
   it "without explicit arguments passes arguments and rest arguments" do
     SuperSpecs::ZSuperWithRestAndOthers::B.new.m(1, 2, 3, 4, 5).should == [3, 4, 5]
+    SuperSpecs::ZSuperWithRestAndOthers::B.new.m(1, 2).should == []
+  end
+
+  it "without explicit arguments passes arguments, rest arguments, and post arguments" do
+    SuperSpecs::ZSuperWithRestAndPost::B.new.m(1, 2, 3, 4, 5).should == [1, 2, 3]
+    SuperSpecs::ZSuperWithRestOthersAndPost::B.new.m(1, 2, 3, 4, 5).should == [2, 3, 4]
+    SuperSpecs::ZSuperWithRestAndPost::B.new.m(1, 2).should == []
+    SuperSpecs::ZSuperWithRestOthersAndPost::B.new.m(1, 2).should == []
+  end
+
+  it "without explicit arguments passes arguments, rest arguments including modifications, and post arguments" do
+    SuperSpecs::ZSuperWithRestAndPost::B.new.m_modified(1, 2, 3, 4, 5).should == [1, 14, 3]
+    SuperSpecs::ZSuperWithRestOthersAndPost::B.new.m_modified(1, 2, 3, 4, 5).should == [2, 14, 4]
+    SuperSpecs::ZSuperWithRestAndPost::B.new.m_modified(1, 2).should == [nil, 14]
+    SuperSpecs::ZSuperWithRestOthersAndPost::B.new.m_modified(1, 2).should == [nil, 14]
   end
 
   it "without explicit arguments passes arguments and rest arguments including any modifications" do
@@ -270,12 +335,23 @@ describe "The super keyword" do
 
   it "without explicit arguments that are '_'" do
     SuperSpecs::ZSuperWithUnderscores::B.new.m(1, 2).should == [1, 2]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m3(1, 2, 3).should == [1, 2, 3]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m4(1, 2, 3, 4).should == [1, 2, 3, 4]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m_default(1).should == [1]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m_default.should == [0]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m_pre_default_rest_post(1, 2, 3, 4, 5, 6, 7).should == [1, 2, 3, 4, 5, 6, 7]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m_rest(1, 2).should == [1, 2]
+    SuperSpecs::ZSuperWithUnderscores::B.new.m_kwrest(a: 1).should == {a: 1}
   end
 
   it "without explicit arguments that are '_' including any modifications" do
     SuperSpecs::ZSuperWithUnderscores::B.new.m_modified(1, 2).should == [14, 2]
   end
 
+  it "should pass method arguments when called within a closure" do
+    SuperSpecs::ZSuperInBlock::B.new.m(arg: 1).should == 1
+  end
+
   describe 'when using keyword arguments' do
     before :each do
       @req  = SuperSpecs::Keywords::RequiredArguments.new
@@ -385,4 +461,18 @@ describe "The super keyword" do
       @all.foo('a', b: 'b').should == [['a'], {b: 'b'}]
     end
   end
+
+  it "works in method definitions using **nil" do
+    parent = Class.new do
+      def m(*args, **kwargs)
+        [args, kwargs]
+      end
+    end
+    child = Class.new(parent) do
+      def m(*args, **nil)
+        super
+      end
+    end
+    child.new.m(1, 2).should == [[1, 2], {}]
+  end
 end
diff --git a/spec/ruby/language/symbol_spec.rb b/spec/ruby/language/symbol_spec.rb
index d6a41d3059..81fe06b50b 100644
--- a/spec/ruby/language/symbol_spec.rb
+++ b/spec/ruby/language/symbol_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 describe "A Symbol literal" do
   it "is a ':' followed by any number of valid characters" do
     a = :foo
-    a.should be_kind_of(Symbol)
+    a.should.is_a?(Symbol)
     a.inspect.should == ':foo'
   end
 
@@ -21,7 +21,7 @@ describe "A Symbol literal" do
       :_Foo,
       :&,
       :_9
-    ].each { |s| s.should be_kind_of(Symbol) }
+    ].each { |s| s.should.is_a?(Symbol) }
   end
 
   it "is a ':' followed by a single- or double-quoted string that may contain otherwise invalid characters" do
@@ -31,7 +31,7 @@ describe "A Symbol literal" do
       [:"foo #{1 + 1}", ':"foo 2"'],
       [:"foo\nbar",     ':"foo\nbar"'],
     ].each { |sym, str|
-      sym.should be_kind_of(Symbol)
+      sym.should.is_a?(Symbol)
       sym.inspect.should == str
     }
   end
@@ -42,22 +42,22 @@ describe "A Symbol literal" do
   end
 
   it "may contain '::' in the string" do
-    :'Some::Class'.should be_kind_of(Symbol)
+    :'Some::Class'.should.is_a?(Symbol)
   end
 
   it "is converted to a literal, unquoted representation if the symbol contains only valid characters" do
     a, b, c = :'foo', :'+', :'Foo__9'
-    a.should be_kind_of(Symbol)
+    a.should.is_a?(Symbol)
     a.inspect.should == ':foo'
-    b.should be_kind_of(Symbol)
+    b.should.is_a?(Symbol)
     b.inspect.should == ':+'
-    c.should be_kind_of(Symbol)
+    c.should.is_a?(Symbol)
     c.inspect.should == ':Foo__9'
   end
 
   it "can be created by the %s-delimited expression" do
     a, b = :'foo bar', %s{foo bar}
-    b.should be_kind_of(Symbol)
+    b.should.is_a?(Symbol)
     b.inspect.should == ':"foo bar"'
     b.should == a
   end
@@ -68,7 +68,7 @@ describe "A Symbol literal" do
       [:'a string', :'a string'],
       [:"#{var}", :"#{var}"]
     ].each { |a, b|
-      a.should equal(b)
+      a.should.equal?(b)
     }
   end
 
@@ -78,7 +78,7 @@ describe "A Symbol literal" do
 
   it "can be an empty string" do
     c = :''
-    c.should be_kind_of(Symbol)
+    c.should.is_a?(Symbol)
     c.inspect.should == ':""'
   end
 
@@ -96,11 +96,13 @@ describe "A Symbol literal" do
     %I{a b #{"c"}}.should == [:a, :b, :c]
   end
 
-  it "with invalid bytes raises an EncodingError at parse time" do
-    ScratchPad.record []
-    -> {
-      eval 'ScratchPad << 1; :"\xC3"'
-    }.should raise_error(EncodingError, /invalid/)
-    ScratchPad.recorded.should == []
+  ruby_bug "#20280", ""..."3.4" do
+    it "raises an SyntaxError at parse time when Symbol with invalid bytes" do
+      ScratchPad.record []
+      -> {
+        eval 'ScratchPad << 1; :"\xC3"'
+      }.should.raise(SyntaxError, /invalid symbol/)
+      ScratchPad.recorded.should == []
+    end
   end
 end
diff --git a/spec/ruby/language/throw_spec.rb b/spec/ruby/language/throw_spec.rb
index d723843688..73f64de17d 100644
--- a/spec/ruby/language/throw_spec.rb
+++ b/spec/ruby/language/throw_spec.rb
@@ -35,7 +35,7 @@ describe "The throw keyword" do
         throw :exit
       end
     end
-    $!.should be_nil
+    $!.should == nil
   end
 
   it "allows any object as its argument" do
@@ -45,7 +45,7 @@ describe "The throw keyword" do
   end
 
   it "does not convert strings to a symbol" do
-    -> { catch(:exit) { throw "exit" } }.should raise_error(ArgumentError)
+    -> { catch(:exit) { throw "exit" } }.should.raise(ArgumentError)
   end
 
   it "unwinds stack from within a method" do
@@ -64,8 +64,8 @@ describe "The throw keyword" do
   end
 
   it "raises an ArgumentError if outside of scope of a matching catch" do
-    -> { throw :test, 5 }.should raise_error(ArgumentError)
-    -> { catch(:different) { throw :test, 5 } }.should raise_error(ArgumentError)
+    -> { throw :test, 5 }.should.raise(ArgumentError)
+    -> { catch(:different) { throw :test, 5 } }.should.raise(ArgumentError)
   end
 
   it "raises an UncaughtThrowError if used to exit a thread" do
@@ -73,7 +73,7 @@ describe "The throw keyword" do
       t = Thread.new {
         -> {
           throw :what
-        }.should raise_error(UncaughtThrowError)
+        }.should.raise(UncaughtThrowError)
       }
       t.join
     end
diff --git a/spec/ruby/language/undef_spec.rb b/spec/ruby/language/undef_spec.rb
index 4e473b803f..98ecd99c21 100644
--- a/spec/ruby/language/undef_spec.rb
+++ b/spec/ruby/language/undef_spec.rb
@@ -14,35 +14,42 @@ describe "The undef keyword" do
       @undef_class.class_eval do
         undef meth
       end
-      -> { @obj.meth(5) }.should raise_error(NoMethodError)
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
     end
 
     it "with a simple symbol" do
       @undef_class.class_eval do
         undef :meth
       end
-      -> { @obj.meth(5) }.should raise_error(NoMethodError)
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
     end
 
     it "with a single quoted symbol" do
       @undef_class.class_eval do
         undef :'meth'
       end
-      -> { @obj.meth(5) }.should raise_error(NoMethodError)
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
     end
 
     it "with a double quoted symbol" do
       @undef_class.class_eval do
         undef :"meth"
       end
-      -> { @obj.meth(5) }.should raise_error(NoMethodError)
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
     end
 
-    it "with a interpolated symbol" do
+    it "with an interpolated symbol" do
       @undef_class.class_eval do
         undef :"#{'meth'}"
       end
-      -> { @obj.meth(5) }.should raise_error(NoMethodError)
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
+    end
+
+    it "with an interpolated symbol when interpolated expression is not a String literal" do
+      @undef_class.class_eval do
+        undef :"#{'meth'.to_sym}"
+      end
+      -> { @obj.meth(5) }.should.raise(NoMethodError)
     end
   end
 
@@ -62,8 +69,8 @@ describe "The undef keyword" do
   it "raises a NameError when passed a missing name" do
     Class.new do
       -> {
-         undef not_exist
-      }.should raise_error(NameError) { |e|
+        undef not_exist
+      }.should.raise(NameError) { |e|
         # a NameError and not a NoMethodError
         e.class.should == NameError
       }
diff --git a/spec/ruby/language/variables_spec.rb b/spec/ruby/language/variables_spec.rb
index 868603eb88..e01e03f01e 100644
--- a/spec/ruby/language/variables_spec.rb
+++ b/spec/ruby/language/variables_spec.rb
@@ -1,6 +1,51 @@
 require_relative '../spec_helper'
 require_relative 'fixtures/variables'
 
+describe "Evaluation order during assignment" do
+  context "with single assignment" do
+    it "evaluates from left to right" do
+      obj = VariablesSpecs::EvalOrder.new
+      obj.instance_eval do
+        foo[0] = a
+      end
+
+      obj.order.should == ["foo", "a", "foo[]="]
+    end
+  end
+
+  context "with multiple assignment" do
+    it "evaluates from left to right, receivers first then methods" do
+      obj = VariablesSpecs::EvalOrder.new
+      obj.instance_eval do
+        foo[0], bar.baz = a, b
+      end
+
+      obj.order.should == ["foo", "bar", "a", "b", "foo[]=", "bar.baz="]
+    end
+
+    it "can be used to swap variables with nested method calls" do
+      node = VariablesSpecs::EvalOrder.new.node
+
+      original_node = node
+      original_node_left = node.left
+      original_node_left_right = node.left.right
+
+      node.left, node.left.right, node = node.left.right, node, node.left
+      # Should evaluate in the order of:
+      # LHS: node, node.left(original_node_left)
+      # RHS: original_node_left_right, original_node, original_node_left
+      # Ops:
+      # * node(original_node), original_node.left = original_node_left_right
+      # * original_node_left.right = original_node
+      # * node = original_node_left
+
+      node.should == original_node_left
+      node.right.should == original_node
+      node.right.left.should == original_node_left_right
+    end
+  end
+end
+
 describe "Multiple assignment" do
   context "with a single RHS value" do
     it "assigns a simple MLHS" do
@@ -46,7 +91,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign single RHS")
       x.should_receive(:to_ary).and_return(1)
 
-      -> { a, b, c = x }.should raise_error(TypeError)
+      -> { a, b, c = x }.should.raise(TypeError)
     end
 
     it "does not call #to_a to convert an Object RHS when assigning a simple MLHS" do
@@ -77,7 +122,7 @@ describe "Multiple assignment" do
       ary = [1, 2]
 
       x = (a, b = ary)
-      x.should equal(ary)
+      x.should.equal?(ary)
     end
 
     it "returns the RHS when it is an Array subclass" do
@@ -85,7 +130,7 @@ describe "Multiple assignment" do
       ary = cls.new [1, 2]
 
       x = (a, b = ary)
-      x.should equal(ary)
+      x.should.equal?(ary)
     end
 
     it "does not call #to_ary on an Array subclass instance" do
@@ -127,7 +172,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat")
       x.should_receive(:to_ary).and_return(1)
 
-      -> { *a = x }.should raise_error(TypeError)
+      -> { *a = x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary on an Array subclass" do
@@ -144,8 +189,8 @@ describe "Multiple assignment" do
       ary = cls.new [1, 2]
 
       x = (*a = ary)
-      x.should equal(ary)
-      a.should be_an_instance_of(Array)
+      x.should.equal?(ary)
+      a.should.instance_of?(Array)
     end
 
     it "calls #to_ary to convert an Object RHS with MLHS" do
@@ -160,7 +205,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat")
       x.should_receive(:to_ary).and_return(1)
 
-      -> { a, *b, c = x }.should raise_error(TypeError)
+      -> { a, *b, c = x }.should.raise(TypeError)
     end
 
     it "does not call #to_a to convert an Object RHS with a MLHS" do
@@ -256,7 +301,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign attributes")
       x.should_receive(:m).and_return(y)
 
-      -> { a, b = x.m }.should raise_error(TypeError)
+      -> { a, b = x.m }.should.raise(TypeError)
     end
 
     it "assigns values from a RHS method call with receiver and arguments" do
@@ -287,8 +332,13 @@ describe "Multiple assignment" do
 
     it "assigns indexed elements" do
       a = []
-      a[1], a[2] = 1
-      a.should == [nil, 1, nil]
+      a[1], a[2] = 1, 2
+      a.should == [nil, 1, 2]
+
+      # with splatted argument
+      a = []
+      a[*[1]], a[*[2]] = 1, 2
+      a.should == [nil, 1, 2]
     end
 
     it "assigns constants" do
@@ -296,6 +346,9 @@ describe "Multiple assignment" do
         SINGLE_RHS_1, SINGLE_RHS_2 = 1
         [SINGLE_RHS_1, SINGLE_RHS_2].should == [1, nil]
       end
+    ensure
+      VariableSpecs.send(:remove_const, :SINGLE_RHS_1)
+      VariableSpecs.send(:remove_const, :SINGLE_RHS_2)
     end
   end
 
@@ -310,11 +363,22 @@ describe "Multiple assignment" do
       a.should == []
     end
 
-    it "calls #to_a to convert nil to an empty Array" do
-      nil.should_receive(:to_a).and_return([])
+    ruby_version_is "4.0" do
+      it "converts nil to empty array without calling a method" do
+        nil.should_not_receive(:to_a)
 
-      (*a = *nil).should == []
-      a.should == []
+        (*a = *nil).should == []
+        a.should == []
+      end
+    end
+
+    ruby_version_is ""..."4.0"  do
+      it "calls #to_a to convert nil to an empty Array" do
+        nil.should_receive(:to_a).and_return([])
+
+        (*a = *nil).should == []
+        a.should == []
+      end
     end
 
     it "does not call #to_a on an Array" do
@@ -329,7 +393,7 @@ describe "Multiple assignment" do
       ary = [1, 2]
 
       (a = *ary).should == [1, 2]
-      a.should_not equal(ary)
+      a.should_not.equal?(ary)
     end
 
     it "does not call #to_a on an Array subclass" do
@@ -348,10 +412,20 @@ describe "Multiple assignment" do
       x = (a = *ary)
 
       x.should == [1, 2]
-      x.should be_an_instance_of(Array)
+      x.should.instance_of?(Array)
 
       a.should == [1, 2]
-      a.should be_an_instance_of(Array)
+      a.should.instance_of?(Array)
+    end
+
+    it "unfreezes the array returned from calling 'to_a' on the splatted value" do
+      obj = Object.new
+      def obj.to_a
+        [1,2].freeze
+      end
+      res = *obj
+      res.should == [1,2]
+      res.should_not.frozen?
     end
 
     it "consumes values for an anonymous splat" do
@@ -407,7 +481,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign RHS splat")
       x.should_receive(:to_a).and_return(1)
 
-      -> { *a = *x }.should raise_error(TypeError)
+      -> { *a = *x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert an Object RHS with a single splat LHS" do
@@ -453,7 +527,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat")
       x.should_receive(:to_a).and_return(1)
 
-      -> { a = *x }.should raise_error(TypeError)
+      -> { a = *x }.should.raise(TypeError)
     end
 
     it "calls #to_a to convert an Object splat RHS when assigned to a simple MLHS" do
@@ -468,7 +542,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat")
       x.should_receive(:to_a).and_return(1)
 
-      -> { a, b, c = *x }.should raise_error(TypeError)
+      -> { a, b, c = *x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert an Object splat RHS when assigned to a simple MLHS" do
@@ -491,7 +565,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat")
       x.should_receive(:to_a).and_return(1)
 
-      -> { a, *b, c = *x }.should raise_error(TypeError)
+      -> { a, *b, c = *x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert an Object RHS with a MLHS" do
@@ -524,6 +598,8 @@ describe "Multiple assignment" do
         (*SINGLE_SPLATTED_RHS) = *1
         SINGLE_SPLATTED_RHS.should == [1]
       end
+    ensure
+      VariableSpecs.send(:remove_const, :SINGLE_SPLATTED_RHS)
     end
   end
 
@@ -569,7 +645,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat MRHS")
       x.should_receive(:to_a).and_return(1)
 
-      -> { a, *b = 1, *x }.should raise_error(TypeError)
+      -> { a, *b = 1, *x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert a splatted Object as part of a MRHS with a splat MRHS" do
@@ -592,7 +668,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign splat MRHS")
       x.should_receive(:to_a).and_return(1)
 
-      -> { a, *b = *x, 1 }.should raise_error(TypeError)
+      -> { a, *b = *x, 1 }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert a splatted Object with a splat MRHS" do
@@ -641,7 +717,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign mixed RHS")
       x.should_receive(:to_ary).and_return(x)
 
-      -> { a, (b, c), d = 1, x, 3, 4 }.should raise_error(TypeError)
+      -> { a, (b, c), d = 1, x, 3, 4 }.should.raise(TypeError)
     end
 
     it "calls #to_a to convert a splatted Object value in a MRHS" do
@@ -665,7 +741,7 @@ describe "Multiple assignment" do
       x = mock("multi-assign mixed splatted RHS")
       x.should_receive(:to_ary).and_return(x)
 
-      -> { a, *b, (c, d) = 1, 2, 3, *x }.should raise_error(TypeError)
+      -> { a, *b, (c, d) = 1, 2, 3, *x }.should.raise(TypeError)
     end
 
     it "does not call #to_ary to convert an Object when the position receiving the value is a simple variable" do
@@ -705,12 +781,27 @@ describe "Multiple assignment" do
       x.should == [1, 2, 3, 4, 5]
     end
 
+    it "can be used to swap array elements" do
+      a = [1, 2]
+      a[0], a[1] = a[1], a[0]
+      a.should == [2, 1]
+    end
+
+    it "can be used to swap range of array elements" do
+      a = [1, 2, 3, 4]
+      a[0, 2], a[2, 2] = a[2, 2], a[0, 2]
+      a.should == [3, 4, 1, 2]
+    end
+
     it "assigns RHS values to LHS constants" do
       module VariableSpecs
         MRHS_VALUES_1, MRHS_VALUES_2 = 1, 2
         MRHS_VALUES_1.should == 1
         MRHS_VALUES_2.should == 2
       end
+    ensure
+      VariableSpecs.send(:remove_const, :MRHS_VALUES_1)
+      VariableSpecs.send(:remove_const, :MRHS_VALUES_2)
     end
 
     it "assigns all RHS values as an array to a single LHS constant" do
@@ -718,6 +809,8 @@ describe "Multiple assignment" do
         MRHS_VALUES = 1, 2, 3
         MRHS_VALUES.should == [1, 2, 3]
       end
+    ensure
+      VariableSpecs.send(:remove_const, :MRHS_VALUES)
     end
   end
 
@@ -760,29 +853,78 @@ describe "A local variable assigned only within a conditional block" do
 end
 
 describe 'Local variable shadowing' do
-  ruby_version_is ""..."2.6" do
-    it "leads to warning in verbose mode" do
-      -> do
-        eval <<-CODE
-          a = [1, 2, 3]
-          a.each { |a| a = 3 }
-        CODE
-      end.should complain(/shadowing outer local variable/, verbose: true)
+  it "does not warn in verbose mode" do
+    result = nil
+
+    -> do
+      eval <<-CODE
+        a = [1, 2, 3]
+        result = a.map { |a| a = 3 }
+      CODE
+    end.should_not complain(verbose: true)
+
+    result.should == [3, 3, 3]
+  end
+end
+
+describe 'Allowed characters' do
+  it 'allows non-ASCII lowercased characters at the beginning' do
+    result = nil
+
+    eval <<-CODE
+      def test
+        μ = 1
+      end
+
+      result = test
+    CODE
+
+    result.should == 1
+  end
+
+  it 'parses a non-ASCII upcased character as a constant identifier' do
+    -> do
+      eval <<-CODE
+        def test
+          ἍBB = 1
+        end
+      CODE
+    end.should.raise(SyntaxError, /dynamic constant assignment/)
+  end
+end
+
+describe "Instance variables" do
+  context "when instance variable is uninitialized" do
+    it "doesn't warn about accessing uninitialized instance variable" do
+      obj = Object.new
+      def obj.foobar; a = @a; end
+
+      -> { obj.foobar }.should_not complain(verbose: true)
+    end
+
+    it "doesn't warn at lazy initialization" do
+      obj = Object.new
+      def obj.foobar; @a ||= 42; end
+
+      -> { obj.foobar }.should_not complain(verbose: true)
     end
   end
 
-  ruby_version_is "2.6" do
-    it "does not warn in verbose mode" do
-      result = nil
+  describe "global variable" do
+    context "when global variable is uninitialized" do
+      it "warns about accessing uninitialized global variable in verbose mode" do
+        obj = Object.new
+        def obj.foobar; a = $specs_uninitialized_global_variable; end
 
-      -> do
-        eval <<-CODE
-          a = [1, 2, 3]
-          result = a.map { |a| a = 3 }
-        CODE
-      end.should_not complain(verbose: true)
+        -> { obj.foobar }.should complain(/warning: global variable [`']\$specs_uninitialized_global_variable' not initialized/, verbose: true)
+      end
+
+      it "doesn't warn at lazy initialization" do
+        obj = Object.new
+        def obj.foobar; $specs_uninitialized_global_variable_lazy ||= 42; end
 
-      result.should == [3, 3, 3]
+        -> { obj.foobar }.should_not complain(verbose: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/language/while_spec.rb b/spec/ruby/language/while_spec.rb
index e172453ca6..b9bf32047d 100644
--- a/spec/ruby/language/while_spec.rb
+++ b/spec/ruby/language/while_spec.rb
@@ -88,7 +88,7 @@ describe "The while expression" do
           break if c
           c = false
         )
-    end.should be_nil
+    end.should == nil
   end
 
   it "stops running body if interrupted by break in a begin ... end element op-assign-or value" do
@@ -99,7 +99,7 @@ describe "The while expression" do
         break if c
         c = false
       end
-    end.should be_nil
+    end.should == nil
   end
 
   it "stops running body if interrupted by break in a parenthesized element op-assign value" do
@@ -111,7 +111,7 @@ describe "The while expression" do
           break if c
           c = false
         )
-    end.should be_nil
+    end.should == nil
     a.should == [1, 2]
   end
 
@@ -123,7 +123,7 @@ describe "The while expression" do
         break if c
         c = false
       end
-    end.should be_nil
+    end.should == nil
     a.should == [1, 2]
   end
 
@@ -139,7 +139,7 @@ describe "The while expression" do
           break unless d
           d = false
         )
-    end.should be_nil
+    end.should == nil
   end
 
   it "stops running body if interrupted by break with unless in a begin ... end attribute op-assign-or value" do
@@ -153,7 +153,7 @@ describe "The while expression" do
         break unless d
         d = false
       end
-    end.should be_nil
+    end.should == nil
   end
 
   it "stops running body if interrupted by break in a parenthesized attribute op-assign-or value" do
@@ -168,7 +168,7 @@ describe "The while expression" do
           break if c
           c = false
         )
-    end.should be_nil
+    end.should == nil
   end
 
   it "stops running body if interrupted by break in a begin ... end attribute op-assign-or value" do
@@ -182,7 +182,7 @@ describe "The while expression" do
         break if c
         c = false
       end
-    end.should be_nil
+    end.should == nil
   end
 
   it "returns value passed to break if interrupted by break" do
diff --git a/spec/ruby/language/yield_spec.rb b/spec/ruby/language/yield_spec.rb
index 5fad7cb176..3173f41b0c 100644
--- a/spec/ruby/language/yield_spec.rb
+++ b/spec/ruby/language/yield_spec.rb
@@ -13,7 +13,7 @@ describe "The yield call" do
 
   describe "taking no arguments" do
     it "raises a LocalJumpError when the method is not passed a block" do
-      -> { @y.z }.should raise_error(LocalJumpError)
+      -> { @y.z }.should.raise(LocalJumpError)
     end
 
     it "ignores assignment to the explicit block argument and calls the passed block" do
@@ -28,7 +28,7 @@ describe "The yield call" do
   describe "taking a single argument" do
     describe "when no block is given" do
       it "raises a LocalJumpError" do
-        -> { @y.s(1) }.should raise_error(LocalJumpError)
+        -> { @y.s(1) }.should.raise(LocalJumpError)
       end
     end
 
@@ -48,6 +48,12 @@ describe "The yield call" do
       it "passes a single, multi-value Array" do
         @y.s([1, 2, 3]) { |*a| a }.should == [[1, 2, 3]]
       end
+
+      describe "with optional argument" do
+        it "does not destructure a single array argument" do
+          @y.s([1, 2, 3]) { |a = 99| a }.should == [1, 2, 3]
+        end
+      end
     end
 
     describe "yielding to a lambda" do
@@ -70,20 +76,20 @@ describe "The yield call" do
       it "raises an ArgumentError if too few arguments are passed" do
         -> {
           @y.s(1, &-> a, b { [a,b] })
-        }.should raise_error(ArgumentError)
+        }.should.raise(ArgumentError)
       end
 
       it "should not destructure an Array into multiple arguments" do
         -> {
           @y.s([1, 2], &-> a, b { [a,b] })
-        }.should raise_error(ArgumentError)
+        }.should.raise(ArgumentError)
       end
     end
   end
 
   describe "taking multiple arguments" do
     it "raises a LocalJumpError when the method is not passed a block" do
-      -> { @y.m(1, 2, 3) }.should raise_error(LocalJumpError)
+      -> { @y.m(1, 2, 3) }.should.raise(LocalJumpError)
     end
 
     it "passes the arguments to the block" do
@@ -97,19 +103,19 @@ describe "The yield call" do
     it "raises an ArgumentError if too many arguments are passed to a lambda" do
       -> {
         @y.m(1, 2, 3, &-> a { })
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
 
     it "raises an ArgumentError if too few arguments are passed to a lambda" do
       -> {
         @y.m(1, 2, 3, &-> a, b, c, d { })
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
   describe "taking a single splatted argument" do
     it "raises a LocalJumpError when the method is not passed a block" do
-      -> { @y.r(0) }.should raise_error(LocalJumpError)
+      -> { @y.r(0) }.should.raise(LocalJumpError)
     end
 
     it "passes a single value" do
@@ -141,7 +147,7 @@ describe "The yield call" do
 
   describe "taking multiple arguments with a splat" do
     it "raises a LocalJumpError when the method is not passed a block" do
-      -> { @y.rs(1, 2, [3, 4]) }.should raise_error(LocalJumpError)
+      -> { @y.rs(1, 2, [3, 4]) }.should.raise(LocalJumpError)
     end
 
     it "passes the arguments to the block" do
@@ -166,7 +172,7 @@ describe "The yield call" do
 
   describe "taking matching arguments with splats and post args" do
     it "raises a LocalJumpError when the method is not passed a block" do
-      -> { @y.rs(1, 2, [3, 4]) }.should raise_error(LocalJumpError)
+      -> { @y.rs(1, 2, [3, 4]) }.should.raise(LocalJumpError)
     end
 
     it "passes the arguments to the block" do
@@ -183,5 +189,38 @@ describe "The yield call" do
   it "uses captured block of a block used in define_method" do
     @y.deep(2).should == 4
   end
+end
+
+describe "Using yield in a singleton class literal" do
+  it 'raises a SyntaxError' do
+    code = <<~RUBY
+      class << Object.new
+        yield
+      end
+    RUBY
+
+    -> { eval(code) }.should.raise(SyntaxError, /Invalid yield/)
+  end
+end
 
+describe "Using yield in non-lambda block" do
+  it 'raises a SyntaxError' do
+    code = <<~RUBY
+        1.times { yield }
+      RUBY
+
+    -> { eval(code) }.should.raise(SyntaxError, /Invalid yield/)
+  end
+end
+
+describe "Using yield in a module literal" do
+  it 'raises a SyntaxError' do
+    code = <<~RUBY
+      module YieldSpecs::ModuleWithYield
+        yield
+      end
+    RUBY
+
+    -> { eval(code) }.should.raise(SyntaxError, /Invalid yield/)
+  end
 end
diff --git a/spec/ruby/library/English/English_spec.rb b/spec/ruby/library/English/English_spec.rb
index f6153ec7c9..bdc3774608 100644
--- a/spec/ruby/library/English/English_spec.rb
+++ b/spec/ruby/library/English/English_spec.rb
@@ -7,26 +7,26 @@ describe "English" do
     begin
       raise "error"
     rescue
-      $ERROR_INFO.should_not be_nil
+      $ERROR_INFO.should_not == nil
       $ERROR_INFO.should == $!
     end
-    $ERROR_INFO.should be_nil
+    $ERROR_INFO.should == nil
   end
 
   it "aliases $ERROR_POSITION to $@" do
     begin
       raise "error"
     rescue
-      $ERROR_POSITION.should_not be_nil
+      $ERROR_POSITION.should_not == nil
       $ERROR_POSITION.should == $@
     end
-    $ERROR_POSITION.should be_nil
+    $ERROR_POSITION.should == nil
   end
 
   it "aliases $FS to $;" do
     original = $;
     suppress_warning {$; = ","}
-    $FS.should_not be_nil
+    $FS.should_not == nil
     $FS.should == $;
     suppress_warning {$; = original}
   end
@@ -34,7 +34,7 @@ describe "English" do
   it "aliases $FIELD_SEPARATOR to $;" do
     original = $;
     suppress_warning {$; = ","}
-    $FIELD_SEPARATOR.should_not be_nil
+    $FIELD_SEPARATOR.should_not == nil
     $FIELD_SEPARATOR.should == $;
     suppress_warning {$; = original}
   end
@@ -42,7 +42,7 @@ describe "English" do
   it "aliases $OFS to $," do
     original = $,
     suppress_warning {$, = "|"}
-    $OFS.should_not be_nil
+    $OFS.should_not == nil
     $OFS.should == $,
     suppress_warning {$, = original}
   end
@@ -50,122 +50,112 @@ describe "English" do
   it "aliases $OUTPUT_FIELD_SEPARATOR to $," do
     original = $,
     suppress_warning {$, = "|"}
-    $OUTPUT_FIELD_SEPARATOR.should_not be_nil
+    $OUTPUT_FIELD_SEPARATOR.should_not == nil
     $OUTPUT_FIELD_SEPARATOR.should == $,
     suppress_warning {$, = original}
   end
 
   it "aliases $RS to $/" do
-    $RS.should_not be_nil
+    $RS.should_not == nil
     $RS.should == $/
   end
 
   it "aliases $INPUT_RECORD_SEPARATOR to $/" do
-    $INPUT_RECORD_SEPARATOR.should_not be_nil
+    $INPUT_RECORD_SEPARATOR.should_not == nil
     $INPUT_RECORD_SEPARATOR.should == $/
   end
 
   it "aliases $ORS to $\\" do
     original = $\
-    $\ = "\t"
-    $ORS.should_not be_nil
+    suppress_warning {$\ = "\t"}
+    $ORS.should_not == nil
     $ORS.should == $\
-    $\ = original
+    suppress_warning {$\ = original}
   end
 
   it "aliases $OUTPUT_RECORD_SEPARATOR to $\\" do
     original = $\
-    $\ = "\t"
-    $OUTPUT_RECORD_SEPARATOR.should_not be_nil
+    suppress_warning {$\ = "\t"}
+    $OUTPUT_RECORD_SEPARATOR.should_not == nil
     $OUTPUT_RECORD_SEPARATOR.should == $\
-    $\ = original
+    suppress_warning {$\ = original}
   end
 
   it "aliases $INPUT_LINE_NUMBER to $." do
-    $INPUT_LINE_NUMBER.should_not be_nil
+    $INPUT_LINE_NUMBER.should_not == nil
     $INPUT_LINE_NUMBER.should == $.
   end
 
   it "aliases $NR to $." do
-    $NR.should_not be_nil
+    $NR.should_not == nil
     $NR.should == $.
   end
 
   it "aliases $LAST_READ_LINE to $_ needs to be reviewed for spec completeness"
 
   it "aliases $DEFAULT_OUTPUT to $>" do
-    $DEFAULT_OUTPUT.should_not be_nil
+    $DEFAULT_OUTPUT.should_not == nil
     $DEFAULT_OUTPUT.should == $>
   end
 
   it "aliases $DEFAULT_INPUT to $<" do
-    $DEFAULT_INPUT.should_not be_nil
+    $DEFAULT_INPUT.should_not == nil
     $DEFAULT_INPUT.should == $<
   end
 
   it "aliases $PID to $$" do
-    $PID.should_not be_nil
+    $PID.should_not == nil
     $PID.should == $$
   end
 
   it "aliases $PID to $$" do
-    $PID.should_not be_nil
+    $PID.should_not == nil
     $PID.should == $$
   end
 
   it "aliases $PROCESS_ID to $$" do
-    $PROCESS_ID.should_not be_nil
+    $PROCESS_ID.should_not == nil
     $PROCESS_ID.should == $$
   end
 
   it "aliases $CHILD_STATUS to $?" do
     ruby_exe('exit 0')
-    $CHILD_STATUS.should_not be_nil
+    $CHILD_STATUS.should_not == nil
     $CHILD_STATUS.should == $?
   end
 
   it "aliases $LAST_MATCH_INFO to $~" do
     /c(a)t/ =~ "cat"
-    $LAST_MATCH_INFO.should_not be_nil
+    $LAST_MATCH_INFO.should_not == nil
     $LAST_MATCH_INFO.should == $~
   end
 
-  it "aliases $IGNORECASE to $=" do
-    $VERBOSE, verbose = nil, $VERBOSE
-    begin
-      $IGNORECASE.should_not be_nil
-      $IGNORECASE.should == $=
-    ensure
-      $VERBOSE = verbose
-    end
-  end
-
   it "aliases $ARGV to $*" do
-    $ARGV.should_not be_nil
+    $ARGV.should_not == nil
     $ARGV.should == $*
   end
 
   it "aliases $MATCH to $&" do
     /c(a)t/ =~ "cat"
-    $MATCH.should_not be_nil
+    $MATCH.should_not == nil
     $MATCH.should == $&
   end
 
   it "aliases $PREMATCH to $`" do
     /c(a)t/ =~ "cat"
-    $PREMATCH.should_not be_nil
+    $PREMATCH.should_not == nil
     $PREMATCH.should == $`
   end
 
   it "aliases $POSTMATCH to $'" do
     /c(a)t/ =~ "cat"
-    $POSTMATCH.should_not be_nil
+    $POSTMATCH.should_not == nil
     $POSTMATCH.should == $'
   end
 
   it "aliases $LAST_PAREN_MATCH to $+" do
     /c(a)t/ =~ "cat"
-    $LAST_PAREN_MATCH.should_not be_nil
+    $LAST_PAREN_MATCH.should_not == nil
     $LAST_PAREN_MATCH.should == $+
   end
 end
diff --git a/spec/ruby/library/English/alias_spec.rb b/spec/ruby/library/English/alias_spec.rb
new file mode 100644
index 0000000000..3ff92f964d
--- /dev/null
+++ b/spec/ruby/library/English/alias_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+require 'English'
+
+describe "English" do
+  it "aliases $! to $ERROR_INFO and $ERROR_INFO still returns an Exception with a backtrace" do
+    exception = (1 / 0 rescue $ERROR_INFO)
+    exception.should.is_a?(Exception)
+    exception.backtrace.should.is_a?(Array)
+  end
+
+  it "aliases $@ to $ERROR_POSITION and $ERROR_POSITION still returns a backtrace" do
+    (1 / 0 rescue $ERROR_POSITION).should.is_a?(Array)
+  end
+end
diff --git a/spec/ruby/library/base64/decode64_spec.rb b/spec/ruby/library/base64/decode64_spec.rb
index 3b81203588..6dd33dddfe 100644
--- a/spec/ruby/library/base64/decode64_spec.rb
+++ b/spec/ruby/library/base64/decode64_spec.rb
@@ -6,4 +6,24 @@ describe "Base64#decode64" do
   it "returns the Base64-decoded version of the given string" do
     Base64.decode64("U2VuZCByZWluZm9yY2VtZW50cw==\n").should == "Send reinforcements"
   end
+
+  it "returns the Base64-decoded version of the given shared string" do
+    Base64.decode64("base64: U2VuZCByZWluZm9yY2VtZW50cw==\n".split(" ").last).should == "Send reinforcements"
+  end
+
+  it "returns the Base64-decoded version of the given string with wrong padding" do
+    Base64.decode64("XU2VuZCByZWluZm9yY2VtZW50cw===").should == "]M\x95\xB9\x90\x81\xC9\x95\xA5\xB9\x99\xBD\xC9\x8D\x95\xB5\x95\xB9\xD1\xCC".b
+  end
+
+  it "returns the Base64-decoded version of the given string that contains an invalid character" do
+    Base64.decode64("%3D").should == "\xDC".b
+  end
+
+  it "returns a binary encoded string" do
+    Base64.decode64("SEk=").encoding.should == Encoding::BINARY
+  end
+
+  it "decodes without padding suffix ==" do
+    Base64.decode64("eyJrZXkiOnsibiI6InR0dCJ9fQ").should == "{\"key\":{\"n\":\"ttt\"}}"
+  end
 end
diff --git a/spec/ruby/library/base64/encode64_spec.rb b/spec/ruby/library/base64/encode64_spec.rb
index 91ac41bed0..64de6257bc 100644
--- a/spec/ruby/library/base64/encode64_spec.rb
+++ b/spec/ruby/library/base64/encode64_spec.rb
@@ -11,4 +11,13 @@ describe "Base64#encode64" do
   it "returns the Base64-encoded version of the given string" do
     Base64.encode64('Send reinforcements').should == "U2VuZCByZWluZm9yY2VtZW50cw==\n"
   end
+
+  it "returns the Base64-encoded version of the given shared string" do
+    Base64.encode64("Now is the time for all good coders\nto learn Ruby".split("\n").last).should ==
+      "dG8gbGVhcm4gUnVieQ==\n"
+  end
+
+  it "returns a US_ASCII encoded string" do
+    Base64.encode64("HI").encoding.should == Encoding::US_ASCII
+  end
 end
diff --git a/spec/ruby/library/base64/strict_decode64_spec.rb b/spec/ruby/library/base64/strict_decode64_spec.rb
new file mode 100644
index 0000000000..7b52f0c922
--- /dev/null
+++ b/spec/ruby/library/base64/strict_decode64_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+
+require 'base64'
+
+describe "Base64#strict_decode64" do
+  it "returns the Base64-decoded version of the given string" do
+    Base64.strict_decode64("U2VuZCByZWluZm9yY2VtZW50cw==").should == "Send reinforcements"
+  end
+
+  it "returns the Base64-decoded version of the given shared string" do
+    Base64.strict_decode64("base64: U2VuZCByZWluZm9yY2VtZW50cw==".split(" ").last).should == "Send reinforcements"
+  end
+
+  it "raises ArgumentError when the given string contains CR" do
+    -> do
+      Base64.strict_decode64("U2VuZCByZWluZm9yY2VtZW50cw==\r")
+    end.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError when the given string contains LF" do
+    -> do
+      Base64.strict_decode64("U2VuZCByZWluZm9yY2VtZW50cw==\n")
+    end.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError when the given string has wrong padding" do
+    -> do
+      Base64.strict_decode64("=U2VuZCByZWluZm9yY2VtZW50cw==")
+    end.should.raise(ArgumentError)
+  end
+
+  it "raises ArgumentError when the given string contains an invalid character" do
+    -> do
+      Base64.strict_decode64("%3D")
+    end.should.raise(ArgumentError)
+  end
+
+  it "returns a binary encoded string" do
+    Base64.strict_decode64("SEk=").encoding.should == Encoding::BINARY
+  end
+end
diff --git a/spec/ruby/library/base64/strict_encode64_spec.rb b/spec/ruby/library/base64/strict_encode64_spec.rb
new file mode 100644
index 0000000000..7cabcf190c
--- /dev/null
+++ b/spec/ruby/library/base64/strict_encode64_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+
+require 'base64'
+
+describe "Base64#strict_encode64" do
+  it "returns the Base64-encoded version of the given string" do
+    Base64.strict_encode64("Now is the time for all good coders\nto learn Ruby").should ==
+      "Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4gUnVieQ=="
+  end
+
+  it "returns the Base64-encoded version of the given shared string" do
+    Base64.strict_encode64("Now is the time for all good coders\nto learn Ruby".split("\n").last).should ==
+      "dG8gbGVhcm4gUnVieQ=="
+  end
+
+  it "returns a US_ASCII encoded string" do
+    Base64.strict_encode64("HI").encoding.should == Encoding::US_ASCII
+  end
+end
diff --git a/spec/ruby/library/bigdecimal/BigDecimal_spec.rb b/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
index e1e6fe9fb1..6adebabe84 100644
--- a/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
+++ b/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
@@ -10,7 +10,7 @@ end
 describe "Kernel#BigDecimal" do
 
   it "creates a new object of class BigDecimal" do
-    BigDecimal("3.14159").should be_kind_of(BigDecimal)
+    BigDecimal("3.14159").should.is_a?(BigDecimal)
     (0..9).each {|i|
       BigDecimal("1#{i}").should == 10 + i
       BigDecimal("-1#{i}").should == -10 - i
@@ -24,106 +24,108 @@ describe "Kernel#BigDecimal" do
     }
   end
 
+  it "BigDecimal(Rational) with bigger-than-double numerator" do
+    rational = 99999999999999999999/100r
+    rational.numerator.should > 2**64
+    BigDecimal(rational, 100).to_s.should == "0.99999999999999999999e18"
+  end
+
   it "accepts significant digits >= given precision" do
-    BigDecimal("3.1415923", 10).precs[1].should >= 10
+    BigDecimal("3.1415923", 10).should == BigDecimal("3.1415923")
   end
 
   it "determines precision from initial value" do
     pi_string = "3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593014782083152134043"
-    BigDecimal(pi_string).precs[1].should >= pi_string.size-1
+    BigDecimal(pi_string).precision.should == pi_string.size-1
   end
 
-  it "ignores leading whitespace" do
-    BigDecimal("  \t\n \r1234").should == BigDecimal("1234")
-    BigDecimal("  \t\n \rNaN   \n").nan?.should == true
+  it "ignores leading and trailing whitespace" do
+    BigDecimal("  \t\n \r1234\t\r\n ").should == BigDecimal("1234")
+    BigDecimal("  \t\n \rNaN   \n").should.nan?
     BigDecimal("  \t\n \rInfinity   \n").infinite?.should == 1
     BigDecimal("  \t\n \r-Infinity   \n").infinite?.should == -1
   end
 
-  ruby_version_is ""..."2.6" do
-    it "ignores trailing garbage" do
-      BigDecimal("123E45ruby").should == BigDecimal("123E45")
-      BigDecimal("123x45").should == BigDecimal("123")
-      BigDecimal("123.4%E5").should == BigDecimal("123.4")
-      BigDecimal("1E2E3E4E5E").should == BigDecimal("100")
-    end
+  it "coerces the value argument with #to_str" do
+    initial = mock("value")
+    initial.should_receive(:to_str).and_return("123")
+    BigDecimal(initial).should == BigDecimal("123")
   end
 
-  ruby_version_is "2.6" do
-    it "does not ignores trailing garbage" do
-      -> { BigDecimal("123E45ruby") }.should raise_error(ArgumentError)
-      -> { BigDecimal("123x45") }.should raise_error(ArgumentError)
-      -> { BigDecimal("123.4%E5") }.should raise_error(ArgumentError)
-      -> { BigDecimal("1E2E3E4E5E") }.should raise_error(ArgumentError)
-    end
+  it "does not ignores trailing garbage" do
+    -> { BigDecimal("123E45ruby") }.should.raise(ArgumentError)
+    -> { BigDecimal("123x45") }.should.raise(ArgumentError)
+    -> { BigDecimal("123.4%E5") }.should.raise(ArgumentError)
+    -> { BigDecimal("1E2E3E4E5E") }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError for invalid strings" do
-    -> { BigDecimal("ruby") }.should raise_error(ArgumentError)
-    -> { BigDecimal("  \t\n \r-\t\t\tInfinity   \n") }.should raise_error(ArgumentError)
+    -> { BigDecimal("ruby") }.should.raise(ArgumentError)
+    -> { BigDecimal("  \t\n \r-\t\t\tInfinity   \n") }.should.raise(ArgumentError)
   end
 
   it "allows omitting the integer part" do
     BigDecimal(".123").should == BigDecimal("0.123")
   end
 
-  ruby_version_is ""..."2.6" do
-    it "allows for underscores in all parts" do
-      reference = BigDecimal("12345.67E89")
-
-      BigDecimal("12_345.67E89").should == reference
-      BigDecimal("1_2_3_4_5_._6____7_E89").should == reference
-      BigDecimal("12345_.67E_8__9_").should == reference
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "process underscores as Float()" do
-      reference = BigDecimal("12345.67E89")
+  it "process underscores as Float()" do
+    reference = BigDecimal("12345.67E89")
 
-      BigDecimal("12_345.67E89").should == reference
-      -> { BigDecimal("1_2_3_4_5_._6____7_E89") }.should raise_error(ArgumentError)
-      -> { BigDecimal("12345_.67E_8__9_") }.should raise_error(ArgumentError)
-    end
+    BigDecimal("12_345.67E89").should == reference
+    -> { BigDecimal("1_2_3_4_5_._6____7_E89") }.should.raise(ArgumentError)
+    -> { BigDecimal("12345_.67E_8__9_") }.should.raise(ArgumentError)
   end
 
   it "accepts NaN and [+-]Infinity" do
-    BigDecimal("NaN").nan?.should == true
+    BigDecimal("NaN").should.nan?
 
     pos_inf = BigDecimal("Infinity")
-    pos_inf.finite?.should == false
+    pos_inf.should_not.finite?
     pos_inf.should > 0
     pos_inf.should == BigDecimal("+Infinity")
 
     neg_inf = BigDecimal("-Infinity")
-    neg_inf.finite?.should == false
+    neg_inf.should_not.finite?
     neg_inf.should < 0
   end
 
+  describe "with exception: false" do
+    it "returns nil for invalid strings" do
+      BigDecimal("invalid", exception: false).should == nil
+      BigDecimal("0invalid", exception: false).should == nil
+      BigDecimal("invalid0", exception: false).should == nil
+      if BigDecimal::VERSION >= "3.1.9"
+        BigDecimal("0.", exception: false).to_i.should == 0
+      else
+        BigDecimal("0.", exception: false).should == nil
+      end
+    end
+  end
+
   describe "accepts NaN and [+-]Infinity as Float values" do
     it "works without an explicit precision" do
-      BigDecimal(Float::NAN).nan?.should == true
+      BigDecimal(Float::NAN).should.nan?
 
       pos_inf = BigDecimal(Float::INFINITY)
-      pos_inf.finite?.should == false
+      pos_inf.should_not.finite?
       pos_inf.should > 0
       pos_inf.should == BigDecimal("+Infinity")
 
       neg_inf = BigDecimal(-Float::INFINITY)
-      neg_inf.finite?.should == false
+      neg_inf.should_not.finite?
       neg_inf.should < 0
     end
 
     it "works with an explicit precision" do
-      BigDecimal(Float::NAN, Float::DIG).nan?.should == true
+      BigDecimal(Float::NAN, Float::DIG).should.nan?
 
       pos_inf = BigDecimal(Float::INFINITY, Float::DIG)
-      pos_inf.finite?.should == false
+      pos_inf.should_not.finite?
       pos_inf.should > 0
       pos_inf.should == BigDecimal("+Infinity")
 
       neg_inf = BigDecimal(-Float::INFINITY, Float::DIG)
-      neg_inf.finite?.should == false
+      neg_inf.should_not.finite?
       neg_inf.should < 0
     end
   end
@@ -150,8 +152,10 @@ describe "Kernel#BigDecimal" do
     BigDecimal("-12345.6E-1").should == -reference
   end
 
-  it "raises ArgumentError when Float is used without precision" do
-    -> { BigDecimal(1.0) }.should raise_error(ArgumentError)
+  version_is BigDecimal::VERSION, "3.3.0" do
+    it "allows Float without precision" do
+      BigDecimal(1.2).should == BigDecimal("1.2")
+    end
   end
 
   it "returns appropriate BigDecimal zero for signed zero" do
@@ -159,4 +163,77 @@ describe "Kernel#BigDecimal" do
     BigDecimal(0.0, Float::DIG).sign.should == 1
   end
 
+  it "pre-coerces long integers" do
+    BigDecimal(3).add(1 << 50, 3).should == BigDecimal('0.113e16')
+  end
+
+  it "does not call to_s when calling inspect" do
+    value = BigDecimal('44.44')
+    value.to_s.should == '0.4444e2'
+    value.inspect.should == '0.4444e2'
+
+    ruby_exe( <<-'EOF').should == "cheese 0.4444e2"
+      require 'bigdecimal'
+      module BigDecimalOverride
+        def to_s; "cheese"; end
+      end
+      BigDecimal.prepend BigDecimalOverride
+      value = BigDecimal('44.44')
+      print "#{value.to_s} #{value.inspect}"
+    EOF
+  end
+
+  describe "when interacting with Rational" do
+    before :each do
+      @a = BigDecimal('166.666666666')
+      @b = Rational(500, 3)
+      @c = @a - @b
+    end
+
+    # Check the input is as we understand it
+
+    it "has the LHS print as expected" do
+      @a.to_s.should == "0.166666666666e3"
+      @a.to_f.to_s.should == "166.666666666"
+      Float(@a).to_s.should == "166.666666666"
+    end
+
+    it "has the RHS print as expected" do
+      @b.to_s.should == "500/3"
+      @b.to_f.to_s.should == "166.66666666666666"
+      Float(@b).to_s.should == "166.66666666666666"
+    end
+
+    it "produces the expected result when done via Float" do
+      (Float(@a) - Float(@b)).to_s.should == "-6.666596163995564e-10"
+    end
+
+    it "produces the expected result when done via to_f" do
+      (@a.to_f - @b.to_f).to_s.should == "-6.666596163995564e-10"
+    end
+
+    # Check underlying methods work as we understand
+
+    it "BigDecimal(Rational, 18) produces the result we expect" do
+      BigDecimal(@b, 18).to_s.should == "0.166666666666666667e3"
+    end
+
+    # Check the top-level expression works as we expect
+
+    it "produces a BigDecimal" do
+      @c.class.should == BigDecimal
+    end
+
+    it "produces the expected result" do
+      @c.round(15).should == BigDecimal("-0.666667e-9")
+      @c.round(15).to_s.should == "-0.666667e-9"
+    end
+
+    it "produces the correct class for other arithmetic operators" do
+      (@a + @b).class.should == BigDecimal
+      (@a * @b).class.should == BigDecimal
+      (@a / @b).class.should == BigDecimal
+      (@a % @b).class.should == BigDecimal
+    end
+  end
 end
diff --git a/spec/ruby/library/bigdecimal/abs_spec.rb b/spec/ruby/library/bigdecimal/abs_spec.rb
index ddd2bae9a9..95dc45a905 100644
--- a/spec/ruby/library/bigdecimal/abs_spec.rb
+++ b/spec/ruby/library/bigdecimal/abs_spec.rb
@@ -38,7 +38,7 @@ describe "BigDecimal#abs" do
   it "properly handles special values" do
     @infinity.abs.should == @infinity
     @infinity_minus.abs.should == @infinity
-    @nan.abs.nan?.should == true # have to do it this way, since == doesn't work on NaN
+    @nan.abs.should.nan? # have to do it this way, since == doesn't work on NaN
     @zero.abs.should == 0
     @zero.abs.sign.should == BigDecimal::SIGN_POSITIVE_ZERO
     @zero_pos.abs.should == 0
diff --git a/spec/ruby/library/bigdecimal/add_spec.rb b/spec/ruby/library/bigdecimal/add_spec.rb
index 5b874687fe..a4237298f4 100644
--- a/spec/ruby/library/bigdecimal/add_spec.rb
+++ b/spec/ruby/library/bigdecimal/add_spec.rb
@@ -24,7 +24,7 @@ describe "BigDecimal#add" do
   end
 
   it "returns a + b with given precision" do
-    # documentation states, that precision ist optional, but it ain't,
+    # documentation states that precision is optional, but it ain't,
     @two.add(@one, 1).should == @three
     @one .add(@two, 1).should == @three
     @one.add(@one_minus, 1).should == @zero
@@ -60,7 +60,7 @@ describe "BigDecimal#add" do
   end
 
 #  TODO:
-#  http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/17374
+#  https://blade.ruby-lang.org/ruby-core/17374
 #
 #  This doesn't work on MRI and looks like a bug to me:
 #  one can use BigDecimal + Float, but not Bigdecimal.add(Float)
@@ -73,14 +73,6 @@ describe "BigDecimal#add" do
 #    BigDecimal("0.88").add(0.0, 1).should == BigDecimal("0.9")
 #  end
 
-  describe "with Object" do
-    it "tries to coerce the other operand to self" do
-      object = mock("Object")
-      object.should_receive(:coerce).with(@frac_3).and_return([@frac_3, @frac_4])
-      @frac_3.add(object, 1).should == BigDecimal("0.1E16")
-    end
-  end
-
   describe "with Rational" do
     it "produces a BigDecimal" do
       (@three + Rational(500, 2)).should == BigDecimal("0.253e3")
@@ -136,8 +128,8 @@ describe "BigDecimal#add" do
   end
 
   it "returns NaN if NaN is involved" do
-    @one.add(@nan, 10000).nan?.should == true
-    @nan.add(@one, 1).nan?.should == true
+    @one.add(@nan, 10000).should.nan?
+    @nan.add(@one, 1).should.nan?
   end
 
   it "returns Infinity or -Infinity if these are involved" do
@@ -166,28 +158,28 @@ describe "BigDecimal#add" do
   end
 
   it "returns NaN if Infinity + (- Infinity)" do
-    @infinity.add(@infinity_minus, 10000).nan?.should == true
-    @infinity_minus.add(@infinity, 10000).nan?.should == true
+    @infinity.add(@infinity_minus, 10000).should.nan?
+    @infinity_minus.add(@infinity, 10000).should.nan?
   end
 
   it "raises TypeError when adds nil" do
     -> {
       @one.add(nil, 10)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
     -> {
       @one.add(nil, 0)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises TypeError when precision parameter is nil" do
     -> {
       @one.add(@one, nil)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises ArgumentError when precision parameter is negative" do
     -> {
       @one.add(@one, -10)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/ceil_spec.rb b/spec/ruby/library/bigdecimal/ceil_spec.rb
index 60e71b12fb..3d94b8e578 100644
--- a/spec/ruby/library/bigdecimal/ceil_spec.rb
+++ b/spec/ruby/library/bigdecimal/ceil_spec.rb
@@ -48,9 +48,9 @@ describe "BigDecimal#ceil" do
   end
 
   it "raise exception, if self is special value" do
-    -> { @infinity.ceil }.should raise_error(FloatDomainError)
-    -> { @infinity_neg.ceil }.should raise_error(FloatDomainError)
-    -> { @nan.ceil }.should raise_error(FloatDomainError)
+    -> { @infinity.ceil }.should.raise(FloatDomainError)
+    -> { @infinity_neg.ceil }.should.raise(FloatDomainError)
+    -> { @nan.ceil }.should.raise(FloatDomainError)
   end
 
   it "returns n digits right of the decimal point if given n > 0" do
diff --git a/spec/ruby/library/bigdecimal/comparison_spec.rb b/spec/ruby/library/bigdecimal/comparison_spec.rb
index a1e09b601f..c53187b727 100644
--- a/spec/ruby/library/bigdecimal/comparison_spec.rb
+++ b/spec/ruby/library/bigdecimal/comparison_spec.rb
@@ -18,7 +18,7 @@ describe "BigDecimal#<=>" do
       def coerce(other)
         return [other, BigDecimal('123')]
       end
-      def >= (other)
+      def >=(other)
         BigDecimal('123') >= other
       end
     end
diff --git a/spec/ruby/library/bigdecimal/constants_spec.rb b/spec/ruby/library/bigdecimal/constants_spec.rb
index 1eb24d85cb..f2cc42dfc9 100644
--- a/spec/ruby/library/bigdecimal/constants_spec.rb
+++ b/spec/ruby/library/bigdecimal/constants_spec.rb
@@ -2,20 +2,18 @@ require_relative '../../spec_helper'
 require 'bigdecimal'
 
 describe "BigDecimal constants" do
-  ruby_version_is "2.5" do
-    it "defines a VERSION value" do
-      BigDecimal.const_defined?(:VERSION).should be_true
-    end
+  it "defines a VERSION value" do
+    BigDecimal.const_defined?(:VERSION).should == true
   end
 
   it "has a BASE value" do
     # The actual one is decided based on HAVE_INT64_T in MRI,
     # which is hard to check here.
-    [10000, 1000000000].should include(BigDecimal::BASE)
+    [10000, 1000000000].should.include?(BigDecimal::BASE)
   end
 
   it "has a NaN value" do
-    BigDecimal::NAN.nan?.should be_true
+    BigDecimal::NAN.nan?.should == true
   end
 
   it "has an INFINITY value" do
diff --git a/spec/ruby/library/bigdecimal/core_spec.rb b/spec/ruby/library/bigdecimal/core_spec.rb
new file mode 100644
index 0000000000..8f64fdf388
--- /dev/null
+++ b/spec/ruby/library/bigdecimal/core_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../spec_helper'
+require 'bigdecimal'
+
+describe "Core extension by bigdecimal" do
+  context "Integer#coerce" do
+    it "produces Floats" do
+      x, y = 3.coerce(BigDecimal("3.4"))
+      x.class.should == Float
+      x.should == 3.4
+      y.class.should == Float
+      y.should == 3.0
+    end
+  end
+
+  describe "Time.at passed BigDecimal" do
+    it "doesn't round input value" do
+      Time.at(BigDecimal('1.1')).to_f.should == 1.1
+    end
+  end
+
+  describe "BigDecimal#log" do
+    it "handles high-precision Rational arguments" do
+      # log(BigDecimal(r, 50), 50)
+      result1 = BigDecimal('0.22314354220170971436137296411949880462556361100856e0')
+      # log(BigDecimal(r, 1000), 50)
+      result2 = BigDecimal('0.22314354220170971436137296411949880462556361100853e0')
+      r = Rational(1_234_567_890, 987_654_321)
+      [result1, result2].should.include?(BigMath.log(r, 50).mult(1, 50))
+    end
+  end
+
+  describe "Rational#coerce" do
+    it "returns the passed argument, self as Float, when given a Float" do
+      result = Rational(3, 4).coerce(1.0)
+      result.should == [1.0, 0.75]
+      result.first.is_a?(Float).should == true
+      result.last.is_a?(Float).should == true
+    end
+
+    it "returns the passed argument, self as Rational, when given an Integer" do
+      result = Rational(3, 4).coerce(10)
+      result.should == [Rational(10, 1), Rational(3, 4)]
+      result.first.is_a?(Rational).should == true
+      result.last.is_a?(Rational).should == true
+    end
+
+    it "coerces to Rational, when given a Complex" do
+      Rational(3, 4).coerce(Complex(5)).should == [Rational(5, 1), Rational(3, 4)]
+      Rational(12, 4).coerce(Complex(5, 1)).should == [Complex(5, 1), Complex(3)]
+    end
+
+    it "returns [argument, self] when given a Rational" do
+      Rational(3, 7).coerce(Rational(9, 2)).should == [Rational(9, 2), Rational(3, 7)]
+    end
+
+    it "raises an error when passed a BigDecimal" do
+      -> {
+        Rational(500, 3).coerce(BigDecimal('166.666666666'))
+      }.should.raise(TypeError, /BigDecimal can't be coerced into Rational/)
+    end
+  end
+end
diff --git a/spec/ruby/library/bigdecimal/div_spec.rb b/spec/ruby/library/bigdecimal/div_spec.rb
index 0c9eb2ddec..967d8b5221 100644
--- a/spec/ruby/library/bigdecimal/div_spec.rb
+++ b/spec/ruby/library/bigdecimal/div_spec.rb
@@ -51,9 +51,9 @@ describe "BigDecimal#div" do
   end
 
   it "raises FloatDomainError if NaN is involved" do
-    -> { @one.div(@nan) }.should raise_error(FloatDomainError)
-    -> { @nan.div(@one) }.should raise_error(FloatDomainError)
-    -> { @nan.div(@nan) }.should raise_error(FloatDomainError)
+    -> { @one.div(@nan) }.should.raise(FloatDomainError)
+    -> { @nan.div(@one) }.should.raise(FloatDomainError)
+    -> { @nan.div(@nan) }.should.raise(FloatDomainError)
   end
 
   it "returns 0 if divided by Infinity and no precision given" do
@@ -69,30 +69,30 @@ describe "BigDecimal#div" do
   end
 
   it "raises ZeroDivisionError if divided by zero and no precision given" do
-    -> { @one.div(@zero) }.should raise_error(ZeroDivisionError)
-    -> { @one.div(@zero_plus) }.should raise_error(ZeroDivisionError)
-    -> { @one.div(@zero_minus) }.should raise_error(ZeroDivisionError)
-
-    -> { @zero.div(@zero) }.should raise_error(ZeroDivisionError)
-    -> { @zero_minus.div(@zero_plus) }.should raise_error(ZeroDivisionError)
-    -> { @zero_minus.div(@zero_minus) }.should raise_error(ZeroDivisionError)
-    -> { @zero_plus.div(@zero_minus) }.should raise_error(ZeroDivisionError)
+    -> { @one.div(@zero) }.should.raise(ZeroDivisionError)
+    -> { @one.div(@zero_plus) }.should.raise(ZeroDivisionError)
+    -> { @one.div(@zero_minus) }.should.raise(ZeroDivisionError)
+
+    -> { @zero.div(@zero) }.should.raise(ZeroDivisionError)
+    -> { @zero_minus.div(@zero_plus) }.should.raise(ZeroDivisionError)
+    -> { @zero_minus.div(@zero_minus) }.should.raise(ZeroDivisionError)
+    -> { @zero_plus.div(@zero_minus) }.should.raise(ZeroDivisionError)
   end
 
   it "returns NaN if zero is divided by zero" do
-    @zero.div(@zero, 0).nan?.should == true
-    @zero_minus.div(@zero_plus, 0).nan?.should == true
-    @zero_plus.div(@zero_minus, 0).nan?.should == true
+    @zero.div(@zero, 0).should.nan?
+    @zero_minus.div(@zero_plus, 0).should.nan?
+    @zero_plus.div(@zero_minus, 0).should.nan?
 
-    @zero.div(@zero, 10).nan?.should == true
-    @zero_minus.div(@zero_plus, 10).nan?.should == true
-    @zero_plus.div(@zero_minus, 10).nan?.should == true
+    @zero.div(@zero, 10).should.nan?
+    @zero_minus.div(@zero_plus, 10).should.nan?
+    @zero_plus.div(@zero_minus, 10).should.nan?
   end
 
   it "raises FloatDomainError if (+|-) Infinity divided by 1 and no precision given" do
-    -> { @infinity_minus.div(@one) }.should raise_error(FloatDomainError)
-    -> { @infinity.div(@one) }.should raise_error(FloatDomainError)
-    -> { @infinity_minus.div(@one_minus) }.should raise_error(FloatDomainError)
+    -> { @infinity_minus.div(@one) }.should.raise(FloatDomainError)
+    -> { @infinity.div(@one) }.should.raise(FloatDomainError)
+    -> { @infinity_minus.div(@one_minus) }.should.raise(FloatDomainError)
   end
 
   it "returns (+|-)Infinity if (+|-)Infinity by 1 and precision given" do
@@ -102,8 +102,8 @@ describe "BigDecimal#div" do
   end
 
   it "returns NaN if Infinity / ((+|-) Infinity)" do
-    @infinity.div(@infinity_minus, 100000).nan?.should == true
-    @infinity_minus.div(@infinity, 1).nan?.should == true
+    @infinity.div(@infinity_minus, 100000).should.nan?
+    @infinity_minus.div(@infinity, 1).should.nan?
   end
 
 
diff --git a/spec/ruby/library/bigdecimal/divmod_spec.rb b/spec/ruby/library/bigdecimal/divmod_spec.rb
index ae8b84983a..d170c6f845 100644
--- a/spec/ruby/library/bigdecimal/divmod_spec.rb
+++ b/spec/ruby/library/bigdecimal/divmod_spec.rb
@@ -5,8 +5,8 @@ require 'bigdecimal'
 module DivmodSpecs
   def self.check_both_nan(array)
     array.length.should == 2
-    array[0].nan?.should == true
-    array[1].nan?.should == true
+    array[0].should.nan?
+    array[1].should.nan?
   end
   def self.check_both_bigdecimal(array)
     array.length.should == 2
@@ -33,14 +33,16 @@ describe "BigDecimal#mod_part_of_divmod" do
     end
   end
 
-  it_behaves_like :bigdecimal_modulo, :mod_part_of_divmod
+  version_is BigDecimal::VERSION, ""..."4.0.0" do
+    it_behaves_like :bigdecimal_modulo, :mod_part_of_divmod
+  end
 
   it "raises ZeroDivisionError if other is zero" do
     bd5667 = BigDecimal("5667.19")
-
-    -> { bd5667.mod_part_of_divmod(0) }.should raise_error(ZeroDivisionError)
-    -> { bd5667.mod_part_of_divmod(BigDecimal("0")) }.should raise_error(ZeroDivisionError)
-    -> { @zero.mod_part_of_divmod(@zero) }.should raise_error(ZeroDivisionError)
+    zero = BigDecimal("0")
+    -> { bd5667.mod_part_of_divmod(0) }.should.raise(ZeroDivisionError)
+    -> { bd5667.mod_part_of_divmod(BigDecimal("0")) }.should.raise(ZeroDivisionError)
+    -> { zero.mod_part_of_divmod(zero) }.should.raise(ZeroDivisionError)
   end
 end
 
@@ -73,14 +75,25 @@ describe "BigDecimal#divmod" do
     @zeroes = [@zero, @zero_pos, @zero_neg]
   end
 
-  it "divides value, returns an array" do
-    res = @a.divmod(5)
-    res.kind_of?(Array).should == true
+  version_is BigDecimal::VERSION, ""..."4.0.0" do
+    it "divides value, returns [BigDecimal, BigDecimal]" do
+      res = @a.divmod(5)
+      res.kind_of?(Array).should == true
+      DivmodSpecs.check_both_bigdecimal(res)
+    end
+  end
+
+  version_is BigDecimal::VERSION, "4.0.0" do
+    it "divides value, returns [Integer, BigDecimal]" do
+      res = @a.divmod(5)
+      res.kind_of?(Array).should == true
+      res[0].kind_of?(Integer).should == true
+      res[1].kind_of?(BigDecimal).should == true
+    end
   end
 
   it "array contains quotient and modulus as BigDecimal" do
     res = @a.divmod(5)
-    DivmodSpecs.check_both_bigdecimal(res)
     res[0].should == BigDecimal('0.8E1')
     res[1].should == BigDecimal('2.00000000000000000001')
 
@@ -123,43 +136,62 @@ describe "BigDecimal#divmod" do
     values_and_zeroes.each do |val1|
       values.each do |val2|
         res = val1.divmod(val2)
-        DivmodSpecs.check_both_bigdecimal(res)
         res[0].should == ((val1/val2).floor)
         res[1].should == (val1 - res[0] * val2)
       end
     end
   end
 
-  it "returns an array of two NaNs if NaN is involved" do
-    (@special_vals + @regular_vals + @zeroes).each do |val|
-      DivmodSpecs.check_both_nan(val.divmod(@nan))
-      DivmodSpecs.check_both_nan(@nan.divmod(val))
+  version_is BigDecimal::VERSION, "4.0.0" do
+    it "raise FloatDomainError error if NaN is involved" do
+      (@special_vals + @regular_vals + @zeroes).each do |val|
+        -> { val.divmod(@nan) }.should.raise(FloatDomainError)
+        -> { @nan.divmod(val) }.should.raise(FloatDomainError)
+      end
+    end
+  end
+
+  version_is BigDecimal::VERSION, ""..."4.0.0" do
+    it "returns an array of two NaNs if NaN is involved" do
+      (@special_vals + @regular_vals + @zeroes).each do |val|
+        DivmodSpecs.check_both_nan(val.divmod(@nan))
+        DivmodSpecs.check_both_nan(@nan.divmod(val))
+      end
     end
   end
 
   it "raises ZeroDivisionError if the divisor is zero" do
     (@special_vals + @regular_vals + @zeroes - [@nan]).each do |val|
       @zeroes.each do |zero|
-        -> { val.divmod(zero) }.should raise_error(ZeroDivisionError)
+        -> { val.divmod(zero) }.should.raise(ZeroDivisionError)
       end
     end
   end
 
-  it "returns an array of Infinity and NaN if the dividend is Infinity" do
-    @regular_vals.each do |val|
-      array = @infinity.divmod(val)
-      array.length.should == 2
-      array[0].infinite?.should == (val > 0 ? 1 : -1)
-      array[1].nan?.should == true
+  version_is BigDecimal::VERSION, ""..."4.0.0" do
+    it "returns an array of Infinity and NaN if the dividend is Infinity" do
+      @regular_vals.each do |val|
+        array = @infinity.divmod(val)
+        array.length.should == 2
+        array[0].infinite?.should == (val > 0 ? 1 : -1)
+        array[1].should.nan?
+      end
     end
   end
 
-  it "returns an array of zero and the dividend if the divisor is Infinity" do
-    @regular_vals.each do |val|
-      array = val.divmod(@infinity)
-      array.length.should == 2
-      array[0].should == @zero
-      array[1].should == val
+  version_is BigDecimal::VERSION, "3.3.0" do
+    it "returns an array of zero and the dividend or minus one and Infinity if the divisor is Infinity" do
+      @regular_vals.each do |val|
+        array = val.divmod(@infinity)
+        array.length.should == 2
+        if val >= 0
+          array[0].should == @zero
+          array[1].should == val
+        else
+          array[0].should == @one_minus
+          array[1].should == @infinity
+        end
+      end
     end
   end
 
@@ -174,7 +206,7 @@ describe "BigDecimal#divmod" do
   it "raises TypeError if the argument cannot be coerced to BigDecimal" do
     -> {
       @one.divmod('1')
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/exponent_spec.rb b/spec/ruby/library/bigdecimal/exponent_spec.rb
index a349ac093f..8877147955 100644
--- a/spec/ruby/library/bigdecimal/exponent_spec.rb
+++ b/spec/ruby/library/bigdecimal/exponent_spec.rb
@@ -18,17 +18,6 @@ describe "BigDecimal#exponent" do
     BigDecimal("1234567E10").exponent.should == 17
   end
 
-# commenting this spec out after discussion with Defiler, since it seems to be an MRI bug, not a real feature
-=begin
-  platform_is wordsize: 32 do
-    # TODO: write specs for both 32 and 64 bit
-    it "returns 0 if exponent can't be represented as Fixnum" do
-      BigDecimal("2E1000000000000000").exponent.should == 0
-      BigDecimal("-5E-999999999999999").exponent.should == 0
-    end
-  end
-=end
-
   it "returns 0 if self is 0" do
     BigDecimal("0").exponent.should == 0
     BigDecimal("+0").exponent.should == 0
diff --git a/spec/ruby/library/bigdecimal/finite_spec.rb b/spec/ruby/library/bigdecimal/finite_spec.rb
index 6685d589b6..8fc06029bb 100644
--- a/spec/ruby/library/bigdecimal/finite_spec.rb
+++ b/spec/ruby/library/bigdecimal/finite_spec.rb
@@ -21,14 +21,14 @@ describe "BigDecimal#finite?" do
   end
 
   it "is false if Infinity or NaN" do
-    @infinity.finite?.should == false
-    @infinity_minus.finite?.should == false
-    @nan.finite?.should == false
+    @infinity.should_not.finite?
+    @infinity_minus.should_not.finite?
+    @nan.should_not.finite?
   end
 
   it "returns true for finite values" do
     @finite_vals.each do |val|
-      val.finite?.should == true
+      val.should.finite?
     end
   end
 end
diff --git a/spec/ruby/library/bigdecimal/fix_spec.rb b/spec/ruby/library/bigdecimal/fix_spec.rb
index 53b30cbf8b..dceb2ce867 100644
--- a/spec/ruby/library/bigdecimal/fix_spec.rb
+++ b/spec/ruby/library/bigdecimal/fix_spec.rb
@@ -2,20 +2,20 @@ require_relative '../../spec_helper'
 require 'bigdecimal'
 
 describe "BigDecimal#fix" do
-    before :each do
-      @zero = BigDecimal("0")
-      @mixed = BigDecimal("1.23456789")
-      @pos_int = BigDecimal("2E5555")
-      @neg_int = BigDecimal("-2E5555")
-      @pos_frac = BigDecimal("2E-9999")
-      @neg_frac = BigDecimal("-2E-9999")
-
-      @infinity = BigDecimal("Infinity")
-      @infinity_neg = BigDecimal("-Infinity")
-      @nan = BigDecimal("NaN")
-      @zero_pos = BigDecimal("+0")
-      @zero_neg = BigDecimal("-0")
-    end
+  before :each do
+    @zero = BigDecimal("0")
+    @mixed = BigDecimal("1.23456789")
+    @pos_int = BigDecimal("2E5555")
+    @neg_int = BigDecimal("-2E5555")
+    @pos_frac = BigDecimal("2E-9999")
+    @neg_frac = BigDecimal("-2E-9999")
+
+    @infinity = BigDecimal("Infinity")
+    @infinity_neg = BigDecimal("-Infinity")
+    @nan = BigDecimal("NaN")
+    @zero_pos = BigDecimal("+0")
+    @zero_neg = BigDecimal("-0")
+  end
 
   it "returns a BigDecimal" do
     BigDecimal("2E100000000").fix.kind_of?(BigDecimal).should == true
@@ -34,7 +34,7 @@ describe "BigDecimal#fix" do
   it "correctly handles special values" do
     @infinity.fix.should == @infinity
     @infinity_neg.fix.should == @infinity_neg
-    @nan.fix.nan?.should == true
+    @nan.fix.should.nan?
   end
 
   it "returns 0 if the absolute value is < 1" do
@@ -51,7 +51,7 @@ describe "BigDecimal#fix" do
   it "does not allow any arguments" do
     -> {
       @mixed.fix(10)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/floor_spec.rb b/spec/ruby/library/bigdecimal/floor_spec.rb
index a7dfec2c9a..c0666c668c 100644
--- a/spec/ruby/library/bigdecimal/floor_spec.rb
+++ b/spec/ruby/library/bigdecimal/floor_spec.rb
@@ -41,9 +41,9 @@ describe "BigDecimal#floor" do
   end
 
   it "raise exception, if self is special value" do
-    -> { @infinity.floor }.should raise_error(FloatDomainError)
-    -> { @infinity_neg.floor }.should raise_error(FloatDomainError)
-    -> { @nan.floor }.should raise_error(FloatDomainError)
+    -> { @infinity.floor }.should.raise(FloatDomainError)
+    -> { @infinity_neg.floor }.should.raise(FloatDomainError)
+    -> { @nan.floor }.should.raise(FloatDomainError)
   end
 
   it "returns n digits right of the decimal point if given n > 0" do
diff --git a/spec/ruby/library/bigdecimal/frac_spec.rb b/spec/ruby/library/bigdecimal/frac_spec.rb
index 4a023b4ff6..11ccf03c2f 100644
--- a/spec/ruby/library/bigdecimal/frac_spec.rb
+++ b/spec/ruby/library/bigdecimal/frac_spec.rb
@@ -42,7 +42,7 @@ describe "BigDecimal#frac" do
   it "correctly handles special values" do
     @infinity.frac.should == @infinity
     @infinity_neg.frac.should == @infinity_neg
-    @nan.frac.nan?.should == true
+    @nan.frac.should.nan?
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/gt_spec.rb b/spec/ruby/library/bigdecimal/gt_spec.rb
index 4717cfdd9d..e9c9a60e75 100644
--- a/spec/ruby/library/bigdecimal/gt_spec.rb
+++ b/spec/ruby/library/bigdecimal/gt_spec.rb
@@ -17,7 +17,7 @@ describe "BigDecimal#>" do
       def coerce(other)
         return [other, BigDecimal('123')]
       end
-      def > (other)
+      def >(other)
         BigDecimal('123') > other
       end
     end
@@ -86,11 +86,11 @@ describe "BigDecimal#>" do
   end
 
   it "raises an ArgumentError if the argument can't be coerced into a BigDecimal" do
-    -> {@zero         > nil }.should raise_error(ArgumentError)
-    -> {@infinity     > nil }.should raise_error(ArgumentError)
-    -> {@infinity_neg > nil }.should raise_error(ArgumentError)
-    -> {@mixed        > nil }.should raise_error(ArgumentError)
-    -> {@pos_int      > nil }.should raise_error(ArgumentError)
-    -> {@neg_frac     > nil }.should raise_error(ArgumentError)
+    -> {@zero         > nil }.should.raise(ArgumentError)
+    -> {@infinity     > nil }.should.raise(ArgumentError)
+    -> {@infinity_neg > nil }.should.raise(ArgumentError)
+    -> {@mixed        > nil }.should.raise(ArgumentError)
+    -> {@pos_int      > nil }.should.raise(ArgumentError)
+    -> {@neg_frac     > nil }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/gte_spec.rb b/spec/ruby/library/bigdecimal/gte_spec.rb
index 8dc81707f0..548f3efe4c 100644
--- a/spec/ruby/library/bigdecimal/gte_spec.rb
+++ b/spec/ruby/library/bigdecimal/gte_spec.rb
@@ -17,7 +17,7 @@ describe "BigDecimal#>=" do
       def coerce(other)
         return [other, BigDecimal('123')]
       end
-      def >= (other)
+      def >=(other)
         BigDecimal('123') >= other
       end
     end
@@ -90,11 +90,11 @@ describe "BigDecimal#>=" do
   end
 
   it "returns nil if the argument is nil" do
-    -> {@zero         >= nil }.should raise_error(ArgumentError)
-    -> {@infinity     >= nil }.should raise_error(ArgumentError)
-    -> {@infinity_neg >= nil }.should raise_error(ArgumentError)
-    -> {@mixed        >= nil }.should raise_error(ArgumentError)
-    -> {@pos_int      >= nil }.should raise_error(ArgumentError)
-    -> {@neg_frac     >= nil }.should raise_error(ArgumentError)
+    -> {@zero         >= nil }.should.raise(ArgumentError)
+    -> {@infinity     >= nil }.should.raise(ArgumentError)
+    -> {@infinity_neg >= nil }.should.raise(ArgumentError)
+    -> {@mixed        >= nil }.should.raise(ArgumentError)
+    -> {@pos_int      >= nil }.should.raise(ArgumentError)
+    -> {@neg_frac     >= nil }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/lt_spec.rb b/spec/ruby/library/bigdecimal/lt_spec.rb
index 61f4f19912..c3f3573247 100644
--- a/spec/ruby/library/bigdecimal/lt_spec.rb
+++ b/spec/ruby/library/bigdecimal/lt_spec.rb
@@ -17,7 +17,7 @@ describe "BigDecimal#<" do
       def coerce(other)
         return [other, BigDecimal('123')]
       end
-      def < (other)
+      def <(other)
         BigDecimal('123') < other
       end
     end
@@ -84,11 +84,11 @@ describe "BigDecimal#<" do
   end
 
   it "raises an ArgumentError if the argument can't be coerced into a BigDecimal" do
-    -> {@zero         < nil }.should raise_error(ArgumentError)
-    -> {@infinity     < nil }.should raise_error(ArgumentError)
-    -> {@infinity_neg < nil }.should raise_error(ArgumentError)
-    -> {@mixed        < nil }.should raise_error(ArgumentError)
-    -> {@pos_int      < nil }.should raise_error(ArgumentError)
-    -> {@neg_frac     < nil }.should raise_error(ArgumentError)
+    -> {@zero         < nil }.should.raise(ArgumentError)
+    -> {@infinity     < nil }.should.raise(ArgumentError)
+    -> {@infinity_neg < nil }.should.raise(ArgumentError)
+    -> {@mixed        < nil }.should.raise(ArgumentError)
+    -> {@pos_int      < nil }.should.raise(ArgumentError)
+    -> {@neg_frac     < nil }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/lte_spec.rb b/spec/ruby/library/bigdecimal/lte_spec.rb
index fc632315f8..7918bde88b 100644
--- a/spec/ruby/library/bigdecimal/lte_spec.rb
+++ b/spec/ruby/library/bigdecimal/lte_spec.rb
@@ -17,7 +17,7 @@ describe "BigDecimal#<=" do
       def coerce(other)
         return [other, BigDecimal('123')]
       end
-      def <= (other)
+      def <=(other)
         BigDecimal('123') <= other
       end
     end
@@ -90,11 +90,11 @@ describe "BigDecimal#<=" do
   end
 
   it "raises an ArgumentError if the argument can't be coerced into a BigDecimal" do
-    -> {@zero         <= nil }.should raise_error(ArgumentError)
-    -> {@infinity     <= nil }.should raise_error(ArgumentError)
-    -> {@infinity_neg <= nil }.should raise_error(ArgumentError)
-    -> {@mixed        <= nil }.should raise_error(ArgumentError)
-    -> {@pos_int      <= nil }.should raise_error(ArgumentError)
-    -> {@neg_frac     <= nil }.should raise_error(ArgumentError)
+    -> {@zero         <= nil }.should.raise(ArgumentError)
+    -> {@infinity     <= nil }.should.raise(ArgumentError)
+    -> {@infinity_neg <= nil }.should.raise(ArgumentError)
+    -> {@mixed        <= nil }.should.raise(ArgumentError)
+    -> {@pos_int      <= nil }.should.raise(ArgumentError)
+    -> {@neg_frac     <= nil }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/minus_spec.rb b/spec/ruby/library/bigdecimal/minus_spec.rb
index 267a0f7eab..bd3c19584b 100644
--- a/spec/ruby/library/bigdecimal/minus_spec.rb
+++ b/spec/ruby/library/bigdecimal/minus_spec.rb
@@ -26,18 +26,18 @@ describe "BigDecimal#-" do
   end
 
   it "returns NaN if NaN is involved" do
-    (@one - @nan).nan?.should == true
-    (@nan - @one).nan?.should == true
-    (@nan - @nan).nan?.should == true
-    (@nan - @infinity).nan?.should == true
-    (@nan - @infinity_minus).nan?.should == true
-    (@infinity - @nan).nan?.should == true
-    (@infinity_minus - @nan).nan?.should == true
+    (@one - @nan).should.nan?
+    (@nan - @one).should.nan?
+    (@nan - @nan).should.nan?
+    (@nan - @infinity).should.nan?
+    (@nan - @infinity_minus).should.nan?
+    (@infinity - @nan).should.nan?
+    (@infinity_minus - @nan).should.nan?
   end
 
   it "returns NaN both operands are infinite with the same sign" do
-    (@infinity - @infinity).nan?.should == true
-    (@infinity_minus - @infinity_minus).nan?.should == true
+    (@infinity - @infinity).should.nan?
+    (@infinity_minus - @infinity_minus).should.nan?
   end
 
   it "returns Infinity or -Infinity if these are involved" do
diff --git a/spec/ruby/library/bigdecimal/mode_spec.rb b/spec/ruby/library/bigdecimal/mode_spec.rb
index f57028ae5d..26e6d0ea75 100644
--- a/spec/ruby/library/bigdecimal/mode_spec.rb
+++ b/spec/ruby/library/bigdecimal/mode_spec.rb
@@ -12,7 +12,7 @@ describe "BigDecimal.mode" do
   end
 
   it "returns the appropriate value and continue the computation if the flag is false" do
-    BigDecimal("NaN").add(BigDecimal("1"),0).nan?.should == true
+    BigDecimal("NaN").add(BigDecimal("1"),0).should.nan?
     BigDecimal("0").add(BigDecimal("Infinity"),0).should == BigDecimal("Infinity")
     BigDecimal("1").quo(BigDecimal("0")).should == BigDecimal("Infinity")
   end
@@ -24,13 +24,13 @@ describe "BigDecimal.mode" do
 
   it "raise an exception if the flag is true" do
     BigDecimal.mode(BigDecimal::EXCEPTION_NaN, true)
-    -> { BigDecimal("NaN").add(BigDecimal("1"),0) }.should raise_error(FloatDomainError)
+    -> { BigDecimal("NaN").add(BigDecimal("1"),0) }.should.raise(FloatDomainError)
     BigDecimal.mode(BigDecimal::EXCEPTION_INFINITY, true)
-    -> { BigDecimal("0").add(BigDecimal("Infinity"),0) }.should raise_error(FloatDomainError)
+    -> { BigDecimal("0").add(BigDecimal("Infinity"),0) }.should.raise(FloatDomainError)
     BigDecimal.mode(BigDecimal::EXCEPTION_ZERODIVIDE, true)
-    -> { BigDecimal("1").quo(BigDecimal("0")) }.should raise_error(FloatDomainError)
+    -> { BigDecimal("1").quo(BigDecimal("0")) }.should.raise(FloatDomainError)
     BigDecimal.mode(BigDecimal::EXCEPTION_OVERFLOW, true)
-    -> { BigDecimal("1E11111111111111111111") }.should raise_error(FloatDomainError)
-    -> { (BigDecimal("1E1000000000000000000")**10) }.should raise_error(FloatDomainError)
+    -> { BigDecimal("1E11111111111111111111") }.should.raise(FloatDomainError)
+    -> { (BigDecimal("1E1000000000000000000")**10) }.should.raise(FloatDomainError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/mult_spec.rb b/spec/ruby/library/bigdecimal/mult_spec.rb
index b7f8044b0b..2353df9cb8 100644
--- a/spec/ruby/library/bigdecimal/mult_spec.rb
+++ b/spec/ruby/library/bigdecimal/mult_spec.rb
@@ -21,12 +21,4 @@ describe "BigDecimal#mult" do
     @e.mult(@one, 1).should be_close(@one, @tolerance)
     @e3_minus.mult(@one, 1).should be_close(0, @tolerance2)
   end
-
-  describe "with Object" do
-    it "tries to coerce the other operand to self" do
-      object = mock("Object")
-      object.should_receive(:coerce).with(@e3_minus).and_return([@e3_minus, @e3_plus])
-      @e3_minus.mult(object, 1).should == BigDecimal("9")
-    end
-  end
 end
diff --git a/spec/ruby/library/bigdecimal/nan_spec.rb b/spec/ruby/library/bigdecimal/nan_spec.rb
index 705492614b..9eaf69b610 100644
--- a/spec/ruby/library/bigdecimal/nan_spec.rb
+++ b/spec/ruby/library/bigdecimal/nan_spec.rb
@@ -4,20 +4,20 @@ require 'bigdecimal'
 describe "BigDecimal#nan?" do
 
   it "returns true if self is not a number" do
-    BigDecimal("NaN").nan?.should == true
+    BigDecimal("NaN").should.nan?
   end
 
   it "returns false if self is not a NaN" do
-    BigDecimal("Infinity").nan?.should == false
-    BigDecimal("-Infinity").nan?.should == false
-    BigDecimal("0").nan?.should == false
-    BigDecimal("+0").nan?.should == false
-    BigDecimal("-0").nan?.should == false
-    BigDecimal("2E40001").nan?.should == false
-    BigDecimal("3E-20001").nan?.should == false
-    BigDecimal("0E-200000000").nan?.should == false
-    BigDecimal("0E200000000000").nan?.should == false
-    BigDecimal("0.000000000000000000000000").nan?.should == false
+    BigDecimal("Infinity").should_not.nan?
+    BigDecimal("-Infinity").should_not.nan?
+    BigDecimal("0").should_not.nan?
+    BigDecimal("+0").should_not.nan?
+    BigDecimal("-0").should_not.nan?
+    BigDecimal("2E40001").should_not.nan?
+    BigDecimal("3E-20001").should_not.nan?
+    BigDecimal("0E-200000000").should_not.nan?
+    BigDecimal("0E200000000000").should_not.nan?
+    BigDecimal("0.000000000000000000000000").should_not.nan?
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/nonzero_spec.rb b/spec/ruby/library/bigdecimal/nonzero_spec.rb
index f43c4393cd..31421ebdf4 100644
--- a/spec/ruby/library/bigdecimal/nonzero_spec.rb
+++ b/spec/ruby/library/bigdecimal/nonzero_spec.rb
@@ -10,11 +10,11 @@ describe "BigDecimal#nonzero?" do
     infinity = BigDecimal("Infinity")
     infinity_minus = BigDecimal("-Infinity")
     nan = BigDecimal("NaN")
-    infinity.nonzero?.should equal(infinity)
-    infinity_minus.nonzero?.should equal(infinity_minus)
-    nan.nonzero?.should equal(nan)
-    e3_minus.nonzero?.should equal(e3_minus)
-    e2_plus.nonzero?.should equal(e2_plus)
+    infinity.nonzero?.should.equal?(infinity)
+    infinity_minus.nonzero?.should.equal?(infinity_minus)
+    nan.nonzero?.should.equal?(nan)
+    e3_minus.nonzero?.should.equal?(e3_minus)
+    e2_plus.nonzero?.should.equal?(e2_plus)
   end
 
   it "returns nil otherwise" do
diff --git a/spec/ruby/library/bigdecimal/plus_spec.rb b/spec/ruby/library/bigdecimal/plus_spec.rb
index cefc43aeaa..d1934841c8 100644
--- a/spec/ruby/library/bigdecimal/plus_spec.rb
+++ b/spec/ruby/library/bigdecimal/plus_spec.rb
@@ -30,8 +30,8 @@ describe "BigDecimal#+" do
   end
 
   it "returns NaN if NaN is involved" do
-    (@one + @nan).nan?.should == true
-    (@nan + @one).nan?.should == true
+    (@one + @nan).should.nan?
+    (@nan + @one).should.nan?
   end
 
   it "returns Infinity or -Infinity if these are involved" do
@@ -41,7 +41,7 @@ describe "BigDecimal#+" do
   end
 
   it "returns NaN if Infinity + (- Infinity)" do
-    (@infinity + @infinity_minus).nan?.should == true
+    (@infinity + @infinity_minus).should.nan?
   end
 
   describe "with Object" do
diff --git a/spec/ruby/library/bigdecimal/precs_spec.rb b/spec/ruby/library/bigdecimal/precs_spec.rb
deleted file mode 100644
index f9320f2b9e..0000000000
--- a/spec/ruby/library/bigdecimal/precs_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../spec_helper'
-require 'bigdecimal'
-
-describe "BigDecimal#precs" do
-
-  before :each do
-    @infinity = BigDecimal("Infinity")
-    @infinity_neg = BigDecimal("-Infinity")
-    @nan = BigDecimal("NaN")
-    @zero = BigDecimal("0")
-    @zero_neg = BigDecimal("-0")
-
-    @arr = [BigDecimal("2E40001"), BigDecimal("3E-20001"),\
-            @infinity, @infinity_neg, @nan, @zero, @zero_neg]
-    @precision = BigDecimal::BASE.to_s.length - 1
-  end
-
-  it "returns array of two values" do
-    @arr.each do |x|
-      x.precs.kind_of?(Array).should == true
-      x.precs.size.should == 2
-    end
-  end
-
-  it "returns Integers as array values" do
-    @arr.each do |x|
-      x.precs[0].kind_of?(Integer).should == true
-      x.precs[1].kind_of?(Integer).should == true
-    end
-  end
-
-  it "returns the current value of significant digits as the first value" do
-    BigDecimal("3.14159").precs[0].should >= 6
-    BigDecimal('1').precs[0].should == BigDecimal('1' + '0' * 100).precs[0]
-    [@infinity, @infinity_neg, @nan, @zero, @zero_neg].each do |value|
-      value.precs[0].should <= @precision
-    end
-  end
-
-  it "returns the maximum number of significant digits as the second value" do
-    BigDecimal("3.14159").precs[1].should >= 6
-    BigDecimal('1').precs[1].should >= 1
-    BigDecimal('1' + '0' * 100).precs[1] >= 101
-    [@infinity, @infinity_neg, @nan, @zero, @zero_neg].each do |value|
-      value.precs[1].should >= 1
-    end
-  end
-end
diff --git a/spec/ruby/library/bigdecimal/quo_spec.rb b/spec/ruby/library/bigdecimal/quo_spec.rb
index a5c5651778..65a4330303 100644
--- a/spec/ruby/library/bigdecimal/quo_spec.rb
+++ b/spec/ruby/library/bigdecimal/quo_spec.rb
@@ -6,7 +6,7 @@ describe "BigDecimal#quo" do
   it_behaves_like :bigdecimal_quo, :quo, []
 
   it "returns NaN if NaN is involved" do
-    BigDecimal("1").quo(BigDecimal("NaN")).nan?.should == true
-    BigDecimal("NaN").quo(BigDecimal("1")).nan?.should == true
+    BigDecimal("1").quo(BigDecimal("NaN")).should.nan?
+    BigDecimal("NaN").quo(BigDecimal("1")).should.nan?
   end
 end
diff --git a/spec/ruby/library/bigdecimal/remainder_spec.rb b/spec/ruby/library/bigdecimal/remainder_spec.rb
index 04233edece..27a2986570 100644
--- a/spec/ruby/library/bigdecimal/remainder_spec.rb
+++ b/spec/ruby/library/bigdecimal/remainder_spec.rb
@@ -37,9 +37,11 @@ describe "BigDecimal#remainder" do
     @neg_int.remainder(@pos_frac).should == @neg_int - @pos_frac * (@neg_int / @pos_frac).truncate
   end
 
-  it "returns NaN used with zero" do
-    @mixed.remainder(@zero).nan?.should == true
-    @zero.remainder(@zero).nan?.should == true
+  version_is BigDecimal::VERSION, "3.3.0" do
+    it "raises ZeroDivisionError used with zero" do
+      -> { @mixed.remainder(@zero) }.should.raise(ZeroDivisionError)
+      -> { @zero.remainder(@zero) }.should.raise(ZeroDivisionError)
+    end
   end
 
   it "returns zero if used on zero" do
@@ -47,28 +49,11 @@ describe "BigDecimal#remainder" do
   end
 
   it "returns NaN if NaN is involved" do
-    @nan.remainder(@nan).nan?.should == true
-    @nan.remainder(@one).nan?.should == true
-    @one.remainder(@nan).nan?.should == true
-    @infinity.remainder(@nan).nan?.should == true
-    @nan.remainder(@infinity).nan?.should == true
-  end
-
-  it "returns NaN if Infinity is involved" do
-    @infinity.remainder(@infinity).nan?.should == true
-    @infinity.remainder(@one).nan?.should == true
-    @infinity.remainder(@mixed).nan?.should == true
-    @infinity.remainder(@one_minus).nan?.should == true
-    @infinity.remainder(@frac_1).nan?.should == true
-    @one.remainder(@infinity).nan?.should == true
-
-    @infinity_minus.remainder(@infinity_minus).nan?.should == true
-    @infinity_minus.remainder(@one).nan?.should == true
-    @one.remainder(@infinity_minus).nan?.should == true
-    @frac_2.remainder(@infinity_minus).nan?.should == true
-
-    @infinity.remainder(@infinity_minus).nan?.should == true
-    @infinity_minus.remainder(@infinity).nan?.should == true
+    @nan.remainder(@nan).should.nan?
+    @nan.remainder(@one).should.nan?
+    @one.remainder(@nan).should.nan?
+    @infinity.remainder(@nan).should.nan?
+    @nan.remainder(@infinity).should.nan?
   end
 
   it "coerces arguments to BigDecimal if possible" do
@@ -86,7 +71,7 @@ describe "BigDecimal#remainder" do
   it "raises TypeError if the argument cannot be coerced to BigDecimal" do
     -> {
       @one.remainder('2')
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/round_spec.rb b/spec/ruby/library/bigdecimal/round_spec.rb
index 501a1a7342..622e129d93 100644
--- a/spec/ruby/library/bigdecimal/round_spec.rb
+++ b/spec/ruby/library/bigdecimal/round_spec.rb
@@ -217,18 +217,18 @@ describe "BigDecimal#round" do
   end
 
   it 'raise exception, if self is special value' do
-    -> { BigDecimal('NaN').round }.should raise_error(FloatDomainError)
-    -> { BigDecimal('Infinity').round }.should raise_error(FloatDomainError)
-    -> { BigDecimal('-Infinity').round }.should raise_error(FloatDomainError)
+    -> { BigDecimal('NaN').round }.should.raise(FloatDomainError)
+    -> { BigDecimal('Infinity').round }.should.raise(FloatDomainError)
+    -> { BigDecimal('-Infinity').round }.should.raise(FloatDomainError)
   end
 
   it 'do not raise exception, if self is special value and precision is given' do
-    -> { BigDecimal('NaN').round(2) }.should_not raise_error(FloatDomainError)
-    -> { BigDecimal('Infinity').round(2) }.should_not raise_error(FloatDomainError)
-    -> { BigDecimal('-Infinity').round(2) }.should_not raise_error(FloatDomainError)
+    -> { BigDecimal('NaN').round(2) }.should_not.raise(FloatDomainError)
+    -> { BigDecimal('Infinity').round(2) }.should_not.raise(FloatDomainError)
+    -> { BigDecimal('-Infinity').round(2) }.should_not.raise(FloatDomainError)
   end
 
-  it "raise for a non-existent round mode" do
-    -> { @p1_50.round(0, :nonsense) }.should raise_error(ArgumentError, "invalid rounding mode")
+  it 'raise for a non-existent round mode' do
+    -> { @p1_50.round(0, :nonsense) }.should.raise(ArgumentError, "invalid rounding mode (nonsense)")
   end
 end
diff --git a/spec/ruby/library/bigdecimal/shared/clone.rb b/spec/ruby/library/bigdecimal/shared/clone.rb
index e58df3a94b..03de6d0fc3 100644
--- a/spec/ruby/library/bigdecimal/shared/clone.rb
+++ b/spec/ruby/library/bigdecimal/shared/clone.rb
@@ -5,20 +5,9 @@ describe :bigdecimal_clone, shared: true do
     @obj = BigDecimal("1.2345")
   end
 
-  ruby_version_is "" ... "2.5" do
-    it "copies the BigDecimal's value to a newly allocated object" do
-      copy = @obj.public_send(@method)
+  it "returns self" do
+    copy = @obj.public_send(@method)
 
-      copy.should_not equal(@obj)
-      copy.should == @obj
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "returns self" do
-      copy = @obj.public_send(@method)
-
-      copy.should equal(@obj)
-    end
+    copy.should.equal?(@obj)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/shared/modulo.rb b/spec/ruby/library/bigdecimal/shared/modulo.rb
index 67c0ecf2fc..63470d0977 100644
--- a/spec/ruby/library/bigdecimal/shared/modulo.rb
+++ b/spec/ruby/library/bigdecimal/shared/modulo.rb
@@ -80,37 +80,43 @@ describe :bigdecimal_modulo, shared: true do
   end
 
   it "returns NaN if NaN is involved" do
-    @nan.send(@method, @nan).nan?.should == true
-    @nan.send(@method, @one).nan?.should == true
-    @one.send(@method, @nan).nan?.should == true
-    @infinity.send(@method, @nan).nan?.should == true
-    @nan.send(@method, @infinity).nan?.should == true
+    @nan.send(@method, @nan).should.nan?
+    @nan.send(@method, @one).should.nan?
+    @one.send(@method, @nan).should.nan?
+    @infinity.send(@method, @nan).should.nan?
+    @nan.send(@method, @infinity).should.nan?
   end
 
   it "returns NaN if the dividend is Infinity" do
-    @infinity.send(@method, @infinity).nan?.should == true
-    @infinity.send(@method, @one).nan?.should == true
-    @infinity.send(@method, @mixed).nan?.should == true
-    @infinity.send(@method, @one_minus).nan?.should == true
-    @infinity.send(@method, @frac_1).nan?.should == true
+    @infinity.send(@method, @infinity).should.nan?
+    @infinity.send(@method, @one).should.nan?
+    @infinity.send(@method, @mixed).should.nan?
+    @infinity.send(@method, @one_minus).should.nan?
+    @infinity.send(@method, @frac_1).should.nan?
 
-    @infinity_minus.send(@method, @infinity_minus).nan?.should == true
-    @infinity_minus.send(@method, @one).nan?.should == true
+    @infinity_minus.send(@method, @infinity_minus).should.nan?
+    @infinity_minus.send(@method, @one).should.nan?
 
-    @infinity.send(@method, @infinity_minus).nan?.should == true
-    @infinity_minus.send(@method, @infinity).nan?.should == true
+    @infinity.send(@method, @infinity_minus).should.nan?
+    @infinity_minus.send(@method, @infinity).should.nan?
   end
 
-  it "returns the dividend if the divisor is Infinity" do
-    @one.send(@method, @infinity).should == @one
-    @one.send(@method, @infinity_minus).should == @one
-    @frac_2.send(@method, @infinity_minus).should == @frac_2
+  version_is BigDecimal::VERSION, "3.3.0" do
+    it "returns the dividend if the divisor is Infinity and signs are same" do
+      @one.send(@method, @infinity).should == @one
+      (-@frac_2).send(@method, @infinity_minus).should == -@frac_2
+    end
+
+    it "returns the divisor if the divisor is Infinity and signs are different" do
+      (-@one).send(@method, @infinity).should == @infinity
+      @frac_2.send(@method, @infinity_minus).should == @infinity_minus
+    end
   end
 
   it "raises TypeError if the argument cannot be coerced to BigDecimal" do
     -> {
       @one.send(@method, '2')
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 end
 
@@ -118,8 +124,8 @@ describe :bigdecimal_modulo_zerodivisionerror, shared: true do
   it "raises ZeroDivisionError if other is zero" do
     bd5667 = BigDecimal("5667.19")
 
-    -> { bd5667.send(@method, 0) }.should raise_error(ZeroDivisionError)
-    -> { bd5667.send(@method, BigDecimal("0")) }.should raise_error(ZeroDivisionError)
-    -> { @zero.send(@method, @zero) }.should raise_error(ZeroDivisionError)
+    -> { bd5667.send(@method, 0) }.should.raise(ZeroDivisionError)
+    -> { bd5667.send(@method, BigDecimal("0")) }.should.raise(ZeroDivisionError)
+    -> { @zero.send(@method, @zero) }.should.raise(ZeroDivisionError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/shared/mult.rb b/spec/ruby/library/bigdecimal/shared/mult.rb
index b94c9385de..c613df04c4 100644
--- a/spec/ruby/library/bigdecimal/shared/mult.rb
+++ b/spec/ruby/library/bigdecimal/shared/mult.rb
@@ -51,8 +51,8 @@ describe :bigdecimal_mult, shared: true do
     values = @regular_vals + @zeroes
 
     values.each do |val|
-      @nan.send(@method, val, *@object).nan?.should == true
-      val.send(@method, @nan, *@object).nan?.should == true
+      @nan.send(@method, val, *@object).should.nan?
+      val.send(@method, @nan, *@object).should.nan?
     end
   end
 
@@ -62,9 +62,9 @@ describe :bigdecimal_mult, shared: true do
     values.each do |val|
       @zeroes.each do |zero|
         zero.send(@method, val, *@object).should == 0
-        zero.send(@method, val, *@object).zero?.should == true
+        zero.send(@method, val, *@object).should.zero?
         val.send(@method, zero, *@object).should == 0
-        val.send(@method, zero, *@object).zero?.should == true
+        val.send(@method, zero, *@object).should.zero?
       end
     end
   end
@@ -75,8 +75,8 @@ describe :bigdecimal_mult, shared: true do
 
     values.each do |val|
       infs.each do |inf|
-        inf.send(@method, val, *@object).finite?.should == false
-        val.send(@method, inf, *@object).finite?.should == false
+        inf.send(@method, val, *@object).should_not.finite?
+        val.send(@method, inf, *@object).should_not.finite?
       end
     end
 
@@ -89,9 +89,9 @@ describe :bigdecimal_mult, shared: true do
   end
 
   it "returns NaN if the result is undefined" do
-    @zero.send(@method, @infinity, *@object).nan?.should == true
-    @zero.send(@method, @infinity_minus, *@object).nan?.should == true
-    @infinity.send(@method, @zero, *@object).nan?.should == true
-    @infinity_minus.send(@method, @zero, *@object).nan?.should == true
+    @zero.send(@method, @infinity, *@object).should.nan?
+    @zero.send(@method, @infinity_minus, *@object).should.nan?
+    @infinity.send(@method, @zero, *@object).should.nan?
+    @infinity_minus.send(@method, @zero, *@object).should.nan?
   end
 end
diff --git a/spec/ruby/library/bigdecimal/shared/power.rb b/spec/ruby/library/bigdecimal/shared/power.rb
index a4848fb2e2..6dafb638e2 100644
--- a/spec/ruby/library/bigdecimal/shared/power.rb
+++ b/spec/ruby/library/bigdecimal/shared/power.rb
@@ -10,8 +10,8 @@ describe :bigdecimal_power, shared: true do
     e = BigDecimal("1.00000000000000000000123456789")
     one = BigDecimal("1")
     ten = BigDecimal("10")
-    # The tolerance is dependent upon the size of BASE_FIG
-    tolerance = BigDecimal("1E-70")
+    # Accuracy is at least ndigits(== 30) + DOUBLE_FIG(== 16)
+    tolerance = BigDecimal("1E-46")
     ten_powers = BigDecimal("1E10000")
     pi = BigDecimal("3.14159265358979")
     e3_minus.send(@method, 2).should == e3_minus_power_2
@@ -53,8 +53,8 @@ describe :bigdecimal_power, shared: true do
   end
 
   it "returns NaN if self is NaN" do
-    BigDecimal("NaN").send(@method, -5).nan?.should == true
-    BigDecimal("NaN").send(@method, 5).nan?.should == true
+    BigDecimal("NaN").send(@method, -5).should.nan?
+    BigDecimal("NaN").send(@method, 5).should.nan?
   end
 
   it "returns 0.0 if self is infinite and argument is negative" do
diff --git a/spec/ruby/library/bigdecimal/shared/quo.rb b/spec/ruby/library/bigdecimal/shared/quo.rb
index 4d6d64b787..18ff2fe9a5 100644
--- a/spec/ruby/library/bigdecimal/shared/quo.rb
+++ b/spec/ruby/library/bigdecimal/shared/quo.rb
@@ -31,6 +31,7 @@ describe :bigdecimal_quo, shared: true do
 
   describe "with Object" do
     it "tries to coerce the other operand to self" do
+      skip if @method == :div
       object = mock("Object")
       object.should_receive(:coerce).with(@one).and_return([@one, @two])
       @one.send(@method, object, *@object).should == BigDecimal("0.5")
@@ -49,8 +50,8 @@ describe :bigdecimal_quo, shared: true do
   end
 
   it "returns NaN if Infinity / ((+|-) Infinity)" do
-    @infinity.send(@method, @infinity_minus, *@object).nan?.should == true
-    @infinity_minus.send(@method, @infinity, *@object).nan?.should == true
+    @infinity.send(@method, @infinity_minus, *@object).should.nan?
+    @infinity_minus.send(@method, @infinity, *@object).should.nan?
   end
 
   it "returns (+|-) Infinity if divided by zero" do
@@ -60,8 +61,8 @@ describe :bigdecimal_quo, shared: true do
   end
 
   it "returns NaN if zero is divided by zero" do
-    @zero.send(@method, @zero, *@object).nan?.should == true
-    @zero_minus.send(@method, @zero_plus, *@object).nan?.should == true
-    @zero_plus.send(@method, @zero_minus, *@object).nan?.should == true
+    @zero.send(@method, @zero, *@object).should.nan?
+    @zero_minus.send(@method, @zero_plus, *@object).should.nan?
+    @zero_plus.send(@method, @zero_minus, *@object).should.nan?
   end
 end
diff --git a/spec/ruby/library/bigdecimal/shared/to_int.rb b/spec/ruby/library/bigdecimal/shared/to_int.rb
index 02f6092f23..3c9f3b4f97 100644
--- a/spec/ruby/library/bigdecimal/shared/to_int.rb
+++ b/spec/ruby/library/bigdecimal/shared/to_int.rb
@@ -1,12 +1,12 @@
 require 'bigdecimal'
 
-describe :bigdecimal_to_int , shared: true do
+describe :bigdecimal_to_int, shared: true do
   it "raises FloatDomainError if BigDecimal is infinity or NaN" do
-    -> { BigDecimal("Infinity").send(@method) }.should raise_error(FloatDomainError)
-    -> { BigDecimal("NaN").send(@method) }.should raise_error(FloatDomainError)
+    -> { BigDecimal("Infinity").send(@method) }.should.raise(FloatDomainError)
+    -> { BigDecimal("NaN").send(@method) }.should.raise(FloatDomainError)
   end
 
-  it "returns Integer or Bignum otherwise" do
+  it "returns Integer otherwise" do
     BigDecimal("3E-20001").send(@method).should == 0
     BigDecimal("2E4000").send(@method).should == 2 * 10 ** 4000
     BigDecimal("2").send(@method).should == 2
diff --git a/spec/ruby/library/bigdecimal/split_spec.rb b/spec/ruby/library/bigdecimal/split_spec.rb
index f9b4bab5f7..53b1f649d9 100644
--- a/spec/ruby/library/bigdecimal/split_spec.rb
+++ b/spec/ruby/library/bigdecimal/split_spec.rb
@@ -58,16 +58,16 @@ describe "BigDecimal#split" do
   end
 
   it "third value: the base (currently always ten)" do
-   @arr[2].should == 10
-   @arr_neg[2].should == 10
-   @arr_big[2].should == 10
-   @arr_big_neg[2].should == 10
-   @huge[2].should == 10
-   @infinity.split[2].should == 10
-   @nan.split[2].should == 10
-   @infinity_neg.split[2].should == 10
-   @zero.split[2].should == 10
-   @zero_neg.split[2].should == 10
+    @arr[2].should == 10
+    @arr_neg[2].should == 10
+    @arr_big[2].should == 10
+    @arr_big_neg[2].should == 10
+    @huge[2].should == 10
+    @infinity.split[2].should == 10
+    @nan.split[2].should == 10
+    @infinity_neg.split[2].should == 10
+    @zero.split[2].should == 10
+    @zero_neg.split[2].should == 10
   end
 
   it "fourth value: the exponent" do
diff --git a/spec/ruby/library/bigdecimal/sqrt_spec.rb b/spec/ruby/library/bigdecimal/sqrt_spec.rb
index d149003b9f..1f3ef9a8c3 100644
--- a/spec/ruby/library/bigdecimal/sqrt_spec.rb
+++ b/spec/ruby/library/bigdecimal/sqrt_spec.rb
@@ -36,44 +36,46 @@ describe "BigDecimal#sqrt" do
     BigDecimal('121').sqrt(5).should be_close(11, 0.00001)
   end
 
-  it "returns square root of 0.9E-99999 with desired precision" do
-    @frac_2.sqrt(1).to_s.should =~ /\A0\.3E-49999\z/i
+  platform_is_not c_long_size: 32 do # fails on i686
+    it "returns square root of 0.9E-99999 with desired precision" do
+      @frac_2.sqrt(1).to_s.should =~ /\A0\.3E-49999\z/i
+    end
   end
 
   it "raises ArgumentError when no argument is given" do
     -> {
       @one.sqrt
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if a negative number is given" do
     -> {
       @one.sqrt(-1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError if 2 arguments are given" do
     -> {
       @one.sqrt(1, 1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises TypeError if nil is given" do
     -> {
       @one.sqrt(nil)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises TypeError if a string is given" do
     -> {
       @one.sqrt("stuff")
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises TypeError if a plain Object is given" do
     -> {
       @one.sqrt(Object.new)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "returns 1 if precision is 0 or 1" do
@@ -84,7 +86,7 @@ describe "BigDecimal#sqrt" do
   it "raises FloatDomainError on negative values" do
     -> {
       BigDecimal('-1').sqrt(10)
-    }.should raise_error(FloatDomainError)
+    }.should.raise(FloatDomainError)
   end
 
   it "returns positive infinity for infinity" do
@@ -94,13 +96,13 @@ describe "BigDecimal#sqrt" do
   it "raises FloatDomainError for negative infinity" do
     -> {
       @infinity_minus.sqrt(1)
-    }.should raise_error(FloatDomainError)
+    }.should.raise(FloatDomainError)
   end
 
   it "raises FloatDomainError for NaN" do
     -> {
       @nan.sqrt(1)
-    }.should raise_error(FloatDomainError)
+    }.should.raise(FloatDomainError)
   end
 
   it "returns 0 for 0, +0.0 and -0.0" do
diff --git a/spec/ruby/library/bigdecimal/sub_spec.rb b/spec/ruby/library/bigdecimal/sub_spec.rb
index 29ec851193..3b62a0c794 100644
--- a/spec/ruby/library/bigdecimal/sub_spec.rb
+++ b/spec/ruby/library/bigdecimal/sub_spec.rb
@@ -35,14 +35,6 @@ describe "BigDecimal#sub" do
     @frac_1.sub(@frac_1, 1000000).should == @zero
   end
 
-  describe "with Object" do
-    it "tries to coerce the other operand to self" do
-      object = mock("Object")
-      object.should_receive(:coerce).with(@frac_3).and_return([@frac_3, @frac_4])
-      @frac_3.sub(object, 1).should == BigDecimal("-0.9E15")
-    end
-  end
-
   describe "with Rational" do
     it "produces a BigDecimal" do
       (@three - Rational(500, 2)).should == BigDecimal('-0.247e3')
@@ -50,13 +42,13 @@ describe "BigDecimal#sub" do
   end
 
   it "returns NaN if NaN is involved" do
-    @one.sub(@nan, 1).nan?.should == true
-    @nan.sub(@one, 1).nan?.should == true
+    @one.sub(@nan, 1).should.nan?
+    @nan.sub(@one, 1).should.nan?
   end
 
   it "returns NaN if both values are infinite with the same signs" do
-    @infinity.sub(@infinity, 1).nan?.should == true
-    @infinity_minus.sub(@infinity_minus, 1).nan?.should == true
+    @infinity.sub(@infinity, 1).should.nan?
+    @infinity_minus.sub(@infinity_minus, 1).should.nan?
   end
 
   it "returns Infinity or -Infinity if these are involved" do
diff --git a/spec/ruby/library/bigdecimal/to_f_spec.rb b/spec/ruby/library/bigdecimal/to_f_spec.rb
index 1cc25d5c40..f5220d995a 100644
--- a/spec/ruby/library/bigdecimal/to_f_spec.rb
+++ b/spec/ruby/library/bigdecimal/to_f_spec.rb
@@ -20,9 +20,9 @@ describe "BigDecimal#to_f" do
   end
 
   it "returns number of type float" do
-    BigDecimal("3.14159").to_f.should be_kind_of(Float)
-    @vals.each { |val| val.to_f.should be_kind_of(Float) }
-    @spec_vals.each { |val| val.to_f.should be_kind_of(Float) }
+    BigDecimal("3.14159").to_f.should.is_a?(Float)
+    @vals.each { |val| val.to_f.should.is_a?(Float) }
+    @spec_vals.each { |val| val.to_f.should.is_a?(Float) }
   end
 
   it "rounds correctly to Float precision" do
@@ -41,7 +41,7 @@ describe "BigDecimal#to_f" do
     @zero.to_f.should == 0
     @zero.to_f.to_s.should == "0.0"
 
-    @nan.to_f.nan?.should == true
+    @nan.to_f.should.nan?
 
     @infinity.to_f.infinite?.should == 1
     @infinity_minus.to_f.infinite?.should == -1
diff --git a/spec/ruby/library/bigdecimal/to_i_spec.rb b/spec/ruby/library/bigdecimal/to_i_spec.rb
index 09481fce15..e5e65c562e 100644
--- a/spec/ruby/library/bigdecimal/to_i_spec.rb
+++ b/spec/ruby/library/bigdecimal/to_i_spec.rb
@@ -3,5 +3,5 @@ require_relative 'shared/to_int'
 require 'bigdecimal'
 
 describe "BigDecimal#to_i" do
-    it_behaves_like :bigdecimal_to_int, :to_i
+  it_behaves_like :bigdecimal_to_int, :to_i
 end
diff --git a/spec/ruby/library/bigdecimal/to_r_spec.rb b/spec/ruby/library/bigdecimal/to_r_spec.rb
index 91d2b33993..a112c002ef 100644
--- a/spec/ruby/library/bigdecimal/to_r_spec.rb
+++ b/spec/ruby/library/bigdecimal/to_r_spec.rb
@@ -4,13 +4,25 @@ require 'bigdecimal'
 describe "BigDecimal#to_r" do
 
   it "returns a Rational" do
-    BigDecimal("3.14159").to_r.should be_kind_of(Rational)
+    BigDecimal("3.14159").to_r.should.is_a?(Rational)
   end
 
   it "returns a Rational with bignum values" do
     r = BigDecimal("3.141592653589793238462643").to_r
-    r.numerator.should eql(3141592653589793238462643)
-    r.denominator.should eql(1000000000000000000000000)
+    r.numerator.should.eql?(3141592653589793238462643)
+    r.denominator.should.eql?(1000000000000000000000000)
+  end
+
+  it "returns a Rational from a BigDecimal with an exponent" do
+    r = BigDecimal("1E2").to_r
+    r.numerator.should.eql?(100)
+    r.denominator.should.eql?(1)
+  end
+
+  it "returns a Rational from a negative BigDecimal with an exponent" do
+    r = BigDecimal("-1E2").to_r
+    r.numerator.should.eql?(-100)
+    r.denominator.should.eql?(1)
   end
 
 end
diff --git a/spec/ruby/library/bigdecimal/to_s_spec.rb b/spec/ruby/library/bigdecimal/to_s_spec.rb
index b6154c680d..5ec54765b5 100644
--- a/spec/ruby/library/bigdecimal/to_s_spec.rb
+++ b/spec/ruby/library/bigdecimal/to_s_spec.rb
@@ -8,6 +8,11 @@ describe "BigDecimal#to_s" do
     @bigneg_str = "-3.1415926535897932384626433832795028841971693993"
     @bigdec = BigDecimal(@bigdec_str)
     @bigneg = BigDecimal(@bigneg_str)
+    @internal = Encoding.default_internal
+  end
+
+  after :each do
+    Encoding.default_internal = @internal
   end
 
   it "return type is of class String" do
@@ -26,7 +31,7 @@ describe "BigDecimal#to_s" do
   end
 
   it "takes an optional argument" do
-    -> {@bigdec.to_s("F")}.should_not raise_error()
+    -> {@bigdec.to_s("F")}.should_not.raise()
   end
 
   it "starts with + if + is supplied and value is positive" do
@@ -34,9 +39,9 @@ describe "BigDecimal#to_s" do
     @bigneg.to_s("+").should_not =~ /^\+.*/
   end
 
-  it "inserts a space every n chars, if integer n is supplied" do
+  it "inserts a space every n chars to fraction part, if integer n is supplied" do
     re =\
-      /\A0\.314 159 265 358 979 323 846 264 338 327 950 288 419 716 939 937E1\z/i
+    /\A0\.314 159 265 358 979 323 846 264 338 327 950 288 419 716 939 937E1\z/i
     @bigdec.to_s(3).should =~ re
 
     str1 = '-123.45678 90123 45678 9'
@@ -47,6 +52,10 @@ describe "BigDecimal#to_s" do
     BigDecimal("1.2345").to_s('0F').should == "1.2345"
   end
 
+  it "inserts a space every n chars to integer part, if integer n is supplied" do
+    BigDecimal('1000010').to_s('5F').should == "10 00010.0"
+  end
+
   it "can return a leading space for values > 0" do
     @bigdec.to_s(" F").should =~ /\ .*/
     @bigneg.to_s(" F").should_not =~ /\ .*/
@@ -77,4 +86,13 @@ describe "BigDecimal#to_s" do
     end
   end
 
+  it "returns a String in US-ASCII encoding when Encoding.default_internal is nil" do
+    Encoding.default_internal = nil
+    BigDecimal('1.23').to_s.encoding.should.equal?(Encoding::US_ASCII)
+  end
+
+  it "returns a String in US-ASCII encoding when Encoding.default_internal is not nil" do
+    Encoding.default_internal = Encoding::IBM437
+    BigDecimal('1.23').to_s.encoding.should.equal?(Encoding::US_ASCII)
+  end
 end
diff --git a/spec/ruby/library/bigdecimal/truncate_spec.rb b/spec/ruby/library/bigdecimal/truncate_spec.rb
index d3a15f62c7..cedc662aeb 100644
--- a/spec/ruby/library/bigdecimal/truncate_spec.rb
+++ b/spec/ruby/library/bigdecimal/truncate_spec.rb
@@ -4,11 +4,11 @@ require 'bigdecimal'
 describe "BigDecimal#truncate" do
 
   before :each do
-      @arr = ['3.14159', '8.7', "0.314159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593014782083152134043E1"]
-      @big = BigDecimal("123456.789")
-      @nan = BigDecimal('NaN')
-      @infinity = BigDecimal('Infinity')
-      @infinity_negative = BigDecimal('-Infinity')
+    @arr = ['3.14159', '8.7', "0.314159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593014782083152134043E1"]
+    @big = BigDecimal("123456.789")
+    @nan = BigDecimal('NaN')
+    @infinity = BigDecimal('Infinity')
+    @infinity_negative = BigDecimal('-Infinity')
   end
 
   it "returns value of type Integer." do
@@ -58,9 +58,9 @@ describe "BigDecimal#truncate" do
   end
 
   it "returns NaN if self is NaN" do
-    @nan.truncate(-1).nan?.should == true
-    @nan.truncate(+1).nan?.should == true
-    @nan.truncate(0).nan?.should == true
+    @nan.truncate(-1).should.nan?
+    @nan.truncate(+1).should.nan?
+    @nan.truncate(0).should.nan?
   end
 
   it "returns Infinity if self is infinite" do
@@ -74,8 +74,8 @@ describe "BigDecimal#truncate" do
   end
 
   it "returns the same value if self is special value" do
-    -> { @nan.truncate }.should raise_error(FloatDomainError)
-    -> { @infinity.truncate }.should raise_error(FloatDomainError)
-    -> { @infinity_negative.truncate }.should raise_error(FloatDomainError)
+    -> { @nan.truncate }.should.raise(FloatDomainError)
+    -> { @infinity.truncate }.should.raise(FloatDomainError)
+    -> { @infinity_negative.truncate }.should.raise(FloatDomainError)
   end
 end
diff --git a/spec/ruby/library/bigdecimal/uminus_spec.rb b/spec/ruby/library/bigdecimal/uminus_spec.rb
index 5e2a786c4c..c780cdfac5 100644
--- a/spec/ruby/library/bigdecimal/uminus_spec.rb
+++ b/spec/ruby/library/bigdecimal/uminus_spec.rb
@@ -53,6 +53,6 @@ describe "BigDecimal#-@" do
     @zero_neg.send(:-@).should == @zero
     @zero_neg.send(:-@).sign.should == 1
 
-    @nan.send(:-@).nan?.should == true
+    @nan.send(:-@).should.nan?
   end
 end
diff --git a/spec/ruby/library/bigdecimal/util_spec.rb b/spec/ruby/library/bigdecimal/util_spec.rb
index f41e131144..69663d4bd2 100644
--- a/spec/ruby/library/bigdecimal/util_spec.rb
+++ b/spec/ruby/library/bigdecimal/util_spec.rb
@@ -20,17 +20,15 @@ describe "BigDecimal's util method definitions" do
 
     it "should define #to_d on BigDecimal" do
       bd = BigDecimal("3.14")
-      bd.to_d.should equal(bd)
+      bd.to_d.should.equal?(bd)
     end
 
     it "should define #to_d on Rational" do
       Rational(22, 7).to_d(3).should == BigDecimal(3.14, 3)
     end
 
-    ruby_version_is "2.6" do
-      it "should define #to_d on nil" do
-        nil.to_d.should == BigDecimal(0)
-      end
+    it "should define #to_d on nil" do
+      nil.to_d.should == BigDecimal(0)
     end
   end
 
diff --git a/spec/ruby/library/bigdecimal/zero_spec.rb b/spec/ruby/library/bigdecimal/zero_spec.rb
index c5d3acb8c3..2563210939 100644
--- a/spec/ruby/library/bigdecimal/zero_spec.rb
+++ b/spec/ruby/library/bigdecimal/zero_spec.rb
@@ -6,22 +6,22 @@ describe "BigDecimal#zero?" do
   it "returns true if self does equal zero" do
     really_small_zero = BigDecimal("0E-200000000")
     really_big_zero = BigDecimal("0E200000000000")
-    really_small_zero.zero?.should == true
-    really_big_zero.zero?.should == true
-    BigDecimal("0.000000000000000000000000").zero?.should == true
-    BigDecimal("0").zero?.should == true
-    BigDecimal("0E0").zero?.should == true
-    BigDecimal("+0").zero?.should == true
-    BigDecimal("-0").zero?.should == true
+    really_small_zero.should.zero?
+    really_big_zero.should.zero?
+    BigDecimal("0.000000000000000000000000").should.zero?
+    BigDecimal("0").should.zero?
+    BigDecimal("0E0").should.zero?
+    BigDecimal("+0").should.zero?
+    BigDecimal("-0").should.zero?
   end
 
   it "returns false otherwise" do
-    BigDecimal("0000000001").zero?.should == false
-    BigDecimal("2E40001").zero?.should == false
-    BigDecimal("3E-20001").zero?.should == false
-    BigDecimal("Infinity").zero?.should == false
-    BigDecimal("-Infinity").zero?.should == false
-    BigDecimal("NaN").zero?.should == false
+    BigDecimal("0000000001").should_not.zero?
+    BigDecimal("2E40001").should_not.zero?
+    BigDecimal("3E-20001").should_not.zero?
+    BigDecimal("Infinity").should_not.zero?
+    BigDecimal("-Infinity").should_not.zero?
+    BigDecimal("NaN").should_not.zero?
   end
 
 end
diff --git a/spec/ruby/library/bigmath/log_spec.rb b/spec/ruby/library/bigmath/log_spec.rb
deleted file mode 100644
index 2ffbf8b6b9..0000000000
--- a/spec/ruby/library/bigmath/log_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../spec_helper'
-require 'bigdecimal'
-
-describe "BigDecimal#log" do
-  it "handles high-precision Rational arguments" do
-    result = BigDecimal('0.22314354220170971436137296411949880462556361100856391620766259404746040597133837784E0')
-    r = Rational(1_234_567_890, 987_654_321)
-    BigMath.log(r, 50).should == result
-  end
-end
diff --git a/spec/ruby/library/cgi/cookie/domain_spec.rb b/spec/ruby/library/cgi/cookie/domain_spec.rb
index 962609ebaf..c118ef6383 100644
--- a/spec/ruby/library/cgi/cookie/domain_spec.rb
+++ b/spec/ruby/library/cgi/cookie/domain_spec.rb
@@ -1,23 +1,26 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#domain" do
-  it "returns self's domain" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.domain.should be_nil
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("name" => "test-cookie", "domain" => "example.com")
-    cookie.domain.should == "example.com"
+  describe "CGI::Cookie#domain" do
+    it "returns self's domain" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.domain.should == nil
+
+      cookie = CGI::Cookie.new("name" => "test-cookie", "domain" => "example.com")
+      cookie.domain.should == "example.com"
+    end
   end
-end
 
-describe "CGI::Cookie#domain=" do
-  it "sets self's domain" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.domain = "test.com"
-    cookie.domain.should == "test.com"
+  describe "CGI::Cookie#domain=" do
+    it "sets self's domain" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.domain = "test.com"
+      cookie.domain.should == "test.com"
 
-    cookie.domain = "example.com"
-    cookie.domain.should == "example.com"
+      cookie.domain = "example.com"
+      cookie.domain.should == "example.com"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/expires_spec.rb b/spec/ruby/library/cgi/cookie/expires_spec.rb
index c8f26d01cd..b9cc7d5b65 100644
--- a/spec/ruby/library/cgi/cookie/expires_spec.rb
+++ b/spec/ruby/library/cgi/cookie/expires_spec.rb
@@ -1,23 +1,26 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#expires" do
-  it "returns self's expiration date" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.expires.should be_nil
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("name" => "test-cookie", "expires" => Time.at(1196524602))
-    cookie.expires.should == Time.at(1196524602)
+  describe "CGI::Cookie#expires" do
+    it "returns self's expiration date" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.expires.should == nil
+
+      cookie = CGI::Cookie.new("name" => "test-cookie", "expires" => Time.at(1196524602))
+      cookie.expires.should == Time.at(1196524602)
+    end
   end
-end
 
-describe "CGI::Cookie#expires=" do
-  it "sets self's expiration date" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.expires = Time.at(1196524602)
-    cookie.expires.should == Time.at(1196524602)
+  describe "CGI::Cookie#expires=" do
+    it "sets self's expiration date" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.expires = Time.at(1196524602)
+      cookie.expires.should == Time.at(1196524602)
 
-    cookie.expires = Time.at(1196525000)
-    cookie.expires.should == Time.at(1196525000)
+      cookie.expires = Time.at(1196525000)
+      cookie.expires.should == Time.at(1196525000)
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/initialize_spec.rb b/spec/ruby/library/cgi/cookie/initialize_spec.rb
index 4b6e104b10..80bc2c2196 100644
--- a/spec/ruby/library/cgi/cookie/initialize_spec.rb
+++ b/spec/ruby/library/cgi/cookie/initialize_spec.rb
@@ -1,147 +1,150 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#initialize when passed String" do
-  before :each do
-    @cookie = CGI::Cookie.allocate
-  end
-
-  it "sets the self's name to the passed String" do
-    @cookie.send(:initialize, "test-cookie")
-    @cookie.name.should == "test-cookie"
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  it "sets the self's value to an empty Array" do
-    @cookie.send(:initialize, "test-cookie")
-    @cookie.value.should == []
-  end
-
-  it "sets self to a non-secure cookie" do
-    @cookie.send(:initialize, "test")
-    @cookie.secure.should be_false
-  end
-
-  it "does set self's path to an empty String when ENV[\"SCRIPT_NAME\"] is not set" do
-    @cookie.send(:initialize, "test-cookie")
-    @cookie.path.should == ""
-  end
-
-  it "does set self's path based on ENV[\"SCRIPT_NAME\"] when ENV[\"SCRIPT_NAME\"] is set" do
-    old_script_name = ENV["SCRIPT_NAME"]
+  describe "CGI::Cookie#initialize when passed String" do
+    before :each do
+      @cookie = CGI::Cookie.allocate
+    end
 
-    begin
-      ENV["SCRIPT_NAME"] = "some/path/script.rb"
+    it "sets the self's name to the passed String" do
       @cookie.send(:initialize, "test-cookie")
-      @cookie.path.should == "some/path/"
+      @cookie.name.should == "test-cookie"
+    end
 
-      ENV["SCRIPT_NAME"] = "script.rb"
+    it "sets the self's value to an empty Array" do
       @cookie.send(:initialize, "test-cookie")
-      @cookie.path.should == ""
+      @cookie.value.should == []
+    end
 
-      ENV["SCRIPT_NAME"] = nil
+    it "sets self to a non-secure cookie" do
+      @cookie.send(:initialize, "test")
+      @cookie.secure.should == false
+    end
+
+    it "does set self's path to an empty String when ENV[\"SCRIPT_NAME\"] is not set" do
       @cookie.send(:initialize, "test-cookie")
       @cookie.path.should == ""
-    ensure
-      ENV["SCRIPT_NAME"] = old_script_name
     end
-  end
 
-  it "does not set self's expiration date" do
-    @cookie.expires.should be_nil
-  end
+    it "does set self's path based on ENV[\"SCRIPT_NAME\"] when ENV[\"SCRIPT_NAME\"] is set" do
+      old_script_name = ENV["SCRIPT_NAME"]
 
-  it "does not set self's domain" do
-    @cookie.domain.should be_nil
-  end
-end
+      begin
+        ENV["SCRIPT_NAME"] = "some/path/script.rb"
+        @cookie.send(:initialize, "test-cookie")
+        @cookie.path.should == "some/path/"
 
-describe "CGI::Cookie#initialize when passed Hash" do
-  before :each do
-    @cookie = CGI::Cookie.allocate
-  end
+        ENV["SCRIPT_NAME"] = "script.rb"
+        @cookie.send(:initialize, "test-cookie")
+        @cookie.path.should == ""
+
+        ENV["SCRIPT_NAME"] = nil
+        @cookie.send(:initialize, "test-cookie")
+        @cookie.path.should == ""
+      ensure
+        ENV["SCRIPT_NAME"] = old_script_name
+      end
+    end
+
+    it "does not set self's expiration date" do
+      @cookie.expires.should == nil
+    end
 
-  it "sets self's contents based on the passed Hash" do
-    @cookie.send(:initialize,
-      'name'    => 'test-cookie',
-      'value'   => ["one", "two", "three"],
-      'path'    => 'some/path/',
-      'domain'  => 'example.com',
-      'expires' => Time.at(1196524602),
-      'secure'  => true)
-
-    @cookie.name.should == "test-cookie"
-    @cookie.value.should == ["one", "two", "three"]
-    @cookie.path.should == "some/path/"
-    @cookie.domain.should == "example.com"
-    @cookie.expires.should == Time.at(1196524602)
-    @cookie.secure.should be_true
+    it "does not set self's domain" do
+      @cookie.domain.should == nil
+    end
   end
 
-  it "does set self's path based on ENV[\"SCRIPT_NAME\"] when the Hash has no 'path' entry" do
-    old_script_name = ENV["SCRIPT_NAME"]
+  describe "CGI::Cookie#initialize when passed Hash" do
+    before :each do
+      @cookie = CGI::Cookie.allocate
+    end
 
-    begin
-      ENV["SCRIPT_NAME"] = "some/path/script.rb"
-      @cookie.send(:initialize, 'name' => 'test-cookie')
+    it "sets self's contents based on the passed Hash" do
+      @cookie.send(:initialize,
+        'name'    => 'test-cookie',
+        'value'   => ["one", "two", "three"],
+        'path'    => 'some/path/',
+        'domain'  => 'example.com',
+        'expires' => Time.at(1196524602),
+        'secure'  => true)
+
+      @cookie.name.should == "test-cookie"
+      @cookie.value.should == ["one", "two", "three"]
       @cookie.path.should == "some/path/"
+      @cookie.domain.should == "example.com"
+      @cookie.expires.should == Time.at(1196524602)
+      @cookie.secure.should == true
+    end
 
-      ENV["SCRIPT_NAME"] = "script.rb"
-      @cookie.send(:initialize, 'name' => 'test-cookie')
-      @cookie.path.should == ""
+    it "does set self's path based on ENV[\"SCRIPT_NAME\"] when the Hash has no 'path' entry" do
+      old_script_name = ENV["SCRIPT_NAME"]
 
-      ENV["SCRIPT_NAME"] = nil
-      @cookie.send(:initialize, 'name' => 'test-cookie')
-      @cookie.path.should == ""
-    ensure
-      ENV["SCRIPT_NAME"] = old_script_name
+      begin
+        ENV["SCRIPT_NAME"] = "some/path/script.rb"
+        @cookie.send(:initialize, 'name' => 'test-cookie')
+        @cookie.path.should == "some/path/"
+
+        ENV["SCRIPT_NAME"] = "script.rb"
+        @cookie.send(:initialize, 'name' => 'test-cookie')
+        @cookie.path.should == ""
+
+        ENV["SCRIPT_NAME"] = nil
+        @cookie.send(:initialize, 'name' => 'test-cookie')
+        @cookie.path.should == ""
+      ensure
+        ENV["SCRIPT_NAME"] = old_script_name
+      end
     end
-  end
 
-  it "tries to convert the Hash's 'value' to an Array using #Array" do
-    obj = mock("Converted To Array")
-    obj.should_receive(:to_ary).and_return(["1", "2", "3"])
-    @cookie.send(:initialize,
-      'name'  => 'test-cookie',
-      'value' => obj)
-    @cookie.value.should == [ "1", "2", "3" ]
-
-    obj = mock("Converted To Array")
-    obj.should_receive(:to_a).and_return(["one", "two", "three"])
-    @cookie.send(:initialize,
-      'name'  => 'test-cookie',
-      'value' => obj)
-    @cookie.value.should == [ "one", "two", "three" ]
-
-    obj = mock("Put into an Array")
-    @cookie.send(:initialize,
-      'name'  => 'test-cookie',
-      'value' => obj)
-    @cookie.value.should == [ obj ]
-  end
+    it "tries to convert the Hash's 'value' to an Array using #Array" do
+      obj = mock("Converted To Array")
+      obj.should_receive(:to_ary).and_return(["1", "2", "3"])
+      @cookie.send(:initialize,
+        'name'  => 'test-cookie',
+        'value' => obj)
+      @cookie.value.should == [ "1", "2", "3" ]
+
+      obj = mock("Converted To Array")
+      obj.should_receive(:to_a).and_return(["one", "two", "three"])
+      @cookie.send(:initialize,
+        'name'  => 'test-cookie',
+        'value' => obj)
+      @cookie.value.should == [ "one", "two", "three" ]
+
+      obj = mock("Put into an Array")
+      @cookie.send(:initialize,
+        'name'  => 'test-cookie',
+        'value' => obj)
+      @cookie.value.should == [ obj ]
+    end
 
-  it "raises a ArgumentError when the passed Hash has no 'name' entry" do
-    -> { @cookie.send(:initialize, {}) }.should raise_error(ArgumentError)
-    -> { @cookie.send(:initialize, "value" => "test") }.should raise_error(ArgumentError)
+    it "raises a ArgumentError when the passed Hash has no 'name' entry" do
+      -> { @cookie.send(:initialize, {}) }.should.raise(ArgumentError)
+      -> { @cookie.send(:initialize, "value" => "test") }.should.raise(ArgumentError)
+    end
   end
-end
 
-describe "CGI::Cookie#initialize when passed String, values ..." do
-  before :each do
-    @cookie = CGI::Cookie.allocate
-  end
+  describe "CGI::Cookie#initialize when passed String, values ..." do
+    before :each do
+      @cookie = CGI::Cookie.allocate
+    end
 
-  it "sets the self's name to the passed String" do
-    @cookie.send(:initialize, "test-cookie", "one", "two", "three")
-    @cookie.name.should == "test-cookie"
-  end
+    it "sets the self's name to the passed String" do
+      @cookie.send(:initialize, "test-cookie", "one", "two", "three")
+      @cookie.name.should == "test-cookie"
+    end
 
-  it "sets the self's value to an Array containing all passed values" do
-    @cookie.send(:initialize, "test-cookie", "one", "two", "three")
-    @cookie.value.should == ["one", "two", "three"]
-  end
+    it "sets the self's value to an Array containing all passed values" do
+      @cookie.send(:initialize, "test-cookie", "one", "two", "three")
+      @cookie.value.should == ["one", "two", "three"]
+    end
 
-  it "sets self to a non-secure cookie" do
-    @cookie.send(:initialize, "test", "one", "two", "three")
-    @cookie.secure.should be_false
+    it "sets self to a non-secure cookie" do
+      @cookie.send(:initialize, "test", "one", "two", "three")
+      @cookie.secure.should == false
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/name_spec.rb b/spec/ruby/library/cgi/cookie/name_spec.rb
index 14226824c8..4908204e8a 100644
--- a/spec/ruby/library/cgi/cookie/name_spec.rb
+++ b/spec/ruby/library/cgi/cookie/name_spec.rb
@@ -1,23 +1,26 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#name" do
-  it "returns self's name" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.name.should == "test-cookie"
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("name" => "another cookie")
-    cookie.name.should == "another cookie"
+  describe "CGI::Cookie#name" do
+    it "returns self's name" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.name.should == "test-cookie"
+
+      cookie = CGI::Cookie.new("name" => "another-cookie")
+      cookie.name.should == "another-cookie"
+    end
   end
-end
 
-describe "CGI::Cookie#name=" do
-  it "sets self's expiration date" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.name = "another name"
-    cookie.name.should == "another name"
+  describe "CGI::Cookie#name=" do
+    it "sets self's expiration date" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.name = "another-name"
+      cookie.name.should == "another-name"
 
-    cookie.name = "and one more"
-    cookie.name.should == "and one more"
+      cookie.name = "and-one-more"
+      cookie.name.should == "and-one-more"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/parse_spec.rb b/spec/ruby/library/cgi/cookie/parse_spec.rb
index 90d2c3d148..bc505c37ba 100644
--- a/spec/ruby/library/cgi/cookie/parse_spec.rb
+++ b/spec/ruby/library/cgi/cookie/parse_spec.rb
@@ -1,26 +1,29 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie.parse" do
-  it "parses a raw cookie string into a hash of Cookies" do
-    expected = { "test-cookie" => ["one", "two", "three"] }
-    CGI::Cookie.parse("test-cookie=one&two&three").should == expected
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    expected = { "second cookie" => ["three", "four"], "first cookie" => ["one", "two"] }
-    CGI::Cookie.parse("first cookie=one&two;second cookie=three&four").should == expected
-  end
+  describe "CGI::Cookie.parse" do
+    it "parses a raw cookie string into a hash of Cookies" do
+      expected = { "test-cookie" => ["one", "two", "three"] }
+      CGI::Cookie.parse("test-cookie=one&two&three").should == expected
 
-  it "does not use , for cookie separators" do
-    expected = {
-      "first cookie" => ["one", "two"],
-      "second cookie" => ["three", "four,third_cookie=five", "six"]
-    }
-    CGI::Cookie.parse("first cookie=one&two;second cookie=three&four,third_cookie=five&six").should == expected
-  end
+      expected = { "second-cookie" => ["three", "four"], "first-cookie" => ["one", "two"] }
+      CGI::Cookie.parse("first-cookie=one&two;second-cookie=three&four").should == expected
+    end
+
+    it "does not use , for cookie separators" do
+      expected = {
+        "first-cookie" => ["one", "two"],
+        "second-cookie" => ["three", "four,third_cookie=five", "six"]
+      }
+      CGI::Cookie.parse("first-cookie=one&two;second-cookie=three&four,third_cookie=five&six").should == expected
+    end
 
-  it "unescapes the Cookie values" do
-    cookie = "test-cookie=+%21%22%23%24%25%26%27%28%29%2A%2B%2C-.%2F0123456789%3A%3B%3C%3D%3E%3F%40ABCDEFGHIJKLMNOPQRSTUVWXYZ%5B%5C%5D%5E_%60abcdefghijklmnopqrstuvwxyz%7B%7C%7D%7E"
-    expected = { "test-cookie" => [ " !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~" ] }
-    CGI::Cookie.parse(cookie).should == expected
+    it "unescapes the Cookie values" do
+      cookie = "test-cookie=+%21%22%23%24%25%26%27%28%29%2A%2B%2C-.%2F0123456789%3A%3B%3C%3D%3E%3F%40ABCDEFGHIJKLMNOPQRSTUVWXYZ%5B%5C%5D%5E_%60abcdefghijklmnopqrstuvwxyz%7B%7C%7D%7E"
+      expected = { "test-cookie" => [ " !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~" ] }
+      CGI::Cookie.parse(cookie).should == expected
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/path_spec.rb b/spec/ruby/library/cgi/cookie/path_spec.rb
index 8a2f05aa50..13ee5d726b 100644
--- a/spec/ruby/library/cgi/cookie/path_spec.rb
+++ b/spec/ruby/library/cgi/cookie/path_spec.rb
@@ -1,23 +1,26 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#path" do
-  it "returns self's path" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.path.should == ""
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("name" => "test-cookie", "path" => "/some/path/")
-    cookie.path.should == "/some/path/"
+  describe "CGI::Cookie#path" do
+    it "returns self's path" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.path.should == ""
+
+      cookie = CGI::Cookie.new("name" => "test-cookie", "path" => "/some/path/")
+      cookie.path.should == "/some/path/"
+    end
   end
-end
 
-describe "CGI::Cookie#path=" do
-  it "sets self's path" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.path = "/some/path/"
-    cookie.path.should == "/some/path/"
+  describe "CGI::Cookie#path=" do
+    it "sets self's path" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.path = "/some/path/"
+      cookie.path.should == "/some/path/"
 
-    cookie.path = "/another/path/"
-    cookie.path.should == "/another/path/"
+      cookie.path = "/another/path/"
+      cookie.path.should == "/another/path/"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/secure_spec.rb b/spec/ruby/library/cgi/cookie/secure_spec.rb
index 694bc2eeed..233881b173 100644
--- a/spec/ruby/library/cgi/cookie/secure_spec.rb
+++ b/spec/ruby/library/cgi/cookie/secure_spec.rb
@@ -1,70 +1,73 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#secure" do
-  before :each do
-    @cookie = CGI::Cookie.new("test-cookie")
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  it "returns whether self is a secure cookie or not" do
-    @cookie.secure = true
-    @cookie.secure.should be_true
+  describe "CGI::Cookie#secure" do
+    before :each do
+      @cookie = CGI::Cookie.new("test-cookie")
+    end
 
-    @cookie.secure = false
-    @cookie.secure.should be_false
-  end
-end
+    it "returns whether self is a secure cookie or not" do
+      @cookie.secure = true
+      @cookie.secure.should == true
 
-describe "CGI::Cookie#secure= when passed true" do
-  before :each do
-    @cookie = CGI::Cookie.new("test-cookie")
+      @cookie.secure = false
+      @cookie.secure.should == false
+    end
   end
 
-  it "returns true" do
-    (@cookie.secure = true).should be_true
-  end
+  describe "CGI::Cookie#secure= when passed true" do
+    before :each do
+      @cookie = CGI::Cookie.new("test-cookie")
+    end
 
-  it "sets self to a secure cookie" do
-    @cookie.secure = true
-    @cookie.secure.should be_true
-  end
-end
+    it "returns true" do
+      (@cookie.secure = true).should == true
+    end
 
-describe "CGI::Cookie#secure= when passed false" do
-  before :each do
-    @cookie = CGI::Cookie.new("test-cookie")
+    it "sets self to a secure cookie" do
+      @cookie.secure = true
+      @cookie.secure.should == true
+    end
   end
 
-  it "returns false" do
-    (@cookie.secure = false).should be_false
-  end
+  describe "CGI::Cookie#secure= when passed false" do
+    before :each do
+      @cookie = CGI::Cookie.new("test-cookie")
+    end
 
-  it "sets self to a non-secure cookie" do
-    @cookie.secure = false
-    @cookie.secure.should be_false
-  end
-end
+    it "returns false" do
+      (@cookie.secure = false).should == false
+    end
 
-describe "CGI::Cookie#secure= when passed Object" do
-  before :each do
-    @cookie = CGI::Cookie.new("test-cookie")
+    it "sets self to a non-secure cookie" do
+      @cookie.secure = false
+      @cookie.secure.should == false
+    end
   end
 
-  it "does not change self's secure value" do
-    @cookie.secure = false
+  describe "CGI::Cookie#secure= when passed Object" do
+    before :each do
+      @cookie = CGI::Cookie.new("test-cookie")
+    end
+
+    it "does not change self's secure value" do
+      @cookie.secure = false
 
-    @cookie.secure = Object.new
-    @cookie.secure.should be_false
+      @cookie.secure = Object.new
+      @cookie.secure.should == false
 
-    @cookie.secure = "Test"
-    @cookie.secure.should be_false
+      @cookie.secure = "Test"
+      @cookie.secure.should == false
 
-    @cookie.secure = true
+      @cookie.secure = true
 
-    @cookie.secure = Object.new
-    @cookie.secure.should be_true
+      @cookie.secure = Object.new
+      @cookie.secure.should == true
 
-    @cookie.secure = "Test"
-    @cookie.secure.should be_true
+      @cookie.secure = "Test"
+      @cookie.secure.should == true
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/cookie/to_s_spec.rb b/spec/ruby/library/cgi/cookie/to_s_spec.rb
index 978c2d33eb..20d2579f8d 100644
--- a/spec/ruby/library/cgi/cookie/to_s_spec.rb
+++ b/spec/ruby/library/cgi/cookie/to_s_spec.rb
@@ -1,42 +1,36 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#to_s" do
-  it "returns a String representation of self" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.to_s.should == "test-cookie=; path="
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("test-cookie", "value")
-    cookie.to_s.should == "test-cookie=value; path="
+  describe "CGI::Cookie#to_s" do
+    it "returns a String representation of self" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.to_s.should == "test-cookie=; path="
 
-    cookie = CGI::Cookie.new("test-cookie", "one", "two", "three")
-    cookie.to_s.should == "test-cookie=one&two&three; path="
+      cookie = CGI::Cookie.new("test-cookie", "value")
+      cookie.to_s.should == "test-cookie=value; path="
 
-    cookie = CGI::Cookie.new(
-      'name'    => 'test-cookie',
-      'value'   => ["one", "two", "three"],
-      'path'    => 'some/path/',
-      'domain'  => 'example.com',
-      'expires' => Time.at(1196524602),
-      'secure'  => true)
-    cookie.to_s.should == "test-cookie=one&two&three; domain=example.com; path=some/path/; expires=Sat, 01 Dec 2007 15:56:42 GMT; secure"
-  end
+      cookie = CGI::Cookie.new("test-cookie", "one", "two", "three")
+      cookie.to_s.should == "test-cookie=one&two&three; path="
 
-  it "escapes the self's values" do
-    cookie = CGI::Cookie.new("test-cookie", " !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}")
-    cookie.to_s.should == "test-cookie=+%21%22%23%24%25%26%27%28%29%2A%2B%2C-.%2F0123456789%3A%3B%3C%3D%3E%3F%40ABCDEFGHIJKLMNOPQRSTUVWXYZ%5B%5C%5D%5E_%60abcdefghijklmnopqrstuvwxyz%7B%7C%7D; path="
-  end
+      cookie = CGI::Cookie.new(
+        'name'    => 'test-cookie',
+        'value'   => ["one", "two", "three"],
+        'path'    => 'some/path/',
+        'domain'  => 'example.com',
+        'expires' => Time.at(1196524602),
+        'secure'  => true)
+      cookie.to_s.should == "test-cookie=one&two&three; domain=example.com; path=some/path/; expires=Sat, 01 Dec 2007 15:56:42 GMT; secure"
+    end
 
-  ruby_version_is ""..."2.5" do
-    it "escapes tilde" do
-      cookie = CGI::Cookie.new("test-cookie", "~").to_s.should == "test-cookie=%7E; path="
+    it "escapes the self's values" do
+      cookie = CGI::Cookie.new("test-cookie", " !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}")
+      cookie.to_s.should == "test-cookie=+%21%22%23%24%25%26%27%28%29%2A%2B%2C-.%2F0123456789%3A%3B%3C%3D%3E%3F%40ABCDEFGHIJKLMNOPQRSTUVWXYZ%5B%5C%5D%5E_%60abcdefghijklmnopqrstuvwxyz%7B%7C%7D; path="
     end
-  end
 
-  ruby_version_is "2.5" do
     it "does not escape tilde" do
       cookie = CGI::Cookie.new("test-cookie", "~").to_s.should == "test-cookie=~; path="
     end
   end
-
 end
diff --git a/spec/ruby/library/cgi/cookie/value_spec.rb b/spec/ruby/library/cgi/cookie/value_spec.rb
index 1d5da3a3ac..45032edcbf 100644
--- a/spec/ruby/library/cgi/cookie/value_spec.rb
+++ b/spec/ruby/library/cgi/cookie/value_spec.rb
@@ -1,76 +1,79 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::Cookie#value" do
-  it "returns self's value" do
-    cookie = CGI::Cookie.new("test-cookie")
-    cookie.value.should == []
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    cookie = CGI::Cookie.new("test-cookie", "one")
-    cookie.value.should == ["one"]
+  describe "CGI::Cookie#value" do
+    it "returns self's value" do
+      cookie = CGI::Cookie.new("test-cookie")
+      cookie.value.should == []
 
-    cookie = CGI::Cookie.new("test-cookie", "one", "two", "three")
-    cookie.value.should == ["one", "two", "three"]
+      cookie = CGI::Cookie.new("test-cookie", "one")
+      cookie.value.should == ["one"]
 
-    cookie = CGI::Cookie.new("name" => "test-cookie", "value" => ["one", "two", "three"])
-    cookie.value.should == ["one", "two", "three"]
-  end
+      cookie = CGI::Cookie.new("test-cookie", "one", "two", "three")
+      cookie.value.should == ["one", "two", "three"]
 
-  it "is in synch with self" do
-    fail = []
-    [
-      :pop,
-      :shift,
-      [:<<, "Hello"],
-      [:push, "Hello"],
-      [:unshift, "World"],
-      [:replace, ["A", "B"]],
-      [:[]=, 1, "Set"],
-      [:delete, "first"],
-      [:delete_at, 0],
-    ].each do |method, *args|
-      cookie1 = CGI::Cookie.new("test-cookie", "first", "second")
-      cookie2 = CGI::Cookie.new("test-cookie", "first", "second")
-      cookie1.send(method, *args)
-      cookie2.value.send(method, *args)
-      fail << method unless cookie1.value == cookie2.value
+      cookie = CGI::Cookie.new("name" => "test-cookie", "value" => ["one", "two", "three"])
+      cookie.value.should == ["one", "two", "three"]
     end
-    fail.should be_empty
-  end
-end
 
-describe "CGI::Cookie#value=" do
-  before :each do
-    @cookie = CGI::Cookie.new("test-cookie")
+    it "is in synch with self" do
+      fail = []
+      [
+        :pop,
+        :shift,
+        [:<<, "Hello"],
+        [:push, "Hello"],
+        [:unshift, "World"],
+        [:replace, ["A", "B"]],
+        [:[]=, 1, "Set"],
+        [:delete, "first"],
+        [:delete_at, 0],
+      ].each do |method, *args|
+        cookie1 = CGI::Cookie.new("test-cookie", "first", "second")
+        cookie2 = CGI::Cookie.new("test-cookie", "first", "second")
+        cookie1.send(method, *args)
+        cookie2.value.send(method, *args)
+        fail << method unless cookie1.value == cookie2.value
+      end
+      fail.should.empty?
+    end
   end
 
-  it "sets self's value" do
-    @cookie.value = ["one"]
-    @cookie.value.should == ["one"]
+  describe "CGI::Cookie#value=" do
+    before :each do
+      @cookie = CGI::Cookie.new("test-cookie")
+    end
 
-    @cookie.value = ["one", "two", "three"]
-    @cookie.value.should == ["one", "two", "three"]
-  end
+    it "sets self's value" do
+      @cookie.value = ["one"]
+      @cookie.value.should == ["one"]
 
-  it "automatically converts the passed Object to an Array using #Array" do
-    @cookie.value = "test"
-    @cookie.value.should == ["test"]
+      @cookie.value = ["one", "two", "three"]
+      @cookie.value.should == ["one", "two", "three"]
+    end
 
-    obj = mock("to_a")
-    obj.should_receive(:to_a).and_return(["1", "2"])
-    @cookie.value = obj
-    @cookie.value.should == ["1", "2"]
+    it "automatically converts the passed Object to an Array using #Array" do
+      @cookie.value = "test"
+      @cookie.value.should == ["test"]
 
-    obj = mock("to_ary")
-    obj.should_receive(:to_ary).and_return(["1", "2"])
-    @cookie.value = obj
-    @cookie.value.should == ["1", "2"]
-  end
+      obj = mock("to_a")
+      obj.should_receive(:to_a).and_return(["1", "2"])
+      @cookie.value = obj
+      @cookie.value.should == ["1", "2"]
 
-  it "does keep self and the values in sync" do
-    @cookie.value = ["one", "two", "three"]
-    @cookie[0].should == "one"
-    @cookie[1].should == "two"
-    @cookie[2].should == "three"
+      obj = mock("to_ary")
+      obj.should_receive(:to_ary).and_return(["1", "2"])
+      @cookie.value = obj
+      @cookie.value.should == ["1", "2"]
+    end
+
+    it "does keep self and the values in sync" do
+      @cookie.value = ["one", "two", "three"]
+      @cookie[0].should == "one"
+      @cookie[1].should == "two"
+      @cookie[2].should == "three"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/escapeElement_spec.rb b/spec/ruby/library/cgi/escapeElement_spec.rb
index 148926c453..72c38d6028 100644
--- a/spec/ruby/library/cgi/escapeElement_spec.rb
+++ b/spec/ruby/library/cgi/escapeElement_spec.rb
@@ -1,5 +1,11 @@
 require_relative '../../spec_helper'
-require 'cgi'
+
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+end
+ruby_version_is "4.0" do
+  require 'cgi/escape'
+end
 
 describe "CGI.escapeElement when passed String, elements, ..." do
   it "escapes only the tags of the passed elements in the passed String" do
diff --git a/spec/ruby/library/cgi/escapeHTML_spec.rb b/spec/ruby/library/cgi/escapeHTML_spec.rb
index dcbfebe720..6e70e87ed7 100644
--- a/spec/ruby/library/cgi/escapeHTML_spec.rb
+++ b/spec/ruby/library/cgi/escapeHTML_spec.rb
@@ -1,11 +1,19 @@
 require_relative '../../spec_helper'
-require 'cgi'
+begin
+  require 'cgi/escape'
+rescue LoadError
+  require 'cgi'
+end
 
 describe "CGI.escapeHTML" do
   it "escapes special HTML characters (&\"<>') in the passed argument" do
     CGI.escapeHTML(%[& < > " ']).should == '&amp; &lt; &gt; &quot; &#39;'
   end
 
+  it "escapes invalid encoding" do
+    CGI.escapeHTML(%[<\xA4??>]).should == "&lt;\xA4??&gt;"
+  end
+
   it "does not escape any other characters" do
     chars = " !\#$%()*+,-./0123456789:;=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
     CGI.escapeHTML(chars).should == chars
diff --git a/spec/ruby/library/cgi/escapeURIComponent_spec.rb b/spec/ruby/library/cgi/escapeURIComponent_spec.rb
new file mode 100644
index 0000000000..98efa2e67e
--- /dev/null
+++ b/spec/ruby/library/cgi/escapeURIComponent_spec.rb
@@ -0,0 +1,78 @@
+require_relative '../../spec_helper'
+begin
+  require 'cgi/escape'
+rescue LoadError
+  require 'cgi'
+end
+
+describe "CGI.escapeURIComponent" do
+  it "percent-encodes characters reserved according to RFC 3986" do
+    # https://www.rfc-editor.org/rfc/rfc3986#section-2.2
+    string = ":/?#[]@!$&'()*+,;="
+    CGI.escapeURIComponent(string).should == "%3A%2F%3F%23%5B%5D%40%21%24%26%27%28%29%2A%2B%2C%3B%3D"
+  end
+
+  it "does not percent-encode unreserved characters according to RFC 3986" do
+    string = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+    CGI.escapeURIComponent(string).should == "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+  end
+
+  it "encodes % character as %25" do
+    CGI.escapeURIComponent("%").should == "%25"
+  end
+
+  # Compare to .escape which uses "+".
+  it "percent-encodes single whitespace" do
+    CGI.escapeURIComponent(" ").should == "%20"
+  end
+
+  it "percent-encodes all non-reserved and non-unreserved ASCII characters" do
+    special_set = ":/?#[]@!$&'()*+,;=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+    all_other = (0x00..0x7F).filter_map { |i| i.chr unless special_set.include?(i.chr) }.join
+    encoded = CGI.escapeURIComponent(all_other)
+    encoded.should.match?(/\A(?:%[0-9A-F]{2}){#{all_other.length}}\z/)
+  end
+
+  it "percent-encodes non-ASCII bytes" do
+    bytes = (0x80..0xFF).map(&:chr).join
+    encoded = CGI.escapeURIComponent(bytes)
+    encoded.should.match?(/\A(?:%[0-9A-F]{2}){#{bytes.length}}\z/)
+  end
+
+  it "processes multi-byte characters as separate bytes, percent-encoding each one" do
+    CGI.escapeURIComponent("β").should == "%CE%B2" # "β" bytes representation is CE B2
+  end
+
+  it "produces a copy of an empty string" do
+    string = "".encode(Encoding::BINARY)
+    encoded = CGI.escapeURIComponent(string)
+    encoded.should == ""
+    encoded.encoding.should == Encoding::BINARY
+    string.should_not.equal?(encoded)
+  end
+
+  it "preserves string's encoding" do
+    string = "whatever".encode("ASCII-8BIT")
+    CGI.escapeURIComponent(string).encoding.should == Encoding::ASCII_8BIT
+  end
+
+  it "processes even strings with invalid encoding, percent-encoding octets as-is" do
+    string = "\xC0<<".dup.force_encoding("UTF-8")
+    CGI.escapeURIComponent(string).should == "%C0%3C%3C"
+  end
+
+  it "raises a TypeError with nil" do
+    -> {
+      CGI.escapeURIComponent(nil)
+    }.should.raise(TypeError, "no implicit conversion of nil into String")
+  end
+
+  it "uses implicit type conversion to String" do
+    object = Object.new
+    def object.to_str
+      "a b"
+    end
+
+    CGI.escapeURIComponent(object).should == "a%20b"
+  end
+end
diff --git a/spec/ruby/library/cgi/escape_spec.rb b/spec/ruby/library/cgi/escape_spec.rb
index 351bfe1070..55eb0b66c2 100644
--- a/spec/ruby/library/cgi/escape_spec.rb
+++ b/spec/ruby/library/cgi/escape_spec.rb
@@ -1,5 +1,9 @@
 require_relative '../../spec_helper'
-require 'cgi'
+begin
+  require 'cgi/escape'
+rescue LoadError
+  require 'cgi'
+end
 
 describe "CGI.escape" do
   it "url-encodes the passed argument" do
@@ -7,20 +11,12 @@ describe "CGI.escape" do
     expected = "+%21%22%23%24%25%26%27%28%29%2A%2B%2C-.%2F0123456789%3A%3B%3C%3D%3E%3F%40ABCDEFGHIJKLMNOPQRSTUVWXYZ%5B%5C%5D%5E_%60abcdefghijklmnopqrstuvwxyz%7B%7C%7D"
     CGI.escape(input).should == expected
 
-    input = "http://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
-    expected = 'http%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
+    input = "https://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
+    expected = 'https%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
     CGI.escape(input).should == expected
   end
 
-  ruby_version_is ""..."2.5" do
-    it "escapes tilde" do
-      CGI.escape("~").should == "%7E"
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "does not escape tilde" do
-      CGI.escape("~").should == "~"
-    end
+  it "does not escape tilde" do
+    CGI.escape("~").should == "~"
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/a_spec.rb b/spec/ruby/library/cgi/htmlextension/a_spec.rb
index 05b4c2d14c..78d3dec8fa 100644
--- a/spec/ruby/library/cgi/htmlextension/a_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/a_spec.rb
@@ -1,49 +1,52 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#a" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed a String" do
-    it "returns an 'a'-element, using the passed String as the 'href'-attribute" do
-      output = @html.a("http://www.example.com")
-      output.should equal_element("A", "HREF" => "http://www.example.com")
+  describe "CGI::HtmlExtension#a" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "includes the passed block's return value when passed a block" do
-      output = @html.a("http://www.example.com") { "Example" }
-      output.should equal_element("A", { "HREF" => "http://www.example.com" }, "Example")
-    end
-  end
+    describe "when passed a String" do
+      it "returns an 'a'-element, using the passed String as the 'href'-attribute" do
+        output = @html.a("http://www.example.com")
+        output.should equal_element("A", "HREF" => "http://www.example.com")
+      end
 
-  describe "when passed a Hash" do
-    it "returns an 'a'-element, using the passed Hash for attributes" do
-      attributes = {"HREF" => "http://www.example.com", "TARGET" => "_top"}
-      @html.a(attributes).should equal_element("A", attributes)
+      it "includes the passed block's return value when passed a block" do
+        output = @html.a("http://www.example.com") { "Example" }
+        output.should equal_element("A", { "HREF" => "http://www.example.com" }, "Example")
+      end
     end
 
-    it "includes the passed block's return value when passed a block" do
-      attributes = {"HREF" => "http://www.example.com", "TARGET" => "_top"}
-      @html.a(attributes) { "Example" }.should equal_element("A", attributes, "Example")
-    end
-  end
+    describe "when passed a Hash" do
+      it "returns an 'a'-element, using the passed Hash for attributes" do
+        attributes = {"HREF" => "http://www.example.com", "TARGET" => "_top"}
+        @html.a(attributes).should equal_element("A", attributes)
+      end
 
-  describe "when each HTML generation" do
-    it "returns the doctype declaration for HTML3" do
-      CGISpecs.cgi_new("html3").a.should == %(<A HREF=""></A>)
-      CGISpecs.cgi_new("html3").a { "link text" }.should == %(<A HREF="">link text</A>)
+      it "includes the passed block's return value when passed a block" do
+        attributes = {"HREF" => "http://www.example.com", "TARGET" => "_top"}
+        @html.a(attributes) { "Example" }.should equal_element("A", attributes, "Example")
+      end
     end
 
-    it "returns the doctype declaration for HTML4" do
-      CGISpecs.cgi_new("html4").a.should == %(<A HREF=""></A>)
-      CGISpecs.cgi_new("html4").a { "link text" }.should == %(<A HREF="">link text</A>)
-    end
-    it "returns the doctype declaration for the Transitional version of HTML4" do
-      CGISpecs.cgi_new("html4Tr").a.should == %(<A HREF=""></A>)
-      CGISpecs.cgi_new("html4Tr").a { "link text" }.should == %(<A HREF="">link text</A>)
+    describe "when each HTML generation" do
+      it "returns the doctype declaration for HTML3" do
+        CGISpecs.cgi_new("html3").a.should == %(<A HREF=""></A>)
+        CGISpecs.cgi_new("html3").a { "link text" }.should == %(<A HREF="">link text</A>)
+      end
+
+      it "returns the doctype declaration for HTML4" do
+        CGISpecs.cgi_new("html4").a.should == %(<A HREF=""></A>)
+        CGISpecs.cgi_new("html4").a { "link text" }.should == %(<A HREF="">link text</A>)
+      end
+      it "returns the doctype declaration for the Transitional version of HTML4" do
+        CGISpecs.cgi_new("html4Tr").a.should == %(<A HREF=""></A>)
+        CGISpecs.cgi_new("html4Tr").a { "link text" }.should == %(<A HREF="">link text</A>)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/base_spec.rb b/spec/ruby/library/cgi/htmlextension/base_spec.rb
index 877ac321cd..1eedfdea54 100644
--- a/spec/ruby/library/cgi/htmlextension/base_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/base_spec.rb
@@ -1,33 +1,36 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#base" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when bassed a String" do
-    it "returns a 'base'-element, using the passed String as the 'href'-attribute" do
-      output = @html.base("http://www.example.com")
-      output.should equal_element("BASE", {"HREF" => "http://www.example.com"}, nil, not_closed: true)
+  describe "CGI::HtmlExtension#base" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.base("http://www.example.com") { "Example" }
-      output.should equal_element("BASE", {"HREF" => "http://www.example.com"}, nil, not_closed: true)
-    end
-  end
+    describe "when bassed a String" do
+      it "returns a 'base'-element, using the passed String as the 'href'-attribute" do
+        output = @html.base("http://www.example.com")
+        output.should equal_element("BASE", {"HREF" => "http://www.example.com"}, nil, not_closed: true)
+      end
 
-  describe "when passed a Hash" do
-    it "returns a 'base'-element, using the passed Hash for attributes" do
-      output = @html.base("HREF" => "http://www.example.com", "ID" => "test")
-      output.should equal_element("BASE", {"HREF" => "http://www.example.com", "ID" => "test"}, nil, not_closed: true)
+      it "ignores a passed block" do
+        output = @html.base("http://www.example.com") { "Example" }
+        output.should equal_element("BASE", {"HREF" => "http://www.example.com"}, nil, not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.base("HREF" => "http://www.example.com", "ID" => "test") { "Example" }
-      output.should equal_element("BASE", {"HREF" => "http://www.example.com", "ID" => "test"}, nil, not_closed: true)
+    describe "when passed a Hash" do
+      it "returns a 'base'-element, using the passed Hash for attributes" do
+        output = @html.base("HREF" => "http://www.example.com", "ID" => "test")
+        output.should equal_element("BASE", {"HREF" => "http://www.example.com", "ID" => "test"}, nil, not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.base("HREF" => "http://www.example.com", "ID" => "test") { "Example" }
+        output.should equal_element("BASE", {"HREF" => "http://www.example.com", "ID" => "test"}, nil, not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/blockquote_spec.rb b/spec/ruby/library/cgi/htmlextension/blockquote_spec.rb
index a7b833b1c5..883e36f78b 100644
--- a/spec/ruby/library/cgi/htmlextension/blockquote_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/blockquote_spec.rb
@@ -1,33 +1,36 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#blockquote" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed a String" do
-    it "returns a 'blockquote'-element, using the passed String for the 'cite'-attribute" do
-      output = @html.blockquote("http://www.example.com/quotes/foo.html")
-      output.should equal_element("BLOCKQUOTE", "CITE" => "http://www.example.com/quotes/foo.html")
+  describe "CGI::HtmlExtension#blockquote" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "includes the passed block's return value when passed a block" do
-      output = @html.blockquote("http://www.example.com/quotes/foo.html") { "Foo!" }
-      output.should equal_element("BLOCKQUOTE", { "CITE" => "http://www.example.com/quotes/foo.html" }, "Foo!")
-    end
-  end
+    describe "when passed a String" do
+      it "returns a 'blockquote'-element, using the passed String for the 'cite'-attribute" do
+        output = @html.blockquote("http://www.example.com/quotes/foo.html")
+        output.should equal_element("BLOCKQUOTE", "CITE" => "http://www.example.com/quotes/foo.html")
+      end
 
-  describe "when passed a Hash" do
-    it "returns a 'blockquote'-element, using the passed Hash for attributes" do
-      output = @html.blockquote("CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test")
-      output.should equal_element("BLOCKQUOTE", "CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test")
+      it "includes the passed block's return value when passed a block" do
+        output = @html.blockquote("http://www.example.com/quotes/foo.html") { "Foo!" }
+        output.should equal_element("BLOCKQUOTE", { "CITE" => "http://www.example.com/quotes/foo.html" }, "Foo!")
+      end
     end
 
-    it "includes the passed block's return value when passed a block" do
-      output = @html.blockquote("CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test") { "Foo!" }
-      output.should equal_element("BLOCKQUOTE", {"CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test"}, "Foo!")
+    describe "when passed a Hash" do
+      it "returns a 'blockquote'-element, using the passed Hash for attributes" do
+        output = @html.blockquote("CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test")
+        output.should equal_element("BLOCKQUOTE", "CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test")
+      end
+
+      it "includes the passed block's return value when passed a block" do
+        output = @html.blockquote("CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test") { "Foo!" }
+        output.should equal_element("BLOCKQUOTE", {"CITE" => "http://www.example.com/quotes/foo.html", "ID" => "test"}, "Foo!")
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/br_spec.rb b/spec/ruby/library/cgi/htmlextension/br_spec.rb
index dfca121884..23c2cb4a48 100644
--- a/spec/ruby/library/cgi/htmlextension/br_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/br_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#br" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when each HTML generation" do
-    it "returns the doctype declaration for HTML3" do
-      CGISpecs.cgi_new("html3").br.should == "<BR>"
+  describe "CGI::HtmlExtension#br" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "returns the doctype declaration for HTML4" do
-      CGISpecs.cgi_new("html4").br.should == "<BR>"
-    end
-    it "returns the doctype declaration for the Transitional version of HTML4" do
-      CGISpecs.cgi_new("html4Tr").br.should == "<BR>"
+    describe "when each HTML generation" do
+      it "returns the doctype declaration for HTML3" do
+        CGISpecs.cgi_new("html3").br.should == "<BR>"
+      end
+
+      it "returns the doctype declaration for HTML4" do
+        CGISpecs.cgi_new("html4").br.should == "<BR>"
+      end
+      it "returns the doctype declaration for the Transitional version of HTML4" do
+        CGISpecs.cgi_new("html4Tr").br.should == "<BR>"
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/caption_spec.rb b/spec/ruby/library/cgi/htmlextension/caption_spec.rb
index 16615028b8..3d3e21ecaa 100644
--- a/spec/ruby/library/cgi/htmlextension/caption_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/caption_spec.rb
@@ -1,33 +1,36 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#caption" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed a String" do
-    it "returns a 'caption'-element, using the passed String for the 'align'-attribute" do
-      output = @html.caption("left")
-      output.should equal_element("CAPTION", "ALIGN" => "left")
+  describe "CGI::HtmlExtension#caption" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "includes the passed block's return value when passed a block" do
-      output = @html.caption("left") { "Capital Cities" }
-      output.should equal_element("CAPTION", {"ALIGN" => "left"}, "Capital Cities")
-    end
-  end
+    describe "when passed a String" do
+      it "returns a 'caption'-element, using the passed String for the 'align'-attribute" do
+        output = @html.caption("left")
+        output.should equal_element("CAPTION", "ALIGN" => "left")
+      end
 
-  describe "when passed a Hash" do
-    it "returns a 'caption'-element, using the passed Hash for attributes" do
-      output = @html.caption("ALIGN" => "left", "ID" => "test")
-      output.should equal_element("CAPTION", "ALIGN" => "left", "ID" => "test")
+      it "includes the passed block's return value when passed a block" do
+        output = @html.caption("left") { "Capital Cities" }
+        output.should equal_element("CAPTION", {"ALIGN" => "left"}, "Capital Cities")
+      end
     end
 
-    it "includes the passed block's return value when passed a block" do
-      output = @html.caption("ALIGN" => "left", "ID" => "test") { "Capital Cities" }
-      output.should equal_element("CAPTION", {"ALIGN" => "left", "ID" => "test"}, "Capital Cities")
+    describe "when passed a Hash" do
+      it "returns a 'caption'-element, using the passed Hash for attributes" do
+        output = @html.caption("ALIGN" => "left", "ID" => "test")
+        output.should equal_element("CAPTION", "ALIGN" => "left", "ID" => "test")
+      end
+
+      it "includes the passed block's return value when passed a block" do
+        output = @html.caption("ALIGN" => "left", "ID" => "test") { "Capital Cities" }
+        output.should equal_element("CAPTION", {"ALIGN" => "left", "ID" => "test"}, "Capital Cities")
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/checkbox_group_spec.rb b/spec/ruby/library/cgi/htmlextension/checkbox_group_spec.rb
index 64f852cc52..07163c010e 100644
--- a/spec/ruby/library/cgi/htmlextension/checkbox_group_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/checkbox_group_spec.rb
@@ -1,76 +1,79 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#checkbox_group" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed name, values ..." do
-    it "returns a sequence of 'checkbox'-elements with the passed name and the passed values" do
-      output = CGISpecs.split(@html.checkbox_group("test", "foo", "bar", "baz"))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+  describe "CGI::HtmlExtension#checkbox_group" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "allows passing a value inside an Array" do
-      output = CGISpecs.split(@html.checkbox_group("test", ["foo"], "bar", ["baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
-    end
+    describe "when passed name, values ..." do
+      it "returns a sequence of 'checkbox'-elements with the passed name and the passed values" do
+        output = CGISpecs.split(@html.checkbox_group("test", "foo", "bar", "baz"))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
 
-    it "allows passing a value as an Array containing the value and the checked state or a label" do
-      output = CGISpecs.split(@html.checkbox_group("test", ["foo"], ["bar", true], ["baz", "label for baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "label for baz", not_closed: true)
-    end
+      it "allows passing a value inside an Array" do
+        output = CGISpecs.split(@html.checkbox_group("test", ["foo"], "bar", ["baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
 
-    it "allows passing a value as an Array containing the value, a label and the checked state" do
-      output = CGISpecs.split(@html.checkbox_group("test", ["foo", "label for foo", true], ["bar", "label for bar", false], ["baz", "label for baz", true]))
-      output[0].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "label for foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "label for bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "label for baz", not_closed: true)
-    end
+      it "allows passing a value as an Array containing the value and the checked state or a label" do
+        output = CGISpecs.split(@html.checkbox_group("test", ["foo"], ["bar", true], ["baz", "label for baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "label for baz", not_closed: true)
+      end
 
-    it "returns an empty String when passed no values" do
-      @html.checkbox_group("test").should == ""
-    end
+      it "allows passing a value as an Array containing the value, a label and the checked state" do
+        output = CGISpecs.split(@html.checkbox_group("test", ["foo", "label for foo", true], ["bar", "label for bar", false], ["baz", "label for baz", true]))
+        output[0].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "label for foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "label for bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "label for baz", not_closed: true)
+      end
+
+      it "returns an empty String when passed no values" do
+        @html.checkbox_group("test").should == ""
+      end
 
-    it "ignores a passed block" do
-      output = CGISpecs.split(@html.checkbox_group("test", "foo", "bar", "baz") { "test" })
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      it "ignores a passed block" do
+        output = CGISpecs.split(@html.checkbox_group("test", "foo", "bar", "baz") { "test" })
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "uses the passed Hash to generate the checkbox sequence" do
-      output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+    describe "when passed Hash" do
+      it "uses the passed Hash to generate the checkbox sequence" do
+        output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
 
-      output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => [["foo"], ["bar", true], "baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+        output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => [["foo"], ["bar", true], "baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
 
-      output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "1"}, "Foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "checkbox", "VALUE" => "2"}, "Bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "Baz"}, "Baz", not_closed: true)
-    end
+        output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "1"}, "Foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "checkbox", "VALUE" => "2"}, "Bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "Baz"}, "Baz", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]) { "test" })
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      it "ignores a passed block" do
+        output = CGISpecs.split(@html.checkbox_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]) { "test" })
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "checkbox", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/checkbox_spec.rb b/spec/ruby/library/cgi/htmlextension/checkbox_spec.rb
index af76fa1da9..ad87b78061 100644
--- a/spec/ruby/library/cgi/htmlextension/checkbox_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/checkbox_spec.rb
@@ -1,77 +1,80 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#checkbox" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a checkbox-'input'-element without a name" do
-      output = @html.checkbox
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "checkbox"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#checkbox" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.checkbox { "test" }
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "checkbox"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a checkbox-'input'-element without a name" do
+        output = @html.checkbox
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "checkbox"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns a checkbox-'input'-element with the passed name" do
-      output = @html.checkbox("test")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.checkbox { "test" }
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "checkbox"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.checkbox("test") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns a checkbox-'input'-element with the passed name" do
+        output = @html.checkbox("test")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox"}, "", not_closed: true)
+      end
 
-  describe "CGI::HtmlExtension#checkbox when passed name, value" do
-    it "returns a checkbox-'input'-element with the passed name and value" do
-      output = @html.checkbox("test", "test-value")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.checkbox("test") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.checkbox("test", "test-value") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+    describe "CGI::HtmlExtension#checkbox when passed name, value" do
+      it "returns a checkbox-'input'-element with the passed name and value" do
+        output = @html.checkbox("test", "test-value")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.checkbox("test", "test-value") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed name, value, checked" do
-    it "returns a checked checkbox-'input'-element with the passed name and value when checked is true" do
-      output = @html.checkbox("test", "test-value", true)
-      output.should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+    describe "when passed name, value, checked" do
+      it "returns a checked checkbox-'input'-element with the passed name and value when checked is true" do
+        output = @html.checkbox("test", "test-value", true)
+        output.should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
 
-      output = @html.checkbox("test", "test-value", false)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+        output = @html.checkbox("test", "test-value", false)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
 
-      output = @html.checkbox("test", "test-value", nil)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
-    end
+        output = @html.checkbox("test", "test-value", nil)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = @html.checkbox("test", "test-value", nil) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.checkbox("test", "test-value", nil) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "checkbox", "VALUE" => "test-value"}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "returns a checkbox-'input'-element using the passed Hash for attributes" do
-      attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
-      output = @html.checkbox(attributes)
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
-    end
+    describe "when passed Hash" do
+      it "returns a checkbox-'input'-element using the passed Hash for attributes" do
+        attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
+        output = @html.checkbox(attributes)
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
-      output = @html.checkbox(attributes) { "test" }
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
+      it "ignores a passed block" do
+        attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
+        output = @html.checkbox(attributes) { "test" }
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/doctype_spec.rb b/spec/ruby/library/cgi/htmlextension/doctype_spec.rb
index 9a28a8883b..02af831855 100644
--- a/spec/ruby/library/cgi/htmlextension/doctype_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/doctype_spec.rb
@@ -1,27 +1,30 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#doctype" do
-  describe "when each HTML generation" do
-    it "returns the doctype declaration for HTML3" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">'
-      CGISpecs.cgi_new("html3").doctype.should == expect
-    end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-    it "returns the doctype declaration for HTML4" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">'
-      CGISpecs.cgi_new("html4").doctype.should == expect
-    end
+  describe "CGI::HtmlExtension#doctype" do
+    describe "when each HTML generation" do
+      it "returns the doctype declaration for HTML3" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">'
+        CGISpecs.cgi_new("html3").doctype.should == expect
+      end
 
-    it "returns the doctype declaration for the Frameset version of HTML4" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">'
-      CGISpecs.cgi_new("html4Fr").doctype.should == expect
-    end
+      it "returns the doctype declaration for HTML4" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">'
+        CGISpecs.cgi_new("html4").doctype.should == expect
+      end
+
+      it "returns the doctype declaration for the Frameset version of HTML4" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">'
+        CGISpecs.cgi_new("html4Fr").doctype.should == expect
+      end
 
-    it "returns the doctype declaration for the Transitional version of HTML4" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">'
-      CGISpecs.cgi_new("html4Tr").doctype.should == expect
+      it "returns the doctype declaration for the Transitional version of HTML4" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">'
+        CGISpecs.cgi_new("html4Tr").doctype.should == expect
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/file_field_spec.rb b/spec/ruby/library/cgi/htmlextension/file_field_spec.rb
index 2a0632fd58..eff077b9a2 100644
--- a/spec/ruby/library/cgi/htmlextension/file_field_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/file_field_spec.rb
@@ -1,72 +1,75 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#file_field" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a file-'input'-element without a name and a size of 20" do
-      output = @html.file_field
-      output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "", "TYPE" => "file"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#file_field" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.file_field { "test" }
-      output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "", "TYPE" => "file"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a file-'input'-element without a name and a size of 20" do
+        output = @html.file_field
+        output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "", "TYPE" => "file"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns a checkbox-'input'-element with the passed name" do
-      output = @html.file_field("Example")
-      output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.file_field { "test" }
+        output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "", "TYPE" => "file"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.file_field("Example") { "test" }
-      output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns a checkbox-'input'-element with the passed name" do
+        output = @html.file_field("Example")
+        output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      end
 
-  describe "when passed name, size" do
-    it "returns a checkbox-'input'-element with the passed name and size" do
-      output = @html.file_field("Example", 40)
-      output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.file_field("Example") { "test" }
+        output.should equal_element("INPUT", {"SIZE" => 20, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.file_field("Example", 40) { "test" }
-      output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, size" do
+      it "returns a checkbox-'input'-element with the passed name and size" do
+        output = @html.file_field("Example", 40)
+        output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      end
 
-  describe "when passed name, size, maxlength" do
-    it "returns a checkbox-'input'-element with the passed name, size and maxlength" do
-      output = @html.file_field("Example", 40, 100)
-      output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file", "MAXLENGTH" => 100}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.file_field("Example", 40) { "test" }
+        output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.file_field("Example", 40, 100) { "test" }
-      output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file", "MAXLENGTH" => 100}, "", not_closed: true)
+    describe "when passed name, size, maxlength" do
+      it "returns a checkbox-'input'-element with the passed name, size and maxlength" do
+        output = @html.file_field("Example", 40, 100)
+        output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file", "MAXLENGTH" => 100}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.file_field("Example", 40, 100) { "test" }
+        output.should equal_element("INPUT", {"SIZE" => 40, "NAME" => "Example", "TYPE" => "file", "MAXLENGTH" => 100}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed a Hash" do
-    it "returns a file-'input'-element using the passed Hash for attributes" do
-      output = @html.file_field("NAME" => "test", "SIZE" => 40)
-      output.should equal_element("INPUT", {"NAME" => "test", "SIZE" => 40}, "", not_closed: true)
+    describe "when passed a Hash" do
+      it "returns a file-'input'-element using the passed Hash for attributes" do
+        output = @html.file_field("NAME" => "test", "SIZE" => 40)
+        output.should equal_element("INPUT", {"NAME" => "test", "SIZE" => 40}, "", not_closed: true)
 
-      output = @html.file_field("NAME" => "test", "MAXLENGTH" => 100)
-      output.should equal_element("INPUT", {"NAME" => "test", "MAXLENGTH" => 100}, "", not_closed: true)
-    end
+        output = @html.file_field("NAME" => "test", "MAXLENGTH" => 100)
+        output.should equal_element("INPUT", {"NAME" => "test", "MAXLENGTH" => 100}, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = @html.file_field("NAME" => "test", "SIZE" => 40) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "SIZE" => 40}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.file_field("NAME" => "test", "SIZE" => 40) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "SIZE" => 40}, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/form_spec.rb b/spec/ruby/library/cgi/htmlextension/form_spec.rb
index 8c0ac97735..55ac63152b 100644
--- a/spec/ruby/library/cgi/htmlextension/form_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/form_spec.rb
@@ -1,58 +1,61 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#form" do
-  before :each do
-    @html = CGISpecs.cgi_new
-    @html.stub!(:script_name).and_return("/path/to/some/script")
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a 'form'-element" do
-      output = @html.form
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/path/to/some/script"}, "")
+  describe "CGI::HtmlExtension#form" do
+    before :each do
+      @html = CGISpecs.cgi_new
+      @html.stub!(:script_name).and_return("/path/to/some/script")
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.form { "test" }
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/path/to/some/script"}, "test")
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a 'form'-element" do
+        output = @html.form
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/path/to/some/script"}, "")
+      end
 
-  describe "when passed method" do
-    it "returns a 'form'-element with the passed method" do
-      output = @html.form("get")
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/path/to/some/script"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.form { "test" }
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/path/to/some/script"}, "test")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.form("get") { "test" }
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/path/to/some/script"}, "test")
-    end
-  end
+    describe "when passed method" do
+      it "returns a 'form'-element with the passed method" do
+        output = @html.form("get")
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/path/to/some/script"}, "")
+      end
 
-  describe "when passed method, action" do
-    it "returns a 'form'-element with the passed method and the passed action" do
-      output = @html.form("get", "/some/other/script")
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/some/other/script"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.form("get") { "test" }
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/path/to/some/script"}, "test")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.form("get", "/some/other/script") { "test" }
-      output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/some/other/script"}, "test")
-    end
-  end
+    describe "when passed method, action" do
+      it "returns a 'form'-element with the passed method and the passed action" do
+        output = @html.form("get", "/some/other/script")
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/some/other/script"}, "")
+      end
 
-  describe "when passed method, action, enctype" do
-    it "returns a 'form'-element with the passed method, action and enctype" do
-      output = @html.form("get", "/some/other/script", "multipart/form-data")
-      output.should equal_element("FORM", {"ENCTYPE" => "multipart/form-data", "METHOD" => "get", "ACTION" => "/some/other/script"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.form("get", "/some/other/script") { "test" }
+        output.should equal_element("FORM", {"ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ACTION" => "/some/other/script"}, "test")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.form("get", "/some/other/script", "multipart/form-data") { "test" }
-      output.should equal_element("FORM", {"ENCTYPE" => "multipart/form-data", "METHOD" => "get", "ACTION" => "/some/other/script"}, "test")
+    describe "when passed method, action, enctype" do
+      it "returns a 'form'-element with the passed method, action and enctype" do
+        output = @html.form("get", "/some/other/script", "multipart/form-data")
+        output.should equal_element("FORM", {"ENCTYPE" => "multipart/form-data", "METHOD" => "get", "ACTION" => "/some/other/script"}, "")
+      end
+
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.form("get", "/some/other/script", "multipart/form-data") { "test" }
+        output.should equal_element("FORM", {"ENCTYPE" => "multipart/form-data", "METHOD" => "get", "ACTION" => "/some/other/script"}, "test")
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/frame_spec.rb b/spec/ruby/library/cgi/htmlextension/frame_spec.rb
index 2ddd4e1ef0..fef40849eb 100644
--- a/spec/ruby/library/cgi/htmlextension/frame_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/frame_spec.rb
@@ -1,14 +1,17 @@
 require_relative '../../../spec_helper'
-require_relative 'fixtures/common'
-require 'cgi'
 
-describe "CGI::HtmlExtension#frame" do
-  before :each do
-    @html = CGISpecs.cgi_new("html4Fr")
-  end
+ruby_version_is ""..."4.0" do
+  require_relative 'fixtures/common'
+  require 'cgi'
+
+  describe "CGI::HtmlExtension#frame" do
+    before :each do
+      @html = CGISpecs.cgi_new("html4Fr")
+    end
 
-  it "initializes the HTML Generation methods for the Frameset version of HTML4" do
-    @html.frameset.should == "<FRAMESET></FRAMESET>"
-    @html.frameset { "link text" }.should == "<FRAMESET>link text</FRAMESET>"
+    it "initializes the HTML Generation methods for the Frameset version of HTML4" do
+      @html.frameset.should == "<FRAMESET></FRAMESET>"
+      @html.frameset { "link text" }.should == "<FRAMESET>link text</FRAMESET>"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/frameset_spec.rb b/spec/ruby/library/cgi/htmlextension/frameset_spec.rb
index baeb446593..3ad0a9c4d2 100644
--- a/spec/ruby/library/cgi/htmlextension/frameset_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/frameset_spec.rb
@@ -1,14 +1,17 @@
 require_relative '../../../spec_helper'
-require_relative 'fixtures/common'
-require 'cgi'
 
-describe "CGI::HtmlExtension#frameset" do
-  before :each do
-    @html = CGISpecs.cgi_new("html4Fr")
-  end
+ruby_version_is ""..."4.0" do
+  require_relative 'fixtures/common'
+  require 'cgi'
+
+  describe "CGI::HtmlExtension#frameset" do
+    before :each do
+      @html = CGISpecs.cgi_new("html4Fr")
+    end
 
-  it "initializes the HTML Generation methods for the Frameset version of HTML4" do
-    @html.frameset.should == "<FRAMESET></FRAMESET>"
-    @html.frameset { "link text" }.should == "<FRAMESET>link text</FRAMESET>"
+    it "initializes the HTML Generation methods for the Frameset version of HTML4" do
+      @html.frameset.should == "<FRAMESET></FRAMESET>"
+      @html.frameset { "link text" }.should == "<FRAMESET>link text</FRAMESET>"
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/hidden_spec.rb b/spec/ruby/library/cgi/htmlextension/hidden_spec.rb
index 52ebd8c261..b2323775f6 100644
--- a/spec/ruby/library/cgi/htmlextension/hidden_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/hidden_spec.rb
@@ -1,59 +1,62 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#hidden" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an hidden-'input'-element without a name" do
-      output = @html.hidden
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "hidden"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#hidden" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.hidden { "test" }
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "hidden"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an hidden-'input'-element without a name" do
+        output = @html.hidden
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "hidden"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns an hidden-'input'-element with the passed name" do
-      output = @html.hidden("test")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.hidden { "test" }
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "hidden"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.hidden("test") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns an hidden-'input'-element with the passed name" do
+        output = @html.hidden("test")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value" do
-    it "returns an hidden-'input'-element with the passed name and value" do
-      output = @html.hidden("test", "some value")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden", "VALUE" => "some value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.hidden("test") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.hidden("test", "some value") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden", "VALUE" => "some value"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, value" do
+      it "returns an hidden-'input'-element with the passed name and value" do
+        output = @html.hidden("test", "some value")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden", "VALUE" => "some value"}, "", not_closed: true)
+      end
 
-  describe "when passed Hash" do
-    it "returns a checkbox-'input'-element using the passed Hash for attributes" do
-      attributes = { "NAME" => "test", "VALUE" => "some value" }
-      output = @html.hidden("test", "some value")
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.hidden("test", "some value") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "hidden", "VALUE" => "some value"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      attributes = { "NAME" => "test", "VALUE" => "some value" }
-      output = @html.hidden("test", "some value") { "test" }
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a checkbox-'input'-element using the passed Hash for attributes" do
+        attributes = { "NAME" => "test", "VALUE" => "some value" }
+        output = @html.hidden("test", "some value")
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        attributes = { "NAME" => "test", "VALUE" => "some value" }
+        output = @html.hidden("test", "some value") { "test" }
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/html_spec.rb b/spec/ruby/library/cgi/htmlextension/html_spec.rb
index 5d89c82086..60a10fb6b4 100644
--- a/spec/ruby/library/cgi/htmlextension/html_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/html_spec.rb
@@ -1,66 +1,69 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#html" do
-  before :each do
-    @html = CGISpecs.cgi_new
-    @html.stub!(:doctype).and_return("<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>")
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a self's doctype and an 'html'-element" do
-      expected = '<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE><HTML>'
-      @html.html.should == expected
+  describe "CGI::HtmlExtension#html" do
+    before :each do
+      @html = CGISpecs.cgi_new
+      @html.stub!(:doctype).and_return("<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>")
     end
 
-    it "includes the passed block when passed a block" do
-      expected = '<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE><HTML>test</HTML>'
-      @html.html { "test" }.should == expected
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a self's doctype and an 'html'-element" do
+        expected = '<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE><HTML>'
+        @html.html.should == expected
+      end
 
-  describe "when passed 'PRETTY'" do
-    it "returns pretty output when the passed String is 'PRETTY" do
-      expected = "<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>\n<HTML>\n"
-      @html.html("PRETTY").should == expected
+      it "includes the passed block when passed a block" do
+        expected = '<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE><HTML>test</HTML>'
+        @html.html { "test" }.should == expected
+      end
     end
 
-    it "includes the passed block when passed a block" do
-      expected = "<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>\n<HTML>\n  test\n</HTML>\n"
-      @html.html("PRETTY") { "test" }.should == expected
-    end
-  end
+    describe "when passed 'PRETTY'" do
+      it "returns pretty output when the passed String is 'PRETTY" do
+        expected = "<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>\n<HTML>\n"
+        @html.html("PRETTY").should == expected
+      end
 
-  describe "when passed a Hash" do
-    it "returns an 'html'-element using the passed Hash for attributes" do
-      expected = '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"><HTML BLA="TEST">'
-      @html.html("DOCTYPE" => '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">', "BLA" => "TEST").should == expected
+      it "includes the passed block when passed a block" do
+        expected = "<!DOCTYPE SUPA-FUNKAY-RUBYSPEC-DOCTYPE>\n<HTML>\n  test\n</HTML>\n"
+        @html.html("PRETTY") { "test" }.should == expected
+      end
     end
 
-    it "omits the doctype when the Hash contains a 'DOCTYPE' entry that's false or nil" do
-      @html.html("DOCTYPE" => false).should == "<HTML>"
-      @html.html("DOCTYPE" => nil).should == "<HTML>"
-    end
-  end
+    describe "when passed a Hash" do
+      it "returns an 'html'-element using the passed Hash for attributes" do
+        expected = '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"><HTML BLA="TEST">'
+        @html.html("DOCTYPE" => '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">', "BLA" => "TEST").should == expected
+      end
 
-  describe "when each HTML generation" do
-    it "returns the doctype declaration for HTML3" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">'
-      CGISpecs.cgi_new("html3").html.should == expect + "<HTML>"
-      CGISpecs.cgi_new("html3").html { "html body" }.should == expect + "<HTML>html body</HTML>"
+      it "omits the doctype when the Hash contains a 'DOCTYPE' entry that's false or nil" do
+        @html.html("DOCTYPE" => false).should == "<HTML>"
+        @html.html("DOCTYPE" => nil).should == "<HTML>"
+      end
     end
 
-    it "returns the doctype declaration for HTML4" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">'
-      CGISpecs.cgi_new("html4").html.should == expect + "<HTML>"
-      CGISpecs.cgi_new("html4").html { "html body" }.should == expect + "<HTML>html body</HTML>"
-    end
+    describe "when each HTML generation" do
+      it "returns the doctype declaration for HTML3" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">'
+        CGISpecs.cgi_new("html3").html.should == expect + "<HTML>"
+        CGISpecs.cgi_new("html3").html { "html body" }.should == expect + "<HTML>html body</HTML>"
+      end
+
+      it "returns the doctype declaration for HTML4" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">'
+        CGISpecs.cgi_new("html4").html.should == expect + "<HTML>"
+        CGISpecs.cgi_new("html4").html { "html body" }.should == expect + "<HTML>html body</HTML>"
+      end
 
-    it "returns the doctype declaration for the Transitional version of HTML4" do
-      expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">'
-      CGISpecs.cgi_new("html4Tr").html.should == expect + "<HTML>"
-      CGISpecs.cgi_new("html4Tr").html { "html body" }.should == expect + "<HTML>html body</HTML>"
+      it "returns the doctype declaration for the Transitional version of HTML4" do
+        expect = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">'
+        CGISpecs.cgi_new("html4Tr").html.should == expect + "<HTML>"
+        CGISpecs.cgi_new("html4Tr").html { "html body" }.should == expect + "<HTML>html body</HTML>"
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/image_button_spec.rb b/spec/ruby/library/cgi/htmlextension/image_button_spec.rb
index d14bec9ca3..f8770119d4 100644
--- a/spec/ruby/library/cgi/htmlextension/image_button_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/image_button_spec.rb
@@ -1,69 +1,72 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#image_button" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an image-'input'-element without a source image" do
-      output = @html.image_button
-      output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#image_button" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.image_button { "test" }
-      output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an image-'input'-element without a source image" do
+        output = @html.image_button
+        output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image"}, "", not_closed: true)
+      end
 
-  describe "when passed src" do
-    it "returns an image-'input'-element with the passed src" do
-      output = @html.image_button("/path/to/image.png")
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.image_button { "test" }
+        output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.image_button("/path/to/image.png") { "test" }
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image"}, "", not_closed: true)
-    end
-  end
+    describe "when passed src" do
+      it "returns an image-'input'-element with the passed src" do
+        output = @html.image_button("/path/to/image.png")
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image"}, "", not_closed: true)
+      end
 
-  describe "when passed src, name" do
-    it "returns an image-'input'-element with the passed src and name" do
-      output = @html.image_button("/path/to/image.png", "test")
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.image_button("/path/to/image.png") { "test" }
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.image_button("/path/to/image.png", "test") { "test" }
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test"}, "", not_closed: true)
-    end
-  end
+    describe "when passed src, name" do
+      it "returns an image-'input'-element with the passed src and name" do
+        output = @html.image_button("/path/to/image.png", "test")
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test"}, "", not_closed: true)
+      end
 
-  describe "when passed src, name, alt" do
-    it "returns an image-'input'-element with the passed src, name and alt" do
-      output = @html.image_button("/path/to/image.png", "test", "alternative")
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test", "ALT" => "alternative"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.image_button("/path/to/image.png", "test") { "test" }
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.image_button("/path/to/image.png", "test", "alternative") { "test" }
-      output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test", "ALT" => "alternative"}, "", not_closed: true)
-    end
-  end
+    describe "when passed src, name, alt" do
+      it "returns an image-'input'-element with the passed src, name and alt" do
+        output = @html.image_button("/path/to/image.png", "test", "alternative")
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test", "ALT" => "alternative"}, "", not_closed: true)
+      end
 
-  describe "when passed Hash" do
-    it "returns a image-'input'-element using the passed Hash for attributes" do
-      output = @html.image_button("NAME" => "test", "VALUE" => "test-value")
-      output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image", "NAME" => "test", "VALUE" => "test-value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.image_button("/path/to/image.png", "test", "alternative") { "test" }
+        output.should equal_element("INPUT", {"SRC" => "/path/to/image.png", "TYPE" => "image", "NAME" => "test", "ALT" => "alternative"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.image_button("NAME" => "test", "VALUE" => "test-value") { "test" }
-      output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image", "NAME" => "test", "VALUE" => "test-value"}, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a image-'input'-element using the passed Hash for attributes" do
+        output = @html.image_button("NAME" => "test", "VALUE" => "test-value")
+        output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image", "NAME" => "test", "VALUE" => "test-value"}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.image_button("NAME" => "test", "VALUE" => "test-value") { "test" }
+        output.should equal_element("INPUT", {"SRC" => "", "TYPE" => "image", "NAME" => "test", "VALUE" => "test-value"}, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/img_spec.rb b/spec/ruby/library/cgi/htmlextension/img_spec.rb
index 994ae7fedf..a05cfdea48 100644
--- a/spec/ruby/library/cgi/htmlextension/img_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/img_spec.rb
@@ -1,83 +1,86 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#img" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an 'img'-element without an src-url or alt-text" do
-      output = @html.img
-      output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
+  describe "CGI::HtmlExtension#img" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.img { "test" }
-      output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an 'img'-element without an src-url or alt-text" do
+        output = @html.img
+        output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
+      end
 
-  describe "when passed src" do
-    it "returns an 'img'-element with the passed src-url" do
-      output = @html.img("/path/to/some/image.png")
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.img { "test" }
+        output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.img("/path/to/some/image.png")
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "" }, "", not_closed: true)
-    end
-  end
+    describe "when passed src" do
+      it "returns an 'img'-element with the passed src-url" do
+        output = @html.img("/path/to/some/image.png")
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "" }, "", not_closed: true)
+      end
 
-  describe "when passed src, alt" do
-    it "returns an 'img'-element with the passed src-url and the passed alt-text" do
-      output = @html.img("/path/to/some/image.png", "Alternative")
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.img("/path/to/some/image.png")
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "" }, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.img("/path/to/some/image.png", "Alternative") { "test" }
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative" }, "", not_closed: true)
-    end
-  end
+    describe "when passed src, alt" do
+      it "returns an 'img'-element with the passed src-url and the passed alt-text" do
+        output = @html.img("/path/to/some/image.png", "Alternative")
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative" }, "", not_closed: true)
+      end
 
-  describe "when passed src, alt, width" do
-    it "returns an 'img'-element with the passed src-url, the passed alt-text and the passed width" do
-      output = @html.img("/path/to/some/image.png", "Alternative", 40)
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.img("/path/to/some/image.png", "Alternative") { "test" }
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative" }, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.img("/path/to/some/image.png", "Alternative", 40) { "test" }
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40" }, "", not_closed: true)
-    end
-  end
+    describe "when passed src, alt, width" do
+      it "returns an 'img'-element with the passed src-url, the passed alt-text and the passed width" do
+        output = @html.img("/path/to/some/image.png", "Alternative", 40)
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40" }, "", not_closed: true)
+      end
 
-  describe "when passed src, alt, width, height" do
-    it "returns an 'img'-element with the passed src-url, the passed alt-text, the passed width and the passed height" do
-      output = @html.img("/path/to/some/image.png", "Alternative", 40, 60)
-      output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40", "HEIGHT" => "60" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.img("/path/to/some/image.png", "Alternative", 40) { "test" }
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40" }, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.img { "test" }
-      output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
-    end
-  end
+    describe "when passed src, alt, width, height" do
+      it "returns an 'img'-element with the passed src-url, the passed alt-text, the passed width and the passed height" do
+        output = @html.img("/path/to/some/image.png", "Alternative", 40, 60)
+        output.should equal_element("IMG", { "SRC" => "/path/to/some/image.png", "ALT" => "Alternative", "WIDTH" => "40", "HEIGHT" => "60" }, "", not_closed: true)
+      end
 
-  describe "when passed Hash" do
-    it "returns an 'img'-element with the passed Hash as attributes" do
-      attributes = { "SRC" => "src", "ALT" => "alt", "WIDTH" => 100, "HEIGHT" => 50 }
-      output = @html.img(attributes)
-      output.should equal_element("IMG", attributes, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.img { "test" }
+        output.should equal_element("IMG", { "SRC" => "", "ALT" => "" }, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      attributes = { "SRC" => "src", "ALT" => "alt", "WIDTH" => 100, "HEIGHT" => 50 }
-      output = @html.img(attributes) { "test" }
-      output.should equal_element("IMG", attributes, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns an 'img'-element with the passed Hash as attributes" do
+        attributes = { "SRC" => "src", "ALT" => "alt", "WIDTH" => 100, "HEIGHT" => 50 }
+        output = @html.img(attributes)
+        output.should equal_element("IMG", attributes, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        attributes = { "SRC" => "src", "ALT" => "alt", "WIDTH" => 100, "HEIGHT" => 50 }
+        output = @html.img(attributes) { "test" }
+        output.should equal_element("IMG", attributes, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/multipart_form_spec.rb b/spec/ruby/library/cgi/htmlextension/multipart_form_spec.rb
index 0bf2042a33..4b56a7abfe 100644
--- a/spec/ruby/library/cgi/htmlextension/multipart_form_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/multipart_form_spec.rb
@@ -1,64 +1,67 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#multipart_form" do
-  before :each do
-    @html = CGISpecs.cgi_new
-    @html.stub!(:script_name).and_return("/path/to/some/script.rb")
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a 'form'-element with it's enctype set to multipart" do
-      output = @html.multipart_form
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post" }, "")
+  describe "CGI::HtmlExtension#multipart_form" do
+    before :each do
+      @html = CGISpecs.cgi_new
+      @html.stub!(:script_name).and_return("/path/to/some/script.rb")
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.multipart_form { "test" }
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post" }, "test")
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a 'form'-element with its enctype set to multipart" do
+        output = @html.multipart_form
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post" }, "")
+      end
 
-  describe "when passed action" do
-    it "returns a 'form'-element with the passed action" do
-      output = @html.multipart_form("/some/other/script.rb")
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.multipart_form { "test" }
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post" }, "test")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.multipart_form("/some/other/script.rb") { "test" }
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "test")
-    end
-  end
+    describe "when passed action" do
+      it "returns a 'form'-element with the passed action" do
+        output = @html.multipart_form("/some/other/script.rb")
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "")
+      end
 
-  describe "when passed action, enctype" do
-    it "returns a 'form'-element with the passed action and enctype" do
-      output = @html.multipart_form("/some/other/script.rb", "application/x-www-form-urlencoded")
-      output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.multipart_form("/some/other/script.rb") { "test" }
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "test")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.multipart_form("/some/other/script.rb", "application/x-www-form-urlencoded") { "test" }
-      output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "test")
+    describe "when passed action, enctype" do
+      it "returns a 'form'-element with the passed action and enctype" do
+        output = @html.multipart_form("/some/other/script.rb", "application/x-www-form-urlencoded")
+        output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "")
+      end
+
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.multipart_form("/some/other/script.rb", "application/x-www-form-urlencoded") { "test" }
+        output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "post", "ACTION" => "/some/other/script.rb" }, "test")
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "returns a 'form'-element with the passed Hash as attributes" do
-      output = @html.multipart_form("ID" => "test")
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ID" => "test" }, "")
+    describe "when passed Hash" do
+      it "returns a 'form'-element with the passed Hash as attributes" do
+        output = @html.multipart_form("ID" => "test")
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ID" => "test" }, "")
 
-      output = @html.multipart_form("ID" => "test", "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get")
-      output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ID" => "test" }, "")
-    end
+        output = @html.multipart_form("ID" => "test", "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get")
+        output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ID" => "test" }, "")
+      end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.multipart_form("ID" => "test") { "test" }
-      output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ID" => "test" }, "test")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.multipart_form("ID" => "test") { "test" }
+        output.should equal_element("FORM", { "ENCTYPE" => "multipart/form-data", "METHOD" => "post", "ID" => "test" }, "test")
 
-      output = @html.multipart_form("ID" => "test", "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get") { "test" }
-      output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ID" => "test" }, "test")
+        output = @html.multipart_form("ID" => "test", "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get") { "test" }
+        output.should equal_element("FORM", { "ENCTYPE" => "application/x-www-form-urlencoded", "METHOD" => "get", "ID" => "test" }, "test")
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/password_field_spec.rb b/spec/ruby/library/cgi/htmlextension/password_field_spec.rb
index 683bc428ba..0fefdd5c45 100644
--- a/spec/ruby/library/cgi/htmlextension/password_field_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/password_field_spec.rb
@@ -1,84 +1,87 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#password_field" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an password-'input'-element without a name" do
-      output = @html.password_field
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#password_field" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.password_field { "test" }
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an password-'input'-element without a name" do
+        output = @html.password_field
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns an password-'input'-element with the passed name" do
-      output = @html.password_field("test")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.password_field { "test" }
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.password_field("test") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns an password-'input'-element with the passed name" do
+        output = @html.password_field("test")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value" do
-    it "returns an password-'input'-element with the passed name and value" do
-      output = @html.password_field("test", "some value")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.password_field("test") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.password_field("test", "some value") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, value" do
+      it "returns an password-'input'-element with the passed name and value" do
+        output = @html.password_field("test", "some value")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value, size" do
-    it "returns an password-'input'-element with the passed name, value and size" do
-      output = @html.password_field("test", "some value", 60)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.password_field("test", "some value") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.password_field("test", "some value", 60) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, value, size" do
+      it "returns an password-'input'-element with the passed name, value and size" do
+        output = @html.password_field("test", "some value", 60)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value, size, maxlength" do
-    it "returns an password-'input'-element with the passed name, value, size and maxlength" do
-      output = @html.password_field("test", "some value", 60, 12)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.password_field("test", "some value", 60) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.password_field("test", "some value", 60, 12) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+    describe "when passed name, value, size, maxlength" do
+      it "returns an password-'input'-element with the passed name, value, size and maxlength" do
+        output = @html.password_field("test", "some value", 60, 12)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.password_field("test", "some value", 60, 12) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "password", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "returns a checkbox-'input'-element using the passed Hash for attributes" do
-      output = @html.password_field("NAME" => "test", "VALUE" => "some value")
-      output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "password" }, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a checkbox-'input'-element using the passed Hash for attributes" do
+        output = @html.password_field("NAME" => "test", "VALUE" => "some value")
+        output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "password" }, "", not_closed: true)
 
-      output = @html.password_field("TYPE" => "hidden")
-      output.should equal_element("INPUT", {"TYPE" => "password"}, "", not_closed: true)
-    end
+        output = @html.password_field("TYPE" => "hidden")
+        output.should equal_element("INPUT", {"TYPE" => "password"}, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = @html.password_field("NAME" => "test", "VALUE" => "some value") { "test" }
-      output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "password" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.password_field("NAME" => "test", "VALUE" => "some value") { "test" }
+        output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "password" }, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/popup_menu_spec.rb b/spec/ruby/library/cgi/htmlextension/popup_menu_spec.rb
index 3462be09b0..7452d15317 100644
--- a/spec/ruby/library/cgi/htmlextension/popup_menu_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/popup_menu_spec.rb
@@ -1,8 +1,11 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
-require_relative 'shared/popup_menu'
 
-describe "CGI::HtmlExtension#popup_menu" do
-  it_behaves_like :cgi_htmlextension_popup_menu, :popup_menu
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
+  require_relative 'shared/popup_menu'
+
+  describe "CGI::HtmlExtension#popup_menu" do
+    it_behaves_like :cgi_htmlextension_popup_menu, :popup_menu
+  end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/radio_button_spec.rb b/spec/ruby/library/cgi/htmlextension/radio_button_spec.rb
index 3dc3c879b5..8458685cdc 100644
--- a/spec/ruby/library/cgi/htmlextension/radio_button_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/radio_button_spec.rb
@@ -1,77 +1,80 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#radio_button" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a radio-'input'-element without a name" do
-      output = @html.radio_button
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "radio"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#radio_button" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.radio_button { "test" }
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "radio"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a radio-'input'-element without a name" do
+        output = @html.radio_button
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "radio"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns a radio-'input'-element with the passed name" do
-      output = @html.radio_button("test")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.radio_button { "test" }
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "radio"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.radio_button("test") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns a radio-'input'-element with the passed name" do
+        output = @html.radio_button("test")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio"}, "", not_closed: true)
+      end
 
-  describe "CGI::HtmlExtension#checkbox when passed name, value" do
-    it "returns a radio-'input'-element with the passed name and value" do
-      output = @html.radio_button("test", "test-value")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.radio_button("test") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.radio_button("test", "test-value") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+    describe "CGI::HtmlExtension#checkbox when passed name, value" do
+      it "returns a radio-'input'-element with the passed name and value" do
+        output = @html.radio_button("test", "test-value")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.radio_button("test", "test-value") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed name, value, checked" do
-    it "returns a checked radio-'input'-element with the passed name and value when checked is true" do
-      output = @html.radio_button("test", "test-value", true)
-      output.should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+    describe "when passed name, value, checked" do
+      it "returns a checked radio-'input'-element with the passed name and value when checked is true" do
+        output = @html.radio_button("test", "test-value", true)
+        output.should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
 
-      output = @html.radio_button("test", "test-value", false)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+        output = @html.radio_button("test", "test-value", false)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
 
-      output = @html.radio_button("test", "test-value", nil)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
-    end
+        output = @html.radio_button("test", "test-value", nil)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = @html.radio_button("test", "test-value", nil) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.radio_button("test", "test-value", nil) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "test-value"}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "returns a radio-'input'-element using the passed Hash for attributes" do
-      attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
-      output = @html.radio_button(attributes)
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
-    end
+    describe "when passed Hash" do
+      it "returns a radio-'input'-element using the passed Hash for attributes" do
+        attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
+        output = @html.radio_button(attributes)
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
-      output = @html.radio_button(attributes) { "test" }
-      output.should equal_element("INPUT", attributes, "", not_closed: true)
+      it "ignores a passed block" do
+        attributes = {"NAME" => "test", "VALUE" => "test-value", "CHECKED" => true}
+        output = @html.radio_button(attributes) { "test" }
+        output.should equal_element("INPUT", attributes, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/radio_group_spec.rb b/spec/ruby/library/cgi/htmlextension/radio_group_spec.rb
index 1bfd43449d..fd925a5165 100644
--- a/spec/ruby/library/cgi/htmlextension/radio_group_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/radio_group_spec.rb
@@ -1,77 +1,80 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#radio_group" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed name, values ..." do
-    it "returns a sequence of 'radio'-elements with the passed name and the passed values" do
-      output = CGISpecs.split(@html.radio_group("test", "foo", "bar", "baz"))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+  describe "CGI::HtmlExtension#radio_group" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "allows passing a value inside an Array" do
-      output = CGISpecs.split(@html.radio_group("test", ["foo"], "bar", ["baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
-    end
+    describe "when passed name, values ..." do
+      it "returns a sequence of 'radio'-elements with the passed name and the passed values" do
+        output = CGISpecs.split(@html.radio_group("test", "foo", "bar", "baz"))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
 
-    it "allows passing a value as an Array containing the value and the checked state or a label" do
-      output = CGISpecs.split(@html.radio_group("test", ["foo"], ["bar", true], ["baz", "label for baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "label for baz", not_closed: true)
-    end
+      it "allows passing a value inside an Array" do
+        output = CGISpecs.split(@html.radio_group("test", ["foo"], "bar", ["baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
 
-    # TODO: CGI does not like passing false instead of true.
-    it "allows passing a value as an Array containing the value, a label and the checked state" do
-      output = CGISpecs.split(@html.radio_group("test", ["foo", "label for foo", true], ["bar", "label for bar", false], ["baz", "label for baz", true]))
-      output[0].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "label for foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "label for bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "label for baz", not_closed: true)
-    end
+      it "allows passing a value as an Array containing the value and the checked state or a label" do
+        output = CGISpecs.split(@html.radio_group("test", ["foo"], ["bar", true], ["baz", "label for baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "label for baz", not_closed: true)
+      end
 
-    it "returns an empty String when passed no values" do
-      @html.radio_group("test").should == ""
-    end
+      # TODO: CGI does not like passing false instead of true.
+      it "allows passing a value as an Array containing the value, a label and the checked state" do
+        output = CGISpecs.split(@html.radio_group("test", ["foo", "label for foo", true], ["bar", "label for bar", false], ["baz", "label for baz", true]))
+        output[0].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "label for foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "label for bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "label for baz", not_closed: true)
+      end
+
+      it "returns an empty String when passed no values" do
+        @html.radio_group("test").should == ""
+      end
 
-    it "ignores a passed block" do
-      output = CGISpecs.split(@html.radio_group("test", "foo", "bar", "baz") { "test" })
-      output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      it "ignores a passed block" do
+        output = CGISpecs.split(@html.radio_group("test", "foo", "bar", "baz") { "test" })
+        output[0].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "test", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "uses the passed Hash to generate the radio sequence" do
-      output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+    describe "when passed Hash" do
+      it "uses the passed Hash to generate the radio sequence" do
+        output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
 
-      output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => [["foo"], ["bar", true], "baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+        output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => [["foo"], ["bar", true], "baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
 
-      output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"]))
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "1"}, "Foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "radio", "VALUE" => "2"}, "Bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "Baz"}, "Baz", not_closed: true)
-    end
+        output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => [["1", "Foo"], ["2", "Bar", true], "Baz"]))
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "1"}, "Foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"CHECKED" => true, "NAME" => "name", "TYPE" => "radio", "VALUE" => "2"}, "Bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "Baz"}, "Baz", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]) { "test" })
-      output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
-      output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
-      output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      it "ignores a passed block" do
+        output = CGISpecs.split(@html.radio_group("NAME" => "name", "VALUES" => ["foo", "bar", "baz"]) { "test" })
+        output[0].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "foo"}, "foo", not_closed: true)
+        output[1].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "bar"}, "bar", not_closed: true)
+        output[2].should equal_element("INPUT", {"NAME" => "name", "TYPE" => "radio", "VALUE" => "baz"}, "baz", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/reset_spec.rb b/spec/ruby/library/cgi/htmlextension/reset_spec.rb
index 86fa25fc8a..80e4441b16 100644
--- a/spec/ruby/library/cgi/htmlextension/reset_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/reset_spec.rb
@@ -1,57 +1,60 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#reset" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a reset-'input'-element" do
-      output = @html.reset
-      output.should equal_element("INPUT", {"TYPE" => "reset"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#reset" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.reset { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "reset"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a reset-'input'-element" do
+        output = @html.reset
+        output.should equal_element("INPUT", {"TYPE" => "reset"}, "", not_closed: true)
+      end
 
-  describe "when passed value" do
-    it "returns a reset-'input'-element with the passed value" do
-      output = @html.reset("Example")
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.reset { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "reset"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.reset("Example") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
-    end
-  end
+    describe "when passed value" do
+      it "returns a reset-'input'-element with the passed value" do
+        output = @html.reset("Example")
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      end
 
-  describe "when passed value, name" do
-    it "returns a reset-'input'-element with the passed value and the passed name" do
-      output = @html.reset("Example", "test-name")
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.reset("Example") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.reset("Example", "test-name") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
-    end
-  end
+    describe "when passed value, name" do
+      it "returns a reset-'input'-element with the passed value and the passed name" do
+        output = @html.reset("Example", "test-name")
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      end
 
-  describe "when passed Hash" do
-    it "returns a reset-'input'-element with the passed value" do
-      output = @html.reset("Example")
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.reset("Example", "test-name") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.reset("Example") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a reset-'input'-element with the passed value" do
+        output = @html.reset("Example")
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.reset("Example") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "reset", "VALUE" => "Example"}, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/scrolling_list_spec.rb b/spec/ruby/library/cgi/htmlextension/scrolling_list_spec.rb
index 4eb0c86c1a..b565444679 100644
--- a/spec/ruby/library/cgi/htmlextension/scrolling_list_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/scrolling_list_spec.rb
@@ -1,8 +1,11 @@
 require_relative '../../../spec_helper'
-require_relative 'fixtures/common'
-require 'cgi'
-require_relative 'shared/popup_menu'
 
-describe "CGI::HtmlExtension#scrolling_list" do
-  it_behaves_like :cgi_htmlextension_popup_menu, :scrolling_list
+ruby_version_is ""..."4.0" do
+  require_relative 'fixtures/common'
+  require 'cgi'
+  require_relative 'shared/popup_menu'
+
+  describe "CGI::HtmlExtension#scrolling_list" do
+    it_behaves_like :cgi_htmlextension_popup_menu, :scrolling_list
+  end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/submit_spec.rb b/spec/ruby/library/cgi/htmlextension/submit_spec.rb
index 063891b959..bb6e079c4e 100644
--- a/spec/ruby/library/cgi/htmlextension/submit_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/submit_spec.rb
@@ -1,57 +1,60 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#submit" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns a submit-'input'-element" do
-      output = @html.submit
-      output.should equal_element("INPUT", {"TYPE" => "submit"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#submit" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.submit { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "submit"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns a submit-'input'-element" do
+        output = @html.submit
+        output.should equal_element("INPUT", {"TYPE" => "submit"}, "", not_closed: true)
+      end
 
-  describe "when passed value" do
-    it "returns a submit-'input'-element with the passed value" do
-      output = @html.submit("Example")
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.submit { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "submit"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.submit("Example") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
-    end
-  end
+    describe "when passed value" do
+      it "returns a submit-'input'-element with the passed value" do
+        output = @html.submit("Example")
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      end
 
-  describe "when passed value, name" do
-    it "returns a submit-'input'-element with the passed value and the passed name" do
-      output = @html.submit("Example", "test-name")
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.submit("Example") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.submit("Example", "test-name") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
-    end
-  end
+    describe "when passed value, name" do
+      it "returns a submit-'input'-element with the passed value and the passed name" do
+        output = @html.submit("Example", "test-name")
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      end
 
-  describe "when passed Hash" do
-    it "returns a submit-'input'-element with the passed value" do
-      output = @html.submit("Example")
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.submit("Example", "test-name") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example", "NAME" => "test-name"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.submit("Example") { "test" }
-      output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a submit-'input'-element with the passed value" do
+        output = @html.submit("Example")
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.submit("Example") { "test" }
+        output.should equal_element("INPUT", {"TYPE" => "submit", "VALUE" => "Example"}, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/text_field_spec.rb b/spec/ruby/library/cgi/htmlextension/text_field_spec.rb
index 44b5a5e69f..37e13e3746 100644
--- a/spec/ruby/library/cgi/htmlextension/text_field_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/text_field_spec.rb
@@ -1,84 +1,87 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#text_field" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an text-'input'-element without a name" do
-      output = @html.text_field
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+  describe "CGI::HtmlExtension#text_field" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "ignores a passed block" do
-      output = @html.text_field { "test" }
-      output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an text-'input'-element without a name" do
+        output = @html.text_field
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name" do
-    it "returns an text-'input'-element with the passed name" do
-      output = @html.text_field("test")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.text_field { "test" }
+        output.should equal_element("INPUT", {"NAME" => "", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.text_field("test") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name" do
+      it "returns an text-'input'-element with the passed name" do
+        output = @html.text_field("test")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value" do
-    it "returns an text-'input'-element with the passed name and value" do
-      output = @html.text_field("test", "some value")
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.text_field("test") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.text_field("test", "some value") { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, value" do
+      it "returns an text-'input'-element with the passed name and value" do
+        output = @html.text_field("test", "some value")
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value, size" do
-    it "returns an text-'input'-element with the passed name, value and size" do
-      output = @html.text_field("test", "some value", 60)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.text_field("test", "some value") { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "40"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.text_field("test", "some value", 60) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
-    end
-  end
+    describe "when passed name, value, size" do
+      it "returns an text-'input'-element with the passed name, value and size" do
+        output = @html.text_field("test", "some value", 60)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      end
 
-  describe "when passed name, value, size, maxlength" do
-    it "returns an text-'input'-element with the passed name, value, size and maxlength" do
-      output = @html.text_field("test", "some value", 60, 12)
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.text_field("test", "some value", 60) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60"}, "", not_closed: true)
+      end
     end
 
-    it "ignores a passed block" do
-      output = @html.text_field("test", "some value", 60, 12) { "test" }
-      output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+    describe "when passed name, value, size, maxlength" do
+      it "returns an text-'input'-element with the passed name, value, size and maxlength" do
+        output = @html.text_field("test", "some value", 60, 12)
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      end
+
+      it "ignores a passed block" do
+        output = @html.text_field("test", "some value", 60, 12) { "test" }
+        output.should equal_element("INPUT", {"NAME" => "test", "TYPE" => "text", "VALUE" => "some value", "SIZE" => "60", "MAXLENGTH" => 12}, "", not_closed: true)
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "returns a checkbox-'input'-element using the passed Hash for attributes" do
-      output = @html.text_field("NAME" => "test", "VALUE" => "some value")
-      output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "text" }, "", not_closed: true)
+    describe "when passed Hash" do
+      it "returns a checkbox-'input'-element using the passed Hash for attributes" do
+        output = @html.text_field("NAME" => "test", "VALUE" => "some value")
+        output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "text" }, "", not_closed: true)
 
-      output = @html.text_field("TYPE" => "hidden")
-      output.should equal_element("INPUT", {"TYPE" => "text"}, "", not_closed: true)
-    end
+        output = @html.text_field("TYPE" => "hidden")
+        output.should equal_element("INPUT", {"TYPE" => "text"}, "", not_closed: true)
+      end
 
-    it "ignores a passed block" do
-      output = @html.text_field("NAME" => "test", "VALUE" => "some value") { "test" }
-      output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "text" }, "", not_closed: true)
+      it "ignores a passed block" do
+        output = @html.text_field("NAME" => "test", "VALUE" => "some value") { "test" }
+        output.should equal_element("INPUT", { "NAME" => "test", "VALUE" => "some value", "TYPE" => "text" }, "", not_closed: true)
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/htmlextension/textarea_spec.rb b/spec/ruby/library/cgi/htmlextension/textarea_spec.rb
index db84a973d2..99c6d3dd2d 100644
--- a/spec/ruby/library/cgi/htmlextension/textarea_spec.rb
+++ b/spec/ruby/library/cgi/htmlextension/textarea_spec.rb
@@ -1,73 +1,76 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'fixtures/common'
 
-describe "CGI::HtmlExtension#textarea" do
-  before :each do
-    @html = CGISpecs.cgi_new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'fixtures/common'
 
-  describe "when passed no arguments" do
-    it "returns an 'textarea'-element without a name" do
-      output = @html.textarea
-      output.should equal_element("TEXTAREA", {"NAME" => "", "COLS" => "70", "ROWS" => "10"}, "")
+  describe "CGI::HtmlExtension#textarea" do
+    before :each do
+      @html = CGISpecs.cgi_new
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.textarea { "Example" }
-      output.should equal_element("TEXTAREA", {"NAME" => "", "COLS" => "70", "ROWS" => "10"}, "Example")
-    end
-  end
+    describe "when passed no arguments" do
+      it "returns an 'textarea'-element without a name" do
+        output = @html.textarea
+        output.should equal_element("TEXTAREA", {"NAME" => "", "COLS" => "70", "ROWS" => "10"}, "")
+      end
 
-  describe "when passed name" do
-    it "returns an 'textarea'-element with the passed name" do
-      output = @html.textarea("test")
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "70", "ROWS" => "10"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.textarea { "Example" }
+        output.should equal_element("TEXTAREA", {"NAME" => "", "COLS" => "70", "ROWS" => "10"}, "Example")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.textarea("test") { "Example" }
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "70", "ROWS" => "10"}, "Example")
-    end
-  end
+    describe "when passed name" do
+      it "returns an 'textarea'-element with the passed name" do
+        output = @html.textarea("test")
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "70", "ROWS" => "10"}, "")
+      end
 
-  describe "when passed name, cols" do
-    it "returns an 'textarea'-element with the passed name and the passed amount of columns" do
-      output = @html.textarea("test", 40)
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "10"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.textarea("test") { "Example" }
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "70", "ROWS" => "10"}, "Example")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.textarea("test", 40) { "Example" }
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "10"}, "Example")
-    end
-  end
+    describe "when passed name, cols" do
+      it "returns an 'textarea'-element with the passed name and the passed amount of columns" do
+        output = @html.textarea("test", 40)
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "10"}, "")
+      end
 
-  describe "when passed name, cols, rows" do
-    it "returns an 'textarea'-element with the passed name, the passed amount of columns and the passed number of rows" do
-      output = @html.textarea("test", 40, 5)
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "5"}, "")
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.textarea("test", 40) { "Example" }
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "10"}, "Example")
+      end
     end
 
-    it "includes the return value of the passed block when passed a block" do
-      output = @html.textarea("test", 40, 5) { "Example" }
-      output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "5"}, "Example")
+    describe "when passed name, cols, rows" do
+      it "returns an 'textarea'-element with the passed name, the passed amount of columns and the passed number of rows" do
+        output = @html.textarea("test", 40, 5)
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "5"}, "")
+      end
+
+      it "includes the return value of the passed block when passed a block" do
+        output = @html.textarea("test", 40, 5) { "Example" }
+        output.should equal_element("TEXTAREA", {"NAME" => "test", "COLS" => "40", "ROWS" => "5"}, "Example")
+      end
     end
-  end
 
-  describe "when passed Hash" do
-    it "uses the passed Hash as attributes" do
-      @html.textarea("ID" => "test").should == '<TEXTAREA ID="test"></TEXTAREA>'
+    describe "when passed Hash" do
+      it "uses the passed Hash as attributes" do
+        @html.textarea("ID" => "test").should == '<TEXTAREA ID="test"></TEXTAREA>'
 
-      attributes = {"ID" => "test-id", "NAME" => "test-name"}
-      output = @html.textarea(attributes)
-      output.should equal_element("TEXTAREA", attributes, "")
-    end
+        attributes = {"ID" => "test-id", "NAME" => "test-name"}
+        output = @html.textarea(attributes)
+        output.should equal_element("TEXTAREA", attributes, "")
+      end
 
-    it "includes the return value of the passed block when passed a block" do
-      attributes = {"ID" => "test-id", "NAME" => "test-name"}
-      output = @html.textarea(attributes) { "test" }
-      output.should equal_element("TEXTAREA", attributes, "test")
+      it "includes the return value of the passed block when passed a block" do
+        attributes = {"ID" => "test-id", "NAME" => "test-name"}
+        output = @html.textarea(attributes) { "test" }
+        output.should equal_element("TEXTAREA", attributes, "test")
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/http_header_spec.rb b/spec/ruby/library/cgi/http_header_spec.rb
index 4094bebed3..8d9f3fe9b8 100644
--- a/spec/ruby/library/cgi/http_header_spec.rb
+++ b/spec/ruby/library/cgi/http_header_spec.rb
@@ -1,8 +1,11 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-require_relative 'shared/http_header'
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-describe "CGI#http_header" do
-  it_behaves_like :cgi_http_header, :http_header
+  require_relative 'shared/http_header'
+
+  describe "CGI#http_header" do
+    it_behaves_like :cgi_http_header, :http_header
+  end
 end
diff --git a/spec/ruby/library/cgi/initialize_spec.rb b/spec/ruby/library/cgi/initialize_spec.rb
index f794f157f0..6135522c54 100644
--- a/spec/ruby/library/cgi/initialize_spec.rb
+++ b/spec/ruby/library/cgi/initialize_spec.rb
@@ -1,133 +1,136 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI#initialize" do
-  it "is private" do
-    CGI.should have_private_instance_method(:initialize)
-  end
-end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-describe "CGI#initialize when passed no arguments" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.allocate
-  end
-
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
-
-  it "extends self with CGI::QueryExtension" do
-    @cgi.send(:initialize)
-    @cgi.should be_kind_of(CGI::QueryExtension)
+  describe "CGI#initialize" do
+    it "is private" do
+      CGI.private_instance_methods(false).should.include?(:initialize)
+    end
   end
 
-  it "does not extend self with CGI::HtmlExtension" do
-    @cgi.send(:initialize)
-    @cgi.should_not be_kind_of(CGI::HtmlExtension)
-  end
+  describe "CGI#initialize when passed no arguments" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.allocate
+    end
 
-  it "does not extend self with any of the other HTML modules" do
-    @cgi.send(:initialize)
-    @cgi.should_not be_kind_of(CGI::Html3)
-    @cgi.should_not be_kind_of(CGI::HtmlExtension)
-    @cgi.should_not be_kind_of(CGI::Html4)
-    @cgi.should_not be_kind_of(CGI::Html4Tr)
-    @cgi.should_not be_kind_of(CGI::Html4Fr)
-  end
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "sets #cookies based on ENV['HTTP_COOKIE']" do
-    begin
-      old_env, ENV["HTTP_COOKIE"] = ENV["HTTP_COOKIE"], "test=test yay"
+    it "extends self with CGI::QueryExtension" do
       @cgi.send(:initialize)
-      @cgi.cookies.should == { "test"=>[ "test yay" ] }
-    ensure
-      ENV["HTTP_COOKIE"] = old_env
+      @cgi.should.is_a?(CGI::QueryExtension)
     end
-  end
 
-  it "sets #params based on ENV['QUERY_STRING'] when ENV['REQUEST_METHOD'] is GET" do
-    begin
-      old_env_query, ENV["QUERY_STRING"] = ENV["QUERY_STRING"], "?test=a&test2=b"
-      old_env_method, ENV["REQUEST_METHOD"] = ENV["REQUEST_METHOD"], "GET"
+    it "does not extend self with CGI::HtmlExtension" do
       @cgi.send(:initialize)
-      @cgi.params.should == { "test2" => ["b"], "?test" => ["a"] }
-    ensure
-      ENV["QUERY_STRING"] = old_env_query
-      ENV["REQUEST_METHOD"] = old_env_method
+      @cgi.should_not.is_a?(CGI::HtmlExtension)
     end
-  end
 
-  it "sets #params based on ENV['QUERY_STRING'] when ENV['REQUEST_METHOD'] is HEAD" do
-    begin
-      old_env_query, ENV["QUERY_STRING"] = ENV["QUERY_STRING"], "?test=a&test2=b"
-      old_env_method, ENV["REQUEST_METHOD"] = ENV["REQUEST_METHOD"], "HEAD"
+    it "does not extend self with any of the other HTML modules" do
       @cgi.send(:initialize)
-      @cgi.params.should == { "test2" => ["b"], "?test" => ["a"] }
-    ensure
-      ENV["QUERY_STRING"] = old_env_query
-      ENV["REQUEST_METHOD"] = old_env_method
+      @cgi.should_not.is_a?(CGI::HtmlExtension)
+      @cgi.should_not.is_a?(CGI::Html3)
+      @cgi.should_not.is_a?(CGI::Html4)
+      @cgi.should_not.is_a?(CGI::Html4Tr)
+      @cgi.should_not.is_a?(CGI::Html4Fr)
     end
-  end
-end
 
-describe "CGI#initialize when passed type" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.allocate
-  end
+    it "sets #cookies based on ENV['HTTP_COOKIE']" do
+      begin
+        old_env, ENV["HTTP_COOKIE"] = ENV["HTTP_COOKIE"], "test=test yay"
+        @cgi.send(:initialize)
+        @cgi.cookies.should == { "test"=>[ "test yay" ] }
+      ensure
+        ENV["HTTP_COOKIE"] = old_env
+      end
+    end
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
+    it "sets #params based on ENV['QUERY_STRING'] when ENV['REQUEST_METHOD'] is GET" do
+      begin
+        old_env_query, ENV["QUERY_STRING"] = ENV["QUERY_STRING"], "?test=a&test2=b"
+        old_env_method, ENV["REQUEST_METHOD"] = ENV["REQUEST_METHOD"], "GET"
+        @cgi.send(:initialize)
+        @cgi.params.should == { "test2" => ["b"], "?test" => ["a"] }
+      ensure
+        ENV["QUERY_STRING"] = old_env_query
+        ENV["REQUEST_METHOD"] = old_env_method
+      end
+    end
+
+    it "sets #params based on ENV['QUERY_STRING'] when ENV['REQUEST_METHOD'] is HEAD" do
+      begin
+        old_env_query, ENV["QUERY_STRING"] = ENV["QUERY_STRING"], "?test=a&test2=b"
+        old_env_method, ENV["REQUEST_METHOD"] = ENV["REQUEST_METHOD"], "HEAD"
+        @cgi.send(:initialize)
+        @cgi.params.should == { "test2" => ["b"], "?test" => ["a"] }
+      ensure
+        ENV["QUERY_STRING"] = old_env_query
+        ENV["REQUEST_METHOD"] = old_env_method
+      end
+    end
   end
 
+  describe "CGI#initialize when passed type" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.allocate
+    end
 
-  it "extends self with CGI::QueryExtension" do
-    @cgi.send(:initialize, "test")
-    @cgi.should be_kind_of(CGI::QueryExtension)
-  end
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "extends self with CGI::QueryExtension, CGI::Html3 and CGI::HtmlExtension when the passed type is 'html3'" do
-    @cgi.send(:initialize, "html3")
-    @cgi.should be_kind_of(CGI::Html3)
-    @cgi.should be_kind_of(CGI::HtmlExtension)
-    @cgi.should be_kind_of(CGI::QueryExtension)
 
-    @cgi.should_not be_kind_of(CGI::Html4)
-    @cgi.should_not be_kind_of(CGI::Html4Tr)
-    @cgi.should_not be_kind_of(CGI::Html4Fr)
-  end
+    it "extends self with CGI::QueryExtension" do
+      @cgi.send(:initialize, "test")
+      @cgi.should.is_a?(CGI::QueryExtension)
+    end
 
-  it "extends self with CGI::QueryExtension, CGI::Html4 and CGI::HtmlExtension when the passed type is 'html4'" do
-    @cgi.send(:initialize, "html4")
-    @cgi.should be_kind_of(CGI::Html4)
-    @cgi.should be_kind_of(CGI::HtmlExtension)
-    @cgi.should be_kind_of(CGI::QueryExtension)
+    it "extends self with CGI::QueryExtension, CGI::Html3 and CGI::HtmlExtension when the passed type is 'html3'" do
+      @cgi.send(:initialize, "html3")
+      @cgi.should.is_a?(CGI::Html3)
+      @cgi.should.is_a?(CGI::HtmlExtension)
+      @cgi.should.is_a?(CGI::QueryExtension)
 
-    @cgi.should_not be_kind_of(CGI::Html3)
-    @cgi.should_not be_kind_of(CGI::Html4Tr)
-    @cgi.should_not be_kind_of(CGI::Html4Fr)
-  end
+      @cgi.should_not.is_a?(CGI::Html4)
+      @cgi.should_not.is_a?(CGI::Html4Tr)
+      @cgi.should_not.is_a?(CGI::Html4Fr)
+    end
 
-  it "extends self with CGI::QueryExtension, CGI::Html4Tr and CGI::HtmlExtension when the passed type is 'html4Tr'" do
-    @cgi.send(:initialize, "html4Tr")
-    @cgi.should be_kind_of(CGI::Html4Tr)
-    @cgi.should be_kind_of(CGI::HtmlExtension)
-    @cgi.should be_kind_of(CGI::QueryExtension)
+    it "extends self with CGI::QueryExtension, CGI::Html4 and CGI::HtmlExtension when the passed type is 'html4'" do
+      @cgi.send(:initialize, "html4")
+      @cgi.should.is_a?(CGI::Html4)
+      @cgi.should.is_a?(CGI::HtmlExtension)
+      @cgi.should.is_a?(CGI::QueryExtension)
 
-    @cgi.should_not be_kind_of(CGI::Html3)
-    @cgi.should_not be_kind_of(CGI::Html4)
-    @cgi.should_not be_kind_of(CGI::Html4Fr)
-  end
+      @cgi.should_not.is_a?(CGI::Html3)
+      @cgi.should_not.is_a?(CGI::Html4Tr)
+      @cgi.should_not.is_a?(CGI::Html4Fr)
+    end
 
-  it "extends self with CGI::QueryExtension, CGI::Html4Tr, CGI::Html4Fr and CGI::HtmlExtension when the passed type is 'html4Fr'" do
-    @cgi.send(:initialize, "html4Fr")
-    @cgi.should be_kind_of(CGI::Html4Tr)
-    @cgi.should be_kind_of(CGI::Html4Fr)
-    @cgi.should be_kind_of(CGI::HtmlExtension)
-    @cgi.should be_kind_of(CGI::QueryExtension)
+    it "extends self with CGI::QueryExtension, CGI::Html4Tr and CGI::HtmlExtension when the passed type is 'html4Tr'" do
+      @cgi.send(:initialize, "html4Tr")
+      @cgi.should.is_a?(CGI::Html4Tr)
+      @cgi.should.is_a?(CGI::HtmlExtension)
+      @cgi.should.is_a?(CGI::QueryExtension)
 
-    @cgi.should_not be_kind_of(CGI::Html3)
-    @cgi.should_not be_kind_of(CGI::Html4)
+      @cgi.should_not.is_a?(CGI::Html3)
+      @cgi.should_not.is_a?(CGI::Html4)
+      @cgi.should_not.is_a?(CGI::Html4Fr)
+    end
+
+    it "extends self with CGI::QueryExtension, CGI::Html4Tr, CGI::Html4Fr and CGI::HtmlExtension when the passed type is 'html4Fr'" do
+      @cgi.send(:initialize, "html4Fr")
+      @cgi.should.is_a?(CGI::Html4Tr)
+      @cgi.should.is_a?(CGI::Html4Fr)
+      @cgi.should.is_a?(CGI::HtmlExtension)
+      @cgi.should.is_a?(CGI::QueryExtension)
+
+      @cgi.should_not.is_a?(CGI::Html3)
+      @cgi.should_not.is_a?(CGI::Html4)
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/out_spec.rb b/spec/ruby/library/cgi/out_spec.rb
index bc09f5bcbb..e9eaf5e151 100644
--- a/spec/ruby/library/cgi/out_spec.rb
+++ b/spec/ruby/library/cgi/out_spec.rb
@@ -1,51 +1,54 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI#out" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-    $stdout, @old_stdout = IOStub.new, $stdout
-  end
-
-  after :each do
-    $stdout = @old_stdout
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
-
-  it "it writes a HTMl header based on the passed argument to $stdout" do
-    @cgi.out { "" }
-    $stdout.should == "Content-Type: text/html\r\nContent-Length: 0\r\n\r\n"
-  end
-
-  it "appends the block's return value to the HTML header" do
-    @cgi.out { "test!" }
-    $stdout.should == "Content-Type: text/html\r\nContent-Length: 5\r\n\r\ntest!"
-  end
-
-  it "automatically sets the Content-Length Header based on the block's return value" do
-    @cgi.out { "0123456789" }
-    $stdout.should == "Content-Type: text/html\r\nContent-Length: 10\r\n\r\n0123456789"
-  end
-
-  it "includes Cookies in the @output_cookies field" do
-    @cgi.instance_variable_set(:@output_cookies, ["multiple", "cookies"])
-    @cgi.out { "" }
-    $stdout.should == "Content-Type: text/html\r\nContent-Length: 0\r\nSet-Cookie: multiple\r\nSet-Cookie: cookies\r\n\r\n"
-  end
-end
-
-describe "CGI#out when passed no block" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
-
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
-
-  it "raises a LocalJumpError" do
-    -> { @cgi.out }.should raise_error(LocalJumpError)
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+
+  describe "CGI#out" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+      $stdout, @old_stdout = IOStub.new, $stdout
+    end
+
+    after :each do
+      $stdout = @old_stdout
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
+
+    it "it writes a HTMl header based on the passed argument to $stdout" do
+      @cgi.out { "" }
+      $stdout.should == "Content-Type: text/html\r\nContent-Length: 0\r\n\r\n"
+    end
+
+    it "appends the block's return value to the HTML header" do
+      @cgi.out { "test!" }
+      $stdout.should == "Content-Type: text/html\r\nContent-Length: 5\r\n\r\ntest!"
+    end
+
+    it "automatically sets the Content-Length Header based on the block's return value" do
+      @cgi.out { "0123456789" }
+      $stdout.should == "Content-Type: text/html\r\nContent-Length: 10\r\n\r\n0123456789"
+    end
+
+    it "includes Cookies in the @output_cookies field" do
+      @cgi.instance_variable_set(:@output_cookies, ["multiple", "cookies"])
+      @cgi.out { "" }
+      $stdout.should == "Content-Type: text/html\r\nContent-Length: 0\r\nSet-Cookie: multiple\r\nSet-Cookie: cookies\r\n\r\n"
+    end
+  end
+
+  describe "CGI#out when passed no block" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
+
+    it "raises a LocalJumpError" do
+      -> { @cgi.out }.should.raise(LocalJumpError)
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/parse_spec.rb b/spec/ruby/library/cgi/parse_spec.rb
index 04539b1226..f09270c195 100644
--- a/spec/ruby/library/cgi/parse_spec.rb
+++ b/spec/ruby/library/cgi/parse_spec.rb
@@ -1,24 +1,27 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI.parse when passed String" do
-  it "parses a HTTP Query String into a Hash" do
-    CGI.parse("test=test&a=b").should == { "a" => ["b"], "test" => ["test"] }
-    CGI.parse("test=1,2,3").should == { "test" => ["1,2,3"] }
-    CGI.parse("test=a&a=&b=").should == { "test" => ["a"], "a" => [""], "b" => [""] }
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  it "parses query strings with semicolons in place of ampersands" do
-    CGI.parse("test=test;a=b").should == { "a" => ["b"], "test" => ["test"] }
-    CGI.parse("test=a;a=;b=").should == { "test" => ["a"], "a" => [""], "b" => [""] }
-  end
+  describe "CGI.parse when passed String" do
+    it "parses a HTTP Query String into a Hash" do
+      CGI.parse("test=test&a=b").should == { "a" => ["b"], "test" => ["test"] }
+      CGI.parse("test=1,2,3").should == { "test" => ["1,2,3"] }
+      CGI.parse("test=a&a=&b=").should == { "test" => ["a"], "a" => [""], "b" => [""] }
+    end
 
-  it "allows passing multiple values for one key" do
-    CGI.parse("test=1&test=2&test=3").should == { "test" => ["1", "2", "3"] }
-    CGI.parse("test[]=1&test[]=2&test[]=3").should == { "test[]" => [ "1", "2", "3" ] }
-  end
+    it "parses query strings with semicolons in place of ampersands" do
+      CGI.parse("test=test;a=b").should == { "a" => ["b"], "test" => ["test"] }
+      CGI.parse("test=a;a=;b=").should == { "test" => ["a"], "a" => [""], "b" => [""] }
+    end
+
+    it "allows passing multiple values for one key" do
+      CGI.parse("test=1&test=2&test=3").should == { "test" => ["1", "2", "3"] }
+      CGI.parse("test[]=1&test[]=2&test[]=3").should == { "test[]" => [ "1", "2", "3" ] }
+    end
 
-  it "unescapes keys and values" do
-    CGI.parse("hello%3F=hello%21").should == { "hello?" => ["hello!"] }
+    it "unescapes keys and values" do
+      CGI.parse("hello%3F=hello%21").should == { "hello?" => ["hello!"] }
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/pretty_spec.rb b/spec/ruby/library/cgi/pretty_spec.rb
index a7b7505c15..9df1611037 100644
--- a/spec/ruby/library/cgi/pretty_spec.rb
+++ b/spec/ruby/library/cgi/pretty_spec.rb
@@ -1,24 +1,27 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI.pretty when passed html" do
-  it "indents the passed html String with two spaces" do
-    CGI.pretty("<HTML><BODY></BODY></HTML>").should == <<-EOS
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+
+  describe "CGI.pretty when passed html" do
+    it "indents the passed html String with two spaces" do
+      CGI.pretty("<HTML><BODY></BODY></HTML>").should == <<-EOS
 <HTML>
   <BODY>
   </BODY>
 </HTML>
 EOS
+    end
   end
-end
 
-describe "CGI.pretty when passed html, indentation_unit" do
-  it "indents the passed html String with the passed indentation_unit" do
-    CGI.pretty("<HTML><BODY></BODY></HTML>", "\t").should == <<-EOS
+  describe "CGI.pretty when passed html, indentation_unit" do
+    it "indents the passed html String with the passed indentation_unit" do
+      CGI.pretty("<HTML><BODY></BODY></HTML>", "\t").should == <<-EOS
 <HTML>
 \t<BODY>
 \t</BODY>
 </HTML>
 EOS
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/print_spec.rb b/spec/ruby/library/cgi/print_spec.rb
index 18ab8d673b..f4f461c5c0 100644
--- a/spec/ruby/library/cgi/print_spec.rb
+++ b/spec/ruby/library/cgi/print_spec.rb
@@ -1,26 +1,29 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI#print" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI#print" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
 
-  it "passes all arguments to $stdout.print" do
-    $stdout.should_receive(:print).with("test")
-    @cgi.print("test")
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-    $stdout.should_receive(:print).with("one", "two", "three", ["four", "five"])
-    @cgi.print("one", "two", "three", ["four", "five"])
-  end
+    it "passes all arguments to $stdout.print" do
+      $stdout.should_receive(:print).with("test")
+      @cgi.print("test")
+
+      $stdout.should_receive(:print).with("one", "two", "three", ["four", "five"])
+      @cgi.print("one", "two", "three", ["four", "five"])
+    end
 
-  it "returns the result of calling $stdout.print" do
-    $stdout.should_receive(:print).with("test").and_return(:expected)
-    @cgi.print("test").should == :expected
+    it "returns the result of calling $stdout.print" do
+      $stdout.should_receive(:print).with("test").and_return(:expected)
+      @cgi.print("test").should == :expected
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/accept_charset_spec.rb b/spec/ruby/library/cgi/queryextension/accept_charset_spec.rb
index 0487569b9c..be05f0c175 100644
--- a/spec/ruby/library/cgi/queryextension/accept_charset_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/accept_charset_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#accept_charset" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#accept_charset" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_ACCEPT_CHARSET']" do
-    old_value, ENV['HTTP_ACCEPT_CHARSET'] = ENV['HTTP_ACCEPT_CHARSET'], "ISO-8859-1,utf-8;q=0.7,*;q=0.7"
-    begin
-      @cgi.accept_charset.should == "ISO-8859-1,utf-8;q=0.7,*;q=0.7"
-    ensure
-      ENV['HTTP_ACCEPT_CHARSET'] = old_value
+    it "returns ENV['HTTP_ACCEPT_CHARSET']" do
+      old_value, ENV['HTTP_ACCEPT_CHARSET'] = ENV['HTTP_ACCEPT_CHARSET'], "ISO-8859-1,utf-8;q=0.7,*;q=0.7"
+      begin
+        @cgi.accept_charset.should == "ISO-8859-1,utf-8;q=0.7,*;q=0.7"
+      ensure
+        ENV['HTTP_ACCEPT_CHARSET'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/accept_encoding_spec.rb b/spec/ruby/library/cgi/queryextension/accept_encoding_spec.rb
index 35ff3c2b30..42eb4a49b5 100644
--- a/spec/ruby/library/cgi/queryextension/accept_encoding_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/accept_encoding_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#accept_encoding" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#accept_encoding" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_ACCEPT_ENCODING']" do
-    old_value, ENV['HTTP_ACCEPT_ENCODING'] = ENV['HTTP_ACCEPT_ENCODING'], "gzip,deflate"
-    begin
-      @cgi.accept_encoding.should == "gzip,deflate"
-    ensure
-      ENV['HTTP_ACCEPT_ENCODING'] = old_value
+    it "returns ENV['HTTP_ACCEPT_ENCODING']" do
+      old_value, ENV['HTTP_ACCEPT_ENCODING'] = ENV['HTTP_ACCEPT_ENCODING'], "gzip,deflate"
+      begin
+        @cgi.accept_encoding.should == "gzip,deflate"
+      ensure
+        ENV['HTTP_ACCEPT_ENCODING'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/accept_language_spec.rb b/spec/ruby/library/cgi/queryextension/accept_language_spec.rb
index 4a15d58914..19f29c6345 100644
--- a/spec/ruby/library/cgi/queryextension/accept_language_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/accept_language_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#accept_language" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#accept_language" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_ACCEPT_LANGUAGE']" do
-    old_value, ENV['HTTP_ACCEPT_LANGUAGE'] = ENV['HTTP_ACCEPT_LANGUAGE'], "en-us,en;q=0.5"
-    begin
-      @cgi.accept_language.should == "en-us,en;q=0.5"
-    ensure
-      ENV['HTTP_ACCEPT_LANGUAGE'] = old_value
+    it "returns ENV['HTTP_ACCEPT_LANGUAGE']" do
+      old_value, ENV['HTTP_ACCEPT_LANGUAGE'] = ENV['HTTP_ACCEPT_LANGUAGE'], "en-us,en;q=0.5"
+      begin
+        @cgi.accept_language.should == "en-us,en;q=0.5"
+      ensure
+        ENV['HTTP_ACCEPT_LANGUAGE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/accept_spec.rb b/spec/ruby/library/cgi/queryextension/accept_spec.rb
index af5209ffbe..dcae39a736 100644
--- a/spec/ruby/library/cgi/queryextension/accept_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/accept_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#accept" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#accept" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_ACCEPT']" do
-    old_value, ENV['HTTP_ACCEPT'] = ENV['HTTP_ACCEPT'], "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"
-    begin
-      @cgi.accept.should == "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"
-    ensure
-      ENV['HTTP_ACCEPT'] = old_value
+    it "returns ENV['HTTP_ACCEPT']" do
+      old_value, ENV['HTTP_ACCEPT'] = ENV['HTTP_ACCEPT'], "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"
+      begin
+        @cgi.accept.should == "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"
+      ensure
+        ENV['HTTP_ACCEPT'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/auth_type_spec.rb b/spec/ruby/library/cgi/queryextension/auth_type_spec.rb
index 25318269b1..75e9cdb27a 100644
--- a/spec/ruby/library/cgi/queryextension/auth_type_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/auth_type_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#auth_type" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#auth_type" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['AUTH_TYPE']" do
-    old_value, ENV['AUTH_TYPE'] = ENV['AUTH_TYPE'], "Basic"
-    begin
-      @cgi.auth_type.should == "Basic"
-    ensure
-      ENV['AUTH_TYPE'] = old_value
+    it "returns ENV['AUTH_TYPE']" do
+      old_value, ENV['AUTH_TYPE'] = ENV['AUTH_TYPE'], "Basic"
+      begin
+        @cgi.auth_type.should == "Basic"
+      ensure
+        ENV['AUTH_TYPE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/cache_control_spec.rb b/spec/ruby/library/cgi/queryextension/cache_control_spec.rb
index 0471307c22..c4b727e671 100644
--- a/spec/ruby/library/cgi/queryextension/cache_control_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/cache_control_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#cache_control" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#cache_control" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_CACHE_CONTROL']" do
-    old_value, ENV['HTTP_CACHE_CONTROL'] = ENV['HTTP_CACHE_CONTROL'], "no-cache"
-    begin
-      @cgi.cache_control.should == "no-cache"
-    ensure
-      ENV['HTTP_CACHE_CONTROL'] = old_value
+    it "returns ENV['HTTP_CACHE_CONTROL']" do
+      old_value, ENV['HTTP_CACHE_CONTROL'] = ENV['HTTP_CACHE_CONTROL'], "no-cache"
+      begin
+        @cgi.cache_control.should == "no-cache"
+      ensure
+        ENV['HTTP_CACHE_CONTROL'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/content_length_spec.rb b/spec/ruby/library/cgi/queryextension/content_length_spec.rb
index de823f7119..bd02f3d8da 100644
--- a/spec/ruby/library/cgi/queryextension/content_length_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/content_length_spec.rb
@@ -1,26 +1,29 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#content_length" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#content_length" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['CONTENT_LENGTH'] as Integer" do
-    old_value = ENV['CONTENT_LENGTH']
-    begin
-      ENV['CONTENT_LENGTH'] = nil
-      @cgi.content_length.should be_nil
+    it "returns ENV['CONTENT_LENGTH'] as Integer" do
+      old_value = ENV['CONTENT_LENGTH']
+      begin
+        ENV['CONTENT_LENGTH'] = nil
+        @cgi.content_length.should == nil
 
-      ENV['CONTENT_LENGTH'] = "100"
-      @cgi.content_length.should eql(100)
-    ensure
-      ENV['CONTENT_LENGTH'] = old_value
+        ENV['CONTENT_LENGTH'] = "100"
+        @cgi.content_length.should.eql?(100)
+      ensure
+        ENV['CONTENT_LENGTH'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/content_type_spec.rb b/spec/ruby/library/cgi/queryextension/content_type_spec.rb
index 49b8389c87..d3cbdf0b14 100644
--- a/spec/ruby/library/cgi/queryextension/content_type_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/content_type_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#content_type" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#content_type" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['CONTENT_TYPE']" do
-    old_value, ENV['CONTENT_TYPE'] = ENV['CONTENT_TYPE'], "text/html"
-    begin
-      @cgi.content_type.should == "text/html"
-    ensure
-      ENV['CONTENT_TYPE'] = old_value
+    it "returns ENV['CONTENT_TYPE']" do
+      old_value, ENV['CONTENT_TYPE'] = ENV['CONTENT_TYPE'], "text/html"
+      begin
+        @cgi.content_type.should == "text/html"
+      ensure
+        ENV['CONTENT_TYPE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/cookies_spec.rb b/spec/ruby/library/cgi/queryextension/cookies_spec.rb
index 4befd61ab7..266fe0c721 100644
--- a/spec/ruby/library/cgi/queryextension/cookies_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/cookies_spec.rb
@@ -1,10 +1,13 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#cookies" do
-  it "needs to be reviewed for spec completeness"
-end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+
+  describe "CGI::QueryExtension#cookies" do
+    it "needs to be reviewed for spec completeness"
+  end
 
-describe "CGI::QueryExtension#cookies=" do
-  it "needs to be reviewed for spec completeness"
+  describe "CGI::QueryExtension#cookies=" do
+    it "needs to be reviewed for spec completeness"
+  end
 end
diff --git a/spec/ruby/library/cgi/queryextension/element_reference_spec.rb b/spec/ruby/library/cgi/queryextension/element_reference_spec.rb
index 6ac5b46407..c835f385f0 100644
--- a/spec/ruby/library/cgi/queryextension/element_reference_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/element_reference_spec.rb
@@ -1,27 +1,30 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#[]" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    ENV['QUERY_STRING'], @old_query_string = "one=a&two=b&two=c", ENV['QUERY_STRING']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-    ENV['QUERY_STRING']   = @old_query_string
-  end
+  describe "CGI::QueryExtension#[]" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      ENV['QUERY_STRING'], @old_query_string = "one=a&two=b&two=c", ENV['QUERY_STRING']
+      @cgi = CGI.new
+    end
 
-  it "it returns the value for the parameter with the given key" do
-    @cgi["one"].should == "a"
-  end
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+      ENV['QUERY_STRING']   = @old_query_string
+    end
 
-  it "only returns the first value for parameters with multiple values" do
-    @cgi["two"].should == "b"
-  end
+    it "it returns the value for the parameter with the given key" do
+      @cgi["one"].should == "a"
+    end
+
+    it "only returns the first value for parameters with multiple values" do
+      @cgi["two"].should == "b"
+    end
 
-  it "returns a String" do
-    @cgi["one"].should be_kind_of(String)
+    it "returns a String" do
+      @cgi["one"].should.is_a?(String)
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/from_spec.rb b/spec/ruby/library/cgi/queryextension/from_spec.rb
index 04a992cfc7..b341e0be10 100644
--- a/spec/ruby/library/cgi/queryextension/from_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/from_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#from" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#from" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_FROM']" do
-    old_value, ENV['HTTP_FROM'] = ENV['HTTP_FROM'], "googlebot(at)googlebot.com"
-    begin
-      @cgi.from.should == "googlebot(at)googlebot.com"
-    ensure
-      ENV['HTTP_FROM'] = old_value
+    it "returns ENV['HTTP_FROM']" do
+      old_value, ENV['HTTP_FROM'] = ENV['HTTP_FROM'], "googlebot(at)googlebot.com"
+      begin
+        @cgi.from.should == "googlebot(at)googlebot.com"
+      ensure
+        ENV['HTTP_FROM'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/gateway_interface_spec.rb b/spec/ruby/library/cgi/queryextension/gateway_interface_spec.rb
index 3ead5bd8bf..c82522326b 100644
--- a/spec/ruby/library/cgi/queryextension/gateway_interface_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/gateway_interface_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#gateway_interface" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#gateway_interface" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['GATEWAY_INTERFACE']" do
-    old_value, ENV['GATEWAY_INTERFACE'] = ENV['GATEWAY_INTERFACE'], "CGI/1.1"
-    begin
-      @cgi.gateway_interface.should == "CGI/1.1"
-    ensure
-      ENV['GATEWAY_INTERFACE'] = old_value
+    it "returns ENV['GATEWAY_INTERFACE']" do
+      old_value, ENV['GATEWAY_INTERFACE'] = ENV['GATEWAY_INTERFACE'], "CGI/1.1"
+      begin
+        @cgi.gateway_interface.should == "CGI/1.1"
+      ensure
+        ENV['GATEWAY_INTERFACE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/has_key_spec.rb b/spec/ruby/library/cgi/queryextension/has_key_spec.rb
index 525b45b507..43f7aae1b2 100644
--- a/spec/ruby/library/cgi/queryextension/has_key_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/has_key_spec.rb
@@ -1,7 +1,10 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'shared/has_key'
 
-describe "CGI::QueryExtension#has_key?" do
-  it_behaves_like :cgi_query_extension_has_key_p, :has_key?
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'shared/has_key'
+
+  describe "CGI::QueryExtension#has_key?" do
+    it_behaves_like :cgi_query_extension_has_key_p, :has_key?
+  end
 end
diff --git a/spec/ruby/library/cgi/queryextension/host_spec.rb b/spec/ruby/library/cgi/queryextension/host_spec.rb
index e820e0afc3..e1047c942b 100644
--- a/spec/ruby/library/cgi/queryextension/host_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/host_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#host" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#host" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_HOST']" do
-    old_value, ENV['HTTP_HOST'] = ENV['HTTP_HOST'], "localhost"
-    begin
-      @cgi.host.should == "localhost"
-    ensure
-      ENV['HTTP_HOST'] = old_value
+    it "returns ENV['HTTP_HOST']" do
+      old_value, ENV['HTTP_HOST'] = ENV['HTTP_HOST'], "localhost"
+      begin
+        @cgi.host.should == "localhost"
+      ensure
+        ENV['HTTP_HOST'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/include_spec.rb b/spec/ruby/library/cgi/queryextension/include_spec.rb
index 12365ea284..7275c309f9 100644
--- a/spec/ruby/library/cgi/queryextension/include_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/include_spec.rb
@@ -1,7 +1,10 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'shared/has_key'
 
-describe "CGI::QueryExtension#include?" do
-  it_behaves_like :cgi_query_extension_has_key_p, :include?
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'shared/has_key'
+
+  describe "CGI::QueryExtension#include?" do
+    it_behaves_like :cgi_query_extension_has_key_p, :include?
+  end
 end
diff --git a/spec/ruby/library/cgi/queryextension/key_spec.rb b/spec/ruby/library/cgi/queryextension/key_spec.rb
index d0f1e4cee2..dc2f52fbe0 100644
--- a/spec/ruby/library/cgi/queryextension/key_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/key_spec.rb
@@ -1,7 +1,10 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require_relative 'shared/has_key'
 
-describe "CGI::QueryExtension#key?" do
-  it_behaves_like :cgi_query_extension_has_key_p, :key?
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require_relative 'shared/has_key'
+
+  describe "CGI::QueryExtension#key?" do
+    it_behaves_like :cgi_query_extension_has_key_p, :key?
+  end
 end
diff --git a/spec/ruby/library/cgi/queryextension/keys_spec.rb b/spec/ruby/library/cgi/queryextension/keys_spec.rb
index 14d77180fa..bb16914065 100644
--- a/spec/ruby/library/cgi/queryextension/keys_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/keys_spec.rb
@@ -1,20 +1,23 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#keys" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    ENV['QUERY_STRING'], @old_query_string = "one=a&two=b", ENV['QUERY_STRING']
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-    @cgi = CGI.new
-  end
+  describe "CGI::QueryExtension#keys" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      ENV['QUERY_STRING'], @old_query_string = "one=a&two=b", ENV['QUERY_STRING']
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-    ENV['QUERY_STRING']   = @old_query_string
-  end
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+      ENV['QUERY_STRING']   = @old_query_string
+    end
 
-  it "returns all parameter keys as an Array" do
-    @cgi.keys.sort.should == ["one", "two"]
+    it "returns all parameter keys as an Array" do
+      @cgi.keys.sort.should == ["one", "two"]
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/multipart_spec.rb b/spec/ruby/library/cgi/queryextension/multipart_spec.rb
index ced4cb05a1..1fa771ca1c 100644
--- a/spec/ruby/library/cgi/queryextension/multipart_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/multipart_spec.rb
@@ -1,20 +1,22 @@
 require_relative '../../../spec_helper'
-require 'cgi'
-require "stringio"
 
-describe "CGI::QueryExtension#multipart?" do
-  before :each do
-    @old_stdin = $stdin
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+  require "stringio"
 
-    @old_request_method = ENV['REQUEST_METHOD']
-    @old_content_type = ENV['CONTENT_TYPE']
-    @old_content_length = ENV['CONTENT_LENGTH']
+  describe "CGI::QueryExtension#multipart?" do
+    before :each do
+      @old_stdin = $stdin
 
-    ENV['REQUEST_METHOD'] = "POST"
-    ENV["CONTENT_TYPE"] = "multipart/form-data; boundary=---------------------------1137522503144128232716531729"
-    ENV["CONTENT_LENGTH"] = "222"
+      @old_request_method = ENV['REQUEST_METHOD']
+      @old_content_type = ENV['CONTENT_TYPE']
+      @old_content_length = ENV['CONTENT_LENGTH']
 
-    $stdin = StringIO.new <<-EOS
+      ENV['REQUEST_METHOD'] = "POST"
+      ENV["CONTENT_TYPE"] = "multipart/form-data; boundary=---------------------------1137522503144128232716531729"
+      ENV["CONTENT_LENGTH"] = "222"
+
+      $stdin = StringIO.new <<-EOS
 -----------------------------1137522503144128232716531729\r
 Content-Disposition: form-data; name="file"; filename=""\r
 Content-Type: application/octet-stream\r
@@ -23,18 +25,19 @@ Content-Type: application/octet-stream\r
 -----------------------------1137522503144128232716531729--\r
 EOS
 
-    @cgi = CGI.new
-  end
+      @cgi = CGI.new
+    end
 
-  after :each do
-    $stdin = @old_stdin
+    after :each do
+      $stdin = @old_stdin
 
-    ENV['REQUEST_METHOD'] = @old_request_method
-    ENV['CONTENT_TYPE'] = @old_content_type
-    ENV['CONTENT_LENGTH'] = @old_content_length
-  end
+      ENV['REQUEST_METHOD'] = @old_request_method
+      ENV['CONTENT_TYPE'] = @old_content_type
+      ENV['CONTENT_LENGTH'] = @old_content_length
+    end
 
-  it "returns true if the current Request is a multipart request" do
-    @cgi.multipart?.should be_true
+    it "returns true if the current Request is a multipart request" do
+      @cgi.multipart?.should == true
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/negotiate_spec.rb b/spec/ruby/library/cgi/queryextension/negotiate_spec.rb
index b6fe036042..4083e6a8cd 100644
--- a/spec/ruby/library/cgi/queryextension/negotiate_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/negotiate_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#negotiate" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#negotiate" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_NEGOTIATE']" do
-    old_value, ENV['HTTP_NEGOTIATE'] = ENV['HTTP_NEGOTIATE'], "trans"
-    begin
-      @cgi.negotiate.should == "trans"
-    ensure
-      ENV['HTTP_NEGOTIATE'] = old_value
+    it "returns ENV['HTTP_NEGOTIATE']" do
+      old_value, ENV['HTTP_NEGOTIATE'] = ENV['HTTP_NEGOTIATE'], "trans"
+      begin
+        @cgi.negotiate.should == "trans"
+      ensure
+        ENV['HTTP_NEGOTIATE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/params_spec.rb b/spec/ruby/library/cgi/queryextension/params_spec.rb
index f4449e3c8a..938028ea14 100644
--- a/spec/ruby/library/cgi/queryextension/params_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/params_spec.rb
@@ -1,37 +1,40 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#params" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    ENV['QUERY_STRING'], @old_query_string = "one=a&two=b&two=c&three", ENV['QUERY_STRING']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['QUERY_STRING'] = @old_query_string
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#params" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      ENV['QUERY_STRING'], @old_query_string = "one=a&two=b&two=c&three", ENV['QUERY_STRING']
+      @cgi = CGI.new
+    end
 
-  it "returns the parsed HTTP Query Params" do
-    @cgi.params.should == {"three"=>[], "two"=>["b", "c"], "one"=>["a"]}
-  end
-end
+    after :each do
+      ENV['QUERY_STRING'] = @old_query_string
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-describe "CGI::QueryExtension#params=" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
+    it "returns the parsed HTTP Query Params" do
+      @cgi.params.should == {"three"=>[], "two"=>["b", "c"], "one"=>["a"]}
+    end
   end
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#params=" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "sets the HTTP Query Params to the passed argument" do
-    @cgi.params.should == {}
+    it "sets the HTTP Query Params to the passed argument" do
+      @cgi.params.should == {}
 
-    @cgi.params = {"one"=>["a"], "two"=>["b", "c"]}
-    @cgi.params.should == {"one"=>["a"], "two"=>["b", "c"]}
+      @cgi.params = {"one"=>["a"], "two"=>["b", "c"]}
+      @cgi.params.should == {"one"=>["a"], "two"=>["b", "c"]}
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/path_info_spec.rb b/spec/ruby/library/cgi/queryextension/path_info_spec.rb
index 9785df85f1..9b7834c514 100644
--- a/spec/ruby/library/cgi/queryextension/path_info_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/path_info_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#path_info" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#path_info" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['PATH_INFO']" do
-    old_value, ENV['PATH_INFO'] = ENV['PATH_INFO'], "/test/path"
-    begin
-      @cgi.path_info.should == "/test/path"
-    ensure
-      ENV['PATH_INFO'] = old_value
+    it "returns ENV['PATH_INFO']" do
+      old_value, ENV['PATH_INFO'] = ENV['PATH_INFO'], "/test/path"
+      begin
+        @cgi.path_info.should == "/test/path"
+      ensure
+        ENV['PATH_INFO'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/path_translated_spec.rb b/spec/ruby/library/cgi/queryextension/path_translated_spec.rb
index 417a749341..a773aaafdb 100644
--- a/spec/ruby/library/cgi/queryextension/path_translated_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/path_translated_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#path_translated" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#path_translated" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['PATH_TRANSLATED']" do
-    old_value, ENV['PATH_TRANSLATED'] = ENV['PATH_TRANSLATED'], "/full/path/to/dir"
-    begin
-      @cgi.path_translated.should == "/full/path/to/dir"
-    ensure
-      ENV['PATH_TRANSLATED'] = old_value
+    it "returns ENV['PATH_TRANSLATED']" do
+      old_value, ENV['PATH_TRANSLATED'] = ENV['PATH_TRANSLATED'], "/full/path/to/dir"
+      begin
+        @cgi.path_translated.should == "/full/path/to/dir"
+      ensure
+        ENV['PATH_TRANSLATED'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/pragma_spec.rb b/spec/ruby/library/cgi/queryextension/pragma_spec.rb
index 02d5c91221..be384182a5 100644
--- a/spec/ruby/library/cgi/queryextension/pragma_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/pragma_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#pragma" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#pragma" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_PRAGMA']" do
-    old_value, ENV['HTTP_PRAGMA'] = ENV['HTTP_PRAGMA'], "no-cache"
-    begin
-      @cgi.pragma.should == "no-cache"
-    ensure
-      ENV['HTTP_PRAGMA'] = old_value
+    it "returns ENV['HTTP_PRAGMA']" do
+      old_value, ENV['HTTP_PRAGMA'] = ENV['HTTP_PRAGMA'], "no-cache"
+      begin
+        @cgi.pragma.should == "no-cache"
+      ensure
+        ENV['HTTP_PRAGMA'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/query_string_spec.rb b/spec/ruby/library/cgi/queryextension/query_string_spec.rb
index a6b454a7eb..64fbeaea10 100644
--- a/spec/ruby/library/cgi/queryextension/query_string_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/query_string_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#query_string" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#query_string" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['QUERY_STRING']" do
-    old_value, ENV['QUERY_STRING'] = ENV['QUERY_STRING'], "one=a&two=b"
-    begin
-      @cgi.query_string.should == "one=a&two=b"
-    ensure
-      ENV['QUERY_STRING'] = old_value
+    it "returns ENV['QUERY_STRING']" do
+      old_value, ENV['QUERY_STRING'] = ENV['QUERY_STRING'], "one=a&two=b"
+      begin
+        @cgi.query_string.should == "one=a&two=b"
+      ensure
+        ENV['QUERY_STRING'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/raw_cookie2_spec.rb b/spec/ruby/library/cgi/queryextension/raw_cookie2_spec.rb
index 3d7072e346..30d314aca1 100644
--- a/spec/ruby/library/cgi/queryextension/raw_cookie2_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/raw_cookie2_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#raw_cookie2" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#raw_cookie2" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_COOKIE2']" do
-    old_value, ENV['HTTP_COOKIE2'] = ENV['HTTP_COOKIE2'], "some_cookie=data"
-    begin
-      @cgi.raw_cookie2.should == "some_cookie=data"
-    ensure
-      ENV['HTTP_COOKIE2'] = old_value
+    it "returns ENV['HTTP_COOKIE2']" do
+      old_value, ENV['HTTP_COOKIE2'] = ENV['HTTP_COOKIE2'], "some_cookie=data"
+      begin
+        @cgi.raw_cookie2.should == "some_cookie=data"
+      ensure
+        ENV['HTTP_COOKIE2'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/raw_cookie_spec.rb b/spec/ruby/library/cgi/queryextension/raw_cookie_spec.rb
index ede7b9ff87..affa504b39 100644
--- a/spec/ruby/library/cgi/queryextension/raw_cookie_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/raw_cookie_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#raw_cookie" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#raw_cookie" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_COOKIE']" do
-    old_value, ENV['HTTP_COOKIE'] = ENV['HTTP_COOKIE'], "some_cookie=data"
-    begin
-      @cgi.raw_cookie.should == "some_cookie=data"
-    ensure
-      ENV['HTTP_COOKIE'] = old_value
+    it "returns ENV['HTTP_COOKIE']" do
+      old_value, ENV['HTTP_COOKIE'] = ENV['HTTP_COOKIE'], "some_cookie=data"
+      begin
+        @cgi.raw_cookie.should == "some_cookie=data"
+      ensure
+        ENV['HTTP_COOKIE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/referer_spec.rb b/spec/ruby/library/cgi/queryextension/referer_spec.rb
index 6cd5dc96f8..53fc19ddd0 100644
--- a/spec/ruby/library/cgi/queryextension/referer_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/referer_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#referer" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#referer" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_REFERER']" do
-    old_value, ENV['HTTP_REFERER'] = ENV['HTTP_REFERER'], "example.com"
-    begin
-      @cgi.referer.should == "example.com"
-    ensure
-      ENV['HTTP_REFERER'] = old_value
+    it "returns ENV['HTTP_REFERER']" do
+      old_value, ENV['HTTP_REFERER'] = ENV['HTTP_REFERER'], "example.com"
+      begin
+        @cgi.referer.should == "example.com"
+      ensure
+        ENV['HTTP_REFERER'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/remote_addr_spec.rb b/spec/ruby/library/cgi/queryextension/remote_addr_spec.rb
index 0259402b23..7b5addc2d5 100644
--- a/spec/ruby/library/cgi/queryextension/remote_addr_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/remote_addr_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#remote_addr" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#remote_addr" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['REMOTE_ADDR']" do
-    old_value, ENV['REMOTE_ADDR'] = ENV['REMOTE_ADDR'], "127.0.0.1"
-    begin
-      @cgi.remote_addr.should == "127.0.0.1"
-    ensure
-      ENV['REMOTE_ADDR'] = old_value
+    it "returns ENV['REMOTE_ADDR']" do
+      old_value, ENV['REMOTE_ADDR'] = ENV['REMOTE_ADDR'], "127.0.0.1"
+      begin
+        @cgi.remote_addr.should == "127.0.0.1"
+      ensure
+        ENV['REMOTE_ADDR'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/remote_host_spec.rb b/spec/ruby/library/cgi/queryextension/remote_host_spec.rb
index cf77e0031b..2dfe59ca38 100644
--- a/spec/ruby/library/cgi/queryextension/remote_host_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/remote_host_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#remote_host" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#remote_host" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['REMOTE_HOST']" do
-    old_value, ENV['REMOTE_HOST'] = ENV['REMOTE_HOST'], "test.host"
-    begin
-      @cgi.remote_host.should == "test.host"
-    ensure
-      ENV['REMOTE_HOST'] = old_value
+    it "returns ENV['REMOTE_HOST']" do
+      old_value, ENV['REMOTE_HOST'] = ENV['REMOTE_HOST'], "test.host"
+      begin
+        @cgi.remote_host.should == "test.host"
+      ensure
+        ENV['REMOTE_HOST'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/remote_ident_spec.rb b/spec/ruby/library/cgi/queryextension/remote_ident_spec.rb
index 5b51d6b8ee..bb05fc7942 100644
--- a/spec/ruby/library/cgi/queryextension/remote_ident_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/remote_ident_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#remote_ident" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#remote_ident" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['REMOTE_IDENT']" do
-    old_value, ENV['REMOTE_IDENT'] = ENV['REMOTE_IDENT'], "no-idea-what-this-is-for"
-    begin
-      @cgi.remote_ident.should == "no-idea-what-this-is-for"
-    ensure
-      ENV['REMOTE_IDENT'] = old_value
+    it "returns ENV['REMOTE_IDENT']" do
+      old_value, ENV['REMOTE_IDENT'] = ENV['REMOTE_IDENT'], "no-idea-what-this-is-for"
+      begin
+        @cgi.remote_ident.should == "no-idea-what-this-is-for"
+      ensure
+        ENV['REMOTE_IDENT'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/remote_user_spec.rb b/spec/ruby/library/cgi/queryextension/remote_user_spec.rb
index 1a93bb6561..29856302ab 100644
--- a/spec/ruby/library/cgi/queryextension/remote_user_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/remote_user_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#remote_user" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#remote_user" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['REMOTE_USER']" do
-    old_value, ENV['REMOTE_USER'] = ENV['REMOTE_USER'], "username"
-    begin
-      @cgi.remote_user.should == "username"
-    ensure
-      ENV['REMOTE_USER'] = old_value
+    it "returns ENV['REMOTE_USER']" do
+      old_value, ENV['REMOTE_USER'] = ENV['REMOTE_USER'], "username"
+      begin
+        @cgi.remote_user.should == "username"
+      ensure
+        ENV['REMOTE_USER'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/request_method_spec.rb b/spec/ruby/library/cgi/queryextension/request_method_spec.rb
index eabdd6998b..7331b134d2 100644
--- a/spec/ruby/library/cgi/queryextension/request_method_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/request_method_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#request_method" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#request_method" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['REQUEST_METHOD']" do
-    old_value, ENV['REQUEST_METHOD'] = ENV['REQUEST_METHOD'], "GET"
-    begin
-      @cgi.request_method.should == "GET"
-    ensure
-      ENV['REQUEST_METHOD'] = old_value
+    it "returns ENV['REQUEST_METHOD']" do
+      old_value, ENV['REQUEST_METHOD'] = ENV['REQUEST_METHOD'], "GET"
+      begin
+        @cgi.request_method.should == "GET"
+      ensure
+        ENV['REQUEST_METHOD'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/script_name_spec.rb b/spec/ruby/library/cgi/queryextension/script_name_spec.rb
index 341b7b6fea..4b359a545f 100644
--- a/spec/ruby/library/cgi/queryextension/script_name_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/script_name_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#script_name" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#script_name" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['SCRIPT_NAME']" do
-    old_value, ENV['SCRIPT_NAME'] = ENV['SCRIPT_NAME'], "/path/to/script.rb"
-    begin
-      @cgi.script_name.should == "/path/to/script.rb"
-    ensure
-      ENV['SCRIPT_NAME'] = old_value
+    it "returns ENV['SCRIPT_NAME']" do
+      old_value, ENV['SCRIPT_NAME'] = ENV['SCRIPT_NAME'], "/path/to/script.rb"
+      begin
+        @cgi.script_name.should == "/path/to/script.rb"
+      ensure
+        ENV['SCRIPT_NAME'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/server_name_spec.rb b/spec/ruby/library/cgi/queryextension/server_name_spec.rb
index b12aaf8c5c..c1f7fb4c54 100644
--- a/spec/ruby/library/cgi/queryextension/server_name_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/server_name_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#server_name" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#server_name" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['SERVER_NAME']" do
-    old_value, ENV['SERVER_NAME'] = ENV['SERVER_NAME'], "localhost"
-    begin
-      @cgi.server_name.should == "localhost"
-    ensure
-      ENV['SERVER_NAME'] = old_value
+    it "returns ENV['SERVER_NAME']" do
+      old_value, ENV['SERVER_NAME'] = ENV['SERVER_NAME'], "localhost"
+      begin
+        @cgi.server_name.should == "localhost"
+      ensure
+        ENV['SERVER_NAME'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/server_port_spec.rb b/spec/ruby/library/cgi/queryextension/server_port_spec.rb
index 0e688a99bf..1c88d3225d 100644
--- a/spec/ruby/library/cgi/queryextension/server_port_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/server_port_spec.rb
@@ -1,26 +1,29 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#server_port" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#server_port" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['SERVER_PORT'] as Integer" do
-    old_value = ENV['SERVER_PORT']
-    begin
-      ENV['SERVER_PORT'] = nil
-      @cgi.server_port.should be_nil
+    it "returns ENV['SERVER_PORT'] as Integer" do
+      old_value = ENV['SERVER_PORT']
+      begin
+        ENV['SERVER_PORT'] = nil
+        @cgi.server_port.should == nil
 
-      ENV['SERVER_PORT'] = "3000"
-      @cgi.server_port.should eql(3000)
-    ensure
-      ENV['SERVER_PORT'] = old_value
+        ENV['SERVER_PORT'] = "3000"
+        @cgi.server_port.should.eql?(3000)
+      ensure
+        ENV['SERVER_PORT'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/server_protocol_spec.rb b/spec/ruby/library/cgi/queryextension/server_protocol_spec.rb
index f9dcf3c5b8..fdbcc2108f 100644
--- a/spec/ruby/library/cgi/queryextension/server_protocol_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/server_protocol_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#server_protocol" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#server_protocol" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['SERVER_PROTOCOL']" do
-    old_value, ENV['SERVER_PROTOCOL'] = ENV['SERVER_PROTOCOL'], "HTTP/1.1"
-    begin
-      @cgi.server_protocol.should == "HTTP/1.1"
-    ensure
-      ENV['SERVER_PROTOCOL'] = old_value
+    it "returns ENV['SERVER_PROTOCOL']" do
+      old_value, ENV['SERVER_PROTOCOL'] = ENV['SERVER_PROTOCOL'], "HTTP/1.1"
+      begin
+        @cgi.server_protocol.should == "HTTP/1.1"
+      ensure
+        ENV['SERVER_PROTOCOL'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/server_software_spec.rb b/spec/ruby/library/cgi/queryextension/server_software_spec.rb
index df349cdf2e..c5811a2268 100644
--- a/spec/ruby/library/cgi/queryextension/server_software_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/server_software_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#server_software" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#server_software" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['SERVER_SOFTWARE']" do
-    old_value, ENV['SERVER_SOFTWARE'] = ENV['SERVER_SOFTWARE'], "Server/1.0.0"
-    begin
-      @cgi.server_software.should == "Server/1.0.0"
-    ensure
-      ENV['SERVER_SOFTWARE'] = old_value
+    it "returns ENV['SERVER_SOFTWARE']" do
+      old_value, ENV['SERVER_SOFTWARE'] = ENV['SERVER_SOFTWARE'], "Server/1.0.0"
+      begin
+        @cgi.server_software.should == "Server/1.0.0"
+      ensure
+        ENV['SERVER_SOFTWARE'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/shared/has_key.rb b/spec/ruby/library/cgi/queryextension/shared/has_key.rb
index cfac5865fa..6231cb548e 100644
--- a/spec/ruby/library/cgi/queryextension/shared/has_key.rb
+++ b/spec/ruby/library/cgi/queryextension/shared/has_key.rb
@@ -12,8 +12,8 @@ describe :cgi_query_extension_has_key_p, shared: true do
   end
 
   it "returns true when the passed key exists in the HTTP Query" do
-    @cgi.send(@method, "one").should be_true
-    @cgi.send(@method, "two").should be_true
-    @cgi.send(@method, "three").should be_false
+    @cgi.send(@method, "one").should == true
+    @cgi.send(@method, "two").should == true
+    @cgi.send(@method, "three").should == false
   end
 end
diff --git a/spec/ruby/library/cgi/queryextension/user_agent_spec.rb b/spec/ruby/library/cgi/queryextension/user_agent_spec.rb
index ec5ef187dd..3240352ef6 100644
--- a/spec/ruby/library/cgi/queryextension/user_agent_spec.rb
+++ b/spec/ruby/library/cgi/queryextension/user_agent_spec.rb
@@ -1,22 +1,25 @@
 require_relative '../../../spec_helper'
-require 'cgi'
 
-describe "CGI::QueryExtension#user_agent" do
-  before :each do
-    ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
-    @cgi = CGI.new
-  end
+ruby_version_is ""..."4.0" do
+  require 'cgi'
 
-  after :each do
-    ENV['REQUEST_METHOD'] = @old_request_method
-  end
+  describe "CGI::QueryExtension#user_agent" do
+    before :each do
+      ENV['REQUEST_METHOD'], @old_request_method = "GET", ENV['REQUEST_METHOD']
+      @cgi = CGI.new
+    end
+
+    after :each do
+      ENV['REQUEST_METHOD'] = @old_request_method
+    end
 
-  it "returns ENV['HTTP_USER_AGENT']" do
-    old_value, ENV['HTTP_USER_AGENT'] = ENV['HTTP_USER_AGENT'], "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_2; de-de) AppleWebKit/527+ (KHTML, like Gecko) Version/3.1 Safari/525.13"
-    begin
-      @cgi.user_agent.should == "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_2; de-de) AppleWebKit/527+ (KHTML, like Gecko) Version/3.1 Safari/525.13"
-    ensure
-      ENV['HTTP_USER_AGENT'] = old_value
+    it "returns ENV['HTTP_USER_AGENT']" do
+      old_value, ENV['HTTP_USER_AGENT'] = ENV['HTTP_USER_AGENT'], "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_2; de-de) AppleWebKit/527+ (KHTML, like Gecko) Version/3.1 Safari/525.13"
+      begin
+        @cgi.user_agent.should == "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_2; de-de) AppleWebKit/527+ (KHTML, like Gecko) Version/3.1 Safari/525.13"
+      ensure
+        ENV['HTTP_USER_AGENT'] = old_value
+      end
     end
   end
 end
diff --git a/spec/ruby/library/cgi/rfc1123_date_spec.rb b/spec/ruby/library/cgi/rfc1123_date_spec.rb
index 6904eeabaa..636185f22c 100644
--- a/spec/ruby/library/cgi/rfc1123_date_spec.rb
+++ b/spec/ruby/library/cgi/rfc1123_date_spec.rb
@@ -1,10 +1,13 @@
 require_relative '../../spec_helper'
-require 'cgi'
 
-describe "CGI.rfc1123_date when passed Time" do
-  it "returns the passed Time formatted in RFC1123 ('Sat, 01 Dec 2007 15:56:42 GMT')" do
-    input = Time.at(1196524602)
-    expected = 'Sat, 01 Dec 2007 15:56:42 GMT'
-    CGI.rfc1123_date(input).should == expected
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+
+  describe "CGI.rfc1123_date when passed Time" do
+    it "returns the passed Time formatted in RFC1123 ('Sat, 01 Dec 2007 15:56:42 GMT')" do
+      input = Time.at(1196524602)
+      expected = 'Sat, 01 Dec 2007 15:56:42 GMT'
+      CGI.rfc1123_date(input).should == expected
+    end
   end
 end
diff --git a/spec/ruby/library/cgi/shared/http_header.rb b/spec/ruby/library/cgi/shared/http_header.rb
index b225b5925e..e739fed538 100644
--- a/spec/ruby/library/cgi/shared/http_header.rb
+++ b/spec/ruby/library/cgi/shared/http_header.rb
@@ -63,11 +63,11 @@ describe :cgi_http_header, shared: true do
       header.should == "Content-Type: text/plain; charset=UTF-8\r\n\r\n"
 
       header = @cgi.send(@method, "nph" => true)
-      header.should include("HTTP/1.0 200 OK\r\n")
-      header.should include("Date: ")
-      header.should include("Server: ")
-      header.should include("Connection: close\r\n")
-      header.should include("Content-Type: text/html\r\n")
+      header.should.include?("HTTP/1.0 200 OK\r\n")
+      header.should.include?("Date: ")
+      header.should.include?("Server: ")
+      header.should.include?("Connection: close\r\n")
+      header.should.include?("Content-Type: text/html\r\n")
 
       header = @cgi.send(@method, "status" => "OK")
       header.should == "Status: 200 OK\r\nContent-Type: text/html\r\n\r\n"
diff --git a/spec/ruby/library/cgi/unescapeElement_spec.rb b/spec/ruby/library/cgi/unescapeElement_spec.rb
index ae4d50b076..db83f0d2fb 100644
--- a/spec/ruby/library/cgi/unescapeElement_spec.rb
+++ b/spec/ruby/library/cgi/unescapeElement_spec.rb
@@ -1,5 +1,11 @@
 require_relative '../../spec_helper'
-require 'cgi'
+
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+end
+ruby_version_is "4.0" do
+  require 'cgi/escape'
+end
 
 describe "CGI.unescapeElement when passed String, elements, ..." do
   it "unescapes only the tags of the passed elements in the passed String" do
diff --git a/spec/ruby/library/cgi/unescapeHTML_spec.rb b/spec/ruby/library/cgi/unescapeHTML_spec.rb
index 46387d4f01..e43dcc83e5 100644
--- a/spec/ruby/library/cgi/unescapeHTML_spec.rb
+++ b/spec/ruby/library/cgi/unescapeHTML_spec.rb
@@ -1,5 +1,9 @@
 require_relative '../../spec_helper'
-require 'cgi'
+begin
+  require 'cgi/escape'
+rescue LoadError
+  require 'cgi'
+end
 
 describe "CGI.unescapeHTML" do
   it "unescapes '&amp; &lt; &gt; &quot;' to '& < > \"'" do
@@ -36,4 +40,9 @@ describe "CGI.unescapeHTML" do
     input = "fooooooo&#"
     CGI.unescapeHTML(input).should == input
   end
+
+  it "unescapes invalid encoding" do
+    input = "\xFF&"
+    CGI.unescapeHTML(input).should == input
+  end
 end
diff --git a/spec/ruby/library/cgi/unescapeURIComponent_spec.rb b/spec/ruby/library/cgi/unescapeURIComponent_spec.rb
new file mode 100644
index 0000000000..e0bf4b70e0
--- /dev/null
+++ b/spec/ruby/library/cgi/unescapeURIComponent_spec.rb
@@ -0,0 +1,128 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+end
+ruby_version_is "4.0" do
+  require 'cgi/escape'
+end
+
+describe "CGI.unescapeURIComponent" do
+  it "decodes any percent-encoded octets to their corresponding bytes according to RFC 3986" do
+    string = (0x00..0xff).map { |i| "%%%02x" % i }.join
+    expected = (0x00..0xff).map { |i| i.chr }.join.force_encoding(Encoding::UTF_8)
+    CGI.unescapeURIComponent(string).should == expected
+  end
+
+  it "disregards case of characters in a percent-encoding triplet" do
+    CGI.unescapeURIComponent("%CE%B2abc").should == "βabc"
+    CGI.unescapeURIComponent("%ce%b2ABC").should == "βABC"
+  end
+
+  it "leaves any non-percent-encoded characters as-is" do
+    string = "ABCDEFGHIJKLMNOPQRSTUVWXYZ:/?#[]@!$&'()*+,;=\t\x0D\xFFβᛉ▒90%"
+    decoded = CGI.unescapeURIComponent(string)
+    decoded.should == string
+    string.should_not.equal?(decoded)
+  end
+
+  it "leaves sequences which can't be a percent-encoded octet as-is" do
+    string = "%AZ%B"
+    decoded = CGI.unescapeURIComponent(string)
+    decoded.should == string
+    string.should_not.equal?(decoded)
+  end
+
+  it "creates a String with the specified target Encoding" do
+    string = CGI.unescapeURIComponent("%D2%3C%3CABC", Encoding::ISO_8859_1)
+    string.encoding.should == Encoding::ISO_8859_1
+    string.should == "Ò<<ABC".encode("ISO-8859-1")
+  end
+
+  it "accepts a string name of an Encoding" do
+    CGI.unescapeURIComponent("%D2%3C%3CABC", "ISO-8859-1").should == "Ò<<ABC".encode("ISO-8859-1")
+  end
+
+  it "raises ArgumentError if specified encoding is unknown" do
+    -> { CGI.unescapeURIComponent("ABC", "ISO-JOKE-1") }.should.raise(ArgumentError, "unknown encoding name - ISO-JOKE-1")
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "uses CGI.accept_charset as the default target encoding" do
+      original_charset = CGI.accept_charset
+      CGI.accept_charset = "ISO-8859-1"
+      decoded = CGI.unescapeURIComponent("%D2%3C%3CABC")
+      decoded.should == "Ò<<ABC".encode("ISO-8859-1")
+      decoded.encoding.should == Encoding::ISO_8859_1
+    ensure
+      CGI.accept_charset = original_charset
+    end
+
+    it "has CGI.accept_charset as UTF-8 by default" do
+      decoded = CGI.unescapeURIComponent("%CE%B2ABC")
+      decoded.should == "βABC"
+      decoded.encoding.should == Encoding::UTF_8
+    end
+  end
+
+  ruby_version_is "4.0" do
+    # "cgi/escape" does not have methods to access @@accept_charset.
+    # Full "cgi" gem provides them, allowing to possibly change it.
+    it "uses CGI's @@accept_charset as the default target encoding" do
+      original_charset = CGI.class_variable_get(:@@accept_charset)
+      CGI.class_variable_set(:@@accept_charset, "ISO-8859-1")
+      decoded = CGI.unescapeURIComponent("%D2%3C%3CABC")
+      decoded.should == "Ò<<ABC".encode("ISO-8859-1")
+      decoded.encoding.should == Encoding::ISO_8859_1
+    ensure
+      CGI.class_variable_set(:@@accept_charset, original_charset)
+    end
+
+    it "has CGI's @@accept_charset as UTF-8 by default" do
+      decoded = CGI.unescapeURIComponent("%CE%B2ABC")
+      decoded.should == "βABC"
+      decoded.encoding.should == Encoding::UTF_8
+    end
+  end
+
+  context "when source string specifies octets invalid in target encoding" do
+    it "uses source string's encoding" do
+      string = "%A2%A6%A3".encode(Encoding::SHIFT_JIS)
+      decoded = CGI.unescapeURIComponent(string, Encoding::US_ASCII)
+      decoded.encoding.should == Encoding::SHIFT_JIS
+      decoded.should == "｢ｦ｣".encode(Encoding::SHIFT_JIS)
+      decoded.valid_encoding?.should == true
+    end
+
+    it "uses source string's encoding even if it's also invalid" do
+      string = "%FF".encode(Encoding::US_ASCII)
+      decoded = CGI.unescapeURIComponent(string, Encoding::SHIFT_JIS)
+      decoded.encoding.should == Encoding::US_ASCII
+      decoded.should == "\xFF".dup.force_encoding(Encoding::US_ASCII)
+      decoded.valid_encoding?.should == false
+    end
+  end
+
+  it "decodes an empty string as an empty string with target encoding" do
+    string = "".encode(Encoding::BINARY)
+    decoded = CGI.unescapeURIComponent(string, "UTF-8")
+    decoded.should == ""
+    decoded.encoding.should == Encoding::UTF_8
+    string.should_not.equal?(decoded)
+  end
+
+  it "raises a TypeError with nil" do
+    -> {
+      CGI.unescapeURIComponent(nil)
+    }.should.raise(TypeError, "no implicit conversion of nil into String")
+  end
+
+  it "uses implicit type conversion to String" do
+    object = Object.new
+    def object.to_str
+      "a%20b"
+    end
+
+    CGI.unescapeURIComponent(object).should == "a b"
+  end
+end
diff --git a/spec/ruby/library/cgi/unescape_spec.rb b/spec/ruby/library/cgi/unescape_spec.rb
index db4834e7e8..aa731b9367 100644
--- a/spec/ruby/library/cgi/unescape_spec.rb
+++ b/spec/ruby/library/cgi/unescape_spec.rb
@@ -1,6 +1,12 @@
 # -*- encoding: utf-8 -*-
 require_relative '../../spec_helper'
-require 'cgi'
+
+ruby_version_is ""..."4.0" do
+  require 'cgi'
+end
+ruby_version_is "4.0" do
+  require 'cgi/escape'
+end
 
 describe "CGI.unescape" do
   it "url-decodes the passed argument" do
@@ -8,8 +14,8 @@ describe "CGI.unescape" do
     expected = " !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
     CGI.unescape(input).should == expected
 
-    input    = 'http%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
-    expected = "http://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
+    input    = 'https%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
+    expected = "https://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
     CGI.unescape(input).should == expected
   end
 end
diff --git a/spec/ruby/library/cmath/math/acos_spec.rb b/spec/ruby/library/cmath/math/acos_spec.rb
deleted file mode 100644
index 2e9104f835..0000000000
--- a/spec/ruby/library/cmath/math/acos_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/acos'
-
-  describe "Math#acos" do
-    it_behaves_like :complex_math_acos, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:acos)
-    end
-  end
-
-  describe "Math.acos" do
-    it_behaves_like :complex_math_acos, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/acosh_spec.rb b/spec/ruby/library/cmath/math/acosh_spec.rb
deleted file mode 100644
index 809112f6c0..0000000000
--- a/spec/ruby/library/cmath/math/acosh_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/acosh'
-
-  describe "Math#acosh" do
-    it_behaves_like :complex_math_acosh, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:acosh)
-    end
-  end
-
-  describe "Math.acosh" do
-    it_behaves_like :complex_math_acosh, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/asin_spec.rb b/spec/ruby/library/cmath/math/asin_spec.rb
deleted file mode 100644
index 4ac588ebd2..0000000000
--- a/spec/ruby/library/cmath/math/asin_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/asin'
-
-  describe "Math#asin" do
-    it_behaves_like :complex_math_asin, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:asin)
-    end
-  end
-
-  describe "Math.asin" do
-    it_behaves_like :complex_math_asin, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/asinh_spec.rb b/spec/ruby/library/cmath/math/asinh_spec.rb
deleted file mode 100644
index 7d8b397a04..0000000000
--- a/spec/ruby/library/cmath/math/asinh_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/asinh'
-
-  describe "Math#asinh" do
-    it_behaves_like :complex_math_asinh, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:asinh)
-    end
-  end
-
-  describe "Math.asinh" do
-    it_behaves_like :complex_math_asinh, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/atan2_spec.rb b/spec/ruby/library/cmath/math/atan2_spec.rb
deleted file mode 100644
index 1a9b7d7607..0000000000
--- a/spec/ruby/library/cmath/math/atan2_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/atan2'
-
-  describe "Math#atan2" do
-    it_behaves_like :complex_math_atan2, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:atan2)
-    end
-  end
-
-  describe "Math.atan2" do
-    it_behaves_like :complex_math_atan2, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/atan_spec.rb b/spec/ruby/library/cmath/math/atan_spec.rb
deleted file mode 100644
index b0171081a6..0000000000
--- a/spec/ruby/library/cmath/math/atan_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/atan'
-
-  describe "Math#atan" do
-    it_behaves_like :complex_math_atan, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:atan)
-    end
-  end
-
-  describe "Math.atan" do
-    it_behaves_like :complex_math_atan, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/atanh_spec.rb b/spec/ruby/library/cmath/math/atanh_spec.rb
deleted file mode 100644
index 6b22c6c9e4..0000000000
--- a/spec/ruby/library/cmath/math/atanh_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative '../../../fixtures/math/common'
-  require_relative '../../../shared/math/atanh'
-  require_relative 'shared/atanh'
-
-  describe "Math#atanh" do
-    it_behaves_like :math_atanh_base, :atanh, IncludesMath.new
-    it_behaves_like :complex_math_atanh_complex, :atanh, IncludesMath.new
-
-    it_behaves_like :math_atanh_private, :atanh, IncludesMath.new
-  end
-
-  describe "Math.atanh" do
-    it_behaves_like :math_atanh_base, :atanh, CMath
-    it_behaves_like :complex_math_atanh_complex, :atanh, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/cos_spec.rb b/spec/ruby/library/cmath/math/cos_spec.rb
deleted file mode 100644
index 3f097bcb3b..0000000000
--- a/spec/ruby/library/cmath/math/cos_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/cos'
-
-  describe "Math#cos" do
-    it_behaves_like :complex_math_cos, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:cos)
-    end
-  end
-
-  describe "Math.cos" do
-    it_behaves_like :complex_math_cos, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/cosh_spec.rb b/spec/ruby/library/cmath/math/cosh_spec.rb
deleted file mode 100644
index 197f899981..0000000000
--- a/spec/ruby/library/cmath/math/cosh_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/cosh'
-
-  describe "Math#cosh" do
-    it_behaves_like :complex_math_cosh, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:cosh)
-    end
-  end
-
-  describe "Math.cosh" do
-    it_behaves_like :complex_math_cosh, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/exp_spec.rb b/spec/ruby/library/cmath/math/exp_spec.rb
deleted file mode 100644
index eef2ec3129..0000000000
--- a/spec/ruby/library/cmath/math/exp_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/exp'
-
-  describe "Math#exp" do
-    it_behaves_like :complex_math_exp, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:exp)
-    end
-  end
-
-  describe "Math.exp" do
-    it_behaves_like :complex_math_exp, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/fixtures/classes.rb b/spec/ruby/library/cmath/math/fixtures/classes.rb
deleted file mode 100644
index 443c1a9ace..0000000000
--- a/spec/ruby/library/cmath/math/fixtures/classes.rb
+++ /dev/null
@@ -1,4 +0,0 @@
-require 'cmath'
-class IncludesMath
-  include CMath
-end
diff --git a/spec/ruby/library/cmath/math/log10_spec.rb b/spec/ruby/library/cmath/math/log10_spec.rb
deleted file mode 100644
index 603bbb1457..0000000000
--- a/spec/ruby/library/cmath/math/log10_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/log10'
-
-  describe "Math#log10" do
-    it_behaves_like :complex_math_log10, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:log10)
-    end
-  end
-
-  describe "Math.log10" do
-    it_behaves_like :complex_math_log10, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/log_spec.rb b/spec/ruby/library/cmath/math/log_spec.rb
deleted file mode 100644
index b4da781323..0000000000
--- a/spec/ruby/library/cmath/math/log_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/log'
-
-  describe "Math#log" do
-    it_behaves_like :complex_math_log, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:log)
-    end
-  end
-
-  describe "Math.log" do
-    it_behaves_like :complex_math_log, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/acos.rb b/spec/ruby/library/cmath/math/shared/acos.rb
deleted file mode 100644
index 65637fa838..0000000000
--- a/spec/ruby/library/cmath/math/shared/acos.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_acos, shared: true do
-  it "returns the arccosine of the passed argument" do
-    @object.send(:acos, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:acos, 0).should be_close(1.5707963267949, TOLERANCE)
-    @object.send(:acos, -1).should be_close(Math::PI,TOLERANCE)
-  end
-
-  it "returns the arccosine for Complex numbers" do
-    @object.send(:acos, Complex(3, 4)).should be_close(Complex(0.93681246115572, -2.30550903124348), TOLERANCE)
-  end
-
-  it "returns the arccosine for numbers greater than 1.0 as a Complex number" do
-    @object.send(:acos, 1.0001).should be_close(Complex(0.0, 0.0141420177752494), TOLERANCE)
-  end
-
-  it "returns the arccosine for numbers less than -1.0 as a Complex number" do
-    @object.send(:acos, -1.0001).should be_close(Complex(3.14159265358979, -0.0141420177752495), TOLERANCE)
-  end
-end
-
-describe :complex_math_acos_bang, shared: true do
-  it "returns the arccosine of the argument" do
-    @object.send(:acos!, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:acos!, 0).should be_close(1.5707963267949, TOLERANCE)
-    @object.send(:acos!, -1).should be_close(Math::PI,TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:acos!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-
-  it "raises an Errno::EDOM for numbers greater than 1.0" do
-    -> { @object.send(:acos!, 1.0001) }.should raise_error(Errno::EDOM)
-  end
-
-  it "raises an Errno::EDOM for numbers less than -1.0" do
-    -> { @object.send(:acos!, -1.0001) }.should raise_error(Errno::EDOM)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/acosh.rb b/spec/ruby/library/cmath/math/shared/acosh.rb
deleted file mode 100644
index 285b0b823f..0000000000
--- a/spec/ruby/library/cmath/math/shared/acosh.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_acosh, shared: true do
-  it "returns the principle value of the inverse hyperbolic cosine of the argument" do
-    @object.send(:acosh, 14.2).should be_close(3.345146999647, TOLERANCE)
-    @object.send(:acosh, 1.0).should be_close(0.0, TOLERANCE)
-  end
-
-  it "returns the principle value of the inverse hyperbolic cosine for numbers less than 1.0 as a Complex number" do
-    @object.send(:acosh, 1.0 - TOLERANCE).should be_close(Complex(0.0, 0.00774598605746135), TOLERANCE)
-    @object.send(:acosh, 0).should be_close(Complex(0.0, 1.5707963267949), TOLERANCE)
-    @object.send(:acosh, -1.0).should be_close(Complex(0.0, 3.14159265358979), TOLERANCE)
-  end
-
-  it "returns the principle value of the inverse hyperbolic cosine for Complex numbers" do
-    @object.send(:acosh, Complex(3, 4))
-    @object.send(:acosh, Complex(3, 4)).imaginary.should be_close(0.93681246115572, TOLERANCE)
-    @object.send(:acosh, Complex(3, 4)).real.should be_close(2.305509031243477, TOLERANCE)
-  end
-end
-
-describe :complex_math_acosh_bang, shared: true do
-  it "returns the principle value of the inverse hyperbolic cosine of the argument" do
-    @object.send(:acosh!, 14.2).should be_close(3.345146999647, TOLERANCE)
-    @object.send(:acosh!, 1.0).should be_close(0.0, TOLERANCE)
-  end
-
-  it "raises Errno::EDOM for numbers less than 1.0" do
-    -> { @object.send(:acosh!, 1.0 - TOLERANCE) }.should raise_error(Errno::EDOM)
-    -> { @object.send(:acosh!, 0) }.should raise_error(Errno::EDOM)
-    -> { @object.send(:acosh!, -1.0) }.should raise_error(Errno::EDOM)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:acosh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/asin.rb b/spec/ruby/library/cmath/math/shared/asin.rb
deleted file mode 100644
index 91fed7aa06..0000000000
--- a/spec/ruby/library/cmath/math/shared/asin.rb
+++ /dev/null
@@ -1,47 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_asin, shared: true do
-  it "returns the arcsine of the argument" do
-    @object.send(:asin, 1).should be_close(Math::PI/2, TOLERANCE)
-    @object.send(:asin, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:asin, -1).should be_close(-Math::PI/2, TOLERANCE)
-    @object.send(:asin, 0.25).should be_close(0.252680255142079, TOLERANCE)
-    @object.send(:asin, 0.50).should be_close(0.523598775598299, TOLERANCE)
-    @object.send(:asin, 0.75).should be_close(0.8480620789814816,TOLERANCE)
-  end
-
-  it "returns the arcsine for Complex numbers" do
-    @object.send(:asin, Complex(3, 4)).should be_close(Complex(0.633983865639174, 2.30550903124347), TOLERANCE)
-  end
-
-  it "returns a Complex number when the argument is greater than 1.0" do
-    @object.send(:asin, 1.0001).should be_close(Complex(1.5707963267949, -0.0141420177752494), TOLERANCE)
-  end
-
-  it "returns a Complex number when the argument is less than -1.0" do
-    @object.send(:asin, -1.0001).should be_close(Complex(-1.5707963267949, 0.0141420177752494), TOLERANCE)
-  end
-end
-
-describe :complex_math_asin_bang, shared: true do
-  it "returns the arcsine of the argument" do
-    @object.send(:asin!, 1).should be_close(Math::PI/2, TOLERANCE)
-    @object.send(:asin!, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:asin!, -1).should be_close(-Math::PI/2, TOLERANCE)
-    @object.send(:asin!, 0.25).should be_close(0.252680255142079, TOLERANCE)
-    @object.send(:asin!, 0.50).should be_close(0.523598775598299, TOLERANCE)
-    @object.send(:asin!, 0.75).should be_close(0.8480620789814816,TOLERANCE)
-  end
-
-  it "raises an Errno::EDOM if the argument is greater than 1.0" do
-    -> { @object.send(:asin!, 1.0001) }.should raise_error( Errno::EDOM)
-  end
-
-  it "raises an Errno::EDOM if the argument is less than -1.0" do
-    -> { @object.send(:asin!, -1.0001) }.should raise_error( Errno::EDOM)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:asin!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/asinh.rb b/spec/ruby/library/cmath/math/shared/asinh.rb
deleted file mode 100644
index b4ddd3a22e..0000000000
--- a/spec/ruby/library/cmath/math/shared/asinh.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_asinh, shared: true do
-  it "returns the inverse hyperbolic sin of the argument" do
-    @object.send(:asinh, 1.5).should be_close(1.19476321728711, TOLERANCE)
-    @object.send(:asinh, -2.97).should be_close(-1.8089166921397, TOLERANCE)
-    @object.send(:asinh, 0.0).should == 0.0
-    @object.send(:asinh, -0.0).should == -0.0
-    @object.send(:asinh, 1.05367e-08).should be_close(1.05367e-08, TOLERANCE)
-    @object.send(:asinh, -1.05367e-08).should be_close(-1.05367e-08, TOLERANCE)
-  end
-
-  it "returns the inverse hyperbolic sin for Complex numbers" do
-    @object.send(:asinh, Complex(3, 4)).should be_close(Complex(2.29991404087927, 0.917616853351479), TOLERANCE)
-    @object.send(:asinh, Complex(3.5, -4)).should be_close(Complex(2.36263337274419, -0.843166327537659), TOLERANCE)
-  end
-end
-
-describe :complex_math_asinh_bang, shared: true do
-  it "returns the inverse hyperbolic sin of the argument" do
-    @object.send(:asinh!, 1.5).should be_close(1.19476321728711, TOLERANCE)
-    @object.send(:asinh!, -2.97).should be_close(-1.8089166921397, TOLERANCE)
-    @object.send(:asinh!, 0.0).should == 0.0
-    @object.send(:asinh!, -0.0).should == -0.0
-    @object.send(:asinh!, 1.05367e-08).should be_close(1.05367e-08, TOLERANCE)
-    @object.send(:asinh!, -1.05367e-08).should be_close(-1.05367e-08, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:asinh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/atan.rb b/spec/ruby/library/cmath/math/shared/atan.rb
deleted file mode 100644
index 63a496e841..0000000000
--- a/spec/ruby/library/cmath/math/shared/atan.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_atan, shared: true do
-  it "returns the arctangent of the argument" do
-    @object.send(:atan, 1).should be_close(Math::PI/4, TOLERANCE)
-    @object.send(:atan, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:atan, -1).should be_close(-Math::PI/4, TOLERANCE)
-    @object.send(:atan, 0.25).should be_close(0.244978663126864, TOLERANCE)
-    @object.send(:atan, 0.50).should be_close(0.463647609000806, TOLERANCE)
-    @object.send(:atan, 0.75).should be_close(0.643501108793284, TOLERANCE)
-  end
-
-  it "returns the arctangent for Complex numbers" do
-    @object.send(:atan, Complex(3, 4)).should be_close(Complex(1.44830699523146, 0.158997191679999), TOLERANCE)
-    @object.send(:atan, Complex(3.5, -4)).should be_close(Complex(1.44507428165589, -0.140323762363786), TOLERANCE)
-  end
-end
-
-describe :complex_math_atan_bang, shared: true do
-  it "returns the arctangent of the argument" do
-    @object.send(:atan!, 1).should be_close(Math::PI/4, TOLERANCE)
-    @object.send(:atan!, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:atan!, -1).should be_close(-Math::PI/4, TOLERANCE)
-    @object.send(:atan!, 0.25).should be_close(0.244978663126864, TOLERANCE)
-    @object.send(:atan!, 0.50).should be_close(0.463647609000806, TOLERANCE)
-    @object.send(:atan!, 0.75).should be_close(0.643501108793284, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:atan!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/atan2.rb b/spec/ruby/library/cmath/math/shared/atan2.rb
deleted file mode 100644
index 6d89423924..0000000000
--- a/spec/ruby/library/cmath/math/shared/atan2.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_atan2, shared: true do
-  it "returns the arc tangent of the passed arguments" do
-    @object.send(:atan2, 4.2, 0.3).should be_close(1.49948886200961, TOLERANCE)
-    @object.send(:atan2, 0.0, 1.0).should be_close(0.0, TOLERANCE)
-    @object.send(:atan2, -9.1, 3.2).should be_close(-1.23265379809025, TOLERANCE)
-    @object.send(:atan2, 7.22, -3.3).should be_close(1.99950888779256, TOLERANCE)
-  end
-
-  it "returns the arc tangent for two Complex numbers" do
-    CMath.atan2(Complex(3, 4), Complex(3.5, -4)).should be_close(Complex(-0.641757436698881, 1.10829873031207), TOLERANCE)
-  end
-
-  it "returns the arc tangent for Complex and real numbers" do
-    CMath.atan2(Complex(3, 4), -7).should be_close(Complex(2.61576754731561, -0.494290673139855), TOLERANCE)
-    CMath.atan2(5, Complex(3.5, -4)).should be_close(Complex(0.739102348493673, 0.487821626522923), TOLERANCE)
-  end
-end
-
-describe :complex_math_atan2_bang, shared: true do
-  it "returns the arc tangent of the passed arguments" do
-    @object.send(:atan2!, 4.2, 0.3).should be_close(1.49948886200961, TOLERANCE)
-    @object.send(:atan2!, 0.0, 1.0).should be_close(0.0, TOLERANCE)
-    @object.send(:atan2!, -9.1, 3.2).should be_close(-1.23265379809025, TOLERANCE)
-    @object.send(:atan2!, 7.22, -3.3).should be_close(1.99950888779256, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:atan2!, Complex(4, 5), Complex(4, 5)) }.should raise_error(TypeError)
-    -> { @object.send(:atan2!, 4, Complex(4, 5)) }.should raise_error(TypeError)
-    -> { @object.send(:atan2!, Complex(4, 5), 5) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/atanh.rb b/spec/ruby/library/cmath/math/shared/atanh.rb
deleted file mode 100644
index ae80e61bec..0000000000
--- a/spec/ruby/library/cmath/math/shared/atanh.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_atanh_complex, shared: true do
-  it "returns the inverse hyperbolic tangent as a Complex number for arguments greater than 1.0" do
-    value = Complex(18.36840028483855, 1.5707963267948966)
-    @object.send(@method, 1.0 + Float::EPSILON).should be_close(value, TOLERANCE)
-
-    value = Complex(0.100335347731076, 1.5707963267949)
-    @object.send(@method, 10).should be_close(value, TOLERANCE)
-  end
-
-  it "returns the inverse hyperbolic tangent as a Complex number for arguments greater than 1.0" do
-    value = Complex(-18.36840028483855, 1.5707963267948966)
-    @object.send(@method, -1.0 - Float::EPSILON).should be_close(value, TOLERANCE)
-
-    value = Complex(0.100335347731076, 1.5707963267949)
-    @object.send(@method, 10).should be_close(value, TOLERANCE)
-  end
-
-  it "returns the inverse hyperbolic tangent for Complex numbers" do
-    value = Complex(0.117500907311434, 1.40992104959658)
-    @object.send(@method, Complex(3, 4)).should be_close(value, TOLERANCE)
-  end
-end
-
-describe :complex_math_atanh_no_complex, shared: true do
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:atanh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/cos.rb b/spec/ruby/library/cmath/math/shared/cos.rb
deleted file mode 100644
index 31cb5ab1e5..0000000000
--- a/spec/ruby/library/cmath/math/shared/cos.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_cos, shared: true do
-  it "returns the cosine of the argument expressed in radians" do
-    @object.send(:cos, CMath::PI).should be_close(-1.0, TOLERANCE)
-    @object.send(:cos, 0).should be_close(1.0, TOLERANCE)
-    @object.send(:cos, CMath::PI/2).should be_close(0.0, TOLERANCE)
-    @object.send(:cos, 3*Math::PI/2).should be_close(0.0, TOLERANCE)
-    @object.send(:cos, 2*Math::PI).should be_close(1.0, TOLERANCE)
-  end
-
-  it "returns the cosine for Complex numbers" do
-    @object.send(:cos, Complex(0, CMath::PI)).should be_close(Complex(11.5919532755215, 0.0), TOLERANCE)
-    @object.send(:cos, Complex(3, 4)).should be_close(Complex(-27.0349456030742, -3.85115333481178), TOLERANCE)
-  end
-end
-
-describe :complex_math_cos_bang, shared: true do
-  it "returns the cosine of the argument expressed in radians" do
-    @object.send(:cos!, CMath::PI).should be_close(-1.0, TOLERANCE)
-    @object.send(:cos!, 0).should be_close(1.0, TOLERANCE)
-    @object.send(:cos!, CMath::PI/2).should be_close(0.0, TOLERANCE)
-    @object.send(:cos!, 3*Math::PI/2).should be_close(0.0, TOLERANCE)
-    @object.send(:cos!, 2*Math::PI).should be_close(1.0, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:cos!, Complex(3, 4)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/cosh.rb b/spec/ruby/library/cmath/math/shared/cosh.rb
deleted file mode 100644
index 7cf561c985..0000000000
--- a/spec/ruby/library/cmath/math/shared/cosh.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_cosh, shared: true do
-  it "returns the hyperbolic cosine of the passed argument" do
-    @object.send(:cosh, 0.0).should == 1.0
-    @object.send(:cosh, -0.0).should == 1.0
-    @object.send(:cosh, 1.5).should be_close(2.35240961524325, TOLERANCE)
-    @object.send(:cosh, -2.99).should be_close(9.96798496414416, TOLERANCE)
-  end
-
-  it "returns the hyperbolic cosine for Complex numbers" do
-    @object.send(:cosh, Complex(0, CMath::PI)).should be_close(Complex(-1.0, 0.0), TOLERANCE)
-    @object.send(:cosh, Complex(3, 4)).should be_close(Complex(-6.58066304055116, -7.58155274274654), TOLERANCE)
-  end
-end
-
-describe :complex_math_cosh_bang, shared: true do
-  it "returns the hyperbolic cosine of the passed argument" do
-    @object.send(:cosh!, 0.0).should == 1.0
-    @object.send(:cosh!, -0.0).should == 1.0
-    @object.send(:cosh!, 1.5).should be_close(2.35240961524325, TOLERANCE)
-    @object.send(:cosh!, -2.99).should be_close(9.96798496414416, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:cosh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/exp.rb b/spec/ruby/library/cmath/math/shared/exp.rb
deleted file mode 100644
index 6715ac63d3..0000000000
--- a/spec/ruby/library/cmath/math/shared/exp.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_exp, shared: true do
-  it "returns the base-e exponential of the passed argument" do
-    @object.send(:exp, 0.0).should == 1.0
-    @object.send(:exp, -0.0).should == 1.0
-    @object.send(:exp, -1.8).should be_close(0.165298888221587, TOLERANCE)
-    @object.send(:exp, 1.25).should be_close(3.49034295746184, TOLERANCE)
-  end
-
-  it "returns the base-e exponential for Complex numbers" do
-    @object.send(:exp, Complex(0, 0)).should == Complex(1.0, 0.0)
-    @object.send(:exp, Complex(1, 3)).should be_close(Complex(-2.69107861381979, 0.383603953541131), TOLERANCE)
-  end
-end
-
-describe :complex_math_exp_bang, shared: true do
-  it "returns the base-e exponential of the passed argument" do
-    @object.send(:exp!, 0.0).should == 1.0
-    @object.send(:exp!, -0.0).should == 1.0
-    @object.send(:exp!, -1.8).should be_close(0.165298888221587, TOLERANCE)
-    @object.send(:exp!, 1.25).should be_close(3.49034295746184, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:exp!, Complex(1, 3)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/log.rb b/spec/ruby/library/cmath/math/shared/log.rb
deleted file mode 100644
index 4b23e8c5f2..0000000000
--- a/spec/ruby/library/cmath/math/shared/log.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_log, shared: true do
-  it "returns the natural logarithm of the passed argument" do
-    @object.send(:log, 0.0001).should be_close(-9.21034037197618, TOLERANCE)
-    @object.send(:log, 0.000000000001e-15).should be_close(-62.1697975108392, TOLERANCE)
-    @object.send(:log, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:log, 10).should be_close( 2.30258509299405, TOLERANCE)
-    @object.send(:log, 10e15).should be_close(36.8413614879047, TOLERANCE)
-  end
-
-  it "returns the natural logarithm for Complex numbers" do
-    @object.send(:log, Complex(3, 4)).should be_close(Complex(1.6094379124341, 0.927295218001612), TOLERANCE)
-    @object.send(:log, Complex(-3, 4)).should be_close(Complex(1.6094379124341, 2.21429743558818), TOLERANCE)
-  end
-
-  it "returns the natural logarithm for negative numbers as a Complex number" do
-    @object.send(:log, -10).should be_close(Complex(2.30258509299405, 3.14159265358979), TOLERANCE)
-    @object.send(:log, -20).should be_close(Complex(2.99573227355399, 3.14159265358979), TOLERANCE)
-  end
-end
-
-describe :complex_math_log_bang, shared: true do
-  it "returns the natural logarithm of the argument" do
-    @object.send(:log!, 0.0001).should be_close(-9.21034037197618, TOLERANCE)
-    @object.send(:log!, 0.000000000001e-15).should be_close(-62.1697975108392, TOLERANCE)
-    @object.send(:log!, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:log!, 10).should be_close( 2.30258509299405, TOLERANCE)
-    @object.send(:log!, 10e15).should be_close(36.8413614879047, TOLERANCE)
-  end
-
-  it "raises an Errno::EDOM if the argument is less than 0" do
-    -> { @object.send(:log!, -10) }.should raise_error(Errno::EDOM)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:log!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/log10.rb b/spec/ruby/library/cmath/math/shared/log10.rb
deleted file mode 100644
index f49934d958..0000000000
--- a/spec/ruby/library/cmath/math/shared/log10.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_log10, shared: true do
-  it "returns the base-10 logarithm of the passed argument" do
-    @object.send(:log10, 0.0001).should be_close(-4.0, TOLERANCE)
-    @object.send(:log10, 0.000000000001e-15).should be_close(-27.0, TOLERANCE)
-    @object.send(:log10, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:log10, 10).should be_close(1.0, TOLERANCE)
-    @object.send(:log10, 10e15).should be_close(16.0, TOLERANCE)
-  end
-
-  it "returns the base-10 logarithm for Complex numbers" do
-    @object.send(:log10, Complex(3, 4)).should be_close(Complex(0.698970004336019, 0.402719196273373), TOLERANCE)
-    @object.send(:log10, Complex(-3, 4)).should be_close(Complex(0.698970004336019, 0.961657157568468), TOLERANCE)
-  end
-
-  # BUG: does not work correctly, because Math#log10
-  # does not check for negative values
-  #it "returns the base-10 logarithm for negative numbers as a Complex number" do
-  #  @object.send(:log10, -10).should be_close(Complex(2.30258509299405, 3.14159265358979), TOLERANCE)
-  #  @object.send(:log10, -20).should be_close(Complex(2.99573227355399, 3.14159265358979), TOLERANCE)
-  #end
-end
-
-describe :complex_math_log10_bang, shared: true do
-  it "returns the base-10 logarithm of the argument" do
-    @object.send(:log10!, 0.0001).should be_close(-4.0, TOLERANCE)
-    @object.send(:log10!, 0.000000000001e-15).should be_close(-27.0, TOLERANCE)
-    @object.send(:log10!, 1).should be_close(0.0, TOLERANCE)
-    @object.send(:log10!, 10).should be_close(1.0, TOLERANCE)
-    @object.send(:log10!, 10e15).should be_close(16.0, TOLERANCE)
-  end
-
-  it "raises an Errno::EDOM when the passed argument is negative" do
-    -> { @object.send(:log10!, -10) }.should raise_error(Errno::EDOM)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:log10!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/sin.rb b/spec/ruby/library/cmath/math/shared/sin.rb
deleted file mode 100644
index 1cb1b29cda..0000000000
--- a/spec/ruby/library/cmath/math/shared/sin.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_sin, shared: true do
-  it "returns the sine of the passed argument expressed in radians" do
-    @object.send(:sin, CMath::PI).should be_close(0.0, TOLERANCE)
-    @object.send(:sin, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:sin, CMath::PI/2).should be_close(1.0, TOLERANCE)
-    @object.send(:sin, 3*Math::PI/2).should be_close(-1.0, TOLERANCE)
-    @object.send(:sin, 2*Math::PI).should be_close(0.0, TOLERANCE)
-  end
-
-  it "returns the sine for Complex numbers" do
-    @object.send(:sin, Complex(0, CMath::PI)).should be_close(Complex(0.0, 11.5487393572577), TOLERANCE)
-    @object.send(:sin, Complex(3, 4)).should be_close(Complex(3.85373803791938, -27.0168132580039), TOLERANCE)
-  end
-end
-
-describe :complex_math_sin_bang, shared: true do
-  it "returns the sine of the passed argument expressed in radians" do
-    @object.send(:sin!, CMath::PI).should be_close(0.0, TOLERANCE)
-    @object.send(:sin!, 0).should be_close(0.0, TOLERANCE)
-    @object.send(:sin!, CMath::PI/2).should be_close(1.0, TOLERANCE)
-    @object.send(:sin!, 3*Math::PI/2).should be_close(-1.0, TOLERANCE)
-    @object.send(:sin!, 2*Math::PI).should be_close(0.0, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:sin!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/sinh.rb b/spec/ruby/library/cmath/math/shared/sinh.rb
deleted file mode 100644
index de80a376da..0000000000
--- a/spec/ruby/library/cmath/math/shared/sinh.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_sinh, shared: true do
-  it "returns the hyperbolic sin of the argument" do
-    @object.send(:sinh, 0.0).should == 0.0
-    @object.send(:sinh, -0.0).should == 0.0
-    @object.send(:sinh, 1.5).should be_close(2.12927945509482, TOLERANCE)
-    @object.send(:sinh, -2.8).should be_close(-8.19191835423591, TOLERANCE)
-  end
-
-  it "returns the hyperbolic sin for Complex numbers" do
-    @object.send(:sinh, Complex(0, CMath::PI)).should be_close(Complex(-0.0, 1.22464679914735e-16), TOLERANCE)
-    @object.send(:sinh, Complex(3, 4)).should be_close(Complex(-6.548120040911, -7.61923172032141), TOLERANCE)
-  end
-end
-
-describe :complex_math_sinh_bang, shared: true do
-  it "returns the hyperbolic sin of the argument" do
-    @object.send(:sinh!, 0.0).should == 0.0
-    @object.send(:sinh!, -0.0).should == 0.0
-    @object.send(:sinh!, 1.5).should be_close(2.12927945509482, TOLERANCE)
-    @object.send(:sinh!, -2.8).should be_close(-8.19191835423591, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:sinh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/sqrt.rb b/spec/ruby/library/cmath/math/shared/sqrt.rb
deleted file mode 100644
index 23b1ba48ff..0000000000
--- a/spec/ruby/library/cmath/math/shared/sqrt.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_sqrt, shared: true do
-  it "returns the square root for positive numbers" do
-    @object.send(:sqrt, 4).should == 2
-    @object.send(:sqrt, 19.36).should == 4.4
-  end
-
-  it "returns the square root for negative numbers" do
-    @object.send(:sqrt, -4).should == Complex(0, 2.0)
-    @object.send(:sqrt, -19.36).should == Complex(0, 4.4)
-  end
-
-  it "returns the square root for Complex numbers" do
-    @object.send(:sqrt, Complex(4, 5)).should be_close(Complex(2.2806933416653, 1.09615788950152), TOLERANCE)
-    @object.send(:sqrt, Complex(4, -5)).should be_close(Complex(2.2806933416653, -1.09615788950152), TOLERANCE)
-  end
-end
-
-describe :complex_math_sqrt_bang, shared: true do
-  it "returns the square root for positive numbers" do
-    @object.send(:sqrt!, 4).should == 2
-    @object.send(:sqrt!, 19.36).should == 4.4
-  end
-
-  it "raises Errno::EDOM when the passed argument is negative" do
-    -> { @object.send(:sqrt!, -4) }.should raise_error(Errno::EDOM)
-    -> { @object.send(:sqrt!, -19.36) }.should raise_error(Errno::EDOM)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:sqrt!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/tan.rb b/spec/ruby/library/cmath/math/shared/tan.rb
deleted file mode 100644
index 9022c84fc9..0000000000
--- a/spec/ruby/library/cmath/math/shared/tan.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_tan, shared: true do
-  it "returns the tangent of the argument" do
-    @object.send(:tan, 0.0).should == 0.0
-    @object.send(:tan, -0.0).should == -0.0
-    @object.send(:tan, 4.22).should be_close(1.86406937682395, TOLERANCE)
-    @object.send(:tan, -9.65).should be_close(-0.229109052606441, TOLERANCE)
-  end
-
-  it "returns the tangent for Complex numbers" do
-    @object.send(:tan, Complex(0, CMath::PI)).should be_close(Complex(0.0, 0.99627207622075), TOLERANCE)
-    @object.send(:tan, Complex(3, 4)).should be_close(Complex(-0.000187346204629452, 0.999355987381473), TOLERANCE)
-  end
-end
-
-describe :complex_math_tan_bang, shared: true do
-  it "returns the tangent of the argument" do
-    @object.send(:tan!, 0.0).should == 0.0
-    @object.send(:tan!, -0.0).should == -0.0
-    @object.send(:tan!, 4.22).should be_close(1.86406937682395, TOLERANCE)
-    @object.send(:tan!, -9.65).should be_close(-0.229109052606441, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:tan!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/shared/tanh.rb b/spec/ruby/library/cmath/math/shared/tanh.rb
deleted file mode 100644
index f2c9a5abb1..0000000000
--- a/spec/ruby/library/cmath/math/shared/tanh.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../fixtures/classes'
-
-describe :complex_math_tanh, shared: true do
-  it "returns the hyperbolic tangent of the argument" do
-    @object.send(:tanh, 0.0).should == 0.0
-    @object.send(:tanh, -0.0).should == -0.0
-    @object.send(:tanh, infinity_value).should == 1.0
-    @object.send(:tanh, -infinity_value).should == -1.0
-    @object.send(:tanh, 2.5).should be_close(0.98661429815143, TOLERANCE)
-    @object.send(:tanh, -4.892).should be_close(-0.999887314427707, TOLERANCE)
-  end
-
-  it "returns the hyperbolic tangent for Complex numbers" do
-    @object.send(:tanh, Complex(0, CMath::PI)).should be_close(Complex(0.0, -1.22464679914735e-16), TOLERANCE)
-    @object.send(:tanh, Complex(3, 4)).should be_close(Complex(1.00070953606723, 0.00490825806749599), TOLERANCE)
-  end
-end
-
-describe :complex_math_tanh_bang, shared: true do
-  it "returns the hyperbolic tangent of the argument" do
-    @object.send(:tanh!, 0.0).should == 0.0
-    @object.send(:tanh!, -0.0).should == -0.0
-    @object.send(:tanh!, infinity_value).should == 1.0
-    @object.send(:tanh!, -infinity_value).should == -1.0
-    @object.send(:tanh!, 2.5).should be_close(0.98661429815143, TOLERANCE)
-    @object.send(:tanh!, -4.892).should be_close(-0.999887314427707, TOLERANCE)
-  end
-
-  it "raises a TypeError when passed a Complex number" do
-    -> { @object.send(:tanh!, Complex(4, 5)) }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/cmath/math/sin_spec.rb b/spec/ruby/library/cmath/math/sin_spec.rb
deleted file mode 100644
index b7a219fbbd..0000000000
--- a/spec/ruby/library/cmath/math/sin_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/sin'
-
-  describe "Math#sin" do
-    it_behaves_like :complex_math_sin, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:sin)
-    end
-  end
-
-  describe "Math.sin" do
-    it_behaves_like :complex_math_sin, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/sinh_spec.rb b/spec/ruby/library/cmath/math/sinh_spec.rb
deleted file mode 100644
index c6e6a3baf4..0000000000
--- a/spec/ruby/library/cmath/math/sinh_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/sinh'
-
-  describe "Math#sinh" do
-    it_behaves_like :complex_math_sinh, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:sinh)
-    end
-  end
-
-  describe "Math.sinh" do
-    it_behaves_like :complex_math_sinh, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/sqrt_spec.rb b/spec/ruby/library/cmath/math/sqrt_spec.rb
deleted file mode 100644
index 421824f99c..0000000000
--- a/spec/ruby/library/cmath/math/sqrt_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/sqrt'
-
-  describe "Math#sqrt" do
-    it_behaves_like :complex_math_sqrt, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:sqrt)
-    end
-  end
-
-  describe "Math.sqrt" do
-    it_behaves_like :complex_math_sqrt, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/tan_spec.rb b/spec/ruby/library/cmath/math/tan_spec.rb
deleted file mode 100644
index e2acdd8091..0000000000
--- a/spec/ruby/library/cmath/math/tan_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/tan'
-
-  describe "Math#tan" do
-    it_behaves_like :complex_math_tan, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:tan)
-    end
-  end
-
-  describe "Math.tan" do
-    it_behaves_like :complex_math_tan, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/cmath/math/tanh_spec.rb b/spec/ruby/library/cmath/math/tanh_spec.rb
deleted file mode 100644
index 94da20cd51..0000000000
--- a/spec/ruby/library/cmath/math/tanh_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require 'complex'
-  require_relative 'shared/tanh'
-
-  describe "Math#tanh" do
-    it_behaves_like :complex_math_tanh, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:tanh)
-    end
-  end
-
-  describe "Math.tanh" do
-    it_behaves_like :complex_math_tanh, :_, CMath
-  end
-end
diff --git a/spec/ruby/library/conditionvariable/broadcast_spec.rb b/spec/ruby/library/conditionvariable/broadcast_spec.rb
deleted file mode 100644
index a31a0443bd..0000000000
--- a/spec/ruby/library/conditionvariable/broadcast_spec.rb
+++ /dev/null
@@ -1,67 +0,0 @@
-require_relative '../../spec_helper'
-require 'thread'
-
-describe "ConditionVariable#broadcast" do
-  it "returns self if nothing to broadcast to" do
-    cv = ConditionVariable.new
-    cv.broadcast.should == cv
-  end
-
-  it "returns self if something is waiting for a broadcast" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    in_synchronize = false
-
-    th = Thread.new do
-      m.synchronize do
-        in_synchronize = true
-        cv.wait(m)
-      end
-    end
-
-    # wait for m to acquire the mutex
-    Thread.pass until in_synchronize
-    # wait until th is sleeping (ie waiting)
-    Thread.pass while th.status and th.status != "sleep"
-
-    m.synchronize { cv.broadcast }.should == cv
-
-    th.join
-  end
-
-  it "releases all threads waiting in line for this resource" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    threads = []
-    r1 = []
-    r2 = []
-
-    # large number to attempt to cause race conditions
-    100.times do |i|
-      threads << Thread.new(i) do |tid|
-        m.synchronize do
-          r1 << tid
-          cv.wait(m)
-          r2 << tid
-        end
-      end
-    end
-
-    # wait for all threads to acquire the mutex the first time
-    Thread.pass until m.synchronize { r1.size == threads.size }
-    # wait until all threads are sleeping (ie waiting)
-    Thread.pass until threads.all? {|th| th.status == "sleep" }
-
-    r2.should be_empty
-    m.synchronize do
-      cv.broadcast
-    end
-
-    threads.each {|t| t.join }
-
-    # ensure that all threads that enter cv.wait are released
-    r2.sort.should == r1.sort
-    # note that order is not specified as broadcast results in a race
-    # condition on regaining the lock m
-  end
-end
diff --git a/spec/ruby/library/conditionvariable/marshal_dump_spec.rb b/spec/ruby/library/conditionvariable/marshal_dump_spec.rb
deleted file mode 100644
index f951a13e28..0000000000
--- a/spec/ruby/library/conditionvariable/marshal_dump_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-require 'thread'
-
-describe "ConditionVariable#marshal_dump" do
-  it "raises a TypeError" do
-    cv = ConditionVariable.new
-    -> { cv.marshal_dump }.should raise_error(TypeError, /can't dump/)
-  end
-end
diff --git a/spec/ruby/library/conditionvariable/signal_spec.rb b/spec/ruby/library/conditionvariable/signal_spec.rb
deleted file mode 100644
index 0dafe8527f..0000000000
--- a/spec/ruby/library/conditionvariable/signal_spec.rb
+++ /dev/null
@@ -1,69 +0,0 @@
-require_relative '../../spec_helper'
-require 'thread'
-
-describe "ConditionVariable#signal" do
-  it "returns self if nothing to signal" do
-    cv = ConditionVariable.new
-    cv.signal.should == cv
-  end
-
-  it "returns self if something is waiting for a signal" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    in_synchronize = false
-
-    th = Thread.new do
-      m.synchronize do
-        in_synchronize = true
-        cv.wait(m)
-      end
-    end
-
-    # wait for m to acquire the mutex
-    Thread.pass until in_synchronize
-    # wait until th is sleeping (ie waiting)
-    Thread.pass while th.status and th.status != "sleep"
-
-    m.synchronize { cv.signal }.should == cv
-
-    th.join
-  end
-
-  it "releases the first thread waiting in line for this resource" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    threads = []
-    r1 = []
-    r2 = []
-
-    # large number to attempt to cause race conditions
-    100.times do |i|
-      threads << Thread.new(i) do |tid|
-        m.synchronize do
-          r1 << tid
-          cv.wait(m)
-          r2 << tid
-        end
-      end
-    end
-
-    # wait for all threads to acquire the mutex the first time
-    Thread.pass until m.synchronize { r1.size == threads.size }
-    # wait until all threads are sleeping (ie waiting)
-    Thread.pass until threads.all? {|th| th.status == "sleep" }
-
-    r2.should be_empty
-    100.times do |i|
-      m.synchronize do
-        cv.signal
-      end
-      Thread.pass until r2.size == i+1
-    end
-
-    threads.each {|t| t.join }
-
-    # ensure that all the threads that went into the cv.wait are
-    # released in the same order
-    r2.should == r1
-  end
-end
diff --git a/spec/ruby/library/conditionvariable/wait_spec.rb b/spec/ruby/library/conditionvariable/wait_spec.rb
deleted file mode 100644
index f57ab4c778..0000000000
--- a/spec/ruby/library/conditionvariable/wait_spec.rb
+++ /dev/null
@@ -1,132 +0,0 @@
-require_relative '../../spec_helper'
-require 'thread'
-
-describe "ConditionVariable#wait" do
-  it "calls #sleep on the given object" do
-    o = Object.new
-    o.should_receive(:sleep).with(1234)
-
-    cv = ConditionVariable.new
-
-    cv.wait(o, 1234)
-  end
-
-  it "returns self" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    in_synchronize = false
-
-    th = Thread.new do
-      m.synchronize do
-        in_synchronize = true
-        cv.wait(m).should == cv
-      end
-    end
-
-    # wait for m to acquire the mutex
-    Thread.pass until in_synchronize
-    # wait until th is sleeping (ie waiting)
-    Thread.pass while th.status and th.status != "sleep"
-
-    m.synchronize { cv.signal }
-    th.join
-  end
-
-  it "reacquires the lock even if the thread is killed" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    in_synchronize = false
-    owned = nil
-
-    th = Thread.new do
-      m.synchronize do
-        in_synchronize = true
-        begin
-          cv.wait(m)
-        ensure
-          owned = m.owned?
-          $stderr.puts "\nThe Thread doesn't own the Mutex!" unless owned
-        end
-      end
-    end
-
-    # wait for m to acquire the mutex
-    Thread.pass until in_synchronize
-    # wait until th is sleeping (ie waiting)
-    Thread.pass while th.status and th.status != "sleep"
-
-    th.kill
-    th.join
-
-    owned.should == true
-  end
-
-  ruby_bug '#14999', ''...'2.5' do
-    it "reacquires the lock even if the thread is killed after being signaled" do
-      m = Mutex.new
-      cv = ConditionVariable.new
-      in_synchronize = false
-      owned = nil
-
-      th = Thread.new do
-        m.synchronize do
-          in_synchronize = true
-          begin
-            cv.wait(m)
-          ensure
-            owned = m.owned?
-            $stderr.puts "\nThe Thread doesn't own the Mutex!" unless owned
-          end
-        end
-      end
-
-      # wait for m to acquire the mutex
-      Thread.pass until in_synchronize
-      # wait until th is sleeping (ie waiting)
-      Thread.pass while th.status and th.status != "sleep"
-
-      m.synchronize {
-        cv.signal
-        # Wait that the thread is blocked on acquiring the Mutex
-        sleep 0.001
-        # Kill the thread, yet the thread should first acquire the Mutex before going on
-        th.kill
-      }
-
-      th.join
-      owned.should == true
-    end
-  end
-
-  it "supports multiple Threads waiting on the same ConditionVariable and Mutex" do
-    m = Mutex.new
-    cv = ConditionVariable.new
-    n_threads = 4
-    events = []
-
-    threads = n_threads.times.map {
-      Thread.new {
-        m.synchronize {
-          events << :t_in_synchronize
-          cv.wait(m)
-        }
-      }
-    }
-
-    Thread.pass until m.synchronize { events.size } == n_threads
-    Thread.pass while threads.any? { |th| th.status and th.status != "sleep" }
-    m.synchronize do
-      threads.each { |t|
-        # Cause interactions with the waiting threads.
-        # On TruffleRuby, this causes a safepoint which has interesting
-        # interactions with the ConditionVariable.
-        bt = t.backtrace
-        bt.should be_kind_of(Array)
-        bt.size.should >= 2
-      }
-    end
-
-    cv.broadcast
-    threads.each(&:join)
-  end
-end
diff --git a/spec/ruby/library/coverage/fixtures/code_with_begin.rb b/spec/ruby/library/coverage/fixtures/code_with_begin.rb
new file mode 100644
index 0000000000..9a6384e337
--- /dev/null
+++ b/spec/ruby/library/coverage/fixtures/code_with_begin.rb
@@ -0,0 +1,3 @@
+begin
+  'coverage with begin'
+end
diff --git a/spec/ruby/library/coverage/fixtures/eval_code.rb b/spec/ruby/library/coverage/fixtures/eval_code.rb
new file mode 100644
index 0000000000..8ab82218f3
--- /dev/null
+++ b/spec/ruby/library/coverage/fixtures/eval_code.rb
@@ -0,0 +1,11 @@
+5 + 5
+
+module CoverageSpecs
+
+  class_eval <<-RUBY, __FILE__, __LINE__ + 1
+    attr_reader :ok
+  RUBY
+
+end
+
+4 + 4
diff --git a/spec/ruby/library/coverage/result_spec.rb b/spec/ruby/library/coverage/result_spec.rb
index ebfa5538b4..2e7d598bb8 100644
--- a/spec/ruby/library/coverage/result_spec.rb
+++ b/spec/ruby/library/coverage/result_spec.rb
@@ -5,11 +5,21 @@ describe 'Coverage.result' do
   before :all do
     @class_file = fixture __FILE__, 'some_class.rb'
     @config_file = fixture __FILE__, 'start_coverage.rb'
+    @eval_code_file = fixture __FILE__, 'eval_code.rb'
+    @with_begin_file = fixture __FILE__, 'code_with_begin.rb'
+  end
+
+  before :each do
+    Coverage.running?.should == false
   end
 
   after :each do
     $LOADED_FEATURES.delete(@class_file)
     $LOADED_FEATURES.delete(@config_file)
+    $LOADED_FEATURES.delete(@eval_code_file)
+    $LOADED_FEATURES.delete(@with_begin_file)
+
+    Coverage.result if Coverage.running?
   end
 
   it 'gives the covered files as a hash with arrays of count or nil' do
@@ -24,6 +34,39 @@ describe 'Coverage.result' do
     }
   end
 
+  it 'returns results for each mode separately when enabled :all modes' do
+    Coverage.start(:all)
+    require @class_file.chomp('.rb')
+    result = Coverage.result
+
+    result.should == {
+      @class_file => {
+        lines: [
+          nil, nil, 1, nil, nil, 1, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+        ],
+        branches: {},
+        methods: {
+          [SomeClass, :some_method, 6, 2, 11, 5] => 0
+        }
+      }
+    }
+  end
+
+  it 'returns results for each mode separately when enabled any mode explicitly' do
+    Coverage.start(lines: true)
+    require @class_file.chomp('.rb')
+    result = Coverage.result
+
+    result.should == {
+      @class_file =>
+        {
+          lines: [
+            nil, nil, 1, nil, nil, 1, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+          ]
+        }
+    }
+  end
+
   it 'no requires/loads should give empty hash' do
     Coverage.start
     result = Coverage.result
@@ -35,8 +78,9 @@ describe 'Coverage.result' do
     Coverage.start
     require @class_file.chomp('.rb')
     Coverage.result
-    -> { Coverage.result }
-      .should raise_error(RuntimeError, 'coverage measurement is not enabled')
+    -> {
+      Coverage.result
+    }.should.raise(RuntimeError, 'coverage measurement is not enabled')
   end
 
   it 'second run should give same result' do
@@ -62,16 +106,238 @@ describe 'Coverage.result' do
     result.should == {}
   end
 
-  it 'second Coverage.start does nothing' do
-    Coverage.start
+  it 'does not include the file starting coverage since it is not tracked' do
     require @config_file.chomp('.rb')
+    Coverage.result.should_not.include?(@config_file)
+  end
+
+  it 'returns the correct results when eval coverage is enabled' do
+    Coverage.supported?(:eval).should == true
+
+    Coverage.start(lines: true, eval: true)
+    require @eval_code_file.chomp('.rb')
     result = Coverage.result
 
-    result.should == { @config_file => [1, 1, 1] }
+    result.should == {
+      @eval_code_file => {
+        lines: [1, nil, 1, nil, 1, 1, nil, nil, nil, nil, 1]
+      }
+    }
   end
 
-  it 'does not include the file starting coverage since it is not tracked' do
-    require @config_file.chomp('.rb')
-    Coverage.result.should_not include(@config_file)
+  it 'returns the correct results when eval coverage is disabled' do
+    Coverage.supported?(:eval).should == true
+
+    Coverage.start(lines: true, eval: false)
+    require @eval_code_file.chomp('.rb')
+    result = Coverage.result
+
+    result.should == {
+      @eval_code_file => {
+        lines: [1, nil, 1, nil, 1, nil, nil, nil, nil, nil, 1]
+      }
+    }
+  end
+
+  it "disables coverage measurement when stop option is not specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result
+    Coverage.running?.should == false
+  end
+
+  it "disables coverage measurement when stop: true option is specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    -> {
+      Coverage.result(stop: true)
+    }.should complain(/warning: stop implies clear/)
+
+    Coverage.running?.should == false
+  end
+
+  it "does not disable coverage measurement when stop: false option is specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: false)
+    Coverage.running?.should == true
+  end
+
+  it "does not disable coverage measurement when stop option is not specified but clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(clear: true)
+    Coverage.running?.should == true
+  end
+
+  it "does not disable coverage measurement when stop option is not specified but clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(clear: false)
+    Coverage.running?.should == true
+  end
+
+  it "disables coverage measurement when stop: true and clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: true, clear: true)
+    Coverage.running?.should == false
+  end
+
+  it "disables coverage measurement when stop: true and clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    -> {
+      Coverage.result(stop: true, clear: false)
+    }.should complain(/warning: stop implies clear/)
+
+    Coverage.running?.should == false
+  end
+
+  it "does not disable coverage measurement when stop: false and clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: false, clear: true)
+    Coverage.running?.should == true
+  end
+
+  it "does not disable coverage measurement when stop: false and clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: false, clear: false)
+    Coverage.running?.should == true
+  end
+
+  it "resets counters (remove them) when stop: true specified but clear option is not specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    -> {
+      Coverage.result(stop: true) # clears counters
+    }.should complain(/warning: stop implies clear/)
+
+    Coverage.start
+    Coverage.peek_result.should == {}
+  end
+
+  it "resets counters (remove them) when stop: true and clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: true, clear: true) # clears counters
+
+    Coverage.start
+    Coverage.peek_result.should == {}
+  end
+
+  it "resets counters (remove them) when stop: true and clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    -> {
+      Coverage.result(stop: true, clear: false) # clears counters
+    }.should complain(/warning: stop implies clear/)
+
+    Coverage.start
+    Coverage.peek_result.should == {}
+  end
+
+  it "resets counters (remove them) when both stop and clear options are not specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result # clears counters
+
+    Coverage.start
+    Coverage.peek_result.should == {}
+  end
+
+  it "clears counters (sets 0 values) when stop is not specified but clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(clear: true) # clears counters
+
+    Coverage.peek_result.should == {
+      @class_file => [
+        nil, nil, 0, nil, nil, 0, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+      ]
+    }
+  end
+
+  it "does not clear counters when stop is not specified but clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    result = Coverage.result(clear: false) # doesn't clear counters
+    result.should == {
+      @class_file => [
+        nil, nil, 1, nil, nil, 1, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+      ]
+    }
+
+    Coverage.peek_result.should == result
+  end
+
+  it "does not clear counters when stop: false and clear is not specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    result = Coverage.result(stop: false) # doesn't clear counters
+    result.should == {
+      @class_file => [
+        nil, nil, 1, nil, nil, 1, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+      ]
+    }
+
+    Coverage.peek_result.should == result
+  end
+
+  it "clears counters (sets 0 values) when stop: false and clear: true specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    Coverage.result(stop: false, clear: true) # clears counters
+
+    Coverage.peek_result.should == {
+      @class_file => [
+        nil, nil, 0, nil, nil, 0, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+      ]
+    }
+  end
+
+  it "does not clear counters when stop: false and clear: false specified" do
+    Coverage.start
+    require @class_file.chomp('.rb')
+
+    result = Coverage.result(stop: false, clear: false) # doesn't clear counters
+    result.should == {
+      @class_file => [
+        nil, nil, 1, nil, nil, 1, nil, nil, 0, nil, nil, nil, nil, nil, nil, nil
+      ]
+    }
+
+    Coverage.peek_result.should == result
+  end
+
+  it 'covers 100% lines with begin' do
+    Coverage.start
+    require @with_begin_file.chomp('.rb')
+    result = Coverage.result
+
+    result.should == {
+      @with_begin_file => [
+        nil, 1, nil
+      ]
+    }
   end
 end
diff --git a/spec/ruby/library/coverage/running_spec.rb b/spec/ruby/library/coverage/running_spec.rb
new file mode 100644
index 0000000000..e9cc7ada5a
--- /dev/null
+++ b/spec/ruby/library/coverage/running_spec.rb
@@ -0,0 +1,20 @@
+require_relative '../../spec_helper'
+require 'coverage'
+
+describe 'Coverage.running?' do
+  it "returns false if coverage is not started" do
+    Coverage.running?.should == false
+  end
+
+  it "returns true if coverage is started" do
+    Coverage.start
+    Coverage.running?.should == true
+    Coverage.result
+  end
+
+  it "returns false if coverage was started and stopped" do
+    Coverage.start
+    Coverage.result
+    Coverage.running?.should == false
+  end
+end
diff --git a/spec/ruby/library/coverage/start_spec.rb b/spec/ruby/library/coverage/start_spec.rb
index ddfad8b47c..11777347a2 100644
--- a/spec/ruby/library/coverage/start_spec.rb
+++ b/spec/ruby/library/coverage/start_spec.rb
@@ -2,5 +2,86 @@ require_relative '../../spec_helper'
 require 'coverage'
 
 describe 'Coverage.start' do
-  it 'needs to be reviewed for spec completeness'
+  before :each do
+    Coverage.should_not.running?
+  end
+
+  after :each do
+    Coverage.result(stop: true, clear: true) if Coverage.running?
+  end
+
+  it "enables the coverage measurement" do
+    Coverage.start
+    Coverage.should.running?
+  end
+
+  it "returns nil" do
+    Coverage.start.should == nil
+  end
+
+  it 'raises error when repeated Coverage.start call happens' do
+    Coverage.start
+
+    -> {
+      Coverage.start
+    }.should.raise(RuntimeError, 'coverage measurement is already setup')
+  end
+
+  it "accepts :all optional argument" do
+    Coverage.start(:all)
+    Coverage.should.running?
+  end
+
+  it "accepts lines: optional keyword argument" do
+    Coverage.start(lines: true)
+    Coverage.should.running?
+  end
+
+  it "accepts branches: optional keyword argument" do
+    Coverage.start(branches: true)
+    Coverage.should.running?
+  end
+
+  it "accepts methods: optional keyword argument" do
+    Coverage.start(methods: true)
+    Coverage.should.running?
+  end
+
+  it "accepts eval: optional keyword argument" do
+    Coverage.start(eval: true)
+    Coverage.should.running?
+  end
+
+  it "accepts oneshot_lines: optional keyword argument" do
+    Coverage.start(oneshot_lines: true)
+    Coverage.should.running?
+  end
+
+  it "ignores unknown keyword arguments" do
+    Coverage.start(foo: true)
+    Coverage.should.running?
+  end
+
+  it "expects a Hash if not passed :all" do
+    -> {
+      Coverage.start(42)
+    }.should.raise(TypeError, "no implicit conversion of Integer into Hash")
+  end
+
+  it "does not accept both lines: and oneshot_lines: keyword arguments" do
+    -> {
+      Coverage.start(lines: true, oneshot_lines: true)
+    }.should.raise(RuntimeError, "cannot enable lines and oneshot_lines simultaneously")
+  end
+
+  it "enables the coverage measurement if passed options with `false` value" do
+    Coverage.start(lines: false, branches: false, methods: false, eval: false, oneshot_lines: false)
+    Coverage.should.running?
+  end
+
+  it "measures coverage within eval" do
+    Coverage.start(lines: true, eval: true)
+    eval("Object.new\n"*3, binding, "test.rb", 1)
+    Coverage.result["test.rb"].should == {lines: [1, 1, 1]}
+  end
 end
diff --git a/spec/ruby/library/coverage/supported_spec.rb b/spec/ruby/library/coverage/supported_spec.rb
new file mode 100644
index 0000000000..fcf8a76d79
--- /dev/null
+++ b/spec/ruby/library/coverage/supported_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+require 'coverage'
+
+describe "Coverage.supported?" do
+  it "returns true or false if coverage measurement is supported for the given mode" do
+    [true, false].should.include?(Coverage.supported?(:lines))
+    [true, false].should.include?(Coverage.supported?(:branches))
+    [true, false].should.include?(Coverage.supported?(:methods))
+    [true, false].should.include?(Coverage.supported?(:eval))
+  end
+
+  it "returns false for not existing modes" do
+    Coverage.supported?(:foo).should == false
+    Coverage.supported?(:bar).should == false
+  end
+
+  it "raise TypeError if argument is not Symbol" do
+    -> {
+      Coverage.supported?("lines")
+    }.should.raise(TypeError, "wrong argument type String (expected Symbol)")
+
+    -> {
+      Coverage.supported?([])
+    }.should.raise(TypeError, "wrong argument type Array (expected Symbol)")
+
+    -> {
+      Coverage.supported?(1)
+    }.should.raise(TypeError, "wrong argument type Integer (expected Symbol)")
+  end
+end
diff --git a/spec/ruby/library/csv/generate_spec.rb b/spec/ruby/library/csv/generate_spec.rb
index 0a1e3d9604..62e19aa6e4 100644
--- a/spec/ruby/library/csv/generate_spec.rb
+++ b/spec/ruby/library/csv/generate_spec.rb
@@ -21,12 +21,12 @@ describe "CSV.generate" do
   end
 
   it "appends and returns the argument itself" do
-    str = ""
+    str = +""
     csv_str = CSV.generate(str) do |csv|
       csv.add_row [1, 2, 3]
       csv << [4, 5, 6]
     end
-    csv_str.should equal str
+    csv_str.should.equal? str
     str.should == "1,2,3\n4,5,6\n"
   end
 end
diff --git a/spec/ruby/library/csv/liberal_parsing_spec.rb b/spec/ruby/library/csv/liberal_parsing_spec.rb
index 2929d6e2aa..9878658027 100644
--- a/spec/ruby/library/csv/liberal_parsing_spec.rb
+++ b/spec/ruby/library/csv/liberal_parsing_spec.rb
@@ -4,16 +4,16 @@ require 'csv'
 describe "CSV#liberal_parsing?" do
   it "returns true if illegal input is handled" do
     csv = CSV.new("", liberal_parsing: true)
-    csv.liberal_parsing?.should == true
+    csv.should.liberal_parsing?
   end
 
   it "returns false if illegal input is not handled" do
     csv = CSV.new("", liberal_parsing: false)
-    csv.liberal_parsing?.should == false
+    csv.should_not.liberal_parsing?
   end
 
   it "returns false by default" do
     csv = CSV.new("")
-    csv.liberal_parsing?.should == false
+    csv.should_not.liberal_parsing?
   end
 end
diff --git a/spec/ruby/library/csv/parse_spec.rb b/spec/ruby/library/csv/parse_spec.rb
index ef5d4ea3ca..7000f03cda 100644
--- a/spec/ruby/library/csv/parse_spec.rb
+++ b/spec/ruby/library/csv/parse_spec.rb
@@ -5,7 +5,7 @@ describe "CSV.parse" do
 
   it "parses '' into []" do
     result = CSV.parse ''
-    result.should be_kind_of(Array)
+    result.should.is_a?(Array)
     result.should == []
   end
 
@@ -82,7 +82,7 @@ describe "CSV.parse" do
   it "raises CSV::MalformedCSVError exception if input is illegal" do
     -> {
       CSV.parse('"quoted" field')
-    }.should raise_error(CSV::MalformedCSVError)
+    }.should.raise(CSV::MalformedCSVError)
   end
 
   it "handles illegal input with the liberal_parsing option" do
diff --git a/spec/ruby/library/csv/readlines_spec.rb b/spec/ruby/library/csv/readlines_spec.rb
index 14dea34381..624f906489 100644
--- a/spec/ruby/library/csv/readlines_spec.rb
+++ b/spec/ruby/library/csv/readlines_spec.rb
@@ -23,7 +23,7 @@ describe "CSV#readlines" do
 
   it "raises CSV::MalformedCSVError exception if input is illegal" do
     csv = CSV.new('"quoted" field')
-    -> { csv.readlines }.should raise_error(CSV::MalformedCSVError)
+    -> { csv.readlines }.should.raise(CSV::MalformedCSVError)
   end
 
   it "handles illegal input with the liberal_parsing option" do
diff --git a/spec/ruby/library/date/accessor_spec.rb b/spec/ruby/library/date/accessor_spec.rb
index 68a2d9f3de..74ed0e9c21 100644
--- a/spec/ruby/library/date/accessor_spec.rb
+++ b/spec/ruby/library/date/accessor_spec.rb
@@ -38,7 +38,7 @@ describe "Date#year" do
 end
 
 describe "Date#yday" do
-  it "determines the year" do
+  it "determines the day of the year" do
     Date.civil(2007,  1, 17).yday.should == 17
     Date.civil(2008, 10, 28).yday.should == 302
   end
diff --git a/spec/ruby/library/date/add_month_spec.rb b/spec/ruby/library/date/add_month_spec.rb
index 40833f6487..ab802ea97a 100644
--- a/spec/ruby/library/date/add_month_spec.rb
+++ b/spec/ruby/library/date/add_month_spec.rb
@@ -21,18 +21,18 @@ describe "Date#>>" do
   end
 
   it "raise a TypeError when passed a Symbol" do
-    -> { Date.civil(2007,2,27) >> :hello }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) >> :hello }.should.raise(TypeError)
   end
 
   it "raise a TypeError when passed a String" do
-    -> { Date.civil(2007,2,27) >> "hello" }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) >> "hello" }.should.raise(TypeError)
   end
 
   it "raise a TypeError when passed a Date" do
-    -> { Date.civil(2007,2,27) >> Date.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) >> Date.new }.should.raise(TypeError)
   end
 
   it "raise a TypeError when passed an Object" do
-    -> { Date.civil(2007,2,27) >> Object.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) >> Object.new }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/date/add_spec.rb b/spec/ruby/library/date/add_spec.rb
index 2b9cc62023..5e368decdc 100644
--- a/spec/ruby/library/date/add_spec.rb
+++ b/spec/ruby/library/date/add_spec.rb
@@ -13,18 +13,18 @@ describe "Date#+" do
   end
 
   it "raises a TypeError when passed a Symbol" do
-    -> { Date.civil(2007,2,27) + :hello }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) + :hello }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a String" do
-    -> { Date.civil(2007,2,27) + "hello" }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) + "hello" }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed a Date" do
-    -> { Date.civil(2007,2,27) + Date.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) + Date.new }.should.raise(TypeError)
   end
 
   it "raises a TypeError when passed an Object" do
-    -> { Date.civil(2007,2,27) + Object.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) + Object.new }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/date/civil_spec.rb b/spec/ruby/library/date/civil_spec.rb
index f3537c2f84..1c780fce56 100644
--- a/spec/ruby/library/date/civil_spec.rb
+++ b/spec/ruby/library/date/civil_spec.rb
@@ -2,11 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'shared/civil'
 require 'date'
 
-describe "Date#civil" do
-  it_behaves_like :date_civil, :civil
-end
-
-
 describe "Date.civil" do
-  it "needs to be reviewed for spec completeness"
+  it_behaves_like :date_civil, :civil
 end
diff --git a/spec/ruby/library/date/constants_spec.rb b/spec/ruby/library/date/constants_spec.rb
index fc1dba4999..3494b0c296 100644
--- a/spec/ruby/library/date/constants_spec.rb
+++ b/spec/ruby/library/date/constants_spec.rb
@@ -36,11 +36,11 @@ describe "Date constants" do
     [Date::MONTHNAMES, Date::DAYNAMES, Date::ABBR_MONTHNAMES, Date::ABBR_DAYNAMES].each do |ary|
       -> {
         ary << "Unknown"
-      }.should raise_error(frozen_error_class, /frozen/)
+      }.should.raise(FrozenError, /frozen/)
       ary.compact.each do |name|
         -> {
           name << "modified"
-        }.should raise_error(frozen_error_class, /frozen/)
+        }.should.raise(FrozenError, /frozen/)
       end
     end
   end
diff --git a/spec/ruby/library/date/deconstruct_keys_spec.rb b/spec/ruby/library/date/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..1fa1e70250
--- /dev/null
+++ b/spec/ruby/library/date/deconstruct_keys_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require 'date'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
+
+describe "Date#deconstruct_keys" do
+  it "returns whole hash for nil as an argument" do
+    d = Date.new(2022, 10, 5)
+    d.deconstruct_keys(nil).should == { year: 2022, month: 10, day: 5, yday: 278, wday: 3 }
+  end
+
+  it "returns only specified keys" do
+    d = Date.new(2022, 10, 5)
+    d.deconstruct_keys([:year, :month]).should == { year: 2022, month: 10 }
+  end
+
+  it "requires one argument" do
+    -> {
+      Date.new(2022, 10, 5).deconstruct_keys
+    }.should.raise(ArgumentError)
+  end
+
+  it "it raises error when argument is neither nil nor array" do
+    d = Date.new(2022, 10, 5)
+
+    -> { d.deconstruct_keys(1) }.should.raise(TypeError, "wrong argument type Integer (expected Array or nil)")
+    -> { d.deconstruct_keys("asd") }.should.raise(TypeError, "wrong argument type String (expected Array or nil)")
+    -> { d.deconstruct_keys(:x) }.should.raise(TypeError, "wrong argument type Symbol (expected Array or nil)")
+    -> { d.deconstruct_keys({}) }.should.raise(TypeError, "wrong argument type Hash (expected Array or nil)")
+  end
+
+  it "returns {} when passed []" do
+    Date.new(2022, 10, 5).deconstruct_keys([]).should == {}
+  end
+
+  it "ignores non-Symbol keys" do
+    Date.new(2022, 10, 5).deconstruct_keys(['year', []]).should == {}
+  end
+
+  it "ignores not existing Symbol keys" do
+    Date.new(2022, 10, 5).deconstruct_keys([:year, :a]).should == { year: 2022 }
+  end
+end
diff --git a/spec/ruby/library/date/eql_spec.rb b/spec/ruby/library/date/eql_spec.rb
index a1819cae3a..79fabc47f4 100644
--- a/spec/ruby/library/date/eql_spec.rb
+++ b/spec/ruby/library/date/eql_spec.rb
@@ -3,10 +3,10 @@ require 'date'
 
 describe "Date#eql?" do
   it "returns true if self is equal to another date" do
-    Date.civil(2007, 10, 11).eql?(Date.civil(2007, 10, 11)).should be_true
+    Date.civil(2007, 10, 11).eql?(Date.civil(2007, 10, 11)).should == true
   end
 
   it "returns false if self is not equal to another date" do
-    Date.civil(2007, 10, 11).eql?(Date.civil(2007, 10, 12)).should be_false
+    Date.civil(2007, 10, 11).eql?(Date.civil(2007, 10, 12)).should == false
   end
 end
diff --git a/spec/ruby/library/date/friday_spec.rb b/spec/ruby/library/date/friday_spec.rb
index 3dc040fabe..62f050346e 100644
--- a/spec/ruby/library/date/friday_spec.rb
+++ b/spec/ruby/library/date/friday_spec.rb
@@ -3,10 +3,10 @@ require 'date'
 
 describe "Date#friday?" do
   it "should be friday" do
-    Date.new(2000, 1, 7).friday?.should be_true
+    Date.new(2000, 1, 7).friday?.should == true
   end
 
   it "should not be friday" do
-    Date.new(2000, 1, 8).friday?.should be_false
+    Date.new(2000, 1, 8).friday?.should == false
   end
 end
diff --git a/spec/ruby/library/date/gregorian_leap_spec.rb b/spec/ruby/library/date/gregorian_leap_spec.rb
index c3d25cf90f..c27890faf4 100644
--- a/spec/ruby/library/date/gregorian_leap_spec.rb
+++ b/spec/ruby/library/date/gregorian_leap_spec.rb
@@ -3,13 +3,13 @@ require 'date'
 
 describe "Date#gregorian_leap?" do
   it "returns true if a year is a leap year in the Gregorian calendar" do
-    Date.gregorian_leap?(2000).should be_true
-    Date.gregorian_leap?(2004).should be_true
+    Date.gregorian_leap?(2000).should == true
+    Date.gregorian_leap?(2004).should == true
   end
 
   it "returns false if a year is not a leap year in the Gregorian calendar" do
-    Date.gregorian_leap?(1900).should be_false
-    Date.gregorian_leap?(1999).should be_false
-    Date.gregorian_leap?(2002).should be_false
+    Date.gregorian_leap?(1900).should == false
+    Date.gregorian_leap?(1999).should == false
+    Date.gregorian_leap?(2002).should == false
   end
 end
diff --git a/spec/ruby/library/date/gregorian_spec.rb b/spec/ruby/library/date/gregorian_spec.rb
index 8b7033fe75..bbda13af08 100644
--- a/spec/ruby/library/date/gregorian_spec.rb
+++ b/spec/ruby/library/date/gregorian_spec.rb
@@ -4,13 +4,13 @@ require 'date'
 describe "Date#gregorian?" do
 
   it "marks a day before the calendar reform as Julian" do
-    Date.civil(1007, 2, 27).gregorian?.should be_false
-    Date.civil(1907, 2, 27, Date.civil(1930, 1, 1).jd).gregorian?.should be_false
+    Date.civil(1007, 2, 27).gregorian?.should == false
+    Date.civil(1907, 2, 27, Date.civil(1930, 1, 1).jd).gregorian?.should == false
   end
 
   it "marks a day after the calendar reform as Julian" do
-    Date.civil(2007, 2, 27).gregorian?.should == true
-    Date.civil(1607, 2, 27, Date.civil(1582, 1, 1).jd).gregorian?.should be_true
+    Date.civil(2007, 2, 27).should.gregorian?
+    Date.civil(1607, 2, 27, Date.civil(1582, 1, 1).jd).gregorian?.should == true
   end
 
 end
diff --git a/spec/ruby/library/date/infinity_spec.rb b/spec/ruby/library/date/infinity_spec.rb
index 81d67ae249..721fd76066 100644
--- a/spec/ruby/library/date/infinity_spec.rb
+++ b/spec/ruby/library/date/infinity_spec.rb
@@ -5,16 +5,16 @@ describe "Date::Infinity" do
 
   it "should be able to check whether Infinity is zero" do
     i = Date::Infinity.new
-    i.zero?.should == false
+    i.should_not.zero?
   end
 
   it "should be able to check whether Infinity is finite" do
     i1 = Date::Infinity.new
-    i1.finite?.should == false
+    i1.should_not.finite?
     i2 = Date::Infinity.new(-1)
-    i2.finite?.should == false
+    i2.should_not.finite?
     i3 = Date::Infinity.new(0)
-    i3.finite?.should == false
+    i3.should_not.finite?
   end
 
   it "should be able to check whether Infinity is infinite" do
@@ -28,11 +28,11 @@ describe "Date::Infinity" do
 
   it "should be able to check whether Infinity is not a number" do
     i1 = Date::Infinity.new
-    i1.nan?.should == false
+    i1.should_not.nan?
     i2 = Date::Infinity.new(-1)
-    i2.nan?.should == false
+    i2.should_not.nan?
     i3 = Date::Infinity.new(0)
-    i3.nan?.should == true
+    i3.should.nan?
   end
 
   it "should be able to compare Infinity objects" do
diff --git a/spec/ruby/library/date/iso8601_spec.rb b/spec/ruby/library/date/iso8601_spec.rb
index 21b0a4cedd..26815bd76c 100644
--- a/spec/ruby/library/date/iso8601_spec.rb
+++ b/spec/ruby/library/date/iso8601_spec.rb
@@ -17,21 +17,40 @@ describe "Date.iso8601" do
     d.should == Date.civil(-4712, 1, 1)
   end
 
-  it "parses a Symbol into a Date object" do
-    d = Date.iso8601(:'2015-10-15')
-    d.should == Date.civil(2015, 10, 15)
-  end
-
   it "parses a StringSubclass into a Date object" do
     d = Date.iso8601(Class.new(String).new("-4712-01-01"))
     d.should == Date.civil(-4712, 1, 1)
   end
 
-  it "raises an ArgumentError when passed a Symbol without a valid Date" do
-    -> { Date.iso8601(:test) }.should raise_error(ArgumentError)
+  it "raises a Date::Error if the argument is a invalid Date" do
+    -> {
+      Date.iso8601('invalid')
+    }.should.raise(Date::Error, "invalid date")
+  end
+
+  it "raises a Date::Error when passed a nil" do
+    -> {
+      Date.iso8601(nil)
+    }.should.raise(Date::Error, "invalid date")
+  end
+
+  it "raises a TypeError when passed an Object" do
+    -> { Date.iso8601(Object.new) }.should.raise(TypeError)
+  end
+end
+
+describe "Date._iso8601" do
+  it "returns an empty hash if the argument is a invalid Date" do
+    h = Date._iso8601('invalid')
+    h.should == {}
+  end
+
+  it "returns an empty hash if the argument is nil" do
+    h = Date._iso8601(nil)
+    h.should == {}
   end
 
   it "raises a TypeError when passed an Object" do
-    -> { Date.iso8601(Object.new) }.should raise_error(TypeError)
+    -> { Date._iso8601(Object.new) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/date/julian_leap_spec.rb b/spec/ruby/library/date/julian_leap_spec.rb
index 2ef2d65d81..42231e012f 100644
--- a/spec/ruby/library/date/julian_leap_spec.rb
+++ b/spec/ruby/library/date/julian_leap_spec.rb
@@ -3,13 +3,13 @@ require 'date'
 
 describe "Date.julian_leap?" do
   it "determines whether a year is a leap year in the Julian calendar" do
-    Date.julian_leap?(1900).should be_true
-    Date.julian_leap?(2000).should be_true
-    Date.julian_leap?(2004).should be_true
+    Date.julian_leap?(1900).should == true
+    Date.julian_leap?(2000).should == true
+    Date.julian_leap?(2004).should == true
   end
 
   it "determines whether a year is not a leap year in the Julian calendar" do
-    Date.julian_leap?(1999).should be_false
-    Date.julian_leap?(2002).should be_false
+    Date.julian_leap?(1999).should == false
+    Date.julian_leap?(2002).should == false
   end
 end
diff --git a/spec/ruby/library/date/julian_spec.rb b/spec/ruby/library/date/julian_spec.rb
index 637a4739e5..9f8a670899 100644
--- a/spec/ruby/library/date/julian_spec.rb
+++ b/spec/ruby/library/date/julian_spec.rb
@@ -4,13 +4,13 @@ require_relative '../../spec_helper'
 describe "Date#julian?" do
 
   it "marks a day before the calendar reform as Julian" do
-    Date.civil(1007, 2, 27).julian?.should == true
-    Date.civil(1907, 2, 27, Date.civil(1930, 1, 1).jd).julian?.should be_true
+    Date.civil(1007, 2, 27).should.julian?
+    Date.civil(1907, 2, 27, Date.civil(1930, 1, 1).jd).julian?.should == true
   end
 
   it "marks a day after the calendar reform as Julian" do
-    Date.civil(2007, 2, 27).julian?.should == false
-    Date.civil(1607, 2, 27, Date.civil(1582, 1, 1).jd).julian?.should be_false
+    Date.civil(2007, 2, 27).should_not.julian?
+    Date.civil(1607, 2, 27, Date.civil(1582, 1, 1).jd).julian?.should == false
   end
 
 end
diff --git a/spec/ruby/library/date/minus_month_spec.rb b/spec/ruby/library/date/minus_month_spec.rb
index 470c4d8a76..d56e19dc31 100644
--- a/spec/ruby/library/date/minus_month_spec.rb
+++ b/spec/ruby/library/date/minus_month_spec.rb
@@ -14,10 +14,10 @@ describe "Date#<<" do
   end
 
   it "raises an error on non numeric parameters" do
-    -> { Date.civil(2007,2,27) << :hello }.should raise_error(TypeError)
-    -> { Date.civil(2007,2,27) << "hello" }.should raise_error(TypeError)
-    -> { Date.civil(2007,2,27) << Date.new }.should raise_error(TypeError)
-    -> { Date.civil(2007,2,27) << Object.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) << :hello }.should.raise(TypeError)
+    -> { Date.civil(2007,2,27) << "hello" }.should.raise(TypeError)
+    -> { Date.civil(2007,2,27) << Date.new }.should.raise(TypeError)
+    -> { Date.civil(2007,2,27) << Object.new }.should.raise(TypeError)
   end
 
 end
diff --git a/spec/ruby/library/date/minus_spec.rb b/spec/ruby/library/date/minus_spec.rb
index 5a2a29e04a..c2a08fa5b0 100644
--- a/spec/ruby/library/date/minus_spec.rb
+++ b/spec/ruby/library/date/minus_spec.rb
@@ -22,9 +22,9 @@ describe "Date#-" do
   end
 
   it "raises an error for non Numeric arguments" do
-    -> { Date.civil(2007,2,27) - :hello }.should raise_error(TypeError)
-    -> { Date.civil(2007,2,27) - "hello" }.should raise_error(TypeError)
-    -> { Date.civil(2007,2,27) - Object.new }.should raise_error(TypeError)
+    -> { Date.civil(2007,2,27) - :hello }.should.raise(TypeError)
+    -> { Date.civil(2007,2,27) - "hello" }.should.raise(TypeError)
+    -> { Date.civil(2007,2,27) - Object.new }.should.raise(TypeError)
   end
 
 end
diff --git a/spec/ruby/library/date/mon_spec.rb b/spec/ruby/library/date/mon_spec.rb
index 724e7d6564..616d72cf88 100644
--- a/spec/ruby/library/date/mon_spec.rb
+++ b/spec/ruby/library/date/mon_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
+require_relative 'shared/month'
 require 'date'
 
 describe "Date#mon" do
-  it "needs to be reviewed for spec completeness"
+  it_behaves_like :date_month, :mon
 end
diff --git a/spec/ruby/library/date/monday_spec.rb b/spec/ruby/library/date/monday_spec.rb
index 14a117b73c..61d728f3c5 100644
--- a/spec/ruby/library/date/monday_spec.rb
+++ b/spec/ruby/library/date/monday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#monday?" do
   it "should be monday" do
-    Date.new(2000, 1, 3).monday?.should be_true
+    Date.new(2000, 1, 3).monday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/month_spec.rb b/spec/ruby/library/date/month_spec.rb
index e040f9a94c..f493ec8119 100644
--- a/spec/ruby/library/date/month_spec.rb
+++ b/spec/ruby/library/date/month_spec.rb
@@ -1,9 +1,7 @@
 require_relative '../../spec_helper'
+require_relative 'shared/month'
 require 'date'
 
 describe "Date#month" do
-  it "returns the month" do
-    m = Date.new(2000, 7, 1).month
-    m.should == 7
-  end
+  it_behaves_like :date_month, :month
 end
diff --git a/spec/ruby/library/date/new_spec.rb b/spec/ruby/library/date/new_spec.rb
index 18120118c0..cb64cabce6 100644
--- a/spec/ruby/library/date/new_spec.rb
+++ b/spec/ruby/library/date/new_spec.rb
@@ -1,7 +1,6 @@
 require 'date'
 require_relative '../../spec_helper'
 require_relative 'shared/civil'
-require_relative 'shared/new_bang'
 
 describe "Date.new" do
   it_behaves_like :date_civil, :new
diff --git a/spec/ruby/library/date/parse_spec.rb b/spec/ruby/library/date/parse_spec.rb
index 379847a6fd..4d655f516e 100644
--- a/spec/ruby/library/date/parse_spec.rb
+++ b/spec/ruby/library/date/parse_spec.rb
@@ -23,7 +23,7 @@ describe "Date#parse" do
 
   # Specs using numbers
   it "throws an argument error for a single digit" do
-    ->{ Date.parse("1") }.should raise_error(ArgumentError)
+    ->{ Date.parse("1") }.should.raise(ArgumentError)
   end
 
   it "parses DD as month day number" do
@@ -66,8 +66,25 @@ describe "Date#parse" do
   end
 
   it "raises a TypeError trying to parse non-String-like object" do
-    -> { Date.parse(1) }.should raise_error(TypeError)
-    -> { Date.parse(:invalid) }.should raise_error(TypeError)
+    -> { Date.parse(1) }.should.raise(TypeError)
+    -> { Date.parse([]) }.should.raise(TypeError)
+  end
+
+  it "coerces using to_str" do
+    c = Class.new do
+      attr_accessor :string
+      def to_str
+        @string
+      end
+    end
+    o = c.new
+    o.string = "19101101"
+
+    d = Date.parse(o)
+    d.should == Date.civil(1910, 11, 1)
+
+    # parse should not modify string value
+    o.to_str.should == "19101101"
   end
 end
 
@@ -76,7 +93,7 @@ describe "Date#parse with '.' separator" do
     @sep = '.'
   end
 
-  it_should_behave_like "date_parse"
+  it_should_behave_like :date_parse
 end
 
 describe "Date#parse with '/' separator" do
@@ -84,7 +101,7 @@ describe "Date#parse with '/' separator" do
     @sep = '/'
   end
 
-  it_should_behave_like "date_parse"
+  it_should_behave_like :date_parse
 end
 
 describe "Date#parse with ' ' separator" do
@@ -92,7 +109,7 @@ describe "Date#parse with ' ' separator" do
     @sep = ' '
   end
 
-  it_should_behave_like "date_parse"
+  it_should_behave_like :date_parse
 end
 
 describe "Date#parse with '/' separator US-style" do
@@ -100,7 +117,7 @@ describe "Date#parse with '/' separator US-style" do
     @sep = '/'
   end
 
-  it_should_behave_like "date_parse_us"
+  it_should_behave_like :date_parse_us
 end
 
 describe "Date#parse with '-' separator EU-style" do
@@ -108,7 +125,7 @@ describe "Date#parse with '-' separator EU-style" do
     @sep = '-'
   end
 
-  it_should_behave_like "date_parse_eu"
+  it_should_behave_like :date_parse_eu
 end
 
 describe "Date#parse(.)" do
diff --git a/spec/ruby/library/date/plus_spec.rb b/spec/ruby/library/date/plus_spec.rb
index 0cb99fd4ca..6179370fca 100644
--- a/spec/ruby/library/date/plus_spec.rb
+++ b/spec/ruby/library/date/plus_spec.rb
@@ -15,6 +15,6 @@ describe "Date#+" do
   end
 
   it "raises TypeError if argument is not Numeric" do
-    -> { Date.today + Date.today }.should raise_error(TypeError)
+    -> { Date.today + Date.today }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/date/rfc3339_spec.rb b/spec/ruby/library/date/rfc3339_spec.rb
new file mode 100644
index 0000000000..a8711d47b2
--- /dev/null
+++ b/spec/ruby/library/date/rfc3339_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+require 'date'
+
+describe "Date.rfc3339" do
+  it "needs to be reviewed for spec completeness"
+end
+
+describe "Date._rfc3339" do
+  it "returns an empty hash if the argument is a invalid Date" do
+    h = Date._rfc3339('invalid')
+    h.should == {}
+  end
+end
diff --git a/spec/ruby/library/date/saturday_spec.rb b/spec/ruby/library/date/saturday_spec.rb
index 1527b71d00..29f8267a2b 100644
--- a/spec/ruby/library/date/saturday_spec.rb
+++ b/spec/ruby/library/date/saturday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#saturday?" do
   it "should be saturday" do
-    Date.new(2000, 1, 1).saturday?.should be_true
+    Date.new(2000, 1, 1).saturday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/shared/civil.rb b/spec/ruby/library/date/shared/civil.rb
index 4c8ba23622..4499cdf8e9 100644
--- a/spec/ruby/library/date/shared/civil.rb
+++ b/spec/ruby/library/date/shared/civil.rb
@@ -5,7 +5,7 @@ describe :date_civil, shared: true do
     d.year.should == -4712
     d.month.should == 1
     d.day.should == 1
-    d.julian?.should == true
+    d.should.julian?
     d.jd.should == 0
   end
 
@@ -14,7 +14,7 @@ describe :date_civil, shared: true do
     d.year.should == 2000
     d.month.should == 3
     d.day.should == 5
-    d.julian?.should == false
+    d.should_not.julian?
     d.jd.should == 2451609
 
     # Should also work with years far in the past and future
@@ -23,27 +23,27 @@ describe :date_civil, shared: true do
     d.year.should == -9000
     d.month.should == 7
     d.day.should == 5
-    d.julian?.should == true
+    d.should.julian?
     d.jd.should == -1566006
 
     d = Date.send(@method, 9000, 10, 14)
     d.year.should == 9000
     d.month.should == 10
     d.day.should == 14
-    d.julian?.should == false
+    d.should_not.julian?
     d.jd.should == 5008529
 
   end
 
   it "doesn't create dates for invalid arguments" do
-    -> { Date.send(@method, 2000, 13, 31) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2000, 12, 32) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2000,  2, 30) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 1900,  2, 29) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2000,  2, 29) }.should_not raise_error(ArgumentError)
-
-    -> { Date.send(@method, 1582, 10, 14) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 1582, 10, 15) }.should_not raise_error(ArgumentError)
+    -> { Date.send(@method, 2000, 13, 31) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2000, 12, 32) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2000,  2, 30) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 1900,  2, 29) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2000,  2, 29) }.should_not.raise(ArgumentError)
+
+    -> { Date.send(@method, 1582, 10, 14) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 1582, 10, 15) }.should_not.raise(ArgumentError)
 
   end
 
diff --git a/spec/ruby/library/date/shared/commercial.rb b/spec/ruby/library/date/shared/commercial.rb
index 39c9af47b6..f53d83235a 100644
--- a/spec/ruby/library/date/shared/commercial.rb
+++ b/spec/ruby/library/date/shared/commercial.rb
@@ -25,15 +25,15 @@ describe :date_commercial, shared: true do
   end
 
   it "creates only Date objects for valid weeks" do
-    -> { Date.send(@method, 2004, 53, 1) }.should_not raise_error(ArgumentError)
-    -> { Date.send(@method, 2004, 53, 0) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2004, 53, 8) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2004, 54, 1) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2004,  0, 1) }.should raise_error(ArgumentError)
+    -> { Date.send(@method, 2004, 53, 1) }.should_not.raise(ArgumentError)
+    -> { Date.send(@method, 2004, 53, 0) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2004, 53, 8) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2004, 54, 1) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2004,  0, 1) }.should.raise(ArgumentError)
 
-    -> { Date.send(@method, 2003, 52, 1) }.should_not raise_error(ArgumentError)
-    -> { Date.send(@method, 2003, 53, 1) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2003, 52, 0) }.should raise_error(ArgumentError)
-    -> { Date.send(@method, 2003, 52, 8) }.should raise_error(ArgumentError)
+    -> { Date.send(@method, 2003, 52, 1) }.should_not.raise(ArgumentError)
+    -> { Date.send(@method, 2003, 53, 1) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2003, 52, 0) }.should.raise(ArgumentError)
+    -> { Date.send(@method, 2003, 52, 8) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/date/shared/month.rb b/spec/ruby/library/date/shared/month.rb
new file mode 100644
index 0000000000..5fcb2cbeb0
--- /dev/null
+++ b/spec/ruby/library/date/shared/month.rb
@@ -0,0 +1,6 @@
+describe :date_month, shared: true do
+  it "returns the month" do
+    m = Date.new(2000, 7, 1).send(@method)
+    m.should == 7
+  end
+end
diff --git a/spec/ruby/library/date/shared/new_bang.rb b/spec/ruby/library/date/shared/new_bang.rb
deleted file mode 100644
index 90f1b432f0..0000000000
--- a/spec/ruby/library/date/shared/new_bang.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-describe :date_new_bang, shared: true do
-
-  it "returns a new Date object set to Astronomical Julian Day 0 if no arguments passed" do
-    d = Date.send(@method)
-    d.ajd.should == 0
-  end
-
-  it "accepts astronomical julian day number, offset as a fraction of a day and returns a new Date object" do
-    d = Date.send(@method, 10, 0.5)
-    d.ajd.should == 10
-    d.jd.should == 11
-  end
-
-end
diff --git a/spec/ruby/library/date/shared/parse.rb b/spec/ruby/library/date/shared/parse.rb
index 1015285e04..40af908386 100644
--- a/spec/ruby/library/date/shared/parse.rb
+++ b/spec/ruby/library/date/shared/parse.rb
@@ -13,7 +13,7 @@ describe :date_parse, shared: true do
     d.day.should == 23
   end
 
-  it "can parse a 'mmm DD YYYY' string into a Date object" do
+  it "can parse a 'DD mmm YYYY' string into a Date object" do
     d = Date.parse("23#{@sep}feb#{@sep}2008")
     d.year.should == 2008
     d.month.should == 2
@@ -42,7 +42,7 @@ describe :date_parse, shared: true do
     d.should == Date.civil(2005, 11, 5)
   end
 
-  it "can parse a year, day and month name into a Date object" do
+  it "can parse a day, month name and year into a Date object" do
     d = Date.parse("5th#{@sep}november#{@sep}2005")
     d.should == Date.civil(2005, 11, 5)
   end
diff --git a/spec/ruby/library/date/shared/parse_eu.rb b/spec/ruby/library/date/shared/parse_eu.rb
index ecb15e3c0e..3819524a57 100644
--- a/spec/ruby/library/date/shared/parse_eu.rb
+++ b/spec/ruby/library/date/shared/parse_eu.rb
@@ -7,28 +7,28 @@ describe :date_parse_eu, shared: true do
     d.day.should == 1
   end
 
-  it "can parse a MM-DD-YYYY string into a Date object" do
+  it "can parse a DD-MM-YYYY string into a Date object" do
     d = Date.parse("10#{@sep}01#{@sep}2007")
     d.year.should == 2007
     d.month.should == 1
     d.day.should == 10
   end
 
-  it "can parse a MM-DD-YY string into a Date object" do
+  it "can parse a YY-MM-DD string into a Date object" do
     d = Date.parse("10#{@sep}01#{@sep}07")
     d.year.should == 2010
     d.month.should == 1
     d.day.should == 7
   end
 
-  it "can parse a MM-DD-YY string into a Date object NOT using the year digits as 20XX" do
+  it "can parse a YY-MM-DD string into a Date object NOT using the year digits as 20XX" do
     d = Date.parse("10#{@sep}01#{@sep}07", false)
     d.year.should == 10
     d.month.should == 1
     d.day.should == 7
   end
 
-  it "can parse a MM-DD-YY string into a Date object using the year digits as 20XX" do
+  it "can parse a YY-MM-DD string into a Date object using the year digits as 20XX" do
     d = Date.parse("10#{@sep}01#{@sep}07", true)
     d.year.should == 2010
     d.month.should == 1
diff --git a/spec/ruby/library/date/shared/parse_us.rb b/spec/ruby/library/date/shared/parse_us.rb
index 7be62b1af1..17e2fc96c1 100644
--- a/spec/ruby/library/date/shared/parse_us.rb
+++ b/spec/ruby/library/date/shared/parse_us.rb
@@ -6,28 +6,28 @@ describe :date_parse_us, shared: true do
     d.day.should == 1
   end
 
-  it "parses a MM#{@sep}DD#{@sep}YYYY string into a Date object" do
+  it "parses a DD#{@sep}MM#{@sep}YYYY string into a Date object" do
     d = Date.parse("10#{@sep}01#{@sep}2007")
     d.year.should == 2007
     d.month.should == 1
     d.day.should == 10
   end
 
-  it "parses a MM#{@sep}DD#{@sep}YY string into a Date object" do
+  it "parses a YY#{@sep}MM#{@sep}DD string into a Date object" do
     d = Date.parse("10#{@sep}01#{@sep}07")
     d.year.should == 2010
     d.month.should == 1
     d.day.should == 7
   end
 
-  it "parses a MM#{@sep}DD#{@sep}YY string into a Date object NOT using the year digits as 20XX" do
+  it "parses a YY#{@sep}MM#{@sep}DD string into a Date object NOT using the year digits as 20XX" do
     d = Date.parse("10#{@sep}01#{@sep}07", false)
     d.year.should == 10
     d.month.should == 1
     d.day.should == 7
   end
 
-  it "parses a MM#{@sep}DD#{@sep}YY string into a Date object using the year digits as 20XX" do
+  it "parses a YY#{@sep}MM#{@sep}DD string into a Date object using the year digits as 20XX" do
     d = Date.parse("10#{@sep}01#{@sep}07", true)
     d.year.should == 2010
     d.month.should == 1
diff --git a/spec/ruby/library/date/shared/valid_civil.rb b/spec/ruby/library/date/shared/valid_civil.rb
index 545c207bbe..425fee4d2d 100644
--- a/spec/ruby/library/date/shared/valid_civil.rb
+++ b/spec/ruby/library/date/shared/valid_civil.rb
@@ -9,8 +9,8 @@ describe :date_valid_civil?, shared: true do
   #  31
 
   it "returns true if it is a valid civil date" do
-    Date.send(@method, 1582, 10, 15).should be_true
-    Date.send(@method, 1582, 10, 14, Date::ENGLAND).should be_true
+    Date.send(@method, 1582, 10, 15).should == true
+    Date.send(@method, 1582, 10, 14, Date::ENGLAND).should == true
   end
 
   it "returns false if it is not a valid civil date" do
@@ -24,13 +24,13 @@ describe :date_valid_civil?, shared: true do
     #   -15 -14 -13 -12 -11 -10  -9
     #    -8  -7  -6  -5  -4  -3  -2
     #    -1
-    Date.send(@method, 1582, -3, -22).should be_false
-    Date.send(@method, 1582, -3, -21).should be_true
-    Date.send(@method, 1582, -3, -18).should be_true
-    Date.send(@method, 1582, -3, -17).should be_true
+    Date.send(@method, 1582, -3, -22).should == false
+    Date.send(@method, 1582, -3, -21).should == true
+    Date.send(@method, 1582, -3, -18).should == true
+    Date.send(@method, 1582, -3, -17).should == true
 
-    Date.send(@method, 2007, -11, -10).should be_true
-    Date.send(@method, 2008, -11, -10).should be_true
+    Date.send(@method, 2007, -11, -10).should == true
+    Date.send(@method, 2008, -11, -10).should == true
   end
 
 end
diff --git a/spec/ruby/library/date/shared/valid_commercial.rb b/spec/ruby/library/date/shared/valid_commercial.rb
index 117dfe1d3d..573b851fdd 100644
--- a/spec/ruby/library/date/shared/valid_commercial.rb
+++ b/spec/ruby/library/date/shared/valid_commercial.rb
@@ -6,16 +6,16 @@ describe :date_valid_commercial?, shared: true do
     # 39:  1  2  3  4  5  6  7
     # 40:  1  2  3  4  5  6  7
     # 41:  1  2  3  4  5  6  7
-    Date.send(@method, 1582, 39, 4).should be_true
-    Date.send(@method, 1582, 39, 5).should be_true
-    Date.send(@method, 1582, 41, 4).should be_true
-    Date.send(@method, 1582, 41, 5).should be_true
-    Date.send(@method, 1582, 41, 4, Date::ENGLAND).should be_true
-    Date.send(@method, 1752, 37, 4, Date::ENGLAND).should be_true
+    Date.send(@method, 1582, 39, 4).should == true
+    Date.send(@method, 1582, 39, 5).should == true
+    Date.send(@method, 1582, 41, 4).should == true
+    Date.send(@method, 1582, 41, 5).should == true
+    Date.send(@method, 1582, 41, 4, Date::ENGLAND).should == true
+    Date.send(@method, 1752, 37, 4, Date::ENGLAND).should == true
   end
 
   it "returns false it is not a valid commercial date" do
-    Date.send(@method, 1999, 53, 1).should be_false
+    Date.send(@method, 1999, 53, 1).should == false
   end
 
   it "handles negative week and day numbers" do
@@ -24,11 +24,11 @@ describe :date_valid_commercial?, shared: true do
     # -12: -7 -6 -5 -4 -3 -2 -1
     # -11: -7 -6 -5 -4 -3 -2 -1
     # -10: -7 -6 -5 -4 -3 -2 -1
-    Date.send(@method, 1582, -12, -4).should be_true
-    Date.send(@method, 1582, -12, -3).should be_true
-    Date.send(@method, 2007, -44, -2).should be_true
-    Date.send(@method, 2008, -44, -2).should be_true
-    Date.send(@method, 1999, -53, -1).should be_false
+    Date.send(@method, 1582, -12, -4).should == true
+    Date.send(@method, 1582, -12, -3).should == true
+    Date.send(@method, 2007, -44, -2).should == true
+    Date.send(@method, 2008, -44, -2).should == true
+    Date.send(@method, 1999, -53, -1).should == false
   end
 
 end
diff --git a/spec/ruby/library/date/shared/valid_jd.rb b/spec/ruby/library/date/shared/valid_jd.rb
index bd71f5abba..0c01710208 100644
--- a/spec/ruby/library/date/shared/valid_jd.rb
+++ b/spec/ruby/library/date/shared/valid_jd.rb
@@ -1,15 +1,20 @@
 describe :date_valid_jd?, shared: true do
-  it "returns true if passed any value other than nil" do
-    Date.send(@method, -100).should be_true
-    Date.send(@method, :number).should be_true
-    Date.send(@method, Rational(1,2)).should be_true
+  it "returns true if passed a number value" do
+    Date.send(@method, -100).should == true
+    Date.send(@method, 100.0).should == true
+    Date.send(@method, 2**100).should == true
+    Date.send(@method, Rational(1,2)).should == true
   end
 
   it "returns false if passed nil" do
-    Date.send(@method, nil).should be_false
+    Date.send(@method, nil).should == false
   end
 
-  it "returns true if passed false" do
-    Date.send(@method, false).should be_true
+  it "returns false if passed symbol" do
+    Date.send(@method, :number).should == false
+  end
+
+  it "returns false if passed false" do
+    Date.send(@method, false).should == false
   end
 end
diff --git a/spec/ruby/library/date/strftime_spec.rb b/spec/ruby/library/date/strftime_spec.rb
index 9d298e42e6..1b93a8d1b2 100644
--- a/spec/ruby/library/date/strftime_spec.rb
+++ b/spec/ruby/library/date/strftime_spec.rb
@@ -1,5 +1,7 @@
+require_relative "../../spec_helper"
 require 'date'
 require_relative '../../shared/time/strftime_for_date'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
 
 describe "Date#strftime" do
   before :all do
@@ -21,10 +23,9 @@ describe "Date#strftime" do
     @date.strftime("%Z").should == "+00:00"
   end
 
-  # %v is %e-%b-%Y for Date/DateTime
   it "should be able to show the commercial week" do
-    @date.strftime("%v").should == " 9-Apr-2000"
-    @date.strftime("%v").should == @date.strftime('%e-%b-%Y')
+    @date.strftime("%v").should == " 9-APR-2000"
+    @date.strftime("%v").should != @date.strftime('%e-%b-%Y')
   end
 
   # additional conversion specifiers only in Date/DateTime
diff --git a/spec/ruby/library/date/sunday_spec.rb b/spec/ruby/library/date/sunday_spec.rb
index c3a817fa86..548f36a4f0 100644
--- a/spec/ruby/library/date/sunday_spec.rb
+++ b/spec/ruby/library/date/sunday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#sunday?" do
   it "should be sunday" do
-    Date.new(2000, 1, 2).sunday?.should be_true
+    Date.new(2000, 1, 2).sunday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/thursday_spec.rb b/spec/ruby/library/date/thursday_spec.rb
index 74b5f40365..4df3b9103a 100644
--- a/spec/ruby/library/date/thursday_spec.rb
+++ b/spec/ruby/library/date/thursday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#thursday?" do
   it "should be thursday" do
-    Date.new(2000, 1, 6).thursday?.should be_true
+    Date.new(2000, 1, 6).thursday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/time/to_date_spec.rb b/spec/ruby/library/date/time/to_date_spec.rb
new file mode 100644
index 0000000000..f9132da289
--- /dev/null
+++ b/spec/ruby/library/date/time/to_date_spec.rb
@@ -0,0 +1,42 @@
+
+require_relative '../../../spec_helper'
+require 'time'
+
+describe "Time#to_date" do
+  it "yields accurate julian date for ambiguous pre-Gregorian reform value" do
+    Time.utc(1582, 10, 4).to_date.jd.should == Date::ITALY - 11 # 2299150j
+  end
+
+  it "yields accurate julian date for Julian-Gregorian gap value" do
+    Time.utc(1582, 10, 14).to_date.jd.should == Date::ITALY - 1 # 2299160j
+  end
+
+  it "yields accurate julian date for post-Gregorian reform value" do
+    Time.utc(1582, 10, 15).to_date.jd.should == Date::ITALY # 2299161j
+  end
+
+  it "yields same julian day regardless of UTC time value" do
+    Time.utc(1582, 10, 15, 00, 00, 00).to_date.jd.should == Date::ITALY
+    Time.utc(1582, 10, 15, 23, 59, 59).to_date.jd.should == Date::ITALY
+  end
+
+  it "yields same julian day regardless of local time or zone" do
+
+    with_timezone("Pacific/Pago_Pago", -11) do
+      Time.local(1582, 10, 15, 00, 00, 00).to_date.jd.should == Date::ITALY
+      Time.local(1582, 10, 15, 23, 59, 59).to_date.jd.should == Date::ITALY
+    end
+
+    with_timezone("Asia/Kamchatka", +12) do
+      Time.local(1582, 10, 15, 00, 00, 00).to_date.jd.should == Date::ITALY
+      Time.local(1582, 10, 15, 23, 59, 59).to_date.jd.should == Date::ITALY
+    end
+
+  end
+
+  it "yields date with default Calendar reform day" do
+    Time.utc(1582, 10,  4).to_date.start.should == Date::ITALY
+    Time.utc(1582, 10, 14).to_date.start.should == Date::ITALY
+    Time.utc(1582, 10, 15).to_date.start.should == Date::ITALY
+  end
+end
diff --git a/spec/ruby/library/date/today_spec.rb b/spec/ruby/library/date/today_spec.rb
index 7c6ebc9cb4..4be8d8e931 100644
--- a/spec/ruby/library/date/today_spec.rb
+++ b/spec/ruby/library/date/today_spec.rb
@@ -3,7 +3,7 @@ require 'date'
 
 describe "Date.today" do
   it "returns a Date object" do
-    Date.today.should be_kind_of Date
+    Date.today.should.is_a? Date
   end
 
   it "sets Date object to the current date" do
diff --git a/spec/ruby/library/date/tuesday_spec.rb b/spec/ruby/library/date/tuesday_spec.rb
index 052837b54e..db31387aed 100644
--- a/spec/ruby/library/date/tuesday_spec.rb
+++ b/spec/ruby/library/date/tuesday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#tuesday?" do
   it "should be tuesday" do
-    Date.new(2000, 1, 4).tuesday?.should be_true
+    Date.new(2000, 1, 4).tuesday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/wednesday_spec.rb b/spec/ruby/library/date/wednesday_spec.rb
index e80ec23dd2..4bbeead5b8 100644
--- a/spec/ruby/library/date/wednesday_spec.rb
+++ b/spec/ruby/library/date/wednesday_spec.rb
@@ -3,6 +3,6 @@ require 'date'
 
 describe "Date#wednesday?" do
   it "should be wednesday" do
-    Date.new(2000, 1, 5).wednesday?.should be_true
+    Date.new(2000, 1, 5).wednesday?.should == true
   end
 end
diff --git a/spec/ruby/library/date/yday_spec.rb b/spec/ruby/library/date/yday_spec.rb
index cfb174a4c2..7dd42e52a5 100644
--- a/spec/ruby/library/date/yday_spec.rb
+++ b/spec/ruby/library/date/yday_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
+require_relative '../../shared/time/yday'
 require 'date'
 
 describe "Date#yday" do
-  it "needs to be reviewed for spec completeness"
+  it_behaves_like :time_yday, -> year, month, day { Date.new(year, month, day).yday }
 end
diff --git a/spec/ruby/library/datetime/deconstruct_keys_spec.rb b/spec/ruby/library/datetime/deconstruct_keys_spec.rb
new file mode 100644
index 0000000000..07a7bda881
--- /dev/null
+++ b/spec/ruby/library/datetime/deconstruct_keys_spec.rb
@@ -0,0 +1,44 @@
+require_relative '../../spec_helper'
+require 'date'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
+
+describe "DateTime#deconstruct_keys" do
+  it "returns whole hash for nil as an argument" do
+    d = DateTime.new(2022, 10, 5, 13, 30)
+    res = { year: 2022, month: 10, day: 5, yday: 278, wday: 3, hour: 13,
+            min: 30, sec: 0, sec_fraction: (0/1), zone: "+00:00" }
+    d.deconstruct_keys(nil).should == res
+  end
+
+  it "returns only specified keys" do
+    d = DateTime.new(2022, 10, 5, 13, 39)
+    d.deconstruct_keys([:zone, :hour]).should == { zone: "+00:00", hour: 13 }
+  end
+
+  it "requires one argument" do
+    -> {
+      DateTime.new(2022, 10, 5, 13, 30).deconstruct_keys
+    }.should.raise(ArgumentError)
+  end
+
+  it "it raises error when argument is neither nil nor array" do
+    d = DateTime.new(2022, 10, 5, 13, 30)
+
+    -> { d.deconstruct_keys(1) }.should.raise(TypeError, "wrong argument type Integer (expected Array or nil)")
+    -> { d.deconstruct_keys("asd") }.should.raise(TypeError, "wrong argument type String (expected Array or nil)")
+    -> { d.deconstruct_keys(:x) }.should.raise(TypeError, "wrong argument type Symbol (expected Array or nil)")
+    -> { d.deconstruct_keys({}) }.should.raise(TypeError, "wrong argument type Hash (expected Array or nil)")
+  end
+
+  it "returns {} when passed []" do
+    DateTime.new(2022, 10, 5, 13, 30).deconstruct_keys([]).should == {}
+  end
+
+  it "ignores non-Symbol keys" do
+    DateTime.new(2022, 10, 5, 13, 30).deconstruct_keys(['year', []]).should == {}
+  end
+
+  it "ignores not existing Symbol keys" do
+    DateTime.new(2022, 10, 5, 13, 30).deconstruct_keys([:year, :a]).should == { year: 2022 }
+  end
+end
diff --git a/spec/ruby/library/datetime/hour_spec.rb b/spec/ruby/library/datetime/hour_spec.rb
index 8efd5f92f0..383a85fe60 100644
--- a/spec/ruby/library/datetime/hour_spec.rb
+++ b/spec/ruby/library/datetime/hour_spec.rb
@@ -15,23 +15,23 @@ describe "DateTime#hour" do
   end
 
   it "raises an error for Rational" do
-    -> { new_datetime(hour: 1 + Rational(1,2)) }.should raise_error(ArgumentError)
+    -> { new_datetime(hour: 1 + Rational(1,2)) }.should.raise(ArgumentError)
   end
 
   it "raises an error for Float" do
-    -> { new_datetime(hour: 1.5).hour }.should raise_error(ArgumentError)
+    -> { new_datetime(hour: 1.5).hour }.should.raise(ArgumentError)
   end
 
   it "raises an error for Rational" do
-    -> { new_datetime(day: 1 + Rational(1,2)) }.should raise_error(ArgumentError)
+    -> { new_datetime(day: 1 + Rational(1,2)) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the hour is smaller than -24" do
-    -> { new_datetime(hour: -25) }.should raise_error(ArgumentError)
+    -> { new_datetime(hour: -25) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the hour is larger than 24" do
-    -> { new_datetime(hour: 25) }.should raise_error(ArgumentError)
+    -> { new_datetime(hour: 25) }.should.raise(ArgumentError)
   end
 
   it "raises an error for hour fractions smaller than -24" do
diff --git a/spec/ruby/library/datetime/new_spec.rb b/spec/ruby/library/datetime/new_spec.rb
index 6a4dced384..2b3c3f156c 100644
--- a/spec/ruby/library/datetime/new_spec.rb
+++ b/spec/ruby/library/datetime/new_spec.rb
@@ -47,6 +47,6 @@ describe "DateTime.new" do
   end
 
   it "raises an error on invalid arguments" do
-    -> { new_datetime(minute: 999) }.should raise_error(ArgumentError)
+    -> { new_datetime(minute: 999) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/datetime/now_spec.rb b/spec/ruby/library/datetime/now_spec.rb
index 9f22153c15..5c0411c2be 100644
--- a/spec/ruby/library/datetime/now_spec.rb
+++ b/spec/ruby/library/datetime/now_spec.rb
@@ -3,7 +3,7 @@ require 'date'
 
 describe "DateTime.now" do
   it "creates an instance of DateTime" do
-    DateTime.now.should be_an_instance_of(DateTime)
+    DateTime.now.should.instance_of?(DateTime)
   end
 
   it "sets the current date" do
diff --git a/spec/ruby/library/datetime/parse_spec.rb b/spec/ruby/library/datetime/parse_spec.rb
index e9bf4e2ed1..0a965273a0 100644
--- a/spec/ruby/library/datetime/parse_spec.rb
+++ b/spec/ruby/library/datetime/parse_spec.rb
@@ -20,7 +20,7 @@ describe "DateTime.parse" do
 
   # Specs using numbers
   it "throws an argument error for a single digit" do
-    ->{ DateTime.parse("1") }.should raise_error(ArgumentError)
+    ->{ DateTime.parse("1") }.should.raise(ArgumentError)
   end
 
   it "parses DD as month day number" do
@@ -54,23 +54,23 @@ describe "DateTime.parse" do
     end
 
     it "throws an argument error for invalid month values" do
-      ->{DateTime.parse("2012-13-08T15:43:59")}.should raise_error(ArgumentError)
+      ->{DateTime.parse("2012-13-08T15:43:59")}.should.raise(ArgumentError)
     end
 
     it "throws an argument error for invalid day values" do
-      ->{DateTime.parse("2012-12-32T15:43:59")}.should raise_error(ArgumentError)
+      ->{DateTime.parse("2012-12-32T15:43:59")}.should.raise(ArgumentError)
     end
 
     it "throws an argument error for invalid hour values" do
-      ->{DateTime.parse("2012-12-31T25:43:59")}.should raise_error(ArgumentError)
+      ->{DateTime.parse("2012-12-31T25:43:59")}.should.raise(ArgumentError)
     end
 
     it "throws an argument error for invalid minute values" do
-      ->{DateTime.parse("2012-12-31T25:43:59")}.should raise_error(ArgumentError)
+      ->{DateTime.parse("2012-12-31T25:43:59")}.should.raise(ArgumentError)
     end
 
     it "throws an argument error for invalid second values" do
-      ->{DateTime.parse("2012-11-08T15:43:61")}.should raise_error(ArgumentError)
+      ->{DateTime.parse("2012-11-08T15:43:61")}.should.raise(ArgumentError)
     end
 
   end
diff --git a/spec/ruby/library/datetime/rfc2822_spec.rb b/spec/ruby/library/datetime/rfc2822_spec.rb
index 70bfca60b4..11b79a1e84 100644
--- a/spec/ruby/library/datetime/rfc2822_spec.rb
+++ b/spec/ruby/library/datetime/rfc2822_spec.rb
@@ -3,4 +3,8 @@ require 'date'
 
 describe "DateTime.rfc2822" do
   it "needs to be reviewed for spec completeness"
+
+  it "raises DateError if passed nil" do
+    -> { DateTime.rfc2822(nil) }.should.raise(Date::Error, "invalid date")
+  end
 end
diff --git a/spec/ruby/library/datetime/shared/min.rb b/spec/ruby/library/datetime/shared/min.rb
index a35b839281..04e5f3457a 100644
--- a/spec/ruby/library/datetime/shared/min.rb
+++ b/spec/ruby/library/datetime/shared/min.rb
@@ -14,23 +14,23 @@ describe :datetime_min, shared: true do
   end
 
   it "raises an error for Rational" do
-    -> { new_datetime minute: 5 + Rational(1,2) }.should raise_error(ArgumentError)
+    -> { new_datetime minute: 5 + Rational(1,2) }.should.raise(ArgumentError)
   end
 
   it "raises an error for Float" do
-    -> { new_datetime minute: 5.5 }.should raise_error(ArgumentError)
+    -> { new_datetime minute: 5.5 }.should.raise(ArgumentError)
   end
 
   it "raises an error for Rational" do
-    -> { new_datetime(hour: 2 + Rational(1,2)) }.should raise_error(ArgumentError)
+    -> { new_datetime(hour: 2 + Rational(1,2)) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the minute is smaller than -60" do
-    -> { new_datetime(minute: -61) }.should raise_error(ArgumentError)
+    -> { new_datetime(minute: -61) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the minute is greater or equal than 60" do
-    -> { new_datetime(minute: 60) }.should raise_error(ArgumentError)
+    -> { new_datetime(minute: 60) }.should.raise(ArgumentError)
   end
 
   it "raises an error for minute fractions smaller than -60" do
diff --git a/spec/ruby/library/datetime/shared/sec.rb b/spec/ruby/library/datetime/shared/sec.rb
index 60009213aa..5af5db4fb2 100644
--- a/spec/ruby/library/datetime/shared/sec.rb
+++ b/spec/ruby/library/datetime/shared/sec.rb
@@ -23,15 +23,15 @@ describe :datetime_sec, shared: true do
   end
 
   it "raises an error when minute is given as a rational" do
-    -> { new_datetime(minute: 5 + Rational(1,2)) }.should raise_error(ArgumentError)
+    -> { new_datetime(minute: 5 + Rational(1,2)) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the second is smaller than -60" do
-    -> { new_datetime(second: -61) }.should raise_error(ArgumentError)
+    -> { new_datetime(second: -61) }.should.raise(ArgumentError)
   end
 
   it "raises an error, when the second is greater or equal than 60" do
-    -> { new_datetime(second: 60) }.should raise_error(ArgumentError)
+    -> { new_datetime(second: 60) }.should.raise(ArgumentError)
   end
 
   it "raises an error for second fractions smaller than -60" do
diff --git a/spec/ruby/library/datetime/strftime_spec.rb b/spec/ruby/library/datetime/strftime_spec.rb
index 1c925f92eb..a07cc9c1aa 100644
--- a/spec/ruby/library/datetime/strftime_spec.rb
+++ b/spec/ruby/library/datetime/strftime_spec.rb
@@ -1,6 +1,8 @@
+require_relative '../../spec_helper'
 require 'date'
 require_relative '../../shared/time/strftime_for_date'
 require_relative '../../shared/time/strftime_for_time'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
 
 describe "DateTime#strftime" do
   before :all do
@@ -31,10 +33,9 @@ describe "DateTime#strftime" do
     @time.strftime("%Z").should == "+00:00"
   end
 
-  # %v is %e-%b-%Y for Date/DateTime
   it "should be able to show the commercial week" do
-    @time.strftime("%v").should == " 3-Feb-2001"
-    @time.strftime("%v").should == @time.strftime('%e-%b-%Y')
+    @time.strftime("%v").should == " 3-FEB-2001"
+    @time.strftime("%v").should != @time.strftime('%e-%b-%Y')
   end
 
   # additional conversion specifiers only in Date/DateTime
diff --git a/spec/ruby/library/datetime/time/to_datetime_spec.rb b/spec/ruby/library/datetime/time/to_datetime_spec.rb
new file mode 100644
index 0000000000..5589725238
--- /dev/null
+++ b/spec/ruby/library/datetime/time/to_datetime_spec.rb
@@ -0,0 +1,40 @@
+require_relative '../../../spec_helper'
+require 'time'
+require 'date'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
+
+describe "Time#to_datetime" do
+  it "returns a DateTime representing the same instant" do
+    time = Time.utc(2012, 12, 31, 23, 58, 59)
+    datetime = time.to_datetime
+    datetime.year.should == 2012
+    datetime.month.should == 12
+    datetime.day.should == 31
+    datetime.hour.should == 23
+    datetime.min.should == 58
+    datetime.sec.should == 59
+  end
+
+  it "returns a DateTime representing the same instant before Gregorian" do
+    time = Time.utc(1582, 10, 14, 23, 58, 59)
+    datetime = time.to_datetime
+    datetime.year.should == 1582
+    datetime.month.should == 10
+    datetime.day.should == 4
+    datetime.hour.should == 23
+    datetime.min.should == 58
+    datetime.sec.should == 59
+  end
+
+  it "roundtrips" do
+    time = Time.utc(3, 12, 31, 23, 58, 59)
+    datetime = time.to_datetime
+    datetime.to_time.utc.should == time
+  end
+
+  it "yields a DateTime with the default Calendar reform day" do
+    Time.utc(1582, 10,  4, 1, 2, 3).to_datetime.start.should == Date::ITALY
+    Time.utc(1582, 10, 14, 1, 2, 3).to_datetime.start.should == Date::ITALY
+    Time.utc(1582, 10, 15, 1, 2, 3).to_datetime.start.should == Date::ITALY
+  end
+end
diff --git a/spec/ruby/library/datetime/to_date_spec.rb b/spec/ruby/library/datetime/to_date_spec.rb
index 48c05e7fed..31ccf5ae98 100644
--- a/spec/ruby/library/datetime/to_date_spec.rb
+++ b/spec/ruby/library/datetime/to_date_spec.rb
@@ -4,7 +4,7 @@ require 'date'
 describe "DateTime#to_date" do
   it "returns an instance of Date" do
     dt = DateTime.new(2012, 12, 24, 12, 23, 00, '+05:00')
-    dt.to_date.should be_kind_of(Date)
+    dt.to_date.should.is_a?(Date)
   end
 
   it "maintains the same year" do
diff --git a/spec/ruby/library/datetime/to_s_spec.rb b/spec/ruby/library/datetime/to_s_spec.rb
index 175fb807f4..ed0746f42b 100644
--- a/spec/ruby/library/datetime/to_s_spec.rb
+++ b/spec/ruby/library/datetime/to_s_spec.rb
@@ -4,7 +4,7 @@ require 'date'
 describe "DateTime#to_s" do
   it "returns a new String object" do
     dt = DateTime.new(2012, 12, 24, 1, 2, 3, "+03:00")
-    dt.to_s.should be_kind_of(String)
+    dt.to_s.should.is_a?(String)
   end
 
   it "maintains timezone regardless of local time" do
diff --git a/spec/ruby/library/datetime/to_time_spec.rb b/spec/ruby/library/datetime/to_time_spec.rb
index a11b6e30e1..a3ffc019fb 100644
--- a/spec/ruby/library/datetime/to_time_spec.rb
+++ b/spec/ruby/library/datetime/to_time_spec.rb
@@ -1,16 +1,17 @@
 require_relative '../../spec_helper'
 require 'date'
+date_version = defined?(Date::VERSION) ? Date::VERSION : '3.1.0'
 
 describe "DateTime#to_time" do
   it "yields a new Time object" do
-    DateTime.now.to_time.should be_kind_of(Time)
+    DateTime.now.to_time.should.is_a?(Time)
   end
 
   it "returns a Time representing the same instant" do
-    datetime = DateTime.civil(3, 12, 31, 23, 58, 59)
+    datetime = DateTime.civil(2012, 12, 31, 23, 58, 59)
     time = datetime.to_time.utc
 
-    time.year.should == 3
+    time.year.should == 2012
     time.month.should == 12
     time.day.should == 31
     time.hour.should == 23
@@ -18,6 +19,17 @@ describe "DateTime#to_time" do
     time.sec.should == 59
   end
 
+  it "returns a Time representing the same instant before Gregorian" do
+    datetime = DateTime.civil(1582, 10, 4, 23, 58, 59)
+    time = datetime.to_time.utc
+    time.year.should == 1582
+    time.month.should == 10
+    time.day.should == 14
+    time.hour.should == 23
+    time.min.should == 58
+    time.sec.should == 59
+  end
+
   it "preserves the same time regardless of local time or zone" do
     date = DateTime.new(2012, 12, 24, 12, 23, 00, '+03:00')
 
diff --git a/spec/ruby/library/datetime/yday_spec.rb b/spec/ruby/library/datetime/yday_spec.rb
new file mode 100644
index 0000000000..08a72c6480
--- /dev/null
+++ b/spec/ruby/library/datetime/yday_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/time/yday'
+require 'date'
+
+describe "DateTime#yday" do
+  it_behaves_like :time_yday, -> year, month, day { DateTime.new(year, month, day).yday }
+end
diff --git a/spec/ruby/library/delegate/delegate_class/instance_method_spec.rb b/spec/ruby/library/delegate/delegate_class/instance_method_spec.rb
index 16bf8d734c..19ffc4cf85 100644
--- a/spec/ruby/library/delegate/delegate_class/instance_method_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/instance_method_spec.rb
@@ -9,44 +9,44 @@ describe "DelegateClass.instance_method" do
 
   it "returns a method object for public instance methods of the delegated class" do
     m = @klass.instance_method(:pub)
-    m.should be_an_instance_of(UnboundMethod)
+    m.should.instance_of?(UnboundMethod)
     m.bind(@obj).call.should == :foo
   end
 
   it "returns a method object for protected instance methods of the delegated class" do
     m = @klass.instance_method(:prot)
-    m.should be_an_instance_of(UnboundMethod)
+    m.should.instance_of?(UnboundMethod)
     m.bind(@obj).call.should == :protected
   end
 
   it "raises a NameError for a private instance methods of the delegated class" do
     -> {
       @klass.instance_method(:priv)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "returns a method object for public instance methods of the DelegateClass class" do
     m = @klass.instance_method(:extra)
-    m.should be_an_instance_of(UnboundMethod)
+    m.should.instance_of?(UnboundMethod)
     m.bind(@obj).call.should == :cheese
   end
 
   it "returns a method object for protected instance methods of the DelegateClass class" do
     m = @klass.instance_method(:extra_protected)
-    m.should be_an_instance_of(UnboundMethod)
+    m.should.instance_of?(UnboundMethod)
     m.bind(@obj).call.should == :baz
   end
 
   it "returns a method object for private instance methods of the DelegateClass class" do
     m = @klass.instance_method(:extra_private)
-    m.should be_an_instance_of(UnboundMethod)
+    m.should.instance_of?(UnboundMethod)
     m.bind(@obj).call.should == :bar
   end
 
   it "raises a NameError for an invalid method name" do
     -> {
       @klass.instance_method(:invalid_and_silly_method_name)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
 end
diff --git a/spec/ruby/library/delegate/delegate_class/instance_methods_spec.rb b/spec/ruby/library/delegate/delegate_class/instance_methods_spec.rb
index 6012ff72de..586be56cae 100644
--- a/spec/ruby/library/delegate/delegate_class/instance_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/instance_methods_spec.rb
@@ -7,20 +7,20 @@ describe "DelegateClass.instance_methods" do
   end
 
   it "includes all public methods of the delegated class" do
-    @methods.should include :pub
+    @methods.should.include? :pub
   end
 
   it "includes all protected methods of the delegated class" do
-    @methods.should include :prot
+    @methods.should.include? :prot
   end
 
   it "includes instance methods of the DelegateClass class" do
-    @methods.should include :extra
-    @methods.should include :extra_protected
+    @methods.should.include? :extra
+    @methods.should.include? :extra_protected
   end
 
   it "does not include private methods" do
-    @methods.should_not include :priv
-    @methods.should_not include :extra_private
+    @methods.should_not.include? :priv
+    @methods.should_not.include? :extra_private
   end
 end
diff --git a/spec/ruby/library/delegate/delegate_class/private_instance_methods_spec.rb b/spec/ruby/library/delegate/delegate_class/private_instance_methods_spec.rb
index 06b2115cc5..18ca2a4c88 100644
--- a/spec/ruby/library/delegate/delegate_class/private_instance_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/private_instance_methods_spec.rb
@@ -7,17 +7,17 @@ describe "DelegateClass.private_instance_methods" do
   end
 
   it "does not include any instance methods of the delegated class" do
-    @methods.should_not include :pub
-    @methods.should_not include :prot
-    @methods.should_not include :priv # since these are not forwarded...
+    @methods.should_not.include? :pub
+    @methods.should_not.include? :prot
+    @methods.should_not.include? :priv # since these are not forwarded...
   end
 
   it "includes private instance methods of the DelegateClass class" do
-    @methods.should include :extra_private
+    @methods.should.include? :extra_private
   end
 
   it "does not include public or protected instance methods of the DelegateClass class" do
-    @methods.should_not include :extra
-    @methods.should_not include :extra_protected
+    @methods.should_not.include? :extra
+    @methods.should_not.include? :extra_protected
   end
 end
diff --git a/spec/ruby/library/delegate/delegate_class/protected_instance_methods_spec.rb b/spec/ruby/library/delegate/delegate_class/protected_instance_methods_spec.rb
index ac6659ec1e..d540b45065 100644
--- a/spec/ruby/library/delegate/delegate_class/protected_instance_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/protected_instance_methods_spec.rb
@@ -7,23 +7,23 @@ describe "DelegateClass.protected_instance_methods" do
   end
 
   it "does not include public methods of the delegated class" do
-    @methods.should_not include :pub
+    @methods.should_not.include? :pub
   end
 
   it "includes the protected methods of the delegated class" do
-    @methods.should include :prot
+    @methods.should.include? :prot
   end
 
   it "includes protected instance methods of the DelegateClass class" do
-    @methods.should include :extra_protected
+    @methods.should.include? :extra_protected
   end
 
   it "does not include public instance methods of the DelegateClass class" do
-    @methods.should_not include :extra
+    @methods.should_not.include? :extra
   end
 
   it "does not include private methods" do
-    @methods.should_not include :priv
-    @methods.should_not include :extra_private
+    @methods.should_not.include? :priv
+    @methods.should_not.include? :extra_private
   end
 end
diff --git a/spec/ruby/library/delegate/delegate_class/public_instance_methods_spec.rb b/spec/ruby/library/delegate/delegate_class/public_instance_methods_spec.rb
index 6c0d9bcab1..124b92de82 100644
--- a/spec/ruby/library/delegate/delegate_class/public_instance_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/public_instance_methods_spec.rb
@@ -7,19 +7,19 @@ describe "DelegateClass.public_instance_methods" do
   end
 
   it "includes all public methods of the delegated class" do
-    @methods.should include :pub
+    @methods.should.include? :pub
   end
 
   it "does not include the protected methods of the delegated class" do
-    @methods.should_not include :prot
+    @methods.should_not.include? :prot
   end
 
   it "includes public instance methods of the DelegateClass class" do
-    @methods.should include :extra
+    @methods.should.include? :extra
   end
 
   it "does not include private methods" do
-    @methods.should_not include :priv
-    @methods.should_not include :extra_private
+    @methods.should_not.include? :priv
+    @methods.should_not.include? :extra_private
   end
 end
diff --git a/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb b/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb
index 729cfc96c6..3975e5208b 100644
--- a/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb
+++ b/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require 'delegate'
 
 describe "DelegateClass#respond_to_missing?" do
diff --git a/spec/ruby/library/delegate/delegator/eql_spec.rb b/spec/ruby/library/delegate/delegator/eql_spec.rb
index 3170d5727a..b302bb7016 100644
--- a/spec/ruby/library/delegate/delegator/eql_spec.rb
+++ b/spec/ruby/library/delegate/delegator/eql_spec.rb
@@ -2,45 +2,34 @@ require_relative '../../../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "Delegator#eql?" do
-  ruby_version_is ""..."2.5" do
-    it "is delegated" do
-      base = mock('base')
-      delegator = DelegateSpecs::Delegator.new(base)
-      base.should_receive(:eql?).with(42).and_return(:foo)
-      delegator.eql?(42).should == :foo
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "returns true when compared with same delegator" do
-      base = mock('base')
-      delegator = DelegateSpecs::Delegator.new(base)
+  it "returns true when compared with same delegator" do
+    base = mock('base')
+    delegator = DelegateSpecs::Delegator.new(base)
 
-      delegator.eql?(delegator).should be_true
-    end
+    delegator.eql?(delegator).should == true
+  end
 
-    it "returns true when compared with the inner object" do
-      base = mock('base')
-      delegator = DelegateSpecs::Delegator.new(base)
+  it "returns true when compared with the inner object" do
+    base = mock('base')
+    delegator = DelegateSpecs::Delegator.new(base)
 
-      delegator.eql?(base).should be_true
-    end
+    delegator.eql?(base).should == true
+  end
 
-    it "returns false when compared with the delegator with other object" do
-      base = mock('base')
-      other = mock('other')
-      delegator0 = DelegateSpecs::Delegator.new(base)
-      delegator1 = DelegateSpecs::Delegator.new(other)
+  it "returns false when compared with the delegator with other object" do
+    base = mock('base')
+    other = mock('other')
+    delegator0 = DelegateSpecs::Delegator.new(base)
+    delegator1 = DelegateSpecs::Delegator.new(other)
 
-      delegator0.eql?(delegator1).should be_false
-    end
+    delegator0.eql?(delegator1).should == false
+  end
 
-    it "returns false when compared with the other object" do
-      base = mock('base')
-      other = mock('other')
-      delegator = DelegateSpecs::Delegator.new(base)
+  it "returns false when compared with the other object" do
+    base = mock('base')
+    other = mock('other')
+    delegator = DelegateSpecs::Delegator.new(base)
 
-      delegator.eql?(other).should be_false
-    end
+    delegator.eql?(other).should == false
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/equal_spec.rb b/spec/ruby/library/delegate/delegator/equal_spec.rb
index c8711c74b5..97aabebabe 100644
--- a/spec/ruby/library/delegate/delegator/equal_spec.rb
+++ b/spec/ruby/library/delegate/delegator/equal_spec.rb
@@ -6,8 +6,8 @@ describe "Delegator#equal?" do
     obj = mock('base')
     delegator = DelegateSpecs::Delegator.new(obj)
     obj.should_not_receive(:equal?)
-    delegator.equal?(obj).should be_false
-    delegator.equal?(nil).should be_false
-    delegator.equal?(delegator).should be_true
+    delegator.equal?(obj).should == false
+    delegator.equal?(nil).should == false
+    delegator.equal?(delegator).should == true
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/equal_value_spec.rb b/spec/ruby/library/delegate/delegator/equal_value_spec.rb
index 0c967d5f94..d70aad1e03 100644
--- a/spec/ruby/library/delegate/delegator/equal_value_spec.rb
+++ b/spec/ruby/library/delegate/delegator/equal_value_spec.rb
@@ -9,16 +9,16 @@ describe "Delegator#==" do
 
   it "is not delegated when passed self" do
     @base.should_not_receive(:==)
-    (@delegator == @delegator).should be_true
+    (@delegator == @delegator).should == true
   end
 
   it "is delegated when passed the delegated object" do
     @base.should_receive(:==).and_return(false)
-    (@delegator == @base).should be_false
+    (@delegator == @base).should == false
   end
 
   it "is delegated in general" do
     @base.should_receive(:==).and_return(true)
-    (@delegator == 42).should be_true
+    (@delegator == 42).should == true
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/frozen_spec.rb b/spec/ruby/library/delegate/delegator/frozen_spec.rb
index b3145c54b1..ad87dc8bdf 100644
--- a/spec/ruby/library/delegate/delegator/frozen_spec.rb
+++ b/spec/ruby/library/delegate/delegator/frozen_spec.rb
@@ -10,30 +10,30 @@ describe "Delegator when frozen" do
 
   it "is still readable" do
     @delegate.should == [42, :hello]
-    @delegate.include?("bar").should be_false
+    @delegate.include?("bar").should == false
   end
 
   it "is frozen" do
-    @delegate.frozen?.should be_true
+    @delegate.frozen?.should == true
   end
 
   it "is not writable" do
-    ->{ @delegate[0] += 2 }.should raise_error( RuntimeError )
+    ->{ @delegate[0] += 2 }.should.raise( RuntimeError )
   end
 
   it "creates a frozen clone" do
-    @delegate.clone.frozen?.should be_true
+    @delegate.clone.frozen?.should == true
   end
 
   it "creates an unfrozen dup" do
-    @delegate.dup.frozen?.should be_false
+    @delegate.dup.frozen?.should == false
   end
 
   it "causes mutative calls to raise RuntimeError" do
-    ->{ @delegate.__setobj__("hola!") }.should raise_error( RuntimeError )
+    ->{ @delegate.__setobj__("hola!") }.should.raise( RuntimeError )
   end
 
   it "returns false if only the delegated object is frozen" do
-    DelegateSpecs::Delegator.new([1,2,3].freeze).frozen?.should be_false
+    DelegateSpecs::Delegator.new([1,2,3].freeze).frozen?.should == false
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/marshal_spec.rb b/spec/ruby/library/delegate/delegator/marshal_spec.rb
index 6c75c8f573..2817ac7e0b 100644
--- a/spec/ruby/library/delegate/delegator/marshal_spec.rb
+++ b/spec/ruby/library/delegate/delegator/marshal_spec.rb
@@ -10,7 +10,7 @@ describe "SimpleDelegator" do
   it "can be marshalled" do
     m = Marshal.load(Marshal.dump(@delegate))
     m.class.should == SimpleDelegator
-    (m == @obj).should be_true
+    (m == @obj).should == true
   end
 
   it "can be marshalled with its instance variables intact" do
diff --git a/spec/ruby/library/delegate/delegator/method_spec.rb b/spec/ruby/library/delegate/delegator/method_spec.rb
index 81c8eea710..e41d3b4a53 100644
--- a/spec/ruby/library/delegate/delegator/method_spec.rb
+++ b/spec/ruby/library/delegate/delegator/method_spec.rb
@@ -9,7 +9,7 @@ describe "Delegator#method" do
 
   it "returns a method object for public methods of the delegate object" do
     m = @delegate.method(:pub)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == :foo
   end
 
@@ -18,7 +18,7 @@ describe "Delegator#method" do
       -> {
         @delegate.method(:prot)
       }.should complain(/delegator does not forward private method #prot/)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "raises a NameError for a private methods of the delegate object" do
@@ -26,36 +26,36 @@ describe "Delegator#method" do
       -> {
         @delegate.method(:priv)
       }.should complain(/delegator does not forward private method #priv/)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "returns a method object for public methods of the Delegator class" do
     m = @delegate.method(:extra)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == :cheese
   end
 
   it "returns a method object for protected methods of the Delegator class" do
     m = @delegate.method(:extra_protected)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == :baz
   end
 
   it "returns a method object for private methods of the Delegator class" do
     m = @delegate.method(:extra_private)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == :bar
   end
 
   it "raises a NameError for an invalid method name" do
     -> {
       @delegate.method(:invalid_and_silly_method_name)
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "returns a method that respond_to_missing?" do
     m = @delegate.method(:pub_too)
-    m.should be_an_instance_of(Method)
+    m.should.instance_of?(Method)
     m.call.should == :pub_too
   end
 
@@ -64,6 +64,6 @@ describe "Delegator#method" do
     @delegate.__setobj__([1,2,3])
     -> {
       m.call
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/methods_spec.rb b/spec/ruby/library/delegate/delegator/methods_spec.rb
index b9942bd230..928f63f21d 100644
--- a/spec/ruby/library/delegate/delegator/methods_spec.rb
+++ b/spec/ruby/library/delegate/delegator/methods_spec.rb
@@ -14,24 +14,24 @@ describe "Delegator#methods" do
   end
 
   it "returns singleton methods when passed false" do
-    @delegate.methods(false).should include(:singleton_method)
+    @delegate.methods(false).should.include?(:singleton_method)
   end
 
   it "includes all public methods of the delegate object" do
-    @methods.should include :pub
+    @methods.should.include? :pub
   end
 
   it "includes all protected methods of the delegate object" do
-    @methods.should include :prot
+    @methods.should.include? :prot
   end
 
   it "includes instance methods of the Delegator class" do
-    @methods.should include :extra
-    @methods.should include :extra_protected
+    @methods.should.include? :extra
+    @methods.should.include? :extra_protected
   end
 
   it "does not include private methods" do
-    @methods.should_not include :priv
-    @methods.should_not include :extra_private
+    @methods.should_not.include? :priv
+    @methods.should_not.include? :extra_private
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/not_equal_spec.rb b/spec/ruby/library/delegate/delegator/not_equal_spec.rb
index 6f2df21715..7fd234a671 100644
--- a/spec/ruby/library/delegate/delegator/not_equal_spec.rb
+++ b/spec/ruby/library/delegate/delegator/not_equal_spec.rb
@@ -9,16 +9,16 @@ describe "Delegator#!=" do
 
   it "is not delegated when passed self" do
     @base.should_not_receive(:"!=")
-    (@delegator != @delegator).should be_false
+    (@delegator != @delegator).should == false
   end
 
   it "is delegated when passed the delegated object" do
     @base.should_receive(:"!=").and_return(true)
-    (@delegator != @base).should be_true
+    (@delegator != @base).should == true
   end
 
   it "is delegated in general" do
     @base.should_receive(:"!=").and_return(false)
-    (@delegator != 42).should be_false
+    (@delegator != 42).should == false
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/private_methods_spec.rb b/spec/ruby/library/delegate/delegator/private_methods_spec.rb
index 7724b8d413..5615ed0668 100644
--- a/spec/ruby/library/delegate/delegator/private_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegator/private_methods_spec.rb
@@ -9,12 +9,12 @@ describe "Delegator#private_methods" do
   end
 
   it "does not include any method of the delegate object" do # since delegates does not forward private calls
-    @methods.should_not include :priv
-    @methods.should_not include :prot
-    @methods.should_not include :pub
+    @methods.should_not.include? :priv
+    @methods.should_not.include? :prot
+    @methods.should_not.include? :pub
   end
 
   it "includes all private instance methods of the Delegate class" do
-    @methods.should include :extra_private
+    @methods.should.include? :extra_private
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/protected_methods_spec.rb b/spec/ruby/library/delegate/delegator/protected_methods_spec.rb
index fd7874fb21..3ee999fdac 100644
--- a/spec/ruby/library/delegate/delegator/protected_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegator/protected_methods_spec.rb
@@ -9,10 +9,10 @@ describe "Delegator#protected_methods" do
   end
 
   it "includes protected methods of the delegate object" do
-    @methods.should include :prot
+    @methods.should.include? :prot
   end
 
   it "includes protected instance methods of the Delegator class" do
-    @methods.should include :extra_protected
+    @methods.should.include? :extra_protected
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/public_methods_spec.rb b/spec/ruby/library/delegate/delegator/public_methods_spec.rb
index 18da16a613..8cf6621e2d 100644
--- a/spec/ruby/library/delegate/delegator/public_methods_spec.rb
+++ b/spec/ruby/library/delegate/delegator/public_methods_spec.rb
@@ -9,10 +9,10 @@ describe "Delegator#public_methods" do
   end
 
   it "includes public methods of the delegate object" do
-    @methods.should include :pub
+    @methods.should.include? :pub
   end
 
   it "includes public instance methods of the Delegator class" do
-    @methods.should include :extra
+    @methods.should.include? :extra
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/send_spec.rb b/spec/ruby/library/delegate/delegator/send_spec.rb
index 3022c2ce91..cc18a2794b 100644
--- a/spec/ruby/library/delegate/delegator/send_spec.rb
+++ b/spec/ruby/library/delegate/delegator/send_spec.rb
@@ -12,15 +12,15 @@ describe "SimpleDelegator.new" do
   end
 
   it "forwards protected method calls" do
-    ->{ @delegate.prot }.should raise_error( NoMethodError )
+    ->{ @delegate.prot }.should.raise( NoMethodError )
   end
 
   it "doesn't forward private method calls" do
-    ->{ @delegate.priv }.should raise_error( NoMethodError )
+    ->{ @delegate.priv }.should.raise( NoMethodError )
   end
 
   it "doesn't forward private method calls even via send or __send__" do
-    ->{ @delegate.send(:priv, 42)     }.should raise_error( NoMethodError )
-    ->{ @delegate.__send__(:priv, 42) }.should raise_error( NoMethodError )
+    ->{ @delegate.send(:priv, 42)     }.should.raise( NoMethodError )
+    ->{ @delegate.__send__(:priv, 42) }.should.raise( NoMethodError )
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/taint_spec.rb b/spec/ruby/library/delegate/delegator/taint_spec.rb
index 2dd0493b53..6bf13bb73d 100644
--- a/spec/ruby/library/delegate/delegator/taint_spec.rb
+++ b/spec/ruby/library/delegate/delegator/taint_spec.rb
@@ -5,19 +5,4 @@ describe "Delegator#taint" do
   before :each do
     @delegate = DelegateSpecs::Delegator.new("")
   end
-
-  it "returns self" do
-    @delegate.taint.equal?(@delegate).should be_true
-  end
-
-  it "taints the delegator" do
-    @delegate.__setobj__(nil)
-    @delegate.taint
-    @delegate.tainted?.should be_true
-  end
-
-  it "taints the delegated object" do
-    @delegate.taint
-    @delegate.__getobj__.tainted?.should be_true
-  end
 end
diff --git a/spec/ruby/library/delegate/delegator/tap_spec.rb b/spec/ruby/library/delegate/delegator/tap_spec.rb
index 34a88fa1d5..916e4a37fe 100644
--- a/spec/ruby/library/delegate/delegator/tap_spec.rb
+++ b/spec/ruby/library/delegate/delegator/tap_spec.rb
@@ -11,6 +11,6 @@ describe "Delegator#tap" do
       yielded << x
     end
     yielded.size.should == 1
-    yielded[0].equal?(delegator).should be_true
+    yielded[0].equal?(delegator).should == true
   end
 end
diff --git a/spec/ruby/library/delegate/delegator/trust_spec.rb b/spec/ruby/library/delegate/delegator/trust_spec.rb
index ba57b3ea18..f1b81814c5 100644
--- a/spec/ruby/library/delegate/delegator/trust_spec.rb
+++ b/spec/ruby/library/delegate/delegator/trust_spec.rb
@@ -5,18 +5,4 @@ describe "Delegator#trust" do
   before :each do
     @delegate = DelegateSpecs::Delegator.new([])
   end
-
-  it "returns self" do
-    @delegate.trust.equal?(@delegate).should be_true
-  end
-
-  it "trusts the delegator" do
-    @delegate.trust
-    @delegate.untrusted?.should be_false
-  end
-
-  it "trusts the delegated object" do
-    @delegate.trust
-    @delegate.__getobj__.untrusted?.should be_false
-  end
 end
diff --git a/spec/ruby/library/delegate/delegator/untaint_spec.rb b/spec/ruby/library/delegate/delegator/untaint_spec.rb
index ddcf854a43..4051fd2629 100644
--- a/spec/ruby/library/delegate/delegator/untaint_spec.rb
+++ b/spec/ruby/library/delegate/delegator/untaint_spec.rb
@@ -5,20 +5,4 @@ describe "Delegator#untaint" do
   before :each do
     @delegate = -> { DelegateSpecs::Delegator.new("") }.call
   end
-
-  it "returns self" do
-    @delegate.untaint.equal?(@delegate).should be_true
-  end
-
-  it "untaints the delegator" do
-    @delegate.untaint
-    @delegate.tainted?.should be_false
-    # No additional meaningful test; that it does or not taint
-    # "for real" the delegator has no consequence
-  end
-
-  it "untaints the delegated object" do
-    @delegate.untaint
-    @delegate.__getobj__.tainted?.should be_false
-  end
 end
diff --git a/spec/ruby/library/delegate/delegator/untrust_spec.rb b/spec/ruby/library/delegate/delegator/untrust_spec.rb
index b7f4bc823e..4f7fa1e582 100644
--- a/spec/ruby/library/delegate/delegator/untrust_spec.rb
+++ b/spec/ruby/library/delegate/delegator/untrust_spec.rb
@@ -5,19 +5,4 @@ describe "Delegator#untrust" do
   before :each do
     @delegate = DelegateSpecs::Delegator.new("")
   end
-
-  it "returns self" do
-    @delegate.untrust.equal?(@delegate).should be_true
-  end
-
-  it "untrusts the delegator" do
-    @delegate.__setobj__(nil)
-    @delegate.untrust
-    @delegate.untrusted?.should be_true
-  end
-
-  it "untrusts the delegated object" do
-    @delegate.untrust
-    @delegate.__getobj__.untrusted?.should be_true
-  end
 end
diff --git a/spec/ruby/library/digest/bubblebabble_spec.rb b/spec/ruby/library/digest/bubblebabble_spec.rb
index e651671108..44a9bf0e26 100644
--- a/spec/ruby/library/digest/bubblebabble_spec.rb
+++ b/spec/ruby/library/digest/bubblebabble_spec.rb
@@ -3,7 +3,7 @@ require 'digest/bubblebabble'
 
 describe "Digest.bubblebabble" do
   it "returns a String" do
-    Digest.bubblebabble('').should be_an_instance_of(String)
+    Digest.bubblebabble('').should.instance_of?(String)
   end
 
   it "returns a String in the Bubble Babble Binary Data Encoding format" do
@@ -20,10 +20,10 @@ describe "Digest.bubblebabble" do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest.bubblebabble(nil) }.should raise_error(TypeError)
+    -> { Digest.bubblebabble(nil) }.should.raise(TypeError)
   end
 
-  it "raises a TypeError when passed a Fixnum" do
-    -> { Digest.bubblebabble(9001) }.should raise_error(TypeError)
+  it "raises a TypeError when passed an Integer" do
+    -> { Digest.bubblebabble(9001) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/hexencode_spec.rb b/spec/ruby/library/digest/hexencode_spec.rb
index fcbbf4846a..3359303d15 100644
--- a/spec/ruby/library/digest/hexencode_spec.rb
+++ b/spec/ruby/library/digest/hexencode_spec.rb
@@ -22,10 +22,10 @@ describe "Digest.hexencode" do
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest.hexencode(nil) }.should raise_error(TypeError)
+    -> { Digest.hexencode(nil) }.should.raise(TypeError)
   end
 
-  it "raises a TypeError when passed a Fixnum" do
-    -> { Digest.hexencode(9001) }.should raise_error(TypeError)
+  it "raises a TypeError when passed an Integer" do
+    -> { Digest.hexencode(9001) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/instance/append_spec.rb b/spec/ruby/library/digest/instance/append_spec.rb
new file mode 100644
index 0000000000..2499579298
--- /dev/null
+++ b/spec/ruby/library/digest/instance/append_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'digest'
+require_relative 'shared/update'
+
+describe "Digest::Instance#<<" do
+  it_behaves_like :digest_instance_update, :<<
+end
diff --git a/spec/ruby/library/digest/instance/new_spec.rb b/spec/ruby/library/digest/instance/new_spec.rb
new file mode 100644
index 0000000000..3f7939844b
--- /dev/null
+++ b/spec/ruby/library/digest/instance/new_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../../spec_helper'
+require 'digest'
+require_relative '../md5/shared/constants'
+
+describe "Digest::Instance#new" do
+  it "returns a copy of the digest instance" do
+    digest = Digest::MD5.new
+    copy = digest.new
+    copy.should_not.equal?(digest)
+  end
+
+  it "calls reset" do
+    digest = Digest::MD5.new
+    digest << "test"
+    digest.hexdigest.should != MD5Constants::BlankHexdigest
+    copy = digest.new
+    copy.hexdigest.should == MD5Constants::BlankHexdigest
+  end
+end
diff --git a/spec/ruby/library/digest/instance/shared/update.rb b/spec/ruby/library/digest/instance/shared/update.rb
new file mode 100644
index 0000000000..e064a90087
--- /dev/null
+++ b/spec/ruby/library/digest/instance/shared/update.rb
@@ -0,0 +1,8 @@
+describe :digest_instance_update, shared: true do
+  it "raises a RuntimeError if called" do
+    c = Class.new do
+      include Digest::Instance
+    end
+    -> { c.new.send(@method, "test") }.should.raise(RuntimeError)
+  end
+end
diff --git a/spec/ruby/library/digest/instance/update_spec.rb b/spec/ruby/library/digest/instance/update_spec.rb
new file mode 100644
index 0000000000..3bb4dd7f1b
--- /dev/null
+++ b/spec/ruby/library/digest/instance/update_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'digest'
+require_relative 'shared/update'
+
+describe "Digest::Instance#update" do
+  it_behaves_like :digest_instance_update, :update
+end
diff --git a/spec/ruby/library/digest/md5/append_spec.rb b/spec/ruby/library/digest/md5/append_spec.rb
index a7f841c883..0abdc074a1 100644
--- a/spec/ruby/library/digest/md5/append_spec.rb
+++ b/spec/ruby/library/digest/md5/append_spec.rb
@@ -3,5 +3,5 @@ require_relative 'shared/constants'
 require_relative 'shared/update'
 
 describe "Digest::MD5#<<" do
- it_behaves_like :md5_update, :<<
+  it_behaves_like :md5_update, :<<
 end
diff --git a/spec/ruby/library/digest/md5/file_spec.rb b/spec/ruby/library/digest/md5/file_spec.rb
index 0c8d12cbc9..9a78a8c055 100644
--- a/spec/ruby/library/digest/md5/file_spec.rb
+++ b/spec/ruby/library/digest/md5/file_spec.rb
@@ -15,7 +15,7 @@ describe "Digest::MD5.file" do
     end
 
     it "returns a Digest::MD5 object" do
-      Digest::MD5.file(@file).should be_kind_of(Digest::MD5)
+      Digest::MD5.file(@file).should.is_a?(Digest::MD5)
     end
 
     it "returns a Digest::MD5 object with the correct digest" do
@@ -26,7 +26,7 @@ describe "Digest::MD5.file" do
       obj = mock("to_str")
       obj.should_receive(:to_str).and_return(@file)
       result = Digest::MD5.file(obj)
-      result.should be_kind_of(Digest::MD5)
+      result.should.is_a?(Digest::MD5)
       result.digest.should == MD5Constants::Digest
     end
   end
@@ -34,10 +34,10 @@ describe "Digest::MD5.file" do
   it_behaves_like :file_read_directory, :file, Digest::MD5
 
   it "raises a Errno::ENOENT when passed a path that does not exist" do
-    -> { Digest::MD5.file("") }.should raise_error(Errno::ENOENT)
+    -> { Digest::MD5.file("") }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest::MD5.file(nil) }.should raise_error(TypeError)
+    -> { Digest::MD5.file(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/md5/shared/constants.rb b/spec/ruby/library/digest/md5/shared/constants.rb
index fdfae56d63..664dd18e9c 100644
--- a/spec/ruby/library/digest/md5/shared/constants.rb
+++ b/spec/ruby/library/digest/md5/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require 'digest/md5'
 
 module MD5Constants
@@ -12,5 +12,6 @@ module MD5Constants
   Digest         = "\2473\267qw\276\364\343\345\320\304\350\313\314\217n"
   BlankHexdigest = "d41d8cd98f00b204e9800998ecf8427e"
   Hexdigest      = "a733b77177bef4e3e5d0c4e8cbcc8f6e"
+  Base64digest   = "pzO3cXe+9OPl0MToy8yPbg=="
 
 end
diff --git a/spec/ruby/library/digest/md5/shared/sample.rb b/spec/ruby/library/digest/md5/shared/sample.rb
deleted file mode 100644
index 2bb4f658b1..0000000000
--- a/spec/ruby/library/digest/md5/shared/sample.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# -*- encoding: binary -*-
-
-require 'digest/md5'
-
-module MD5Constants
-
-  Contents = "Ipsum is simply dummy text of the printing and typesetting industry. \nLorem Ipsum has been the industrys standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. \nIt has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. \nIt was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum."
-
-  Klass          = ::Digest::MD5
-  BlockLength    = 64
-  DigestLength   = 16
-  BlankDigest    = "\324\035\214\331\217\000\262\004\351\200\t\230\354\370B~"
-  Digest         = "\2473\267qw\276\364\343\345\320\304\350\313\314\217n"
-  BlankHexdigest = "d41d8cd98f00b204e9800998ecf8427e"
-  Hexdigest      = "a733b77177bef4e3e5d0c4e8cbcc8f6e"
-
-end
diff --git a/spec/ruby/library/digest/sha1/file_spec.rb b/spec/ruby/library/digest/sha1/file_spec.rb
index 9c15f5b02f..d36e560e21 100644
--- a/spec/ruby/library/digest/sha1/file_spec.rb
+++ b/spec/ruby/library/digest/sha1/file_spec.rb
@@ -15,7 +15,7 @@ describe "Digest::SHA1.file" do
     end
 
     it "returns a Digest::SHA1 object" do
-      Digest::SHA1.file(@file).should be_kind_of(Digest::SHA1)
+      Digest::SHA1.file(@file).should.is_a?(Digest::SHA1)
     end
 
     it "returns a Digest::SHA1 object with the correct digest" do
@@ -26,7 +26,7 @@ describe "Digest::SHA1.file" do
       obj = mock("to_str")
       obj.should_receive(:to_str).and_return(@file)
       result = Digest::SHA1.file(obj)
-      result.should be_kind_of(Digest::SHA1)
+      result.should.is_a?(Digest::SHA1)
       result.digest.should == SHA1Constants::Digest
     end
   end
@@ -34,10 +34,10 @@ describe "Digest::SHA1.file" do
   it_behaves_like :file_read_directory, :file, Digest::SHA1
 
   it "raises a Errno::ENOENT when passed a path that does not exist" do
-    -> { Digest::SHA1.file("") }.should raise_error(Errno::ENOENT)
+    -> { Digest::SHA1.file("") }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest::SHA1.file(nil) }.should raise_error(TypeError)
+    -> { Digest::SHA1.file(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/sha1/shared/constants.rb b/spec/ruby/library/digest/sha1/shared/constants.rb
index add86b1dd3..d77c05a968 100644
--- a/spec/ruby/library/digest/sha1/shared/constants.rb
+++ b/spec/ruby/library/digest/sha1/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require 'digest/sha1'
 
@@ -12,6 +12,7 @@ module SHA1Constants
   BlankDigest    = "\3329\243\356^kK\r2U\277\357\225`\030\220\257\330\a\t"
   Digest         = "X!\255b\323\035\352\314a|q\344+\376\317\361V9\324\343"
   BlankHexdigest = "da39a3ee5e6b4b0d3255bfef95601890afd80709"
-  Hexdigest      = "e907d2ba21c6c74bc0efd76e44d11fb9bbb7a75e"
+  Hexdigest      = "5821ad62d31deacc617c71e42bfecff15639d4e3"
+  Base64digest   = "WCGtYtMd6sxhfHHkK/7P8VY51OM="
 
 end
diff --git a/spec/ruby/library/digest/sha2/hexdigest_spec.rb b/spec/ruby/library/digest/sha2/hexdigest_spec.rb
new file mode 100644
index 0000000000..79beca5788
--- /dev/null
+++ b/spec/ruby/library/digest/sha2/hexdigest_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../../spec_helper'
+require_relative '../sha256/shared/constants'
+
+describe "Digest::SHA2#hexdigest" do
+
+  it "returns a SHA256 hexdigest by default" do
+    cur_digest = Digest::SHA2.new
+    cur_digest.hexdigest.should == SHA256Constants::BlankHexdigest
+
+    # add something to check that the state is reset later
+    cur_digest << "test"
+
+    cur_digest.hexdigest(SHA256Constants::Contents).should == SHA256Constants::Hexdigest
+    # second invocation is intentional, to make sure there are no side-effects
+    cur_digest.hexdigest(SHA256Constants::Contents).should == SHA256Constants::Hexdigest
+
+    # after all is done, verify that the digest is in the original, blank state
+    cur_digest.hexdigest.should == SHA256Constants::BlankHexdigest
+  end
+
+end
+
+describe "Digest::SHA2.hexdigest" do
+
+  it "returns a SHA256 hexdigest by default" do
+    Digest::SHA2.hexdigest(SHA256Constants::Contents).should == SHA256Constants::Hexdigest
+    # second invocation is intentional, to make sure there are no side-effects
+    Digest::SHA2.hexdigest(SHA256Constants::Contents).should == SHA256Constants::Hexdigest
+    Digest::SHA2.hexdigest("").should == SHA256Constants::BlankHexdigest
+  end
+
+end
diff --git a/spec/ruby/library/digest/sha256/append_spec.rb b/spec/ruby/library/digest/sha256/append_spec.rb
index 9ca3496afc..ab594c105f 100644
--- a/spec/ruby/library/digest/sha256/append_spec.rb
+++ b/spec/ruby/library/digest/sha256/append_spec.rb
@@ -3,5 +3,5 @@ require_relative 'shared/constants'
 require_relative 'shared/update'
 
 describe "Digest::SHA256#<<" do
- it_behaves_like :sha256_update, :<<
+  it_behaves_like :sha256_update, :<<
 end
diff --git a/spec/ruby/library/digest/sha256/file_spec.rb b/spec/ruby/library/digest/sha256/file_spec.rb
index 6103971b5a..d67a9ebcd6 100644
--- a/spec/ruby/library/digest/sha256/file_spec.rb
+++ b/spec/ruby/library/digest/sha256/file_spec.rb
@@ -15,18 +15,22 @@ describe "Digest::SHA256.file" do
     end
 
     it "returns a Digest::SHA256 object" do
-      Digest::SHA256.file(@file).should be_kind_of(Digest::SHA256)
+      Digest::SHA256.file(@file).should.is_a?(Digest::SHA256)
     end
 
     it "returns a Digest::SHA256 object with the correct digest" do
       Digest::SHA256.file(@file).digest.should == SHA256Constants::Digest
     end
 
+    it "can be used with frozen-string-literal" do
+      ruby_exe("require 'digest'; puts Digest::SHA256.file(#{@file.inspect}).digest.inspect", options: "--enable=frozen-string-literal").chomp.should == SHA256Constants::Digest.inspect
+    end
+
     it "calls #to_str on an object and returns the Digest::SHA256 with the result" do
       obj = mock("to_str")
       obj.should_receive(:to_str).and_return(@file)
       result = Digest::SHA256.file(obj)
-      result.should be_kind_of(Digest::SHA256)
+      result.should.is_a?(Digest::SHA256)
       result.digest.should == SHA256Constants::Digest
     end
   end
@@ -34,10 +38,10 @@ describe "Digest::SHA256.file" do
   it_behaves_like :file_read_directory, :file, Digest::SHA256
 
   it "raises a Errno::ENOENT when passed a path that does not exist" do
-    -> { Digest::SHA256.file("") }.should raise_error(Errno::ENOENT)
+    -> { Digest::SHA256.file("") }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest::SHA256.file(nil) }.should raise_error(TypeError)
+    -> { Digest::SHA256.file(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/sha256/shared/constants.rb b/spec/ruby/library/digest/sha256/shared/constants.rb
index dd5b48dca9..afe8f11426 100644
--- a/spec/ruby/library/digest/sha256/shared/constants.rb
+++ b/spec/ruby/library/digest/sha256/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require 'digest/sha2'
 
@@ -13,5 +13,6 @@ module SHA256Constants
   Digest         = "\230b\265\344_\337\357\337\242\004\314\311A\211jb\350\373\254\370\365M\230B\002\372\020j\as\270\376"
   BlankHexdigest = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
   Hexdigest      = "9862b5e45fdfefdfa204ccc941896a62e8fbacf8f54d984202fa106a0773b8fe"
+  Base64digest   = "mGK15F/f79+iBMzJQYlqYuj7rPj1TZhCAvoQagdzuP4="
 
 end
diff --git a/spec/ruby/library/digest/sha384/append_spec.rb b/spec/ruby/library/digest/sha384/append_spec.rb
index 2bc0c5b90b..94c036cc3f 100644
--- a/spec/ruby/library/digest/sha384/append_spec.rb
+++ b/spec/ruby/library/digest/sha384/append_spec.rb
@@ -3,5 +3,5 @@ require_relative 'shared/constants'
 require_relative 'shared/update'
 
 describe "Digest::SHA384#<<" do
- it_behaves_like :sha384_update, :<<
+  it_behaves_like :sha384_update, :<<
 end
diff --git a/spec/ruby/library/digest/sha384/file_spec.rb b/spec/ruby/library/digest/sha384/file_spec.rb
index 8556f10175..3726ad4423 100644
--- a/spec/ruby/library/digest/sha384/file_spec.rb
+++ b/spec/ruby/library/digest/sha384/file_spec.rb
@@ -15,7 +15,7 @@ describe "Digest::SHA384.file" do
     end
 
     it "returns a Digest::SHA384 object" do
-      Digest::SHA384.file(@file).should be_kind_of(Digest::SHA384)
+      Digest::SHA384.file(@file).should.is_a?(Digest::SHA384)
     end
 
     it "returns a Digest::SHA384 object with the correct digest" do
@@ -26,7 +26,7 @@ describe "Digest::SHA384.file" do
       obj = mock("to_str")
       obj.should_receive(:to_str).and_return(@file)
       result = Digest::SHA384.file(obj)
-      result.should be_kind_of(Digest::SHA384)
+      result.should.is_a?(Digest::SHA384)
       result.digest.should == SHA384Constants::Digest
     end
   end
@@ -34,10 +34,10 @@ describe "Digest::SHA384.file" do
   it_behaves_like :file_read_directory, :file, Digest::SHA384
 
   it "raises a Errno::ENOENT when passed a path that does not exist" do
-    -> { Digest::SHA384.file("") }.should raise_error(Errno::ENOENT)
+    -> { Digest::SHA384.file("") }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest::SHA384.file(nil) }.should raise_error(TypeError)
+    -> { Digest::SHA384.file(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/sha384/shared/constants.rb b/spec/ruby/library/digest/sha384/shared/constants.rb
index 3697384fc3..a78d571d26 100644
--- a/spec/ruby/library/digest/sha384/shared/constants.rb
+++ b/spec/ruby/library/digest/sha384/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require 'digest/sha2'
 
@@ -14,5 +14,6 @@ module SHA384Constants
   Digest         = "B&\266:\314\216z\361!TD\001{`\355\323\320MW%\270\272\0034n\034\026g\a\217\"\333s\202\275\002Y*\217]\207u\f\034\244\231\266f"
   BlankHexdigest = "38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b"
   Hexdigest      = "4226b63acc8e7af1215444017b60edd3d04d5725b8ba03346e1c1667078f22db7382bd02592a8f5d87750c1ca499b666"
+  Base64digest   = "Qia2OsyOevEhVEQBe2Dt09BNVyW4ugM0bhwWZwePIttzgr0CWSqPXYd1DBykmbZm"
 
 end
diff --git a/spec/ruby/library/digest/sha512/append_spec.rb b/spec/ruby/library/digest/sha512/append_spec.rb
index e5f84b56f4..9106e9685d 100644
--- a/spec/ruby/library/digest/sha512/append_spec.rb
+++ b/spec/ruby/library/digest/sha512/append_spec.rb
@@ -3,5 +3,5 @@ require_relative 'shared/constants'
 require_relative 'shared/update'
 
 describe "Digest::SHA512#<<" do
- it_behaves_like :sha512_update, :<<
+  it_behaves_like :sha512_update, :<<
 end
diff --git a/spec/ruby/library/digest/sha512/file_spec.rb b/spec/ruby/library/digest/sha512/file_spec.rb
index 781ec781e5..78d6d3d4f3 100644
--- a/spec/ruby/library/digest/sha512/file_spec.rb
+++ b/spec/ruby/library/digest/sha512/file_spec.rb
@@ -15,7 +15,7 @@ describe "Digest::SHA512.file" do
     end
 
     it "returns a Digest::SHA512 object" do
-      Digest::SHA512.file(@file).should be_kind_of(Digest::SHA512)
+      Digest::SHA512.file(@file).should.is_a?(Digest::SHA512)
     end
 
     it "returns a Digest::SHA512 object with the correct digest" do
@@ -26,7 +26,7 @@ describe "Digest::SHA512.file" do
       obj = mock("to_str")
       obj.should_receive(:to_str).and_return(@file)
       result = Digest::SHA512.file(obj)
-      result.should be_kind_of(Digest::SHA512)
+      result.should.is_a?(Digest::SHA512)
       result.digest.should == SHA512Constants::Digest
     end
   end
@@ -34,10 +34,10 @@ describe "Digest::SHA512.file" do
   it_behaves_like :file_read_directory, :file, Digest::SHA512
 
   it "raises a Errno::ENOENT when passed a path that does not exist" do
-    -> { Digest::SHA512.file("") }.should raise_error(Errno::ENOENT)
+    -> { Digest::SHA512.file("") }.should.raise(Errno::ENOENT)
   end
 
   it "raises a TypeError when passed nil" do
-    -> { Digest::SHA512.file(nil) }.should raise_error(TypeError)
+    -> { Digest::SHA512.file(nil) }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/digest/sha512/shared/constants.rb b/spec/ruby/library/digest/sha512/shared/constants.rb
index 80f5b7bc1d..91787381ee 100644
--- a/spec/ruby/library/digest/sha512/shared/constants.rb
+++ b/spec/ruby/library/digest/sha512/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 
 require 'digest/sha2'
 
@@ -13,5 +13,6 @@ module SHA512Constants
   Digest         = "\241\231\232\365\002z\241\331\242\310=\367F\272\004\326\331g\315n\251Q\222\250\374E\257\254=\325\225\003SM\350\244\234\220\233=\031\230A;\000\203\233\340\323t\333\271\222w\266\307\2678\344\255j\003\216\300"
   BlankHexdigest = "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e"
   Hexdigest      = "a1999af5027aa1d9a2c83df746ba04d6d967cd6ea95192a8fc45afac3dd59503534de8a49c909b3d1998413b00839be0d374dbb99277b6c7b738e4ad6a038ec0"
+  Base64digest   = "oZma9QJ6odmiyD33RroE1tlnzW6pUZKo/EWvrD3VlQNTTeiknJCbPRmYQTsAg5vg03TbuZJ3tse3OOStagOOwA=="
 
 end
diff --git a/spec/ruby/library/drb/start_service_spec.rb b/spec/ruby/library/drb/start_service_spec.rb
index 016c8b2cff..57a8cf6e15 100644
--- a/spec/ruby/library/drb/start_service_spec.rb
+++ b/spec/ruby/library/drb/start_service_spec.rb
@@ -1,28 +1,33 @@
 require_relative '../../spec_helper'
-require_relative 'fixtures/test_server'
-require 'drb'
 
-describe "DRb.start_service" do
-  before :each do
-    @server = DRb.start_service("druby://localhost:0", TestServer.new)
-  end
+# This does not work yet when run in CRuby via make test-spec:
+# Gem::MissingSpecError: Could not find 'ruby2_keywords' (>= 0) among 28 total gem(s)
+guard_not -> { MSpecScript.instance_variable_defined?(:@testing_ruby) } do
+  require_relative 'fixtures/test_server'
+  require 'drb'
 
-  after :each do
-    DRb.stop_service if @server
-  end
+  describe "DRb.start_service" do
+    before :each do
+      @server = DRb.start_service("druby://localhost:0", TestServer.new)
+    end
 
-  it "runs a basic remote call" do
-    DRb.current_server.should == @server
-    obj = DRbObject.new(nil, @server.uri)
-    obj.add(1,2,3).should == 6
-  end
+    after :each do
+      DRb.stop_service if @server
+    end
+
+    it "runs a basic remote call" do
+      DRb.current_server.should == @server
+      obj = DRbObject.new(nil, @server.uri)
+      obj.add(1,2,3).should == 6
+    end
 
-  it "runs a basic remote call passing a block" do
-    DRb.current_server.should == @server
-    obj = DRbObject.new(nil, @server.uri)
-    obj.add_yield(2) do |i|
-      i.should == 2
-      i+1
-    end.should == 4
+    it "runs a basic remote call passing a block" do
+      DRb.current_server.should == @server
+      obj = DRbObject.new(nil, @server.uri)
+      obj.add_yield(2) do |i|
+        i.should == 2
+        i+1
+      end.should == 4
+    end
   end
 end
diff --git a/spec/ruby/library/erb/def_class_spec.rb b/spec/ruby/library/erb/def_class_spec.rb
index 88bd385f4c..fb687531e0 100644
--- a/spec/ruby/library/erb/def_class_spec.rb
+++ b/spec/ruby/library/erb/def_class_spec.rb
@@ -24,6 +24,8 @@ END
     MyClass1ForErb = erb.def_class(MyClass1ForErb_, 'render()')
     MyClass1ForErb.method_defined?(:render).should == true
     MyClass1ForErb.new('foo', 123).render().should == expected
+  ensure
+    Object.send(:remove_const, :MyClass1ForErb)
   end
 
 end
diff --git a/spec/ruby/library/erb/def_module_spec.rb b/spec/ruby/library/erb/def_module_spec.rb
index 806e564ef0..5f67aeb2b9 100644
--- a/spec/ruby/library/erb/def_module_spec.rb
+++ b/spec/ruby/library/erb/def_module_spec.rb
@@ -22,6 +22,9 @@ END
       include MyModule2ForErb
     end
     MyClass2ForErb.new.render('foo', 123).should == expected
+  ensure
+    Object.send(:remove_const, :MyClass2ForErb)
+    Object.send(:remove_const, :MyModule2ForErb)
   end
 
 end
diff --git a/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb b/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
index dc1e044d9c..1cd7582936 100644
--- a/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
+++ b/spec/ruby/library/erb/defmethod/def_erb_method_spec.rb
@@ -58,6 +58,8 @@ END
       end
     end
     MyClass4ForErb.new([10,20,30]).render().should == expected
+  ensure
+    Object.send(:remove_const, :MY_INPUT4_FOR_ERB)
   end
 
 
diff --git a/spec/ruby/library/erb/filename_spec.rb b/spec/ruby/library/erb/filename_spec.rb
index 8ecaed7343..bbd2233bb3 100644
--- a/spec/ruby/library/erb/filename_spec.rb
+++ b/spec/ruby/library/erb/filename_spec.rb
@@ -13,7 +13,7 @@ describe "ERB#filename" do
         @ex = e
         raise e
       end
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
     expected = filename
 
     @ex.message =~ /^(.*?):(\d+): /
@@ -30,7 +30,7 @@ describe "ERB#filename" do
         @ex = e
         raise e
       end
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
     expected = '(erb)'
 
     @ex.message =~ /^(.*?):(\d+): /
diff --git a/spec/ruby/library/erb/fixtures/classes.rb b/spec/ruby/library/erb/fixtures/classes.rb
index 03da889941..e07a6ed68d 100644
--- a/spec/ruby/library/erb/fixtures/classes.rb
+++ b/spec/ruby/library/erb/fixtures/classes.rb
@@ -1,9 +1,5 @@
 module ERBSpecs
   def self.new_erb(input, trim_mode: nil)
-    if ruby_version_is "2.6"
-      ERB.new(input, trim_mode: trim_mode)
-    else
-      ERB.new(input, nil, trim_mode)
-    end
+    ERB.new(input, trim_mode: trim_mode)
   end
 end
diff --git a/spec/ruby/library/erb/new_spec.rb b/spec/ruby/library/erb/new_spec.rb
index 3bb870dd3f..35ac0dfdfe 100644
--- a/spec/ruby/library/erb/new_spec.rb
+++ b/spec/ruby/library/erb/new_spec.rb
@@ -36,12 +36,10 @@ END
     end
   end
 
-  ruby_version_is "2.6" do
-    it "warns invalid trim_mode" do
-      -> do
-        ERBSpecs.new_erb(@eruby_str, trim_mode: '')
-      end.should complain(/Invalid ERB trim mode/)
-    end
+  it "warns invalid trim_mode" do
+    -> do
+      ERBSpecs.new_erb(@eruby_str, trim_mode: '')
+    end.should complain(/Invalid ERB trim mode/)
   end
 
   it "removes '\n' when trim_mode is 1 or '>'" do
@@ -85,7 +83,7 @@ END
 
     -> {
       ERBSpecs.new_erb(input, trim_mode: '-').result
-    }.should raise_error(SyntaxError)
+    }.should.raise(SyntaxError)
   end
 
   it "regards lines starting with '%' as '<% ... %>' when trim_mode is '%'" do
@@ -120,13 +118,8 @@ END
 
   it "changes '_erbout' variable name in the produced source" do
     input = @eruby_str
-    if RUBY_VERSION >= '2.6'
-      match_erbout = ERB.new(input, trim_mode: nil).src
-      match_buf = ERB.new(input, trim_mode: nil, eoutvar: 'buf').src
-    else
-      match_erbout = ERB.new(input, nil, nil).src
-      match_buf = ERB.new(input, nil, nil, 'buf').src
-    end
+    match_erbout = ERB.new(input, trim_mode: nil).src
+    match_buf = ERB.new(input, trim_mode: nil, eoutvar: 'buf').src
     match_erbout.gsub("_erbout", "buf").should == match_buf
   end
 
@@ -137,12 +130,28 @@ END
 <b><%#= item %></b>
 <%# end %>
 END
-  ERBSpecs.new_erb(input).result.should == "\n<b></b>\n\n"
+    ERBSpecs.new_erb(input).result.should == "\n<b></b>\n\n"
     ERBSpecs.new_erb(input, trim_mode: '<>').result.should == "<b></b>\n"
   end
 
   it "forget local variables defined previous one" do
     ERB.new(@eruby_str).result
-    ->{ ERB.new("<%= list %>").result }.should raise_error(NameError)
+    ->{ ERB.new("<%= list %>").result }.should.raise(NameError)
+  end
+
+  version_is ERB.const_get(:VERSION, false), ""..."6.0.0" do
+    describe "warning about arguments" do
+      it "warns when passed safe_level and later arguments" do
+        -> {
+          ERB.new(@eruby_str, nil, '%')
+        }.should complain(/warning: Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments./)
+      end
+
+      it "does not warn when passed arguments as keyword argument" do
+        -> {
+          ERB.new(@eruby_str, trim_mode: '%')
+        }.should_not complain(/warning: Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments./)
+      end
+    end
   end
 end
diff --git a/spec/ruby/library/erb/result_spec.rb b/spec/ruby/library/erb/result_spec.rb
index a29c1ccedb..84333031ec 100644
--- a/spec/ruby/library/erb/result_spec.rb
+++ b/spec/ruby/library/erb/result_spec.rb
@@ -43,7 +43,7 @@ END
     input = "<%=h '<>' %>"
     -> {
       ERB.new(input).result()
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
 
@@ -81,6 +81,6 @@ END
 
     -> {
       myerb2.new.main2()
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/library/erb/run_spec.rb b/spec/ruby/library/erb/run_spec.rb
index 8c07442d8f..d81d534087 100644
--- a/spec/ruby/library/erb/run_spec.rb
+++ b/spec/ruby/library/erb/run_spec.rb
@@ -6,7 +6,7 @@ describe "ERB#run" do
   # lambda { ... }.should output
   def _steal_stdout
     orig = $stdout
-    s = ''
+    s = +''
     def s.write(arg); self << arg.to_s; end
     $stdout = s
     begin
@@ -54,7 +54,7 @@ END
     input = "<%=h '<>' %>"
     -> {
       _steal_stdout { ERB.new(input).run() }
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 
   it "is able to h() or u() if ERB::Util is included" do
@@ -91,6 +91,6 @@ END
 
     -> {
       _steal_stdout { myerb2.new.main2() }
-    }.should raise_error(NameError)
+    }.should.raise(NameError)
   end
 end
diff --git a/spec/ruby/library/erb/util/shared/url_encode.rb b/spec/ruby/library/erb/util/shared/url_encode.rb
index 5ac6215523..34009c4903 100644
--- a/spec/ruby/library/erb/util/shared/url_encode.rb
+++ b/spec/ruby/library/erb/util/shared/url_encode.rb
@@ -6,21 +6,13 @@ describe :erb_util_url_encode, shared: true do
     ERB::Util.__send__(@method, input).should == expected
   end
 
-  ruby_version_is ""..."2.5" do
-    it "escapes tilde" do
-      ERB::Util.__send__(@method, "~").should == "%7E"
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it "does not escape tilde" do
-      ERB::Util.__send__(@method, "~").should == "~"
-    end
+  it "does not escape tilde" do
+    ERB::Util.__send__(@method, "~").should == "~"
   end
 
   it "encode unicode string" do
-    input = "http://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
-    expected = 'http%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
+    input = "https://ja.wikipedia.org/wiki/\343\203\255\343\203\240\343\202\271\343\202\253\343\203\273\343\203\221\343\203\255\343\203\273\343\202\246\343\203\253\343\203\273\343\203\251\343\203\224\343\203\245\343\202\277"
+    expected = 'https%3A%2F%2Fja.wikipedia.org%2Fwiki%2F%E3%83%AD%E3%83%A0%E3%82%B9%E3%82%AB%E3%83%BB%E3%83%91%E3%83%AD%E3%83%BB%E3%82%A6%E3%83%AB%E3%83%BB%E3%83%A9%E3%83%94%E3%83%A5%E3%82%BF'
     ERB::Util.__send__(@method, input).should == expected
   end
 
diff --git a/spec/ruby/library/etc/confstr_spec.rb b/spec/ruby/library/etc/confstr_spec.rb
index 0c922a3a77..786cb16407 100644
--- a/spec/ruby/library/etc/confstr_spec.rb
+++ b/spec/ruby/library/etc/confstr_spec.rb
@@ -1,14 +1,14 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 require 'etc'
 
-platform_is_not :windows do
+platform_is_not :windows, :android do
   describe "Etc.confstr" do
     it "returns a String for Etc::CS_PATH" do
-      Etc.confstr(Etc::CS_PATH).should be_an_instance_of(String)
+      Etc.confstr(Etc::CS_PATH).should.instance_of?(String)
     end
 
     it "raises Errno::EINVAL for unknown configuration variables" do
-      -> { Etc.confstr(-1) }.should raise_error(Errno::EINVAL)
+      -> { Etc.confstr(-1) }.should.raise(Errno::EINVAL)
     end
   end
 end
diff --git a/spec/ruby/library/etc/getgrgid_spec.rb b/spec/ruby/library/etc/getgrgid_spec.rb
index c7bd55b20e..472d4c82c8 100644
--- a/spec/ruby/library/etc/getgrgid_spec.rb
+++ b/spec/ruby/library/etc/getgrgid_spec.rb
@@ -34,7 +34,7 @@ platform_is_not :windows do
 
       it "returns the Etc::Group for a given gid if it exists" do
         grp = Etc.getgrgid(@gid)
-        grp.should be_kind_of(Etc::Group)
+        grp.should.is_a?(Etc::Group)
         grp.gid.should == @gid
         grp.name.should == @name
       end
@@ -46,20 +46,13 @@ platform_is_not :windows do
         gr.name.should == @name
       end
 
-      it "returns the Group for a given gid if it exists" do
-        grp = Etc.getgrgid(@gid)
-        grp.should be_kind_of(Struct::Group)
-        grp.gid.should == @gid
-        grp.name.should == @name
-      end
-
       it "raises if the group does not exist" do
-        -> { Etc.getgrgid(9876)}.should raise_error(ArgumentError)
+        -> { Etc.getgrgid(9876)}.should.raise(ArgumentError)
       end
 
       it "raises a TypeError if not passed an Integer" do
-        -> { Etc.getgrgid("foo") }.should raise_error(TypeError)
-        -> { Etc.getgrgid(nil)   }.should raise_error(TypeError)
+        -> { Etc.getgrgid("foo") }.should.raise(TypeError)
+        -> { Etc.getgrgid(nil)   }.should.raise(TypeError)
       end
 
       it "can be called safely by multiple threads" do
diff --git a/spec/ruby/library/etc/getgrnam_spec.rb b/spec/ruby/library/etc/getgrnam_spec.rb
index a7c624efbf..325ea7b297 100644
--- a/spec/ruby/library/etc/getgrnam_spec.rb
+++ b/spec/ruby/library/etc/getgrnam_spec.rb
@@ -11,7 +11,7 @@ platform_is :windows do
   end
 end
 
-platform_is_not :windows do
+platform_is_not :windows, :android do
   describe "Etc.getgrnam" do
     it "returns a Etc::Group struct instance for the given group" do
       gr_name = Etc.getgrent.name
@@ -24,7 +24,7 @@ platform_is_not :windows do
       -> {
         Etc.getgrnam(123)
         Etc.getgrnam(nil)
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/etc/getlogin_spec.rb b/spec/ruby/library/etc/getlogin_spec.rb
index 7a4fd79ae2..2bc598c0af 100644
--- a/spec/ruby/library/etc/getlogin_spec.rb
+++ b/spec/ruby/library/etc/getlogin_spec.rb
@@ -14,7 +14,7 @@ describe "Etc.getlogin" do
         if ENV['TRAVIS'] and platform_is(:darwin)
           # See https://travis-ci.org/ruby/spec/jobs/285967744
           # and https://travis-ci.org/ruby/spec/jobs/285999602
-          Etc.getlogin.should be_an_instance_of(String)
+          Etc.getlogin.should.instance_of?(String)
         else
           # Etc.getlogin returns the same result of logname(2)
           # if it returns non NULL
@@ -28,7 +28,7 @@ describe "Etc.getlogin" do
       else
         # Etc.getlogin may return nil if the login name is not set
         # because of chroot or sudo or something.
-        Etc.getlogin.should be_nil
+        Etc.getlogin.should == nil
         getlogin_null = true
       end
     ensure
diff --git a/spec/ruby/library/etc/getpwnam_spec.rb b/spec/ruby/library/etc/getpwnam_spec.rb
index 3f4416aa9d..a0b3c9e1fe 100644
--- a/spec/ruby/library/etc/getpwnam_spec.rb
+++ b/spec/ruby/library/etc/getpwnam_spec.rb
@@ -22,7 +22,7 @@ platform_is_not :windows do
       -> {
         Etc.getpwnam(123)
         Etc.getpwnam(nil)
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/etc/getpwuid_spec.rb b/spec/ruby/library/etc/getpwuid_spec.rb
index 5b98f0f8d9..3e35dfe6d5 100644
--- a/spec/ruby/library/etc/getpwuid_spec.rb
+++ b/spec/ruby/library/etc/getpwuid_spec.rb
@@ -30,7 +30,7 @@ platform_is_not :windows do
       -> {
         Etc.getpwuid("foo")
         Etc.getpwuid(nil)
-      }.should raise_error(TypeError)
+      }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/etc/group_spec.rb b/spec/ruby/library/etc/group_spec.rb
index fdd39bda16..d7addbbec1 100644
--- a/spec/ruby/library/etc/group_spec.rb
+++ b/spec/ruby/library/etc/group_spec.rb
@@ -5,11 +5,11 @@ require 'etc'
 describe "Etc.group" do
   it_behaves_like :etc_on_windows, :group
 
-  platform_is_not :windows do
+  platform_is_not :windows, :android do
     it "returns a Etc::Group struct" do
       group = Etc.group
       begin
-        group.should be_an_instance_of(Etc::Group)
+        group.should.instance_of?(Etc::Group)
       ensure
         Etc.endgrent
       end
@@ -21,7 +21,7 @@ describe "Etc.group" do
           Etc.group do | group2 |
           end
         end
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
   end
 end
diff --git a/spec/ruby/library/etc/nprocessors_spec.rb b/spec/ruby/library/etc/nprocessors_spec.rb
index ec7ffc81da..482719dde0 100644
--- a/spec/ruby/library/etc/nprocessors_spec.rb
+++ b/spec/ruby/library/etc/nprocessors_spec.rb
@@ -3,7 +3,7 @@ require 'etc'
 
 describe "Etc.nprocessors" do
   it "returns the number of online processors" do
-    Etc.nprocessors.should be_kind_of(Integer)
+    Etc.nprocessors.should.is_a?(Integer)
     Etc.nprocessors.should >= 1
   end
 end
diff --git a/spec/ruby/library/etc/passwd_spec.rb b/spec/ruby/library/etc/passwd_spec.rb
index d61dada451..0602b7e10b 100644
--- a/spec/ruby/library/etc/passwd_spec.rb
+++ b/spec/ruby/library/etc/passwd_spec.rb
@@ -1,4 +1,4 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 require 'etc'
 
 platform_is_not :windows do
@@ -6,7 +6,7 @@ platform_is_not :windows do
     it "returns a Etc::Passwd struct" do
       passwd = Etc.passwd
       begin
-        passwd.should be_an_instance_of(Etc::Passwd)
+        passwd.should.instance_of?(Etc::Passwd)
       ensure
         Etc.endpwent
       end
diff --git a/spec/ruby/library/etc/struct_group_spec.rb b/spec/ruby/library/etc/struct_group_spec.rb
index 0b50ff578f..b2147e306d 100644
--- a/spec/ruby/library/etc/struct_group_spec.rb
+++ b/spec/ruby/library/etc/struct_group_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 require 'etc'
 
-describe "Struct::Group" do
+describe "Etc::Group" do
   platform_is_not :windows do
     grpname = IO.popen(%w'id -gn', err: IO::NULL, &:read)
     next unless $?.success?
diff --git a/spec/ruby/library/etc/struct_passwd_spec.rb b/spec/ruby/library/etc/struct_passwd_spec.rb
index 93ad9dfa2a..dc37c17e7d 100644
--- a/spec/ruby/library/etc/struct_passwd_spec.rb
+++ b/spec/ruby/library/etc/struct_passwd_spec.rb
@@ -1,7 +1,7 @@
 require_relative '../../spec_helper'
 require 'etc'
 
-describe "Struct::Passwd" do
+describe "Etc::Passwd" do
   platform_is_not :windows do
     before :all do
       @pw = Etc.getpwuid(`id -u`.strip.to_i)
diff --git a/spec/ruby/library/etc/sysconf_spec.rb b/spec/ruby/library/etc/sysconf_spec.rb
index e7d59d1b22..81ce1ca258 100644
--- a/spec/ruby/library/etc/sysconf_spec.rb
+++ b/spec/ruby/library/etc/sysconf_spec.rb
@@ -1,4 +1,4 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 require 'etc'
 
 platform_is_not :windows do
@@ -14,7 +14,7 @@ platform_is_not :windows do
         if value.nil?
           value.should == nil
         else
-          value.should be_kind_of(Integer)
+          value.should.is_a?(Integer)
         end
       end
     end
diff --git a/spec/ruby/library/etc/sysconfdir_spec.rb b/spec/ruby/library/etc/sysconfdir_spec.rb
index d54299c513..eb2d6b649a 100644
--- a/spec/ruby/library/etc/sysconfdir_spec.rb
+++ b/spec/ruby/library/etc/sysconfdir_spec.rb
@@ -1,8 +1,8 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 require 'etc'
 
 describe "Etc.sysconfdir" do
   it "returns a String" do
-    Etc.sysconfdir.should be_an_instance_of(String)
+    Etc.sysconfdir.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/library/etc/systmpdir_spec.rb b/spec/ruby/library/etc/systmpdir_spec.rb
index 99c82903f8..ed34cb43fc 100644
--- a/spec/ruby/library/etc/systmpdir_spec.rb
+++ b/spec/ruby/library/etc/systmpdir_spec.rb
@@ -1,8 +1,8 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 require 'etc'
 
 describe "Etc.systmpdir" do
   it "returns a String" do
-    Etc.systmpdir.should be_an_instance_of(String)
+    Etc.systmpdir.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/library/etc/uname_spec.rb b/spec/ruby/library/etc/uname_spec.rb
new file mode 100644
index 0000000000..1c5fe2a741
--- /dev/null
+++ b/spec/ruby/library/etc/uname_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+require 'etc'
+
+describe "Etc.uname" do
+  it "returns a Hash with the documented keys" do
+    uname = Etc.uname
+    uname.should.is_a?(Hash)
+    uname.should.key?(:sysname)
+    uname.should.key?(:nodename)
+    uname.should.key?(:release)
+    uname.should.key?(:version)
+    uname.should.key?(:machine)
+  end
+end
diff --git a/spec/ruby/library/expect/expect_spec.rb b/spec/ruby/library/expect/expect_spec.rb
index a7041d42ee..ba705c5535 100644
--- a/spec/ruby/library/expect/expect_spec.rb
+++ b/spec/ruby/library/expect/expect_spec.rb
@@ -1,5 +1,6 @@
+require_relative '../../spec_helper'
+
 platform_is_not :windows do
-  require_relative '../../spec_helper'
   require 'expect'
 
   describe "IO#expect" do
@@ -39,14 +40,14 @@ platform_is_not :windows do
 
       -> {
         @read.expect("hello")
-      }.should raise_error(IOError)
+      }.should.raise(IOError)
     end
 
     it "returns nil if eof is hit" do
       @write << "pro"
       @write.close
 
-      @read.expect("prompt").should be_nil
+      @read.expect("prompt").should == nil
     end
 
     it "yields the result if a block is given" do
diff --git a/spec/ruby/library/fiber/alive_spec.rb b/spec/ruby/library/fiber/alive_spec.rb
deleted file mode 100644
index 47149d5279..0000000000
--- a/spec/ruby/library/fiber/alive_spec.rb
+++ /dev/null
@@ -1,46 +0,0 @@
-require_relative '../../spec_helper'
-
-require 'fiber'
-
-describe "Fiber#alive?" do
-  it "returns true for a Fiber that hasn't had #resume called" do
-    fiber = Fiber.new { true }
-    fiber.alive?.should be_true
-  end
-
-  # FIXME: Better description?
-  it "returns true for a Fiber that's yielded to the caller" do
-    fiber = Fiber.new { Fiber.yield }
-    fiber.resume
-    fiber.alive?.should be_true
-  end
-
-  it "returns true when called from its Fiber" do
-    fiber = Fiber.new { fiber.alive?.should be_true }
-    fiber.resume
-  end
-
-  it "doesn't invoke the block associated with the Fiber" do
-    offthehook = mock('do not call')
-    offthehook.should_not_receive(:ring)
-    fiber = Fiber.new { offthehook.ring }
-    fiber.alive?
-  end
-
-  it "returns false for a Fiber that's dead" do
-    fiber = Fiber.new { true }
-    fiber.resume
-    -> { fiber.resume }.should raise_error(FiberError)
-    fiber.alive?.should be_false
-  end
-
-  it "always returns false for a dead Fiber" do
-    fiber = Fiber.new { true }
-    fiber.resume
-    -> { fiber.resume }.should raise_error(FiberError)
-    fiber.alive?.should be_false
-    -> { fiber.resume }.should raise_error(FiberError)
-    fiber.alive?.should be_false
-    fiber.alive?.should be_false
-  end
-end
diff --git a/spec/ruby/library/fiber/current_spec.rb b/spec/ruby/library/fiber/current_spec.rb
deleted file mode 100644
index 52dff3dea1..0000000000
--- a/spec/ruby/library/fiber/current_spec.rb
+++ /dev/null
@@ -1,51 +0,0 @@
-require_relative '../../spec_helper'
-
-require 'fiber'
-
-describe "Fiber.current" do
-  it "returns the root Fiber when called outside of a Fiber" do
-    root = Fiber.current
-    root.should be_an_instance_of(Fiber)
-    # We can always transfer to the root Fiber; it will never die
-    5.times do
-      root.transfer.should be_nil
-      root.alive?.should be_true
-    end
-  end
-
-  it "returns the current Fiber when called from a Fiber" do
-    fiber = Fiber.new do
-      this = Fiber.current
-      this.should be_an_instance_of(Fiber)
-      this.should == fiber
-      this.alive?.should be_true
-    end
-    fiber.resume
-  end
-
-  it "returns the current Fiber when called from a Fiber that transferred to another" do
-    states = []
-    fiber = Fiber.new do
-      states << :fiber
-      this = Fiber.current
-      this.should be_an_instance_of(Fiber)
-      this.should == fiber
-      this.alive?.should be_true
-    end
-
-    fiber2 = Fiber.new do
-      states << :fiber2
-      fiber.transfer
-      flunk
-    end
-
-    fiber3 = Fiber.new do
-      states << :fiber3
-      fiber2.transfer
-      flunk
-    end
-
-    fiber3.resume
-    states.should == [:fiber3, :fiber2, :fiber]
-  end
-end
diff --git a/spec/ruby/library/fiber/resume_spec.rb b/spec/ruby/library/fiber/resume_spec.rb
deleted file mode 100644
index dae717c8a1..0000000000
--- a/spec/ruby/library/fiber/resume_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-
-require 'fiber'
-
-describe "Fiber#resume" do
-  it "raises a FiberError if the Fiber has transferred control to another Fiber" do
-    fiber1 = Fiber.new { true }
-    fiber2 = Fiber.new { fiber1.transfer; Fiber.yield }
-    fiber2.resume
-    -> { fiber2.resume }.should raise_error(FiberError)
-  end
-end
diff --git a/spec/ruby/library/fiber/transfer_spec.rb b/spec/ruby/library/fiber/transfer_spec.rb
deleted file mode 100644
index d13053666c..0000000000
--- a/spec/ruby/library/fiber/transfer_spec.rb
+++ /dev/null
@@ -1,86 +0,0 @@
-require_relative '../../spec_helper'
-require_relative '../../shared/fiber/resume'
-
-require 'fiber'
-
-describe "Fiber#transfer" do
-  it_behaves_like :fiber_resume, :transfer
-end
-
-describe "Fiber#transfer" do
-  it "transfers control from one Fiber to another when called from a Fiber" do
-    fiber1 = Fiber.new { :fiber1 }
-    fiber2 = Fiber.new { fiber1.transfer; :fiber2 }
-    fiber2.resume.should == :fiber1
-  end
-
-  it "returns to the root Fiber when finished" do
-    f1 = Fiber.new { :fiber_1 }
-    f2 = Fiber.new { f1.transfer; :fiber_2 }
-
-    f2.transfer.should == :fiber_1
-    f2.transfer.should == :fiber_2
-  end
-
-  it "can be invoked from the same Fiber it transfers control to" do
-    states = []
-    fiber = Fiber.new { states << :start; fiber.transfer; states << :end }
-    fiber.transfer
-    states.should == [:start, :end]
-
-    states = []
-    fiber = Fiber.new { states << :start; fiber.transfer; states << :end }
-    fiber.resume
-    states.should == [:start, :end]
-  end
-
-  it "can transfer control to a Fiber that has transferred to another Fiber" do
-    states = []
-    fiber1 = Fiber.new { states << :fiber1 }
-    fiber2 = Fiber.new { states << :fiber2_start; fiber1.transfer; states << :fiber2_end}
-    fiber2.resume.should == [:fiber2_start, :fiber1]
-    fiber2.transfer.should == [:fiber2_start, :fiber1, :fiber2_end]
-  end
-
-  it "raises a FiberError when transferring to a Fiber which resumes itself" do
-    fiber = Fiber.new { fiber.resume }
-    -> { fiber.transfer }.should raise_error(FiberError)
-  end
-
-  it "works if Fibers in different Threads each transfer to a Fiber in the same Thread" do
-    # This catches a bug where Fibers are running on a thread-pool
-    # and Fibers from a different Ruby Thread reuse the same native thread.
-    # Caching the Ruby Thread based on the native thread is not correct in that case,
-    # and the check for "fiber called across threads" in Fiber#transfer
-    # might be incorrect based on that.
-    2.times do
-      Thread.new do
-        io_fiber = Fiber.new do |calling_fiber|
-          calling_fiber.transfer
-        end
-        io_fiber.transfer(Fiber.current)
-        value = Object.new
-        io_fiber.transfer(value).should equal value
-      end.join
-    end
-  end
-
-  it "transfers control between a non-main thread's root fiber to a child fiber and back again" do
-    states = []
-    thread = Thread.new do
-      f1 = Fiber.new do |f0|
-        states << 0
-        value2 = f0.transfer(1)
-        states << value2
-        3
-      end
-
-      value1 = f1.transfer(Fiber.current)
-      states << value1
-      value3 = f1.transfer(2)
-      states << value3
-    end
-    thread.join
-    states.should == [0, 1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/fiddle/handle/initialize_spec.rb b/spec/ruby/library/fiddle/handle/initialize_spec.rb
new file mode 100644
index 0000000000..84c809a727
--- /dev/null
+++ b/spec/ruby/library/fiddle/handle/initialize_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../../spec_helper'
+require 'fiddle'
+
+describe "Fiddle::Handle#initialize" do
+  it "raises Fiddle::DLError if the library cannot be found" do
+    -> {
+      Fiddle::Handle.new("doesnotexist.doesnotexist")
+    }.should.raise(Fiddle::DLError)
+  end
+end
diff --git a/spec/ruby/library/find/find_spec.rb b/spec/ruby/library/find/find_spec.rb
index 7cd76fa01b..c4ccfa76fd 100644
--- a/spec/ruby/library/find/find_spec.rb
+++ b/spec/ruby/library/find/find_spec.rb
@@ -13,7 +13,7 @@ describe "Find.find" do
 
   describe "when called without a block" do
     it "returns an Enumerator" do
-      Find.find(FindDirSpecs.mock_dir).should be_an_instance_of(Enumerator)
+      Find.find(FindDirSpecs.mock_dir).should.instance_of?(Enumerator)
       Find.find(FindDirSpecs.mock_dir).to_a.sort.should == FindDirSpecs.expected_paths
     end
   end
diff --git a/spec/ruby/library/find/fixtures/common.rb b/spec/ruby/library/find/fixtures/common.rb
index 14a7edb09a..99f3bbb45a 100644
--- a/spec/ruby/library/find/fixtures/common.rb
+++ b/spec/ruby/library/find/fixtures/common.rb
@@ -71,13 +71,17 @@ module FindDirSpecs
   end
 
   def self.create_mock_dirs
+    tmp('') # make sure there is an tmpdir
     umask = File.umask 0
-    mock_dir_files.each do |name|
-      file = File.join mock_dir, name
-      mkdir_p File.dirname(file)
-      touch file
+    begin
+      mock_dir_files.each do |name|
+        file = File.join mock_dir, name
+        mkdir_p File.dirname(file)
+        touch file
+      end
+    ensure
+      File.umask umask
     end
-    File.umask umask
   end
 
   def self.delete_mock_dirs
diff --git a/spec/ruby/library/getoptlong/error_message_spec.rb b/spec/ruby/library/getoptlong/error_message_spec.rb
index 1ed9419f6c..10435b1350 100644
--- a/spec/ruby/library/getoptlong/error_message_spec.rb
+++ b/spec/ruby/library/getoptlong/error_message_spec.rb
@@ -14,7 +14,7 @@ describe "GetoptLong#error_message" do
       opts.get
       -> {
         opts.ordering = GetoptLong::PERMUTE
-      }.should raise_error(ArgumentError) { |e|
+      }.should.raise(ArgumentError) { |e|
         e.message.should == "argument error"
         opts.error_message.should == "argument error"
       }
diff --git a/spec/ruby/library/getoptlong/ordering_spec.rb b/spec/ruby/library/getoptlong/ordering_spec.rb
index 695d1cafa7..60ce73afaa 100644
--- a/spec/ruby/library/getoptlong/ordering_spec.rb
+++ b/spec/ruby/library/getoptlong/ordering_spec.rb
@@ -11,7 +11,7 @@ describe "GetoptLong#ordering=" do
 
       -> {
         opts.ordering = GetoptLong::PERMUTE
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -20,7 +20,7 @@ describe "GetoptLong#ordering=" do
 
     -> {
       opts.ordering = 12345
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "does not allow changing ordering to PERMUTE if ENV['POSIXLY_CORRECT'] is set" do
diff --git a/spec/ruby/library/getoptlong/set_options_spec.rb b/spec/ruby/library/getoptlong/set_options_spec.rb
index 36b9c579c4..f60dcc87a3 100644
--- a/spec/ruby/library/getoptlong/set_options_spec.rb
+++ b/spec/ruby/library/getoptlong/set_options_spec.rb
@@ -41,7 +41,7 @@ describe "GetoptLong#set_options" do
     argv [] do
       -> {
         @opts.set_options(["--size", GetoptLong::NO_ARGUMENT, GetoptLong::REQUIRED_ARGUMENT])
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -50,7 +50,7 @@ describe "GetoptLong#set_options" do
       @opts.get
       -> {
         @opts.set_options()
-      }.should raise_error(RuntimeError)
+      }.should.raise(RuntimeError)
     end
   end
 
@@ -58,7 +58,7 @@ describe "GetoptLong#set_options" do
     argv [] do
       -> {
         @opts.set_options(["--size"])
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -68,7 +68,7 @@ describe "GetoptLong#set_options" do
         @opts.set_options(
           ["--size", GetoptLong::REQUIRED_ARGUMENT],
           "test")
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -78,13 +78,13 @@ describe "GetoptLong#set_options" do
         @opts.set_options(
           ["--size", GetoptLong::NO_ARGUMENT],
           ["--size", GetoptLong::OPTIONAL_ARGUMENT])
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
 
       -> {
         @opts.set_options(
           ["--size", GetoptLong::NO_ARGUMENT],
           ["-s", "--size", GetoptLong::OPTIONAL_ARGUMENT])
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 
@@ -92,7 +92,7 @@ describe "GetoptLong#set_options" do
     argv [] do
       -> {
         @opts.set_options(["-size", GetoptLong::NO_ARGUMENT])
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/library/getoptlong/shared/get.rb b/spec/ruby/library/getoptlong/shared/get.rb
index 772a7f6773..8d24c4c255 100644
--- a/spec/ruby/library/getoptlong/shared/get.rb
+++ b/spec/ruby/library/getoptlong/shared/get.rb
@@ -49,16 +49,14 @@ describe :getoptlong_get, shared: true do
 
   it "raises a if an argument was required, but none given" do
     argv [ "--size" ] do
-      -> { @opts.send(@method) }.should raise_error(GetoptLong::MissingArgument)
+      -> { @opts.send(@method) }.should.raise(GetoptLong::MissingArgument)
     end
   end
 
-  ruby_version_is "2.5" do
-    # https://bugs.ruby-lang.org/issues/13858
-    it "returns multiline argument" do
-      argv [ "--size=\n10k\n" ] do
-        @opts.send(@method).should == [ "--size", "\n10k\n" ]
-      end
+  # https://bugs.ruby-lang.org/issues/13858
+  it "returns multiline argument" do
+    argv [ "--size=\n10k\n" ] do
+      @opts.send(@method).should == [ "--size", "\n10k\n" ]
     end
   end
 end
diff --git a/spec/ruby/library/getoptlong/terminated_spec.rb b/spec/ruby/library/getoptlong/terminated_spec.rb
index 01a8feddea..6108a7f6e9 100644
--- a/spec/ruby/library/getoptlong/terminated_spec.rb
+++ b/spec/ruby/library/getoptlong/terminated_spec.rb
@@ -5,13 +5,13 @@ describe "GetoptLong#terminated?" do
   it "returns true if option processing has terminated" do
     argv [ "--size", "10k" ] do
       opts = GetoptLong.new(["--size", GetoptLong::REQUIRED_ARGUMENT])
-      opts.terminated?.should == false
+      opts.should_not.terminated?
 
       opts.get.should == ["--size", "10k"]
-      opts.terminated?.should == false
+      opts.should_not.terminated?
 
       opts.get.should == nil
-      opts.terminated?.should == true
+      opts.should.terminated?
     end
   end
 end
diff --git a/spec/ruby/library/io-wait/wait_readable_spec.rb b/spec/ruby/library/io-wait/wait_readable_spec.rb
new file mode 100644
index 0000000000..d7473f029f
--- /dev/null
+++ b/spec/ruby/library/io-wait/wait_readable_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+
+describe "IO#wait_readable" do
+  before :each do
+    @io = File.new(__FILE__ )
+  end
+
+  after :each do
+    @io.close
+  end
+
+  it "waits for the IO to become readable with no timeout" do
+    @io.wait_readable.should == @io
+  end
+
+  it "waits for the IO to become readable with the given timeout" do
+    @io.wait_readable(1).should == @io
+  end
+
+  it "waits for the IO to become readable with the given large timeout" do
+    @io.wait_readable(365 * 24 * 60 * 60).should == @io
+  end
+
+  it "can be interrupted" do
+    rd, wr = IO.pipe
+    start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+    t = Thread.new do
+      rd.wait_readable(10)
+    end
+
+    Thread.pass until t.stop?
+    t.kill
+    t.join
+
+    finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    (finish - start).should < 9
+  ensure
+    rd.close
+    wr.close
+  end
+end
diff --git a/spec/ruby/library/io-wait/wait_spec.rb b/spec/ruby/library/io-wait/wait_spec.rb
new file mode 100644
index 0000000000..1d784e7aa4
--- /dev/null
+++ b/spec/ruby/library/io-wait/wait_spec.rb
@@ -0,0 +1,162 @@
+require_relative '../../spec_helper'
+require_relative '../../fixtures/io'
+
+describe "IO#wait" do
+  before :each do
+    @io = File.new(__FILE__ )
+
+    if /mswin|mingw/ =~ RUBY_PLATFORM
+      require 'socket'
+      @r, @w = Socket.pair(Socket::AF_INET, Socket::SOCK_STREAM, 0)
+    else
+      @r, @w = IO.pipe
+    end
+  end
+
+  after :each do
+    @io.close unless @io.closed?
+
+    @r.close unless @r.closed?
+    @w.close unless @w.closed?
+  end
+
+  context "[events, timeout] passed" do
+    it "returns events mask when the READABLE event is ready during the timeout" do
+      @w.write('data to read')
+      @r.wait(IO::READABLE, 2).should == IO::READABLE
+    end
+
+    it "returns events mask when the WRITABLE event is ready during the timeout" do
+      @w.wait(IO::WRITABLE, 0).should == IO::WRITABLE
+    end
+
+    it "waits for the READABLE event to be ready" do
+      @r.wait(IO::READABLE, 0).should == nil
+
+      @w.write('data to read')
+      @r.wait(IO::READABLE, 0).should_not == nil
+    end
+
+    it "waits for the WRITABLE event to be ready" do
+      written_bytes = IOSpec.exhaust_write_buffer(@w)
+      @w.wait(IO::WRITABLE, 0).should == nil
+
+      @r.read(written_bytes)
+      @w.wait(IO::WRITABLE, 0).should_not == nil
+    end
+
+    it "returns nil when the READABLE event is not ready during the timeout" do
+      @w.wait(IO::READABLE, 0).should == nil
+    end
+
+    it "returns nil when the WRITABLE event is not ready during the timeout" do
+      IOSpec.exhaust_write_buffer(@w)
+      @w.wait(IO::WRITABLE, 0).should == nil
+    end
+
+    it "raises IOError when io is closed (closed stream (IOError))" do
+      @io.close
+      -> { @io.wait(IO::READABLE, 0) }.should.raise(IOError, "closed stream")
+    end
+
+    it "raises ArgumentError when events is not positive" do
+      -> { @w.wait(0, 0) }.should.raise(ArgumentError, "Events must be positive integer!")
+      -> { @w.wait(-1, 0) }.should.raise(ArgumentError, "Events must be positive integer!")
+    end
+
+    it "changes thread status to 'sleep' when waits for READABLE event" do
+      t = Thread.new { @r.wait(IO::READABLE, 10) }
+      sleep 1
+      t.status.should == 'sleep'
+      t.kill
+      t.join # Thread#kill doesn't wait for the thread to end
+    end
+
+    # https://github.com/ruby/ruby/actions/runs/11948300522/job/33305664284?pr=12139
+    platform_is_not :windows do
+      it "changes thread status to 'sleep' when waits for WRITABLE event" do
+        IOSpec.exhaust_write_buffer(@w)
+
+        t = Thread.new { @w.wait(IO::WRITABLE, 10) }
+        sleep 1
+        t.status.should == 'sleep'
+        t.kill
+        t.join # Thread#kill doesn't wait for the thread to end
+      end
+    end
+
+    it "can be interrupted when waiting for READABLE event" do
+      start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+      t = Thread.new do
+        @r.wait(IO::READABLE, 10)
+      end
+
+      Thread.pass until t.stop?
+      t.kill
+      t.join # Thread#kill doesn't wait for the thread to end
+
+      finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+      (finish - start).should < 9
+    end
+
+    it "can be interrupted when waiting for WRITABLE event" do
+      IOSpec.exhaust_write_buffer(@w)
+      start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+      t = Thread.new do
+        @w.wait(IO::WRITABLE, 10)
+      end
+
+      Thread.pass until t.stop?
+      t.kill
+      t.join # Thread#kill doesn't wait for the thread to end
+
+      finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+      (finish - start).should < 9
+    end
+  end
+
+  context "[timeout, mode] passed" do
+    it "accepts :r, :read, :readable mode to check READABLE event" do
+      @io.wait(0, :r).should == @io
+      @io.wait(0, :read).should == @io
+      @io.wait(0, :readable).should == @io
+    end
+
+    it "accepts :w, :write, :writable mode to check WRITABLE event" do
+      @io.wait(0, :w).should == @io
+      @io.wait(0, :write).should == @io
+      @io.wait(0, :writable).should == @io
+    end
+
+    it "accepts :rw, :read_write, :readable_writable mode to check READABLE and WRITABLE events" do
+      @io.wait(0, :rw).should == @io
+      @io.wait(0, :read_write).should == @io
+      @io.wait(0, :readable_writable).should == @io
+    end
+
+    it "accepts a list of modes" do
+      @io.wait(0, :r, :w, :rw).should == @io
+    end
+
+    it "accepts timeout and mode in any order" do
+      @io.wait(0, :r).should == @io
+      @io.wait(:r, 0).should == @io
+      @io.wait(:r, 0, :w).should == @io
+    end
+
+    it "raises ArgumentError when passed wrong Symbol value as mode argument" do
+      -> { @io.wait(0, :wrong) }.should.raise(ArgumentError, "unsupported mode: wrong")
+    end
+
+    it "raises ArgumentError when several Integer arguments passed" do
+      -> { @w.wait(0, 10, :r) }.should.raise(ArgumentError, "timeout given more than once")
+    end
+
+    it "raises IOError when io is closed (closed stream (IOError))" do
+      @io.close
+      -> { @io.wait(0, :r) }.should.raise(IOError, "closed stream")
+    end
+  end
+end
diff --git a/spec/ruby/library/io-wait/wait_writable_spec.rb b/spec/ruby/library/io-wait/wait_writable_spec.rb
new file mode 100644
index 0000000000..2017817caa
--- /dev/null
+++ b/spec/ruby/library/io-wait/wait_writable_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+require_relative '../../fixtures/io'
+
+describe "IO#wait_writable" do
+  it "waits for the IO to become writable with no timeout" do
+    STDOUT.wait_writable.should == STDOUT
+  end
+
+  it "waits for the IO to become writable with the given timeout" do
+    STDOUT.wait_writable(1).should == STDOUT
+  end
+
+  it "waits for the IO to become writable with the given large timeout" do
+    # Represents one year and is larger than a 32-bit int
+    STDOUT.wait_writable(365 * 24 * 60 * 60).should == STDOUT
+  end
+
+  it "can be interrupted" do
+    rd, wr = IO.pipe
+    IOSpec.exhaust_write_buffer(wr)
+    start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+    t = Thread.new do
+      wr.wait_writable(10)
+    end
+
+    Thread.pass until t.stop?
+    t.kill
+    t.join
+
+    finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    (finish - start).should < 9
+  ensure
+    rd.close unless rd.closed?
+    wr.close unless wr.closed?
+  end
+end
diff --git a/spec/ruby/library/ipaddr/ipv4_conversion_spec.rb b/spec/ruby/library/ipaddr/ipv4_conversion_spec.rb
index 9d45055d76..1128c16dd2 100644
--- a/spec/ruby/library/ipaddr/ipv4_conversion_spec.rb
+++ b/spec/ruby/library/ipaddr/ipv4_conversion_spec.rb
@@ -8,11 +8,11 @@ describe "IPAddr#ipv4_compat" do
     a.to_s.should == "::192.168.1.2"
     a.to_string.should == "0000:0000:0000:0000:0000:0000:c0a8:0102"
     a.family.should == Socket::AF_INET6
-    a.ipv4_compat?.should == true
+    a.should.ipv4_compat?
     b = a.native
     b.to_s.should == "192.168.1.2"
     b.family.should == Socket::AF_INET
-    b.ipv4_compat?.should == false
+    b.should_not.ipv4_compat?
 
     a = IPAddr.new("192.168.1.2")
     b = a.ipv4_compat
@@ -29,11 +29,11 @@ describe "IPAddr#ipv4_mapped" do
     a.to_s.should == "::ffff:192.168.1.2"
     a.to_string.should == "0000:0000:0000:0000:0000:ffff:c0a8:0102"
     a.family.should == Socket::AF_INET6
-    a.ipv4_mapped?.should == true
+    a.should.ipv4_mapped?
     b = a.native
     b.to_s.should == "192.168.1.2"
     b.family.should == Socket::AF_INET
-    b.ipv4_mapped?.should == false
+    b.should_not.ipv4_mapped?
 
     a = IPAddr.new("192.168.1.2")
     b = a.ipv4_mapped
diff --git a/spec/ruby/library/ipaddr/new_spec.rb b/spec/ruby/library/ipaddr/new_spec.rb
index c8c8bc80b3..7fba2b372e 100644
--- a/spec/ruby/library/ipaddr/new_spec.rb
+++ b/spec/ruby/library/ipaddr/new_spec.rb
@@ -3,9 +3,9 @@ require 'ipaddr'
 
 describe "IPAddr#new" do
   it "initializes IPAddr" do
-    ->{ IPAddr.new("3FFE:505:ffff::/48") }.should_not raise_error
-    ->{ IPAddr.new("0:0:0:1::")          }.should_not raise_error
-    ->{ IPAddr.new("2001:200:300::/48")  }.should_not raise_error
+    ->{ IPAddr.new("3FFE:505:ffff::/48") }.should_not.raise
+    ->{ IPAddr.new("0:0:0:1::")          }.should_not.raise
+    ->{ IPAddr.new("2001:200:300::/48")  }.should_not.raise
   end
 
   it "initializes IPAddr ipv6 address with short notation" do
@@ -27,8 +27,8 @@ describe "IPAddr#new" do
     a.to_s.should == "3ffe:505:2::"
     a.to_string.should == "3ffe:0505:0002:0000:0000:0000:0000:0000"
     a.family.should == Socket::AF_INET6
-    a.ipv4?.should == false
-    a.ipv6?.should == true
+    a.should_not.ipv4?
+    a.should.ipv6?
     a.inspect.should == "#<IPAddr: IPv6:3ffe:0505:0002:0000:0000:0000:0000:0000/ffff:ffff:ffff:0000:0000:0000:0000:0000>"
   end
 
@@ -51,8 +51,8 @@ describe "IPAddr#new" do
     a.to_s.should == "192.168.1.2"
     a.to_string.should == "192.168.1.2"
     a.family.should == Socket::AF_INET
-    a.ipv4?.should == true
-    a.ipv6?.should == false
+    a.should.ipv4?
+    a.should_not.ipv6?
   end
 
   it "initializes IPAddr ipv4 address with / subnet notation" do
@@ -79,7 +79,6 @@ describe "IPAddr#new" do
 
   it "raises on incorrect IPAddr strings" do
     [
-      ["fe80::1%fxp0"],
       ["::1/255.255.255.0"],
       [IPAddr.new("::1").to_i],
       ["::ffff:192.168.1.2/120", Socket::AF_INET],
@@ -87,7 +86,7 @@ describe "IPAddr#new" do
     ].each { |args|
       ->{
         IPAddr.new(*args)
-      }.should raise_error(ArgumentError)
+      }.should.raise(ArgumentError)
     }
   end
 end
diff --git a/spec/ruby/library/ipaddr/operator_spec.rb b/spec/ruby/library/ipaddr/operator_spec.rb
index f90c56009c..3337d22300 100644
--- a/spec/ruby/library/ipaddr/operator_spec.rb
+++ b/spec/ruby/library/ipaddr/operator_spec.rb
@@ -66,17 +66,17 @@ describe "IPAddr Operator" do
   end
 
   it "checks whether an address is included in a range" do
-    @a.should include(IPAddr.new("3ffe:505:2::"))
-    @a.should include(IPAddr.new("3ffe:505:2::1"))
-    @a.should_not include(IPAddr.new("3ffe:505:3::"))
+    @a.should.include?(IPAddr.new("3ffe:505:2::"))
+    @a.should.include?(IPAddr.new("3ffe:505:2::1"))
+    @a.should_not.include?(IPAddr.new("3ffe:505:3::"))
     net1 = IPAddr.new("192.168.2.0/24")
-    net1.should include(IPAddr.new("192.168.2.0"))
-    net1.should include(IPAddr.new("192.168.2.255"))
-    net1.should_not include(IPAddr.new("192.168.3.0"))
+    net1.should.include?(IPAddr.new("192.168.2.0"))
+    net1.should.include?(IPAddr.new("192.168.2.255"))
+    net1.should_not.include?(IPAddr.new("192.168.3.0"))
     # test with integer parameter
     int = (192 << 24) + (168 << 16) + (2 << 8) + 13
 
-    net1.should include(int)
-    net1.should_not include(int+255)
+    net1.should.include?(int)
+    net1.should_not.include?(int+255)
   end
 end
diff --git a/spec/ruby/library/ipaddr/reverse_spec.rb b/spec/ruby/library/ipaddr/reverse_spec.rb
index 6ebb343269..9bda60ca70 100644
--- a/spec/ruby/library/ipaddr/reverse_spec.rb
+++ b/spec/ruby/library/ipaddr/reverse_spec.rb
@@ -13,7 +13,7 @@ describe "IPAddr#ip6_arpa" do
     IPAddr.new("3ffe:505:2::f").ip6_arpa.should == "f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.arpa"
     ->{
       IPAddr.new("192.168.2.1").ip6_arpa
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
 
@@ -22,6 +22,6 @@ describe "IPAddr#ip6_int" do
     IPAddr.new("3ffe:505:2::f").ip6_int.should == "f.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.0.5.0.5.0.e.f.f.3.ip6.int"
     ->{
       IPAddr.new("192.168.2.1").ip6_int
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/irb/fixtures/irb.rb b/spec/ruby/library/irb/fixtures/irb.rb
new file mode 100644
index 0000000000..8d386dfda1
--- /dev/null
+++ b/spec/ruby/library/irb/fixtures/irb.rb
@@ -0,0 +1,3 @@
+a = 10
+
+binding.irb # rubocop:disable Lint/Debugger
diff --git a/spec/ruby/library/irb/irb_spec.rb b/spec/ruby/library/irb/irb_spec.rb
new file mode 100644
index 0000000000..2607c7ef33
--- /dev/null
+++ b/spec/ruby/library/irb/irb_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+require 'tmpdir'
+
+describe "Binding#irb" do
+  it "creates an IRB session with the binding in scope" do
+    irb_fixture = fixture __FILE__, "irb.rb"
+    envs = %w[IRBRC HOME XDG_CONFIG_HOME].to_h {|e| [e, nil]}
+
+    out = Dir.mktmpdir do |dir|
+      IO.popen([envs, *ruby_exe, irb_fixture, chdir: dir], "r+") do |pipe|
+        pipe.puts "a ** 2"
+        pipe.puts "exit"
+        pipe.readlines.map(&:chomp).reject(&:empty?)
+      end
+    end
+
+    out.last(3).should == ["a ** 2", "100", "exit"]
+  end
+end
diff --git a/spec/ruby/library/logger/device/close_spec.rb b/spec/ruby/library/logger/device/close_spec.rb
index d7d107fcce..1db5d582a7 100644
--- a/spec/ruby/library/logger/device/close_spec.rb
+++ b/spec/ruby/library/logger/device/close_spec.rb
@@ -15,17 +15,8 @@ describe "Logger::LogDevice#close" do
     rm_r @file_path
   end
 
-  ruby_version_is ""..."2.7" do
-    it "closes the LogDevice's stream" do
-      @device.close
-      -> { @device.write("Test") }.should complain(/\Alog writing failed\./)
-    end
-  end
-
-  ruby_version_is "2.7" do
-    it "closes the LogDevice's stream" do
-      @device.close
-      -> { @device.write("Test") }.should complain(/\Alog shifting failed\./)
-    end
+  it "closes the LogDevice's stream" do
+    @device.close
+    -> { @device.write("Test") }.should complain(/\Alog shifting failed\./)
   end
 end
diff --git a/spec/ruby/library/logger/device/new_spec.rb b/spec/ruby/library/logger/device/new_spec.rb
index 26a38c2b8c..c943e7fbe2 100644
--- a/spec/ruby/library/logger/device/new_spec.rb
+++ b/spec/ruby/library/logger/device/new_spec.rb
@@ -14,11 +14,11 @@ describe "Logger::LogDevice#new" do
 
   it "creates a new log device" do
     l = Logger::LogDevice.new(@log_file)
-    l.dev.should be_kind_of(File)
+    l.dev.should.is_a?(File)
   end
 
   it "receives an IO object to log there as first argument" do
-    @log_file.should be_kind_of(IO)
+    @log_file.should.is_a?(IO)
     l = Logger::LogDevice.new(@log_file)
     l.write("foo")
     @log_file.rewind
@@ -33,7 +33,7 @@ describe "Logger::LogDevice#new" do
 
     File.should.exist?(path)
     File.open(path) do |f|
-      f.readlines.should_not be_empty
+      f.readlines.should_not.empty?
     end
 
     rm_r path
@@ -42,6 +42,6 @@ describe "Logger::LogDevice#new" do
   it "receives options via a hash as second argument" do
     -> {
       Logger::LogDevice.new(STDERR, shift_age: 8, shift_size: 10)
-    }.should_not raise_error
+    }.should_not.raise
   end
 end
diff --git a/spec/ruby/library/logger/device/write_spec.rb b/spec/ruby/library/logger/device/write_spec.rb
index 5506bb2c38..87ecf2ad6a 100644
--- a/spec/ruby/library/logger/device/write_spec.rb
+++ b/spec/ruby/library/logger/device/write_spec.rb
@@ -35,17 +35,8 @@ describe "Logger::LogDevice#write" do
     rm_r path
   end
 
-  ruby_version_is ""..."2.7" do
-    it "fails if the device is already closed" do
-      @device.close
-      -> { @device.write "foo" }.should complain(/\Alog writing failed\./)
-    end
-  end
-
-  ruby_version_is "2.7" do
-    it "fails if the device is already closed" do
-      @device.close
-      -> { @device.write "foo" }.should complain(/\Alog shifting failed\./)
-    end
+  it "fails if the device is already closed" do
+    @device.close
+    -> { @device.write "foo" }.should complain(/\Alog shifting failed\./)
   end
 end
diff --git a/spec/ruby/library/logger/logger/add_spec.rb b/spec/ruby/library/logger/logger/add_spec.rb
index 3f709e18ba..98ac88f64f 100644
--- a/spec/ruby/library/logger/logger/add_spec.rb
+++ b/spec/ruby/library/logger/logger/add_spec.rb
@@ -56,7 +56,7 @@ describe "Logger#add" do
       @logger.log(nil, "test", "TestApp") do
         1+1
       end
-    }.should_not raise_error
+    }.should_not.raise
   end
 
   it "calls the block if message is nil" do
@@ -65,7 +65,7 @@ describe "Logger#add" do
       @logger.log(nil, nil, "TestApp") do
         temp = 1+1
       end
-    }.should_not raise_error
+    }.should_not.raise
     temp.should == 2
   end
 
@@ -75,7 +75,7 @@ describe "Logger#add" do
       @logger.log(nil, "not nil", "TestApp") do
         temp = 1+1
       end
-    }.should_not raise_error
+    }.should_not.raise
     temp.should == 0
   end
 end
diff --git a/spec/ruby/library/logger/logger/datetime_format_spec.rb b/spec/ruby/library/logger/logger/datetime_format_spec.rb
index 582b34bfda..75a7f6cc03 100644
--- a/spec/ruby/library/logger/logger/datetime_format_spec.rb
+++ b/spec/ruby/library/logger/logger/datetime_format_spec.rb
@@ -49,7 +49,7 @@ describe "Logger#datetime_format=" do
   end
 
   it "follows the Time#strftime format" do
-    -> { @logger.datetime_format = "%Y-%m" }.should_not raise_error
+    -> { @logger.datetime_format = "%Y-%m" }.should_not.raise
 
     regex = /\d{4}-\d{2}-\d{2}oo-\w+ar/
     @logger.datetime_format = "%Foo-%Bar"
diff --git a/spec/ruby/library/logger/logger/debug_spec.rb b/spec/ruby/library/logger/logger/debug_spec.rb
index d92c339232..9375ab0cc6 100644
--- a/spec/ruby/library/logger/logger/debug_spec.rb
+++ b/spec/ruby/library/logger/logger/debug_spec.rb
@@ -16,12 +16,12 @@ describe "Logger#debug?" do
 
   it "returns true if severity level allows debug messages" do
     @logger.level = Logger::DEBUG
-    @logger.debug?.should == true
+    @logger.should.debug?
   end
 
   it "returns false if severity level does not allow debug messages" do
     @logger.level = Logger::WARN
-    @logger.debug?.should == false
+    @logger.should_not.debug?
   end
 end
 
diff --git a/spec/ruby/library/logger/logger/error_spec.rb b/spec/ruby/library/logger/logger/error_spec.rb
index d5d0bd2d2f..42f1dbd883 100644
--- a/spec/ruby/library/logger/logger/error_spec.rb
+++ b/spec/ruby/library/logger/logger/error_spec.rb
@@ -16,12 +16,12 @@ describe "Logger#error?" do
 
   it "returns true if severity level allows printing errors" do
     @logger.level = Logger::INFO
-    @logger.error?.should == true
+    @logger.should.error?
   end
 
   it "returns false if severity level does not allow errors" do
     @logger.level = Logger::FATAL
-    @logger.error?.should == false
+    @logger.should_not.error?
   end
 end
 
diff --git a/spec/ruby/library/logger/logger/fatal_spec.rb b/spec/ruby/library/logger/logger/fatal_spec.rb
index 42d4341319..f12fa3a89f 100644
--- a/spec/ruby/library/logger/logger/fatal_spec.rb
+++ b/spec/ruby/library/logger/logger/fatal_spec.rb
@@ -16,12 +16,12 @@ describe "Logger#fatal?" do
 
   it "returns true if severity level allows fatal messages" do
     @logger.level = Logger::FATAL
-    @logger.fatal?.should == true
+    @logger.should.fatal?
   end
 
   it "returns false if severity level does not allow fatal messages" do
     @logger.level = Logger::UNKNOWN
-    @logger.fatal?.should == false
+    @logger.should_not.fatal?
   end
 end
 
diff --git a/spec/ruby/library/logger/logger/info_spec.rb b/spec/ruby/library/logger/logger/info_spec.rb
index 21eacbbb31..eb5dca48dd 100644
--- a/spec/ruby/library/logger/logger/info_spec.rb
+++ b/spec/ruby/library/logger/logger/info_spec.rb
@@ -16,12 +16,12 @@ describe "Logger#info?" do
 
   it "returns true if severity level allows info messages" do
     @logger.level = Logger::INFO
-    @logger.info?.should == true
+    @logger.should.info?
   end
 
   it "returns false if severity level does not allow info messages" do
     @logger.level = Logger::FATAL
-    @logger.info?.should == false
+    @logger.should_not.info?
   end
 end
 
diff --git a/spec/ruby/library/logger/logger/new_spec.rb b/spec/ruby/library/logger/logger/new_spec.rb
index d3100ee2d1..b311c96132 100644
--- a/spec/ruby/library/logger/logger/new_spec.rb
+++ b/spec/ruby/library/logger/logger/new_spec.rb
@@ -13,28 +13,28 @@ describe "Logger#new" do
     rm_r @file_path
   end
 
-   it "creates a new logger object" do
-     l = Logger.new(STDERR)
-     -> { l.add(Logger::WARN, "Foo") }.should output_to_fd(/Foo/, STDERR)
-   end
+  it "creates a new logger object" do
+    l = Logger.new(STDERR)
+    -> { l.add(Logger::WARN, "Foo") }.should output_to_fd(/Foo/, STDERR)
+  end
 
-   it "receives a logging device as first argument" do
-     l = Logger.new(@log_file)
-     l.add(Logger::WARN, "Test message")
+  it "receives a logging device as first argument" do
+    l = Logger.new(@log_file)
+    l.add(Logger::WARN, "Test message")
 
-     @log_file.rewind
-     LoggerSpecs.strip_date(@log_file.readline).should == "WARN -- : Test message\n"
-     l.close
-   end
+    @log_file.rewind
+    LoggerSpecs.strip_date(@log_file.readline).should == "WARN -- : Test message\n"
+    l.close
+  end
 
   it "receives a frequency rotation as second argument" do
-     -> { Logger.new(@log_file, "daily") }.should_not raise_error
-     -> { Logger.new(@log_file, "weekly") }.should_not raise_error
-     -> { Logger.new(@log_file, "monthly") }.should_not raise_error
+    -> { Logger.new(@log_file, "daily") }.should_not.raise
+    -> { Logger.new(@log_file, "weekly") }.should_not.raise
+    -> { Logger.new(@log_file, "monthly") }.should_not.raise
   end
 
   it "also receives a number of log files to keep as second argument" do
-    -> { Logger.new(@log_file, 1).close }.should_not raise_error
+    -> { Logger.new(@log_file, 1).close }.should_not.raise
   end
 
   it "receives a maximum logfile size as third argument" do
@@ -94,7 +94,7 @@ describe "Logger#new" do
     logger.formatter.should == formatter
   end
 
-  it "receives shift_period_suffix " do
+  it "receives shift_period_suffix" do
     shift_period_suffix = "%Y-%m-%d"
     path                = tmp("shift_period_suffix_test.log")
     now                 = Time.now
diff --git a/spec/ruby/library/logger/logger/unknown_spec.rb b/spec/ruby/library/logger/logger/unknown_spec.rb
index b174b8b2c9..4d37c9797e 100644
--- a/spec/ruby/library/logger/logger/unknown_spec.rb
+++ b/spec/ruby/library/logger/logger/unknown_spec.rb
@@ -29,7 +29,7 @@ describe "Logger#unknown" do
   end
 
   it "receives empty messages" do
-    -> { @logger.unknown("") }.should_not raise_error
+    -> { @logger.unknown("") }.should_not.raise
     @log_file.rewind
     LoggerSpecs.strip_date(@log_file.readlines.first).should ==  "ANY -- : \n"
   end
diff --git a/spec/ruby/library/logger/logger/warn_spec.rb b/spec/ruby/library/logger/logger/warn_spec.rb
index 6617b2b41a..0bca34824a 100644
--- a/spec/ruby/library/logger/logger/warn_spec.rb
+++ b/spec/ruby/library/logger/logger/warn_spec.rb
@@ -16,12 +16,12 @@ describe "Logger#warn?" do
 
   it "returns true if severity level allows printing warn messages" do
     @logger.level = Logger::WARN
-    @logger.warn?.should == true
+    @logger.should.warn?
   end
 
   it "returns false if severity level does not allow printing warn messages" do
     @logger.level = Logger::FATAL
-    @logger.warn?.should == false
+    @logger.should_not.warn?
   end
 end
 
diff --git a/spec/ruby/library/mathn/bignum/exponent_spec.rb b/spec/ruby/library/mathn/bignum/exponent_spec.rb
deleted file mode 100644
index ddd19ffdb4..0000000000
--- a/spec/ruby/library/mathn/bignum/exponent_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Bignum#**" do
-    before :each do
-      @bignum = bignum_value(47)
-    end
-
-    it "returns self raised to other (positive) power" do
-      (@bignum ** 4).should == 7237005577332262361485077344629993318496048279512298547155833600056910050625
-      (@bignum ** 1.2).should be_close(57262152889751597425762.57804, TOLERANCE)
-    end
-
-    it "returns a complex number when negative and raised to a fractional power" do
-      ((-@bignum) ** (1/3)).should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
-      ((-@bignum) ** (1.0/3)).should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/complex/Complex_spec.rb b/spec/ruby/library/mathn/complex/Complex_spec.rb
deleted file mode 100644
index 105902ed5d..0000000000
--- a/spec/ruby/library/mathn/complex/Complex_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Kernel#Complex" do
-    it "returns an Integer if imaginary part is 0" do
-      Complex(42,0).should == 42
-      Complex(42,0).should be_kind_of(Fixnum)
-      Complex(bignum_value,0).should == bignum_value
-      Complex(bignum_value,0).should be_kind_of(Bignum)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/fixnum/exponent_spec.rb b/spec/ruby/library/mathn/fixnum/exponent_spec.rb
deleted file mode 100644
index 160bf7f115..0000000000
--- a/spec/ruby/library/mathn/fixnum/exponent_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Fixnum#**" do
-    it "returns self raised to other (positive) power" do
-      (2 ** 4).should == 16
-      (2 ** 1.2).should be_close(2.2973967, TOLERANCE)
-    end
-
-    it "returns a complex number when negative and raised to a fractional power" do
-      ((-8) ** (1/3)).should be_close(Complex(1, 1.73205), TOLERANCE)
-      ((-8) ** (1.0/3)).should be_close(Complex(1, 1.73205), TOLERANCE)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/float/exponent_spec.rb b/spec/ruby/library/mathn/float/exponent_spec.rb
deleted file mode 100644
index 312119db00..0000000000
--- a/spec/ruby/library/mathn/float/exponent_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Float#**" do
-    it "returns self raised to other (positive) power" do
-      (2.0 ** 4).should == 16.0
-      (2.0 ** 1.2).should be_close(2.2973967, TOLERANCE)
-    end
-
-    it "returns a complex number when negative and raised to a fractional power" do
-      ((-8.0) ** (1/3)).should be_close(Complex(1, 1.73205), TOLERANCE)
-      ((-8.0) ** (1.0/3)).should be_close(Complex(1, 1.73205), TOLERANCE)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/integer/from_prime_division_spec.rb b/spec/ruby/library/mathn/integer/from_prime_division_spec.rb
deleted file mode 100644
index df2db6d8c1..0000000000
--- a/spec/ruby/library/mathn/integer/from_prime_division_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Integer.from_prime_division" do
-    it "reverses a prime factorization of an integer" do
-      Integer.from_prime_division([[2, 1], [3, 2], [7, 1]]).should == 126
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/integer/prime_division_spec.rb b/spec/ruby/library/mathn/integer/prime_division_spec.rb
deleted file mode 100644
index fb4a1c3fea..0000000000
--- a/spec/ruby/library/mathn/integer/prime_division_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Integer#prime_division" do
-    it "performs a prime factorization of a positive integer" do
-      100.prime_division.should == [[2, 2], [5, 2]]
-    end
-
-    # Proper handling of negative integers has been added to MRI trunk
-    # in revision 24091. Prior to that, all versions of MRI returned nonsense.
-    it "performs a prime factorization of a negative integer" do
-      -26.prime_division.should == [[-1, 1], [2, 1], [13, 1]]
-    end
-
-    it "raises a ZeroDivisionError when is called on zero" do
-      -> { 0.prime_division }.should raise_error(ZeroDivisionError)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/math/fixtures/classes.rb b/spec/ruby/library/mathn/math/fixtures/classes.rb
deleted file mode 100644
index 024732fa7a..0000000000
--- a/spec/ruby/library/mathn/math/fixtures/classes.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-class IncludesMath
-  include Math
-end
diff --git a/spec/ruby/library/mathn/math/rsqrt_spec.rb b/spec/ruby/library/mathn/math/rsqrt_spec.rb
deleted file mode 100644
index 6cb7595afe..0000000000
--- a/spec/ruby/library/mathn/math/rsqrt_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require_relative 'shared/rsqrt'
-
-  describe "Math#rsqrt" do
-    it_behaves_like :mathn_math_rsqrt, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:rsqrt)
-    end
-  end
-
-  describe "Math.rsqrt" do
-    it_behaves_like :mathn_math_rsqrt, :_, Math
-  end
-end
diff --git a/spec/ruby/library/mathn/math/shared/rsqrt.rb b/spec/ruby/library/mathn/math/shared/rsqrt.rb
deleted file mode 100644
index ea3d1b0cfc..0000000000
--- a/spec/ruby/library/mathn/math/shared/rsqrt.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require 'mathn'
-require_relative '../fixtures/classes'
-
-describe :mathn_math_rsqrt, shared: true do
-  it "returns the square root for Rational numbers" do
-    @object.send(:rsqrt, Rational(9, 25)).should == Rational(3, 5)
-    @object.send(:rsqrt, 16/64).should == Rational(1, 2)
-  end
-
-  it "returns the square root for positive numbers" do
-    @object.send(:rsqrt, 1).should == 1
-    @object.send(:rsqrt, 4.0).should == 2.0
-    @object.send(:rsqrt, 12.34).should == Math.sqrt!(12.34)
-  end
-
-  it "raises an Math::DomainError if the argument is a negative number" do
-    -> { @object.send(:rsqrt, -1) }.should raise_error(Math::DomainError)
-    -> { @object.send(:rsqrt, -4.0) }.should raise_error(Math::DomainError)
-    -> { @object.send(:rsqrt, -16/64) }.should raise_error(Math::DomainError)
-  end
-end
diff --git a/spec/ruby/library/mathn/math/shared/sqrt.rb b/spec/ruby/library/mathn/math/shared/sqrt.rb
deleted file mode 100644
index 5e6dae1d4f..0000000000
--- a/spec/ruby/library/mathn/math/shared/sqrt.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require 'mathn'
-require_relative '../fixtures/classes'
-
-describe :mathn_math_sqrt, shared: true do
-  it "returns the square root for Rational numbers" do
-    @object.send(:sqrt, Rational(9, 25)).should == Rational(3, 5)
-    @object.send(:sqrt, 16/64).should == Rational(1, 2)
-  end
-
-  it "returns the square root for Complex numbers" do
-    @object.send(:sqrt, Complex(1, 0)).should == 1
-  end
-
-  it "returns the square root for positive numbers" do
-    @object.send(:sqrt, 1).should == 1
-    @object.send(:sqrt, 4.0).should == 2.0
-    @object.send(:sqrt, 12.34).should == Math.sqrt!(12.34)
-  end
-
-  it "returns the square root for negative numbers" do
-    @object.send(:sqrt, -9).should == Complex(0, 3)
-    @object.send(:sqrt, -5.29).should == Complex(0, 2.3)
-    @object.send(:sqrt, -16/64).should == Complex(0, 1/2)
-  end
-end
diff --git a/spec/ruby/library/mathn/math/sqrt_spec.rb b/spec/ruby/library/mathn/math/sqrt_spec.rb
deleted file mode 100644
index 49cfe3600e..0000000000
--- a/spec/ruby/library/mathn/math/sqrt_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require_relative 'shared/sqrt'
-
-  describe "Math#rsqrt" do
-    it_behaves_like :mathn_math_sqrt, :_, IncludesMath.new
-
-    it "is a private instance method" do
-      IncludesMath.should have_private_instance_method(:sqrt)
-    end
-  end
-
-  describe "Math.rsqrt" do
-    it_behaves_like :mathn_math_sqrt, :_, Math
-  end
-end
diff --git a/spec/ruby/library/mathn/mathn_spec.rb b/spec/ruby/library/mathn/mathn_spec.rb
deleted file mode 100644
index 129c8f3288..0000000000
--- a/spec/ruby/library/mathn/mathn_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../spec_helper'
-
-describe "mathn" do
-  ruby_version_is "2.5" do
-    it "is no longer part of the standard library" do
-      -> {
-        require "mathn"
-      }.should raise_error(LoadError) { |e|
-        e.path.should == 'mathn'
-      }
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/rational/Rational_spec.rb b/spec/ruby/library/mathn/rational/Rational_spec.rb
deleted file mode 100644
index 9a34c99751..0000000000
--- a/spec/ruby/library/mathn/rational/Rational_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Kernel#Rational" do
-    it "returns an Integer if denominator divides numerator evenly" do
-      Rational(42,6).should == 7
-      Rational(42,6).should be_kind_of(Fixnum)
-      Rational(bignum_value,1).should == bignum_value
-      Rational(bignum_value,1).should be_kind_of(Bignum)
-    end
-  end
-end
diff --git a/spec/ruby/library/mathn/rational/inspect_spec.rb b/spec/ruby/library/mathn/rational/inspect_spec.rb
deleted file mode 100644
index cbf67ec0f3..0000000000
--- a/spec/ruby/library/mathn/rational/inspect_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.5' do
-  require 'mathn'
-
-  describe "Rational#inspect" do
-    it "returns a string representation of self" do
-      Rational(3, 4).inspect.should == "(3/4)"
-      Rational(-5, 8).inspect.should == "(-5/8)"
-      Rational(-1, -2).inspect.should == "(1/2)"
-      Rational(0, 2).inspect.should == "0"
-      Rational(bignum_value, 1).inspect.should == "#{bignum_value}"
-    end
-  end
-end
diff --git a/spec/ruby/library/matrix/antisymmetric_spec.rb b/spec/ruby/library/matrix/antisymmetric_spec.rb
index 3eb0f8b726..b4b8858f32 100644
--- a/spec/ruby/library/matrix/antisymmetric_spec.rb
+++ b/spec/ruby/library/matrix/antisymmetric_spec.rb
@@ -1,37 +1,36 @@
 require_relative '../../spec_helper'
+
 require 'matrix'
 
-ruby_version_is "2.6" do
-  describe "Matrix#antisymmetric?" do
-    it "returns true for an antisymmetric Matrix" do
-      Matrix[[0, -2, Complex(1, 3)], [2, 0, 5], [-Complex(1, 3), -5, 0]].antisymmetric?.should be_true
-    end
+describe "Matrix#antisymmetric?" do
+  it "returns true for an antisymmetric Matrix" do
+    Matrix[[0, -2, Complex(1, 3)], [2, 0, 5], [-Complex(1, 3), -5, 0]].antisymmetric?.should == true
+  end
 
-    it "returns true for a 0x0 empty matrix" do
-      Matrix.empty.antisymmetric?.should be_true
-    end
+  it "returns true for a 0x0 empty matrix" do
+    Matrix.empty.antisymmetric?.should == true
+  end
 
-    it "returns false for non-antisymmetric matrices" do
-      [
-        Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
-        Matrix[[1, -2, 3], [2, 0, 6], [-3, -6, 0]],  # wrong diagonal element
-        Matrix[[0, 2, -3], [2, 0, 6], [-3, 6, 0]]    # only signs wrong
-      ].each do |matrix|
-        matrix.antisymmetric?.should be_false
-      end
+  it "returns false for non-antisymmetric matrices" do
+    [
+      Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
+      Matrix[[1, -2, 3], [2, 0, 6], [-3, -6, 0]],  # wrong diagonal element
+      Matrix[[0, 2, -3], [2, 0, 6], [-3, 6, 0]]    # only signs wrong
+    ].each do |matrix|
+      matrix.antisymmetric?.should == false
     end
+  end
 
-    it "raises an error for rectangular matrices" do
-      [
-        Matrix[[0], [0]],
-        Matrix[[0, 0]],
-        Matrix.empty(0, 2),
-        Matrix.empty(2, 0),
-      ].each do |rectangular_matrix|
-        -> {
-          rectangular_matrix.antisymmetric?
-        }.should raise_error(Matrix::ErrDimensionMismatch)
-      end
+  it "raises an error for rectangular matrices" do
+    [
+      Matrix[[0], [0]],
+      Matrix[[0, 0]],
+      Matrix.empty(0, 2),
+      Matrix.empty(2, 0),
+    ].each do |rectangular_matrix|
+      -> {
+        rectangular_matrix.antisymmetric?
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/build_spec.rb b/spec/ruby/library/matrix/build_spec.rb
index 6d8017a3df..49eb2e69a5 100644
--- a/spec/ruby/library/matrix/build_spec.rb
+++ b/spec/ruby/library/matrix/build_spec.rb
@@ -6,7 +6,7 @@ describe "Matrix.build" do
 
   it "returns a Matrix object of the given size" do
     m = Matrix.build(3, 4){1}
-    m.should be_an_instance_of(Matrix)
+    m.should.instance_of?(Matrix)
     m.row_size.should == 3
     m.column_size.should == 4
   end
@@ -24,32 +24,32 @@ describe "Matrix.build" do
 
   it "returns an Enumerator is no block is given" do
     enum = Matrix.build(2, 1)
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.each{1}.should == Matrix[[1], [1]]
   end
 
   it "requires integers as parameters" do
-    -> { Matrix.build("1", "2"){1} }.should raise_error(TypeError)
-    -> { Matrix.build(nil, nil){1} }.should raise_error(TypeError)
-    -> { Matrix.build(1..2){1} }.should raise_error(TypeError)
+    -> { Matrix.build("1", "2"){1} }.should.raise(TypeError)
+    -> { Matrix.build(nil, nil){1} }.should.raise(TypeError)
+    -> { Matrix.build(1..2){1} }.should.raise(TypeError)
   end
 
   it "requires non-negative integers" do
-    -> { Matrix.build(-1, 1){1} }.should raise_error(ArgumentError)
-    -> { Matrix.build(+1,-1){1} }.should raise_error(ArgumentError)
+    -> { Matrix.build(-1, 1){1} }.should.raise(ArgumentError)
+    -> { Matrix.build(+1,-1){1} }.should.raise(ArgumentError)
   end
 
   it "returns empty Matrix if one argument is zero" do
     m = Matrix.build(0, 3){
       raise "Should not yield"
     }
-    m.should be_empty
+    m.should.empty?
     m.column_size.should == 3
 
     m = Matrix.build(3, 0){
       raise "Should not yield"
     }
-    m.should be_empty
+    m.should.empty?
     m.row_size.should == 3
   end
 
@@ -68,6 +68,6 @@ end
 
 describe "for a subclass of Matrix" do
   it "returns an instance of that subclass" do
-    MatrixSub.build(3){1}.should be_an_instance_of(MatrixSub)
+    MatrixSub.build(3){1}.should.instance_of?(MatrixSub)
   end
 end
diff --git a/spec/ruby/library/matrix/clone_spec.rb b/spec/ruby/library/matrix/clone_spec.rb
index 74e5bf157e..51aefc6010 100644
--- a/spec/ruby/library/matrix/clone_spec.rb
+++ b/spec/ruby/library/matrix/clone_spec.rb
@@ -9,17 +9,17 @@ describe "Matrix#clone" do
 
   it "returns a shallow copy of the matrix" do
     b = @a.clone
-    @a.should_not equal(b)
-    b.should be_kind_of(Matrix)
+    @a.should_not.equal?(b)
+    b.should.is_a?(Matrix)
     b.should == @a
     0.upto(@a.row_size - 1) do |i|
-      @a.row(i).should_not equal(b.row(i))
+      @a.row(i).should_not.equal?(b.row(i))
     end
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.clone.should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.clone.should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/coerce_spec.rb b/spec/ruby/library/matrix/coerce_spec.rb
index 280243d372..6032dd2f62 100644
--- a/spec/ruby/library/matrix/coerce_spec.rb
+++ b/spec/ruby/library/matrix/coerce_spec.rb
@@ -2,7 +2,7 @@ require_relative '../../spec_helper'
 require 'matrix'
 
 describe "Matrix#coerce" do
-  it "allows the division of fixnum by a Matrix " do
+  it "allows the division of integer by a Matrix" do
     (1/Matrix[[0,1],[-1,0]]).should == Matrix[[0,-1],[1,0]]
   end
 end
diff --git a/spec/ruby/library/matrix/column_spec.rb b/spec/ruby/library/matrix/column_spec.rb
index 1f3c80964a..d5d8c80c1a 100644
--- a/spec/ruby/library/matrix/column_spec.rb
+++ b/spec/ruby/library/matrix/column_spec.rb
@@ -21,7 +21,7 @@ describe "Matrix#column" do
   end
 
   it "returns self when called with a block" do
-    @m.column(0) { |x| x }.should equal(@m)
+    @m.column(0) { |x| x }.should.equal?(@m)
   end
 
   it "returns nil when out of bounds" do
@@ -29,7 +29,7 @@ describe "Matrix#column" do
   end
 
   it "never yields when out of bounds" do
-    -> { @m.column(3){ raise } }.should_not raise_error
-    -> { @m.column(-4){ raise } }.should_not raise_error
+    -> { @m.column(3){ raise } }.should_not.raise
+    -> { @m.column(-4){ raise } }.should_not.raise
   end
 end
diff --git a/spec/ruby/library/matrix/column_vector_spec.rb b/spec/ruby/library/matrix/column_vector_spec.rb
index 47e866a8d5..d86c3f9e42 100644
--- a/spec/ruby/library/matrix/column_vector_spec.rb
+++ b/spec/ruby/library/matrix/column_vector_spec.rb
@@ -6,20 +6,20 @@ describe "Matrix.column_vector" do
 
   it "returns a single column Matrix when called with an Array" do
     m = Matrix.column_vector([4,5,6])
-    m.should be_an_instance_of(Matrix)
+    m.should.instance_of?(Matrix)
     m.should == Matrix[ [4],[5],[6] ]
   end
 
   it "returns an empty Matrix when called with an empty Array" do
     m = Matrix.column_vector([])
-    m.should be_an_instance_of(Matrix)
+    m.should.instance_of?(Matrix)
     m.row_size.should == 0
     m.column_size.should == 1
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.column_vector([4,5,6]).should be_an_instance_of(MatrixSub)
+      MatrixSub.column_vector([4,5,6]).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/column_vectors_spec.rb b/spec/ruby/library/matrix/column_vectors_spec.rb
index b0cb6f914c..7ac6871e7f 100644
--- a/spec/ruby/library/matrix/column_vectors_spec.rb
+++ b/spec/ruby/library/matrix/column_vectors_spec.rb
@@ -8,11 +8,11 @@ describe "Matrix#column_vectors" do
   end
 
   it "returns an Array" do
-    Matrix[ [1,2], [3,4] ].column_vectors.should be_an_instance_of(Array)
+    Matrix[ [1,2], [3,4] ].column_vectors.should.instance_of?(Array)
   end
 
   it "returns an Array of Vectors" do
-    @vectors.all? {|v| v.should be_an_instance_of(Vector)}
+    @vectors.all? {|v| v.should.instance_of?(Vector)}
   end
 
   it "returns each column as a Vector" do
diff --git a/spec/ruby/library/matrix/columns_spec.rb b/spec/ruby/library/matrix/columns_spec.rb
index 3095fdd7af..ac9587899d 100644
--- a/spec/ruby/library/matrix/columns_spec.rb
+++ b/spec/ruby/library/matrix/columns_spec.rb
@@ -10,7 +10,7 @@ describe "Matrix.columns" do
   end
 
   it "creates a Matrix from argument columns" do
-    @m.should be_an_instance_of(Matrix)
+    @m.should.instance_of?(Matrix)
     @m.column(0).to_a.should == @a
     @m.column(1).to_a.should == @b
   end
@@ -36,7 +36,7 @@ describe "Matrix.columns" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.columns([[1]]).should be_an_instance_of(MatrixSub)
+      MatrixSub.columns([[1]]).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/constructor_spec.rb b/spec/ruby/library/matrix/constructor_spec.rb
index 70d77babbb..026525f36d 100644
--- a/spec/ruby/library/matrix/constructor_spec.rb
+++ b/spec/ruby/library/matrix/constructor_spec.rb
@@ -5,10 +5,10 @@ require 'matrix'
 describe "Matrix.[]" do
 
   it "requires arrays as parameters" do
-    -> { Matrix[5] }.should raise_error(TypeError)
-    -> { Matrix[nil] }.should raise_error(TypeError)
-    -> { Matrix[1..2] }.should raise_error(TypeError)
-    -> { Matrix[[1, 2], 3] }.should raise_error(TypeError)
+    -> { Matrix[5] }.should.raise(TypeError)
+    -> { Matrix[nil] }.should.raise(TypeError)
+    -> { Matrix[1..2] }.should.raise(TypeError)
+    -> { Matrix[[1, 2], 3] }.should.raise(TypeError)
   end
 
   it "creates an empty Matrix with no arguments" do
@@ -18,15 +18,13 @@ describe "Matrix.[]" do
   end
 
   it "raises for non-rectangular matrices" do
-    ->{ Matrix[ [0], [0,1] ] }.should \
-      raise_error(Matrix::ErrDimensionMismatch)
-    ->{ Matrix[ [0,1], [0,1,2], [0,1] ]}.should \
-      raise_error(Matrix::ErrDimensionMismatch)
+    ->{ Matrix[ [0], [0,1] ] }.should.raise(Matrix::ErrDimensionMismatch)
+    ->{ Matrix[ [0,1], [0,1,2], [0,1] ]}.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "accepts vector arguments" do
     a = Matrix[Vector[1, 2], Vector[3, 4]]
-    a.should be_an_instance_of(Matrix)
+    a.should.instance_of?(Matrix)
     a.should == Matrix[ [1, 2], [3, 4] ]
   end
 
@@ -38,7 +36,7 @@ describe "Matrix.[]" do
 
 
   it "returns a Matrix object" do
-    Matrix[ [1] ].should be_an_instance_of(Matrix)
+    Matrix[ [1] ].should.instance_of?(Matrix)
   end
 
   it "can create an nxn Matrix" do
@@ -59,7 +57,7 @@ describe "Matrix.[]" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub[ [20,30], [40.5, 9] ].should be_an_instance_of(MatrixSub)
+      MatrixSub[ [20,30], [40.5, 9] ].should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/diagonal_spec.rb b/spec/ruby/library/matrix/diagonal_spec.rb
index ef9738e73e..ee84ac8c28 100644
--- a/spec/ruby/library/matrix/diagonal_spec.rb
+++ b/spec/ruby/library/matrix/diagonal_spec.rb
@@ -8,7 +8,7 @@ describe "Matrix.diagonal" do
   end
 
   it "returns an object of type Matrix" do
-    @m.should be_kind_of(Matrix)
+    @m.should.is_a?(Matrix)
   end
 
   it "returns a square Matrix of the right size" do
@@ -34,27 +34,27 @@ describe "Matrix.diagonal" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.diagonal(1).should be_an_instance_of(MatrixSub)
+      MatrixSub.diagonal(1).should.instance_of?(MatrixSub)
     end
   end
 end
 
 describe "Matrix.diagonal?" do
   it "returns true for a diagonal Matrix" do
-    Matrix.diagonal([1, 2, 3]).diagonal?.should be_true
+    Matrix.diagonal([1, 2, 3]).diagonal?.should == true
   end
 
   it "returns true for a zero square Matrix" do
-    Matrix.zero(3).diagonal?.should be_true
+    Matrix.zero(3).diagonal?.should == true
   end
 
   it "returns false for a non diagonal square Matrix" do
-    Matrix[[0, 1], [0, 0]].diagonal?.should be_false
-    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].diagonal?.should be_false
+    Matrix[[0, 1], [0, 0]].diagonal?.should == false
+    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].diagonal?.should == false
   end
 
   it "returns true for an empty 0x0 matrix" do
-    Matrix.empty(0,0).diagonal?.should be_true
+    Matrix.empty(0,0).diagonal?.should == true
   end
 
   it "raises an error for rectangular matrices" do
@@ -66,7 +66,7 @@ describe "Matrix.diagonal?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.diagonal?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/divide_spec.rb b/spec/ruby/library/matrix/divide_spec.rb
index 2e3bb85bf6..711a5189e4 100644
--- a/spec/ruby/library/matrix/divide_spec.rb
+++ b/spec/ruby/library/matrix/divide_spec.rb
@@ -30,25 +30,25 @@ describe "Matrix#/" do
   end
 
   it "raises a Matrix::ErrDimensionMismatch if the matrices are different sizes" do
-    -> { @a / Matrix[ [1] ] }.should raise_error(Matrix::ErrDimensionMismatch)
+    -> { @a / Matrix[ [1] ] }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "returns an instance of Matrix" do
-    (@a / @b).should be_kind_of(Matrix)
+    (@a / @b).should.is_a?(Matrix)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
       m = MatrixSub.ins
-      (m/m).should be_an_instance_of(MatrixSub)
-      (m/1).should be_an_instance_of(MatrixSub)
+      (m/m).should.instance_of?(MatrixSub)
+      (m/1).should.instance_of?(MatrixSub)
     end
   end
 
   it "raises a TypeError if other is of wrong type" do
-    -> { @a / nil        }.should raise_error(TypeError)
-    -> { @a / "a"        }.should raise_error(TypeError)
-    -> { @a / [ [1, 2] ] }.should raise_error(TypeError)
-    -> { @a / Object.new }.should raise_error(TypeError)
+    -> { @a / nil        }.should.raise(TypeError)
+    -> { @a / "a"        }.should.raise(TypeError)
+    -> { @a / [ [1, 2] ] }.should.raise(TypeError)
+    -> { @a / Object.new }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/matrix/each_spec.rb b/spec/ruby/library/matrix/each_spec.rb
index f3b0f01867..b4bfd3c76f 100644
--- a/spec/ruby/library/matrix/each_spec.rb
+++ b/spec/ruby/library/matrix/each_spec.rb
@@ -9,12 +9,12 @@ describe "Matrix#each" do
 
   it "returns an Enumerator when called without a block" do
     enum = @m.each
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == @result
   end
 
   it "returns self" do
-    @m.each{}.should equal(@m)
+    @m.each{}.should.equal?(@m)
   end
 
   it "yields the elements starting with the those of the first row" do
@@ -33,13 +33,13 @@ describe "Matrix#each with an argument" do
   it "raises an ArgumentError for unrecognized argument" do
     -> {
       @m.each("all"){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.each(nil){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.each(:left){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "yields the rights elements when passed :diagonal" do
diff --git a/spec/ruby/library/matrix/each_with_index_spec.rb b/spec/ruby/library/matrix/each_with_index_spec.rb
index a005b88621..17e3f3f44c 100644
--- a/spec/ruby/library/matrix/each_with_index_spec.rb
+++ b/spec/ruby/library/matrix/each_with_index_spec.rb
@@ -16,12 +16,12 @@ describe "Matrix#each_with_index" do
 
   it "returns an Enumerator when called without a block" do
     enum = @m.each_with_index
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == @result
   end
 
   it "returns self" do
-    @m.each_with_index{}.should equal(@m)
+    @m.each_with_index{}.should.equal?(@m)
   end
 
   it "yields the elements starting with the those of the first row" do
@@ -40,13 +40,13 @@ describe "Matrix#each_with_index with an argument" do
   it "raises an ArgumentError for unrecognized argument" do
     -> {
       @m.each_with_index("all"){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.each_with_index(nil){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.each_with_index(:left){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "yields the rights elements when passed :diagonal" do
diff --git a/spec/ruby/library/matrix/eigenvalue_decomposition/initialize_spec.rb b/spec/ruby/library/matrix/eigenvalue_decomposition/initialize_spec.rb
index 8438f63133..cbda82a16a 100644
--- a/spec/ruby/library/matrix/eigenvalue_decomposition/initialize_spec.rb
+++ b/spec/ruby/library/matrix/eigenvalue_decomposition/initialize_spec.rb
@@ -5,16 +5,16 @@ describe "Matrix::EigenvalueDecomposition#initialize" do
   it "raises an error if argument is not a matrix" do
     -> {
       Matrix::EigenvalueDecomposition.new([[]])
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
     -> {
       Matrix::EigenvalueDecomposition.new(42)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises an error if matrix is not square" do
     -> {
       Matrix::EigenvalueDecomposition.new(Matrix[[1, 2]])
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "never hangs" do
diff --git a/spec/ruby/library/matrix/element_reference_spec.rb b/spec/ruby/library/matrix/element_reference_spec.rb
index b950d1c391..c6804b3846 100644
--- a/spec/ruby/library/matrix/element_reference_spec.rb
+++ b/spec/ruby/library/matrix/element_reference_spec.rb
@@ -16,8 +16,8 @@ describe "Matrix#[]" do
   end
 
   it "returns nil for an invalid index pair" do
-    @m[8,1].should be_nil
-    @m[1,8].should be_nil
+    @m[8,1].should == nil
+    @m[1,8].should == nil
   end
 
 end
diff --git a/spec/ruby/library/matrix/empty_spec.rb b/spec/ruby/library/matrix/empty_spec.rb
index 5f294711db..7b0f0af9eb 100644
--- a/spec/ruby/library/matrix/empty_spec.rb
+++ b/spec/ruby/library/matrix/empty_spec.rb
@@ -4,20 +4,20 @@ require 'matrix'
 
 describe "Matrix#empty?" do
   it "returns true when the Matrix is empty" do
-    Matrix[ ].empty?.should be_true
-    Matrix[ [], [], [] ].empty?.should be_true
-    Matrix[ [], [], [] ].transpose.empty?.should be_true
+    Matrix[ ].empty?.should == true
+    Matrix[ [], [], [] ].empty?.should == true
+    Matrix[ [], [], [] ].transpose.empty?.should == true
   end
 
   it "returns false when the Matrix has elements" do
-    Matrix[ [1, 2] ].empty?.should be_false
-    Matrix[ [1], [2] ].empty?.should be_false
+    Matrix[ [1, 2] ].empty?.should == false
+    Matrix[ [1], [2] ].empty?.should == false
   end
 
   it "doesn't accept any parameter" do
     ->{
       Matrix[ [1, 2] ].empty?(42)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
 
@@ -40,29 +40,29 @@ describe "Matrix.empty" do
   it "does not accept more than two parameters" do
     ->{
       Matrix.empty(1, 2, 3)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if both dimensions are > 0" do
     ->{
       Matrix.empty(1, 2)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "raises an error if any dimension is < 0" do
     ->{
       Matrix.empty(-2, 0)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
 
     ->{
       Matrix.empty(0, -2)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
 end
 
 describe "for a subclass of Matrix" do
   it "returns an instance of that subclass" do
-    MatrixSub.empty(0, 1).should be_an_instance_of(MatrixSub)
+    MatrixSub.empty(0, 1).should.instance_of?(MatrixSub)
   end
 end
diff --git a/spec/ruby/library/matrix/eql_spec.rb b/spec/ruby/library/matrix/eql_spec.rb
index ea26c3320d..cda122f4d8 100644
--- a/spec/ruby/library/matrix/eql_spec.rb
+++ b/spec/ruby/library/matrix/eql_spec.rb
@@ -6,6 +6,6 @@ describe "Matrix#eql?" do
   it_behaves_like :equal, :eql?
 
   it "returns false if some elements are == but not eql?" do
-    Matrix[[1, 2],[3, 4]].eql?(Matrix[[1, 2],[3, 4.0]]).should be_false
+    Matrix[[1, 2],[3, 4]].eql?(Matrix[[1, 2],[3, 4.0]]).should == false
   end
 end
diff --git a/spec/ruby/library/matrix/exponent_spec.rb b/spec/ruby/library/matrix/exponent_spec.rb
index 447c962967..4cbe63587d 100644
--- a/spec/ruby/library/matrix/exponent_spec.rb
+++ b/spec/ruby/library/matrix/exponent_spec.rb
@@ -17,21 +17,32 @@ describe "Matrix#**" do
 
     it "raises a ErrDimensionMismatch for non square matrices" do
       m = Matrix[ [1, 1], [1, 2], [2, 3]]
-      -> { m ** 3 }.should raise_error(Matrix::ErrDimensionMismatch)
-      -> { m ** 0 }.should raise_error(Matrix::ErrDimensionMismatch)
+      -> { m ** 3 }.should.raise(Matrix::ErrDimensionMismatch)
+      -> { m ** 0 }.should.raise(Matrix::ErrDimensionMismatch)
     end
 
-    describe "that is <= 0" do
+    describe "that is < 0" do
       it "returns the inverse of **(-n)" do
         m = Matrix[ [1, 1], [1, 2] ]
         (m ** -2).should == Matrix[ [5, -3], [-3, 2]]
         (m ** -4).should == (m.inverse ** 4)
       end
 
-      it "raises a ErrDimensionMismatch for irregular matrices" do
+      it "raises a ErrNotRegular for irregular matrices" do
         m = Matrix[ [1, 1], [1, 1] ]
-        -> { m ** -2 }.should raise_error(Matrix::ErrNotRegular)
-        -> { m ** 0 }.should raise_error(Matrix::ErrNotRegular)
+        -> { m ** -2 }.should.raise(Matrix::ErrNotRegular)
+      end
+    end
+
+    describe "that is 0" do
+      it "returns the identity for square matrices" do
+        m = Matrix[ [1, 1], [1, 1] ]
+        (m ** 0).should == Matrix.identity(2)
+      end
+
+      it "raises an ErrDimensionMismatch for non-square matrices" do
+        m = Matrix[ [1, 1] ]
+        -> { m ** 0 }.should.raise(Matrix::ErrDimensionMismatch)
       end
     end
   end
@@ -45,7 +56,7 @@ describe "Matrix#**" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      (MatrixSub.ins ** 1).should be_an_instance_of(MatrixSub)
+      (MatrixSub.ins ** 1).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/find_index_spec.rb b/spec/ruby/library/matrix/find_index_spec.rb
index c2bfa6d61a..c7278fd449 100644
--- a/spec/ruby/library/matrix/find_index_spec.rb
+++ b/spec/ruby/library/matrix/find_index_spec.rb
@@ -8,12 +8,12 @@ describe "Matrix#find_index without any argument" do
 
   it "returns an Enumerator when called without a block" do
     enum = @m.find_index
-    enum.should be_an_instance_of(Enumerator)
+    enum.should.instance_of?(Enumerator)
     enum.to_a.should == [1, 2, 3, 4, 5, 6, 7, 8]
   end
 
   it "returns nil if the block is always false" do
-    @m.find_index{false}.should be_nil
+    @m.find_index{false}.should == nil
   end
 
   it "returns the first index for which the block is true" do
@@ -48,7 +48,7 @@ describe "Matrix#find_index with a subselection argument" do
     it "returns an Enumerator when called without a block" do
       @tests.each do |matrix, h|
         h.each do |selector, result|
-          matrix.find_index(selector).should be_an_instance_of(Enumerator)
+          matrix.find_index(selector).should.instance_of?(Enumerator)
         end
       end
     end
@@ -116,7 +116,7 @@ describe "Matrix#find_index with only a generic argument" do
   end
 
   it "returns nil if the value is not found" do
-    @m.find_index(42).should be_nil
+    @m.find_index(42).should == nil
   end
 
   it "returns the first index for of the requested value" do
@@ -132,15 +132,15 @@ describe "Matrix#find_index with two arguments" do
   it "raises an ArgumentError for an unrecognized last argument" do
     -> {
       @m.find_index(1, "all"){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.find_index(1, nil){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.find_index(1, :left){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
     -> {
       @m.find_index(:diagonal, 1){}
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/matrix/hash_spec.rb b/spec/ruby/library/matrix/hash_spec.rb
index fac9a06527..27bf7b9751 100644
--- a/spec/ruby/library/matrix/hash_spec.rb
+++ b/spec/ruby/library/matrix/hash_spec.rb
@@ -3,8 +3,8 @@ require 'matrix'
 
 describe "Matrix#hash" do
 
-  it "returns a Fixnum" do
-    Matrix[ [1,2] ].hash.should be_an_instance_of(Fixnum)
+  it "returns an Integer" do
+    Matrix[ [1,2] ].hash.should.instance_of?(Integer)
   end
 
   it "returns the same value for the same matrix" do
diff --git a/spec/ruby/library/matrix/hermitian_spec.rb b/spec/ruby/library/matrix/hermitian_spec.rb
index 177ca64d83..94d0dbe6b6 100644
--- a/spec/ruby/library/matrix/hermitian_spec.rb
+++ b/spec/ruby/library/matrix/hermitian_spec.rb
@@ -3,15 +3,15 @@ require 'matrix'
 
 describe "Matrix.hermitian?" do
   it "returns true for a hermitian Matrix" do
-    Matrix[[1, 2, Complex(0, 3)], [2, 4, 5], [Complex(0, -3), 5, 6]].hermitian?.should be_true
+    Matrix[[1, 2, Complex(0, 3)], [2, 4, 5], [Complex(0, -3), 5, 6]].hermitian?.should == true
   end
 
   it "returns true for a 0x0 empty matrix" do
-    Matrix.empty.hermitian?.should be_true
+    Matrix.empty.hermitian?.should == true
   end
 
   it "returns false for an asymmetric Matrix" do
-    Matrix[[1, 2],[-2, 1]].hermitian?.should be_false
+    Matrix[[1, 2],[-2, 1]].hermitian?.should == false
   end
 
   it "raises an error for rectangular matrices" do
@@ -23,12 +23,12 @@ describe "Matrix.hermitian?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.hermitian?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 
   it "returns false for a matrix with complex values on the diagonal" do
-    Matrix[[Complex(1,1)]].hermitian?.should be_false
-    Matrix[[Complex(1,0)]].hermitian?.should be_true
+    Matrix[[Complex(1,1)]].hermitian?.should == false
+    Matrix[[Complex(1,0)]].hermitian?.should == true
   end
 end
diff --git a/spec/ruby/library/matrix/lower_triangular_spec.rb b/spec/ruby/library/matrix/lower_triangular_spec.rb
index f3aa4501f4..7e8688fd9b 100644
--- a/spec/ruby/library/matrix/lower_triangular_spec.rb
+++ b/spec/ruby/library/matrix/lower_triangular_spec.rb
@@ -3,22 +3,22 @@ require 'matrix'
 
 describe "Matrix.lower_triangular?" do
   it "returns true for a square lower triangular Matrix" do
-    Matrix[[1, 0, 0], [1, 2, 0], [1, 2, 3]].lower_triangular?.should be_true
-    Matrix.diagonal([1, 2, 3]).lower_triangular?.should be_true
-    Matrix[[1, 0], [1, 2], [1, 2], [1, 2]].lower_triangular?.should be_true
-    Matrix[[1, 0, 0, 0], [1, 2, 0, 0]].lower_triangular?.should be_true
+    Matrix[[1, 0, 0], [1, 2, 0], [1, 2, 3]].lower_triangular?.should == true
+    Matrix.diagonal([1, 2, 3]).lower_triangular?.should == true
+    Matrix[[1, 0], [1, 2], [1, 2], [1, 2]].lower_triangular?.should == true
+    Matrix[[1, 0, 0, 0], [1, 2, 0, 0]].lower_triangular?.should == true
   end
 
   it "returns true for an empty Matrix" do
-    Matrix.empty(3, 0).lower_triangular?.should be_true
-    Matrix.empty(0, 3).lower_triangular?.should be_true
-    Matrix.empty(0, 0).lower_triangular?.should be_true
+    Matrix.empty(3, 0).lower_triangular?.should == true
+    Matrix.empty(0, 3).lower_triangular?.should == true
+    Matrix.empty(0, 0).lower_triangular?.should == true
   end
 
   it "returns false for a non lower triangular square Matrix" do
-    Matrix[[0, 1], [0, 0]].lower_triangular?.should be_false
-    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].lower_triangular?.should be_false
-    Matrix[[0, 1], [0, 0], [0, 0], [0, 0]].lower_triangular?.should be_false
-    Matrix[[0, 0, 0, 1], [0, 0, 0, 0]].lower_triangular?.should be_false
+    Matrix[[0, 1], [0, 0]].lower_triangular?.should == false
+    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].lower_triangular?.should == false
+    Matrix[[0, 1], [0, 0], [0, 0], [0, 0]].lower_triangular?.should == false
+    Matrix[[0, 0, 0, 1], [0, 0, 0, 0]].lower_triangular?.should == false
   end
 end
diff --git a/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb b/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb
index 9d733066c1..98ac5c71a3 100644
--- a/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb
@@ -15,7 +15,7 @@ describe "Matrix::LUPDecomposition#determinant" do
       lup = m.lup
       -> {
         lup.determinant
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/lup_decomposition/initialize_spec.rb b/spec/ruby/library/matrix/lup_decomposition/initialize_spec.rb
index 36afb349e6..b813757525 100644
--- a/spec/ruby/library/matrix/lup_decomposition/initialize_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/initialize_spec.rb
@@ -5,9 +5,9 @@ describe "Matrix::LUPDecomposition#initialize" do
   it "raises an error if argument is not a matrix" do
     -> {
       Matrix::LUPDecomposition.new([[]])
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
     -> {
       Matrix::LUPDecomposition.new(42)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/matrix/lup_decomposition/l_spec.rb b/spec/ruby/library/matrix/lup_decomposition/l_spec.rb
index 9514ab5d06..0a6797cc85 100644
--- a/spec/ruby/library/matrix/lup_decomposition/l_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/l_spec.rb
@@ -13,6 +13,6 @@ describe "Matrix::LUPDecomposition#l" do
   end
 
   it "returns a lower triangular matrix" do
-    @l.lower_triangular?.should be_true
+    @l.lower_triangular?.should == true
   end
 end
diff --git a/spec/ruby/library/matrix/lup_decomposition/p_spec.rb b/spec/ruby/library/matrix/lup_decomposition/p_spec.rb
index c7b5e9196e..2c44399b79 100644
--- a/spec/ruby/library/matrix/lup_decomposition/p_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/p_spec.rb
@@ -13,6 +13,6 @@ describe "Matrix::LUPDecomposition#p" do
   end
 
   it "returns a permutation matrix" do
-    @p.permutation?.should be_true
+    @p.permutation?.should == true
   end
 end
diff --git a/spec/ruby/library/matrix/lup_decomposition/solve_spec.rb b/spec/ruby/library/matrix/lup_decomposition/solve_spec.rb
index 66242627e9..9927e96727 100644
--- a/spec/ruby/library/matrix/lup_decomposition/solve_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/solve_spec.rb
@@ -8,7 +8,7 @@ describe "Matrix::LUPDecomposition#solve" do
       lu = Matrix::LUPDecomposition.new(a)
       -> {
         lu.solve(a)
-      }.should raise_error(Matrix::ErrNotRegular)
+      }.should.raise(Matrix::ErrNotRegular)
     end
 
     describe "for non singular matrices" do
@@ -33,7 +33,7 @@ describe "Matrix::LUPDecomposition#solve" do
         values = Matrix[[1, 2, 3, 4], [0, 1, 2, 3]]
         -> {
           @lu.solve(values)
-        }.should raise_error(Matrix::ErrDimensionMismatch)
+        }.should.raise(Matrix::ErrDimensionMismatch)
       end
 
       it "returns the right vector when given a vector of the appropriate size" do
@@ -46,7 +46,7 @@ describe "Matrix::LUPDecomposition#solve" do
         values = Vector[14, 55]
         -> {
           @lu.solve(values)
-        }.should raise_error(Matrix::ErrDimensionMismatch)
+        }.should.raise(Matrix::ErrDimensionMismatch)
       end
     end
   end
diff --git a/spec/ruby/library/matrix/lup_decomposition/to_a_spec.rb b/spec/ruby/library/matrix/lup_decomposition/to_a_spec.rb
index 9b1dccbbac..ab59677dd9 100644
--- a/spec/ruby/library/matrix/lup_decomposition/to_a_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/to_a_spec.rb
@@ -10,9 +10,9 @@ describe "Matrix::LUPDecomposition#to_a" do
   end
 
   it "returns an array of three matrices" do
-    @to_a.should be_kind_of(Array)
+    @to_a.should.is_a?(Array)
     @to_a.length.should == 3
-    @to_a.each{|m| m.should be_kind_of(Matrix)}
+    @to_a.each{|m| m.should.is_a?(Matrix)}
   end
 
   it "returns [l, u, p] such that l*u == a*p" do
diff --git a/spec/ruby/library/matrix/lup_decomposition/u_spec.rb b/spec/ruby/library/matrix/lup_decomposition/u_spec.rb
index ca3dfc1f00..967bc669dc 100644
--- a/spec/ruby/library/matrix/lup_decomposition/u_spec.rb
+++ b/spec/ruby/library/matrix/lup_decomposition/u_spec.rb
@@ -13,6 +13,6 @@ describe "Matrix::LUPDecomposition#u" do
   end
 
   it "returns an upper triangular matrix" do
-    @u.upper_triangular?.should be_true
+    @u.upper_triangular?.should == true
   end
 end
diff --git a/spec/ruby/library/matrix/minor_spec.rb b/spec/ruby/library/matrix/minor_spec.rb
index 009826c3d6..6b29db568b 100644
--- a/spec/ruby/library/matrix/minor_spec.rb
+++ b/spec/ruby/library/matrix/minor_spec.rb
@@ -79,7 +79,7 @@ describe "Matrix#minor" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.minor(0, 1, 0, 1).should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.minor(0, 1, 0, 1).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/minus_spec.rb b/spec/ruby/library/matrix/minus_spec.rb
index 95cf4a6072..7426aa2d2c 100644
--- a/spec/ruby/library/matrix/minus_spec.rb
+++ b/spec/ruby/library/matrix/minus_spec.rb
@@ -13,30 +13,30 @@ describe "Matrix#-" do
   end
 
   it "returns an instance of Matrix" do
-    (@a - @b).should be_kind_of(Matrix)
+    (@a - @b).should.is_a?(Matrix)
   end
 
   it "raises a Matrix::ErrDimensionMismatch if the matrices are different sizes" do
-    -> { @a - Matrix[ [1] ] }.should raise_error(Matrix::ErrDimensionMismatch)
+    -> { @a - Matrix[ [1] ] }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "raises a ExceptionForMatrix::ErrOperationNotDefined if other is a Numeric Type" do
-    -> { @a - 2            }.should raise_error(Matrix::ErrOperationNotDefined)
-    -> { @a - 1.2          }.should raise_error(Matrix::ErrOperationNotDefined)
-    -> { @a - bignum_value }.should raise_error(Matrix::ErrOperationNotDefined)
+    -> { @a - 2            }.should.raise(Matrix::ErrOperationNotDefined)
+    -> { @a - 1.2          }.should.raise(Matrix::ErrOperationNotDefined)
+    -> { @a - bignum_value }.should.raise(Matrix::ErrOperationNotDefined)
   end
 
   it "raises a TypeError if other is of wrong type" do
-    -> { @a - nil        }.should raise_error(TypeError)
-    -> { @a - "a"        }.should raise_error(TypeError)
-    -> { @a - [ [1, 2] ] }.should raise_error(TypeError)
-    -> { @a - Object.new }.should raise_error(TypeError)
+    -> { @a - nil        }.should.raise(TypeError)
+    -> { @a - "a"        }.should.raise(TypeError)
+    -> { @a - [ [1, 2] ] }.should.raise(TypeError)
+    -> { @a - Object.new }.should.raise(TypeError)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
       m = MatrixSub.ins
-      (m-m).should be_an_instance_of(MatrixSub)
+      (m-m).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/multiply_spec.rb b/spec/ruby/library/matrix/multiply_spec.rb
index 585f268931..6c495c5521 100644
--- a/spec/ruby/library/matrix/multiply_spec.rb
+++ b/spec/ruby/library/matrix/multiply_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+
 require_relative 'fixtures/classes'
 require 'matrix'
 
@@ -22,8 +23,8 @@ describe "Matrix#*" do
 
   it "returns the result of multiplying the elements of self and a Bignum" do
     (@a * bignum_value).should == Matrix[
-      [9223372036854775808, 18446744073709551616],
-      [27670116110564327424, 36893488147419103232]
+      [18446744073709551616, 36893488147419103232],
+      [55340232221128654848, 73786976294838206464]
     ]
   end
 
@@ -32,7 +33,7 @@ describe "Matrix#*" do
   end
 
   it "raises a Matrix::ErrDimensionMismatch if the matrices are different sizes" do
-    -> { @a * Matrix[ [1] ] }.should raise_error(Matrix::ErrDimensionMismatch)
+    -> { @a * Matrix[ [1] ] }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "returns a zero matrix if (nx0) * (0xn)" do
@@ -52,17 +53,17 @@ describe "Matrix#*" do
   end
 
   it "raises a TypeError if other is of wrong type" do
-    -> { @a * nil        }.should raise_error(TypeError)
-    -> { @a * "a"        }.should raise_error(TypeError)
-    -> { @a * [ [1, 2] ] }.should raise_error(TypeError)
-    -> { @a * Object.new }.should raise_error(TypeError)
+    -> { @a * nil        }.should.raise(TypeError)
+    -> { @a * "a"        }.should.raise(TypeError)
+    -> { @a * [ [1, 2] ] }.should.raise(TypeError)
+    -> { @a * Object.new }.should.raise(TypeError)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
       m = MatrixSub.ins
-      (m*m).should be_an_instance_of(MatrixSub)
-      (m*1).should be_an_instance_of(MatrixSub)
+      (m*m).should.instance_of?(MatrixSub)
+      (m*1).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/new_spec.rb b/spec/ruby/library/matrix/new_spec.rb
index 3005066846..bde9d9f4c8 100644
--- a/spec/ruby/library/matrix/new_spec.rb
+++ b/spec/ruby/library/matrix/new_spec.rb
@@ -3,6 +3,6 @@ require 'matrix'
 
 describe "Matrix.new" do
   it "is private" do
-    Matrix.should have_private_method(:new)
+    Matrix.private_methods(false).should.include?(:new)
   end
 end
diff --git a/spec/ruby/library/matrix/normal_spec.rb b/spec/ruby/library/matrix/normal_spec.rb
index ebd73aaf40..420d4b011f 100644
--- a/spec/ruby/library/matrix/normal_spec.rb
+++ b/spec/ruby/library/matrix/normal_spec.rb
@@ -3,12 +3,12 @@ require 'matrix'
 
 describe "Matrix.normal?" do
   # it "returns false for non normal matrices" do
-  #   Matrix[[0, 1], [1, 2]].normal?.should == false
+  #   Matrix[[0, 1], [1, 2]].should_not.normal?
   # end
 
   it "returns true for normal matrices" do
-    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].normal?.should == true
-    Matrix[[0, Complex(0, 2)], [Complex(0, -2), 0]].normal?.should == true
+    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].should.normal?
+    Matrix[[0, Complex(0, 2)], [Complex(0, -2), 0]].should.normal?
   end
 
   it "raises an error for rectangular matrices" do
@@ -20,7 +20,7 @@ describe "Matrix.normal?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.normal?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/orthogonal_spec.rb b/spec/ruby/library/matrix/orthogonal_spec.rb
index 07b098a58d..71ac831fe8 100644
--- a/spec/ruby/library/matrix/orthogonal_spec.rb
+++ b/spec/ruby/library/matrix/orthogonal_spec.rb
@@ -3,12 +3,12 @@ require 'matrix'
 
 describe "Matrix.orthogonal?" do
   it "returns false for non orthogonal matrices" do
-    Matrix[[0, 1], [1, 2]].orthogonal?.should == false
-    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].orthogonal?.should == false
+    Matrix[[0, 1], [1, 2]].should_not.orthogonal?
+    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].should_not.orthogonal?
   end
 
   it "returns true for orthogonal matrices" do
-    Matrix[[0, 1], [1, 0]].orthogonal?.should == true
+    Matrix[[0, 1], [1, 0]].should.orthogonal?
   end
 
   it "raises an error for rectangular matrices" do
@@ -20,7 +20,7 @@ describe "Matrix.orthogonal?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.orthogonal?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/permutation_spec.rb b/spec/ruby/library/matrix/permutation_spec.rb
index 825a9d982c..43727edea1 100644
--- a/spec/ruby/library/matrix/permutation_spec.rb
+++ b/spec/ruby/library/matrix/permutation_spec.rb
@@ -3,18 +3,18 @@ require 'matrix'
 
 describe "Matrix#permutation?" do
   it "returns true for a permutation Matrix" do
-    Matrix[[0, 1, 0], [0, 0, 1], [1, 0, 0]].permutation?.should be_true
+    Matrix[[0, 1, 0], [0, 0, 1], [1, 0, 0]].permutation?.should == true
   end
 
   it "returns false for a non permutation square Matrix" do
-    Matrix[[0, 1], [0, 0]].permutation?.should be_false
-    Matrix[[-1, 0], [0, -1]].permutation?.should be_false
-    Matrix[[1, 0], [1, 0]].permutation?.should be_false
-    Matrix[[1, 0], [1, 1]].permutation?.should be_false
+    Matrix[[0, 1], [0, 0]].permutation?.should == false
+    Matrix[[-1, 0], [0, -1]].permutation?.should == false
+    Matrix[[1, 0], [1, 0]].permutation?.should == false
+    Matrix[[1, 0], [1, 1]].permutation?.should == false
   end
 
   it "returns true for an empty 0x0 matrix" do
-    Matrix.empty(0,0).permutation?.should be_true
+    Matrix.empty(0,0).permutation?.should == true
   end
 
   it "raises an error for rectangular matrices" do
@@ -26,7 +26,7 @@ describe "Matrix#permutation?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.permutation?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/plus_spec.rb b/spec/ruby/library/matrix/plus_spec.rb
index 2706bad060..72a9ba8f8f 100644
--- a/spec/ruby/library/matrix/plus_spec.rb
+++ b/spec/ruby/library/matrix/plus_spec.rb
@@ -13,30 +13,30 @@ describe "Matrix#+" do
   end
 
   it "returns an instance of Matrix" do
-    (@a + @b).should be_kind_of(Matrix)
+    (@a + @b).should.is_a?(Matrix)
   end
 
   it "raises a Matrix::ErrDimensionMismatch if the matrices are different sizes" do
-    -> { @a + Matrix[ [1] ] }.should raise_error(Matrix::ErrDimensionMismatch)
+    -> { @a + Matrix[ [1] ] }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   it "raises a ExceptionForMatrix::ErrOperationNotDefined if other is a Numeric Type" do
-    -> { @a + 2            }.should raise_error(ExceptionForMatrix::ErrOperationNotDefined)
-    -> { @a + 1.2          }.should raise_error(ExceptionForMatrix::ErrOperationNotDefined)
-    -> { @a + bignum_value }.should raise_error(ExceptionForMatrix::ErrOperationNotDefined)
+    -> { @a + 2            }.should.raise(ExceptionForMatrix::ErrOperationNotDefined)
+    -> { @a + 1.2          }.should.raise(ExceptionForMatrix::ErrOperationNotDefined)
+    -> { @a + bignum_value }.should.raise(ExceptionForMatrix::ErrOperationNotDefined)
   end
 
   it "raises a TypeError if other is of wrong type" do
-    -> { @a + nil        }.should raise_error(TypeError)
-    -> { @a + "a"        }.should raise_error(TypeError)
-    -> { @a + [ [1, 2] ] }.should raise_error(TypeError)
-    -> { @a + Object.new }.should raise_error(TypeError)
+    -> { @a + nil        }.should.raise(TypeError)
+    -> { @a + "a"        }.should.raise(TypeError)
+    -> { @a + [ [1, 2] ] }.should.raise(TypeError)
+    -> { @a + Object.new }.should.raise(TypeError)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
       m = MatrixSub.ins
-      (m+m).should be_an_instance_of(MatrixSub)
+      (m+m).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/real_spec.rb b/spec/ruby/library/matrix/real_spec.rb
index 38033c63c8..4589dc22a5 100644
--- a/spec/ruby/library/matrix/real_spec.rb
+++ b/spec/ruby/library/matrix/real_spec.rb
@@ -4,22 +4,22 @@ require 'matrix'
 
 describe "Matrix#real?" do
   it "returns true for matrices with all real entries" do
-    Matrix[ [1,   2], [3, 4] ].real?.should be_true
-    Matrix[ [1.9, 2], [3, 4] ].real?.should be_true
+    Matrix[ [1,   2], [3, 4] ].real?.should == true
+    Matrix[ [1.9, 2], [3, 4] ].real?.should == true
   end
 
   it "returns true for empty matrices" do
-    Matrix.empty.real?.should be_true
+    Matrix.empty.real?.should == true
   end
 
   it "returns false if one element is a Complex" do
-    Matrix[ [Complex(1,1), 2], [3, 4] ].real?.should be_false
+    Matrix[ [Complex(1,1), 2], [3, 4] ].real?.should == false
   end
 
   # Guard against the Mathn library
   guard -> { !defined?(Math.rsqrt) } do
     it "returns false if one element is a Complex whose imaginary part is 0" do
-      Matrix[ [Complex(1,0), 2], [3, 4] ].real?.should be_false
+      Matrix[ [Complex(1,0), 2], [3, 4] ].real?.should == false
     end
   end
 end
@@ -37,7 +37,7 @@ describe "Matrix#real" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.real.should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.real.should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/regular_spec.rb b/spec/ruby/library/matrix/regular_spec.rb
index 3699d0ef8b..4cb00819ac 100644
--- a/spec/ruby/library/matrix/regular_spec.rb
+++ b/spec/ruby/library/matrix/regular_spec.rb
@@ -5,27 +5,27 @@ describe "Matrix#regular?" do
 
   it "returns false for singular matrices" do
     m = Matrix[ [1,2,3], [3,4,3], [0,0,0] ]
-    m.regular?.should be_false
+    m.regular?.should == false
 
     m = Matrix[ [1,2,9], [3,4,9], [1,2,9] ]
-    m.regular?.should be_false
+    m.regular?.should == false
   end
 
   it "returns true if the Matrix is regular" do
-    Matrix[ [0,1], [1,0] ].regular?.should be_true
+    Matrix[ [0,1], [1,0] ].regular?.should == true
   end
 
   it "returns true for an empty 0x0 matrix" do
-    Matrix.empty(0,0).regular?.should be_true
+    Matrix.empty(0,0).regular?.should == true
   end
 
   it "raises an error for rectangular matrices" do
     -> {
       Matrix[[1], [2], [3]].regular?
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
 
     -> {
       Matrix.empty(3,0).regular?
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
   end
 end
diff --git a/spec/ruby/library/matrix/round_spec.rb b/spec/ruby/library/matrix/round_spec.rb
index 1dc29df890..cdec646fa1 100644
--- a/spec/ruby/library/matrix/round_spec.rb
+++ b/spec/ruby/library/matrix/round_spec.rb
@@ -15,7 +15,7 @@ describe "Matrix#round" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.round.should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.round.should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/row_spec.rb b/spec/ruby/library/matrix/row_spec.rb
index 00b1f02a8e..8a7662fdf2 100644
--- a/spec/ruby/library/matrix/row_spec.rb
+++ b/spec/ruby/library/matrix/row_spec.rb
@@ -21,7 +21,7 @@ describe "Matrix#row" do
   end
 
   it "returns self when called with a block" do
-    @m.row(0) { |x| x }.should equal(@m)
+    @m.row(0) { |x| x }.should.equal?(@m)
   end
 
   it "returns nil when out of bounds" do
@@ -30,7 +30,7 @@ describe "Matrix#row" do
   end
 
   it "never yields when out of bounds" do
-    -> { @m.row(3){ raise } }.should_not raise_error
-    -> { @m.row(-4){ raise } }.should_not raise_error
+    -> { @m.row(3){ raise } }.should_not.raise
+    -> { @m.row(-4){ raise } }.should_not.raise
   end
 end
diff --git a/spec/ruby/library/matrix/row_vector_spec.rb b/spec/ruby/library/matrix/row_vector_spec.rb
index 341437ee05..f3919fb7d8 100644
--- a/spec/ruby/library/matrix/row_vector_spec.rb
+++ b/spec/ruby/library/matrix/row_vector_spec.rb
@@ -5,7 +5,7 @@ require 'matrix'
 describe "Matrix.row_vector" do
 
   it "returns a Matrix" do
-    Matrix.row_vector([]).should be_an_instance_of(Matrix)
+    Matrix.row_vector([]).should.instance_of?(Matrix)
   end
 
   it "returns a single-row Matrix with the specified values" do
@@ -18,7 +18,7 @@ describe "Matrix.row_vector" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.row_vector([1]).should be_an_instance_of(MatrixSub)
+      MatrixSub.row_vector([1]).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/row_vectors_spec.rb b/spec/ruby/library/matrix/row_vectors_spec.rb
index 6f99c439a6..4a0db67527 100644
--- a/spec/ruby/library/matrix/row_vectors_spec.rb
+++ b/spec/ruby/library/matrix/row_vectors_spec.rb
@@ -8,11 +8,11 @@ describe "Matrix#row_vectors" do
   end
 
   it "returns an Array" do
-    Matrix[ [1,2], [3,4] ].row_vectors.should be_an_instance_of(Array)
+    Matrix[ [1,2], [3,4] ].row_vectors.should.instance_of?(Array)
   end
 
   it "returns an Array of Vectors" do
-    @vectors.all? {|v| v.should be_an_instance_of(Vector)}
+    @vectors.all? {|v| v.should.instance_of?(Vector)}
   end
 
   it "returns each row as a Vector" do
diff --git a/spec/ruby/library/matrix/rows_spec.rb b/spec/ruby/library/matrix/rows_spec.rb
index 41ba635775..9c248cd8a4 100644
--- a/spec/ruby/library/matrix/rows_spec.rb
+++ b/spec/ruby/library/matrix/rows_spec.rb
@@ -10,7 +10,7 @@ describe "Matrix.rows" do
   end
 
   it "returns a Matrix" do
-    @m.should be_kind_of(Matrix)
+    @m.should.is_a?(Matrix)
   end
 
   it "creates a matrix from argument rows" do
@@ -21,8 +21,8 @@ describe "Matrix.rows" do
   it "copies the original rows by default" do
     @a << 3
     @b << 6
-    @m.row(0).should_not equal(@a)
-    @m.row(1).should_not equal(@b)
+    @m.row(0).should_not.equal?(@a)
+    @m.row(1).should_not.equal?(@b)
   end
 
   it "references the original rows if copy is false" do
@@ -35,7 +35,7 @@ describe "Matrix.rows" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.rows([[0, 1], [0, 1]]).should be_an_instance_of(MatrixSub)
+      MatrixSub.rows([[0, 1], [0, 1]]).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/scalar_spec.rb b/spec/ruby/library/matrix/scalar_spec.rb
index 7fdd64c9d9..5b93b60533 100644
--- a/spec/ruby/library/matrix/scalar_spec.rb
+++ b/spec/ruby/library/matrix/scalar_spec.rb
@@ -10,7 +10,7 @@ describe "Matrix.scalar" do
   end
 
   it "returns a Matrix" do
-    @a.should be_kind_of(Matrix)
+    @a.should.is_a?(Matrix)
   end
 
   it "returns a n x n matrix" do
@@ -41,7 +41,7 @@ describe "Matrix.scalar" do
   end
 
   it "returns a Matrix" do
-    @a.should be_kind_of(Matrix)
+    @a.should.is_a?(Matrix)
   end
 
   it "returns a square matrix, where the first argument specifies the side of the square" do
diff --git a/spec/ruby/library/matrix/shared/collect.rb b/spec/ruby/library/matrix/shared/collect.rb
index 852f7fd6cf..3a4dbe3a36 100644
--- a/spec/ruby/library/matrix/shared/collect.rb
+++ b/spec/ruby/library/matrix/shared/collect.rb
@@ -7,7 +7,7 @@ describe :collect, shared: true do
   end
 
   it "returns an instance of Matrix" do
-    @m.send(@method){|n| n * 2 }.should be_kind_of(Matrix)
+    @m.send(@method){|n| n * 2 }.should.is_a?(Matrix)
   end
 
   it "returns a Matrix where each element is the result of the block" do
@@ -15,12 +15,12 @@ describe :collect, shared: true do
   end
 
   it "returns an enumerator if no block is given" do
-    @m.send(@method).should be_an_instance_of(Enumerator)
+    @m.send(@method).should.instance_of?(Enumerator)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.send(@method){1}.should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.send(@method){1}.should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/conjugate.rb b/spec/ruby/library/matrix/shared/conjugate.rb
index d87658f855..ffdf5ebca1 100644
--- a/spec/ruby/library/matrix/shared/conjugate.rb
+++ b/spec/ruby/library/matrix/shared/conjugate.rb
@@ -14,7 +14,7 @@ describe :matrix_conjugate, shared: true do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.send(@method).should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.send(@method).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/determinant.rb b/spec/ruby/library/matrix/shared/determinant.rb
index 9e0528c24b..b7c86393ba 100644
--- a/spec/ruby/library/matrix/shared/determinant.rb
+++ b/spec/ruby/library/matrix/shared/determinant.rb
@@ -29,10 +29,10 @@ describe :determinant, shared: true do
   it "raises an error for rectangular matrices" do
     -> {
       Matrix[[1], [2], [3]].send(@method)
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
 
     -> {
       Matrix.empty(3,0).send(@method)
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
   end
 end
diff --git a/spec/ruby/library/matrix/shared/equal_value.rb b/spec/ruby/library/matrix/shared/equal_value.rb
index 2b2311d49e..9bc6ed908b 100644
--- a/spec/ruby/library/matrix/shared/equal_value.rb
+++ b/spec/ruby/library/matrix/shared/equal_value.rb
@@ -7,27 +7,27 @@ describe :equal, shared: true do
   end
 
   it "returns true for self" do
-    @matrix.send(@method, @matrix).should be_true
+    @matrix.send(@method, @matrix).should == true
   end
 
   it "returns true for equal matrices" do
-    @matrix.send(@method, Matrix[ [1, 2, 3, 4, 5], [2, 3, 4, 5, 6] ]).should be_true
+    @matrix.send(@method, Matrix[ [1, 2, 3, 4, 5], [2, 3, 4, 5, 6] ]).should == true
   end
 
   it "returns false for different matrices" do
-    @matrix.send(@method, Matrix[ [42, 2, 3, 4, 5], [2, 3, 4, 5, 6] ]).should be_false
-    @matrix.send(@method, Matrix[ [1, 2, 3, 4, 5, 6], [2, 3, 4, 5, 6, 7] ]).should be_false
-    @matrix.send(@method, Matrix[ [1, 2, 3], [2, 3, 4] ]).should be_false
+    @matrix.send(@method, Matrix[ [42, 2, 3, 4, 5], [2, 3, 4, 5, 6] ]).should == false
+    @matrix.send(@method, Matrix[ [1, 2, 3, 4, 5, 6], [2, 3, 4, 5, 6, 7] ]).should == false
+    @matrix.send(@method, Matrix[ [1, 2, 3], [2, 3, 4] ]).should == false
   end
 
   it "returns false for different empty matrices" do
-    Matrix.empty(42, 0).send(@method, Matrix.empty(6, 0)).should be_false
-    Matrix.empty(0, 42).send(@method, Matrix.empty(0, 6)).should be_false
-    Matrix.empty(0, 0).send(@method, Matrix.empty(6, 0)).should be_false
-    Matrix.empty(0, 0).send(@method, Matrix.empty(0, 6)).should be_false
+    Matrix.empty(42, 0).send(@method, Matrix.empty(6, 0)).should == false
+    Matrix.empty(0, 42).send(@method, Matrix.empty(0, 6)).should == false
+    Matrix.empty(0, 0).send(@method, Matrix.empty(6, 0)).should == false
+    Matrix.empty(0, 0).send(@method, Matrix.empty(0, 6)).should == false
   end
 
   it "doesn't distinguish on subclasses" do
-    MatrixSub.ins.send(@method, Matrix.I(2)).should be_true
+    MatrixSub.ins.send(@method, Matrix.I(2)).should == true
   end
 end
diff --git a/spec/ruby/library/matrix/shared/identity.rb b/spec/ruby/library/matrix/shared/identity.rb
index 114f86e7b0..df957b5a75 100644
--- a/spec/ruby/library/matrix/shared/identity.rb
+++ b/spec/ruby/library/matrix/shared/identity.rb
@@ -3,7 +3,7 @@ require 'matrix'
 
 describe :matrix_identity, shared: true do
   it "returns a Matrix" do
-    Matrix.send(@method, 2).should be_kind_of(Matrix)
+    Matrix.send(@method, 2).should.is_a?(Matrix)
   end
 
   it "returns a n x n identity matrix" do
@@ -13,7 +13,7 @@ describe :matrix_identity, shared: true do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.send(@method, 2).should be_an_instance_of(MatrixSub)
+      MatrixSub.send(@method, 2).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/imaginary.rb b/spec/ruby/library/matrix/shared/imaginary.rb
index d28ecc69f1..16615213a2 100644
--- a/spec/ruby/library/matrix/shared/imaginary.rb
+++ b/spec/ruby/library/matrix/shared/imaginary.rb
@@ -14,7 +14,7 @@ describe :matrix_imaginary, shared: true do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.send(@method).should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.send(@method).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/inverse.rb b/spec/ruby/library/matrix/shared/inverse.rb
index c8a6b90da5..ac463cf680 100644
--- a/spec/ruby/library/matrix/shared/inverse.rb
+++ b/spec/ruby/library/matrix/shared/inverse.rb
@@ -4,7 +4,7 @@ require 'matrix'
 describe :inverse, shared: true do
 
   it "returns a Matrix" do
-    Matrix[ [1,2], [2,1] ].send(@method).should be_an_instance_of(Matrix)
+    Matrix[ [1,2], [2,1] ].send(@method).should.instance_of?(Matrix)
   end
 
   it "returns the inverse of the Matrix" do
@@ -27,12 +27,12 @@ describe :inverse, shared: true do
   it "raises a ErrDimensionMismatch if the Matrix is not square" do
     ->{
       Matrix[ [1,2,3], [1,2,3] ].send(@method)
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.send(@method).should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.send(@method).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/rectangular.rb b/spec/ruby/library/matrix/shared/rectangular.rb
index 3d9a0dfe8a..0229e614c6 100644
--- a/spec/ruby/library/matrix/shared/rectangular.rb
+++ b/spec/ruby/library/matrix/shared/rectangular.rb
@@ -12,7 +12,7 @@ describe :matrix_rectangular, shared: true do
 
   describe "for a subclass of Matrix" do
     it "returns instances of that subclass" do
-      MatrixSub.ins.send(@method).each{|m| m.should be_an_instance_of(MatrixSub) }
+      MatrixSub.ins.send(@method).each{|m| m.should.instance_of?(MatrixSub) }
     end
   end
 end
diff --git a/spec/ruby/library/matrix/shared/trace.rb b/spec/ruby/library/matrix/shared/trace.rb
index 57b89863f8..c4a5491b22 100644
--- a/spec/ruby/library/matrix/shared/trace.rb
+++ b/spec/ruby/library/matrix/shared/trace.rb
@@ -6,7 +6,7 @@ describe :trace, shared: true do
   end
 
   it "returns the sum of diagonal elements in a rectangular Matrix" do
-    ->{ Matrix[[1,2,3], [4,5,6]].trace}.should raise_error(Matrix::ErrDimensionMismatch)
+    ->{ Matrix[[1,2,3], [4,5,6]].trace}.should.raise(Matrix::ErrDimensionMismatch)
   end
 
 end
diff --git a/spec/ruby/library/matrix/shared/transpose.rb b/spec/ruby/library/matrix/shared/transpose.rb
index 89b1d025be..a0b495359b 100644
--- a/spec/ruby/library/matrix/shared/transpose.rb
+++ b/spec/ruby/library/matrix/shared/transpose.rb
@@ -13,7 +13,7 @@ describe :matrix_transpose, shared: true do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.ins.send(@method).should be_an_instance_of(MatrixSub)
+      MatrixSub.ins.send(@method).should.instance_of?(MatrixSub)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/singular_spec.rb b/spec/ruby/library/matrix/singular_spec.rb
index 7bba36a54a..00b93af495 100644
--- a/spec/ruby/library/matrix/singular_spec.rb
+++ b/spec/ruby/library/matrix/singular_spec.rb
@@ -4,28 +4,28 @@ require 'matrix'
 describe "Matrix#singular?" do
   it "returns true for singular matrices" do
     m = Matrix[ [1,2,3], [3,4,3], [0,0,0] ]
-    m.singular?.should be_true
+    m.singular?.should == true
 
     m = Matrix[ [1,2,9], [3,4,9], [1,2,9] ]
-    m.singular?.should be_true
+    m.singular?.should == true
   end
 
   it "returns false if the Matrix is regular" do
-    Matrix[ [0,1], [1,0] ].singular?.should be_false
+    Matrix[ [0,1], [1,0] ].singular?.should == false
   end
 
   it "returns false for an empty 0x0 matrix" do
-    Matrix.empty(0,0).singular?.should be_false
+    Matrix.empty(0,0).singular?.should == false
   end
 
   it "raises an error for rectangular matrices" do
     -> {
       Matrix[[1], [2], [3]].singular?
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
 
     -> {
       Matrix.empty(3,0).singular?
-    }.should raise_error(Matrix::ErrDimensionMismatch)
+    }.should.raise(Matrix::ErrDimensionMismatch)
   end
 
 end
diff --git a/spec/ruby/library/matrix/square_spec.rb b/spec/ruby/library/matrix/square_spec.rb
index 25d2d1ad9c..b8cf4acf44 100644
--- a/spec/ruby/library/matrix/square_spec.rb
+++ b/spec/ruby/library/matrix/square_spec.rb
@@ -4,25 +4,25 @@ require 'matrix'
 describe "Matrix#square?" do
 
   it "returns true when the Matrix is square" do
-    Matrix[ [1,2], [2,4] ].square?.should be_true
-    Matrix[ [100,3,5], [9.5, 4.9, 8], [2,0,77] ].square?.should be_true
+    Matrix[ [1,2], [2,4] ].square?.should == true
+    Matrix[ [100,3,5], [9.5, 4.9, 8], [2,0,77] ].square?.should == true
   end
 
   it "returns true when the Matrix has only one element" do
-    Matrix[ [9] ].square?.should be_true
+    Matrix[ [9] ].square?.should == true
   end
 
   it "returns false when the Matrix is rectangular" do
-    Matrix[ [1, 2] ].square?.should be_false
+    Matrix[ [1, 2] ].square?.should == false
   end
 
   it "returns false when the Matrix is rectangular" do
-    Matrix[ [1], [2] ].square?.should be_false
+    Matrix[ [1], [2] ].square?.should == false
   end
 
   it "returns handles empty matrices" do
-    Matrix[].square?.should be_true
-    Matrix[[]].square?.should be_false
-    Matrix.columns([[]]).square?.should be_false
+    Matrix[].square?.should == true
+    Matrix[[]].square?.should == false
+    Matrix.columns([[]]).square?.should == false
   end
 end
diff --git a/spec/ruby/library/matrix/symmetric_spec.rb b/spec/ruby/library/matrix/symmetric_spec.rb
index 6f2a99276a..4b86c19503 100644
--- a/spec/ruby/library/matrix/symmetric_spec.rb
+++ b/spec/ruby/library/matrix/symmetric_spec.rb
@@ -3,15 +3,15 @@ require 'matrix'
 
 describe "Matrix.symmetric?" do
   it "returns true for a symmetric Matrix" do
-    Matrix[[1, 2, Complex(0, 3)], [2, 4, 5], [Complex(0, 3), 5, 6]].symmetric?.should be_true
+    Matrix[[1, 2, Complex(0, 3)], [2, 4, 5], [Complex(0, 3), 5, 6]].symmetric?.should == true
   end
 
   it "returns true for a 0x0 empty matrix" do
-    Matrix.empty.symmetric?.should be_true
+    Matrix.empty.symmetric?.should == true
   end
 
   it "returns false for an asymmetric Matrix" do
-    Matrix[[1, 2],[-2, 1]].symmetric?.should be_false
+    Matrix[[1, 2],[-2, 1]].symmetric?.should == false
   end
 
   it "raises an error for rectangular matrices" do
@@ -23,7 +23,7 @@ describe "Matrix.symmetric?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.symmetric?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/unitary_spec.rb b/spec/ruby/library/matrix/unitary_spec.rb
index 9c2a106ea5..4490e8f8d4 100644
--- a/spec/ruby/library/matrix/unitary_spec.rb
+++ b/spec/ruby/library/matrix/unitary_spec.rb
@@ -1,16 +1,20 @@
 require_relative '../../spec_helper'
+
 require 'matrix'
 
 describe "Matrix.unitary?" do
   it "returns false for non unitary matrices" do
-    Matrix[[0, 1], [1, 2]].unitary?.should == false
-    Matrix[[0, Complex(0, 2)], [Complex(0, 2), 0]].unitary?.should == false
-    Matrix[[0, Complex(0, 1)], [Complex(0, -1), 0]].unitary?.should == false
-    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].unitary?.should == false
+    Matrix[[0, 1], [1, 2]].should_not.unitary?
+    Matrix[[0, Complex(0, 2)], [Complex(0, 2), 0]].should_not.unitary?
+    Matrix[[1, 1, 0], [0, 1, 1], [1, 0, 1]].should_not.unitary?
   end
 
   it "returns true for unitary matrices" do
-    Matrix[[0, Complex(0, 1)], [Complex(0, 1), 0]].unitary?.should == true
+    Matrix[[0, Complex(0, 1)], [Complex(0, 1), 0]].should.unitary?
+  end
+
+  it "returns true for unitary matrices with a Complex and a negative #imag" do
+    Matrix[[0, Complex(0, 1)], [Complex(0, -1), 0]].should.unitary?
   end
 
   it "raises an error for rectangular matrices" do
@@ -22,7 +26,7 @@ describe "Matrix.unitary?" do
     ].each do |rectangular_matrix|
       -> {
         rectangular_matrix.unitary?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+      }.should.raise(Matrix::ErrDimensionMismatch)
     end
   end
 end
diff --git a/spec/ruby/library/matrix/upper_triangular_spec.rb b/spec/ruby/library/matrix/upper_triangular_spec.rb
index 2514294a80..0e2bf611e2 100644
--- a/spec/ruby/library/matrix/upper_triangular_spec.rb
+++ b/spec/ruby/library/matrix/upper_triangular_spec.rb
@@ -3,22 +3,22 @@ require 'matrix'
 
 describe "Matrix.upper_triangular?" do
   it "returns true for an upper triangular Matrix" do
-    Matrix[[1, 2, 3], [0, 2, 3], [0, 0, 3]].upper_triangular?.should be_true
-    Matrix.diagonal([1, 2, 3]).upper_triangular?.should be_true
-    Matrix[[1, 2], [0, 2], [0, 0], [0, 0]].upper_triangular?.should be_true
-    Matrix[[1, 2, 3, 4], [0, 2, 3, 4]].upper_triangular?.should be_true
+    Matrix[[1, 2, 3], [0, 2, 3], [0, 0, 3]].upper_triangular?.should == true
+    Matrix.diagonal([1, 2, 3]).upper_triangular?.should == true
+    Matrix[[1, 2], [0, 2], [0, 0], [0, 0]].upper_triangular?.should == true
+    Matrix[[1, 2, 3, 4], [0, 2, 3, 4]].upper_triangular?.should == true
   end
 
   it "returns false for a non upper triangular square Matrix" do
-    Matrix[[0, 0], [1, 0]].upper_triangular?.should be_false
-    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].upper_triangular?.should be_false
-    Matrix[[0, 0], [0, 0], [0, 0], [0, 1]].upper_triangular?.should be_false
-    Matrix[[0, 0, 0, 0], [1, 0, 0, 0]].upper_triangular?.should be_false
+    Matrix[[0, 0], [1, 0]].upper_triangular?.should == false
+    Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].upper_triangular?.should == false
+    Matrix[[0, 0], [0, 0], [0, 0], [0, 1]].upper_triangular?.should == false
+    Matrix[[0, 0, 0, 0], [1, 0, 0, 0]].upper_triangular?.should == false
   end
 
   it "returns true for an empty matrix" do
-    Matrix.empty(3,0).upper_triangular?.should be_true
-    Matrix.empty(0,3).upper_triangular?.should be_true
-    Matrix.empty(0,0).upper_triangular?.should be_true
+    Matrix.empty(3,0).upper_triangular?.should == true
+    Matrix.empty(0,3).upper_triangular?.should == true
+    Matrix.empty(0,0).upper_triangular?.should == true
   end
 end
diff --git a/spec/ruby/library/matrix/vector/cross_product_spec.rb b/spec/ruby/library/matrix/vector/cross_product_spec.rb
index c2698ade4c..96a462c067 100644
--- a/spec/ruby/library/matrix/vector/cross_product_spec.rb
+++ b/spec/ruby/library/matrix/vector/cross_product_spec.rb
@@ -9,6 +9,6 @@ describe "Vector#cross_product" do
   it "raises an error unless both vectors have dimension 3" do
     -> {
       Vector[1, 2, 3].cross_product(Vector[0, -4])
-    }.should raise_error(Vector::ErrDimensionMismatch)
+    }.should.raise(Vector::ErrDimensionMismatch)
   end
 end
diff --git a/spec/ruby/library/matrix/vector/each2_spec.rb b/spec/ruby/library/matrix/vector/each2_spec.rb
index 10d2fc404d..86e7ed75aa 100644
--- a/spec/ruby/library/matrix/vector/each2_spec.rb
+++ b/spec/ruby/library/matrix/vector/each2_spec.rb
@@ -8,8 +8,8 @@ describe "Vector.each2" do
   end
 
   it "requires one argument" do
-    -> { @v.each2(@v2, @v2){} }.should raise_error(ArgumentError)
-    -> { @v.each2(){} }.should raise_error(ArgumentError)
+    -> { @v.each2(@v2, @v2){} }.should.raise(ArgumentError)
+    -> { @v.each2(){} }.should.raise(ArgumentError)
   end
 
   describe "given one argument" do
@@ -20,8 +20,8 @@ describe "Vector.each2" do
     end
 
     it "raises a DimensionMismatch error if the Vector size is different" do
-      -> { @v.each2(Vector[1,2]){}     }.should raise_error(Vector::ErrDimensionMismatch)
-      -> { @v.each2(Vector[1,2,3,4]){} }.should raise_error(Vector::ErrDimensionMismatch)
+      -> { @v.each2(Vector[1,2]){}     }.should.raise(Vector::ErrDimensionMismatch)
+      -> { @v.each2(Vector[1,2,3,4]){} }.should.raise(Vector::ErrDimensionMismatch)
     end
 
     it "yields arguments in sequence" do
@@ -37,12 +37,12 @@ describe "Vector.each2" do
     end
 
     it "returns self when given a block" do
-      @v.each2(@v2){}.should equal(@v)
+      @v.each2(@v2){}.should.equal?(@v)
     end
 
     it "returns an enumerator if no block given" do
       enum = @v.each2(@v2)
-      enum.should be_an_instance_of(Enumerator)
+      enum.should.instance_of?(Enumerator)
       enum.to_a.should == [[1, 4], [2, 5], [3, 6]]
     end
   end
diff --git a/spec/ruby/library/matrix/vector/eql_spec.rb b/spec/ruby/library/matrix/vector/eql_spec.rb
index eb2451b550..6e2cd47b8e 100644
--- a/spec/ruby/library/matrix/vector/eql_spec.rb
+++ b/spec/ruby/library/matrix/vector/eql_spec.rb
@@ -7,10 +7,10 @@ describe "Vector#eql?" do
   end
 
   it "returns true for self" do
-    @vector.eql?(@vector).should be_true
+    @vector.eql?(@vector).should == true
   end
 
   it "returns false when there are a pair corresponding elements which are not equal in the sense of Kernel#eql?" do
-    @vector.eql?(Vector[1, 2, 3, 4, 5.0]).should be_false
+    @vector.eql?(Vector[1, 2, 3, 4, 5.0]).should == false
   end
 end
diff --git a/spec/ruby/library/matrix/vector/inner_product_spec.rb b/spec/ruby/library/matrix/vector/inner_product_spec.rb
index 1cf8771e04..79dee10833 100644
--- a/spec/ruby/library/matrix/vector/inner_product_spec.rb
+++ b/spec/ruby/library/matrix/vector/inner_product_spec.rb
@@ -13,7 +13,7 @@ describe "Vector#inner_product" do
   it "raises an error for mismatched vectors" do
     -> {
       Vector[1, 2, 3].inner_product(Vector[0, -4])
-    }.should raise_error(Vector::ErrDimensionMismatch)
+    }.should.raise(Vector::ErrDimensionMismatch)
   end
 
   it "uses the conjugate of its argument" do
diff --git a/spec/ruby/library/matrix/vector/normalize_spec.rb b/spec/ruby/library/matrix/vector/normalize_spec.rb
index 527c9260de..bb1f046786 100644
--- a/spec/ruby/library/matrix/vector/normalize_spec.rb
+++ b/spec/ruby/library/matrix/vector/normalize_spec.rb
@@ -10,9 +10,9 @@ describe "Vector#normalize" do
   it "raises an error for zero vectors" do
     -> {
       Vector[].normalize
-    }.should raise_error(Vector::ZeroVectorError)
+    }.should.raise(Vector::ZeroVectorError)
     -> {
       Vector[0, 0, 0].normalize
-    }.should raise_error(Vector::ZeroVectorError)
+    }.should.raise(Vector::ZeroVectorError)
   end
 end
diff --git a/spec/ruby/library/matrix/zero_spec.rb b/spec/ruby/library/matrix/zero_spec.rb
index 643c57acba..406bcad6ed 100644
--- a/spec/ruby/library/matrix/zero_spec.rb
+++ b/spec/ruby/library/matrix/zero_spec.rb
@@ -4,7 +4,7 @@ require 'matrix'
 
 describe "Matrix.zero" do
   it "returns an object of type Matrix" do
-    Matrix.zero(3).should be_kind_of(Matrix)
+    Matrix.zero(3).should.is_a?(Matrix)
   end
 
   it "creates a n x n matrix" do
@@ -30,23 +30,23 @@ describe "Matrix.zero" do
 
   describe "for a subclass of Matrix" do
     it "returns an instance of that subclass" do
-      MatrixSub.zero(3).should be_an_instance_of(MatrixSub)
+      MatrixSub.zero(3).should.instance_of?(MatrixSub)
     end
   end
 end
 
 describe "Matrix.zero?" do
   it "returns true for empty matrices" do
-    Matrix.empty.zero?.should == true
-    Matrix.empty(3,0).zero?.should == true
-    Matrix.empty(0,3).zero?.should == true
+    Matrix.empty.should.zero?
+    Matrix.empty(3,0).should.zero?
+    Matrix.empty(0,3).should.zero?
   end
 
   it "returns true for matrices with zero entries" do
-    Matrix.zero(2,3).zero?.should == true
+    Matrix.zero(2,3).should.zero?
   end
 
   it "returns false for matrices with non zero entries" do
-    Matrix[[1]].zero?.should == false
+    Matrix[[1]].should_not.zero?
   end
 end
diff --git a/spec/ruby/library/mkmf/mkmf_spec.rb b/spec/ruby/library/mkmf/mkmf_spec.rb
new file mode 100644
index 0000000000..18b090e703
--- /dev/null
+++ b/spec/ruby/library/mkmf/mkmf_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../spec_helper'
+
+describe 'mkmf' do
+  it 'can be required with --enable-frozen-string-literal' do
+    ruby_exe('p MakeMakefile', options: '-rmkmf --enable-frozen-string-literal').should == "MakeMakefile\n"
+  end
+end
diff --git a/spec/ruby/library/monitor/enter_spec.rb b/spec/ruby/library/monitor/enter_spec.rb
new file mode 100644
index 0000000000..f523c42087
--- /dev/null
+++ b/spec/ruby/library/monitor/enter_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#enter" do
+  it "acquires the monitor" do
+    monitor = Monitor.new
+    10.times do
+      wait_q = Queue.new
+      continue_q = Queue.new
+
+      thread = Thread.new do
+        begin
+          monitor.enter
+          wait_q << true
+          continue_q.pop
+        ensure
+          monitor.exit
+        end
+      end
+
+      wait_q.pop
+      monitor.mon_locked?.should == true
+      continue_q << true
+      thread.join
+      monitor.mon_locked?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/monitor/exit_spec.rb b/spec/ruby/library/monitor/exit_spec.rb
new file mode 100644
index 0000000000..0748a523ac
--- /dev/null
+++ b/spec/ruby/library/monitor/exit_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#exit" do
+  it "raises ThreadError when monitor is not entered" do
+    m = Monitor.new
+
+    -> { m.exit }.should.raise(ThreadError)
+  end
+end
diff --git a/spec/ruby/library/monitor/mon_initialize_spec.rb b/spec/ruby/library/monitor/mon_initialize_spec.rb
index e0fe6c2d97..092aee929c 100644
--- a/spec/ruby/library/monitor/mon_initialize_spec.rb
+++ b/spec/ruby/library/monitor/mon_initialize_spec.rb
@@ -26,6 +26,6 @@ describe "MonitorMixin#mon_initialize" do
 
     instance = cls.new(1, 2, 3)
     copy = instance.dup
-    copy.should_not equal(instance)
+    copy.should_not.equal?(instance)
   end
 end
diff --git a/spec/ruby/library/monitor/new_cond_spec.rb b/spec/ruby/library/monitor/new_cond_spec.rb
new file mode 100644
index 0000000000..ec25d3f8a2
--- /dev/null
+++ b/spec/ruby/library/monitor/new_cond_spec.rb
@@ -0,0 +1,88 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#new_cond" do
+  it "creates a MonitorMixin::ConditionVariable" do
+    m = Monitor.new
+    c = m.new_cond
+    c.class.should == MonitorMixin::ConditionVariable
+  end
+
+  it 'returns a condition variable which can be waited on by a thread holding the monitor' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          wait_q << true
+          c.wait
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      # Synchronize can't happen until the other thread is waiting.
+      m.synchronize { c.signal }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+  it 'returns a condition variable which can be waited on by a thread holding the monitor inside multiple synchronize blocks' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          m.synchronize do
+            wait_q << true
+            c.wait
+          end
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      #No need to wait here as we cannot synchronize until the other thread is waiting.
+      m.synchronize { c.signal }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+  it 'returns a condition variable which can be signalled by a thread holding the monitor inside multiple synchronize blocks' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          wait_q << true
+          c.wait
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      # Synchronize can't happen until the other thread is waiting.
+      m.synchronize { m.synchronize { c.signal } }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+end
diff --git a/spec/ruby/library/monitor/synchronize_spec.rb b/spec/ruby/library/monitor/synchronize_spec.rb
new file mode 100644
index 0000000000..27cc1258b4
--- /dev/null
+++ b/spec/ruby/library/monitor/synchronize_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#synchronize" do
+  it "unlocks after return, even if it was interrupted by Thread#raise" do
+    exc_class = Class.new(RuntimeError)
+
+    monitor = Monitor.new
+    10.times do
+      wait_q = Queue.new
+      continue_q = Queue.new
+
+      thread = Thread.new do
+        begin
+          monitor.synchronize do
+            wait_q << true
+            # Do not wait here, we are trying to interrupt the ensure part of #synchronize
+          end
+          continue_q.pop
+        rescue exc_class
+          monitor.should_not.mon_locked?
+          :ok
+        end
+      end
+
+      wait_q.pop
+      thread.raise exc_class, "interrupt"
+      continue_q << true
+      thread.value.should == :ok
+    end
+  end
+
+  it "raises a LocalJumpError if not passed a block" do
+    -> { Monitor.new.synchronize }.should.raise(LocalJumpError)
+  end
+
+  it "raises a thread error if the monitor is not owned on exiting the block" do
+    monitor = Monitor.new
+    -> { monitor.synchronize { monitor.exit } }.should.raise(ThreadError)
+  end
+end
diff --git a/spec/ruby/library/monitor/try_enter_spec.rb b/spec/ruby/library/monitor/try_enter_spec.rb
new file mode 100644
index 0000000000..04b878f720
--- /dev/null
+++ b/spec/ruby/library/monitor/try_enter_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#try_enter" do
+  it "will acquire a monitor not held by another thread" do
+    monitor = Monitor.new
+    10.times do
+
+      thread = Thread.new do
+        val = monitor.try_enter
+        monitor.exit if val
+        val
+      end
+
+      thread.join
+      thread.value.should == true
+    end
+  end
+
+  it "will not acquire a monitor already held by another thread" do
+    monitor = Monitor.new
+    10.times do
+      monitor.enter
+      begin
+        thread = Thread.new do
+          val = monitor.try_enter
+          monitor.exit if val
+          val
+        end
+
+        thread.join
+        thread.value.should == false
+      ensure
+        monitor.exit
+      end
+      monitor.mon_locked?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/FTPError_spec.rb b/spec/ruby/library/net-ftp/FTPError_spec.rb
new file mode 100644
index 0000000000..b447e50546
--- /dev/null
+++ b/spec/ruby/library/net-ftp/FTPError_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require 'net/ftp'
+
+  describe "Net::FTPError" do
+    it "is an Exception" do
+      Net::FTPError.should < Exception
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/FTPPermError_spec.rb b/spec/ruby/library/net-ftp/FTPPermError_spec.rb
new file mode 100644
index 0000000000..b9a2d93aef
--- /dev/null
+++ b/spec/ruby/library/net-ftp/FTPPermError_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require 'net/ftp'
+
+  describe "Net::FTPPermError" do
+    it "is an Exception" do
+      Net::FTPPermError.should < Exception
+    end
+
+    it "is a subclass of Net::FTPError" do
+      Net::FTPPermError.should < Net::FTPError
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/FTPProtoError_spec.rb b/spec/ruby/library/net-ftp/FTPProtoError_spec.rb
new file mode 100644
index 0000000000..a1d9e44d63
--- /dev/null
+++ b/spec/ruby/library/net-ftp/FTPProtoError_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require 'net/ftp'
+
+  describe "Net::FTPProtoError" do
+    it "is an Exception" do
+      Net::FTPProtoError.should < Exception
+    end
+
+    it "is a subclass of Net::FTPError" do
+      Net::FTPPermError.should < Net::FTPError
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/FTPReplyError_spec.rb b/spec/ruby/library/net-ftp/FTPReplyError_spec.rb
new file mode 100644
index 0000000000..c9e6468323
--- /dev/null
+++ b/spec/ruby/library/net-ftp/FTPReplyError_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require 'net/ftp'
+
+  describe "Net::FTPReplyError" do
+    it "is an Exception" do
+      Net::FTPReplyError.should < Exception
+    end
+
+    it "is a subclass of Net::FTPError" do
+      Net::FTPPermError.should < Net::FTPError
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/FTPTempError_spec.rb b/spec/ruby/library/net-ftp/FTPTempError_spec.rb
new file mode 100644
index 0000000000..c0953cb0f2
--- /dev/null
+++ b/spec/ruby/library/net-ftp/FTPTempError_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require 'net/ftp'
+
+  describe "Net::FTPTempError" do
+    it "is an Exception" do
+      Net::FTPTempError.should < Exception
+    end
+
+    it "is a subclass of Net::FTPError" do
+      Net::FTPPermError.should < Net::FTPError
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/abort_spec.rb b/spec/ruby/library/net-ftp/abort_spec.rb
new file mode 100644
index 0000000000..9e8be53c68
--- /dev/null
+++ b/spec/ruby/library/net-ftp/abort_spec.rb
@@ -0,0 +1,65 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#abort" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the ABOR command to the server" do
+      -> { @ftp.abort }.should_not.raise
+    end
+
+    it "ignores the response" do
+      @ftp.abort
+      @ftp.last_response.should == "220 Dummy FTP Server ready!\n"
+    end
+
+    it "returns the full response" do
+      @ftp.abort.should == "226 Closing data connection. (ABOR)\n"
+    end
+
+    it "does not raise any error when the response code is 225" do
+      @server.should_receive(:abor).and_respond("225 Data connection open; no transfer in progress.")
+      -> { @ftp.abort }.should_not.raise
+    end
+
+    it "does not raise any error when the response code is 226" do
+      @server.should_receive(:abor).and_respond("226 Closing data connection.")
+      -> { @ftp.abort }.should_not.raise
+    end
+
+    it "raises a Net::FTPProtoError when the response code is 500" do
+      @server.should_receive(:abor).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.abort }.should.raise(Net::FTPProtoError)
+    end
+
+    it "raises a Net::FTPProtoError when the response code is 501" do
+      @server.should_receive(:abor).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.abort }.should.raise(Net::FTPProtoError)
+    end
+
+    it "raises a Net::FTPProtoError when the response code is 502" do
+      @server.should_receive(:abor).and_respond("502 Command not implemented.")
+      -> { @ftp.abort }.should.raise(Net::FTPProtoError)
+    end
+
+    it "raises a Net::FTPProtoError when the response code is 421" do
+      @server.should_receive(:abor).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.abort }.should.raise(Net::FTPProtoError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/acct_spec.rb b/spec/ruby/library/net-ftp/acct_spec.rb
new file mode 100644
index 0000000000..a64a0f48a8
--- /dev/null
+++ b/spec/ruby/library/net-ftp/acct_spec.rb
@@ -0,0 +1,61 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#acct" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "writes the ACCT command to the server" do
+      @ftp.acct("my_account")
+      @ftp.last_response.should == "230 User 'my_account' logged in, proceed. (ACCT)\n"
+    end
+
+    it "returns nil" do
+      @ftp.acct("my_account").should == nil
+    end
+
+    it "does not raise any error when the response code is 230" do
+      @server.should_receive(:acct).and_respond("230 User logged in, proceed.")
+      -> { @ftp.acct("my_account") }.should_not.raise
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:acct).and_respond("530 Not logged in.")
+      -> { @ftp.acct("my_account") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:acct).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.acct("my_account") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:acct).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.acct("my_account") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 503" do
+      @server.should_receive(:acct).and_respond("503 Bad sequence of commands.")
+      -> { @ftp.acct("my_account") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:acct).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.acct("my_account") }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/binary_spec.rb b/spec/ruby/library/net-ftp/binary_spec.rb
new file mode 100644
index 0000000000..de8d0ac103
--- /dev/null
+++ b/spec/ruby/library/net-ftp/binary_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#binary" do
+    it "returns true when self is in binary mode" do
+      ftp = Net::FTP.new
+      ftp.binary.should == true
+
+      ftp.binary = false
+      ftp.binary.should == false
+    end
+  end
+
+  describe "Net::FTP#binary=" do
+    it "sets self to binary mode when passed true" do
+      ftp = Net::FTP.new
+
+      ftp.binary = true
+      ftp.binary.should == true
+
+      ftp.binary = false
+      ftp.binary.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/chdir_spec.rb b/spec/ruby/library/net-ftp/chdir_spec.rb
new file mode 100644
index 0000000000..f8f352158c
--- /dev/null
+++ b/spec/ruby/library/net-ftp/chdir_spec.rb
@@ -0,0 +1,102 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#chdir" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    describe "when switching to the parent directory" do
+      it "sends the 'CDUP' command to the server" do
+        @ftp.chdir("..")
+        @ftp.last_response.should == "200 Command okay. (CDUP)\n"
+      end
+
+      it "returns nil" do
+        @ftp.chdir("..").should == nil
+      end
+
+      it "does not raise a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:cdup).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.chdir("..") }.should_not.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:cdup).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.chdir("..") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:cdup).and_respond("502 Command not implemented.")
+        -> { @ftp.chdir("..") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:cdup).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.chdir("..") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:cdup).and_respond("530 Not logged in.")
+        -> { @ftp.chdir("..") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 550" do
+        @server.should_receive(:cdup).and_respond("550 Requested action not taken.")
+        -> { @ftp.chdir("..") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    it "writes the 'CWD' command with the passed directory to the socket" do
+      @ftp.chdir("test")
+      @ftp.last_response.should == "200 Command okay. (CWD test)\n"
+    end
+
+    it "returns nil" do
+      @ftp.chdir("test").should == nil
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:cwd).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:cwd).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:cwd).and_respond("502 Command not implemented.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:cwd).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:cwd).and_respond("530 Not logged in.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:cwd).and_respond("550 Requested action not taken.")
+      -> { @ftp.chdir("test") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/close_spec.rb b/spec/ruby/library/net-ftp/close_spec.rb
new file mode 100644
index 0000000000..9d5d4c638a
--- /dev/null
+++ b/spec/ruby/library/net-ftp/close_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#close" do
+    before :each do
+      @socket = mock("Socket")
+      @socket.stub!(:closed?).and_return(false)
+      @socket.stub!(:read_timeout).and_return(60)
+      @socket.stub!(:read_timeout=).and_return(3)
+
+      @ftp = Net::FTP.new
+      @ftp.instance_variable_set(:@sock, @socket)
+    end
+
+    it "closes the socket" do
+      @socket.should_receive(:close)
+      @ftp.close.should == nil
+    end
+
+    it "does not try to close the socket if it has already been closed" do
+      @socket.should_receive(:closed?).and_return(true)
+      @socket.should_not_receive(:close)
+      @ftp.close.should == nil
+    end
+
+    it "does not try to close the socket if it is nil" do
+      @ftp.instance_variable_set(:@sock, nil)
+      @ftp.close.should == nil
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/closed_spec.rb b/spec/ruby/library/net-ftp/closed_spec.rb
new file mode 100644
index 0000000000..1c8693932e
--- /dev/null
+++ b/spec/ruby/library/net-ftp/closed_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#closed?" do
+    before :each do
+      @socket = mock("Socket")
+
+      @ftp = Net::FTP.new
+      @ftp.instance_variable_set(:@sock, @socket)
+    end
+
+    it "returns true when the socket is closed" do
+      @socket.should_receive(:closed?).and_return(true)
+      @ftp.closed?.should == true
+    end
+
+    it "returns true when the socket is nil" do
+      @ftp.instance_variable_set(:@sock, nil)
+      @ftp.closed?.should == true
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/connect_spec.rb b/spec/ruby/library/net-ftp/connect_spec.rb
new file mode 100644
index 0000000000..597381f67c
--- /dev/null
+++ b/spec/ruby/library/net-ftp/connect_spec.rb
@@ -0,0 +1,46 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  # TODO: Add specs for using the SOCKSSocket
+  describe "Net::FTP#connect" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+    end
+
+    after :each do
+      @server.connect_message = nil
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "tries to connect to the FTP Server on the given host and port" do
+      -> { @ftp.connect(@server.hostname, @server.server_port) }.should_not.raise
+    end
+
+    it "returns nil" do
+      @ftp.connect(@server.hostname, @server.server_port).should == nil
+    end
+
+    it "does not raise any error when the response code is 220" do
+      @server.connect_message = "220 Dummy FTP Server ready!"
+      -> { @ftp.connect(@server.hostname, @server.server_port) }.should_not.raise
+    end
+
+    it "raises a Net::FTPReplyError when the response code is 120" do
+      @server.connect_message = "120 Service ready in nnn minutes."
+      -> { @ftp.connect(@server.hostname, @server.server_port) }.should.raise(Net::FTPReplyError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.connect_message = "421 Service not available, closing control connection."
+      -> { @ftp.connect(@server.hostname, @server.server_port) }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/debug_mode_spec.rb b/spec/ruby/library/net-ftp/debug_mode_spec.rb
new file mode 100644
index 0000000000..28765b9d1c
--- /dev/null
+++ b/spec/ruby/library/net-ftp/debug_mode_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#debug_mode" do
+    it "returns true when self is in debug mode" do
+      ftp = Net::FTP.new
+      ftp.debug_mode.should == false
+
+      ftp.debug_mode = true
+      ftp.debug_mode.should == true
+    end
+  end
+
+  describe "Net::FTP#debug_mode=" do
+    it "sets self into debug mode when passed true" do
+      ftp = Net::FTP.new
+      ftp.debug_mode = true
+      ftp.debug_mode.should == true
+
+      ftp.debug_mode = false
+      ftp.debug_mode.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/default_passive_spec.rb b/spec/ruby/library/net-ftp/default_passive_spec.rb
new file mode 100644
index 0000000000..b47b4e9782
--- /dev/null
+++ b/spec/ruby/library/net-ftp/default_passive_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#default_passive" do
+    it "is true by default" do
+      ruby_exe(fixture(__FILE__, "default_passive.rb")).should == "true\ntrue\n"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/delete_spec.rb b/spec/ruby/library/net-ftp/delete_spec.rb
new file mode 100644
index 0000000000..40cd8f1d99
--- /dev/null
+++ b/spec/ruby/library/net-ftp/delete_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#delete" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the DELE command with the passed filename to the server" do
+      @ftp.delete("test.file")
+      @ftp.last_response.should == "250 Requested file action okay, completed. (DELE test.file)\n"
+    end
+
+    it "raises a Net::FTPTempError when the response code is 450" do
+      @server.should_receive(:dele).and_respond("450 Requested file action not taken.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:dele).and_respond("550 Requested action not taken.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:dele).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:dele).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:dele).and_respond("502 Command not implemented.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:dele).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:dele).and_respond("530 Not logged in.")
+      -> { @ftp.delete("test.file") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/dir_spec.rb b/spec/ruby/library/net-ftp/dir_spec.rb
new file mode 100644
index 0000000000..af38724fad
--- /dev/null
+++ b/spec/ruby/library/net-ftp/dir_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/list'
+
+  describe "Net::FTP#dir" do
+    it_behaves_like :net_ftp_list, :dir
+  end
+end
diff --git a/spec/ruby/library/net/ftp/fixtures/default_passive.rb b/spec/ruby/library/net-ftp/fixtures/default_passive.rb
index b6995d6f34..b6995d6f34 100644
--- a/spec/ruby/library/net/ftp/fixtures/default_passive.rb
+++ b/spec/ruby/library/net-ftp/fixtures/default_passive.rb
diff --git a/spec/ruby/library/net/ftp/fixtures/passive.rb b/spec/ruby/library/net-ftp/fixtures/passive.rb
index 6b5cde82df..6b5cde82df 100644
--- a/spec/ruby/library/net/ftp/fixtures/passive.rb
+++ b/spec/ruby/library/net-ftp/fixtures/passive.rb
diff --git a/spec/ruby/library/net/ftp/fixtures/putbinaryfile b/spec/ruby/library/net-ftp/fixtures/putbinaryfile
index f3130c6e43..f3130c6e43 100644
--- a/spec/ruby/library/net/ftp/fixtures/putbinaryfile
+++ b/spec/ruby/library/net-ftp/fixtures/putbinaryfile
diff --git a/spec/ruby/library/net/ftp/fixtures/puttextfile b/spec/ruby/library/net-ftp/fixtures/puttextfile
index b4f3b2b62d..b4f3b2b62d 100644
--- a/spec/ruby/library/net/ftp/fixtures/puttextfile
+++ b/spec/ruby/library/net-ftp/fixtures/puttextfile
diff --git a/spec/ruby/library/net-ftp/fixtures/server.rb b/spec/ruby/library/net-ftp/fixtures/server.rb
new file mode 100644
index 0000000000..9fc2beb57b
--- /dev/null
+++ b/spec/ruby/library/net-ftp/fixtures/server.rb
@@ -0,0 +1,279 @@
+ruby_version_is ""..."4.1" do
+  module NetFTPSpecs
+    class DummyFTP
+      attr_accessor :connect_message
+      attr_reader :login_user, :login_pass, :login_acct
+
+      # hostname or IP address
+      attr_reader :hostname
+      # port number
+      attr_reader :server_port
+
+      def initialize
+        @hostname = "127.0.0.1"
+        @server = TCPServer.new(@hostname, 0)
+        @server_port = @server.addr[1]
+
+        @handlers = {}
+        @commands = []
+        @connect_message = nil
+      end
+
+      def serve_once
+        @thread = Thread.new do
+          @socket = @server.accept
+          @socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, 1)
+          begin
+            handle_request
+          ensure
+            @socket.close
+          end
+        end
+      end
+
+      def handle_request
+        # Send out the welcome message.
+        response @connect_message || "220 Dummy FTP Server ready!"
+
+        begin
+          while command = @socket.gets
+            command, argument = command.chomp.split(" ", 2)
+
+            if command == "QUIT"
+              self.response("221 OK, bye")
+              break
+            elsif proc_handler = @handlers[command.downcase.to_sym]
+              if argument.nil?
+                proc_handler.call(self)
+              else
+                proc_handler.call(self, argument)
+              end
+            else
+              if argument.nil?
+                self.send(command.downcase.to_sym)
+              else
+                self.send(command.downcase.to_sym, argument)
+              end
+            end
+          end
+        rescue => e
+          self.error_response("Exception: #{e} #{e.backtrace.inspect}")
+        end
+      end
+
+      def error_response(text)
+        self.response("451 #{text}")
+      end
+
+      def response(text)
+        @socket.puts(text) unless @socket.closed?
+      end
+
+      def stop
+        @datasocket.close unless @datasocket.nil? || @datasocket.closed?
+        @server.close
+        @thread.join
+      end
+
+
+      ##
+      def handle(sym, &block)
+        @handlers[sym] = block
+      end
+
+      def should_receive(method)
+        @handler_for = method
+        self
+      end
+
+      def and_respond(text)
+        @handlers[@handler_for] = -> s, *args { s.response(text) }
+      end
+
+      ##
+      # FTP methods
+      ##
+
+      def abor
+        self.response("226 Closing data connection. (ABOR)")
+      end
+
+      def acct(account)
+        @login_acct = account
+        self.response("230 User '#{account}' logged in, proceed. (ACCT)")
+      end
+
+      def cdup
+        self.response("200 Command okay. (CDUP)")
+      end
+
+      def cwd(dir)
+        self.response("200 Command okay. (CWD #{dir})")
+      end
+
+      def dele(file)
+        self.response("250 Requested file action okay, completed. (DELE #{file})")
+      end
+
+      def eprt(arg)
+        _, _, host, port = arg.split("|")
+
+        @datasocket = TCPSocket.new(host, port)
+        self.response("200 port opened")
+      end
+
+      def help(param = :default)
+        if param == :default
+          self.response("211 System status, or system help reply. (HELP)")
+        else
+          self.response("211 System status, or system help reply. (HELP #{param})")
+        end
+      end
+
+      def list(folder)
+        self.response("150 opening ASCII connection for file list")
+        @datasocket.puts("-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb")
+        @datasocket.puts("-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb")
+        @datasocket.puts("-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb")
+        @datasocket.close()
+        self.response("226 transfer complete (LIST #{folder})")
+      end
+
+      def mdtm(filename)
+        self.response("213 19980705132316")
+      end
+
+      def mkd(foldername)
+        self.response(%Q{257 "#{foldername.gsub('"', '""')}" created.})
+      end
+
+      def nlst(folder = nil)
+        self.response("150 opening ASCII connection for file list")
+        @datasocket.puts("last_response_code.rb")
+        @datasocket.puts("list.rb")
+        @datasocket.puts("pwd.rb")
+        @datasocket.close()
+        self.response("226 transfer complete (NLST#{folder ? " #{folder}" : ""})")
+      end
+
+      def noop
+        self.response("200 Command okay. (NOOP)")
+      end
+
+      def pass(password)
+        @login_pass = password
+        self.response("230 User logged in, proceed. (PASS #{password})")
+      end
+
+      def port(arg)
+        nums = arg.split(",")
+
+        if nums[0] == "::1"
+          # IPv6
+          port = nums[1].to_i * 256 + nums[2].to_i
+          host = nums[0]
+        else
+          # IPv4
+          port = nums[4].to_i * 256 + nums[5].to_i
+          host = nums[0..3].join(".")
+        end
+
+        @datasocket = TCPSocket.new(host, port)
+        self.response("200 port opened")
+      end
+
+      def pwd
+        self.response('257 "/some/dir/" - current directory')
+      end
+
+      def retr(file)
+        self.response("125 Data transfer starting")
+        if @restart_at && @restart_at == 20
+          @datasocket.puts("of the file named '#{file}'.")
+          @restart_at = nil
+        else
+          @datasocket.puts("This is the content")
+          @datasocket.puts("of the file named '#{file}'.")
+        end
+        @datasocket.close()
+        self.response("226 Closing data connection. (RETR #{file})")
+      end
+
+      def rest(at_bytes)
+        @restart_at = at_bytes.to_i
+        self.response("350 Requested file action pending further information. (REST)")
+      end
+
+      def rmd(folder)
+        self.response("250 Requested file action okay, completed. (RMD #{folder})")
+      end
+
+      def rnfr(from)
+        @rename_from = from
+        self.response("350 Requested file action pending further information.")
+      end
+
+      def rnto(to)
+        self.response("250 Requested file action okay, completed. (Renamed #{@rename_from} to #{to})")
+        @rename_from = nil
+      end
+
+      def site(param)
+        self.response("200 Command okay. (SITE #{param})")
+      end
+
+      def size(filename)
+        if filename == "binary"
+          self.response("213 24")
+        else
+          self.response("213 1024")
+        end
+      end
+
+      def stat(param = :default)
+        if param == :default
+          self.response("211 System status, or system help reply. (STAT)")
+        else
+          self.response("211 System status, or system help reply. (STAT #{param})")
+        end
+      end
+
+      def stor(file)
+        tmp_file = tmp("#{file}file", false)
+
+        self.response("125 Data transfer starting.")
+
+        mode = @restart_at ? "a" : "w"
+
+        File.open(tmp_file, mode + "b") do |f|
+          loop do
+            data = @datasocket.recv(1024)
+            break if !data || data.empty?
+            f << data
+          end
+        end
+
+        @datasocket.close()
+        self.response("200 OK, Data received. (STOR #{file})")
+      end
+
+      def appe(file)
+        @restart_at = true
+        stor(file)
+      end
+
+      def syst
+        self.response("215 FTP Dummy Server (SYST)")
+      end
+
+      def type(type)
+        self.response("200 TYPE switched to #{type}")
+      end
+
+      def user(name)
+        @login_user = name
+        self.response("230 User logged in, proceed. (USER #{name})")
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/get_spec.rb b/spec/ruby/library/net-ftp/get_spec.rb
new file mode 100644
index 0000000000..6a8aa3e206
--- /dev/null
+++ b/spec/ruby/library/net-ftp/get_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/gettextfile'
+  require_relative 'shared/getbinaryfile'
+
+  describe "Net::FTP#get (binary mode)" do
+    before :each do
+      @binary_mode = true
+    end
+
+    it_behaves_like :net_ftp_getbinaryfile, :get
+  end
+
+  describe "Net::FTP#get (text mode)" do
+    before :each do
+      @binary_mode = false
+    end
+
+    it_behaves_like :net_ftp_gettextfile, :get
+  end
+end
diff --git a/spec/ruby/library/net-ftp/getbinaryfile_spec.rb b/spec/ruby/library/net-ftp/getbinaryfile_spec.rb
new file mode 100644
index 0000000000..6b2d38edf5
--- /dev/null
+++ b/spec/ruby/library/net-ftp/getbinaryfile_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/getbinaryfile'
+
+  describe "Net::FTP#getbinaryfile" do
+    it_behaves_like :net_ftp_getbinaryfile, :getbinaryfile
+  end
+end
diff --git a/spec/ruby/library/net-ftp/getdir_spec.rb b/spec/ruby/library/net-ftp/getdir_spec.rb
new file mode 100644
index 0000000000..2ff62d399d
--- /dev/null
+++ b/spec/ruby/library/net-ftp/getdir_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'shared/pwd'
+
+  describe "Net::FTP#getdir" do
+    it_behaves_like :net_ftp_pwd, :getdir
+  end
+end
diff --git a/spec/ruby/library/net-ftp/gettextfile_spec.rb b/spec/ruby/library/net-ftp/gettextfile_spec.rb
new file mode 100644
index 0000000000..3bb037663b
--- /dev/null
+++ b/spec/ruby/library/net-ftp/gettextfile_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/gettextfile'
+
+  describe "Net::FTP#gettextfile" do
+    it_behaves_like :net_ftp_gettextfile, :gettextfile
+  end
+end
diff --git a/spec/ruby/library/net-ftp/help_spec.rb b/spec/ruby/library/net-ftp/help_spec.rb
new file mode 100644
index 0000000000..bb52fb9e69
--- /dev/null
+++ b/spec/ruby/library/net-ftp/help_spec.rb
@@ -0,0 +1,69 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#help" do
+    def with_connection
+      yield
+    end
+
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "writes the HELP command to the server" do
+      @ftp.help
+      @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
+    end
+
+    it "returns the server's response" do
+      @ftp.help.should == "211 System status, or system help reply. (HELP)\n"
+    end
+
+    it "writes the HELP command with an optional parameter to the socket" do
+      @ftp.help("some parameter").should == "211 System status, or system help reply. (HELP some parameter)\n"
+    end
+
+    it "does not raise any error when the response code is 211" do
+      @server.should_receive(:help).and_respond("211 System status, or system help reply.")
+      -> { @ftp.help }.should_not.raise
+    end
+
+    it "does not raise any error when the response code is 214" do
+      @server.should_receive(:help).and_respond("214 Help message.")
+      -> { @ftp.help }.should_not.raise
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:help).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.help }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:help).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.help }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:help).and_respond("502 Command not implemented.")
+      -> { @ftp.help }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:help).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.help }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/initialize_spec.rb b/spec/ruby/library/net-ftp/initialize_spec.rb
new file mode 100644
index 0000000000..9079ad6b79
--- /dev/null
+++ b/spec/ruby/library/net-ftp/initialize_spec.rb
@@ -0,0 +1,408 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#initialize" do
+    before :each do
+      @ftp = Net::FTP.allocate
+      @ftp.stub!(:connect)
+      @port_args = []
+      @port_args << 21
+    end
+
+    it "is private" do
+      Net::FTP.private_instance_methods(false).should.include?(:initialize)
+    end
+
+    it "sets self into binary mode" do
+      @ftp.binary.should == nil
+      @ftp.send(:initialize)
+      @ftp.binary.should == true
+    end
+
+    it "sets self into active mode" do
+      @ftp.passive.should == nil
+      @ftp.send(:initialize)
+      @ftp.passive.should == false
+    end
+
+    it "sets self into non-debug mode" do
+      @ftp.debug_mode.should == nil
+      @ftp.send(:initialize)
+      @ftp.debug_mode.should == false
+    end
+
+    it "sets self to not resume file uploads/downloads" do
+      @ftp.resume.should == nil
+      @ftp.send(:initialize)
+      @ftp.resume.should == false
+    end
+
+    describe "when passed no arguments" do
+      it "does not try to connect" do
+        @ftp.should_not_receive(:connect)
+        @ftp.send(:initialize)
+      end
+    end
+
+    describe "when passed host" do
+      it "tries to connect to the passed host" do
+        @ftp.should_receive(:connect).with("localhost", *@port_args)
+        @ftp.send(:initialize, "localhost")
+      end
+    end
+
+    describe "when passed host, user" do
+      it "tries to connect to the passed host" do
+        @ftp.should_receive(:connect).with("localhost", *@port_args)
+        @ftp.send(:initialize, "localhost")
+      end
+
+      it "tries to login with the passed username" do
+        @ftp.should_receive(:login).with("rubyspec", nil, nil)
+        @ftp.send(:initialize, "localhost", "rubyspec")
+      end
+    end
+
+    describe "when passed host, user, password" do
+      it "tries to connect to the passed host" do
+        @ftp.should_receive(:connect).with("localhost", *@port_args)
+        @ftp.send(:initialize, "localhost")
+      end
+
+      it "tries to login with the passed username and password" do
+        @ftp.should_receive(:login).with("rubyspec", "rocks", nil)
+        @ftp.send(:initialize, "localhost", "rubyspec", "rocks")
+      end
+    end
+
+    describe "when passed host, user" do
+      it "tries to connect to the passed host" do
+        @ftp.should_receive(:connect).with("localhost", *@port_args)
+        @ftp.send(:initialize, "localhost")
+      end
+
+      it "tries to login with the passed username, password and account" do
+        @ftp.should_receive(:login).with("rubyspec", "rocks", "account")
+        @ftp.send(:initialize, "localhost", "rubyspec", "rocks", "account")
+      end
+    end
+
+    before :each do
+      @ftp.stub!(:login)
+    end
+
+    describe 'when the host' do
+      describe 'is set' do
+        describe 'and port option' do
+          describe 'is set' do
+            it 'tries to connect to the host on the specified port' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({ port: 8080 })
+              @ftp.should_receive(:connect).with('localhost', 8080)
+
+              @ftp.send(:initialize, 'localhost', options)
+            end
+          end
+
+          describe 'is not set' do
+            it 'tries to connect to the host without a port' do
+              @ftp.should_receive(:connect).with("localhost", *@port_args)
+
+              @ftp.send(:initialize, 'localhost')
+            end
+          end
+        end
+
+        describe 'when the username option' do
+          describe 'is set' do
+            describe 'and the password option' do
+              describe 'is set' do
+                describe 'and the account option' do
+                  describe 'is set' do
+                    it 'tries to log in with the supplied parameters' do
+                      options = mock('ftp initialize options')
+                      options.should_receive(:to_hash).and_return({ username: 'a', password: 'topsecret', account: 'b' })
+                      @ftp.should_receive(:login).with('a', 'topsecret', 'b')
+
+                      @ftp.send(:initialize, 'localhost', options)
+                    end
+                  end
+
+                  describe 'is unset' do
+                    it 'tries to log in with the supplied parameters' do
+                      options = mock('ftp initialize options')
+                      options.should_receive(:to_hash).and_return({ username: 'a', password: 'topsecret' })
+                      @ftp.should_receive(:login).with('a', 'topsecret', nil)
+
+                      @ftp.send(:initialize, 'localhost', options)
+                    end
+                  end
+                end
+              end
+
+              describe 'is unset' do
+                describe 'and the account option' do
+                  describe 'is set' do
+                    it 'tries to log in with the supplied parameters' do
+                      options = mock('ftp initialize options')
+                      options.should_receive(:to_hash).and_return({ username: 'a', account: 'b' })
+                      @ftp.should_receive(:login).with('a', nil, 'b')
+
+                      @ftp.send(:initialize, 'localhost', options)
+                    end
+                  end
+
+                  describe 'is unset' do
+                    it 'tries to log in with the supplied parameters' do
+                      options = mock('ftp initialize options')
+                      options.should_receive(:to_hash).and_return({ username: 'a'})
+                      @ftp.should_receive(:login).with('a', nil, nil)
+
+                      @ftp.send(:initialize, 'localhost', options)
+                    end
+                  end
+                end
+              end
+            end
+          end
+
+          describe 'is not set' do
+            it 'does not try to log in' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({})
+              @ftp.should_not_receive(:login)
+
+              @ftp.send(:initialize, 'localhost', options)
+            end
+          end
+        end
+      end
+
+      describe 'is unset' do
+        it 'does not try to connect' do
+          @ftp.should_not_receive(:connect)
+
+          @ftp.send(:initialize)
+        end
+
+        it 'does not try to log in' do
+          @ftp.should_not_receive(:login)
+
+          @ftp.send(:initialize)
+        end
+      end
+    end
+
+    describe 'when the passive option' do
+      describe 'is set' do
+        describe 'to true' do
+          it 'sets passive to true' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ passive: true })
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.passive.should == true
+          end
+        end
+
+        describe 'to false' do
+          it 'sets passive to false' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ passive: false })
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.passive.should == false
+          end
+        end
+      end
+
+      describe 'is unset' do
+        it 'sets passive to false' do
+          @ftp.send(:initialize)
+          @ftp.passive.should == false
+        end
+      end
+    end
+
+    describe 'when the debug_mode option' do
+      describe 'is set' do
+        describe 'to true' do
+          it 'sets debug_mode to true' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ debug_mode: true })
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.debug_mode.should == true
+          end
+        end
+
+        describe 'to false' do
+          it 'sets debug_mode to false' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ debug_mode: false })
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.debug_mode.should == false
+          end
+        end
+      end
+
+      describe 'is unset' do
+        it 'sets debug_mode to false' do
+          @ftp.send(:initialize)
+          @ftp.debug_mode.should == false
+        end
+      end
+    end
+
+    describe 'when the open_timeout option' do
+      describe 'is set' do
+        it 'sets open_timeout to the specified value' do
+          options = mock('ftp initialize options')
+          options.should_receive(:to_hash).and_return({ open_timeout: 42 })
+
+          @ftp.send(:initialize, nil, options)
+          @ftp.open_timeout.should == 42
+        end
+      end
+
+      describe 'is not set' do
+        it 'sets open_timeout to nil' do
+          @ftp.send(:initialize)
+          @ftp.open_timeout.should == nil
+        end
+      end
+    end
+
+    describe 'when the read_timeout option' do
+      describe 'is set' do
+        it 'sets read_timeout to the specified value' do
+          options = mock('ftp initialize options')
+          options.should_receive(:to_hash).and_return({ read_timeout: 100 })
+
+          @ftp.send(:initialize, nil, options)
+          @ftp.read_timeout.should == 100
+        end
+      end
+
+      describe 'is not set' do
+        it 'sets read_timeout to the default value' do
+          @ftp.send(:initialize)
+          @ftp.read_timeout.should == 60
+        end
+      end
+    end
+
+    describe 'when the ssl_handshake_timeout option' do
+      describe 'is set' do
+        it 'sets ssl_handshake_timeout to the specified value' do
+          options = mock('ftp initialize options')
+          options.should_receive(:to_hash).and_return({ ssl_handshake_timeout: 23 })
+
+          @ftp.send(:initialize, nil, options)
+          @ftp.ssl_handshake_timeout.should == 23
+        end
+      end
+
+      describe 'is not set' do
+        it 'sets ssl_handshake_timeout to nil' do
+          @ftp.send(:initialize)
+          @ftp.ssl_handshake_timeout.should == nil
+        end
+      end
+    end
+
+    describe 'when the ssl option' do
+      describe 'is set' do
+        describe "and the ssl option's value is true" do
+          it 'initializes ssl_context to a blank SSLContext object' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ ssl: true })
+
+            ssl_context = OpenSSL::SSL::SSLContext.allocate
+            ssl_context.stub!(:set_params)
+
+            OpenSSL::SSL::SSLContext.should_receive(:new).and_return(ssl_context)
+            ssl_context.should_receive(:set_params).with({})
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.instance_variable_get(:@ssl_context).should == ssl_context
+          end
+        end
+
+        describe "and the ssl option's value is a hash" do
+          it 'initializes ssl_context to a configured SSLContext object' do
+            options = mock('ftp initialize options')
+            options.should_receive(:to_hash).and_return({ ssl: {key: 'value'} })
+
+            ssl_context = OpenSSL::SSL::SSLContext.allocate
+            ssl_context.stub!(:set_params)
+
+            OpenSSL::SSL::SSLContext.should_receive(:new).and_return(ssl_context)
+            ssl_context.should_receive(:set_params).with({key: 'value'})
+
+            @ftp.send(:initialize, nil, options)
+            @ftp.instance_variable_get(:@ssl_context).should == ssl_context
+          end
+        end
+
+        describe 'and private_data_connection' do
+          describe 'is set' do
+            it 'sets private_data_connection to that value' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({ ssl: true, private_data_connection: 'true' })
+
+              @ftp.send(:initialize, nil, options)
+              @ftp.instance_variable_get(:@private_data_connection).should == 'true'
+            end
+          end
+
+          describe 'is not set' do
+            it 'sets private_data_connection to nil' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({ ssl: true })
+
+              @ftp.send(:initialize, nil, options)
+              @ftp.instance_variable_get(:@private_data_connection).should == true
+            end
+          end
+        end
+      end
+
+      describe 'is not set' do
+        it 'sets ssl_context to nil' do
+          options = mock('ftp initialize options')
+          options.should_receive(:to_hash).and_return({})
+
+          @ftp.send(:initialize, nil, options)
+          @ftp.instance_variable_get(:@ssl_context).should == nil
+        end
+
+        describe 'private_data_connection' do
+          describe 'is set' do
+            it 'raises an ArgumentError' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({ private_data_connection: true })
+
+              -> {
+                @ftp.send(:initialize, nil, options)
+              }.should.raise(ArgumentError, /private_data_connection can be set to true only when ssl is enabled/)
+            end
+          end
+
+          describe 'is not set' do
+            it 'sets private_data_connection to false' do
+              options = mock('ftp initialize options')
+              options.should_receive(:to_hash).and_return({})
+
+              @ftp.send(:initialize, nil, options)
+              @ftp.instance_variable_get(:@private_data_connection).should == false
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/last_response_code_spec.rb b/spec/ruby/library/net-ftp/last_response_code_spec.rb
new file mode 100644
index 0000000000..03329758b5
--- /dev/null
+++ b/spec/ruby/library/net-ftp/last_response_code_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'shared/last_response_code'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#last_response_code" do
+    it_behaves_like :net_ftp_last_response_code, :last_response_code
+  end
+end
diff --git a/spec/ruby/library/net-ftp/last_response_spec.rb b/spec/ruby/library/net-ftp/last_response_spec.rb
new file mode 100644
index 0000000000..7cda9fa7a4
--- /dev/null
+++ b/spec/ruby/library/net-ftp/last_response_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#last_response" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "returns the last response" do
+      @ftp.last_response.should == "220 Dummy FTP Server ready!\n"
+      @ftp.help
+      @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/lastresp_spec.rb b/spec/ruby/library/net-ftp/lastresp_spec.rb
new file mode 100644
index 0000000000..c373670ec4
--- /dev/null
+++ b/spec/ruby/library/net-ftp/lastresp_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'shared/last_response_code'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#lastresp" do
+    it_behaves_like :net_ftp_last_response_code, :lastresp
+  end
+end
diff --git a/spec/ruby/library/net-ftp/list_spec.rb b/spec/ruby/library/net-ftp/list_spec.rb
new file mode 100644
index 0000000000..297d100dd9
--- /dev/null
+++ b/spec/ruby/library/net-ftp/list_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/list'
+
+  describe "Net::FTP#list" do
+    it_behaves_like :net_ftp_list, :list
+  end
+end
diff --git a/spec/ruby/library/net-ftp/login_spec.rb b/spec/ruby/library/net-ftp/login_spec.rb
new file mode 100644
index 0000000000..05bb6b7f81
--- /dev/null
+++ b/spec/ruby/library/net-ftp/login_spec.rb
@@ -0,0 +1,198 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#login" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    describe "when passed no arguments" do
+      it "sends the USER command with 'anonymous' as name to the server" do
+        @ftp.login
+        @server.login_user.should == "anonymous"
+      end
+
+      it "sends 'anonymous@' as a password when required" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @ftp.login
+        @server.login_pass.should == "anonymous@"
+      end
+
+      it "raises a Net::FTPReplyError when the server requests an account" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @server.should_receive(:pass).and_respond("332 Need account for login.")
+        -> { @ftp.login }.should.raise(Net::FTPReplyError)
+      end
+    end
+
+    describe "when passed name" do
+      it "sends the USER command with the passed name to the server" do
+        @ftp.login("rubyspec")
+        @server.login_user.should == "rubyspec"
+      end
+
+      it "raises a Net::FTPReplyError when the server requests a password, but none was given" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        -> { @ftp.login("rubyspec") }.should.raise(Net::FTPReplyError)
+      end
+
+      it "raises a Net::FTPReplyError when the server requests an account, but none was given" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @server.should_receive(:pass).and_respond("332 Need account for login.")
+        -> { @ftp.login("rubyspec") }.should.raise(Net::FTPReplyError)
+      end
+    end
+
+    describe "when passed name, password" do
+      it "sends the USER command with the passed name to the server" do
+        @ftp.login("rubyspec", "rocks")
+        @server.login_user.should == "rubyspec"
+      end
+
+      it "sends the passed password when required" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @ftp.login("rubyspec", "rocks")
+        @server.login_pass.should == "rocks"
+      end
+
+      it "raises a Net::FTPReplyError when the server requests an account" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @server.should_receive(:pass).and_respond("332 Need account for login.")
+        -> { @ftp.login("rubyspec", "rocks") }.should.raise(Net::FTPReplyError)
+      end
+    end
+
+    describe "when passed name, password, account" do
+      it "sends the USER command with the passed name to the server" do
+        @ftp.login("rubyspec", "rocks", "account")
+        @server.login_user.should == "rubyspec"
+      end
+
+      it "sends the passed password when required" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @ftp.login("rubyspec", "rocks", "account")
+        @server.login_pass.should == "rocks"
+      end
+
+      it "sends the passed account when required" do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @server.should_receive(:pass).and_respond("332 Need account for login.")
+        @ftp.login("rubyspec", "rocks", "account")
+        @server.login_acct.should == "account"
+      end
+    end
+
+    describe "when the USER command fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:user).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:user).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:user).and_respond("502 Command not implemented.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:user).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:user).and_respond("530 Not logged in.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when the PASS command fails" do
+      before :each do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+      end
+
+      it "does not raise an Error when the response code is 202" do
+        @server.should_receive(:pass).and_respond("202 Command not implemented, superfluous at this site.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should_not.raise
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:pass).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:pass).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:pass).and_respond("502 Command not implemented.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:pass).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:pass).and_respond("530 Not logged in.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when the ACCT command fails" do
+      before :each do
+        @server.should_receive(:user).and_respond("331 User name okay, need password.")
+        @server.should_receive(:pass).and_respond("332 Need account for login.")
+      end
+
+      it "does not raise an Error when the response code is 202" do
+        @server.should_receive(:acct).and_respond("202 Command not implemented, superfluous at this site.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should_not.raise
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:acct).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:acct).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:acct).and_respond("502 Command not implemented.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:acct).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:acct).and_respond("530 Not logged in.")
+        -> { @ftp.login("rubyspec", "rocks", "account") }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/ls_spec.rb b/spec/ruby/library/net-ftp/ls_spec.rb
new file mode 100644
index 0000000000..f8fdb10e8f
--- /dev/null
+++ b/spec/ruby/library/net-ftp/ls_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/list'
+
+  describe "Net::FTP#ls" do
+    it_behaves_like :net_ftp_list, :ls
+  end
+end
diff --git a/spec/ruby/library/net-ftp/mdtm_spec.rb b/spec/ruby/library/net-ftp/mdtm_spec.rb
new file mode 100644
index 0000000000..effd22a6e4
--- /dev/null
+++ b/spec/ruby/library/net-ftp/mdtm_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#mdtm" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the MDTM with the passed filename command to the server" do
+      @ftp.mdtm("test.file")
+      @ftp.last_response.should == "213 19980705132316\n"
+    end
+
+    it "returns the last modification time of the passed file" do
+      @ftp.mdtm("test.file").should == "19980705132316"
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:mdtm).and_respond("550 Requested action not taken.")
+      -> { @ftp.mdtm("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:mdtm).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.mdtm("test.file") }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/mkdir_spec.rb b/spec/ruby/library/net-ftp/mkdir_spec.rb
new file mode 100644
index 0000000000..6daeb7c022
--- /dev/null
+++ b/spec/ruby/library/net-ftp/mkdir_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#mkdir" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the MKD command with the passed pathname to the server" do
+      @ftp.mkdir("test.folder")
+      @ftp.last_response.should == %{257 "test.folder" created.\n}
+    end
+
+    it "returns the path to the newly created directory" do
+      @ftp.mkdir("test.folder").should == "test.folder"
+      @ftp.mkdir("/absolute/path/to/test.folder").should == "/absolute/path/to/test.folder"
+      @ftp.mkdir("relative/path/to/test.folder").should == "relative/path/to/test.folder"
+      @ftp.mkdir('/usr/dm/foo"bar').should == '/usr/dm/foo"bar'
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:mkd).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:mkd).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:mkd).and_respond("502 Command not implemented.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:mkd).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:mkd).and_respond("530 Not logged in.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:mkd).and_respond("550 Requested action not taken.")
+      -> { @ftp.mkdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/mtime_spec.rb b/spec/ruby/library/net-ftp/mtime_spec.rb
new file mode 100644
index 0000000000..694036a296
--- /dev/null
+++ b/spec/ruby/library/net-ftp/mtime_spec.rb
@@ -0,0 +1,53 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#mtime" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the MDTM with the passed filename command to the server" do
+      @ftp.mtime("test.file")
+      @ftp.last_response.should == "213 19980705132316\n"
+    end
+
+    describe "when passed filename" do
+      it "returns the last modification time of the passed file as a Time object in the local time" do
+        @ftp.mtime("test.file").should == Time.gm("1998", "07", "05", "13", "23", "16")
+      end
+    end
+
+    describe "when passed filename, local_time" do
+      it "returns the last modification time as a Time object in UTC when local_time is true" do
+        @ftp.mtime("test.file", true).should == Time.local("1998", "07", "05", "13", "23", "16")
+      end
+
+      it "returns the last modification time as a Time object in the local time when local_time is false" do
+        @ftp.mtime("test.file", false).should == Time.gm("1998", "07", "05", "13", "23", "16")
+      end
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:mdtm).and_respond("550 Requested action not taken.")
+      -> { @ftp.mtime("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:mdtm).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.mtime("test.file") }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/nlst_spec.rb b/spec/ruby/library/net-ftp/nlst_spec.rb
new file mode 100644
index 0000000000..87b80b43fd
--- /dev/null
+++ b/spec/ruby/library/net-ftp/nlst_spec.rb
@@ -0,0 +1,95 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#nlst" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.passive = false
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    describe "when passed no arguments" do
+      it "returns an Array containing a list of files in the current dir" do
+        @ftp.nlst.should == ["last_response_code.rb", "list.rb", "pwd.rb"]
+        @ftp.last_response.should == "226 transfer complete (NLST)\n"
+      end
+    end
+
+    describe "when passed dir" do
+      it "returns an Array containing a list of files in the passed dir" do
+        @ftp.nlst("test.folder").should == ["last_response_code.rb", "list.rb", "pwd.rb"]
+        @ftp.last_response.should == "226 transfer complete (NLST test.folder)\n"
+      end
+    end
+
+    describe "when the NLST command fails" do
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:nlst).and_respond("450 Requested file action not taken..")
+        -> { @ftp.nlst }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:nlst).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:nlst).and_respond("501 Syntax error, command unrecognized.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:nlst).and_respond("502 Command not implemented.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:nlst).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.nlst }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:nlst).and_respond("530 Not logged in.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.nlst }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.nlst }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/noop_spec.rb b/spec/ruby/library/net-ftp/noop_spec.rb
new file mode 100644
index 0000000000..43c48e355a
--- /dev/null
+++ b/spec/ruby/library/net-ftp/noop_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#noop" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the NOOP command to the server" do
+      @ftp.noop
+      @ftp.last_response.should == "200 Command okay. (NOOP)\n"
+    end
+
+    it "returns nil" do
+      @ftp.noop.should == nil
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:noop).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.noop }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:noop).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.noop }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/open_spec.rb b/spec/ruby/library/net-ftp/open_spec.rb
new file mode 100644
index 0000000000..2d6477ec4d
--- /dev/null
+++ b/spec/ruby/library/net-ftp/open_spec.rb
@@ -0,0 +1,58 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP.open" do
+    before :each do
+      @ftp = mock("Net::FTP instance")
+      Net::FTP.stub!(:new).and_return(@ftp)
+    end
+
+    describe "when passed no block" do
+      it "returns a new Net::FTP instance" do
+        Net::FTP.open("localhost").should.equal?(@ftp)
+      end
+
+      it "passes the passed arguments down to Net::FTP.new" do
+        Net::FTP.should_receive(:new).with("localhost", "user", "password", "account")
+        Net::FTP.open("localhost", "user", "password", "account")
+      end
+    end
+
+    describe "when passed a block" do
+      before :each do
+        @ftp.stub!(:close)
+      end
+
+      it "yields a new Net::FTP instance to the passed block" do
+        yielded = false
+        Net::FTP.open("localhost") do |ftp|
+          yielded = true
+          ftp.should.equal?(@ftp)
+        end
+        yielded.should == true
+      end
+
+      it "closes the Net::FTP instance after yielding" do
+        Net::FTP.open("localhost") do |ftp|
+          ftp.should_receive(:close)
+        end
+      end
+
+      it "closes the Net::FTP instance even if an exception is raised while yielding" do
+        begin
+          Net::FTP.open("localhost") do |ftp|
+            ftp.should_receive(:close)
+            raise ArgumentError, "some exception"
+          end
+        rescue ArgumentError
+        end
+      end
+
+      it "returns the block's return value" do
+        Net::FTP.open("localhost") { :test }.should == :test
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/passive_spec.rb b/spec/ruby/library/net-ftp/passive_spec.rb
new file mode 100644
index 0000000000..6acabd3f98
--- /dev/null
+++ b/spec/ruby/library/net-ftp/passive_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#passive" do
+    it "returns true when self is in passive mode" do
+      ftp = Net::FTP.new
+      ftp.passive.should == false
+
+      ftp.passive = true
+      ftp.passive.should == true
+    end
+
+    it "is the value of Net::FTP.default_value by default" do
+      ruby_exe(fixture(__FILE__, "passive.rb")).should == "true"
+    end
+  end
+
+  describe "Net::FTP#passive=" do
+    it "sets self to passive mode when passed true" do
+      ftp = Net::FTP.new
+
+      ftp.passive = true
+      ftp.passive.should == true
+
+      ftp.passive = false
+      ftp.passive.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/put_spec.rb b/spec/ruby/library/net-ftp/put_spec.rb
new file mode 100644
index 0000000000..603409e283
--- /dev/null
+++ b/spec/ruby/library/net-ftp/put_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/puttextfile'
+  require_relative 'shared/putbinaryfile'
+
+  describe "Net::FTP#put (binary mode)" do
+    before :each do
+      @binary_mode = true
+    end
+
+    it_behaves_like :net_ftp_putbinaryfile, :put
+  end
+
+  describe "Net::FTP#put (text mode)" do
+    before :each do
+      @binary_mode = false
+    end
+
+    it_behaves_like :net_ftp_puttextfile, :put
+  end
+end
diff --git a/spec/ruby/library/net-ftp/putbinaryfile_spec.rb b/spec/ruby/library/net-ftp/putbinaryfile_spec.rb
new file mode 100644
index 0000000000..ce8a6f0473
--- /dev/null
+++ b/spec/ruby/library/net-ftp/putbinaryfile_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/putbinaryfile'
+
+  describe "Net::FTP#putbinaryfile" do
+    it_behaves_like :net_ftp_putbinaryfile, :putbinaryfile
+  end
+end
diff --git a/spec/ruby/library/net-ftp/puttextfile_spec.rb b/spec/ruby/library/net-ftp/puttextfile_spec.rb
new file mode 100644
index 0000000000..b4ab86aab1
--- /dev/null
+++ b/spec/ruby/library/net-ftp/puttextfile_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+  require_relative 'shared/puttextfile'
+
+  describe "Net::FTP#puttextfile" do
+    it_behaves_like :net_ftp_puttextfile, :puttextfile
+  end
+end
diff --git a/spec/ruby/library/net-ftp/pwd_spec.rb b/spec/ruby/library/net-ftp/pwd_spec.rb
new file mode 100644
index 0000000000..53692b553f
--- /dev/null
+++ b/spec/ruby/library/net-ftp/pwd_spec.rb
@@ -0,0 +1,56 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#pwd" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the PWD command to the server" do
+      @ftp.pwd
+      @ftp.last_response.should == "257 \"/some/dir/\" - current directory\n"
+    end
+
+    it "returns the current directory" do
+      @ftp.pwd.should == "/some/dir/"
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:pwd).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.pwd }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:pwd).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.pwd }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:pwd).and_respond("502 Command not implemented.")
+      -> { @ftp.pwd }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:pwd).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.pwd }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:pwd).and_respond("550 Requested action not taken.")
+      -> { @ftp.pwd }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/quit_spec.rb b/spec/ruby/library/net-ftp/quit_spec.rb
new file mode 100644
index 0000000000..1af0107d34
--- /dev/null
+++ b/spec/ruby/library/net-ftp/quit_spec.rb
@@ -0,0 +1,36 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#quit" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the QUIT command to the server" do
+      @ftp.quit
+      @ftp.last_response.should == "221 OK, bye\n"
+    end
+
+    it "does not close the socket automatically" do
+      @ftp.quit
+      @ftp.closed?.should == false
+    end
+
+    it "returns nil" do
+      @ftp.quit.should == nil
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/rename_spec.rb b/spec/ruby/library/net-ftp/rename_spec.rb
new file mode 100644
index 0000000000..6541fe5301
--- /dev/null
+++ b/spec/ruby/library/net-ftp/rename_spec.rb
@@ -0,0 +1,97 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#rename" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    describe "when passed from_name, to_name" do
+      it "sends the RNFR command with the passed from_name and the RNTO command with the passed to_name to the server" do
+        @ftp.rename("from.file", "to.file")
+        @ftp.last_response.should == "250 Requested file action okay, completed. (Renamed from.file to to.file)\n"
+      end
+
+      it "returns something" do
+        @ftp.rename("from.file", "to.file").should == nil
+      end
+    end
+
+    describe "when the RNFR command fails" do
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:rnfr).and_respond("450 Requested file action not taken.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 550" do
+        @server.should_receive(:rnfr).and_respond("550 Requested action not taken.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:rnfr).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:rnfr).and_respond("502 Command not implemented.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:rnfr).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:rnfr).and_respond("530 Not logged in.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when the RNTO command fails" do
+      it "raises a Net::FTPPermError when the response code is 532" do
+        @server.should_receive(:rnfr).and_respond("532 Need account for storing files.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 553" do
+        @server.should_receive(:rnto).and_respond("553 Requested action not taken.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:rnto).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:rnto).and_respond("502 Command not implemented.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:rnto).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:rnto).and_respond("530 Not logged in.")
+        -> { @ftp.rename("from.file", "to.file") }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/resume_spec.rb b/spec/ruby/library/net-ftp/resume_spec.rb
new file mode 100644
index 0000000000..5ec565d155
--- /dev/null
+++ b/spec/ruby/library/net-ftp/resume_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#resume" do
+    it "returns true when self is set to resume uploads/downloads" do
+      ftp = Net::FTP.new
+      ftp.resume.should == false
+
+      ftp.resume = true
+      ftp.resume.should == true
+    end
+  end
+
+  describe "Net::FTP#resume=" do
+    it "sets self to resume uploads/downloads when set to true" do
+      ftp = Net::FTP.new
+      ftp.resume = true
+      ftp.resume.should == true
+
+      ftp.resume = false
+      ftp.resume.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/retrbinary_spec.rb b/spec/ruby/library/net-ftp/retrbinary_spec.rb
new file mode 100644
index 0000000000..ff8c8098a4
--- /dev/null
+++ b/spec/ruby/library/net-ftp/retrbinary_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#retrbinary" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the passed command to the server" do
+      @ftp.retrbinary("RETR test", 4096) {}
+      @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
+    end
+
+    it "yields the received content as binary blocks of the passed size" do
+      res = []
+      @ftp.retrbinary("RETR test", 10) { |bin| res << bin }
+      res.should == [ "This is th", "e content\n", "of the fil", "e named 't", "est'.\n" ]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/retrlines_spec.rb b/spec/ruby/library/net-ftp/retrlines_spec.rb
new file mode 100644
index 0000000000..2963da14f7
--- /dev/null
+++ b/spec/ruby/library/net-ftp/retrlines_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#retrlines" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the passed command over the socket" do
+      @ftp.retrlines("LIST test.dir") {}
+      @ftp.last_response.should == "226 transfer complete (LIST test.dir)\n"
+    end
+
+    it "yields each received line to the passed block" do
+      res = []
+      @ftp.retrlines("LIST test.dir") { |x| res << x }
+      res.should == [
+        "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
+        "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
+        "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
+      ]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/return_code_spec.rb b/spec/ruby/library/net-ftp/return_code_spec.rb
new file mode 100644
index 0000000000..fcf5a32aa7
--- /dev/null
+++ b/spec/ruby/library/net-ftp/return_code_spec.rb
@@ -0,0 +1,27 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#return_code" do
+    before :each do
+      @ftp = Net::FTP.new
+    end
+
+    it "outputs a warning and returns a newline" do
+      -> do
+        @ftp.return_code.should == "\n"
+      end.should complain(/warning: Net::FTP#return_code is obsolete and do nothing/)
+    end
+  end
+
+  describe "Net::FTP#return_code=" do
+    before :each do
+      @ftp = Net::FTP.new
+    end
+
+    it "outputs a warning" do
+      -> { @ftp.return_code = 123 }.should complain(/warning: Net::FTP#return_code= is obsolete and do nothing/)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/rmdir_spec.rb b/spec/ruby/library/net-ftp/rmdir_spec.rb
new file mode 100644
index 0000000000..23650ebcc8
--- /dev/null
+++ b/spec/ruby/library/net-ftp/rmdir_spec.rb
@@ -0,0 +1,61 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#rmdir" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the RMD command with the passed pathname to the server" do
+      @ftp.rmdir("test.folder")
+      @ftp.last_response.should == "250 Requested file action okay, completed. (RMD test.folder)\n"
+    end
+
+    it "returns nil" do
+      @ftp.rmdir("test.folder").should == nil
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:rmd).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:rmd).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:rmd).and_respond("502 Command not implemented.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:rmd).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:rmd).and_respond("530 Not logged in.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:rmd).and_respond("550 Requested action not taken.")
+      -> { @ftp.rmdir("test.folder") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/sendcmd_spec.rb b/spec/ruby/library/net-ftp/sendcmd_spec.rb
new file mode 100644
index 0000000000..67dbd3bdb8
--- /dev/null
+++ b/spec/ruby/library/net-ftp/sendcmd_spec.rb
@@ -0,0 +1,57 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#sendcmd" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the passed command to the server" do
+      @ftp.sendcmd("HELP")
+      @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
+    end
+
+    it "returns the server's response" do
+      @ftp.sendcmd("HELP").should == "211 System status, or system help reply. (HELP)\n"
+    end
+
+    it "raises no error when the response code is 1xx, 2xx or 3xx" do
+      @server.should_receive(:help).and_respond("120 Service ready in nnn minutes.")
+      -> { @ftp.sendcmd("HELP") }.should_not.raise
+
+      @server.should_receive(:help).and_respond("200 Command okay.")
+      -> { @ftp.sendcmd("HELP") }.should_not.raise
+
+      @server.should_receive(:help).and_respond("350 Requested file action pending further information.")
+      -> { @ftp.sendcmd("HELP") }.should_not.raise
+    end
+
+    it "raises a Net::FTPTempError when the response code is 4xx" do
+      @server.should_receive(:help).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.sendcmd("HELP") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 5xx" do
+      @server.should_receive(:help).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.sendcmd("HELP") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPProtoError when the response code is not between 1xx-5xx" do
+      @server.should_receive(:help).and_respond("999 Invalid response.")
+      -> { @ftp.sendcmd("HELP") }.should.raise(Net::FTPProtoError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/set_socket_spec.rb b/spec/ruby/library/net-ftp/set_socket_spec.rb
new file mode 100644
index 0000000000..ad83dfcc4f
--- /dev/null
+++ b/spec/ruby/library/net-ftp/set_socket_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+
+  describe "Net::FTP#set_socket" do
+    # TODO: I won't spec this method, as it is not used
+    #       anywhere and it should be private anyway.
+    it "needs to be reviewed for spec completeness"
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/getbinaryfile.rb b/spec/ruby/library/net-ftp/shared/getbinaryfile.rb
new file mode 100644
index 0000000000..4fc4731c45
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/getbinaryfile.rb
@@ -0,0 +1,152 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_getbinaryfile, shared: true do
+    before :each do
+      @fixture_file = __dir__ + "/../fixtures/getbinaryfile"
+      @tmp_file = tmp("getbinaryfile")
+
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+      @ftp.binary = @binary_mode
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @tmp_file
+    end
+
+    it "sends the RETR command to the server" do
+      @ftp.send(@method, "test", @tmp_file)
+      @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
+    end
+
+    it "returns nil" do
+      @ftp.send(@method, "test", @tmp_file).should == nil
+    end
+
+    it "saves the contents of the passed remote file to the passed local file" do
+      @ftp.send(@method, "test", @tmp_file)
+      File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
+    end
+
+    describe "when passed a block" do
+      it "yields the received content as binary blocks of the passed size" do
+        res = []
+        @ftp.send(@method, "test", @tmp_file, 10) { |bin| res << bin }
+        res.should == [ "This is th", "e content\n", "of the fil", "e named 't", "est'.\n" ]
+      end
+    end
+
+    describe "when resuming an existing file" do
+      before :each do
+        @tmp_file = tmp("getbinaryfile_resume")
+
+        File.open(@tmp_file, "wb") do |f|
+          f << "This is the content\n"
+        end
+
+        @ftp.resume = true
+      end
+
+      it "saves the remaining content of the passed remote file to the passed local file" do
+        @ftp.send(@method, "test", @tmp_file)
+        File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
+      end
+
+      describe "and the REST command fails" do
+        it "raises a Net::FTPProtoError when the response code is 550" do
+          @server.should_receive(:rest).and_respond("Requested action not taken.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPProtoError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 500" do
+          @server.should_receive(:rest).and_respond("500 Syntax error, command unrecognized.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 501" do
+          @server.should_receive(:rest).and_respond("501 Syntax error, command unrecognized.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 502" do
+          @server.should_receive(:rest).and_respond("502 Command not implemented.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPTempError when the response code is 421" do
+          @server.should_receive(:rest).and_respond("421 Service not available, closing control connection.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 530" do
+          @server.should_receive(:rest).and_respond("530 Not logged in.")
+          -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+        end
+      end
+    end
+
+    describe "when the RETR command fails" do
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:retr).and_respond("450 Requested file action not taken.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPProtoError when the response code is 550" do
+        @server.should_receive(:retr).and_respond("Requested action not taken.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPProtoError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:retr).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:retr).and_respond("501 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:retr).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:retr).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/gettextfile.rb b/spec/ruby/library/net-ftp/shared/gettextfile.rb
new file mode 100644
index 0000000000..562c7a3047
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/gettextfile.rb
@@ -0,0 +1,102 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_gettextfile, shared: true do
+    before :each do
+      @tmp_file = tmp("gettextfile")
+
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+      @ftp.binary = @binary_mode
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @tmp_file
+    end
+
+    it "sends the RETR command to the server" do
+      @ftp.send(@method, "test", @tmp_file)
+      @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
+    end
+
+    it "returns nil" do
+      @ftp.send(@method, "test", @tmp_file).should == nil
+    end
+
+    it "saves the contents of the passed remote file to the passed local file" do
+      @ftp.send(@method, "test", @tmp_file)
+      File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
+    end
+
+    describe "when passed a block" do
+      it "yields each line of the retrieved file to the passed block" do
+        res = []
+        @ftp.send(@method, "test", @tmp_file) { |line| res << line }
+        res.should == [ "This is the content", "of the file named 'test'."]
+      end
+    end
+
+    describe "when the RETR command fails" do
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:retr).and_respond("450 Requested file action not taken.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPProtoError when the response code is 550" do
+        @server.should_receive(:retr).and_respond("Requested action not taken.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPProtoError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:retr).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:retr).and_respond("501 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:retr).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:retr).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, "test", @tmp_file) }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/last_response_code.rb b/spec/ruby/library/net-ftp/shared/last_response_code.rb
new file mode 100644
index 0000000000..9d36e37f0c
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/last_response_code.rb
@@ -0,0 +1,27 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_last_response_code, shared: true do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "returns the response code for the last response" do
+      @server.should_receive(:help).and_respond("200 Command okay.")
+      @ftp.help
+      @ftp.send(@method).should == "200"
+
+      @server.should_receive(:help).and_respond("212 Directory status.")
+      @ftp.help
+      @ftp.send(@method).should == "212"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/list.rb b/spec/ruby/library/net-ftp/shared/list.rb
new file mode 100644
index 0000000000..ec372447e8
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/list.rb
@@ -0,0 +1,106 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_list, shared: true do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.passive = false
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    describe "when passed a block" do
+      it "yields each file in the list of files in the passed dir" do
+        expected = [
+          "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
+          "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
+          "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
+        ]
+
+        res = []
+        @ftp.send(@method, "test.folder") { |line| res << line}
+        res.should == expected
+
+        @ftp.last_response.should == "226 transfer complete (LIST test.folder)\n"
+      end
+    end
+
+    describe "when passed no block" do
+      it "returns an Array containing a list of files in the passed dir" do
+        expected = [
+          "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
+          "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
+          "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
+        ]
+
+        @ftp.send(@method, "test.folder").should == expected
+
+        @ftp.last_response.should == "226 transfer complete (LIST test.folder)\n"
+      end
+    end
+
+    describe "when the LIST command fails" do
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:list).and_respond("450 Requested file action not taken..")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:list).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:list).and_respond("501 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 502" do
+        @server.should_receive(:list).and_respond("502 Command not implemented.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:list).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:list).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method) }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/putbinaryfile.rb b/spec/ruby/library/net-ftp/shared/putbinaryfile.rb
new file mode 100644
index 0000000000..afbe3c61f8
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/putbinaryfile.rb
@@ -0,0 +1,169 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_putbinaryfile, shared: true do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @local_fixture_file  = __dir__ + "/../fixtures/putbinaryfile"
+      @remote_tmp_file = tmp("binaryfile", false)
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+      @ftp.binary = @binary_mode
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @remote_tmp_file
+    end
+
+    it "sends the STOR command to the server" do
+      @ftp.send(@method, @local_fixture_file, "binary")
+      @ftp.last_response.should == "200 OK, Data received. (STOR binary)\n"
+    end
+
+    it "sends the contents of the passed local_file, without modifications" do
+      @ftp.send(@method, @local_fixture_file, "binary")
+
+      remote_lines = File.readlines(@remote_tmp_file)
+      local_lines  = File.readlines(@local_fixture_file)
+
+      remote_lines.should == local_lines
+    end
+
+    it "returns nil" do
+      @ftp.send(@method, @local_fixture_file, "binary").should == nil
+    end
+
+    describe "when passed a block" do
+      it "yields the transmitted content as binary blocks of the passed size" do
+        res = []
+        @ftp.send(@method, @local_fixture_file, "binary", 10) { |x| res << x }
+        res.should == [
+          "This is an", " example f",
+          "ile\nwhich ", "is going t",
+          "o be trans", "mitted\nusi",
+          "ng #putbin", "aryfile.\n"
+        ]
+      end
+    end
+
+    describe "when resuming an existing file" do
+      before :each do
+        File.open(@remote_tmp_file, "w") do |f|
+          f << "This is an example file\n"
+        end
+
+        @ftp.resume = true
+      end
+
+      it "sends the remaining content of the passed local_file to the passed remote_file" do
+        @ftp.send(@method, @local_fixture_file, "binary")
+        File.read(@remote_tmp_file).should == File.read(@local_fixture_file)
+      end
+
+      describe "and the APPE command fails" do
+        it "raises a Net::FTPProtoError when the response code is 550" do
+          @server.should_receive(:appe).and_respond("Requested action not taken.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPProtoError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 500" do
+          @server.should_receive(:appe).and_respond("500 Syntax error, command unrecognized.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 501" do
+          @server.should_receive(:appe).and_respond("501 Syntax error, command unrecognized.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 502" do
+          @server.should_receive(:appe).and_respond("502 Command not implemented.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+        end
+
+        it "raises a Net::FTPTempError when the response code is 421" do
+          @server.should_receive(:appe).and_respond("421 Service not available, closing control connection.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPTempError)
+        end
+
+        it "raises a Net::FTPPermError when the response code is 530" do
+          @server.should_receive(:appe).and_respond("530 Not logged in.")
+          -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+        end
+      end
+    end
+
+    describe "when the STOR command fails" do
+      it "raises a Net::FTPPermError when the response code is 532" do
+        @server.should_receive(:stor).and_respond("532 Need account for storing files.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:stor).and_respond("450 Requested file action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 452" do
+        @server.should_receive(:stor).and_respond("452 Requested action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 553" do
+        @server.should_receive(:stor).and_respond("553 Requested action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:stor).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:stor).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:stor).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:stor).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/puttextfile.rb b/spec/ruby/library/net-ftp/shared/puttextfile.rb
new file mode 100644
index 0000000000..3650cad230
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/puttextfile.rb
@@ -0,0 +1,130 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_puttextfile, shared: true do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @local_fixture_file  = __dir__ + "/../fixtures/puttextfile"
+      @remote_tmp_file = tmp("textfile", false)
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+      @ftp.binary = @binary_mode
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @remote_tmp_file
+    end
+
+    it "sends the STOR command to the server" do
+      @ftp.send(@method, @local_fixture_file, "text")
+      @ftp.last_response.should == "200 OK, Data received. (STOR text)\n"
+    end
+
+    it "sends the contents of the passed local_file, using \\r\\n as the newline separator" do
+      @ftp.send(@method, @local_fixture_file, "text")
+
+      remote_lines = File.binread(@remote_tmp_file)
+      local_lines  = File.binread(@local_fixture_file)
+
+      remote_lines.should_not == local_lines
+      remote_lines.should == local_lines.gsub("\n", "\r\n")
+    end
+
+    guard -> { Net::FTP::VERSION < '0.3.6' } do
+      it "returns nil" do
+        @ftp.send(@method, @local_fixture_file, "text").should == nil
+      end
+    end
+
+    guard -> { Net::FTP::VERSION >= '0.3.6' } do
+      it "returns the response" do
+        @ftp.send(@method, @local_fixture_file, "text").should == @ftp.last_response
+      end
+    end
+
+    describe "when passed a block" do
+      it "yields each transmitted line" do
+        res = []
+        @ftp.send(@method, @local_fixture_file, "text") { |x| res << x }
+        res.should == [
+          "This is an example file\r\n",
+          "which is going to be transmitted\r\n",
+          "using #puttextfile.\r\n"
+        ]
+      end
+    end
+
+    describe "when the STOR command fails" do
+      it "raises a Net::FTPPermError when the response code is 532" do
+        @server.should_receive(:stor).and_respond("532 Need account for storing files.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 450" do
+        @server.should_receive(:stor).and_respond("450 Requested file action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 452" do
+        @server.should_receive(:stor).and_respond("452 Requested action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 553" do
+        @server.should_receive(:stor).and_respond("553 Requested action not taken.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:stor).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:stor).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:stor).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:stor).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+    end
+
+    describe "when opening the data port fails" do
+      it "raises a Net::FTPPermError when the response code is 500" do
+        @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
+        @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 501" do
+        @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
+        @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+
+      it "raises a Net::FTPTempError when the response code is 421" do
+        @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
+        @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPTempError)
+      end
+
+      it "raises a Net::FTPPermError when the response code is 530" do
+        @server.should_receive(:eprt).and_respond("530 Not logged in.")
+        @server.should_receive(:port).and_respond("530 Not logged in.")
+        -> { @ftp.send(@method, @local_fixture_file, "text") }.should.raise(Net::FTPPermError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/shared/pwd.rb b/spec/ruby/library/net-ftp/shared/pwd.rb
new file mode 100644
index 0000000000..db3e587464
--- /dev/null
+++ b/spec/ruby/library/net-ftp/shared/pwd.rb
@@ -0,0 +1,5 @@
+ruby_version_is ""..."4.1" do
+  describe :net_ftp_pwd, shared: true do
+
+  end
+end
diff --git a/spec/ruby/library/net-ftp/site_spec.rb b/spec/ruby/library/net-ftp/site_spec.rb
new file mode 100644
index 0000000000..adc7dfafdf
--- /dev/null
+++ b/spec/ruby/library/net-ftp/site_spec.rb
@@ -0,0 +1,56 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#site" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the SITE command with the passed argument to the server" do
+      @ftp.site("param")
+      @ftp.last_response.should == "200 Command okay. (SITE param)\n"
+    end
+
+    it "returns nil" do
+      @ftp.site("param").should == nil
+    end
+
+    it "does not raise an error when the response code is 202" do
+      @server.should_receive(:site).and_respond("202 Command not implemented, superfluous at this site.")
+      -> { @ftp.site("param") }.should_not.raise
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:site).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.site("param") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:site).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.site("param") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:site).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.site("param") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:site).and_respond("530 Requested action not taken.")
+      -> { @ftp.site("param") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/size_spec.rb b/spec/ruby/library/net-ftp/size_spec.rb
new file mode 100644
index 0000000000..dd84e5a449
--- /dev/null
+++ b/spec/ruby/library/net-ftp/size_spec.rb
@@ -0,0 +1,51 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#size" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the SIZE command to the server" do
+      @ftp.size("test.file")
+      @ftp.last_response.should == "213 1024\n"
+    end
+
+    it "returns the size of the passed file as Integer" do
+      @ftp.size("test.file").should.eql?(1024)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:size).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.size("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:size).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.size("test.file") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:size).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.size("test.file") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 550" do
+      @server.should_receive(:size).and_respond("550 Requested action not taken.")
+      -> { @ftp.size("test.file") }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/spec_helper.rb b/spec/ruby/library/net-ftp/spec_helper.rb
new file mode 100644
index 0000000000..7689b4fb0c
--- /dev/null
+++ b/spec/ruby/library/net-ftp/spec_helper.rb
@@ -0,0 +1,7 @@
+ruby_version_is ""..."4.1" do
+  require "net/ftp"
+
+  if defined?(Net::FTP.default_passive)
+    Net::FTP.default_passive = false
+  end
+end
diff --git a/spec/ruby/library/net-ftp/status_spec.rb b/spec/ruby/library/net-ftp/status_spec.rb
new file mode 100644
index 0000000000..ce29e215d4
--- /dev/null
+++ b/spec/ruby/library/net-ftp/status_spec.rb
@@ -0,0 +1,70 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#status" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the STAT command to the server" do
+      @ftp.status
+      @ftp.last_response.should == "211 System status, or system help reply. (STAT)\n"
+    end
+
+    it "sends the STAT command with an optional parameter to the server" do
+      @ftp.status("/pub").should == "211 System status, or system help reply. (STAT /pub)\n"
+    end
+
+    it "returns the received information" do
+      @ftp.status.should == "211 System status, or system help reply. (STAT)\n"
+    end
+
+    it "does not raise an error when the response code is 212" do
+      @server.should_receive(:stat).and_respond("212 Directory status.")
+      -> { @ftp.status }.should_not.raise
+    end
+
+    it "does not raise an error when the response code is 213" do
+      @server.should_receive(:stat).and_respond("213 File status.")
+      -> { @ftp.status }.should_not.raise
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:stat).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.status }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:stat).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.status }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:stat).and_respond("502 Command not implemented.")
+      -> { @ftp.status }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:stat).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.status }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 530" do
+      @server.should_receive(:stat).and_respond("530 Requested action not taken.")
+      -> { @ftp.status }.should.raise(Net::FTPPermError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/storbinary_spec.rb b/spec/ruby/library/net-ftp/storbinary_spec.rb
new file mode 100644
index 0000000000..a2f81fc669
--- /dev/null
+++ b/spec/ruby/library/net-ftp/storbinary_spec.rb
@@ -0,0 +1,52 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#storbinary" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @local_fixture_file  = __dir__ + "/fixtures/putbinaryfile"
+      @tmp_file = tmp("binaryfile", false)
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @tmp_file
+    end
+
+    it "sends the passed command and the passed File object's content to the server" do
+      File.open(@local_fixture_file) do |f|
+        f.binmode
+
+        @ftp.storbinary("STOR binary", f, 4096) {}
+        @ftp.last_response.should == "200 OK, Data received. (STOR binary)\n"
+      end
+    end
+
+    it "yields the transmitted content as binary blocks of the passed size" do
+      File.open(@local_fixture_file) do |f|
+        f.binmode
+
+        res = []
+        @ftp.storbinary("STOR binary", f, 10) { |x| res << x }
+        res.should == [
+          "This is an", " example f",
+          "ile\nwhich ", "is going t",
+          "o be trans", "mitted\nusi",
+          "ng #putbin", "aryfile.\n"
+        ]
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/storlines_spec.rb b/spec/ruby/library/net-ftp/storlines_spec.rb
new file mode 100644
index 0000000000..09340bafe9
--- /dev/null
+++ b/spec/ruby/library/net-ftp/storlines_spec.rb
@@ -0,0 +1,47 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#storlines" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @local_fixture_file  = __dir__ + "/fixtures/puttextfile"
+      @tmp_file = tmp("textfile", false)
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+
+      rm_r @tmp_file
+    end
+
+    it "sends the passed command and the passed File object's content to the server" do
+      File.open(@local_fixture_file) do |f|
+        @ftp.storlines("STOR text", f) {}
+        @ftp.last_response.should == "200 OK, Data received. (STOR text)\n"
+      end
+    end
+
+    it "yields each line of the transmitted content" do
+      File.open(@local_fixture_file) do |f|
+        res = []
+        @ftp.storlines("STOR text", f) { |x| res << x }
+        res.should == [
+          "This is an example file\r\n",
+          "which is going to be transmitted\r\n",
+          "using #puttextfile.\r\n"
+        ]
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/system_spec.rb b/spec/ruby/library/net-ftp/system_spec.rb
new file mode 100644
index 0000000000..fa61776282
--- /dev/null
+++ b/spec/ruby/library/net-ftp/system_spec.rb
@@ -0,0 +1,51 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#system" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the SYST command to the server" do
+      @ftp.system
+      @ftp.last_response.should =~ /\A215 FTP Dummy Server \(SYST\)\Z/
+    end
+
+    it "returns the received information" do
+      @ftp.system.should =~ /\AFTP Dummy Server \(SYST\)\Z/
+    end
+
+    it "raises a Net::FTPPermError when the response code is 500" do
+      @server.should_receive(:syst).and_respond("500 Syntax error, command unrecognized.")
+      -> { @ftp.system }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 501" do
+      @server.should_receive(:syst).and_respond("501 Syntax error in parameters or arguments.")
+      -> { @ftp.system }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 502" do
+      @server.should_receive(:syst).and_respond("502 Command not implemented.")
+      -> { @ftp.system }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 421" do
+      @server.should_receive(:syst).and_respond("421 Service not available, closing control connection.")
+      -> { @ftp.system }.should.raise(Net::FTPTempError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/voidcmd_spec.rb b/spec/ruby/library/net-ftp/voidcmd_spec.rb
new file mode 100644
index 0000000000..4f74da7a70
--- /dev/null
+++ b/spec/ruby/library/net-ftp/voidcmd_spec.rb
@@ -0,0 +1,57 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#voidcmd" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "sends the passed command to the server" do
+      @server.should_receive(:help).and_respond("2xx Does not raise.")
+      -> { @ftp.voidcmd("HELP") }.should_not.raise
+    end
+
+    it "returns nil" do
+      @server.should_receive(:help).and_respond("2xx Does not raise.")
+      @ftp.voidcmd("HELP").should == nil
+    end
+
+    it "raises a Net::FTPReplyError when the response code is 1xx" do
+      @server.should_receive(:help).and_respond("1xx Does raise a Net::FTPReplyError.")
+      -> { @ftp.voidcmd("HELP")  }.should.raise(Net::FTPReplyError)
+    end
+
+    it "raises a Net::FTPReplyError when the response code is 3xx" do
+      @server.should_receive(:help).and_respond("3xx Does raise a Net::FTPReplyError.")
+      -> { @ftp.voidcmd("HELP") }.should.raise(Net::FTPReplyError)
+    end
+
+    it "raises a Net::FTPTempError when the response code is 4xx" do
+      @server.should_receive(:help).and_respond("4xx Does raise a Net::FTPTempError.")
+      -> { @ftp.voidcmd("HELP") }.should.raise(Net::FTPTempError)
+    end
+
+    it "raises a Net::FTPPermError when the response code is 5xx" do
+      @server.should_receive(:help).and_respond("5xx Does raise a Net::FTPPermError.")
+      -> { @ftp.voidcmd("HELP") }.should.raise(Net::FTPPermError)
+    end
+
+    it "raises a Net::FTPProtoError when the response code is not valid" do
+      @server.should_receive(:help).and_respond("999 Does raise a Net::FTPProtoError.")
+      -> { @ftp.voidcmd("HELP") }.should.raise(Net::FTPProtoError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-ftp/welcome_spec.rb b/spec/ruby/library/net-ftp/welcome_spec.rb
new file mode 100644
index 0000000000..761a0f9a3e
--- /dev/null
+++ b/spec/ruby/library/net-ftp/welcome_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."4.1" do
+  require_relative 'spec_helper'
+  require_relative 'fixtures/server'
+
+  describe "Net::FTP#welcome" do
+    before :each do
+      @server = NetFTPSpecs::DummyFTP.new
+      @server.serve_once
+
+      @ftp = Net::FTP.new
+      @ftp.connect(@server.hostname, @server.server_port)
+    end
+
+    after :each do
+      @ftp.quit rescue nil
+      @ftp.close
+      @server.stop
+    end
+
+    it "returns the server's welcome message" do
+      @ftp.welcome.should == nil
+      @ftp.login
+      @ftp.welcome.should == "230 User logged in, proceed. (USER anonymous)\n"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPBadResponse_spec.rb b/spec/ruby/library/net-http/HTTPBadResponse_spec.rb
new file mode 100644
index 0000000000..8f2e8ccfaf
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPBadResponse_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPBadResponse" do
+  it "is a subclass of StandardError" do
+    Net::HTTPBadResponse.should < StandardError
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPClientExcepton_spec.rb b/spec/ruby/library/net-http/HTTPClientExcepton_spec.rb
new file mode 100644
index 0000000000..2992e6596f
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPClientExcepton_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPClientException" do
+  it "is a subclass of Net::ProtoServerError" do
+    Net::HTTPClientException.should < Net::ProtoServerError
+  end
+
+  it "includes the Net::HTTPExceptions module" do
+    Net::HTTPClientException.should < Net::HTTPExceptions
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPError_spec.rb b/spec/ruby/library/net-http/HTTPError_spec.rb
new file mode 100644
index 0000000000..7f79eef8cf
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPError_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPError" do
+  it "is a subclass of Net::ProtocolError" do
+    Net::HTTPError.should < Net::ProtocolError
+  end
+
+  it "includes the Net::HTTPExceptions module" do
+    Net::HTTPError.should < Net::HTTPExceptions
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPFatalError_spec.rb b/spec/ruby/library/net-http/HTTPFatalError_spec.rb
new file mode 100644
index 0000000000..0113b9da2d
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPFatalError_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPFatalError" do
+  it "is a subclass of Net::ProtoFatalError" do
+    Net::HTTPFatalError.should < Net::ProtoFatalError
+  end
+
+  it "includes the Net::HTTPExceptions module" do
+    Net::HTTPFatalError.should < Net::HTTPExceptions
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPHeaderSyntaxError_spec.rb b/spec/ruby/library/net-http/HTTPHeaderSyntaxError_spec.rb
new file mode 100644
index 0000000000..b3b73ff46f
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPHeaderSyntaxError_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPHeaderSyntaxError" do
+  it "is a subclass of StandardError" do
+    Net::HTTPHeaderSyntaxError.should < StandardError
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPRetriableError_spec.rb b/spec/ruby/library/net-http/HTTPRetriableError_spec.rb
new file mode 100644
index 0000000000..677731fb68
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPRetriableError_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPRetriableError" do
+  it "is a subclass of Net::ProtoRetriableError" do
+    Net::HTTPRetriableError.should < Net::ProtoRetriableError
+  end
+
+  it "includes the Net::HTTPExceptions module" do
+    Net::HTTPRetriableError.should < Net::HTTPExceptions
+  end
+end
diff --git a/spec/ruby/library/net-http/HTTPServerException_spec.rb b/spec/ruby/library/net-http/HTTPServerException_spec.rb
new file mode 100644
index 0000000000..020d3cce85
--- /dev/null
+++ b/spec/ruby/library/net-http/HTTPServerException_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPServerException" do
+  it "is a subclass of Net::ProtoServerError and is warned as deprecated" do
+    -> { eval("Net::HTTPServerException").should < Net::ProtoServerError }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
+  end
+
+  it "includes the Net::HTTPExceptions module and is warned as deprecated" do
+    -> { eval("Net::HTTPServerException").should < Net::HTTPExceptions }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/Proxy_spec.rb b/spec/ruby/library/net-http/http/Proxy_spec.rb
new file mode 100644
index 0000000000..7753ce5e30
--- /dev/null
+++ b/spec/ruby/library/net-http/http/Proxy_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.Proxy" do
+  it "returns a new subclass of Net::HTTP" do
+    Net::HTTP.Proxy("localhost").should < Net::HTTP
+  end
+
+  it "returns Net::HTTP when the passed address is nil" do
+    Net::HTTP.Proxy(nil).should == Net::HTTP
+  end
+
+  it "sets the returned subclasses' proxy options based on the passed arguments" do
+    http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+    http_with_proxy.proxy_address.should == "localhost"
+    http_with_proxy.proxy_port.should.eql?(1234)
+    http_with_proxy.proxy_user.should == "rspec"
+    http_with_proxy.proxy_pass.should == "rocks"
+  end
+end
+
+describe "Net::HTTP#proxy?" do
+  describe "when self is no proxy class instance" do
+    it "returns false" do
+      Net::HTTP.new("localhost", 3333).proxy?.should == false
+    end
+  end
+
+  describe "when self is a proxy class instance" do
+    it "returns false" do
+      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+      http_with_proxy.new("localhost", 3333).proxy?.should == true
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/active_spec.rb b/spec/ruby/library/net-http/http/active_spec.rb
new file mode 100644
index 0000000000..c260274594
--- /dev/null
+++ b/spec/ruby/library/net-http/http/active_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/started'
+
+describe "Net::HTTP#active?" do
+  it_behaves_like :net_http_started_p, :active?
+end
diff --git a/spec/ruby/library/net-http/http/address_spec.rb b/spec/ruby/library/net-http/http/address_spec.rb
new file mode 100644
index 0000000000..7c5b82a8f9
--- /dev/null
+++ b/spec/ruby/library/net-http/http/address_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#address" do
+  it "returns the current host name" do
+    net = Net::HTTP.new("localhost")
+    net.address.should == "localhost"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/close_on_empty_response_spec.rb b/spec/ruby/library/net-http/http/close_on_empty_response_spec.rb
new file mode 100644
index 0000000000..9cc756befb
--- /dev/null
+++ b/spec/ruby/library/net-http/http/close_on_empty_response_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#close_on_empty_response" do
+  it "needs to be reviewed for spec completeness"
+end
+
+describe "Net::HTTP#close_on_empty_response=" do
+  it "needs to be reviewed for spec completeness"
+end
diff --git a/spec/ruby/library/net-http/http/copy_spec.rb b/spec/ruby/library/net-http/http/copy_spec.rb
new file mode 100644
index 0000000000..1f3e25009f
--- /dev/null
+++ b/spec/ruby/library/net-http/http/copy_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#copy" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a COPY request to the passed path and returns the response" do
+    response = @http.copy("/request")
+    response.should.is_a?(Net::HTTPResponse)
+    response.body.should == "Request type: COPY"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/default_port_spec.rb b/spec/ruby/library/net-http/http/default_port_spec.rb
new file mode 100644
index 0000000000..20407d0b12
--- /dev/null
+++ b/spec/ruby/library/net-http/http/default_port_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.default_port" do
+  it "returns 80" do
+    Net::HTTP.http_default_port.should.eql?(80)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/delete_spec.rb b/spec/ruby/library/net-http/http/delete_spec.rb
new file mode 100644
index 0000000000..09ddd74000
--- /dev/null
+++ b/spec/ruby/library/net-http/http/delete_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#delete" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a DELETE request to the passed path and returns the response" do
+    response = @http.delete("/request")
+    response.should.is_a?(Net::HTTPResponse)
+    response.body.should == "Request type: DELETE"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/finish_spec.rb b/spec/ruby/library/net-http/http/finish_spec.rb
new file mode 100644
index 0000000000..0d466675f3
--- /dev/null
+++ b/spec/ruby/library/net-http/http/finish_spec.rb
@@ -0,0 +1,29 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#finish" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when self has been started" do
+    it "closes the tcp connection" do
+      @http.start
+      @http.finish
+      @http.started?.should == false
+    end
+  end
+
+  describe "when self has not been started yet" do
+    it "raises an IOError" do
+      -> { @http.finish }.should.raise(IOError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/fixtures/http_server.rb b/spec/ruby/library/net-http/http/fixtures/http_server.rb
new file mode 100644
index 0000000000..c1cedbfa76
--- /dev/null
+++ b/spec/ruby/library/net-http/http/fixtures/http_server.rb
@@ -0,0 +1,123 @@
+require 'socket'
+
+module NetHTTPSpecs
+  class NullWriter
+    def <<(s) end
+    def puts(*args) end
+    def print(*args) end
+    def printf(*args) end
+  end
+
+  class SmallHTTPServer
+    def initialize(bind_address)
+      @server = TCPServer.new(bind_address, 0)
+      @thread = Thread.new {
+        Thread.current.abort_on_exception = true
+        listen
+      }
+    end
+
+    def ip
+      @server.addr[3]
+    end
+
+    def port
+      @server.addr[1]
+    end
+
+    def listen
+      until @server.closed?
+        client = @server.accept
+        handle_client(client)
+      end
+    end
+
+    def handle_client(client)
+      begin
+        until client.closed?
+          request = client.gets("\r\n\r\n")
+          break unless request
+          if request == "CLOSE"
+            @server.close
+            break
+          end
+          handle_request(client, request)
+        end
+      ensure
+        client.close
+      end
+    end
+
+    def parse_request(request)
+      request, *headers = request.chomp.lines.map { |line| line.chomp }
+      request_method, request_uri, _http_version = request.split
+      headers = headers.map { |line| line.split(': ', 2) }.to_h
+      [request_method, request_uri, headers]
+    end
+
+    def handle_request(client, request)
+      request_method, request_uri, headers = parse_request(request)
+
+      if headers.include? 'Content-Length'
+        request_body_size = Integer(headers['Content-Length'])
+        request_body = client.read(request_body_size)
+      end
+
+      case request_uri
+      when '/'
+        raise request_method unless request_method == 'GET'
+        reply(client, "This is the index page.", request_method)
+      when '/request'
+        reply(client, "Request type: #{request_method}", request_method)
+      when '/request/body'
+        reply(client, request_body, request_method)
+      when '/request/header'
+        reply(client, headers.inspect, request_method)
+      when '/request/basic_auth'
+        reply(client, "username: \npassword: ", request_method)
+      else
+        raise request_uri
+      end
+    end
+
+    def reply(client, body, request_method)
+      client.print "HTTP/1.1 200 OK\r\n"
+      if request_method == 'HEAD'
+        client.close
+      else
+        client.print "Content-Type: text/plain\r\n"
+        client.print "Content-Length: #{body.bytesize}\r\n"
+        client.print "\r\n"
+        client.print body
+      end
+    end
+
+    def close
+      TCPSocket.open(ip, port) do |socket|
+        socket.write "CLOSE"
+      end
+      @thread.join
+    end
+  end
+
+  @server = nil
+
+  class << self
+    def port
+      raise "server not started" unless @server
+      @server.port
+    end
+
+    def start_server
+      bind_address = platform_is(:windows) ? "localhost" : "127.0.0.1"
+      @server = SmallHTTPServer.new(bind_address)
+    end
+
+    def stop_server
+      if @server
+        @server.close
+        @server = nil
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/get2_spec.rb b/spec/ruby/library/net-http/http/get2_spec.rb
new file mode 100644
index 0000000000..57c05ec64b
--- /dev/null
+++ b/spec/ruby/library/net-http/http/get2_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_get'
+
+describe "Net::HTTP#get2" do
+  it_behaves_like :net_http_request_get, :get2
+end
diff --git a/spec/ruby/library/net-http/http/get_print_spec.rb b/spec/ruby/library/net-http/http/get_print_spec.rb
new file mode 100644
index 0000000000..3c24ce44ea
--- /dev/null
+++ b/spec/ruby/library/net-http/http/get_print_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.get_print" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed URI" do
+    it "it prints the body of the specified uri to $stdout" do
+      -> do
+        Net::HTTP.get_print URI.parse("http://localhost:#{@port}/")
+      end.should output(/This is the index page\./)
+    end
+  end
+
+  describe "when passed host, path, port" do
+    it "it prints the body of the specified uri to $stdout" do
+      -> do
+        Net::HTTP.get_print 'localhost', "/", @port
+      end.should output(/This is the index page\./)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/get_response_spec.rb b/spec/ruby/library/net-http/http/get_response_spec.rb
new file mode 100644
index 0000000000..7133ef8101
--- /dev/null
+++ b/spec/ruby/library/net-http/http/get_response_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.get_response" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed URI" do
+    it "returns the response for the specified uri" do
+      res = Net::HTTP.get_response(URI.parse("http://localhost:#{@port}/"))
+      res.content_type.should == "text/plain"
+      res.body.should == "This is the index page."
+    end
+  end
+
+  describe "when passed host, path, port" do
+    it "returns the response for the specified host-path-combination" do
+      res = Net::HTTP.get_response('localhost', "/", @port)
+      res.content_type.should == "text/plain"
+      res.body.should == "This is the index page."
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/get_spec.rb b/spec/ruby/library/net-http/http/get_spec.rb
new file mode 100644
index 0000000000..9be726dc3b
--- /dev/null
+++ b/spec/ruby/library/net-http/http/get_spec.rb
@@ -0,0 +1,94 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.get" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed URI" do
+    it "returns the body of the specified uri" do
+      Net::HTTP.get(URI.parse("http://localhost:#{@port}/")).should == "This is the index page."
+    end
+  end
+
+  describe "when passed host, path, port" do
+    it "returns the body of the specified host-path-combination" do
+      Net::HTTP.get('localhost', "/", @port).should == "This is the index page."
+    end
+  end
+end
+
+quarantine! do # These specs fail frequently with CHECK_LEAKS=true
+describe "Net::HTTP.get" do
+  describe "when reading gzipped contents" do
+    def start_threads
+      require 'zlib'
+      require 'stringio'
+
+      server = nil
+      server_thread = Thread.new do
+        server = TCPServer.new("127.0.0.1", 0)
+        begin
+          c = server.accept
+        ensure
+          server.close
+        end
+        c.print "HTTP/1.1 200\r\n"
+        c.print "Content-Type: text/plain\r\n"
+        c.print "Content-Encoding: gzip\r\n"
+        s = StringIO.new
+        z = Zlib::GzipWriter.new(s)
+        begin
+          z.write 'Hello World!'
+        ensure
+          z.close
+        end
+        c.print "Content-Length: #{s.length}\r\n\r\n"
+        # Write partial gzip content
+        c.write s.string.byteslice(0..-2)
+        c.flush
+        c
+      end
+      Thread.pass until server && server_thread.stop?
+
+      client_thread = Thread.new do
+        Thread.current.report_on_exception = false
+        Net::HTTP.get("127.0.0.1", '/', server.connect_address.ip_port)
+      end
+
+      socket = server_thread.value
+      Thread.pass until client_thread.stop?
+
+      [socket, client_thread]
+    end
+
+    it "propagates exceptions interrupting the thread and does not replace it with Zlib::BufError" do
+      my_exception = Class.new(RuntimeError)
+      socket, client_thread = start_threads
+      begin
+        client_thread.raise my_exception, "my exception"
+        -> { client_thread.value }.should.raise(my_exception)
+      ensure
+        socket.close
+      end
+    end
+
+    it "lets the kill Thread exception goes through and does not replace it with Zlib::BufError" do
+      socket, client_thread = start_threads
+      begin
+        client_thread.kill
+        client_thread.value.should == nil
+      ensure
+        socket.close
+      end
+    end
+  end
+end
+end
diff --git a/spec/ruby/library/net-http/http/head2_spec.rb b/spec/ruby/library/net-http/http/head2_spec.rb
new file mode 100644
index 0000000000..84cfff33d7
--- /dev/null
+++ b/spec/ruby/library/net-http/http/head2_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_head'
+
+describe "Net::HTTP#head2" do
+  it_behaves_like :net_http_request_head, :head2
+end
diff --git a/spec/ruby/library/net-http/http/head_spec.rb b/spec/ruby/library/net-http/http/head_spec.rb
new file mode 100644
index 0000000000..4824d22534
--- /dev/null
+++ b/spec/ruby/library/net-http/http/head_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#head" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a HEAD request to the passed path and returns the response" do
+    response = @http.head("/request")
+    # HEAD requests have no responses
+    response.body.should == nil
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.head("/request").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/http_default_port_spec.rb b/spec/ruby/library/net-http/http/http_default_port_spec.rb
new file mode 100644
index 0000000000..82c88e58a8
--- /dev/null
+++ b/spec/ruby/library/net-http/http/http_default_port_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.http_default_port" do
+  it "returns 80" do
+    Net::HTTP.http_default_port.should.eql?(80)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/https_default_port_spec.rb b/spec/ruby/library/net-http/http/https_default_port_spec.rb
new file mode 100644
index 0000000000..24b9c3b462
--- /dev/null
+++ b/spec/ruby/library/net-http/http/https_default_port_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.https_default_port" do
+  it "returns 443" do
+    Net::HTTP.https_default_port.should.eql?(443)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/initialize_spec.rb b/spec/ruby/library/net-http/http/initialize_spec.rb
new file mode 100644
index 0000000000..907314cb25
--- /dev/null
+++ b/spec/ruby/library/net-http/http/initialize_spec.rb
@@ -0,0 +1,46 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#initialize" do
+  it "is private" do
+    Net::HTTP.private_instance_methods(false).should.include?(:initialize)
+  end
+
+  describe "when passed address" do
+    before :each do
+      @net = Net::HTTP.allocate
+      @net.send(:initialize, "localhost")
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @net.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the default HTTP port" do
+      @net.port.should.eql?(Net::HTTP.default_port)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @net.started?.should == false
+    end
+  end
+
+  describe "when passed address, port" do
+    before :each do
+      @net = Net::HTTP.allocate
+      @net.send(:initialize, "localhost", 3333)
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @net.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the passed port" do
+      @net.port.should.eql?(3333)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @net.started?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/inspect_spec.rb b/spec/ruby/library/net-http/http/inspect_spec.rb
new file mode 100644
index 0000000000..fd4e6116c7
--- /dev/null
+++ b/spec/ruby/library/net-http/http/inspect_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#inspect" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+    @http = Net::HTTP.new("localhost", @port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "returns a String representation of self" do
+    @http.inspect.should.is_a?(String)
+    @http.inspect.should == "#<Net::HTTP localhost:#{@port} open=false>"
+
+    @http.start
+    @http.inspect.should == "#<Net::HTTP localhost:#{@port} open=true>"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/is_version_1_1_spec.rb b/spec/ruby/library/net-http/http/is_version_1_1_spec.rb
new file mode 100644
index 0000000000..bdb343f9e0
--- /dev/null
+++ b/spec/ruby/library/net-http/http/is_version_1_1_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/version_1_1'
+
+describe "Net::HTTP.is_version_1_1?" do
+  it_behaves_like :net_http_version_1_1_p, :is_version_1_1?
+end
diff --git a/spec/ruby/library/net-http/http/is_version_1_2_spec.rb b/spec/ruby/library/net-http/http/is_version_1_2_spec.rb
new file mode 100644
index 0000000000..555bb205dd
--- /dev/null
+++ b/spec/ruby/library/net-http/http/is_version_1_2_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/version_1_2'
+
+describe "Net::HTTP.is_version_1_2?" do
+  it_behaves_like :net_http_version_1_2_p, :is_version_1_2?
+end
diff --git a/spec/ruby/library/net-http/http/lock_spec.rb b/spec/ruby/library/net-http/http/lock_spec.rb
new file mode 100644
index 0000000000..12df138ad0
--- /dev/null
+++ b/spec/ruby/library/net-http/http/lock_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#lock" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a LOCK request to the passed path and returns the response" do
+    response = @http.lock("/request", "test=test")
+    response.should.is_a?(Net::HTTPResponse)
+    response.body.should == "Request type: LOCK"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/mkcol_spec.rb b/spec/ruby/library/net-http/http/mkcol_spec.rb
new file mode 100644
index 0000000000..b1a5055982
--- /dev/null
+++ b/spec/ruby/library/net-http/http/mkcol_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#mkcol" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a MKCOL request to the passed path and returns the response" do
+    response = @http.mkcol("/request")
+    response.should.is_a?(Net::HTTPResponse)
+    response.body.should == "Request type: MKCOL"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/move_spec.rb b/spec/ruby/library/net-http/http/move_spec.rb
new file mode 100644
index 0000000000..a57c2a0f49
--- /dev/null
+++ b/spec/ruby/library/net-http/http/move_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#head" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a MOVE request to the passed path and returns the response" do
+    response = @http.move("/request")
+    # HEAD requests have no responses
+    response.body.should == "Request type: MOVE"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.move("/request").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/new_spec.rb b/spec/ruby/library/net-http/http/new_spec.rb
new file mode 100644
index 0000000000..8feb3d1351
--- /dev/null
+++ b/spec/ruby/library/net-http/http/new_spec.rb
@@ -0,0 +1,86 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.new" do
+  describe "when passed address" do
+    before :each do
+      @http = Net::HTTP.new("localhost")
+    end
+
+    it "returns a Net::HTTP instance" do
+      @http.proxy?.should == false
+      @http.instance_of?(Net::HTTP).should == true
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @http.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the default HTTP port" do
+      @http.port.should.eql?(Net::HTTP.default_port)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @http.started?.should == false
+    end
+  end
+
+  describe "when passed address, port" do
+    before :each do
+      @http = Net::HTTP.new("localhost", 3333)
+    end
+
+    it "returns a Net::HTTP instance" do
+      @http.proxy?.should == false
+      @http.instance_of?(Net::HTTP).should == true
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @http.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the passed port" do
+      @http.port.should.eql?(3333)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @http.started?.should == false
+    end
+  end
+
+  describe "when passed address, port, *proxy_options" do
+    it "returns a Net::HTTP instance" do
+      http = Net::HTTP.new("localhost", 3333, "localhost")
+      http.proxy?.should == true
+      http.instance_of?(Net::HTTP).should == true
+      http.should.is_a?(Net::HTTP)
+    end
+
+    it "correctly sets the passed Proxy options" do
+      http = Net::HTTP.new("localhost", 3333, "localhost")
+      http.proxy_address.should == "localhost"
+      http.proxy_port.should.eql?(80)
+      http.proxy_user.should == nil
+      http.proxy_pass.should == nil
+
+      http = Net::HTTP.new("localhost", 3333, "localhost", 1234)
+      http.proxy_address.should == "localhost"
+      http.proxy_port.should.eql?(1234)
+      http.proxy_user.should == nil
+      http.proxy_pass.should == nil
+
+      http = Net::HTTP.new("localhost", 3333, "localhost", 1234, "rubyspec")
+      http.proxy_address.should == "localhost"
+      http.proxy_port.should.eql?(1234)
+      http.proxy_user.should == "rubyspec"
+      http.proxy_pass.should == nil
+
+      http = Net::HTTP.new("localhost", 3333, "localhost", 1234, "rubyspec", "rocks")
+      http.proxy_address.should == "localhost"
+      http.proxy_port.should.eql?(1234)
+      http.proxy_user.should == "rubyspec"
+      http.proxy_pass.should == "rocks"
+    end
+  end
+
+end
diff --git a/spec/ruby/library/net-http/http/newobj_spec.rb b/spec/ruby/library/net-http/http/newobj_spec.rb
new file mode 100644
index 0000000000..d398fb7d9a
--- /dev/null
+++ b/spec/ruby/library/net-http/http/newobj_spec.rb
@@ -0,0 +1,48 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.newobj" do
+  before :each do
+    @net = Net::HTTP.newobj("localhost")
+  end
+
+  describe "when passed address" do
+    it "returns a new Net::HTTP instance" do
+      @net.should.is_a?(Net::HTTP)
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @net.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the default HTTP port" do
+      @net.port.should.eql?(Net::HTTP.default_port)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @net.started?.should == false
+    end
+  end
+
+  describe "when passed address, port" do
+    before :each do
+      @net = Net::HTTP.newobj("localhost", 3333)
+    end
+
+    it "returns a new Net::HTTP instance" do
+      @net.should.is_a?(Net::HTTP)
+    end
+
+    it "sets the new Net::HTTP instance's address to the passed address" do
+      @net.address.should == "localhost"
+    end
+
+    it "sets the new Net::HTTP instance's port to the passed port" do
+      @net.port.should.eql?(3333)
+    end
+
+    it "does not start the new Net::HTTP instance" do
+      @net.started?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/open_timeout_spec.rb b/spec/ruby/library/net-http/http/open_timeout_spec.rb
new file mode 100644
index 0000000000..d00f844b38
--- /dev/null
+++ b/spec/ruby/library/net-http/http/open_timeout_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#open_timeout" do
+  it "returns the seconds to wait till the connection is open" do
+    net = Net::HTTP.new("localhost")
+    net.open_timeout.should.eql?(60)
+    net.open_timeout = 10
+    net.open_timeout.should.eql?(10)
+  end
+end
+
+describe "Net::HTTP#open_timeout=" do
+  it "sets the seconds to wait till the connection is open" do
+    net = Net::HTTP.new("localhost")
+    net.open_timeout = 10
+    net.open_timeout.should.eql?(10)
+  end
+
+  it "returns the newly set value" do
+    net = Net::HTTP.new("localhost")
+    (net.open_timeout = 10).should.eql?(10)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/options_spec.rb b/spec/ruby/library/net-http/http/options_spec.rb
new file mode 100644
index 0000000000..3b90573cfa
--- /dev/null
+++ b/spec/ruby/library/net-http/http/options_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#options" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an options request to the passed path and returns the response" do
+    response = @http.options("/request")
+
+    response.body.should == "Request type: OPTIONS"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.options("/request").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/port_spec.rb b/spec/ruby/library/net-http/http/port_spec.rb
new file mode 100644
index 0000000000..edb689f9ca
--- /dev/null
+++ b/spec/ruby/library/net-http/http/port_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#port" do
+  it "returns the current port number" do
+    net = Net::HTTP.new("localhost", 3333)
+    net.port.should.eql?(3333)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/post2_spec.rb b/spec/ruby/library/net-http/http/post2_spec.rb
new file mode 100644
index 0000000000..abc998709f
--- /dev/null
+++ b/spec/ruby/library/net-http/http/post2_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_post'
+
+describe "Net::HTTP#post2" do
+  it_behaves_like :net_http_request_post, :post2
+end
diff --git a/spec/ruby/library/net-http/http/post_form_spec.rb b/spec/ruby/library/net-http/http/post_form_spec.rb
new file mode 100644
index 0000000000..de64a25bae
--- /dev/null
+++ b/spec/ruby/library/net-http/http/post_form_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.post_form when passed URI" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  it "POSTs the passed form data to the given uri" do
+    uri = URI.parse("http://localhost:#{@port}/request/body")
+    data = { test: :data }
+
+    res = Net::HTTP.post_form(uri, data)
+    res.body.should == "test=data"
+  end
+end
diff --git a/spec/ruby/library/net-http/http/post_spec.rb b/spec/ruby/library/net-http/http/post_spec.rb
new file mode 100644
index 0000000000..f294411197
--- /dev/null
+++ b/spec/ruby/library/net-http/http/post_spec.rb
@@ -0,0 +1,76 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require 'uri'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.post" do
+  before :each do
+    NetHTTPSpecs.start_server
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends post request to the specified URI and returns response" do
+    response = Net::HTTP.post(
+      URI("http://localhost:#{NetHTTPSpecs.port}/request"),
+      '{ "q": "ruby", "max": "50" }',
+      "Content-Type" => "application/json")
+    response.body.should == "Request type: POST"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    response = Net::HTTP.post(URI("http://localhost:#{NetHTTPSpecs.port}/request"), "test=test")
+    response.should.is_a?(Net::HTTPResponse)
+  end
+
+  ruby_version_is ""..."4.0" do
+    it "sends Content-Type: application/x-www-form-urlencoded by default" do
+      response = Net::HTTP.post(URI("http://localhost:#{NetHTTPSpecs.port}/request/header"), "test=test")
+      response.body.should.include?({ "Content-Type" => "application/x-www-form-urlencoded" }.inspect.delete("{}"))
+    end
+  end
+
+  it "does not support HTTP Basic Auth" do
+    response = Net::HTTP.post(
+      URI("http://john:qwerty@localhost:#{NetHTTPSpecs.port}/request/basic_auth"),
+      "test=test")
+    response.body.should == "username: \npassword: "
+  end
+end
+
+describe "Net::HTTP#post" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an post request to the passed path and returns the response" do
+    response = @http.post("/request", "test=test")
+    response.body.should == "Request type: POST"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.post("/request", "test=test").should.is_a?(Net::HTTPResponse)
+  end
+
+  describe "when passed a block" do
+    it "yields fragments of the response body to the passed block" do
+      str = +""
+      @http.post("/request", "test=test") do |res|
+        str << res
+      end
+      str.should == "Request type: POST"
+    end
+
+    it "returns a Net::HTTPResponse" do
+      @http.post("/request", "test=test") {}.should.is_a?(Net::HTTPResponse)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/propfind_spec.rb b/spec/ruby/library/net-http/http/propfind_spec.rb
new file mode 100644
index 0000000000..6a1be0392a
--- /dev/null
+++ b/spec/ruby/library/net-http/http/propfind_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#propfind" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an propfind request to the passed path and returns the response" do
+    response = @http.propfind("/request", "test=test")
+    response.body.should == "Request type: PROPFIND"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.propfind("/request", "test=test").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proppatch_spec.rb b/spec/ruby/library/net-http/http/proppatch_spec.rb
new file mode 100644
index 0000000000..074dfafaef
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proppatch_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#proppatch" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an proppatch request to the passed path and returns the response" do
+    response = @http.proppatch("/request", "test=test")
+    response.body.should == "Request type: PROPPATCH"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.proppatch("/request", "test=test").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proxy_address_spec.rb b/spec/ruby/library/net-http/http/proxy_address_spec.rb
new file mode 100644
index 0000000000..ba040336ad
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proxy_address_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.proxy_address" do
+  describe "when self is no proxy class" do
+    it "returns nil" do
+      Net::HTTP.proxy_address.should == nil
+    end
+  end
+
+  describe "when self is a proxy class" do
+    it "returns the address for self's proxy connection" do
+      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_address.should == "localhost"
+    end
+  end
+end
+
+describe "Net::HTTP#proxy_address" do
+  describe "when self is no proxy class instance" do
+    it "returns nil" do
+      Net::HTTP.new("localhost", 3333).proxy_address.should == nil
+    end
+  end
+
+  describe "when self is a proxy class instance" do
+    it "returns the password for self's proxy connection" do
+      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+      http_with_proxy.new("localhost", 3333).proxy_address.should == "localhost"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proxy_class_spec.rb b/spec/ruby/library/net-http/http/proxy_class_spec.rb
new file mode 100644
index 0000000000..eda027c893
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proxy_class_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.proxy_class?" do
+  it "returns true if self is a class created with Net::HTTP.Proxy" do
+    Net::HTTP.proxy_class?.should == false
+    Net::HTTP.Proxy("localhost").proxy_class?.should == true
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proxy_pass_spec.rb b/spec/ruby/library/net-http/http/proxy_pass_spec.rb
new file mode 100644
index 0000000000..ad02d896c0
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proxy_pass_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.proxy_pass" do
+  describe "when self is no proxy class" do
+    it "returns nil" do
+      Net::HTTP.proxy_pass.should == nil
+    end
+  end
+
+  describe "when self is a proxy class" do
+    it "returns nil if no password was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").proxy_pass.should == nil
+    end
+
+    it "returns the password for self's proxy connection" do
+      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_pass.should == "rocks"
+    end
+  end
+end
+
+describe "Net::HTTP#proxy_pass" do
+  describe "when self is no proxy class instance" do
+    it "returns nil" do
+      Net::HTTP.new("localhost", 3333).proxy_pass.should == nil
+    end
+  end
+
+  describe "when self is a proxy class instance" do
+    it "returns nil if no password was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_pass.should == nil
+    end
+
+    it "returns the password for self's proxy connection" do
+      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+      http_with_proxy.new("localhost", 3333).proxy_pass.should == "rocks"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proxy_port_spec.rb b/spec/ruby/library/net-http/http/proxy_port_spec.rb
new file mode 100644
index 0000000000..21c1e4180e
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proxy_port_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.proxy_port" do
+  describe "when self is no proxy class" do
+    it "returns nil" do
+      Net::HTTP.proxy_port.should == nil
+    end
+  end
+
+  describe "when self is a proxy class" do
+    it "returns 80 if no port was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").proxy_port.should.eql?(80)
+    end
+
+    it "returns the port for self's proxy connection" do
+      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_port.should.eql?(1234)
+    end
+  end
+end
+
+describe "Net::HTTP#proxy_port" do
+  describe "when self is no proxy class instance" do
+    it "returns nil" do
+      Net::HTTP.new("localhost", 3333).proxy_port.should == nil
+    end
+  end
+
+  describe "when self is a proxy class instance" do
+    it "returns 80 if no port was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_port.should.eql?(80)
+    end
+
+    it "returns the port for self's proxy connection" do
+      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+      http_with_proxy.new("localhost", 3333).proxy_port.should.eql?(1234)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/proxy_user_spec.rb b/spec/ruby/library/net-http/http/proxy_user_spec.rb
new file mode 100644
index 0000000000..492ea2e8ee
--- /dev/null
+++ b/spec/ruby/library/net-http/http/proxy_user_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.proxy_user" do
+  describe "when self is no proxy class" do
+    it "returns nil" do
+      Net::HTTP.proxy_user.should == nil
+    end
+  end
+
+  describe "when self is a proxy class" do
+    it "returns nil if no username was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").proxy_user.should == nil
+    end
+
+    it "returns the username for self's proxy connection" do
+      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_user.should == "rspec"
+    end
+  end
+end
+
+describe "Net::HTTP#proxy_user" do
+  describe "when self is no proxy class instance" do
+    it "returns nil" do
+      Net::HTTP.new("localhost", 3333).proxy_user.should == nil
+    end
+  end
+
+  describe "when self is a proxy class instance" do
+    it "returns nil if no username was set for self's proxy connection" do
+      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_user.should == nil
+    end
+
+    it "returns the username for self's proxy connection" do
+      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
+      http_with_proxy.new("localhost", 3333).proxy_user.should == "rspec"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/put2_spec.rb b/spec/ruby/library/net-http/http/put2_spec.rb
new file mode 100644
index 0000000000..7b03a39d0b
--- /dev/null
+++ b/spec/ruby/library/net-http/http/put2_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_put'
+
+describe "Net::HTTP#put2" do
+  it_behaves_like :net_http_request_put, :put2
+end
diff --git a/spec/ruby/library/net-http/http/put_spec.rb b/spec/ruby/library/net-http/http/put_spec.rb
new file mode 100644
index 0000000000..7ef9219f63
--- /dev/null
+++ b/spec/ruby/library/net-http/http/put_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#put" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an put request to the passed path and returns the response" do
+    response = @http.put("/request", "test=test")
+    response.body.should == "Request type: PUT"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.put("/request", "test=test").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/read_timeout_spec.rb b/spec/ruby/library/net-http/http/read_timeout_spec.rb
new file mode 100644
index 0000000000..81e71337bb
--- /dev/null
+++ b/spec/ruby/library/net-http/http/read_timeout_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#read_timeout" do
+  it "returns the seconds to wait until reading one block" do
+    net = Net::HTTP.new("localhost")
+    net.read_timeout.should.eql?(60)
+    net.read_timeout = 10
+    net.read_timeout.should.eql?(10)
+  end
+end
+
+describe "Net::HTTP#read_timeout=" do
+  it "sets the seconds to wait till the connection is open" do
+    net = Net::HTTP.new("localhost")
+    net.read_timeout = 10
+    net.read_timeout.should.eql?(10)
+  end
+
+  it "returns the newly set value" do
+    net = Net::HTTP.new("localhost")
+    (net.read_timeout = 10).should.eql?(10)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/request_get_spec.rb b/spec/ruby/library/net-http/http/request_get_spec.rb
new file mode 100644
index 0000000000..98025a14a1
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_get_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_get'
+
+describe "Net::HTTP#request_get" do
+  it_behaves_like :net_http_request_get, :get2
+end
diff --git a/spec/ruby/library/net-http/http/request_head_spec.rb b/spec/ruby/library/net-http/http/request_head_spec.rb
new file mode 100644
index 0000000000..8f514d4eee
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_head_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_head'
+
+describe "Net::HTTP#request_head" do
+  it_behaves_like :net_http_request_head, :request_head
+end
diff --git a/spec/ruby/library/net-http/http/request_post_spec.rb b/spec/ruby/library/net-http/http/request_post_spec.rb
new file mode 100644
index 0000000000..719bd5a7ee
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_post_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_post'
+
+describe "Net::HTTP#request_post" do
+  it_behaves_like :net_http_request_post, :request_post
+end
diff --git a/spec/ruby/library/net-http/http/request_put_spec.rb b/spec/ruby/library/net-http/http/request_put_spec.rb
new file mode 100644
index 0000000000..9fcf3a98d6
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_put_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/request_put'
+
+describe "Net::HTTP#request_put" do
+  it_behaves_like :net_http_request_put, :request_put
+end
diff --git a/spec/ruby/library/net-http/http/request_spec.rb b/spec/ruby/library/net-http/http/request_spec.rb
new file mode 100644
index 0000000000..e05ee96b55
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_spec.rb
@@ -0,0 +1,109 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#request" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed request_object" do
+    it "makes a HTTP Request based on the passed request_object" do
+      response = @http.request(Net::HTTP::Get.new("/request"), "test=test")
+      response.body.should == "Request type: GET"
+
+      response = @http.request(Net::HTTP::Head.new("/request"), "test=test")
+      response.body.should == nil
+
+      response = @http.request(Net::HTTP::Post.new("/request"), "test=test")
+      response.body.should == "Request type: POST"
+
+      response = @http.request(Net::HTTP::Put.new("/request"), "test=test")
+      response.body.should == "Request type: PUT"
+
+      response = @http.request(Net::HTTP::Proppatch.new("/request"), "test=test")
+      response.body.should == "Request type: PROPPATCH"
+
+      response = @http.request(Net::HTTP::Lock.new("/request"), "test=test")
+      response.body.should == "Request type: LOCK"
+
+      response = @http.request(Net::HTTP::Unlock.new("/request"), "test=test")
+      response.body.should == "Request type: UNLOCK"
+
+      # TODO: Does not work?
+      #response = @http.request(Net::HTTP::Options.new("/request"), "test=test")
+      #response.body.should == nil
+
+      response = @http.request(Net::HTTP::Propfind.new("/request"), "test=test")
+      response.body.should == "Request type: PROPFIND"
+
+      response = @http.request(Net::HTTP::Delete.new("/request"), "test=test")
+      response.body.should == "Request type: DELETE"
+
+      response = @http.request(Net::HTTP::Move.new("/request"), "test=test")
+      response.body.should == "Request type: MOVE"
+
+      response = @http.request(Net::HTTP::Copy.new("/request"), "test=test")
+      response.body.should == "Request type: COPY"
+
+      response = @http.request(Net::HTTP::Mkcol.new("/request"), "test=test")
+      response.body.should == "Request type: MKCOL"
+
+      response = @http.request(Net::HTTP::Trace.new("/request"), "test=test")
+      response.body.should == "Request type: TRACE"
+    end
+  end
+
+  describe "when passed request_object and request_body" do
+    it "sends the passed request_body when making the HTTP Request" do
+      response = @http.request(Net::HTTP::Get.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Head.new("/request/body"), "test=test")
+      response.body.should == nil
+
+      response = @http.request(Net::HTTP::Post.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Put.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Proppatch.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Lock.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Unlock.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      # TODO: Does not work?
+      #response = @http.request(Net::HTTP::Options.new("/request/body"), "test=test")
+      #response.body.should == nil
+
+      response = @http.request(Net::HTTP::Propfind.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Delete.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Move.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Copy.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Mkcol.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+
+      response = @http.request(Net::HTTP::Trace.new("/request/body"), "test=test")
+      response.body.should == "test=test"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/request_types_spec.rb b/spec/ruby/library/net-http/http/request_types_spec.rb
new file mode 100644
index 0000000000..0adc625979
--- /dev/null
+++ b/spec/ruby/library/net-http/http/request_types_spec.rb
@@ -0,0 +1,254 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP::Get" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Get.should < Net::HTTPRequest
+  end
+
+  it "represents the 'GET'-Request-Method" do
+    Net::HTTP::Get::METHOD.should == "GET"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Get::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Get::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Head" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Head.should < Net::HTTPRequest
+  end
+
+  it "represents the 'HEAD'-Request-Method" do
+    Net::HTTP::Head::METHOD.should == "HEAD"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Head::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has no Response Body" do
+    Net::HTTP::Head::RESPONSE_HAS_BODY.should == false
+  end
+end
+
+describe "Net::HTTP::Post" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Post.should < Net::HTTPRequest
+  end
+
+  it "represents the 'POST'-Request-Method" do
+    Net::HTTP::Post::METHOD.should == "POST"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Post::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Post::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Put" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Put.should < Net::HTTPRequest
+  end
+
+  it "represents the 'PUT'-Request-Method" do
+    Net::HTTP::Put::METHOD.should == "PUT"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Put::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Put::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Delete" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Delete.should < Net::HTTPRequest
+  end
+
+  it "represents the 'DELETE'-Request-Method" do
+    Net::HTTP::Delete::METHOD.should == "DELETE"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Delete::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Delete::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Options" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Options.should < Net::HTTPRequest
+  end
+
+  it "represents the 'OPTIONS'-Request-Method" do
+    Net::HTTP::Options::METHOD.should == "OPTIONS"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Options::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has no Response Body" do
+    Net::HTTP::Options::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Trace" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Trace.should < Net::HTTPRequest
+  end
+
+  it "represents the 'TRACE'-Request-Method" do
+    Net::HTTP::Trace::METHOD.should == "TRACE"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Trace::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Trace::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Propfind" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Propfind.should < Net::HTTPRequest
+  end
+
+  it "represents the 'PROPFIND'-Request-Method" do
+    Net::HTTP::Propfind::METHOD.should == "PROPFIND"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Propfind::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Propfind::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Proppatch" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Proppatch.should < Net::HTTPRequest
+  end
+
+  it "represents the 'PROPPATCH'-Request-Method" do
+    Net::HTTP::Proppatch::METHOD.should == "PROPPATCH"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Proppatch::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Proppatch::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Mkcol" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Mkcol.should < Net::HTTPRequest
+  end
+
+  it "represents the 'MKCOL'-Request-Method" do
+    Net::HTTP::Mkcol::METHOD.should == "MKCOL"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Mkcol::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Mkcol::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Copy" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Copy.should < Net::HTTPRequest
+  end
+
+  it "represents the 'COPY'-Request-Method" do
+    Net::HTTP::Copy::METHOD.should == "COPY"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Copy::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Copy::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Move" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Move.should < Net::HTTPRequest
+  end
+
+  it "represents the 'MOVE'-Request-Method" do
+    Net::HTTP::Move::METHOD.should == "MOVE"
+  end
+
+  it "has no Request Body" do
+    Net::HTTP::Move::REQUEST_HAS_BODY.should == false
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Move::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Lock" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Lock.should < Net::HTTPRequest
+  end
+
+  it "represents the 'LOCK'-Request-Method" do
+    Net::HTTP::Lock::METHOD.should == "LOCK"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Lock::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Lock::RESPONSE_HAS_BODY.should == true
+  end
+end
+
+describe "Net::HTTP::Unlock" do
+  it "is a subclass of Net::HTTPRequest" do
+    Net::HTTP::Unlock.should < Net::HTTPRequest
+  end
+
+  it "represents the 'UNLOCK'-Request-Method" do
+    Net::HTTP::Unlock::METHOD.should == "UNLOCK"
+  end
+
+  it "has a Request Body" do
+    Net::HTTP::Unlock::REQUEST_HAS_BODY.should == true
+  end
+
+  it "has a Response Body" do
+    Net::HTTP::Unlock::RESPONSE_HAS_BODY.should == true
+  end
+end
diff --git a/spec/ruby/library/net-http/http/send_request_spec.rb b/spec/ruby/library/net-http/http/send_request_spec.rb
new file mode 100644
index 0000000000..e2dfc505b6
--- /dev/null
+++ b/spec/ruby/library/net-http/http/send_request_spec.rb
@@ -0,0 +1,61 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#send_request" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+
+    # HEAD is special so handled separately
+    @methods = %w[
+      GET POST PUT DELETE
+      OPTIONS
+      PROPFIND PROPPATCH LOCK UNLOCK
+    ]
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  # TODO: Does only work with GET and POST requests
+  describe "when passed type, path" do
+    it "sends a HTTP Request of the passed type to the passed path" do
+      response = @http.send_request("HEAD", "/request")
+      response.body.should == nil
+
+      (@methods - %w[POST PUT]).each do |method|
+        response = @http.send_request(method, "/request")
+        response.body.should == "Request type: #{method}"
+      end
+    end
+  end
+
+  describe "when passed type, path, body" do
+    it "sends a HTTP Request with the passed body" do
+      response = @http.send_request("HEAD", "/request/body", "test=test")
+      response.body.should == nil
+
+      @methods.each do |method|
+        response = @http.send_request(method, "/request/body", "test=test")
+        response.body.should == "test=test"
+      end
+    end
+  end
+
+  describe "when passed type, path, body, headers" do
+    it "sends a HTTP Request with the passed headers" do
+      referer = 'https://www.ruby-lang.org/'.freeze
+
+      response = @http.send_request("HEAD", "/request/header", "test=test", "referer" => referer)
+      response.body.should == nil
+
+      @methods.each do |method|
+        response = @http.send_request(method, "/request/header", "test=test", "referer" => referer)
+        response.body.should.include?({ "Referer" => referer }.inspect.delete("{}"))
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/set_debug_output_spec.rb b/spec/ruby/library/net-http/http/set_debug_output_spec.rb
new file mode 100644
index 0000000000..491ac38b5d
--- /dev/null
+++ b/spec/ruby/library/net-http/http/set_debug_output_spec.rb
@@ -0,0 +1,33 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#set_debug_output when passed io" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sets the passed io as output stream for debugging" do
+    io = StringIO.new
+
+    @http.set_debug_output(io)
+    @http.start
+    io.string.should_not.empty?
+    size = io.string.size
+
+    @http.get("/")
+    io.string.size.should > size
+  end
+
+  it "outputs a warning when the connection has already been started" do
+    @http.start
+    -> { @http.set_debug_output(StringIO.new) }.should complain(/Net::HTTP#set_debug_output called after HTTP started/)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/request_get.rb b/spec/ruby/library/net-http/http/shared/request_get.rb
new file mode 100644
index 0000000000..4f2f152ea4
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/request_get.rb
@@ -0,0 +1,41 @@
+describe :net_http_request_get, shared: true do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed no block" do
+    it "sends a GET request to the passed path and returns the response" do
+      response = @http.send(@method, "/request")
+      response.body.should == "Request type: GET"
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request")
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+
+  describe "when passed a block" do
+    it "sends a GET request to the passed path and returns the response" do
+      response = @http.send(@method, "/request") {}
+      response.body.should == "Request type: GET"
+    end
+
+    it "yields the response to the passed block" do
+      @http.send(@method, "/request") do |response|
+        response.body.should == "Request type: GET"
+      end
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request") {}
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/request_head.rb b/spec/ruby/library/net-http/http/shared/request_head.rb
new file mode 100644
index 0000000000..a5fe787d32
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/request_head.rb
@@ -0,0 +1,41 @@
+describe :net_http_request_head, shared: true do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed no block" do
+    it "sends a head request to the passed path and returns the response" do
+      response = @http.send(@method, "/request")
+      response.body.should == nil
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request")
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+
+  describe "when passed a block" do
+    it "sends a head request to the passed path and returns the response" do
+      response = @http.send(@method, "/request") {}
+      response.body.should == nil
+    end
+
+    it "yields the response to the passed block" do
+      @http.send(@method, "/request") do |response|
+        response.body.should == nil
+      end
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request") {}
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/request_post.rb b/spec/ruby/library/net-http/http/shared/request_post.rb
new file mode 100644
index 0000000000..73cfd577cf
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/request_post.rb
@@ -0,0 +1,41 @@
+describe :net_http_request_post, shared: true do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed no block" do
+    it "sends a post request to the passed path and returns the response" do
+      response = @http.send(@method, "/request", "test=test")
+      response.body.should == "Request type: POST"
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request", "test=test")
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+
+  describe "when passed a block" do
+    it "sends a post request to the passed path and returns the response" do
+      response = @http.send(@method, "/request", "test=test") {}
+      response.body.should == "Request type: POST"
+    end
+
+    it "yields the response to the passed block" do
+      @http.send(@method, "/request", "test=test") do |response|
+        response.body.should == "Request type: POST"
+      end
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request", "test=test") {}
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/request_put.rb b/spec/ruby/library/net-http/http/shared/request_put.rb
new file mode 100644
index 0000000000..3b64d7e055
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/request_put.rb
@@ -0,0 +1,41 @@
+describe :net_http_request_put, shared: true do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when passed no block" do
+    it "sends a put request to the passed path and returns the response" do
+      response = @http.send(@method, "/request", "test=test")
+      response.body.should == "Request type: PUT"
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request", "test=test")
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+
+  describe "when passed a block" do
+    it "sends a put request to the passed path and returns the response" do
+      response = @http.send(@method, "/request", "test=test") {}
+      response.body.should == "Request type: PUT"
+    end
+
+    it "yields the response to the passed block" do
+      @http.send(@method, "/request", "test=test") do |response|
+        response.body.should == "Request type: PUT"
+      end
+    end
+
+    it "returns a Net::HTTPResponse object" do
+      response = @http.send(@method, "/request", "test=test") {}
+      response.should.is_a?(Net::HTTPResponse)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/started.rb b/spec/ruby/library/net-http/http/shared/started.rb
new file mode 100644
index 0000000000..0ab18a4e83
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/started.rb
@@ -0,0 +1,26 @@
+describe :net_http_started_p, shared: true do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "returns true when self has been started" do
+    @http.start
+    @http.send(@method).should == true
+  end
+
+  it "returns false when self has not been started yet" do
+    @http.send(@method).should == false
+  end
+
+  it "returns false when self has been stopped again" do
+    @http.start
+    @http.finish
+    @http.send(@method).should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/version_1_1.rb b/spec/ruby/library/net-http/http/shared/version_1_1.rb
new file mode 100644
index 0000000000..84e7264eab
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/version_1_1.rb
@@ -0,0 +1,6 @@
+describe :net_http_version_1_1_p, shared: true do
+  it "returns the state of net/http 1.1 features" do
+    Net::HTTP.version_1_2
+    Net::HTTP.send(@method).should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/http/shared/version_1_2.rb b/spec/ruby/library/net-http/http/shared/version_1_2.rb
new file mode 100644
index 0000000000..dcf5419704
--- /dev/null
+++ b/spec/ruby/library/net-http/http/shared/version_1_2.rb
@@ -0,0 +1,6 @@
+describe :net_http_version_1_2_p, shared: true do
+  it "returns the state of net/http 1.2 features" do
+    Net::HTTP.version_1_2
+    Net::HTTP.send(@method).should == true
+  end
+end
diff --git a/spec/ruby/library/net-http/http/socket_type_spec.rb b/spec/ruby/library/net-http/http/socket_type_spec.rb
new file mode 100644
index 0000000000..f6826777b0
--- /dev/null
+++ b/spec/ruby/library/net-http/http/socket_type_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP.socket_type" do
+  it "returns BufferedIO" do
+    Net::HTTP.socket_type.should == Net::BufferedIO
+  end
+end
diff --git a/spec/ruby/library/net-http/http/start_spec.rb b/spec/ruby/library/net-http/http/start_spec.rb
new file mode 100644
index 0000000000..1aebc16f4d
--- /dev/null
+++ b/spec/ruby/library/net-http/http/start_spec.rb
@@ -0,0 +1,111 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP.start" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @port = NetHTTPSpecs.port
+  end
+
+  after :each do
+    NetHTTPSpecs.stop_server
+  end
+
+  describe "when not passed a block" do
+    before :each do
+      @http = Net::HTTP.start("localhost", @port)
+    end
+
+    after :each do
+      @http.finish if @http.started?
+    end
+
+    it "returns a new Net::HTTP object for the passed address and port" do
+      @http.should.is_a?(Net::HTTP)
+      @http.address.should == "localhost"
+      @http.port.should == @port
+    end
+
+    it "opens the tcp connection" do
+      @http.started?.should == true
+    end
+  end
+
+  describe "when passed a block" do
+    it "returns the blocks return value" do
+      Net::HTTP.start("localhost", @port) { :test }.should == :test
+    end
+
+    it "yields the new Net::HTTP object to the block" do
+      yielded = false
+      Net::HTTP.start("localhost", @port) do |net|
+        yielded = true
+        net.should.is_a?(Net::HTTP)
+      end
+      yielded.should == true
+    end
+
+    it "opens the tcp connection before yielding" do
+      Net::HTTP.start("localhost", @port) { |http| http.started?.should == true }
+    end
+
+    it "closes the tcp connection after yielding" do
+      net = nil
+      Net::HTTP.start("localhost", @port) { |x| net = x }
+      net.started?.should == false
+    end
+  end
+end
+
+describe "Net::HTTP#start" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "returns self" do
+    @http.start.should.equal?(@http)
+  end
+
+  it "opens the tcp connection" do
+    @http.start
+    @http.started?.should == true
+  end
+
+  describe "when self has already been started" do
+    it "raises an IOError" do
+      @http.start
+      -> { @http.start }.should.raise(IOError)
+    end
+  end
+
+  describe "when passed a block" do
+    it "returns the blocks return value" do
+      @http.start { :test }.should == :test
+    end
+
+    it "yields the new Net::HTTP object to the block" do
+      yielded = false
+      @http.start do |http|
+        yielded = true
+        http.should.equal?(@http)
+      end
+      yielded.should == true
+    end
+
+    it "opens the tcp connection before yielding" do
+      @http.start { |http| http.started?.should == true }
+    end
+
+    it "closes the tcp connection after yielding" do
+      @http.start { }
+      @http.started?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/http/started_spec.rb b/spec/ruby/library/net-http/http/started_spec.rb
new file mode 100644
index 0000000000..cbb82ceefa
--- /dev/null
+++ b/spec/ruby/library/net-http/http/started_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+require_relative 'shared/started'
+
+describe "Net::HTTP#started?" do
+  it_behaves_like :net_http_started_p, :started?
+end
diff --git a/spec/ruby/library/net-http/http/trace_spec.rb b/spec/ruby/library/net-http/http/trace_spec.rb
new file mode 100644
index 0000000000..e0ff741b04
--- /dev/null
+++ b/spec/ruby/library/net-http/http/trace_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#trace" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends a TRACE request to the passed path and returns the response" do
+    response = @http.trace("/request")
+    response.body.should == "Request type: TRACE"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.trace("/request").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/unlock_spec.rb b/spec/ruby/library/net-http/http/unlock_spec.rb
new file mode 100644
index 0000000000..cbfc803f09
--- /dev/null
+++ b/spec/ruby/library/net-http/http/unlock_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/http_server'
+
+describe "Net::HTTP#unlock" do
+  before :each do
+    NetHTTPSpecs.start_server
+    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
+  end
+
+  after :each do
+    @http.finish if @http.started?
+    NetHTTPSpecs.stop_server
+  end
+
+  it "sends an UNLOCK request to the passed path and returns the response" do
+    response = @http.unlock("/request", "test=test")
+    response.body.should == "Request type: UNLOCK"
+  end
+
+  it "returns a Net::HTTPResponse" do
+    @http.unlock("/request", "test=test").should.is_a?(Net::HTTPResponse)
+  end
+end
diff --git a/spec/ruby/library/net-http/http/use_ssl_spec.rb b/spec/ruby/library/net-http/http/use_ssl_spec.rb
new file mode 100644
index 0000000000..b283655359
--- /dev/null
+++ b/spec/ruby/library/net-http/http/use_ssl_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTP#use_ssl?" do
+  it "returns false" do
+    http = Net::HTTP.new("localhost")
+    http.use_ssl?.should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/http/version_1_1_spec.rb b/spec/ruby/library/net-http/http/version_1_1_spec.rb
new file mode 100644
index 0000000000..34a4ac8a6b
--- /dev/null
+++ b/spec/ruby/library/net-http/http/version_1_1_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/version_1_1'
+
+describe "Net::HTTP.version_1_1?" do
+  it_behaves_like :net_http_version_1_1_p, :version_1_1?
+end
diff --git a/spec/ruby/library/net-http/http/version_1_2_spec.rb b/spec/ruby/library/net-http/http/version_1_2_spec.rb
new file mode 100644
index 0000000000..4918597234
--- /dev/null
+++ b/spec/ruby/library/net-http/http/version_1_2_spec.rb
@@ -0,0 +1,20 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/version_1_2'
+
+describe "Net::HTTP.version_1_2" do
+  it "turns on net/http 1.2 features" do
+    Net::HTTP.version_1_2
+
+    Net::HTTP.version_1_2?.should == true
+    Net::HTTP.version_1_1?.should == false
+  end
+
+  it "returns true" do
+    Net::HTTP.version_1_2.should == true
+  end
+end
+
+describe "Net::HTTP.version_1_2?" do
+  it_behaves_like :net_http_version_1_2_p, :version_1_2?
+end
diff --git a/spec/ruby/library/net/http/httpexceptions/fixtures/classes.rb b/spec/ruby/library/net-http/httpexceptions/fixtures/classes.rb
index abe8855eff..abe8855eff 100644
--- a/spec/ruby/library/net/http/httpexceptions/fixtures/classes.rb
+++ b/spec/ruby/library/net-http/httpexceptions/fixtures/classes.rb
diff --git a/spec/ruby/library/net-http/httpexceptions/initialize_spec.rb b/spec/ruby/library/net-http/httpexceptions/initialize_spec.rb
new file mode 100644
index 0000000000..5316cca69d
--- /dev/null
+++ b/spec/ruby/library/net-http/httpexceptions/initialize_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPExceptions#initialize when passed message, response" do
+  before :each do
+    @exception = NetHTTPExceptionsSpecs::Simple.new("error message", "a http response")
+  end
+
+  it "calls super with the passed message" do
+    @exception.message.should == "error message"
+  end
+
+  it "sets self's response to the passed response" do
+    @exception.response.should == "a http response"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpexceptions/response_spec.rb b/spec/ruby/library/net-http/httpexceptions/response_spec.rb
new file mode 100644
index 0000000000..d718b1ae21
--- /dev/null
+++ b/spec/ruby/library/net-http/httpexceptions/response_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPExceptions#response" do
+  it "returns self's response" do
+    exception = NetHTTPExceptionsSpecs::Simple.new("error message", "a http response")
+    exception.response.should == "a http response"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/body_exist_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/body_exist_spec.rb
new file mode 100644
index 0000000000..96a761929e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/body_exist_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#body_exist?" do
+  it "returns true when the response is expected to have a body" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.body_exist?.should == true
+
+    request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
+    request.body_exist?.should == false
+  end
+
+  describe "when $VERBOSE is true" do
+    it "emits a warning" do
+      request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
+      -> {
+        request.body_exist?
+      }.should complain(/body_exist\? is obsolete/, verbose: true)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/body_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/body_spec.rb
new file mode 100644
index 0000000000..63cda994e5
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/body_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+
+describe "Net::HTTPGenericRequest#body" do
+  it "returns self's request body" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.body.should == nil
+
+    request.body = "Some Content"
+    request.body.should == "Some Content"
+  end
+end
+
+describe "Net::HTTPGenericRequest#body=" do
+  before :each do
+    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+  end
+
+  it "sets self's body content to the passed String" do
+    @request.body = "Some Content"
+    @request.body.should == "Some Content"
+  end
+
+  it "sets self's body stream to nil" do
+    @request.body_stream = StringIO.new("")
+    @request.body = "Some Content"
+    @request.body_stream.should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/body_stream_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/body_stream_spec.rb
new file mode 100644
index 0000000000..3237dbb861
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/body_stream_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+
+describe "Net::HTTPGenericRequest#body_stream" do
+  it "returns self's body stream Object" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.body_stream.should == nil
+
+    stream = StringIO.new("test")
+    request.body_stream = stream
+    request.body_stream.should.equal?(stream)
+  end
+end
+
+describe "Net::HTTPGenericRequest#body_stream=" do
+  before :each do
+    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    @stream = StringIO.new("test")
+  end
+
+  it "sets self's body stream to the passed Object" do
+    @request.body_stream = @stream
+    @request.body_stream.should.equal?(@stream)
+  end
+
+  it "sets self's body to nil" do
+    @request.body = "Some Content"
+    @request.body_stream = @stream
+    @request.body.should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/exec_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/exec_spec.rb
new file mode 100644
index 0000000000..0ccf80e3b6
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/exec_spec.rb
@@ -0,0 +1,135 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+
+describe "Net::HTTPGenericRequest#exec when passed socket, version, path" do
+  before :each do
+    @socket = StringIO.new(+"")
+    @buffered_socket = Net::BufferedIO.new(@socket)
+  end
+
+  it "executes the request over the socket to the path using the HTTP version" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+
+    request.exec(@buffered_socket, "1.1", "/some/path")
+    str = @socket.string
+
+    str.should =~ %r[POST /some/path HTTP/1.1\r\n]
+    str.should =~ %r[Accept: \*/\*\r\n]
+    str[-4..-1].should == "\r\n\r\n"
+
+    request = Net::HTTPGenericRequest.new("GET", true, true, "/some/path",
+                                          "Content-Type" => "text/html")
+
+    request.exec(@buffered_socket, "1.0", "/some/other/path")
+    str = @socket.string
+
+    str.should =~ %r[GET /some/other/path HTTP/1.0\r\n]
+    str.should =~ %r[Accept: \*/\*\r\n]
+    str.should =~ %r[Content-Type: text/html\r\n]
+    str[-4..-1].should == "\r\n\r\n"
+  end
+
+  describe "when a request body is set" do
+    ruby_version_is ""..."4.0" do
+      it "sets the 'Content-Type' header to 'application/x-www-form-urlencoded' unless the 'Content-Type' header is supplied" do
+        request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+        request.body = "Some Content"
+
+        request.exec(@buffered_socket, "1.1", "/some/other/path")
+        str = @socket.string
+
+        str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
+        str.should =~ %r[Accept: \*/\*\r\n]
+        str.should =~ %r[Content-Type: application/x-www-form-urlencoded\r\n]
+        str.should =~ %r[Content-Length: 12\r\n]
+        str[-16..-1].should == "\r\n\r\nSome Content"
+      end
+    end
+
+    it "correctly sets the 'Content-Length' header and includes the body" do
+      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
+                                            "Content-Type" => "text/html")
+      request.body = "Some Content"
+
+      request.exec(@buffered_socket, "1.1", "/some/other/path")
+      str = @socket.string
+
+      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
+      str.should =~ %r[Accept: \*/\*\r\n]
+      str.should =~ %r[Content-Type: text/html\r\n]
+      str.should =~ %r[Content-Length: 12\r\n]
+      str[-16..-1].should == "\r\n\r\nSome Content"
+    end
+  end
+
+  describe "when a body stream is set" do
+    ruby_version_is ""..."4.0" do
+      it "sets the 'Content-Type' header to 'application/x-www-form-urlencoded' unless the 'Content-Type' header is supplied" do
+        request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
+                                              "Content-Length" => "10")
+        request.body_stream = StringIO.new("a" * 20)
+
+        request.exec(@buffered_socket, "1.1", "/some/other/path")
+        str = @socket.string
+
+        str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
+        str.should =~ %r[Accept: \*/\*\r\n]
+        str.should =~ %r[Content-Type: application/x-www-form-urlencoded\r\n]
+        str.should =~ %r[Content-Length: 10\r\n]
+        str[-24..-1].should == "\r\n\r\naaaaaaaaaaaaaaaaaaaa"
+      end
+    end
+
+    it "sends the whole stream, regardless of the 'Content-Length' header" do
+      request = Net::HTTPGenericRequest.new("POST", true, true,"/some/path",
+                                            "Content-Type" => "text/html",
+                                            "Content-Length" => "10")
+      request.body_stream = StringIO.new("a" * 20)
+
+      request.exec(@buffered_socket, "1.1", "/some/other/path")
+      str = @socket.string
+
+      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
+      str.should =~ %r[Accept: \*/\*\r\n]
+      str.should =~ %r[Content-Type: text/html\r\n]
+      str.should =~ %r[Content-Length: 10\r\n]
+      str[-24..-1].should == "\r\n\r\naaaaaaaaaaaaaaaaaaaa"
+    end
+
+    it "sends the request in chunks when 'Transfer-Encoding' is set to 'chunked'" do
+      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
+                                            "Content-Type" => "text/html",
+                                            "Transfer-Encoding" => "chunked")
+      datasize = 1024 * 10
+      request.body_stream = StringIO.new("a" * datasize)
+
+      request.exec(@buffered_socket, "1.1", "/some/other/path")
+      str = @socket.string
+
+      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
+      str.should =~ %r[Accept: \*/\*\r\n]
+      str.should =~ %r[Content-Type: text/html\r\n]
+      str.should =~ %r[Transfer-Encoding: chunked\r\n]
+      str =~ %r[\r\n\r\n]
+      str = $'
+      while datasize > 0
+        chunk_size_line, str = str.split(/\r\n/, 2)
+        chunk_size = chunk_size_line[/\A[0-9A-Fa-f]+/].to_i(16)
+        str.slice!(0, chunk_size).should == 'a' * chunk_size
+        datasize -= chunk_size
+        str.slice!(0, 2).should == "\r\n"
+      end
+      datasize.should == 0
+      str.should == %"0\r\n\r\n"
+    end
+
+    it "raises an ArgumentError when the 'Content-Length' is not set or 'Transfer-Encoding' is not set to 'chunked'" do
+      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
+                                            "Content-Type" => "text/html")
+      request.body_stream = StringIO.new("Some Content")
+
+      -> { request.exec(@buffered_socket, "1.1", "/some/other/path") }.should.raise(ArgumentError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/inspect_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/inspect_spec.rb
new file mode 100644
index 0000000000..d03b6e6953
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/inspect_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#inspect" do
+  it "returns a String representation of self" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.inspect.should == "#<Net::HTTPGenericRequest POST>"
+
+    request = Net::HTTPGenericRequest.new("GET", false, true, "/some/path")
+    request.inspect.should == "#<Net::HTTPGenericRequest GET>"
+
+    request = Net::HTTPGenericRequest.new("BLA", true, true, "/some/path")
+    request.inspect.should == "#<Net::HTTPGenericRequest BLA>"
+
+    # Subclasses
+    request = Net::HTTP::Get.new("/some/path")
+    request.inspect.should == "#<Net::HTTP::Get GET>"
+
+    request = Net::HTTP::Post.new("/some/path")
+    request.inspect.should == "#<Net::HTTP::Post POST>"
+
+    request = Net::HTTP::Trace.new("/some/path")
+    request.inspect.should == "#<Net::HTTP::Trace TRACE>"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/method_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/method_spec.rb
new file mode 100644
index 0000000000..794bd328cd
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/method_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#method" do
+  it "returns self's request method" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.method.should == "POST"
+
+    request = Net::HTTPGenericRequest.new("GET", false, true, "/some/path")
+    request.method.should == "GET"
+
+    request = Net::HTTPGenericRequest.new("BLA", true, true, "/some/path")
+    request.method.should == "BLA"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/path_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/path_spec.rb
new file mode 100644
index 0000000000..a9fac3f67e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/path_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#path" do
+  it "returns self's request path" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.path.should == "/some/path"
+
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/other/path")
+    request.path.should == "/some/other/path"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/request_body_permitted_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/request_body_permitted_spec.rb
new file mode 100644
index 0000000000..ba836e8130
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/request_body_permitted_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#request_body_permitted?" do
+  it "returns true when the request is expected to have a body" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.request_body_permitted?.should == true
+
+    request = Net::HTTPGenericRequest.new("POST", false, true, "/some/path")
+    request.request_body_permitted?.should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/response_body_permitted_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/response_body_permitted_spec.rb
new file mode 100644
index 0000000000..067500f60d
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/response_body_permitted_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#response_body_permitted?" do
+  it "returns true when the response is expected to have a body" do
+    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+    request.response_body_permitted?.should == true
+
+    request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
+    request.response_body_permitted?.should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/httpgenericrequest/set_body_internal_spec.rb b/spec/ruby/library/net-http/httpgenericrequest/set_body_internal_spec.rb
new file mode 100644
index 0000000000..f241d8d698
--- /dev/null
+++ b/spec/ruby/library/net-http/httpgenericrequest/set_body_internal_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPGenericRequest#set_body_internal when passed string" do
+  before :each do
+    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
+  end
+
+  it "sets self's body to the passed string" do
+    @request.set_body_internal("Some Content")
+    @request.body.should == "Some Content"
+  end
+
+  it "raises an ArgumentError when the body or body_stream of self have already been set" do
+    @request.body = "Some Content"
+    -> { @request.set_body_internal("Some other Content") }.should.raise(ArgumentError)
+
+    @request.body_stream = "Some Content"
+    -> { @request.set_body_internal("Some other Content") }.should.raise(ArgumentError)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/add_field_spec.rb b/spec/ruby/library/net-http/httpheader/add_field_spec.rb
new file mode 100644
index 0000000000..8cd3d33517
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/add_field_spec.rb
@@ -0,0 +1,31 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#add_field when passed key, value" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "adds the passed value to the header entry with the passed key" do
+    @headers.add_field("My-Header", "a")
+    @headers.get_fields("My-Header").should == ["a"]
+
+    @headers.add_field("My-Header", "b")
+    @headers.get_fields("My-Header").should == ["a", "b"]
+
+    @headers.add_field("My-Header", "c")
+    @headers.get_fields("My-Header").should == ["a", "b", "c"]
+  end
+
+  it "is case-insensitive" do
+    @headers.add_field("My-Header", "a")
+    @headers.get_fields("My-Header").should == ["a"]
+
+    @headers.add_field("my-header", "b")
+    @headers.get_fields("My-Header").should == ["a", "b"]
+
+    @headers.add_field("MY-HEADER", "c")
+    @headers.get_fields("My-Header").should == ["a", "b", "c"]
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/basic_auth_spec.rb b/spec/ruby/library/net-http/httpheader/basic_auth_spec.rb
new file mode 100644
index 0000000000..db7ca84d13
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/basic_auth_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#basic_auth when passed account, password" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "sets the 'Authorization' Header entry for basic authorization" do
+    @headers.basic_auth("rubyspec", "rocks")
+    @headers["Authorization"].should == "Basic cnVieXNwZWM6cm9ja3M="
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/canonical_each_spec.rb b/spec/ruby/library/net-http/httpheader/canonical_each_spec.rb
new file mode 100644
index 0000000000..64a5cae89e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/canonical_each_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_capitalized'
+
+describe "Net::HTTPHeader#canonical_each" do
+  it_behaves_like :net_httpheader_each_capitalized, :canonical_each
+end
diff --git a/spec/ruby/library/net-http/httpheader/chunked_spec.rb b/spec/ruby/library/net-http/httpheader/chunked_spec.rb
new file mode 100644
index 0000000000..4da218ae25
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/chunked_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#chunked?" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns true if the 'Transfer-Encoding' header entry is set to chunked" do
+    @headers.chunked?.should == false
+
+    @headers["Transfer-Encoding"] = "bla"
+    @headers.chunked?.should == false
+
+    @headers["Transfer-Encoding"] = "blachunkedbla"
+    @headers.chunked?.should == false
+
+    @headers["Transfer-Encoding"] = "chunked"
+    @headers.chunked?.should == true
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/content_length_spec.rb b/spec/ruby/library/net-http/httpheader/content_length_spec.rb
new file mode 100644
index 0000000000..c66d5673c1
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/content_length_spec.rb
@@ -0,0 +1,54 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#content_length" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns nil if no 'Content-Length' header entry is set" do
+    @headers.content_length.should == nil
+  end
+
+  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Length' header entry has an invalid format" do
+    @headers["Content-Length"] = "invalid"
+    -> { @headers.content_length }.should.raise(Net::HTTPHeaderSyntaxError)
+  end
+
+  it "returns the value of the 'Content-Length' header entry as an Integer" do
+    @headers["Content-Length"] = "123"
+    @headers.content_length.should.eql?(123)
+
+    @headers["Content-Length"] = "123valid"
+    @headers.content_length.should.eql?(123)
+
+    @headers["Content-Length"] = "valid123"
+    @headers.content_length.should.eql?(123)
+  end
+end
+
+describe "Net::HTTPHeader#content_length=" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "removes the 'Content-Length' entry if passed false or nil" do
+    @headers["Content-Length"] = "123"
+    @headers.content_length = nil
+    @headers["Content-Length"].should == nil
+  end
+
+  it "sets the 'Content-Length' entry to the passed value" do
+    @headers.content_length = "123"
+    @headers["Content-Length"].should == "123"
+
+    @headers.content_length = "123valid"
+    @headers["Content-Length"].should == "123"
+  end
+
+  it "sets the 'Content-Length' entry to 0 if the passed value is not valid" do
+    @headers.content_length = "invalid123"
+    @headers["Content-Length"].should == "0"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/content_range_spec.rb b/spec/ruby/library/net-http/httpheader/content_range_spec.rb
new file mode 100644
index 0000000000..3635fb3f1b
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/content_range_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#content_range" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns a Range object that represents the 'Content-Range' header entry" do
+    @headers["Content-Range"] = "bytes 0-499/1234"
+    @headers.content_range.should == (0..499)
+
+    @headers["Content-Range"] = "bytes 500-1233/1234"
+    @headers.content_range.should == (500..1233)
+  end
+
+  it "returns nil when there is no 'Content-Range' header entry" do
+    @headers.content_range.should == nil
+  end
+
+  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Range' has an invalid format" do
+    @headers["Content-Range"] = "invalid"
+    -> { @headers.content_range }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Content-Range"] = "bytes 123-abc"
+    -> { @headers.content_range }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Content-Range"] = "bytes abc-123"
+    -> { @headers.content_range }.should.raise(Net::HTTPHeaderSyntaxError)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/content_type_spec.rb b/spec/ruby/library/net-http/httpheader/content_type_spec.rb
new file mode 100644
index 0000000000..c9c936ba0f
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/content_type_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_content_type'
+
+describe "Net::HTTPHeader#content_type" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the content type string, as per 'Content-Type' header entry" do
+    @headers["Content-Type"] = "text/html"
+    @headers.content_type.should == "text/html"
+
+    @headers["Content-Type"] = "text/html;charset=utf-8"
+    @headers.content_type.should == "text/html"
+  end
+
+  it "returns nil if the 'Content-Type' header entry does not exist" do
+    @headers.content_type.should == nil
+  end
+end
+
+describe "Net::HTTPHeader#content_type=" do
+  it_behaves_like :net_httpheader_set_content_type, :content_type=
+end
diff --git a/spec/ruby/library/net-http/httpheader/delete_spec.rb b/spec/ruby/library/net-http/httpheader/delete_spec.rb
new file mode 100644
index 0000000000..09bae65a13
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/delete_spec.rb
@@ -0,0 +1,30 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#delete when passed key" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "removes the header entry with the passed key" do
+    @headers["My-Header"] = "test"
+    @headers.delete("My-Header")
+
+    @headers["My-Header"].should == nil
+    @headers.size.should.eql?(0)
+  end
+
+  it "returns the removed values" do
+    @headers["My-Header"] = "test"
+    @headers.delete("My-Header").should == ["test"]
+  end
+
+  it "is case-insensitive" do
+    @headers["My-Header"] = "test"
+    @headers.delete("my-header")
+
+    @headers["My-Header"].should == nil
+    @headers.size.should.eql?(0)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_capitalized_name_spec.rb b/spec/ruby/library/net-http/httpheader/each_capitalized_name_spec.rb
new file mode 100644
index 0000000000..54874c0535
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_capitalized_name_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#each_capitalized_name" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+    @headers["My-Header"] = "test"
+    @headers.add_field("My-Other-Header", "a")
+    @headers.add_field("My-Other-Header", "b")
+  end
+
+  describe "when passed a block" do
+    it "yields each header key to the passed block (keys capitalized)" do
+      res = []
+      @headers.each_capitalized_name do |key|
+        res << key
+      end
+      res.sort.should == ["My-Header", "My-Other-Header"]
+    end
+  end
+
+  describe "when passed no block" do
+    it "returns an Enumerator" do
+      enumerator = @headers.each_capitalized_name
+      enumerator.should.instance_of?(Enumerator)
+
+      res = []
+      enumerator.each do |key|
+        res << key
+      end
+      res.sort.should == ["My-Header", "My-Other-Header"]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_capitalized_spec.rb b/spec/ruby/library/net-http/httpheader/each_capitalized_spec.rb
new file mode 100644
index 0000000000..1e853995ea
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_capitalized_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_capitalized'
+
+describe "Net::HTTPHeader#each_capitalized" do
+  it_behaves_like :net_httpheader_each_capitalized, :each_capitalized
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_header_spec.rb b/spec/ruby/library/net-http/httpheader/each_header_spec.rb
new file mode 100644
index 0000000000..869feebacf
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_header_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_header'
+
+describe "Net::HTTPHeader#each_header" do
+  it_behaves_like :net_httpheader_each_header, :each_header
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_key_spec.rb b/spec/ruby/library/net-http/httpheader/each_key_spec.rb
new file mode 100644
index 0000000000..1ad145629f
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_key_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_name'
+
+describe "Net::HTTPHeader#each_key" do
+  it_behaves_like :net_httpheader_each_name, :each_key
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_name_spec.rb b/spec/ruby/library/net-http/httpheader/each_name_spec.rb
new file mode 100644
index 0000000000..f819bd989d
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_name_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_name'
+
+describe "Net::HTTPHeader#each_name" do
+  it_behaves_like :net_httpheader_each_name, :each_name
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_spec.rb b/spec/ruby/library/net-http/httpheader/each_spec.rb
new file mode 100644
index 0000000000..ff37249d0a
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/each_header'
+
+describe "Net::HTTPHeader#each" do
+  it_behaves_like :net_httpheader_each_header, :each
+end
diff --git a/spec/ruby/library/net-http/httpheader/each_value_spec.rb b/spec/ruby/library/net-http/httpheader/each_value_spec.rb
new file mode 100644
index 0000000000..55ba4c1ef8
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/each_value_spec.rb
@@ -0,0 +1,35 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#each_value" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+    @headers["My-Header"] = "test"
+    @headers.add_field("My-Other-Header", "a")
+    @headers.add_field("My-Other-Header", "b")
+  end
+
+  describe "when passed a block" do
+    it "yields each header entry's joined values" do
+      res = []
+      @headers.each_value do |value|
+        res << value
+      end
+      res.sort.should == ["a, b", "test"]
+    end
+  end
+
+  describe "when passed no block" do
+    it "returns an Enumerator" do
+      enumerator = @headers.each_value
+      enumerator.should.instance_of?(Enumerator)
+
+      res = []
+      enumerator.each do |key|
+        res << key
+      end
+      res.sort.should == ["a, b", "test"]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/element_reference_spec.rb b/spec/ruby/library/net-http/httpheader/element_reference_spec.rb
new file mode 100644
index 0000000000..f12f8494db
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/element_reference_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#[] when passed key" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the value of the header entry with the passed key" do
+    @headers["My-Header"] = "test"
+    @headers["My-Header"].should == "test"
+    @headers["My-Other-Header"] = "another test"
+    @headers["My-Other-Header"].should == "another test"
+  end
+
+  it "is case-insensitive" do
+    @headers["My-Header"] = "test"
+
+    @headers['My-Header'].should == "test"
+    @headers['my-Header'].should == "test"
+    @headers['My-header'].should == "test"
+    @headers['my-header'].should == "test"
+    @headers['MY-HEADER'].should == "test"
+  end
+
+  it "returns multi-element values joined together" do
+    @headers["My-Header"] = "test"
+    @headers.add_field("My-Header", "another test")
+    @headers.add_field("My-Header", "and one more")
+
+    @headers["My-Header"].should == "test, another test, and one more"
+  end
+
+  it "returns nil for non-existing entries" do
+    @headers["My-Header"].should == nil
+    @headers["My-Other-Header"].should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/element_set_spec.rb b/spec/ruby/library/net-http/httpheader/element_set_spec.rb
new file mode 100644
index 0000000000..633fe18b2e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/element_set_spec.rb
@@ -0,0 +1,41 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#[]= when passed key, value" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "sets the header entry with the passed key to the passed value" do
+    @headers["My-Header"] = "test"
+    @headers["My-Header"].should == "test"
+
+    @headers["My-Header"] = "overwritten"
+    @headers["My-Header"].should == "overwritten"
+
+    @headers["My-Other-Header"] = "another test"
+    @headers["My-Other-Header"].should == "another test"
+  end
+
+  it "is case-insensitive" do
+    @headers['My-Header'] = "test"
+    @headers['my-Header'] = "another test"
+    @headers['My-header'] = "and one more test"
+    @headers['my-header'] = "and another one"
+    @headers['MY-HEADER'] = "last one"
+
+    @headers["My-Header"].should == "last one"
+    @headers.size.should.eql?(1)
+  end
+
+  it "removes the header entry with the passed key when the value is false or nil" do
+    @headers['My-Header'] = "test"
+    @headers['My-Header'] = nil
+    @headers['My-Header'].should == nil
+
+    @headers['My-Header'] = "test"
+    @headers['My-Header'] = false
+    @headers['My-Header'].should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/fetch_spec.rb b/spec/ruby/library/net-http/httpheader/fetch_spec.rb
new file mode 100644
index 0000000000..d1c273dada
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/fetch_spec.rb
@@ -0,0 +1,68 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#fetch" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  describe "when passed key" do
+    it "returns the header entry for the passed key" do
+      @headers["My-Header"] = "test"
+      @headers.fetch("My-Header").should == "test"
+
+      @headers.add_field("My-Other-Header", "a")
+      @headers.add_field("My-Other-Header", "b")
+      @headers.add_field("My-Other-Header", "c")
+      @headers.fetch("My-Other-Header").should == "a, b, c"
+    end
+
+    it "is case-insensitive" do
+      @headers["My-Header"] = "test"
+      @headers.fetch("my-header").should == "test"
+      @headers.fetch("MY-HEADER").should == "test"
+    end
+
+    it "returns nil when there is no entry for the passed key" do
+      -> { @headers.fetch("my-header") }.should.raise(IndexError)
+    end
+  end
+
+  describe "when passed key, default" do
+    it "returns the header entry for the passed key" do
+      @headers["My-Header"] = "test"
+      @headers.fetch("My-Header", "bla").should == "test"
+
+      @headers.add_field("My-Other-Header", "a")
+      @headers.add_field("My-Other-Header", "b")
+      @headers.add_field("My-Other-Header", "c")
+      @headers.fetch("My-Other-Header", "bla").should == "a, b, c"
+    end
+
+    # TODO: This raises a NoMethodError: undefined method `join' for "bla":String
+    it "returns the default value when there is no entry for the passed key" do
+      @headers.fetch("My-Header", "bla").should == "bla"
+    end
+  end
+
+  describe "when passed key and block" do
+    it "returns the header entry for the passed key" do
+      @headers["My-Header"] = "test"
+      @headers.fetch("My-Header") {}.should == "test"
+
+      @headers.add_field("My-Other-Header", "a")
+      @headers.add_field("My-Other-Header", "b")
+      @headers.add_field("My-Other-Header", "c")
+      -> {
+        @result = @headers.fetch("My-Other-Header", "bla") {}
+      }.should complain(/block supersedes default value argument/)
+      @result.should == "a, b, c"
+    end
+
+    # TODO: This raises a NoMethodError: undefined method `join' for "redaeh-ym":String
+    it "yieldsand returns the block's return value when there is no entry for the passed key" do
+      @headers.fetch("My-Header") { |key| key.reverse }.should == "redaeh-ym"
+    end
+  end
+end
diff --git a/spec/ruby/library/net/http/httpheader/fixtures/classes.rb b/spec/ruby/library/net-http/httpheader/fixtures/classes.rb
index b5ec6abd75..b5ec6abd75 100644
--- a/spec/ruby/library/net/http/httpheader/fixtures/classes.rb
+++ b/spec/ruby/library/net-http/httpheader/fixtures/classes.rb
diff --git a/spec/ruby/library/net-http/httpheader/form_data_spec.rb b/spec/ruby/library/net-http/httpheader/form_data_spec.rb
new file mode 100644
index 0000000000..acd913f53a
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/form_data_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_form_data'
+
+describe "Net::HTTPHeader#form_data=" do
+  it_behaves_like :net_httpheader_set_form_data, :form_data=
+end
diff --git a/spec/ruby/library/net-http/httpheader/get_fields_spec.rb b/spec/ruby/library/net-http/httpheader/get_fields_spec.rb
new file mode 100644
index 0000000000..76da63bc31
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/get_fields_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#get_fields when passed key" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns an Array containing the values of the header entry with the passed key" do
+    @headers["My-Header"] = "a"
+    @headers.get_fields("My-Header").should == ["a"]
+
+    @headers.add_field("My-Header", "b")
+    @headers.get_fields("My-Header").should == ["a", "b"]
+  end
+
+  it "returns a copy of the header entry values" do
+    @headers["My-Header"] = "a"
+
+    @headers.get_fields("My-Header").clear
+    @headers.get_fields("My-Header").should == ["a"]
+
+    @headers.get_fields("My-Header") << "b"
+    @headers.get_fields("My-Header").should == ["a"]
+  end
+
+  it "returns nil for non-existing header entries" do
+    @headers.get_fields("My-Header").should == nil
+    @headers.get_fields("My-Other-header").should == nil
+  end
+
+  it "is case-insensitive" do
+    @headers["My-Header"] = "test"
+    @headers.get_fields("My-Header").should == ["test"]
+    @headers.get_fields("my-header").should == ["test"]
+    @headers.get_fields("MY-HEADER").should == ["test"]
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/initialize_http_header_spec.rb b/spec/ruby/library/net-http/httpheader/initialize_http_header_spec.rb
new file mode 100644
index 0000000000..f9e6d208e5
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/initialize_http_header_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#initialize_http_header when passed Hash" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.allocate
+  end
+
+  it "initializes the HTTP Header using the passed Hash" do
+    @headers.initialize_http_header("My-Header" => "test", "My-Other-Header" => "another test")
+    @headers["My-Header"].should == "test"
+    @headers["My-Other-Header"].should == "another test"
+  end
+
+  it "complains about duplicate keys when in verbose mode" do
+    -> do
+      @headers.initialize_http_header("My-Header" => "test", "my-header" => "another test")
+    end.should complain(/duplicated HTTP header/, verbose: true)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/key_spec.rb b/spec/ruby/library/net-http/httpheader/key_spec.rb
new file mode 100644
index 0000000000..65662591eb
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/key_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#key? when passed key" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns true if the header entry with the passed key exists" do
+    @headers.key?("My-Header").should == false
+    @headers["My-Header"] = "test"
+    @headers.key?("My-Header").should == true
+  end
+
+  it "is case-insensitive" do
+    @headers["My-Header"] = "test"
+    @headers.key?("my-header").should == true
+    @headers.key?("MY-HEADER").should == true
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/length_spec.rb b/spec/ruby/library/net-http/httpheader/length_spec.rb
new file mode 100644
index 0000000000..57e32742e4
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/length_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/size'
+
+describe "Net::HTTPHeader#length" do
+  it_behaves_like :net_httpheader_size, :length
+end
diff --git a/spec/ruby/library/net-http/httpheader/main_type_spec.rb b/spec/ruby/library/net-http/httpheader/main_type_spec.rb
new file mode 100644
index 0000000000..af7d3e05a3
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/main_type_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#main_type" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the 'main-content-type', as per 'Content-Type' header entry" do
+    @headers["Content-Type"] = "text/html"
+    @headers.main_type.should == "text"
+
+    @headers["Content-Type"] = "application/pdf"
+    @headers.main_type.should == "application"
+
+    @headers["Content-Type"] = "text/html;charset=utf-8"
+    @headers.main_type.should == "text"
+  end
+
+  it "returns nil if the 'Content-Type' header entry does not exist" do
+    @headers.main_type.should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/proxy_basic_auth_spec.rb b/spec/ruby/library/net-http/httpheader/proxy_basic_auth_spec.rb
new file mode 100644
index 0000000000..d9f6afc5a7
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/proxy_basic_auth_spec.rb
@@ -0,0 +1,14 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#proxy_basic_auth when passed account, password" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "sets the 'Proxy-Authorization' Header entry for basic authorization" do
+    @headers.proxy_basic_auth("rubyspec", "rocks")
+    @headers["Proxy-Authorization"].should == "Basic cnVieXNwZWM6cm9ja3M="
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/range_length_spec.rb b/spec/ruby/library/net-http/httpheader/range_length_spec.rb
new file mode 100644
index 0000000000..34db7e6126
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/range_length_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#range_length" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the length of the Range represented by the 'Content-Range' header entry" do
+    @headers["Content-Range"] = "bytes 0-499/1234"
+    @headers.range_length.should.eql?(500)
+
+    @headers["Content-Range"] = "bytes 500-1233/1234"
+    @headers.range_length.should.eql?(734)
+  end
+
+  it "returns nil when there is no 'Content-Range' header entry" do
+    @headers.range_length.should == nil
+  end
+
+  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Range' has an invalid format" do
+    @headers["Content-Range"] = "invalid"
+    -> { @headers.range_length }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Content-Range"] = "bytes 123-abc"
+    -> { @headers.range_length }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Content-Range"] = "bytes abc-123"
+    -> { @headers.range_length }.should.raise(Net::HTTPHeaderSyntaxError)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/range_spec.rb b/spec/ruby/library/net-http/httpheader/range_spec.rb
new file mode 100644
index 0000000000..0fc0feb5c9
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/range_spec.rb
@@ -0,0 +1,48 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_range'
+
+describe "Net::HTTPHeader#range" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns a Range object that represents the 'Range' header entry" do
+    @headers["Range"] = "bytes=0-499"
+    @headers.range.should == [0..499]
+
+    @headers["Range"] = "bytes=500-1233"
+    @headers.range.should == [500..1233]
+
+    @headers["Range"] = "bytes=10-"
+    @headers.range.should == [10..-1]
+
+    @headers["Range"] = "bytes=-10"
+    @headers.range.should == [-10..-1]
+  end
+
+  it "returns nil when there is no 'Range' header entry" do
+    @headers.range.should == nil
+  end
+
+  it "raises a Net::HTTPHeaderSyntaxError when the 'Range' has an invalid format" do
+    @headers["Range"] = "invalid"
+    -> { @headers.range }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Range"] = "bytes 123-abc"
+    -> { @headers.range }.should.raise(Net::HTTPHeaderSyntaxError)
+
+    @headers["Range"] = "bytes abc-123"
+    -> { @headers.range }.should.raise(Net::HTTPHeaderSyntaxError)
+  end
+
+  it "raises a Net::HTTPHeaderSyntaxError when the 'Range' was not specified" do
+    @headers["Range"] = "bytes=-"
+    -> { @headers.range }.should.raise(Net::HTTPHeaderSyntaxError)
+  end
+end
+
+describe "Net::HTTPHeader#range=" do
+  it_behaves_like :net_httpheader_set_range, :range=
+end
diff --git a/spec/ruby/library/net-http/httpheader/set_content_type_spec.rb b/spec/ruby/library/net-http/httpheader/set_content_type_spec.rb
new file mode 100644
index 0000000000..7ec4f90b8e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/set_content_type_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_content_type'
+
+describe "Net::HTTPHeader#set_content_type" do
+  it_behaves_like :net_httpheader_set_content_type, :set_content_type
+end
diff --git a/spec/ruby/library/net-http/httpheader/set_form_data_spec.rb b/spec/ruby/library/net-http/httpheader/set_form_data_spec.rb
new file mode 100644
index 0000000000..7aac19f045
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/set_form_data_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_form_data'
+
+describe "Net::HTTPHeader#set_form_data" do
+  it_behaves_like :net_httpheader_set_form_data, :set_form_data
+end
diff --git a/spec/ruby/library/net-http/httpheader/set_range_spec.rb b/spec/ruby/library/net-http/httpheader/set_range_spec.rb
new file mode 100644
index 0000000000..0f98de55e6
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/set_range_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/set_range'
+
+describe "Net::HTTPHeader#set_range" do
+  it_behaves_like :net_httpheader_set_range, :set_range
+end
diff --git a/spec/ruby/library/net-http/httpheader/shared/each_capitalized.rb b/spec/ruby/library/net-http/httpheader/shared/each_capitalized.rb
new file mode 100644
index 0000000000..c12df62787
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/shared/each_capitalized.rb
@@ -0,0 +1,31 @@
+describe :net_httpheader_each_capitalized, shared: true do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+    @headers["my-header"] = "test"
+    @headers.add_field("my-Other-Header", "a")
+    @headers.add_field("My-Other-header", "b")
+  end
+
+  describe "when passed a block" do
+    it "yields each header entry to the passed block (capitalized keys, values joined)" do
+      res = []
+      @headers.send(@method) do |key, value|
+        res << [key, value]
+      end
+      res.sort.should == [["My-Header", "test"], ["My-Other-Header", "a, b"]]
+    end
+  end
+
+  describe "when passed no block" do
+    it "returns an Enumerator" do
+      enumerator = @headers.send(@method)
+      enumerator.should.instance_of?(Enumerator)
+
+      res = []
+      enumerator.each do |*key|
+        res << key
+      end
+      res.sort.should == [["My-Header", "test"], ["My-Other-Header", "a, b"]]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/shared/each_header.rb b/spec/ruby/library/net-http/httpheader/shared/each_header.rb
new file mode 100644
index 0000000000..5913665a4d
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/shared/each_header.rb
@@ -0,0 +1,31 @@
+describe :net_httpheader_each_header, shared: true do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+    @headers["My-Header"] = "test"
+    @headers.add_field("My-Other-Header", "a")
+    @headers.add_field("My-Other-Header", "b")
+  end
+
+  describe "when passed a block" do
+    it "yields each header entry to the passed block (keys in lower case, values joined)" do
+      res = []
+      @headers.send(@method) do |key, value|
+        res << [key, value]
+      end
+      res.sort.should == [["my-header", "test"], ["my-other-header", "a, b"]]
+    end
+  end
+
+  describe "when passed no block" do
+    it "returns an Enumerator" do
+      enumerator = @headers.send(@method)
+      enumerator.should.instance_of?(Enumerator)
+
+      res = []
+      enumerator.each do |*key|
+        res << key
+      end
+      res.sort.should == [["my-header", "test"], ["my-other-header", "a, b"]]
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/shared/each_name.rb b/spec/ruby/library/net-http/httpheader/shared/each_name.rb
new file mode 100644
index 0000000000..29c9400fef
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/shared/each_name.rb
@@ -0,0 +1,31 @@
+describe :net_httpheader_each_name, shared: true do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+    @headers["My-Header"] = "test"
+    @headers.add_field("My-Other-Header", "a")
+    @headers.add_field("My-Other-Header", "b")
+  end
+
+  describe "when passed a block" do
+    it "yields each header key to the passed block (keys in lower case)" do
+      res = []
+      @headers.send(@method) do |key|
+        res << key
+      end
+      res.sort.should == ["my-header", "my-other-header"]
+    end
+  end
+
+  describe "when passed no block" do
+    it "returns an Enumerator" do
+      enumerator = @headers.send(@method)
+      enumerator.should.instance_of?(Enumerator)
+
+      res = []
+      enumerator.each do |key|
+        res << key
+      end
+      res.sort.should == ["my-header", "my-other-header"]
+    end
+  end
+end
diff --git a/spec/ruby/library/net/http/httpheader/shared/set_content_type.rb b/spec/ruby/library/net-http/httpheader/shared/set_content_type.rb
index b7359bdca6..b7359bdca6 100644
--- a/spec/ruby/library/net/http/httpheader/shared/set_content_type.rb
+++ b/spec/ruby/library/net-http/httpheader/shared/set_content_type.rb
diff --git a/spec/ruby/library/net/http/httpheader/shared/set_form_data.rb b/spec/ruby/library/net-http/httpheader/shared/set_form_data.rb
index db20b18803..db20b18803 100644
--- a/spec/ruby/library/net/http/httpheader/shared/set_form_data.rb
+++ b/spec/ruby/library/net-http/httpheader/shared/set_form_data.rb
diff --git a/spec/ruby/library/net-http/httpheader/shared/set_range.rb b/spec/ruby/library/net-http/httpheader/shared/set_range.rb
new file mode 100644
index 0000000000..9ab50a075e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/shared/set_range.rb
@@ -0,0 +1,89 @@
+describe :net_httpheader_set_range, shared: true do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  describe "when passed nil" do
+    it "returns nil" do
+      @headers.send(@method, nil).should == nil
+    end
+
+    it "deletes the 'Range' header entry" do
+      @headers["Range"] = "bytes 0-499/1234"
+      @headers.send(@method, nil)
+      @headers["Range"].should == nil
+    end
+  end
+
+  describe "when passed Numeric" do
+    it "sets the 'Range' header entry based on the passed Numeric" do
+      @headers.send(@method, 10)
+      @headers["Range"].should == "bytes=0-9"
+
+      @headers.send(@method, -10)
+      @headers["Range"].should == "bytes=-10"
+
+      @headers.send(@method, 10.9)
+      @headers["Range"].should == "bytes=0-9"
+    end
+  end
+
+  describe "when passed Range" do
+    it "sets the 'Range' header entry based on the passed Range" do
+      @headers.send(@method, 10..200)
+      @headers["Range"].should == "bytes=10-200"
+
+      @headers.send(@method, 1..5)
+      @headers["Range"].should == "bytes=1-5"
+
+      @headers.send(@method, 1...5)
+      @headers["Range"].should == "bytes=1-4"
+
+      @headers.send(@method, 234..567)
+      @headers["Range"].should == "bytes=234-567"
+
+      @headers.send(@method, -5..-1)
+      @headers["Range"].should == "bytes=-5"
+
+      @headers.send(@method, 1..-1)
+      @headers["Range"].should == "bytes=1-"
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when the first Range element is negative" do
+      -> { @headers.send(@method, -10..5) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when the last Range element is negative" do
+      -> { @headers.send(@method, 10..-5) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when the last Range element is smaller than the first" do
+      -> { @headers.send(@method, 10..5) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+  end
+
+  describe "when passed start, end" do
+    it "sets the 'Range' header entry based on the passed start and length values" do
+      @headers.send(@method, 10, 200)
+      @headers["Range"].should == "bytes=10-209"
+
+      @headers.send(@method, 1, 5)
+      @headers["Range"].should == "bytes=1-5"
+
+      @headers.send(@method, 234, 567)
+      @headers["Range"].should == "bytes=234-800"
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when start is negative" do
+      -> { @headers.send(@method, -10, 5) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when start + length is negative" do
+      -> { @headers.send(@method, 10, -15) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+
+    it "raises a Net::HTTPHeaderSyntaxError when length is negative" do
+      -> { @headers.send(@method, 10, -4) }.should.raise(Net::HTTPHeaderSyntaxError)
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/shared/size.rb b/spec/ruby/library/net-http/httpheader/shared/size.rb
new file mode 100644
index 0000000000..b38310a940
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/shared/size.rb
@@ -0,0 +1,18 @@
+describe :net_httpheader_size, shared: true do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the number of header entries in self" do
+    @headers.send(@method).should.eql?(0)
+
+    @headers["a"] = "b"
+    @headers.send(@method).should.eql?(1)
+
+    @headers["b"] = "b"
+    @headers.send(@method).should.eql?(2)
+
+    @headers["c"] = "c"
+    @headers.send(@method).should.eql?(3)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/size_spec.rb b/spec/ruby/library/net-http/httpheader/size_spec.rb
new file mode 100644
index 0000000000..210060ce21
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/size_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+require_relative 'shared/size'
+
+describe "Net::HTTPHeader#size" do
+  it_behaves_like :net_httpheader_size, :size
+end
diff --git a/spec/ruby/library/net-http/httpheader/sub_type_spec.rb b/spec/ruby/library/net-http/httpheader/sub_type_spec.rb
new file mode 100644
index 0000000000..9e7d2a5368
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/sub_type_spec.rb
@@ -0,0 +1,32 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#sub_type" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns the 'sub-content-type', as per 'Content-Type' header entry" do
+    @headers["Content-Type"] = "text/html"
+    @headers.sub_type.should == "html"
+
+    @headers["Content-Type"] = "application/pdf"
+    @headers.sub_type.should == "pdf"
+
+    @headers["Content-Type"] = "text/html;charset=utf-8"
+    @headers.sub_type.should == "html"
+  end
+
+  it "returns nil if no 'sub-content-type' is set" do
+    @headers["Content-Type"] = "text"
+    @headers.sub_type.should == nil
+
+    @headers["Content-Type"] = "text;charset=utf-8"
+    @headers.sub_type.should == nil
+  end
+
+  it "returns nil if the 'Content-Type' header entry does not exist" do
+    @headers.sub_type.should == nil
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/to_hash_spec.rb b/spec/ruby/library/net-http/httpheader/to_hash_spec.rb
new file mode 100644
index 0000000000..e245c20d4c
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/to_hash_spec.rb
@@ -0,0 +1,25 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#to_hash" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns a Hash representing all Header entries (keys in lower case, values as arrays)" do
+    @headers.to_hash.should == {}
+
+    @headers["My-Header"] = "test"
+    @headers.to_hash.should == { "my-header" => ["test"] }
+
+    @headers.add_field("My-Header", "another test")
+    @headers.to_hash.should == { "my-header" => ["test", "another test"] }
+  end
+
+  it "does not allow modifying the headers from the returned hash" do
+    @headers.to_hash["my-header"] = ["test"]
+    @headers.to_hash.should == {}
+    @headers.key?("my-header").should == false
+  end
+end
diff --git a/spec/ruby/library/net-http/httpheader/type_params_spec.rb b/spec/ruby/library/net-http/httpheader/type_params_spec.rb
new file mode 100644
index 0000000000..ac97e2b48c
--- /dev/null
+++ b/spec/ruby/library/net-http/httpheader/type_params_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'fixtures/classes'
+
+describe "Net::HTTPHeader#type_params" do
+  before :each do
+    @headers = NetHTTPHeaderSpecs::Example.new
+  end
+
+  it "returns additional 'Content-Type' information as a Hash" do
+    @headers["Content-Type"] = "text/html;charset=utf-8"
+    @headers.type_params.should == {"charset" => "utf-8"}
+
+    @headers["Content-Type"] = "text/html; charset=utf-8; rubyspec=rocks"
+    @headers.type_params.should == {"charset" => "utf-8", "rubyspec" => "rocks"}
+  end
+
+  it "returns an empty Hash when no additional 'Content-Type' information is set" do
+    @headers.type_params.should == {}
+
+    @headers["Content-Type"] = "text/html"
+    @headers.type_params.should == {}
+  end
+end
diff --git a/spec/ruby/library/net-http/httprequest/initialize_spec.rb b/spec/ruby/library/net-http/httprequest/initialize_spec.rb
new file mode 100644
index 0000000000..1229986bef
--- /dev/null
+++ b/spec/ruby/library/net-http/httprequest/initialize_spec.rb
@@ -0,0 +1,45 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+module NetHTTPRequestSpecs
+  class TestRequest < Net::HTTPRequest
+    METHOD = "TEST"
+    REQUEST_HAS_BODY  = false
+    RESPONSE_HAS_BODY = true
+  end
+end
+
+describe "Net::HTTPRequest#initialize" do
+  before :each do
+    @req = NetHTTPRequestSpecs::TestRequest.allocate
+  end
+
+  it "uses the METHOD constants to set the request method" do
+    @req.send(:initialize, "/some/path")
+    @req.method.should == "TEST"
+  end
+
+  it "uses the REQUEST_HAS_BODY to set whether the Request has a body or not" do
+    @req.send(:initialize, "/some/path")
+    @req.request_body_permitted?.should == false
+  end
+
+  it "uses the RESPONSE_HAS_BODY to set whether the Response can have a body or not" do
+    @req.send(:initialize, "/some/path")
+    @req.response_body_permitted?.should == true
+  end
+
+  describe "when passed path" do
+    it "sets self's path to the passed path" do
+      @req.send(:initialize, "/some/path")
+      @req.path.should == "/some/path"
+    end
+  end
+
+  describe "when passed path, headers" do
+    it "uses the passed headers Hash to initialize self's header entries" do
+      @req.send(:initialize, "/some/path", "Content-Type" => "text/html")
+      @req["Content-Type"].should == "text/html"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/body_permitted_spec.rb b/spec/ruby/library/net-http/httpresponse/body_permitted_spec.rb
new file mode 100644
index 0000000000..68965de4a1
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/body_permitted_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse.body_permitted?" do
+  it "returns true if this response type can have a response body" do
+    Net::HTTPUnknownResponse.should.body_permitted?
+    Net::HTTPInformation.should_not.body_permitted?
+    Net::HTTPSuccess.should.body_permitted?
+    Net::HTTPRedirection.should.body_permitted?
+    Net::HTTPClientError.should.body_permitted?
+    Net::HTTPServerError.should.body_permitted?
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/body_spec.rb b/spec/ruby/library/net-http/httpresponse/body_spec.rb
new file mode 100644
index 0000000000..ddfcd834c4
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/body_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/body'
+
+describe "Net::HTTPResponse#body" do
+  it_behaves_like :net_httpresponse_body, :body
+end
diff --git a/spec/ruby/library/net-http/httpresponse/code_spec.rb b/spec/ruby/library/net-http/httpresponse/code_spec.rb
new file mode 100644
index 0000000000..699062ad97
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/code_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#code" do
+  it "returns the result code string" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.code.should == "???"
+
+    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
+    res.code.should == "1xx"
+
+    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
+    res.code.should == "2xx"
+
+    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
+    res.code.should == "3xx"
+
+    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
+    res.code.should == "4xx"
+
+    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
+    res.code.should == "5xx"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/code_type_spec.rb b/spec/ruby/library/net-http/httpresponse/code_type_spec.rb
new file mode 100644
index 0000000000..beb661cbbe
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/code_type_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#code_type" do
+  it "returns self's class" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.code_type.should == Net::HTTPUnknownResponse
+
+    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
+    res.code_type.should == Net::HTTPInformation
+
+    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
+    res.code_type.should == Net::HTTPSuccess
+
+    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
+    res.code_type.should == Net::HTTPRedirection
+
+    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
+    res.code_type.should == Net::HTTPClientError
+
+    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
+    res.code_type.should == Net::HTTPServerError
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/entity_spec.rb b/spec/ruby/library/net-http/httpresponse/entity_spec.rb
new file mode 100644
index 0000000000..ca8c4b29c0
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/entity_spec.rb
@@ -0,0 +1,7 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require_relative 'shared/body'
+
+describe "Net::HTTPResponse#entity" do
+  it_behaves_like :net_httpresponse_body, :entity
+end
diff --git a/spec/ruby/library/net-http/httpresponse/error_spec.rb b/spec/ruby/library/net-http/httpresponse/error_spec.rb
new file mode 100644
index 0000000000..e194df95af
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/error_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#error!" do
+  it "raises self's class 'EXCEPTION_TYPE' Exception" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    -> { res.error! }.should.raise(Net::HTTPError)
+
+    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
+    -> { res.error! }.should.raise(Net::HTTPError)
+
+    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
+    -> { res.error! }.should.raise(Net::HTTPError)
+
+    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
+    -> { res.error! }.should.raise(Net::HTTPRetriableError)
+
+    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
+    -> { res.error! }.should.raise(Net::HTTPClientException)
+
+    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
+    -> { res.error! }.should.raise(Net::HTTPFatalError)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/error_type_spec.rb b/spec/ruby/library/net-http/httpresponse/error_type_spec.rb
new file mode 100644
index 0000000000..3969621a5e
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/error_type_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#error_type" do
+  it "returns self's class 'EXCEPTION_TYPE' constant" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.error_type.should == Net::HTTPError
+
+    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
+    res.error_type.should == Net::HTTPError
+
+    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
+    res.error_type.should == Net::HTTPError
+
+    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
+    res.error_type.should == Net::HTTPRetriableError
+
+    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
+    res.error_type.should == Net::HTTPClientException
+
+    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
+    res.error_type.should == Net::HTTPFatalError
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/exception_type_spec.rb b/spec/ruby/library/net-http/httpresponse/exception_type_spec.rb
new file mode 100644
index 0000000000..dd2761a744
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/exception_type_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse.exception_type" do
+  it "returns self's 'EXCEPTION_TYPE' constant" do
+    Net::HTTPUnknownResponse.exception_type.should == Net::HTTPError
+    Net::HTTPInformation.exception_type.should == Net::HTTPError
+    Net::HTTPSuccess.exception_type.should == Net::HTTPError
+    Net::HTTPRedirection.exception_type.should == Net::HTTPRetriableError
+    Net::HTTPClientError.exception_type.should == Net::HTTPClientException
+    Net::HTTPServerError.exception_type.should == Net::HTTPFatalError
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/header_spec.rb b/spec/ruby/library/net-http/httpresponse/header_spec.rb
new file mode 100644
index 0000000000..3ddadfb8e4
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/header_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#header" do
+  it "returns self" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.response.should.equal?(res)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/http_version_spec.rb b/spec/ruby/library/net-http/httpresponse/http_version_spec.rb
new file mode 100644
index 0000000000..a3e413a360
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/http_version_spec.rb
@@ -0,0 +1,12 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#http_version" do
+  it "returns self's http version" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.http_version.should == "1.0"
+
+    res = Net::HTTPUnknownResponse.new("1.1", "???", "test response")
+    res.http_version.should == "1.1"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/initialize_spec.rb b/spec/ruby/library/net-http/httpresponse/initialize_spec.rb
new file mode 100644
index 0000000000..673c11a245
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/initialize_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#initialize when passed http_version, response_code, response_message" do
+  it "sets self http_version, response_code and response_message to the passed values" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.http_version.should == "1.0"
+    res.code.should == "???"
+    res.message.should == "test response"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/inspect_spec.rb b/spec/ruby/library/net-http/httpresponse/inspect_spec.rb
new file mode 100644
index 0000000000..43071ec8cd
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/inspect_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+
+describe "Net::HTTPResponse#inspect" do
+  it "returns a String representation of self" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=false>"
+
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    socket = Net::BufferedIO.new(StringIO.new("test body"))
+    res.reading_body(socket, true) {}
+    res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=true>"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/message_spec.rb b/spec/ruby/library/net-http/httpresponse/message_spec.rb
new file mode 100644
index 0000000000..5ba73bb449
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/message_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#message" do
+  it "returns self's response message" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.message.should == "test response"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/msg_spec.rb b/spec/ruby/library/net-http/httpresponse/msg_spec.rb
new file mode 100644
index 0000000000..04f5836d7a
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/msg_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#msg" do
+  it "returns self's response message" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.message.should == "test response"
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/read_body_spec.rb b/spec/ruby/library/net-http/httpresponse/read_body_spec.rb
new file mode 100644
index 0000000000..d8b2418624
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/read_body_spec.rb
@@ -0,0 +1,86 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require 'stringio'
+
+describe "Net::HTTPResponse#read_body" do
+  before :each do
+    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    @socket = Net::BufferedIO.new(StringIO.new("test body"))
+  end
+
+  describe "when passed no arguments" do
+    it "returns the read body" do
+      @res.reading_body(@socket, true) do
+        @res.read_body.should == "test body"
+      end
+    end
+
+    it "returns the previously read body if called a second time" do
+      @res.reading_body(@socket, true) do
+        @res.read_body.should.equal?(@res.read_body)
+      end
+    end
+  end
+
+  describe "when passed a buffer" do
+    it "reads the body to the passed buffer" do
+      @res.reading_body(@socket, true) do
+        buffer = +""
+        @res.read_body(buffer)
+        buffer.should == "test body"
+      end
+    end
+
+    it "returns the passed buffer" do
+      @res.reading_body(@socket, true) do
+        buffer = +""
+        @res.read_body(buffer).should.equal?(buffer)
+      end
+    end
+
+    it "raises an IOError if called a second time" do
+      @res.reading_body(@socket, true) do
+        @res.read_body(+"")
+        -> { @res.read_body(+"") }.should.raise(IOError)
+      end
+    end
+  end
+
+  describe "when passed a block" do
+    it "reads the body and yields it to the passed block (in chunks)" do
+      @res.reading_body(@socket, true) do
+        yielded = false
+
+        buffer = +""
+        @res.read_body do |body|
+          yielded = true
+          buffer << body
+        end
+
+        yielded.should == true
+        buffer.should == "test body"
+      end
+    end
+
+    it "returns the ReadAdapter" do
+      @res.reading_body(@socket, true) do
+        @res.read_body { nil }.should.is_a?(Net::ReadAdapter)
+      end
+    end
+
+    it "raises an IOError if called a second time" do
+      @res.reading_body(@socket, true) do
+        @res.read_body {}
+        -> { @res.read_body {} }.should.raise(IOError)
+      end
+    end
+  end
+
+  describe "when passed buffer and block" do
+    it "raises an ArgumentError" do
+      @res.reading_body(@socket, true) do
+        -> { @res.read_body(+"") {} }.should.raise(ArgumentError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/read_header_spec.rb b/spec/ruby/library/net-http/httpresponse/read_header_spec.rb
new file mode 100644
index 0000000000..70ce988502
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/read_header_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#read_header" do
+  it "returns self" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.response.should.equal?(res)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/read_new_spec.rb b/spec/ruby/library/net-http/httpresponse/read_new_spec.rb
new file mode 100644
index 0000000000..3795e29d83
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/read_new_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require 'stringio'
+
+describe "Net::HTTPResponse.read_new" do
+  it "creates a HTTPResponse object based on the response read from the passed socket" do
+    socket = Net::BufferedIO.new(StringIO.new(<<EOS))
+HTTP/1.1 200 OK
+Content-Type: text/html; charset=utf-8
+
+test-body
+EOS
+    response = Net::HTTPResponse.read_new(socket)
+
+    response.should.is_a?(Net::HTTPOK)
+    response.code.should == "200"
+    response["Content-Type"].should == "text/html; charset=utf-8"
+
+    response.reading_body(socket, true) do
+      response.body.should == "test-body\n"
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/reading_body_spec.rb b/spec/ruby/library/net-http/httpresponse/reading_body_spec.rb
new file mode 100644
index 0000000000..a3671d6eb5
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/reading_body_spec.rb
@@ -0,0 +1,58 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+require "stringio"
+
+describe "Net::HTTPResponse#reading_body" do
+  before :each do
+    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    @socket = Net::BufferedIO.new(StringIO.new("test body"))
+  end
+
+  describe "when body_allowed is true" do
+    it "reads and returns the response body for self from the passed socket" do
+      @res.reading_body(@socket, true) {}.should == "test body"
+      @res.body.should == "test body"
+    end
+
+    it "yields the passed block before reading the body" do
+      yielded = false
+
+      @res.reading_body(@socket, true) do
+        @res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=false>"
+        yielded = true
+      end
+
+      yielded.should == true
+    end
+
+    describe "but the response type is not allowed to have a body" do
+      before :each do
+        @res = Net::HTTPInformation.new("1.0", "???", "test response")
+      end
+
+      it "returns nil" do
+        @res.reading_body(@socket, false) {}.should == nil
+        @res.body.should == nil
+      end
+
+      it "yields the passed block" do
+        yielded = false
+        @res.reading_body(@socket, true) { yielded = true }
+        yielded.should == true
+      end
+    end
+  end
+
+  describe "when body_allowed is false" do
+    it "returns nil" do
+      @res.reading_body(@socket, false) {}.should == nil
+      @res.body.should == nil
+    end
+
+    it "yields the passed block" do
+      yielded = false
+      @res.reading_body(@socket, true) { yielded = true }
+      yielded.should == true
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/response_spec.rb b/spec/ruby/library/net-http/httpresponse/response_spec.rb
new file mode 100644
index 0000000000..440c33c168
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/response_spec.rb
@@ -0,0 +1,9 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#response" do
+  it "returns self" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    res.response.should.equal?(res)
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/shared/body.rb b/spec/ruby/library/net-http/httpresponse/shared/body.rb
new file mode 100644
index 0000000000..368774fb52
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/shared/body.rb
@@ -0,0 +1,20 @@
+require 'stringio'
+
+describe :net_httpresponse_body, shared: true do
+  before :each do
+    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    @socket = Net::BufferedIO.new(StringIO.new("test body"))
+  end
+
+  it "returns the read body" do
+    @res.reading_body(@socket, true) do
+      @res.send(@method).should == "test body"
+    end
+  end
+
+  it "returns the previously read body if called a second time" do
+    @res.reading_body(@socket, true) do
+      @res.send(@method).should.equal?(@res.send(@method))
+    end
+  end
+end
diff --git a/spec/ruby/library/net-http/httpresponse/value_spec.rb b/spec/ruby/library/net-http/httpresponse/value_spec.rb
new file mode 100644
index 0000000000..e32d37500a
--- /dev/null
+++ b/spec/ruby/library/net-http/httpresponse/value_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../../../spec_helper'
+require 'net/http'
+
+describe "Net::HTTPResponse#value" do
+  it "raises an HTTP error for non 2xx HTTP Responses" do
+    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
+    -> { res.value }.should.raise(Net::HTTPError)
+
+    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
+    -> { res.value }.should.raise(Net::HTTPError)
+
+    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
+    -> { res.value }.should_not.raise(Net::HTTPError)
+
+    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
+    -> { res.value }.should.raise(Net::HTTPRetriableError)
+
+    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
+    -> { res.value }.should.raise(Net::HTTPClientException)
+
+    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
+    -> { res.value }.should.raise(Net::HTTPFatalError)
+  end
+end
diff --git a/spec/ruby/library/net/FTPError_spec.rb b/spec/ruby/library/net/FTPError_spec.rb
deleted file mode 100644
index 0c31b65dcc..0000000000
--- a/spec/ruby/library/net/FTPError_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../spec_helper'
-require 'net/ftp'
-
-describe "Net::FTPError" do
-  it "is an Exception" do
-    Net::FTPError.should < Exception
-  end
-end
diff --git a/spec/ruby/library/net/FTPPermError_spec.rb b/spec/ruby/library/net/FTPPermError_spec.rb
deleted file mode 100644
index b43e12c503..0000000000
--- a/spec/ruby/library/net/FTPPermError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-require 'net/ftp'
-
-describe "Net::FTPPermError" do
-  it "is an Exception" do
-    Net::FTPPermError.should < Exception
-  end
-
-  it "is a subclass of Net::FTPError" do
-    Net::FTPPermError.should < Net::FTPError
-  end
-end
diff --git a/spec/ruby/library/net/FTPProtoError_spec.rb b/spec/ruby/library/net/FTPProtoError_spec.rb
deleted file mode 100644
index e7abbc0dd8..0000000000
--- a/spec/ruby/library/net/FTPProtoError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-require 'net/ftp'
-
-describe "Net::FTPProtoError" do
-  it "is an Exception" do
-    Net::FTPProtoError.should < Exception
-  end
-
-  it "is a subclass of Net::FTPError" do
-    Net::FTPPermError.should < Net::FTPError
-  end
-end
diff --git a/spec/ruby/library/net/FTPReplyError_spec.rb b/spec/ruby/library/net/FTPReplyError_spec.rb
deleted file mode 100644
index fcc7501fc1..0000000000
--- a/spec/ruby/library/net/FTPReplyError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-require 'net/ftp'
-
-describe "Net::FTPReplyError" do
-  it "is an Exception" do
-    Net::FTPReplyError.should < Exception
-  end
-
-  it "is a subclass of Net::FTPError" do
-    Net::FTPPermError.should < Net::FTPError
-  end
-end
diff --git a/spec/ruby/library/net/FTPTempError_spec.rb b/spec/ruby/library/net/FTPTempError_spec.rb
deleted file mode 100644
index f4b045dfb5..0000000000
--- a/spec/ruby/library/net/FTPTempError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../spec_helper'
-require 'net/ftp'
-
-describe "Net::FTPTempError" do
-  it "is an Exception" do
-    Net::FTPTempError.should < Exception
-  end
-
-  it "is a subclass of Net::FTPError" do
-    Net::FTPPermError.should < Net::FTPError
-  end
-end
diff --git a/spec/ruby/library/net/ftp/abort_spec.rb b/spec/ruby/library/net/ftp/abort_spec.rb
deleted file mode 100644
index 57651468d8..0000000000
--- a/spec/ruby/library/net/ftp/abort_spec.rb
+++ /dev/null
@@ -1,62 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#abort" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the ABOR command to the server" do
-    -> { @ftp.abort }.should_not raise_error
-  end
-
-  it "ignores the response" do
-    @ftp.abort
-    @ftp.last_response.should == "220 Dummy FTP Server ready!\n"
-  end
-
-  it "returns the full response" do
-    @ftp.abort.should == "226 Closing data connection. (ABOR)\n"
-  end
-
-  it "does not raise any error when the response code is 225" do
-    @server.should_receive(:abor).and_respond("225 Data connection open; no transfer in progress.")
-    -> { @ftp.abort }.should_not raise_error
-  end
-
-  it "does not raise any error when the response code is 226" do
-    @server.should_receive(:abor).and_respond("226 Closing data connection.")
-    -> { @ftp.abort }.should_not raise_error
-  end
-
-  it "raises a Net::FTPProtoError when the response code is 500" do
-    @server.should_receive(:abor).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.abort }.should raise_error(Net::FTPProtoError)
-  end
-
-  it "raises a Net::FTPProtoError when the response code is 501" do
-    @server.should_receive(:abor).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.abort }.should raise_error(Net::FTPProtoError)
-  end
-
-  it "raises a Net::FTPProtoError when the response code is 502" do
-    @server.should_receive(:abor).and_respond("502 Command not implemented.")
-    -> { @ftp.abort }.should raise_error(Net::FTPProtoError)
-  end
-
-  it "raises a Net::FTPProtoError when the response code is 421" do
-    @server.should_receive(:abor).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.abort }.should raise_error(Net::FTPProtoError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/acct_spec.rb b/spec/ruby/library/net/ftp/acct_spec.rb
deleted file mode 100644
index d8068dc81e..0000000000
--- a/spec/ruby/library/net/ftp/acct_spec.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#acct" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "writes the ACCT command to the server" do
-    @ftp.acct("my_account")
-    @ftp.last_response.should == "230 User 'my_account' logged in, proceed. (ACCT)\n"
-  end
-
-  it "returns nil" do
-    @ftp.acct("my_account").should == nil
-  end
-
-  it "does not raise any error when the response code is 230" do
-    @server.should_receive(:acct).and_respond("230 User logged in, proceed.")
-    -> { @ftp.acct("my_account") }.should_not raise_error
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:acct).and_respond("530 Not logged in.")
-    -> { @ftp.acct("my_account") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:acct).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.acct("my_account") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:acct).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.acct("my_account") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 503" do
-    @server.should_receive(:acct).and_respond("503 Bad sequence of commands.")
-    -> { @ftp.acct("my_account") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:acct).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.acct("my_account") }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/binary_spec.rb b/spec/ruby/library/net/ftp/binary_spec.rb
deleted file mode 100644
index 60e312a673..0000000000
--- a/spec/ruby/library/net/ftp/binary_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#binary" do
-  it "returns true when self is in binary mode" do
-    ftp = Net::FTP.new
-    ftp.binary.should be_true
-
-    ftp.binary = false
-    ftp.binary.should be_false
-  end
-end
-
-describe "Net::FTP#binary=" do
-  it "sets self to binary mode when passed true" do
-    ftp = Net::FTP.new
-
-    ftp.binary = true
-    ftp.binary.should be_true
-
-    ftp.binary = false
-    ftp.binary.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/ftp/chdir_spec.rb b/spec/ruby/library/net/ftp/chdir_spec.rb
deleted file mode 100644
index 4c10fa78b4..0000000000
--- a/spec/ruby/library/net/ftp/chdir_spec.rb
+++ /dev/null
@@ -1,99 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#chdir" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  describe "when switching to the parent directory" do
-    it "sends the 'CDUP' command to the server" do
-      @ftp.chdir("..")
-      @ftp.last_response.should == "200 Command okay. (CDUP)\n"
-    end
-
-    it "returns nil" do
-      @ftp.chdir("..").should be_nil
-    end
-
-    it "does not raise a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:cdup).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.chdir("..") }.should_not raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:cdup).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.chdir("..") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:cdup).and_respond("502 Command not implemented.")
-      -> { @ftp.chdir("..") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:cdup).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.chdir("..") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:cdup).and_respond("530 Not logged in.")
-      -> { @ftp.chdir("..") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 550" do
-      @server.should_receive(:cdup).and_respond("550 Requested action not taken.")
-      -> { @ftp.chdir("..") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  it "writes the 'CWD' command with the passed directory to the socket" do
-    @ftp.chdir("test")
-    @ftp.last_response.should == "200 Command okay. (CWD test)\n"
-  end
-
-  it "returns nil" do
-    @ftp.chdir("test").should be_nil
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:cwd).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:cwd).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:cwd).and_respond("502 Command not implemented.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:cwd).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:cwd).and_respond("530 Not logged in.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:cwd).and_respond("550 Requested action not taken.")
-    -> { @ftp.chdir("test") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/close_spec.rb b/spec/ruby/library/net/ftp/close_spec.rb
deleted file mode 100644
index 95c72b29ed..0000000000
--- a/spec/ruby/library/net/ftp/close_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#close" do
-  before :each do
-    @socket = mock("Socket")
-    @socket.stub!(:closed?).and_return(false)
-    @socket.stub!(:read_timeout).and_return(60)
-    @socket.stub!(:read_timeout=).and_return(3)
-
-    @ftp = Net::FTP.new
-    @ftp.instance_variable_set(:@sock, @socket)
-  end
-
-  it "closes the socket" do
-    @socket.should_receive(:close)
-    @ftp.close.should be_nil
-  end
-
-  it "does not try to close the socket if it has already been closed" do
-    @socket.should_receive(:closed?).and_return(true)
-    @socket.should_not_receive(:close)
-    @ftp.close.should be_nil
-  end
-
-  it "does not try to close the socket if it is nil" do
-    @ftp.instance_variable_set(:@sock, nil)
-    @ftp.close.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/ftp/closed_spec.rb b/spec/ruby/library/net/ftp/closed_spec.rb
deleted file mode 100644
index 1f3e69b0c1..0000000000
--- a/spec/ruby/library/net/ftp/closed_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#closed?" do
-  before :each do
-    @socket = mock("Socket")
-
-    @ftp = Net::FTP.new
-    @ftp.instance_variable_set(:@sock, @socket)
-  end
-
-  it "returns true when the socket is closed" do
-    @socket.should_receive(:closed?).and_return(true)
-    @ftp.closed?.should be_true
-  end
-
-  it "returns true when the socket is nil" do
-    @ftp.instance_variable_set(:@sock, nil)
-    @ftp.closed?.should be_true
-  end
-end
diff --git a/spec/ruby/library/net/ftp/connect_spec.rb b/spec/ruby/library/net/ftp/connect_spec.rb
deleted file mode 100644
index 9ee9bcd2c6..0000000000
--- a/spec/ruby/library/net/ftp/connect_spec.rb
+++ /dev/null
@@ -1,49 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-# TODO: Add specs for using the SOCKSSocket
-describe "Net::FTP#connect" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-  end
-
-  after :each do
-    @server.connect_message = nil
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "tries to connect to the FTP Server on the given host and port" do
-    -> { @ftp.connect(@server.hostname, @server.server_port) }.should_not raise_error
-  end
-
-  it "returns nil" do
-    @ftp.connect(@server.hostname, @server.server_port).should be_nil
-  end
-
-  it "prints a small debug line when in debug mode" do
-    @ftp.debug_mode = true
-    -> { @ftp.connect(@server.hostname, @server.server_port) }.should output(/#{"connect: "}#{@server.hostname}#{", "}#{@server.server_port}#{"\\nget: 220 Dummy FTP Server ready!"}/)
-    @ftp.debug_mode = false
-  end
-
-  it "does not raise any error when the response code is 220" do
-    @server.connect_message = "220 Dummy FTP Server ready!"
-    -> { @ftp.connect(@server.hostname, @server.server_port) }.should_not raise_error
-  end
-
-  it "raises a Net::FTPReplyError when the response code is 120" do
-    @server.connect_message = "120 Service ready in nnn minutes."
-    -> { @ftp.connect(@server.hostname, @server.server_port) }.should raise_error(Net::FTPReplyError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.connect_message = "421 Service not available, closing control connection."
-    -> { @ftp.connect(@server.hostname, @server.server_port) }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/debug_mode_spec.rb b/spec/ruby/library/net/ftp/debug_mode_spec.rb
deleted file mode 100644
index f49da55ed1..0000000000
--- a/spec/ruby/library/net/ftp/debug_mode_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#debug_mode" do
-  it "returns true when self is in debug mode" do
-    ftp = Net::FTP.new
-    ftp.debug_mode.should be_false
-
-    ftp.debug_mode = true
-    ftp.debug_mode.should be_true
-  end
-end
-
-describe "Net::FTP#debug_mode=" do
-  it "sets self into debug mode when passed true" do
-    ftp = Net::FTP.new
-    ftp.debug_mode = true
-    ftp.debug_mode.should be_true
-
-    ftp.debug_mode = false
-    ftp.debug_mode.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/ftp/default_passive_spec.rb b/spec/ruby/library/net/ftp/default_passive_spec.rb
deleted file mode 100644
index 30eb8f9da2..0000000000
--- a/spec/ruby/library/net/ftp/default_passive_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#default_passive" do
-  it "is true by default" do
-    ruby_exe(fixture(__FILE__, "default_passive.rb")).should == "true\ntrue\n"
-  end
-end
diff --git a/spec/ruby/library/net/ftp/delete_spec.rb b/spec/ruby/library/net/ftp/delete_spec.rb
deleted file mode 100644
index cf8f9332e2..0000000000
--- a/spec/ruby/library/net/ftp/delete_spec.rb
+++ /dev/null
@@ -1,59 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#delete" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the DELE command with the passed filename to the server" do
-    @ftp.delete("test.file")
-    @ftp.last_response.should == "250 Requested file action okay, completed. (DELE test.file)\n"
-  end
-
-  it "raises a Net::FTPTempError when the response code is 450" do
-    @server.should_receive(:dele).and_respond("450 Requested file action not taken.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:dele).and_respond("550 Requested action not taken.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:dele).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:dele).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:dele).and_respond("502 Command not implemented.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:dele).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:dele).and_respond("530 Not logged in.")
-    -> { @ftp.delete("test.file") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/dir_spec.rb b/spec/ruby/library/net/ftp/dir_spec.rb
deleted file mode 100644
index 47ac7b8d9b..0000000000
--- a/spec/ruby/library/net/ftp/dir_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/list'
-
-describe "Net::FTP#dir" do
-  it_behaves_like :net_ftp_list, :dir
-end
diff --git a/spec/ruby/library/net/ftp/fixtures/server.rb b/spec/ruby/library/net/ftp/fixtures/server.rb
deleted file mode 100644
index d4795a5c58..0000000000
--- a/spec/ruby/library/net/ftp/fixtures/server.rb
+++ /dev/null
@@ -1,277 +0,0 @@
-module NetFTPSpecs
-  class DummyFTP
-    attr_accessor :connect_message
-    attr_reader :login_user, :login_pass, :login_acct
-
-    # hostname or IP address
-    attr_reader :hostname
-    # port number
-    attr_reader :server_port
-
-    def initialize
-      @hostname = "localhost"
-      @server = TCPServer.new(@hostname, 0)
-      @server_port = @server.addr[1]
-
-      @handlers = {}
-      @commands = []
-      @connect_message = nil
-    end
-
-    def serve_once
-      @thread = Thread.new do
-        @socket = @server.accept
-        @socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, 1)
-        begin
-          handle_request
-        ensure
-          @socket.close
-        end
-      end
-    end
-
-    def handle_request
-      # Send out the welcome message.
-      response @connect_message || "220 Dummy FTP Server ready!"
-
-      begin
-        while command = @socket.gets
-          command, argument = command.chomp.split(" ", 2)
-
-          if command == "QUIT"
-            self.response("221 OK, bye")
-            break
-          elsif proc_handler = @handlers[command.downcase.to_sym]
-            if argument.nil?
-              proc_handler.call(self)
-            else
-              proc_handler.call(self, argument)
-            end
-          else
-            if argument.nil?
-              self.send(command.downcase.to_sym)
-            else
-              self.send(command.downcase.to_sym, argument)
-            end
-          end
-        end
-      rescue => e
-        self.error_response("Exception: #{e} #{e.backtrace.inspect}")
-      end
-    end
-
-    def error_response(text)
-      self.response("451 #{text}")
-    end
-
-    def response(text)
-      @socket.puts(text) unless @socket.closed?
-    end
-
-    def stop
-      @datasocket.close unless @datasocket.nil? || @datasocket.closed?
-      @server.close
-      @thread.join
-    end
-
-
-    ##
-    def handle(sym, &block)
-      @handlers[sym] = block
-    end
-
-    def should_receive(method)
-      @handler_for = method
-      self
-    end
-
-    def and_respond(text)
-      @handlers[@handler_for] = -> s, *args { s.response(text) }
-    end
-
-    ##
-    # FTP methods
-    ##
-
-    def abor
-      self.response("226 Closing data connection. (ABOR)")
-    end
-
-    def acct(account)
-      @login_acct = account
-      self.response("230 User '#{account}' logged in, proceed. (ACCT)")
-    end
-
-    def cdup
-      self.response("200 Command okay. (CDUP)")
-    end
-
-    def cwd(dir)
-      self.response("200 Command okay. (CWD #{dir})")
-    end
-
-    def dele(file)
-      self.response("250 Requested file action okay, completed. (DELE #{file})")
-    end
-
-    def eprt(arg)
-      _, _, host, port = arg.split("|")
-
-      @datasocket = TCPSocket.new(host, port)
-      self.response("200 port opened")
-    end
-
-    def help(param = :default)
-      if param == :default
-        self.response("211 System status, or system help reply. (HELP)")
-      else
-        self.response("211 System status, or system help reply. (HELP #{param})")
-      end
-    end
-
-    def list(folder)
-      self.response("150 opening ASCII connection for file list")
-      @datasocket.puts("-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb")
-      @datasocket.puts("-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb")
-      @datasocket.puts("-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb")
-      @datasocket.close()
-      self.response("226 transfer complete (LIST #{folder})")
-    end
-
-    def mdtm(filename)
-      self.response("213 19980705132316")
-    end
-
-    def mkd(foldername)
-      self.response(%Q{257 "#{foldername.gsub('"', '""')}" created.})
-    end
-
-    def nlst(folder = nil)
-      self.response("150 opening ASCII connection for file list")
-      @datasocket.puts("last_response_code.rb")
-      @datasocket.puts("list.rb")
-      @datasocket.puts("pwd.rb")
-      @datasocket.close()
-      self.response("226 transfer complete (NLST#{folder ? " #{folder}" : ""})")
-    end
-
-    def noop
-      self.response("200 Command okay. (NOOP)")
-    end
-
-    def pass(password)
-      @login_pass = password
-      self.response("230 User logged in, proceed. (PASS #{password})")
-    end
-
-    def port(arg)
-      nums = arg.split(",")
-
-      if nums[0] == "::1"
-        # IPv6
-        port = nums[1].to_i * 256 + nums[2].to_i
-        host = nums[0]
-      else
-        # IPv4
-        port = nums[4].to_i * 256 + nums[5].to_i
-        host = nums[0..3].join(".")
-      end
-
-      @datasocket = TCPSocket.new(host, port)
-      self.response("200 port opened")
-    end
-
-    def pwd
-      self.response('257 "/some/dir/" - current directory')
-    end
-
-    def retr(file)
-      self.response("125 Data transfer starting")
-      if @restart_at && @restart_at == 20
-        @datasocket.puts("of the file named '#{file}'.")
-        @restart_at = nil
-      else
-        @datasocket.puts("This is the content")
-        @datasocket.puts("of the file named '#{file}'.")
-      end
-      @datasocket.close()
-      self.response("226 Closing data connection. (RETR #{file})")
-    end
-
-    def rest(at_bytes)
-      @restart_at = at_bytes.to_i
-      self.response("350 Requested file action pending further information. (REST)")
-    end
-
-    def rmd(folder)
-      self.response("250 Requested file action okay, completed. (RMD #{folder})")
-    end
-
-    def rnfr(from)
-      @rename_from = from
-      self.response("350 Requested file action pending further information.")
-    end
-
-    def rnto(to)
-      self.response("250 Requested file action okay, completed. (Renamed #{@rename_from} to #{to})")
-      @rename_from = nil
-    end
-
-    def site(param)
-      self.response("200 Command okay. (SITE #{param})")
-    end
-
-    def size(filename)
-      if filename == "binary"
-        self.response("213 24")
-      else
-        self.response("213 1024")
-      end
-    end
-
-    def stat(param = :default)
-      if param == :default
-        self.response("211 System status, or system help reply. (STAT)")
-      else
-        self.response("211 System status, or system help reply. (STAT #{param})")
-      end
-    end
-
-    def stor(file)
-      tmp_file = tmp("#{file}file", false)
-
-      self.response("125 Data transfer starting.")
-
-      mode = @restart_at ? "a" : "w"
-
-      File.open(tmp_file, mode + "b") do |f|
-        loop do
-          data = @datasocket.recv(1024)
-          break if !data || data.empty?
-          f << data
-        end
-      end
-
-      #@datasocket.close()
-      self.response("200 OK, Data received. (STOR #{file})")
-    end
-
-    def appe(file)
-      @restart_at = true
-      stor(file)
-    end
-
-    def syst
-      self.response("215 FTP Dummy Server (SYST)")
-    end
-
-    def type(type)
-      self.response("200 TYPE switched to #{type}")
-    end
-
-    def user(name)
-      @login_user = name
-      self.response("230 User logged in, proceed. (USER #{name})")
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/get_spec.rb b/spec/ruby/library/net/ftp/get_spec.rb
deleted file mode 100644
index c4672b55a5..0000000000
--- a/spec/ruby/library/net/ftp/get_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/gettextfile'
-require_relative 'shared/getbinaryfile'
-
-describe "Net::FTP#get (binary mode)" do
-  before :each do
-    @binary_mode = true
-  end
-
-  it_behaves_like :net_ftp_getbinaryfile, :get
-end
-
-describe "Net::FTP#get (text mode)" do
-  before :each do
-    @binary_mode = false
-  end
-
-  it_behaves_like :net_ftp_gettextfile, :get
-end
diff --git a/spec/ruby/library/net/ftp/getbinaryfile_spec.rb b/spec/ruby/library/net/ftp/getbinaryfile_spec.rb
deleted file mode 100644
index 155851b53c..0000000000
--- a/spec/ruby/library/net/ftp/getbinaryfile_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/getbinaryfile'
-
-describe "Net::FTP#getbinaryfile" do
-  it_behaves_like :net_ftp_getbinaryfile, :getbinaryfile
-end
diff --git a/spec/ruby/library/net/ftp/getdir_spec.rb b/spec/ruby/library/net/ftp/getdir_spec.rb
deleted file mode 100644
index eea35ac130..0000000000
--- a/spec/ruby/library/net/ftp/getdir_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'shared/pwd'
-
-describe "Net::FTP#getdir" do
-  it_behaves_like :net_ftp_pwd, :getdir
-end
diff --git a/spec/ruby/library/net/ftp/gettextfile_spec.rb b/spec/ruby/library/net/ftp/gettextfile_spec.rb
deleted file mode 100644
index 79395ae009..0000000000
--- a/spec/ruby/library/net/ftp/gettextfile_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/gettextfile'
-
-describe "Net::FTP#gettextfile" do
-  it_behaves_like :net_ftp_gettextfile, :gettextfile
-end
diff --git a/spec/ruby/library/net/ftp/help_spec.rb b/spec/ruby/library/net/ftp/help_spec.rb
deleted file mode 100644
index d2e9fe7ee8..0000000000
--- a/spec/ruby/library/net/ftp/help_spec.rb
+++ /dev/null
@@ -1,66 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#help" do
-  def with_connection
-    yield
-  end
-
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "writes the HELP command to the server" do
-    @ftp.help
-    @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
-  end
-
-  it "returns the server's response" do
-    @ftp.help.should == "211 System status, or system help reply. (HELP)\n"
-  end
-
-  it "writes the HELP command with an optional parameter to the socket" do
-    @ftp.help("some parameter").should == "211 System status, or system help reply. (HELP some parameter)\n"
-  end
-
-  it "does not raise any error when the response code is 211" do
-    @server.should_receive(:help).and_respond("211 System status, or system help reply.")
-    -> { @ftp.help }.should_not raise_error
-  end
-
-  it "does not raise any error when the response code is 214" do
-    @server.should_receive(:help).and_respond("214 Help message.")
-    -> { @ftp.help }.should_not raise_error
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:help).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.help }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:help).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.help }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:help).and_respond("502 Command not implemented.")
-    -> { @ftp.help }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:help).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.help }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/initialize_spec.rb b/spec/ruby/library/net/ftp/initialize_spec.rb
deleted file mode 100644
index 507320e494..0000000000
--- a/spec/ruby/library/net/ftp/initialize_spec.rb
+++ /dev/null
@@ -1,407 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#initialize" do
-  before :each do
-    @ftp = Net::FTP.allocate
-    @ftp.stub!(:connect)
-    @port_args = []
-    ruby_version_is "2.5" do
-      @port_args << 21
-    end
-  end
-
-  it "is private" do
-    Net::FTP.should have_private_instance_method(:initialize)
-  end
-
-  it "sets self into binary mode" do
-    @ftp.binary.should be_nil
-    @ftp.send(:initialize)
-    @ftp.binary.should be_true
-  end
-
-  it "sets self into active mode" do
-    @ftp.passive.should be_nil
-    @ftp.send(:initialize)
-    @ftp.passive.should be_false
-  end
-
-  it "sets self into non-debug mode" do
-    @ftp.debug_mode.should be_nil
-    @ftp.send(:initialize)
-    @ftp.debug_mode.should be_false
-  end
-
-  it "sets self to not resume file uploads/downloads" do
-    @ftp.resume.should be_nil
-    @ftp.send(:initialize)
-    @ftp.resume.should be_false
-  end
-
-  describe "when passed no arguments" do
-    it "does not try to connect" do
-      @ftp.should_not_receive(:connect)
-      @ftp.send(:initialize)
-    end
-  end
-
-  describe "when passed host" do
-    it "tries to connect to the passed host" do
-      @ftp.should_receive(:connect).with("localhost", *@port_args)
-      @ftp.send(:initialize, "localhost")
-    end
-  end
-
-  describe "when passed host, user" do
-    it "tries to connect to the passed host" do
-      @ftp.should_receive(:connect).with("localhost", *@port_args)
-      @ftp.send(:initialize, "localhost")
-    end
-
-    it "tries to login with the passed username" do
-      @ftp.should_receive(:login).with("rubyspec", nil, nil)
-      @ftp.send(:initialize, "localhost", "rubyspec")
-    end
-  end
-
-  describe "when passed host, user, password" do
-    it "tries to connect to the passed host" do
-      @ftp.should_receive(:connect).with("localhost", *@port_args)
-      @ftp.send(:initialize, "localhost")
-    end
-
-    it "tries to login with the passed username and password" do
-      @ftp.should_receive(:login).with("rubyspec", "rocks", nil)
-      @ftp.send(:initialize, "localhost", "rubyspec", "rocks")
-    end
-  end
-
-  describe "when passed host, user" do
-    it "tries to connect to the passed host" do
-      @ftp.should_receive(:connect).with("localhost", *@port_args)
-      @ftp.send(:initialize, "localhost")
-    end
-
-    it "tries to login with the passed username, password and account" do
-      @ftp.should_receive(:login).with("rubyspec", "rocks", "account")
-      @ftp.send(:initialize, "localhost", "rubyspec", "rocks", "account")
-    end
-  end
-
-  before :each do
-    @ftp.stub!(:login)
-  end
-
-  describe 'when the host' do
-    describe 'is set' do
-      describe 'and port option' do
-        describe 'is set' do
-          it 'tries to connect to the host on the specified port' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({ port: 8080 })
-            @ftp.should_receive(:connect).with('localhost', 8080)
-
-            @ftp.send(:initialize, 'localhost', options)
-          end
-        end
-
-        describe 'is not set' do
-          it 'tries to connect to the host without a port' do
-            @ftp.should_receive(:connect).with("localhost", *@port_args)
-
-            @ftp.send(:initialize, 'localhost')
-          end
-        end
-      end
-
-      describe 'when the username option' do
-        describe 'is set' do
-          describe 'and the password option' do
-            describe 'is set' do
-              describe 'and the account option' do
-                describe 'is set' do
-                  it 'tries to log in with the supplied parameters' do
-                    options = mock('ftp initialize options')
-                    options.should_receive(:to_hash).and_return({ username: 'a', password: 'topsecret', account: 'b' })
-                    @ftp.should_receive(:login).with('a', 'topsecret', 'b')
-
-                    @ftp.send(:initialize, 'localhost', options)
-                  end
-                end
-
-                describe 'is unset' do
-                  it 'tries to log in with the supplied parameters' do
-                    options = mock('ftp initialize options')
-                    options.should_receive(:to_hash).and_return({ username: 'a', password: 'topsecret' })
-                    @ftp.should_receive(:login).with('a', 'topsecret', nil)
-
-                    @ftp.send(:initialize, 'localhost', options)
-                  end
-                end
-              end
-            end
-
-            describe 'is unset' do
-              describe 'and the account option' do
-                describe 'is set' do
-                  it 'tries to log in with the supplied parameters' do
-                    options = mock('ftp initialize options')
-                    options.should_receive(:to_hash).and_return({ username: 'a', account: 'b' })
-                    @ftp.should_receive(:login).with('a', nil, 'b')
-
-                    @ftp.send(:initialize, 'localhost', options)
-                  end
-                end
-
-                describe 'is unset' do
-                  it 'tries to log in with the supplied parameters' do
-                    options = mock('ftp initialize options')
-                    options.should_receive(:to_hash).and_return({ username: 'a'})
-                    @ftp.should_receive(:login).with('a', nil, nil)
-
-                    @ftp.send(:initialize, 'localhost', options)
-                  end
-                end
-              end
-            end
-          end
-        end
-
-        describe 'is not set' do
-          it 'does not try to log in' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({})
-            @ftp.should_not_receive(:login)
-
-            @ftp.send(:initialize, 'localhost', options)
-          end
-        end
-      end
-    end
-
-    describe 'is unset' do
-      it 'does not try to connect' do
-        @ftp.should_not_receive(:connect)
-
-        @ftp.send(:initialize)
-      end
-
-      it 'does not try to log in' do
-        @ftp.should_not_receive(:login)
-
-        @ftp.send(:initialize)
-      end
-    end
-  end
-
-  describe 'when the passive option' do
-    describe 'is set' do
-      describe 'to true' do
-        it 'sets passive to true' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ passive: true })
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.passive.should == true
-        end
-      end
-
-      describe 'to false' do
-        it 'sets passive to false' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ passive: false })
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.passive.should == false
-        end
-      end
-    end
-
-    describe 'is unset' do
-      it 'sets passive to false' do
-        @ftp.send(:initialize)
-        @ftp.passive.should == false
-      end
-    end
-  end
-
-  describe 'when the debug_mode option' do
-    describe 'is set' do
-      describe 'to true' do
-        it 'sets debug_mode to true' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ debug_mode: true })
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.debug_mode.should == true
-        end
-      end
-
-      describe 'to false' do
-        it 'sets debug_mode to false' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ debug_mode: false })
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.debug_mode.should == false
-        end
-      end
-    end
-
-    describe 'is unset' do
-      it 'sets debug_mode to false' do
-        @ftp.send(:initialize)
-        @ftp.debug_mode.should == false
-      end
-    end
-  end
-
-  describe 'when the open_timeout option' do
-    describe 'is set' do
-      it 'sets open_timeout to the specified value' do
-        options = mock('ftp initialize options')
-        options.should_receive(:to_hash).and_return({ open_timeout: 42 })
-
-        @ftp.send(:initialize, nil, options)
-        @ftp.open_timeout.should == 42
-      end
-    end
-
-    describe 'is not set' do
-      it 'sets open_timeout to nil' do
-        @ftp.send(:initialize)
-        @ftp.open_timeout.should == nil
-      end
-    end
-  end
-
-  describe 'when the read_timeout option' do
-    describe 'is set' do
-      it 'sets read_timeout to the specified value' do
-        options = mock('ftp initialize options')
-        options.should_receive(:to_hash).and_return({ read_timeout: 100 })
-
-        @ftp.send(:initialize, nil, options)
-        @ftp.read_timeout.should == 100
-      end
-    end
-
-    describe 'is not set' do
-      it 'sets read_timeout to the default value' do
-        @ftp.send(:initialize)
-        @ftp.read_timeout.should == 60
-      end
-    end
-  end
-
-  describe 'when the ssl_handshake_timeout option' do
-    describe 'is set' do
-      it 'sets ssl_handshake_timeout to the specified value' do
-        options = mock('ftp initialize options')
-        options.should_receive(:to_hash).and_return({ ssl_handshake_timeout: 23 })
-
-        @ftp.send(:initialize, nil, options)
-        @ftp.ssl_handshake_timeout.should == 23
-      end
-    end
-
-    describe 'is not set' do
-      it 'sets ssl_handshake_timeout to nil' do
-        @ftp.send(:initialize)
-        @ftp.ssl_handshake_timeout.should == nil
-      end
-    end
-  end
-
-  describe 'when the ssl option' do
-    describe 'is set' do
-      describe "and the ssl option's value is true" do
-        it 'initializes ssl_context to a blank SSLContext object' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ ssl: true })
-
-          ssl_context = OpenSSL::SSL::SSLContext.allocate
-          ssl_context.stub!(:set_params)
-
-          OpenSSL::SSL::SSLContext.should_receive(:new).and_return(ssl_context)
-          ssl_context.should_receive(:set_params).with({})
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.instance_variable_get(:@ssl_context).should == ssl_context
-        end
-      end
-
-      describe "and the ssl option's value is a hash" do
-        it 'initializes ssl_context to a configured SSLContext object' do
-          options = mock('ftp initialize options')
-          options.should_receive(:to_hash).and_return({ ssl: {key: 'value'} })
-
-          ssl_context = OpenSSL::SSL::SSLContext.allocate
-          ssl_context.stub!(:set_params)
-
-          OpenSSL::SSL::SSLContext.should_receive(:new).and_return(ssl_context)
-          ssl_context.should_receive(:set_params).with({key: 'value'})
-
-          @ftp.send(:initialize, nil, options)
-          @ftp.instance_variable_get(:@ssl_context).should == ssl_context
-        end
-      end
-
-      describe 'and private_data_connection' do
-        describe 'is set' do
-          it 'sets private_data_connection to that value' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({ ssl: true, private_data_connection: 'true' })
-
-            @ftp.send(:initialize, nil, options)
-            @ftp.instance_variable_get(:@private_data_connection).should == 'true'
-          end
-        end
-
-        describe 'is not set' do
-          it 'sets private_data_connection to nil' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({ ssl: true })
-
-            @ftp.send(:initialize, nil, options)
-            @ftp.instance_variable_get(:@private_data_connection).should == true
-          end
-        end
-      end
-    end
-
-    describe 'is not set' do
-      it 'sets ssl_context to nil' do
-        options = mock('ftp initialize options')
-        options.should_receive(:to_hash).and_return({})
-
-        @ftp.send(:initialize, nil, options)
-        @ftp.instance_variable_get(:@ssl_context).should == nil
-      end
-
-      describe 'private_data_connection' do
-        describe 'is set' do
-          it 'raises an ArgumentError' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({ private_data_connection: true })
-
-            -> {
-              @ftp.send(:initialize, nil, options)
-            }.should raise_error(ArgumentError, /private_data_connection can be set to true only when ssl is enabled/)
-          end
-        end
-
-        describe 'is not set' do
-          it 'sets private_data_connection to false' do
-            options = mock('ftp initialize options')
-            options.should_receive(:to_hash).and_return({})
-
-            @ftp.send(:initialize, nil, options)
-            @ftp.instance_variable_get(:@private_data_connection).should == false
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/last_response_code_spec.rb b/spec/ruby/library/net/ftp/last_response_code_spec.rb
deleted file mode 100644
index 3eb20f7ad8..0000000000
--- a/spec/ruby/library/net/ftp/last_response_code_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'shared/last_response_code'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#last_response_code" do
-  it_behaves_like :net_ftp_last_response_code, :last_response_code
-end
diff --git a/spec/ruby/library/net/ftp/last_response_spec.rb b/spec/ruby/library/net/ftp/last_response_spec.rb
deleted file mode 100644
index ada665d59c..0000000000
--- a/spec/ruby/library/net/ftp/last_response_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#last_response" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "returns the last response" do
-    @ftp.last_response.should == "220 Dummy FTP Server ready!\n"
-    @ftp.help
-    @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
-  end
-end
diff --git a/spec/ruby/library/net/ftp/lastresp_spec.rb b/spec/ruby/library/net/ftp/lastresp_spec.rb
deleted file mode 100644
index 273e216e8b..0000000000
--- a/spec/ruby/library/net/ftp/lastresp_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'shared/last_response_code'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#lastresp" do
-  it_behaves_like :net_ftp_last_response_code, :lastresp
-end
diff --git a/spec/ruby/library/net/ftp/list_spec.rb b/spec/ruby/library/net/ftp/list_spec.rb
deleted file mode 100644
index 6175172923..0000000000
--- a/spec/ruby/library/net/ftp/list_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/list'
-
-describe "Net::FTP#list" do
-  it_behaves_like :net_ftp_list, :list
-end
diff --git a/spec/ruby/library/net/ftp/login_spec.rb b/spec/ruby/library/net/ftp/login_spec.rb
deleted file mode 100644
index 46736851ee..0000000000
--- a/spec/ruby/library/net/ftp/login_spec.rb
+++ /dev/null
@@ -1,195 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#login" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  describe "when passed no arguments" do
-    it "sends the USER command with 'anonymous' as name to the server" do
-      @ftp.login
-      @server.login_user.should == "anonymous"
-    end
-
-    it "sends 'anonymous@' as a password when required" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @ftp.login
-      @server.login_pass.should == "anonymous@"
-    end
-
-    it "raises a Net::FTPReplyError when the server requests an account" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @server.should_receive(:pass).and_respond("332 Need account for login.")
-      -> { @ftp.login }.should raise_error(Net::FTPReplyError)
-    end
-  end
-
-  describe "when passed name" do
-    it "sends the USER command with the passed name to the server" do
-      @ftp.login("rubyspec")
-      @server.login_user.should == "rubyspec"
-    end
-
-    it "raises a Net::FTPReplyError when the server requests a password, but none was given" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      -> { @ftp.login("rubyspec") }.should raise_error(Net::FTPReplyError)
-    end
-
-    it "raises a Net::FTPReplyError when the server requests an account, but none was given" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @server.should_receive(:pass).and_respond("332 Need account for login.")
-      -> { @ftp.login("rubyspec") }.should raise_error(Net::FTPReplyError)
-    end
-  end
-
-  describe "when passed name, password" do
-    it "sends the USER command with the passed name to the server" do
-      @ftp.login("rubyspec", "rocks")
-      @server.login_user.should == "rubyspec"
-    end
-
-    it "sends the passed password when required" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @ftp.login("rubyspec", "rocks")
-      @server.login_pass.should == "rocks"
-    end
-
-    it "raises a Net::FTPReplyError when the server requests an account" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @server.should_receive(:pass).and_respond("332 Need account for login.")
-      -> { @ftp.login("rubyspec", "rocks") }.should raise_error(Net::FTPReplyError)
-    end
-  end
-
-  describe "when passed name, password, account" do
-    it "sends the USER command with the passed name to the server" do
-      @ftp.login("rubyspec", "rocks", "account")
-      @server.login_user.should == "rubyspec"
-    end
-
-    it "sends the passed password when required" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @ftp.login("rubyspec", "rocks", "account")
-      @server.login_pass.should == "rocks"
-    end
-
-    it "sends the passed account when required" do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @server.should_receive(:pass).and_respond("332 Need account for login.")
-      @ftp.login("rubyspec", "rocks", "account")
-      @server.login_acct.should == "account"
-    end
-  end
-
-  describe "when the USER command fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:user).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:user).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:user).and_respond("502 Command not implemented.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:user).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:user).and_respond("530 Not logged in.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when the PASS command fails" do
-    before :each do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-    end
-
-    it "does not raise an Error when the response code is 202" do
-      @server.should_receive(:pass).and_respond("202 Command not implemented, superfluous at this site.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should_not raise_error
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:pass).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:pass).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:pass).and_respond("502 Command not implemented.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:pass).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:pass).and_respond("530 Not logged in.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when the ACCT command fails" do
-    before :each do
-      @server.should_receive(:user).and_respond("331 User name okay, need password.")
-      @server.should_receive(:pass).and_respond("332 Need account for login.")
-    end
-
-    it "does not raise an Error when the response code is 202" do
-      @server.should_receive(:acct).and_respond("202 Command not implemented, superfluous at this site.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should_not raise_error
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:acct).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:acct).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:acct).and_respond("502 Command not implemented.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:acct).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:acct).and_respond("530 Not logged in.")
-      -> { @ftp.login("rubyspec", "rocks", "account") }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/ls_spec.rb b/spec/ruby/library/net/ftp/ls_spec.rb
deleted file mode 100644
index e729eb9481..0000000000
--- a/spec/ruby/library/net/ftp/ls_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/list'
-
-describe "Net::FTP#ls" do
-  it_behaves_like :net_ftp_list, :ls
-end
diff --git a/spec/ruby/library/net/ftp/mdtm_spec.rb b/spec/ruby/library/net/ftp/mdtm_spec.rb
deleted file mode 100644
index b74cf8d3c7..0000000000
--- a/spec/ruby/library/net/ftp/mdtm_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#mdtm" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the MDTM with the passed filename command to the server" do
-    @ftp.mdtm("test.file")
-    @ftp.last_response.should == "213 19980705132316\n"
-  end
-
-  it "returns the last modification time of the passed file" do
-    @ftp.mdtm("test.file").should == "19980705132316"
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:mdtm).and_respond("550 Requested action not taken.")
-    -> { @ftp.mdtm("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:mdtm).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.mdtm("test.file") }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/mkdir_spec.rb b/spec/ruby/library/net/ftp/mkdir_spec.rb
deleted file mode 100644
index 7dc45b5711..0000000000
--- a/spec/ruby/library/net/ftp/mkdir_spec.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#mkdir" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the MKD command with the passed pathname to the server" do
-    @ftp.mkdir("test.folder")
-    @ftp.last_response.should == %{257 "test.folder" created.\n}
-  end
-
-  it "returns the path to the newly created directory" do
-    @ftp.mkdir("test.folder").should == "test.folder"
-    @ftp.mkdir("/absolute/path/to/test.folder").should == "/absolute/path/to/test.folder"
-    @ftp.mkdir("relative/path/to/test.folder").should == "relative/path/to/test.folder"
-    @ftp.mkdir('/usr/dm/foo"bar').should == '/usr/dm/foo"bar'
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:mkd).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:mkd).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:mkd).and_respond("502 Command not implemented.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:mkd).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:mkd).and_respond("530 Not logged in.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:mkd).and_respond("550 Requested action not taken.")
-    -> { @ftp.mkdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/mtime_spec.rb b/spec/ruby/library/net/ftp/mtime_spec.rb
deleted file mode 100644
index 0f6cc1ba20..0000000000
--- a/spec/ruby/library/net/ftp/mtime_spec.rb
+++ /dev/null
@@ -1,50 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#mtime" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the MDTM with the passed filename command to the server" do
-    @ftp.mtime("test.file")
-    @ftp.last_response.should == "213 19980705132316\n"
-  end
-
-  describe "when passed filename" do
-    it "returns the last modification time of the passed file as a Time object in the local time" do
-      @ftp.mtime("test.file").should == Time.gm("1998", "07", "05", "13", "23", "16")
-    end
-  end
-
-  describe "when passed filename, local_time" do
-    it "returns the last modification time as a Time object in UTC when local_time is true" do
-      @ftp.mtime("test.file", true).should == Time.local("1998", "07", "05", "13", "23", "16")
-    end
-
-    it "returns the last modification time as a Time object in the local time when local_time is false" do
-      @ftp.mtime("test.file", false).should == Time.gm("1998", "07", "05", "13", "23", "16")
-    end
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:mdtm).and_respond("550 Requested action not taken.")
-    -> { @ftp.mtime("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:mdtm).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.mtime("test.file") }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/nlst_spec.rb b/spec/ruby/library/net/ftp/nlst_spec.rb
deleted file mode 100644
index 34384fb8c4..0000000000
--- a/spec/ruby/library/net/ftp/nlst_spec.rb
+++ /dev/null
@@ -1,92 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#nlst" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.passive = false
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  describe "when passed no arguments" do
-    it "returns an Array containing a list of files in the current dir" do
-      @ftp.nlst.should == ["last_response_code.rb", "list.rb", "pwd.rb"]
-      @ftp.last_response.should == "226 transfer complete (NLST)\n"
-    end
-  end
-
-  describe "when passed dir" do
-    it "returns an Array containing a list of files in the passed dir" do
-      @ftp.nlst("test.folder").should == ["last_response_code.rb", "list.rb", "pwd.rb"]
-      @ftp.last_response.should == "226 transfer complete (NLST test.folder)\n"
-    end
-  end
-
-  describe "when the NLST command fails" do
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:nlst).and_respond("450 Requested file action not taken..")
-      -> { @ftp.nlst }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:nlst).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:nlst).and_respond("501 Syntax error, command unrecognized.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:nlst).and_respond("502 Command not implemented.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:nlst).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:nlst).and_respond("530 Not logged in.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.nlst }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/noop_spec.rb b/spec/ruby/library/net/ftp/noop_spec.rb
deleted file mode 100644
index 070750ced7..0000000000
--- a/spec/ruby/library/net/ftp/noop_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#noop" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the NOOP command to the server" do
-    @ftp.noop
-    @ftp.last_response.should == "200 Command okay. (NOOP)\n"
-  end
-
-  it "returns nil" do
-    @ftp.noop.should be_nil
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:noop).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.noop }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:noop).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.noop }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/open_spec.rb b/spec/ruby/library/net/ftp/open_spec.rb
deleted file mode 100644
index 7be02ff373..0000000000
--- a/spec/ruby/library/net/ftp/open_spec.rb
+++ /dev/null
@@ -1,55 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP.open" do
-  before :each do
-    @ftp = mock("Net::FTP instance")
-    Net::FTP.stub!(:new).and_return(@ftp)
-  end
-
-  describe "when passed no block" do
-    it "returns a new Net::FTP instance" do
-      Net::FTP.open("localhost").should equal(@ftp)
-    end
-
-    it "passes the passed arguments down to Net::FTP.new" do
-      Net::FTP.should_receive(:new).with("localhost", "user", "password", "account")
-      Net::FTP.open("localhost", "user", "password", "account")
-    end
-  end
-
-  describe "when passed a block" do
-    before :each do
-      @ftp.stub!(:close)
-    end
-
-    it "yields a new Net::FTP instance to the passed block" do
-      yielded = false
-      Net::FTP.open("localhost") do |ftp|
-        yielded = true
-        ftp.should equal(@ftp)
-      end
-      yielded.should be_true
-    end
-
-    it "closes the Net::FTP instance after yielding" do
-      Net::FTP.open("localhost") do |ftp|
-        ftp.should_receive(:close)
-      end
-    end
-
-    it "closes the Net::FTP instance even if an exception is raised while yielding" do
-      begin
-        Net::FTP.open("localhost") do |ftp|
-          ftp.should_receive(:close)
-          raise ArgumentError, "some exception"
-        end
-      rescue ArgumentError
-      end
-    end
-
-    it "returns the block's return value" do
-      Net::FTP.open("localhost") { :test }.should == :test
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/passive_spec.rb b/spec/ruby/library/net/ftp/passive_spec.rb
deleted file mode 100644
index e8db030cbd..0000000000
--- a/spec/ruby/library/net/ftp/passive_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#passive" do
-  it "returns true when self is in passive mode" do
-    ftp = Net::FTP.new
-    ftp.passive.should be_false
-
-    ftp.passive = true
-    ftp.passive.should be_true
-  end
-
-  it "is the value of Net::FTP.default_value by default" do
-    ruby_exe(fixture(__FILE__, "passive.rb")).should == "true"
-  end
-end
-
-describe "Net::FTP#passive=" do
-  it "sets self to passive mode when passed true" do
-    ftp = Net::FTP.new
-
-    ftp.passive = true
-    ftp.passive.should be_true
-
-    ftp.passive = false
-    ftp.passive.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/ftp/put_spec.rb b/spec/ruby/library/net/ftp/put_spec.rb
deleted file mode 100644
index f1f85b5d05..0000000000
--- a/spec/ruby/library/net/ftp/put_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/puttextfile'
-require_relative 'shared/putbinaryfile'
-
-describe "Net::FTP#put (binary mode)" do
-  before :each do
-    @binary_mode = true
-  end
-
-  it_behaves_like :net_ftp_putbinaryfile, :put
-end
-
-describe "Net::FTP#put (text mode)" do
-  before :each do
-    @binary_mode = false
-  end
-
-  it_behaves_like :net_ftp_puttextfile, :put
-end
diff --git a/spec/ruby/library/net/ftp/putbinaryfile_spec.rb b/spec/ruby/library/net/ftp/putbinaryfile_spec.rb
deleted file mode 100644
index cb1c7bef5a..0000000000
--- a/spec/ruby/library/net/ftp/putbinaryfile_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/putbinaryfile'
-
-describe "Net::FTP#putbinaryfile" do
-  it_behaves_like :net_ftp_putbinaryfile, :putbinaryfile
-end
diff --git a/spec/ruby/library/net/ftp/puttextfile_spec.rb b/spec/ruby/library/net/ftp/puttextfile_spec.rb
deleted file mode 100644
index 00a930afd7..0000000000
--- a/spec/ruby/library/net/ftp/puttextfile_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-require_relative 'shared/puttextfile'
-
-describe "Net::FTP#puttextfile" do
-  it_behaves_like :net_ftp_puttextfile, :puttextfile
-end
diff --git a/spec/ruby/library/net/ftp/pwd_spec.rb b/spec/ruby/library/net/ftp/pwd_spec.rb
deleted file mode 100644
index a3998cc730..0000000000
--- a/spec/ruby/library/net/ftp/pwd_spec.rb
+++ /dev/null
@@ -1,53 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#pwd" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the PWD command to the server" do
-    @ftp.pwd
-    @ftp.last_response.should == "257 \"/some/dir/\" - current directory\n"
-  end
-
-  it "returns the current directory" do
-    @ftp.pwd.should == "/some/dir/"
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:pwd).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.pwd }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:pwd).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.pwd }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:pwd).and_respond("502 Command not implemented.")
-    -> { @ftp.pwd }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:pwd).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.pwd }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:pwd).and_respond("550 Requested action not taken.")
-    -> { @ftp.pwd }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/quit_spec.rb b/spec/ruby/library/net/ftp/quit_spec.rb
deleted file mode 100644
index 8e3cb28b90..0000000000
--- a/spec/ruby/library/net/ftp/quit_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#quit" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the QUIT command to the server" do
-    @ftp.quit
-    @ftp.last_response.should == "221 OK, bye\n"
-  end
-
-  it "does not close the socket automatically" do
-    @ftp.quit
-    @ftp.closed?.should be_false
-  end
-
-  it "returns nil" do
-    @ftp.quit.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/ftp/rename_spec.rb b/spec/ruby/library/net/ftp/rename_spec.rb
deleted file mode 100644
index 376b203ac9..0000000000
--- a/spec/ruby/library/net/ftp/rename_spec.rb
+++ /dev/null
@@ -1,94 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#rename" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  describe "when passed from_name, to_name" do
-    it "sends the RNFR command with the passed from_name and the RNTO command with the passed to_name to the server" do
-      @ftp.rename("from.file", "to.file")
-      @ftp.last_response.should == "250 Requested file action okay, completed. (Renamed from.file to to.file)\n"
-    end
-
-    it "returns something" do
-      @ftp.rename("from.file", "to.file").should be_nil
-    end
-  end
-
-  describe "when the RNFR command fails" do
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:rnfr).and_respond("450 Requested file action not taken.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 550" do
-      @server.should_receive(:rnfr).and_respond("550 Requested action not taken.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:rnfr).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:rnfr).and_respond("502 Command not implemented.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:rnfr).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:rnfr).and_respond("530 Not logged in.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when the RNTO command fails" do
-    it "raises a Net::FTPPermError when the response code is 532" do
-      @server.should_receive(:rnfr).and_respond("532 Need account for storing files.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 553" do
-      @server.should_receive(:rnto).and_respond("553 Requested action not taken.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:rnto).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:rnto).and_respond("502 Command not implemented.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:rnto).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:rnto).and_respond("530 Not logged in.")
-      -> { @ftp.rename("from.file", "to.file") }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/resume_spec.rb b/spec/ruby/library/net/ftp/resume_spec.rb
deleted file mode 100644
index 51b1cff2a4..0000000000
--- a/spec/ruby/library/net/ftp/resume_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#resume" do
-  it "returns true when self is set to resume uploads/downloads" do
-    ftp = Net::FTP.new
-    ftp.resume.should be_false
-
-    ftp.resume = true
-    ftp.resume.should be_true
-  end
-end
-
-describe "Net::FTP#resume=" do
-  it "sets self to resume uploads/downloads when set to true" do
-    ftp = Net::FTP.new
-    ftp.resume = true
-    ftp.resume.should be_true
-
-    ftp.resume = false
-    ftp.resume.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/ftp/retrbinary_spec.rb b/spec/ruby/library/net/ftp/retrbinary_spec.rb
deleted file mode 100644
index 30e2484af5..0000000000
--- a/spec/ruby/library/net/ftp/retrbinary_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#retrbinary" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the passed command to the server" do
-    @ftp.retrbinary("RETR test", 4096) {}
-    @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
-  end
-
-  it "yields the received content as binary blocks of the passed size" do
-    res = []
-    @ftp.retrbinary("RETR test", 10) { |bin| res << bin }
-    res.should == [ "This is th", "e content\n", "of the fil", "e named 't", "est'.\n" ]
-  end
-end
diff --git a/spec/ruby/library/net/ftp/retrlines_spec.rb b/spec/ruby/library/net/ftp/retrlines_spec.rb
deleted file mode 100644
index 546df3844e..0000000000
--- a/spec/ruby/library/net/ftp/retrlines_spec.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#retrlines" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the passed command over the socket" do
-    @ftp.retrlines("LIST test.dir") {}
-    @ftp.last_response.should == "226 transfer complete (LIST test.dir)\n"
-  end
-
-  it "yields each received line to the passed block" do
-    res = []
-    @ftp.retrlines("LIST test.dir") { |x| res << x }
-    res.should == [
-      "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
-      "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
-      "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
-    ]
-  end
-end
diff --git a/spec/ruby/library/net/ftp/return_code_spec.rb b/spec/ruby/library/net/ftp/return_code_spec.rb
deleted file mode 100644
index e4b98c8031..0000000000
--- a/spec/ruby/library/net/ftp/return_code_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#return_code" do
-  before :each do
-    @ftp = Net::FTP.new
-  end
-
-  it "outputs a warning and returns a newline" do
-    -> do
-      @ftp.return_code.should == "\n"
-    end.should complain(/warning: Net::FTP#return_code is obsolete and do nothing/)
-  end
-end
-
-describe "Net::FTP#return_code=" do
-  before :each do
-    @ftp = Net::FTP.new
-  end
-
-  it "outputs a warning" do
-    -> { @ftp.return_code = 123 }.should complain(/warning: Net::FTP#return_code= is obsolete and do nothing/)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/rmdir_spec.rb b/spec/ruby/library/net/ftp/rmdir_spec.rb
deleted file mode 100644
index 0515897998..0000000000
--- a/spec/ruby/library/net/ftp/rmdir_spec.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#rmdir" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the RMD command with the passed pathname to the server" do
-    @ftp.rmdir("test.folder")
-    @ftp.last_response.should == "250 Requested file action okay, completed. (RMD test.folder)\n"
-  end
-
-  it "returns nil" do
-    @ftp.rmdir("test.folder").should be_nil
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:rmd).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:rmd).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:rmd).and_respond("502 Command not implemented.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:rmd).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:rmd).and_respond("530 Not logged in.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:rmd).and_respond("550 Requested action not taken.")
-    -> { @ftp.rmdir("test.folder") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/sendcmd_spec.rb b/spec/ruby/library/net/ftp/sendcmd_spec.rb
deleted file mode 100644
index dafa36e032..0000000000
--- a/spec/ruby/library/net/ftp/sendcmd_spec.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#sendcmd" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the passed command to the server" do
-    @ftp.sendcmd("HELP")
-    @ftp.last_response.should == "211 System status, or system help reply. (HELP)\n"
-  end
-
-  it "returns the server's response" do
-    @ftp.sendcmd("HELP").should == "211 System status, or system help reply. (HELP)\n"
-  end
-
-  it "raises no error when the response code is 1xx, 2xx or 3xx" do
-    @server.should_receive(:help).and_respond("120 Service ready in nnn minutes.")
-    -> { @ftp.sendcmd("HELP") }.should_not raise_error
-
-    @server.should_receive(:help).and_respond("200 Command okay.")
-    -> { @ftp.sendcmd("HELP") }.should_not raise_error
-
-    @server.should_receive(:help).and_respond("350 Requested file action pending further information.")
-    -> { @ftp.sendcmd("HELP") }.should_not raise_error
-  end
-
-  it "raises a Net::FTPTempError when the response code is 4xx" do
-    @server.should_receive(:help).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.sendcmd("HELP") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 5xx" do
-    @server.should_receive(:help).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.sendcmd("HELP") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPProtoError when the response code is not between 1xx-5xx" do
-    @server.should_receive(:help).and_respond("999 Invalid response.")
-    -> { @ftp.sendcmd("HELP") }.should raise_error(Net::FTPProtoError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/set_socket_spec.rb b/spec/ruby/library/net/ftp/set_socket_spec.rb
deleted file mode 100644
index 7ca3bbbe27..0000000000
--- a/spec/ruby/library/net/ftp/set_socket_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-
-describe "Net::FTP#set_socket" do
-  # TODO: I won't spec this method, as it is not used
-  #       anywhere and it should be private anyway.
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/library/net/ftp/shared/getbinaryfile.rb b/spec/ruby/library/net/ftp/shared/getbinaryfile.rb
deleted file mode 100644
index f324f5b85d..0000000000
--- a/spec/ruby/library/net/ftp/shared/getbinaryfile.rb
+++ /dev/null
@@ -1,150 +0,0 @@
-describe :net_ftp_getbinaryfile, shared: :true do
-  before :each do
-    @fixture_file = File.dirname(__FILE__) + "/../fixtures/getbinaryfile"
-    @tmp_file = tmp("getbinaryfile")
-
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-    @ftp.binary = @binary_mode
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @tmp_file
-  end
-
-  it "sends the RETR command to the server" do
-    @ftp.send(@method, "test", @tmp_file)
-    @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
-  end
-
-  it "returns nil" do
-    @ftp.send(@method, "test", @tmp_file).should be_nil
-  end
-
-  it "saves the contents of the passed remote file to the passed local file" do
-    @ftp.send(@method, "test", @tmp_file)
-    File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
-  end
-
-  describe "when passed a block" do
-    it "yields the received content as binary blocks of the passed size" do
-      res = []
-      @ftp.send(@method, "test", @tmp_file, 10) { |bin| res << bin }
-      res.should == [ "This is th", "e content\n", "of the fil", "e named 't", "est'.\n" ]
-    end
-  end
-
-  describe "when resuming an existing file" do
-    before :each do
-      @tmp_file = tmp("getbinaryfile_resume")
-
-      File.open(@tmp_file, "wb") do |f|
-        f << "This is the content\n"
-      end
-
-      @ftp.resume = true
-    end
-
-    it "saves the remaining content of the passed remote file to the passed local file" do
-      @ftp.send(@method, "test", @tmp_file)
-      File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
-    end
-
-    describe "and the REST command fails" do
-      it "raises a Net::FTPProtoError when the response code is 550" do
-        @server.should_receive(:rest).and_respond("Requested action not taken.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPProtoError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 500" do
-        @server.should_receive(:rest).and_respond("500 Syntax error, command unrecognized.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 501" do
-        @server.should_receive(:rest).and_respond("501 Syntax error, command unrecognized.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 502" do
-        @server.should_receive(:rest).and_respond("502 Command not implemented.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPTempError when the response code is 421" do
-        @server.should_receive(:rest).and_respond("421 Service not available, closing control connection.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 530" do
-        @server.should_receive(:rest).and_respond("530 Not logged in.")
-        -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-      end
-    end
-  end
-
-  describe "when the RETR command fails" do
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:retr).and_respond("450 Requested file action not taken.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPProtoError when the response code is 550" do
-      @server.should_receive(:retr).and_respond("Requested action not taken.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPProtoError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:retr).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:retr).and_respond("501 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:retr).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:retr).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/gettextfile.rb b/spec/ruby/library/net/ftp/shared/gettextfile.rb
deleted file mode 100644
index 82bec2a4a7..0000000000
--- a/spec/ruby/library/net/ftp/shared/gettextfile.rb
+++ /dev/null
@@ -1,100 +0,0 @@
-describe :net_ftp_gettextfile, shared: :true do
-  before :each do
-    @tmp_file = tmp("gettextfile")
-
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-    @ftp.binary = @binary_mode
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @tmp_file
-  end
-
-  it "sends the RETR command to the server" do
-    @ftp.send(@method, "test", @tmp_file)
-    @ftp.last_response.should == "226 Closing data connection. (RETR test)\n"
-  end
-
-  it "returns nil" do
-    @ftp.send(@method, "test", @tmp_file).should be_nil
-  end
-
-  it "saves the contents of the passed remote file to the passed local file" do
-    @ftp.send(@method, "test", @tmp_file)
-    File.read(@tmp_file).should == "This is the content\nof the file named 'test'.\n"
-  end
-
-  describe "when passed a block" do
-    it "yields each line of the retrieved file to the passed block" do
-      res = []
-      @ftp.send(@method, "test", @tmp_file) { |line| res << line }
-      res.should == [ "This is the content", "of the file named 'test'."]
-    end
-  end
-
-  describe "when the RETR command fails" do
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:retr).and_respond("450 Requested file action not taken.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPProtoError when the response code is 550" do
-      @server.should_receive(:retr).and_respond("Requested action not taken.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPProtoError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:retr).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:retr).and_respond("501 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:retr).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:retr).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, "test", @tmp_file) }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/last_response_code.rb b/spec/ruby/library/net/ftp/shared/last_response_code.rb
deleted file mode 100644
index 4fe53677db..0000000000
--- a/spec/ruby/library/net/ftp/shared/last_response_code.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-describe :net_ftp_last_response_code, shared: true do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "returns the response code for the last response" do
-    @server.should_receive(:help).and_respond("200 Command okay.")
-    @ftp.help
-    @ftp.send(@method).should == "200"
-
-    @server.should_receive(:help).and_respond("212 Directory status.")
-    @ftp.help
-    @ftp.send(@method).should == "212"
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/list.rb b/spec/ruby/library/net/ftp/shared/list.rb
deleted file mode 100644
index adc3fa59c1..0000000000
--- a/spec/ruby/library/net/ftp/shared/list.rb
+++ /dev/null
@@ -1,104 +0,0 @@
-describe :net_ftp_list, shared: true do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.passive = false
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  describe "when passed a block" do
-    it "yields each file in the list of files in the passed dir" do
-      expected = [
-        "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
-        "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
-        "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
-      ]
-
-      res = []
-      @ftp.send(@method, "test.folder") { |line| res << line}
-      res.should == expected
-
-      @ftp.last_response.should == "226 transfer complete (LIST test.folder)\n"
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Array containing a list of files in the passed dir" do
-      expected = [
-        "-rw-r--r--  1 spec  staff  507 17 Jul 18:41 last_response_code.rb",
-        "-rw-r--r--  1 spec  staff   50 17 Jul 18:41 list.rb",
-        "-rw-r--r--  1 spec  staff   48 17 Jul 18:41 pwd.rb"
-      ]
-
-      @ftp.send(@method, "test.folder").should == expected
-
-      @ftp.last_response.should == "226 transfer complete (LIST test.folder)\n"
-    end
-  end
-
-  describe "when the LIST command fails" do
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:list).and_respond("450 Requested file action not taken..")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:list).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:list).and_respond("501 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 502" do
-      @server.should_receive(:list).and_respond("502 Command not implemented.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:list).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:list).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method) }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/putbinaryfile.rb b/spec/ruby/library/net/ftp/shared/putbinaryfile.rb
deleted file mode 100644
index 1163a1cfea..0000000000
--- a/spec/ruby/library/net/ftp/shared/putbinaryfile.rb
+++ /dev/null
@@ -1,167 +0,0 @@
-describe :net_ftp_putbinaryfile, shared: :true do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @local_fixture_file  = File.dirname(__FILE__) + "/../fixtures/putbinaryfile"
-    @remote_tmp_file = tmp("binaryfile", false)
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-    @ftp.binary = @binary_mode
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @remote_tmp_file
-  end
-
-  it "sends the STOR command to the server" do
-    @ftp.send(@method, @local_fixture_file, "binary")
-    @ftp.last_response.should == "200 OK, Data received. (STOR binary)\n"
-  end
-
-  it "sends the contents of the passed local_file, without modifications" do
-    @ftp.send(@method, @local_fixture_file, "binary")
-
-    remote_lines = File.readlines(@remote_tmp_file)
-    local_lines  = File.readlines(@local_fixture_file)
-
-    remote_lines.should == local_lines
-  end
-
-  it "returns nil" do
-    @ftp.send(@method, @local_fixture_file, "binary").should be_nil
-  end
-
-  describe "when passed a block" do
-    it "yields the transmitted content as binary blocks of the passed size" do
-      res = []
-      @ftp.send(@method, @local_fixture_file, "binary", 10) { |x| res << x }
-      res.should == [
-        "This is an", " example f",
-        "ile\nwhich ", "is going t",
-        "o be trans", "mitted\nusi",
-        "ng #putbin", "aryfile.\n"
-      ]
-    end
-  end
-
-  describe "when resuming an existing file" do
-    before :each do
-      File.open(@remote_tmp_file, "w") do |f|
-        f << "This is an example file\n"
-      end
-
-      @ftp.resume = true
-    end
-
-    it "sends the remaining content of the passed local_file to the passed remote_file" do
-      @ftp.send(@method, @local_fixture_file, "binary")
-      File.read(@remote_tmp_file).should == File.read(@local_fixture_file)
-    end
-
-    describe "and the APPE command fails" do
-      it "raises a Net::FTPProtoError when the response code is 550" do
-        @server.should_receive(:appe).and_respond("Requested action not taken.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPProtoError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 500" do
-        @server.should_receive(:appe).and_respond("500 Syntax error, command unrecognized.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 501" do
-        @server.should_receive(:appe).and_respond("501 Syntax error, command unrecognized.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 502" do
-        @server.should_receive(:appe).and_respond("502 Command not implemented.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-      end
-
-      it "raises a Net::FTPTempError when the response code is 421" do
-        @server.should_receive(:appe).and_respond("421 Service not available, closing control connection.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPTempError)
-      end
-
-      it "raises a Net::FTPPermError when the response code is 530" do
-        @server.should_receive(:appe).and_respond("530 Not logged in.")
-        -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-      end
-    end
-  end
-
-  describe "when the STOR command fails" do
-    it "raises a Net::FTPPermError when the response code is 532" do
-      @server.should_receive(:stor).and_respond("532 Need account for storing files.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:stor).and_respond("450 Requested file action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 452" do
-      @server.should_receive(:stor).and_respond("452 Requested action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 553" do
-      @server.should_receive(:stor).and_respond("553 Requested action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:stor).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:stor).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:stor).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:stor).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, @local_fixture_file, "binary") }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/puttextfile.rb b/spec/ruby/library/net/ftp/shared/puttextfile.rb
deleted file mode 100644
index 50e8de28e6..0000000000
--- a/spec/ruby/library/net/ftp/shared/puttextfile.rb
+++ /dev/null
@@ -1,120 +0,0 @@
-describe :net_ftp_puttextfile, shared: true do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @local_fixture_file  = File.dirname(__FILE__) + "/../fixtures/puttextfile"
-    @remote_tmp_file = tmp("textfile", false)
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-    @ftp.binary = @binary_mode
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @remote_tmp_file
-  end
-
-  it "sends the STOR command to the server" do
-    @ftp.send(@method, @local_fixture_file, "text")
-    @ftp.last_response.should == "200 OK, Data received. (STOR text)\n"
-  end
-
-  it "sends the contents of the passed local_file, using \\r\\n as the newline separator" do
-    @ftp.send(@method, @local_fixture_file, "text")
-
-    remote_lines = open(@remote_tmp_file,    "rb") {|f| f.read }
-    local_lines  = open(@local_fixture_file, "rb") {|f| f.read }
-
-    remote_lines.should_not == local_lines
-    remote_lines.should == local_lines.gsub("\n", "\r\n")
-  end
-
-  it "returns nil" do
-    @ftp.send(@method, @local_fixture_file, "text").should be_nil
-  end
-
-  describe "when passed a block" do
-    it "yields each transmitted line" do
-      res = []
-      @ftp.send(@method, @local_fixture_file, "text") { |x| res << x }
-      res.should == [
-        "This is an example file\r\n",
-        "which is going to be transmitted\r\n",
-        "using #puttextfile.\r\n"
-      ]
-    end
-  end
-
-  describe "when the STOR command fails" do
-    it "raises a Net::FTPPermError when the response code is 532" do
-      @server.should_receive(:stor).and_respond("532 Need account for storing files.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 450" do
-      @server.should_receive(:stor).and_respond("450 Requested file action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 452" do
-      @server.should_receive(:stor).and_respond("452 Requested action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 553" do
-      @server.should_receive(:stor).and_respond("553 Requested action not taken.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:stor).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:stor).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:stor).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:stor).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-  end
-
-  describe "when opening the data port fails" do
-    it "raises a Net::FTPPermError when the response code is 500" do
-      @server.should_receive(:eprt).and_respond("500 Syntax error, command unrecognized.")
-      @server.should_receive(:port).and_respond("500 Syntax error, command unrecognized.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 501" do
-      @server.should_receive(:eprt).and_respond("501 Syntax error in parameters or arguments.")
-      @server.should_receive(:port).and_respond("501 Syntax error in parameters or arguments.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-
-    it "raises a Net::FTPTempError when the response code is 421" do
-      @server.should_receive(:eprt).and_respond("421 Service not available, closing control connection.")
-      @server.should_receive(:port).and_respond("421 Service not available, closing control connection.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPTempError)
-    end
-
-    it "raises a Net::FTPPermError when the response code is 530" do
-      @server.should_receive(:eprt).and_respond("530 Not logged in.")
-      @server.should_receive(:port).and_respond("530 Not logged in.")
-      -> { @ftp.send(@method, @local_fixture_file, "text") }.should raise_error(Net::FTPPermError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/shared/pwd.rb b/spec/ruby/library/net/ftp/shared/pwd.rb
deleted file mode 100644
index 951d020f2d..0000000000
--- a/spec/ruby/library/net/ftp/shared/pwd.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-describe :net_ftp_pwd, shared: true do
-
-end
diff --git a/spec/ruby/library/net/ftp/site_spec.rb b/spec/ruby/library/net/ftp/site_spec.rb
deleted file mode 100644
index 4d6a9b4a0c..0000000000
--- a/spec/ruby/library/net/ftp/site_spec.rb
+++ /dev/null
@@ -1,53 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#site" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the SITE command with the passed argument to the server" do
-    @ftp.site("param")
-    @ftp.last_response.should == "200 Command okay. (SITE param)\n"
-  end
-
-  it "returns nil" do
-    @ftp.site("param").should be_nil
-  end
-
-  it "does not raise an error when the response code is 202" do
-    @server.should_receive(:site).and_respond("202 Command not implemented, superfluous at this site.")
-    -> { @ftp.site("param") }.should_not raise_error
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:site).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.site("param") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:site).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.site("param") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:site).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.site("param") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:site).and_respond("530 Requested action not taken.")
-    -> { @ftp.site("param") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/size_spec.rb b/spec/ruby/library/net/ftp/size_spec.rb
deleted file mode 100644
index 17615079e9..0000000000
--- a/spec/ruby/library/net/ftp/size_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#size" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the SIZE command to the server" do
-    @ftp.size("test.file")
-    @ftp.last_response.should == "213 1024\n"
-  end
-
-  it "returns the size of the passed file as Integer" do
-    @ftp.size("test.file").should eql(1024)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:size).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.size("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:size).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.size("test.file") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:size).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.size("test.file") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 550" do
-    @server.should_receive(:size).and_respond("550 Requested action not taken.")
-    -> { @ftp.size("test.file") }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/spec_helper.rb b/spec/ruby/library/net/ftp/spec_helper.rb
deleted file mode 100644
index c87d16218b..0000000000
--- a/spec/ruby/library/net/ftp/spec_helper.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require "net/ftp"
-
-if defined?(Net::FTP.default_passive)
-  Net::FTP.default_passive = false
-end
diff --git a/spec/ruby/library/net/ftp/status_spec.rb b/spec/ruby/library/net/ftp/status_spec.rb
deleted file mode 100644
index 6e3840bf93..0000000000
--- a/spec/ruby/library/net/ftp/status_spec.rb
+++ /dev/null
@@ -1,67 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#status" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the STAT command to the server" do
-    @ftp.status
-    @ftp.last_response.should == "211 System status, or system help reply. (STAT)\n"
-  end
-
-  it "sends the STAT command with an optional parameter to the server" do
-    @ftp.status("/pub").should == "211 System status, or system help reply. (STAT /pub)\n"
-  end
-
-  it "returns the received information" do
-    @ftp.status.should == "211 System status, or system help reply. (STAT)\n"
-  end
-
-  it "does not raise an error when the response code is 212" do
-    @server.should_receive(:stat).and_respond("212 Directory status.")
-    -> { @ftp.status }.should_not raise_error
-  end
-
-  it "does not raise an error when the response code is 213" do
-    @server.should_receive(:stat).and_respond("213 File status.")
-    -> { @ftp.status }.should_not raise_error
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:stat).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.status }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:stat).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.status }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:stat).and_respond("502 Command not implemented.")
-    -> { @ftp.status }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:stat).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.status }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 530" do
-    @server.should_receive(:stat).and_respond("530 Requested action not taken.")
-    -> { @ftp.status }.should raise_error(Net::FTPPermError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/storbinary_spec.rb b/spec/ruby/library/net/ftp/storbinary_spec.rb
deleted file mode 100644
index eb65db1e8d..0000000000
--- a/spec/ruby/library/net/ftp/storbinary_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#storbinary" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @local_fixture_file  = File.dirname(__FILE__) + "/fixtures/putbinaryfile"
-    @tmp_file = tmp("binaryfile", false)
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @tmp_file
-  end
-
-  it "sends the passed command and the passed File object's content to the server" do
-    File.open(@local_fixture_file) do |f|
-      f.binmode
-
-      @ftp.storbinary("STOR binary", f, 4096) {}
-      @ftp.last_response.should == "200 OK, Data received. (STOR binary)\n"
-    end
-  end
-
-  it "yields the transmitted content as binary blocks of the passed size" do
-    File.open(@local_fixture_file) do |f|
-      f.binmode
-
-      res = []
-      @ftp.storbinary("STOR binary", f, 10) { |x| res << x }
-      res.should == [
-        "This is an", " example f",
-        "ile\nwhich ", "is going t",
-        "o be trans", "mitted\nusi",
-        "ng #putbin", "aryfile.\n"
-      ]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/storlines_spec.rb b/spec/ruby/library/net/ftp/storlines_spec.rb
deleted file mode 100644
index 4affa37eee..0000000000
--- a/spec/ruby/library/net/ftp/storlines_spec.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#storlines" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @local_fixture_file  = File.dirname(__FILE__) + "/fixtures/puttextfile"
-    @tmp_file = tmp("textfile", false)
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-
-    rm_r @tmp_file
-  end
-
-  it "sends the passed command and the passed File object's content to the server" do
-    File.open(@local_fixture_file) do |f|
-      @ftp.storlines("STOR text", f) {}
-      @ftp.last_response.should == "200 OK, Data received. (STOR text)\n"
-    end
-  end
-
-  it "yields each line of the transmitted content" do
-    File.open(@local_fixture_file) do |f|
-      res = []
-      @ftp.storlines("STOR text", f) { |x| res << x }
-      res.should == [
-        "This is an example file\r\n",
-        "which is going to be transmitted\r\n",
-        "using #puttextfile.\r\n"
-      ]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/ftp/system_spec.rb b/spec/ruby/library/net/ftp/system_spec.rb
deleted file mode 100644
index 749258622d..0000000000
--- a/spec/ruby/library/net/ftp/system_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#system" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the SYST command to the server" do
-    @ftp.system
-    @ftp.last_response.should =~ /\A215 FTP Dummy Server \(SYST\)\Z/
-  end
-
-  it "returns the received information" do
-    @ftp.system.should =~ /\AFTP Dummy Server \(SYST\)\Z/
-  end
-
-  it "raises a Net::FTPPermError when the response code is 500" do
-    @server.should_receive(:syst).and_respond("500 Syntax error, command unrecognized.")
-    -> { @ftp.system }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 501" do
-    @server.should_receive(:syst).and_respond("501 Syntax error in parameters or arguments.")
-    -> { @ftp.system }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 502" do
-    @server.should_receive(:syst).and_respond("502 Command not implemented.")
-    -> { @ftp.system }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 421" do
-    @server.should_receive(:syst).and_respond("421 Service not available, closing control connection.")
-    -> { @ftp.system }.should raise_error(Net::FTPTempError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/voidcmd_spec.rb b/spec/ruby/library/net/ftp/voidcmd_spec.rb
deleted file mode 100644
index 3673c7fd5b..0000000000
--- a/spec/ruby/library/net/ftp/voidcmd_spec.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#voidcmd" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "sends the passed command to the server" do
-    @server.should_receive(:help).and_respond("2xx Does not raise.")
-    -> { @ftp.voidcmd("HELP") }.should_not raise_error
-  end
-
-  it "returns nil" do
-    @server.should_receive(:help).and_respond("2xx Does not raise.")
-    @ftp.voidcmd("HELP").should be_nil
-  end
-
-  it "raises a Net::FTPReplyError when the response code is 1xx" do
-    @server.should_receive(:help).and_respond("1xx Does raise a Net::FTPReplyError.")
-    -> { @ftp.voidcmd("HELP")  }.should raise_error(Net::FTPReplyError)
-  end
-
-  it "raises a Net::FTPReplyError when the response code is 3xx" do
-    @server.should_receive(:help).and_respond("3xx Does raise a Net::FTPReplyError.")
-    -> { @ftp.voidcmd("HELP") }.should raise_error(Net::FTPReplyError)
-  end
-
-  it "raises a Net::FTPTempError when the response code is 4xx" do
-    @server.should_receive(:help).and_respond("4xx Does raise a Net::FTPTempError.")
-    -> { @ftp.voidcmd("HELP") }.should raise_error(Net::FTPTempError)
-  end
-
-  it "raises a Net::FTPPermError when the response code is 5xx" do
-    @server.should_receive(:help).and_respond("5xx Does raise a Net::FTPPermError.")
-    -> { @ftp.voidcmd("HELP") }.should raise_error(Net::FTPPermError)
-  end
-
-  it "raises a Net::FTPProtoError when the response code is not valid" do
-    @server.should_receive(:help).and_respond("999 Does raise a Net::FTPProtoError.")
-    -> { @ftp.voidcmd("HELP") }.should raise_error(Net::FTPProtoError)
-  end
-end
diff --git a/spec/ruby/library/net/ftp/welcome_spec.rb b/spec/ruby/library/net/ftp/welcome_spec.rb
deleted file mode 100644
index a0d7483949..0000000000
--- a/spec/ruby/library/net/ftp/welcome_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'spec_helper'
-require_relative 'fixtures/server'
-
-describe "Net::FTP#welcome" do
-  before :each do
-    @server = NetFTPSpecs::DummyFTP.new
-    @server.serve_once
-
-    @ftp = Net::FTP.new
-    @ftp.connect(@server.hostname, @server.server_port)
-  end
-
-  after :each do
-    @ftp.quit rescue nil
-    @ftp.close
-    @server.stop
-  end
-
-  it "returns the server's welcome message" do
-    @ftp.welcome.should be_nil
-    @ftp.login
-    @ftp.welcome.should == "230 User logged in, proceed. (USER anonymous)\n"
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPBadResponse_spec.rb b/spec/ruby/library/net/http/HTTPBadResponse_spec.rb
deleted file mode 100644
index be644968f5..0000000000
--- a/spec/ruby/library/net/http/HTTPBadResponse_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPBadResponse" do
-  it "is a subclass of StandardError" do
-    Net::HTTPBadResponse.should < StandardError
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb b/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb
deleted file mode 100644
index 08347464ec..0000000000
--- a/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-ruby_version_is "2.6" do
-  describe "Net::HTTPClientException" do
-    it "is a subclass of Net::ProtoServerError" do
-      Net::HTTPClientException.should < Net::ProtoServerError
-    end
-
-    it "includes the Net::HTTPExceptions module" do
-      Net::HTTPClientException.should < Net::HTTPExceptions
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPError_spec.rb b/spec/ruby/library/net/http/HTTPError_spec.rb
deleted file mode 100644
index ab5f491bb7..0000000000
--- a/spec/ruby/library/net/http/HTTPError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPError" do
-  it "is a subclass of Net::ProtocolError" do
-    Net::HTTPError.should < Net::ProtocolError
-  end
-
-  it "includes the Net::HTTPExceptions module" do
-    Net::HTTPError.should < Net::HTTPExceptions
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPFatalError_spec.rb b/spec/ruby/library/net/http/HTTPFatalError_spec.rb
deleted file mode 100644
index 6ab36bff6c..0000000000
--- a/spec/ruby/library/net/http/HTTPFatalError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPFatalError" do
-  it "is a subclass of Net::ProtoFatalError" do
-    Net::HTTPFatalError.should < Net::ProtoFatalError
-  end
-
-  it "includes the Net::HTTPExceptions module" do
-    Net::HTTPFatalError.should < Net::HTTPExceptions
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPHeaderSyntaxError_spec.rb b/spec/ruby/library/net/http/HTTPHeaderSyntaxError_spec.rb
deleted file mode 100644
index 38e9454f99..0000000000
--- a/spec/ruby/library/net/http/HTTPHeaderSyntaxError_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPHeaderSyntaxError" do
-  it "is a subclass of StandardError" do
-    Net::HTTPHeaderSyntaxError.should < StandardError
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPRetriableError_spec.rb b/spec/ruby/library/net/http/HTTPRetriableError_spec.rb
deleted file mode 100644
index 3a4bb9146c..0000000000
--- a/spec/ruby/library/net/http/HTTPRetriableError_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPRetriableError" do
-  it "is a subclass of Net::ProtoRetriableError" do
-    Net::HTTPRetriableError.should < Net::ProtoRetriableError
-  end
-
-  it "includes the Net::HTTPExceptions module" do
-    Net::HTTPRetriableError.should < Net::HTTPExceptions
-  end
-end
diff --git a/spec/ruby/library/net/http/HTTPServerException_spec.rb b/spec/ruby/library/net/http/HTTPServerException_spec.rb
deleted file mode 100644
index 87841ab499..0000000000
--- a/spec/ruby/library/net/http/HTTPServerException_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-require_relative '../../../spec_helper'
-require 'net/http'
-
-ruby_version_is ""..."2.6" do
-  describe "Net::HTTPServerException" do
-    it "is a subclass of Net::ProtoServerError" do
-      Net::HTTPServerException.should < Net::ProtoServerError
-    end
-
-    it "includes the Net::HTTPExceptions module" do
-      Net::HTTPServerException.should < Net::HTTPExceptions
-    end
-  end
-end
-
-ruby_version_is "2.6" do
-  describe "Net::HTTPServerException" do
-    it "is a subclass of Net::ProtoServerError and is warned as deprecated" do
-      -> { Net::HTTPServerException.should < Net::ProtoServerError }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
-    end
-
-    it "includes the Net::HTTPExceptions module and is warned as deprecated" do
-      -> { Net::HTTPServerException.should < Net::HTTPExceptions }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/Proxy_spec.rb b/spec/ruby/library/net/http/http/Proxy_spec.rb
deleted file mode 100644
index f85ccc0ee9..0000000000
--- a/spec/ruby/library/net/http/http/Proxy_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.Proxy" do
-  it "returns a new subclass of Net::HTTP" do
-    Net::HTTP.Proxy("localhost").should < Net::HTTP
-  end
-
-  it "returns Net::HTTP when the passed address is nil" do
-    Net::HTTP.Proxy(nil).should == Net::HTTP
-  end
-
-  it "sets the returned subclasses' proxy options based on the passed arguments" do
-    http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-    http_with_proxy.proxy_address.should == "localhost"
-    http_with_proxy.proxy_port.should eql(1234)
-    http_with_proxy.proxy_user.should == "rspec"
-    http_with_proxy.proxy_pass.should == "rocks"
-  end
-end
-
-describe "Net::HTTP#proxy?" do
-  describe "when self is no proxy class instance" do
-    it "returns false" do
-      Net::HTTP.new("localhost", 3333).proxy?.should be_false
-    end
-  end
-
-  describe "when self is a proxy class instance" do
-    it "returns false" do
-      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-      http_with_proxy.new("localhost", 3333).proxy?.should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/active_spec.rb b/spec/ruby/library/net/http/http/active_spec.rb
deleted file mode 100644
index ef657243ba..0000000000
--- a/spec/ruby/library/net/http/http/active_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/started'
-
-describe "Net::HTTP#active?" do
-  it_behaves_like :net_http_started_p, :active?
-end
diff --git a/spec/ruby/library/net/http/http/address_spec.rb b/spec/ruby/library/net/http/http/address_spec.rb
deleted file mode 100644
index 5fce76d767..0000000000
--- a/spec/ruby/library/net/http/http/address_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#address" do
-  it "returns the current host name" do
-    net = Net::HTTP.new("localhost")
-    net.address.should == "localhost"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/close_on_empty_response_spec.rb b/spec/ruby/library/net/http/http/close_on_empty_response_spec.rb
deleted file mode 100644
index a97b7b6c43..0000000000
--- a/spec/ruby/library/net/http/http/close_on_empty_response_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#close_on_empty_response" do
-  it "needs to be reviewed for spec completeness"
-end
-
-describe "Net::HTTP#close_on_empty_response=" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/library/net/http/http/copy_spec.rb b/spec/ruby/library/net/http/http/copy_spec.rb
deleted file mode 100644
index 5ebfdc334e..0000000000
--- a/spec/ruby/library/net/http/http/copy_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#copy" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a COPY request to the passed path and returns the response" do
-    response = @http.copy("/request")
-    response.should be_kind_of(Net::HTTPResponse)
-    response.body.should == "Request type: COPY"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/default_port_spec.rb b/spec/ruby/library/net/http/http/default_port_spec.rb
deleted file mode 100644
index 30db18efae..0000000000
--- a/spec/ruby/library/net/http/http/default_port_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.default_port" do
-  it "returns 80" do
-    Net::HTTP.http_default_port.should eql(80)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/delete_spec.rb b/spec/ruby/library/net/http/http/delete_spec.rb
deleted file mode 100644
index 160c653115..0000000000
--- a/spec/ruby/library/net/http/http/delete_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#delete" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a DELETE request to the passed path and returns the response" do
-    response = @http.delete("/request")
-    response.should be_kind_of(Net::HTTPResponse)
-    response.body.should == "Request type: DELETE"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/finish_spec.rb b/spec/ruby/library/net/http/http/finish_spec.rb
deleted file mode 100644
index f98bc7be13..0000000000
--- a/spec/ruby/library/net/http/http/finish_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#finish" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when self has been started" do
-    it "closes the tcp connection" do
-      @http.start
-      @http.finish
-      @http.started?.should be_false
-    end
-  end
-
-  describe "when self has not been started yet" do
-    it "raises an IOError" do
-      -> { @http.finish }.should raise_error(IOError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/fixtures/http_server.rb b/spec/ruby/library/net/http/http/fixtures/http_server.rb
deleted file mode 100644
index 49e8f437cc..0000000000
--- a/spec/ruby/library/net/http/http/fixtures/http_server.rb
+++ /dev/null
@@ -1,105 +0,0 @@
-require 'webrick'
-require 'webrick/httpservlet/abstract'
-
-module NetHTTPSpecs
-  class NullWriter
-    def <<(s) end
-    def puts(*args) end
-    def print(*args) end
-    def printf(*args) end
-  end
-
-  class SpecServlet < WEBrick::HTTPServlet::AbstractServlet
-    def handle(req, res)
-      reply(req, res)
-    end
-
-    %w{ do_GET do_HEAD do_POST do_PUT do_PROPPATCH do_LOCK do_UNLOCK
-        do_OPTIONS do_PROPFIND do_DELETE do_MOVE do_COPY
-        do_MKCOL do_TRACE }.each do |method|
-      alias_method method.to_sym, :handle
-    end
-  end
-
-  class RequestServlet < SpecServlet
-    def reply(req, res)
-      res.content_type = "text/plain"
-      res.body = "Request type: #{req.request_method}"
-    end
-  end
-
-  class RequestBodyServlet < SpecServlet
-    def reply(req, res)
-      res.content_type = "text/plain"
-      res.body = req.body
-    end
-  end
-
-  class RequestHeaderServlet < SpecServlet
-    def reply(req, res)
-      res.content_type = "text/plain"
-      res.body = req.header.inspect
-    end
-  end
-
-  class RequestBasicAuthServlet < SpecServlet
-    def reply(req, res)
-      res.content_type = "text/plain"
-
-      WEBrick::HTTPAuth.basic_auth(req, res, "realm") do |user, pass|
-        res.body = "username: #{user}\npassword: #{pass}"
-        true
-      end
-    end
-  end
-
-  class << self
-    @server = nil
-    @server_thread = nil
-
-    def port
-      raise "server not started" unless @server
-      @server.config[:Port]
-    end
-
-    def start_server
-      server_config = {
-        BindAddress: "127.0.0.1",
-        Port: 0,
-        Logger: WEBrick::Log.new(NullWriter.new),
-        AccessLog: [],
-        ServerType: Thread
-      }
-
-      @server = WEBrick::HTTPServer.new(server_config)
-
-      @server.mount_proc('/') do |req, res|
-        res.content_type = "text/plain"
-        res.body = "This is the index page."
-      end
-      @server.mount('/request', RequestServlet)
-      @server.mount("/request/body", RequestBodyServlet)
-      @server.mount("/request/header", RequestHeaderServlet)
-      @server.mount("/request/basic_auth", RequestBasicAuthServlet)
-
-      @server_thread = @server.start
-    end
-
-    def stop_server
-      if @server
-        begin
-          @server.shutdown
-        rescue Errno::EPIPE
-          # Because WEBrick is not thread-safe and only catches IOError
-        end
-        @server = nil
-      end
-      if @server_thread
-        @server_thread.join
-        @server_thread = nil
-      end
-      timeout = WEBrick::Utils::TimeoutHandler
-      timeout.terminate if timeout.respond_to?(:terminate)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/get2_spec.rb b/spec/ruby/library/net/http/http/get2_spec.rb
deleted file mode 100644
index 71dfc3d39b..0000000000
--- a/spec/ruby/library/net/http/http/get2_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_get'
-
-describe "Net::HTTP#get2" do
-  it_behaves_like :net_ftp_request_get, :get2
-end
diff --git a/spec/ruby/library/net/http/http/get_print_spec.rb b/spec/ruby/library/net/http/http/get_print_spec.rb
deleted file mode 100644
index f59dd68c81..0000000000
--- a/spec/ruby/library/net/http/http/get_print_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.get_print" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed URI" do
-    it "it prints the body of the specified uri to $stdout" do
-      -> do
-        Net::HTTP.get_print URI.parse("http://localhost:#{@port}/")
-      end.should output(/This is the index page\./)
-    end
-  end
-
-  describe "when passed host, path, port" do
-    it "it prints the body of the specified uri to $stdout" do
-      -> do
-        Net::HTTP.get_print 'localhost', "/", @port
-      end.should output(/This is the index page\./)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/get_response_spec.rb b/spec/ruby/library/net/http/http/get_response_spec.rb
deleted file mode 100644
index 941b35e773..0000000000
--- a/spec/ruby/library/net/http/http/get_response_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.get_response" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed URI" do
-    it "returns the response for the specified uri" do
-      res = Net::HTTP.get_response(URI.parse("http://localhost:#{@port}/"))
-      res.content_type.should == "text/plain"
-      res.body.should == "This is the index page."
-    end
-  end
-
-  describe "when passed host, path, port" do
-    it "returns the response for the specified host-path-combination" do
-      res = Net::HTTP.get_response('localhost', "/", @port)
-      res.content_type.should == "text/plain"
-      res.body.should == "This is the index page."
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/get_spec.rb b/spec/ruby/library/net/http/http/get_spec.rb
deleted file mode 100644
index 4b8af5950a..0000000000
--- a/spec/ruby/library/net/http/http/get_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.get when passed URI" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed URI" do
-    it "returns the body of the specified uri" do
-      Net::HTTP.get(URI.parse("http://localhost:#{@port}/")).should == "This is the index page."
-    end
-  end
-
-  describe "when passed host, path, port" do
-    it "returns the body of the specified host-path-combination" do
-      Net::HTTP.get('localhost', "/", @port).should == "This is the index page."
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/head2_spec.rb b/spec/ruby/library/net/http/http/head2_spec.rb
deleted file mode 100644
index 606798e4af..0000000000
--- a/spec/ruby/library/net/http/http/head2_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_head'
-
-describe "Net::HTTP#head2" do
-  it_behaves_like :net_ftp_request_head, :head2
-end
diff --git a/spec/ruby/library/net/http/http/head_spec.rb b/spec/ruby/library/net/http/http/head_spec.rb
deleted file mode 100644
index 925a8e6043..0000000000
--- a/spec/ruby/library/net/http/http/head_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#head" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a HEAD request to the passed path and returns the response" do
-    response = @http.head("/request")
-    # HEAD requests have no responses
-    response.body.should be_nil
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.head("/request").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/http_default_port_spec.rb b/spec/ruby/library/net/http/http/http_default_port_spec.rb
deleted file mode 100644
index cf7f73e630..0000000000
--- a/spec/ruby/library/net/http/http/http_default_port_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.http_default_port" do
-  it "returns 80" do
-    Net::HTTP.http_default_port.should eql(80)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/https_default_port_spec.rb b/spec/ruby/library/net/http/http/https_default_port_spec.rb
deleted file mode 100644
index fbf0bd1abc..0000000000
--- a/spec/ruby/library/net/http/http/https_default_port_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.https_default_port" do
-  it "returns 443" do
-    Net::HTTP.https_default_port.should eql(443)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/initialize_spec.rb b/spec/ruby/library/net/http/http/initialize_spec.rb
deleted file mode 100644
index 7683713a0e..0000000000
--- a/spec/ruby/library/net/http/http/initialize_spec.rb
+++ /dev/null
@@ -1,46 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#initialize" do
-  it "is private" do
-    Net::HTTP.should have_private_instance_method(:initialize)
-  end
-
-  describe "when passed address" do
-    before :each do
-      @net = Net::HTTP.allocate
-      @net.send(:initialize, "localhost")
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @net.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the default HTTP port" do
-      @net.port.should eql(Net::HTTP.default_port)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @net.started?.should be_false
-    end
-  end
-
-  describe "when passed address, port" do
-    before :each do
-      @net = Net::HTTP.allocate
-      @net.send(:initialize, "localhost", 3333)
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @net.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the passed port" do
-      @net.port.should eql(3333)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @net.started?.should be_false
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/inspect_spec.rb b/spec/ruby/library/net/http/http/inspect_spec.rb
deleted file mode 100644
index b1e799ca34..0000000000
--- a/spec/ruby/library/net/http/http/inspect_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#inspect" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-    @http = Net::HTTP.new("localhost", @port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "returns a String representation of self" do
-    @http.inspect.should be_kind_of(String)
-    @http.inspect.should == "#<Net::HTTP localhost:#{@port} open=false>"
-
-    @http.start
-    @http.inspect.should == "#<Net::HTTP localhost:#{@port} open=true>"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/is_version_1_1_spec.rb b/spec/ruby/library/net/http/http/is_version_1_1_spec.rb
deleted file mode 100644
index f37695b777..0000000000
--- a/spec/ruby/library/net/http/http/is_version_1_1_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/version_1_1'
-
-describe "Net::HTTP.is_version_1_1?" do
-  it_behaves_like :net_http_version_1_1_p, :is_version_1_1?
-end
diff --git a/spec/ruby/library/net/http/http/is_version_1_2_spec.rb b/spec/ruby/library/net/http/http/is_version_1_2_spec.rb
deleted file mode 100644
index 82dbdc87aa..0000000000
--- a/spec/ruby/library/net/http/http/is_version_1_2_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/version_1_2'
-
-describe "Net::HTTP.is_version_1_2?" do
-  it_behaves_like :net_http_version_1_2_p, :is_version_1_2?
-end
diff --git a/spec/ruby/library/net/http/http/lock_spec.rb b/spec/ruby/library/net/http/http/lock_spec.rb
deleted file mode 100644
index bb76607a8b..0000000000
--- a/spec/ruby/library/net/http/http/lock_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#lock" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a LOCK request to the passed path and returns the response" do
-    response = @http.lock("/request", "test=test")
-    response.should be_kind_of(Net::HTTPResponse)
-    response.body.should == "Request type: LOCK"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/mkcol_spec.rb b/spec/ruby/library/net/http/http/mkcol_spec.rb
deleted file mode 100644
index 33017625e2..0000000000
--- a/spec/ruby/library/net/http/http/mkcol_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#mkcol" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a MKCOL request to the passed path and returns the response" do
-    response = @http.mkcol("/request")
-    response.should be_kind_of(Net::HTTPResponse)
-    response.body.should == "Request type: MKCOL"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/move_spec.rb b/spec/ruby/library/net/http/http/move_spec.rb
deleted file mode 100644
index 4d6b828150..0000000000
--- a/spec/ruby/library/net/http/http/move_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#head" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a MOVE request to the passed path and returns the response" do
-    response = @http.move("/request")
-    # HEAD requests have no responses
-    response.body.should == "Request type: MOVE"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.move("/request").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/new_spec.rb b/spec/ruby/library/net/http/http/new_spec.rb
deleted file mode 100644
index 491d1d01fd..0000000000
--- a/spec/ruby/library/net/http/http/new_spec.rb
+++ /dev/null
@@ -1,86 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.new" do
-  describe "when passed address" do
-    before :each do
-      @http = Net::HTTP.new("localhost")
-    end
-
-    it "returns a Net::HTTP instance" do
-      @http.proxy?.should be_false
-      @http.instance_of?(Net::HTTP).should be_true
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @http.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the default HTTP port" do
-      @http.port.should eql(Net::HTTP.default_port)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @http.started?.should be_false
-    end
-  end
-
-  describe "when passed address, port" do
-    before :each do
-      @http = Net::HTTP.new("localhost", 3333)
-    end
-
-    it "returns a Net::HTTP instance" do
-      @http.proxy?.should be_false
-      @http.instance_of?(Net::HTTP).should be_true
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @http.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the passed port" do
-      @http.port.should eql(3333)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @http.started?.should be_false
-    end
-  end
-
-  describe "when passed address, port, *proxy_options" do
-    it "returns a Net::HTTP instance" do
-      http = Net::HTTP.new("localhost", 3333, "localhost")
-      http.proxy?.should be_true
-      http.instance_of?(Net::HTTP).should be_true
-      http.should be_kind_of(Net::HTTP)
-    end
-
-    it "correctly sets the passed Proxy options" do
-      http = Net::HTTP.new("localhost", 3333, "localhost")
-      http.proxy_address.should == "localhost"
-      http.proxy_port.should eql(80)
-      http.proxy_user.should be_nil
-      http.proxy_pass.should be_nil
-
-      http = Net::HTTP.new("localhost", 3333, "localhost", 1234)
-      http.proxy_address.should == "localhost"
-      http.proxy_port.should eql(1234)
-      http.proxy_user.should be_nil
-      http.proxy_pass.should be_nil
-
-      http = Net::HTTP.new("localhost", 3333, "localhost", 1234, "rubyspec")
-      http.proxy_address.should == "localhost"
-      http.proxy_port.should eql(1234)
-      http.proxy_user.should == "rubyspec"
-      http.proxy_pass.should be_nil
-
-      http = Net::HTTP.new("localhost", 3333, "localhost", 1234, "rubyspec", "rocks")
-      http.proxy_address.should == "localhost"
-      http.proxy_port.should eql(1234)
-      http.proxy_user.should == "rubyspec"
-      http.proxy_pass.should == "rocks"
-    end
-  end
-
-end
diff --git a/spec/ruby/library/net/http/http/newobj_spec.rb b/spec/ruby/library/net/http/http/newobj_spec.rb
deleted file mode 100644
index b261dcc5db..0000000000
--- a/spec/ruby/library/net/http/http/newobj_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.newobj" do
-  before :each do
-    @net = Net::HTTP.newobj("localhost")
-  end
-
-  describe "when passed address" do
-    it "returns a new Net::HTTP instance" do
-      @net.should be_kind_of(Net::HTTP)
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @net.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the default HTTP port" do
-      @net.port.should eql(Net::HTTP.default_port)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @net.started?.should be_false
-    end
-  end
-
-  describe "when passed address, port" do
-    before :each do
-      @net = Net::HTTP.newobj("localhost", 3333)
-    end
-
-    it "returns a new Net::HTTP instance" do
-      @net.should be_kind_of(Net::HTTP)
-    end
-
-    it "sets the new Net::HTTP instance's address to the passed address" do
-      @net.address.should == "localhost"
-    end
-
-    it "sets the new Net::HTTP instance's port to the passed port" do
-      @net.port.should eql(3333)
-    end
-
-    it "does not start the new Net::HTTP instance" do
-      @net.started?.should be_false
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/open_timeout_spec.rb b/spec/ruby/library/net/http/http/open_timeout_spec.rb
deleted file mode 100644
index 44b33615e6..0000000000
--- a/spec/ruby/library/net/http/http/open_timeout_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#open_timeout" do
-  it "returns the seconds to wait till the connection is open" do
-    net = Net::HTTP.new("localhost")
-    net.open_timeout.should eql(60)
-    net.open_timeout = 10
-    net.open_timeout.should eql(10)
-  end
-end
-
-describe "Net::HTTP#open_timeout=" do
-  it "sets the seconds to wait till the connection is open" do
-    net = Net::HTTP.new("localhost")
-    net.open_timeout = 10
-    net.open_timeout.should eql(10)
-  end
-
-  it "returns the newly set value" do
-    net = Net::HTTP.new("localhost")
-    (net.open_timeout = 10).should eql(10)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/options_spec.rb b/spec/ruby/library/net/http/http/options_spec.rb
deleted file mode 100644
index d798e69197..0000000000
--- a/spec/ruby/library/net/http/http/options_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#options" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an options request to the passed path and returns the response" do
-    response = @http.options("/request")
-
-    response.body.should == "Request type: OPTIONS"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.options("/request").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/port_spec.rb b/spec/ruby/library/net/http/http/port_spec.rb
deleted file mode 100644
index 7de295ca75..0000000000
--- a/spec/ruby/library/net/http/http/port_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#port" do
-  it "returns the current port number" do
-    net = Net::HTTP.new("localhost", 3333)
-    net.port.should eql(3333)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/post2_spec.rb b/spec/ruby/library/net/http/http/post2_spec.rb
deleted file mode 100644
index eab9a6a1d2..0000000000
--- a/spec/ruby/library/net/http/http/post2_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_post'
-
-describe "Net::HTTP#post2" do
-  it_behaves_like :net_ftp_request_post, :post2
-end
diff --git a/spec/ruby/library/net/http/http/post_form_spec.rb b/spec/ruby/library/net/http/http/post_form_spec.rb
deleted file mode 100644
index 891e05e7af..0000000000
--- a/spec/ruby/library/net/http/http/post_form_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.post_form when passed URI" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  it "POSTs the passed form data to the given uri" do
-    uri = URI.parse("http://localhost:#{@port}/request/body")
-    data = { test: :data }
-
-    res = Net::HTTP.post_form(uri, data)
-    res.body.should == "test=data"
-  end
-end
diff --git a/spec/ruby/library/net/http/http/post_spec.rb b/spec/ruby/library/net/http/http/post_spec.rb
deleted file mode 100644
index 9f20a03c85..0000000000
--- a/spec/ruby/library/net/http/http/post_spec.rb
+++ /dev/null
@@ -1,74 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require 'uri'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.post" do
-  before :each do
-    NetHTTPSpecs.start_server
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends post request to the specified URI and returns response" do
-    response = Net::HTTP.post(
-      URI("http://localhost:#{NetHTTPSpecs.port}/request"),
-      '{ "q": "ruby", "max": "50" }',
-      "Content-Type" => "application/json")
-    response.body.should == "Request type: POST"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    response = Net::HTTP.post(URI("http://localhost:#{NetHTTPSpecs.port}/request"), "test=test")
-    response.should be_kind_of(Net::HTTPResponse)
-  end
-
-  it "sends Content-Type: application/x-www-form-urlencoded by default" do
-    response = Net::HTTP.post(URI("http://localhost:#{NetHTTPSpecs.port}/request/header"), "test=test")
-    response.body.should include('"content-type"=>["application/x-www-form-urlencoded"]')
-  end
-
-  it "does not support HTTP Basic Auth" do
-    response = Net::HTTP.post(
-      URI("http://john:qwerty@localhost:#{NetHTTPSpecs.port}/request/basic_auth"),
-      "test=test")
-    response.body.should == "username: \npassword: "
-  end
-end
-
-describe "Net::HTTP#post" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an post request to the passed path and returns the response" do
-    response = @http.post("/request", "test=test")
-    response.body.should == "Request type: POST"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.post("/request", "test=test").should be_kind_of(Net::HTTPResponse)
-  end
-
-  describe "when passed a block" do
-    it "yields fragments of the response body to the passed block" do
-      str = ""
-      @http.post("/request", "test=test") do |res|
-        str << res
-      end
-      str.should == "Request type: POST"
-    end
-
-    it "returns a Net::HTTPResponse" do
-      @http.post("/request", "test=test") {}.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/propfind_spec.rb b/spec/ruby/library/net/http/http/propfind_spec.rb
deleted file mode 100644
index 5240171618..0000000000
--- a/spec/ruby/library/net/http/http/propfind_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#propfind" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an propfind request to the passed path and returns the response" do
-    response = @http.propfind("/request", "test=test")
-    response.body.should == "Request type: PROPFIND"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.propfind("/request", "test=test").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proppatch_spec.rb b/spec/ruby/library/net/http/http/proppatch_spec.rb
deleted file mode 100644
index 7a761a9f23..0000000000
--- a/spec/ruby/library/net/http/http/proppatch_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#proppatch" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an proppatch request to the passed path and returns the response" do
-    response = @http.proppatch("/request", "test=test")
-    response.body.should == "Request type: PROPPATCH"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.proppatch("/request", "test=test").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proxy_address_spec.rb b/spec/ruby/library/net/http/http/proxy_address_spec.rb
deleted file mode 100644
index 8d152b8d44..0000000000
--- a/spec/ruby/library/net/http/http/proxy_address_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.proxy_address" do
-  describe "when self is no proxy class" do
-    it "returns nil" do
-      Net::HTTP.proxy_address.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class" do
-    it "returns the address for self's proxy connection" do
-      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_address.should == "localhost"
-    end
-  end
-end
-
-describe "Net::HTTP#proxy_address" do
-  describe "when self is no proxy class instance" do
-    it "returns nil" do
-      Net::HTTP.new("localhost", 3333).proxy_address.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class instance" do
-    it "returns the password for self's proxy connection" do
-      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-      http_with_proxy.new("localhost", 3333).proxy_address.should == "localhost"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proxy_class_spec.rb b/spec/ruby/library/net/http/http/proxy_class_spec.rb
deleted file mode 100644
index 2d32a39f01..0000000000
--- a/spec/ruby/library/net/http/http/proxy_class_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.proxy_class?" do
-  it "returns true if self is a class created with Net::HTTP.Proxy" do
-    Net::HTTP.proxy_class?.should be_false
-    Net::HTTP.Proxy("localhost").proxy_class?.should be_true
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proxy_pass_spec.rb b/spec/ruby/library/net/http/http/proxy_pass_spec.rb
deleted file mode 100644
index 94a0034544..0000000000
--- a/spec/ruby/library/net/http/http/proxy_pass_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.proxy_pass" do
-  describe "when self is no proxy class" do
-    it "returns nil" do
-      Net::HTTP.proxy_pass.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class" do
-    it "returns nil if no password was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").proxy_pass.should be_nil
-    end
-
-    it "returns the password for self's proxy connection" do
-      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_pass.should == "rocks"
-    end
-  end
-end
-
-describe "Net::HTTP#proxy_pass" do
-  describe "when self is no proxy class instance" do
-    it "returns nil" do
-      Net::HTTP.new("localhost", 3333).proxy_pass.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class instance" do
-    it "returns nil if no password was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_pass.should be_nil
-    end
-
-    it "returns the password for self's proxy connection" do
-      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-      http_with_proxy.new("localhost", 3333).proxy_pass.should == "rocks"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proxy_port_spec.rb b/spec/ruby/library/net/http/http/proxy_port_spec.rb
deleted file mode 100644
index 339f7ee850..0000000000
--- a/spec/ruby/library/net/http/http/proxy_port_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.proxy_port" do
-  describe "when self is no proxy class" do
-    it "returns nil" do
-      Net::HTTP.proxy_port.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class" do
-    it "returns 80 if no port was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").proxy_port.should eql(80)
-    end
-
-    it "returns the port for self's proxy connection" do
-      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_port.should eql(1234)
-    end
-  end
-end
-
-describe "Net::HTTP#proxy_port" do
-  describe "when self is no proxy class instance" do
-    it "returns nil" do
-      Net::HTTP.new("localhost", 3333).proxy_port.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class instance" do
-    it "returns 80 if no port was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_port.should eql(80)
-    end
-
-    it "returns the port for self's proxy connection" do
-      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-      http_with_proxy.new("localhost", 3333).proxy_port.should eql(1234)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/proxy_user_spec.rb b/spec/ruby/library/net/http/http/proxy_user_spec.rb
deleted file mode 100644
index 01fda400e9..0000000000
--- a/spec/ruby/library/net/http/http/proxy_user_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.proxy_user" do
-  describe "when self is no proxy class" do
-    it "returns nil" do
-      Net::HTTP.proxy_user.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class" do
-    it "returns nil if no username was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").proxy_user.should be_nil
-    end
-
-    it "returns the username for self's proxy connection" do
-      Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks").proxy_user.should == "rspec"
-    end
-  end
-end
-
-describe "Net::HTTP#proxy_user" do
-  describe "when self is no proxy class instance" do
-    it "returns nil" do
-      Net::HTTP.new("localhost", 3333).proxy_user.should be_nil
-    end
-  end
-
-  describe "when self is a proxy class instance" do
-    it "returns nil if no username was set for self's proxy connection" do
-      Net::HTTP.Proxy("localhost").new("localhost", 3333).proxy_user.should be_nil
-    end
-
-    it "returns the username for self's proxy connection" do
-      http_with_proxy = Net::HTTP.Proxy("localhost", 1234, "rspec", "rocks")
-      http_with_proxy.new("localhost", 3333).proxy_user.should == "rspec"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/put2_spec.rb b/spec/ruby/library/net/http/http/put2_spec.rb
deleted file mode 100644
index 0ee3590639..0000000000
--- a/spec/ruby/library/net/http/http/put2_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_put'
-
-describe "Net::HTTP#put2" do
-  it_behaves_like :net_ftp_request_put, :put2
-end
diff --git a/spec/ruby/library/net/http/http/put_spec.rb b/spec/ruby/library/net/http/http/put_spec.rb
deleted file mode 100644
index 3ca0d0963e..0000000000
--- a/spec/ruby/library/net/http/http/put_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#put" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an put request to the passed path and returns the response" do
-    response = @http.put("/request", "test=test")
-    response.body.should == "Request type: PUT"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.put("/request", "test=test").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/read_timeout_spec.rb b/spec/ruby/library/net/http/http/read_timeout_spec.rb
deleted file mode 100644
index e23ee76025..0000000000
--- a/spec/ruby/library/net/http/http/read_timeout_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#read_timeout" do
-  it "returns the seconds to wait until reading one block" do
-    net = Net::HTTP.new("localhost")
-    net.read_timeout.should eql(60)
-    net.read_timeout = 10
-    net.read_timeout.should eql(10)
-  end
-end
-
-describe "Net::HTTP#read_timeout=" do
-  it "sets the seconds to wait till the connection is open" do
-    net = Net::HTTP.new("localhost")
-    net.read_timeout = 10
-    net.read_timeout.should eql(10)
-  end
-
-  it "returns the newly set value" do
-    net = Net::HTTP.new("localhost")
-    (net.read_timeout = 10).should eql(10)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/request_get_spec.rb b/spec/ruby/library/net/http/http/request_get_spec.rb
deleted file mode 100644
index f53a2e9d65..0000000000
--- a/spec/ruby/library/net/http/http/request_get_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_get'
-
-describe "Net::HTTP#request_get" do
-  it_behaves_like :net_ftp_request_get, :get2
-end
diff --git a/spec/ruby/library/net/http/http/request_head_spec.rb b/spec/ruby/library/net/http/http/request_head_spec.rb
deleted file mode 100644
index dc47557b9d..0000000000
--- a/spec/ruby/library/net/http/http/request_head_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_head'
-
-describe "Net::HTTP#request_head" do
-  it_behaves_like :net_ftp_request_head, :request_head
-end
diff --git a/spec/ruby/library/net/http/http/request_post_spec.rb b/spec/ruby/library/net/http/http/request_post_spec.rb
deleted file mode 100644
index 0b408fa84d..0000000000
--- a/spec/ruby/library/net/http/http/request_post_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_post'
-
-describe "Net::HTTP#request_post" do
-  it_behaves_like :net_ftp_request_post, :request_post
-end
diff --git a/spec/ruby/library/net/http/http/request_put_spec.rb b/spec/ruby/library/net/http/http/request_put_spec.rb
deleted file mode 100644
index 987b52ceb0..0000000000
--- a/spec/ruby/library/net/http/http/request_put_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/request_put'
-
-describe "Net::HTTP#request_put" do
-  it_behaves_like :net_ftp_request_put, :request_put
-end
diff --git a/spec/ruby/library/net/http/http/request_spec.rb b/spec/ruby/library/net/http/http/request_spec.rb
deleted file mode 100644
index e63dde9c8d..0000000000
--- a/spec/ruby/library/net/http/http/request_spec.rb
+++ /dev/null
@@ -1,109 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#request" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed request_object" do
-    it "makes a HTTP Request based on the passed request_object" do
-      response = @http.request(Net::HTTP::Get.new("/request"), "test=test")
-      response.body.should == "Request type: GET"
-
-      response = @http.request(Net::HTTP::Head.new("/request"), "test=test")
-      response.body.should be_nil
-
-      response = @http.request(Net::HTTP::Post.new("/request"), "test=test")
-      response.body.should == "Request type: POST"
-
-      response = @http.request(Net::HTTP::Put.new("/request"), "test=test")
-      response.body.should == "Request type: PUT"
-
-      response = @http.request(Net::HTTP::Proppatch.new("/request"), "test=test")
-      response.body.should == "Request type: PROPPATCH"
-
-      response = @http.request(Net::HTTP::Lock.new("/request"), "test=test")
-      response.body.should == "Request type: LOCK"
-
-      response = @http.request(Net::HTTP::Unlock.new("/request"), "test=test")
-      response.body.should == "Request type: UNLOCK"
-
-      # TODO: Does not work?
-      #response = @http.request(Net::HTTP::Options.new("/request"), "test=test")
-      #response.body.should be_nil
-
-      response = @http.request(Net::HTTP::Propfind.new("/request"), "test=test")
-      response.body.should == "Request type: PROPFIND"
-
-      response = @http.request(Net::HTTP::Delete.new("/request"), "test=test")
-      response.body.should == "Request type: DELETE"
-
-      response = @http.request(Net::HTTP::Move.new("/request"), "test=test")
-      response.body.should == "Request type: MOVE"
-
-      response = @http.request(Net::HTTP::Copy.new("/request"), "test=test")
-      response.body.should == "Request type: COPY"
-
-      response = @http.request(Net::HTTP::Mkcol.new("/request"), "test=test")
-      response.body.should == "Request type: MKCOL"
-
-      response = @http.request(Net::HTTP::Trace.new("/request"), "test=test")
-      response.body.should == "Request type: TRACE"
-    end
-  end
-
-  describe "when passed request_object and request_body" do
-    it "sends the passed request_body when making the HTTP Request" do
-      response = @http.request(Net::HTTP::Get.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Head.new("/request/body"), "test=test")
-      response.body.should be_nil
-
-      response = @http.request(Net::HTTP::Post.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Put.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Proppatch.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Lock.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Unlock.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      # TODO: Does not work?
-      #response = @http.request(Net::HTTP::Options.new("/request/body"), "test=test")
-      #response.body.should be_nil
-
-      response = @http.request(Net::HTTP::Propfind.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Delete.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Move.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Copy.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Mkcol.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-
-      response = @http.request(Net::HTTP::Trace.new("/request/body"), "test=test")
-      response.body.should == "test=test"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/request_types_spec.rb b/spec/ruby/library/net/http/http/request_types_spec.rb
deleted file mode 100644
index 99d754d3d1..0000000000
--- a/spec/ruby/library/net/http/http/request_types_spec.rb
+++ /dev/null
@@ -1,254 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP::Get" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Get.should < Net::HTTPRequest
-  end
-
-  it "represents the 'GET'-Request-Method" do
-    Net::HTTP::Get::METHOD.should == "GET"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Get::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Get::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Head" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Head.should < Net::HTTPRequest
-  end
-
-  it "represents the 'HEAD'-Request-Method" do
-    Net::HTTP::Head::METHOD.should == "HEAD"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Head::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has no Response Body" do
-    Net::HTTP::Head::RESPONSE_HAS_BODY.should be_false
-  end
-end
-
-describe "Net::HTTP::Post" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Post.should < Net::HTTPRequest
-  end
-
-  it "represents the 'POST'-Request-Method" do
-    Net::HTTP::Post::METHOD.should == "POST"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Post::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Post::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Put" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Put.should < Net::HTTPRequest
-  end
-
-  it "represents the 'PUT'-Request-Method" do
-    Net::HTTP::Put::METHOD.should == "PUT"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Put::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Put::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Delete" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Delete.should < Net::HTTPRequest
-  end
-
-  it "represents the 'DELETE'-Request-Method" do
-    Net::HTTP::Delete::METHOD.should == "DELETE"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Delete::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Delete::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Options" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Options.should < Net::HTTPRequest
-  end
-
-  it "represents the 'OPTIONS'-Request-Method" do
-    Net::HTTP::Options::METHOD.should == "OPTIONS"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Options::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has no Response Body" do
-    Net::HTTP::Options::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Trace" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Trace.should < Net::HTTPRequest
-  end
-
-  it "represents the 'TRACE'-Request-Method" do
-    Net::HTTP::Trace::METHOD.should == "TRACE"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Trace::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Trace::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Propfind" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Propfind.should < Net::HTTPRequest
-  end
-
-  it "represents the 'PROPFIND'-Request-Method" do
-    Net::HTTP::Propfind::METHOD.should == "PROPFIND"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Propfind::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Propfind::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Proppatch" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Proppatch.should < Net::HTTPRequest
-  end
-
-  it "represents the 'PROPPATCH'-Request-Method" do
-    Net::HTTP::Proppatch::METHOD.should == "PROPPATCH"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Proppatch::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Proppatch::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Mkcol" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Mkcol.should < Net::HTTPRequest
-  end
-
-  it "represents the 'MKCOL'-Request-Method" do
-    Net::HTTP::Mkcol::METHOD.should == "MKCOL"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Mkcol::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Mkcol::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Copy" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Copy.should < Net::HTTPRequest
-  end
-
-  it "represents the 'COPY'-Request-Method" do
-    Net::HTTP::Copy::METHOD.should == "COPY"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Copy::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Copy::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Move" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Move.should < Net::HTTPRequest
-  end
-
-  it "represents the 'MOVE'-Request-Method" do
-    Net::HTTP::Move::METHOD.should == "MOVE"
-  end
-
-  it "has no Request Body" do
-    Net::HTTP::Move::REQUEST_HAS_BODY.should be_false
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Move::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Lock" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Lock.should < Net::HTTPRequest
-  end
-
-  it "represents the 'LOCK'-Request-Method" do
-    Net::HTTP::Lock::METHOD.should == "LOCK"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Lock::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Lock::RESPONSE_HAS_BODY.should be_true
-  end
-end
-
-describe "Net::HTTP::Unlock" do
-  it "is a subclass of Net::HTTPRequest" do
-    Net::HTTP::Unlock.should < Net::HTTPRequest
-  end
-
-  it "represents the 'UNLOCK'-Request-Method" do
-    Net::HTTP::Unlock::METHOD.should == "UNLOCK"
-  end
-
-  it "has a Request Body" do
-    Net::HTTP::Unlock::REQUEST_HAS_BODY.should be_true
-  end
-
-  it "has a Response Body" do
-    Net::HTTP::Unlock::RESPONSE_HAS_BODY.should be_true
-  end
-end
diff --git a/spec/ruby/library/net/http/http/send_request_spec.rb b/spec/ruby/library/net/http/http/send_request_spec.rb
deleted file mode 100644
index 03fd32e470..0000000000
--- a/spec/ruby/library/net/http/http/send_request_spec.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#send_request" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-
-    # HEAD is special so handled separately
-    @methods = %w[
-      GET POST PUT DELETE
-      OPTIONS
-      PROPFIND PROPPATCH LOCK UNLOCK
-    ]
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  # TODO: Does only work with GET and POST requests
-  describe "when passed type, path" do
-    it "sends a HTTP Request of the passed type to the passed path" do
-      response = @http.send_request("HEAD", "/request")
-      response.body.should be_nil
-
-      @methods.each do |method|
-        response = @http.send_request(method, "/request")
-        response.body.should == "Request type: #{method}"
-      end
-    end
-  end
-
-  describe "when passed type, path, body" do
-    it "sends a HTTP Request with the passed body" do
-      response = @http.send_request("HEAD", "/request/body", "test=test")
-      response.body.should be_nil
-
-      @methods.each do |method|
-        response = @http.send_request(method, "/request/body", "test=test")
-        response.body.should == "test=test"
-      end
-    end
-  end
-
-  describe "when passed type, path, body, headers" do
-    it "sends a HTTP Request with the passed headers" do
-      referer = 'https://www.ruby-lang.org/'.freeze
-
-      response = @http.send_request("HEAD", "/request/header", "test=test", "referer" => referer)
-      response.body.should be_nil
-
-      @methods.each do |method|
-        response = @http.send_request(method, "/request/header", "test=test", "referer" => referer)
-        response.body.should include('"referer"=>["' + referer + '"]')
-      end
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/set_debug_output_spec.rb b/spec/ruby/library/net/http/http/set_debug_output_spec.rb
deleted file mode 100644
index 94b6f4499d..0000000000
--- a/spec/ruby/library/net/http/http/set_debug_output_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#set_debug_output when passed io" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sets the passed io as output stream for debugging" do
-    io = StringIO.new
-
-    @http.set_debug_output(io)
-    @http.start
-    io.string.should_not be_empty
-    size = io.string.size
-
-    @http.get("/")
-    io.string.size.should > size
-  end
-
-  it "outputs a warning when the connection has already been started" do
-    @http.start
-    -> { @http.set_debug_output(StringIO.new) }.should complain(/Net::HTTP#set_debug_output called after HTTP started/)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/request_get.rb b/spec/ruby/library/net/http/http/shared/request_get.rb
deleted file mode 100644
index b0eca665d6..0000000000
--- a/spec/ruby/library/net/http/http/shared/request_get.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-describe :net_ftp_request_get, shared: true do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed no block" do
-    it "sends a GET request to the passed path and returns the response" do
-      response = @http.send(@method, "/request")
-      response.body.should == "Request type: GET"
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request")
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-
-  describe "when passed a block" do
-    it "sends a GET request to the passed path and returns the response" do
-      response = @http.send(@method, "/request") {}
-      response.body.should == "Request type: GET"
-    end
-
-    it "yields the response to the passed block" do
-      @http.send(@method, "/request") do |response|
-        response.body.should == "Request type: GET"
-      end
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request") {}
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/request_head.rb b/spec/ruby/library/net/http/http/shared/request_head.rb
deleted file mode 100644
index 0e669de9ac..0000000000
--- a/spec/ruby/library/net/http/http/shared/request_head.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-describe :net_ftp_request_head, shared: true do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed no block" do
-    it "sends a head request to the passed path and returns the response" do
-      response = @http.send(@method, "/request")
-      response.body.should be_nil
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request")
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-
-  describe "when passed a block" do
-    it "sends a head request to the passed path and returns the response" do
-      response = @http.send(@method, "/request") {}
-      response.body.should be_nil
-    end
-
-    it "yields the response to the passed block" do
-      @http.send(@method, "/request") do |response|
-        response.body.should be_nil
-      end
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request") {}
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/request_post.rb b/spec/ruby/library/net/http/http/shared/request_post.rb
deleted file mode 100644
index 06c5e139f9..0000000000
--- a/spec/ruby/library/net/http/http/shared/request_post.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-describe :net_ftp_request_post, shared: true do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed no block" do
-    it "sends a post request to the passed path and returns the response" do
-      response = @http.send(@method, "/request", "test=test")
-      response.body.should == "Request type: POST"
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request", "test=test")
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-
-  describe "when passed a block" do
-    it "sends a post request to the passed path and returns the response" do
-      response = @http.send(@method, "/request", "test=test") {}
-      response.body.should == "Request type: POST"
-    end
-
-    it "yields the response to the passed block" do
-      @http.send(@method, "/request", "test=test") do |response|
-        response.body.should == "Request type: POST"
-      end
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request", "test=test") {}
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/request_put.rb b/spec/ruby/library/net/http/http/shared/request_put.rb
deleted file mode 100644
index 6ae791d7e7..0000000000
--- a/spec/ruby/library/net/http/http/shared/request_put.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-describe :net_ftp_request_put, shared: true do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when passed no block" do
-    it "sends a put request to the passed path and returns the response" do
-      response = @http.send(@method, "/request", "test=test")
-      response.body.should == "Request type: PUT"
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request", "test=test")
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-
-  describe "when passed a block" do
-    it "sends a put request to the passed path and returns the response" do
-      response = @http.send(@method, "/request", "test=test") {}
-      response.body.should == "Request type: PUT"
-    end
-
-    it "yields the response to the passed block" do
-      @http.send(@method, "/request", "test=test") do |response|
-        response.body.should == "Request type: PUT"
-      end
-    end
-
-    it "returns a Net::HTTPResponse object" do
-      response = @http.send(@method, "/request", "test=test") {}
-      response.should be_kind_of(Net::HTTPResponse)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/started.rb b/spec/ruby/library/net/http/http/shared/started.rb
deleted file mode 100644
index 9ff6272c31..0000000000
--- a/spec/ruby/library/net/http/http/shared/started.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-describe :net_http_started_p, shared: true do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "returns true when self has been started" do
-    @http.start
-    @http.send(@method).should be_true
-  end
-
-  it "returns false when self has not been started yet" do
-    @http.send(@method).should be_false
-  end
-
-  it "returns false when self has been stopped again" do
-    @http.start
-    @http.finish
-    @http.send(@method).should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/version_1_1.rb b/spec/ruby/library/net/http/http/shared/version_1_1.rb
deleted file mode 100644
index db3d6a986d..0000000000
--- a/spec/ruby/library/net/http/http/shared/version_1_1.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-describe :net_http_version_1_1_p, shared: true do
-  it "returns the state of net/http 1.1 features" do
-    Net::HTTP.version_1_2
-    Net::HTTP.send(@method).should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/http/shared/version_1_2.rb b/spec/ruby/library/net/http/http/shared/version_1_2.rb
deleted file mode 100644
index b044182c60..0000000000
--- a/spec/ruby/library/net/http/http/shared/version_1_2.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-describe :net_http_version_1_2_p, shared: true do
-  it "returns the state of net/http 1.2 features" do
-    Net::HTTP.version_1_2
-    Net::HTTP.send(@method).should be_true
-  end
-end
diff --git a/spec/ruby/library/net/http/http/socket_type_spec.rb b/spec/ruby/library/net/http/http/socket_type_spec.rb
deleted file mode 100644
index 5c844ddf94..0000000000
--- a/spec/ruby/library/net/http/http/socket_type_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP.socket_type" do
-  it "returns BufferedIO" do
-    Net::HTTP.socket_type.should == Net::BufferedIO
-  end
-end
diff --git a/spec/ruby/library/net/http/http/start_spec.rb b/spec/ruby/library/net/http/http/start_spec.rb
deleted file mode 100644
index a2768eed18..0000000000
--- a/spec/ruby/library/net/http/http/start_spec.rb
+++ /dev/null
@@ -1,111 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP.start" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @port = NetHTTPSpecs.port
-  end
-
-  after :each do
-    NetHTTPSpecs.stop_server
-  end
-
-  describe "when not passed a block" do
-    before :each do
-      @http = Net::HTTP.start("localhost", @port)
-    end
-
-    after :each do
-      @http.finish if @http.started?
-    end
-
-    it "returns a new Net::HTTP object for the passed address and port" do
-      @http.should be_kind_of(Net::HTTP)
-      @http.address.should == "localhost"
-      @http.port.should == @port
-    end
-
-    it "opens the tcp connection" do
-      @http.started?.should be_true
-    end
-  end
-
-  describe "when passed a block" do
-    it "returns the blocks return value" do
-      Net::HTTP.start("localhost", @port) { :test }.should == :test
-    end
-
-    it "yields the new Net::HTTP object to the block" do
-      yielded = false
-      Net::HTTP.start("localhost", @port) do |net|
-        yielded = true
-        net.should be_kind_of(Net::HTTP)
-      end
-      yielded.should be_true
-    end
-
-    it "opens the tcp connection before yielding" do
-      Net::HTTP.start("localhost", @port) { |http| http.started?.should be_true }
-    end
-
-    it "closes the tcp connection after yielding" do
-      net = nil
-      Net::HTTP.start("localhost", @port) { |x| net = x }
-      net.started?.should be_false
-    end
-  end
-end
-
-describe "Net::HTTP#start" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.new("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "returns self" do
-    @http.start.should equal(@http)
-  end
-
-  it "opens the tcp connection" do
-    @http.start
-    @http.started?.should be_true
-  end
-
-  describe "when self has already been started" do
-    it "raises an IOError" do
-      @http.start
-      -> { @http.start }.should raise_error(IOError)
-    end
-  end
-
-  describe "when passed a block" do
-    it "returns the blocks return value" do
-      @http.start { :test }.should == :test
-    end
-
-    it "yields the new Net::HTTP object to the block" do
-      yielded = false
-      @http.start do |http|
-        yielded = true
-        http.should equal(@http)
-      end
-      yielded.should be_true
-    end
-
-    it "opens the tcp connection before yielding" do
-      @http.start { |http| http.started?.should be_true }
-    end
-
-    it "closes the tcp connection after yielding" do
-      @http.start { }
-      @http.started?.should be_false
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/http/started_spec.rb b/spec/ruby/library/net/http/http/started_spec.rb
deleted file mode 100644
index ea441ed16a..0000000000
--- a/spec/ruby/library/net/http/http/started_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-require_relative 'shared/started'
-
-describe "Net::HTTP#started?" do
-  it_behaves_like :net_http_started_p, :started?
-end
diff --git a/spec/ruby/library/net/http/http/trace_spec.rb b/spec/ruby/library/net/http/http/trace_spec.rb
deleted file mode 100644
index 94a1bf6655..0000000000
--- a/spec/ruby/library/net/http/http/trace_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#trace" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends a TRACE request to the passed path and returns the response" do
-    response = @http.trace("/request")
-    response.body.should == "Request type: TRACE"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.trace("/request").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/unlock_spec.rb b/spec/ruby/library/net/http/http/unlock_spec.rb
deleted file mode 100644
index a4f1b7a1d1..0000000000
--- a/spec/ruby/library/net/http/http/unlock_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/http_server'
-
-describe "Net::HTTP#unlock" do
-  before :each do
-    NetHTTPSpecs.start_server
-    @http = Net::HTTP.start("localhost", NetHTTPSpecs.port)
-  end
-
-  after :each do
-    @http.finish if @http.started?
-    NetHTTPSpecs.stop_server
-  end
-
-  it "sends an UNLOCK request to the passed path and returns the response" do
-    response = @http.unlock("/request", "test=test")
-    response.body.should == "Request type: UNLOCK"
-  end
-
-  it "returns a Net::HTTPResponse" do
-    @http.unlock("/request", "test=test").should be_kind_of(Net::HTTPResponse)
-  end
-end
diff --git a/spec/ruby/library/net/http/http/use_ssl_spec.rb b/spec/ruby/library/net/http/http/use_ssl_spec.rb
deleted file mode 100644
index be1ec7fa25..0000000000
--- a/spec/ruby/library/net/http/http/use_ssl_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTP#use_ssl?" do
-  it "returns false" do
-    http = Net::HTTP.new("localhost")
-    http.use_ssl?.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/http/version_1_1_spec.rb b/spec/ruby/library/net/http/http/version_1_1_spec.rb
deleted file mode 100644
index 1c069e9ea6..0000000000
--- a/spec/ruby/library/net/http/http/version_1_1_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/version_1_1'
-
-describe "Net::HTTP.version_1_1?" do
-  it_behaves_like :net_http_version_1_1_p, :version_1_1?
-end
diff --git a/spec/ruby/library/net/http/http/version_1_2_spec.rb b/spec/ruby/library/net/http/http/version_1_2_spec.rb
deleted file mode 100644
index 4e601462c9..0000000000
--- a/spec/ruby/library/net/http/http/version_1_2_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/version_1_2'
-
-describe "Net::HTTP.version_1_2" do
-  it "turns on net/http 1.2 features" do
-    Net::HTTP.version_1_2
-
-    Net::HTTP.version_1_2?.should be_true
-    Net::HTTP.version_1_1?.should be_false
-  end
-
-  it "returns true" do
-    Net::HTTP.version_1_2.should be_true
-  end
-end
-
-describe "Net::HTTP.version_1_2?" do
-  it_behaves_like :net_http_version_1_2_p, :version_1_2?
-end
diff --git a/spec/ruby/library/net/http/httpexceptions/initialize_spec.rb b/spec/ruby/library/net/http/httpexceptions/initialize_spec.rb
deleted file mode 100644
index 8e3fd8cc02..0000000000
--- a/spec/ruby/library/net/http/httpexceptions/initialize_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPExceptions#initialize when passed message, response" do
-  before :each do
-    @exception = NetHTTPExceptionsSpecs::Simple.new("error message", "a http response")
-  end
-
-  it "calls super with the passed message" do
-    @exception.message.should == "error message"
-  end
-
-  it "sets self's response to the passed response" do
-    @exception.response.should == "a http response"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpexceptions/response_spec.rb b/spec/ruby/library/net/http/httpexceptions/response_spec.rb
deleted file mode 100644
index 205b2bc212..0000000000
--- a/spec/ruby/library/net/http/httpexceptions/response_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPExceptions#response" do
-  it "returns self's response" do
-    exception = NetHTTPExceptionsSpecs::Simple.new("error message", "a http response")
-    exception.response.should == "a http response"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/body_exist_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/body_exist_spec.rb
deleted file mode 100644
index 7d081939b8..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/body_exist_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#body_exist?" do
-  it "returns true when the response is expected to have a body" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.body_exist?.should be_true
-
-    request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
-    request.body_exist?.should be_false
-  end
-
-  describe "when $VERBOSE is true" do
-    it "emits a warning" do
-      request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
-      -> {
-        request.body_exist?
-      }.should complain(/body_exist\? is obsolete/, verbose: true)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/body_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/body_spec.rb
deleted file mode 100644
index a215895b57..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/body_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-
-describe "Net::HTTPGenericRequest#body" do
-  it "returns self's request body" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.body.should be_nil
-
-    request.body = "Some Content"
-    request.body.should == "Some Content"
-  end
-end
-
-describe "Net::HTTPGenericRequest#body=" do
-  before :each do
-    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-  end
-
-  it "sets self's body content to the passed String" do
-    @request.body = "Some Content"
-    @request.body.should == "Some Content"
-  end
-
-  it "sets self's body stream to nil" do
-    @request.body_stream = StringIO.new("")
-    @request.body = "Some Content"
-    @request.body_stream.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/body_stream_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/body_stream_spec.rb
deleted file mode 100644
index c2a60e6836..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/body_stream_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-
-describe "Net::HTTPGenericRequest#body_stream" do
-  it "returns self's body stream Object" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.body_stream.should be_nil
-
-    stream = StringIO.new("test")
-    request.body_stream = stream
-    request.body_stream.should equal(stream)
-  end
-end
-
-describe "Net::HTTPGenericRequest#body_stream=" do
-  before :each do
-    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    @stream = StringIO.new("test")
-  end
-
-  it "sets self's body stream to the passed Object" do
-    @request.body_stream = @stream
-    @request.body_stream.should equal(@stream)
-  end
-
-  it "sets self's body to nil" do
-    @request.body = "Some Content"
-    @request.body_stream = @stream
-    @request.body.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/exec_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/exec_spec.rb
deleted file mode 100644
index da5b1a63be..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/exec_spec.rb
+++ /dev/null
@@ -1,131 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-
-describe "Net::HTTPGenericRequest#exec when passed socket, version, path" do
-  before :each do
-    @socket = StringIO.new("")
-    @buffered_socket = Net::BufferedIO.new(@socket)
-  end
-
-  it "executes the request over the socket to the path using the HTTP version" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-
-    request.exec(@buffered_socket, "1.1", "/some/path")
-    str = @socket.string
-
-    str.should =~ %r[POST /some/path HTTP/1.1\r\n]
-    str.should =~ %r[Accept: \*/\*\r\n]
-    str[-4..-1].should == "\r\n\r\n"
-
-    request = Net::HTTPGenericRequest.new("GET", true, true, "/some/path",
-                                          "Content-Type" => "text/html")
-
-    request.exec(@buffered_socket, "1.0", "/some/other/path")
-    str = @socket.string
-
-    str.should =~ %r[GET /some/other/path HTTP/1.0\r\n]
-    str.should =~ %r[Accept: \*/\*\r\n]
-    str.should =~ %r[Content-Type: text/html\r\n]
-    str[-4..-1].should == "\r\n\r\n"
-  end
-
-  describe "when a request body is set" do
-    it "sets the 'Content-Type' header to 'application/x-www-form-urlencoded' unless the 'Content-Type' header is supplied" do
-      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-      request.body = "Some Content"
-
-      request.exec(@buffered_socket, "1.1", "/some/other/path")
-      str = @socket.string
-
-      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
-      str.should =~ %r[Accept: \*/\*\r\n]
-      str.should =~ %r[Content-Type: application/x-www-form-urlencoded\r\n]
-      str.should =~ %r[Content-Length: 12\r\n]
-      str[-16..-1].should == "\r\n\r\nSome Content"
-    end
-
-    it "correctly sets the 'Content-Length' header and includes the body" do
-      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
-                                            "Content-Type" => "text/html")
-      request.body = "Some Content"
-
-      request.exec(@buffered_socket, "1.1", "/some/other/path")
-      str = @socket.string
-
-      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
-      str.should =~ %r[Accept: \*/\*\r\n]
-      str.should =~ %r[Content-Type: text/html\r\n]
-      str.should =~ %r[Content-Length: 12\r\n]
-      str[-16..-1].should == "\r\n\r\nSome Content"
-    end
-  end
-
-  describe "when a body stream is set" do
-    it "sets the 'Content-Type' header to 'application/x-www-form-urlencoded' unless the 'Content-Type' header is supplied" do
-      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
-                                            "Content-Length" => "10")
-      request.body_stream = StringIO.new("a" * 20)
-
-      request.exec(@buffered_socket, "1.1", "/some/other/path")
-      str = @socket.string
-
-      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
-      str.should =~ %r[Accept: \*/\*\r\n]
-      str.should =~ %r[Content-Type: application/x-www-form-urlencoded\r\n]
-      str.should =~ %r[Content-Length: 10\r\n]
-      str[-24..-1].should == "\r\n\r\naaaaaaaaaaaaaaaaaaaa"
-    end
-
-    it "sends the whole stream, regardless of the 'Content-Length' header" do
-      request = Net::HTTPGenericRequest.new("POST", true, true,"/some/path",
-                                            "Content-Type" => "text/html",
-                                            "Content-Length" => "10")
-      request.body_stream = StringIO.new("a" * 20)
-
-      request.exec(@buffered_socket, "1.1", "/some/other/path")
-      str = @socket.string
-
-      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
-      str.should =~ %r[Accept: \*/\*\r\n]
-      str.should =~ %r[Content-Type: text/html\r\n]
-      str.should =~ %r[Content-Length: 10\r\n]
-      str[-24..-1].should == "\r\n\r\naaaaaaaaaaaaaaaaaaaa"
-    end
-
-    it "sends the request in chunks when 'Transfer-Encoding' is set to 'chunked'" do
-      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
-                                            "Content-Type" => "text/html",
-                                            "Transfer-Encoding" => "chunked")
-      datasize = 1024 * 10
-      request.body_stream = StringIO.new("a" * datasize)
-
-      request.exec(@buffered_socket, "1.1", "/some/other/path")
-      str = @socket.string
-
-      str.should =~ %r[POST /some/other/path HTTP/1.1\r\n]
-      str.should =~ %r[Accept: \*/\*\r\n]
-      str.should =~ %r[Content-Type: text/html\r\n]
-      str.should =~ %r[Transfer-Encoding: chunked\r\n]
-      str =~ %r[\r\n\r\n]
-      str = $'
-      while datasize > 0
-        chunk_size_line, str = str.split(/\r\n/, 2)
-        chunk_size = chunk_size_line[/\A[0-9A-Fa-f]+/].to_i(16)
-        str.slice!(0, chunk_size).should == 'a' * chunk_size
-        datasize -= chunk_size
-        str.slice!(0, 2).should == "\r\n"
-      end
-      datasize.should == 0
-      str.should == %"0\r\n\r\n"
-    end
-
-    it "raises an ArgumentError when the 'Content-Length' is not set or 'Transfer-Encoding' is not set to 'chunked'" do
-      request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path",
-                                            "Content-Type" => "text/html")
-      request.body_stream = StringIO.new("Some Content")
-
-      -> { request.exec(@buffered_socket, "1.1", "/some/other/path") }.should raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/inspect_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/inspect_spec.rb
deleted file mode 100644
index 36240949c3..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/inspect_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#inspect" do
-  it "returns a String representation of self" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.inspect.should == "#<Net::HTTPGenericRequest POST>"
-
-    request = Net::HTTPGenericRequest.new("GET", false, true, "/some/path")
-    request.inspect.should == "#<Net::HTTPGenericRequest GET>"
-
-    request = Net::HTTPGenericRequest.new("BLA", true, true, "/some/path")
-    request.inspect.should == "#<Net::HTTPGenericRequest BLA>"
-
-    # Subclasses
-    request = Net::HTTP::Get.new("/some/path")
-    request.inspect.should == "#<Net::HTTP::Get GET>"
-
-    request = Net::HTTP::Post.new("/some/path")
-    request.inspect.should == "#<Net::HTTP::Post POST>"
-
-    request = Net::HTTP::Trace.new("/some/path")
-    request.inspect.should == "#<Net::HTTP::Trace TRACE>"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/method_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/method_spec.rb
deleted file mode 100644
index 3f7c2cbf2b..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/method_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#method" do
-  it "returns self's request method" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.method.should == "POST"
-
-    request = Net::HTTPGenericRequest.new("GET", false, true, "/some/path")
-    request.method.should == "GET"
-
-    request = Net::HTTPGenericRequest.new("BLA", true, true, "/some/path")
-    request.method.should == "BLA"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/path_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/path_spec.rb
deleted file mode 100644
index fc4cf9af53..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/path_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#path" do
-  it "returns self's request path" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.path.should == "/some/path"
-
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/other/path")
-    request.path.should == "/some/other/path"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/request_body_permitted_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/request_body_permitted_spec.rb
deleted file mode 100644
index 50cd1ff637..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/request_body_permitted_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#request_body_permitted?" do
-  it "returns true when the request is expected to have a body" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.request_body_permitted?.should be_true
-
-    request = Net::HTTPGenericRequest.new("POST", false, true, "/some/path")
-    request.request_body_permitted?.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/response_body_permitted_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/response_body_permitted_spec.rb
deleted file mode 100644
index 0c4165d0ab..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/response_body_permitted_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#response_body_permitted?" do
-  it "returns true when the response is expected to have a body" do
-    request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-    request.response_body_permitted?.should be_true
-
-    request = Net::HTTPGenericRequest.new("POST", true, false, "/some/path")
-    request.response_body_permitted?.should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/httpgenericrequest/set_body_internal_spec.rb b/spec/ruby/library/net/http/httpgenericrequest/set_body_internal_spec.rb
deleted file mode 100644
index 7494c69173..0000000000
--- a/spec/ruby/library/net/http/httpgenericrequest/set_body_internal_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPGenericRequest#set_body_internal when passed string" do
-  before :each do
-    @request = Net::HTTPGenericRequest.new("POST", true, true, "/some/path")
-  end
-
-  it "sets self's body to the passed string" do
-    @request.set_body_internal("Some Content")
-    @request.body.should == "Some Content"
-  end
-
-  it "raises an ArgumentError when the body or body_stream of self have already been set" do
-    @request.body = "Some Content"
-    -> { @request.set_body_internal("Some other Content") }.should raise_error(ArgumentError)
-
-    @request.body_stream = "Some Content"
-    -> { @request.set_body_internal("Some other Content") }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/add_field_spec.rb b/spec/ruby/library/net/http/httpheader/add_field_spec.rb
deleted file mode 100644
index 882d5ac5bb..0000000000
--- a/spec/ruby/library/net/http/httpheader/add_field_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#add_field when passed key, value" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "adds the passed value to the header entry with the passed key" do
-    @headers.add_field("My-Header", "a")
-    @headers.get_fields("My-Header").should == ["a"]
-
-    @headers.add_field("My-Header", "b")
-    @headers.get_fields("My-Header").should == ["a", "b"]
-
-    @headers.add_field("My-Header", "c")
-    @headers.get_fields("My-Header").should == ["a", "b", "c"]
-  end
-
-  it "is case-insensitive" do
-    @headers.add_field("My-Header", "a")
-    @headers.get_fields("My-Header").should == ["a"]
-
-    @headers.add_field("my-header", "b")
-    @headers.get_fields("My-Header").should == ["a", "b"]
-
-    @headers.add_field("MY-HEADER", "c")
-    @headers.get_fields("My-Header").should == ["a", "b", "c"]
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/basic_auth_spec.rb b/spec/ruby/library/net/http/httpheader/basic_auth_spec.rb
deleted file mode 100644
index fa2a710fe1..0000000000
--- a/spec/ruby/library/net/http/httpheader/basic_auth_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#basic_auth when passed account, password" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "sets the 'Authorization' Header entry for basic authorization" do
-    @headers.basic_auth("rubyspec", "rocks")
-    @headers["Authorization"].should == "Basic cnVieXNwZWM6cm9ja3M="
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/canonical_each_spec.rb b/spec/ruby/library/net/http/httpheader/canonical_each_spec.rb
deleted file mode 100644
index 0dddd3049b..0000000000
--- a/spec/ruby/library/net/http/httpheader/canonical_each_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_capitalized'
-
-describe "Net::HTTPHeader#canonical_each" do
-  it_behaves_like :net_httpheader_each_capitalized, :canonical_each
-end
diff --git a/spec/ruby/library/net/http/httpheader/chunked_spec.rb b/spec/ruby/library/net/http/httpheader/chunked_spec.rb
deleted file mode 100644
index 96b758981b..0000000000
--- a/spec/ruby/library/net/http/httpheader/chunked_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#chunked?" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns true if the 'Transfer-Encoding' header entry is set to chunked" do
-    @headers.chunked?.should be_false
-
-    @headers["Transfer-Encoding"] = "bla"
-    @headers.chunked?.should be_false
-
-    @headers["Transfer-Encoding"] = "blachunkedbla"
-    @headers.chunked?.should be_false
-
-    @headers["Transfer-Encoding"] = "chunked"
-    @headers.chunked?.should be_true
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/content_length_spec.rb b/spec/ruby/library/net/http/httpheader/content_length_spec.rb
deleted file mode 100644
index e344817e82..0000000000
--- a/spec/ruby/library/net/http/httpheader/content_length_spec.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#content_length" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns nil if no 'Content-Length' header entry is set" do
-    @headers.content_length.should be_nil
-  end
-
-  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Length' header entry has an invalid format" do
-    @headers["Content-Length"] = "invalid"
-    -> { @headers.content_length }.should raise_error(Net::HTTPHeaderSyntaxError)
-  end
-
-  it "returns the value of the 'Content-Length' header entry as an Integer" do
-    @headers["Content-Length"] = "123"
-    @headers.content_length.should eql(123)
-
-    @headers["Content-Length"] = "123valid"
-    @headers.content_length.should eql(123)
-
-    @headers["Content-Length"] = "valid123"
-    @headers.content_length.should eql(123)
-  end
-end
-
-describe "Net::HTTPHeader#content_length=" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "removes the 'Content-Length' entry if passed false or nil" do
-    @headers["Content-Length"] = "123"
-    @headers.content_length = nil
-    @headers["Content-Length"].should be_nil
-  end
-
-  it "sets the 'Content-Length' entry to the passed value" do
-    @headers.content_length = "123"
-    @headers["Content-Length"].should == "123"
-
-    @headers.content_length = "123valid"
-    @headers["Content-Length"].should == "123"
-  end
-
-  it "sets the 'Content-Length' entry to 0 if the passed value is not valid" do
-    @headers.content_length = "invalid123"
-    @headers["Content-Length"].should == "0"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/content_range_spec.rb b/spec/ruby/library/net/http/httpheader/content_range_spec.rb
deleted file mode 100644
index ba75f9a9a1..0000000000
--- a/spec/ruby/library/net/http/httpheader/content_range_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#content_range" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns a Range object that represents the 'Content-Range' header entry" do
-    @headers["Content-Range"] = "bytes 0-499/1234"
-    @headers.content_range.should == (0..499)
-
-    @headers["Content-Range"] = "bytes 500-1233/1234"
-    @headers.content_range.should == (500..1233)
-  end
-
-  it "returns nil when there is no 'Content-Range' header entry" do
-    @headers.content_range.should be_nil
-  end
-
-  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Range' has an invalid format" do
-    @headers["Content-Range"] = "invalid"
-    -> { @headers.content_range }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Content-Range"] = "bytes 123-abc"
-    -> { @headers.content_range }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Content-Range"] = "bytes abc-123"
-    -> { @headers.content_range }.should raise_error(Net::HTTPHeaderSyntaxError)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/content_type_spec.rb b/spec/ruby/library/net/http/httpheader/content_type_spec.rb
deleted file mode 100644
index 1f8b4ba326..0000000000
--- a/spec/ruby/library/net/http/httpheader/content_type_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_content_type'
-
-describe "Net::HTTPHeader#content_type" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the content type string, as per 'Content-Type' header entry" do
-    @headers["Content-Type"] = "text/html"
-    @headers.content_type.should == "text/html"
-
-    @headers["Content-Type"] = "text/html;charset=utf-8"
-    @headers.content_type.should == "text/html"
-  end
-
-  it "returns nil if the 'Content-Type' header entry does not exist" do
-    @headers.content_type.should be_nil
-  end
-end
-
-describe "Net::HTTPHeader#content_type=" do
-  it_behaves_like :net_httpheader_set_content_type, :content_type=
-end
diff --git a/spec/ruby/library/net/http/httpheader/delete_spec.rb b/spec/ruby/library/net/http/httpheader/delete_spec.rb
deleted file mode 100644
index 603ae198de..0000000000
--- a/spec/ruby/library/net/http/httpheader/delete_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#delete when passed key" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "removes the header entry with the passed key" do
-    @headers["My-Header"] = "test"
-    @headers.delete("My-Header")
-
-    @headers["My-Header"].should be_nil
-    @headers.size.should eql(0)
-  end
-
-  it "returns the removed values" do
-    @headers["My-Header"] = "test"
-    @headers.delete("My-Header").should == ["test"]
-  end
-
-  it "is case-insensitive" do
-    @headers["My-Header"] = "test"
-    @headers.delete("my-header")
-
-    @headers["My-Header"].should be_nil
-    @headers.size.should eql(0)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_capitalized_name_spec.rb b/spec/ruby/library/net/http/httpheader/each_capitalized_name_spec.rb
deleted file mode 100644
index 1af2c6939c..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_capitalized_name_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#each_capitalized_name" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-    @headers["My-Header"] = "test"
-    @headers.add_field("My-Other-Header", "a")
-    @headers.add_field("My-Other-Header", "b")
-  end
-
-  describe "when passed a block" do
-    it "yields each header key to the passed block (keys capitalized)" do
-      res = []
-      @headers.each_capitalized_name do |key|
-        res << key
-      end
-      res.sort.should == ["My-Header", "My-Other-Header"]
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Enumerator" do
-      enumerator = @headers.each_capitalized_name
-      enumerator.should be_an_instance_of(Enumerator)
-
-      res = []
-      enumerator.each do |key|
-        res << key
-      end
-      res.sort.should == ["My-Header", "My-Other-Header"]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_capitalized_spec.rb b/spec/ruby/library/net/http/httpheader/each_capitalized_spec.rb
deleted file mode 100644
index 961a2d051f..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_capitalized_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_capitalized'
-
-describe "Net::HTTPHeader#each_capitalized" do
-  it_behaves_like :net_httpheader_each_capitalized, :each_capitalized
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_header_spec.rb b/spec/ruby/library/net/http/httpheader/each_header_spec.rb
deleted file mode 100644
index 19634a001b..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_header_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_header'
-
-describe "Net::HTTPHeader#each_header" do
-  it_behaves_like :net_httpheader_each_header, :each_header
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_key_spec.rb b/spec/ruby/library/net/http/httpheader/each_key_spec.rb
deleted file mode 100644
index ebb17d2eac..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_key_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_name'
-
-describe "Net::HTTPHeader#each_key" do
-  it_behaves_like :net_httpheader_each_name, :each_key
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_name_spec.rb b/spec/ruby/library/net/http/httpheader/each_name_spec.rb
deleted file mode 100644
index f4533ebcfb..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_name_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_name'
-
-describe "Net::HTTPHeader#each_name" do
-  it_behaves_like :net_httpheader_each_name, :each_name
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_spec.rb b/spec/ruby/library/net/http/httpheader/each_spec.rb
deleted file mode 100644
index 7ba8434f75..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/each_header'
-
-describe "Net::HTTPHeader#each" do
-  it_behaves_like :net_httpheader_each_header, :each
-end
diff --git a/spec/ruby/library/net/http/httpheader/each_value_spec.rb b/spec/ruby/library/net/http/httpheader/each_value_spec.rb
deleted file mode 100644
index 3224de7703..0000000000
--- a/spec/ruby/library/net/http/httpheader/each_value_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#each_value" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-    @headers["My-Header"] = "test"
-    @headers.add_field("My-Other-Header", "a")
-    @headers.add_field("My-Other-Header", "b")
-  end
-
-  describe "when passed a block" do
-    it "yields each header entry's joined values" do
-      res = []
-      @headers.each_value do |value|
-        res << value
-      end
-      res.sort.should == ["a, b", "test"]
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Enumerator" do
-      enumerator = @headers.each_value
-      enumerator.should be_an_instance_of(Enumerator)
-
-      res = []
-      enumerator.each do |key|
-        res << key
-      end
-      res.sort.should == ["a, b", "test"]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/element_reference_spec.rb b/spec/ruby/library/net/http/httpheader/element_reference_spec.rb
deleted file mode 100644
index 4a35e20d20..0000000000
--- a/spec/ruby/library/net/http/httpheader/element_reference_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#[] when passed key" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the value of the header entry with the passed key" do
-    @headers["My-Header"] = "test"
-    @headers["My-Header"].should == "test"
-    @headers["My-Other-Header"] = "another test"
-    @headers["My-Other-Header"].should == "another test"
-  end
-
-  it "is case-insensitive" do
-    @headers["My-Header"] = "test"
-
-    @headers['My-Header'].should == "test"
-    @headers['my-Header'].should == "test"
-    @headers['My-header'].should == "test"
-    @headers['my-header'].should == "test"
-    @headers['MY-HEADER'].should == "test"
-  end
-
-  it "returns multi-element values joined together" do
-    @headers["My-Header"] = "test"
-    @headers.add_field("My-Header", "another test")
-    @headers.add_field("My-Header", "and one more")
-
-    @headers["My-Header"].should == "test, another test, and one more"
-  end
-
-  it "returns nil for non-existing entries" do
-    @headers["My-Header"].should be_nil
-    @headers["My-Other-Header"].should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/element_set_spec.rb b/spec/ruby/library/net/http/httpheader/element_set_spec.rb
deleted file mode 100644
index e9ad64fafc..0000000000
--- a/spec/ruby/library/net/http/httpheader/element_set_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#[]= when passed key, value" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "sets the header entry with the passed key to the passed value" do
-    @headers["My-Header"] = "test"
-    @headers["My-Header"].should == "test"
-
-    @headers["My-Header"] = "overwritten"
-    @headers["My-Header"].should == "overwritten"
-
-    @headers["My-Other-Header"] = "another test"
-    @headers["My-Other-Header"].should == "another test"
-  end
-
-  it "is case-insensitive" do
-    @headers['My-Header'] = "test"
-    @headers['my-Header'] = "another test"
-    @headers['My-header'] = "and one more test"
-    @headers['my-header'] = "and another one"
-    @headers['MY-HEADER'] = "last one"
-
-    @headers["My-Header"].should == "last one"
-    @headers.size.should eql(1)
-  end
-
-  it "removes the header entry with the passed key when the value is false or nil" do
-    @headers['My-Header'] = "test"
-    @headers['My-Header'] = nil
-    @headers['My-Header'].should be_nil
-
-    @headers['My-Header'] = "test"
-    @headers['My-Header'] = false
-    @headers['My-Header'].should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/fetch_spec.rb b/spec/ruby/library/net/http/httpheader/fetch_spec.rb
deleted file mode 100644
index ea15679acb..0000000000
--- a/spec/ruby/library/net/http/httpheader/fetch_spec.rb
+++ /dev/null
@@ -1,68 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#fetch" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  describe "when passed key" do
-    it "returns the header entry for the passed key" do
-      @headers["My-Header"] = "test"
-      @headers.fetch("My-Header").should == "test"
-
-      @headers.add_field("My-Other-Header", "a")
-      @headers.add_field("My-Other-Header", "b")
-      @headers.add_field("My-Other-Header", "c")
-      @headers.fetch("My-Other-Header").should == "a, b, c"
-    end
-
-    it "is case-insensitive" do
-      @headers["My-Header"] = "test"
-      @headers.fetch("my-header").should == "test"
-      @headers.fetch("MY-HEADER").should == "test"
-    end
-
-    it "returns nil when there is no entry for the passed key" do
-      -> { @headers.fetch("my-header") }.should raise_error(IndexError)
-    end
-  end
-
-  describe "when passed key, default" do
-    it "returns the header entry for the passed key" do
-      @headers["My-Header"] = "test"
-      @headers.fetch("My-Header", "bla").should == "test"
-
-      @headers.add_field("My-Other-Header", "a")
-      @headers.add_field("My-Other-Header", "b")
-      @headers.add_field("My-Other-Header", "c")
-      @headers.fetch("My-Other-Header", "bla").should == "a, b, c"
-    end
-
-    # TODO: This raises a NoMethodError: undefined method `join' for "bla":String
-    it "returns the default value when there is no entry for the passed key" do
-      @headers.fetch("My-Header", "bla").should == "bla"
-    end
-  end
-
-  describe "when passed key and block" do
-    it "returns the header entry for the passed key" do
-      @headers["My-Header"] = "test"
-      @headers.fetch("My-Header") {}.should == "test"
-
-      @headers.add_field("My-Other-Header", "a")
-      @headers.add_field("My-Other-Header", "b")
-      @headers.add_field("My-Other-Header", "c")
-      -> {
-        @result = @headers.fetch("My-Other-Header", "bla") {}
-      }.should complain(/block supersedes default value argument/)
-      @result.should == "a, b, c"
-    end
-
-    # TODO: This raises a NoMethodError: undefined method `join' for "redaeh-ym":String
-    it "yieldsand returns the block's return value when there is no entry for the passed key" do
-      @headers.fetch("My-Header") { |key| key.reverse }.should == "redaeh-ym"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/form_data_spec.rb b/spec/ruby/library/net/http/httpheader/form_data_spec.rb
deleted file mode 100644
index 9b29a03159..0000000000
--- a/spec/ruby/library/net/http/httpheader/form_data_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_form_data'
-
-describe "Net::HTTPHeader#form_data=" do
-  it_behaves_like :net_httpheader_set_form_data, :form_data=
-end
diff --git a/spec/ruby/library/net/http/httpheader/get_fields_spec.rb b/spec/ruby/library/net/http/httpheader/get_fields_spec.rb
deleted file mode 100644
index 1b623bf2a3..0000000000
--- a/spec/ruby/library/net/http/httpheader/get_fields_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#get_fields when passed key" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns an Array containing the values of the header entry with the passed key" do
-    @headers["My-Header"] = "a"
-    @headers.get_fields("My-Header").should == ["a"]
-
-    @headers.add_field("My-Header", "b")
-    @headers.get_fields("My-Header").should == ["a", "b"]
-  end
-
-  it "returns a copy of the header entry values" do
-    @headers["My-Header"] = "a"
-
-    @headers.get_fields("My-Header").clear
-    @headers.get_fields("My-Header").should == ["a"]
-
-    @headers.get_fields("My-Header") << "b"
-    @headers.get_fields("My-Header").should == ["a"]
-  end
-
-  it "returns nil for non-existing header entries" do
-    @headers.get_fields("My-Header").should be_nil
-    @headers.get_fields("My-Other-header").should be_nil
-  end
-
-  it "is case-insensitive" do
-    @headers["My-Header"] = "test"
-    @headers.get_fields("My-Header").should == ["test"]
-    @headers.get_fields("my-header").should == ["test"]
-    @headers.get_fields("MY-HEADER").should == ["test"]
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/initialize_http_header_spec.rb b/spec/ruby/library/net/http/httpheader/initialize_http_header_spec.rb
deleted file mode 100644
index efc5e7d0b2..0000000000
--- a/spec/ruby/library/net/http/httpheader/initialize_http_header_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#initialize_http_header when passed Hash" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.allocate
-  end
-
-  it "initializes the HTTP Header using the passed Hash" do
-    @headers.initialize_http_header("My-Header" => "test", "My-Other-Header" => "another test")
-    @headers["My-Header"].should == "test"
-    @headers["My-Other-Header"].should == "another test"
-  end
-
-  it "complains about duplicate keys when in verbose mode" do
-    -> do
-      @headers.initialize_http_header("My-Header" => "test", "my-header" => "another test")
-    end.should complain(/duplicated HTTP header/, verbose: true)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/key_spec.rb b/spec/ruby/library/net/http/httpheader/key_spec.rb
deleted file mode 100644
index 9099024229..0000000000
--- a/spec/ruby/library/net/http/httpheader/key_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#key? when passed key" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns true if the header entry with the passed key exists" do
-    @headers.key?("My-Header").should be_false
-    @headers["My-Header"] = "test"
-    @headers.key?("My-Header").should be_true
-  end
-
-  it "is case-insensitive" do
-    @headers["My-Header"] = "test"
-    @headers.key?("my-header").should be_true
-    @headers.key?("MY-HEADER").should be_true
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/length_spec.rb b/spec/ruby/library/net/http/httpheader/length_spec.rb
deleted file mode 100644
index 0d1da149f4..0000000000
--- a/spec/ruby/library/net/http/httpheader/length_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/size'
-
-describe "Net::HTTPHeader#length" do
-  it_behaves_like :net_httpheader_size, :length
-end
diff --git a/spec/ruby/library/net/http/httpheader/main_type_spec.rb b/spec/ruby/library/net/http/httpheader/main_type_spec.rb
deleted file mode 100644
index 3e18de6b5b..0000000000
--- a/spec/ruby/library/net/http/httpheader/main_type_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#main_type" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the 'main-content-type', as per 'Content-Type' header entry" do
-    @headers["Content-Type"] = "text/html"
-    @headers.main_type.should == "text"
-
-    @headers["Content-Type"] = "application/pdf"
-    @headers.main_type.should == "application"
-
-    @headers["Content-Type"] = "text/html;charset=utf-8"
-    @headers.main_type.should == "text"
-  end
-
-  it "returns nil if the 'Content-Type' header entry does not exist" do
-    @headers.main_type.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/proxy_basic_auth_spec.rb b/spec/ruby/library/net/http/httpheader/proxy_basic_auth_spec.rb
deleted file mode 100644
index 8b576ee164..0000000000
--- a/spec/ruby/library/net/http/httpheader/proxy_basic_auth_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#proxy_basic_auth when passed account, password" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "sets the 'Proxy-Authorization' Header entry for basic authorization" do
-    @headers.proxy_basic_auth("rubyspec", "rocks")
-    @headers["Proxy-Authorization"].should == "Basic cnVieXNwZWM6cm9ja3M="
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/range_length_spec.rb b/spec/ruby/library/net/http/httpheader/range_length_spec.rb
deleted file mode 100644
index b8fce4f690..0000000000
--- a/spec/ruby/library/net/http/httpheader/range_length_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#range_length" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the length of the Range represented by the 'Content-Range' header entry" do
-    @headers["Content-Range"] = "bytes 0-499/1234"
-    @headers.range_length.should eql(500)
-
-    @headers["Content-Range"] = "bytes 500-1233/1234"
-    @headers.range_length.should eql(734)
-  end
-
-  it "returns nil when there is no 'Content-Range' header entry" do
-    @headers.range_length.should be_nil
-  end
-
-  it "raises a Net::HTTPHeaderSyntaxError when the 'Content-Range' has an invalid format" do
-    @headers["Content-Range"] = "invalid"
-    -> { @headers.range_length }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Content-Range"] = "bytes 123-abc"
-    -> { @headers.range_length }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Content-Range"] = "bytes abc-123"
-    -> { @headers.range_length }.should raise_error(Net::HTTPHeaderSyntaxError)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/range_spec.rb b/spec/ruby/library/net/http/httpheader/range_spec.rb
deleted file mode 100644
index 005177f6be..0000000000
--- a/spec/ruby/library/net/http/httpheader/range_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_range'
-
-describe "Net::HTTPHeader#range" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns a Range object that represents the 'Range' header entry" do
-    @headers["Range"] = "bytes=0-499"
-    @headers.range.should == [0..499]
-
-    @headers["Range"] = "bytes=500-1233"
-    @headers.range.should == [500..1233]
-
-    @headers["Range"] = "bytes=10-"
-    @headers.range.should == [10..-1]
-
-    @headers["Range"] = "bytes=-10"
-    @headers.range.should == [-10..-1]
-  end
-
-  it "returns nil when there is no 'Range' header entry" do
-    @headers.range.should be_nil
-  end
-
-  it "raises a Net::HTTPHeaderSyntaxError when the 'Range' has an invalid format" do
-    @headers["Range"] = "invalid"
-    -> { @headers.range }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Range"] = "bytes 123-abc"
-    -> { @headers.range }.should raise_error(Net::HTTPHeaderSyntaxError)
-
-    @headers["Range"] = "bytes abc-123"
-    -> { @headers.range }.should raise_error(Net::HTTPHeaderSyntaxError)
-  end
-
-  it "raises a Net::HTTPHeaderSyntaxError when the 'Range' was not specified" do
-    @headers["Range"] = "bytes=-"
-    -> { @headers.range }.should raise_error(Net::HTTPHeaderSyntaxError)
-  end
-end
-
-describe "Net::HTTPHeader#range=" do
-  it_behaves_like :net_httpheader_set_range, :range=
-end
diff --git a/spec/ruby/library/net/http/httpheader/set_content_type_spec.rb b/spec/ruby/library/net/http/httpheader/set_content_type_spec.rb
deleted file mode 100644
index 125f7a7e0d..0000000000
--- a/spec/ruby/library/net/http/httpheader/set_content_type_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_content_type'
-
-describe "Net::HTTPHeader#set_content_type" do
-  it_behaves_like :net_httpheader_set_content_type, :set_content_type
-end
diff --git a/spec/ruby/library/net/http/httpheader/set_form_data_spec.rb b/spec/ruby/library/net/http/httpheader/set_form_data_spec.rb
deleted file mode 100644
index 14c66ae01c..0000000000
--- a/spec/ruby/library/net/http/httpheader/set_form_data_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_form_data'
-
-describe "Net::HTTPHeader#set_form_data" do
-  it_behaves_like :net_httpheader_set_form_data, :set_form_data
-end
diff --git a/spec/ruby/library/net/http/httpheader/set_range_spec.rb b/spec/ruby/library/net/http/httpheader/set_range_spec.rb
deleted file mode 100644
index 85b9c50422..0000000000
--- a/spec/ruby/library/net/http/httpheader/set_range_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/set_range'
-
-describe "Net::HTTPHeader#set_range" do
-  it_behaves_like :net_httpheader_set_range, :set_range
-end
diff --git a/spec/ruby/library/net/http/httpheader/shared/each_capitalized.rb b/spec/ruby/library/net/http/httpheader/shared/each_capitalized.rb
deleted file mode 100644
index 3bac409876..0000000000
--- a/spec/ruby/library/net/http/httpheader/shared/each_capitalized.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-describe :net_httpheader_each_capitalized, shared: true do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-    @headers["my-header"] = "test"
-    @headers.add_field("my-Other-Header", "a")
-    @headers.add_field("My-Other-header", "b")
-  end
-
-  describe "when passed a block" do
-    it "yields each header entry to the passed block (capitalized keys, values joined)" do
-      res = []
-      @headers.send(@method) do |key, value|
-        res << [key, value]
-      end
-      res.sort.should == [["My-Header", "test"], ["My-Other-Header", "a, b"]]
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Enumerator" do
-      enumerator = @headers.send(@method)
-      enumerator.should be_an_instance_of(Enumerator)
-
-      res = []
-      enumerator.each do |*key|
-        res << key
-      end
-      res.sort.should == [["My-Header", "test"], ["My-Other-Header", "a, b"]]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/shared/each_header.rb b/spec/ruby/library/net/http/httpheader/shared/each_header.rb
deleted file mode 100644
index 6bf3a6ddfe..0000000000
--- a/spec/ruby/library/net/http/httpheader/shared/each_header.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-describe :net_httpheader_each_header, shared: true do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-    @headers["My-Header"] = "test"
-    @headers.add_field("My-Other-Header", "a")
-    @headers.add_field("My-Other-Header", "b")
-  end
-
-  describe "when passed a block" do
-    it "yields each header entry to the passed block (keys in lower case, values joined)" do
-      res = []
-      @headers.send(@method) do |key, value|
-        res << [key, value]
-      end
-      res.sort.should == [["my-header", "test"], ["my-other-header", "a, b"]]
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Enumerator" do
-      enumerator = @headers.send(@method)
-      enumerator.should be_an_instance_of(Enumerator)
-
-      res = []
-      enumerator.each do |*key|
-        res << key
-      end
-      res.sort.should == [["my-header", "test"], ["my-other-header", "a, b"]]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/shared/each_name.rb b/spec/ruby/library/net/http/httpheader/shared/each_name.rb
deleted file mode 100644
index efc6a09dfd..0000000000
--- a/spec/ruby/library/net/http/httpheader/shared/each_name.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-describe :net_httpheader_each_name, shared: true do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-    @headers["My-Header"] = "test"
-    @headers.add_field("My-Other-Header", "a")
-    @headers.add_field("My-Other-Header", "b")
-  end
-
-  describe "when passed a block" do
-    it "yields each header key to the passed block (keys in lower case)" do
-      res = []
-      @headers.send(@method) do |key|
-        res << key
-      end
-      res.sort.should == ["my-header", "my-other-header"]
-    end
-  end
-
-  describe "when passed no block" do
-    it "returns an Enumerator" do
-      enumerator = @headers.send(@method)
-      enumerator.should be_an_instance_of(Enumerator)
-
-      res = []
-      enumerator.each do |key|
-        res << key
-      end
-      res.sort.should == ["my-header", "my-other-header"]
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/shared/set_range.rb b/spec/ruby/library/net/http/httpheader/shared/set_range.rb
deleted file mode 100644
index 87f51d46f3..0000000000
--- a/spec/ruby/library/net/http/httpheader/shared/set_range.rb
+++ /dev/null
@@ -1,89 +0,0 @@
-describe :net_httpheader_set_range, shared: true do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  describe "when passed nil" do
-    it "returns nil" do
-      @headers.send(@method, nil).should be_nil
-    end
-
-    it "deletes the 'Range' header entry" do
-      @headers["Range"] = "bytes 0-499/1234"
-      @headers.send(@method, nil)
-      @headers["Range"].should be_nil
-    end
-  end
-
-  describe "when passed Numeric" do
-    it "sets the 'Range' header entry based on the passed Numeric" do
-      @headers.send(@method, 10)
-      @headers["Range"].should == "bytes=0-9"
-
-      @headers.send(@method, -10)
-      @headers["Range"].should == "bytes=-10"
-
-      @headers.send(@method, 10.9)
-      @headers["Range"].should == "bytes=0-9"
-    end
-  end
-
-  describe "when passed Range" do
-    it "sets the 'Range' header entry based on the passed Range" do
-      @headers.send(@method, 10..200)
-      @headers["Range"].should == "bytes=10-200"
-
-      @headers.send(@method, 1..5)
-      @headers["Range"].should == "bytes=1-5"
-
-      @headers.send(@method, 1...5)
-      @headers["Range"].should == "bytes=1-4"
-
-      @headers.send(@method, 234..567)
-      @headers["Range"].should == "bytes=234-567"
-
-      @headers.send(@method, -5..-1)
-      @headers["Range"].should == "bytes=-5"
-
-      @headers.send(@method, 1..-1)
-      @headers["Range"].should == "bytes=1-"
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when the first Range element is negative" do
-      -> { @headers.send(@method, -10..5) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when the last Range element is negative" do
-      -> { @headers.send(@method, 10..-5) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when the last Range element is smaller than the first" do
-      -> { @headers.send(@method, 10..5) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-  end
-
-  describe "when passed start, end" do
-    it "sets the 'Range' header entry based on the passed start and length values" do
-      @headers.send(@method, 10, 200)
-      @headers["Range"].should == "bytes=10-209"
-
-      @headers.send(@method, 1, 5)
-      @headers["Range"].should == "bytes=1-5"
-
-      @headers.send(@method, 234, 567)
-      @headers["Range"].should == "bytes=234-800"
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when start is negative" do
-      -> { @headers.send(@method, -10, 5) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when start + length is negative" do
-      -> { @headers.send(@method, 10, -15) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-
-    it "raises a Net::HTTPHeaderSyntaxError when length is negative" do
-      -> { @headers.send(@method, 10, -4) }.should raise_error(Net::HTTPHeaderSyntaxError)
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/shared/size.rb b/spec/ruby/library/net/http/httpheader/shared/size.rb
deleted file mode 100644
index e2b1e4c22b..0000000000
--- a/spec/ruby/library/net/http/httpheader/shared/size.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-describe :net_httpheader_size, shared: true do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the number of header entries in self" do
-    @headers.send(@method).should eql(0)
-
-    @headers["a"] = "b"
-    @headers.send(@method).should eql(1)
-
-    @headers["b"] = "b"
-    @headers.send(@method).should eql(2)
-
-    @headers["c"] = "c"
-    @headers.send(@method).should eql(3)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/size_spec.rb b/spec/ruby/library/net/http/httpheader/size_spec.rb
deleted file mode 100644
index a7d78f96e0..0000000000
--- a/spec/ruby/library/net/http/httpheader/size_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-require_relative 'shared/size'
-
-describe "Net::HTTPHeader#size" do
-  it_behaves_like :net_httpheader_size, :size
-end
diff --git a/spec/ruby/library/net/http/httpheader/sub_type_spec.rb b/spec/ruby/library/net/http/httpheader/sub_type_spec.rb
deleted file mode 100644
index 3c73ca0027..0000000000
--- a/spec/ruby/library/net/http/httpheader/sub_type_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#sub_type" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns the 'sub-content-type', as per 'Content-Type' header entry" do
-    @headers["Content-Type"] = "text/html"
-    @headers.sub_type.should == "html"
-
-    @headers["Content-Type"] = "application/pdf"
-    @headers.sub_type.should == "pdf"
-
-    @headers["Content-Type"] = "text/html;charset=utf-8"
-    @headers.sub_type.should == "html"
-  end
-
-  it "returns nil if no 'sub-content-type' is set" do
-    @headers["Content-Type"] = "text"
-    @headers.sub_type.should be_nil
-
-    @headers["Content-Type"] = "text;charset=utf-8"
-    @headers.sub_type.should be_nil
-  end
-
-  it "returns nil if the 'Content-Type' header entry does not exist" do
-    @headers.sub_type.should be_nil
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/to_hash_spec.rb b/spec/ruby/library/net/http/httpheader/to_hash_spec.rb
deleted file mode 100644
index 8c1d36c30a..0000000000
--- a/spec/ruby/library/net/http/httpheader/to_hash_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#to_hash" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns a Hash representing all Header entries (keys in lower case, values as arrays)" do
-    @headers.to_hash.should == {}
-
-    @headers["My-Header"] = "test"
-    @headers.to_hash.should == { "my-header" => ["test"] }
-
-    @headers.add_field("My-Header", "another test")
-    @headers.to_hash.should == { "my-header" => ["test", "another test"] }
-  end
-
-  it "does not allow modifying the headers from the returned hash" do
-    @headers.to_hash["my-header"] = ["test"]
-    @headers.to_hash.should == {}
-    @headers.key?("my-header").should be_false
-  end
-end
diff --git a/spec/ruby/library/net/http/httpheader/type_params_spec.rb b/spec/ruby/library/net/http/httpheader/type_params_spec.rb
deleted file mode 100644
index e77be7ea85..0000000000
--- a/spec/ruby/library/net/http/httpheader/type_params_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'fixtures/classes'
-
-describe "Net::HTTPHeader#type_params" do
-  before :each do
-    @headers = NetHTTPHeaderSpecs::Example.new
-  end
-
-  it "returns additional 'Content-Type' information as a Hash" do
-    @headers["Content-Type"] = "text/html;charset=utf-8"
-    @headers.type_params.should == {"charset" => "utf-8"}
-
-    @headers["Content-Type"] = "text/html; charset=utf-8; rubyspec=rocks"
-    @headers.type_params.should == {"charset" => "utf-8", "rubyspec" => "rocks"}
-  end
-
-  it "returns an empty Hash when no additional 'Content-Type' information is set" do
-    @headers.type_params.should == {}
-
-    @headers["Content-Type"] = "text/html"
-    @headers.type_params.should == {}
-  end
-end
diff --git a/spec/ruby/library/net/http/httprequest/initialize_spec.rb b/spec/ruby/library/net/http/httprequest/initialize_spec.rb
deleted file mode 100644
index 88e9fb1c77..0000000000
--- a/spec/ruby/library/net/http/httprequest/initialize_spec.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-module NetHTTPRequestSpecs
-  class TestRequest < Net::HTTPRequest
-    METHOD = "TEST"
-    REQUEST_HAS_BODY  = false
-    RESPONSE_HAS_BODY = true
-  end
-end
-
-describe "Net::HTTPRequest#initialize" do
-  before :each do
-    @req = NetHTTPRequestSpecs::TestRequest.allocate
-  end
-
-  it "uses the METHOD constants to set the request method" do
-    @req.send(:initialize, "/some/path")
-    @req.method.should == "TEST"
-  end
-
-  it "uses the REQUEST_HAS_BODY to set whether the Request has a body or not" do
-    @req.send(:initialize, "/some/path")
-    @req.request_body_permitted?.should be_false
-  end
-
-  it "uses the RESPONSE_HAS_BODY to set whether the Response can have a body or not" do
-    @req.send(:initialize, "/some/path")
-    @req.response_body_permitted?.should be_true
-  end
-
-  describe "when passed path" do
-    it "sets self's path to the passed path" do
-      @req.send(:initialize, "/some/path")
-      @req.path.should == "/some/path"
-    end
-  end
-
-  describe "when passed path, headers" do
-    it "uses the passed headers Hash to initialize self's header entries" do
-      @req.send(:initialize, "/some/path", "Content-Type" => "text/html")
-      @req["Content-Type"].should == "text/html"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/body_permitted_spec.rb b/spec/ruby/library/net/http/httpresponse/body_permitted_spec.rb
deleted file mode 100644
index 68a0454f79..0000000000
--- a/spec/ruby/library/net/http/httpresponse/body_permitted_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse.body_permitted?" do
-  it "returns true if this response type can have a response body" do
-    Net::HTTPUnknownResponse.body_permitted?.should == true
-    Net::HTTPInformation.body_permitted?.should == false
-    Net::HTTPSuccess.body_permitted?.should == true
-    Net::HTTPRedirection.body_permitted?.should == true
-    Net::HTTPClientError.body_permitted?.should == true
-    Net::HTTPServerError.body_permitted?.should == true
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/body_spec.rb b/spec/ruby/library/net/http/httpresponse/body_spec.rb
deleted file mode 100644
index 79569441f1..0000000000
--- a/spec/ruby/library/net/http/httpresponse/body_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/body'
-
-describe "Net::HTTPResponse#body" do
-  it_behaves_like :net_httpresponse_body, :body
-end
diff --git a/spec/ruby/library/net/http/httpresponse/code_spec.rb b/spec/ruby/library/net/http/httpresponse/code_spec.rb
deleted file mode 100644
index 114277cb43..0000000000
--- a/spec/ruby/library/net/http/httpresponse/code_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#code" do
-  it "returns the result code string" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.code.should == "???"
-
-    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
-    res.code.should == "1xx"
-
-    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
-    res.code.should == "2xx"
-
-    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
-    res.code.should == "3xx"
-
-    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    res.code.should == "4xx"
-
-    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
-    res.code.should == "5xx"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/code_type_spec.rb b/spec/ruby/library/net/http/httpresponse/code_type_spec.rb
deleted file mode 100644
index fa2d572e9a..0000000000
--- a/spec/ruby/library/net/http/httpresponse/code_type_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#code_type" do
-  it "returns self's class" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.code_type.should == Net::HTTPUnknownResponse
-
-    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
-    res.code_type.should == Net::HTTPInformation
-
-    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
-    res.code_type.should == Net::HTTPSuccess
-
-    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
-    res.code_type.should == Net::HTTPRedirection
-
-    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    res.code_type.should == Net::HTTPClientError
-
-    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
-    res.code_type.should == Net::HTTPServerError
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/entity_spec.rb b/spec/ruby/library/net/http/httpresponse/entity_spec.rb
deleted file mode 100644
index f1639042c1..0000000000
--- a/spec/ruby/library/net/http/httpresponse/entity_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require_relative 'shared/body'
-
-describe "Net::HTTPResponse#entity" do
-  it_behaves_like :net_httpresponse_body, :entity
-end
diff --git a/spec/ruby/library/net/http/httpresponse/error_spec.rb b/spec/ruby/library/net/http/httpresponse/error_spec.rb
deleted file mode 100644
index d2b2f53d89..0000000000
--- a/spec/ruby/library/net/http/httpresponse/error_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#error!" do
-  it "raises self's class 'EXCEPTION_TYPE' Exception" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    -> { res.error! }.should raise_error(Net::HTTPError)
-
-    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
-    -> { res.error! }.should raise_error(Net::HTTPError)
-
-    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
-    -> { res.error! }.should raise_error(Net::HTTPError)
-
-    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
-    -> { res.error! }.should raise_error(Net::HTTPRetriableError)
-
-    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      -> { res.error! }.should raise_error(Net::HTTPServerException)
-    end
-    ruby_version_is "2.6" do
-      -> { res.error! }.should raise_error(Net::HTTPClientException)
-    end
-
-    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
-    -> { res.error! }.should raise_error(Net::HTTPFatalError)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/error_type_spec.rb b/spec/ruby/library/net/http/httpresponse/error_type_spec.rb
deleted file mode 100644
index 6705f8b1aa..0000000000
--- a/spec/ruby/library/net/http/httpresponse/error_type_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#error_type" do
-  it "returns self's class 'EXCEPTION_TYPE' constant" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.error_type.should == Net::HTTPError
-
-    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
-    res.error_type.should == Net::HTTPError
-
-    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
-    res.error_type.should == Net::HTTPError
-
-    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
-    res.error_type.should == Net::HTTPRetriableError
-
-    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      res.error_type.should == Net::HTTPServerException
-    end
-    ruby_version_is "2.6" do
-      res.error_type.should == Net::HTTPClientException
-    end
-
-    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
-    res.error_type.should == Net::HTTPFatalError
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb b/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb
deleted file mode 100644
index c0812cd322..0000000000
--- a/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse.exception_type" do
-  it "returns self's 'EXCEPTION_TYPE' constant" do
-    Net::HTTPUnknownResponse.exception_type.should == Net::HTTPError
-    Net::HTTPInformation.exception_type.should == Net::HTTPError
-    Net::HTTPSuccess.exception_type.should == Net::HTTPError
-    Net::HTTPRedirection.exception_type.should == Net::HTTPRetriableError
-    ruby_version_is ""..."2.6" do
-      Net::HTTPClientError.exception_type.should == Net::HTTPServerException
-    end
-    ruby_version_is "2.6" do
-      Net::HTTPClientError.exception_type.should == Net::HTTPClientException
-    end
-    Net::HTTPServerError.exception_type.should == Net::HTTPFatalError
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/header_spec.rb b/spec/ruby/library/net/http/httpresponse/header_spec.rb
deleted file mode 100644
index a9615feda8..0000000000
--- a/spec/ruby/library/net/http/httpresponse/header_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#header" do
-  it "returns self" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.response.should equal(res)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/http_version_spec.rb b/spec/ruby/library/net/http/httpresponse/http_version_spec.rb
deleted file mode 100644
index db85696d77..0000000000
--- a/spec/ruby/library/net/http/httpresponse/http_version_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#http_version" do
-  it "returns self's http version" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.http_version.should == "1.0"
-
-    res = Net::HTTPUnknownResponse.new("1.1", "???", "test response")
-    res.http_version.should == "1.1"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/initialize_spec.rb b/spec/ruby/library/net/http/httpresponse/initialize_spec.rb
deleted file mode 100644
index eb77e2e277..0000000000
--- a/spec/ruby/library/net/http/httpresponse/initialize_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#initialize when passed http_version, response_code, response_message" do
-  it "sets self http_version, response_code and response_message to the passed values" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.http_version.should == "1.0"
-    res.code.should == "???"
-    res.message.should == "test response"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/inspect_spec.rb b/spec/ruby/library/net/http/httpresponse/inspect_spec.rb
deleted file mode 100644
index 1e1a2c7cc7..0000000000
--- a/spec/ruby/library/net/http/httpresponse/inspect_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-
-describe "Net::HTTPResponse#inspect" do
-  it "returns a String representation of self" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=false>"
-
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    socket = Net::BufferedIO.new(StringIO.new("test body"))
-    res.reading_body(socket, true) {}
-    res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=true>"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/message_spec.rb b/spec/ruby/library/net/http/httpresponse/message_spec.rb
deleted file mode 100644
index ae8e3678a1..0000000000
--- a/spec/ruby/library/net/http/httpresponse/message_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#message" do
-  it "returns self's response message" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.message.should == "test response"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/msg_spec.rb b/spec/ruby/library/net/http/httpresponse/msg_spec.rb
deleted file mode 100644
index 0e5e7eb4aa..0000000000
--- a/spec/ruby/library/net/http/httpresponse/msg_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#msg" do
-  it "returns self's response message" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.message.should == "test response"
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/read_body_spec.rb b/spec/ruby/library/net/http/httpresponse/read_body_spec.rb
deleted file mode 100644
index 99d8e5fa88..0000000000
--- a/spec/ruby/library/net/http/httpresponse/read_body_spec.rb
+++ /dev/null
@@ -1,85 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#read_body" do
-  before :each do
-    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    @socket = Net::BufferedIO.new(StringIO.new("test body"))
-  end
-
-  describe "when passed no arguments" do
-    it "returns the read body" do
-      @res.reading_body(@socket, true) do
-        @res.read_body.should == "test body"
-      end
-    end
-
-    it "returns the previously read body if called a second time" do
-      @res.reading_body(@socket, true) do
-        @res.read_body.should equal(@res.read_body)
-      end
-    end
-  end
-
-  describe "when passed a buffer" do
-    it "reads the body to the passed buffer" do
-      @res.reading_body(@socket, true) do
-        buffer = ""
-        @res.read_body(buffer)
-        buffer.should == "test body"
-      end
-    end
-
-    it "returns the passed buffer" do
-      @res.reading_body(@socket, true) do
-        buffer = ""
-        @res.read_body(buffer).should equal(buffer)
-      end
-    end
-
-    it "raises an IOError if called a second time" do
-      @res.reading_body(@socket, true) do
-        @res.read_body("")
-        -> { @res.read_body("") }.should raise_error(IOError)
-      end
-    end
-  end
-
-  describe "when passed a block" do
-    it "reads the body and yields it to the passed block (in chunks)" do
-      @res.reading_body(@socket, true) do
-        yielded = false
-
-        buffer = ""
-        @res.read_body do |body|
-          yielded = true
-          buffer << body
-        end
-
-        yielded.should be_true
-        buffer.should == "test body"
-      end
-    end
-
-    it "returns the ReadAdapter" do
-      @res.reading_body(@socket, true) do
-        @res.read_body { nil }.should be_kind_of(Net::ReadAdapter)
-      end
-    end
-
-    it "raises an IOError if called a second time" do
-      @res.reading_body(@socket, true) do
-        @res.read_body {}
-        -> { @res.read_body {} }.should raise_error(IOError)
-      end
-    end
-  end
-
-  describe "when passed buffer and block" do
-    it "raises an ArgumentError" do
-      @res.reading_body(@socket, true) do
-        -> { @res.read_body("") {} }.should raise_error(ArgumentError)
-      end
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/read_header_spec.rb b/spec/ruby/library/net/http/httpresponse/read_header_spec.rb
deleted file mode 100644
index 6af8c6bd6a..0000000000
--- a/spec/ruby/library/net/http/httpresponse/read_header_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#read_header" do
-  it "returns self" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.response.should equal(res)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/read_new_spec.rb b/spec/ruby/library/net/http/httpresponse/read_new_spec.rb
deleted file mode 100644
index 73c7ddc100..0000000000
--- a/spec/ruby/library/net/http/httpresponse/read_new_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse.read_new" do
-  it "creates a HTTPResponse object based on the response read from the passed socket" do
-    socket = Net::BufferedIO.new(StringIO.new(<<EOS))
-HTTP/1.1 200 OK
-Content-Type: text/html; charset=utf-8
-
-test-body
-EOS
-    response = Net::HTTPResponse.read_new(socket)
-
-    response.should be_kind_of(Net::HTTPOK)
-    response.code.should == "200"
-    response["Content-Type"].should == "text/html; charset=utf-8"
-
-    response.reading_body(socket, true) do
-      response.body.should == "test-body\n"
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/reading_body_spec.rb b/spec/ruby/library/net/http/httpresponse/reading_body_spec.rb
deleted file mode 100644
index ebdab891e1..0000000000
--- a/spec/ruby/library/net/http/httpresponse/reading_body_spec.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-require "stringio"
-
-describe "Net::HTTPResponse#reading_body" do
-  before :each do
-    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    @socket = Net::BufferedIO.new(StringIO.new("test body"))
-  end
-
-  describe "when body_allowed is true" do
-    it "reads and returns the response body for self from the passed socket" do
-      @res.reading_body(@socket, true) {}.should == "test body"
-      @res.body.should == "test body"
-    end
-
-    it "yields the passed block before reading the body" do
-      yielded = false
-
-      @res.reading_body(@socket, true) do
-        @res.inspect.should == "#<Net::HTTPUnknownResponse ??? test response readbody=false>"
-        yielded = true
-      end
-
-      yielded.should be_true
-    end
-
-    describe "but the response type is not allowed to have a body" do
-      before :each do
-        @res = Net::HTTPInformation.new("1.0", "???", "test response")
-      end
-
-      it "returns nil" do
-        @res.reading_body(@socket, false) {}.should be_nil
-        @res.body.should be_nil
-      end
-
-      it "yields the passed block" do
-        yielded = false
-        @res.reading_body(@socket, true) { yielded = true }
-        yielded.should be_true
-      end
-    end
-  end
-
-  describe "when body_allowed is false" do
-    it "returns nil" do
-      @res.reading_body(@socket, false) {}.should be_nil
-      @res.body.should be_nil
-    end
-
-    it "yields the passed block" do
-      yielded = false
-      @res.reading_body(@socket, true) { yielded = true }
-      yielded.should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/response_spec.rb b/spec/ruby/library/net/http/httpresponse/response_spec.rb
deleted file mode 100644
index f6035f3695..0000000000
--- a/spec/ruby/library/net/http/httpresponse/response_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#response" do
-  it "returns self" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    res.response.should equal(res)
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/shared/body.rb b/spec/ruby/library/net/http/httpresponse/shared/body.rb
deleted file mode 100644
index 91d5fe6375..0000000000
--- a/spec/ruby/library/net/http/httpresponse/shared/body.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-describe :net_httpresponse_body, shared: true do
-  before :each do
-    @res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    @socket = Net::BufferedIO.new(StringIO.new("test body"))
-  end
-
-  it "returns the read body" do
-    @res.reading_body(@socket, true) do
-      @res.send(@method).should == "test body"
-    end
-  end
-
-  it "returns the previously read body if called a second time" do
-    @res.reading_body(@socket, true) do
-      @res.send(@method).should equal(@res.send(@method))
-    end
-  end
-end
diff --git a/spec/ruby/library/net/http/httpresponse/value_spec.rb b/spec/ruby/library/net/http/httpresponse/value_spec.rb
deleted file mode 100644
index 4a5930d4e5..0000000000
--- a/spec/ruby/library/net/http/httpresponse/value_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'net/http'
-
-describe "Net::HTTPResponse#value" do
-  it "raises an HTTP error for non 2xx HTTP Responses" do
-    res = Net::HTTPUnknownResponse.new("1.0", "???", "test response")
-    -> { res.value }.should raise_error(Net::HTTPError)
-
-    res = Net::HTTPInformation.new("1.0", "1xx", "test response")
-    -> { res.value }.should raise_error(Net::HTTPError)
-
-    res = Net::HTTPSuccess.new("1.0", "2xx", "test response")
-    -> { res.value }.should_not raise_error(Net::HTTPError)
-
-    res = Net::HTTPRedirection.new("1.0", "3xx", "test response")
-    -> { res.value }.should raise_error(Net::HTTPRetriableError)
-
-    res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      -> { res.value }.should raise_error(Net::HTTPServerException)
-    end
-    ruby_version_is "2.6" do
-      -> { res.value }.should raise_error(Net::HTTPClientException)
-    end
-
-    res = Net::HTTPServerError.new("1.0", "5xx", "test response")
-    -> { res.value }.should raise_error(Net::HTTPFatalError)
-  end
-end
diff --git a/spec/ruby/library/objectspace/dump_all_spec.rb b/spec/ruby/library/objectspace/dump_all_spec.rb
new file mode 100644
index 0000000000..c92812ebd5
--- /dev/null
+++ b/spec/ruby/library/objectspace/dump_all_spec.rb
@@ -0,0 +1,112 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.dump_all" do
+  it "dumps Ruby heap to string when passed output: :string" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace")
+      string = "abc"
+      dump = ObjectSpace.dump_all(output: :string)
+      puts dump.class
+      puts dump.include?('"value":"abc"')
+    RUBY
+
+    stdout.should == "String\ntrue\n"
+  end
+
+  it "dumps Ruby heap to a temporary file when passed output: :file" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace")
+      string = "abc"
+      file = ObjectSpace.dump_all(output: :file)
+
+      begin
+        file.flush
+        file.rewind
+        content = file.read
+
+        puts file.class
+        puts content.include?('"value":"abc"')
+      ensure
+        file.close
+        File.unlink file.path
+      end
+    RUBY
+
+    stdout.should == "File\ntrue\n"
+  end
+
+  it "dumps Ruby heap to a temporary file when :output not specified" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace")
+      string = "abc"
+      file = ObjectSpace.dump_all
+
+      begin
+        file.flush
+        file.rewind
+        content = file.read
+
+        puts file.class
+        puts content.include?('"value":"abc"')
+      ensure
+        file.close
+        File.unlink file.path
+      end
+    RUBY
+
+    stdout.should == "File\ntrue\n"
+  end
+
+  it "dumps Ruby heap to a temporary file when passed output: :nil" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace")
+    string = "abc"
+    file = ObjectSpace.dump_all(output: nil)
+
+    begin
+      file.flush
+      file.rewind
+      content = file.read
+
+      puts file.class
+      puts content.include?('"value":"abc"')
+    ensure
+      file.close
+      File.unlink file.path
+    end
+    RUBY
+
+    stdout.should == "File\ntrue\n"
+  end
+
+  it "dumps Ruby heap to stdout when passed output: :stdout" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace")
+      string = "abc"
+      ObjectSpace.dump_all(output: :stdout)
+    RUBY
+
+    stdout.should.include?('"value":"abc"')
+  end
+
+  it "dumps Ruby heap to provided IO when passed output: IO" do
+    stdout = ruby_exe(<<~RUBY, options: "-robjspace -rtempfile")
+      string = "abc"
+      io = Tempfile.create("object_space_dump_all")
+
+      begin
+        result = ObjectSpace.dump_all(output: io)
+        io.rewind
+        content = io.read
+
+        puts result.equal?(io)
+        puts content.include?('"value":"abc"')
+      ensure
+        io.close
+        File.unlink io.path
+      end
+    RUBY
+
+    stdout.should == "true\ntrue\n"
+  end
+
+  it "raises ArgumentError when passed not supported :output value" do
+    -> { ObjectSpace.dump_all(output: Object.new) }.should.raise(ArgumentError, /wrong output option/)
+  end
+end
diff --git a/spec/ruby/library/objectspace/dump_spec.rb b/spec/ruby/library/objectspace/dump_spec.rb
new file mode 100644
index 0000000000..4b5e0da198
--- /dev/null
+++ b/spec/ruby/library/objectspace/dump_spec.rb
@@ -0,0 +1,70 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.dump" do
+  it "dumps the content of object as JSON" do
+    require 'json'
+    string = ObjectSpace.dump("abc")
+    dump = JSON.parse(string)
+
+    dump['type'].should == "STRING"
+    dump['value'].should == "abc"
+  end
+
+  it "dumps to string when passed output: :string" do
+    string = ObjectSpace.dump("abc", output: :string)
+    string.should.is_a?(String)
+    string.should.include?('"value":"abc"')
+  end
+
+  it "dumps to string when :output not specified" do
+    string = ObjectSpace.dump("abc")
+    string.should.is_a?(String)
+    string.should.include?('"value":"abc"')
+  end
+
+  it "dumps to a temporary file when passed output: :file" do
+    file = ObjectSpace.dump("abc", output: :file)
+    file.should.is_a?(File)
+
+    file.rewind
+    content = file.read
+    content.should.include?('"value":"abc"')
+  ensure
+    file.close
+    File.unlink file.path
+  end
+
+  it "dumps to a temporary file when passed output: :nil" do
+    file = ObjectSpace.dump("abc", output: nil)
+    file.should.is_a?(File)
+
+    file.rewind
+    file.read.should.include?('"value":"abc"')
+  ensure
+    file.close
+    File.unlink file.path
+  end
+
+  it "dumps to stdout when passed output: :stdout" do
+    stdout = ruby_exe('ObjectSpace.dump("abc", output: :stdout)', options: "-robjspace").chomp
+    stdout.should.include?('"value":"abc"')
+  end
+
+  it "dumps to provided IO when passed output: IO" do
+    filename = tmp("io_read.txt")
+    io = File.open(filename, "w+")
+    result = ObjectSpace.dump("abc", output: io)
+    result.should.equal? io
+
+    io.rewind
+    io.read.should.include?('"value":"abc"')
+  ensure
+    io.close
+    rm_r filename
+  end
+
+  it "raises ArgumentError when passed not supported :output value" do
+    -> { ObjectSpace.dump("abc", output: Object.new) }.should.raise(ArgumentError, /wrong output option/)
+  end
+end
diff --git a/spec/ruby/library/objectspace/fixtures/trace.rb b/spec/ruby/library/objectspace/fixtures/trace.rb
new file mode 100644
index 0000000000..e53a7a0cac
--- /dev/null
+++ b/spec/ruby/library/objectspace/fixtures/trace.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: false
+require "objspace/trace"
+a = "foo"
+b = "b" + "a" + "r"
+c = 42
+p a, b, c
diff --git a/spec/ruby/library/objectspace/memsize_of_all_spec.rb b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
new file mode 100644
index 0000000000..9fc6e8be9d
--- /dev/null
+++ b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.memsize_of_all" do
+  it "returns a non-zero Integer for all objects" do
+    ObjectSpace.memsize_of_all.should.is_a?(Integer)
+    ObjectSpace.memsize_of_all.should > 0
+  end
+
+  it "returns a non-zero Integer for Class" do
+    ObjectSpace.memsize_of_all(Class).should.is_a?(Integer)
+    ObjectSpace.memsize_of_all(Class).should > 0
+  end
+
+  it "increases when a new object is allocated" do
+    c = Class.new
+    before = ObjectSpace.memsize_of_all(c)
+    o = c.new
+    after = ObjectSpace.memsize_of_all(c)
+    after.should > before
+  end
+end
diff --git a/spec/ruby/library/objectspace/memsize_of_spec.rb b/spec/ruby/library/objectspace/memsize_of_spec.rb
index 06a80d9f9c..9c8aea4e84 100644
--- a/spec/ruby/library/objectspace/memsize_of_spec.rb
+++ b/spec/ruby/library/objectspace/memsize_of_spec.rb
@@ -12,9 +12,13 @@ describe "ObjectSpace.memsize_of" do
     ObjectSpace.memsize_of(42).should == 0
   end
 
-  it "returns an Integer for an Object" do
+  it "returns 0 for literal Symbols" do
+    ObjectSpace.memsize_of(:object_space_memsize_spec_static_sym).should == 0
+  end
+
+  it "returns a positive Integer for an Object" do
     obj = Object.new
-    ObjectSpace.memsize_of(obj).should be_kind_of(Integer)
+    ObjectSpace.memsize_of(obj).should.is_a?(Integer)
     ObjectSpace.memsize_of(obj).should > 0
   end
 
diff --git a/spec/ruby/library/objectspace/reachable_objects_from_spec.rb b/spec/ruby/library/objectspace/reachable_objects_from_spec.rb
index 7e70bc8569..4620bdec31 100644
--- a/spec/ruby/library/objectspace/reachable_objects_from_spec.rb
+++ b/spec/ruby/library/objectspace/reachable_objects_from_spec.rb
@@ -16,7 +16,7 @@ describe "ObjectSpace.reachable_objects_from" do
   end
 
   it "enumerates objects directly reachable from a given object" do
-    ObjectSpace.reachable_objects_from(['a', 'b', 'c']).should include(Array, 'a', 'b', 'c')
+    ObjectSpace.reachable_objects_from(['a', 'b', 'c']).to_set.should >= Set[Array, 'a', 'b', 'c']
     ObjectSpace.reachable_objects_from(Object.new).should == [Object]
   end
 
@@ -24,7 +24,7 @@ describe "ObjectSpace.reachable_objects_from" do
     obj = Object.new
     ary = [obj]
     reachable = ObjectSpace.reachable_objects_from(ary)
-    reachable.should include(obj)
+    reachable.should.include?(obj)
   end
 
   it "finds an object stored in a copy-on-write Array" do
@@ -33,29 +33,27 @@ describe "ObjectSpace.reachable_objects_from" do
     ary = [removed, obj]
     ary.shift
     reachable = ObjectSpace.reachable_objects_from(ary)
-    reachable.should include(obj)
-    reachable.should_not include(removed)
+    reachable.should.include?(obj)
+    reachable.should_not.include?(removed)
   end
 
   it "finds an object stored in a Queue" do
-    require 'thread'
     o = Object.new
     q = Queue.new
     q << o
 
     reachable = ObjectSpace.reachable_objects_from(q)
     reachable = reachable + reachable.flat_map { |r| ObjectSpace.reachable_objects_from(r) }
-    reachable.should include(o)
+    reachable.should.include?(o)
   end
 
   it "finds an object stored in a SizedQueue" do
-    require 'thread'
     o = Object.new
     q = SizedQueue.new(3)
     q << o
 
     reachable = ObjectSpace.reachable_objects_from(q)
     reachable = reachable + reachable.flat_map { |r| ObjectSpace.reachable_objects_from(r) }
-    reachable.should include(o)
+    reachable.should.include?(o)
   end
 end
diff --git a/spec/ruby/library/objectspace/trace_object_allocations_spec.rb b/spec/ruby/library/objectspace/trace_object_allocations_spec.rb
new file mode 100644
index 0000000000..0bb6efbfa5
--- /dev/null
+++ b/spec/ruby/library/objectspace/trace_object_allocations_spec.rb
@@ -0,0 +1,163 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.trace_object_allocations" do
+  def has_class_frame?
+    Class.new {
+      attr_reader :c
+
+      def initialize
+        @c = caller_locations.first.label =~ /new/
+      end
+    }.new.c
+  end
+
+  def obj_class_path
+    has_class_frame? ? "Class" : nil
+  end
+
+  it "runs a block" do
+    ScratchPad.clear
+    ObjectSpace.trace_object_allocations do
+      ScratchPad.record :a
+    end
+    ScratchPad.recorded.should == :a
+  end
+
+  it "records info for allocation_class_path" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == obj_class_path
+      a = [1, 2, 3]
+      ObjectSpace.allocation_class_path(a).should == nil
+    end
+  end
+
+  it "records info for allocation_generation" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_generation(o).should.kind_of?(Integer)
+      a = [1, 2, 3]
+      ObjectSpace.allocation_generation(a).should.kind_of?(Integer)
+    end
+  end
+
+  it "records info for allocation_method_id" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_method_id(o).should == (has_class_frame? ? :new : nil)
+      a = [1, 2, 3]
+      ObjectSpace.allocation_method_id(a).should == nil
+    end
+  end
+
+  it "records info for allocation_sourcefile" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_sourcefile(o).should == __FILE__
+      a = [1, 2, 3]
+      ObjectSpace.allocation_sourcefile(a).should == __FILE__
+    end
+  end
+
+  it "records info for allocation_sourceline" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_sourceline(o).should == __LINE__ - 1
+      a = [1, 2, 3]
+      ObjectSpace.allocation_sourceline(a).should == __LINE__ - 1
+    end
+  end
+
+  it "can be cleared using trace_object_allocations_clear" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == obj_class_path
+      ObjectSpace.trace_object_allocations_clear
+      ObjectSpace.allocation_class_path(o).should == nil
+    end
+  end
+
+  it "does not clears allocation data after returning" do
+    o = nil
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+    end
+    ObjectSpace.allocation_class_path(o).should == obj_class_path
+  end
+
+  it "can be used without a block using trace_object_allocations_start and _stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == obj_class_path
+      a = [1, 2, 3]
+      ObjectSpace.allocation_class_path(a).should == nil
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+
+  it "does not clears allocation data after trace_object_allocations_stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+    ObjectSpace.allocation_class_path(o).should == obj_class_path
+  end
+
+  it "can be nested" do
+    ObjectSpace.trace_object_allocations do
+      ObjectSpace.trace_object_allocations do
+        o = Object.new
+        ObjectSpace.allocation_class_path(o).should == obj_class_path
+      end
+    end
+  end
+
+  it "can be nested without a block using trace_object_allocations_start and _stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      ObjectSpace.trace_object_allocations_start
+      begin
+        o = Object.new
+        ObjectSpace.allocation_class_path(o).should == obj_class_path
+      ensure
+        ObjectSpace.trace_object_allocations_stop
+      end
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+
+  it "can be nested with more _stop than _start" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == obj_class_path
+      ObjectSpace.trace_object_allocations_stop
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+
+  it "returns nil for class_path, generation, method_id, sourcefile, and sourceline for immutable objects" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      one = nil
+      two = 42
+      three = :foo
+      [one, two, three].each do |i|
+        ObjectSpace.allocation_class_path(i).should == nil
+        ObjectSpace.allocation_generation(i).should == nil
+        ObjectSpace.allocation_method_id(i).should == nil
+        ObjectSpace.allocation_sourcefile(i).should == nil
+        ObjectSpace.allocation_sourceline(i).should == nil
+      end
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+end
diff --git a/spec/ruby/library/objectspace/trace_spec.rb b/spec/ruby/library/objectspace/trace_spec.rb
new file mode 100644
index 0000000000..3957dc930d
--- /dev/null
+++ b/spec/ruby/library/objectspace/trace_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe 'require "objspace/trace"' do
+  it "shows object allocation sites" do
+    file = fixture(__FILE__ , "trace.rb")
+    ruby_exe(file, args: "2>&1").lines(chomp: true).should == [
+      "objspace/trace is enabled",
+      "\"foo\" @ #{file}:3",
+      "\"bar\" @ #{file}:4",
+      "42"
+    ]
+  end
+end
diff --git a/spec/ruby/library/observer/notify_observers_spec.rb b/spec/ruby/library/observer/notify_observers_spec.rb
index 31f82e9266..6f3f984637 100644
--- a/spec/ruby/library/observer/notify_observers_spec.rb
+++ b/spec/ruby/library/observer/notify_observers_spec.rb
@@ -18,7 +18,7 @@ describe "Observer#notify_observers" do
   it "verifies observer responds to update" do
     -> {
       @observable.add_observer(@observable)
-    }.should raise_error(NoMethodError)
+    }.should.raise(NoMethodError)
   end
 
   it "receives the callback" do
diff --git a/spec/ruby/library/open3/popen3_spec.rb b/spec/ruby/library/open3/popen3_spec.rb
index d3103ad3cb..3651bd516c 100644
--- a/spec/ruby/library/open3/popen3_spec.rb
+++ b/spec/ruby/library/open3/popen3_spec.rb
@@ -5,10 +5,10 @@ describe "Open3.popen3" do
   it "returns in, out, err and a thread waiting the process" do
     stdin, out, err, waiter = Open3.popen3(ruby_cmd("print :foo"))
     begin
-      stdin.should be_kind_of IO
-      out.should be_kind_of IO
-      err.should be_kind_of IO
-      waiter.should be_kind_of Thread
+      stdin.should.is_a? IO
+      out.should.is_a? IO
+      err.should.is_a? IO
+      waiter.should.is_a? Thread
 
       out.read.should == "foo"
     ensure
diff --git a/spec/ruby/library/openssl/cipher_spec.rb b/spec/ruby/library/openssl/cipher_spec.rb
index f66f25f9c6..91da1c592c 100644
--- a/spec/ruby/library/openssl/cipher_spec.rb
+++ b/spec/ruby/library/openssl/cipher_spec.rb
@@ -4,6 +4,6 @@ require 'openssl'
 
 describe "OpenSSL::Cipher's CipherError" do
   it "exists under OpenSSL::Cipher namespace" do
-    OpenSSL::Cipher.should have_constant :CipherError
+    OpenSSL::Cipher.should.const_defined?(:CipherError, false)
   end
 end
diff --git a/spec/ruby/library/openssl/config/freeze_spec.rb b/spec/ruby/library/openssl/config/freeze_spec.rb
deleted file mode 100644
index 1876095d9f..0000000000
--- a/spec/ruby/library/openssl/config/freeze_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative '../shared/constants'
-
-require 'openssl'
-
-describe "OpenSSL::Config#freeze" do
-  it "needs to be reviewed for completeness"
-
-  it "freezes" do
-    c = OpenSSL::Config.new
-    -> {
-      c['foo'] = [ ['key', 'value'] ]
-    }.should_not raise_error
-    c.freeze
-    c.frozen?.should be_true
-    -> {
-      c['foo'] = [ ['key', 'value'] ]
-    }.should raise_error(TypeError)
-  end
-end
diff --git a/spec/ruby/library/openssl/digest/append_spec.rb b/spec/ruby/library/openssl/digest/append_spec.rb
new file mode 100644
index 0000000000..08802b7253
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/append_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/update'
+
+describe "OpenSSL::Digest#<<" do
+  it_behaves_like :openssl_digest_update, :<<
+end
diff --git a/spec/ruby/library/openssl/digest/block_length_spec.rb b/spec/ruby/library/openssl/digest/block_length_spec.rb
new file mode 100644
index 0000000000..444ed9d20d
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/block_length_spec.rb
@@ -0,0 +1,44 @@
+require_relative '../../../spec_helper'
+require_relative '../../../library/digest/sha1/shared/constants'
+require_relative '../../../library/digest/sha256/shared/constants'
+require_relative '../../../library/digest/sha384/shared/constants'
+require_relative '../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe "OpenSSL::Digest#block_length" do
+  context "when the digest object is created via a name argument" do
+    it "returns a SHA1 block length" do
+      OpenSSL::Digest.new('sha1').block_length.should == SHA1Constants::BlockLength
+    end
+
+    it "returns a SHA256 block length" do
+      OpenSSL::Digest.new('sha256').block_length.should == SHA256Constants::BlockLength
+    end
+
+    it "returns a SHA384 block length" do
+      OpenSSL::Digest.new('sha384').block_length.should == SHA384Constants::BlockLength
+    end
+
+    it "returns a SHA512 block length" do
+      OpenSSL::Digest.new('sha512').block_length.should == SHA512Constants::BlockLength
+    end
+  end
+
+  context "when the digest object is created via a subclass" do
+    it "returns a SHA1 block length" do
+      OpenSSL::Digest::SHA1.new.block_length.should == SHA1Constants::BlockLength
+    end
+
+    it "returns a SHA256 block length" do
+      OpenSSL::Digest::SHA256.new.block_length.should == SHA256Constants::BlockLength
+    end
+
+    it "returns a SHA384 block length" do
+      OpenSSL::Digest::SHA384.new.block_length.should == SHA384Constants::BlockLength
+    end
+
+    it "returns a SHA512 block length" do
+      OpenSSL::Digest::SHA512.new.block_length.should == SHA512Constants::BlockLength
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/digest_length_spec.rb b/spec/ruby/library/openssl/digest/digest_length_spec.rb
new file mode 100644
index 0000000000..37d1cba9a7
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/digest_length_spec.rb
@@ -0,0 +1,44 @@
+require_relative '../../../spec_helper'
+require_relative '../../../library/digest/sha1/shared/constants'
+require_relative '../../../library/digest/sha256/shared/constants'
+require_relative '../../../library/digest/sha384/shared/constants'
+require_relative '../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe "OpenSSL::Digest#digest_length" do
+  context "when the digest object is created via a name argument" do
+    it "returns a SHA1 digest length" do
+      OpenSSL::Digest.new('sha1').digest_length.should == SHA1Constants::DigestLength
+    end
+
+    it "returns a SHA256 digest length" do
+      OpenSSL::Digest.new('sha256').digest_length.should == SHA256Constants::DigestLength
+    end
+
+    it "returns a SHA384 digest length" do
+      OpenSSL::Digest.new('sha384').digest_length.should == SHA384Constants::DigestLength
+    end
+
+    it "returns a SHA512 digest length" do
+      OpenSSL::Digest.new('sha512').digest_length.should == SHA512Constants::DigestLength
+    end
+  end
+
+  context "when the digest object is created via a subclass" do
+    it "returns a SHA1 digest length" do
+      OpenSSL::Digest::SHA1.new.digest_length.should == SHA1Constants::DigestLength
+    end
+
+    it "returns a SHA256 digest length" do
+      OpenSSL::Digest::SHA256.new.digest_length.should == SHA256Constants::DigestLength
+    end
+
+    it "returns a SHA384 digest length" do
+      OpenSSL::Digest::SHA384.new.digest_length.should == SHA384Constants::DigestLength
+    end
+
+    it "returns a SHA512 digest length" do
+      OpenSSL::Digest::SHA512.new.digest_length.should == SHA512Constants::DigestLength
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/digest_spec.rb b/spec/ruby/library/openssl/digest/digest_spec.rb
new file mode 100644
index 0000000000..cf27d01b6d
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/digest_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../../spec_helper'
+require_relative '../../../library/digest/sha1/shared/constants'
+require_relative '../../../library/digest/sha256/shared/constants'
+require_relative '../../../library/digest/sha384/shared/constants'
+require_relative '../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe "OpenSSL::Digest class methods" do
+  describe ".digest" do
+    it "returns a SHA1 digest" do
+      OpenSSL::Digest.digest('sha1', SHA1Constants::Contents).should == SHA1Constants::Digest
+    end
+
+    it "returns a SHA256 digest" do
+      OpenSSL::Digest.digest('sha256', SHA256Constants::Contents).should == SHA256Constants::Digest
+    end
+
+    it "returns a SHA384 digest" do
+      OpenSSL::Digest.digest('sha384', SHA384Constants::Contents).should == SHA384Constants::Digest
+    end
+
+    it "returns a SHA512 digest" do
+      OpenSSL::Digest.digest('sha512', SHA512Constants::Contents).should == SHA512Constants::Digest
+    end
+  end
+
+  describe ".hexdigest" do
+    it "returns a SHA1 hexdigest" do
+      OpenSSL::Digest.hexdigest('sha1', SHA1Constants::Contents).should == SHA1Constants::Hexdigest
+    end
+
+    it "returns a SHA256 hexdigest" do
+      OpenSSL::Digest.hexdigest('sha256', SHA256Constants::Contents).should == SHA256Constants::Hexdigest
+    end
+
+    it "returns a SHA384 hexdigest" do
+      OpenSSL::Digest.hexdigest('sha384', SHA384Constants::Contents).should == SHA384Constants::Hexdigest
+    end
+
+    it "returns a SHA512 hexdigest" do
+      OpenSSL::Digest.hexdigest('sha512', SHA512Constants::Contents).should == SHA512Constants::Hexdigest
+    end
+  end
+
+  describe ".base64digest" do
+    it "returns a SHA1 base64digest" do
+      OpenSSL::Digest.base64digest('sha1', SHA1Constants::Contents).should == SHA1Constants::Base64digest
+    end
+
+    it "returns a SHA256 base64digest" do
+      OpenSSL::Digest.base64digest('sha256', SHA256Constants::Contents).should == SHA256Constants::Base64digest
+    end
+
+    it "returns a SHA384 base64digest" do
+      OpenSSL::Digest.base64digest('sha384', SHA384Constants::Contents).should == SHA384Constants::Base64digest
+    end
+
+    it "returns a SHA512 base64digest" do
+      OpenSSL::Digest.base64digest('sha512', SHA512Constants::Contents).should == SHA512Constants::Base64digest
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/initialize_spec.rb b/spec/ruby/library/openssl/digest/initialize_spec.rb
new file mode 100644
index 0000000000..e24ab51d14
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/initialize_spec.rb
@@ -0,0 +1,137 @@
+require_relative '../../../spec_helper'
+require_relative '../../../library/digest/sha1/shared/constants'
+require_relative '../../../library/digest/sha256/shared/constants'
+require_relative '../../../library/digest/sha384/shared/constants'
+require_relative '../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe "OpenSSL::Digest#initialize" do
+  describe "can be called with a digest name" do
+    it "returns a SHA1 object" do
+      OpenSSL::Digest.new("sha1").name.should == "SHA1"
+    end
+
+    it "returns a SHA256 object" do
+      OpenSSL::Digest.new("sha256").name.should == "SHA256"
+    end
+
+    it "returns a SHA384 object" do
+      OpenSSL::Digest.new("sha384").name.should == "SHA384"
+    end
+
+    it "returns a SHA512 object" do
+      OpenSSL::Digest.new("sha512").name.should ==  "SHA512"
+    end
+
+    version_is OpenSSL::VERSION, "4.0.0" do
+      it "throws an error when called with an unknown digest" do
+        -> { OpenSSL::Digest.new("wd40") }.should.raise(OpenSSL::Digest::DigestError, /wd40/)
+      end
+    end
+
+    it "cannot be called with a symbol" do
+      -> { OpenSSL::Digest.new(:SHA1) }.should.raise(TypeError)
+    end
+  end
+
+  describe "can be called with a digest object" do
+    it "returns a SHA1 object" do
+      OpenSSL::Digest.new(OpenSSL::Digest::SHA1.new).name.should == "SHA1"
+    end
+
+    it "returns a SHA256 object" do
+      OpenSSL::Digest.new(OpenSSL::Digest::SHA256.new).name.should == "SHA256"
+    end
+
+    it "returns a SHA384 object" do
+      OpenSSL::Digest.new(OpenSSL::Digest::SHA384.new).name.should == "SHA384"
+    end
+
+    it "returns a SHA512 object" do
+      OpenSSL::Digest.new(OpenSSL::Digest::SHA512.new).name.should ==  "SHA512"
+    end
+
+    it "ignores the state of the digest object" do
+      sha1 = OpenSSL::Digest.new('sha1', SHA1Constants::Contents)
+      OpenSSL::Digest.new(sha1).digest.should == SHA1Constants::BlankDigest
+    end
+  end
+
+  it "cannot be called with a digest class" do
+    -> { OpenSSL::Digest.new(OpenSSL::Digest::SHA1) }.should.raise(TypeError)
+  end
+
+  context "when called without an initial String argument" do
+    it "returns a SHA1 digest" do
+      OpenSSL::Digest.new("sha1").digest.should == SHA1Constants::BlankDigest
+    end
+
+    it "returns a SHA256 digest" do
+      OpenSSL::Digest.new("sha256").digest.should == SHA256Constants::BlankDigest
+    end
+
+    it "returns a SHA384 digest" do
+      OpenSSL::Digest.new("sha384").digest.should == SHA384Constants::BlankDigest
+    end
+
+    it "returns a SHA512 digest" do
+      OpenSSL::Digest.new("sha512").digest.should == SHA512Constants::BlankDigest
+    end
+  end
+
+  context "when called with an initial String argument" do
+    it "returns a SHA1 digest of that argument" do
+      OpenSSL::Digest.new("sha1", SHA1Constants::Contents).digest.should == SHA1Constants::Digest
+    end
+
+    it "returns a SHA256 digest of that argument" do
+      OpenSSL::Digest.new("sha256", SHA256Constants::Contents).digest.should == SHA256Constants::Digest
+    end
+
+    it "returns a SHA384 digest of that argument" do
+      OpenSSL::Digest.new("sha384", SHA384Constants::Contents).digest.should == SHA384Constants::Digest
+    end
+
+    it "returns a SHA512 digest of that argument" do
+      OpenSSL::Digest.new("sha512", SHA512Constants::Contents).digest.should == SHA512Constants::Digest
+    end
+  end
+
+  context "can be called on subclasses" do
+    describe "can be called without an initial String argument on subclasses" do
+      it "returns a SHA1 digest" do
+        OpenSSL::Digest::SHA1.new.digest.should == SHA1Constants::BlankDigest
+      end
+
+      it "returns a SHA256 digest" do
+        OpenSSL::Digest::SHA256.new.digest.should == SHA256Constants::BlankDigest
+      end
+
+      it "returns a SHA384 digest" do
+        OpenSSL::Digest::SHA384.new.digest.should == SHA384Constants::BlankDigest
+      end
+
+      it "returns a SHA512 digest" do
+        OpenSSL::Digest::SHA512.new.digest.should == SHA512Constants::BlankDigest
+      end
+    end
+
+    describe "can be called with an initial String argument on subclasses" do
+      it "returns a SHA1 digest" do
+        OpenSSL::Digest::SHA1.new(SHA1Constants::Contents).digest.should == SHA1Constants::Digest
+      end
+
+      it "returns a SHA256 digest" do
+        OpenSSL::Digest::SHA256.new(SHA256Constants::Contents).digest.should == SHA256Constants::Digest
+      end
+
+      it "returns a SHA384 digest" do
+        OpenSSL::Digest::SHA384.new(SHA384Constants::Contents).digest.should == SHA384Constants::Digest
+      end
+
+      it "returns a SHA512 digest" do
+        OpenSSL::Digest::SHA512.new(SHA512Constants::Contents).digest.should == SHA512Constants::Digest
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/name_spec.rb b/spec/ruby/library/openssl/digest/name_spec.rb
new file mode 100644
index 0000000000..b379f35c1c
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/name_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../../spec_helper'
+require 'openssl'
+
+describe "OpenSSL::Digest#name" do
+  it "returns the name of digest" do
+    OpenSSL::Digest.new('SHA1').name.should == 'SHA1'
+  end
+
+  it "converts the name to the internal representation of OpenSSL" do
+    OpenSSL::Digest.new('sha1').name.should == 'SHA1'
+  end
+
+  it "works on subclasses too" do
+    OpenSSL::Digest::SHA1.new.name.should == 'SHA1'
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/reset_spec.rb b/spec/ruby/library/openssl/digest/reset_spec.rb
new file mode 100644
index 0000000000..c19bf46633
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/reset_spec.rb
@@ -0,0 +1,36 @@
+require_relative '../../../spec_helper'
+require_relative '../../../library/digest/sha1/shared/constants'
+require_relative '../../../library/digest/sha256/shared/constants'
+require_relative '../../../library/digest/sha384/shared/constants'
+require_relative '../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe "OpenSSL::Digest#reset" do
+  it "works for a SHA1 digest" do
+    digest = OpenSSL::Digest.new('sha1', SHA1Constants::Contents)
+    digest.reset
+    digest.update(SHA1Constants::Contents)
+    digest.digest.should == SHA1Constants::Digest
+  end
+
+  it "works for a SHA256 digest" do
+    digest = OpenSSL::Digest.new('sha256', SHA256Constants::Contents)
+    digest.reset
+    digest.update(SHA256Constants::Contents)
+    digest.digest.should == SHA256Constants::Digest
+  end
+
+  it "works for a SHA384 digest" do
+    digest = OpenSSL::Digest.new('sha384', SHA384Constants::Contents)
+    digest.reset
+    digest.update(SHA384Constants::Contents)
+    digest.digest.should == SHA384Constants::Digest
+  end
+
+  it "works for a SHA512 digest" do
+    digest = OpenSSL::Digest.new('sha512', SHA512Constants::Contents)
+    digest.reset
+    digest.update(SHA512Constants::Contents)
+    digest.digest.should == SHA512Constants::Digest
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/shared/update.rb b/spec/ruby/library/openssl/digest/shared/update.rb
new file mode 100644
index 0000000000..37277c945d
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/shared/update.rb
@@ -0,0 +1,123 @@
+require_relative '../../../../library/digest/sha1/shared/constants'
+require_relative '../../../../library/digest/sha256/shared/constants'
+require_relative '../../../../library/digest/sha384/shared/constants'
+require_relative '../../../../library/digest/sha512/shared/constants'
+require 'openssl'
+
+describe :openssl_digest_update, shared: true do
+  context "when given input as a single string" do
+    it "returns a SHA1 digest" do
+      digest = OpenSSL::Digest.new('sha1')
+      digest.send(@method, SHA1Constants::Contents)
+      digest.digest.should == SHA1Constants::Digest
+    end
+
+    it "returns a SHA256 digest" do
+      digest = OpenSSL::Digest.new('sha256')
+      digest.send(@method, SHA256Constants::Contents)
+      digest.digest.should == SHA256Constants::Digest
+    end
+
+    it "returns a SHA384 digest" do
+      digest = OpenSSL::Digest.new('sha384')
+      digest.send(@method, SHA384Constants::Contents)
+      digest.digest.should == SHA384Constants::Digest
+    end
+
+    it "returns a SHA512 digest" do
+      digest = OpenSSL::Digest.new('sha512')
+      digest.send(@method, SHA512Constants::Contents)
+      digest.digest.should == SHA512Constants::Digest
+    end
+  end
+
+  context "when given input as multiple smaller substrings" do
+    it "returns a SHA1 digest" do
+      digest = OpenSSL::Digest.new('sha1')
+      SHA1Constants::Contents.each_char { |b| digest.send(@method, b) }
+      digest.digest.should == SHA1Constants::Digest
+    end
+
+    it "returns a SHA256 digest" do
+      digest = OpenSSL::Digest.new('sha256')
+      SHA256Constants::Contents.each_char { |b| digest.send(@method, b) }
+      digest.digest.should == SHA256Constants::Digest
+    end
+
+    it "returns a SHA384 digest" do
+      digest = OpenSSL::Digest.new('sha384')
+      SHA384Constants::Contents.each_char { |b| digest.send(@method, b) }
+      digest.digest.should == SHA384Constants::Digest
+    end
+
+    it "returns a SHA512 digest" do
+      digest = OpenSSL::Digest.new('sha512')
+      SHA512Constants::Contents.each_char { |b| digest.send(@method, b) }
+      digest.digest.should == SHA512Constants::Digest
+    end
+  end
+
+  context "when input is not a String and responds to #to_str" do
+    it "returns a SHA1 digest" do
+      str = mock('str')
+      str.should_receive(:to_str).and_return(SHA1Constants::Contents)
+      digest = OpenSSL::Digest.new('sha1')
+      digest.send(@method, str)
+      digest.digest.should == SHA1Constants::Digest
+    end
+
+    it "returns a SHA256 digest" do
+      str = mock('str')
+      str.should_receive(:to_str).and_return(SHA256Constants::Contents)
+      digest = OpenSSL::Digest.new('sha256')
+      digest.send(@method, str)
+      digest.digest.should == SHA256Constants::Digest
+    end
+
+    it "returns a SHA384 digest" do
+      str = mock('str')
+      str.should_receive(:to_str).and_return(SHA384Constants::Contents)
+      digest = OpenSSL::Digest.new('sha384')
+      digest.send(@method, str)
+      digest.digest.should == SHA384Constants::Digest
+    end
+
+    it "returns a SHA512 digest" do
+      str = mock('str')
+      str.should_receive(:to_str).and_return(SHA512Constants::Contents)
+      digest = OpenSSL::Digest.new('sha512')
+      digest.send(@method, str)
+      digest.digest.should == SHA512Constants::Digest
+    end
+  end
+
+  context "when input is not a String and does not respond to #to_str" do
+    it "raises a TypeError with SHA1" do
+      digest = OpenSSL::Digest.new('sha1')
+      -> {
+        digest.send(@method, Object.new)
+      }.should.raise(TypeError, 'no implicit conversion of Object into String')
+    end
+
+    it "raises a TypeError with SHA256" do
+      digest = OpenSSL::Digest.new('sha256')
+      -> {
+        digest.send(@method, Object.new)
+      }.should.raise(TypeError, 'no implicit conversion of Object into String')
+    end
+
+    it "raises a TypeError with SHA384" do
+      digest = OpenSSL::Digest.new('sha384')
+      -> {
+        digest.send(@method, Object.new)
+      }.should.raise(TypeError, 'no implicit conversion of Object into String')
+    end
+
+    it "raises a TypeError with SHA512" do
+      digest = OpenSSL::Digest.new('sha512')
+      -> {
+        digest.send(@method, Object.new)
+      }.should.raise(TypeError, 'no implicit conversion of Object into String')
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/digest/update_spec.rb b/spec/ruby/library/openssl/digest/update_spec.rb
new file mode 100644
index 0000000000..3a90b06c6b
--- /dev/null
+++ b/spec/ruby/library/openssl/digest/update_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../../spec_helper'
+require_relative 'shared/update'
+
+describe "OpenSSL::Digest#update" do
+  it_behaves_like :openssl_digest_update, :update
+end
diff --git a/spec/ruby/library/openssl/fixed_length_secure_compare_spec.rb b/spec/ruby/library/openssl/fixed_length_secure_compare_spec.rb
new file mode 100644
index 0000000000..cc638e1f0d
--- /dev/null
+++ b/spec/ruby/library/openssl/fixed_length_secure_compare_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require 'openssl'
+
+describe "OpenSSL.fixed_length_secure_compare" do
+  it "returns true for two strings with the same content" do
+    input1 = "the quick brown fox jumps over the lazy dog"
+    input2 = "the quick brown fox jumps over the lazy dog"
+    OpenSSL.fixed_length_secure_compare(input1, input2).should == true
+  end
+
+  it "returns false for two strings of equal size with different content" do
+    input1 = "the quick brown fox jumps over the lazy dog"
+    input2 = "the lazy dog jumps over the quick brown fox"
+    OpenSSL.fixed_length_secure_compare(input1, input2).should == false
+  end
+
+  it "converts both arguments to strings using #to_str" do
+    input1 = mock("input1")
+    input1.should_receive(:to_str).and_return("the quick brown fox jumps over the lazy dog")
+    input2 = mock("input2")
+    input2.should_receive(:to_str).and_return("the quick brown fox jumps over the lazy dog")
+    OpenSSL.fixed_length_secure_compare(input1, input2).should == true
+  end
+
+  it "does not accept arguments that are not string and cannot be coerced into strings" do
+    -> {
+      OpenSSL.fixed_length_secure_compare("input1", :input2)
+    }.should.raise(TypeError, 'no implicit conversion of Symbol into String')
+
+    -> {
+      OpenSSL.fixed_length_secure_compare(Object.new, "input2")
+    }.should.raise(TypeError, 'no implicit conversion of Object into String')
+  end
+
+  it "raises an ArgumentError for two strings of different size" do
+    input1 = "the quick brown fox jumps over the lazy dog"
+    input2 = "the quick brown fox"
+    -> {
+      OpenSSL.fixed_length_secure_compare(input1, input2)
+    }.should.raise(ArgumentError, 'inputs must be of equal length')
+  end
+end
diff --git a/spec/ruby/library/openssl/hmac/digest_spec.rb b/spec/ruby/library/openssl/hmac/digest_spec.rb
index 22bc7023bc..03ed136e64 100644
--- a/spec/ruby/library/openssl/hmac/digest_spec.rb
+++ b/spec/ruby/library/openssl/hmac/digest_spec.rb
@@ -4,7 +4,7 @@ require 'openssl'
 
 describe "OpenSSL::HMAC.digest" do
   it "returns an SHA1 digest" do
-    cur_digest = OpenSSL::Digest::SHA1.new
+    cur_digest = OpenSSL::Digest.new("SHA1")
     cur_digest.digest.should == HMACConstants::BlankSHA1Digest
     digest = OpenSSL::HMAC.digest(cur_digest,
                                         HMACConstants::Key,
diff --git a/spec/ruby/library/openssl/hmac/hexdigest_spec.rb b/spec/ruby/library/openssl/hmac/hexdigest_spec.rb
index 7f73b2db09..3508c1bbd7 100644
--- a/spec/ruby/library/openssl/hmac/hexdigest_spec.rb
+++ b/spec/ruby/library/openssl/hmac/hexdigest_spec.rb
@@ -4,7 +4,7 @@ require 'openssl'
 
 describe "OpenSSL::HMAC.hexdigest" do
   it "returns an SHA1 hex digest" do
-    cur_digest = OpenSSL::Digest::SHA1.new
+    cur_digest = OpenSSL::Digest.new("SHA1")
     cur_digest.hexdigest.should == HMACConstants::BlankSHA1HexDigest
     hexdigest = OpenSSL::HMAC.hexdigest(cur_digest,
                                         HMACConstants::Key,
diff --git a/spec/ruby/library/openssl/kdf/pbkdf2_hmac_spec.rb b/spec/ruby/library/openssl/kdf/pbkdf2_hmac_spec.rb
new file mode 100644
index 0000000000..2558dbb9ec
--- /dev/null
+++ b/spec/ruby/library/openssl/kdf/pbkdf2_hmac_spec.rb
@@ -0,0 +1,162 @@
+require_relative '../../../spec_helper'
+require 'openssl'
+
+describe "OpenSSL::KDF.pbkdf2_hmac" do
+  before :each do
+    @defaults = {
+      salt: "\x00".b * 16,
+      iterations: 20_000,
+      length: 16,
+      hash: "sha1"
+    }
+  end
+
+  it "creates the same value with the same input" do
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "supports nullbytes embedded in the password" do
+    key = OpenSSL::KDF.pbkdf2_hmac("sec\x00ret".b, **@defaults)
+    key.should == "\xB9\x7F\xB0\xC2\th\xC8<\x86\xF3\x94Ij7\xEF\xF1".b
+  end
+
+  it "coerces the password into a String using #to_str" do
+    pass = mock("pass")
+    pass.should_receive(:to_str).and_return("secret")
+    key = OpenSSL::KDF.pbkdf2_hmac(pass, **@defaults)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "coerces the salt into a String using #to_str" do
+    salt = mock("salt")
+    salt.should_receive(:to_str).and_return("\x00".b * 16)
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, salt: salt)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "coerces the iterations into an Integer using #to_int" do
+    iterations = mock("iterations")
+    iterations.should_receive(:to_int).and_return(20_000)
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, iterations: iterations)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "coerces the length into an Integer using #to_int" do
+    length = mock("length")
+    length.should_receive(:to_int).and_return(16)
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, length: length)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "accepts a OpenSSL::Digest object as hash" do
+    hash = OpenSSL::Digest.new("sha1")
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, hash: hash)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0".b
+  end
+
+  it "accepts an empty password" do
+    key = OpenSSL::KDF.pbkdf2_hmac("", **@defaults)
+    key.should == "k\x9F-\xB1\xF7\x9A\v\xA1(C\xF9\x85!P\xEF\x8C".b
+  end
+
+  it "accepts an empty salt" do
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, salt: "")
+    key.should == "\xD5f\xE5\xEA\xF91\x1D\xD3evD\xED\xDB\xE80\x80".b
+  end
+
+  it "accepts an empty length" do
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, length: 0)
+    key.should.empty?
+  end
+
+  it "accepts an arbitrary length" do
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, length: 19)
+    key.should == "!\x99+\xF0^\xD0\x8BM\x158\xC4\xAC\x9C\xF1\xF0\xE0\xCF\xBB\x7F".b
+  end
+
+  it "accepts any hash function known to OpenSSL" do
+    key = OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, hash: "sha512")
+    key.should == "N\x12}D\xCE\x99\xDBC\x8E\xEC\xAAr\xEA1\xDF\xFF".b
+  end
+
+  it "raises a TypeError when password is not a String and does not respond to #to_str" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac(Object.new, **@defaults)
+    }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises a TypeError when salt is not a String and does not respond to #to_str" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, salt: Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises a TypeError when iterations is not an Integer and does not respond to #to_int" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, iterations: Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+  end
+
+  it "raises a TypeError when length is not an Integer and does not respond to #to_int" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, length: Object.new)
+    }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+  end
+
+  it "raises a TypeError when hash is neither a String nor an OpenSSL::Digest" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, hash: Object.new)
+    }.should.raise(TypeError)
+  end
+
+  version_is OpenSSL::VERSION, "4.0.0" do
+    it "raises a OpenSSL::Digest::DigestError for unknown digest algorithms" do
+      -> {
+        OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, hash: "wd40")
+      }.should.raise(OpenSSL::Digest::DigestError, /wd40/)
+    end
+  end
+
+  it "treats salt as a required keyword" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults.except(:salt))
+    }.should.raise(ArgumentError, 'missing keyword: :salt')
+  end
+
+  it "treats iterations as a required keyword" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults.except(:iterations))
+    }.should.raise(ArgumentError, 'missing keyword: :iterations')
+  end
+
+  it "treats length as a required keyword" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults.except(:length))
+    }.should.raise(ArgumentError, 'missing keyword: :length')
+  end
+
+  it "treats hash as a required keyword" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults.except(:hash))
+    }.should.raise(ArgumentError, 'missing keyword: :hash')
+  end
+
+  it "treats all keywords as required" do
+    -> {
+      OpenSSL::KDF.pbkdf2_hmac("secret")
+    }.should.raise(ArgumentError, 'missing keywords: :salt, :iterations, :length, :hash')
+  end
+
+  guard -> { OpenSSL::OPENSSL_VERSION_NUMBER >= 0x30000000 } do
+    it "raises an OpenSSL::KDF::KDFError for 0 or less iterations" do
+      -> {
+        OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, iterations: 0)
+      }.should.raise(OpenSSL::KDF::KDFError, "PKCS5_PBKDF2_HMAC: invalid iteration count")
+
+      -> {
+        OpenSSL::KDF.pbkdf2_hmac("secret", **@defaults, iterations: -1)
+      }.should.raise(OpenSSL::KDF::KDFError, /PKCS5_PBKDF2_HMAC/)
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/kdf/scrypt_spec.rb b/spec/ruby/library/openssl/kdf/scrypt_spec.rb
new file mode 100644
index 0000000000..c00f91bb5b
--- /dev/null
+++ b/spec/ruby/library/openssl/kdf/scrypt_spec.rb
@@ -0,0 +1,210 @@
+require_relative '../../../spec_helper'
+require 'openssl'
+
+# LibreSSL seems not to support scrypt
+guard -> { OpenSSL::OPENSSL_VERSION.start_with?('OpenSSL') and OpenSSL::OPENSSL_VERSION_NUMBER >= 0x10100000 } do
+  describe "OpenSSL::KDF.scrypt" do
+    before :each do
+      @defaults = {
+        salt: "\x00".b * 16,
+        N: 2**14,
+        r: 8,
+        p: 1,
+        length: 32
+      }
+    end
+
+    it "creates the same value with the same input" do
+      key = OpenSSL::KDF.scrypt("secret", **@defaults)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "supports nullbytes embedded into the password" do
+      key = OpenSSL::KDF.scrypt("sec\x00ret".b, **@defaults)
+      key.should == "\xF9\xA4\xA0\xF1p\xF4\xF0\xCAT\xB4v\xEB\r7\x88N\xF7\x15]Ns\xFCwt4a\xC9\xC6\xA7\x13\x81&".b
+    end
+
+    it "coerces the password into a String using #to_str" do
+      pass = mock("pass")
+      pass.should_receive(:to_str).and_return("secret")
+      key = OpenSSL::KDF.scrypt(pass, **@defaults)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "coerces the salt into a String using #to_str" do
+      salt = mock("salt")
+      salt.should_receive(:to_str).and_return("\x00".b * 16)
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, salt: salt)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "coerces the N into an Integer using #to_int" do
+      n = mock("N")
+      n.should_receive(:to_int).and_return(2**14)
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, N: n)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "coerces the r into an Integer using #to_int" do
+      r = mock("r")
+      r.should_receive(:to_int).and_return(8)
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, r: r)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "coerces the p into an Integer using #to_int" do
+      p = mock("p")
+      p.should_receive(:to_int).and_return(1)
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, p: p)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "coerces the length into an Integer using #to_int" do
+      length = mock("length")
+      length.should_receive(:to_int).and_return(32)
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, length: length)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D\x17}\xF2\x84T\xD4)\xC2>\xFE\x93\xE3\xF4".b
+    end
+
+    it "accepts an empty password" do
+      key = OpenSSL::KDF.scrypt("", **@defaults)
+      key.should == "\xAA\xFC\xF5^E\x94v\xFFk\xE6\xF0vR\xE7\x13\xA7\xF5\x15'\x9A\xE4C\x9Dn\x18F_E\xD2\v\e\xB3".b
+    end
+
+    it "accepts an empty salt" do
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, salt: "")
+      key.should == "\x96\xACDl\xCB3/aN\xB0F\x8A#\xD7\x92\xD2O\x1E\v\xBB\xCE\xC0\xAA\xB9\x0F]\xB09\xEA8\xDD\e".b
+    end
+
+    it "accepts a zero length" do
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, length: 0)
+      key.should.empty?
+    end
+
+    it "accepts an arbitrary length" do
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, length: 19)
+      key.should == "h\xB2k\xDF]\xDA\xE1.-(\xCF\xAC\x91D\x8F\xC2a\x9C\x9D".b
+    end
+
+    it "raises a TypeError when password is not a String and does not respond to #to_str" do
+      -> {
+        OpenSSL::KDF.scrypt(Object.new, **@defaults)
+      }.should.raise(TypeError, "no implicit conversion of Object into String")
+    end
+
+    it "raises a TypeError when salt is not a String and does not respond to #to_str" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, salt: Object.new)
+      }.should.raise(TypeError, "no implicit conversion of Object into String")
+    end
+
+    it "raises a TypeError when N is not an Integer and does not respond to #to_int" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, N: Object.new)
+      }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+
+    it "raises a TypeError when r is not an Integer and does not respond to #to_int" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, r: Object.new)
+      }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+
+    it "raises a TypeError when p is not an Integer and does not respond to #to_int" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, p: Object.new)
+      }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+
+    it "raises a TypeError when length is not an Integer and does not respond to #to_int" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, length: Object.new)
+      }.should.raise(TypeError, "no implicit conversion of Object into Integer")
+    end
+
+    it "treats salt as a required keyword" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults.except(:salt))
+      }.should.raise(ArgumentError, 'missing keyword: :salt')
+    end
+
+    it "treats N as a required keyword" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults.except(:N))
+      }.should.raise(ArgumentError, 'missing keyword: :N')
+    end
+
+    it "treats r as a required keyword" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults.except(:r))
+      }.should.raise(ArgumentError, 'missing keyword: :r')
+    end
+
+    it "treats p as a required keyword" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults.except(:p))
+      }.should.raise(ArgumentError, 'missing keyword: :p')
+    end
+
+    it "treats length as a required keyword" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults.except(:length))
+      }.should.raise(ArgumentError, 'missing keyword: :length')
+    end
+
+    it "treats all keywords as required" do
+      -> {
+        OpenSSL::KDF.scrypt("secret")
+      }.should.raise(ArgumentError, 'missing keywords: :salt, :N, :r, :p, :length')
+    end
+
+    it "requires N to be a power of 2" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, N: 2**14 - 1)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+    end
+
+    it "requires N to be at least 2" do
+      key = OpenSSL::KDF.scrypt("secret", **@defaults, N: 2)
+      key.should == "\x06A$a\xA9!\xBE\x01\x85\xA7\x18\xBCEa\x82\xC5\xFEl\x93\xAB\xBD\xF7\x8B\x84\v\xFC\eN\xEBQ\xE6\xD2".b
+
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, N: 1)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, N: 0)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, N: -1)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+    end
+
+    it "requires r to be positive" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, r: 0)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, r: -1)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+    end
+
+    it "requires p to be positive" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, p: 0)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, p: -1)
+      }.should.raise(OpenSSL::KDF::KDFError, /EVP_PBE_scrypt/)
+    end
+
+    it "requires length to be not negative" do
+      -> {
+        OpenSSL::KDF.scrypt("secret", **@defaults, length: -1)
+      }.should.raise(ArgumentError, "negative string size (or size too big)")
+    end
+  end
+end
diff --git a/spec/ruby/library/openssl/random/shared/random_bytes.rb b/spec/ruby/library/openssl/random/shared/random_bytes.rb
index 037f10d409..4d1751e57e 100644
--- a/spec/ruby/library/openssl/random/shared/random_bytes.rb
+++ b/spec/ruby/library/openssl/random/shared/random_bytes.rb
@@ -1,11 +1,11 @@
 require_relative '../../../../spec_helper'
 require 'openssl'
 
-describe :openssl_random_bytes, shared: true do |cmd|
+describe :openssl_random_bytes, shared: true do
   it "generates a random binary string of specified length" do
     (1..64).each do |idx|
       bytes = OpenSSL::Random.send(@method, idx)
-      bytes.should be_kind_of(String)
+      bytes.should.is_a?(String)
       bytes.length.should == idx
     end
   end
@@ -24,6 +24,6 @@ describe :openssl_random_bytes, shared: true do |cmd|
   it "raises ArgumentError on negative arguments" do
     -> {
       OpenSSL::Random.send(@method, -1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/openssl/secure_compare_spec.rb b/spec/ruby/library/openssl/secure_compare_spec.rb
new file mode 100644
index 0000000000..ce2a4a0d43
--- /dev/null
+++ b/spec/ruby/library/openssl/secure_compare_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../../spec_helper'
+require 'openssl'
+
+describe "OpenSSL.secure_compare" do
+  it "returns true for two strings with the same content" do
+    input1 = "the quick brown fox jumps over the lazy dog"
+    input2 = "the quick brown fox jumps over the lazy dog"
+    OpenSSL.secure_compare(input1, input2).should == true
+  end
+
+  it "returns false for two strings with different content" do
+    input1 = "the quick brown fox jumps over the lazy dog"
+    input2 = "the lazy dog jumps over the quick brown fox"
+    OpenSSL.secure_compare(input1, input2).should == false
+  end
+
+  it "converts both arguments to strings using #to_str, but adds equality check for the original objects" do
+    input1 = mock("input1")
+    input1.should_receive(:to_str).and_return("the quick brown fox jumps over the lazy dog")
+    input2 = mock("input2")
+    input2.should_receive(:to_str).and_return("the quick brown fox jumps over the lazy dog")
+    OpenSSL.secure_compare(input1, input2).should == false
+
+    input = mock("input")
+    input.should_receive(:to_str).twice.and_return("the quick brown fox jumps over the lazy dog")
+    OpenSSL.secure_compare(input, input).should == true
+  end
+
+  it "does not accept arguments that are not string and cannot be coerced into strings" do
+    -> {
+      OpenSSL.secure_compare("input1", :input2)
+    }.should.raise(TypeError, 'no implicit conversion of Symbol into String')
+
+    -> {
+      OpenSSL.secure_compare(Object.new, "input2")
+    }.should.raise(TypeError, 'no implicit conversion of Object into String')
+  end
+end
diff --git a/spec/ruby/library/openssl/shared/constants.rb b/spec/ruby/library/openssl/shared/constants.rb
index 0bed4156a1..836f75011b 100644
--- a/spec/ruby/library/openssl/shared/constants.rb
+++ b/spec/ruby/library/openssl/shared/constants.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 module HMACConstants
 
   Contents = "Ipsum is simply dummy text of the printing and typesetting industry. \nLorem Ipsum has been the industrys standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. \nIt has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. \nIt was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum."
diff --git a/spec/ruby/library/openssl/x509/name/parse_spec.rb b/spec/ruby/library/openssl/x509/name/parse_spec.rb
index 6624161d83..84e3d442f6 100644
--- a/spec/ruby/library/openssl/x509/name/parse_spec.rb
+++ b/spec/ruby/library/openssl/x509/name/parse_spec.rb
@@ -37,12 +37,12 @@ describe "OpenSSL::X509::Name.parse" do
   it "raises TypeError if the given string contains no key/value pairs" do
     -> do
       OpenSSL::X509::Name.parse("hello")
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it "raises OpenSSL::X509::NameError if the given string contains invalid keys" do
     -> do
       OpenSSL::X509::Name.parse("hello=goodbye")
-    end.should raise_error(OpenSSL::X509::NameError)
+    end.should.raise(OpenSSL::X509::NameError)
   end
 end
diff --git a/spec/ruby/library/openssl/x509/store/verify_spec.rb b/spec/ruby/library/openssl/x509/store/verify_spec.rb
new file mode 100644
index 0000000000..6a6a53d992
--- /dev/null
+++ b/spec/ruby/library/openssl/x509/store/verify_spec.rb
@@ -0,0 +1,78 @@
+require_relative '../../../../spec_helper'
+require 'openssl'
+
+describe "OpenSSL::X509::Store#verify" do
+  it "returns true for valid certificate" do
+    key = OpenSSL::PKey::RSA.new 2048
+    cert = OpenSSL::X509::Certificate.new
+    cert.version = 2
+    cert.serial = 1
+    cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=truffleruby/CN=TruffleRuby CA"
+    cert.issuer = cert.subject
+    cert.public_key = key.public_key
+    cert.not_before = Time.now - 10
+    cert.not_after = cert.not_before + 365 * 24 * 60 * 60
+    cert.sign key, OpenSSL::Digest.new('SHA256')
+    store = OpenSSL::X509::Store.new
+    store.add_cert(cert)
+    [store.verify(cert), store.error, store.error_string].should == [true, 0, "ok"]
+  end
+
+  it "returns false for an expired certificate" do
+    key = OpenSSL::PKey::RSA.new 2048
+    cert = OpenSSL::X509::Certificate.new
+    cert.version = 2
+    cert.serial = 1
+    cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=truffleruby/CN=TruffleRuby CA"
+    cert.issuer = cert.subject
+    cert.public_key = key.public_key
+    cert.not_before = Time.now - 10
+    cert.not_after = Time.now - 5
+    cert.sign key, OpenSSL::Digest.new('SHA256')
+    store = OpenSSL::X509::Store.new
+    store.add_cert(cert)
+    store.verify(cert).should == false
+  end
+
+  it "returns false for an expired root certificate" do
+    root_key = OpenSSL::PKey::RSA.new 2048
+    root_cert = OpenSSL::X509::Certificate.new
+    root_cert.version = 2
+    root_cert.serial = 1
+    root_cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=truffleruby/CN=TruffleRuby CA"
+    root_cert.issuer = root_cert.subject
+    root_cert.public_key = root_key.public_key
+    root_cert.not_before = Time.now - 10
+    root_cert.not_after = Time.now - 5
+    ef = OpenSSL::X509::ExtensionFactory.new
+    ef.subject_certificate = root_cert
+    ef.issuer_certificate = root_cert
+    root_cert.add_extension(ef.create_extension("basicConstraints","CA:TRUE",true))
+    root_cert.add_extension(ef.create_extension("keyUsage","keyCertSign, cRLSign", true))
+    root_cert.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
+    root_cert.add_extension(ef.create_extension("authorityKeyIdentifier","keyid:always",false))
+    root_cert.sign(root_key, OpenSSL::Digest.new('SHA256'))
+
+
+    key = OpenSSL::PKey::RSA.new 2048
+    cert = OpenSSL::X509::Certificate.new
+    cert.version = 2
+    cert.serial = 2
+    cert.subject = OpenSSL::X509::Name.parse "/DC=org/DC=truffleruby/CN=TruffleRuby certificate"
+    cert.issuer = root_cert.subject
+    cert.public_key = key.public_key
+    cert.not_before = Time.now
+    cert.not_after = cert.not_before + 1 * 365 * 24 * 60 * 60
+    ef = OpenSSL::X509::ExtensionFactory.new
+    ef.subject_certificate = cert
+    ef.issuer_certificate = root_cert
+    cert.add_extension(ef.create_extension("keyUsage","digitalSignature", true))
+    cert.add_extension(ef.create_extension("subjectKeyIdentifier","hash",false))
+    cert.sign(root_key, OpenSSL::Digest.new('SHA256'))
+
+    store = OpenSSL::X509::Store.new
+    store.add_cert(root_cert)
+    store.add_cert(cert)
+    store.verify(cert).should == false
+  end
+end
diff --git a/spec/ruby/library/openstruct/delete_field_spec.rb b/spec/ruby/library/openstruct/delete_field_spec.rb
index 9ac80196cc..12fed6c90d 100644
--- a/spec/ruby/library/openstruct/delete_field_spec.rb
+++ b/spec/ruby/library/openstruct/delete_field_spec.rb
@@ -8,12 +8,12 @@ describe "OpenStruct#delete_field" do
 
   it "removes the named field from self's method/value table" do
     @os.delete_field(:name)
-    @os[:name].should be_nil
+    @os[:name].should == nil
   end
 
   it "does remove the accessor methods" do
     @os.delete_field(:name)
-    @os.respond_to?(:name).should be_false
-    @os.respond_to?(:name=).should be_false
+    @os.respond_to?(:name).should == false
+    @os.respond_to?(:name=).should == false
   end
 end
diff --git a/spec/ruby/library/openstruct/equal_value_spec.rb b/spec/ruby/library/openstruct/equal_value_spec.rb
index 103ac13588..c72c09ce14 100644
--- a/spec/ruby/library/openstruct/equal_value_spec.rb
+++ b/spec/ruby/library/openstruct/equal_value_spec.rb
@@ -8,21 +8,21 @@ describe "OpenStruct#==" do
   end
 
   it "returns false when the passed argument is no OpenStruct" do
-    (@os == Object.new).should be_false
-    (@os == "Test").should be_false
-    (@os == 10).should be_false
-    (@os == :sym).should be_false
+    (@os == Object.new).should == false
+    (@os == "Test").should == false
+    (@os == 10).should == false
+    (@os == :sym).should == false
   end
 
   it "returns true when self and other are equal method/value wise" do
-    (@os == @os).should be_true
-    (@os == OpenStruct.new(name: "John")).should be_true
-    (@os == OpenStructSpecs::OpenStructSub.new(name: "John")).should be_true
+    (@os == @os).should == true
+    (@os == OpenStruct.new(name: "John")).should == true
+    (@os == OpenStructSpecs::OpenStructSub.new(name: "John")).should == true
 
-    (@os == OpenStruct.new(name: "Jonny")).should be_false
-    (@os == OpenStructSpecs::OpenStructSub.new(name: "Jonny")).should be_false
+    (@os == OpenStruct.new(name: "Jonny")).should == false
+    (@os == OpenStructSpecs::OpenStructSub.new(name: "Jonny")).should == false
 
-    (@os == OpenStruct.new(name: "John", age: 20)).should be_false
-    (@os == OpenStructSpecs::OpenStructSub.new(name: "John", age: 20)).should be_false
+    (@os == OpenStruct.new(name: "John", age: 20)).should == false
+    (@os == OpenStructSpecs::OpenStructSub.new(name: "John", age: 20)).should == false
   end
 end
diff --git a/spec/ruby/library/openstruct/frozen_spec.rb b/spec/ruby/library/openstruct/frozen_spec.rb
index 63767bb54d..c37fd18c8c 100644
--- a/spec/ruby/library/openstruct/frozen_spec.rb
+++ b/spec/ruby/library/openstruct/frozen_spec.rb
@@ -9,28 +9,30 @@ describe "OpenStruct.new when frozen" do
   # method_missing case handled in method_missing_spec.rb
   #
   it "is still readable" do
-    @os.age.should eql(70)
-    @os.pension.should eql(300)
+    @os.age.should.eql?(70)
+    @os.pension.should.eql?(300)
     @os.name.should == "John Smith"
   end
 
   it "is not writable" do
-    ->{ @os.age = 42 }.should raise_error( RuntimeError )
+    ->{ @os.age = 42 }.should.raise( RuntimeError )
   end
 
   it "cannot create new fields" do
-    ->{ @os.state = :new }.should raise_error( RuntimeError )
+    ->{ @os.state = :new }.should.raise( RuntimeError )
   end
 
   it "creates a frozen clone" do
     f = @os.clone
+    f.frozen?.should == true
     f.age.should == 70
-    ->{ f.age = 0 }.should raise_error( RuntimeError )
-    ->{ f.state = :newer }.should raise_error( RuntimeError )
+    ->{ f.age = 0 }.should.raise( RuntimeError )
+    ->{ f.state = :newer }.should.raise( RuntimeError )
   end
 
   it "creates an unfrozen dup" do
     d = @os.dup
+    d.frozen?.should == false
     d.age.should == 70
     d.age = 42
     d.age.should == 42
diff --git a/spec/ruby/library/openstruct/initialize_spec.rb b/spec/ruby/library/openstruct/initialize_spec.rb
index dee5de48c6..52304cf780 100644
--- a/spec/ruby/library/openstruct/initialize_spec.rb
+++ b/spec/ruby/library/openstruct/initialize_spec.rb
@@ -3,6 +3,6 @@ require 'ostruct'
 
 describe "OpenStruct#initialize" do
   it "is private" do
-    OpenStruct.should have_private_instance_method(:initialize)
+    OpenStruct.private_instance_methods(false).should.include?(:initialize)
   end
 end
diff --git a/spec/ruby/library/openstruct/marshal_load_spec.rb b/spec/ruby/library/openstruct/marshal_load_spec.rb
index e07c4cef05..a8cdda3b43 100644
--- a/spec/ruby/library/openstruct/marshal_load_spec.rb
+++ b/spec/ruby/library/openstruct/marshal_load_spec.rb
@@ -4,9 +4,9 @@ require "ostruct"
 describe "OpenStruct#marshal_load when passed [Hash]" do
   it "defines methods based on the passed Hash" do
     os = OpenStruct.new
-    os.marshal_load(age: 20, name: "John")
+    os.send :marshal_load, age: 20, name: "John"
 
-    os.age.should eql(20)
+    os.age.should.eql?(20)
     os.name.should == "John"
   end
 end
diff --git a/spec/ruby/library/openstruct/method_missing_spec.rb b/spec/ruby/library/openstruct/method_missing_spec.rb
index 1992b7255c..cf6734d629 100644
--- a/spec/ruby/library/openstruct/method_missing_spec.rb
+++ b/spec/ruby/library/openstruct/method_missing_spec.rb
@@ -7,43 +7,18 @@ describe "OpenStruct#method_missing when called with a method name ending in '='
   end
 
   it "raises an ArgumentError when not passed any additional arguments" do
-    -> { @os.method_missing(:test=) }.should raise_error(ArgumentError)
-  end
-
-  it "raises a TypeError when self is frozen" do
-    @os.freeze
-    -> { @os.method_missing(:test=, "test") }.should raise_error(RuntimeError)
-  end
-
-  it "creates accessor methods" do
-    @os.method_missing(:test=, "test")
-    @os.respond_to?(:test=).should be_true
-    @os.respond_to?(:test).should be_true
-
-    @os.test.should == "test"
-    @os.test = "changed"
-    @os.test.should == "changed"
+    -> { @os.send(:test=) }.should.raise(ArgumentError)
   end
 end
 
 describe "OpenStruct#method_missing when passed additional arguments" do
   it "raises a NoMethodError when the key does not exist" do
     os = OpenStruct.new
-    -> { os.method_missing(:test, 1, 2, 3) }.should raise_error(NoMethodError)
-  end
-
-  ruby_version_is "2.7" do
-    it "raises an ArgumentError when the key exists" do
-      os = OpenStruct.new(test: 20)
-      -> { os.method_missing(:test, 1, 2, 3) }.should raise_error(ArgumentError)
-    end
+    -> { os.test(1, 2, 3) }.should.raise(NoMethodError)
   end
-end
 
-describe "OpenStruct#method_missing when not passed any additional arguments" do
-  it "returns the value for the passed method from the method/value table" do
-    os = OpenStruct.new(age: 20)
-    os.method_missing(:age).should eql(20)
-    os.method_missing(:name).should be_nil
+  it "raises an ArgumentError when the key exists" do
+    os = OpenStruct.new(test: 20)
+    -> { os.test(1, 2, 3) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/openstruct/new_spec.rb b/spec/ruby/library/openstruct/new_spec.rb
index 5d2cacea40..9e53948c82 100644
--- a/spec/ruby/library/openstruct/new_spec.rb
+++ b/spec/ruby/library/openstruct/new_spec.rb
@@ -7,8 +7,8 @@ describe "OpenStruct.new when passed [Hash]" do
   end
 
   it "creates an attribute for each key of the passed Hash" do
-    @os.age.should eql(70)
-    @os.pension.should eql(300)
+    @os.age.should.eql?(70)
+    @os.pension.should.eql?(300)
     @os.name.should == "John Smith"
   end
 end
diff --git a/spec/ruby/library/openstruct/shared/inspect.rb b/spec/ruby/library/openstruct/shared/inspect.rb
index ffcd690e1f..d5fffa0e2e 100644
--- a/spec/ruby/library/openstruct/shared/inspect.rb
+++ b/spec/ruby/library/openstruct/shared/inspect.rb
@@ -4,7 +4,7 @@ describe :ostruct_inspect, shared: true do
     os.send(@method).should == "#<OpenStruct name=\"John Smith\">"
 
     os = OpenStruct.new(age: 20, name: "John Smith")
-    os.send(@method).should be_kind_of(String)
+    os.send(@method).should.is_a?(String)
   end
 
   it "correctly handles self-referential OpenStructs" do
diff --git a/spec/ruby/library/openstruct/to_h_spec.rb b/spec/ruby/library/openstruct/to_h_spec.rb
index ebdec16174..7d9c7db5dc 100644
--- a/spec/ruby/library/openstruct/to_h_spec.rb
+++ b/spec/ruby/library/openstruct/to_h_spec.rb
@@ -19,7 +19,7 @@ describe "OpenStruct#to_h" do
   end
 
   it "does not return the hash used as initializer" do
-    @to_h.should_not equal(@h)
+    @to_h.should_not.equal?(@h)
   end
 
   it "returns a Hash that is independent from the struct" do
@@ -27,44 +27,42 @@ describe "OpenStruct#to_h" do
     @os.age.should == 70
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        h = @os.to_h { |k, v| [k.to_s, v*2] }
-        h.should == { "name" => "John SmithJohn Smith", "age" => 140, "pension" => 600 }
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      h = @os.to_h { |k, v| [k.to_s, v*2] }
+      h.should == { "name" => "John SmithJohn Smith", "age" => 140, "pension" => 600 }
+    end
 
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          @os.to_h { |k, v| [k.to_s, v*2, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        @os.to_h { |k, v| [k.to_s, v*2, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
 
-        -> do
-          @os.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
+      -> do
+        @os.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
 
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          @os.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        @os.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
 
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
 
-        @os.to_h { |k| x }.should == { :b => 'b' }
-      end
+      @os.to_h { |k| x }.should == { :b => 'b' }
+    end
 
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
 
-        -> do
-          @os.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+      -> do
+        @os.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/library/pathname/absolute_spec.rb b/spec/ruby/library/pathname/absolute_spec.rb
index dce3ae72ee..109abb8ee9 100644
--- a/spec/ruby/library/pathname/absolute_spec.rb
+++ b/spec/ruby/library/pathname/absolute_spec.rb
@@ -4,19 +4,19 @@ require 'pathname'
 describe "Pathname#absolute?" do
 
   it "returns true for the root directory" do
-    Pathname.new('/').absolute?.should == true
+    Pathname.new('/').should.absolute?
   end
 
   it "returns true for a dir starting with a slash" do
-    Pathname.new('/usr/local/bin').absolute?.should == true
+    Pathname.new('/usr/local/bin').should.absolute?
   end
 
   it "returns false for a dir not starting with a slash" do
-    Pathname.new('fish').absolute?.should == false
+    Pathname.new('fish').should_not.absolute?
   end
 
   it "returns false for a dir not starting with a slash" do
-    Pathname.new('fish/dog/cow').absolute?.should == false
+    Pathname.new('fish/dog/cow').should_not.absolute?
   end
 
 end
diff --git a/spec/ruby/library/pathname/birthtime_spec.rb b/spec/ruby/library/pathname/birthtime_spec.rb
new file mode 100644
index 0000000000..387f0aa54d
--- /dev/null
+++ b/spec/ruby/library/pathname/birthtime_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../spec_helper'
+require 'pathname'
+
+describe "Pathname#birthtime" do
+  platform_is :windows, :darwin, :freebsd, :netbsd do
+    it "returns the birth time for self" do
+      Pathname.new(__FILE__).birthtime.should.is_a?(Time)
+    end
+  end
+
+  platform_is :openbsd do
+    it "raises an NotImplementedError" do
+      -> { Pathname.new(__FILE__).birthtime }.should.raise(NotImplementedError)
+    end
+  end
+end
diff --git a/spec/ruby/library/pathname/divide_spec.rb b/spec/ruby/library/pathname/divide_spec.rb
new file mode 100644
index 0000000000..8af79d0c8f
--- /dev/null
+++ b/spec/ruby/library/pathname/divide_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/plus'
+
+describe "Pathname#/" do
+  it_behaves_like :pathname_plus, :/
+end
diff --git a/spec/ruby/library/pathname/empty_spec.rb b/spec/ruby/library/pathname/empty_spec.rb
index 4deade5b64..9f0305a0f0 100644
--- a/spec/ruby/library/pathname/empty_spec.rb
+++ b/spec/ruby/library/pathname/empty_spec.rb
@@ -15,18 +15,18 @@ describe 'Pathname#empty?' do
   end
 
   it 'returns true when file is not empty' do
-    Pathname.new(__FILE__).empty?.should be_false
+    Pathname.new(__FILE__).empty?.should == false
   end
 
   it 'returns false when the directory is not empty' do
-    Pathname.new(__dir__).empty?.should be_false
+    Pathname.new(__dir__).empty?.should == false
   end
 
   it 'return true when file is empty' do
-    Pathname.new(@file).empty?.should be_true
+    Pathname.new(@file).empty?.should == true
   end
 
   it 'returns true when directory is empty' do
-    Pathname.new(@dir).empty?.should be_true
+    Pathname.new(@dir).empty?.should == true
   end
 end
diff --git a/spec/ruby/library/pathname/glob_spec.rb b/spec/ruby/library/pathname/glob_spec.rb
new file mode 100644
index 0000000000..e20e6f8f85
--- /dev/null
+++ b/spec/ruby/library/pathname/glob_spec.rb
@@ -0,0 +1,92 @@
+require_relative '../../spec_helper'
+require 'pathname'
+
+describe 'Pathname.glob' do
+  before :all  do
+    @dir = tmp('pathname_glob') + '/'
+    @file_1 = @dir + 'lib/ipaddr.rb'
+    @file_2 = @dir + 'lib/irb.rb'
+    @file_3 = @dir + 'lib/.hidden.rb'
+
+    touch @file_1
+    touch @file_2
+    touch @file_3
+  end
+
+  after :all do
+    rm_r @dir[0...-1]
+  end
+
+  it 'returns [] for no match' do
+    Pathname.glob(@dir + 'lib/*.js').should == []
+  end
+
+  it 'returns [] when the pathname does not exist' do
+    Pathname.glob('i_dont_exist/lib/*.js').should == []
+  end
+
+  it 'returns matching file paths' do
+    Pathname.glob(@dir + 'lib/*i*.rb').sort.should == [Pathname.new(@file_1), Pathname.new(@file_2)].sort
+  end
+
+  it 'returns matching file paths when a flag is provided' do
+    expected = [Pathname.new(@file_1), Pathname.new(@file_2), Pathname.new(@file_3)].sort
+    Pathname.glob(@dir + 'lib/*i*.rb', File::FNM_DOTMATCH).sort.should == expected
+  end
+
+  it 'returns matching file paths when supplied :base keyword argument' do
+    Pathname.glob('*i*.rb', base: @dir + 'lib').sort.should == [Pathname.new('ipaddr.rb'), Pathname.new('irb.rb')].sort
+  end
+
+  it "raises an ArgumentError when supplied a keyword argument other than :base" do
+    -> {
+      Pathname.glob('*i*.rb', foo: @dir + 'lib')
+    }.should.raise(ArgumentError, "unknown keyword: :foo")
+  end
+
+  it "does not raise an ArgumentError when supplied a flag and :base keyword argument" do
+    expected = [Pathname.new('ipaddr.rb'), Pathname.new('irb.rb'), Pathname.new('.hidden.rb')].sort
+    Pathname.glob('*i*.rb', File::FNM_DOTMATCH, base: @dir + 'lib').sort.should == expected
+  end
+end
+
+
+describe 'Pathname#glob' do
+  before :all  do
+    @dir = tmp('pathname_glob') + '/'
+    @file_1 = @dir + 'lib/ipaddr.rb'
+    @file_2 = @dir + 'lib/irb.rb'
+    @file_3 = @dir + 'lib/.hidden.rb'
+
+    touch @file_1
+    touch @file_2
+    touch @file_3
+  end
+
+  after :all do
+    rm_r @dir[0...-1]
+  end
+
+  it 'returns [] for no match' do
+    Pathname.new(@dir).glob('lib/*.js').should == []
+  end
+
+  it 'returns [] when the pathname does not exist' do
+    Pathname.new('./i_dont_exist').glob('lib/*.js').should == []
+  end
+
+  it 'returns matching file paths' do
+    Pathname.new(@dir).glob('lib/*i*.rb').sort.should == [Pathname.new(@file_1), Pathname.new(@file_2)].sort
+  end
+
+  it 'yields matching file paths to block' do
+    ary = []
+    Pathname.new(@dir).glob('lib/*i*.rb') { |p| ary << p }.should == nil
+    ary.sort.should == [Pathname.new(@file_1), Pathname.new(@file_2)].sort
+  end
+
+  it 'returns matching file paths when a flag is provided' do
+    expected = [Pathname.new(@file_1), Pathname.new(@file_2), Pathname.new(@file_3)].sort
+    Pathname.new(@dir).glob('lib/*i*.rb', File::FNM_DOTMATCH).sort.should == expected
+  end
+end
diff --git a/spec/ruby/library/pathname/inspect_spec.rb b/spec/ruby/library/pathname/inspect_spec.rb
new file mode 100644
index 0000000000..3abba6cbb5
--- /dev/null
+++ b/spec/ruby/library/pathname/inspect_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../spec_helper'
+require 'pathname'
+
+describe "Pathname#inspect" do
+  it "returns a consistent String" do
+    result = Pathname.new('/tmp').inspect
+    result.should.instance_of?(String)
+    result.should == "#<Pathname:/tmp>"
+  end
+end
diff --git a/spec/ruby/library/pathname/new_spec.rb b/spec/ruby/library/pathname/new_spec.rb
index f400444887..3ef9d9b76d 100644
--- a/spec/ruby/library/pathname/new_spec.rb
+++ b/spec/ruby/library/pathname/new_spec.rb
@@ -3,23 +3,18 @@ require 'pathname'
 
 describe "Pathname.new" do
   it "returns a new Pathname Object with 1 argument" do
-    Pathname.new('').should be_kind_of(Pathname)
+    Pathname.new('').should.is_a?(Pathname)
   end
 
   it "raises an ArgumentError when called with \0" do
-    -> { Pathname.new("\0")}.should raise_error(ArgumentError)
-  end
-
-  it "is tainted if path is tainted" do
-    path = '/usr/local/bin'.taint
-    Pathname.new(path).tainted?.should == true
+    -> { Pathname.new("\0")}.should.raise(ArgumentError)
   end
 
   it "raises a TypeError if not passed a String type" do
-    -> { Pathname.new(nil)   }.should raise_error(TypeError)
-    -> { Pathname.new(0)     }.should raise_error(TypeError)
-    -> { Pathname.new(true)  }.should raise_error(TypeError)
-    -> { Pathname.new(false) }.should raise_error(TypeError)
+    -> { Pathname.new(nil)   }.should.raise(TypeError)
+    -> { Pathname.new(0)     }.should.raise(TypeError)
+    -> { Pathname.new(true)  }.should.raise(TypeError)
+    -> { Pathname.new(false) }.should.raise(TypeError)
   end
 
   it "initializes with an object with to_path" do
diff --git a/spec/ruby/library/pathname/pathname_spec.rb b/spec/ruby/library/pathname/pathname_spec.rb
new file mode 100644
index 0000000000..6fa6fd2bcb
--- /dev/null
+++ b/spec/ruby/library/pathname/pathname_spec.rb
@@ -0,0 +1,19 @@
+require_relative '../../spec_helper'
+require 'pathname'
+
+describe "Kernel#Pathname" do
+  it "is a private instance method" do
+    Kernel.private_instance_methods(false).should.include?(:Pathname)
+  end
+
+  it "is also a public method" do
+    Kernel.should.respond_to?(:Pathname)
+  end
+
+  it "returns same argument when called with a pathname argument" do
+    path = Pathname('foo')
+    new_path = Pathname(path)
+
+    path.should.equal?(new_path)
+  end
+end
diff --git a/spec/ruby/library/pathname/plus_spec.rb b/spec/ruby/library/pathname/plus_spec.rb
new file mode 100644
index 0000000000..57e472c266
--- /dev/null
+++ b/spec/ruby/library/pathname/plus_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative 'shared/plus'
+
+describe "Pathname#+" do
+  it_behaves_like :pathname_plus, :+
+end
diff --git a/spec/ruby/library/pathname/realdirpath_spec.rb b/spec/ruby/library/pathname/realdirpath_spec.rb
index a9e44e354e..e50741a737 100644
--- a/spec/ruby/library/pathname/realdirpath_spec.rb
+++ b/spec/ruby/library/pathname/realdirpath_spec.rb
@@ -4,7 +4,7 @@ require 'pathname'
 describe "Pathname#realdirpath" do
 
   it "returns a Pathname" do
-    Pathname.pwd.realdirpath.should be_an_instance_of(Pathname)
+    Pathname.pwd.realdirpath.should.instance_of?(Pathname)
   end
 
 end
diff --git a/spec/ruby/library/pathname/realpath_spec.rb b/spec/ruby/library/pathname/realpath_spec.rb
index f2c654308e..d8b87f57d0 100644
--- a/spec/ruby/library/pathname/realpath_spec.rb
+++ b/spec/ruby/library/pathname/realpath_spec.rb
@@ -4,7 +4,7 @@ require 'pathname'
 describe "Pathname#realpath" do
 
   it "returns a Pathname" do
-    Pathname.pwd.realpath.should be_an_instance_of(Pathname)
+    Pathname.pwd.realpath.should.instance_of?(Pathname)
   end
 
 end
diff --git a/spec/ruby/library/pathname/relative_path_from_spec.rb b/spec/ruby/library/pathname/relative_path_from_spec.rb
index abe9c80a45..7cbd22c3d6 100644
--- a/spec/ruby/library/pathname/relative_path_from_spec.rb
+++ b/spec/ruby/library/pathname/relative_path_from_spec.rb
@@ -7,11 +7,11 @@ describe "Pathname#relative_path_from" do
   end
 
   it "raises an error when the two paths do not share a common prefix" do
-    -> { relative_path_str('/usr', 'foo') }.should raise_error(ArgumentError)
+    -> { relative_path_str('/usr', 'foo') }.should.raise(ArgumentError)
   end
 
   it "raises an error when the base directory has .." do
-    -> { relative_path_str('a', '..') }.should raise_error(ArgumentError)
+    -> { relative_path_str('a', '..') }.should.raise(ArgumentError)
   end
 
   it "returns a path relative from root" do
@@ -48,4 +48,8 @@ describe "Pathname#relative_path_from" do
     relative_path_str('..', '..').should == '.'
     relative_path_str('..', '.').should == '..'
   end
+
+  it 'converts string argument to Pathname' do
+    Pathname.new('/usr/bin/ls').relative_path_from('/usr').to_s.should == 'bin/ls'
+  end
 end
diff --git a/spec/ruby/library/pathname/relative_spec.rb b/spec/ruby/library/pathname/relative_spec.rb
index 1a08891e6c..0fab9a7b9f 100644
--- a/spec/ruby/library/pathname/relative_spec.rb
+++ b/spec/ruby/library/pathname/relative_spec.rb
@@ -4,19 +4,19 @@ require 'pathname'
 describe "Pathname#relative?" do
 
   it "returns false for the root directory" do
-    Pathname.new('/').relative?.should == false
+    Pathname.new('/').should_not.relative?
   end
 
   it "returns false for a dir starting with a slash" do
-    Pathname.new('/usr/local/bin').relative?.should == false
+    Pathname.new('/usr/local/bin').should_not.relative?
   end
 
   it "returns true for a dir not starting with a slash" do
-    Pathname.new('fish').relative?.should == true
+    Pathname.new('fish').should.relative?
   end
 
   it "returns true for a dir not starting with a slash" do
-    Pathname.new('fish/dog/cow').relative?.should == true
+    Pathname.new('fish/dog/cow').should.relative?
   end
 
 end
diff --git a/spec/ruby/library/pathname/root_spec.rb b/spec/ruby/library/pathname/root_spec.rb
index 5fec0ee956..cd2be24516 100644
--- a/spec/ruby/library/pathname/root_spec.rb
+++ b/spec/ruby/library/pathname/root_spec.rb
@@ -4,23 +4,23 @@ require 'pathname'
 describe "Pathname#root?" do
 
   it "returns true for root directories" do
-    Pathname.new('/').root?.should == true
+    Pathname.new('/').should.root?
   end
 
   it "returns false for empty string" do
-    Pathname.new('').root?.should == false
+    Pathname.new('').should_not.root?
   end
 
   it "returns false for a top level directory" do
-    Pathname.new('/usr').root?.should == false
+    Pathname.new('/usr').should_not.root?
   end
 
   it "returns false for a top level with .. appended directory" do
-    Pathname.new('/usr/..').root?.should == false
+    Pathname.new('/usr/..').should_not.root?
   end
 
   it "returns false for a directory below top level" do
-    Pathname.new('/usr/local/bin/').root?.should == false
+    Pathname.new('/usr/local/bin/').should_not.root?
   end
 
 end
diff --git a/spec/ruby/library/pathname/shared/plus.rb b/spec/ruby/library/pathname/shared/plus.rb
new file mode 100644
index 0000000000..b3b896ea43
--- /dev/null
+++ b/spec/ruby/library/pathname/shared/plus.rb
@@ -0,0 +1,8 @@
+require 'pathname'
+
+describe :pathname_plus, shared: true do
+  it "appends a pathname to self" do
+    p = Pathname.new("/usr")
+    p.send(@method, "bin/ruby").should == Pathname.new("/usr/bin/ruby")
+  end
+end
diff --git a/spec/ruby/library/pp/pp_spec.rb b/spec/ruby/library/pp/pp_spec.rb
index 06b22601d8..e45a6bb94f 100644
--- a/spec/ruby/library/pp/pp_spec.rb
+++ b/spec/ruby/library/pp/pp_spec.rb
@@ -20,4 +20,11 @@ describe "PP.pp" do
 
     other_out.to_s.should == "[1, 2, 3]\n"
   end
+
+  it 'correctly prints a Hash' do
+    hash = { 'key' => 42 }
+    -> {
+      PP.pp hash
+    }.should output("#{hash.inspect}\n")
+  end
 end
diff --git a/spec/ruby/library/prime/each_spec.rb b/spec/ruby/library/prime/each_spec.rb
index b99cf7cf0e..d81e952a88 100644
--- a/spec/ruby/library/prime/each_spec.rb
+++ b/spec/ruby/library/prime/each_spec.rb
@@ -32,11 +32,11 @@ describe :prime_each, shared: true do
       all_prime &&= (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
     end
 
-    all_prime.should be_true
+    all_prime.should == true
   end
 
   it "returns the last evaluated expression in the passed block" do
-    @object.each { break :value }.should equal(:value)
+    @object.each { break :value }.should.equal?(:value)
   end
 
   describe "when not passed a block" do
@@ -45,23 +45,23 @@ describe :prime_each, shared: true do
     end
 
     it "returns an object that is Enumerable" do
-      @prime_enum.each.should be_kind_of(Enumerable)
+      @prime_enum.each.should.is_a?(Enumerable)
     end
 
     it "returns an object that responds to #with_index" do
-      @prime_enum.should respond_to(:with_index)
+      @prime_enum.should.respond_to?(:with_index)
     end
 
     it "returns an object that responds to #with_object" do
-      @prime_enum.should respond_to(:with_object)
+      @prime_enum.should.respond_to?(:with_object)
     end
 
     it "returns an object that responds to #next" do
-      @prime_enum.should respond_to(:next)
+      @prime_enum.should.respond_to?(:next)
     end
 
     it "returns an object that responds to #rewind" do
-      @prime_enum.should respond_to(:rewind)
+      @prime_enum.should.respond_to?(:rewind)
     end
 
     it "yields primes starting at 2 independent of prior enumerators" do
@@ -106,13 +106,13 @@ describe :prime_each_with_arguments, shared: true do
 
     ScratchPad.recorded.all? do |prime|
       (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
-    end.should be_true
+    end.should == true
 
-    ScratchPad.recorded.all? { |prime| prime <= bound }.should be_true
+    ScratchPad.recorded.all? { |prime| prime <= bound }.should == true
   end
 
   it "returns nil when no prime is generated" do
-    @object.each(1) { :value }.should be_nil
+    @object.each(1) { :value }.should == nil
   end
 
   it "yields primes starting at 2 independent of prior enumeration" do
@@ -132,7 +132,7 @@ describe :prime_each_with_arguments, shared: true do
   describe "when not passed a block" do
     it "returns an object that returns primes less than or equal to the bound" do
       bound = 100
-      @object.each(bound).all? { |prime| prime <= bound }.should be_true
+      @object.each(bound).all? { |prime| prime <= bound }.should == true
     end
   end
 end
diff --git a/spec/ruby/library/prime/instance_spec.rb b/spec/ruby/library/prime/instance_spec.rb
index 5183f36901..680895eb64 100644
--- a/spec/ruby/library/prime/instance_spec.rb
+++ b/spec/ruby/library/prime/instance_spec.rb
@@ -3,12 +3,12 @@ require 'prime'
 
 describe "Prime.instance" do
   it "returns a object representing the set of prime numbers" do
-    Prime.instance.should be_kind_of(Prime)
+    Prime.instance.should.is_a?(Prime)
   end
 
   it "returns a object with no obsolete features" do
-    Prime.instance.should_not respond_to(:succ)
-    Prime.instance.should_not respond_to(:next)
+    Prime.instance.should_not.respond_to?(:succ)
+    Prime.instance.should_not.respond_to?(:next)
   end
 
   it "does not complain anything" do
@@ -16,6 +16,6 @@ describe "Prime.instance" do
   end
 
   it "raises a ArgumentError when is called with some arguments" do
-    -> { Prime.instance(1) }.should raise_error(ArgumentError)
+    -> { Prime.instance(1) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/prime/integer/prime_division_spec.rb b/spec/ruby/library/prime/integer/prime_division_spec.rb
index be03438a6f..5631b22d0a 100644
--- a/spec/ruby/library/prime/integer/prime_division_spec.rb
+++ b/spec/ruby/library/prime/integer/prime_division_spec.rb
@@ -14,6 +14,6 @@ describe "Integer#prime_division" do
     -1.prime_division.should == [[-1, 1]]
   end
   it "raises ZeroDivisionError for 0" do
-    -> { 0.prime_division }.should raise_error(ZeroDivisionError)
+    -> { 0.prime_division }.should.raise(ZeroDivisionError)
   end
 end
diff --git a/spec/ruby/library/prime/integer/prime_spec.rb b/spec/ruby/library/prime/integer/prime_spec.rb
index 53de76d5ab..d24f883b19 100644
--- a/spec/ruby/library/prime/integer/prime_spec.rb
+++ b/spec/ruby/library/prime/integer/prime_spec.rb
@@ -3,15 +3,15 @@ require 'prime'
 
 describe "Integer#prime?" do
   it "returns a true value for prime numbers" do
-    2.prime?.should be_true
-    3.prime?.should be_true
-    (2**31-1).prime?.should be_true  # 8th Mersenne prime (M8)
+    2.prime?.should == true
+    3.prime?.should == true
+    (2**31-1).prime?.should == true  # 8th Mersenne prime (M8)
   end
 
   it "returns a false value for composite numbers" do
-    4.prime?.should be_false
-    15.prime?.should be_false
-    (2**32-1).prime?.should be_false
-    ( (2**17-1)*(2**19-1) ).prime?.should be_false  # M6*M7
+    4.prime?.should == false
+    15.prime?.should == false
+    (2**32-1).prime?.should == false
+    ( (2**17-1)*(2**19-1) ).prime?.should == false  # M6*M7
   end
 end
diff --git a/spec/ruby/library/prime/prime_division_spec.rb b/spec/ruby/library/prime/prime_division_spec.rb
index 6293478f59..cc39969a56 100644
--- a/spec/ruby/library/prime/prime_division_spec.rb
+++ b/spec/ruby/library/prime/prime_division_spec.rb
@@ -16,10 +16,10 @@ describe "Prime.prime_division" do
   end
 
   it "includes [[-1, 1]] in the divisors of a negative number" do
-    Prime.prime_division(-10).should include([-1, 1])
+    Prime.prime_division(-10).should.include?([-1, 1])
   end
 
   it "raises ZeroDivisionError for 0" do
-    -> { Prime.prime_division(0) }.should raise_error(ZeroDivisionError)
+    -> { Prime.prime_division(0) }.should.raise(ZeroDivisionError)
   end
 end
diff --git a/spec/ruby/library/prime/prime_spec.rb b/spec/ruby/library/prime/prime_spec.rb
index 0896c7f0f3..207c763aed 100644
--- a/spec/ruby/library/prime/prime_spec.rb
+++ b/spec/ruby/library/prime/prime_spec.rb
@@ -3,15 +3,15 @@ require 'prime'
 
 describe "Prime#prime?" do
   it "returns a true value for prime numbers" do
-    Prime.prime?(2).should be_true
-    Prime.prime?(3).should be_true
-    Prime.prime?(2**31-1).should be_true  # 8th Mersenne prime (M8)
+    Prime.prime?(2).should == true
+    Prime.prime?(3).should == true
+    Prime.prime?(2**31-1).should == true  # 8th Mersenne prime (M8)
   end
 
   it "returns a false value for composite numbers" do
-    Prime.prime?(4).should be_false
-    Prime.prime?(15).should be_false
-    Prime.prime?(2**32-1).should be_false
-    Prime.prime?( (2**17-1)*(2**19-1) ).should be_false  # M6*M7
+    Prime.prime?(4).should == false
+    Prime.prime?(15).should == false
+    Prime.prime?(2**32-1).should == false
+    Prime.prime?( (2**17-1)*(2**19-1) ).should == false  # M6*M7
   end
 end
diff --git a/spec/ruby/library/random/formatter/alphanumeric_spec.rb b/spec/ruby/library/random/formatter/alphanumeric_spec.rb
new file mode 100644
index 0000000000..62a4698d0d
--- /dev/null
+++ b/spec/ruby/library/random/formatter/alphanumeric_spec.rb
@@ -0,0 +1,54 @@
+require_relative '../../../spec_helper'
+
+require 'random/formatter'
+
+describe "Random::Formatter#alphanumeric" do
+  before :each do
+    @object = Object.new
+    @object.extend(Random::Formatter)
+    @object.define_singleton_method(:bytes) do |n|
+      "\x00".b * n
+    end
+  end
+
+  it "generates a random alphanumeric string" do
+    @object.alphanumeric.should =~ /\A[A-Za-z0-9]+\z/
+  end
+
+  it "has a default size of 16 characters" do
+    @object.alphanumeric.size.should == 16
+  end
+
+  it "accepts a 'size' argument" do
+    @object.alphanumeric(10).size.should == 10
+  end
+
+  it "uses the default size if 'nil' is given as size argument" do
+    @object.alphanumeric(nil).size.should == 16
+  end
+
+  it "raises an ArgumentError if the size is not numeric" do
+    -> {
+      @object.alphanumeric("10")
+    }.should.raise(ArgumentError)
+  end
+
+  it "does not coerce the size argument with #to_int" do
+    size = mock("size")
+    size.should_not_receive(:to_int)
+    -> {
+      @object.alphanumeric(size)
+    }.should.raise(ArgumentError)
+  end
+
+  it "accepts a 'chars' argument with the output alphabet" do
+    @object.alphanumeric(chars: ['a', 'b']).should =~ /\A[ab]+\z/
+  end
+
+  it "converts the elements of chars using #to_s" do
+    to_s = mock("to_s")
+    to_s.should_receive(:to_s).and_return("[mock to_s]")
+    # Using 1 value in chars results in an infinite loop
+    @object.alphanumeric(1, chars: [to_s, to_s]).should == "[mock to_s]"
+  end
+end
diff --git a/spec/ruby/library/rbconfig/rbconfig_spec.rb b/spec/ruby/library/rbconfig/rbconfig_spec.rb
index 7c3fbf6c58..4195128a05 100644
--- a/spec/ruby/library/rbconfig/rbconfig_spec.rb
+++ b/spec/ruby/library/rbconfig/rbconfig_spec.rb
@@ -4,11 +4,18 @@ require 'rbconfig'
 describe 'RbConfig::CONFIG' do
   it 'values are all strings' do
     RbConfig::CONFIG.each do |k, v|
-      k.should be_kind_of String
-      v.should be_kind_of String
+      k.should.is_a? String
+      v.should.is_a? String
     end
   end
 
+  it 'has MAJOR, MINOR, TEENY, and PATCHLEVEL matching RUBY_VERSION and RUBY_PATCHLEVEL' do
+    major, minor, teeny = RUBY_VERSION.split('.')
+    RbConfig::CONFIG.values_at("MAJOR", "MINOR", "TEENY", "PATCHLEVEL").should == [
+      major, minor, teeny, RUBY_PATCHLEVEL.to_s
+    ]
+  end
+
   # These directories have no meanings before the installation.
   guard -> { RbConfig::TOPDIR } do
     it "['rubylibdir'] returns the directory containing Ruby standard libraries" do
@@ -22,6 +29,95 @@ describe 'RbConfig::CONFIG' do
       File.directory?(archdir).should == true
       File.should.exist?("#{archdir}/etc.#{RbConfig::CONFIG['DLEXT']}")
     end
+
+    it "['sitelibdir'] is set and is part of $LOAD_PATH" do
+      sitelibdir = RbConfig::CONFIG['sitelibdir']
+      sitelibdir.should.is_a? String
+      $LOAD_PATH.map{|path| File.realpath(path) rescue path }.should.include? sitelibdir
+    end
+  end
+
+  it "contains no frozen strings even with --enable-frozen-string-literal" do
+    ruby_exe(<<-RUBY, options: '--enable-frozen-string-literal').should == "Done\n"
+      require 'rbconfig'
+      RbConfig::CONFIG.each do |k, v|
+        if v.frozen?
+          puts "\#{k} Failure"
+        end
+      end
+      puts 'Done'
+    RUBY
+  end
+
+  platform_is_not :windows do
+    it "['LIBRUBY'] is the same as LIBRUBY_SO if and only if ENABLE_SHARED" do
+      case RbConfig::CONFIG['ENABLE_SHARED']
+      when 'yes'
+        RbConfig::CONFIG['LIBRUBY'].should == RbConfig::CONFIG['LIBRUBY_SO']
+      when 'no'
+        RbConfig::CONFIG['LIBRUBY'].should_not == RbConfig::CONFIG['LIBRUBY_SO']
+      end
+    end
+  end
+
+  guard -> { RbConfig::TOPDIR } do
+    it "libdir/LIBRUBY_SO is the path to libruby and it exists if and only if ENABLE_SHARED" do
+      libdirname = RbConfig::CONFIG['LIBPATHENV'] == 'PATH' ? 'bindir' :
+                     RbConfig::CONFIG['libdirname']
+      libdir = RbConfig::CONFIG[libdirname]
+      libruby_so = "#{libdir}/#{RbConfig::CONFIG['LIBRUBY_SO']}"
+      case RbConfig::CONFIG['ENABLE_SHARED']
+      when 'yes'
+        File.should.exist?(libruby_so)
+      when 'no'
+        File.should_not.exist?(libruby_so)
+      end
+    end
+  end
+
+  platform_is :linux do
+    it "['AR'] exists and can be executed" do
+      ar = RbConfig::CONFIG.fetch('AR')
+      out = `#{ar} --version`
+      $?.should.success?
+      out.should_not.empty?
+    end
+
+    it "['STRIP'] exists and can be executed" do
+      strip = RbConfig::CONFIG.fetch('STRIP')
+      copy = tmp("sh")
+      cp '/bin/sh', copy
+      begin
+        out = `#{strip} #{copy}`
+        $?.should.success?
+      ensure
+        rm_r copy
+      end
+    end
+  end
+
+  guard -> { %w[aarch64 arm64].include? RbConfig::CONFIG['host_cpu'] } do
+    it "['host_cpu'] returns CPU architecture properly for AArch64" do
+      platform_is :darwin do
+        RbConfig::CONFIG['host_cpu'].should == 'arm64'
+      end
+
+      platform_is_not :darwin do
+        RbConfig::CONFIG['host_cpu'].should == 'aarch64'
+      end
+    end
+  end
+
+  guard -> { platform_is(:linux) || platform_is(:darwin) } do
+    it "['host_os'] returns a proper OS name or platform" do
+      platform_is :darwin do
+        RbConfig::CONFIG['host_os'].should.match?(/darwin/)
+      end
+
+      platform_is :linux do
+        RbConfig::CONFIG['host_os'].should.match?(/linux/)
+      end
+    end
   end
 end
 
@@ -34,3 +130,34 @@ describe "RbConfig::TOPDIR" do
     end
   end
 end
+
+describe "RUBY_PLATFORM" do
+  it "RUBY_PLATFORM contains a proper CPU architecture" do
+    RUBY_PLATFORM.should.include? RbConfig::CONFIG['host_cpu']
+  end
+
+  guard -> { platform_is(:linux) || platform_is(:darwin) } do
+    it "RUBY_PLATFORM contains OS name" do
+      # don't use RbConfig::CONFIG['host_os'] as far as it could be slightly different, e.g. linux-gnu
+      platform_is(:linux) do
+        RUBY_PLATFORM.should.include? 'linux'
+      end
+
+      platform_is(:darwin) do
+        RUBY_PLATFORM.should.include? 'darwin'
+      end
+    end
+  end
+end
+
+describe "RUBY_DESCRIPTION" do
+  guard_not -> { RUBY_ENGINE == "ruby" && !RbConfig::TOPDIR } do
+    it "contains version" do
+      RUBY_DESCRIPTION.should.include? RUBY_VERSION
+    end
+
+    it "contains RUBY_PLATFORM" do
+      RUBY_DESCRIPTION.should.include? RUBY_PLATFORM
+    end
+  end
+end
diff --git a/spec/ruby/library/rbconfig/sizeof/limits_spec.rb b/spec/ruby/library/rbconfig/sizeof/limits_spec.rb
new file mode 100644
index 0000000000..08b1185965
--- /dev/null
+++ b/spec/ruby/library/rbconfig/sizeof/limits_spec.rb
@@ -0,0 +1,40 @@
+require_relative '../../../spec_helper'
+require 'rbconfig/sizeof'
+
+describe "RbConfig::LIMITS" do
+  it "is a Hash" do
+    RbConfig::LIMITS.should.is_a?(Hash)
+  end
+
+  it "has string keys and numeric values" do
+    RbConfig::LIMITS.each do |key, value|
+      key.should.is_a? String
+      value.should.is_a? Numeric
+    end
+  end
+
+  it "contains FIXNUM_MIN and FIXNUM_MAX" do
+    RbConfig::LIMITS["FIXNUM_MIN"].should < 0
+    RbConfig::LIMITS["FIXNUM_MAX"].should > 0
+  end
+
+  it "contains CHAR_MIN and CHAR_MAX" do
+    RbConfig::LIMITS["CHAR_MIN"].should <= 0
+    RbConfig::LIMITS["CHAR_MAX"].should > 0
+  end
+
+  it "contains SHRT_MIN and SHRT_MAX" do
+    RbConfig::LIMITS["SHRT_MIN"].should == -32768
+    RbConfig::LIMITS["SHRT_MAX"].should == 32767
+  end
+
+  it "contains INT_MIN and INT_MAX" do
+    RbConfig::LIMITS["INT_MIN"].should < 0
+    RbConfig::LIMITS["INT_MAX"].should > 0
+  end
+
+  it "contains LONG_MIN and LONG_MAX" do
+    RbConfig::LIMITS["LONG_MIN"].should < 0
+    RbConfig::LIMITS["LONG_MAX"].should > 0
+  end
+end
diff --git a/spec/ruby/library/rbconfig/sizeof/sizeof_spec.rb b/spec/ruby/library/rbconfig/sizeof/sizeof_spec.rb
index f2582dc4fd..b74dae5166 100644
--- a/spec/ruby/library/rbconfig/sizeof/sizeof_spec.rb
+++ b/spec/ruby/library/rbconfig/sizeof/sizeof_spec.rb
@@ -3,13 +3,13 @@ require 'rbconfig/sizeof'
 
 describe "RbConfig::SIZEOF" do
   it "is a Hash" do
-    RbConfig::SIZEOF.should be_kind_of(Hash)
+    RbConfig::SIZEOF.should.is_a?(Hash)
   end
 
   it "has string keys and integer values" do
     RbConfig::SIZEOF.each do |key, value|
-      key.should be_kind_of String
-      value.should be_kind_of Integer
+      key.should.is_a? String
+      value.should.is_a? Integer
     end
   end
 
diff --git a/spec/ruby/library/rbconfig/unicode_emoji_version_spec.rb b/spec/ruby/library/rbconfig/unicode_emoji_version_spec.rb
new file mode 100644
index 0000000000..521a750bf7
--- /dev/null
+++ b/spec/ruby/library/rbconfig/unicode_emoji_version_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+require 'rbconfig'
+
+describe "RbConfig::CONFIG['UNICODE_EMOJI_VERSION']" do
+  ruby_version_is ""..."3.4" do
+    it "is 15.0" do
+      RbConfig::CONFIG['UNICODE_EMOJI_VERSION'].should == "15.0"
+    end
+  end
+
+  # Caution: ruby_version_is means is_or_later
+  ruby_version_is "4.0" do
+    it "is 17.0" do
+      RbConfig::CONFIG['UNICODE_EMOJI_VERSION'].should == "17.0"
+    end
+  end
+end
diff --git a/spec/ruby/library/rbconfig/unicode_version_spec.rb b/spec/ruby/library/rbconfig/unicode_version_spec.rb
new file mode 100644
index 0000000000..5cdde74f79
--- /dev/null
+++ b/spec/ruby/library/rbconfig/unicode_version_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+require 'rbconfig'
+
+describe "RbConfig::CONFIG['UNICODE_VERSION']" do
+  ruby_version_is ""..."3.4" do
+    it "is 15.0.0" do
+      RbConfig::CONFIG['UNICODE_VERSION'].should == "15.0.0"
+    end
+  end
+
+  # Caution: ruby_version_is means is_or_later
+  ruby_version_is "4.0" do
+    it "is 17.0.0" do
+      RbConfig::CONFIG['UNICODE_VERSION'].should == "17.0.0"
+    end
+  end
+end
diff --git a/spec/ruby/library/readline/basic_quote_characters_spec.rb b/spec/ruby/library/readline/basic_quote_characters_spec.rb
index 216899d875..f6467c8be4 100644
--- a/spec/ruby/library/readline/basic_quote_characters_spec.rb
+++ b/spec/ruby/library/readline/basic_quote_characters_spec.rb
@@ -4,7 +4,7 @@ platform_is_not :darwin do
   with_feature :readline do
     describe "Readline.basic_quote_characters" do
       it "returns not nil" do
-        Readline.basic_quote_characters.should_not be_nil
+        Readline.basic_quote_characters.should_not == nil
       end
     end
 
diff --git a/spec/ruby/library/readline/basic_word_break_characters_spec.rb b/spec/ruby/library/readline/basic_word_break_characters_spec.rb
index daa0e1cb76..ef05d6560b 100644
--- a/spec/ruby/library/readline/basic_word_break_characters_spec.rb
+++ b/spec/ruby/library/readline/basic_word_break_characters_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.basic_word_break_characters" do
     it "returns not nil" do
-      Readline.basic_word_break_characters.should_not be_nil
+      Readline.basic_word_break_characters.should_not == nil
     end
   end
 
diff --git a/spec/ruby/library/readline/completer_quote_characters_spec.rb b/spec/ruby/library/readline/completer_quote_characters_spec.rb
index 86c58f3cf6..1109ea1f03 100644
--- a/spec/ruby/library/readline/completer_quote_characters_spec.rb
+++ b/spec/ruby/library/readline/completer_quote_characters_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.completer_quote_characters" do
     it "returns nil" do
-      Readline.completer_quote_characters.should be_nil
+      Readline.completer_quote_characters.should == nil
     end
   end
 
diff --git a/spec/ruby/library/readline/completer_word_break_characters_spec.rb b/spec/ruby/library/readline/completer_word_break_characters_spec.rb
index c72f1135c4..91a002b9de 100644
--- a/spec/ruby/library/readline/completer_word_break_characters_spec.rb
+++ b/spec/ruby/library/readline/completer_word_break_characters_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.completer_word_break_characters" do
     it "returns nil" do
-      Readline.completer_word_break_characters.should be_nil
+      Readline.completer_word_break_characters.should == nil
     end
   end
 
diff --git a/spec/ruby/library/readline/completion_append_character_spec.rb b/spec/ruby/library/readline/completion_append_character_spec.rb
index 615b523f4e..2a14d5d30e 100644
--- a/spec/ruby/library/readline/completion_append_character_spec.rb
+++ b/spec/ruby/library/readline/completion_append_character_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.completion_append_character" do
     it "returns not nil" do
-      Readline.completion_append_character.should_not be_nil
+      Readline.completion_append_character.should_not == nil
     end
   end
 
diff --git a/spec/ruby/library/readline/completion_case_fold_spec.rb b/spec/ruby/library/readline/completion_case_fold_spec.rb
index 966f5d6c79..b6a4aab101 100644
--- a/spec/ruby/library/readline/completion_case_fold_spec.rb
+++ b/spec/ruby/library/readline/completion_case_fold_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.completion_case_fold" do
     it "returns nil" do
-      Readline.completion_case_fold.should be_nil
+      Readline.completion_case_fold.should == nil
     end
   end
 
diff --git a/spec/ruby/library/readline/completion_proc_spec.rb b/spec/ruby/library/readline/completion_proc_spec.rb
index 2d7a353ec5..037fc6de21 100644
--- a/spec/ruby/library/readline/completion_proc_spec.rb
+++ b/spec/ruby/library/readline/completion_proc_spec.rb
@@ -3,7 +3,7 @@ require_relative 'spec_helper'
 with_feature :readline do
   describe "Readline.completion_proc" do
     it "returns nil" do
-      Readline.completion_proc.should be_nil
+      Readline.completion_proc.should == nil
     end
   end
 
@@ -16,7 +16,7 @@ with_feature :readline do
     end
 
     it "returns an ArgumentError if not given an Proc or #call" do
-      -> { Readline.completion_proc = "test" }.should raise_error(ArgumentError)
+      -> { Readline.completion_proc = "test" }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/constants_spec.rb b/spec/ruby/library/readline/constants_spec.rb
index 8fee274866..91536ce1cc 100644
--- a/spec/ruby/library/readline/constants_spec.rb
+++ b/spec/ruby/library/readline/constants_spec.rb
@@ -11,8 +11,8 @@ with_feature :readline do
   describe "Readline::VERSION" do
     it "is defined and is a non-empty String" do
       Readline.const_defined?(:VERSION).should == true
-      Readline::VERSION.should be_kind_of(String)
-      Readline::VERSION.should_not be_empty
+      Readline::VERSION.should.is_a?(String)
+      Readline::VERSION.should_not.empty?
     end
   end
 end
diff --git a/spec/ruby/library/readline/emacs_editing_mode_spec.rb b/spec/ruby/library/readline/emacs_editing_mode_spec.rb
index f7e8eda982..93ded3d023 100644
--- a/spec/ruby/library/readline/emacs_editing_mode_spec.rb
+++ b/spec/ruby/library/readline/emacs_editing_mode_spec.rb
@@ -4,7 +4,7 @@ platform_is_not :darwin do
   with_feature :readline do
     describe "Readline.emacs_editing_mode" do
       it "returns nil" do
-        Readline.emacs_editing_mode.should be_nil
+        Readline.emacs_editing_mode.should == nil
       end
     end
   end
diff --git a/spec/ruby/library/readline/filename_quote_characters_spec.rb b/spec/ruby/library/readline/filename_quote_characters_spec.rb
index de8ce700a8..6bcb04fc79 100644
--- a/spec/ruby/library/readline/filename_quote_characters_spec.rb
+++ b/spec/ruby/library/readline/filename_quote_characters_spec.rb
@@ -4,7 +4,7 @@ platform_is_not :darwin do
   with_feature :readline do
     describe "Readline.filename_quote_characters" do
       it "returns nil" do
-        Readline.filename_quote_characters.should be_nil
+        Readline.filename_quote_characters.should == nil
       end
     end
 
diff --git a/spec/ruby/library/readline/history/append_spec.rb b/spec/ruby/library/readline/history/append_spec.rb
index 5383271374..be0e515b84 100644
--- a/spec/ruby/library/readline/history/append_spec.rb
+++ b/spec/ruby/library/readline/history/append_spec.rb
@@ -22,7 +22,7 @@ with_feature :readline do
     end
 
     it "raises a TypeError when the passed Object can't be converted to a String" do
-      -> { Readline::HISTORY << mock("Object") }.should raise_error(TypeError)
+      -> { Readline::HISTORY << mock("Object") }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/delete_at_spec.rb b/spec/ruby/library/readline/history/delete_at_spec.rb
index 8dcce259bb..4383ff7e83 100644
--- a/spec/ruby/library/readline/history/delete_at_spec.rb
+++ b/spec/ruby/library/readline/history/delete_at_spec.rb
@@ -31,15 +31,8 @@ with_feature :readline do
     end
 
     it "raises an IndexError when the given index is greater than the history size" do
-      -> { Readline::HISTORY.delete_at(10) }.should raise_error(IndexError)
-      -> { Readline::HISTORY.delete_at(-10) }.should raise_error(IndexError)
-    end
-
-    it "taints the returned strings" do
-      Readline::HISTORY.push("1", "2", "3")
-      Readline::HISTORY.delete_at(0).tainted?.should be_true
-      Readline::HISTORY.delete_at(0).tainted?.should be_true
-      Readline::HISTORY.delete_at(0).tainted?.should be_true
+      -> { Readline::HISTORY.delete_at(10) }.should.raise(IndexError)
+      -> { Readline::HISTORY.delete_at(-10) }.should.raise(IndexError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/each_spec.rb b/spec/ruby/library/readline/history/each_spec.rb
index 4b87df7640..aa48dd46df 100644
--- a/spec/ruby/library/readline/history/each_spec.rb
+++ b/spec/ruby/library/readline/history/each_spec.rb
@@ -19,11 +19,5 @@ with_feature :readline do
       end
       result.should == ["1", "2", "3"]
     end
-
-    it "yields tainted Objects" do
-      Readline::HISTORY.each do |x|
-        x.tainted?.should be_true
-      end
-    end
   end
 end
diff --git a/spec/ruby/library/readline/history/element_reference_spec.rb b/spec/ruby/library/readline/history/element_reference_spec.rb
index 09cac5e28f..1f1642626f 100644
--- a/spec/ruby/library/readline/history/element_reference_spec.rb
+++ b/spec/ruby/library/readline/history/element_reference_spec.rb
@@ -12,11 +12,6 @@ with_feature :readline do
       Readline::HISTORY.pop
     end
 
-    it "returns tainted objects" do
-      Readline::HISTORY[0].tainted?.should be_true
-      Readline::HISTORY[1].tainted?.should be_true
-    end
-
     it "returns the history item at the passed index" do
       Readline::HISTORY[0].should == "1"
       Readline::HISTORY[1].should == "2"
@@ -28,13 +23,13 @@ with_feature :readline do
     end
 
     it "raises an IndexError when there is no item at the passed index" do
-      -> { Readline::HISTORY[-10] }.should raise_error(IndexError)
-      -> { Readline::HISTORY[-9] }.should raise_error(IndexError)
-      -> { Readline::HISTORY[-8] }.should raise_error(IndexError)
+      -> { Readline::HISTORY[-10] }.should.raise(IndexError)
+      -> { Readline::HISTORY[-9] }.should.raise(IndexError)
+      -> { Readline::HISTORY[-8] }.should.raise(IndexError)
 
-      -> { Readline::HISTORY[8] }.should raise_error(IndexError)
-      -> { Readline::HISTORY[9] }.should raise_error(IndexError)
-      -> { Readline::HISTORY[10] }.should raise_error(IndexError)
+      -> { Readline::HISTORY[8] }.should.raise(IndexError)
+      -> { Readline::HISTORY[9] }.should.raise(IndexError)
+      -> { Readline::HISTORY[10] }.should.raise(IndexError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/element_set_spec.rb b/spec/ruby/library/readline/history/element_set_spec.rb
index 776adaacd1..0787b6343d 100644
--- a/spec/ruby/library/readline/history/element_set_spec.rb
+++ b/spec/ruby/library/readline/history/element_set_spec.rb
@@ -17,7 +17,7 @@ with_feature :readline do
     end
 
     it "raises an IndexError when there is no item at the passed positive index" do
-      -> { Readline::HISTORY[10] = "test" }.should raise_error(IndexError)
+      -> { Readline::HISTORY[10] = "test" }.should.raise(IndexError)
     end
 
     it "sets the item at the given index" do
@@ -29,7 +29,7 @@ with_feature :readline do
     end
 
     it "raises an IndexError when there is no item at the passed negative index" do
-      -> { Readline::HISTORY[10] = "test" }.should raise_error(IndexError)
+      -> { Readline::HISTORY[10] = "test" }.should.raise(IndexError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/empty_spec.rb b/spec/ruby/library/readline/history/empty_spec.rb
index 31d01d9601..5b722dccd3 100644
--- a/spec/ruby/library/readline/history/empty_spec.rb
+++ b/spec/ruby/library/readline/history/empty_spec.rb
@@ -3,11 +3,11 @@ require_relative '../spec_helper'
 with_feature :readline do
   describe "Readline::HISTORY.empty?" do
     it "returns true when the history is empty" do
-      Readline::HISTORY.should be_empty
+      Readline::HISTORY.should.empty?
       Readline::HISTORY.push("test")
-      Readline::HISTORY.should_not be_empty
+      Readline::HISTORY.should_not.empty?
       Readline::HISTORY.pop
-      Readline::HISTORY.should be_empty
+      Readline::HISTORY.should.empty?
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/history_spec.rb b/spec/ruby/library/readline/history/history_spec.rb
index 927dd52ebf..3233071033 100644
--- a/spec/ruby/library/readline/history/history_spec.rb
+++ b/spec/ruby/library/readline/history/history_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 with_feature :readline do
   describe "Readline::HISTORY" do
     it "is extended with the Enumerable module" do
-      Readline::HISTORY.should be_kind_of(Enumerable)
+      Readline::HISTORY.should.is_a?(Enumerable)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/pop_spec.rb b/spec/ruby/library/readline/history/pop_spec.rb
index 3a4c3579d0..0b780a38cc 100644
--- a/spec/ruby/library/readline/history/pop_spec.rb
+++ b/spec/ruby/library/readline/history/pop_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 with_feature :readline do
   describe "Readline::HISTORY.pop" do
     it "returns nil when the history is empty" do
-      Readline::HISTORY.pop.should be_nil
+      Readline::HISTORY.pop.should == nil
     end
 
     it "returns and removes the last item from the history" do
@@ -19,12 +19,5 @@ with_feature :readline do
       Readline::HISTORY.pop.should == "1"
       Readline::HISTORY.size.should == 0
     end
-
-    it "taints the returned strings" do
-      Readline::HISTORY.push("1", "2", "3")
-      Readline::HISTORY.pop.tainted?.should be_true
-      Readline::HISTORY.pop.tainted?.should be_true
-      Readline::HISTORY.pop.tainted?.should be_true
-    end
   end
 end
diff --git a/spec/ruby/library/readline/history/push_spec.rb b/spec/ruby/library/readline/history/push_spec.rb
index 53505ccba6..4bbf1763a1 100644
--- a/spec/ruby/library/readline/history/push_spec.rb
+++ b/spec/ruby/library/readline/history/push_spec.rb
@@ -20,7 +20,7 @@ with_feature :readline do
     end
 
     it "raises a TypeError when the passed Object can't be converted to a String" do
-      -> { Readline::HISTORY.push(mock("Object")) }.should raise_error(TypeError)
+      -> { Readline::HISTORY.push(mock("Object")) }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/readline/history/shift_spec.rb b/spec/ruby/library/readline/history/shift_spec.rb
index fdc637fc35..d852480a2a 100644
--- a/spec/ruby/library/readline/history/shift_spec.rb
+++ b/spec/ruby/library/readline/history/shift_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 with_feature :readline do
   describe "Readline::HISTORY.shift" do
     it "returns nil when the history is empty" do
-      Readline::HISTORY.shift.should be_nil
+      Readline::HISTORY.shift.should == nil
     end
 
     it "returns and removes the first item from the history" do
@@ -19,12 +19,5 @@ with_feature :readline do
       Readline::HISTORY.shift.should == "3"
       Readline::HISTORY.size.should == 0
     end
-
-    it "taints the returned strings" do
-      Readline::HISTORY.push("1", "2", "3")
-      Readline::HISTORY.shift.tainted?.should be_true
-      Readline::HISTORY.shift.tainted?.should be_true
-      Readline::HISTORY.shift.tainted?.should be_true
-    end
   end
 end
diff --git a/spec/ruby/library/readline/readline_spec.rb b/spec/ruby/library/readline/readline_spec.rb
index f716d7b2df..6e349ad543 100644
--- a/spec/ruby/library/readline/readline_spec.rb
+++ b/spec/ruby/library/readline/readline_spec.rb
@@ -21,11 +21,6 @@ with_feature :readline do
         ruby_exe('File.write ARGV[0], Readline.readline', @options)
         File.read(@out).should == "test"
       end
-
-      it "taints the returned strings" do
-        ruby_exe('File.write ARGV[0], Readline.readline.tainted?', @options)
-        File.read(@out).should == "true"
-      end
     end
   end
 end
diff --git a/spec/ruby/library/readline/vi_editing_mode_spec.rb b/spec/ruby/library/readline/vi_editing_mode_spec.rb
index 6622962ceb..3ce4f5a7e6 100644
--- a/spec/ruby/library/readline/vi_editing_mode_spec.rb
+++ b/spec/ruby/library/readline/vi_editing_mode_spec.rb
@@ -4,7 +4,7 @@ platform_is_not :darwin do
   with_feature :readline do
     describe "Readline.vi_editing_mode" do
       it "returns nil" do
-        Readline.vi_editing_mode.should be_nil
+        Readline.vi_editing_mode.should == nil
       end
     end
   end
diff --git a/spec/ruby/library/resolv/get_address_spec.rb b/spec/ruby/library/resolv/get_address_spec.rb
index ecc2cdf7de..9caa94643a 100644
--- a/spec/ruby/library/resolv/get_address_spec.rb
+++ b/spec/ruby/library/resolv/get_address_spec.rb
@@ -14,6 +14,6 @@ describe "Resolv#getaddress" do
     res = Resolv.new([])
     -> {
       res.getaddress("should.raise.error.")
-    }.should raise_error(Resolv::ResolvError)
+    }.should.raise(Resolv::ResolvError)
   end
 end
diff --git a/spec/ruby/library/resolv/get_name_spec.rb b/spec/ruby/library/resolv/get_name_spec.rb
index 3ef97a2cea..81e0cda28d 100644
--- a/spec/ruby/library/resolv/get_name_spec.rb
+++ b/spec/ruby/library/resolv/get_name_spec.rb
@@ -13,6 +13,6 @@ describe "Resolv#getname" do
     res = Resolv.new([])
     -> {
       res.getname("should.raise.error")
-    }.should raise_error(Resolv::ResolvError)
+    }.should.raise(Resolv::ResolvError)
   end
 end
diff --git a/spec/ruby/library/rexml/attribute/clone_spec.rb b/spec/ruby/library/rexml/attribute/clone_spec.rb
deleted file mode 100644
index 9a4a4079e1..0000000000
--- a/spec/ruby/library/rexml/attribute/clone_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#clone" do
-  it "returns a copy of this Attribute" do
-    orig = REXML::Attribute.new("name", "value&&")
-    orig.should == orig.clone
-    orig.clone.to_s.should == orig.to_s
-    orig.clone.to_string.should == orig.to_string
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/element_spec.rb b/spec/ruby/library/rexml/attribute/element_spec.rb
deleted file mode 100644
index 832e7e9a41..0000000000
--- a/spec/ruby/library/rexml/attribute/element_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#element" do
-  it "returns the parent element" do
-    e = REXML::Element.new "root"
-
-    REXML::Attribute.new("name", "value", e).element.should == e
-    REXML::Attribute.new("name", "default_constructor").element.should == nil
-  end
-end
-
-describe "REXML::Attribute#element=" do
-  it "sets the parent element" do
-    e = REXML::Element.new "root"
-    f = REXML::Element.new "temp"
-    a = REXML::Attribute.new("name", "value", e)
-    a.element.should == e
-
-    a.element = f
-    a.element.should == f
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/equal_value_spec.rb b/spec/ruby/library/rexml/attribute/equal_value_spec.rb
deleted file mode 100644
index 8bf2c0a3a1..0000000000
--- a/spec/ruby/library/rexml/attribute/equal_value_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#==" do
-  it "returns true if other has equal name and value" do
-    a1 = REXML::Attribute.new("foo", "bar")
-    a1.should == a1.clone
-
-    a2 = REXML::Attribute.new("foo", "bar")
-    a1.should == a2
-
-    a3 = REXML::Attribute.new("foo", "bla")
-    a1.should_not == a3
-
-    a4 = REXML::Attribute.new("baz", "bar")
-    a1.should_not == a4
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/hash_spec.rb b/spec/ruby/library/rexml/attribute/hash_spec.rb
deleted file mode 100644
index dd71b28108..0000000000
--- a/spec/ruby/library/rexml/attribute/hash_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#hash" do
-  # These are not really complete, any idea on how to make them more
-  # "testable" will be appreciated.
-  it "returns a hashcode made of the name and value of self" do
-    a = REXML::Attribute.new("name", "value")
-    a.hash.should be_kind_of(Numeric)
-    b = REXML::Attribute.new(a)
-    a.hash.should == b.hash
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/initialize_spec.rb b/spec/ruby/library/rexml/attribute/initialize_spec.rb
deleted file mode 100644
index 9f5e30c517..0000000000
--- a/spec/ruby/library/rexml/attribute/initialize_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#initialize" do
-  before :each do
-    @e = REXML::Element.new "root"
-    @name = REXML::Attribute.new("name", "Nicko")
-    @e.add_attribute @name
-  end
-
-  it "receives two strings for name and value" do
-    @e.attributes["name"].should == "Nicko"
-    @e.add_attribute REXML::Attribute.new("last_name", nil)
-    @e.attributes["last_name"].should == ""
-  end
-
-  it "receives an Attribute and clones it" do
-    copy = REXML::Attribute.new(@name)
-    copy.should == @name
-  end
-
-  it "receives a parent node" do
-    last_name = REXML::Attribute.new("last_name", "McBrain", @e)
-    last_name.element.should == @e
-
-    last_name = REXML::Attribute.new(@name, @e)
-    last_name.element.should == @e
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/inspect_spec.rb b/spec/ruby/library/rexml/attribute/inspect_spec.rb
deleted file mode 100644
index 632b477cca..0000000000
--- a/spec/ruby/library/rexml/attribute/inspect_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#inspect" do
-  it "returns the name and value as a string" do
-    a = REXML::Attribute.new("my_name", "my_value")
-    a.inspect.should == "my_name='my_value'"
-  end
-
-  it "accepts attributes with no value" do
-    a = REXML::Attribute.new("my_name")
-    a.inspect.should == "my_name=''"
-  end
-
-  it "does not escape text" do
-    a = REXML::Attribute.new("name", "<>")
-    a.inspect.should == "name='<>'"
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/namespace_spec.rb b/spec/ruby/library/rexml/attribute/namespace_spec.rb
deleted file mode 100644
index 9d50770735..0000000000
--- a/spec/ruby/library/rexml/attribute/namespace_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#namespace" do
-  it "returns the namespace url" do
-    e = REXML::Element.new("root")
-    e.add_attribute REXML::Attribute.new("xmlns:ns", "http://some_uri")
-    e.namespace("ns").should == "http://some_uri"
-  end
-
-  it "returns nil if namespace is not defined" do
-    e = REXML::Element.new("root")
-    e.add_attribute REXML::Attribute.new("test", "value")
-    e.namespace("test").should == nil
-    e.namespace("ns").should == nil
-  end
-
-  it "defaults arg to nil" do
-    e = REXML::Element.new("root")
-    e.add_attribute REXML::Attribute.new("xmlns:ns", "http://some_uri")
-    e.namespace.should == ""
-    e.namespace("ns").should == "http://some_uri"
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/node_type_spec.rb b/spec/ruby/library/rexml/attribute/node_type_spec.rb
deleted file mode 100644
index 664d7cfa03..0000000000
--- a/spec/ruby/library/rexml/attribute/node_type_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#node_type" do
-  it "always returns :attribute" do
-    attr = REXML::Attribute.new("foo", "bar")
-    attr.node_type.should == :attribute
-    REXML::Attribute.new(attr).node_type.should == :attribute
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/prefix_spec.rb b/spec/ruby/library/rexml/attribute/prefix_spec.rb
deleted file mode 100644
index 2a47f74ad1..0000000000
--- a/spec/ruby/library/rexml/attribute/prefix_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#prefix" do
-  it "returns the namespace of the Attribute" do
-    ans = REXML::Attribute.new("ns:someattr", "some_value")
-    out = REXML::Attribute.new("out:something", "some_other_value")
-
-    ans.prefix.should == "ns"
-    out.prefix.should == "out"
-  end
-
-  it "returns an empty string for Attributes with no prefixes" do
-    attr = REXML::Attribute.new("foo", "bar")
-
-    attr.prefix.should == ""
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/remove_spec.rb b/spec/ruby/library/rexml/attribute/remove_spec.rb
deleted file mode 100644
index 08d22cb6ba..0000000000
--- a/spec/ruby/library/rexml/attribute/remove_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#remove" do
-  before :each do
-    @e = REXML::Element.new "Root"
-    @attr = REXML::Attribute.new("foo", "bar")
-  end
-
-  it "deletes this Attribute from parent" do
-    @e.add_attribute(@attr)
-    @e.attributes["foo"].should_not == nil
-    @attr.remove
-    @e.attributes["foo"].should == nil
-  end
-
-  it "does not anything if element has no parent" do
-    -> {@attr.remove}.should_not raise_error(Exception)
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/to_s_spec.rb b/spec/ruby/library/rexml/attribute/to_s_spec.rb
deleted file mode 100644
index e1ce48ec33..0000000000
--- a/spec/ruby/library/rexml/attribute/to_s_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#to_s" do
-  it "returns the value of the Attribute" do
-    REXML::Attribute.new("name", "some_value").to_s.should == "some_value"
-  end
-
-  it "returns the escaped value if it was created from Attribute" do
-    orig = REXML::Attribute.new("name", "<&>")
-    copy =  REXML::Attribute.new(orig)
-    copy.to_s.should == "&lt;&amp;&gt;"
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/to_string_spec.rb b/spec/ruby/library/rexml/attribute/to_string_spec.rb
deleted file mode 100644
index 420913afeb..0000000000
--- a/spec/ruby/library/rexml/attribute/to_string_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#to_string" do
-  it "returns the attribute as XML" do
-    attr = REXML::Attribute.new("name", "value")
-    attr_empty = REXML::Attribute.new("name")
-    attr_ns = REXML::Attribute.new("xmlns:ns", "http://uri")
-
-    attr.to_string.should == "name='value'"
-    attr_empty.to_string.should == "name=''"
-    attr_ns.to_string.should == "xmlns:ns='http://uri'"
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/value_spec.rb b/spec/ruby/library/rexml/attribute/value_spec.rb
deleted file mode 100644
index 7763976881..0000000000
--- a/spec/ruby/library/rexml/attribute/value_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#value" do
-  it "returns the value of the Attribute unnormalized" do
-    attr = REXML::Attribute.new("name", "value")
-    attr_ents = REXML::Attribute.new("name", "<&>")
-    attr_empty = REXML::Attribute.new("name")
-
-    attr.value.should == "value"
-    attr_ents.value.should == "<&>"
-    attr_empty.value.should == ""
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/write_spec.rb b/spec/ruby/library/rexml/attribute/write_spec.rb
deleted file mode 100644
index 7ada7460f9..0000000000
--- a/spec/ruby/library/rexml/attribute/write_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#write" do
-  before :each do
-    @attr = REXML::Attribute.new("name", "Charlotte")
-    @s = ""
-  end
-
-  it "writes the name and value to output" do
-    @attr.write(@s)
-    @s.should == "name='Charlotte'"
-  end
-
-  it "currently ignores the second argument" do
-    @attr.write(@s, 3)
-    @s.should == "name='Charlotte'"
-
-    @s = ""
-    @attr.write(@s, "foo")
-    @s.should == "name='Charlotte'"
-  end
-end
diff --git a/spec/ruby/library/rexml/attribute/xpath_spec.rb b/spec/ruby/library/rexml/attribute/xpath_spec.rb
deleted file mode 100644
index 8335e0a8ef..0000000000
--- a/spec/ruby/library/rexml/attribute/xpath_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attribute#xpath" do
-
-  before :each do
-    @e = REXML::Element.new "root"
-    @attr = REXML::Attribute.new("year", "1989")
-  end
-
-  it "returns the path for Attribute" do
-    @e.add_attribute @attr
-    @attr.xpath.should == "root/@year"
-  end
-
-  it "raises an error if attribute has no parent" do
-    -> { @attr.xpath }.should raise_error(Exception)
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/add_spec.rb b/spec/ruby/library/rexml/attributes/add_spec.rb
deleted file mode 100644
index 32a927e10b..0000000000
--- a/spec/ruby/library/rexml/attributes/add_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/add'
-require 'rexml/document'
-
-describe "REXML::Attributes#add" do
- it_behaves_like :rexml_attribute_add, :add
-end
diff --git a/spec/ruby/library/rexml/attributes/append_spec.rb b/spec/ruby/library/rexml/attributes/append_spec.rb
deleted file mode 100644
index f1b08f7d6a..0000000000
--- a/spec/ruby/library/rexml/attributes/append_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/add'
-require 'rexml/document'
-
-describe "REXML::Attributes#<<" do
- it_behaves_like :rexml_attribute_add, :<<
-end
diff --git a/spec/ruby/library/rexml/attributes/delete_all_spec.rb b/spec/ruby/library/rexml/attributes/delete_all_spec.rb
deleted file mode 100644
index 9340b5693b..0000000000
--- a/spec/ruby/library/rexml/attributes/delete_all_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#delete_all" do
-  before :each do
-    @e = REXML::Element.new("root")
-  end
-
-  it "deletes all attributes that match name" do
-    uri = REXML::Attribute.new("uri", "http://something")
-    @e.attributes << uri
-    @e.attributes.delete_all("uri")
-    @e.attributes.should be_empty
-    @e.attributes["uri"].should == nil
-  end
-
-  it "deletes all attributes that match name with a namespace" do
-    ns_uri = REXML::Attribute.new("xmlns:uri", "http://something_here_too")
-    @e.attributes << ns_uri
-    @e.attributes.delete_all("xmlns:uri")
-    @e.attributes.should be_empty
-    @e.attributes["xmlns:uri"].should == nil
-  end
-
-  it "returns the removed attribute" do
-    uri = REXML::Attribute.new("uri", "http://something_here_too")
-    @e.attributes << uri
-    attrs = @e.attributes.delete_all("uri")
-    attrs.first.should == uri
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/delete_spec.rb b/spec/ruby/library/rexml/attributes/delete_spec.rb
deleted file mode 100644
index 495e4085ef..0000000000
--- a/spec/ruby/library/rexml/attributes/delete_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#delete" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @name = REXML::Attribute.new("name", "Pepe")
-  end
-
-  it "takes an attribute name and deletes the attribute" do
-    @e.attributes.delete("name")
-    @e.attributes["name"].should be_nil
-    @e.attributes.should be_empty
-  end
-
-  it "takes an Attribute and deletes it" do
-    @e.attributes.delete(@name)
-    @e.attributes["name"].should be_nil
-    @e.attributes.should be_empty
-  end
-
-  it "returns the element with the attribute removed" do
-    ret_val = @e.attributes.delete(@name)
-    ret_val.should == @e
-    ret_val.attributes.should be_empty
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/each_attribute_spec.rb b/spec/ruby/library/rexml/attributes/each_attribute_spec.rb
deleted file mode 100644
index e84c8dbf51..0000000000
--- a/spec/ruby/library/rexml/attributes/each_attribute_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#each_attribute" do
-  it "iterates over the attributes yielding actual Attribute objects" do
-    e = REXML::Element.new("root")
-    name = REXML::Attribute.new("name", "Joe")
-    ns_uri = REXML::Attribute.new("xmlns:ns", "http://some_uri")
-    e.add_attribute name
-    e.add_attribute ns_uri
-
-    attributes = []
-
-    e.attributes.each_attribute do |attr|
-      attributes << attr
-    end
-
-    attributes = attributes.sort_by {|a| a.name }
-    attributes.first.should == name
-    attributes.last.should == ns_uri
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/each_spec.rb b/spec/ruby/library/rexml/attributes/each_spec.rb
deleted file mode 100644
index ed60634b90..0000000000
--- a/spec/ruby/library/rexml/attributes/each_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#each" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @name = REXML::Attribute.new("name", "Joe")
-    @ns_uri = REXML::Attribute.new("xmlns:ns", "http://some_uri")
-    @e.add_attribute @name
-    @e.add_attribute @ns_uri
-  end
-
-  it "iterates over the attributes yielding expanded-name/value" do
-    attributes = []
-    @e.attributes.each do |attr|
-      attr.should be_kind_of(Array)
-      attributes << attr
-    end
-    attributes = attributes.sort_by {|a| a.first }
-    attributes.first.should == ["name", "Joe"]
-    attributes.last.should == ["xmlns:ns", "http://some_uri"]
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/element_reference_spec.rb b/spec/ruby/library/rexml/attributes/element_reference_spec.rb
deleted file mode 100644
index dac7952669..0000000000
--- a/spec/ruby/library/rexml/attributes/element_reference_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#[]" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @lang = REXML::Attribute.new("language", "english")
-    @e.attributes << @lang
-  end
-
-  it "returns the value of an attribute" do
-    @e.attributes["language"].should == "english"
-  end
-
-  it "returns nil if the attribute does not exist" do
-    @e.attributes["chunky bacon"].should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/element_set_spec.rb b/spec/ruby/library/rexml/attributes/element_set_spec.rb
deleted file mode 100644
index 1ed94dd2a1..0000000000
--- a/spec/ruby/library/rexml/attributes/element_set_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#[]=" do
-  before :each do
-    @e = REXML::Element.new("song")
-    @name = REXML::Attribute.new("name", "Holy Smoke!")
-    @e.attributes << @name
-  end
-
-  it "sets an attribute" do
-    @e.attributes["author"] = "_why's foxes"
-    @e.attributes["author"].should == "_why's foxes"
-  end
-
-  it "overwrites an existing attribute" do
-    @e.attributes["name"] = "Chunky Bacon"
-    @e.attributes["name"].should == "Chunky Bacon"
-  end
-
-  it "deletes an attribute is value is nil" do
-    @e.attributes["name"] = nil
-    @e.attributes.length.should == 0
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/get_attribute_ns_spec.rb b/spec/ruby/library/rexml/attributes/get_attribute_ns_spec.rb
deleted file mode 100644
index 1664d6e42a..0000000000
--- a/spec/ruby/library/rexml/attributes/get_attribute_ns_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#get_attribute_ns" do
-  it "returns an attribute by name and namespace" do
-    e = REXML::Element.new("root")
-    attr = REXML::Attribute.new("xmlns:ns", "http://some_url")
-    e.attributes << attr
-    attr.prefix.should == "xmlns"
-    # This might be a bug in Attribute, commenting until those specs
-    # are ready
-    # e.attributes.get_attribute_ns(attr.prefix, "name").should == "http://some_url"
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/get_attribute_spec.rb b/spec/ruby/library/rexml/attributes/get_attribute_spec.rb
deleted file mode 100644
index cfe58c1b9e..0000000000
--- a/spec/ruby/library/rexml/attributes/get_attribute_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#get_attribute" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @name = REXML::Attribute.new("name", "Dave")
-    @e.attributes << @name
-  end
-
-  it "fetches an attributes" do
-    @e.attributes.get_attribute("name").should == @name
-  end
-
-  it "fetches an namespaced attribute" do
-    ns_name = REXML::Attribute.new("im:name", "Murray")
-    @e.attributes << ns_name
-    @e.attributes.get_attribute("name").should == @name
-    @e.attributes.get_attribute("im:name").should == ns_name
-  end
-
-  it "returns an Attribute" do
-    @e.attributes.get_attribute("name").should be_kind_of(REXML::Attribute)
-  end
-
-  it "returns nil if it attribute does not exist" do
-    @e.attributes.get_attribute("fake").should be_nil
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/initialize_spec.rb b/spec/ruby/library/rexml/attributes/initialize_spec.rb
deleted file mode 100644
index f18bd20c69..0000000000
--- a/spec/ruby/library/rexml/attributes/initialize_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#initialize" do
-  it "is auto initialized by Element" do
-    e = REXML::Element.new "root"
-    e.attributes.should be_kind_of(REXML::Attributes)
-
-    e.attributes << REXML::Attribute.new("name", "Paul")
-    e.attributes["name"].should == "Paul"
-  end
-
-  it "receives a parent node" do
-    e = REXML::Element.new "root"
-    e.attributes << REXML::Attribute.new("name", "Vic")
-    e.attributes["name"].should == "Vic"
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/length_spec.rb b/spec/ruby/library/rexml/attributes/length_spec.rb
deleted file mode 100644
index 3a8361b8d7..0000000000
--- a/spec/ruby/library/rexml/attributes/length_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/length'
-require 'rexml/document'
-
-describe "REXML::Attributes#length" do
- it_behaves_like :rexml_attribute_length, :length
-end
diff --git a/spec/ruby/library/rexml/attributes/namespaces_spec.rb b/spec/ruby/library/rexml/attributes/namespaces_spec.rb
deleted file mode 100644
index 9e329fef6f..0000000000
--- a/spec/ruby/library/rexml/attributes/namespaces_spec.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#namespaces" do
-  it "needs to be reviewed for spec completeness"
-end
diff --git a/spec/ruby/library/rexml/attributes/prefixes_spec.rb b/spec/ruby/library/rexml/attributes/prefixes_spec.rb
deleted file mode 100644
index 4675095aad..0000000000
--- a/spec/ruby/library/rexml/attributes/prefixes_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#prefixes" do
-  before :each do
-    @e = REXML::Element.new("root")
-    a1 = REXML::Attribute.new("xmlns:a", "bar")
-    a2 = REXML::Attribute.new("xmlns:b", "bla")
-    a3 = REXML::Attribute.new("xmlns:c", "baz")
-    @e.attributes << a1
-    @e.attributes << a2
-    @e.attributes << a3
-
-    @e.attributes << REXML::Attribute.new("xmlns", "foo")
-  end
-
-  it "returns an array with the prefixes of each attribute" do
-    @e.attributes.prefixes.sort.should == ["a", "b", "c"]
-  end
-
-  it "does not include the default namespace" do
-    @e.attributes.prefixes.include?("xmlns").should == false
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/shared/add.rb b/spec/ruby/library/rexml/attributes/shared/add.rb
deleted file mode 100644
index 872f149f45..0000000000
--- a/spec/ruby/library/rexml/attributes/shared/add.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-describe :rexml_attribute_add, shared: true do
-  before :each do
-    @e = REXML::Element.new("root")
-    @attr = REXML::Attributes.new(@e)
-    @name = REXML::Attribute.new("name", "Joe")
-  end
-
-  it "adds an attribute" do
-    @attr.send(@method, @name)
-    @attr["name"].should == "Joe"
-  end
-
-  it "replaces an existing attribute" do
-    @attr.send(@method, REXML::Attribute.new("name", "Bruce"))
-    @attr["name"].should == "Bruce"
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/shared/length.rb b/spec/ruby/library/rexml/attributes/shared/length.rb
deleted file mode 100644
index 7848f9bf33..0000000000
--- a/spec/ruby/library/rexml/attributes/shared/length.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'rexml/document'
-
-describe :rexml_attribute_length, shared: true do
-  it "returns the number of attributes" do
-    e = REXML::Element.new("root")
-    e.attributes.send(@method).should == 0
-
-    e.attributes << REXML::Attribute.new("name", "John")
-    e.attributes << REXML::Attribute.new("another_name", "Leo")
-    e.attributes.send(@method).should == 2
-  end
-end
diff --git a/spec/ruby/library/rexml/attributes/size_spec.rb b/spec/ruby/library/rexml/attributes/size_spec.rb
deleted file mode 100644
index 3b1df9510d..0000000000
--- a/spec/ruby/library/rexml/attributes/size_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/length'
-require 'rexml/document'
-
-describe "REXML::Attributes#size" do
- it_behaves_like :rexml_attribute_length, :size
-end
diff --git a/spec/ruby/library/rexml/attributes/to_a_spec.rb b/spec/ruby/library/rexml/attributes/to_a_spec.rb
deleted file mode 100644
index 1fbf71b683..0000000000
--- a/spec/ruby/library/rexml/attributes/to_a_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Attributes#to_a" do
-  it "returns an array with the attributes" do
-    e = REXML::Element.new("root")
-    name = REXML::Attribute.new("name", "Dave")
-    last = REXML::Attribute.new("last_name", "Murray")
-
-    e.attributes << name
-    e.attributes << last
-
-    e.attributes.to_a.sort{|a,b|a.to_s<=>b.to_s}.should == [name, last]
-  end
-
-  it "returns an empty array if it has no attributes" do
-    REXML::Element.new("root").attributes.to_a.should == []
-  end
-end
diff --git a/spec/ruby/library/rexml/cdata/clone_spec.rb b/spec/ruby/library/rexml/cdata/clone_spec.rb
deleted file mode 100644
index 7d3cfda902..0000000000
--- a/spec/ruby/library/rexml/cdata/clone_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::CData#clone" do
-  it "makes a copy of itself" do
-    c = REXML::CData.new("some text")
-    c.clone.to_s.should == c.to_s
-    c.clone.should == c
-  end
-end
diff --git a/spec/ruby/library/rexml/cdata/initialize_spec.rb b/spec/ruby/library/rexml/cdata/initialize_spec.rb
deleted file mode 100644
index 0184440d87..0000000000
--- a/spec/ruby/library/rexml/cdata/initialize_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::CData#initialize" do
-  it "creates a new CData object" do
-    c = REXML::CData.new("some    text")
-    c.should be_kind_of(REXML::CData)
-    c.should be_kind_of(REXML::Text)
-  end
-
-  it "respects whitespace if whitespace is true" do
-    c = REXML::CData.new("whitespace     test", true)
-    c1 = REXML::CData.new("whitespace     test", false)
-
-    c.to_s.should == "whitespace     test"
-    c1.to_s.should == "whitespace test"
-  end
-
-  it "receives parent as third argument" do
-    e = REXML::Element.new("root")
-    REXML::CData.new("test", true, e)
-    e.to_s.should == "<root><![CDATA[test]]></root>"
-  end
-end
diff --git a/spec/ruby/library/rexml/cdata/shared/to_s.rb b/spec/ruby/library/rexml/cdata/shared/to_s.rb
deleted file mode 100644
index f8c4951c95..0000000000
--- a/spec/ruby/library/rexml/cdata/shared/to_s.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-describe :rexml_cdata_to_s, shared: true do
-  it "returns the contents of the CData" do
-    c = REXML::CData.new("some text")
-    c.send(@method).should == "some text"
-  end
-
-  it "does not escape text" do
-    c1 = REXML::CData.new("some& text\n")
-    c1.send(@method).should == "some& text\n"
-  end
-end
diff --git a/spec/ruby/library/rexml/cdata/to_s_spec.rb b/spec/ruby/library/rexml/cdata/to_s_spec.rb
deleted file mode 100644
index ff3076e55e..0000000000
--- a/spec/ruby/library/rexml/cdata/to_s_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/to_s'
-require 'rexml/document'
-
-describe "REXML::CData#to_s" do
-  it_behaves_like :rexml_cdata_to_s, :to_s
-end
diff --git a/spec/ruby/library/rexml/cdata/value_spec.rb b/spec/ruby/library/rexml/cdata/value_spec.rb
deleted file mode 100644
index 6e8f8587a1..0000000000
--- a/spec/ruby/library/rexml/cdata/value_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/to_s'
-require 'rexml/document'
-
-describe "REXML::CData#value" do
-  it_behaves_like :rexml_cdata_to_s, :value
-end
diff --git a/spec/ruby/library/rexml/document/add_element_spec.rb b/spec/ruby/library/rexml/document/add_element_spec.rb
deleted file mode 100644
index 42981d6465..0000000000
--- a/spec/ruby/library/rexml/document/add_element_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#add_element" do
-  it "adds arg1 with attributes arg2 as root node" do
-    d = REXML::Document.new
-    e = REXML::Element.new("root")
-    d.add_element e
-    d.root.should == e
-  end
-
-  it "sets arg2 as arg1's attributes" do
-    d = REXML::Document.new
-    e = REXML::Element.new("root")
-    attr = {"foo" => "bar"}
-    d.add_element(e,attr)
-    d.root.attributes["foo"].should == attr["foo"]
-  end
-
-  it "accepts a node name as arg1 and adds it as root" do
-    d = REXML::Document.new
-    d.add_element "foo"
-    d.root.name.should == "foo"
-  end
-
-  it "sets arg1's context to the root's context" do
-    d = REXML::Document.new("", {"foo" => "bar"})
-    d.add_element "foo"
-    d.root.context.should == d.context
-  end
-end
diff --git a/spec/ruby/library/rexml/document/add_spec.rb b/spec/ruby/library/rexml/document/add_spec.rb
deleted file mode 100644
index db95114e7e..0000000000
--- a/spec/ruby/library/rexml/document/add_spec.rb
+++ /dev/null
@@ -1,57 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-# This spec defines Document#add and Document#<<
-
-describe :rexml_document_add, shared: true do
-  before :each do
-    @doc  = REXML::Document.new("<root/>")
-    @decl = REXML::XMLDecl.new("1.0")
-  end
-
-  it "sets document's XML declaration" do
-    @doc.send(@method, @decl)
-    @doc.xml_decl.should == @decl
-  end
-
-  it "inserts XML declaration as first node" do
-    @doc.send(@method, @decl)
-    @doc.children[0].version.should == "1.0"
-  end
-
-  it "overwrites existing XML declaration" do
-    @doc.send(@method, @decl)
-    @doc.send(@method, REXML::XMLDecl.new("2.0"))
-    @doc.xml_decl.version.should == "2.0"
-  end
-
-  it "sets document DocType" do
-    @doc.send(@method, REXML::DocType.new("transitional"))
-    @doc.doctype.name.should == "transitional"
-  end
-
-  it "overwrites existing DocType" do
-    @doc.send(@method, REXML::DocType.new("transitional"))
-    @doc.send(@method, REXML::DocType.new("strict"))
-    @doc.doctype.name.should == "strict"
-  end
-
-  it "adds root node unless it exists" do
-    d = REXML::Document.new("")
-    elem = REXML::Element.new "root"
-    d.send(@method, elem)
-    d.root.should == elem
-  end
-
-  it "refuses to add second root" do
-    -> { @doc.send(@method, REXML::Element.new("foo")) }.should raise_error(RuntimeError)
-  end
-end
-
-describe "REXML::Document#add" do
-  it_behaves_like :rexml_document_add, :add
-end
-
-describe "REXML::Document#<<" do
-  it_behaves_like :rexml_document_add, :<<
-end
diff --git a/spec/ruby/library/rexml/document/clone_spec.rb b/spec/ruby/library/rexml/document/clone_spec.rb
deleted file mode 100644
index 4aebb6f156..0000000000
--- a/spec/ruby/library/rexml/document/clone_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-# According to the MRI documentation (http://www.ruby-doc.org/stdlib/libdoc/rexml/rdoc/index.html),
-# clone's behavior "should be obvious". Apparently "obvious" means cloning
-# only the attributes and the context of the document, not its children.
-describe "REXML::Document#clone" do
-  it "clones document attributes" do
-    d = REXML::Document.new("foo")
-    d.attributes["foo"] = "bar"
-    e = d.clone
-    e.attributes.should == d.attributes
-  end
-
-  it "clones document context" do
-    d = REXML::Document.new("foo", {"foo" => "bar"})
-    e = d.clone
-    e.context.should == d.context
-  end
-end
diff --git a/spec/ruby/library/rexml/document/doctype_spec.rb b/spec/ruby/library/rexml/document/doctype_spec.rb
deleted file mode 100644
index b919b071e1..0000000000
--- a/spec/ruby/library/rexml/document/doctype_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#doctype" do
-  it "returns the doctype" do
-    d = REXML::Document.new
-    dt = REXML::DocType.new("foo")
-    d.add dt
-    d.doctype.should == dt
-  end
-
-  it "returns nil if there's no doctype" do
-    REXML::Document.new.doctype.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/document/encoding_spec.rb b/spec/ruby/library/rexml/document/encoding_spec.rb
deleted file mode 100644
index 343e0ee45f..0000000000
--- a/spec/ruby/library/rexml/document/encoding_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#encoding" do
-  before :each do
-    @doc = REXML::Document.new
-  end
-
-  it "returns encoding from XML declaration" do
-    @doc.add REXML::XMLDecl.new(nil, "UTF-16", nil)
-    @doc.encoding.should == "UTF-16"
-  end
-
-  it "returns encoding from XML declaration (for UTF-16 as well)" do
-    @doc.add REXML::XMLDecl.new("1.0", "UTF-8", nil)
-    @doc.encoding.should == "UTF-8"
-  end
-
-  it "uses UTF-8 as default encoding" do
-    @doc.encoding.should == "UTF-8"
-  end
-end
diff --git a/spec/ruby/library/rexml/document/expanded_name_spec.rb b/spec/ruby/library/rexml/document/expanded_name_spec.rb
deleted file mode 100644
index 1225d13fb0..0000000000
--- a/spec/ruby/library/rexml/document/expanded_name_spec.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe :document_expanded_name, shared: true do
-  it "returns an empty string for root" do # root nodes have no expanded name
-    REXML::Document.new.send(@method).should == ""
-  end
-end
-
-describe "REXML::Document#expanded_name" do
-  it_behaves_like :document_expanded_name, :expanded_name
-end
-
-describe "REXML::Document#name" do
-  it_behaves_like :document_expanded_name, :name
-end
diff --git a/spec/ruby/library/rexml/document/new_spec.rb b/spec/ruby/library/rexml/document/new_spec.rb
deleted file mode 100644
index 3ff5e99b25..0000000000
--- a/spec/ruby/library/rexml/document/new_spec.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Document#new" do
-
-  it "initializes context of {} unless specified" do
-    d = REXML::Document.new("<foo />")
-    d.context.should == {}
-  end
-
-  it "has empty attributes if source is nil" do
-    d = REXML::Document.new(nil)
-    d.elements.should be_empty
-  end
-
-  it "can use other document context" do
-    s = REXML::Document.new("")
-    d = REXML::Document.new(s)
-    d.context.should == s.context
-  end
-
-  it "clones source attributes" do
-    s = REXML::Document.new("<root />")
-    s.attributes["some_attr"] = "some_val"
-    d = REXML::Document.new(s)
-    d.attributes.should == s.attributes
-  end
-
-  it "raises an error if source is not a Document, String or IO" do
-    -> {REXML::Document.new(3)}.should raise_error(RuntimeError)
-  end
-
-  it "does not perform XML validation" do
-    REXML::Document.new("Invalid document").should be_kind_of(REXML::Document)
-  end
-end
diff --git a/spec/ruby/library/rexml/document/node_type_spec.rb b/spec/ruby/library/rexml/document/node_type_spec.rb
deleted file mode 100644
index 85a4d507aa..0000000000
--- a/spec/ruby/library/rexml/document/node_type_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#node_type" do
-  it "returns :document" do
-    REXML::Document.new.node_type.should == :document
-  end
-end
diff --git a/spec/ruby/library/rexml/document/root_spec.rb b/spec/ruby/library/rexml/document/root_spec.rb
deleted file mode 100644
index 3c24e79b2d..0000000000
--- a/spec/ruby/library/rexml/document/root_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#root" do
-  it "returns document root tag name" do
-    REXML::Document.new("<foo/>").root.name.should == "foo"
-  end
-
-  it "returns nil if there is not root" do
-    REXML::Document.new.root.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/document/stand_alone_spec.rb b/spec/ruby/library/rexml/document/stand_alone_spec.rb
deleted file mode 100644
index 4ac24329d6..0000000000
--- a/spec/ruby/library/rexml/document/stand_alone_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#stand_alone?" do
-  it "returns the XMLDecl standalone value" do
-    d = REXML::Document.new
-    decl = REXML::XMLDecl.new("1.0", "UTF-8", "yes")
-    d.add decl
-    d.stand_alone?.should == "yes"
-  end
-
-  # According to the docs this should return the default XMLDecl but that
-  # will carry some more problems when printing the document. Currently, it
-  # returns nil. See http://www.ruby-forum.com/topic/146812#650061
-  it "returns the default value when no XML declaration present" do
-    REXML::Document.new.stand_alone?.should == nil
-  end
-
-end
diff --git a/spec/ruby/library/rexml/document/version_spec.rb b/spec/ruby/library/rexml/document/version_spec.rb
deleted file mode 100644
index 983b4b9af0..0000000000
--- a/spec/ruby/library/rexml/document/version_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#version" do
-  it "returns XML version from declaration" do
-    d = REXML::Document.new
-    d.add REXML::XMLDecl.new("1.1")
-    d.version.should == "1.1"
-  end
-
-  it "returns the default version when declaration is not present" do
-    REXML::Document.new.version.should == REXML::XMLDecl::DEFAULT_VERSION
-  end
-end
diff --git a/spec/ruby/library/rexml/document/write_spec.rb b/spec/ruby/library/rexml/document/write_spec.rb
deleted file mode 100644
index efa94b7117..0000000000
--- a/spec/ruby/library/rexml/document/write_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require 'rexml/document'
-require 'rexml/formatters/transitive'
-require_relative '../../../spec_helper'
-
-# Maybe this can be cleaned
-describe "REXML::Document#write" do
-  before :each do
-    @d      = REXML::Document.new
-    city    = REXML::Element.new "Springfield"
-    street  = REXML::Element.new "EvergreenTerrace"
-    address = REXML::Element.new "House742"
-    @d << city << street << address
-    @str = ""
-  end
-
-  it "returns document source as string" do
-    @d.write(@str)
-    @str.should == "<Springfield><EvergreenTerrace><House742/></EvergreenTerrace></Springfield>"
-  end
-
-  it "returns document indented" do
-    @d.write(@str, 2)
-    @str.should =~ /\s*<Springfield>\s*<EvergreenTerrace>\s*<House742\/>\s*<\/EvergreenTerrace>\s*<\/Springfield>/
-  end
-
-  it "returns document with transitive support" do
-    @d.write(@str, 2, true)
-    @str.should =~ /\s*<Springfield\s*><EvergreenTerrace\s*><House742\s*\/><\/EvergreenTerrace\s*><\/Springfield\s*>/
-  end
-
-  it "returns document with support for IE" do
-    @d.write(@str, -1, false, true)
-    @str.should ==  "<Springfield><EvergreenTerrace><House742 /></EvergreenTerrace></Springfield>"
-  end
-end
diff --git a/spec/ruby/library/rexml/document/xml_decl_spec.rb b/spec/ruby/library/rexml/document/xml_decl_spec.rb
deleted file mode 100644
index 30288a150b..0000000000
--- a/spec/ruby/library/rexml/document/xml_decl_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Document#xml_decl" do
-  it "returns XML declaration of the document" do
-    d = REXML::Document.new
-    decl = REXML::XMLDecl.new("1.0", "UTF-16", "yes")
-    d.add decl
-    d.xml_decl.should == decl
-  end
-
-  it "returns default XML declaration unless present" do
-    REXML::Document.new.xml_decl.should == REXML::XMLDecl.new
-  end
-end
diff --git a/spec/ruby/library/rexml/element/add_attribute_spec.rb b/spec/ruby/library/rexml/element/add_attribute_spec.rb
deleted file mode 100644
index d15fb81ef1..0000000000
--- a/spec/ruby/library/rexml/element/add_attribute_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#add_attribute" do
-  before :each do
-    @person = REXML::Element.new "person"
-    @person.attributes["name"] = "Bill"
-  end
-
-  it "adds a new attribute" do
-    @person.add_attribute("age", "17")
-    @person.attributes["age"].should == "17"
-  end
-
-  it "overwrites an existing attribute" do
-    @person.add_attribute("name", "Bill")
-    @person.attributes["name"].should == "Bill"
-  end
-
-  it "accepts a pair of strings" do
-    @person.add_attribute("male", "true")
-    @person.attributes["male"].should == "true"
-  end
-
-  it "accepts an Attribute for key" do
-    attr = REXML::Attribute.new("male", "true")
-    @person.add_attribute attr
-    @person.attributes["male"].should == "true"
-  end
-
-  it "ignores value if key is an Attribute" do
-    attr = REXML::Attribute.new("male", "true")
-    @person.add_attribute(attr, "false")
-    @person.attributes["male"].should == "true"
-  end
-
-  it "returns the attribute added" do
-    attr = REXML::Attribute.new("name", "Tony")
-    @person.add_attribute(attr).should == attr
-  end
-end
diff --git a/spec/ruby/library/rexml/element/add_attributes_spec.rb b/spec/ruby/library/rexml/element/add_attributes_spec.rb
deleted file mode 100644
index b462fdf5fe..0000000000
--- a/spec/ruby/library/rexml/element/add_attributes_spec.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#add_attributes" do
-  before :each do
-    @person = REXML::Element.new "person"
-    @person.attributes["name"] = "Bill"
-  end
-
-  it "adds multiple attributes from a hash" do
-    @person.add_attributes({"name" => "Joe", "age" => "27"})
-    @person.attributes["name"].should == "Joe"
-    @person.attributes["age"].should == "27"
-  end
-
-  it "adds multiple attributes from an array" do
-    attrs =  { "name" => "Joe", "age" => "27"}
-    @person.add_attributes attrs.to_a
-    @person.attributes["name"].should == "Joe"
-    @person.attributes["age"].should == "27"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/add_element_spec.rb b/spec/ruby/library/rexml/element/add_element_spec.rb
deleted file mode 100644
index 8e2ffe3148..0000000000
--- a/spec/ruby/library/rexml/element/add_element_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-
-describe "REXML::Element#add_element" do
-  before :each do
-    @root = REXML::Element.new("root")
-  end
-
-  it "adds a child without attributes" do
-    name = REXML::Element.new("name")
-    @root.add_element name
-    @root.elements["name"].name.should == name.name
-    @root.elements["name"].attributes.should == name.attributes
-    @root.elements["name"].context.should == name.context
-  end
-
-  it "adds a child with attributes" do
-    person = REXML::Element.new("person")
-    @root.add_element(person, {"name" => "Madonna"})
-    @root.elements["person"].name.should == person.name
-    @root.elements["person"].attributes.should == person.attributes
-    @root.elements["person"].context.should == person.context
-  end
-
-  it "adds a child with name" do
-    @root.add_element "name"
-    @root.elements["name"].name.should == "name"
-    @root.elements["name"].attributes.should == {}
-    @root.elements["name"].context.should == nil
-  end
-
-  it "returns the added child" do
-    name = @root.add_element "name"
-    @root.elements["name"].name.should == name.name
-    @root.elements["name"].attributes.should == name.attributes
-    @root.elements["name"].context.should == name.context
-  end
-end
diff --git a/spec/ruby/library/rexml/element/add_namespace_spec.rb b/spec/ruby/library/rexml/element/add_namespace_spec.rb
deleted file mode 100644
index 77c00eec46..0000000000
--- a/spec/ruby/library/rexml/element/add_namespace_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#add_namespace" do
-  before :each do
-    @elem = REXML::Element.new("person")
-  end
-
-  it "adds a namespace to element" do
-    @elem.add_namespace("foo", "bar")
-    @elem.namespace("foo").should == "bar"
-  end
-
-  it "accepts a prefix string as prefix" do
-    @elem.add_namespace("xmlns:foo", "bar")
-    @elem.namespace("foo").should == "bar"
-  end
-
-  it "uses prefix as URI if uri is nil" do
-    @elem.add_namespace("some_uri", nil)
-    @elem.namespace.should == "some_uri"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/add_text_spec.rb b/spec/ruby/library/rexml/element/add_text_spec.rb
deleted file mode 100644
index 54e127bf4b..0000000000
--- a/spec/ruby/library/rexml/element/add_text_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#add_text" do
-  before :each do
-    @name = REXML::Element.new "Name"
-  end
-
-  it "adds text to an element" do
-    @name.add_text "Ringo"
-    @name.to_s.should == "<Name>Ringo</Name>"
-  end
-
-  it "accepts a Text" do
-    @name.add_text(REXML::Text.new("Ringo"))
-    @name.to_s.should == "<Name>Ringo</Name>"
-  end
-
-  it "joins the new text with the old one" do
-    @name.add_text "Ringo"
-    @name.add_text " Starr"
-    @name.to_s.should == "<Name>Ringo Starr</Name>"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/attribute_spec.rb b/spec/ruby/library/rexml/element/attribute_spec.rb
deleted file mode 100644
index e40d612ef3..0000000000
--- a/spec/ruby/library/rexml/element/attribute_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#attribute" do
-  it "returns an attribute by name" do
-    person = REXML::Element.new "Person"
-    attribute = REXML::Attribute.new("drink", "coffee")
-    person.add_attribute(attribute)
-    person.attribute("drink").should == attribute
-  end
-
-  it "supports attributes inside namespaces" do
-    e = REXML::Element.new("element")
-    e.add_attributes({"xmlns:ns" => "http://some_uri"})
-    e.attribute("ns", "ns").to_s.should == "http://some_uri"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/attributes_spec.rb b/spec/ruby/library/rexml/element/attributes_spec.rb
deleted file mode 100644
index 8959b769a8..0000000000
--- a/spec/ruby/library/rexml/element/attributes_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#attributes" do
-  it "returns element's Attributes" do
-    p = REXML::Element.new "Person"
-
-    name = REXML::Attribute.new("name", "John")
-    attrs = REXML::Attributes.new(p)
-    attrs.add name
-
-    p.add_attribute name
-    p.attributes.should == attrs
-  end
-
-  it "returns an empty hash if element has no attributes" do
-    REXML::Element.new("Person").attributes.should == {}
-  end
-end
diff --git a/spec/ruby/library/rexml/element/cdatas_spec.rb b/spec/ruby/library/rexml/element/cdatas_spec.rb
deleted file mode 100644
index a371a5734b..0000000000
--- a/spec/ruby/library/rexml/element/cdatas_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#cdatas" do
-  before :each do
-    @e = REXML::Element.new("Root")
-  end
-
-  it "returns the array of children cdatas" do
-    c = REXML::CData.new("Primary")
-    d = REXML::CData.new("Secondary")
-    @e << c
-    @e << d
-    @e.cdatas.should == [c, d]
-  end
-
-  it "freezes the returned array" do
-    @e.cdatas.frozen?.should == true
-  end
-
-  it "returns an empty array if element has no cdata" do
-    @e.cdatas.should == []
-  end
-end
diff --git a/spec/ruby/library/rexml/element/clone_spec.rb b/spec/ruby/library/rexml/element/clone_spec.rb
deleted file mode 100644
index d26392db41..0000000000
--- a/spec/ruby/library/rexml/element/clone_spec.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#clone" do
-  before :each do
-    @e = REXML::Element.new "a"
-  end
-  it "creates a copy of element" do
-    @e.clone.to_s.should == @e.to_s
-  end
-
-  it "copies the attributes" do
-    @e.add_attribute("foo", "bar")
-    @e.clone.to_s.should == @e.to_s
-  end
-
-  it "does not copy the text" do
-    @e.add_text "some text..."
-    @e.clone.to_s.should_not == @e
-    @e.clone.to_s.should == "<a/>"
-  end
-
-  it "does not copy the child elements" do
-    b = REXML::Element.new "b"
-    @e << b
-    @e.clone.should_not == @e
-    @e.clone.to_s.should == "<a/>"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/comments_spec.rb b/spec/ruby/library/rexml/element/comments_spec.rb
deleted file mode 100644
index 9dac2cc5b8..0000000000
--- a/spec/ruby/library/rexml/element/comments_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#comments" do
-  before :each do
-    @e = REXML::Element.new "root"
-    @c1 = REXML::Comment.new "this is a comment"
-    @c2 = REXML::Comment.new "this is another comment"
-    @e << @c1
-    @e << @c2
-  end
-
-  it "returns the array of comments" do
-    @e.comments.should == [@c1, @c2]
-  end
-
-  it "returns a frozen object" do
-    @e.comments.frozen?.should == true
-  end
-end
diff --git a/spec/ruby/library/rexml/element/delete_attribute_spec.rb b/spec/ruby/library/rexml/element/delete_attribute_spec.rb
deleted file mode 100644
index 5c55c5efda..0000000000
--- a/spec/ruby/library/rexml/element/delete_attribute_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#delete_attribute" do
-  before :each do
-    @e = REXML::Element.new("Person")
-    @attr = REXML::Attribute.new("name", "Sean")
-    @e.add_attribute(@attr)
-  end
-
-  it "deletes an attribute from the element" do
-    @e.delete_attribute("name")
-    @e.attributes["name"].should be_nil
-  end
-
-#  Bug was filled with a patch in Ruby's tracker #20298
-  quarantine! do
-    it "receives an Attribute" do
-      @e.add_attribute(@attr)
-      @e.delete_attribute(@attr)
-      @e.attributes["name"].should be_nil
-    end
-  end
-
-  # Docs say that it returns the removed attribute but then examples
-  # show it returns the element with the attribute removed.
-  # Also fixed in #20298
-  it "returns the element with the attribute removed" do
-    elem = @e.delete_attribute("name")
-    elem.attributes.should be_empty
-    elem.to_s.should eql("<Person/>")
-  end
-
-  it "returns nil if the attribute does not exist" do
-    @e.delete_attribute("name")
-    at = @e.delete_attribute("name")
-    at.should be_nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/delete_element_spec.rb b/spec/ruby/library/rexml/element/delete_element_spec.rb
deleted file mode 100644
index 9417229bd4..0000000000
--- a/spec/ruby/library/rexml/element/delete_element_spec.rb
+++ /dev/null
@@ -1,49 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#delete_element" do
-  before :each do
-    @root = REXML::Element.new("root")
-  end
-
-  it "deletes the child element" do
-    node = REXML::Element.new("some_node")
-    @root.add_element node
-    @root.delete_element node
-    @root.elements.size.should == 0
-  end
-
-  it "deletes a child via XPath" do
-    @root.add_element "some_node"
-    @root.delete_element "some_node"
-    @root.elements.size.should == 0
-  end
-
-  it "deletes the child at index" do
-    @root.add_element "some_node"
-    @root.delete_element 1
-    @root.elements.size.should == 0
-  end
-
-  # According to the docs this should return the deleted element
-  # but it won't if it's an Element.
-  it "deletes Element and returns it" do
-    node = REXML::Element.new("some_node")
-    @root.add_element node
-    del_node = @root.delete_element node
-    del_node.should == node
-  end
-
-  # Note how passing the string will return the removed element
-  # but passing the Element as above won't.
-  it "deletes an element and returns it" do
-    node = REXML::Element.new("some_node")
-    @root.add_element node
-    del_node = @root.delete_element "some_node"
-    del_node.should == node
-  end
-
-  it "returns nil unless element exists" do
-    @root.delete_element("something").should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/delete_namespace_spec.rb b/spec/ruby/library/rexml/element/delete_namespace_spec.rb
deleted file mode 100644
index 8683a40cab..0000000000
--- a/spec/ruby/library/rexml/element/delete_namespace_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#delete_namespace" do
-
-  before :each do
-    @doc = REXML::Document.new "<a xmlns:foo='bar' xmlns='twiddle'/>"
-  end
-
-  it "deletes a namespace from the element" do
-    @doc.root.delete_namespace 'foo'
-    @doc.root.namespace("foo").should be_nil
-    @doc.root.to_s.should == "<a xmlns='twiddle'/>"
-  end
-
-  it "deletes default namespace when called with no args" do
-    @doc.root.delete_namespace
-    @doc.root.namespace.should be_empty
-    @doc.root.to_s.should == "<a xmlns:foo='bar'/>"
-  end
-
-  it "returns the element" do
-    @doc.root.delete_namespace.should == @doc.root
-  end
-end
diff --git a/spec/ruby/library/rexml/element/document_spec.rb b/spec/ruby/library/rexml/element/document_spec.rb
deleted file mode 100644
index 24773580f2..0000000000
--- a/spec/ruby/library/rexml/element/document_spec.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#document" do
-
-  it "returns the element's document" do
-    d = REXML::Document.new("<root><elem/></root>")
-    d << REXML::XMLDecl.new
-    d.root.document.should == d
-    d.root.document.to_s.should == d.to_s
-  end
-
-  it "returns nil if it belongs to no document" do
-    REXML::Element.new("standalone").document.should be_nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/each_element_with_attribute_spec.rb b/spec/ruby/library/rexml/element/each_element_with_attribute_spec.rb
deleted file mode 100644
index 3c5da3f015..0000000000
--- a/spec/ruby/library/rexml/element/each_element_with_attribute_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#each_element_with_attributes" do
-  before :each do
-    @document = REXML::Element.new("people")
-    @father = REXML::Element.new("Person")
-    @father.attributes["name"] = "Joe"
-    @son = REXML::Element.new("Child")
-    @son.attributes["name"] = "Fred"
-    @document.root << @father
-    @document.root << @son
-    @childs = []
-  end
-
-  it "returns childs with attribute" do
-    @document.each_element_with_attribute("name") { |elem| @childs << elem }
-    @childs[0].should == @father
-    @childs[1].should == @son
-  end
-
-  it "takes attribute value as second argument" do
-    @document.each_element_with_attribute("name", "Fred"){ |elem| elem.should == @son }
-  end
-
-  it "takes max number of childs as third argument" do
-    @document.each_element_with_attribute("name", nil, 1) { |elem| @childs << elem }
-    @childs.size.should == 1
-    @childs[0].should == @father
-  end
-
-  it "takes XPath filter as fourth argument" do
-    @document.each_element_with_attribute("name", nil, 0, "Child"){ |elem| elem.should == @son}
-  end
-end
diff --git a/spec/ruby/library/rexml/element/each_element_with_text_spec.rb b/spec/ruby/library/rexml/element/each_element_with_text_spec.rb
deleted file mode 100644
index 5f9e5b85dc..0000000000
--- a/spec/ruby/library/rexml/element/each_element_with_text_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#each_element_with_text" do
-  before :each do
-    @document = REXML::Element.new("people")
-
-    @joe = REXML::Element.new("Person")
-    @joe.text = "Joe"
-    @fred = REXML::Element.new("Person")
-    @fred.text = "Fred"
-    @another = REXML::Element.new("AnotherPerson")
-    @another.text = "Fred"
-    @document.root << @joe
-    @document.root << @fred
-    @document.root << @another
-    @childs = []
-  end
-
-  it "returns childs with text" do
-    @document.each_element_with_text("Joe"){|c| c.should == @joe}
-  end
-
-  it "takes max as second argument" do
-    @document.each_element_with_text("Fred", 1){ |c| c.should == @fred}
-  end
-
-  it "takes XPath filter as third argument" do
-    @document.each_element_with_text("Fred", 0, "Person"){ |c| c.should == @fred}
-  end
-end
diff --git a/spec/ruby/library/rexml/element/element_reference_spec.rb b/spec/ruby/library/rexml/element/element_reference_spec.rb
deleted file mode 100644
index 9660ff7507..0000000000
--- a/spec/ruby/library/rexml/element/element_reference_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#[]" do
-
-  before :each do
-    @doc = REXML::Document.new("<root foo='bar'></root>")
-    @child = REXML::Element.new("child")
-    @doc.root.add_element @child
-  end
-
-  it "return attribute value if argument is string or symbol" do
-    @doc.root[:foo].should == 'bar'
-    @doc.root['foo'].should == 'bar'
-  end
-
-  it "return nth element if argument is int" do
-    @doc.root[0].should == @child
-  end
-end
diff --git a/spec/ruby/library/rexml/element/get_text_spec.rb b/spec/ruby/library/rexml/element/get_text_spec.rb
deleted file mode 100644
index 8ee9ea0824..0000000000
--- a/spec/ruby/library/rexml/element/get_text_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#get_text" do
-  before :each do
-    @doc = REXML::Document.new "<p>some text<b>this is bold!</b> more text</p>"
-  end
-
-  it "returns the first text child node" do
-    @doc.root.get_text.value.should == "some text"
-    @doc.root.get_text.should be_kind_of(REXML::Text)
-  end
-
-  it "returns text from an element matching path" do
-    @doc.root.get_text("b").value.should == "this is bold!"
-    @doc.root.get_text("b").should be_kind_of(REXML::Text)
-  end
-end
diff --git a/spec/ruby/library/rexml/element/has_attributes_spec.rb b/spec/ruby/library/rexml/element/has_attributes_spec.rb
deleted file mode 100644
index f89ec675f5..0000000000
--- a/spec/ruby/library/rexml/element/has_attributes_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#has_attributes?" do
-  before :each do
-    @e = REXML::Element.new("test_elem")
-  end
-
-  it "returns true when element has any attributes" do
-    @e.add_attribute("name", "Joe")
-    @e.has_attributes?.should be_true
-  end
-
-  it "returns false if element has no attributes" do
-    @e.has_attributes?.should be_false
-  end
-end
diff --git a/spec/ruby/library/rexml/element/has_elements_spec.rb b/spec/ruby/library/rexml/element/has_elements_spec.rb
deleted file mode 100644
index dc5fc9c25b..0000000000
--- a/spec/ruby/library/rexml/element/has_elements_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#has_elements?" do
-  before :each do
-    @e = REXML::Element.new("root")
-  end
-
-  it "returns true if element has child elements" do
-    child = REXML::Element.new("child")
-    @e << child
-    @e.has_elements?.should be_true
-  end
-
-  it "returns false if element doesn't have child elements" do
-    @e.has_elements?.should be_false
-  end
-end
diff --git a/spec/ruby/library/rexml/element/has_text_spec.rb b/spec/ruby/library/rexml/element/has_text_spec.rb
deleted file mode 100644
index e9d5a176cb..0000000000
--- a/spec/ruby/library/rexml/element/has_text_spec.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#has_text?" do
-
-  it "returns true if element has a Text child" do
-    e = REXML::Element.new("Person")
-    e.text = "My text"
-    e.has_text?.should be_true
-  end
-
-  it "returns false if it has no Text childs" do
-    e = REXML::Element.new("Person")
-    e.has_text?.should be_false
-  end
-end
diff --git a/spec/ruby/library/rexml/element/inspect_spec.rb b/spec/ruby/library/rexml/element/inspect_spec.rb
deleted file mode 100644
index f45edd0b1f..0000000000
--- a/spec/ruby/library/rexml/element/inspect_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#inspect" do
-
-  before :each do
-    @name = REXML::Element.new "name"
-  end
-
-  it "returns the node as a string" do
-    @name.inspect.should == "<name/>"
-  end
-
-  it "inserts '...' if the node has children" do
-    e = REXML::Element.new "last_name"
-    @name << e
-    @name.inspect.should == "<name> ... </>"
-    # This might make more sense but differs from MRI's default behavior
-    # @name.inspect.should == "<name> ... </name>"
-  end
-
-  it "inserts the attributes in the string" do
-    @name.add_attribute "language"
-    @name.attributes["language"] = "english"
-    @name.inspect.should == "<name language='english'/>"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/instructions_spec.rb b/spec/ruby/library/rexml/element/instructions_spec.rb
deleted file mode 100644
index aa2d192e7c..0000000000
--- a/spec/ruby/library/rexml/element/instructions_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#instructions" do
-  before :each do
-    @elem = REXML::Element.new("root")
-  end
-  it "returns the Instruction children nodes" do
-    inst = REXML::Instruction.new("xml-stylesheet", "href='headlines.css'")
-    @elem << inst
-    @elem.instructions.first.should == inst
-  end
-
-  it "returns an empty array if it has no Instruction children" do
-    @elem.instructions.should be_empty
-  end
-
-  it "freezes the returned array" do
-    @elem.instructions.frozen?.should be_true
-  end
-end
diff --git a/spec/ruby/library/rexml/element/namespace_spec.rb b/spec/ruby/library/rexml/element/namespace_spec.rb
deleted file mode 100644
index 89662f3599..0000000000
--- a/spec/ruby/library/rexml/element/namespace_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#namespace" do
-  before :each do
-    @doc = REXML::Document.new("<a xmlns='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
-    @elem = @doc.elements["//b"]
-  end
-
-  it "returns the default namespace" do
-    @elem.namespace.should == "1"
-  end
-
-  it "accepts a namespace prefix" do
-    @elem.namespace("y").should == "2"
-    @doc.elements["//c"].namespace("z").should == "3"
-  end
-
-  it "returns an empty String if default namespace is not defined" do
-    e = REXML::Document.new("<a/>")
-    e.root.namespace.should be_empty
-  end
-
-  it "returns nil if namespace is not defined" do
-    @elem.namespace("z").should be_nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/namespaces_spec.rb b/spec/ruby/library/rexml/element/namespaces_spec.rb
deleted file mode 100644
index a84c1d1dab..0000000000
--- a/spec/ruby/library/rexml/element/namespaces_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#namespaces" do
-  before :each do
-    doc = REXML::Document.new("<a xmlns='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
-    @elem = doc.elements["//c"]
-  end
-
-  it "returns a hash of the namespaces" do
-    ns = {"y"=>"2", "z"=>"3", "xmlns"=>"1"}
-    @elem.namespaces.keys.sort.should == ns.keys.sort
-    @elem.namespaces.values.sort.should == ns.values.sort
-  end
-
-  it "returns an empty hash if no namespaces exist" do
-    e = REXML::Element.new "element"
-    e.namespaces.kind_of?(Hash).should == true
-    e.namespaces.should be_empty
-  end
-
-  it "uses namespace prefixes as keys" do
-    prefixes = ["y", "z", "xmlns"]
-    @elem.namespaces.keys.sort.should == prefixes.sort
-  end
-
-  it "uses namespace values as the hash values" do
-    values = ["2", "3", "1"]
-    @elem.namespaces.values.sort.should == values.sort
-  end
-
-end
diff --git a/spec/ruby/library/rexml/element/new_spec.rb b/spec/ruby/library/rexml/element/new_spec.rb
deleted file mode 100644
index 4ffdf4dabe..0000000000
--- a/spec/ruby/library/rexml/element/new_spec.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#new" do
-
-  it "creates element from tag name" do
-    REXML::Element.new("foo").name.should == "foo"
-  end
-
-  it "creates element with default attributes" do
-    e = REXML::Element.new
-    e.name.should == REXML::Element::UNDEFINED
-    e.context.should == nil
-    e.parent.should == nil
-  end
-
-  it "creates element from another element" do
-    e = REXML::Element.new "foo"
-    f = REXML::Element.new e
-    e.name.should == f.name
-    e.context.should == f.context
-    e.parent.should == f.parent
-  end
-
-  it "takes parent as second argument" do
-    parent = REXML::Element.new "foo"
-    child = REXML::Element.new "bar", parent
-    child.parent.should == parent
-  end
-
-  it "takes context as third argument" do
-    context = {"some_key" => "some_value"}
-    REXML::Element.new("foo", nil, context).context.should == context
-  end
-end
diff --git a/spec/ruby/library/rexml/element/next_element_spec.rb b/spec/ruby/library/rexml/element/next_element_spec.rb
deleted file mode 100644
index 5b6d6cad9b..0000000000
--- a/spec/ruby/library/rexml/element/next_element_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#next_element" do
-  before :each do
-    @a = REXML::Element.new "a"
-    @b = REXML::Element.new "b"
-    @c = REXML::Element.new "c"
-    @a.root << @b
-    @a.root << @c
-  end
-  it "returns next existing element" do
-    @a.elements["b"].next_element.should == @c
-  end
-
-  it "returns nil on last element" do
-    @a.elements["c"].next_element.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/node_type_spec.rb b/spec/ruby/library/rexml/element/node_type_spec.rb
deleted file mode 100644
index bcab9e126d..0000000000
--- a/spec/ruby/library/rexml/element/node_type_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#node_type" do
-  it "returns :element" do
-    REXML::Element.new("MyElem").node_type.should == :element
-  end
-end
diff --git a/spec/ruby/library/rexml/element/prefixes_spec.rb b/spec/ruby/library/rexml/element/prefixes_spec.rb
deleted file mode 100644
index b6edf9a847..0000000000
--- a/spec/ruby/library/rexml/element/prefixes_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#prefixes" do
-  before :each do
-    doc = REXML::Document.new("<a xmlns='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
-    @elem = doc.elements["//c"]
-  end
-
-  it "returns an array of the prefixes of the namespaces" do
-    @elem.prefixes.should == ["y", "z"]
-  end
-
-  it "does not include the default namespace" do
-    @elem.prefixes.include?("xmlns").should == false
-  end
-
-  it "returns an empty array if no namespace was defined" do
-    doc = REXML::Document.new "<root><something/></root>"
-    root = doc.elements["//root"]
-    root.prefixes.should == []
-  end
-end
diff --git a/spec/ruby/library/rexml/element/previous_element_spec.rb b/spec/ruby/library/rexml/element/previous_element_spec.rb
deleted file mode 100644
index 2fe79d955f..0000000000
--- a/spec/ruby/library/rexml/element/previous_element_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#previous_element" do
-  before :each do
-    @a = REXML::Element.new "a"
-    @b = REXML::Element.new "b"
-    @c = REXML::Element.new "c"
-    @a.root << @b
-    @a.root << @c
-  end
-
-  it "returns previous element" do
-    @a.elements["c"].previous_element.should == @b
-  end
-
-  it "returns nil on first element" do
-    @a.elements["b"].previous_element.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/raw_spec.rb b/spec/ruby/library/rexml/element/raw_spec.rb
deleted file mode 100644
index 404ccce5f4..0000000000
--- a/spec/ruby/library/rexml/element/raw_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#raw" do
-  it "returns true if raw mode is set to all" do
-    REXML::Element.new("MyElem", nil, {raw: :all}).raw.should == true
-  end
-
-  it "returns true if raw mode is set to expanded_name" do
-    REXML::Element.new("MyElem", nil, {raw: "MyElem"}).raw.should == true
-  end
-
-  it "returns false if raw mode is not set" do
-    REXML::Element.new("MyElem", nil, {raw: ""}).raw.should == false
-  end
-
-  it "returns false if raw is not :all or expanded_name" do
-    REXML::Element.new("MyElem", nil, {raw: "Something"}).raw.should == false
-  end
-
-  it "returns nil if context is not set" do
-    REXML::Element.new("MyElem").raw.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/element/root_spec.rb b/spec/ruby/library/rexml/element/root_spec.rb
deleted file mode 100644
index 1e0669033e..0000000000
--- a/spec/ruby/library/rexml/element/root_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Element#root" do
-  before :each do
-    @doc  = REXML::Document.new
-    @root = REXML::Element.new "root"
-    @node = REXML::Element.new "node"
-    @doc << @root << @node
-  end
-
-  it "returns first child on documents" do
-    @doc.root.should == @root
-  end
-
-  it "returns self on root nodes" do
-    @root.root.should == @root
-  end
-
-  it "returns parent's root on child nodes" do
-    @node.root.should == @root
-  end
-
-  it "returns self on standalone nodes" do
-    e = REXML::Element.new "Elem"         # Note that it doesn't have a parent node
-    e.root.should == e
-  end
-end
diff --git a/spec/ruby/library/rexml/element/text_spec.rb b/spec/ruby/library/rexml/element/text_spec.rb
deleted file mode 100644
index 7c290c4cda..0000000000
--- a/spec/ruby/library/rexml/element/text_spec.rb
+++ /dev/null
@@ -1,46 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#text" do
-  before :each do
-    @e = REXML::Element.new "name"
-    @e.text = "John"
-  end
-
-  it "returns the text node of element" do
-    @e.text.should == "John"
-  end
-
-  it "returns the text node value" do
-    t = REXML::Text.new "Joe"
-    @e.text = t
-    @e.text.should == "Joe"
-    @e.text.should_not == t
-  end
-
-  it "returns nil if no text is attached" do
-    elem = REXML::Element.new "name"
-    elem.text.should == nil
-  end
-end
-
-describe "REXML::Element#text=" do
-  before :each do
-    @e = REXML::Element.new "name"
-    @e.text = "John"
-  end
-
-  it "sets the text node" do
-    @e.to_s.should == "<name>John</name>"
-  end
-
-  it "replaces existing text" do
-    @e.text = "Joe"
-    @e.to_s.should == "<name>Joe</name>"
-  end
-
-  it "receives nil as an argument" do
-    @e.text = nil
-    @e.to_s.should == "<name/>"
-  end
-end
diff --git a/spec/ruby/library/rexml/element/texts_spec.rb b/spec/ruby/library/rexml/element/texts_spec.rb
deleted file mode 100644
index 7975833c89..0000000000
--- a/spec/ruby/library/rexml/element/texts_spec.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#texts" do
-
-  it "returns an array of the Text children" do
-    e = REXML::Element.new("root")
-    e.add_text "First"
-    e.add_text "Second"
-    e.texts.should == ["FirstSecond"]
-  end
-
-  it "returns an empty array if it has no Text children" do
-    REXML::Element.new("root").texts.should == []
-  end
-end
diff --git a/spec/ruby/library/rexml/element/whitespace_spec.rb b/spec/ruby/library/rexml/element/whitespace_spec.rb
deleted file mode 100644
index dc785ae5ce..0000000000
--- a/spec/ruby/library/rexml/element/whitespace_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe "REXML::Element#whitespace" do
-  it "returns true if whitespace is respected in the element" do
-    e = REXML::Element.new("root")
-    e.whitespace.should be_true
-
-    e = REXML::Element.new("root", nil, respect_whitespace: :all)
-    e.whitespace.should be_true
-
-    e = REXML::Element.new("root", nil, respect_whitespace: ["root"])
-    e.whitespace.should be_true
-  end
-
-  it "returns false if whitespace is ignored inside element" do
-    e = REXML::Element.new("root", nil, compress_whitespace: :all)
-    e.whitespace.should be_false
-
-    e = REXML::Element.new("root", nil, compress_whitespace: ["root"])
-    e.whitespace.should be_false
-  end
-end
diff --git a/spec/ruby/library/rexml/node/each_recursive_spec.rb b/spec/ruby/library/rexml/node/each_recursive_spec.rb
deleted file mode 100644
index dd4aa9a2f2..0000000000
--- a/spec/ruby/library/rexml/node/each_recursive_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#each_recursive" do
-  before :each do
-    @doc = REXML::Document.new
-    @doc << REXML::XMLDecl.new
-    @root = REXML::Element.new "root"
-    @child1 = REXML::Element.new "child1"
-    @child2 = REXML::Element.new "child2"
-    @root << @child1
-    @root << @child2
-    @doc << @root
-  end
-
-  it "visits all subnodes of self" do
-    nodes = []
-    @doc.each_recursive { |node| nodes << node}
-    nodes.should == [@root, @child1, @child2]
-  end
-end
diff --git a/spec/ruby/library/rexml/node/find_first_recursive_spec.rb b/spec/ruby/library/rexml/node/find_first_recursive_spec.rb
deleted file mode 100644
index ba46f2ca35..0000000000
--- a/spec/ruby/library/rexml/node/find_first_recursive_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#find_first_recursive" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @node1 = REXML::Element.new("node")
-    @node2 = REXML::Element.new("another node")
-    @subnode = REXML::Element.new("another node")
-    @node1 << @subnode
-    @e << @node1
-    @e << @node2
-  end
-
-  it "finds the first element that matches block" do
-    found = @e.find_first_recursive { |n| n.to_s == "<node><another node/></node>"}
-    found.should == @node1
-  end
-
-  it "visits the nodes in preorder" do
-    found = @e.find_first_recursive { |n| n.to_s == "<another node/>"}
-    found.should == @subnode
-    found.should_not == @node2
-  end
-end
diff --git a/spec/ruby/library/rexml/node/index_in_parent_spec.rb b/spec/ruby/library/rexml/node/index_in_parent_spec.rb
deleted file mode 100644
index 092851e3e7..0000000000
--- a/spec/ruby/library/rexml/node/index_in_parent_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#index_in_parent" do
-  it "returns the index (starting from 1) of self in parent" do
-    e = REXML::Element.new("root")
-    node1 = REXML::Element.new("node")
-    node2 = REXML::Element.new("another node")
-    e << node1
-    e << node2
-
-    node1.index_in_parent.should == 1
-    node2.index_in_parent.should == 2
-  end
-end
diff --git a/spec/ruby/library/rexml/node/next_sibling_node_spec.rb b/spec/ruby/library/rexml/node/next_sibling_node_spec.rb
deleted file mode 100644
index 2e8601627d..0000000000
--- a/spec/ruby/library/rexml/node/next_sibling_node_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#next_sibling_node" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @node1 = REXML::Element.new("node")
-    @node2 = REXML::Element.new("another node")
-    @e << @node1
-    @e << @node2
-  end
-
-  it "returns the next child node in parent" do
-    @node1.next_sibling_node.should == @node2
-  end
-
-  it "returns nil if there are no more child nodes next" do
-    @node2.next_sibling_node.should == nil
-    @e.next_sibling_node.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/node/parent_spec.rb b/spec/ruby/library/rexml/node/parent_spec.rb
deleted file mode 100644
index d88ba69657..0000000000
--- a/spec/ruby/library/rexml/node/parent_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#parent?" do
-  it "returns true for Elements" do
-    e = REXML::Element.new("foo")
-    e.parent?.should == true
-  end
-
-  it "returns true for Documents" do
-    e = REXML::Document.new
-    e.parent?.should == true
-  end
-
-  # This includes attributes, CDatas and declarations.
-  it "returns false for Texts" do
-    e = REXML::Text.new("foo")
-    e.parent?.should == false
-  end
-end
diff --git a/spec/ruby/library/rexml/node/previous_sibling_node_spec.rb b/spec/ruby/library/rexml/node/previous_sibling_node_spec.rb
deleted file mode 100644
index 8b96f1565a..0000000000
--- a/spec/ruby/library/rexml/node/previous_sibling_node_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Node#previous_sibling_node" do
-  before :each do
-    @e = REXML::Element.new("root")
-    @node1 = REXML::Element.new("node")
-    @node2 = REXML::Element.new("another node")
-    @e << @node1
-    @e << @node2
-  end
-
-  it "returns the previous child node in parent" do
-    @node2.previous_sibling_node.should == @node1
-  end
-
-  it "returns nil if there are no more child nodes before" do
-    @node1.previous_sibling_node.should == nil
-    @e.previous_sibling_node.should == nil
-  end
-end
diff --git a/spec/ruby/library/rexml/shared/each_element.rb b/spec/ruby/library/rexml/shared/each_element.rb
deleted file mode 100644
index 2e0871161d..0000000000
--- a/spec/ruby/library/rexml/shared/each_element.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe :rexml_each_element, shared: true do
-  before :each do
-    @e = REXML::Element.new "root"
-    s1 = REXML::Element.new "node1"
-    s2 = REXML::Element.new "node2"
-    s3 = REXML::Element.new "node3"
-    s4 = REXML::Element.new "sub_node"
-    @e << s1
-    @e << s2
-    @e << s3
-    @e << s4
-  end
-
-  it "iterates through element" do
-    str = ""
-      @e.send(@method) { |elem| str << elem.name << " " }
-    str.should == "node1 node2 node3 sub_node "
-  end
-
-  it "iterates through element filtering with XPath" do
-    str = ""
-     @e.send(@method, "/*"){ |e| str << e.name << " "}
-     str.should == "node1 node2 node3 sub_node "
-  end
-end
-
-describe "REXML::Element#each_element" do
- it_behaves_like :rexml_each_element, :each_element
-end
-
-describe "REXML::Elements#each" do
-  it_behaves_like :rexml_each_element, :each
-end
diff --git a/spec/ruby/library/rexml/shared/elements_to_a.rb b/spec/ruby/library/rexml/shared/elements_to_a.rb
deleted file mode 100644
index 388250d8b3..0000000000
--- a/spec/ruby/library/rexml/shared/elements_to_a.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require 'rexml/document'
-require_relative '../../../spec_helper'
-
-describe :rexml_elements_to_a, shared: true do
-  before :each do
-    @e = REXML::Element.new "root"
-    @first = REXML::Element.new("FirstChild")
-    @second = REXML::Element.new("SecondChild")
-    @e << @first
-    @e << @second
-  end
-
-  it "returns elements that match xpath" do
-    @e.elements.send(@method, "FirstChild").first.should == @first
-  end
-
-  # According to the docs REXML::Element#get_elements is an alias for
-  # REXML::Elements.to_a. Implementation wise there's a difference, get_elements
-  # always needs the first param (even if it's nil).
-  # A patch was submitted:
-  # http://rubyforge.org/tracker/index.php?func=detail&aid=19354&group_id=426&atid=1698
-  it "returns all childs if xpath is nil" do
-    @e.elements.send(@method).should == [@first, @second]
-  end
-
-end
-
-describe "REXML::REXML::Elements#to_a" do
-  it_behaves_like :rexml_elements_to_a, :to_a
-end
-
-describe "REXML::REXML::Element#get_elements" do
-  it_behaves_like :rexml_elements_to_a, :get_elements
-end
diff --git a/spec/ruby/library/rexml/text/append_spec.rb b/spec/ruby/library/rexml/text/append_spec.rb
deleted file mode 100644
index de281fb0b0..0000000000
--- a/spec/ruby/library/rexml/text/append_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#<<" do
-  it "appends a string to this text node" do
-    text = REXML::Text.new("foo")
-    text << "bar"
-    text.should == "foobar"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/clone_spec.rb b/spec/ruby/library/rexml/text/clone_spec.rb
deleted file mode 100644
index 8031e140c7..0000000000
--- a/spec/ruby/library/rexml/text/clone_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#clone" do
-  it "creates a copy of this node" do
-    text = REXML::Text.new("foo")
-    text.clone.should == "foo"
-    text.clone.should == text
-  end
-end
diff --git a/spec/ruby/library/rexml/text/comparison_spec.rb b/spec/ruby/library/rexml/text/comparison_spec.rb
deleted file mode 100644
index 8bc5d66a03..0000000000
--- a/spec/ruby/library/rexml/text/comparison_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#<=>" do
-  before :each do
-    @first = REXML::Text.new("abc")
-    @last = REXML::Text.new("def")
-  end
-
-  it "returns -1 if lvalue is less than rvalue" do
-    val = @first <=> @last
-    val.should == -1
-  end
-
-  it "returns -1 if lvalue is greater than rvalue" do
-    val = @last <=> @first
-    val.should == 1
-  end
-
-  it "returns 0 if both values are equal" do
-    tmp = REXML::Text.new("tmp")
-    val = tmp <=> tmp
-    val.should == 0
-  end
-end
diff --git a/spec/ruby/library/rexml/text/empty_spec.rb b/spec/ruby/library/rexml/text/empty_spec.rb
deleted file mode 100644
index d0b66b7a2a..0000000000
--- a/spec/ruby/library/rexml/text/empty_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#empty?" do
-  it "returns true if the text is empty" do
-    REXML::Text.new("").empty?.should == true
-  end
-
-  it "returns false if the text is not empty" do
-    REXML::Text.new("some_text").empty?.should == false
-  end
-end
diff --git a/spec/ruby/library/rexml/text/indent_text_spec.rb b/spec/ruby/library/rexml/text/indent_text_spec.rb
deleted file mode 100644
index 1b0ee5ab16..0000000000
--- a/spec/ruby/library/rexml/text/indent_text_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#indent_text" do
-  before :each do
-    @t = REXML::Text.new("")
-  end
-  it "indents a string with default parameters" do
-    @t.indent_text("foo").should == "\tfoo"
-  end
-
-  it "accepts a custom indentation level as second argument" do
-    @t.indent_text("foo", 2, "\t", true).should == "\t\tfoo"
-  end
-
-  it "accepts a custom separator as third argument" do
-    @t.indent_text("foo", 1, "\n", true).should == "\nfoo"
-  end
-
-  it "accepts a fourth parameter to skip the first line" do
-    @t.indent_text("foo", 1, "\t", false).should == "foo"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/inspect_spec.rb b/spec/ruby/library/rexml/text/inspect_spec.rb
deleted file mode 100644
index 0d66088a64..0000000000
--- a/spec/ruby/library/rexml/text/inspect_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#inspect" do
-  it "inspects the string attribute as a string" do
-    REXML::Text.new("a text").inspect.should == "a text".inspect
-  end
-end
diff --git a/spec/ruby/library/rexml/text/new_spec.rb b/spec/ruby/library/rexml/text/new_spec.rb
deleted file mode 100644
index 3c081dec30..0000000000
--- a/spec/ruby/library/rexml/text/new_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text.new" do
-
-  it "creates a Text child node with no parent" do
-    t = REXML::Text.new("test")
-    t.should be_kind_of(REXML::Child)
-    t.should == "test"
-    t.parent.should == nil
-  end
-
-  it "respects whitespace if second argument is true" do
-    t = REXML::Text.new("testing   whitespace", true)
-    t.should == "testing   whitespace"
-    t = REXML::Text.new("   ", true)
-    t.should == "   "
-  end
-
-  it "receives a parent as third argument" do
-    e = REXML::Element.new("root")
-    t = REXML::Text.new("test", false, e)
-    t.parent.should == e
-    e.to_s.should == "<root>test</root>"
-  end
-
-  it "expects escaped text if raw is true" do
-    t = REXML::Text.new("&lt;&amp;&gt;", false, nil, true)
-    t.should == "&lt;&amp;&gt;"
-
-    ->{ REXML::Text.new("<&>", false, nil, true)}.should raise_error(Exception)
-  end
-
-  it "uses raw value of the parent if raw is nil" do
-    e1 = REXML::Element.new("root", nil, { raw: :all})
-    -> {REXML::Text.new("<&>", false, e1)}.should raise_error(Exception)
-
-    e2 = REXML::Element.new("root", nil, { raw: []})
-    e2.raw.should be_false
-    t1 = REXML::Text.new("<&>", false, e2)
-    t1.should == "&lt;&amp;&gt;"
-  end
-
-  it "escapes the values if raw is false" do
-    t = REXML::Text.new("<&>", false, nil, false)
-    t.should == "&lt;&amp;&gt;"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/node_type_spec.rb b/spec/ruby/library/rexml/text/node_type_spec.rb
deleted file mode 100644
index 1c25a74dad..0000000000
--- a/spec/ruby/library/rexml/text/node_type_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#node_type" do
-  it "returns :text" do
-    REXML::Text.new("test").node_type.should == :text
-  end
-end
diff --git a/spec/ruby/library/rexml/text/normalize_spec.rb b/spec/ruby/library/rexml/text/normalize_spec.rb
deleted file mode 100644
index ce3b2b3b5f..0000000000
--- a/spec/ruby/library/rexml/text/normalize_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text.normalize" do
-  it "escapes a string with <, >, &, ' and \" " do
-    REXML::Text.normalize("< > & \" '").should == "&lt; &gt; &amp; &quot; &apos;"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/read_with_substitution_spec.rb b/spec/ruby/library/rexml/text/read_with_substitution_spec.rb
deleted file mode 100644
index 83b42f6d6b..0000000000
--- a/spec/ruby/library/rexml/text/read_with_substitution_spec.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text.read_with_substitution" do
-  it "reads a text and escapes entities" do
-    REXML::Text.read_with_substitution("&lt; &gt; &amp; &quot; &apos;").should == "< > & \" '"
-  end
-
-  it "accepts an regex for invalid expressions and raises an error if text matches" do
-    -> {REXML::Text.read_with_substitution("this is illegal", /illegal/)}.should raise_error(Exception)
-  end
-end
diff --git a/spec/ruby/library/rexml/text/to_s_spec.rb b/spec/ruby/library/rexml/text/to_s_spec.rb
deleted file mode 100644
index 14d7399a60..0000000000
--- a/spec/ruby/library/rexml/text/to_s_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#to_s" do
-  it "returns the string of this Text node" do
-    u = REXML::Text.new("sean russell", false, nil, true)
-    u.to_s.should == "sean russell"
-
-    t = REXML::Text.new("some test text")
-    t.to_s.should == "some test text"
-  end
-
-  it "escapes the text" do
-    t = REXML::Text.new("& < >")
-    t.to_s.should == "&amp; &lt; &gt;"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/unnormalize_spec.rb b/spec/ruby/library/rexml/text/unnormalize_spec.rb
deleted file mode 100644
index 3072809c13..0000000000
--- a/spec/ruby/library/rexml/text/unnormalize_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text.unnormalize" do
-  it "unescapes a string with the values defined in SETUTITSBUS" do
-    REXML::Text.unnormalize("&lt; &gt; &amp; &quot; &apos;").should == "< > & \" '"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/value_spec.rb b/spec/ruby/library/rexml/text/value_spec.rb
deleted file mode 100644
index b0545b3cbd..0000000000
--- a/spec/ruby/library/rexml/text/value_spec.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#value" do
-  it "returns the text value of this node" do
-    REXML::Text.new("test").value.should == "test"
-  end
-
-  it "does not escape entities" do
-    REXML::Text.new("& \"").value.should == "& \""
-  end
-
-  it "follows the respect_whitespace attribute" do
-    REXML::Text.new("test     bar", false).value.should == "test bar"
-    REXML::Text.new("test     bar", true).value.should == "test     bar"
-  end
-
-  it "ignores the raw attribute" do
-    REXML::Text.new("sean russell", false, nil, true).value.should == "sean russell"
-  end
-end
-
-describe "REXML::Text#value=" do
-  before :each do
-    @t = REXML::Text.new("new")
-  end
-
-  it "sets the text of the node" do
-    @t.value = "another text"
-    @t.to_s.should == "another text"
-  end
-
-  it "escapes entities" do
-    @t.value = "<a>"
-    @t.to_s.should == "&lt;a&gt;"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/wrap_spec.rb b/spec/ruby/library/rexml/text/wrap_spec.rb
deleted file mode 100644
index 0b60fd4151..0000000000
--- a/spec/ruby/library/rexml/text/wrap_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#wrap" do
-  before :each do
-    @t = REXML::Text.new("abc def")
-  end
-
-  it "wraps the text at width" do
-    @t.wrap("abc def", 3, false).should == "abc\ndef"
-  end
-
-  it "returns the string if width is greater than the size of the string" do
-    @t.wrap("abc def", 10, false).should == "abc def"
-  end
-
-  it "takes a newline at the beginning option as the third parameter" do
-    @t.wrap("abc def", 3, true).should == "\nabc\ndef"
-  end
-end
diff --git a/spec/ruby/library/rexml/text/write_with_substitution_spec.rb b/spec/ruby/library/rexml/text/write_with_substitution_spec.rb
deleted file mode 100644
index ee79489d86..0000000000
--- a/spec/ruby/library/rexml/text/write_with_substitution_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require 'rexml/document'
-
-describe "REXML::Text#write_with_substitution" do
-  before :each do
-    @t = REXML::Text.new("test")
-    @f = tmp("rexml_spec")
-    @file = File.open(@f, "w+")
-  end
-
-  after :each do
-    @file.close
-    rm_r @f
-  end
-
-  it "writes out the input to a String" do
-    s = ""
-    @t.write_with_substitution(s, "some text")
-    s.should == "some text"
-  end
-
-  it "writes out the input to an IO" do
-    @t.write_with_substitution(@file, "some text")
-    @file.rewind
-    @file.gets.should == "some text"
-  end
-
-  it "escapes characters" do
-    @t.write_with_substitution(@file, "& < >")
-    @file.rewind
-    @file.gets.should == "&amp; &lt; &gt;"
-  end
-end
diff --git a/spec/ruby/library/ripper/lex_spec.rb b/spec/ruby/library/ripper/lex_spec.rb
new file mode 100644
index 0000000000..0255480579
--- /dev/null
+++ b/spec/ruby/library/ripper/lex_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../spec_helper'
+require 'ripper'
+
+describe "Ripper.lex" do
+  it "lexes a simple method declaration" do
+    expected = [
+        [[1, 0], :on_kw, "def", 'FNAME'],
+        [[1, 3], :on_sp, " ", 'FNAME'],
+        [[1, 4], :on_ident, "m", 'ENDFN'],
+        [[1, 5], :on_lparen, "(", 'BEG|LABEL'],
+        [[1, 6], :on_ident, "a", 'ARG'],
+        [[1, 7], :on_rparen, ")", 'ENDFN'],
+        [[1, 8], :on_semicolon, ";", 'BEG'],
+        [[1, 9], :on_kw, "nil", 'END'],
+        [[1, 12], :on_sp, " ", 'END'],
+        [[1, 13], :on_kw, "end", 'END']
+    ]
+    lexed = Ripper.lex("def m(a);nil end")
+    lexed.map { |e|
+      e[0...-1] + [e[-1].to_s]
+    }.should == expected
+  end
+end
diff --git a/spec/ruby/library/ripper/sexp_spec.rb b/spec/ruby/library/ripper/sexp_spec.rb
new file mode 100644
index 0000000000..6c69624c65
--- /dev/null
+++ b/spec/ruby/library/ripper/sexp_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+require 'ripper'
+
+describe "Ripper.sexp" do
+  it "returns an s-expression for a method declaration" do
+    expected = [:program,
+                [[:def,
+                  [:@ident, "hello", [1, 4]],
+                  [:params, nil, nil, nil, nil, nil, nil, nil],
+                  [:bodystmt, [[:@int, "42", [1, 11]]], nil, nil, nil]]]]
+    Ripper.sexp("def hello; 42; end").should == expected
+  end
+end
diff --git a/spec/ruby/library/rubygems/gem/bin_path_spec.rb b/spec/ruby/library/rubygems/gem/bin_path_spec.rb
index ab4ea9397e..0b8c4db08b 100644
--- a/spec/ruby/library/rubygems/gem/bin_path_spec.rb
+++ b/spec/ruby/library/rubygems/gem/bin_path_spec.rb
@@ -11,7 +11,7 @@ describe "Gem.bin_path" do
     ENV['BUNDLE_GEMFILE'] = @bundle_gemfile
   end
 
-  guard_not -> { platform_is :windows } do
+  platform_is_not :windows do
     it "finds executables of default gems, which are the only files shipped for default gems" do
       # For instance, Gem.bin_path("bundler", "bundle") is used by rails new
 
@@ -22,6 +22,7 @@ describe "Gem.bin_path" do
       end
 
       skip "Could not find the default gemspecs" unless Dir.exist?(default_specifications_dir)
+      skip "default_specifications_dir mismatch with GEM_HOME" if ENV["GEM_HOME"] && !default_specifications_dir.start_with?(ENV['GEM_HOME'])
 
       Gem::Specification.each_spec([default_specifications_dir]) do |spec|
         spec.executables.each do |exe|
diff --git a/spec/ruby/library/rubygems/gem/load_path_insert_index_spec.rb b/spec/ruby/library/rubygems/gem/load_path_insert_index_spec.rb
new file mode 100644
index 0000000000..693c72a29e
--- /dev/null
+++ b/spec/ruby/library/rubygems/gem/load_path_insert_index_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../../../spec_helper'
+require 'rubygems'
+
+describe "Gem.load_path_insert_index" do
+  guard -> { RbConfig::TOPDIR } do
+    it "is set for an installed Ruby" do
+      Gem.load_path_insert_index.should.is_a? Integer
+    end
+  end
+end
diff --git a/spec/ruby/library/scanf/io/block_scanf_spec.rb b/spec/ruby/library/scanf/io/block_scanf_spec.rb
deleted file mode 100644
index b9cc1b507e..0000000000
--- a/spec/ruby/library/scanf/io/block_scanf_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require_relative 'shared/block_scanf'
-  require 'scanf'
-
-  describe "IO#block_scanf" do
-    it_behaves_like :scanf_io_block_scanf, :block_scanf
-  end
-end
diff --git a/spec/ruby/library/scanf/io/fixtures/date.txt b/spec/ruby/library/scanf/io/fixtures/date.txt
deleted file mode 100644
index a1bd635c0c..0000000000
--- a/spec/ruby/library/scanf/io/fixtures/date.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-Beethoven  1770
-Bach       1685
-Handel     1685
-
diff --git a/spec/ruby/library/scanf/io/fixtures/helloworld.txt b/spec/ruby/library/scanf/io/fixtures/helloworld.txt
deleted file mode 100644
index 3b18e512db..0000000000
--- a/spec/ruby/library/scanf/io/fixtures/helloworld.txt
+++ /dev/null
@@ -1 +0,0 @@
-hello world
diff --git a/spec/ruby/library/scanf/io/scanf_spec.rb b/spec/ruby/library/scanf/io/scanf_spec.rb
deleted file mode 100644
index 6a1fd66780..0000000000
--- a/spec/ruby/library/scanf/io/scanf_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require_relative 'shared/block_scanf'
-  require 'scanf'
-
-  describe "IO#scanf" do
-    before :each do
-      @hw = File.open(fixture(__FILE__, 'helloworld.txt'), 'r')
-      @data = File.open(fixture(__FILE__, 'date.txt'), 'r')
-    end
-
-    after :each do
-      @hw.close unless @hw.closed?
-      @data.close unless @data.closed?
-    end
-
-    it "returns an array containing the input converted in the specified type" do
-      @hw.scanf("%s%s").should == ["hello", "world"]
-      @data.scanf("%s%d").should == ["Beethoven", 1770]
-    end
-
-    it "returns an array containing the input converted in the specified type with given maximum field width" do
-      @hw.scanf("%2s").should == ["he"]
-      @data.scanf("%2c").should == ["Be"]
-    end
-
-    it "returns an empty array when a wrong specifier is passed" do
-      @hw.scanf("%a").should == []
-      @hw.scanf("%1").should == []
-      @data.scanf("abc").should == []
-    end
-  end
-
-  describe "IO#scanf with block" do
-    it_behaves_like :scanf_io_block_scanf, :scanf
-  end
-end
diff --git a/spec/ruby/library/scanf/io/shared/block_scanf.rb b/spec/ruby/library/scanf/io/shared/block_scanf.rb
deleted file mode 100644
index 2031f4c2b7..0000000000
--- a/spec/ruby/library/scanf/io/shared/block_scanf.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require 'scanf'
-
-describe :scanf_io_block_scanf, shared: true do
-  before :each do
-    @data = File.open(fixture(__FILE__, 'date.txt'), 'r')
-  end
-
-  after :each do
-    @data.close unless @data.closed?
-  end
-
-  it "passes each match to the block as an array" do
-    res = @data.send(@method, "%s%d") { |name, year| "#{name} was born in #{year}." }
-    res.should == ["Beethoven was born in 1770.", "Bach was born in 1685.", "Handel was born in 1685."]
-  end
-
-  it "keeps scanning the input and cycling back to the beginning of the input string" do
-    a = []
-    @data.send(@method, "%s"){|w| a << w}
-    a.should == [["Beethoven"], ["1770"], ["Bach"], ["1685"], ["Handel"], ["1685"]]
-  end
-
-  it "returns an empty array when a wrong specifier is passed" do
-    a = []
-    @data.send(@method, "%z"){|w| a << w}
-    a.empty?.should be_true
-  end
-end
diff --git a/spec/ruby/library/scanf/string/block_scanf_spec.rb b/spec/ruby/library/scanf/string/block_scanf_spec.rb
deleted file mode 100644
index 277e1fa1d7..0000000000
--- a/spec/ruby/library/scanf/string/block_scanf_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require_relative 'shared/block_scanf'
-  require 'scanf'
-
-  describe "String#block_scanf" do
-    it_behaves_like :scanf_string_block_scanf, :block_scanf
-  end
-end
diff --git a/spec/ruby/library/scanf/string/scanf_spec.rb b/spec/ruby/library/scanf/string/scanf_spec.rb
deleted file mode 100644
index c8897db675..0000000000
--- a/spec/ruby/library/scanf/string/scanf_spec.rb
+++ /dev/null
@@ -1,56 +0,0 @@
-require_relative '../../../spec_helper'
-
-ruby_version_is ''...'2.7' do
-  require_relative 'shared/block_scanf'
-  require 'scanf'
-
-  describe "String#scanf" do
-    it "returns an array containing the input converted in the specified type" do
-      "hello world".scanf("%s").should == ["hello"]
-      "hello world".scanf("%s%d").should == ["hello"]
-      "hello world".scanf("%s%c").should == ["hello", " "]
-      "hello world".scanf("%c%s").should == ["h", "ello"]
-      "hello world".scanf("%s%s").should == ["hello", "world"]
-      "hello world".scanf("%c").should == ["h"]
-      "123".scanf("%s").should == ["123"]
-      "123".scanf("%c").should == ["1"]
-      "123".scanf("%d").should == [123]
-      "123".scanf("%u").should == [123]
-      "123".scanf("%o").should == [83]
-      "123".scanf("%x").should == [291]
-      "123".scanf("%i").should == [123]
-      "0123".scanf("%i").should == [83]
-      "123".scanf("%f").should == [123.0]
-      "0X123".scanf("%i").should == [291]
-      "0x123".scanf("%i").should == [291]
-    end
-
-    it "returns an array containing the input converted in the specified type with given maximum field width" do
-      "hello world".scanf("%2s").should == ["he"]
-      "hello world".scanf("%2c").should == ["he"]
-      "123".scanf("%2s").should == ["12"]
-      "123".scanf("%2c").should == ["12"]
-      "123".scanf("%2d").should == [12]
-      "123".scanf("%2u").should == [12]
-      "123".scanf("%2o").should == [10]
-      "123".scanf("%2x").should == [18]
-      "123".scanf("%2i").should == [12]
-      "0123".scanf("%2i").should == [1]
-      "123".scanf("%2f").should == [12.0]
-      "0X123".scanf("%2i").should == [0]
-      "0X123".scanf("%3i").should == [1]
-      "0X123".scanf("%4i").should == [18]
-    end
-
-    it "returns an empty array when a wrong specifier is passed" do
-      "hello world".scanf("%a").should == []
-      "123".scanf("%1").should == []
-      "123".scanf("abc").should == []
-      "123".scanf(:d).should == []
-    end
-  end
-
-  describe "String#scanf with block" do
-    it_behaves_like :scanf_string_block_scanf, :scanf
-  end
-end
diff --git a/spec/ruby/library/scanf/string/shared/block_scanf.rb b/spec/ruby/library/scanf/string/shared/block_scanf.rb
deleted file mode 100644
index 25ab3f442a..0000000000
--- a/spec/ruby/library/scanf/string/shared/block_scanf.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require 'scanf'
-
-describe :scanf_string_block_scanf, shared: true do
-  it "passes each match to the block as an array" do
-    a = []
-    "hello world".send(@method, "%s%s"){|w| a << w}
-    a.should == [["hello", "world"]]
-  end
-
-  it "keeps scanning the input and cycling back to the beginning of the input string" do
-    a = []
-    "hello world".send(@method, "%s"){|w| a << w}
-    a.should == [["hello"], ["world"]]
-
-    string = "123 abc 456 def 789 ghi"
-    s = string.send(@method, "%d%s"){|num,str| [num * 2, str.upcase]}
-    s.should == [[246, "ABC"], [912, "DEF"], [1578, "GHI"]]
-  end
-
-  it "returns an empty array when a wrong specifier is passed" do
-    a = []
-    "hello world".send(@method, "%z"){|w| a << w}
-    a.empty?.should be_true
-  end
-end
diff --git a/spec/ruby/library/securerandom/base64_spec.rb b/spec/ruby/library/securerandom/base64_spec.rb
index 34cd419ce2..49d4b8a029 100644
--- a/spec/ruby/library/securerandom/base64_spec.rb
+++ b/spec/ruby/library/securerandom/base64_spec.rb
@@ -6,13 +6,13 @@ describe "SecureRandom.base64" do
   it "generates a random base64 string out of specified number of random bytes" do
     (16..128).each do |idx|
       base64 = SecureRandom.base64(idx)
-      base64.should be_kind_of(String)
+      base64.should.is_a?(String)
       base64.length.should < 2 * idx
       base64.should =~ /^[A-Za-z0-9\+\/]+={0,2}$/
     end
 
     base64 = SecureRandom.base64(16.5)
-    base64.should be_kind_of(String)
+    base64.should.is_a?(String)
     base64.length.should < 2 * 16
   end
 
@@ -32,19 +32,19 @@ describe "SecureRandom.base64" do
   end
 
   it "generates a random base64 string out of 32 random bytes" do
-    SecureRandom.base64.should be_kind_of(String)
+    SecureRandom.base64.should.is_a?(String)
     SecureRandom.base64.length.should < 32 * 2
   end
 
   it "treats nil argument as default one and generates a random base64 string" do
-    SecureRandom.base64(nil).should be_kind_of(String)
+    SecureRandom.base64(nil).should.is_a?(String)
     SecureRandom.base64(nil).length.should < 32 * 2
   end
 
   it "raises ArgumentError on negative arguments" do
     -> {
       SecureRandom.base64(-1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "tries to convert the passed argument to an Integer using #to_int" do
diff --git a/spec/ruby/library/securerandom/bytes_spec.rb b/spec/ruby/library/securerandom/bytes_spec.rb
new file mode 100644
index 0000000000..a1ab836d16
--- /dev/null
+++ b/spec/ruby/library/securerandom/bytes_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative '../../core/random/shared/bytes'
+
+require 'securerandom'
+
+describe "SecureRandom.bytes" do
+  it_behaves_like :random_bytes, :bytes, SecureRandom
+end
diff --git a/spec/ruby/library/securerandom/hex_spec.rb b/spec/ruby/library/securerandom/hex_spec.rb
index bdb920b217..ec33aca1ee 100644
--- a/spec/ruby/library/securerandom/hex_spec.rb
+++ b/spec/ruby/library/securerandom/hex_spec.rb
@@ -6,13 +6,13 @@ describe "SecureRandom.hex" do
   it "generates a random hex string of length twice the specified argument" do
     (1..64).each do |idx|
       hex = SecureRandom.hex(idx)
-      hex.should be_kind_of(String)
+      hex.should.is_a?(String)
       hex.length.should == 2 * idx
     end
 
     base64 = SecureRandom.hex(5.5)
-    base64.should be_kind_of(String)
-    base64.length.should eql(10)
+    base64.should.is_a?(String)
+    base64.length.should.eql?(10)
   end
 
   it "returns an empty string when argument is 0" do
@@ -31,24 +31,24 @@ describe "SecureRandom.hex" do
   end
 
   it "generates a random hex string of length 32 if no argument is provided" do
-    SecureRandom.hex.should be_kind_of(String)
+    SecureRandom.hex.should.is_a?(String)
     SecureRandom.hex.length.should == 32
   end
 
   it "treats nil argument as default one and generates a random hex string of length 32" do
-    SecureRandom.hex(nil).should be_kind_of(String)
+    SecureRandom.hex(nil).should.is_a?(String)
     SecureRandom.hex(nil).length.should == 32
   end
 
   it "raises ArgumentError on negative arguments" do
     -> {
       SecureRandom.hex(-1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "tries to convert the passed argument to an Integer using #to_int" do
     obj = mock("to_int")
     obj.should_receive(:to_int).and_return(5)
-    SecureRandom.hex(obj).size.should eql(10)
+    SecureRandom.hex(obj).size.should.eql?(10)
   end
 end
diff --git a/spec/ruby/library/securerandom/random_bytes_spec.rb b/spec/ruby/library/securerandom/random_bytes_spec.rb
index 2794174f40..4e30a53163 100644
--- a/spec/ruby/library/securerandom/random_bytes_spec.rb
+++ b/spec/ruby/library/securerandom/random_bytes_spec.rb
@@ -5,28 +5,27 @@ require 'securerandom'
 
 describe "SecureRandom.random_bytes" do
   it_behaves_like :random_bytes, :random_bytes, SecureRandom
-  it_behaves_like :random_bytes, :bytes, SecureRandom
 
   it "generates a random binary string of length 16 if no argument is provided" do
     bytes = SecureRandom.random_bytes
-    bytes.should be_kind_of(String)
+    bytes.should.is_a?(String)
     bytes.length.should == 16
   end
 
   it "generates a random binary string of length 16 if argument is nil" do
     bytes = SecureRandom.random_bytes(nil)
-    bytes.should be_kind_of(String)
+    bytes.should.is_a?(String)
     bytes.length.should == 16
   end
 
   it "generates a random binary string of specified length" do
     (1..64).each do |idx|
       bytes = SecureRandom.random_bytes(idx)
-      bytes.should be_kind_of(String)
+      bytes.should.is_a?(String)
       bytes.length.should == idx
     end
 
-    SecureRandom.random_bytes(2.2).length.should eql(2)
+    SecureRandom.random_bytes(2.2).length.should.eql?(2)
   end
 
   it "generates different binary strings with subsequent invocations" do
@@ -43,12 +42,12 @@ describe "SecureRandom.random_bytes" do
   it "raises ArgumentError on negative arguments" do
     -> {
       SecureRandom.random_bytes(-1)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it "tries to convert the passed argument to an Integer using #to_int" do
     obj = mock("to_int")
     obj.should_receive(:to_int).and_return(5)
-    SecureRandom.random_bytes(obj).size.should eql(5)
+    SecureRandom.random_bytes(obj).size.should.eql?(5)
   end
 end
diff --git a/spec/ruby/library/securerandom/random_number_spec.rb b/spec/ruby/library/securerandom/random_number_spec.rb
index 3e1812c6e8..97cd66f7bc 100644
--- a/spec/ruby/library/securerandom/random_number_spec.rb
+++ b/spec/ruby/library/securerandom/random_number_spec.rb
@@ -10,9 +10,9 @@ describe "SecureRandom.random_number" do
   it "generates a random positive number smaller then the positive integer argument" do
     (1..64).each do |idx|
       num = SecureRandom.random_number(idx)
-      num.should be_kind_of(Fixnum)
-      (0 <= num).should == true
-      (num < idx).should == true
+      num.should.is_a?(Integer)
+      0.should <= num
+      num.should < idx
     end
   end
 
@@ -20,27 +20,27 @@ describe "SecureRandom.random_number" do
     max = 12345678901234567890
     11.times do
       num = SecureRandom.random_number max
-      num.should be_kind_of(Integer)
-      (0 <= num).should == true
-      (num < max).should == true
+      num.should.is_a?(Integer)
+      0.should <= num
+      num.should < max
     end
   end
 
   it "generates a random float number between 0.0 and 1.0 if no argument provided" do
     64.times do
       num = SecureRandom.random_number
-      num.should be_kind_of(Float)
-      (0.0 <= num).should == true
-      (num < 1.0).should == true
+      num.should.is_a?(Float)
+      0.0.should <= num
+      num.should < 1.0
     end
   end
 
   it "generates a random value in given (integer) range limits" do
     64.times do
       num = SecureRandom.random_number 11...13
-      num.should be_kind_of(Integer)
-      (11 <= num).should == true
-      (num < 13).should == true
+      num.should.is_a?(Integer)
+      11.should <= num
+      num.should < 13
     end
   end
 
@@ -49,33 +49,33 @@ describe "SecureRandom.random_number" do
     upper = 12345678901234567890 + 5
     32.times do
       num = SecureRandom.random_number lower..upper
-      num.should be_kind_of(Integer)
-      (lower <= num).should == true
-      (num <= upper).should == true
+      num.should.is_a?(Integer)
+      lower.should <= num
+      num.should <= upper
     end
   end
 
   it "generates a random value in given (float) range limits" do
     64.times do
       num = SecureRandom.random_number 0.6..0.9
-      num.should be_kind_of(Float)
-      (0.6 <= num).should == true
-      (num <= 0.9).should == true
+      num.should.is_a?(Float)
+      0.6.should <= num
+      num.should <= 0.9
     end
   end
 
   it "generates a random float number between 0.0 and 1.0 if argument is negative" do
     num = SecureRandom.random_number(-10)
-    num.should be_kind_of(Float)
-    (0.0 <= num).should == true
-    (num < 1.0).should == true
+    num.should.is_a?(Float)
+    0.0.should <= num
+    num.should < 1.0
   end
 
   it "generates a random float number between 0.0 and 1.0 if argument is negative float" do
     num = SecureRandom.random_number(-11.1)
-    num.should be_kind_of(Float)
-    (0.0 <= num).should == true
-    (num < 1.0).should == true
+    num.should.is_a?(Float)
+    0.0.should <= num
+    num.should < 1.0
   end
 
   it "generates different float numbers with subsequent invocations" do
@@ -84,7 +84,7 @@ describe "SecureRandom.random_number" do
     256.times do
       val = SecureRandom.random_number
       # make sure the random values are not repeating
-      values.include?(val).should == false
+      values.should_not.include?(val)
       values << val
     end
   end
@@ -92,6 +92,6 @@ describe "SecureRandom.random_number" do
   it "raises ArgumentError if the argument is non-numeric" do
     -> {
       SecureRandom.random_number(Object.new)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/set/add_spec.rb b/spec/ruby/library/set/add_spec.rb
deleted file mode 100644
index 68356cc111..0000000000
--- a/spec/ruby/library/set/add_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/add'
-
-describe "Set#add" do
-  it_behaves_like :set_add, :add
-end
-
-describe "Set#add?" do
-  before :each do
-    @set = Set.new
-  end
-
-  it "adds the passed Object to self" do
-    @set.add?("cat")
-    @set.should include("cat")
-  end
-
-  it "returns self when the Object has not yet been added to self" do
-    @set.add?("cat").should equal(@set)
-  end
-
-  it "returns nil when the Object has already been added to self" do
-    @set.add?("cat")
-    @set.add?("cat").should be_nil
-  end
-end
diff --git a/spec/ruby/library/set/append_spec.rb b/spec/ruby/library/set/append_spec.rb
deleted file mode 100644
index 8b3498b779..0000000000
--- a/spec/ruby/library/set/append_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/add'
-
-describe "Set#<<" do
-  it_behaves_like :set_add, :<<
-end
diff --git a/spec/ruby/library/set/case_compare_spec.rb b/spec/ruby/library/set/case_compare_spec.rb
deleted file mode 100644
index 193006dbda..0000000000
--- a/spec/ruby/library/set/case_compare_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-ruby_version_is "2.5" do
-  describe "Set#===" do
-    it_behaves_like :set_include, :===
-
-    it "is an alias for include?" do
-      set = Set.new
-      set.method(:===).should == set.method(:include?)
-    end
-  end
-end
diff --git a/spec/ruby/library/set/case_equality_spec.rb b/spec/ruby/library/set/case_equality_spec.rb
deleted file mode 100644
index 875630612e..0000000000
--- a/spec/ruby/library/set/case_equality_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-ruby_version_is "2.5" do
-  describe "Set#===" do
-    it_behaves_like :set_include, :===
-  end
-end
diff --git a/spec/ruby/library/set/classify_spec.rb b/spec/ruby/library/set/classify_spec.rb
deleted file mode 100644
index ec600c91d6..0000000000
--- a/spec/ruby/library/set/classify_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#classify" do
-  before :each do
-    @set = Set["one", "two", "three", "four"]
-  end
-
-  it "yields each Object in self" do
-    res = []
-    @set.classify { |x| res << x }
-    res.sort.should == ["one", "two", "three", "four"].sort
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.classify
-    enum.should be_an_instance_of(Enumerator)
-
-    classified = enum.each { |x| x.length }
-    classified.should == { 3 => Set["one", "two"], 4 => Set["four"], 5 => Set["three"] }
-  end
-
-  it "classifies the Objects in self based on the block's return value" do
-    classified = @set.classify { |x| x.length }
-    classified.should == { 3 => Set["one", "two"], 4 => Set["four"], 5 => Set["three"] }
-  end
-end
diff --git a/spec/ruby/library/set/clear_spec.rb b/spec/ruby/library/set/clear_spec.rb
deleted file mode 100644
index 2b1c9c5b5a..0000000000
--- a/spec/ruby/library/set/clear_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#clear" do
-  before :each do
-    @set = Set["one", "two", "three", "four"]
-  end
-
-  it "removes all elements from self" do
-    @set.clear
-    @set.should be_empty
-  end
-
-  it "returns self" do
-    @set.clear.should equal(@set)
-  end
-end
diff --git a/spec/ruby/library/set/collect_spec.rb b/spec/ruby/library/set/collect_spec.rb
deleted file mode 100644
index f8813a9331..0000000000
--- a/spec/ruby/library/set/collect_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/collect'
-
-describe "Set#collect!" do
-  it_behaves_like :set_collect_bang, :collect!
-end
diff --git a/spec/ruby/library/set/compare_by_identity_spec.rb b/spec/ruby/library/set/compare_by_identity_spec.rb
deleted file mode 100644
index a6ad794ad3..0000000000
--- a/spec/ruby/library/set/compare_by_identity_spec.rb
+++ /dev/null
@@ -1,143 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#compare_by_identity" do
-  it "compares its members by identity" do
-    a = "a"
-    b1 = "b"
-    b2 = "b"
-
-    set = Set.new
-    set.compare_by_identity
-    set.merge([a, a, b1, b2])
-    set.to_a.sort.should == [a, b1, b2].sort
-  end
-
-  it "causes future comparisons on the receiver to be made by identity" do
-    elt = [1]
-    set = Set.new
-    set << elt
-    set.member?(elt.dup).should be_true
-    set.compare_by_identity
-    set.member?(elt.dup).should be_false
-  end
-
-  it "rehashes internally so that old members can be looked up" do
-    set = Set.new
-    (1..10).each { |k| set << k }
-    o = Object.new
-    def o.hash; 123; end
-    set << o
-    set.compare_by_identity
-    set.member?(o).should be_true
-  end
-
-  it "returns self" do
-    set = Set.new
-    result = set.compare_by_identity
-    result.should equal(set)
-  end
-
-  it "is idempotent and has no effect on an already compare_by_identity set" do
-    set = Set.new.compare_by_identity
-    set << :foo
-    set.compare_by_identity.should equal(set)
-    set.compare_by_identity?.should == true
-    set.to_a.should == [:foo]
-  end
-
-  it "uses the semantics of BasicObject#equal? to determine members identity" do
-    :a.equal?(:a).should == true
-    Set.new.compare_by_identity.merge([:a, :a]).to_a.should == [:a]
-
-    ary1 = [1]
-    ary2 = [1]
-    ary1.equal?(ary2).should == false
-    Set.new.compare_by_identity.merge([ary1, ary2]).to_a.sort.should == [ary1, ary2].sort
-  end
-
-  it "uses #equal? semantics, but doesn't actually call #equal? to determine identity" do
-    set = Set.new.compare_by_identity
-    obj = mock("equal")
-    obj.should_not_receive(:equal?)
-    set << :foo
-    set << obj
-    set.to_a.should == [:foo, obj]
-  end
-
-  it "does not call #hash on members" do
-    elt = mock("element")
-    elt.should_not_receive(:hash)
-    set = Set.new.compare_by_identity
-    set << elt
-    set.member?(elt).should be_true
-  end
-
-  it "regards #dup'd objects as having different identities" do
-    a1 = "a"
-    a2 = a1.dup
-
-    set = Set.new.compare_by_identity
-    set.merge([a1, a2])
-    set.to_a.sort.should == [a1, a2].sort
-  end
-
-  it "regards #clone'd objects as having different identities" do
-    a1 = "a"
-    a2 = a1.clone
-
-    set = Set.new.compare_by_identity
-    set.merge([a1, a2])
-    set.to_a.sort.should == [a1, a2].sort
-  end
-
-  it "raises a #{frozen_error_class} on frozen sets" do
-    set = Set.new.freeze
-    -> {
-      set.compare_by_identity
-    }.should raise_error(frozen_error_class, /frozen Hash/)
-  end
-
-  it "persists over #dups" do
-    set = Set.new.compare_by_identity
-    set << :a
-    set_dup = set.dup
-    set_dup.should == set
-    set_dup << :a
-    set_dup.to_a.should == [:a]
-  end
-
-  it "persists over #clones" do
-    set = Set.new.compare_by_identity
-    set << :a
-    set_clone = set.clone
-    set_clone.should == set
-    set_clone << :a
-    set_clone.to_a.should == [:a]
-  end
-
-  it "is not equal to set what does not compare by identity" do
-    Set.new([1, 2]).should == Set.new([1, 2])
-    Set.new([1, 2]).should_not == Set.new([1, 2]).compare_by_identity
-  end
-end
-
-describe "Set#compare_by_identity?" do
-  it "returns false by default" do
-    Set.new.compare_by_identity?.should == false
-  end
-
-  it "returns true once #compare_by_identity has been invoked on self" do
-    set = Set.new
-    set.compare_by_identity
-    set.compare_by_identity?.should == true
-  end
-
-  it "returns true when called multiple times on the same set" do
-    set = Set.new
-    set.compare_by_identity
-    set.compare_by_identity?.should == true
-    set.compare_by_identity?.should == true
-    set.compare_by_identity?.should == true
-  end
-end
diff --git a/spec/ruby/library/set/constructor_spec.rb b/spec/ruby/library/set/constructor_spec.rb
deleted file mode 100644
index bb84861514..0000000000
--- a/spec/ruby/library/set/constructor_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set[]" do
-  it "returns a new Set populated with the passed Objects" do
-    set = Set[1, 2, 3]
-
-    set.instance_of?(Set).should be_true
-    set.size.should eql(3)
-
-    set.should include(1)
-    set.should include(2)
-    set.should include(3)
-  end
-end
diff --git a/spec/ruby/library/set/delete_if_spec.rb b/spec/ruby/library/set/delete_if_spec.rb
deleted file mode 100644
index 33caeeaab7..0000000000
--- a/spec/ruby/library/set/delete_if_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#delete_if" do
-  before :each do
-    @set = Set["one", "two", "three"]
-  end
-
-  it "yields every element of self" do
-    ret = []
-    @set.delete_if { |x| ret << x }
-    ret.sort.should == ["one", "two", "three"].sort
-  end
-
-  it "deletes every element from self for which the passed block returns true" do
-    @set.delete_if { |x| x.size == 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self" do
-    @set.delete_if { |x| x }.should equal(@set)
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.delete_if
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size == 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/delete_spec.rb b/spec/ruby/library/set/delete_spec.rb
deleted file mode 100644
index b12524384a..0000000000
--- a/spec/ruby/library/set/delete_spec.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#delete" do
-  before :each do
-    @set = Set["a", "b", "c"]
-  end
-
-  it "deletes the passed Object from self" do
-    @set.delete("a")
-    @set.should_not include("a")
-  end
-
-  it "returns self" do
-    @set.delete("a").should equal(@set)
-    @set.delete("x").should equal(@set)
-  end
-end
-
-describe "Set#delete?" do
-  before :each do
-    @set = Set["a", "b", "c"]
-  end
-
-  it "deletes the passed Object from self" do
-    @set.delete?("a")
-    @set.should_not include("a")
-  end
-
-  it "returns self when the passed Object is in self" do
-    @set.delete?("a").should equal(@set)
-  end
-
-  it "returns nil when the passed Object is not in self" do
-    @set.delete?("x").should be_nil
-  end
-end
diff --git a/spec/ruby/library/set/difference_spec.rb b/spec/ruby/library/set/difference_spec.rb
deleted file mode 100644
index 422f2ed3c7..0000000000
--- a/spec/ruby/library/set/difference_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/difference'
-
-describe "Set#difference" do
-  it_behaves_like :set_difference, :difference
-end
diff --git a/spec/ruby/library/set/disjoint_spec.rb b/spec/ruby/library/set/disjoint_spec.rb
deleted file mode 100644
index ea3b141455..0000000000
--- a/spec/ruby/library/set/disjoint_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#disjoint?" do
-  it "returns false when two Sets have at least one element in common" do
-    Set[1, 2].disjoint?(Set[2, 3]).should == false
-  end
-
-  it "returns true when two Sets have no element in common" do
-    Set[1, 2].disjoint?(Set[3, 4]).should == true
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns false when a Set has at least one element in common with a Set-like object" do
-      Set[1, 2].disjoint?(SetSpecs::SetLike.new([2, 3])).should be_false
-    end
-
-    it "returns true when a Set has no element in common with a Set-like object" do
-      Set[1, 2].disjoint?(SetSpecs::SetLike.new([3, 4])).should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/set/divide_spec.rb b/spec/ruby/library/set/divide_spec.rb
deleted file mode 100644
index fdd8cd9622..0000000000
--- a/spec/ruby/library/set/divide_spec.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#divide" do
-  it "divides self into a set of subsets based on the blocks return values" do
-    set = Set["one", "two", "three", "four", "five"].divide { |x| x.length }
-    set.map { |x| x.to_a.sort }.sort.should == [["five", "four"], ["one", "two"], ["three"]]
-  end
-
-  it "yields each Object to the block" do
-    ret = []
-    Set["one", "two", "three", "four", "five"].divide { |x| ret << x }
-    ret.sort.should == ["five", "four", "one", "three", "two"]
-  end
-
-  # BUG: Does not raise a LocalJumpError, but a NoMethodError
-  #
-  # it "raises a LocalJumpError when not passed a block" do
-  #   lambda { Set[1].divide }.should raise_error(LocalJumpError)
-  # end
-end
-
-describe "Set#divide when passed a block with an arity of 2" do
-  it "divides self into a set of subsets based on the blocks return values" do
-    set = Set[1, 3, 4, 6, 9, 10, 11].divide { |x, y| (x - y).abs == 1 }
-    set.map{ |x| x.to_a.sort }.sort.should == [[1], [3, 4], [6], [9, 10, 11]]
-  end
-
-  it "yields each two Object to the block" do
-    ret = []
-    Set[1, 2].divide { |x, y| ret << [x, y] }
-    ret.sort.should == [[1, 1], [1, 2], [2, 1], [2, 2]]
-  end
-end
diff --git a/spec/ruby/library/set/each_spec.rb b/spec/ruby/library/set/each_spec.rb
deleted file mode 100644
index 9bb5ead03a..0000000000
--- a/spec/ruby/library/set/each_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#each" do
-  before :each do
-    @set = Set[1, 2, 3]
-  end
-
-  it "yields each Object in self" do
-    ret = []
-    @set.each { |x| ret << x }
-    ret.sort.should == [1, 2, 3]
-  end
-
-  it "returns self" do
-    @set.each { |x| x }.should equal(@set)
-  end
-
-  it "returns an Enumerator when not passed a block" do
-    enum = @set.each
-
-    ret = []
-    enum.each { |x| ret << x }
-    ret.sort.should == [1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/empty_spec.rb b/spec/ruby/library/set/empty_spec.rb
deleted file mode 100644
index 1789a664c7..0000000000
--- a/spec/ruby/library/set/empty_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#empty?" do
-  it "returns true if self is empty" do
-    Set[].empty?.should be_true
-    Set[1].empty?.should be_false
-    Set[1,2,3].empty?.should be_false
-  end
-end
diff --git a/spec/ruby/library/set/enumerable/to_set_spec.rb b/spec/ruby/library/set/enumerable/to_set_spec.rb
deleted file mode 100644
index 0f5504fef2..0000000000
--- a/spec/ruby/library/set/enumerable/to_set_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "Enumerable#to_set" do
-  it "returns a new Set created from self" do
-    [1, 2, 3].to_set.should == Set[1, 2, 3]
-    {a: 1, b: 2}.to_set.should == Set[[:b, 2], [:a, 1]]
-  end
-
-  it "allows passing an alternate class for Set" do
-    sorted_set = [1, 2, 3].to_set(SortedSet)
-    sorted_set.should == SortedSet[1, 2, 3]
-    sorted_set.instance_of?(SortedSet).should == true
-  end
-
-  it "passes down passed blocks" do
-    [1, 2, 3].to_set { |x| x * x }.should == Set[1, 4, 9]
-  end
-end
diff --git a/spec/ruby/library/set/eql_spec.rb b/spec/ruby/library/set/eql_spec.rb
deleted file mode 100644
index dd8e633775..0000000000
--- a/spec/ruby/library/set/eql_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#eql?" do
-  it "returns true when the passed argument is a Set and contains the same elements" do
-    Set[].should eql(Set[])
-    Set[1, 2, 3].should eql(Set[1, 2, 3])
-    Set[1, 2, 3].should eql(Set[3, 2, 1])
-    Set["a", :b, ?c].should eql(Set[?c, :b, "a"])
-
-    Set[1, 2, 3].should_not eql(Set[1.0, 2, 3])
-    Set[1, 2, 3].should_not eql(Set[2, 3])
-    Set[1, 2, 3].should_not eql(Set[])
-  end
-end
diff --git a/spec/ruby/library/set/equal_value_spec.rb b/spec/ruby/library/set/equal_value_spec.rb
deleted file mode 100644
index f5b5f790c0..0000000000
--- a/spec/ruby/library/set/equal_value_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#==" do
-  it "returns true when the passed Object is a Set and self and the Object contain the same elements" do
-    Set[].should == Set[]
-    Set[1, 2, 3].should == Set[1, 2, 3]
-    Set["1", "2", "3"].should == Set["1", "2", "3"]
-
-    Set[1, 2, 3].should_not == Set[1.0, 2, 3]
-    Set[1, 2, 3].should_not == [1, 2, 3]
-  end
-
-  it "does not depend on the order of the elements" do
-    Set[1, 2, 3].should == Set[3, 2, 1]
-    Set[:a, "b", ?c].should == Set[?c, "b", :a]
-  end
-
-  it "does not depend on the order of nested Sets" do
-    Set[Set[1], Set[2], Set[3]].should == Set[Set[3], Set[2], Set[1]]
-
-    set1 = Set[Set["a", "b"], Set["c", "d"], Set["e", "f"]]
-    set2 = Set[Set["c", "d"], Set["a", "b"], Set["e", "f"]]
-    set1.should == set2
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true when a Set and a Set-like object contain the same elements" do
-      Set[1, 2, 3].should == SetSpecs::SetLike.new([1, 2, 3])
-    end
-  end
-end
diff --git a/spec/ruby/library/set/exclusion_spec.rb b/spec/ruby/library/set/exclusion_spec.rb
deleted file mode 100644
index 5bc4b5a2bf..0000000000
--- a/spec/ruby/library/set/exclusion_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#^" do
-  before :each do
-    @set = Set[1, 2, 3, 4]
-  end
-
-  it "returns a new Set containing elements that are not in both self and the passed Enumerable" do
-    (@set ^ Set[3, 4, 5]).should == Set[1, 2, 5]
-    (@set ^ [3, 4, 5]).should == Set[1, 2, 5]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set ^ 3 }.should raise_error(ArgumentError)
-    -> { @set ^ Object.new }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/filter_spec.rb b/spec/ruby/library/set/filter_spec.rb
deleted file mode 100644
index a4dfe70d52..0000000000
--- a/spec/ruby/library/set/filter_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/select'
-
-ruby_version_is "2.6" do
-  describe "Set#filter!" do
-    it_behaves_like :set_select_bang, :filter!
-  end
-end
diff --git a/spec/ruby/library/set/fixtures/set_like.rb b/spec/ruby/library/set/fixtures/set_like.rb
deleted file mode 100644
index 46f61a451e..0000000000
--- a/spec/ruby/library/set/fixtures/set_like.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require 'set'
-
-module SetSpecs
-  # This class is used to test the interaction of "Set-like" objects with real Sets
-  #
-  # These "Set-like" objects reply to is_a?(Set) with true and thus real Set objects are able to transparently
-  # interoperate with them in a duck-typing manner.
-  class SetLike
-    include Enumerable
-
-    def is_a?(klass)
-      super || klass == ::Set
-    end
-
-    def initialize(entries)
-      @entries = entries
-    end
-
-    def each(&block)
-      @entries.each(&block)
-    end
-
-    def inspect
-      "#<#{self.class}: {#{map(&:inspect).join(", ")}}>"
-    end
-
-    def size
-      @entries.size
-    end
-  end
-end
diff --git a/spec/ruby/library/set/flatten_merge_spec.rb b/spec/ruby/library/set/flatten_merge_spec.rb
deleted file mode 100644
index f2c99a9481..0000000000
--- a/spec/ruby/library/set/flatten_merge_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#flatten_merge" do
-  it "is protected" do
-    Set.should have_protected_instance_method("flatten_merge")
-  end
-
-  it "flattens the passed Set and merges it into self" do
-    set1 = Set[1, 2]
-    set2 = Set[3, 4, Set[5, 6]]
-
-    set1.send(:flatten_merge, set2).should == Set[1, 2, 3, 4, 5, 6]
-  end
-
-  it "raises an ArgumentError when trying to flatten a recursive Set" do
-    set1 = Set[1, 2, 3]
-    set2 = Set[5, 6, 7]
-    set2 << set2
-
-    -> { set1.send(:flatten_merge, set2) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/flatten_spec.rb b/spec/ruby/library/set/flatten_spec.rb
deleted file mode 100644
index 4ac83ea825..0000000000
--- a/spec/ruby/library/set/flatten_spec.rb
+++ /dev/null
@@ -1,53 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#flatten" do
-  it "returns a copy of self with each included Set flattened" do
-    set = Set[1, 2, Set[3, 4, Set[5, 6, Set[7, 8]]], 9, 10]
-    flattened_set = set.flatten
-
-    flattened_set.should_not equal(set)
-    flattened_set.should == Set[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-  end
-
-  it "raises an ArgumentError when self is recursive" do
-    (set = Set[]) << set
-    -> { set.flatten }.should raise_error(ArgumentError)
-  end
-
-  context "when Set contains a Set-like object" do
-    it "returns a copy of self with each included Set-like object flattened" do
-      Set[SetSpecs::SetLike.new([1])].flatten.should == Set[1]
-    end
-  end
-end
-
-describe "Set#flatten!" do
-  it "flattens self" do
-    set = Set[1, 2, Set[3, 4, Set[5, 6, Set[7, 8]]], 9, 10]
-    set.flatten!
-    set.should == Set[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-  end
-
-  it "returns self when self was modified" do
-    set = Set[1, 2, Set[3, 4]]
-    set.flatten!.should equal(set)
-  end
-
-  it "returns nil when self was not modified" do
-    set = Set[1, 2, 3, 4]
-    set.flatten!.should be_nil
-  end
-
-  it "raises an ArgumentError when self is recursive" do
-    (set = Set[]) << set
-    -> { set.flatten! }.should raise_error(ArgumentError)
-  end
-
-  context "when Set contains a Set-like object" do
-    it "flattens self, including Set-like objects" do
-      Set[SetSpecs::SetLike.new([1])].flatten!.should == Set[1]
-    end
-  end
-end
diff --git a/spec/ruby/library/set/hash_spec.rb b/spec/ruby/library/set/hash_spec.rb
deleted file mode 100644
index 47c43c05f1..0000000000
--- a/spec/ruby/library/set/hash_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#hash" do
-  it "is static" do
-    Set[].hash.should == Set[].hash
-    Set[1, 2, 3].hash.should == Set[1, 2, 3].hash
-    Set[:a, "b", ?c].hash.should == Set[?c, "b", :a].hash
-
-    Set[].hash.should_not == Set[1, 2, 3].hash
-    Set[1, 2, 3].hash.should_not == Set[:a, "b", ?c].hash
-  end
-end
diff --git a/spec/ruby/library/set/include_spec.rb b/spec/ruby/library/set/include_spec.rb
deleted file mode 100644
index 68532d9a04..0000000000
--- a/spec/ruby/library/set/include_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-describe "Set#include?" do
-  it_behaves_like :set_include, :include?
-end
diff --git a/spec/ruby/library/set/initialize_spec.rb b/spec/ruby/library/set/initialize_spec.rb
deleted file mode 100644
index 887cae45fc..0000000000
--- a/spec/ruby/library/set/initialize_spec.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#initialize" do
-  it "is private" do
-    Set.should have_private_instance_method(:initialize)
-  end
-
-  it "adds all elements of the passed Enumerable to self" do
-    s = Set.new([1, 2, 3])
-    s.size.should eql(3)
-    s.should include(1)
-    s.should include(2)
-    s.should include(3)
-  end
-
-  it "should initialize with empty array and set" do
-    s = Set.new([])
-    s.size.should eql(0)
-
-    s = Set.new({})
-    s.size.should eql(0)
-  end
-
-  it "preprocesses all elements by a passed block before adding to self" do
-    s = Set.new([1, 2, 3]) { |x| x * x }
-    s.size.should eql(3)
-    s.should include(1)
-    s.should include(4)
-    s.should include(9)
-  end
-
-  it "should initialize with empty array and block" do
-    s = Set.new([]) { |x| x * x }
-    s.size.should eql(0)
-  end
-
-  it "should initialize with empty set and block" do
-    s = Set.new(Set.new) { |x| x * x }
-    s.size.should eql(0)
-  end
-
-  it "should initialize with just block" do
-    s = Set.new { |x| x * x }
-    s.size.should eql(0)
-    s.should eql(Set.new)
-  end
-end
diff --git a/spec/ruby/library/set/inspect_spec.rb b/spec/ruby/library/set/inspect_spec.rb
deleted file mode 100644
index 4060c63b95..0000000000
--- a/spec/ruby/library/set/inspect_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/inspect'
-require 'set'
-
-describe "Set#inspect" do
-  it_behaves_like :set_inspect, :inspect
-end
diff --git a/spec/ruby/library/set/intersect_spec.rb b/spec/ruby/library/set/intersect_spec.rb
deleted file mode 100644
index e60f06db94..0000000000
--- a/spec/ruby/library/set/intersect_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#intersect?" do
-  it "returns true when two Sets have at least one element in common" do
-    Set[1, 2].intersect?(Set[2, 3]).should == true
-  end
-
-  it "returns false when two Sets have no element in common" do
-    Set[1, 2].intersect?(Set[3, 4]).should == false
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true when a Set has at least one element in common with a Set-like object" do
-      Set[1, 2].intersect?(SetSpecs::SetLike.new([2, 3])).should be_true
-    end
-
-    it "returns false when a Set has no element in common with a Set-like object" do
-      Set[1, 2].intersect?(SetSpecs::SetLike.new([3, 4])).should be_false
-    end
-  end
-end
diff --git a/spec/ruby/library/set/intersection_spec.rb b/spec/ruby/library/set/intersection_spec.rb
deleted file mode 100644
index 792c2d8f07..0000000000
--- a/spec/ruby/library/set/intersection_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/intersection'
-require 'set'
-
-describe "Set#intersection" do
-  it_behaves_like :set_intersection, :intersection
-end
-
-describe "Set#&" do
-  it_behaves_like :set_intersection, :&
-end
diff --git a/spec/ruby/library/set/keep_if_spec.rb b/spec/ruby/library/set/keep_if_spec.rb
deleted file mode 100644
index 7edc80769f..0000000000
--- a/spec/ruby/library/set/keep_if_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#keep_if" do
-  before :each do
-    @set = Set["one", "two", "three"]
-  end
-
-  it "yields every element of self" do
-    ret = []
-    @set.keep_if { |x| ret << x }
-    ret.sort.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.keep_if { |x| x.size != 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self" do
-    @set.keep_if {}.should equal(@set)
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.keep_if
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/length_spec.rb b/spec/ruby/library/set/length_spec.rb
deleted file mode 100644
index fef63d25a7..0000000000
--- a/spec/ruby/library/set/length_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/length'
-require 'set'
-
-describe "Set#length" do
-  it_behaves_like :set_length, :length
-end
diff --git a/spec/ruby/library/set/map_spec.rb b/spec/ruby/library/set/map_spec.rb
deleted file mode 100644
index e60e98b179..0000000000
--- a/spec/ruby/library/set/map_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/collect'
-
-describe "Set#map!" do
-  it_behaves_like :set_collect_bang, :map!
-end
diff --git a/spec/ruby/library/set/member_spec.rb b/spec/ruby/library/set/member_spec.rb
deleted file mode 100644
index 5b56a38ab9..0000000000
--- a/spec/ruby/library/set/member_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-describe "Set#member?" do
-  it_behaves_like :set_include, :member?
-end
diff --git a/spec/ruby/library/set/merge_spec.rb b/spec/ruby/library/set/merge_spec.rb
deleted file mode 100644
index a8e3ffc870..0000000000
--- a/spec/ruby/library/set/merge_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#merge" do
-  it "adds the elements of the passed Enumerable to self" do
-    Set[:a, :b].merge(Set[:b, :c, :d]).should == Set[:a, :b, :c, :d]
-    Set[1, 2].merge([3, 4]).should == Set[1, 2, 3, 4]
-  end
-
-  it "returns self" do
-    set = Set[1, 2]
-    set.merge([3, 4]).should equal(set)
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { Set[1, 2].merge(1) }.should raise_error(ArgumentError)
-    -> { Set[1, 2].merge(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/minus_spec.rb b/spec/ruby/library/set/minus_spec.rb
deleted file mode 100644
index 3fe0b6a2cc..0000000000
--- a/spec/ruby/library/set/minus_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-require_relative 'shared/difference'
-
-describe "Set#-" do
-  it_behaves_like :set_difference, :-
-end
diff --git a/spec/ruby/library/set/plus_spec.rb b/spec/ruby/library/set/plus_spec.rb
deleted file mode 100644
index 3e70d3269d..0000000000
--- a/spec/ruby/library/set/plus_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/union'
-require 'set'
-
-describe "Set#+" do
-  it_behaves_like :set_union, :+
-end
diff --git a/spec/ruby/library/set/pretty_print_cycle_spec.rb b/spec/ruby/library/set/pretty_print_cycle_spec.rb
deleted file mode 100644
index 4f440353e5..0000000000
--- a/spec/ruby/library/set/pretty_print_cycle_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#pretty_print_cycle" do
-  it "passes the 'pretty print' representation of a self-referencing Set to the pretty print writer" do
-    pp = mock("PrettyPrint")
-    pp.should_receive(:text).with("#<Set: {...}>")
-    Set[1, 2, 3].pretty_print_cycle(pp)
-  end
-end
diff --git a/spec/ruby/library/set/pretty_print_spec.rb b/spec/ruby/library/set/pretty_print_spec.rb
deleted file mode 100644
index f2392e6968..0000000000
--- a/spec/ruby/library/set/pretty_print_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#pretty_print" do
-  it "passes the 'pretty print' representation of self to the pretty print writer" do
-    pp = mock("PrettyPrint")
-    set = Set[1, 2, 3]
-
-    pp.should_receive(:text).with("#<Set: {")
-    pp.should_receive(:text).with("}>")
-
-    pp.should_receive(:nest).with(1).and_yield
-    pp.should_receive(:seplist).with(set)
-
-    set.pretty_print(pp)
-  end
-end
diff --git a/spec/ruby/library/set/proper_subset_spec.rb b/spec/ruby/library/set/proper_subset_spec.rb
deleted file mode 100644
index 1f496a6199..0000000000
--- a/spec/ruby/library/set/proper_subset_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#proper_subset?" do
-  before :each do
-    @set = Set[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a Set that self is a proper subset of" do
-    Set[].proper_subset?(@set).should be_true
-    Set[].proper_subset?(Set[1, 2, 3]).should be_true
-    Set[].proper_subset?(Set["a", :b, ?c]).should be_true
-
-    Set[1, 2, 3].proper_subset?(@set).should be_true
-    Set[1, 3].proper_subset?(@set).should be_true
-    Set[1, 2].proper_subset?(@set).should be_true
-    Set[1].proper_subset?(@set).should be_true
-
-    Set[5].proper_subset?(@set).should be_false
-    Set[1, 5].proper_subset?(@set).should be_false
-    Set[nil].proper_subset?(@set).should be_false
-    Set["test"].proper_subset?(@set).should be_false
-
-    @set.proper_subset?(@set).should be_false
-    Set[].proper_subset?(Set[]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-Set" do
-    -> { Set[].proper_subset?([]) }.should raise_error(ArgumentError)
-    -> { Set[].proper_subset?(1) }.should raise_error(ArgumentError)
-    -> { Set[].proper_subset?("test") }.should raise_error(ArgumentError)
-    -> { Set[].proper_subset?(Object.new) }.should raise_error(ArgumentError)
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true if passed a Set-like object that self is a proper subset of" do
-      Set[1, 2, 3].proper_subset?(SetSpecs::SetLike.new([1, 2, 3, 4])).should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/set/proper_superset_spec.rb b/spec/ruby/library/set/proper_superset_spec.rb
deleted file mode 100644
index a386c8c097..0000000000
--- a/spec/ruby/library/set/proper_superset_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#proper_superset?" do
-  before :each do
-    @set = Set[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a Set that self is a proper superset of" do
-    @set.proper_superset?(Set[]).should be_true
-    Set[1, 2, 3].proper_superset?(Set[]).should be_true
-    Set["a", :b, ?c].proper_superset?(Set[]).should be_true
-
-    @set.proper_superset?(Set[1, 2, 3]).should be_true
-    @set.proper_superset?(Set[1, 3]).should be_true
-    @set.proper_superset?(Set[1, 2]).should be_true
-    @set.proper_superset?(Set[1]).should be_true
-
-    @set.proper_superset?(Set[5]).should be_false
-    @set.proper_superset?(Set[1, 5]).should be_false
-    @set.proper_superset?(Set[nil]).should be_false
-    @set.proper_superset?(Set["test"]).should be_false
-
-    @set.proper_superset?(@set).should be_false
-    Set[].proper_superset?(Set[]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-Set" do
-    -> { Set[].proper_superset?([]) }.should raise_error(ArgumentError)
-    -> { Set[].proper_superset?(1) }.should raise_error(ArgumentError)
-    -> { Set[].proper_superset?("test") }.should raise_error(ArgumentError)
-    -> { Set[].proper_superset?(Object.new) }.should raise_error(ArgumentError)
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true if passed a Set-like object that self is a proper superset of" do
-      Set[1, 2, 3, 4].proper_superset?(SetSpecs::SetLike.new([1, 2, 3])).should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/set/reject_spec.rb b/spec/ruby/library/set/reject_spec.rb
deleted file mode 100644
index 9131f960ad..0000000000
--- a/spec/ruby/library/set/reject_spec.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#reject!" do
-  before :each do
-    @set = Set["one", "two", "three"]
-  end
-
-  it "yields every element of self" do
-    ret = []
-    @set.reject! { |x| ret << x }
-    ret.sort.should == ["one", "two", "three"].sort
-  end
-
-  it "deletes every element from self for which the passed block returns true" do
-    @set.reject! { |x| x.size == 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self when self was modified" do
-    @set.reject! { |x| true }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.reject! { |x| false }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.reject!
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size == 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/replace_spec.rb b/spec/ruby/library/set/replace_spec.rb
deleted file mode 100644
index 7511066c9c..0000000000
--- a/spec/ruby/library/set/replace_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#replace" do
-  before :each do
-    @set = Set[:a, :b, :c]
-  end
-
-  it "replaces the contents with other and returns self" do
-    @set.replace(Set[1, 2, 3]).should == @set
-    @set.should == Set[1, 2, 3]
-  end
-
-  it "accepts any enumerable as other" do
-    @set.replace([1, 2, 3]).should == Set[1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/shared/add.rb b/spec/ruby/library/set/shared/add.rb
deleted file mode 100644
index 9e797f5df9..0000000000
--- a/spec/ruby/library/set/shared/add.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-describe :set_add, shared: true do
-  before :each do
-    @set = Set.new
-  end
-
-  it "adds the passed Object to self" do
-    @set.send(@method, "dog")
-    @set.should include("dog")
-  end
-
-  it "returns self" do
-    @set.send(@method, "dog").should equal(@set)
-  end
-end
diff --git a/spec/ruby/library/set/shared/collect.rb b/spec/ruby/library/set/shared/collect.rb
deleted file mode 100644
index bc58c231be..0000000000
--- a/spec/ruby/library/set/shared/collect.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-describe :set_collect_bang, shared: true do
-  before :each do
-    @set = Set[1, 2, 3, 4, 5]
-  end
-
-  it "yields each Object in self" do
-    res = []
-    @set.send(@method) { |x| res << x }
-    res.sort.should == [1, 2, 3, 4, 5].sort
-  end
-
-  it "returns self" do
-    @set.send(@method) { |x| x }.should equal(@set)
-  end
-
-  it "replaces self with the return values of the block" do
-    @set.send(@method) { |x| x * 2 }
-    @set.should == Set[2, 4, 6, 8, 10]
-  end
-end
diff --git a/spec/ruby/library/set/shared/difference.rb b/spec/ruby/library/set/shared/difference.rb
deleted file mode 100644
index f88987ed2a..0000000000
--- a/spec/ruby/library/set/shared/difference.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :set_difference, shared: true do
-  before :each do
-    @set = Set[:a, :b, :c]
-  end
-
-  it "returns a new Set containing self's elements excluding the elements in the passed Enumerable" do
-    @set.send(@method, Set[:a, :b]).should == Set[:c]
-    @set.send(@method, [:b, :c]).should == Set[:a]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/shared/include.rb b/spec/ruby/library/set/shared/include.rb
deleted file mode 100644
index b4d95cde24..0000000000
--- a/spec/ruby/library/set/shared/include.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-describe :set_include, shared: true do
-  it "returns true when self contains the passed Object" do
-    set = Set[:a, :b, :c]
-    set.send(@method, :a).should be_true
-    set.send(@method, :e).should be_false
-  end
-
-  describe "member equality" do
-    it "is checked using both #hash and #eql?" do
-      obj = Object.new
-      obj_another = Object.new
-
-      def obj.hash; 42 end
-      def obj_another.hash; 42 end
-      def obj_another.eql?(o) hash == o.hash end
-
-      set = Set["a", "b", "c", obj]
-      set.send(@method, obj_another).should == true
-    end
-
-    it "is not checked using #==" do
-      obj = Object.new
-      set = Set["a", "b", "c"]
-
-      obj.should_not_receive(:==)
-      set.send(@method, obj)
-    end
-  end
-end
diff --git a/spec/ruby/library/set/shared/inspect.rb b/spec/ruby/library/set/shared/inspect.rb
deleted file mode 100644
index 69fbdd12f6..0000000000
--- a/spec/ruby/library/set/shared/inspect.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe "set_inspect", shared: true do
-  it "returns a String representation of self" do
-    Set[].send(@method).should be_kind_of(String)
-    Set[nil, false, true].send(@method).should be_kind_of(String)
-    Set[1, 2, 3].send(@method).should be_kind_of(String)
-    Set["1", "2", "3"].send(@method).should be_kind_of(String)
-    Set[:a, "b", Set[?c]].send(@method).should be_kind_of(String)
-  end
-
-  it "correctly handles self-references" do
-    (set = Set[]) << set
-    set.send(@method).should be_kind_of(String)
-    set.send(@method).should include("#<Set: {...}>")
-  end
-end
diff --git a/spec/ruby/library/set/shared/intersection.rb b/spec/ruby/library/set/shared/intersection.rb
deleted file mode 100644
index 5ae4199c94..0000000000
--- a/spec/ruby/library/set/shared/intersection.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :set_intersection, shared: true do
-  before :each do
-    @set = Set[:a, :b, :c]
-  end
-
-  it "returns a new Set containing only elements shared by self and the passed Enumerable" do
-    @set.send(@method, Set[:b, :c, :d, :e]).should == Set[:b, :c]
-    @set.send(@method, [:b, :c, :d]).should == Set[:b, :c]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/shared/select.rb b/spec/ruby/library/set/shared/select.rb
deleted file mode 100644
index 2108d398b4..0000000000
--- a/spec/ruby/library/set/shared/select.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe :set_select_bang, shared: true do
-  before :each do
-    @set = Set["one", "two", "three"]
-  end
-
-  it "yields every element of self" do
-    ret = []
-    @set.send(@method) { |x| ret << x }
-    ret.sort.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.send(@method) { |x| x.size != 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self when self was modified" do
-    @set.send(@method) { false }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.send(@method) { true }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.send(@method)
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/shared/union.rb b/spec/ruby/library/set/shared/union.rb
deleted file mode 100644
index 314f0e852d..0000000000
--- a/spec/ruby/library/set/shared/union.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :set_union, shared: true do
-  before :each do
-    @set = Set[:a, :b, :c]
-  end
-
-  it "returns a new Set containing all elements of self and the passed Enumerable" do
-    @set.send(@method, Set[:b, :d, :e]).should == Set[:a, :b, :c, :d, :e]
-    @set.send(@method, [:b, :e]).should == Set[:a, :b, :c, :e]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/size_spec.rb b/spec/ruby/library/set/size_spec.rb
deleted file mode 100644
index 3c8cb38517..0000000000
--- a/spec/ruby/library/set/size_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/length'
-require 'set'
-
-describe "Set#size" do
-  it_behaves_like :set_length, :size
-end
diff --git a/spec/ruby/library/set/sortedset/add_spec.rb b/spec/ruby/library/set/sortedset/add_spec.rb
deleted file mode 100644
index 5f8bde02f5..0000000000
--- a/spec/ruby/library/set/sortedset/add_spec.rb
+++ /dev/null
@@ -1,39 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/add'
-
-describe "SortedSet#add" do
-  it_behaves_like :sorted_set_add, :add
-
-  it "takes only values which responds <=>" do
-    obj = mock('no_comparison_operator')
-    obj.stub!(:respond_to?).with(:<=>).and_return(false)
-    -> { SortedSet["hello"].add(obj) }.should raise_error(ArgumentError)
-  end
-
-  it "raises on incompatible <=> comparison" do
-    # Use #to_a here as elements are sorted only when needed.
-    # Therefore the <=> incompatibility is only noticed on sorting.
-    -> { SortedSet['1', '2'].add(3).to_a }.should raise_error(ArgumentError)
-  end
-end
-
-describe "SortedSet#add?" do
-  before :each do
-    @set = SortedSet.new
-  end
-
-  it "adds the passed Object to self" do
-    @set.add?("cat")
-    @set.should include("cat")
-  end
-
-  it "returns self when the Object has not yet been added to self" do
-    @set.add?("cat").should equal(@set)
-  end
-
-  it "returns nil when the Object has already been added to self" do
-    @set.add?("cat")
-    @set.add?("cat").should be_nil
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/append_spec.rb b/spec/ruby/library/set/sortedset/append_spec.rb
deleted file mode 100644
index ebcceba962..0000000000
--- a/spec/ruby/library/set/sortedset/append_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/add'
-
-describe "SortedSet#<<" do
-  it_behaves_like :sorted_set_add, :<<
-end
diff --git a/spec/ruby/library/set/sortedset/case_equality_spec.rb b/spec/ruby/library/set/sortedset/case_equality_spec.rb
deleted file mode 100644
index 5627917677..0000000000
--- a/spec/ruby/library/set/sortedset/case_equality_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-ruby_version_is "2.5" do
-  describe "SortedSet#===" do
-    it_behaves_like :sorted_set_include, :===
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/classify_spec.rb b/spec/ruby/library/set/sortedset/classify_spec.rb
deleted file mode 100644
index 62b26d5d28..0000000000
--- a/spec/ruby/library/set/sortedset/classify_spec.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#classify" do
-  before :each do
-    @set = SortedSet["one", "two", "three", "four"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    res = []
-    @set.classify { |x| res << x }
-    res.should == ["one", "two", "three", "four"].sort
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.classify
-    enum.should be_an_instance_of(Enumerator)
-
-    classified = enum.each { |x| x.length }
-    classified.should == { 3 => SortedSet["one", "two"], 4 => SortedSet["four"], 5 => SortedSet["three"] }
-  end
-
-  it "classifies the Objects in self based on the block's return value" do
-    classified = @set.classify { |x| x.length }
-    classified.should == { 3 => SortedSet["one", "two"], 4 => SortedSet["four"], 5 => SortedSet["three"] }
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/clear_spec.rb b/spec/ruby/library/set/sortedset/clear_spec.rb
deleted file mode 100644
index 11b5db2095..0000000000
--- a/spec/ruby/library/set/sortedset/clear_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#clear" do
-  before :each do
-    @set = SortedSet["one", "two", "three", "four"]
-  end
-
-  it "removes all elements from self" do
-    @set.clear
-    @set.should be_empty
-  end
-
-  it "returns self" do
-    @set.clear.should equal(@set)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/collect_spec.rb b/spec/ruby/library/set/sortedset/collect_spec.rb
deleted file mode 100644
index 21ead4fe55..0000000000
--- a/spec/ruby/library/set/sortedset/collect_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/collect'
-
-describe "SortedSet#collect!" do
-  it_behaves_like :sorted_set_collect_bang, :collect!
-end
diff --git a/spec/ruby/library/set/sortedset/constructor_spec.rb b/spec/ruby/library/set/sortedset/constructor_spec.rb
deleted file mode 100644
index 953144dbdb..0000000000
--- a/spec/ruby/library/set/sortedset/constructor_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet[]" do
-  it "returns a new SortedSet populated with the passed Objects" do
-    set = SortedSet[1, 2, 3]
-
-    set.instance_of?(SortedSet).should be_true
-    set.size.should eql(3)
-
-    set.should include(1)
-    set.should include(2)
-    set.should include(3)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/delete_if_spec.rb b/spec/ruby/library/set/sortedset/delete_if_spec.rb
deleted file mode 100644
index 1ff689376a..0000000000
--- a/spec/ruby/library/set/sortedset/delete_if_spec.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#delete_if" do
-  before :each do
-    @set = SortedSet["one", "two", "three"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    ret = []
-    @set.delete_if { |x| ret << x }
-    ret.should == ["one", "two", "three"].sort
-  end
-
-  it "deletes every element from self for which the passed block returns true" do
-    @set.delete_if { |x| x.size == 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self" do
-    @set.delete_if { |x| x }.should equal(@set)
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.delete_if
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size == 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/delete_spec.rb b/spec/ruby/library/set/sortedset/delete_spec.rb
deleted file mode 100644
index 71583c7f13..0000000000
--- a/spec/ruby/library/set/sortedset/delete_spec.rb
+++ /dev/null
@@ -1,37 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#delete" do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "deletes the passed Object from self" do
-    @set.delete("a")
-    @set.should_not include("a")
-  end
-
-  it "returns self" do
-    @set.delete("a").should equal(@set)
-    @set.delete("x").should equal(@set)
-  end
-end
-
-describe "SortedSet#delete?" do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "deletes the passed Object from self" do
-    @set.delete?("a")
-    @set.should_not include("a")
-  end
-
-  it "returns self when the passed Object is in self" do
-    @set.delete?("a").should equal(@set)
-  end
-
-  it "returns nil when the passed Object is not in self" do
-    @set.delete?("x").should be_nil
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/difference_spec.rb b/spec/ruby/library/set/sortedset/difference_spec.rb
deleted file mode 100644
index c3d679aff8..0000000000
--- a/spec/ruby/library/set/sortedset/difference_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/difference'
-
-describe "SortedSet#difference" do
-  it_behaves_like :sorted_set_difference, :difference
-end
diff --git a/spec/ruby/library/set/sortedset/divide_spec.rb b/spec/ruby/library/set/sortedset/divide_spec.rb
deleted file mode 100644
index 4b2135a8c9..0000000000
--- a/spec/ruby/library/set/sortedset/divide_spec.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#divide" do
-  it "divides self into a set of subsets based on the blocks return values" do
-    set = SortedSet["one", "two", "three", "four", "five"].divide { |x| x.length }
-    set.map { |x| x.to_a }.to_a.sort.should == [["five", "four"], ["one", "two"], ["three"]]
-  end
-
-  it "yields each Object in self in sorted order" do
-    ret = []
-    SortedSet["one", "two", "three", "four", "five"].divide { |x| ret << x }
-    ret.should == ["one", "two", "three", "four", "five"].sort
-  end
-
-  # BUG: Does not raise a LocalJumpError, but a NoMethodError
-  #
-  # it "raises a LocalJumpError when not passed a block" do
-  #   lambda { SortedSet[1].divide }.should raise_error(LocalJumpError)
-  # end
-end
-
-describe "SortedSet#divide when passed a block with an arity of 2" do
-  it "divides self into a set of subsets based on the blocks return values" do
-    set = SortedSet[1, 3, 4, 6, 9, 10, 11].divide { |x, y| (x - y).abs == 1 }
-    set.map { |x| x.to_a }.to_a.sort.should == [[1], [3, 4], [6], [9, 10, 11]]
-  end
-
-  it "yields each two Objects to the block" do
-    ret = []
-    SortedSet[1, 2].divide { |x, y| ret << [x, y] }
-    ret.should == [[1, 1], [1, 2], [2, 1], [2, 2]]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/each_spec.rb b/spec/ruby/library/set/sortedset/each_spec.rb
deleted file mode 100644
index bcf0d74d1f..0000000000
--- a/spec/ruby/library/set/sortedset/each_spec.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#each" do
-  before :each do
-    @set = SortedSet[1, 2, 3]
-  end
-
-  it "yields each Object in self in sorted order" do
-    ret = []
-    SortedSet["one", "two", "three"].each { |x| ret << x }
-    ret.should == ["one", "two", "three"].sort
-  end
-
-  it "returns self" do
-    @set.each { |x| x }.should equal(@set)
-  end
-
-  it "returns an Enumerator when not passed a block" do
-    enum = @set.each
-
-    ret = []
-    enum.each { |x| ret << x }
-    ret.sort.should == [1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/empty_spec.rb b/spec/ruby/library/set/sortedset/empty_spec.rb
deleted file mode 100644
index deb3b567fb..0000000000
--- a/spec/ruby/library/set/sortedset/empty_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#empty?" do
-  it "returns true if self is empty" do
-    SortedSet[].empty?.should be_true
-    SortedSet[1].empty?.should be_false
-    SortedSet[1,2,3].empty?.should be_false
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/eql_spec.rb b/spec/ruby/library/set/sortedset/eql_spec.rb
deleted file mode 100644
index b22858a362..0000000000
--- a/spec/ruby/library/set/sortedset/eql_spec.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#eql?" do
-  it "returns true when the passed argument is a SortedSet and contains the same elements" do
-    SortedSet[].should eql(SortedSet[])
-    SortedSet[1, 2, 3].should eql(SortedSet[1, 2, 3])
-    SortedSet[1, 2, 3].should eql(SortedSet[3, 2, 1])
-
-#    SortedSet["a", :b, ?c].should eql(SortedSet[?c, :b, "a"])
-
-    SortedSet[1, 2, 3].should_not eql(SortedSet[1.0, 2, 3])
-    SortedSet[1, 2, 3].should_not eql(SortedSet[2, 3])
-    SortedSet[1, 2, 3].should_not eql(SortedSet[])
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/equal_value_spec.rb b/spec/ruby/library/set/sortedset/equal_value_spec.rb
deleted file mode 100644
index cb1b7c9443..0000000000
--- a/spec/ruby/library/set/sortedset/equal_value_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#==" do
-  it "returns true when the passed Object is a SortedSet and self and the Object contain the same elements" do
-    SortedSet[].should == SortedSet[]
-    SortedSet[1, 2, 3].should == SortedSet[1, 2, 3]
-    SortedSet["1", "2", "3"].should == SortedSet["1", "2", "3"]
-
-    SortedSet[1, 2, 3].should_not == SortedSet[1.0, 2, 3]
-    SortedSet[1, 2, 3].should_not == [1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/exclusion_spec.rb b/spec/ruby/library/set/sortedset/exclusion_spec.rb
deleted file mode 100644
index d0f1ab95cb..0000000000
--- a/spec/ruby/library/set/sortedset/exclusion_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#^" do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns a new SortedSet containing elements that are not in both self and the passed Enumerable" do
-    (@set ^ SortedSet[3, 4, 5]).should == SortedSet[1, 2, 5]
-    (@set ^ [3, 4, 5]).should == SortedSet[1, 2, 5]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set ^ 3 }.should raise_error(ArgumentError)
-    -> { @set ^ Object.new }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/filter_spec.rb b/spec/ruby/library/set/sortedset/filter_spec.rb
deleted file mode 100644
index cfaa8b2729..0000000000
--- a/spec/ruby/library/set/sortedset/filter_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/select'
-require 'set'
-
-ruby_version_is "2.6" do
-  describe "SortedSet#filter!" do
-    it_behaves_like :sorted_set_select_bang, :filter!
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/flatten_merge_spec.rb b/spec/ruby/library/set/sortedset/flatten_merge_spec.rb
deleted file mode 100644
index 9a8ed13f00..0000000000
--- a/spec/ruby/library/set/sortedset/flatten_merge_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#flatten_merge" do
-  it "is protected" do
-    SortedSet.should have_protected_instance_method("flatten_merge")
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/flatten_spec.rb b/spec/ruby/library/set/sortedset/flatten_spec.rb
deleted file mode 100644
index ca4e4637e6..0000000000
--- a/spec/ruby/library/set/sortedset/flatten_spec.rb
+++ /dev/null
@@ -1,44 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-# Note: Flatten make little sens on sorted sets, because SortedSets are not (by default)
-# comparable. For a SortedSet to be both valid and nested, we need to define a comparison operator:
-module SortedSet_FlattenSpecs
-  class ComparableSortedSet < SortedSet
-    def <=>(other)
-      return puts "#{other} vs #{self}" unless other.is_a?(ComparableSortedSet)
-      to_a <=> other.to_a
-    end
-  end
-end
-
-describe "SortedSet#flatten" do
-  it "returns a copy of self with each included SortedSet flattened" do
-    klass = SortedSet_FlattenSpecs::ComparableSortedSet
-    set = klass[klass[1,2], klass[3,4], klass[5,6,7], klass[8]]
-    flattened_set = set.flatten
-
-    flattened_set.should_not equal(set)
-    flattened_set.should == klass[1, 2, 3, 4, 5, 6, 7, 8]
-  end
-end
-
-describe "SortedSet#flatten!" do
-  it "flattens self" do
-    klass = SortedSet_FlattenSpecs::ComparableSortedSet
-    set = klass[klass[1,2], klass[3,4], klass[5,6,7], klass[8]]
-    set.flatten!
-    set.should == klass[1, 2, 3, 4, 5, 6, 7, 8]
-  end
-
-  it "returns self when self was modified" do
-    klass = SortedSet_FlattenSpecs::ComparableSortedSet
-    set = klass[klass[1,2], klass[3,4]]
-    set.flatten!.should equal(set)
-  end
-
-  it "returns nil when self was not modified" do
-    set = SortedSet[1, 2, 3, 4]
-    set.flatten!.should be_nil
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/hash_spec.rb b/spec/ruby/library/set/sortedset/hash_spec.rb
deleted file mode 100644
index 7833c68a10..0000000000
--- a/spec/ruby/library/set/sortedset/hash_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#hash" do
-  it "is static" do
-    SortedSet[].hash.should == SortedSet[].hash
-    SortedSet[1, 2, 3].hash.should == SortedSet[1, 2, 3].hash
-    SortedSet["a", "b", "c"].hash.should == SortedSet["c", "b", "a"].hash
-
-    SortedSet[].hash.should_not == SortedSet[1, 2, 3].hash
-    SortedSet[1, 2, 3].hash.should_not == SortedSet["a", "b", "c"].hash
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/include_spec.rb b/spec/ruby/library/set/sortedset/include_spec.rb
deleted file mode 100644
index 030a9e146a..0000000000
--- a/spec/ruby/library/set/sortedset/include_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-describe "SortedSet#include?" do
-  it_behaves_like :sorted_set_include, :include?
-end
diff --git a/spec/ruby/library/set/sortedset/initialize_spec.rb b/spec/ruby/library/set/sortedset/initialize_spec.rb
deleted file mode 100644
index 1238f4efc4..0000000000
--- a/spec/ruby/library/set/sortedset/initialize_spec.rb
+++ /dev/null
@@ -1,30 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#initialize" do
-  it "is private" do
-    SortedSet.should have_private_instance_method("initialize")
-  end
-
-  it "adds all elements of the passed Enumerable to self" do
-    s = SortedSet.new([1, 2, 3])
-    s.size.should eql(3)
-    s.should include(1)
-    s.should include(2)
-    s.should include(3)
-  end
-
-  it "preprocesses all elements by a passed block before adding to self" do
-    s = SortedSet.new([1, 2, 3]) { |x| x * x }
-    s.size.should eql(3)
-    s.should include(1)
-    s.should include(4)
-    s.should include(9)
-  end
-
-  it "raises on incompatible <=> comparison" do
-    # Use #to_a here as elements are sorted only when needed.
-    # Therefore the <=> incompatibility is only noticed on sorting.
-    -> { SortedSet.new(['00', nil]).to_a }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/inspect_spec.rb b/spec/ruby/library/set/sortedset/inspect_spec.rb
deleted file mode 100644
index 7103bee3f5..0000000000
--- a/spec/ruby/library/set/sortedset/inspect_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#inspect" do
-  it "returns a String representation of self" do
-    SortedSet[].inspect.should be_kind_of(String)
-    SortedSet[1, 2, 3].inspect.should be_kind_of(String)
-    SortedSet["1", "2", "3"].inspect.should be_kind_of(String)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/intersection_spec.rb b/spec/ruby/library/set/sortedset/intersection_spec.rb
deleted file mode 100644
index 6ff9c80ce1..0000000000
--- a/spec/ruby/library/set/sortedset/intersection_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/intersection'
-require 'set'
-
-describe "SortedSet#intersection" do
-  it_behaves_like :sorted_set_intersection, :intersection
-end
-
-describe "SortedSet#&" do
-  it_behaves_like :sorted_set_intersection, :&
-end
diff --git a/spec/ruby/library/set/sortedset/keep_if_spec.rb b/spec/ruby/library/set/sortedset/keep_if_spec.rb
deleted file mode 100644
index 2235eb3766..0000000000
--- a/spec/ruby/library/set/sortedset/keep_if_spec.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#keep_if" do
-  before :each do
-    @set = SortedSet["one", "two", "three"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    ret = []
-    @set.keep_if { |x| ret << x }
-    ret.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.keep_if { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
-
-  it "returns self" do
-    @set.keep_if {}.should equal(@set)
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.keep_if
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/length_spec.rb b/spec/ruby/library/set/sortedset/length_spec.rb
deleted file mode 100644
index 5f138dd6f7..0000000000
--- a/spec/ruby/library/set/sortedset/length_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/length'
-require 'set'
-
-describe "SortedSet#length" do
-  it_behaves_like :sorted_set_length, :length
-end
diff --git a/spec/ruby/library/set/sortedset/map_spec.rb b/spec/ruby/library/set/sortedset/map_spec.rb
deleted file mode 100644
index 1d7b5954e5..0000000000
--- a/spec/ruby/library/set/sortedset/map_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/collect'
-
-describe "SortedSet#map!" do
-  it_behaves_like :sorted_set_collect_bang, :map!
-end
diff --git a/spec/ruby/library/set/sortedset/member_spec.rb b/spec/ruby/library/set/sortedset/member_spec.rb
deleted file mode 100644
index d6005557ab..0000000000
--- a/spec/ruby/library/set/sortedset/member_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/include'
-require 'set'
-
-describe "SortedSet#member?" do
-  it_behaves_like :sorted_set_include, :member?
-end
diff --git a/spec/ruby/library/set/sortedset/merge_spec.rb b/spec/ruby/library/set/sortedset/merge_spec.rb
deleted file mode 100644
index 31570ad4db..0000000000
--- a/spec/ruby/library/set/sortedset/merge_spec.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#merge" do
-  it "adds the elements of the passed Enumerable to self" do
-    SortedSet["a", "b"].merge(SortedSet["b", "c", "d"]).should == SortedSet["a", "b", "c", "d"]
-    SortedSet[1, 2].merge([3, 4]).should == SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns self" do
-    set = SortedSet[1, 2]
-    set.merge([3, 4]).should equal(set)
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { SortedSet[1, 2].merge(1) }.should raise_error(ArgumentError)
-    -> { SortedSet[1, 2].merge(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/minus_spec.rb b/spec/ruby/library/set/sortedset/minus_spec.rb
deleted file mode 100644
index ffb8ee85d1..0000000000
--- a/spec/ruby/library/set/sortedset/minus_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-require_relative 'shared/difference'
-
-describe "SortedSet#-" do
-  it_behaves_like :sorted_set_difference, :-
-end
diff --git a/spec/ruby/library/set/sortedset/plus_spec.rb b/spec/ruby/library/set/sortedset/plus_spec.rb
deleted file mode 100644
index 355c775d7e..0000000000
--- a/spec/ruby/library/set/sortedset/plus_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/union'
-require 'set'
-
-describe "SortedSet#+" do
-  it_behaves_like :sorted_set_union, :+
-end
diff --git a/spec/ruby/library/set/sortedset/pretty_print_cycle_spec.rb b/spec/ruby/library/set/sortedset/pretty_print_cycle_spec.rb
deleted file mode 100644
index fe15f1bf7d..0000000000
--- a/spec/ruby/library/set/sortedset/pretty_print_cycle_spec.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#pretty_print_cycle" do
-  it "passes the 'pretty print' representation of a self-referencing SortedSet to the pretty print writer" do
-    pp = mock("PrettyPrint")
-    pp.should_receive(:text).with("#<SortedSet: {...}>")
-    SortedSet[1, 2, 3].pretty_print_cycle(pp)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/pretty_print_spec.rb b/spec/ruby/library/set/sortedset/pretty_print_spec.rb
deleted file mode 100644
index 601ff4d182..0000000000
--- a/spec/ruby/library/set/sortedset/pretty_print_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#pretty_print" do
-  it "passes the 'pretty print' representation of self to the pretty print writer" do
-    pp = mock("PrettyPrint")
-    set = SortedSet[1, 2, 3]
-
-    pp.should_receive(:text).with("#<SortedSet: {")
-    pp.should_receive(:text).with("}>")
-
-    pp.should_receive(:nest).with(1).and_yield
-    pp.should_receive(:seplist).with(set)
-
-    set.pretty_print(pp)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/proper_subset_spec.rb b/spec/ruby/library/set/sortedset/proper_subset_spec.rb
deleted file mode 100644
index 818173a7f9..0000000000
--- a/spec/ruby/library/set/sortedset/proper_subset_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#proper_subset?" do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a SortedSet that self is a proper subset of" do
-    SortedSet[].proper_subset?(@set).should be_true
-    SortedSet[].proper_subset?(SortedSet[1, 2, 3]).should be_true
-    SortedSet[].proper_subset?(SortedSet["a", "b", "c"]).should be_true
-
-    SortedSet[1, 2, 3].proper_subset?(@set).should be_true
-    SortedSet[1, 3].proper_subset?(@set).should be_true
-    SortedSet[1, 2].proper_subset?(@set).should be_true
-    SortedSet[1].proper_subset?(@set).should be_true
-
-    SortedSet[5].proper_subset?(@set).should be_false
-    SortedSet[1, 5].proper_subset?(@set).should be_false
-    SortedSet["test"].proper_subset?(@set).should be_false
-
-    @set.proper_subset?(@set).should be_false
-    SortedSet[].proper_subset?(SortedSet[]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-SortedSet" do
-    -> { SortedSet[].proper_subset?([]) }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_subset?(1) }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_subset?("test") }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_subset?(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/proper_superset_spec.rb b/spec/ruby/library/set/sortedset/proper_superset_spec.rb
deleted file mode 100644
index 2699290f0e..0000000000
--- a/spec/ruby/library/set/sortedset/proper_superset_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#proper_superset?" do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a SortedSet that self is a proper superset of" do
-    @set.proper_superset?(SortedSet[]).should be_true
-    SortedSet[1, 2, 3].proper_superset?(SortedSet[]).should be_true
-    SortedSet["a", "b", "c"].proper_superset?(SortedSet[]).should be_true
-
-    @set.proper_superset?(SortedSet[1, 2, 3]).should be_true
-    @set.proper_superset?(SortedSet[1, 3]).should be_true
-    @set.proper_superset?(SortedSet[1, 2]).should be_true
-    @set.proper_superset?(SortedSet[1]).should be_true
-
-    @set.proper_superset?(SortedSet[5]).should be_false
-    @set.proper_superset?(SortedSet[1, 5]).should be_false
-    @set.proper_superset?(SortedSet["test"]).should be_false
-
-    @set.proper_superset?(@set).should be_false
-    SortedSet[].proper_superset?(SortedSet[]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-SortedSet" do
-    -> { SortedSet[].proper_superset?([]) }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_superset?(1) }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_superset?("test") }.should raise_error(ArgumentError)
-    -> { SortedSet[].proper_superset?(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/reject_spec.rb b/spec/ruby/library/set/sortedset/reject_spec.rb
deleted file mode 100644
index da2a76e7a7..0000000000
--- a/spec/ruby/library/set/sortedset/reject_spec.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#reject!" do
-  before :each do
-    @set = SortedSet["one", "two", "three"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    res = []
-    @set.reject! { |x| res << x }
-    res.should == ["one", "two", "three"].sort
-  end
-
-  it "deletes every element from self for which the passed block returns true" do
-    @set.reject! { |x| x.size == 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self when self was modified" do
-    @set.reject! { |x| true }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.reject! { |x| false }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.reject!
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size == 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/replace_spec.rb b/spec/ruby/library/set/sortedset/replace_spec.rb
deleted file mode 100644
index 2a7fa73efb..0000000000
--- a/spec/ruby/library/set/sortedset/replace_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#replace" do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "replaces the contents with other and returns self" do
-    @set.replace(SortedSet[1, 2, 3]).should == @set
-    @set.should == SortedSet[1, 2, 3]
-  end
-
-  it "accepts any enumerable as other" do
-    @set.replace([1, 2, 3]).should == SortedSet[1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/select_spec.rb b/spec/ruby/library/set/sortedset/select_spec.rb
deleted file mode 100644
index 68326cd02c..0000000000
--- a/spec/ruby/library/set/sortedset/select_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/select'
-require 'set'
-
-describe "SortedSet#select!" do
-  it_behaves_like :sorted_set_select_bang, :select!
-end
diff --git a/spec/ruby/library/set/sortedset/shared/add.rb b/spec/ruby/library/set/sortedset/shared/add.rb
deleted file mode 100644
index 95ef1b090e..0000000000
--- a/spec/ruby/library/set/sortedset/shared/add.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-describe :sorted_set_add, shared: true do
-  before :each do
-    @set = SortedSet.new
-  end
-
-  it "adds the passed Object to self" do
-    @set.send(@method, "dog")
-    @set.should include("dog")
-  end
-
-  it "returns self" do
-    @set.send(@method, "dog").should equal(@set)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/collect.rb b/spec/ruby/library/set/sortedset/shared/collect.rb
deleted file mode 100644
index e53304d427..0000000000
--- a/spec/ruby/library/set/sortedset/shared/collect.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-describe :sorted_set_collect_bang, shared: true do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4, 5]
-  end
-
-  it "yields each Object in self in sorted order" do
-    res = []
-    SortedSet["one", "two", "three"].send(@method) { |x| res << x; x }
-    res.should == ["one", "two", "three"].sort
-  end
-
-  it "returns self" do
-    @set.send(@method) { |x| x }.should equal(@set)
-  end
-
-  it "replaces self with the return values of the block" do
-    @set.send(@method) { |x| x * 2 }
-    @set.should == SortedSet[2, 4, 6, 8, 10]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/difference.rb b/spec/ruby/library/set/sortedset/shared/difference.rb
deleted file mode 100644
index 688e23a7a7..0000000000
--- a/spec/ruby/library/set/sortedset/shared/difference.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :sorted_set_difference, shared: true do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "returns a new SortedSet containing self's elements excluding the elements in the passed Enumerable" do
-    @set.send(@method, SortedSet["a", "b"]).should == SortedSet["c"]
-    @set.send(@method, ["b", "c"]).should == SortedSet["a"]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/include.rb b/spec/ruby/library/set/sortedset/shared/include.rb
deleted file mode 100644
index cd1758819d..0000000000
--- a/spec/ruby/library/set/sortedset/shared/include.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-describe :sorted_set_include, shared: true do
-  it "returns true when self contains the passed Object" do
-    set = SortedSet["a", "b", "c"]
-    set.send(@method, "a").should be_true
-    set.send(@method, "e").should be_false
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/intersection.rb b/spec/ruby/library/set/sortedset/shared/intersection.rb
deleted file mode 100644
index 045716ad05..0000000000
--- a/spec/ruby/library/set/sortedset/shared/intersection.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :sorted_set_intersection, shared: true do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "returns a new SortedSet containing only elements shared by self and the passed Enumerable" do
-    @set.send(@method, SortedSet["b", "c", "d", "e"]).should == SortedSet["b", "c"]
-    @set.send(@method, ["b", "c", "d"]).should == SortedSet["b", "c"]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/length.rb b/spec/ruby/library/set/sortedset/shared/length.rb
deleted file mode 100644
index d1dfee1cff..0000000000
--- a/spec/ruby/library/set/sortedset/shared/length.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-describe :sorted_set_length, shared: true do
-  it "returns the number of elements in the set" do
-    set = SortedSet["a", "b", "c"]
-    set.send(@method).should == 3
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/select.rb b/spec/ruby/library/set/sortedset/shared/select.rb
deleted file mode 100644
index e13311eda5..0000000000
--- a/spec/ruby/library/set/sortedset/shared/select.rb
+++ /dev/null
@@ -1,35 +0,0 @@
-require_relative '../../../../spec_helper'
-require 'set'
-
-describe :sorted_set_select_bang, shared: true do
-  before :each do
-    @set = SortedSet["one", "two", "three"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    res = []
-    @set.send(@method) { |x| res << x }
-    res.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.send(@method) { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
-
-  it "returns self when self was modified" do
-    @set.send(@method) { false }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.send(@method) { true }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.send(@method)
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/shared/union.rb b/spec/ruby/library/set/sortedset/shared/union.rb
deleted file mode 100644
index 9015bdc8e3..0000000000
--- a/spec/ruby/library/set/sortedset/shared/union.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-describe :sorted_set_union, shared: true do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "returns a new SortedSet containing all elements of self and the passed Enumerable" do
-    @set.send(@method, SortedSet["b", "d", "e"]).should == SortedSet["a", "b", "c", "d", "e"]
-    @set.send(@method, ["b", "e"]).should == SortedSet["a", "b", "c", "e"]
-  end
-
-  it "raises an ArgumentError when passed a non-Enumerable" do
-    -> { @set.send(@method, 1) }.should raise_error(ArgumentError)
-    -> { @set.send(@method, Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/size_spec.rb b/spec/ruby/library/set/sortedset/size_spec.rb
deleted file mode 100644
index 13e5085b0c..0000000000
--- a/spec/ruby/library/set/sortedset/size_spec.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/length'
-require 'set'
-
-describe "SortedSet#size" do
-  it_behaves_like :sorted_set_length, :size
-end
diff --git a/spec/ruby/library/set/sortedset/subset_spec.rb b/spec/ruby/library/set/sortedset/subset_spec.rb
deleted file mode 100644
index 7768692df6..0000000000
--- a/spec/ruby/library/set/sortedset/subset_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#subset?" do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a SortedSet that is equal to self or self is a subset of" do
-    @set.subset?(@set).should be_true
-    SortedSet[].subset?(SortedSet[]).should be_true
-
-    SortedSet[].subset?(@set).should be_true
-    SortedSet[].subset?(SortedSet[1, 2, 3]).should be_true
-    SortedSet[].subset?(SortedSet["a", "b", "c"]).should be_true
-
-    SortedSet[1, 2, 3].subset?(@set).should be_true
-    SortedSet[1, 3].subset?(@set).should be_true
-    SortedSet[1, 2].subset?(@set).should be_true
-    SortedSet[1].subset?(@set).should be_true
-
-    SortedSet[5].subset?(@set).should be_false
-    SortedSet[1, 5].subset?(@set).should be_false
-    SortedSet["test"].subset?(@set).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-SortedSet" do
-    -> { SortedSet[].subset?([]) }.should raise_error(ArgumentError)
-    -> { SortedSet[].subset?(1) }.should raise_error(ArgumentError)
-    -> { SortedSet[].subset?("test") }.should raise_error(ArgumentError)
-    -> { SortedSet[].subset?(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/subtract_spec.rb b/spec/ruby/library/set/sortedset/subtract_spec.rb
deleted file mode 100644
index 64d66c3688..0000000000
--- a/spec/ruby/library/set/sortedset/subtract_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#subtract" do
-  before :each do
-    @set = SortedSet["a", "b", "c"]
-  end
-
-  it "deletes any elements contained in other and returns self" do
-    @set.subtract(SortedSet["b", "c"]).should == @set
-    @set.should == SortedSet["a"]
-  end
-
-  it "accepts any enumerable as other" do
-    @set.subtract(["c"]).should == SortedSet["a", "b"]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/superset_spec.rb b/spec/ruby/library/set/sortedset/superset_spec.rb
deleted file mode 100644
index 823781b860..0000000000
--- a/spec/ruby/library/set/sortedset/superset_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#superset?" do
-  before :each do
-    @set = SortedSet[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a SortedSet that equals self or self is a proper superset of" do
-    @set.superset?(@set).should be_true
-    SortedSet[].superset?(SortedSet[]).should be_true
-
-    @set.superset?(SortedSet[]).should be_true
-    SortedSet[1, 2, 3].superset?(SortedSet[]).should be_true
-    SortedSet["a", "b", "c"].superset?(SortedSet[]).should be_true
-
-    @set.superset?(SortedSet[1, 2, 3]).should be_true
-    @set.superset?(SortedSet[1, 3]).should be_true
-    @set.superset?(SortedSet[1, 2]).should be_true
-    @set.superset?(SortedSet[1]).should be_true
-
-    @set.superset?(SortedSet[5]).should be_false
-    @set.superset?(SortedSet[1, 5]).should be_false
-    @set.superset?(SortedSet["test"]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-SortedSet" do
-    -> { SortedSet[].superset?([]) }.should raise_error(ArgumentError)
-    -> { SortedSet[].superset?(1) }.should raise_error(ArgumentError)
-    -> { SortedSet[].superset?("test") }.should raise_error(ArgumentError)
-    -> { SortedSet[].superset?(Object.new) }.should raise_error(ArgumentError)
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/to_a_spec.rb b/spec/ruby/library/set/sortedset/to_a_spec.rb
deleted file mode 100644
index ba37d18cdb..0000000000
--- a/spec/ruby/library/set/sortedset/to_a_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../../spec_helper'
-require 'set'
-
-describe "SortedSet#to_a" do
-  it "returns an array containing elements" do
-    set = SortedSet.new [1, 2, 3]
-    set.to_a.should == [1, 2, 3]
-  end
-
-  it "returns a sorted array containing elements" do
-    set = SortedSet[2, 3, 1]
-    set.to_a.should == [1, 2, 3]
-
-    set = SortedSet.new [5, 6, 4, 4]
-    set.to_a.should == [4, 5, 6]
-  end
-end
diff --git a/spec/ruby/library/set/sortedset/union_spec.rb b/spec/ruby/library/set/sortedset/union_spec.rb
deleted file mode 100644
index eb77600fee..0000000000
--- a/spec/ruby/library/set/sortedset/union_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../../spec_helper'
-require_relative 'shared/union'
-require 'set'
-
-describe "SortedSet#union" do
-  it_behaves_like :sorted_set_union, :union
-end
-
-describe "SortedSet#|" do
-  it_behaves_like :sorted_set_union, :|
-end
diff --git a/spec/ruby/library/set/subset_spec.rb b/spec/ruby/library/set/subset_spec.rb
deleted file mode 100644
index f375efa6df..0000000000
--- a/spec/ruby/library/set/subset_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#subset?" do
-  before :each do
-    @set = Set[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a Set that is equal to self or self is a subset of" do
-    @set.subset?(@set).should be_true
-    Set[].subset?(Set[]).should be_true
-
-    Set[].subset?(@set).should be_true
-    Set[].subset?(Set[1, 2, 3]).should be_true
-    Set[].subset?(Set["a", :b, ?c]).should be_true
-
-    Set[1, 2, 3].subset?(@set).should be_true
-    Set[1, 3].subset?(@set).should be_true
-    Set[1, 2].subset?(@set).should be_true
-    Set[1].subset?(@set).should be_true
-
-    Set[5].subset?(@set).should be_false
-    Set[1, 5].subset?(@set).should be_false
-    Set[nil].subset?(@set).should be_false
-    Set["test"].subset?(@set).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-Set" do
-    -> { Set[].subset?([]) }.should raise_error(ArgumentError)
-    -> { Set[].subset?(1) }.should raise_error(ArgumentError)
-    -> { Set[].subset?("test") }.should raise_error(ArgumentError)
-    -> { Set[].subset?(Object.new) }.should raise_error(ArgumentError)
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true if passed a Set-like object that self is a subset of" do
-      Set[1, 2, 3].subset?(SetSpecs::SetLike.new([1, 2, 3, 4])).should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/set/subtract_spec.rb b/spec/ruby/library/set/subtract_spec.rb
deleted file mode 100644
index 56713de8b3..0000000000
--- a/spec/ruby/library/set/subtract_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#subtract" do
-  before :each do
-    @set = Set[:a, :b, :c]
-  end
-
-  it "deletes any elements contained in other and returns self" do
-    @set.subtract(Set[:b, :c]).should == @set
-    @set.should == Set[:a]
-  end
-
-  it "accepts any enumerable as other" do
-    @set.subtract([:c]).should == Set[:a, :b]
-  end
-end
diff --git a/spec/ruby/library/set/superset_spec.rb b/spec/ruby/library/set/superset_spec.rb
deleted file mode 100644
index bd9d2f3eee..0000000000
--- a/spec/ruby/library/set/superset_spec.rb
+++ /dev/null
@@ -1,41 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'fixtures/set_like'
-require 'set'
-
-describe "Set#superset?" do
-  before :each do
-    @set = Set[1, 2, 3, 4]
-  end
-
-  it "returns true if passed a Set that equals self or self is a proper superset of" do
-    @set.superset?(@set).should be_true
-    Set[].superset?(Set[]).should be_true
-
-    @set.superset?(Set[]).should be_true
-    Set[1, 2, 3].superset?(Set[]).should be_true
-    Set["a", :b, ?c].superset?(Set[]).should be_true
-
-    @set.superset?(Set[1, 2, 3]).should be_true
-    @set.superset?(Set[1, 3]).should be_true
-    @set.superset?(Set[1, 2]).should be_true
-    @set.superset?(Set[1]).should be_true
-
-    @set.superset?(Set[5]).should be_false
-    @set.superset?(Set[1, 5]).should be_false
-    @set.superset?(Set[nil]).should be_false
-    @set.superset?(Set["test"]).should be_false
-  end
-
-  it "raises an ArgumentError when passed a non-Set" do
-    -> { Set[].superset?([]) }.should raise_error(ArgumentError)
-    -> { Set[].superset?(1) }.should raise_error(ArgumentError)
-    -> { Set[].superset?("test") }.should raise_error(ArgumentError)
-    -> { Set[].superset?(Object.new) }.should raise_error(ArgumentError)
-  end
-
-  context "when comparing to a Set-like object" do
-    it "returns true if passed a Set-like object that self is a superset of" do
-      Set[1, 2, 3, 4].superset?(SetSpecs::SetLike.new([1, 2, 3])).should be_true
-    end
-  end
-end
diff --git a/spec/ruby/library/set/to_a_spec.rb b/spec/ruby/library/set/to_a_spec.rb
deleted file mode 100644
index 689e44f38a..0000000000
--- a/spec/ruby/library/set/to_a_spec.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require_relative '../../spec_helper'
-require 'set'
-
-describe "Set#to_a" do
-  it "returns an array containing elements of self" do
-    Set[1, 2, 3].to_a.sort.should == [1, 2, 3]
-  end
-end
diff --git a/spec/ruby/library/set/to_s_spec.rb b/spec/ruby/library/set/to_s_spec.rb
deleted file mode 100644
index ca2806d669..0000000000
--- a/spec/ruby/library/set/to_s_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require_relative 'shared/inspect'
-require 'set'
-
-ruby_version_is "2.5" do
-  describe "Set#to_s" do
-    it_behaves_like :set_inspect, :to_s
-
-    it "is an alias of inspect" do
-      set = Set.new
-      set.method(:to_s).should == set.method(:inspect)
-    end
-  end
-end
diff --git a/spec/ruby/library/set/union_spec.rb b/spec/ruby/library/set/union_spec.rb
deleted file mode 100644
index 20fe0ddca3..0000000000
--- a/spec/ruby/library/set/union_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require_relative '../../spec_helper'
-require_relative 'shared/union'
-require 'set'
-
-describe "Set#union" do
-  it_behaves_like :set_union, :union
-end
-
-describe "Set#|" do
-  it_behaves_like :set_union, :|
-end
diff --git a/spec/ruby/library/shellwords/shellwords_spec.rb b/spec/ruby/library/shellwords/shellwords_spec.rb
index 2975fd9974..d1b61e0a6e 100644
--- a/spec/ruby/library/shellwords/shellwords_spec.rb
+++ b/spec/ruby/library/shellwords/shellwords_spec.rb
@@ -1,34 +1,33 @@
 require_relative '../../spec_helper'
 require 'shellwords'
-include Shellwords
 
 describe "Shellwords#shellwords" do
   it "honors quoted strings" do
-    shellwords('a "b b" a').should == ['a', 'b b', 'a']
+    Shellwords.shellwords('a "b b" a').should == ['a', 'b b', 'a']
   end
 
   it "honors escaped double quotes" do
-    shellwords('a "\"b\" c" d').should == ['a', '"b" c', 'd']
+    Shellwords.shellwords('a "\"b\" c" d').should == ['a', '"b" c', 'd']
   end
 
   it "honors escaped single quotes" do
-    shellwords("a \"'b' c\" d").should == ['a', "'b' c", 'd']
+    Shellwords.shellwords("a \"'b' c\" d").should == ['a', "'b' c", 'd']
   end
 
   it "honors escaped spaces" do
-    shellwords('a b\ c d').should == ['a', 'b c', 'd']
+    Shellwords.shellwords('a b\ c d').should == ['a', 'b c', 'd']
   end
 
   it "raises ArgumentError when double quoted strings are misquoted" do
-    -> { shellwords('a "b c d e') }.should raise_error(ArgumentError)
+    -> { Shellwords.shellwords('a "b c d e') }.should.raise(ArgumentError)
   end
 
   it "raises ArgumentError when single quoted strings are misquoted" do
-    -> { shellwords("a 'b c d e") }.should raise_error(ArgumentError)
+    -> { Shellwords.shellwords("a 'b c d e") }.should.raise(ArgumentError)
   end
 
   # https://bugs.ruby-lang.org/issues/10055
   it "matches POSIX sh behavior for backslashes within double quoted strings" do
-    shellsplit('printf "%s\n"').should == ['printf', '%s\n']
+    Shellwords.shellsplit('printf "%s\n"').should == ['printf', '%s\n']
   end
 end
diff --git a/spec/ruby/library/singleton/allocate_spec.rb b/spec/ruby/library/singleton/allocate_spec.rb
index 6a1512d53b..a0094fb32a 100644
--- a/spec/ruby/library/singleton/allocate_spec.rb
+++ b/spec/ruby/library/singleton/allocate_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "Singleton.allocate" do
   it "is a private method" do
-    -> { SingletonSpecs::MyClass.allocate }.should raise_error(NoMethodError)
+    -> { SingletonSpecs::MyClass.allocate }.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/library/singleton/clone_spec.rb b/spec/ruby/library/singleton/clone_spec.rb
index 3635bcd594..a7b7b731f5 100644
--- a/spec/ruby/library/singleton/clone_spec.rb
+++ b/spec/ruby/library/singleton/clone_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "Singleton#clone" do
   it "is prevented" do
-    -> { SingletonSpecs::MyClass.instance.clone }.should raise_error(TypeError)
+    -> { SingletonSpecs::MyClass.instance.clone }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/singleton/dup_spec.rb b/spec/ruby/library/singleton/dup_spec.rb
index 13d5a213e9..a0455f37b7 100644
--- a/spec/ruby/library/singleton/dup_spec.rb
+++ b/spec/ruby/library/singleton/dup_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "Singleton#dup" do
   it "is prevented" do
-    -> { SingletonSpecs::MyClass.instance.dup }.should raise_error(TypeError)
+    -> { SingletonSpecs::MyClass.instance.dup }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/singleton/instance_spec.rb b/spec/ruby/library/singleton/instance_spec.rb
index 1679728d4c..20cac602b5 100644
--- a/spec/ruby/library/singleton/instance_spec.rb
+++ b/spec/ruby/library/singleton/instance_spec.rb
@@ -3,28 +3,28 @@ require_relative 'fixtures/classes'
 
 describe "Singleton.instance" do
   it "returns an instance of the singleton class" do
-    SingletonSpecs::MyClass.instance.should be_kind_of(SingletonSpecs::MyClass)
+    SingletonSpecs::MyClass.instance.should.is_a?(SingletonSpecs::MyClass)
   end
 
   it "returns the same instance for multiple calls to instance" do
-    SingletonSpecs::MyClass.instance.should equal(SingletonSpecs::MyClass.instance)
+    SingletonSpecs::MyClass.instance.should.equal?(SingletonSpecs::MyClass.instance)
   end
 
   it "returns an instance of the singleton's subclasses" do
-    SingletonSpecs::MyClassChild.instance.should be_kind_of(SingletonSpecs::MyClassChild)
+    SingletonSpecs::MyClassChild.instance.should.is_a?(SingletonSpecs::MyClassChild)
   end
 
   it "returns the same instance for multiple class to instance on subclasses" do
-    SingletonSpecs::MyClassChild.instance.should equal(SingletonSpecs::MyClassChild.instance)
+    SingletonSpecs::MyClassChild.instance.should.equal?(SingletonSpecs::MyClassChild.instance)
   end
 
   it "returns an instance of the singleton's clone" do
     klone = SingletonSpecs::MyClassChild.clone
-    klone.instance.should be_kind_of(klone)
+    klone.instance.should.is_a?(klone)
   end
 
   it "returns the same instance for multiple class to instance on clones" do
     klone = SingletonSpecs::MyClassChild.clone
-    klone.instance.should equal(klone.instance)
+    klone.instance.should.equal?(klone.instance)
   end
 end
diff --git a/spec/ruby/library/singleton/load_spec.rb b/spec/ruby/library/singleton/load_spec.rb
index 4c753f9e7a..ab95d14640 100644
--- a/spec/ruby/library/singleton/load_spec.rb
+++ b/spec/ruby/library/singleton/load_spec.rb
@@ -1,21 +1,20 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-# TODO: change to a.should be_equal(b)
 # TODO: write spec for cloning classes and calling private methods
 # TODO: write spec for private_methods not showing up via extended
 describe "Singleton._load" do
   it "returns the singleton instance for anything passed in" do
     klass = SingletonSpecs::MyClass
-    klass._load("").should equal(klass.instance)
-    klass._load("42").should equal(klass.instance)
-    klass._load(42).should equal(klass.instance)
+    klass._load("").should.equal?(klass.instance)
+    klass._load("42").should.equal?(klass.instance)
+    klass._load(42).should.equal?(klass.instance)
   end
 
   it "returns the singleton instance for anything passed in to subclass" do
     subklass = SingletonSpecs::MyClassChild
-    subklass._load("").should equal(subklass.instance)
-    subklass._load("42").should equal(subklass.instance)
-    subklass._load(42).should equal(subklass.instance)
+    subklass._load("").should.equal?(subklass.instance)
+    subklass._load("42").should.equal?(subklass.instance)
+    subklass._load(42).should.equal?(subklass.instance)
   end
 end
diff --git a/spec/ruby/library/singleton/new_spec.rb b/spec/ruby/library/singleton/new_spec.rb
index 2f45db819c..6167231a29 100644
--- a/spec/ruby/library/singleton/new_spec.rb
+++ b/spec/ruby/library/singleton/new_spec.rb
@@ -3,6 +3,6 @@ require_relative 'fixtures/classes'
 
 describe "Singleton.new" do
   it "is a private method" do
-    -> { SingletonSpecs::NewSpec.new }.should raise_error(NoMethodError)
+    -> { SingletonSpecs::NewSpec.new }.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/afamily_spec.rb b/spec/ruby/library/socket/addrinfo/afamily_spec.rb
index 7229dab9de..5d075be057 100644
--- a/spec/ruby/library/socket/addrinfo/afamily_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/afamily_spec.rb
@@ -23,15 +23,13 @@ describe "Addrinfo#afamily" do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
-
-      it "returns Socket::AF_UNIX" do
-        @addrinfo.afamily.should == Socket::AF_UNIX
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
+
+    it "returns Socket::AF_UNIX" do
+      @addrinfo.afamily.should == Socket::AF_UNIX
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/bind_spec.rb b/spec/ruby/library/socket/addrinfo/bind_spec.rb
index 6f78890a4d..cdd187771f 100644
--- a/spec/ruby/library/socket/addrinfo/bind_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/bind_spec.rb
@@ -13,16 +13,16 @@ describe "Addrinfo#bind" do
 
   it "returns a bound socket when no block is given" do
     @socket = @addrinfo.bind
-    @socket.should be_kind_of(Socket)
-    @socket.closed?.should be_false
+    @socket.should.is_a?(Socket)
+    @socket.closed?.should == false
   end
 
   it "yields the socket if a block is given" do
     @addrinfo.bind do |sock|
       @socket = sock
-      sock.should be_kind_of(Socket)
+      sock.should.is_a?(Socket)
     end
-    @socket.closed?.should be_true
+    @socket.closed?.should == true
   end
 
 end
diff --git a/spec/ruby/library/socket/addrinfo/canonname_spec.rb b/spec/ruby/library/socket/addrinfo/canonname_spec.rb
index a1cc8b3980..efd3147125 100644
--- a/spec/ruby/library/socket/addrinfo/canonname_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/canonname_spec.rb
@@ -10,7 +10,7 @@ describe "Addrinfo#canonname" do
   it "returns the canonical name for a host" do
     canonname = @addrinfos.map { |a| a.canonname }.find { |name| name and name.include?("localhost") }
     if canonname
-      canonname.should include("localhost")
+      canonname.should.include?("localhost")
     else
       canonname.should == nil
     end
@@ -20,7 +20,7 @@ describe "Addrinfo#canonname" do
     it 'returns nil' do
       addr = Addrinfo.new(Socket.sockaddr_in(0, '127.0.0.1'))
 
-      addr.canonname.should be_nil
+      addr.canonname.should == nil
     end
   end
 
diff --git a/spec/ruby/library/socket/addrinfo/connect_from_spec.rb b/spec/ruby/library/socket/addrinfo/connect_from_spec.rb
index 55fce2e159..b1f6caa174 100644
--- a/spec/ruby/library/socket/addrinfo/connect_from_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/connect_from_spec.rb
@@ -17,18 +17,18 @@ describe 'Addrinfo#connect_from' do
     describe 'using separate arguments' do
       it 'returns a Socket when no block is given' do
         @socket = @addr.connect_from(ip_address, 0)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'yields the Socket when a block is given' do
         @addr.connect_from(ip_address, 0) do |socket|
-          socket.should be_an_instance_of(Socket)
+          socket.should.instance_of?(Socket)
         end
       end
 
       it 'treats the last argument as a set of options if it is a Hash' do
         @socket = @addr.connect_from(ip_address, 0, timeout: 2)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'binds the socket to the local address' do
@@ -48,18 +48,18 @@ describe 'Addrinfo#connect_from' do
 
       it 'returns a Socket when no block is given' do
         @socket = @addr.connect_from(@from_addr)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'yields the Socket when a block is given' do
         @addr.connect_from(@from_addr) do |socket|
-          socket.should be_an_instance_of(Socket)
+          socket.should.instance_of?(Socket)
         end
       end
 
       it 'treats the last argument as a set of options if it is a Hash' do
         @socket = @addr.connect_from(@from_addr, timeout: 2)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'binds the socket to the local address' do
diff --git a/spec/ruby/library/socket/addrinfo/connect_spec.rb b/spec/ruby/library/socket/addrinfo/connect_spec.rb
index 1c2dc609ca..a8494b5501 100644
--- a/spec/ruby/library/socket/addrinfo/connect_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/connect_spec.rb
@@ -16,20 +16,20 @@ describe 'Addrinfo#connect' do
     it 'returns a Socket when no block is given' do
       addr = Addrinfo.tcp(ip_address, @port)
       @socket = addr.connect
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
 
     it 'yields a Socket when a block is given' do
       addr = Addrinfo.tcp(ip_address, @port)
       addr.connect do |socket|
-        socket.should be_an_instance_of(Socket)
+        socket.should.instance_of?(Socket)
       end
     end
 
     it 'accepts a Hash of options' do
       addr = Addrinfo.tcp(ip_address, @port)
       @socket = addr.connect(timeout: 2)
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/connect_to_spec.rb b/spec/ruby/library/socket/addrinfo/connect_to_spec.rb
index 69666da19b..2bf49a38e8 100644
--- a/spec/ruby/library/socket/addrinfo/connect_to_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/connect_to_spec.rb
@@ -17,18 +17,18 @@ describe 'Addrinfo#connect_to' do
     describe 'using separate arguments' do
       it 'returns a Socket when no block is given' do
         @socket = @addr.connect_to(ip_address, @port)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'yields the Socket when a block is given' do
         @addr.connect_to(ip_address, @port) do |socket|
-          socket.should be_an_instance_of(Socket)
+          socket.should.instance_of?(Socket)
         end
       end
 
       it 'treats the last argument as a set of options if it is a Hash' do
         @socket = @addr.connect_to(ip_address, @port, timeout: 2)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'binds the Addrinfo to the local address' do
@@ -48,18 +48,18 @@ describe 'Addrinfo#connect_to' do
 
       it 'returns a Socket when no block is given' do
         @socket = @addr.connect_to(@to_addr)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'yields the Socket when a block is given' do
         @addr.connect_to(@to_addr) do |socket|
-          socket.should be_an_instance_of(Socket)
+          socket.should.instance_of?(Socket)
         end
       end
 
       it 'treats the last argument as a set of options if it is a Hash' do
         @socket = @addr.connect_to(@to_addr, timeout: 2)
-        @socket.should be_an_instance_of(Socket)
+        @socket.should.instance_of?(Socket)
       end
 
       it 'binds the socket to the local address' do
diff --git a/spec/ruby/library/socket/addrinfo/family_addrinfo_spec.rb b/spec/ruby/library/socket/addrinfo/family_addrinfo_spec.rb
index 2bc3b6a2e3..38834ade91 100644
--- a/spec/ruby/library/socket/addrinfo/family_addrinfo_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/family_addrinfo_spec.rb
@@ -4,7 +4,7 @@ describe 'Addrinfo#family_addrinfo' do
   it 'raises ArgumentError if no arguments are given' do
     addr = Addrinfo.tcp('127.0.0.1', 0)
 
-    -> { addr.family_addrinfo }.should raise_error(ArgumentError)
+    -> { addr.family_addrinfo }.should.raise(ArgumentError)
   end
 
   describe 'using multiple arguments' do
@@ -14,17 +14,17 @@ describe 'Addrinfo#family_addrinfo' do
       end
 
       it 'raises ArgumentError if only 1 argument is given' do
-        -> { @source.family_addrinfo('127.0.0.1') }.should raise_error(ArgumentError)
+        -> { @source.family_addrinfo('127.0.0.1') }.should.raise(ArgumentError)
       end
 
       it 'raises ArgumentError if more than 2 arguments are given' do
-        -> { @source.family_addrinfo('127.0.0.1', 0, 666) }.should raise_error(ArgumentError)
+        -> { @source.family_addrinfo('127.0.0.1', 0, 666) }.should.raise(ArgumentError)
       end
 
       it 'returns an Addrinfo when a host and port are given' do
         addr = @source.family_addrinfo('127.0.0.1', 0)
 
-        addr.should be_an_instance_of(Addrinfo)
+        addr.should.instance_of?(Addrinfo)
       end
 
       describe 'the returned Addrinfo' do
@@ -50,38 +50,36 @@ describe 'Addrinfo#family_addrinfo' do
       end
     end
 
-    with_feature :unix_socket do
-      describe 'with a UNIX Addrinfo' do
-        before do
-          @source = Addrinfo.unix('cats')
-        end
+    describe 'with a UNIX Addrinfo' do
+      before do
+        @source = Addrinfo.unix('cats')
+      end
 
-        it 'raises ArgumentError if more than 1 argument is given' do
-          -> { @source.family_addrinfo('foo', 'bar') }.should raise_error(ArgumentError)
-        end
+      it 'raises ArgumentError if more than 1 argument is given' do
+        -> { @source.family_addrinfo('foo', 'bar') }.should.raise(ArgumentError)
+      end
 
-        it 'returns an Addrinfo when a UNIX socket path is given' do
-          addr = @source.family_addrinfo('dogs')
+      it 'returns an Addrinfo when a UNIX socket path is given' do
+        addr = @source.family_addrinfo('dogs')
 
-          addr.should be_an_instance_of(Addrinfo)
-        end
+        addr.should.instance_of?(Addrinfo)
+      end
 
-        describe 'the returned Addrinfo' do
-          before do
-            @addr = @source.family_addrinfo('dogs')
-          end
+      describe 'the returned Addrinfo' do
+        before do
+          @addr = @source.family_addrinfo('dogs')
+        end
 
-          it 'uses AF_UNIX as the address family' do
-            @addr.afamily.should == Socket::AF_UNIX
-          end
+        it 'uses AF_UNIX as the address family' do
+          @addr.afamily.should == Socket::AF_UNIX
+        end
 
-          it 'uses PF_UNIX as the protocol family' do
-            @addr.pfamily.should == Socket::PF_UNIX
-          end
+        it 'uses PF_UNIX as the protocol family' do
+          @addr.pfamily.should == Socket::PF_UNIX
+        end
 
-          it 'uses the given socket path' do
-            @addr.unix_path.should == 'dogs'
-          end
+        it 'uses the given socket path' do
+          @addr.unix_path.should == 'dogs'
         end
       end
     end
@@ -99,17 +97,17 @@ describe 'Addrinfo#family_addrinfo' do
 
     it 'raises ArgumentError if more than 1 argument is given' do
       input = Addrinfo.tcp('127.0.0.2', 0)
-      -> { @source.family_addrinfo(input, 666) }.should raise_error(ArgumentError)
+      -> { @source.family_addrinfo(input, 666) }.should.raise(ArgumentError)
     end
 
     it "raises ArgumentError if the protocol families don't match" do
       input = Addrinfo.tcp('::1', 0)
-      -> { @source.family_addrinfo(input) }.should raise_error(ArgumentError)
+      -> { @source.family_addrinfo(input) }.should.raise(ArgumentError)
     end
 
     it "raises ArgumentError if the socket types don't match" do
       input = Addrinfo.udp('127.0.0.1', 0)
-      -> { @source.family_addrinfo(input) }.should raise_error(ArgumentError)
+      -> { @source.family_addrinfo(input) }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/foreach_spec.rb b/spec/ruby/library/socket/addrinfo/foreach_spec.rb
index 6ec8fab905..8cbbddb8f0 100644
--- a/spec/ruby/library/socket/addrinfo/foreach_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/foreach_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 describe 'Addrinfo.foreach' do
   it 'yields Addrinfo instances to the supplied block' do
     Addrinfo.foreach('127.0.0.1', 80) do |addr|
-      addr.should be_an_instance_of(Addrinfo)
+      addr.should.instance_of?(Addrinfo)
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/getaddrinfo_spec.rb b/spec/ruby/library/socket/addrinfo/getaddrinfo_spec.rb
index 67fad73815..47393ee167 100644
--- a/spec/ruby/library/socket/addrinfo/getaddrinfo_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/getaddrinfo_spec.rb
@@ -5,8 +5,8 @@ describe 'Addrinfo.getaddrinfo' do
   it 'returns an Array of Addrinfo instances' do
     array = Addrinfo.getaddrinfo('127.0.0.1', 80)
 
-    array.should be_an_instance_of(Array)
-    array[0].should be_an_instance_of(Addrinfo)
+    array.should.instance_of?(Array)
+    array[0].should.instance_of?(Addrinfo)
   end
 
   SocketSpecs.each_ip_protocol do |family, ip_address|
@@ -54,7 +54,7 @@ describe 'Addrinfo.getaddrinfo' do
       array    = Addrinfo.getaddrinfo('127.0.0.1', 80)
       possible = [Socket::SOCK_STREAM, Socket::SOCK_DGRAM]
 
-      possible.should include(array[0].socktype)
+      possible.should.include?(array[0].socktype)
     end
   end
 
@@ -69,23 +69,19 @@ describe 'Addrinfo.getaddrinfo' do
       array    = Addrinfo.getaddrinfo('127.0.0.1', 80)
       possible = [Socket::IPPROTO_TCP, Socket::IPPROTO_UDP]
 
-      possible.should include(array[0].protocol)
+      possible.should.include?(array[0].protocol)
     end
   end
 
-  platform_is_not :'solaris2.10' do # i386-solaris
-    it 'sets a custom socket protocol of the Addrinfo instances' do
-      array = Addrinfo.getaddrinfo('127.0.0.1', 80, nil, nil, Socket::IPPROTO_UDP)
+  it 'sets a custom socket protocol of the Addrinfo instances' do
+    array = Addrinfo.getaddrinfo('127.0.0.1', 80, nil, nil, Socket::IPPROTO_UDP)
 
-      array[0].protocol.should == Socket::IPPROTO_UDP
-    end
+    array[0].protocol.should == Socket::IPPROTO_UDP
   end
 
-  platform_is_not :solaris do
-    it 'sets the canonical name when AI_CANONNAME is given as a flag' do
-      array = Addrinfo.getaddrinfo('localhost', 80, nil, nil, nil, Socket::AI_CANONNAME)
+  it 'sets the canonical name when AI_CANONNAME is given as a flag' do
+    array = Addrinfo.getaddrinfo('localhost', 80, nil, nil, nil, Socket::AI_CANONNAME)
 
-      array[0].canonname.should be_an_instance_of(String)
-    end
+    array[0].canonname.should.instance_of?(String)
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/getnameinfo_spec.rb b/spec/ruby/library/socket/addrinfo/getnameinfo_spec.rb
index c5284f1c0f..43b5a2000a 100644
--- a/spec/ruby/library/socket/addrinfo/getnameinfo_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/getnameinfo_spec.rb
@@ -21,7 +21,7 @@ describe 'Addrinfo#getnameinfo' do
   end
 
   platform_is :linux do
-    with_feature :unix_socket do
+    platform_is_not :android do
       describe 'using a UNIX Addrinfo' do
         before do
           @addr = Addrinfo.unix('cats')
diff --git a/spec/ruby/library/socket/addrinfo/initialize_spec.rb b/spec/ruby/library/socket/addrinfo/initialize_spec.rb
index 8354553f61..f33255e38b 100644
--- a/spec/ruby/library/socket/addrinfo/initialize_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/initialize_spec.rb
@@ -17,7 +17,7 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 25
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the UNSPEC pfamily" do
         @addrinfo.pfamily.should == Socket::PF_UNSPEC
       end
 
@@ -53,11 +53,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 25
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET6
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET6
       end
 
@@ -83,15 +83,15 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 25
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET6
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET6
       end
 
-      it "returns the 0 socket type" do
+      it "returns the specified socket type" do
         @addrinfo.socktype.should == Socket::SOCK_STREAM
       end
 
@@ -113,11 +113,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 25
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET6
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET6
       end
 
@@ -147,11 +147,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 46102
       end
 
-      it "returns the Socket::PF_INET pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET
       end
 
@@ -200,7 +200,7 @@ describe "Addrinfo#initialize" do
       it 'raises SocketError' do
         block = -> { Addrinfo.new(['AF_INET6', 80, 'hostname', '127.0.0.1']) }
 
-        block.should raise_error(SocketError)
+        block.should.raise(SocketError)
       end
     end
 
@@ -217,11 +217,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 46102
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET
       end
 
@@ -247,11 +247,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 46102
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET
       end
 
@@ -274,15 +274,17 @@ describe "Addrinfo#initialize" do
         end
       end
 
-      with_feature :sock_packet do
-        [:SOCK_SEQPACKET].each do |type|
-          it "overwrites the socket type #{type}" do
-            sockaddr = ['AF_INET', 80, 'hostname', '127.0.0.1']
+      platform_is_not :android do
+        with_feature :sock_packet do
+          [:SOCK_SEQPACKET].each do |type|
+            it "overwrites the socket type #{type}" do
+              sockaddr = ['AF_INET', 80, 'hostname', '127.0.0.1']
 
-            value = Socket.const_get(type)
-            addr  = Addrinfo.new(sockaddr, nil, value)
+              value = Socket.const_get(type)
+              addr  = Addrinfo.new(sockaddr, nil, value)
 
-            addr.socktype.should == value
+              addr.socktype.should == value
+            end
           end
         end
       end
@@ -292,7 +294,7 @@ describe "Addrinfo#initialize" do
         value = Socket::SOCK_RDM
         block = -> { Addrinfo.new(sockaddr, nil, value) }
 
-        block.should raise_error(SocketError)
+        block.should.raise(SocketError)
       end
     end
 
@@ -309,11 +311,11 @@ describe "Addrinfo#initialize" do
         @addrinfo.ip_port.should == 46102
       end
 
-      it "returns the Socket::UNSPEC pfamily" do
+      it "returns the specified pfamily" do
         @addrinfo.pfamily.should == Socket::PF_INET
       end
 
-      it "returns the INET6 afamily" do
+      it "returns the specified afamily" do
         @addrinfo.afamily.should == Socket::AF_INET
       end
 
@@ -333,12 +335,12 @@ describe "Addrinfo#initialize" do
         @sockaddr = ['AF_INET6', 80, 'hostname', '127.0.0.1']
       end
 
-      it "raises SocketError when using any Socket constant except except AF_INET(6)/PF_INET(6)" do
+      it "raises SocketError when using any Socket constant except AF_INET(6)/PF_INET(6)" do
         Socket.constants.grep(/(^AF_|^PF_)(?!INET)/).each do |constant|
           value = Socket.const_get(constant)
           -> {
             Addrinfo.new(@sockaddr, value)
-          }.should raise_error(SocketError)
+          }.should.raise(SocketError)
         end
       end
     end
@@ -360,13 +362,13 @@ describe "Addrinfo#initialize" do
           end
         end
 
-        platform_is_not :windows, :aix, :solaris do
+        platform_is_not :windows, :aix do
           (Socket.constants.grep(/^IPPROTO/) - valid).each do |type|
             it "raises SocketError when using #{type}" do
               value = Socket.const_get(type)
               block = -> { Addrinfo.new(@sockaddr, nil, nil, value) }
 
-              block.should raise_error(SocketError)
+              block.should.raise(SocketError)
             end
           end
         end
@@ -388,13 +390,13 @@ describe "Addrinfo#initialize" do
           end
         end
 
-        platform_is_not :windows, :aix, :solaris do
+        platform_is_not :windows, :aix do
           (Socket.constants.grep(/^IPPROTO/) - valid).each do |type|
             it "raises SocketError when using #{type}" do
               value = Socket.const_get(type)
               block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
 
-              block.should raise_error(SocketError)
+              block.should.raise(SocketError)
             end
           end
         end
@@ -411,7 +413,7 @@ describe "Addrinfo#initialize" do
               value = Socket.const_get(type)
               block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
 
-              block.should raise_error(SocketError)
+              block.should.raise(SocketError)
             end
           end
         end
@@ -442,34 +444,36 @@ describe "Addrinfo#initialize" do
             value = Socket.const_get(type)
             block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
 
-            block.should raise_error(SocketError)
+            block.should.raise(SocketError)
           end
         end
       end
 
       platform_is :linux do
-        describe 'and the socket type is set to SOCK_SEQPACKET' do
-          before do
-            @socktype = Socket::SOCK_SEQPACKET
-          end
+        platform_is_not :android do
+          describe 'and the socket type is set to SOCK_SEQPACKET' do
+            before do
+              @socktype = Socket::SOCK_SEQPACKET
+            end
 
-          valid = [:IPPROTO_IP, :IPPROTO_HOPOPTS]
+            valid = [:IPPROTO_IP, :IPPROTO_HOPOPTS]
 
-          valid.each do |type|
-            it "overwrites the protocol when using #{type}" do
-              value = Socket.const_get(type)
-              addr  = Addrinfo.new(@sockaddr, nil, @socktype, value)
+            valid.each do |type|
+              it "overwrites the protocol when using #{type}" do
+                value = Socket.const_get(type)
+                addr  = Addrinfo.new(@sockaddr, nil, @socktype, value)
 
-              addr.protocol.should == value
+                addr.protocol.should == value
+              end
             end
-          end
 
-          (Socket.constants.grep(/^IPPROTO/) - valid).each do |type|
-            it "raises SocketError when using #{type}" do
-              value = Socket.const_get(type)
-              block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
+            (Socket.constants.grep(/^IPPROTO/) - valid).each do |type|
+              it "raises SocketError when using #{type}" do
+                value = Socket.const_get(type)
+                block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
 
-              block.should raise_error(SocketError)
+                block.should.raise(SocketError)
+              end
             end
           end
         end
@@ -491,13 +495,13 @@ describe "Addrinfo#initialize" do
           end
         end
 
-        platform_is_not :windows, :aix, :solaris do
+        platform_is_not :windows, :aix do
           (Socket.constants.grep(/^IPPROTO/) - valid).each do |type|
             it "raises SocketError when using #{type}" do
               value = Socket.const_get(type)
               block = -> { Addrinfo.new(@sockaddr, nil, @socktype, value) }
 
-              block.should raise_error(SocketError)
+              block.should.raise(SocketError)
             end
           end
         end
@@ -510,13 +514,13 @@ describe "Addrinfo#initialize" do
       @sockaddr = Socket.sockaddr_in(80, '127.0.0.1')
     end
 
-    it 'returns an Addrinfo with :PF_INET  family' do
+    it 'returns an Addrinfo with the specified pfamily for :PF_INET' do
       addr = Addrinfo.new(@sockaddr, :PF_INET)
 
       addr.pfamily.should == Socket::PF_INET
     end
 
-    it 'returns an Addrinfo with :INET  family' do
+    it 'returns an Addrinfo with the specified pfamily for :INET' do
       addr = Addrinfo.new(@sockaddr, :INET)
 
       addr.pfamily.should == Socket::PF_INET
@@ -540,13 +544,13 @@ describe "Addrinfo#initialize" do
       @sockaddr = Socket.sockaddr_in(80, '127.0.0.1')
     end
 
-    it 'returns an Addrinfo with "PF_INET"  family' do
+    it 'returns an Addrinfo with the specified pfamily for PF_INET' do
       addr = Addrinfo.new(@sockaddr, 'PF_INET')
 
       addr.pfamily.should == Socket::PF_INET
     end
 
-    it 'returns an Addrinfo with "INET"  family' do
+    it 'returns an Addrinfo with the specified pfamily for INET' do
       addr = Addrinfo.new(@sockaddr, 'INET')
 
       addr.pfamily.should == Socket::PF_INET
@@ -565,23 +569,21 @@ describe "Addrinfo#initialize" do
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using separate arguments for a Unix socket' do
-      before do
-        @sockaddr = Socket.pack_sockaddr_un('socket')
-      end
+  describe 'using separate arguments for a Unix socket' do
+    before do
+      @sockaddr = Socket.pack_sockaddr_un('socket')
+    end
 
-      it 'returns an Addrinfo with the correct unix path' do
-        Addrinfo.new(@sockaddr).unix_path.should == 'socket'
-      end
+    it 'returns an Addrinfo with the correct unix path' do
+      Addrinfo.new(@sockaddr).unix_path.should == 'socket'
+    end
 
-      it 'returns an Addrinfo with the correct protocol family' do
-        Addrinfo.new(@sockaddr).pfamily.should == Socket::PF_UNSPEC
-      end
+    it 'returns an Addrinfo with the correct protocol family' do
+      Addrinfo.new(@sockaddr).pfamily.should == Socket::PF_UNSPEC
+    end
 
-      it 'returns an Addrinfo with the correct address family' do
-        Addrinfo.new(@sockaddr).afamily.should == Socket::AF_UNIX
-      end
+    it 'returns an Addrinfo with the correct address family' do
+      Addrinfo.new(@sockaddr).afamily.should == Socket::AF_UNIX
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/inspect_sockaddr_spec.rb b/spec/ruby/library/socket/addrinfo/inspect_sockaddr_spec.rb
index 70ca4dd4d7..6b18c79469 100644
--- a/spec/ruby/library/socket/addrinfo/inspect_sockaddr_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/inspect_sockaddr_spec.rb
@@ -32,19 +32,17 @@ describe 'Addrinfo#inspect_sockaddr' do
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using a UNIX path' do
-      it 'returns a String containing the UNIX path' do
-        addr = Addrinfo.unix('/foo/bar')
+  describe 'using a UNIX path' do
+    it 'returns a String containing the UNIX path' do
+      addr = Addrinfo.unix('/foo/bar')
 
-        addr.inspect_sockaddr.should == '/foo/bar'
-      end
+      addr.inspect_sockaddr.should == '/foo/bar'
+    end
 
-      it 'returns a String containing the UNIX path when using a relative path' do
-        addr = Addrinfo.unix('foo')
+    it 'returns a String containing the UNIX path when using a relative path' do
+      addr = Addrinfo.unix('foo')
 
-        addr.inspect_sockaddr.should == 'UNIX foo'
-      end
+      addr.inspect_sockaddr.should == 'UNIX foo'
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/inspect_spec.rb b/spec/ruby/library/socket/addrinfo/inspect_spec.rb
index 98e1e83ffa..1442af6162 100644
--- a/spec/ruby/library/socket/addrinfo/inspect_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/inspect_spec.rb
@@ -41,25 +41,23 @@ describe 'Addrinfo#inspect' do
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using a UNIX Addrinfo' do
-      it 'returns a String' do
-        addr = Addrinfo.unix('/foo')
+  describe 'using a UNIX Addrinfo' do
+    it 'returns a String' do
+      addr = Addrinfo.unix('/foo')
 
-        addr.inspect.should == '#<Addrinfo: /foo SOCK_STREAM>'
-      end
+      addr.inspect.should == '#<Addrinfo: /foo SOCK_STREAM>'
+    end
 
-      it 'returns a String when using a relative UNIX path' do
-        addr = Addrinfo.unix('foo')
+    it 'returns a String when using a relative UNIX path' do
+      addr = Addrinfo.unix('foo')
 
-        addr.inspect.should == '#<Addrinfo: UNIX foo SOCK_STREAM>'
-      end
+      addr.inspect.should == '#<Addrinfo: UNIX foo SOCK_STREAM>'
+    end
 
-      it 'returns a String when using a DGRAM socket' do
-        addr = Addrinfo.unix('/foo', Socket::SOCK_DGRAM)
+    it 'returns a String when using a DGRAM socket' do
+      addr = Addrinfo.unix('/foo', Socket::SOCK_DGRAM)
 
-        addr.inspect.should == '#<Addrinfo: /foo SOCK_DGRAM>'
-      end
+      addr.inspect.should == '#<Addrinfo: /foo SOCK_DGRAM>'
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ip_address_spec.rb b/spec/ruby/library/socket/addrinfo/ip_address_spec.rb
index 4522cf5cfd..9a0ede4eeb 100644
--- a/spec/ruby/library/socket/addrinfo/ip_address_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ip_address_spec.rb
@@ -21,15 +21,13 @@ describe "Addrinfo#ip_address" do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "raises an exception" do
-        -> { @addrinfo.ip_address }.should raise_error(SocketError)
-      end
+    it "raises an exception" do
+      -> { @addrinfo.ip_address }.should.raise(SocketError)
     end
   end
 
diff --git a/spec/ruby/library/socket/addrinfo/ip_port_spec.rb b/spec/ruby/library/socket/addrinfo/ip_port_spec.rb
index 4118607db0..00f74cdd46 100644
--- a/spec/ruby/library/socket/addrinfo/ip_port_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ip_port_spec.rb
@@ -21,15 +21,13 @@ describe "Addrinfo#ip_port" do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "raises an exception" do
-        -> { @addrinfo.ip_port }.should raise_error(SocketError)
-      end
+    it "raises an exception" do
+      -> { @addrinfo.ip_port }.should.raise(SocketError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ip_spec.rb b/spec/ruby/library/socket/addrinfo/ip_spec.rb
index 80e7a62df7..2237eca263 100644
--- a/spec/ruby/library/socket/addrinfo/ip_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ip_spec.rb
@@ -8,7 +8,7 @@ describe "Addrinfo#ip?" do
     end
 
     it "returns true" do
-      @addrinfo.ip?.should be_true
+      @addrinfo.ip?.should == true
     end
   end
 
@@ -18,19 +18,17 @@ describe "Addrinfo#ip?" do
     end
 
     it "returns true" do
-      @addrinfo.ip?.should be_true
+      @addrinfo.ip?.should == true
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ip?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ip?.should == false
     end
   end
 end
@@ -38,7 +36,7 @@ end
 describe 'Addrinfo.ip' do
   SocketSpecs.each_ip_protocol do |family, ip_address|
     it 'returns an Addrinfo instance' do
-      Addrinfo.ip(ip_address).should be_an_instance_of(Addrinfo)
+      Addrinfo.ip(ip_address).should.instance_of?(Addrinfo)
     end
 
     it 'sets the IP address' do
diff --git a/spec/ruby/library/socket/addrinfo/ip_unpack_spec.rb b/spec/ruby/library/socket/addrinfo/ip_unpack_spec.rb
index 6c81c48d1c..b48ca062ee 100644
--- a/spec/ruby/library/socket/addrinfo/ip_unpack_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ip_unpack_spec.rb
@@ -21,15 +21,13 @@ describe "Addrinfo#ip_unpack" do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "raises an exception" do
-        -> { @addrinfo.ip_unpack }.should raise_error(SocketError)
-      end
+    it "raises an exception" do
+      -> { @addrinfo.ip_unpack }.should.raise(SocketError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv4_loopback_spec.rb b/spec/ruby/library/socket/addrinfo/ipv4_loopback_spec.rb
index f5bab711db..266281ce7a 100644
--- a/spec/ruby/library/socket/addrinfo/ipv4_loopback_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv4_loopback_spec.rb
@@ -3,14 +3,14 @@ require_relative '../spec_helper'
 describe "Addrinfo#ipv4_loopback?" do
   describe "for an ipv4 socket" do
     it "returns true for the loopback address" do
-      Addrinfo.ip('127.0.0.1').ipv4_loopback?.should == true
-      Addrinfo.ip('127.0.0.2').ipv4_loopback?.should == true
-      Addrinfo.ip('127.255.0.1').ipv4_loopback?.should == true
-      Addrinfo.ip('127.255.255.255').ipv4_loopback?.should == true
+      Addrinfo.ip('127.0.0.1').should.ipv4_loopback?
+      Addrinfo.ip('127.0.0.2').should.ipv4_loopback?
+      Addrinfo.ip('127.255.0.1').should.ipv4_loopback?
+      Addrinfo.ip('127.255.255.255').should.ipv4_loopback?
     end
 
     it "returns false for another address" do
-      Addrinfo.ip('255.255.255.0').ipv4_loopback?.should be_false
+      Addrinfo.ip('255.255.255.0').ipv4_loopback?.should == false
     end
   end
 
@@ -21,23 +21,21 @@ describe "Addrinfo#ipv4_loopback?" do
     end
 
     it "returns false for the loopback address" do
-      @loopback.ipv4_loopback?.should be_false
+      @loopback.ipv4_loopback?.should == false
     end
 
     it "returns false for another address" do
-      @other.ipv4_loopback?.should be_false
+      @other.ipv4_loopback?.should == false
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv4_loopback?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv4_loopback?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv4_multicast_spec.rb b/spec/ruby/library/socket/addrinfo/ipv4_multicast_spec.rb
index bdd14c1b00..bc8a31dfa8 100644
--- a/spec/ruby/library/socket/addrinfo/ipv4_multicast_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv4_multicast_spec.rb
@@ -2,28 +2,26 @@ require_relative '../spec_helper'
 
 describe "Addrinfo#ipv4_multicast?" do
   it 'returns true for a multicast address' do
-    Addrinfo.ip('224.0.0.0').ipv4_multicast?.should == true
-    Addrinfo.ip('224.0.0.9').ipv4_multicast?.should == true
-    Addrinfo.ip('239.255.255.250').ipv4_multicast?.should == true
+    Addrinfo.ip('224.0.0.0').should.ipv4_multicast?
+    Addrinfo.ip('224.0.0.9').should.ipv4_multicast?
+    Addrinfo.ip('239.255.255.250').should.ipv4_multicast?
   end
 
   it 'returns false for a regular address' do
-    Addrinfo.ip('8.8.8.8').ipv4_multicast?.should == false
+    Addrinfo.ip('8.8.8.8').should_not.ipv4_multicast?
   end
 
   it 'returns false for an IPv6 address' do
-    Addrinfo.ip('::1').ipv4_multicast?.should == false
+    Addrinfo.ip('::1').should_not.ipv4_multicast?
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv4_multicast?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv4_multicast?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv4_private_spec.rb b/spec/ruby/library/socket/addrinfo/ipv4_private_spec.rb
index 733577609e..8cfbf0a25e 100644
--- a/spec/ruby/library/socket/addrinfo/ipv4_private_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv4_private_spec.rb
@@ -8,18 +8,18 @@ describe "Addrinfo#ipv4_private?" do
     end
 
     it "returns true for a private address" do
-      Addrinfo.ip('10.0.0.0').ipv4_private?.should == true
-      Addrinfo.ip('10.0.0.5').ipv4_private?.should == true
+      Addrinfo.ip('10.0.0.0').should.ipv4_private?
+      Addrinfo.ip('10.0.0.5').should.ipv4_private?
 
-      Addrinfo.ip('172.16.0.0').ipv4_private?.should == true
-      Addrinfo.ip('172.16.0.5').ipv4_private?.should == true
+      Addrinfo.ip('172.16.0.0').should.ipv4_private?
+      Addrinfo.ip('172.16.0.5').should.ipv4_private?
 
-      Addrinfo.ip('192.168.0.0').ipv4_private?.should == true
-      Addrinfo.ip('192.168.0.5').ipv4_private?.should == true
+      Addrinfo.ip('192.168.0.0').should.ipv4_private?
+      Addrinfo.ip('192.168.0.5').should.ipv4_private?
     end
 
     it "returns false for a public address" do
-      @other.ipv4_private?.should be_false
+      @other.ipv4_private?.should == false
     end
   end
 
@@ -29,19 +29,17 @@ describe "Addrinfo#ipv4_private?" do
     end
 
     it "returns false" do
-      @other.ipv4_private?.should be_false
+      @other.ipv4_private?.should == false
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv4_private?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv4_private?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv4_spec.rb b/spec/ruby/library/socket/addrinfo/ipv4_spec.rb
index 7cba8209b6..8fef94a8e8 100644
--- a/spec/ruby/library/socket/addrinfo/ipv4_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv4_spec.rb
@@ -7,7 +7,7 @@ describe "Addrinfo#ipv4?" do
     end
 
     it "returns true" do
-      @addrinfo.ipv4?.should be_true
+      @addrinfo.ipv4?.should == true
     end
   end
 
@@ -17,19 +17,17 @@ describe "Addrinfo#ipv4?" do
     end
 
     it "returns false" do
-      @addrinfo.ipv4?.should be_false
+      @addrinfo.ipv4?.should == false
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv4?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv4?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_linklocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_linklocal_spec.rb
index 291b4d7d6b..bfef396381 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_linklocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_linklocal_spec.rb
@@ -5,19 +5,19 @@ guard -> { SocketSpecs.ipv6_available? } do
   describe 'Addrinfo#ipv6_linklocal?' do
     platform_is_not :aix do
       it 'returns true for a link-local address' do
-        Addrinfo.ip('fe80::').ipv6_linklocal?.should == true
-        Addrinfo.ip('fe81::').ipv6_linklocal?.should == true
-        Addrinfo.ip('fe8f::').ipv6_linklocal?.should == true
-        Addrinfo.ip('fe80::1').ipv6_linklocal?.should == true
+        Addrinfo.ip('fe80::').should.ipv6_linklocal?
+        Addrinfo.ip('fe81::').should.ipv6_linklocal?
+        Addrinfo.ip('fe8f::').should.ipv6_linklocal?
+        Addrinfo.ip('fe80::1').should.ipv6_linklocal?
       end
     end
 
     it 'returns false for a regular address' do
-      Addrinfo.ip('::1').ipv6_linklocal?.should == false
+      Addrinfo.ip('::1').should_not.ipv6_linklocal?
     end
 
     it 'returns false for an IPv4 address' do
-      Addrinfo.ip('127.0.0.1').ipv6_linklocal?.should == false
+      Addrinfo.ip('127.0.0.1').should_not.ipv6_linklocal?
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_loopback_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_loopback_spec.rb
index 9ff8f107bf..2e8241e336 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_loopback_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_loopback_spec.rb
@@ -8,11 +8,11 @@ describe "Addrinfo#ipv6_loopback?" do
     end
 
     it "returns false for the loopback address" do
-      @loopback.ipv6_loopback?.should be_false
+      @loopback.ipv6_loopback?.should == false
     end
 
     it "returns false for another address" do
-      @other.ipv6_loopback?.should be_false
+      @other.ipv6_loopback?.should == false
     end
   end
 
@@ -23,23 +23,21 @@ describe "Addrinfo#ipv6_loopback?" do
     end
 
     it "returns true for the loopback address" do
-      @loopback.ipv6_loopback?.should be_true
+      @loopback.ipv6_loopback?.should == true
     end
 
     it "returns false for another address" do
-      @other.ipv6_loopback?.should be_false
+      @other.ipv6_loopback?.should == false
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv6_loopback?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv6_loopback?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_mc_global_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_mc_global_spec.rb
index 9c8e4dccb4..01fa0992ba 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_mc_global_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_mc_global_spec.rb
@@ -2,19 +2,19 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_mc_global?' do
   it 'returns true for a multi-cast address in the global scope' do
-    Addrinfo.ip('ff1e::').ipv6_mc_global?.should == true
-    Addrinfo.ip('fffe::').ipv6_mc_global?.should == true
-    Addrinfo.ip('ff0e::').ipv6_mc_global?.should == true
-    Addrinfo.ip('ff1e::1').ipv6_mc_global?.should == true
+    Addrinfo.ip('ff1e::').should.ipv6_mc_global?
+    Addrinfo.ip('fffe::').should.ipv6_mc_global?
+    Addrinfo.ip('ff0e::').should.ipv6_mc_global?
+    Addrinfo.ip('ff1e::1').should.ipv6_mc_global?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_mc_global?.should == false
-    Addrinfo.ip('ff1a::').ipv6_mc_global?.should == false
-    Addrinfo.ip('ff1f::1').ipv6_mc_global?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_mc_global?
+    Addrinfo.ip('ff1a::').should_not.ipv6_mc_global?
+    Addrinfo.ip('ff1f::1').should_not.ipv6_mc_global?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_mc_global?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_mc_global?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_mc_linklocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_mc_linklocal_spec.rb
index dd52a9ad8b..a1298919eb 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_mc_linklocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_mc_linklocal_spec.rb
@@ -2,18 +2,18 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_mc_linklocal?' do
   it 'returns true for a multi-cast link-local address' do
-    Addrinfo.ip('ff12::').ipv6_mc_linklocal?.should == true
-    Addrinfo.ip('ff02::').ipv6_mc_linklocal?.should == true
-    Addrinfo.ip('fff2::').ipv6_mc_linklocal?.should == true
-    Addrinfo.ip('ff12::1').ipv6_mc_linklocal?.should == true
+    Addrinfo.ip('ff12::').should.ipv6_mc_linklocal?
+    Addrinfo.ip('ff02::').should.ipv6_mc_linklocal?
+    Addrinfo.ip('fff2::').should.ipv6_mc_linklocal?
+    Addrinfo.ip('ff12::1').should.ipv6_mc_linklocal?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_mc_linklocal?.should == false
-    Addrinfo.ip('fff1::').ipv6_mc_linklocal?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_mc_linklocal?
+    Addrinfo.ip('fff1::').should_not.ipv6_mc_linklocal?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_mc_linklocal?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_mc_linklocal?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_mc_nodelocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_mc_nodelocal_spec.rb
index b3cf5ffbab..0aee952d88 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_mc_nodelocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_mc_nodelocal_spec.rb
@@ -2,17 +2,17 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_mc_nodelocal?' do
   it 'returns true for a multi-cast node-local address' do
-    Addrinfo.ip('ff11::').ipv6_mc_nodelocal?.should == true
-    Addrinfo.ip('ff01::').ipv6_mc_nodelocal?.should == true
-    Addrinfo.ip('fff1::').ipv6_mc_nodelocal?.should == true
-    Addrinfo.ip('ff11::1').ipv6_mc_nodelocal?.should == true
+    Addrinfo.ip('ff11::').should.ipv6_mc_nodelocal?
+    Addrinfo.ip('ff01::').should.ipv6_mc_nodelocal?
+    Addrinfo.ip('fff1::').should.ipv6_mc_nodelocal?
+    Addrinfo.ip('ff11::1').should.ipv6_mc_nodelocal?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_mc_nodelocal?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_mc_nodelocal?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_mc_nodelocal?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_mc_nodelocal?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_mc_orglocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_mc_orglocal_spec.rb
index 90653dd49c..2977a98d30 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_mc_orglocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_mc_orglocal_spec.rb
@@ -2,17 +2,17 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_mc_orglocal?' do
   it 'returns true for a multi-cast org-local address' do
-    Addrinfo.ip('ff18::').ipv6_mc_orglocal?.should == true
-    Addrinfo.ip('ff08::').ipv6_mc_orglocal?.should == true
-    Addrinfo.ip('fff8::').ipv6_mc_orglocal?.should == true
-    Addrinfo.ip('ff18::1').ipv6_mc_orglocal?.should == true
+    Addrinfo.ip('ff18::').should.ipv6_mc_orglocal?
+    Addrinfo.ip('ff08::').should.ipv6_mc_orglocal?
+    Addrinfo.ip('fff8::').should.ipv6_mc_orglocal?
+    Addrinfo.ip('ff18::1').should.ipv6_mc_orglocal?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_mc_orglocal?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_mc_orglocal?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_mc_orglocal?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_mc_orglocal?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_mc_sitelocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_mc_sitelocal_spec.rb
index 686b625e0d..58e5976a40 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_mc_sitelocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_mc_sitelocal_spec.rb
@@ -2,17 +2,17 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_mc_sitelocal?' do
   it 'returns true for a multi-cast site-local address' do
-    Addrinfo.ip('ff15::').ipv6_mc_sitelocal?.should == true
-    Addrinfo.ip('ff05::').ipv6_mc_sitelocal?.should == true
-    Addrinfo.ip('fff5::').ipv6_mc_sitelocal?.should == true
-    Addrinfo.ip('ff15::1').ipv6_mc_sitelocal?.should == true
+    Addrinfo.ip('ff15::').should.ipv6_mc_sitelocal?
+    Addrinfo.ip('ff05::').should.ipv6_mc_sitelocal?
+    Addrinfo.ip('fff5::').should.ipv6_mc_sitelocal?
+    Addrinfo.ip('ff15::1').should.ipv6_mc_sitelocal?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_mc_sitelocal?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_mc_sitelocal?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_mc_sitelocal?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_mc_sitelocal?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_multicast_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_multicast_spec.rb
index c25322869c..52787e5e53 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_multicast_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_multicast_spec.rb
@@ -8,41 +8,39 @@ describe "Addrinfo#ipv6_multicast?" do
     end
 
     it "returns true for a multicast address" do
-      @multicast.ipv6_multicast?.should be_false
+      @multicast.ipv6_multicast?.should == false
     end
 
     it "returns false for another address" do
-      @other.ipv6_multicast?.should be_false
+      @other.ipv6_multicast?.should == false
     end
   end
 
   describe "for an ipv6 socket" do
     it "returns true for a multicast address" do
-      Addrinfo.ip('ff00::').ipv6_multicast?.should == true
-      Addrinfo.ip('ff00::1').ipv6_multicast?.should == true
-      Addrinfo.ip('ff08::1').ipv6_multicast?.should == true
-      Addrinfo.ip('fff8::1').ipv6_multicast?.should == true
-
-      Addrinfo.ip('ff02::').ipv6_multicast?.should == true
-      Addrinfo.ip('ff02::1').ipv6_multicast?.should == true
-      Addrinfo.ip('ff0f::').ipv6_multicast?.should == true
+      Addrinfo.ip('ff00::').should.ipv6_multicast?
+      Addrinfo.ip('ff00::1').should.ipv6_multicast?
+      Addrinfo.ip('ff08::1').should.ipv6_multicast?
+      Addrinfo.ip('fff8::1').should.ipv6_multicast?
+
+      Addrinfo.ip('ff02::').should.ipv6_multicast?
+      Addrinfo.ip('ff02::1').should.ipv6_multicast?
+      Addrinfo.ip('ff0f::').should.ipv6_multicast?
     end
 
     it "returns false for another address" do
-      Addrinfo.ip('::1').ipv6_multicast?.should == false
-      Addrinfo.ip('fe80::').ipv6_multicast?.should == false
+      Addrinfo.ip('::1').should_not.ipv6_multicast?
+      Addrinfo.ip('fe80::').should_not.ipv6_multicast?
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv6_multicast?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv6_multicast?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_sitelocal_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_sitelocal_spec.rb
index dd202a1749..9158eb5809 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_sitelocal_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_sitelocal_spec.rb
@@ -5,19 +5,19 @@ guard -> { SocketSpecs.ipv6_available? } do
   describe 'Addrinfo#ipv6_sitelocal?' do
     platform_is_not :aix do
       it 'returns true for a site-local address' do
-        Addrinfo.ip('feef::').ipv6_sitelocal?.should == true
-        Addrinfo.ip('fee0::').ipv6_sitelocal?.should == true
-        Addrinfo.ip('fee2::').ipv6_sitelocal?.should == true
-        Addrinfo.ip('feef::1').ipv6_sitelocal?.should == true
+        Addrinfo.ip('feef::').should.ipv6_sitelocal?
+        Addrinfo.ip('fee0::').should.ipv6_sitelocal?
+        Addrinfo.ip('fee2::').should.ipv6_sitelocal?
+        Addrinfo.ip('feef::1').should.ipv6_sitelocal?
       end
     end
 
     it 'returns false for a regular IPv6 address' do
-      Addrinfo.ip('::1').ipv6_sitelocal?.should == false
+      Addrinfo.ip('::1').should_not.ipv6_sitelocal?
     end
 
     it 'returns false for an IPv4 address' do
-      Addrinfo.ip('127.0.0.1').ipv6_sitelocal?.should == false
+      Addrinfo.ip('127.0.0.1').should_not.ipv6_sitelocal?
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_spec.rb
index 131e38849c..9fa8e9bd0c 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_spec.rb
@@ -7,7 +7,7 @@ describe "Addrinfo#ipv6?" do
     end
 
     it "returns true" do
-      @addrinfo.ipv6?.should be_false
+      @addrinfo.ipv6?.should == false
     end
   end
 
@@ -17,19 +17,17 @@ describe "Addrinfo#ipv6?" do
     end
 
     it "returns false" do
-      @addrinfo.ipv6?.should be_true
+      @addrinfo.ipv6?.should == true
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns false" do
-        @addrinfo.ipv6?.should be_false
-      end
+    it "returns false" do
+      @addrinfo.ipv6?.should == false
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_to_ipv4_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_to_ipv4_spec.rb
index 6dfaf531ae..d1436d4527 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_to_ipv4_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_to_ipv4_spec.rb
@@ -6,7 +6,7 @@ guard -> { SocketSpecs.ipv6_available? } do
     it 'returns an Addrinfo for ::192.168.1.1' do
       addr = Addrinfo.ip('::192.168.1.1').ipv6_to_ipv4
 
-      addr.should be_an_instance_of(Addrinfo)
+      addr.should.instance_of?(Addrinfo)
 
       addr.afamily.should    == Socket::AF_INET
       addr.ip_address.should == '192.168.1.1'
@@ -16,7 +16,7 @@ guard -> { SocketSpecs.ipv6_available? } do
       it 'returns an Addrinfo for ::0.0.1.1' do
         addr = Addrinfo.ip('::0.0.1.1').ipv6_to_ipv4
 
-        addr.should be_an_instance_of(Addrinfo)
+        addr.should.instance_of?(Addrinfo)
 
         addr.afamily.should    == Socket::AF_INET
         addr.ip_address.should == '0.0.1.1'
@@ -25,7 +25,7 @@ guard -> { SocketSpecs.ipv6_available? } do
       it 'returns an Addrinfo for ::0.0.1.0' do
         addr = Addrinfo.ip('::0.0.1.0').ipv6_to_ipv4
 
-        addr.should be_an_instance_of(Addrinfo)
+        addr.should.instance_of?(Addrinfo)
 
         addr.afamily.should    == Socket::AF_INET
         addr.ip_address.should == '0.0.1.0'
@@ -34,7 +34,7 @@ guard -> { SocketSpecs.ipv6_available? } do
       it 'returns an Addrinfo for ::0.1.0.0' do
         addr = Addrinfo.ip('::0.1.0.0').ipv6_to_ipv4
 
-        addr.should be_an_instance_of(Addrinfo)
+        addr.should.instance_of?(Addrinfo)
 
         addr.afamily.should    == Socket::AF_INET
         addr.ip_address.should == '0.1.0.0'
@@ -44,27 +44,27 @@ guard -> { SocketSpecs.ipv6_available? } do
     it 'returns an Addrinfo for ::ffff:192.168.1.1' do
       addr = Addrinfo.ip('::ffff:192.168.1.1').ipv6_to_ipv4
 
-      addr.should be_an_instance_of(Addrinfo)
+      addr.should.instance_of?(Addrinfo)
 
       addr.afamily.should    == Socket::AF_INET
       addr.ip_address.should == '192.168.1.1'
     end
 
     it 'returns nil for ::0.0.0.1' do
-      Addrinfo.ip('::0.0.0.1').ipv6_to_ipv4.should be_nil
+      Addrinfo.ip('::0.0.0.1').ipv6_to_ipv4.should == nil
     end
 
     it 'returns nil for a pure IPv6 Addrinfo' do
-      Addrinfo.ip('::1').ipv6_to_ipv4.should be_nil
+      Addrinfo.ip('::1').ipv6_to_ipv4.should == nil
     end
 
     it 'returns nil for an IPv4 Addrinfo' do
-      Addrinfo.ip('192.168.1.1').ipv6_to_ipv4.should be_nil
+      Addrinfo.ip('192.168.1.1').ipv6_to_ipv4.should == nil
     end
 
-    with_feature :unix_socket do
+    describe 'for a unix socket' do
       it 'returns nil for a UNIX Addrinfo' do
-        Addrinfo.unix('foo').ipv6_to_ipv4.should be_nil
+        Addrinfo.unix('foo').ipv6_to_ipv4.should == nil
       end
     end
   end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_unique_local_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_unique_local_spec.rb
index b80a15fcb0..22f0fa3b75 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_unique_local_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_unique_local_spec.rb
@@ -2,17 +2,17 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_unique_local?' do
   it 'returns true for an unique local IPv6 address' do
-    Addrinfo.ip('fc00::').ipv6_unique_local?.should == true
-    Addrinfo.ip('fd00::').ipv6_unique_local?.should == true
-    Addrinfo.ip('fcff::').ipv6_unique_local?.should == true
+    Addrinfo.ip('fc00::').should.ipv6_unique_local?
+    Addrinfo.ip('fd00::').should.ipv6_unique_local?
+    Addrinfo.ip('fcff::').should.ipv6_unique_local?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_unique_local?.should == false
-    Addrinfo.ip('fe00::').ipv6_unique_local?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_unique_local?
+    Addrinfo.ip('fe00::').should_not.ipv6_unique_local?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_unique_local?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_unique_local?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_unspecified_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_unspecified_spec.rb
index dd79d57503..d63979ceda 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_unspecified_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_unspecified_spec.rb
@@ -2,14 +2,14 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_unspecified?' do
   it 'returns true for an unspecified IPv6 address' do
-    Addrinfo.ip('::').ipv6_unspecified?.should == true
+    Addrinfo.ip('::').should.ipv6_unspecified?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_unspecified?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_unspecified?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_unspecified?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_unspecified?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_v4compat_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_v4compat_spec.rb
index ab8388a21b..21ca85af99 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_v4compat_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_v4compat_spec.rb
@@ -2,19 +2,19 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_v4compat?' do
   it 'returns true for an IPv4 compatible address' do
-    Addrinfo.ip('::127.0.0.1').ipv6_v4compat?.should == true
-    Addrinfo.ip('::192.168.1.1').ipv6_v4compat?.should == true
+    Addrinfo.ip('::127.0.0.1').should.ipv6_v4compat?
+    Addrinfo.ip('::192.168.1.1').should.ipv6_v4compat?
   end
 
   it 'returns false for an IPv4 mapped address' do
-    Addrinfo.ip('::ffff:192.168.1.1').ipv6_v4compat?.should == false
+    Addrinfo.ip('::ffff:192.168.1.1').should_not.ipv6_v4compat?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_v4compat?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_v4compat?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_v4compat?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_v4compat?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/ipv6_v4mapped_spec.rb b/spec/ruby/library/socket/addrinfo/ipv6_v4mapped_spec.rb
index 82b272c165..7dac0e75db 100644
--- a/spec/ruby/library/socket/addrinfo/ipv6_v4mapped_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/ipv6_v4mapped_spec.rb
@@ -2,19 +2,19 @@ require_relative '../spec_helper'
 
 describe 'Addrinfo#ipv6_v4mapped?' do
   it 'returns true for an IPv4 compatible address' do
-    Addrinfo.ip('::ffff:192.168.1.1').ipv6_v4mapped?.should == true
+    Addrinfo.ip('::ffff:192.168.1.1').should.ipv6_v4mapped?
   end
 
   it 'returns false for an IPv4 compatible address' do
-    Addrinfo.ip('::192.168.1.1').ipv6_v4mapped?.should == false
-    Addrinfo.ip('::127.0.0.1').ipv6_v4mapped?.should == false
+    Addrinfo.ip('::192.168.1.1').should_not.ipv6_v4mapped?
+    Addrinfo.ip('::127.0.0.1').should_not.ipv6_v4mapped?
   end
 
   it 'returns false for a regular IPv6 address' do
-    Addrinfo.ip('::1').ipv6_v4mapped?.should == false
+    Addrinfo.ip('::1').should_not.ipv6_v4mapped?
   end
 
   it 'returns false for an IPv4 address' do
-    Addrinfo.ip('127.0.0.1').ipv6_v4mapped?.should == false
+    Addrinfo.ip('127.0.0.1').should_not.ipv6_v4mapped?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/listen_spec.rb b/spec/ruby/library/socket/addrinfo/listen_spec.rb
index 714a96ed6c..80bcdc7f83 100644
--- a/spec/ruby/library/socket/addrinfo/listen_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/listen_spec.rb
@@ -13,12 +13,12 @@ describe 'Addrinfo#listen' do
   it 'returns a Socket when no block is given' do
     @socket = @addr.listen
 
-    @socket.should be_an_instance_of(Socket)
+    @socket.should.instance_of?(Socket)
   end
 
   it 'yields the Socket if a block is given' do
     @addr.listen do |socket|
-      socket.should be_an_instance_of(Socket)
+      socket.should.instance_of?(Socket)
     end
   end
 
@@ -29,6 +29,6 @@ describe 'Addrinfo#listen' do
       socket = sock
     end
 
-    socket.closed?.should == true
+    socket.should.closed?
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/marshal_dump_spec.rb b/spec/ruby/library/socket/addrinfo/marshal_dump_spec.rb
index c4220a6f3e..438b04a99c 100644
--- a/spec/ruby/library/socket/addrinfo/marshal_dump_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/marshal_dump_spec.rb
@@ -8,7 +8,7 @@ describe 'Addrinfo#marshal_dump' do
     end
 
     it 'returns an Array' do
-      @addr.marshal_dump.should be_an_instance_of(Array)
+      @addr.marshal_dump.should.instance_of?(Array)
     end
 
     describe 'the returned Array' do
@@ -32,10 +32,8 @@ describe 'Addrinfo#marshal_dump' do
         @array[3].should == 'SOCK_STREAM'
       end
 
-      platform_is_not :'solaris2.10' do # i386-solaris
-        it 'includes the protocol as the 5th value' do
-          @array[4].should == 'IPPROTO_TCP'
-        end
+      it 'includes the protocol as the 5th value' do
+        @array[4].should == 'IPPROTO_TCP'
       end
 
       it 'includes the canonical name as the 6th value' do
@@ -44,40 +42,38 @@ describe 'Addrinfo#marshal_dump' do
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using a UNIX Addrinfo' do
+  describe 'using a UNIX Addrinfo' do
+    before do
+      @addr = Addrinfo.unix('foo')
+    end
+
+    it 'returns an Array' do
+      @addr.marshal_dump.should.instance_of?(Array)
+    end
+
+    describe 'the returned Array' do
       before do
-        @addr = Addrinfo.unix('foo')
+        @array = @addr.marshal_dump
       end
 
-      it 'returns an Array' do
-        @addr.marshal_dump.should be_an_instance_of(Array)
+      it 'includes the address family as the 1st value' do
+        @array[0].should == 'AF_UNIX'
       end
 
-      describe 'the returned Array' do
-        before do
-          @array = @addr.marshal_dump
-        end
-
-        it 'includes the address family as the 1st value' do
-          @array[0].should == 'AF_UNIX'
-        end
-
-        it 'includes the UNIX path as the 2nd value' do
-          @array[1].should == @addr.unix_path
-        end
+      it 'includes the UNIX path as the 2nd value' do
+        @array[1].should == @addr.unix_path
+      end
 
-        it 'includes the protocol family as the 3rd value' do
-          @array[2].should == 'PF_UNIX'
-        end
+      it 'includes the protocol family as the 3rd value' do
+        @array[2].should == 'PF_UNIX'
+      end
 
-        it 'includes the socket type as the 4th value' do
-          @array[3].should == 'SOCK_STREAM'
-        end
+      it 'includes the socket type as the 4th value' do
+        @array[3].should == 'SOCK_STREAM'
+      end
 
-        it 'includes the protocol as the 5th value' do
-          @array[4].should == 0
-        end
+      it 'includes the protocol as the 5th value' do
+        @array[4].should == 0
       end
     end
   end
diff --git a/spec/ruby/library/socket/addrinfo/marshal_load_spec.rb b/spec/ruby/library/socket/addrinfo/marshal_load_spec.rb
index aa20865224..02cef90115 100644
--- a/spec/ruby/library/socket/addrinfo/marshal_load_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/marshal_load_spec.rb
@@ -18,18 +18,16 @@ describe 'Addrinfo#marshal_load' do
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using a UNIX socket' do
-      it 'returns a new Addrinfo' do
-        source = Addrinfo.unix('foo')
-        addr   = Marshal.load(Marshal.dump(source))
+  describe 'using a UNIX socket' do
+    it 'returns a new Addrinfo' do
+      source = Addrinfo.unix('foo')
+      addr   = Marshal.load(Marshal.dump(source))
 
-        addr.afamily.should   == source.afamily
-        addr.pfamily.should   == source.pfamily
-        addr.socktype.should  == source.socktype
-        addr.protocol.should  == source.protocol
-        addr.unix_path.should == source.unix_path
-      end
+      addr.afamily.should   == source.afamily
+      addr.pfamily.should   == source.pfamily
+      addr.socktype.should  == source.socktype
+      addr.protocol.should  == source.protocol
+      addr.unix_path.should == source.unix_path
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/pfamily_spec.rb b/spec/ruby/library/socket/addrinfo/pfamily_spec.rb
index 984744a964..da530b7fdc 100644
--- a/spec/ruby/library/socket/addrinfo/pfamily_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/pfamily_spec.rb
@@ -29,15 +29,13 @@ describe "Addrinfo#pfamily" do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
-
-      it "returns Socket::PF_UNIX" do
-        @addrinfo.pfamily.should == Socket::PF_UNIX
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
+
+    it "returns Socket::PF_UNIX" do
+      @addrinfo.pfamily.should == Socket::PF_UNIX
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/protocol_spec.rb b/spec/ruby/library/socket/addrinfo/protocol_spec.rb
index ea143fc4a8..f6ffc9acf9 100644
--- a/spec/ruby/library/socket/addrinfo/protocol_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/protocol_spec.rb
@@ -10,15 +10,13 @@ describe "Addrinfo#protocol" do
     Addrinfo.tcp('::1', 80).protocol.should == Socket::IPPROTO_TCP
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns 0" do
-        @addrinfo.protocol.should == 0
-      end
+    it "returns 0" do
+      @addrinfo.protocol.should == 0
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/shared/to_sockaddr.rb b/spec/ruby/library/socket/addrinfo/shared/to_sockaddr.rb
index c32da5986d..70d6bfbbfe 100644
--- a/spec/ruby/library/socket/addrinfo/shared/to_sockaddr.rb
+++ b/spec/ruby/library/socket/addrinfo/shared/to_sockaddr.rb
@@ -1,5 +1,4 @@
-describe :socket_addrinfo_to_sockaddr, :shared => true do
-
+describe :socket_addrinfo_to_sockaddr, shared: true do
   describe "for an ipv4 socket" do
     before :each do
       @addrinfo = Addrinfo.tcp("127.0.0.1", 80)
@@ -20,15 +19,13 @@ describe :socket_addrinfo_to_sockaddr, :shared => true do
     end
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns a sockaddr packed structure" do
-        @addrinfo.send(@method).should == Socket.sockaddr_un('/tmp/sock')
-      end
+    it "returns a sockaddr packed structure" do
+      @addrinfo.send(@method).should == Socket.sockaddr_un('/tmp/sock')
     end
   end
 
@@ -47,5 +44,4 @@ describe :socket_addrinfo_to_sockaddr, :shared => true do
       addr.send(@method).should == Socket.sockaddr_in(0, '')
     end
   end
-
 end
diff --git a/spec/ruby/library/socket/addrinfo/socktype_spec.rb b/spec/ruby/library/socket/addrinfo/socktype_spec.rb
index b994bea140..e5f02cd759 100644
--- a/spec/ruby/library/socket/addrinfo/socktype_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/socktype_spec.rb
@@ -9,15 +9,13 @@ describe "Addrinfo#socktype" do
     Addrinfo.tcp('127.0.0.1', 80).socktype.should == Socket::SOCK_STREAM
   end
 
-  with_feature :unix_socket do
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns Socket::SOCK_STREAM" do
-        @addrinfo.socktype.should == Socket::SOCK_STREAM
-      end
+    it "returns Socket::SOCK_STREAM" do
+      @addrinfo.socktype.should == Socket::SOCK_STREAM
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/tcp_spec.rb b/spec/ruby/library/socket/addrinfo/tcp_spec.rb
index c74c9c21c2..0669de16a6 100644
--- a/spec/ruby/library/socket/addrinfo/tcp_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/tcp_spec.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe 'Addrinfo.tcp' do
   SocketSpecs.each_ip_protocol do |family, ip_address|
     it 'returns an Addrinfo instance' do
-      Addrinfo.tcp(ip_address, 80).should be_an_instance_of(Addrinfo)
+      Addrinfo.tcp(ip_address, 80).should.instance_of?(Addrinfo)
     end
 
     it 'sets the IP address' do
diff --git a/spec/ruby/library/socket/addrinfo/udp_spec.rb b/spec/ruby/library/socket/addrinfo/udp_spec.rb
index b05cbf9b0b..51d7f5588e 100644
--- a/spec/ruby/library/socket/addrinfo/udp_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/udp_spec.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe 'Addrinfo.udp' do
   SocketSpecs.each_ip_protocol do |family, ip_address|
     it 'returns an Addrinfo instance' do
-      Addrinfo.udp(ip_address, 80).should be_an_instance_of(Addrinfo)
+      Addrinfo.udp(ip_address, 80).should.instance_of?(Addrinfo)
     end
 
     it 'sets the IP address' do
@@ -27,10 +27,8 @@ describe 'Addrinfo.udp' do
       Addrinfo.udp(ip_address, 80).socktype.should == Socket::SOCK_DGRAM
     end
 
-    platform_is_not :solaris do
-      it 'sets the socket protocol' do
-        Addrinfo.udp(ip_address, 80).protocol.should == Socket::IPPROTO_UDP
-      end
+    it 'sets the socket protocol' do
+      Addrinfo.udp(ip_address, 80).protocol.should == Socket::IPPROTO_UDP
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/unix_path_spec.rb b/spec/ruby/library/socket/addrinfo/unix_path_spec.rb
index 6bfb56a4ac..c15075bce3 100644
--- a/spec/ruby/library/socket/addrinfo/unix_path_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/unix_path_spec.rb
@@ -1,37 +1,35 @@
 require_relative '../spec_helper'
 
-with_feature :unix_socket do
-  describe "Addrinfo#unix_path" do
-    describe "for an ipv4 socket" do
+describe "Addrinfo#unix_path" do
+  describe "for an ipv4 socket" do
 
-      before :each do
-        @addrinfo = Addrinfo.tcp("127.0.0.1", 80)
-      end
-
-      it "raises an exception" do
-        -> { @addrinfo.unix_path }.should raise_error(SocketError)
-      end
+    before :each do
+      @addrinfo = Addrinfo.tcp("127.0.0.1", 80)
+    end
 
+    it "raises an exception" do
+      -> { @addrinfo.unix_path }.should.raise(SocketError)
     end
 
-    describe "for an ipv6 socket" do
-      before :each do
-        @addrinfo = Addrinfo.tcp("::1", 80)
-      end
+  end
 
-      it "raises an exception" do
-        -> { @addrinfo.unix_path }.should raise_error(SocketError)
-      end
+  describe "for an ipv6 socket" do
+    before :each do
+      @addrinfo = Addrinfo.tcp("::1", 80)
     end
 
-    describe "for a unix socket" do
-      before :each do
-        @addrinfo = Addrinfo.unix("/tmp/sock")
-      end
+    it "raises an exception" do
+      -> { @addrinfo.unix_path }.should.raise(SocketError)
+    end
+  end
+
+  describe "for a unix socket" do
+    before :each do
+      @addrinfo = Addrinfo.unix("/tmp/sock")
+    end
 
-      it "returns the socket path" do
-        @addrinfo.unix_path.should == "/tmp/sock"
-      end
+    it "returns the socket path" do
+      @addrinfo.unix_path.should == "/tmp/sock"
     end
   end
 end
diff --git a/spec/ruby/library/socket/addrinfo/unix_spec.rb b/spec/ruby/library/socket/addrinfo/unix_spec.rb
index 4596ece17e..da65e13efb 100644
--- a/spec/ruby/library/socket/addrinfo/unix_spec.rb
+++ b/spec/ruby/library/socket/addrinfo/unix_spec.rb
@@ -1,36 +1,34 @@
 require_relative '../spec_helper'
 
-with_feature :unix_socket do
-  describe 'Addrinfo.unix' do
-    it 'returns an Addrinfo instance' do
-      Addrinfo.unix('socket').should be_an_instance_of(Addrinfo)
-    end
+describe 'Addrinfo.unix' do
+  it 'returns an Addrinfo instance' do
+    Addrinfo.unix('socket').should.instance_of?(Addrinfo)
+  end
 
-    it 'sets the IP address' do
-      Addrinfo.unix('socket').unix_path.should == 'socket'
-    end
+  it 'sets the IP address' do
+    Addrinfo.unix('socket').unix_path.should == 'socket'
+  end
 
-    it 'sets the address family' do
-      Addrinfo.unix('socket').afamily.should == Socket::AF_UNIX
-    end
+  it 'sets the address family' do
+    Addrinfo.unix('socket').afamily.should == Socket::AF_UNIX
+  end
 
-    it 'sets the protocol family' do
-      Addrinfo.unix('socket').pfamily.should == Socket::PF_UNIX
-    end
+  it 'sets the protocol family' do
+    Addrinfo.unix('socket').pfamily.should == Socket::PF_UNIX
+  end
 
-    it 'sets the socket type' do
-      Addrinfo.unix('socket').socktype.should == Socket::SOCK_STREAM
-    end
+  it 'sets the socket type' do
+    Addrinfo.unix('socket').socktype.should == Socket::SOCK_STREAM
+  end
 
-    it 'sets a custom socket type' do
-      addr = Addrinfo.unix('socket', Socket::SOCK_DGRAM)
+  it 'sets a custom socket type' do
+    addr = Addrinfo.unix('socket', Socket::SOCK_DGRAM)
 
-      addr.socktype.should == Socket::SOCK_DGRAM
-    end
+    addr.socktype.should == Socket::SOCK_DGRAM
+  end
 
-    it 'sets the socket protocol to 0' do
-      Addrinfo.unix('socket').protocol.should == 0
-    end
+  it 'sets the socket protocol to 0' do
+    Addrinfo.unix('socket').protocol.should == 0
   end
 end
 
@@ -42,7 +40,7 @@ describe "Addrinfo#unix?" do
     end
 
     it "returns false" do
-      @addrinfo.unix?.should be_false
+      @addrinfo.unix?.should == false
     end
 
   end
@@ -53,7 +51,7 @@ describe "Addrinfo#unix?" do
     end
 
     it "returns false" do
-      @addrinfo.unix?.should be_false
+      @addrinfo.unix?.should == false
     end
   end
 
@@ -64,7 +62,7 @@ describe "Addrinfo#unix?" do
       end
 
       it "returns true" do
-        @addrinfo.unix?.should be_true
+        @addrinfo.unix?.should == true
       end
     end
   end
diff --git a/spec/ruby/library/socket/ancillarydata/cmsg_is_spec.rb b/spec/ruby/library/socket/ancillarydata/cmsg_is_spec.rb
index c54ee29825..c77f3bdbae 100644
--- a/spec/ruby/library/socket/ancillarydata/cmsg_is_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/cmsg_is_spec.rb
@@ -26,7 +26,7 @@ with_feature :ancillary_data do
       end
 
       it 'raises SocketError when comparing with :IPV6 and :RIGHTS' do
-        -> { @data.cmsg_is?(:IPV6, :RIGHTS) }.should raise_error(SocketError)
+        -> { @data.cmsg_is?(:IPV6, :RIGHTS) }.should.raise(SocketError)
       end
     end
   end
diff --git a/spec/ruby/library/socket/ancillarydata/initialize_spec.rb b/spec/ruby/library/socket/ancillarydata/initialize_spec.rb
index 344d1485c5..60f5ac7a90 100644
--- a/spec/ruby/library/socket/ancillarydata/initialize_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/initialize_spec.rb
@@ -106,7 +106,7 @@ with_feature :ancillary_data do
         Socket::AncillaryData.new(:INET, :SOCKET, :RIGHTS, '').type.should == Socket::SCM_RIGHTS
       end
 
-      platform_is_not :"solaris2.10", :aix do
+      platform_is_not :aix do
         it 'sets the type to SCM_TIMESTAMP when using :TIMESTAMP as the type argument' do
           Socket::AncillaryData.new(:INET, :SOCKET, :TIMESTAMP, '').type.should == Socket::SCM_TIMESTAMP
         end
@@ -115,25 +115,25 @@ with_feature :ancillary_data do
       it 'raises TypeError when using a numeric string as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :IGMP, Socket::SCM_RIGHTS.to_s, '')
-        }.should raise_error(TypeError)
+        }.should.raise(TypeError)
       end
 
       it 'raises SocketError when using :RECVTTL as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :SOCKET, :RECVTTL, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :MOO as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :SOCKET, :MOO, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :IP_RECVTTL as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :SOCKET, :IP_RECVTTL, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -157,13 +157,13 @@ with_feature :ancillary_data do
       it 'raises SocketError when using :RIGHTS as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :IP, :RIGHTS, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :MOO as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :IP, :MOO, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -181,13 +181,13 @@ with_feature :ancillary_data do
       it 'raises SocketError when using :RIGHTS as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :IPV6, :RIGHTS, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :MOO as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :IPV6, :MOO, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -207,13 +207,13 @@ with_feature :ancillary_data do
       it 'raises SocketError when using :RIGHTS as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :TCP, :RIGHTS, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :MOO as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :TCP, :MOO, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -227,13 +227,13 @@ with_feature :ancillary_data do
       it 'raises SocketError when using :RIGHTS as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :UDP, :RIGHTS, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
 
       it 'raises SocketError when using :MOO as the type argument' do
         -> {
           Socket::AncillaryData.new(:INET, :UDP, :MOO, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -245,7 +245,7 @@ with_feature :ancillary_data do
       it 'raises SocketError when using :CORK sa the type argument' do
         -> {
           Socket::AncillaryData.new(:UNIX, :SOCKET, :CORK, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -253,7 +253,7 @@ with_feature :ancillary_data do
       it 'raises SocketError' do
         -> {
           Socket::AncillaryData.new(:UNIX, :IP, :RECVTTL, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -261,7 +261,7 @@ with_feature :ancillary_data do
       it 'raises SocketError' do
         -> {
           Socket::AncillaryData.new(:UNIX, :IPV6, :NEXTHOP, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -269,7 +269,7 @@ with_feature :ancillary_data do
       it 'raises SocketError' do
         -> {
           Socket::AncillaryData.new(:UNIX, :TCP, :CORK, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
 
@@ -277,7 +277,7 @@ with_feature :ancillary_data do
       it 'raises SocketError' do
         -> {
           Socket::AncillaryData.new(:UNIX, :UDP, :CORK, '')
-        }.should raise_error(SocketError)
+        }.should.raise(SocketError)
       end
     end
   end
diff --git a/spec/ruby/library/socket/ancillarydata/int_spec.rb b/spec/ruby/library/socket/ancillarydata/int_spec.rb
index fe41a30a1a..10c5dea436 100644
--- a/spec/ruby/library/socket/ancillarydata/int_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/int_spec.rb
@@ -7,7 +7,7 @@ with_feature :ancillary_data do
     end
 
     it 'returns a Socket::AncillaryData' do
-      @data.should be_an_instance_of(Socket::AncillaryData)
+      @data.should.instance_of?(Socket::AncillaryData)
     end
 
     it 'sets the family to AF_INET' do
@@ -37,7 +37,7 @@ with_feature :ancillary_data do
     it 'raises when the data is not an Integer' do
       data = Socket::AncillaryData.new(:UNIX, :SOCKET, :RIGHTS, 'ugh')
 
-      -> { data.int }.should raise_error(TypeError)
+      -> { data.int }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/ancillarydata/ip_pktinfo_spec.rb b/spec/ruby/library/socket/ancillarydata/ip_pktinfo_spec.rb
index 84910a038a..065bcf1f39 100644
--- a/spec/ruby/library/socket/ancillarydata/ip_pktinfo_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/ip_pktinfo_spec.rb
@@ -8,7 +8,7 @@ with_feature :ancillary_data, :pktinfo do
       end
 
       it 'returns a Socket::AncillaryData' do
-        @data.should be_an_instance_of(Socket::AncillaryData)
+        @data.should.instance_of?(Socket::AncillaryData)
       end
 
       it 'sets the family to AF_INET' do
@@ -32,7 +32,7 @@ with_feature :ancillary_data, :pktinfo do
       end
 
       it 'returns a Socket::AncillaryData' do
-        @data.should be_an_instance_of(Socket::AncillaryData)
+        @data.should.instance_of?(Socket::AncillaryData)
       end
 
       it 'sets the family to AF_INET' do
@@ -58,7 +58,7 @@ with_feature :ancillary_data, :pktinfo do
       end
 
       it 'returns an Array' do
-        @data.ip_pktinfo.should be_an_instance_of(Array)
+        @data.ip_pktinfo.should.instance_of?(Array)
       end
 
       describe 'the returned Array' do
@@ -67,15 +67,15 @@ with_feature :ancillary_data, :pktinfo do
         end
 
         it 'stores an Addrinfo at index 0' do
-          @info[0].should be_an_instance_of(Addrinfo)
+          @info[0].should.instance_of?(Addrinfo)
         end
 
         it 'stores the ifindex at index 1' do
-          @info[1].should be_kind_of(Integer)
+          @info[1].should.is_a?(Integer)
         end
 
         it 'stores an Addrinfo at index 2' do
-          @info[2].should be_an_instance_of(Addrinfo)
+          @info[2].should.instance_of?(Addrinfo)
         end
       end
 
@@ -89,7 +89,7 @@ with_feature :ancillary_data, :pktinfo do
         end
 
         it 'is not the same object as the input Addrinfo' do
-          @addr.should_not equal @source
+          @addr.should_not.equal? @source
         end
       end
 
@@ -109,7 +109,7 @@ with_feature :ancillary_data, :pktinfo do
         end
 
         it 'is not the same object as the input Addrinfo' do
-          @addr.should_not equal @dest
+          @addr.should_not.equal? @dest
         end
       end
     end
diff --git a/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_addr_spec.rb b/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_addr_spec.rb
index f70fe27d6a..7c630218d1 100644
--- a/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_addr_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_addr_spec.rb
@@ -5,7 +5,7 @@ with_feature :ancillary_data, :ipv6_pktinfo do
     it 'returns an Addrinfo' do
       data = Socket::AncillaryData.ipv6_pktinfo(Addrinfo.ip('::1'), 4)
 
-      data.ipv6_pktinfo_addr.should be_an_instance_of(Addrinfo)
+      data.ipv6_pktinfo_addr.should.instance_of?(Addrinfo)
     end
   end
 end
diff --git a/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_spec.rb b/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_spec.rb
index 0fffc720dc..b5b779c36e 100644
--- a/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/ipv6_pktinfo_spec.rb
@@ -7,7 +7,7 @@ with_feature :ancillary_data, :ipv6_pktinfo do
     end
 
     it 'returns a Socket::AncillaryData' do
-      @data.should be_an_instance_of(Socket::AncillaryData)
+      @data.should.instance_of?(Socket::AncillaryData)
     end
 
     it 'sets the family to AF_INET' do
@@ -31,7 +31,7 @@ with_feature :ancillary_data, :ipv6_pktinfo do
       end
 
       it 'returns an Array' do
-        @data.ipv6_pktinfo.should be_an_instance_of(Array)
+        @data.ipv6_pktinfo.should.instance_of?(Array)
       end
 
       describe 'the returned Array' do
@@ -40,11 +40,11 @@ with_feature :ancillary_data, :ipv6_pktinfo do
         end
 
         it 'stores an Addrinfo at index 0' do
-          @info[0].should be_an_instance_of(Addrinfo)
+          @info[0].should.instance_of?(Addrinfo)
         end
 
         it 'stores the ifindex at index 1' do
-          @info[1].should be_kind_of(Integer)
+          @info[1].should.is_a?(Integer)
         end
       end
 
@@ -58,7 +58,7 @@ with_feature :ancillary_data, :ipv6_pktinfo do
         end
 
         it 'is not the same object as the input Addrinfo' do
-          @addr.should_not equal @source
+          @addr.should_not.equal? @source
         end
       end
 
diff --git a/spec/ruby/library/socket/ancillarydata/unix_rights_spec.rb b/spec/ruby/library/socket/ancillarydata/unix_rights_spec.rb
index 65ffcb01af..6dd144ba5a 100644
--- a/spec/ruby/library/socket/ancillarydata/unix_rights_spec.rb
+++ b/spec/ruby/library/socket/ancillarydata/unix_rights_spec.rb
@@ -26,7 +26,7 @@ with_feature :ancillary_data do
 
     describe 'using non IO objects' do
       it 'raises TypeError' do
-        -> { Socket::AncillaryData.unix_rights(10) }.should raise_error(TypeError)
+        -> { Socket::AncillaryData.unix_rights(10) }.should.raise(TypeError)
       end
     end
   end
@@ -41,20 +41,20 @@ with_feature :ancillary_data do
     it 'returns nil when the data is not a list of file descriptors' do
       data = Socket::AncillaryData.new(:UNIX, :SOCKET, :RIGHTS, '')
 
-      data.unix_rights.should be_nil
+      data.unix_rights.should == nil
     end
 
     it 'raises TypeError when the level is not SOL_SOCKET' do
       data = Socket::AncillaryData.new(:INET, :IP, :RECVTTL, '')
 
-      -> { data.unix_rights }.should raise_error(TypeError)
+      -> { data.unix_rights }.should.raise(TypeError)
     end
 
-    platform_is_not :"solaris2.10", :aix do
+    platform_is_not :aix do
       it 'raises TypeError when the type is not SCM_RIGHTS' do
         data = Socket::AncillaryData.new(:INET, :SOCKET, :TIMESTAMP, '')
 
-        -> { data.unix_rights }.should raise_error(TypeError)
+        -> { data.unix_rights }.should.raise(TypeError)
       end
     end
   end
diff --git a/spec/ruby/library/socket/basicsocket/close_read_spec.rb b/spec/ruby/library/socket/basicsocket/close_read_spec.rb
index f317b34955..35bec203d7 100644
--- a/spec/ruby/library/socket/basicsocket/close_read_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/close_read_spec.rb
@@ -12,32 +12,32 @@ describe "Socket::BasicSocket#close_read" do
 
   it "closes the reading end of the socket" do
     @server.close_read
-    -> { @server.read }.should raise_error(IOError)
+    -> { @server.read }.should.raise(IOError)
   end
 
   it 'does not raise when called on a socket already closed for reading' do
     @server.close_read
     @server.close_read
-    -> { @server.read }.should raise_error(IOError)
+    -> { @server.read }.should.raise(IOError)
   end
 
   it 'does not fully close the socket' do
     @server.close_read
-    @server.closed?.should be_false
+    @server.closed?.should == false
   end
 
   it "fully closes the socket if it was already closed for writing" do
     @server.close_write
     @server.close_read
-    @server.closed?.should be_true
+    @server.closed?.should == true
   end
 
   it 'raises IOError when called on a fully closed socket' do
     @server.close
-    -> { @server.close_read }.should raise_error(IOError)
+    -> { @server.close_read }.should.raise(IOError)
   end
 
   it "returns nil" do
-    @server.close_read.should be_nil
+    @server.close_read.should == nil
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/close_write_spec.rb b/spec/ruby/library/socket/basicsocket/close_write_spec.rb
index 232cfbb7c6..c1b6d9e9ef 100644
--- a/spec/ruby/library/socket/basicsocket/close_write_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/close_write_spec.rb
@@ -12,18 +12,18 @@ describe "Socket::BasicSocket#close_write" do
 
   it "closes the writing end of the socket" do
     @server.close_write
-    -> { @server.write("foo") }.should raise_error(IOError)
+    -> { @server.write("foo") }.should.raise(IOError)
   end
 
   it 'does not raise when called on a socket already closed for writing' do
     @server.close_write
     @server.close_write
-    -> { @server.write("foo") }.should raise_error(IOError)
+    -> { @server.write("foo") }.should.raise(IOError)
   end
 
   it 'does not fully close the socket' do
     @server.close_write
-    @server.closed?.should be_false
+    @server.closed?.should == false
   end
 
   it "does not prevent reading" do
@@ -34,15 +34,15 @@ describe "Socket::BasicSocket#close_write" do
   it "fully closes the socket if it was already closed for reading" do
     @server.close_read
     @server.close_write
-    @server.closed?.should be_true
+    @server.closed?.should == true
   end
 
   it 'raises IOError when called on a fully closed socket' do
     @server.close
-    -> { @server.close_write }.should raise_error(IOError)
+    -> { @server.close_write }.should.raise(IOError)
   end
 
   it "returns nil" do
-    @server.close_write.should be_nil
+    @server.close_write.should == nil
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/connect_address_spec.rb b/spec/ruby/library/socket/basicsocket/connect_address_spec.rb
index 1a1c9982d9..e330b6e1be 100644
--- a/spec/ruby/library/socket/basicsocket/connect_address_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/connect_address_spec.rb
@@ -10,7 +10,7 @@ describe 'Socket#connect_address' do
     it 'raises SocketError' do
       @sock = Socket.new(:INET, :STREAM)
 
-      -> { @sock.connect_address }.should raise_error(SocketError)
+      -> { @sock.connect_address }.should.raise(SocketError)
     end
   end
 
@@ -25,7 +25,7 @@ describe 'Socket#connect_address' do
     end
 
     it 'returns an Addrinfo' do
-      @sock.connect_address.should be_an_instance_of(Addrinfo)
+      @sock.connect_address.should.instance_of?(Addrinfo)
     end
 
     it 'uses 127.0.0.1 as the IP address' do
@@ -65,7 +65,7 @@ describe 'Socket#connect_address' do
       end
 
       it 'returns an Addrinfo' do
-        @sock.connect_address.should be_an_instance_of(Addrinfo)
+        @sock.connect_address.should.instance_of?(Addrinfo)
       end
 
       it 'uses ::1 as the IP address' do
@@ -94,61 +94,59 @@ describe 'Socket#connect_address' do
     end
   end
 
-  with_feature :unix_socket do
-    platform_is_not :aix do
-      describe 'using an unbound UNIX socket' do
-        before do
-          @path = SocketSpecs.socket_path
-          @server = UNIXServer.new(@path)
-          @client = UNIXSocket.new(@path)
-        end
-
-        after do
-          @client.close
-          @server.close
-          rm_r(@path)
-        end
-
-        it 'raises SocketError' do
-          -> { @client.connect_address }.should raise_error(SocketError)
-        end
-      end
-    end
-
-    describe 'using a bound UNIX socket' do
+  platform_is_not :aix do
+    describe 'using an unbound UNIX socket' do
       before do
         @path = SocketSpecs.socket_path
-        @sock = UNIXServer.new(@path)
+        @server = UNIXServer.new(@path)
+        @client = UNIXSocket.new(@path)
       end
 
       after do
-        @sock.close
+        @client.close
+        @server.close
         rm_r(@path)
       end
 
-      it 'returns an Addrinfo' do
-        @sock.connect_address.should be_an_instance_of(Addrinfo)
+      it 'raises SocketError' do
+        -> { @client.connect_address }.should.raise(SocketError)
       end
+    end
+  end
 
-      it 'uses the correct socket path' do
-        @sock.connect_address.unix_path.should == @path
-      end
+  describe 'using a bound UNIX socket' do
+    before do
+      @path = SocketSpecs.socket_path
+      @sock = UNIXServer.new(@path)
+    end
 
-      it 'uses AF_UNIX as the address family' do
-        @sock.connect_address.afamily.should == Socket::AF_UNIX
-      end
+    after do
+      @sock.close
+      rm_r(@path)
+    end
 
-      it 'uses PF_UNIX as the protocol family' do
-        @sock.connect_address.pfamily.should == Socket::PF_UNIX
-      end
+    it 'returns an Addrinfo' do
+      @sock.connect_address.should.instance_of?(Addrinfo)
+    end
 
-      it 'uses SOCK_STREAM as the socket type' do
-        @sock.connect_address.socktype.should == Socket::SOCK_STREAM
-      end
+    it 'uses the correct socket path' do
+      @sock.connect_address.unix_path.should == @path
+    end
 
-      it 'uses 0 as the protocol' do
-        @sock.connect_address.protocol.should == 0
-      end
+    it 'uses AF_UNIX as the address family' do
+      @sock.connect_address.afamily.should == Socket::AF_UNIX
+    end
+
+    it 'uses PF_UNIX as the protocol family' do
+      @sock.connect_address.pfamily.should == Socket::PF_UNIX
+    end
+
+    it 'uses SOCK_STREAM as the socket type' do
+      @sock.connect_address.socktype.should == Socket::SOCK_STREAM
+    end
+
+    it 'uses 0 as the protocol' do
+      @sock.connect_address.protocol.should == 0
     end
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/do_not_reverse_lookup_spec.rb b/spec/ruby/library/socket/basicsocket/do_not_reverse_lookup_spec.rb
index a8800a8493..36338bfd59 100644
--- a/spec/ruby/library/socket/basicsocket/do_not_reverse_lookup_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/do_not_reverse_lookup_spec.rb
@@ -16,7 +16,7 @@ describe "BasicSocket.do_not_reverse_lookup" do
   end
 
   it "defaults to true" do
-    BasicSocket.do_not_reverse_lookup.should be_true
+    BasicSocket.do_not_reverse_lookup.should == true
   end
 
   it "causes 'peeraddr' to avoid name lookups" do
diff --git a/spec/ruby/library/socket/basicsocket/for_fd_spec.rb b/spec/ruby/library/socket/basicsocket/for_fd_spec.rb
index 9c9e6a8b55..8d5b71cfa9 100644
--- a/spec/ruby/library/socket/basicsocket/for_fd_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/for_fd_spec.rb
@@ -15,7 +15,7 @@ describe "BasicSocket.for_fd" do
   it "return a Socket instance wrapped around the descriptor" do
     @s2 = TCPServer.for_fd(@server.fileno)
     @s2.autoclose = false
-    @s2.should be_kind_of(TCPServer)
+    @s2.should.is_a?(TCPServer)
     @s2.fileno.should == @server.fileno
   end
 
@@ -24,7 +24,7 @@ describe "BasicSocket.for_fd" do
     socket2 = Socket.for_fd(@socket1.fileno)
     socket2.autoclose = false
 
-    socket2.should be_an_instance_of(Socket)
+    socket2.should.instance_of?(Socket)
     socket2.fileno.should == @socket1.fileno
   end
 
@@ -33,6 +33,6 @@ describe "BasicSocket.for_fd" do
     socket2 = Socket.for_fd(@socket1.fileno)
     socket2.autoclose = false
 
-    socket2.binmode?.should be_true
+    socket2.binmode?.should == true
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/getpeereid_spec.rb b/spec/ruby/library/socket/basicsocket/getpeereid_spec.rb
index 6179211d96..b9851bae15 100644
--- a/spec/ruby/library/socket/basicsocket/getpeereid_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/getpeereid_spec.rb
@@ -2,7 +2,7 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe 'BasicSocket#getpeereid' do
-  with_feature :unix_socket do
+  platform_is_not :windows do
     describe 'using a UNIXSocket' do
       before do
         @path = SocketSpecs.socket_path
@@ -30,7 +30,7 @@ describe 'BasicSocket#getpeereid' do
 
     it 'raises NoMethodError' do
       @sock = TCPServer.new('127.0.0.1', 0)
-      -> { @sock.getpeereid }.should raise_error(NoMethodError)
+      -> { @sock.getpeereid }.should.raise(NoMethodError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/getpeername_spec.rb b/spec/ruby/library/socket/basicsocket/getpeername_spec.rb
index 0b93f02eef..7e2f6f2e7b 100644
--- a/spec/ruby/library/socket/basicsocket/getpeername_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/getpeername_spec.rb
@@ -20,6 +20,6 @@ describe "Socket::BasicSocket#getpeername" do
   end
 
   it 'raises Errno::ENOTCONN for a disconnected socket' do
-    -> { @server.getpeername }.should raise_error(Errno::ENOTCONN)
+    -> { @server.getpeername }.should.raise(Errno::ENOTCONN)
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/getsockname_spec.rb b/spec/ruby/library/socket/basicsocket/getsockname_spec.rb
index b33db088b6..a54626647e 100644
--- a/spec/ruby/library/socket/basicsocket/getsockname_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/getsockname_spec.rb
@@ -3,7 +3,7 @@ require_relative '../fixtures/classes'
 
 describe "Socket::BasicSocket#getsockname" do
   after :each do
-    @socket.closed?.should be_false
+    @socket.closed?.should == false
     @socket.close
   end
 
@@ -16,7 +16,7 @@ describe "Socket::BasicSocket#getsockname" do
   it "works on sockets listening in ipaddr_any" do
     @socket = TCPServer.new(0)
     sockaddr = Socket.unpack_sockaddr_in(@socket.getsockname)
-    ["::", "0.0.0.0", "::ffff:0.0.0.0"].include?(sockaddr[1]).should be_true
+    ["::", "0.0.0.0", "::ffff:0.0.0.0"].include?(sockaddr[1]).should == true
     sockaddr[0].should == @socket.addr[1]
   end
 
diff --git a/spec/ruby/library/socket/basicsocket/getsockopt_spec.rb b/spec/ruby/library/socket/basicsocket/getsockopt_spec.rb
index ce65d6c92b..744297ad02 100644
--- a/spec/ruby/library/socket/basicsocket/getsockopt_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/getsockopt_spec.rb
@@ -7,7 +7,7 @@ describe "BasicSocket#getsockopt" do
   end
 
   after :each do
-    @sock.closed?.should be_false
+    @sock.closed?.should == false
     @sock.close
   end
 
@@ -41,13 +41,13 @@ describe "BasicSocket#getsockopt" do
   end
 
   it "raises a SystemCallError with an invalid socket option" do
-    -> { @sock.getsockopt Socket::SOL_SOCKET, -1 }.should raise_error(Errno::ENOPROTOOPT)
+    -> { @sock.getsockopt Socket::SOL_SOCKET, -1 }.should.raise(Errno::ENOPROTOOPT)
   end
 
   it 'returns a Socket::Option using a constant' do
     opt = @sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_TYPE)
 
-    opt.should be_an_instance_of(Socket::Option)
+    opt.should.instance_of?(Socket::Option)
   end
 
   it 'returns a Socket::Option for a boolean option' do
@@ -59,7 +59,7 @@ describe "BasicSocket#getsockopt" do
   it 'returns a Socket::Option for a numeric option' do
     opt = @sock.getsockopt(Socket::IPPROTO_IP, Socket::IP_TTL)
 
-    opt.int.should be_kind_of(Integer)
+    opt.int.should.is_a?(Integer)
   end
 
   it 'returns a Socket::Option for a struct option' do
@@ -69,7 +69,7 @@ describe "BasicSocket#getsockopt" do
   end
 
   it 'raises Errno::ENOPROTOOPT when requesting an invalid option' do
-    -> { @sock.getsockopt(Socket::SOL_SOCKET, -1) }.should raise_error(Errno::ENOPROTOOPT)
+    -> { @sock.getsockopt(Socket::SOL_SOCKET, -1) }.should.raise(Errno::ENOPROTOOPT)
   end
 
   describe 'using Symbols as arguments' do
@@ -171,7 +171,7 @@ describe "BasicSocket#getsockopt" do
       opt   = @sock.getsockopt(Socket::IPPROTO_IP, Socket::IP_TTL).to_s
       array = opt.unpack('i')
 
-      array[0].should be_kind_of(Integer)
+      array[0].should.is_a?(Integer)
       array[0].should > 0
     end
 
diff --git a/spec/ruby/library/socket/basicsocket/local_address_spec.rb b/spec/ruby/library/socket/basicsocket/local_address_spec.rb
new file mode 100644
index 0000000000..0bd60a44cd
--- /dev/null
+++ b/spec/ruby/library/socket/basicsocket/local_address_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../spec_helper'
+require_relative '../shared/address'
+
+describe 'BasicSocket#local_address' do
+  it_behaves_like :socket_local_remote_address, :local_address, -> socket {
+    a2 = BasicSocket.for_fd(socket.fileno)
+    a2.autoclose = false
+    a2.local_address
+  }
+end
diff --git a/spec/ruby/library/socket/basicsocket/read_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/read_nonblock_spec.rb
new file mode 100644
index 0000000000..ea5e65da5c
--- /dev/null
+++ b/spec/ruby/library/socket/basicsocket/read_nonblock_spec.rb
@@ -0,0 +1,74 @@
+require_relative '../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "BasicSocket#read_nonblock" do
+  SocketSpecs.each_ip_protocol do |family, ip_address|
+    before :each do
+      @r = Socket.new(family, :DGRAM)
+      @w = Socket.new(family, :DGRAM)
+
+      @r.bind(Socket.pack_sockaddr_in(0, ip_address))
+      @w.send("aaa", 0, @r.getsockname)
+    end
+
+    after :each do
+      @r.close unless @r.closed?
+      @w.close unless @w.closed?
+    end
+
+    it "receives data after it's ready" do
+      IO.select([@r], nil, nil, 2)
+      @r.read_nonblock(5).should == "aaa"
+    end
+
+    platform_is_not :windows do
+      it 'returned data is binary encoded regardless of the external encoding' do
+        IO.select([@r], nil, nil, 2)
+        @r.read_nonblock(1).encoding.should == Encoding::BINARY
+
+        @w.send("bbb", 0, @r.getsockname)
+        @r.set_encoding(Encoding::ISO_8859_1)
+        IO.select([@r], nil, nil, 2)
+        buffer = @r.read_nonblock(3)
+        buffer.should == "bbb"
+        buffer.encoding.should == Encoding::BINARY
+      end
+    end
+
+    it 'replaces the content of the provided buffer without changing its encoding' do
+      buffer = "initial data".dup.force_encoding(Encoding::UTF_8)
+
+      IO.select([@r], nil, nil, 2)
+      @r.read_nonblock(3, buffer)
+      buffer.should == "aaa"
+      buffer.encoding.should == Encoding::UTF_8
+
+      @w.send("bbb", 0, @r.getsockname)
+      @r.set_encoding(Encoding::ISO_8859_1)
+      IO.select([@r], nil, nil, 2)
+      @r.read_nonblock(3, buffer)
+      buffer.should == "bbb"
+      buffer.encoding.should == Encoding::UTF_8
+    end
+
+    platform_is :linux do
+      it 'does not set the IO in nonblock mode' do
+        require 'io/nonblock'
+        @r.nonblock = false
+        IO.select([@r], nil, nil, 2)
+        @r.read_nonblock(3).should == "aaa"
+        @r.should_not.nonblock?
+      end
+    end
+
+    platform_is_not :linux, :windows do
+      it 'sets the IO in nonblock mode' do
+        require 'io/nonblock'
+        @r.nonblock = false
+        IO.select([@r], nil, nil, 2)
+        @r.read_nonblock(3).should == "aaa"
+        @r.should.nonblock?
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/basicsocket/read_spec.rb b/spec/ruby/library/socket/basicsocket/read_spec.rb
new file mode 100644
index 0000000000..ba9de7d5cf
--- /dev/null
+++ b/spec/ruby/library/socket/basicsocket/read_spec.rb
@@ -0,0 +1,47 @@
+require_relative '../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "BasicSocket#read" do
+  SocketSpecs.each_ip_protocol do |family, ip_address|
+    before :each do
+      @r = Socket.new(family, :DGRAM)
+      @w = Socket.new(family, :DGRAM)
+
+      @r.bind(Socket.pack_sockaddr_in(0, ip_address))
+      @w.send("aaa", 0, @r.getsockname)
+    end
+
+    after :each do
+      @r.close unless @r.closed?
+      @w.close unless @w.closed?
+    end
+
+    it "receives data after it's ready" do
+      @r.read(3).should == "aaa"
+    end
+
+    it 'returned data is binary encoded regardless of the external encoding' do
+      @r.read(3).encoding.should == Encoding::BINARY
+
+      @w.send("bbb", 0, @r.getsockname)
+      @r.set_encoding(Encoding::UTF_8)
+      buffer = @r.read(3)
+      buffer.should == "bbb"
+      buffer.encoding.should == Encoding::BINARY
+    end
+
+    it 'replaces the content of the provided buffer without changing its encoding' do
+      buffer = "initial data".dup.force_encoding(Encoding::UTF_8)
+
+      @r.read(3, buffer)
+      buffer.should == "aaa"
+      buffer.encoding.should == Encoding::UTF_8
+
+      @w.send("bbb", 0, @r.getsockname)
+      @r.set_encoding(Encoding::ISO_8859_1)
+      @r.read(3, buffer)
+      buffer.should == "bbb"
+      buffer.encoding.should == Encoding::UTF_8
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
index 0363f2f8de..8aca7d0332 100644
--- a/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
@@ -16,7 +16,7 @@ describe "Socket::BasicSocket#recv_nonblock" do
     platform_is_not :windows do
       describe 'using an unbound socket' do
         it 'raises an exception extending IO::WaitReadable' do
-          -> { @s1.recv_nonblock(1) }.should raise_error(IO::WaitReadable)
+          -> { @s1.recv_nonblock(1) }.should.raise(IO::WaitReadable)
         end
       end
     end
@@ -25,12 +25,12 @@ describe "Socket::BasicSocket#recv_nonblock" do
       @s1.bind(Socket.pack_sockaddr_in(0, ip_address))
       -> {
         @s1.recv_nonblock(5)
-      }.should raise_error(IO::WaitReadable) { |e|
+      }.should.raise(IO::WaitReadable) { |e|
         platform_is_not :windows do
-          e.should be_kind_of(Errno::EAGAIN)
+          e.should.is_a?(Errno::EAGAIN)
         end
         platform_is :windows do
-          e.should be_kind_of(Errno::EWOULDBLOCK)
+          e.should.is_a?(Errno::EWOULDBLOCK)
         end
       }
     end
@@ -52,9 +52,19 @@ describe "Socket::BasicSocket#recv_nonblock" do
       @s2.send("data", 0, @s1.getsockname)
       IO.select([@s1], nil, nil, 2)
 
-      buf = "foo"
-      @s1.recv_nonblock(5, 0, buf)
-      buf.should == "data"
+      buffer = +"foo"
+      @s1.recv_nonblock(5, 0, buffer).should.equal?(buffer)
+      buffer.should == "data"
+    end
+
+    it "preserves the encoding of the given buffer" do
+      @s1.bind(Socket.pack_sockaddr_in(0, ip_address))
+      @s2.send("data", 0, @s1.getsockname)
+      IO.select([@s1], nil, nil, 2)
+
+      buffer = ''.encode(Encoding::ISO_8859_1)
+      @s1.recv_nonblock(5, 0, buffer)
+      buffer.encoding.should == Encoding::ISO_8859_1
     end
 
     it "does not block if there's no data available" do
@@ -64,7 +74,69 @@ describe "Socket::BasicSocket#recv_nonblock" do
       @s1.recv_nonblock(1).should == "a"
       -> {
         @s1.recv_nonblock(5)
-      }.should raise_error(IO::WaitReadable)
+      }.should.raise(IO::WaitReadable)
+    end
+  end
+
+  SocketSpecs.each_ip_protocol do |family, ip_address|
+    describe 'using a connected but not bound socket' do
+      before do
+        @server = Socket.new(family, :STREAM)
+      end
+
+      after do
+        @server.close
+      end
+
+      it "raises Errno::ENOTCONN" do
+        -> { @server.recv_nonblock(1) }.should.raise { |e|
+          [Errno::ENOTCONN, Errno::EINVAL].should.include?(e.class)
+        }
+        -> { @server.recv_nonblock(1, exception: false) }.should.raise { |e|
+          [Errno::ENOTCONN, Errno::EINVAL].should.include?(e.class)
+        }
+      end
+    end
+  end
+end
+
+describe "Socket::BasicSocket#recv_nonblock" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      it "returns nil on a closed stream socket" do
+        ready = false
+
+        t = Thread.new do
+          client = @server.accept
+
+          Thread.pass while !ready
+          begin
+            client.recv_nonblock(10)
+          rescue IO::EAGAINWaitReadable
+            retry
+          end
+        ensure
+          client.close if client
+        end
+
+        Thread.pass while t.status and t.status != "sleep"
+        t.status.should_not == nil
+
+        socket = TCPSocket.new('127.0.0.1', @port)
+        socket.close
+        ready = true
+
+        t.value.should == nil
+      end
     end
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/recv_spec.rb b/spec/ruby/library/socket/basicsocket/recv_spec.rb
index b6ccda5d00..5c393218bc 100644
--- a/spec/ruby/library/socket/basicsocket/recv_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recv_spec.rb
@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
@@ -22,7 +22,7 @@ describe "BasicSocket#recv" do
       client.close
     end
     Thread.pass while t.status and t.status != "sleep"
-    t.status.should_not be_nil
+    t.status.should_not == nil
 
     socket = TCPSocket.new('127.0.0.1', @port)
     socket.send('hello', 0)
@@ -32,28 +32,26 @@ describe "BasicSocket#recv" do
     ScratchPad.recorded.should == 'hello'
   end
 
-  platform_is_not :solaris do
-    it "accepts flags to specify unusual receiving behaviour" do
-      t = Thread.new do
-        client = @server.accept
+  it "accepts flags to specify unusual receiving behaviour" do
+    t = Thread.new do
+      client = @server.accept
 
-        # in-band data (TCP), doesn't receive the flag.
-        ScratchPad.record client.recv(10)
+      # in-band data (TCP), doesn't receive the flag.
+      ScratchPad.record client.recv(10)
 
-        # this recv is important (TODO: explain)
-        client.recv(10)
-        client.close
-      end
-      Thread.pass while t.status and t.status != "sleep"
-      t.status.should_not be_nil
-
-      socket = TCPSocket.new('127.0.0.1', @port)
-      socket.send('helloU', Socket::MSG_OOB)
-      socket.shutdown(1)
-      t.join
-      socket.close
-      ScratchPad.recorded.should == 'hello'
+      # this recv is important (TODO: explain)
+      client.recv(10)
+      client.close
     end
+    Thread.pass while t.status and t.status != "sleep"
+    t.status.should_not == nil
+
+    socket = TCPSocket.new('127.0.0.1', @port)
+    socket.send('helloU', Socket::MSG_OOB)
+    socket.shutdown(1)
+    t.join
+    socket.close
+    ScratchPad.recorded.should == 'hello'
   end
 
   it "gets lines delimited with a custom separator"  do
@@ -66,7 +64,7 @@ describe "BasicSocket#recv" do
       client.close
     end
     Thread.pass while t.status and t.status != "sleep"
-    t.status.should_not be_nil
+    t.status.should_not == nil
 
     socket = TCPSocket.new('127.0.0.1', @port)
     socket.write("firstline\377secondline\377")
@@ -81,13 +79,29 @@ describe "BasicSocket#recv" do
     socket.write("data")
 
     client = @server.accept
-    buf = "foo"
+    buffer = +"foo"
+    begin
+      client.recv(4, 0, buffer).should.equal?(buffer)
+    ensure
+      client.close
+    end
+    buffer.should == "data"
+
+    socket.close
+  end
+
+  it "preserves the encoding of the given buffer" do
+    socket = TCPSocket.new('127.0.0.1', @port)
+    socket.write("data")
+
+    client = @server.accept
+    buffer = ''.encode(Encoding::ISO_8859_1)
     begin
-      client.recv(4, 0, buf)
+      client.recv(4, 0, buffer)
     ensure
       client.close
     end
-    buf.should == "data"
+    buffer.encoding.should == Encoding::ISO_8859_1
 
     socket.close
   end
@@ -157,3 +171,59 @@ describe 'BasicSocket#recv' do
     end
   end
 end
+
+describe "BasicSocket#recv" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      it "returns nil on a closed stream socket" do
+        t = Thread.new do
+          client = @server.accept
+          client.recv(10)
+        ensure
+          client.close if client
+        end
+
+        Thread.pass while t.status and t.status != "sleep"
+        t.status.should_not == nil
+
+        socket = TCPSocket.new('127.0.0.1', @port)
+        socket.close
+
+        t.value.should == nil
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns empty String" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+
+          @server.recv(1).should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
index 8e6c232c59..9d77f5df6b 100644
--- a/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
@@ -17,7 +17,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
       platform_is_not :windows do
         describe 'using an unbound socket' do
           it 'raises an exception extending IO::WaitReadable' do
-            -> { @server.recvmsg_nonblock }.should raise_error(IO::WaitReadable)
+            -> { @server.recvmsg_nonblock }.should.raise(IO::WaitReadable)
           end
         end
       end
@@ -29,7 +29,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
 
         describe 'without any data available' do
           it 'raises an exception extending IO::WaitReadable' do
-            -> { @server.recvmsg_nonblock }.should raise_error(IO::WaitReadable)
+            -> { @server.recvmsg_nonblock }.should.raise(IO::WaitReadable)
           end
 
           it 'returns :wait_readable with exception: false' do
@@ -47,7 +47,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
           end
 
           it 'returns an Array containing the data, an Addrinfo and the flags' do
-            @server.recvmsg_nonblock.should be_an_instance_of(Array)
+            @server.recvmsg_nonblock.should.instance_of?(Array)
           end
 
           describe 'without a maximum message length' do
@@ -74,12 +74,12 @@ describe 'BasicSocket#recvmsg_nonblock' do
             end
 
             it 'stores an Addrinfo at index 1' do
-              @array[1].should be_an_instance_of(Addrinfo)
+              @array[1].should.instance_of?(Addrinfo)
             end
 
             platform_is_not :windows do
               it 'stores the flags at index 2' do
-                @array[2].should be_kind_of(Integer)
+                @array[2].should.is_a?(Integer)
               end
             end
 
@@ -114,6 +114,21 @@ describe 'BasicSocket#recvmsg_nonblock' do
     end
 
     platform_is_not :windows do
+      describe 'using a connected but not bound socket' do
+        before do
+          @server = Socket.new(family, :STREAM)
+        end
+
+        after do
+          @server.close
+        end
+
+        it "raises Errno::ENOTCONN" do
+          -> { @server.recvmsg_nonblock }.should.raise(Errno::ENOTCONN)
+          -> { @server.recvmsg_nonblock(exception: false) }.should.raise(Errno::ENOTCONN)
+        end
+      end
+
       describe 'using a connected socket' do
         before do
           @client = Socket.new(family, :STREAM)
@@ -139,7 +154,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
               ensure
                 socket.close
               end
-            }.should raise_error(IO::WaitReadable)
+            }.should.raise(IO::WaitReadable)
           end
         end
 
@@ -156,7 +171,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
           end
 
           it 'returns an Array containing the data, an Addrinfo and the flags' do
-            @socket.recvmsg_nonblock.should be_an_instance_of(Array)
+            @socket.recvmsg_nonblock.should.instance_of?(Array)
           end
 
           describe 'the returned Array' do
@@ -169,11 +184,11 @@ describe 'BasicSocket#recvmsg_nonblock' do
             end
 
             it 'stores an Addrinfo at index 1' do
-              @array[1].should be_an_instance_of(Addrinfo)
+              @array[1].should.instance_of?(Addrinfo)
             end
 
             it 'stores the flags at index 2' do
-              @array[2].should be_kind_of(Integer)
+              @array[2].should.is_a?(Integer)
             end
 
             describe 'the returned Addrinfo' do
@@ -182,7 +197,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
               end
 
               it 'raises when receiving the ip_address message' do
-                -> { @addr.ip_address }.should raise_error(SocketError)
+                -> { @addr.ip_address }.should.raise(SocketError)
               end
 
               it 'uses the correct address family' do
@@ -198,7 +213,7 @@ describe 'BasicSocket#recvmsg_nonblock' do
               end
 
               it 'raises when receiving the ip_port message' do
-                -> { @addr.ip_port }.should raise_error(SocketError)
+                -> { @addr.ip_port }.should.raise(SocketError)
               end
             end
           end
@@ -207,3 +222,46 @@ describe 'BasicSocket#recvmsg_nonblock' do
     end
   end
 end
+
+describe 'BasicSocket#recvmsg_nonblock' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      platform_is_not :windows do
+        it "returns nil on a closed stream socket" do
+          ready = false
+
+          t = Thread.new do
+            client = @server.accept
+
+            Thread.pass while !ready
+            begin
+              client.recvmsg_nonblock(10)
+            rescue IO::EAGAINWaitReadable
+              retry
+            end
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not == nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+          ready = true
+
+          t.value.should == nil
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/basicsocket/recvmsg_spec.rb b/spec/ruby/library/socket/basicsocket/recvmsg_spec.rb
index 8063723701..eabfb9dd18 100644
--- a/spec/ruby/library/socket/basicsocket/recvmsg_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recvmsg_spec.rb
@@ -41,7 +41,7 @@ describe 'BasicSocket#recvmsg' do
           end
 
           it 'returns an Array containing the data, an Addrinfo and the flags' do
-            @server.recvmsg.should be_an_instance_of(Array)
+            @server.recvmsg.should.instance_of?(Array)
           end
 
           describe 'without a maximum message length' do
@@ -66,12 +66,12 @@ describe 'BasicSocket#recvmsg' do
             end
 
             it 'stores an Addrinfo at index 1' do
-              @array[1].should be_an_instance_of(Addrinfo)
+              @array[1].should.instance_of?(Addrinfo)
             end
 
             platform_is_not :windows do
               it 'stores the flags at index 2' do
-                @array[2].should be_kind_of(Integer)
+                @array[2].should.is_a?(Integer)
               end
             end
 
@@ -144,7 +144,7 @@ describe 'BasicSocket#recvmsg' do
           end
 
           it 'returns an Array containing the data, an Addrinfo and the flags' do
-            @socket.recvmsg.should be_an_instance_of(Array)
+            @socket.recvmsg.should.instance_of?(Array)
           end
 
           describe 'the returned Array' do
@@ -157,11 +157,11 @@ describe 'BasicSocket#recvmsg' do
             end
 
             it 'stores an Addrinfo at index 1' do
-              @array[1].should be_an_instance_of(Addrinfo)
+              @array[1].should.instance_of?(Addrinfo)
             end
 
             it 'stores the flags at index 2' do
-              @array[2].should be_kind_of(Integer)
+              @array[2].should.is_a?(Integer)
             end
 
             describe 'the returned Addrinfo' do
@@ -170,7 +170,7 @@ describe 'BasicSocket#recvmsg' do
               end
 
               it 'raises when receiving the ip_address message' do
-                -> { @addr.ip_address }.should raise_error(SocketError)
+                -> { @addr.ip_address }.should.raise(SocketError)
               end
 
               it 'uses the correct address family' do
@@ -186,7 +186,7 @@ describe 'BasicSocket#recvmsg' do
               end
 
               it 'raises when receiving the ip_port message' do
-                -> { @addr.ip_port }.should raise_error(SocketError)
+                -> { @addr.ip_port }.should.raise(SocketError)
               end
             end
           end
@@ -195,3 +195,63 @@ describe 'BasicSocket#recvmsg' do
     end
   end
 end
+
+describe 'BasicSocket#recvmsg' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new('127.0.0.1', 0)
+        @port = @server.addr[1]
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+      end
+
+      platform_is_not :windows do
+        it "returns nil on a closed stream socket" do
+          t = Thread.new do
+            client = @server.accept
+            client.recvmsg(10)
+          ensure
+            client.close if client
+          end
+
+          Thread.pass while t.status and t.status != "sleep"
+          t.status.should_not == nil
+
+          socket = TCPSocket.new('127.0.0.1', @port)
+          socket.close
+
+          t.value.should == nil
+        end
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+          message = @server.recvmsg(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/basicsocket/remote_address_spec.rb b/spec/ruby/library/socket/basicsocket/remote_address_spec.rb
new file mode 100644
index 0000000000..439bf31592
--- /dev/null
+++ b/spec/ruby/library/socket/basicsocket/remote_address_spec.rb
@@ -0,0 +1,10 @@
+require_relative '../spec_helper'
+require_relative '../shared/address'
+
+describe 'BasicSocket#remote_address' do
+  it_behaves_like :socket_local_remote_address, :remote_address, -> socket {
+    a2 = BasicSocket.for_fd(socket.fileno)
+    a2.autoclose = false
+    a2.remote_address
+  }
+end
diff --git a/spec/ruby/library/socket/basicsocket/send_spec.rb b/spec/ruby/library/socket/basicsocket/send_spec.rb
index 041ee46998..a2c2ee8de9 100644
--- a/spec/ruby/library/socket/basicsocket/send_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/send_spec.rb
@@ -9,36 +9,36 @@ describe "BasicSocket#send" do
   end
 
   after :each do
-    @server.closed?.should be_false
-    @socket.closed?.should be_false
+    @server.closed?.should == false
+    @socket.closed?.should == false
 
     @server.close
     @socket.close
   end
 
-   it "sends a message to another socket and returns the number of bytes sent" do
-     data = ""
-     t = Thread.new do
-       client = @server.accept
-       loop do
-         got = client.recv(5)
-         break if got.empty?
-         data << got
-       end
-       client.close
-     end
-     Thread.pass while t.status and t.status != "sleep"
-     t.status.should_not be_nil
-
-     @socket.send('hello', 0).should == 5
-     @socket.shutdown(1) # indicate, that we are done sending
-     @socket.recv(10)
-
-     t.join
-     data.should == 'hello'
-   end
-
-  platform_is_not :solaris, :windows do
+  it "sends a message to another socket and returns the number of bytes sent" do
+    data = +""
+    t = Thread.new do
+      client = @server.accept
+      loop do
+        got = client.recv(5)
+        break if got.nil? || got.empty?
+        data << got
+      end
+      client.close
+    end
+    Thread.pass while t.status and t.status != "sleep"
+    t.status.should_not == nil
+
+    @socket.send('hello', 0).should == 5
+    @socket.shutdown(1) # indicate, that we are done sending
+    @socket.recv(10)
+
+    t.join
+    data.should == 'hello'
+  end
+
+  platform_is_not :windows do
     it "accepts flags to specify unusual sending behaviour" do
       data = nil
       peek_data = nil
@@ -50,7 +50,7 @@ describe "BasicSocket#send" do
         client.close
       end
       Thread.pass while t.status and t.status != "sleep"
-      t.status.should_not be_nil
+      t.status.should_not == nil
 
       @socket.send('helloU', Socket::MSG_PEEK | Socket::MSG_OOB).should == 6
       @socket.shutdown # indicate, that we are done sending
@@ -62,25 +62,25 @@ describe "BasicSocket#send" do
   end
 
   it "accepts a sockaddr as recipient address" do
-     data = ""
-     t = Thread.new do
-       client = @server.accept
-       loop do
-         got = client.recv(5)
-         break if got.empty?
-         data << got
-       end
-       client.close
-     end
-     Thread.pass while t.status and t.status != "sleep"
-     t.status.should_not be_nil
-
-     sockaddr = Socket.pack_sockaddr_in(@port, "127.0.0.1")
-     @socket.send('hello', 0, sockaddr).should == 5
-     @socket.shutdown # indicate, that we are done sending
-
-     t.join
-     data.should == 'hello'
+    data = +""
+    t = Thread.new do
+      client = @server.accept
+      loop do
+        got = client.recv(5)
+        break if got.nil? || got.empty?
+        data << got
+      end
+      client.close
+    end
+    Thread.pass while t.status and t.status != "sleep"
+    t.status.should_not == nil
+
+    sockaddr = Socket.pack_sockaddr_in(@port, "127.0.0.1")
+    @socket.send('hello', 0, sockaddr).should == 5
+    @socket.shutdown # indicate, that we are done sending
+
+    t.join
+    data.should == 'hello'
   end
 end
 
@@ -99,9 +99,17 @@ describe 'BasicSocket#send' do
         @server.close
       end
 
+      describe 'with an object implementing #to_str' do
+        it 'returns the amount of sent bytes' do
+          data = mock('message')
+          data.should_receive(:to_str).and_return('hello')
+          @client.send(data, 0, @server.getsockname).should == 5
+        end
+      end
+
       describe 'without a destination address' do
         it "raises #{SocketSpecs.dest_addr_req_error}" do
-          -> { @client.send('hello', 0) }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> { @client.send('hello', 0) }.should.raise(SocketSpecs.dest_addr_req_error)
         end
       end
 
@@ -113,7 +121,7 @@ describe 'BasicSocket#send' do
         it 'does not persist the connection after writing to the socket' do
           @client.send('hello', 0, @server.getsockname)
 
-          -> { @client.send('hello', 0) }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> { @client.send('hello', 0) }.should.raise(SocketSpecs.dest_addr_req_error)
         end
       end
 
diff --git a/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
index c112f2ab4a..4cd6e8bdca 100644
--- a/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
@@ -18,7 +18,12 @@ describe 'BasicSocket#sendmsg_nonblock' do
 
       describe 'without a destination address' do
         it "raises #{SocketSpecs.dest_addr_req_error}" do
-          -> { @client.sendmsg_nonblock('hello') }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> {
+            @client.sendmsg_nonblock('hello')
+          }.should.raise(SocketSpecs.dest_addr_req_error)
+          -> {
+            @client.sendmsg_nonblock('hello', exception: false)
+          }.should.raise(SocketSpecs.dest_addr_req_error)
         end
       end
 
@@ -96,7 +101,7 @@ describe 'BasicSocket#sendmsg_nonblock' do
         it 'raises IO::WaitWritable when the underlying buffer is full' do
           -> {
             10.times { @client.sendmsg_nonblock('hello' * 1_000_000) }
-          }.should raise_error(IO::WaitWritable)
+          }.should.raise(IO::WaitWritable)
         end
 
         it 'returns :wait_writable when the underlying buffer is full with exception: false' do
diff --git a/spec/ruby/library/socket/basicsocket/sendmsg_spec.rb b/spec/ruby/library/socket/basicsocket/sendmsg_spec.rb
index 7ff336c0b7..dc999b32df 100644
--- a/spec/ruby/library/socket/basicsocket/sendmsg_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/sendmsg_spec.rb
@@ -19,7 +19,7 @@ describe 'BasicSocket#sendmsg' do
       platform_is_not :windows do
         describe 'without a destination address' do
           it "raises #{SocketSpecs.dest_addr_req_error}" do
-            -> { @client.sendmsg('hello') }.should raise_error(SocketSpecs.dest_addr_req_error)
+            -> { @client.sendmsg('hello') }.should.raise(SocketSpecs.dest_addr_req_error)
           end
         end
       end
diff --git a/spec/ruby/library/socket/basicsocket/setsockopt_spec.rb b/spec/ruby/library/socket/basicsocket/setsockopt_spec.rb
index 1e8d84e1c9..e306581aa3 100644
--- a/spec/ruby/library/socket/basicsocket/setsockopt_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/setsockopt_spec.rb
@@ -40,7 +40,7 @@ describe "BasicSocket#setsockopt" do
     it "raises EINVAL if passed wrong linger value" do
       -> do
         @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_LINGER, 0)
-      end.should raise_error(Errno::EINVAL)
+      end.should.raise(Errno::EINVAL)
     end
   end
 
@@ -72,7 +72,7 @@ describe "BasicSocket#setsockopt" do
       platform_is_not :windows do
         -> {
           @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "")
-        }.should raise_error(SystemCallError)
+        }.should.raise(SystemCallError)
       end
 
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "blah").should == 0
@@ -82,7 +82,7 @@ describe "BasicSocket#setsockopt" do
       platform_is_not :windows do
         -> {
           @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "0")
-        }.should raise_error(SystemCallError)
+        }.should.raise(SystemCallError)
       end
 
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "\x00\x00\x00\x00").should == 0
@@ -92,13 +92,13 @@ describe "BasicSocket#setsockopt" do
       platform_is_not :windows do
         -> {
           @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "1")
-        }.should raise_error(SystemCallError)
+        }.should.raise(SystemCallError)
       end
 
       platform_is_not :windows do
         -> {
           @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, "\x00\x00\x00")
-        }.should raise_error(SystemCallError)
+        }.should.raise(SystemCallError)
       end
 
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_OOBINLINE, [1].pack('i')).should == 0
@@ -127,7 +127,7 @@ describe "BasicSocket#setsockopt" do
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, nil).should == 0
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
 
     @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, 1).should == 0
     n = @sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF).to_s
@@ -139,23 +139,23 @@ describe "BasicSocket#setsockopt" do
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "")
-    }.should raise_error(SystemCallError)
+    }.should.raise(SystemCallError)
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "bla")
-    }.should raise_error(SystemCallError)
+    }.should.raise(SystemCallError)
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "0")
-    }.should raise_error(SystemCallError)
+    }.should.raise(SystemCallError)
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "1")
-    }.should raise_error(SystemCallError)
+    }.should.raise(SystemCallError)
 
     -> {
       @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "\x00\x00\x00")
-    }.should raise_error(SystemCallError)
+    }.should.raise(SystemCallError)
 
     @sock.setsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF, "\x00\x00\x01\x00").should == 0
     n = @sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_SNDBUF).to_s
@@ -207,7 +207,7 @@ describe "BasicSocket#setsockopt" do
       onoff, seconds = @sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_LINGER).linger
       seconds.should == 10
       # Both results can be produced depending on the OS and value of Socket::SO_LINGER
-      [true, Socket::SO_LINGER].should include(onoff)
+      [true, Socket::SO_LINGER].should.include?(onoff)
     end
   end
 end
@@ -224,7 +224,7 @@ describe 'BasicSocket#setsockopt' do
 
     describe 'using separate arguments with Symbols' do
       it 'raises TypeError when the first argument is nil' do
-        -> { @socket.setsockopt(nil, :REUSEADDR, true) }.should raise_error(TypeError)
+        -> { @socket.setsockopt(nil, :REUSEADDR, true) }.should.raise(TypeError)
       end
 
       it 'sets a boolean option' do
@@ -251,7 +251,7 @@ describe 'BasicSocket#setsockopt' do
 
       platform_is_not :windows do
         it 'raises Errno::EINVAL when setting an invalid option value' do
-          -> { @socket.setsockopt(:SOCKET, :OOBINLINE, 'bla') }.should raise_error(Errno::EINVAL)
+          -> { @socket.setsockopt(:SOCKET, :OOBINLINE, 'bla') }.should.raise(Errno::EINVAL)
         end
       end
     end
@@ -305,32 +305,30 @@ describe 'BasicSocket#setsockopt' do
 
       it 'raises ArgumentError when passing 2 arguments' do
         option = Socket::Option.bool(:INET, :SOCKET, :REUSEADDR, true)
-        -> { @socket.setsockopt(option, :REUSEADDR) }.should raise_error(ArgumentError)
+        -> { @socket.setsockopt(option, :REUSEADDR) }.should.raise(ArgumentError)
       end
 
       it 'raises TypeError when passing 3 arguments' do
         option = Socket::Option.bool(:INET, :SOCKET, :REUSEADDR, true)
-        -> { @socket.setsockopt(option, :REUSEADDR, true) }.should raise_error(TypeError)
+        -> { @socket.setsockopt(option, :REUSEADDR, true) }.should.raise(TypeError)
       end
     end
   end
 
-  with_feature :unix_socket do
-    describe 'using a UNIX socket' do
-      before do
-        @path = SocketSpecs.socket_path
-        @server = UNIXServer.new(@path)
-      end
+  describe 'using a UNIX socket' do
+    before do
+      @path = SocketSpecs.socket_path
+      @server = UNIXServer.new(@path)
+    end
 
-      after do
-        @server.close
-        rm_r @path
-      end
+    after do
+      @server.close
+      rm_r @path
+    end
 
-      it 'sets a boolean option' do
-        @server.setsockopt(:SOCKET, :REUSEADDR, true)
-        @server.getsockopt(:SOCKET, :REUSEADDR).bool.should == true
-      end
+    it 'sets a boolean option' do
+      @server.setsockopt(:SOCKET, :REUSEADDR, true)
+      @server.getsockopt(:SOCKET, :REUSEADDR).bool.should == true
     end
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/shutdown_spec.rb b/spec/ruby/library/socket/basicsocket/shutdown_spec.rb
index 41d9581bde..c96c62abe1 100644
--- a/spec/ruby/library/socket/basicsocket/shutdown_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/shutdown_spec.rb
@@ -23,25 +23,25 @@ platform_is_not :windows do # hangs
         it 'shuts down a socket for reading' do
           @client.shutdown(Socket::SHUT_RD)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for writing' do
           @client.shutdown(Socket::SHUT_WR)
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'shuts down a socket for reading and writing' do
           @client.shutdown(Socket::SHUT_RDWR)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'raises ArgumentError when using an invalid option' do
-          -> { @server.shutdown(666) }.should raise_error(ArgumentError)
+          -> { @server.shutdown(666) }.should.raise(ArgumentError)
         end
       end
 
@@ -49,37 +49,37 @@ platform_is_not :windows do # hangs
         it 'shuts down a socket for reading using :RD' do
           @client.shutdown(:RD)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for reading using :SHUT_RD' do
           @client.shutdown(:SHUT_RD)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for writing using :WR' do
           @client.shutdown(:WR)
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'shuts down a socket for writing using :SHUT_WR' do
           @client.shutdown(:SHUT_WR)
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'shuts down a socket for reading and writing' do
           @client.shutdown(:RDWR)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'raises ArgumentError when using an invalid option' do
-          -> { @server.shutdown(:Nope) }.should raise_error(SocketError)
+          -> { @server.shutdown(:Nope) }.should.raise(SocketError)
         end
       end
 
@@ -87,29 +87,29 @@ platform_is_not :windows do # hangs
         it 'shuts down a socket for reading using "RD"' do
           @client.shutdown('RD')
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for reading using "SHUT_RD"' do
           @client.shutdown('SHUT_RD')
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for writing using "WR"' do
           @client.shutdown('WR')
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'shuts down a socket for writing using "SHUT_WR"' do
           @client.shutdown('SHUT_WR')
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
 
         it 'raises ArgumentError when using an invalid option' do
-          -> { @server.shutdown('Nope') }.should raise_error(SocketError)
+          -> { @server.shutdown('Nope') }.should.raise(SocketError)
         end
       end
 
@@ -123,7 +123,7 @@ platform_is_not :windows do # hangs
 
           @client.shutdown(@dummy)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for reading using "SHUT_RD"' do
@@ -131,7 +131,7 @@ platform_is_not :windows do # hangs
 
           @client.shutdown(@dummy)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
         end
 
         it 'shuts down a socket for reading and writing' do
@@ -139,15 +139,15 @@ platform_is_not :windows do # hangs
 
           @client.shutdown(@dummy)
 
-          @client.recv(1).should be_empty
+          @client.recv(1).to_s.should.empty?
 
-          -> { @client.write('hello') }.should raise_error(Errno::EPIPE)
+          -> { @client.write('hello') }.should.raise(Errno::EPIPE)
         end
       end
 
       describe 'using an object that does not respond to #to_str' do
         it 'raises TypeError' do
-          -> { @server.shutdown(mock(:dummy)) }.should raise_error(TypeError)
+          -> { @server.shutdown(mock(:dummy)) }.should.raise(TypeError)
         end
       end
     end
diff --git a/spec/ruby/library/socket/basicsocket/write_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/write_nonblock_spec.rb
new file mode 100644
index 0000000000..523e732959
--- /dev/null
+++ b/spec/ruby/library/socket/basicsocket/write_nonblock_spec.rb
@@ -0,0 +1,43 @@
+require_relative '../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "BasicSocket#write_nonblock" do
+  SocketSpecs.each_ip_protocol do |family, ip_address|
+    before :each do
+      @r = Socket.new(family, :DGRAM)
+      @w = Socket.new(family, :DGRAM)
+
+      @r.bind(Socket.pack_sockaddr_in(0, ip_address))
+      @w.connect(@r.getsockname)
+    end
+
+    after :each do
+      @r.close unless @r.closed?
+      @w.close unless @w.closed?
+    end
+
+    it "sends data" do
+      @w.write_nonblock("aaa").should == 3
+      IO.select([@r], nil, nil, 2)
+      @r.recv_nonblock(5).should == "aaa"
+    end
+
+    platform_is :linux do
+      it 'does not set the IO in nonblock mode' do
+        require 'io/nonblock'
+        @w.nonblock = false
+        @w.write_nonblock("aaa").should == 3
+        @w.should_not.nonblock?
+      end
+    end
+
+    platform_is_not :linux, :windows do
+      it 'sets the IO in nonblock mode' do
+        require 'io/nonblock'
+        @w.nonblock = false
+        @w.write_nonblock("aaa").should == 3
+        @w.should.nonblock?
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/constants/constants_spec.rb b/spec/ruby/library/socket/constants/constants_spec.rb
index 710af12828..a936473bb6 100644
--- a/spec/ruby/library/socket/constants/constants_spec.rb
+++ b/spec/ruby/library/socket/constants/constants_spec.rb
@@ -5,47 +5,47 @@ describe "Socket::Constants" do
   it "defines socket types" do
     consts = ["SOCK_DGRAM", "SOCK_RAW", "SOCK_RDM", "SOCK_SEQPACKET", "SOCK_STREAM"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
   it "defines protocol families" do
     consts = ["PF_INET6", "PF_INET", "PF_UNIX", "PF_UNSPEC"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
   platform_is_not :aix do
     it "defines PF_IPX protocol" do
-      Socket::Constants.should have_constant("PF_IPX")
+      Socket::Constants.should.const_defined?("PF_IPX", false)
     end
   end
 
   it "defines address families" do
     consts = ["AF_INET6", "AF_INET", "AF_UNIX", "AF_UNSPEC"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
   platform_is_not :aix do
     it "defines AF_IPX address" do
-      Socket::Constants.should have_constant("AF_IPX")
+      Socket::Constants.should.const_defined?("AF_IPX", false)
     end
   end
 
   it "defines send/receive options" do
     consts = ["MSG_DONTROUTE", "MSG_OOB", "MSG_PEEK"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
   it "defines socket level options" do
     consts = ["SOL_SOCKET"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
@@ -53,7 +53,7 @@ describe "Socket::Constants" do
     consts = ["SO_BROADCAST", "SO_DEBUG", "SO_DONTROUTE", "SO_ERROR", "SO_KEEPALIVE", "SO_LINGER",
               "SO_OOBINLINE", "SO_RCVBUF", "SO_REUSEADDR", "SO_SNDBUF", "SO_TYPE"]
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
@@ -64,15 +64,15 @@ describe "Socket::Constants" do
       consts += ["IP_DEFAULT_MULTICAST_LOOP", "IP_DEFAULT_MULTICAST_TTL"]
     end
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
-  platform_is_not :solaris, :windows, :aix do
+  platform_is_not :windows, :aix, :android do
     it "defines multicast options" do
       consts = ["IP_MAX_MEMBERSHIPS"]
       consts.each do |c|
-        Socket::Constants.should have_constant(c)
+        Socket::Constants.should.const_defined?(c, false)
       end
     end
   end
@@ -83,13 +83,13 @@ describe "Socket::Constants" do
       consts << "TCP_MAXSEG"
     end
     consts.each do |c|
-      Socket::Constants.should have_constant(c)
+      Socket::Constants.should.const_defined?(c, false)
     end
   end
 
   platform_is_not :windows do
     it 'defines SCM options' do
-      Socket::Constants.should have_constant('SCM_RIGHTS')
+      Socket::Constants.should.const_defined?('SCM_RIGHTS', false)
     end
 
     it 'defines error options' do
@@ -101,7 +101,7 @@ describe "Socket::Constants" do
       end
 
       consts.each do |c|
-        Socket::Constants.should have_constant(c)
+        Socket::Constants.should.const_defined?(c, false)
       end
     end
   end
diff --git a/spec/ruby/library/socket/fixtures/classes.rb b/spec/ruby/library/socket/fixtures/classes.rb
index 4a590502ca..786629d2ef 100644
--- a/spec/ruby/library/socket/fixtures/classes.rb
+++ b/spec/ruby/library/socket/fixtures/classes.rb
@@ -37,7 +37,9 @@ module SocketSpecs
     # Check for too long unix socket path (max 104 bytes on macOS)
     # Note that Linux accepts not null-terminated paths but the man page advises against it.
     if path.bytesize > 104
-      path = "/tmp/unix_server_spec.socket"
+      # rm_r in spec/mspec/lib/mspec/helpers/fs.rb fails against
+      # "/tmp/unix_server_spec.socket"
+      skip "too long unix socket path: #{path}"
     end
     rm_socket(path)
     path
@@ -111,7 +113,7 @@ module SocketSpecs
       begin
         data = socket.recv(1024)
 
-        return if data.empty?
+        return if data.nil? || data.empty?
         log "SpecTCPServer received: #{data.inspect}"
 
         return if data == "QUIT"
diff --git a/spec/ruby/library/socket/ipsocket/addr_spec.rb b/spec/ruby/library/socket/ipsocket/addr_spec.rb
index 199eb85ab7..eb16a8efdf 100644
--- a/spec/ruby/library/socket/ipsocket/addr_spec.rb
+++ b/spec/ruby/library/socket/ipsocket/addr_spec.rb
@@ -17,7 +17,7 @@ describe "Socket::IPSocket#addr" do
     BasicSocket.do_not_reverse_lookup = false
     addrinfo = @socket.addr
     addrinfo[0].should == "AF_INET"
-    addrinfo[1].should be_kind_of(Integer)
+    addrinfo[1].should.is_a?(Integer)
     addrinfo[2].should == SocketSpecs.hostname
     addrinfo[3].should == "127.0.0.1"
   end
@@ -27,7 +27,7 @@ describe "Socket::IPSocket#addr" do
     BasicSocket.do_not_reverse_lookup = true
     addrinfo = @socket.addr
     addrinfo[0].should == "AF_INET"
-    addrinfo[1].should be_kind_of(Integer)
+    addrinfo[1].should.is_a?(Integer)
     addrinfo[2].should == "127.0.0.1"
     addrinfo[3].should == "127.0.0.1"
   end
@@ -35,7 +35,7 @@ describe "Socket::IPSocket#addr" do
   it "returns an address in the array if passed false" do
     addrinfo = @socket.addr(false)
     addrinfo[0].should == "AF_INET"
-    addrinfo[1].should be_kind_of(Integer)
+    addrinfo[1].should.is_a?(Integer)
     addrinfo[2].should == "127.0.0.1"
     addrinfo[3].should == "127.0.0.1"
   end
@@ -81,7 +81,7 @@ describe 'Socket::IPSocket#addr' do
 
       describe 'using :cats as the argument' do
         it 'raises ArgumentError' do
-          -> { @server.addr(:cats) }.should raise_error(ArgumentError)
+          -> { @server.addr(:cats) }.should.raise(ArgumentError)
         end
       end
     end
diff --git a/spec/ruby/library/socket/ipsocket/getaddress_spec.rb b/spec/ruby/library/socket/ipsocket/getaddress_spec.rb
index 746d2ab86b..d302cd6a8a 100644
--- a/spec/ruby/library/socket/ipsocket/getaddress_spec.rb
+++ b/spec/ruby/library/socket/ipsocket/getaddress_spec.rb
@@ -2,7 +2,6 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "Socket::IPSocket#getaddress" do
-
   it "returns the IP address of hostname" do
     addr_local = IPSocket.getaddress(SocketSpecs.hostname)
     ["127.0.0.1", "::1"].include?(addr_local).should == true
@@ -14,12 +13,16 @@ describe "Socket::IPSocket#getaddress" do
     IPSocket.getaddress('::1').should == '::1'
   end
 
+  it 'returns IPv4 compatible IPv6 addresses' do
+    IPSocket.getaddress('::ffff:192.168.1.1').should == '::ffff:192.168.1.1'
+  end
+
   # There is no way to make this fail-proof on all machines, because
   # DNS servers like opendns return A records for ANY host, including
   # traditionally invalidly named ones.
   it "raises an error on unknown hostnames" do
     -> {
-      IPSocket.getaddress("rubyspecdoesntexist.fallingsnow.net")
-    }.should raise_error(SocketError)
+      IPSocket.getaddress("rubyspecdoesntexist.ruby-lang.org")
+    }.should.raise(SocketError)
   end
 end
diff --git a/spec/ruby/library/socket/ipsocket/inspect_spec.rb b/spec/ruby/library/socket/ipsocket/inspect_spec.rb
new file mode 100644
index 0000000000..85780a16f6
--- /dev/null
+++ b/spec/ruby/library/socket/ipsocket/inspect_spec.rb
@@ -0,0 +1,24 @@
+require_relative '../spec_helper'
+
+describe 'IPSocket#inspect' do
+  it "returns a String with the fd, family, address and port for TCPSocket" do
+    @server = TCPServer.new("127.0.0.1", 0)
+    @socket = TCPSocket.new("127.0.0.1", @server.addr[1])
+    port = @socket.addr[1]
+
+    @socket.inspect.should == "#<TCPSocket:fd #{@socket.fileno}, AF_INET, 127.0.0.1, #{port}>"
+  ensure
+    @socket&.close
+    @server&.close
+  end
+
+  it 'returns a String with the fd, family, address and port for UDPSocket' do
+    @socket = UDPSocket.new
+    @socket.bind('127.0.0.1', 0)
+    port = @socket.addr[1]
+
+    @socket.inspect.should == "#<UDPSocket:fd #{@socket.fileno}, AF_INET, 127.0.0.1, #{port}>"
+  ensure
+    @socket&.close
+  end
+end
diff --git a/spec/ruby/library/socket/ipsocket/peeraddr_spec.rb b/spec/ruby/library/socket/ipsocket/peeraddr_spec.rb
index 702650940b..b79222000a 100644
--- a/spec/ruby/library/socket/ipsocket/peeraddr_spec.rb
+++ b/spec/ruby/library/socket/ipsocket/peeraddr_spec.rb
@@ -18,7 +18,7 @@ describe "Socket::IPSocket#peeraddr" do
   it "raises error if socket is not connected" do
     -> {
       @server.peeraddr
-    }.should raise_error(Errno::ENOTCONN)
+    }.should.raise(Errno::ENOTCONN)
   end
 
   it "returns an array of information on the peer" do
@@ -92,7 +92,7 @@ describe 'Socket::IPSocket#peeraddr' do
 
       describe 'using :cats as the argument' do
         it 'raises ArgumentError' do
-          -> { @client.peeraddr(:cats) }.should raise_error(ArgumentError)
+          -> { @client.peeraddr(:cats) }.should.raise(ArgumentError)
         end
       end
     end
diff --git a/spec/ruby/library/socket/ipsocket/recvfrom_spec.rb b/spec/ruby/library/socket/ipsocket/recvfrom_spec.rb
index 3bcb7b8f02..7af0078be1 100644
--- a/spec/ruby/library/socket/ipsocket/recvfrom_spec.rb
+++ b/spec/ruby/library/socket/ipsocket/recvfrom_spec.rb
@@ -64,11 +64,71 @@ describe "Socket::IPSocket#recvfrom" do
 
     data.size.should == 2
     data.first.should == "hel"
-    # This does not apply to every platform, dependant on recvfrom(2)
+    # This does not apply to every platform, dependent on recvfrom(2)
     # data.last.should == nil
   end
 end
 
+describe "Socket::IPSocket#recvfrom" do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = TCPServer.new("127.0.0.1", 0)
+        port = @server.addr[1]
+        @client = TCPSocket.new("127.0.0.1", port)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      it "returns nil on a closed stream socket" do
+        t = Thread.new do
+          client = @server.accept
+          message = client.recvfrom(10)
+          message
+        ensure
+          client.close if client
+        end
+
+        Thread.pass while t.status and t.status != "sleep"
+        t.status.should_not == nil
+
+        @client.close
+
+        t.value.should == nil
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = UDPSocket.new(family)
+          @client = UDPSocket.new(family)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(ip_address, 0)
+          addr = @server.connect_address
+          @client.connect(addr.ip_address, addr.ip_port)
+
+          @client.send('', 0)
+          message = @server.recvfrom(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
+
 describe 'Socket::IPSocket#recvfrom' do
   SocketSpecs.each_ip_protocol do |family, ip_address, family_name|
     before do
diff --git a/spec/ruby/library/socket/option/bool_spec.rb b/spec/ruby/library/socket/option/bool_spec.rb
index 144a78043d..9992e842b3 100644
--- a/spec/ruby/library/socket/option/bool_spec.rb
+++ b/spec/ruby/library/socket/option/bool_spec.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe "Socket::Option.bool" do
   it "creates a new Socket::Option" do
     so = Socket::Option.bool(:INET, :SOCKET, :KEEPALIVE, true)
-    so.should be_an_instance_of(Socket::Option)
+    so.should.instance_of?(Socket::Option)
     so.family.should == Socket::AF_INET
     so.level.should == Socket::SOL_SOCKET
     so.optname.should == Socket::SO_KEEPALIVE
@@ -21,7 +21,7 @@ describe "Socket::Option#bool" do
   platform_is_not :windows do
     it 'raises TypeError when called on a non boolean option' do
       opt = Socket::Option.linger(1, 4)
-      -> { opt.bool }.should raise_error(TypeError)
+      -> { opt.bool }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/option/initialize_spec.rb b/spec/ruby/library/socket/option/initialize_spec.rb
index 8071ad7ef0..5af274f332 100644
--- a/spec/ruby/library/socket/option/initialize_spec.rb
+++ b/spec/ruby/library/socket/option/initialize_spec.rb
@@ -10,7 +10,7 @@ describe 'Socket::Option#initialize' do
       opt = Socket::Option
         .new(Socket::AF_INET, Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, @bool)
 
-      opt.should be_an_instance_of(Socket::Option)
+      opt.should.instance_of?(Socket::Option)
 
       opt.family.should  == Socket::AF_INET
       opt.level.should   == Socket::SOL_SOCKET
@@ -23,7 +23,7 @@ describe 'Socket::Option#initialize' do
     it 'returns a Socket::Option' do
       opt = Socket::Option.new(:INET, :SOCKET, :KEEPALIVE, @bool)
 
-      opt.should be_an_instance_of(Socket::Option)
+      opt.should.instance_of?(Socket::Option)
 
       opt.family.should  == Socket::AF_INET
       opt.level.should   == Socket::SOL_SOCKET
@@ -34,19 +34,19 @@ describe 'Socket::Option#initialize' do
     it 'raises when using an invalid address family' do
       -> {
         Socket::Option.new(:INET2, :SOCKET, :KEEPALIVE, @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
 
     it 'raises when using an invalid level' do
       -> {
         Socket::Option.new(:INET, :CATS, :KEEPALIVE, @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
 
     it 'raises when using an invalid option name' do
       -> {
         Socket::Option.new(:INET, :SOCKET, :CATS, @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
   end
 
@@ -54,7 +54,7 @@ describe 'Socket::Option#initialize' do
     it 'returns a Socket::Option' do
       opt = Socket::Option.new('INET', 'SOCKET', 'KEEPALIVE', @bool)
 
-      opt.should be_an_instance_of(Socket::Option)
+      opt.should.instance_of?(Socket::Option)
 
       opt.family.should  == Socket::AF_INET
       opt.level.should   == Socket::SOL_SOCKET
@@ -65,19 +65,19 @@ describe 'Socket::Option#initialize' do
     it 'raises when using an invalid address family' do
       -> {
         Socket::Option.new('INET2', 'SOCKET', 'KEEPALIVE', @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
 
     it 'raises when using an invalid level' do
       -> {
         Socket::Option.new('INET', 'CATS', 'KEEPALIVE', @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
 
     it 'raises when using an invalid option name' do
       -> {
         Socket::Option.new('INET', 'SOCKET', 'CATS', @bool)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/option/int_spec.rb b/spec/ruby/library/socket/option/int_spec.rb
index 8c69ef6cbd..0cd341f88a 100644
--- a/spec/ruby/library/socket/option/int_spec.rb
+++ b/spec/ruby/library/socket/option/int_spec.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe "Socket::Option.int" do
   it "creates a new Socket::Option" do
     so = Socket::Option.int(:INET, :SOCKET, :KEEPALIVE, 5)
-    so.should be_an_instance_of(Socket::Option)
+    so.should.instance_of?(Socket::Option)
     so.family.should == Socket::Constants::AF_INET
     so.level.should == Socket::Constants::SOL_SOCKET
     so.optname.should == Socket::Constants::SO_KEEPALIVE
@@ -14,7 +14,7 @@ describe "Socket::Option.int" do
   it 'returns a Socket::Option' do
     opt = Socket::Option.int(:INET, :IP, :TTL, 4)
 
-    opt.should be_an_instance_of(Socket::Option)
+    opt.should.instance_of?(Socket::Option)
 
     opt.family.should  == Socket::AF_INET
     opt.level.should   == Socket::IPPROTO_IP
@@ -37,7 +37,7 @@ describe "Socket::Option#int" do
   platform_is_not :windows do
     it 'raises TypeError when called on a non integer option' do
       opt = Socket::Option.linger(1, 4)
-      -> { opt.int }.should raise_error(TypeError)
+      -> { opt.int }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/option/linger_spec.rb b/spec/ruby/library/socket/option/linger_spec.rb
index ee987db85b..87c5e0982e 100644
--- a/spec/ruby/library/socket/option/linger_spec.rb
+++ b/spec/ruby/library/socket/option/linger_spec.rb
@@ -9,7 +9,7 @@ end
 describe "Socket::Option.linger" do
   it "creates a new Socket::Option for SO_LINGER" do
     so = Socket::Option.linger(1, 10)
-    so.should be_an_instance_of(Socket::Option)
+    so.should.instance_of?(Socket::Option)
 
     so.family.should == Socket::Constants::AF_UNSPEC
     so.level.should == Socket::Constants::SOL_SOCKET
@@ -31,46 +31,46 @@ describe "Socket::Option#linger" do
   it "returns linger option" do
     so = Socket::Option.linger(0, 5)
     ary = so.linger
-    ary[0].should be_false
+    ary[0].should == false
     ary[1].should == 5
 
     so = Socket::Option.linger(false, 4)
     ary = so.linger
-    ary[0].should be_false
+    ary[0].should == false
     ary[1].should == 4
 
     so = Socket::Option.linger(1, 10)
     ary = so.linger
-    ary[0].should be_true
+    ary[0].should == true
     ary[1].should == 10
 
     so = Socket::Option.linger(true, 9)
     ary = so.linger
-    ary[0].should be_true
+    ary[0].should == true
     ary[1].should == 9
   end
 
   it "raises TypeError if not a SO_LINGER" do
     so = Socket::Option.int(:AF_UNSPEC, :SOL_SOCKET, :KEEPALIVE, 1)
-    -> { so.linger }.should raise_error(TypeError)
+    -> { so.linger }.should.raise(TypeError)
   end
 
   it 'raises TypeError when called on a non SOL_SOCKET/SO_LINGER option' do
     opt = Socket::Option.int(:INET, :IP, :TTL, 4)
 
-    -> { opt.linger }.should raise_error(TypeError)
+    -> { opt.linger }.should.raise(TypeError)
   end
 
   platform_is_not :windows do
     it "raises TypeError if option has not good size" do
       so = Socket::Option.int(:AF_UNSPEC, :SOL_SOCKET, :LINGER, 1)
-      -> { so.linger }.should raise_error(TypeError)
+      -> { so.linger }.should.raise(TypeError)
     end
   end
 
   it 'raises TypeError when called on a non linger option' do
     opt = Socket::Option.new(:INET, :SOCKET, :LINGER, '')
 
-    -> { opt.linger }.should raise_error(TypeError)
+    -> { opt.linger }.should.raise(TypeError)
   end
 end
diff --git a/spec/ruby/library/socket/option/new_spec.rb b/spec/ruby/library/socket/option/new_spec.rb
index a9e6f09097..3721d63ee5 100644
--- a/spec/ruby/library/socket/option/new_spec.rb
+++ b/spec/ruby/library/socket/option/new_spec.rb
@@ -22,14 +22,14 @@ describe "Socket::Option.new" do
   end
 
   it "should raise error on unknown family" do
-    -> { Socket::Option.new(:INET4, :SOCKET, :KEEPALIVE, [0].pack('i')) }.should raise_error(SocketError)
+    -> { Socket::Option.new(:INET4, :SOCKET, :KEEPALIVE, [0].pack('i')) }.should.raise(SocketError)
   end
 
   it "should raise error on unknown level" do
-    -> { Socket::Option.new(:INET, :ROCKET, :KEEPALIVE, [0].pack('i')) }.should raise_error(SocketError)
+    -> { Socket::Option.new(:INET, :ROCKET, :KEEPALIVE, [0].pack('i')) }.should.raise(SocketError)
   end
 
   it "should raise error on unknown option name" do
-    -> { Socket::Option.new(:INET, :SOCKET, :ALIVE, [0].pack('i')) }.should raise_error(SocketError)
+    -> { Socket::Option.new(:INET, :SOCKET, :ALIVE, [0].pack('i')) }.should.raise(SocketError)
   end
 end
diff --git a/spec/ruby/library/socket/shared/address.rb b/spec/ruby/library/socket/shared/address.rb
new file mode 100644
index 0000000000..c64602df2f
--- /dev/null
+++ b/spec/ruby/library/socket/shared/address.rb
@@ -0,0 +1,259 @@
+require_relative '../fixtures/classes'
+
+describe :socket_local_remote_address, shared: true do
+  describe 'using TCPSocket' do
+    before :each do
+      @s = TCPServer.new('127.0.0.1', 0)
+      @a = TCPSocket.new('127.0.0.1', @s.addr[1])
+      @b = @s.accept
+      @addr = @object.call(@a)
+    end
+
+    after :each do
+      [@b, @a, @s].each(&:close)
+    end
+
+    it 'uses AF_INET as the address family' do
+      @addr.afamily.should == Socket::AF_INET
+    end
+
+    it 'uses PF_INET as the protocol family' do
+      @addr.pfamily.should == Socket::PF_INET
+    end
+
+    it 'uses SOCK_STREAM as the socket type' do
+      @addr.socktype.should == Socket::SOCK_STREAM
+    end
+
+    it 'uses the correct IP address' do
+      @addr.ip_address.should == '127.0.0.1'
+    end
+
+    it 'uses the correct port' do
+      if @method == :local_address
+        @addr.ip_port.should != @s.addr[1]
+      else
+        @addr.ip_port.should == @s.addr[1]
+      end
+    end
+
+    it 'equals address of peer socket' do
+      if @method == :local_address
+        @addr.to_s.should == @b.remote_address.to_s
+      else
+        @addr.to_s.should == @b.local_address.to_s
+      end
+    end
+
+    it 'returns an Addrinfo' do
+      @addr.should.instance_of?(Addrinfo)
+    end
+
+    it 'uses 0 as the protocol' do
+      @addr.protocol.should == 0
+    end
+
+    it 'can be used to connect to the server' do
+      skip if @method == :local_address
+      b = @addr.connect
+      begin
+        b.remote_address.to_s.should == @addr.to_s
+      ensure
+        b.close
+      end
+    end
+  end
+
+  guard -> { SocketSpecs.ipv6_available? } do
+    describe 'using IPv6' do
+      before :each do
+        @s = TCPServer.new('::1', 0)
+        @a = TCPSocket.new('::1', @s.addr[1])
+        @b = @s.accept
+        @addr = @object.call(@a)
+      end
+
+      after :each do
+        [@b, @a, @s].each(&:close)
+      end
+
+      it 'uses AF_INET6 as the address family' do
+        @addr.afamily.should == Socket::AF_INET6
+      end
+
+      it 'uses PF_INET6 as the protocol family' do
+        @addr.pfamily.should == Socket::PF_INET6
+      end
+
+      it 'uses SOCK_STREAM as the socket type' do
+        @addr.socktype.should == Socket::SOCK_STREAM
+      end
+
+      it 'uses the correct IP address' do
+        @addr.ip_address.should == '::1'
+      end
+
+      it 'uses the correct port' do
+        if @method == :local_address
+          @addr.ip_port.should != @s.addr[1]
+        else
+          @addr.ip_port.should == @s.addr[1]
+        end
+      end
+
+      it 'equals address of peer socket' do
+        if @method == :local_address
+          @addr.to_s.should == @b.remote_address.to_s
+        else
+          @addr.to_s.should == @b.local_address.to_s
+        end
+      end
+
+      it 'returns an Addrinfo' do
+        @addr.should.instance_of?(Addrinfo)
+      end
+
+      it 'uses 0 as the protocol' do
+        @addr.protocol.should == 0
+      end
+
+      it 'can be used to connect to the server' do
+        skip if @method == :local_address
+        b = @addr.connect
+        begin
+          b.remote_address.to_s.should == @addr.to_s
+        ensure
+          b.close
+        end
+      end
+    end
+  end
+
+  describe 'using UNIXSocket' do
+    before :each do
+      @path = SocketSpecs.socket_path
+      @s = UNIXServer.new(@path)
+      @a = UNIXSocket.new(@path)
+      @b = @s.accept
+      @addr = @object.call(@a)
+    end
+
+    after :each do
+      [@b, @a, @s].each(&:close)
+      rm_r(@path)
+    end
+
+    it 'uses AF_UNIX as the address family' do
+      @addr.afamily.should == Socket::AF_UNIX
+    end
+
+    it 'uses PF_UNIX as the protocol family' do
+      @addr.pfamily.should == Socket::PF_UNIX
+    end
+
+    it 'uses SOCK_STREAM as the socket type' do
+      @addr.socktype.should == Socket::SOCK_STREAM
+    end
+
+    it 'uses the correct socket path' do
+      if @method == :local_address
+        @addr.unix_path.should == ""
+      else
+        @addr.unix_path.should == @path
+      end
+    end
+
+    platform_is_not :windows do
+      it 'equals address of peer socket' do
+        if @method == :local_address
+          @addr.to_s.should == @b.remote_address.to_s
+        else
+          @addr.to_s.should == @b.local_address.to_s
+        end
+      end
+    end
+
+    guard -> { platform_is :windows and ruby_bug "#21702", ""..."4.2" } do
+      it 'equals address of peer socket' do
+        if @method == :local_address
+          @addr.to_s.should == @b.remote_address.to_s
+        else
+          @addr.to_s.should == @b.local_address.to_s
+        end
+      end
+    end
+
+    it 'returns an Addrinfo' do
+      @addr.should.instance_of?(Addrinfo)
+    end
+
+    it 'uses 0 as the protocol' do
+      @addr.protocol.should == 0
+    end
+
+    it 'can be used to connect to the server' do
+      skip if @method == :local_address
+      b = @addr.connect
+      begin
+        b.remote_address.to_s.should == @addr.to_s
+      ensure
+        b.close
+      end
+    end
+  end
+
+  describe 'using UDPSocket' do
+    before :each do
+      @s = UDPSocket.new
+      @s.bind("127.0.0.1", 0)
+      @a = UDPSocket.new
+      @a.connect("127.0.0.1", @s.addr[1])
+      @addr = @object.call(@a)
+    end
+
+    after :each do
+      [@a, @s].each(&:close)
+    end
+
+    it 'uses the correct address family' do
+      @addr.afamily.should == Socket::AF_INET
+    end
+
+    it 'uses the correct protocol family' do
+      @addr.pfamily.should == Socket::PF_INET
+    end
+
+    it 'uses SOCK_DGRAM as the socket type' do
+      @addr.socktype.should == Socket::SOCK_DGRAM
+    end
+
+    it 'uses the correct IP address' do
+      @addr.ip_address.should == '127.0.0.1'
+    end
+
+    it 'uses the correct port' do
+      if @method == :local_address
+        @addr.ip_port.should != @s.addr[1]
+      else
+        @addr.ip_port.should == @s.addr[1]
+      end
+    end
+
+    it 'returns an Addrinfo' do
+      @addr.should.instance_of?(Addrinfo)
+    end
+
+    it 'uses 0 as the protocol' do
+      @addr.protocol.should == 0
+    end
+
+    it 'can be used to connect to the peer' do
+      b = @addr.connect
+      begin
+        b.remote_address.to_s.should == @addr.to_s
+      ensure
+        b.close
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/shared/pack_sockaddr.rb b/spec/ruby/library/socket/shared/pack_sockaddr.rb
index 2df09027c9..db6f39612d 100644
--- a/spec/ruby/library/socket/shared/pack_sockaddr.rb
+++ b/spec/ruby/library/socket/shared/pack_sockaddr.rb
@@ -17,65 +17,58 @@ describe :socket_pack_sockaddr_in, shared: true do
 
     sockaddr_in = Socket.public_send(@method, nil, '127.0.0.1')
     Socket.unpack_sockaddr_in(sockaddr_in).should == [0, '127.0.0.1']
+
+    sockaddr_in = Socket.public_send(@method, 80, Socket::INADDR_ANY)
+    Socket.unpack_sockaddr_in(sockaddr_in).should == [80, '0.0.0.0']
+  end
+
+  it 'resolves the service name to a port' do
+    sockaddr_in = Socket.public_send(@method, 'http', '127.0.0.1')
+    Socket.unpack_sockaddr_in(sockaddr_in).should == [80, '127.0.0.1']
   end
 
   describe 'using an IPv4 address' do
     it 'returns a String of 16 bytes' do
       str = Socket.public_send(@method, 80, '127.0.0.1')
 
-      str.should be_an_instance_of(String)
+      str.should.instance_of?(String)
       str.bytesize.should == 16
     end
   end
 
-  platform_is_not :solaris do
-    describe 'using an IPv6 address' do
-      it 'returns a String of 28 bytes' do
-        str = Socket.public_send(@method, 80, '::1')
-
-        str.should be_an_instance_of(String)
-        str.bytesize.should == 28
-      end
-    end
-  end
-
-  platform_is :solaris do
-    describe 'using an IPv6 address' do
-      it 'returns a String of 32 bytes' do
-        str = Socket.public_send(@method, 80, '::1')
+  describe 'using an IPv6 address' do
+    it 'returns a String of 28 bytes' do
+      str = Socket.public_send(@method, 80, '::1')
 
-        str.should be_an_instance_of(String)
-        str.bytesize.should == 32
-      end
+      str.should.instance_of?(String)
+      str.bytesize.should == 28
     end
   end
 end
 
 describe :socket_pack_sockaddr_un, shared: true do
-  with_feature :unix_socket do
-    it 'should be idempotent' do
-      bytes = Socket.public_send(@method, '/tmp/foo').bytes
-      bytes[2..9].should == [47, 116, 109, 112, 47, 102, 111, 111]
-      bytes[10..-1].all?(&:zero?).should == true
-    end
+  it 'should be idempotent' do
+    bytes = Socket.public_send(@method, '/tmp/foo').bytes
+    bytes[2..9].should == [47, 116, 109, 112, 47, 102, 111, 111]
+    bytes[10..-1].all?(&:zero?).should == true
+  end
 
-    it "packs and unpacks" do
-      sockaddr_un = Socket.public_send(@method, '/tmp/s')
-      Socket.unpack_sockaddr_un(sockaddr_un).should == '/tmp/s'
-    end
+  it "packs and unpacks" do
+    sockaddr_un = Socket.public_send(@method, '/tmp/s')
+    Socket.unpack_sockaddr_un(sockaddr_un).should == '/tmp/s'
+  end
 
-    it "handles correctly paths with multibyte chars" do
-      sockaddr_un = Socket.public_send(@method, '/home/вася/sock')
-      path = Socket.unpack_sockaddr_un(sockaddr_un).encode('UTF-8', 'UTF-8')
-      path.should == '/home/вася/sock'
-    end
+  it "handles correctly paths with multibyte chars" do
+    sockaddr_un = Socket.public_send(@method, '/home/вася/sock')
+    path = Socket.unpack_sockaddr_un(sockaddr_un).encode('UTF-8', 'UTF-8')
+    path.should == '/home/вася/sock'
   end
 
   platform_is :linux do
     it 'returns a String of 110 bytes' do
       str = Socket.public_send(@method, '/tmp/test.sock')
 
-      str.should be_an_instance_of(String)
+      str.should.instance_of?(String)
       str.bytesize.should == 110
     end
   end
@@ -84,16 +77,16 @@ describe :socket_pack_sockaddr_un, shared: true do
     it 'returns a String of 106 bytes' do
       str = Socket.public_send(@method, '/tmp/test.sock')
 
-      str.should be_an_instance_of(String)
+      str.should.instance_of?(String)
       str.bytesize.should == 106
     end
   end
 
-  platform_is_not :windows, :aix do
+  platform_is_not :aix do
     it "raises ArgumentError for paths that are too long" do
       # AIX doesn't raise error
       long_path = 'a' * 110
-      -> { Socket.public_send(@method, long_path) }.should raise_error(ArgumentError)
+      -> { Socket.public_send(@method, long_path) }.should.raise(ArgumentError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/shared/partially_closable_sockets.rb b/spec/ruby/library/socket/shared/partially_closable_sockets.rb
index 1bdff08bf6..b1c2ebabe1 100644
--- a/spec/ruby/library/socket/shared/partially_closable_sockets.rb
+++ b/spec/ruby/library/socket/shared/partially_closable_sockets.rb
@@ -1,4 +1,4 @@
-describe "partially closable sockets", shared: true do
+describe :partially_closable_sockets, shared: true do
   it "if the write end is closed then the other side can read past EOF without blocking" do
     @s1.write("foo")
     @s1.close_write
diff --git a/spec/ruby/library/socket/shared/socketpair.rb b/spec/ruby/library/socket/shared/socketpair.rb
index 25146cfff6..7fcd4d6b46 100644
--- a/spec/ruby/library/socket/shared/socketpair.rb
+++ b/spec/ruby/library/socket/shared/socketpair.rb
@@ -12,8 +12,8 @@ describe :socket_socketpair, shared: true do
       begin
         s1, s2 = Socket.public_send(@method, :UNIX, :STREAM)
 
-        s1.should be_an_instance_of(Socket)
-        s2.should be_an_instance_of(Socket)
+        s1.should.instance_of?(Socket)
+        s2.should.instance_of?(Socket)
       ensure
         s1.close
         s2.close
@@ -24,8 +24,8 @@ describe :socket_socketpair, shared: true do
       it 'returns two Socket objects' do
         s1, s2 = Socket.public_send(@method, Socket::AF_UNIX, Socket::SOCK_STREAM)
 
-        s1.should be_an_instance_of(Socket)
-        s2.should be_an_instance_of(Socket)
+        s1.should.instance_of?(Socket)
+        s2.should.instance_of?(Socket)
         s1.close
         s2.close
       end
@@ -35,18 +35,18 @@ describe :socket_socketpair, shared: true do
       it 'returns two Socket objects' do
         s1, s2 = Socket.public_send(@method, :UNIX, :STREAM)
 
-        s1.should be_an_instance_of(Socket)
-        s2.should be_an_instance_of(Socket)
+        s1.should.instance_of?(Socket)
+        s2.should.instance_of?(Socket)
         s1.close
         s2.close
       end
 
       it 'raises SocketError for an unknown address family' do
-        -> { Socket.public_send(@method, :CATS, :STREAM) }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, :CATS, :STREAM) }.should.raise(SocketError)
       end
 
       it 'raises SocketError for an unknown socket type' do
-        -> { Socket.public_send(@method, :UNIX, :CATS) }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, :UNIX, :CATS) }.should.raise(SocketError)
       end
     end
 
@@ -54,18 +54,18 @@ describe :socket_socketpair, shared: true do
       it 'returns two Socket objects' do
         s1, s2 = Socket.public_send(@method, 'UNIX', 'STREAM')
 
-        s1.should be_an_instance_of(Socket)
-        s2.should be_an_instance_of(Socket)
+        s1.should.instance_of?(Socket)
+        s2.should.instance_of?(Socket)
         s1.close
         s2.close
       end
 
       it 'raises SocketError for an unknown address family' do
-        -> { Socket.public_send(@method, 'CATS', 'STREAM') }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, 'CATS', 'STREAM') }.should.raise(SocketError)
       end
 
       it 'raises SocketError for an unknown socket type' do
-        -> { Socket.public_send(@method, 'UNIX', 'CATS') }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, 'UNIX', 'CATS') }.should.raise(SocketError)
       end
     end
 
@@ -79,8 +79,8 @@ describe :socket_socketpair, shared: true do
 
         s1, s2 = Socket.public_send(@method, family, type)
 
-        s1.should be_an_instance_of(Socket)
-        s2.should be_an_instance_of(Socket)
+        s1.should.instance_of?(Socket)
+        s2.should.instance_of?(Socket)
         s1.close
         s2.close
       end
@@ -92,7 +92,7 @@ describe :socket_socketpair, shared: true do
         family.stub!(:to_str).and_return(Socket::AF_UNIX)
         type.stub!(:to_str).and_return(Socket::SOCK_STREAM)
 
-        -> { Socket.public_send(@method, family, type) }.should raise_error(TypeError)
+        -> { Socket.public_send(@method, family, type) }.should.raise(TypeError)
       end
 
       it 'raises SocketError for an unknown address family' do
@@ -102,7 +102,7 @@ describe :socket_socketpair, shared: true do
         family.stub!(:to_str).and_return('CATS')
         type.stub!(:to_str).and_return('STREAM')
 
-        -> { Socket.public_send(@method, family, type) }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, family, type) }.should.raise(SocketError)
       end
 
       it 'raises SocketError for an unknown socket type' do
@@ -112,14 +112,14 @@ describe :socket_socketpair, shared: true do
         family.stub!(:to_str).and_return('UNIX')
         type.stub!(:to_str).and_return('CATS')
 
-        -> { Socket.public_send(@method, family, type) }.should raise_error(SocketError)
+        -> { Socket.public_send(@method, family, type) }.should.raise(SocketError)
       end
     end
 
     it 'accepts a custom protocol as an Integer as the 3rd argument' do
       s1, s2 = Socket.public_send(@method, :UNIX, :STREAM, Socket::IPPROTO_IP)
-      s1.should be_an_instance_of(Socket)
-      s2.should be_an_instance_of(Socket)
+      s1.should.instance_of?(Socket)
+      s2.should.instance_of?(Socket)
       s1.close
       s2.close
     end
diff --git a/spec/ruby/library/socket/socket/accept_loop_spec.rb b/spec/ruby/library/socket/socket/accept_loop_spec.rb
index 78e8c3fa4a..6c65b192ed 100644
--- a/spec/ruby/library/socket/socket/accept_loop_spec.rb
+++ b/spec/ruby/library/socket/socket/accept_loop_spec.rb
@@ -41,8 +41,8 @@ describe 'Socket.accept_loop' do
         end
 
         begin
-          conn.should be_an_instance_of(Socket)
-          addr.should be_an_instance_of(Addrinfo)
+          conn.should.instance_of?(Socket)
+          addr.should.instance_of?(Addrinfo)
         ensure
           conn.close
         end
@@ -73,8 +73,8 @@ describe 'Socket.accept_loop' do
         end
 
         begin
-          conn.should be_an_instance_of(Socket)
-          addr.should be_an_instance_of(Addrinfo)
+          conn.should.instance_of?(Socket)
+          addr.should.instance_of?(Addrinfo)
         ensure
           conn.close
         end
diff --git a/spec/ruby/library/socket/socket/accept_nonblock_spec.rb b/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
index 3221f0b128..09cdbaa7b4 100644
--- a/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
+++ b/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
@@ -17,12 +17,12 @@ describe "Socket#accept_nonblock" do
   it "raises IO::WaitReadable if the connection is not accepted yet" do
     -> {
       @socket.accept_nonblock
-    }.should raise_error(IO::WaitReadable) { |e|
+    }.should.raise(IO::WaitReadable) { |e|
       platform_is_not :windows do
-        e.should be_kind_of(Errno::EAGAIN)
+        e.should.is_a?(Errno::EAGAIN)
       end
       platform_is :windows do
-        e.should be_kind_of(Errno::EWOULDBLOCK)
+        e.should.is_a?(Errno::EWOULDBLOCK)
       end
     }
   end
@@ -45,7 +45,8 @@ describe 'Socket#accept_nonblock' do
 
     describe 'using an unbound socket' do
       it 'raises Errno::EINVAL' do
-        -> { @server.accept_nonblock }.should raise_error(Errno::EINVAL)
+        -> { @server.accept_nonblock }.should.raise(Errno::EINVAL)
+        -> { @server.accept_nonblock(exception: false) }.should.raise(Errno::EINVAL)
       end
     end
 
@@ -55,7 +56,8 @@ describe 'Socket#accept_nonblock' do
       end
 
       it 'raises Errno::EINVAL' do
-        -> { @server.accept_nonblock }.should raise_error(Errno::EINVAL)
+        -> { @server.accept_nonblock }.should.raise(Errno::EINVAL)
+        -> { @server.accept_nonblock(exception: false) }.should.raise(Errno::EINVAL)
       end
     end
 
@@ -63,7 +65,8 @@ describe 'Socket#accept_nonblock' do
       it 'raises IOError' do
         @server.close
 
-        -> { @server.accept_nonblock }.should raise_error(IOError)
+        -> { @server.accept_nonblock }.should.raise(IOError)
+        -> { @server.accept_nonblock(exception: false) }.should.raise(IOError)
       end
     end
 
@@ -75,7 +78,7 @@ describe 'Socket#accept_nonblock' do
 
       describe 'without a connected client' do
         it 'raises IO::WaitReadable' do
-          -> { @server.accept_nonblock }.should raise_error(IO::WaitReadable)
+          -> { @server.accept_nonblock }.should.raise(IO::WaitReadable)
         end
       end
 
@@ -97,8 +100,8 @@ describe 'Socket#accept_nonblock' do
             IO.select([@server])
             @socket, addrinfo = @server.accept_nonblock
 
-            @socket.should be_an_instance_of(Socket)
-            addrinfo.should be_an_instance_of(Addrinfo)
+            @socket.should.instance_of?(Socket)
+            addrinfo.should.instance_of?(Addrinfo)
           end
 
           describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/socket/accept_spec.rb b/spec/ruby/library/socket/socket/accept_spec.rb
index 417f996c55..fca727ab08 100644
--- a/spec/ruby/library/socket/socket/accept_spec.rb
+++ b/spec/ruby/library/socket/socket/accept_spec.rb
@@ -15,7 +15,7 @@ describe 'Socket#accept' do
     platform_is :linux do # hangs on other platforms
       describe 'using an unbound socket'  do
         it 'raises Errno::EINVAL' do
-          -> { @server.accept }.should raise_error(Errno::EINVAL)
+          -> { @server.accept }.should.raise(Errno::EINVAL)
         end
       end
 
@@ -25,7 +25,7 @@ describe 'Socket#accept' do
         end
 
         it 'raises Errno::EINVAL' do
-          -> { @server.accept }.should raise_error(Errno::EINVAL)
+          -> { @server.accept }.should.raise(Errno::EINVAL)
         end
       end
     end
@@ -34,7 +34,7 @@ describe 'Socket#accept' do
       it 'raises IOError' do
         @server.close
 
-        -> { @server.accept }.should raise_error(IOError)
+        -> { @server.accept }.should.raise(IOError)
       end
     end
 
@@ -58,7 +58,7 @@ describe 'Socket#accept' do
 
           value = thread.value
           begin
-            value.should be_an_instance_of(Array)
+            value.should.instance_of?(Array)
           ensure
             client.close
             value[0].close
@@ -82,8 +82,8 @@ describe 'Socket#accept' do
         it 'returns an Array containing a Socket and an Addrinfo' do
           @socket, addrinfo = @server.accept
 
-          @socket.should be_an_instance_of(Socket)
-          addrinfo.should be_an_instance_of(Addrinfo)
+          @socket.should.instance_of?(Socket)
+          addrinfo.should.instance_of?(Addrinfo)
         end
 
         describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/socket/bind_spec.rb b/spec/ruby/library/socket/socket/bind_spec.rb
index 0349df84a6..164df92205 100644
--- a/spec/ruby/library/socket/socket/bind_spec.rb
+++ b/spec/ruby/library/socket/socket/bind_spec.rb
@@ -8,12 +8,12 @@ describe "Socket#bind on SOCK_DGRAM socket" do
   end
 
   after :each do
-    @sock.closed?.should be_false
+    @sock.closed?.should == false
     @sock.close
   end
 
   it "binds to a port" do
-    -> { @sock.bind(@sockaddr) }.should_not raise_error
+    -> { @sock.bind(@sockaddr) }.should_not.raise
   end
 
   it "returns 0 if successful" do
@@ -23,19 +23,20 @@ describe "Socket#bind on SOCK_DGRAM socket" do
   it "raises Errno::EINVAL when already bound" do
     @sock.bind(@sockaddr)
 
-    -> { @sock.bind(@sockaddr) }.should raise_error(Errno::EINVAL)
+    -> { @sock.bind(@sockaddr) }.should.raise(Errno::EINVAL)
   end
 
   it "raises Errno::EADDRNOTAVAIL when the specified sockaddr is not available from the local machine" do
     sockaddr1 = Socket.pack_sockaddr_in(0, "4.3.2.1")
-    -> { @sock.bind(sockaddr1) }.should raise_error(Errno::EADDRNOTAVAIL)
+    -> { @sock.bind(sockaddr1) }.should.raise(Errno::EADDRNOTAVAIL)
   end
 
   platform_is_not :windows, :cygwin do
     as_user do
+      break if File.read('/proc/sys/net/ipv4/ip_unprivileged_port_start').to_i <= 1 rescue nil
       it "raises Errno::EACCES when the current user does not have permission to bind" do
         sockaddr1 = Socket.pack_sockaddr_in(1, "127.0.0.1")
-        -> { @sock.bind(sockaddr1) }.should raise_error(Errno::EACCES)
+        -> { @sock.bind(sockaddr1) }.should.raise(Errno::EACCES)
       end
     end
   end
@@ -49,12 +50,12 @@ describe "Socket#bind on SOCK_STREAM socket" do
   end
 
   after :each do
-    @sock.closed?.should be_false
+    @sock.closed?.should == false
     @sock.close
   end
 
   it "binds to a port" do
-    -> { @sock.bind(@sockaddr) }.should_not raise_error
+    -> { @sock.bind(@sockaddr) }.should_not.raise
   end
 
   it "returns 0 if successful" do
@@ -64,19 +65,20 @@ describe "Socket#bind on SOCK_STREAM socket" do
   it "raises Errno::EINVAL when already bound" do
     @sock.bind(@sockaddr)
 
-    -> { @sock.bind(@sockaddr) }.should raise_error(Errno::EINVAL)
+    -> { @sock.bind(@sockaddr) }.should.raise(Errno::EINVAL)
   end
 
   it "raises Errno::EADDRNOTAVAIL when the specified sockaddr is not available from the local machine" do
     sockaddr1 = Socket.pack_sockaddr_in(0, "4.3.2.1")
-    -> { @sock.bind(sockaddr1) }.should raise_error(Errno::EADDRNOTAVAIL)
+    -> { @sock.bind(sockaddr1) }.should.raise(Errno::EADDRNOTAVAIL)
   end
 
   platform_is_not :windows, :cygwin do
     as_user do
+      break if File.read('/proc/sys/net/ipv4/ip_unprivileged_port_start').to_i <= 1 rescue nil
       it "raises Errno::EACCES when the current user does not have permission to bind" do
         sockaddr1 = Socket.pack_sockaddr_in(1, "127.0.0.1")
-        -> { @sock.bind(sockaddr1) }.should raise_error(Errno::EACCES)
+        -> { @sock.bind(sockaddr1) }.should.raise(Errno::EACCES)
       end
     end
   end
@@ -101,24 +103,26 @@ describe 'Socket#bind' do
       it 'raises Errno::EINVAL when binding to an already bound port' do
         @socket.bind(@sockaddr)
 
-        -> { @socket.bind(@sockaddr) }.should raise_error(Errno::EINVAL)
+        -> { @socket.bind(@sockaddr) }.should.raise(Errno::EINVAL)
       end
 
       it 'raises Errno::EADDRNOTAVAIL when the specified sockaddr is not available' do
         ip = family == Socket::AF_INET ? '4.3.2.1' : '::2'
         sockaddr1 = Socket.sockaddr_in(0, ip)
 
-        -> { @socket.bind(sockaddr1) }.should raise_error(Errno::EADDRNOTAVAIL)
+        -> { @socket.bind(sockaddr1) }.should.raise(Errno::EADDRNOTAVAIL)
       end
 
       platform_is_not :windows do
         as_user do
+          break if File.read('/proc/sys/net/ipv4/ip_unprivileged_port_start').to_i <= 1 rescue nil
+
           it 'raises Errno::EACCES when the user is not allowed to bind to the port' do
             sockaddr1 = Socket.pack_sockaddr_in(1, ip_address)
 
-            -> { @socket.bind(sockaddr1) }.should raise_error(Errno::EACCES)
+            -> { @socket.bind(sockaddr1) }.should.raise(Errno::EACCES)
           end
-       end
+        end
       end
     end
 
@@ -134,7 +138,7 @@ describe 'Socket#bind' do
 
       it 'binds to an Addrinfo' do
         @socket.bind(@addr).should == 0
-        @socket.local_address.should be_an_instance_of(Addrinfo)
+        @socket.local_address.should.instance_of?(Addrinfo)
       end
 
       it 'uses a new Addrinfo for the local address' do
diff --git a/spec/ruby/library/socket/socket/connect_nonblock_spec.rb b/spec/ruby/library/socket/socket/connect_nonblock_spec.rb
index 3cf667fc4a..dac24e3e5b 100644
--- a/spec/ruby/library/socket/socket/connect_nonblock_spec.rb
+++ b/spec/ruby/library/socket/socket/connect_nonblock_spec.rb
@@ -16,52 +16,50 @@ describe "Socket#connect_nonblock" do
     @thread.join if @thread
   end
 
-  platform_is_not :solaris do
-    it "connects the socket to the remote side" do
-      port = nil
-      accept = false
-      @thread = Thread.new do
-        server = TCPServer.new(@hostname, 0)
-        port = server.addr[1]
-        Thread.pass until accept
-        conn = server.accept
-        conn << "hello!"
-        conn.close
-        server.close
-      end
-
-      Thread.pass until port
+  it "connects the socket to the remote side" do
+    port = nil
+    accept = false
+    @thread = Thread.new do
+      server = TCPServer.new(@hostname, 0)
+      port = server.addr[1]
+      Thread.pass until accept
+      conn = server.accept
+      conn << "hello!"
+      conn.close
+      server.close
+    end
 
-      addr = Socket.sockaddr_in(port, @hostname)
-      begin
-        @socket.connect_nonblock(addr)
-      rescue Errno::EINPROGRESS
-      end
+    Thread.pass until port
 
-      accept = true
-      IO.select nil, [@socket]
+    addr = Socket.sockaddr_in(port, @hostname)
+    begin
+      @socket.connect_nonblock(addr)
+    rescue Errno::EINPROGRESS
+    end
 
-      begin
-        @socket.connect_nonblock(addr)
-      rescue Errno::EISCONN
-        # Not all OS's use this errno, so we trap and ignore it
-      end
+    accept = true
+    IO.select nil, [@socket]
 
-      @socket.read(6).should == "hello!"
+    begin
+      @socket.connect_nonblock(addr)
+    rescue Errno::EISCONN
+      # Not all OS's use this errno, so we trap and ignore it
     end
+
+    @socket.read(6).should == "hello!"
   end
 
-  platform_is_not :freebsd, :solaris, :aix do
+  platform_is_not :freebsd, :aix do
     it "raises Errno::EINPROGRESS when the connect would block" do
       -> do
         @socket.connect_nonblock(@addr)
-      end.should raise_error(Errno::EINPROGRESS)
+      end.should.raise(Errno::EINPROGRESS)
     end
 
     it "raises Errno::EINPROGRESS with IO::WaitWritable mixed in when the connect would block" do
       -> do
         @socket.connect_nonblock(@addr)
-      end.should raise_error(IO::WaitWritable)
+      end.should.raise(IO::WaitWritable)
     end
 
     it "returns :wait_writable in exceptionless mode when the connect would block" do
@@ -95,7 +93,7 @@ describe 'Socket#connect_nonblock' do
       end
 
       it 'raises TypeError when passed an Integer' do
-        -> { @client.connect_nonblock(666) }.should raise_error(TypeError)
+        -> { @client.connect_nonblock(666) }.should.raise(TypeError)
       end
     end
 
@@ -124,7 +122,7 @@ describe 'Socket#connect_nonblock' do
             # as it's too implementation-dependent and checking for connect()
             # errors is futile anyways because of TOCTOU
             @client.connect_nonblock(@server.connect_address)
-          }.should raise_error(Errno::EISCONN)
+          }.should.raise(Errno::EISCONN)
         end
 
         it 'returns 0 when already connected in exceptionless mode' do
@@ -135,13 +133,13 @@ describe 'Socket#connect_nonblock' do
         end
       end
 
-      platform_is_not :freebsd, :solaris do
+      platform_is_not :freebsd do
         it 'raises IO:EINPROGRESSWaitWritable when the connection would block' do
           @server.bind(@sockaddr)
 
           -> {
             @client.connect_nonblock(@server.connect_address)
-          }.should raise_error(IO::EINPROGRESSWaitWritable)
+          }.should.raise(IO::EINPROGRESSWaitWritable)
         end
       end
     end
diff --git a/spec/ruby/library/socket/socket/connect_spec.rb b/spec/ruby/library/socket/socket/connect_spec.rb
index 8653fba552..c928b66c53 100644
--- a/spec/ruby/library/socket/socket/connect_spec.rb
+++ b/spec/ruby/library/socket/socket/connect_spec.rb
@@ -40,7 +40,7 @@ describe 'Socket#connect' do
         # as it's too implementation-dependent and checking for connect()
         # errors is futile anyways because of TOCTOU
         @client.connect(@server.getsockname)
-      }.should raise_error(Errno::EISCONN)
+      }.should.raise(Errno::EISCONN)
     end
 
     platform_is_not :darwin do
@@ -53,4 +53,26 @@ describe 'Socket#connect' do
       end
     end
   end
+
+  ruby_version_is "3.4" do
+    it "fails with timeout" do
+      # TEST-NET-1 IP address are reserved for documentation and example purposes.
+      address = Socket.pack_sockaddr_in(1, "192.0.2.1")
+
+      client = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM)
+      client.timeout = 0
+
+      -> {
+        begin
+          client.connect(address)
+        rescue Errno::ECONNREFUSED
+          skip "Outgoing packets may be filtered"
+        rescue Errno::ENETUNREACH
+          skip "Off line"
+        end
+      }.should.raise(IO::TimeoutError)
+    ensure
+      client.close
+    end
+  end
 end
diff --git a/spec/ruby/library/socket/socket/getaddrinfo_spec.rb b/spec/ruby/library/socket/socket/getaddrinfo_spec.rb
index e0eff3cef4..7e5bdc9b25 100644
--- a/spec/ruby/library/socket/socket/getaddrinfo_spec.rb
+++ b/spec/ruby/library/socket/socket/getaddrinfo_spec.rb
@@ -11,7 +11,7 @@ describe "Socket.getaddrinfo" do
     BasicSocket.do_not_reverse_lookup = @do_not_reverse_lookup
   end
 
-  platform_is_not :solaris, :windows do
+  platform_is_not :windows do
     it "gets the address information" do
       expected = []
       # The check for AP_INET6's class is needed because ipaddr.rb adds
@@ -43,7 +43,7 @@ describe "Socket.getaddrinfo" do
       addrinfo.each do |a|
         case a.last
         when Socket::IPPROTO_UDP, Socket::IPPROTO_TCP
-          expected.should include(a)
+          expected.should.include?(a)
         else
           # don't check this. It's some weird protocol we don't know about
           # so we can't spec it.
@@ -90,7 +90,7 @@ describe "Socket.getaddrinfo" do
         ["AF_INET6", 9, "::", "::", Socket::AF_INET6, Socket::SOCK_STREAM, Socket::IPPROTO_TCP],
         ["AF_INET6", 9, "0:0:0:0:0:0:0:0", "0:0:0:0:0:0:0:0", Socket::AF_INET6, Socket::SOCK_STREAM, Socket::IPPROTO_TCP]
       ]
-      res.each { |a| expected.should include(a) }
+      res.each { |a| expected.should.include?(a) }
     end
 
     it "accepts empty addresses for IPv6 non-passive sockets" do
@@ -104,7 +104,15 @@ describe "Socket.getaddrinfo" do
         ["AF_INET6", 9, "::1", "::1", Socket::AF_INET6, Socket::SOCK_STREAM, Socket::IPPROTO_TCP],
         ["AF_INET6", 9, "0:0:0:0:0:0:0:1", "0:0:0:0:0:0:0:1", Socket::AF_INET6, Socket::SOCK_STREAM, Socket::IPPROTO_TCP]
       ]
-      res.each { |a| expected.should include(a) }
+      res.each { |a| expected.should.include?(a) }
+    end
+
+    it "raises ResolutionError when fails to resolve address" do
+      -> {
+        Socket.getaddrinfo("www.kame.net", 80, "AF_UNIX")
+      }.should.raise(Socket::ResolutionError) { |e|
+        [Socket::EAI_FAMILY, Socket::EAI_FAIL].should.include?(e.error_code)
+      }
     end
   end
 end
@@ -112,7 +120,7 @@ end
 describe 'Socket.getaddrinfo' do
   describe 'without global reverse lookups' do
     it 'returns an Array' do
-      Socket.getaddrinfo(nil, 'ftp').should be_an_instance_of(Array)
+      Socket.getaddrinfo(nil, 'ftp').should.instance_of?(Array)
     end
 
     it 'accepts an Integer as the address family' do
@@ -123,8 +131,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '127.0.0.1'
       array[3].should == '127.0.0.1'
       array[4].should == Socket::AF_INET
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts an Integer as the address family using IPv6' do
@@ -135,8 +143,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '::1'
       array[3].should == '::1'
       array[4].should == Socket::AF_INET6
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts a Symbol as the address family' do
@@ -147,8 +155,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '127.0.0.1'
       array[3].should == '127.0.0.1'
       array[4].should == Socket::AF_INET
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts a Symbol as the address family using IPv6' do
@@ -159,8 +167,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '::1'
       array[3].should == '::1'
       array[4].should == Socket::AF_INET6
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts a String as the address family' do
@@ -171,8 +179,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '127.0.0.1'
       array[3].should == '127.0.0.1'
       array[4].should == Socket::AF_INET
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts a String as the address family using IPv6' do
@@ -183,8 +191,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '::1'
       array[3].should == '::1'
       array[4].should == Socket::AF_INET6
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts an object responding to #to_str as the host' do
@@ -199,8 +207,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '127.0.0.1'
       array[3].should == '127.0.0.1'
       array[4].should == Socket::AF_INET
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts an object responding to #to_str as the address family' do
@@ -215,8 +223,8 @@ describe 'Socket.getaddrinfo' do
       array[2].should == '127.0.0.1'
       array[3].should == '127.0.0.1'
       array[4].should == Socket::AF_INET
-      array[5].should be_kind_of(Integer)
-      array[6].should be_kind_of(Integer)
+      array[5].should.is_a?(Integer)
+      array[6].should.is_a?(Integer)
     end
 
     it 'accepts an Integer as the socket type' do
@@ -229,7 +237,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
 
     it 'accepts a Symbol as the socket type' do
@@ -242,7 +250,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
 
     it 'accepts a String as the socket type' do
@@ -255,7 +263,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
 
     it 'accepts an object responding to #to_str as the socket type' do
@@ -272,7 +280,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
 
     platform_is_not :windows do
@@ -286,7 +294,7 @@ describe 'Socket.getaddrinfo' do
           Socket::AF_INET,
           Socket::SOCK_DGRAM,
         ]
-        [0, Socket::IPPROTO_UDP].should include(proto)
+        [0, Socket::IPPROTO_UDP].should.include?(proto)
       end
     end
 
@@ -301,7 +309,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
 
     it 'performs a reverse lookup when the reverse_lookup argument is true' do
@@ -311,7 +319,7 @@ describe 'Socket.getaddrinfo' do
       addr[0].should == 'AF_INET'
       addr[1].should == 21
 
-      addr[2].should be_an_instance_of(String)
+      addr[2].should.instance_of?(String)
       addr[2].should_not == addr[3]
 
       addr[3].should == '127.0.0.1'
@@ -324,7 +332,7 @@ describe 'Socket.getaddrinfo' do
       addr[0].should == 'AF_INET'
       addr[1].should == 21
 
-      addr[2].should be_an_instance_of(String)
+      addr[2].should.instance_of?(String)
       addr[2].should_not == addr[3]
 
       addr[3].should == '127.0.0.1'
@@ -341,7 +349,7 @@ describe 'Socket.getaddrinfo' do
         Socket::AF_INET,
         Socket::SOCK_STREAM,
       ]
-      [0, Socket::IPPROTO_TCP].should include(proto)
+      [0, Socket::IPPROTO_TCP].should.include?(proto)
     end
   end
 
@@ -364,7 +372,7 @@ describe 'Socket.getaddrinfo' do
       # We don't have control over this value and there's no way to test this
       # without relying on Socket.getaddrinfo()'s own behaviour (meaning this
       # test would faily any way of the method was not implemented correctly).
-      addr[2].should be_an_instance_of(String)
+      addr[2].should.instance_of?(String)
       addr[2].should_not == addr[3]
 
       addr[3].should == '127.0.0.1'
diff --git a/spec/ruby/library/socket/socket/gethostbyaddr_spec.rb b/spec/ruby/library/socket/socket/gethostbyaddr_spec.rb
index 5d97341103..bf6d63dbe9 100644
--- a/spec/ruby/library/socket/socket/gethostbyaddr_spec.rb
+++ b/spec/ruby/library/socket/socket/gethostbyaddr_spec.rb
@@ -10,26 +10,23 @@ describe 'Socket.gethostbyaddr' do
 
     describe 'without an explicit address family' do
       it 'returns an Array' do
-        Socket.gethostbyaddr(@addr).should be_an_instance_of(Array)
+        suppress_warning { Socket.gethostbyaddr(@addr) }.should.instance_of?(Array)
       end
 
       describe 'the returned Array' do
         before do
-          @array = Socket.gethostbyaddr(@addr)
+          @array = suppress_warning { Socket.gethostbyaddr(@addr) }
         end
 
-        # RubyCI Solaris 11x defines 127.0.0.1 as unstable11x
-        platform_is_not :"solaris2.11" do
-          it 'includes the hostname as the first value' do
-            @array[0].should == SocketSpecs.hostname_reverse_lookup
-          end
+        it 'includes the hostname as the first value' do
+          @array[0].should == SocketSpecs.hostname_reverse_lookup
         end
 
         it 'includes the aliases as the 2nd value' do
-          @array[1].should be_an_instance_of(Array)
+          @array[1].should.instance_of?(Array)
 
           @array[1].each do |val|
-            val.should be_an_instance_of(String)
+            val.should.instance_of?(String)
           end
         end
 
@@ -41,7 +38,7 @@ describe 'Socket.gethostbyaddr' do
           @array[3].should == @addr
 
           @array[4..-1].each do |val|
-            val.should be_an_instance_of(String)
+            val.should.instance_of?(String)
           end
         end
       end
@@ -49,15 +46,15 @@ describe 'Socket.gethostbyaddr' do
 
     describe 'with an explicit address family' do
       it 'returns an Array when using an Integer as the address family' do
-        Socket.gethostbyaddr(@addr, Socket::AF_INET).should be_an_instance_of(Array)
+        suppress_warning { Socket.gethostbyaddr(@addr, Socket::AF_INET) }.should.instance_of?(Array)
       end
 
       it 'returns an Array when using a Symbol as the address family' do
-        Socket.gethostbyaddr(@addr, :INET).should be_an_instance_of(Array)
+        suppress_warning { Socket.gethostbyaddr(@addr, :INET) }.should.instance_of?(Array)
       end
 
       it 'raises SocketError when the address is not supported by the family' do
-        -> { Socket.gethostbyaddr(@addr, :INET6) }.should raise_error(SocketError)
+        -> { suppress_warning { Socket.gethostbyaddr(@addr, :INET6) } }.should.raise(SocketError)
       end
     end
   end
@@ -70,12 +67,12 @@ describe 'Socket.gethostbyaddr' do
 
       describe 'without an explicit address family' do
         it 'returns an Array' do
-          Socket.gethostbyaddr(@addr).should be_an_instance_of(Array)
+          suppress_warning { Socket.gethostbyaddr(@addr) }.should.instance_of?(Array)
         end
 
         describe 'the returned Array' do
           before do
-            @array = Socket.gethostbyaddr(@addr)
+            @array = suppress_warning { Socket.gethostbyaddr(@addr) }
           end
 
           it 'includes the hostname as the first value' do
@@ -83,10 +80,10 @@ describe 'Socket.gethostbyaddr' do
           end
 
           it 'includes the aliases as the 2nd value' do
-            @array[1].should be_an_instance_of(Array)
+            @array[1].should.instance_of?(Array)
 
             @array[1].each do |val|
-              val.should be_an_instance_of(String)
+              val.should.instance_of?(String)
             end
           end
 
@@ -95,10 +92,10 @@ describe 'Socket.gethostbyaddr' do
           end
 
           it 'includes all address strings as the remaining values' do
-            @array[3].should be_an_instance_of(String)
+            @array[3].should.instance_of?(String)
 
             @array[4..-1].each do |val|
-              val.should be_an_instance_of(String)
+              val.should.instance_of?(String)
             end
           end
         end
@@ -106,16 +103,16 @@ describe 'Socket.gethostbyaddr' do
 
       describe 'with an explicit address family' do
         it 'returns an Array when using an Integer as the address family' do
-          Socket.gethostbyaddr(@addr, Socket::AF_INET6).should be_an_instance_of(Array)
+          suppress_warning { Socket.gethostbyaddr(@addr, Socket::AF_INET6) }.should.instance_of?(Array)
         end
 
         it 'returns an Array when using a Symbol as the address family' do
-          Socket.gethostbyaddr(@addr, :INET6).should be_an_instance_of(Array)
+          suppress_warning { Socket.gethostbyaddr(@addr, :INET6) }.should.instance_of?(Array)
         end
 
-        platform_is_not :windows do
+        platform_is_not :windows, :wsl do
           it 'raises SocketError when the address is not supported by the family' do
-            -> { Socket.gethostbyaddr(@addr, :INET) }.should raise_error(SocketError)
+            -> { suppress_warning { Socket.gethostbyaddr(@addr, :INET) } }.should.raise(SocketError)
           end
         end
       end
diff --git a/spec/ruby/library/socket/socket/gethostbyname_spec.rb b/spec/ruby/library/socket/socket/gethostbyname_spec.rb
index 2696f44566..326fe26094 100644
--- a/spec/ruby/library/socket/socket/gethostbyname_spec.rb
+++ b/spec/ruby/library/socket/socket/gethostbyname_spec.rb
@@ -1,27 +1,27 @@
-# -*- encoding: binary -*-
+# encoding: binary
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "Socket.gethostbyname" do
   it "returns broadcast address info for '<broadcast>'" do
-    addr = Socket.gethostbyname('<broadcast>');
+    addr = suppress_warning { Socket.gethostbyname('<broadcast>') }
     addr.should == ["255.255.255.255", [], 2, "\xFF\xFF\xFF\xFF"]
   end
 
   it "returns broadcast address info for '<any>'" do
-    addr = Socket.gethostbyname('<any>');
+    addr = suppress_warning { Socket.gethostbyname('<any>') }
     addr.should == ["0.0.0.0", [], 2, "\x00\x00\x00\x00"]
   end
 end
 
 describe 'Socket.gethostbyname' do
   it 'returns an Array' do
-    Socket.gethostbyname('127.0.0.1').should be_an_instance_of(Array)
+    suppress_warning { Socket.gethostbyname('127.0.0.1') }.should.instance_of?(Array)
   end
 
   describe 'the returned Array' do
     before do
-      @array = Socket.gethostbyname('127.0.0.1')
+      @array = suppress_warning { Socket.gethostbyname('127.0.0.1') }
     end
 
     it 'includes the hostname as the first value' do
@@ -29,10 +29,10 @@ describe 'Socket.gethostbyname' do
     end
 
     it 'includes the aliases as the 2nd value' do
-      @array[1].should be_an_instance_of(Array)
+      @array[1].should.instance_of?(Array)
 
       @array[1].each do |val|
-        val.should be_an_instance_of(String)
+        val.should.instance_of?(String)
       end
     end
 
@@ -43,10 +43,10 @@ describe 'Socket.gethostbyname' do
     end
 
     it 'includes the address strings as the remaining values' do
-      @array[3].should be_an_instance_of(String)
+      @array[3].should.instance_of?(String)
 
       @array[4..-1].each do |val|
-        val.should be_an_instance_of(String)
+        val.should.instance_of?(String)
       end
     end
   end
@@ -54,7 +54,7 @@ describe 'Socket.gethostbyname' do
   describe 'using <broadcast> as the input address' do
     describe 'the returned Array' do
       before do
-        @addr = Socket.gethostbyname('<broadcast>')
+        @addr = suppress_warning { Socket.gethostbyname('<broadcast>') }
       end
 
       it 'includes the broadcast address as the first value' do
@@ -74,7 +74,7 @@ describe 'Socket.gethostbyname' do
   describe 'using <any> as the input address' do
     describe 'the returned Array' do
       before do
-        @addr = Socket.gethostbyname('<any>')
+        @addr = suppress_warning { Socket.gethostbyname('<any>') }
       end
 
       it 'includes the wildcard address as the first value' do
@@ -94,7 +94,7 @@ describe 'Socket.gethostbyname' do
   describe 'using an IPv4 address' do
     describe 'the returned Array' do
       before do
-        @addr = Socket.gethostbyname('127.0.0.1')
+        @addr = suppress_warning { Socket.gethostbyname('127.0.0.1') }
       end
 
       it 'includes the IP address as the first value' do
@@ -115,7 +115,7 @@ describe 'Socket.gethostbyname' do
     describe 'using an IPv6 address' do
       describe 'the returned Array' do
         before do
-          @addr = Socket.gethostbyname('::1')
+          @addr = suppress_warning { Socket.gethostbyname('::1') }
         end
 
         it 'includes the IP address as the first value' do
diff --git a/spec/ruby/library/socket/socket/gethostname_spec.rb b/spec/ruby/library/socket/socket/gethostname_spec.rb
index 4b79747b27..dfca7cf5cd 100644
--- a/spec/ruby/library/socket/socket/gethostname_spec.rb
+++ b/spec/ruby/library/socket/socket/gethostname_spec.rb
@@ -2,7 +2,17 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "Socket.gethostname" do
+  def system_hostname
+    if platform_is_not :windows
+      # `uname -n` is the most portable way to get the hostname, as it is a POSIX standard:
+      `uname -n`.strip
+    else
+      # Windows does not have uname, so we use hostname instead:
+      `hostname`.strip
+    end
+  end
+
   it "returns the host name" do
-    Socket.gethostname.should == `hostname`.strip
+    Socket.gethostname.should == system_hostname
   end
 end
diff --git a/spec/ruby/library/socket/socket/getifaddrs_spec.rb b/spec/ruby/library/socket/socket/getifaddrs_spec.rb
index 7df542abe6..1b326605c8 100644
--- a/spec/ruby/library/socket/socket/getifaddrs_spec.rb
+++ b/spec/ruby/library/socket/socket/getifaddrs_spec.rb
@@ -1,23 +1,23 @@
 require_relative '../spec_helper'
 
-platform_is_not :aix, :"solaris2.10" do
+platform_is_not :aix do
 describe 'Socket.getifaddrs' do
   before do
     @ifaddrs = Socket.getifaddrs
   end
 
   it 'returns an Array' do
-    @ifaddrs.should be_an_instance_of(Array)
+    @ifaddrs.should.instance_of?(Array)
   end
 
   describe 'the returned Array' do
     it 'should not be empty' do
-      @ifaddrs.should_not be_empty
+      @ifaddrs.should_not.empty?
     end
 
     it 'contains instances of Socket::Ifaddr' do
       @ifaddrs.each do |ifaddr|
-        ifaddr.should be_an_instance_of(Socket::Ifaddr)
+        ifaddr.should.instance_of?(Socket::Ifaddr)
       end
     end
   end
@@ -25,19 +25,19 @@ describe 'Socket.getifaddrs' do
   describe 'each returned Socket::Ifaddr' do
     it 'has an interface index' do
       @ifaddrs.each do |ifaddr|
-        ifaddr.ifindex.should be_kind_of(Integer)
+        ifaddr.ifindex.should.is_a?(Integer)
       end
     end
 
     it 'has an interface name' do
       @ifaddrs.each do |ifaddr|
-        ifaddr.name.should be_an_instance_of(String)
+        ifaddr.name.should.instance_of?(String)
       end
     end
 
     it 'has a set of flags' do
       @ifaddrs.each do |ifaddr|
-        ifaddr.flags.should be_kind_of(Integer)
+        ifaddr.flags.should.is_a?(Integer)
       end
     end
   end
@@ -49,17 +49,17 @@ describe 'Socket.getifaddrs' do
 
     it 'is an Addrinfo' do
       @addrs.all? do |addr|
-        addr.should be_an_instance_of(Addrinfo)
+        addr.should.instance_of?(Addrinfo)
         true
-      end.should be_true
+      end.should == true
     end
 
     it 'has an address family' do
       @addrs.all? do |addr|
-        addr.afamily.should be_kind_of(Integer)
+        addr.afamily.should.is_a?(Integer)
         addr.afamily.should_not == Socket::AF_UNSPEC
         true
-      end.should be_true
+      end.should == true
     end
   end
 
@@ -71,17 +71,17 @@ describe 'Socket.getifaddrs' do
 
       it 'is an Addrinfo' do
         @addrs.all? do |addr|
-          addr.should be_an_instance_of(Addrinfo)
+          addr.should.instance_of?(Addrinfo)
           true
-        end.should be_true
+        end.should == true
       end
 
       it 'has an address family' do
         @addrs.all? do |addr|
-          addr.afamily.should be_kind_of(Integer)
+          addr.afamily.should.is_a?(Integer)
           addr.afamily.should_not == Socket::AF_UNSPEC
           true
-        end.should be_true
+        end.should == true
       end
     end
 
@@ -92,24 +92,24 @@ describe 'Socket.getifaddrs' do
 
       it 'is an Addrinfo' do
         @addrs.all? do |addr|
-          addr.should be_an_instance_of(Addrinfo)
+          addr.should.instance_of?(Addrinfo)
           true
-        end.should be_true
+        end.should == true
       end
 
       it 'has an address family' do
         @addrs.all? do |addr|
-          addr.afamily.should be_kind_of(Integer)
+          addr.afamily.should.is_a?(Integer)
           addr.afamily.should_not == Socket::AF_UNSPEC
           true
-        end.should be_true
+        end.should == true
       end
 
       it 'has an IP address' do
         @addrs.all? do |addr|
-          addr.ip_address.should be_an_instance_of(String)
+          addr.ip_address.should.instance_of?(String)
           true
-        end.should be_true
+        end.should == true
       end
     end
   end
diff --git a/spec/ruby/library/socket/socket/getnameinfo_spec.rb b/spec/ruby/library/socket/socket/getnameinfo_spec.rb
index b406348aa8..d0b77004de 100644
--- a/spec/ruby/library/socket/socket/getnameinfo_spec.rb
+++ b/spec/ruby/library/socket/socket/getnameinfo_spec.rb
@@ -60,6 +60,14 @@ describe "Socket.getnameinfo" do
     name_info = Socket.getnameinfo ["AF_INET", 9, 'foo', '127.0.0.1']
     name_info[1].should == 'discard'
   end
+
+  it "raises ResolutionError when fails to resolve address" do
+    -> {
+      Socket.getnameinfo(["AF_UNIX", 80, "0.0.0.0"])
+    }.should.raise(Socket::ResolutionError) { |e|
+      [Socket::EAI_FAMILY, Socket::EAI_FAIL].should.include?(e.error_code)
+    }
+  end
 end
 
 describe 'Socket.getnameinfo' do
@@ -69,8 +77,8 @@ describe 'Socket.getnameinfo' do
     end
 
     it 'raises SocketError or TypeError when using an invalid String' do
-      -> { Socket.getnameinfo('cats') }.should raise_error(Exception) { |e|
-        [SocketError, TypeError].should include(e.class)
+      -> { Socket.getnameinfo('cats') }.should.raise(Exception) { |e|
+        (e.is_a?(SocketError) || e.is_a?(TypeError)).should == true
       }
     end
 
@@ -102,7 +110,7 @@ describe 'Socket.getnameinfo' do
       end
 
       it 'raises ArgumentError when using an invalid Array' do
-        -> { Socket.getnameinfo([family_name]) }.should raise_error(ArgumentError)
+        -> { Socket.getnameinfo([family_name]) }.should.raise(ArgumentError)
       end
 
       platform_is_not :windows do
@@ -122,7 +130,7 @@ describe 'Socket.getnameinfo' do
       describe 'without custom flags' do
         it 'returns an Array containing the hostname and service name' do
           array = Socket.getnameinfo(@addr)
-          array.should be_an_instance_of(Array)
+          array.should.instance_of?(Array)
           array[0].should == @hostname
           array[1].should == 'ftp'
         end
@@ -131,7 +139,7 @@ describe 'Socket.getnameinfo' do
           addr = [family_name, 21, ip_address, nil]
 
           array = Socket.getnameinfo(addr)
-          array.should be_an_instance_of(Array)
+          array.should.instance_of?(Array)
           array[0].should == @hostname
           array[1].should == 'ftp'
         end
diff --git a/spec/ruby/library/socket/socket/getservbyname_spec.rb b/spec/ruby/library/socket/socket/getservbyname_spec.rb
index d361e619f2..4a88444fff 100644
--- a/spec/ruby/library/socket/socket/getservbyname_spec.rb
+++ b/spec/ruby/library/socket/socket/getservbyname_spec.rb
@@ -27,6 +27,6 @@ describe "Socket#getservbyname" do
   end
 
   it "raises a SocketError when the service or port is invalid" do
-    -> { Socket.getservbyname('invalid') }.should raise_error(SocketError)
+    -> { Socket.getservbyname('invalid') }.should.raise(SocketError)
   end
 end
diff --git a/spec/ruby/library/socket/socket/getservbyport_spec.rb b/spec/ruby/library/socket/socket/getservbyport_spec.rb
index 563c592b54..7e4b75fa52 100644
--- a/spec/ruby/library/socket/socket/getservbyport_spec.rb
+++ b/spec/ruby/library/socket/socket/getservbyport_spec.rb
@@ -18,6 +18,6 @@ describe 'Socket.getservbyport' do
   end
 
   it 'raises SocketError for an unknown port number' do
-    -> { Socket.getservbyport(0) }.should raise_error(SocketError)
+    -> { Socket.getservbyport(0) }.should.raise(SocketError)
   end
 end
diff --git a/spec/ruby/library/socket/socket/initialize_spec.rb b/spec/ruby/library/socket/socket/initialize_spec.rb
index f8337bcaa5..a8fb1c61fa 100644
--- a/spec/ruby/library/socket/socket/initialize_spec.rb
+++ b/spec/ruby/library/socket/socket/initialize_spec.rb
@@ -13,7 +13,7 @@ describe 'Socket#initialize' do
     it 'returns a Socket' do
       @socket = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM)
 
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
   end
 
@@ -21,7 +21,7 @@ describe 'Socket#initialize' do
     it 'returns a Socket' do
       @socket = Socket.new(:INET, :STREAM)
 
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
   end
 
@@ -29,7 +29,7 @@ describe 'Socket#initialize' do
     it 'returns a Socket' do
       @socket = Socket.new('INET', 'STREAM')
 
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
   end
 
@@ -43,7 +43,7 @@ describe 'Socket#initialize' do
 
       @socket = Socket.new(family, type)
 
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
 
     it 'raises TypeError when the #to_str method does not return a String' do
@@ -53,7 +53,7 @@ describe 'Socket#initialize' do
       family.stub!(:to_str).and_return(Socket::AF_INET)
       type.stub!(:to_str).and_return(Socket::SOCK_STREAM)
 
-      -> { Socket.new(family, type) }.should raise_error(TypeError)
+      -> { Socket.new(family, type) }.should.raise(TypeError)
     end
   end
 
@@ -61,11 +61,11 @@ describe 'Socket#initialize' do
     it 'returns a Socket when using an Integer' do
       @socket = Socket.new(:INET, :STREAM, Socket::IPPROTO_TCP)
 
-      @socket.should be_an_instance_of(Socket)
+      @socket.should.instance_of?(Socket)
     end
 
     it 'raises TypeError when using a Symbol' do
-      -> { Socket.new(:INET, :STREAM, :TCP) }.should raise_error(TypeError)
+      -> { Socket.new(:INET, :STREAM, :TCP) }.should.raise(TypeError)
     end
   end
 
@@ -82,6 +82,6 @@ describe 'Socket#initialize' do
 
   it "sets the socket to binary mode" do
     @socket = Socket.new(:INET, :STREAM)
-    @socket.binmode?.should be_true
+    @socket.binmode?.should == true
   end
 end
diff --git a/spec/ruby/library/socket/socket/ip_address_list_spec.rb b/spec/ruby/library/socket/socket/ip_address_list_spec.rb
index f97c2d7f85..2c4e008af1 100644
--- a/spec/ruby/library/socket/socket/ip_address_list_spec.rb
+++ b/spec/ruby/library/socket/socket/ip_address_list_spec.rb
@@ -2,7 +2,7 @@ require_relative '../spec_helper'
 
 describe 'Socket.ip_address_list' do
   it 'returns an Array' do
-    Socket.ip_address_list.should be_an_instance_of(Array)
+    Socket.ip_address_list.should.instance_of?(Array)
   end
 
   describe 'the returned Array' do
@@ -11,12 +11,12 @@ describe 'Socket.ip_address_list' do
     end
 
     it 'is not empty' do
-      @array.should_not be_empty
+      @array.should_not.empty?
     end
 
     it 'contains Addrinfo objects' do
       @array.each do |klass|
-        klass.should be_an_instance_of(Addrinfo)
+        klass.should.instance_of?(Addrinfo)
       end
     end
   end
@@ -28,8 +28,8 @@ describe 'Socket.ip_address_list' do
 
     it 'has a non-empty IP address' do
       @array.each do |addr|
-        addr.ip_address.should be_an_instance_of(String)
-        addr.ip_address.should_not be_empty
+        addr.ip_address.should.instance_of?(String)
+        addr.ip_address.should_not.empty?
       end
     end
 
diff --git a/spec/ruby/library/socket/socket/listen_spec.rb b/spec/ruby/library/socket/socket/listen_spec.rb
index 5de70d6db0..7986a0225c 100644
--- a/spec/ruby/library/socket/socket/listen_spec.rb
+++ b/spec/ruby/library/socket/socket/listen_spec.rb
@@ -7,7 +7,7 @@ describe "Socket#listen" do
   end
 
   after :each do
-    @socket.closed?.should be_false
+    @socket.closed?.should == false
     @socket.close
   end
 
@@ -34,8 +34,10 @@ describe 'Socket#listen' do
         @server.close
       end
 
-      it 'raises Errno::EOPNOTSUPP' do
-        -> { @server.listen(1) }.should raise_error(Errno::EOPNOTSUPP)
+      it 'raises Errno::EOPNOTSUPP or Errno::EACCES' do
+        -> { @server.listen(1) }.should.raise { |e|
+          [Errno::EOPNOTSUPP, Errno::EACCES].should.include?(e.class)
+        }
       end
     end
 
@@ -57,7 +59,7 @@ describe 'Socket#listen' do
       end
 
       it "raises when the given argument can't be coerced to an Integer" do
-        -> { @server.listen('cats') }.should raise_error(TypeError)
+        -> { @server.listen('cats') }.should.raise(TypeError)
       end
     end
   end
diff --git a/spec/ruby/library/socket/socket/local_address_spec.rb b/spec/ruby/library/socket/socket/local_address_spec.rb
index 3687f93a0c..86b053fc3e 100644
--- a/spec/ruby/library/socket/socket/local_address_spec.rb
+++ b/spec/ruby/library/socket/socket/local_address_spec.rb
@@ -10,7 +10,7 @@ describe 'Socket#local_address' do
   end
 
   it 'returns an Addrinfo' do
-    @sock.local_address.should be_an_instance_of(Addrinfo)
+    @sock.local_address.should.instance_of?(Addrinfo)
   end
 
   describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/socket/new_spec.rb b/spec/ruby/library/socket/socket/new_spec.rb
deleted file mode 100644
index b2ec607f6a..0000000000
--- a/spec/ruby/library/socket/socket/new_spec.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-require_relative '../spec_helper'
-require_relative '../fixtures/classes'
diff --git a/spec/ruby/library/socket/socket/pack_sockaddr_in_spec.rb b/spec/ruby/library/socket/socket/pack_sockaddr_in_spec.rb
index 63d4724453..ef2a2d4ba9 100644
--- a/spec/ruby/library/socket/socket/pack_sockaddr_in_spec.rb
+++ b/spec/ruby/library/socket/socket/pack_sockaddr_in_spec.rb
@@ -2,6 +2,6 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 require_relative '../shared/pack_sockaddr'
 
-describe "Socket#pack_sockaddr_in" do
+describe "Socket.pack_sockaddr_in" do
   it_behaves_like :socket_pack_sockaddr_in, :pack_sockaddr_in
 end
diff --git a/spec/ruby/library/socket/socket/pair_spec.rb b/spec/ruby/library/socket/socket/pair_spec.rb
index 292eacd38d..8dd470a95e 100644
--- a/spec/ruby/library/socket/socket/pair_spec.rb
+++ b/spec/ruby/library/socket/socket/pair_spec.rb
@@ -2,6 +2,6 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 require_relative '../shared/socketpair'
 
-describe "Socket#pair" do
+describe "Socket.pair" do
   it_behaves_like :socket_socketpair, :pair
 end
diff --git a/spec/ruby/library/socket/socket/recvfrom_nonblock_spec.rb b/spec/ruby/library/socket/socket/recvfrom_nonblock_spec.rb
index 94f58ac49f..ab29435a1d 100644
--- a/spec/ruby/library/socket/socket/recvfrom_nonblock_spec.rb
+++ b/spec/ruby/library/socket/socket/recvfrom_nonblock_spec.rb
@@ -16,7 +16,7 @@ describe 'Socket#recvfrom_nonblock' do
     platform_is_not :windows do
       describe 'using an unbound socket' do
         it 'raises IO::WaitReadable' do
-          -> { @server.recvfrom_nonblock(1) }.should raise_error(IO::WaitReadable)
+          -> { @server.recvfrom_nonblock(1) }.should.raise(IO::WaitReadable)
         end
       end
     end
@@ -29,7 +29,7 @@ describe 'Socket#recvfrom_nonblock' do
 
       describe 'without any data available' do
         it 'raises IO::WaitReadable' do
-          -> { @server.recvfrom_nonblock(1) }.should raise_error(IO::WaitReadable)
+          -> { @server.recvfrom_nonblock(1) }.should.raise(IO::WaitReadable)
         end
 
         it 'returns :wait_readable with exception: false' do
@@ -47,11 +47,32 @@ describe 'Socket#recvfrom_nonblock' do
             IO.select([@server])
             ret = @server.recvfrom_nonblock(1)
 
-            ret.should be_an_instance_of(Array)
+            ret.should.instance_of?(Array)
             ret.length.should == 2
           end
         end
 
+        it "allows an output buffer as third argument" do
+          @client.write('hello')
+
+          IO.select([@server])
+          buffer = +''
+          message, = @server.recvfrom_nonblock(5, 0, buffer)
+
+          message.should.equal?(buffer)
+          buffer.should == 'hello'
+        end
+
+        it "preserves the encoding of the given buffer" do
+          @client.write('hello')
+
+          IO.select([@server])
+          buffer = ''.encode(Encoding::ISO_8859_1)
+          @server.recvfrom_nonblock(5, 0, buffer)
+
+          buffer.encoding.should == Encoding::ISO_8859_1
+        end
+
         describe 'the returned data' do
           it 'is the same as the sent data' do
             5.times do
@@ -77,7 +98,7 @@ describe 'Socket#recvfrom_nonblock' do
             end
 
             it 'contains an Addrinfo at index 1' do
-              @array[1].should be_an_instance_of(Addrinfo)
+              @array[1].should.instance_of?(Addrinfo)
             end
           end
 
@@ -116,3 +137,52 @@ describe 'Socket#recvfrom_nonblock' do
     end
   end
 end
+
+describe 'Socket#recvfrom_nonblock' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = Socket.new Socket::AF_INET, :STREAM, 0
+        @sockaddr = Socket.sockaddr_in(0, "127.0.0.1")
+        @server.bind(@sockaddr)
+        @server.listen(1)
+
+        server_ip    = @server.local_address.ip_port
+        @server_addr = Socket.sockaddr_in(server_ip, "127.0.0.1")
+
+        @client = Socket.new(Socket::AF_INET, :STREAM, 0)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      it "returns nil on a closed stream socket" do
+        ready = false
+
+        t = Thread.new do
+          client, _ = @server.accept
+
+          Thread.pass while !ready
+          begin
+            client.recvfrom_nonblock(10)
+          rescue IO::EAGAINWaitReadable
+            retry
+          end
+        ensure
+          client.close if client
+        end
+
+        Thread.pass while t.status and t.status != "sleep"
+        t.status.should_not == nil
+
+        @client.connect(@server_addr)
+        @client.close
+        ready = true
+
+        t.value.should == nil
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/socket/recvfrom_spec.rb b/spec/ruby/library/socket/socket/recvfrom_spec.rb
index faf161e4a5..0f319fc47c 100644
--- a/spec/ruby/library/socket/socket/recvfrom_spec.rb
+++ b/spec/ruby/library/socket/socket/recvfrom_spec.rb
@@ -39,7 +39,7 @@ describe 'Socket#recvfrom' do
         it 'returns an Array containing the data and an Addrinfo' do
           ret = @server.recvfrom(1)
 
-          ret.should be_an_instance_of(Array)
+          ret.should.instance_of?(Array)
           ret.length.should == 2
         end
 
@@ -53,7 +53,7 @@ describe 'Socket#recvfrom' do
           end
 
           it 'contains an Addrinfo at index 1' do
-            @array[1].should be_an_instance_of(Addrinfo)
+            @array[1].should.instance_of?(Addrinfo)
           end
         end
 
@@ -90,3 +90,68 @@ describe 'Socket#recvfrom' do
     end
   end
 end
+
+describe 'Socket#recvfrom' do
+  context "when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown)" do
+    describe "stream socket" do
+      before :each do
+        @server = Socket.new Socket::AF_INET, :STREAM, 0
+        sockaddr = Socket.sockaddr_in(0, "127.0.0.1")
+        @server.bind(sockaddr)
+        @server.listen(1)
+
+        server_ip    = @server.local_address.ip_port
+        @server_addr = Socket.sockaddr_in(server_ip, "127.0.0.1")
+
+        @client = Socket.new(Socket::AF_INET, :STREAM, 0)
+      end
+
+      after :each do
+        @server.close unless @server.closed?
+        @client.close unless @client.closed?
+      end
+
+      it "returns nil on a closed stream socket" do
+        t = Thread.new do
+          client, _ = @server.accept
+          client.recvfrom(10)
+        ensure
+          client.close if client
+        end
+
+        Thread.pass while t.status and t.status != "sleep"
+        t.status.should_not == nil
+
+        @client.connect(@server_addr)
+        @client.close
+
+        t.value.should == nil
+      end
+    end
+
+    describe "datagram socket" do
+      SocketSpecs.each_ip_protocol do |family, ip_address|
+        before :each do
+          @server = Socket.new(family, :DGRAM)
+          @client = Socket.new(family, :DGRAM)
+        end
+
+        after :each do
+          @server.close unless @server.closed?
+          @client.close unless @client.closed?
+        end
+
+        it "returns an empty String as received data" do
+          @server.bind(Socket.sockaddr_in(0, ip_address))
+          @client.connect(@server.getsockname)
+
+          @client.send('', 0)
+          message = @server.recvfrom(1)
+
+          message.should.is_a? Array
+          message[0].should == ""
+        end
+      end
+    end
+  end
+end
diff --git a/spec/ruby/library/socket/socket/remote_address_spec.rb b/spec/ruby/library/socket/socket/remote_address_spec.rb
index 24d60d7f58..f72ec50ed7 100644
--- a/spec/ruby/library/socket/socket/remote_address_spec.rb
+++ b/spec/ruby/library/socket/socket/remote_address_spec.rb
@@ -22,7 +22,7 @@ describe 'Socket#remote_address' do
     end
 
     it 'returns an Addrinfo' do
-      @client.remote_address.should be_an_instance_of(Addrinfo)
+      @client.remote_address.should.instance_of?(Addrinfo)
     end
 
     describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/socket/socketpair_spec.rb b/spec/ruby/library/socket/socket/socketpair_spec.rb
index 5b8311124e..551c376d49 100644
--- a/spec/ruby/library/socket/socket/socketpair_spec.rb
+++ b/spec/ruby/library/socket/socket/socketpair_spec.rb
@@ -2,6 +2,6 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 require_relative '../shared/socketpair'
 
-describe "Socket#socketpair" do
+describe "Socket.socketpair" do
   it_behaves_like :socket_socketpair, :socketpair
 end
diff --git a/spec/ruby/library/socket/socket/sysaccept_spec.rb b/spec/ruby/library/socket/socket/sysaccept_spec.rb
index 92ac21124e..3e7078f745 100644
--- a/spec/ruby/library/socket/socket/sysaccept_spec.rb
+++ b/spec/ruby/library/socket/socket/sysaccept_spec.rb
@@ -15,7 +15,7 @@ describe 'Socket#sysaccept' do
     platform_is :linux do # hangs on other platforms
       describe 'using an unbound socket'  do
         it 'raises Errno::EINVAL' do
-          -> { @server.sysaccept }.should raise_error(Errno::EINVAL)
+          -> { @server.sysaccept }.should.raise(Errno::EINVAL)
         end
       end
 
@@ -25,7 +25,7 @@ describe 'Socket#sysaccept' do
         end
 
         it 'raises Errno::EINVAL' do
-          -> { @server.sysaccept }.should raise_error(Errno::EINVAL)
+          -> { @server.sysaccept }.should.raise(Errno::EINVAL)
         end
       end
     end
@@ -59,7 +59,7 @@ describe 'Socket#sysaccept' do
 
           @client.connect(@server_addr)
 
-          thread.value.should be_an_instance_of(Array)
+          thread.value.should.instance_of?(Array)
         end
       end
 
@@ -76,8 +76,8 @@ describe 'Socket#sysaccept' do
         it 'returns an Array containing an Integer and an Addrinfo' do
           @fd, addrinfo = @server.sysaccept
 
-          @fd.should be_kind_of(Integer)
-          addrinfo.should be_an_instance_of(Addrinfo)
+          @fd.should.is_a?(Integer)
+          addrinfo.should.instance_of?(Addrinfo)
         end
 
         it 'returns a new file descriptor' do
diff --git a/spec/ruby/library/socket/socket/tcp_server_loop_spec.rb b/spec/ruby/library/socket/socket/tcp_server_loop_spec.rb
index a46c6df5c6..4e39d01d72 100644
--- a/spec/ruby/library/socket/socket/tcp_server_loop_spec.rb
+++ b/spec/ruby/library/socket/socket/tcp_server_loop_spec.rb
@@ -47,8 +47,8 @@ describe 'Socket.tcp_server_loop' do
       # complete.
       thread.join
 
-      @sock.should be_an_instance_of(Socket)
-      addr.should be_an_instance_of(Addrinfo)
+      @sock.should.instance_of?(Socket)
+      addr.should.instance_of?(Addrinfo)
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/tcp_server_sockets_spec.rb b/spec/ruby/library/socket/socket/tcp_server_sockets_spec.rb
index 10c030a8ce..b6cdb3c583 100644
--- a/spec/ruby/library/socket/socket/tcp_server_sockets_spec.rb
+++ b/spec/ruby/library/socket/socket/tcp_server_sockets_spec.rb
@@ -13,16 +13,16 @@ describe 'Socket.tcp_server_sockets' do
     it 'returns an Array of Socket objects' do
       @sockets = Socket.tcp_server_sockets(0)
 
-      @sockets.should be_an_instance_of(Array)
-      @sockets[0].should be_an_instance_of(Socket)
+      @sockets.should.instance_of?(Array)
+      @sockets[0].should.instance_of?(Socket)
     end
   end
 
   describe 'with a block' do
     it 'yields the sockets to the supplied block' do
       Socket.tcp_server_sockets(0) do |sockets|
-        sockets.should be_an_instance_of(Array)
-        sockets[0].should be_an_instance_of(Socket)
+        sockets.should.instance_of?(Array)
+        sockets[0].should.instance_of?(Socket)
       end
     end
 
@@ -32,7 +32,7 @@ describe 'Socket.tcp_server_sockets' do
       Socket.tcp_server_sockets(0) { |socks| sockets = socks }
 
       sockets.each do |socket|
-        socket.closed?.should == true
+        socket.should.closed?
       end
     end
   end
diff --git a/spec/ruby/library/socket/socket/tcp_spec.rb b/spec/ruby/library/socket/socket/tcp_spec.rb
index d36e3e6adb..cc3c9381c7 100644
--- a/spec/ruby/library/socket/socket/tcp_spec.rb
+++ b/spec/ruby/library/socket/socket/tcp_spec.rb
@@ -22,12 +22,12 @@ describe 'Socket.tcp' do
   it 'returns a Socket when no block is given' do
     @client = Socket.tcp(@host, @port)
 
-    @client.should be_an_instance_of(Socket)
+    @client.should.instance_of?(Socket)
   end
 
   it 'yields the Socket when a block is given' do
     Socket.tcp(@host, @port) do |socket|
-      socket.should be_an_instance_of(Socket)
+      socket.should.instance_of?(Socket)
     end
   end
 
@@ -36,7 +36,7 @@ describe 'Socket.tcp' do
       @socket = socket
     end
 
-    @socket.closed?.should == true
+    @socket.should.closed?
   end
 
   it 'binds to a local address and port when specified' do
@@ -51,20 +51,38 @@ describe 'Socket.tcp' do
   it 'raises ArgumentError when 6 arguments are provided' do
     -> {
       Socket.tcp(@host, @port, @host, 0, {:connect_timeout => 1}, 10)
-    }.should raise_error(ArgumentError)
+    }.should.raise(ArgumentError)
   end
 
   it 'connects to the server' do
     @client = Socket.tcp(@host, @port)
-
     @client.write('hello')
-
     connection, _ = @server.accept
-
     begin
       connection.recv(5).should == 'hello'
     ensure
       connection.close
     end
   end
+
+  ruby_version_is "4.0" do
+    it 'connects to the server when passed open_timeout argument' do
+      @client = Socket.tcp(@host, @port, open_timeout: 60)
+      @client.write('open_timeout')
+      connection, _ = @server.accept
+      begin
+        connection.recv(12).should == 'open_timeout'
+      ensure
+        connection.close
+      end
+    end
+
+    it 'raises Errno::ETIMEDOUT with :open_timeout when no server is listening on the given address' do
+      -> {
+        Socket.tcp("192.0.2.1", 80, open_timeout: 0)
+      }.should.raise(Errno::ETIMEDOUT)
+    rescue Errno::ENETUNREACH
+      skip "all network interfaces down"
+    end
+  end
 end
diff --git a/spec/ruby/library/socket/socket/udp_server_loop_on_spec.rb b/spec/ruby/library/socket/socket/udp_server_loop_on_spec.rb
index cb8c5c5587..9197509f1f 100644
--- a/spec/ruby/library/socket/socket/udp_server_loop_on_spec.rb
+++ b/spec/ruby/library/socket/socket/udp_server_loop_on_spec.rb
@@ -41,7 +41,7 @@ describe 'Socket.udp_server_loop_on' do
       end
 
       msg.should == 'hello'
-      src.should be_an_instance_of(Socket::UDPSource)
+      src.should.instance_of?(Socket::UDPSource)
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/udp_server_loop_spec.rb b/spec/ruby/library/socket/socket/udp_server_loop_spec.rb
index 66563bc742..d44d522c20 100644
--- a/spec/ruby/library/socket/socket/udp_server_loop_spec.rb
+++ b/spec/ruby/library/socket/socket/udp_server_loop_spec.rb
@@ -21,7 +21,7 @@ describe 'Socket.udp_server_loop' do
     it 'yields the message and a Socket::UDPSource' do
       msg, src = nil
 
-      Thread.new do
+      thread = Thread.new do
         SocketSpecs::ServerLoopPortFinder.udp_server_loop('127.0.0.1', 0) do |message, source|
           msg = message
           src = source
@@ -50,8 +50,10 @@ describe 'Socket.udp_server_loop' do
         end
       end
 
+      thread.join
+
       msg.should == 'hello'
-      src.should be_an_instance_of(Socket::UDPSource)
+      src.should.instance_of?(Socket::UDPSource)
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/udp_server_recv_spec.rb b/spec/ruby/library/socket/socket/udp_server_recv_spec.rb
index 47ed74bc03..34e2280558 100644
--- a/spec/ruby/library/socket/socket/udp_server_recv_spec.rb
+++ b/spec/ruby/library/socket/socket/udp_server_recv_spec.rb
@@ -30,6 +30,6 @@ describe 'Socket.udp_server_recv' do
     end
 
     msg.should == 'hello'
-    src.should be_an_instance_of(Socket::UDPSource)
+    src.should.instance_of?(Socket::UDPSource)
   end
 end
diff --git a/spec/ruby/library/socket/socket/udp_server_sockets_spec.rb b/spec/ruby/library/socket/socket/udp_server_sockets_spec.rb
index 3aeb472dda..cb357977d6 100644
--- a/spec/ruby/library/socket/socket/udp_server_sockets_spec.rb
+++ b/spec/ruby/library/socket/socket/udp_server_sockets_spec.rb
@@ -13,16 +13,16 @@ describe 'Socket.udp_server_sockets' do
     it 'returns an Array of Socket objects' do
       @sockets = Socket.udp_server_sockets(0)
 
-      @sockets.should be_an_instance_of(Array)
-      @sockets[0].should be_an_instance_of(Socket)
+      @sockets.should.instance_of?(Array)
+      @sockets[0].should.instance_of?(Socket)
     end
   end
 
   describe 'with a block' do
     it 'yields the sockets to the supplied block' do
       Socket.udp_server_sockets(0) do |sockets|
-        sockets.should be_an_instance_of(Array)
-        sockets[0].should be_an_instance_of(Socket)
+        sockets.should.instance_of?(Array)
+        sockets[0].should.instance_of?(Socket)
       end
     end
 
@@ -32,7 +32,7 @@ describe 'Socket.udp_server_sockets' do
       Socket.udp_server_sockets(0) { |socks| sockets = socks }
 
       sockets.each do |socket|
-        socket.closed?.should == true
+        socket.should.closed?
       end
     end
   end
diff --git a/spec/ruby/library/socket/socket/unix_server_loop_spec.rb b/spec/ruby/library/socket/socket/unix_server_loop_spec.rb
index 0f34d4a50b..9d35a995bc 100644
--- a/spec/ruby/library/socket/socket/unix_server_loop_spec.rb
+++ b/spec/ruby/library/socket/socket/unix_server_loop_spec.rb
@@ -1,58 +1,56 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'Socket.unix_server_loop' do
-    before do
-      @path = SocketSpecs.socket_path
-    end
+describe 'Socket.unix_server_loop' do
+  before do
+    @path = SocketSpecs.socket_path
+  end
 
-    after do
-      rm_r(@path) if File.file?(@path)
-    end
+  after do
+    rm_r(@path) if File.file?(@path)
+  end
 
-    describe 'when no connections are available' do
-      it 'blocks the caller' do
-        -> { Socket.unix_server_loop(@path) }.should block_caller
-      end
+  describe 'when no connections are available' do
+    it 'blocks the caller' do
+      -> { Socket.unix_server_loop(@path) }.should block_caller
     end
+  end
 
-    describe 'when a connection is available' do
-      before do
-        @client = nil
-      end
+  describe 'when a connection is available' do
+    before do
+      @client = nil
+    end
 
-      after do
-        @sock.close if @sock
-        @client.close if @client
-      end
+    after do
+      @sock.close if @sock
+      @client.close if @client
+    end
 
-      it 'yields a Socket and an Addrinfo' do
-        @sock, addr = nil
+    it 'yields a Socket and an Addrinfo' do
+      @sock, addr = nil
 
-        thread = Thread.new do
-          Socket.unix_server_loop(@path) do |socket, addrinfo|
-            @sock = socket
-            addr = addrinfo
+      thread = Thread.new do
+        Socket.unix_server_loop(@path) do |socket, addrinfo|
+          @sock = socket
+          addr = addrinfo
 
-            break
-          end
+          break
         end
+      end
 
-        SocketSpecs.loop_with_timeout do
-          begin
-            @client = Socket.unix(@path)
-          rescue SystemCallError
-            sleep 0.01
-            :retry
-          end
+      SocketSpecs.loop_with_timeout do
+        begin
+          @client = Socket.unix(@path)
+        rescue SystemCallError
+          sleep 0.01
+          :retry
         end
+      end
 
-        thread.join
+      thread.join
 
-        @sock.should be_an_instance_of(Socket)
-        addr.should be_an_instance_of(Addrinfo)
-      end
+      @sock.should.instance_of?(Socket)
+      addr.should.instance_of?(Addrinfo)
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/unix_server_socket_spec.rb b/spec/ruby/library/socket/socket/unix_server_socket_spec.rb
index fc357740fa..da9671bf8c 100644
--- a/spec/ruby/library/socket/socket/unix_server_socket_spec.rb
+++ b/spec/ruby/library/socket/socket/unix_server_socket_spec.rb
@@ -1,48 +1,46 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'Socket.unix_server_socket' do
+describe 'Socket.unix_server_socket' do
+  before do
+    @path = SocketSpecs.socket_path
+  end
+
+  after do
+    rm_r(@path)
+  end
+
+  describe 'when no block is given' do
     before do
-      @path = SocketSpecs.socket_path
+      @socket = nil
     end
 
     after do
-      rm_r(@path)
+      @socket.close
     end
 
-    describe 'when no block is given' do
-      before do
-        @socket = nil
-      end
-
-      after do
-        @socket.close
-      end
+    it 'returns a Socket' do
+      @socket = Socket.unix_server_socket(@path)
 
-      it 'returns a Socket' do
-        @socket = Socket.unix_server_socket(@path)
-
-        @socket.should be_an_instance_of(Socket)
-      end
+      @socket.should.instance_of?(Socket)
     end
+  end
 
-    describe 'when a block is given' do
-      it 'yields a Socket' do
-        Socket.unix_server_socket(@path) do |sock|
-          sock.should be_an_instance_of(Socket)
-        end
+  describe 'when a block is given' do
+    it 'yields a Socket' do
+      Socket.unix_server_socket(@path) do |sock|
+        sock.should.instance_of?(Socket)
       end
+    end
 
-      it 'closes the Socket when the block returns' do
-        socket = nil
-
-        Socket.unix_server_socket(@path) do |sock|
-          socket = sock
-        end
+    it 'closes the Socket when the block returns' do
+      socket = nil
 
-        socket.should be_an_instance_of(Socket)
+      Socket.unix_server_socket(@path) do |sock|
+        socket = sock
       end
+
+      socket.should.instance_of?(Socket)
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/unix_spec.rb b/spec/ruby/library/socket/socket/unix_spec.rb
index add54a097d..87f4938871 100644
--- a/spec/ruby/library/socket/socket/unix_spec.rb
+++ b/spec/ruby/library/socket/socket/unix_spec.rb
@@ -1,45 +1,43 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'Socket.unix' do
-    before do
-      @path   = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
-      @socket = nil
-    end
+describe 'Socket.unix' do
+  before do
+    @path   = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+    @socket = nil
+  end
 
-    after do
-      @server.close
-      @socket.close if @socket
+  after do
+    @server.close
+    @socket.close if @socket
 
-      rm_r(@path)
-    end
+    rm_r(@path)
+  end
 
-    describe 'when no block is given' do
-      it 'returns a Socket' do
-        @socket = Socket.unix(@path)
+  describe 'when no block is given' do
+    it 'returns a Socket' do
+      @socket = Socket.unix(@path)
 
-        @socket.should be_an_instance_of(Socket)
-      end
+      @socket.should.instance_of?(Socket)
     end
+  end
 
-    describe 'when a block is given' do
-      it 'yields a Socket' do
-        Socket.unix(@path) do |sock|
-          sock.should be_an_instance_of(Socket)
-        end
+  describe 'when a block is given' do
+    it 'yields a Socket' do
+      Socket.unix(@path) do |sock|
+        sock.should.instance_of?(Socket)
       end
+    end
 
-      it 'closes the Socket when the block returns' do
-        socket = nil
-
-        Socket.unix(@path) do |sock|
-          socket = sock
-        end
+    it 'closes the Socket when the block returns' do
+      socket = nil
 
-        socket.closed?.should == true
+      Socket.unix(@path) do |sock|
+        socket = sock
       end
+
+      socket.should.closed?
     end
   end
 end
diff --git a/spec/ruby/library/socket/socket/unpack_sockaddr_in_spec.rb b/spec/ruby/library/socket/socket/unpack_sockaddr_in_spec.rb
index 79ec68cd18..35d46b0fd0 100644
--- a/spec/ruby/library/socket/socket/unpack_sockaddr_in_spec.rb
+++ b/spec/ruby/library/socket/socket/unpack_sockaddr_in_spec.rb
@@ -32,15 +32,13 @@ describe "Socket.unpack_sockaddr_in" do
     end
   end
 
-  with_feature :unix_socket do
-    it "raises an ArgumentError when the sin_family is not AF_INET" do
-      sockaddr = Socket.sockaddr_un '/tmp/x'
-      -> { Socket.unpack_sockaddr_in sockaddr }.should raise_error(ArgumentError)
-    end
+  it "raises an ArgumentError when the sin_family is not AF_INET" do
+    sockaddr = Socket.sockaddr_un '/tmp/x'
+    -> { Socket.unpack_sockaddr_in sockaddr }.should.raise(ArgumentError)
+  end
 
-    it "raises an ArgumentError when passed addrinfo is not AF_INET/AF_INET6" do
-      addrinfo = Addrinfo.unix('/tmp/sock')
-      -> { Socket.unpack_sockaddr_in(addrinfo) }.should raise_error(ArgumentError)
-    end
+  it "raises an ArgumentError when passed addrinfo is not AF_INET/AF_INET6" do
+    addrinfo = Addrinfo.unix('/tmp/sock')
+    -> { Socket.unpack_sockaddr_in(addrinfo) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/socket/socket/unpack_sockaddr_un_spec.rb b/spec/ruby/library/socket/socket/unpack_sockaddr_un_spec.rb
index bd95f1db08..85a941cfc2 100644
--- a/spec/ruby/library/socket/socket/unpack_sockaddr_un_spec.rb
+++ b/spec/ruby/library/socket/socket/unpack_sockaddr_un_spec.rb
@@ -1,26 +1,24 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'Socket.unpack_sockaddr_un' do
-    it 'decodes sockaddr to unix path' do
-      sockaddr = Socket.sockaddr_un('/tmp/sock')
-      Socket.unpack_sockaddr_un(sockaddr).should == '/tmp/sock'
-    end
+describe 'Socket.unpack_sockaddr_un' do
+  it 'decodes sockaddr to unix path' do
+    sockaddr = Socket.sockaddr_un('/tmp/sock')
+    Socket.unpack_sockaddr_un(sockaddr).should == '/tmp/sock'
+  end
 
-    it 'returns unix path from a passed Addrinfo' do
-      addrinfo = Addrinfo.unix('/tmp/sock')
-      Socket.unpack_sockaddr_un(addrinfo).should == '/tmp/sock'
-    end
+  it 'returns unix path from a passed Addrinfo' do
+    addrinfo = Addrinfo.unix('/tmp/sock')
+    Socket.unpack_sockaddr_un(addrinfo).should == '/tmp/sock'
+  end
 
-    it 'raises an ArgumentError when the sin_family is not AF_UNIX' do
-      sockaddr = Socket.sockaddr_in(0, '127.0.0.1')
-      -> { Socket.unpack_sockaddr_un(sockaddr) }.should raise_error(ArgumentError)
-    end
+  it 'raises an ArgumentError when the sa_family is not AF_UNIX' do
+    sockaddr = Socket.sockaddr_in(0, '127.0.0.1')
+    -> { Socket.unpack_sockaddr_un(sockaddr) }.should.raise(ArgumentError)
+  end
 
-    it 'raises an ArgumentError when passed addrinfo is not AF_UNIX' do
-      addrinfo = Addrinfo.tcp('127.0.0.1', 0)
-      -> { Socket.unpack_sockaddr_un(addrinfo) }.should raise_error(ArgumentError)
-    end
+  it 'raises an ArgumentError when passed addrinfo is not AF_UNIX' do
+    addrinfo = Addrinfo.tcp('127.0.0.1', 0)
+    -> { Socket.unpack_sockaddr_un(addrinfo) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/library/socket/spec_helper.rb b/spec/ruby/library/socket/spec_helper.rb
index 1121542dd5..86f3a61086 100644
--- a/spec/ruby/library/socket/spec_helper.rb
+++ b/spec/ruby/library/socket/spec_helper.rb
@@ -1,13 +1,14 @@
 require_relative '../../spec_helper'
 require 'socket'
 
-MSpec.enable_feature :sock_packet if Socket.const_defined?(:SOCK_PACKET)
-MSpec.enable_feature :unix_socket unless PlatformGuard.windows?
-MSpec.enable_feature :udp_cork if Socket.const_defined?(:UDP_CORK)
-MSpec.enable_feature :tcp_cork if Socket.const_defined?(:TCP_CORK)
-MSpec.enable_feature :pktinfo if Socket.const_defined?(:IP_PKTINFO)
-MSpec.enable_feature :ipv6_pktinfo if Socket.const_defined?(:IPV6_PKTINFO)
-MSpec.enable_feature :ip_mtu if Socket.const_defined?(:IP_MTU)
-MSpec.enable_feature :ipv6_nexthop if Socket.const_defined?(:IPV6_NEXTHOP)
-MSpec.enable_feature :tcp_info if Socket.const_defined?(:TCP_INFO)
-MSpec.enable_feature :ancillary_data if Socket.const_defined?(:AncillaryData)
+# We force enable all features on Linux because anyway Linux implements all these features,
+# and we want a constant number of spec examples across Ruby implementations, even if they don't define these constants.
+MSpec.enable_feature :sock_packet    if platform_is(:linux) || Socket.const_defined?(:SOCK_PACKET)
+MSpec.enable_feature :udp_cork       if platform_is(:linux) || Socket.const_defined?(:UDP_CORK)
+MSpec.enable_feature :tcp_cork       if platform_is(:linux) || Socket.const_defined?(:TCP_CORK)
+MSpec.enable_feature :pktinfo        if platform_is(:linux) || Socket.const_defined?(:IP_PKTINFO)
+MSpec.enable_feature :ipv6_pktinfo   if platform_is(:linux) || Socket.const_defined?(:IPV6_PKTINFO)
+MSpec.enable_feature :ip_mtu         if platform_is(:linux) || Socket.const_defined?(:IP_MTU)
+MSpec.enable_feature :ipv6_nexthop   if platform_is(:linux) || Socket.const_defined?(:IPV6_NEXTHOP)
+MSpec.enable_feature :tcp_info       if platform_is(:linux) || Socket.const_defined?(:TCP_INFO)
+MSpec.enable_feature :ancillary_data if platform_is(:linux) || Socket.const_defined?(:AncillaryData)
diff --git a/spec/ruby/library/socket/tcpserver/accept_nonblock_spec.rb b/spec/ruby/library/socket/tcpserver/accept_nonblock_spec.rb
index 91f6a327f0..ac08fe37c6 100644
--- a/spec/ruby/library/socket/tcpserver/accept_nonblock_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/accept_nonblock_spec.rb
@@ -15,7 +15,7 @@ describe "Socket::TCPServer.accept_nonblock" do
     @server.listen(5)
     -> {
       @server.accept_nonblock
-    }.should raise_error(IO::WaitReadable)
+    }.should.raise(IO::WaitReadable)
 
     c = TCPSocket.new("127.0.0.1", @port)
     IO.select([@server])
@@ -25,7 +25,7 @@ describe "Socket::TCPServer.accept_nonblock" do
 
     port.should == @port
     address.should == "127.0.0.1"
-    s.should be_kind_of(TCPSocket)
+    s.should.is_a?(TCPSocket)
 
     c.close
     s.close
@@ -33,12 +33,12 @@ describe "Socket::TCPServer.accept_nonblock" do
 
   it "raises an IOError if the socket is closed" do
     @server.close
-    -> { @server.accept }.should raise_error(IOError)
+    -> { @server.accept }.should.raise(IOError)
   end
 
   describe 'without a connected client' do
     it 'raises error' do
-      -> { @server.accept_nonblock }.should raise_error(IO::WaitReadable)
+      -> { @server.accept_nonblock }.should.raise(IO::WaitReadable)
     end
 
     it 'returns :wait_readable in exceptionless mode' do
@@ -59,7 +59,7 @@ describe 'TCPServer#accept_nonblock' do
 
     describe 'without a connected client' do
       it 'raises IO::WaitReadable' do
-        -> { @server.accept_nonblock }.should raise_error(IO::WaitReadable)
+        -> { @server.accept_nonblock }.should.raise(IO::WaitReadable)
       end
     end
 
@@ -77,7 +77,7 @@ describe 'TCPServer#accept_nonblock' do
         it 'returns a TCPSocket' do
           IO.select([@server])
           @socket = @server.accept_nonblock
-          @socket.should be_an_instance_of(TCPSocket)
+          @socket.should.instance_of?(TCPSocket)
         end
       end
     end
diff --git a/spec/ruby/library/socket/tcpserver/accept_spec.rb b/spec/ruby/library/socket/tcpserver/accept_spec.rb
index 0da4e2218b..f2aa0bf8e1 100644
--- a/spec/ruby/library/socket/tcpserver/accept_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/accept_spec.rb
@@ -15,7 +15,7 @@ describe "TCPServer#accept" do
     data = nil
     t = Thread.new do
       client = @server.accept
-      client.should be_kind_of(TCPSocket)
+      client.should.is_a?(TCPSocket)
       data = client.read(5)
       client << "goodbye"
       client.close
@@ -50,7 +50,7 @@ describe "TCPServer#accept" do
     t = Thread.new {
       -> {
         @server.accept
-      }.should raise_error(Exception, "interrupted")
+      }.should.raise(Exception, "interrupted")
     }
 
     Thread.pass while t.status and t.status != "sleep"
@@ -58,9 +58,29 @@ describe "TCPServer#accept" do
     t.join
   end
 
+  it "is automatically retried when interrupted by SIGVTALRM" do
+    t = Thread.new do
+      client = @server.accept
+      value = client.read(2)
+      client.close
+      value
+    end
+
+    Thread.pass while t.status and t.status != "sleep"
+    # Thread#backtrace uses SIGVTALRM on TruffleRuby and potentially other implementations.
+    # Sending a signal to a thread is not possible with Ruby APIs.
+    t.backtrace.join("\n").should =~ /in [`'](?:TCPServer#)?accept'/
+
+    socket = TCPSocket.new('127.0.0.1', @port)
+    socket.write("OK")
+    socket.close
+
+    t.value.should == "OK"
+  end
+
   it "raises an IOError if the socket is closed" do
     @server.close
-    -> { @server.accept }.should raise_error(IOError)
+    -> { @server.accept }.should.raise(IOError)
   end
 end
 
@@ -92,7 +112,20 @@ describe 'TCPServer#accept' do
 
       it 'returns a TCPSocket' do
         @socket = @server.accept
-        @socket.should be_an_instance_of(TCPSocket)
+        @socket.should.instance_of?(TCPSocket)
+      end
+
+      platform_is_not :windows do
+        it "returns a TCPSocket which is set to nonblocking" do
+          require 'io/nonblock'
+          @socket = @server.accept
+          @socket.should.nonblock?
+        end
+      end
+
+      it "returns a TCPSocket which is set to close on exec" do
+        @socket = @server.accept
+        @socket.should.close_on_exec?
       end
     end
   end
diff --git a/spec/ruby/library/socket/tcpserver/gets_spec.rb b/spec/ruby/library/socket/tcpserver/gets_spec.rb
index 417976d737..72a72fa2dc 100644
--- a/spec/ruby/library/socket/tcpserver/gets_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/gets_spec.rb
@@ -11,6 +11,6 @@ describe "TCPServer#gets" do
   end
 
   it "raises Errno::ENOTCONN on gets" do
-    -> { @server.gets }.should raise_error(Errno::ENOTCONN)
+    -> { @server.gets }.should.raise(Errno::ENOTCONN)
   end
 end
diff --git a/spec/ruby/library/socket/tcpserver/initialize_spec.rb b/spec/ruby/library/socket/tcpserver/initialize_spec.rb
index 4ddd1f465f..517b014edc 100644
--- a/spec/ruby/library/socket/tcpserver/initialize_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/initialize_spec.rb
@@ -12,7 +12,7 @@ describe 'TCPServer#initialize' do
     end
 
     it 'sets the port to the given argument' do
-      @server.local_address.ip_port.should be_kind_of(Integer)
+      @server.local_address.ip_port.should.is_a?(Integer)
       @server.local_address.ip_port.should > 0
     end
 
@@ -24,7 +24,7 @@ describe 'TCPServer#initialize' do
     end
 
     it "sets the socket to binmode" do
-      @server.binmode?.should be_true
+      @server.binmode?.should == true
     end
   end
 
@@ -38,7 +38,7 @@ describe 'TCPServer#initialize' do
     end
 
     it 'sets the port to the given argument' do
-      @server.local_address.ip_port.should be_kind_of(Integer)
+      @server.local_address.ip_port.should.is_a?(Integer)
       @server.local_address.ip_port.should > 0
     end
 
@@ -52,7 +52,7 @@ describe 'TCPServer#initialize' do
 
   describe 'with a single String argument containing a non numeric value' do
     it 'raises SocketError' do
-      -> { TCPServer.new('cats') }.should raise_error(SocketError)
+      -> { TCPServer.new('cats') }.should.raise(SocketError)
     end
   end
 
@@ -67,7 +67,7 @@ describe 'TCPServer#initialize' do
       end
 
       it 'sets the port to the given port argument' do
-        @server.local_address.ip_port.should be_kind_of(Integer)
+        @server.local_address.ip_port.should.is_a?(Integer)
         @server.local_address.ip_port.should > 0
       end
 
@@ -90,7 +90,7 @@ describe 'TCPServer#initialize' do
     end
 
     it 'sets the port to the given port argument' do
-      @server.local_address.ip_port.should be_kind_of(Integer)
+      @server.local_address.ip_port.should.is_a?(Integer)
       @server.local_address.ip_port.should > 0
     end
 
diff --git a/spec/ruby/library/socket/tcpserver/listen_spec.rb b/spec/ruby/library/socket/tcpserver/listen_spec.rb
index c877fdced6..5b046ef6f7 100644
--- a/spec/ruby/library/socket/tcpserver/listen_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/listen_spec.rb
@@ -16,7 +16,7 @@ describe 'TCPServer#listen' do
     end
 
     it "raises when the given argument can't be coerced to an Integer" do
-      -> { @server.listen('cats') }.should raise_error(TypeError)
+      -> { @server.listen('cats') }.should.raise(TypeError)
     end
   end
 end
diff --git a/spec/ruby/library/socket/tcpserver/new_spec.rb b/spec/ruby/library/socket/tcpserver/new_spec.rb
index 94e5744995..70b8d4352e 100644
--- a/spec/ruby/library/socket/tcpserver/new_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/new_spec.rb
@@ -10,7 +10,7 @@ describe "TCPServer.new" do
     @server = TCPServer.new('127.0.0.1', 0)
     addr = @server.addr
     addr[0].should == 'AF_INET'
-    addr[1].should be_kind_of(Integer)
+    addr[1].should.is_a?(Integer)
     # on some platforms (Mac), MRI
     # returns comma at the end.
     addr[2].should =~ /^#{SocketSpecs.hostname}\b/
@@ -20,7 +20,7 @@ describe "TCPServer.new" do
   it "binds to localhost and a port with either IPv4 or IPv6" do
     @server = TCPServer.new(SocketSpecs.hostname, 0)
     addr = @server.addr
-    addr[1].should be_kind_of(Integer)
+    addr[1].should.is_a?(Integer)
     if addr[0] == 'AF_INET'
       addr[2].should =~ /^#{SocketSpecs.hostname}\b/
       addr[3].should == '127.0.0.1'
@@ -34,36 +34,77 @@ describe "TCPServer.new" do
     @server = TCPServer.new('', 0)
     addr = @server.addr
     addr[0].should == 'AF_INET'
-    addr[1].should be_kind_of(Integer)
+    addr[1].should.is_a?(Integer)
     addr[2].should == '0.0.0.0'
     addr[3].should == '0.0.0.0'
   end
 
   it "binds to INADDR_ANY if the hostname is empty and the port is a string" do
-    @server = TCPServer.new('', 0)
+    @server = TCPServer.new('', '0')
+    addr = @server.addr
+    addr[0].should == 'AF_INET'
+    addr[1].should.is_a?(Integer)
+    addr[2].should == '0.0.0.0'
+    addr[3].should == '0.0.0.0'
+  end
+
+  it "binds to a port if the port is explicitly nil" do
+    @server = TCPServer.new('', nil)
+    addr = @server.addr
+    addr[0].should == 'AF_INET'
+    addr[1].should.is_a?(Integer)
+    addr[2].should == '0.0.0.0'
+    addr[3].should == '0.0.0.0'
+  end
+
+  it "binds to a port if the port is an empty string" do
+    @server = TCPServer.new('', '')
     addr = @server.addr
     addr[0].should == 'AF_INET'
-    addr[1].should be_kind_of(Integer)
+    addr[1].should.is_a?(Integer)
     addr[2].should == '0.0.0.0'
     addr[3].should == '0.0.0.0'
   end
 
   it "coerces port to string, then determines port from that number or service name" do
-    -> { TCPServer.new(SocketSpecs.hostname, Object.new) }.should raise_error(TypeError)
+    -> { TCPServer.new(SocketSpecs.hostname, Object.new) }.should.raise(TypeError)
 
     port = Object.new
     port.should_receive(:to_str).and_return("0")
 
     @server = TCPServer.new(SocketSpecs.hostname, port)
     addr = @server.addr
-    addr[1].should be_kind_of(Integer)
+    addr[1].should.is_a?(Integer)
 
     # TODO: This should also accept strings like 'https', but I don't know how to
     # pick such a service port that will be able to reliably bind...
   end
 
+  it "has a single argument form and treats it as a port number" do
+    @server = TCPServer.new(0)
+    addr = @server.addr
+    addr[1].should.is_a?(Integer)
+  end
+
+  it "coerces port to a string when it is the only argument" do
+    -> { TCPServer.new(Object.new) }.should.raise(TypeError)
+
+    port = Object.new
+    port.should_receive(:to_str).and_return("0")
+
+    @server = TCPServer.new(port)
+    addr = @server.addr
+    addr[1].should.is_a?(Integer)
+  end
+
+  it "does not use the given block and warns to use TCPServer::open" do
+    -> {
+      @server = TCPServer.new(0) { raise }
+    }.should complain(/warning: TCPServer::new\(\) does not take block; use TCPServer::open\(\) instead/)
+  end
+
   it "raises Errno::EADDRNOTAVAIL when the address is unknown" do
-    -> { TCPServer.new("1.2.3.4", 0) }.should raise_error(Errno::EADDRNOTAVAIL)
+    -> { TCPServer.new("1.2.3.4", 0) }.should.raise(Errno::EADDRNOTAVAIL)
   end
 
   # There is no way to make this fail-proof on all machines, because
@@ -73,7 +114,7 @@ describe "TCPServer.new" do
     it "raises a SocketError when the host is unknown" do
       -> {
         TCPServer.new("--notavalidname", 0)
-      }.should raise_error(SocketError)
+      }.should.raise(SocketError)
     end
   end
 
@@ -81,7 +122,7 @@ describe "TCPServer.new" do
     @server = TCPServer.new('127.0.0.1', 0)
     -> {
       @server = TCPServer.new('127.0.0.1', @server.addr[1])
-    }.should raise_error(Errno::EADDRINUSE)
+    }.should.raise(Errno::EADDRINUSE)
   end
 
   platform_is_not :windows, :aix do
diff --git a/spec/ruby/library/socket/tcpserver/sysaccept_spec.rb b/spec/ruby/library/socket/tcpserver/sysaccept_spec.rb
index bd7d33faf4..ed23bced23 100644
--- a/spec/ruby/library/socket/tcpserver/sysaccept_spec.rb
+++ b/spec/ruby/library/socket/tcpserver/sysaccept_spec.rb
@@ -21,7 +21,7 @@ describe "TCPServer#sysaccept" do
 
       fd = @server.sysaccept
 
-      fd.should be_kind_of(Integer)
+      fd.should.is_a?(Integer)
     ensure
       sock.close if sock && !sock.closed?
       IO.for_fd(fd).close if fd
@@ -58,7 +58,7 @@ describe 'TCPServer#sysaccept' do
       it 'returns a new file descriptor as an Integer' do
         @fd = @server.sysaccept
 
-        @fd.should be_kind_of(Integer)
+        @fd.should.is_a?(Integer)
         @fd.should_not == @client.fileno
       end
     end
diff --git a/spec/ruby/library/socket/tcpsocket/gethostbyname_spec.rb b/spec/ruby/library/socket/tcpsocket/gethostbyname_spec.rb
index 703abff81c..c6fe007827 100644
--- a/spec/ruby/library/socket/tcpsocket/gethostbyname_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/gethostbyname_spec.rb
@@ -2,13 +2,15 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 # TODO: verify these for windows
-describe "TCPSocket#gethostbyname" do
+describe "TCPSocket.gethostbyname" do
   before :each do
-    @host_info = TCPSocket.gethostbyname(SocketSpecs.hostname)
+    suppress_warning do
+      @host_info = TCPSocket.gethostbyname(SocketSpecs.hostname)
+    end
   end
 
   it "returns an array elements of information on the hostname" do
-    @host_info.should be_kind_of(Array)
+    @host_info.should.is_a?(Array)
   end
 
   platform_is_not :windows do
@@ -18,12 +20,12 @@ describe "TCPSocket#gethostbyname" do
 
     it "returns the address type as the third value" do
       address_type = @host_info[2]
-      [Socket::AF_INET, Socket::AF_INET6].include?(address_type).should be_true
+      [Socket::AF_INET, Socket::AF_INET6].include?(address_type).should == true
     end
 
     it "returns the IP address as the fourth value" do
       ip = @host_info[3]
-      ["127.0.0.1", "::1"].include?(ip).should be_true
+      ["127.0.0.1", "::1"].include?(ip).should == true
     end
   end
 
@@ -46,19 +48,23 @@ describe "TCPSocket#gethostbyname" do
   end
 
   it "returns any aliases to the address as second value" do
-    @host_info[1].should be_kind_of(Array)
+    @host_info[1].should.is_a?(Array)
   end
 end
 
-describe 'TCPSocket#gethostbyname' do
+describe 'TCPSocket.gethostbyname' do
   it 'returns an Array' do
-    TCPSocket.gethostbyname('127.0.0.1').should be_an_instance_of(Array)
+    suppress_warning do
+      TCPSocket.gethostbyname('127.0.0.1').should.instance_of?(Array)
+    end
   end
 
   describe 'using a hostname' do
     describe 'the returned Array' do
       before do
-        @array = TCPSocket.gethostbyname('127.0.0.1')
+        suppress_warning do
+          @array = TCPSocket.gethostbyname('127.0.0.1')
+        end
       end
 
       it 'includes the canonical name as the 1st value' do
@@ -66,11 +72,11 @@ describe 'TCPSocket#gethostbyname' do
       end
 
       it 'includes an array of alternative hostnames as the 2nd value' do
-        @array[1].should be_an_instance_of(Array)
+        @array[1].should.instance_of?(Array)
       end
 
       it 'includes the address family as the 3rd value' do
-        @array[2].should be_kind_of(Integer)
+        @array[2].should.is_a?(Integer)
       end
 
       it 'includes the IP addresses as all the remaining values' do
@@ -88,7 +94,9 @@ describe 'TCPSocket#gethostbyname' do
   SocketSpecs.each_ip_protocol do |family, ip_address|
     describe 'the returned Array' do
       before do
-        @array = TCPSocket.gethostbyname(ip_address)
+        suppress_warning do
+          @array = TCPSocket.gethostbyname(ip_address)
+        end
       end
 
       it 'includes the IP address as the 1st value' do
diff --git a/spec/ruby/library/socket/tcpsocket/initialize_spec.rb b/spec/ruby/library/socket/tcpsocket/initialize_spec.rb
index a3cee05412..a33d0b16ba 100644
--- a/spec/ruby/library/socket/tcpsocket/initialize_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/initialize_spec.rb
@@ -1,11 +1,37 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
+require_relative 'shared/new'
+
+describe 'TCPSocket#initialize' do
+  it_behaves_like :tcpsocket_new, :new
+
+  describe "with a running server" do
+    before :each do
+      @server = SocketSpecs::SpecTCPServer.new
+      @hostname = @server.hostname
+    end
+
+    after :each do
+      if @socket
+        @socket.write "QUIT"
+        @socket.close
+      end
+      @server.shutdown
+    end
+
+    it "does not use the given block and warns to use TCPSocket::open" do
+      -> {
+        @socket = TCPSocket.new(@hostname, @server.port, nil) { raise }
+      }.should complain(/warning: TCPSocket::new\(\) does not take block; use TCPSocket::open\(\) instead/)
+    end
+  end
+end
 
 describe 'TCPSocket#initialize' do
   SocketSpecs.each_ip_protocol do |family, ip_address|
     describe 'when no server is listening on the given address' do
       it 'raises Errno::ECONNREFUSED' do
-        -> { TCPSocket.new(ip_address, 666) }.should raise_error(Errno::ECONNREFUSED)
+        -> { TCPSocket.new(ip_address, 666) }.should.raise(Errno::ECONNREFUSED)
       end
     end
 
@@ -22,21 +48,21 @@ describe 'TCPSocket#initialize' do
 
       it 'returns a TCPSocket when using an Integer as the port' do
         @client = TCPSocket.new(ip_address, @port)
-        @client.should be_an_instance_of(TCPSocket)
+        @client.should.instance_of?(TCPSocket)
       end
 
       it 'returns a TCPSocket when using a String as the port' do
         @client = TCPSocket.new(ip_address, @port.to_s)
-        @client.should be_an_instance_of(TCPSocket)
+        @client.should.instance_of?(TCPSocket)
       end
 
       it 'raises SocketError when the port number is a non numeric String' do
-        -> { TCPSocket.new(ip_address, 'cats') }.should raise_error(SocketError)
+        -> { TCPSocket.new(ip_address, 'cats') }.should.raise(SocketError)
       end
 
       it 'set the socket to binmode' do
         @client = TCPSocket.new(ip_address, @port)
-        @client.binmode?.should be_true
+        @client.binmode?.should == true
       end
 
       it 'connects to the right address' do
@@ -46,6 +72,19 @@ describe 'TCPSocket#initialize' do
         @client.remote_address.ip_port.should    == @server.local_address.ip_port
       end
 
+      platform_is_not :windows do
+        it "creates a socket which is set to nonblocking" do
+          require 'io/nonblock'
+          @client = TCPSocket.new(ip_address, @port)
+          @client.should.nonblock?
+        end
+      end
+
+      it "creates a socket which is set to close on exec" do
+        @client = TCPSocket.new(ip_address, @port)
+        @client.should.close_on_exec?
+      end
+
       describe 'using a local address and service' do
         it 'binds the client socket to the local address and service' do
           @client = TCPSocket.new(ip_address, @port, ip_address, 0)
diff --git a/spec/ruby/library/socket/tcpsocket/local_address_spec.rb b/spec/ruby/library/socket/tcpsocket/local_address_spec.rb
index ce66d5ff8f..5dcf741f29 100644
--- a/spec/ruby/library/socket/tcpsocket/local_address_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/local_address_spec.rb
@@ -23,7 +23,7 @@ describe 'TCPSocket#local_address' do
       end
 
       it 'returns an Addrinfo' do
-        @sock.local_address.should be_an_instance_of(Addrinfo)
+        @sock.local_address.should.instance_of?(Addrinfo)
       end
 
       describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/tcpsocket/new_spec.rb b/spec/ruby/library/socket/tcpsocket/new_spec.rb
deleted file mode 100644
index 4924468be7..0000000000
--- a/spec/ruby/library/socket/tcpsocket/new_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require_relative 'shared/new'
-
-describe "TCPSocket.new" do
-  it_behaves_like :tcpsocket_new, :new
-end
diff --git a/spec/ruby/library/socket/tcpsocket/open_spec.rb b/spec/ruby/library/socket/tcpsocket/open_spec.rb
index 31b630a23b..0c0b579064 100644
--- a/spec/ruby/library/socket/tcpsocket/open_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/open_spec.rb
@@ -1,3 +1,4 @@
+require_relative "../../../spec_helper"
 require_relative 'shared/new'
 
 describe "TCPSocket.open" do
diff --git a/spec/ruby/library/socket/tcpsocket/partially_closable_spec.rb b/spec/ruby/library/socket/tcpsocket/partially_closable_spec.rb
index a381627a39..d365ecd335 100644
--- a/spec/ruby/library/socket/tcpsocket/partially_closable_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/partially_closable_spec.rb
@@ -16,6 +16,6 @@ describe "TCPSocket partial closability" do
     @s2.close
   end
 
-  it_should_behave_like "partially closable sockets"
+  it_should_behave_like :partially_closable_sockets
 
 end
diff --git a/spec/ruby/library/socket/tcpsocket/recv_nonblock_spec.rb b/spec/ruby/library/socket/tcpsocket/recv_nonblock_spec.rb
index bfd815c658..6ce5a41b58 100644
--- a/spec/ruby/library/socket/tcpsocket/recv_nonblock_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/recv_nonblock_spec.rb
@@ -27,6 +27,20 @@ describe "TCPSocket#recv_nonblock" do
     @socket.recv_nonblock(50).should == "TCPSocket#recv_nonblock"
   end
 
+  it 'writes the read to a buffer from the socket' do
+    @socket = TCPSocket.new @hostname, @server.port
+    @socket.write "TCPSocket#recv_nonblock"
+
+    # Wait for the server to echo. This spec is testing the return
+    # value, not the non-blocking behavior.
+    #
+    # TODO: Figure out a good way to test non-blocking.
+    IO.select([@socket])
+    buffer = "".b
+    @socket.recv_nonblock(50, 0, buffer)
+    buffer.should == 'TCPSocket#recv_nonblock'
+  end
+
   it 'returns :wait_readable in exceptionless mode' do
     @socket = TCPSocket.new @hostname, @server.port
     @socket.recv_nonblock(50, exception: false).should == :wait_readable
diff --git a/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb b/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb
index eb9dabc075..085d57b3f9 100644
--- a/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb
+++ b/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb
@@ -23,7 +23,7 @@ describe 'TCPSocket#remote_address' do
       end
 
       it 'returns an Addrinfo' do
-        @sock.remote_address.should be_an_instance_of(Addrinfo)
+        @sock.remote_address.should.instance_of?(Addrinfo)
       end
 
       describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/tcpsocket/shared/new.rb b/spec/ruby/library/socket/tcpsocket/shared/new.rb
index 5ca3a0e6cc..9c15dced4f 100644
--- a/spec/ruby/library/socket/tcpsocket/shared/new.rb
+++ b/spec/ruby/library/socket/tcpsocket/shared/new.rb
@@ -3,17 +3,35 @@ require_relative '../../fixtures/classes'
 
 describe :tcpsocket_new, shared: true do
   it "requires a hostname and a port as arguments" do
-    -> { TCPSocket.send(@method) }.should raise_error(ArgumentError)
+    -> { TCPSocket.send(@method) }.should.raise(ArgumentError)
   end
 
   it "refuses the connection when there is no server to connect to" do
     -> do
       TCPSocket.send(@method, SocketSpecs.hostname, SocketSpecs.reserved_unused_port)
-    end.should raise_error(SystemCallError) {|e|
-      [Errno::ECONNREFUSED, Errno::EADDRNOTAVAIL].should include(e.class)
+    end.should.raise(SystemCallError) {|e|
+      [Errno::ECONNREFUSED, Errno::EADDRNOTAVAIL].should.include?(e.class)
     }
   end
 
+  it 'raises IO::TimeoutError with :connect_timeout when no server is listening on the given address' do
+    -> {
+      TCPSocket.send(@method, "192.0.2.1", 80, connect_timeout: 0)
+    }.should.raise(IO::TimeoutError)
+  rescue Errno::ENETUNREACH
+    skip "all network interfaces down"
+  end
+
+  ruby_version_is "4.0" do
+    it 'raises IO::TimeoutError with :open_timeout when no server is listening on the given address' do
+      -> {
+        TCPSocket.send(@method, "192.0.2.1", 80, open_timeout: 0)
+      }.should.raise(IO::TimeoutError)
+    rescue Errno::ENETUNREACH
+      skip "all network interfaces down"
+    end
+  end
+
   describe "with a running server" do
     before :each do
       @server = SocketSpecs::SpecTCPServer.new
@@ -30,34 +48,43 @@ describe :tcpsocket_new, shared: true do
 
     it "silently ignores 'nil' as the third parameter" do
       @socket = TCPSocket.send(@method, @hostname, @server.port, nil)
-      @socket.should be_an_instance_of(TCPSocket)
+      @socket.should.instance_of?(TCPSocket)
     end
 
     it "connects to a listening server with host and port" do
       @socket = TCPSocket.send(@method, @hostname, @server.port)
-      @socket.should be_an_instance_of(TCPSocket)
+      @socket.should.instance_of?(TCPSocket)
     end
 
     it "connects to a server when passed local_host argument" do
       @socket = TCPSocket.send(@method, @hostname, @server.port, @hostname)
-      @socket.should be_an_instance_of(TCPSocket)
+      @socket.should.instance_of?(TCPSocket)
     end
 
     it "connects to a server when passed local_host and local_port arguments" do
-      server = TCPServer.new(SocketSpecs.hostname, 0)
+      retries = 0
+      max_retries = 3
+
       begin
-        available_port = server.addr[1]
-      ensure
-        server.close
+        retries += 1
+        server = TCPServer.new(SocketSpecs.hostname, 0)
+        begin
+          available_port = server.addr[1]
+        ensure
+          server.close
+        end
+        @socket = TCPSocket.send(@method, @hostname, @server.port,
+                                 @hostname, available_port)
+      rescue Errno::EADDRINUSE
+        raise if retries >= max_retries
+        retry
       end
-      @socket = TCPSocket.send(@method, @hostname, @server.port,
-                               @hostname, available_port)
-      @socket.should be_an_instance_of(TCPSocket)
+      @socket.should.instance_of?(TCPSocket)
     end
 
     it "has an address once it has connected to a listening server" do
       @socket = TCPSocket.send(@method, @hostname, @server.port)
-      @socket.should be_an_instance_of(TCPSocket)
+      @socket.should.instance_of?(TCPSocket)
 
       # TODO: Figure out how to abstract this. You can get AF_INET
       # from 'Socket.getaddrinfo(hostname, nil)[0][3]' but socket.addr
@@ -72,8 +99,20 @@ describe :tcpsocket_new, shared: true do
         @socket.addr[3].should == SocketSpecs.addr(:ipv6)
       end
 
-      @socket.addr[1].should be_kind_of(Integer)
+      @socket.addr[1].should.is_a?(Integer)
       @socket.addr[2].should =~ /^#{@hostname}/
     end
+
+    it "connects to a server when passed connect_timeout argument" do
+      @socket = TCPSocket.send(@method, @hostname, @server.port, connect_timeout: 1)
+      @socket.should.instance_of?(TCPSocket)
+    end
+
+    ruby_version_is "4.0" do
+      it "connects to a server when passed open_timeout argument" do
+        @socket = TCPSocket.send(@method, @hostname, @server.port, open_timeout: 1)
+        @socket.should.instance_of?(TCPSocket)
+      end
+    end
   end
 end
diff --git a/spec/ruby/library/socket/udpsocket/bind_spec.rb b/spec/ruby/library/socket/udpsocket/bind_spec.rb
index 08b386e941..974e701e71 100644
--- a/spec/ruby/library/socket/udpsocket/bind_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/bind_spec.rb
@@ -12,7 +12,7 @@ describe "UDPSocket#bind" do
 
   it "binds the socket to a port" do
     @socket.bind(SocketSpecs.hostname, 0)
-    @socket.addr[1].should be_kind_of(Integer)
+    @socket.addr[1].should.is_a?(Integer)
   end
 
   it "raises Errno::EINVAL when already bound" do
@@ -20,7 +20,7 @@ describe "UDPSocket#bind" do
 
     -> {
       @socket.bind(SocketSpecs.hostname, @socket.addr[1])
-    }.should raise_error(Errno::EINVAL)
+    }.should.raise(Errno::EINVAL)
   end
 
   it "receives a hostname and a port" do
diff --git a/spec/ruby/library/socket/udpsocket/initialize_spec.rb b/spec/ruby/library/socket/udpsocket/initialize_spec.rb
index 1d635149f7..c040187400 100644
--- a/spec/ruby/library/socket/udpsocket/initialize_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/initialize_spec.rb
@@ -7,34 +7,47 @@ describe 'UDPSocket#initialize' do
 
   it 'initializes a new UDPSocket' do
     @socket = UDPSocket.new
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'initializes a new UDPSocket using an Integer' do
     @socket = UDPSocket.new(Socket::AF_INET)
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'initializes a new UDPSocket using a Symbol' do
     @socket = UDPSocket.new(:INET)
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'initializes a new UDPSocket using a String' do
     @socket = UDPSocket.new('INET')
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'sets the socket to binmode' do
     @socket = UDPSocket.new(:INET)
-    @socket.binmode?.should be_true
+    @socket.binmode?.should == true
+  end
+
+  platform_is_not :windows do
+    it 'sets the socket to nonblock' do
+      require 'io/nonblock'
+      @socket = UDPSocket.new(:INET)
+      @socket.should.nonblock?
+    end
+  end
+
+  it 'sets the socket to close on exec' do
+    @socket = UDPSocket.new(:INET)
+    @socket.should.close_on_exec?
   end
 
   it 'raises Errno::EAFNOSUPPORT or Errno::EPROTONOSUPPORT when given an invalid address family' do
     -> {
       UDPSocket.new(666)
-    }.should raise_error(SystemCallError) { |e|
-      [Errno::EAFNOSUPPORT, Errno::EPROTONOSUPPORT].should include(e.class)
+    }.should.raise(SystemCallError) { |e|
+      [Errno::EAFNOSUPPORT, Errno::EPROTONOSUPPORT].should.include?(e.class)
     }
   end
 end
diff --git a/spec/ruby/library/socket/udpsocket/inspect_spec.rb b/spec/ruby/library/socket/udpsocket/inspect_spec.rb
deleted file mode 100644
index 201e8b3fc6..0000000000
--- a/spec/ruby/library/socket/udpsocket/inspect_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-require_relative '../spec_helper'
-
-describe 'UDPSocket#inspect' do
-  before do
-    @socket = UDPSocket.new
-    @socket.bind('127.0.0.1', 0)
-  end
-
-  after do
-    @socket.close
-  end
-
-  ruby_version_is ""..."2.5" do
-    it 'returns a String with the fd' do
-      @socket.inspect.should == "#<UDPSocket:fd #{@socket.fileno}>"
-    end
-  end
-
-  ruby_version_is "2.5" do
-    it 'returns a String with the fd, family, address and port' do
-      port = @socket.addr[1]
-      @socket.inspect.should == "#<UDPSocket:fd #{@socket.fileno}, AF_INET, 127.0.0.1, #{port}>"
-    end
-  end
-end
diff --git a/spec/ruby/library/socket/udpsocket/local_address_spec.rb b/spec/ruby/library/socket/udpsocket/local_address_spec.rb
index 92e4cc10c7..868d2f537e 100644
--- a/spec/ruby/library/socket/udpsocket/local_address_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/local_address_spec.rb
@@ -28,7 +28,7 @@ describe 'UDPSocket#local_address' do
       end
 
       it 'returns an Addrinfo' do
-        @sock.local_address.should be_an_instance_of(Addrinfo)
+        @sock.local_address.should.instance_of?(Addrinfo)
       end
 
       describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/udpsocket/new_spec.rb b/spec/ruby/library/socket/udpsocket/new_spec.rb
index 6cc0cadbcb..aff111927c 100644
--- a/spec/ruby/library/socket/udpsocket/new_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/new_spec.rb
@@ -8,27 +8,33 @@ describe 'UDPSocket.new' do
 
   it 'without arguments' do
     @socket = UDPSocket.new
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'using Integer argument' do
     @socket = UDPSocket.new(Socket::AF_INET)
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'using Symbol argument' do
     @socket = UDPSocket.new(:INET)
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
   end
 
   it 'using String argument' do
     @socket = UDPSocket.new('INET')
-    @socket.should be_an_instance_of(UDPSocket)
+    @socket.should.instance_of?(UDPSocket)
+  end
+
+  it "does not use the given block and warns to use UDPSocket::open" do
+    -> {
+      @socket = UDPSocket.new { raise }
+    }.should complain(/warning: UDPSocket::new\(\) does not take block; use UDPSocket::open\(\) instead/)
   end
 
   it 'raises Errno::EAFNOSUPPORT or Errno::EPROTONOSUPPORT if unsupported family passed' do
-    -> { UDPSocket.new(-1) }.should raise_error(SystemCallError) { |e|
-      [Errno::EAFNOSUPPORT, Errno::EPROTONOSUPPORT].should include(e.class)
+    -> { UDPSocket.new(-1) }.should.raise(SystemCallError) { |e|
+      [Errno::EAFNOSUPPORT, Errno::EPROTONOSUPPORT].should.include?(e.class)
     }
   end
 end
diff --git a/spec/ruby/library/socket/udpsocket/open_spec.rb b/spec/ruby/library/socket/udpsocket/open_spec.rb
index e4dbb2ee2a..7c77855372 100644
--- a/spec/ruby/library/socket/udpsocket/open_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/open_spec.rb
@@ -8,6 +8,6 @@ describe "UDPSocket.open" do
 
   it "allows calls to open without arguments" do
     @socket = UDPSocket.open
-    @socket.should be_kind_of(UDPSocket)
+    @socket.should.is_a?(UDPSocket)
   end
 end
diff --git a/spec/ruby/library/socket/udpsocket/recvfrom_nonblock_spec.rb b/spec/ruby/library/socket/udpsocket/recvfrom_nonblock_spec.rb
index c66d1df84d..460cf2c9a2 100644
--- a/spec/ruby/library/socket/udpsocket/recvfrom_nonblock_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/recvfrom_nonblock_spec.rb
@@ -16,7 +16,7 @@ describe 'UDPSocket#recvfrom_nonblock' do
     platform_is_not :windows do
       describe 'using an unbound socket' do
         it 'raises IO::WaitReadable' do
-          -> { @server.recvfrom_nonblock(1) }.should raise_error(IO::WaitReadable)
+          -> { @server.recvfrom_nonblock(1) }.should.raise(IO::WaitReadable)
         end
       end
     end
@@ -32,7 +32,7 @@ describe 'UDPSocket#recvfrom_nonblock' do
 
       describe 'without any data available' do
         it 'raises IO::WaitReadable' do
-          -> { @server.recvfrom_nonblock(1) }.should raise_error(IO::WaitReadable)
+          -> { @server.recvfrom_nonblock(1) }.should.raise(IO::WaitReadable)
         end
 
         it 'returns :wait_readable with exception: false' do
@@ -48,7 +48,23 @@ describe 'UDPSocket#recvfrom_nonblock' do
 
           it 'returns an Array containing the data and an Array' do
             IO.select([@server])
-            @server.recvfrom_nonblock(1).should be_an_instance_of(Array)
+            @server.recvfrom_nonblock(1).should.instance_of?(Array)
+          end
+
+          it 'writes the data to the buffer when one is present' do
+            buffer = "".b
+            IO.select([@server])
+            @server.recvfrom_nonblock(1, 0, buffer)
+            buffer.should == 'h'
+          end
+
+          it "preserves the encoding of the given buffer" do
+            buffer = ''.encode(Encoding::ISO_8859_1)
+            IO.select([@server])
+            message, = @server.recvfrom_nonblock(1, 0, buffer)
+
+            message.should.equal?(buffer)
+            buffer.encoding.should == Encoding::ISO_8859_1
           end
 
           describe 'the returned Array' do
@@ -62,7 +78,7 @@ describe 'UDPSocket#recvfrom_nonblock' do
             end
 
             it 'contains an Array at index 1' do
-              @array[1].should be_an_instance_of(Array)
+              @array[1].should.instance_of?(Array)
             end
           end
 
diff --git a/spec/ruby/library/socket/udpsocket/remote_address_spec.rb b/spec/ruby/library/socket/udpsocket/remote_address_spec.rb
index 94889ce560..d1310200fc 100644
--- a/spec/ruby/library/socket/udpsocket/remote_address_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/remote_address_spec.rb
@@ -28,7 +28,7 @@ describe 'UDPSocket#remote_address' do
       end
 
       it 'returns an Addrinfo' do
-        @sock.remote_address.should be_an_instance_of(Addrinfo)
+        @sock.remote_address.should.instance_of?(Addrinfo)
       end
 
       describe 'the returned Addrinfo' do
diff --git a/spec/ruby/library/socket/udpsocket/send_spec.rb b/spec/ruby/library/socket/udpsocket/send_spec.rb
index 5d5de684af..63f5b0dcc6 100644
--- a/spec/ruby/library/socket/udpsocket/send_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/send_spec.rb
@@ -34,7 +34,7 @@ describe "UDPSocket#send" do
 
     @msg[0].should == "ad hoc"
     @msg[1][0].should == "AF_INET"
-    @msg[1][1].should be_kind_of(Integer)
+    @msg[1][1].should.is_a?(Integer)
     @msg[1][3].should == "127.0.0.1"
   end
 
@@ -46,7 +46,7 @@ describe "UDPSocket#send" do
 
     @msg[0].should == "ad hoc"
     @msg[1][0].should == "AF_INET"
-    @msg[1][1].should be_kind_of(Integer)
+    @msg[1][1].should.is_a?(Integer)
     @msg[1][3].should == "127.0.0.1"
   end
 
@@ -59,16 +59,16 @@ describe "UDPSocket#send" do
 
     @msg[0].should == "connection-based"
     @msg[1][0].should == "AF_INET"
-    @msg[1][1].should be_kind_of(Integer)
+    @msg[1][1].should.is_a?(Integer)
     @msg[1][3].should == "127.0.0.1"
   end
 
-  it "raises EMSGSIZE if data is too too big" do
+  it "raises EMSGSIZE if data is too big" do
     @socket = UDPSocket.open
     begin
       -> do
         @socket.send('1' * 100_000, 0, SocketSpecs.hostname, @port.to_s)
-      end.should raise_error(Errno::EMSGSIZE)
+      end.should.raise(Errno::EMSGSIZE)
     ensure
       @socket.send("ad hoc", 0, SocketSpecs.hostname, @port)
       @socket.close
@@ -96,7 +96,7 @@ describe 'UDPSocket#send' do
     describe 'using a disconnected socket' do
       describe 'without a destination address' do
         it "raises #{SocketSpecs.dest_addr_req_error}" do
-          -> { @client.send('hello', 0) }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> { @client.send('hello', 0) }.should.raise(SocketSpecs.dest_addr_req_error)
         end
       end
 
@@ -108,7 +108,7 @@ describe 'UDPSocket#send' do
         it 'does not persist the connection after sending data' do
           @client.send('hello', 0, @addr.ip_address, @addr.ip_port)
 
-          -> { @client.send('hello', 0) }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> { @client.send('hello', 0) }.should.raise(SocketSpecs.dest_addr_req_error)
         end
       end
 
diff --git a/spec/ruby/library/socket/udpsocket/write_spec.rb b/spec/ruby/library/socket/udpsocket/write_spec.rb
index c971f29b62..d41ee078d8 100644
--- a/spec/ruby/library/socket/udpsocket/write_spec.rb
+++ b/spec/ruby/library/socket/udpsocket/write_spec.rb
@@ -12,7 +12,7 @@ describe "UDPSocket#write" do
 
       -> do
         s2.write('1' * 100_000)
-      end.should raise_error(Errno::EMSGSIZE)
+      end.should.raise(Errno::EMSGSIZE)
     ensure
       s1.close if s1 && !s1.closed?
       s2.close if s2 && !s2.closed?
diff --git a/spec/ruby/library/socket/unixserver/accept_nonblock_spec.rb b/spec/ruby/library/socket/unixserver/accept_nonblock_spec.rb
index 30688b46b6..531d851658 100644
--- a/spec/ruby/library/socket/unixserver/accept_nonblock_spec.rb
+++ b/spec/ruby/library/socket/unixserver/accept_nonblock_spec.rb
@@ -2,89 +2,84 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "UNIXServer#accept_nonblock" do
+  before :each do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.open(@path)
+    @client = UNIXSocket.open(@path)
 
-  platform_is_not :windows do
-    before :each do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.open(@path)
-      @client = UNIXSocket.open(@path)
+    @socket = @server.accept_nonblock
+    @client.send("foobar", 0)
+  end
 
-      @socket = @server.accept_nonblock
-      @client.send("foobar", 0)
-    end
+  after :each do
+    @socket.close
+    @client.close
+    @server.close
+    SocketSpecs.rm_socket @path
+  end
 
-    after :each do
-      @socket.close
-      @client.close
-      @server.close
-      SocketSpecs.rm_socket @path
-    end
+  it "accepts a connection in a non-blocking way" do
+    data = @socket.recvfrom(6).first
+    data.should == "foobar"
+  end
 
-    it "accepts a connection in a non-blocking way" do
-      data = @socket.recvfrom(6).first
-      data.should == "foobar"
-    end
+  it "returns a UNIXSocket" do
+    @socket.should.is_a?(UNIXSocket)
+  end
 
-    it "returns a UNIXSocket" do
-      @socket.should be_kind_of(UNIXSocket)
-    end
+  it 'returns :wait_readable in exceptionless mode' do
+    @server.accept_nonblock(exception: false).should == :wait_readable
+  end
+end
+
+describe 'UNIXServer#accept_nonblock' do
+  before do
+    @path   = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+  end
 
-    it 'returns :wait_readable in exceptionless mode' do
-      @server.accept_nonblock(exception: false).should == :wait_readable
+  after do
+    @server.close
+    rm_r(@path)
+  end
+
+  describe 'without a client' do
+    it 'raises IO::WaitReadable' do
+      -> { @server.accept_nonblock }.should.raise(IO::WaitReadable)
     end
   end
-end
 
-with_feature :unix_socket do
-  describe 'UNIXServer#accept_nonblock' do
+  describe 'with a client' do
     before do
-      @path   = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
+      @client = UNIXSocket.new(@path)
     end
 
     after do
-      @server.close
-      rm_r(@path)
+      @client.close
+      @socket.close if @socket
     end
 
-    describe 'without a client' do
-      it 'raises IO::WaitReadable' do
-        -> { @server.accept_nonblock }.should raise_error(IO::WaitReadable)
+    describe 'without any data' do
+      it 'returns a UNIXSocket' do
+        @socket = @server.accept_nonblock
+        @socket.should.instance_of?(UNIXSocket)
       end
     end
 
-    describe 'with a client' do
+    describe 'with data available' do
       before do
-        @client = UNIXSocket.new(@path)
-      end
-
-      after do
-        @client.close
-        @socket.close if @socket
+        @client.write('hello')
       end
 
-      describe 'without any data' do
-        it 'returns a UNIXSocket' do
-          @socket = @server.accept_nonblock
-          @socket.should be_an_instance_of(UNIXSocket)
-        end
+      it 'returns a UNIXSocket' do
+        @socket = @server.accept_nonblock
+        @socket.should.instance_of?(UNIXSocket)
       end
 
-      describe 'with data available' do
-        before do
-          @client.write('hello')
-        end
-
-        it 'returns a UNIXSocket' do
+      describe 'the returned UNIXSocket' do
+        it 'can read the data written' do
           @socket = @server.accept_nonblock
-          @socket.should be_an_instance_of(UNIXSocket)
-        end
-
-        describe 'the returned UNIXSocket' do
-          it 'can read the data written' do
-            @socket = @server.accept_nonblock
-            @socket.recv(5).should == 'hello'
-          end
+          @socket.recv(5).should == 'hello'
         end
       end
     end
diff --git a/spec/ruby/library/socket/unixserver/accept_spec.rb b/spec/ruby/library/socket/unixserver/accept_spec.rb
index c05fbe7f22..8f3ea50966 100644
--- a/spec/ruby/library/socket/unixserver/accept_spec.rb
+++ b/spec/ruby/library/socket/unixserver/accept_spec.rb
@@ -1,115 +1,124 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-platform_is_not :windows do
-  describe "UNIXServer#accept" do
-    before :each do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.open(@path)
-    end
+describe "UNIXServer#accept" do
+  before :each do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.open(@path)
+  end
 
-    after :each do
-      @server.close if @server
-      SocketSpecs.rm_socket @path
-    end
+  after :each do
+    @server.close if @server
+    SocketSpecs.rm_socket @path
+  end
 
-    it "accepts what is written by the client" do
-      client = UNIXSocket.open(@path)
+  it "accepts what is written by the client" do
+    client = UNIXSocket.open(@path)
 
-      client.send('hello', 0)
+    client.send('hello', 0)
 
-      sock = @server.accept
-      begin
-        data, info = sock.recvfrom(5)
+    sock = @server.accept
+    begin
+      data, info = sock.recvfrom(5)
 
-        data.should == 'hello'
-        info.should_not be_empty
-      ensure
-        sock.close
-        client.close
-      end
+      data.should == 'hello'
+      info.should_not.empty?
+    ensure
+      sock.close
+      client.close
     end
+  end
 
-    it "can be interrupted by Thread#kill" do
-      t = Thread.new {
-        @server.accept
-      }
-      Thread.pass while t.status and t.status != "sleep"
-
-      # kill thread, ensure it dies in a reasonable amount of time
-      t.kill
-      a = 0
-      while t.alive? and a < 5000
-        sleep 0.001
-        a += 1
-      end
-      a.should < 5000
+  it "can be interrupted by Thread#kill" do
+    t = Thread.new {
+      @server.accept
+    }
+    Thread.pass while t.status and t.status != "sleep"
+
+    # kill thread, ensure it dies in a reasonable amount of time
+    t.kill
+    a = 0
+    while t.alive? and a < 5000
+      sleep 0.001
+      a += 1
     end
+    a.should < 5000
+  end
 
-    it "can be interrupted by Thread#raise" do
-      t = Thread.new {
-        -> {
-          @server.accept
-        }.should raise_error(Exception, "interrupted")
-      }
+  it "can be interrupted by Thread#raise" do
+    t = Thread.new {
+      -> {
+        @server.accept
+      }.should.raise(Exception, "interrupted")
+    }
 
-      Thread.pass while t.status and t.status != "sleep"
-      t.raise Exception, "interrupted"
-      t.join
-    end
+    Thread.pass while t.status and t.status != "sleep"
+    t.raise Exception, "interrupted"
+    t.join
   end
 end
 
-with_feature :unix_socket do
-  describe 'UNIXServer#accept' do
+describe 'UNIXServer#accept' do
+  before do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+  end
+
+  after do
+    @server.close
+    rm_r(@path)
+  end
+
+  describe 'without a client' do
+    it 'blocks the calling thread' do
+      -> { @server.accept }.should block_caller
+    end
+  end
+
+  describe 'with a client' do
     before do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
+      @client = UNIXSocket.new(@path)
     end
 
     after do
-      @server.close
-      rm_r(@path)
+      @client.close
+      @socket.close if @socket
     end
 
-    describe 'without a client' do
-      it 'blocks the calling thread' do
-        -> { @server.accept }.should block_caller
+    describe 'without any data' do
+      it 'returns a UNIXSocket' do
+        @socket = @server.accept
+        @socket.should.instance_of?(UNIXSocket)
       end
     end
 
-    describe 'with a client' do
+    describe 'with data available' do
       before do
-        @client = UNIXSocket.new(@path)
+        @client.write('hello')
       end
 
-      after do
-        @client.close
-        @socket.close if @socket
+      it 'returns a UNIXSocket' do
+        @socket = @server.accept
+        @socket.should.instance_of?(UNIXSocket)
       end
 
-      describe 'without any data' do
-        it 'returns a UNIXSocket' do
+      describe 'the returned UNIXSocket' do
+        it 'can read the data written' do
           @socket = @server.accept
-          @socket.should be_an_instance_of(UNIXSocket)
+          @socket.recv(5).should == 'hello'
         end
-      end
 
-      describe 'with data available' do
-        before do
-          @client.write('hello')
+        platform_is_not :windows do
+          it "is set to nonblocking" do
+            require 'io/nonblock'
+            @socket = @server.accept
+            @socket.should.nonblock?
+          end
         end
 
-        it 'returns a UNIXSocket' do
+        it "is set to close on exec" do
           @socket = @server.accept
-          @socket.should be_an_instance_of(UNIXSocket)
-        end
-
-        describe 'the returned UNIXSocket' do
-          it 'can read the data written' do
-            @socket = @server.accept
-            @socket.recv(5).should == 'hello'
-          end
+          @socket.should.close_on_exec?
         end
       end
     end
diff --git a/spec/ruby/library/socket/unixserver/for_fd_spec.rb b/spec/ruby/library/socket/unixserver/for_fd_spec.rb
index 4f3816ad37..be1c2df4d7 100644
--- a/spec/ruby/library/socket/unixserver/for_fd_spec.rb
+++ b/spec/ruby/library/socket/unixserver/for_fd_spec.rb
@@ -1,23 +1,21 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-platform_is_not :windows do
-  describe "UNIXServer#for_fd" do
-    before :each do
-      @unix_path = SocketSpecs.socket_path
-      @unix = UNIXServer.new(@unix_path)
-    end
+describe "UNIXServer.for_fd" do
+  before :each do
+    @unix_path = SocketSpecs.socket_path
+    @unix = UNIXServer.new(@unix_path)
+  end
 
-    after :each do
-      @unix.close if @unix
-      SocketSpecs.rm_socket @unix_path
-    end
+  after :each do
+    @unix.close if @unix
+    SocketSpecs.rm_socket @unix_path
+  end
 
-    it "can calculate the path" do
-      b = UNIXServer.for_fd(@unix.fileno)
-      b.autoclose = false
+  it "can calculate the path" do
+    b = UNIXServer.for_fd(@unix.fileno)
+    b.autoclose = false
 
-      b.path.should == @unix_path
-    end
+    b.path.should == @unix_path
   end
 end
diff --git a/spec/ruby/library/socket/unixserver/initialize_spec.rb b/spec/ruby/library/socket/unixserver/initialize_spec.rb
index 0cc49ef1eb..ca1dd301f0 100644
--- a/spec/ruby/library/socket/unixserver/initialize_spec.rb
+++ b/spec/ruby/library/socket/unixserver/initialize_spec.rb
@@ -1,28 +1,26 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'UNIXServer#initialize' do
-    before do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
-    end
+describe 'UNIXServer#initialize' do
+  before do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+  end
 
-    after do
-      @server.close if @server
-      rm_r @path
-    end
+  after do
+    @server.close if @server
+    rm_r @path
+  end
 
-    it 'returns a new UNIXServer' do
-      @server.should be_an_instance_of(UNIXServer)
-    end
+  it 'returns a new UNIXServer' do
+    @server.should.instance_of?(UNIXServer)
+  end
 
-    it 'sets the socket to binmode' do
-      @server.binmode?.should be_true
-    end
+  it 'sets the socket to binmode' do
+    @server.binmode?.should == true
+  end
 
-    it 'raises Errno::EADDRINUSE when the socket is already in use' do
-      -> { UNIXServer.new(@path) }.should raise_error(Errno::EADDRINUSE)
-    end
+  it 'raises Errno::EADDRINUSE when the socket is already in use' do
+    -> { UNIXServer.new(@path) }.should.raise(Errno::EADDRINUSE)
   end
 end
diff --git a/spec/ruby/library/socket/unixserver/listen_spec.rb b/spec/ruby/library/socket/unixserver/listen_spec.rb
index b90b3bbb09..7938d648c4 100644
--- a/spec/ruby/library/socket/unixserver/listen_spec.rb
+++ b/spec/ruby/library/socket/unixserver/listen_spec.rb
@@ -1,21 +1,19 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'UNIXServer#listen' do
-    before do
-      @path   = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
-    end
+describe 'UNIXServer#listen' do
+  before do
+    @path   = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+  end
 
-    after do
-      @server.close
+  after do
+    @server.close
 
-      rm_r(@path)
-    end
+    rm_r(@path)
+  end
 
-    it 'returns 0' do
-      @server.listen(1).should == 0
-    end
+  it 'returns 0' do
+    @server.listen(1).should == 0
   end
 end
diff --git a/spec/ruby/library/socket/unixserver/new_spec.rb b/spec/ruby/library/socket/unixserver/new_spec.rb
index f831f40bc6..7d0c7bf76e 100644
--- a/spec/ruby/library/socket/unixserver/new_spec.rb
+++ b/spec/ruby/library/socket/unixserver/new_spec.rb
@@ -3,4 +3,10 @@ require_relative 'shared/new'
 
 describe "UNIXServer.new" do
   it_behaves_like :unixserver_new, :new
+
+  it "does not use the given block and warns to use UNIXServer::open" do
+    -> {
+      @server = UNIXServer.new(@path) { raise }
+    }.should complain(/warning: UNIXServer::new\(\) does not take block; use UNIXServer::open\(\) instead/)
+  end
 end
diff --git a/spec/ruby/library/socket/unixserver/open_spec.rb b/spec/ruby/library/socket/unixserver/open_spec.rb
index f2506d9f6f..c49df802d0 100644
--- a/spec/ruby/library/socket/unixserver/open_spec.rb
+++ b/spec/ruby/library/socket/unixserver/open_spec.rb
@@ -5,22 +5,20 @@ require_relative 'shared/new'
 describe "UNIXServer.open" do
   it_behaves_like :unixserver_new, :open
 
-  platform_is_not :windows do
-    before :each do
-      @path = SocketSpecs.socket_path
-    end
+  before :each do
+    @path = SocketSpecs.socket_path
+  end
 
-    after :each do
-      @server.close if @server
-      @server = nil
-      SocketSpecs.rm_socket @path
-    end
+  after :each do
+    @server.close if @server
+    @server = nil
+    SocketSpecs.rm_socket @path
+  end
 
-    it "yields the new UNIXServer object to the block, if given" do
-      UNIXServer.open(@path) do |unix|
-        unix.path.should == @path
-        unix.addr.should == ["AF_UNIX", @path]
-      end
+  it "yields the new UNIXServer object to the block, if given" do
+    UNIXServer.open(@path) do |unix|
+      unix.path.should == @path
+      unix.addr.should == ["AF_UNIX", @path]
     end
   end
 end
diff --git a/spec/ruby/library/socket/unixserver/shared/new.rb b/spec/ruby/library/socket/unixserver/shared/new.rb
index 35395826c9..b537f2a871 100644
--- a/spec/ruby/library/socket/unixserver/shared/new.rb
+++ b/spec/ruby/library/socket/unixserver/shared/new.rb
@@ -2,21 +2,19 @@ require_relative '../../spec_helper'
 require_relative '../../fixtures/classes'
 
 describe :unixserver_new, shared: true do
-  platform_is_not :windows do
-    before :each do
-      @path = SocketSpecs.socket_path
-    end
+  before :each do
+    @path = SocketSpecs.socket_path
+  end
 
-    after :each do
-      @server.close if @server
-      @server = nil
-      SocketSpecs.rm_socket @path
-    end
+  after :each do
+    @server.close if @server
+    @server = nil
+    SocketSpecs.rm_socket @path
+  end
 
-    it "creates a new UNIXServer" do
-      @server = UNIXServer.send(@method, @path)
-      @server.path.should == @path
-      @server.addr.should == ["AF_UNIX", @path]
-    end
+  it "creates a new UNIXServer" do
+    @server = UNIXServer.send(@method, @path)
+    @server.path.should == @path
+    @server.addr.should == ["AF_UNIX", @path]
   end
 end
diff --git a/spec/ruby/library/socket/unixserver/sysaccept_spec.rb b/spec/ruby/library/socket/unixserver/sysaccept_spec.rb
index e59731878a..5970c01114 100644
--- a/spec/ruby/library/socket/unixserver/sysaccept_spec.rb
+++ b/spec/ruby/library/socket/unixserver/sysaccept_spec.rb
@@ -1,51 +1,49 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'UNIXServer#sysaccept' do
+describe 'UNIXServer#sysaccept' do
+  before do
+    @path   = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+  end
+
+  after do
+    @server.close
+
+    rm_r(@path)
+  end
+
+  describe 'without a client' do
+    it 'blocks the calling thread' do
+      -> { @server.sysaccept }.should block_caller
+    end
+  end
+
+  describe 'with a client' do
     before do
-      @path   = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
+      @client = UNIXSocket.new(@path)
     end
 
     after do
-      @server.close
-
-      rm_r(@path)
+      Socket.for_fd(@fd).close if @fd
+      @client.close
     end
 
-    describe 'without a client' do
-      it 'blocks the calling thread' do
-        -> { @server.sysaccept }.should block_caller
+    describe 'without any data' do
+      it 'returns an Integer' do
+        @fd = @server.sysaccept
+        @fd.should.is_a?(Integer)
       end
     end
 
-    describe 'with a client' do
+    describe 'with data available' do
       before do
-        @client = UNIXSocket.new(@path)
-      end
-
-      after do
-        Socket.for_fd(@fd).close if @fd
-        @client.close
+        @client.write('hello')
       end
 
-      describe 'without any data' do
-        it 'returns an Integer' do
-          @fd = @server.sysaccept
-          @fd.should be_kind_of(Integer)
-        end
-      end
-
-      describe 'with data available' do
-        before do
-          @client.write('hello')
-        end
-
-        it 'returns an Integer' do
-          @fd = @server.sysaccept
-          @fd.should be_kind_of(Integer)
-        end
+      it 'returns an Integer' do
+        @fd = @server.sysaccept
+        @fd.should.is_a?(Integer)
       end
     end
   end
diff --git a/spec/ruby/library/socket/unixsocket/addr_spec.rb b/spec/ruby/library/socket/unixsocket/addr_spec.rb
index e8431bea16..b3ae2af5d8 100644
--- a/spec/ruby/library/socket/unixsocket/addr_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/addr_spec.rb
@@ -2,35 +2,32 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "UNIXSocket#addr" do
+  before :each do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.open(@path)
+    @client = UNIXSocket.open(@path)
+  end
 
-  platform_is_not :windows do
-    before :each do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.open(@path)
-      @client = UNIXSocket.open(@path)
-    end
-
-    after :each do
-      @client.close
-      @server.close
-      SocketSpecs.rm_socket @path
-    end
+  after :each do
+    @client.close
+    @server.close
+    SocketSpecs.rm_socket @path
+  end
 
-    it "returns an array" do
-      @client.addr.should be_kind_of(Array)
-    end
+  it "returns an array" do
+    @client.addr.should.is_a?(Array)
+  end
 
-    it "returns the address family of this socket in an array" do
-      @client.addr[0].should == "AF_UNIX"
-      @server.addr[0].should == "AF_UNIX"
-    end
+  it "returns the address family of this socket in an array" do
+    @client.addr[0].should == "AF_UNIX"
+    @server.addr[0].should == "AF_UNIX"
+  end
 
-    it "returns the path of the socket in an array if it's a server" do
-      @server.addr[1].should == @path
-    end
+  it "returns the path of the socket in an array if it's a server" do
+    @server.addr[1].should == @path
+  end
 
-    it "returns an empty string for path if it's a client" do
-      @client.addr[1].should == ""
-    end
+  it "returns an empty string for path if it's a client" do
+    @client.addr[1].should == ""
   end
 end
diff --git a/spec/ruby/library/socket/unixsocket/initialize_spec.rb b/spec/ruby/library/socket/unixsocket/initialize_spec.rb
index 13b6972f03..ac30b93de0 100644
--- a/spec/ruby/library/socket/unixsocket/initialize_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/initialize_spec.rb
@@ -1,38 +1,56 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'UNIXSocket#initialize' do
-    describe 'using a non existing path' do
+describe 'UNIXSocket#initialize' do
+  describe 'using a non existing path' do
+    platform_is_not :windows do
       it 'raises Errno::ENOENT' do
-        -> { UNIXSocket.new(SocketSpecs.socket_path) }.should raise_error(Errno::ENOENT)
+        -> { UNIXSocket.new(SocketSpecs.socket_path) }.should.raise(Errno::ENOENT)
       end
     end
 
-    describe 'using an existing socket path' do
-      before do
-        @path = SocketSpecs.socket_path
-        @server = UNIXServer.new(@path)
-        @socket = UNIXSocket.new(@path)
+    platform_is :windows do
+      # Why, Windows, why?
+      it 'raises Errno::ECONNREFUSED' do
+        -> { UNIXSocket.new(SocketSpecs.socket_path) }.should.raise(Errno::ECONNREFUSED)
       end
+    end
+  end
 
-      after do
-        @socket.close
-        @server.close
-        rm_r(@path)
-      end
+  describe 'using an existing socket path' do
+    before do
+      @path = SocketSpecs.socket_path
+      @server = UNIXServer.new(@path)
+      @socket = UNIXSocket.new(@path)
+    end
 
-      it 'returns a new UNIXSocket' do
-        @socket.should be_an_instance_of(UNIXSocket)
-      end
+    after do
+      @socket.close
+      @server.close
+      rm_r(@path)
+    end
 
-      it 'sets the socket path to an empty String' do
-        @socket.path.should == ''
-      end
+    it 'returns a new UNIXSocket' do
+      @socket.should.instance_of?(UNIXSocket)
+    end
+
+    it 'sets the socket path to an empty String' do
+      @socket.path.should == ''
+    end
 
-      it 'sets the socket to binmode' do
-        @socket.binmode?.should be_true
+    it 'sets the socket to binmode' do
+      @socket.binmode?.should == true
+    end
+
+    platform_is_not :windows do
+      it 'sets the socket to nonblock' do
+        require 'io/nonblock'
+        @socket.should.nonblock?
       end
     end
+
+    it 'sets the socket to close on exec' do
+      @socket.should.close_on_exec?
+    end
   end
 end
diff --git a/spec/ruby/library/socket/unixsocket/inspect_spec.rb b/spec/ruby/library/socket/unixsocket/inspect_spec.rb
index d2e3cabbd3..77bb521069 100644
--- a/spec/ruby/library/socket/unixsocket/inspect_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/inspect_spec.rb
@@ -2,16 +2,14 @@ require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
 describe "UNIXSocket#inspect" do
-  platform_is_not :windows do
-    it "returns sockets fd for unnamed sockets" do
-      begin
-        s1, s2 = UNIXSocket.socketpair
-        s1.inspect.should == "#<UNIXSocket:fd #{s1.fileno}>"
-        s2.inspect.should == "#<UNIXSocket:fd #{s2.fileno}>"
-      ensure
-        s1.close
-        s2.close
-      end
+  it "returns sockets fd for unnamed sockets" do
+    begin
+      s1, s2 = UNIXSocket.socketpair
+      s1.inspect.should == "#<UNIXSocket:fd #{s1.fileno}>"
+      s2.inspect.should == "#<UNIXSocket:fd #{s2.fileno}>"
+    ensure
+      s1.close
+      s2.close
     end
   end
 end
diff --git a/spec/ruby/library/socket/unixsocket/local_address_spec.rb b/spec/ruby/library/socket/unixsocket/local_address_spec.rb
index cbf315f9f4..fc504698c3 100644
--- a/spec/ruby/library/socket/unixsocket/local_address_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/local_address_spec.rb
@@ -1,96 +1,92 @@
 require_relative '../spec_helper'
 require_relative '../fixtures/classes'
 
-with_feature :unix_socket do
-  describe 'UNIXSocket#local_address' do
-    before do
-      @path   = SocketSpecs.socket_path
-      @server = UNIXServer.new(@path)
-      @client = UNIXSocket.new(@path)
-    end
+describe 'UNIXSocket#local_address' do
+  before do
+    @path   = SocketSpecs.socket_path
+    @server = UNIXServer.new(@path)
+    @client = UNIXSocket.new(@path)
+  end
 
-    after do
-      @client.close
-      @server.close
+  after do
+    @client.close
+    @server.close
 
-      rm_r(@path)
-    end
-
-    it 'returns an Addrinfo' do
-      @client.local_address.should be_an_instance_of(Addrinfo)
-    end
+    rm_r(@path)
+  end
 
-    describe 'the returned Addrinfo' do
-      platform_is_not :aix do
-        it 'uses AF_UNIX as the address family' do
-          @client.local_address.afamily.should == Socket::AF_UNIX
-        end
+  it 'returns an Addrinfo' do
+    @client.local_address.should.instance_of?(Addrinfo)
+  end
 
-        it 'uses PF_UNIX as the protocol family' do
-          @client.local_address.pfamily.should == Socket::PF_UNIX
-        end
+  describe 'the returned Addrinfo' do
+    platform_is_not :aix do
+      it 'uses AF_UNIX as the address family' do
+        @client.local_address.afamily.should == Socket::AF_UNIX
       end
 
-      it 'uses SOCK_STREAM as the socket type' do
-        @client.local_address.socktype.should == Socket::SOCK_STREAM
+      it 'uses PF_UNIX as the protocol family' do
+        @client.local_address.pfamily.should == Socket::PF_UNIX
       end
+    end
 
-      platform_is_not :aix do
-        it 'uses an empty socket path' do
-          @client.local_address.unix_path.should == ''
-        end
-      end
+    it 'uses SOCK_STREAM as the socket type' do
+      @client.local_address.socktype.should == Socket::SOCK_STREAM
+    end
 
-      it 'uses 0 as the protocol' do
-        @client.local_address.protocol.should == 0
+    platform_is_not :aix do
+      it 'uses an empty socket path' do
+        @client.local_address.unix_path.should == ''
       end
     end
+
+    it 'uses 0 as the protocol' do
+      @client.local_address.protocol.should == 0
+    end
   end
 end
 
-with_feature :unix_socket do
-  describe 'UNIXSocket#local_address with a UNIX socket pair' do
-    before :each do
-      @sock, @sock2 = Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
-    end
+describe 'UNIXSocket#local_address with a UNIX socket pair' do
+  before :each do
+    @sock, @sock2 = Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
+  end
 
-    after :each do
-      @sock.close
-      @sock2.close
-    end
+  after :each do
+    @sock.close
+    @sock2.close
+  end
 
-    it 'returns an Addrinfo' do
-      @sock.local_address.should be_an_instance_of(Addrinfo)
-    end
+  it 'returns an Addrinfo' do
+    @sock.local_address.should.instance_of?(Addrinfo)
+  end
 
-    describe 'the returned Addrinfo' do
-      it 'uses AF_UNIX as the address family' do
-        @sock.local_address.afamily.should == Socket::AF_UNIX
-      end
+  describe 'the returned Addrinfo' do
+    it 'uses AF_UNIX as the address family' do
+      @sock.local_address.afamily.should == Socket::AF_UNIX
+    end
 
-      it 'uses PF_UNIX as the protocol family' do
-        @sock.local_address.pfamily.should == Socket::PF_UNIX
-      end
+    it 'uses PF_UNIX as the protocol family' do
+      @sock.local_address.pfamily.should == Socket::PF_UNIX
+    end
 
-      it 'uses SOCK_STREAM as the socket type' do
-        @sock.local_address.socktype.should == Socket::SOCK_STREAM
-      end
+    it 'uses SOCK_STREAM as the socket type' do
+      @sock.local_address.socktype.should == Socket::SOCK_STREAM
+    end
 
-      it 'raises SocketError for #ip_address' do
-        -> {
-          @sock.local_address.ip_address
-        }.should raise_error(SocketError, "need IPv4 or IPv6 address")
-      end
+    it 'raises SocketError for #ip_address' do
+      -> {
+        @sock.local_address.ip_address
+      }.should.raise(SocketError, "need IPv4 or IPv6 address")
+    end
 
-      it 'raises SocketError for #ip_port' do
-        -> {
-          @sock.local_address.ip_port
-        }.should raise_error(SocketError, "need IPv4 or IPv6 address")
-      end
+    it 'raises SocketError for #ip_port' do
+      -> {
+        @sock.local_address.ip_port
+      }.should.raise(SocketError, "need IPv4 or IPv6 address")
+    end
 
-      it 'uses 0 as the protocol' do
-        @sock.local_address.protocol.should == 0
-      end
+    it 'uses 0 as the protocol' do
+      @sock.local_address.protocol.should == 0
     end
   end
 end
diff --git a/spec/ruby/library/socket/unixsocket/new_spec.rb b/spec/ruby/library/socket/unixsocket/new_spec.rb
index 05a6b3eda2..fea2c1e2b7 100644
--- a/spec/ruby/library/socket/unixsocket/new_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/new_spec.rb
@@ -3,4 +3,10 @@ require_relative 'shared/new'
 
 describe "UNIXSocket.new" do
   it_behaves_like :unixsocket_new, :new
+
+  it "does not use the given block and warns to use UNIXSocket::open" do
+    -> {
+      @client = UNIXSocket.new(@path) { raise }
+    }.should complain(/warning: UNIXSocket::new\(\) does not take block; use UNIXSocket::open\(\) instead/)
+  end
 end
diff --git a/spec/ruby/library/socket/unixsocket/open_spec.rb b/spec/ruby/library/socket/unixsocket/open_spec.rb
index ad5048fedd..b5e8c6c23a 100644
--- a/spec/ruby/library/socket/unixsocket/open_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/open_spec.rb
@@ -7,22 +7,20 @@ describe "UNIXSocket.open" do
 end
 
 describe "UNIXSocket.open" do
-  platform_is_not :windows do
-    before :each do
-      @path = SocketSpecs.socket_path
-      @server = UNIXServer.open(@path)
-    end
+  before :each do
+    @path = SocketSpecs.socket_path
+    @server = UNIXServer.open(@path)
+  end
 
-    after :each do
-      @server.close
-      SocketSpecs.rm_socket @path
-    end
+  after :each do
+    @server.close
+    SocketSpecs.rm_socket @path
+  end
 
-    it "opens a unix socket on the specified file and yields it to the block" do
-      UNIXSocket.open(@path) do |client|
-        client.addr[0].should == "AF_UNIX"
-        client.closed?.should == false
-      end
+  it "opens a unix socket on the specified file and yields it to the block" do
+    UNIXSocket.open(@path) do |client|
+      client.addr[0].should == "AF_UNIX"
+      client.should_not.closed?
     end
   end
 end
diff --git a/spec/ruby/library/socket/unixsocket/pair_spec.rb b/spec/ruby/library/socket/unixsocket/pair_spec.rb
index 845ff76ecc..9690142668 100644
--- a/spec/ruby/library/socket/unixsocket/pair_spec.rb
+++ b/spec/ruby/library/socket/unixsocket/pair_spec.rb